A golf club head has a hollow shell structure comprising: a main frame provided with three independent openings which are a front opening, a top opening and a bottom opening; a face plate covering the front opening; a crown plate covering the top opening; and a sole plate covering the bottom opening. The specific gravity Gc of the crown plate, the specific gravity Gf of the face plate and the specific gravity Gs of the sole plate are each smaller than the specific gravity Gm of the main frame. Preferably, the specific gravity Gc is smaller than the specific gravity Gf and smaller than the specific gravity Gs, and the main frame is made of a metal material. Therefore, the freedom of designing the center of gravity the club head can be increased.
1. A golf club head having a hollow shell structure comprising:
a main frame provided with three independent openings which are a front opening, a top opening and a bottom opening;
a face plate covering the front opening, the face plate comprising a face portion forming the clubface of the head and a turnback extending backwards from at least a part of the peripheral edge of the clubface;
a crown plate covering the top opening; and
a sole plate covering the bottom opening, wherein
the specific gravity Gm of the main frame, the specific gravity Gc of the crown plate, the specific gravity Gf of the face plate and the specific gravity Gs of the sole plate satisfy the following condition: Gm>Gf>Gs>Gc,
the specific gravity Gf is not less than 3.0 and not more than 5.0, and
the specific gravity Gm is not less than 4.0 and not more than 7.0, wherein
said main frame includes an upper frame between the front opening and the top opening which forms a front part of the crown portion extending in a heel-and-toe direction of the head, and
the minimum length of the upper frame in a back-front direction of the head is not less than 5 mm and not more than 30 mm.
2. The golf club head according to claim 1 , wherein the main frame is made of a metal material.
3. The golf club head according to claim 1 , wherein
the main frame, the face plate and the sole plate are each made of a metal material, and
the crown plate is made of a fiber reinforced resin.
4. The golf club head according to claim 1 , wherein the main frame, the face plate, the sole plate and the crown plate are each made of a metal material.
5. The golf club head according to claim 1 , wherein
the main frame is made of a titanium alloy
the face plate is made of a titanium alloy,
the crown plate is made of a magnesium alloy, and
the sole plate is made of an aluminum alloy.
6. The golf club head according to claim 1 , wherein
the main frame is made of a titanium alloy,
the face plate is made of a titanium alloy,
the crown plate is made of a fiber reinforced resin, and
the sole plate is made of an aluminum alloy.
7. The golf club head according to claim 1 , wherein
the main frame is made of a titanium alloy,
the face plate is made of a titanium alloy,
the crown plate is made of a magnesium alloy and
the sole plate is made of a titanium alloy.
8. The golf club head according to claim 1 , wherein
the main frame is made of a titanium alloy,
the face plate is made of a titanium alloy,
the crown plate is made of a fiber reinforced resin, and
the sole plate is made of a fiber reinforced resin.
9. The golf club head according to claim 1 , wherein said minimum length of the upper frame forming the front part of the crown portion is not less than 8 mm.
10. A golf club head having a hollow shell structure comprising:
a main frame provided with three independent openings which are a front opening, a top opening and a bottom opening;
a face plate covering the front opening, the face plate comprising a face portion forming the clubface of the head and a turnback extending backwards from at least a part of the peripheral edge of the clubface;
a crown plate covering the top opening; and
a sole plate covering the bottom opening, wherein
the specific gravity Gm of the main frame, the specific gravity Gc of the crown plate, the specific gravity Gf of the face plate and the specific gravity Gs of the sole plate satisfy the following condition: Gm>Gf>Gs>Gc,
the specific gravity Gf is not less than 3.0 and not more than 5.0, and
the specific gravity Gm is not less than 4.0 and not more than 7.0, wherein
said crown plate comprises: a generally-semicircular part forming an aft part of the crown portion; and a turndown extending downward from the arched rear edge of the aft part excepting the front edge, so that the crown plate covers said top opening which protrudes from the crown portion into the side portion, and the turndown forms an upper part of the side portion.
11. The golf club head according to claim 10 , wherein the main frame is made of a metal material.
12. The golf club head according to claim 10 , wherein
the main frame, the face plate and the sole plate are each made of a metal material, and
the crown plate is made of a fiber reinforced resin.
13. The golf club head according to claim 10 , wherein the main frame, the face plate, the sole plate and the crown plate are each made of a metal material.
14. The golf club head according to claim 10 , wherein
the main frame is made of a titanium alloy
the face plate is made of a titanium alloy,
the crown plate is made of a magnesium alloy, and
the sole plate is made of an aluminum alloy.
15. The golf club head according to claim 10 , wherein
the main frame is made of a titanium alloy,
the face plate is made of a titanium alloy,
the crown plate is made of a fiber reinforced resin, and
the sole plate is made of an aluminum alloy.
16. The golf club head according to claim 10 , wherein
the main frame is made of a titanium alloy,
the face plate is made of a titanium alloy,
the crown plate is made of a magnesium alloy and
the sole plate is made of a titanium alloy.
17. A golf club head having a hollow shell structure comprising:
a main frame provided with three independent openings which are a front opening, a top opening and a bottom opening;
a face plate covering the front opening, the face plate comprising a face portion forming the clubface of the head and a turnback extending backwards from at least a part of the peripheral edge of the clubface;
a crown plate covering the top opening; and
a sole plate covering the bottom opening, wherein
the specific gravity Gm of the main frame, the specific gravity Gc of the crown plate, the specific gravity Gf of the face plate and the specific gravity Gs of the sole plate satisfy the following condition: Gm>Gf>Gs>Gc,
the specific gravity Gf is not less than 3.0 and not more than 5.0, and
the specific gravity Gm is not less than 4.0 and not more than 7.0, wherein
said main frame includes an upper frame between the front opening and the top opening which forms a front part of the crown portion extending in a heel-and-toe direction of the head, and
the minimum length of the upper frame in a back-front direction of the head is not less than 5 mm and not more than 30 mm,
said crown plate comprises: a generally-semicircular part forming an aft part of the crown portion; and a turndown extending downward from the arched rear edge of the aft part excepting the front edge, so that the crown plate covers said top opening which opening protrudes from the crown portion into the side portion, and the turndown forms an upper part of the side portion.
18. The golf club head according to claim 17 , wherein said minimum length of the upper frame forming the front part of the crown portion is not less than 8 mm.
19. The golf club head according to claims 1 , 10 or 17 , which further comprises
a weight member having a specific gravity larger than that of the main frame, wherein
the rear face of the main frame is provided with a hole into which the weight member is fitted, and
the hole is provided along the edge of the opening with a small protrusion protruding over the peripheral edge of the outer end of the weight member so as to secure the weight member in the hole.