The Optimization of Welding Spots’ Arrangement in A-Pillar Patchwork Blank Hot Stamping

Abstract

With increasingly severe environmental problems, energy saving and environmental protection have become two important issues to be solved in the automobile industry. Patchwork blank hot-stamping technology can be used to obtain light-weight and high-strength parts and is thus increasingly used in the manufacture of autobody parts. Because the main blank and the patched blank need to be connected through spot welding before forming, the welding spots’ arrangement has a great influence on the formability of the part. In this study, a thermal–mechanical coupling finite element analysis model of A-pillar patchwork blanks was established. With the thickness of the patched blank, the distance between the welding spot and the external contour of the patched blank, and the number of welding spots as optimization variables, together with the maximum thinning rate and the maximum welding spot force as objectives, the influence of welding spot arrangement on forming quality was analyzed, and the welding spots’ arrangement was optimized using a central composite design (CCD), the response surface method (RSM), and the genetic algorithm (GA). The results showed that when the initial welding spot was located close to the contour of the patched blank, the bending moment was greater when the weld spot passed through the die corner, leading to the rupture of the welding spot or its surrounding base material due to the greater thinning rate. When the patched blank was thicker than the main blank, the main blank cracked during the forming process due to a greater increase in the thinning rate. The optimal solution of the weld spot arrangement on the A-pillar patchwork blanks was a 1.2 mm thick main blank, 0.8 mm thick patched blank, a distance of 29 mm between the weld spot and the contour line of the patched blank, and 16 weld spots. Hot-stamping experiments were conducted using the optimized weld spots’ arrangement, and high-quality parts were obtained.

Buckling Defect Optimization of Constrained Ring Rolling of Thin-Walled Conical Rings with Inner High Ribs Combining Response Surface Method with FEM

“…Li et al used the thickness of the patched blank, the distance between the welding spot, the external contour of the patched blank, and the number of welding spots as optimization variables, and analyzed the influence of the distribution of welding spots on the quality of welding. The optimized welding spot arrangement method was used to carry out the process experiment, and the parts with a high forming quality were obtained [23]. Combining RSM and FEM, Hu et al studied the effects of the friction factor, the fillet radius of the cavity, and the diameter of the rolling roll on the heights of the longitudinal and transverse ribs and obtained the optimal process combination [24].…”