Multi-objective Optimization of Medium Frequency Induction Heating Process for Large Diameter Pipe Bending

Medium frequency induction heating for large diameter pipe bending is an advanced technique that has been widely used. However, the thickness control of outer wall and inner wall of pipe is still difficult in the actual production: outer wall tends to be thinner and inner wall tends to be thicker. Therefore, it is necessary to optimize the process parameters of bending. Combined central composite experimental design and a proper selection of design parameters sample, an accurate response surface model was built in order to decrease ovality, thickness reduction ratio and forming load. The response value of objective function was analyzed; and important influence factors for system stability were found, i.e heating temperature, heating width and advance speed. The results indicate that the optimal value range were heating temperature of outer wall t=1030∼1070 °C, while advance speed v=0.3∼0.4 mm/sec. Practical results from multi-objective optimization could achieve qualified products.