JP2000061005A - Racket frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a racket frame which is excellent in bouncing performance along with a higher strength and a higher rigidity. SOLUTION: A reinforced metal plate 3 comprising a metal with a specific gravity of 5 or less is provided after a prepreg 2 is arranged on the outer circumference of a tube 1. The metal plate 3 extends from one side of a grip part 1d of the tube 1 to the other side of the grip part 1d via a shaft part 1c and a face part 1a on one hand and the shaft part 1c on the other hand. After the metal plate 3 is externally fitted, it is further covered with the prepreg, and the tube 1 is expanded within a die while being heated at a specified temperature for a specified time to harden the prepreg. After releasing from the die, a burring is performed to obtain a racket frame product. The metal plate 3 is buried in an FRP 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racket frame for tennis, badminton, etc., and more particularly to a racket frame formed by compositely integrating a reinforcing metal plate such as titanium and FRP (fiber reinforced synthetic resin).

[0002]

2. Description of the Related Art As is well known, a racket frame such as a tennis racket frame has a face portion to which a gut is stretched, a grip portion gripped by a player, and a shaft portion connecting these.

A conventional racket frame is made of FRP, metal such as aluminum or titanium. A racket is constructed by stretching a gut (string) on the face portion of the racket frame.

In Japanese Unexamined Patent Publication No. 9-285569, a strip-shaped metal plate made of titanium or the like is provided on the side portion of the face, and particularly by providing the metal plate on the outer surface of the face side, It is described that the bending rigidity is increased, the deformation of the face portion upon a ball hit is reduced, and the resilience performance of the tennis racket is improved.

[0005]

When the reinforcing metal plate is provided on the outer surface of the racket frame, a strange appearance is generated.
In addition, since the bonding surface with the metal plate is only one surface of the metal plate, it is necessary to strictly control the molding process and the like in order to enhance the integrity (bondability) with the FRP of both, which may increase the cost. There is. When the reinforcing metal plate is provided only on the face side, the reinforcing effect is limited.

It is an object of the present invention to solve the above-mentioned conventional problems and to provide a racket frame which has high strength and rigidity, is excellent in resilience, and is easy to manufacture.

[0007]

The racket frame of the present invention is a racket frame made of fiber reinforced synthetic resin having a reinforcing metal plate, wherein the strip-shaped metal plate having a specific gravity of 5 or less is embedded at least in the shaft portion. It is characterized by being present.

In the present invention, a lightweight metal plate having a specific gravity of 5 or less is embedded in at least the shaft portion of the racket frame, and the shaft portion has high strength and rigidity. Since this metal plate is embedded in the FRP, there is no corrosion or scratch such as oxidation of the metal plate, and the metal plate and the FRP are excellent in integrity.

The reinforcing metal plate may be so arranged that its plate surface is parallel to the face surface of the racket frame, or may be so arranged as to be perpendicular to the face surface.

The reinforcing metal plate extends from one side surface of the grip portion to the face portion via one shaft portion, and extends to the other side surface of the grip portion via the other shaft portion, or has substantially the same shape as the racket frame. By embedding the metal plate of (1) on both sides of the racket frame, the strength and rigidity of the entire racket frame can be significantly increased. Moreover, the weight of the racket frame can be reduced by providing an opening in the metal plate as needed.
This opening can be formed by punching, for example.

As a material for the metal plate, a titanium alloy of a metal having a specific gravity of 5 or less (for example, Ti- which is a β-titanium alloy).
15V-3cr-3sn-3Al, Ti-22V-4A
1, Ti-20V-4Al-1Sn, Ti-16V-4
Sn-3Al-3Nb, α + β titanium alloy, nearβ
In addition to titanium alloys, aluminum alloys (especially duralumin) and magnesium alloys can be used. Magnesium alloy is a material that easily oxidizes and is difficult to handle.
Since it is buried inside, it does not come into contact with the outside air or moisture, so it does not easily corrode. In order to enhance the adhesion between the reinforcing metal plate and the FRP, it is extremely effective to roughen the surface of the metal plate (for example, sanding, blasting, etc.), or to perform degreasing treatment and primer treatment.

The thickness of the metal plate used in the present invention is 0.
2 mm to 1.0 mm is preferable, and 0.3 mm to 0.
5 mm is most suitable because it has good workability. Too thick,
Bending is difficult, and the rigidity is unnecessarily increased.
On the contrary, if it is too thin, the metal may be deformed by hitting it during the work.

The width of the strip-shaped metal is preferably in the range of 3 mm to 25 mm. Especially when set perpendicular to the face surface 10
mm to 22 mm is preferable, and the strip-shaped metal may be curved to the outside of the frame. The width of the metal plate is naturally smaller than the thickness of the racket frame. The metal plate is preferably punched or bent to have a shape suitable for being embedded in the racket frame. When bending a band-shaped metal, press it against the mold to match the shape of the racket, or
It is preferable to place it in a mold and perform bending using a pressing machine or the like. The radius of curvature (mm) of this bending is preferably 80R or more.

For safety of work, it is preferable that the edges of the strip-shaped reinforcing metal plate have rounded edges by punching or filing.

In the racket frame of the present invention, for example, an inflatable tube is used as a core material, an FRP prepreg is distributed around the core material, and a reinforcing metal plate is arranged at a required position so as to overlap with this, and then this metal plate is used. After being covered with prepreg, the tube may be expanded in a mold to be shaped into a product shape and heated to cure the prepreg.

Epoxy resin, nylon, vinyl ester and the like are preferable as the synthetic resin constituting the FRP, but epoxy resin is preferable in terms of strength, durability and cost. If a soft resin is adopted, a vibration absorbing effect can also be obtained.

As the reinforcing fiber, carbon fiber, boron fiber, alumina fiber, ultrafine iron wire, Ti-Si-C-
O-based fibers (trade name Tyranno fiber), aromatic polyamide fibers, aromatic polyester fibers, ultra-high molecular weight polyethylene fibers, and the like can be used, but carbon fibers are preferable in terms of cost.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments will be described below with reference to the drawings. 1 (a) and 1 (b) are perspective views of the tennis racket frame according to the first embodiment during manufacturing, and FIGS. 1 (c) and 1 (d) are a face portion and a grip of a racket frame product, respectively. It is sectional drawing of a part.

A tube 1 as a core material of a racket frame
Is a face portion 1a, a shaft portion 1c, and a grip portion 1.
d. The face portion 1a has a substantially oval shape.

Reference numeral 1b indicates a yoke portion forming a part of the face portion 1a.

After the prepreg 2 is distributed on the outer circumference of the tube 1, a reinforcing metal plate 3 made of a metal having a specific gravity of 5 or less is distributed. This metal plate 3 is a grip portion 1d of the tube 1.
From one side surface, one shaft portion 1c, face portion 1a,
It extends to the other side surface of the grip portion 1d through the other shaft portion 1c.

After the metal plate 3 is externally fitted as shown in FIG. 1 (b), the metal plate 3 is further covered with a prepreg (not shown), and then the tube 1 is expanded in the mold and at a predetermined temperature for a predetermined temperature. And heat to cure the prepreg. After demolding, deburring is performed to obtain a racket frame product.
As shown in FIGS. 1C and 1D, the metal plate 3 is the FRP of the product.
It is buried in 4.

If necessary, a foaming resin material may be injected into the tube for foaming.

A gut hole is formed in the manufactured racket frame, and a gut (string) is stretched using a grommet to form a racket used for play.

The racket frame thus constructed is made of FRP and a metal plate having a specific gravity of 5 or less, and is lightweight, has high strength and high rigidity.

Further, since the metal plate 3 is entirely covered with FRP, it is possible to provide the market with products having a wide variety of appearance and design by adopting FRP layers of various colors. Is.

FIG. 2A is a manufacturing intermediate view of a racket frame according to another embodiment, and FIG. 2B is a sectional view of a face portion of a racket frame product.

In this embodiment, a reinforcing metal plate 6 is provided along the outer surfaces of the shaft portion 1c and the grip portion 1d of the tube 1 via a prepreg (not shown in FIG. 2).
After covering the metal plate 6 with a prepreg, the tube is expanded in a mold and heated to obtain a racket frame product.

As shown in FIG. 2 (a), the face portion is composed of only FRP, and no reinforcing metal plate is provided. The cross section of the grip portion of the racket frame is the same as that shown in FIG.

FIG. 3 (a) is a manufacturing intermediate view of a racket frame according to another embodiment, FIG. 3 (b) is a cross-sectional view of a face portion of a racket frame product, and FIG. 3 (c) is a grip of the product. It is sectional drawing of a part.

In this embodiment, the tube 1 is sandwiched between the reinforcing metal plates 7 from both sides of the frame. (A prepreg is provided between the tube 1 and the metal plate 7, but not shown in FIG. 3.) The reinforcing metal plate 7 has a face portion 1a.
Face part 7 that overlaps (but excludes the yoke part 1b)
a, a protruding portion 7b that partially overlaps the yoke portion 1b, a shaft portion 7c that overlaps the shaft portion 1c, and a grip portion 1d.
And a grip portion 7d that overlaps with.

The grip portion 7d is provided with a plurality of openings 7e to reduce the weight of the metal plate 7.

After the metal plates 7 are distributed on both sides of the tube 1, prepregs are distributed so as to cover these metal plates 7, and the tubes are expanded in the mold and heated to produce a racket frame product. There is. As shown in FIGS. 3B and 3C, the metal plates 7 and 7 are embedded in the FRP 4.

[0034]

EXAMPLE A hard tennis racket was manufactured according to the procedure shown in FIG. As the reinforcing metal plate 3, a strip plate-shaped β titanium alloy (Ti-15V-3 having a plate thickness of 0.5 mm and a plate width of 10 mm) is used.
cr-3sn-3Al) was used to bend and create a product.

The surface of the β-titanium alloy metal plate subjected to this bending process (slowly rotating the sponge sander) was roughened with sandpaper (# 240). afterwards,
A degreasing treatment was performed using an organic solvent, and in order to improve the adhesion with the UD prepreg, a primer was applied and semi-cured in an oven.

First, two layers of UD prepreg were laminated on the outer periphery of the tube 1, a metal plate was set on the UD prepreg, and a required number of UD prepregs were laminated on the metal plate.

After placing this in a mold, the tube was inflated and heat-treated while applying pressure to form a racket. Then, the molded product was deburred and a gut hole was opened.

The results of comparing the rigidity value, the weight and the like of the tennis racket of the present invention and three types of commercially available tennis rackets are summarized below.

Table 1 below shows the results of evaluation by advanced players for each racket.

As described below, it was found that this racket frame was not so different from the weight of a general commercially available racket and had a good rebound.

[0041]

[Table 1]

As shown in FIG. 4, the amount of deflection was calculated from the deflection when the grip end of the racket was fixed over a length of 150 mm and a 6 kg weight was suspended at the top of the face.

Regarding the coefficient of restitution, the grip end of the racket is fixed, the ball hit by the tennis ball hitting machine is applied to the face center, and the ball speed Vr after hitting the gut is the speed Vo immediately before hitting the gut. The value when divided.

[0044]

As described above, according to the present invention, there is provided a racket frame which does not have a large weight and has good operability, good appearance, good repulsion performance, and high rigidity such as a shaft.

[Brief description of drawings]

1A and 1B are perspective views of a tennis racket frame according to a first embodiment in the process of being manufactured,
1C and 1D are cross-sectional views of a face portion and a grip portion of a racket frame product, respectively.

FIG. 2A is a manufacturing intermediate view of a racket frame according to another embodiment, and FIG. 2B is a cross-sectional view of a face portion of a racket frame product.

FIG. 3A is a manufacturing intermediate view of a racket frame according to still another embodiment, FIG. 3B is a cross-sectional view of a face portion of a racket frame product, and FIG. 3C is a cross-sectional view of the product. It is sectional drawing of a grip part.

FIG. 4 is an explanatory diagram of measurement of a deflection amount.

[Explanation of symbols]

1 tube 1a face part 1b Yoke part 1c shaft part 1d grip part 3,6,7 Reinforcing metal plate 4 FRP

Claims (4)

[Claims] 1. A racket frame made of fiber reinforced synthetic resin having a reinforcing metal plate, wherein the metal plate having a specific gravity of 5 or less is embedded in at least a shaft portion. 2. The reinforcing metal plate according to claim 1, wherein the reinforcing metal plate extends from one side surface of the grip portion to the face portion via one shaft portion and to the other side surface of the grip portion via the other shaft portion. Racket frame characterized by that. 3. The racket frame according to claim 1, wherein metal plates having substantially the same shape as the racket frame are embedded on both sides of the racket frame. 4. The racket frame according to any one of claims 1 to 3, wherein the reinforcing metal plate is provided with an opening.