WO2000024473A2

WO2000024473A2 - Improved stringing of sports rackets and relative method

Info

Publication number: WO2000024473A2
Application number: PCT/EP1999/008147
Authority: WO
Inventors: Francesco Nicola Ilario Cima
Original assignee: Cima Alethes
Priority date: 1998-10-22
Filing date: 1999-10-21
Publication date: 2000-05-04
Also published as: ITBG980031U1; AU6342999A; WO2000024473A3; IT244828Y1

Abstract

An improved stringing for sports rackets (10) ranging from those used in tennis, squash, badminton, racketball and other sports or similar games, including a frame (11), produced to support a crisscross of strings (17) with a basically equilateral triangle weave (13), in which the strings (17) are tightened in three directions and intersect with each other.

Description

"Improved stringing of sports rackets and relative method".

The present invention refers to an improved stringing for sports rackets ranging from those used in tennis, squash, badminton, racketball and other sports or similar games, and to the relative method.

At present, in tennis, squash, badminton and in all those sports which involve repeatedly hitting a ball, shuttlecock or any other object, so that the

^• opponent cannot successfully return it, normally rackets are used of dimensions and forms which specifically vary according to the particular type of sport but which, anyhow, are made of wood, plastic, aluminium or other compound materials of quality and/or strengthened with glass or carbon fibres, graphite or titanium.

The strings used are normally made of synthetic fibre and are tightened to the racket frame or a support coupled to the frame, so that their positioning follows two right-angled directions

■ with each other. In particular, stringings are carried out with strings arranged in two crosswise directions, with respect to the racket's median axis, or positioned according to the horizontal and vertical directions with respect to the plane passing through the racket frame; the latter stringing method is the only one in current use. However, traditional rackets, because of the fact that their relative stringings are mainly bidirectional, present serious drawbacks particularly because, each time the ball is struck, the strings tend to move from their seatings and thus no longer retain their original order. As a result, the strings easily tend to wear out and break and, in addition, do not allow optimum ball control during play, as well as with poor load distribution from impact with the ball. Therefore, the aim of the present invention is to eliminate the technical drawbacks encountered by producing an improved stringing method of sports rackets that allows excellent control and efficacy when hitting balls, shuttlecocks or other objects to serve or return in games or sports such as tennis, badminton, squash and racketball.

Another aim of the invention is to produce sports racket stringing that allows improved characteristics concerning power, speed, precision and ball control application, with respect to the known types of stringing methods. Another aim of the present invention is to point out a stringing method relative to the above improved racket.

An additional aim of the invention is to point out a sports racket with a stringing, according to the present invention, that conforms to the provisions of the international sporting rules, which results in reduced string wear with respect to sports rackets currently in use. A further aim of the present invention is to produce a sports racket stringing of substantially reasonable cost by virtue of the gained advantages. These and other aims, according to the present invention, are reached by carrying out the improved stringing of sports rackets, according to claim 1, and indicating a relative stringing method, according to claim 12.

Of advantage the present invention has, as its subject, a new type of racket stringing process used in tennis, squash, badminton, racketball and other games and sports suitable for hitting balls or other objects to serve or return, that allows the achievement of better game characteristics and improved hitting efficiency, together with reduced wear over time, due to less stress, as for the face or surface of the strung frame, where impact loads are more uniformly distributed with respect to traditionally strung frames.

Additional characteristics and advantages of the improved stringing of sports rackets, according to the invention, will be made clearer by the following illustrative and unrestricted description which refers to the enclosed outline designs, in which: - figure 1 is a first front view of a first embodiment form of a sports racket with improved stringing, according to the invention;

- figure 2 is an enlarged view of a detail of the sports racket's stringing as in figure 1, according to the present invention;

- figure 3 is a first front view of a second embodiment of a sports racket with improved stringing, according to the invention;

- figure 4 is an enlarged view of a detail of the racket's stringing as in figure 3, according to the present invention;

- figure 5 is a second front view of the sports racket as in figure 1;

- figure 6 is a second front view of the sports racket as in figure 3; figure 7 is a front view of a sports racket with a traditional type stringing. It should be noted henceforth that, although the detailed description of the examples contained in the present invention refers to a improved stringing for tennis rackets, the general considerations on the type of stringing adopted on such racket may be equally applied, to sports rackets in general, such as squash, badminton, racketball rackets and those used in other sports or games in which it is necessary to use a racket or other item of equipment, requiring stringing, suitable for serving and returning a ball, or any other object, to the opponent. With reference to the figures quoted, 10 generically refers to a sports racket, in particular a tennis racket, including a base 14, a handle 15 and a frame 16.

The strings 17, usually of synthetic type, of the racket 10, intersecting, form a crisscross or stringing, supported by a usually elliptically

^■ shaped frame 11 of the racket 10.

The stringing process of the racket 10, according to the present invention, is carried out so that the strings 17 go in three different directions and that, intersecting, they form a basically equilateral triangular shaped weave, denoted by 13 in the diagrams, all vertex angles being +50/+70 sexagesimal degrees and, especially, +60 sexagesimal degrees. The strings 17 are divided into three groups, of which each group presents strings 17 basically parallel to each other and variously positioned with respect to the X and Y axes, as shown in figures 1 and 3. It should be noted that one single, two or three different strings with suitable fixing and ramification methods may be used for the three string groups 17.

In particular, in a first preferred embodiment, and unrestricted, of the present invention, shown as an example in figures 1 and 2, the basically parallel strings 17A, are arranged so as to form angles of

+20/+40 sexagesimal degrees, and preferably +30 sexagesimal degrees, starting from a reference origin, 0, on the X axis and following the direction of arrow A, intersecting the imaginary axis X, that represents the frame's (11) axis of symmetry, in this case elliptically shaped, and being perpendicular to the Y axis. On the other hand, the same embodiment has a basically parallel series of strings 17B, arranged to form angles between -20/-40 sexagesimal degrees and preferably -30 sexagesimal degrees (i.e.: angles within +140/+160 degrees and preferably equal to +150 degrees) , beginning from the origin 0 of the X axis and always following the direction of the arrow A, intersecting the imaginary axis X and to form angles between +110/ +130 sexagesimal degrees and preferably equal to +120 sexagesimal degrees with the strings 17A.

Finally, the strings denoted by 17C in figures 1 and 2 are basically parallel to each other and essentially arranged parallel with respect to the focal axis Y, i.e. in a vertical direction with respect to the plane that passes through the frame 11 of the racket 10, as the Y axis may further constitute a symmetry axis of the racket 10. In this embodiment of the present invention, the vertical strings 17C may be joined, one on top of the other, inside each single hole, notch or other fixing method, generically denoted by 12 in the diagrams.

Therefore, it is envisaged that the above mentioned strings 17C alternately intersect sidelong with strings 17A, 17B; in actual fact, where one of the two vertical strings 17C passes above strings 17A, 17B, sidelong to it, the other vertical string 17C passes below it and so on.

As for the stringing method, according to the invention, first the cross strings 17A and 17B are strung (in the desired order) , so that each string 17 of group 17A is placed in contact with each string of group 17B and, at the contact points, pass alternately, from one part and from the other with respect to said string.

As a result, the vertical strings 17C are strung, so that they intersect the cross strings 17A, 17B precisely corresponding to the vertices VI relating to the angles that are formed, by effect of the aforesaid cross strings 17A, 17B and they alternately cross them, from one part and from the other of the frame 11, as better illustrated in figure 2. In any case, the stringing which refers to the X and Y axes may be turned through an angle of 360 sexagesimal degrees on the plane of the frame 11 or other support.

The strings 17A, 17B, 17C are fixed inside notches, holes or generic fixing sites 12, appropriately shaped and corresponding to the direction of the stringing' s positioning.

The fixing implements are located at different points along the frame 11 and are each perpendicularly arranged to the frame's (11) tangent in the point, utilising a passing hole of string 17 inside the frame 11 of the racket 10 or inside an anchorage support of rigid or semi-rigid material, that is fixed to the frame 11 with strings, threads, rings, screws, rivets or elastic bands.

The strings are preferably fixed in correspondence to set areas of the frame 11.

In particular, the strings 17A, 17B, 17C are fixed inside the hole or notch 12 of the frame 11 or any support, in correspondence to areas of the frame 11 diametrically opposite, with respect to a hypothetical centre C of the same frame 11. For simplification purposes of the design, such areas, denoted respectively by R, S and T in figure 1, have been brought out of the racket 10 and correspond, in practice, to the sides Rl, SI, Tl of

• the hypothetical hexagon that may circumscribe the frame's (11) outline, in this case elliptic, and is represented for convenience and as an example in figure 5. The illustrative embodiment of the present invention, shown as an unrestricted example in figures 3 and 4, presents a series of strings 17D, all basically parallel to each other and arranged to form angles of +50/+70 sexagesimal degrees, preferably +60 sexagesimal degrees, beginning from the origin 0 of the X axis and always following in the direction of the arrow A, intersecting the imaginary axis X that may make up the axis of symmetry of the hypothetical elliptic frame 11 and being perpendicular to the focal axis Y. On the other hand, the same embodiment has a series of strings 17E, all basically parallel to each other and arranged to form angles of -50/-70 sexagesimal degrees and preferably - 60 (i.e.: +110/ +130 degrees and preferably +120 degrees) sexagesimal degrees, beginning from the origin 0 of the X axis and always following in the direction of arrow A, intersecting the imaginary axis X and arranged to form angles of +50/ +70 sexagesimal degrees and equal to +60 sexagesimal degrees with strings 17D. Finally, the strings denoted by 17F in the figures 3 and 4 are basically parallel to each other and arranged basically parallel with respect to the imaginary axis X, i.e. in a horizontal direction with respect to the plane that passes through the frame 11 of the racket 10. Also in this embodiment, firstly the cross strings 17D and 17E are strung, in the desired order and in the way already described previously and, in succession, the horizontal strings 17F.

The latter intersect the cross strings 17D, 17E precisely in correspondence to the vertices VI relating to the angles formed by effect of the aforesaid cross strings 17D, 17E and cross them, alternately, from one part and from the other of the frame 11, as better shown in figure 4. Also in this case, the strings 17D, 17E, 17F are fixed inside notches, holes or general fixing implements 12 of a frame 11 or an identical support, appropriately arranged, in a such way to give a shape corresponding to the directions of the stringing' s positioning. The strings are preferably fixed in correspondence to the set areas of the frame 11, diametrically opposite with respect to the hypothetical centre C of the same frame 11; such areas are denoted, respectively, by U, V and Z in figure 3, to assist the reader' s individuation and they virtually correspond to the sides U2, V2, Z2 of the hexagon circumscribing the frame's 11 elliptic outline and better shown in figure 6.

In both embodiments of the present invention is formed, as a whole, a stringing with a weave whose gaps are ideally shaped, each being basically equilateral triangular shaped, denoted by 13 in the figures and in which the strings 17 form the sides of the aforesaid triangles 13.

This arrangement of the strings 17, specifically conforms to the provisions of national and international sporting rules, not allowing the same to move from their seatings, since each time that the ball or object is hit, to serve or return it during play, the strings, if slightly moved, naturally and automatically return back to their original seatings, due to the special configuration of the frame's 11 stringing.

The fact that the strings 17 generally stay in position during play, with respect to traditional type stringings, means reduced wear.

Besides, the directivity, power and the effects of strokes that may be achieved with traditional types of stringing were examined. Afterwards studies, extensive tests and experiments were carried out, in order to be able to optimise such parameters, increasing the self-point or sweet spot, i.e. the stringing area available to strike the ball without unwanted effects, and guaranteeing better load distribution upon impact with the ball, compared to traditional stringings, so as to be able to apply better spin to the same ball. In particular, figures 5 and 6 represent an ideal "self-point", comprising the SP area situated inside the ES sides of a hexagon inscribed inside the frame 11.

However, experimental results have shown that the true "self-point" is made up of the SP1 area made inside an ellipsoid, denoted by L, that is basically concentric to the frame's (11) elliptic outline.

Figures 5, 6 and comparison with figure 7, that represents the ideal "self-point" SPT area attainable with a sports racket 100, having a traditional 121 stringing and supported by a frame 160 of known type, immediately reveal the fact that the "self-point" is more than doubled and that, in addition, the amount of string used in the racket 10, subject of the present invention, is more or less identical to that used in the known type rackets. Having tested the stringing according to the present invention, it was virtually ascertained that it and, also to a lesser degree generally all the stringing types with strings tightened in more than two directions, unlike stringings found on traditional rackets, offer the following advantages:

- better load distribution upon ball impact on the stringing;

- a more than doubling in size of the "self-point" i.e. the area where ball hitting is optimised, compared to known type rackets;

- better ball control, with respect to traditional rackets, due to the stringing' s basically equilateral triangle weave; - the amount of string used is basically equal to that used for traditional rackets and, hence, is of similar weight.

Finally, utilisation of the stringing according to the present invention also means the way of hitting the ball changes slightly that, in this specific case, will spin better in flight and that, in any event, will not experience strange, random or unwanted effects. It is clear from the description provided that the characteristics of the improved sports racket stringing, subject of the present invention, offer clear advantages.

Finally, it is evident that several other variations could be made to the racket, subject of the present invention, without straying from the principles of originality inherent in the inventive idea, as is also clear in the invention's practical implementation, the materials, forms and dimensions of the details shown could be otherwise, according to requirements, and which could be replaced by other technically equivalent materials.

Claims

CLAIMS 1. An improved stringing of sports rackets (10), particularly for tennis, squash, badminton, racketball and other sports or games, comprising a crisscross of strings (17) tightened and either fixed to a frame (11) or other support part, so as to be able to serve and/or return balls or other similar objects, characterised in that it includes at least one string (17; 17A, 17B, 17C; 17D, 17E, 17F) , positioned according to at least three different directions lying on a plane which passes through a surface determined by said frame (11) .

2. A stringing as in claim 1, characterised in that said strings (17; 17A, 17B, 17C; 17D, 17E, 17F) , that are positioned according to at least one of said three directions, determine, in turn, directions that are basically parallel to each other.

3. A stringing as in claim 1, characterised by the fact of being made up of at least one group (17A,

17B, 17C; 17D, 17E, 17F) of strings (17) and being formed by a weave that includes a number of (13) basically equilateral triangles.

4. A stringing as in claim 3, characterised in that said triangles (13) cover almost entirely said surface determined by the frame (11) .

5. A stringing as in claim 3, characterised in that said strings (17) form sides of said triangles (13) and they intersect forming equal angles with each other of between +50/ +70 sexagesimal degrees and, especially, equal to 60 sexagesimal degrees.

6. A stringing as in claim 1, characterised in that an initial group of strings (17) is made up of first strings (17A) , all basically parallel to each other and inclined at an angle of +110/+130 sexagesimal degrees and, especially, equal to +120 sexagesimal degrees, with respect to the second strings (17B), these also being basically parallel to each other and belonging to a second group of strings (17), a third group of third strings (17C) basically arranged parallel to each other and according to a direction basically parallel to a longitudinal axis (Y) of hypothetical symmetry of said racket (10), so as to intersect said first (17A) and second strings (17B) at all their intersection points (VI) .

7. A stringing as in claim 1, characterised in that a first group of strings (17) is made up of first strings (17D) , all basically parallel with each other and inclined at an angle of +50/ +70 sexagesimal degrees and, especially, equal to +60 sexagesimal degrees, with respect to second strings

(17E), these also basically parallel with each other and belonging to a second group of strings (17), a third group of third strings (17F) being arranged basically parallel with each other and according to a direction (X) perpendicular to a longitudinal axis (Y) of hypothetical symmetry of said racket (10) , so as to intersect said first (17D) and second strings (17E) at all their intersection points (VI) .

8. A stringing as in claim 1, characterised in that each group (17A, 17B, 17C; 17D, 17E, 17F) of strings (17) covers a set area, in such a way that said strings (17) are fixed to parts (12) arranged in at least two points (R, S, T, U, V, Z) of said frame (11) .

9. A stringing as in claim 1, characterised in that said frame (11) shows a series of fixing means (12) of said strings (17), which conform to said directions of positioning.

10. A stringing as in claim 9, characterised in that said fixing means (12) of the strings (17) are arranged perpendicularly to a tangent at said surface determined by said frame (11) at a point through which said string (17) to be fixed passes.

11. A stringing as in claims 6 or 7, characterised in that said first (17A, 17D) and second strings (17B, 17E) intersect with each other passing, alternately, above and under one another, i.e. from one part and from the other with respect to said surface determined by said frame (11), said third strings (17C, 17F) intersecting said first ones (17A, 17D) and second strings (17B, 17E) , alternately, above and under each other, i.e. from one part and from the other of said surface determined by said frame (11) .

12. A stringing method of sports rackets (10), characterised in that it includes the following stages, in the order:

- the stringing of two series of cross strings (17A, 17B; 17D, 17E) , with respect to an axis of symmetry (Y) of said racket (10), in such a way that, in correspondence to points of contact (VI) between said series of cross strings (17A, 17B, 17D, 17E) , at least a first string (17) belonging to a first series (17A, 17D; 17B, 17E) passes alternately, above and under at least a second string (17) belonging to a second series (17A, 17D; 17B, 17E); - the stringing of an additional series of strings

(17C, 17F) arranged basically parallel or perpendicular to said axis of symmetry (Y) of the racket (10), in such a way that they intersect said series of cross strings (17A, 17B; 17D, 17E) in correspondence to vertices (VI) belonging to angles formed by effect of said cross strings (17A,

17B; 17D, 17E) and so that they are arranged, alternately, above and under said cross strings (17A, 17B; 17D, 17E) i.e. from one part and from the other of said surface determined by said frame

(11) .

13. A stringing method as in claim 12, characterised in that said two series of cross strings (17A, 17B; 17D, 17E) form angles of +50/+70 sexagesimal degrees and, especially, equal to +60 sexagesimal degrees or between +110/+130 sexagesimal degrees and, especially, equal to +120 sexagesimal degrees.

14. A stringing method as in claim 12, characterised in that each of said two series of cross strings (17A, 17B; 17D, 17E) and said additional series of strings (17C, 17F) include a number of strings (17), that determine basically parallel directions with each other.

15. A stringing method as in claim 14, characterised in that said strings (17) are fixed, by fixing means (12), to said frame (11), said fixing means (12) being appropriately shaped according to said strings' (17) directions of positioning, being variously distributed in areas

(R, S, T, U, V, Z) along said frame (11) and each basically being arranged perpendicular to a tangent at said frame (11) at a passing point of said strings (17) .