Research On Parts Selective Assembly And Assembly Scheduling Of Complex Products Based On Assembly Constraint BOM

In discrete high-end equipment manufacturing,such as large ships,space shuttles,high-end CNC machine tools,industrial robots,rail transit equipment,etc.,all belong to complex product manufacturing.Complex products represent the technical commanding heights of equipment manufacturing industry,which is an important way to promote the intelligent transformation and upgrading of China's equipment manufacturing industry,an important pillar of national defense,industrial industry and national economy,and an important guarantee to enhance national comprehensive national strength and international competitiveness.The assembly of complex products is closely related to the reliability and stability of products and is an important quality control link.Moreover,the fixed-point and manual assembly operation mode is the main mode of complex products,which leads to a relatively long period of assembly in the whole manufacturing process,which is an important link affecting assembly efficiency.Therefore,there are two major factors that directly affect the assembly quality and efficiency in the assembly process of complex products.First of all,the matching accuracy between assembled parts directly affects the final quality of complex products,and there are some differences in the actual machining dimensions of a batch of parts.However,due to the size tolerance zone of parts,even if the size of a single part is within the tolerance zone,the matching relationship between parts may still fail to meet the desired requirements of assembly accuracy,which can only be reworked and reloaded by assembly workers many times,resulting in the decline of assembly quality and the loss of efficiency;Secondly,at present,the assembly of complex products is generally checked before assembly.However,if the assembly is started after the materials in all processes are fully assembled,the assembly efficiency will be greatly lost.Therefore,it is of great significance to study the assembly problem of complex products,solve the problem of parts optimization and matching caused by the difference of processing sizes of batch parts,and solve the problem of parallel optimization and scheduling of assembly under non-uniform conditions,so as to improve the assembly quality and efficiency of complex products.Focusing on the above problems,based on assembly constraint BOM,this paper studies the parts selective assembly and assembly job shop scheduling from two aspects of improving assembly quality and efficiency.The main research contents are as follows:Firstly,aiming at the assembly of complex products,a concept of assembly constraint BOM is proposed,and a structure of assembly constraint BOM is designed and established.On the basis of traditional BOM structure,information such as dimension chain constraint matching relationship,assembly process,assembly process time,etc.among cooperating parts are brought into assembly constraint BOM for management,and workshop assembly process based on assembly constraint BOM is expounded.Therefore,it lays a theoretical foundation for the optimal matching of assembly parts and the optimal scheduling of assembly tasks.Secondly,on the basis of assembly constraint BOM,considering multi-dimension chain constraint matching factors,aiming at the phenomenon of batch parts size difference in the assembly process of complex products,a mathematical model of parts optimization and matching with the goal of Satisfaction rate of assembly performance and assembly accuracy is established,which is used to solve the problem of parts optimization and matching in batch parts,thus achieving better size matching between parts.Around this model,a hybrid genetic simulated annealing hybrid(GASA)algorithm is designed to solve it.In order to produce a feasible matching scheme,a two-dimensional tour coding method is adopted and crossover and mutation operators are improved.At the same time,a simulated annealing algorithm is introduced to avoid the algorithm falling into local optimum.Thirdly,the characteristics of fixed-point assembly and assembly job shop scheduling problem are analyzed.On the basis of assembly constraint BOM,the mathematical model of complex product assembly scheduling is established with the minimum maximum completion time as the optimization goal,thus solving the parallel problem of assembly parts arrival and assembly process under the premise of non-uniformity,which will greatly shorten the assembly cycle of complex products.According to the above model,an improved hybrid variable neighborhood discrete differential evolution(IDDE-VNS)algorithm is designed to solve it.The coding method based on process relation matrix is adopted,so that the algorithm can search in the discrete feasible region,and the mutation and crossover methods are improved accordingly to improve the global search ability of the algorithm.At the same time,in order to enhance the local search ability of the algorithm,the optimal individuals in each iteration of the algorithm are searched in variable neighborhood.Finally,taking the assembly of marine diesel engine turbocharger of Chongqing J Shipping Company as an example,the experimental simulation verifies that the proposed assembly parts matching method and assembly job shop scheduling method can effectively improve the product assembly quality and efficiency,and have guiding significance for actual workshop assembly.