Note: Descriptions are shown in the official language in which they were submitted.
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DESCRIPTION
Nail, in particular for use in a nail setting tool
The present invention relates to a nail, in particular for use in a nail
setting tool,
which consists of a predominantly lignocellulosic material and has a nail
shank
at the front end of which a nail tip in the form of a conical round tip is
provided,
and at the rear end region of which a head region is formed. Furthermore, the
invention relates to a nail strip comprising a plurality of such nails which
are in-
serted into corresponding openings of a punched tape.
Nails have been known for a long time as connection means. They are mainly
made of metal, e.g. steel, aluminium, copper, etc. However, metal nails have
disadvantages. Despite corrosion protection measures such as galvanizing,
is steel nails tend to rust under unfavourable conditions, especially when
acidic
conditions prevail in the nailed material. This applies in particular to
tannin-rich
woods, which are used outdoors because of their durability, e.g. on facades
and
terraces. Weathering can cause unwanted dark to black discolouration of the
nail areas. A remedy by using stainless steel grades is possible but very
costly.
A further disadvantage is that the recycling of wood products interspersed
with
steel nails is expensive.
For this reason, nails made of wood or woody plant material such as bamboo
are used as an alternative. For a long time such wooden nails could only be
used if the substrate to be nailed was previously provided with a hole into
which
the nail was driven. Recent developments, however, allow nails made of wood
or wood-like, predominantly lignocellulosic materials to be inserted directly
into
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wood with the aid of nail setting tools such as pneumatic nailers without
pre-drilling the wood material. Reference should be made in particular to WO
2016/1809001 A of the applicant, from which a nail strip for use in a nail
setting
tool is known, the nails of which consist of wood or wood-based materials and
are connected to one another by connecting means, which are automatically
sheared off when the nails are set. The nail tip of the nail is conical in
shape,
whereby the ratio of the length of the nail tip to the smallest thickness of
the nail
shank is between 1.5 and 3.
m It has been shown that this nail tip formation can lead to splitting of
the compo-
nents to be joined when the nails are set, if these consist of anisotropic
building
materials such as wood. Another disadvantage is that the production of the
nail
strips by pressing and/or milling is laborious.
The task of the present invention is therefore to provide a nail of the type
men-
tioned above that can also be driven into wood-based materials without the
risk
of splitting them.
This task is solved by a nail of the type mentioned above having a tip angle
of
the nail tip > 40 . The tip angle of the nail tip is preferably in the range
of 45
and 60 , with an appropriate angle of 45 or 60 . However, larger angles such
as 90 are also possible.
It has been shown that nails having tip angles in the indicated ranges and in
par-
ticular greater than 50 have a significantly lower splitting effect on nailed
com-
ponents than nails with a tip angle smaller than 20 , for example.
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Although nails made of woody plant material have an increased pull-out re-
sistance compared to those made of steel of the same dimensions and therefore
do not require a head in most cases, there are applications in which not only
the
pull-out resistance but also the pull-through resistance is important. In
order to
.. increase the pull-through resistance, but to maintain the production
advantages
of pin-like nails compared to nails with a head, an embodiment of the
invention
provides that the head area is thickened relative to the nail shank and widens
continuously, in particular towards the free end of the nail.
Likewise, at least one recess extending in the axial direction of the nail
shank
may be provided in the upper end face of the head region, which recess is de-
signed such that a wedge can be driven axially into it in order to press the
mate-
rial webs of the head region present adjacent to the recess outwards. Expedi-
ently the at least one recess is slot-shaped and penetrates the head area from
one edge area to the opposite edge area. In particular, only a single slit-
shaped
recess is provided, which passes through the head area centrally and cuts the
longitudinal axis of the nail shank.
In this embodiment, a wedge is driven axially into the recess after a nail has
been driven or driven into a substrate, so that the material webs adjacent to
the
recess are pressed apart. This causes the entire head area to be deformed
outwards, resulting in increased contact pressure against the substrate
material.
If this is soft enough, the substrate material is even compressed. In this
case the
head region and the corresponding section receive a slight cone shape similar
to
that of a screw with a countersunk head through the nail channel section
formed
in the substrate material. The higher contact forces in the head area and the
conical shape significantly increase the pull-through resistance of the nails.
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The depth of the recesses/slits can be selected variably, but should be dimen-
sioned so that the adjacent material webs of the head region can be
sufficiently
pressed apart. For this purpose, according to an embodiment of the invention,
it
is provided that the recess extends from the upper end face of the head region
of the nail over an axial length of at least 3 mm, in particular at least 4 mm
and
preferably at least 5 mm into the head region.
In a further embodiment of the invention, it is intended that several
longitudinal
io grooves running parallel to each other in the longitudinal direction of
the nail
shank, preferably parallel to the longitudinal axis of the nail shank, are
formed in
the outer circumferential surface of the nail shank. The longitudinal grooves
can
extend over the entire length of the nail shank and be evenly distributed
along
the circumference of the nail shank. The shape of the longitudinal grooves can
be freely chosen. However, according to one embodiment of the invention, it is
intended that they are in the form of notches with an approximately triangular
cross-section.
Because the cylindrical shank is not smooth, but ribbed with a star-shaped
cross-section, the pull-out resistance of the nails is further increased.
The nail may consist of wood and/or a wood material, in particular an
organically
bonded wood material, preferably a resin-bonded laminated wood or a res-
in-bonded fibre composite material which contains lignosecellulosic fibres
from
annual plants.
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It has been shown that good results are achieved if the organically bonded
wood
material contains phenolic resin as a synthetic resin. In particular, the
organically
bonded wood-based material should contain synthetic resin in an amount of at
least 30% by weight, in particular at least 35% by weight, with the synthetic
resin
5 content preferably being 40% by weight.
In a preferred manner, the nails according to the invention consist of a
material
with a density > 0.65 g/cm3, in particular a density > 0.85 g/cm3 and
preferably a
density > 1.0 g/cm3, the density being in particular 1.3 g/cm3.
This means that deciduous woods can be used as a material for the nails ac-
cording to the invention. Hard woods include deciduous woods with densities
from 0.65 g/cm3, such as copper beech (Fagus sylvatica), hornbeam (Carpinus
betulus), maple (Acer pseudoplatanus or A. platanoides), preferably deciduous
woods with densities greater than 0.85 g/cm3, such as e.g. pernambuc (Caesal-
pinia echinata), bangkirai (Shorea ssp.) or some types of rosewood (Dalbergia
ssp, Machaerium ssp.), in particular preferably deciduous woods with densities
greater than 1.0 g/cm3, such as bongossi (Lophira alata) or lignum (Guaiacum
ssp.).
Suitable wooden materials that can be produced without the addition of binding
agents include compressed woods with densities greater than 0.65 g/cm3, in
particular with densities greater than 0.85 g/cm3 and preferably with
densities
greater than 1.0 g/cm3. These can be produced, for example, according to
W094/20273 A.
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Non-compressed veneer layer woods and plywoods made of types of wood with
sufficient density (see above) are suitable wooden materials that are produced
with the addition of binding agents. The commercially available veneer layer
woods with sufficient density include e.g. BauBuche made by Pollmeier Mas-
s sivholz GmbH & Co.KG, Creuzburg with a density of 0.68 g/cm3. Plywoods
with
veneer layers of equal thickness ¨ so-called multiplex boards ¨ made of beech
or birch with densities of 0.7 g/cm3, are offered by various manufacturers
such as e.g. UPM Plywood, Lahti, Finland. The preferred wooden materials with
portions of binding agent include compressed veneer layer woods, compressed
laminated wood and plywoods, e.g. made of beech veneer with average to high
compression with densities of 1.1 g/cm3 to 1.4 g/cm3, such as e.g. synthetic
resin compressed wood according to DIN 7707.
Structurally very similar to the wooden materials are compressed and glued
materials made of woody plant material, e.g. composed of monocotyledons that
include, among others, tissue from palm and bamboo growth. Compressed
bamboo products are known, for example, under the designation CoBAM (com-
pressed Bamboo). CoBAM has densities of 0.95 to 1.25 g/cm3.
Generally the nail shank can have any cross-section. For example, it can be
oval or polygonal. In a preferred manner, however, the nail shank has a
circular
diameter. Preferably the diameter of the nail shank or the smallest nail
thickness
is between 2 mm and 8 mm for an oval or polygonal nail, especially between 3.5
and 6 mm and preferably between 4 and 5 mm.
According to a further embodiment of the invention it is intended that the
nails
have a nail head in the form of a semi-lens-shaped dome which projects
radially
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outwards with respect to the shank axis. However, the nail shank is preferably
cut off at its end opposite the nail tip at an angle of 900 to the shank axis.
The nail length (head + shank + tip) usually varies between 20 mm and 90 mm,
in particular between 30 mm and 70 mm, preferably between 40 mm and 60
mm.
The nails according to the invention are preferably produced individually and
then magazined. They can be loaded into a nail setting tool either
individually or
in bulk via a storage container which feeds the nails to a nail setting tool -
ar-
ranged according to the one-sided alignment of the nail tips. Nails are
preferably
magazined in coils with punched tape into which the nails are inserted. During
insertion, the nails are pushed out of the punched tape without shearing off
the
fastener, in this case the punched tape. The structure of the perforated tape
re-
mains intact and is not shot into the components or distributed around the
work
area in the form of fragments, as is the case with sheared off fasteners. The
undamaged punched tape can either be disposed of as a whole or reused.
The nails according to the invention can be used to be nailed in by hand.
Alter-
.. natively, they can also be shot into a substrate using a nail setting tool,
for ex-
ample a pneumatic nailer.
With regard to further advantageous embodiments of the invention, reference is
made to the subclaims and the following description of an embodiment with ref-
erence to the enclosed drawing. In the drawing shows:
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Figure 1 the front end area of nails with different nail tips in front
view,
Figure 2a an embodiment of an inventive nail with a slit-shaped recess
pro-
vided at the head area,
Figure 2b the nail from Figure 2a with a wedge driven into the slot-
shaped
recess,
Figure 3 a possible cross-section of the nail shank of a nail according
to the
invention and
Figure 4 an alternative embodiment of a cross-section of the nail
shank.
Figures 2a and 2b schematically show a nail 1 according to this invention. The
is nail consists mainly of a lignocellulosic material. In the present case
it consists
of a synthetic resin-bonded laminated wood which contains 35 % by weight
phenolic resin as synthetic resin and thus has a density of more than 1 g/cm3,
specifically just under 1.3 g/cm3.
The nail 1 has a nail shank la, at the lower end of which a nail tip lb is
formed
with a circular cross-section, i.e. a conical round tip. The nail tip lb has
an axial
length which is approximately as large as the diameter of the nail shank la,
so
that the tip angle of the nail tip lb is 600
.
As shown in Figure ld, the tip angle can also be 90 , for example. It is
essential
that it is larger than 40 so that the splitting effect on nailed components
is
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smaller than with nails whose tip angle is smaller, for example at 200, as
shown
in Figure la.
The upper end region of the nail shank 1a is cut off perpendicular to the
longitu-
dinal axis of the nail. Thus the nail 1 has a head region 1c, which has the
same
cross-section as the nail shank la. As can be seen in the drawing, the head re-
gion 1c is further provided with a slot-shaped recess 2 which extends axially
from the upper end face of nail 1 over a length of several millimeters into
the
head region 1c or the nail shank la along a longitudinal central plane of the
nail
1 and penetrates the head region 1c or the nail shank la from one edge region
thereof to the opposite edge region thereof. A wedge 3 can be driven into the
recess 2 after or before the nail 1 is driven into a component or a substrate,
so
that the webs of material limiting the recess 2 are pressed apart and the head
region 1c widens as indicated in Figure 2b. The expansion increases the press-
ing forces between the head area 1c and the component into which the nail 1
with the head area 1c is/is driven, and as a result the pull-through
resistance of
nail 1 is increased.
The nail shank la and the head area 1c can have a smooth surface. However,
the circumferential surface of the nail 1 in the region of the nail shank la
and the
nail head 1c is ribbed in a preferred manner. In other words, the nail shank
1a or
nail head lc is provided with longitudinal grooves 4 which extend over the
entire
length of the nail shank 1a/ of the nail head 1c and are formed here in the
form
of notches with a triangular cross-section, so that wall sections with
trapezoidal
(see Figure 3) or triangular (see Figure 4) cross-section are formed.
