This paper discussed the determination of hexavalent chromium content in automobile materials and its uncertainty evaluation process based on colorimetric method. Hexavalent chromium in automobile materials was determined by UV spectrophotometry with a pretreatment method of lye digestion, and the uncertainty of measurement results was evaluated. A mathematical model is established to analyze and discuss the source of uncertainty measurement, calculation and result representation. The results show that the preparation process of standard solutions, measurement repeatability and calibration curve fitting quantification are the main contributors to the uncertainty of measurement results, which should be paid attention to in the testing process.

Due to the poor wettability and thermal stability of electrolyte, the application of traditional lithium ion battery separator in the field of high-performance and high safety battery is limited. The surface modification of the separator to realize its surface functionalization has become a feasible strategy to solve the inherent problems of lithium-ion battery separators. From perspective of surface physical modification and surface chemical modification, this paper elaborated respectively the features and cutting-edge dynamics of various surface modification methods, such as spray coating, dip coating, solution casting, electrospinning, chemical grafting, plasma, radiation grafting and UV grafting. The paper also indicated that developing multifunctional separators, intelligent response separators, and reducing modification costs would be the research directions for surface modification of lithium-ion battery separators in the future.

Based on the exploration of the application of aluminum alloy in automobile parts, the basic situation of aluminum enterprise distribution, aluminum alloy composition elements, properties and processes are summarized. The commercialized application of aluminum in automobiles, especially in car bodies, is summarized. This paper proves the superiority and applicability of aluminum in automobile application, and summarizes the common methods of connecting aluminum parts with different and same materials. Research shows that the research and development of high-performance aluminum needs to be strengthened compared to foreign companies, and the diversification of automotive materials is constantly expanding in the field of lightweight, but the application of aluminum is still mainstream.

This paper elaborated the current situation of the application of aluminum alloy integrated die casting technologies in new energy vehicle enterprises and the planning of integrated die casting in mainstream new energy vehicle enterprises, it is concluded that the integrated die casting technology has obvious advantages in production efficiency, cost reduction, weight reduction and other aspects, and die casting machine will replace the welding robot as the core equipment of new energy vehicle manufacturing. It also indicates that the core of the integrated die casting technologies is the performance of large die casting machine, the formula of heat-free material, die casting die design and die casting process parameters. The research result shows that aluminum alloy integrated die casting will replace the manufacturing technology of body stamping and welding, the paper recommends that new energy vehicle enterprises that do not use integrated die casting should plan the integrated die casting technologies in advance.

This paper discussed the product process design and welding defects debugging method of the laser brazing for the roof of Body In White (BIW) based on the industrial practice and application of the laser brazing of the BIW roof in Dongfeng Honda Automobile Co., Ltd., and focused on product structural design of the laser brazing of roof, component dimension accuracy control, production line process planning and plane layout of roof laser brazing, welding defects debugging method, manual inspection and repair process. By comprehensive introduction of process design and defect debugging method of laser brazing for BIW roof, the paper provided technical reference of laser brazing product design and process planning for subsequent new vehicle roof.

This paper elaborated the anti-loosening method of adjusting nuts for automotive rack and pinion steering gears, and studied the riveting point method using riveting head to damage the threads of adjusting nuts. In this paper, the number of riveting head, the distribution of riveting head, and the riveting pressure were used as control variables, and the loosening torque of the adjusting nut after riveting, the deformation of the pressure block hole of the steering gear housing were utilized as evaluation indicators. According to the test, when 6 riveting heads are evenly distributed on the pitch diameter circle of the adjusting nut thread circumferentially to rivet the steering gear nut, the deformation of the pressure block hole of the housing is less affected, and the locking torque of the adjusting nut is also less affected. Finally, the method of adjusting nut riveting point for steering gear is obtained, in which 6 rivet heads are uniformly distributed on the pitch diameter circle of the adjusting nut thread along the circumferential direction, with riveting pressure of 30 kN riveting pressure as optimal.

To enhance the product maturity and solve the problems found in manufacturability analysis, product manufacturability baseline and mechanism were established. The first version of baseline was established through clarifying the scope, developing template, identifying source, confirming dimension, refining content, process confirmation, design confirmation, release and maintenance. Relevant activities such as identification, analysis, evaluation, and accumulation were integrated with the product development process to ensure the procedural application of baseline in the project. Combined with the product development project, the effect of baseline establishment and application were verified, improving the standardization, accuracy, and comprehensiveness of manufacturability analysis, improving product quality and production efficiency, as well as reducing manufacturing costs. At the same time, future expectations for the digital application of baselines were proposed.

In order to eliminate surface defects around the roof antenna mounting boss, this paper used Autoform simulation and experimental verification to analyze 2 causes of defects, cause 1: stroke during the forming process is small, and the plastic deformation of the material is insufficient; cause 2: the pressing force of the pressing plate is insufficient, resulting in the deformation in the deformation area affecting the non-deformed area. Through the simulation analysis of the 2 process methods of the antenna mounting boss drawing forming and upper forming, it is confirmed that the upper forming process can effectively solve the defect around the antenna mounting boss, and the real effect is completely consistent with the theoretical simulation, which solves the problem of the surface defect of the antenna boss.

This paper discussed the rationality of structural technology design of the parts from the aspects of modeling feature, slope and rounded corners, proposed precautions for process surface design from aspects such as process surface construction and settings, elaborated on blank design to solve the problem of low material utilization rate through laser cutting and layout, the paper also elaborated on the development risks and control involved in hot stamping formability analysis from CAE simulation process. The paper explored the hot stamping forming process technology involved in the development process of integrated door ring from the above 4 aspects, providing reference experience for the development of integrated door ring process technology, in order to solve the relevant problems in the development process, and also better reduce its development cost and shorten its development cycle.

To meet the development needs of commercial vehicle light weight, from the perspective of materials light weight, the original glass fiber composite deflectors were replaced by Carbon Fiber Reinforced Plastics (CFRP) deflectors, It is achieved that the weight is reduced by 30% and the performance index is consistent, and even better. Based on the composite material failure criterion of 3D-Hashin and Cohesive layered failure criterion, a simulation model of basic mechanical properties of CFRP was established, and the effectiveness of the model was verified by comparing with experimental results. through the design of CFRP layer angle, finite element modeling was founded, the modal performance and stiffness of the 2 materials deflectors were compared and analyzed, the results show that the theoretical quality of carbon fiber reinforced plastics (CFRP) deflectors model is reduced, at the same time, compared with the original glass fiber composites deflectors, the modal performance and the average stiffness increase, and meet the fracture strength requirements.