| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a hollow engine valve easily manufacturing the hollow engine valve achieving high strength and an improvement in weight reduction. <P>SOLUTION: In this method for manufacturing the hollow engine valve, a hollow shaft portion is sequentially inserted into a plurality of molded holes M1, M2', M(m-1), Mm, M(n-1), Mn having different hole shapes so that the sizes of the outside diameter and inside diameter of the hollow shaft portion in a semifinished product 10a are reduced in a stepwise fashion and also the length of the hollow shaft portion is extended in the stepwise fashion, and the hollow shaft portion is sequentially subjected to drawing, thereby molding the hollow shaft portion into a predetermined shape. The semifinished product 10a is subjected to heat treatment so that the hardness thereof is equal to or lower than a predetermined hardness, and the maximum thickness t2' between the hollow shaft portion and a valve umbrella portion connected to the lower end of the hollow shaft portion is formed to be thicker than the thickness t2 of the hollow shaft portion by means of the molded hole M2' of a die Di2' adjusted to have length L2' and maximum inside diameter D2'. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
