Method of making cooled valves for internal combustion engines and valves obtained thereby

摘要

The invention relates to a method of manufacturing cooled valves for internal combustion engines. From a first cylindrical billet is formed a valve blank by drilling an axial blind bore therein and machining an inner circumferential groove at the blind end portion of said bore. From a second cylindrical billet is machined a cylindrical rod-shaped core and at least two coolant feed and return flow channels, said core being inserted into the bore of said blank. Then said blank and said core are assembled by a hydrostatic extrusion.