基于质量流量优化的超临界CO_(2)辅助切削加工热平衡研究

Thermal Equilibrium Research of Supercritical CO_(2)Assisted Cutting Process Based on Mass Flow Optimization

低温切削技术良好的制冷效果使其在难切削材料加工中逐渐得到应用,而在不同切削参数下基于低温流体参数进行切削区与射流场热平衡调控的研究甚少。针对超临界CO_(2)辅助切削加工热平衡调控问题,将切削区及射流场视为一个热力学系统,从连续时域的角度分析了系统的物质和能量的输入输出,即超临界CO_(2)的焓变和切屑的能量变化。进而基于CO_(2)热物性、金属切削原理和热力学理论,提出了变切削速度情况下,基于射流质量流量的切削区及射流场热平衡调控方法。通过不同质量流量下的相关实验,验证了基于质量流量热平衡调控方法的可行性。实验结果表明该热平衡调控方法能够加快切削区及射流场的热平衡过程,且不同切削速度下的切削区温度、主切削力、表面粗糙度至少分别降低了7.8%、7.9%、7.1%。

Cryogenic cutting technology with good cooling effect has been gradually applied in the machining of difficult-to-machine materials,but little research has been done on the thermal equilibrium regulation of the cutting zone and the jet field based on cryogenic fluid parameters under different cutting parameters.Aiming at the thermal equilibrium regulation of supercritical CO_(2)-assisted cutting processing,the cutting zone and the jet field are considered as a thermodynamic system,and the material and energy input and output of the system,i.e.,the enthalpy change of supercritical CO_(2)and the energy change of the chip,are analyzed from a continuous time-domain perspective.Further,based on the CO_(2)thermal properties,metal cutting principles and thermodynamic theory,a thermal equilibrium regulation method of cutting zone and jet field based on the jet mass flow rate is proposed for the case of variable cutting speed.The feasibility of the thermal equilibrium regulation method based on mass flow rate was verified by relevant experiments under different mass flow rates.The results show that the thermal equilibrium regulation method can accelerate the thermal equilibrium process in the cutting zone and the jet field and the cutting zone temperature,main cutting force,and surface roughness are reduced by at least 7.8%,7.9%,and 7.1%,respectively,at different cutting speeds.