基于AC转角变化最小的五轴FDM熔覆路径的法矢量优化技术

五轴熔覆通过AC转台带动工件转动，使得喷嘴轴线尽可能与熔覆曲面的法矢量重合以达到最优的熔覆效果。熔覆指令通过AC转角离线计算的曲面法矢量来调整喷嘴轴线的位置。由于熔覆曲面数据噪声和外形特征的影响，熔覆路径上两个邻近点AC转角的差异可能非常大，从而使得控制系统自动插补得到的两点间路径与两点连线段的差异很大，导致熔覆过程中工件损坏或者熔覆质量降低。为了克服这一缺陷，基于遗传算法提出一种AC转角的优化方法，使得邻近点AC转角的差异尽可能小。在此基础上，进一步对差异较大的点的五个指令变量(X, Y, Z, A, C)进行线性插值，从而达到熔覆路径优化的效果。算法被集成到了自主研发的五轴FDM三维打印系统，并采用多个复杂曲面的熔覆实例验证其有效性。

Normal Vector Optimization Technology of Five-axis FDM Cladding Path Based on Minimum AC Rotation Angle Change

Five-axis cladding is achieved by rotating the workpiece on an AC turntable so that the nozzle axis coincides as closely as possible with the normal vector of the surface to be clad. The nozzle axes are positioned by offline calculation of the surface normal vector based on AC rotation angle. The difference between the AC angles of two neighbouring points on the cladding path can be large due to noise and shape characteristics of the surface, which makes the path between two points automatically interpolated by the control system very different from the line connecting two points, resulting in workpiece damage or cladding quality reduction. To overcome this shortcoming, this paper proposes an optimization method of AC rotation angle based on a genetic algorithm, so that the difference of AC rotation angle between adjacent points is as small as possible. Based on this, the five command variables (X, Y, Z, A, C) of the points with large differences are further linearly interpolated to achieve path optimisation. The algorithm has been integrated into a self-developed five-axis FDM 3D printing system, and its effectiveness has been verified by several cladding examples of complex surfaces.