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.

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.

This paper analyzed the problem of difficult installation of Printed Circuit Board Assembly (PCBA) caused by warping during trial production and identified wave soldering as the key factor through specific test comparison. ABAQUS was applied to perform thermal-structural coupling FEA simulation analysis of wave soldering process, it was concluded that poor temperature resistance of connector base material, large difference in thermal expansion coefficient between connector base material and PCBA material, uneven heating caused by process were the causes of PCBA warpage. Therefore, professional suggestions were provided and a series of verification schemes were developed for verification and improvement, which eventually eliminated PCBA warpage caused by wave soldering.

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%.

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.

In order to promote the development of flat wire motor technologies for new energy vehicles and introduce it into large-scale production, this article studied the paint removal welding process in the manufacturing process chain. A paint removal process plan for flat wire motors was developed. Based on the requirements of product characteristics and combined with the evaluation method of paint removal effects, the article analyzed the correlation between residual organic matter, surface roughness, heat affected zone length, welding pulling force, residual organic matter on the paint removal surface, and clearly defined the RFU value of paint quality within a limited range. By comparing the paint removal effects of different flat wire paint film insulation schemes, the article concludes that the laser paint removal process is adaptable to various insulation schemes, reducing the costs of model change. The article also analyzed comprehensively, guided practice and application of this process plan in aspects of paint removal effects, investment, application and maintenance.

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.

This article studied and analyzed the basic principle of electron beam welding and the main factors affecting welding quality. In combination with the developing project case, this paper, taking the sixth driven gear of a 6-speed manual transmission of a commercial vehicle as the research object, introduced the optimization of welding process parameters and structural design to solve the welding crack problem. The experiment finds that when the welding structure remains unchanged, it is difficult to eliminate welding cracks by changing the process parameters when the welding depth is deeper; Simultaneously optimizing the welding structure and matching it with appropriate welding processes can eliminate welding cracks and meet technical requirements such as welding depth.

In order to improve manufacturing technology capabilities and production preparation efficiency of production lines in the digital era, this article studied the use of industrial simulation PDPS software for virtual process design of automotive door sealing strip rolling (including simulation of production line design, virtual simulation verification of process and equipment). The results indicate that simulation and validation in the virtual environment can verify the rationality of design schemes in advance, identify design problems, optimize design schemes, shorten installation and debugging time, simulation is an efficient means for factories to achieve rapid intellectualization and digital transformation.

With the development of automobile lightweight technology, the substrates of truck body have changed from cold-rolled steel sheet to aluminum alloy mixed with cold-rolled steel, which has brought about the demand for co-line coating of steel and aluminum alloy. Therefore, this paper, based on the tests of the degreasing, surface conditioning, phosphating and electrophores, discussed the pretreatment process scheme of steel-aluminum co-line phosphating. The research results show that the degreasing corrosion of aluminum alloy should be controlled below 100 mg/m² when the co-line coating of steel and aluminum is carried out, and the surface conditioner XG, by contrast, has a more significant effect on the phosphating of aluminum alloy. When the concentration of fluoride ions in phosphating solution is 150~240 mg/L, the corrosion resistance of electrophoresis films on DC04 cold-rolled steel plate, 5052 and 6061 aluminum alloy substrate can meet 1 000 h of neutral salt spray test requirements. The research results provide technical support for the application of steel-aluminum co-line coating technology.