JPH0456630B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a ball hitting tool for sports. Generally speaking, using a golf club as an example of a ball hitting tool, the action of the golf club for hitting a golf ball can be summarized as follows. In other words, influence on trajectory...effect on spin, launch angle, and directionality; influence on ball initial velocity...effect on head speed; influence on repulsion coefficient; It is explained mechanically, focusing on the moment of inertia of Also, head speed is explained with a focus on shaft in relation to swing. Conventionally, it has been said that by making the natural frequencies of this shaft the same within a club set or creating a certain difference, effects such as ``easiness of swinging'' and ``swinging with the same rhythm'' have been cited, but theoretically, The current situation is that it has not been clarified. In particular, the issue of the coefficient of repulsion is an issue between the golf ball and the golf club, and the influence of the club (head) on the coefficient of repulsion during collision (hitting) has not been clear until now. It had not been done. By the way, the constituent materials of conventional golf clubs include Versimmon (persimmon wood), ABS resin, carbon fiber reinforced resin (hereinafter sometimes abbreviated as CFRP),
Aluminum, stainless steel, etc. have been used. Conventionally, it has been said that the harder the material, the better the repulsion from the golf ball and the higher the initial velocity of the ball. Blue Damo compressed material is used instead of Versimon,
Furthermore, carbon fiber reinforced resin (CFRP) is required to have a high fiber content, and has traditionally been thought to have a high repulsion coefficient because it is hard. The present invention breaks this conventional wisdom, and as a result of repeated numerous experiments over many years, we have found the optimal hardness to maximize the rebound and initial velocity of the ball. It was found that if the optimum hardness was exceeded, the repulsion deteriorated. They went further and discovered that the mechanical impedance of the ball and ball hitting tool was involved. SUMMARY OF THE INVENTION An object of the present invention is to provide a ball hitting tool that increases the coefficient of repulsion when hitting a ball and brings the initial velocity of the ball closer to its maximum. Therefore, a feature of the present invention is that the mechanical impedance of the hitting part shows a minimum value in a frequency region near the frequency where the mechanical impedance of the object to be hit shows a minimum value. It lies in the fact that it constitutes the whole. Hereinafter, the present invention will be described in detail based on illustrated embodiments. First, to explain the mechanical impedance of a mechanical system, it is defined as "the ratio of the response of a force acting on a certain point to the response of another point." That is,
When input is F and response speed is V, mechanical impedance Z is defined as Z=F/V. FIG. 3 is a diagram illustrating how the mechanical impedance of a general golf ball changes, with the vertical axis representing the absolute value of the mechanical impedance Z and the horizontal axis representing the frequency. The measurement was performed using a frequency analyzer (FFT analyzer) known in the field of mechanical vibration. (For example, the model 5420A made by Yokogawa Huuretsu Packer Co., Ltd. is used.) In this figure, 2 to 5 minimum values P in the frequency range 0 to 10,000 hertz (Hz) are used. It can be seen that the golf ball has... Furthermore, the first minimum value P is at a frequency N of approximately 3000 hertz. The frequency that shows this minimum value P... is the so-called natural frequency, and the mass of the structure (ball) -
This is determined by the spring system. On the other hand, FIG. 1 or 2 shows a wood-shaped golf club as an example of a ball-hitting tool with a diameter of 0 to about 12,000.
The results of measuring mechanical impedance in the Hertz frequency domain are shown. However, the mechanical impedance (vertical axis) is calculated by taking the absolute value as a logarithm.
Shown as a value multiplied by 20. Virtual line 1 shows a conventional example, and all existing wood-type golf clubs (including those called carbon heads and metal heads) operate in the frequency range 0 to 0.
No clear minimum value appears within 10,000 Hz. Specifically, in the ball hitting tool according to the present invention, the mechanical impedance Z of the portion of the entire golf club head that directly hits the ball is the curves C, D, and E in FIG. 1 or the solid line 2 in FIG. As shown by broken line 3, in the frequency range of 0 to 10,000 hertz,
The mass distribution, spring constant, and damping coefficient of the club head, shaft, etc. are set so as to have one or more local minimum values P. To explain the embodiment more specifically, in FIG. 4, the center point 5 of the face surface 4 where the ball is hit is
Consider a dividing line a-b perpendicular to the face surface 4, passing through points Qa and Qb that divide this line a-b into three equal parts, and connecting the club head 6 with straight lines La and Lb perpendicular to the line a-b. If divided into three parts, the center of gravity G of the club head 6
is near the straight line La. That is, the center of gravity G is located approximately 1/3 from the face surface 4, and the ratio of the masses of the three parts is M ₁ :M ₂ :M ₃ =5:3:2. (This mass ratio remains approximately the same as that of the conventional club head.) As shown in FIG. 5, the insert 7 of the face 4 is made of a material with a spring constant k that is significantly smaller than that of the conventional club head. For example, the spring constant k
Insert 7 with ≒8000 to 20000Kg/cm, thickness T≒8mm, width W≒40mm, and height H≒40mm
If you use , the minimum value P will appear in the frequency range 0 to 10000 Hz. Preferably, the minimum value P appears in the frequency range of 1500 to 8000 hertz. Particularly preferable is 2000 to 6000 (judging from the ball initial velocity described below)
The goal is to make the minimum value P appear in the frequency range of 2,500 to 4,000 hertz, considering its compatibility with a general golf ball with the characteristics shown in Figure 3. It can be said that it is optimal to do so. In this way, the spring constant k of the material of the insert 7
By making P sufficiently smaller than the spring constant of conventional ABS resin, carbon fiber reinforced resin laminates, or metal plates such as aluminum, the minimum value P can be reduced to 1 at a predetermined frequency between 0 and 10,000 hertz. ~ Several clubs are obtained. In particular, this has the advantage that the mass distribution and shape of the conventional golf club can be maintained as they are.

[Table] Shown.
However, conventional examples A and B and embodiment C of the present invention
Explanations of the types of golf clubs D and E and the actual measurement results (average values of many measurements) are shown in Figure 1 and (Table -
Shown in 1). (The ball used was a two-piece ball with an ionomer resin cover.) The following can be seen from Table 1 and FIG. Conventional example A uses ABS for the persimmon head base material.
The resin insert is installed as shown in Figure 5, but there is no minimum value P within the frequency range of 0 to 10,000 Hz.
does not indicate. However, with a spring constant of 80000Kg/cm
Conventional example B, in which a CFRP insert is attached to a carbon head base material, shows a minimum value when the frequency exceeds 10,000 Hz. Even if it showed a minimum value at a frequency exceeding 10,000 Hz, the ball initial velocity of Conventional Example B was equivalent to or slightly worse than that of Conventional Example A. On the other hand, Examples C, D, and E of the present invention are ionomer resins with spring constants K of 20000, 10000, and 8000 Kg/cm, respectively, and frequencies of 7200, 5250, and 8000 Kg/cm, respectively.
The minimum value P is clearly shown at 3800Hz, and when the head speed is constant at 45m/sec for each club,
Comparing the initial velocity Vb of each ball with conventional example A,
Example C=0.46m/sec increase, Example D=0.71m/sec
sec increase, Example E = 1.98 m/sec increase.
This corresponds to an increase in the carry of a golf ball of 2 to 8 m. (A significant increase in carry was confirmed.) Next, Figure 2 and (Table 2) show other actual measurement results. The conventional example is shown by virtual line 1, but no minimum value appears. This is the carbon head base material.
It is equipped with an ABS resin insert.
In this experiment, two types of balls were measured.

[Table] This (Table 2) also shows that the ball initial velocity of the embodiments of the present invention (solid line 2 and broken line 3) is higher than that of the conventional example (phantom line 1). In addition, from a large number of actual measurement results, if the value of mechanical impedance Z at the minimum value P is 5 decibels (dB) or more smaller than the mechanical impedance Z at the nearby frequency,
It can be said that the increase in the initial ball speed mentioned above is remarkable. Note that mechanical impedance is influenced by the mass distribution of the object, the spring _constant , and _the damping coefficient. Or, by changing various materials and structures, the frequency range from 0 to
It is also possible to construct the entire golf club so that it exhibits a minimum value within 10,000 hertz. Also,
It is also possible to use engineering plastic such as polycarbonate as the insert 7 and adjust the spring constant so that it exhibits a similar minimum value P. In addition, in the above-described embodiment, the golf club as a whole is configured such that the minimum value appears in a predetermined frequency range in the mechanical impedance of the face surface that directly hits the ball, but in addition to this,
Regarding only the main hitting part, that is, the club head 6,
It is also desirable to design such that the mechanical impedance of the face exhibits a minimum value in a predetermined frequency range. Furthermore, Fig. 6 shows a ball hitting tool,
In addition to the golf club 8, examples include a tennis racket 9, a baseball bat 10, or a table tennis racket 11, and for any of these hitting tools,
Find the frequency at which the mechanical impedance of a tennis ball, baseball ball, or ping pong ball shows a minimum value, respectively, and then calculate the mass distribution, spring constant, etc. so that the mechanical impedance of the hit object shows a minimum value in a frequency region near the minimum value. By appropriately setting the material, shape, structure, etc., the initial velocity of the ball will increase and the flight distance will be extended. The present invention is thus widely applicable to various sports ball hitting tools. In the embodiment of the golf club of the present invention, the main hitting part or the entire golf club is configured such that the mechanical impedance of the part that directly hits the golf ball shows a minimum value in the frequency range of 0 to 10,000 Hz. Therefore, regardless of whether the hardness of the part that directly hits the ball is not high,
(Breaking conventional wisdom) The rebound of the ball is large,
The ball's initial velocity can be increased, and flight distance can be increased. This is a golf club that is skillfully adjusted to match the mechanical impedance characteristics of the ball. As described in detail above, the present invention is directed to the main part of the hitting part or the hitting part so that the mechanical impedance of the hitting part shows a minimum value in a frequency region near the frequency where the mechanical impedance of the object to be hit shows the minimum value. Since it is a ball hitting tool that consists of a whole, it is the best combination with the object being hit (ball, etc.).
Maximum repulsion can be obtained and the flying distance of the object being hit can be increased.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 show different actual measurement results, and are diagrams of mechanical impedance characteristic curves comparing the example of the ball hitting tool according to the present invention and the conventional example;
Fig. 3 is a diagram of the mechanical impedance characteristic curve of the ball, Fig. 4 is a schematic plan view for explaining the configuration, Fig. 5 is a perspective view showing one embodiment of the present invention, and Fig. 6 is a diagram of various ball hitting tools. FIG. 3 is a diagram showing a specific example. 7...Insert, Z...Mechanical impedance, P...Minimum value, N...Frequency.

Claims (1)

[Scope of Claims] 1. The main part of the hitting part or the entire hitting part is configured so that the mechanical impedance of the hitting part shows a minimum value in a frequency region near the frequency where the mechanical impedance of the object to be hit shows the minimum value. A striking tool characterized by: 2. The ball hitting tool according to claim 1, wherein the main part or the entire hitting part is configured such that the mechanical impedance of the part that directly hits the ball shows a minimum value in the frequency range of 0 to 10,000 hertz. 3. The ball hitting tool according to claim 1, wherein the frequency range showing the minimum value is 1,500 to 8,000 hertz. 4. The ball hitting tool according to claim 1, wherein the frequency range showing the minimum value is 2000 to 6000 hertz.