| 摘要 |
PURPOSE:To form an increased thickness part having a prescribed thick wall shape in upsetting of a tubular body by calculating beforehand the volume of a standard thickness increase in the increased thickness part at the end of the tubular body and charging the end of the tubular body corresponding to the volume thereof into the upsetting region of a split die. CONSTITUTION:The wall thickness of a tubular body is measured with an ultrasonic wall thickness gage 32 and the wall thickness is integrated to the wall thickness in the circumferential and axial directions of the tubular body in an arithmetic device 33 and the length at which the volume from the top end of the tubular body attains equal to the volume of a standard thickness increase is determined. The tubular bodies 11, 12 which are measured of the lengths L1, L2 thereof are charged by the lengths L1, L2 into the upsetting regions 22, 23 of a split die, and are upset by the upsetting part 27 of a mandrel bar 25 and the upsetting part 28 of a mandrel bar 26 advancing, at the same stroke, into the respective upsetting regions 22, 23. |
