JP2001334004A - Golf club head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a golf club head which restricts possible loss in flying range when off-center hitting occurs by improving the strength of a face without increasing the weight of the head. SOLUTION: In the hollow-structured golf club head with a loft of 5-30 deg., a plurality of protruded ribs are arranged in an areas from the heel side to the toe side on the back of a face of the head. The secondary moment in the cross section of at least one of protruded ribs is changed in the longitudinal direction of the rib.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a face rear surface of a golf club for a medium to long distance having a relatively small loft angle.

[0002]

2. Description of the Related Art A golf club head is made of a metal material having a low specific gravity and a high strength, and the size of the head is increasing year by year. Therefore, the area of the face is enlarged, and the thickness of the head is reduced in order to suppress the total weight of the head. On the other hand, in order to further increase the flight distance, recently, it has become important to utilize the repulsion force by increasing the deflection of the face when hitting a ball. As a result, there is a concern that the strength of the face may be reduced. As a means for compensating for this, it has been proposed to provide a plurality of reinforcing ribs on the central portion of the back face or on the entire back face.

[0003]

However, in such a conventional proposal of rib reinforcement, it is possible to increase the strength of a face having a large area while suppressing the weight increase as much as possible. Although it was possible to increase the flight distance by increasing the size of the face and reducing the thickness of the face, on the other hand, considering the case where the ball hit the center of the face, that is, the case where the ball was hit off-center, a large flight distance still remained. The problem that distance loss occurs remains. In particular, looking at the distribution of the deflection of the face at the time of hitting, when an off-center hit is made, the deflection of the face and hence the repulsive force of the face are sharply reduced, and the flight distance is significantly reduced.

Further, in the golf club proposed in the prior art, since an excessive number of ribs are arranged, the weight of the face is increased, so-called a center of gravity design of the head (the weight of each part of the head is appropriately proportionally divided). There is a problem that the degree of freedom of the design for changing the position of the center of gravity of the head is reduced. Therefore,
In view of such circumstances, the purpose of the present invention is to:
An object of the present invention is to provide a golf club head which reinforces a thin face without increasing the head weight and effectively prevents loss of flight distance when hit off center.

[0005]

In order to achieve the above object, a golf club head according to the present invention has the following features.
A golf club head having a hollow structure having a loft angle of 5 to 30 °, wherein a plurality of convex ribs are arranged in a region from a heel side to a toe side of a back surface of the face of the head; The secondary moment of area of at least one of the convex ribs is variable in the longitudinal direction of the rib.

According to the inventor's detailed experimental results, no matter where the face is hit, the face undergoes vertical deflection on the face, which has a maximum value around the centroid of the face. In particular, in the conventional product, the area of the maximum value of the bending is narrow, and the bending distribution from the toe to the heel direction has a mountain-shaped distribution form with the centroid at the top. Therefore, in the conventional product, when a hit is made at a position on the face surface deviating from the centroid (in the present invention, such a case is referred to as an off-center hit, ie, an off-center hit of the face). Is hit at the foot of the mountain-shaped deflection distribution, resulting in a small deflection, that is, a small repulsive force, resulting in a large flight distance loss.

On the other hand, in the golf club head according to the present invention, as described above, at least one of the plurality of ribs provided in the region from the heel side to the toe side on the back surface of the face has a longitudinal direction. Since the second moment of area of the rib is changed to an appropriate value everywhere, the bending rigidity of the face is adjusted in conjunction with the appropriate arrangement of the rib, and the shape of the distribution of the deflection of the face at the time of hitting the ball is changed. The maximum value area can be set to have a broad broad distribution from the toe side to the heel side of the face, and the area of maximum deflection is somewhat biased toward the toe side or the heel side. Therefore, even in the case of the off-center hit where the hit point deviates from the center of gravity, it is possible to obtain a large deflection and thus a large repulsive force, thereby suppressing a flight distance loss to be small. It can be.

Further, by appropriately arranging a plurality of ribs on the back surface of the face, even when the face is large and thin, excessive deformation of the face is prevented, and the durability of the face is improved. In addition, since the strip-shaped ribs are arranged only at necessary places on the face, the weight can be prevented from increasing unnecessarily and the head weight can be prevented from increasing.

The magnitude of the second moment of area of the rib is 15 mm ⁴ to 2 × 10 ^-3.
mm ⁴ , more preferably 10 mm ^{4 to} 5 × 10 ^−3.
It is preferable to set the range of mm ⁴ . If the magnitude of the second moment of area exceeds 15 mm ⁴ , there is a concern that the weight of the face becomes excessive and the degree of freedom in designing the center of gravity of the head is reduced, and the second moment of area is 2 × 10 ⁻³ mm ⁴
If the size is smaller than the above range, the effect of varying the second moment of area cannot be sufficiently obtained.

In the present invention, the second moment of area of the rib is a moment about an axis parallel to the face surface passing through the centroid of the rib cross section. In the present invention, the centroid is defined in a general textbook of material mechanics, and a value obtained by dividing the first moment of area (I) with respect to an arbitrary axis by the total area (A) is calculated from the axis. The distance (e) to the centroid is obtained using the following equation. e = I / A, where I = ∫ydA, y is the distance from the axis to the minute area dA.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the cross-sectional shape of a rib provided on the back of a face can be various shapes such as a rectangular shape, a semicircular shape, and a triangular shape. The arrangement of the ribs on the back face of the face is desirably an annular shape centered on the centroid of the face. Note that when arranging a plurality of large and small annular ribs in a multi-ring shape, it is not necessary to arrange them completely concentrically, and the centers of the individual ribs can be shifted. In addition, it is desirable that the ribs be continuous in the longitudinal direction from the viewpoint of manufacturing easiness. Further, the material of the rib is desirably the same as that of the face, but a material different from that of the face can be adopted.
It should be noted that the club head to which the present invention is applied is a club head that requires a long-distance flying distance, and the loft angle is generally set in the range of 5 to 30 °. Empirically, it has been found that when the angle is less than 5 °, the face surface is in a standing position and it is extremely difficult to hit, and when the angle exceeds 30 °, the flight distance is significantly reduced.

Embodiment An embodiment according to the present invention will be described below with reference to FIGS. FIG. 1 shows that the volume of a hollow head made of a titanium alloy is 280.
cc (0.28 liter), face area 32.6c
FIG. 9 is a rear view of the face of the driver club head having m ² , an average thickness of the face of 2.5 mm, and a loft angle of 11 °.

In FIG. 1, three large, medium, and small convex annular ribs 3 made of the same material as the face 1, that is, a titanium alloy, are concentrically formed on the back surface 2 of the face 1 with the centroid (C) of the face 1 as the center. Are located in As shown in the AA sectional views of FIGS. 1 and 2, the small annular ribs 3a have the same rib width of 3 mm over the entire circumference and the same rib height of 1 mm.
mm. Therefore, the second moment of area of the rib 3a in the cross-sectional view is set to 2.25 mm ⁴ .

Further, in the middle-sized annular rib 3b, the rib width and the rib height are 1.5
mm and 1 mm, and the second moment of area in the above sectional view is set to 0.2813 mm ⁴ . On the other hand, on the toe 5 side, the rib width
The section 2 is enlarged to 5 mm, which is approximately 3.3 times the side, and the rib height is set to a slightly larger value of 1.4 mm.
Next moment is 14.58mm, almost 52 times the heel 4 side
It has been increased to ^four .

Further, in the outermost large-sized annular rib 3c, the secondary moment of area is changed in three stages along the longitudinal direction of the rib. That is, on the heel 4 side of the annular rib 3c, the rib width is set to 0.4 mm and the rib height is set to 1 mm, and the secondary moment of area is set to 0.0053 mm ^4. Side and the leading edge 7 side,
The rib width is set to 1 mm, the rib height is set to 1 mm, the secondary moment of area is 0.083 mm ^4, and the heel 4
The value is set to approximately 15 times the value on the side. Further, on the toe 5 side of the annular rib 3c, the rib width is 2 mm and the rib height is 1 m.
m, and the second moment of area is 0.667 mm
^The value is set to the largest value in the longitudinal direction of the annular rib 3c, which is about 125 times that of the side ⁴ and the heel 4 side.

In the golf club head of this embodiment, the three annular ribs 3a, 3b, 3c are arranged on the back surface 2 of the face 1 as described above. Since the overall second moment of area increases, the deflection of the face when the ball is hit on the face (bending in the direction perpendicular to the face that becomes the hitting surface) decreases on the toe 5 side and increases on the heel 4 side. Therefore, the shape of the face deflection distribution changes from the conventional chevron shape to a trapezoidal shape. That is, the area where the maximum value of the deflection is obtained is enlarged from the toe side to the heel side (see the deflection distribution of the face in the club head of the embodiment shown in FIG. 3).

[0017] As a result, even when the face is hit off-center, that is, off-center hit, which is frequently caused by an average golfer of general skill, a large face deflection occurs and a large repulsive force is obtained. In such a case, the flying distance loss can be suppressed to a minimum.

Further, since the maximum value of the deflection of the face is not concentrated near the centroid of the face unlike the conventional product, the energy due to the impact is distributed over a wide range of the face, and the durability of the face is improved. Therefore, it is not necessary to provide an excessive number of ribs when the face is made thinner, and it is possible to suppress an increase in head weight.

In order to clarify the effects of the present invention,
A conventional product in which two annular ribs 30a and 30b are concentrically arranged on the back surface 20 of the face 10 is shown in the rear view of FIG. 4 as a comparative example. In this comparative example, the cross-sectional shape of all the annular ribs (30a, 30b) is the same over the entire circumference in the longitudinal direction. That is, they have the same rib width and rib height. As a result, as shown in FIG. 5, the distribution of the deflection of the face is such that the area where the deflection is maximum has a narrow mountain shape, and when the off-center hit is performed, the deflection of the face is small and the repulsive force is small. As a result, the loss of the flight distance increases.

In the above embodiment, the ribs are formed in an annular shape. However, for the purpose of the present invention, the present invention is not limited to this. For example, the ribs may be arranged in a form as shown in FIG. I can do it.

[0021]

In the golf club head according to the present invention, a plurality of convex ribs are provided in a region from the heel side to the toe side on the back of the face, and the value of the second moment of area of the rib in the longitudinal direction of the rib is provided. Is changed, the distribution of the deflection of the face generated at the time of impact becomes trapezoidal, and the area where the maximum value of the deflection of the face exists can be expanded from the toe side to the heel side. When the ball is hit, a large deflection of the face and thus a large repulsive force can be obtained, so that the loss of flight distance, which is a problem in the conventional product, can be remarkably suppressed. Therefore, the so-called sweet area (for example, the area of the face surface where the flight distance when the ball is hit with the core of the face is 100% and the flight distance when the core is removed is 95% or more) can be enlarged.

Further, since the deflection of the face does not concentrate near the center of the centroid, the striking energy can be shared over a wide area of the face surface, so that the durability of the face is improved and the ribs are efficiently reinforced. Therefore, it is possible to avoid excessively arranging the ribs, thereby preventing an increase in head weight.

Further, by changing the second moment of area in the longitudinal direction of the rib, the waveform and period of the sound wave transmitted and transmitted through the rib at the time of hitting can be disturbed, thereby improving the hitting sound.

[Brief description of the drawings]

FIG. 1 is a rear view of a face according to an embodiment.

FIG. 2 is a sectional view of a face according to the embodiment.

FIG. 3 is a diagram illustrating a deflection distribution of a face according to an example.

FIG. 4 is a rear view of a face of a comparative example.

FIG. 5 is a diagram illustrating a deflection distribution of a face of a comparative example.

FIG. 6 is a diagram showing another embodiment.

[Explanation of symbols]

 Reference Signs List 1 face 2 back 3 annular rib 4 heel 5 toe 6 crown 7 leading edge 10 face 20 back 30a annular rib 30b annular rib

Claims (2)

[Claims] 1. A golf club head having a hollow structure having a loft angle of 5 to 30 °, wherein a plurality of convex ribs are arranged in a region from the heel side to the toe side of the back surface of the face of the head. A golf club head, wherein a second moment of area of at least one of the ribs is variable in a longitudinal direction of the rib. 2. The second moment of area is 15 mm ⁴ or more.
2. The golf club head according to claim 1, wherein the diameter is 2 × 10 ⁻³ mm ⁴ .