钢管短芯棒拉拔过程应力场的数值模拟

Numerical Simulation of Stress-field for Steel Tube Drawing Process with a Short Mandril

通过对一个典型的带芯棒拉拔过程的模拟,分析了在拉拔过程中芯模应力和钢管应力的分布特点。芯模的最大应力出现在芯模的浅表层,在周向表面上呈点状分布,而芯模其他部位承受的应力并不是很大。在拉拔过程中,芯模最大应力从芯模的定径带和前倒角交界处附近转移到芯模定径带靠近芯模锥面附近。芯模的这种应力分布状况和芯模的失效形式密切相关,芯模应力在周向呈点状分布使得芯模局部容易产生粘着磨损,芯模的定径带附近承受交变的最大应力使得芯模容易产生微裂纹,微裂纹的扩展使得芯模开裂。钢管周向和径向的应力值不大,而轴向应力值较大,最大轴向应力出现在钢管与芯模的接触部位。

A typical steel tube drawing process with a short mandril was simulated, and the stress-field of mandril and steel tube were analyzed. The maximum stress occurs on the surface of the mandril and small stress occurs on the other part of the mandril. The location of maximum stress transfers from the boundary of working land and shoulder fillet to the boundary of working land and mandril chamfer during drawing process. Because the mandril failure is related to the stress conditions, adherent wear occurs on the local surface of the mandril. Due to the punctate stress, the microcracks form on the surface and propagate to induce the mandril fracture. The axial stress on the steel tube which appears on the contact region of the steel tube and mandril is larger than the radial and circumferential stress.