Research On Sheet Bending Rebound Control And Numerical Simulation Accuracy

In recent years, as the development of car industry gradually tends to bebody lightweight. High strength steel is widely used in automobile to improve itssafety and get the target of lightweight. In the forming process, the plasticdeformation of high strength steel plate is incomplete because of high yield limit,which leads to the springback of the parts after forming being outstanding. Atpresent, the springback of sheet metal is the most serious problem when the highstrength steel is being stampinged. Domestic and foreign researchers pay greatefforts to study the problem of springback. The Research methods including test,numerical simulation and theoretical analysis, etc. Now the numerical simulationtechnology can accurately predict both the fracture and wrinkling of the sheetmetal forming, but the prediction accuracy of springback is not satisfying.For the prediction accuracy of springback problem, this paper proposes twodifferent concepts----forming simulation accuracy and the numerical simulationaccuracy.We also propose two perspectives. One is improving forming simulationaccuracy by varying the process parameters,the other is improving the numericalsimulation accuracy by changing simulation parameters conditions. UsingDynaform software to simulated the U-shaped pieces can verify the feasibility. Inthis paper, we change the stamping speed and BHF and die clearance in thenumerical simulation of the process in order to analyze the impact of formingsimulation accuracy. By comparing forming simulation accuracy can be drawn:the stamping speed faster, the closer the simulation results; BHF greater, thecloser the simulation results; the die clearance smaller, the closer the simulationresults. Optimizing the above three parameters, we get the optimal experimentalconditions and then we can carry out practical experiments. On the basis of theoptimized process parameters, we change the number of integration points andthe unit network size. Change in the optimized process parameters on the basis of the number of integration points element mesh size of the two analog parameters,by comparing the numerical simulation accuracy can be drawn: the smaller theunit network, the simulation results closer to the experimental results, the greaterthe number of integration points The simulation results closer to the experimentalresults. By comparing the numerical simulation accuracy can be drawn: thesmaller the unit network, the simulation results closer to the experimental results,the more the number of integration points, the simulation results closer to theexperimental results.For the automobile beam-shaped part numerical simulation analysis, first,the process parameters which we got in the result of simulating the U-shapedpiece are used to simulate automobile beam-shaped part. Then, we analyzechanges in forming simulation accuracy. Finally, we verify the processparameters on the impact of the forming simulation accuracy and verify thereliability of the application of numerical simulation accuracy rule for simpleparts.