Research On Balencing And Scheduling Methods Of Mixed-Model Assembly Line Oriented To Order Production Mode

The order oriented production model can reduce the risk of material shortage or backlog caused by demand forecast deviations,enabling enterprises to gain higher profits.The mixedmodel assembly line can realize the order oriented production mode and meet the rapid changes and diversified demands of the market.How to improve the load balance of workstations and the rationality of production scheduling schemes,ensure balanced performance of assembly lines and timely delivery of orders,has become an important research topic in the production of different types of products with similar production processes on mixed-model assembly lines.The balance and sequencing of assembly lines are the core elements of line research that strongly influence the company’s production process.Therefore,in this thesis,the balance and scheduling optimization of mixed-model assembly lines are studied.The main research content is as follows:A research framework for balance and scheduling optimization of mixed-model assembly line based on order production mode was proposed.Based on the analysis and research of the theory of balance and scheduling optimization for order oriented mixed-model assembly lines,a research framework for balance and scheduling optimization has been determined.The basic idea is to prioritize customer orders on the mixed-model assembly line as the production scheduling attribute,prioritize the workstation allocation scheme optimized by balancing the mixed-model assembly line as the production scheduling premise,and achieve the optimal mixed-model assembly line production scheduling scheme as the goal,thus solving the problems of low delivery rate of mixed-model assembly line orders on schedule,imbalanced workstation load,and difficult decision-making of order scheduling schemes.A customer order priority ranking method based on comprehensive indicator weights is proposed.Order priority,as an important attribute of production scheduling optimization,establishes a reasonable priority evaluation index system from three dimensions:financial dimension,product dimension,and customer dimension by following the principle of indicator evaluation,and evaluates order priority based on the order priority evaluation index system.When processing customer orders,the attribute hierarchy and entropy method are used to calculate the subjective weight and objective weight of the order priority rating index,and the combination weight of the order priority rating index is obtained according to game theory.Finally,the priority ranking results of orders are calculated by using the distance between good and bad solutions.The rationality of the proposed method was verified by taking the order priority evaluation of a mixed-model assembly line for automotive engine cylinder heads of a certain enterprise as an example.A hybrid assembly line balance optimization model considering load balancing between workstations was constructed.Based on the analysis of the comprehensive priority relationship of job tasks,a mathematical model for load balancing in the workplace has been developed to optimize the hybrid model assembly line,with the minimum production cycle serving as a research object.The optimized genetic algorithm would solve the optimization model,and the task coding strategy is designed to make the individuals generated during the implementation of the algorithm always meet the priority constraint.By searching within the feasible solution range with a high fitness value,the optimal solution of the problem can be found effectively and quickly,and it can achieve the best solution for assigning assembly workstations.Apply the method proposed here to optimize the balance of line for automotive engine cylinder heads,and the balance rate of the assembly line has been significantly improved,verifying the effectiveness of the proposed method.A mixed-model assembly line scheduling optimization simulation model based on Plant Simulation has been constructed.Aiming at the scheduling of the assembly lines,based on obtaining order priority and assembly line balance optimization results,the minimum production cycle unit is optimized for production scheduling,and a dual objective production scheduling model is established to minimize completion time and the total time for product switching settings.By establishing a mixed-model assembly line model for automotive engine cylinder heads in Plant Simulation software and conducting scheduling optimization simulation experiments using genetic algorithm tools in the software,the scheduling plan for the mixed-model assembly line was obtained,which proved the availability of the means and models proposed in this thesis.