Research On Mixed-Flow Scheduling In Maintenance Production System For EMU Bogies

With the development of high-speed rail transit technology,the quantity of electric multiple units(EMUs)increases sharply and the trains speed up constantly.The requirement of train performance and reliability is higher and higher.Bogie,as an important part of trains,its maintenance production is confronted with the problems of large quantity and short delivery time.In this paper,a company's EMUs bogie maintenance workshop is taken as the research object.Aiming at solving the problem of high maintenance production demand and lack of ability of delivery on time,the methods of value stream map and modeling simulation are used.First,according to theoretical analysis and modeling simulation method,the maintenance production of bogie is studied and optimized.On the basis of software Plant-Simulation,model the maintenance production line.In the current production state,from the first car entering to the last one exiting,the simulation results show that the total processing time is 118 days,16 hours and 55 minutes,and the production balance rate is 12.22%.Through bottleneck analyzer,it's found that bogie decomposition,bogie protection,small and medium parts maintenance are blocking processes.The value stream map of lean production was used to analyze the wheel set maintenance line.And it is concluded that there was insufficient production capacity in the wheel unloading process and gear box running-in.Then,using the goal of the shortest maintenance work time and maximum production rate,and with the model change access path as constraint conditions,the mixed flow production scheduling scheme was provided based on the genetic algorithm optimization.It is concluded that contains while only considering the maintenance work time,the total maintenance work time was 117 days,19 hours and 07 minutes,reducing 21 hours and 48 minutes,and the production balance rate was 10.78%.While only considering production balance rate scheduling scheme,the total maintenance time was 118 days,1 hour and 39 minutes,which reduced 15 hours and 16 minutes,and the production line balance rate was 12.56%,which increased 0.34%.The blocking process was not improved.While considering production balance rate and the maintenance work time same time,the total processing time of bogie maintenance production is 117 days,20 hours and 20 minutes,which reduces 20 hours and 1 minute,and the production balance rate is 10.8%,which increases 0.02%.At last,for wheel unloading,increase the number of stations to optimize;for gear box running-in,process decomposition is adopted to increase the process ability;set the buffer for the blocking processes.After optimization,the total production time is reduced by 37h,the balance rate is increased by 17.5%;the blocking ratios of the bogie decomposition,bogie protection and small and medium parts maintenance are reduced by 15.57%,15.73%and 40.85%respectively.This paper analyzes the EMUs bogie maintenance production line with the modeling and value stream map.And put forward the improvement plans.The achievements provide the technical support for mixed flow production and optimization of complex maintenance production system with multi-process and multi-products.