镜像铣削加工奇异区域刀具路径优化

在大型薄壁件镜像铣削加工中，由奇异点引起的旋转轴运动不连续会影响加工质量，降低加工效率。针对此问题，分析了镜像铣削加工奇异点存在的原因，提出了一种奇异区域内的刀具路径优化方法。首先，针对镜像铣削系统的铣削头和支撑头分别建立了其旋转轴运动学变换模型，推导旋转轴微分运动关系，据此分析奇异点存在的原因及其对加工质量和效率的影响，定义了机床行程内的奇异区域范围。分析结果表明在镜像铣削系统行程范围内，仅铣削头存在奇异区域，而支撑头不存在奇异区域。然后，在镜像铣削加工刀路约束条件下，基于刀路光顺性指标建立了刀路优化模型。通过在加工曲面参数域内对跨越铣削头奇异区域的刀路进行调整，使得优化后的刀路更加光顺，以提高加工精度和表面质量，减少奇异区域附近的加工时间。最后，通过镜像铣削加工实验验证所提方法的有效性。

Toolpath optimization for mirror milling in singular area

In the mirror milling of large thin-walled parts, the discontinuous movement of the rotation axis caused by the singularity of the machine tools will reduce the milling quality and efficiency. To address this problem, this paper analyzes the cause of singularity in machining and proposes a toolpath optimization method in the singular area. First, the kinematics transformation model and the differential motion relationship of the rotation axis are derived for the milling head and support head of the mirror milling system. Based on this, the cause of the singularity and its influence on the machining quality and efficiency are analyzed, and the range of singular area is defined. Analysis shows that within the stroke of the mirror milling system, only the milling head has a singular area, but the support head does not. Then, the toolpath optimization model is established based on the toolpath smoothness index with the constraints of mirror milling. The toolpath passing through the singular area of milling head is optimized by adjusting the toolpath curve in parameter domain of machined surface to get smoother rotary axes movements, improve the machining quality and reduce machining time. Mirror milling experiment validates the effectiveness of the proposed method.