예열된 U-굽힘 고장력강의 롤 성형에 대한 매개변수 연구

Abstract

With the development of the automotive industry, the automotive industry put forward a new appeal of safety, environmental protection and energy saving. The emergence of high-strength steel meets the requirement of those highly impact factors. High strength steel can achieve the same strength as well as effectively reduce the material thickness. High strength steel forming technique has been widely recognized on the market, so the insiders pay close attention to this technology. However, with the increase of strength, the elongation and plastic property of the sheet have been reduced, the forming performance decreased and more difficult to make deformation at room temperature. At the same time, because of the work hardening, the product is easy to crack and have a large spring back angle. To solve this problem, some researchers come up a method to apply the heating process to the sheet before the forming process. With the pre-heating process, the microstructure of the steel has been changed, thereby affecting the phatic property and the elongation of the sheet, reduce the deformation resistance and make the sheet easier to deform. Roll forming is a kind of plastic forming process in which a steel strip is bent by several sets of rolls gradually into the desired shape. The products are cold roll forming steels with various sections. Roll forming is one of the most widely used processes in the world for forming metal. Roll forming is a complex deformation process, which involves large displacement, finite strain and the problems of contact and friction between strip and rolls. This process exhibits obvious geometry, physical and boundary nonliterary. The complex processes contain many aspects such as geometry, kinematics and dynamics, etc. The forming process involves not only transverse bending, but also other additional deformations. In this paper, we have set up two kinds of roll forming models with the high strength steel using ABAQUS software which are cold roll forming and preheated roll forming. The sheets in both two models have been measured the contour bow defect of displacement and the stress are used to analysis the deformation of the sheet. The spring back also has been developed in the two simulation. At last, experiments were carried out to verify the validity of the proposed models.