JPH11262545A - Badminton racket shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the strength of a badminton racket shaft without changing rigidity and to enable the racket shaft to generate a flexible bending as designed by laminating a fiber-reinforced layer comprising reinforcing fiber with tensile elasticity within a specific range and a fiber-reinforced resin layer comprising reinforcing fiber with a specific tensile elasticity value. SOLUTION: The shaft of a badminton racket is constituted of a bias layer 7 and a straight layer 6. The bias layer 7 is made of fiber-reinforced resin layer comprising reinforcing fiber with 200-400 GPa of tensile elasticity and is formed by winding two bias prepreg sheets several times around a mandrel. On the other hand, the straight layer 6 is constituted of a fiber reinforced resin layer comprising reinforcing fiber with tensile elasticity lower than 60 GPa and is similarly formed by winding two straight prepreg sheets. As the reinforcing fiber with tensile elasticity within the range 200-400 GPa, carbon fiber is most preferable since it is light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightweight and durable badminton shaft.

[0002]

2. Description of the Related Art When a badminton racket (hereinafter simply referred to as a racket) is swung, a shaft of the racket bends, and the bending causes the shuttlecock to fly farther. That is, in the performance of the racket, bending of the shaft is one of the important requirements. Also, in the racket, for example, even if the rigidity design of the shaft is the same, depending on the bending method, that is, the difference in which position becomes the best, the ball muscle of the shuttlecock and the feeling at the time of impact, etc. different. This difference in bending is called tone, and the most flexible part is called a kick point, which is an important design element together with the rigidity design (flexible design) of the shaft itself.

[0003] The condition of the kick point in the vicinity of the tip of the shaft at the time of swing is referred to as a leading racket, and the condition of the kick point in the vicinity of the base end of the shaft is referred to as a hand position racket. In. Since the tone is one of the important items representing the character of the shaft, it is an important item both in designing a racket and in selecting a racket by a player. Usually, in designing the rigidity of the shaft, the shaft made of a hollow pipe is formed into a tapered shape. In the case of an FRP shaft, the shaft rigidity is appropriately selected and designed by selecting the grade of the reinforcing fiber used and its orientation angle. Is determined, and by combining the various reinforcing fibers, or by appropriately selecting and arranging their arrangement positions and the like,
A tone is given to the shaft, and a racket having a desired tone is obtained when the shaft is assembled.

[0004]

As described above, bending is an important requirement in a racket, and therefore, bending of a shaft exhibiting the bending is also important. Recently, many lightweight rackets having a total weight of the racket frame of 95 g or less have been seen, but in order to reduce the weight, the weight of the shaft must also be reduced.
Therefore, in the shaft made of FRP, for example, by using a fiber reinforced resin sheet made of a reinforced fiber having higher elasticity than that conventionally used, the number of laminations is reduced, and the weight is reduced.

[0005] However, by doing so, the weight can be reduced and the rigidity can be satisfied. On the other hand, it is difficult to provide the flexibility, and
It is easy to have insufficient strength. For example, the base portion of the shaft where stress is concentrated has insufficient strength and must be reinforced with a separate reinforcing material. Although sufficient strength is achieved if the reinforcement is sufficiently reinforced, the weight is increased by that amount, making it impossible to reduce the weight, and the rigidity tends to be larger than the set value.

Particularly, in a hand-held racket, the vicinity of the base end of the shaft, which is a part close to the grip end of the shaft, is most likely to bend, but the base end of the shaft is also loaded on the shaft at the time of hitting the ball. Since it is a place where stress concentrates, it is necessary to partially provide a reinforcing layer. Therefore, the portion necessarily has high rigidity. That is, even if the rigidity of the base end of the shaft is designed to be low in order to make it at hand, in response to the concentration of stress applied to the base end of the shaft, if a reinforcing material for improving strength is used, The rigidity increased with the strength, and it was difficult to obtain an ideal hand-held racket.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a badminton racket shaft which is lightweight, has improved strength without significantly changing the rigidity, and has the designed flexibility and excellent durability. .

[0008]

In order to achieve the above-mentioned object, the invention according to claim 1 has a tensile modulus of 200 to 400.
The badminton shaft is formed by laminating a fiber reinforced resin layer made of GPa reinforced fibers and a fiber reinforced resin layer made of reinforced fibers having a tensile elasticity of 60 GPa or less.

According to a second aspect of the present invention, the fiber reinforced resin layer made of a reinforcing fiber having a tensile modulus of elasticity of 60 GPa or less,
The badminton shaft according to claim 1, wherein the badminton shaft is arranged near a base end portion of the badminton shaft.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A badminton shaft according to the present invention comprises a fiber reinforced resin layer made of a reinforcing fiber having a tensile elastic modulus of 200 to 400 GPa, and a tensile elastic modulus of 60 GPa.
a) and a fiber-reinforced resin layer composed of the following reinforcing fibers. The badminton shaft is usually
It is composed of a bias layer and a straight layer. As the prepreg used for the bias layer and the straight layer, it is preferable to use a unidirectional prepreg because the orientation angle can be easily controlled.

The tensile modulus is 200 to 400 GP.
As the reinforcing fiber of a, alumina fiber, boron fiber, silicon carbide fiber, and carbon fiber can be used, but carbon fiber is most preferable because of its light weight. As the matrix resin, a thermosetting resin selected from an epoxy resin, an unsaturated polyester resin, a phenol resin, a silicone resin, a polyurethane resin and the like is used.

As the reinforcing fiber having a tensile modulus of elasticity of 60 GPa or less, a carbon fiber having a tensile strength of 1 to 3 GPa is desirable for improving the bending strength. Epoxy resins, unsaturated polyester resins,
A thermosetting resin selected from a phenol resin, a silicone resin, a polyurethane resin and the like is used.

The fiber reinforced resin layer made of reinforcing fibers having a tensile elastic modulus of 60 GPa or less has a low rigidity and an excellent tensile strength.
A badminton shaft having a fiber reinforced resin layer made of 00 GPa reinforcing fiber has a tensile elasticity of 60 GPa.
By adding a fiber reinforced resin layer made of reinforcing fibers of a or less, the bending strength can be improved without increasing the bending and torsional rigidity of the badminton shaft. Therefore, the durability of the racket frame can be improved. Moreover, the tensile elasticity is 200 to 400G.
A part of the fiber reinforced resin layer made of the reinforcing fiber of Pa is replaced with a fiber reinforced resin layer made of the reinforcing fiber having a tensile elasticity of 60 GPa or less, thereby reducing the bending and torsional strength. A badminton shaft with reduced bending and torsional stiffness can be formed without causing the bending.

In the present invention, the fiber-reinforced resin layer made of a reinforcing fiber having a tensile elastic modulus of 60 GPa or less,
In addition to providing a lightweight and durable shaft by providing it over the entire length of the badminton shaft as described above, by partially using it, for example, if it is used as a reinforcing layer at an arbitrary position, the bending and torsional rigidity of that portion is not much. The strength can be improved without changing. Further, when used as a constituent material layer at an arbitrary position, the bending and torsional rigidity can be reduced without lowering the bending and torsional strength of that portion.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is described below with reference to a tensile modulus of 60 GP.
An example will be described in which a fiber-reinforced resin layer made of the reinforcing fiber of a is partially used as a reinforcing layer in the vicinity of the shaft base end. 1 to 3 show the present embodiment. In FIG.
Is a racket frame on which the shaft 3 of this embodiment is mounted. As in the conventional case, a hitting portion 2 is connected to the tip of the shaft 3, and a grip 4 is attached to the end of the shaft 3.
Is attached.

As shown in FIG. 3, the shaft 3 is made of a prepreg obtained by impregnating a thermosetting synthetic resin into a reinforcing fiber having a tensile modulus of 200 to 400, for example. Prepreg sheets 71, 7 cut to ± 30 ° to ± 60 °
2, and a bias layer 7 formed by winding the mandrel 8 a plurality of times, and straight prepreg sheets 61 and 62 formed such that the orientation direction of the reinforcing fibers is 0 ° to ± 10 ° with respect to the shaft axis. , And a straight layer 6 wound therewith.

The wound state is as shown in FIG. In FIG. 2, an acrylic nitrile-based carbon fiber prepreg (tensile modulus of elasticity 230 GPa) manufactured by Toray Industries, Inc. was used as the straight layer 6 and the bias layer 7. The bias layer 7 is cut so that the orientation direction of the carbon fiber is in the directions of upper right 45 ° and upper left 45 ° with respect to the axis of the shaft. did. The prepreg 61 forming the straight layer 6 was cut so that the orientation direction of the carbon fibers was in the direction of the shaft axis, and was wound twice around a mandrel and laminated.

Then, a reinforcing layer 5 was formed by winding a reinforcing prepreg 51 formed by impregnating a thermosetting synthetic resin into a reinforcing fiber having a tensile elasticity of 60 GPa or less around the base end portion of the shaft. As the reinforcing prepreg 51,
Unidirectionally aligned prepregs are preferably used, and as the reinforcing fibers, those having a tensile elasticity of 60 GPa or less, more preferably 40 to 60 GPa and a tensile strength of about 1 to 3 GPa are used.

In this embodiment, a pitch-based carbon fiber prepreg (tensile modulus 54 GPa) manufactured by Nippon Graphite Fiber Co., Ltd. was used as the reinforcing prepreg 51 forming the reinforcing layer 5. The length of the reinforcing prepreg 51 of the reinforcing layer 5 is set in a range from 50 mm in the direction from the shaft base end 3b to the shaft tip 3a and from 10 mm in the direction from the shaft base end to the terminal direction of the shaft grip 3c. The kick point of the hand-held racket is preferably in a range from the base end of the shaft to a position of 50 mm from the front end side.

In molding, the reinforcing prepreg 5
1 is not disposed only on the distal end side with the shaft base end 3b as a starting point, but the shaft base end 3b extends from the shaft base end 3b toward the end of the shaft grip portion 3c.
, So that breakage due to stress concentration at the time of hitting the ball is prevented. Further, the orientation angle of the reinforcing fibers of the reinforcing prepreg 51 is 0 ° to ± 10
By arranging the reinforcing layers at an angle of about °, the arrangement of the reinforcing layer becomes more effective.

As shown in FIG. 3, the reinforcing prepreg 51
Is preferably formed in a substantially trapezoidal shape that is gradually widened from the distal end side 3a of the shaft to the proximal end side. In the present embodiment, the position where the reinforcing prepreg 51 is disposed is located at the outer peripheral portion of the straight layer 6 (FIG. 2A). In addition, between the bias layer 7 and the straight layer 6 (FIG. (B)) or the bias layer (FIG. 2)
(C)) can be arranged. The total length of the badminton shaft after curing and molding was 310 mm, the inner diameter at the narrow end was 3.9 mm, the outer diameter was 7 mm, the inner diameter at the large diameter end was 4.2 mm, and the outer diameter was 7.5 mm.

Table 1 shows the measurement results of the deflection amount of the product of the present invention and the comparative product. The measurement method uses a flex measurement standard machine of the Japan Golf Equipment Association, and according to the golf club shaft flex measurement method, the shaft is horizontal and 60 mm is fixed from the end of the shaft large diameter side,
A load of 3 kg was applied to a position 150 mm from the fixed point, and the amount of displacement due to the application of the load at that position was measured as the amount of deflection. The deflection amount of the product of this example was larger than that of the comparative product, and the hand portion was sufficiently bent.

As a comparative product, a shaft was formed in the same manner as in the example product except that the same prepreg having a straight layer and a bias layer as a reinforcing layer was used.

[0024]

[Table 1]

It should be noted that specific numerical values of the present invention are not limited to the numerical values of the above-described embodiment, and it is needless to say that the numerical values can be changed within a range in accordance with the gist of the present invention.

[0026]

According to the above construction, the racket equipped with the shaft of the present invention is a badminton shaft and a racket frame that is lightweight, does not significantly change the rigidity, and has sufficient strength as a badminton racket. Was.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a badminton racket according to an embodiment.

FIG. 2 is a cross-sectional view illustrating a laminated configuration of a shaft grip portion from a base end of the shaft of the embodiment.

FIG. 3 is an explanatory view of a prepreg cut shape and a stacking order of a shaft according to an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Badminton racket 2 Hitting part 3 Shaft 3a Shaft tip part 3b Shaft base end part 3c Shaft grip part 4 Grip 5 Reinforcement layer 51 Reinforced prepreg 6 Straight layer 61 Straight prepreg 62 Straight prepreg 7 Bias layer 71 Bias prepreg 72 Bias prepreg 8 Mandrel

Claims (2)

[Claims] 1. A tensile modulus of 200 to 400 GPa
A badminton shaft formed by laminating a fiber reinforced resin layer made of a reinforcing fiber of (1) and a fiber reinforced resin layer made of a reinforcing fiber having a tensile elastic modulus of 60 GPa or less. 2. The badminton shaft according to claim 1, wherein the fiber reinforced resin layer made of a reinforcing fiber having a tensile elasticity of 60 GPa or less is disposed near a base end portion of the badminton shaft.