Study Of Thickness Optimization And Springback Of Continuous Variational Section Automotive Crossbeam

Lightweight body has gradually become one of the trends of development and a key research topic of automobile industry. Due to the continuous changing thickness distribution according to loads, tailor rolled blanks (TRB) have incomparable advantages compared with constant thickness blanks and tailor welded blanks (TWB). And have been one of the important ways of lightweight car.Despite the great advantages, tailor rolled blanks still have some problems to be resolved in practical production. Firstly, how to work out the thickness distribution according to the loads. It's a problem of thickness optimization. Secondly, since tailor rolled blanks have different thickness along the longitude; its springback quantity is also different after forming which greatly affects the assembly quality. How to minimize the springback quantity and how to balance it. It's a problem of springback control.The U-shaped part's bending springback principle of the blank under the blank hold force is analyzed theoretically. It mainly research the characteristic of the stress and strain during the forming and the springback principle of the blank. Blank hold force, One of the main factors of influence on springback, is analysised.There are large number beams in car body which suffer from heavy and complex loads. Those beams are especially suitable for producing with tailor rolled blanks. It can greatly reduce the weight of components and save materials and manufacturing cost.Aiming at the problem arising in current scientific research and production, this paper takes a typical car beam under the front seats for study, using the finite element software ANSYS and its parameter design language APDL, build a finite element model of beam through a program. The thickness distribution along the length of crossbeam is optimized according to its loads. The results showed that tailor rolled blanks has a good weight loss effect compared with constant thickness blank. The best thickness distribution crossbeam of auto is determined by comparing the weight loss effect and the actual manufacture conditions.The numerical simulations of forming and springback of tailor rolled blanks are carried out by using the finite element software ANSYS/LS-DAYNA. Results show that the thinning distribution of constant blank is more evenly, but for tailor rolled blanks, due to its thickness difference, the thinning ratios of its two ends are larger than its middle. The quantity of springback of tailor rolled blanks is between its corresponding thinnest and thickest constant blanks. It's proved that using different BHF in different position can balance the springback of the crossbeam and the overall springback quality is descended at the same time.A control method of different BHF in different time and position is adopted on the basis of the principle of forming and springback. In the previous stage of forming small BHF is applied, and the later stage the big BHF is applied. It can greatly decrease the overall springback quantity, and the distinction of difference position springback is very small. The best effect of springback control is achieved. In addition, the comparative analysis showed that too small or too big BHF of the later phase has adverse influence on springback control, and the springback quantity of crossbeam can be controlled to the minimum under the moderate BHF.