基于纳米压痕技术的刀具涂层本构关系精确测量方法研究

Coated cutting tool is one of the important parts for modern machining technology，the mechanical quality of the tool coating directly affects the working durability and machining efficiency for the coated cutting tool. There is no effective method to evaluate the mechanical property of the cutting tool coating so far, thus active design for tool coating and coated tool selection in machining are seriously limited. This project curries out some investigations on accurately measuring the constitutive relation of the cutting tool coating using nanoindentation technology, based on the previous researches for comprehensive mechanical property evaluation of coating and nanoindentation testing technology. The project propose that helpful imprint mappings are taken account and strategies for reducing parameter coupling are studied for improving the identified accuracies of constitutive relation. The deformation theory and material fluid law for imprint will studied utilizing the plastic deformation and large deformation theories, imprint morphology characteristics for different tool coating are obtained; Simultaneous, in order to improve the accuracy of the result calculated by inverse analysis, some methodologies e.g. nonlinear feedback, Lyapunov function are considered for eliminating or reducing the parameter coupling. The strategies for accurately measuring the constitutive relation of the coating will obtained via the above investigations and a viable method will be also found for evaluating the mechanical property of cutting tool coating. This research will provide some theoretical guidance for actively design and usage in practical machining for coated cutting tool.

涂层刀具是现代加工技术不可缺少的重要部分，涂层性能的好坏直接影响刀具的寿命和加工效率。目前还没有有效的办法获得刀具涂层的综合机械性能，严重制约着刀具涂层的主动设计及涂层刀具的选用。本项目在已探明的涂层机械性能评估及纳米压痕检测的基础上，研究利用纳米压痕技术精确测量刀具涂层本构关系问题。以精确测量刀具涂层本构关系为目标，提出采用有效压痕形貌特征及弱化本构关系中材料参数耦合性的方法，提高本构关系的测量精度；探索基于塑性成形和大变形理论的压痕成形机理及压痕形貌变化规律，获得有效表征不同刀具涂层材料力学性能的压痕形貌特征；探索通过非线性反馈、李雅普诺夫函数等方法弱化材料参数的耦性性，解决材料参数的强耦合性影响反向求解精度的问题，获得刀具涂层本构关系的精确测量方法，为刀具涂层综合机械性能的获得提供可行性方案，为刀具涂层的主动设计及其工程应用提供理论依据及技术指导。

涂层刀具是现代加工技术中不可缺少的重要工具，涂层性能的好坏直接影响刀具的寿命和加工效率。以往对刀具涂层机械性能的评价主要依赖于其硬度、弹性模量、涂层与刀具基体的附着力的测量，而更能体现刀具加工性能和寿命的刀具涂层屈服强度、极限强度及强度—变形关系等性能却鲜有学者研究。本项目在已探明的涂层机械性能评估及纳米压痕检测方法的基础上，研究利用纳米压痕技术精确测量刀具涂层本构关系问题。为刀具涂层更多机械性的获得能提供可行的新方法，为刀具涂层的主动设计、实际生产中涂层刀具的合理选用提供理论指导。项目按计划完成了纳米压痕技术反向测量刀具涂层本构关系过程的数值模型；以精确测量刀具涂层本构关系为目标，提出了同时采用载荷-位移曲线和有效压痕形貌提高本构关系的测量精度，针对不同的涂层材料，分析了不同材料、不同压头形状、不同载荷历程等工况下压痕形貌的成形规律及变化特征，完成了刀具涂层有效压痕特征信息的识别和提取；为进一步提高刀具涂层本构关系的测量精度，采用对优化算法改进和弱化本构关系中材料参数耦合性的措施，提高了反向分析的效率和精度，到达了刀具涂层本构关系精确测量的目的。本项目的研究成果为刀具涂层综合机械性能的获得提供可行性方案，为刀具涂层的主动设计及其工程应用提供理论依据及技术指导，具有一定科学意义和工程应用价值。