Research On The Key Technology Of Rotary Draw Bending Forming Of Commercial Vehicle Protective Beam

With the development of the economy,commercial vehicles are the hub of goods transshipment across the country and an important part of the logistics industry.Their role is extremely critical.However,due to their high quality,more pollutant emissions,and large inertia when driving,accidents may be caused.The injury will be more serious,so it is particularly important for commercial vehicles to carry out reasonable lightweight design and improve the collision safety performance.Based on this background,the commercial vehicle protective beam with "日"-shaped section made of high-strength steel has been developed to meet the above two requirements.Highstrength steel profiles with " 日 "-shaped section can maximize the anti-collision performance and energy absorption characteristics of high-strength steel.The rotary draw bending forming technology can be used to bend both ends of profile at low cost and efficiently,making it an excellent protective beam for commercial vehicles.However,high-strength steel has poor plasticity and low thickening anisotropy index,and the "日"-shaped section is very complicated.it will produce cross-sectional deformation,external cracking,internal thickening and wrinkling defects after rotary draw bending,which greatly impairs its anti-collision performance.Therefore,this paper studies the key technology of rotary draw bending forming of commercial vehicle protective beams,aims to suppress bending defects,forms commercial vehicle protective beams with excellent product quality,and provides technical guidance for the production of protective beams.The research details and completions are as follows:⑴ The novel rotary draw bending device is introduced,its working principle is described,and the rationality to effectively reduce the risk of external cracking of the part is analyzed theoretically.Based on the principle of the process and the idea of finite element modeling,the finite element model is established.⑵ The defined method can effectively study the deformation of the section and the thickening of the inner side of part after rotary draw bending.Investigate the influence of the bending radius,the number of core,and the gap between the core and the profile on the cross-sectional deformation and inner thickening defects.The results show that increasing bending radius can reduce the degree of bending deformation,and increasing the number of cores can expand the support range of the core to the cavity,thereby effectively reducing defects,and the maximum deformation section position of the profile is related to the number of cores.The larger the gap between the core and the inner side of the profile,the smaller the rate of section width change and the greater the thickening rate,while the height change rate and the offset of the support beam first decrease and then increase.⑶ Orthogonal test analysis is used to clarify the primary and secondary relationship of the influence of process parameters on defects,and obtain a better protective beam forming scheme.The results show the factor that has the greatest influence on the width change rate,the thickening rate and the offset of the support beam is the bending radius,and the element that has the important impact on the height change rate is the number of core.The optimal combination is: the radius is 640 mm,the gap is 0.6mm,and the number of core is related to the bending radius,which can be obtained by the formula in this article.⑷ Aiming at the wrinkling defects: integrate other solutions of defects,and rationally and innovatively design the novel flexible core.Its application improves the accuracy of the bending section of the part,and effectively reduces the deformation of the section,the thickness of the inner side and the wrinkling defects.Based on the above research,the protective beam with better forming quality is finally produced.⑸ The collision performance test of the commercial vehicle protection beam that is reasonably developed and produced has been carried out.The results show that the anti-collision performance and product quality of the commercial vehicle protection beam are excellent and meet the requirements of national standards.This proves the rationality of the overall research and development ideas for commercial vehicle protective beams in this article.