Research On The Balance Of Mixed Flow Assembly Line Considering Operator Workload

In recent years,the mixed-flow assembly line,as a high-efficiency and flexible production and assembly method,has been adopted by more and more manufacturing enterprises,especially discrete manufacturing enterprises such as automobiles and reducers characterized by multiple varieties and small batches.On mixed-flow assembly lines,the technological processes of different products are not exactly the same.In order to reduce personnel and equipment costs,similar tasks for different products are assembled on the same station.When the product variety increases sharply,the operator not only needs to master the assembly technology,but also needs to select the correct parts and assembly processes in the conversion of different assembly models,while bearing the physical and mental loads.The result of time balance alone results in uneven load between the workstations and bottleneck workstations,which greatly affects the overall performance of the system,and the occupational health and safety of employees cannot be guaranteed.Therefore,the operation is considered in the balance of the mixed assembly line.Load factors,and exploring the establishment of scientific and effective optimization models can help optimize the balance effect,and can also effectively reduce the operator's risk of occupational diseases such as cumulative musculoskeletal disorders.Aiming at the unbalanced workload of operators on mixed-flow assembly lines,the paper defines the workload as mental load and physical load,and establishes a brain load model that takes into account the complexity of assembly selection and the level of operator experience and considers the energy consumption of the operator.The physicalload model,which considers the two as a workload,as one of the objective functions,to ensure that workstations with high mental and physical loads are avoided;at the same time,for the sake of efficiency,the minimum beat will be taken.The equilibrium index with minimum idle time is also used as an optimization goal to ensure the optimization of time-related goals.In addition,considering the constraints of station,process order,and other general constraints of assembly line balance,a three-objective optimization model is comprehensively constructed..Considering the existing research to realize the conversion from multi-objective problem to single-objective problem by weighted sum averaging method,there are problems such as the magnitude difference between multiple targets and the weight setting is too subjective.Therefore,based on the characteristics of the mixed-flow assembly line,this paper selects the multi-objective genetic algorithm(NSGA-?)with the elite strategy as the basic algorithm,and uses codec methods,non-dominated set construction methods,solution space individual distribution uniformity control methods,and population evolution.The method is targeted to improve and the standard function is used for detection.The results show that the improved NSGA-? has better performance than the basic NSGA-?.Finally,the paper applies the model and solves the problem through an example.The research shows that the mixed-flow assembly line balance model constructed in this paper considering the operator's workload can effectively improve the balance of the assembly line.Comparing and analyzing the balance results before and after the operator load is considered and before and after the algorithm is improved,the analysis shows that the model and the algorithm are effective,and the model that considers the operator workload can help the company to further achieve load balancing under the premise of ensuring the time goal.The improved algorithm has better solution advantages.