JPH07275403A - Gut for tennis racket - Google Patents

Abstract

PURPOSE:To obtain gut which has a good repulsion characteristic, controllability, etc., has excellent durability and heat resistance and is inexpensive by forming the gut in such a manner that the storage spring constant thereof when a specific sinusoidal strain is applied on the gut exhibits a specific value at a specific sample length and in the state of initial load. CONSTITUTION:The synthetic fiber gut for tennis rackets is so formed that the storage spring constant when the sinusoidal strain of a frequency 10Hz and one amplitude 1.5% is applied thereon in the state of the sample length 40mm and initial load 27kg of the conditions approximate to the conditions of actually hitting a ball exhibits 80 to 190kg/cm. As a result, the repulsion characteristic, controllability, etc., at the time of hitting the ball are improved. The gut 1 is formed into a multifilament structure formed by doubling and twisting about 3 to 2500 pieces of, for example, the fibers 2 and adhering and coating the fibers with a resin. A polyamide resin, such as nylon, is used for the fibers 2. The size of the fibers is set at 6 to 3000 denier, the pitch of the twists at 3 to 7mm/turn and the stretching magnification of heating and stretching at 0 to 30%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tennis racket gut, and more particularly to an inexpensive tennis racket gut having excellent resilience, controllability, shot feeling, and hold feeling, and excellent durability and water resistance. It is a thing.

[0002]

2. Description of the Related Art Conventionally, as a gut for a tennis racket, a natural gut in which animal muscles such as intestines of cattle and sheep and whale muscles are appropriately twisted and coated with a resin has been provided. This natural gut has great elongation, good resilience, controllability, shot feeling, and hold feeling, but durability,
There are problems of low water resistance and high price.

On the other hand, conventionally, there have been provided guts for tennis rackets made of various synthetic fibers. This synthetic-fiber tennis racket gut has good durability and water resistance, but is inferior in resilience to natural gut,
The physical properties are set so that the resilience, etc. as close as possible to natural gut can be obtained. Specifically, in the case of the conventional gut made of synthetic fiber, the elastic modulus in the dynamic viscoelastic spectrum that can be measured only under an extremely low load (3 kg or less), or 5
The initial elastic modulus, Young's modulus, etc. in a static tensile test of 00 mm / sec or less are set to values close to those of natural gut. According to the measurement results such as the elastic modulus under this low load and the initial elastic modulus in the static tensile test, since the natural gut has a high elastic modulus, the characteristic of the synthetic resin gut is that the elastic modulus is The higher it is, the closer it is to natural gut.

[0004]

However, in general, a gut for a tennis racket is 18 kg to 32 kg (40 lb to
70 lb) is used with the racket stretched, and the time of contact with the ball when hit is 3 /
It is between 1000 seconds and 5/1000 seconds. Therefore, the above-mentioned conventional tennis racket gut is merely trying to make the physical properties of the gut for a tennis racket close to those of a natural gut under conditions that are significantly different from the actual usage conditions.

On the other hand, the present inventors evaluated the physical properties of the gut under the conditions as close as possible to the actual use conditions. Specifically, a sample length of 40 cm and an initial load of 27 kg (6
0 lb) gut with a half amplitude of 1.5% 10
The storage spring constant K1 was measured by applying a sinusoidal distortion of Hz.

Here, as the sample length, as shown by L in FIG. 3A, the upper and lower ends of the gut 11 are chucked to the chuck 12.
Chuck 12 when mounted on A and 12B and suspended
It is the length of the gut 11 between A and 12B. Further, the initial load is a load statically applied as shown by F in FIG. 3 (B) from a state where no load is applied to the lower end of the gut 11.
Further, as shown by A in FIG. 3 (C), the one-sided amplitude is the amplitude of the upper side and the lower side (one side) when the initial load is applied to vibrate vertically. To display this one-sided amplitude as a percentage, use the following formula.

(One-sided amplitude) = (One-sided amplitude A) / {(Sample length L) + (Spread by initial load F)} × 100 (%)

The initial load of the gut was set to 27 kg because the tension when the racket was stretched (18 kg to 3 kg).
2 kg). Also, set the half amplitude to 1.
The setting of 5% is about 3 for a gut stretched by 27 kg.
Elongation that occurs when a 0 m / sec ball collides (1-
2%). The storage spring constant K1 measured under these conditions is 123 kg / cm for natural gut.
And 190 kg / c for a conventional synthetic fiber gut
It was m or more. As described above, the conventional synthetic fiber gut has a smaller elongation under actual conditions when hitting the ball than the natural gut, and has good ball resilience, controllability, shot feeling, and hold feeling. Turned out not to be.

The present invention solves the problems in the conventional gut for tennis racket made of synthetic fiber, has good resilience, controllability, shot feeling, and hold feeling, and is excellent in durability and water resistance. The purpose of the present invention is to provide an inexpensive synthetic fiber tennis racket gut.

[0010]

Therefore, according to claim 1, the storage spring constant is 80 to 80 when a sine wave distortion of a half amplitude of 1.5% and a frequency of 10 Hz is applied under the condition of a sample length of 40 mm and an initial load of 27 kg. A gut for a tennis racket made of synthetic fiber, which is characterized by having a weight of 190 kg / cm.

Here, the storage spring constant is the load amplitude Δ
Let F be the amplitude of the deflection, ΔL be the phase difference between the load and the deflection, and be defined by the following equation.

K1 = (ΔF / ΔL) * cos δ

[0013]

In the gut for tennis racket made of synthetic fiber according to the present invention, the condition close to that of actually striking a racket to hit a ball, that is, a sample length of 40 mm and an initial load of 27 kg, a frequency of 10 Hz, One-sided amplitude 1.5
The storage spring constant is 80 to 19 when a sine wave distortion of
Since it is set to 0 kg / cm, the ball is sufficiently deformed at the time of hitting, and the resilience, controllability, hit feeling and ball holding feeling are good.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in the drawings. FIG. 1 shows a gut 1 for tennis racket made of synthetic fiber according to the first embodiment of the present invention (hereinafter,
Abbreviated as "gut". ), The first embodiment has a multifilament structure in which about 3 to 2500 fibers 2 are twisted together and bonded and coated with resin. This fiber 2 is a fiber made of a polyamide resin such as nylon 66 or nylon 6, and has a fiber thickness of 6 to 300.
It is 0 denier.

The twist pitch of the fiber 2 is set to be short, and is set to 3 mm / turn or more and 7 mm / turn or less. Furthermore, the draw ratio of the heat drawing described below is 0 to 3
It is set to 0%.

In the gut 1 of the first embodiment, fibers 2 made of polyamide resin having a low elastic modulus are used, and the fiber thickness, the number of fibers, the twist pitch, and the draw ratio are appropriately set within the above range. As a result, the elastic physical properties under conditions close to those when actually striking a racket and hitting it are brought close to those of natural gut. That is, in the first embodiment, the sample length is 40 mm and the initial load is 27 kg (60 lb) corresponding to the state in which the racket is actually stretched.
Elongation that occurs when a sec ball collides (1-2%)
Corresponding to 1.5% of one-sided amplitude and frequency of 10 Hz
The storage spring constant K1 when the sine distortion of
The range is set to 90 kg / cm.

Here, the storage spring constant K1 is defined by the following equation, where ΔF is the amplitude of the load, ΔL is the amplitude of the deflection, and δ is the phase difference between the load and the deflection, as shown in FIG. .

K1 = (ΔF / ΔL) * cos δ

In the gut 1 of the first embodiment, as described above,
Since the storage spring constant K1 under conditions close to those when actually striking a racket and hitting the ball is set close to the value of the storage spring constant of natural gut (about 123 kg / cm) under the same conditions. , When it is actually stretched on a racket and a tennis ball is hit, it deforms sufficiently. Therefore, the gut 1 of the first embodiment has good resilience, holds the ball well, and has good shot feeling and controllability.

Further, since the gut of the first embodiment is made of polyamide resin, it has better durability and durability than natural gut.
Good water resistance.

The gut according to the first embodiment is manufactured by the following known method. First, a resin in a pellet state is spun and stretched to form a fiber. Next, draw 3 or more fibers together, or use a twisting machine to 3 mm / turn or more 7
Twist together at a pitch of mm / turn, and bond and coat with nylon, urethane, or other resin.
Furthermore, after coating, heat drawing is performed at a draw ratio of about 0 to 30%.

In the gut of the second embodiment, the fiber 2 is a fiber made of polyvinylidene fluoride resin. In this case, the fiber thickness is 400 to 3000 denier and the number of fibers is 3.
To 400, a twist pitch of 3 to 30 mm / turn, and a draw ratio of 0 to 30%,
The storage spring constant K1 is set to a range of 80 to 190 kg / cm when a sine wave distortion having a half amplitude of 1.5% and a frequency of 10 Hz is applied in a sample length of 40 mm and an initial load of 27 kg. As in the case of the first embodiment, the gut of the second embodiment also deforms well when actually strung on a racket and hits the ball, resulting in resilience, ball holding feeling, hit feeling, and controllability. It is good. Further, since it is made of polyvinylidene fluoride resin, it has better durability and water resistance than natural gut.

The present invention is not limited to the above embodiment, but various modifications can be made. For example, in the above example, the gut is formed of fibers made of polyamide resin or polyvinylidene fluoride resin, but the fibers constituting the gut are not limited to this, and fibers made of a resin having a low elastic modulus are used. If so, for example, fibers made of modified nylon or the like may be used.

[0024]

Experimental Example An experiment was conducted to confirm the effect of the present invention. In this experiment, the nylon 66 gut (Experimental Example 1 to Experimental Example 4), the nylon 6 gut (Experimental Example 5), and the polyvinylidene fluoride gut (Experimental Example 6) according to the present invention were used.
-Experimental example 8) was prepared. The fiber thickness, the number of fibers, the pitch of twists, and the draw ratio of each experimental example were set within the range of the above-described examples as shown in Table 1 below, and the sample length was 40 mm and the initial load was 27 kg / cm. The storage spring constant is 80 when a sine wave distortion with an amplitude of 1.5% and a frequency of 10 Hz is applied.
It is set in the range of up to 190 kg / cm.

[0025]

[Table 1]

In this experiment, the guts of Comparative Examples 1 to 4 shown in Table 2 below were prepared. Comparative Example 1 is a comparative example corresponding to Experimental Examples 1 to 4, and nylon 6
6 made, but the storage spring constant K1 under the above conditions is 1
It is set to 91 kg / cm. Comparative Example 2 is Experimental Example 5
Is a nylon 6 comparative example, and the storage spring constant under the above conditions is set to 207 kg / cm. Comparative Example 3 is a comparative example corresponding to Experimental Examples 6 to 8 and is made of polyvinylidene fluoride, but the storage spring constant under the above conditions is set to 69 kg / cm. Comparative Example 4 is a natural gut, and the storage spring constant under the above conditions is 123 kg / cm.

[0027]

[Table 2]

In this experiment, the resilience, controllability, shot feeling, and hold feeling of the above Experimental Examples 1 to 8 and Comparative Examples 1 to 4 were examined by a feeling test. Also, the durability was tested.

In the above-mentioned feeling test of resilience,
The guts of each experimental example and comparative example were racketed (DP80 International Tour over MID SIZE made by DUNLOP) with a warp yarn of 27 kg (60 lb) and a weft yarn of 21.6 kg (48 l).
It was stretched in b), 108 amateur players actually hit the ball, and the number of people who answered "good" with respect to resilience was counted.

On the other hand, the durability was measured by the above racket (DUNLOP DP80 International Tour over
27 kg (60 lb) warp and 21 weft for MID SIZE)
Gut is stretched with a tension of 6 kg (48 lb), and 50 m /
It was checked whether or not the gut was cut by hitting a hard tennis ball at a speed of sec 1500 times.

Table 3 below shows the results of the above-mentioned feeling test and durability measurement. In the table, in the column of resilience to durability, ⊚ indicates that more than 90 out of 108 people answered “good”, ○: 70 to 89 out of 108 answered “good”, Δ: 50 to 69 out of 108 answered “good”, ×: less than 50 out of 108 answered “good” It shows the case. In Table 3, in the column of durability, ○
Indicates that the gut was not cut by 1500 times, and x indicates that it was cut by 1500 times.

[0032]

[Table 3]

In Table 3 above, when comparing Experimental Example 1 to Experimental Example 4 and Comparative Example 1 which are both made of nylon 66, Experimental Example 1 to Experimental Example 4 are repulsive, controllable, hit feeling, and hold feeling. Peach is good, while Comparative Example 1
Is inferior to Experimental Examples 1 to 4 in resilience and hold feeling. From this, it can be confirmed that in Experimental Examples 1 to 4, since the storage spring constant is set in the range of 80 to 190 kg / cm, the resilience and the like are good.

Experimental Example 5 in which both are made of nylon 6
When Comparative Example 2 is compared with Comparative Example 2, the resilience, controllability, shot feeling, and hold feeling are all good in Comparative Example 2, while Comparative Example 2 is poor in resilience, hit feeling, and hold feeling. From this, in Experimental Example 5, the storage spring constant is 80 to 19
Since it is set in the range of 0 kg / cm, it can be confirmed that the resilience is good.

Further, when comparing Experimental Examples 6 to 8 and Comparative Example 3 which are both made of polyvinylidene fluoride, Experimental Examples 6 to 8 show repulsion, controllability, shot feeling, and hold feeling. Comparative Example 3 is inferior in controllability and shot feeling. From this, it can be confirmed that in Experimental Example 5, the storage spring constant is set in the range of 80 to 190 kg / cm, and thus the resilience and the like are good.

The natural gut was cut before it was hit 1500 times, whereas the guts of Experimental Examples 1 to 8 according to the present invention were not cut up to 1500 times, and thus the durability was high. It can be confirmed that it is good.

[0037]

As is apparent from the above description, the synthetic fiber test racket gut according to the present invention has a sample amplitude of 40 mm and an initial load of 27 kg.
The storage spring constant when a sine wave distortion of 5% and a frequency of 10 Hz is applied is set to 80 to 190 kg / cm, and the elastic properties of the natural gut under conditions similar to those of a ball hitting a racket are set. Since the characteristics are set close to, good resilience, controllability, shot feeling, and hold feeling can be obtained.

Further, since the gut according to the present invention is made of synthetic fiber such as polyamide resin, polyvinylidene fluoride resin, etc., it has good durability and water resistance and is cheaper than natural gut. .

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a storage spring constant.

3 (A), (B) and (C) are sample lengths,
It is a schematic diagram for explaining an initial load and one side amplitude.

[Explanation of symbols]

 1 gut 2 fibers

Claims (1)

[Claims] 1. A sample length of 40 mm and an initial load of 27 kg.
Gut for a tennis racket made of a synthetic fiber, which has a storage spring constant of 80 to 190 kg / cm when a sine wave distortion having a one-sided amplitude of 1.5% and a frequency of 10 Hz is applied in the above state.