US2693360A

US2693360A - Textile covered ball and method of making same

Info

Publication number: US2693360A
Application number: US256617A
Authority: US
Inventors: Goy Ronald Stansfield
Original assignee: Dunlop Tire and Rubber Corp
Current assignee: Sumitomo Rubber USA LLC
Priority date: 1951-11-15
Filing date: 1951-11-15
Publication date: 1954-11-02
Anticipated expiration: 1971-11-02

Description

Nov. 2, 1954 R. S. GOY TEXTILE COVERED BALL AND METHOD OF MAKING SAME Filed Nov. 15 1951 4 TTO/F/VE Y United States Patent TEXTILE COVERED BALL AND METHOD OF MAKING SAME Application November 15, 1951, Serial No. 256,617 12 Claims. (Cl. 273-61) This invention relates to tennis and like inflated balls and to methods of making such balls, and is an improvement in or modification of the invention described and claimed in co-pending patent application of Anderson et a1. Ser. No. 198,012, filed November 28, 1950, now Patent No. 2,652,094, September 15, .1953.

'In the abovementioned application'there is described and claimed a method of making textile covered balls having inflated cores which comprises covering an inflated core with a single thickness of composite yarn comprising a central thread Wrapped with a helix of yarn or roving of feltable material, effecting adhesion of the composite yarn to the core and raising and felting the covering in position on the core. Such a method applied'to the making of a tennis ball obviates the cutting out and fitting to a core of felt panels as in the case of a conventional ball and thus eliminates the wastage of felt left over after cutting. Furthermore the composite yarn is inexpensive as compared with the felted fabric used in the conventional ball and all waste wool can be re-carded and used again. The ball produced by the above method has the advantage that it does not suffer from an initial change in playing characteristics as does a conventional ball during shaking down of the felt panels on the core.

In my present invention I provide an improvement in the ball and in the method of making which embodies the said Patent No. 2,652,094. This improvement obviates the use of a composite yarn comprising a central thread wrapped with a helix of yarn or roving of feltable material which is an essential feature of that method and provides a more desirable, felted fibre finish.

According to my present invention a method of making a textile-covered ball having an inflated core comprises covering an inflated core with a single layer of a lowtwist yarn of feltable material wrapped in a spiral from one point in the surface of said ball to the diametrically opposite point as illustrated in said application Ser. No. 198,012. An adhesive is provided between the covering layer and the core which is then rendered effective. The covering layer is then raised and felted in position on the core.

Preferably the feltable yarn comprises a plurality of wool rovings twisted together or a number of singles of wool yarn twisted together. Preferably the degree of twist is between .75 and 3 T. P. 1. (turns per inch).

The ball of my invention and the method of making it are illustrated by way of example in the accompanying drawings, in which:

Fig. 1 is a perspective showing of the manner of winding a yarn onto a mandrel preparatory to winding the yarn onto an inflated core,

Fig. 2 is a similar view showing the manner of shaping and setting the yarn,

Fig. 3 is a section of turns of the yarn on the mandrel being coated with an adhesive,

Fig. 4 illustrates the manner of winding the yarn onto an inflated core,

Fig. 5 is a view of the ball after being wound with the shaped, adhesive coated yarn,

Fig. 6 is a section of a steam heated mold and yarn wound core being heated and shaped under pressure in said mold, and

Fig. 7 is a diagrammatic illustration of a conventional manner of loosening the fibres of the yarn on the ball to felt it to a smooth surface.

As illustrated in the accompanying drawings, a yarn 10 to be shaped and then wound onto an inflated core comprises eleven untwisted wool rovings 11 of .5 West of Englands count, twisted together with one T. P. I. The

yarn 10 is wound in a close helix 12 on a cylindrical mandrel 13 about 6" diameter and then steamed to set the yarn whilst at the same time compressing the coils axially of the mandrel as shown in Fig. 2 to form the yarn into rectangular, preferably substantially square, cross-section. The yarn is allowed to dry and an adhesive solutiomfor example, a 10% solution of balata in trichlorethylene, is sprayed as shown at 14, Fig. 3, onto the outside of the coils of the yarn to form a coating indicated at 15, Fig. 3. A rubber core 16 is also sprayed with adhesive solution and a single covering of the yarn 10 is then applied to the core 16, adhesive side of the yarn next to the core, in a spiral 17 starting at one point 18 on the core and finishing at the diametrically opposite point, the coils of the spiral being contiguous so that the yarn substantially covers the core.

The above method of winding the yarn in a helix on the mandrel is convenient for application of adhesive to the yarn and facilitates setting the yarn in substantially square crosssection so that when the yarn is spirally wound on the rubber core adjacent coils lie flush against each other and provide a more uniform covering for the core than composite yarn of more or less circular cross-section.

The twist in the yarn results in different rovings being coated with adhesive and contacting the core surface at different points along the yarn and thus assists in the effective adhesion of the yarn to the core.

The covered core is placed in a mold 19 which is then closed and heated at 110 C. for ten minutes, thus causing an increase in the pressure of gas Within the inflated core. The ball is thus molded under heat and pressure and the adhesive becomes plastic and penetrates into the coils of the yarn, thus ensuring satisfactory adhesion of the wool fibres to the core.

After molding, the Wool on the surface of the ball is raised by scratching with a wire brush 20, Fig. 7 or by placing the ball in a rotating drum lined with card clothing, or by any other suitable method such as raising with wires similar to those used in a conventional wool raising machine. The core covering is then felted by milling the ball in a 10% sodium oleate solution for about 40 minutes, the surface of the core being repeatedly distorted to cause migration and felting of the wool fibres to form a felted cover on the core.

The ball is well washed after felting and then given a final molding to impart a good finish to the appearance of the ball surface. If desired, the ball may be treated with an aqueous dispersion of polymethyl methacrylate before the final molding, in which case the polymethyl methacrylate softens during molding and helps to consolidate the felt by assisting adhesion between fibers in the covering.

In an alternative embodiment of the invention the yarn for the covering layer comprises twenty-five singles of wool yarn 6/s. West of Englands count, each with an initial twist of 3.5 2 T. P. I. which are twisted together with 1.5 S T. P. I. The yarn is applied to the rubber core as described in connection with the previous embodiment.

For sticking the yarn to the rubber core, instead of balata solution as described, adhesives such as rubber solution, rubber dough or a thermoplastic or thermosetting resin applied, for instance, as a solution in an organic solvent may be used.

Although the yarns described in the examples consist of Wool, a proportion of polyamide fibers, for example nylon, or polyester fibres, or other non-feltable thermoplastic synthetic fibers, e. g. cellulose acetate, may be introduced into the yarn. When the yarn comprises thermoplastic fibres which soften at the temperature of molding the ball, these help to consolidate the felt by assisting adhesion between fibres in the covering.

In general a satisfactory felted surface is not obtainable With a yarn which contains more than 50% by weight of non-feltable fibre and it is preferred to use not less than two parts by weight of wool fibre to one part by weight of non-feltable fibre.

In order to produce a ball which conforms to oflicial .3 7 requirements, the twist in the yarn is made such as to compact the yarn to obtain correct weight and size w 1th a single thickness covering on the core, allowance being made for unavoidable .losses of fibres during the raising and felting operations.

.In general the details for the production of a ball .disclosed in the principal patent are applicable .to the method according to the present invention, essential difference lying in the type of material used in the core covering layer, that is in the .present invention a composite yarn having acentral core thread is not used.

Having described my invention, what I claim is:

1. vA textile covered ball which comprises a hollow infiated .core of resilient material and a :spiral of fibrous material extending from .a point on the surface of :said core to the diametrically opposite point, .said spiral having contiguous turns of rectangularcross-section to cover completely said core and being cemented .to said core.

'2. 'The ball of claim 1 .in which said spiral is a roving of a twist of bet-ween 0.7.5 and 3 twists per inch.

3. The ball of claim 1 in which the exposed surface ofsaidspiralis felted to substantial uniformity.

4. A method of forming a textile covered ball which comprises shaping a .low twist yarn of fibrous material to a substantially rectangular cross-section, coatingoneface o'fsaid shaped yarn with an adhesive, winding said shaped yarn in a spiral from one point on an inflated .core to the opposite point in a continuous spiral of contiguous turns and with the coated face in contact with said core.

5. The method of claim 14in which the exposed surface of the spiral of contiguous turns is felted to a smooth continuous surface.

6. The method of claim 4 in which said spiral of fibrous material is molded on said core and said adhesive softened .to adhere to said core.

,7. The method of claim .6 in which .said spiral .covering is moistened with a solution of a plastic before molding.

8. A method of making a textile-covered ball according to claim 4 wherein the core wound with said shaped yarn is molded under heat and pressure and raising and felting the molded spiral of yarn'on said core.

9. .A method according to claim 4 in which the low twist yarn includes non-.felta'hle thermoplastic fibres which soften at the temperature of molding the ball.

10. .A method according to .claim 4 in which the low twist yarn comprises at least .two parts by weightof wool fibres to one part by weight .of non-.feltable fibres.

11. A method according to claim 4 wherein the yarn is composed of a plurality of wool rovings twisted .together.

12. A method according to claim 4 wherein the yarn is composed of a number of singles of wool yarn twisted together.

References Cited in .the'file 10f this patent UNITED :STATES PATENTS Number "Name Date 2,300,062 .Radford Oct. 27, 1942 FOREIGN PATENTS Number Country Date 230,554 Great Britain .Mar. 16, .1925 436,100 Great Britain -Oct. 4, 1.935 639,607 Great Britain July 5., 1950 23,399 Australia Feb. 3, 1936 of 19.35