METHOD OF PRODUCING THIN WALLED CIRCULAR TUBE METAL MEMBER WITH CLOSED BOTTOM

摘要

A center hole is formed in a workpiece by cutting working performed along the center axis of the workpiece, which is a long round solid metal rod having a substantially constant diameter. Then, a hole forming step is performed in which a cooling hole (1c) is formed in the workpiece so that the workpiece has a bottom at its front end (1a). After that, a wall thinning step is performed in which the workpiece is subjected to cutting working to reduce the outer diameter on the front end (1a) side of the workpiece, and this reduces the wall thickness of the front end (1a) side. The steps enable wall thinning of a thin walled closed bottom circular tube metal member.