Bending of Alloy Steel Pipes and Copper Alloy Pipes by High Frequency Induction Heating Method

Abstract

Recently along the rapid growth of ship size, the use of large bore pipes have increased resulting in the increase in hot bending works and the use of bend pieces. This necessititated the rationalization and improvement in efficiency of the pipe bending method. Here high frequency induction heating pipe bending method was developed and applied mainly for bending of carbon steel pipes, which eliminated the use of bend pieces, shortened the time for bending method, and improved the quality of the bends produced. About the bending of alloy steel pipes and copper alloy pipes, various studies have been made. In high frequency induction heating pipe bending method water cooling treatment is applied immediately after bending in order to reduce the amount of deformation. Some alloy steel pipes which have high quench hardening properties are afraid to have bad effects at the bends by water cooling. But the effect by hardening due to water cooling for alloy steel pipe was hardly noticed in case of adoption of water-cooling system with a certain interval for air cooling. Mechanical properties of the alloy steel pipe bent by high frequency induction heating method compare favourably with those by the conventional hot bending works.