基于损伤力学的高速切削锯齿形切屑及动态切削力预测研究

Serrated chip is a significant characteristic of the high speed cutting different with traditional cutting, which has important influence on the cutting force, cutting temperature, tool wear and the quality of machined surface. According to the adiabatic shear serrated chip produced in high speed cutting and the periodic cutting force caused by it , the prediction of chip morphology and dynamic cutting force based on damage mechanics is carried out in this project. Through the dynamic mechanical properties experiments, orthogonal cutting experiments and finite simulation reverse, a constitutive relationship is built, which taking account of the effect of damage and fitting the cutting process. The model of adiabatic shear in high speed cutting which considers the damage is built through introducing the damage diffusion equation. The perturbation analysis is carried out to obtain the characteristics scale and width of adiabatic shear band. The models of serrated chip and deformation conditions in the primary shear zone are built, combining with the characteristics scale of adiabatic shear, a prediction model of serrated chip expressed by material properties and cutting parameters is put forward. The model of stress distribution and time-varying equation are built, combing with the calculation of strain, strain rate and temperature in the adiabatic shear band, a prediction model of dynamic cutting force is presented. The prediction of serrated chip and dynamic cutting force of some typical materials in high-speed cutting is conducted to validate the prediction results. This study is of great contribute to improve the high speed cutting theory and guide a reasonable choice of cutting parameters.

锯齿形切屑是高速切削有别于传统切削的显著特征，对切削力、切削温度、刀具磨损及表面质量都有重要影响。针对高速切削过程中的绝热剪切锯齿形切屑及其引起的周期性切削力，基于损伤力学，开展切屑形态及动态切削力的预测研究。结合动态力学性能实验、正交切削实验和有限元反求，建立适合切削过程并考虑损伤的材料动态塑性本构关系；通过引入损伤扩散方程建立考虑损伤的高速切削绝热剪切模型，采用扰动分析获得绝热剪切的特征尺度和宽度；提出锯齿形切屑模型和第一变形区变形条件计算模型，结合绝热剪切带特征尺度，建立以材料特性和切削参数表达的锯齿形切屑预测模型；建立产生绝热剪切锯齿形切屑时应力分布模型及时变方程，结合绝热剪切带内应变、应变率和温度的计算，提出动态切削力预测模型；进行典型材料高速切削绝热剪切锯齿形切屑和动态切削力的预测及实验验证。研究结果对于揭示高速切削加工机理、指导加工参数的合理选择具有重要的理论意义及应用价值。

锯齿形切屑是高速切削有别于传统切削的显著特征，对切削力、切削温度、刀具磨损及表面质量都有重要影响。项目针对高速切削过程中的绝热剪切锯齿形切屑及其引起的周期性切削力开展建模及预测研究，主要完成内容如下：(1)开展材料力学性能实验；进行正交切削实验获得切削力和摩擦条件；完成切屑形成过程的有限元建模；建立计及损伤的本构关系和损伤演化方程；构建适合切削过程并计及损伤的材料动态塑性本构关系。(2)建立考虑损伤的高速切削绝热剪切模型；进行扰动分析，得到绝热剪切的特征时间尺度和长度尺度；建立绝热剪切带宽度模型；分析材料特性和变形条件对绝热剪切演化的影响规律。(3)建立高速切削锯齿形切屑模型；推导锯齿形切屑的齿距、锯齿频率和锯齿化程度的表达式；提出第一变形区应变、应变率和温度的计算方法；构建以材料特性和切削参数表达的锯齿形切屑预测模型；分析切削参数对锯齿形切屑形态的影响规律。(4)建立基于应力的动态切削力模型；提出绝热剪切带内应变、应变率和温度的计算方法；构建以材料特性和切削参数表达的动态切削力预测模型；分析材料特性和切削参数对动态切削力的影响规律；进行典型材料高速切削锯齿形切屑及动态切削力的预测及实验验证。主要研究成果和创新点为：(1)提出了基于损伤力学的高速切削绝热剪切建模及分析方法，不仅有助于推进高速切削加工机理的研究，也可为其它动力学冲击条件下绝热剪切的研究提供借鉴。(2)建立了由材料特性和切削参数表达的高速切削锯齿形切屑预测模型，解决高速切削锯齿形切屑的定量预测问题。(3)建立了由材料特性和切削参数表达的高速切削动态切削力预测模型，解决高速切削动态切削力的理论预测问题。(4)提出了适合切削过程并计及损伤的材料动态塑性本构关系建立方法，为更有效的高速切削绝热剪切分析及更准确的高速切削有限元模拟奠定基础。