H13淬硬模具钢精车过程的数值模拟

Numerical Simulation of Fine Turning for H13 Hardened Die Steel

采用热力学耦合有限元方法研究了淬硬钢精车过程中切屑形成规律。运用H13 淬硬模具钢流动应力模型进行数值模拟,考查了H13淬硬模具钢精车过程中工艺参数对工件性能和刀具的影响。结果表明:切削速度愈高,进给量愈小,刀具刀尖半径愈大,则工件加工层上的静水拉应力愈小,表面质量愈好; 淬硬钢精车时径向力起主要作用,大于切削力;切削速度愈大,切削力和径向力则愈小,愈有助于改善工件加工层上的表面质量;切削速度、进给量和刀具刀尖圆角半径愈大,工件和刀具温度愈高,愈易导致刀具前刀面扩散磨损和刀具后刀面磨损。研究结论有助于优化H13淬硬模具钢精车过程中工艺参数选择和改进刀具镶片设计。

A coupled thermo-mechanical model of plane-strain orthogonal turning of hardened steel was presented. The flow stress of the work-material was taken with the previous model proposed by authors in order to take into account the effects of the large strain, strain-rate, temperature and initial workpiece hardness. Then a series of numerical simulations had been done to investigate the effects of machining parameters on the machinability of hardened steel AISI H13 in fine turning processes. Higher speed, smaller feed and larger tool tip radius help to decrease hydrostatic tension in machined layers, which improves the surface integrity of the machined workpiece and eliminate residual stresses. The thrust force is dominant and larger than the cutting force in fine hard machining. As cutting speeds increase, cutting and thrust forces decrease, which helps to improve the surface integrity of the machined workpiece. As cutting speed, feed and tool tip radius increase, the workpiece and tool temperatures increase, which may induce more serious diffusion crake and flank wears in the tool. The obtained results are helpful for optimizing process parameters and improving the design of cutting inserts in fine turning of hardened steel AISI H13.