The Process Research On The Varying Curature Hot Bending Of High-stretch-steel Rectangular Tubes

Recently,the automobile industry has been focusing on the reduction in weight of car bodies to improve fuel economy and environmental protection.Using appropriate materials and late-model process to produce tubular bending parts,has great advantages for application in modern automotive lightweight.However,streamline design of car bodies makes most parts be varying curature structural parts,which gives a challenge to the manufacturing process of automotive structural parts.BR1500HS high-strength steel has high strength after quenching,and good forming qualities under high temperature.The varying curature hot bending technology can realize disposable forming and phasing of various curature tubular parts.So Applying the varying curature hot bending process to producing high-strength-steel tubular bending parts can satisfy the demands of lighter weight and higher safety for car bodies,which is of great significance for automobile lightweight manufacturing.Through analyzing the process of push bending in the varying curature hot bending of rectangular tubes,the mathematical relation between motion path of the roll and bending curve of the tube has been obtained.A motion path function applied to arbitrary curature bending has been established,and the simulation and experiments have proved the accuracy of the function.Moreover,based on the motion-path analysis of the varying curature hot bending and functional demands of every unit,the varying curature hot bending experimentn bal device for rectangular tubes has been designed.A simulation model for the induction hot bending of rectangular tubes has been developed.On one hand,the local induction heating of rectangular tubes has been simulated through ANSYS,then the temperature field has been acquired.On the other,the hot bending of rectangular tubes has been simulated through ABAQUS,and the influences of geometric parameters and process parameters on the forming qualities have been obtained for the fixed-curature and varying-curature hot bending.Experiments on the hot bending of rectangular tubes have been completed,and the influences of bending radius and pushing speed on cross-section deformation and wall thickness have been obtained,which consist with the simulation results.Further,the shape and size of the varying curature bending part coincide well with the simulation result.The hardness values of the surface meet the requirements,and the variation tendency of cross-section deformation and wall thickness is similar to the simulation values.The comparative analysis of experimental results and simulation results has verified the accuracy of the numerical simulation model.