Ball for ball game and method for manufacturing ball for ball game

Technical Field

The present invention relates to a ball for a ball game and a method for manufacturing the ball for a ball game.

Background Art

A ball for a ball game including a bladder, a fabric layer positioned on the outer side of the bladder, and a skin layer located on the outer side of the fabric layer and constituted by a plurality of panels is known, as disclosed in EP 1578504 B1. As depicted in FIG. 14, a fabric layer 63, which is also referred to as a sewn carcass, is constituted by a plurality of fabric pieces 66. Each fabric piece 66 is formed, for example, as a pentagon, and a circumferential edge portion 66a of the fabric piece 66 is sewn to the circumferential edge portion 66a of the adjacent fabric piece 66 with a thread 72. The fabric layer 63 is formed into a spherical shell shape by sewing together the plurality of fabric pieces 66.

The circumferential edge portion 66a of the fabric piece 66 is superimposed on the circumferential edge portion 66a of the adjacent fabric piece 66, and the two are sewn together with the thread 72. Therefore, when the plurality of fabric pieces 66 which have been sewn together are formed into a spherical shell shape, the circumferential edge portion 66a of each fabric piece 66 is folded. The fabric layer 63 is reversed such that when the bladder 62 is inserted, the circumferential edge portion 66a of each fabric piece 66 is folded inward. Therefore, as depicted in FIG. 15

, as a result of the circumferential edge portion 66a of the fabric piece 66 being pushed from the inside by the outer surface of the bladder 62, the circumferential edge portion is folded, for example, to one side, the folding starting from the portion sewn with the thread 72.

In the configuration in which the circumferential edge portion 66a of the fabric piece 66 is folded, a groove 68 with a V-shaped cross section appears in the region where the circumferential edge portions 66a of the adjacent fabric pieces 66 are in contact with each other. Panels 64 forming the skin layer 65 are bonded to the fabric layer 63, but in the portion where the groove 68 has been formed, a gap appears between the fabric layer 63 and the panel 64. Due to the presence of the gap, the panel 64 can easily peel off from the fabric layer 63. Further, because a region 64a of the panel 64 forming the skin layer 65, this region being positioned above the groove 68, sinks due to the presence of the gap, a stripe-like pattern is formed on the outer surface of the panel 64. Such a phenomenon also occurs in the so-called stitched ball in which a plurality of panels 64 forming the skin layer 65 are sewn together.

US 2 091 455 A relates to methods and means for constructing inflated leather balls particularly basket balls, volley balls, soccer balls and the like.

Summary of Invention

It is an objective of the present invention to provide a ball for a ball game having a fabric layer configured by sewing together a plurality of fabric pieces, in which a stripe-like pattern is prevented from forming on the outer surface of a skin layer.

A ball for a ball game according to an aspect of the present invention is defined in claim 1.

A method for manufacturing the ball for a ball game according to another aspect of the present invention is defined in claim 8.

Brief Description of Drawings

• FIG. 1 illustrates the external appearance of a ball for a ball game according to a first embodiment of the present invention;
• FIG. 2 is a cross-sectional view taken along the II-II line in FIG. 1;
• FIG. 3 depicts a fabric piece used in the ball for a ball game;
• FIG. 4 is a partial view of a fabric body in a state in which the circumferential edge portion of the fabric piece is folded inward;
• FIG. 5 illustrates a state in which a tape material is attached to the fabric body;
• FIG. 6 illustrates a state in which the fabric body is set into a mold;
• FIG. 7 illustrates a method for manufacturing a ball for a ball game according to another embodiment;
• FIG. 8 relates to a ball for a ball game according to a second embodiment of the present invention and corresponds to FIG. 2;
• FIG. 9A is a side view of a fabric body used in a ball for a ball game according to a third embodiment of the present invention;
• FIG. 9B is a front view of the fabric body used in the ball for a ball game according to the third embodiment of the present invention;
• FIG. 10 is a front view of a fabric body used in a ball for a ball game according to a modification of the third embodiment of the present invention;
• FIG. 11 is a view illustrating attachment positions of skin panels in a ball for a ball game using the fabric body shown in FIG. 10;
• FIG. 12 is a partial cross-sectional view of the ball for a ball game using the fabric body shown in FIG. 10;
• FIG. 13 is a partial cross-sectional view of a ball for a ball game according to another modification;
• FIG. 14 illustrates the fabric layer of the conventional ball for a ball game; and
• FIG. 15 is a cross-sectional view of the conventional ball for a ball game.

Description of Embodiments

Embodiments of the present invention will be explained below in greater detail with reference to the appended drawings.

FIG. 1 illustrates the external appearance of a ball for a ball game according to an embodiment (first embodiment) of the present invention. As depicted in the figure, the ball for a ball game of the present embodiment is configured as a soccer ball. The present soccer ball is provided with a plurality of skin panels 4. The skin panels 4 can be of a pentagonal shape (12 panels) and a hexagonal shape (20 panels). The ball may be also configured by 12 pentagons. A configuration in which a spherical surface is covered with a plurality of panels 4 of other shape can be also used. A valve hole 1 used to pump the air is provided in one of the skin panels 4.

As depicted in FIG. 2, the present soccer ball includes a bladder 2 of a hollow shape, a fabric layer 3 provided on the outer side of the bladder 2, and a skin layer 5 provided on the outer side of the fabric layer 3. The bladder 2 is configured in a hollows shape by using an air-impermeable rubber such as a butyl rubber or a latex rubber. Compressed air is sealed in the bladder 2. The bladder 2 is also provided with a valve house (valve holding section) (not shown in the figure) that holds a valve for introducing the compressed air.

The fabric layer 3 serves as a reinforcing layer that reinforces the bladder 2. The fabric layer 3 has a plurality of fabric pieces. In the present embodiment, a total of 12 fabric pieces 6 formed in a pentagonal shape are provided. The fabric layer 3 is formed in a spherical shell shape by sewing together the fabric pieces 6. Each side of the fabric piece 6 has a curvilinear, rather than linear, shape obtained by slight curving such that bulges outward (see FIG. 3) so as to obtain a spherical shell when the fabric pieces 6 are sewn together. The circumferential edge portion 6a of the fabric piece 6 serves as a seam allowance which is folded when this fabric piece is sewn together with another fabric piece 6.

Cotton, blends of cotton and polyesters, and cloth from high-strength fibers can be used as a material for the fabric pieces 6. The fabric pieces 6 may be also obtained by laminating a plurality of fabric sheets. In this case, it is preferable that the warp and weft of a plurality of fabric sheets be orthogonal such that the tensile strength in the longitudinal direction of the laminated fabric pieces be equal to the tensile strength in the transverse direction.

The adjacent fabric pieces 6 are sewn together and the circumferential edge portions 6a of the fabric pieces 6 are therefore folded inward (bladder 2 side) from the body of the fabric pieces 6, as shown in FIG. 2. Therefore, the groove 8 is formed on the outer side (upper side) of the region where the outer surfaces of the circumferential edge portions 6a are in contact with each other. Thus, in the fabric layer 3, the grooves 8 concaved inward are formed along the outer circumferential portions of the fabric pieces 6.

The groove 8 is filled with a filler 10. The filler 10 is formed such as to fill the groove 8. Therefore, the outer surface of the filler 10 is linked smoothly from the outer surface of the fabric layer 3. As a result, the recesses on the surface of the fabric layer 3 in the outer peripheral portion of the fabric pieces 6 are eliminated, and the fabric layer 3 and the filler 10 have as a whole a curved surface (spherical surface).

The filler 10 is formed of a vulcanized rubber. Therefore, part of the filler 10 penetrates between the fibers constituting the fabric pieces 6, thereby fixedly attaching the filler to the fabric pieces 6. The filler 10 also penetrates into the gaps between the fibers constituting the fabric pieces 6 and the sewing threads 12. Therefore, the filler 10 reinforces the sewing regions of the fabric pieces 6. A natural rubber or a synthetic rubber, for example, can be used as a rubber material constituting the filler 10.

The skin layer 5 is provided with the plurality of skin panels 4. Each skin panel 4 has a skin material 4c and a rear surface member 4d attached to the rear side of the skin material 4c. The skin material 4c is provided over the front-side surface 4a of the skin panel 4 and a side surface 4b extending along the outer circumferential portion of the front-side surface 4a. The front-side surface 4a is a spherical surface serving as the outer surface of a ball for a ball game. The side surface 4b enters the interior from the spherical front-side surface 4a. Thus, the skin material 4c is bent along the shape of the rear surface member 4d. As a result, the front-side surface 4a and the side surface 4b of the skin panel 4 are formed of the skin material 4c, and the rear surface member 4d is present on the rear-side surface of the skin panel 4.

Artificial leather, synthetic leather, thermoplastic urethane resins (TPU), and rubbers can be used for the skin material 4c. The artificial leather is configured by coating a urethane resin (PU) with a thickness of about 0.1 mm on the uppermost layer and attaching a nonwoven or woven fabric layer as the lower layer. The synthetic leather is configured by attaching a fabric layer to soft PVC. A configuration obtained by attaching a woven fabric to a rubber sheet with a thickness of 0.6 mm to 1.2 mm can be used as the rubber. In the case of artificial leather, synthetic leather, and rubber, the upper layer is attached to the rear surface member 4d, with the nonwoven or woven fabric layer, which is a lower layer, being interposed therebetween. In the case of TPU, the upper layer is directly attached to the rear surface member 4d. The thickness of the skin material 4c is desirably 0.1 mm to 1.5 mm. The rear surface member 4d plays a role of an impact absorbing member and is configured by a buffering member from woven fabric, nonwoven fabric, or a foamed material such as EVA, SBR, EPDM, polyethylene, polyurethane, chloroprene, and neoprene.

The rear surface member 4d is provided in the interior surrounded by the skin material 4c. In other words, the thickness of the skin panel 4 is regulated by the rear surface member 4d. Each skin panel 4 is configured to have a thickness of 1.0 mm (inclusive) to 8 mm (inclusive), preferably 1.5 mm (inclusive) to 5 mm (inclusive).

The lower surface of each skin panel 4 is bonded by an adhesive 14 to the fabric layer 3 and the filler 10. Thus, the filler 10 is provided in a linear shape extending along the outer periphery of the fabric pieces 6. That is, the filler 10 is disposed such as to follow the outer periphery of the fabric pieces 6 indicated by a broken line in FIG. 1. In other words, the filler 10 is provided on the stitching line obtained by sewing together the fabric pieces 6. Therefore, the filler 10 includes a region P1 which crosses the region where the side surfaces 4b of the adjacent skin panels 4 are in contact with each other, and a region P2 present directly below the intermediate position of the skin panels 4. Concerning the rear surface member 4d which is not in contact with the filler 10, as shown in FIG. 2, the lower surface of the rear surface member 4d is bonded to the fabric layer 3. Meanwhile, in the skin panel 4 positioned above the filler 10, the rear surface member 4d is bonded to the fabric layer 3 and the filler 10. A stripe-like pattern in which the surface of the skin panel 4 sinks does not appear in this region. In the region where the side surfaces 4b of the adjacent skin panels 4 are in contact with each other, the skin material 4c is also bonded to the filler 10. In other regions, the skin material 4c is bonded to the fabric layer 3.

A chloroprene adhesive, latex and a urethane adhesive can be used as the adhesive 14 that bonds the skin panels 4 to the fabric layer 3.

The skin panel 4 does not necessarily have the configuration in which the skin material 4c is bent along the shape of the rear surface member 4d. Thus, as a result of cutting the circumferential edge portion of the skin panel 4 obliquely so that it becomes thinner toward the end thereof, the circumferential edge portion of the skin panel 4 may be shaped to decrease gradually in thickness. Also in this case, the V-shaped groove 8 is formed on the outer side (upper side) of the fabric layer 3 at the region where the outer surfaces of the adjacent circumferential edge portions 6a are in contact with each other. Therefore, it is necessary to fill the groove 8 with the filler 10 to prevent formation of a pattern extending along the groove 8 on the surface of the skin panel 4. Accordingly, the filler 10 is filled in the groove 8 on the fabric layer 3 to thereby prevent the formation of the pattern extending along the groove 8 on the skin layer 5.

A method for manufacturing the ball for a ball game of the present embodiment is explained below.

Initially, a step of forming the fabric layer 3 is explained. In this formation step, a fabric body of a spherical shell shape is formed by sewing together the fabric pieces 6. More specifically, initially, in a state in which two pentagonal fabric pieces 6 are overlapped, pentagon sides are sewn together with the sewing thread 12 along the broken line L shown in FIG. 3. As a result two adjacent fabric pieces 6 are sewn together. Then, another fabric piece 6 adjacent to those two fabric pieces 6 is sewn together along the adjacent sides thereof. A fabric body of a spherical shell shape can thus be formed by repeating the above-described operation with respect to 12 pentagonal fabric pieces 6. In this case, one side of any one fabric piece 6 is not sewn and left as an opening. When the fabric pieces 6 are sewn together, all of the seam allowances (circumferential edge portions 6a) are bent outward. Therefore, the fabric body of a spherical shell shape is reversed before the very last seam allowance is sewn. Thus, in a state in which one side is open, the spherical shell body is reversed using this opening (spherical shell formation step). As a result, as shown in FIG. 4, the seam allowances (circumferential edge portions 6a) of the fabric pieces 6 that have been sewn together are bent inward of the spherical shell body.

The bladder 2 is then accommodated inside the fabric body. Since a hole (not shown in the figure) for valve insertion is provided in the fabric body, the valve holding portion of the bladder 2 is aligned with this hole, and the periphery of the valve house (valve holding portion) is bonded to the fabric layer 3. The very last seam allowance (circumferential edge portion 6a) where the opening has been formed is then turned inward of the spherical sheet body and sewn from the outside, thereby closing the opening of the fabric body. As a result, a ball base body is formed on the outer side of the bladder 2, the ball base body having the fabric layer 3 formed such that all of the circumferential edge portions 6a are bent inward (base body formation step). As a consequence, grooves 8 are formed in the locations corresponding to the seam allowances (circumferential edge portions 6a) on the outer surface of the fabric layer 3.

Then, as shown in FIG. 5, the elongated tape material 20 is attached to the outer surface of the fabric layer 3 along the groove 8 formed in the fabric layer 3 (tape attachment step). As mentioned hereinabove, since the grooves 8 are formed on the outer side of the region where the outer surfaces of the circumferential edge portions 6a are in contact with each other in the fabric layer 3, the elongated tape material 20 is disposed such as to cover the groove 8. Since the tape material 20 is formed from an unvulcanized rubber, it is bonded due to the adhesivity thereof to the fabric piece 6.

Then, as depicted in FIG. 6, the fabric layer 3 in which the bladder 2 is accommodated and to which the tape material 20 is attached is set into a mold 22, air is pumped into the bladder 2 and pressurized, and the mold 22 is heated in this state. As a result, the tape material 20 is vulcanized. In this case, the tape material 20 changes the shape thereof, penetrates into the groove 8 of the fabric layer 3, fills the groove 8 and becomes the filler 10 (filling step). At this time, the rubber constituting the tape material 20 also penetrates into the gaps between the fibers constituting the fabric layer 3 and into the gaps between the fibers and the sewing thread 12. As a result, a state is assumed in which the groove 8 is filled with the filler 10 which is fixedly attached to the fabric layer 3, and the sewing region obtained with the sewing thread 12 is reinforced.

The ball base body is removed from the mold 22 and the adhesive 14 is coated on the surface of the ball base body (coating step). Then, a plurality of skin panels 4is arranged, without a gap therebetween, on the ball base body and the adhesive 14 is dried (skin layer 5 formation step). As a result, a state is obtained in which the skin panels 4 are bonded to the fabric layer 3, and the production of the ball for a ball game is completed.

As mentioned hereinabove, in the present embodiment, since the groove 8 formed on a region where the circumferential edge portions 6a of the mutually adjacent fabric pieces 6 are in contact with each other is filled with the filler 10, no gap is present between the skin layer 5 and the fabric layer 3 even in the location of the groove 8. Therefore, the region of the skin panel 4 that is positioned on the groove 8 does not sink into the groove 8. As a consequence, the formation of a stripe-like pattern on the outer surface of the skin layer 5 can be prevented. Furthermore, since the skin layer 5 is bonded not only to the fabric layer 3, but also to the filler 10, peeling of the skin layer 5 can be suppressed. In addition, since the filler 10 is formed of a vulcanized rubber, the filler 10 can be fixedly attached to the fabric layer 3 during the vulcanization. Further, since the fabric layer 3 is configured by sewing together a plurality of fabric pieces 6, a ball for a ball game which is soft to touch can be obtained.

In the manufacturing method of the present embodiment, the tape material 20 formed of an unvulcanized rubber is attached to the fabric layer 3 so as to cover the groove 8 of the fabric layer 3, and the groove 8 is filled with the filler 10 by heating the tape material. In this case, the tape material 20 is melted and heated while changing the shape thereof so as to match the shape of the groove 8. Part of the rubber penetrates into the gaps between the fibers of the fabric pieces 6 and also into the gaps between the fibers and the sewing thread 12. As a result, the filler 10 is fixedly attached to the fabric pieces 6. During the vulcanization, the tape material 20 is pressed against a spherical inner cavity surface 22a of the mold 22. Therefore, the tape material 20 is deformed into a shape having the outer surface matching the outer surface of the substantially spherical fabric layer 3 during the vulcanization. As a consequence, the filler 10 can be formed without using a member that has been shaped in advance to match the shape of the groove 8.

The present invention is not limited to the embodiment and can be variously changed and modified without departing from the scope thereof. For example, the manufacturing method of the present embodiment includes the tape attachment step of attaching the elongated tape material 20 to the outer surface of the fabric layer 3 along the groove 8 formed in the fabric layer 3. Instead of such manufacturing method, the tape material 20 may be provided between the fabric pieces 6 in the step of forming the fabric layer 3. More specifically, as shown in FIG. 7, when the fabric pieces 6 are sewn together with the sewing thread 12, the tape material 20 is sandwiched in between the circumferential edge portions 6a of the fabric pieces 6 and the tape material 20 is sewn together with the circumferential edge portions 6a. In this case, part of the tape material 20 is disposed such as to protrude to the front side (outer surface side) of the fabric pieces 6. The bladder 2 is then accommodated inside the fabric body of a spherical shell shape, the opening of the fabric body is closed, and the ball base body is formed. The tape material 20 is then vulcanized by setting the ball base body in the mold 22. At this time, the circumferential edge portion 6a of one of the adjacent fabric pieces 6 is bonded to the circumferential edge portion 6a of the other of the adjacent fabric pieces 6 by the rubber material constituting the tape material 20. Therefore, the filler 10 also fills the gap between the one and the other circumferential edge portions 6a. This allows the seam of the adjacent fabric pieces 6 to be further reinforced. With such a method the ball for a ball game depicted in FIG. 2 can be obtained. This method makes it possible to omit the step of attaching the tape material 20 to the outer surface of the fabric layer 3. Further, the filler 10 can be also effectively loaded into the regions of the fabric pieces 6 that are sewn together with the sewing thread 12.

The ball for a ball game of the first embodiment is the-so-called laminated ball in which the skin layer 5 is bonded to the fabric layer 3 with an adhesive. By contrast, the ball for a ball game of the second embodiment is a stitched ball (i.e., machine sewing ball or hand stitched ball).

As depicted in FIG. 8, the skin panels 4 in the ball for a ball game of the second embodiment are sewn to the adjacent skin panels 4 with a thread 32. More specifically, each skin panel 4 is provided with the skin material 4c and the rear surface member 4d attached to the rear side of the skin material 4c. The rear surface member 4d is configured of a flexible stretchable material such as an EVA foamed material. Alternatively, the rear surface member 4d is configured by attaching one or a plurality of fabrics to a flexible stretchable material. Further, each skin panel 4 is in a state of being folded inward at portions that are sewn together with the thread 32. The skin material 4c and the rear surface member 4d of the skin panel 4 are both sewn by the thread 32 to the skin material 4c and the rear surface member 4d of the adjacent skin panel 4.

The rear surface of the skin panel 4 (is in intimate contact with) adheres on the outer surface of the fabric layer 3. This is due to (the pressure-sensitive adhesivity) sticky characteristic of latex used to (attach) laminate a plurality of fabric sheets when forming the fabric pieces 6. Since the skin panel 4 is bent inward at the outer circumferential portion, the fabric layer 3 is concaved inward in this portion. The skin layer 5 is attached in this state to the fabric layer 3.

A method for producing a ball for a ball game which is provided with the skin layer 5 having such skin panels 4 is explained hereinbelow. Two skin panels 4 in a state in which the rear surface member 4d in each skin panel is attached to the skin material 4c are overlapped such that the skin materials 4c are in contact with each other, and a side of the circumferential edge portions of the skin panels 4 are sewn together with the thread 32. Then, yet another skin panel 4 is likewise sewn to the skin panels 4, and by repeating this procedure, it is possible to form a spherical skin panel body with a part thereof being open and not sewn. In the spherical skin panel body, since the rear surface members 4d are positioned on the outside, and the skin panels 4 are positioned on the inside, the skin panel body is reversed using the opening. As a result, a skin panel body is obtained in which the circumferential edge portions of the skin panels 4 are bent inward. In such skin panel body, the rear surface members 4d are disposed on the inside of the skin material 4c exposed to the outside. A ball base body (obtained by forming the fabric layer 3 on the outside of the bladder 2) is inserted into the skin panel body by using the opening. The groove 8 in the fabric layer 3 is filled with the filler 10. In this ball base body, by contrast with the ball base body used in the aforementioned first embodiment, no adhesive is coated on the surface. Therefore, in the second embodiment, the coating step of coating the adhesive 14 is omitted.

The opening of the skin panel body is then closed, the skin panel body is set into a mold (not shown in the figure), pressurized, and heated. In this case, the fabric pieces 6 are bonded to the rear surface members 4d of the skin panels 4 by the latex of the fabric pieces 6. Therefore, at least portions of at least some of rear surface members 4d are bonded to the fabric layer 3 and the filler 10. The fabrication of the ball for a ball game is thus completed.

In the embodiment, an example is described in which the present invention is applied to a soccer ball, but such application is not limiting. For example, the present invention can be applied to balls for ball games that can be used in a variety of ball games, such as a volleyball ball, handball ball, basketball ball, rugby ball, American football ball, net-ball ball, futsal ball, beach soccer ball, Australian football ball, rugby league football, rugby union ball, and touch-ball ball.

In the embodiment, the fabric layer 3 is described which is formed by 12 fabric pieces 6 of a regular pentagonal shape, but such a configuration is not limiting. Essentially, any configuration may be used that has a fabric layer formed by sewing together a plurality of fabric pieces 6 of a polygonal shape.

In the balls for a ball game according to the first and second embodiments, the seam of adjacent fabric pieces 6 and the position where one and another skin panels 4 are adjacent to each other lie at different positions. In other words, the position where the side surfaces 4b of adjacent skin panels 4 are in contact with each other (position indicated by the solid line in FIG. 1) and the position where the circumferential edge portions 6a of adjacent fabric pieces 6 are in contact with each other (position indicated by the broken line in FIG. 1) do not correspond to each other. In contrast, in a ball for a ball game according to a third embodiment, the position where circumferential edge portions 6a of adjacent fabric pieces 6 are in contact with each other (seam of adjacent fabric pieces 6) corresponds to the position where side surfaces 4b of adjacent skin panels 4 are in contact with each other (the position where one and another skin panels 4 are adjacent to each other), as specifically described below.

As shown in FIGS. 9A and 9B, a hollow fabric body 35 used in the ball for a ball game according to the third embodiment includes four fabric pieces 6 each having oval shape. Adjacent fabric pieces 6 are sewn together. The fabric body 35 is formed for a rugby ball and therefore has an oval shape. The fabric body 35 constitutes a fabric layer 3 inside the ball for a ball game.

A tape material 20 is attached to each seam of the adjacent fabric pieces 6, and the fabric body 35 having a bladder 2 accommodated therein is set into an unillustrated mold to be heated and pressurized in the mold. Consequently, a filler 10 is formed on the seam of the adjacent fabric pieces 6. At this time, in the case where the molding face of the mold have no elongated grooves, the resultant fillers do not have a projecting rib, as shown in FIG. 9B. In other words, the outer surfaces of the fillers 10 substantially flush with the outer surfaces of the fabric pieces 6.

The skin panels 4 are disposed on the fabric layer 3 so as to correspond to the positions of the fabric pieces 6 and bonded to the fabric layer 3. In other words, each skin panel 4 is disposed on the fabric layer 3 so that the side surface 4b of the skin panel 4 lies on the filler 10. Further, a lower surface of a skin material 4c constituting the side surface 4b of each of the adjacent skin panels 4 is bonded to the filler 10 and the fabric piece 6. This allows the filler 10 to be located below the position where the side surfaces 4b of the adjacent skin panels 4 are in contact with each other. This makes it possible to prevent the side surfaces of the adjacent skin panels 4 from sinking into a groove 8 formed in the fabric layer 3.

In the case where elongated grooves are formed in the mold, a projecting rib 37 is integrally formed with each filler 10, as shown in FIG. 10. In other words, the filler 10 and the rib 37 are both made from the tape material 20 in the filling step. Therefore, an adhesive 14 is coated on the filler 10 and the rib 37 to bond the fabric layer 3 and a skin layer 5. As shown in FIG. 11, it is possible to dispose each skin panel 4 on the fabric body 35 so that the side surface 4b of the skin panel 4 lies along the rib 37.

Because the filler 10 is filled in the groove 8 defined between the adjacent fabric pieces 6, the filler 10 is located substantially inside of the curved surface defined by the outer surface of the fabric layer 3. On the other hand, the rib 37 projects outward from the outer surface of the filler 10. In other words, the rib 37 is located outside of the curved surface defined by the outer surface of the fabric layer 3.

As shown in FIG. 12, the rib 37 has a triangular cross-section tapering upward, and a height lower than (half or less of) the height (i.e. thickness) of the skin panel 4. The rib 37 extends along the outer surface of the filler 10 over the entirety of the filler 10. The rib 37 is disposed between the side surfaces 4b of the adjacent skin panels 4. The width of the rib 37 is narrower than the width of the filler 10, but the invention is not limited to this configuration.

Before disposing the skin panels 4 on the fabric pieces 6, an adhesive is coated on lower portions of the side surfaces 4b of each skin panel 4. Therefore, the lower portions of the side surfaces 4b of the adjacent skin panels 4 are bonded to opposite side surfaces 37a of the rib 37 by the adhesive coated on the lower portions of the side surfaces 4b of the skin panels 4 in cooperation with the adhesive 14 coated on the filler 10 and the rib 37. The side surface 4b of one of the adjacent skin panels 4 is bonded to one side surface 37a of the rib 37, whereas the side surface 4b of the other of the adjacent skin panels 4 is bonded to the other side surface 37a of the rib 37. On the other hand, the side surfaces 4b of the adjacent skin panels 4 are not bonded to each other. However, because the side surfaces 4b of the adjacent skin panels 4 are in contact with each other over the rib 37, the rib 37 cannot be seen from the outside. In other words, the side surfaces 4b of the adjacent skin panels 4 cover the rib 37.

The rib 37 may have a triangular cross-section tapering upward as shown in FIG. 12. Alternatively, the rib 37 may have an upper surface 37b to provide a square (for example, trapezoidal or rectangular) cross-section as shown in FIG. 13. Also in the case of the rib 37 shown in FIG. 13, the side surface 4b of one of the adjacent skin panels 4 is bonded to one side surface 37a of the rib 37, whereas the side surface 4b of the other of the adjacent skin panels 4 is bonded to the other side surface 37a of the rib 37. Also in this case, because the side surfaces 4b of the adjacent skin panels 4 are in contact with each other over the rib 37, the rib 37 is not exposed to the outside. The adhesive 14 is also coated on the upper surface 37b of the rib 37. The upper surface 37b may be bonded to the side surfaces 4b of the adjacent skin panels 4.

The rib 37 shown in FIG. 13 is wider than the width of the filler 10. However, the rib 37 may be narrower than the width of the filler 10. The filler 10 is integrally formed with, in addition to the rib 37, an extension portion 39 which extends laterally from the opposite side surfaces 37a of the rib 37. The extension portion 39 is made from the tape material 20 in the filling step in the same manner as the rib 37.

The extension portion 39 is in the form of a thin plate extending laterally from lower portions of the opposite side surfaces 37a of the rib 37. A lower surface of the extension portion 39 is fixedly attached to an upper surface of the fabric layer 3 (fabric pieces 6). An upper surface of the extension portion 39 is bonded to lower surfaces of the adjacent skin panels 4 by the adhesive 14. Thus, the skin layer 5 is bonded not directly to the filler 10 but to the members integrally formed with the filler 10. Even in the case of the rib 37 shown in FIG. 13, the extension portion 39 may be omitted and the lower surface of the skin material 4c constituting the side surface 4b of each of the adjacent skin panels 4 may be bonded directly to the fabric layer 3. On the other hand, in the case of having such a shape as shown in FIG. 12, a lower end of the rib 37 is narrower than the width of the filler 10. Therefore, the extension portion 39 is not formed. However, the extension portion 39 may be formed also in the case of the rib 37 having a triangular shape.

The balls for a ball game according to the third embodiment and the modifications thereof also prevent a stripe-like pattern from appearing on the outer surface of the skin panel 4.

The embodiment is summarized below.

The ball for a ball game includes: a bladder (2); a fabric layer (3) positioned on an outer side of the bladder (2), the fabric layer (3) having a plurality of fabric pieces (6) and a configuration in which circumferential edge portions (6a) of the fabric pieces (6) adjacent to one another are sewn together with a thread (12) and the circumferential edge portions (6a) are folded to the bladder (2) side; a filler (10) formed of a vulcanized rubber and loaded into a groove (8) formed on an outer side of a region where the circumferential edge portions (6a) of the fabric pieces (6) adjacent to one another are sewn together; and a skin layer (5) having a plurality of skin panels (4) and positioned on an outside of the fabric layer (3), the plurality of skin panels (4) being in close contact with (or tightly adhered on) the fabric layer (3).

In the present invention, since the groove (8) formed on a region where the circumferential edge portions (6a) of the mutually adjacent fabric pieces (6) are in contact with each other is filled with the filler (10), no gap is present between the skin layer (5) and the fabric layer (3) even in the location of the groove (8). Therefore, the region of the skin layer (5) that is positioned on the groove (8) does not sink into the groove (8). As a consequence, the formation of a stripe-like pattern on the outer surface of the skin layer (5) can be prevented. Furthermore since the filler (10) is formed of a vulcanized rubber, the filler (10) can be fixedly attached to the fabric layer (3) during the vulcanization into the filler (10). Further, since the fabric layer (3) is configured by sewing together a plurality of fabric pieces (6), a ball for a ball game which is soft to touch can be obtained.

The skin layer (5) may be in close contact with the fabric layer (3) and the filler (10).

Each skin panel (4) may include a skin material (4c) and a rear surface member (4d) attached to a rear side of the skin material (4c), a circumferential edge portion of the skin material (4c) being bent to follow the shape of the rear surface member. In this case, the rear surface member (4d) may be bonded to the fabric layer (3). In this case, since the skin layer (5) is bonded to the fabric layer (3), the skin layer (5) can be prevented from peeling.

At least one of the rear surface members (4d) may be bonded to the fabric layer (3) and the filler (10). In this case, since the skin layer (5) is bonded not only to the fabric layer (3) but also to the filler (10), the skin layer (5) can be prevented from peeling.

The skin panels (4) may be disposed adjacent to one another on the fabric layer (3) so that facing side surfaces (4b) of the adjacent skin panels (4) lie along the filler (10). This configuration makes it possible to prevent the side surfaces (4b) of the adjacent skin panels (4) from peeling off from the filler (10) and sinking into the groove (8).

A rib (37) may be formed on the filler (10), the rib extending along the filler (10). In this case, a lower portion of the side surface (4b) of each of the adjacent skin panels (4) may be bonded to the rib (37). This configuration allows the seam of the adjacent fabric pieces (6) to be reinforced by the rib (37). Furthermore, since the side surfaces (4b) of the adjacent skin panels (4) are bonded to the rib (37) by the adhesive, the adjacent skin panels (4) can be prevented from separating so that water is unlikely to enter into the gap between the adjacent skin panels (4).

Each skin panel (4) may have a skin material (4c) and a rear surface member (4d) attached to a rear side of the skin material (4c), and the skin panels (4) adjacent to one another may be sewn together with a thread (32). In this case at least portions of at least some of the rear surface members (4d) may be in close contact with the fabric layer (3) and the filler (10).

The method for manufacturing the ball for a ball game according to the embodiment includes: a step of sewing together circumferential edge portions (6a) of fabric pieces (6) with a thread (12) and forming a partially open hollow fabric body; a step of accommodating a bladder (2) inside the fabric body, and closing the opening of the fabric body to obtain a fabric layer (3); a filling step of heating the fabric layer (3) in which a tape material (20) formed of an unvulcanized rubber is disposed at a groove (8) formed on an outer side of a region where the circumferential edge portions (6a) of the fabric pieces (6) adjacent to one another in the fabric layer (3) are sewn together, the heating being performed in a pressurized state inside a mold, and obtaining a state in which the groove (8) is filled with a filler (10); and a step of forming a skin layer (5) on the fabric layer (3) and the filler (10).

With the manufacturing method, the groove (8) is filled with the filler (10) by heating the fabric layer (3) in which the tape material (20) formed of an unvulcanized rubber is disposed at the groove (8) formed on the outside of the region in which the circumferential edge portions (6a) of the mutually adjacent fabric pieces (6) are sewn together. In this case, the tape material (20) is vulcanized while changing the shape thereof so as to match the shape of the groove, and part of the rubber penetrates into the gaps between the fibers of the fabric pieces (6) and also into the gaps between the fibers and the sewing thread (12). As a result, the filler (10) is fixedly attached to the fabric pieces (6). During the vulcanization, the tape material (20) is pressed against the spherical inner cavity surface of the mold. Therefore, the tape material is deformed into a shape having the outer surface matching the outer surface of the substantially spherical fabric layer (3) during the vulcanization. As a consequence, the filler (10) can be formed without using a member that has been shaped in advance to match the shape of the groove (8).

In the method for manufacturing the ball for a ball game, a step of attaching the tape material (20) to the fabric layer (3) such as to cover the groove (8) of the fabric layer (3) may be included before the filling step. With the method, the operation of arranging the tape material (20) along the groove (8) can be facilitated.

Further, in the method for manufacturing the ball for a ball game, the circumferential edge portions (6a) of the adjacent fabric pieces (6) may be sewn together with the thread (12), with the tape material (20) being sandwiched therebetween in the step of forming the hollow fabric body. With the method, the step of attaching the tape material (20) can be omitted. Furthermore, the regions of the fabric pieces (6) that are sewn together with the thread (12) can be also effectively filled with the filler (10).

A coating step of coating an adhesive on the fabric layer (3) and the filler (10) obtained in the filling step may be further included. In this case, in the step of forming the skin layer (5), the skin layer (5) may be bonded onto the fabric layer (3) and the filler (10) coated with the adhesive.

In the step of forming the skin layer (5), a plurality of skin panels (4) adjacent to one another may be disposed so that facing side surfaces (4b) of the adjacent skin panels (4) lie along the filler (10).

In the filling step, a rib (37) may be integrally formed with the filler (10). In this case, in the step of forming the skin layer (5), a lower portion of the side surface (4b) of each of the adjacent skin panels (4) is brought to lie along and to be bonded to the rib (37).

In the step of forming the skin layer (5), the adjacent skin panels (4) may be sewn together with a thread (32).