Patent ID: 7775907

Claim:
A method for manufacturing a hollow golf club head comprising the steps of: preparing a main frame made of a metal material and provided with a top opening and a bottom opening, wherein the main frame is provided along the edge of the top opening with a rib so that the rib has an edge being flush with the edge of the top opening and protrudes from the outer surface of the crown portion around the top opening, and the step of preparing the main frame includes casting the main frame as a primary product not provided with the top opening, forming the top opening by means of lasering, and making said edge of the rib and the edge of the top opening by laser beam machining so that the edges become flush with each other; preparing a crown plate made of a metal material; preparing a sole plate made of a metal material, wherein the specific gravity SGs of the metal material of the sole plate is larger than the specific gravity SGm of the metal material of the main frame, and the proof stress YSs of the metal material of the sole plate is smaller than the proof stress YSm of the metal material of the main frame, and the sole plate comprises a main part which can almost fit to the bottom opening, and a protrusion formed at the peripheral edge of an inner surface of the main part so as to protrude from a part of said inner surface surrounded by the protrusion, and the step of preparing the sole plate includes providing slits for the protrusion which slits are arranged at intervals along the length of the protrusion; placing the sole plate in the bottom opening of the main frame so that the protrusion protrudes from the inner surface of an edge portion of the main frame around the bottom opening; inserting a die into the inside of the main frame through the top opening; caulking the sole plate by crushing the protrusion of the sole plate onto said edge portion around the bottom opening, by the use of the inserted die; placing the crown plate in the top opening of the main frame; and fixing the crown plate to the main frame by utilizing laser welding, wherein the laser beam is irradiated from the outside of the golf club head towards a micro gap between the edge of the crown plate and the edge of the top opening.