Computer Numerical Simulation And Optimization Of Tube—Bending Process Using The Local Induction Heating

As a kind of important plastic forming method, tube bending process plays an important role in the field of oil and gas transportation, aerospace, engineering machinery, pipeline engineering and so on. With the development of West-East Gas Pipeline Project, the demand for large-diameter high-strength thin-walled tube is growing, also put forward higher requirements on the pipe processing technology. The TPIH(Tube-bending Proeess Using Local Induction Heating) is easy to appear the quality defects such as the wall-thickness extreme thinning, wrinkling and distortion of the bending section, so the research of technical parameters and temperature field distribution in TPIH is of great significance for the practical production.This paper establishes a simplified model of TPIH, the stress state is analyzed under some simplified conditions, obtains the formulas of pushing force and counterforce of supporting wheels, analyzes the phenomenon of bending section flattening. According to the process involves multi physical field coupling problem, puts forward a applicable method of finite element simulation. The induction heating in the motion of the workpiece is realized by using dynamic loading. The simulation of continuous induction heating and cooling process of tube blank is realized by using ANSYS/Multiphysics module. The finite element simulation was carried out for the induction heating condition with different induction coil width and cooling distance, and the axial temperature distribution of the pipe under different conditions was obtained.The thermal simulation experiment of X80 pipeline steel was carried out by using Gleeble – 3500, the mechanical parameters of materials were obtained according to the stress-strain curves under different temperatures. The TPIH of finite element analysis was carried out using LS-DYNA, solve the thermal-structure coupling problem in TPIH, the plastic deformation of the pipe in steady temperature field is realized. The pipe wall thickness variation, ovality, deflection as the main criterion, the influences of the process parameters such as the advancing velocity, the relative bending radius, the relative thickness and the position of the supporting wheels on the forming quality of the tube were studied.Based on the temperature field simulation results, the plastic forming process of different temperature distribution is simulated. By analyzing the forming quality of the pipe after bending, the circumferential uniform cooling condition has obvious improvement effect on the wall-thickness extreme thinning and thickening, ovality of the bending section and displacement of the neutral layer, the ideal temperature zone width is obtained by comparing the forming quality of the pipe. Further optimize the circumferential differential cooling, the four zone differential cooling is ideal for the ovality control, the differential cooling of internal and external cooling is ideal for the thinning rate control and the reasonable range of the two kinds of cooling methods were studied.