JP2003144585A - Tennis racket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve higher vibration damping performances by improving the yoke. SOLUTION: A throat part with which a head part and a shaft part of the body of a frame are built continuously is formed in a fork, the first and second yokes are arranged between both side frames of the throat part and the head part and the first yoke are made to continuously surround a gut application surface. At least one of the first and second yokes is made of material different from the body of the frame. Otherwise, at least one of the first and second yokes is joined onto to the body of the frame mechanically or through an adhesive to absorb vibrations of the body of the frame.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tennis racket and, more particularly, to improving a yoke by improving a yoke.

[0002]

2. Description of the Related Art In recent years, racket frames have been required to have properties such as light weight, high rigidity, high strength and durability, and fiber reinforced resin has become the main constituent material. Usually, the racket frame is molded from a thermosetting resin reinforced with fibers having high strength and high elastic modulus such as carbon fibers. The fiber-reinforced resin having the thermosetting resin as a matrix resin has high rigidity and is excellent, but there is a problem that the player is liable to become a tennis elbow when the shock is easily generated due to vibration.

Therefore, for example, in order to improve the vibration damping property of the racket frame of the fiber reinforced resin in which the epoxy resin is the matrix resin and the continuous fiber of the carbon fiber is the reinforced fiber, the organic material such as the aramid fiber or the ultra high molecular weight polyester fiber is used. Fiber may also be used. However, since the vibration damping rate is 0.6% or less and the vibration damping rate is not so high, and the rigidity and strength are small, there is a problem in rigidity when reinforced with only organic fibers.

Therefore, in recent years, there has been provided a racket frame made of a fiber-reinforced thermoplastic resin in which a thermoplastic resin having an excellent vibration damping property is used as a matrix resin and is reinforced with continuous fibers. Specifically, as a fiber reinforced resin comprising a thermoplastic resin matrix, a polyamide resin is used as a matrix resin, and continuous fibers or short fibers are used as reinforced fibers,
The manufacturing method is classified into the following three types. The vibration damping ratio of the racket frame made of this fiber reinforced thermoplastic resin is 0.9.
% Or more. (1) Injection molding of a polyamide resin containing short fibers. (Vibration damping rate 1.9%) (2) Fiber of matrix material and reinforcing fiber are laminated in the fibrous form, and internal pressure is applied at high temperature to melt and mold the matrix resin. (Vibration damping rate 0.92%) (3) Reinforcing fiber is placed in the mold in advance, and reaction injection molding (RIM) of polyamide resin monomer is performed. (Vibration damping rate 1.
1%) The racket frame made of the above fiber reinforced thermoplastic resin reflects the high toughness of thermoplastic resin, and has characteristics such as impact resistance and vibration damping that conventional thermoset resin rackets cannot achieve. Has been obtained.

However, in general, a thermoplastic resin has a large environmental dependency of elastic modulus and strength as compared with a thermosetting resin, and has a drawback that characteristics such as rigidity are easily changed depending on an environment in which the racket frame is used.

In order to solve the problems when the matrix resin is a thermoplastic resin and a thermosetting resin, a racket frame in which a thermoplastic resin and a thermosetting resin are combined is proposed. . For example, in Japanese Unexamined Patent Publication No. 6-63183, the portion extending from the throat portion to the grip portion is molded with a thermoplastic resin matrix, and the gut tension portion (face portion) surrounding the ball striking face is molded with a thermosetting resin matrix. . In addition, Japanese Patent Laid-Open No. 2000-704
In No. 15, RIM nylon is used partially,
A yoke made of carbon fiber / RIM nylon is formed in advance, then placed in a mold of the frame body, and integrally molded with a laminate of uncured carbon fiber / epoxy resin prepreg. Furthermore, JP-A-7-27540
As shown in FIG. 18, No. 1 is a tennis racket 1 in which a second yoke 4 is provided in the throat portion 2 substantially in parallel with the yoke 3 and a gut hole 5 is provided in the second yoke 4 together with the yoke 3. It is possible to stretch the gut 6 in both of the gut holes 5 of the third yoke 4 and the second yoke 4, and it is possible to make both the resilience performance and the spin performance compatible by selecting them.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the racket frame of No. 3183, since half of the frame body is formed of a thermoplastic resin matrix, it is not only easily affected by the usage environment, but also the vibration mode of the racket is not taken into consideration, and effective vibration damping effect is obtained. There was a problem that I could not get it. In addition, JP 2000-7
In the 0415 racket frame, the string tension (tension of the gut) and the load at the time of hitting hit the joint between the yoke and the frame body directly, so it is necessary to make the adhesion by integral molding very strong. However, there is a problem that cracks occur at the joints. Further, although shear stress is generated at the interface of the joint portion, it is difficult to suppress the frame vibration by the portion. In the racket frame 1 of Japanese Patent Laid-Open No. 7-275401, there is a problem in the vibration damping property, and the second yoke 4 has the gut 6
When the gut 6 is stretched, the gut 6 is fixed by the yoke 3 by passing the gut 6 through the yoke 3, so that the range of expansion and contraction of the gut is suppressed within the face surface, and there is a problem that the resilience performance is not sufficiently improved. .

In the racket frame, in addition to the demand for higher vibration damping, there is a demand from women and seniors for a tennis racket that can fly the ball far with a small amount of force. Increasingly weight reduction (reduction of moment of inertia) and high repulsion have been demanded. Furthermore, it has been found that the stability of the ball striking surface is required for athletes, and so-called in-plane rigidity is an important performance. In this way, the racket frame is
Light weight and good operability, high rigidity and high strength, high repulsion,
It is desired to have good vibration damping properties while having high surface stability. Also, some athletes prefer a strong shot feeling when hitting.

The present invention has been made in view of the above demands, and provides a racket frame which is lightweight, has a high repulsion, has a stable and high rigidity, and has a high vibration damping property, and a manufacturing method thereof. Is an issue. Another object is to make it possible to adjust the vibration damping property according to the preference of the shot feeling.

[0010]

In order to solve the above-mentioned problems, according to the present invention, a throat part which connects a head part and a shaft part of a frame body is formed into a bifurcated shape, and a first throat part is provided between both side frames of the throat part. A yoke and a second yoke are provided, and the first
The yoke and the head portion are connected to surround the ball striking face, and at least one of the first yoke and the second yoke is made of a material different from that of the frame body to absorb the vibration of the frame body, and A gut hole provided in both of the second yokes and stretched on the ball striking face may be stretched by passing through only the gut holes of the first yoke, or in the gut holes of both the first yoke and the second yoke. We provide a tennis racket that is characterized in that it is possible to choose whether to stretch it through.

With the above structure, since at least one of the first yoke and the second yoke and the frame body are made of different materials, the frame body is joined to the frame body at the joint portion between the frame body and the yoke made of a different material. The vibration damping property can be enhanced by concentrating the shearing force generated at the time of deformation. Further, when the frame main body is formed of a thermosetting fiber reinforced resin and the first yoke and / or the second yoke is formed of thermoplastic nylon, the vibration absorption of the yoke itself can be enhanced. Note that both the first yoke and the second yoke may be made different from the material of the frame body, and the material of the first yoke and the material of the second yoke may be made different.

Further, both or one of the first yoke and the second yoke is provided with a fitting hole extending in the length direction,
The vibration absorbing material having the gut holes arranged side by side in the fitting hole is fitted and fixed. In this case, the vibration absorbing material is fixed to the fitting hole via an adhesive, or is press-fitted and fixed by concave-convex fitting so as to be integrated with the fitting hole to form a part of the yoke. In any case, if the mounting member is made of a material having a good vibration damping property, such as a thermoplastic resin, the vibration damping property can be further improved, and vibrations can be prevented even at the bonding interface between the vibration absorbing material and the fitting hole. When the first yoke and the second yoke have the above-described configurations, the vibration damping property can be dramatically improved.

Further, when the first yoke and the second yoke are provided with the gut holes respectively as described above, when the gut stretched on the ball striking face is passed through only the gut hole of the first yoke, the gut is stretched. Has the same repulsion performance as before. On the other hand, the first
When the gut is stretched through the gut holes of both the yoke and the second yoke, the length of the gut stretched becomes large and the amount of deformation of the gut can be increased, so that the resilience performance can be improved and the controllability can be improved. Can also be increased. In this way, it becomes possible to adjust the strength of the resilience performance according to the player's preference.

Further, since the tennis racket has the first yoke and the second yoke, the rigidity in the in-plane direction is improved. Therefore, it is not usually necessary to add a high-elasticity reinforcing layer used to increase the rigidity, and the tennis racket can be reduced in weight even if the second yoke is attached.

The material of the yoke is made of fiber reinforced resin, resin alone, metal, wood, or a composite material thereof. From the viewpoint of high vibration damping effect, the fiber-reinforced thermoplastic resin is preferable.

The first and second yokes are manufactured by injection molding in a state of being reinforced with short fibers such as carbon fibers. Combed yarn of polyamide fiber and carbon fiber is woven into a braid (braid), A method of molding by heating and melting polyamide in reinforcing fiber, RIM made by coating nylon tube on foamed epoxy and further laminating carbon braid and injecting RIM nylon monomer
There are methods such as nylon molding.

On the other hand, when the yoke is made of fiber reinforced thermoplastic resin, the material of the frame body is made of resin reinforced with continuous fibers, and is different from the material of the yoke.
The frame body is preferably made of fiber reinforced thermosetting resin. The frame body may be formed of a fiber-reinforced thermoplastic resin, and at least one of the first yoke and the second yoke may be formed of a fiber-reinforced thermosetting resin.

Further, according to the present invention, the throat portion, which connects the head portion and the shaft portion of the frame main body, is formed into a bifurcated shape, and the first yoke and the second yoke are provided between both side frames of the throat portion. The first yoke and the head portion are continuous to surround the gut tension surface, and at least one of the first yoke and the second yoke is mechanically bonded to the frame body or bonded with an adhesive, and the bonded. The gut which is the vibration absorbing portion at the interface, has gut holes in both the first yoke and the second yoke, and is stretched on the gut tension surface is the first gutter.
(EN) A tennis racket having a configuration in which it is possible to select whether to stretch through only the gut holes of the yoke or to stretch through the gut holes of both the first and second yokes. .

In the above-mentioned tennis racket, at the joint between the frame body and at least one of the first yoke and the second yoke, the shearing force generated when the frame body is deformed is concentrated to enhance the vibration damping property. The joining of the frame main body and the yoke may be mechanical joining or joining via an adhesive, but it is more preferable that the area of the joining portion is large. This is because if the joint area is large, it is likely to receive a shearing force that contributes to vibration damping. Also in this tennis racket, as in the tennis racket of the present invention, when the gut stretched over the ball striking face is stretched only through the gut hole of the first yoke, the rebound performance becomes the same as the conventional one. When it is stretched through the gut holes of both the yoke and the second yoke, the resilience performance can be improved and the strength of the resilience performance can be adjusted. Further, the first yoke and the second
Since the yoke is provided, the rigidity in the in-plane direction is improved. Therefore, it is not necessary to add a high-elasticity reinforcing layer that is usually used to increase rigidity, and the weight of the tennis racket can be reduced.

The above-mentioned mechanical joining means is a means for joining without using a material having an adhesive property or a chemical bonding force, and is a means for joining due to a combination of differences or changes in the shapes or the like of the objects to be joined. is there. Specifically, concave-convex fitting, screwing, fitting, meshing, hooking and locking, bolts / nuts, springs and the like can be mentioned, and concave-convex fitting, screwing and the like are preferably used. This mechanical joining force naturally has a joining force capable of holding the string force and withstanding the impact force of the ball.

Specifically, a convex portion or a concave portion is provided on either one of the inner surface of the frame body and the joint surface of the yoke,
On the other hand, a concave portion or a convex portion that fits into the convex portion or the concave portion is provided, and these are joined by concave and convex fitting. At this time, if the frame main body is provided with the convex portion and the yoke is provided with the concave portion, the constraint of the yoke with respect to the frame main body is reduced, and the frame body can be easily fitted.

An adhesive or / and a vibration-damping film or a vibration-damping sheet having excellent vibration absorption may be interposed on the bonding surface formed by the mechanical bonding means. That is, regarding the connection between the frame main body and the yoke, in addition to mechanical connection, an adhesive having a smaller elastic modulus than the yoke and the frame main body may be used together, and in that case, the adhesive has an adhesive effect. . Even if the above-mentioned adhesive is interposed, since the elastic modulus is smaller than that of the frame body and the yoke, shear stress can be concentrated on that portion, and the vibration damping property of the entire frame can be adjusted by selecting the adhesive. It becomes possible to do. In addition, a high damping material (film, sheet, damping paint) is applied to at least a part of the joint surface between the frame body and the yoke.
May be interposed, and the damping performance can be easily adjusted by selecting this damping material. These damping materials may be used alone or in combination with an adhesive. By interposing the above-mentioned adhesive and damping material on the joint surface between the frame body and the yoke, it is possible to prevent an unpleasant sound from being generated. As the vibration damping film, a die porgy film manufactured by CCI is preferably used. As the above adhesive, one having high flexibility is preferable, in addition to the epoxy type,
There are adhesives such as urethane type.

Further, even when the frame body and the first yoke and / or the second yoke are joined by mechanical joining means or joined by an adhesive, the frame body and the yoke are joined in the same manner as the tennis racket described above. It is preferable to use different materials. This allows
This is because the vibration of the frame body can be further absorbed.

As a separate body from the first yoke and the second yoke, one of them is integrally molded with the frame main body and the other is mechanically joined or joined with an adhesive, or the first yoke and the second yoke. Each of the yokes is also mechanically bonded or bonded to the frame body by an adhesive. When one of the first yoke and the second yoke is made of a different material from the frame body, both the first yoke and the second yoke may be molded integrally with the frame body.

When the first yoke and the second yoke are integrally molded, the first yoke and the second yoke are integrally molded through the auxiliary frame portions arranged on the inner surfaces of both side frames of the throat portion, and the frame body is machined. It is preferable to physically bond or bond with an adhesive. With the above configuration, since the auxiliary frame portion is joined to the throat portion, the joining surface with the frame body is large, so that it is possible to improve vibration absorption and joint strength.

Further, the tip of the auxiliary frame portion is joined and attached to the tip of the shaft of the throat portion, a projection is provided from the joining portion, and the projection is fitted into a notch provided at the tip of the shaft portion. Is preferred. By providing the notch in the shaft portion, it is possible to increase the bonding strength of the auxiliary frame portion to the frame body.

The gut hole of the first yoke is preferably larger than the gut hole of the second yoke. When the gut holes are passed through the gut holes of the first yoke and the second yoke, if the gut holes of the first yoke are larger than the gut holes of the second yoke,
This is because the gut is not fixed by the gut hole of the first yoke, the length of the gut can be effectively used, and the resilience performance can be improved. The diameter of the gut hole of the first yoke is 2.0 mm to 6.0 mm, and preferably 2.2 mm to 5.5 mm. If the diameter of the gut hole is smaller than 2.0 mm, the gut will contact the gut hole,
This is because it does not contribute to the improvement of the resilience performance. On the other hand, 6.0
This is because if it is larger than mm, the strength of the first yoke becomes low.

It is preferable to provide a projection portion for positioning and holding the gut to be bridged between the adjacent gut holes on the surface of the first yoke and / or the second yoke opposite to the ball striking face side. Since the gut is positioned and held by the projection and the gut is protected, it is not necessary to attach a gut protective material after the gut is stretched as in the conventional case.

As the resin used for the yoke, as mentioned above, thermosetting resin, thermoplastic resin, metal, wood and the like can be mentioned. Specifically, as the thermosetting resin,
Examples thereof include epoxy resin, unsaturated polyester resin, phenol resin, melamine resin, urea resin, diallyl phthalate resin, polyurethane resin, polyimide resin, and silicon resin. 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, methacryl resin , Polypropylene resin, fluororesin and the like.

As the reinforcing fibers used in the fiber-reinforced resin, fibers generally used as high-performance reinforcing fibers can be used. Examples thereof include carbon fiber, graphite fiber, aramid fiber, silicon carbide fiber, alumina fiber, boron fiber, glass fiber, aromatic polyamide fiber, aromatic polyester fiber, and ultra-high molecular polyethylene fiber. Alternatively, metal fibers may be used. Carbon fiber is preferable because it is lightweight and has high strength. These reinforcing fibers may be either long fibers or short fibers, and two or more kinds of these fibers may be mixed and used. The shape and arrangement of the reinforcing fibers are not limited, and include, for example, single direction, random direction, sheet shape, mat shape, woven (cloth) shape,
Any shape and arrangement such as a braid can be used.

Examples of the metal include lightweight metals such as aluminum, titanium and magnesium, or an alloy containing each metal as a main component may be used. As the matrix resin, for example, a polyamide resin or an alloy of polyamide and ABS is preferably used.

The frame body is not limited to a laminate of fiber reinforced prepregs, but a reinforcing fiber is wound around the mandrel by filament winding to form a layup, which is placed in a mold. It is also possible to use a frame body formed by filling a thermoplastic resin such as rim nylon.

An adhesive for joining the frame body and the first yoke and / or the second yoke, and a fitting hole for the first yoke and / or the second yoke to which a vibration absorbing material is fitted, for the adhesive. Examples of the adhesive include those listed below.・ High peel strength impact resistant adhesive based on cyanoacrylate and elastomer. For example, manufactured by ThreeBond
1731 and 1733.・ By uniformly dispersing the rubber particles in the epoxy resin,
Room temperature curing type two-part epoxy resin with stable toughness.
As a high shear adhesive type, for example, 2082C manufactured by ThreeBond Co., Ltd.・ A one-component moisture-curing elastic adhesive that contains a special polymer containing silyl groups as its main component and that reacts with a small amount of moisture in the air to cure.
For example, 1530 manufactured by ThreeBond.・ Urethane adhesive "Espren" ・ Ciba Geigy company "Redux 609""AW10"
6 / HV953U "" AW136A / B "・ LOCTITE" E-214 "・ 3M" DP-460 "" 9323B /
A "

[0034]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show a tennis racket according to a first embodiment of the present invention, in which a head portion 10, a throat portion 11 and a shaft portion 12 which are gut tension portions are formed by a frame main body 100 made of a fiber reinforced resin pipe. The grip portion 13 is continuously formed, and the first yoke 14 is provided at the tip between the both side frames of the throat portion 11.
The second yoke 15 is provided at a substantially intermediate portion in the length direction of the.

As shown in FIG. 2, the first yoke 14 and the second yoke 15 are provided with gut holes 14a and 15a. Therefore, a case where the gut G between the gut hole 10a of the head portion 10 and the gut hole 14a of the first yoke 14 is stretched to form the head portion 10 and the first yoke 14 as a gut tension portion, It is possible to select a case where the gut hole 14a is passed through and the gut hole 15a of the second yoke 15 is stretched to form a gut stretched portion between the head portion 10 and the second yoke 15. The area can be changed.

The frame body 100 is made of thermosetting fiber reinforced resin, the first yoke 14 and the second yoke 15 are made of thermoplastic fiber reinforced resin, and the frame body 100 and the first and second yokes 15 and 15 are made of thermoplastic fiber reinforced resin. The yokes 14 and 15 are made of different materials and are integrally molded in the mold.

More specifically, as shown in FIG. 4, as the frame main body 100, a pipe-shaped layup 31a is prepared by laminating carbon fiber prepreg using carbon fibers as reinforcing fibers and epoxy resin as matrix resin. The first yoke 14 is made by laminating an epoxy prepreg on the surface of the foam material, and the second yoke 15 is made of 6 nylon and has a length of 1 m.
The layup filled with 30% of m carbon fiber is injection-molded with a molding die. The layup 31a of the frame body is filled in the cavity 32a of the molding die 32, and the layup 31b of the first and second yokes is also arranged in the cavity 32a. At this time, an epoxy adhesive and a silane coupling agent are applied to the joints between the layup 31a of the frame body and the first and second yokes 31b. Next, the mold is clamped and heated at 150 ° C. for 30 minutes, at the same time, an air pressure of 9 kgf / cm ² is applied to the inner pressure tube 30 of the layup 31a, and the inner pressure tube 30 is pulled out after the integral molding. ing.

A groove 14 is formed on the ball striking face side of the first yoke 14.
b, and the gut hole 14a is formed from the bottom surface of the groove 14b to the second position.
It is provided so as to penetrate to the yoke 15 side. The gut holes 15a of the second yoke 15 are formed on the same straight line as the gut holes 14a, and as shown in FIGS. 3B and 3C, protrusions 15b are provided on both sides in the thickness direction between the gut holes 15a. , Gut hole 1
The gut G to be bridged between the 5a is positioned and held. Note that the first yoke 14 may also be provided with a similar protrusion for positioning and holding the gut.

The gut hole 14a of the first yoke 14 has a large hole diameter so that the gut G can be loosely inserted to increase the degree of freedom of the gut G. It is preferable that the gut hole 14a of the first yoke 14 is larger than the gut hole 15a of the second yoke 15. If it is difficult to make the diameter different in processing the gut hole, the gut hole 15a of the second yoke 15 is also made large similarly to the gut hole 14a of the first yoke 14. Further, the gut hole 10 at the position of 4 to 5 o'clock (8 to 7 o'clock) of the head portion 10 which is continuous with the first yoke 14.
A-1 also has a large pore size. Therefore, these gut holes 10a-1 are long and have a large diameter.

In the tennis racket having the above structure, since the first yoke 14, the second yoke 15 and the frame body 100 are made of different materials, the shearing caused by the deformation of the frame body 100 at the time of hitting the joint surface between them. By concentrating the force, the vibration of the frame main body 100 can be absorbed, and the vibration transmitted to the player who holds the grip portion 13 of the frame main body 100 can be attenuated. Further, since the tennis racket includes the second yoke 15 in addition to the first yoke 14, the rigidity in the in-plane direction can be particularly improved. Therefore, it is not necessary to additionally provide a high-elasticity reinforcing layer used to increase the rigidity, and the tennis racket can be reduced in weight.

Further, as shown in FIGS. 1 and 5 (A), when the gut G is stretched through the gut holes 14a and 15a of both the first yoke 14 and the second yoke 15,
Since the gut hole 14a of the yoke 14 is enlarged and the gut G is loosely inserted, the effective utilization length of the gut G stretched between the second yoke 14 and the head portion can be increased. Also,
Since the gut holes 10a-1 in the head portion 10 at 4 to 5 o'clock (8 to 7 o'clock) are also long and have a large hole diameter, the effective utilization length of the gut G becomes large. In this way, by making the effective use length of the gut G large on the yoke side and the head portion close to the yoke, the sweet area of the ball striking face S can be expanded, and the resilience performance of the tennis racket can be enhanced. Furthermore, the gut is positioned and held by the projection 15b provided on the surface of the second yoke 15 opposite to the ball striking face, and the gut is protected, and the gut protective material is attached after the gut is stretched as in the conventional case. No need.

On the other hand, as shown in FIG. 5 (B), when the gut G is passed through only the gut hole 14a of the first yoke 14 and the gut is not passed through the gut hole 15a of the second yoke 15, the gut hole is formed. The grommet 33 is fitted to 14a, and the gut G is stretched through the hollow hole 33a of the grommet 33. When the gut G is stretched between the first yoke 14 and the head portion 10, the degree of freedom of the gut is higher than when the gut G is stretched between the second yoke 15 and the head portion 10. Although it becomes smaller and the resilience performance decreases, the controllability becomes good. In this way, the repulsion performance is different, and the player can select the repulsion performance and control performance suitable for himself / herself. The gut G stretched over the first yoke 14 can be protected by the second yoke 15.

In the first embodiment described above, both the first yoke 14 and the second yoke 15 are made of a material different from the material of the frame body 100, but either the first yoke 14 or the second yoke 15 is used. May be made of a material different from that of the frame body 100, and the other may be made of the same material as the frame body 100.

FIGS. 6 to 8 show a tennis racket according to a second embodiment of the present invention. The difference from the first embodiment is that the yoke body 20 in which the first yoke and the second yoke are integrally molded.
Is provided, and the yoke body 20 is mechanically joined to the frame body 100 ′.

In the yoke body 20, the first yoke 24, the second yoke 25, and the auxiliary frame portion 26 are integrally formed, and the first yoke 24 and the auxiliary frame portion 26 form a substantially triangular frame portion, and both sides are formed. The second yoke 25 is laid across the intermediate portion of the auxiliary frame portion 26. Both sides of the first yoke 24 are joined to the head portion 10 'of the frame body and the auxiliary frame portion 26 is joined to the throat portion 11'.

The head portion 1 is provided on both sides of the first yoke 24.
It extends to the 0 o'clock position at 5 o'clock (7 o'clock), and a concave portion 24c is provided in this portion so as to be fitted with the convex portion 10'a provided on the head portion 10 'and mechanically via a urethane adhesive. We are joining. The auxiliary frame portion 26 extends along the inner surfaces of the throat portions 11 ′ on both sides to a position reaching the shaft portion 12 ′,
Projecting pieces 27 are provided from the tips of the extended left and right auxiliary frame portions 26. The auxiliary frame portions 26 on both sides have a non-uniform width direction,
As shown in FIG. 8, a concave portion 11′a corresponding to the shape of the auxiliary frame portion 26 is provided on the inner surface of the throat portion 11 ′ and is fitted and locked. Further, the protruding piece 2 protruding from the tip of the auxiliary frame portion 26
7 is a slit 1 provided at the center of the tip of the shaft portion 12 '.
2'a is inserted and fitted.

The first yoke 24 and the second yoke 25 of the yoke body 20 have the gut holes 24 as in the first embodiment.
a and 25a are provided. Each of the gut holes 24a and 25a of the first and second yokes has a conical shape with a large hole diameter on the ball striking face side, and the gut hole 24a has a larger hole diameter than the gut hole 25a.

The processing for changing the hole diameters of the gut holes 24a and 25a as described above can be easily carried out because they are later attached to the frame main body 100 '. When the frame main body and the first and second yokes are integrally molded in the mold as in the first embodiment, when a vertical gut hole is drilled from the ball striking face side, Since the drill body hits the head portion, it is difficult to form a hole from the ball striking face side. Therefore, it is not easy to form the hole on the ball striking face side with a large hole diameter. The other shapes are similar to those of the first embodiment, and thus the description thereof will be omitted.

In the second embodiment, the frame body 100 'is made of the same material as in the first embodiment, while the yoke body 2
No. 0 is provided by injection molding the same material as the frame body. In addition, the yoke main body 20 is connected to the frame main body 100 '.
It may be formed of a different material.

In the above-described tennis racket of the second embodiment, since the frame body 100 'and the yoke body 20 are formed as separate members and then joined by the mechanical joining means and the adhesive, the racket is attached to the joining surface between them. The vibration damping performance of the racket frame can be improved by concentrating the shearing force generated when the frame is deformed.

Further, since the gut holes 24a, 25a of the first yoke 24 and the second yoke 25 are large on the ball striking face side, the degree of freedom of the gut G can be further increased and the resilience performance can be improved. it can. In addition, the positional deviation of the gut holes can be alleviated. The other functions and effects are the same as those in the first embodiment, and thus the description thereof will be omitted.

In the second embodiment described above, the first yoke and the second yoke are not provided with protrusions for holding and positioning the gut on the surface opposite to the ball striking face, but as shown in FIG. The protrusions 24b and 25b may be provided on the surfaces of the yoke 24 and the second yoke 25 opposite to the ball striking face side.

In the second embodiment, the yoke body 20 and the frame body 100 'are joined by the mechanical joining means and the adhesive, but a damping film may be sandwiched between the joining surfaces of the two. Thereby, the vibration damping property can be further improved. Further, in the second embodiment, the urethane-based adhesive is used, but in addition, an adhesive or the like having excellent vibration absorption may be used depending on the required performance.

FIG. 10 shows the third embodiment, in which the layup of the yoke body 20 'integrally formed by the first yoke 24' and the second yoke 25 'is formed through the auxiliary frame portion 26' along the throat portion. The yoke body 20 'is provided and the cavity 3 of the die 32 is laid up together with the frame body 100'.
2a may be filled and integrally molded. That is, in the second embodiment, the yoke main body is joined to the frame main body by mechanical means, but the yoke main body may be integrally formed with a mold as in the first embodiment.

11 and 12 show the fourth embodiment. In the fourth embodiment, both the first yoke 34 and the second yoke 35 are integrally formed with the frame main body 100 ″. The first yoke 34 and the second yoke 35 each have a large fitting hole 34a in the longitudinal direction. 35a is formed in advance, and vibration absorbing materials 38 and 39, in which the gut holes 36 and 37 are formed at required intervals, are fitted and fixed in the fitting holes 34a and 35a, respectively. It is integrated with the yoke 35.

The fitting holes 34a and 35a have their lower portions stepwise widened to provide recesses 34a1 and 35a1 on both left and right sides, while the vibration absorbers 38 and 39 project their lower portions stepwise to project to both left and right side portions. The parts 38a and 39a are provided. Mating hole 3
Vibration absorbing materials 38 and 39 are inserted into 4a and 35a and fixed by an adhesive material. In this state, the first yoke 34 and the second yoke 35 do not project to the vibration absorbers 38 and 39 and are integrated as a part of the first yoke and the second yoke.

The first yoke 34 and the second yoke 35 are made of a material in which epoxy prepreg is laminated on the surface of a foam material as in the first embodiment, and the vibration absorbers 38, 39 are formed of nylon of thermoplastic resin. ing.

The gut hole 36 of the vibration absorber 38, which is inserted and fixed in the fitting hole 34a of the first yoke 34, is formed in the second yoke 35.
Similar to the above-described embodiment, the vibration absorbing member 39 inserted into and fixed to the fitting hole 35a is smaller than the gut hole 37.

With the above structure, since the interface where the first yoke 34 and the vibration absorbing material 38 are joined and the interface where the second yoke 35 and the vibration absorbing material 39 are joined has a wide area due to the concave and convex fitting, the interface at this interface is large. The vibration damping property can be enhanced, and since the mounting members 38, 39 themselves are molded from nylon, which is a thermoplastic resin having a good vibration absorbing property, the vibration damping property can be further enhanced. Furthermore, the vibration absorber 3
It is also possible to arbitrarily adjust the material of Nos. 8 and 39, the size and position of the gut holes, etc., and it is possible to easily provide rackets having various performances. Other operations are similar to those of the first and second embodiments, such that the gut holes of the first yoke and the second yoke can be selected and the gut can be attached.
The description is omitted.

FIG. 13 shows a fifth embodiment, in which the first yoke 44 and the second yoke 45 are separately formed of the same material and different from the frame main body 100 ″. Extension portions 44 that fit with the frame body 100 ″ are provided on both sides of the first yoke 44 and the second yoke 45.
c and 45c are provided, and they are fitted into the recesses 100 "a and 100" b formed in the frame body 100 "and fixed by an adhesive. Other configurations and operational effects are the first and second embodiments. Since it is the same as, the description will be omitted.

Examples of the tennis racket of the present invention and comparative examples were prepared, and the rigidity of the side surface of the head portion and the hitting surface,
Vibration (out-of-plane direction primary damping rate, out-of-plane direction secondary damping rate, string damping rate) and restitution coefficient were measured, and further, actual hitting test was conducted.

The tennis rackets of the examples to and the comparative examples all have substantially the same shape, and the total length of the racket is 68.
It was set to 5 mm. The head portion of the frame had a substantially elliptical cross-sectional shape with a thickness of 28 mm in the out-of-plane direction and a width of 13 to 16 mm in the in-plane direction. The area of the ball striking surface was 114 square inches. Also, the material and manufacturing method of the frame body are all the same, a 66 nylon tube is covered on the φ14.5 mandrel, and CF prepreg (Toray T-300, T-700, T-800, M46J) is laminated on the tube. did. The fiber angles of the prepreg are 0 °, 22 °, 3
The layers were laminated at 0 ° and 90 °. After stacking, pull out from the mandrel to create a layup of the frame body, fill the cavity of the molding die, and clamp the die to 150
While heating at 30 ° C. for 30 minutes, an air pressure of 9 kgf / cm ² was applied to the internal pressure tube 30 and the tube was pulled out. As a result, a pipe-shaped racket frame having a hollow portion was obtained. After that, 15cm from the racket end
The rib inside the grip up to the position was cut.

The tennis racket of the example corresponds to the first embodiment, and the frame body, the first yoke, and the second yoke are separately manufactured and integrally molded with a mold. It should be noted that neither the first yoke nor the second yoke is provided with a protrusion for positioning and holding the gut. The first yoke is made by laminating epoxy prepreg on the surface of foam material, and the second yoke is made of 6
Nylon filled with 30% of carbon fiber having a length of 1 mm was molded using an injection molding die. An epoxy adhesive and a silane coupling agent were applied to the joints between the frame body and the first and second yokes for reinforcement. The diameter of the gut hole was 4.0 mm, which is the same as that of a normal gut hole, in both the first yoke and the second yoke.

The tennis racket of the example was produced in the same manner as the tennis racket of the example, and the gut hole diameter of the first yoke was 5.0 mm, which was larger than usual, and the gut hole diameter of the second yoke was 4.0 mm.

The tennis racket of the embodiment has the same shape as that of the embodiment, and the frame main body, the first yoke and the second yoke are separately manufactured and integrally molded with a mold. The first yoke was formed by using 6 Nylon filled with 30% of carbon fiber having a length of 1 mm by using a mold for injection molding. The second yoke was formed by laminating epoxy prepreg on the surface of the foam material. Further, when integrally molded in the mold, an epoxy adhesive and a silane coupling agent were applied to the joint portion of the frame main body and the first yoke and the second yoke for reinforcement. The gut hole diameter of the first yoke was 5.0 mm, and the hole diameter of the second yoke was 4.0 mm. Further, the gut hole in the portion corresponding to 4 to 5 o'clock (8 to 7 o'clock) of the head portion was set to φ7 mm.

The tennis racket of the embodiment has the same shape as that of the embodiment, and the frame body, the first yoke and the second yoke are separately manufactured and integrally molded with a mold. Both the first yoke and the second yoke were made of 6 nylon filled with 30% of carbon fiber having a length of 1 mm and injection-molded using a mold for injection molding. Further, at the time of integral molding, an epoxy adhesive and a silane coupling agent were applied to the joints between the frame body and the first and second yokes to reinforce them. The gut hole diameter of the first yoke was 5.0 mm, and the hole diameter of the second yoke was 4.0 mm. Also, at 5 o'clock (7
The gut hole in the portion corresponding to (when) was φ7 mm.

The tennis racket of the example corresponds to the fourth embodiment, in which the frame body, the first yoke and the second yoke are separately manufactured, and the frame body and the first yoke are integrally molded with a mold, The second yoke was fitted to the first yoke for mechanical joining, and further joined with urethane adhesives. Both the first and second yokes are made of 6 nylon filled with 30% of 1 mm long carbon fiber,
Injection molding was performed using a mold for injection molding. Also, the first
The diameter of the gut hole of the yoke was 5.0 mm, and the diameter of the gut hole of the second yoke was 4.0 mm. In addition, 5 of the head
The gut hole in the portion corresponding to the hour (7 o'clock) was φ7 mm.

The tennis racket of the example corresponds to the third embodiment, and is integrally formed through the auxiliary frame portion that extends the first yoke and the second yoke along the throat portion. The yoke was integrally molded with the frame body by a mold. When the cavity of the mold was filled, it was fitted with concavo-convex and fixed with an epoxy adhesive and a silane coupling agent. The first yoke and the second yoke were made of 6 nylon filled with 30% of carbon fiber having a length of 1 mm and injection molded using a mold for injection molding. The gut hole diameter of the first yoke was 5.0 mm, and the hole diameter of the second yoke was 4.0 mm. Further, the gut hole in the portion of the head portion corresponding to 5 o'clock (7 o'clock) was φ7 mm.

The tennis racket of the example corresponds to the second embodiment, and the yoke body is formed by interposing the first yoke and the second yoke with the auxiliary frame portion. The yoke main body was fitted into the frame main body in a concavo-convex manner to perform mechanical joining. For both the first yoke and the second yoke, 6 nylon filled with 30% of a carbon fiber having a length of 1 mm was used by using an injection molding die.
Injection molded. The gut hole diameter of the first yoke is 6.0 mm,
The hole diameter of the second yoke was 4.0 mm. Further, the gut hole in the portion of the head portion corresponding to 5 o'clock (7 o'clock) was φ7 mm. Further, a width of 5 mm and a depth of 5 on the ball striking face side of the first yoke.
A groove of mm was provided.

In the tennis racket of the embodiment, the first yoke and the second yoke are provided with protrusions so that the gut can be stretched without attaching the grommet. Other configurations were the same as those in the example.

The tennis racket of the comparative example is an ordinary tennis racket, in which the frame main body and the first yoke are integrally formed by a mold, and the second yoke is not provided. The first yoke is made by stacking epoxy prepreg on the surface of the foam material,
The gut hole diameter of the yoke was 4.0 mm. In the tennis racket of the comparative example, the frame body, the first yoke, and the second yoke were respectively provided with layups, and the tennis racket was integrally molded with a mold.
The first yoke and the second yoke were made of the same material in which epoxy prepreg was laminated on the surface of a foam material, and the gut hole diameter was 4.0 mm for both the first yoke and the second yoke.

Table 1 below shows the materials, shapes, presence / absence of grommets, weights, balance positions (dimensions from the grip end of the tennis racket to the center of gravity position), and test results of the examples and comparative examples. In Table 1, EP of the yoke material is the same as the material used for the frame body, and NY is a material in which 6% nylon is filled with 30% of carbon fiber having a length of 1 mm. At the time of measurement, only the gut is comparatively first
In the examples and the comparative examples, the gut was passed through the gut holes of the first yoke and the second yoke, and the gut was stretched. At that time, except for the example, a cylindrical grommet having a thickness of 1 mm was attached to the gut hole.

[0073]

[Table 1]

(Measurement of Lateral Pressure Rigidity) As shown in FIG. 14, the lateral pressure rigidity is measured by holding the tennis racket of the embodiment and the comparative example with the tennis racket in the horizontal direction and the hitting surface F in the vertical direction. In this state, a load of 784N was applied by the flat plate P to the side 10s of the upper head portion 10, the spring constant was calculated from the displacement at the time of load, and the lateral pressure rigidity was measured.

(Measurement of Rigid Surface Rigidity) For measuring the radial striking surface rigidity (rigidity in the out-of-plane direction), as shown in FIG.
The top 10t of No. 0 was supported by the jig 61 (R15), and was also supported by the jig 62 (R15) at a position 340 mm away from the top 10t and extending from both sides of the throat portion 11 to the first yoke 14. . In this state, at a position 170 mm away from the receiving jig 61 in the direction of the receiving jig 62, 78
A load of 4 N was applied, the spring constant was calculated from the displacement under load, and the ball striking surface rigidity was measured.

(Measurement of out-of-plane primary vibration damping rate) FIG.
As shown in (A), in the tennis rackets of each of the examples and comparative examples, the upper end of the head portion 10 is hung with a string 51, and an acceleration pickup meter 53 is provided at one continuous point between the head portion 10 and the throat portion 11. Fixed vertically to the frame surface. In this state, as shown in FIG. 16B, the impact hammer 55 vibrates the other continuous point of the head portion 10 and the throat portion 11. A frequency analysis device 57 (manufactured by Hewlett-Packard Co., dynamic) is provided for input vibration (F) measured by a force pickup meter attached to the impact hammer 55 and response vibration (α) measured by an acceleration pickup meter 53 via 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 formula, and made the out-of-plane primary vibration damping ratio. The measurement was performed on each tennis racket for each of the examples and comparative examples.

Ζ = (1/2) × (Δω / ωn) To = Tn / √2

(Measurement of out-of-plane secondary vibration damping ratio) FIG.
As shown in (C), in the tennis rackets of each of the examples and the comparative examples, the upper end of the head portion 10 is suspended by a string 51, and the acceleration pickup meter 53 is attached to the frame surface at the continuous point between the throat portion 11 and the shaft portion 12. Fixed vertically.
In this state, the frame on the back side of the acceleration pickup meter 53 was vibrated by the impact hammer 55. Then, the damping rate is calculated by the same method as the out-of-plane primary vibration damping rate, and the out-of-plane 2
The next vibration damping rate was used. The measurement was performed on each tennis racket for each of the examples and comparative examples.

(Measurement of damping rate of string vibration) FIG.
As shown in (D), in the tennis rackets of each of the examples and comparative examples, the head portion 1 with the strings stretched.
The upper end of 0 was suspended by a string 51, and an acceleration pickup meter 53 was fixed at a continuous point of the throat portion 11 and the shaft portion 12 perpendicularly to the frame surface. In this state, the string was vibrated by the impact hammer 55 in the central portion of the head portion 10. Then, the damping rate was calculated by a method equivalent to the out-of-plane primary vibration damping rate, and was set as the string vibration damping rate. The measurement is
Each tennis racket was measured for each example and comparative example.

(Measurement of Coefficient of Restitution) As shown in FIG. 17, the coefficient of restitution was measured by tensioning the tennis rackets of the examples and the comparative examples with a gut tension of 60 pounds in length and 55 pounds in width. The grip was softly fixed so as to be free in the vertical state, and a tennis ball was made to collide with the hitting surface from the ball launching machine at a constant speed V1 (30 m / sec), and the speed V2 of the bounced ball was measured. . The coefficient of restitution is the ratio of the firing speed V1 and the repulsion speed V2 (V2
/ V1), indicating that the higher the coefficient of restitution, the better the flight of the ball. The coefficient of restitution was measured by such a method.

(Method of Actual Hit Test) An actual hit test was conducted using the tennis rackets of the examples and comparative examples. The actual hit test is performed by 66 intermediate / advanced players (woman who has been playing tennis for 10 years or more, and who still plays at least 3 days a week), and has a maximum of 5 points for ball jumping, controllability, and operability ( The higher the score, the better the performance), and the average value was obtained.

As is clear from the results shown in Table 1 above,
In Examples and Comparative Examples in which the second yoke was provided, the side pressure and the striking surface were excellent in rigidity as compared with the Comparative Example in which the second yoke was not provided. Therefore, it was confirmed that the rigidity is improved by providing the second yoke. In addition, it was confirmed by an actual hit test that the controllability was improved by improving the rigidity.

The examples 1 to 6 in which the materials of the frame main body and the first yoke were different were excellent in the out-of-plane first-order attenuation rate as compared with the examples and the comparative examples in which the materials were the same. Similarly, in Examples 1 to 5 in which the materials of the frame main body and the second yoke are different from each other, the out-of-plane secondary attenuation rate was excellent as compared with Examples and Comparative Examples in which the materials were the same. This allows
It was confirmed that the vibration damping property is improved by changing the material of the first yoke and the second yoke from that of the frame body.

The examples 1 through 4 in which the first yoke and the second yoke are integrally formed are different from the examples in which the first yoke and the second yoke are separately formed, as compared with the examples in which the first yoke and the second yoke are separately formed. Both were excellent. As a result, it was confirmed that the vibration damping property was improved by integrally molding the first yoke and the second yoke. Further, the embodiment in which the first yoke and the second yoke are integrally molded and then mechanically joined to the frame body is more out-of-plane than the embodiment in which the first yoke, the second yoke and the frame body are all integrally molded. Both the primary attenuation rate and the out-of-plane secondary attenuation rate were excellent. As a result, it was confirmed that the vibration damping property is improved by mechanically joining the integrally molded first and second yokes to the frame body. Similar results were obtained from the vibration absorption of the actual hit test.

The examples in which the grommets were not attached to the first yoke and the second yoke were excellent in the string attenuation rate as compared with the examples to which the grommets were attached and the comparative examples. From this, it was confirmed that the string attenuation rate was improved by not mounting the grommet.

Example in which the gut is stretched by the second yoke
The comparative example had a higher coefficient of restitution than the comparative example in which the gut was stretched over the first yoke. As a result, it was confirmed that the resilience performance was improved by stretching the gut with the second yoke. Further, in Examples 1 to 3 in which the gut hole diameter of the first yoke was made larger than usual, the coefficient of restitution was higher than in the usual Examples and Comparative Examples. As a result, it was confirmed that the resilience performance was further improved by making the gut hole diameter of the first yoke larger than usual. Similar results were also obtained from the flight of the ball in the actual hit test.

[0087]

As is apparent from the above description, according to the tennis racket of the present invention, when at least one of the first yoke and the second yoke and the frame body are made of different materials, the vibration of the frame body is absorbed. Can be made. Further, when the gut stretched on the gut stretched surface is stretched through only the gut hole of the first yoke, the rebound performance becomes the same as the conventional one, and the guts of both the first yoke and the second yoke become. When stretched through the holes, the resilience performance can be improved. That is, the strength of the resilience performance can be adjusted according to the player.

Further, at least one of the first yoke and the second yoke is mechanically bonded to the frame body or bonded with an adhesive to absorb the vibration at the time of hitting the ball by the bonded interface. You can further,
Since the tennis racket of the present invention includes the first yoke and the second yoke, the rigidity in the in-plane direction is particularly improved. Therefore, it is not necessary to add a high-elasticity reinforcing layer that is usually used to increase rigidity, and the weight of the tennis racket can be reduced.

[Brief description of drawings]

FIG. 1 is a front view of a tennis racket according to a first embodiment of the present invention.

FIG. 2 is an enlarged perspective view of an essential part of the first embodiment.

3A is an enlarged perspective view of a main part of the tennis racket of the first embodiment, FIG. 3B is a drawing of the second yoke as seen from the side opposite to the ball striking face, and FIG. 3C is CC of FIG. It is a line sectional view.

FIG. 4 is a schematic perspective view showing a method for manufacturing a tennis racket.

FIG. 5A is a sectional view showing a state in which a gut is passed through the gut holes of the first yoke and the second yoke, and FIG. 5B is a sectional view showing a state in which the gut is passed through only the gut hole of the first yoke. .

FIG. 6 is a front view of the tennis racket of the second embodiment.

FIG. 7 is an enlarged view of a main part of the second embodiment.

FIG. 8 is an enlarged perspective view of a main part on the frame body side of the second embodiment.

FIG. 9 is a sectional view showing a modified example of the second embodiment.

FIG. 10 is a schematic perspective view showing a third embodiment.

FIG. 11 is a schematic exploded perspective view showing a fourth embodiment.

FIG. 12 is an enlarged front view of the essential parts of the fourth embodiment.

FIG. 13 is an enlarged front view of the essential parts of the fifth embodiment.

FIG. 14 is a schematic diagram showing a method for measuring lateral pressure rigidity.

FIG. 15 is a schematic diagram showing a method of measuring the striking surface rigidity.

16 (A) to 16 (D) are schematic diagrams showing a method for measuring a vibration damping ratio of a racket frame.

FIG. 17 is a schematic diagram showing a method of measuring the coefficient of restitution.

FIG. 18 (A) is a front view of a conventional tennis racket,
(B) is an enlarged view of a main part.

[Explanation of symbols]

10 head 11 Throat 12 Shaft 13 Grip part 14, 24, 34 44 1st yoke 15, 25, 35, 45 Second yoke 14a, 24a, gut holes 15a, 25a, gut hole 20 Yoke body 26 Auxiliary frame 34a, 35a Fitting hole 38,39 Vibration absorber S ball striking surface G Gut

Continued front page    (72) Inventor Takeshi Ashino             3-6-9 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo               Sumitomo Rubber Industries, Ltd. (72) Inventor Shuhei Mimura             3-6-9 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo               Sumitomo Rubber Industries, Ltd.

Claims (7)

[Claims] 1. A throat part, which connects a head part and a shaft part of a frame main body, is formed into a bifurcated shape, and a first yoke and a second yoke are provided between both side frames of the throat part.
A yoke and a head portion are connected to surround a ball striking face, and at least one of the first yoke and the second yoke is made of a material different from that of the frame body to absorb the vibration of the frame body, and at the same time as the first yoke. The gut holes provided in both of the second yokes and stretched on the ball striking surface may be stretched only through the gut holes of the first yoke or may be stretched in both of the first and second yokes. A tennis racket with a structure that allows you to choose whether to stretch it through. 2. A throat part, which connects a head part and a shaft part of a frame body, is formed into a bifurcated shape, and a first yoke and a second yoke are provided between both side frames of the throat part.
The yoke and the head portion are connected to surround the ball striking face, and at least one of the first yoke and the second yoke is mechanically bonded to the frame body or bonded via an adhesive, and the bonded interface is vibrated. A gut hole provided as an absorbing portion in both the first yoke and the second yoke and stretched on the ball striking face may be stretched only through the gut hole of the first yoke or may be stretched. A tennis racket having a configuration in which it can be selected to be stretched through both the gut holes of the second yoke and the second yoke. 3. A throat portion, which connects a head portion and a shaft portion of a frame body, is formed into a bifurcated shape, and a first yoke and a second yoke are provided between both side frames of the throat portion.
The yoke and the head portion are continuous to surround the ball striking face, and the gut holes are provided in both the first yoke and the second yoke. The gut stretched on the ball striking face is passed through only the gut hole of the first yoke. The structure is such that it can be stretched or stretched through the gut holes of both the first and second yokes, and at least one of the first and second yokes extends in the longitudinal direction. A tennis racket, characterized in that the vibration absorbing material having the above-mentioned gut holes provided in parallel with the existing fitting holes is fitted and fixed. 4. The tennis racket according to any one of claims 1 to 3, wherein both the first yoke and the second yoke are mechanically bonded or bonded to the frame body by an adhesive. 5. The first yoke and the second yoke are integrally molded via auxiliary frame portions arranged on the inner surfaces of both side frames of the throat portion, and are mechanically bonded or bonded to the frame body by an adhesive. The tennis racket according to any one of claims 1 to 3. 6. The tennis racket according to claim 1, wherein the gut hole of the first yoke is larger than the gut hole of the second yoke. 7. The first yoke and / or the second yoke is provided on its surface opposite to the ball striking face side with a protrusion for positioning and holding a gut to be bridged between adjacent gut holes. Item 7. The tennis racket according to any one of items 6.