JP2000070415A - Racket and manufacture of racket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve vibration attenuation properties of a racket york part. SOLUTION: A york 16 to connect right and left frame parts of the frame main body of a racket is constituted of fiber reinforced resin comprising reinforcing continuous fiber and matrix resin of thermoplastic resin. A connection reinforcing part 21 extended from the right and left end parts of the york 16 to at least one of the upper part of the stringing part side and the lower part of the throat part is equipped to form the connection reinforcing part integrally with right and left frame parts of the frame main body to constitute a part of right and left frame parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racket for ball games such as a tennis racket and a method for manufacturing a racket.
In particular, the yoke that connects the left and right frame portions that affect the vibration characteristics is improved to enhance the vibration damping property.

[0002]

2. Description of the Related Art In recent years, racket frames are made of fiber reinforced resin, and have become mainstream due to their light weight, high rigidity, high strength and durability. A general racket frame is reinforced with a fiber having high strength and a high elastic modulus such as carbon fiber, and is integrally formed from a thermosetting resin.
This racket frame made of thermosetting resin has high rigidity,
Although it has the advantage of high strength and good durability, it has a problem that when it is hit at the time of hitting a ball, vibration is likely to occur, and the player tends to be a tennis elbow.

For example, in a racket made of a fiber-reinforced thermosetting resin using carbon fiber, glass fiber, and aramid fiber as reinforcing fibers and using epoxy resin as a matrix resin, the vibration damping rate is as small as 0.5 or less.

A racket frame made of a fiber-reinforced thermoplastic resin is provided for the racket frame made of the fiber-reinforced thermosetting resin. The racket frame made of the fiber-reinforced thermosetting resin reflects the high toughness of the thermoplastic resin. It has impact resistance that cannot be obtained with a racket frame made of a curable resin, and the vibration damping rate is as large as 0.9 or more.

[0005] However, thermoplastic resins generally have a greater elasticity-dependent environment dependency than thermosetting resins, and there is a problem that the characteristics such as the rigidity of the racket frame tend to change depending on the use environment. Increasing the amount of reinforcing fibers to increase stiffness and strength increases the weight of the racket frame. In that case, in order to respond to a play style such as applying a spin, the operability of the racket is regarded as important, and it is not possible to respond by increasing the amount of reinforcing fiber because the weight of the racket frame is required to be reduced. .

As described above, in a racket made of fiber reinforced resin, whether the matrix resin is a thermosetting resin or a thermoplastic resin, there are advantages and disadvantages, light weight and high rigidity, It has been difficult to make a racket that satisfies all requirements of high strength and high vibration damping.

To solve the above problem, there has been proposed a racket frame in which a thermoplastic resin and a thermosetting resin are used in combination as a matrix resin. For example, in the racket frame described in JP-A-6-63183, a range X1 from the grip 1 to the center point P of the throat portion 2 is formed of a thermoplastic resin, as shown in FIGS. A range X2 of the gut stretch portion 3 surrounding the striking surface from the center point P of the throat portion is formed of a thermosetting resin, and a portion of the connection point at the position P is wound and connected to the fiber cloth sheet 4. .

[0008]

In a racket in which a thermoplastic resin and a thermosetting resin are combined as the matrix resin, the matrix resin, which is substantially half of the racket frame, is a thermoplastic resin, so that it is affected by the use environment. Not only is it easy, but there is a problem that the vibration mode of the racket is not taken into account and an effective vibration damping effect cannot be obtained.

That is, in the out-of-plane (in the thickness direction of the racket frame) vibration mode and the in-plane (in the width direction of the racket frame) vibration mode generated in the racket frame when hitting a ball, the left and right frame portions substantially at the center of the racket frame. Is a part of the antinode having a large vibration width. Therefore, even if a thermoplastic resin having excellent vibration damping properties is used as the matrix resin from the center in the length direction of the throat portion, which is displaced from the yoke, to the grip end, the vibration damping properties are low.

In a conventional racket, as shown in FIG. 12, the yoke 5 has a substantially rectangular parallelepiped shape having the same cross-sectional shape, and is joined to the inner surfaces of the left and right frame portions of the frame body 6 in abutting manner.
They are connected by bonding using an adhesive. If the connection is not firmly bonded, the durability of the racket cannot be maintained, but there is a problem that the bonding area is small.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems. Particularly, the present invention effectively reduces the damping rate of a racket frame while satisfying rigidity, surface stability of a hitting surface, and connection strength between a yoke and a frame body. The challenge is to increase it.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a racket in which a yoke connecting left and right frame portions of a frame body of a racket uses continuous fibers as reinforcing fibers and thermoplastic resin as a matrix resin. It comprises a fiber-reinforced resin, and has a connection reinforcing portion extending from at least the right and left ends to the upper side of the gut stretch portion side and the lower side of the throat portion to at least one of the upper and lower sides, and the connection reinforcing portion is a frame. A racket characterized by being formed integrally with the left and right frame portions of the main body to form a part of the left and right frame portions.

The above continuous fiber refers to a continuous fiber in a reinforcing fiber used in a fiber reinforced resin, and is usually 10 mm.
It is of the above length. In addition, a long fiber refers to about 1 mm, and a short fiber refers to about 0.5 mm. The yoke also includes a second yoke. In a racket including the second yoke, one or both of the second yoke and the first yoke have the above-described configuration.

In the above configuration, when the ball is hit, the yoke which becomes an antinode of the vibration and has a large amplitude under the influence of the bending in the out-of-plane vibration mode and the in-plane vibration mode is replaced with a thermoplastic resin having good vibration damping properties and a matrix resin. Because of this, vibration can be effectively attenuated. Moreover, since continuous fibers are used as the reinforcing fibers, the rigidity can be increased, and the vibration itself can be suppressed by giving the yoke which is the antinode of the vibrations a high rigidity. And the surface stability of the hitting surface can be increased.

In particular, since the yoke is provided with a connection assisting portion to increase the contact area with the frame main body and the connection assisting portion is integrally formed as a part of the frame main body at the time of molding the frame main body, the yoke and the frame main body are formed integrally. From this point, the high rigidity and high strength of the yoke can suppress the vibration width and contribute to the surface stability of the hitting surface.

The frame body is preferably formed from a fiber-reinforced thermosetting resin. That is, when the frame body is molded with a fiber-reinforced thermosetting resin, and only the yoke is made of a fiber-reinforced thermoplastic resin, environmental dependency can be reduced, and
It has high rigidity and high strength, and can improve resilience.

When the frame body is made of a fiber reinforced thermosetting resin and the yoke is made of a fiber reinforced thermoplastic resin as described above, the yokes are brought into contact with the left and right frame portions of the frame body and bonded with an adhesive as in the conventional case. If it is configured to be fixed, an adhesive for bonding the thermosetting resin and the thermoplastic resin becomes a problem, and in the case of abutting, since the bonding area is small as described above, the reliability of the connection and fixing becomes a problem. . To cope with this problem, connection assisting portions are provided at both left and right ends of the yoke to increase the contact area between the yoke and the frame main body.
Instead of bonding with an adhesive, when molding the frame body,
At the same time, since the connection assisting portion of the yoke is formed as a part of the frame body, the yoke and the frame body can be firmly connected.

The connection reinforcing portion of the yoke has a substantially U-shaped horizontal cross section, and is integrally formed by covering the inner surface and the front and rear side surfaces of the fiber molded body constituting each of the left and right frame portions of the frame body. The area of the portion where the part and the yoke are joined is 15 cm ² or more and 150 cm ² or less, the contact length in the length direction of the frame body is 50 mm or more, and the weight of the yoke is 15% to 35% of the weight of the racket frame. It is preferred that

As described above, when the joint portion with the left and right frame portions has a substantially U-shaped horizontal cross section, the inner surface and the front and rear side surfaces of each of the left and right frame portions can be brought into contact, and the contact area can be increased. it can. When the contact area is 15 cm ² or more, a sufficient bonding area can be obtained. Meanwhile, 1
If it is larger than 50 cm ^2, the portion to be joined to the frame main body becomes long, and the thermoplastic resin, which is easily affected by water absorption, undergoes dimensional change due to water absorption, so that the racket tends to be distorted and the strength is reduced.

The connection reinforcing portions at the left and right ends of the yoke extend up and down from the central connection portion to form a substantially H-shape as a whole, and are integrated with the upper gut tension portion and the lower throat portion to form a connection strength. Is preferably increased. In addition, it may have a substantially U shape extending only upward from the central portion and may be integrated only with the gut stretch portion, or may have a substantially inverted U shape extending only below and integrated only with the throat portion. May be.

The fiber reinforced resin constituting the yoke is a reinforced fiber made of carbon fiber, glass fiber, aramid fiber or the like, and a continuous fiber is used. The length of the continuous fiber of the connection reinforcing portion is set to 50 mm to 300 mm. Is preferred. As described above, when the length is 50 mm to 300 mm, the strength of the connection reinforcing portion joined to the frame main body can be further increased.

The form of the continuous fiber used for the yoke may be any of a braid, a plain-woven cloth, a unidirectional fiber sheet, a continuous strand mat, and a filament-wound continuous fiber. For example, sheets made of unidirectional fibers impregnated with a thermoplastic resin may be laminated and then molded by melting and heating, but it is preferable to use a woven fabric such as a blade or cloth. That is, in woven cloth,
Irregularities of the fibers occur in the molded article, and when joining with the frame body, an anchor function is generated by the irregularities, so that the connection strength can be further increased. As described above, a non-woven fabric obtained by filament-winding a commingled yarn can also be used, but a woven fabric such as a braid or cloth is preferable because the directionality of the fiber is not stable. Further, it is preferable to use the same material as the reinforcing fibers for forming the frame main body for the connection reinforcing portion integrated with the frame main body.

It is preferable that the center connecting portion of the yoke connecting the connecting reinforcing portions at the right and left ends is formed into a hollow shape from the viewpoint of weight reduction, and the hollow portion is filled with a foam such as urethane as a core.

As a method for forming the yoke, continuous fibers are used as the reinforcing fibers, so that a method of injection-molding a resin containing fibers cannot be adopted. A method in which a matrix is formed and a matrix resin is melted by applying a high internal pressure to mold the resin, and a method in which reinforcing fibers are previously arranged in a mold and a thermoplastic resin is reaction injection molded can be adopted. However, in the above method, since the molding temperature of the thermoplastic resin is high and the pressure is high, it is necessary to use a heat-resistant material such as a polyamide resin foam as the core to be filled in the hollow portion. further,
Due to the complex shape, it is very difficult to make the molding pressure uniform, voids are formed in the molded product, and the durability tends to decrease.

Therefore, the yoke used in the present invention is preferably formed by reaction injection molding. When the reaction injection molding method is used, a molded article having a complicated shape and made of a continuous fiber reinforced thermoplastic resin can be suitably molded. For example, when nylon is used as the matrix resin, the molding temperature can be kept low at around 150 ° C., and the injection pressure of the monomer can be as low as ³ to 7 kgf / cm ^3. Can be molded without crushing the foam. Therefore, a light-weight yoke having a high fiber content and a high rigidity can be obtained.

Considering the advantages of the vibration damping property of the thermoplastic resin and the environmental dependency of the disadvantages, the racket low frame (assembly of bumpers, grommets, grip leather, end caps, etc., lead for balance adjustment, grip members) And the weight of the thermoplastic resin is 15 to 35 w
It is preferably set to t%. The weight of the low frame includes the weight of the core filled in the hollow portion of the yoke.

Further, according to the present invention, the yoke connecting the left and right frame portions of the frame body of the racket is formed in advance from a fiber reinforced resin using continuous fibers as reinforcing fibers and a thermoplastic resin as a matrix resin. The present invention provides a method of manufacturing a racket in which the yoke is integrated with the frame body when the frame body is molded from a fiber-reinforced thermosetting resin.

As described above, the yoke preformed with the continuous fiber reinforced thermoplastic resin is filled into the yoke portion of the cavity of the mold for frame molding, and the other portion of the cavity is filled with the fiber reinforced thermosetting resin. The frame body is formed by filling the formed cylindrical body and heating the mold at a required temperature, and at the same time, the joint between the frame body and the yoke is integrally formed. in this way,
When the yoke and the frame main body are connected, the strength of the connecting portion between the yoke made of the thermoplastic resin matrix and the frame main body made of the thermosetting resin matrix is increased, and a racket with good durability can be obtained.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the tennis racket according to the present invention will be described below in detail with reference to the drawings.

The tennis racket frame 10 according to the first embodiment shown in FIG. 1 is a hollow, fiber-reinforced resin frame and surrounds a face surface S on which a gut is stretched from a single cylindrical frame body 11. Gut stretching part 12, throat part 13,
The shaft portion 14 and the grip portion 15 are configured continuously. The gut tension portion 12 is a yoke 1 made of a separate member.
6 is continuously formed on the throat side to form an annular shape surrounding the face surface S.

The frame body 11 is formed of a fiber reinforced thermosetting resin, and the yoke 16 is formed of a continuous fiber reinforced thermoplastic resin. The yoke 16 has a substantially H shape when viewed from the front, and integrally includes connection reinforcing portions 21, 21 extending from the left and right ends of the center connection portion 20 on the gut stretch portion 12 side and below the throat portion 12 side. It has a substantially H shape provided in an intended manner.

The yoke 16 has the shape shown in FIGS. 2, 3 and 4, and the center connecting portion 20 has a substantially rectangular frame shape.
0a is provided, and the hollow core 20a is filled with a core (not shown) such as urethane. The connection reinforcing portion 21 extending vertically from the left and right ends has a substantially U-shaped horizontal cross section, and the central portion 21a is formed on the inner surface (a) of the left and right frame portions of the frame main body 11.
The one side portion 21b is located on the front surface (b) of the frame main body, and the other side portion 21c is located on the rear surface (c) of the frame main body, and are integrally formed with the fiber reinforced resin constituting the frame main body 11, 11.

The area where each connection reinforcing portion 21 of the yoke 16 comes into contact with the frame body 11 should be 150 cm ² or more and 150 mm.
cm ² or less. In addition, the length of the continuous fiber constituting the connection reinforcing portion 21 is not less than 50 mm and not more than 300 mm.

In the racket frame, the yoke 16 is formed in advance and filled in the yoke portion of the cavity of the racket frame forming die, while the other cavities are made of fiber reinforced material which is a material for forming the frame body. A cylindrical laminate made of a thermosetting resin sheet is filled, and in this state, a mold is heated at a required temperature to form a low frame of a racket. The weight of the molded product of the yoke is set in the range of 15% to 35% of the weight of the low frame of the racket.

Example 1 A tennis racket frame according to the present invention was manufactured. First, a yoke was formed in the following procedure. The core of the yoke was made of urethane foam (made by Dainippon Ink). An 80 μm-thick 66 nylon tube was placed over the outer periphery of the core, and both ends of the tube were heated and melted and sealed while reducing the pressure so that air did not remain in the tube and the urethane foam of the core. After that, a braid made of carbon fiber woven in a sleeve shape around the outer circumference of the tube (Toray carbon braid, TX364A, fiber angle 24 °,
φ20 and TX364B, fiber angle 45 °, φ20 each 2
Layers) were stacked to create a lay-up at the center connection of the yoke. In addition, the connection reinforcing portions provided at the left and right ends of the yoke are made of carbon fiber braid (TX364B (45)
°, φ20). The center of the substantially H-shaped cavity of the yoke molding die was filled with the lay-up of the central connecting portion, and both sides of the cavity were filled with the lay-up of the connecting reinforcing portion.

The temperature of the yoke molding die was raised to 150 ° C., and a molten nylon monomer (UX-75 manufactured by Ube Industries) was injected into the cavity. The nylon monomer had a melting temperature of 90 ° C., and was injected by mixing a liquid A containing a catalyst and a liquid B containing an initiator at a ratio of 1: 1. Injection pressure is 5kg
The mold was released after holding at f / cm ³ for 3 minutes.

The molded product to be the yoke has the shape shown in FIGS. 2 to 4 and has a cross-sectional shape having a thickness of 24 mm and a width of 13 to 15 mm, and has a hitting area (face area) of 110 inches. And a length corresponding to the length of the yoke connecting the two. The weight of the molded product serving as the yoke was 48 g, the vertical length of the connection reinforcing portion connected to the frame body was 90 mm, and the contact area of the connection reinforcing portion with the frame body was 45 cm ² .

On the other hand, to construct the frame body, φ1
A 4.5 mandrel is placed on a 66 nylon tube, and a carbon fiber prepreg impregnated with epoxy resin (T800, T800, P2053, resin impregnation amount 30%) is laminated on the outer periphery of the tube, and a vertical laminate is formed. Created.
The fiber angle of the prepreg is 0 ° (two layers), 22 ° (1
Layers), 30 ° (two layers), and 90 ° (one layer), and six sheets were laminated to form a lay-up of the frame body.

The lay-up of the frame body and the lay-up of the yoke were filled in the cavities of the racket frame molding die. At this time, the connection reinforcing portion of the yoke was put on the inner surface and the front and rear side surfaces of the lay-up of the frame body. Further, 15 g of carbon fiber prepreg was wrapped around the connection between the frame body and the yoke to reinforce the connection.

The above-mentioned racket frame molding die was set to 150
After heating to ° C. and holding for 40 minutes, the mold was released and the molded product was taken out. In the molded product, at the connection portion between the frame body and the yoke, the connection reinforcing portion of the yoke is integrally formed as a part of the left and right frame portions of the frame body. The connection reinforcing portion of the yoke has a surface that is smoothly continuous with the left and right frame portions of the frame main body, and has no step so as to be a part of the left and right frame portions of the frame. The molded racket frame (low frame) weighed 210 g.

(Embodiment 2) The difference from Embodiment 1 is that the number of laminated carbon fiber blades constituting the yoke is increased from that of Embodiment 1 so that the weight of the molded yoke is 66 g and the frame body is The number of laminated carbon fiber prepregs was reduced. The weight of the molded raw frame was 202 g.

(Embodiment 3) The difference from Embodiment 1 is that the number of laminated carbon fiber blades constituting the yoke is reduced from that of Embodiment 1, the weight of the molded yoke is 34 g, and the frame body is The number of laminated carbon fiber prepregs was increased. The weight of the molded raw frame was 203 g.

(Embodiment 4) The yoke molding die was changed from that of Embodiment 1 so that the length of the connecting reinforcing portion where the connecting reinforcing portion was in contact with the frame main body was 60 mm, and the contact area with the frame main body was 18 cm ² . Was used. Others were the same as Example 1. The weight of the molded yoke was 45 g, and the weight of the molded low frame was 201 g.

For comparison with the above embodiment, racket frames of the following comparative examples 1 to 4 were prepared.

(Comparative Example 1) The difference from Example 1 is that the number of laminated carbon fiber blades constituting the yoke is increased from that in Example 1 so that the weight of the molded yoke is 78 g while the frame body is The number of laminated carbon fiber prepregs was reduced. The weight of the molded raw frame was 204 g. That is, the yoke weight is 38% of the low frame weight
In this case, the value exceeded 35% of the preferable range.

(Comparative Example 2) The difference from Example 1 is that the number of laminated carbon fiber blades constituting the yoke is reduced from that in Example 1, and the weight of the molded yoke is 26 g, while the frame body is The number of laminated carbon fiber prepregs was increased. The weight of the molded raw frame was 202 g. That is, the yoke weight is 12% of the low frame weight
To less than 15% of the preferred range.

(Comparative Example 3) The mold for yoke molding was changed from that of Example 1 so that the length of the connecting reinforcing portion where the connecting reinforcing portion was in contact with the frame main body was 46 mm, and the contact area with the frame main body was 13 cm ² . Was used. Others were the same as Example 1. The weight of the molded yoke was 43 g, and the weight of the molded low frame was 202 g. That is, the length of the connection reinforcing portion was made smaller than the preferred range of 50 mm, and the contact area was made smaller than the preferred range of 15 cm ² .

(Comparative Example 4) The same racket frame molding die as in Example 1 was used. The material of the yoke was a conventional general one, and unexpanded polystyrene was inserted into a 66 nylon tube to form a core. Carbon fiber prepreg (T800, P2053, manufactured by Toray Co., Ltd., 30% impregnation amount of thermosetting resin), which is the same material as the frame body, is laminated on the outer periphery of the tube, and further, 15 g of carbon is adhered to the frame body. Fiber prepreg reinforcement was added. The shape of the yoke is the same as that of the first embodiment, and a connection reinforcing portion is provided.
m, and the contact area was 45 cm ² . That is, although the shape was the same as that of Example 1, the yoke was molded with a fiber-reinforced thermosetting resin. The weight of the molded low frame was 200 g.

The tennis rackets of Examples 1 to 4 and Comparative Examples 1 to 4 were prepared three by three, and with each gut stretched, the top pressure strength, the out-of-plane primary vibration damping rate,
An in-plane vibration damping rate and durability test were performed. The results are shown in Table 1 below.

[0050]

[Table 1]

As shown in FIG. 5, the top pressure strength was measured by vertically arranging the racket on which the gut was stretched with the top (12:00) as the upper end, holding and fixing both sides,
A load was applied at a speed of 0 mm / min, and the load value at break was measured.

As shown in Table 1, in Examples 1 to 4, the peak pressure strength was 119 to 107 kg / cm, the peak pressure strength was large, and the in-plane stability of the face face hitting the ball was excellent. Was confirmed. On the other hand, in Comparative Example 1 in which the number of prepregs in the frame body was reduced, the peak pressure strength was low at 90 kg / cm. In Comparative Example 3 in which the length of the connection reinforcing portion of the yoke was set to 46 mm of 50 mm or less and the contact area was set to 13 cm ² smaller than 15 cm ² , the peak pressure strength was 90 k.
g / cm. It was confirmed that the comparative examples 1 and 3 having a low top pressure strength were damaged in the durability test described later, and were inferior in strength and durability.

As shown in FIG. 6, the measurement of the out-of-plane primary vibration damping rate is performed by hanging the top of the racket with a string and freely supporting the racket. In this state, the acceleration pickup 100 is attached to one side of the 5 o'clock position. Vibration was applied from the back side with an impact hammer 101. The input vibration measured by the force pickup attached to the impact hammer and the response vibration measured by the acceleration pickup were analyzed by the frequency analyzer 104 via the amplifiers 102 and 103. The transfer function in the frequency domain was obtained by this analysis, and the out-of-plane primary natural frequency was obtained. The attenuation rate was obtained from FIG.

Ζ = (１ ／) × (△ ω / ωn) T0 = Tn / √2

As shown in Table 1, the out-of-plane primary vibration damping rates of Examples 1 to 4 were 0.69 to 0.78. Comparative Example 2 in which the weight of the yoke was less than 15% of the low frame weight was 0.48, and the vibration damping property was poor. In Comparative Example 4 in which the matrix resin of the yoke was a thermosetting resin, the vibration damping property was poor at 0.36.

As shown in FIG. 8, the measurement of the in-plane vibration damping rate is performed by fixing the grip end of the racket frame, suspending the racket frame downward, mounting the acceleration pickup 100 at the 3 o'clock position, and setting the impact hammer 101 from the back surface. Excited. The input vibration measured by the force pickup attached to the impact hammer and the response vibration measured by the acceleration pickup were analyzed by a frequency analyzer via an amplifier. This analysis finds the transfer function in the frequency domain,
The in-plane natural frequency was obtained. The damping rate was obtained from FIG. 7 by the above equation in the same manner as the out-of-plane primary natural frequency.

As shown in Table 1, the in-plane vibration damping rates of Examples 1 to 4 were 0.71 to 0.78. On the other hand, Comparative Example 2 was 0.52 and Comparative Example 4 was 0.33, and the in-plane vibration damping rate was also poor.

In the endurance test, the gut tension was
With the tennis racket having the warp 651b × the weft 601b in a free state, a ball was hit at 55 m / sec. The ball collision positions were a position 6 cm above the yoke and a position 6 cm below the top. Each of the balls was hit 1000 times, and the number of damaged balls was measured.

As shown in Table 1, none of Examples 1 to 4 was damaged. On the other hand, in Comparative Example 2 in which the vibration damping rate was excellent, all three rackets were broken at the top position. Similarly, in Comparative Example 4 in which the vibration damping rate was excellent, two of the three rackets were damaged at the connection between the yoke and the frame body.

As described above, when the matrix resin of the fiber reinforced resin constituting the yoke is made of a thermoplastic resin in various tests, it can be seen that the damping rate is good for both out-of-plane primary vibration and in-plane vibration. It could be confirmed. In addition, a connection reinforcing portion is provided on the yoke, and a contact length with the frame body is set to 50.
mm or more, the contact area is 15 cm ² or more, and the yoke weight is 15% to 35% of the low frame weight.
It was confirmed that the strength and durability were excellent.

In the above-described embodiment and experimental example, the connection reinforcing portion 21 provided on the yoke 16 is extended to the upper and lower sides of the gut stretch portion side and the throat portion side, and the yoke is formed in a substantially H shape. As shown in FIG. 9A of the second embodiment, the connection reinforcing portion 21 may be extended only above the gut stretch portion side, and the entire yoke may be substantially U-shaped. Alternatively, as shown in FIG. 9 (B), the connection reinforcing portion 21 may be extended only toward the throat portion to form a substantially inverted U-shape.

Further, in the above-described embodiment, only one yoke 16 is provided as a member for connecting the left and right frame portions of the frame main body. As shown in FIG. The second yoke 16 'is also formed of a continuous fiber-reinforced thermoplastic resin similar to the first yoke 16, and the connection reinforcing portions 2 are provided at both left and right ends of the central connecting portion 20'.
1 'is provided, and a connection reinforcing portion 21' is provided on the left and right frame portions of the throat portion.
May be brought into contact to be integrally molded.

In the case where there are two yokes, a first yoke and a second yoke, only one of the yokes is formed of a connecting fiber-reinforced thermoplastic resin, and a connecting reinforcing portion is provided at both ends thereof. The other one may use the same thermosetting resin as the conventional resin as the matrix resin. Furthermore, even when the frame body is made of a matrix resin of a thermoplastic resin, the connection strength with the frame body can be increased by providing the yoke with the connection reinforcing portion.

[0064]

As is apparent from the above description, the racket according to the present invention uses the continuous fiber reinforced thermoplastic resin for the yoke at the position of the anti-vibration in both the out-of-plane vibration and the in-plane vibration and at the position where the amplitude is large. With this configuration, both the out-of-plane vibration damping rate and the in-plane vibration damping rate can be increased, resulting in a racket having excellent vibration damping characteristics. Therefore, unpleasant vibration transmitted to the player can be suppressed, and the shot feeling can be improved.

Moreover, since the yoke is made of continuous fiber and provided with a connecting reinforcing portion at the connecting portion with the frame main body to increase the contact length and the contact area of the frame main body, the thermoplastic resin is used as the matrix resin. In addition, the strength and rigidity can be increased, and it can be firmly connected to the frame body. In this way, by increasing the strength and rigidity, the surface stability of the hitting surface can be maintained,
The controllability of the ball can be improved.

Further, when the matrix resin of the yoke is made of a thermoplastic resin and the matrix resin of the frame body is made of a thermosetting resin, the strength and rigidity of the entire frame can be increased, thereby increasing the amount of reinforcing fibers. Without doing so, the weight can be reduced. Therefore, it is possible to provide a light-weight racket with good operability while having high strength, high rigidity, and a high vibration damping rate.

[Brief description of the drawings]

FIG. 1A is a plan view showing a tennis racket frame according to a first embodiment of the present invention, and FIG. 1B is a perspective view of a main part.

FIG. 2 is a perspective view showing a yoke.

FIG. 3 is a plan view of the yoke.

4A and 4B show cross sections of the yoke, wherein FIG. 4A is a cross-sectional view taken along line AA of FIG. 3, FIG. 4B is a cross-sectional view taken along line BB of FIG.
3 (C) is a cross-sectional view taken along the line CC of FIG. 3, and FIG.
It is a line sectional view.

FIG. 5 is a drawing showing a method of measuring a peak pressure strength.

FIG. 6 is a view showing a method of measuring an out-of-plane vibration damping rate.

FIG. 7 is a diagram showing a relationship between a frequency and a transfer function.

FIG. 8 is a drawing showing a method of measuring an in-plane vibration damping rate.

FIGS. 9A and 9B are schematic diagrams showing a second embodiment.

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

11A and 11B are diagrams showing a conventional example.

12A and 12B are diagrams showing another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Tennis racket 11 Frame main body 12 Gut stretch part 13 Throat part 16 Yoke 20 Central connection part 21 Connection reinforcement part

Claims (4)

[Claims] 1. A yoke connecting the left and right frame portions of a frame body of a racket is made of a fiber reinforced resin having continuous fibers as reinforcing fibers and a thermoplastic resin as a matrix resin. A connection reinforcing portion extending at least one of upper and lower sides above the tension portion side and below the throat portion side, and the connection reinforcing portion is integrally formed with the left and right frame portions of the frame body to form one of the left and right frame portions; A racket comprising a part. 2. The racket according to claim 1, wherein the frame body is made of a fiber-reinforced thermosetting resin. 3. A contact area of the connection reinforcing portion of the yoke with each of the left and right frame portions of the frame main body is one.
5 cm ² or more 150 cm ² or less, contacting at least 50mm in length, in and yoke weight of the racket frame weight 1
The racket according to claim 1 or 2, wherein the racket is 5% to 35%. 4. A yoke for connecting the left and right frame portions of the frame body of the racket is formed in advance with a fiber reinforced resin using continuous fibers as reinforcing fibers and a thermoplastic resin as a matrix resin. A method of manufacturing a racket, wherein the yoke is integrated with a frame body when molding from a reinforced thermosetting resin.