Research On Roll Forming And Pure Rolling Rotary Draw Bending Technologies Of Commercial Vehicle Bumper Beam

With the rapid development of the automobile industry,car ownership and penetration rate continue growing,and traffic accidents are also increasing.In recent years,the death rate of people caused by cars has decreased to a certain extent.Automobile traffic accidents have seriously threatened people's life and property health and become a safety problem that can't be ignored.Therefore,improving the collision performance of cars has become more and more important.At present,China has begun to try some mandatory collision safety rules,so that most commercial vehicles must pass the relevant collision laws and regulations before they can be sold on the market.In the field of commercial vehicles,the GB26511-2011 standard for commercial vehicles issued by the National Development and Reform Commission,which stipulates that he front and lower protective devices of commercial vehicles must meet the crash performance requirements.Therefore,it has become more and more important to improve the collision performance of automobiles.The "?"-shaped section bumper beam is made of high-strength steel,and its bending forming technology mainly includes two parts: first,roll bending forming and welding process are adopted to make "?"-shaped section of hot rolled beam and high strength steel strip.Second,using the designed bending forming device,the two sides of the profile are simultaneously bent to form a protective beam for the commercial vehicle.In the whole process,the roll bending unit is very complex,it is expected to be redesigned;In addition,defects appearing in the process of profile winding such as inner fold and outer fracture need to be solved urgently.The aim of this paper is to study the forming technology of cross beam,to optimize the design of "?"-shape section roll forming unit,and to carry out the simulation research on profile bending forming device,and to put forward a new bending scheme to reduce the defects such as wrinkles and fracture.The main research contents of this paper are as follows:1.Establishment of finite element model for roll forming and bending formingThe finite element simulation of roll forming and bending forming technology is carried out to analyze and solve the problems of mesh division,material parameters and boundary conditions involved in the modeling.2.Research on roll bending forming technology of "?"-shaped sectionBy using COPRA roll forming design software,the roll pattern of "?"-shaped section is obtained.The one-time roll forming method is designed to form the "?"-shaped section,and the "b"-shaped section is formed first,and then the "U"-shape is formed.The simulation modeling of "b"-shaped section is carried out to analyze the generation of edge wave of sheet metal,and the effects of flange height,sheet metal thickness,forming speed and other factors on the edge wave were studied.3.Numerical study on flexible core bendingThe simulation of flexible core bending forming device is carried out to verify the effectiveness of the simulation.The effects of the shape,number and tension of the pellets on the fold and section distortion were studied.4.Numerical simulation of rigid core bending formingA new method of bending rigid core is proposed to study the machining principle and make simulation analysis.The design of rigid die core and the influence of tension and pressure on winding defects were studied.