复杂薄壁深窄V型长槽多轴精密加工振动与变形控制

Composite fan blade is the key to achieving structural innovation and technological breakthrough of high-bypass turbofans. To guarantee the service performance of composite fan blade, a leading edge protection (LEP), the structure of which is a deep and narrow V-shaped long groove with complex thin-wall, is needed to cover on its leading edge. The LEP can protect the composite fan blade from separation and desquamation, and improve the ability to resist bird strike and corrosion. The LEP is a typical part with complex structure and poor rigidity. On the one hand, the structure modal of machining system has strong time-varying characteristics, which makes machining vibration is difficult to control; on the other hand, the part deformation is sensitive to the distribution of residual stresses, which makes shape accuracy and surface quality of machined part is hard to guarantee. This project focuses on the main scientific issues in precision machining of the LEP of composite fan blade of aero-engines. These issues are dynamic modeling of strong time-varying system in machining the deep and narrow V-shaped long groove with complex thin-wall, the mapping modeling of residual stresses distribution and technological parameters, and collaborative optimization of tool rigidity and orientation under narrow design spaces. It is aimed at figuring out key technologies in multi-axis precision machining of deep and narrow V-shaped long groove with complex thin-wall, and verifying in the key model projects of large aero-engines in our country. The achievements of this project can enrich the existing theories in precision machining of complex thin-walled structures, and provide the related basic theories and key technologies for the urgently needed development of high-bypass turbofans.

复合材料风扇叶片是我国大涵道比涡扇发动机实现结构创新与技术跨越的关键。为保障复材叶片的使用性能，前缘必须采用复杂薄壁深窄V型长槽类零件—金属加强边结构，以防止复材叶片前缘分层开胶，并提高其抗鸟撞及抗腐蚀性能。金属加强边结构复杂、刚性极差，工艺系统结构模态的强时变特征造成多轴加工振动难以控制，同时零件的变形对残余应力的分布状态十分敏感，导致零件形状精度和表面质量难以保证。本项目面向航空发动机复合材料大型风扇叶片金属加强边多轴精密切削，研究复杂薄壁深窄V型长槽类零件强时变工艺系统动力学建模、切削残余应力分布与工艺参数的映射模型、小裕度条件下刀具刚度及刀轴控制协同优化等科学问题，解决复杂薄壁深窄V型长槽类零件的多轴精密切削关键技术，并在国家大型航空发动机重点型号工程中进行应用验证。研究成果可丰富复杂薄壁结构件精密制造理论，为我国急需的高性能大涵道比涡扇发动机的研制提供相关基础理论与关键技术支持。

项目针对大型复材风扇叶片钛合金前缘金属加强边材料去除量大、振动难抑制、变形难控制、刀位轨迹规划复杂等技术难题，研究了复杂薄壁结构铣削过程强时变工艺系统结构模态的演变规律和动力学模型，提出了基于刀轴矢量优化、结构刚度优化及切削参数优化的加工振动抑制方法，实现了加强边的稳定切削；研究了钛合金铣削残余应力的形成机理及梯度分布规律，提出了基于薄壳应力贴合的加工残余应力变形预测方法，实现基于非对称工艺设计的加强边定向/定量残余应力变形控制；研究了小裕度狭窄扭曲深腔特征约束下的刀具结构设计及刀具序列优化方法，提出了复杂通道锥度刀刀轴优化方法，完成了加强边内腔加工刀具刚性与刀轴平稳控制协同优化；突破了大扭度、超薄壁的深窄V型腔槽类加强边零件的精密数控加工关键技术瓶颈，完成了首台长江系列发动机钛合金前缘金属加强边装机件的试制，形成了钛合金前缘金属加强边国内唯一工程应用的制造方案，研制出CJ-1000和CJ-2000商用航空发动机多种构型的钛合金前缘金属加强边，实现了国产商用航空发动机该类零件的零突破，标志着我国已经掌握大型风扇叶片制造的核心技术。