To address the issue of automotive body weld seam sealant bubble, this paper started from the cause of automotive body sealant bubble, it firstly introduced 2 sealant bubble analysis methods including automotive body break-up analysis and section analysis, determined that excessive use of hemming sealant was the cause of sealant bubble, proposed the adjustment of slab gap and hemming sealant to eliminate sealant bubble. The results show that sealant bubble will be eliminated when slab gap is less than 0.02 mm, whereas adjustment of furnace temperature can only reduce the size of sealant bubble, can’t reduce the amount of sealant bubble.

In order to solve the problems of equipment shutdown and environmental pollution caused by the falling of the oxide scale of the hot-rolled strip used in the production of beam parts, this paper took the conversion and switching of EPS steel plate as the main research object, analyzed the causes for the falling of hot-rolled strip oxide scale during the rolling process by means of test verification and genchi genbutsu, analyzed the technical advantages of high surface quality of EPS steel plate and no need for shot blasting after the parts were formed. The paper proposed technical requirements of EPS materials: the yield strength of the steel plate is 530 MPa~560 MPa, the tensile strength is 600 MPa~630 MPa, the elongation after breaking is ≥22%, and the cold bending performance requirements need to be met. The average surface roughness Ra≤5.0 μm after EPS treatment. Finally, it led to the switch of EPS steel plate production.

The fracture of a high-strength bolt used for fixing battery module of a new energy vehicle in the process of vibration test was investigated and analyzed through physical and chemical inspection, assembly process and vibration test. The results of investigation and analysis show that the cause of fracture is the formation of fatigue source caused by improper bolt assembly, the fatigue source continues to expand under the combined action of alternating stress and radial shear force at the upper and lower joint plane of the failed bolt along Z-direction vibration, which eventually leads to fracture.

The First Time Through (FTT) of body outer cover panel is an important index of stamping quality evaluation. Taking the outer plate of aluminum cover as an example, this paper analyzed the problem of pitting and scratches and formulated countermeasures from 5 dimensions of man-machine material method ring. By improving the cleanliness of wire body, equipment and die, the surface state of die and the gap of longitudinal cutting tool of aluminum rolling were optimized, the tension control model of aluminum plate rolling process was adjusted, which reduced the frequency of pitting and scratch defects of aluminum cover outer plate, improved the FTT of aluminum outer cover from 85% to more than 92%.

Due to the fact that riveting technology is mostly applied for aluminum connection, its application in automotive Body In White (BIW) is limited. To solve the issue of compatibility between riveting process and other basic processes, this paper studied the integration of multiple riveting processes, designed a scheme to achieve multiple riveting processes emplying a single robot, validation analysis was conducted. The integration mainly includes self-piercing riveting process, rivetless self-piercing riveting process and rotary tapping riveting process. Meanwhile this paper also objectively analyzed the post-integration of other processes. The validation results indicate that the integration of multiple riveting processes can improve equipment start-up rate, reduce production costs and energy consumption in a single production cycle.

In order to evaluate the weld seam fatigue life of suspension control arm accurately, this paper conducted weld seam fatigue analysis considering the interference fit stress. The interference fit stress of the control arm calculated by theoretical calculation and Finite Element Method (FEM) was compared, the fatigue load was equivalent treated, the fatigue conditions were simplified into three simple conditions. The “VOLVO” fatigue analysis method of weld seam was introduced, the fatigue life of control arm weld seam was checked by this method. The analysis results are in good agreement with the results of bench test, the optimized scheme successfully passes the vehicle durability verification.

Based on the experience of automobile development process, this paper proposed a set of technical solutions for improving the material utilization ratio of automobile parts, which involved the modeling design of parting line, product design, process design and die try out. According to the stamping synchronous engineering analysis and the die try out analysis as well as practical case, this paper compared the solution with the traditional technical solution, highlighting the advantages of the technical solution proposed in this paper. The results show that this solution can effectively reduce the material consumption, improve the material utilization ratio of parts and save the cost of vehicle manufacturing.

To solve the shortcomings of silane film technology in covering ability and adhesion, this paper proposed a method to control silane film weight. Firstly, reduce the risk of excessive film weight by optimizing the start and stop procedures of the silane tank circulation pump, secondly, effectively prevent excessive accumulation of zinc hydroxide on the workpiece surface by selecting appropriate degreasing agents, to improve the adhesion between the silane film layer and the substrate, the problem of insufficient electrophoretic adhesion in the silane film process is thus solved.

A cross beam of instrument cluster was welded automatically. In order to eliminate the influence of weld seam position deviation on welding quality, it is necessary to explore the control method and application of weld seam tracking. Several common control methods of welding seam tracking were studied and compared, laser position identification technology was applied in the automatic welding of commercial vehicle’s instrument panel cross beam. The scheme design, system architecture, working process, using effect and other aspects were expounded in detail. Through the verification of the actual production, the laser position identification technology effectively realized the tracking and positioning of the welding seam. By giving feedback and correcting the movement trajectory of the welding robot, it improved the welding accuracy of the instrument panel cross beam, and provided strong guarantee for improving the assembly quality of the cab interior.

To obtain the optimal milling process parameters of vermicular graphite cast iron, milling test was conducted by using the BP neural network optimization design method at various combinations of cutting speed, feed rate and back feed volume, the chip formation of vermicular graphite cast iron (RU450) and the influence of process parameters on surface quality during high-speed milling was studied and analyzed. The results indicate that the optimal milling process parameters, as optimized by the BP neural network, consist of a cutting speed range of 2.8~3.1 m/s, a feed rate of 760~780 mm/min, and a back feed rate of 0.1 mm. The milling process resulted in chips with a helical and "C"-shaped curved shape, as observed by Scanning Electron Microscope (SEM). The graphite on the workpiece surface has a complete worm-like and spherical shape, with the graphite edge clearly visible. The milling surface roughness measures 1.0~2.0 μm, and the milling samples meet all process indicator requirements.