Note: Descriptions are shown in the official language in which they were submitted.
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Furniture subframes, such as for upholstered chairs
and sofas, have been commonly fabricated from a number of separ-
ate pieces of wood that are individually shaped by machine, as-
sembled with the aid of jigs of clamps, and then glued, screwed,
or otherwise fastened together. That method of fabrication in-
volves a great deal of labor and does not lend itself to mass
production techniques. Further problems are the greatly in-
creased cost of lumber, the slowness of curing of lumber, the
poor quality of cuttings of lumber, the excessive waste in form-
ing other than straight shapes and the dimensional instability
of cut lumber. The generally limited supply of fine hardwood
; pieces has resulted in subframes of poor quality through sub-
stitution with inferior woodO The use of wood-joining techniques
appropriate for mass production produces weak joints that can
cause premature structural failures. A desirable solution for
these problems would be to provide furniture frames of a light-
weight synthetic material that are suited to assembly line pro-
duction and are less affected than wood in temperature and hum-
idity variations.
According to the invention, a furniture frame comprises
a pair of load-bearing sub-frames composed of a nailable moldable
material having a high density exterior and a lower density in-
terior, each sub-frame of thepair being molded in one piece so
as to comprise a plurality of plate members integrally connected
to each other to provide for each said sub-frame inner and outer
side wall areas and to connect the two wall areas to each other,
the inner side of each sub-frame having an opening leading into
a cavity that extends toward the outer side wall area and is per-
ipherally enclosed by the said material to provide a load-bearing
receptacle integral with the remainder of the sub-frame, each of
at least four cf said plate members having an edge connected to
the periphery of the receptacle to strengthen the receptacle and
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connect it to the remainder of the associated sub-frame; the
sub-frames being adapted to be spaced apart in substantially
parallel mirror image relationship to each other at the opposite
ends of a connecting member having its ends inserted into the
receptacles to interconnect the respective sub-frames for sup-
porting the load of one or more persons sitting between them.
The one-piece, injection molded furniture sub-frame
of the invention is lightweight, will not shrink, swell or dry
out with changes in humidity, and provides ease in handling
and reduced cost of shipment.
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Figure 1 is a perspective view of one embodiment of furniture sub-
frame of the invention.
Figure 2 is a perspective view of another embodiment of furniture
sub-frame of the invention.
Figure 3 is a perspective view of yet another alternate furniture
sub-frame of the invention.
~ ith reference to the drawing, Figure 1 shows a pair of furniture
sub-frames generally indicated by numerals 10 and 20 that may be interconnect-
ed by wooden connecting members 12, 14 and 16 shown in phantom line to form a
sofa bed frame. The sub~frames 10 and 20 are raised from the floor by legs 18
also shown in phantom. Legs, castors and like fittings are connected to the
sub-frames by well-known wood furniture techniques and hardware. The sub-
frames include leg-attachment areas formed by substantially parallel plate
members guch as indicated by numeral 19 that provide bearing surfaces for the
fittings and are appropriately spaced-apart for wood type fasteners. The sub-
frames are injection molded in one-piece from polypropylene structural foam or
other injection-moldable materials, such as polystyrene or high density poly-
ethylene, using simple two-piece molds. Polypropylene structural foam such as
that made from "Pro-fax" (R.T.M.)
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polypropylene resin is preferred since it provides a low cost finished
piece having a high density surface and a low density interior that is
ideal for stapling, nailing or screwing. In addition to the use of
polypropylene structural foam, the subframes are adapted to incorpo-
rate "space-frame" technology in their structural design to enhance
their load-bearing capabilities. They are not a mere duplication of
wooden frames in plastic nor are they designed for a non-supportive
trim function.
As can be seen in Figure 1, the subframes 10 and 20 provide
peripherally-enclosed cavities 22a, 22b and 22c providing load-bearing
receptacles that are integral with the subframes, into which the con-
necting members 12, 14 and 16 are inserted and contained by nailing
or other means. Five-sided box-shaped load-bearing receptacles such
as those shown provide relatively high bearing strength and also a
convenient positive end stop for easy registration in assembly. It `-
is also within the scope of the invention to use deep cavities with
or without stop means. A key feature of the present invention is the
arrangement for connection of the peripheries of the receptacles to
the other portions of the subframes. This arrangement is in effect a
support for a cantilevered beam and therefore must sustain great
stresses. To overcome this stress problem according to the invention,
each receptacle is connected to the remainder of the subframe by at
least four plate portions that are each connected at one edge thereof
to and extend outwardly from the periphery of the receptacle. In
Figure 1 this receptacle is typically illustrated by box 22b having at
least four plate portions, such as 23a, 23b, 23c, 23d, 23e, and 23f,
each connected at one edge to and extending outwardly from the peri-
phery of box 22b, the periphery being defined by the four sides of the
. box 22b. In a five-sided receptacle,
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the fifth side that forms the end of the four-sided periphery for
registration purposes is not considered to be one of the said
four plate portions that are connected at one edge to, and extend
outwardly from, the periphery.
Fig. 2 shows an alternative embodiment of the instant
invention. Furniture subframes shown generally at 30 and 40 will
provide load-bearing structures for a recliner chair. As can be
clearly seen in subframe 30, peripheral load-bearing receptacles
32a and 32b are provided for wooden connecting members 31 and 33
shown in phantom. A peripherally-enclosed cavity 32a is inter-
connected for load-bearing to the remainder of the subframe by at
least four outwardly extending plate portions 34a, 34b, 34c, and
34d. An integral flange 36 provides an adequate support and
fastening area for a recliner mechanism (not shown). Reinforced
areas 38 and 42 are provided for the attachment of castors shown
in phantom. Subframes 30 and 40 are adapted to utilize "space-
frame" technology such as Z sections, gusseted U-channels and
double Z sections to achieve optimum strength and low weight. As
can be seen in both Figs. 1 and 2, the subframes also provide con-
tinuous tacking surfaces such as 28 in Fig. 1 and 44 in Fig. 2on all sides thereof. Fig. 1 also provides a large opening 29
for insertion of upholstering material. Subframes 30 and 40 of
Fig. 2 allow any configuration of soft or hard foam cushion to be
attached to the subframe ~pon surface 46.
Fig. 3 shows another alternative embodiment of the instant
invention. Side subframes shown generally at 50 and 60 cooperate
with back section shown generally at 70 to form the load-bearing
structure for a rocker. Side subframes 50 and 60 provide load-
bearing receptacles 52a, 52b and 52c for connecting members shown
- in phantom. The load-bearing receptacle 52b is connected with
the remainder of the subframe by at least four outwardly extending
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plate portions 54a, 54b, 54c and 54d. sack section 70 is
connected to side subframes 50 and 60 by a spring rod and attach-
ing plate 58. By use of the space frame technology discussed
earlier, the side subframes and back section provide a high
strength, lightweight, load-bearing structure. The side sub-
frames 50 and 60 also provide attaching ~reas 62 and 64 for
various arm configurations. Wide openings 66 are provided for
upholstering purposes. Continuous tacking surfaces shown typi-
cally at 68 are also provided on all sides. Back section 70 pro-
vides bri-dging for unsupported upholstery material, for example,
cotton padding which can be added during upholstering.
Thus, it can be seen that the injection molded struc-
tural foam or the like material provides load-bearing structures
that are lightweight and utilize space-frame technology and
structures to eliminate inherent deficiencies and weaknesses
associated with the construction of wood pieces.
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