U.S. patent number 3,719,389 [Application Number 05/144,915] was granted by the patent office on 1973-03-06 for thermo plastic tubing furniture.
Invention is credited to Douglas G. Burton, Norman L. Kiger.
United States Patent |
3,719,389 |
Burton , et al. |
March 6, 1973 |
THERMO PLASTIC TUBING FURNITURE
Abstract
A method and apparatus for furniture construction entails the
forming of thermo-plastic tubing side and cross frame sections
wherein joints for securing interconnected members to each other
comprise flattened closed loop clamping sections integrally
connected with adjoining frame member portions. The loop sections,
even in unstressed condition of the frame members, are dimensioned
to be just equal to, or slightly smaller than the tubular members
that are retained and clamped therein. Further, the construction is
such, that upon assembly the portions of the tubular members on
either side of the several flattened closed loop clamping sections
are stressed to hold these portions closer to each other, so that
they will more tightly grasp the tubular members that each
encircles.
Inventors: |
Burton; Douglas G. (Whittier,
CA), Kiger; Norman L. (Garden Grove, CA) |
Family
ID: |
22510726 |
Appl.
No.: |
05/144,915 |
Filed: |
May 19, 1971 |
Current U.S.
Class: |
297/440.24;
D6/375; 297/DIG.1; 403/231; 403/347; 403/383; 297/447.4;
297/451.11; 297/451.13 |
Current CPC
Class: |
A47C
3/00 (20130101); A47C 5/12 (20130101); Y10T
403/7003 (20150115); Y10S 297/01 (20130101); Y10T
403/7098 (20150115); Y10T 403/4602 (20150115) |
Current International
Class: |
A47C
5/00 (20060101); A47C 5/12 (20060101); A47C
3/00 (20060101); A47c 004/02 (); A47c 007/00 () |
Field of
Search: |
;297/440-452,456,DIG.1,DIG.2 ;46/15-17,29,31
;52/646,648,650,653,654,684 ;29/453 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Nunberg; Casmir A.
Claims
We claim:
1. Furniture construction comprising
a plurality of tubular frame members, and
joint means for a securely interconnecting at least some of said
tubular members to each other, said joint means comprising
resilient clamping means formed integrally with one of said members
for substantially and tightly encircling a second of said members
in a stressed clamping relation,
said clamping means comprising an integral portion of said one
tubular member that is flattened and formed into a substantially
closed configuration closely conforming to the exterior cross
sectional configuration of said second member that is clamped
therein,
said clamping means having interior dimensions substantially equal
to, but not greater than, comparable dimensions of said second
member clamped therein,
whereby the portions of said first tubular member on opposite sides
of said clamping means may be spread apart to resiliently deform
said integral clamping flattened clamping portion to allow
insertion of said second member therein, and whereby the resilience
of said clamping means will urge said flattened clamping portion
into a tight clamping encirclement of the second member clamped
therein, and
means for urging said portions of said one member on opposite sides
of said clamping means toward each other and retaining them in a
stressed condition under such urging to thereby enhance the
gripping action caused by the inherent resilience of said flattened
clamping portion.
2. The furniture construction of claim 1 wherein said last
mentioned means comprises other elements of said furniture
construction that interconnect said portions on either side of said
flattened clamping means, whereby when said furniture construction
is assembled at least some of the members thereof are stressed by
other members into secure clamping relation.
3. The construction of claim 2 wherein said first member comprises
a side frame having a substantially vertical rear leg section, a
substantially vertical forward leg section considerably shorter
than said rear leg section and an arm section integrally
interconnecting the upper portion of said rear leg section with the
upper portion of said forward leg section,
said clamping means being formed as an integral portion of the
connection between said arm section and the upper end of one of
said leg sections, said clamping means comprising a flattened
substantially closed loop formed at said intersection of said arm
section and said one leg section and opening inwardly of said side
frame,
said second member comprising a substantially horizontal cross
member received and resiliently clamped within said flattened
closed loop portion,
said means for urging said portions of said one member on opposite
sides of said clamping means toward each other comprising a second
substantially horizontal cross member connected to and between said
rear and forward leg sections and having a length less than the
distance between said leg sections when said side frame is in
unstressed condition, whereby when said second horizontal cross
member is connected to and between said forward and rear leg
sections the side frame is stressed to retain the leg sections in a
position that tends to close the flattened loop of said clamping
means and thereby retain it in gripping engagement with said second
member therein.
4. The construction of claim 3 including
a second side frame substantially identical to said first mentioned
side frame and having substantially vertical rear and forward leg
sections integrally interconnected by a second arm section,
said second side frame being formed with clamping means comprising
a flattened integral closed loop positioned at the intersection
between said second arm section and one of said second leg
sections,
said first mentioned cross member also being received and securely
gripped within said flattened closed loop of said second side
frame,
a third substantially horizontal cross member interconnecting leg
sections of said second side frame and having a length less than
the distance between said leg sections of said second side frame
when the latter is in unstressed condition to thereby urge and
retain said second leg sections to and in a position wherein they
exert an increased clamping and gripping action upon said first
cross member, and means for retaining said side frames in mutually
spaced relation.
5. The apparatus of claim 1 wherein said one member comprises first
and second mutually angulated cross members, each integrally
connected at a corner thereof by means of an integral flattened
substantially closed loop, said integral flattened loop comprising
said clamping means, and wherein said second member comprises an
upstanding frame member securely retained and clamped within said
flattened closed loop.
6. The apparatus of claim 1 wherein said one member comprises a
first substantially U-shaped rectangular frame half section having
forward and rear cross members and a bight member extending
therebetween, said clamping means comprising a first and second
flattened substantially closed loop clamping sections integrally
connecting said bight portion with said forward and rear cross
members respectively, wherein said second member comprises a side
frame having substantially upstanding forward and rear leg sections
integrally interconnected by arm section, said forward and rear leg
sections respectively extending through and clamped within
respective ones of said flattened closed loop sections of said
U-shaped frame half section, and wherein said means for retaining
portions of said one member on opposite sides of said clamping
means in a stressed condition and urging them toward each other to
tend to close said flattened loop comprises a second substantially
U-shaped rectangular frame half section having forward and rearward
cross members and a bight member extending therebetween, said
second frame half section having flattened substantially closed
loop clamping sections integrally interconnecting its bight section
with said forward cross member and with said rear cross member, and
means for fixedly connecting rear and forward cross members of said
first frame half section to respective rear and forward sections of
said second frame half section, and including
a second side frame comprising second forward and second rear leg
sections integrally interconnected by a second arm section,
said second forward and rear leg sections respectively extending
through and clamped within said respective ones of said flattened
closed loop sections of said second frame half section,
each of said side frames being formed with a flattened
substantially closed loop clamping section integrally connecting
the arm section thereof with the rear leg section thereof so that
each rear leg section is spaced from each forward leg section, when
the side frame is in unstressed condition and not assembled in the
furniture construction, by a distance greater than the distance
between the two flattened closed loop clamping sections of the
associated frame half section, and
an upper cross member extending through and clamped within said
flattened closed loop clamping section of said first and second
side frames, whereby assembly of said construction will stress all
of said integral flattened closed loop clamping sections by holding
the associated member sections on opposite sides thereof in closer
relative position to each other, to thereby enhance the encircling
and gripping action of the respective flattened closed loop
clamping sections upon the respective member sections received
therein.
7. The apparatus of claim 6 including a plurality of seat forming
slats extending between said upper cross member and the forward
cross members of said first and second frame half sections, each
slat comprising an integral flattened tubular member having the
ends thereof bent to form a resilient tubular member grasping loop
that is resiliently enlarged to partly encircle and grip the
respective upper cross member and forward cross member.
8. The apparatus of claim 7 including a third and fourth
substantially U-shaped frame half sections each having forward and
rear cross members and a bight section integrally joined to
respective ones of the associated forward and rear cross members by
clamping means formed by flattened closed loop integral sections
thereof, the respective clamping means of said third and fourth
frame half sections receiving and clamping respectively different
ones of said side frame legs, and
means for fixedly interconnecting said third and fourth frame half
sections.
9. The apparatus of claim 8 wherein said tubular members are of
generally circular cross section and wherein said flattened closed
loop sections have substantially mating circular configuration.
10. The apparatus of claim 8 wherein at least some of said tubular
members have substantially polygonal cross sections, and said
flattened closed loop sections form polygonal loops of mating
configuration.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods and apparatus for
construction of furniture, and more particularly concerns tubular
furniture involving improved joint arrangements and
configuration.
2. Description of Prior Art
Furniture construction is among the oldest of tasks to which man
has devoted inventive ingenuity. With the fast spreading outdoor
living style in areas of mild climate there is a rapidly developing
requirement for sturdy lightweight and attractive furniture having
the ability to withstand relatively rough handling and abuse of
outdoor use, and, of primary importance, the ability to endure
under adverse weather conditions.
Presently available outdoor furniture includes pieces having frames
of wood, steel or aluminum. Commonly, springs supports and cushions
or plastic strips of webbing are employed for body support. Among
the many different types of outdoor furniture, those shown in U.S.
Pat. No. 2,993,733 to Pinkham, U.S. Pat No. 3,230,013 to Morrison
et al, U.S. Pat. 3,180,682 to Paulen and U.S. Pat. 2,731,078 to
Cadman et al. are made of plastic. Such furniture may be well
withstand adverse weather. Nevertheless, the prior art
constructions are difficult and expensive to fabricate, requiring
complex and costly molding and fabricating operation. Yet they fail
to take advantage of tubular construction that provides maximum
strength with minimum weight and cost. Where tubular frames are
employed, these are generally of metal, and conventional joints
such as screw, nut and bolt or welding arrangements are used, as
shown in the patent to Morrison U.S. Pat. No. 3,471,200 for
example. The welded joint is exceedingly expensive and difficult to
fabricate whereas the bolted joint involves relatively complex
assembly and nevertheless, fails to withstand either weather or
hard use.
Accordingly, it is an object of the present invention to provide
strong, lightweight and inexpensive yet attractive furniture
construction and methods that eliminate most of the above
identified disadvantages through the use of a novel tubular
construction and joint.
SUMMARY OF THE INVENTION
In carrying out principles of the present invention in accordance
with a preferred embodiment thereof, tubular furniture construction
is accomplished by forming first and second frame members of
mutually angulated configuration and interconnected by a flattened
substantially closed loop clamping section that integrally joins
the two frame members. Another frame member is retained and clamped
within the flattened closed loop clamping section of which the
clamping action is enhanced by still other portions of the
furniture construction that stress the first and second frame
members toward each other and maintain these in such stress
conditions to urge the flattened closed loop to still further
closed condition, thus more tightly to grasp the frame member
clamped thereby. In one embodiment a pair of substantially
rectangular cross member frame half sections each is formed with
one of the above described flattened closed loop clamping sections
at each corner. Each clamping section receives and clampingly
secures a respective one of the four legs of the furniture
construction. In some arrangements the legs are formed as part of a
pair of side frames that are, in part, joined to each other by an
upper cross member secured at its respective ends to said frames by
means of flattened substantially closed loop clamping sections
integrally connecting adjoining mutually angulated sections of the
respective side frames.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a pictorial illustration of a chair constructed in
accordance with the present invention, with most of the body
support slats not shown, or shown partly broken away;
FIG. 2 is a view of one of the side frames showing an unstressed
sprung condition of the legs in dotted lines, and also showing in
phantom lines the position of the substantially horizontal cross
frames;
FIG. 3 is a detailed view of one of the clamping joint closed loop
sections of the chair of FIG. 1;
FIG. 4 is a view, with parts broken away, of one of the assembled
cross frame full sections;
FIG. 5 is an exploded view, showing in detail connection of two
frame half sections, and
FIGS. 6, 7, 8 and 9 show different arrangements of flattened closed
loop clamping sections adapted for use with tubular members of
different cross sectional configurations.
DETAILED DESCRIPTION
As illustrated in FIG. 1, a chair constructed in accordance with
principles of the present invention, is formed of first and second
substantially upright side frames, each composed of a substantially
vertical rear leg section 10, 12 and a substantially upright
forward leg section 14, 16, interconnected by curving arm sections
18, 20 that extend rearwardly and generally upwardly in the
indicated curved condition to provide arm rests. An upper cross
member 22 extends between and is rigidly connected to the
respective side frames. First and second substantially rectangular
cross member frame full sections 24, 26 are fixedly connected at
the respective corners thereof to the several side frame legs. The
uppermost of the two rectangular cross member frame sections is
positioned substantially near the upper end of the forward legs 14
and 16 and is connected to the rear legs 10, 12 at a point
intermediate their ends. The lower of the two cross member frame
sections is connected to the several chair legs at the bottom ends
thereof. The vertical position of sections 24, 26 relative to the
legs may be varied as deemed necessary or desirable for appearance,
use and assembly, as long as requisite rigidity of the structure is
retained.
Body support in the illustrated chair is formed by a plurality of
slats, of which only two are shown at 28 and 30, with slat 30 being
broken away for clarity of the illustration.
Preferably, all of the parts of the chair illustrated in FIG. 1,
are formed of a suitable plastic tubing having the desired
qualities of weather resistance, rigidity, resilience and thermal
forming to enhance and facilitate the shaping and assembly
operations to be described in detail hereinafter. Among the many
known plastic materials that are suitable for use in connection
with the present invention, are those known as PVC
(polyvinylchloride plastic or resin), ABS
(acrylonitrile-butadiene-styrene plastic), high impact PS
(polystyrene plastic), PP (polypropylene plastic or resin) and
various other plastics including buterates, acrylics, cellulosics
and acetals. In particular, the wide availability of such heat
formable, rigid and resilient plastics in tubular form provides a
ready source of inexpensive material for practice of the present
invention. As an example, but without limitation, the commonly
available polyvinyl chloride extruded as vacuum formed tubing of
1.35 inches outside diameter, and having a wall thickness of 0.133
inches, is conveniently applicable for practice of this
invention.
Although other types of tubing, and even metallic tubing, may be
employed in the practice of this invention, the ease of forming
thermoplastic tubing particularly adapts this type of material to
the methods of construction and assembly and, in particular, to the
structural joint formation that comprise significant aspects of the
present invention.
As seen in FIGS. 1 and 2 the upper cross member 22 is fixedly
secured at its respective ends to the two side frames by means of
resilient clamping joints 32, 34 respectively. Each of these
clamping joints comprises a flattened section 33, 35 forming a
substantially closed loop that integrally connects the adjoining
portions (such as leg 10 and arm 18) of the side frame on opposite
sides of the loop. Each side frame is formed of a straight section
of tubing of roughly proper length, that is heated until it is
workably soft, and then bent upon a form to assume the shape
generally illustrated in dotted lines in FIG. 2. Clamping section
33 is flattened and formed by clamping action applied at neck
portions 36, 38, while a mandrel is positioned temporarily within
the loop that is being formed.
When so formed to provide the side frame shown in FIG. 2, having
rear and forward legs 10 and 14 interconnected by the arm section
18 and including the integral flattened closed loop portion 33, the
leg 10 will assume the rearwardly sprung position illustrated in
dotted lines in FIG. 2. In this unstressed position, and before any
cross member, such as member 22, has been clamped within the loop
33, the two mutually opposed neck portions 36, 38 are in, or nearly
in, mutual abutment with each other. The two adjoining tubular
sections 10 and 18 on either side of the flattened loop are then
temporarily expanded, resiliently and elastically, to facilitate
insertion of the cross member 22. The natural resilience of the
side frame then causes flattened loop section 33 to resiliently
grasp the encircled cross member 22, but the loop cannot fully
close around the cross member. It will remain with the neck
portions 36, 38 somewhat spaced from each other.
When assembled as described below, the side frame of FIG. 2 will
assume a position wherein rear leg 10 is as shown in solid lines,
such position being retained by connection with the horizontal
cross frames 24, 26. Thus, when assembled, the two legs, the
forward leg 14 and the rear leg 10, of each side frame are
positioned closer to each other than when in unassembled and
unstressed condition, whereby further clamping action is exerted by
the flattened loop 33 upon the encircled cross member 22 which is
firmly locked in place.
Each cross frame 24, 26 is identical to the other and for this
reason only one need be described. As shown in detail in FIGS. 3, 4
and 5, the cross frame full section is formed of two substantially
identical U-shaped frame half sections that are fixedly
interconnected. One of these frame half sections includes a forward
cross frame half member 39 and a rear half frame cross member 41,
interconnected by a bight portion 40. These sections are also made
and formed of the above described heat formable, rigid, resilient
plastic tubing of circular cross section. Each of these frame half
sections is provided at its respective corners with a flattened
substantially closed loop clamping section 42, 44 similar to
flattened clamping sections 32, 34 of the two side frames. However,
for the cross frames the adjacent tubular portions on opposite
sides of the flattened clamping section extend substantially at
right angles with respect to each other, rather than at the
relatively acute angle of the similar side frame portions.
Flattened closed loop clamping sections 42, 44 terminate in neck
portions 43, 45 and 47, 48 which are in, or substantially in,
abutment with each other when the two frame half sections are
connected, but before the tubular members clamped thereby are
inserted. This relation is shown in FIG. 4. When the tubular
members (legs 12 and 16) are inserted (in the manner to be
described below) the sides of the respective flattened clamping
sections 42, 44 are resiliently and elastically expanded (as shown
in FIG. 3) so that the two neck portions are mutually spaced in a
manner analagous to that described in connection with the flattened
clamping sections 33, 35 of the side frame.
A second U-shaped cross frame half section (identical to the first,
) comprises forward and rear half cross members 53, 54 and a bight
member 50. A pair of substantially closed loop clamping sections
(of which only that indicated at 51 is shown) integrally connect
the bight member 50 with the respective half cross members 53 and
54. Each of the U-shaped frame half sections is individually heated
and formed to provide the overall U-shaped configuration
illustrated. The flattened clamping sections are also formed when
heated. These are formed, just as described in connection with the
formation of clamping sections 32, 34, by stretching and deforming
the tubular section to flatten it and bend it about a removable
mandrel to the desired closed loop configuration.
In forming the flattened substantially closed loop clamping
sections, a pair of mandrels are inserted into the heated tubular
portions adjacent opposite sides of the member to be flattened and
looped, with the adjacent ends of the mandrels mutually spaced from
each other within and along the length of the tubular member to be
formed by substantially the peripheral distance of the loop that is
to be formed in the tubing. With the mandrels inserted, the section
of the tubing between the mandrels is flattened and clamped over
and around a third mandrel, of which the exterior defines the
interior shape of the flattened clamping loop. After withdrawal of
the mandrels that are inserted for the formation of the flattened
clamping loop, further forming of the particular side frame or
U-shaped frame half sections is accomplished as necessary. The part
is then allowed to cool, removed from the form and the ends are
trimmed to the desired length.
When completely formed, but not connected to each other, the two
U-shaped frame half sections have the respective legs or half cross
members 39, 41, 53, 54 thereof extending from the bight sections at
an angle somewhat greater than the illustrated 90.degree., whereby
these legs are outwardly sprung. To connect the two frame half
sections and form a single substantially rigid cross frame full
section, these resilient and outwardly sprung half cross members
are forced inwardly toward each other so that legs 41 and 54 are in
mutual alignment, and legs 39 and 53 are in mutual alignment. A
connecting rod 51, 52, which may be either solid or tubular, is
then inserted in the respective open ends of the aligned half cross
members to thereby connect the two frame half sections and hold
these as a single closed rectangular frame, to be employed in
assembly of the furniture as described below. If deemed necessary
or desirable, a suitable adhesive may be applied to the connecting
rod members 51, 52 or to the frame half sections connected thereby,
prior to this connection of the two U-shaped frame half
sections.
Chair slats or body support members, of which any suitable number,
such as six, for example, may be provided for a single chair, are
formed of the same plastic tubing from which the above described
frame parts are formed. Tubing sections of the desired length are
flattened in a suitable jig and the respective end thereof bent to
form open ended substantially semi circular loops. These loops have
an unstressed inner diameter slightly less than the outer diameter
of the associated furniture cross members. The flattened tubing is
bent to provide a suitable body contour to thereby form both seat
and back of the body support elements. The forming of these body
support elements, just as the forming of all the other parts
described herein, is accomplished while the tubing is heated to a
temperature at which it is workably soft.
In assembly of the completed chair, the several parts are initially
assembled to provide three sub-assemblies. Two of these
sub-assemblies comprise the substantially rectangular cross member
frame full sections 24 and 26 that are initially assembled each
from a pair of identical U-shaped frame half sections as described
above. A second sub-assembly is formed of two side frames and the
upper cross bar 22. As previously described, flattened closed loop
clamping sections 32 and 34 are forcibly spread apart to permit
insertion of the upper cross bar 22 that is clamped therein. If
deemed necessary or desirable, suitable adhesive may be employed to
enhance rigidity of this assembly.
The upper of the two cross member frame full sections 24 is
positioned on a work table that has four apertures respectively
aligned with the four flattened closed loop clamping sections of
the frame 24, such apertures being somewhat larger than the
external diameter of the chair legs. Adjacent cross members of the
rectangular frame section 24 are then forcibly spread apart to
provide a temporary enlargement of each of the flattened closed
loop clamping sections of the rectangular frame 24. The chair legs
10, 12, 14 and 16 are then inserted through a respective one of the
temporarily spread clamping sections of frame 24 and through the
aligned apertures in the work table, until the two side frames and
the upper rectangular frame 24 assume the relation illustrated in
FIG. 1. The temporary enlargement of the clamping sections of the
frame 24 is then released to allow the clamping sections to tightly
grip the respective legs.
The second, lower, cross member frame section 26 is then placed on
the work table, after the apparatus previously partially assembled
has been removed therefrom. The four flattened closed loop clamping
sections of frame 26 are then temporarily spread to allow reception
of the respective chair legs 10, 12, 14 and 16. If deemed necessary
or desirable, suitable adhesive may be applied to the inner surface
of each of the clamping sections to enhance rigidity of the
structure.
The flattened body support members or slats 28, 30 etcetera, are
then snapped in place as illustrated in FIG. 1. This portion of the
assembly is achieved simply by forcing the semi-circular open loop
ends of each slat over a respective one of the associated cross
members. Inherent resilience of the plastic material from which the
parts are formed allow these open looped slat ends to be forcibly
spread apart. This resilience also achieves a clamping of the slat
upon the associated cross member, which clamping is all of the
securement that is necessary in the described arrangement. Although
it is possible to enhance securement of the slats to the chair
frame by use of adhesive, it is preferred to merely secure the
slats by their inherent resilient clamping action so that they may
be readily removed for repair or replacement. Thus the appearance
of the furniture may be quickly and simply changed by replacing
slats of one color with slats of another color, or by rearranging
slats of multiple colors to provide different color patterns.
Although the chair described in connection with FIGS. 1 through 5
is made of widely available inexpensive plastic tubing of a
circular cross section, it will be readily appreciated that tubing
of other cross sections whether non-circular or polygonal, may be
readily employed as deemed necessary or desirable. Thus, as shown
in FIG. 6, the described construction may employ tubing of
substantially triangular section for certain of the furniture
parts, and at least for the legs 10, 12, 14, 16 and upper cross
member 22. Where a leg having a triangular cross section such as
that illustrated at 10a is employed, the several frame full
sections will be formed with flattened closed loop clamping
sections such as that shown at 51a, having a mating triangular
configuration as shown in FIG. 6.
Illustrated in FIG. 7 is a flattened closed loop clamping section
51b for use with furniture having some, or all elements thereof
formed of tubing having a rectangular cross section.
FIG. 8 illustrates a closed loop clamping section 51c also for use
with furniture having some, or all of the structural elements
formed of tubing having a rectangular cross section. However, in
the arrangement of FIG. 8 the rectangular cross section members are
differently oriented than in the arrangement of FIG. 7.
FIG. 9 illustrates an alternate orientation of a closed loop
clamping section 51d for use in furniture having some, or all of
the structural elements thereof formed of tubing having triangular
cross sections.
As can be seen in the illustrations of FIGS. 7 through 9, and as is
the case for all of the closed loop clamping sections described
herein, each flattened closed loop clamping section is formed in
such a size and configuration that, before the insertion therein of
the member to be clamped thereby, it assumes a configuration that
substantially conforms to the exterior configuration of the member
to be clamped, but has dimensions equal to, or somewhat less than
the corresponding dimensions of such clamped member. Thus, with the
clamped member inserted within the closed loop clamping section,
the latter is permanently stressed outwardly thereby and somewhat
resiliently deformed, having its adjacent portions mutually spread
apart, within its elastic limits so as to exert a strong and
effective clamping action upon the member confined therein. This
clamping action is further enhanced by the additional clamping
stresses exerted by the several side frames and cross member frame
sections. These are formed so that, in unstressed condition they
have the parts thereof adjoining the closed loop clamping section
relatively sprung or spread apart. The assembled relation of the
parts is such that the relatively spread apart elements are forced
and held together by an interlocking action of co-operating chair
parts. Even in the absence of adhesive applied to the clamping
sections, a secure and rigid mechanical joint is provided.
It will be readily appreciated that the described furniture
construction may be applied to different types of furniture
arrangements and different overall configurations, the chair
illustrated being shown merely for purposes of exposition. Thus, a
simple foot stool or table may be made, employing principles of the
invention described herein by using only a pair of rectangular
cross frame sections, such as sections 24 and 26 interconnected
only by leg members 10, 12, 14 and 16. Such a table or foot stool
would have a solid or slatted top that could be formed by slats
similar to those indicated at 28 and 30, but of such a shape and
configuration as to extend horizontally between opposed cross
members of the upper of the two rectangular frame sections.
A significant feature of the described furniture construction, in
addition to its light weight, simplicity of forming and low cost,
is the ease of assembly of the several parts without the use of any
special tools. This enables the several parts of the described
chair, or the several sub-assemblies, to be shipped in a relatively
compact package. For example, the two side frames (unassembled to
each other), the two rectangular cross frames, the upper cross
member 22 and the several body support slats may be compactly
packaged for handling and shipment. These components may be readily
assembled by a distribution outlet, or by the consumer himself
without the use of anything more than a screw driver, or the like,
to force apart the substantially closed loop clamping sections for
the described assembly.
There have been described an improved method and apparatus for
furniture construction employing tubular plastic materials that can
be readily worked and which provide improved structural
characteristics by spreading stresses over large areas, all without
the use of any metal fasteners or other reinforcing devices. The
described flattened closed loop clamping joint is resiliently and
elastically expanded during assembly to accept the part to which it
is secured, and is so positioned within the assembly that the
assembly itself and, also, certain stresses involved in normal use,
will urge the joint to exert a tighter gripping action.
The foregoing detailed description is to be clearly understood as
given by way of illustration and example only, the spirit and scope
of this invention being limited solely by the appended claims.
* * * * *