The Controling Of Weld-line Movement And Springback In Cap-shape Tailor-welded Blanks Bending

Faced with such problems as environmental pollution and energy shortage in the world, to realize auto lightweight becomes the inevitable trend of auto industry development. If cars are assemblied with parts made by tailor-welded blanks, the vehicle weight and production cost can be largely reduced, so the welding plate stamping technology is more and more widely used in the automotive industry. Because of the difference of material, thickness, the influence of weld-line and the heat affected zone and other factors, the weld-line movement and springback defects will appear in the forming process of tailor-welded blanks, thus the size precision of bending parts and the quality of the products will be largely reduced, so it is important and significant to make the research of weld-line movement and springback.In welding plate bending parts, the cap-shape is very tipical. For the effective controling of the weld-line movement and springback in tailor-welded blanks’ bending, In this paper, the transverse weld seam welding plate hat shapes and longitudinal weld seam welding plate hat shapes will be researched. First of all, their reasonable finite element model is established, and their forming and springback process are simulated by using the finite element software Dynaform, and mainly analyzes the influence of blank holder force, the coefficient of friction, punch radius, die radius and thickness ratio on the weld-line movement and springback. In addition,the transverse and longitudinal welding plate which the weld-line is not in the middle(weld bias towards thick or thin side) was studied, and the influence of blank holder force, material thickness ratio and weld position to its forming is considered.In this paper, as one of the main influence factors,the influence of blank holder force to weld-line movement and springback has been researched in detail when the thin side blank holder force does not equal the thick side blank holder force. Based on the above research, the blank holder force changing with time control scheme is proposed, and make a main research on the influence of initial blank holder force and the location of the blank holder force changing with punch trip as well as the high blank holder force to the weld-line movement and springback. Based on the above research, finally it is concluded that applying reasonable blank holder force(the combination of the thin side and thick side) to ensure the less weld moving at the beginning of the forming, then increase the thin side blank holder force and the thick side blank holder force at the same time to reduce springback when the punch reach a certain value.