Analysis of Errors in Assembly of Automotive Flexibility Facilities

The car body is assembled from 300 to 500 flexible sheet stamping parts. Any positioning, clamping, and other processes in the assembly process may cause the part to undergo dimensional changes. The error of each assembly level accumulates to form the vehicle body manufacturing error; The Carlo simulation method is theoretically the most perfect method for studying complex car body assembly errors. It uses random numbers and part assembly functions to analyze assembly errors, but the process is complicated and time-consuming, and it is difficult to obtain a wide range of car body assembly error analysis. application. Therefore, there is a need to establish a new method that is suitable for analyzing the assembly error of body flexible parts. In 1980, Takezaw a pointed out that according to the research on flexible thin-plate assembly of automobile, “The error accumulation theory based on rigid body assumption is difficult to apply to the assembly of stamping parts of car body flexible thin plate. The assembly error can be smaller than the part deviation and close to the rigidity. Parts.” In the early 1990s, the University of Michigan took the lead in initiating a systematic theoretical study on the assembly error of body parts for flexible parts, and in the United States, automobile manufacturing has changed in space, rather than welding nodes 22 and 27, 24 and 29. Keep your movements independent of each other.

According to the thin-plate assembly mechanics analysis described above and the finite element meshing of Fig. 5, the average assembly deviation of the examples is solved.

The original 1 mm part deviation of the two thin-plate parts is constrained by the welding spot fixing and the clamping force of the fixture, so that the deviation propagates, couples or accumulates in the plate and is redistributed. The average deviation of the assembly is less than the deviation of the part, and the plate with greater rigidity is larger. The deviation of the thin plate with less deviation than the stiffness is small, that is, when large and small stiffness parts are assembled, the deviation of large rigidity parts is the main source of assembly deviation.

3 Conclusion The car body assembly is a complex level assembly process, and its integrated manufacturing error is the result of error coupling, accumulation and propagation caused by various factors such as part deviation, welding deformation, fixture deviation and operation difference. The geometrical properties of the car body parts and the mechanical relationship of the weldment will directly affect the manufacturing error. Because the vehicle body is the carrier of the stamped parts of each flexible sheet, the cumulative theory of rigid body assembly errors is difficult to apply to the analysis of vehicle body assembly errors. The finite element method is used to analyze the assembly error of flexible parts. It is the development direction of researching the manufacturing error of the car body. The results can further help to optimize the solder joint layout. The research shows that when large and small rigid parts are assembled, the deviation of large rigid parts is the main source of assembly error, and the series assembly error in the body manufacturing process is greater than that of individual parts, and the parallel assembly error is smaller than the part deviation.