This article introduced in detail the forming process, engineering logic and thinking methods of automotive dimensional engineering, discussed in depth the working object, work content, work flow, key technologies and management methods of dimensional engineering, as well as the key points of digital empowerment and transformation being carried out, the article also pointed out clearly the universal significance and practical engineering value of dimensional engineering technologies for geometric quality assurance of complex products in manufacturing industry.

Based on the frontal 25% offset collision condition, a mathematical model was established for simulation analysis. 2 000 MPa hot formed steel was used to replace 1 500 MPa hot formed steel, and the hot gas expansion method was used to replace the traditional hot forming method, thus realizing lightweight design on A-pillar structure of a vehicle model. Through the simulation analysis of small offset impact performance, it was concluded that the solution of 2 000 MPa hot formed steel meets the performance requirements. Through cost comparison and analysis, due to the reduction of the number of parts, the single vehicle cost and part mass of the overall scheme of 2 000 MPa hot gas expansion have decreased. The analysis results show that the lightweight design of A-pillar based on 2 000 MPa thermal expansion is feasible, which can reduce the cost of a single vehicle by 10.51 RMB and the weight of the designed A-pillar is 27.5% lower than the original one, which makes it have good economic benefits and lightweight effect. At the same time, the application of thermal expansion reduces the section of A-pillar cavity, reduces the obstacle angle of A-pillar by 22.2%, and effectively improves the blind area of A-pillar visual field.

With bracket parts as the main research object, this paper mainly analyzed the various kinds of failures caused by the clamping damage of bolt holes, fretting wear of bolt holes, sudden change of bracket rigidity, the manufacturing defects (burrs, microcracks) and the failures of welded brackets, emphasizing on the research on structural characteristics of parts, the morphology of crack sources for proposed improvement recommendations.

In order to solve the problem of insufficient production capacity in the welding work shop, through the analysis and research on the production line production capacity bottleneck area, 2 process optimization methods, i.e. process rebalancing and process sequence optimization, were applied to reduce the station cycle time according to the characteristics of different stations. In the implementation process, the image motion analysis method was utilized for motion decomposition of each station, to reveal the small steps of every part. At the same time, ECRS principle was used to optimize the optimization points. Finally, the cycle time optimization was successfully implemented for the 2 spot welding stations. The cycle time reduction directly improves the production capacity of the production line. There was no parameter adjustment for the optimization of spot welding process, which provided another approach to reduce the cycle time of similar station.

The welding deformation of Body In White(BIW) directly affects the performance of the vehicle and perceived quality of the interior and exterior. In order to reduce the equipment investment dueto design change, human resources and gestation cycle caused by BIW welding deformation, this paper obtains an effective and feasible process scheme by summarizing typical BIW joints such as U-, Z- and T-shaped joints, combining with welding deformation simulation, physical verification and summarization, as well as comparing different welding process of typical joints. By simulating the welding deformation of typical joints of BIW, this paper obtains the welding sequence of each joint which is most conducive to ensuring the accuracy, and proposes reference for process design, equipment selection and shortening the process design cycle.

The intermediate support is the bridge between the frame and the final assembly suspension system of a heavy truck that serves to connect the balance shaft, and keep the forces balanced between the rear axle and the middle/rear axle. This paper studied the common problems of intermediate support warpage, width and diagonal out-of-tolerance in the assembly process of the intermediate support for a heavy duty truck, analyzed the causes and developed effective solutions. By increasing the pressure type guide pin hole, repairing the wear mold, adjusting the width of the aircraft beam assembly, regulating the order of bolting at different positions, these solutions reduced the unqualified rate and production cost of the intermediate support assembly, improved the overall quality and production efficiency of the heavy duty truck frame.

This article introduced corner cracking of A-pillar hot-stamped part of a vehicle model. Simulation analysis reveals no cracking crisis in stamped part, whereas parts crack in actual industrialization. Cracking mainly incurs at the convex corner with long flange surface. The cause of cracking was analyzed by comparing forming status of parts at cracking position and stamping simulation & analysis parameters, the factors leading to corner cracking of hot-stamped parts were summarized, and simulation & analysis strategy of such parts in stamping was also summarized, the solution of corner cracking was introduced both in product and process perspectives.

With the vacuum formed and coated instrument panel of a vehicle as the research object, this article, through experimental analysis, indicated that the instrument panel blistered, and triggered the blistering condition after the vehicle was exposed to a high temperature of more than 100 ℃ for 30 minutes continuously. The research focused on enhancing the bonding strength of glue and skeleton as countermeasure. Through research, the bonding strength can be enhanced by adjusting the mold gap, enhancing the exhaust property of the skeleton, and increasing the roughness of the skeleton, so as to eliminate blistering. The article also pointed out that adding the oven with temperature of 100 ℃ for 30 min as a quality control procedure can effectively prevent the blistering and defective products from flowing out of the production line, and provide a reference for solving the problem of blistering in the vacuum forming coating process.

In order to effectively control the influencing factors in the process of laser brazing, ensure the stability of quality and efficiency in the welding process, this article, taking the laser brazing of the top cover of a vehicle model as an example, analyzed the factors affecting the stability of the laser brazing process from 2 aspects of laser brazing system, body precision and matching control system through the experience accumulation of optimization verification and problem handling in the process and related application practices in the industry. At the same time, the control measures of the associated system were formulated and the control requirements were formed, to promote the stability of the laser brazing application process and ensure the product quality and production efficiency.

Graphite composite bipolar plate was prepared by tape casting method. With electrical conductivity and mechanical properties as the main indexes, combined with Scanning Electron Microscopy (SEM) characterization technology, the slurry viscosity, slurry temperature, tape casting speed, scraper height and liquid level height were explored to study the tape casting process of the green billet of bipolar plate. The results show that, the suitable slurry viscosity is 5 500~6 500 mPa·s, the slurry temperature is 35~40 ℃, the slurry velocity is 0.5~0.6 m/min, the scraper roll height is 1.2~1.4 mm, and the liquid level height is 2.5~3.5 cm. In this case, the fluidized plate has high density of embryos, uniform adhesion, smooth surface and high smoothness.

The new thin Al-Si coating hot-formed steel has some advantages in automobile application, such as improving the properties of bending angle and so on with the tensile strength, yield strength and elongation rate remain unchanged. This article studied the application properties of 1 500 MPa hot-formed steel with thin Al-Si coating, including formability, welding property, corrosion property and adhesive property. The results show that the thin Al-Si coating has no effect on the formability, it improves the welding performance, while the corrosion resistance degrades slightly, however the overall performance meets design specification, and the adhesive property has no obvious change. Therefore, the batch application of hot formed steel with thin Al-Si coating on car body can be promoted.

According to SEP1220-2 Standards, the resistance spot welding current process window of hot-dip galvanized DH600 steel plate with high formability was determined, and its welding process performance was comprehensively evaluated in combination with shear tensile test, cross tensile test, metallographic test, micro-hardness test and electrode life test. The results show that the new material shows better welding performance than traditional DP590. In the welding process window, with the increase of welding current, the nugget diameter increases, and the joint strength also increases. The microstructure of the weld nugget is lath Martensite, and no softening phenomenon is detected in heat affected zone. The electrode life test shows that the new material has good electrode wear resistance.

In this paper, the flexible and efficient warehouse with combination of Rail Guided Vehicle (RGV) and lift was the research object. In order to solve the problem that the traditional high speed stacker spatial warehouse cannot meet the high beat capacity Jobs Per Hour (JPH) of 60 Units/h, this spatial warehouse adopted RGV conveying in the horizontal plane and lift conveying in the vertical direction. CAD software was utilized to plan and design the two-dimensional plan of the spatial warehouse, Catia software was adepted to design the three-dimensional model of the corresponding three-dimensional warehouse, and Plant Simulation software was used to verify whether the solution can meet the high beat capacity, and the economic investment was compared with that of the traditional stacker three-dimensional warehouse through cost calculation. The final conclusion is that this flexible and efficient three-dimensional warehouse can meet the JPH 60 Units/h beat capacity and the economic cost is lower than the traditional three-dimensional warehouse, which has wide application prospect.