To provide a valve seat the material cost of which can be saved, since the volume of a valve abutting layer made of an expensive material is small.
The top surface 13a of a lower second punch 13 is situated in the upper part than the bottom end position of the taper surface 12a of a lower first punch 12 and first material powder P1 forming the taper part of the valve seat is charged into a first charging space S1 formed on the lower first punch 12. Next, the lower second punch 13 is lowered, its top surface 13a is made not higher than the bottom end position of the taper surface 12a and part of the material powder P1 on the lower first punch 12 is slid along the taper surface 12a of the lower first punch 12 and moved on the lower second punch 13. Further, second material powder P2 is charged on this first material powder P1. The material powder charged into the charging space is leveled by being made to coincide with the top surfaces of a die 10 and a core rod 11. An upper punch 14 is lowered and fitted between the die 10 and the core rod 11 and the material powder P1, P2 in the charging space is compressed and formed.
HORIKAWA YOSHIHIRO
Tadashi Takahashi
Masakazu Aoyama
Akihiko Eguchi
Hideyuki Sugiura
Yasuhiko Murayama
Noriko Yanai