WO2012126896A1

WO2012126896A1 - String used for stringing all or part of a tennis racket, stringed tennis racket and associated stringing method

Info

Publication number: WO2012126896A1
Application number: PCT/EP2012/054829
Authority: WO
Inventors: Olivier HURET
Original assignee: Huret Olivier
Priority date: 2011-03-24
Filing date: 2012-03-19
Publication date: 2012-09-27
Also published as: FR2972937A1

Abstract

The invention relates essentially to a string (1, 1') for a tennis racket, characterized in that it has a section (S, S') along a transverse section formed by: - first sides (4.1, 4.1') having a radius (R1, R1') of curvature of 1.15 cm plus or minus 0.10 cm, and - second sides (4.2, 4.2') having a radius (R2, R2') of curvature of 0.20 cm plus or minus 0.15 cm, - the first sides (4.1, 4.1') being connected together by means of the second sides (4.2, 4.2').

Description

ROPE USED FOR THE ROPE OF ALL OR PART OF A TENNIS RACKET (S), TENNIS RAQUETTE ROPED AND

ASSOCIATED CORDING METHOD

[01] TECHNICAL FIELD OF THE INVENTION [02] The invention relates to a rope used for the stringing of all or part of the tennis racquet (s), the tennis racket stringed with a rope made from said string, and than the associated stringing process.

[03] It is recalled that a rope consists of a rope of a given length to string a tennis racket for example of the order of 12m (usual length marketed for a classic racket). A rope may also be made of two half-ropes having for example each a length of 6.5m.

[04] STATE OF THE ART

[05] The breaking of a string in the sieve corresponding to the inner part of the frame of a tennis racket is the main cause causing the players to change the entire string of their tennis racket.

[06] This phenomenon is all the more marked as the player has a technique that leads to a powerful ball shot with effects transmitted to the ball. Indeed, the strings present in the sieve wear as and when the use of the racket by the player.

[07] A rope is formed by strings stretched in a longitudinal direction of the racket called "uprights" and ropes stretched in a direction transverse to the longitudinal direction of the racket called "through". [08] The shear then the breaking of the ropes are the consequence of the friction between the amounts and the transverses, mainly caused by the lateral movement of the amounts on the transverses.

[09] Indeed, with each strike, the friction causes an overheating of the points of contact of the amounts with the traverses, which provokes progressively the wear of the contact points, weakens the ropes and then causes the rupture of the rope.

[010] To counter this effect, the ropes consist of a protective layer over their entire outer surface, so that the coefficient of friction between the ropes is minimal.

[011] As long as this layer remains intact, the rope does not shear. On the other hand, as soon as this layer is pierced, the rope started undergoes a heating which causes its melting then its fast break.

[012] The smaller the contact area between the cords, the faster the shearing takes place.

[013] OBJECT OF THE INVENTION

The object of the invention is to propose a form of rope that considerably increases the contact surface between the ropes and makes it possible in particular to increase the duration of the rope. [015] For this purpose, the invention relates to a tennis racket string, characterized in that it has a section in a cross section delimited by:

first sides having a radius of curvature of 1.15 cm plus or minus 0.10 cm, and

- second sides having a radius of curvature of 0.20cm plus or minus 0.15cm,

the first sides being interconnected via the second sides,

- the section being delimited

or by three first sides interconnected by three second sides so as to have the general shape of a triangle with convex rounded corners and sides, the sides of the triangle being formed by the first sides while the rounded corners of the triangle are formed by the second sides,

- or by four first sides interconnected by four second sides so as to have the general shape of a square at angles and sides rounded convex, the sides of the square being formed by the first sides while the rounded corners of the square are formed by the second sides.

[016] In one embodiment, the rope has a weight per meter of 1.60 grams plus or minus 0.15 grams. [017] In one embodiment, for the shape of a triangle with rounded sides,

the radius of curvature of the first side is approximately 10 times greater than the average diameter of the rope,

the radius of curvature of the second side is approximately 10 times smaller than the average diameter of the rope,

the average diameter of the rope having a section having the general shape of the triangle is that of the round section rope having the same weight of material for a length of 1 m of rope.

[018] In one embodiment, for the shape of a triangle with rounded sides,

the first sides have a radius of curvature of 1 .15 cm plus or minus 0.10 cm, and

the second sides have a radius of curvature of 0.10 cm plus or minus 0.05 cm.

[019] In one embodiment, for the shape of a triangle with rounded sides, the distance of a segment passing through the center of the section connecting:

- on the one hand the center of a first side and

- on the other hand the center of a second side,

worth 1 .25mm plus or minus 0.03mm.

[020] According to one embodiment, for the shape of a square with rounded sides,

the radius of curvature of the second side is approximately 4 times smaller than the average diameter of the rope,

[021] According to one embodiment, for the shape of a square with rounded sides, the first sides have a radius of curvature of 1 .15 cm plus or minus 0.10 cm and

the second sides have a radius of curvature of 0.30 cm plus or minus 0.05 cm. [022] In one embodiment, for the shape of a square with rounded sides, the length of a segment passing through the center of the section of the connecting rope

- on the one hand the center of a first side and

- the center of a first opposite side

is worth 1.20mm plus or minus 0.07mm. [023] According to one embodiment, the rope is made in whole or part of copolymer, copolyester, or polyester.

[024] The invention further relates to a tennis racket strung with a rope made from a rope according to the invention.

[025] The invention further relates to a method of stringing amounts and skew of a sieve of a tennis racket using a rope according to the invention, characterized in that it comprises the steps following:

- perform the installation of the amounts by applying a constant voltage on each amount having a value of the order of 15% lower than a target average voltage of all the string laid in the sieve, this constant voltage on each amount being applied during at least five seconds,

- perform the laying of the cross-sections by applying a constant tension on each cross-section having a value of the order of 15% lower than the average target tension of all the rope laid in the sieve minus one kilogram, this constant tension on each amount being applied for at least twenty seconds.

[026] According to one implementation, the method comprises the step of using a rope having a rounded triangular section in the uprights and a rope having a rounded square section in the transverse. [027] According to one implementation, for a target average voltage of 22 kilograms, a voltage of 19 is applied using a stringing machine. kilograms in the amounts, and a tension of 18 kilograms in the crossings.

[028] BRIEF DESCRIPTION OF THE FIGURES

[029] The invention will be better understood on reading the description which follows and on examining the figures that accompany it. These figures are given for illustrative but not limiting of the invention. They show :

[030] Figure 1a: a 3D view of a rope having a generally triangular section with rounded corners and sides; [031] Figure 1 b: a detailed schematic representation of the section of the rope of Figure 1a;

[032] Figure 2a: a 3D view of a rope having a section of generally square shape with rounded corners and sides;

[033] Figure 2b: a detailed schematic representation of the section of the rope of Figure 2a;

[034] Figure 3: a comparative table of the applied voltage values and the duration of application of these voltages for a conventional stringing process and for a stringing method according to the invention.

[035] The identical elements retain the same reference from one figure to another.

[036] DESCRIPTION OF EXAMPLES OF EMBODIMENT OF THE INVENTION

[037] Figure 1a shows a monofilament cord 1 used for the stringing of all or part of a tennis racket. This rope 1 has a shell 2 with smooth faces delimiting the volume of the rope. This envelope 2 is preferably covered with a protective layer (not shown) to minimize the rate of friction at the intersections of the uprights and the crosses in a strung racket. In one example, this Rope 1 is made wholly or partly of copolymer, copolyester, or polyester.

[038] This rope 1 has a weight per meter of 1.60 grams plus or minus 0.15 grams. This is equivalent to a string having a round section of 1.25mm in average diameter plus or minus 0.07mm. The average diameter of a rope of any section is that of the corresponding round section rope having the same weight of material for a length of 1 m of rope.

[039] Figure 1 has shown a section S of the rope shown in more detail in Figure 1b. This section S corresponding to the profile is a cross section corresponding to the intersection between the chord 1 and the plane P perpendicular to the direction D.

[040] As clearly visible in Figure 1b, the section S is formed by three first convex sides 4.1 delimited by 5.1, 5.2 ends. These first sides 4.1 are preferably of equal length. The first sides 4.1 have a radius of curvature R1 of the order of 1 .15cm plus or minus 0.10cm. This radius R1 is associated as shown for one of the sides 4.1 to a circle of center 01. R1 being about 10 times larger than the average diameter of the rope 1, the center 01 would be outside of Figure 1b if the scale had been respected.

[041] These first sides 4.1 are interconnected by three second convex sides 4.2 delimited by ends 6.1, 6.2. These second sides 4.2 are preferably of equal length. The second sides 4.2 have a radius of curvature R2 of the order of 0.10cm plus or minus 0.05cm. This radius of curvature R2 is associated for example as shown for one of the sides 4.2 to a center circle 02. R2 is about 10 times smaller than the average diameter of the rope 1.

[042] The ends 5.1, 5.2 of the first sides 4.1 and the ends 6.1, 6.2 of the second sides 4.2 are combined at one point. The first sides 4.1 and the second sides 4.2 meet at the tangent point of the two curves (whose sides 4.1, 4.2 are derived). There is an alternation of first 4.1 and second sides 4.2 so that the section S has the general shape of a triangle with rounded corners and sides. The sides of the triangle are formed by the first sides 4.1 while the rounded corners of the triangle are formed by the second sides 4.2.

[043] The distance D1 of the segment 9 passing through the center C1 of the section S and connecting on the one hand the center C2 of a first side 4.1 and secondly the center C3 of a second side 4.2 is 1. 25mm plus or minus 0.03mm.

[044] The A1 vertex angle C1 and passing through the center of two adjacent first sides is of the order of 120 degrees plus or minus 5 degrees given the size of the first 4.1 and second 4.2 sides.

[045] Figure 2a shows a rope 1 'used for the rope of all or part of a tennis racket. This rope 1 'has an envelope 2' delimiting the volume of the rope 1 '. This envelope 2 'is preferably covered with a protective layer (not shown) to minimize the rate of friction at the intersections of the uprights and the ribs in a strung racket. In one example, this rope 1 'is made wholly or partly of copolymer, copolyester, or polyester.

[046] As before, this rope 1 'has a weight per meter of 1.60 grams plus or minus 0.15 grams. This is equivalent to a string having a round section of 1.25mm in average diameter plus or minus 0.07mm. The average diameter of a rope of any section is that of the corresponding round section rope having the same weight of material for a length of 1 m of rope. [047] Figure 2a shows a section S 'of the rope shown in more detail in Figure 1b. This section S 'corresponding to the profile is a cross section corresponding to the intersection between the chord 1' and the plane P perpendicular to the direction D '.

[048] As clearly visible in Figure 2b, the section S 'is formed by four first convex sides 4.1' delimited by ends 5.1 ', 5.2'. These first sides 4.1 'are preferably of equal length. The first ones sides 4.1 'have a radius of curvature R1' of the order of 1 .15cm plus or minus 0.10cm. This radius R1 'is associated as shown for one of the sides 4.1' to a circle of center O '. R1 'being about 10 times larger than the average diameter of the rope 1, the center O' is outside of Figure 2b if the scale had been respected. Note that the radius R1 and the radius R1 'are identical.

[049] These first sides 4.1 'are interconnected by four second convex sides 4.2' delimited by ends 6.1 ', 6.2'. These second sides 4.2 'are preferably of equal length. The second sides 4.2 'have a radius of curvature R2' of the order of 0.30cm plus or minus 0.05cm. This radius of curvature R2 'is associated for example as shown for one of the sides 4.2' to a center circle 02. R2 'is about 4 times smaller than the average diameter of the rope 1'.

[050] The ends 5.1 ', 5.2' of the first sides 4.1 'and the ends 6.1', 6.2 'of the second sides 4.2' are merged into one point. The first sides 4.1 'and the second sides 4.2' meet at the tangent point of the two curves (whose sides 4.1 ', 4.2' are derived). There is an alternation of first 4.1 'and second sides 4.2' so that the section S 'has the general shape of a square with rounded corners and sides. The sides of the square are formed by the first sides 4.1 'while the rounded corners of the square are formed by the second sides 4.2'.

[051] The distance D1 'of the segment 9' passing through the center C1 'of the section S' and connecting on the one hand the center C2 'of a first side 4.1' and on the other hand the center C3 'd' a first side 4.1 'opposite is 1 .20mm plus or minus 0.07mm.

[052] The angle A1 'of vertex C1' and passing through the center of two adjacent first sides 4.1 'is of the order of 90 degrees plus or minus 5 degrees given the size of the first 4.1' and second 4.2 ' sides. [053] The invention is not limited to only triangle and square shapes but covers any shape of section formed by first sides having a radius of curvature of 1 .15 cm plus or minus 0.10 cm and second sides having a radius of curvature of 0.20cm plus or minus 0.15cm, the first sides being interconnected through the second sides. For example, from these two types of sides, it will be possible to form sections having between 5 and 8 sides. [054] Compared to a conventional method of stringing a tennis racket, the object of the invention is to avoid over-elongation of the ropes and to minimize the loss of tension on the uprights and the skews, as is summarized in the table in Figure 3.

[055] Indeed, in conventional methods, reference is made to the tension applied by the stringing machine instead of referring to a mean tension of all the strings (uprights and through in the sieve). For an applied tension of X kilograms by the stringing machine following a voltage application time of the order of two seconds per string, an average tension obtained in the racket of X-15% and more specifically of the order of X-10% in the amounts and X-33% in the sidelines. Note also that the application time of the machine tension in a racket is on average of the order of one minute.

[056] The impact of conventional methods has the effect of a significant progressive loss of tension over the life of the rope, already at least 10% after the first hour of play. The inability to properly hold the tension applied to the rope is caused by the over-stretching of the tensioned rope during laying, especially for monofilament ropes, which by definition have a very low elasticity rate (less than two percent).

[057] The purpose of the rope laying method according to the invention is to overcome these drawbacks of loss of tension and loss of elasticity for monofilament ropes. To this end, in the invention, to obtain a target average voltage close to X-15% in the racket, a voltage is applied in the amount of X-25% for a determined duration of about five seconds and a voltage in crosswise X-25% -1 kilogram for a specified period of at least twenty seconds.

[058] This will have the effect of applying a constant voltage in each through with a loss reduced to 10% of the applied voltage and allow an increase of the average voltage of 15% in the amounts by deviation of said amounts. Indeed, during the establishment of the cross, the course of amounts is thus extended to go from one end to the other of the sieve. In addition, the rounded triangular and / or rounded square shape of the rope according to the invention makes it possible to optimize the effect of increasing the tension of the uprights. The total time of application of the constant voltage on all the strings is of the order of eight minutes, a duration eight times longer than in conventional methods.

[059] Thus, by applying lower voltages than in conventional methods for a much longer period, preserves the little natural elasticity in the monofilament strings with the following consequences: stability of the tensile strength by the strings, increase of the power at the striking of the ball, the effective life of the ropes, and improvement of playability. [060] The following is a description of a preferred implementation of the rope method according to the invention:

[061] It is first carried out laying the amounts by applying a constant voltage on each amount having a value of the order of 15% below the target voltage of the entire string laid in the sieve. This constant voltage on each amount is applied for at least five seconds. For example, for a target average voltage of 22 kilograms, a tension of 19 kilograms is applied which will increase with the installation of the crossings. Preferably, the cord having a rounded triangular section in the uprights is used. [062] is carried in a second time laying crosses by applying a constant voltage on each through having a value of the order of 15% below the target voltage of the entire string laid in the sieve minus one kilogram . This constant voltage on each amount is applied for at least twenty seconds. For example, for the aforementioned average target voltage of 22 kilograms, a voltage of 19-1 = 18 kilograms is applied. Preferably, the rope having a rounded square section is used in the ribs.

Claims

1. Rope (1, 1 ') for a tennis racket, characterized in that it has a section (S, S') in a cross-section delimited by:

first sides (4.1, 4.1 ') having a radius (R1, R1') with a curvature of 1 .15 cm plus or minus 0.10 cm, and

second sides (4.2, 4.2 ') having a radius (R2, R2') of curvature of 0.20cm plus or minus 0.15cm,

the first sides (4.1, 4.1 ') being connected to one another via the second sides (4.2, 4.2'),

- the section (S) being delimited

- or by three first sides (4.1) interconnected by three second sides (4.2) so as to have the general shape of a triangle with convex rounded corners and sides the sides of the triangle being formed by the first sides (4.1) while that the rounded angles of the triangle are formed by the second sides (4.2),

- or by four first sides (4.1 ') interconnected by four second sides (4.2') so as to have the general shape of a square with convex rounded corners and sides, the sides of the square being formed by the first sides ( 4.1 ') while the rounded corners of the square are formed by the second sides (4.2').

2. Rope according to claim 1, characterized in that the rope (1, 1 ') has a weight per meter of 1.60 grams plus or minus 0.15 grams.

3. Rope according to claim 1 or 2, characterized in that for the shape of a triangle with rounded sides,

the radius of curvature (R1) of the first side (4.1) is approximately 10 times greater than the average diameter of the rope (1),

the radius of curvature (R2) of the second side (4.2) is approximately 10 times smaller than the average diameter of the rope (1),

- The average diameter of the rope (1) having a section having the general shape of the triangle is that of the round section rope having the same weight of material for a length of 1 m of rope.

4. Rope according to one of claims 1 to 3, characterized in that for the shape of a triangle with rounded sides,

the first sides (4.1) have a radius of curvature (R1) of 1 .15 cm plus or minus 0.10 cm, and

the second sides (4.2) have a radius of curvature (R2) of

0.10cm plus or minus 0.05cm.

5. Rope according to one of claims 1 to 4, characterized in that, for the shape of a triangle with rounded sides, the distance of a segment (9) passing through the center (C1) of the section (S ) linking:

on the one hand the center (C2) of a first side (4.1) and

on the other hand the center (C3) of a second side (4.2),

worth 1 .25mm plus or minus 0.03mm.

6. Rope according to claim 1, characterized in that for the shape of a square with rounded sides,

the radius of curvature (R1 ') of the first side (4.1') is approximately 10 times greater than the average diameter of the rope (1 '),

the radius of curvature (R2 ') of the second side (4.2') is approximately 4 times smaller than the average diameter of the rope (1 '),

- The average diameter of the rope (1 ') having a section having the general shape of the triangle is that of the round section rope having the same weight of material for a length of 1 m of rope.

7. Rope according to claim 1 or 6, characterized in that for the shape of a square with rounded sides,

the first sides (4.1 ') have a radius of curvature (R1') of 1.15cm plus or minus 0.10cm and

the second sides (4.2 ') have a radius of curvature (R2') of 0.30cm plus or minus 0.05cm.

8. Rope according to one of claims 1, 6, or 7, characterized in that, for the shape of a square with rounded sides, the length of a segment (9 ') passing through the center (C1') of the section (S ') of the connecting rope (1')

on the one hand the center (C2 ') of a first side (4.1') and - the center (C3 ') of a first side (4.1') opposite

is worth 1.20mm plus or minus 0.07mm.

9. Rope according to one of claims 1 to 8, characterized in that it is made in whole or part of copolymer, copolyester, or polyester.

Tennis racket stringed with rope made from a rope according to one of claims 1 to 9.

1 1. Method for stringing strings and skewers of a sieve of a tennis racket using a rope according to one of claims 1 to 19, characterized in that it comprises the following steps:

12. The method of claim 1 1, characterized in that it comprises the step of using a rope having a rounded triangular section in the uprights and a rope having a rounded square section in the transverse.

13. The method of claim 1 1 or 12, characterized in that for a target average voltage of 22 kilograms, is applied with a stringing machine a voltage of 19 kilograms in the amounts, and a voltage of 18 kilograms in the gaps.