JP2856325B2 - Wood club head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a crag head called a wood club in a golf club.

[Conventional technology]

The face (hitting surface) of the head of the wood club is formed by a convex curved surface. This curved surface is formed by a bulge having a horizontal radius of curvature (bulge radius) and a roll having a vertical radius of curvature (roll radius). Therefore, the normal direction at each point of the face is different. A face center for realizing an ideal shot is provided in the face. The shape of the bulge is related to the launch angle, the initial velocity and the side spin of the ball, and has a direct influence on the left-right deflection of the ball drop point. The shape of the roll is related to the vertical launch angle, initial velocity, and backspin of the ball, and has a direct effect on the vertical deflection in the vertical plane including the trajectory of the ball. The bulge radius and roll radius have traditionally been 254 mm (10 inches). Considering only the gear effect, when the ball B comes off the face center C (see FIG. 2) and hits the face of the head 1, as shown in FIG. Backspin is applied when hitting the bottom of the. The amount of such a spin is greater as the center of gravity of the head 1 is deeper. The larger the loft angle L of the head 1 (see FIG. 2), the stronger the backspin. Therefore, in a wood club head having a deep center of gravity, the loft at the upper part of the face is increased in order to alleviate the top spin caused by the gear effect generated when the ball B hits the top, and the back effect is caused by the gear effect generated when the ball B hits the lower part. It is thought to reduce the lower loft to reduce spin, and if it is changed continuously, the roll radius will be 254 mm
It became.

[Problems to be solved by the invention]

If the head of the wood club is made of persimmon, the center of gravity is deep, so the roll radius is 254m as described above.
m is optimal, but when the head is formed of a metal material, the center of gravity of the metal head is about 30% shallower than that of the persimmon head, and the center face C
When the ball hit the upper part, the top spin due to the gear effect could not be obtained, and when the ball hit the lower part, the back spin due to the sufficient gear effect could not be obtained, and the ball could not be raised. In the graph shown in FIG. 4, I indicates the amount of spin at each hit point of a persimmon head having both a roll radius and a bulge radius of 254 mm, and II indicates the amount of spin at each hit point of a metal head having a similar bulge radius and roll radius. It is a graph which shows the amount of spin. The loft angle was 12 ° for both I and II, and a hitting robot made a test hit at a head speed of 34.5m / s. As is clear from the graph shown in FIG. 4, the spin amount at the point below the face center C in the metal head is smaller than that of the persimmon.

By the way, when an amateur golfer hits below the face center and uses a metal head, the ball does not go up because the amount of backspin is small as shown by the symbol II in the graph of FIG. The distance also drops.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a wood club head which can raise a ball even if a hit point is lower than a face center in a metal head having a shallow center of gravity.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a wood club head formed of a metal material having a face surface that is a convex curved surface and a center of gravity depth of 25 mm or less, wherein a roll radius is set to 400 mm or more. is there. Further, in a wood club head made of a metal material having a convex curved surface and a center of gravity depth of 25 mm or less, the roll radius is set to 400 mm or more and 610 mm or less.

[Action]

An actual hitting test was carried out on a head having a roll radius of 508 mm, a bulge radius of 254 mm and a depth of the center of gravity of 23 mm as in the prior art.
As shown in the figure, the ball hitting the lower part of the face center was also back-spinned, and the ball rose high. Assuming a roll radius of 508 mm, the loft angle was actually 10.9 ° when the ball was hit 10 mm below the face center. If the ball is hit 10 mm below the face center with a head having a roll radius of 254 mm, the actual loft angle at the hit point is 9.75 °, and a difference of 1.15 ° in the loft angle is recognized. Therefore, when the ball is hit 10 mm below the face center, a head having a roll radius of 508 mm has an effect of increasing both the launch angle and the backspin, and raising the ball.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the horizontal direction of the radius of curvature at the face surface 2 of the head 1 wood club formed from metal material (bulge radius) R ₁ was 254mm as in the conventional. Then, the second bulge of the face 2, as shown in FIG. And vertical curvature radius (roll radius) R ₂ and 400mm or more. The depth of the center of gravity of the head 1 was 25 mm or less.

The head 1 is formed from a metal material, and the roll radius is 508 m
The result of an actual hitting test using a wood club head having a center of gravity of 23 mm and a depth of the center of gravity of 23 mm was as shown by reference numeral III in FIG. Both the loft angle and the head speed of the head indicated by reference numeral III were the same as those of reference numerals I and II.

The curve indicated by the symbol I in FIG. 4 shows the optimum amount of backspin in the persimmon head, and it is effective for the metal head to make the curve I as close as possible to increasing the flight distance. In other words, a backspin amount larger than the curve I may become excessive and reduce the flight distance. Focusing on the portion below the face center, it can be seen that curve II (roll radius 254 mm) in FIG. 4 is too far from curve I and curve III (roll radius 508 mm) is quite close to curve I. To show this in a graph, a straight line was drawn parallel to the horizontal axis at each of the hit points (−2 mm, −3 mm, −4 mm,...) Below the face center in FIG. 254mm), III
(Roll radius 508 mm), the backspin amount at the point where I intersects is read, and then the backspin amount and the roll radius are plotted on the abscissa and the backspin amount on the curves II and III, respectively. When the graph is drawn, it becomes as shown in FIG. Further, in the graph of “backspin amount and roll radius”, the roll radius for obtaining the backspin amount at the time of curve I in the straight line of each hit point is approximately 610 mm.
Becomes Therefore, roll radius is 610m with metal head
It can be said that m or less is preferable.

〔effect〕

As described above, according to the present invention, the face surface is a convex curved surface, and the center of gravity of the wood club head formed of a metal material having a depth of 25 mm or less has a roll radius of 400 mm or more. Even when hitting the ball with the face center removed, the spin rate increases, especially when hitting the ball at the bottom, the back spin and launch angle both increase, which has the effect of raising the ball and improving the flight distance Can be. In addition, according to the invention in which the roll radius is 400 mm or more and 610 mm or less, according to the invention, the face surface is a convex curved surface and the center of gravity of the wood club head formed of a metal material having a center of gravity depth of 25 mm or less hits at the lower part of the face. The flight distance of the ball can be increased.

[Brief description of the drawings]

FIG. 1 is a plan view of the head as viewed from above, FIG. 2 is a side view of the head for explaining the roll radius, and FIG. 3 is a diagram showing how spin is applied when a hit point is removed from the face center. FIG. 4 is a graph showing the results of experiments on the spin amount due to the difference in the hitting point between the persimmon head and the metal head having a roll radius of 254 mm and the metal head of the embodiment of the present invention, and FIG. It is a graph which shows the relationship of a roll radius. 1 ... head, 2 ... face, R ₂ ... roll radius.

Claims (2)

(57) [Claims] 1. A wood club head formed of a metal material having a convex curved surface and a center of gravity depth of 25 mm or less, wherein the roll radius is set to 400 mm or more. . 2. A wood club head having a convex curved surface and a metal club having a center of gravity depth of 25 mm or less, wherein a roll radius is 400 mm or more and 610 mm or less. Head.