超高强度钢立铣工件温度分析及对加工表面质量的影响

以航空难加工材料300M钢为研究对象,基于立铣加工中的工件温度判断在铣削加工中是否出现了金相组织转变,进而分析不同工况下影响加工表面质量的因素。首先,将移动热源法应用于铣削加工中,计算考虑后刀面磨损的立铣加工工件温度,实验表明,计算值与实验值相比误差在10%以内。然后,分析了工件温度在时间上与空间上的分布,以及不同刀具磨损和加工参数条件下工件表面的温升规律,据此预测加工表面是否出现了组织转变,并结合金相组织观察进一步确认。最后,依据加工表面质量物理层面残余应力和显微硬度的检测数据,初步探讨了各因素对表面质量的影响。结果表明,在研究的加工参数范围内,并未达到金相组织转变温度,表面质量主要受铣削热力作用下的剪切面塑性凸出效应、后刀面挤光效应和热效应的影响。

Workpiece temperature analysis and its impact on machined surface quality of ultra-high strength steel in end milling

300M steel is chosen for the research object, which is the typical difficult-to-cut material in aviation industry. Microstructure changes are judged in milling based on the workpiece temperature. Then the main factors affecting the quality of the machined surface are also analyzed under different cutting conditions. Firstly, moving heat source method is applied to the milling process. The workpiece temperature model of end milling is established considering the flank rubbing effect. The temperature model is confirmed by the temperature measuring experiment and the error is less than 10%. Secondly, Temperature model is used to analyze the temperature variation on the workpiece surface over time, as well as the distribution along the depth into workpiece. The influences of processing parameters and tool wear on the surface temperature rise are studied. Finally, the quality of machined surface in physical level such as residual stress and microhardness is analyzed with different cutting conditions according to the test data. The results show that within the range of processing parameters studied, workpiece temperature is not higher than the phase transformation temperature. So, surface quality is mainly affected by the plastic bulge, flank squeezing and thermal effect caused by the milling force and temperature.