Abstract: In order to solve the problem of inaccurate planning and coordination difficulties in the multi factory and multi workshop linkage production of automobile manufacturing enterprises,the problem was studied based on the leveling concept in lean production,considering the impact of inventory backlog or insufficient inventory in a limited capacity buffer zone on production stability. A dual level programming model for collaborative mixed flow production scheduling of multiple automobile factories was established.The upper layer establishes a cross factory transfer allocation model with the goal of minimizing the transfer volume between factories,while the lower layer establishes a workshop shift selection model with the goal of minimizing the reserve deviation in the buffer zone. A double layer genetic algorithm was designed to solve the model,and a minimum impact strategy was adopted to standardize the transportation volume and workshop output. The results of double layer optimization and single layer optimization were compared and analyzed through examples,and the scale of the examples was expanded.The simulation experiment results showed that the solution quality of double layer optimization was better,thus verifying the effectiveness and feasibility of the designed model and algorithm.

Key words: multiple automobile factories, collaborative mixed flow production scheduling, limited buffer zone, levelization, double layer genetic algorithm