To provide a method of efficiently manufacturing a different diameter steel tube which is different in the diameter and plate thickness in the axial direction by performing deforming work for reducing the diameter by reducing a load imposed on a die when performing core drawing by single pass.
When manufacturing the different diameter steel tube which is provided with a large diameter part, a small diameter part and a tapered part for connecting the small diameter part to the large diameter part from one steel tube by using a die 7 having a hole whose inside diameter is smaller than the outside diameter of the tube stock 8 and a plug 9 for controlling the plate thickness by inserting it into the inside of the steel tube by the core drawing by drawing force from the front, the core drawing is performed by adding tensile force from the rear.
KANO SHINOBU
KUROBE ATSUSHI
| JPS589712A | 1983-01-20 | |||
| JPS5950913A | 1984-03-24 |
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