大型超薄曲面镜像铣削的短时稳定性理论与主动抑振方法

Large and ultrathin surfaces are widely used in aerospace industries, such as aircraft skins and launch vehicle tanks. The accuracy of the wall thickness should be accurately controlled to balance the structural strength of the parts and the carrying capacity of the aircraft. Mirror milling, achieved by adding a follow-up support in the backside of the part, has become the latest manufacturing technology and development trend of large and ultrathin parts, since the wall thickness can be controlled by using close-loop method. Cutting vibration has become a major bottleneck that hinders the stable mirror milling of large and ultrathin parts. This project will study the key problem of vibration suppression in mirror milling system, and keep focus on transient stability prediction and sensitivity, optimal design of the support device and active vibration suppression. The mechanism of transient vibration in mirror milling of large and ultrathin surfaces will be discovered. The transient stability discrimination and sensitivity theory will be proposed to realize the optimal design of the follow-up support for stable machining. We will also develop the on-line identification of transient vibration and the active suppression method by varying parameter of the follow-up support. The newly designed supporting device, vibration real-time detection device and the active vibration suppression system will all be integrated into the mirror milling system to achieve the stable milling of the aircraft skins and launch vehicle tank bottoms with the wall thickness of less than 1mm. The wall thickness accuracy of ± 0.1mm for the large and ultrathin surfaces will be realized. These researches will provide theoretical and technical support to the manufacturing of the large and ultrathin aerospace surfaces.

大型超薄曲面零件广泛应用于飞机蒙皮和运载火箭贮箱等航空航天领域，需要控制壁厚精度以平衡零件的结构强度和飞行器的运载能力，镜像铣削通过在工件背面增加随动支撑实现壁厚闭环控制，成为该类零件的最新加工技术和发展趋势，本项目以大型超薄曲面零件镜像铣削为对象，围绕动态特性随时间和位置变化的工件在时变切削激励下振动抑制的关键问题，研究短时稳定性判别与灵敏度、镜像铣随动支撑装置优化设计和随动支撑变参数主动振动抑制，揭示大型超薄曲面零件镜像铣削振动的短时振动发生机理，建立切削振动短时稳定性判别和灵敏度理论，实现面向稳定加工的随动支撑优化设计，提出短时振动在线识别与随动支撑变参数主动抑制方法，开发镜像铣削的随动支撑与振动实时检测装置，以及随动支撑变参数主动抑振系统，实现壁厚小于1mm飞机蒙皮和火箭贮箱箱底零件的镜像铣削，壁厚精度达到±0.1mm，为航空航天大型超薄曲面零件控制壁厚的切削加工提供理论和技术支撑

大型超薄曲面零件广泛应用于飞机蒙皮和运载火箭贮箱等航空航天领域，其尺寸大、壁厚薄的特点导致自身刚性差，加工中易发生振动失稳和壁厚超差。镜像铣削通过在零件背面增加随动辅助支撑实时改善薄壁件加工区域的动态性能，是大型薄壁件壁厚减薄的最新加工技术和发展趋势。本项目研究内容包括大型薄壁件镜像铣削振动短时稳定性判别理论与稳定性图谱、短时稳定性边界对工艺系统参数的敏感度与随动支撑装置优化设计、短时振动在线识别与随动支撑变动力学参数主动抑制，以及镜像铣削加工短时振动分析与抑制系统的开发及验证。本项目提出了切削动力学中短时振动系统稳定性判别理论，揭示了短时振动的发生机理，并基于短时振动放大的最大幅值和最长持续时间构建了加工稳定性图谱；建立了短时振动稳定性边界对切削参数和支撑动力学参数的敏感度关系，提出了以最大短时稳定性边界为目标的支撑动力学参数优化设计方法，实现了随动支撑装置的优化设计；研究了短时振动在初始阶段的在线识别方法，提出了气动滚珠支撑下“工件-支撑”系统模态曲线中反共振区的形成原理，建立了随动支撑动力学参数对切削振动稳定性边界的影响关系，提出了支撑变动力学参数主动抑振方法；开发了集成短时振动稳定性判别、振动在线识别与随动支撑变动力学参数主动抑振的镜像铣削加工短时振动分析与抑制系统，在自主知识产权的镜像铣削设备上实现了运载火箭贮箱箱底的镜像铣削加工，最小加工壁厚1mm，壁厚精度达到±0.1mm，表面粗糙度Ra1.6μm，符合了质量要求，已通过飞行验证，推动了运载火箭整体箱底制造技术从“分片化铣+拼焊成形”到“整体成形+机械铣削”的升级换代；实现了C919中机身蒙皮的镜像铣削加工，解决了C919飞机铝锂合金蒙皮机械铣削的重大工程工艺攻关难题。项目共发表论文10篇，其中SCI期刊论文9篇，申请发明专利9项，已授权7项，基于项目成果实现了大型超薄曲面零件的镜像铣削加工，为我国大型超薄曲面零件的绿色、精确加工提供了新理论和新技术。