U.S. patent number 3,698,150 [Application Number 05/043,521] was granted by the patent office on 1972-10-17 for bipartite tubular molded synthetic resin furniture part with internal reinforcement.
This patent grant is currently assigned to Shell Oil Company. Invention is credited to Victor F. Anderson.
United States Patent |
3,698,150 |
Anderson |
October 17, 1972 |
BIPARTITE TUBULAR MOLDED SYNTHETIC RESIN FURNITURE PART WITH
INTERNAL REINFORCEMENT
Abstract
A bipartite generally tubular molded synthetic resin furniture
part, such as a leg for a chair or table or a chair back assembly.
The furniture part is composed of two complementary molded
synthetic resin tube sections arranged side by side and having
mating longitudinal marginal portions bonded to one another so as
to define a cavity extending longitudinally through the part. One
or both of the tube sections are provided with integral molded
synthetic resin reinforcing formations, such as reinforcing ribs or
flanges, which extend across the cavity at intervals and are bonded
to the opposite tube section in such a way as to reinforce the part
against deformation under the load. Additional reinforcement of the
part may be provided by a metal rod positioned longitudinally
within the cavity and extending through aligned openings in the
reinforcing ribs.
Inventors: |
Anderson; Victor F. (Wenonah,
NJ) |
Assignee: |
Shell Oil Company (New York,
NY)
|
Family
ID: |
21927577 |
Appl.
No.: |
05/043,521 |
Filed: |
June 4, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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797616 |
Feb 7, 1969 |
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Current U.S.
Class: |
297/451.13;
249/188; 297/451.11; 297/452.18; 297/446.1; 52/73 |
Current CPC
Class: |
A47B
91/00 (20130101) |
Current International
Class: |
A47B
91/00 (20060101); E04c 003/00 (); E04c
002/30 () |
Field of
Search: |
;248/188.8 ;52/730-732
;297/440,452,455 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Abbott; Frank L.
Assistant Examiner: Ridgill, Jr.; James L.
Parent Case Text
REFERENCE TO COPENDING APPLICATION
The present application is a continuation-in-part of my copending
application Ser. No. 797,616, filed Feb. 7, 1969 now abandoned.
Claims
I claim:
1. A bipartite tubular molded synthetic resin furniture part with
internal reinforcement comprising:
a pair of complementary molded synthetic resin tube sections
arranged side by side and having mating longitudinal marginal
portions disposed in mutual contact and bonded to one another to
join said tube sections into a unitary tube, said tube sections
together defining a cavity extending longitudinally therethrough
and bounded by interior wall surfaces of said tube sections;
each of said tube sections including a plurality of integrally
molded, plastic reinforcing ribs which project from the interior
wall surface of said tube section and extend across said cavity in
planes generally perpendicular to the longitudinal axis of said
cavity, said plurality of ribs being spaced along the length of
said cavity and having projecting end edges which are seated
against and bonded to the interior wall surface of the other tube
section;
the projecting ends of all of said ribs also having openings formed
therein which are aligned longitudinally of said cavity; and
a metal reinforcing rod extending longitudinally within said cavity
and being received by all of said rib openings, the tube
cooperatively formed by said pair of tube sections also having
interior end surfaces which are engaged by respective ends of said
metal reinforcing rod;
whereby said reinforcing rod is effective to support a portion of
any axial load placed upon said tube as well as reinforcing said
tube against bending.
2. A furniture part as claimed in claim 1 wherein said rib openings
comprise slots which open through the projecting end edge of each
of said ribs, whereby said tube sections may be assembled together
about said reinforcing rod by placing all of said ribs into
straddling relationship with said reinforcing rod.
3. A furniture part as claimed in claim 1 wherein the ribs on one
tube section alternate with the ribs on the other tube section.
4. A furniture part as claimed in claim 1 wherein each of said tube
sections is generally triangular in cross-section, and said tube
sections together form a tube of generally rectangular
cross-section.
Description
Reference is also made herein to my application Ser. No. 677,153,
filed Oct. 23, 1967, and entitled "PREFABRICATED PLASTIC CHAIR AND
ASSEMBLY METHOD," now U.S. Pat. No. 3,455,605.
BACKGROUND OF THE INVENTION
1. Field of the Invention:
This invention relates generally to the field of synthetic resin
furniture and more particularly to a hollow molded synthetic resin
part for such furniture.
2. Description of the Prior Art:
Recent developments in synthetic resin material and synthetic resin
molding techniques have made possible the mass production of
synthetic resin furniture which is practical, aesthetically
pleasing, and presently favored by ever increasing popularity and
demand. A primary advantage of synthetic resin furniture over
conventional wooden furniture, of course, resides in the fact that
virtually any furniture style, from the very simple to the highly
ornate, may be mass produced at relatively low cost. Moreover, the
coloring and surface texture of synthetic resin furniture may be
readily varied to simulate virtually any furniture wood and surface
finish.
Generally speaking, the mass production of an article of furniture
involves two basic operations. These are fabrication of the various
parts of the article and assembly of the parts into a unitary
furniture structure. The present invention is concerned with the
fabrication of certain synthetic resin furniture parts which may be
assembled with other parts to provide a completed article of
furniture. As will become evident from the ensuing description, the
invention may be embodied in various kinds of furniture parts.
However, the invention is concerned primarily with and will be
disclosed in relation to synthetic resin parts for chairs and
tables, such as chair and table legs and chair back assemblies.
SUMMARY OF THE INVENTION
According to its broader aspects, the invention provides a
reinforced generally tubular synthetic resin furniture part
comprising a pair of complementary molded tube sections; at least
one of said tube sections having a generally U-shaped cross
section, the legs and the web portion being of generally equal wall
thicknesses as is the web portion of the other of said tube
sections; predetermined surfaces on each of the tube sections for
providing permanent connection between said tube sections; and
means integral with at least one of said tube sections extending
across the cavity between the tube sections for reinforcing said
tube sections. The sections are joined to one another in any
convenient way, as by adhesively bonding, solvent welding, or
ultrasonically welding the predetermined surfaces. The
predetermined surfaces of the tube sections are shaped to mate in
such a way that the joints between the tube sections are virtually
invisible, except perhaps by extremely close inspection. When thus
assembled, the tube sections define a cavity extending
longitudinally through the furniture part and bounded by inner wall
surfaces of the tube sections. The exterior wall surfaces of the
tube sections may be ornately contoured and/or embossed to simulate
any desired furniture style, surface finish, or surface texture.
The color of the synthetic resin material from which the tube
sections are molded may be selected to simulate any furniture wood
and finish.
An important feature of the invention resides in novel reinforcing
means for reinforcing the furniture parts against deformation under
load. This reinforcing feature permits reduction of the wall
thickness of the molded synthetic resin tube sections and thereby
enables production, at minimum cost, of furniture parts conforming
to virtually any furniture style. According to this feature of the
invention, one or both tube sections are integrally formed or
molded with reinforcing formations, such as reinforcing ribs or
flanges, which project from the inner wall surfaces of the
respective sections across the longitudinal cavity defined by the
tube sections, to the inner wall surfaces of the opposite section.
The contacting surfaces of the reinforcing formations and tube
sections are bonded to one another in such a way that the completed
furniture part possesses great strength in spite of its hollow thin
walled construction.
A variety of reinforcing configurations are disclosed. In certain
disclosed embodiments, the reinforcing formations comprise ribs
which are disposed in planes transverse to and spaced along the
longitudinal axis of the part. In one of these embodiments, the
reinforcing action of the ribs is aided by a metal rod which
extends through openings in the ribs. Other disclosed embodiments
of the invention utilize reinforcing flanges disposed in
longitudinal planes of the furniture part.
As noted earlier, the invention may be embodied in various types of
furniture parts. The particular inventive embodiments disclosed
herein are chair and table legs. One disclosed embodiment is an
entire back assembly for a chair including two rear legs and a back
rest.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a plastic chair embodying molded
synthetic resin furniture parts according to the invention which,
in this instance, are the front chair legs and the chair back;
FIG. 2 is an enlarged section through one of the front chair legs
taken on line 2--2 in FIG. 1;
FIG. 3 is an exploded fragmentary perspective view of the front
chair leg;
FIG. 4 is an enlarged section through the chair back taken on line
4--4 in FIG. 1;
FIG. 5a is an enlarged section through one of the rear chair legs
taken on line 5a --5a of FIG. 1;
FIG. 5b is a section taken on line 5b --5b of FIG. 1;
FIG. 6 is a fragmentary exploded perspective view of a modified
molded synthetic resin furniture part according to the
invention;
FIG. 6a is an enlarged sectional view of the embodiment shown in
FIG. 6;
FIG. 6b is an enlarged sectional view of the predetermined surfaces
to be connected shown in FIG. 6;
FIG. 7 is a fragmentary exploded perspective view of a further
modified molded synthetic resin furniture part according to the
invention;
FIG. 7a is an enlarged sectional view of the embodiment shown in
FIG. 7;
FIG. 8 is a fragmentary exploded perspective view of a further
modified molded synthetic resin furniture part according to the
invention;
FIGS. 9 through 11 illustrate the manner of assembling the two
sections of the furniture part illustrated in FIG. 8;
FIG. 12 is a fragmentary exploded perspective view of a further
modified molded synthetic resin furniture part according to the
invention;
FIG. 13 is a section through the assembled furniture part of FIG.
12;
FIG. 14 is a fragmentary perspective view of a synthetic resin
table embodying molded synthetic resin furniture parts according to
the invention which, in this instance, are the table legs;
FIG. 15 is an enlarged side elevation of one of the table legs;
FIG. 16 is an enlarged section taken on line 16--16 in FIG. 15;
FIG. 17 is an exploded fragmentary perspective view of the upper
end of the table leg illustrated in FIG. 15;
FIG. 18 is a section taken on line 18--18 of FIG. 15;
FIG. 19 is a perspective view of a further modified molded
synthetic resin furniture part or leg according to the
invention;
FIG. 20 is an exploded perspective view of the leg illustrated in
FIG. 19;
FIG. 21 is an upper end view of the furniture leg illustrated in
FIG. 19;
FIG. 22 is a perspective view of a further modified molded
synthetic resin furniture part or leg according to the
invention;
FIG. 23 is an upper end view of the leg illustrated in FIG. 22;
FIG. 24 is an exploded perspective view of the leg illustrated in
FIG. 22;
FIG. 25 is an exploded fragmentary perspective view of a further
modified molded synthetic resin furniture part or leg according to
the invention embodying a central reinforcing rod;
FIG. 26 is an exploded upper end view of the furniture leg
illustrated in FIG. 25;
FIG. 27 is an upper end view of the assembled furniture leg of FIG.
25; and
FIG. 27a is an enlarged fragmentary section taken on line 27a --27
a in FIG. 27.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring first to FIGS. 1 through 5b of these drawings, there is
illustrated a synthetic resin chair 10 embodying molded plastic
parts 12 and 14 according to the invention. In this instance, parts
12 are the front chair legs and part 14 is the back assembly for
the chair. The front legs and back assembly are attached to the
front corners and rear side, respectively, of a molded plastic seat
frame 16. This seat frame carries a seat cushion 18. Front legs 12
and back assembly 14 may be attached to the seat frame in any
convenient way. One manner of affecting this attachment is
disclosed in the aforementioned U.S. Pat. No. 3,455,605. According
to the disclosure of the latter patent, attachment of the legs and
back to the seat frame is accomplished by providing the legs and
back with integral molded lug formations which fit snugly within
complementary slots in the seat frame and are bonded to the
frame.
The front chair legs 12 are mirror images of one another and each
comprises a pair of relatively thin walled complementary synthetic
resin tube sections 20 and 22. These tube sections are arranged
side by side and have mating longitudinal marginal portions 24
disposed in mutual contact and joined in any convenient way. By way
of example, the contacting margins 24 of the tube sections may be
solvent welded. The tube sections 20, 22 define a cavity 26, FIG.
2, extending longitudinally through the part and bounded by inner
wall surfaces 28 of the tube sections. The tube sections have
exterior wall surfaces 30 which may be contoured and/or embossed to
simulate various furniture styles. In this instance, the exterior
wall surfaces of the tube sections are shaped to simulate a simple
tapered furniture leg.
In the particular chair leg configuration under discussion, the
tube sections 20, 22 have similar, generally channel shapes in
transverse cross-section. Each tube section includes two leg
portions, a side wall member 32 and a flange 34 disposed in spaced
parallel longitudinal planes of the leg and a web portion 36
extending between and integrally joining the wall member and
flange. The side wall member 32 of each tube section is flush with
its adjacent edge of the web portion 36. The opposite edge of the
web portion projects beyond the flange 34 a distance approximating
the thickness of the side wall member to provide a longitudinal
ledge or shoulder 38 on each tube section. As shown, the tube
sections 20, 22 of each leg are assembled in such a way that the
side wall members 32 of each section abut the shoulder 38 on the
opposite section and overlap, in face to face contact, the flange
34 on the opposite section.
As noted earlier, a feature of the invention is concerned with
reinforcement of the present furniture part or leg to enable the
latter to have an economical hollow thin walled molded synthetic
resin construction and yet possess sufficient strength and rigidity
to resist deformation under load. In the particular inventive
embodiment under discussion, the side wall members 32 and web
portions 36 of the tube sections 20, 22 provide the main body of
the leg and the tube section flanges 34 effectively serve as
reinforcing formations or flanges. The longitudinal edge of each
flange fits snugly into a groove 40 in the inner wall surface of
the opposite tube section. This groove of each tube section is
defined by its side wall member 32 and a longitudinal rib 42
projecting from the inner wall surface of the tube section in
spaced parallel relation to the wall member. It will be observed
that these interfitting flange and groove configurations serve to
positively locate the tube sections laterally relative to one
another.
As has been mentioned earlier, the tube sections 20 and 22 may be
joined by a convenient joining technique, such as solvent welding.
It is also to be understood that other forms of joining may be
used, such as ultrasonic welding, inert gas welding, or hot
stacking, depending upon the particular cross-sectional
configuration used for the furniture leg, as will be discussed in
more detail hereinbelow. The cross section illustrated in FIGS. 2,
3, 4, and 5 are uniquely designed for being joined by solvent
welding. In solvent welding certain nonvisible surfaces are wetted
with a solvent which is highly active with a particular synthetic
resin material to be joined. The solvent actually dissolves a
portion of the synthetic resin on the joint surfaces. When the
wetted, partially dissolved surfaces come together, mixing of the
surfaces occur combining the synthetic resin of one part to that of
the other. After predetermined contact pressure has been applied
along the joint and a precalculated curing time allowed, a fixed
joint will be achieved that approaches 100 per cent of the strength
of the part material.
For example, referring to FIG. 3, surface 24' of flange 34 of tube
section 22 is wetted as is the surface 24" of the side wall member
32 of the tube section 22. In addition, the surfaces defining the
groove 40 are also coated as are the extended edges of both the
flange and the side wall member. In a like fashion, the
corresponding members of the tube section 20 are also coated and
two tube sections 20 and 22 are brought together to cause a
permanent joint so as to form a configuration as shown in FIG. 2.
In order to provide room for synthetic resin material which may be
squeezed during the time that pressure is applied, the side wall
member 32 on each of the two sections is made slightly shorter than
the flanges 34 so that when pressure is applied there is a flowing
of the synthetic resin material to fill the slight gap provided
between the ends of the side wall members and the shoulders 38.
This gap will become filled during the process which forms the
unitary furniture part. Because of the substantial surface areas of
the tube sections in abutment which become bonded, the resultant
furniture part is a high strength but economical element. It is, of
course, understood that the cross sections shown in FIGS. 2, 4, and
5 will not have distinct boundary lines but rather tend to form a
unitary piece without a clear indication of where the tube section
20 ends and where the tube section 22 begins; nevertheless, for
purposes of clarity, the cross-sectional drawings are made with
distinct boundaries.
The rear molded plastic furniture part or chair back assembly 14
comprises two complementary molded synthetic resin back sections 44
and 46, FIGS. 1, 4, 5a, and 5b, arranged side by side. These
complementary back sections include lower tube sections 48 and 50,
FIGS. 5a and 5b, which form rear chair legs 51, upper generally
annular tube sections 52 and 54, FIG. 4, which form a back rest
frame 55, and an ornamental insert 56 within and joined to the
frame to provide with the frame a back rest. Insert 56 has a cross
section like that shown in FIG. 2. Referring to FIGS. 4 - 5b, it
will be seen that the chair back tube sections 48, 50, 52, 54 are
similar in transverse cross section to the tube sections 20, 22 of
the front chair legs 12 and mate in the same manner as the latter
legs. Accordingly, it is unnecessary to re-describe the back tube
sections in detail. Suffice it to say that these back tube sections
are secured to one another in the same manner as the front leg tube
sections so as to join the back sections 44, 46 into a unitary
chair back structure. The ornamental insert 56 of the chair back
may be separately formed and secured in place within the chair back
frame. Alternatively, this insert may be molded in one piece,
integral with one of the chair back sections, or in two mating
portions integral with the two chair back sections, as desired.
FIGS. 6 - 13 illustrate various alternative molded synthetic resin
configurations according to the invention which may be employed in
the front chair legs 12 and/or the chair assembly back 14 of FIG.
1. The molded synthetic resin furniture part 100 of FIG. 6
comprises a pair of complementary molded plastic tube sections in
the form of a channel section 102 and a cap strip section 104. The
channel section 102 has parallel side walls 106 integrally joined
along one longitudinal edge by the web portion 108. The two side
walls 106 have grooves 109 and 110 formed in the ends thereof which
mate with projections 111 and 112, respectively, of the cap strip
section 104. As more clearly illustrated in FIG. 6b, the projection
112 is purposely made longer and narrower than the groove 110. In
addition, surfaces 112" and 110" are slightly oblique so as to
provide a V-shaped groove. The groove will be located on the inside
of the furniture part. The greater length of the projection 112
insures intimate contact of the tube sections and there is
sufficient room for the flow of excess material with squeeze out
being directed to the groove on the inside of the furniture part so
as to retain an unmarred outer surface.
While any suitable joining technique may be used for the
configuration shown in FIG. 6, it has been especially designed for
ultrasonic welding. This welding technique is accomplished through
the use of high frequency vibrations between two parts of similar
material; the high frequency vibration is controlled and
transmitted through a special transducer head cone, the size,
shape, type, and location of which control the finished weld. The
degree of synthetic resin melt is achieved as a result of the
frequency of vibration and the thickness of the parts being
connected. The parts must be maintained in intimate and accurate
contact throughout the welding operation to effect a good bond. As
mentioned, the additional space created by the groove 110 allows
the melted material to flow in a predetermined manner during the
welding operation so that after the joining technique is finished a
bonded connection is made, such as shown in FIG. 6a and the second
part of FIG. 6b.
Furniture part 100 is provided with internal reinforcing formations
114 which extend across the cavity 116 within the part. In this
instance, the reinforcing formations comprise an integral molded
plastic reinforcing rib or flange 118 of generally zig-zag shape
which projects from the inner wall surfaces of the cap strip
section 104, and transverse reinforcing ribs 120 integral with and
extending laterally of the reinforcing flange within each of the
interior angles defined by the flange. Ribs 120 are disposed in
planes normal to and spaced along the longitudinal axis of the
furniture part.
The reinforcing flange 118 and ribs 120 are so dimensioned that
when the channel and cap strip tube sections 102, 104 are
assembled, the reinforcing flange and ribs fit snugly between the
channel section side walls 106 and abut the inner wall surface of
the channel section web portion 108. To achieve additional
strength, the contacting surfaces of the reinforcing flange and
ribs and the channel section may be bonded to one another to form a
rigid synthetic resin furniture part. Bonding may be accomplished
by ultrasonic welding or solvent welding techniques.
The synthetic furniture part 200 of FIG. 7 is similar to that of
FIG. 6 in that part 200 has a pair of molded synthetic resin tube
sections in the form of a channel section 202 and a cap strip
section 204, respectively. Channel section 202 has parallel side
walls 206 integrally joined along one longitudinal edge by a web
portion 208. Cap strip section 204 is laterally dimensioned to seat
against the opposite longitudinal edges of the channel side walls
206 so as to close the open side of the channel section. The
lateral edges 205 and 207 of the cap strip section 204 are oblique
as are the extended edges 201 and 203 of the side walls 206. When
brought together, the channel section 202 and cap strip section 204
form lateral longitudinally extending grooves which are uniquely
designed for still another joining technique than the two already
mentioned. For example, the FIG. 7 embodiment may be permanently
connected by an inert gas welding technique. Inert gas welding is
quite similar to conventional metal welding in that a synthetic
resin welding rod of the same material that is to be joined is laid
within the two lateral grooves and is melted. Neither the rod nor
the part to be welded are totally melted; only a shallow section of
the rod and the part surfaces reach the melting temperature. It is
the contact pressure of the rod's outer surface that causes the
contact between the parts and the rod. Thus, prior to welding a
configuration as shown in FIG. 7a will exist, and after welding and
finishing the outer surface of the side walls will be completely
flush, providing an aesthetically beautiful furniture part.
Plastic furniture part 200 is provided with reinforcing formations
210. In this instance, the reinforcing formations comprise
reinforcing flanges 212 integrally molded on the inner wall surface
of the cap strip section 204. Flanges 212 are disposed in spaced
longitudinal planes of the part parallel to the side walls 206 of
the channel section 202. These flanges project across the central
cavity 214 in the part into contact with the inner wall surface of
the web portion 208 of the channel section. Formed in the inner
wall surface of the web portion, are longitudinal grooves 216 which
snugly receive the longitudinal edges of the reinforcing flanges.
The contacting surfaces of the reinforcing flanges and channel web
portion may be bonded to one another to provide a strong, rigid
synthetic resin furniture part.
Turning now to FIGS. 8 - 11, the illustrated synthetic resin
furniture part 300 comprises molded synthetic resin channel and cap
strip tube sections 302, 304 which are similar to those of FIG. 6.
Part 300 has reinforcing formations 306 in the form of separate
reinforcing ribs 308 which are integrally molded on the inner wall
surface of the cap strip section 304. These reinforcing ribs are
disposed in planes normal to and uniformly spaced along the axis of
the central cavity 310 through the part 300. Reinforcing ribs 308
are dimensioned to fit snugly between the side walls 312 of the
channel tube sections 302 and to seat against the inner wall
surface of the channel web portion 314.
In this particular embodiment, attachment of the channel and cap
strip sections is provided by synthetic resin rivet posts 316 which
are integrally molded on the inner wall surface of the channel web
portion 314 and terminate in rivet-like ends or tips 318. When the
channel and cap strip sections are assembled, these rivet tips
project through externally counter-sunk holes 320 in the cap strip
section 304. After assembly of the channel and cap strip sections,
pressure and heat are applied to the protruding rivet tips 318 so
as to form a flush configuration, shown in FIG. 11.
As with the FIG. 7 embodiment, the extended ends of the side walls
312 have oblique surfaces 313 and 315 while the lateral edges of
the cap strip section 304 have oblique surfaces 301 and 303.
However, unlike the FIG. 7 embodiment, the corresponding surfaces,
such as 301 and 313, complement each other to form an abutment so
that the surfaces 301 and 313 lie in an oblique plane which
intersects a corner of the finished furniture part. By being so
constructed, the boundary line between the two sections become
nearly invisible. Additionally, the surfaces, such as 301 and 313,
may be bonded to one another, such as by solvent welding, to
additionally hold the two sections in rigid connection.
FIGS. 12 and 13 illustrate a modified synthetic furniture part 400
according to the invention which is identical to the furniture part
300 of FIGS. 8 - 11 with two exceptions. First, both the channel
tube section 402 and the cap strip tube section 404 of the part 400
are formed with reinforcing ribs 406. These ribs are arranged in
alternate sequency along the axis of the cavity 408 through the
furniture part. Secondly, the cap strip section 404 is provided
with integral molded plastic sleeves 410 which project from the
inner wall surface of the strip section and receive rivet posts 412
on the channel section 402 when the sections are assembled. After
assembly, the protruding tips 414 of the rivet posts are deformed
by the application of heat and pressure, in the same manner as
discussed in connection with the synthetic resin furniture part of
FIGS. 8 - 11.
Referring now to FIGS. 14 - 18, there is illustrated a further
modified synthetic resin furniture part according to the invention
which, in this instance, is a leg 500 for a table 502. Leg 500 has
two complementary molded synthetic resin tube sections, a channel
section 504 and a cap strip section 506 arranged side by side with
mating longitudinal marginal portions 508 of the sections in
contact. As in the previous embodiments of the invention, the tube
sections may be joined by adhesively bonding, inert gas welding,
solvent welding, or ultrasonically welding their contacting
marginal surfaces. When thus assembled, the tube sections define a
cavity 510 extending longitudinally through the leg. Integrally
molded on the inner wall surfaces of the tube sections are
reinforcing ribs 512 which extend across the cavity and seat
against and which may be bonded to the opposite tube section, as
before.
It will be observed that the channel section 504 has a generally
channel shape in transverse cross section and the cap strip section
506 is essentially a cap strip which closes the upper side of the
channel section. From this standpoint, the table leg 500 is
generally similar to the furniture parts or chair legs described
earlier. However, the external wall surfaces of the table leg are
shaped to provide the leg with a French provincial design. As a
consequence, the channel section 504 has an arcuate cross section
which varies along the leg from a relatively deep arcuate channel
shape at the lower end of the leg to a relatively shallow arcuate
channel shape at the upper end of the leg. The cap strip section
506 also has an arcuate cross section which varies along the leg
from an externally convex shape at the lower end of the leg to an
externally concave shape at the upper end of the leg.
In the particular table leg illustrated, the mating longitudinal
marginal portions 508 of the channel and cap strip sections 504,
506 comprise laterally thickened wall portions 514 on the channel
section, along its longitudinal edges. These thickened wall
portions form recesses 516. The recesses 516 receive mating
longitudinal beads or tongues 518 which are integrally molded on
the cap strip section along its longitudinal margin. Referring to
FIGS. 16 and 18, it will be observed that the longitudinal marginal
portions 508 of the tube sections mate or engage in a manner such
that the external wall surfaces of the tube sections are flush with
one another along the marginal joints between the sections so as to
render these joints virtually undiscernible, except perhaps by
extremely close inspection.
Table 502 has a frame 520 to which the upper end of the table leg
500 is attached. This attachment may be accomplished in various
ways. In the particular embodiment shown, an insert 522 with
threaded studs 524 is contained within the upper end of the leg
cavity 510. The studs 524 protrude through holes (not shown) in the
confronting upper portion of the cap strip section 506. As already
noted, this upper portion of the cap strip section has an
externally concave and hence an internally convex arcuate shape in
transverse cross section. The upper portion of the channel section
504, on the other hand, has an externally convex and hence
internally concave arcuate shape in transverse cross section. As a
consequence, the upper end of the leg cavity 510, which receives
the insert 522, has an arcuate cross section. The insert 522, which
may comprise a molded synthetic resin, foam synthetic resin, or
filled wood part, has the same arcuate shape in transverse cross
section as the leg cavity and thus complements the cavity. The
inner concave surface 528 of the insert seats flush against the
inner concave wall surface 530 of the cap strip section so as to
provide extensive face to face contact between these parts.
The upper external concave wall surface 532 of the cap strip
section 506 seats flush against a mating side surface on the table
frame 520 when the leg is assembled on the frame. The studs 524 of
the leg insert extend through openings in the frame and receive
nuts (not shown) which are tightened against the inner sides of the
frame to firmly attach the leg to the frame. In this regard, it
will be understood that the face to face contact of the upper
portion of the cap strip section 506 with the table frame 520 and
the leg insert 522 prevents deformation of the leg when the nuts
are tightened and thereby assures firm attachment of the leg to the
frame. Referring to FIG. 17, it will be seen that the cap strip
section is also enlarged to provide an upwardly presented shoulder
536 just below its upper concave, table frame seating surface. This
shoulder seats against the under side of the table frame to
vertically support the frame and resist lateral rotation of the leg
relative to the frame.
FIGS. 19 - 24 illustrate modified synthetic resin table legs 600
and 602 according to the invention which are generally similar to
the table leg 500, just described. The table legs 600, 602 differ
from the legs 500 in that the external wall surfaces of the
modified leg are shaped to conform to contemporary designs, rather
than a French provincial design. Also, the fastening means for
securing the modified legs to the table frame comprise tapered
attachments lugs 604 which are integrally molded on the upper
concave table frame seating surfaces 606 of the cap strip tube
sections 608, 609 of the legs. These lugs are adapted to fit snugly
within mating tapered grooves in the table frame and to be force
fitted or bonded to the frame. The leg tube sections have alternate
reinforcing ribs 610.
Turning now to FIGS. 25 - 27, there is illustrated a modified
synthetic resin furniture leg 700 according to the invention which
may be utilized, for example, as either a chair leg or a table leg.
The synthetic resin furniture part or leg 700 comprises two
complementary molded synthetic resin tube sections 704, 706. In
this instance, the tube sections are generally triangular in cross
section and mate in such a way as to provide a furniture leg of
rectangular cross section. The external wall surfaces of the tube
sections are quite plain and provide a leg of simple tapered
configuration. It will be understood, of course, that the furniture
leg 700 may have any cross-sectional shape and conform externally
to any desired furniture style.
Projecting from the inner wall surfaces and beyond the confronting
open sides of the tube sections 704, 706 are a number of integral
molded synthetic resin reinforcing ribs 708. These ribs are
disposed in planes normal to and spaced along the longitudinal axis
of the leg. When the tube sections 704, 706 are assembled, the ribs
708 project across the cavity 710 through the leg into contact with
the opposite tube section. As in the previous embodiments of the
invention, the tube sections are joined to one another, as, for
example, by bonding to one another the mating longitudinal marginal
portions of the tube sections and the contacting inner wall
surfaces of the sections and the reinforcing ribs.
The reinforcing ribs 708 of the tube sections 704, 706 alternate.
Moreover, these ribs are spaced along the axis of the leg 700 in
such a way that when the tube sections are assembled, the
corresponding ribs on the sections overlap in face to face contact.
Leg reinforcing means 702 comprise a metal reinforcing rod 711 with
end flanges or heads 712 which is positioned longitudinally within
the leg cavity 710 and extends through aligned rib openings 714 in
the reinforcing ribs 708. In this instance, the rib openings 714
comprise slots which open longitudinally through the outer edges of
the ribs and overlap one another at their closed ends to
effectively define a circular rod receiving opening. As shown in
FIG. 27a, the rod end flanges 712 project edgewise into laterally
opening grooves in the tube sections 704, 706, whereby the rod
supports a portion of the axial load on the furniture part. The rod
thus reinforces the part axially as well as against bending. It
will be understood that the open ended slot configuration of the
reinforcing rib openings 714 permits the tube sections 704, 706 to
be assembled about the reinforcing rod 702. In this latter
connection, it will be observed that in the particular inventive
embodiment shown, as well as in all of the other disclosed
inventive embodiments, the complementary tube sections are shaped
to be brought into mating assembled engagement by relative assembly
movement of the sections along direction lines transverse to the
length of the furniture part or leg. It would also be possible to
insert a series of filament fiber lines into the location of the
rod 711 while under tension, thus increasing the load carrying
strength beyond a metal rod support.
In the particular furniture leg 700 selected for illustration in
FIGS. 25 - 27, normally inner or rear tube section 704 is formed
with integral molded synthetic lugs 716 to fit within and be bonded
to mating grooves in the furniture frame 718 for attaching the leg
to the frame. The normally outer or front tube section 706 has a
V-shaped upper end 720 which projects above the upper end of the
tube section 704 and is adapted to fit about the corner of the
frame in the manner shown.
What has been described more generally are furniture pieces or
parts made up of two tube sections which have predetermined
surfaces which are bonded to achieve a unitary, rigid and strong
furniture part. As mentioned, there are several techniques for
connecting the two tube sections together with unique designs
favoring one or the other of the joint techniques. The designer of
a piece of furniture will choose whichever technique and
corresponding structure is most economical and suitable for the
particular style that he is concerned with.
In each embodiment of the invention, the cavity through the molded
synthetic resin part may be filled with foam synthetic resin or
other filler material similar to the insert 522, FIGS. 16 and 17,
to provide the part with a solid sound and feel resembling a wood
part.
It will be immediately evident to those versed in the art that a
hollow, split molded synthetic resin furniture part according to
the invention has numerous inherent advantages over a solid, one
piece molded part. Among the foremost of these advantages are the
following:
1. Individual parts will weigh substantially less.
2. Initial part costs will be greatly reduced by reducing the
amount of material used in and reducing the production cycle time
(cycle time reduction is obviously due to quantity of material that
must fill the mold cavity and the time required for preliminary
cooling).
3. Section modular strength is greater in a hollow cross section
than a solid cross section.
4. There is less material wasted in a rejected part.
5. As part of the art of injection molding, equal wall thickness
produces parts with a minimum of internal stresses developed during
the molding operation and cooling.
6. Hollow parts will more closely equal the weight of wood.
7. Hollow parts will not warp as readily as thick solid
sections.
8. Injection molding equipment required to produce two piece hollow
parts will need less mold clamp pressure and less pressure need to
squeeze the injecting synthetic resin into the mold.
The invention has been described in considerable detail in order to
comply with the patent laws by providing a full public disclosure
of at least one of its forms. However, such detailed description is
not intended in any way to limit the broad features or principles
of the invention, or the scope of patent monopoly to be
granted.
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