A hollow golf club head is formed form a metal member with at least one opening. An FRP member made of a fiber reinforced resin is attached to the metal member to cover the opening. The metal member has at least one slit extending along at least a periphery of the opening and further includes an outer surface and an inner surface. The FRP member has a locking portion that enters into the slit from one side of the outer surface or the inner surface of the metal member and exiting from the other side so as to extend along a surface thereof.
1. A hollow golf club head comprising
a metal member made of at least one kind of metal material having at least one opening, and
a FRP member made of a fiber reinforced resin attached to the metal member so as to cover the opening, wherein
the metal member has at least one slit extending along the opening, in at least a part of a periphery of the opening, and
the FRP member has a locking portion entering into the slit from one side of an outer surface or an inner surface of the metal member and getting out of the other side so as to extend along a surface thereof.
2. The golf club head according to claim 1 , wherein the FRP member is made of a plurality of prepreg plies comprising at least one locking prepreg ply having reinforcing fibers which extend continuously from the one side to the other side of the metal member.
3. The golf club head according to claim 1 , wherein the metal member comprises a face portion whose front face defines a club face for striking a ball and a crown portion intersecting the club face at the upper edge thereof,
the opening is provided with the crown portion, and
the slit is provided between the opening and the upper edge of the club face.
4. The golf club head according to claim 3 , wherein in the metal member, a width Wu between the opening and the slit is from 1 to 30 mm,
a width Wm between the slit and the upper edge of the club face is from 1 to 30 mm,
and a ratio (Wm/Wu) of the widths is from 0.5 to 10.
5. The golf club head according to claim 1 , 2 or 3 , wherein
the slit has a first edge extending along a side of the opening and positioned at the one side of the metal member, and a second edge extending along a far side from the opening and positioned at the other side of the metal member,
and a difference of the height between the first edge and the second edge is from 0.1 to 2.0 mm.
6. The golf club head according to claim 1 , 2 or 3 , wherein
the slit has at least a corner portion which is in contact with the locking portion, and
the corner portion is rounded in a cross section perpendicular to a longitudinal direction of the slit.
7. The golf club head according to claim 2 , wherein the locking prepreg ply comprises at least one prepreg ply entering into the slit from the outer surface of the metal member and extending along the inner surface thereof.
8. The golf club head according to claim 7 , wherein the prepreg plies comprise at least one outer prepreg ply arranged in an outer side of the locking prepreg ply, and extending so as to cover the opening and the slit without entering into the slit.
9. The golf club head according to claim 2 , wherein the locking prepreg ply comprises at least one prepreg ply entering into the slit from the inner surface of the metal member and extending along the outer surface thereof.
10. The golf club head according to claim 9 , wherein the prepreg plies comprise at least one inner prepreg ply arranged in an inner side of the locking prepreg ply, and extending so as to cover the opening and the slit without entering into the slit.
11. The golf club head according to claim 1 , wherein the slit has a width in a range of from 0.5 to 10.0 mm.