JP2002035171A - Racket frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a racket frame which achieves a higher restitution characteristic and a surface stability at hitting without degrading appearance. SOLUTION: A mesh sheet 10 comprising metallic material with the specific gravity of 8.0 or more and furthermore, the tensile elongation percentage of 45% or more is wound covering the area from a part on the side of the inner circumference portion 1 of a ball hitting part to the side of the outer circumference portion 16 thereof except for the area R at the central part, where the gut 2 is inserted, on the side of the inner circumference portion 15 thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racket frame (hereinafter, referred to as a racket frame) used in tennis, badminton, squash, and the like, and more particularly to a racket frame molded from a fiber-reinforced resin. is there.

[0002]

2. Description of the Related Art Usually, a racket frame 31 of this kind is used.
Is, for example, as shown in FIGS.
2, a shaft portion 33, and a grip portion 34 have a tubular structure composed of an outer shell layer 35 made of fiber reinforced resin, and the hitting portion 3 of the racket frame 31
2 has a large number of gut insertion holes 38 penetrating the outer peripheral side surface 36 and the inner peripheral side surface 37. A gut protection groove 39 is recessed on the outer peripheral side surface 36 of the hitting portion 32 and the gut protection groove 39 is formed.
In each of the gut insertion holes 38, a gut protection groove 39, and a gut protection member 40 having a base portion and a tube portion fitted into the gut insertion hole 38 are mounted. A gut 41 made of a material such as nylon, sheep, and whale muscle is inserted to form a gut net surface.

By the way, a racket frame 31 has been conventionally used.
As shown in FIG. 10, the maximum width W position of the hitting portion 32 in the direction orthogonal to the longitudinal axis y of the racket frame 31 in order to improve the resilience characteristics and surface stability (controllability) when hitting the ball. Region, that is, both side portions 42a sandwiching the sweet spot of the hitting portion 32 having an oval shape,
42b (when the hitting portion 32 is projected from the front, the hitting portion 3
For example, when the top portion 43 of 2 is set to 12:00, a mass body such as a lead plate is attached to a region corresponding to 9 o'clock and 3 o'clock, or the second moment of area of the portion is designed to be large. Means has been taken to increase the moment of inertia about the longitudinal axis y to improve the resilience characteristics and surface stability of the ball when hit with a sweet spot.

However, when a mass body such as a lead plate is attached to the racket frame 31 as described above, the racket frame is formed by the impact at the time of hitting the ball due to the difference in the elongation between the racket frame made of fiber reinforced resin and the mass body. When the frame is bent, the mass body cannot follow the frame, so that there is a problem that the adhesion between the two is reduced in time, the integrity is lost, and the mass body is easily peeled off. Was. In the case where the second moment of area of the frame is partially enlarged, the reinforcing fibers constituting the racket frame easily meander in this portion, so that stress concentration occurs at the time of impact and the strength becomes insufficient. There was a tendency.

[0005] Therefore, in recent years, as a configuration for solving such a problem and efficiently attaching a weight member to a racket frame, for example, Japanese Patent Application Laid-Open No. H11-290 is disclosed.
In No. 484, as shown in FIG. 12, the specific gravity is 4.53 and the elongation is 23 over the entire circumference of the surface of both sides 52a and 52b sandwiching the sweet spot of the racket frame 51.
It has been proposed and proposed to integrally attach a mesh piece 53 made of about% of pure titanium.

[0006]

In this type of proposal, the excellent toughness of pure titanium reduces the amount of flexure of the frame portion to improve the stability of the surface, and the pure titanium is used as the mesh piece 53. Therefore, even if it is attached in a slender shape along the longitudinal direction of the frame, the mesh piece 53 has a large elongation rate, so that it can sufficiently follow the bending of the frame.

However, since the specific gravity of the pure titanium itself constituting the mesh piece 53 is small (the mass per unit area is small), when the weight mass required for the racket frame 51 is to be obtained, the mesh is required. The piece 53 must be formed large. That is, as shown in FIG. 13, the mounting range of the mesh piece 53 is changed along both sides 52 of the frame along the circumferential direction of the frame.
a, 52b, the top part 54 side direction and the grip part 55
There was a problem that it had to be extended and expanded in the lateral direction. However, if the mesh pieces 53 are attached over a wide range of the frame in this way, the weight mass is dispersed, not only can the weight not be efficiently added, but also adversely affect the balance design of the racket frame, As a result, there is a problem that the swing-out property is deteriorated due to an increase in inertia.

Therefore, in order to solve such a problem, it is necessary to form a thick wall of the mesh piece 53 itself and take measures to design a large mass per unit area. Since the elongation rate of the mesh piece 53 is significantly reduced with the increase in the wall thickness,
The mesh piece 53 cannot follow the bending of the frame,
There has been a problem that the mesh piece 53 is peeled off from the racket frame 51 main body due to repeated use.

Further, as a result of analyzing the vibration mode characteristics of the racket frame 51, the present inventors have found that the weight (mesh piece 53) sandwiches the sweet spot between the racket frame 51 and the conventional racket frame 51. In the case where the weights (mesh pieces 53) are arranged on both side portions 52a and 52b of the frame, as shown in FIG. 12, the weights (mesh pieces 53) are separated from a region corresponding to the node 56 of the out-of-plane primary bending vibration M of the racket frame 51. Because it is located, the vibration occurring at the time of impact is likely to be amplified, the energy at the time of impact is consumed by this amplified vibration, and it is difficult to obtain good repulsion characteristics and surface stability at the time of impact. It turned out to be. That is, in order to obtain good resilience characteristics and surface stability at the time of impact, the racket frame 5 described above is used.
It has been found that it is advisable to concentrate the mass near the region corresponding to the node 56 of the out-of-plane primary bending vibration M of No. 1.

However, the area corresponding to the node 56 of the out-of-plane primary bending vibration M of the racket frame 51 is smaller than the area of both sides 52a and 52b of the frame.
As shown in FIG. 14, the mesh piece 53 having a small tensile elongation as described above has a structure in which both the outer peripheral side surface 57 and the inner peripheral side surface 58 have a small radius of curvature r.
Is wound, the mesh pieces 53 do not follow the curvature of the frame, so that a wrinkle 59 is easily generated. In particular, in the racket frame 51 described above, as shown in FIGS. 15 and 16, the mesh piece 53 is wound around the entire circumference of the cross section of the frame. Due to the difference between the curvature and the curvature, the mesh piece 53 is formed by
Has the disadvantage that the wrinkles 59 are generated by being compressed on the side, and as a result, stress is concentrated on the portion at the time of hitting, the strength of the frame is reduced, and the appearance is deteriorated. It had the following.

In view of the above problems, the present invention has been developed to provide a racket frame capable of obtaining good rebound characteristics and surface stability at the time of hitting without lowering the strength and appearance required as a racket frame. It is intended to provide.

[0012]

In order to achieve the above object, the present invention has the following arrangement. That is, claim 1 of the present invention relates to a racket frame composed of a fiber reinforced resin outer shell layer having a plurality of gut insertion holes penetrating the inner and outer peripheral side surfaces of the hitting portion, wherein at least the inner periphery of the hitting portion is provided. Except for the central region on the side surface, and on the surface in the region of the frame cross section from the inner peripheral side to the outer peripheral side, a mesh made of a metal material having a specific gravity of 8.0 or more and a tensile elongation of 45% or more A racket frame in which a seat is provided integrally.

According to a second aspect of the present invention, in the racket frame according to the first aspect, a concave groove is provided on an inner peripheral side surface of the hitting portion, and the mesh-like sheet covers the concave groove region. It is characterized by being arranged in the region of the frame cross section excluding.

A third aspect of the present invention is the racket frame according to the first or second aspect, wherein the mesh-like sheet comprises:
It is arranged in the range of 50% to 80% of the entire circumference of the frame section.

A fourth aspect of the present invention is the racket frame according to the first, second or third aspect, wherein the mesh-like sheet is a copper mesh.

Claim 5 is the above-mentioned claim 1, 2, 3, or
4. The racket frame according to item 4, wherein the mesh sheet is disposed in a region corresponding to a range of 0.7L to 0.9L of a total length L of the racket frame from an end portion of the grip portion. It is.

According to a sixth aspect of the present invention, in the racket frame according to the first, second, third, fourth or fifth aspect, the total mass of the mesh sheet disposed on the racket frame is the racket frame before the gut stretching. 0.3% to 1.
It is characterized in that it is set within the range of 0%.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to preferred embodiments described in detail with reference to the drawings. FIG. 1 is an external view showing a front surface and a side surface of a racket frame of the present embodiment. FIG. 2 is a cross-sectional view taken along line AA of FIG. 1, and FIG. The principal part reference explanatory drawing of a line part area | region is shown.

That is, the racket frame 1 of this embodiment is
As shown in FIG. 1, a gut 2 is stretched to form a gut net surface, and a left and right shaft portions 5 connecting the hitting portion 3 and the grip portion 4 are fiber-reinforced. It has a tubular structure integrally formed of resin. Figure 1
As shown in the figure, the out-of-plane primary bending vibration M generated when the racket frame 1 hits a ball is
Near the top portion 6 (within the range of 0.83L to 0.92L of the entire racket frame L from the end portion 7 of the grip portion 4) and near the grip portion 4 side (the end portion 7 of the grip portion 4).
More racket frame total length L 0.17L-0.30L
), The nodes 8a, 8b, and the antinode 9 of the vibration
It is in the region between the nodes 8a and 8b. In this embodiment, in the vicinity of the region of the vibration node 8a located on the side of the top portion 6 (when the top portion 6 of the hitting portion 3 is 12:00 when the hitting portion 3 is projected from the front, 10:00 and 20:00) (A region corresponding to time), a mesh sheet 10 made of a metal material as described later is integrally provided.

That is, the mesh sheet 10 has a number of holes formed in a thin sheet made of a heavy and soft metal material having a specific gravity of 8.0 or more and a tensile elongation of 45% or more. As shown in FIG. 4A, a plurality of slits 12 are provided in a thin sheet 11 as shown in FIG.
As shown in FIG. 2B, the sheet is formed of a so-called "expanded metal" sheet which is stretched to form a large number of openings 13. In the present embodiment, such a mesh sheet 10 is formed as shown in FIGS.
When integrally wound around the outer shell layer 14 made of fiber reinforced resin constituting the hitting portion 3, the mesh sheet 1
Numeral 0 denotes a part which is not wound around the entire circumference of the frame cross section, except for a region R of a central portion where the gut 2 on the inner peripheral side surface 15 side of the hitting portion 3 is inserted, and a part on the inner peripheral side surface 15 side. And is wound around the region from to the outer peripheral side surface 16 side.

Therefore, in the racket frame 1 of the present embodiment, it is possible to locally add a required mass to the racket frame 1 by using the mesh sheet 10 having a high specific gravity as described above. Further, since the mesh sheet 10 is disposed in the vicinity of the node 8a of the out-of-plane primary bending vibration M of the racket frame 1, the vibration generated at the time of impact does not need to be amplified and good repulsion is achieved. Characteristics and surface stability can be obtained. Further, since the mesh sheet 10 has a remarkably large tensile elongation as compared with the conventional pure titanium or the like, the mesh sheet 10 can sufficiently follow the bending of the frame at the time of impact, and the mesh sheet 10 , A region R of a central portion on the inner peripheral side surface 15 side of the hitting portion 3
Is formed so as to be wound around the area excluding the above, so that it is difficult for the strain stress generated due to the difference between the outer peripheral curvature and the inner peripheral curvature of the hitting portion 3 to act, and no wrinkles are generated.

The racket frame 1 of this embodiment as described above
For example, a plurality of prepreg sheets 18 for racket frame molding are laminated around a tube 17 for internal pressure molding to form a frame molded body 19, and this is formed into a cavity having a mold frame shape. In a normal manufacturing method of a racket frame made of fiber reinforced resin, in which compressed air or the like is injected into the tube 17 and then heated, as shown in FIG. The mesh sheet 10 cut to a length of about 80% is formed in a substantially C-shape on the outer periphery of the frame molded body 19 in a state before the hardening molding (the central part of the inner peripheral side surface 15 side of the hitting portion 3 is formed). After covering the region R (the region excluding the region R), a measure is taken such that the resin is integrally molded with a mold.

As the main reinforcing fibers constituting the racket frame 1 made of the fiber reinforced resin of the present embodiment, various types such as carbon fiber, glass fiber, boron fiber and aromatic polyamide fiber can be used. Carbon fibers are also preferable in terms of rigidity, mass and cost. As the matrix resin, an epoxy resin, a nylon resin or the like can be used, but an epoxy resin is preferable in view of strength and durability.

The material constituting the mesh sheet 10 is preferably a heavy, soft metal material having a specific gravity of 8.0 or more and a tensile elongation of 45% or more. As an example of a material that satisfies such characteristics, for example, a mesh sheet made of copper, lead, gold, silver, or the like can be given.

The shape, dimensions and mass of the mesh-like sheet 10 vary depending on the shape and mass of the racket frame 1 itself, vibration characteristics, and the like, but other factors such as the strength and operability of the racket frame 1 itself are also included. As a result of conducting many experiments in consideration of the above, it is preferable that the wall thickness is designed in the range of 50 μm to 100 μm. If the thickness is smaller than 50 μm, the mass per unit area becomes too small, and it becomes difficult to obtain good resilience characteristics and surface stability.
When the thickness is larger than 100 μm, the section modulus increases and the flexibility is lost, so that it is difficult to follow the frame. It is preferable that the mass of the mesh sheet 10 is set in the range of 0.3% to 1.0% of the mass of the racket frame 1 before the gut 2 is stretched. When the mass is smaller than 0.3%, good resilience characteristics and surface stability are hardly obtained, and when the mass is larger than 1.0%, operability of the racket frame deteriorates, which is preferable. Absent.

Further, the mesh-shaped sheet 10 is provided in an area other than the central area R on the inner peripheral side surface 15 side of the hitting portion 3, specifically, 50% to 80% of the entire cross-sectional length of the frame.
% Is preferably wound. When the mesh sheet 10 is wound in a range smaller than 50% of the entire circumference of the frame cross section, the mass per unit area that can be added to the racket frame 1 becomes too small, and the resilience characteristics and the surface stability. Cannot be satisfied. Further, when the mesh sheet 10 is wound in a range larger than 80% of the entire perimeter of the frame cross section, the mesh sheet 10 is liable to be wrinkled on the inner peripheral side surface 15 side of the hitting portion 3. . In this embodiment, when the mesh sheet is wound, the mesh sheet is wound in a range of 50% to 80% of the entire circumference of the frame with one mesh sheet. May be divided into two or more in the circumferential direction of the cross section of the frame and wound.

Hereinafter, the structure of another embodiment of the present invention will be described. That is, the racket frame 21 of the present embodiment is
Similarly to the configuration of the racket frame 1 described above, the region where the node of the out-of-plane primary bending vibration M generated when the racket frame 21 hits the ball (the top portion 6 of the hitting portion 3 when the hitting portion is projected from the front). When the time is set to 12:00, the mesh sheet 10 as described above is integrally disposed in the area corresponding to 10:00 and 2 o'clock).

The racket frame 21 of the present embodiment
6 and 7, a concave groove 22 is provided on the inner peripheral side surface 15 side of the hitting ball portion 3, and the mesh sheet 10 excludes the concave groove 22 region. It has a configuration arranged over the area of the frame cross section.

The racket frame 2 of the present embodiment as described above
In No. 1, the effective chord length of the gut 2 can be increased by forming the concave groove 22 on the inner peripheral side surface 15 side of the hitting portion 3, so that the sweet spot surface can be enlarged. Become. Also, by providing the concave groove 22, the shape of the inner peripheral side surface 15 of the hitting portion 3 is configured to be complicated.
Since the mesh-like sheet 10 is disposed in a region other than the concave groove 22, there is no problem that a wrinkle is generated.

[0030]

EXAMPLES In order to confirm the effects of the present invention, racket frames of the following Example 1 and Comparative Examples 1 to 4 were prepared.

That is, the racket frame 21 prepared as the first embodiment has a form in which a concave groove 22 is provided on the inner peripheral side surface 15 side of the hitting portion 3 as shown in FIGS. The area where the node 8a of the out-of-plane primary bending vibration M that occurs when the frame 21 hits the ball (when the hitting part 3 is projected from the front and the top part 6 of the hitting part 3 is 12:00 and 10:00 Two areas corresponding to two o'clock)
A sheet having a specific gravity of 8.9 and a mesh sheet 10 made of copper having a tensile elongation of 45% was provided integrally in a region of the frame cross section excluding the concave groove 22. The length of the mesh sheet 10 is 50 mm
The thickness was 100 μm, and the mass of each was 2 g.

As a comparative example 1, as shown in FIG. 8, a racket frame having a structure in which the mesh sheet 10 of the example 1 was wound around the entire cross section of the frame was prepared. Further, as Comparative Example 2, the mesh-shaped sheet 10 of Example 1 was formed on both sides 23a and 23b of the hitting portion 3 (when the hitting portion 3 was projected from the front, the top portion 6 of the hitting portion 3 was set at 12:00. , Two zones corresponding to 9 o'clock and 3 o'clock). Further, as Comparative Example 3, a racket in which a mesh sheet made of pure titanium having a specific gravity of 4.5 and a tensile elongation of 23% was integrally wound instead of the mesh sheet 10 of Example 1 I prepared a frame. The other configuration of Comparative Example 3 was the same as that of Example 1. Comparative Example 4 was the same as that of Comparative Example 3 except that the mesh sheet made of pure titanium used in Comparative Example 3 was formed to have a length of 200 mm so as to obtain the same mass as the mesh sheet 10 of Example 1. 3 was prepared.

The following tests were conducted on the racket frames of Example 1 and Comparative Examples 1 to 4 in order to confirm the rebound characteristics at the time of hitting. That is, as shown in FIG. 9, the ball 24 collides with the hitting portion 3 at a speed (Vo) of 28 m / sec in a state where the grip portion 4 of the racket frame having a gut stretched on the hitting portion 3 is held and fixed. The repulsion coefficient was determined from the ratio (Vr / Vo) of the speed (Vr) of the rebounded ball 24 to the speed of the incident ball 24, and was used as an index of the rebound characteristics. The greater the value of the coefficient of restitution, the better the resilience characteristics can be obtained. The measurement results at this time are shown in Table 1 below.

[0034]

[Table 1]

Further, in addition to the above test, actual hitting tests were performed on these racket frames. In this actual hit test, the ball 24 was actually hit with a racket frame of Example 1 and Comparative Examples 1 to 4 for a general amateur player, and the player felt the surface stability at the time of the hit. (Controllability) and evaluation of discomfort and appearance during play were evaluated. The test results at this time are shown in Table 2 below.

[0036]

[Table 2]

From these test results, the racket frame 1 of the first embodiment can ensure good appearance without curling wrinkles of the mesh sheet 10 as compared with the racket frames of Comparative Examples 1 to 4. It was confirmed that the racket frame had good rebound characteristics and surface stability when hit.

[0038]

As described above, since the mesh sheet used in the present invention is made of a very heavy metal material having a specific gravity of 8.0 or more, the mesh sheet does not need to have a large mounting area. A large mass can be locally added to the racket frame. Therefore, without significantly affecting the operability of the racket frame,
It is possible to improve the resilience characteristics and surface stability at the time of impact. In particular, when the mesh sheet is arranged in the vicinity of the node of the out-of-plane primary bending vibration of the racket frame, the resilience characteristics at the time of impact can be further improved.

At the same time, since the tensile elongation of the metal material constituting the mesh sheet is as soft as 45% or more, it is excellent in following the racket frame shape. Since the sheet is not wound around the entire circumference of the cross section of the racket frame, but is wound around a region excluding the region of the central portion on the inner peripheral side surface of the hitting portion, as in the related art There is no problem that the mesh-like sheet causes a wrinkle on the inner peripheral side surface of the hitting portion due to a strain stress caused by a difference between the outer peripheral curvature and the inner peripheral curvature of the hitting portion. Is obtained.

[Brief description of the drawings]

FIG. 1 is an external view illustrating the front and side surfaces of a racket frame according to an embodiment.

FIG. 2 is an end view taken along the line AA of FIG. 1;

FIG. 3 is a reference explanatory view of a main part of an area AA of FIG. 1;

FIG. 4 is an explanatory view showing a mesh sheet of the present embodiment.

FIG. 5 is an explanatory view illustrating a method of manufacturing the racket frame according to the embodiment.

FIG. 6 is an explanatory diagram showing another embodiment.

FIG. 7 is an explanatory diagram showing another embodiment.

FIG. 8 is an explanatory diagram illustrating a comparative example.

FIG. 9 is an explanatory diagram showing a test method.

FIG. 10 is a front view of a conventional racket frame.

FIG. 11 is a main part reference explanatory view of a BB line part region in FIG. 10;

FIG. 12 is an explanatory view showing the front and side surfaces of a conventional racket frame.

FIG. 13 is a reference explanatory view of a main part of a conventional racket frame.

FIG. 14 is a reference explanatory view of a main part of a conventional racket frame.

FIG. 15 is an end view taken along the line CC of FIG. 14;

FIG. 16 is an explanatory view for explaining a relevant part of a section taken along line CC of FIG. 14;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Racket frame 2 Gut 3 Hitting part 4 Grip part 5 Shaft part 6 Top part 7 End part 8a section 8b node 9 belly 10 Mesh sheet 11 Sheet 12 Slit 13 Opening 14 Outer shell layer 15 Inner peripheral side 16 Outer peripheral side 17 Tube 18 Prepreg sheet 19 Frame molded body 21 Racket frame 22 Groove 23a Both sides 23b Both sides 24 Ball 31 Racket frame 32 Hitting part 33 Shaft part 34 Grip part 35 Outer shell layer 36 Outer side surface 37 Inner side surface 38 Gut insertion hole 39 Gut protection Groove 40 Gut protection member 41 Gut 42a Both sides 42b Both sides 43 Top section 51 Racket frame 52a Both sides 52b Both sides 53 Mesh piece 54 Top section 55 Grip section 56 Section 57 Outer side face 58 Inner side face 59 Wrinkle wrinkle

Claims (6)

[Claims] 1. A racket frame composed of an outer shell layer made of a fiber-reinforced resin having a large number of gut insertion holes penetrating the inner and outer peripheral side surfaces of a hitting portion. In addition, a mesh sheet made of a metal material having a specific gravity of 8.0 or more and a tensile elongation of 45% or more is integrally formed on the surface in the region of the frame cross section from the inner peripheral side to the outer peripheral side. A racket frame that is provided. 2. A groove is provided on an inner peripheral side surface of the hitting portion, and the mesh sheet is disposed in an area of a frame cross section excluding the groove area. The racket frame according to claim 1, wherein 3. The racket frame according to claim 1, wherein the mesh-like sheet is provided in a range of 50% to 80% of the entire circumference of the frame. 4. The racket frame according to claim 1, wherein the mesh sheet is a copper mesh. 5. The racket frame has a total length L of 0.7 L to 0.9 L from the end of the grip portion.
The racket frame according to claim 1, 2, 3, or 4, wherein the racket frame is disposed in an area corresponding to the range of L. 6. The total weight of the mesh-like sheet provided on the racket frame is set within a range of 0.3% to 1.0% of the weight of the racket frame before the gut is stretched. The racket frame according to claim 1, 2, 3, 4, or 5.