JP2001170219A - tennis racket - Google Patents

Abstract

(57) [Problem] To provide a tennis racket which has a comfortable appearance, a wide sweet area, and high strength. SOLUTION: A face portion 2C of a tennis racket 1C.
The outer peripheral edge is round, and on the inner peripheral edge, substantially linear portions 7 to 10 are provided on the face top, the face portion bottom, and the face portion side, respectively. The length of the gut stretched between the portions 7 to 10 is uniform and the sweet area is wide. In addition, since the outer periphery is round, there is no corner where stress is extremely concentrated, and the strength of the tennis racket is high. Reinforcing wires F extending in the circumferential direction are provided at four corners of the face 2C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tennis racket, and more particularly to a tennis racket having an improved inner peripheral shape of a face portion.

[0002]

2. Description of the Related Art As shown in FIG.
Generally designates a face portion 2, a shaft portion 3 and a grip portion 4.
The face portion 2 is provided with guts vertically and horizontally. Although the face portion 2 of the tennis racket 1 shown in FIG. 4 is substantially elliptical, the fifth portion shown in Japanese Utility Model Publication No.
There is also known a tennis racket 1A in which the face portion 2A is closer to a square than that in FIG.

[0003] The inventor of the present invention has conducted studies to expand the suite area of a tennis racket, and has found that it is effective to make the gut length uniform. For that purpose, it has been found that it is effective to make the face portion more square than that shown in FIG.

However, it has been found that when the face portion is made closer to a square shape than in FIG. 5, the stress at the time of hitting is concentrated near the four corner portions C, and the strength of the tennis racket becomes insufficient. Was.

Therefore, the inventor of the present invention has made the outer periphery of the face portion round as shown in FIG. 6 and provided one or two pairs of parallel portions 5 on the inner periphery.
A trial tennis racket 1B provided with was prepared, and its characteristics were measured. As a result, it was recognized that the gut length was uniformed by providing the parallel portion 5, and the sweet area was widened.

However, on the other hand, the tennis racket shown in FIG.
1B is a tennis racket whose face 2B is
Because it is quite different from the
Was found to be inferior. In addition, the face 2B
Frame thickness t ₁, T₂, T₃Is a corner
Because it changes near the part C, the ball hits near this corner part C
It was also recognized that stress at the time was concentrated.

[0007] To cope with this, the present applicant has disclosed a tennis racket having a large sweet area, little local stress concentration and high strength, as disclosed in Japanese Patent No.
No. 991129, a face portion, a shaft portion connected to the face portion, and a grip portion connected to the shaft portion, and a gut hole is provided in the face portion in a circumferential direction so as to communicate an inner peripheral edge and an outer peripheral edge. A: A plurality of tennis rackets are provided in the following manner: A: The projection shapes obtained by projecting the face portion on a plane parallel to the hitting surface are the following (A) and (B): The periphery (except for the connection between the face and the shaft) and the inner periphery are both curved curves; (b) the outer periphery (excluding the connection between the face and the shaft) and the inner periphery B: At least a part of the inner peripheral edge of the face portion extends in the center portion in the thickness direction perpendicular to the ball striking face and extends in the face portion peripheral direction. groove A tennis ball, characterized in that, in a cross section cut in parallel with the ball striking surface at a central portion in a thickness direction perpendicular to the ball striking surface, a curved portion close to a straight line as described below is provided on the inner peripheral edge of the face portion. Rackets have been proposed. It should be noted that both of these features may be provided. A portion formed by a curve closer to a straight line than an arc having a radius R of 150 mm is provided on the inner peripheral edge of the face top and the face bottom. In this case, it is preferable that the length along the inner periphery of the face portion of a portion formed by a curve that is closer to a straight line than an arc having a radius R of 150 mm is 20 to 200 mm. A portion formed by a curve closer to a straight line than an arc having a radius R of 220 mm is provided on the inner peripheral edge of both face sides. In this case, the length along the inner periphery of the face portion of a portion formed by a curve closer to a straight line than the arc having a radius R of 220 mm is 3
It is preferably from 0 to 300 mm.

In such a tennis racket, a curved portion close to the straight line is formed by providing a groove on the inner periphery of the face portion. However, in the projection shape when the face portion is projected on a plane parallel to the hitting surface, The distance between the inner peripheral edge and the outer peripheral edge is substantially equal in the circumferential direction of the face portion, and in the projected shape of the face portion, the inner peripheral edge and the outer peripheral edge have curved curves as in the related art.

For this reason, the tennis racket of the same patent is
The appearance is the same as that of the conventional product, there is no strange feeling, and it is easy for the player to use.

Also, in the tennis racket of the same patent, since the curved portion close to a straight line is provided on the inner periphery, the lengths of the guts stretched on the curved portion close to the straight line become uniform.
The sweet area becomes wider.

Furthermore, the stress is not locally concentrated on the face portion, and the strength of the tennis racket is high.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a tennis racket in which the tennis racket of Japanese Patent No. 299129 is further improved and the strength near the four corners is increased.

[0013]

SUMMARY OF THE INVENTION A tennis racket according to the present invention is a tennis racket provided with grooves extending in the circumferential direction on the inner peripheral surface of the four corners of the face portion. The present invention is characterized in that an existing reinforcing wire is provided.

Preferably, the tennis racket of the present invention
A face portion, a shaft portion connected to the face portion, and a grip portion connected to the shaft portion, wherein a plurality of gut holes are provided in the face portion at circumferential intervals so as to communicate an inner peripheral edge and an outer peripheral edge. A: A tennis racket is provided, wherein: A: the projection shape of the face portion projected on a plane parallel to the hitting surface is the following (A) and (B); , Excluding the connecting portion between the face portion and the shaft portion) and the inner peripheral edge are both curved curves; (b) between the outer peripheral edge (excluding the connecting portion between the face portion and the shaft portion) and the inner peripheral edge B: At least a part of the inner peripheral edge of the face portion is provided with a groove extending in the circumferential direction of the face portion at a central portion in the thickness direction perpendicular to the hitting surface. , Thickness perpendicular to the ball striking surface In striking face parallel to section cut at the center of the direction, the radius R to the inner peripheral edge of the face top and face Bottom 15
C: a portion formed by a curve that is closer to a straight line than an arc of 0 mm. C: At least a part of the inner peripheral edge of the face portion is provided at a central portion in a thickness direction perpendicular to the ball striking face. In a cross section cut in parallel with the hitting surface at the center in the thickness direction perpendicular to the hitting surface, a groove closer to a straight line than a circular arc having a radius R of 220 mm is provided on the inner peripheral edges of both face sides. Is provided.

In the tennis racket of the present invention, in the tennis racket of the above-mentioned Japanese Patent No. 2991129, by providing grooves near four corners, the reduced strength of the corners is supplemented by a reinforcing wire.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 3 show a tennis racket 1C according to an embodiment. The gut holes are not shown in the drawings for clarity. This gut hole is provided at the center in the thickness direction perpendicular to the hitting surface of the face portion, similarly to a conventional tennis racket. Also, as shown in FIGS. 1B, 1C and 1D, the face portion 2C of the tennis racket 1C is hollow, but for clarity of the drawing, the face portion is shown solidly in FIGS. Is shown.

The face portion 2C of the tennis racket 1C
The outer peripheral edge (excluding the connecting portion between the face and the shaft) and the inner peripheral edge when the face portion 2C is projected on a plane parallel to the hitting surface are both curved.

In this projected shape, the width (distance) t between the outer peripheral edge (excluding the connecting portion between the face portion and the shaft portion) and the inner peripheral edge is substantially uniform over the entire circumference.

The outer peripheral edge in this projected shape coincides with the outer peripheral edge of the face portion in FIG. 1 (a). The inner peripheral edge in this projected shape matches the inner peripheral edge (solid line) of the face portion in FIG.

As described above, the face portion is formed by a curved curve on both the inner and outer peripheral edges, and the width t in the projected shape is obtained.
Are uniform over the entire circumference, the appearance (external shape) is the same as that of a conventional tennis racket, and there is no apparent discomfort.

In addition, the inner peripheral edge is located at the upper left of FIG.
Grooves 6 are provided in the vicinity of the upper right, lower left and lower right corners, so that the face 2C is a cross section passing through the center of the face in the thickness direction perpendicular to the ball striking face (FIG. 2 is this cross section). On the inner periphery of the face top,
Curved portions 7, 8, 9, 10 that are nearly straight are formed on the face bottom and both face sides, respectively. The groove 6 is provided so as to gradually become deeper from the inner peripheral edge where the groove is not formed, that is, so that the bottom surface of the groove 6 smoothly continues to the inner peripheral edge of the portion where the groove 6 is not provided. ing.

As described above, since the curved portions 7 to 10 near the straight line are formed at the center in the thickness direction of the face portion, the length of the gut stretched between the curved portions 7 and 9 close to the straight line , And the length of the gut stretched between the curved portions 8, 10 which are close to a straight line,
The sweet area becomes wider.

Further, since there is no portion where the width t changes extremely in the face portion, a large stress is not locally applied to the face portion at the time of hitting a ball.

The curved portions 7, 9 which are close to the straight line of the face top and the face bottom extend in a direction substantially orthogonal to the long axis direction of the tennis racket, and the curved portions 8, 10 which are close to the straight line of the face side. It extends in a direction substantially parallel to the long axis direction.

In the present invention, the curved portions 7, 9 which are close to the face top and face bottom straight lines of the face portion 2C may be straight lines. However, due to the design of the frame, the four corners of the upper left, upper right, lower left and lower right corners are used. Since the part is unreasonable, the radius R is closer to a straight line than an arc having a radius of 150 mm. The curved portions 8, 10 that are close to the straight line on the inner periphery of the face side are lines closer to a straight line than an arc having a radius R of 220 mm.

The lengths of the curved portions 7 and 9 which are close to the straight lines of the face top and the face bottom (the length of the path along the inner periphery of the face portion) are 20 to 200 mm, preferably 50 to 1 mm.
It is 50 mm. The length of the curved portions 8, 10 close to a straight line on the face side is 30 to 300 mm, preferably 50 to 200 mm.

Although not shown, in the present invention, a curved portion close to a straight line may be provided only on both face sides. Further, a curved portion close to a straight line may be provided only on the face top and the face bottom.

When a curved portion close to a straight line is provided only on the face top and the face bottom, the sweet area becomes wide in a direction perpendicular to the longitudinal axis direction and parallel to the ball striking surface. Is provided only on both face sides, the sweet area becomes wider in the longitudinal axis direction. In addition, when provided on the face top and the face bottom and on both faces, the sweet area becomes wider in both directions.

In the present invention, the expression that the width t of the face portion is substantially uniform over the entire circumference means that the maximum value t of the width t
_max , the difference between the minimum value t _min and the width average value t ₀ is within ± 20% (preferably ± 10%) of t ₀ .

As a material of the tennis racket of the present invention,
In addition to metals (including alloys) such as aluminum and titanium, various types such as fiber-reinforced synthetic resins can be employed.

In the tennis racket 1C, reinforcing wires F extending in the circumferential direction of the face portion are provided at the four corner portions to reinforce the corner portions. As this reinforcing wire, carbon fiber, glass fiber, organic fiber, ceramic fiber, etc. are aligned, or a rope shape, aluminum, stainless steel, titanium, copper,
Tungsten, wires of these alloys and the like are suitable. The reinforcing wire may be provided with knots at predetermined intervals.

More specifically, a lottery-shaped string is suitable as the reinforcing wire. The lottery string is made of a unidirectional fiber reinforced resin (U
D prepreg) can be cut to an appropriate width and length and wound around the fiber direction as an axis. Also, among the ceramic fibers, boron fibers and the like are preferable because of their high toughness.

In recent years, since tennis rackets have tended to be lighter and have a larger face area, they are usually formed by molding a racket by an internal pressure method using a 25-ton class carbon fiber reinforced resin. By using carbon fiber reinforced resin of ton or more, the design is designed to reduce the weight of the racket and increase the rigidity of the face surface by reducing the number of laminated fiber reinforced resin (prepreg). However, carbon fibers having a high modulus of elasticity have high rigidity, so it is difficult to wind them around a tube used for internal pressure molding.
Also, when the tube is bent after being wound and set in a racket mold, there is a possibility that elastic carbon fibers having a high modulus of elasticity are apt to wrinkle and easily cause molding defects. There is. Therefore, it is difficult to form a racket using only the elastic carbon fiber having a high elastic modulus, and it is effective to use a lottery-like string for such a racket.

For the above reason, the racket mass is 200 to
It is effective to apply the present invention to a material weighing 280 g. In addition, the face area is particularly 700 to 840 cm.
It is effective to apply the present invention to a racket having a large face area of ² .

In the present invention, it is preferable that the string is disposed on the inner surface of the face portion at least partially or entirely symmetrically with respect to the groove on the inner peripheral surface side of the face portion. This lottery-shaped string is preferably 5 cm or more in order to obtain a reinforcing effect, and the thickness is 0.5 to 2.0 m in diameter.
Those having a size of about m are preferred because they are easy to handle.

Further, in the four corners of the face portion, forces in the vertical direction and the horizontal direction are applied, and in terms of shape, the curvature of the face portion is minimized and stress is extremely concentrated. The effect of using a string is great.

[0037]

EXAMPLE A tennis racket of the present invention was formed by laminating a unidirectional fiber reinforced resin having a modulus of elasticity of 25 tons and 30 tons at a ratio of 70/30, and molding by an internal pressure molding method. At this time, grooves were provided symmetrically around the grip axis in the vicinity of the four corners where the warp (gut) and the weft (gut) intersect on the inner peripheral surface of the face. The groove extends in the circumferential direction of the face portion at the center in the thickness direction perpendicular to the hitting surface.

A plurality of unidirectional carbon fiber reinforced resins (UD prepregs) having a modulus of elasticity of 25 tons are wound on the inner peripheral surface side of the face portion in a longitudinal direction, and a plurality of longitudinally oriented unidirectional carbon fiber reinforced resins are wound around the face portion. The string was arranged on the inner surface of the face portion symmetrically with respect to the groove on the inner surface side of the face portion in the longitudinal direction of the groove and over substantially the same length as the groove. Then, a comparative evaluation of the product of the present invention and conventional products A and B was performed.

Each racket has a face of 61 l.
A batt (267N) tension is applied and a tennis ball is launched from a bazooka at a speed of about 90 km / s using a bazooka for launching a tennis ball. The ball was hit by a test.

The contents of the product of the present invention used in this experiment and products A and B of other companies are as follows.

Weight Face Area Face Shape / Characteristics Invention 232g Approx. 740cm ² Round / Face Inside Groove Thick Racket Conventional Competitor A 235g 740cm ² Round Thick Racket Conventional Competitor B 237g 740cm ² Square Thick Racket Experiment Result: Invention product: No damage even after 10,000 times Conventional product A: Cracks were observed at 1 o'clock to 2:00 o'clock face after 10,000 runs. Conventional product B: Frame broken at 1 o'clock to 3 o'clock at approximately 4000 times.

[0042]

As described above, the tennis racket of the present invention has a curved portion close to a straight line on the inner periphery,
The length of the gut stretched on the curved portion close to the straight line becomes uniform, and the sweet area is wide. Moreover, the strength near the four corners is also high.

According to the present invention, a curved portion close to the straight line is formed by providing a groove on the inner periphery of the face portion, and the appearance of the face portion is the same as that of the conventional product, so that it is strange for the player. Easy to use without feeling.

In the tennis racket of the present invention, stress is not locally concentrated on the face portion, and the tennis racket has high strength.

[Brief description of the drawings]

FIG. 1A shows a tennis racket 1 according to an embodiment.
(A) is a front view, (b), (c) and (d) of FIG.
It is sectional drawing which follows the BB line, CC line, and DD line of the figure.

FIG. 2 is a sectional view of a tennis racket 1C according to the embodiment.

FIG. 3 is a main part configuration diagram of a tennis racket 1C according to the embodiment.

FIG. 4 is a front view of a tennis racket 1 according to a conventional example.

FIG. 5 is a front view of a tennis racket 1A according to a conventional example.

FIG. 6 is a front view of a tennis racket 1B showing a comparative example.

[Explanation of symbols]

 1, 1A, 1B, 1C Tennis racket 2, 2A, 2B, 2C Face part 3 Shaft part 4 Grip part 5 Linear part 6 Groove 7, 8, 9, 10 Curved part close to straight line F Reinforcement wire

Claims (2)

[Claims] 1. A tennis racket provided with grooves extending in the circumferential direction on the inner peripheral surface of the four corners of the face portion, wherein a reinforcing wire rod extending in the circumferential direction is provided at the four corners. Tennis racket. 2. The tennis racket according to claim 1, wherein the tennis racket has a face portion, a shaft portion connected to the face portion, and a grip portion connected to the shaft portion, wherein the face portion has an inner peripheral edge and an outer peripheral edge. A tennis racket in which a plurality of gut holes are provided at intervals in a circling direction so as to communicate with each other, and A: The projection shape obtained by projecting the face portion on a plane parallel to a hitting surface is as follows: (B) The outer peripheral edge (excluding the connecting portion between the face portion and the shaft portion) and the inner peripheral edge are both curved curves; (b) the outer peripheral edge (but not the face portion) The width between the inner peripheral edge and the inner peripheral edge is substantially uniform over the entire periphery; B: at least a part of the inner peripheral edge of the face portion in the thickness direction perpendicular to the hitting surface. In the center, A groove extending in the scan unit circumferentially provided, in a cross section taken parallel to the ball striking face at the center portion of the ball striking face and a thickness direction perpendicular radius R to the inner peripheral edge of the face top and face Bottom 15
C: a portion formed by a curve that is closer to a straight line than an arc of 0 mm. C: At least a part of the inner peripheral edge of the face portion is provided at a central portion in a thickness direction perpendicular to the ball striking face. In a cross section cut in parallel with the hitting surface at the center in the thickness direction perpendicular to the hitting surface, a groove closer to a straight line than a circular arc having a radius R of 220 mm is provided on the inner peripheral edges of both face sides. A tennis racket, characterized in that it has a part that is formed.