FR2705902A1 - Ribbed tennis string. - Google Patents

Abstract

String for tennis, comprising a central core (10), first outer filaments (12) rolled helically around this central core, having a diameter d, and second outer filaments (14) inserted between the first filaments, having a diameter D greater than d, the wound package (winding) as a whole being embedded in a coating resin, characterised in that there is an odd number, at least three, of second filaments, these three second filaments being arranged at the vertices of an isosceles triangle.

Description

i The subject of the present invention is a rope of

ribbed tennis.

  Tennis rackets include a sieve in which a string is stretched, which alone comes into contact with the ball. We know that ball striking techniques are varied. The players can thus give effect to the

  ball depending on how they hold the racket-

  te, that is to say according to the angle which the sieve makes with respect to the bale and according to the displacement of this sieve.

  Thus, we obtain effects of "lift" or "sli-

  ce ". For the" lift '", for example, the sieve is moved along a path that combines a curve that is substantially tangential to the ball with a

  translation from back to front.

  In order to give its full effect to the bale, it is necessary to avoid the sliding of this bale in relation to the stringing of the sieve during very short time.

  short where the ball is in contact with this sieve.

  Improvements have been developed and in particular

  ropes with ribs.

  The patent N FR-A-2 987 058 is thus known. It turns out that the existing ropes are not entirely satisfactory because it is necessary not only that there is a groove but also that this groove

  is positioned correctly in relation to the ball-

  the. For this purpose, the rib must be protruding by

  compared to the sieve and this to the right of each cross

two strings of this sieve.

  In the examples of the prior art, the position-

  ment of the rib is random so that the effects obtained are not as well rendered in practice. It is therefore imperative that the rib is positioned before striking and that it

  be kept in this position during typing.

  To this end, the tennis string according to the invention, of the type comprising a central core, first outer filaments wound helically around this central core, with a diameter d and second outer filaments interposed between the first filaments, with a diameter D greater than d,

  the whole winding being embedded in a re-

  sine of coating, is characterized in that the number of second filaments is odd and at least equal to three so that they are positioned at the vertices

of an isosceles triangle.

  According to a preferred embodiment of the in-

  vention, this tennis string includes five strings

  elements of diameter D, arranged regularly on the periphery, the diameters D, d being such that there is a straight line tangent to the two filaments of

  diameter D, this straight line forming a support base.

  According to a particular embodiment of the invention

  tion, the five filaments are made of a material

  abrasion resistant, particularly

graphite.

  Thus, according to a specific embodiment of the invention, the cord comprises a core with a diameter of 0.80 mm, the first and second filaments having respective diameters of 0.18 and 0.30 mm, the resin

  coating leading to an outside diameter

  first filament round 1.30 mm and outside at

second filament of 1.50 mm.

  The present invention is described below with regard to

  of the single figure which represents a perspective view

  pective of a portion of tennis string according to

  the invention which comprises a central core 10, made

  sée in a synthetic material which is obtained by wire drawing, while at the periphery of this central core 10 the first filaments 12 of a diameter d are wound helically as well as second filaments 14 interposed between the first

filaments 12.

  In the embodiment presented, the cord comprises eight first filaments 12 of diameter d,

  distributed in pairs with interposition of five se-

  conds filaments 14 of diameter D greater than the diameter

be from the first filaments.

  This is clearly visible on the cut at the end of the rope. All of the diameters are studied so that three of the second filaments out of the five constitute a triangle T shown in phantom in the figure, this triangle T being isosceles, with a second filament 16 at its apex and two second filaments 18 at the

two ends of its base.

  As shown in the figure, between the two second filaments 18, constituting the base

  of the triangle T, are interspersed two first fila-

  ments 12 and the diameters of the filaments are such that this pair of first filaments and the two filaments 18 constituting the ends of the base of the triangle T are tangent to the same straight line D.

  A coating resin 20 ensures the blocking of the diff-

  ferent filaments and the connection with the central core 10. It creates a constant thickness over the

  periphery of the rope and does not change the position-

filaments.

  In the embodiment shown, it can be seen that whatever the rotation of the rope, it will always be in a stable position by pressing on

  the rope with which it is crossed.

  Now the stable position leads to an orientation

  such that a large diameter filament is im-

  from the opposite side and therefore protrudes at the

crossing right.

  We note that this rope allows sliding base against base, which allows repositioning

  ropes between them, especially at the crossroads

  thanks to the elasticity of these ropes and

their prior tension.

  Such a positioning leads to a very high stress on the protruding filament and so as to increase the longevity of the rope according to

  the invention, it makes sense to make the fila-

  large diameter parts made of a material resistant to

abrasion, especially in graphite.

  In order to fix orders of magnitude, the rope which

  just described comprises a core 10 of a diameter

  be 0.80 mm, the first and second filaments have effective diameters of 0.18 mm and 0.30 mm so as to lead to outside diameters after resin coating of 1.30 mm in line with small diameter filaments and 1.50 mm in line with the filaments

large diameter.

Claims (5)

  1. Tennis string comprising a central core   trale (10), first outer filaments (12) wound helically around this central core, with a diameter d, and second filaments   (14) interposed between the first wires   ments, with a diameter D greater than d, the entire winding being embedded in a coating resin characterized in that the number of second filaments is odd, at least equal to three, these three second filaments being arranged at the vertices of an isosceles triangle. 2. Tennis string according to claim 1, characterized in that it comprises at least five   second filaments of diameter D, distributed annular-   lie regularly at the periphery of the central core, the diameters D and d being such that it   exists a line tangent to the two second fila-   successive elements so as to form a basis support.   3. Tennis string according to claim 2, characterized in that the five second filaments   are made of an abrasion resistant material.   4. Tennis string according to claim 3, characterized in that the material used is graphite. 5. Tennis string according to any one   of the preceding claims, characterized in   that the core (10) has a diameter of 0.80 mm, the pre-   first (12) and second (14) filaments have diameters   very respective 0.18 and 0.30 mm, the resin coating leading to an outside diameter to the right of the first filaments of 1.30 mm and to the right of the second filament of 1.50 mm.