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Description  |
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FIELD OF THE INVENTION
This invention relates to a simple means for detachably connecting
structural members together. The connection is made by engaging a
resilient T-shaped tongue on a first member within a mating T-shaped slot
on a second member. Rotation of the tongue within the slot causes a
wedging action between the tongue and sloped inner surfaces of the slot
which stretches the tongue and compresses the portions of the tongue which
are in contact with the sloped inner surfaces of the slot. This draws the
tongue firmly into the slot. Once in place the tongue remains in tension,
holding the first and second members tightly together.
BACKGROUND OF THE INVENTION
There are many applications which require parts to be detachably connected
with a joint which is reliable, easy to operate, and holds the parts
firmly together. Some applications in which such joints are desirable are
in joining the components of a panel display system, in assembling modular
kitchen cabinets and in assembling shelving units. Of course, many other
applications are also possible.
For the purpose of illustration the novel joint of the invention is
hereinafter described in the context of a panel display system. Such
systems are frequently used for temporary displays in advertising,
displaying information at conferences and the like. Ideally, a panel
display system should be light in weight, inexpensive, quick and easy to
assemble and should allow a wide variety of configurations to be
constructed with a few basic components. A necessary prerequisite to
making a panel display system with these attributes is a means for
securely and easily detachably connecting the various components of the
system together. It can be readily appreciated that a good attachment
means for connecting the components of a panel display system will have
application in many fields where it is desirable to quickly and securely
detachably connect members together.
A typical panel display system includes a number of rigid members which can
be connected to form a structure. Typically the structure is in the form
of a framework with vertical members interlinked by a number of horizontal
members. Connectors, which are usually integral with the ends of the
horizontal members, are provided for joining the horizontal members to the
vertical members. After the framework of vertical and horizontal members
is erected, panels may be inserted in the rectangular spaces bordered by
the members.
The difficulty with currently available panel display systems is that they
use complicated means to connect the structural members. This makes these
systems either expensive or time consuming to assemble or both. Similar
problems exist in other fields in which detachable joints are used for
linking parts together.
Staeger, U.S. Pat. No. 4,583,359 shows a modern system for assembling a
display from portable frame members. The frame members are tubes with
longitudinal undercut grooves on their exterior surfaces. The end of one
tube can be clamped to a point along the length of a second tube by means
of a clamping element which is affixed to the end of the first tube. The
clamping element is inserted into one of the longitudinal grooves on the
second tube and tightened by turning a screw. Turning the screw forces
apart tie bar clamps at the end of the clamping element. As they are
forced apart, the tie bar clamps are drawn toward the body of the clamping
element. The tie bar clamps engage the undercut surfaces of the
longitudinal grooves in the second member and hold the first member
perpendicular to the second member.
The clamping mechanism described by Staeger has several parts and is
therefore, relatively expensive to make. Furthermore, when the Staeger
system is assembled, each joint must be individually tightened with a
screwdriver. This makes assembly of the system relatively time consuming.
Chenel, U.S. Pat. No. 4,778,487 describes a modular panel display system of
vertical and horizontal members which can be inter-connected to form a
frame work. The vertical members have longitudinal T-shaped slots and the
horizontal members have T-shaped bolts projecting from their ends. A
horizontal member may be attached to a vertical member by aligning the
bolt on an end of the horizontal member with the opening of the slot on
the vertical member, inserting the bolt into the slot, and twisting the
horizontal member about its axis. As the horizontal member is twisted the
ends of the bolt engage in the T-shaped slot. The bolt is locked into
place in the slot by a ball and spring detent mechanism. Chenel provides a
further mechanical locking mechanism to lock the horizontal member at one
of a number of particular positions along the vertical member. While the
Chenel panel display system appears to be quick to assemble, it is
relatively complicated and, therefore, expensive to manufacture.
SUMMARY OF THE INVENTION
This invention pertains to an interlocking joint in which a tongue
projecting from a first member is interlockably engaged within a groove in
a second member. The groove comprises: a narrow mouth extending through an
outer wall of the second member; a wide aperture extending through the
second member parallel to the mouth; and, sloped surfaces connecting the
inward edges of the mouth to the respective outward edges of the aperture.
The tongue comprises: a narrow segment extending from the first member;
and, a wide segment extending from the narrow segment.
In another aspect, this invention pertains to a member connectible with an
interlocking joint. The member comprises: an aperture in a surface of the
member; and, a resilient tongue with a first end affixed in the aperture
and a second end projecting from the aperture. The tongue comprises: a
narrow segment extending from the aperture past the surface; and, a wide
segment extending from the narrow segment.
In a third aspect, this invention pertains to a member connectable with an
interlocking joint. The member comprises a groove on a face of the member.
The groove comprises: a narrow mouth extending through an outer wall of
the member; a wide aperture extending through the member parallel to the
mouth; and, sloped surfaces connecting the inward edges of the mouth to
the respective outward edges of the aperture.
BRIEF DESCRIPTION OF THE DRAWINGS
In drawings which illustrate embodiments of the invention:
FIG. 1 is a perspective view of a framework of members in a display system;
FIG. 2 is a partially cut away perspective view of a horizontal member
connected to a vertical member;
FIG. 3 is a perspective view of a section of a vertical member similar to
the vertical member shown in FIG. 2 but having only one channel;
FIG. 4 is a perspective view of the end of a horizontal member similar to
the horizontal member shown in FIG. 2 but not having any channels;
FIG. 5 is a longitudinal section through the end of the member shown in
FIG. 4;
FIGS. 6(a), (b) and (c) are cut away views depicting the sequence of steps
in which a tongue is engaged in a slot;
FIG. 7 is a perspective view of an insert for receiving a tongue like the
tongue shown in FIGS. 4 and 5;
FIG. 8 is a perspective view of the insert shown in FIG. 7 cut away along
line A--A;
FIG. 9 is a perspective view of a member with a number of slots for
receiving tongues, like the tongues shown in FIGS. 4 and 5, at discrete
positions;
FIG. 10 is a perspective view of a shelf bracket for use in association
with the member shown in FIG. 9;
FIG. 11 is a perspective view of a unit for joining two slotted members at
right angles at a point away from the ends of the members;
FIG. 12 is a perspective view of a unit for joining parallel slotted
members at a point away from the ends of the members;
FIG. 13 is a partially cut away perspective view of th of an alternative
embodiment of a horizontal member; and
FIG. 14 (a), (b), (c), (d) and (e) show transverse sect through several
alternative configurations for members capable of lockable engagement with
tongues like those depicted in FIGS. 4 and 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows a temporary display stand comprising a framework of horizontal
members 10 and vertical members 12. Panels 20 are fitted into some of the
rectangular openings in the framework. Panels 20 are slightly wider than
the distance between vertical members 12 so that the edges of panels 20
fit inside slots 16 in vertical members 12. Panels 20 are thereby held
within the framework. Horizontal members 10 may also have longitudinal
slots 22 to receive the upper and lower edges of panels 20 so that panels
20 are firmly retained in, and stabilize the framework.
FIG. 2 shows the connection of one horizontal member 11 to one vertical
member 13 in accordance with the present invention. Horizontal member 11
has a projecting tongue 14 which is lockably engaged with a longitudinal
slot 16 provided in face 18 of vertical member 13. The upper portion of
vertical member 13 has been cut away to better show the engagement of
tongue 14 in slot 16. Horizontal member 11 is held firmly in place at
right angles to vertical member 13 by frictional engagement between the
end 20 of horizontal member 11 and the face 18 of vertical member 13 and
between tongue 14 and the inside surfaces of slot 16.
FIG. 3 is a detailed perspective view of a section of a slotted member 30
according to the invention. Member 30 may be made of wood, plastic,
lightweight metal or any other material which combines the desirable
qualities of light weight, durability, attractive looks and reasonable
cost.
Member 30 has a face 32 and a slot 34 extending longitudinally along face
32. The sides of slot 34 are undercut to form ridges 36 on either side of
slot 34 which define a narrower mouth 38 and a wider inner area 40. Mouth
38 has a width D.sub.1. Inner area 40 has width D.sub.2. Face 32, which
forms the outside surface of ridges 36, is planar so that no unattractive
gaps are left when the flat end of another member is butted against face
32. Sloped surfaces 42 are formed on the inside of ridges 36. Sloped
surfaces 42 are inclined toward mouth 38 at an angle between about
4.degree. and 15.degree..
The preferred angle of inclination of sloped surfaces 42 towards mouth 38
depends upon the material from which slotted member 30 and the tongue
which is to be engaged in slot 34 are made. If the tongue is made of nylon
then the preferred angular ranges are between about: 4.degree. and
6.degree. if member 30 is made of wood; 6.degree. and 10.degree. if member
30 is made of plastic; and 10.degree. and 14.degree. if member 30 is made
of metal. Where member 30 is made of wood and the tongue to be engaged in
slot 34 is made of a material harder than wood, surfaces 42 may become
scored by the action of engaging the tongue in slot 34 if the angle of
inclination of sloped surfaces 42 toward mouth 38 exceeds about 6.degree..
When sloped surfaces 42 are inclined toward mouth 38 at an angle of less
than about 4.degree. and when a tongue is engaged in slot 34 (as described
with reference to FIG. 6 below) the tongue may not be drawn into slot 34
far enough to make the joint tight. Consequently, the joint may be looser
than it would be if sloped surfaces 42 were inclined at a higher angle
toward mouth 38. Where sloped surfaces 42 are inclined toward mouth 38 at
an angle greater than about 15.degree. and when a tongue is engaged in
slot 34 (as described with reference to FIG. 6 below) the tongue may be
subjected to so much force as it is drawn into slot 34 that the tongue may
break.
With the sloped surfaces, 42, on their inner surfaces, ridges 36 taper from
a thicker area in their portions away from mouth 38, to a thinner area in
their portions adjacent to mouth 38.
FIG. 4 shows a member 50 capable of lockable engagement with the slotted
member shown in FIG. 3 by means of a tongue 52 which is designed to engage
within slot 34. Tongue 52 projects from the end surface 54 of member 50.
The thickness of tongue 52 which is represented by the dimension T is less
than D.sub.1, the width of mouth 38, so that tongue 52 can be inserted
into slot 34. Tongue 52 comprises a narrow cylindrical segment 56
extending from member 50 having a diameter, W.sub.1, which is less than
the width D.sub.1 of mouth 38; and, wide segment 58 having a width
W.sub.2, which is greater than the width D.sub.1 of mouth 38. Wide segment
58 extends from narrow segment 56. Narrow segment 56 and wide segment 58
both have the same thickness T. Width W.sub.2 is less than the width
D.sub.2 of inner area 40 of slot 34. The narrow segment 56 of tongue 52 is
separated from wide segment 58 of tongue 52 by shoulders 60.
Shoulders 60 extend generally perpendicularly to narrow segment 56. The
front and rear edges 61 of shoulders 60 are bevelled at an angle of
approximately 45.degree. to the faces of shoulders 60.
FIG. 5 shows a longitudinal cross section through the end of member 50.
Tongue 52 is an extension of body 59 which lies within aperture 66
provided in end 54 of member 50.
Body 59 is retained in aperture 66 by transversely extending pins 68 which
snap into cross-drilled apertures 70 when body 59 is slidably inserted
through aperture 66. Body 59 may be removed by pushing pins 68 inwardly
(i.e. toward one another) with suitable tools inserted through apertures
70. Body 59 may require replacement if it is broken or worn or for any
other reason. If this happens, body 59 can be easily replaced by removing
the old body 59 as described above, squeezing the pins 68 on a replacement
body 59 together, placing the end of replacement body 59 into aperture 66
and pushing replacement body 59 into aperture 66 until pins 68 snap into
cross-drilled apertures 70.
Body 59 has a flat upper surface 72 which, in its equilibrium position,
lies below end surface 54 of member 50. Body 59, is preferably made from a
single piece of a durable resilient material such as nylon. Suitable
resilient properties are obtained where body 59 is made of a general
purpose type 6 nylon available under the trademark ULTRAMID B306 NYLON 6
POLYMER which may be obtained from BASF Canada Inc. Body 59 preferably
measures approximately 26 millimeters from pins 68 to upper surface 72.
Narrow segment 56 is 6.5 millimeters in diameter
FIG. 6(a) shows a cross-section of tongue 52 inserted in but not engaged
with slot 34. Wide segment 58 of tongue 52 projects into the wider inner
area 40 of slot 34. The end surface 54 of member 50 is in contact with
face 32 of member 30 on both sides of mouth 38. Shoulders 60 of tongue 52
lie inside slot 34. The tops of the bevelled edges 61 of shoulders 60
extend past outer edges 62 of sloped surfaces 42. Tongue 52 is engaged in
slot 34 by rotating member 50 90.degree. about its longitudinal axis.
Tongue 52 rotates along with member 50. As this happens, bevelled edges 61
of shoulders 60 come into contact with the inner edges 62 of mouth 38.
Continued rotation of tongue 52 causes bevelled edges 62 to ride up onto
the inside of ridges 36 bringing portions of shoulders 60 into contact
with sloped surfaces 42.
FIG. 6(b) shows tongue 52 partially engaged in slot 34. As depicted in FIG.
6(b), member 50 has been rotated by approximately 35.degree. in comparison
to the position shown in FIG. 6(a). Shoulders 60 on tongue 52 are in
contact with sloped surfaces 42 inside slot 34, and have ridden up sloped
surfaces 42 inside slot 34.
Pins 68 prevent body 59 from rotating relative to member 50 as tongue 52 is
twisted into place in slot 34. Pins 68 also retain the lower end of body
59 in aperture 66 as shoulders 60 ride up on surfaces 42. Other ways of
retaining body 59 in aperture 66 such as gluing body 59 in place or
moulding body 59 as an integral part of member 50 may also be used and
come within the scope of the invention.
The resilient construction of body 59 allows it to bear a tension load as
continued rotation of body 59 causes shoulders 60 to ride further up
surfaces 42 by means of a wedging action between shoulders 60 and surfaces
42. The force exerted by surfaces 42 on shoulders 60 also causes
compression of the portions of wide segment 58 underlying shoulders 60
and, if surfaces 42 are resilient, causes compression of the portions of
surfaces 42 in contact with shoulders 60. In FIG. 6(b), the force exerted
on shoulders 60 by sloped surfaces 42 has caused body 59 to move up toward
slot 34, thus taking up any slack between pins 68 and holes 70 and between
member 50 and member 30. Continued rotation of tongue 52 relative to slot
34, has caused shoulders 60 to be drawn further into slot 34. This has
placed body 59 in tension between pins 58 and shoulders 60 and has caused
compressive forces between surfaces 42 and shoulders 60. The combined
effect of the tension stretching of body 59 and the motion of body 59 as
slack is taken up between the various parts of the joint has drawn upper
surface 72 upwardly away from its equilibrium position and toward face 32
of member 30.
While body 59 is preferably resilient so that it can stretch as shoulders
60 ride up sloped surfaces 42, it can readily be seen that a construction
in which tongue 52 is inextensible and rigidly attached to member 50 would
work in a similar way and would come within the scope of the present
invention if a resilient pad were included between end surface 54 of
member 50 and face 32 of member 30; or, between shoulders 60 and sloped
surfaces 42.
FIG. 6(c) shows tongue 52 fully engaged in slot 34. Member 50 has been
rotated about its axis by 90.degree.. Wide segment 58 of tongue 52 has
been pulled completely into slot 34 by the wedging action of shoulders 60
riding up sloped surfaces 42. Body 59 has been stretched further to the
point that upper surface 72 is in contact with (i.e. butted against) face
32 of member 30. The tension in body 59 between pins 68 and shoulders 60
holds member 50 against member 30. Member 50 is held in place with respect
to member 30 by frictional forces between the end surface 54 of member 50
and face 32 of member 30, between the shoulders 60 and the sloped surfaces
42 and between upper surface 72 and face 32 of member 30. Ridges 36 are
pinched between shoulders 60 and upper surface 72.
The foregoing discussion explains the basic inventive concept of the
present invention. The following discussion describes a variety of parts
which embody this inventive concept.
It may be necessary to anchor one end of a member to a point on a surface
where, for some reason, it is difficult or undesirable to cut a slot. FIG.
7 shows an insert 75 capable of lockable engagement with tongue 52. Insert
75, which is preferably made of metal but may also be made of strong
plastic or another suitable material, may be installed in a hole of the
same diameter as insert 75 drilled at the desired position on the surface
without any need for providing a full length slot on the surface. The
exterior of insert 75 is provided with sharp points 76. Insert 75 is
installed by forcing it into the hole drilled in the surface. As the
insert is pushed into the hole, points 76 cut longitudinal grooves in the
wall of the hole. After insert 75 is fully inserted into the hole, the
installation is completed by rotating insert 75 through approximately
45.degree.. During this rotation, points 76 cut circumferential grooves in
the walls of the hole. Insert 75 is secured in the hole by the points 76
which sit within the circumferential grooves. Points 76 have a profile
which resists extraction of insert 75 from the hole. Insert 75 has a mouth
74 in its upper surface which is sized and shaped to accept tongue 52 in
the same manner described above in relation to FIGS. 6(a), (b) and (c).
FIG. 8 is a section taken along line A--A of insert 75 shown in FIG. 7. The
internal profile of insert 75 is similar to the internal profile of slot
34 shown in FIG. 3. Sloped surfaces 78 lie on either side of mouth 74 and
are inclined toward mouth 74. Tongue 52 may be engaged within insert 75 in
a manner analogous to the engagement of tongue 52 in slot 34 as described
above with reference to FIGS. 6 (a), (b) and (c).
FIG. 9 shows a unit 81, which is designed to support shelf bracket 91 which
is shown in FIG. 10. Unit 81 has a surface 82 having a series of discrete
slots 84. Each slot is capable of receiving a tongue 92. The rear surface
83 of unit 81 adjacent to slots 84 is shaped to provide sloped surfaces 85
on either side of each of slots 84. Tongue 92 engages in one of slots 84
in the same manner described above in relation to FIGS. 6(a), (b) and (c).
Unit 81 can be attached to a member (not shown) by means of tabs 86, which
snap into a correspondingly profiled groove in the member.
FIG. 10 shows a shelf bracket 91 which is designed to attach to unit 81
shown in FIG. 9. A tongue 92 and a pin 94 protrude from the base 90 of
bracket 91. Tongue 92 and pin 94 are spaced apart a distance equal to the
distance between adjacent slots on unit 81. Base 90 is flexible to allow
pin 94 to be pulled away from surface 82 while tongue 92 is rotated into
engagement in one of slots 84. When tongue 92 is engaged in a slot 84, pin
94 is aligned with the adjacent slot 84. Base 90 is then released,
allowing it to flex toward surface 82 to hold pin 94 in the adjacent slot.
This prevents mounting bracket 91 from rotating relative to unit 81,
thereby locking mounting bracket 91 in place. The side of base 90 away
from tongue 92 is equipped with a shelf mounting means such as peg 98 for
supporting a shelving unit. Peg 98 may be replaced with a hook or other
fixture as desired.
FIG. 11 is a perspective view of a unit 100 for joining two slotted members
at right angles at points away from their ends. The ability to join
members in this manner allows for more flexibility in the design of
frameworks of members using the present invention. Unit 100 comprises a
rectangular base 101 having tongues 102, 104 on opposite faces. The wide
segment 106 of tongue 102 is aligned transversely on base 101 for
engagement in the slot of a first member (not shown) extending parallel to
the long axis of base 101. Wide segment 108 of second tongue 104 is
aligned with the long axis of the base, perpendicular to wide segment 106
of tongue 102, for engagement in the slot of a second member (not shown)
perpendicular to the first member. A pin, 110 is provided to prevent base
101 from rotating with respect to the first member. Unit 100 is installed
by inserting first tongue 102 in a slot 34 in a first member and flexing
base 101 to allow pin 110 to clear the first member while first tongue 102
is rotated 90.degree. into engagement within slot 34. Base 101 is then
released to allow pin 110 to fall into slot 34. Second tongue 104 is then
inserted into slot 34 in the second member and the second member is
rotated 90.degree. with respect to the first member to engage second
tongue 104 within slot 34 in the second member.
If, it is awkward or impossible to install unit 100 as described above
because the second member cannot be rotated relative to the first member,
or because it is impractical to rotate the second member relative to the
first member, then unit 100 may be installed while the first and second
members are maintained perpendicular to each other. This is done by
inserting tongue 102 into slot 34 in the first member, inserting tongue
104 into slot 34 on the second member, and rotati | | |
