Research Of Irregular Sheet Metal Parts Nesting Algorithm

The layout of sheet metal parts is widely applied to industry manufacture of Aero-Space and machinofacture, and the result of layout will influence every norm directly such as the rationality and economical efficiency of the parts manufacture. Because most of the sheet metal parts are irregular and the large blanks are existent in the inside of them, the research of compatible layout algorithm is the important task in the layout research.In the matter of the complexity of mathematical calculation, the problem of irregular parts layout belongs to an NP-complete problem theoretically in itself. Because of the complexity of parts’shape itself and calculation, the resolution of this problem is very difficulty. Along with the development of computer aided nesting technology, people are able to use the artificial intelligence to implement the regular parts layout, but owing to the irregularity of sheet metal parts mostly, the computer aided nesting is still not very satisfied. Therefore, starting from the irregularity shape of sheet metal parts, the study of this paper propose a layout algorithm fitted to irregular parts based on the experience of ancestors’ research in this field. The main research works are as follows:(1) Analyze the mathematical model of sheet metal parts layout and propose the part pretreatment. By means of the convenient computer description of sheet metal parts, we could reduce the layout process time on the premise of describing parts’ characteristic completely. The part pretreatment mainly include the classification of concavo convex parts, the parts recombinant or not and concretely recombinant methods, the acquiring of minimum envelop rectangle and so on.(2) Comparing the research of layout banking regulation in the layout method of minimum envelop rectangle, analyze the deficiency of them and propose the improved lowest horizontal search algorithm starting from the parts irregularity. In addition, the study of this paper regards genetic algorithm as the regulation of layout order and integrate the Genetic Algorithm with improved lowest horizontal search algorithm to a mixed algorithm by contrasting the several common algorithms of artificial intelligence algorithm, which will solve the problem of low partial utilization in the envelop rectangle of irregular part.(3) The soft used to verify the algorithm of this study is auto-layout system of sheet metal part which is developed by ObjectARX of secondary development tool based on AutoCAD. This system possess well maneuverability, drafting some irregular sheet metal parts and nesting these parts by the algorithm researched. Analyzing the result of layout, we could discover that the algorithm is highly active and have high usage. In addition, aiming at the existence of large blank space between parts in the diagram that is formed by minimum envelop rectangle, this paper further improve the utilization by manual intervention and reach the expected effect.This algorithm in this paper has a good suitability in the layout of irregular sheet metal parts. The larger the internal blank of part is and the bigger the difference between parts is, the more obvious the superiority of algorithm is. The research to prove that the algorithm is critical to reducing raw material waste, improve economic efficiency of enterprises has important theoretical significance and practical significance.