| 摘要 |
A method of forming a screw thread on one portion of a crankshaft and the like wherein the one portion of the shaft is worked on to provide thereto a diameter of a value greater than the value of the diameter of the one portion of the shaft before it is subjected to roll threading plus the value of the thickness of a hard, thin surface layer expected to be formed by carburizing on the whole of the shaft. Then, carburizing is performed to form the hard, thin surface layer on the whole of the shaft. Thereafter, the one portion of the shaft is subjected to grinding or machining to remove the hard, thin surface layer therefrom to reduce the diameter of the one portion of the shaft to a level conforming to the diameter thereof before roll threading is performed on the one portion of the shaft, and roll threading is performed on the one portion of the shaft from which the hard, thin surface layer is removed, to provide the shaft with a threaded portion. |
