| 摘要 |
PROBLEM TO BE SOLVED: To improve joining strength by friction pressure welding of a valve body and a plug of a hollow engine valve, and to reduce the manufacturing cost.SOLUTION: A hollow engine valve includes a valve body 10 which has a valve shaft part 14 and a valve head part 16 and has a hollow hole 18 axially extended from a head front side of the valve head part 16 and having a spot facing recession 20, and a plug 12 which is friction pressure welded to a bottom surface 20a of the recession 20 of the hollow hole 18 of the valve body 10. When friction pressure welding of the plug 12 to the valve body 10 is performed, joining surfaces (20a, 12a) of the valve body 10 and the plug 12 are orthogonal to an axis of the hollow hole 18, and a space 22 for storing an outer burr generated by friction pressure welding is formed on an outer peripheral side of the joining surfaces (20a, 12a) of the valve body 10 and the plug 12. |
