U.S. patent number 3,774,967 [Application Number 05/268,870] was granted by the patent office on 1973-11-27 for seating and sub-assembly for seats and backs.
Invention is credited to David L. Rowland.
United States Patent |
3,774,967 |
Rowland |
November 27, 1973 |
SEATING AND SUB-ASSEMBLY FOR SEATS AND BACKS
Abstract
Seats and backs for chairs and other seating units are made as a
sub-assembly of sinuous spring wires. For example, a rim, typically
having straight ends joined by usually parallel sides shaped as
circular arcs, encloses, and its straight ends are attached to, the
opposite ends of each of a series of the sinuous spring wires,
which extend between them in a circular arc paralleling those of
the rim sides. Each of the two extreme spring wires is preferably
tangent at each cycle to one of those sides, and each wire touches
its adjacent wire at least once per cycle. A thin sleevelike
plastic coating surrounds the wires and follows their sinuous
shape. It also surrounds the rim and links the wires and the rim
together and links the wires themselves together wherever they
touch, into a unitary assembly shaped as a cylindrical arc and
intended to be flattened somewhat when installed on a chair frame,
to place the springs in tension along a flatter cylindrical arc.
The ends serve to mount the assembly on the frame, and the parallel
sides enclose the springs and minimize their catching on clothing,
while the tension provides one of the main forces retaining the
assembly in place. In preferred forms of the invention the plastic
coating has an A-scale Shore durometer between 45 and 90, so that
the assembly is held together by the plastic coating without
substantially restraining the flexing of the spring wires, while
the coating also provides a spring action itself between the
adjacent wires, by stretching and contracting, giving a two-way
stretch.
Inventors: |
Rowland; David L. (New York,
NY) |
Family
ID: |
22426794 |
Appl.
No.: |
05/268,870 |
Filed: |
July 3, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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126808 |
Mar 22, 1971 |
3720568 |
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Current U.S.
Class: |
297/447.3;
297/452.64; 160/44; 160/404; 267/111; 297/447.4; 297/448.1 |
Current CPC
Class: |
A47C
7/30 (20130101); A47C 7/282 (20130101); A47C
5/06 (20130101); A47C 7/16 (20130101); A47C
7/285 (20130101); D01H 7/048 (20130101); Y10T
428/12333 (20150115); Y10T 428/24008 (20150115) |
Current International
Class: |
A47C
7/28 (20060101); A47C 5/00 (20060101); A47C
5/06 (20060101); A47C 7/02 (20060101); A47C
7/16 (20060101); D01H 7/02 (20060101); D01H
7/04 (20060101); A47c 007/00 (); A47c 007/14 () |
Field of
Search: |
;297/56-57,445,452,457
;267/111 ;5/353,354 ;160/403,404 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Nunberg; Casmir A.
Parent Case Text
This is a division of application Ser. No. 126,808, filed Mar. 22,
1971 now U.S. Pat. No. 3,720,568.
Claims
What is claimed is:
1. A seating apparatus, including in combination:
a. a frame having at least two spaced-apart rigid frame
portions,
b. an assembly having
1. a series of arcuate, continuous, sinuous wires, each having two
ends, each said wire closely approaching each of its immediately
adjacent said wires at frequent intervals,
2. fastening means firmly securing said wires adjacent their ends
and positively preventing relative movement of the wires to said
fastening means, and
3. a thin sleevelike plastic coating surrounding said wires and
said fastening means, following the sinuosity of said wires and
joining said wires together where they closely approach each other,
said approaches being close enough for effective bridging between
them by said coating,
whereby said wires, fastening means, and plastic coating comprise a
unitary assembly defining a cylindrical arc, and
c. mounting means for securing said assembly to said rigid frame
portions across a space that flattens said arc to a flatter arc and
places said assembly in tension.
2. The seating apparatus of claim 1 wherein said frame supports two
said assemblies, one for a seat and one for a back.
3. The seating apparatus of claim 2 wherein said seat arches
upwardly from side to side and back arches rearwardly from side to
side.
4. The seating apparatus of claim 3 wherein the wires extending
across the front of the seat are of thinner gauge than the wires in
the remainder of the seat.
5. The seating apparatus of claim 3 wherein the seat compresses 1
inch to 3 inches when sat upon by a 150-pound person.
6. The seating apparatus of claim 3 wherein the seat crowns to a
height above the ends of 1/64 to 1/16 of the seat width.
7. The seating apparatus of claim 2 wherein in each said assembly
said wires occupy a silhouette area of about 17 percent to about 75
percent of the area of their assemblies.
8. The seating apparatus of claim 2 wherein said seat arches
upwardly from front to rear and said back arches forwardly from
bottom to top.
9. The seating apparatus of claim 8 wherein said frame has a
horizontally extending member to which the rear edge of said seat
and the bottom edge of said back are both secured.
10. The seating apparatus of claim 8 wherein said frame is curved
and said assembly is attached to the frame curve and is imparted a
compound curvature.
11. The seating apparatus of claim 2 wherein the seat arches
downwardly.
12. The seating apparatus of claim 1 wherein some of the wires are
of different vibration frequency from other wires.
13. The seating apparatus of claim 12 wherein some wires are of
different thickness from others.
14. The seating apparatus of claim 12 wherein some wires are of
different arc-cycle length from others.
15. The seating apparatus of claim 12 wherein some wires are of
different temper from others.
16. The seating apparatus of claim 1 wherein the wire diameter lies
in the range of 0.05 inch to 0.15 inch.
17. The seating apparatus of claim 1 wherein the coating thickness
is from about 20 percent to about 100 percent of the wire
thickness.
18. The seating apparatus of claim 1 wherein the empty space
between the coated wires occupies between 2 percent and 75 percent
of the area of said assembly (b).
19. A chair or the like comprising
a rigid frame with two spaced-apart frame members, and
an assembly useful as a seating or back member, said assembly
comprising
a rim defining a closed area of a cylindrical surface, arched in
one direction and straight in another direction normal to said
arched direction, and having springy flexing action along said
arched direction,
a series of sinuous spring wires each positively anchored at
opposite ends to said rim and extending across said rim in a
generally circular arc parallel to the arching of said rim, the
longitudinal axes of said wires being parallel to each other, each
said wire very closely approaching its adjacent said wires at least
once each cycle,
a thin sleevelike plastic coating surrounding each said wire and
following its sinuous shape and bridging two wires wherever they
closely approach each other and also surrounding said rim, linking
said wires together and to said rim in a unitary assembly shaped as
a cylindrical arc having a curvature of less radius than that
desired in said seat or back, and
means for mounting said rim on said frame members, and for
flattening said springs somewhat to place the spring wires in
tension along a flatter cylindrical arc.
20. The chair or the like of claim 19 wherein there are two said
assemblies, one for a seat and one for a back, both mounted on said
frame.
21. The chair or the like of claim 20 wherein the arc of said seat
arches upwardly from side to side of said frame and said back
arches rearwardly from side to side to said frame.
22. The seating apparatus of claim 21 wherein the wires in the seat
lying closest to the forward edge of the chair are of lighter gauge
than the remaining wires of the seat.
23. The chair or the like of claim 20 wherein said seat arches
upwardly from front to rear and said back arches forwardly from
bottom to top.
24. The chair or the like of claim 23 wherein said seat and back
are covered with upholstery.
25. The chair or the like of claim 23 wherein the forward end of
said assembly has a sharp bend, so that said assembly extends
forward of the frame member to which that end is secured.
26. The chair or the like of claim 25 having a double bend, with
the second bend lying rear of the frame member to which that end is
secured.
27. The chair or the like of claim 23 wherein a single frame member
is secured both to the rear edge of said seat and to the lower edge
of said back.
28. The seating apparatus of claim 20 wherein said frame is curved
to impart compound curves to both said seat and said back.
29. The chair or the like of claim 19 wherein one surface of said
assembly is completely covered with a pad.
30. The chair or the like of claim 19 wherein the thicknesses of
the seat and back areas are no less than 1/200 and no more than
1/50 the height of the seat level.
Description
BACKGROUND OF THE INVENTION
This invention relates to an assembly for seats and backs, usable
in chairs, sofas, stools, benches, automobile and other
transportation seating, and the like. The seat and back units are
sub-assemblies applicable to any of various types of frames to
provide seating assemblies embodying the invention.
A hard seat can, at best, only approximate a comfortable shape,
since human posteriors vary greatly. While seats theoreti-cally
might be tailor-made for each individual, this would be costly and
would require carrying seats to whereever they would be used. A
seat which automatically tends to shape itself to each user's
posterior is a better solution to the problem. A seat with proper
resilience in the right places is thus an object of this
invention.
The seated human body rests mainly on the ischial tuberosities, the
two lower points of the pelvis. Additionally it rests on the meaty
and fatty flesh in a 1 inch to 2 inches radius therefrom. The
reason why a flat, hard surface becomes uncomfortable quickly is
that the load is concentrated on the small area of the ischial
tuberosities, and the flesh immediately covering them is compressed
with great force. Spreading this load over a larger area makes a
more comfortable condition as the unit area compressive force is
substantially reduced. Automatically shaping the seat surface to
generally conform to the sitter helps to accomplish this. On the
other hand, spreading this area over too wide a surface, such as is
the case when a seat is too soft, results in engulfing the sitter
too deeply and also often results in a lack of security, which
comes from feeling insufficiently supported. One often sees
automobiles in which the owner has gone to the trouble of
installing wooden slat accessory pads to make the seat firmer.
Dr. Bengt Akerblom, eminent Swedish authority on human posture,
says in his book Standing And Sitting Posture, published by A. B.
Nordiska Bokhandeln, 1948,
"Naturally a rather soft seat would distribute the pressure over
the tuberosities better than a hollowed rigid one. They are,
however, so small that there would be very little sense in having a
very soft and resilient seat. On the contrary, such a seat might be
expected to transfer a not inconsiderable proportion of the weight
on to tissues which are not adapted for bearing it. The best
consistency for the seat would therefore be such that although it
gave under pressure, it only gave slightly."
Proper resilience alone is not enough, either. Independent freedom
of movement of such as that found in a two-way stretchable material
more appropriately conforms to the human posterior shape, which
itself has compound curvature.
While certain spring and padding combinations can afford proper
yieldability and firmness, practically all padding materials have
the fault of being good heat insulators. In a cold room, this might
be acceptable temporarily, but people usually wear clothes
appropriate for temperature conditions anyway, and to sit for any
length of time on a heat-insulative material becomes uncomfortable
because of inhibition of dispersion of body heat in the human
posterior area. To get to a cooler spot, the person squirms. Also,
anyone who, while wearing a swim suit, has tried to sit down on the
seat of a convertible car that has been out in the hot sun, knows
that such heat conditions of the seat can be unbearable.
Some prior art seats have been made of spaced-apart wires, but in
them the spacing has been such that too much load has been
concentrated on too few wires, and this textural discomfort has
made the use of upholstery pads requisite for such seats.
An ideal seat therefore has:
1. Proper shape (including proper compound curvature).
2. Proper resilience and firmness (resilience provides shape
adaptability to each sitter).
3. Proper heat dispersion.
4. Proper surface contact area.
An object of this invention is to provide a seat more nearly
approaching the ideal than has been achieved in the past.
Each unit or sub-assembly of this invention comprises a series of
sinuous spring wires, partially held together by a thin sleevelike
plastic coating around each of the wires, bridging the wires where
they touch. In addition, however, each unit or sub-assembly of this
invention is secured together at or near the ends of the spring
wires, either by a rim or by welding them to each other or to
another member.
The invention may be considered as an improvement over my earlier
U.S. Pat. No. 2,803,293. In that patent each of the sinuous springs
had a hook on each end which partially encircled a rigid frame
member. This hooking did not positively prevent movement of the
wires relative to the frame, nor did it hold them in proper
position relative to each other prior to their being coated with
plastic. Partly because there was only line contact at best between
the wire and the frame (and unless the chair frame size was exactly
matched with the size of the hook, there would be contact at only
two points), the hook tended to rotate when subjected to force, as
when someone sat on the chair. Even after the chair had been coated
with plastic, this instability was such that when the chair was
being sat upon, the wire hooks tended to walk along the chair frame
as the sitter shifted his position, thereby distorting the seat
area, with the result of making the seat uncomfortable. The chair
of that patent was expensive to manufacture because the springs had
to be put on individually, carefully positioned, and then either
the entire chair had to be dipped, or at least the upper portion of
the chair, from the seat up, had to be dipped. Such dipping meant
that all parts of the chair that were dipped would be coated with
plastic unless something could be put on some parts of the chair to
repel the plastic. Either alternative added substantially to the
cost. Also, the coating dulled the appearance of chrome metal
furniture, and wood furniture was given a rather unpleasing
appearance. Each chair had to be made individually, and the springs
themselves had to be put on to a full chair frame individually, so
that easy handling required by mass production was not possible.
Also, great care had to be taken that the springs themselves were
not distorted by the spring manufacturer during his manufacture;
otherwise, the springs could not be properly bridged across by the
plastic.
These difficulties are overcome in the present invention, which
makes mass production quite feasible. Only the seat unit or back
unit is dipped, and assembly is relatively inexpensive, and its
manufacture is capable of automation and other mechanical aids. A
very important feature is the provision of a sub-assembly capable
of use on a wide variety of frames for different kinds and designs
of seating units. The same sub-assembly may be sold to various
manufacturers for incorporation into any of a wide variety of
frames.
Another disadvantage of my prior chair was that the chair seat and
back were substantially planar, and, even if they did have a slight
bowing, they were installed in a generally flat at-rest shape of
the spring, so that there was little spring tension or cushioning
action. In the present invention, it becomes possible to obtain
much more tension, cushioning, and resilient support from the
springs by virtue of making the unit as a cylindrical segment that
is somewhat flattened when it is put on a chair frame, rather than
making chairs from a series of substantially flat springs. The
tension of the wires pulling inwardly is one of the main forces
retaining the assembly in place.
Another important feature of the invention is the provision of a
two-way stretch, which is obtained by using plastic coatings lying
within a prescribed range of Shore durometers. The springs can
continue their flexing in the usual manner without being overly
limited by the coating, and also the spring assembly can flex and
stretch the plastic when it bridges the wires. In the prior patent,
it was possible to use a wide variety of materials, including hard
plastics such as nylon, which would certainly hold the wires
together but would not itself stretch, so that all the stretch had
to be accomplished by the wires when such a material was used. This
would give the seat some yieldability, but usually in a cylindrical
surface, rather than in the compound curve which results in a seat
that has two-way stretch. Nor was this two-way stretch recognized
or found in this type of chair until a desired range of durometers
was discovered in the present invention and used in proper
relationship to suitable gauges of wires and so enabled achievement
of this goal.
Even two-way stretchability and proper wire gauge alone have been
found to be insufficient. Resistance to bounciness is an important
property when considering the resilience necessary for a
comfortable seat and is especially necessary in transportation
seating, where up-and-down motion tends to result in harmonic
vibration, for harmonic vibrations subject the sitter to vertical
oscillations for some time after a bump has been traversed. Bounce
dampening is thus requisite, and is partly accomplished in the
present invention by proper choice of durometer of the plastic
coating. If the durometer is too low a value, the springs are too
free and are too ready to bounce. If the durometer is too high, the
seat is too stiff and lacks the proper two-way stretch quality
desired. Proper choice of durometer according to the principles of
this invention, enables the plastic to serve as a shock absorber
and provides a snubbing action against bounce.
Additionally bounce-dampening can be achieved in this invention by
employing in the assembly some wires that differ from the other
wires in gauge, shape, or spring tension or temper, so that their
harmonic vibration periods are different.
The amount of the seating area occupied by the metal thickness, and
the thickness of the plastic coating are also important features to
be considered, and little, if any, thought on these features is
evident from the prior art. For example, in the drawings for U.S.
Pat. No. 2,803,293, it can be shown that the metal occupies only
about 14 percent of the silhouette of the area, whereas I have now
found that for proper results the spring steel should occupy a
minimum of 17 percent of the silhouette of the area and,
preferably, but less important, a maximum of about 75 percent, with
the range of about 17 percent to about 25 percent generally
preferable. The coating should generally be about one-half as thick
as the wire, in order to give bridging, proper heat insulation, and
proper stretchability, but a range from about one-fifth of the wire
thickness to about equal to the wire thickness can be used. Also,
the size of the void areas between the coated wires should be no
greater than about 75 percent of the seat area used to accommodate
one adult sitter and should not be less than about 2 percent, with
about 60 percent to 75 percent being preferable.
SUMMARY OF THE INVENTION
The present invention comprises a seat or back sub-assembly which
can be secured to various frames in various manners. Basically, the
sub-assembly is a cylindrical segment, later flattened somewhat
upon installation, placing the springs in tension. Usually, but not
always, it has a rim, which usually has straight ends, typically
parallel, joined by parallel sides which are made as circular arcs.
These frames enclose a series of sinuous spring wires, each of
which is attached at its opposite ends to the rim, preferably the
end members. The wires extend between the rim ends in a circular
arc that is parallel to the circular arc of the parallel sides of
the rim. In most seats and backs each of the two extreme spring
wires is tangent at each cycle to one of the rim sides, and each
wire touches or closely approaches its adjacent sinuous spring
wires at least once per cycle.
A thin sleevelike plastic coating surrounds both the rim wires and
the sinuous spring wires, following the sinuous shape of the spring
wires and bridging between and joining them at points where they
are tangent to each other or touch each other, and also joining and
bridging between the rim and some positions of the wires. This thin
plastic coating, while leaving most of the area of the seat open in
between the wires, does link the wires and the rim together into a
unitary assembly, shaped as a cylindrical arc. When the unitary
assembly is installed on a frame as either a seat or a back, it is
flattened out somewhat but not fully. When used as a seat, the rise
between one end and the other after flattening is between a quarter
of an inch and an inch, preferably. For the back, the curvature may
be somewhat greater, preferably a radius of seven to eleven inches.
The plastic preferably is in the range of Shore A durometers
between 45 and 90, and seems to be best at about 75, so that the
two-way stretch action previously referred to is attained.
In some forms of the invention other shapes of rims are used, and
in still other forms, no rim as such is necessary, being replaced
by a special welded sub-assembly.
Note that in this invention the wires cannot go straight across.
They must undulate in order to be stretchable. Moreover, they must
be connected to each other by stretchable means. This contrasts
with my earlier patent which may allow flexible joints but does not
require stretchable joints. A 150 pound person sitting normally on
a chair of the present invention will depress it by at least 1 inch
(or at least 1/18 part of seat height) and, at most about 3 inches
(about 1/6 part of seat height). As stated, the junctures are
stretchable and flexible, but they are also so tough that they
cannot be pulled apart under usual human sitting conditions. Putty
and kneaded erasers have a rubbery quality, but not the elasticity,
stretchability, flexibility or resilience requisite. To get the
best results in this invention, the area of the silhouette of the
wires prior to coating should be at least 17 percent of the seat
area, especially of a typical area. For sufficient bridging, heat
insulation, and surface cushioning, the coating should be at least
20 percent of the wire diameter. If the seat were made from springs
alone, the comfort would be insufficient, particularly when used in
moving vehicles. It would be too bouncy. Proper durometer and
proper thickness of the coating relative to the wire thickness help
to prevent this bounciness. The reason is similar to the reason why
a car is not comfortable with metal springs alone; it also needs
the rubber, air, and hydraulic fluid in the combination of
rubber-pneumatic tires and hydraulic shock absorbers, before it can
be comfortable.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a view in perspective of a chair embodying the principles
of the invention.
FIG. 2 is a view in perspective on an enlarged scale of a seat or
back unit or sub-assembly embodying the principles of the
invention, shown before being installed on the chair frame of FIG.
1.
FIG. 3 is a view in section taken along the line 3--3 in FIG.
1.
FIG. 4 is a view in perspective of the fastener used in FIGS. 1 and
3 to secure the sub-assembly of FIG.2 to the chair frame in FIG.
1.
FIG. 5 is a diagrammatic view in end elevation showing the
difference in radii of the cylindrical assembly of FIG. 2 and the
installed seat of FIG. 1, which has been somewhat flattened out,
thereby placing the spring wires under tension.
FIG. 6 is a fragmentary enlarged view in perspective of a corner
portion of the assembly of FIG. 2, somewhat flattened out. Some
portions are broken away to show other portions that would
otherwise be obscured.
FIG. 7 is a further enlarged view in section taken along the line
7--7 in FIG. 6.
FIG. 8 is a view in section taken along the line 8--8 in FIGS. 6
and 7.
FIG. 9 is a view in section taken along the line 9--9 in FIG.
7.
FIG. 10 is a view like FIG. 7 showing how the springs may be
installed from the opposite direction in the same rim unit.
FIG. 11 is a fragmentary bottom plan view of a portion of a
modified assembly of the general type of FIG. 2, with some portions
broken away.
FIG. 12 is a view in section taken along the line 12--12 in FIG.
11.
FIG. 13 is a view in section taken along the line 13--13 in FIG.
11.
FIG. 14 is a fragmentary bottom plan view in section similar to
FIG. 11 of a modified form of rim member.
FIG. 15 is a view in section taken along the line 15--15 in FIG.
14.
FIG. 16 is a fragmentary view in perspective of a chair frame.
FIG. 17 is a further enlarged view in section taken along the line
17--17 in FIG. 16, omitting the chair frame.
FIG. 18 is a further enlarged view in section taken along the line
18--18 in FIG. 16.
FIG. 19 is a view similar to FIG. 18 showing installation of the
same unit assembly on a modified form of chair frame.
FIG. 20 is another view similar to FIG. 18 showing installation of
the same unit assembly on another modified form of chair frame.
FIG. 21 is a fragmentary view in perspective and partly in section
of another modified form of unit assembly.
FIG. 22 is a view in section taken along the line 22--22 in FIG.
21.
FIG. 23 is a view in section similar to FIG. 22 showing the same
parts at an early stage of assembly.
FIG. 24 is another similar view showing a stage of assembly
intermediate between FIGS. 22 and 23.
FIG. 25 is a fragmentary view in perspective of another form of
unit assembly.
FIG. 26 is a view in section taken along the line 26--26 in FIG.
25.
FIG. 27 is a similar view in section of the unit of FIG. 25
fastened to a chair frame.
FIG. 28 is a view in perspective of a modified form of unit
assembly having a round rim and shown flattened to the position it
assumes when fastened to a chair frame.
FIG. 29 is a view in perspective of yet another modified form of
unit assembly, wherein the rim is eliminated and the springs
secured together by a series of welds, the parts being flattened to
the arc they assume when secured to a chair frame.
FIG. 30 is a fragmentary view in perspective of a portion of a
further modified form of unit assembly.
FIG. 31 is a view like FIG. 30 of an additional modified form of
unit assembly.
FIG. 32 is a view in perspective of a modified form of chair
embodying the principles of the invention.
FIG. 33 is an end view of the unit assembly for the seat of a chair
like that of FIG. 32.
FIG. 34 is a view in side elevation of another modified form of
chair embodying the principles of the invention.
FIG. 35 is an end view of the unit assembly for the seat of a chair
like that of FIG. 34.
FIG. 36 is a fragmentary view in section showing how the seat
assembly and back assembly are both fastened to a single frame
member in the chairs of FIGS. 32 and 34.
FIG. 37 is a view in perspective of a modified form of chair
embodying the principles of the invention, wherein the seat and
back assembly are so mounted to a frame as to provide compound
curved surfaces.
FIG. 38 is a view in side elevation of the chair of FIG. 37.
FIG. 39 is an enlarged top plan diagrammatic view in two halves
illustrating the two-way stretch effect of the wires and plastic
assembly.
FIG. 40 is a view in side elevation of an opened folding chair
embodying the principles of the invention.
FIG. 41 is a view in side elevation of the folding chair of FIG. 40
in folded position.
FIG. 42 is a diagrammatic view of the relative arcs and radii of
back and seat for the chair of FIG. 40.
FIGS. 43 to 51 are all top plan fragmentary views of various
patterns of the arcuate sinuous members, in each instance with
portions of the wire shown uncovered and with plastic linking the
spring members together. Various patterns are shown as illustrative
of the many, many more that are possible in this invention.
FIG. 52 is a view in front elevation of the lower portion of a
modified form of chair embodying the principles of the
invention.
FIG. 53 is a view in side elevation of a stool embodying the
principles of the invention in another modified form.
DESCRIPTION OF SOME PREFERRED EMBODIMENTS
An Example of a Chair Embodying the Invention (FIG. 1)
Many, many types of seating units may embody the principles of this
invention, including chairs, sofas, davenports, benches, stools,
automobile seats, bus seats, camp chairs, and so on.
A chair 60 is shown in FIG. 1 for the purpose of giving one example
of a type of seating unit that can embody the principles of the
invention. This example is not to be construed as representing all
types of seating units or even all types of the chairs, which can
vary greatly in frame structure, appearance, and so on. The basic
part of this invention is concerned with the seating and back unit
more than with the framework of the chair itself.
The chair 60 has front legs 61, 62 and rear legs 63 and 64 which
continue up, preferably at an angle, to form back frame portions or
members 65 and 66. The number of pieces used in making the chair
frame is immaterial to this invention, and whether the frame is
continuous or pieces are welded or otherwise secured together does
not matter, so far as the present invention is concerned.
Horizontal side frame portions or members 67 and 68 join the front
legs 61 and 62 to the rear legs 63, 64 where they meet the back
frame members 65 and 66. The use of bracing and top members is not
significant in the present invention, though some such members are
shown in the drawing, and there must be some rigid means for
holding the frame members 67 and 68 apart and for holding the frame
members 65 and 66 apart. In this particular form of the invention
the back frame members 65 and 66 are rigidly held parallel to each
other and the side frame members 67 and 68 are rigidly held
parallel to each other. This parallelism need not always be
present, but it is preferred.
A seat unit 70 is supported by the side frame members 67 and 68 and
a back unit 70A is supported by the frame members 65 and 66. The
seat unit 70 and the back unit 70A are very similar to each other;
they may in some instances be identical, but usually the back unit
70A is somewhat smaller than the seat unit 70 and is usually made
from a smaller gauge of wire.
The structure of the units 70 and 70A is highly important in this
invention. So is the attachment of the units 70 and 70A to a chair
frame.
The Seat Unit 70 (FIG. 2)
FIG. 2 shows the seat unit 70 before it is incorporated into the
chair; the view also represents basically what the unit 70A looks
like, although the unit 70A may be different in size or even in
structure or appearance, where desired.
In this example the unit 70 comprises a rim 71 having spaced-apart
straight ends 72 and 73 joined by parallel side members 74 and 75,
which are shaped as circular arcs. Lest there be some confusion in
the mind of the reader, it is pointed out that the straight end
members 72 and 73 are secured to the side frame members 67 and 68
of the chair, and thus extend from front to rear at each side of
the chair 60, while the side members 74 and 75 become the front and
back edges of the seat in the assembled chair 60. However, so far
as the seat unit 70 itself is concerned, the members 72 and 73 are
the ends and the side members 74 and 75 are arcuate or circular
sides.
Extending from end to end across the two end members 72 and 73 is a
plurality of sinuous spring wires 76, 76a, 76b. . . 76n, which are
naturally arched into a circular arc of the same size and shape as
that of the side members 74 and 75. These springs 76, 76a, etc.,
may have many shapes, some of which are shown in FIGS. 43 to 51.
They may be of the type often called non-sagging springs and
sometimes sold under the trademark No-Sag. Typical wires 76, etc.,
of this type are of spring steel, having 0.60 percent to 0.75
percent carbon and 0.90 percent to 1.20 percent manganese. Tensile
strength typically runs about 215,000 to 265,000 p.s.i., and their
Rockwell hardness is about 39-41 RC range. The diameter of the
wires 76, etc., preferably lies in the range of 0.05 inch to 0.15
inch. Too thick a wire tends to concentrate the stiffness too much
and the seat is too firm, while too thin a wire makes the seat too
soft.
Each end 77, 78 of each spring 76 (see FIGS. 6-15) is firmly
anchored to and secured to one of the end members 72, 73 of the rim
71. Various means are employed to achieve this firm anchorage, and
some of these are described below in following sections. They
include friction grips and welding, among the many types of
mechanical connections.
The spring members 76, 76a, 76b,. . . . .76n are placed tangent to
each other, each of the two extreme spring wires 76 and 76n being
substantially tangent at each cycle to one of the side members 74
and 75. Each wire 76 touches its adjacent wires at least once per
cycle. The touching may be actual contact or it may be approximate
touching or close approach, because, as will be seen, the assembly
70 is held together in a way that does not require actual physical
contact of the metal at each tangent point, but it is always a very
close relationship if not an actual touching.
A thin sleevelike plastic coating 79 surrounds the spring wires 76,
follows their sinuous shape, and bridges the wires 76, 76a, etc.,
where they substantially touch each other. Preferably, the plastic
coating 79 is about one-half of the wire thickness, or in the range
of about one-fifth of the wire thickness to about equal to the wire
thickness. At the junctures, the thickness may be mostly greater,
though the wires themselves may touch each other. This plastic
coating 79 also surrounds the rim 71 and links the wires 76 and the
end and side members of the rim 71 together into the unitary
assembly 70. The plastic coating 79 holds the wires 76 to each
other as they span between the rim ends 72 and 73, and it holds the
side wires 74 and 75 to the extreme springs 76 and 76n at each
point of tangency. The result is the arcuate or cylindrical arc
shape, typically like that shown in FIG. 2, although the arc may be
somewhat flatter or somewhat rounder.
Thus, the complete assembly 70 is a unit which can be sold or
shipped as a unit and can be assembled to the chair 60 of FIG. 1 or
to many other kinds of chairs, so long as the proper size and shape
is accommodated for in one way or another, that is, either by the
chair itself being shaped to go with the seat unit 70 or the seat
unit 70 itself made so that it will go with a chair frame or other
type of seating unit frame. The unit 70 by itself is capable of
mass production, and is easily assembled into a chair or other
seating unit by securing the two end members 72 and 73 to a
suitable rigid frame.
An Independent Type of Securing Means (FIGS. 3 and 4)
Various securing means are discussed in this specification, some of
them being shown for example in FIGS. 16 through 20, and in FIGS.
26 and 27, among others. Basically, the securing means may be an
integral part of the unit 70, or may be an integral part of the
chair frame or other frame to which the unit 70 is to be secured,
or it may be an independent member not an integral part of either
of these. An example of the last-mentioned type in the securing
member 80 shown in FIGS. 3 and 4. This may be a suitable metal or
plastic member having a generally tubular rim-receiving portion 81,
with an opening 82 therethrough that fits snugly around a rim
member 72 or 73. The member 80 has a pair of flanges 83, 84 having
an opening 85 through them. As shown in FIG. 3, the chair frame
member 67 may have a series of openings 86 adapted to receive the
rwo wings 83 and 84, after the member 80 has been fastened around
the rim member 72 or 73. Then a suitable screw 87 may be inserted
through a suitable opening 88 of the frame member 67 and secured by
means of the openings 85 to the wings 83 and 84. As shown in FIG.
1, there may be several of these units 80 to secure the seat unit
70 and the back unit 70A to the chair 60.
From this it will be apparent that the assembly 70 and the assembly
70A may be made as units by one manufacturer and sold to another
manufacturer who makes the chair frames. So long as the
dimensioning is correct, the two manufacturers need not know
precisely what each other is doing, for the unit 70, if made in the
correct dimensions, can be secured to a variety of different types
of chair frames, -- or to other frames of seating members, for that
matter, including benches, automobile frames, and so on. The unit
70 enables the chair manufacturer to secure the seat or back in
place in the most attractive and pleasing and most practical
way.
As will be seen from later portions of the specification, there are
many, many ways in which the fastening of the member 70 to the
chair 60 can be done, and this is just one example.
The Significance of Flattening the Cylindrical Arc (FIG. 5)
FIG. 5 shows diagrammatically what happens when the unit 70 of FIG.
2 is put into the chair 60 of FIG. 1. The round cylindrical arc of
FIG. 2 with radius R1 is flattened from the shape shown at the
bottom of FIG. 5 to the shape shown at the top of FIG. 5, where it
has a larger radius R2. The unit 70 then has a broader span and its
arc is somewhat flattened, so that it can be used as a seat. It has
a crown height h, shown on the drawing, and it is still a
cylindrical arc, though much flatter.
This flattening of a round assembly is an important feature of the
invention. By forming the unit 70 initially as a cylindrical arc,
which is quite round and fairly well closed, and then flattening it
considerably, a large amount of desirable tension is placed into
the completed unit 70, so that the seat has a springy feel to it,
acting substantially as though there was a large cushion instead of
simply an assembly of thin springs. The exact amount of crown
height h or of curvature depends, of course, somewhat on taste, but
generally there will be about a maximum of one inch crown height h
in a sixteen-inch wide seating unit 70, and the proportion is
usually best considered as being a crown height h of
one-sixty-fourth to one-sixteenth of the span.
The amount of force required to flatten a seat of typical dining
chair size is important as well. For purposes of the present
invention it has been found that a collection of springs in an
assembly 70, requiring a force of between 340 pounds and 680 pounds
to flatten it gives a seat proper tension, (preferably around 500
pounds). This is the force exerted in pulling the two ends 72, 73
apart to be of an appropriate distance to fit onto the chair frame
members 67, 68.
For the chair back, somewhat different rules apply and it will be
noticed that in the chair of FIG. 1, as in most such chairs, the
arc of the back extends rearwardly and is not something that the
sitter tends to flatten; rather, he tends to increase the arc
curvature, reducing its radius.
In both the seat and the back, the tension of the wires pulling
inwardly, which results from flattening, is also one of the main
forces retaining the wires in place.
SIGNIFICANCE OF THE PLASTIC COATING 79 (FIG. 39)
The plastic coating 79 may be chosen from various types of plastic,
such as polyvinyl chloride, polyvinyl acetate, mixtures thereof,
other vinyl compounds, polyethylene, butadiene, acrylic elastomers,
and so on. The material may be transparent, where that is desired,
or may be opaque and impart its own color to the unit. It may
contain dye or pigment which imparts a desired color, completely
preventing view of the wires 76 themselves and giving the
appearance of constituting the actual seating material. The plastic
coating 79 may be semi-transparent and may give shade or tone to
the overall color.
It will be noticed that in this invention the plastic is confined
to the unit 70 or 70A and is not applied at all to the chair frame,
so that the chair frame may have any surface or treatment that is
desired without interference from the nature of the plastic
coating.
The sinuous wires 76 are preferably not welded to each other at
their points of tangency but are held together only by the plastic
coating 79, with the wires 76 either touching each other or even
slightly apart but closely approaching each other. The same is true
of the connection between the wires 76 and the arcuate side members
74 and 75 of the rim 71.
An important feature of the plastic coating 79 is that by choosing
the proper range of durometer, a two-way stretch effect can be
obtained, as illustrated in FIG. 39. The springs 76 not only
stretch in the well known manner of non-sagging springs, but also
the plastic coating 79 between the adjacent springs 76 may be
stretched, and this two-way stretch effect gives a wide range of
resilience to the seat. If the plastic 79 is too hard, there can be
substantially no such stretch, and if the plastic 79 is too soft,
there will be too much stretch, the springs 76 themselves are not
properly availed of, and the unit 70 might even be torn apart after
short use. By holding the Shore durometer of the plastic coating
within critical values, the effect is right, with sufficient
rigidity so that the springs 76 are taken advantage of and so that
they are held apart with sufficient resilience so that the whole is
not simply encased in a rigid covering. I have found that the
durometer range necessary to achieve this critical action is from
about 45 to about 90 Shore A-scale durometer, with a preferable
value of about 75.
In FIG. 39 there are two portions. The left portion illustrates
part of a seat 70 before it is sat upon, with the springs 76
therefore in their normal configuration. A typical area 280 is
shown outlined, this area comprising one complete cycle of wires
76, so that it is representative of the total area of the seat 70
so far as the percentage of metal silhouette per total area is
concerned. This area can therefore be used for determining
accurately the silhouette of the wire and its average occupation of
the seat area. Taking the gauge or wire diameter as G, the length
of the wire can be determined in terms of G by measuring the length
of the center lines of all the wires 76 in the area 280 in terms of
G, and the value is found to be 34G. The area 280 itself measures
14.6G by 10.7G, which is 156.22G.sup.2. The silhouette area of the
wire in the area 280 is 34G.sup.2, which is 21.76 percent of the
area 280. This value lies within the required range of 17 percent
to about 75 percent of the seat area, mentioned earlier, and also
within the range of the preferred range of 17 percent to about 25
percent.
Also, the empty spaces between the coated wires should be no
greater than about 75 percent and no less than about 2 percent of
the area of the seat surface, and the range of about 60 percent to
about 75 percent is preferred. The minimum of about 2 percent
barely provides sufficient air ventilation.
The wires 76 in the seat 70 lie closely adjacent each other and
nearly touch at points of near-tangency, where the distance D1
between them, as shown in FIG. 39, may be as low as zero, and where
the overall distance from the outside to the outside is T1. The
plastic coating 79 forms a bridge fastening the wires 76 together
at 281 and has a thickness t.
The right portion of FIG. 39 illustrates what happens when the seat
70 is stretched, as when it is sat upon. The length L1 in the left
portion extends to the longer length L2 in the right portion. The
width W1 in the left portion extends also to become the width W2 in
the right portion. The distance D1 in the left portion has
stretched to become the distance D2 in the right portion, and the
distance T1 has stretched to become the distance T2. Thus is seen
the importance of the bridge or juncture 281 and of the
stretchability of the plastic 79 at this bridge or juncture 281.
This, of course, is related also to the thickness t of the plastic
coating 79.
A glance at the seat 70 might lead one to conclude that the surface
configuration would be texturally uncomfortable. However, this
conclusion would be mistaken, for the seat 70 acts differently than
one might at first conclude, for the following reasons:
1. The average occupation by the wire of the typical area (i.e. 17
percent to 75 percent) is so great that the human posterior is
supported without concentrating the load too much. In contrast, if
the wire occupies less than about 17 percent of the area (e.g., the
14.4 percent occupation of the FIG. 2 area in U. S. Pat. No.
2,803,293), the seat would be texturally uncomfortable.
2. The empty spaces constitute at least 2 percent of the seat area,
in order to give sufficient air ventilation, and preferably occupy
much more of the seat area, up to about 75 percent.
3. The wire 76 is not exposed bare metal, which would be highly
heat conductive and therefore unpleasant and uncomfortable. The
wire 76 is adequately coated with plastic 79 which is low in heat
conductivity; so it is pleasant and comfortable to sit upon.
4. The coating 79 lies within the range of Shore A durometers
(45-90) where it is neither too hard nor too soft; in fact it tends
in itself to provide some cushioning effect, and its action at the
bridges 281 adds to the comfort. Without this, the seat 70 could be
too hard or too soft.
5. The two-way stretch discussed above provides automatic
contouring, offering minimal resistance to the human posterior.
Without this two-way stretch, the seat 70 might become increasingly
uncomfortable.
Friction Fastening of the Wires to the Rim (FIGS. 6-10)
While many means of fastening the spring 76 to the rim 71 may be
employed, some are naturally preferred above others. The preference
depends on many factors, such as manufacturers' capabilities and
preferments, specifications given by customers, and various
features of cost and capital equipment required.
One desirable type of fastening employs a friction lock principle,
shown in FIGS. 6 to 10. In this form, the rim 71 has end members 72
and 73 that are generally tubular; they may be made as a solid
tube, but preferably, as shown in the drawings, each member 72 or
73 is an open tube that may be made by curling a narrow strip of
metal in a generally circular shape. As shown, the member 72 or 73
has a flat bottom portion 90 which is punched through at intervals
to provide openings 91 and wings 92 and 93, extending at an angle
such as about 30.degree.. Machines for making these on either a
batch basis or on a substantially continuous basis are readily
devised, so that the members 72 and 73 may be made as long strips
cut into desired lengths.
As will be seen by comparing FIGS. 7 and 10, the member 73 may be
considered as being the same as the member 72, so that they are
reversible; in other words, the same piece may be used in either
direction and at either end of the rim. Of course, bending in one
direction in reversal is a possibility, but no such reversal or
sense of direction is required when the wings 92 and 93 are made as
shown.
A series of side openings or slots 94 provide an entryway for the
wire end 77 or 78. The wire end 77 or 78 is inserted in the opening
94 and then moved lengthwise of the member 72 or 73 until it is
stopped by engaging one of the wings 92 or 93. When inserted, the
wire 76 depresses the wing 92 (or 93) under pressure, but when it
engages the end of the far wing 93 (or 92), it can progress no
further. Thus, accurate positioning is assured, and this can be
made to provide automatically the desired tangencies of the wires
76 with each other and with the side members 74 and 75 of the rim
71. Once inserted, the wire end 77 or 78 cannot be retracted,
because on retraction, the depressed wing 92 (or 93) digs into the
wire 76 and prevents outward movement. The invention is to prevent
any relative movement between the wire end 77 or 78 and the member
72 or 73 after assembly. The wire 76 can move across a depressed
wing 92 in the direction toward a stop wing 93 but cannot move back
against the wing 92, once it has been moved in. As shown in FIGS. 7
and 10, the movement can be in either direction with the same
effect exactly; it may be, of course, in opposite directions at
opposite ends of the rim 71. Thus, the wires 76 are locked into the
complete assembly by friction in this form of the invention. The
plastic coating 79 is applied after this assembly is completed.
Resistance Weld Securement of the Rim and Spring Wires (FIGS. 11 to
13)
FIGS. 11 through 13 show the use of a rim end member 95 with an
inverted channel or U shape and having resistance weld protrusions
96 against which the wire ends 77 or 78 are moved. An entrance
opening 97 for the wire 76 is provided. Various stop means may be
employed, or the stop may simply be provided by the machine which
inserts the spring wire 76 through the opening 97 into the inverted
channel member 95. In any event, the spring wire end 77, once
inserted, is held in position temporarily while the resistance weld
is made, so that the protrusion 96 in effect becomes part of the
spring wire 76 and the spring wire 76 part of the channel 95,
holding the rim and wire together as a single piece. The resistance
welds may be made one at a time or may be made for a whole end
member 95 at once, or for both ends at once. In this form of the
invention, then, the assembly 70 is held together, not only by the
plastic coating 79, but also by being welded at its ends. The
plastic coating 79 is, of course, applied after the welding.
A Snap Fastening (FIGS. 14 and 15)
In the structure shown in FIGS. 14 and 15, a snap-in type of
friction holding is employed. In this instance a rim member 100 has
a spring-like structure, being shaped as a channel with springy
lips 101 and 102 that lie closer together than the thickness of the
wires 76. While typically metal, the member 100 may be made from
plastic. The lips 101 and 102 are spread apart when the spring wire
76 is inserted from the lower end, with the aid of a side slot 103.
Once inserted, the wire end 77 is snapped into place and cannot be
retracted, but is held by the rim lips 101 and 102. Stops may be
provided by slight punchings or dimples that limit the course of
the wire end 77, or this may be completely unnecessary due to the
use of holes or openings 103 which prevent more than limited
movement of the wire 76, being just large enough to allow insertion
of the spring wire end 77 into the rim 100. The assembly is again
dipped in plastic 79 after this.
Another Friction Lock and Securement of the Unit to a Chair Frame
(FIGS. 16-20)
FIG. 16 shows how a tubular rim end member 105 of metal or plastic
is formed to provide a series of holes 106 to receive the ends 77
or 78 of each spring wire 76. Approximately opposite and
longitudinally apart from the holes 106 the tube 105 is formed to
provide wings 107 while providing stops 108, limiting movement of
the spring wire ends 77 within the tubular member 105. The tube
interior 109 may fit snugly around the wire end 77, and there may
be no other friction retention means other than this. FIG. 17 shows
that the tube 105 makes a smooth friction fit with a wire end 77 so
that the wire end 77 is held by friction against going back and
forth and engages the end 108 of the succeeding wing 107 to prevent
further movement and to act as a stop. The plastic coating 79 helps
to prevent relative movement between the tube 105 and wire 76.
There may be some additional means, such as welding if desired.
The tubular end member 105 of FIG. 16 is also shown as having
depending ears 110 with an opening 111 through which suitable
screws 112 or bolts or rivets may pass to secure the unit 70 to the
chair frame member 65, 66, 67, or 68. For example, as shown in
FIGS. 16 and 18, a screw 112 may simply pass through the ear 110
into an opening 113 in a tubular metal frame member 67.
FIG. 19 shows another way in which the same rim member 105 can be
used. In this case, a tubular metal chair frame member 114 has been
provided with top openings 115 to receive the complete ear 110, and
a screw 112 is put in from the side of that member 114, passing
through an opening 116 and the opening 111 in the wing 110 and
holding it there.
A similar way is shown in FIG. 20 of employing the same rim member
105 with a wooden chair frame member 117 with the screw 112 passing
through the wood into the opening 111. Various other means of
securement may, of course, be used.
A Flattened Type of Rim With a Friction Lock (FIGS. 21-24)
Another way of securing the spring wires 76 to the rim 72 is shown
in FIGS. 21 through 24. Here is shown a flattened channel rim end
member 120 of metal or plastic, with an upper flat portion 121 and
a lower flat portion 122. The wire end 78 is held in position by
friction by a wing 123 partly punched out and bent up from the
lower portion 122. The wire end 78 is also held against a stop 124
in the rim end member 120. Thus, the friction holding wing 123 and
the stop 124 are both provided by a series of partly punched
bent-out members having the stop portion 124 of greater depth than
the wing 123. The action is shown in FIGS. 22 through 24, FIG. 22
representing the final position, in which the wire end 78 is passed
over the retaining wing 123 and cannot go back. FIG. 23 shows first
the insertion, and FIG. 24 shows the pressing and flattening of the
wing member 123 during the passage over it, leading to the locking
action of FIG. 22.
FIG. 21 also shows a modified form of rim side member 125. The rim
member 125 is not straight like the side members 74 and 75, but is
itself an arcuate sinuous member. In this instance, it has a
different form from that of the wires 76 and is substantially a
sine curve which fills in a major portion of the recess in the wire
76 that otherwise would exist unfilled; therefore, although sinuous
in form, the rim member 125 does not leave the large projections
exposed which would be exposed if the member 125 were not there.
Instead, the projections exposed are relatively short and do not
tend to catch on clothing. The whole is again coated with the
plastic 79.
FIG. 21 also shows a sinuous wire 126 that is different in length
and shape from the other wires 76. The function of the wire 126 is
to introduces a member with vibration characteristics different
from those of the wires 76, 76a etc. The effect of this
introduction is to provide bounce dampening, a feature usually
found necessary in transportation seating. The wires 76, 76a etc.,
characteristically having one vibration frequency are attached in
the assembly to the wire 126 which has a different vibration
frequency, and thereby the assembly 70 has its bounce
characteristics strongly modified, if not totally eliminated.
Another Form of Rim and of Attachment to the Spring Members (FIGS.
25-27)
The forms which the rims may take are practically infinite. FIG. 25
shows a corner portion of a rim 130 in which one side member 131 is
continuous with a portion 132 of the end member, which may define
the complete rim end member. Another member of the same metallic
wire type is shown at 133 parallel to and spaced from the member
132, along each side member 131. The two are held together by
resistance-welding each of them at 139 to a third rim end portion
134. The rim end portion 134 has two flat portions 135 and 136
which abut the members 132 and 133, and between these it has an
open-end tubular portion 137 to receive the wire end 78 through a
series of openings 138. The members 78 are slipped through the
openings 138 and into the interior of the portion 137 and are
pushed to the stop 139. Then the composite, held together by the
springiness of the members, is dipped in the elastomer 79. After
dipping, the assembly may be slid into a hollow frame member 140
which may be an integral part of the chair or seat frame and which
has a continuous slot 141 through which the wires 76 extend. Note
that the wires 76c, etc., are larger than the wires 76a and 76b.
This enables the use of heavier wires where the main seating
pressure is and lighter wires at the forward edge where too stiff
wires can cause discomfort. It also provides bounce dampening by
putting wires of different vibration frequency adjacent to each
other in the assembly.
A Sub-Assembly of This Assembly Having a Round Frame (FIG. 28)
While the rectangular type of rim, like the rim 71, is usually the
most desirable, that is not always the case. It may be made in a
trapezoidal shape or in other shapes. As an example of which can be
done, an assembly 143 is shown in FIG. 28. The assembly 143 has a
round, that is, generally circular rim 144, which is continuous and
which is secured, as by welding, to a series of spring members 76,
etc. After the securement, the assembly is dipped in elastomer or
plastic to form the completed assembly 143. The plastic 79 again
joins the wire spring members 76 together and again helps to
enforce their attachment to the rim 144 and to surround it,
although the attachment is adequate without that. The positive
securing together is by direct welding, in this instance, of any
suitable type, whether of spot welding, projection welding, or
whatever. Although the rim 144 is circular, it should not be though
of as being a flat circle. It is again made in the same general
cylindrical shape as that in which the unit 70 is shown in FIG. 2,
but the assembly 143 has been spread out and somewhat flattened,
but not completely, in FIG. 28 to show how it looks when mounted on
a chair frame, but from this it should be gathered and should be
remembered that the entire assembly is again a cylindrical segment
of which the ends may almost meet until they are flattened.
A Rimless Assembly of the Invention (FIG. 29)
FIG. 29 shows an assembly 145 of the invention in which there is no
rim member whatever. The wire members 76, 76a, 76b, . . . 76n are
also secured together close to their ends, but in this instance,
not at them, by a series of resistance welded joints 146, 146a, . .
. 146n. This securing is only at one place along each end. This
provision of a metal weld joining together the wires, in this
instance in two places, one near each end but somewhat spaced from
it, is again a firm attachment. Since all the members 76, 76a,
etc., have the same arcuate curve, they are easily kept as a unit
in the general form as shown in FIG. 2, the illustration in FIG. 29
showing the assembly 145 flattened out as it would be in an
installed seat.
In this instance, the wires 76, 76a, 76b,. . .76n have free ends 77
and 78, which may be installed in attachment members provided in
the chair frame itself, or there may be members that will clamp
these to the chair frame, or other attachments may be used. The
assembly as a whole, after welding, is dipped in the plastic to
provide the coating 79 of the wires 76 and to provide the links
between the various wires.
It will be seen that, in this instance, the series of welds 146,
146a. . .146n plus the wires 76, 76a. . .76n in effect provides
what is substantially a rim, but it is a peculiar rim, in that it
is really made up of a series of segments of the wires 76, 76a,
etc., which are in line with each other and with the weld joints
146. But, the unit 145 is an assembly before it is installed on the
chair frame. It can be shipped as an assembly and it is held
together by a very strong metal means, as well as by the plastic
79.
An Assembly Welded to a Straight-Wire Rim (FIG. 30)
A portion of an assembly 150 is shown in FIG. 30 in which the wire
76, 76a, 76b, etc., are welded to a straight end portion 151 of a
rim 152 having side portions 153. The welds are at the locations
154, 154a, 154b, . . . . The wire ends 78 are shown here lying
outside the rim member 151, and they may be used for fastening or
they may be cut off, if that is desired, and the fastening then be
by the rim portion 151. The same cylindrical shape of the unit 150
is intended to be implied as in the previous drawings, for the
assembly 150 is again substantially a cylindrical segment which
must be flattened out when it is installed on a chair frame. The
entire assembly 150 is coated with plastic 79 after the welding has
been completed.
Another Form of Assembly with the Springs Welded to the Rim (FIG.
31)
An assembly 155 shown in FIG. 31, has a rim 156 with an end portion
157 and side portion 158 shown. The rim 156 may be continuous. The
portion 157 is provided with a series of projecting portions 158 to
which wire ends 78 are welded at junctures 159 by any suitable
welding means. The rim 151 comprises a welded structure, and after
welding the whole is again coated with the plastic 79.
A Modified Form of Chair (FIGS. 32 and 33)
FIG. 32 shows a chair 160 incorporating a seat assembly 161 and a
back assembly 162. The back assembly 162 is substantially like the
assembly 70A, with two exceptions. In the first place, the frame
members 163 and 164 to which it is secured, extend horizontally
rather than being vertical; the second exception is that the
assembly 162 has end rim members 165 and 166, and these, of course,
extend horizontally so that they can be secured to the frame
members 163 and 164, but, in this particular instance, by way of
example, there are no side rim members corresponding to the members
74 and 75 of the assembly 70 in FIG. 2. Instead, the wires 76 are
free at each side. Since they are at the sides of the chair, they
are less likely to catch on clothing, and they may be left in their
natural state. Also, the intention here is to cover them with
fabric 167, so that they are not truly exposed and do not present
even that apparent hazard.
The seat member 161 is basically like the member 162 for the back,
but has an important difference. The similarities are that the
wires are free at each side, that the seat is covered with fabric,
and that it has end members 170 and 171 which are secured to chair
frame members 168 and 164. The difference is that a bend 172 is
provided, which is a sharp bend spaced from but relatively near the
rim member 171. This bend 172 functions (1) to give the chair in
its fore-and-aft seating pattern, which obviously differs from the
side-to-side pattern of the chair shown in FIG. 1, a resiliency at
the front which is extremely desirable, and (2) also an accentuated
curve at the front end which makes the chair more comfortable than
it would be if this were absent.
Another Fore-and-Aft Chair Seat Arrangement (FIGS. 34-36)
A chair 175 is shown in FIG. 34 having a seat assembly 176 and a
back assembly 162, like that of the chair 160. The difference
between the seat assembly 176 and the seat assembly 161 is that the
seat unit 176 has what is sometimes called a "fishmouth"
construction with two bends 177 and 178 adjacent a forward edge
179. The rear end rim member 170 is the same as in the chair 160.
The fishmouth structure gives additional springiness and comfort
and is considered desirable by some manufacturers.
FIG. 36 shows how the rim members 170 and 166 can be secured to the
single horizontal frame member 164, with the aid of a clip 180
which receives both of these members and has a pair of ears 181 and
182 that are secured to the frame member 164 by a screw 183
extending through an opening 184 in the frame member 164 and
through an opening 185 in the ears 181 and 182, approximately at
right angles to the screw 183. The attachment is similar to that
already shown in a previous drawing, except that here both the seat
176 and the back 162 are simultaneously attached. It will be noted
also that in this instance, the back member 162 is arched forwardly
rather than rearwardly, this being because of the use of the two
parallel suspensions, both being horizontal instead of
vertical.
A Chair With A Compound Curve (FIGS. 37 and 38)
A chair 190 is shown in FIGS. 37 and 38. This chair makes use of
the same assemblies 70 and 70A already discussed for the seat and
the back. The difference in this chair is that the frame is so
constructed that a compound curve is formed in the back and in the
seat. Thus, the front legs 191 and 192 merge into side frame
members 193 and 194 by relatively wide radius curve portions 195
and 196, and the rear frame members 197 and 198 also have upper
portions 199 and 199a that are curved. The result is, that when the
seat assembly 70 is installed, it has a front portion which is
curved in the direction of the chair frame, while at the same time
it is arched across between the frame members 193 and 194, and the
same is true of the back member. The compound curves give added
comfort through more appropriate contouring. Straight portions at
the front edge of a chair are likely to cut into the legs and to be
uncomfortable, and a curved portion eases that part and eliminates
the sharp cutoff, insofar as the sitter is concerned.
A Folding Chair Embodying the Principles of the Invention (FIGS.
40-42)
A folding chair 200 is shown in FIGS. 40 and 41, having a seat 201
and a back 202, which may be made from units 70 and 70A embodying
the principles of the invention. The folding chair 200 has a pair
of side frame members 203 that support the seat 201, a pair of rear
leg members 204 extending to the front of the chair 200, and a pair
of front leg and back frame members 205 that support the back
202.
FIGS. 40 to 42 show a significant feature of the invention. The
seat 201 is crowned upwardly and the back 202 is crowned
rearwardly, so that when the chair 200 is folded, the seat 201 can
nest within the back 202 as shown in FIG. 41. This enables very
compact folding of the chair 200, so that the thickness of the
chair 200 in a stack of such folding chairs need be no greater than
the frame thickness.
This feature of compact stackability is also applicable in a
non-folding but compactly stackable chair (Cf. U.S. Pat. Re. No.
26,071) wherein seats nest compactly over seats, and backs nest
compactly into backs.
Some of the features of the folding chair part are illustrated also
in the diagrammatic view of FIG. 42. This shows that the seat 201
may be curved less than the back 202, and in most examples this
provides a more comfortable chair 200 than if they were curved only
to fit each other. The back concavity should be equal to or greater
than that of the seat; in other words the radius of curvature of
the seat 201 is greater than the radius of curvature of the back
202. The back 202 may vary from having a radius identical to that
of the seat 201, to a radius no less than half of the radius of the
seat 201, in order to secure both comfort and adequate folding. Of
course when the curvatures are different, the stacking may be
somewhat less compact, but this is a disadvantage to be weighed
against the other disadvantage of having the seat and back be
uncomfortable when sat upon. In FIG. 42 is illustrated another
unique feature of the invention. The seat member 201 has a crown
height of between 1/4 inch and 1 inch. When the seat 201 is folded
into the back 202, its under side 206 -- as well as its upper
surface 207 -- fits within the chord 208 of the back 202.
Preferably, the back 202 should have a radius of curvature R3 less
than the radius of curvature R4 of the seat crown 201. The
preferred radius R3 is between 11 and 15 inches, and preferred R4
is 33 to 88 inches for a 17-inch span.
Some of the Many Patterns of Wire Possible in This Invention (FIGS.
43 to 51)
A substantially infinite number of wire patterns is possible under
this invention. The one shown heretofore with the wire 76 is a very
good pattern but it is not the only good one that can be used.
Patterns can be used for their structural features, because of
manufacturing convenience, or because of design features. Some of
these features will appear from the selected forms shown, and in
all of them it will be seen that the wires, whether in parallel
pattern or alternate patterns, touch each other at least once per
cycle; the touching may be flush to each other in the same plane,
or may be by an overlap of planes with the unit still having
substantially the same plane.
FIG. 43 shows a wire 211 with vinyl covering 212 and an adjacent
wire 213 with vinyl covering 212 also on it. The wires 211 and 213
are bent in the same pattern but are set to alternate, so that one
is rotated 180.degree. relative to the other; instead of each wire
211 being strictly parallel to its adjacent wire 213, their
sinuosities are reversed, and the alternating effect is obtained.
Alternation can give some interesting designs, such as the one
shown here. The length of the one cycle has been marked on the
drawing, and it will be seen that the cycle is rather long, partly
due to the alternation and partly due to the wire pattern itself.
Thus, the wire 211, starting from the left-hand end, has a long
vertical portion 214, then a horizontal portion 215 succeeded by a
short vertical portion 216, then a horizontal portion 217
preferably the same length as the portion 215. The portion 217 is
followed by a portion 218 identical in length to the portion 216
and then leading to another portion 219 which is parallel to and in
line with the portion 215 and is again of the same length. The
portion 219 is followed by a portion 220 that is longer than the
portions 216 and 218 and equal in length to the portion 214,
therefore raising the wire 211 up to a new level. This is succeeded
by a horizontal portion 221 of the same length as the portion 215
and parallel to it but displaced from it. This in turn is succeeded
by a short portion 222 the same length as the portion 218 but
starting from a different place, so that the succeeding portion 223
is not in line with the portions 215 and 219. Another portion 224
equal in length to the portion 222 is followed by a portion 225 in
line with and equal in length to the portion 221, and this is
followed in turn by a portion 214a identical to the portion 214 and
beginning a new cycle.
The wire 213 adjacent to the wire 211 has the same pattern but is
reversed, so that the wires 211 and 213 touch at the portions 215
and 219. The wires 211 and 213 touch the other wires to which they
are adjacent at the portions 221 and 225. These touching portions
in this instance extend for the whole width, and the plastic
coating 212 covers these portions as well as the individual
wires.
FIG. 44 shows a wire 230 having a sinuous shape and and adjacent
identical wire 231 both of them being covered by a plastic 232. The
length of one cycle is in this instance much shorter. The wire 230
has a flaring portion that describes what are nearly two circles
233 and 234, with the radii displaced, and these near-circles 233
and 234 are joined by a smooth connecting curve 235. Again the
pattern is interesting, and the structural effects substantially
the same as what have already been described.
FIG. 45 shows a wire 240 which is made in a sinuous pattern not
unlike the wire 76. The adjacent wires are overlapped so that the
wire 240 lies over a wire 241 and beneath a wire 242, and the
plastic covering 243 joins all the wires. This pattern provides a
small opening 244 through the overlaps and a large opening 245.
This makes an interesting pattern, is another way of forming the
assembly, and shows that the wires do not have to actually abut or
lie in the identical plane.
FIG. 46 shows a wire 250 with an adjacent wire 251 and with a
plastic covering 252. Another type of square-wave pattern is shown
giving a different pattern, and again the length of the cycle is
shown.
FIG. 47 shows another form of pattern. In this case, a wire 255
actually overlaps itself with a succession of circles, so that no
one wire actually lies in a single plane, but there is, of course,
substantially a planar configuration. The successive wires abut
each other.
FIG. 48 shows another square wave configuration with steps down and
up, with wires 260, 261, etc., and plastic coating 262.
FIGS. 49 and 50 show an angular configuration and two different
uses of the same wire 265 and coating 266. In FIG. 49 the adjacent
wires are reversed to make big spaces in between, while in FIG. 50
the successive wires are parallel, to make trapezoids that are (in
each row) alternately inverted. The effects are different but use
the same wires. Note also that in FIG. 50 an additional wire 267 is
used; this wire 267 is of different length and shape and therefore
of different vibration frequency from the wires 265 and so provides
a snubbing action against bounce.
FIG. 51 shows overlapped wires 270, 271 covered by a coating 272
which fastens the wires 270 and 271 together, with one wire 270
going under its adjacent wire 271, which in turn goes under its
adjacent wire 273, and so on.
These are only examples of what can be done. Countless other
patterns are possible.
SOME OTHER EMBODIMENTS
FIG. 52 shows the lower portion of a chair 280 having an assembly
70 serving as a seat but inverted with respect to FIG. 1. While
generally not preferable, this structure is quite usable. Here
there is a simple trough shape; i.e., the seat 70 is concave
instead of convex.
FIG. 53 shows a stool 285, with legs broken off, having a spring
seat made by an assembly 70 installed to provide double curvature,
a concave arc bent into an upper or convex arc as seen from the
side. This seat 70 was installed on the frame of the stool 285 in a
manner similar to that illustrated in FIG. 37.
The thinness of the seats and backs of this invention are
especially important. Thus, the thickness of the coated wire --
which is the seat or back thickness -- should be between 1/200 and
1/50 of the cylindrical arc length of the assembly 70, i.e., of
what is to be the span of the seat or back.
To those skilled in the art to which this invention relates, many
changes in construction and widely differing embodiments and
applications of the invention will suggest themselves without
departing from the spirit and scope of the invention. The
disclosures and the description herein are purely illustrative and
are not intended to be in any sense limiting.
* * * * *