Research On Assembly Deviation Analysis And Optimization Design Method For High-speed Train Body Assembly

The aluminum alloy vehicle body of high-speed train is the main body of the whole train.It is very high of assembly quality and accuracy,because its structure is complex,the size is large,and parts are large.In the assembly process of the vehicle body,various complicated deviation sources will be continuously coupled,transmitted and accumulated,such as part deviation,fixture deviation and welding deformation.These deviation sources take shape of assembly dimension deviation of the body.The size deviation of the body assembly directly affects the traffic safety and service life of the high-speed train,so how to reduce the assembly deviation and improve the quality of the body assembly is the goal of the enterprise.Therefore,the goal of the enterprise is to reduce the deviation of the body and improve the assembly quality of the body.In this dissertation,the main sources of deviation of vehicle body assembly are modeled and analyzed,and the anti-deformation method is used to optimize the assembly deviation so as to ensure the assembly quality of the vehicle body.The main content of this dissertation is as follows:Firstly,the method of assembly deviation analysis and optimization design at home and abroad is introduced,and various sources of deviation of high-speed train body are elaborated in detail.According to the assembly process of high-speed train body,these main deviation sources are analyzed in the assembly process of the vehicle body,such as geometric deviation,welding distortion and assembly sequence.It is proposed that the analysis schemes and optimization methods of various deviation sources of the vehicle body assembly.Secondly,the geometric deviation of vehicle body assembly is studied,and a geometrical deviation analysis method for vehicle body assembly based on homogeneous coordinate transformation is proposed.The vehicle body must be clamped before the welding.Parts are assembled into sub-assembly,and sub-assemblies are assembled into a body assembly,so the inconsistent coordinate system will bring the positioning reference error.A unified vehicle body assembly reference coordinate system is established,and the geometric deviation in the process of assembly and assembly is calculated based on the theory of homogeneous coordinate transformation.Thirdly,a finite element analysis method based on MSC.Marc software for vehicle body assembly welding deformation is proposed by aiming at the problem of welding deformation during car body welding.Through the welding process of vehicle body assembly about high-speed train,two kinds of finite element models of butt joints and lap joints are established respectively with the same proportion as the actual vehicle.After the simulation,to analyze the welding deformation laws of different welded joints will lays a theoreticalfoundation for controlling the assembly deviation caused by the welding process.Forthly,the accumulation of deviations caused by the assembly sequence of the vehicle body was analyzed,and a vehicle body assembly sequence planning method based on assembly constraint evaluation was proposed.It establishes assembly model by analyzing the connection priority relationship of vehicle body welding.Through the shrinkage algorithm,sub assembly recognition algorithm and assembly evaluation conditions,automatic assembly bias and feasible assembly sequence can be generated automatically.According to the assembly sequence,the composition calculation of assembly deviation cumulative composition calculation is carried out to verify the rationality of the car body assembly deviation analysis method.Finally,the theory of inherent strain and the principle of anti deformation are applied to infer the deflection curve equation of the inverse deformation method before welding.The free welding model and the anti-deformation welding model were established for the aluminum alloy profile of the vehicle body as the research object.The two models were numerically simulated by MSC.Marc software.The two models were simulated by MSC.Marc software.The displacements of the two welding methods in the Y direction were extracted and the welding anti-deformation method was used to optimize the assembly deviation of the vehicle body.