叶片高速切削的刀具-工件交互过程阻尼和非线性动力学研究

During the traditional research of stability prediction in metal cutting, the process damping is assumed as an additional viscous term whose value is inversely proportional to the velocity, and it leads to the conclusion that the process damping only exist in the low-speed cutting. However, such assumption cannot explain the large difference between the stability prediction and the experimental results in high-speed cutting, which will lead to the inefficiency of parameter selection, such that the performance advantage of machine tool is also constrained. To overcome the problem, around blade machining, this project aims to investigate the formation mechanism of process damping and nonlinear time-delay dynamics in high-speed cutting based on the cutter-workpiece interaction. By exploring the complicated relationships between technical parameters, surface morphology and structure modes, we try to discover the mechanisms of cutting force and process damping in high-speed cutting, establish the generalized predictable model of cutting force with multiple structure modes considered. We plan to propose the new calculation and stability prediction methods for nonlinear time-delay differential equation, in order to improve the prediction accuracy of stability in high-speed cutting. We try to propose the optimization method of technical parameters with stability and precision constraints for blade cutting, then the chatter suppression and material removal rate promotion and precision improvement can be achieved by cutting parameter adjustment or cutter modification.

在传统的金属切削参数稳定性研究中，过程阻尼被认为是低速切削过程的独有现象，在高速过程中通常被忽略掉。这种将过程阻尼简单考虑成反比于切削速度修正项的假设常常导致高速切削过程稳定性判别失准的问题，无法解释高速切削实验稳定边界远高于理论结果的现象，从而造成加工参数选择的盲目和保守，难以充分发挥机床的高速切削性能。针对该问题，本项目围绕叶片加工，开展高速切削过程阻尼机理和非线性动力学研究，探索刀具-工件交互作用下工艺参数、加工表面形貌和系统结构模态间的耦合关系，揭示高速切削力的内在形成机制和过程阻尼的产生机理；建立工艺系统结构多频耦合作用下的通用切削力可预测模型和动力学模型，提出非线性时滞动力学响应计算和稳定性分析方法，提升中、高速切削稳定域的判别精度；提出基于稳定性和精度约束的叶片工艺参数优化方法，实现叶片高速切削过程的振动抑制和材料去除率、成型表面精度的提升。

在传统的金属切削参数稳定性研究中，过程阻尼被认为是低速切削过程的独有现象，在高速过程中通常被忽略掉。这种将过程阻尼简单考虑成反比于切削速度修正项的假设常常导致高速切削过程稳定性判别失准的问题，无法解释高速切削实验稳定边界远高于理论结果的现象，从而造成加工参数选择的盲目和保守，难以充分发挥机床的高速切削性能。针对叶片等零件高速切削过程稳定性预测与实际相差较大的问题，从理论上研究了高阶模态对铣削工艺系统的稳定性的影响。在原有经典的的后刀面压入模型的基础上考虑了高阶模态对表面产生的影响，对Hertz提出的不规则表面的接触力模型进行了改进，使其更贴合铣削工艺系统的实际工况。并在在小幅值振动的假设下建立了一种基于Hertz理论的过程阻尼模型。该模型与切削参数，刀具几何参数，振动频率与幅值，工件材料的力学性能有关。避免了在辨识压入力系数Ksp时的昂贵且繁琐的实验和不准确的辨识过程。根据改进的模型，建立了带有周期系数的迟滞微分方程，采用了改进的数值积分法来预测系统的稳定域。针对现有铣削稳定性预测算法计算精度和效率低的问题，提出了一种高效高精的稳定性谱分析预测算法，该算法的计算精度和效率相对其它算法而已目前最优。且算法既能在恒定主轴转速铣削工况中进行分析，也能拓展到具有任意波形的时变主轴转速铣削工况中进行分析。开发了基于考虑过程阻尼的高速切削稳定性计算和参数优选软件模块，完成了典型叶片高速切削实验研究，并多次用于指导实际不同叶片（如大型空心风扇叶片等）生产过程中的切削提效。