JP2001252376A - Racket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a racket which is further reduced in weight or furthermore increased in the area of a face part and has excellent impact relieving property and repellence even when a ball is hit back, off the center of the racket. SOLUTION: The racket in which the face part 2 is formed in such a manner that the length of the warp of the gut spread in the face part 2 is longer in the warp in the positions apart to both right and left sides than the warp in a position corresponding to the position on a central axis 5A of the grip part 4. For example, the tennis racket 1 which can make the length of the warp on both sides thereof longer than the central warp is obtained by providing the inner periphery side of the face part 2 with grooves 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racket used for tennis, squash, badminton, etc.
The present invention relates to a racket in which a reduction in repulsion is minimized even when a ball is hit away from a sweet spot and a sweet area is further enlarged.

[0002]

2. Description of the Related Art The face portion of a racket generally has an elliptical shape, a substantially elliptical shape approximated to a square, an oval shape, and the like. A gut attached to the face portion has a central axis of a grip portion. The length of the warp at the center of the face surface corresponding to the top is the longest. Here, the present inventors have already disclosed JP-A-10-99472 from the viewpoint that it is effective to make the entire length of the warp of the gut equal to the length of the warp in the center of the face as much as possible in order to enlarge the sweet area. Discloses a racket in which a sweet area is enlarged.

That is, as shown in FIG.
No. 9472 discloses a groove 6 extending in the circumferential direction of the face portion 2 on the inner peripheral surface side of the face portion 2 of the tennis racket 1 and at the center in the thickness direction perpendicular to the face surface.
In a cross section cut parallel to the face surface at the center in the thickness direction as shown in FIG. 8, portions 7, 8, 9, and 10 with increased curvature are formed. Therefore, the lengths of the warp yarns on both sides thereof approach the length of the warp yarn at the center of the face portion 2, and the sweet area is enlarged.

As described above, the invention disclosed in Japanese Patent Application Laid-Open No. 10-99472 is very effective for expanding a sweet area. However, recent rackets, especially tennis rackets, have become increasingly lighter, and as a result, the impact when hitting the ball off center has increased, and the area has increased due to the expansion of the face surface, resulting in a decrease in surface stability. The new problem has emerged, and the tendency of the ball to repel when hitting the ball has been relatively noticeable.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention is a further improvement of the invention disclosed in Japanese Patent Application Laid-Open No. 10-99472, in which a lighter racket and a larger face area are provided. It is an object of the present invention to provide a racket having excellent impact relaxation and resilience even if a ball is hit off center.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the gist thereof is as follows. That is, a racket having at least a face portion and a grip portion, wherein the length of the warp of the gut stretched on the face portion is farther to the left and right than the warp at a position corresponding to the center axis of the grip portion. The present invention relates to a racket in which a face portion is formed such that the warp in the above is longer, and the above problem is solved by making the racket capable of making the warp on both sides longer than the length of the center warp. is there.

[0007] Preferably, the position where the length of the warp of the gut is the maximum is 20 degrees from the center axis of the grip portion.
By using a racket having a face portion formed so as to be separated from each other within a range of not less than 80 mm and not more than 80 mm, an effect of suppressing a decrease in repulsion can be surely realized.

A racket having at least a face portion and a grip portion, wherein the length of the weft thread of the gut stretched on the face portion is greater than the length of the weft thread at a position corresponding to the vertical center axis of the face portion. The present invention relates to a racket in which a face portion is formed such that a weft at a position separated from the upper and lower sides becomes longer, and in a case where an off-center hit occurs in a vertical direction of a face surface, a racket capable of suppressing a decrease in repulsive force. It is what it was.

[0009] The left and right warp yarns are made longer than the gut warp yarns stretched at the top center of the face portion.
By making the upper and lower weft yarns longer than the gut weft yarn stretched at the center of the side of the face portion, the sweet area can be expanded in both the left-right direction and the up-down direction of the face surface.

Here, as described above, the gut warp and / or
Alternatively, in order to lengthen the weft, a groove extending in the circumferential direction of the face portion is provided at the center portion in the thickness direction perpendicular to the face surface on the inner circumferential surface side of the face portion, and the groove allows the inner circumferential surface of the face portion to be interposed. The length of the gut should be longer than the opening width. In addition, right and left 10m from the center axis of the grip
If the groove is not provided on the inner peripheral surface side of the face part within the range of m, the decrease in the strength of the face part can be minimized compared to the case where the groove is also provided in that area. In addition, since the presence of the groove can be noticed by the player, the psychological effect of expanding the sweet area can be expected.
When the strength of the face portion is insufficient due to the provision of the groove, a reinforcing member may be added to the face portion in the range where the groove is provided.

Further, the maximum opening width in the vertical direction between the inner peripheral surfaces of the face portion is W1, and the maximum opening width in the horizontal direction is W2.
, The aperture ratio, W1 / W2, is 1.38 to 1.
It is preferable to form the face portion vertically long so as to be within the range of 52 because a decrease in repulsion can be suppressed within a range where the racket does not feel strange.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1, a racket according to the present invention has a face portion 2 having a substantially elliptical shape (a shape in which the ellipse is slightly closer to a square) as shown in FIG.
And a tennis racket 1 comprising a shaft portion 3 that forms a substantially triangular shape with the face portion below the face portion 2 and a grip portion 4 at the base of the shaft portion 3. Here, the face portion 2, the shaft portion 3, and the grip portion 4 are integrally formed of carbon fiber reinforced resin. The material of the racket is not limited to carbon fiber reinforced resin, but wood, a metal having a relatively small specific gravity such as a titanium alloy or duralumin, an organic fiber, a fiber reinforced resin obtained by impregnating a sheet of glass fiber with a resin, or the like is used. be able to.

The face 2, shaft 3 and grip 4 which are integrally formed are hollow inside (FIG. 2 shows a hollow cross section of the face 2) to reduce the weight. I have. That is, the tennis racket 1 shown in FIG. 1 has a racket weight of 260 g before being gutted. It should be noted that the inside of the face portion and the like can be improved in strength by filling it with a foam material without leaving it hollow. The preferred racket weight range for the tennis racket is 220 to 320 g, more preferably 2 to 320 g.
30 to 270 g. If it is lighter than 220 g, it is difficult to secure the necessary strength, and if it is heavier than 320 g, the weight is remarkably felt, and the impact when hitting the ball off center and the stability of the face surface are reduced. This is because they will leave.

The face portion 2 is formed such that, when the gut is stretched, the warp yarn at a position away from the left and right sides is longer than the warp yarn of the gut at a position corresponding to the center axis 5A of the grip portion. I have. Specifically, FIG.
As shown in FIG. 2B, the thickness direction perpendicular to the face surface is on the inner peripheral surface side of the face portion 2 on both sides of the face section on the central axis 5A of the grip portion shown in FIG. Depth 3.0 extending in the circumferential direction of the face portion at the center of
By providing the groove 6 of mm, the warp length of the gut at a position separated to the left and right is increased.

Therefore, in a cross section cut parallel to the face surface at the center in the thickness direction of the face portion as shown in FIG. 3, the warp length L1 of the gut at the position corresponding to the center axis 5A of the grip portion is more left and right. The warp length L2 at the position distant to both sides is longer, so that even when the ball is hit off center, the decrease in repulsion is suppressed, and the same repulsion as when the ball is caught at the sweet spot position is obtained. You can get it. The gut warp at a position corresponding to the center axis 5A of the grip portion indicates the warp when the center axis 5A of the grip portion overlaps the warp yarn, and when the warp yarn does not overlap the center axis 5A of the grip portion. FIG. 3 shows two warps L1 and L1 on both sides.

Further, in FIG. 3, four grooves 6 extending in the circumferential direction of the face portion 2 are provided at four positions, and only the warp is set to L1 <L2. At the same time, the same applies to the weft. That is, the face portion 2 is formed such that the weft yarn length L4 at a position distant to the upper and lower sides is longer than the weft yarn length L3 at a position corresponding to the vertical center axis 5B of the face portion. Specifically, similarly to the case of the warp yarn described above, a plurality of grooves extending in the circumferential direction of the face portion 2 may be provided vertically symmetrically with respect to the center axis 5B in the vertical direction of the face portion. In this way, even if an off-center hit is made in the vertical direction of the face, a decrease in repulsion is suppressed,
The same repulsive force as when the ball is captured at the sweet spot position can be obtained. Even if grooves are provided only on the left and right sides of the top of the face portion 2 and only the warp yarns are longest on both sides, grooves are provided only on the center and upper and lower sides of the face portion 2 and only the weft yarns are longest vertically. It goes without saying that it is possible to do so.

Further, it has been experimentally confirmed that the repulsive force of the ball is remarkably reduced when the ball is caught at a position 20 mm or more left and right from the center axis 5A of the grip portion. Accordingly, the length of the warp of the gut stretched on the face surface is set to 20 m on the left and right with respect to the central axis 5A of the grip portion.
It is more effective for the player to realize the effect of suppressing the reduction of the repulsive force most effectively when the distance is at least m or more away. Therefore, in the tennis racket 1 shown in FIG. 3, no groove is provided on the inner peripheral surface side of the face portion 2 within a range of 25 mm left and right (50 mm between the positions A and A) from the center axis 5A of the grip portion. On the other hand, at a position 62.5 mm apart from the left and right (positions B, B, interval 125 mm), the groove 6 is provided so that the warp length L2 of the gut becomes maximum.

It is to be noted that the reason why the groove is not provided within a predetermined range on the left and right from the center axis 5A of the grip portion is that the player recognizes the existence of the left and right grooves 6, can visually imagine the effect, and stimulates the purchase will. It also aims at psychological effects such as. Therefore, in order to achieve these effects sufficiently, at least 10 right and left sides from the center axis 5A of the grip portion are required.
It is preferable that no groove be provided within mm.

On the other hand, the provision of the groove 6 in the face portion 2 may cause the strength of the portion to be insufficient. in this case,
As shown in FIG. 2B, the reinforcing member 11 may be added to the face portion 2 in the area where the groove 6 is provided. Here, as the reinforcing member 11, a plurality of unidirectional carbon fiber reinforced resins (UD prepreg) having a modulus of elasticity of 25 tons, and a total of eight unidirectional carbon fiber reinforced resins wound in a string shape in the longitudinal direction are used. However, besides this, wires such as carbon fibers, glass fibers, organic fibers, and ceramic fibers and woven fabrics, wires such as aluminum, stainless steel, titanium, copper, and tungsten can also be used, and the number of wires used is also appropriately determined. . Further, the reinforcing member may be provided not only in the area where the groove 6 is provided but also around the entire circumference of the face portion 2.

By the way, the schematic shape of the face portion of the tennis racket is such that when the maximum opening width in the vertical direction of the face portion is W1 and the maximum opening width in the left-right direction is W2,
The aperture ratio is given by W1 / W2. The tennis racket 1 shown in FIG. 1 has a vertically long face surface in which W1 / W2 = 1.4, but this is achieved by making the face portion 2 vertically long so that the warp of the gut is lengthened and rebounded. It is to raise power.

The opening ratio W1 / W2 is 1.38 to 1.5.
It is preferably within the range of 2. W1 / W2 <1.3
When the ratio is 8, the face becomes almost circular and it becomes difficult to make the warp of the gut sufficiently long.
If 2> 1.52, the face portion becomes too long, and it becomes difficult to increase the warp length at a position farther to the left and right sides than the warp length at a position corresponding to the center axis of the grip portion. is there.

Further, by setting W1 / W2 in the range of 1.38 to 1.52 and making the side of the face portion straighter than a general tennis racket, the hoop of the face portion can be made effective. Here, the hoop means that at the time of hitting the ball, the face portion bends and deforms so as to raise the rebound of the ball simultaneously with the deformation of the gut. Therefore, an improvement in resilience and a mild feel at impact can be obtained within a range in which the racket shape does not cause discomfort.

The specific dimensions of the tennis racket 1 shown in FIG. 1 are the maximum opening width W1 of the face portion 2 in the vertical direction.
Is 350 mm, which is in the range of 320 to 360 mm. This is because if it is smaller than 320 mm, it will not be possible to obtain a sufficient repulsive force at the time of an off-center hit, and if it is larger than 360 mm, the appearance will be poor, and the weight of the racket will increase due to the gut and the like. Because it becomes difficult to swing.

Both sides of the face portion 2 of the tennis racket 1 shown in FIG. 1 are formed by large curves having a radius of 450 mm. That is, by making both sides of the face portion 2 linear, the length of the weft yarn of the gut can be made nearly uniform over the entire face surface, and at the same time, due to the constraint of W1 / W2 = 1.4, the face portion passes through the inflection point. Since the top of 2 is also linear, the warp length of the gut can be made uniform overall. Therefore, even if the groove 6 is relatively shallow, the central axis 5A of the grip portion
The warp at a position farther to the left and right than the warp at a position corresponding to the upper side can be made longer.

The radius of both sides of the face portion is 30
0 mm or more and 700 mm or less, preferably 350 mm or more and 650 mm or less. If it is smaller than 300 mm, the face part will be close to a circle, and if you do not make the groove considerably deep,
This is because it is not possible to lengthen the warp at a position away from the center axis of the grip portion to the left and right sides. On the other hand, 700m
If it is larger than m, the face portion becomes too close to a square, and the shape is considerably different from the existing racket, so that there is considerable discomfort and the feeling of use is inferior.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The tennis racket 1 of FIG. 1 as described above is gutted to provide an embodiment, and the same tennis racket is provided as a comparative example except that the groove 6 is not provided.
Shown in Then, the ends of both grip portions are fixed, and a tennis ball launching machine is used to launch the racket toward the face of the racket, and the ball is hit from the center (the intersection of the center axes 5A and 5B in FIG. 1) with the center axis 5B. Was gradually released toward the right side, and the ball speed after rebound was measured relative to the ball speed before rebound (constant at a ball initial speed of 90 km / h).

FIG. 5 shows the repulsion coefficient (ball velocity after repulsion / ball initial velocity) obtained from the measured ball velocity after rebound. FIG. 6 shows the off-center distance on the horizontal axis and the restitution coefficient on the vertical axis. It is graphed as As is clear from FIG. 6, the racket of the present invention has a low repulsion force even when an off-center hit occurs. In particular, within a range of 20 mm from the center where the hit point is most frequently hit, the restitution coefficient is significantly larger than that of the comparative example. It has increased. In addition, as a result of the test hit evaluation, it was possible to obtain an evaluation that the hit feeling was soft even when the example was off center.

[0028]

As described above, the racket of the present invention has a low repulsion force even when an off-center hit is made, and has a soft feel. That is, the sweet area can be expanded even in a racket whose weight is further reduced or a racket whose face area is further increased, and a racket having excellent impact relaxation and resilience can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view showing an example in which the present invention is applied to a tennis racket.

2 is a cross-sectional view showing a cross-sectional shape of a grooveless portion and a grooved portion of a face portion in the tennis racket of FIG. 1;

FIG. 3 is a partial cross-sectional view of the tennis racket of FIG. 1 cut at a center in the thickness direction of the face portion in parallel with the face surface.

FIG. 4 is a diagram illustrating specifications of tennis rackets according to an example and a comparative example.

FIG. 5 is a diagram illustrating a ball speed and a resilience coefficient after rebound when balls are launched toward the face surfaces of the tennis rackets of the example and the comparative example.

FIG. 6 is a diagram illustrating a relationship between an off-center distance and a coefficient of restitution.

FIG. 7 is a front view showing a tennis racket previously applied by the present applicant.

FIG. 8 is a partial cross-sectional view of the tennis racket of FIG. 7 cut at the center in the thickness direction of the face portion in parallel with the face surface.

[Explanation of symbols]

1 Tennis Racket 2 Face 3 Shaft 4 Grip 5A, 5B Center Shaft 6 Groove 7, 8, 9, 10 Large Curvature 11 Reinforcement Member L1, L2 Warp Length of Gut L3, L4 横 Weft length of gut W1 最大 Maximum opening width in the vertical direction between inner peripheral surfaces of face portion W2 最大 Maximum opening width in the horizontal direction between inner peripheral surfaces of face portion

Claims (7)

[Claims] 1. A racket having at least a face portion and a grip portion, wherein the length of the warp thread of the gut stretched on the face portion is on the left and right sides of the warp thread at a position corresponding to the center axis of the grip portion. A racket characterized in that a face portion is formed so that a warp at a distant position becomes longer. 2. The position where the length of the warp yarn of the gut becomes maximum is 20 mm or more and 80 m or more from the center axis of the grip portion.
The racket according to claim 1, wherein the face portion is formed so as to be located at a distance within a range of m or less. 3. A racket having at least a face portion and a grip portion, wherein the length of the weft thread of the gut stretched on the face portion is greater than the length of the weft thread at a position corresponding to the vertical axis of the face portion. A racket characterized in that a face portion is formed so that a weft at a position separated from the upper and lower sides becomes longer. 4. A groove extending in the circumferential direction of the face portion is provided on the inner circumferential surface side of the face portion and at a central portion in a thickness direction perpendicular to the face surface, and the groove extends between the inner circumferential surfaces of the face portion. 4. The racket according to claim 1, wherein the length of the gut is longer than the opening width. 5. Right and left 10 mm from the center axis of the grip portion
The racket according to claim 4, wherein no groove is provided on the inner peripheral surface side of the face portion in a range within. 6. The racket according to claim 4, wherein a reinforcing member is added to the face portion in an area where the groove is provided. 7. When the maximum opening width in the vertical direction between the inner peripheral surfaces of the face portion is W1 and the maximum opening width in the horizontal direction is W2, the opening ratio, W1 / W2, is 1.38 to 1.52.
The racket according to any one of claims 1 to 6, wherein the face portion is formed so as to fall within the range of (1).