| 摘要 |
PURPOSE: To easily produce a valve having a large internal volume and high strength by constituting the valve of a tubular valve shank, which has a large diameter shank part arranged to a valve side and is separately produced, and a heat resistant valve body and forming to a prescribed shape. CONSTITUTION: A tubular base material 1 having an outer diameter D0 , for forming a valve shank 3, is reduced to a desired outer diameter D1 of the valve shank 3 by a proper tool 2. This is done by cold working, e.g. a round bar rolling process. A transitional range between the reduced valve shank 3 and the base material 1 is formed curved as the shank part of a large diameter, at last, the valve shank 3, in a large diameter shank part, is cut at a place corresponding to a diameter of a joining place between the valve body and the valve shank 3. The valve body 10 is joined to a joining place of a valve back part e.g. by laser beam welding, a plug is inserted to a valve shank upper end and welded at a prescribed place. |
