JP2007089831A - Golf club head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a golf club head which has a high repulsion capacity while a face reinforcement effect is increased by ribs. <P>SOLUTION: The golf club head is so constituted that the ribs 14, 16, 18, 20, 22 and 24 are provided in a back face 2b of the golf club head, more than four ribs are disposed to extend from the center section of the face to the peripheral section of the face, angles θ1-θ6 made by the directions of extension between the mutually adjacent ribs are 120° or less, the maximum width of the rib W1 at a prescribed section of the rib is 8-14 mm, the height h of the rib at the prescribed section of the rib is 0.5-1.5 mm, the prescribed section of the rib has a flat section at the upper part of the rib, the width of the flat section W2 is 3-6 mm, and a ratio (W2/W1) of the width of the flat section W2 to the maximum width of the rib W1 is 0.25-0.60, wherein both sides of a rib boundary section or the flat section may be rounded. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a golf club head having a face back reinforced with ribs.

In recent years, golf club heads tend to be larger and thinner. The strength of a wide and thin face tends to decrease. In order to increase the face strength while reducing the thickness of the face, a technique of providing a rib on the back surface of the face is known. Japanese Patent Application Laid-Open No. 2003-290396 provides a plurality of ribs extending in the vertical direction, the height of the ribs is lowered as the ribs on the toe side and the heel side, and the height distribution in each rib is in the longitudinal direction. Disclosed is a golf club head that is either constant or higher (lower the sole).
JP 2003-290396 A

In the above conventional golf club head, the reinforcing effect of the face strength (hereinafter also referred to as the face reinforcing effect) is not sufficient for a large rib volume (rib weight). Further, since all the ribs extend in the vertical direction, the face rigidity is excessive. In particular, ribs extending in the vertical direction on the toe side and heel side of the face make the face rigidity excessive. Excessive face rigidity excessively restrains face vibration during impact. If the face vibration is excessively high, the resilience performance of the head is degraded. An object of the present invention is to provide a golf club head having high resilience performance while enhancing the face reinforcing effect by the ribs.

  The golf club head of the present invention has four or more ribs extending from the center of the face toward the peripheral edge of the face on the back surface of the face. An angle θ (degree) formed by the extending direction between the adjacent ribs is 120 degrees or less. The rib maximum width W1 of the predetermined portion of the rib is 8 to 14 mm. The rib height of the predetermined part of the rib is 0.5 to 1.5 mm. The predetermined part of the rib has a flat part on the upper part of the rib, and the width W2 of the flat part is 3 to 6 mm. The ratio (W2 / W1) between the rib maximum width W1 and the flat portion width W2 is 0.25 to 0.60. The golf club head is equipped with a shaft and a grip and used as a golf club.

  Preferably, the golf club head has a face thickness of 0.5 to 3.5 mm.

  Since four or more ribs extending from the center of the face toward the peripheral edge of the face are provided, and the cross-sectional shape of the predetermined portion of the rib and the arrangement of the ribs are set appropriately, it is possible to achieve both the face reinforcing effect and the resilience performance. .

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view showing an entire golf club head (hereinafter also simply referred to as a head) 1 according to a first embodiment of the present invention. The head 1 is a so-called wood type golf club head. The head 1 includes a face portion 2 that comes into contact with the ball at the time of hitting, a crown portion 3 that extends from the upper edge of the face portion 2 to the rear of the head, and an upper surface of the head 1. For inserting and bonding a shaft (not shown) and a sole portion 4 constituting the lower surface of the head 1, a side portion 5 extending between the crown portion 3 and the sole portion 4 and constituting a portion other than the face portion 2. And a hosel portion 6 having a shaft hole (not shown). A face boundary line k is formed between the face part 2 and other parts (crown part 3, sole part 4, side part 5, etc.). The head 1 has a hollow structure.

  The head 1 is made of metal. The head 1 has a two-piece structure composed of two members. That is, the head 1 is manufactured by joining two preformed members (pieces). The head 1 may be composed of three or more pieces. In FIG. 1, the joint part s between pieces is shown with a virtual line (two-dot chain line). The head 1 is formed by welding and joining a substantially bowl-shaped cup face 1a and a head main body 1b. The cup face 1a and the head main body 1b are welded at the joint s. The cup face 1a includes the entire face portion 2 and a rising portion 11 extending from the periphery of the face portion 2 to the rear of the head. The cup face 1 a is welded to the head main body 1 b at the end surface of the rising portion 11. The cup face 1a constitutes a front portion of the head 1. The head main body 1b constitutes a portion of the head 1 other than the cup face 1a. The rising portion 11 of the cup face 1 a constitutes a face-side portion of the crown portion 3, a face-side portion of the sole portion 4, and a face-side portion of the side portion 5. The head main body 1 b constitutes a back portion of the crown portion 3, a back portion of the sole portion 4, a back portion of the side portion 5, and the hosel portion 6. The cup face 1a and the head main body 1b are made of a titanium alloy. The cup face 1a is produced by a forging method. The head main body 1b is manufactured by a lost wax precision casting method.

  As described above, the head 1 uses the cup face 1a. The face part 2 and the rising part 11 are integrally formed by the cup face 1a. The cup face 1a separates the face boundary line k and the joint portion s. The cup face 1a positions the joint s on the back side with respect to the face boundary line k. When the joint portion s and the face boundary line k are at the same position, stress is likely to concentrate on the joint portion s due to impact force at the time of impact. The rising portion 11 of the cup face 1a contributes to weakening the impact force at the time of hitting acting on the joint portion s.

  The material of the head 1 is not particularly limited. Examples of the material of the head 1 include various metal materials and fiber reinforced plastics. Examples of the metal material include titanium, a titanium alloy, a stainless alloy, an aluminum alloy, and a magnesium alloy. Examples of the titanium alloy include 6Al-4V titanium, 15V-3Cr-3Al-3Sn titanium, 15Mo-5Zr-3Al titanium, 13V-11Cr-3Al titanium, and the like. The member constituting the face portion 2 is preferably β-type titanium having excellent strength. Examples of β-type titanium include 15V-3Cr-3Al-3Sn titanium, 15Mo-5Zr-3Al titanium, and 13V-11Cr-3Al titanium described above. An example of the fiber reinforced plastic is carbon fiber reinforced plastic. The head 1 may be produced by combining the above materials. The face portion 2 is preferably composed of a rolled material or a forged material. The cup face 1a may be made of a rolled material or a forged material. Rolled materials and forged materials have high strength. The crown part 3, the sole part 4 and the side part 5 may be composed of cast members. The casting method has a high degree of freedom in shape. Alternatively, part or all of the crown part 3 may be made of carbon fiber reinforced plastic, and the other part may be produced by casting a metal member. The carbon fiber reinforced plastic used for the crown portion 3 contributes to lowering the center of gravity of the head 1.

The head 1 has a hollow structure as described above. The outer surface of the face portion 2 is a face surface 2a. The face surface 2a is a surface that comes into contact with the ball when hit. The inner surface of the face portion 2 is a face back surface 2b. FIG. 2 is a plan view of the cup face 1a as viewed from the face back surface 2b side. The hatched portion in FIG. 2 shows the end face 12 of the cup face 1a.

  As shown in FIG. 2, ribs 14, 16, 18, 20, 22, and 24 are provided on the face back surface 2b. There are a total of 6 ribs. The ribs 14, 16, 18, 20, 22, 24 reinforce the face part 2. The ribs 14, 16, 18, 20, 22, 24 extend from the center of the face toward the peripheral edge of the face. The ribs 14, 16, 18, 20, 22, 24 extend substantially straight. The ends of the ribs 14, 16, 18, 20, 22, 24 on the face center side of 6 are substantially in the same position. The six ribs 14, 16, 18, 20, 22, 24 are arranged radially. The edges of the ribs 14, 16, 18, 20, 22, 24 reach the face periphery (outer periphery of the face back surface 2 b) 26. In FIG. 2, the portion surrounded by the face outer periphery 26 and the end face 12 of the cup face 1a is the inner surface of the rising portion 11 of the cup face 1a. In each of the ribs 14, 16, 18, 20, 22, 24, the rib cross-sectional shape is substantially constant regardless of the position in the rib longitudinal direction.

  The angles θ1 to θ6 formed by the extending directions between the adjacent ribs are 120 degrees or less. That is, as shown in FIG. 1, the angle θ1 formed by the extending direction between the adjacent ribs 14 and 16 is 120 degrees or less. Further, the angle θ2 formed by the extending direction between the adjacent ribs 16 and 18 is 120 degrees or less. Similarly, an angle θ3 formed by the extending direction between the rib 18 and the rib 20, an angle θ4 formed by the extending direction between the rib 20 and the rib 22, and an extension between the rib 22 and the rib 24. The angle θ5 formed by the existing direction and the angle θ6 formed by the extending direction between the rib 24 and the rib 14 are 120 degrees or less. When the face back surface 2b is non-planar, each angle θ1 to θ6 can be measured in a projected image on a plane perpendicular to a straight line connecting the center of gravity of the head 1 and the sweet spot.

  3 is a cross-sectional view taken along line III-III in FIG. The III-III line is located at a predetermined portion of the rib 14. FIG. 3 shows a cross-sectional shape of the rib 14. The cross-sectional shape of the rib 14 is substantially trapezoidal. The rib 14 is wider toward the lower side. In other words, the rib 14 is wider toward the face surface 2a side. The cross-sectional shapes of the other ribs 16, 18, 20, 22 and 24 are substantially similar to the cross-sectional shape of the ribs 14.

  In the present invention, a cross-sectional shape at a predetermined portion of the rib is defined. The cross-sectional shape of the rib in a portion other than the predetermined portion of the rib can be arbitrarily set. The predetermined portion of the rib is defined as follows. Here, the rib 16 will be described as an example. As shown in FIG. 2, a position A that is separated from the rib longitudinal direction center position 42 of the rib total length L of the rib 16 by 40% (that is, 0.4 L) of the rib total length on one end side of the rib, and a rib longitudinal direction center position 42. A position B separated from the other end of the rib by 40% of the total length of the rib (that is, 0.4 L) is set. From the position A to the position B, the longest portion where the same cross-sectional shape continues is the predetermined portion of the rib 16. The rib total length is the total length in the rib longitudinal direction.

  From the viewpoint of enhancing the effect of the present invention, it is preferable that 60% or more of the range from the position A to the position B is a predetermined portion of the rib, and 80% or more of the range from the position A to the position B is the rib. The predetermined portion is more preferable, and 100% of the range from the position A to the position B is particularly preferably a predetermined portion of the rib.

  In the cross-sectional view of FIG. 3, the upper side of the rib 14 is a flat portion 28. When the flat portion 28 is not provided as in the rib 52 illustrated in FIG. 4C, stress is easily concentrated on the top portion 54 of the rib. The flat portion 28 disperses stress acting on the upper portion of the rib 14 and enhances the durability of the rib.

  From the viewpoint of stress dispersibility, the width W2 of the flat portion is 3 mm or more. Preferably, the width W2 of the flat portion is 4 mm or more. When the width W2 of the flat part is increased, the rigidity of the rib 14 is increased and the rigidity of the face part 2 is also increased. From the viewpoint of suppressing the excessive rigidity of the face portion 2 and increasing the coefficient of restitution, the width W2 of the flat portion is 6 mm or less. Preferably, the width W2 of the flat portion is 5 mm or less. The flat portion width W2 does not include a rounded portion described later.

  In the cross-sectional view of FIG. 3, the minimum value of the width of the rib 14 is the width W2 of the flat portion. In the cross-sectional view, the maximum value W1 of the width of the rib 14 is the width of the bottom of the rib 14. The cross-sectional shape (the shape as shown in FIG. 3) having a larger rib width toward the lower side makes the angle α formed between the rib side surface and the face back surface continuous with it be larger than 90 degrees. In the rib 50 having a rectangular cross section as shown in FIG. 4B, the angle α is relatively small at about 90 degrees. Increasing the angle α alleviates stress concentration near the boundary 40. The relaxation of the stress concentration suppresses cracks in the ribs and increases the face strength.

  The cross-sectional shape (shape as shown in FIG. 3) having a larger rib width toward the lower side makes the angle β formed by the rib side surface and the flat portion 28 larger than 90 degrees. In the rib 50 having a rectangular cross section as shown in FIG. 4B, the angle β is relatively small at about 90 degrees. Increasing the angle β relaxes the stress concentration on the corner portions on both sides of the flat portion 28. The relaxation of the stress concentration suppresses cracks in the ribs and increases the face strength.

  In the rib 50 having a rectangular cross section as shown in FIG. 4B, the maximum rib width W1 tends to be narrow. The narrow maximum rib width W1 increases the stress concentration on the rib. Due to the small angle β and the maximum width W1 of the narrow rib, stress concentration near the rib boundary line 56 is easily performed. Due to the stress concentration, cracks are likely to occur near the rib boundary line 56. In the rib 50 having a rectangular cross section, a tensile stress acts on the flat surface 60 due to deformation of the face portion 2 at the time of impact. This tensile stress tends to concentrate on the corner 62. Cracks are likely to occur near the corner 62 due to the stress concentration.

  The corners on both sides of the flat portion 28 are rounded. The radius of curvature of this roundness is R2. This roundness is convex. The boundary portion of the rib 14 (the boundary portion between the rib and the non-rib portion) is rounded. The radius of curvature of this roundness is R1. This roundness is concave. The roundness of the corners of the ribs alleviates stress concentration on the corners. This relaxation suppresses cracks generated at the rib corners and increases the face strength.

  From the viewpoint of the face reinforcing effect and the relaxation of stress concentration on the rib, the maximum width W1 of the rib is preferably 8 mm or more. Preferably, the maximum width W1 of the rib is 10 mm or more. From the viewpoint of suppressing an excessive increase in face rigidity and improving the coefficient of restitution, the maximum rib width W1 is preferably 14 mm or less. Preferably, the maximum width W1 of the rib is 12 mm or less.

  From the viewpoint of the face reinforcing effect, the rib height h is preferably 0.5 mm or more. Preferably, the rib height h is 0.7 mm or more. From the viewpoint of suppressing an excessive increase in face rigidity and improving the coefficient of restitution, the rib height h is preferably 1.5 mm or less. Preferably, the rib height h is 1.3 mm or less.

  The ratio (W2 / W1) is preferably set to 0.25 or more from the viewpoint of increasing the flat portion width W2 to alleviate the stress concentration at the rib top. Preferably, the ratio (W2 / W1) is 0.30 or more, more preferably 0.35 or more. From the viewpoint of reducing the weight of the rib, the ratio (W2 / W1) is preferably 0.6 or less. Preferably, the ratio (W2 / W1) is 0.55 or less, more preferably 0.50 or less.

  From the viewpoint of alleviating stress concentration at the corner, the radius of curvature R1 of the roundness at the rib boundary is preferably 10 mm or more. More preferably, the radius of curvature R1 is 15 mm or more, and more preferably 20 mm or more. From the viewpoint of weight reduction of the rib, the curvature radius R1 is preferably 50 mm or less. More preferably, the radius of curvature R1 is 45 mm or less, particularly preferably 40 mm or less.

  From the viewpoint of alleviating stress concentration on the corner, the radius of curvature R2 of the roundness on both sides of the flat portion is preferably 2.0 mm or more. More preferably, the radius of curvature R2 is preferably 3.0 mm or more, and particularly preferably 4.0 mm or more. From the viewpoint of increasing the width W2 of the flat portion, the curvature radius R2 is preferably 10 mm or less. More preferably, the radius of curvature R2 is 9.0 mm or less, and particularly preferably 8.0 mm or less.

  From the viewpoint of alleviating local stress concentration on the corners or the like, the minimum curvature radius Rm in the cross-sectional shape of the rib is preferably 2.0 mm or more, more preferably 3.0 mm or more, and particularly preferably 6.0 mm or more. The minimum curvature radius Rm refers to the one having the smallest curvature radius among all the roundnesses (including the roundness of the rib boundary and the roundness on both sides of the flat part) existing in the cross-sectional shape of the rib.

  If the radius of curvature R1 of the roundness of the rib boundary portion is too small with respect to the radius of curvature R2 of the roundness on both sides of the flat portion, stress tends to concentrate on the rib boundary portion and cracks are likely to occur at the rib boundary portion. From the viewpoint of alleviating stress concentration at the rib boundary, the ratio (R1 / R2) value is preferably 2.0 or more, more preferably 2.5 or more, and particularly preferably 3.0 or more. If the radius of curvature R2 of the roundness on both sides of the flat part is too small with respect to the radius of curvature R1 of the roundness of the rib boundary part, stress tends to concentrate on both sides of the flat part and cracks are likely to occur on both sides of the flat part. Become. In light of alleviating stress concentration on both sides of the flat portion, the ratio (R1 / R2) is preferably 20.0 or less, more preferably 18.0 or less, and particularly preferably 14.0 or less.

  On both sides in the width direction of each of the ribs 14, 16, 18, 20, 22, and 24, there are boundary lines 40 that partition the ribs and the non-rib portions. Round portions R3, R4, R5, R6, R7, and R8 having a radius of curvature of 1 to 15 mm are given to portions where the boundary lines 40 of adjacent ribs intersect each other (see FIG. 2). Each roundness R3, R4, R5, R6, R7 and R8 is smoothly continuous with both of the boundary lines 40. The roundness R3, R4, R5, R6, R7, and R8 alleviates stress concentration at the portion where the boundary lines 40 intersect. The relaxation of the stress concentration improves the durability of the face portion 2. From the viewpoint of relaxing stress concentration and improving durability, the radius of curvature of the roundness R3, R4, R5, R6, R7 and R8 is preferably 1 mm or more, and more preferably 2 mm or more. On the other hand, when the curvature radii of the roundness R3, R4, R5, R6, R7, and R8 are increased, the area of the rib is increased and the rigidity of the face is increased. From the viewpoint of suppressing an excessive increase in face rigidity and improving the head restitution coefficient, the radius of curvature of the roundness R3, R4, R5, R6, R7 and R8 is preferably 15 mm or less, more preferably 14 mm or less, and particularly preferably 12 mm or less. .

Arranging the ribs 14, 16, 18, 20, 22, 24 from the center of the face toward the periphery of the face distributes the stress acting on the face more evenly without excessively increasing the face rigidity. From the viewpoint of improving the face strength by narrowing the ribless area between adjacent ribs, the number of ribs arranged from the center of the face toward the peripheral edge of the face is preferably 4 or more, more preferably 5 or more. 6 or more are more preferable. From the viewpoint of suppressing an excessive increase in face rigidity and improving the coefficient of restitution, the number of ribs arranged from the center of the face toward the peripheral edge of the face is preferably 15 or less, more preferably 10 or less, and 8 or less. Is particularly preferred.

  Further, from the viewpoint of improving the face strength by narrowing the rib-free region between adjacent ribs, the angle formed by the extending directions between the adjacent ribs is preferably 120 degrees or less, and 110 degrees or less. More preferably, 100 degrees or less is still more preferable, and 90 degrees or less is particularly preferable. From the viewpoint of suppressing an excessive increase in face rigidity and improving resilience performance, the angle formed by the extending directions between the adjacent ribs is preferably 15 degrees or more, and more preferably 30 degrees or more. Preferably, it is 40 degrees or more, more preferably 50 degrees or more.

  The rib concentrated portion 44 (portion surrounded by a hexagonal broken line in FIG. 2) is preferably located in a range including the center of gravity of the face back surface 2b. If the rib concentrated portion 44 is too close to the face peripheral edge side, the uniform dispersibility of stress acting on the face to each rib is reduced. The rib concentration portion 44 is a portion formed by a plurality of ribs extending from the center of the face toward the peripheral edge of the face.

  The face thickness T is preferably 0.5 mm or more. When the thickness is 0.5 mm or more, the face strength is improved. From the viewpoint of improving the face strength, the face thickness T is more preferably 1.0 mm or more, and particularly preferably 1.5 mm or more. The face thickness T is preferably 3.5 mm or less. By setting the thickness to 3.5 mm or less, an excessive increase in face rigidity is suppressed and the resilience performance is improved. From the viewpoint of improving resilience performance, the face thickness T is more preferably 3.0 mm or less, and particularly preferably 2.7 mm or less. The face thickness T does not include the rib thickness (rib height h).

  From the viewpoint of increasing the dispersibility of the stress acting on the center of the face, it is preferable that the end of the rib on the face center side is disposed within a range of 4 mm from the center of gravity (not shown) of the face back surface 2b. From the viewpoint of increasing the stress dispersibility to the face peripheral portion, it is preferable that the end portion on the face peripheral portion side of the rib is disposed within a range within 5 mm from the face outer periphery 26, and further to the face outer periphery 26. preferable.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
A cup face similar to that of the above-described embodiment and the head main body were welded to produce a hollow titanium alloy head. The volume of this head was 405 cc, the face area (face surface area) was 4100 mm ² , and the face thickness T was 1.8 mm to 2.0 mm. The cross-sectional shape of the rib is the same as that of the above-described embodiment, and is as shown in FIG. There are six ribs. θ1, θ2, θ3, θ4, θ5, and θ6 are about 60 degrees. The cross-sectional shape of the rib was constant regardless of the longitudinal position of the rib. The maximum width W1 of the rib was 12 mm, and the width W2 of the flat portion was 4.0 mm. The rib height h was 1.00 mm. The radius of curvature R1 of the roundness of the rib boundary portion was 30.0 mm. The radius of curvature R2 of the roundness on both sides of the flat part was 6.0 mm. The minimum curvature radius Rm was 6.0 mm. The minimum curvature radius Rm is a curvature radius R2 of roundness on both sides of the flat portion.

[Examples 2 to 3, Comparative Examples 3 to 4]
A golf club head was obtained in the same manner as in Example 1 except that the maximum rib width W1 was changed to the value shown in Table 1.

[Example 6, Comparative Examples 5-6, Comparative Examples 9-11]
A golf club head was obtained in the same manner as in Example 1 except that the flat portion width W2 was set to the value shown in Table 1.

[Examples 4-5, Comparative Examples 7-8]
A golf club head was obtained in the same manner as in Example 1 except that the rib height h was set to the value shown in Table 1.

[Examples 7 to 10]
A golf club head was obtained in the same manner as in Example 1 except that the curvature radius R2 of the roundness on both sides of the flat portion was set to the value shown in Table 1.

[Comparative Example 1]
Golf as in Example 1 except that the maximum rib width W1, the rib height h, the radius of curvature R1 of the roundness of the rib boundary, and the radius of curvature R2 of the roundness on both sides of the flat portion were set to the values shown in Table 1. Got the club head. The cross-sectional shape of the rib in Comparative Example 1 is substantially rectangular. The cross-sectional shape of the rib of Comparative Example 1 is obtained by rounding the rib boundary line 56 and the corner 62 in the cross section of FIG.

[Comparative Example 2]
A golf club head was obtained in the same manner as in Example 1 except that the flat portion was eliminated and the rib height h was changed to the value shown in Table 1. The cross-sectional shape of Comparative Example 2 is shown in FIG. The apex of the rib in Comparative Example 2 is rounded.

[Durability evaluation]
A golf club was manufactured by attaching a common shaft and grip to the head of each example. A commercially available golf ball was hit with this golf club. The hit was made by a swing robot. The head speed was 50 (m / s). The hitting point was the face center. The number of hits until the head is destroyed is shown in Table 1 below.

[Durability determination]
Judgment was made based on the number of hits until destruction. When the number of hits until destruction is 10,000 times or more, the durability judgment is “○”, and when the number of hits until destruction is less than 10,000, the durability judgment is “×”. It was done. This determination is shown in Table 1 below.

[Evaluation of coefficient of restitution]
The coefficient of restitution is the U.S. S. G. A. The method was measured by a method similar to Procedure for Measuring the Velocity Ratio of a Club Head for Conformance to Rule 4-1e, Revision 2 (February 8, 1999). Specifically, a golf ball is launched using a ball launching device and is made to collide with the vicinity of the face center point of the head placed without being fixed on the pedestal. In measuring the coefficient of restitution, the ball is caused to collide at a right angle with respect to the face surface at a position not more than 5 mm away from the face center point of the head. Then, the incident velocity Vi and the rebound velocity Vo immediately before the collision of the golf ball were measured. Further, when the incident velocity of the golf ball is Vi, the rebound velocity is Vo, the head mass is M, and the average mass of the golf ball is m, the restitution coefficient e is calculated by the following equation (A). Note that the distance from the launch port of the golf ball to the face portion was 1 m, the pinnacle gold manufactured by Titleist was used for the golf ball, and the initial velocity of the ball was set to 48.77 m / s. The position of the speed sensor was set at 360.2 mm and 635 mm from the head. The calculated coefficient of restitution is shown in Table 1 below.

  (Vo / Vi) = (eM−m) / (M + m) (A)

[Determination of coefficient of restitution]
Those with a restitution coefficient of 0.860 or more were rated as “◯”, and those with a restitution coefficient of less than 0.860 were rated as “x”. This determination is shown in Table 1 below.

As shown in Table 1, in the examples, both the durability and the coefficient of restitution were evaluated as “◯”. On the other hand, in the comparative example, at least one of the durability and the coefficient of restitution was evaluated as “x”. From this evaluation result, the superiority of the present invention is clear.

FIG. 1 is a perspective view of a golf club head according to one embodiment (and Example 1) of the present invention. FIG. 2 is a plan view of the cup face of the golf club head according to one embodiment (and Example 1) of the present invention as seen from the back face side. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4A is a cross-sectional view of a rib according to another embodiment of the present invention. FIG. 4B is a cross-sectional view of the rib of the comparative example. FIG.4 (c) is sectional drawing of the rib of another comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Golf club head 2 ... Face part 2a ... Face surface 2b ... Face back surface 14, 16, 18, 20, 22, 24, 46 ... Rib 28, 48 ... Flat part W1 ... Maximum width of rib W2 ... Width of flat portion R1 ... Round curvature radius of rib boundary portion R2 ... Round curvature radius of both sides of flat portion θ1, θ2, θ3, θ4, θ5 , Θ6 ... An angle formed by the extending direction between adjacent ribs

Claims (3)

Four or more ribs extending from the center of the face toward the peripheral edge of the face are provided on the back face of the face.
The angle θ (degree) formed by the extending direction between the ribs adjacent to each other is 120 degrees or less,
The rib maximum width W1 of the predetermined portion of the rib is 8 to 14 mm,
The rib height of the predetermined part of the rib is 0.5 to 1.5 mm,
The predetermined portion of the rib has a flat portion on the upper portion of the rib, and the width W2 of the flat portion is 3 to 6 mm.
A golf club head in which a ratio (W2 / W1) between the maximum rib width W1 and the width W2 of the flat portion is 0.25 to 0.60.   The golf club head according to claim 1, wherein the face thickness is 0.5 to 3.5 mm. A shaft,
A grip attached to one end of the shaft;
A golf club head attached to the other end of the shaft,
The golf club head has four or more ribs extending from the center of the face toward the periphery of the face on the back surface of the face.
The angle θ (degree) formed by the extending direction between the ribs adjacent to each other is 120 degrees or less,
The rib maximum width W1 of the predetermined portion of the rib is 8 to 14 mm,
The rib height of the predetermined part of the rib is 0.5 to 1.5 mm,
The predetermined portion of the rib has a flat portion on the upper portion of the rib, and the width W2 of the flat portion is 3 to 6 mm.
A golf club having a ratio (W2 / W1) of the maximum rib width W1 to the width W2 of the flat portion of 0.25 to 0.60.

Images