基于教与学优化的LPBF零件构建方向优化算法

Optimization algorithm of building orientation in LPBF based on teaching-learning-based optimization

在激光粉末床熔融(LPBF)工艺下,零件打印方向的选择是分层建造工艺规划的关键步骤,打印方向选择的好坏会直接影响零件的成型质量和打印成本。零件的打印方向通常由操作员手工选择,打印前无法确定最佳建造方向。针对LPBF零件定向问题,从打印成本角度出发,提出一种基于教与学优化(TLBO)的金属3D打印零件方向优化算法。首先根据金属3D打印工艺流程建立LPBF工艺综合成本模型,该模型考虑了零件支撑结构体积、打印高度、打印时间,然后通过变换STL模型几何表示,建立打印方向与成本的多目标优化模型,采用TLBO进行全局搜索,得到零件最佳建造方向,解决了金属3D打印工艺成本高的问题,实现了成型方向的自动选择。最后在实例模型中介绍了该方法的使用,并通过与商业软件Magics中生成打印方向以及遗传算法(GA)优化方向对比,证明了所提方法的有效性和运行效率。

In laser powder bed fusion(LPBF)process,the choice of printing direction is the key step of the layered construction pro-cess planning.The choice of printing direction will directly affect the forming quality and printing cost of the part.The printing di-rection of the part is usually manually selected by the operator,and the optimal construction direction cannot be determined before printing.Aiming at the problem of LPBF part orientation,a teaching-learning based algorithm(TLBO)based orientation optimiza-tion method for metal 3D printing parts was proposed from the perspective of printing cost.Firstly,according to the metal 3D print-ing process,a comprehensive cost model of LPBF process was established,which considered the volume of supporting structure,printing height and printing time of parts.Then,a multi-objective optimization model of printing direction and cost was established by transforming the geometric representation of STL model,and the optimal construction direction of parts was obtained by using TLBO for global search.The high cost of metal 3D printing process is solved and the automatic selection of forming direction is re-alized.Finally,the application of the proposed method is introduced in an example model,and the effectiveness and efficiency of the proposed method are proved by comparing with the generated print direction in commercial software Magics and the optimization direction of genetic algorithm(GA).