|Publication number||US3164952 A|
|Publication date||Jan 12, 1965|
|Filing date||Jun 17, 1963|
|Priority date||Jul 3, 1962|
|Publication number||US 3164952 A, US 3164952A, US-A-3164952, US3164952 A, US3164952A|
|Inventors||Neale Albert Edward Toney, Roberts Brian Charles|
|Original Assignee||Dunlop Rubber Co|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (4), Referenced by (3), Classifications (12)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Jan. 1965 A. E. 'r. NEALE ETAL 3,
METHOD OF MAKING TENNIS CORDS Filed June 17, 1963 In vemors Alberl: NQGJQ, grin C. Rober'zs B MZQMQMQ M I'M-i: orrreys United States Patent 3,164,952 METHOD OF MAKING TENNIS CORDS Albert Edward Toney Neale, Sutton Coldfield, and Brian Charles Roberts, Woodford Green, Essex, England, assiguors to Dunlo'p' Rubber Company Limited, London, England, a British company Filed June 17, 1963, Ser. No. 288,399 Claims priority, application Great Britain, July 3, 1962,
25,400/ 62 13 Claims. (Cl. 57-160) This invention relates to improvements in cords and especially to cords for the stringing of tennis, badminton and the like racquets.
The properties required in cords if they are to be satisfactory for stringing racquets are such that of the natural filamentary materials, only natural gut has found general acceptance. Gut is, however, very expensive and many attempts have therefore been made to produce cords from synthetic filamentary materials.
We have now found that a satisfactory cord can be made by a simplified process employing saturated steam at high temperature.
According to the invention a method of making cord for the stringing of tennis and the like racquets comprises applying to a monofilamentary textile core of a synthetic long-chain polymer at least one wrapping layer of a textile synthetic long-chain polymer material and passing the wrapped core through steam at a pressure of at least 50 pounds per square inch.
Usually the synthetic long-chain polymer is a fibreforming polymer having the formula RXR Y, where R and R are hydrocarbon radicals and X and Y are amide or ester radicals, such as nylon.
Generally the diameter of the monofilamentary core, which may be a single monofilament, is from 0.02 to 0.1 inch and each wrapping layer is made up by a length of monofilament of lesser diameter, usually from 0.002 to 0.01 inch.
The helix angle of the wrapping should be between 30 and 70 and preferably about 40 to 50 with respect to the transverse axis of the core and the wrapping may be applied as a ribbon of filaments in side by side relationship. In cases where more than one layer of wrapping is applied adjacent layers are wrapped in opposite directions, one clockwise and the other counterclockwise.
In order to bond the wrapping together and to the core so as to form a cohesive uniform cord both the steam pressure and the time during which the wrapped core is exposed to the steam must be accurately controlled. This is conveniently achieved in a continuous process in which the wrapped core is passed at a constant rate through a tube through which saturated steam is passed; the rate of travel and the steam pressure are adjusted so that the desired surface softening and bonding of the wrapping is obtained without detriment to the strength of the resultant cord. The bonding should be suflicient to allow sharp kinking and knotting of the cord without separation of the wrapping.
The invention will be further described in examples with reference to the accompanying drawings in which:
FIGURE 1 shows the steps in forming a cord and FIGURE 2 shows the construction of a cord formed by a monofilament core wrapped with two layers of monofilaments.
A monofilament core 1 of polycaprolactam having a diameter of 0.035 inch was drawn from a reel 2 by a driving pulley 3 and helically wrapped with two layers 4, 5 of monofilament caprolactam 0.005 inch in diameter. The first layer 4 was applied as a ribbon 6 of fifteen filaments 7 at an angle of 50 to the transverse axis of 3,164,952 Patented an. 12, 1965 the core in. a clockwise direction and the second layer 5 was applied as a ribbon 8 of twenty filaments 9 in a counter-clockwise direction at a similar angle. The wrapped core had a diameter of 0.06 inch.
The wrapped core was then passed at a rate of seven feet per minute through a tube 10 one foot long containing saturated steam at a pressure of 60 pounds per square inch under a tension of 3 pounds, and drawn over a free running pulley 11 onto a reel 12.
The wrappings of the resultant cord were sufficiently bonded to prevent separation when the cord was kinked sharply.
In a further example a multifilament core of seven 840 denier nylon yarns was braided with sixteen 210 denier nylon yarns one of which was coloured red and another black. The braided cord had a diameter of 0.073 inch.
The wrapped core was then passed at a rate of 7 feet per minute through the tube containing saturated steam at a pressure of 85 pounds per square inch under a tension of 3 pounds.
The braiding of the cord was fused together satisfactorily whilst retaining the pattern of the coloured yarns, the
' stiffness and coherence of the braiding being increased by the steam treatment.
The tube 10 employed in the above examples was fitted at each end with screw threaded brass plugs 13, 14 drilled with an 0.075 inch aperture to allow passage of the wrapped cord, which was threaded through the plug 13, passed through the tube 10 and threaded through the other plug 14 before screwing the plugs into the tube. The tube was also provided with a steam supply cock 15, a pressure gauge 16 and a steam exhaust cock 17. The tube 10 was mounted horizontally with the exhaust cock 17 at the lowermost portion; if it is desired to mount the tube vertically a steam trap should be provided at the lower end.
The process of the invention was simpler, more readily controlled and less expensive than a prior process involving the use of a phenol adhesive, the resultant cord was also more suitable. in colour than that produced by the prior process. Cords of highly translucent appearance can be produced by the process of the invention.
Having now described our invention, what we claim is:
l. A method of making cord for the stringing of tennis and the like racquets comprising applying directly to a monofilamentary textile core of a synthetic long-chain polymer at least one wrapping layer of a textile synthetic long-chain polymer material, and passing the wrapped core through steam at a pressure of at least 50 pounds per square inch for a period of time sufiicient to fuse the wrapping layer to the core.
2. A method as claimed in claim 1 wherein the core has a diameter of from 0.02 to 0.1 inch.
3. A method as claimed in claim 1 wherein the textile core is a single monofilament.
4. A method as claimed in claim 3 wherein the textile core is of a fiber-forming polymer having the formula RXR Y, where R and R are hydrocarbon radicals and X and Y are members of the class consisting of amide radicals and ester radicals.
5. A method as claimed in claim 4 wherein each wrapping layer is of a fibre-forming polymer having the formula RXR Y, where R and R are hydrocarbon radicals and X and Y are members selected from the class consisting of amide radicals and ester radicals.
6. A method as claimed in claim 2 wherein each wrapping layer is a length of single monofilament.
7. A method as claimed in claim 1 wherein the wrapping layer is applied at an angle of from 30 to 70 degrees ping layer is applied at an angle of from 40 to 50 degrees with respect to the transverse axis of the core.
9. A method as claimed in claim 7 wherein the wrapping is applied as a ribbon of filaments in side by side relationship.
10. A method as claimed in claim 1 wherein more than one wrapping layer is applied to the core, adjacent layers being wrapped in opposite directions, one clockwise and the other anti-clockwise.
11. A method as claimed in claim 1 wherein a wrapping layer of braid is applied to the core.
12. A method as claimed in claim 1 wherein tension is applied to the wrapped core whilst it is passed through the steam.
13. A method according to claim 6 wherein the single monofilament has a diameter of from 0.002 to 0.01 inch.
References Cited by the Examiner MERVIN STEIN, Primary Examiner.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2255890 *||Dec 22, 1938||Sep 16, 1941||Bigelow Sanford Carpet Co Inc||Floor covering manufacture|
|US2401291 *||Jun 11, 1943||May 28, 1946||Du Pont||Racket string|
|US2465996 *||Oct 4, 1946||Apr 5, 1949||Godfrey Bloch||Yarn and fabric|
|US3024589 *||Mar 6, 1956||Mar 13, 1962||Dunlop Rubber Co||Method of making racket cord|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US4568415 *||May 13, 1983||Feb 4, 1986||Isosport Verbundbauteile Gmbh||Method of producing strings for ball rackets, particularly for tennis rackets, and a string produced by this method|
|US5327714 *||Jul 30, 1992||Jul 12, 1994||Prince Manufacturing, Inc.||Synthetic string for sporting application|
|WO1983003998A1 *||May 13, 1983||Nov 24, 1983||Isosport Verbundbauteile Ges.M.B.H.||Method for manufacturing racket strings, particularly for tennis rackets, and strings manufactured by such method|
|U.S. Classification||57/6, 57/234, 57/15, 156/172, 273/DIG.600|
|International Classification||D04D1/00, A63B51/02|
|Cooperative Classification||Y10S273/06, A63B51/02, D04D1/00|
|European Classification||D04D1/00, A63B51/02|