Robust Design And Analysis For Typical Two Types Assembly

Due to the existing of factors such as dimensional deviation,machining deviation,positioning deviation,and production noise in the product processing system,the quality of product assembly is affected inevitably,This paper mainly studies the influence of various bias factors in the two types of assembly process.The Type1 assembly predicts the global assembly of the product with the gear assembly as the object,and performs a robust tolerance design based on the product's global success rate model.The Type2 assembly predicts the deviation of the sheet metal assembly from the body floor and makes a robust design for the sheet metal assembly process layout.By predicting the assembly accuracy or assembly success rate of the two types of assemblies,the product manufacturing process is optimized based on robust design to improve product assembly quality.the main work are as follows:Global assembly yield modeling and tolerance robust design based on part mating features.First,based on probability statistics,the part processing success rate calculation model is established.Combined with the onedimensional multiprocess assembly success rate calculation model,a multistep global yield calculation model is proposed.Combined with the model of machining yield,a multistation overall yield calculation model is put forward.The goal is to minimize the sensitivity.The overall yield,machining allowance standard deviation and mean shift are taken as constraints,a tolerance robust design model for multistation manufacturing process is established.At the same time,the simulated annealing algorithm is used to calculate the robust tolerance design.Finally,taking gear assembly as an example,the overall yield of gear assembly is calculated,and a corresponding tolerance robust design model is established,and the model is calculated and analyzed.Modeling and analysis of comprehensive deviation of sheet metal assembly based on fixture positioning.The process of sheet metal assembly is expounded,and the influence of parts key measurement point deviation,fixture locating deviation,welding gun deviation,welding gun release and overpositioning chuck release on compliant sheet metal assembly deviation during the sheet metal assembly process under overpositioning conditions is analyzed.Sheet metal assembly comprehensive deviation model is established based on displacement relationship and finite element analysis.Finally,taking the underbody assembly as an example,the linear relationship analytic expression between the key measurement point deviation and the fixture positioning deviation,the welding gun deviation,the welding gun release rebound,and the over positioning release rebound is established according to the assembly deviation model,the deviation distribution characteristics of key feature points on the assembly is obtained combined with Monte Carlo method.Based on the Taguchi orthogonal experiment design,a method of the robust design of the layout of the sheet metal assembly process is presented.First of all,with the example of the autobody floor assembly,the influence of the coordinate value of the fixture positioning parameter on the assembly deviation of the sheet measurement point is analyzed under the “421” locating principle,and the fixture locating parameter level is designed with this.Then,the Taguchi orthogonal experiment is arranged considering the fixture locating position and the welding point position as the design parameters and the part manufacturing deviation,the fixture positioning deviation and the welding gun deviation as the noise factors.The evaluation function indicating the robustness of the assembly quality is established using the critical measurement point assembly deviation as the measuring index of assembly quality.The calculation method of the signaltonoise ratio of the flexible sheet assembly fixture layout and the stable layout of the solder joint layout is proposed.Finally,the robustness of the assembly quality to the various deviation factors under different fixture locating layouts and welding point layout schemes is analyzed,and a robust assembly process layout scheme is determined,combined with the sheet metal assembly deviation model.