| The Electric Multiple Units(EMU)car body is regarded as a composition of the multi-powered vehicle group and transportation for passengers.The major target of China Railway High-speed is to realize high-speed,safety,comfortable condition and lightweight design.However,the deviation of EMU car body is the general problem in manufacturing industry of EMU car body,resulting noises,bad airtightness and stability.These deviations of manufacture are mainly caused by changeability of large flexible panel,reference error in EMU car body assembly process,unstable welding fixture,deformation of welding and interference of components' assembling.These deviations can lead to a comprehensive deviation in the manufacture of the EMU car body,due to the coupling,accumulation and propagation occurring during its assembly.(1)Analyzing the necessary resource and research on assembly deviation of EMU car body,discussing the current research status on assembly deviation of EMU car body and the problems of deviation which need to be resolved,all these form the general framework of this paper.(2)The geometrical deviations are divided into three layers about EMU car body assembly,component assembly and workpiece assembly,through analyzing welding crafts of EMU car body and the factors that affect the assembly deviation.(for instance geometric deformation in body assembly process,welding deformation and welding joints,etc)Then,these different layers can be used for setting up reference coordinate system of EMU car body,assistant coordinate system of components and partial coordinate system.The coordinate date will be changed by accumulation and spreading of deviation of EMU car body assembly based on reference coordinate system.The geometric deviation model of EMU car body assembly will be established by the changeable theory of homogeneous coordinate.(3)As for the difference function of components and Structural differences,welding plugs are divided into five types by analyzing the thermal deformation error in assembly process.Welding plugs can be divided into two kinds of butt joints and overlap joints,and are established welding deformation model with two welding plugs.Analyzing what effect will two different plugs produce on four materials:weather steel,stainless steel,aluminum and magnesium alloy.The rationality of welding deformation has been proved by using ANSYS software simulates welding deformation of butt joint.(4)Based on the PERT diagram,we analyze the relationship of EMU car body assembly,and put out the relationship among all components.The experiment is given to analyzed a type of EMU real model designed by Autodesk Inventor 3D modeling software.We can obtained body assembly deviation by geometric deviation and thermal deformation deviation in interactive bodies,and prove that the geometric deviation and accumulation of thermal deformation accord with the design requirement. |
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