Research On Hot Bending And Forming Technology Of High Strength Steel Dual Rectangle Cross-Section Tube

With the increasingly serious problems such as environmental pollution and shortage of resources,new energy vehicles have their unique advantages to rise and develop rapidly.Compared with traditional fuel vehicles,new energy vehicles mainly use electric energy,so a large number of battery packs placement and storage are particularly important.At present,the tube frame for installing battery packs is mainly produced by welding high strength steel tubes in turn.The production process is cumbersome and complex.Therefore,the tube bending and forming process is adopted to produce the battery frame and replace the original welding production process,which can significantly improve the overall performance and production efficiency of the battery frame.However,due to the introduction of round corners,the space utilization rate of the battery frame produced by tube bending and forming process is reduced compared with that produced by welding process,so it is necessary to study the forming technology of high strength steel dual rectangle cross-section tube,in order to reduce the bending radius of tube,improve the space utilization rate of new energy vehicles,and reduce energy consumption.The side push hot bending and forming process of the tube has been analyzed,and the theoretical calculation formula of bending radius has been derived.The force of tube in the process of bending has been analyzed,and the expression of the push force required to push the tube bending deformation has been obtained.The stress and strain of the tube in forming area have been analyzed,and the distribution law of shear flow has been solved.The analytical formula of critical axial compressive stress for wrinkling has been derived,and the influence laws of heating temperature and tube wall thickness on wrinkling have been analyzed.The finite element model of side push hot bending and forming process of the tube has been established,and stress state of the tube in forming area has been analyzed.The influence laws of the gap between the mandrel and tube,the extension distance of the mandrel,the pushing speed and the bending speed on the forming limit of hot bending of dual rectangle cross-section tube have been studied successively.The results show that the gap between the mandrel and tube,the extension distance of the mandrel and the pushing speed have important effects on the forming limit of the tube,and the bending speed has little effect on the forming limit of the tube.The reasonable value ranges of the main parameters have been determined under the condition that the bending radius of tube is 90 mm.The testing machine for hot bending and forming of high strength steel tube has been debugged and three typical bent samples of dual rectangle cross-section tube have been made.The test results have been compared with the simulation results and the accuracy of the simulation results have been verified.The precision and performance of the samples of dual rectangle cross-section tube have been tested,the results show that the samples have high dimensional accuracy and mechanical property up to standard,they can meet the requirements of use.