METHOD OF PRODUCING A HOLLOW POPPET VALVE AND AN APPARATUS THEREFOR

摘要

A method of producing a hollow valve comprises the step for forming material having a blind hole along its axis, the step for extruding the material in a shaping hole in a die downward and the step for lowering a lower part of a pin to an upper part of a smaller-diameter portion of the shaping hole to allow the material to plastically flow downward through a gap between the lower part of a pin and the smaller-diameter portion of the shaping hole thereby molding a primary intermediate of the hollow valve having a stem and a head at the upper end of the stem through which a hole is formed.