Abstract:
A cushion for a seat of good appearance. The cushion for a seat comprises a three-dimensional cover constituted of a front surface portion, a substantially U-shaped rear surface portion arranged oppositely to the front surface portion while spaced apart therefrom, a circumferential surface portion arranged between the front surface portion and the rear surface portion while connecting at the edge thereof with the edge of the front surface portion and the edge of the rear surface portion, a stripe portion extending downward from the upper edge of an opening in the rear surface portion to close the opening, a first pair of teeth tapes fixed to the opposite side edges of the stripe portion, and a second pair of teeth tapes provided at the opposite side edges of the circumferential surface portion corresponding, in position, to the opposite side edges of the stripe portion and engaging with or disengaging from the first pair of teeth tapes so that the opening is closed or opened by the stripe portion, and a foamed resin pad molded integrally with each component of the cover, excluding the stripe portion, in the cover.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to a cushion for a seat, in which a foam resin padding is integrated with a three-dimensional cover covering the foam resin padding and, more particularly, to a cushion in which a rear side section of a three-dimensional cover is adapted to be openable and closable with slide fastener means. 
       BACKGROUND ART 
       [0002]    As a cushion for a seat back of a seat, which is formed by causing a foam resin padding and a three-dimensional cover covering the foam resin padding to be integrated with each other by a die apparatus, there is proposed a cushion for a seat back, which is disclosed in Japanese Patent Application Laid-Open No. 2005-262628, for example. 
         [0003]    When the cushion is to be formed by the die apparatus, the three-dimensional cover is laid in the die apparatus. In this condition, expandable resin is poured into an interior of the three-dimensional cover through the die apparatus and allowed to foam, whereby a padding of the foaming resin integral with the cover is formed. In this way, a finished cushion is formed. After the finished cushion is formed and removed from the die apparatus, a seat back frame for supporting the cushion is incorporated in the padding. For this purpose, the die apparatus includes a core for forming a cavity opened at a rear side of the padding for receiving the seat back frame. When the three-dimensional cover is laid in the die apparatus, the core is inserted in the three-dimensional cover. In order that the three-dimensional cover can receive the core when it is laid in the die apparatus, a rear side section of the three-dimensional cover is adapted to be openable and closable with respect to the cover by slide fastener means. 
         [0004]    Referring now to  FIGS. 1 and 2 , the related art cushion will be discussed hereinafter in order to facilitate understanding of the present invention. 
         [0005]    Referring to  FIG. 1 , the cushion includes the three-dimensional cover  33 , in an interior of which the foam resin padding (not shown) is integrated with the three-dimensional cover  33 . The cover  33  includes a front side piece  33   a,  a rear side piece  33   c  spaced apart from the front side piece  33   a  and opposed to the front side piece  33   a,  a peripheral piece  33   b  disposed between the front side piece  33   a  and the rear side piece  33   c,  extending along peripheral edges of the front side and rear side pieces  33   a,    33   c  except lower edges of the front side and rear side pieces  33   a,    33   c,  and sewed to the peripheral edges of the front side and rear side pieces  33   a,    33   c  at edges of the peripheral piece  33   b,  and a lower side piece  34  sewed at an edge thereof to a lower edge of the front side piece  33   a.  The rear side piece  33   c  is formed substantially into a U-shape and includes a pair of spaced apart side sections  33   d,  an upper section connected to upper edges of the spaced apart side sections  33   d  and interconnecting the spaced apart side sections  33   d,  and a belt-shaped intermediate piece  33   e.  The intermediate piece is attached at an upper edge thereof to a lower edge of the upper section of the rear side piece  33   c  and is adapted to be coupled at left and right side edges thereof to inner edges of the side sections  33   d  by first and second slide fastener means, whereby an opening of the rear side piece  33   c  is openably closed by the intermediate piece  33   e.  The first slide fastener means includes a pair of first and second zipper tapes  35   a  which are provided along the left side edge of the intermediate piece  33   e  and an inner edge of a left side section of the rear side piece  33   c,  and a first slider assembly (not shown). The first slider assembly, supported by the first and second zipper tapes, is included for zipping and unzipping the first zipper tape with respect to the second zipper tape. Moreover, the second slide fastener means includes a pair of third and fourth zipper tapes  35   b  which are provided along the right side edge of the intermediate piece  33   e  and an inner edge of a right side section of the rear side piece  33   c,  and a second slider assembly (not shown). The second slider assembly, supported by the third and fourth zipper tapes, is included for zipping and unzipping the third zipper tape with respect to the fourth zipper tape. Thus, the intermediate piece  33   e  is configured so as to be separatable from the side sections  33   d  of the rear side section  33   c  by the first and second slide fastener means, so that the cover is openable at the rear side section thereof. The foam resin padding in the cover  33  is integrated with the respective sections of the cover  33  except the intermediate piece  33   e  and the lower side piece  34 . 
         [0006]    The cushion which includes the cover  33  constructed as discussed above and the foam resin padding is formed by utilizing a die apparatus  3  which is partially illustrated in  FIG. 2 . The die apparatus  3  includes a first die means  30  for forming front and rear sections of the cushion and a peripheral section of the cushion, a core  31  for forming a cavity opened at a rear side of the foam padding  36  for receiving a seat back frame (not shown), and a second die means  32  which is adapted to be combined with the first die means  30  and clamped against the first die means  30 , when the cushion is to be formed by the die apparatus. The first die means  30  is provided with a first sectional die means  30   a  for forming the rear side section of the cushion, and a second sectional die means  30   b  for forming the peripheral section of the cushion. The first sectional die means  30   a  is coupled to the second sectional die means  30   b  by a first hinge means  30   c.  The second sectional die means  30   b  is coupled to the first die means  30  by a second hinge means  30   d.  Thus, the first and second sectional die means  30   a,    30   b  can be opened and closed with respect to the first die means  30  by the first and second hinge means  30   c,    30   d.    
         [0007]    When the cushion is to be formed by the die apparatus, the second die means  32  is removed from the first die means  30 , the first and second sectional die means  30   a,    30   b  are opened with respect to the first die means  30  by the first and second hinge means  30   c,    30   d,  and the cover  33  is then laid on a die surface of the first die means  30  with the intermediate piece  33   e  being separated from the side sections  33   d  of the rear side piece  33   c  of the cover  33  by unzipping the first and third zipper tapes of the intermediate piece  33   e  from the second and fourth zipper tapes of the side sections  33   d  of the rear side piece  33   c.  Then, the core  31  is inserted within the three-dimensional cover  33  and the first and second sectional die means  30   a,    30   b  are closed with respect to the first die means  30  by the hinge means  30   c,    30   d.  At this time, each of the zipper tapes  35   a,    35   b  provided at the both side sections  33   d  of the substantially U-shaped rear side piece  33   c  is located within a space X between the second die means  32  and the core  31 , and each of the both side sections  33   d  of the substantially U-shaped rear side piece  33   c  becomes pinched by a protrusion  31   a  of the core  31  and the first sectional die means  30   a.  In this condition, the second die means  32  is combined with the first die means  30  and clamped against the first die means  30 , and expandable resin is poured into the interior of the cover  33  and foams in the interior of the cover  33 , whereby the cushion in which the padding  36  of the foaming resin is integrated with the cover  33  and formed with the cavity for receiving the seat back frame is formed. Each of the both side sections  33   d  of the substantially U-shaped rear side piece  33   c  is pinched by the protrusion  31   a  of the core  31  and the first sectional die means  30   a  as discussed above, so that the foaming resin will not adhere to a surface of the cover  33  and/or the zipper tapes  35   a,    35   b.    
         [0008]    However, in the related art cushion constructed as discussed above, the front side piece  33   a  is sewed to the peripheral piece  33   b,  and the peripheral piece  33   b  is sewed to the rear side piece  33   c,  so that there are many sewed portions between the front and rear side pieces  33   a,    33   c  and the peripheral piece  33   b,  thus detracting from the visual appearance of the cushion. 
         [0009]    Moreover, if it is necessary to provide a pocket on a rear surface of the related art cushion, the pocket is obliged to be provided on the belt-shaped intermediate piece from the viewpoint of facilitating the assembling of the cushion. Therefore, only a pocket having a narrow width can be provided on the intermediate piece but a pocket having a wide width can not be provided on the intermediate piece. 
       DISCLOSURE OF THE INVENTION 
       [0010]    It is, therefore, an object of the present invention to provide a cushion for a seat, in which a cover of the cushion is openable at a rear side thereof and which has a good visual appearance. 
         [0011]    It is another object of the present invention to provide a cushion for a seat, in which a pocket having a wide width is allowed to be provided. 
         [0012]    In accordance with the present invention, there is provided a cushion for a seat, including a foam padding integral with a three-dimensional cover covering the padding, the three-dimensional cover comprising a first section, a second section spaced apart from the first section and facing the first section, the second section having an opening, a peripheral section disposed between the first and second sections, extending along peripheral edges of the first and second sections, and attached at edges thereof to the peripheral edges of the first and second sections, a substantially belt-shaped piece having a width equal to a total width of the cover and provided at the second section so as to openably close the opening of the second section, a first pair of zipper tapes, one of the first pair of zipper tapes being provided along one of both side edges of the belt-shaped piece, the other of the first pair of zipper tapes being provided along a first region of the edges of the peripheral section which positionally corresponds to the one of the both side edges of the belt-shaped piece, a second pair of zipper tapes, one of the second pair of zipper tapes being provided along the other of the both side edges of the belt-shaped piece, the other of the second pair of zipper tapes being provided along a second region of the edges of the peripheral section which positionally corresponds to the other of the both side edges of the belt-shaped piece, a first slider assembly supported by the first pair of zipper tapes for zipping and unzipping the first pair of zipper tapes, and a second slider assembly supported by the second pair of zipper tapes for zipping and unzipping the second pair of zipper tapes, the opening of the second section being adapted to be closed with the belt-shaped piece at the time when the first slider assembly and the second slider assembly zip the first pair of zipper tapes and the second pair of zipper tapes, respectively, the padding being integrated with sections of the cover except the belt-shaped piece. 
         [0013]    The belt-shaped piece may be provided with a pocket which is openable along a total width of the belt-shaped piece. The second section may have folded both side edges which are sewed to regions of a peripheral edge of the peripheral section. Moreover, a longitudinal edge of the other of the first pair of zipper tapes, and a longitudinal edge of the other of the second pair of zipper tapes may be superposed on and sewed to the folded both side edges of the second section. 
         [0014]    These and other objects and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0015]      FIG. 1  is a schematic perspective view of a cover for a related art cushion, in which the cover is opened at a rear side section thereof; 
           [0016]      FIG. 2  is a sectional view showing a die apparatus for forming the related art cushion; 
           [0017]      FIG. 3  is a schematic perspective view of a seat back employing a cushion according to an embodiment of the present invention, as viewed from a rear side; 
           [0018]      FIG. 4  is a schematic perspective view of a cover for the cushion of  FIG. 3 , with a rear side section thereof being opened; 
           [0019]      FIG. 5  is a schematic fragmentary perspective view illustrating a condition where the rear side section of the cover of the cushion of  FIG. 3  is opened; 
           [0020]      FIG. 6  is a schematic fragmentary perspective view illustrating the cover in the opened-state, as viewed from an inner side of the cover; 
           [0021]      FIG. 7  is a schematic sectional view of the cushion of  FIG. 3 , taken along a line A-A in  FIG. 5 ; 
           [0022]      FIG. 8  is a schematic sectional view of the cushion of  FIG. 3 , taken along a line B-B in  FIG. 5 ; 
           [0023]      FIG. 9  is a schematic sectional view illustrating a die apparatus for forming the cushion of  FIG. 3 , in which the cover is shown in cross-section; 
           [0024]      FIG. 10  is a schematic sectional view showing the die apparatus for forming the cushion of  FIG. 3 , in which the cover is shown in vertical-section; and 
           [0025]      FIG. 11  is a schematic perspective view of a seat back employing a cushion according to another embodiment of the present invention, as viewed from a rear side. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]    Embodiments of a cushion for a seat according to the present invention, for example, embodiments of a cushion for a seat back of a vehicle seat will be discussed hereinafter with reference to  FIGS. 3 to 11 . 
         [0027]    Referring now to  FIG. 3 , there is illustrated a seat back for a vehicle seat, which employs a cushion according to an embodiment of the present invention. The cushion includes a three-dimensional cover  1  and a foam resin padding (not shown) arranged in the three-dimensional cover  1  and integrated with the three-dimensional cover  1 . 
         [0028]    Referring to  FIG. 4 , the cover  1  includes a front side section  10 , a substantially U-shaped rear side section  13  spaced apart from the front side section  10  and opposed to the front side section  10 , a peripheral section  11  disposed between the front side section  10  and the rear side section  13 , extending along peripheral edges of the front and rear side sections  10 ,  13  except lower edges of the front and rear side sections  10 ,  13 , and attached to the peripheral edges of the front and rear side sections  10 ,  13  at edges of the peripheral section  11 , and a lower side section  14  attached at an edge thereof to a lower edge of the front side section  10 . 
         [0029]    The rear side section  13  includes a pair of spaced apart side portions  17  and an upper portion  13   b  connected to upper edges of the spaced apart side portions  17  and interconnecting the spaced apart side portions  17 . The cover  1  further includes a substantially belt-shaped piece  13   a  having a width substantially equal to a total width of the cover  11 . The belt-shaped piece  13   a  is connected to the rear side section  13  with an upper edge thereof extending along a lower edge of the upper portion  13   b  of the rear side section  13  and hangs down from the lower edge of the upper portion  13   b,  whereby an opening of the U-shaped rear side section  13  is adapted to be openably closed with the belt-shaped piece  13   a.    
         [0030]    In the illustrated example, the respective sections of the cover  1  except the side portions  17  of the rear side section  13  are each formed from a piece which includes a piece of covering material such as fabric, leather, etc., and a piece of wadding material such as foamed resin laminated with the piece of covering material. On the other hand, the side portions  17  of the rear side section  13  are each formed from a resin film. 
         [0031]    As shown in  FIG. 3 , a pocket  12  is provided on the belt-shaped piece  13   a  of the cover  11 . The pocket  13  has an opening  12   a  which is openable along a substantially total width of the belt-shaped piece  13   a.    
         [0032]    Moreover, as shown in  FIG. 4 , the cover  1  further has slide fastener means which includes two pairs of zipper tapes  15   a,    15   a ′,  15   b,    15   b ′ and two slider assemblies including slider and tags (not shown). More particularly, the first zipper tape  15   a  is attached to and substantially coextensive with an edge of one of both sides of the belt-shaped piece  13   a.  A second zipper tape  15   a ′ is attached to and substantially coextensive with a first vertical edge region of the peripheral section  11  which is adjacent an outer edge of the one of the side portions  17  of the rear side section  13 . A first slider assembly (not shown), supported by the first zipper tape  15   a  and the second zipper tape  15   a ′, is included for zipping and unzipping the first zipper tape  15   a  with respect to the second zipper tape  15   a ′. Also, a third zipper tape  15   b  is attached to and substantially coextensive with an edge of the other of the both side of the belt-shaped piece  13   a.  A fourth zipper tape  15   b ′ is attached to and substantially coextensive with a second vertical edge region of the peripheral section  11  which is adjacent an outer edge of the other of the side portions  17  of the rear side section  13 . A second slider assembly (not shown), supported by the third zipper  15   b  and the fourth zipper tape  15   b ′, is included for zipping and unzipping the third zipper tape  15   b  with respect to the fourth zipper tape  15   b ′. The first slider assembly and the second slider assembly are slid upward along the first and second zipper tapes  15   a,    15   a ′ and the third and fourth zipper tapes  15   b,    15   b ′, respectively, whereby the zipper tapes  15   a,    15   a ′,  15   b,    15   b ′ are unzipped, the belt-shaped piece  13   a  is separated from the peripheral section  11  of the cover  1  and the opening of the rear side section  13  is brought into a condition where it is allowed to be opened. On the other hand, the first slider assembly and the second slider assembly are slid downward along the first and second zipper tapes  15   a,    15   a ′ and the third and fourth zipper tapes  15   b,    15   b ′, respectively, whereby the zipper tapes  15   a,    15   a ′,  15   b,    15   b ′ are zipped, the belt-shaped piece  13   a  is separatably coupled to the peripheral section  11  of the cover  1  and the opening of the rear side section  13  is closed with the belt-shaped piece  13   a.    
         [0033]    The belt-shaped piece  13   a  has an engaging fastener  18  of a substantially J-shape in cross-section attached to a lower edge thereof. The lower side section  14  of the cover  1  has an engaging fastener  19  of a plate shape attached to an edge of a free end thereof. The engaging fastener  18  and the engaging fastener  19  are adapted to be disengageably engaged with each other. 
         [0034]    The foam resin padding which is to be integrated with the three-dimensional cover  1  is integrated with the respective sections of the cover  1  except the belt-shaped piece  13   a  and the lower side section  14  of the cover  1 , by a die apparatus which will be discussed hereinafter. A cavity for receiving a frame for the cushion therein is formed in a rear section of the padding by a core of the die apparatus as will be discussed hereinafter. 
         [0035]    The both side portions  17  of the rear side section  13  have lengths which allow the both side portions  17  to cover or conceal, from the inner side, the entire edge of the belt-shaped piece  13   a  to which the first zipper tape  15   a  is attached, the entire vertical edge region of the peripheral section  11  to which the second zipper tape  15   a ′ is attached, the entire edge of the belt-shaped piece  13   a  to which the third zipper tape  15   b  is attached, and the entire vertical edge region of the peripheral section  11  to which the fourth zipper tape  15   b ′ is attached. 
         [0036]    Referring to  FIGS. 5 and 6 , upper end portions of the first and second zipper tapes  15   a,    15   a ′ (and upper end portions of the third and fourth zipper tapes  15   b,    15   b ′) are disposed downward of an upper edge  17   a  of a corresponding side portion  17  of the rear side section  13 . While a space is easy to be produced between the upper end portions of the first and second zipper tapes  15   a,    15   a ′ (and the third and fourth zipper tapes  15   b,    15   b ′), the upper end portions of the zipper tapes are adapted to be completely covered or concealed by the corresponding side portion  17  of the rear side section  13  from the inner side. Incidentally, upper edges of the first and second zipper tapes  15   a,    15   a ′ (and the third and fourth zipper tapes  15   b,    15   b ′) and the upper edge  17   a  of the corresponding side portion  17  of the rear side section  13  may be disposed in the substantially same level. 
         [0037]    In the illustrated example, as shown in  FIGS. 7 and 8 , a longitudinal edge portion of the second zipper tape  15   a ′ (and a longitudinal edge portion of the fourth zipper tape  15   b ′) is superposed on an outer surface of the first vertical edge region (and an outer surface of the second vertical edge region) of the peripheral section  11  and a folded outer edge portion of the corresponding side portion  17  is superposed on an inner surface of the first vertical edge region (and an inner surface of the second vertical edge region) of the peripheral section  11 . The longitudinal edge portion of the second zipper tape  15   a ′ (and the longitudinal edge portion of the fourth zipper tape  15   b ′), the first vertical edge region (and the second vertical edge region) of the peripheral section  11 , and the folded outer edge portion of the corresponding side portion  17  are sewed together. Moreover, the first and third zipper tapes  15   a,    15   b  are sewed at longitudinal edge portions thereof to the both vertical edge portions of the belt-shaped piece  13   a  with the longitudinal edge portions thereof being arranged outer surfaces of the edge portions of the belt-shaped piece  13   a.  Thus, when the zipper tapes  15   a,    15   a ′ are engaged with each other and the zipper tapes  15   b,    15   b ′ are also engaged with each other, a sewed region  17   b  which is formed by causing the longitudinal edge portion of the second zipper tape  15   a ′ (and the longitudinal edge portion of the fourth zipper tape  15   b ′), the first vertical edge region (and the second vertical edge region) of the peripheral section  11 , and the folded outer edge portion of the corresponding side portion  17  to be sewed together, and a sewed region  13   b  which is formed by causing the longitudinal edge portions of the zipper tapes  15   a,    15   b  and the both edge portions of the belt-shaped piece  13   a  to be sewed together are covered or concealed as shown in  FIG. 8 . As shown in  FIGS. 5 ,  6  and  8 , a substantially rectangle-shaped sheet  117  of resin is disposed on the upper end portions of the first and second zipper tapes  15   a,    15   a ′ (and the third and fourth zipper tapes  15   b,    15   b ′). The resin sheet  117  serves as means to conceal a slider  15   c  and a tag  15   d  of a corresponding slider assembly from the inner side and conceal a space between upper parts of the sewed regions  13   b,    17   b  from the outer side, when the slider  15   c  is slid along the zipper tapes  15   a,    15   a ′ (or the zipper tapes  15   b,    15   b ′), arrives at the upper end portions of the zipper tapes  15   a,    15   a ′ (or the zipper tapes  15   b,    15   b ′) and the zipper tapes are completely unzipped. 
         [0038]    The resin sheet  117  is provided in such a manner that an upper edge  117   e  thereof ( FIG. 5 ) is located upward of the slider  15   c  arriving at the upper end portions of the zipper tapes. The resin sheet  117  is sewed at both edges thereof to the sewed regions  13   b,    17   b  so as to straddle the edge region of the peripheral section  11  and a corresponding edge portion of the belt-shaped piece  13   a.    
         [0039]    Incidentally, in the illustrated embodiment, as shown in  FIGS. 7 and 8 , an entire surface of the cavity  5   a  for receiving the frame for the cushion therein, which is formed in the rear section of the padding  5  by the core of the die apparatus as will be discussed hereinafter, is adapted to be covered with a sheet  5   b  of backing material which is attached onto the entire surface of the cavity  5   a  of the padding  5  by the die apparatus. The backing sheet  5   b  serves as means to prevent the padding  5  from being rubbed directly against the frame at the time of inserting operation of the frame into the cavity  5   a  of a finished seat. The backing sheet is formed from a sheet of non-woven fabric or the like. 
         [0040]    The cushion for the seat back, which is constructed as discussed above, may be produced by, for example, a die apparatus  2  which is shown in  FIGS. 9 and 10 . 
         [0041]    The die apparatus  2  includes a first die means  20  for forming front and rear sections and a peripheral section of the cushion, a core  21  for forming the cavity  5   a  opened in the rear section of the foam padding  5  and causing the backing sheet  5   b  to cover the cavity, and a second die means  22  adapted to be combined with the first die means  20  and clamped against the first die means  20  when the cushion is to be formed by the die apparatus. At the forming of the cushion, the cover  1  is to be laid on the first die means  20 . 
         [0042]    While  FIG. 9  shows only half of the die apparatus  2 , the die apparatus  2  has a geometric symmetry structure. Incidentally, in the event that an air-permeable cover is employed as the cover  1 , the first die means  20  on which the cover  1  is to be laid preferably has air-ventilating holes (not shown). In this case, a vacuum pump means (not shown) for providing a vacuum is coupled to the air-ventilating holes through paths. When the vacuum is applied to the first die means  20  by the vacuum pump means, the vacuum is applied through the air-ventilating holes to the cover  1  on the first die means  20 , to thereby cause the cover  1  to be drawn onto and set on the first die means  20 . 
         [0043]    As shown in  FIG. 9 , the first die means  20  is provided with a first sectional die means  23  for forming the rear section of the cushion, and a second sectional die means  24  for forming the peripheral section of the cushion. The first sectional die means  23  is coupled to the second sectional die means  24  by a first hinge means  25   a.  The second sectional die means  24  is coupled to the first die means  20  by a second hinge means  25   b.  Thus, the first and second sectional die means  23 ,  24  can be opened and closed with respect to the first die means  20  by the first and second hinge means  25   a,    25   b.    
         [0044]    When the die apparatus  2  is to form the cushion, the first sectional die means  23  is adapted to be contacted with the side portions  17  of the rear side section of the cover  1  (laid on the first die means  20 ) at a die surface  23   a  thereof. The first sectional die means  23  has an inner slant surface  23   b  which is to face a slant surface  22   a  of the second die means  22 . 
         [0045]    The core  21  includes a first section  21   a  and a second section  21   b  which are dividable. The first section  21   a  of the core  21  is provided with a protrusion  21   c  which is to face the die surface  23   a  of the first sectional die means  23 , and a slant surface  21   d  which extends from the protrusion  21   c  and is to face the slant surface  22   a  of the second die means  22 . When the die apparatus  2  is to form the cushion, the side portions  17  of the rear side section  13  of the cover  1  are interposed between the die surface  23   a  of the first sectional die means  23  and the protrusion  21   c  of the core  21  with free edge portions of the side portions  17  of the rear side section  13  being received within a first spaces  26  which is defined by the inner slant surface  23   b  of the first sectional die means  23 , the slant surface  22   a  of the second die means  22 , the slant surface  21   d  of the first section  21   a  of the core  21 , and the protrusion  21   c  of the first section  21   a  of the core  21 . 
         [0046]    As shown in  FIG. 10 , the first die means  20  is further provided with a third sectional die means  27  which is to be contacted with the upper portion  13   b  of the rear side section  13  of the cover  1 . The third sectional die means  27  is coupled to the first die means  20  by a third hinge means  25   c  so as to be openable and closable with respect to the first die means  20 . The third sectional die means  27  has a planar surface  27   a  which is to face the protrusion  21   c  of the first section  21   a  of the core  21 , and an inner surface  27   b  which is to face the slant surface  22   a  of the second die means  22 . The upper portion  13   b  of the rear side section  13  is interposed between the planar surface  27   a  of the third sectional die means  27  and the protrusion  21   c  of the first section  21   a  of the core  21 . 
         [0047]    The second die mean  22  has a pouring hole  22   b  for allowing expandable resin to be poured into the die apparatus  2  therethrough. Arranged tangentially with an end of the second section  21   b  of the core  21  is a hold-down sectional die means  21   e  of a plate-shape for holding against the first die means  20  a boundary between the lower side section  14  and the front side section  10  of the cover  1 . The hold-down sectional die means  21   e  has a notch  21   f  for allowing the expandable resin from the pouring hole  22   b  of the second die means  22  to flow into the cover  1 . The notch  21   f  of the hold-down sectional die means  21   e  communicates with the pouring hole  22   b  of the second die means  22  through a hole  21   b ′ formed in the second section  21   b  of the core  21 . Two pipes  21   g  (only one pipe  21   g  is shown in  FIG. 10 ) for forming through-holes in the padding  5  for receiving stays of a head rest are arranged in close proximity to the first section  21   a  of the core  21  and aligned with through-holes  11   a  (see  FIGS. 3 and 4 ) of the cover  1 . 
         [0048]    A second space  28   a  is defined between the second die means  22  and the third sectional die means  27 . Through the second space  28   a,  the belt-shaped piece  13   a  of the cover  1  can be drawn out of the die apparatus  2 . Further, a third space  28   b  is defined between the first die means  20  and the second die means  22 . The lower section  14  of the cover  1  is received in the third space  28   b.    
         [0049]    The die apparatus  2  is further provided with two cylinders  29  having positioning pins  29   a  which are adapted operatively penetrate the through-holes  11   a  ( FIGS. 3 and 4 ) of the cover  1  and fit into the pipes  21   g.    
         [0050]    Again referring to  FIGS. 9 and 10 , the forming of the cushion which is performed utilizing the die apparatus of  FIGS. 9 and 10  will be discussed hereinafter. 
         [0051]    In a condition where the second die means  22  is removed from the first die means  20  and the first, second and third sectional die means  23 ,  24 ,  27  are opened with respect to the first die means  20  by the hinge means  25   a,    25   b,    25   c,  the cover  1  is laid on a die surface of the first die means  20  with the belt-shaped piece  13   a  being separated from the peripheral section  11  of the cover  1  by unzipping the first and third zipper tapes  15   a,    15   b  of the belt-shaped piece  13   a  from the second and fourth zipper tapes  15   a ′,  15   b ′. In the condition where the cover  1  is set on the die surface of the first die means  20 , the hold-down sectional die means  21   e  is combined with the first die means so as to be put on the boundary between the front side section  10  and the lower side section  14  against the first die means  20 , the core  21  is inserted into the three-dimensional cover  1 , with the backing sheet  5   a  being wound at an end portion thereof around the first section  21   a  of the core  21  and extending along bottom surfaces of the first and second sections  21   a,    21   b  of the core  21 . Moreover, the pipes  21   g  are arranged between the first section  21   a  of the core  21  and a top portion of the peripheral section  11  of the cover  11 , and the positioning pins  29   a  of the cylinders  29  are operatively fitted into the pipes  21   g.  Thereafter, the first, second and third sectional die means  23 ,  24 ,  27  are closed with respect to the first die means  20  and clamped against the first die means  20 . The second die means  22  is then combined with the first die means  20  and clamped against the first die means  20  in a condition where the free edge portions of the side portions  17  of the rear side section  13  of the cover  1  are received within the first space  26 , the belt-shaped piece  13   a  of the cover  1  is drawn out of the die apparatus  2  through the second space  28   a,  and the lower section  14  of the cover  1  is received within the third space  28   b.  In this condition, the expandable resin is poured into the interior of the cover  1  through the pouring hole  22   b  of the second die means  22 , the hole  21   b ′ of the core  21  and the notch  21   f  of the hold-down sectional die means  21   e,  and foams in the interior of the cover  1 , whereby a cushion in which the padding  5  of the foaming resin is integrated with the cover  1  and the backing sheet  5   b  and formed with the cavity  5   a  for receiving the seat back frame is formed. 
         [0052]    In the die apparatus  2 , the upper portion  13   b  of the rear side section  13  of the cover  1  is interposed between the die surfaces  23   a,    27   a  of the first and third sectional die means  23 ,  27  and the protrusion  21   c  of the core  21 , and the boundary between the front side section  10  and the lower side section  14  is interposed between the die surface of the first die means  20  and the hold-down sectional die means  21   e.  Therefore, a portion of the foaming resin is prevented from being impregnated into the belt-shaped piece  13   a  and the lower side section  14  of the cover  1 . Thus, the finished cushion which exhibits an appropriate cushioning property and a good touch feeling property can be obtained. 
         [0053]    After the finished cushion which is formed in the manner as discussed above is removed from the die apparatus, the seat back frame is incorporated into the cavity  5   a  of the padding  5  of the cushion in the condition where the zipper tapes  15   a,    15   a ′,  15   b,    15   b ′ remain unzipped and the rear side section  13  of the cover  1  is opened by the belt-shaped piece  13   a  separated from the peripheral section  11  due to the unzipping of the zipper tapes. More particularly, as shown in  FIG. 3 , the seat back frame is incorporated into the cavity  5   a  of the padding  5  ( FIGS. 9 and 10 ) of the cushion with side brackets  4   a,    4   b  thereof projecting out of the cover  1 . Then, the belt-shaped piece  13  is coupled to the peripheral section  11  of the cover  1  by zipping the first and third zipper tapes  15   a,    15   b  with respect to the second and fourth zipper tapes  15   a ′,  15   b ′, to thereby conceal the opening of the rear side section  13  of the cover  1  with the belt-shaped piece  13 . 
         [0054]    In the cushion for the seat, which is constructed as discussed above, while the first and third zipper tapes  15   a,    15   b  are sewed to the edges of the belt-shaped piece  13   a,  and the second and fourth zipper tapes  15   a ′,  15   b ′ are sewed to the vertical edge regions of the peripheral section  11  of the cover  1 , the sewed portion  13   b  between the first zipper tape  15   a  (and the third zipper tape  15   b ) and the edge of the belt-shaped piece  13   a,  and the sewed portion  17   b  between the second zipper tape  15   a ′ (and the fourth zipper tape  15   b ′) and the vertical edge region of the peripheral section  11  are concealed inside the zipper tapes as shown in  FIG. 8 . Thus, the cushion having a good visual appearance can be obtained. 
         [0055]    Moreover, the belt-shaped piece  13   a  has the width equal to the total width of the cover  1 , so that the pocket  12  having a wide width can be provided on the belt-shaped piece  13   a  as shown in  FIG. 3 . 
         [0056]    In addition, when the cushion is to be formed, the second and fourth zipper tapes  15   a ′,  15   b ′ are insulated through the side portions  17  of the rear side section of the cover  1  from the expandable resin poured into the interior of the cover  1  as shown in  FIG. 9 , so that the expandable resin does not adhere to the second and fourth zipper tapes  15   a ′,  15   b ′. Moreover, the rectangle-shaped resin piece  117  straddles the upper end portions of the first and second zipper tapes  15   a,    15   a ′ (and the third and fourth zipper tapes  15   b,    15   b ′), to which the slider  15   c  with the tag  15   d  is slid, and protects an upper part of the vertical edge region of the peripheral section  11  and an upper part of the vertical edge portion of the side portion  17  of the rear side section  13 . Therefore, there is no possibility that a jointed region between the upper part of the vertical edge region of the peripheral section  11  and the upper part of the vertical edge portion of the side portion  17  will be broken, and the expandable resin can be prevented from adhering to the slider  15   c  and the tag  15   d.    
         [0057]    Moreover, the vertical edge portions of the side portions  17  of the rear side section  13  are folded and sewed to the vertical edge regions of the peripheral section  11 , so that strength of the sewed portions  17   b  of the cover  1  is ensured. Incidentally, the side portions  17  of the rear side section  13  may be formed of flexible material. In this case, operability of sewing the side portions  17  to the peripheral section  11  and operability of causing the cover  1  to be laid on the first die means can be improved, thus making it possible to easily produce the cushion. 
         [0058]    Incidentally, while the case where the present invention is applied to the cushion provided with the pocket has been discussed above with reference to the embodiment of the present invention, the present invention may be applied to a cushion which is not provided with any pocket as shown in  FIG. 11 . Moreover, the zipper tapes  15   a,    15   a ′,  15   b,    15   b ′ may be designed such that they are exposed on the both edges of the belt-shaped piece  13   a  in the condition where the zipper tapes  15   a,    15   a ′,  15   b,    15   b ′ are zipped. In addition, while the case where the present invention is applied to the cushion for the seat back of the vehicle seat has been discussed above with reference to the embodiment of the present invention, the present invention may be also applied to a cushion for a seat cushion of a vehicle seat. 
         [0059]    The terms and expressions which have been employed herein are used as terms of description and not of limitation. There is no intention in the use of such terms and expressions to exclude any equivalents of the features shown and described, or any portion thereof. It is recognized, however, that various modifications are possible within the scope of the invention claimed.