异形截面管不均匀膨胀充液成形数值模拟

目的对低碳钢不均匀膨胀率异形截面弯管零件充液成形工艺参数进行研究。方法利用有限元方法对低碳钢异形截面管零件的充液成形过程进行有限元仿真,对影响圆角破裂的关键工艺参数进行分析及优化。结果液室压力过小,弯管圆角内侧不易贴模;压力过大,圆角内侧会因材料过度减薄而发生破裂。推头轴向进给量合适时,可以在圆角处形成"有益皱纹",防止材料不均匀膨胀发生破裂。结论成形压力在300 MPa,推头的轴向进给量为50 mm时,可以成形出合格零件。

Numerical Simulation on Hydroforming of Irregular Cross-Section Tubes with Differential Expansion

The paper aims to study the hydroforming process parameters of fittings for low carbon steel irregular cross-section elbows with differential expansion. The hydroforming process of fittings for low carbon steel irregular cross-section tubes was simulated by the finite element method. Important process parameters which affected cracking of fillet were discussed and optimized. When the pressure in the hydraulic chamber was too small, the inner side of the elbow could not be pasted to the die. If it was too large, the inner side of the corner would crack owing to being over thin. If the axial feeding length of pusher was appropriate, some wrinkles would form in the round corner and could prevent the tube from cracking due to differential expansion. Qualified parts can be formed when the forming pressure is 300 MPa and the axial feeding length of pusher is 50 mm.