Note: Descriptions are shown in the official language in which they were submitted.
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A device for joining members
This invention relates to a device for joining two mem-
bers according to the preamble of claim 1, preferably for
joining two members to be glued together on their abutting
surfaces.
For example, if two wooden parts are glued at their
abutment they are generally joined with dowels, i.e. pin-
shaped wooden connecting pieces provided with longitudinal
grooves to increase the gluability. To keep the two wooden
parts firmly pressed together during hardening of the glue,
one uses clamps or similar devices.
However, in many cases it is not possible to use clamps,
for example when the two wooden parts do not enclose a right
angle or in certain assembly situations, e.g. when fastening
a wooden part to a wooden ceiling.
DE 86 lO 592 Ul discloses a device according to the pre-
amble of claim 1 for joining three boards disposed as a chan-
nel to form a hollow beam. The two parts of the device with
the barblike projections are joined together by a film hinge
and can thus, opened at right angles, be inserted with the
barblike projections into corresponding grooves in the cor-
ners of the hollow beam.
In the device of US-A 3,680,898 one joins two boards by
milling a broad, flat groove into one board and a narrow,
deep groove into the other board. One fastens in the deep
groove the barbed shaft of a hook-shaped element, and in the
broad groove a tongue onto which the hook-shaped element is
laterally slipped and then fixed with a wedge.
The problem of the invention is to provide a device for
joining members as with a dowel but without clamps or similar
devices.
This is obtained with the device characterized in claim
1. The subclaims state advantageous embodiments of the inven-
tion.
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The inventive device can in one embodiment have the form
of a dowel or pin. The pin is radially divided in the middle.
The members to be joined are each provided with a bore on the
surfaces with which they abut. The two portions of the pin
are then inserted into one and the other bore.
The pin has at both ends lateral barblike projections,
i.e. projections which lie laterally against the pin upon in-
troduction into the particular recess or bore but stand up
under tension, thereby preventing the pin from being drawn
out of the bores.
The barblike projections can for this purpose be formed
as flexible attachments on the periphery of the pin, for ex-
ample as rings or spirals extending around the pin. If the
pin is made of plastic the barblike projections can be formed
integrally with the particular pin part.
The two portions of the device are held apart against
the spring tension by a distance piece which is destroyed
when a heavy blow is applied in the axial direction to one of
the members and thus to the device, for example with a ham-
mer.
The distance piece can for this purpose consist of an
elongate element, for example a pin or strip, having a rated
breaking point. The distance piece can also be formed differ-
ently to be destroyed by a blow on one of the members to be
joined. It can e.g. consist of a body, in particular a hollow
body, such as a sheath or ball, made of a brittle material,
e.g. glass or ceramics such as clay.
However the distance piece can also be rendered ineffec-
tive by action from outside in a different way, e.g. by ac-
tion of heat, for example with a heater fan or a radiant
heater. For this purpose the distance piece can be formed as
a bimetallic element. The bimetallic element can be an elon-
gate element, e.g. a pin or strip, which holds apart the two
portions of the device and bends when heated in such a way
that the spring draws the two parts toward each other.
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When the device has been inserted with one and the other
portion into one and the other recess in the members to be
joined, the barblike projections lying down upon introduction
into the recesses stand up somewhat. This causes the two por-
tions of the device to move apart so~ewhat, for example one
millimeter, creating a corresponding gap between the members
to be joined.
To eliminate this gap, the two portions of the inventive
device are spring-loaded toward each other. The spring load-
ing can be provided for example by an elastic fastened with
one end to one portion of the device and with the other end
to the other. Instead of an elastic one can of course also
provide a flat spiral spring or the like to load the two por-
tions of the device toward each other.
When the two portions of the device have been introduced
into one and the other recess in the two members to be
joined, the distance piece is rendered ineffective by e.g.
hitting one of the two members to be joined from outside, for
example with a hammer, causing the distance piece to break.
The distance piece can for this purpose have a rated breaking
point or consist of a readily breakable, brittle material. If
a distance piece to be rendered ineffective by heat is pro-
vided, the area of the two members where the device is lo-
cated is heated e.g. with a fan heater or radiant heater.
The spring loading on the two portions of the device
moves them toward each other, thereby pressing together the
two members to be joined when the distance piece has been de-
stroyed or rendered ineffective. This eliminates the gap be-
tween the two members to be joined.
If the distance piece is formed as an elongate element
with a rated breaking point, the two portions of the elongate
element joined by the rated breaking point are preferably
fixed on the two portions of the device in such a way as to
be tensioned away from each other. This ensures that the two
portions of the element move apart after breakage of the
rated breaking point in such a way as not to obstruct the
CA 02226737 1998-01-13
drawing together of the two portions of the device by the
elastic or similar spring.
To ensure that the two portions of the device are joined
together firmly in the transverse direction, one provides an
axial guide, for example a sheath, into which the opposite
end portions of the two portions of the device are inserted.
The axial guide can also be formed differently, however, e.g.
by a pin on one portion of the device which engages a recess
in the other portion.
The inventive device is intended mainly for joiner's
work and for the woodworking industry, in particular in the
furniture area. However, it can also be used ~or joining two
members abutting with their flat surfaces made of different
materials, for example plastic, stone or metal members.
Along with pin-shaped dowels one mainly uses lamella
plates (nLamelloplattchen") for gluing wooden parts in a
joiner's workshop today. Using a machine with a milling cut-
ter, which is present in practically every joiner's workshop,
one mills in each of the two wooden parts to be joined a seg-
ment-shaped groove into which one inserts each half of the
ellipsoid lamella plate. In a second embodiment of the inven-
tion the two portions of the device are therefore designed as
small plates. Unlike a pin-shaped dowel, this provides the
possibility of correcting the position of the two wooden
parts in the longitudinal groove direction before the glue
hardens.
Two embodiments of the inventive device will be ex-
plained more closely below with reference to the drawing,
showing enlarged views as follows:
Fig. 1 shows a longitudinal section through a first em-
bodiment;
Fig. 2 shows a top view of a second embodiment; and
Fig. 3 shows a section along line III-III in Fig. 2.
According to Fig. 1 the device consists of a dowel com-
prising two portions 1, which are identically constructed in
the embodiment of Fig. 1 and therefore provided with the same
CA 02226737 1998-01-13
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reference signs. Portions 1 each have cylindrical shaft por-
tion 2 and head portion 3. Ring-shaped barblike projections 4
extend around each head portion 3.
The device is inserted with each portion 1 into bore 5,
6 in one and the other wooden part 7, 8 which are to be
joined together.
Barblike projections 4 are flexible and directed
obliquely rearward with respect to the particular introducing
direction (arrow 9). Under tension contrary to introducing
direction 9 they therefore stand up so as to prevent parts 1
from being drawn out of bores 5, 6.
However, one cannot avoid barblike projections 4 stand-
ing up somewhat when the device has been inserted into bores
5, 6. This moves portions 1 of the device out of bores 5, 6
somewhat, for example half a millimeter, thereby creating gap
10 between wooden parts 7, 8 to be joined.
To eli~inate gap 10 shaft portions 2 of parts 1 are axi-
ally movable in sheath 11, spaced distance a apart and loaded
toward each other by two elastics 12. Distance a is greater
than the width of gap 10, being for example 2 to 10 mm.
Elastics 12 are disposed laterally on shaft portions 2
in corresponding longitll~in~l recesses 13 in shaft portions 2
and fixed with their radially inward protruding ends 14 in
recesses 15 in shaft portions 2. They are likewise enclosed
by sheath 11.
Distance a is maintained by a distance piece formed by
strip-shaped element 16. Element 16 has rated breaking point
17 in the middle. It is formed as a flat S, the two ends of
the S being set obliquely in corresponding recesses 22, 23 in
the faces of one and the other shaft portion 2.
Portions 18, 19 of element 16 joined by rated breaking
point 17 are tensioned in opposite directions according to
arrows 20, 21 so that they move apart upon breakage of rated
breaking point 17. This enables elastics 12 to draw portions
1 of the device and thus wooden parts 7, 8 toward each other
in such a way that gap 10 disappears.
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In Fig. 1 each portion 1 has head portion 3 with a
greater diameter than shaft portion 2. However, portions 1
can also have the same diameter throughout. Also, head por-
tion 3 can have a smaller diameter than shaft portion 2. If
at least one of portions 1 is formed in this way, the device
is easier to assemble because sheath 11 can be pushed over
head portion 3 with projections 4 for example.
Instead of being provided with rated breaking point 17,
distance piece 16 can also be formed by a bimetallic element,
e.g. a bimetallic strip, between portions 1 which bends upon
a temperature change so that portions 1 of the device can be
drawn together by elastic 12 or similar spring. For changing
the temperature one can blow on the ~embers to be joined in
the area of the device, e.g. using a hair-dryer. In particu-
lar two bimetallic strips can also be fastened to one and the
other shaft 2 being supported on each other with their ends.
According to Figs. 2 and 3 the device for joining two
members not shown, in particular two wooden parts to be
glued, has two portions which are formed differently and
therefore provided with reference numbers 31 and 32.
Portions 31, 32 are formed as small plates each shaped
as a seqment of a circle with cut-off or rounded tips, the
chords of the two segments being located opposite each other.
Extending along the outside edge of each plate 31, 32 is
groove 33 in which ring 34 made of rubber or another elastic
material is disposed under tension. Ring 34 encompassing
plates 31, 32 causes them to be loaded toward each other.
The two long sides of each plate 31, 32 are provided
with rib-shaped projections 35 formed like barbs according to
Figure 3. Rib-shaped projections 35 extend parallel to the
chords of the segments forming plates 31, 32. Ribs 35 are
flexible and directed obliquely toward the other plate 31,
32.
Plates 31, 32 are inserted in the direction of double
arrow 36 into corresponding recesses in one and the other
wooden part not shown in Figs. 2 and 3, namely in correspond-
CA 02226737 1998-01-13
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ing segment-shaped grooves milled into the two wooden parts.
Barblike rib-shaped projections 35 fix plates 31, 32 in the
grooves, thereby joining them firmly with one and the other
wooden part.
Plates 31, 32 are loaded by elastic ring 34 toward each
other in the direction of arrow 36, i.e. perpendicular to the
parallel chords of the two segments forming plates 31, 32,
and guided movably.
In the initial position shown in Figs. 2 and 3, however,
plates 31, 32 are held apart at distance a by a distance
piece.
For this purpose plate 31 is provided with plate-shaped
projection or portion 37 joined integrally therewith and ex-
tending in the direction of arrow36 toward the other plate
32. Plate 32 has recess or notch 38. Between the corner area
of the two lateral edges 39, 40 of projection 37 and the cor-
ner area of the two lateral edges 41, 42 of notch 38 there is
in each case rated breaking point 43, 44 which is formed by a
thin ridge interconnecting plates 31, 32 integrally across
these corner areas.
Portion 37 and notch 38 are rectangular so that lateral
edges 39, 40 of portion 37 and lateral edges 41, 42 of notch
38 extend parallel to each other, namely in the moving direc-
tion of plates 31, 32 according to arrow 36.
When plates 31, 32 are disposed in one and the other
groove in the two joined members, one destroys rated breaking
point 43, 44 by hitting the outside of one of the two members
to be joined e.g. with a hammer, thereby breaking rated
breaking points 43, 44. Plates 31, 32 are then drawn toward
each other by distance a in the direction of arrow 36 through
elastic ring 44, and portion 37 thereby moved into notch 38.
This presses together the two members to be joined, thereby
eliminating a gap between said members.
When rated breaking points 43, 44 break, some material
can break off the ridge. To prevent plates 31, 32 from jam-
ming due to such material at edges 49, 41 and 40, 42 when be-
- CA 02226737 1998-01-13
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ing drawn together, edges 39, 40 of portion 37, except for
the corner area, are shifted inwardly somewhat from edges 41,
42 of notch 38 so as to form noses 39', 40', thereby forming
a gap between edges 39, 41 and 40, 42 for receiving this ma-
terial in the end position of the device in which plates 31,
32 are drawn together by elastic ring 34 and thus portion 37
has been moved into notch 38.
For guiding plates 31, 32 when they move toward each
other, and for fixing plates 31, 32 in their longitudinal and
transverse directions in the final state of the device, two
guide pins 45, 46 are provided on plate-shaped portion 37 of
plate 31 which extend in moving direction 36 from plate 31 to
plate 32 and engage bore 47, 48 in plate 2.
It should be noted that guide pins 45, 46 can likewise
be used for forming a rated breaking point to be destroyed by
a blow on one of ~he two members to be joined; these can be
the only rated breaking points of the device, or rated break-
ing points which are effective together with rated breaking
points 43, 44.
For this purpose each pin 45, 46 can be joined at its
end facing bore 47, 48 for example integrally with plate 32
at the opening of bore 47, 48.
Between guide pins 45, 46 plate-shaped portion 37 on
plate 31 has recess or notch 49 provided on its lateral edges
with locking teeth 50. Further, plate-shaped projection 51 is
provided in plate 32 in the middle of notch 38, being pro-
vided on each of its longitudinal edges 53 with locking tooth
5Z which engages like a barb between two locking teeth 52 on
the longitudinal edges of notch 49 in the end position of the
device, i.e. when portion 37 is moved into notch 38 and guide
pins 45, 46 moved into bores 47, 48.
While teeth 50 are of rigid design, teeth 52 on projec-
tion 51 are flexible so that they are bent away from plate 31
upon penetration of projection 51 into notch 49.
So that they cannot be bent toward plate 31 and thus
drawn out of notch 49 again in the engaged state between two
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teeth 50, teeth 52 are disposed in recesses 54 in longitudi-
nal edges 53 of projection 51, being shifted toward plate 31
in such a way that edge 55 of recess 54 facing plate 31 forms
a stop for tooth 52, preventing the latter from bending to-
ward plate 31.
Instead of one projection 51 shown in Figures 2 and 3,
each locking tooth 52 can also be provided on a separate pro-
jection which is bendable and spring-loaded toward teeth 50.
In this embodiment not shown, the teeth on the projections
are likewise of rigid design.
So that plates 31, 32 have lateral edges 57, 58 of sub-
stantially equal length, plate 31 is provided on both sides
with projection 59 extending obliquely outward and toward
plate 32, and plate 3Z is accordingly cut off obliquely at 60
in the area of its lateral edge 58.
Apart from elastic ring 34, the entire device consti-
tutes one injection-molded part, e.g. a plastic part for ex-
ample of polyamide, preferably reinforced with short fibers
such as glass fibers. Plates 31, 32 are thereby joined to-
gether integrally ~y rated breaking points 43, 44. Further,
guide pins 45, 46 are formed integrally on plate 31, projec-
tion 51 integrally on plate 32, and teeth 52 integrally on
projection 51.
In the final state the ~im~nsions of the device can cor-
respond to those of a lamella plate. For exampLe the device
can have a thickness of 2 to 8 mm, a length of 30 to 100 mm
and a width of 20 to 80 mm in the final state. Distance a can
be for example 3 to 10 mm.
