| 摘要 |
<p>A method for manufacturing a hollow engine valve, capable of simplifying the manufacturing process and reducing the manufacturing cost. A method for manufacturing a hollow engine valve is configured in such a manner that, in order to form the hollow shaft section of a half-finished product (1a) into a predetermined shape, the hollow shaft section is inserted in sequence into die holes (M1, M2, M (m-1), Mm, M (n-1), Mn'), which have different hole shapes, and subjected in sequence to drawing so as to reduce the outer diameter and the inner diameter of the hollow shaft section in stages and so as to stretch the length of the hollow shaft section in stages. In the method, the half-finished product (1a) is subjected to heat treatment so that the hardness thereof is lower than or equal to a predetermined level, a shaft end sealing section (15) is formed by increasing the wall thickness of the opening end of the hollow shaft section (12) toward the inside of the opening end by the die hole (Mn') of a die (Din'), the die hole (Mn') having an inner diameter adjusted to d2', and the gap in the shaft end sealing section (15) is welded.</p> |
