薄壁构件镜像加工刚度补偿支撑机构设计方法研究

Mirror milling machine is new equipment for the manufacturing of large thin-walled part, of which the machining and the supporting mechanisms are located on the sides of the part. Due to the variety of the part's geometric parameters, such as wall thickness and curvature, the consistence of precision in machining the parts with various wall thickness and curvature is still an unsolved problem for the existing mirror milling machine. The curvature changes with the machining region on the part, so the supporting mechanism is always located in the definite configuration to guarantee the normal supporting. Meanwhile, the distribution of stiffness of the supporting mechanism is also definite, but it is hard to achieve the approximate identical stiffness in the normal at different machining regions. The main problem in the design of supporting mechanisms of existing mirror milling machine lies in the contradiction of the requirements of geometric postures and identical stiffness in the normal. The main idea in the proposal is to introduce redundant actuation in the design of supporting mechanism, to achieve the stiffness compensation with little influence on the posture capability. The mapping between the characteristic parameters of redundant actuation and the variety of stiffness performance of the supporting mechanism is constructed, to reveal the compensation mechanism of redundant actuations on the stiffness. The matching regulation of supporting and machining mechanisms is put forward to formulate the design method of redundantly actuated mirror supporting mechanism. The achievements of the proposal will set up the theoretical basis and technical instruction for the design of mirror milling machines.

镜像加工装备是一种用于薄壁构件铣削制造的新装备，其中加工机构和支撑机构分别在被加工构件两侧"镜像"布置，在被加工构件不同曲率、壁厚处的加工精度一致性是镜像加工面临的问题。主要原因在于：支撑机构末端为满足沿被加工构件法向支撑，在构件不同曲率处机构位姿不同，沿被加工构件的法向刚度在各加工位置处无法做到近似恒等，造成加工变形的不一致。加工过程中运动位姿要求和等刚度支撑要求的矛盾是现有镜像支撑机构设计的主要问题。 本项目提出引入冗余驱动调整机构末端刚度的思路，以实现在不影响支撑机构位姿实现能力情况下的末端刚度补偿。建立冗余驱动支链特征参数与机构末端刚度变化的映射关系，揭示冗余驱动支链对机构末端刚度的补偿机理；提出镜像加工支撑机构与加工机构刚度匹配设计方法，形成面向末端刚度性能的冗余驱动镜像支撑机构设计方法。项目成果有望为镜像铣削装备支撑机构设计提供理论基础和方法指导。

镜像加工装备支撑机构设计面临的主要问题是加工过程中运动位姿要求和等刚度支撑要求的矛盾。本项目提出引入冗余驱动调整机构末端刚度的思路，以实现在不影响支撑机构位姿实现能力情况下的末端刚度补偿。本项目构建了支撑机构及各驱动支链的综合刚度映射模型，分析了冗余支链构型和驱动形式对机构末端刚度特征变化的影响规律；建立了镜像加工系统弹性动力学方程，分析了镜像铣削过程的力学行为特性，构建了冗余驱动支链参数与末端刚度性能的关联模型；构建了镜像加工装备冗余驱动支撑机构实验系统，开展了镜像加工轨迹实验。.在理论研究方面，提出了面向刚度性能的冗余驱动支链优化设计方法，为镜像支撑刚度补偿机构设计提供理论基础；提出了基于最佳近似的刚度综合方法，为基于冗余驱动的刚度补偿支撑机构设计提供依据。在应用方面，设计了用于镜像加工实验系统，开发了控制系统及运动规划方案，实现了空间曲面的镜像加工轨迹。在本课题执行期内，以第一作者和通讯作者发表/录用受本课题资助的论文6篇，其中SCI源期刊3篇；申请发明专利4项，其中授权2项，公开2项。结合本课题研究，协助指导博士研究生1名、硕士研究生3名（已毕业1名）。