JP2011098039A - Iron golf club head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an iron golf club head which allows an increase in the number of spins of a ball while adapting to the revised rules of R&A. <P>SOLUTION: The iron golf club head is provided with a groove 20 including: a first sidewall 21 leading to a face surface 11; a second sidewall 22 leading to the first sidewall 21; and a bottom 23 leading to the second sidewall 22. The width W1 of the groove 20 measured by a 30° measurement method is 0.76-0.88 mm. At the connection portion 24 of the face surface 11 and the first sidewall 21, roundness having a curvature radius R of 0.05-0.3 mm is formed. At the connection portion 25 of the first sidewall 21 and the second sidewall 22, roundness is formed. The depth D1 from the face surface 11 to the bottom 23 is 0.38-0.50 mm. The tilt angle θ1 of the first sidewall 21 with respect to the surface perpendicular to the face surface 11 is 36°-40°. The tilt angle θ2 of the second sidewall 22 with respect to the surface perpendicular to the face surface 11 is 5°-10°. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an iron golf club head, and more particularly to an iron golf club head having score lines formed on a face portion.

  A plurality of grooves called score lines are formed in the face portion of the iron golf club. This groove affects the spin number of the ball. This groove is preferably formed so as to increase the spin number of the ball.

  For example, Japanese Patent Application Laid-Open No. 2008-114007 discloses a golf club head for preventing the ball spin rate from being greatly reduced and preventing the ball from being damaged in the case of a rainy day or a shot from a rough surface. It is disclosed. In the golf club head described in this publication, the pair of side surfaces of the groove has a first surface continuous from the face surface and a second surface continuous with the first surface. A first angle formed by each of the pair of first surfaces is larger than a second angle formed by each of the pair of second surfaces.

JP 2008-114007 A

  Due to the revision of the rules of R & A (Royal and Ancient Golf Club of St Andrews), the shape of the groove in the impact area will be restricted after January 1, 2010. Specifically, in addition to the conventionally defined groove width and depth, the radius of the edge roundness, the ratio of the groove width to the cross-sectional area, and the groove spacing are defined. That is, more specifically, a club is considered non-conforming if it does not meet the following rules:

As for the width of the groove, 50% or more of the number measured by the 30 ° measurement method should be 0.889 mm or less. This 30 ° measurement method (R & A regulation internal rule) is a method of measuring the distance between two points where a straight line inclined by 30 ° with respect to the face surface contacts the edge of the groove as the groove width. As for the depth of the groove, 50% or more of the measured number should be 0.508 mm or less. The radius of the roundness of the groove edge must be concentric on a concentric circle having a radius of 0.254 mm or more and 0.508 mm or less by the two-circle method. This two-circle method (R & A rule internal rule) is that if the edge of the groove protrudes from a circle having a radius of 0.011 inch concentric with a circle having a radius of 0.010 inch in contact with the side wall of the groove and the adjacent face surface. This is a method that does not conform to the principle. The ratio of the groove width and the groove interval to the cross-sectional area is obtained by dividing the groove cross-sectional area (A) by the sum of the groove width (W) and the groove interval (S) ((A) / ( (W) + (S))) should not exceed 0.0030 inches (0.0762 mm ² / mm).

  This rule revision is likely to reduce the number of spins of the ball compared to before the revision. On the other hand, there is a desire to increase the spin number while satisfying the revised rule.

  In the golf club head disclosed in the above publication, a corner is formed between the first surface and the second surface. Since these corners are sharp, the golf club head disclosed in the above publication does not satisfy the definition of the radius of roundness of the groove edge in the R & A rule. Therefore, the golf club head of the above publication does not conform to the revised R & A rules.

  The present invention has been made in view of the above problems, and an object thereof is to provide an iron golf club head that can increase the spin number of a ball while conforming to the revised R & A rules.

  An iron golf club head of the present invention includes a face portion having a face surface, a first side wall portion formed on the face portion and continuing to the face surface, and a second side wall portion continuing to the first side wall portion, A groove portion having a bottom portion continuous with the second side wall portion, the width of the groove portion measured by the 30 ° measurement method is not less than 0.76 mm and not more than 0.88 mm, and the face surface and the first side wall portion The connecting portion is rounded with a curvature radius of 0.05 mm or more and 0.3 mm or less, and the connecting portion between the first side wall and the second side wall is rounded, from the face surface to the bottom. The depth of the first sidewall portion is 0.38 mm or more and 0.5 mm or less, and the inclination angle of the first side wall portion with respect to the surface perpendicular to the face surface is 36 ° or more and 40 ° or less. The inclination angle of the side wall of 2 is 5 ° or more 0 ° is less than or equal to.

  As a result of intensive studies by the inventor, the width of the groove, the roundness of the connection portion between the face surface and the first side wall portion, the roundness of the connection portion between the first side wall portion and the second side wall portion, from the face surface to the bottom portion It was found that the depth of the first side wall, the inclination angle of the first side wall portion with respect to the surface perpendicular to the face surface, and the inclination angle of the second side wall portion with respect to the surface perpendicular to the face surface influence the spin number. And, according to the iron golf club head of the present invention having the above groove shape, it has been found that the spin number of the ball can be increased while conforming to the revised R & A rule.

  The iron golf club head is preferably made of a material including JIS standard S25C.

  As described above, according to the iron golf club head of the present invention, the spin number of the ball can be increased while conforming to the revised R & A rules.

1 is a schematic front view of an iron golf club head according to an embodiment of the present invention. It is a schematic sectional drawing of the groove part of the iron golf club head in one embodiment of this invention. It is a figure which shows the relationship between the groove part width | variety of an iron golf club head, and a spin number. It is a figure which shows the relationship between the curvature radius of the groove part of an iron golf club head, and a spin number. It is a figure which shows the relationship between the groove part depth of an iron golf club head, and a spin number. It is a figure which shows the relationship between the 1st side wall part inclination | tilt angle of an iron golf club head, and a spin number. It is a figure which shows the relationship between the 2nd side wall part inclination | tilt angle of an iron golf club head, and a spin number. 6 is a schematic cross-sectional view of a groove portion of Comparative Example A. FIG. 6 is a schematic cross-sectional view of a groove portion of Comparative Example B. FIG. It is a schematic sectional drawing of the groove part of the example C of this invention. It is a schematic sectional drawing of the groove part of this invention example C1. It is a schematic sectional drawing of the groove part of this invention example C2. It is a schematic sectional drawing of the groove part of this invention example C3. It is a figure which shows the spin number of the example of this invention and a comparative example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, an overall configuration of an iron golf club head according to an embodiment of the present invention will be described.

  Referring to FIG. 1, iron golf club head 1 of the present embodiment mainly has a face portion 10 and a plurality of groove portions 20. The face portion 10 has a face surface 11 that is a ball striking surface. A groove portion 20 is formed in the face portion 10. The groove 20 is formed continuously on the face surface 11. The plurality of groove portions 20 are formed at substantially equal intervals in the direction of longitudinally cutting the face surface 11. The plurality of grooves 20 are formed in a straight line in a direction crossing the face surface 11.

  The iron golf club head 1 also has a hosel part to which a shaft (not shown) is connected. The iron golf club head 1 also has a top edge portion, a toe portion, a sole portion, and a heel portion located around the face portion 10. A top edge part is a part which comprises the upper end edge part of the iron golf club head 1 main body from a hosel part to a toe part. A sole part is a part which comprises the bottom part of iron golf club head 1 main body. The toe portion is a portion that connects the top edge portion and the sole portion on the side away from the hosel portion. The heel part is a part from the lower end of the hosel part to the sole part. The iron golf club head 1 also has a back portion (not shown) on the back side of the face portion 10.

  The iron golf club head 1 can be manufactured using a material including, for example, JIS standard S25C. The iron golf club head 1 can also be manufactured by forging or casting using one or more materials such as stainless steel, soft iron, maraging steel, pure titanium, titanium alloy, and aluminum alloy. .

  The iron golf club head 1 may be plated. The plating may be, for example, Ni (nickel) -Cr (chromium) plating. The Cr layer may be 5 μm and the Ni layer may be 20 μm.

  An iron golf club is formed by combining the iron golf club head 1 with a shaft and a grip. In addition, a well-known thing is employable as a shaft and a grip.

  Next, the structure of the groove part of the iron golf club head of this Embodiment is demonstrated in detail.

  With reference to FIG. 2, the groove 20 is continuous with the first side wall 21 that is continuous with the face surface 11, the second side wall 22 that is continuous with the first side wall 21, and the second side wall 22. And a bottom portion 23. The first side wall part 21 and the second side wall part 22 are formed as a pair facing each other with the bottom part 23 interposed therebetween.

  The width W1 of the groove 20 measured by the 30 ° measuring method is the distance between two points where the straight line inclined by 30 ° with respect to the face surface 11 contacts the connecting portion 24 between the face surface 11 and the first side wall 21. To do. The width W1 of the groove 20 measured by the 30 ° measurement method is 0.76 mm or more and 0.88 mm or less.

  The connecting portion 24 between the face surface 11 and the first side wall 21 is rounded with a radius of curvature R of 0.05 mm or more and 0.3 mm or less. The connecting portion 25 between the first side wall portion 21 and the second side wall portion 22 is rounded. The connection portion 25 between the first side wall portion 21 and the second side wall portion 22 has a gentle shape instead of a sharp shape in a cross-sectional view.

  The distance in the direction perpendicular to the face surface 11 between the face surface 11 and the bottom portion 23 is the depth D1 from the face surface 11 to the bottom portion 23. The depth D1 from the face surface 11 to the bottom 23 is not less than 0.38 mm and not more than 0.5 mm. The distance between the face surface 11 and the connecting portion 25 in the direction perpendicular to the face surface 11 is the first side wall portion depth (depth of the first side wall portion 21) D2. The distance in the direction perpendicular to the face surface 11 between the connection portion 25 and the bottom portion 23 is the second side wall portion depth (depth of the second side wall portion 22) D3.

  The inclination angle θ1 of the first side wall portion 21 with respect to the plane perpendicular to the face surface 11 is 36 ° or more and 40 ° or less. The inclination angle θ2 of the second side wall portion 22 with respect to the plane perpendicular to the face surface 11 is not less than 5 ° and not more than 10 °. The width of the bottom 23 in a cross-sectional view is the bottom width W2. The bottom 23 is preferably formed substantially parallel to the face surface 11. A plurality of groove portions 20 are formed with an interval S between the groove portions.

Next, the function and effect of the iron golf club head of the present embodiment will be described.
As a result of intensive studies by the inventor, it has been found that according to the iron golf club head 1 having the shape of the groove 20 of the present embodiment, the spin number of the ball can be increased while conforming to the revised R & A rules. . The reason is as follows.

  In the iron golf club head 1 of the present embodiment, the width W1 of the groove 20 measured by the 30 ° measurement method is 0.76 mm or more and 0.88 mm or less. The width W1 of the groove 20 is 0.88 mm or less. Therefore, the groove width of the revised R & A rule is adjusted to 0.889 mm or less, and the width W1 of the groove portion 20 is set to 0.76 mm or more, so that the groove cross-sectional area A is increased and the biting into the ball is improved. It is something to try. In addition, by setting the width of the groove 20 to be 0.76 mm or more, the turf interposed between the ball and the head is easily removed during rough shots. In addition, the drainage is improved when wet, so the number of spins in the rain can be increased.

  The roundness of the curvature radius R 0.05 mm or more and 0.3 mm or less is given to the connection portion 24 between the face surface 11 and the first side wall portion 22 because the curvature radius R is set to 0.05 mm or more. Even if the inclination angle θ1 of the side wall 21 is 36 °, it is adapted to the radius of the rounded groove of the revised R & A rule, and the curvature radius R is set to 0.3 mm or less so that the face surface 11 and the first The connection portion 24 with the one side wall portion 21 is firmly brought into contact with each other to increase the spin number.

  The reason why the connecting portion 25 between the first side wall portion 21 and the second side wall portion 22 is rounded is that it can be adapted to the radius of the rounded groove of the revised R & A rule. is there.

  The depth D1 from the face surface 11 to the bottom portion 23 is set to 0.38 mm or more and 0.5 mm or less because the depth D1 from the face surface 11 to the bottom portion 23 is set to 0.5 mm or less after the above revision. The groove depth of 0.508 mm or less is adapted to the rule, and the depth D1 from the face surface 11 to the bottom 23 is set to 0.38 mm or more to increase the groove cross-sectional area A and improve the bite into the ball. It is something to try. Further, by setting the depth of the groove 20 to 0.38 mm or more, the grass interposed between the ball and the head is easily removed during rough shots. In addition, the drainage is improved when wet, so the number of spins in the rain can be increased.

  The inclination angle θ1 of the first side wall portion 21 with respect to the plane perpendicular to the face surface 11 is set to 36 ° or more and 40 ° or less because the inclination angle θ1 of the first side wall portion 21 with respect to the plane perpendicular to the face surface 11 is set to 36. By setting the angle to be greater than or equal to °, even if the radius of curvature R is 0.05 mm, the radius of the first side wall 21 is inclined with respect to the surface perpendicular to the face surface 11 by adapting to the radius of the groove of the revised R & A rule. By setting the angle θ1 to 40 ° or less, the bottom 23 is prevented from becoming smaller corresponding to the width W1 of the groove 20 of the revised R & A rule, and the groove cross-sectional area A is increased to the ball. It is intended to improve the bite. Moreover, since the drainage is improved by setting the inclination angle θ1 of the first side wall portion 21 to 40 ° or less, it is possible to increase the spin number particularly in rainy weather.

  The inclination angle θ2 of the second sidewall portion 22 with respect to the plane perpendicular to the face surface 11 is set to 5 ° or more and 10 ° or less because the inclination angle θ2 of the second sidewall portion 22 with respect to the plane perpendicular to the face surface 11 is 5 By making the angle 20 ° or more, the processing of the groove portion 20 becomes easy and manufacturing management becomes easy. By making the inclination angle θ2 of the second side wall portion 22 with respect to the surface perpendicular to the face surface 11 less than 10 °, the groove portion is cut off. The area A is increased to improve the bite into the ball. Moreover, since the drainage is improved by setting the inclination angle θ2 of the second side wall portion 22 to 10 ° or less, the spin number can be increased particularly in rainy weather.

  The iron golf club head 1 of the present embodiment is preferably made of a material including JIS standard S25C.

  Embodiment 1 of the present invention will be described below. Invention Example C is an embodiment of the present invention. Invention Examples D, E, H, M, P, Q, T, U, and V are modifications of the present invention. Comparative Examples F, G, I, J, N, O, R, S, W, and X are comparative examples for the present invention. In addition, the same reference number is attached | subjected to the part which is the same or it corresponds, and the description may not be repeated.

  With reference to FIG. 2 and Tables 1 to 5, the relationship between the shape of the groove 20 of the iron golf club head and the spin number T will be described.

  Iron golf club heads in which the values of the respective symbols of the groove portions 20 of the iron golf club head shown in FIG. 2 are the same as those of the present invention example and the comparative example shown in Tables 1 to 5 are respectively produced. did. The loft angle of each iron golf club head is 56 °. As a material of each iron golf club head, JIS standard S25C was used. Each iron golf club head was Ni-Cr plated. Here, the Cr layer was 5 μm, and the Ni layer was 20 μm.

  The spin performance of each iron golf club head was examined by a robot test. More specifically, the number of spins T was measured by hitting a ball with each iron golf club head using a mechanical golfer manufactured by Miyamae Co., Ltd. Specifically, the spin number T in the dry state of 100 years was measured. Each of the iron golf club heads hit five balls. In the column of the number of spins T in Tables 1 to 5, the average value of the number of spins T of the balls hit by five balls each is described. The ball used Titleest Pro V1. The location of the hitting point was the score line center (the central portion in the longitudinal direction of the groove portion 20 of the face surface 11), and was between the second groove portion from the top edge portion and the third groove portion from the sole portion. The spin number T of the ball was measured with a trajectory measuring instrument Trackman manufactured by Interactive Sports Games.

  The relationship between the groove width W1 and the spin number T will be described with reference to Table 1 and FIG. As shown in Table 1, in Invention Examples C, D, E and Comparative Examples F, G, the groove width W1, the groove interval S, the bottom width W2, the groove cross-sectional area A, the groove width W1 and the groove width relative to the groove cross-sectional area A and the groove The ratio A / (W1 + S) of the interval S is different.

  For Invention Examples C, D, and E, the width (groove width) W1 of the groove 20 measured by the 30 ° measurement method is 0.76 mm or more and 0.831 mm or less. On the other hand, for Comparative Examples F and G, the width (groove width) W1 of the groove 20 measured by the 30 ° measurement method is 0.74 mm or less.

  As shown in FIG. 3, the spin numbers T (rpm) of the inventive examples C, D and E are significantly higher than the spin numbers T of the comparative examples F and G. Thereby, it was found that the spin number T can be increased by setting the width (groove width) W1 of the groove 20 measured by the 30 ° measurement method to 0.76 mm or more and 0.831 mm or less. This tendency for the spin number T to increase is considered to be the same until the groove width W1 is 0.88 mm.

  Therefore, the upper limit of the width (groove width) W1 of the groove 20 measured by the 30 ° measurement method is 0.88 mm from the above R & A rule that the groove width by the 30 ° measurement method should not exceed 0.889 mm. I decided. On the other hand, the lower limit value of the width (groove width) W1 of the groove 20 measured by the 30 ° measurement method was determined to be 0.76 mm, which is a critical value at which the spin number T was significantly increased in Table 1 and FIG.

  With reference to Table 2 and FIG. 4, the relationship between the curvature radius R and the spin number T will be described. As shown in Table 2, in the inventive examples C, T, U, V and comparative examples W and X, the groove width W1, the groove interval S, the radius of curvature R, the groove cross-sectional area A, and the groove width W1 with respect to the groove cross-sectional area A And the ratio A / (W1 + S) of the groove interval S is different.

  In the inventive examples C, T, U, and V, the connecting portion 24 between the face surface 11 and the first side wall portion 21 is given a roundness with a radius of curvature of 0.05 mm or more and 0.3 mm or less. On the other hand, in Comparative Examples W and X, the radius of curvature of the roundness imparted to the connection portion 24 between the face surface 11 and the first side wall portion 21 is 0.35 mm or more.

  As shown in FIG. 4, the spin numbers T (rpm) of the inventive examples C, T, U, and V are significantly higher than those of the comparative examples W and X. As a result, it was found that the spin number T can be increased by providing the connecting portion 24 between the face surface 11 and the first side wall portion 21 with a radius of curvature R 0.05 mm or more and 0.3 mm or less.

  Therefore, the upper limit value of the radius of curvature R of the connection portion 24 between the face surface 11 and the first side wall portion 21 is determined to be 0.3 mm, which is a critical value in which the spin number T is significantly increased in Table 2 and FIG. It was. On the other hand, the lower limit value of the radius of curvature R of the connecting portion 24 between the face surface 11 and the first side wall portion 21 is the R & A of the revised R & A that the edge of the groove should not protrude from the outer circle by the two-circle method. It was determined to be 0.05 mm from the rule.

  The relationship between the groove depth D1 and the spin number T will be described with reference to Table 3 and FIG. As shown in Table 3, in Invention Examples C and H and Comparative Examples I and J, bottom width W2, groove depth D1, second side wall depth (depth of second side wall portion 22) D3, groove portion The ratio A / (W1 + S) of the cross-sectional area A, the groove width W1 and the groove interval S to the groove cross-sectional area A is different.

  In the inventive examples C and H, the depth D1 from the face surface 11 to the bottom 23 is not less than 0.38 mm and not more than 0.4 mm. On the other hand, in Comparative Examples I and J, the depth D1 from the face surface 11 to the bottom 23 is 0.35 mm or less.

  As shown in FIG. 5, the spin numbers T (rpm) of Invention Examples C and H are significantly higher than those of Comparative Examples I and J. Accordingly, it was found that the spin number T can be increased by setting the depth D1 from the face surface 11 to the bottom 23 to be 0.38 mm or more and 0.4 mm or less. This tendency for the spin number T to increase is considered to be the same when the depth D1 from the face surface 11 to the bottom 23 is 0.5 mm.

  Therefore, the upper limit value of the depth D1 from the face surface 11 to the bottom 23 is determined to be 0.5 mm from the above R & A rule that the depth of the groove should not exceed 0.509 mm. On the other hand, the lower limit value of the depth D1 from the face surface 11 to the bottom 23 was determined to be 0.38 mm, which is a critical value at which the spin number T is significantly increased in Table 3 and FIG.

  With reference to Table 4 and FIG. 6, the relationship between the first sidewall tilt angle (the tilt angle of the first sidewall 21) θ1 and the spin number T will be described. As shown in Table 4, in Invention Examples C and M and Comparative Examples N and O, the groove width W1, the groove interval S, the bottom width W2, the first side wall inclination angle θ1, the groove cross-sectional area A, and the groove cross-sectional area A The ratio A / (W1 + S) of the groove width W1 and the groove interval S is different.

  In the inventive examples C and M, the inclination angle θ1 of the first side wall portion 21 with respect to the plane perpendicular to the face surface 11 is 36 ° or more and 40 ° or less. On the other hand, in Comparative Examples N and O, the inclination angle θ1 of the first side wall portion 21 with respect to the plane perpendicular to the face surface 11 is 45 ° or more.

  As shown in FIG. 6, the spin numbers T (rpm) of Invention Examples C and M are significantly higher than those of Comparative Examples N and O. Accordingly, it was found that the spin number T can be increased by setting the inclination angle θ1 of the first side wall portion 21 with respect to the plane perpendicular to the face surface 11 to 36 ° to 40 °.

  Therefore, the upper limit value of the inclination angle θ1 of the first side wall portion 21 with respect to the plane perpendicular to the face surface 11 is determined to be 40 ° which is a critical value at which the spin number T is significantly increased in Table 4 and FIG. On the other hand, the lower limit value of the inclination angle θ1 of the first side wall portion 21 with respect to the plane perpendicular to the face surface 11 is 0.05 mm where the radius of curvature R is the lower limit value. The angle was determined to be 36 ° in order to meet the revised R & A rule that the edge should not protrude.

  With reference to Table 5 and FIG. 7, the relationship between the second side wall portion inclination angle (inclination angle of the first side wall portion 22) θ2 and the spin number T will be described. As shown in Table 5, in the inventive examples C, P, Q and comparative examples R, S, the bottom width W2, the second side wall inclination angle θ2, the groove section area A, the groove width W1 and the groove section relative to the groove section area A The ratio A / (W1 + S) of the interval S is different.

  In the inventive examples C, P, and Q, the inclination angle θ2 of the second side wall portion 22 with respect to the plane perpendicular to the face surface 11 is 5 ° or more and 10 ° or less. On the other hand, in Comparative Examples R and S, the inclination angle θ2 of the second side wall portion 22 with respect to the plane perpendicular to the face surface 11 is 12 ° or more.

  As shown in FIG. 7, the spin numbers T (rpm) of the inventive examples C, P, and Q are significantly higher than those of the comparative examples R and S. Accordingly, it was found that the spin number T can be increased by setting the inclination angle θ2 of the second side wall portion 22 with respect to the plane perpendicular to the face surface 11 to 5 ° or more and 10 ° or less.

  Therefore, the upper limit value of the inclination angle θ2 of the second side wall portion 22 with respect to the plane perpendicular to the face surface 11 is determined to be 10 °, which is a critical value at which the spin number T is significantly increased in Table 5 and FIG. On the other hand, the lower limit value of the inclination angle θ2 of the second side wall portion 22 with respect to the surface perpendicular to the face surface 11 is determined to be 5 ° because the processing of the groove portion 20 is facilitated and manufacturing management is facilitated.

In all of the inventive examples C, D, E, H, M, P, Q, T, U, and V, the ratio A / (W1 + S) of the groove width W1 and the groove interval S to the groove cross-sectional area A is 0. It does not exceed 0030 inches (0.0762 mm ² / mm).

  Embodiment 2 of the present invention will be described below. Invention Example C is an embodiment of the present invention. Invention Examples C1, C2, and C3 are modifications of the present invention. Comparative examples A and B are comparative examples for the present invention. In addition, the same reference number is attached | subjected to the part which is the same or it corresponds, and the description may not be repeated.

  The relationship between the shape of the groove 20 of the iron golf club head and the spin number T will be described with reference to FIGS.

  Iron golf club heads were produced in which the values of the respective symbols of the groove portions 20 of the iron golf club heads shown in FIGS. .

  The loft angle of each iron golf club head is 56 °. As a material of each iron golf club head, JIS standard S25C was used. Each iron golf club head was Ni-Cr plated. Here, the Cr layer was 5 μm, and the Ni layer was 20 μm. On the iron golf club head, wet newspaper was pasted so as to cover the face surface 11 in order to reproduce a rough shot based on the R & A report.

  The spin performance of each iron golf club head was examined by a robot test. More specifically, the number of spins T was measured by hitting a ball with each iron golf club head using a mechanical golfer manufactured by Miyamae Co., Ltd. Specifically, the spin number T in a wet state of 30 years was measured. Each of the iron golf club heads hit five balls. In the column of the number of spins T in Table 6, the average value of the number of spins T of the balls hit by 5 balls each is described. The ball used Titleest Pro V1. The location of the hitting point was the score line center (the central portion in the longitudinal direction of the groove portion of the face surface), and was between the second groove portion from the top edge portion and the third groove portion from the sole portion. The spin number T of the ball was measured with a trajectory measuring instrument Trackman manufactured by Interactive Sports Games.

  8 and 9 are schematic sectional views of the groove portions 20 of Comparative Examples A and B in Table 6. FIG. 10 to 13 are schematic cross-sectional views of the groove portions 20 of Examples C, C1, C2, and C3 of the present invention shown in Table 6. In addition, in FIGS. 10-13, the connection part width W3 is the width | variety between the connection parts 25 of the groove part 20. FIG.

  The relationship between the shape of the groove 20 and the spin number T will be described with reference to Table 6 and FIG. As shown in Table 6, in Invention Examples C, C1, C2, C3 and Comparative Examples A and B, the groove width W1, the groove interval S, the bottom width W2, the groove depth D1, the first side wall depth D2, Second side wall portion depth D3, radius of curvature R, first side wall portion inclination angle θ1, second side wall portion inclination angle θ2, groove portion sectional area A, ratio of groove portion width W1 and groove portion interval S to groove portion sectional area A / ( W1 + S) is different.

  The spin numbers T (rpm) of Invention Examples C, C1, C2, and C3 are significantly higher than the spin numbers T of Comparative Examples A and B. Thereby, it turned out that spin number can be made high in this invention example C, C1, C2, C3.

In all of Invention Examples C, C1, C2, and C3, the ratio A / (W1 + S) of the groove width W1 and the groove interval S to the groove cross-sectional area A exceeds 0.0030 inches (0.0762 mm ² / mm). Not.

  In the above, the iron golf club head is plated, but the face surface may be shot blasted after the plating. Specifically, the score line is filled with wax. In this state, shot blasting is performed by applying sand to the face surface. Thus, the plating on the face surface can be removed while leaving the score line plating. Thereafter, the wax filled in the score line is dissolved and removed. As a result, the score line where plating remains is exposed. By removing the plating on the face surface by the shot blast process and leaving the plating on the score line, the visibility of the score line can be improved by comparing the colors of the face surface and the score line.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied particularly advantageously to an iron golf club head in which score lines are formed in the face portion.

  DESCRIPTION OF SYMBOLS 1 Iron golf club head, 10 Face part, 11 Face surface, 20 Groove part, 21 1st side wall part, 22 2nd side wall part, 23 Bottom part, 24 Connection part, 25 Connection part

Claims (2)

A face portion having a face surface;
A groove portion formed on the face portion and having a first side wall portion continuing to the face surface, a second side wall portion continuing to the first side wall portion, and a bottom portion continuing to the second side wall portion. And
The width of the groove measured by the 30 ° measurement method is 0.76 mm or more and 0.88 mm or less,
A roundness with a radius of curvature of 0.05 mm or more and 0.3 mm or less is given to a connection portion between the face surface and the first side wall portion,
A roundness is given to a connection portion between the first side wall and the second side wall,
The depth from the face surface to the bottom is 0.38 mm or more and 0.5 mm or less,
An inclination angle of the first side wall portion with respect to a surface perpendicular to the face surface is 36 ° or more and 40 ° or less,
An iron golf club head, wherein an inclination angle of the second side wall portion with respect to a plane perpendicular to the face surface is not less than 5 ° and not more than 10 °.   The iron golf club head according to claim 1, wherein the iron golf club head is made of a material including JIS standard S25C.

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