Method for manufacturing golf club head
View Patent ↗A method for manufacturing a golf club head composed of a metal main body and a non-flat metal face member which are welded each other is disclosed. In order to make the non-flat metal face member, an in-process face material is cut out from a rolled metal plate having a constant thickness. And a turnback is formed around the in-process face material by press working. Before making the press working, the region of the in-process face material corresponding to the turnback is decreased in the thickness by a cutting work.
1. A method for manufacturing a golf club head comprising:
a step of preparing a non-flat metal face member which comprises a main portion forming at least a part of a club face for striking a ball and a turnback extending backward from at least a part of the peripheral edge of the club face;
a step of preparing a metal head main body; and
a step of welding the non-flat metal face member to the metal head main body, wherein
the step of preparing said non-flat metal face member comprises:
a process (a) in which a rolled metal plate having a constant thickness is prepared;
a process (b) in which an in-process face material is cut out from the rolled metal plate after the process (a);
a process (c) in which the face member is prepared by forming the turnback by subjecting the in-process face material to a press working after the process (b);
a process (d) in which, in the outer surface of a corresponding-to-turnback region corresponding to the turnback,
an inclined surface inclined to the inner surface of corresponding-to-turnback region towards the peripheral edge of corresponding-to-turnback region is formed
by a cutting work carried out before the process (c) in a state of the in-process face material or in a state of the rolled metal plate so that the thickness of the corresponding-to-turnback region is continuously decreased towards the peripheral edge of the corresponding-to-turnback region.
2. The method for manufacturing a golf club head according to claim 1 , wherein
the turnback is formed along the entire circumference of the main portion.
3. The method for manufacturing a golf club head according to claim 2 , wherein
the turnback is made up of a crown-side turnback, a sole-side turnback, a toe-side turnback and a heel-side turnback, and
the size of the turnback in a front to back direction has a maximum value in the crown-side turnback and sole-side turnback, and
in the toe-side turnback and heel-side turnback, the size is not more than 50% of said maximum value.
4. The method for manufacturing a golf club head according to claim 1 , 2 or 3 , wherein
the rolled metal plate having the constant thickness, has a strength anisotropy such that the maximum tensile strength measured in a certain direction is not less than 1.06 times the tensile strength measured in the normal direction to said certain direction, and
in the process (b), the in-process face material is cut out from the rolled metal plate so that the angle between said certain direction and the up-and-down direction of the club face becomes not more than 45 degrees.
5. The method for manufacturing a golf club head according to claim 1 , 2 or 3 , wherein
the rolled metal plate is made of a titanium alloy having alpha phase, or a stainless steel or a maraging steel.
6. The method for manufacturing a golf club head according to claim 1 , wherein
the volume of the golf club head is not less than 400 cc and not more than 470 cc.
7. The method for manufacturing a golf club head according to claim 1 , wherein
the mass of the golf club head is not less than 180 grams and not more than 210 grams.
8. The method for manufacturing a golf club head according to claim 1 , wherein
the maximum thickness (t 2 ) of the turnback excluding a possible weld bead is not more than 2.50 mm and not less than 1.70 mm.
9. The method for manufacturing a golf club head according to claim 1 , wherein
the turnback is made up of a crown-side turnback, a sole-side turnback, a toe-side turnback and a heel-side turnback, and
the size of the turnback in a front to back direction has a maximum value in the crown-side turnback and sole-side turnback, and
in the intersecting part between the crown-side turnback and toe-side turnback and also in the intersecting part between the crown-side turnback and heel-side turnback, the size is not more than 50% of said maximum value.
10. The method for manufacturing a golf club head according to claim 1 , wherein
the size of the turnback in the front-back direction is not less than 3.0 mm and not more than 13.0 mm.
11. The method for manufacturing a golf club head according to claim 1 , wherein
the process (d) is carried out in the state of the rolled metal plate after the process (a) and before the process (b).
12. The method for manufacturing a golf club head according to claim 1 , wherein
by the cutting work in the process (d), each of the inner surface and outer surface of the corresponding-to-turnback region is provided with the inclined surface.
13. The method for manufacturing a golf club head according to claim 1 , wherein
the thickness (t 4 ) of the peripheral edge portion of the corresponding-to-turnback region is not less than 0.80 mm and not more than 1.60 mm.
14. The method for manufacturing a golf club head according to claim 1 , wherein
the quotient (t 2 −t 4 )/(Ls) of the difference (t 2 −t 4 ) between the thickness (t 2 ) of the corresponding-to-turnback region at its the base and the thickness (t 4 ) of the corresponding-to-turnback region at its peripheral edge, divided by the width (Ls) of the corresponding-to-turnback region is not less than 0.03 and not more than 0.35.
15. The method for manufacturing a golf club head according to claim 1 , wherein
the cutting depth (d 1 ) of the inclined surface formed on the outer surface of the corresponding-to-turnback region is not less than 0.15 mm and not more than 0.50 mm.
16. The method for manufacturing a golf club head according to claim 1 , wherein
the ratio (d 1 )/(Ls) of the cutting depth (d 1 ) of the inclined surface formed on the outer surface of the corresponding-to-turnback region to the width (Ls) of the corresponding-to-turnback region is not less than 0.015 and less than 0.090.
17. The method for manufacturing a golf club head according to claim 1 , wherein
the cutting depth of the inclined surface formed on the inner surface of the corresponding-to-turnback region is not less than 0.10 mm and not more than 0.30 mm.
18. The method for manufacturing a golf club head according to claim 1 , wherein
the cutting depth (d 1 ) of the inclined surface formed on the outer surface of the corresponding-to-turnback region is not less than 0.15 mm and not more than 0.50 mm,
the cutting depth (d 2 ) of the inclined surface formed on the inner surface of the corresponding-to-turnback region is not less than 0.10 mm and not more than 0.30 mm, and
the ratio (d 1 )/(d 2 ) is not less than 2.0 and not more than 5.0.
19. The method for manufacturing a golf club head according to claim 1 , wherein
the rolled metal plate is a unidirectionally rolled metal plate.
20. The method for manufacturing a golf club head according to claim 1 , wherein
the press working in the process (c) is carried out by the use of a pair of drawing dies and, wherein the positive drawing die is provided with a non-flat molding surface corresponding to the surface of the thick central region, thin surrounding region and transitional region of the in-process face material.
21. The method for manufacturing a golf club head according to claim 1 , wherein
the step of preparing said non-flat metal face member further comprises:
a process for giving a face bulge and/or a face roll to the main portion of the face member which is incorporated in the press working of the process (c).