JPH10309332A - Racket frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a racket frame with which a ball is sufficiently held in case of use for a player at swing speed which is not so high, satisfactory repulsiveness and spin application characteristics can be provided, the directionality of ball is stabilized and the fluctuation of face is extremely reduced as well. SOLUTION: This racket frame 1 is made of carbon fiber reinforced synthetic resin while having a head part 2 for forming a gut face by spreading gut, shaft part 3 communicated to the head part and grip part 4 communicated to the shaft part. In this case, the carbon fibers of head part 2 and shaft part 3 are composed of low elastic modulus carbon fibers arranged in peripheral or lengthwise direction with the elastic modulus lower than 5 to 17 ton/mm<2> and middle/ high elastic modulus carbon fibers arranged in bias direction with the elastic modulus from 17 to 30 ton/mm<2> .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racket frame for hard tennis, and more particularly to a racket frame which is easy to bend, has good resilience, is strong in torsion, has good surface stability, and is excellent in spinning and controllability.

[0002]

2. Description of the Related Art As a rigid tennis racket frame,
Those made of fiber-reinforced synthetic resin are widely used. Such a fiber-reinforced synthetic resin racket frame is formed by laminating a prepreg sheet around a core material, placing the prepreg sheet in a mold frame-shaped cavity, and heating and heating the prepreg sheet (for example, see Japanese Patent Application Laid-Open No. 5-96030). No.). Carbon fibers are widely used as the fibers. The elastic modulus of this conventional carbon fiber is 20 to 30 ton / mm ² .

[0003]

The conventional racket frame can make the ball hit with sufficient bending for a hard hitter having a high swing speed, but can be used for a general player whose swing speed is not so high. Difficult to hit a satisfactory ball. That is, the ball has poor resilience and does not easily spin the ball.

[0004] In order to increase the flexibility of the racket frame and improve the resilience and spin imparting property, it is conceivable to use about 20 to 60% of glass fiber as a fiber. As the strength decreases, the torsion of the racket frame increases, and the surface stability of the racket frame deteriorates. Further, when glass fiber is blended, there is a disadvantage that the vibration damping property of the racket frame is deteriorated and the weight of the racket frame is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve such a drawback, and provides a racket frame which is easy to bend, has high resilience, is resistant to torsion, has good surface stability, and has excellent spin characteristics and controllability. The purpose is to provide.

[0006]

According to a first aspect of the present invention, there is provided a racket frame comprising: a head portion for extending a gut to form a gut surface; a shaft portion connected to the head portion; and a grip portion connected to the shaft portion. In a racquet frame made of a carbon fiber reinforced synthetic resin having the following characteristics, at least a part of the carbon fibers is 5 ton / mm ² or more and 17 ton /
It is a carbon fiber having a low elastic modulus (tensile elastic modulus) of less than ² mm ² .

According to a second aspect of the present invention, there is provided a racket frame comprising: a head portion for extending a gut to form a gut surface; a shaft portion connected to the head portion; and a grip portion connected to the shaft portion. In a racquet frame made of a reinforced synthetic resin, at least a part of carbon fibers of the head portion extending in a direction of 0 to 20 ° with respect to a circumferential direction of the head portion has an elastic modulus of 5 t.
It is a carbon fiber having a low elastic modulus (tensile elastic modulus) of on / mm ² or more and less than 17 ton / mm ² .

A racket frame having a head portion in which carbon fibers having a low modulus of elasticity are distributed in the circumferential direction as described above has a large bending deformation of the head portion when hitting a ball even when used by a general player, and provides high rebound. .

According to a third aspect of the present invention, there is provided a racket frame made of carbon fiber reinforced synthetic resin having a head portion which extends a gut to form a gut surface, a shaft portion connected to the head portion, and a grip portion connected to the shaft portion. In at least one of the carbon fibers of the shaft portion, at least a part of the carbon fibers extending in a direction of 0 to 20 ° with respect to the longitudinal direction of the shaft portion has an elastic modulus of 5 ton / m.
It is a carbon fiber having a low elastic modulus of not less than m ^{2 and} less than 17 ton / mm ² .

A racket frame having a shaft portion in which carbon fibers having a low modulus of elasticity are distributed in the longitudinal direction as described above has a large amount of bending of the shaft when hitting a ball even when used by a general player. Provides high resilience.

In the present invention, it is preferable that the elastic modulus of the carbon fiber extending in the bias direction of 25 ° or more with respect to the circumferential direction or the longitudinal direction of the racket frame is 17 to 50 ton / mm ² . In the present invention, it is preferable that the flexure amount of the racket frame be 10 to 30 mm when the base end of the grip portion is fixed and a load of 6 kg is applied to the distal end of the racket frame in a direction perpendicular to the gut surface and measured. Such a racket frame is suitable for a general player to bend.

[0012]

Embodiments of the present invention will be described below in more detail.

FIG. 1A is a front view of a racket frame 1 according to an embodiment, and shows a head portion 2 and a shaft portion 3.
The grip 4 and the grip 4 are both made of carbon fiber reinforced synthetic resin. The head section 2 corresponds to B- in FIG.
As shown in FIG. 1 (b), which is a cross-sectional view along the line B, the cross-sectional shape in a direction perpendicular to the gut surface and toward the center of the head (centripetal direction) is substantially rectangular, so that the hoop is easily deformed. ing. The head portion 2 has a gut insertion hole 2a.
Are provided in the centripetal direction, and the gut is stretched through the grommet.

The shaft portion 3 has a double yoke structure having a bridge 6 extending in a direction perpendicular to the axial direction of the racket frame, and the torsional rigidity of the shaft portion 3 is enhanced.

Next, the amount of bending and twisting of the racket frame will be described.

I The amount of bending deflection The amount of bending deflection of the racket frame 1 is such that the base end of the racket frame 1 is fixed over a range of 150 mm as shown in FIG. Bending displacement W of the tip when P is applied
(Mm).

In the present invention, the amount of bending deflection is 10
If it is smaller than mm, the racket frame is too hard for an ordinary player, resulting in poor hitting feeling and swinging feeling. If the amount of bending is larger than 30 mm, the racket frame becomes excessive during the swing, and the directionality of the ball is not stabilized.

II Twist Angle As shown in FIG. 3 (a view of the racket viewed from the front end to the rear end), the racket frame is cantilevered, and a load of 6 kg is applied to the maximum width of the head in a direction perpendicular to the gut surface. The twist angle θ generated at this time is measured.

The twist angle θ is preferably 1 to 2 °. θ
Is smaller than 1 °, the shot feeling becomes too hard, and the impact transmitted to the hand at impact becomes large. Conversely, if the torsion angle θ is larger than 2 °, the face is likely to blur when the ball hits.

As described above, in this embodiment, the torsional rigidity of the shaft is increased by forming the shaft in a double yoke structure.

The racket frame of the present invention, although being made of carbon fiber reinforced plastic, at least in part a tensile modulus of the carbon fibers is 5 ton / mm ² or more 17ton / mm ² preferably less than 5 ton / mm ^Two
More than 9 ton / mm ^{2 and} especially 6 to 8 ton / mm
It is a carbon fiber with a low elastic modulus of ² .

It is preferable that the low-modulus carbon fiber is distributed so as to extend in a direction of 0 to 20 ° with respect to a circumferential direction of the head portion (a direction around the outer periphery of the gut surface) in the head portion.

By arranging carbon fibers having a low elastic modulus in the circumferential direction in this manner, the bending of the head portion is increased, and a large rebound can be obtained even when used by a general player.

According to the present invention, the angle of 25
17 to 50 ton / mm ^2, especially 30 to 40 so as to extend in the bias direction of not less than 25 ° (ie, 25 to 90 °).
It is preferable to distribute carbon fibers having a medium / high elastic modulus of ton / mm ² .

As described above, the low elastic modulus carbon fibers are used in the circumferential direction, and the medium and high elastic modulus carbon fibers are distributed in the bias direction of 25 ° or more with respect to the circumferential direction. The strength can be made sufficiently high, and the torsion of the head portion can be reduced to improve the surface stability.

In the present invention, it is preferable that the low elastic modulus carbon fibers are distributed in the shaft portion so as to extend in a direction of 0 to 20 ° with respect to the longitudinal direction of the shaft portion.

By arranging carbon fibers having a low modulus of elasticity in the longitudinal direction of the shaft portion, the bending of the shaft portion is increased, and a large rebound can be obtained even when used by a general player. .

According to the present invention, 17 to 50 ton / mm ^2, especially 30 to 90 tons, extends in the bias direction of 25 ° or more (ie, 25 to 90 °) with respect to the longitudinal direction of the shaft portion.
It is preferable to distribute carbon fibers having a medium / high elastic modulus of 40 ton / mm ² .

As described above, the low elastic modulus carbon fibers are used in the longitudinal direction, and the medium and high elastic modulus carbon fibers are distributed in the bias direction of 25 ° or more with respect to the longitudinal direction. The strength can be made sufficiently high, and the torsion of the shaft portion can be reduced to improve the surface stability.

As the synthetic resin blended with the carbon fiber, epoxy resin, nylon and the like are preferable.
Epoxy resins are preferred in terms of strength, durability and price.

In order to manufacture the racquet frame of the present invention, a plurality of prepreg sheets are laminated around a core material, the prepreg sheets are placed in a cavity in the shape of a mold frame, and heated. A normal method of manufacturing a frame may be used.

By changing the amount and orientation direction of carbon fiber in the prepreg sheet and the tensile modulus,
The elastic modulus of the carbon fiber reinforced synthetic resin can be changed.

FIG. 4 (a) is a diagram showing the arrangement of prepreg sheets suitable for producing the racket frame of the present invention and the configuration in the fiber orientation direction.

In the example of FIG. 4 (a), the fibers are all carbon fibers, and the first to fifth prepreg sheets 11 to 15 are laminated from the inner layer side. Each prepreg sheet is laminated on the core material 20 as shown in FIG.
It has a racket frame shape. 0,800 in FIG.
Indicates the distance (the distance along the frame) from the tip of the head portion (unit: mm).

Pre-preg sheet 1 of second and third layers
2 and 13 show that the elastic modulus of the carbon fiber is 5 ton / mm ^2.
It is less than 17 ton / mm ² and the orientation directions of the carbon fibers are all within 20 ° with respect to the longitudinal direction of the prepreg sheet. The elastic modulus of the carbon fibers of the prepreg sheets 11, 14, and 15 of the first layer, the fourth layer, and the fifth layer is 17 to 50 ton / mm ² , and the orientation of these carbon fibers is each prepreg. It is at least 25 ° with respect to the longitudinal direction of the sheets 11, 14, and 15.

In each of the prepreg sheets 11 to 15,
The proportion of the carbon fiber in the total amount of the carbon fiber and the synthetic resin is preferably 45 to 75% by weight, particularly preferably 55 to 65% by weight.

The head portion and the shaft portion include the prepreg sheets 12 and 13 of the low-modulus carbon fibers having a fiber orientation angle of 20 ° or less (preferably, an orientation angle of 0 °), so that the head portion and the shaft portion are formed. It becomes easy to bend. The amount of the prepreg sheets 12 and 13 containing carbon fibers having an orientation angle of 20 ° or less in the head portion and the shaft portion should be 15% by weight or more, especially 20% by weight or more of the prepreg sheets in the head portion and the shaft portion. preferable. If the amount of the prepreg sheets 12 and 13 is too large, the torsional rigidity is reduced.
The amount of the following prepreg sheets 12, 13 is preferably 36% by weight or less, particularly preferably 30% by weight or less.

In the present invention, a part of the medium and high modulus carbon fibers distributed in the bias direction may be replaced with boron fiber, aramid fiber (trade name) or the like.

[0039]

EXAMPLE The prepreg sheets 11 to 15 shown in FIG. 4 were laminated to produce a racket frame 1 having the shape shown in FIG. Table 1 shows the width, length, and amount of the prepreg sheets 11 to 15. The elastic modulus of the carbon fibers in the second and third layers is 8 ton / mm ² .
The elastic modulus of the four or five-layer carbon fiber is 24 ton / mm ²
The resin of the prepreg sheet is an epoxy resin.

The orientation angle of the carbon fibers with respect to the longitudinal direction of the prepreg sheet is 45 ° for the first layer, 0 ° for the second and third layers, 45 ° for the fourth layer, and 30 ° for the fifth layer.
It is. The content of carbon fibers in each of the prepreg sheets 11 to 15 is 55% by weight.

[0041]

[Table 1]

The racket frame 1 had a bending deflection of 15 mm and a twist angle of 1.5 degrees.

The racket frame 1 was very popular with intermediate-level testers (student players) whose swing speed was not so high, and all of them had extremely good resilience, spin imparting property and directionality.

[0044]

As described above, the racket frame of the present invention can provide good resilience and spin imparting characteristics when used by a player whose swing speed is not so high. Further, in this racket frame, the directionality of the ball is stable and the fluctuation of the surface is extremely small.

[Brief description of the drawings]

FIG. 1A is a front view showing a racket frame according to an embodiment, and FIG. 1B is a cross-sectional view taken along line BB in FIG. 1A.

FIG. 2 is an explanatory diagram of measurement of bending rigidity.

FIG. 3 is an explanatory diagram of measurement of twist.

FIG. 4 is an explanatory diagram of fiber orientation of a prepreg.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Racket frame 2 Head part 3 Shaft part 4 Grip part 11-15 Prepreg 20 Core metal

Claims (5)

[Claims] A racquet frame made of carbon fiber reinforced synthetic resin having a head portion that stretches a gut to form a gut surface, a shaft portion connected to the head portion, and a grip portion connected to the shaft portion. At least a part of the fiber is 5 ton / mm ² or more and 17 ton /
A racket frame characterized by low elastic modulus carbon fibers of less than mm ² . 2. A racquet frame made of carbon fiber reinforced synthetic resin, comprising: a head portion to which a gut is stretched to form a gut surface; a shaft portion connected to the head portion; and a grip portion connected to the shaft portion. 0 to 20 ° with respect to the circumferential direction of the head portion of the carbon fibers in the head portion
Wherein at least a portion of the carbon fibers extending in the direction of (b) are low elastic modulus carbon fibers having an elastic modulus of 5 ton / mm ² or more and less than 17 ton / mm ² . 3. A racquet frame made of carbon fiber reinforced synthetic resin, comprising: a head portion which extends a gut to form a gut surface; a shaft portion connected to the head portion; and a grip portion connected to the shaft portion. Of the carbon fibers in the shaft portion, 0 to the longitudinal direction of the shaft portion
A racket frame characterized in that at least a part of the carbon fibers extending in the direction of 20 ° are low elastic modulus carbon fibers having an elastic modulus of 5 ton / mm ² or more and less than 17 ton / mm ² . 4. An elastic modulus of carbon fibers extending in a bias direction of 25 ° or more to a circumferential direction or a longitudinal direction of a racket frame according to claim 2 or 3, wherein the elastic modulus of the carbon fibers is 17 to 50 tons.
A racket frame characterized by n / mm ² . 5. The racket frame according to claim 1, wherein a base end of the grip portion is fixed, and a load of 6 kg is applied to a tip of the racket frame in a direction perpendicular to a gut surface. The racket frame has a bending deflection of 10 to 30 m
m. A racket frame characterized by m.