GB1569530A

GB1569530A - Strings

Info

Publication number: GB1569530A
Application number: GB10150/78A
Authority: GB
Original assignee: Gosen Co Ltd
Current assignee: Gosen Co Ltd
Priority date: 1977-04-11
Filing date: 1978-03-14
Publication date: 1980-06-18
Also published as: IT7867806A0; FR2387058B1; JPS569496Y2; IT1156950B; FR2387058A1; BE865885A; JPS53140565U

Description

(54) IMPROVEMENTS IN AND RELATING TO STRINGS (71) We, GOSEN Co. LTD., a Japanese Company, of No. 4 Bungo-Machi, Higashi Ku, Osaka, Japan and JACOB van Rijswiz, a Dutch Subject of Mendelweg ib, Boskoop, Holland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to string made of synthetic resin monofilaments and especially to strings for use in stringing sports rackets, such as, for example, rackets for tennis, squash and badminton.

Strings for sports rackets have been proposed, which comprise a core of one or more synthetic resin monofilaments, which, if more than one may be aligned longitudinally or twisted or plaited together, and an outer helically wound wrapping of synthetic resin monofilaments, which may be the same as or different from the synthetic resin material of the core.

Such strings tend to have a more slippery surface than natural gut and thus there is a greater degree of relative movement between the strings at the crossing points in a string racket. The resultant wear causes string breakage.

The present invention provides a string for sports rackets which comprises a substantially circular cross-section core of one or more synthetic resin monofilaments and an outer helically wound wrapping of synthetic resin monofilaments, which may be the same as or different from the synthetic resin material of the core, the wrapping being formed from monofilaments of at least two different diameters arranged so that along the length of the string there are alternately portions of surface comprising smaller diameter monofilaments and raised portions of surface comprising at least one larger diameter monofilament.

Because of the formation of the wrapping on the core, when such a string is used to string a racket, two crossing strings can be arranged so that one is held between adjacent ridges formed by the larger mono filamentts) of the other thereby preventing relative movement between those strings.

Further, the surface of the string is so formed as to provide greater grip on a ball or the like struck by the racket thereby allowing greater control of the ball or the like especially in regard to the imparting of spin thereto.

In the string of the invention the diameter of the larger wrapping monofilament(s) is advantageously from 1.2 to 3.5 times, and preferably from 1.5 to 2.5 times, that of the diameter of the smaller wrapping monofilaments.

The diameter of the core is, with advantage, large compared to, and may be at least ten times greater than, the diameter of each wrapping monofilament.

Preferably the string is such that when viewed in cross-section, the portions of the surface with larger diameter monofilaments are spaced around the circumference of the string by from 1200 to 1800 of arc.

The monofilaments in the strings may be made from any suitable synthetic resin, for example, a polyester, such as polyethylene terephthalate, or preferably a nylon.

The string may, if desired, be an oil filled string such as that described and claimed in Patent Specification No. 1 228 171.

The invention will now be described in greater detail by way of example, with reference to the drawings in which: Fig. 1 is a perspective view of one form of string according to the invention; Fig. 2 is a cross section of the string shown in Fig. 1; and Fig. 3 is a cross section of a second form of string.

As shown in the drawing, the string com prises a core 1 made of a single monofilament of synthetic resin. Around the core 1 are helically wound a plurality of wrapping monofilaments 2, 3 also of synthetic resign.

These wrapping monofilaments comprise monofilaments 2 of small diameter and monofilaments 3 of diameter approximately twice that of the monofilaments 2. The monofilaments 3 are arranged in pairs and wound so that when the string is viewed in cross section as in Fig. 2, the cut ends of monofilaments 3 are diametrically op posed. In the space between the pair of monofilaments 3 are wound a plurality of monofilaments 2 defining a length of string surface 2a which is greater than the com bined diameters of the pair of monofila ments 3. For the string of Fig. 3 this length is comprised by sixteen monofilaments 2 and for that of Fig. 2 by twenty five mono filaments 2.

The different diameter monofilaments produce on the surface of the string raised areas 4 and depressed areas 5, which serve to reduce relative movement of two inter secting strings in a strung racket.

As shown in Fig. 3, the monofilaments 3 may be so arranged that in cross section of the string three pairs of monofilaments 3 spaced by 1200 around the core are seen, the pairs of monofilaments 3 being separated by a plurality of monofilaments 2. As is also shown in Fig. 3, the core may comprise a hollow monofilament the bore 6 6 of which may be filled with a lubricant as described in Patent Specification No.

1 228 171. Similarly, as shown in Fig. 3 some or all of the wrapping monofilaments may be hollow, as, for example, the mono filaments 3, the bores 7 of which may be filled with lubricant.

While the invention has been described with reference to a helically wound wrap ping wound directly on to the core it is possible and may for certain purposes be desirable to provide an intermediate helically wound wrapping, especially such a wrap ping wound in the opposite direction to the surface wrapping. Such an intermediate wrapping may be desirable depending, for example, on the strength or stiffness re quired in the string for a given purpose.

When the string of the invention is used for a racket, abrasion is reduced at the crossing point of a longitudinal string and a lateral string because the depressed area 5 formed by the surface synthetic resin mono filaments 2 of one string fits over the raised area 4 formed by the surface synthetic resin monofilaments 3 of the other string.

Moreover because there are raised and de pressed areas formed on the string surface by the surface monofilaments 2, 3, it is possible to prevent slip of a ball when it is hit, thereby improving contact of the ball on the racket and improving the variety of methods of striking the ball.

WHAT WE CLAIM IS: 1. A string for sports rackets which comprises a substantially circular cross-section core of one or more synthetic resin monofilaments and an outer helically wound wrapping of synthetic resin monofilaments, which may be the same as or different from the synthetic resin material of the core, the wrapping being formed from monofilaments of at least two different diameters arranged so that along the length of the string there are alternately portions of surface comprising smaller diameter monofilaments and raised portions of surface comprising at least one larger diameter monofilament.

2. A string as claimed in claim 1, wherein the diameter of the larger wrapping monofilament(s) is from 1.2 to 3.5 times that of the smaller wrapping monofilaments.

3. A string as claimed in claim 2, wherein the diameter of the larger wrapping monofilament(s) is from 1.5 to 2.5 times that of the smaller wrapping monofilaments.

4. A string as claimed in any one of claims 1 to 3, wherein the wrapping monofilaments are spaced so that, when the string is viewed in cross-section, the larger diameter monofilaments are spaced around the circumference of the string by from 1200 to 1800 of arc.

5. A string as claimed in any one of claims 1 to 4, wherein the synthetic resin is a nylon.

6. A string as claimed in any one of claims 1 to 5, wherein at least some of the monofilaments have axial bores which are filled with a lubricant.

7. A string as claimed in any one of claims 1 to 6, wherein the diameter of the core is large compared to the diameter of each wrapping monofilament.

8. A string as claimed in claim 7, wherein the diameter of the core is at least about ten times greater than the diameter of each wrapping monofilament.

9. A string as claimed in claim 1, substantially as described herein with reference to Fig. 1 or Fig. 2 or Fig. 3 of the drawings.

10. A sports racket whenever strung with a string as claimed in any one of claims 1 to 9.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. prises a core 1 made of a single monofilament of synthetic resin. Around the core 1 are helically wound a plurality of wrapping monofilaments 2, 3 also of synthetic resign. These wrapping monofilaments comprise monofilaments 2 of small diameter and monofilaments 3 of diameter approximately twice that of the monofilaments 2. The monofilaments 3 are arranged in pairs and wound so that when the string is viewed in cross section as in Fig. 2, the cut ends of monofilaments 3 are diametrically op posed. In the space between the pair of monofilaments 3 are wound a plurality of monofilaments 2 defining a length of string surface 2a which is greater than the com bined diameters of the pair of monofila ments 3. For the string of Fig. 3 this length is comprised by sixteen monofilaments 2 and for that of Fig. 2 by twenty five mono filaments 2. The different diameter monofilaments produce on the surface of the string raised areas 4 and depressed areas 5, which serve to reduce relative movement of two inter secting strings in a strung racket. As shown in Fig. 3, the monofilaments 3 may be so arranged that in cross section of the string three pairs of monofilaments 3 spaced by 1200 around the core are seen, the pairs of monofilaments 3 being separated by a plurality of monofilaments 2. As is also shown in Fig. 3, the core may comprise a hollow monofilament the bore 6 6 of which may be filled with a lubricant as described in Patent Specification No.