Regular Article

Increasing bending angle in thick-walled pipes with wide heating

¹ Department of Mechanical and Energy Engineering, Shahid Beheshti University, Tehran, Iran
² Faculty of Mechanical and Energy Engineering, Shahid Beheshti University, Tehran, Iran

^* e-mail: e_moussavi@sbu.ac.ir

Received: 6 April 2019
Accepted: 6 September 2019

Abstract

The spot heating of a metal part leads to many small deformations. The applications of this method are straightening the bridge parts, turbo-machinery shafts, and so forth. The movement of the heat source on a given path (line heating) leads to an increase in the deformation and the possibility of creating complex bends. However, it is complicated to predict and control the path and velocity of the heat source as well as determining the heat intensity. In the pipes, this method requires simultaneous control over the two torches on both sides of the pipe. The present study aims at investigating the mechanism of deformation and increasing the bending angle in thick pipes by means of a simple heating method. At first, the maximum bending in heating a large circular zone (entitled “wide heating”) is obtained by simulating the process using finite element method and optimizing it applying the genetic aggregation algorithm. Then, a new method for simultaneous heating within two zones is introduced. The interaction between two zones leads to the development of the shortening mechanism in the pipe wall and a significant increase in the bending angle. In this method, there is no need to move the torch where the temperature is controlled more accurately. To evaluate the finite element model, several pipe heating tests are performed with their results being agreed well with the simulation results.