| In the context of the current sluggish market economy and Industry 4.0,manufacturing enterprises are facing more intense internal and external market competition.And S company of a machine tool mixed assembly line in this context,the internal problems become more prominent,respectively in the product accumulation,high staff costs and staff workload imbalance.Because the improvement results of traditional mixed-model assembly line balancing methods usually have a certain gap with the optimal solution.Therefore,aiming at this problem,this paper studies the balance optimization of machine tool mixed flow assembly line by means of multi-objective optimization.In this paper,a machine tool mixed-flow assembly line of S company is taken as the research object,and three different methods are used to carry out the research : initial balancing of assembly line,algorithm optimization and real-time simulation.Firstly,based on the field investigation of the mixed-model assembly line of machine tools,the information of assembly time,assembly process and assembly cost of employees is sorted out.On this basis,the initial balance of the mixed-model assembly line of machine tools is carried out by using the method of assembly task redistribution of assembly line,and the scheme after initial balance is taken as an initial solution of the subsequent optimization process.Secondly,the optimization evaluation index is improved according to the actual needs of the enterprise,and the minimum beat,minimum employee cost and minimum workload balance are taken as the optimization objectives to establish a mathematical model.Then according to the characteristics of multi-objective mathematical model,the improved NSGA-Ⅲ algorithm is used to solve the problem after verifying the effectiveness of the algorithm.After that,the Pareto frontier is screened by the improved TOPSIS method based on game theory.On the basis of avoiding the problem that the traditional TPOSIS method is too subjective in determining the weight,the optimal solutions under two different conditions of cost demand and beat demand are obtained respectively,and the results before and after the initial balance are analyzed and compared.Finally,according to the characteristics of the fixed mixed flow assembly line,the simulation model of the mixed flow assembly line of the machine tool is established by using Plant Simulation software,and the influencing factors of the waiting time in the actual production process are added.Through the analysis of the simulation results,the effectiveness of the optimal scheme under the beat demand is determined.Aiming at the problem of mixed flow assembly line balancing of machine tools,this paper uses the improved NSGA-Ⅲ algorithm to solve the Pareto frontier composed of 94non-dominated solutions.After screening and verification,the final scheme is compared with the minimum beat before improvement.It is reduced by 85.5 min,the assembly line balance rate is increased by 17.29 %,and the smoothness index is reduced by 97.37,which makes the mixed flow assembly line of machine tools reach the overall optimization and solves the actual production problem of S company. |
