Method of and apparatus for forming a hollow step profiled shaft

摘要

A hollow step-profiled shaft such as a cam shaft that is high in accuracy and excellent in productivity and requires little post-machining is being formed. To this end, a hollow stepped shaft 8 having its axis and large diameter portions 9 a- 12 b intermediate axially between its ends is formed by a forming process in which each large diameter portion of the shaft is compressed with forming dies 32 a- 32 d from at least three different directions approximately simultaneously towards the axis to shape the large diameter portion with a profile such as to conform to contours 38 a- 38 d of a cavity 38 formed in a region of tips of the forming dies 32 a- 32 d.