Integrated die-casting process is increasingly widely applied in the manufacturing of new energy vehicles due to its characteristics such as simplification, high efficiency, lightweight and high strength. However, because of short evolution time, immature and inconsistent design of process routes among various enterprises, there are significant differences both in cost and efficiency. This paper compares the advantages and disadvantages of various process routes and suggests adopting aluminum liquid direct supply scheme, automatic online measurement combined with automatic deburring, and using tapping instead of thread sleeve process as much as possible if conditions permit, which can significantly reduce production costs and improve production efficiency. However, this scheme still has many shortcomings in wide application. By exploring the advantages and disadvantages of process routes used in key processes of various enterprises, more efficient, more economic, high quality and stable process route are summarized deeply.

In order to improve the quality of automotive DTS, a multi-level local datum system tolerance design is established on the vehicle body assembly according to the requirements of the whole vehicle DTS goals. By introducing local datum virtual fixtures in the 3D tolerance analysis software 3DCS, parts are assembled into different datum systems, and the tolerance correlation relationship between each level datum is established, achieving the rationality verification of the datum tolerance design at each level of the vehicle body. And the analysis results are incorporated into the design of the vehicle’s Coordinate Measuring Machining(CMM) and chimeric check fixture, as well as the requirements for testing tolerances, to ensure the rationalization of the evaluation of the manufacturing deviation of the vehicle assembly. The vehicle’s DTS goals have been achieved through virtual and real verification.

Based on the complex structure of new energy vehicles, this paper studies the baking simulation technology. In order to solve the baking problems caused by the application of new materials to the coating process and avoid the baking defects in vehicle model launch and production, baking simulation software is used to simulate the coating electrophoresis baking. The paper performs synchronous engineering analysis, guides and evaluates the scheme of drying room renovation, and provides feasibility assessment and parametric suggestions.

In order to achieve intelligent predication of magnesium alloy die-casting parts, reduce offline labor inspection cost, and improve intelligent level of magnesium alloy die-casting industry, this paper collects big data on “process parameters-quality parameters” of large thin-walled magnesium alloy castings, and uses random forest model to establish the relationship between process parameters and the types of defects in castings, and analyzes the effect of long-tailed distribution of labels in the industrial data on the predictive performance of machine learning models. Then the “Random Downsampling + SMOTE Over-sampling” algorithm is emptoyed to balance the distribution of the data set. Finally, an accurate prediction model with an accuracy of 89.54%, an area under ROC curve of 0.983 8, and an average true rate of 87.65% are obtained, which achieves a precise detection of a small number of defective samples, and obtains the ranking of the importance of key process parameters for magnesium alloy casting.

To improve the internal quality and mechanical properties of magnesium alloy die-casting parts, this paper studies the influence of high and low speed switching position on the internal porosity and mechanical properties of AE44 magnesium alloy die-casting parts. The results show that compared with the traditional position of the punch when the alloy liquid reaches the inner gate as the high and low speed switching position, advancing the high and low speed switching position can reduce the porosity inside the casting and improve its mechanical properties. However, advancing the high and low speed switching position too much can actually increase the porosity and decrease the mechanical properties. That is mainly because advancing the high and low speed switching position can reduce the melt temperature drop of magnesium alloy during the filling process, which is beneficial for improving the fluidity of magnesium alloy and the discharge of residual air in the mold cavity. If the high and low speed switching position is advanced too much, it will increase the turbulence level when the melt fills the mold cavity, entrain more gas, and improve the porosity of the casting.

In order to improve veatherstrip odor of vehicles, this paper studies automotive weatherstrip odor test method and evaluation standard, compares the test standard of different OEMs and world mainstream organizations, analyzes and summarizes the current standard system. Moreover, the causes of weatherstrip odor and improvement measures are discussed. This paper also proposes improvement schemes from perspectives of material selection and optimization in the mixing process, use of water-based paint in the production process, and appropriate increase of storage temperature in the storage process.

To investigate the effect of electrical parameters and electrolyte concentration on the properties of Micro-Arc Oxidation (MAO) coatings on magnesium alloys, Mg-Zn series magnesium alloys are used as the research substrate. Silicate-based electrolyte is employed to prepare MAO coatings on the surface of the magnesium alloy. By varying the electrical parameters and electrolyte concentration, this paper studies the influence of different parameters on the performance of the MAO coatings. The results show that with the increase of voltage and duty cycle, and the decrease of frequency, the energy provided increases, leading to an accelerated coating growth rate and an increase in coating thickness. With the increase in current density, the coating thickness initially increases and then decreases, as the effect of current density on coating thickness depends on the growth rate and reaction time. The coating thickness is directly proportional to the electrolyte concentration; however, excessively high electrolyte concentrations can cause localized ablation, resulting in coating detachment. The MAO coatings significantly enhance the corrosion resistance of the magnesium alloy, and both increased coating thickness and reduced pore size can improve the corrosion resistance. MAO samples immersed in a 3.5% sodium chloride solution for 120 h exhibits a corrosion rate of 0.24 mm/a. A composite coating of MAO followed by electrophoretic deposition is prepared on the surface of a magnesium alloy automotive battery case. The MAO coating thickness is approximately 13.7 μm, and the electrophoretic coating thickness is about 25 μm, withstanding a neutral salt spray test for 720 h.

In recent years, thixomolding technology has imparted thriving vigor to the magnesium alloy industry. This paper reviews the development and application prospects of thixomolding technology for magnesium alloys. Firstly, the principle and distinctive advantages of thyroiodin process for magnesium alloys are described in detail. Subsequently, the historical development of magnesium thixomolding machines is summarized, highlighting that China is gradually be coming an innovation leader in the field of large-scale equipment teehnology. Furthermore, this paper analyzes the latest advancements in research on microstructure and properties of magnesium materials utilizing thixomolding technology, and points out that this technology can fully exploit the performance potential of magnesium alloy and effectively reduce casting defects. Beyond the commonly used Mg-Al system, novel semi-solid magnesium alloys are also being researched and developed. Concurrently, magnesium matrix composites by thixomolding have garnered attention due to short process and high performance. Thixomolding technology for magnesium alloys has been applied in consumer electronics, transportation tools, etc., and is gradually expanded to the production of large structural parts, especially demonstrating strong application potential in the field of new energy vehicles.

This study investigates the tensile properties, bending properties, hydrogen embrittlement sensitivity, spot welding performance, and coating corrosion resistance of Al-Si coated thermoformed steel based on vanadium and niobium composite microalloy under typical hot forming processes. The results indicate that under heating temperature of 930 ℃, heating time of 300 s and holding time of 10 s, the experimental material achieves a tensile strength of 2 000 MPa and extreme tip cold bending angle is greater than 50°, demonstrating a favorable combination of strength and toughness. The mechanical properties exhibit significant anisotropy, with a notable improvement in toughness after baking at 170 ℃ for 20 minutes. The strength and ductility parameters display varying strain rate sensitivities across different strain rates ranging from 0.1 ~ 500 s^-1. In a four-point bending test at 100% yield strength in an air environment, the hot-formed material show no cracks or fractures after 300 h, indicating excellent resistance to hydrogen embrittlement. Additionally, the spot welding performance and coating corrosion resistance of the experimental material meet application requirements.

In order to constantly improve the manufacturing flexibility of Body-In-White production lines and optimize the usable load capacity of industrial robots in welding shops, the paper elaborates the optimization techniques of serial robot tool system under the multi-constraints of engineering retrofit design. In the design of welding robotic non-standardized tool, such as gripper, welding gun and riveting gun, while considering its function structure, reliability and economy, measures are implemented comprehensively according to the process design scheme from dimensions including machine, material, method, measurement and environment, which are verified through simulation analysis and actual measurement, so as to achieve the technical goal of the robotic tool load optimization. Moreover, the practical effects of the optimization techniques in three typical cases are illustrated.