BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates to a method and apparatus for making seat cushions for seat components, and more particularly, to a method for bonding a cover fabric to a cushion body using a barrier layer Iocated between the cover fabric and the forming tool surface for interfacing the cover fabric and the forming tool surface to minimize nap crush during the bonding process. 2. Description of the Prior Art

Various methods are employed for bonding a cover fabric to a foam cushion in forming seat cushions for vehicle seats. In most fabric-to-foam bonding methods, the cover fabric and the foam cushion are compressed between forming tools while a heated atmosphere is applied for shaping the cover fabric and for activating the adhesive to bond the cover fabric to the foam cushion to form a composite structure. The composite structure is then cooled to allow the adhesive to solidify.

Most known forming tools are made of metal or epoxy and thus present a hard forming surface on which the outer surface of the cover fabric is positioned. Consequently when deep nap cover fabrics are bonded to a foam cushion, compression of the cover fabric and foam cushion between the forming tools during the bonding process frequently results in the nap fibers of the cover fabric being crushed. Because the bonding process is carried out under conditions of a heated atmosphere, the crushed nap of the fabric will take a permanent set when the seat cushion is cooled.

In known methods for bonding a fabric to foam, the heated atmosphere used is low pressure steam, which can be saturated or superheated steam. It is known that fabric-to-foam bonding systems that use low steam pressure are sensitive to relatively small changes in process parameters. For example, a slight decrease in steam pressure can result in reduction of the operating temperature to a value that is below the temperature needed to activate the adhesive. Consequently, most methods for bonding a fabric to a cushion body require preheating of the forming tool prior to supplying the heated atmosphere to the forming tools. It is known that the susceptibility to nap crush is increased when the forming tools used are preheated because this requires that the cover fabric be held in engagement with a heated tool for a longer period of time. Both the use of a heated tool and the compression pressure that is required in the bonding operation contribute to nap crush. Another consideration is that in most known fabric-to-foam bonding processes, the type of adhesive that is used is dictated by a desire to avoid nap crush. This places constraints on the bonding process. For example, many fabric-to-foam bonding systems employ a hot melt adhesive that has a softening point of 230 °F because the use of such relatively low melt point adhesive,

minimizes the possibility of nap crush that could otherwise be caused by applying excessive heat to the fabric for an extended period of time.

Summarv of the invention The present invention provides a method and apparatus for making seat cushions for seating components. In accordance with the invention, a barrier layer is Iocated between the forming surface of a forming tool and a cover fabric to be bonded to a cushion body. The barrier layer provides a yieldable and yet resilient surface for interfacing the cover fabric with the forming tool during the bonding process for minimizing crushing of the nap of the cover fabric. More specifically, in accordance with the invention, the barrier layer comprises a fabric including a base material having a plurality of long rod-like elements or bristles that project outwardly from the base material, in a spaced relationship defining voids or cavities on the surface of the barrier fabric which receive the nap fibers when the cover fabric and the cushion body are being compressed by the forming tools. The barrier fabric cushions the nap fibers, absorbing the affects of the compressional force of the forming tools during the bonding process which results in minimizing of nap crush.

The invention consists of certain novel features and structural details hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the present invention.

Description of the Drawings

FIG. 1 is a cross-section view of forming apparatus for making seat cushions for seating components, illustrating the raw materials for forming the seat cushion in their unaltered state with a cover fabric and a cushion body Iocated between upper and Iower forming tools, and illustrating a barrier fabric on the Iower forming tool Iocated between the forming tool surface and the cover fabric in accordance with the invention;

FIG. 2 is a view similar to FIG. 1 and showing the forming tool operated to compress the seat component materials during application of steam;

FIG. 3 is a top plan view of one barrier fabric for use in the method of bonding a cover fabric to a cushion body in accordance with the present invention;

FIG. 4 is an enlarged view of the portion of the barrier fabric contained within the circle in

FIG. 3;

FIG. 5 is a side elevation taken in the direction of the arrows 5-5 in FIG. 4;

FIG. 6 is a vertical section view of another barrier fabric provided by the invention;

FIG. 7 is a section view of yet another barrier fabric for use in the forming process and showing the cover fabric positioned above the barrier fabric;

FIG. 8 is a view similar to FIG. 7, and illustrating the cover fabric being compressed onto the barrier fabric as during a bonding process; and,

FIG. 9 is a perspective view of a seat cushion produced using the forming process of the invention.

Description of Preferred Embodiments The method according to the invention can be used to bond a cover fabric to a cushion body of any seating component, including furniture, vehicle seat assemblies, and the like, and is particulariy applicable to bonding deep nap cover fabrics to a cushion body. The seat component can be the seat cushion portion or the seat back portion of a seat assembly, or a seat insert component.

Referring to FIG. 9, by way of illustration, the method of the invention is described with reference to an application for producing a seat component 10, such as a seat cushion for a vehicle seat assembly, and in particular, for forming a cover fabric to a predetermined shape and bonding the cover fabric to a cushion body. The cover fabric 11 of the seat component 10, which forms a main seating surface 14 of the seating component, can have grooves 16 formed therein for stylizing the appearance of the seat cushion. The main body of the seat component 10 consists of a cushion body 17, shown in FIG. 1, for example, which is premolded or preformed to have a surface corresponding to the finished surface of the seat cushion being produced. In the exemplary embodiment, the cushion body 17 has a pair of grooves 18 in the outer surface 19 thereof, which correspond to the styling grooves 16 in the outer or occupant interfacing or "A" surface of a seat cushion (or the front surface of a seat back cushion). The cover fabric 11 is secured to the cushion body 17 by a thermally activated adhesive 15. The cover fabric 11 and the adhesive layer 15 are not sectioned in FIGS. 1 and 2 to simplify the drawings.

The outer surface 19 of the cushion body 17 can be a fibrous, cellular structure, or a surface that is designed or has been processed to promote mechanical bonding between a cover fabric and the surface of a cushion body. Examples of fibrous materials-include PET and rubberized hair. Examples of cellular structure include open or closed cell urethane foam. However, the method of the invention can also be used in producing other articles or seat

components which require bonding a cover fabric to a cushion body. The shaping and/or bonding process is carried out under conditions of a heated atmosphere, such as hot air or steam, which can be saturated or superheated. A form of steam is preferred due to its thermal transfer characteristics. The softening temperature of the exemplary adhesive is in the range of 210°F to 240°F, and is preferably about 230 °F. The adhesive used is selected as a function of different operating conditions used in the bonding process. In the exemplary embodiment, the adhesive 15 is a lay on web, such as Polymid 5200 Series, which is commercially available from Bostik. However, the adhesive can be applied to the cover fabric in any suitable form. For example, the adhesive can be sprayed onto the back surface of the cover fabric, the adhesive can be sprayed onto the cushion body, or the adhesive can be pre-laminated onto the cover fabric. The scope of the invention is intended to encompass any thermally activated adhesion process rather than use of a particular adhesive. Thus, for example, rather than a hot melt adhesive, the adhesive used to bond the cover fabric to the cushion body can include a blocking agent which is released when subjected to a heated atmosphere, allowing a chemical bonding action to occur for bonding the cover fabric to the cushion body, or for bonding together two cushion elements.

A forming apparatus 20 for shaping the cover fabric and bonding the cover fabric to the cushion body 17 is shown in FIGS. 1 and 2 as including a forming tool assembly consisting of an upper tool 22 and a Iower forming tool 24 having an upper surface 26, commonly referred to as the forming surface, that shapes the cover fabric during the bonding process. The cover fabric 1 1 is a deep nap fabric having a base portion 12 and nap fibers 13 which project from the base portion 12 as shown in FIG. 7, for example.

According to the invention, a barrier layer, in the form of a fabric material 28 or other material having a yieldable and yet resilient upper surface, is Iocated between the forming surface 26 of the Iower forming tool 24 and the cover fabric 11 for cushioning the cover fabric and its nap fibers during the bonding process. Preferably, the barrier fabric is secured to the forming surface of the Iower forming tool 24 by an adhesive or in any other suitable way. The use of a barrier fabric is a factor in minimizing the degree of nap crush because the barrier fabric "cushions" the nap side of the cover fabric by providing voids or recesses which receive the nap fibers during the portion of the bonding process as the cover fabric is being compressed between the upper and Iower tools.

The shaping and bonding process is carried out under conditions of a heated atmosphere. In the exemplary embodiment, the heated atmosphere is steam, which can be saturated or superheated which is supplied to the Iower forming tool through a steam inlet member 32. However, other heated atmospheres, such as heated air, can be used.

The Iower forming tool 24 is a generally rectangular closed box-like structure that defines a tool chamber 25. The upper surface 26 of the Iower forming tool 24 is contoured to be

complementary to the style for the occupant interfacing or "A" surface of the seat cushion being produced. The forming surface 26 has perforations 30 therethrough over substantially its entire extent through which steam supplied to the tool chamber 25 is passed to the cover fabric and cushion body during the bonding process. The size and shape of the perforations 30 can vary as a function of material, but preferably are on a grid spacing of about .375 inch to .50 inch and have diameter of approximately .035 inch to .065 inch, and preferably about .040 inch or .050 inch. The steam inlet member 32 is adapted for connection to a source 38 of a heated atmosphere, such as a source of saturated steam under pressure. The Iower forming tool 24 can be made of cast aluminum. The Iower forming tool 24 includes exhaust outlet member 34 which is adapted for connection to a vacuum source or other means for removing heat and moisture from the composite structure formed by the cover fabric bonded to the cushion body.

The upper tool 22 is a generally complementary in shape to the cushion body and can be made of aluminum or an insulating material, such as epoxy. In the exemplary embodiment, the upper tool 22 is used to move the cushion body onto the cover fabric and to apply pressure to the cushion body the cover fabric. The upper tool can have a forming surface including perforations corresponding to those in the Iower forming tool 24, and which forming surface is complementary to the forming surface 26 of the Iower forming tool 24. While the barrier fabric is described with reference to an application with a forming tool assembly that is open on all four sides, the barrier fabric can be used with other types of forming tool assemblies, including those providing a closed forming cavity.

Referring to FIG. 3, one material suitable for use as a barrier fabric includes a fabric base 40 having a monofilament woven into it and then severed, creating a plurality of monofilament segments, such as monofilament segments 41, 42 and 43, over the upper surface 44 of the material. The monofilament is of the type of material that has a memory which is beneficial during processing. By way of example, the monofilament can be the type of material used in making fish line. The monofilament segments in themselves are short, being typically about 1/4 inch in length, but are longer than the nap fibers 13 of the cover fabric. The spaces 46 between adjacent ones of the monofilament segments of the barrier fabric define voids or gaps for receiving the long nap fibers 13 of the cover fabric. The fabric base 40 is pervious to steam and air. Material of this type is available from Collins & Aikman, Roxboro, North Carolina.

Referring to FIG. 6, another material suitable for use as the barrier fabric is the loop tape portion 50 of a hook and loop material, such as the type that is commercially available under the tradename VELCRO. Such loop tape portion 50 includes a base portion 51 having plurality of upstanding rod-like projections or bristles 52 of a flexible material and having loops 54 formed at the ends thereof. The upstanding bristles 52 are resilient, semi-rigid elements that are sufficiently flexible to permit the bristles 52 to yield slightly when subjected to the compressional forces of the forming tools, and to restore when the compressional forces are removed. When the cover fabric

is subjected to the compressional forces of the forming tools, the bristles 52 support the base material 12 of the cover fabric above the forming surface, although the bristles 52 yield somewhat when compressed towards the base portion 51. The spaces 56 between adjacent bristles define voids or gaps which receive the long nap fibers 13 of the cover material. The resilient support of the cover fabric by the barrier fabric minimizes the compressive forces to which the nap fibers 13 are subjected during the bonding process. The bristles restore fully upon removal of the compressional forces, allowing the nap fibers to recover from the effects of any compression to which they have been subjected during the bonding process. Testing has demonstrated that use of this material as a barrier fabric reduces nap crush. It is believed this reduction in nap crush is the result of the nap fibers of the cover material setting in the voids or gaps formed by the bristles of the loop tape portion 50. A shortcoming of the use of this material as a barrier fabric is that the material is less permeable to steam. Moreover, this material doesn't contour well and accordingly does not closely follow the contours of the forming surface.

Referring to FIG. 7, there is illustrated a material 60 having preferred characteristics for use as a bamer fabric in the bonding process. The material 60 includes a base portion 61 that is somewhat similar to that of the monofilament containing material 40 shown in FIG. 3, in that it is pervious to steam and to air. One material that is suitable for use as this barrier fabric material 60 is a component of a self-gripping fastener commercially available under the tradename APLIX, from APLIX Incorporated. In its commercial form, the material includes rod-like projections or bristles of a flexible material such as nylon or a semi-rigid plastic, that are formed to extend peφendicular to the backing or base material 61. In the present application as a barrier fabric in a process for bonding a cover fabric to a cushion body, the material 60 is similar to in a preprocessed hook and loop commodity, that is prior to forming of the lobes on the ends of the rod-like projections or bristles of the hook element. It has been found that for application as a barrier fabric for producing seat cushions, this material functions best when used in the pre-processed condition. Thus, the material 60 includes a base material 61 having a plurality of rod-like projections or bristles 62 which project outwardly from the base material and are spaced apart, defining voids or recesses 66 which receive the long nap fibers 13 of the cover material. The resilient support of the cover fabric by the barrier fabric minimizes the compressive forces to which the nap fibers 13 are subjected during the bonding process. The bristles 62 restore fully upon removal of the compressional forces, allowing the nap fibers to recover from the effects of any compression to which they have been subjected during the bonding process. The upper portion of the material 60, represented by dashed line 64, which is engaged by the cover fabric has a fiber-like or brush-like form when in the relaxed or uncompressed condition.

The method of carrying out this invention using the forming tool assembly is illustrated in FIGS. 1 and 2. A cover fabric 11 is placed on the upper surface of the forming tool, and Iocated

on the bamer fabric 28, assumed to be made of the material 60 shown in FIG. 7. The cover fabric 11 is positioned on the barrier fabric 28 with its ocdupant interfacing or "A" surface engaging the barrier fabric and with its back surface facing upwardly as shown in FIG. 1. The cover fabric 11 is clamped to the support by suitable fixtures 37 in the manner known in the art. A layer of adhesive 15 in sheet form is placed on the back side of the cover fabric 11. Then, the cushion body 17 is positioned on the cover fabric. In FIG. 7, the cover fabric is shown positioned above the barrier fabric 28 and assumed to be prior to application of compressive force to the cover fabric and the barrier fabric so that the bristles of the barrier fabric are shown in their upright condition, extending straight up from the base fabric. The upper tool 22 is lowered down by a suitable press (not shown) to engage the cushion body 17. The upper tool 22 appjies a pressure to the cushion body, compressing the cover fabric 11 , the cushion body, and the barrier fabric between the upper and Iower tools.

Referring to FIG. 8, when the barrier fabric 28 is subjected to compression, the bristles 62 of the barrier fabric yield somewhat and are flexed downward, supporting the base fabric 12 of the cover material 11 on their tip portions. The nap fibers 13 of the cover fabric extend into the voids defined by the bristles 62. Although upper portions of the nap fibers may become slightly bent over, the nap fibers are not completely sandwiched between the base fabric and the forming surface as is the case when no barrier fabric is used. The barrier fabric 28 is secured to the forming surface 26 and assumes the configuration of the forming surface so that the cover fabric will be conformed to the shape of the forming surface.

Referring additionally to FIG. 2, when the stack of seating components is under compression, steam from the steam source 38 is supplied to the tool chamber 25 while pressure is maintained by the forming tools. In the exemplary embodiment, the steam supplied to the tool chamber is at a temperature that is sufficiently high as to activate the adhesive. The steam supplied to the tool chamber 25 passes out of the tool chamber through the perforations 30 through the cover fabric and into the cushion body 17. The steam is supplied to the tool cavity 25 for a time interval on the order of 5 to 20 seconds. The steam activates the adhesive 15 to bond the cover fabric 11 to the cushion body 17.

During the bonding process, the barrier fabric 28 Iocated between the forming surface of the forming tool and the outer or "A" surface of the cover fabric minimizes crushing of the nap fibers of the cover fabric 11 by providing voids or recesses for receiving the long nap fibers of the cover fabric during the portion of the bonding process in which the cover fabric and the cushion body are being subjected to compressional forces by the forming tools.

At the end of the time interval, the steam is discontinued and cooling gas is passed through the composite structure formed by the cover fabric and cushion body for cooling the composite structure and solidifying the adhesive. Then, the upper tool 22 is retracted to release the pressure from the cushion body and cover fabric. The clamps 37 are opened, releasing the cover fabric 22

from the support to permit the formed seat cushion to be removed from the forming apparatus for finishing. When the forming tool is retracted and the composite structure is removed, compressive forces are removed from the barrier fabric, permitting the bristles 62 to restore.

Testing has demonstrated that using the material 60 as a barrier fabric results in an improved bond between the cover fabric and the cushion body at the junction therebetween. It is believed that the reason this improved bond is due to the improved distribution of steam afforded by the fiber-like form of this material. In using this material 60, the height of the fibers is critical to type of cover fabric being protected. The greater the nap, i.e., the longer the nap fibers, the longer the rod-like projections or bristles of the material must be to provide optimum protection against nap, crush.

Those skilled in the art can now appreciate that this invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with a particular example, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification and following claims.