To deal with the limitation of the existing non-destructive testing technology for the depth of the carburized layer of axle steel, a weak magnetic detection method is proposed. Since the stress concentrates at the junction of the carburized layer and its heart and can’t be eliminated, and then externally show a specific magnetic induction intensity for non. By collecting magnetic field signals from different samples of axle steel and different parts of axle steel, we analyzed the corresponding relationship between magnetic induction intensity amplitude and depth, and constructed a mathematical model for weak magnetic detection. The test results show that: spline outer circle (standard thickness/inspection thickness/absolute error): 3.50 mm/3.57 mm/0.07 mm; rod outer circle: 4.30 mm/4.46 mm/0.16 mm; R-angle: 4.00 mm/3.86 mm/-0.14 mm. The overall relative error of the inspection accuracy is less than 5%, which meets the actual needs of the factory inspection.

Since the line has to be stopped when replacing the electrode tip, the Overall Equipment Effectiveness (OEE) improvement of the automatic production line and manufacturing cost of per vehicle will be affected directly. To address this issue, this paper analyzed the electrode tip replacement time and frequency, used the linear programming model method to build a data replacement analysis model, summarized the risk level of replacement in different scenarios according to practical experience. At the same time, the standardized method of “fixed person, fixed time, fixed station” was implemented, and the final solution was determined after repeated iterative adjustment. After the grouping electrode tip replacement according to this strategy, the replacement frequency and time of electrode tip in the production line area has been reduced, and the overall OEE index has been significantly improved. At the same time, the cost of unit vehicle auxiliary materials was also optimized.

At present, most of the powertrains of medium and large luxury cars adopt the form of longitudinal engine rear-drive. Based on the assembly of a luxury brand vertical engine structure in the engine pre-assembly line of the assembly workshop, a specially designed engine carrier lifting fixture was used to realize the process installation of the parts. The lifting fixture was used to simultaneously lift the engine and transmission as well as the front axle assembly on the pre-assembly line, and automatically move the suspended integrated lifting fixture assembly and the workpiece on the pre-assembly line by carrying lifting fixture, thus completing the process installation of the parts. This paper discussed the application advantages and functional characteristics of this engine pre-assembly line process planning scheme and engine carrier lifting fixture for simultaneous suspension of multiple large mass parts, then introduced cases of lifting fixuture optimization.

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.

To ensure the calculation depth of the weld seam, reduce the heat input and improve the welding speed, a double-wire MUP welding method was developed for robot double-wire welding of the heavy truck axle. 4 welding control modes were developed, which were analyzed and compared in aspects of arc stability, heat input and waveform control. Mode 1 is front welding wire pulse welding plus rear wire Mixed Up Pulse (MUP) welding, Mode 2 is front wire MUP welding plus rear wire pure pulse welding, Mode 3 is MUP welding for both front and rear wires, front wire pulse corresponds to rear wire pulse and front wire DC corresponds to rear wire DC, mode 4 is MUP welding for both front and rear wires, front wire pulse corresponds to rear wire DC and front wire DC corresponds to rear wire pulse. When welding the axle longitudinal seam V-shaped groove, the use of Mode 1 can obtain consistent weld seam calculation depth, reduce the heat input, improve welding speed and obtain graceful weld seam appearance; Mode 2 is more suitable for rapid welding of thin plates, the use of Mode 3 can significantly reduce heat input to obtain graceful weld seam, improve arc stability and welding speed when welding axle reinforcement ring and rear axle housing, and Mode 4 is suitable for the welding of thick plate filling layer, which can stir the molten pool to promote rapid gas overflow and reduce the tendency of porosity in the weld.

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.

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 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.

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.

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%.