Research On Multi-part Layout Optimization Technology For Additive Manufacturing

In recent years,the emergence of additive manufacturing technology has played a significant role in promoting the development of the manufacturing industry.Additive manufacturing technology uses discrete layered processing of three-dimensional models,and uses layered overlay manufacturing on processing platforms to produce parts.Compared with traditional manufacturing processes,additive manufacturing does not require mold design,and has a high degree of freedom in design.The manufacturing process is simpler and faster.It can not only process parts with complex geometric shapes,but also perform concurrent manufacturing of different parts.With the continuous improvement and development of additive manufacturing technology,the application of additive manufacturing is becoming more and more widespread,and it has been applied in aerospace,medical,automotive and other fields.Therefore,additive manufacturing technology has also become a research focus.This paper mainly focuses on the optimization of forming direction and multi part layout in additive manufacturing.The specific contents are as follows.(1)During additive manufacturing,the forming direction of a part can have a certain impact on the surface quality and forming time of the part.For the surface quality of parts,this paper gives priority to the surface quality of functional features,proposes an adaptive surface roughness(weighted calculation of the surface roughness of each feature)as the evaluation standard for surface quality,and establishes an adaptive surface roughness mathematical model.For forming time parts,the factors affecting forming time are analyzed in detail,and a mathematical model of forming time is established.Genetic algorithm is used to solve the single objective optimization of the forming time and surface quality objective functions.Experimental results show that the proposed objective function can converge and is feasible.(2)A multi-objective optimization problem for surface quality and forming time is proposed.Aiming at multi-objective optimization in the forming direction,multi-objective problems are analyzed,and multi-objective optimization algorithms are studied.Considering the two factors of part surface quality and forming time,the NSGA-Ⅱ algorithm is used to solve multi-objective optimization of the forming direction to obtain a set of Parteo solutions for the forming direction.The appropriate forming direction can be selected from the Pareto solution set according to requirements.At the same time,the algorithm in this paper and Pandey’s algorithm are compared and analyzed.The results show that when the minimum forming time is guaranteed,the forming directions obtained by the two algorithms are not significantly different.In order to ensure the minimum surface quality,the minimum adaptive roughness of this algorithm is 10.26 μm,and the minimum average roughness of Pandey algorithm is 12.75μm.This algorithm reduces the roughness by 19.52%.Under the premise of ensuring the surface quality of functional features,the algorithm in this paper can obtain better forming directions.(3)Aiming at the problem of multi part layout in additive manufacturing,the forming efficiency and layout method of multi parts were studied.Firstly,the proposed multi-objective optimization algorithm is used for optimization calculation.In order to ensure the quality of the part,the direction with the smallest adaptive roughness is selected as the forming direction of the part;Then,the projected contour from the part to the printing platform is solved,and the multi-part layout optimization problem in additive manufacturing is transformed into a twodimensional part layout optimization problem.A two-dimensional part positioning algorithm based on trajectory line NFP is proposed and combined with genetic algorithm to search for the global optimal solution of two-dimensional part layout;Finally,using C++programming to achieve algorithmic programming,the optimization results of parts layout are obtained,and compared with optimization methods using envelope rectangles and genetic algorithms.The experimental results show that the multi part layout method based on NFP and genetic algorithm proposed in this paper can effectively improve the space utilization of the printing platform.