U.S. patent number 3,708,367 [Application Number 05/139,860] was granted by the patent office on 1973-01-02 for replacable seat insert and process of making.
This patent grant is currently assigned to The General Tire and Rubber Company. Invention is credited to Bernard Carrington Grant, John F. Reilly.
United States Patent |
3,708,367 |
Grant , et al. |
January 2, 1973 |
REPLACABLE SEAT INSERT AND PROCESS OF MAKING
Abstract
This invention concerns a replaceable insert for flare-edged,
fully supported type chairs that combines the features of a rigid
yet flexible base, a cushion, a nonwrinkling, nontearable cover,
and resilient edge clamping means in one integral unit and to a
novel method of making the insert. This seat insert is
characterized by low manufacture and material costs as well as the
absence of metal fasteners and other adjustable implements thus
eliminating special installation skills and tools.
Inventors: |
Grant; Bernard Carrington
(Sylvania, OH), Reilly; John F. (Toledo, OH) |
Assignee: |
The General Tire and Rubber
Company (N/A)
|
Family
ID: |
22048745 |
Appl.
No.: |
05/139,860 |
Filed: |
May 3, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
63371 |
Aug 13, 1970 |
3647260 |
|
|
|
Current U.S.
Class: |
156/267;
156/285 |
Current CPC
Class: |
A47C
27/16 (20130101); B32B 27/065 (20130101); A47C
31/023 (20130101); B32B 27/304 (20130101); A47C
7/02 (20130101); B32B 27/12 (20130101); A47C
7/185 (20130101); B32B 7/12 (20130101); B32B
2266/0278 (20130101); Y10S 297/01 (20130101); B32B
2262/0269 (20130101); B32B 2601/00 (20130101); B32B
2266/06 (20130101); Y10T 156/108 (20150115) |
Current International
Class: |
A47C
7/02 (20060101); A47C 31/00 (20060101); A47C
31/02 (20060101); B32b 031/00 (); B29c
017/00 () |
Field of
Search: |
;156/285,286,267,252 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Drummond; Douglas J.
Parent Case Text
This application is a division of copending patent application Ser.
No. 63,371, filed Aug. 13, 1970, now U.S. Pat. No. 3,647,260,
patented Mar. 7, 1972.
Claims
What is claimed is:
1. A method of making a replaceable seat insert for a
fully-supported type chair comprising the steps of:
a. vacuum forming a base, consisting of a sheet of about 50 mil
thick acrylonitrile-butadiene-styrene resin, to the contour of said
chair support wherein said sheet is roughened on the surface that
is subsequently covered with a cushion layer;
b. forming a plurality of apertures in said base at the deepest
drawn portion thereof;
c. trimming the periphery of said base to the non-flared outline of
said chair support;
d. applying a thin coat of contact cement to the roughened surface
of said base;
e. applying a cushion layer comprising a contact cement coated
layer of open-celled flexible polyurethane foam, between about
one-quarter to about one inch thick, to the cement coated surface
of said base;
f. trimming the periphery of said cushion layer to the outline of
said base;
g. applying a thin coat of contact cement to the exposed surface of
said cushion layer;
h. vacuum forming a nonwrinkling and nontearable cover layer
consisting of a contact cement coated nylon knit-backed sheet of
flexible, expanded polyvinyl chloride resin, that is uniformly
slightly larger in area than said base, by its knit-backed side to
said layer of foam; and
i. sewing a polyvinyl chloride-based extruded clamp onto the
overhanging periphery of said cover sheet, wherein said clamp is in
the general shape of a question mark wherein the major hook-shaped
portion clasps the flared-edge of said chair support and wherein
said minor hook-shaped portion is sewn against said cover
layer.
2. A method of making a replaceable seat insert for a flare-edged
fully supported type chair comprising the steps of:
a. forming a rigid yet flexible plastic chair supporting base sheet
to the contour of the chair support and trimming the periphery
thereof to the non-flared outline of said chair support;
b. placing at least one aperture in said base at the deepest drawn
portion thereof;
c. adhering a cushion layer, comprising a relatively thin layer of
open-celled flexible foam, to the opposite surface of said base
sheet;
d. adhering a nonwrinkling and nontearable cover layer, comprising
a fabric-backed sheet of expanded flexible polymeric material, to
said cushion layer wherein said cover layer is uniformly slightly
larger in area than said base so as to provide an overlapping strip
of said material extending slightly beyond the periphery of said
base; and,
e. joining resilient clamping means onto said overlapping strip of
said cover layer, said resilient clamping means being adapted to
secure said overlapping strip to the flare edge of said chair by
applying forces in opposed directions to force said flare edge
against said overlapping strip and thereby to fasten said
replaceable seat insert to said chair.
3. The method of claim 2 wherein the step of forming the rigid yet
flexible base sheet is accomplished by vacuum forming.
4. The method of claim 2 wherein said base sheet is roughened on
the surface that is to receive said cushion layer prior to forming
it to the contour of the chair support to enhance the adhesion
therebetween.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of upholstery. More
particularly, this invention relates to the field of replaceable
upholstery parts, namely, replaceable seat inserts for chairs.
2. DESCRIPTION OF THE PRIOR ART
In the field of upholstery for chairs and other support devices,
there exist many types and designs of replaceable upholstery parts
therefore such as seat inserts. There are inserts that contain
rigid edges that snap into recesses in the chair support (U.S. Pat.
Nos. 2,901,028 and 3,019,051); there is the cushion type of insert
having a rim containing metal or rope for tightening over the
perimeter of the chair (U.S. Pat. No. 3,174,797); there are cushion
inserts having rims to be bolted or clamped to the chair frame
(U.S. Pat. Nos. 3,182,377 and 2,186,301); there is the cushion type
of insert that is pinched into narrow hook-shaped channels in the
chair frame (U.S. Pat. No. 3,126,229); there are cushion inserts
that are wedged and glued to the chair frame (U.S. Pat. Nos.
2,233,986 and 3,273,178); there is the cushion insert that is glued
and/or resiliently clamped (U.S. Pat. No. 3,281,185); there is the
cushion insert that has a cover which contains integral resilient
edge clamping means (U.S. Pat. No. 3,216,029); and there is the
rigid chair insert that has integral split tube clamping means
(U.S. Pat. No. 3,061,374). All of these various types of
replaceable upholstery inserts have certain disadvantages.
Specifically, they are either too costly to manufacture in large
quantities or require skilled or semiskilled technicians to effect
their replacement in the chair.
The rising crime rate has in large part taken the form of vandalism
of public and private property. This has manifested itself to a
large extent in the slashing and cutting of pieces of public
furniture such as chairs and seats in public transportation
vehicles and demolishing of chairs in bus, airport, and train
stations. Such damage requires that the replacement upholstery
insert be not only installable by nonskilled workers, but of
relatively low cost.
If the chair support recesses are damaged by vandals, the snap-in
type of cushions become difficult to insert in the chair;
replaceable inserts having perimeter tightening devices and bolts
tend to tear at the cover layer and, in addition, require at least
semiskilled personnel to effect installation; cushion inserts that
are pinched into place tend to come loose during heavy usage, such
as by a heavy flow of occupant traffic in a bus station; glued and
wedged seat inserts require that the old glue be scraped away and
that a period of time be set aside for the new glue to set or dry;
many of the resilient edge clamping means require sharp hook-shaped
supports that are easily damaged and if made from metal tend to
rust and corrode; and rigid seat inserts containing split tube
support means for fixing to a tubular frame are excessively
expensive as the whole chair support must be replaced. The present
trend of using inexpensive plastic films and sheets in construction
of replaceable inserts has proved unsuccessful to a large extent
because of the combined properties of most plastics known as
"memory" and "stretchability"; many rigid plastic pieces undergo
slow deformation at room temperature to their original
configuration (hence, a memory) and many soft plastic cushion
covers stretch upon usage and become wrinkled and lose their
aesthetic appeal.
This invention is a replaceable seat insert for a flare-edged,
fully supported type chair that overcomes to a great extent these
aforementioned problems. The cost of the insert is low, both in
terms of material and labor required to manufacture it; the insert
may be installed on the chair by nonskilled workers; and the insert
retains its shape and smooth surface over a wide range of
temperatures and under heavy usage.
Therefore, the main object of this invention is a replaceable seat
insert for a flare-edged, fully supported type of chair that is low
cost and easily put into use. Other objects include a unique method
of manufacturing said insert combining a number of different
polymeric materials in a unique combination utilizing inexpensive
bonding and other retaining means to effect construction of the
insert at a low cost. These and other objects will become more
apparent upon reading the Description of the Preferred Embodiment
in conjunction with the drawings attached hereto.
SUMMARY OF THE INVENTION
This invention concerns a replaceable seat insert for a
flare-edged, fully-supported type chair comprising in combination a
rigid yet flexible base conforming to the contour and to the
non-flared outline of the chair positioned by one surface against
the chair support, the base having at least one aperture in the
deepest drawn area thereof; a cushion layer comprising a relatively
thin layer of open-celled flexible foam adhered to the opposite
surface of the base; a nonwrinkling and nontearable cover layer
comprising a fabric-backed expanded sheet of flexible polymeric
material adhered by its fabric-backed side to the cushion layer,
and being uniformly slightly larger in area than the base so as to
provide an overlapping strip of material extending slightly beyond
the periphery of the base and cushion layer; and resilient clamping
means joined to the overlapping strip of cover layer for anchoring
engagement with the flare-edge of the chair support. This invention
also concerns a method of making the aforedescribed seat
insert.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional side view of a typical flare-edged,
fully supported type chair showing the replaceable seat insert of
this invention in position.
FIG. 2 is a cross-sectional view of the flared edge of the chair of
FIG. 1 and in particular shows the insert of this invention
positioned thereon.
FIG. 3 is a cross-sectional view of one embodiment of the resilient
clamping means of this invention in its relaxed condition.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings wherein like elements are identified
by like numerals throughout the three figures, FIG. 1 shows in
cross-section a typical flare-edged, fully-supported type chair and
comprises in combination a pedestal 1 that surrounds a large
portion of the seat and back of the chair and is connected to or
integral with leg 3 that is in turn connected to or integral with
platform 5 for mounting or resting directly on floor 7. Pedestal 1,
leg 3, and platform 5 may be made of virtually any solid material
such as metal, wood, plaster, plastic, or concrete; usually a
plastic or concrete is used. Full chair support 9 is positioned on
pedestal 1 and is a contoured unitary structure of a size to
include the back and seat portion of a typical chair. Full chair
support 9 may be made of a number of different rigid materials such
as wood, metal, and plastic; however, the latter construction is
becoming extremely popular, especially a rigid material known as
fiber reinforced polyester resin (FRP) that comprises glass or
other type fibers embedded in a cured polyester resin thermosetting
plastic. This construction is not only inexpensive, but FRP
materials are chemically inert, resistant to corrosion and
hydrolytic degradation, relatively insensitive to thermal changes,
and have other features which make them desirable for use where
heavy occupant traffic is in existence. Full chair support 9 is
termed "full support" because it extends fully around the chair
including the back, seat and portion joining the two; this is in
contrast to a "partial support" that includes only a portion of the
back, seat, or portion joining the two. Full chair support 9 is
fastened to pedestal 1 by most any conventional means, one form
shown here as counter-sunk machine screws 11 that pass from support
9 into pedestal 1. Full chair support 9 terminates at its periphery
in flared-edge 13 which comprises in cross-section a rearwardly
directed gentle curve. Flared edge 13 performs a number of separate
function; it is the connecting portion of full chair support 9 to
the replaceable seat insert of this invention and, in addition, the
curvature of edge 13 provides the periphery of support 9 with
additional rigidity. Moreover, flared edge 13 being a rearwardly
directing curve places the edge of full chair support 9 out of
contact with an occupant seated in the chair so as to reduce the
possibility that he or she would snag their clothing on it as well
as lowering the incidence of wear on the clamping means.
Positioned on full chair support 9 is seat insert 15 of this
invention. Insert 15 is contoured to cover all of full chair
support 9 including the back and bottom portion thereof so that the
term "seat insert" will be taken hereafter to mean a unitary
structure including the back, sides, and bottom portion of a chair
support.
Referring to FIG. 2, there is shown in combination a rigid yet
flexible base 17 that conforms to the contour of full chair support
9 and whose outline conforms to the non-flared outline of chair
support 9. This is particularly important to the operability of
insert 15 because, as will later be seen, the size of base 17 must
be maintained at less than the full, flared outline of full chair
support 9 to permit the other components of insert 15 to function
as designed. Atop base 17 or, in other words, on the opposite
surface of base 17 from that resting against chair support 9, is
cushion layer 19 that comprises a relatively thin layer of
open-celled flexible foam in bonded adherence with base 17. As will
be described later in more detail, it is imperative that cushion
layer 19 be made of an open-cell foam. Cushion layer 19 is adhered
to base layer 17 by conventional cements or adhesives, the
preferred type being a contact-type adhesive. Atop cushion layer 19
is nonwrinkling and nontearable cover layer 21 that comprises a
fabric-backed expanded sheet of flexible polymeric material that is
adhered by its fabric-backed side to cushion layer 19 by an
adhesive and that is uniformly slightly larger in area than base 17
and cushion layer 19 so as to provide an overlapping strip 23 that
extends slightly beyond the periphery of base 17 and cushion layer
19. Onto strip 23 is joined resilient clamping means 25 that is
snapped into anchoring engagement with flare edge 13 of chair
support 9.
Base 17 is termed "rigid yet flexible" to denote that while it is
not totally rigid, it is far short of being considered flexible.
Primarily, base 17 is a rigid plastic material that may be formed
such as by vacuum forming to the contour of full chair support 9.
Preferable in this respect is a vacuum-formable thermoplastic
material known as acrylonitrile-butadiene-styrene (ABS) resin
because of its low cost, light weight, and easy formability. The
thickness of base 17 should be sufficient so that the particular
plastic is restrained from "memory" deformation or reversion to its
former shape and should not be so thick that it will crack under
vacuum forming in the areas of high curvature or deep draw. In
respect to the ABS resin, it has been found that a 50 mil thick
sheet of resin is both easily vacuum formed and is sufficient to
overcome memory deformation. At the deepest drawn or deepest
contoured portion of base 17 is placed at least one and preferably
a plurality of apertures 27. These apertures serve a dual function;
they permit subsequent vacuum forming of cover layer 21 (to be
disclosed more fully later) and, during use of the chair by an
occupant, they permit air to escape from collapsed or partially
collapsed cushion layer 19 along the surface between full chair
support 9 and the abutting surface of pedestal 1. Without apertures
27 in base 17, the occupant gets the uncomfortable feeling that he
or she is sitting on a balloon wherein the air entrapped in the
cushion layer cannot escape and causes a bulge elsewhere in insert
15; moreover these bulges tend to delaminate cover layer 21 from
cushion layer 19.
Base 17 may be formed from a wide variety of materials; in addition
to the preferred material of acrylonitrile-butadiene-styrene (ABS)
resins, other resins and resinous materials may be used, such as
acetyl resins, acrylics, alkyd resins, amino resins, cellulosics,
epoxies, fluorocarbons, phenolics, polystyrene, polyamides,
polycarbonates, polyesters, polythenes, polypropylene, and vinyl
and vinyl copolymer materials, such as polyvinyl chloride, vinyl
chloride-vinyl acetate copolymers, vinyl chloride-vinylidene
chloride copolymers, polyvinyl acetate, polyvinyl alcohol,
polyvinylidene chloride, polyvinyl carbazole, polyphenylene oxide,
phenoxy resins, ionomer resins, poly 4-methyl pentene-1,
polyallomers, and the like. Both thermosetting and thermoplastic
polymeric materials are usable as base 17; however, for cost and
manufacturing reasons, vacuum formable thermoplastic materials such
as ABS resins are preferred.
Cushion layer 19 is comprised of a relatively thin, i.e.,
one-quarter to 1 inch and preferably one-half inch thick layer of
open-celled flexible foam. It is necessary that the foam be
open-celled to enable subsequent vacuum forming of cover 21 by the
method of this invention and also to allow air to escape from and
return to cushion layer 19 during use of insert 15 by an occupant.
A preferred material for cushion layer 19 is flexible polyurethane
foam because of its good aging properties, its resistance to
mildew, etc., however, other materials may be used such as
reticulated polyethylene or polypropylene foam, open-celled
polyvinyl chloride foam, and other similar materials. Cushion layer
19 is adhered to base 17 by an adhesive that is preferably coated
on both cushion layer 19 and base 17. Generally speaking, a
contact-type cement is preferred for this construction.
Over cushion layer 19 is placed cover layer 21 that comprises a
relatively thin, i.e. 10-200 mils, nonwrinkling and nontearable
fabric-backed expanded sheet of flexible polymeric material that is
uniformly slightly larger in area than both base 17 and cushion
layer 19 so as to provide overlapping strip 23 that extends
slightly beyond the periphery of base 17 and cushion layer 19.
Cover layer 21 is adhered to cushion layer 19 by its fabric-backed
side; in other words, the fabric-backed side of cover layer 21 is
in contact with cushion layer 19 through a layer or layers of
adhesive. Preferred in this respect is also a contact-type
adhesive. Note should be made that cushion layer 19 may be of the
same area and size as base 17 or may be slightly larger as there is
a small area 27 between the end of base 17 and clamping means 25
for collapsed cushion layer 19 to occupy. It is essential that
cover layer 21 be made from a nonwrinkling and nontearable material
such as a fabric-backed polymeric material so that it will not
pucker and fold during extended use. However, this material while
nonwrinkling and nontearable in normal use, i.e., when used on the
seat insert at or near room temperature, is sufficiently
stretchable to permit it to be vacuum or heat formed--usually by
heating it and subjecting it to pulling and stretching (via vacuum
or press head) to conform it to the desired contour. In addition,
the nonstretchability of cover layer 21 at or near room temperature
works in combination with clamping means 25 to ensure that the
latter does not loosen during extended use of insert 15. Many types
of fabric-backed materials may be used, preferred is a nylon-backed
expanded sheet of flexible polyvinyl chloride plastic because of
its low cost and the fact that it is vacuum formable. Generally
speaking, cover layer 21 is vacuum formed or otherwise formed
against cushion layer 19 so that in its relaxed position it is
tight and nonwrinkled over the entire surface of insert 15.
Nonwrinkling and nontearable (and relatively nonstretchable at or
near room temperature) cover layer 21 may be comprised of a variety
of materials. The fabric layer may be chosen from a variety of
weaves such as knits, straight weaves, and nonwovens; however, it
has been found that the knit weave permits a greater degree of
vacuum forming and at the same time provides a high degree of tear
resistance to layer 21 over a wide temperature range; a knit nylon
is preferred herein for its strength and ease in vacuum forming.
The flexible polymeric material comprising the rest of cover layer
21 may be chosen from a wide range of materials such as vinyl
polymers and copolymers, for example, plasticized polyvinyl
chloride, vinyl chloride-vinyl acetate copolymers, vinyl
chloride-vinylidene chloride copolymers, vinyl acetate copolymers,
polyvinyl alcohol, polyvinylidene chloride, polyvinyl carbazole,
and blends of polyvinyl chloride with various elastomers such as
polyvinyl chloride-nitrile rubber blends, etc. It is preferred that
cover layer 21 be of an expanded type of material, i.e., having at
least one foam layer therein. This may conventionally be done by
mixing the thermoplastic flexible material, such as vinyl material,
with a blowing agent such as azodicarbonamide,
azodiisobutyronitrile, benzenesulphonhydrazide,
benzonesulphonhydrazide, p-toluene sulfonyl semicarbazide, N,N'
dimethyl N,N' dintrosoterphthalamide, trihydrazino triazine,
nitrogen, carbon dioxide, pentane, fluorocarbon 11, fluorocarbon
12, fluorocarbon 114, and methylene chloride with the
thermoplastic, calendering the material into a sheet, and then
heating it to the point wherein the blowing agent gasifies and
forms a cellular structure within the sheet. This is desired in
cover layer 21 so as to provide additional cushioning for insert 15
and to hide any strike through of the fabric backing. Cover layer
21 may be kept nonfoamed (unexpanded) until the time it is vacuum
formed during its adherence to cushion layer 19 and then raised in
temperature to not only gasify the blowing agent within the layer
but to smooth out any wrinkles that may have developed in the
vacuum forming step. Cover layer 21 may be pigmented or otherwise
colored to show a wide variety of decorative colors and in addition
may be printed, laminated, or otherwise decorated to any desired
design.
Onto strip 23 is joined resilient clamping means 25. One embodiment
of clamping means 25 is shown in cross-section in FIG. 3 and
comprises a semi-flexible extruded polymeric material in the
general shape of a question mark wherein the major hook-shaped
portion 29 is snapped over flared-edge 13 and wherein minor
hook-shaped portion 31 is sewn or stapled to strip 23. The channel
or depression formed by minor hook-shaped portion 31 in the outer
surface of means 25 permits the stitches or staples to be hidden
from view which not only provides for a more pleasing aesthetic
appearance but maintains the stitches or staples out of contact
with occupants or objects that come against clamping means 25
thereby ensuring a longer life for the joining structure, i.e.,
stitches or staples. Other embodiments of clamping means 25 are
possible and are fully contemplated herein. Note that strip 23 is
folded back upon itself under clamping means 25, as shown in FIG.
2; this is an optional treatment of strip 23 for it may be trimmed
near the stitches that pass through minor hook-shaped portion 31;
however, trimming strip 23 back to this area invites the fabric
backing of cover layer 21 to unravel during severe stress.
Therefore, it is preferred to merely fold strip 23 back upon itself
at the sewn or stapled portion to ensure a more rigorous affixation
to clamping means 25. Preferably, clamping means 25 is made of an
extruded polyvinyl chloride based material that is rigid yet
flexible however more flexible than base 17, however other polymers
are usable such as elastomers for example butadiene rubber,
isoprene rubber, chloroprene rubber, acrylate-butadiene rubber,
isobutylene-isoprene rubber, nitrile-butadiene rubber,
nitrile-chloroprene rubber, pyridine-butadiene rubber,
styrene-butadiene rubber, styrene-chloroprene rubber,
styrene-isoprene rubber and elastomer-plastic blends for example
nitrile rubber-polyvinyl chloride blends, urethane rubber-nylon
blends, butadiene rubber-polypropylene blends, etc.
When placing insert 15 onto chair support 9, clamping means 25 must
be "opened up" by bending out major hook-shaped portion 29 and
snapping it over flared-edge 13. At this time, cover layer 21 is
stretched as far as possible so that it is thereafter held taut,
and, due to its fabric backing will remain taut throughout extended
usage. The provision that base 17 be kept to the size of the
non-flared outline of chair support 9 should now be apparent; it
permits clamping means 25 to be placed in full clasping contact
with flared-edge 13 to achieve a good anchoring position thereon.
Clamping means 25 may be affixed to strip 23 by different means
that intertwine in the fabric backing of cover layer 21 such as by
sewing or by stapling; however, sewing has been found to be the
most inexpensive as well as one of the most longest lasting
constructions.
In a separate embodiment of this invention, base 17 is roughened on
the surface that is adjacent to cushion layer 19 to enhance the
bonding therebetween. A preferred method of roughening the surface
of base 17 is to pass a sheet of base 17 material through a
calender or embossing device wherein tiny indentations are placed
in the surface; this is known in the vernacular as "hair cell
embossing." Base 17, cushion layer 19, and cover layer 21 may be
bonded together by a wide range of adhesives provided they are
compatible with the particular materials used in these elements.
Examples of adhesives usable herein include acrylic and methacrylic
adhesives, bitumen adhesives, casin, cellulose acetate and
cellulose caprate adhesives, cellulose nitrate and cyano acrylate
adhesives, epoxy polyamide adhesives, phenolic-polyamide,
phenolic-vinyl adhesives, polyamides, polyisobutylenes,
polystyrene, polyvinyl acetyl, polyvinyl acetate, rosin adhesives,
epoxies, furanes, melamine-formaldehyde adhesives, oleoresins,
phenol-formaldehyde adhesives, phenolic-epoxy, phenolic-neoprene
adhesives, phenolic-nitriles, polyester adhesives and polyurethane
adhesives, resorcinol-formaldehyde and ureaformaldehyde adhesives,
polychloroprene adhesives and acrylonitrile-butadiene adhesives.
Specifically preferred in this respect are adhesives known as
"contact" adhesives.
The process of making insert 15 is by a unique combination of steps
designed to obtain the benefits of adhesives to lower the material
cost and manufacturing costs. The first step in making the
replaceable seat insert of this invention is to vacuum form or
otherwise form base 17 from a flat sheet to the contour of the
chair support 9 and then trim the edges back to the non-flared
outline of chair support 9. Prior to this step of course the
surface of base 17, that is to be bonded to cushion layer 19, may
have been previously roughened such as by the "hair cell embossing"
step heretofore disclosed. After vacuum forming, apertures 27 are
placed (drilled or punched) in the deepest drawn or highest
contoured area of base 17. Care must be taken to ensure that the
apertures are not too large, such as over one-half inch in
diameter, etc. Thereafter, cushion layer 19 is placed in adherence
with base 17. This is preferably accomplished by precoating the
surface of base 17 and the surface of cushion 19 (a thin sheet of
open-celled flexible foam) with a contact type cement so that upon
joining of the two there is formed immediately a strong bond
therebetween. The edges of cushion layer 19 may then be trimmed to
the general outline of base 17 or, of course, it may have been
pre-cut to this size. Thereafter, cover layer 21 and the surface of
cushion layer 19 are precoated with a contact adhesive and then
cover layer 21 is vacuum formed onto cushion layer 19 and base 17
by utilization of apertures 27. During this step, cover layer 21
may be heated so that it conforms to the contour of base 17 without
wrinkling. The edges of cover 21 are trimmed to a uniformly larger
size than base 17 so as to provide strip 23. Cover layer 21 should
be vacuum formed to cushion layer 19 so that the fabric is adjacent
the surface of cushion layer 19. Such a construction permits the
wearing surface of cover layer 21 to be decorated and otherwise
finished without impairment by the presence of the fabric layer.
Next, clamping means 25 is sewn or stapled around the edge of cover
layer 21 onto strip 23. Thereafter, insert 15 comprises the
aforementioned construction and may be readily placed onto chair
support 9 and clamping means 25, snapped over flared-edge 13 of
chair support 9 to place insert 15 in tight anchoring engagement
with chair support 9.
* * * * *