Abstract:
A method is provided for forming a welt in a single sheet of coverstock by folding and sewing. A second method is provided for forming a welt adjacent a seam formed by sewing two sheets of coverstock together, the method requiring less selvage from one of the sheets.

Description:
FIELD 
       [0001]    This disclosure generally relates to an upholstery seam between adjoining components, in particular components used in the automobile industry. More particularly, the disclosure relates to improved seams which may include a welt. 
       BACKGROUND 
       [0002]    In the automotive industry, there continues to be an effort to create vehicles having aesthetically pleasing exterior and interior designs. The importance of appearance and aesthetic appeal in the automotive interior continues to grow. In particular, attractive upholstered coverings for interior trim, seats, ornamental roof caps and steering wheels aid in selling the modern, high-quality automobile. Customer quality demands continue to raise the bar for potential owner acceptability, and aesthetic appeal has become a critical factor in the marketing of higher profit margin vehicles. One example of such improved aesthetics involves the appearance of seams in upholstered interior and exterior components. In addition, methods of reducing manufacturing costs involved with trim components continue to be needed. 
         [0003]    Seams in coverstocks for interior and exterior automotive components may be included simply to break up a broad expanse of material, to accentuate styling lines, to connect different materials together, to allow conformability of the stock to curved surfaces (as in seating) and in the case where the complexity of the curved surface being covered cannot be accomplished with a single sheet of material. 
         [0004]    One type of prior art seam that is used on many automotive vehicle interior components, including seats, is a French seam that presents a neat appearance for a joint which joins two pieces of material together at a secured seam. Prior art French seams have been made by applying a foam material to the back side of the leather, vinyl or other types of coverstock to ensure that the foam is secured to the coverstock. One portion of a first material may then be sewn to a portion of a second material. Then the edges may then be flipped over each other and stitches placed a predetermined distance from the joint seam to create a French seam look. The French seam gets the appearance from the foam being compressed on itself creating a hump-like appearance adjacent to the seam thus creating the look that is desired by many automobile designers. 
         [0005]    Welts are originally known from the upholstery industry and are generally a rod-shaped element that is bonded, welded or stitched to the coverstock of the upholstery. The welt may be attached along the edges of the upholstery and may be used to position the coverstock in accordance with the shape of the underlying cushion. Conventional welts may comprise a flexible welt core sheathed in a covering material and a laterally protruding welt flap. The sheathing may comprise cut strips of covering material which may be placed around the welt core and bonded or stitched at the ends. The welts produced in this way may then be stitched onto the edges of the sown material. 
         [0006]    In addition, welts have been used in the automobile industry, particularly on seats, head rests and arm rests. These welts are mainly used for covering otherwise visible joints between two sheets of material and may be integrally formed by folding the coverstock and creating a standard deck seam as is shown in  FIG. 7 . In this way, these welts embellish the aesthetic appearance of the automobile interior. 
       SUMMARY 
       [0007]    In a first aspect, the present disclosure is directed at a method of forming a welt within a single sheet of coverstock, the method comprising providing a sheet of coverstock, the sheet having a front surface and a back surface, and folding the sheet over upon itself such that a first portion of the backside overlies a second portion of the backside, creating a first foldline. This may be followed by providing a needle and sewing one or more stitches S 1  through the folded sheet, the one or more stitches S 1  located at a distance from the first foldline, creating an extended welt head. This may be followed by unfolding the sheet and then folding the sheet over upon itself, around the extended welt head such that a first portion of the front surface overlies a second portion of the front surface, creating two overlying second foldlines. This may be followed by sewing one or more stitches S 2  through the folded sheet and through the extended welt head, the one or more stitches S 2  located at a distance from the second foldlines that is greater than the distance of the first stitches S 1  from the second overlying foldlines. This may be followed by removing selvage from said sheet by cutting the sheet along a line located between the second foldlines and the one or more stitches S 1 . 
         [0008]    In a second aspect, the present disclosure is directed at a method of forming an improved deck seam construction for a welt formed between two sheets of coverstock, the method comprising providing first and second sheets of coverstock, the sheets each having a front surface and a back surface and an edge and placing the first sheet on top of the second sheet with the front surface of each sheet facing the other and with the edge of the second sheet extending beyond the edge of the first sheet. This may be followed by providing a needle and sewing one or more stitches S 1  through the first and the second sheets, the one or more stitches S 1  located closely adjacent the edge of the first sheet, creating a seam. This may be followed by folding the edge of the second sheet under the first sheet such that the back surface of the sheet overlies the front surface of the second sheet and sewing one or more stitches S 2  through the first and second sheets, the one or more stitches S 2  located closely adjacent to the edge of the second sheet thereby forming a welt between S 1  and S 2    
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The above-mentioned and other features and advantages of this disclosure, and the manner of attaining them, will become more apparent and the disclosure will be better understood by reference to the following description of embodiments taken in conjunction with the accompanying drawings, wherein: 
           [0010]      FIG. 1  is a side view of a piece of coverstock used to cover shaped articles according to the present disclosure. 
           [0011]      FIG. 2  is a side view of the coverstock of  FIG. 1  folded onto itself for deck stitching. 
           [0012]      FIG. 3  is a side view of the coverstock of  FIG. 2  after being deck stitched. 
           [0013]      FIG. 4  is a side view of the coverstock of  FIG. 3  unfolded over onto itself for join stitching. 
           [0014]      FIG. 5  is a side view of the coverstock of  FIG. 4  after the join stitching is complete. 
           [0015]      FIG. 6  is a side view of the coverstock of  FIG. 5  wherein the excess selvage has been removed to yield a finished seam with welt. 
           [0016]      FIG. 7  is a side view of the coverstock of  FIG. 1  which has been attached to a second sheet of coverstock and formed into a standard deck seam. 
           [0017]      FIG. 8  is a side view of the coverstock of  FIG. 1  which has been attached to a second sheet of coverstock, in a second embodiment according to the present disclosure, which uses less material by reducing the selvage of the coverstock of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention. 
         [0019]    In a first exemplary embodiment, a welt may be formed in a single sheet of coverstock and yield an excellent appearance.  FIG. 1  illustrates a side view of a sheet  10  of coverstock which includes a face layer  20  and a layer of foam backing  30 . The face layer may comprise a fabric layer, leather or a polymer, such as vinyl, polyurethane and polyolefin, or fiber-reinforced versions of those polymers. The foam backing layer  30  may be applied to the face layer  20  by lamination, by adhesive, by molding liquid precursors or by applying the foam layer with a doctor blade while the foam is liquid. 
         [0020]    To produce a welt in a sheet of coverstock, according to the present disclosure, the sheet  10  having ends  12  and  14  first will be folded onto itself such that the backside or foam layer  30  surfaces are in contact. This is illustrated in  FIG. 2 . This then leaves the two ends of the sheet,  12  and  14  pointing in the same direction. The sheet  10  may then be placed on a flat surface  60  and the foldline  22  of the face layer  20  placed against a vertical surface or fence  50 . In addition, a needle  40  may be placed an appropriate distance from the fence  50  such that one or more welt stitches  42  may be sewn through the ends  12 ,  14  to form an extended welt head  16 . This is shown in  FIG. 3 . 
         [0021]    Next, as shown in  FIG. 4 , the ends  12 ,  14  of the sheet  10  are separated from one another such that the face layer  20  surfaces of the sheet are facing or overlying one another (essentially in the shape of a “W”). The foldlines  32 ,  34  of the foam layer  30  are then placed against the fence  50  and the needle  40  used to form one or more join stitches  44  as is shown in  FIG. 5 . 
         [0022]    In  FIG. 5 , the ends  12 ,  14  of the sheet  10  have been rotated 90° or back into the original position as a flat sheet. An aesthetically pleasing, and in this instance a symmetrical welt  18  has now been formed which protrudes slightly from the surface of the sheet  10 . All that remains is to trim the selvage adjacent the foldlines  32 ,  34  from the sheet  10 . 
         [0023]      FIG. 6  illustrates the finished sheet  10  of coverstock including a welt  18  formed by inserting stitches  42  and  44  into the folded sheet. The excess material or selvage (bottom portions of the “W”) has been trimmed off by cutting along line AA. The finished sheet of coverstock may then be used to attractively cover any number of flat or curved surfaces. Accordingly, a welt has been formed in a single sheet of material. 
         [0024]    In a second exemplary embodiment, the sheet  10 ′ of coverstock may be attached to a second sheet  100  to form a welt  18 ′ adjacent a seam  80  between the two sheets.  FIG. 7  illustrates a conventional construction for a standard deck seam. To create the welt, two sheets of material  10 ′ and  100  are placed face-to-face along an edge  14 ′,  112  and one or more join stitches  46  are sewn to connect the sheets together adjacent that edge and form a seam  80 . The end  14 ′ of the first sheet  10 ′ and the matching end  112  of the second sheet  100  are then folded to one side of the seam  80  made by stitch  46  (in the case of  FIG. 7 , to the left) such that the first sheet  10 ′ is folded over beneath itself and the back surfaces of the foam layer  30 ′ are in contact. This results in the end  112  of a second sheet  100  lying under the fold of the first sheet  10 ′ to form three layers of material. 
         [0025]    Next, one or more second stitches  48  may be sewn through all three layers which may locally compress the surface of the first sheet  10 ′ and form a welt  18 ′. 
         [0026]    One disadvantage of this construction is that when used as a coverstock for a relatively thin article or over a flat surface (as on a door panel), the three layers of coverstock may create an unsightly appearance (bump) at the seam/welt. This is particularly true for thicker more plush feeling coverstocks, where the foam layer may be in the order of 6 mm. thick. In addition, this construction provides two edges  14 ′,  112  of selvage or waste material which represent an opportunity for cost reduction of this construction. 
         [0027]    The word “selvage” as used herein is understood to mean an excess portion of a sheet of material which may be trimmed off, and as such may be waste or used by recycling. 
         [0028]      FIG. 8  illustrates an improved welt construction where a more prominent welt  18 ″ may be formed by first shortening the end  14 ′ of the first sheet  10 ′ and sewing one or more stitches  46  closely adjacent the end  14 ′ of sheet  10 ′. Next, as with the construction in  FIG. 7 , the extended end  112  of the second sheet  100  is then folded to one side of the seam  80  made by join stitch  46  (in the case of  FIG. 8  to the left) such that the second sheet  100  is beneath the first sheet  10 ′ and the back surface of the foam layer  30 ′ is in contact with the face layer  120  of the second sheet  100 . This results in the end  112  of a second sheet  100  lying under the first sheet  10 ′ to form only two layers of material. 
         [0029]    Next, one or more deck stitches  48  may be sown through the two layers which may locally compress the surface of the first sheet  10 ′ and form a welt  18 ″ wherein the end  14 ′ of the first sheet  10 ′ is trapped between the sheets  10 ′,  100  and caused to form a hook configuration  140 . 
         [0030]    Thus, an improved welt line is formed having a more prominent feature and a seam having a reduced thickness of about 50%. Further, a significant amount of trim waste or selvage  14 ′ is eliminated providing a savings in material usage, particularly for high volume applications of this invention, such as in the automotive industry. 
         [0031]    It is contemplated that the welts and seams as disclosed herein may be formed from a coverstock which does not include a foam backing, that is, comprising face goods only. 
         [0032]    It is further contemplated that the features of the present disclosure may find use in suitable applications in other transportation industries as well as in upholstery for the home and office. 
         [0033]    While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.