基于等效热-力载荷的20Cr_2Ni_4预应力车削残余应力模拟及实验

Simulation and Experimental Research on Residual Stress in Pre-Stress Turning of 20Cr_2Ni_4 Based on Equivalent Loading Theory

为快速准确预测20Cr2Ni4合金钢预应力车削表面残余应力的分布,基于等效热-力载荷建立三维有限元仿真模型,通过切削热-力模型确定等效热-力载荷的分布形状和强度,将切削过程等效为接触正应力、接触剪应力和热流通量在已加工表面的循环作用.模拟的残余应力分布趋势与测量结果基本吻合.基于上述模型研究了切削速度、进给量和预应力大小对残余应力分布的影响.结果表明,切削速度对残余应力分布影响不明显,减小进给量能使表面残余拉应力和最大残余压应力减弱,增加预应力能够有效地减小表面残余拉应力和增大最大残余压应力.

In order to predict the distribution of residual stress of 20Cr2Ni4 steel in pre-stress turning,a 3 Dfinite model was established based on equivalent loading theory to transfer the cutting process into a combined cycle effect of contact normal stress,tangential stress and heat flux.The shape and value of equivalent thermal-mechanical loadings were extracted from analytical model of cutting force and heat.The simulation results of residual stress distribution are basically consistent with the measured results.Analyzing and comparing the simulation results,the influences of cutting speed,feed rate and pre-stress on residual stresses distribution were studied.These results show that the effect of cutting speed on residual stresses distribution is not obvious.With the decrease of feed rate,surface residual tensile stress and the maximum compressive stress decrease accordingly. Moreover,the increase of pre-stress leads to the decrease of surface residual tensile stress and the increase of the maximum compressive stress.