Research On Modeling And Algorithm Of Parallel U-shaped Assembly Line Balancing Problem Based On Forward And Backward Priority Values

The development of the manufacturing industry is promoted by the continuous innovation of production methods.Before the industrial revolution,small workshop-style production methods could only support people to engage in simple hand-made activities;after the industrial revolution,manpower was gradually replaced by machines,workers were concentrated in factories for production,and the era of machine manufacturing came;after the20 th century,primary mechanical production methods could no longer meet the increasing demand for commodities,and mass manufacturing emerged in response to the times.Assembly line production is an important method of large-scale manufacturing,which originated in the automotive industry and gradually developed into all walks of life.With its high efficiency and low unit product cost,the assembly line satisfies the demand for small varieties and large quantities of products,and the balance of the assembly line had subsequently become an important technology that has attracted much attention.Straight-line assembly lines first appeared,and on this basis,U-shaped assembly lines,parallel assembly lines and other assembly lines appeared.Assembly lines with different layouts have different characteristics and correspond to different assembly line balancing techniques.Because of the existence of the crossover workstations,the U-shaped assembly line is more flexible,and the length of the assembly line is also shortened,which is convenient for system optimization and is suitable for just-in-time production;However,due to the uniqueness of its layout divided into the entrance side and the exit side,U-shaped assembly line balancing problem is also more complicated.Parallel assembly lines allow for the simultaneous production of multiple products with different cycle times,which further improves the flexibility of the assembly line.At the same time,it is also necessary to consider the issue of common cycle time in the assembly line system.Parallel U-shaped assembly lines combine the advantages of the U-shaped assembly line and the parallel assembly lines,which are flexible and can produce multiple products at the same time.The related papers of U-shaped assembly line balancing problem,parallel assembly lines balancing problem and parallel U-shaped assembly lines balancing problem are all studied in this article,and algorithms and cases of them are studied;the basic concepts of assembly line balancing problem and the theory of directed graphs have been sorted out;the process of improving the priority relationships diagram of the assembly line balancing problem based on the characteristics of the U-shaped assembly line is explained,and the method of constructing the assembly line partition with the help of the characteristics of parallel lines is illustrated;Following the workstation types and z-q partition distribution rules in the parallel U-shaped assembly line,a mathematical model of type-I parallel U-shaped assembly line balancing problem is established;the heuristic algorithm based on forward and backward priority values and partition allocation rules is designed;calculation experiments based on classic cases of assembly line balancing problem are performed,32 cases of U-shaped assembly line balancing problem are calculated by heuristic algorithm and genetic algorithm separately,and the results show that the heuristic algorithm runs more stable and faster;56 cases of parallel U-shaped assembly line balancing problem and the corresponding combination cases of U-shaped assembly line balancing problem are calculated respectively by heuristic algorithm.The results show that parallel U-shaped assembly lines balancing method is better.