To optimize the thermal shrink fitting process of the stator core and housing in new energy electric drive systems and improve the qualification rate of thermal shrink fitting, a systematic study is conducted on key issues such as heating temperature, assembly accuracy, heating uniformity, and core rebound in the process. The results show that after housing heating, changes in the positioning hole spacing due to "thermal-structural coupling" led to axis offset, and a diamond pin positioning compensation scheme is proposed. By optimizing the heating process and Proportional-Integral-Derivative (PID) control, heating uniformity is improved. The stress-strength interference model is applied to verify the reliability of the assembly gap. In response to core rebound, the dwell time is optimized, and spray cooling is introduced, effectively enhancing cooling efficiency and dimensional stability. Practice has shown that the related measures significantly improve the qualification rate and production efficiency of the assembly process.

With the expansion of commercial vehicles in both domestic and international markets, the quality problem of threaded fastener loosening has become increasingly prominent due to changes in their operating conditions. Focusing on the common loosening forms of threaded fasteners in commercial vehicles, this paper analyzes the loosening principles and influencing factors, and puts forward corresponding optimization suggestions and measures, so as to provide solutions for the anti-loosening design of threaded fastener connections and the treatment of loosening-related quality problems in commercial vehicles.

To investigate the properties of laser spiral spot welded joints of galvanized steel sheets with different spiral trajectory diameters, experiments were carried out on two lap joint configurations: a 0.7 mm and 2.5 mm large thickness ratio lap joint of galvanized steel sheets, and a three-layer thin galvanized steel sheet assembly with a thickness of 0.7 mm. For each configuration, three groups of tests were designed, including resistance spot welding and laser spiral spot welding with spiral trajectory diameters of 6 mm and 8 mm, respectively. After welding, the welded joints were analyzed from the perspectives of macro-appearance, metallographic microstructure and shear mechanical properties, so as to study the differences of laser spiral spot welded joints under different spiral diameters. The results show that the surface quality of laser spiral spot welded joints is relatively poor, and there is no significant difference in the surface quality of laser spot welded joints with different spiral trajectory diameters. However, the shear resistance and energy absorption capacity of the welded joints are significantly enhanced with the increase of laser spiral trajectory diameter, which proves that the spiral trajectory diameter has a great influence on the mechanical properties of the welded joints. Compared with resistance spot welding, laser spiral spot welding is superior in plastic deformation capacity and energy absorption performance.

To improve the first pass yield rate of polish line in an automobile paint shop, this paper focuses on the critical top coat defects such as crater, other paint, paint runner, solvent spot and paint sludge. The research diagnoses the root causes of various defects systematically through Manufacturing Report System (MRS) quality analysis system and "human, machine, material, methodology, environment" real reason analysis method combining infrared spectrum, element analysis and production verification. There are some targeted countermeasures to solve the defect issues such as changing the fluorine-containing lubricating grease of high temperature zone, optimizing top coat color sequence, strengthen equipment pre-maintenance, adjusting process parameter and changing fault part. The first pass yield of polish line increases from 79% to 91% and the average daily line downtime is reduced by 62% due to the countermeasures implementation. The research shows that systemtic root cause analysis and precise process impoovements are the key to enhancing coating quality and production efficiency.

In this study, the modified HA1-H materials are studied by adding different contents of Fe and other impurity alloys. Through the targeted design of components and processes, the mechanical properties, microstructure and corrosion properties of the produced test plates are experimentally analyzed. Based on the 0.5% Fe material characteristics and product design structure, the fluid state and solidification simulation of the rear floor of a model of ZEEKR are carried out, and the production and analysis are carried out in combination with the design process. Research shows that heat-free high-pressure die-casting aluminum alloy with 0.5% Fe element content can meet the performance requirements of automotive rear floor products.

Driven by the rapid iteration of New Energy Vehicle (NEV) technologies, significant changes in thermal management operating conditions of NEVS, Which has promoted innovations in the materials and structures of cooling hoses. Based on the background of the automotive industry's transition to new energy solutions, this paper first systematically analyzes the core application requirements for automotive cooling hoses across 3 dimensions: performance, cost, and lightweight. Subsequently, it comprehensively reviews 4 categories of typical cooling hose technological solutions currently in mainstream application or under development. Finally, it provides a prospective outlook on the development trend of cooling hose technology for new energy vehicles.

To address the requirements for flexible transportation and precise assembly of multi-size battery packs of new energy vehicles during the final assembly process, a flexible transfer solution for battery packs based on a double-layer roller bed conveyor system has been researched and developed. This solution adopts a skid design with adjustable limiting blocks, and combines a T-type transfer machine, automated guided vehicles, and an overhead buffer system to establish a full-process conveying system covering battery pack loading, buffering, offline assembly, and empty skid return. By integrating Radio Frequency Identification technology and a Manufacturing Execution System through a PLC control system, accurate synchronization between battery pack information tracking and production queues is achieved. Implementation results show that the system can realize overhead buffering of 40 battery packs, improve the workshop space utilization rate by more than 30%, and achieve a battery pack loading accuracy rate of 99.5%. It can ensure continuous supply for 40 min under a production rhythm of 60 JPH (Jobs Per Hour). This conveying solution provides effective technical support for the mixed-model production of new energy vehicles.

Alloying is one of the key approaches to improve the mechanical properties and thermal resistance of SiMo ductile iron. This paper reviews the effects of alloying elements on the microstructure and properties of SiMo ductile iron. A systematic study on multi-element alloyed SiMo ductile iron was carried out targeting exhaust manifolds of high peak-pressure diesel engines and gas engines. The results show that when the mass fraction of Mo increases from 0.9% to 1.46%, the volume fraction of carbides in the microstructure rises, leading to increases in the tensile strength, yield strength and hardness of SiMo ductile iron, while the elongation decreases by 50%. Vanadium alloying elevates the tensile strength but reduces the elongation of SiMo ductile iron; the material achieves satisfactory room-temperature mechanical properties at a V mass fraction of 0.4%. The short-term tensile strength at 800 ℃ increases with the rise of V content, yet no significant change is observed when the V mass fraction exceeds 0.4%. Among the multi-element alloyed SiMo ductile irons, the V-Nb alloyed SiMo ductile iron reaches a high-temperature tensile strength of 59 MPa, while the V-Cr and V-Nb-Cr alloyed variants exhibit high-temperature strengths of 61~64 MPa. These values meet the high-temperature tensile strength requirements for SiMo ductile iron applied in exhaust manifolds of high peak-pressure diesel engines and gas engines.

The differences in humidity resistance between synthetic fiber filter materials and traditional wood pulp fiber filter materials are systematically evaluated through static and dynamic moisture absorption tests, and the intrinsic mechanism underlying the variation in intake resistance of filter materials under high-humidity conditions is investigated. The results show that synthetic fiber filter materials are significantly superior to traditional wood pulp fiber filter materials in terms of dust holding capacity, initial filtration accuracy and full-life filtration performance, while exhibiting lower intake resistance and more stable structural characteristics. In bench tests under humid environments, synthetic fiber filter elements demonstrate excellent humidity resistance without obvious structural deformation or intake resistance rise. Further drum bench test results indicate that synthetic fiber filter elements can reduce the intake resistance by approximately 20% under high-humidity conditions, improving fuel economy by 1%. In addition, the 60,000 km on-vehicle test verified that synthetic fiber filter elements achieve a remarkable fuel-saving effect, which confirms their performance advantages in practical applications.

To solve the defects of the engine cylinder bore thermal spray materials, namely the brittle fracture of welding wire, the peeling of copper plate layer, and the coating holes, the defect mechanism is clarified through microstructure analysis and full-process process optimization, and corresponding countermeasures are formulated. The results show that the brittle fracture of the imported material is caused by the large amount of hard bainite resulting from composition segregation, which causes cracks during drawing. The electromagnetic stirring, light pressure reduction and "air cooling + slow cooling" process can effectively inhibit bainite and avoid brittle fracture. The peeling of the copper plating layer is mainly due to insufficient bonding force and low mold surface finish. The "alkaline pre-plating + acidic main plating" and diamond coating drawing die can significantly improve it. The coating holes are related to process fluctuations, nozzle slagging and cleanliness. Through real-time monitoring of key parameters, nozzle maintenance and cleanliness system control, the defect rate of holes is reduced by about 70%. This provides a systematic technical path for the development and quality control of high-performance cylinder bore thermal spray materials.