To obtain a bent steel pipe in which rapture on the outside of a bend is prevented and also flattening is suppressed even when a thin wall steel pipe is used as a base stock.
In this method of bending a steel pipe to be worked, the steel pipe to be worked is pulled along a rotatable bending die on which a circular-arcuate part for bending/guiding is formed with a clamp and bent by rotating integrally with the bending die while holding the steel pipe to be worked with a wiper and a side booster, and incompressible fluid is given into the steel pipe to be worked at low water pressure when performing the bending work and, after finishing the bending work, flattening formed during the bending work is corrected by forcing the incompressible fluid the pressure of which is higher than that during the bending work.
NISHIO KATSUHIDE
KUROBE ATSUSHI
| JPS6334519U | 1988-03-05 | |||
| JPS5577934A | 1980-06-12 |