复杂型面拼接模具铣削过程动力学特性及加工误差反演研究

The processing error of complex surface joint mould is hard to be effectively controlled and the processing efficiency of it stays on a low level. All of these restrict the modification and the upgrading of high-end cars which made by our country. The reason is that the milling of the different hardness splicing zone always causes the load mutation. And this will cause significant shock and vibration for cutting tools and the accuracy of the mould surface will be reduced. Firstly, the project took the shock dynamics theory and the cutting method to research how the instantaneous impact force of splice zone impact on the size and position changes of tool-workpiece contact interface. It revealed the law of how the instantaneous impact force impacting on the material of main shear zone. And the study also established the undeformed chip thickness model of curve surface which be spliced. Thus revealed how the instantaneous impact force impact on spatial and temporal characteristics of chips before and after. On the other hand, the study got the critical condition of stable milling by established varying delays milling chatter stability region prediction model of the complex surface splicing mould. Then the mechanism of surface morphology influenced by the shock vibration and shock deformation of cutting tools are revealed which based on the surface morphology prediction model considering the dynamic response. And how the composite stiffness field of machine tool-tools-mould influenced the type surface accuracy was researched also. The above study is to achieve the inverse designs of milling conditions -shock deformation of tools, shock vibration and system integration stiffness-type surface precision. The study solved the crafts difficulties of the machining error control for splice transition zone of complex surface.

复杂型面拼接模具的加工误差不能有效控制、加工效率低下，制约着我国中高档轿车的改型换代，其原因是拼接过渡区的铣削加工易于引发载荷突变，对刀具造成冲击振动和冲击变形，从而破坏了模具型面精度。本项目首先采用冲击动力学和切削理论相结合的方法，研究拼接域内瞬时冲击力对刀具-工件切触界面大小和位置变化的影响，揭示瞬时冲击力对主剪切区工件材料失稳断裂的影响规律，建立曲面拼接域内未变形切屑厚度模型。进而揭示瞬时冲击力对切屑前后时空特征的影响规律，建立复杂型面拼接模具的变时滞铣削颤振稳定域预测模型，确定稳定铣削的临界条件。然后基于考虑冲击力动态响应的表面形貌预测模型，揭示刀具冲击振动和冲击变形耦合作用对表面形貌的影响机制，并研究机床-刀具-模具三者综合刚度场对型面精度的影响规律，以实现铣削条件-刀具冲击变形、冲击振动、系统综合刚度-型面精度的反演设计，解决复杂型面拼接过渡区的加工误差难以控制的工艺难点。

本项目针对复杂型面拼接模具的型面加工精度不能有效控制、加工效率低下的问题，通过模具铣削过程动力学行为的理论分析、数值仿真和铣削实验等开展研究。首先采用冲击动力学和切削理论相结合的方法，分析了拼接域内瞬时冲击力对刀具-工件切触界面大小和位置变化的影响，揭示了瞬时冲击力对主剪切区工件材料失稳断裂的影响规律，建立了曲面拼接域内未变形切屑厚度模型，得到了曲面模具拼接区域的瞬态铣削力特性。进而根据瞬时冲击力对切屑前后时空特征的影响规律，建立了复杂型面拼接模具的变时滞铣削颤振稳定域预测模型，确定了曲面模具稳定铣削的临界条件。然后基于考虑冲击力动态响应的表面形貌和加工误差预测模型，揭示了刀具冲击振动、曲面曲率因素等对表面形貌的影响机制，在分析铣削振动信号的非线性行为的基础上，提出了拼接区域表面形貌的非线性表征方法。最后研究了机床-刀具-模具三者综合刚度场对型面精度的影响规律，基于力椭球进行了刀具姿态选定和刀尖点变形误差分析，在大量的实验研究基础上，以表征模具表面质量的能量熵特征、刀具寿命以及去除率为目标函数，以铣削过程中的每齿进给量、主轴转速以及轴向切深为约束条件，基于改进的多目标遗传算法进行了反演设计，优化铣削工艺参数，为实现稳定高效的复杂型面拼接模具加工提供了系统的理论支持和实践依据。2018年5月部分技术转让给合作企业——哈尔滨新力光电技术有限公司，初步解决了复杂型面拼接过渡区加工误差难以控制的工艺难点。目前出版学术专著1部、发表SCI、EI检索论文6篇，投稿SCI、EI源论文4篇；授权发明专利3项，转让给企业发明专利1项；培养博士、硕士10人，企业技术人员10余名。