Research On The Just-in-time Materials Distribution And Scheduling Of Multi-vehicle In Automobile Mixed Flow Assembly Line

Along with the rapid development of modern manufacturing technology,the frequency of product renewal iteration is getting higher.Mixed-flow assembly lines suitable for assembling different types of products in multiple batches and small batches have been widely used in the automobile industry.In the fierce market competition environment,enterprises focus on how to ensure parts supply to production lines efficiently.More and more car manufacturers use material supermarkets as intermediate storage areas,which stores materials from central warehouses temporarily.What’s more,AGV,tractor and other tools are used to provide just-in-time parts supply for its mixed flow assembly line flexiblely and reliablely.However,it is a great challenge for material distribution that the inventory capacity is limited and the assembly line must not be out of stock.Material distribution based on material supermarkets mostly adopts milk-run distribution and single vechicle point-to-point distribution.However,these two distribution modes have low transportation efficiency and can not balance the task amount of the transport vehicle in the case of large distribution tasks.The material distribution problem of mixed flow assembly line focuses on the scheduling research of multi-vehicle coordinated point-to-point material distribution method.The specific research contents are as follows:(1)A mathematical model for the just-in-time delivery of multi-vehicle materials in the automobile mixed-flow assembly line is established to minimize the line-side inventory of each assembly line,taking into account the multiple constraints of the line-side inventory capacity of the station,the loading capacity of the transport vehicle,and the number of transport vehicles.Based on the predetermined assembly sequence,a multi-vehicle material just-in-time delivery plan is obtained through calculation,including the serial number of the transport vehicle,the number of transport materials,and the departure time of each transport.On the premise of ensuring that the assembly line will not be out of stock,the resources of multiple transport vehicles will be evenly allocated to improve the efficiency of material distribution.(2)Compared with the classical backtracking method,a particle swarm optimization(PSO)algorithm is proposed to solve the just-in-time distribution model of multi vehicle materials in the automobile mixed flow assembly line.The simulationanalysis through standard calculation examples shows that the backtracking method can only effectively solve small-scale examples Material distribution.In contrast,even in large instances,the particle swarm algorithm can quickly converge in a limited time to obtain a material distribution solution that minimizes the the inventory level along the line.Moreover,the total working time and total transportation volume of each transport vehicle are relatively balanced.And the in-transit rate of transport vehicles has also reached a high level,so as to realize the balanced allocation of transport vehicle resources and ensure the just-in-time supply of materials for the mixed flow assembly line.(3)Based on the orthogonal experimental method,the influence of the key parameters of multi vehicle material distribution scheme on the experimental results is explored.Through qualitative analysis and orthogonal experimental verification,it is found that too small a line-side inventory capacity or too few transport vehicles may lead to the inability to find a feasible material distribution scheme.In addition,the number of products to be assembled and the number of work stations also have certain effects on the experimental indexes.