Method for bending a metal pipe.

摘要

This invention relates to hot bending a metal pipe to small radius, and especially relates to the method to keep heating temperature substantially constant while radius of bending is changed gradually from large to small at the start and from small to large at the end of bending in order to make change of pipe wall thickness very gentle and smooth.

In orderto change radius of bending graduallythe ratio of relative speed of heater to the pipe to angular speed of bending is changed gradually, and then the method to keep heating temperature constant is required,

Two methods are given for it, one is to keep ratio of relative speed of heater to the pipe to heating power supply constant and the other is to keep each of them constant separately.