Patent attributes
A method for manufacturing an engine poppet valve comprising a valve head portion manufacturing operation in which hot forging is employed to form a stem/head intermediate product; a stepped stem portion manufacturing operation in which cold drawing is employed to cause a stepped stem portion comprising a first stem portion which has been made to be of decreased diameter, a step portion which has been formed by a stem member inlet surface, and a second stem portion in which there is absence of decrease in diameter and which is continuous by way of the step portion with the first stem portion to be formed from an intermediate stem portion; and a joining operation in which a stem end portion having a same outside diameter as the first stem portion is joined to a base end portion of the first stem portion.
