Research On The Nesting Algorithm Of Two-dimensional Irregular Parts Under Process Constraints

The problem of nesting is to place a series of parts or graphs on a given plate without overlapping,and to ensure that it will not exceed the plate boundary.Nesting problem is widely existed in industrial manufacturing,and in different industries,some materials are subject to the actual conditions such as material and cutting equipment during processing.In the actual layout,these process constraints should be taken into account.If we ignore the actual processing demand of industrial production,it will lead to the poor applicability of process and the poor operability of process in nesting design,and often needs to be revised again.The purpose of the study of two-dimensional irregular parts nesting considering process constraints is to make the nesting algorithm applicable to the actual industrial processing,reduce the distance of machining path,save the time of nesting and increase the material utilization rate.Aiming at the nesting of the actual sheet metal industry,the paper focuses on three aspects:the process constraints solving strategy,the irregular parts positioning strategy and the sequencing optimization strategy.The main research contents are summarized as follows:(1)A Process Constraints-based Two-dimensional Nesting Algorithm(PCTNA)was proposed.According to the processing method of irregular parts and plates in the sheet metal industry,the process constraints involved in the actual nesting are studied.Combined with the shortcomings of the existing literature research,the process constraints considered in the sheet metal nesting are the process gap between irregular parts and the parts with holes,including the processing gaps of the part with holes.Using the proposed solution strategy,in order to meet the actual industrial production demand and improve the cutting efficiency,a certain process gap is added into the parts and plates at the beginning of the nesting.When the parts with holes,combined with the proposed irregular part positioning strategy,the appropriate parts are placed in the holes to reduce the waste of the plate.(2)Based on the idea of the no-fit polygon,the No-Fit and Inner-Fit Polygon(NIFP)irregular part positioning strategy considering process constraints was proposed.Calculate the legal placement of the parts to be placed in the sheet,and deals with the process constraints of the irregular plates,grooves and the parts with holes.While considering the process constraints,screening and judging the placement points between the blank space and the gaps between parts during the nesting process,and selecting the appropriate parts to fill,which will improve the utilization ratio of the plates.At the same time,combined with the proposed Genetic Algorithm and Tabu Search(GA-TS)sequencing optimization strategy,the parts are arranged in order,and optimize the nesting results continuously,so as to obtain the optimal solution of the sheet metal industrial nesting under process constraints.The experimental results show that the solution strategy proposed in this paper can reduce the cutting time and path of the nesting and improve the cutting efficiency;By comparing and analyzing experimental data of two commercial softwares,and evaluating the nesting of irregular plates,it can be concluded that the nesting strategy proposed in this paper can deal with the nesting problem,can fill the gap between parts and nesting the irregular plates.