The D-Arc deep penetration welding process was applied to the straight joint welding test of 12 mm-thick axle housing of commercial vehicles, and the weld profile, welding thermal cycle and residual stress were measured and analyzed. Based on Simufact Welding software and combined with the profile shape of the welded joint, a finite element analysis model for straight seam welding of the axle housing was established. A composite heat source model of Gaussian surface heat source and cone heat source was adopted to simulate the heat input in the D-Arc deep penetration welding process, and the process of straight seam D-Arc deep penetration welding was numerically simulated. The temperature and stress distribution of the axle housing at different times were obtained, and the simulation results were basically consistent with the test results, which verified the reliability of the finite element analysis model, and also proved the feasibility of D-Arc deep penetration welding process in the welding scene of commercial vehicle axle housing.

In order to solve the problem that the program structure of the original offline inspection management system is not suitable for the full process monitoring of production information and cannot provide efficient production traceability for vehicles, the original EOL platform has been upgraded and developed. The upgraded platform has the characteristics and functions of traditional EOL inspection equipment and is a vehicle electrical inspection data interactive system that runs through various stages of product research and development, production manufacturing, and after-sales. In the production and manufacturing process, the system provides warning information modules, parameter modification modules, etc., which facilitate engineers to quickly analyze and handle on-site flashing issues and avoid production downtime. The entire system meets the needs of personalized customization, intelligent manufacturing, and digital transformation.

To address the issue of difficulty in designing and producing aluminum plate rear door inner plate caused by poor formability and ductility of aluminum plate material, complex shape of rear door inner plate, this paper introduced the simulation analysis of the formability of aluminum plate back door inner plates theoretically based on AutoForm finite element software. Through simulation analysis of different solutions, the final forming solution was determined which guided on-site production, and was verified in on-site debugging.

In order to solve the problem of poor welding quality and frequent falling off of aluminum studs for a vehicle, this paper simulated the magnetic field and electromagnetic force generated in the welding process by ANSYS software, and confirmed the cause was magnetic blowing generated by the deviation of the welding arc caused by the influence of ferromagnetic substances during the welding process. Test confirmed the measures of reducing welding current to reduce magnetic blowing and put into practice. The results show that reduction of welding current can effectively solve the problem of welding stud falling off, relevant rules are summarized, which provide reference for welding stud welding of subsequent vehicle models.

In order to address the issue of low automation and digitalization of the automotive body wax filling process, this paper discussed feasibility of total process automation from production, inspection to repair in automobile wax filling, and proposed an automatic solution of automobile wax filling. In the production process, the body wax filling was realized through technological transformation by the application of low cost automation. In the inspection process, visual identification technology was used instead of manual inspection to capture and identify the wax mist on the vehicle body and reduce the body defect outflow rate. In the repair process, through the analysis of the wax defects, the auto body bottom plate purge device was designed to eliminate the wax overflow on the premise of meeting the performance requirements of the vehicle. In addition, the paper also proposed the data interconnectivity scheme. The results show that the production efficiency and cost have been greatly improved through the application of automation.

It is concluded in this research that strength and toughness of steel can be significantly improved by precipitation strengthening and fine-grained strengthening after adding trace alloying elements of V, Nb and Ti in steel and combining with C and N in steel. Based on the thermodynamic calculation software, the V, Nb and Ti composite microalloying design of non-quenched & tempered 46MnVS6 steel was realized. At the same time, the rolling heating process dissolved the liquid phase of the large particles and realized the high strength design of the material. In addition, the special slag system of non-quenched & tempered steel with low and medium basicity was developed through the simulation calculation of refining slag system, which ensured the precise control of S element in the refining process. The results show that non-metallic inclusions control in non-quenched & tempered steel and the sulfide morphology are optimized, and cutting performance of the material is improved.

In order to determine the fracture mechanism and cause of the trunk lid torsion bar spring, the fracture morphology, composition, size, material strength, microstructure and residual stress were tested, and a comprehensive analysis was conducted in combination with background information. The results indicate that the torsion bar spring of the trunk lid experienced high-strength steel delayed cracking at the concentrated bending stress caused by high material strength, insufficient tempering, and high residual stress. Based on the cause of cracking, improvements were made from two aspects: controlling the strength of raw materials and optimizing the stress relief tempering process to reduce residual stress, and ultimately the delayed cracking failure of the luggage torsion bar spring was effectively solved.

To address the issue of perceived quality in the appearance of vehicle gaps, this article mainly described the content and application of dimensional engineering in the entire product development life cycle of automobiles. The user’s perspective was introduced and a Dimensional Technical Specifications (DTS) setting approach balancing objective numerical values and subjective user perception was constructed. Virtual evaluation technology was applied to ensure the rationality of DTS settings. A refined engineering and visual evaluation standards was established to achieve a practical vehicle effect that balanced design intent and craftsmanship, aiming to find a suitable balance between cost and quality, and thus achieving quality objectives.

In order to improve working efficiency, operation accuracy and safety, and reduce the error rate, based on the automatic spindle equipment, after the engine is connected to the gearbox, the servo motor of the spindle equipment automatically rotates the engine pulley to drive the crankshaft flywheel group to rotate. The high precision rotation of the servo motor ensures that the flywheel and the coupler are connected and fastened after the flywheel and the coupler are connected and fastened, and the coupler is rotated and fastened by automatic equipment to replace the traditional manual operation, which saves manual cost of connecting flywheel with coupler, and can precisely implement the spindle operation. The engine flywheel disc is fixed by the automatic clamping mechanism on the device, which solves the problem of affecting the operation efficiency of the disc shaft due to shaking in the process of lifting the engine disc shaft, and improves the success rate of coupler tightening.

To address the interference of Liquid Apply Sound Deadener (LASD) robot nozzle block on parts installation in the assembly shop, this article analyzed LASD robot nozzle block. Through studying the LASD robot nozzle block times and equipment downtime of paint shop, the root cause of nozzle block was the high robot inlet gluing pressure and short material surface drying time. The LASD robot nozzle block time was reduced effectively by reducing robot inlet gluing pressure and adding gasket to material package, which reduced the risk of faulty car body going to assembly shop to the maximum, and reduced equipment and personnel manpower cost, which effectively reduced the cost from paint shop equipment downtime caused by abnormal gluing status. Meanwhile, it can also shorten the time of production line downtime and car body offline rework that caused by LASD interference in assembly shop.