PURPOSE: To make it unnecessary to execute after-working of a cam piece by executing a surface treatment such as quenching and grinding, etc. to a cam surface of the cam piece of a steel material or a sintered material, and thereafter, fitting it externally to a pipe material, caulking the pipe material from the inside surface, and fixing the cam piece to the pipe material.

CONSTITUTION: A cam piece is formed by forging a steel material, and becomes a finished product by performing a surface treatment such as induction hardening and grinding, etc. to its cam surface, and thereafter, fitted externally to a pipe material 2. Subsequently, when the pipe material 2 is caulked from the inside surface side, and the outside surface of the pipe material 2 is welded by pressure to a recessed part 3B of the inside peripheral surface of a pipe fitting hole 3A of the cam piece 3, the cam piece is formed as one body with the pipe material 2. Accordingly, as for the cam piece 3, working such as a formation of the cam surface, quenching of the cam surface, grinding, etc. can be performed in a stage of a single item, therefore, its after-working becomes unnecessary. Also, many cam pieces 3 can be worked in a lump. Furthermore, said working is executed in the pre-stage for fixing it to the pipe material 2, therefore, the work can be executed easily.