GB2221624A

GB2221624A - Tennis ball and method of manufacturing the same

Info

Publication number: GB2221624A
Application number: GB8918207A
Authority: GB
Inventors: Jae Moon Song
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-08-10
Filing date: 1989-08-09
Publication date: 1990-02-14
Anticipated expiration: 2009-08-09
Also published as: JPH0513673B2; GB8918207D0; JPH0255071A; KR900002814A; GB2221624B; CA1322772C; IE64497B1; FR2635268A1; KR910007450B1; IE892559L; FR2635268B1

Abstract

A tennis ball comprises a hollow, spherical rubber ball (2) and a felt coating (4) attached thereto by an adhesive (3), the felt coating (4) being cut out from a felted fabric manufactured by knitting a circularly knitted high-pile fabric and laying in blended slivers of wool fibres and nylon fibres to produce a pile 5 needle-punching the circularly knitted fabric so that each pile fibre (5) is anchored at least at two parts thereof to the surface of the ground texture (6), and then forming a felted surface. <IMAGE>

Description

TENNIS BALL AND METHOD OF MANUFACTURING THE SAME The present invention relates to a tennis ball having relative durability, elasticity, flexibility and firmness, and a method of manufacturing such a tennis ball.

A tennis ball formed by coating a hollow, spherical rubber ball with raised felt is disclosed in Korean Patent Publication No. 550, pp. 75-78. Such a tennis ball coated with raised felt has the following drawbacks.

In manufacturing raised felt by subjecting felt to a raising process, excessive raising damages the felt, and hence the area of raising is limited, in general, to 50 to 60t of the surface of the felt. A tennis ball coated with such an insufficiently raised felt is unsatisfactory in elasticity and abrasion resistance. Furthermore, since the raised fibres are held simply at the opposite extremities by the ground texture, the raised fibres are liable to fall off the ground texture to deteriorate the durability of the ball.

The present invention provides a tennis ball comprising a hollow, spherical elastomeric ball, and a felt coating attached by an adhesive to the outer surface thereof, wherein the felt coating comprises a knitted highpile fabric containing pile fibres anchored at at least two parts to the fabric.

Preferably the pile fibres are slivers of wool, and nylon fibres. They may be anchored on the other surface of the fabric from the side on which they are laid.

The present invention also provides a preferable method of manufacturing a tennis ball comprising steps of: knitting a circularly knitted high-pile fabric with blended slivers of wool and nylon fibres laid in so as to be exposed on one surface of the fabric; brushing the surface of the circularly knitted high-pile fabric so that the pile fibres are inclined regularly in one direction at an angle to the surface of the circularly knitted high-pile fabric; needle-punching the brushed circularly knitted high-pile fabric so that each pile fibre is anchored on the back of the circularly knitted high-pile fabric at least at two parts thereof; milling the needle-punched circularly knitted high-pile fabric to obtain a felted coating fabric; and adhesively coating a hollow, spherical rubber ball with the felted coating fabric.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Fig. 1 is a partially cutaway front elevation of a tennis ball embodying the present invention; Fig. 2 is a diagrammatic illustration of a felted coating fabric, showing'the arrangement of a pile fabric; and Fig. 3 is an illustration of assistance in explaining the definition of a maximum inclination e of a pile fibre having a free end.

Referring to Fig. 1, a tennis ball embodying the present invention is formed by adhesively coating a hollow, spherical rubber ball 2 having a sealed space 1 with a felt coating 4. The felt coating 4 is attached to the outer surface of the rubber ball 2 by an adhesive film 3. In these features, this construction of the tennis ball is substantially the same as that of a conventional tennis ball.

The felt coating 4 of the embodiment is cut out from a felted fabric obtained by processing a circularly knitted high-pile fabric with blended slivers of wool and nylon fibres laid in so as to be exposed on one surface thereof as pile fibres. The surface of the circularly knitted high-pile fabric is brushed to arrange the pile fibres so as to be inclined regularly in one direction at an inclination to prepare the circularly knitted high-pile fabric to achieve the subsequent needle-punching process effectively.

The brushed circularly knitted high-pile fabric is needle-punched to push in the inclined pile fibres partially into the ground texture 6 of the circularly knitted high-pile fabric as shown in Fig. 2.

Referring to Fig. 2, each pile fibre 5 is secured only at the root 5x thereof to the ground texture 6 as indicated by an alternate long and short dash line before needle-punching. The pile fibre 5 is inserted in the ground texture 6 at least at two parts thereof by needle punching and is anchored to the ground texture 6 at parts 5b and 5d projecting from the back of the ground texture 6.

Thus, the pile fibre 5 extends in two low loop piles 5a and 5c, and a comparatively short pile 5e having a free end (hereinafter referred to as "free pile").

Subsequently, the needle-punched circularly knitted high-pile fabric is subjected to a known felting process for fulling to obtain a felted fabric for the felt coating 4.

The free piles 5e extend respectively at different maximum inclinations 0 in the range of O to 90" to cover the surface of the ground texture. The maximum inclination O is an angle XYZ, where the point X is the highest point on the short pile 5e, the point Y is the root of the short pile 5e, and the point Z is the point of intersection of the surface of the ground texture and a perpendicular to the surface of the ground texture, passing the point X.

The degree of needle-punching is dependent on the fibre length of the pile fibres. It is desirable to anchor a comparatively long pile fibre at least at three parts thereof. The duration of the milling process is regulated so that a finished felted fabric has desired firmness or flexibility.

Although the construction of the nap of the felted fabric has been described typically with reference to Fig. 2 showing only one of the pile fibres 5, actually, the nap consists of numerous pile fibres 5. A tennis ball coated with such a felt coating 4 having the low loop piles 5a and 5c, and the comparatively short free piles 5e mixed in a predetermined ratio is a novel tennis ball which has never been proposed previously.

The felt coating 4 thus obtained is attached by the adhesive layer 3 to the surface of the hollow, spherical rubber ball 2 to complete the tennis ball of the present invention.

The felt coating 4 cut out from the felted fabric obtained by processing the circularly knitted high-pile fabric has a surface entirely covered with a nap of overlapping pile fibres 5. The felt coating 4 is featured by the numerous free piles 5e and is conspicuously different from the conventional raised felt coating. The free piles 5e function just like springs to provide the tennis ball with a moderate elasticity. Furthermore, the extension of the free piles 5e at different inclinations 0 in the range of O to 90C further enhances the effect of the free piles 5e on the elasticity of the tennis ball.

The loop piles 5a and Sc overlapping each other in multiple layers cover the entire surface of the ground texture completely, whereas the pile fibres of the conventional felt coating cover the surface of the ground texture in a single layer at a surface covering ratio in the range of 50 to 60%. Hence the felt coating of the embodiment is superior to the conventional felt coating.

The springy function of the free piles 5e in combination with the satisfactory covering function of the overlapping loop piles 5a and Sc gives the tennis ball excellent flexibility and elasticity. Furthermore, since each pile fibre 5 is anchored at least at two parts 5b and 5d to the back of the ground texture and the adjacent loop piles overlap each other, the felt coating 4 has a sufficient durability. Moreover, the weight of the felt coating 4 can properly be determined by selectively deciding the type of fibres for forming the circularly knitted high-pile fabric.

Further explanation of the method will now be described.

Blended slivers of 5mm in diameter containing 65% by weight wool fibres and 35% by weight nylon fibres were produced by a known spinning process. Polyester spun yarns of Nc 30's were knitted on a high-pile knitting machine in a plain knitted fabric while the blended slivers were laid in the plain knitted fabric to obtain a tubular circularly knitted high-pile fabric having piles of 5cm in length.

The tubular circularly knitted high-pile fabric was slit and was subjected to a shearing process to make the pile fibres uniform in length. Then, the surface of the circularly knitted high-pile fabric was brushed to extend the pile fibres in the same direction respectively at inclinations in the order of 5". Then, the circularly knitted high-pile fabric was subjected to a needle pushing process, in which the circularly knitted high-pile fabric was needle-punched at a needle-punching density of 200 needles per square centimetre so that anchored parts of the pile fibres project from the back of the fabric by about 2mm. Subsequently, the needle-punched circularly knitted high-pile fabric was subjected to a milling process for fulling, and then the felted circularly knitted high-pile fabric was dried for finishing.

A felt coating was cut out from the felted circularly knitted high-pile fabric and attached adhesively to the surface of a hollow, spherical rubber ball to obtain the tennis ball.

The following process conditions for manufacturing such a felted fabric for the felt coating 4 was found to be desirable empirically.

Preferably, the blended sliver contains 60 to 80% by weight wool fibres and 20 to 40% by weight nylon fibres or, most desirably, 65% by weight wool fibres and 35% by weight nylon fibres.

A preferable length of the free portion of the pile fibres 5 before needle-punching is in the range of 2 to 6cm. When the free length is less than 2cm, it is difficult to anchor the pile fibre at two or more parts thereof, and hence the pile fibre 5 is liable to fall off the ground texture. Furthermore, reduction in the number of anchored parts, hence the number of the loop piles 5a and 5c, reduces the elasticity of the felt coating 4 adversely. On the other hand, pile fibres having a fibre length greater than 6cm increases the thickness and weight of the felt coating 4 excessively.

A preferable length of projection of the anchored parts from the back of the circularly knitted fabric is in the range of 1.5 to 2.5mm. When the length of projection is less than 1.5mm, the pile fibres are not anchored securely. When the length of projection exceeds 2.5mm, the thickness of the felt coating 4 increases excessively.

The blended sliver may be laid in the circularly knitted high-pile fabric by an amount sufficient to form a nap over the entire surface of the ground texture.

The circularly knitted fabric forming the ground texture may be formed of 100% polyester spun yarns, polyester-cotton blended spun yarns, polyester or nylon multifilament yarns, polyester or nylon texturized multifilament yarns, or polyester or nylon multifilament yarns and polyester and nylon texturized multi filament yarns.

A preferable weight ratio between the pile fibres and the ground texture, ie. the circularly knitted fabric, is 4 to 1.

The needle-punched circularly knitted high-pile fabric may be processed by the conventional milling process. Process conditions of the milling process are determined so that the felted fabric has a desired firmness and elasticity.

The tennis ball thus described has excellent elasticity and flexibility, and an extended life.

Claims

1. A tennis ball comprising a hollow, spherical elastomeric ball having a felt coating attached by an adhesive to the outer surface thereof, wherein the felt coating comprises a knitted high-pile fabric containing pile fibres anchored at at least two parts to the fabric.

2. A ball according to claim 1 wherein the pile fibres are blended slivers containing 60 to 80% by weight of wool fibres and 20 to 40% by weight of nylon fibres.

3. A ball according to claim 1 or claim 2 wherein the anchored parts of the pile fibres project from the back of the circularly knitted fabric by between 1.5 and 2.5mm.

4. A ball according to any one of claims 1 to 3 wherein the knitted fabric comprises substantially a) 100% polyester yarns, b) polyester-cotton blended spun yarns, c) polyester or nylon multifilament yarns or d) polyester or nylon texturized multifilament yarns or c) and d).

5. A ball according to any one of claims 1 to 4 wherein the weight ratio between the pile fibres and the knitted fabric is 4 to 1.

6. A method of manufacturing a coating to form the outer surface of a tennis ball including the steps of: knitting a high pile fabric; laying pile fibres on one surface of the fabric; aligning the pile fibres on the surface and anchoring at least two parts of the pile fibres to the fabric.

7. A method according to claim 6, wherein the fabric is circularly knitted.

8. A method according to claim 6 or claim 7 wherein the alignment of the pile fibres is achieved by brushing.

9. A method according to any one of claims 6 to 8 wherein the anchoring of the pile fibres is achieved by needle-punching.

10. A method according to claim 9 wherein the length of the free portion of pile fibres before needle-punching is in the range of 2 to 6cm.

11. A method according to any one of claims 6 to 10 wherein the pile fibres are laid in the knitted high pile fabric by an amount sufficient to form a nap over the entire surface of the ground texture.

12. A tennis ball comprising: a hollow, spherical rubber ball; and rubber ball by an adhesive; characterized in that the felt coating is cut out from a felted fabric manufactured through steps of knitting a circularly knitted high-pile fabric by laying blended slivers of wool fibres and nylon fibres in a circularly knitted fabric in knitting the latter on a circular knitting machine so that the component,fibres of the blended sliver extend as pile fibres on one surface of the ground texture of the circularly knitted high-pile fabric, needle-punching the circularly knitted high-pile fabric so that each pile fibre is anchored at least at two parts thereof to the other surface of the ground texture, and milling the needle-punched circularly knitted high-pile fabric.

13. A method of manufacturing a tennis ball, comprising steps of: producing a circularly knitted high-pile fabric by laying blended slivers of wool fibres and nylon fibres in a circularly knitted fabric in knitting the latter on a circular knitting machine so that the component fibres.of the blended slivers extend as pile fibres on one surface of the ground texture of the circularly knitted high-pile fabric; brushing the surface of the circularly knitted high-pile fabric to arrange the pile fibres so as to extend regularly in one direction at an inclination; needle-punching the circularly knitted high-pile fabric so that each pile fibre is anchored at least at two parts thereof to the other surface of the ground texture of the circularly knitted high-pile fabric; milling the needle-punched circularly knitted high-pile fabric to obtain a felted fabric; ; cutting out a felt coating from the felted fabric; and attaching the felt coating to a hollow, spherical rubber ball by an adhesive so that the hollow, spherical rubber ball is coated entirely with the felt coating.

14. A tennis ball substantially as herein described with reference to the accompanying drawings.

15. A method of manufacturing a tennis ball substantially as herein described with reference to the accompanying drawings.