To provide a bending method of an inexpensive thin wall pipe having high work accuracy or a metal pipe capable of small bending work of a flexural center radius, for pressing a bending part by four-point support, by using a bending metal mold, a cushion metal mold, and a movable roll.
A processed metal pipe is placed on a cushion metal mold and a pair of movable rolls arranged on its both sides, and a bending work is executed by pressing the bending metal mold to the processed metal pipe from just above the cushion metal mold. Tension is generated in a bending part of the metal pipe from frictional force F1 and F2 of a pipe outer surface by a cushion load and a roll load, and the bending work is executed while relieving compressive stress of a bending center part, and occurrence of buckling can be restrained thereby.
OKUSU HIROSHI
NISHIO KATSUHIDE
| JPH0351917U | 1991-05-21 | |||
| JP2007307615A | 2007-11-29 | |||
| JPS58185324U | 1983-12-09 | |||
| JPH07328726A | 1995-12-19 |
| US6523388B1 | 2003-02-25 |