Hot bending method for steel tube

TLDR: In this article, a push roll system is used to bend a steel tube without leaving a sensitization area by heating not only a bending part of the steel tube but also the straight tube part of an unbending part at a temperature higher than the solid solution temperature.

Abstract: PURPOSE:To perform high frequency bending and to accurately bend a steel tube without leaving a sensitization area by heating not only a bending part of the steel tube but also the straight tube part of an unbending part at a temperature higher than the solid solution temperature. CONSTITUTION:In a push roll system, a high frequency induction heating is performed by heating coil 7 to a stainless steel tube 2 over the solid solution temperature. When a drive device 4 is advanced under this state, the heating area of the stainless steel tube 2 is moved continuously and heated. Further, since cooling nozzles are equipped on the heating coils 7, the heating area moves to the cooling area with the advance of the tube and is quenches. Then, the tube in the bending is sent under the same heating and cooling conditions as under the straight heating and is bent by giving the bending moment at right angles to the advancing direction through a push roller 3 laid before the heating coils. The bending angle and bending radius are determined by controlling the position of the push roller 3 by a detected device set.