钛合金TC4切削过程流动应力模型研究

运用有限元技术对切削过程进行仿真可以预测切削力、切削温度、应力分布,优化刀具参数和切削条件。建立适合于切削条件中大应变、高应变率条件下材料的流动应力模型,是切削过程有限元仿真的关键技术。文章通过正交切削实验和有限元迭代的方法,修正了难加工材料TC4在大应变、高应变率条件下的J-C流动应力模型,使修正模型能够适应切削仿真中的大应变、高应变率要求。计算结果表明,采用新的J-C流动应力模型进行计算,所得主切削力值与实验测量值的平均误差从36.28%降为12.06%,进给力的平均误差由原来的61.03%降为现在的25.57%。该修正的流动应力模型比用霍普金森实验所得到的流动应力模型更适合于切削过程的有限元仿真,可以提高切削仿真的计算精度。

Research on the flow stress model of titanium alloy TC4 during the cutting process

Finite element analysis based techniques are available to simulate cutting process and offer several advantages including prediction of cutting forces,distribution of stresses and cutting temperatures,optimization of cutting tool geometry and cutting conditions.The determination of the model of material flow stress at high strain rates and strains suitable for the cutting process is a key technique for the FEA simulation of machining operations.In the presented paper,the flow stress model of titanium alloy Ti 6Al 4V was modified using orthogonal cutting experiment and machining simulation in order to make it fit the cutting process better.The result of simulation indicated that the average prediction error of the cutting forces decreased from 36.28% to 12.06%,and the average prediction error of the thrust forces decreased form 61.03% to 25.57 when using new flow stress model in the machining simulation process.The flow stress model obtained by orthogonal cutting experiment and machining simulation was proved to be more suitable for the FEM simulation of machining operations than that determined by the Hopkinson's bar high-speed compression tests,and it could improve the accuracy of the FEM simulation of cutting process.