弱刚性薄壁件双转台五轴联动加工稳定性研究

Weak stiffness thin-walled components are widely used in aerospace industry. These components are typical thin-walled key parts with complex structure, thin wall, weak stiffness and high surface accuracy requirements. As the most important manufacturing method in aerospace industry, multi-axis NC cutting is prone to produce non-linear and time-varying problems associated with material removal. The mechanical and thermal loads on parts usually induce the evolution of the microstructure and structure of materials. This phenomenon will affect subsequent processing. In the actual production process, it is common that the performance of machine tools can not be fully developed due to the conservative selection of processing parameters. The improper selection of processing parameters often leads to instability and chatter in the cutting process. This phenomenon is extremely prone to cause processing defects and even faults of processing equipment. How to realize the high-efficiency and steady-state cutting of this kind of parts has always been a difficult problem to be solved urgently. Therefore, for the thin-walled parts with weak stiffness, the precise evaluation of the process system performance in the manufacturing process and studying on cutting stability under the influence of dynamic characteristics of machining system are of great significance solve the problems of long processing cycle, difficult control of processing deformation and quality of this kind of parts. They will help to achieve high quality and high efficiency cutting.

在航空航天工业中，弱刚度薄壁件有着广泛的应用，该类零部件属于典型的薄壁关键零件具有结构复杂、壁薄、刚度弱、表面精度要求高等特点。多轴数控切削加工作为航空航天工业中最主要制造手段，其过程中易产生伴随材料切除的非线性、强时变问题。零件承受的力热载荷，通常会诱发材料微观组织和结构的演变，从而影响后续加工。在实际生产过程中，由于加工参数选择过于保守而导致机床性能难以得到充分发挥的实例屡见不鲜，加工参数选择不当，常常导致切削过程失稳，发生颤振等现象，易引发加工缺陷甚至是加工设备故障的产生，如何实现被该类零件的高效、稳态切削一直以来都是亟需解决的难题。针对弱刚度薄壁件的加工制造过程的工艺系统性能的精准评价，探究加工系统动态特性影响下的切削稳定性问题对解决该类零件加工周期长、加工易变形和加工质量难以控制的问题，最终实现高质量、高效率切削加工有着极重要的意义。

在航空航天工业中，弱刚度薄壁件具有结构复杂、壁薄、刚度弱、表面精度要求高等特点。多轴数控切削加工作为航空航天工业中最主要制造手段，其过程中易产生伴随材料切除的非线性、强时变问题。如何实现被该类零件的高效、稳态切削一直以来都是亟需解决的难题。本项目首先针对薄壁类零件加工系统的双转台五轴机床多轴联动加工空间动力学特性进行研究，对双转台五轴机床加工空间性能谱标定，研究该加工系统动态特性变化规律；其次对双转台五轴机床加工系统综合频响特性进行研究，建立刀具子系统与工件子系统动力学模型，结合有限元仿真和实验，提出考虑模态交叉效应综合频响函数预测方法；最后对加工系统动态特性影响下的弱刚性薄壁件多轴加工稳定性进行研究，建立动载荷作用下弱刚性薄壁件动态切削厚度模型及时滞预测模型与瞬态切削力预测模型；提出加工空间内任意加工位置、任意刀具位姿状态下的加工系统稳定性谱模型，基于交叉模态参数的不对称性分析，揭示模态耦合效应的对加工稳定性的影响。构建基于数字孪生技术的叶轮叶片加工参数优化模型，并通过叶轮叶片加工实验进行验证。结果表明，运用本项目所提出的工艺优化方法后，实现了叶片的稳态加工，同时叶片加工轮廓度平均误差降低了18.75%。本项目研究成果对实现薄壁类零件高质量、高效率切削加工，有着重要的意义。