Golf club head
A head 2 has a face line 8 having a depth of D1 (mm). In a section line of a surface of the face line 8 , a boundary between a land area LA and the face line 8 is defined as a point Pa; a point of which a depth is [D¼] (mm) is defined as a point Pb; a point of which a depth is [D½] (mm) is defined as a point Pc; a point of which a depth is [(D1)×(¾)] (mm) is defined as a point Pd; a radius of a circle CL 1 passing through three points of the point Pa, the point Pb, and the point Pc is defined as R 3 (mm); a straight line passing through the point Pc and the point Pd is defined as a straight line Lcd; a straight line perpendicular to the land area LA is defined as a straight line Lp; and an angle between the straight line Lcd and the straight line Lp is defined as θm. At that time, the radius R 3 is 0.01 (mm) or greater and 0.10 (mm) or less, and the angle θm is 40 degrees or greater and 70 degrees or less.
1. A golf club head comprising a face line having a depth of D1 (mm) and a land area,
wherein when a boundary between the land area and the face line in a section line of a surface of the face line is defined as a point Pa; a point of which a depth is [D¼] (mm) is defined as a point Pb; a point of which a depth is [D½] (mm) is defined as a point Pc; a point of which a depth is [(D1)×(¾)] (mm) is defined as a point Pd; a radius of a circle CL 1 passing through three points of the point Pa, the point Pb, and the point Pc is defined as R 3 (mm); a straight line passing through the point Pc and the point Pd is defined as a straight line Lcd; a straight line perpendicular to the land area is defined as a straight line Lp; and an angle between the straight line Lcd and the straight line Lp is defined as θm,
the radius R 3 is 0.01 (mm) or greater and 0.10 (mm) or less, and the angle θm is 40 degrees or greater and 70 degrees or less.
2. The golf club head according to claim 1 , wherein the section line is smoothly continuously formed between the point Pa and the point Pd.
3. The golf club head according to claim 1 , wherein a maximum value Zm of a deviation distance between the section line of the point Pa to the point Pc and the circle CL 1 is equal to or less than 0.05 mm.
4. The golf club head according to claim 1 , wherein the radius R 3 is equal to or less than 0.090 (mm).
5. The golf club head according to claim 1 , wherein the radius R 3 is equal to or less than 0.080 (mm).
6. The golf club head according to claim 1 , wherein an angle θ 1 between a tangent at the point Pa and the land area is equal to or less than 30 degrees.
7. The golf club head according to claim 1 , wherein an angle θ 2 between a tangent Le 1 of the circle CL 1 at the point Pa and the land area LA is equal to or less than 30 degrees.
8. The golf club head according to claim 1 , wherein a curvature radius Ra at each of points between the point Pa and the point Pc is constant.
9. The golf club head according to claim 1 , wherein a curvature radius Ra at each of points between the point Pa and the point Pc is not constant.
10. The golf club head according to claim 1 , wherein a straight line portion is included between the point Pa and the point Pc.
11. The golf club head according to claim 1 , wherein only a curved line is included between the point Pa and the point Pc.
12. The golf club head according to claim 1 , wherein a curvature radius Ra at each of points between the point Pb and the point Pc is constant.
13. The golf club head according to claim 1 , wherein a curvature radius Ra at each of points between the point Pb and the point Pc is not constant.
14. The golf club head according to claim 1 , wherein a straight line portion is included between the point Pb and the point Pc.
15. The golf club head according to claim 1 , wherein a curvature radius Ra at each of points between the point Pc and the point Pd is constant.
16. The golf club head according to claim 1 , wherein a straight line portion is included between the point Pc and the point Pd.
17. The golf club head according to claim 1 , wherein only a straight line is included between the point Pc and the point Pd.
18. The golf club head according to claim 1 , wherein at least one of a straight line and/or a curved line is smoothly continuously formed between the point Pa and the point Pd.
19. The golf club head according to claim 1 , wherein a groove width W 1 is 0.20 mm or greater and 0.889 mm or less.
20. The golf club head according to claim 1 , wherein the face line is formed using a cutter rotated about an axis line z 1 ;
a cutting surface of the cutter has a conical surface; and
an angle θg 1 between the axis line z 1 and the conical surface is 40 degrees or greater and 70 degrees or less.
21. The golf club head according to claim 1 , wherein the groove angle θm (degree) and the radius R 3 (mm) satisfy the following formula (F1):
R 3≧−0.002 ×θm+ 0.14 (F1).
22. The golf club head according to claim 1 , wherein the groove angle θm (degree) and the radius R 3 (mm) satisfy the following formula (F2):
R 3≧−0.002 ×θm+ 0.16 (F2).
23. The golf club head according to claim 1 , wherein the groove angle θm (degree) and the radius R 3 (mm) satisfy the following formula (F3):
R 3≦−0.002 ×θm+ 0.20 (F3).
24. The golf club head according to claim 1 , wherein the groove angle θm (degree) and the radius R 3 (mm) satisfy the following formula (F4):
R 3≦−0.002 ×θm+ 0.18 (F4).