JPH06178829A - Tennis ball free from adhesive agent in joint - Google Patents

Abstract

PURPOSE: To obtain a ball covered with stitchless fabric having a uniform surface without seams of adhesive agent nor any other rugged face. CONSTITUTION: This ball has a hollow spherical core made of elastic material and a plurality of felt panels 14 glued to the core using adhesive agent. As panels fixed to the core are covering almost all of the core, such almost continuously attached edges 18 of the panels 14 would form an almost continuous fabric covering not interrupted with seams of adhesive agent. The ball would improve the predictability as well as equality in aerodynamic and bound characteristics as it has an equal symmetry in radial direction. The fabric covering is desirably composed of a pair of felt fabric panels having a whole shape of dumbbell or dog bone. It is suitable to a tennis ball and related to the manufacturing process of the ball having above specifications and characteristics.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a fabric covered ball having a hollow spherical core made of an elastic material, and more particularly to a fabric panel forming the cover of the ball which is adhesive. It relates to a tennis ball which is intended to form a ball with uniform felt covering, which is not joined to each other along the edges, so that it is not interrupted by adhesive seams.

[0002]

BACKGROUND OF THE INVENTION Conventional tennis balls generally combine a pair of hemispherical shells made of an elastic material along their edges to form a hollow spherical core which is then Manufactured by covering with a pair of dog bone shaped felt panels. The hemispherical shell forming the core of the ball is formed by compression molding or injection molding. A hardened elastic adhesive, which is similar in composition to the material of the elastic core and is capable of bonding with the material, is applied to the edge of each hemispherical shell. The edges of each core are placed in contact, placed in a mold, and exposed to heat and generally pressure to cure, typically at about 5 to 1 normal atmospheric pressure.
It will form a single hollow spherical core containing gas at a pressure above 5 psi. The felt panel has a composition similar to that of the core material, and a hardened adhesive capable of bonding with the core material is applied to the back side or the opposite side of the felt pile of the felt panel so that the felt is shaped like a dog bone. It is formed by cutting so as to form. A curing adhesive similar to the core material and bondable to the core material is also applied to the edges of the felt panel. This is generally done by aligning the edges, stacking multiple felt panels, exposing the edges and mechanically compressing the felt panels,
This is done by repeatedly dipping in a bath containing the adhesive until a compatible reinforcement is achieved. felt·
Another method of applying adhesive to the edges of the panel involves gluing rope-like components during ball assembly. Both processes require complex automation or considerable effort and can be a significant part of the total manufacturing cost. The hollow spherical core is similar to the material of the core and is dipped in a hardened elastic adhesive capable of bonding with the material, or else a coating of the adhesive is applied. A felt cover is formed by laying or sticking a pair of dog bone-shaped felt panels, adhesively coated on the back and edges, onto the surface of the adhesively coated ball. The resulting assembly, consisting of a hollow spherical core and a pair of felt panels covering the entire outer surface of the core along the adhesive between the edges, was housed in a heated mold cavity, The cured adhesive applied to the outer surface of the core and the back and edges of the felt panel becomes an integral or additional part of the hollow spherical core.
A unitary structure will be formed. In general, the heat of the mold increases the air pressure inside the core, compressing the felt panel evenly between the core and the cavity wall of the mold,
A uniform bond between the felt panel and the core is promoted.
The adhesive applied to the edges of the felt panel forms an elastic seam that connects the felt panels together,
The seam forms a continuous, integral part of the spherical core.

Adhesive seams between felt panels of conventional tennis balls generally have a width of about 0.12.
It is 5 inches and forms a rib with a raised structure that causes the spherical hollow rubber core to be geometrically non-uniform. This non-uniform geometry results in non-uniform ball bending when impacted, resulting in unpredictable bouncing and flight trajectory during play. That is, the raised ribs associated with a typical tennis ball adhesive seam cause different orientations of the seam when the ball strikes the court surface or the racket gut, respectively. Furthermore, by bonding the edges of the panels together, the covering of relatively inelastic felt panels connected in series creates a girdle effect, stiffening the ball, reducing compliance and impact duration. Is shortened, the chance that the player spins the ball is reduced, and the time when the player can absorb the impact force is shortened. Shortening the impact time is known to cause obstacles such as tennis elbows. Also, when a player hits at or near the hardened glue seam of a conventional tennis ball, the player will experience a noticeably more severe feel than if he hits between the ball seams. .

Since the elastic seams of conventional tennis balls are formed of a material similar to, or at least chemically compatible with, the core, when cured, the seam adds to the core or is a continuous integral piece. Become part. Therefore, if the ball is hit directly at the seam and the ball is deformed, the core may deform in an arc around the seam, causing damage to the core material near the interior wall of the core just below the seam. This type of failure can occur abruptly after repeated direct hitting of the seam, resulting in a reduced useful life of the ball.

Adhesive seams have an aerodynamic effect on the ball and, as a result, generally make ball path prediction more difficult than for balls with a more uniform outer surface. It is considered to constitute a bumpy surface.

Generally, the seam of white adhesive is hard
A short play on the surface of the court will cause a dull gray color, making it difficult to see the ball. About 12.375 inches long and about 0.12 wide
For a 5 inch conventional tennis ball, the adhesive seam occupies about 8 percent of the total surface area. Thus, the reduced visibility of the seams significantly affects the overall visibility of conventional tennis balls. The present invention avoids the problem by abutting the edges of the panels and completely removing the adhesive seam.

Prior to the advent of the adhesive seam type described above around 1926, stitch seam tennis balls were commonly used. Tennis balls with stitched seams are sewn together tightly with small diameter threads, leaving a seam that is almost invisible, which is aerodynamic and structurally better than tennis balls with glued seams. The uniformity was much better. However, the process of producing a stitched seam tennis ball is extremely labor intensive and therefore expensive and cannot be easily automated. Because of this, adhesive seam tennis balls have the drawbacks associated with unpredictable bouncing and flying and tend to break or disappear, but they are much cheaper to produce and can be stitched. Hesitantly selected compared to the seam tennis ball by. Other disadvantages of stitched seams for tennis balls include the possibility of stitch failure and any seams not meeting the rules of the American Tennis Association, which stipulate that they must be "stitchless". .

Accordingly, adhesive seams have been regarded as an essential feature of stitchless tennis balls having a felt cover. Previously, it was believed that in order to secure the cooperating felt panels firmly to the core, the felt panels themselves had to be secured to each other along the edges by means of an adhesive seam secured to the core. Came.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stitchless tennis ball with a uniform felt cover that is not interrupted by adhesive seams.

[0010]

[Means for Solving the Problems] Seamless adhesive,
It has been found that it is possible to incorporate conventional adhesives and fabrication techniques into the process of manufacturing a tennis ball, in which case the felt panel is firmly secured to the core, but with its edges. Are not fixed to each other.

The process consists of forming a hollow spherical core made of an elastic material, applying adhesive to the core and the back of the felt, and cutting the felt into a dog's tooth shape. It The spherical core is preferably pressurized and, according to the invention, pressureless balls are also possible. Because it is cut into a dog bone shape, it is possible to wrap the felt panel around the core without overlapping edges. The conventional step of applying adhesive to the edges of the felt panel is completely eliminated according to the present invention. The assembled ball can then be cured in a heated mold cavity according to conventional practice.

The resulting ball consists of a hollow spherical core made of an elastic material with a tightly secured felt covering. In particular, the present invention provides an adhesive seamless tennis ball that overcomes substantially all of the drawbacks inherent in conventional tennis balls having an adhesive seam. Removal of all adhesive seams results in a tennis ball with a more uniform structure that provides more uniform flex and more uniform aerodynamic properties. In addition, the uniform flexing makes the tennis court or tennis racket bounce from the gut more predictable. The absence of adhesive seams also reduces the likelihood of core breakage due to uneven ball deformation around the seams when hitting the gut of a tennis racket. The uniform aerodynamic characteristics make the trajectory more predictable. Another advantage of the present invention is that there is no adhesive seam that tends to give a dull gray appearance, so when the play period is extended,
The improved visibility of the ball, and the seamless adhesive that tends to act as a reinforcing rib in conventional tennis balls, improves the feel when hitting the ball with a racket. Is included.

Another advantage of the tennis ball of the present invention is that the edges of the felt panels are not bonded together, which reduces the girdle effect. This results in a highly compliant tennis ball that tends to stay on the racket for a slightly longer period of time. As with baseballs, it is often falsely believed that only the seams produce the aerodynamic drag needed to bend a spinned tennis ball. Traditional tennis ball seams are different from smooth seamed baseball stitches with protruding stitches, and traditional tennis ball seams are hollow and aerodynamic to the fluffy surface of the felt panel. The drag is relatively small. As a result, the seamlessness of the adhesive has little effect on the aerodynamic drag of the tennis ball, and such effects that can be attributed to the seam are the effects that the player has on the ball according to the principles of the present invention. It is not important for extending the time you have to spin.

In addition to the above advantages associated with the use of the present invention, there are considerable advantages associated with the process of making balls in accordance with the present invention. Among other things, eliminating the conventional step of applying adhesive to the edges of felt panels reduces labor costs, lowers material costs, reduces volatile emissions and waste disposal, and is therefore environmentally friendly. Will result in more desirable use of adhesives and solvents, less floor space required for production, and improved quality control that can be attributed to the elimination of potential sources of error in the production process. .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings and more particularly to FIG. 2, there is shown a tennis ball with uniform felt covering, uninterrupted by adhesive seams or other surface irregularities.

As shown in FIG. 1, a tennis ball has four
Two components, that is, bonded by an adhesive,
A pair of hemispherical shells 12 and a pair of felt panels 14
Composed of. The hemispherical shell 12 is formed by subjecting a thermosetting elastic material to compression molding or injection molding. A curable elastic adhesive, which is bondable with the material and having a composition similar to that used to form the shell 12, is applied to at least one edge 16 of the shell 12. The edges 16 of the two shells 12, with at least one edge having an adhesive applied, are aligned in a butted manner within the cavity of the pressurizable mold and are cured at elevated temperatures, generally A hollow, spherical, monolithic core is formed, which desirably contains a gas at normal atmospheric pressure of about 5-15 psi. Another method for pressurizing a hollow core of a tennis ball, well known in the art and literature, is to enclose within the hollow core a liquid or solid material that upon heating produces a pressurized gas. Is. Pressurized balls are preferred, but it is also possible to make non-pressurized balls according to the principles of the present invention.

A pair of felt panels 14 cut into a dog bone or dumbbell shape are affixed or wrapped around a hollow spherical core with an adhesive. A dog bone or dumbbell shaped panel formed into a shape that conforms to the surface of the spherical core is shown in FIG. The felt panel 14 is tightly wrapped around the core so that the edge 18 of one panel is in continuous contact with the edge of the other panel so that there are no gaps, adhesive seams, or overlaps. It is sized and shaped so that it can form an almost continuous surface covering that is rare. Tightly wrapping around the core means laying or pasting the fabric on the surface of the core without bumps or wrinkles of the fabric. The nearly invisible seam 20 is formed by the butt edges of the panel 14. During assembly,
Although a small amount of adhesive can be inserted between the edges of the panel 14, the edge 18 of the panel is intentionally not applied with adhesive, so the edge 18 is barely adhesive. The assembled tennis ball is then placed in a mold cavity and heated to cure the adhesive, resulting in a uniform, continuous felt felt with few adhesive seams or other surface irregularities. It is desirable to form a tennis ball with a hollow, pressed spherical core of elastic material with a tightly secured covering.

If this tennis ball is different,
When cured, there are few adhesive seams that are part of the core, so the resulting tennis ball has a uniform spherical structure with no structural protrusions that cause uneven deformation when the ball is bent. There is. Also, the absence of adhesive seams or other surface irregularities imparts uniform aerodynamic properties to the tennis ball. The tennis ball of the present invention has a substantially uniform symmetry in the radial direction, that is, the plane passing through the center point of the tennis ball causes the tennis ball to have two protrusions or bumps. It is divided into almost the same one side.

The adhesive used in the assembly of the tennis ball is preferably thermosetting and is preferably composed of a material similar to and bondable to the core material. Becomes a continuous, integral part of the core.

Although the preferred embodiment consists of a pair of felt panels with a dog bone or dumbbell shape, more than two panels and panels of different shapes are possible, and the spirit of the invention Included within the range. Examples of other possible panel shapes include crescents similar to basketballs, pentagons and hexagons withdrawal as in the case of soccer balls. It is desirable that the panel be sized and shaped so that it completely covers the core and the panel edges are a snug but non-overlapping contact with each other.

Although an important aspect of the present invention is to provide a conventional adhesive seamless tennis ball, a tennis ball manufactured in accordance with the present invention incorporating various decorative seams. It is also possible to increase attractiveness and satisfaction. For example, tennis balls incorporate elastic bands that act as decorative seams so that they can be manufactured with a small gap of uniform width between the edges of the panel. Such elastic bands can be brightly colored to enhance visibility and appeal. To avoid some of the drawbacks associated with conventional adhesive seams, it is desirable that the decorative seam be bonded directly to the core and not to the edges of the felt panel. Alternatively, the outer surface may be provided with a decorative seam, for example by painting, printing, or hot stamping.

The description of the preferred embodiment has been provided in connection with its use as a tennis ball with felt covering. As used herein, felt means fluffy fabric cloth made from natural or synthetic fibers or a combination of natural and synthetic fibers. Other fabric coverings are possible and within the spirit and scope of the invention. Similarly, the preferred embodiment is a tennis ball, but other types of balls or different sized balls having the structures and features disclosed herein are possible and within the spirit and scope of the invention. Be done.

While the best mode and preferred embodiment has been set forth in accordance with patent law, the scope of the invention is not limited thereto, but by the scope of the appended claims.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a tennis ball according to the present invention showing the components prior to assembly.

FIG. 2 is the fully assembled tennis shown in FIG.
It is a perspective view of a ball.

FIG. 3 is a perspective view of a felt panel shaped to cooperate with a substantially identical panel to form a continuous spherical felt surface.

[Explanation of symbols]

 12 hemispherical shell 14 felt panel 16 edge 18 edge 20 seam

Claims (19)

[Claims] 1. A ball comprising a hollow spherical core having a plurality of fabric panels secured to it, with few adhesive seams such that the edges of the fabric panels join together. 2. The size and shape of the fabric panel is such that a slight gap of approximately uniform width is formed between the edges of the panel and the ball and further between the edges of the panel. Ball according to claim 1, characterized in that it is provided with a decorative seam fixed to the core along the gap. 3. The fabric panel of claim 1, wherein the size and shape of the fabric panel is such that it covers the entire core so that the edges of the panel are substantially continuous at the joints. ball. 4. The ball of claim 3, wherein the core comprises reinforcing ribs, protrusions, or other uniform structure with few bumps. 5. Ball according to claim 4, characterized in that the core is made of an elastic material. 6. The ball of claim 5, wherein the fabric covering is a felt fabric. 7. The ball according to claim 6, wherein the core contains a gas having a pressure higher than normal atmospheric pressure. 8. The pressure of the gas contained in the core is about 5
The ball of claim 7, wherein the ball is in the range of psi to about 15 psi. 9. Ball according to claim 8, characterized in that a decorative seam is provided on the outer surface of the ball. 10. A hollow spherical core made of an elastic material and a plurality of fabric panels secured to the core with an adhesive, the size and shape of the fabric panel covering the entire core. Since it has become
The edges of the panel are made of a nearly continuous fabric, where the joints are nearly continuous and not interrupted by adhesive seams.
A ball characterized by forming a covering. 11. The fabric covering edge is substantially free of adhesive at the edges thereof.
The ball described in 0. 12. The ball of claim 11, wherein the ball is substantially symmetrical in radial direction to provide uniform aerodynamic and bounce characteristics. 13. The fabric panel comprises felt.
Ball according to claim 12, characterized in that it is made of fabric. 14. The core has about 5 psi to about 15 ps
14. A ball according to claim 13, characterized in that it contains a gas at a pressure in the range of i. 15. The fabric covering comprises a pair of felt fabric panels having a generally dumbbell-like shape.
The ball described in 4. 16. A ball having a hollow spherical core made of an elastic material and a plurality of fabric panels secured to the core to form a substantially continuous fabric covering uninterrupted by adhesive seams. In the process for manufacturing, a) the step of forming a hollow spherical core from an elastic material, and b) the size and shape such that the core can be completely covered and the joints of the panel edges are almost continuous. The steps of obtaining a plurality of fabric panels, which are provided with: c) the fabric panels being glued to the core, the joints of the panel edges being almost continuous and interrupted by glue seams. A ball manufacturing process consisting of steps that result in the formation of a nearly continuous fabric covering. 17. At the edge of the fabric covering,
17. The ball manufacturing process according to claim 16, characterized in that it has been treated to ensure that it is almost free of adhesive. 18. The fabric panel is made of felt.
It is made of a fabric material, characterized in that
7. The ball manufacturing process according to 7. 19. The ball manufacturing process of claim 17, wherein the fabric panel comprises a pair of fabric panels having a dumbbell-like shape.