| Energy conservation, consumption reduction of power, environmental protection and security are required as the development of new generation cars. With the advantage of excellent intension and temper, high stretch rate and processing hardening rate and light weight, high-strength hot-rolled steel plates are widely used in car chassis and subassemblies. So it is necessary for various forming properties of high-strength hot-rolled steel plates to be studied further.Besides, there are lots of flanging characters in auto-body panels. Usually, auto-body panels are flanged after drawing and edge-trimming. Thus, study of key simulation technologies of high-strength hot-rolled steel plate, analysis of flangablility of high-strength hot-rolled steel plate and cracking and wrinkling sensitiveness of mould parameters and procedure parameters are needed. It’s very important for high-strength hot-rolled steel plate to be used and promoted.This thesis focused on the design of a model which would be used to evaluate the flangeability of high-strength hot-rolled steel plate by simulation and optimization and the key technologies of flanging forming simulation. Then it brought out the evaluated index, summarized the influence of mould parameters, procedure parameters and material parameters. At last, the evaluated mould was developed and carried out validated experiments.By plenty of simulation, a“Wâ€-shape model was brought out. The contour line of the die was assembled by two arcs with radius 30mm and central angle 900, an arc with radius 45mm and central angle 900 and two lines with 25mm long which were tangent with the three arcs. The width of blank was fixed by the horizontal projection of the three arcs and the two lines. The contour line of punch was got by offsetting from that of die.The key simulation technologies were summarized in detail by applicability analysis of seven flow stress model and Barlat 1989, Barlat six-parameter yield criterion and Hill 1948 yield criterion. By analyzing the thinning distribution, the flanging process parameters and die parameters were optimized. The critical flanging height was brought out to evaluate the flangeability of high-strength hot-rolled steel, which the height was called when the edge of blank appeared cracking and micro-wrinkling after the operation of flanging.The critical flanging height sensitiveness was studied minutely by adjusting stretch-flanging radius, shrink-flanging radius, chamfering of die, punch and binder, clearance between die and punch, blank holder force and virtual speed.At last, a set of mould was developed to evaluate the flangeability of high-strength hot-rolled steel plate, and the validated experiments were carried out. |
