PRODUCTION OF WORM SHAFT FOR POWER STEERING DEVICE

PURPOSE:To simplify production stage and to eliminate the rotating error of a rotation control valve by forming simultaneously, by plastic working, the groove of the valve sleeve of the rotation control valve and the rugged parts on the sleeve side constituting a fail-safe in the stage of producing a worm shaft. CONSTITUTION:A valve sleeve 16 of a rotation control valve which supplies and discharges a pressure fluid together with a valve rotor 15 is formed on a worm shaft 10 and further rugged parts 25, 26 constituting a fail-safe 24 by engaging at a required space with the projecting part 27 on the outside circumference of an input shaft 12 are provided. A round bar blank material for the shaft 10 is preformed by means of a punch and a die and thereafter the outside shape of the shaft 10, the sleeve groove 19 on the inside circumferential surface, the rugged parts 25, 26 of the fail-safe and the inside circumferential side in the increased diameter part 20 to be fitted with a stop-off ring 23 are simultaneously formed with plastic deformation by using a finishing die 35, punch 36 and supporting material 37. The simplification in the production stage of the worm shaft is thus made possible and the error in the rotating direction of the control valve is eliminated.