关键词: 选区激光熔化, 拓扑关系, 偏置异常, 尖角特征

Abstract: Most of the existing offset algorithms were limited to simple graphics, which might not meet the complex structure requirements of real additive manufacturing parts. Therefore, a contour offset framework was proposed based on line segment topology. The types and formation mechanism of offset anomalies were studied, and the multi-loop processing algorithms such as line segment coincidence, (self) intersection, ring formation, ring reversal and ring failure were proposed to realize the processing of complex anomalies. The formation mechanism and influences of local sharp corners on the boundary were investigated, and the patching smoothing algorithm was proposed to optimize the angle of adjacent edges, almost eliminating the problems of singular sharp corners and void defects, and ensuring the stability of the algorithm. Using C++ language to write the algorithm program, compared with the results of the offset algorithm of the CGAL geometric graph library, the calculation speed of the contour offset method is faster, and the planned path is more in line with the machining geometric characteristics of the machining equipment. Compared with other scanning methods such as parallel line scanning and partition scanning, the total length of the present contour offset path is relatively lower and the overall scanning efficiency is higher.

Key words: selective laser melting, topological relation, offset anomaly, angular feature