Research On Front Longitudinal Beam Size Recision Control Based On Manufacturing Process Simulation

The white body is assembled by welding the large assembly of the front longitudinal beam assembly,the side wall assembly and the floor assembly.At the same time,the front longitudinal beam assembly is also an important component for energy absorption during collision.The shape structure is complex,the matching surface is more,and the manufacturing quality is high.However,the front longitudinal beam steel has high strength and large thickness,and it is difficult to correct the manufacturing deviation later.Therefore,the manufacturing quality control of the front longitudinal beam assembly has become an industry problem,and domestic and foreign enterprises and scientific research institutions have increased investment in research on the manufacturing technology of the front longitudinal beam.The front longitudinal beam assembly is composed of inner and outer plates,reinforcing plates and functional mounting plates.The material strength ranges from 300 to 600 MPa and the thickness ranges from 1.2 to 3.0 mm.The rebound deformation of the parts is large and the manufacturing is difficult.The multi-station assembly leads to the transmission and accumulation of deviation between the parts and the parts.With the manufacturing factors such as tooling wear,the assembly deviation of the assembly is finally formed.At present,the assembly deviation control method is mainly for the pre-design stage and the quality control of the manufacturing process.The analysis of the pre-deviation is usually carried out under the condition of theoretical values.The part forming problem is not taken into account,and there is a certain gap between the analysis result and the actual situation.In view of this problem,this paper proposes a joint analysis method that combines part formability analysis with assembly deviation analysis.According to the results of the joint simulation analysis,the deviation source that affects the dimensional accuracy is analyzed and diagnosed,and the design quality of the product with the early tolerance is improved.The main research content of this paper:(1)Research on the evaluation method of assembly quality status of front longitudinal beam assembly.There are many important matching faces and mounting holes on the front longitudinal beam sub-assembly.The dimensional accuracy determines the final assembly quality of the front longitudinal beam.The measurement data is analyzed and calculated,and the indicators such as the out-of-tolerance rate,CII index and Cpk are obtained to evaluate the manufacturing quality.On this basis,according to the difference of the degree of attention of different parts on the main line,the concept of key matching index is proposed,and it is hoped that there can be some guidance for the priority order of dimensional precision control.(2)The deviation in the four stages of the assembly process(positioning,clamping,welding and unloading)is analyzed by analyzing the assembly deviation of the front longitudinal beam.Multi-station and multi-step are typical features of the front longitudinal beam assembly,and complex assembly processes must introduce numerous complex deviation sources.By analyzing the influence of the deviation source of different assembly stages on the dimensional accuracy,and establishing the model according to the relevant assembly process,the simulation calculation is carried out.According to the simulation analysis results,the deviation source that affects the dimensional accuracy is analyzed and diagnosed.(3)The dimensional accuracy of the assembly is largely affected by the dimensional accuracy of the part.Through the formability analysis of the parts,the dimensional deviation of the parts manufacturing is obtained.At the same time,the main defects and common measures of the parts are explained,and then the influence of the parts manufacturing defects on the assembly dimensional accuracy is analyzed.(4)Analyze the factors affecting the dimensional accuracy of the front longitudinal beam and perform on-site verification.The dimensional deviation of the part forming analysis is imported into the assembly deviation simulation model and deepened from the rigid analysis to the flexible analysis.According to the results of contribution and geometric factor analysis,the main sources of deviation affecting the dimensional accuracy are determined,and corresponding schemes are developed for simulation verification.Finally,combined with on-site manufacturing experience,on-site rectification,verify the effectiveness of the program.