JPH0614783Y2 - racket - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a racket which is a hitting tool for tennis, badminton, and the like.

[Conventional technology]

Disassembling the ball striking motion by the racket, that is, the swing, consists of a combined motion of the translational motion and the rotary motion of the racket. Of these, the translational motion involves the mass and the center of gravity of the racket, and the rotational motion involves the rotational inertia.

In the performance of the racket, the so-called heavy / light swing feeling is proportional to the mass of the racket and largely due to the size of the rotational inertia. As a recent favorite of general athletes, a racket that is easy to swing because it has a small swing, that is, has a small rotational inertia around the rotation axis of the swing is preferred. FIG. 7 schematically shows the movement of the tennis racket, and since the vertical axis X at the grip g of the racket R is the rotation axis of the swing, the above-mentioned demand for light swinging is satisfied. Therefore, it is sufficient to design so that the moment of inertia of the entire racket R about the rotation axis X becomes small.

Another important performance of racket usage is the surface stability of the racket. This surface stability will be described. In FIG. 7, when the ball is hit at a point off the central axis Y (for example, point h) in the gut surface of the racket R, the reaction force of the ball causes the reaction around the central axis Y. A large torque is generated, and the racket tries to rotate in the palm of the hand, which makes the direction of the hit ball unstable.
This rotation torque is considerably large, and the racket R
There is no way to prevent it by simply gripping the grip g to prevent the rotation of the. Thus, the magnitude of the resistance force to the torque around the central axis of the racket R generated by the hit ball is generally called surface stability. This surface stability can be measured as a moment of inertia about the central axis Y of the racket R. The larger the moment of inertia is, the higher the surface stability is, and it can be said that the ball, especially the racket, is hard to rotate.

When the inertia moment around the center axis of the racket is measured for various conventional tennis rackets, for example, a regular size racket made of wood is 100 × 10.
^-3 kg ・ sec ²・ cm or less, and carbon mid size (frame surface is larger than regular size) is 13
0 × 10 ^-3 kg ・ sec ²・ cm, oversize (frame size larger than mid size) 150 × 10
^-3 kg ・ sec ²・ cm, and the thickness racket (which is made thicker in the direction perpendicular to the gut surface of the frame) that has become more popular recently is about 155 × 10 ^-3 kg ・ sec ²・ cm. . From this, in terms of surface stability, regular size, mid size, over size, thick racket are excellent in this order, and in recent years the preference of athletes has been changed from regular size to mid size and over size. It can be said to be one of the causes.

As described above, in order to improve the surface stability, the moment of inertia about the central axis of the racket may be increased, so that the mass of the frame should be kept away from the central axis as much as possible. At this point, for example, an oversized racket has a larger frame surface than a regular size racket, so the lateral width of the frame is also large, and the distance from the frame to the center axis is large. As a result, the surface stability is improved. In addition, since the thickness of the thick racket increases as the thickness of the frame increases, the moment of inertia around the central axis is large and the surface stability is high.

As a method of increasing the surface stability, as described above, in addition to increasing the size of the racket or increasing the thickness of the frame, metal with a large specific gravity such as tungsten or lead is placed at the position where the width of the frame is maximum. A few grams,
By embedding or mounting as a weight,
There is a method to increase the moment of inertia about the central axis,
For example, it is said that by adding the weight as described above, it is possible to achieve surface stability similar to oversize even though it is a midsize.

[Problems to be solved by the device]

However, among the means for improving the surface stability in the related art as described above, the method of increasing the size of the racket is
As the size increases, it is difficult to operate the racket. Therefore, at present, a mid size having a frame area of about 90 to 100 in ² is predominant, but as described above, the mid size is inferior to the oversize in terms of surface stability and is unsatisfactory.

In the case of thick racket, the surface stability can be improved without increasing the area of the frame, so there is no decrease in operability or shaking due to the frame size, but since the frame thickness is thick, the rigidity increases, There are some drawbacks such as the moderate bending of the frame when hitting the ball, the feeling of hitting is hard, it is difficult to spin using the bending of the frame, and the operability during net play using the bending of the frame is poor. is there.

In the method of embedding the weight in the frame, the weight for increasing the moment of inertia about the center axis of the frame is locally concentrated, so the moment of inertia fluctuates greatly due to the position of the weight, variation in weight, error, etc. It was difficult to achieve stable performance, and it was also difficult to balance the weight of the racket, so practically sufficient performance was not obtained. In addition, since the process of embedding the weight increases in the manufacturing process, the manufacturing process is troublesome and costly.

In the above description, the tennis racket is taken as an example, but there are similar problems in rackets used for various sports such as badminton.

Therefore, the problem of this invention is that the moment of inertia around the center axis of the frame is large and the surface stability is high, and at the same time, the moment of inertia around the center axis of the swing is not too large and it is easy to swing, so it is excellent in performance as a racket. In addition, it is to provide a racket that is easy to manufacture and inexpensive.

[Means for Solving the Problems]

Among the inventions for solving the above-mentioned problems, the invention according to claim 1 is a racket provided with a gut protection member having a tubular snap-fit portion which is inserted into a plurality of gut insertion holes provided in the stringed portion of the racket frame. In the above, the gut protection member is made of a fluororesin having a specific gravity of 1.5 or more.

The gut protective member is a normal racket that is used to insert a tubular stopper part into the gut insertion hole in order to prevent the gut from rubbing against the gut when the gut is stretched on the stringed part. It can be implemented in various shapes and structures similar to those used. The gut protective member has an independent structure for each gut insertion hole, and there are a gut protective member consisting of only one splice part and a gut protective member having a structure in which a plurality of splice parts are connected. In this invention, any structure may be adopted.

The material of the gut protection member is a fluorine resin as a synthetic resin material having durability and strength capable of protecting the gut insertion hole and the gut of the stringed string portion and having flexibility capable of being deformed along the shape of the stringed string portion. In addition, a material having a specific gravity of 1.5 or more, preferably 1.7 or more is used.
The larger the specific gravity is, the larger the moment of inertia about the central axis can be. However, if the specific gravity is too large, the weight of the entire racket is increased and the operability is deteriorated. The following materials are preferable as specific materials.

Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA)… Specific gravity 2.17 Tetrafluoroethylene-hexafluoropropylene copolymer (FEP)… Specific gravity 2.17 Polychlorotrifluoroethylene (PCTFE)… Specific gravity 2.20 Tetrafluoroethylene -Ethylene copolymer (ETFE) ... Specific gravity 1.70 Polyvinylidene fluoride (PVDF) ... Specific gravity 1.77 In addition to using the above resin materials alone, a plurality of materials may be mixed to meet the above specific gravity conditions. It may be adjusted so that

According to a second aspect of the present invention, in the implementation of the first aspect of the invention, the gut protection member includes a fit portion and a band-like portion connecting the plurality of fit portions at the outer circumference of the stringed portion.

As described above, the gut protection member formed by connecting the plurality of spigot portions with the belt-shaped part has a structure adopted in a normal tennis racket or the like. Also in the present invention, a gut protection member for a normal tennis racket or the like is also provided. It can be implemented with the same structure as.
All the spigot parts inserted into the gut insertion holes around the entire stringed part may be connected by one strip-shaped part, or a strip-shaped part that is divided for each of the left and right arcuate sides of the stringed part. The stopper portions may be connected to each other, or the belt-shaped portion may be divided into a plurality of arc-shaped sides on one side.

According to a third aspect of the present invention, in the implementation of the second aspect of the invention, the gut protection member has a bulge portion on the outer surface side of the strip portion.

When the bulging portion is located as far as possible from the central axis of the racket, the moment of inertia about the central axis can be increased. For that purpose, it is better that the bulging part largely protrudes to the outer surface side of the band-shaped part, but it is carried out with an appropriate shape or size so as not to impair the workability when stretching the gut and the operability of the racket. It

The bulging portion may be formed on the entire band-shaped portion,
It may be formed only on a part of the strip portion. The farthest from the center axis of the racket in the arcuate stringed part of the racket is near the center of the left and right arcuate sides, so the bulge is the center of this arcuate side with respect to the strip part of the gut protection member. It is preferably formed at a position where it can be attached in the vicinity.

According to a fourth aspect of the present invention, in the implementation of the third aspect of the invention, the center of gravity of the bulging portion is on the grip side from the center of the gut surface of the racket with the gut protection member attached to the stringed portion of the racket frame. I am trying.

The center of the gut surface of the racket corresponds to the area center of the stringed portion, and is determined by the shape of the racket. The center of gravity of the bulging portion changes depending on the shape of the bulging portion and the position where the bulging portion is formed with respect to the strip-shaped portion of the gut protection member. With the gut protective member attached to the stringed part, the center of gravity of the bulging part should be located closer to the grip than the center of the gut surface, that is, closer to the center axis of the swing in the length direction of the racket. Keep it.

However, since the bulging portion is provided on the gut protective member attached along the arcuate side of the stringed portion, if the center of gravity of the bulged portion comes too close to the grip side along the arced side of the stringed portion,
Since the distance from the racket center axis Y also becomes small and the moment of inertia around the racket center axis Y becomes small, it is preferable to set it so that it does not come too close to the grip side.

[Action]

According to the invention of claim 1, by increasing the specific gravity of the gut protective member mounted on the outer circumference of the stringed portion as compared with the conventional one, the mass of the outer peripheral portion of the racket frame increases, and the weight around the central axis of the racket increases. The rotational moment of inertia can be increased to improve the surface stability, the mass is not extremely concentrated like when attaching a metal weight to the frame, and the weight is dispersed in the longitudinal direction of the frame,
Variations and fluctuations in the moment of inertia are eliminated, and weight balance is improved. Since the gut protective member itself is a component that is also used in the conventional racket, the manufacturing process may be the same as that of the conventional racket. Moreover, since fluororesin is used as the material for the gut protective member,
It is excellent in durability and strength, and can be flexibly deformed according to the shape of the stringed part, which is also excellent in the gut protection function.

According to the second aspect of the present invention, since the plurality of binding portions are integrally connected by the belt-shaped portion, manufacturing and handling are easy.

According to the third aspect of the present invention, since the gut protecting member has the bulging portion on the outer surface side, the moment of inertia about the central axis of the racket becomes larger.

According to the fourth aspect of the invention, the center of gravity of the bulging portion is close to the rotation axis of the racket, so that the moment of inertia about the rotation axis can be reduced.

〔Example〕

Next, the present invention will be described in detail below with reference to the drawings illustrating an embodiment.

The embodiment shown in FIGS. 1 to 3 shows the case of a tennis racket. FIG. 1 shows the entire structure of the racket, and FIG. 2 shows a part of it in an enlarged scale. And a grip portion 12 for gripping operation. The stringed portion 11 has a large number of gut insertion holes 1 at appropriate intervals over the entire circumference.
3 is formed through. The gut 20 is stretched vertically and horizontally through the gut insertion hole 13. However, since the gut 20 is stretched by applying a large tension, the edges of the gut 20 and the gut insertion hole 13 rub against each other and the gut insertion hole 13 is damaged. On the contrary, there is a problem that the gut 20 is easily cut. Therefore, the gut insertion hole 13 is fitted with a gut protection member 30, which is also called a grommet or the like and is made of a synthetic resin molded product or the like.

The gut protecting member 30 is composed of a tubular fit portion 31 that is inserted into each gut insertion hole 13 and a strip portion 32 that connects one ends of the plurality of fit portions 31 in a row. In a state where the racket frame 10 is attached to the tension string portion 11 of the racket frame 10, the tubular stoppers 31 of the gut protection member 30 are attached.
Is inserted into each gut insertion hole 13 from the outer peripheral side of the stringed portion 11, and the strip-shaped portion 32 of the gut protecting member 30 is arranged along the outer peripheral surface of the stringed portion 11. At both edges of the outer peripheral surface of the band-shaped portion 32, ridge-shaped bulging portions 33 are formed continuously along the longitudinal direction (see FIG. 3 (a)). The bulging portion 33 is provided only in a certain range in the central portion of the entire length of the gut protection member 30. The bulging portion 33 has an effect of increasing the moment of inertia about the racket central axis Y by protruding to the outer peripheral side of the gut protective member 30, and also serves to reinforce the gut protective member 30 and to stretch the gut 20. It also acts as a guide.

After mounting the gut protection member 30 as described above on the racket frame 10 by a normal means, the gut 20 is stretched in a predetermined pattern to complete the racket.

In the illustrated embodiment, when the gut protection member 30 is mounted on the racket frame 10, the bulging portion 33 projects to the outer peripheral side of the gut protection member 30, so that the mass of the gut protection member 30 is the center of the racket. Since it is distributed to the position away from the axis Y, the moment of inertia about the racket center axis Y becomes larger.

In order to reduce the moment of inertia about the swing rotation axis X, the shape of the gut protection member 30 should be set so that the mass of the gut protection member 30 is distributed to the position near the grip portion 12 that is the swing rotation axis X as much as possible. It is desirable to set. From this point, in the illustrated embodiment, the bulging portion 33
The center of gravity G of the whole is located closer to the grip than the center of the area of the gut surface of the racket. However, the bulge 33
When the center G of gravity of the racket approaches the grip side too much, the distance from the racket center axis Y also becomes small, and the moment of inertia around the racket center axis Y becomes small.
In the illustrated embodiment, the bulging portion 33 is arranged at an appropriate position in consideration of both conditions.

The shape of the gut protection member 30 is determined in consideration of the above-described conditions, but it is also possible to combine the shape and structure of the usual gut protection member 30 for various rackets.

In the illustrated embodiment, like a normal gut protection member,
The gut protection members 30 having the same shape are symmetrically attached to the left and right arcuate sides of the stringed portion 11, but the bulging portion 3 is included in the entire length of the gut protection member 30.
3 is formed and a portion without the bulge portion is formed by separate parts, and a bulge portion 33 is provided on each of the arcuate sides of the stringed portion 11 and a portion without the bulge portion. You may make it attach and combining.

As long as the racket structure according to the present invention has the structure and arrangement of the gut protection member 30 described above, in addition to the illustrated embodiment, regular, mid and large sizes, so-called thick racks, etc. It can be applied to rackets of various structures. Among them, particularly in combination with a mid-sized racket structure, the use performance such as surface stability and easiness of swinging can be best exhibited.

Next, the embodiment shown in FIGS. 4 to 6 is a case where the present invention is applied to a badminton racket. As shown in FIG. 4, the basic racket structure is similar to that of an ordinary badminton racket. Further, since both the badminton racket and the tennis racket are common in respect of the basic structure, the same parts as those in the above embodiment will be designated by the same reference numerals, and differences from the above embodiment will be mainly described. .

As shown in FIG. 5, the gut protective member 30 is provided on the stringed portion 1
Each gut insertion hole 13 of No. 1 is independent and does not have the band-shaped portion 32 in the above-mentioned embodiment. This is because the badminton racket has a severer weight limitation than a tennis racket and the like, and thus the gut protection member 30 and the racket are lightened by not providing the band-shaped portion 32. The fit portion 31 has a tubular shape that can be inserted into the gut insertion hole 13 almost entirely, and a hemispherical collar portion 34 is formed on the outer peripheral side of the fit portion 31. By fitting the hemispherical collar portion 34 on the outer peripheral side of the gut insertion hole 13, the gut protection member 30 is formed.
It is positioned so that it does not come out inside. With the gut protective member 30 attached to the gut insertion hole 13,
The gut protecting member 30 has its outer peripheral side embedded in the same surface as the outer peripheral surface of the stringed portion 11, and the bulging portion 3 in the above-described embodiment.
There is no configuration corresponding to 3.

In the case of a badminton racket, the ticket itself is lighter than a tennis racket, etc., and the repulsive force when hitting the shuttle is also small, so the moment of inertia around the racket center axis Y necessary to improve the surface stability is also It can be small. Therefore, the addition amount of the moment of inertia by the gut protection member 30 does not need to be so large, and as described above, the bulging portion 33 does not need to be provided in many cases. Also,
Not all the gut protective members 30 attached to the stringed portion 11 are made of a material having a high specific gravity, and only the gut protective members 30 at some places, such as near the center of the left and right sides of the stringed portion 11 having a high effect of increasing the inertia moment, have a specific gravity. It may be formed of a heavy material.

In the conventional general badminton racket, the weight of one gut protection member (commonly called stop) is 0.04 g, and 72 parts are attached to the entire racket, so the gut protection member 3
Total weight of 0 is about 3 g. On the other hand, in order to improve the surface stability and the speed of the shuttle using the gut protection member 30 of the present invention, a weight of about 2 g is added to the position away from the racket center axis Y. As described above, only some of the gut protective members 30 near the center of the left and right sides of the stringed portion 11 are changed to those having a large specific gravity according to the present invention, and other portions are the same as the conventional product. Even if it is used, the sufficient effect can be obtained.

FIG. 6 shows the gut protection member 30 shown in FIG.
This is an example in which 3 is added, and is applied when it is necessary to further increase the moment of inertia about the racket central axis Y.
Specifically, a spherical bulging portion 33 that is continuous with a hemispherical flange portion 34 provided on the outer peripheral side of the fitting portion 31 is formed, and like the bulging portion in the above-described embodiment, the racket. This has the effect of increasing the moment of inertia about the central axis Y.

As mentioned above, for badminton or tennis, etc.
The racket center axis Y, which is necessary to improve the surface stability and operability of the racket depending on the application and purpose of use
Since the specific setting range of the inertia moment around and the inertia moment around the swing center axis X or the weight distribution of the entire racket is different, the shape and structure layout of the gut protection member are selected according to the purpose of use. Shall be implemented.

-Example-Next, the specific example which manufactured the racket concerning this invention and measured the performance is demonstrated.

-Example 1-A midsize tennis racket having a frame area of 90 in ² was manufactured. The structure of the body and grip of the frame was the same as the conventional one. A gut protective member having the structure shown in FIG. 2 was manufactured. The material of the gut protective member was tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA) (specific gravity 2.17), and a gut protective member having a weight of 20 g was prepared by injection molding and mounted on a racket. The other manufacturing steps, the structure of parts, and the like are the same as those of the conventional racket, and detailed description thereof will be omitted. In order to compare the performance with the racket of Example 1 described above, the conventional gut protective member has exactly the same shape as that of Example 1, but is made of nylon 6 (specific gravity 1.14) and weighs 10 g. The gut protective member of No. 1 was prepared and mounted on the same racket as in Example 1.

Table 1 shows the results of measuring the moment of inertia If about the center axis of the frame and the moment of inertia Is about the center axis of the swing for the rackets of Example 1 and the comparative example as described above.

From the results shown in the table above, in Example 1 according to the present invention, the moment of inertia about the frame center axis is significantly larger than that of the comparative example, and the moment of inertia about the swing center axis is substantially the same. It was possible to significantly improve the surface stability without lowering the easiness of swinging, and it was demonstrated that both have excellent surface stability and easiness of swinging. As a result of actually trial-driving the racket, it was confirmed that the racket of Example 1 had the surface stability equal to or larger than the oversize even though it was the mitt size.

-Example 2-In place of the gut protective material of Example 1, a racket was manufactured by using a gut protective member made of polyvinylidene fluoride (PVDF) (specific gravity 1.77) and having a weight of 28 g. The manufacturing conditions other than the above were the same as in Example 1.

The respective moments of inertia of the manufactured racket were as follows.

Around frame center axis If = 155 × 10 ⁻³ kg · sec ² · cm Swing center axis around Is = 50 × 10 ⁻³ kg · sec ² · cm As a result, the racket of Example 2 is the same as that of Example 1. ,
It was found that both the surface stability and the ease of swinging were excellent.

[Effect of device]

Since the racket according to the present invention described above is provided with the gut protection member made of a material having a large specific gravity on the outer periphery of the frame, the moment of inertia around the center axis of the frame becomes large, which is important for the performance of the racket. The surface stability is very good. Further, as compared with the conventional technique in which a local metal weight is attached to the frame, the weight can be dispersed in a wide range on the outer periphery of the frame, so that variations or errors in the moment of inertia and the weight balance are less likely to occur.
It can exhibit stable performance.

The gut protective member itself is a component that is also used in conventional rackets, and since only a material with a large specific gravity is used as the material for this gut protective member, the structure, number of components, and manufacturing process of the racket are The racket is exactly the same as the racket, and it is easy to manufacture and the manufacturing cost is low. Therefore, unlike the conventional racket with a weight, it is possible to solve the problem that it takes time and effort to manufacture and costs are high.

Moreover, since the fluorocarbon resin is used as the material for the gut protective member, a material having a large specific gravity described above can be obtained without the trouble of mixing metals, and strength, durability, flexibility, etc. In terms of the performance required for the gut protective member, it is also extremely excellent.

[Brief description of drawings]

FIG. 1 is a partial sectional front view of an entire tennis racket showing an embodiment of the present invention, FIG. 2 is an enlarged half sectional view of a mounting portion of a gut protective member, and FIG. An enlarged cross-sectional view of the gut protection member taken along the line, FIG. 3 (b) is FIG.
FIG. 4 is an enlarged sectional view of the gut protective member taken along line V, FIG. 4 is a front view of the entire badminton racket showing another embodiment, and FIG. 5 is an enlarged sectional view of a mounting portion of the gut protective member.
FIG. 6A is a cross-sectional view showing another embodiment of the gut protecting member, FIG.
FIG. 7B is a side view, and FIG. 7 is a perspective view for explaining a motion state of the racket. 10 ... Racket frame, 11 ... String part, 13 ... Gut insertion hole, 20 ... Gut, 30 ... Gut protection member, 31 ...
Cylindrical stopper part, 32 ... band-shaped part, 33 ... bulging part, 34 ... collar part

Claims (4)

[Scope of utility model registration request] 1. A racket provided with a gut protection member having a tubular fit-out portion that is inserted into a plurality of gut insertion holes provided in the stringed portion of the racket frame, wherein the gut protection member has a specific gravity of 1.5 or more. A racket made of resin. 2. The racket according to claim 1, wherein the gut protection member comprises a fit portion and a band-like portion connecting a plurality of fit portions on the outer circumference of the stringed portion. 3. The racket according to claim 2, wherein the gut protection member has a swollen portion on the outer surface side of the strip portion. 4. The racket according to claim 3, wherein the center of gravity of the bulging portion is on the grip side from the center of the gut surface of the racket with the gut protective member attached to the stringed portion of the racket frame. .