JP4456379B2 - tennis racket - Google Patents

Description

  The present invention relates to a tennis racket, and more particularly to an apparatus that improves both flight performance and vibration damping.

In recent years, there has been a growing demand for rackets with high power and high flying performance, especially for women and seniors. Therefore, the material of the racket frame is not metal or wood, but is mainly fiber reinforced resin that is lightweight, has high specific strength, and has a high degree of design freedom. Usually, it has high strength and high elastic modulus like carbon fiber. It is molded from a thermosetting resin reinforced with fibers. However, the racket frame made of thermosetting resin tends to generate unpleasant vibration due to the impact at the time of hitting the ball due to the characteristics of the thermosetting resin, and the tennis elbow (so-called “tennis elbow”) generated by the impact transmitted to the elbow. It is a big cause.
On the other hand, a racket molded with a thermoplastic resin reinforced with fibers reflects the high toughness of the thermoplastic resin and has characteristics such as impact resistance and vibration damping properties. In comparison, the elastic modulus and strength are highly dependent on the environment, and there are disadvantages that characteristics such as rigidity are easily changed.

  In recent years, tennis rackets are also required to expand the sweet area in order to improve the spin, and to improve rebound and improve the ball flight performance. However, if the weight of the racket is added to increase the moment of inertia in order to improve the resilience, there is a problem that the operability is lowered.If the face area is increased and the gut movable range is increased, the weight increases. Invited, there is still a problem that the operability is lowered, and when the in-plane rigidity is increased by increasing the elasticity of the racket frame, there is a problem that the strength of the racket frame is lowered.

  In light of the above, a tennis racket that is lightweight, has high rigidity and high strength, has high vibration damping properties, and has high ball flying performance has been sought from the past, and has become a problem at the same time. .

  Among these demands, in particular, as a method for improving the vibration damping property without impairing the rigidity and strength of the racket frame, an improvement of a string protective material generally attached to the racket frame has been proposed. For example, in JP-A-8-107951 (Patent Document 1), in order to improve the absorbability of vibration transmitted from a string, as shown in FIG. It has been proposed to form a through hole I5 in the band portion I2 of the string protection material I composed of a band portion I2 connecting a plurality of cylinder portions I1. Moreover, in this Unexamined-Japanese-Patent No. 8-107951, as shown to FIG. 9 (B), the said belt | band | zone part I2 is made into a 2 layer upper and lower layer structure, and the lower layer I4 which has the said cylinder part I1 is formed with a softer material than the upper layer I3. Has also been proposed.

  Further, in Japanese Patent Application Laid-Open No. 2000-300698 (Patent Document 2), as shown in FIG. 10, a vibration absorbing member II2 in which a plurality of cylindrical portions II3 through which strings are inserted are connected by a belt portion II4, as shown in FIG. The vibration absorbing member II2 is divided into a band-shaped protective member II1 that covers the outside of the band portion II4, and the weight member II5 made of a high specific gravity material having a specific gravity of 1.5 or more and the vibration absorbing material II2 It has been proposed to increase vibration absorption, surface stability, and resilience by pressing the protective member II1 and attaching it to the racket frame R.

  Furthermore, Japanese Patent Application Laid-Open No. 2003-180883 (Patent Document 3) proposes a grommet assembly III including a first grommet member III1 having a low hardness and a second grommet member III5 having a high hardness as shown in FIG. . That is, the first grommet member III1 is formed by penetrating a string insertion hole III4 through a plurality of cylindrical portions III2 through which the string S is inserted and a band portion III3 connecting the cylindrical portions III2, and the second grommet member III5 is A string insertion hole III8 is formed through a plurality of peg parts III6 and a band part III7 connecting the peg parts III6, and the peg part III6 is inserted into the string insertion hole III4 of the first grommet member III1, A hard second grommet member III5 is attached to the outside of the grommet member III1, and by separating the second grommet member III5 from the racket frame R, the amount of impact and vibration of the racket is reduced, and a good hitting ball for the user It gives a sense and reduces the risk of premature damage to the string S.

  However, the string protective material I shown in Patent Document 1 absorbs the vibration of the string itself generated at the time of hitting the ball, and is not sufficient as a configuration for absorbing the vibration transmitted to the frame. There exists a problem that the intensity | strength of the string protective material I falls by formation. In addition, the string protective material II shown in Patent Document 2 is not configured to increase the deformation amount of the string protective material II itself, so that the resilience is not effectively improved and the ball flying performance cannot be improved. In addition, the attachment of the weight member II5 has a problem that it is difficult to reduce the weight and lower the operability.

  Furthermore, the arrangement position of the grommet assembly III shown in Patent Document 3 is limited. For example, when the head portion is viewed at 2 o'clock, 10 o'clock, 4 o'clock, and 8 o'clock when the head portion is viewed as a watch face, The small cylinder part III2 has a problem that it is easily damaged by the string inside the frame. Also, with this structure, the vibration of the string can be effectively reduced, but the vibration of the frame itself cannot be reduced.

JP-A-8-107951 JP 2000-300698 A JP 2003-180883 A

  The present invention has been made in view of the above problems, and it is an object to provide a tennis racket that is lightweight, has high rigidity and high strength, expands the sweet area, and achieves both high flight performance and high vibration damping. It is said.

In order to solve the above-mentioned problems, the present invention provides a string protective material having rigidity comprising a plurality of cylindrical portions through which a string is inserted and a band portion connecting the plurality of cylindrical portions, and an outer peripheral surface of a head portion of a racket frame. A tennis racket attached to at least a part of the side,
Between the band portion of the string protection material and the outer peripheral surface of the frame, a viscoelastic material is laminated on the frame side, and a cover material made of fiber reinforced resin (FRP) is laminated and interposed on the string protection material side ,
The viscoelastic material has a complex elastic modulus measured at a frequency of 10 Hz within a range of 2.0E + 7 dyn / cm ² or more and 1.0E + 10 dyn / cm ² or less at a temperature of 0 ° C. to 10 ° C. ,
The FRP cover material, said the complex elastic modulus measured at a frequency 10Hz is within 1.5E + 10dyn / cm ² or more 5.0E + 10dyn / cm ² or less at a temperature of 0 ° C. to 10 ° C. Provide tennis rackets to play.

  By interposing the viscoelastic material and the FRP cover material between the string protective material and the frame in this way, for example, even in a high-strength and high-elasticity racket frame, the viscoelastic material and the FRP cover material are string vibrations. The frame vibration can be effectively damped by suppressing the transmission to the frame. In particular, unlike the prior art, by interposing the FRP cover material between the viscoelastic material and the string protective material, the tension by the string can be received by the FRP cover material, so the load is evenly distributed and the unit area By making the perimeter load uniform and small, a higher vibration damping effect can be exhibited.

  In addition, by interposing the viscoelastic material between the string protective material and the frame, the string protective material can be deformed by utilizing the deformability of the viscoelastic material, so that a spring effect is obtained and the rebound of the hit ball is obtained. Can be increased. Further, by interposing a rigid FRP cover material between the string protective material and the viscoelastic material, the load due to the string is uniformly distributed, so that the spring effect due to the deformability of the viscoelastic material is effectively drawn out. The rebound of the hit ball can be effectively increased. Considering the above points and suppression of weight increase, the width of the viscoelastic material is preferably 10 mm or more and 30 mm or less, more preferably 15 mm or more and 25 mm or less, and particularly preferably 18 mm or more and 23 mm or less. Further, as the area of the FRP cover material is increased, the spring effect is also increased, and the resilience performance can be improved. The viscoelastic material is preferably a rubber, elastomer or resin having a low elastic modulus, and particularly a rubber alone or a rubber containing carbon black is preferred.

  Furthermore, since the viscoelastic material and the FRP cover material are light in weight and need only be attached to a fixed portion of the outer peripheral surface of the frame, they hardly affect the total weight of the racket and can sufficiently meet the weight reduction. . In particular, FRP is suitable for weight reduction because it can maintain strength even when the thickness is reduced compared to other resins (no fibers) having the same strength.

  Furthermore, in the above configuration, the viscoelastic material and the FRP cover material mainly exhibit a vibration absorbing function as a damper, and the string protective material itself is not configured to obtain a vibration damping effect. There is no need to use a soft material having a particularly low elastic modulus. As a result, it is possible to give a certain degree of rigidity to the cylindrical portion in contact with the string and the string protective material itself having the cylindrical portion, and the durability of the string protective material is improved, and the string to the string protective material is improved. Can also be prevented. In particular, when the top position of the frame head is 12 o'clock when the head of the frame is viewed at 2 o'clock, the 2 o'clock, 10 o'clock, 4 o'clock, and 8 o'clock positions have an acute angle with the cylindrical portion of the string protection material This is a portion where stress on the racket is easily concentrated, but the string protective material has rigidity so that this stress concentration can be prevented and the strength and durability of the racket can be increased.

  The string protective material preferably has a Shore D hardness of 50 to 80, particularly 55 to 75, in order to ensure the durability. Specifically, it is preferable to mold with a thermoplastic resin such as polyamide resin such as 11 nylon, 12 nylon, polyether block amide, etc., so that a certain degree of rigidity can be provided while having vibration absorption.

  The rigidity of the FRP cover material is preferably such that it does not greatly deform due to the tension of the string, and specifically, it is preferably molded from a composite of carbon fiber and epoxy resin. As the reinforcing fiber used in addition to the carbon fiber, a fiber generally used as a high-performance reinforcing fiber can be used. For example, graphite fiber, aramid fiber, silicon carbide fiber, alumina fiber, boron fiber, glass fiber, aromatic polyamide fiber, aromatic polyester fiber, ultrahigh molecular weight polyethylene fiber, and the like can be given. Metal fibers may also be used. These reinforcing fibers may be either long fibers or short fibers, and two or more of these fibers may be mixed and used. The shape and arrangement of the reinforcing fibers are not limited. For example, any shape and arrangement such as a single direction, a random direction, a sheet shape, a mat shape, a woven fabric (cross) shape, and a braided shape can be used. The elastic modulus of the FRP cover material is made different by changing the type of the reinforcing fiber.

  Examples of the resin used in addition to the epoxy resin include a thermosetting resin and a thermoplastic resin. Specifically, examples of the thermosetting resin include an epoxy resin, an unsaturated polyester resin, and a phenol resin. , Melamine resin, urea resin, diallyl phthalate resin, polyurethane resin, polyimide resin, silicon resin, and the like. Further, as the thermoplastic resin, polyamide resin, saturated polyester resin, polycarbonate resin, ABS resin, polyvinyl chloride resin, polyacetal resin, polystyrene resin, polyethylene resin, polyvinyl acetate resin, AS resin, A methacryl resin, a polypropylene resin, a fluororesin, etc. are mentioned.

  The viscoelastic material and the FRP cover material are provided with holes through which the cylindrical portion of the string protection material is inserted. Accordingly, the viscoelastic material can be attached to the outer peripheral surface of the frame over a certain length, and the viscoelastic material can be reliably fixed between the string protection material and the frame.

The viscoelastic material is within 2.0E + 7dyn / cm ² or more 1.0E + 10dyn / cm ² or less in the range of a temperature of complex elastic modulus measured at a frequency 10Hz is 0 ° C. to 10 ° C.. Within the above range, if it is less than 2.0E + 7 dyn / cm ² , stress concentration on the racket frame occurs and the racket frame is easily damaged, and the viscoelastic material is greatly deformed by the tension of the string. This is because the spring effect cannot be obtained and the resilience is not improved. On the other hand, if it exceeds 1.0E + 10 dyn / cm ² , the deformation amount of the string due to the load at the time of hitting the ball becomes small, a sufficient spring effect cannot be obtained, and the resilience performance is not improved. This is because the vibration damping property of the racket frame decreases.

Incidentally, the complex elastic modulus of the viscoelastic material, preferably, 3.0E + 7dyn / cm ² or more 5.0E + 9dyn / cm ² or less, in particular, 5.1E + 7dyn / cm ² or more 2.7E + 9 dyn / Cm ² or less is preferable.

The FRP cover material is within 1.5E + 10dyn / cm ² or more 5.0E + 10dyn / cm ² or less in the range of measured complex elastic modulus at a temperature of 0 ° C. to 10 ° C. at a frequency of 10 Hz. Within the above range, if less than 1.5E + 10 dyn / cm ² , the FRP cover material is also deformed by the tension of the string, a sufficient spring effect cannot be obtained, and the resilience is not improved. This is because the vibration damping property of the frame cannot be improved because it does not resonate. On the other hand, if it is greater than 5.0E + 10 dyn / cm ² , the vibration frequency does not match as a vibration absorber, and it is difficult to effectively attenuate the frame vibration.

The complex elastic modulus of the FRP cover material is preferably 2.0E + 10 dyn / cm ² or more and 5.0E + 10 dyn / cm ² or less, particularly 2.7E + 10 dyn / cm ² or more and 4.0E + 10 dyn. / Cm ² or less is preferable.

  The viscoelastic material has a thickness in the range of 1 mm to 5 mm. This is because if the thickness is less than 1 mm, the resilience and vibration absorbability of the racket frame cannot be sufficiently improved, and if it is thicker than 5 mm, the weight is increased and the operability is lowered.

  The FRP cover material has a thickness in the range of 0.5 mm to 2 mm. This is because if the thickness is less than 0.5 mm, the resilience and vibration absorbability of the racket frame cannot be sufficiently improved, and if it is thicker than 2 mm, the weight is increased and the operability is lowered.

When the hitting surface of the racket frame is regarded as a clock face and the top position is 12:00, the range from 1 o'clock to 2 o'clock and 10 o'clock to 11 o'clock, or / and the range from 4 o'clock to 5 o'clock and 7 o'clock. The viscoelastic material and the FRP cover material are attached between the frame and the string protective material at a position corresponding to the range of -8 o'clock.
The position corresponding to the range is a portion where the effective length of both the vertical string and the horizontal string is shortened, and the sweet area can be effectively expanded by arranging the viscoelastic material and the FRP cover material at the portion. Can do. In addition, when a viscoelastic material and an FRP cover material are disposed at the above-described part, weight is added to the outside of the center axis in the center direction passing through the axis of the grip portion, and the moment of inertia in the center direction increases. The racket is difficult to rotate around the central axis, and the surface stability is improved.

  In addition, for example, “attaching in the range from 1 o'clock to 2 o'clock” means that the attachment should be made so as to overlap at least a part of this range, and preferably at an intermediate position between the 1 o'clock position and the 2 o'clock position. It is good to attach so that it may overlap. On the other hand, since the sweet area is not enlarged and vibration absorption is not improved if it is mounted out of the range, the amount of protrusion is within the range of 0.25 hours for each of the start side and the end side, that is, the head portion. It is preferable to be within a range of 7.5 ° with the midpoint of the maximum length as the center.

  As described above, according to the present invention, the FRP cover material is interposed between the viscoelastic material and the string protective material, so that the load per unit area by the string is uniform and small. The damping effect is effectively extracted, and it is possible to more effectively realize the absorption of the string vibration generated at the time of hitting the ball and the suppression of the frame vibration. In addition, by interposing a rigid FRP cover material between the string protective material and the viscoelastic material, the elasticity of the viscoelastic material is more effectively drawn out, so the spring effect using the deformability of the viscoelastic material It is possible to effectively increase the resilience of the ball.

  In addition, the string protector that is in direct contact with the string due to the interposition of the viscoelastic material and the FRP cover material has the necessary rigidity to withstand the load during hitting without affecting the vibration damping of the frame. Can be increased. Therefore, although it is a high-strength and high-rigidity racket frame, it can have vibration damping properties and high flight performance.

  Furthermore, the viscoelastic material and the FRP cover are located at the positions corresponding to the 1 o'clock to 2 o'clock range and the 10 o'clock to 11 o'clock range, and / or the 4 o'clock to 5 o'clock range and the 7 o'clock to 8 o'clock range. By attaching the material, it is possible to effectively expand the sweet area while suppressing an increase in the weight of the frame.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all of the embodiments described below, the present invention is applied to a hard tennis racket frame.

  1 to 4 show a first embodiment of the present invention. As shown in FIG. 2, the tennis racket 10 has a string protective member 21 attached to the outer peripheral surface side of the racket frame 11, and the string protective member. The string S is stretched between the 21 and the racket frame 11 by interposing the viscoelastic material 31 (31a, 31b, 31c, 31d) and the FRP cover material (41a, 41b, 41c, 41d) at four locations. .

  The racket frame 11 includes a head portion 12, a throat portion 13, a shaft portion 14, and a grip portion 15 that are continuously formed. Both ends of a yoke 17 are connected to the throat portions 13 on both sides, and the ball striking surface F together with the head portion 12. Is formed. As shown in FIGS. 2 and 3, the head portion 12 is formed with a groove portion 18 that continuously attaches the viscoelastic material 31, the FRP cover material 41, and the string protection material 21 on the outer periphery thereof. In addition, as shown in FIG. 4, a plurality of gut holes 19 through which the string S is inserted are provided perpendicular to the frame direction, that is, through the width direction of the frame 11.

  As shown in FIG. 2, the string protecting member 21 is connected to a plurality of cylindrical portions 22 that pass through the insertion holes 24 through which the string S is inserted, and to project the plurality of cylindrical portions 22 toward the inner peripheral side. It is made of 11 nylon and is integrally molded. The belt portion 23 has a semicircular cross-section with a curved inner peripheral surface, and a maximum thickness of 2 mm.

The viscoelastic material 31 (31a to 31d) has a wide band shape with a thickness of 3 mm, a groove portion 32 is formed at the center, and the inner peripheral surface side is along the outer peripheral surface of the head portion 12 of the racket frame 11. It has a shape. The groove 32 is provided with a plurality of through holes 33 through which the tubular portion 22 of the string protection material 21 is inserted. This viscoelastic material 31 was molded from rubber having a lower elastic modulus than that of the string protective material 21. Specifically, the viscoelastic material 31 was vulcanized and molded by blending 100 parts by weight of styrene-butadiene rubber and 1.5 parts by weight of sulfur. Molded with rubber and made so that the complex elastic modulus measured at a frequency of 10 Hz is within a range of 2.0E + 07 dyn / cm ² or more and 1.0E + 10 dyn / cm ² or less at any temperature of 0 ° C. to 10 ° C. Yes.

The FRP cover material 41 (41a to 41d) has a wide band shape with a thickness of 1 mm, a groove portion 42 for attaching the band portion 23 of the string protection material 21 is provided at the center, and the inner peripheral surface side is provided. The viscoelastic material 31 has a shape along the outer peripheral surface. The groove portion 42 has a plurality of through holes 43 through which the cylindrical portion 22 of the string protection material 21 is inserted. This FRP cover material 41 is molded from a composite material of carbon fiber and epoxy, and the complex elastic modulus measured at a frequency of 10 Hz is 1.5E + 10 dyn / cm ² or more and 5.0E + 10 dyn / at any temperature of 0 ° C. to 10 ° C. It is created to be within a range of cm ² or less.

  As shown in FIGS. 3A and 3B, the viscoelastic material 31 (31a to 31d) and the FRP cover material 41 (41a to 41d) have a width substantially equal to the width of the racket frame 11 in the thickness direction. It corresponds. Further, as shown in FIG. 1, when the top position is set to 12 o'clock when the striking surface F of the racket frame 11 is regarded as a clock face, the position corresponds to a range from 1 o'clock to 2 o'clock (hereinafter referred to as “range A”). The viscoelastic material 31b and the FRP cover material 41b are located at a position where the viscoelastic material 31a and the FRP cover material 41a are in a range from 10:00 to 11:00 (hereinafter referred to as “range B”). The viscoelastic material 31c and the FRP cover material 41c are in a position corresponding to “range C”), and the viscoelastic material 31d and the FRP cover material 41d are in a position corresponding to a range from 7 o'clock to 8 o'clock (hereinafter referred to as “range D”). , The length is set to be arranged respectively. Here, for example, “range from 1 o'clock to 2 o'clock” indicates a range in which the start end is set to 1 o'clock and the end is set to 2 o'clock.

  When attaching the viscoelastic material 31 (31a to 31d), the FRP cover material 41, and the string protection material 21 to the gut stretch portion G of the racket frame 11, first, the tube portion 22 of the string protection material 21 Among them, the cylindrical portion 22 at each position corresponding to the range A to range D of the racket frame 11 is communicated with the through hole 43 of the FRP cover materials 41a to 41d and the through hole 33 of the viscoelastic materials 31a to 31d, respectively. As shown in FIG. 3A, the viscoelastic materials 31a to 31d and the FRP cover materials 41a to 41d are attached to the inner peripheral side of the string protective material 21 at a predetermined position.

  Next, by inserting the entire cylindrical portion 22 of the string protection material 21 to which the viscoelastic materials 31a to 31d and the FRP cover materials 41a to 41d are attached, through the gut holes 19 of the racket frame 11, a state shown in FIG. In the same manner, the viscoelastic materials 31a to 31d and the FRP cover materials 41a to 41d are laminated between the frame 11 and the string protection material 21 in the order of the viscoelastic materials 31a to 31d and the FRP cover materials 41a to 41d from the frame 11 side. Finally, the string S is stretched vertically and horizontally.

In the tennis racket 10 configured as described above, the viscoelastic material 31 interposed between the frame 11 and the string protective material 21 is made of rubber having a lower elastic modulus than the string protective material 21, and the viscoelastic material 31 and the string By interposing a rigid FRP cover material 41 between the protective material 21 and the FRP cover material 41, the load due to the string S at the time of hitting the ball is uniform and small, so that the elasticity of the viscoelastic material 31 is utilized. Both the vibration absorption effect and the spring effect utilizing the deformability of the viscoelastic material 31 are effectively extracted, and high vibration damping and high resilience can be obtained effectively. Further, by arranging the arrangement positions of the viscoelastic material 31 and the FRP cover material 41 so as to correspond to the ranges A, B, C, and D where the effective length of the string S is shortened both vertically and horizontally, the weight of the racket 10 is reduced. The sweet area can be effectively expanded while maintaining the property, and the surface moment can be improved by increasing the moment of inertia in the center direction.
Furthermore, the string protective material 21 that is in direct contact with the string S is made of 11 nylon, and can have a necessary rigidity while having a certain degree of vibration damping properties. Durability can be increased.

  FIG. 5 shows a second embodiment of the present invention. In this embodiment, the arrangement positions of the viscoelastic material 31 (31a, 31b) and the FRP cover material 41 (41a, 41b) are the range A and the range of the racket frame 11. There are two locations that hit B.

  FIG. 6 shows a third embodiment of the present invention. In this embodiment, the arrangement positions of the viscoelastic material 31 (31c, 31d) and the FRP cover material 41 (41c, 41d) are the range C and the range of the racket frame 11. It is assumed that there are two positions corresponding to D.

In any of the above-described embodiments, the viscoelastic material 31 is formed of a vulcanized rubber containing 100 parts by weight of styrene-butadiene rubber, 40 parts by weight of carbon black, and 1.5 parts by weight of sulfur, and has a frequency of 10 Hz. The measured complex elastic modulus is set to be in a range of 2.0E + 7 dyn / cm ² or more and 1.0E + 10 dyn / cm ² or less at any temperature of 0 ° C. to 10 ° C.
Also, FRP cover member 41 is molded from blended materials of carbon fiber and epoxy, complex elastic modulus measured at a frequency 10Hz is 1.5E + 10dyn / cm ² or more even under any temperature of 0 ° C. to 10 ° C. 5 0.0E + 10 dyn / cm ² or less.
Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

  As described above, the viscoelastic materials 31a and 31b (31c and 31d) and the FRP cover material 41 (41a and 41b) are disposed only in two places of the gut stretch portion G, and the viscoelastic materials 31a and 31b ( Even when 31c, 31d) is molded from carbon black rubber, the FRP cover materials 41a, 41b (41c, 41d) are effective for the vibration absorption effect and spring effect of the viscoelastic materials 31a, 31b (31c, 31d). It is possible to realize high vibration damping performance and resilience performance. In addition, the sweet area can be enlarged even if only two places are arranged. Conversely, by reducing the number of places to two, the racket weight can be reduced and the operability can be further improved. .

  As shown in Table 1 below, Examples 1 to 17 and Comparative Examples in which the mounting positions of the viscoelastic material and the FRP cover material, the material of the viscoelastic material, the complex elastic modulus, the thickness, and the complex elastic modulus of the FRP cover material were made different. 1 and 2 were prepared, and the coefficient of restitution, high repulsion area (sweet area) and vibration damping rate of the tennis racket were measured, and an actual hit test was also conducted.

The complex elastic modulus in Tables 1 and 2 is a temperature of 5 ° among numerical values measured under the following conditions using DVE-V4 manufactured by Rheology for both viscoelastic material and FRP cover material. The complex elastic modulus of the viscoelastic material is 2.0E + 7 dyn / cm at any temperature of 0 ° C. to 10 ° C. for Examples 1 to 6 and 9 to 17. It was in the range of ² or more and 1.0E + 10 dyn / cm ² or less. Complex elastic modulus of the FRP cover material, for example 1～9,11,12 includes a 0 ° C. to 10 in any of 1.5E + 10 dyn / cm ² or more 5.0E + 10 dyn / cm ² or less in the range even at a temperature of ° C. It was.
Sample: 5 mm wide x 30 mm long
Length of the deformed part in the sample: 20 mm (5 mm between both ends of 30 mm in length)
Initial strain: 10% (2mm)
Amplitude: 12 μm
Frequency: 10Hz
Mode: Tensile mode (viscoelastic material) Bending mode (FRP cover material)

Each of the racket frames 11 of Examples 1 to 17 and Comparative Examples 1 and 2 has a hollow shape molded with a fiber-reinforced thermosetting resin, has a cross-sectional shape with a thickness of 24 mm and a width of 12 mm, and an area of the hitting surface F is 110 square. The same shape in inches was used, and the frame weight and frame balance were set as shown in Table 1.
Specifically, the racquet frame is a mandrel (CF prepreg (Toray T300, 700, 800, M46J)) coated with an internal pressure tube made of 66 nylon. (14.5) was laminated to form a vertical laminate. The prepreg angles were 0 °, 22 °, 30 °, and 90 °, and they were laminated. The mandrel was pulled out and the laminate was set in a mold. The mold is clamped, and the mold is heated to 150 ° C. and heated for 30 minutes. At the same time, an air pressure of 9 kgf / cm ² is applied to the internal pressure tube, and the pressure is maintained, and by heat and pressure molding Created.
Also, in all of Examples 1 to 17 and Comparative Examples 1 and 2, the string protective material 21 used was formed of 11 nylon.

Example 1
The viscoelastic material 31 and the FRP cover material 41 have the same material, thickness, complex elastic modulus, and arrangement position as in the first embodiment. That is, the viscoelastic material 31 is molded from a vulcanized rubber blended with 100 parts by weight of styrene-butadiene rubber (SBR) and 1.5 parts by weight of sulfur, and has a thickness of 3 mm. The complex elastic modulus thus obtained was 5.07E + 07 dyn / cm 2. The FRP cover material 41 contains bisphenol A epoxy “Epicoat 828” manufactured by Japan Epoxy Resin, dicyandiamide curing agent “DICY50” manufactured by Japan Epoxy Resin, and DCMU curing agent “Dylonsol” manufactured by Hodogaya Chemical Industry. Molded from a composite material of the epoxy resin and a carbon fiber having a tensile modulus of 240 [Gpa] (“TR40” manufactured by Mitsubishi Rayon), the thickness is 1 mm, and the complex modulus measured under the above conditions is 2. 74E + 10 dyn / cm ² . The viscoelastic material 31 and the FRP cover material 41 are arranged one at each of the four positions A to D, and the weight of the racket 10 is 254 g.

(Example 2)
The viscoelastic material 31 was molded from a vulcanized rubber blended with 100 parts by weight of styrene-butadiene rubber (SBR), 1.5 parts by weight of sulfur and 40 parts by weight of carbon black, and measured under the above conditions. The complex elastic modulus was 3.86E + 08 dyn / cm ² , but the other configuration was the same as in Example 1.

(Example 3)
The viscoelastic material 31 and the FRP cover material 41 are all the same in material, thickness, complex elastic modulus, and arrangement position as in the second embodiment. That is, the arrangement positions of the viscoelastic material 31 and the FRP cover material 41 are one each at two places of the range A and the range B, the weight of the racket 10 is 251 g, and the other configurations are the same as those of the second embodiment. did.

Example 4
The viscoelastic material 31 and the FRP cover material 41 have the same material, thickness, complex elastic modulus, and arrangement position as in the third embodiment. That is, the arrangement position of the viscoelastic material 31 and the FRP cover material 41 is set to one each at two places of the range C and the range D, the weight of the racket 10 is set to 251 g, and the other points are the same as in the second embodiment. did.

(Example 5)
Although the thickness of the viscoelastic material 31 was 1 mm and the weight of the racket 10 was 249 g, the other configurations were the same as those in Example 2.

(Example 6)
The viscoelastic material 31 was molded with polyamide elastomer (“PEBAX5533” manufactured by ATOCHEM), and the complex elastic modulus measured under the above conditions was set to 2.72E + 09 dyn / cm ^2. 1 and the same configuration.

(Example 7)
The viscoelastic material 31 was formed of silicon rubber, and the complex elastic modulus measured under the above conditions was 1.41E + 07 dyn / cm ² , but the other configuration was the same as that of Example 1.

(Example 8)
The viscoelastic material 31 was molded from 11 nylon, and the complex elastic modulus measured under the above conditions was 1.45E + 10 dyn / cm ² , but the other configuration was the same as in Example 1.

Example 9
Although the thickness of the viscoelastic material 31 was 6 mm and the weight of the racket 10 was 260 g, the other configurations were the same as those in Example 2.

(Example 10)
The FRP cover material 41 uses glass fiber (ER ** 858R manufactured by Asahi Fiber Glass Co., Ltd.) having a tensile elastic modulus of 70 GPa as a reinforcing fiber, and has a complex elastic modulus measured under the above conditions of 1.00E + 10 dyn / cm. ² and the weight of the racket 10 was set to 255 g, but the other configuration was the same as that of Example 2.

(Example 11)
The FRP cover material 41 uses an aramid fiber (KEVLAR49 (registered trademark) manufactured by Toray Industries, Inc.) having a tensile elastic modulus of 112 GPa as a reinforcing fiber, and has a complex elastic modulus measured under the above conditions of 2.00E + 10 dyn / cm ^2. The weight of the racket 10 was 254 g, but the other configuration was the same as that of Example 2.

(Example 12)
The FRP cover material 41 uses a carbon fiber (HR40 manufactured by Mitsubishi Rayon Co., Ltd.) having a tensile elastic modulus of 390 GPa as a reinforcing fiber, and a complex elastic modulus measured under the above conditions is 4.50E + 10 dyn / cm ^2. The weight of 10 was 254 g, but the other configuration was the same as that of Example 2.

(Example 13)
The FRP cover material 41 uses a carbon fiber (SR40 manufactured by Mitsubishi Rayon Co., Ltd.) having a tensile elastic modulus of 490 GPa as a reinforcing fiber, a complex elastic modulus measured under the above conditions is 5.50E + 10 dyn / cm ² , and a racket Although the weight of 10 was set to 255 g, it was set as the same structure as Example 2 in the other point.

(Example 14)
The arrangement positions of the viscoelastic material and the FRP cover material were arranged at 3 to 4 o'clock and 8 to 9 o'clock. The other points were the same as in Example 2.

(Example 15)
The arrangement positions of the viscoelastic material and the FRP cover material were arranged at 0 to 1 o'clock and 11 to 12 o'clock (0 o'clock). The other points were the same as in Example 2.

(Example 16)
The thickness of the FRP cover material was 0.4 mm. The end point has the same configuration as that of Example 2.

(Example 17)
The thickness of the FRP cover material was 2.5 mm. The end point has the same configuration as that of Example 2.

(Comparative Example 1)
A tennis racket in which the viscoelastic material 31 and the FRP cover material 41 are not interposed at any position between the racket frame 11 and the string protection material 21 was used. The weight of the racket 10 was 248 g.

(Comparative Example 2)
Although only the viscoelastic material 31 was interposed between the viscoelastic material 31 and the string protective material 21 and the FRP cover material 41 was not interposed, the other configurations were the same as those of the ninth embodiment. The weight of the racket 10 was 250 g.

(Maximum coefficient of restitution, measurement of high repulsion area)
As shown in FIG. 7, the coefficient of restitution is such that the tennis racket 10 of the example and the comparative example is stretched with a tension of 60 pounds in length and 55 pounds in width, and each tennis racket 10 is free in a vertical state. The grip portion 15 was softly fixed to the ball, and a tennis ball was made to collide with the ball striking surface from the ball launcher at a constant velocity V1 (30 m / sec), and the velocity V2 of the bounced ball was measured. The restitution coefficient is the ratio (V2 / V1) between the firing speed V1 and the rebound speed V2, and the larger the restitution coefficient, the better the ball flies. By such a method, the maximum repulsion coefficient and the high repulsion region having a restitution coefficient of 0.38 or more were measured.

(Measurement of out-of-plane primary vibration damping rate)
As shown in FIG. 8 (A), the upper end of the head portion 12 is lifted by a string 51 as shown in FIG. 8A, and an acceleration pickup meter 53 is placed at one continuous point between the head portion 12 and the throat portion 13. It was fixed perpendicular to the ball striking surface. In this state, as shown in FIG. 8B, the other continuous point of the head portion 12 and the throat portion 13 was vibrated with an impact hammer 55. An input vibration (F) measured by a force pickup meter attached to the impact hammer 55 and a response vibration (α) measured by an acceleration pick-up meter 53 are subjected to a frequency analysis device 57 (manufactured by Hewlett-Packard Company, dynamics) through amplifiers 56A and 56B. Single analyzer HP3562A) was input and analyzed. The transfer function in the frequency domain obtained by the analysis was obtained, and the frequency of the tennis racket was obtained. The vibration damping ratio (ζ) was obtained from the following equation, and used as the out-of-plane primary vibration damping rate. Table 1 shows the average values measured for the racket frames of the examples and the comparative examples.

ζ = (1/2) × (Δω / ωn)
To = Tn × √2

(Measurement of out-of-plane secondary vibration attenuation rate)
As shown in FIG. 8C, the upper end of the head portion 12 is suspended by a string 51, and the acceleration pickup meter 53 is fixed perpendicularly to the ball striking surface at a continuous point between the throat portion 13 and the shaft portion. In this state, the frame 11 on the back side of the acceleration pickup meter 53 was vibrated with an impact hammer 55. Then, the attenuation rate was calculated by a method equivalent to the out-of-plane primary vibration attenuation rate, and the out-of-plane secondary vibration attenuation rate was obtained. Table 1 shows the average values measured for the racket frames of the examples and the comparative examples.

(Actual hit evaluation)
We conducted a questionnaire survey on the racket sweet area, flight, vibration, and operability. Table 1 shows the average value of the scoring results of 50 general players (evaluated that the more points, the better the flying, the wider the sweet area, the less the vibration, and the better the operability).

As can be confirmed from Table 1, Examples 1 to 17 in which the viscoelastic material and the FRP cover material are attached are compared with Comparative Example 1 in which neither the viscoelastic material nor the FRP cover material is attached. Evaluation that it was excellent in any point of operability was obtained.
Moreover, compared with Examples 1-17 and Comparative Example 2 in which only the viscoelastic material was attached and the FRP cover material was not attached, except for Examples 7, 8, 9, 14, 15, 17 and 17 Excellent performance, vibration damping and operability.
Example 7 was superior to Comparative Example 2 in terms of vibration damping and operability.
Example 8 was superior to Comparative Example 2 in terms of sweet area expansion, flight performance, and operability. Example 9 was superior to Comparative Example 2 in terms of sweet area expansion, flight performance, and vibration damping.
Examples 14, 15, and 17 were superior to Comparative Example 2 in terms of the sweet area expansion, flying performance, and vibration damping properties, except for operability.

When Examples 1, 2, 5, 6, 9 and Example 7 are compared, the complex elastic modulus of the viscoelastic material under the above conditions is in the range of 2.0E + 7 dyn / cm ² or more and 1.0E + 10 dyn / cm ² or less. In comparison with Examples 1, 2, 5, 6, and 9 in Example 7, Example 7 having a small complex elastic modulus had a low coefficient of restitution, and was evaluated as low in sweet area and flying performance. This is because the viscoelastic material is greatly deformed by the tension of the string and the spring effect cannot be obtained.
Moreover, when Examples 1, 2, 5, 6, 9 and Example 8 are compared, Example 8 whose complex elastic modulus is larger than the above range has low vibration damping in addition to sweet area and flying performance. It became evaluation. This is because the deformation of the string due to the load at the time of hitting ball becomes small, the sufficient spring effect cannot be obtained, the rebound becomes bad, and the vibration absorber becomes too high in frequency and the attenuation of the frame vibration is reduced. Due to.

When Examples 2, 11, and 12 are compared with Example 10, the FRP cover material has a complex elastic modulus under the above-described conditions in the range of 1.5E + 10 dyn / cm ² or more and 5.0E + 10 dyn / cm ² or less. As compared with Examples 2, 11, and 12, Example 10, which has a smaller complex elastic modulus, had a low coefficient of restitution, and was rated low in sweet area, flying performance, and vibration damping. This is because the FRP cover material is also deformed by the tension of the string, so that a sufficient spring effect cannot be obtained and the vibration does not resonate as a vibration absorber, so that the vibration damping property of the frame is lowered. Further, when Examples 2, 11, and 12 were compared with Example 13, Example 13 in which the complex elastic modulus of the FRP cover material was larger than the above range was evaluated as having low vibration damping. This is due to the fact that the frequency of the vibration absorber does not match and the attenuation of the frame vibration is reduced.

  When Example 2 is compared with Example 6 and Example 9, compared with Examples 2 and 6 in which the thickness of the viscoelastic material is in the range of 1 mm or more and 5 mm or less, Example 9 having a large thickness has poor operability. It became the result. This is due to the increased weight of the racket in Example 9.

In Example 14, since the arrangement positions of the viscoelastic material and the FRP cover material were 3 to 4 o'clock and 8 to 9 o'clock, they were not arranged in a portion where the string effective length was short, so Examples 1, 2, 9 etc. Compared with the case where it arrange | positions at 1 to 2 o'clock, 10 to 11 o'clock, etc., there was little expansion of the sweet area.
On the contrary, in Example 15, the arrangement positions of the viscoelastic material and the FRP cover material were arranged at 0-1 o'clock, 11-12 o'clock and the head top position, so that the operability was slightly lowered as compared with Examples 1 and 2 etc. .
In Example 16, since the thickness of the FRP cover material was reduced to 0.4 mm, the spring effect could not be exhibited, and the resilience and vibration absorbability could not be sufficiently improved.
In Example 17, since the thickness of the FRP cover material was increased to 2.5 mm, the vibration frequency of the racket frame was not met, the damper effect was lowered, and the vibration absorbability could not be sufficiently improved.

  The present invention relates to a tennis racket, but can also be applied to a racket frame for hitting balls such as badminton and squash.

1 is a front view of a tennis racket according to a first embodiment of the present invention. It is a disassembled perspective view which shows the principal part of the tennis racket shown in FIG. (A) (B) is sectional drawing which shows the attachment procedure of the string protective material, the viscoelastic material, and FRP cover material to the flame | frame of the tennis racket shown in FIG. It is a front view which shows the gut stretch part of the tennis racket shown in FIG. It is a front view which shows the head part of the tennis racket which concerns on 2nd embodiment of this invention. It is a front view which shows the head part of the tennis racket which concerns on 3rd embodiment of this invention. It is the schematic which shows the measuring method of the coefficient of restitution of a tennis racket. (A), (B), and (C) are schematic views showing a method of measuring the vibration attenuation rate of the racket frame. It is a figure of a prior art example. It is a figure of another prior art example. It is a figure of another prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Tennis racket 11 Racket frame 12 Head part 18 Groove part 21 String protective material 22 Cylinder part 23 Band part 31 Viscoelastic material 41 FRP cover material F Hitting surface G Gut stretch part S String

Claims (4)

This is a tennis racket in which a string protection material having rigidity consisting of a plurality of cylindrical portions through which strings are inserted and a band portion connecting the plurality of cylindrical portions is attached to at least a part of the outer peripheral surface side of the head portion of the racket frame. And
Between the band portion of the string protection material and the outer peripheral surface of the frame, a viscoelastic material is laminated on the frame side, and a cover material made of fiber reinforced resin (FRP) is laminated and interposed on the string protection material side ,
The viscoelastic material has a complex elastic modulus measured at a frequency of 10 Hz within a range of 2.0E + 7 dyn / cm ² or more and 1.0E + 10 dyn / cm ² or less at a temperature of 0 ° C. to 10 ° C. ,
The FRP cover material, said the complex elastic modulus measured at a frequency 10Hz is within 1.5E + 10dyn / cm ² or more 5.0E + 10dyn / cm ² or less at a temperature of 0 ° C. to 10 ° C. Tennis racket to play. The FRP cover material is provided with a groove portion for attaching the band portion of the string protection material at the center in the width direction, and the inner surface side is attached to the outer surface side of the viscoelastic material, and the FRP cover material is interposed between the FRP cover material and the frame. the viscoelastic material is sandwiched in the said viscoelastic material and FRP cover material has bored a hole for inserting the tubular portion of the string protection member, and in,
2. The viscoelastic material according to claim 1, wherein the viscoelastic material has a thickness in the range of 1 mm to 5 mm, the width is in the range of 10 mm to 30 mm, and the FRP cover material has a thickness in the range of 0.5 mm to 2 mm . tennis racket. The viscoelastic material is made of styrene butadiene rubber, styrene butadiene rubber compounded with carbon black, and made of one selected from polyamide elastomer, silicon rubber, and 11 nylon,
The FRP cover material is composed of an epoxy resin as a matrix resin, a carbon fiber, an aramid fiber or a glass fiber as a reinforcing fiber,
Tennis racket according to claim 1 or claim 2 wherein the string protection member consists of 50 to 80. polyamide resin in Shore D hardness. When the hitting surface of the racket frame is regarded as a clock face and the top position is 12:00, the range from 1 o'clock to 2 o'clock and 10 o'clock to 11 o'clock, or / and the range from 4 o'clock to 5 o'clock and 7 o'clock. The tennis racket according to any one of claims 1 to 3 , wherein the viscoelastic material and the FRP cover material are attached between the frame at a position corresponding to a range of -8 o'clock and the string protection material. .

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