Research On Key Technology Of Roll Forming For Ribbed Rectangular Profile

With the implementation of the new development concept,people’s demand for energy saving and environmental protection is growing,the automotive manufacturing industry follows the trend and focuses on the development of lightweight,high-strength steel and aluminum alloy materials are widely used.Among them,high-strength steel can achieve lightweight and enhance the safety performance of the car at the same time and the proportion of application in the whole vehicle manufacturing process is increasing.As an important passive safety device,the protective beam is one of the key components of the vehicle,and the use of high-strength steel in the manufacture of the protective beam can make it have good comprehensive performance.The protective beam studied in this paper is mainly used for the front lower protection of commercial vehicles,which needs to be manufactured by roll forming process to produce ribbed rectangular profile first,and then the final product is made by bending forming device.The roll forming process is complicated,and there will be edge wave defects and rebound behavior in the forming process,which affects the final product quality.Since the theoretical study of roll forming is not yet perfect,trial-and-error method is usually used for production debugging in actual manufacturing,which needs to consume a lot of resources.The use of finite element simulation to simulate and analyze the roll forming process can efficiently obtain the forming law,and the results can play a guiding role in the manufacture of products,which is of practical significance.In this paper,with reference to the actual production experience,the roll hole design of the protective beam is completed with the help of relevant software.And the finite element model of ribbed rectangular profile roll forming is constructed in ABAQUS software to numerically simulate the forming process of the protective beam,and the simulation results are analyzed to summarize the profile forming law and provide guidance for the production of the protective beam with ribbed rectangular cross-section.1.The finite element model of roll forming for ribbed rectangular profile was established,and the parameters of forming pass,bending angle,billet width and roll diameter were determined according to the proposed new idea of forming,with reference to the industry guidelines and actual production experience,to complete the design of the protective beam with ribbed rectangular cross-section.The design of the roll hole shape of the product was completed.At the same time,we optimize the design with the help of COPRA software,build the roll model by CATIA software,and finally establish the finite element model of ribbed rectangular profile roll forming in ABAQUS software,and simulate the forming process.2.The roll forming process of the "b" section profile is analyzed,based on the simulation results of the first stage of the roll forming of the guard beam,i.e.the "b" section profile,the stress-strain situation of the sheet during the deformation between the rolls is investigated,and the three different stages of feeding into the rolls,forming between the rolls and leaving the rolls are discussed.The three different stages of feeding into the rolls,forming between the rolls and leaving the rolls are discussed.The results show that the deformation of the sheet between the rolls is mainly concentrated in the bending angle range,but a small amount of plastic strain is generated at the edge due to excessive longitudinal stress,and there is an edge wave defect.By discussing the effect of different process parameters on the edge wave,it is known that the intensity of the edge wave defect increases with the increase of friction coefficient,increases with the increase of roll gap,and decreases with the increase of roll pitch,in which the roll pitch has the greatest effect on the edge wave.3.The roll forming process of the ribbed rectangular profile was analyzed,and the Bauschinger effect and Young’s modulus changes during the forming process were investigated based on the simulation results of the final protective beam forming.By comparing the simulation results under three different hardening laws,it was found that the hybrid hardening model considering the Bauschinger effect was the closest to the actual situation.The Young’s modulus of B700 L high-strength steel was found to decrease nonlinearly with the increase of pre-strain through cyclic loading tests,and the value stabilized after decaying by 18.5%.Based on the test results,a rebound model considering the variable Young’s modulus was constructed to further investigate the rebound process of roll forming.Through the discussion of the geometric parameters and process parameters of the profile,the rebound law was summarized as follows: the rebound angle increases with the increase of bending radius,roll gap,roll spacing and other parameters,and decreases with the increase of sheet thickness,while the friction coefficient has little effect on it.