Note: Descriptions are shown in the official language in which they were submitted.
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FLOORBOARDS AND METHODS FOR PRODUCTION AND
INSTALLATION THEREOF
The present invention relates to a locking system
for mechanical joining of floorboards, floorboards hav-
ing such a locking system, a method of installing these
floorboards, a method of producing them, a tool as well
as use of such a tool for installation of floorboards.
Technical Field
In some embodiments, the invention is particularly suited
for floorboards which are based on wood material and in the
normal case have a core of wood and which are intended to be
mechanically joined. The following description of prior-art
technique and the objects and features of the invention
will therefore be directed at this field of application
and, above all, rectangular parquet floors which are
joined on long side as well as short side. The invention
is particularly suited for floating floors, i.e. floors
that can move in relation to the base. However, it should
be emphasised that the invention can be used on all types
of existing hard floors, such as homogeneous wooden
floors, wooden floors with a lamellar core or plywood
core, floors with a surface of veneer and a core of wood
fibre, thin laminate floors, floors with a plastic core
and the like. The invention can, of course, also be used
in other types of floorboards which can be machined with
cutting tools, such as subfloors of plywood or particle
board. Even if it is not preferred, the floorboards can
after installation be fixed to the base.
Technical Background of the Inventign
Mechanical joints have in a short time taken great
market shares mainly owing to their superior laying pro-
perties, joint strength and joint quality. Even if the
floor according to WO 9426999 as described in more detail
below and the floor marketed under the trademark Alloc
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have great advantages compared with traditional, glued
floors, further improvements are, however, desirable.
Mechanical joint systems are very convenient for
joining not only of laminate floors but also wooden
floors and composite floors. Such floorboards may consist
of a large number of different materials in the surface,
core and rear side. As will be described below, these
materials can also be included in the different parts
of the joint system, such as strip, locking element and
tongue. A solution involving an integrated strip which
is formed according to, for example, WO 9426999 or
WO 9747834 and which provides the horizontal joint, and
also involving a tongue which provides the vertical
joint, results, however, in costs in the form of material
15- waste in connection with the forming of the mechanical
joint by machining of the board material.
For optimal function, for instance a 15-mm-thick
parquet floor should have a strip which is of a width
which is approximately the same as the thickness of the
floor, i.e. about 15 mm. With a tongue of about 3 mm,
the amount of waste will be 18 mm. The floorboard has
a normal width of about 200 mm. Therefore the amount of
material waste will be about 90. In general, the cost of
material waste will be great if the floorboards consist
of expensive materials, if they are thick or if their
format is small, so that the number of running meters of
joint per square meter of floor will be great.
Certainly the amount of material waste can be reduc-
ed if a strip is used which is in the form of a separate-
ly manufactured aluminium strip which is already fixed to
the floorboard at the factory. Moreover, the aluminium
strip can in a number of applications result in a better
and also more inexpensive joint system than a strip
machined and formed from the core. However, the aluminium
strip is disadvantageous since the investment cost can be
considerable and extensive reconstruction of the factory
may be necessary to convert an existing traditional pro-
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duction line so that floorboards with such a mechanical
joint system can be produced. An advantage of the prior-
art aluminium strip is, however, that the starting format
of the floorboards need not be changed.
When a strip produced by machining of the floorboard
material is involved, the reverse is the case. Thus, the
format of the floorboards must be adjusted so that there
is enough material for forming the strip and the tongue.
For laminate floors, it is often necessary to change also
the width of the decorative paper used. All these adjust-
ments and changes also require costly modifications of
production equipment and great product adaptations.
In addition to the above problems relating to
undesirable material waste and costs of production and
product adaptation, the strip has disadvantages in the
form of its being sensitive to damage during transport
and installation.
To sum up, there is a great need of providing a
mechanical joint at a lower production cost while at the
same time the aim is to maintain the present excellent
properties as regards laying, taking-up, joint quality
and strength. With prior-art solutions, it is not pos-
sible to obtain a low cost without also having to lower
the standards of strength and/or laying function. An
object of the invention therefore is to indicate solu-
tions which aim at reducing the cost while at the same
time strength and function are retained.
An aspect of the invention starts from known floorboards
which have a core, a front side, a rear side and opposite joint
edge portions, of which one is formed as a tongue groove
defined by upper and lower lips and having a bottom end,
and the other is formed as a tongue with an upwardly
directed portion at its free outer end. The tongue groove
has the shape of an undercut groove with an opening, an
inner portion and an inner locking surface. At least
parts of the lower lip are formed integrally with the
core of the floorboard and the tongue has a locking sur-
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face which is designed to coact with the inner locking
surface in the tongue groove of an adjoining floorboard,
when two such floorboards are mechanically joined, so
that their front sides are located in the same surface
plane (HP) and meet at a joint plane (VP) directed per-
pendicular thereto. This technique is disclosed in, inter
alia DE-A-3041781, which will be discussed in more detail
below.
Before that, however, the general technique regard-
ing floorboards and locking systems for mechanical lock-
ing-together of floorboards will be described as a back-
ground of the present invention.
Description of Prior Art
To facilitate the understanding and description of
the present invention as well as the knowledge of the
problems behind the invention, here follows a description
of both the basic construction and the function of floor-
boards according to WO 9426999 and WO 9966151, with refe-
rence to Figs 1-17 in the accompanying drawings. In
applicable parts, the following description of the prior-
art technique also applies to the embodiments of the pre-
sent invention as described below.
Figs 3a and 3b show a floorboard 1 according to
WO 9426999 from above and from below, respectively. The
board 1 is rectangular with an upper side 2, an underside
3, two opposite long sides with joint edge portions 4a
and 4b, and two opposite short sides with joint edge por-
tions 5a and 5b.
The joint edge portions 4a, 4b of the long sides as
well as the joint edge portions 5a, 5b of the short sides
can be joined mechanically without glue in a direction D2
in Fig. 1c, so as to meet in a joint plane VP (marked in
Fig. 2c) and so as to have, in their laid state, their
upper sides in a common surface plane HP (marked in
Fig. 2c).
In the shown embodiment, which is an example of
floorboards according to WO 9426999 (Figs 1-3 in the
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accompanying drawings), the board 1 has a factory-mounted
plane strip 6 which extends along the entire long side
4a and which is made of a flexible, resilient aluminium
sheet. The strip 6 extends outwards beyond the joint
5 plane VP at the joint edge portion 4a. The strip 6 can be
attached mechanically according to the shown embodiment
or else by glue or in some other manner. As stated in
said documents, it is possible to use as material for a
strip that is attached to the floorboard at the factory,
also other strip materials, such as sheet of some other
metal, aluminium or plastic sections. As is also stated
in WO 9426999 and as described and shown in WO 9966151,
the strip 6 can instead be formed integrally with the
board 1, for instance by suitable machining of the core
of the board 1.
In some embodiments, the present invention is usable for
floorboards where the strip or at least part thereof is integrally
formed with the core, and in some embodiments the invention
solves special problems that arise in such floorboards and the
production thereof. The core of the floorboard need not, but
is preferably, made of a uniform material. The strip 6,
however, is always integrated with the board 1, i.e. it
should be formed on the board or be factory-mounted.
In known embodiments according to the above-mention-
ed WO 9426999 and WO 9966151, the width of the strip 6
can be about 30 mm and the thickness about 0.5 mm.
A similar, although shorter strip 6' is arranged
along one short side 5a of the board 1. The part of the
strip 6 projecting beyond the joint plane VP is formed
with a locking element 8 which extends along the entire
.strip 6. The locking element 8 has in its lower part an
operative locking surface 10 facing the joint plane VP
and having a height of, for instance, 0.5 mm. In laying,
this locking surface 10 coacts with a locking groove 14
which is made in the underside 3 of the joint edge por-
tion 4b of the opposite long side of an adjoining board
1'. The strip 6' along the short side is provided with a
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corresponding locking element 8', and the joint edge por-
tion 5b of the opposite short side has a corresponding
locking groove 14'. The edge of the locking grooves 14,
14' facing away from the joint plane VP forms an opera-
tive locking surface 10' for coaction with the operative
locking surface 10 of the locking element.
For mechanical joining of long sides as well as
short sides also in the vertical direction (direction
D1 in Fig. lc), the board 1 is also along its one long
side (joint edge portion 4a) and its one short side
(joint edge portion 5a) formed with a laterally open
recess or tongue groove 16. This is defined upwards by an
upper lip at the joint edge portion 4a, 5a and downwards
by the respective strips 6, 6'. At the opposite edge por-
tions 4b, 5b, there is an upper recess 18 which defines
a locking tongue 20 coacting with the recess or tongue
groove 16 (see Fig. 2a).
Figs la-lc show how two long sides 4a, 4b of two
such boards 1, 1' on a base U can be joined with each
other by downward angling by pivoting about a centre C
close to the intersection between the surface plane HP
and the joint plane VP, while the boards are held essen-
tially in contact with each other.
Figs 2a-2c show how the short sides 5a, 5b of the
boards 1, 1' can be joined together by snap action. The
long sides 4a, 4b can be joined by means of both methods,
whereas the joining of the short sides 5a, 5b - after
laying of the first row of floorboards - is normally car-
ried out merely by snap action after the long sides 4a,
4b have first been joined.
When a new board 1' and a previously laid board 1
are to be joined along their long side edge portions 4a,
4b according to Figs la-lc, the long side edge portion 4b
of the new board 1' is pressed against the long side edge
portion 4a of the previously laid board 1 according to
Fig. la, so that the locking tongue 20 is inserted into
the recess or tongue groove 16. The board 1' is then
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angled down towards the subfloor U according to Fig. lb.
The locking tongue 20 enters completely the recess or
tongue groove 16 while at the same time the locking ele-
ment 8 of the strip 6 snaps into the locking groove 14.
During this downward angling, the upper part 9 of the
locking element 8 can be operative and perform guiding of
the new board 1' towards the previously laid board 1.
In their joined position according to Fig. lc, the
boards 1, 1' are certainly locked in the Dl direction as
well as the D2 direction along their long side edge por-
tions 4a, 4b, but the boards 1, 1' can be displaced rela-
tive to each other in the longitudinal direction of the
joint along the long sides (i.e. direction D3).
Figs 2a-2c show how the short side edge portions 5a
and 5b of the boards 1, 1' can be joined mechanically in
the Dl as well as the D2 direction by the new board 1'
being displaced essentially horizontally towards the pre-
viously laid board 1. This can in particular be carried
out after the long side of the new board 1' has been
joined, by inward angling according to Figs la-c, with
a previously laid board 1 in an adjoining row. In the
first step in Fig. 2a, bevelled surfaces of the recess
16 and the locking tongue 20 cooperate so that the strip
6' is forced downwards as a direct consequence of the
bringing-together of the short side edge portions 5a, 5b.
During the final bringing-together, the strip 6' snaps up
when the locking element 8' enters the locking groove
14', so that the operative locking surfaces 10, 10' on
the locking element 8' and in the locking groove 14'
engage each other.
By repeating the operations shown in Figs la-c and
2a-c, the entire floor can be laid without glue and along
all joint edges. Thus, prior-art floorboards of the above
type can be joined mechanically by first, as a rule,
being angled downwards on the long side and by the short
sides, when the long side has been locked, being snapped
together by horizontal displacement of the new board 1'
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along the long side of the previously laid board 1
(direction D3). The boards 1, 1' can, without the joint
being damaged, be taken up again in reverse order of
laying and then be laid once more. Parts of these laying
principles are applicable also in connection with the
present invention.
To function optimally and to allow easy laying and
taking-up again, the prior-art boards should, after being
joined, along their long sides be able to take a position
where there is a possibility of a minor play between the
operative locking surface 10 of the locking element and
the operative locking surface 10' of the locking groove
14. However, no play is necessary in the actual butt
joint between the boards in the joint plane VP close to
the upper side of the boards (i.e. in the surface plane
HP). For such a position to be taken, it may be necessary
to press one board against the other. A more detailed
description of this play is to be found in WO 9426999.
Such a play can be in the order of 0.01-0.05 mm between
the operative locking surfaces 10, 10' when pressing the
long sides of adjoining boards against each other. This
play facilitates entering of the locking element 8 in the
locking groove 14, 14' and its leaving the same. As men-
tioned, however, no play is required in the joint between
the boards, where the surface plane HP and the joint
plane VP intersect at the upper side of the floorboards.
The joint system enables displacement along the
joint edge in the locked position after joining of an
optional side. Therefore laying can take place in many
different ways which are all variants of the three basic
methods:
- Angling of long side and snapping in of short side.
- Snapping in of long side - snapping in of short side
- Angling of short side, upward angling of two boards,
displacement of the new board along the short side
edge of the previous board and, finally, downward
angling of two boards.
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The most common and safest laying method is that the
long side is first angled downwards and locked against
another floorboard. Subsequently, a displacement in the
locked position takes place towards the short side of
a third floorboard, so that the snapping-in of the short
side can take place. Laying can also be made by one side,
long side or short side, being snapped together with
another board. Then a displacement in the locked position
takes place until the other side snaps together with a
third board. These two methods require snapping-in of at
least one side. However, laying can also take place with-
out snap action. The third alternative is that the short
side of a first board is angled inwards first towards the
short side of a second board, which is already joined on
its long side with a third board. After this joining-
together, the first and the second board are slightly
angled upwards. The first board is displaced in the
upwardly angled position along its short side until the
upper joint edges of the first and the third board are
in contact with each other, after which the two boards
are jointly angled downwards.
The above-described floorboard and its locking sys-
tem have been very successful on the market in connection
with laminate floors which have a thickness of about 7 mm
and an aluminium strip 6 having a thickness of about
0.6 mm. Similarly, commercial variants of the floorboards
according to WO 9966151 shown in Figs 4a and 4b have been
successful. However, it has been found that this tech-
nique is not particularly suited for floorboards that
are made of wood-fibre-based material, especially massive
wood material or glued laminated wooden material, to form
parquet floors. One reason why this known technique is
not suited for this type of products is the large amount
of material waste that arises owing to the machining of
the edge portions to form a tongue groove having the
necessary depth.
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To partly cope with this problem, it would be pos-
sible to use the technique which is shown in Figs 5a and
5b in the accompanying drawings and which is described
and shown in DE-A-3343601, i.e. it would be possible to
5 form both joint edge portions of separate elements which
are attached to the long side edges. Also this technique
results in high costs of aluminium sections and of the
considerable machining that is required. Moreover, it
is difficult to attach the sectional elements along the
10 edges in a cost-efficient manner. However, the shown
geometry does not allow mounting and dismounting with-
out considerable play by downward and upward angling,
respectively, since the components do not go clear of
each other during these movements if they are manufac-
tured with a close fit (see,Fig. 5b).
Another known design of floorboards with a mechani-
cal locking system is shown in Figs 6a-d in the accom-
panying drawings and is described and shown in CA-A-
0991373. When using this mechanical locking system, all
forces striving to pull the long sides of the boards
apart are taken up by the locking element at the outer
end of the strip (see Fig. 6a). When laying and taking
up the floor, the material must be flexible to allow the
tongue to be released by rotation about two centres at
the same time. A tight fit between all surfaces makes
rational manufacture and displacement in the locked posi-
tion impossible. The short side 6c has no horizontal
lock. This type of mechanical lock, however, causes a
large amount of material waste owing to the design of the
large locking elements.
One more known design of mechanical locking systems
for boards is shown in GB-A-1430429 and Figs 7a-7b in the
accompanying drawings. This system is basically a tongue-
and-groove joint which is provided with an extra holding
hook on an extended lip on one side of the tongue groove
and which has a corresponding holding ridge formed on the
upper side of the tongue. The system requires consider-
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able elasticity of the lip provided with the hook, and
dismounting cannot take place without destroying the
joint edges of the boards. A tight fit makes manufacture
difficult and the geometry of the joint causes a large
amount of material waste.
Another known design of mechanical locking systems
for floorboards is disclosed in DE-A-4242530. Such a
locking system is also shown in Figs 8a-b in the accom-
panying drawings. This known locking system suffers from
several drawbacks. Not only does it cause a large amount
of material waste in manufacture, it is also difficult to
produce in an efficient manner if high-quality joints in
a high-quality floor are desired. The undercut groove
forming the tongue groove can only be made by using a
shank-end mill which is moved along the joint edge. It is
thus not possible to use large disk-shaped cutting tools
to machine the board from the side edge.
For mechanical joining of different types of boards,
in particular floorboards, there are many suggestions, in
which the amount of material waste is small and in which
production can take place in an efficient manner also
when using wood-fibre- and wood-based board materials.
Thus, WO 9627721 (Figs 9a-b in the accompanying drawings)
and JP 3169967 (Figs 10a-b in the accompanying drawings)
disclose two types of snap joints which produce a small
amount of waste but which have the drawback that they
do not allow dismounting of the floorboards by upward
angling. It is true that these joint systems can be made
in an efficient manner using large disk-shaped cutting
tools, but they have the serious drawback that dismount-
ing by upward angling would cause so serious damage to
the locking system that the boards could not be laid once
more by mechanical locking.
Another known system is disclosed in DE-A-1212275
and shown in Figs lla-b in the accompanying drawings.
This known system is suited for sports floors of plastic
material and cannot be manufactured by means of large
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disk-shaped cutting tools for forming the sharply under-
cut groove. Also this known system cannot be dismounted
by upward angling without the material having so great
elasticity that the upper and lower lips round the under-
cut groove are greatly deformed while being pulled apart.
This type of joint is therefore not suited for floor-
boards that are based on wood-fibre-based material, if
high-quality joints are desired.
Tongue-and-groove joints having an inclined groove
and tongue have also been suggested according to US-A-
1124228. The type of joint which is shown in Figs 12c-d
in the accompanying drawings, makes it possible to mount
a new board by pushing it down over the obliquely upward-
ly directed tongue on the previously laid board. To
secure the newly laid board, use is made of nails which'
are driven obliquely down through the board above the
obliquely upwardly directed tongue. In the embodiment
according to Figs 12a-b, this technique cannot be used
since a dovetail joint is used. This technique certainly
causes a small amount of material waste but is not at
all suitable if a floating floor is to be provided, with
individual floorboards which, without being damaged, are
to be mounted and dismounted in a simple manner and which
have high-quality joints.
DE-A-3041781 discloses and shows a locking system
for joining of boards, especially for making roller-
skating rings and bowling alleys of plastic material.
Such a joint system is also shown in Figs 13a-d in the
accompanying drawings. This system comprises an undercut
longitudinal groove along one edge of the board and a
projecting upwardly bent tongue along the opposite edge
of the board. In cross-section, the undercut groove has
a first portion which is defined by parallel surface por-
tions and is parallel with the principal plane of the
board, and a second interior portion which is trapezoidal
or semi-trapezoidal (Figs 13a-b and Figs 13c-d, respec-
tively, in the accompanying drawings). In cross-section,
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the tongue has two plane-parallel portions angled rela-
tive to each other, where the portion closest to the cen-
tre of the board is parallel with the principal plane of
the board and where the outer free portion is angled in
the upward direction in correspondence with the corre-
sponding surface portion within the trapezoidal part of
the undercut groove.
The design of the tongue and groove as well as the
edge portions of the board is such that when two such
boards are mechanically joined, engagement is obtained
between on the one hand the surface portions of the
tongue and corresponding surface portions of the undercut
groove along the entire upper side and outer end of the
tongue as well as along the underside of the inner plane-
parallel portion of the tongue and, on the other hand,
between the edge surfaces of the joined boards above and
below the tongue and the groove, respectively. When a new
board is to be joined with a previously laid board, the
new board is angled upwards at a suitable angle for
insertion of the angled outer portion of the tongue into
the outer plane-parallel part of the groove in the pre-
viously laid board. Subsequently the tongue is inserted
into the groove while the new board is being angled down-
wards. Owing to the angular shape of the tongue, a con-
siderable amount of play is necessary in the first part
of the groove to allow this insertion and inward angling
to be carried out. Alternatively, a considerable degree
of elasticity of the floor material is necessary, which
according to the document should consist of plastic mate-
rial. In the laid joined position, there is engagement
between the major part of the surfaces of the tongue and
the undercut groove except below the upwardly angled
outer portion of the tongue.
A serious drawback of the mechanical locking system
according to DE-A-3041781 is that it is difficult to pro-
duce. As production method, it is suggested to use a
mushroom-type shank end mill with an outer portion which
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generates the cross-sectionally trapezoidal inner part of
the tongue groove. Such a production method is not parti-
cularly rational and besides causes great tolerance prob-
lems if the production method should be used for produc-
ing floorboards or other boards of wood material for
forming wall panels or parquet floorboards having high-
quality joints.
As mentioned above, a drawback of this prior-art
mechanical locking system is that the insertion of the
angled tongue into the groove requires a considerable
amount of play between tongue and groove (see Fig. 5 in
DE-A-3041781 and Fig. 13b in the accompanying drawings)
for downward angling to take place, if there is not a
considerable degree of elasticity in the board material.
Moreover, such downward angling cannot be carried out
while the new board and the previously laid board are
brought together in such manner that they touch each
other close to the upper edge of the boards above the
tongue and groove respectively, so that the pivoting
centre of the downward angling motion is positioned at
this point.
One more drawback of this prior-art mechanical
locking system according to DE-A-3041781 in connection
with fairly thick boards of wood material is that a
displacement of the new board along the previously laid
board in the laid or partly raised position is made much
more difficult by the boards engaging with each other
along large surface portions. Even if the machining of
wooden boards or boards based on wood fibre would be
carried out very accurately, these surface portions are
for natural reasons not quite smooth but have projecting
fibres, which significantly increase friction. When lay-
ing parquet floors or the like, long boards (frequently
2-2.4-m-long and 0.2-0.4-m-wide boards) and essentially
natural materials are involved. This type of long boards
warp and will therefore often deviate from a completely
float shape (they have "banana" shape). In those cases,
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it will be still more difficult to displace a newly laid
board along a previously laid board, if a mechanical
locking-together of the boards also at the short sides is
desired.
5 A further drawback of the mechanical locking system
according to DE-A-3041781 is that it is not very suited
in connection with high-quality floors which are made of
wood materials or wood-fibre-based materials and which
therefore require a tight fit in the vertical direction
10 between tongue and groove in order to prevent creaking.
WO 9747834 discloses floorboards with different
types of mechanical locking systems. The locking systems
which are intended for locking together the long sides of
the boards (Figs 2-4, 11 and 22-25 in the document) are
15 designed so as to be mounted and dismounted by a con-
necting and angling movement, while most of those intend-
ed for locking together the short sides of the boards
(Figs 5-10) are designed so as to be connected to each
other by being translatorily pushed towards each other
for connection by means of a snap lock, but these locking
systems at the short sides of the boards cannot be dis-
mounted without being destroyed or, in any case, damaged.
Some of the boards that are disclosed in WO 9747834
and that have been designed for connection and dismount-
ing by an angular motion (Figs 2-4 in WO 9747834 and
Figs 14a-c in the accompanying drawings), have at their
one edge a groove and a strip projecting below the groove
and extending beyond a joint plane where the upper sides
of two joined boards meet. The strip is designed to coact
with an essentially complementarily formed portion on the
opposite edge of the board, so that two similar boards
can be joined. A common feature of these floorboards is
that the upper side of the tongue of the boards and the
corresponding upper boundary surface of the groove are
plane and parallel with the upper side or surface of the
floorboards. The connection of the boards to prevent them
from being pulled apart transversely of the joint plane
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is obtained exclusively by means of locking surfaces on
the one hand on the underside of the tongue and, on the
other hand, on the upper side of the lower lip or strip
below the groove. These locking systems also suffer from
the drawback that they require a strip portion which
extends beyond the joint plane, which causes material
waste also within the joint edge portion where the groove
is formed.
WO 9747834 also discloses mechanical joint systems
which comprise a circular-arc-shaped tongue and a corre-
spondingly formed groove in the opposite side edge of the
floorboard (cf. Figs 14d-14e in the accompanying draw-
ings). When connecting such locking systems, the tip
of the tongue is put towards the opening of the arcuate
groove, after which downward angling is begun. In this
downward angling, there is a large surface contact
between all the arcuate surfaces of tongue and groove.
If this type of joint system would be used for long
boards of wood or wood-based material, it would be very
difficult to obtain a smooth and simple bringing
together. Moreover, the friction between the arcuate
surfaces and between the tip of the tongue and the bottom
of the groove would require considerable forces for dis-
placement of one board along another board in their join-
ed state. This prior-art technique is certainly better
than the one disclosed in the above-mentioned DE-A-
3041781, but it suffers from many drawbacks of that
technique.
US-A-2740167 (see also Figs 15a-b in the accompany-
ing drawings) discloses parquet boards or squares which
are made of wood and which at their opposite edges are
formed with edge portions which are hooked into each
other when laying several parquet squares in a row. One
edge portion has a downwardly directed hook, and the
opposite edge portion has an upwardly directed hook. To
allow insertion of a new parquet board under a previously
laid parquet board, the underside of the upwardly direct-
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17
ed hook is bevelled. The parquet boards that are joined
at a vertical joint plane are secured merely in the
horizontal direction transversely of the joint plane. To
secure the boards also perpendicular to the upper side of
the parquet boards, use is made of a glue layer which has
been spread in advance on the base on which the parquet
floor is to be arranged. A previously laid parquet board
can therefore be raised again merely before the glue
layer has bound. In practice this parquet floor is there-
fore permanently secured to the base after being laid.
CA-A-2252791 shows and describes floorboards which
are formed with a specially designed groove along one
long side and a complementarily formed tongue along the
other long side. As shown in the patent specification
and also in Figs 16a-b in the accompanying drawings,
the tongue and groove are rounded and angled obliquely
upwards to enable joining of one board with another by
the new board being placed close to the laid one and then
being simultaneously raised and angled, after which the
groove is pulled down over the obliquely upwardly direct-
ed tongue during simultaneous bringing together and down-
ward angling. Since tongue and groove are complementarily
formed, it is difficult to connect and, optionally, once
more pull adjoining floorboards apart. A deviation from
the plane form, i.e. the existence of "banana shape",
results in a further obstacle to the connecting of two
such boards. The risk of damage to the tongue is there-
fore great, and the design also causes great frictional
forces between the surfaces of the tongue and groove.
US-A-5797237 discloses a snap lock system for
joining parquet boards. In the accompanying drawings,
Fig. 17a is a section through two joined boards, while
Fig. 17b shows that such a known floorboard cannot be
dismounted by the board being angled upwards relative
to the remaining, lying floorboard. Instead, as shown in
Fig. 4B in the patent specification, both the board that
is to be removed and the board to which it is connected
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18
and which is to remain, must be lifted up to pull out
the tongue from the groove. The system bears great resem-
blance with that disclosed in the above-mentioned US-A-
2740167 (Figs 15a-b in the accompanying drawings) but
with the difference that a short lower lip is formed
below the upper hook-shaped projection or lip. This short
lower lip, however, has no joining effect since there is
a gap between the underside of the tongue and the upper
side of this short lip when two boards are joined.
Besides, this play is necessary for the dismounting
method as shown in Fig. 17c. Certainly, it is stated that
the joint system is a snap joint, but probably the laid
board is angled slightly upwards to let in the tongue
under the hook-shaped lip of this board. This mechanical
locking system can, as also shown in the patent specifi-
cation, be manufactured with the aid of large disk-shaped
cutting tools. There is no undercut groove, whose upper
and lower lips abut against the inserted tongue and lock
this both vertically and horizontally, in this locking
system. Thus the groove has a larger vertical extent than
the corresponding parts of the tongue. The laid floor
will therefore be able to move towards and away from
the base, which will cause creaking in the joints and
unacceptable vertical displacements. Owing to the insuf-
ficient locking, a high-quality joint cannot be obtained
either.
FR-A-2675174 discloses a mechanical joint system for
ceramic tiles which have complementarily formed opposite
edge portions, in which case use is made of separate
spring clips which are mounted at a distance from each
other and which are formed to grasp a bead on the edge
portion of an adjoining tile. The joint system is not
designed for dismounting by pivoting, which is obvious
from Fig. 18a and, in particular, Fig. 18b in the accom-
panying drawings.
Figs 19a and 19b show floorboards which are formed
according to JP 7180333 and are made by extrusion of
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19
metal material. After mounting, it is practically impos-
sible to dismount such floorboards owing to the joint
geometry, which is evident from Fig. 19b.
Finally, Figs 20a and 20b show another known joint
system which is disclosed in GB-A-2117813 and which is
intended for large insulated wall panels. This system
bears great resemblance with the above-mentioned system
according to CA-A-2252791 and the system from WO 974,7834
as shown in Figs 14d and 14e in the accompanying draw-
ings. The system suffers from the same drawbacks as these
last-mentioned two systems and is not suited for effi-
cient production of floorboards based on wood material
or wood fibre material, especially if high-quality joints
in a high-quality floor are desired. The construction
according to this GB publication uses metal sections
as connecting elements and is not openable by upward
angling.
Other prior-art systems are disclosed in, for
instance, DE 20013380U1, JP 2000179137A, DE 3041781,
DE 19925248, DE 20001225, EP 0623724, EP 0976889,
EP 1045083.
As is evident from that stated above, prior-art
systems have both drawbacks and advantages. However, no
locking system is quite suited for rational production
of floorboards with a locking system which is optimal as
regards production technique, waste of material, laying
and taking-up function and which besides can be used for
floors which are to have high quality, strength and func-
tion in their laid state.
An object of some embodiments of the present invention is to
satisfy this need and provide such an optimal locking system for
floorboards and such optimal floorboards. Another object of some
embodiments of the invention is to provide a rational method of
producing floorboards with such a locking system. One more object of
some embodiments of the invention is to provide a new installation
method, which allows easier and more rational laying than does prior
art. Another object of some embodiments of the invention is to
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provide a tool to facilitate the laying of floorboards by
upward angling and joining of floorboards. Yet another
object of some embodiments of the invention is to provide use of
such a tool for laying of floorboards. Further objects of the
5 invention are evident from that stated above as well as from the
following description.
Summary of the Invention
A floorboard and an openable locking system there-
for comprise an undercut groove on one long side of the
10 floorboard and a projecting tongue on the opposite long
side of the floorboard. The undercut groove has a corre-
sponding upwardly directed inner locking surface at a
distance from its tip. The tongue and the undercut groove
are formed to be h.r.o ght together and pulled apart by a
15 pivoting motion, which has its centre close to the inter-
section between the surface planes and the common joint
plane of two adjoining floorboards. The undercut in the
groove of such a locking system is made by means of disk-
shaped cutting tools, whose rotary shafts are inclined
20 relative to each other to form first an inner part of the
undercut portion of the groove and then a locking surface
positioned closer to the opening of the groove. A laying
method for a floor of such boards comprises the steps of
laying a new board adjacent to a previously laid board,
moving the tongue of the new board into the opening of
the undercut groove of the previously laid board, angling
the new board upwards during simultaneous insertion of
the tongue into the undercut groove and simultaneously
angling down the new board to the final position.
What characterises the locking system, the floor-
board and the laying method, according to embodiments of the
invention is, however, stated here. Further advantages and
features of some embodiments of the invention are also evident
from the following description.
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21
Before specific and preferred embodiments of the
invention will be described with reference to the accom-
panying drawings, the basic concept of the invention and
the strength and function requirements will be described.
In some embodiments, the invention is applicable to rectangular
floorboards having a first pair of parallel sides and a second
pair of parallel sides. With a view to simplifying the
description, the first pair is below referred to as long
sides and the second pair as short sides. It should, how-
ever, be pointed that in some embodiments the invention is also
applicable to boards that can be square.
High Joint Quality
By high joint quality is meant a tight fit in the
locked position between the floorboards both vertically
and horizontally. It should be possible to join the
floorboards without very large visible gaps or diffe-
rences in level between the joint edges in the unloaded
as well as in the normally loaded state. In a high-
quality floor, joint gaps and differences in level should
not be greater than 0.2 and 0.1 mm respectively.
Downward Angling with Rotation at Joint Edge and Guiding
As will be evident from the following description,
it should be possible to lock at least one side, prefer-
ably the long side, by downward angling. The downward
angling should be able to take place with a rotation
about a centre close to the intersection between the
surface planes of the floorboards and the joint plane to
be made, i.e. close to the "upper joint edges" of the
boards when contacting each other. Otherwise, it is not
possible to make a joint which in the locked position has
tight joint edges.
It should be possible to terminate the rotation in
a horizontal position, in which the floorboards are lock-
ed vertically without any play, since a play may cause
undesirable differences in level between the joint edges.
Inward angling should also take place in a manner that
simultaneously guides the floorboards towards each other
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22
with tight joint edges and straightens out any banana
shape (i.e. deviation from a straight flat shape of the
floorboard). The locking element and the locking groove
should have guiding means which coact with each other
during inward angling. The downward angling should take
place with great safety without the boards getting stuck
and pinching each other so as to cause a risk of the
locking system being damaged.
Upward Angling about Joint Edge
It should be possible to angle the long side upwards
so that the floorboards can be released. Since the'boards
in the starting position are joined with tight joint
edges, this upward angling must thus also be able to take
place with upper joint edges in contact with each other
and with rotation at the joint edge. This possibility of
upward angling is very important not only when changing
floorboards or moving a floor. Many floorboards are
trial-laid or laid incorrectly adjacent to doors, in
corners etc. during installation. It is a serious draw-
back if the floorboard cannot be easily released without
the joint system being damaged. Nor is it always the case
that a board that can be angled inwards can also be
angled up again. In connection with the downward angling,
a slight downwards bending of the strip usually takes
place, so that the locking element is bent backwards and
downwards and opens. If the joint system is not formed
with suitable angles and radii, the board can after
laying be locked in such manner that taking up is not
possible. The short side can, after the joint of the long
side has been opened by upward angling, usually be pulled
out along the joint edge, but it is advantageous if also
the short side can be opened by upward angling. This is
particularly advantageous when the boards are long, for
instance 2.4 m, which makes pulling out of short sides
difficult. The upward angling should take place with
great safety without the boards getting stuck and pinch-
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23
ing each other so as to cause a risk of the locking sys-
tem being damaged.
Snapping-in
It should possible to lock the short sides by hori-
zontal snapping-in. This requires that parts of the joint
system be flexible and bendable. Even if inward angling
of long sides is much easier and quicker than snapping-
in, it is an advantage in some embodiments if also the long
side can be snapped in, since certain laying operations, for
instance round doors, require that the boards be joined
horizontally.
Cost of Material at Long and Short Side
If the floorboard is, for instance, 1.2*0.2 m, each
square meter of floor surface will have about six times
more long side joints than short side joints. A large
amount of material waste and expensive joint materials
are therefore of less importance on short side than on
long side.
Horizontal Strength
For high strength to be achieved, the locking ele-
ment must as a rule have a high locking angle, so that
the locking element does not snap out. The locking ele-
ment must be high and wide so that it does not break when
subjected to high tensile load as the floor shrinks in
winter owing to the low relative humidity at this time
of the year. This also applies to the material closest
to the locking groove in the other board. The short side
joint should have higher strength than the long side
joint since the tensile load during shrinking in winter
is distributed over a shorter joint length along the
short side than along the long side.
Vertical Strength
It should be possible to keep the boards plane when
subjected to vertical loads. Moreover, motion in the
joint should be avoided since surfaces that are subjected
to pressure and that move relative to each other, for
instance upper joint edges, may cause creaking.
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Displaceability
To make it possible to lock all four sides, it must
be possible for a newly laid board to be displaced in
the locked position along a previously laid board. This
should take place using a reasonable amount of force, for
instance by driving together using a block and hammer,
without the joint edges being damaged and without the
joint system having to be formed with visible play hori-
zontally and vertically. Displaceability is more impor-
tant on long side than on short side since the friction
is there essentially greater owing to a longer joint.
Production
It should be possible to produce the joint system
rationally using large rotating cutting tools having
extremely good accuracy and capacity.
Measuring
A good function, production tolerance and quality
require that the joint profile can be measured conti-
nuously and checked. The critical parts in a mechanical
joint system should be designed in such manner that
production and measurement are facilitated. It should
be possible to produce them with tolerances of a few
hundredths of a millimetre, and it should therefore be
possible to measure them with great accuracy, for
instance in a so-called profile projector. If the joint
system is produced with linear cutting machining, the
joint system will, except for certain production
tolerances, have the same profile over the entire edge
portion. Therefore the joint system can be measured with
great accuracy by cutting out some samples by sawing from
the floorboards and measuring them in the profile
projector or a measuring microscope. Rational production,
however, requires that the joint system can also be
measured quickly and easily without destructive methods,
for instance using gages. This is facilitated if the
critical parts in the locking system are as`few as
possible.
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Optimisation of Long and Short Side
For a floorboard to be manufactured optimally at a
minimum cost, long and short side should be optimised in
view of their different properties as stated above. For
5 instance, the long side should be optimised for downward
angling, upward angling, positioning and displaceability,
while the short side should be optimised for snapping-in
and high strength. An optimally designed floorboard
should thus have different joint systems on long and
10 short side.
Possibility of Moving Transversely of Joint Edge
Wood-based floorboards and floorboards in general
which contain wood fibre swell and shrink as the relative
humidity changes. Swelling and shrinking usually start
15 from above, and the surface layers can therefore move to
a greater extent than the core, i.e. the part of which
the joint system is formed. To prevent the upper joint
edges from rising or being crushed in case of a high
degree of swelling, or joint gaps from arising when
20 drying up, the joint system should be constructed so as
to allow motion that compensates for swelling and shrink-
ing.
Drawbacks of Prior-Art Systems
Figs 4a and 4b show prior-art systems of the type
25 Alloc original and A1locOHome with a projecting strip
that can be angled and snapped together.
Prior-art joint systems according to Figs 9-16 can
produce a mechanical joint with less waste than mecha-
nical locking systems having a projecting and machined
strip. However, all of them do not satisfy the above-
mentioned requirements and do not solve the problems that
the present invention intends to solve.
The snap joints according to Figs 7, 9, 10, 11, 12,
18, 19 cannot be locked or opened by a pivoting motion
round the upper part of the joint edge, and the joints
according to Figs 8, 11, 19 cannot be produced rationally
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26
by machining of board materials with a rotating cutting
tool that has a large tool diameter.
Floorboards according to Figs 12a-b cannot be angled
or snapped but must first be inserted by being pushed in
parallel with the joint edge. The joint according to
Figs 12c-d cannot be snapped. It may possibly be angled
inward, but in that case it must be produced with too
great a play in the joint system. The strength in the
vertical direction is low since upper and lower engaging
surfaces are parallel. The joint is also difficult to
produce and to displace in the locked position since it
does not contain any free surfaces. Moreover, nailing to
the base is suggested, using nails which are driven
obliquely into the floorboard above the tongue directed
obliquely upwards.
The joint systems according to Figs 6c-d, 15a-b and
17a-b are examples of joints that have no vertical lock,
i.e. allow movements perpendicular to the upper side of
the boards.
The inward angling joint according to Figs 14d-e has
a number of drawbacks because it is manufactured and con-
structed according to the principle that it should have
a tight fit and that upper and lower parts of the tongue
and groove follow circular arcs having their centre at
the upper joint edge, i.e. in the intersection between
the joint and surface planes. This joint does not have
the necessary guiding parts, and the joint is difficult
to angle together since it has an incorrect design and
too large engaging surfaces. As a result, it pinches and
suffers from the so-called drawer effect during inward
angling. The strength in the horizontal direction is too
low, which depends on a low upper locking angle and too
small angular difference between the upper and lower
engaging surfaces. Moreover, the front and upper upwardly
angled part of the tongue groove is too small to manage
the forces that are required for a high-quality joint
system. The too large contact surfaces between tongue and
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27
groove, the absence of the necessary free surfaces
without contact and the requirement for a tight fit in
the entire joint make lateral displacement of the
floorboard along the joint edge considerably more
difficult and also renders rational production with the
possibility of achieving good tolerances difficult. Nor
can it be snapped together horizontally.
The joint system according to Figs 16a-b has a
design that does not allow it to be angled together with-
out a considerable degree of material deformation, which
is difficult to achieve in normal board materials that
are suitable for floors. Also in this case, all parts
of the tongue and groove are in contact with each other.
This makes lateral displacement of a board in the locked
position difficult or impossible. Nor is rational machin-
ing possible owing to the fact all surfaces are in con-
tact with each other. Snapping cannot be carried out
either.
The joint system according to Figs 6a-b cannot be
angled together since it is constructed to move about
two pivoting centres simultaneously. It has no horizontal
lock in the tongue groove. All surfaces are in contact
with each other with a tight fit. In practice, the joint
system cannot be displaced and manufactured rationally.
It is intended for use with a locking system which is
shown in Figs 6c-d and is formed on the adjoining per-
pendicularly set edge of the board and which does not
require lateral displacement for connecting purposes.
The joint system according to Figs 8a-b have a
tongue groove which cannot be manufactured with rotating
cutting tools having a large tool diameter. It cannot
snap and is constructed to prevent, by initial stress and
a tight fit adjacent to the outer vertical part of the
strip, lateral displacement.
The joint system according to Figs 5a-b comprises
two aluminium sections. Production with rotating cutting
tools with a large tool diameter for forming the tongue
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28
groove is not feasible. The joint system is formed so
that it is impossible to angle a new board inwards by
its upper joint edge being held in contact with the
upper joint edge of the previously laid board, so that
the inward angling takes place about a pivoting centre
at the intersection between joint plane and surface
plane. To allow inward angling when using this prior-art
system, it is necessary to have a considerable play that
exceeds what is acceptable in normal floorboards where
high-quality, esthetically good joints are required. The
joint system according to Figs 13a-d is difficult to
manufacture since it requires contact over a large sur-
face part of the outer part of the tongue and the tongue
groove. This also makes lateral displacement in the lock-
ed position difficult. The joint geometry makes upward
angling about the upper joint edge impossible.
The Invention
In some embodiments, the invention is based on a first
understanding that by using suitable production methods, essentially
by machining and using tools whose tool diameter signi-
ficantly exceeds the thickness of the board, it is pos-
sible to form advanced shapes rationally with great accu-
racy of wood materials, wood-based boards and plastic
materials, and that this type of machining can be made
in a tongue groove at a distance from the joint plane.
Thus, the shape of the joint system should be adapted to
rational production which should be able to take place
with very narrow tolerances. Such an adaptation, however,
is not allowed to take place at the expense of other
important properties of the floorboard and the locking
system.
In some embodiments, the invention is also based on a second
understanding, which is based on the knowledge of the require-
ments that must be satisfied by a mechanical joint sys-
tem for optimal function. This understanding has made it
possible to satisfy these requirements in a manner that
has previously not been known, viz, by a combination of
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29
a) the design of the joint system with, for instance,
specific angles, radii, play, free surfaces and ratios
between the different parts of the system, and b) optimal
utilisation of the material properties of the core or
core, such as compression, elongation, bending, tensile
strength and compressive strength.
In some embodiments, the invention is further based on a
third understanding that it is possible to provide a joint system
at a lower production cost while at the same time func-
tion and strength can be retained or even, in some cases,
be improved by a combination of manufacturing technique,
joint design, choice of materials and optimisation of
long and short sides.
In some embodiments, the invention is based on a fourth
understanding that the joint system, the manufacturing technique and
the measuring technique must be developed and adjusted
so that the critical parts requiring narrow tolerances
should, to the greatest possible extent, be as few as
possible and also be designed so as to allow measuring
and checking in continuous production.
According to a first aspect of the invention, there
are thus provided a locking system and a floorboard with
such a locking system for mechanical joining of all four
sides of this floorboard in a first vertical direction
Dl, a second horizontal direction D2 and a third direc-
tion D3 perpendicular to the second horizontal direction,
with corresponding sides of other floorboards with iden-
tical locking systems.
The floorboards can on two sides have a disconnect-
ible mechanical joint system, which is of a known type
and which can be laterally displaced in the locked posi-
tion and locked by inward angling about the upper joint
edges or by horizontal snapping. The floorboards have, on
the other two sides, a locking system according to the
invention. The floorboards can also have a locking system
according to the invention on all four sides.
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At least two opposite sides of the floorboard thus
have a joint system which is designed according to the
invention and which comprises a tongue and a tongue
groove defined by upper and lower lips, where the tongue
5 in its outer and upper part has an upwardly directed part
and where the tongue groove in its inner and upper part
has an undercut. The upwardly directed part of the tongue
and the undercut of the tongue groove in the upper lip
have locking surfaces that counteract and prevent hori-
10 zontal separation in a direction D2 transversely of the
joint plane. The tongue and the tongue groove also have
coacting supporting surfaces which prevent vertical sepa-
ration in a direction Dl parallel with the joint plane.
Such supporting surfaces are to be found at least in the
15 bottom part of the tongue and on the lower lip of the
tongue groove. In the upper part, the coacting locking
surfaces can serve as upper supporting surfaces, but the
upper lip of the tongue groove and the tongue can advan-
tageously also have separate upper supporting surfaces.
20 The tongue, the tongue groove, the locking element and
the undercut are designed so that they can be manufactur-
ed by machining using tools which have a greater tool
diameter than the thickness of the floorboard. The tongue
can with its upwardly directed portion be inserted into
25 the tongue groove and its undercut by an inward angling
motion with its centre of rotation close to the inter-
section between the joint plane and the surface plane,
and the tongue can also leave the tongue groove if the
floorboard is pivoted or angled upwards with its upper
30 joint edge in contact with the upper joint edge of an
adjoining floorboard. For the purpose of facilitating
production, measurement, inward angling, upward angling
and lateral displacement in the longitudinal direction
of the joint and counteracting creaking and reducing any
problems owing to swelling/shrinking of the floor mate-
rial, the joint system is formed with surfaces which are
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31
not in contact with each other both during inward angling
and in the locked position.
According to a second aspect of the invention, the
floorboard has two edge portions with a joint system
according to the invention, where the tongue with its
upwardly directed portion both can be inserted into the
tongue groove and its undercut and can leave the tongue
groove by downward angling and upward angling, respec-
tively, by the boards being kept in contact with each
other with their upper joint edges close to the inter-
section between joint plane and surface plane, so that
the pivoting takes place about a pivoting centre close to
this point. Moreover, the locking system can be snapped
together by horizontal displacement, essentially the
lower part of the tongue groove being bent and the lock-
ing element of the tongue snapping into the locking
groove. Alternatively or furthermore, the tongue can be
made flexible to facilitate such snapping-in at the short
side after the long sides of the floorboards have been
joined. Thus, the invention also relates to a snap joint
which can be released by upward angling with upper joint
edges in contact with each other.
According to a third aspect of the invention, the
floorboard has two edge portions with a joint system
which is formed according to the invention, where the
tongue, while the board is held in an upwardly angled
position, can be snapped into the tongue groove and then
be angled down by a pivoting motion about the upper joint
edge. In the upwardly angled position, the tongue can be
partially inserted into the tongue groove by the board
in this position being moved in a translatory movement
to the tongue groove until the upper joint edges have
come into contact with each other, after which downward
angling takes place for final joining of tongue and
tongue groove and for obtaining a locking-together. The
lower lip can be shorter than the upper lip so as to
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enable greater degrees of freedom when designing the
undercut of the upper lip.
A plurality of aspects of the invention are also
applicable to the known systems without these aspects being
combined with the preferred locking systems described here.
In some embodiments, the invention also describes
the basic principles that should be satisfied for a
tongue-and-groove joint which is to be angled inwards with
upper joint edges in contact with each other and which is to
be snapped in with a minimum bending of joint components.
In some embodiments, the invention also describes how
material properties can be used to achieve great strength
and low cost in combination with angling and snapping as
well as laying methods.
In accordance with a broad aspect, there is
provided a flooring system comprising a plurality of
floorboards which are mechanically joinable at a joint plane,
each of said floorboards having a core, a front side, a rear
side and opposite joint edge portions, of which one is formed
as a tongue groove which is defined by upper and lower lips
and has a bottom end, and the other is formed as a tongue
with an upwardly directed portion at its free outer end, the
tongue groove, seen from the joint plane, having the shape of
an undercut groove with an opening, an inner portion and an
inner locking surface, and at least parts of the lower lip
being formed integrally with the core of the floorboard, and
the tongue having a locking surface which is formed to coact
with the inner locking surface in the tongue groove of an
adjoining floorboard, when two such floorboards are
mechanically joined, so that their front sides are positioned
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32a
in the same surface plane and meet at the joint plane
directed perpendicular thereto, wherein at least the major
part of the bottom end of the tongue groove, seen parallel
with the surface plane, is positioned further away from the
joint plane than is the outer end of the tongue, the inner
locking surface of the tongue groove is formed on the upper
lip within the undercut portion of the tongue groove for
coaction with the corresponding locking surface of the
tongue, which locking surface is formed on the upwardly
directed portion of the tongue to counteract pulling apart of
two mechanically joined boards in a direction perpendicular
to the joint plane, the lower lip has a supporting surface
for coaction with a corresponding supporting surface on the
tongue at a distance from the bottom end of the undercut
groove, said supporting surfaces being intended to coact to
counteract a relative displacement of two mechanically joined
boards in a direction perpendicular to the surface plane, all
parts of the portions of the lower lip which are connected
with the core, seen from the point where the surface plane
and the joint plane intersect, are located outside a plane
which is located further away from said point than a locking
plane which is parallel therewith and which is tangent to the
coacting locking surfaces of the tongue groove and the tongue
where said locking surfaces are most inclined relative to the
surface plane, and the upper and lower lips and tongue of the
joint edge portions are designed to enable disconnection of
two mechanically joined floorboards by upward pivoting of one
floorboard relative to the other about a pivoting centre
close to a point of intersection between the surface plane
and the joint plane for disconnection of the tongue of one
floorboard and the tongue groove of the other floorboard.
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In accordance with another broad aspect, there is
provided a floorboard for providing a flooring system, said
floorboard being mechanically joinable with an identical
floorboard at a joint plane, said floorboard having a core, a
front side, a rear side and opposite joint edge portions, of
which one is formed as a tongue groove which is defined by
upper and lower lips and has a bottom end, and the other is
formed as a tongue with an upwardly directed portion at its
free outer end, the tongue groove, seen from the joint plane,
having the shape of an undercut groove with an opening, an
inner portion and an inner locking surface, and at least
parts of the lower lip being formed integrally with the core
of the floorboard, and the tongue having a locking surface
which is formed to coact with the inner locking surface in
the tongue groove of an adjoining floorboard, when the two
floorboards are mechanically joined, so that their front
sides are positioned in the same surface plane and meet at
the joint plane directed perpendicular thereto, wherein at
least the major part of the bottom end of the tongue groove,
seen parallel with the surface plane, is positioned further
away from the joint plane than is the outer end of the
tongue, the inner locking surface of the tongue groove is
formed on the upper lip within the undercut portion of the
tongue groove for coaction with the corresponding locking
surface of the tongue, which locking surface is formed on the
upwardly directed portion of the tongue to counteract pulling
apart of the two mechanically joined boards in a direction
perpendicular to the joint plane, the lower lip has a
supporting surface for coaction with a corresponding
supporting surface on the tongue at a distance from the
bottom end of the undercut groove, said supporting surfaces
being intended to coact to counteract a relative displacement
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32c
of the two mechanically joined boards in a direction
perpendicular to the surface plane, all parts of the portions
of the lower lip which are connected with the core, seen from
the point where the surface plane and the joint plane
intersect, are located outside a plane which is located
further away from said point than a locking plane which is
parallel therewith and which is tangent to the coacting
locking surfaces of the tongue groove and the tongue where
said locking surfaces are most inclined relative to the
surface plane, and the upper and lower lips and tongue of the
joint edge portions are designed to enable disconnection of
the two mechanically joined floorboards by upward pivoting of
one floorboard relative to the other about a pivoting centre
close to a point of intersection between the surface plane
and the joint plane for disconnection of the tongue of one
floorboard and the tongue groove of the other floorboard.
Different aspects of the invention will now be
described in more detail with reference to the accompanying
drawings which show different embodiments of the invention.
The parts of the inventive board that are equivalent to
those of the prior-art board in Figs 1-2 have throughout
been given the same reference numerals.
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Brief Description of the Drawings
Figs la-c show in three steps a downward angling
method for mechanical joining of long sides
of floorboards according to WO 9426999.
Figs 2a-c show in three steps a snapping-in method for
mechanical joining of short sides of floor-
boards according to WO 9426999.
Figs 3a-b show a floorboard according to WO 9426999
seen from above and from below respectively.
Figs 4a-b show two different embodiments of floorboards
according to WO 9966151.
Figs 5a-b show floorboards according to DE-A-3343601.
Figs 6a-d show mechanical locking systems for the
long side and the short side respectively
of floorboards according to CA-A-0991373.
Figs 7a-b show a mechanical locking system according to
GB-A-1430429.
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33
Figs 8a-b show boards according to DE-A-4242530.
Figs 9a-b show a snap joint according to WO 9627721.
Figs 10a-b show a snap joint according to JP 3169967.
Figs 11a-b show a snap joint according to DE-A-1212275.
Figs 12a-d show different embodiments of locking systems
based on tongue and groove according to US-A-
1124228.
Figs 13a-d show a mechanical joint system for sport
floors according to DE-A-3041781.
Figs 14a-e show one of the locking systems as shown in
WO 9747834.
Figs 15a-b show a parquet floor according to US-A-
2740167.
Figs 16a-b show a mechanical locking system for floor-
boards according CA-A-2252791.
Figs 17a-b show a snap-lock system for parquet floors
according to US-A-5797237.
Figs 18a-b show a joint system for ceramic tiles accord-
ing to FR-A-2675174.
Figs 19a-b show a joint system for floorboards which
are described in JP 7180333 and are made by
extrusion of metal material.
Figs 20a-b show a joint system for large wall panels
according to GB-A-2117813.
Figs 21a-b show schematically to parallel joint edge
portions of a first preferred embodiment of
a floorboard according to the present inven-
tion.
Fig. 22 shows schematically the basic principles of
inward angling about upper joint edges when
using the present invention.
Figs 23a-b show schematically the production of a joint
edge of a floorboard according to the inven-
tion.
Figs 24a-b show a production-specific variant of the
invention.
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34
Fig. 25 shows a variant of the invention as well as
snapping-in and upward angling in combination
with bending of the lower lip.
Fig. 26 shows a variant of the invention with a short
lip.
Figs 27a-c show a downward and upward angling method.
Figs 28a-c show an alternative angling method.
Figs 29a-b show a snapping-in method.
Fig. 30 shows how the long sides of two boards are
joined with the long side of a third board
when the two boards are already joined with
each other on the short sides.
Figs 31a-b show two joined floorboards provided with a
combination joint according to the invention.
Figs 32a-d show inward angling of the combination joint.
Fig. 33 shows an example of how a long side can be
formed in a parquet floor.
Fig. 34 shows an example of how a short side can be
formed in a parquet floor.
Fig. 35 shows a detailed example of how the joint
system of the long side can be formed in a
parquet floor.
Fig. 36 shows an example of a floorboard according
to the invention where the joint system is
designed so that it can be angled by using
bending and compression in the joint mate-
rial.
Fig. 37 shows a floorboard according to the inven-
tion.
Figs 38a-b show a manufacturing method in four steps
which uses a manufacturing method according
to the invention.
Fig. 39 shows a joint system which is suitable to
dompensate for swelling and shrinking of the
surface layer of the floorboard.
Fig. 40 shows a variant of the invention with a rigid
tongue.
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Fig. 41 shows a variant of the invention where the
locking surfaces constitute upper contact
surfaces.
Figs 42a-b show a variant of the invention with a long
5 tongue as well as angling and pulling out.
Figs 43a-c show how the joint system should be designed
to facilitate snapping in.
Fig. 44 shows snapping-in in the angled position.
Figs 45a-b show a joint system according to the inven-
10 tion with a flexible tongue.
Figs 46a-b show a joint system according to the inven-
tion with a split and flexible tongue.
Figs 47a-b show a joint system according to the inven-
tion with a lower lip consisting partly of
15 another material than the core.
Figs 48a-b show a joint system which can be used as snap
joint in a floorboard that is locked on all
four sides.
Fig. 49 shows a joint system that can be used, for
20 instance, on the short side of a floorboard.
Fig. 50 shows another example of joint system which
can be used, for instance, on the short side
of a floorboard.
Figs 51a-f show a laying method.
25 Figs 52a-b show laying by means of a specially designed
tool.
Fig. 53 shows joining of short sides.
Figs 54a-b show snapping-in of the short side.
Fig. 55 shows a variant of the invention with a
30 flexible tongue that facilitates snapping-in
on the short side.
Figs 56a-e show snapping-in of the outer corner portion
of the short side.
Figs 57a-e show snapping-in of the inner corner portion
35 of the short side.
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36
Detailed Description of Preferred Embodiments
A first preferred embodiment of a floorboard 1, 1',
which is provided with a mechanical locking system
according to the invention, will now be described with
reference to Figs 21a and 21b. To facilitate the under-
standing, the joint system is shown schematically. It
should be emphasised that a better function can be
achieved with other preferred embodiments that will be
described below.
Figs 21a, 21b show schematically a section through
a joint between a long side edge portion 4a of a board
1 and an opposite long side edge portion 4b of another
board 1'.
The upper sides of the boards are essentially posi-
tioned in a common sia,rface plane HP and the upper parts
of the joint edge portions 4a, 4b engage each other in
a vertical joint plane VP. The mechanical locking system
results in locking of the boards relative to each other
in both the vertical direction Dl and the horizontal
direction D2 which extends perpendicular to the joint
plane VP. During the laying of a floor with juxtaposed
rows of boards, one board (1'), however, can be displaced
along the other board (1) in a direction D3 (see Fig. 3a)
along the joint plane VP. Such a displacement can be
used, for instance, to provide locking-together of floor-
boards that are positioned in the same row.
To provide joining of the two joint edge portions
perpendicular to the vertical plane VP and parallel with
the horizontal plane HP, the edges of the floorboard have
in a manner known per se a tongue groove 36 in one edge
portion 4a of the floorboard inside the joint plane VP,
and a tongue 38 formed in the other joint edge portion 4b
and projecting beyond the joint plane VP.
In this embodiment the board 1 has a core or core 30
of wood which supports a surface layer of wood 32 on its
front side and a balancing layer 34 on its rear side. The
board 1 is rectangular and has a second mechanical lock-
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37
ing system also on the two parallel short sides. In some
embodiments, this second locking system can have the same
design as the locking system of the long sides, but the
locking system on the short sides can also be of a diffe-
rent design according to the invention or be a previously
known mechanical locking system.
As an illustrative, non-limiting example, the floor-
board can be of parquet type with a thickness of 15 mm,
a length of 2.4 m and a width of 0.2 m. The invention,
however, can also be used for parquet squares or boards
of a different size.
The core 30 can be of lamella type and consist of
narrow wooden blocks of an inexpensive kind of wood. The
surface layer 32 may have a thickness of 3-4 mm and con-
sist of a decorative kind of hardwood and be varnished.
The balancing layer 34 of the rear side may consist of a
2 mm veneer layer. In some cases, it may be advantageous
to use different types of wood materials in different
parts of the floorboard for optimal properties within the
individual parts of the floorboard.
As mentioned above, the mechanical locking system
according to the invention comprises a tongue groove 36
in one joint edge portion 4a of the floorboard, and a
tongue 38 on the opposite joint edge portion 4b of the
floorboard.
The tongue groove 36 is defined by upper and lower
lips 39, 40 and has the form of an undercut groove with
an opening between the two lips 39, 40.
The different parts of the tongue groove 36 are best
seen in Fig. 21b. The tongue groove is formed in the core
or core 30 and extends from the edge of the floorboard.
Above the tongue groove, there is an upper edge portion
or joint edge surface 41 which extends up to the surface
plane HP. Inside the opening of the tongue groove, there
is an upper engaging or supporting surface 43 which in
this case is parallel with the surface plane HP. This
engaging or supporting surface passes into an inclined
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38
locking surface 43 which has a locking angle A to the
horizontal plane HP. Inside the locking surface, there is
surface portion 46 which forms the upper boundary surface
of the undercut portion 35 of the tongue groove. The
tongue groove further has a bottom end 48 which extends
down to the lower lip 40. On the upper side of this lip
there is an engaging or supporting surface 50. The outer
end of the lower lip has a joint edge surface 52 and
extends in this case slightly beyond the joint plane VP.
The shape of the tongue is also best seen in
Fig. 21b. The tongue is made of the material of the core
or core 30 and extends beyond the joint plane VP when
this joint edge portion 4b is mechanically joined with
the joint edge portion 4a of an adjoining floorboard. The
joint edge portion 4b also has an upper edge portion or
upper joint edge surface 61 which extends along the joint
plane VP down to the root of the tongue 38. The upper
side of the root of the tongue has an upper engaging or
supporting surface 64 which in this case extends to an
inclined locking surface 65 of an upwardly directed por-
tion 8 close to the tip of the tongue. The locking sur-
face 65 passes into a guiding surface portion 66 which
ends in an upper surface 67 of the upwardly directed
portion 8 of the tongue. After the surface 67 follows
a bevel which may serve as a guiding surface 68. This
extends to the tip 69 of the tongue. At the lower end
of the tip 69 there is a further guiding surface 70
which extends obliquely downwards to the lower edge of
the tongue and an engaging or supporting surface 71. The
supporting surface 71 is intended to coact with the sup-
porting surface 50 of the lower lip when two such floor-
boards are mechanically joined, so that their upper sides
are positioned in the same surface plane HP and meet at
a joint plane VP directed perpendicular thereto, so that
the upper joint edge surface 41, 61 of the boards engage
each other. The tongue has a lower joint edge surface 72
which extends to the underside.
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39
In this embodiment there are separate engaging or
supporting surface 43, 64 in the tongue groove and on the
tongue, respectively, which in the locked state engage
each other and coact with the lower supporting surfaces
50, 71 on the lower lip and on the tongue, respectively,
to provide the locking in the direction Dl perpendicular
to the surface plane HP. In other embodiments, which will
be described below, use is made of the locking surfaces
45, 65 both as locking surfaces for locking together in
the direction D2 parallel with the surface plane HP and
as supporting surfaces for counteracting movements in the
direction D2 perpendicular to the surface plane. In the
embodiment according to Figs 21a, 2b, the locking sur-
faces 45, 65 and the engaging surfaces 43, 64 coact as
upper supporting surfaces in the system.
As is apparent from the drawing, the tongue 38
extends beyond the joint plane VP and has an upwardly
directed portion 8 at its free outer end or tip 69. The
tongue has also a locking surface 65 which is formed to
coact with the inner locking surface 45 in the tongue
groove 36 of an adjoining floorboard when two such floor-
boards are mechanically joined, so that their front sides
are positioned in the same surface plane HP and meet at a
joint plane VP directed perpendicular thereto.
As is evident from Fig. 21b, the tongue 38 has a
surface portion 52 between the locking surface 51 and
the joint plane VP. When two floorboards are joined, the
surface portion 52 engages the surface portion 45 of the
upper lip 8. To facilitate insertion of the tongue into
the undercut groove by inward angling or snapping-in, the
tongue can, as shown in Figs 21a, 21b, have a bevel 66
between the locking surface 65 and the surface portion
57. Moreover, a bevel 68 can be positioned between the
surface portion 57 and the tip 69 of the tongue. The
bevel 66 may serve as a guiding part by having a lower
angle of inclination to the surface plane than the angle
of inclination A of the locking surfaces 43, 51.
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The supporting surface 71 of the tongue is in this
embodiment essentially parallel with the surface plane
HP. The tongue has a bevel 70 between this supporting
surface and the tip 69 of the tongue.
5 According to the invention, the lower lip 40 has a
supporting surface 50 for coaction with the corresponding
supporting surface 71 on the tongue 36 at a distance from
the bottom end 48 of the undercut groove. When two floor-
boards are joined with each other, there is engagement
10 both between the supporting surfaces 50, 71 and between
the engaging or supporting surface 43 of the upper lip 39
and the corresponding engaging or supporting surface 64
of the tongue. In this way, locking of the boards in the
direction Dl perpendicular to the surface plane HP is
15 obtained.
According to the invention, at least the major part
of the bottom end 48 of the undercut groove, seen paral-
lel with the surface plane HP, is located further away
from the joint plane VP than is the outer end or tip 69
20 of the tongue 36. By this design, manufacture is simpli-
fied to a considerable extent, and displacement of one
floorboard relative to another along the joint plane is
facilitated.
Another important feature of a mechanical locking
25 system according to the invention is that all parts of
the portions of the lower lip 40 which are connected with
the core 30, seen from the point C, where the surface
plane HP and the joint plane VP intersect, are located
outside a plane LP2. This plane is located further away
30 from said point C than a locking plane LP1 which is
parallel with the plane LP2 and which is tangent to the
coacting locking surfaces 45, 65 of the undercut groove
36 and the tongue 38, where these locking surfaces are
most inclined relative to the surface plane HP. Owing to
35 this design, the undercut groove can, as will be describ-
ed in more detail below, be made by using large disk-
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41
shaped rotating cutting tools for machining of the edge
portions of the floorboards.
A further important feature of a locking system
according to the present invention is that the upper
and lower lips 39, 40 and tongue 38 of the joint edge
portions 4a, 4b are designed to enable disconnection of
two mechanically joined floorboards by one floorboard
being pivoted upwards relative to the other about a
pivoting centre close to the point of intersection C
between the surface plane HP and the joint plane VP, so
that the tongue of this floorboard is pivoted out of the
undercut groove of the other floorboard.
In the embodiment according to Figs 21a, 21b, such
disconnection is made possible by a slight downward bend-
ing of the lower lip 40. In other more preferred embodi-
ments of the invention, no downward bending of the lower
lip, however, is required in conjunction with connection
and disconnection of the floorboards.
In the embodiment according to Figs 21a, 21b, the
joining of two floorboards according to the invention can
be carried out in three different ways.
One way involves that the board 1' is placed on the
base and moved towards the previously laid board 1' until
the narrow tip 69 of the tongue 38 has been inserted into
the opening of the undercut groove 36. Then the floor-
board 1' is angled upwards so that the upper parts 41,
61 of the boards on both sides of the joint plane VP con-
tact each other. While maintaining this contact, the
board is angled downwards by pivoting about the centre of
pivoting C. The insertion takes place by the bevel 66 of
the tongue sliding along the locking surface 45 of the
upper lip 39 while at the same time the bevel 70 of the
tongue 38 slides against the outer edge of the upper side
of the lower lip 40. The locking system can then be open-
ed by the floorboard 1' being angled upwards by pivoting
about the centre of pivoting C close to the intersection
between the surface plane HP and the joint plane VP.
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42
The second way of locking-together is provided by
moving the new board with its joint edge portion 4a
formed with a tongue groove towards the joint edge por-
tion 4b, provided with a tongue, of the previously laid
board. Then the new board is pivoted upwards until con-
tact is obtained between the upper parts 41, 61 of the
boards close to the intersection between surface plane
and joint plane, after which the board is pivoted down-
wards to bring tongue and groove together until the final
locked position is achieved. According to the following
description, the floorboards can also be joined by one
board being moved in an upwardly angled position towards
the other.
A third way of providing joining of the floorboards
in this embodiment of floorboards according to the inven-
tion involves that the new board 1' is displaced horizon-
tally towards the previously laid board 1, so that the
tongue 38 with its locking element or upwardly directed
portion 8 is inserted into the tongue groove 36, the
lower flexible lip 40 being bent slightly downwards for
the locking element 8 to snap into the undercut portion
35 of the tongue groove. Also in this case, disconnection
takes place by upward angling as described above.
In connection with snapping-in, also a small degree
of upward bending of the upper lip 39 can take place as
can also a certain degree of compression of all the parts
in the groove 36 and the tongue 38 which during snapping-
in are in contact with each other. This facilitates
snapping-in and can be used to form an optimal joint
system.
To facilitate manufacture, inward angling, upward
angling, snapping-in and displaceability in the locked
position and to minimise the risk of creaking, all sur-
faces that are not operative to form a joint with tight
upper joint edges and to form the vertical and horizontal
joint so as not to be in contact with each other in the
locked position and preferably also during locking and
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43
unlocking. This allows manufacture without requiring high
tolerances in these joint portions and reduces the fric-
tion in lateral displacement along the joint edge. Exam-
ples of surfaces or parts of the joint system that should
not be in contact with each other in the locked position
are 46-67, 48-69, 50-70 and 52-72.
The joint system according to the preferred embodi-
ment may consist of several combinations of materials.
The upper lip 39 can be made of a rigid and hard upper
surface layer 32 and a softer lower part which is part
of the core 30. The lower lip 40 can consist of the same
softer upper part 30 and also a lower soft part 34 which
can be another kind of wood. The directions of the fibres
in the three kinds of wood may vary. This can be used to
provide a joint system which utilises these material pro-
perties. The locking element is therefore according to
the invention positioned closer to the upper hard and
rigid part, which thus is flexible and compressible to a
limited extent only, while the snap function is formed in
the softer lower and flexible part. It should be pointed
that the joint system can also be made in a homogeneous
floorboard.
Fig. 22 shows schematically the basic principles of
inward angling about a point C (upper joint edges) when
using the present invention. Fig. 22 shows schematically
how a locking system should be designed to enable inward
angling about the upper joint edges. In this inward
angling, the parts of the joint system follow in prior-
art manner a circular arc with is centre C close to the
intersection between the surface plane HP and the joint
plane VP. If a great play between all parts of the joint
system is allowed, or if essential deformation during
inward angling is possible, the tongue and groove can be
formed in many different ways. If, on the other hand, the
joint system must have contact surfaces that prevent
vertical and horizontal separation without any play
between the engaging or supporting surfaces and if
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44
material deformation is not possible, the joint system
should be constructed according to the following
principles.
The upper part of the joint system is formed as fol-
lows. C1B is a circular arc which has it centre C at the
top at the upper joint edges 41, 61 and which in this
preferred embodiment intersects a contact point between
the upper lip 39 and the upper part of the tongue 38 at
the point P2. All the other contact points between P2,
P3, P4 and P5 between the upper lip 39 and the upper part
8 of the tongue 38 and between this point of intersection
P2 and the vertical plane VP are positioned on or inside
this circular arc C1B, whereas all other contact points
from P2 to P1 between the upper lip 39 and the upper part
of the tongue 38 and between this point of intersection
P2 and the outer part of the tongue 38 are positioned on
or outside this circular arc C1B. These conditions should
be satisfied for all contact points. Regarding the con-
tact point P5 with the circular arc C1A, the case is that
all other contact points between P1 and P5 are positioned
outside the circular arc C1A, and regarding the contact
point P1, all other contact points between P1 and P5 are
positioned inside the circular arc C1C.
The lower part of the joint system is formed accord-
ing to the corresponding principles. C2B is a circular
arc which is concentric with the circular arc C1A and
which in this preferred embodiment intersects a contact
point between the lower lip 40 and the lower part of the
tongue 38 at the point P7. All the other contact points
between P7, P8 and P9 between the lower lip 40 and the
lower part of the tongue 38 and between this point of
intersection P7 and the vertical plane are positioned on
or outside the circular arc C2B, and all other contact
points between P6, P7 and between the lower lip 40 and
the lower part of the tongue 38 and between this point of
intersection P7 and the outer part of the tongue 38 are
positioned on or inside this circular arc C2B. The same
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applies to the contact point P6 with the circular arc
C2A.
A joint system constructed according to this prefer-
red embodiment may have good inward angling properties.
5 It can easily be combined with upper engaging or support-
ing surfaces 43, 64 which can be parallel with the hori-
zontal plane HP and which can thus provide excellent ver-
tical locking.
Figs 23a, 23b show how a joint system according to
10 Figs 21a, 2b can be produced. Normally, the floorboard
1 according to prior art is positioned with its surface
2 downwards on a ball bearing chain in a milling machine
which conveys the board with extremely great accuracy
past a number of milling cutters which, for instance,
15 have a tool diameter of 80-300 mm and which can be set
at an optional angle to the horizontal plane of the
board. To facilitate the understanding and the comparison
with the other drawings figures, the floorboard, however,
is shown with its surface plane HP directed upwards.
20 Fig. 23a shows how the first tool with the tool position
TP1 makes a traditional tongue groove. The tool operates
in this case at a tool angle TAl which is 0 , i.e. paral-
lel with the horizontal plane. The axis of rotation RA.1
is perpendicular to HP. The undercut is made by means of
25 a second tool, where the position TP2 and the design of
the tool are such that the undercut 35 can be formed
without the tool affecting the shape of the lower lip 40.
In this case, the tool has an angle TA2 which is equal to
the angle of the locking surface 45 in the undercut 35.
30 This manufacturing method is possible by the locking
plane LP1 being located at such a distance from the joint
plane that the tool can be inserted into the previously
formed tongue groove. The thickness of the tool therefore
cannot exceed the distance between the two planes LP1 and
35 LP2, as discussed in connection with Figs 21a and 21b.
This manufacturing method is prior-art technique and does
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46
not constitute part of the manufacturing method according
to the present invention as will be described below.
Figs 24a, 24b show another variant of the invention.
This embodiment is characterised in that the joint system
is formed completely according to the basic principle of
inward angling about the upper joint edges as described
above. The locking surfaces 45, 65 and the lower support-
ing surfaces 50, 71 are in this embodiment plane, but
they can have a different shape. Cl and C2 are two circu-
lar arcs with their centre C at the upper end of adjoin-
ing joint edges 41, 61. The smaller circular arc Cl is
tangent to the lower contact point closest to the verti-
cal plane between the locking surfaces 45, 65 at the
point P4 which has the tangent TL1 corresponding to the
locking plane LP1. The locking surfaces 45, 65 have the
same inclination as this tangent. The greater circular
arc 62 is tangent to the upper contact point between the
lower supporting surfaces 50, 71 closest to the inner
part 48 of the tongue groove at the point P7, which has
the tangent TL2. The supporting surfaces 50, 71 have the
same inclination as this tangent.
All the contact points between the tongue 38 and the
upper lip 39 which are positioned between the point P4
and the vertical plane VP satisfy the condition that they
are positioned inside or on the circular arc Cl, while
all contact points which are positioned between P4 and
the inner part 48 of the tongue groove - in this embodi-
ment only the locking surfaces 45, 65 - satisfy the con-
dition that they are positioned on or outside Cl. The
corresponding conditions are satisfied for the contact
surfaces between the lower lip 40 and the tongue 38. All
contact points between the tongue 38 and the lower lip 40
which are positioned between the point P7 and the verti-
cal plane VP - in this case only the lower supporting
surfaces 50, 71 - are positioned on or outside the circu-
lar arc C2, while all contact points which are positioned
between the point P7 and the inner part 48 of the tongue
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47
groove, are positioned on or inside the circular arc C2.
In this embodiment there are no contact points between P7
and the inner part 48 of the tongue groove.
This embodiment is characterised in particular in
that all contact surfaces between the contact point P4
and the joint plane VP, in this case the point P5, and
the inner part 48 of the tongue groove, respectively, are
positioned inside and outside, respectively, the circular
arc Cl and thus not on the circular arc Cl. The same
applies to the contact point P7 where all contact points
between P7 and the vertical plane VP, in this case the
point P8, and the inner part 48 of the tongue groove,
respectively, are positioned outside and inside, respec-
tively, the circular arc C2 and thus not on the circular
arc C2. As is evident from the part indicated by broken
lines in Fig. 24a, the joint system can, if this condi-
tion is satisfied, be designed so that inward angling can
take place with clearance during essentially the entire
angular motion which can be terminated by the boards
being locked with a tight fit or with a press fit when
they have taken their final horizontal position. Thus,
the invention enables a combination of an inward angling
and upward angling without resistance and a locking with
high joint quality. If the lower supporting surfaces 71,
50 are made with a somewhat lower angle, a joint system
can be provided, where only the two above-mentioned
points P4 on the upper lip and P7 on the lower part of
the tongue are contact points between the tongue groove
36 and the tongue 38 during the entire inward angling
until final locking takes place, and during the entire
upward angling until the boards can be released from each
other. Locking with clearance or with only line contact
is a great advantage since the friction will be low and
the boards can easily be angled inward and angled upward
without parts of the system getting stuck and pinching
each other with a risk of the joint system being damaged.
A press fit especially in the vertical direction is very
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48
important for the strength. If there is play between the
engaging or supporting surfaces, the boards will, when
subjected to tensile load, slide along the locking sur-
faces until the lower engaging or supporting surfaces
have taken a position with a press fit. Thus a play will
result in both a joint gap and differences in level
between upper joint edges. As an example, it may be men-
tioned that with a tight fit or press fit, high strength
can be achieved if the locking surfaces have an angle of
about 40 to the surface plane HP and if the lower engag-
ing or supporting surfaces have an angle of about 15 to
the surface plane HP.
The locking plane LP1 has in Fig. 24a a locking
angle A to the horizontal plane HP of about 39 , while
the supporting plane TL2 along the supporting surfaces
50, 71 has a supporting angle VLA of about 14 . The dif-
ference in angle between LP1 and the supporting plane TL2
is 25 . A high locking angle and a great difference in
angle between locking angle and supporting angle should
be strived for since this results in a great horizontal
locking force. The locking surfaces and the supporting
surfaces can be made arcuate, stepped, with several
angles etc, but this makes manufacture difficult. As men-
tioned above, the locking surfaces may also constitute
upper supporting surfaces or be complements to separate
upper supporting surfaces.
Even if the locking surfaces and supporting sur-
faces have contact points that deviate somewhat from
these basic principles, they can be angled inward at
their upper joint edges if the joint system is adjust-
ed so that its contact points or surfaces are small in
relation to the floor thickness and so that the proper-
ties of the board material in the form of compression,
elongation and bending are used maximally in combination
with very small plays between the contact surfaces.
This can be used to increase the locking angle and the
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49
difference in angle between locking angle and supporting
angle.
The basic principle of inward angling thus shows
that the critical parts are the locking surfaces 45, 65
and the lower supporting surfaces 50, 71. It also shows
that the degree of freedom is great as regards designing
of the other parts, for instance the upper supporting
surfaces 43, 64, the guiding 44 of the locking groove,
the guiding 66 and the top surface 67 of the locking
element 8, the inner parts 48, 49 of the tongue groove
36 and the lower lip 40, the guiding and the outer part
51 of the lower lip as well as outer/lower parts 69, 70,
72 of the tongue. These should preferably deviate from
the shape of the two circular arcs Cl and C2, and between
all parts except the upper supporting surfaces 43, 64
there can be free spaces, so that these parts in the
locked position as well as during inward angling and
upward angling are not in contact with each other. This
facilitates manufacture significantly since these parts
can be formed without great tolerance requirements, and
it contributes to safe inward angling and upward angling
and also lower friction in connection with lateral dis-
placement of joined boards along the joint plane VP
(direction D3). By free spaces is meant joint parts that
do not have any functional meaning to prevent vertical or
horizontal displacement and displacement along the joint
edge in the locked position. Thus, loose wood fibres and
small deformable contact points should be considered
equivalent to free surfaces.
Angling about the upper joint edge can, as mentioned
above, be facilitated if the joint system is constructed
so that there can be a small play between above all said
locking surfaces 45, 65 if the joint edges of the boards
are pressed together. The construction play also facili-
tates lateral displacement in the locked position,
reduces the risk of creaking and gives greater degrees of
freedom in manufacture, allows inward angling with lock-
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ing surfaces that have a greater inclination than the
tangent LP1 and contribute to compensating for swelling
of upper joint edges. The play gives considerably smaller
joint gaps at the upper side of the boards and consider-
5 ably smaller vertical displacements than would a play
between the engaging or supporting surfaces, above all
owing to this play being small and also owing to the fact
that a sliding in the tensile-loaded position will follow
the angle of the lower supporting surface, i.e. an angle
10 which is essentially smaller than the locking angle. This
minimal play, if any, between the locking surfaces can
be very small, for instance only 0.01 mm. In the normal
joined position the play can be non-existent, i.e. 0, the
joint system can be constructed so that a play appears
15 only in maximal pressing together of the joint edges of
the boards. It has been found that also a greater play of
about 0.05 mm will result in a very high joint quality,
since the joint gap which is to be found in the surface
plane HP and which may arise in the tensile-loaded posi-
20 tion is hardly visible.
It should be pointed out that the joint system can
be constructed without any play between the locking sur-
faces.
Play and material compression between the locking
25 surfaces and bending of joint parts at the locking sur-
faces can easily be measured indirectly by the joint sys-
tem being subjected to tensile load and the joint gap at
the upper joint edges 41, 61 being measured at a prede-
termined load which is less than the strength of the
30 joint system. By strength is meant that the joint system
is not broken or does not snap out. A suitable tensile
load is about 50% of the strength. As a non-limiting
standard value, it may be mentioned that a long side
joint should normally have a strength exceeding 300 kg
35 per running meter of joint. Short side joints should have
still greater strength. A parquet floor with a suitable
joint system according to the invention can withstand a
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51
tensile load of 1000 kg per running meter of joint. A
high-quality joint system should have a joint gap at the
upper joint edges 41, 61 of about 0.1-0.2 mm when sub-
jected to tensile load with approximately half the maxi-
mum strength. The joint gap should decrease when the load
ceases. By varying the tensile load, the relationship
between construction play and material deformation can be
determined. In case of lower tensile load, the joint gap
is essentially a measure of the construction play. In
case of a higher load, the joint gap increases owing to
material deformation. The joint system can also be con-
structed with built-in initial stress and a press fit
between locking surfaces and supporting surfaces, so that
the above-mentioned joint gap is not visible in case of
the above-mentioned load. -
The geometry of the joint system, play between the
locking surfaces in combination with compression of the
material round the upper joint edges 41, 61 can also be
measured by the joint being sawn up transversely of the
joint edge. Since the joint system is manufactured with
linear machining, it will have the same profile along its
entire joint edge. The only exception is manufacturing
tolerances in the form of lack of parallelism owing to
the fact that the board can optionally be turned or dis-
placed vertically or horizontally as it passes different
milling tools in the machine. Normally seen, the two
samples from each joint edge, however, give a very
reliable picture of what the joint system looks like.
After grinding the samples and cleaning them of loose
fibres so that a sharp joint profile is to be seen,
they can be analysed as regards joint geometry, material
compression, bending etc. The two joint parts can, for
instance, be compressed by means of a force which is such
as not to damage the joint system, above all the upper
joint edges 41, 61. The play between the locking sur-
faces and the joint geometry can then be measured in a
measuring microscope with an accuracy of 0.01 mm or less
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according to equipment. If stable and modern machines are
used in manufacture, it is as a rule sufficient to mea-
sure the profile in two smaller areas of a floorboard to
determine the average play, joint geometry etc.
All measuring should take place when the floorboards
are conditioned at a normal relative humidity of about
450.
Also in this case, the locking element or the
upwardly directed portion 8 of the tongue has a guiding
part 66. The guiding part of the locking element com-
prises parts having an inclination which is lower than
the inclination of the locking surface and, in this case,
also the inclination of the tangent TL1. A suitable
degree of inclination of the tool that produces the lock-
ing surface 45 is indicated by TA2 which in this embodi-
ment is equal to the tangent TL1.
Also the locking surface 45 of the tongue groove has
a guiding part 44 which coacts with the guiding part 66
of the tongue during inward angling. Also this guiding
part 44 comprises parts that have a smaller inclination
than the locking surface.
In the front part of the lower lip 40, there is a
rounded guiding part 51, which coacts with the radius in
the lower part of the tongue in connection with the lower
engaging surface 71 at the point P7 and which facilitates
inward angling.
The lower lip 40 can be resilient. In connection
with inward angling, a small degree of compression can
also take place of the contact points between the lower
parts of the tongue 38 and the lower lip 40. As a rule,
this compression is significantly smaller than may be the
case for the locking surfaces since the lower lip 40 can
have considerably better resilience properties than the
upper lip 39 and the tongue 38, respectively. In connec-
tion with inwa.rd angling and upward angling, the lip can
thus be bent downwards. A bending capacity of merely one
tenth of a millimetre or somewhat more gives, together
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with material compression and small contact surfaces,
good chances of forming, for instance, the lower sup-
porting surfaces 50, 71, so that they can have an incli-
nation which is smaller than the tangent TL2 while at the
same time inward angling can easily be made. A flexible
lip should be combined with a relatively high locking
angle. If the locking angle is low, a large amount of the
tensile load will press the lip downward, which results
in undesirable joint gaps and differences in level
between the joint edges.
Both the tongue groove 36 and the tongue 38 have
guiding parts 42, 51 and 68, 70 which guide the tongue
into the groove and facilitate snapping-in and inward
angling.
Fig. 25 illustrates variants of the invention, where
the lower lip 40 is shorter than the upper lip 39 and
thus is positioned at a distance from the vertical
plane VP. The advantage is that there will be greater
degrees of freedom in designing the locking groove 45
with a high tool angle TA while at the same time rela-
tively large tools can be used. To facilitate snapping-in
by downward bending of the lower lip 40, the tongue
groove 36 has been made deeper than is required by the
space for the tip of the tongue 38. The dash-dotted joint
edge portion 4b shows how the parts of the system are
related to each other in connection with inward angling
about the upper joint edge, while the dashed joint edge
portion 4b shows how the parts of the system are related
to each other in connection with snapping-in of the
tongue into the tongue groove by displacement of the
joint edge portion 4b straight towards the joint edge
portion 4a.
Fig. 26 shows a further variant of the above-
mentioned basic principles. The joint system is here
formed with locking surfaces which are angled at 90
to the surface plane HP and which are considerably more
angled than the tangent TL1. Such a preferred locking
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54
system, however, is openable by upward angling by the
locking surfaces being extremely small and by the joint
locking essentially only by line contact. If the core is
hard, such a locking system can give high strength. The
design of the locking element and the locking surfaces
allows snapping-in with only a small degree of downward
bending of the lower lip, as indicated by means of dashed
lines.
Figs 27a-c show a laying method by inward angling.
To facilitate the description, one board is referred to
as groove board and the other as tongue board. In prac-
tice, the boards are identical. A possible laying method
involves that the tongue board lies flat on the subfloor
either as a loose board or joined with other boards on
one, two or three sides, depending on where in the laying
sequence/row it is positioned. The groove board is placed
with its upper lip 39 partly over the outer part of the
tongue 38, so that the upper joint edges are in contact
with each other. Then the groove board is turned down
towards the subfloor while being pressed against the
joint edge of the tongue board until final locking takes
place according to Fig. 27c.
The sides of floorboards sometimes have a certain
degree of bending. The groove board is then pressed
and turned downwards until parts of the upper lip 39 are
in contact with parts of the upwardly directed portion or
locking element 8 of the tongue and parts of the lower
lip 40 are in contact with parts of the lower part of
the tongue. In this manner, any bending of the sides can
be straightened, and then the boards can be angled to
their final position and locked.
Figs 27a-c show that the inward angling can take
place with clearance, or alternatively merely contact
between the upper part of the tongue groove and the
tongue or with line contact between the upper and lower
parts of the tongue and the tongue groove. Line contact
can in this embodiment arise at points P4 and P7. Inward
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angling can easily take place without considerable resis-
tance and can be terminated with a very close fit that
locks the floorboards in the final position with high
joint quality vertically and horizontally.
5 Summing up, the downward angling can in practice be
carried out as follows. The groove board is moved at an
angle towards the tongue board, the tongue groove being
passed over part of the tongue. The groove board is
pressed towards the tongue board and angled gradually
10 downwards using, for instance, compression in the centre
of the board and, after that, on both edges. When the
upper joint edges over the entire board are close to each
other or in contact with each other, and the board has
taken a certain angle to the subfloor, the final downward
15 angling can be made.
When the boards have been joined, they can be dis-
placed in the locked position in the joint direction,
i.e. parallel with the joint edge.
Figs 28a-c show how a corresponding laying can be
20 carried out by the tongue board being angled into groove
board.
Figs 29a-b show joining by snapping-in. When the
boards are moved towards each other horizontally, the
tongue is guided into the groove. During continued com-
25 pression, the lower lip 40 bends, and the locking element
8 snaps into the locking groove or the undercut 35. It
should be emphasised that the preferred joint system
shows the basic principles of snapping-in, where the
lower lip is flexible. The joint system must, of course,
30 be adjusted to the bending capacity of the material and
the depth of the tongue groove 36, the height of the
locking element 8 and the thickness of the lower lip 40
and should be dimensioned so that snapping-in is feas-
ible. The basic principles of a joint system according
35 to the invention which is more convenient for use in
materials with a lower degree of flexibility and bend-
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56
ability will be evident from the following description
and Fig. 34.
The described laying methods can be used optionally
on all four sides and be combined with each other. After
laying of one side, a lateral displacement usually takes
place in the locked position.
In some cases, for instance in connection with
inward angling of the short side as a first operation,
an upward angling of two boards usually takes place.
Fig. 30 shows a first board 1, and an upwardly angled
second board 2a and an upwardly angled new third board 2b
which on its short side is already joined with the second
board 2b. After the new board 2b has been laterally dis-
placed along the short side of the second board 2a in the
upwardly angled and short-side-locked position, the two
boards 2a and 2b can be angled down jointly and locked on
the long side to the first board 1. For this method to
function, it is required that the new board 2b can be
inserted with its tongue into the tongue groove when the
board is displaced parallel with the second board 2a and
when the second board 2a has a part of its tongue par-
tially inserted into the tongue groove and when its upper
joint edge is in contact with the upper joint edge of the
first board 1. Fig. 30 shows that the joint system can be
made with such a design of the tongue groove, tongue and
locking element that this is possible.
All laying methods require displacement in the lock-
ed position. One exception to lateral displacement in the
locked position is the case where several boards are
joined on their short sides, after which a whole row is
laid simultaneously. This is, however, not a rational
laying method.
Figs 31a, 31b show part of a floorboard with a com-
bination joint. The tongue groove 36 and the tongue 38
can be formed according to one of the embodiments above.
The groove board has on its underside a known strip 6
with a locking element 8b and a locking surface 10. The
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tongue side has a locking groove 35 according to a known
embodiment. In this embodiment, the locking element 8b
with its relatively large guiding part 9 will function
as an extra guiding during the first part of the inward
angling and significantly facilitates this first part of
the inward angling when positioning takes place and any
banana shape is straightened out. The locking element 8b
causes automatic positioning and compression of the
floorboards until the guiding part of the tongue is
engaged with the locking groove 35 and final locking can
take place. The laying is facilitated to a considerable
extent, and the joint will be very strong by coaction of
the two locking systems. This joint is very convenient
for joining of large floor surfaces particularly in
public rooms. In the shown example, the strip 6 has been
attached to the groove side, but it can also be attached
to the tongue side. The positioning of the strip 6 thus
is optional. Moreover, the joint can be both snapped in
and angled upwards and be laterally displaced in the
locked position.
Of course, this joint can be used optionally in dif-
ferent variants on both long and short side, and it can
be optionally combined with all joint variants described
here and with other known systems.
A convenient combination is a snap system on the
short side without an aluminium strip. This may in some
cases facilitate manufacture. A strip that is attached
after manufacture also has the advantage that it may also
constitute part of or even the entire lower lip 40. This
gives very great degrees of freedom for forming, with
cutting tools, for instance the upper lip 39 and forming
locking surfaces with high locking angles. The locking
system according to this embodiment can, of course, be
made snappable, and it can also be manufactured with an
optional width of the strip, for instance with a strip 6
that does not protrude outside the outer part of the
upper lip 39, as is the case in the embodiment according
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to Fig. 50. The strip need not be continuous over the
entire length of the joint but may consist of several
small portions which are attached with space in between
on both long side and short side.
The locking element 8b and its locking groove 35 can
be formed with different angles, heights and radii which
can be selected optionally, so that they either prevent
separation and/or facilitate inward angling or snapping-
in.
Figs 32a-d illustrate in four steps how inward
angling can be made. The broad strip 6 makes it possible
for the tongue 38 to be easily laid on the strip at the
beginning of the inward angling. The tongue can then, in
connection with downward angling, essentially automati-
cally slide into the tongue groove 36. The corresponding
laying can be made by the strip 6 being inserted under
the tongue board. All laying functions that have been
described above can also be used in floorboards with this
preferred combination system.
Figs 33 and 34 show a production-specific and opti-
mised joint system for above all a floorboard with a core
of wood. Fig. 33 shows how the long side can be formed.
In this case, the joint system is optimised with regard
to, above all, inward angling, upward angling and a small
amount of material waste. Fig. 34 shows how the short
side can be formed. In this case, the joint system is
optimised for snapping-in and high strength. The diffe-
rences are as follows. The tongue 38 and the locking ele-
ment of the short side 5a are longer, measured in the
horizontal plane. This gives a higher shear strength in
the locking element 8. The tongue groove 36 is deeper on
the short side 5b, which helps the lower lip to be bent
downwards to a greater extent. The locking element 8 is
on the short side 5a lower in the vertical direction,
which reduces the requirement for the downward bending of
the lower lip in connection with the snapping. The lock-
ing surfaces 45, 65 have a higher locking angle and the
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lower engaging surfaces have a lower angle. The guiding
parts of the long side 4a, 4b in the locking element and
the locking groove are greater for optimal guiding, while
at the same time the contact surface between the locking
surfaces is smaller since the strength requirements are
lower than for the short side. The joint systems on the
long and short side can consist of different materials or
material properties in upper lip, lower lip and tongue,
and these properties can be adjusted so that they contri-
bute to optimising the different properties that are
desired for long side and short side, respectively, with
regard to function and strength.
Fig. 35 shows in detail how the joint system of
the floorboard can be formed on the long side. The prin-
ciples here described can, of course, be used on both
long side and short side. Only the parts that have pre-
viously not been discussed in detail will now essentially
be described.
The locking surfaces 45, 65 have an angle HLA which
is greater than the tangent TL1. This gives a higher
horizontal locking force. This overbending should be
adjusted to the wood material of the core and optimis-
ed with regard to compression and flexural rigidity so
that inward angling and upward angling can still take
place. The contact surfaces of the locking surfaces
should be minimised and adjusted to the properties of
the core.
When the boards are joined, a small part, preferably
less than half the extent of the locking element in the
vertical direction, constitutes the contact surfaces of
the locking element 8 and the locking groove 14. The
major part constitutes rounded, inclined or bent guiding
parts which in the joined position and during inward
angling and upward angling are not in contact with each
other.
The inventor has discovered that very small contact
surfaces in relation to the floor thickness T between the
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locking surfaces 45, 65 of, for instance, a few tenths of
a millimetre can result in a very high locking force and
that this locking force can exceed the shear strength of
the locking element in the horizontal plane (i.e. the
5 surface plane HP). This can be used to provide locking
surfaces with an angle exceeding the tangent TL1.
In this case, the locking surfaces 45, 65 are plane
and parallel. This is advantageous especially as regards
the locking surface 55 of the locking groove. If the tool
10 is displaced parallel with the locking surface 45, this
will not affect the vertical distance to the joint plane
VP, and it is easier to provide a high joint quality. Of
course, small deviations from the plane form may give
equivalent results.
15 Correspondingly, the lower supporting surfaces 50,
71 have been made essentially plane and with an angle
VLA2 which in this case is greater than the tangent line
TL2 to the point P7 which is positioned on the supporting
surface 71 closest to the bottom of the tongue groove.
20 This causes inward angling with clearance during essen-
tially the entire angular motion. Also the supporting
surfaces 50, 71 are relatively small in relation to the
floor thickness T. These supporting surfaces can also be
made essentially plane. Plane supporting surfaces facili-
25 tate the manufacture according to the above described
principles.
The supporting surfaces 50, 71 can also be made with
angles that are smaller than the angle of inclination of
the tangent TL2. In this case, angling can take place
30 partly by means of a certain degree of material compres-
sion and downward bending of the lower lip 40. If the
lower supporting surfaces 50, 71 are small in relation
to the floor thickness T, the possibilities of forming
the surfaces with angles that are greater and smaller,
35 respectively, than the tangent TL1 and TL2, respectively,
increase.
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Fig. 36 shows upward angling of a board which has a
geometry according to Fig. 35 and whose locking surfaces
thus have a greater inclination than the tangent TL1 and
whose supporting surfaces have a smaller inclination than
the tangent TL2 while at the same time these surfaces are
relatively small. The overlap at the points P4 and P7 in
connection with inward angling and upward angling will
then be extremely small. The point P4 can be angled
depending on a combination of the material being com-
pressed at the upper joint edges Kl, K2 and at the point
P4, K3, K4 while at the same time the upper lip 39 and
the tongue 38 can bend in the direction B1 and B2 from
the contact point P4. The lower lip can bend downwards
away from the contact point P7 in the direction B3.
The upper supporting surfaces 43, 64 are preferably
perpendicular to the joint plane VP. The manufacture is
facilitated significantly if the upper and lower support-
ing surfaces are plane-parallel and preferably horizon-
tal.
Reference is once more made to Fig. 35. The circular
arc Cl shows, for instance, that the upper supporting
surfaces can be formed in many different ways inside this
circular arc Cl without this interfering with the possi-
bilities of angling and snapping. In the same way, the
circular arc C2 shows that the inner parts of the tongue
groove and the outer parts of the tongue according to the
previously preferred principles can be formed in many
different ways without this interfering with the possibi-
lities of angling and snapping.
The upper lip 39 is over its entire extent thicker
than the lower lip 40. This is advantageous from the
viewpoint of strength. Moreover, this is advantageous in
connection with parquet floors, which as a result can be
formed with a thicker surface layer of a hard kind of
wood.
S1-S5 indicate areas where joint surfaces on both
sides should not be in contact with each other at least
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in the joined position, but preferably also during inward
angling. A contact between the tongue and the tongue
groove in these areas S1-S5 contributes only marginally
to improving the locking in D1 direction and hardly at
all to improving the locking in the D2 direction. How-
ever, a contact prevents inwardly angling and lateral
displacement, causes unnecessary tolerance problems in
connection with manufacture and increases the risk of
creaking and undesired effects as the boards swell.
The tool angle TA, which in Fig. 38d is indicated by
TA4, forms the locking surface 44 of the undercut 35 and
operates with the same angle as the angle of the locking
surface, and the part of this tool which is positioned
inside the vertical plane towards the tongue groove has
a width perpendicular to the tool angle TA which is indi-
cated by TT. The angle TA and the width TT determine
partly the possibilities of forming the outer parts 52 of
the lower lip 40.
A plurality of ratios and angles are important for
an optimal manufacturing method, function, cost and
strength.
The extent of the contact surfaces should be mini-
mised. This reduces friction and facilitates displacement
in the locked position, inward angling and snapping in,
simplifies manufacture and reduces the risk of swelling
problems and creaking. In the preferred example, less
than 30% of the surface parts of the tongue 38 constitute
contact surfaces with the tongue groove 36. The contact
surfaces of the locking surfaces 65, 45 are in this embo-
diment only 2% of the floor thickness T, and the lower
supporting surfaces have a contact surface which is only
10% of the floor thickness T. As mentioned above, the
locking system has in this embodiment a plurality of
parts S1-S5 which constitute free surfaces without con-
tact with each other. The space between these free sur-
faces and the rest of the joint system can within the
scope of the invention be filled with glue, sealing
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agent, impregnation of different kinds, lubricant and
the like. By free surfaces is here meant the form of the
surfaces in the joint system that it obtains in connec-
tion with machining by means of the respective cutting
tools.
If the joint has a tight fit, the locking surfaces
65, 45 can prevent horizontal separation even when they
have an angle HLA to the horizontal plane HP which is
greater than zero. The tensile strength of the joint
system, however, increases significantly when this lock-
ing angle becomes greater and when there is a difference
in angle between the locking angle HLA of the locking
surfaces 45, 65 and the engaging angle VLA2 of the lower
supporting surfaces 50, 71, provided that this angle is
smaller. If high strength is not required, the locking
surfaces can be formed with low angles and small diffe-
rences in angle to the lower engaging surfaces.
For good joint quality in floating floors, the lock-
ing angle HLA and the difference in angle to lower sup-
porting surfaces HLA - VLA2 must as a rule be about 20 .
Still better strength is obtained if the locking angle
HLA and the difference in angle HLA-VLA2 is, for instance
. In the preferred example according to Fig. 35, the
locking angle is 50 and the angle of the supporting sur-
25 faces 20 . As shown in previous embodiments, joint sys-
tems according to the invention can be formed with still
greater locking angles and differences in angle.
A large number of tests have been made with diffe-
rent locking angles and engaging'angles. These tests
30 prove that it is possible to form a high-quality joint
system with locking angles between 40 and 55 and with
supporting surface angles between 0 and 25 . It should be
emphasised that also other ratios can result in a
satisfactory function.
The horizontal extent PA of the tongue should exceed
1/3 of the thickness T of the floorboard, and it should
preferably be about 0.5 * T. As a rule, this is necessary
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for a strong locking element 8 with a guiding part to be
formed and for sufficient material to be available in the
upper lip 39 between the locking surface 65 and the ver-
tical plane VP.
The horizontal extent PA of the tongue 38 should be
divided into two essentially equal parts PAl and PA2,
where PAl should constitute the locking element and the
major part of PA2 should constitute the supporting sur-
face 64. The horizontal extent PAl of the locking element
should not be less than 0.2 times the floor thickness.
The upper supporting surface 64 should not be too great,
above all on the long side of the floorboard. Otherwise,
the friction in connection with lateral displacement can
be too high. To enable rational manufacture, the depth
G of the tongue groove should be 2% deeper than the pro-
jection of the tongue PA from the joint plane VP. The
smallest distance of the upper lip to the floor surface
adjacent to the locking groove 35 should be greater than
the smallest distance of the lower lip between the lower
supporting surface 71 and the rear side of the floor-
board. The tool width TT should exceed 0.1 times the
floor thickness T.
Figs 37a-c illustrate a floorboard according to the
invention. This embodiment shows specifically that the
joint system on the short side may consist of different
materials and material combinations 30b and 30c and that
these can also differ from the joint material 30 of the
long side. For instance, the tongue groove part 36 of the
short sides may consist of a harder and more flexible
wood material than, for instance, the tongue part 38
which can be hard and rigid and have other properties
than the core of the long side. On the short side with
the tongue groove 36, it is possible to select, for
instance, a kind of wood 30b which is more flexible than
the kind of wood 30c on the other short side where the
tongue is formed. This is particularly convenient in
parquet floors with a lamellar core where the upper and
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lower side consist of different kinds of wood and the
core consists of blocks that have been glued together.
This construction gives great possibilities of varying
the composition of materials in order to optimise func-
5 tion, strength and production costs.
It is also possible to vary the material along the
length of one side. Thus, for instance the blocks that
are positioned between the two short sides can be of
different kinds of wood or materials, so that some of
10 them can be selected with regard to their contributing
with suitable properties which improve laying, strength
etc. Different properties can also be obtained with dif-
ferent fibre orientation on long and short side, and also
plastic materials can be used on the short sides and, for
15 instance, on different parts of the long side. If the
floorboard or parts of its core consist of, for example,
plywood with several layers, these layers can be selected
so that the upper lip, the tongue and the lower lip on
both long side and short side can all have parts with a
20 different composition of materials, fibre orientation
etc. which can give different properties as regards
strength, flexibility, machinability etc.
Figs 38a-d show a manufacturing method according to
the present invention. In the shown embodiment, the manu-
25 facture of the joint edge and the tongue groove occurs
in four steps. The tools used have a tool diameter which
exceeds the floor thickness. The tools are used to form
an undercut groove with a high locking angle in a tongue
groove with a lower lip, which extends beyond the under-
30 cut groove.
In order to simplify the understanding and the com-
parison with previously described joint systems, the
edges of the boards are illustrated with the floor sur-
face directed upwards. Normally, the boards are, however,
35 positioned with their surface directed downwards during
machining.
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The first tool TP1 is a roughing cutter which ope-
rates at an angle TA1 to the horizontal plane. The second
tool TP2 can operate horizontally and forms the upper and
lower supporting surfaces. The third tool TA3 can operate
essentially vertically but also at an angle and forms the
upper joint edge.
The critical tool is the tool TP4 which forms the
outer part of the locking groove and its locking surface.
TA4 corresponds to TA in Fig. 35. As is evident from
Fig. 38d, this tool removes only a minimum amount of the
material and forms essentially the locking surface with
a high angle. For the tool not to break, it should be
formed with a wide part which is extended outside the
vertical plane. Moreover, the amount of material to be
removed should be as small as possible to reduce wear
and strain on the tool. This is achieved with a suitable
angle and design of the roughing cutter TP1.
Thus this manufacturing method is characterised
especially in that it requires at least two cutting tools
which operate at two different angles to form an undercut
locking groove 35 in the upper part of the tongue groove
36. The tongue groove can be made using still more tools,
the tools being used in a different order.
The description is now aimed in detail at the method
of forming a tongue groove 36 in a floorboard, which has
an upper side 2 in a surface plane HP and a joint edge
portion 4a having a joint plane VP directed perpendicu-
lar to the upper side. The tongue groove extends from
the joint plane 4a and is defined by two lips 39, 40 each
having a free outer end. In at least one lip, the tongue
groove has an undercut 35 which comprises a locking sur-
face 45 and is positioned further away from the joint
plane VP than is the free outer end 52 of the other lip.
According to the method, machining is carried out by
means of a plurality of rotating cutting tools which have
a larger diameter than the thickness T of the floorboard.
In the method, the cutting tools and the floorboard are
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made to perform a relative motion relative to each other
and parallel to the joint edge of the floorboard. What
characterises the method is 1) that the undercut is form-
ed by means of at least two such cutting tools, which
have their rotatary shaft inclined at different angles
to the upper side 2 of the floorboard; 2) that a first
of these tools is driven to form portions of the undercut
further away from the joint plane VP than the locking
surface 45 of the intended undercut; and 3) that a second
of these tools is driven to form the locking surface 45
of the undercut. The first of these tools is driven with
its rotary shaft set at a greater angle to the upper side
2 of the floorboard than is said second of these tools.
The lower lip 40 can be formed so as to extend beyond the
joint plane VP. The lower lip 40 can also be formed so
as to extend to the joint plane VP. Alternatively, the
lower lip 40 can be formed so as to end at a distance
from the joint plane VP.
The first of the tools can, according to an embodi-
ment, be driven with its rotary shaft set at an angle of
at most 85 to the surface plane HP. The second of the
tools can, according to an embodiment, be driven with
its rotary shaft set at an angle of at most 60 to the
surface plane HP. Moreover the tools can be caused to
engage the floorboard in order in dependence on the angle
of their rotary shaft to the surface plane HP, so that
tools with a greater angle of the rotary shaft are caused
to machine the floorboard before tools with a smaller
angle of the rotary shaft.
Moreover, a third of the tools can be driven to form
the lower parts of the tongue groove 36. This third tool
can be brought into contact with the floorboard between
said first and said second of the tools. The third tool
can further be driven with its rotary shaft set at an
angle of about 90 to the surface plane HP.
Further the first of the tools can be driven to
machine a broader surface portion of the joint edge por-
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tion 4a of the floorboard than said second of the tools.
The second of the tools can be formed so that its sur-
face facing the surface plane HP is profiled for reduc-
tion of the thickness of the tool, seen parallel with the
rotary shaft, within the radially outer portions of the
tool. Moreover, at least three of the tools can be driven
with different settings of their rotary shaft to form the
undercut parts of the tongue groove. The tools can be
used to machine a floorboard of wood or wood-fibre-based
material.
Fig. 39 shows how a joint system can be formed to
enable compensation for swelling. Since the relative
humidity increases in the change between cold and warm
weather, the surface layer 32 swells and the floorboards
4a and 4b are pressed apart. If the joint has no flexi-
bility, the joint edges 41 and 61 can be crushed, or
the locking element 8 can be broken. This problem can
be solved by the joint system being constructed so as to
obtain the following properties which each separately and
in combination contribute to a reduction of the problem.
The joint system can be formed so that the floor-
boards can have a small play when the joint edges are
pressed together horizontally, for instance, in connec-
tion with production and at normal relative humidity. A
play of a few hundredths of a millimetre contributes to a
reduction of the problem. A negative play, i.e. initial
stress, can give the opposite effect.
If the contact surface between the locking surfaces
45, 65 is small, the joint system can be formed so that
the locking surfaces are more easily compressed than the
upper joint edges 41, 61. The locking element 8 can be
formed with a grove 64a between the locking surface and
the upper horizontal supporting surface 64. With a suit-
able design of the tongue 38 and the locking element 8,
the outer part 69 of the tongue can be bent outwards to
the inner part 48 of the tongue groove and operate as a
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resilient element in connection with swelling and shrink-
ing of the surface layers.
In this embodiment, the lower supporting surfaces of
the joint system are formed parallel with the horizontal
plane for maximum locking vertically. It is also possible
to obtain expansibility by applying a compressible mate-
rial between, for instance, the two locking surfaces 45,
65 or selecting compressible materials as materials for
the tongue or groove part.
Fig. 40 shows a joint system according to the inven-
tion which has been optimised for high rigidity in the
tongue 38. In this case, the outer part of the tongue is
in contact with the inner part of the tongue groove. If
this contact surface is small and if the contact occurs
without very great compression, the joint system can be
displaceable in the locked position.
Fig. 41 shows a joint system where the lower sup-
porting surfaces 50, 71 have two angles. The portions
of the supporting surfaces outside the joint plane are
parallel with the horizontal plane. Inside the joint
plane closest to the inner part of the tongue groove,
they have an angle corresponding to the tangent to the
circular arc 32 which is tangent to the innermost edge
of the supporting surface parts engaging each other. The
locking surfaces have a relatively low locking angle. The
strength can still be sufficient since the lower lip 40
can be made hard and rigid and since the difference in
angle is great to the parallel part of the lower support-
ing surfaces 50, 71. In this embodiment, the locking sur-
faces 45, 65 also serve as upper supporting surfaces. The
joint system has no upper supporting surfaces in addition
to the locking surfaces which thus also prevent vertical
separation.
Figs 42a and 42b show a joint system which is con-
venient for short side locking and which can have high
tensile strength also in softer materials since the lock-
ing element 8 has a large horizontal shear-absorbing sur-
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face. The tongue 38 has a lower part which is positioned
outside the circular arc C2 and which thus does not fol-
low the above-described basic principle of inward angl-
ing. As is apparent from Fig. 42b, the joint system can
5 still be released by upward angling about the upper joint
edges since the locking element 8 of the tongue 38, after
the first upward angling operation has been carried out,
can leave the tongue groove by being pulled out horizon-
tally. The previously described principles for inward
10 angling and upward angling about upper joint edges should
thus be satisfied to enable upward angling until the
joint system can be released in some other manner by,
for instance, being pulled out or in combination with
snapping out when the lower lip 40 is being bent.
15 Figs 43a-c show the basic principle of how the lower
part of the tongue is to be formed in relation to the
lower lip 40 to facilitate horizontal snapping-in accord-
ing to the invention in a joint system with locking
grooves in a rigid upper lip 39 and with a flexible lower
20 lip 40. In this embodiment, the upper lip 39 is signi-
ficantly more rigid, inter alia owing to the fact that it
may be thicker or that it may consist of harder and more
rigid materials. The lower lip 40 can be thinner and
softer, and in connection with snapping-in the essential
25 bending will therefore take place in the lower lip 40.
Snapping-in can be significantly facilitated, among other
things, by the maximal bending of the lower lip 40 being
limited as far as possible. Fig. 43a shows that the bend-
ing of the lower lip 40 will increase to a maximal bend-
30 ing level B1 which is characterised by the tongue 38
being inserted so far into the tongue groove 36 that the
rounded guiding parts will come into contact with each
other. When the tongue 38 is inserted still more, the
lower lip 49 will be bent backwards until snapping-in is
35 terminated and the locking element 8 is fully inserted in
its final position in the locking groove 35. The lower
and front part 49 of the tongue 38 should be designed so
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as not to bend down the lower lip 40 which instead should
be forced downwards by the lower supporting surface 50.
This part 49 of the tongue should have a shape which
either touches or goes clear of the maximum bending level
of the lower lip 40 when this lower lip 40 is bent round
the outer part of the lower engaging surface 50 of the
tongue 38. If the tongue 38 has a shape which in this
position overlaps the lower lip 40, indicated by the
dashed line 49b, the bending B2 according to Fig. 43b can
be significantly greater. This may cause great friction
in connection with snapping-in and a risk of the joint
being damaged. Fig. 43c shows that the maximum bending
can be limited by the tongue groove 36 and the tongue 38
being designed in such manner that there is a space S4
between the lower and outer part 49 of the tongue and the
lower lip 40.
Horizontal snapping-in is as a rule used in connec-
tion with snapping-in of the short side after locking of
the long side. When snapping in the long side, it is also
possible to snap the joint system according to the inven-
tion with one board in a slightly upwardly angled posi-
tion. This upwardly angled snap position is shown in
Fig. 44. Only a small bending B3 of the lower lip 40 is
required for the guiding part 66 of the locking element
to come into contact with the guiding part 44 of the
locking groove, so that the locking element can then by
downward angling be inserted into the locking groove 35.
Figs 45-50 show different variants of the invention
which can be used on the long or short side and which can
be manufactured using large rotating cutting tools. With
modern manufacturing technology it is possible to form
according to the invention complicated shapes by machin-
ing in board materials at a low cost. It should be point-
ed out that most of the shown geometries in these and
previously preferred figures can, of course, be formed,
for example, by extrusion, but this method is usually
considerably more expensive than machining and is not
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convenient for forming of most board materials that are
normally used in floors.
Figs 45a and 45b show a locking system according to
the invention where the outer part of the tongue 38 has
been formed so as to be bendable. This bendability has
been obtained by the tip of the tongue being split.
During snapping-in, the lower lip 40 bends downwards and
the outer lower part of the tongue 38 bends upwards.
Figs 46a and 46b show a locking system according to
the invention with a split tongue. During snapping-in,
the two parts of the tongue bend towards each other while
at the same time the two lips bend away from each other.
These two joint systems are such as to allow angling
inwards and outwards, respectively, for locking and dis-
mounting.
Figs 47a and 47b show a combination joint where a
separate part 40b constitutes an extended part of the
lower lip and where this part can be resilient. The joint
system is angleable. The lower lip, which constitutes
part of the core, is formed with its supporting surface
in such a manner that snapping-in can take place without
this lip needing to be bent. Merely the extended separate
part, which can be made of aluminium sheet, is resilient.
The joint system can also be formed so that both parts of
the lip are resilient.
Figs 48a and 48b show snapping-in of a combination
joint with a lower lip consisting of two parts, where
merely the separate lip constitutes the supporting sur-
face. This joint system can be used, for instance, on the
short side together with some other joint system accord-
ing to the invention. The advantage of this joint system
is that, for instance, the locking groove 35 can be form-
ed with great degrees of freedom rationally and using
large cutting tools. After the machining, the outer lip
40b is attached, and its shape does not affect the possi-
bilities of machining. The outer lip 40b is resilient and
has in this embodiment no locking element. Another advan-
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tage is that the joint system enables joining of extreme-
ly thin core materials since the lower lip can be made
very thin. The core material can be, for instance, a thin
compact laminate, and the upper and the lower layer can
be relatively thick layers of e.g. cork or soft plastic
material, which can give a soft and sound-absorbing
floor. Using this technology, it is possible to join core
materials having a thickness of about 2 mm compared with
normal core materials which as a rule are not thinner
than 7 mm. The saving in thickness that can be achieved
can be used to increase the thickness of the other
layers. It is obvious that this joint can be used also
in thicker materials.
Figs 49 and 50 show two variants of combination
joints which can be used, for example, in the short side
in combination with other preferred systems. The combina-
tion joint according to Fig. 49 can be made in an embodi-
ment where the strip constitutes an extended resilient
part of the tongue, and the system will then have a func-
tion similar to the one in Fig. 45. Fig. 50 shows that
this combination joint can be formed with a locking ele-
ment 8b in the outer lower lip 40b which is positioned
inside the joint plane.
Figs. 51a-f show a laying method which is according
to the invention and which can be used to join floor-
boards by a combination of horizontal bringing-together,
upward angling, snapping in the upwardly angled position
and downward angling. This laying method can be used for
floorboards according to the invention, but it can also
be used on optional mechanical joint systems in floors
having such properties that the laying method can be
applied. To simplify the description, the laying method
is shown by one board, referred to as the groove board,
being joined with the other board, referred to as the
tongue board. The boards are in practice identical. It is
obvious that the entire laying sequence can also be car-
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ried out by the tongue side being joined with the groove
side in the same way.
A tongue board 4a with a tongue 38 and a groove
board 4b with a tongue groove 36 are in the starting
position lying flat on a subfloor according to Fig. 51a.
The tongue 38 and the tongue groove 36 have locking means
which present vertical and horizontal separation. Sub-
sequently the groove board 4b is displaced horizontally
in the direction Fl towards the tongue board 4a until
the tongue 38 is in contact with the tongue groove 36
and until the upper and lower parts of the tongue are
partially inserted into the tongue groove according to
Fig. 51b. This first operation forces the joint edge
portions of the boards to take the same relative verti-
cal position over the entire longitudinal extent of the
board, and any differences in arcuate shape will there-
fore be straightened out.
If the groove board is moved towards the tongue
board, the joint edge portion of the groove board will be
slightly raised in this position. The groove board 4b is
then angled upwards with an angular motion Sl while at
the same time it is held in contact with the tongue board
or alternatively is pressed in the direction Fl towards
the tongue board 4a according to Fig. 51c. When the
groove board 4b reaches an angle SA to the subfloor which
corresponds to an upwardly angled snap position, accord-
ing to the above description and as shown in Fig. 44, the
groove board 4b can be moved towards the tongue board 4a
so that the upper joint edges 41, 61 come into contact
with each other and so that the locking means of the
tongue are partially inserted into the locking means of
the tongue groove by a snap function.
This snap function in the upwardly angled position
is characterised in that the outer parts of the tongue
groove widen and spring back. The widening is essentially
smaller than is required in connection with snapping in
in the horizontal position. The snap angle SA is depen-
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dent on the force by which the boards are pressed towards
each other in connection with upward angling of the
groove board 4b. If the press force in the direction Fl
is high, the boards will snap in at a lower angle SA than
5 if the force is low. The snapping-in position is also
characterised in that the guiding parts of the locking
means are in contact with each other so that they can
perform their snapping-in function. If the boards are
banana-shaped, they will be straightened out and locked
10 in connection with the snapping-in. The groove board 4b
can now, with an angular motion S2 combined with pressing
towards the joint edge, be angled downwards according to
Fig. 51e and locked against the tongue board in its final
position. This is illustrated in Fig. 51f.
15 Depending on the construction of the joint, it is
possible to determine with great accuracy the snap angle
SA which gives the best function with regard to the
requirement that the snapping-in should take place with a
reasonable amount of force and that the guiding parts of
20 the locking means should be in such engagement that they
can hold together any banana shape, so that a final lock-
ing can take place without any risk of the joint system
being damaged.
The floorboards can according to the preferred lay-
25 ing method be installed without any actual aids. In some
cases, the installation can be facilitated if it is car-
ried out with suitable aids according to Figs 52a and
52b. A preferred aid according to the present invention
can be a striking or pressing block 80 which is designed
30 so as to have a front and lower part 81 which angles the
groove board upwards when it is inserted under the edge
portion of the floorboard. It has an upper abutment edge
82 which in the upwardly angled position is in contact
with the edge portion of the groove board. When the
35 striking block 80 has been inserted under the groove
board so that the abutment edge 82 is in contact with the
floorboard, the groove board will have the predetermined
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snap angle. The tongue groove of the groove board 4a can
now be snapped together with the tongue of the tongue
board by pressing or striking against the striking block.
Of course, the striking block can be moved to different
parts of the board. It is obvious that this can take
place in combination with other pressing against the
other parts of the board, using a plurality of striking
blocks and using different types of aids which give a
similar result where, for instance, one aid angles the
board up to the snapping-in angle and another is used for
pressing together. The same method can be used if instead
one wants to angle up the groove side of the new board
and join it with the tongue side of the previously laid
board.
The description will now be aimed at different
aspects of a tool for laying of floorboards. Such a tool
for laying of floorboards by interconnecting a tongue and
groove joint thereof can be designed as a block 80 with
an engaging surface 82 for engaging a joint edge 4a, 4b
of the joint edge portion of the floorboard. The tool can
be formed as a wedge for insertion under the floorboard
and have its engaging surface 82 arranged close to the
thick end of the wedge. The engaging surface 82 of the
tool can be concavely curved for at least partial enclo-
sure of the joint edge 4a, 4b of the floorboard. Moreover
the wedge angle S1 of the wedge and the position of the
engaging surface 82 on the thick portion of the wedge can
be adjusted to obtain a predetermined lifting angle of a
floorboard when it is being lifted with the wedge 80 and
the joint edge of the floorboard contacts the engaging
surface 82. The abutment surface 82 of the wedge 80 can
be formed to abut against a joint edge portion 4b which
has a tongue 38 directed obliquely upwards for joining an
undercut tongue groove 36 formed at the opposite joint
edge portion 4a of the floorboard with the tongue 38 of a
previously laid floorboard. Alternatively, the abutment
surface 82 of the wedge can be formed to abut against a
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joint edge portion 4a, which has an undercut groove 36,
for joining a tongue 38 directed obliquely upwards and
formed at the opposite joint edge portion 4b of the
floorboard.
The tool described above can be used for mechanical
joining of floorboards by lifting one floorboard rela-
tive to another and joining and locking of mechanical
locking systems of the floorboards. The tool can also be
used for mechanical joining of such a floorboard with
another such floorboard by snapping together the mecha-
nical locking systems of the floorboards while the floor-
board is in its lifted state. Furthermore the tool can
be used so that the engaging surface 82 of the wedge is
made to abut against a joint edge portion 4b which has
a tongue 38 directed obliquely upwards for joining an
undercut groove 36 formed at the opposite joint edge por-
tion 4a of the floorboard with the tongue 38 of a pre-
viously laid floorboard. Alternatively the tool can be
used so that the engaging surface 82 of the wedge is made
to abut against a joint edge portion 4a which has an
undercut groove 36, for joining a tongue 38 which is
directed obliquely upwards and formed at the opposite
joint edge portion 4b of the floorboard with the undercut
groove 38 of a previously laid floorboard.
Fig. 53 shows that the boards 2a and 2b, after being
joined with adjoining boards along the long side edge,
can be displaced in the locked position in the direction
F2 so that joining of the other two sides can take place
by a horizontal snapping together.
Snapping-in in the upwardly angled position can take
place of long sides as well as short sides. If the short
side of one board has first been joined, its long side
can also be snapped in the upwardly angled position by
this board with its locked short being angled up so that
it takes its snap angle. Subsequently, snapping-in takes
place in the upwardly angled position while at the same
time displacement in the locked position takes place
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along the short side. After snapping-in, the board is
angled down and it is locked on both long side and short
side.
Moreover, Figs 53 and 54 describe a problem which
can arise in connection with snapping-in of two short
sides of two boards 2a and 2b which have already been
joined on their long sides with another first board 1.
When the floorboard 2a is to snap into the floorboard 2b,
the inner corner portions 91 and 92, closest to the long
side of the first board 1, are located in the same plane.
This is due to the fact that the two boards 2a and 2b on
their respective long sides are joined to the same floor-
board 1. According to Fig. 54b, which shows the section
C3-C4, the tongue 38 cannot be inserted into the tongue
groove 36 to begin the downward bending of the lower lip
40. In the outer corner portions 93, 94 on the other long
side, in the section C1-C2 shown in Fig. 54a, the tongue
38 can be inserted into the groove 36 to begin the down-
ward bending of the lower lip 40 by the board 2b being
automatically angled up corresponding to the height of
the locking element 8.
Thus the inventor has discovered that there can be
problems in connection with snapping-in of inner corner
portions in lateral displacement in the same plane and
that these problems may cause a high snapping-in resis-
tance and a risk of cracking in the joint system. The
problem can be solved by a suitable joint design and
choice of materials which enable material deformation
bending in a plurality of joint portions.
When snapping-in such a specially designed joint
system, the following takes place. In lateral displace-
ment, the outer guiding parts 42, 68 of the tongue and
the upper lip coact and force the locking element 8 of
the tongue under the outer part of the upper lip 39. The
tongue bends downward and the upper lip bends upward.
This is indicated by arrows in Fig. 54b. The corner por-
tion 92 in Fig. 53 is pressed upward by the lower lip
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79
40 on the long side of the board 2b being bent and the
corner portion 91 being pressed downward by the upper lip
on the long side of the board 2a being bent upward. The
joint system should be constructed so that the sum of
these four deformations is so great that the locking
element can slide along the upper lip and snap into the
locking groove. It is known that it should be possible
for the tongue groove 36 to widen in connection with
snapping-in. However, it is not known that it may be an
advantage if the tongue, which normally should be rigid,
should also be designed so as to be able to bend in con-
nection with snapping-in. Such an embodiment is shown in
Fig. 55. A groove or the like 63 can be made at the upper
and inner part of the tongue inside the vertical plane
VP. The entire extent PB of the tongue from its inner
part to its outer part can be extended, and it can, for
instance, be made greater than half the floor thickness
T.
Figs 56 and 57 show how the parts of the joint sys-
tem bend in connection with snapping-in at the inner
corner portion 91, 92 (Fig. 57) and the outer corner por-
tion 93, 94 (Fig. 56) of two floorboards 2a and 2b. To
simplify manufacture, it is required that only the thin
lip and the tongue bend. In practice, of course all parts
that are subjected to pressure will be compressed and
bent to a varying degree depending on thickness, bendabi-
lity, composition of materials etc.
Figs 56a and 57a show the position when the edges of
the boards come into contact with each other. The joint
system is constructed in such manner that even in this
position, the outermost tip of the tongue 38 will be
located inside the outer part of the lower lip 40. When
the boards are moved further towards each other, the
tongue 38 in the inner corner 91, 92 will press the board
2b upward according to Figs 56b, 57b. The tongue will
bend downward and the board 2b at the outer corner 93, 94
will be angled upward. Fig. 57c shows that the tongue 38
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at the inner corner 91, 92 will be bent downward. At the
outer corner 93, 94 according to Fig. 56c, the tongue 38
is bent upward and the lower lip 40 is bent downward.
According to Figs 56d, 57d, this bending continues when
5 the boards are moved further towards each other, and now
also the lower lip 40 is bent at the inner corner 91, 92
according to Fig. 57d. Figs 56e, 57e show the snapped-in
position. Snapping-in can thus be facilitated signi-
ficantly if the tongue 38 is bendable and if the outer
10 part of the tongue 38 is positioned inside the outer part
of the lower lip 40 when tongue and groove come into con-
tact with each other as the boards are located in the
same plane in connection with snapping-in that takes
place after the floorboard has already been locked along
15 its two other sides.
Several variants can exist within the scope of the
invention. The inventor has manufactured and evaluated
a large number of variants where the different parts of
the joint system have been manufactured with different
20 widths, lengths, thicknesses, angles and radii of a num-
ber of different board materials and of homogeneous plas-
tic and wooden panels. All joint systems have been tested
in a position turned upside-down and with snapping and
angling of groove and tongue boards relative to each
25 other and with different combinations of the systems here
described and also prior-art systems on long side and
short side. Locking systems have been manufactured where
locking surfaces are also upper engaging surfaces, where
the tongue and groove have had a plurality of locking
30 elements and locking grooves, and where also the lower
lip and the lower part of the tongue have been formed
with horizontal locking means in the form of locking ele-
ment and locking groove.
