Abstract: The part orientation of additive manufacturing (3D printing) has a great influence on some targets such as manufacturing cost,surface quality and printing stability.Three rotation angles around the coordinate axis of printing platform were used as the part orientation,and the multi-objective optimization model with the surface processing accuracy described by volume error and the manufacturing cost described by support material volume and part printing layer number was established.The orientation of two parts with different complexity based on Fuse Deposition Modeling (FDM) process was optimized respectively with the Multi-Objective Evolutionary Algorithm based on Decomposition (MOEA/D).Aiming at the problem that the part orientation in the optimized solution set was unstable,small quantity and discrete distribution,a stability coefficient based on the suspended volume of self-supporting surface was proposed to quantify the stability of the part orientation.Furthermore,combining with the continuity improvement of objective function,the multi-objective optimization model considering the stability of part orientation was reestablished and solved effectively.The optimized results showed that the continuity improvement of the objective function helped to obtain more solutions and the defined stability coefficient could effectively quantify the stability of part orientation.As a result,when the stability coefficient was less than the stability threshold value of 0.6,two parts′part orientations obtained by the optimization could meet the stability requirements of part orientation.

Key words: additive manufacture, part orientation, multi-objective optimization, stability coefficient, stability threshold

摘要： 增材制造(3D打印)零件的建造方向对制造成本、表面质量、建造稳定性等指标有着重要影响。以绕打印平台坐标轴旋转的3个角度描述建造方向,建立了以台阶效应引起的体积误差表征表面质量、以支撑材料体积和零件打印分层数描述制造成本的多目标优化模型,采用多目标进化算法(MOEA/D)分别实现了基于FDM工艺的两种不同复杂程度零件的建造方向优化。针对优化解集中的零件建造方向存在不稳定、数量偏少且分布离散问题,提出一种基于自支撑表面悬空体积的稳定系数指标来量化建造方向的稳定程度。结合对目标函数的连续性改进,重新建立了考虑建造方向稳定性的多目标优化模型并进行有效求解。优化结果表明,改进目标函数的连续性能获得更多优化解,定义的稳定系数指标能有效量化零件建造方向的稳定程度;当稳定系数小于稳定性阈值0.6时,两种零件优化获得的建造方向均能满足零件建造方向的稳定性要求。

关键词: 增材制造, 建造方向, 多目标优化, 稳定系数, 稳定性阈值