JP2003175134A - Tennis racket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve not only surface stability, operability and controllability but also the resilience of a tennis racket, and moreover, realize a lighter weight. <P>SOLUTION: The weight of a racket frame should be 100 g or more to 280 g or less, the value of rigidity (G1) thereof outward from the ball hitting surface be 1568 N/cm or more to 2156 N/cm or less, the value of rigidity (G2) thereof inward to the ball hitting surface be 784 N/cm or more to 1274 N/cm or less and the ratio of the (G1) to (G2), (G1/G2), be 1.5 or more to 2.4 or less while the moment of inertia (Is) in the direction of swinging be 440,000 g.cm<SP>2</SP>or more to 520,000 g.cm<SP>2</SP>or less and the moment of inertia (Ic) in the direction of the center be 13,500 g.cm<SP>2</SP>or more to 17,000 g.cm<SP>2</SP>or less and (Is/Ic) be 28 or more to 36 or less. <P>COPYRIGHT: (C)2003,JPO

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, it is used for a lightweight hard tennis racket and is intended to improve the resilience performance and control performance.

[0002]

2. Description of the Related Art In recent years, a so-called "thick racket" having a thickness in the out-of-plane direction of a ball striking face of a racket frame has been provided. A user who needs such a thick racket is a layer that requires flight performance with less force, such as a female or senior layer, and a tennis racket that is lightweight and has good flight performance is required. Furthermore, among women and seniors, tennis rackets with excellent control performance are required for players with strong competitive thinking.

However, from the viewpoint of collision between the two objects, the racket frame and the ball, the restitution coefficient of the ball decreases as the racket frame becomes lighter according to the law of conservation of energy. Therefore, reducing the weight of the racket frame leads to a reduction in the resilience performance.

To maintain the resilience performance of a racket frame in a conventional lightweight tennis racket weighing less than 280 g,
It is common practice to increase the value of balance, which is the distance from the grip end to the center of gravity of the racket frame, to maintain the moment of inertia in the swing direction.

Further, in order to solve the deterioration of the resilience performance due to the reduction in weight of the racket frame, the applicant of the present invention has disclosed in Japanese Patent Laid-Open No. 11-57074 that an out-of-plane direction (a ball collides in the thickness direction of the racket frame). We propose a racket frame with improved repulsion performance by setting the ratio of the primary natural frequency in the in-plane direction (the direction orthogonal to the out-of-plane direction) within a predetermined range.

[0006]

However, when the balance value is increased and the moment of inertia in the swing direction is maintained as described above, a repulsive performance can be maintained, but swinging is poor and a powerless woman or It is a racket frame with poor operability for seniors. Further, the rigidity (in-plane direction, out-of-plane direction) of the ball striking face becomes low, and the ball striking face is easily deformed, so that there is a problem that the surface stability is poor and the control performance is deteriorated.

Further, even in the above racket frame proposed by the applicant of the present invention, although it has been possible to enhance the resilience performance of the racket frame, it has been found that there is room for improvement in control performance. That is, the racket frame has improved repulsion performance by focusing on the primary natural frequency in the out-of-plane direction and the in-plane direction. It was found that the primary vibration in the direction was excited when the ball was hit without the sweet spot. However, since players usually hit the ball near the sweet spot,
We found that it is more effective to improve the resilience performance by focusing on the secondary vibration in the out-of-plane direction that is excited when the ball is hit near the sweet spot.

The present invention has been made in view of the above problems, and in a lightweight racket (weight 280 g or less and 100 g or more), the resilience performance is improved when hitting a ball, and the hitting surface is stabilized. Therefore, the challenge is to improve control performance.

[0009]

In order to solve the above problems, the present invention firstly provides a tennis racket comprising a racket frame made of fiber reinforced resin, wherein the weight of the racket frame is 100 g or more and 280 g or less. , The absolute value | F1-F2 | of the difference between the secondary natural frequency (F1) of the striking face in the out-of-plane direction and the natural frequency (F2) of the string is 0H.
Provided is a tennis racket which is characterized in that the frequency is set to z or more and 100 Hz or less.

The above tennis racket was made based on the results of experiments including the inventor's earnest research and trial hitting test. To improve the resilience performance of a lightweight tennis racket, the natural frequency of the string and It is based on the finding that it is effective to bring the secondary natural frequencies in the out-of-plane direction close to each other.

The resilience performance is improved when the natural frequency of the string and the secondary natural frequency in the out-of-plane direction are close to each other.
It is considered that this is because the position of the string and the position of the out-of-plane secondary vibration mode match. Since the vibration mode of the out-of-plane secondary vibration waveform and the vibration waveform of the string are the same in the range of the ball striking face of the racket, the resilience performance becomes large. That is, by matching the secondary natural frequency in the out-of-plane direction with the natural frequency of the string (impedance matching), energy loss is suppressed and the resilience performance is improved.

In the conventional general racket frame, the secondary natural frequency in the out-of-plane direction is 350 Hz to 510 Hz, and the secondary natural frequency in the out-of-plane direction is a string (gut) suspended on the racket. It was measured in the absence. However, since the string is stretched when actually playing, it is necessary to consider the natural frequency of the string stretched in order to improve the resilience performance. However, the string is usually 45 lbs to 55
When the secondary natural frequency of the racket frame in the out-of-plane direction is measured with the string stretched by lbs, the secondary natural frequency in the out-of-plane direction is 2 to 3% as compared with when the string is not stretched.
It turns out that it only decreases. This tendency is the same when the tension of the string is widened to 40 lbs to 70 lbs.

As described above, the secondary natural frequency in the out-of-plane direction slightly decreases when the string is stretched, but when the natural frequency of the string and the secondary natural frequency in the out-of-plane direction are brought close to each other, the string The difference due to the presence or absence is substantially in a negligible range. Therefore, in the present invention, the secondary natural frequency (F1) in the out-of-plane direction is a value in the state without strings. When the string is stretched with a normal tension of 45 lbs to 55 lbs, the natural frequency of the string is 500 Hz to 600 Hz.

In the present invention, the secondary natural frequency (F1) in the out-of-plane direction is set to 480 Hz to 600 Hz, preferably 500 Hz to 580 Hz. Thereby, the natural frequency of the string and the secondary natural frequency in the out-of-plane direction are close to each other, and the resilience performance can be improved. The above range has a problem that if F1 is less than 480 Hz, it does not match the natural frequency of the string and the resilience performance deteriorates. Similarly, if F1 is greater than 600 Hz, the natural frequency of the string is the same. This is because there is a problem that the repulsion performance is deteriorated because it does not match with.

The absolute value of the difference between the secondary natural frequency (F1) in the out-of-plane direction and the natural frequency (F2) of the string | F1-
F2 | is, as described above, 0 Hz or more and 100 Hz or less,
It is preferably 0 Hz or more and 80 Hz or less, and more preferably 0 Hz or more and 40 Hz or less. In this way, by limiting the difference between the secondary natural frequency (F1) of the racket frame in the out-of-plane direction and the natural frequency (F2) of the string and bringing them closer to each other, the resilience performance can be further improved. . The smaller the value of | F1-F2 | is, the better the resilience performance is, and if the value of | F1-F2 | is greater than 100 Hz, the energy loss is large and the resilience performance is poor.

Secondly, the present invention is a tennis racket comprising a racket frame made of fiber reinforced resin, wherein the racket frame has a weight of 100 g or more and 280 g or less, and a rigidity value (G1) in the out-of-plane direction of the hitting surface. ) 1568
N / cm or more and 2156 N / cm or less, and the rigidity value (G2) in the in-plane direction of the ball striking surface is 784 N / cm or more and 1274 N / c
m or less, and the ratio (G1 / G) of (G1) and (G2)
The tennis racket is characterized in that 2) is 1.5 or more and 2.4 or less.

Thirdly, a tennis racket composed of a fiber-reinforced resin racket frame, wherein the racket frame has a weight of 100 g or more and 280 g or less, and the secondary natural frequency (F1) in the out-of-plane direction of the ball striking face. And a rigidity value (G1) of the ball striking surface in the out-of-plane direction are 1568 N / cm or more and 2156 N / cm or less.

The above-mentioned second and third tennis rackets are also made based on the results of experiments including the inventor's earnest research and trial hit test, and in order to improve the control performance of a lightweight tennis racket, Based on the finding that it is effective to improve the rigidity value of the striking surface (out-of-plane direction, in-plane direction), especially the in-plane direction rigidity (lateral pressure rigidity) value, and increase the surface stability. .

The tennis racket of the present invention most preferably has the above-mentioned first, second and third constructions. That is, the rigidity value (G1) in the out-of-plane direction of the ball striking surface is 1568 N / cm or more and 2156 N / cm or less, the secondary natural frequency (F1) in the out-of-plane direction is 480 Hz or more and 600 Hz or less, and the rigidity in the in-plane direction of the ball striking surface. Value (G2) of 784 N / cm or more 1274
N / cm or less, the ratio of (G1) and (G2) (G1 / G
2) in the range of 1.5 or more and 2.4 or less, and the absolute value | F1-F2 | of the difference between the natural frequency (F2) of the string stretched on the ball striking face and the above (F1) is set to 0 Hz or more and 100 Hz or less. is doing.

Regarding the secondary natural frequency in the out-of-plane direction which affects the improvement of the resilience performance, the rigidity of the ball striking surface (in-plane direction, out-of-plane direction) and the shaft portion are greatly involved, and further the racket frame weight is also involved. To do. Therefore, it is necessary to adjust the rigidity and the racket frame weight so that the secondary natural frequency in the out-of-plane direction matches the natural frequency of the string. On the other hand, the surface stability that contributes to control performance is
It is important to improve the rigidity of the entire frame, especially by increasing the rigidity of the ball striking surface (in-plane direction, out-of-plane direction), and above all, it is important to increase the in-plane direction rigidity (lateral pressure rigidity). Therefore, in order to obtain a tennis racket having both resilience performance and control performance, it is particularly necessary to appropriately set the hitting surface rigidity (out-of-plane direction of hitting surface) and lateral pressure rigidity (in-plane direction of hitting surface). . In the present invention, the striking surface rigidity and the lateral pressure rigidity are set to the above-mentioned settings, thereby making it possible to improve both the resilience performance and the control performance.

The hitting surface rigidity (rigidity in the out-of-plane direction of the hitting surface) value (G1) is 1568 N / cm or more and 21 as described above.
It is set to 56 N / cm or less. Preferably 1666 N /
cm or more and 2058 N / cm or less. This is (G
If 1) is less than 1568 N / cm, there is a problem that the repulsion performance is deteriorated because no matching occurs, and (G1)
Is more than 2156 N / cm, the repulsion performance is deteriorated because no matching is performed, and a large amount of high elastic yarn is used, resulting in a problem that strength is reduced.

Further, the lateral pressure rigidity (rigidity in the in-plane direction of the ball striking face) (G2) is set to 784 N / cm or more and 1274 N / cm or less as described above. Preferably 882N
/ Cm or more and 1176 N / cm or less. The larger (G2), the better the surface stability and the better the control performance, but the above range is set for the following reasons. This is because if (G2) is less than 784 N / cm, the surface stability is poor and the control performance is reduced, and (G2) is 1274 N.
This is because if it is larger than / cm, the racket weight becomes heavy and the strength becomes insufficient.

The ratio (G1 / G2) of the hitting surface rigidity value (G1) and the lateral pressure rigidity value (G2) is 1.5 or more and 2.4 or less, preferably 1.7 or more and 2.2 or less, and more preferably. It is set to 1.8 or more and 2.1 or less. This is G1 / G
When the value of 2 is smaller than 1.5, there is a problem that the resilience performance is deteriorated, and when the value of G1 / G2 is larger than 2.4,
This is because there is a problem that controllability is reduced.

Conventionally, it was difficult to increase the lateral pressure rigidity value (G2) as compared with increasing the hitting surface rigidity value (G1), so that the above G1 / G2 was a relatively large value. However, in the present invention, as will be described later, the racket frame is made of fiber reinforced resin, the portion where the fiber angle is 0 degree or more and 10 degrees or less is relatively frequently used, and the tensile elastic modulus is high such as 35t or more and 45t or less. The rigidity value is achieved by using seeds.

The tennis racket of the present invention is a lightweight racket frame of 100 g or more and 280 g or less, in order to impart the above-mentioned physical property values, in order to impart the above-mentioned physical property values, a part of the head portion and the throat portion surrounding the ball striking face of the racket frame is provided with tensile strength of the reinforcing fiber. The elastic modulus is 35t or more and 45t or less, the fiber angle of the reinforcing fiber is 0 degree or more and 10 degrees or less with respect to the length direction (axial direction) of the racket frame, and / or the maximum thickness of the head portion is 26 mm to 30 mm and the maximum width is 13 mm-16
mm.

The racket frame weight is as described above.
It is 100 g or more and 280 g or less. Preferably 2
It is not less than 00 g and not more than 260 g. This is because if the racket frame weight is less than 100 g, the racket strength is insufficient, and if it is more than 280 g, it is against the weight reduction of the racket.

The racket frame is preferably formed by forming a laminate of fiber reinforced prepregs into a hollow pipe shape. In the racket frame having this structure, in order to obtain the above-mentioned ball striking surface rigidity value, lateral pressure rigidity value, and secondary natural frequency in the out-of-plane direction, the cross-sectional shape of the racket frame, the fiber type (tensile elastic modulus), and the reinforcing fiber of the reinforcing fiber. The fiber angle, laminated structure, etc. of are set as above.

Specifically, the tensile elastic modulus of the reinforcing fiber is set to 35t or more and 45t or less in a part of the head portion and the throat portion surrounding the ball striking surface of the racket frame. Usually, a fiber type having a tensile elastic modulus of about 24t to 30t is often used as a reinforcing fiber, but the rigidity value can be increased by making the tensile elastic modulus relatively large. The reason for setting the above range is that sufficient elasticity cannot be obtained when the tensile elastic modulus is less than 35 t, and when the tensile elastic modulus is more than 45 t, the strength of the fiber itself is lowered and the openability is deteriorated. This is because when a prepreg is used, the weight per unit area increases and the weight reduction cannot be maintained.

The tensile elastic modulus of the reinforcing fiber is 35t or more and 45t or more.
The following fiber reinforced prepreg has a racket frame with the head part as the clock face and the top position as 12 o'clock,
It is preferable to arrange within the range of 2 to 4 o'clock and 8 to 10 o'clock.

The fiber angle of the reinforcing fibers in the part of the head portion and the throat portion surrounding the ball striking face of the racket frame is set to 0 ° or more and 10 ° or less with respect to the length direction (axial direction) of the racket frame. When the fiber angle (orientation angle) of the reinforcing fiber is 0 degrees or more and 10 degrees or less with respect to the length direction (axial direction) of the racket frame, the rigidity in the in-plane direction is efficiently improved, and 40 degrees or more and 50 degrees or less. When set to, the rigidity in the out-of-plane direction is efficiently improved. In order to maintain the rigidity of both, 20 degrees or more and 30 degrees or less is suitable. In the present invention, a fiber reinforced prepreg having a fiber angle of 0 degree or more and 10 degrees or less is frequently used in order to improve the rigidity in the in-plane direction and enhance the control performance.

The fiber reinforced prepreg in which the fiber angle of the reinforcing fiber is 0 ° or more and 10 ° or less is 2 o'clock to 4 o'clock, 8 o'clock when the top position is 12 o'clock when the head part of the racket frame is viewed as the watch face. It is preferable to arrange it within the range of 10 o'clock.

With respect to the laminated structure of the fiber reinforced prepreg, it is preferable that prepregs such as high elasticity yarns are intensively arranged at the apexes of the racket frame cross section in the out-of-plane direction. This makes it possible to improve both the hitting surface rigidity value and the lateral pressure rigidity value.

Regarding the cross-sectional shape of the racket frame,
The greater the thickness and width in the out-of-plane direction and the in-plane direction, the greater the respective rigidity values. Regarding the thickness of the racket frame, as described above, the maximum thickness is 26 mm or more and 30
mm or less is preferable. This is because if the maximum thickness is less than the above range, sufficient rigidity cannot be obtained, and if the maximum thickness exceeds the above range, the strength decreases, and if the strength is maintained, the weight increases and the operability is reduced. This is because it becomes bad. For the same reason as above, the maximum width of the racket frame is preferably 13 mm or more and 16 mm or less.

A numerical value MI obtained by multiplying the weight of the racket frame by the distance (balance) from the grip end to the position of the center of gravity is 82000 g · mm or more and 92000 g · mm or less, preferably 84000 g · mm or more and 90000 g ·
mm or less. This has an MI of 82000 gm
If it is smaller than m, the racket frame is too light, and there is a problem that the ball does not fly at the time of hitting, and MI is 92.
This is because if it is larger than 000 g · mm, the racket frame is heavy and swinging becomes poor.

Inertia model in the swing direction of the racket frame
(Swing outside the striking surface with the grip end as the fulcrum
Moment of inertia) (Is) is 440000g
cm ^TwoMore than 520,000g · cm^TwoBelow, preferably 4
60,000 g · cm^TwoMore than 500000g · cm^TwoLess than
I am trying. This is Is 440000g · cm^TwoYo
If it is too small, the racket frame will be too light and the ball will fly.
There is a problem that it is bad, and Is is 520,000 g · cm
^TwoIf it is larger, the racket frame is heavy and swings out
This is because there is a problem that it gets worse.

Moment of inertia in the direction of the center of the racket frame (moment of inertia about the central axis of the grip)
(Ic) of 13500 g · cm ² or more and 17,000 g · c
m ² or less, preferably 14000 g · cm ² or more and 165
It is set to 00 g · cm ² or less. This has an Ic of 135
If it is less than 00 g · cm ² , there is a problem that the racket frame is too light and the ball does not fly, and Ic is 17
This is because if it is larger than 000 g · cm ² , the racket frame is heavy and it is difficult to swing it out.

The moment of inertia in the swing direction (I
s) and the moment of inertia (Ic) in the center direction (I)
s / Ic) is 28 or more and 36 or less, preferably 30 or more and 3
It is 4 or less. It has been known that the flight performance is affected by the moment of inertia, especially the moment of inertia in the center direction. The larger the moment of inertia in the center direction, the better the flight performance. On the other hand, if the ratio Is / Ic with the moment of inertia in the swing direction becomes smaller, the laminated structure of the fiber reinforced prepreg becomes unbalanced and the strength is weak. Become. On the contrary, it has been found that the weight of the racket frame becomes heavy when Is / Ic becomes large. Therefore, Is / Ic is within the above range.

As the above-mentioned fiber reinforced prepreg, a fiber reinforced prepreg in which reinforcing fibers are carbon fibers and which is impregnated with a thermosetting resin (epoxy resin) is preferably used. As the reinforcing fiber, in addition to carbon fiber, aramid fiber, boron fiber, aromatic polyamide fiber, aromatic polyester fiber, and ultra-high molecular weight polyethylene fiber are used.

Further, the present invention is not limited to a racket frame composed of a laminate of fiber reinforced prepregs, and a reinforcing fiber is wound around a mandrel by filament winding to form a layup, which is placed in a mold. It can also be applied to a racket frame formed by filling a thermoplastic resin such as rim nylon.

[0040]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 3 show a tennis racket 1 according to the first embodiment, in which a racket frame 2 has a striking face F.
The head portion 3, the throat portion 4, the shaft portion 5, and the grip portion 6 surrounding the are continuously configured. The head unit 3 is
The yoke 7, which is a separate member, is continuous with the racket frame 2 on the throat side and has an annular shape surrounding the ball striking face F.

The racket frame 2 is composed of a hollow pipe made of fiber reinforced resin and is made of a laminate of fiber reinforced prepregs in which carbon fibers are impregnated with epoxy resin which is a matrix resin.

The total length L from the top of the head 3 to the tip of the grip 6 is 700 mm, the racket frame weight is 265 g, and the balance point is 339 mm from the tip of the grip 6. In the cross section of the head portion 3 (excluding the yoke 7) and the throat portion 4 of the racket frame 2, the thickness t and the width w are set to have the following rigidity values. The maximum thickness is 28 mm and the maximum width is 16 mm.

In the racket frame 2, a sheet of fiber reinforced prepreg made of carbon fibers is laminated on the surface of an internal pressure tube to form a reinforced fiber molding (layup) in advance, and this layup is placed in a molding die. After the mold is clamped, it is heated and molded under the conditions of 160 ° C. and 15 minutes. At that time, the internal pressure applied to the internal pressure tube is 88.2.
It is set to N / cm ² .

In a part of the head portion 3 and the throat portion 4 surrounding the ball striking face of the racket frame 2, a fiber reinforced prepreg in which the tensile elastic modulus of the reinforcing fibers is 35 t or more and 45 t or less is laminated together with other fiber reinforced prepregs. Further, a fiber reinforced prepreg in which the fiber angle of the reinforcing fibers is in the direction of 0 ° or more and 10 ° or less with respect to the length direction (axial direction) of the racket frame 2 is laminated with other fiber reinforced prepregs.

In this way, the racket frame 2 formed by laminating the prepregs has a ball striking surface rigidity (rigidity of the ball striking surface in the out-of-plane direction) value of 1607.2 N / cm, and a secondary peculiarity in the out-of-plane direction. Frequency (F1) is 520 Hz, lateral pressure rigidity (rigidity in the in-plane direction of the ball striking face) value (G2) is 793.8 N
/ Cm, the hitting surface rigidity value (G1) and the lateral pressure rigidity value (G
The ratio (G1 / G2) of 2) is 2.02.

The string is stretched at 50 lbs,
Absolute value | F1 of the difference from the secondary natural frequency (F1) in the out-of-plane direction with the natural frequency (F2) of the string set to 540 Hz
-F2 | is set to 20 Hz.

The numerical value MI obtained by multiplying the weight of the racket frame and the distance (balance) from the grip end to the position of the center of gravity is 89835 g · mm. Further, the moment of inertia (Is) in the swing direction of the racket frame is 490000 g · cm ² , the moment of inertia (Ic) in the center direction is 13900 g · cm ² , the moment of inertia (Is) in the swing direction and the moment of inertia (Ic) in the center direction. ) Ratio (Is / Ic) is 35.3. As described above, by setting each stiffness value, natural frequency, etc., a lightweight tennis racket having high resilience performance and excellent control performance is obtained.

Example 1 of the tennis racket of the present invention will be described below.
12 and Comparative Examples 1 and 2 will be described in detail.

All of the examples and comparative examples have the frame shape shown in FIG. 1, and the total length is 700 mm, the maximum frame thickness is 28 mm, and the maximum frame width is 16 mm. The hitting surface rigidity, lateral pressure rigidity, out-of-plane secondary natural frequency, string natural frequency, racket frame weight, balance, and inertia moment (swing direction, center direction) are set as shown in Table 1. The above-mentioned item values were measured by the methods described below.

Carbon fiber is manufactured by Mitsubishi Rayon Co., Ltd.
Made: HR40, TR50, Toho Rayon Co., Ltd .: IM
600, manufactured by Toray Industries, Inc .: T-700, T-800, M4
0M, M30G) (fiber angle 0 °, 10 °, 22 °, 3
0 °, 45 °, 90 °, tensile elastic modulus 200 GPa-50
0 GPa) and an epoxy resin was used as the thermosetting resin. A fiber reinforced prepreg made of carbon fiber / epoxy resin was laminated on a mandrel coated with a nylon tube, the mandrel was taken out and set in a mold, and then a racket frame was produced by heat and pressure molding. In each of the examples and comparative examples, fiber reinforced prepregs were laminated so that the values set in Table 1 were obtained.

[0051]

[Table 1]

(Examples 1 to 12) The racket frame weight was set to 280 g or less, the striking surface rigidity value (G1), the lateral pressure rigidity value (G2), the rigidity ratio (G1 / G2), and the out-of-plane secondary natural frequency. (F1) was set within the specified range. The other item values were set as shown in Table 1 above. The string tension was set between 35 lbs and 55 lbs.

(Comparative Example 1 and Comparative Example 2) Rigid surface rigidity value (G
1), lateral pressure rigidity value (G2), rigidity ratio (G1 / G2), and out-of-plane secondary natural frequency (F1) were all set outside the specified ranges. The other item values were set as shown in Table 1 above. The string tension was set to 50 lbs. The racket frame weight of Comparative Example 1 was 285 g.

With respect to the tennis rackets of Examples 1 to 12 and Comparative Examples 1 and 2, the coefficient of restitution was measured, and the actual hitting evaluation (flying, control, surface stability,
Operability). The results of each measurement and evaluation are shown in Table 1 above.

(Measurement of Rigidity of Ball Hitting Surface) As shown in FIG. 4, the tennis racket 1 is arranged horizontally and the top 3a of the head 3 of the tennis racket is received by a jig for receiving the ball hitting surface rigidity (rigidity in the out-of-plane direction). 61 (R15), and a jig 62 (R15) was provided at a position 340 mm away from the top 3a to receive the position of the yoke 7 from both sides of the throat portion 4. In this state, the pressing tool 63 (R1) is moved to a position 170 mm away from the receiving jig 61 in the direction of the receiving jig 62.
0), a load of 784 N was applied from above, the spring constant was calculated from the displacement under load, and the ball striking surface rigidity was measured.

(Measurement of Lateral Pressure Rigidity) As shown in FIG. 5, lateral pressure stiffness is measured by laterally striking the tennis racket 1 as shown in FIG.
The tennis racket 1 is held with the vertical direction as.
In this state, a load of 784N was applied to the side 3b of the upper head portion 3 by the flat plate P, the spring constant was calculated from the displacement at the time of load, and the lateral pressure rigidity was measured.

(Measurement of Out-of-Plane Secondary Natural Frequency) Tennis rackets of Examples and Comparative Examples in which only required accessory parts were attached to the racket frame were attached to the upper end of the head portion 3 as shown in FIG. 6 (A). The cord 51 was suspended, and the accelerometer 53 was fixed vertically to the frame surface at a continuous point between the throat portion 4 and the shaft portion 5. In this state, as shown in FIG. 6B, the impact hammer 55 vibrates the frame on the back side of the acceleration pickup meter 53. 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 out-of-plane secondary natural frequency of the tennis racket was obtained. The values measured for the tennis rackets of each example and comparative example are shown in Table 1 above.

(Measurement of Natural Frequency of String) As shown in FIG. 6 (C), the upper end of the head portion 3 is suspended by a string 51 while the string of the tennis racket is stretched, and the throat portion 4 and the shaft portion 5 are suspended. The accelerometer 53 was fixed vertically to the frame surface at the continuous points. In this state, the string was vibrated by the impact hammer 55 in the central portion of the head portion 3. Then, the string natural frequency was obtained by the same method as the out-of-plane secondary natural frequency. The values measured for the tennis rackets of each example and comparative example are shown in Table 1 above.

(Measurement of Moment of Inertia) As shown in FIG. 7A, required accessories are attached to the racket frame. The tennis racket 1 is suspended with a moment of inertia measuring device, with the grip of the tennis racket as the upper end,
The swing period Ts was measured, and the moment of inertia in the swing direction (the moment of inertia in the swing direction out of the ball striking surface with the grip end as a fulcrum) was calculated by the following formula.
As shown in FIG. 7 (B), the inertia moment measuring device suspends the tennis racket 1 with the grip as the upper end, measures the center period Tc, and calculates the moment of inertia in the center direction (the center axis of the grip portion by the following formula). The moment of inertia around) was calculated.

(Calculation of moment of inertia) Swing direction: Is [g · cm^Two] Is = M × g × h (Ts / 2 / π)^Two-Ic Center direction: Ic [g · cm^Two] Ic = 254458 × (Tc / π)^Two-8357 Center of gravity: Ig Ig = Is-m (1 + 2.6)^Two Here, M = m + mc, h = (m × l−mc × lc) /
m + 2.6, m: racket weight, l: racket bar
Lance point, mc: chuck weight, lc: chuck
It is a balance point.

(Measurement of Coefficient of Restitution) As shown in FIG. 8, the coefficient of restitution is that the tennis racket 1 of the example and the comparative example is stretched with a gut under tension of 60 pounds in length and 55 pounds in width, and each tennis racket is stretched. The grip is softly fixed so that it becomes free in the vertical state, and the tennis ball is 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 is measured. did. 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.

(Actual Hit Evaluation) A questionnaire survey was conducted on racket flight, control, surface stability, and operability. Scored with a maximum of 5 points (the higher the better), the average of the scoring results of 66 middle and advanced players (who have been playing tennis for 10 years or more and who still meet the conditions of playing more than 3 days a week) is taken.

As shown in Table 1, in each of Examples 1 to 12, the coefficient of restitution was higher than that in Comparative Examples 1 and 2, and the flight performance evaluation in the actual hit evaluation also showed good results. It was confirmed that the resilience performance was improved. It is considered that this is because the secondary natural frequency in the out-of-plane direction is close to the natural frequency of the string, so that energy loss is minimized (impedance matching). In Comparative Examples 1 and 2, the resilience performance is lowered because the natural frequencies of the two are separated.

Further, in Examples 1 to 12, since the striking surface has high rigidity (out-of-plane direction, in-plane direction), the surface stability contributing to control performance is evaluated well, and the higher the rigidity, the better the evaluation result. Was confirmed. On the other hand, Comparative Example 2 was poor in surface stability because of its low rigidity.

Further, in Examples 1 to 12, MI, which is a value obtained by multiplying the weight by the balance point, is 82000 g.
It is set in the range of mm to 92000 g · mm, and the operability that contributes to the control performance is evaluated well,
It was confirmed that the smaller the MI, the better the evaluation result. Comparative Example 1 is evaluated to have low operability because the MI value is large. It was confirmed that the evaluation of Examples 1 to 12 was also good in the evaluation of the control performance in which the surface stability and the operability were comprehensively evaluated.

[0066]

As is apparent from the above description, according to the present invention, energy loss is suppressed by bringing the natural frequency of the string close to the secondary natural frequency in the out-of-plane direction (impedance matching). It is possible to improve the resilience performance of the tennis racket. Further, the control performance can be improved by improving the rigidity value (out-of-plane direction, in-plane direction) of the ball striking surface, particularly the in-plane direction rigidity (lateral pressure rigidity) value and increasing the surface stability.

High resilience performance, excellent surface stability, controllability such as operability, etc., and light weight have realized that even women and seniors can obtain flying performance with less force and have good control. A tennis racket having performance can be provided.

[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 a side view of the tennis racket of the first embodiment of the present invention.

FIG. 3 is an AA of the head portion of the racket frame of FIG.
It is a line sectional view.

FIG. 4 is a schematic view showing a method for measuring the ball striking surface rigidity of the racket frame.

FIG. 5 is a schematic view showing a method for measuring lateral pressure rigidity of a racket frame.

6 (A), (B) and (C) are schematic diagrams showing a method of measuring the secondary natural frequency in the out-of-plane direction and the natural frequency of the string.

7A and 7B are schematic diagrams showing a method for measuring a moment of inertia of a racket frame.

FIG. 8 is a schematic diagram showing a method for measuring the coefficient of restitution of a racket frame.

[Explanation of symbols]

1 tennis racket 2 racket frames 3 head 4 throat section 5 Shaft 6 Grip part 7 York F ball striking surface

[Procedure amendment]

[Submission date] December 24, 2002 (2002.12.
24)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

[0009]

In order to solve the above problems, the present invention is, firstly, a tennis racket comprising a racket frame made of fiber reinforced resin, wherein the weight of the racket frame is 100 g or more and 280 g or less. , The rigidity value (G1) of the ball striking surface in the out-of-plane direction is 1568 N / cm or more 2
156 N / cm or less, rigidity value in the in-plane direction of the ball striking surface (G
2) is 784 N / cm or more and 1274 N / cm or less,
The ratio (G1 / G2) of (G1) and (G2) is 1.5 or more and 2.4 or less, and the moment of inertia (Is) in the swing direction of the racket frame is 440000 g.
cm ² or more and 520,000 g · cm ² or less, the inertial moment (Ic) in the center direction is 13500 g · cm ² or more and 17,000 g · cm ² or less, and the inertial moment (Is) in the swing direction and the inertial moment (Ic) in the center direction are We provide tennis rackets with a ratio (Is / Ic) of 28 or more and 36 or less.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Delete

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Delete

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Delete

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Delete

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Delete

[Procedure Amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Delete

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Delete

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

Secondly, the present invention is a tennis racket comprising a racket frame made of fiber reinforced resin, wherein the weight of the racket frame is 100 g or more and 280 g or less, and the secondary natural frequency in the out-of-plane direction of the ball striking face. (F1) 48
0 Hz or more and 600 Hz or less, and the rigidity value (G1) of the ball striking surface in the out-of-plane direction is 1568 N / cm or more and 2156 N
/ Cm or less, and the moment of inertia (Is) in the swing direction of the racket frame is 440000 g.
cm ² or more and 520,000 g · cm ² or less, the inertial moment (Ic) in the center direction is 13500 g · cm ² or more and 17,000 g · cm ² or less, and the inertial moment (Is) in the swing direction and the inertial moment (Ic) in the center direction are We provide tennis rackets with a ratio (Is / Ic) of 28 or more and 36 or less.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

The above-mentioned first and second tennis rackets are
It was made based on the results of experiments including the inventor's earnest research and trial hitting tests. To improve the controllability of a lightweight tennis racket, the hitting surface (out-of-plane direction,
Rigidity value in the in-plane direction, especially rigidity in the in-plane direction (side pressure rigidity)
It is based on the finding that increasing the value is effective in increasing the surface stability. The above tennis racket has a secondary natural frequency (F
Absolute value of the difference between 1) and the natural frequency (F2) of the string |
It is preferable that F1-F2 | is set to 0 Hz or more and 100 Hz or less.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

An absolute value | F1-F2 of the difference between the natural frequency (F2) of the string having the above-mentioned first and second tennis racket configurations and stretched on the ball striking face (F2) and (F1).
It is preferable that | is set to 0 Hz or more and 100 Hz or less. That is, the rigidity value (G1) of the ball striking surface in the out-of-plane direction is set to 1
568 N / cm or more and 2156 N / cm or less, the secondary natural frequency (F1) in the out-of-plane direction is 480 Hz or more and 600 Hz or less, and the rigidity value (G2) in the in-plane direction of the ball striking surface is 784 N / c.
m or more and 1274 N / cm or less, the above (G1) and (G2)
Ratio (G1 / G2) is in the range of 1.5 or more and 2.4 or less, and the absolute value of the difference between the natural frequency (F2) of the string stretched on the ball striking face and the above (F1) | F1-F2 | Is set to 0 Hz or more and 100 Hz or less.

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

As described above, in the tennis racket of the present invention, the inertia moment in the swing direction of the racket frame (the inertia moment in the swing direction outside the striking surface with the grip end as a fulcrum) (Is) is 440000 g · cm ^2.
The above is set to 520,000 g · cm ² or less. Preferably 460000 g · cm ² or more and 500000 g · c
m ² or less. This is Is 440000g
If it is less than cm ² , the racket frame is too light and the ball does not fly, and the Is is 520,000.
This is because if it is larger than g · cm ² , the racket frame is heavy and it is difficult to swing it out.

[Procedure Amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0066

[Correction method] Change

[Correction content]

[0066]

As is apparent from the above description, according to the present invention, the rigidity value of the ball striking surface (out-of-plane direction, in-plane direction), especially the in-plane rigidity (lateral pressure rigidity) value is improved, The control performance can be improved by increasing the surface stability.

Claims (4)

[Claims] 1. A tennis racket comprising a racket frame made of fiber reinforced resin, wherein the racket frame has a weight of 100 g or more and 280 g or less, and a rigidity value (G1) in the out-of-plane direction of the ball striking face is 1568.
N / cm or more and 2156 N / cm or less, and the rigidity value (G2) in the in-plane direction of the ball striking surface is 784 N / cm or more and 1274 N / c
m or less, and the ratio (G1 / G) of (G1) and (G2)
2) is 1.5 or more and 2.4 or less, and the moment of inertia (Is) in the swing direction of the racket frame is 4
40000 g · cm ² or more and 520,000 g · cm ² or less, and a moment of inertia (Ic) in the center direction is 1350
0 g · cm ² or more and 17000 g · cm ² or less, tennis rackets that the ratio of the swing direction of the moment of inertia (Is) and the center direction of the moment of inertia (Ic) and (Is / Ic) and 28 or more 36 or less. 2. A tennis racket comprising a racket frame made of fiber reinforced resin, wherein the weight of the racket frame is 100 g or more and 280 g or less, and the secondary natural frequency (F1) of the ball striking face in the out-of-plane direction is 480 Hz or more. 600 Hz or less, and the rigidity value (G1) of the ball striking face in the out-of-plane direction is 1568 N / cm or more and 215
6 N / cm or less, and the moment of inertia (Is) in the swing direction of the racket frame is 440000.
g · cm ² or more and 520000g · cm ² or less, center direction of the inertia moment (Ic) 13500g · cm
A tennis racket having a ratio of ² or more and 17,000 g · cm ² or less and a ratio (Is / Ic) of the inertial moment (Is) in the swing direction to the inertial moment (Ic) in the center direction of 28 or more and 36 or less. 3. The tensile modulus of the reinforcing fiber is 35t or more and 45t or less, and the fiber angle of the reinforcing fiber is the longitudinal direction (axial direction) of the racket frame in a part of the head portion and the throat portion surrounding the ball striking face of the racket frame. 0 degrees or more and 10 degrees or less, and / or the maximum thickness of the head part is 2
The tennis racket according to claim 1 or 2, wherein the maximum width is 6 mm to 30 mm and the maximum width is 13 mm to 16 mm. 4. The numerical value MI obtained by multiplying the weight of the racket frame by the distance (balance) from the grip end to the position of the center of gravity is 82000 g · mm or more and 92000 g · mm.
mm or less, any one of claims 1 to 3
Tennis racket described in paragraph.