Spring edge for furniture decks

A spring edge for a furniture deck, the deck consisting of a wire fabric deck sheet resiliently supported over a rigid frame, the spring edge consisting of a series of vertically V-shaped spring elements distributed along the forward edge of the frame opening forwardly, with their apices being connected to the deck, each element consisting of a single strand of spring wire configurated to present a horizontally transverse top reach, downwardly and rearwardly inclined legs extending from each end of the top reach to the apex, horizontally transverse torsion legs extending from the lower end of each inclined leg, the torsion legs defining the apex of the element and being secured to the deck, and a forwardly extending bottom leg extending from the opposite ends of the torsion legs and being secured at their forward ends to the frame.

This invention relates to new and useful improvements in spring edges for 
upholstered furniture. 
In upholstered furniture such as sofas and couches wherein loose seat 
cushions are simply laid on and supported by a resilient substructure of 
"deck", it is customary to provide a raised edge along the forward edge of 
the deck. This "edge" has the functions both of preventing the cushions 
from sliding forwardly on the deck, and also of closing and concealing the 
vertical gap or open space which would otherwise appear between the deck 
and the lower front edge of the cushion, especially if the cushions have 
bulging or "crowned" upper and lower faces, as is usually the case. Also, 
the deck, while commonly resiliently yieldable, usually is mounted over a 
rigid frame, and has only thin padding, so that the forward deck edge, 
while padded, is usually very firm, creating a "hard edge" effect which is 
undesirable from the standpoint of maximum comfort. Edging strips 
consisting of lengths of plastic or rubber foam, usually of generally 
triangular cross-sectional contour, have heretofore been used, and do 
provide a padding over the forward frame edge, but are difficult to secure 
in place against the constantly repetitive shifting loads to which they 
are subjected in normal usage, and also do not provide the "depth" or 
distance of yieldability required for greatest comfort. 
The desirability of a greater yieldability "depth" suggests the use of some 
type of edging utilizing springs rather than merely padding, and 
spring-type edges have been proposed, sometimes involving vertically 
V-shaped spring elements spaced along the forward edge of the deck, each 
having its apex secured to the deck, a lower leg extending forwardly and 
affixed at its forward end to the frame, and an upwardly and forwardly 
inclined leg carrying a transverse horizontal border wire defining the 
effective deck edge. In spring elements of this type, it is desirable that 
the element by formed of a single length of spring wire. Elements of this 
general type heretofore used have been subject to certain difficulties. If 
formed in a planar V-form, stress concentration at the apex causes 
work-hardening, crystallization, and early failure. If a horizontal 
transverse leg is inserted between the upper and lower legs, so that 
yielding of the upper leg is accomplished at least partially by torsional 
yielding of the horizontal transverse leg, early failure is reduced, but 
if the wire weight of the upper leg is sufficiently heavy to supply the 
desired torque support of the border wire, the torsion leg must be very 
long to have sufficient torsional yield, preferably as long or even longer 
than the upper leg, to prevent stresses from concentrating at the bends to 
cause early failure. If the torsion leg is sufficiently long, it must be 
secured to the deck along most of its length to guide the upper end of the 
upper leg in a proper vertical path as the edging yields in normal usage, 
and also to prevent the border wire supported by said upper legs from 
tilting or canting in a transverse vertical plane. Such inadequate support 
of the border wire can, in extended usage, cause a wavy, unattractive 
appearance. 
Accordingly, the object of the present invention is the provision of a 
spring-type deck edging which overcomes all of the above enumerated 
shortcomings of prior devices, in that it is formed of a single length of 
spring wire of sufficient weight to support the border wire adequately, 
has torsion legs of sufficient length to avoid stress concentration at the 
wire bends, and has no tendency to cause the border wire to assume a wavy, 
non-straight configuration. Generally, this object is accomplished by 
spacing a series of vertically V-shaped spring elements along the forward 
edge of the deck, each element consisting of a single length of spring 
wire configurated to present a horizontal transverse top reach at the 
upper end of its upper leg, to which the border wire may be affixed, a 
rearwardly and downwarly inclined upper leg extending from each end of 
said top reach to the element apex, a horizontal, transverse torsion leg 
extending from the lower end of each of said upper legs, said torsion legs 
lying in close proximity to each other, and a lower leg extending 
forwardly from the opposite end of each torsion leg, and adapted to be 
secured at its forward end to the seat frame. The torison legs are secured 
to the deck in spaced relation from the frame, by means permitting both 
independent torsional yielding of said torsion legs, and forward and 
rearward sliding relative to the deck. The usual padding is applied over 
the surface defined by the upper legs of the spring elements. 
Other objects are simplicity and economy of construction, and efficiency 
and dependability of operation.

Like reference numerals apply to similar parts throughout the several 
views, and the numberal 2 applies generally to the frame of a seat deck 
for upholstered furniture. Said frame, as shown, is of rigid rectangular 
form, including a front rail 4, rear rail 6, and side rails 8 (one shown). 
The frame may, of course, be of any desired width. 
The deck platform sheet, indicated generally by the numeral 10, consists of 
a front strand 12 and a rear strand 14 which are parallel and extend 
transversely of the seat, and a series of parallel, closely spaced apart 
cross strands 16 extending forwardly and rearwardly between the front and 
rear strands and securely fastened thereto. Each of the front and rear 
strands consists of a spring steel wire core covered by a sheath of soft, 
indentable material such as twisted paper, and the corresponding end 
portion of each cross strand 16, said cross strands constituting spring 
steel wires, is "knotted" about said sheath, as best shown at 18 in FIG. 
2. The sheath provides good purchase for the cross wires on the front and 
rear strands, and also prevents rubbing or grating "wire noises." Front 
strand 12 of the deck sheet overlies the top edge of front frame rail 4, 
and is affixed thereto by staples 20 distributed along the length thereof. 
Rear strand 14 is spaced forwardly of and parallel to rear frame rail 6, 
and is connected thereto by a series of helical springs 22 or other 
resiliently extensible members, hooked at their forward ends around strand 
14, and each hooked at its rearward end into a triangular wire hanger 24 
secured to rear frame rail 6 by staples 26. The size, strength and spacing 
of springs 22 is so selected as to impart the desired degree of resilient 
yieldability to deck sheet 10. Cross wires 16 may be connected together at 
spaced apart points along their lengths, whereby to render their spacing 
uniform, by intermediate strands 28, which may be formed of twisted paper 
or the like, without wire cores, pierced by each of cross wires 16 at its 
point of intersection therewith. 
The spring edge forming the subject matter of the present invention is 
disposed along the forward edge of frame 2, and consists primarily of a 
series of spring elements spaced along said forward frame edge, and each 
designated generally by the numeral 30. Each of said spring elements, as 
most clearly shown in FIGS. 3 and 4, is formed of a single length of 
spring steel wire, and is substantially V-shaped in a vertical plane. The 
central portion of the wire length constitutes a horizontal transversely 
extending top reach 32. Sloping downwardly and rearwardly from each end of 
top reach 32, to the apex of the V-formation, is a wire length forming an 
upper leg 34 of the element. At the lower end of each leg 34, the wire is 
bent to form a torsion leg 36, said torsion legs being substantially 
parallel to top reach 32, and extending oppositely from legs 34 so as to 
be substantially coextensive with top reach 32. Said torsion legs are 
disposed in close juxtaposition to each other, or against each other, and 
define the apex of the V-formation of the spring element. At the end of 
each torsion leg opposite from its associated upper leg 34, the wire is 
bent forwardly to form a lower leg 38 lying substantially in the vertical 
plane of the upper leg associated with the other of the torsion legs, and 
extending forwardly. Adjacent its forward end, each lower leg 38 is curved 
downwardly, as indicated at 40, and at its extreme forward end, the wire 
is bent horizontally inwardly to form a terminal leg 42 which is generally 
parallel to top reach 32. 
In installation, after deck sheet 10 has been applied to frame 2 as shown 
and described, a cover layer 44 formed of natural or synthetic fabric or 
the like, and of a size capable of covering the entire top and vertical 
side edges of the seat, is folded along a line transverse to the seat, as 
indicated at 46 in FIG. 2, whereby to form layers 44A and 44B, and tacked 
to the front face of front frame rail 4 adjacent said fold, as indicated 
at 48. Both layers of the cover are then laid rearwardly over the top of 
deck sheet 10. Spring elements 30 are then spaced as desired along rail 2, 
and terminal legs 42 of said elements are secured to the top edge of rail 
4, forwardly of front deck strand 12, by staples 50, said staples piercing 
both layers of cover 44. The curvatures 40 of lower legs 38 of the spring 
element permit them to extend rearwardly over strand 12. Torsion legs 36 
at the apex of each spring element are then secured to the forwardmost 
intermediate strand 28 of the deck by clips, hog rings, or the like 52, 
which encircle both torsion legs as well as strand 28, and piercing both 
layers of cover sheet 44. At least two clips 52 should be used for each 
spring element, preferably adjacent the respectively opposite ends of the 
torsion legs, but of course should not be so tight as to bind the two 
torsion legs so tightly together as to prevent the relatively opposite 
torsional movements thereof which occur in normal usage. For reasons to 
appear, the attachment of the spring elements to the deck should be 
forwardly and rearwardly slidable, as is permitted by the slidability of 
strand 28 along cross wires 16 of the deck. Alternatively, torsion legs 36 
could be hogringed directly to cross wires 16, with said hog-rings being 
slidable along wires 16. A border wire 54, which may be a paper-sheathed 
spring steel wire in the same manner as deck sheet strands 12 and 14, is 
then extended the full width of the seat at the upper ends of upper spring 
legs 34, and firmly secured to top reaches 32 of the springs by sheet 
metal clips 56. A layer 58 of padding material such as natural or 
synthetic foam or cotton felt is then laid over deck sheet 10 rearwardly 
of spring elements 30, and a similar layer 60 of padding material is laid 
over the top side of upper spring legs 34. Both layers of cover sheet 44 
are led upwardly between the contiguous edges of padding layers 58 and 60. 
Finally, cover layer 44A is pulled forwardly over padding 60 and then 
downwardly in front of and under the lower edge of front frame rail 4, and 
tacked to the inner surface of said rail as at 60. This cover layer may be 
pulled to any desired degree of tension before it is tacked, thereby 
acting on a "tie-down" element providing any desired degree of 
pretensioning of the spring elements, and hence any desired degree of 
relative firmness or yieldability of the raised deck edge formed by said 
spring elements. Similarly, though not shown, cover layer 44B is drawn 
rearwardly over padding 58 and tacked to rear frame rail 6. 
Thus it will be apparent that a spring deck edge assembly having several 
advantages has been produced. It is spring-supported, not merely padded, 
and hence provides a "depth" of yieldability conducive to a high degree of 
comfort. It is rigidly secured to the deck frame by staples 50 and hence 
cannot be disaligned or moved out of position in normal usage. It is 
simple and economical, both in original manufacture and in installation. 
The downward deflection of the elements, as most accurately reflected by 
downward deflection of border wire 54, is accomplished in large degree by 
twisting or torsional deformation of torsion legs 36 of the elements. This 
type of yield, by distributing the strain along a substantial length of 
wire, avoids much of the stress concentration and resultant early failure 
which would occur if the upper and lower legs of the elements laid in the 
same vertical plane and were connected by a sharp bend of the wire. 
Nevertheless, the upper legs 34 of the elements must still flex vertically 
to some degree in the manner of cantilever springs, and must be 
sufficiently stiff to provide the desired degree of support for the border 
wire. It has been found that if the wire is sufficiently heavy and stiff 
to provide the required cantilever strength of upper legs 34, then the 
length of torsion legs 36 must be at least approximately equal in length 
to upper legs 34. Otherwise the torsion legs will be so stiffly resistant 
to twisting yield that dangerously high concentrations of stress will 
still occur at the wire bends at the ends of the torsion legs, and early 
failure may still result. Lengthening the torsion legs increases the leg 
length subject to torsion, and therefore decreases their resistance to 
twisting sufficiently to reduce stress concentration at the bends to a 
safely acceptable level. This approximate equality of length between the 
upper and torsion legs of the spring elements is present in the structure 
as shown, and is an important feature of the present invention. 
With the torsion legs 36 as long as described, it becomes important that 
both torsion legs of each spring element be secured together in closely 
parallel relation along substantially their entire lengths, as is 
accomplished by clips 52. Otherwise, when the spring edge is loaded as in 
normal usage, the torsion legs would become misaligned, by separation or 
angularity thereof, and hence would provide irregular support for border 
wire 54, allowing it to be sinuously and irregularly deformed along its 
length. This would impart an untidy, irregular appearance to the seat 
which would be highly objectionable. Clips 52 maintain torsion legs 36 
substantially parallel to top reach 32 and to terminal legs 42, so that 
top reach 32 is maintained generally parallel to the front edge of frame 2 
at all times. Any sinuous malformation of the border wire, as described, 
is further prevented by the fact that the top reach 32 of each spring 
element, to which said border wire is affixed, is equally supported and 
positioned at both of its ends by the two upper legs 34 of the element. 
Of course, clips 52 should not grip torsion legs 36 so tightly as to 
prevent the relatively opposite torsional yielding of said legs which 
occurs in usage. Otherwise, the advantages of the torsion action would be 
reduced or lost. Therefore, clips 52 engage torsion legs 36 only loosely. 
Also, it is important that whatever means connects torsion legs 36 to deck 
sheet 10 permits forward and rearward movement of said legs relative to 
said deck, since otherwise the spring elements would effectively shorten 
the front-to-rear span of the deck and interfere with the vertical 
yieldability of the deck. Such relative front-to-rear movement of torsion 
legs 36 relative to the deck, here shown as permitted by the slidability 
of strand 28, to which torsion legs 36 are attached, along wires 16 of the 
deck, although it could be provided by other means, renders the respective 
spring actions of the spring edge assembly, and of the deck, substantially 
independent of each other. 
While I have shown and described a specific embodiment of my invention, it 
will be readily apparent that many minor changes of structure and 
operation could be made without departing from the spirit of the 
invention.