JPH11347161A - Iron golf club head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a carry without the possibility of increasing the energy loss of a ball. SOLUTION: This iron golf club head is formed to <10,000 Hz in the natural frequency corresponding to the peak value of the fifth order or sixth order of a transmission function after the vibration mode transmitted to a shaft side by the impact received at the clubface 2 of the club head is subjected to a mode analysis. In addition, the value of the eigenfrequency corresponding to the peak value of the first order of the transmission function is set within a range of 2,700 to 3,600 Hz.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head structure of an iron golf club, and more particularly to a head structure of a long iron or a middle iron having a long flight distance.

[0002]

2. Description of the Related Art In recent years, in the design of long irons and middle iron clubs, there has been a tendency to further increase the flight distance. For example, the length of a shaft is increased by about half an inch, and the loft angle is reduced by several degrees. In order to increase the repulsive force to the ball, means for increasing the material hardness of the face surface is employed.

[0003]

However, these means have a feeling that they are already extremely tight, and the limit of the future is becoming apparent. In particular, the material hardness of the face surface is increased so that a large repulsive force is applied to the ball when hitting. It has been a problem that giving the ink may increase the energy loss of the ball and reduce the flight distance of the ball.

[0004] In the iron club head according to the present invention,
In view of such circumstances, it is an object of the present invention to provide an iron golf club head that can increase the flight distance of a ball without fear of increasing the energy loss of the ball.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention modulates the vibration transmitted to the shaft side by the impact received on the face surface of the club head, and determines the fifth or sixth order of the transfer function. The natural frequency corresponding to the next peak value is less than 10000 Hz, and the natural frequency corresponding to the first peak value of the transfer function is brought close to the natural frequency, and the value of the first natural frequency is in the range of 2700 to 3600 Hz. It is set within.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of an iron club head (5 irons: # 5) according to the present invention.
It is sectional drawing in an inner sweet spot. As the face member 1, a member having a lower rigidity than the head main body 3 and a large internal loss (that is, a hysteresis loss) is selected to reduce the fifth or sixth natural frequency. In the present embodiment, such a face member 1 is made of pure titanium and has a shape different from that of the head main body 3 and a circular or elliptical concave portion 4 is formed on the back surface of the face surface 2. . The head body 3 is made of beryllium copper and has a through hole 5 in which the face member 1 is fitted in a hollow portion. The face member 1 has a minimum thickness of 2 mm at the center and a thickness of 3 mm at the periphery. Reference numeral 6 denotes a hosel into which the shaft is inserted and fixed.

FIGS. 2 and 3 show a vibration mode analysis of a comparative example (the fifth iron head having the same shape as the embodiment except that the entire head integral with the face member is made of stainless steel and there is no recess on the back of the face) and the embodiment. Are compared. In the vibration mode analysis, the whole area on the face 2 was subdivided into 30 cells, and each cell was hit (input) with a small hammer, and the vibration output was detected by an accelerometer attached to the hosel base. Analyzer (Ono Sokki Co., Ltd.) and mode analyzer (analysis software, VIBLAN
T) is a frequency analysis of the vibration mode of the face surface. The vertical axis in FIGS. 2 and 3 shows a so-called transfer function obtained by dividing the output by the input, and the horizontal axis shows frequency (frequency, Hz).

2 and 3, in the comparative example of the conventional product,
The natural frequency corresponding to the first order peak of the transfer function is 270
0 Hz, and the natural frequency corresponding to the fifth peak of the transfer function is 10500 Hz. In the embodiment, the first natural frequency is 3100 Hz, and the fifth natural frequency is 8250 Hz. Is shown. As a result, in the head of the embodiment, the deformation of the core of the ball at the time of impact is small, the energy loss is reduced, and the flight distance of the ball is increased. In addition, since the primary natural frequency is an appropriate value of 3000 Hz, the feel is excellent. That is, a responsive, firm hit feeling could be obtained.

In the present invention, various iron club heads are used to respond to a shock input to the face surface 2.
The vibration output of one end portion (usually the hosel 6) of the head into which the tip of the shaft is inserted is measured, and the mode analysis of the natural frequency of the head is performed. In each of the clubs, about 5 to 6 remarkable output peaks are present, and of these peaks, the primary natural frequency (the lowest frequency at which the output peak appears) is determined by the overall club head. It has been found that the stiffness is particularly related to the stiffness, while the stiffness of the face member 1 is most closely related to the fifth or sixth natural frequency. In addition, it has been found that the first natural frequency is greatly related to a hit feeling felt by a player at the time of shooting a ball. However, when the fifth- or sixth-order natural frequency is set to 10,000 Hz or less to approach the first-order natural frequency, the first-order natural frequency itself changes at the same time to a small value. It also turned out to be worse. Note that the first natural frequency is 2
When the frequency is less than 700 Hz, the shot feel becomes unreliable at the time of a shot. On the other hand, when the frequency exceeds 3600 Hz, the ball is released too early due to a hard feel, and there is a concern that the directionality of the hit ball may be reduced.

FIGS. 4 and 5 show another embodiment according to the present invention, in which a projection 7 is provided on the back surface of a face surface 2 serving as a hitting surface without contacting a head body 3. FIG. I have. The projection 7 may be formed integrally with the face member 1 or may be attached to the face member 1 as a weight separately from the face member 1. When the weight is used, the material is preferably one having a large specific gravity (7 or more). With such a projection 7, the natural frequency corresponding to the fifth or sixth order peak value is effectively reduced without substantially changing the natural frequency corresponding to the first order peak value. Can be.

[0012]

As described above, according to the present invention,
The vibration transmitted to the shaft side due to the impact received on the face surface of the club head is subjected to modal analysis, and the natural frequency corresponding to the fifth or sixth peak value of the transfer function is 10,000H.
z, and the value of the natural frequency corresponding to the first-order peak value of the transfer function is set in the range of 2700 to 3600 Hz. Therefore, the rigidity of the face member decreases and approaches the rigidity of the entire club. It does not apply an extreme impact force (repulsive force) to the ball when hitting on the face surface, so that the energy loss due to the deformation of the ball (especially the deformation of the core) can be reduced, and the flight distance of the ball Increase. Further, in the present invention, the first natural frequency is 2
Under conditions maintained in the range of 700-3600 Hz,
As described above, since the value of the fifth or sixth natural frequency is displaced small, it is possible to increase the flight distance of the ball while maintaining a good hit feeling.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a preferred embodiment of the present invention.

FIG. 2 is a graph showing a vibration mode analysis result of a comparative example.

FIG. 3 is a graph showing a vibration mode analysis result of the example.

FIG. 4 is a sectional view showing another embodiment.

FIG. 5 is a rear view of the embodiment of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Face member 2 Face surface 3 Head body

Claims (1)

[Claims] 1. A mode analysis of vibration transmitted to a shaft side by an impact received on a face surface of a club head, wherein a natural frequency corresponding to a fifth or sixth peak value of a transfer function is set to less than 10,000 Hz, Also, the value of the natural frequency corresponding to the primary peak value of the transfer function is 2700 to 3600
An iron golf club head set in the range of Hz.