Method of producing a shaft from a piece of tubing, apparatus for making a shaft from a piece of tubing and camshaft produced from a piece of tubing

摘要

A method and apparatus for producing a shaft from a piece of tubing having at least one bulging portion. The method enables shafts with bulging portions to be cheaply and practicably produced. The piece of tubing bears radially against a portion adjoining the zone of the bulging portion to be produced. The piece of tubing is subjected to internal pressure which is maintained throughout the entire molding operation. The piece of tubing is acted upon by an axially operative compressive force co-operating with the internal pressure so that a portion of tubing adjoining the radially borne portion is upset so that the external diameter of the upset piece of tubing is larger than the external diameter on the unupset piece of tubing. A molding tool, having a hollow portion corresponding to the final shape of the bulging portion to be produced, is then applied to the upset piece of tubing. The bulging portion is formed by the application of radially operative compressive forces by means of the molding tool.