Valve moving push rod for internal combustion engines and method of making the same

摘要

This invention is made with a view to increasing the fusing strength of an end piece in a valve moving push rod for internal combustion engines. The fusing part of the push rod according to the present invention consists of an alpha -martensite structure and a primary truestite structure in a cotransition boundary range of a segmental section formed into the hardened layer of the end piece from the fused boundary surface of the end piece with a tube end part and is provided with a tough mixed layer arcuated from the inside end part of the above mentioned fused boundary surface to the outside end part thereof. This mixed layer is obtained by reducing by a heat feeding means a quick temperature drop caused by the fusing part simultaneously with cutting off the fusing current in welding by electric resistance the end piece on the fixed side surface to the peripheral edge of the end port of a tube material. Such crack as is recognized in the fusing part of a conventional product is not recognized in a product obtained by reducing the quick cooling by this method.