JPH0466593B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a racket used for sports such as tennis, badminton, and skateboarding, and more specifically, to a racket in which a ball hitting surface made of strings can be easily replaced in a short time. Regarding.

[Conventional technology]

The ball hitting surface of a racket used for sports such as tennis, badminton, and skateboarding is generally constructed by strings made of nylon, sheep gut, whale sinew, etc. stretched over a racket frame. These strings have a limited lifespan and must be replaced if they are cut or their performance deteriorates.

Changing strings requires special equipment and techniques, so a professional is usually hired to replace the strings. However, if there is an urgent need, it may not be possible to do so in time, so it has become common sense for intermediate-level players and above to always have multiple rackets on hand. However, preparing multiple rackets like this is not only difficult to carry, but also economically undesirable. Also,
In some cases, when the string broke during a match and the racket was replaced, the grip, weight, frame flex, etc. were slightly different, causing a loss of pace, which became a turning point and led to the loss of the match. It happens often.

The rebound of the ball depends on the material of the string, physical properties such as elongation and modulus of elasticity, gauge, tension, etc., so it must be adjusted according to the weather and physical condition of the day.

However, even if you adjust the repulsion of the ball, it is often not possible to adjust it depending on the weather and physical condition of the day, and in that case, it is still necessary to replace the string or the racket itself. .

On the other hand, there has recently been a remarkable trend towards colored strings, with vivid colors such as lemon, pink, and turquoise blue, combinations of these, and multi-colored strings using a single string with multiple colors being used. I'm getting old. It is desirable to be able to change the color of the strings to suit the playing day, time of day, preference, etc. However, with current rackets, special equipment and techniques are required to change the strings as described above. Re-covering is not commonly used unless it is cut or performance deteriorates.

Therefore, in order to facilitate string replacement,
Various inventions have been introduced.

For example, the invention described in Japanese Utility Model Application Publication No. 57-7565 provides an insertion opening into which a string-strung string part (string cassette) can be inserted on the side surface of the racket frame, and the cassette is inserted and fixed from there. Alternatively, a mounting stopper that can be opened and closed is provided on the front surface of the racket frame, and the cassette is thereby fixed to the racket frame.

In addition, the invention described in JP-A-60-12078 is
Drop the cartridge cassette into the slit on the side of the racket frame,
It is fixed to the frame with leaf springs and screws.

Furthermore, the invention described in JP-A No. 62-49870 is
A frame portion (cassette) having a shape corresponding to the gut frame shape of the racket is engaged with the racket through a connecting portion such as a thumb screw.

[Problem that the invention seeks to solve]

Among the above inventions, the invention described in Japanese Patent Application Laid-Open No. 62-49870 is for making it possible to try out a racket without stringing it on a normal racket frame. It is in such a state that it cannot withstand the strong impact of hitting the ball. Therefore, the above problem cannot be fundamentally solved by this invention.

The invention described in Japanese Utility Model Application Publication No. 7565/1983 and the invention described in Japanese Patent Application Publication No. 1983-
As mentioned above, the invention described in Publication No. 12078 is equipped with various mechanisms for changing strings on the racket frame itself, and can withstand strong impact when hitting a ball. It has some drawbacks.

Namely, disadvantages include (a) the racket becomes heavier, (b) the racket frame cannot be made using conventional materials and manufacturing methods, and (c) the durability of the metal fittings, etc. is not sufficient. It has.

The weight of a racket is one of its important characteristics, and the lighter it is, the better it is, so increasing the weight as in (a) is not allowed. Furthermore, since the higher the strength, the better, it is also undesirable to have parts with poor durability as in (c).

The fact that conventional materials and manufacturing methods cannot be used means that new materials and manufacturing methods must be used to develop products with the same performance as before, resulting in higher costs.

Also, using materials that are different from conventional ones means that
This means that the feel at impact, which is important for a racket, is far different from that of conventional rackets, which may cause users to shy away from it.

Therefore, with the above two inventions, it is not possible to manufacture a racket with the same performance as the conventional racket at the same cost, and even if there is an advantage of replacing strings using a cassette, the disadvantages outweigh this and make it completely useless. It becomes impractical.

This invention was made in view of the above circumstances, and allows the strings that make up the ball-hitting surface to be easily replaced in a short time, and has the same performance as conventional ones, and at the same cost. The purpose is to provide a racket that can be manufactured.

[Means for solving problems]

In order to achieve the above object, the cassette rack of the present invention has a ball hitting surface A formed in a ring-shaped frame member 1a, as shown in FIG. A cassette frame 1 having a protruding strip 1b extending in the circumferential direction formed on the outer circumferential surface of the cassette frame 1, and a cassette frame holding portion whose inner dimensions can be enlarged/reduced and which surrounds the outer circumferential surface of the cassette frame with a partially open shape. 2a, a pair of arm portions 2c, 2 extending from the open portion 2b in a direction away from the cassette frame and separated at their tips;
c is constructed, and the tips of both arm portions 2c, 2c are fixed to and removable from the grip 4, and the protruding strip of the cassette frame is fitted onto the inner circumferential surface of the cassette frame holding portion facing the cassette frame. The racket frame 2 is provided with a racket frame 2 in which a groove 2d is formed.

[Effect]

Next, the operation of the present invention will be explained with reference to FIG. 1 and FIGS. 2 a to 2 c.

First, as shown in FIG. 2a, the cassette frame 1 on which the ball hitting surface A is formed is fitted into the cassette frame holding portion 2a of the racket frame 2.

As racket frame 2 of cassette frame 1,
Traditionally used for rackets include wood-based materials, metal-based materials such as steel, aluminum, and titanium alloys, and fiber-reinforced plastic materials that use so-called prepregs, which are fiber base materials such as carbon, glass, aramid, ceramics, and boron impregnated with resin. material,
It can be used as is. The manufacturing method is also the same as the conventional one, and is not particularly limited.

The cassette frame 1 can also be made by cutting the reinforcing fibers used in the fiber-reinforced plastic system mentioned above into appropriate lengths, mixing them with resin, and injection molding them.
and a racket frame 2 can be manufactured.

In injection molding, the string 3, which has been made into a mesh shape in advance, is inserted into the mold, and resin is injected into the mold to integrally mold the ring-shaped frame material 1a. This process can be omitted and mass production becomes possible.

Further, if the mesh-like ball hitting surface A is also made of resin by injection molding, mass production becomes possible. Moreover, with these injection molding methods,
This is advantageous in terms of strength because it eliminates the need for holes in the cassette frame 1 to pass the string through.

As the string 3, a desired string can be selected from those conventionally used, and the string can be stretched to the cassette frame 1 by a known method for rackets. The tensioning density of the strings is not particularly limited, and may be set to suit the ball game in which the racket is used and the preference of the user.

Next, as shown in FIG. 2b, the distance between the open portions 2b of the racket frame is reduced by bringing the paired arm portions 2c, 2c closer to each other. Then, the grips 4 are fitted onto the arm portions 2c, 2b to fix the contracted state (FIG. 2c). Then, the cassette frame 1 is tightened by the cassette frame holding part 2a, and the protruding strip 1b and the groove 2 are tightened.
d are fitted together and both are fixed.

The grip 4 may be fixed to the arm portion 2c by screwing or by using a reverse taper. If necessary, a stopper such as a thumbscrew may be used as an auxiliary device. The grip 4 may be an ordinary grip made of plastic such as urethane foam, wood, or the like, and the outer periphery of the grip 4 is covered with natural or artificial leather. Furthermore, by preparing grips of various sizes, it becomes possible to change grips depending on the conditions of the day.

In addition, 6, 6 in the figure is a yoke divided into two parts, and as shown in FIG. 2c, the arm portions 2c,
When 2c are fixed close to each other, they are brought together.

At this time, as shown in Figure 1, these yokes 6
Between them, there is a dovetail groove 6a and a dovetail shape 6 that fits therein.
The contracted state may be fixed by providing a connection structure such as a dovetail structure consisting of b and connecting the two.

That is, the cassette frame holding portion 2a may be fixed in the contracted state by fitting the grips 4 to the arm portions 2c, 2c, or by using the yoke 6. Of course, both may be used together.

When replacing the cassette frame 1, in the reverse order of the above process, first remove the grip 4, use the elasticity of the cassette frame holding portion 2a to widen the gap between the open portions 2b, and then remove the old cassette frame 1. Then, a new cassette frame 1 may be fixed to the racket frame 2 according to the above steps.

When fitting the cassette frame 1 to the cassette frame holding part 2a of the racket frame, it is also conceivable to provide a hinge at the top of the cassette frame holding part to facilitate opening of the opened portion 2b. However, as mentioned above, this would complicate the structure and create weak parts. If the racket frame 2 is made of normal materials,
Even when the cassette frame holding portion 2a is bent and opened due to its elasticity, a sufficient distance can be maintained, so in the present invention, the elasticity of the cassette frame holding portion 2a may be used to widen the distance between the opened portions 2b.

Various fixing structures are possible between the cassette frame 1 and the cassette frame holding part 2a, but in this invention,
As mentioned above, it is necessary to fit the protrusion 1b and the groove 2d. This is due to the following reason.

In making the ball hitting surface into a cassette as in the present invention, the most important characteristics are the strength and rigidity of the racket and the fixing structure of the cassette frame 1 that can withstand the strong impact when hitting a ball. Also, as mentioned above,
It is also important that the feel at impact remains the same as before. Therefore, it is necessary to select the weight, cross-sectional shape, or fixing structure of the frame from these viewpoints.

Figures 3a, b, and c show cross-sectional shapes of a racket prototyped by the inventors in order to study the fixing structure between the cassette frame 1 and the cassette frame holding part 2a.
Figure b shows the cross-sectional shape of a racket commonly used in the past. These are made from carbon fiber reinforced plastic.

FIG. 3a shows a fixing structure according to the present invention, in which a protruding strip 1b is formed on the cassette frame 1, and a groove 2d is formed on the cassette frame holding portion 2a. Note that 1c in the figure represents a grommet (gut hole) through which the string is passed. The same applies to other figures, 5c in Figures 3 b to d,
1'c each represents a grommet.

According to the fixing structure according to the present invention, the combined cross-sectional area and the weight of the racket head are the same as those of the conventional structure shown in FIG. 3b, and the tension when the string is stretched is also reduced. endure,
A product with sufficient strength can be obtained. Rigidity can also be made to the same level as conventional ones.

On the other hand, as shown in Fig. 3c, in a structure in which a groove 1'd is provided on the cassette frame 1' side and the racket frame 2' is fitted thereto, high stress is applied to the cassette frame 1' side. is concentrated, and the rigidity of the racket frame 2' in the out-of-plane direction is insufficient. For this reason,
As shown in FIG. 3c, if the combined cross-sectional area of both is the same as that of FIGS. 3a and 3b, the strength and rigidity will be insufficient.

If we try to obtain the same level of strength and rigidity as those in Fig. 3 a and b with the fixing structure shown in Fig. 3 c, Fig. 3 d
As seen in Figure 3, the cross-sectional area has increased significantly, and the weight of the head has also increased by 60% compared to the one shown in Figure 3a. As mentioned above, reducing the weight of the racket and the top light is one of the important performances of the racket, so an increase in weight is not allowed.

Therefore, in this invention, the above-mentioned figure 3 a
Therefore, it is necessary to adopt a fixed structure.

According to the cassette rack of the present invention as described above, since the cassette frame 1 can be replaced, the basic performance of the racket, such as a grip that is familiar to the user, bending of the frame, moment of inertia during swing and twisting, and balance, can be improved. Only the ball hitting surface can be easily replaced in a short time without changing the ball hitting surface.

The attachment and detachment of the cassette frame 1 to the cassette frame holding portion 2a of the racket frame is achieved by varying the interval between the open portions 2b of the racket frame, that is, by bending the cassette frame holding portion 2a.
A complicated mechanism for fixing the cassette to the racket frame becomes unnecessary. Therefore, the racket frame 2 can be made using the same materials and the same manufacturing method as conventional rackets, making it possible to obtain a racket that is as lightweight and strong as conventional rackets.

Although the cassette rack of the present invention has been described so far based only on the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments.

For example, in the above embodiment, the grip 4 is used to shorten the interval between the open portions 2b of the racket frame and fix the cassette frame 1 to the cassette frame holding portion 2a. , by the yoke 6, or by a combination of both. The yoke 6 does not need to be separated into two parts, and may be provided biased toward one of the arm portions 2c.

The shape of each part is not limited to the above embodiment.

In short, if the racket frame is fitted into the cassette frame holding part of the racket frame and the internal dimensions of the cassette frame holding part are reduced so that the cassette frame is tightened and fixed, other configurations are not particularly important. It is not limited.

〔Example〕

Next, embodiments of the invention will be described.

Example 1 A cassette frame 1 and a racket frame 2 shown in FIG. 1 were made using a known method using prepreg made of carbon fiber and epoxy resin. The fixing structure for both was as shown in Figure 3a.

After forming the ball hitting surface A by stretching a nylon string around the cassette frame 1 with a tension of 40 pounds, it is fitted onto the racket frame 2 and fixed with a separately prepared grip made of urethane foam and leather. I got a racket.

When the resulting racket was tested, it was found that both the feel at impact and the durability were almost the same as those of conventional rackets.

In addition, it was possible to easily replace the cassette frame 1 with the cassette frame 1, which had a string prepared in the same manner stretched with a tension of 50 pounds.

Example 2 A cassette frame 1 having a cross-sectional shape as shown in FIG. 3A was made from a steel pipe, and a ball hitting surface A was formed by stretching a nylon string under a tension of 50 pounds.

The obtained cassette frame 1 was fitted into a racket frame 2 made of wood having the cross-sectional shape shown in FIG. I got a racket.

When the resulting racket was tested, it was found that both the feel at impact and the durability were almost the same as those of conventional rackets.

In addition, it was possible to easily replace the cassette frame 1 with the cassette frame 1, which had previously prepared strings stretched at a tension of 40 pounds.

〔Effect of the invention〕

The cassette rack of the present invention is as described above, and includes a cassette frame and a racket frame,
The cassette frame is fitted into the cassette frame holding part of the racket frame, and the inner dimensions of the cassette frame holding part are reduced, so that the cassette frame is tightened and fixed, making it easy to tighten the string that forms the ball hitting surface. can be replaced in a short time,
Moreover, it has the same performance as the conventional one and can be manufactured at about the same cost.

In particular, according to the present invention, the structure for attaching the cassette frame to the racket frame in a replaceable manner as described above has a large effect on the strength and durability of the racket, as well as on performance in use such as swing characteristics and feel at impact. There are no seams or extra parts, so even though the cassette frame can be easily replaced, it can provide the same level of durability and usability as a normal racket.

In other words, since the cassette frame and the cassette frame holding portion of the racket frame are fixed by a fitting structure using protrusions and grooves provided on the inner and outer circumferential surfaces of each other, there is no need to increase the weight of screws or metal fittings, etc. Since there are no protruding parts, there is no increase in the weight of the metal fittings or deterioration in usability due to the protruding parts, and the cassette frame can be easily attached to the cassette frame.

In addition, the racket frame has a cassette frame holding section and a pair of arms that extend from this to the left and right. Since there are no longitudinal seams along the entire length of the parts, there is no need for metal fittings or connecting parts to connect the seams.

As a result, there is no need to worry about the strength and durability of the racket frame decreasing at the joints, and the racket provides elastic bending of the entire racket when hitting a ball, transmission characteristics of impact vibrations, and other properties that affect the feeling of hitting a ball and performance in use. It is no different from a normal racket.

In addition, the racket frame in which the cassette frame holding part and the pair of arm parts are integrally formed can have the tips of both arm parts widened to the left and right, so that the internal space of the cassette frame holding part into which the cassette frame is inserted can be expanded. It becomes possible to widen the cassette frame to make it easier to insert the cassette frame, and the work of replacing the cassette frame becomes extremely easy.

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view showing one embodiment of the cassette rack of the present invention, Figs. 2 a to c are explanatory views illustrating how the cassette frame is replaced in the cassette rack of this embodiment, and Fig. 3 a 3 is a sectional view showing the fixing structure between the racket frame and the cassette frame in the cassette racket of the present invention, FIG. 3b is a sectional view of a conventional racket frame, and FIGS. FIG. 3 is a cross-sectional view showing the fixing structure between the racket frame and the cassette frame. A... Ball hitting surface, 1... Cassette frame, 1a... Ring-shaped frame material, 1b... Convex strip, 2... Racket frame, 2a... Cassette frame holding portion, 2b... Open portion, 2c ...Arm part, 2d...groove.

Claims (1)

[Claims] 1. A cassette frame in which a ball hitting surface is formed in the ring-shaped frame material and a protruding strip extending in the circumferential direction is formed on the outer circumferential surface of the ring-shaped frame material, and this cassette frame is partially open. The cassette frame holder has a cassette frame holder that surrounds the outer circumferential surface of the cassette frame and whose inner dimensions can be enlarged and contracted, and a pair of arms extending from the open part in a direction away from the cassette frame and having separate tips are configured. A racket in which the ends of both arm parts are fixed to and detachable from the grip, and a groove is formed on the inner circumferential surface of the cassette frame holding part facing the cassette frame, into which the protrusion of the cassette frame is fitted. A cassette rack rack comprising a frame, the cassette frame is fitted into a cassette frame holding part of the racket frame, and the cassette frame is tightened and fixed by reducing the inner dimension of the cassette frame holding part.