JP2000350797A - Racket frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a racket frame excellent in damping vibrations. SOLUTION: This racket frame has a head part 3 forming the outline of the ball hitting surface, two throat parts 5 extending from the head part 3 to join with each other at one end, a shaft part 7 formed continuously from the joint part of the throat parts 5, and a handle part 9 formed continuously from the shaft part 7. The racket frame is made of a molding with a fiber- reinforced resin layer. And vibration absorbers made of a viscous elastic material with the tan δ at 10 C being 1.0 or larger are included in the head part 3, the throat parts 5 or the handle part 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racket frame used in ball games such as hard tennis and soft tennis, and more particularly to a racket frame formed of a molded article having a fiber reinforced resin layer.

[0002]

2. Description of the Related Art Bamboo, light metal and the like have been used for hard tennis rackets in the old days, but in recent years, fiber reinforced resin has been mainly used. Since the fiber reinforced resin has a high specific strength, the tennis racket can be reduced in weight while maintaining the strength. Tennis rackets made of fiber reinforced resin are also suitable for mass production.

[0003] When a player hits a ball with a tennis racket, the tennis racket vibrates. This vibration is transmitted to the player's body through the grip and gives the player discomfort. The vibration is also considered to be a cause of so-called tennis elbow. In particular, when the ball is hit in a portion other than the sweet area of the ball striking face, severe vibration is generated, and the player is seriously damaged.

[0004] The tennis racket made of the above-mentioned fiber reinforced resin has a higher vibration damping property than a metal tennis racket or the like. However, even the tennis racket made of the fiber reinforced resin does not have a sufficient vibration damping property. The problems of tennis elbow etc. have not been completely solved. Moreover, in recent years, the weight of the tennis racket made of fiber reinforced resin has been further reduced by increasing the strength and elasticity of the fiber. However, the tendency that the vibration damping property is reduced with the reduction in the weight is seen. . Further improvement in vibration damping properties is also desired for tennis rackets made of fiber reinforced resin.

Japanese Patent Application Laid-Open No. 10-337812 discloses a tennis racket in which an ionomer resin film is interposed in a fiber-reinforced resin laminate having an epoxy resin as a matrix. Since the ionomer resin is more excellent in vibration damping property than the epoxy resin, the vibration damping property of the tennis racket is improved by the interposition of the ionomer resin film.

[0006]

However, even with a tennis racket in which an ionomer resin film is interposed, the vibration damping property is not yet sufficient. Further, since the ionomer resin has poor adhesion to the epoxy resin, the ionomer resin film may be peeled off by repeated impact. When peeling occurs, the strength of the tennis racket will decrease. In fact, there is a demand for a tennis racket that has a further improved vibration damping property and is less likely to cause delamination.

The present invention has been made in view of such circumstances, and has as its object to provide a racket frame having excellent vibration damping properties.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a racket frame comprising a molded article provided with a fiber-reinforced resin layer, wherein the molded article has a tan δ at 10 ° C. of 1.0 or more. A racket frame characterized by having a vibration absorber made of a viscoelastic material interposed therebetween.

In this racket frame, 1
Since a vibration absorber made of a viscoelastic material having a tan δ of 1.0 or more at 0 ° C. is interposed, the vibration damping property is enhanced by the action of the vibration absorber. Therefore, the vibration transmitted to the human body is suppressed, the player is less likely to feel uncomfortable, and the occurrence of tennis elbow is also suppressed. t
If an δ is less than 1.0, the vibration damping effect of the vibration absorber may not be sufficiently exhibited. From this perspective,
tan δ is preferably 1.2 or more, and more preferably 1.5 or more. The larger the tan δ is, the higher the vibration damping property is. Therefore, the upper limit of the tan δ does not need to be particularly defined in the present invention. However, tan δ is 4.0 or less from the viewpoint of obtaining a material that can be used for the racket frame. Especially 3.
0 or less, more preferably 2.0 or less.

The tan δ of the vibration absorber is measured by a viscoelasticity measuring device (a viscoelastic spectrometer “DVA2” manufactured by Shimadzu Corporation).
00 improved version "). The measurement conditions were as follows: the frequency was 10 Hz, the jig was tensile, and the heating rate was 2
° C / min, the initial strain is 2 mm, and the displacement amplitude is ± 12.5 μm. The dimensions of the test piece (dumbbell) were 4.0 mm in width and 1.66 in thickness.
mm, and the length is 30.0 mm. Since the test specimen is chucked at both ends of 5 mm each, the length of the displaced portion of the test specimen is 20.0 mm.

[0011] The volume of the vibration absorber is preferably 0.05 cm ³ or more 20 cm ³ or less, 0.1 cm ³ or more 15cm
^It is preferably ³ or less. If the volume is less than the above range, the vibration damping property of the racket frame may not be sufficiently enhanced. Conversely, if the volume exceeds the above range, it is necessary to interpose a vibration absorber in the molded body. It can be difficult.

When the molded article of the racket frame of the present invention is formed by laminating a plurality of fiber reinforced resin layers, it is preferable that the vibration absorber is interposed between the fiber reinforced resin layers. Thereby, detachment of the vibration absorber is prevented. Of course, for example, even when the vibration absorber is attached to the inner wall surface of the hollow molded body, the vibration damping property of the tennis racket is improved. In addition, in a tennis racket in which a molded body is formed by injection molding, even when the vibration absorber is embedded in the synthetic resin meat or stuck on the inner wall surface of the hollow molded body, the vibration damping property of the tennis racket is reduced. Improves.

The shape of the vibration absorber is not particularly limited, and various shapes such as a sheet shape and a block shape can be adopted. When the vibration absorber is interposed between the layers of the fiber reinforced resin layer, the shape of the vibration absorber is preferably sheet-like from the viewpoint of facilitating manufacture.

In order to make the viscoelastic material have a tan δ at 10 ° C. of 1.0 or more, a polymer having a large tan δ itself may be used as a main polymer of the viscoelastic material. Examples of the polymer having a large tan δ itself include chlorinated polyethylene. Further, even if the polymer itself has not so large tan δ,
By adding a softener such as oil to this, tan
A viscoelastic material having δ of 1.0 or more can be obtained. Examples of such a viscoelastic material include, for example, polynorbornene in which a large amount of oil is blended. 10 ℃
Examples of the viscoelastic material having a tan δ of 1.0 or more include Elastage ED series (trade name) manufactured by Tosoh Corporation. Among these viscoelastic materials, it is preferable to select one having excellent adhesion to the matrix resin of the fiber reinforced resin layer. For example, a vibration absorber made of chlorinated polyethylene is preferable for the fiber reinforced resin layer in which the matrix resin is an epoxy resin. By selecting a viscoelastic material having excellent adhesion to the matrix resin, peeling of the vibration absorber is suppressed.

Usually, a racket frame has a head portion forming a contour of a hitting surface, two throat portions extending from the head portion and merging with each other at one end, and continuous from the junction of these throat portions to the throat portion. It has a formed shaft portion and a grip portion formed continuously with the shaft portion. Among them, when the vibration absorber is interposed in the head portion, the in-plane secondary attenuation rate (described in detail later) is mainly increased. Further, when a vibration absorber is interposed in the throat portion, the out-of-plane secondary damping rate (described in detail later) is mainly increased. Further, when the vibration absorber is interposed in the grip portion, the out-of-plane primary damping rate (described in detail later) is mainly increased.

[0016]

Embodiments of the present invention will be described below with reference to the drawings as appropriate. FIG. 1 is a front view showing a racket frame according to an embodiment of the present invention.
The racket frame includes a head portion 3, two throat portions 5, a shaft portion 7, and a grip portion 9. The head portion 3 has a striking surface contour, and its cross-sectional shape is substantially elliptical. One end of each of the two throat portions 5 extends from the head portion 3 and merges with each other at the other end. The shaft portion 7 extends from a place where the two throat portions 5 meet, and is formed continuously and integrally with the throat portion 5. The grip portion 9 includes the shaft portion 7
And continuously and integrally. The portion of the head portion 3 sandwiched between the two throat portions 5, 5 is a yoke portion 11. This racket frame is made of a molded article having a fiber reinforced resin layer in which the matrix resin is an epoxy resin and the reinforcing fibers are carbon fibers, and is hollow. A string is stretched over the racket frame, and a grip tape, an end cap, and the like are attached, thereby forming a racket for hard tennis.

FIG. 2 is an enlarged front view showing the head portion 3 of the racket frame of FIG. 1, and FIG. 3 is a III-III of FIG.
It is an expanded sectional view along a line. A vibration absorber 15 is interposed at the 1 o'clock position (the position indicated by the hour hand at 1 o'clock when the striking surface is viewed as a clock face) of the head portion 3 and the 11 o'clock position 13b. As is clear from FIG. 3, the vibration absorber 15 is interposed between the fiber reinforced resin layers.
The vibration absorber 15 has a sheet shape and is provided near the inside of the head portion 3. The vibration absorber 15 is made of chlorinated polyethylene and has a tan δ at 10 ° C. of 1.5. The vibration absorber 15 is provided on the inner wall surface 1 of the head 3.
7 may be attached. By interposing the vibration absorber 15 in the head portion 3 as described above, the in-plane secondary attenuation rate is mainly increased.

In order to interpose the vibration absorber 15 between the layers of the fiber reinforced resin layer, when winding a plurality of prepreg sheets around the mandrel, the vibration absorber 15 may be inserted between the prepreg sheets. In the case of a racket frame formed by reaction injection molding, the vibration absorber 15 is disposed in advance in the fiber pre-molded body, and the matrix resin is injected to form the vibration absorber 1 in the molded body.
5 can be interposed.

FIG. 4 is a front view showing a head portion 3 of a racket frame according to another embodiment of the present invention.
In this racket frame, the vibration absorber 15 is interposed in the yoke 11 of the head 3. Vibration absorber 15
Are interposed between the fiber-reinforced resin layers, similarly to the racket frame shown in FIG. By interposing the vibration absorber 15 in the head portion 3 as described above, the in-plane secondary attenuation rate is mainly increased.

In the racket frame shown in FIGS. 1 to 3, the vibration absorber 15 is interposed at the 1 o'clock position 13a and the 11 o'clock position 13b of the head portion 3, and the racket shown in FIG. In the frame, the vibration absorber 15 is interposed in the yoke 11 of the head 3, but the position of the vibration absorber 15 interposed in the head 3 is not limited thereto. For example, the vibration absorber 15 may be interposed at the top position. Further, the vibration absorber 15 may be provided at two positions, that is, the 4 o'clock position and the 8 o'clock position. In either case, the secondary in-plane attenuation rate of the racket frame is increased.

FIG. 5 is a front view showing a throat portion 5 of a racket frame according to still another embodiment of the present invention, and FIG. 6 is an enlarged sectional view taken along line VI-VI of FIG. The throat portion 5 has a vibration absorber 15 interposed. As is clear from FIG. 6, the vibration absorber 15 is interposed between the fiber reinforced resin layers over the entire circumference. The vibration absorber 15 may be attached to the inner wall surface 19 of the throat 5. By interposing the vibration absorber 15 in the throat portion 5 as described above, the out-of-plane secondary attenuation rate is mainly increased.

FIG. 7 is a front view showing a grip portion 9 of a racket frame according to still another embodiment of the present invention, and FIG. 8 is an enlarged sectional view taken along line VIII-VIII of FIG. A vibration absorber 15 is interposed in the grip portion 9. As is clear from FIG. 8, the vibration absorber 15 is interposed between the fiber reinforced resin layers of the vertical ribs 21 of the grip portion 9. By interposing the vibration absorber 15 in the grip portion 9 in this manner, the out-of-plane primary attenuation rate is mainly increased.

FIG. 9 is a front view showing a grip portion 9 of a racket frame according to still another embodiment of the present invention, and FIG. 10 is an enlarged sectional view taken along line XX of FIG. Two vibration absorbers 15 are interposed in the grip portion 9. As is clear from FIG. 10, the vibration absorber 15
The grip portion 9 is interposed between the fiber-reinforced resin layers along the side portions 23 on both sides. By interposing the vibration absorber 15 in the grip portion 9 in this manner, the out-of-plane primary attenuation rate is mainly increased.

[0024]

EXAMPLES Hereinafter, the effects of the present invention will be clarified based on examples, but it is needless to say that the present invention should not be construed as being limited based on the description of the examples.

Example 1 Five prepreg sheets in which the matrix was an epoxy resin and the reinforcing fibers were carbon fibers were wound around a mandrel. At this time, a length of 5 c
A sheet made of chlorinated polyethylene (tan δ at 10 ° C .: 1.5) having a width of 2.5 cm and a thickness of 0.2 mm was inserted. After removing the mandrel, the molded body was heated in a mold to obtain a racket frame of Example 1. The weight of this racket frame is 220g and the balance is 370
mm.

Comparative Example 1 In place of a chlorinated polyethylene sheet, an ionomer resin having the same dimensions and having a tan δ of 0.1 at 10 ° C. (trade name “Himilan 1652” manufactured by Du Pont-Mitsui Polychemicals) was used. A racket frame of Comparative Example 1 was obtained in the same manner as in Example 1 except that the sheet was used.

Example 2 A racket frame of Example 2 was obtained in the same manner as in Example 1 except that the number of chlorinated polyethylene sheets used was one and the insertion position was a yoke.

Example 3 Length 5 cm and thickness 0.2
A racket frame of Example 3 was obtained in the same manner as in Example 1 except that a chlorinated polyethylene sheet having a thickness of 2 mm was inserted over the entire circumference of the throat portion.

Comparative Example 2 An ionomer resin (trade name “Himilan 1652” of Mitsui DuPont Polychemicals Co., Ltd.) having the same dimensions and a tan δ of 0.1 at 10 ° C. was used instead of the chlorinated polyethylene sheet. A racket frame of Comparative Example 2 was obtained in the same manner as in Example 3 except that the sheet was used.

[Embodiment 4] The length is 5 cm and the width is 1.5 c.
Example 1 except that a chlorinated polyethylene sheet having a thickness of 2 mm and a thickness of 2 mm was used, and the insertion position was a vertical rib of the grip portion.
In the same manner as in the above, a racket frame of Example 4 was obtained.

[Embodiment 5] The length is 5 cm and the width is 1.5 c.
m, a racket frame of Example 5 was obtained in the same manner as in Example 1 except that two chlorinated polyethylene sheets each having a thickness of 2 mm were used, and the insertion position was set along positions on both sides of the grip portion. .

Comparative Example 3 Comparative Example 3 was performed in the same manner as in Example 1 except that the chlorinated polyethylene sheet was not inserted.
I got a racket frame.

[Measurement of Out-of-Plane Primary Attenuation Rate] Each racket frame is suspended by a string 25 as shown in FIG. 11 (a), and an acceleration pickup meter 27 is attached to the junction of the head 3 and the throat 5. Was. And the yoke part 11
Was shaken with an impact hammer (not shown). The damping rate was calculated from the input vibration measured by the force pickup meter attached to the impact hammer and the response vibration measured by the acceleration pickup meter 27, and was set as the out-of-plane primary damping rate. The results are shown in Table 1 below.

[Measurement of Out-of-Plane Secondary Attenuation Rate] Each racket frame was suspended by a string 25 as shown in FIG. 11B, and an acceleration pickup meter 27 was attached to the shaft portion 7. And the acceleration pickup meter 2 of the shaft portion 7
The point 31 on the back side of No. 7 was vibrated with an impact hammer (not shown). The damping rate was calculated from the input vibration measured by the force pickup meter attached to the impact hammer and the response vibration measured by the acceleration pickup meter 27, and was set as the out-of-plane secondary damping rate. This result is shown in Table 1 below.
Is shown in

[Measurement of In-Plane Secondary Attenuation Rate] Each racket frame is suspended by a string 25 as shown in FIG.
7 was attached. And the outside point 33 of the throat part 5
Was shaken with an impact hammer (not shown). The damping rate was calculated from the input vibration measured by the force pickup meter attached to the impact hammer and the response vibration measured by the acceleration pickup meter 27, and was set as the in-plane secondary damping rate. The results are shown in Table 1 below.

[Measurement of Lateral Rigidity] As shown in FIG. 12A, a racket frame was held on a fixed base 35 so that the hitting surface was vertical and the center axis of the shaft portion 7 was horizontal. . Then, a downward load (80 kgf) is applied to the head portion 3 from the side portion 37 of the head portion 3 by the pressing tool 39.
Was added. At this time, the load was divided by the amount of deformation of the side portion 37 in the vertical direction to obtain the lateral pressure rigidity. The results are shown in Table 1 below.

[Measurement of Flat Pressure Rigidity] As shown in FIG. 12B, each racket frame was held by a first fulcrum 43 near the top part 41 and a second fulcrum 47 near the grip end 45. A downward load (80 kg) is applied to the intermediate point between the first fulcrum 43 and the second fulcrum 47 by the pressing tool 49.
f) was added. At this time, the load was divided by the amount of deformation in the vertical direction at the intermediate point to obtain the flat pressure rigidity. The results are shown in Table 1 below.

[0038]

[Table 1]

In Table 1, the racket frame of each embodiment in which the sheet made of chlorinated polyethylene is interposed has better vibration damping properties than the racket frame of Comparative Example 3 in which the sheet is not interposed. The racket frames of Comparative Examples 1 and 2 in which an ionomer resin sheet is interposed also have an improved vibration damping property, but the extent is not as good as the racket frames of the respective examples. From these experimental results, the superiority of the racket frame of the present invention was confirmed.

Although the present invention has been described in detail by taking the racket frame for hard tennis as an example, the present invention can be applied to various racket frames such as a racket frame for soft tennis.

[0041]

As described above, since the racket frame of the present invention has excellent vibration damping properties, the player using the racket frame does not feel any discomfort due to vibration when hitting a ball, and the occurrence of tennis elbow is also reduced. Is suppressed.

[Brief description of the drawings]

FIG. 1 is a front view showing a racket frame according to an embodiment of the present invention.

FIG. 2 is an enlarged front view showing a head portion of the racket frame shown in FIG. 1;

FIG. 3 is an enlarged sectional view taken along line III-III of FIG.

FIG. 4 is a front view showing a head portion of a racket frame according to another embodiment of the present invention.

FIG. 5 is a front view showing a throat portion of a racket frame according to still another embodiment of the present invention.

FIG. 6 is an enlarged sectional view taken along line VI-VI of FIG.

FIG. 7 is a front view showing a grip portion of a racket frame according to still another embodiment of the present invention.

FIG. 8 is an enlarged sectional view taken along line VIII-VIII of FIG.

FIG. 9 is a front view showing a grip portion of a racket frame according to still another embodiment of the present invention.

FIG. 10 is an enlarged sectional view taken along line XX of FIG. 9;

11A is a front view showing a state of measurement of an out-of-plane primary attenuation rate, and FIG. 11B is a front view showing a state of measurement of an out-of-plane secondary attenuation rate. And FIG.
(C) is a perspective view showing a state of measurement of an in-plane secondary attenuation rate.

FIG. 12A is a front view showing a state of measurement of lateral pressure stiffness, and FIG. 12B is a front view showing a state of measurement of flat pressure stiffness.

[Explanation of symbols]

 3 Head 5 Throat 7 Shaft 9 Grip 11 Yoke

Claims (6)

[Claims] 1. A racket frame comprising a molded body provided with a fiber reinforced resin layer, wherein a vibration absorber made of a viscoelastic material having a tan δ at 10 ° C. of 1.0 or more is interposed in the molded body. Racket frame characterized by: 2. The racket frame according to claim 1, wherein the molded body is formed by laminating a plurality of fiber-reinforced resin layers, and the vibration absorber is interposed between the fiber-reinforced resin layers. . 3. The racket frame according to claim 1, wherein a matrix resin of the fiber reinforced resin layer is an epoxy resin, and a material of the vibration absorber is chlorinated polyethylene. 4. A head portion forming a contour of a striking surface, two throat portions extending from the head portion and merging with each other at one end, and formed continuously from the junction of the throat portions to the throat portion. The racket according to any one of claims 1 to 3, comprising a shaft portion and a grip portion formed continuously with the shaft portion, wherein the vibration absorber is interposed at least in the head portion. flame. 5. A head portion forming a contour of a striking surface, two throat portions extending from the head portion and joining each other at one end, and formed continuously from the junction of these throat portions to the throat portion. The racket according to any one of claims 1 to 3, comprising a shaft portion and a grip portion formed continuously with the shaft portion, wherein the vibration absorber is interposed at least in the throat portion. flame. 6. A head portion forming a contour of a striking surface, two throat portions extending from the head portion and joining each other at one end, and formed continuously from the junction of these throat portions to the throat portion. The racket according to any one of claims 1 to 3, comprising a shaft portion and a grip portion formed continuously with the shaft portion, wherein the vibration absorber is interposed at least in the grip portion. flame.