Hot stamping of aluminum alloy is an important manufacturing method to achieve the goal of automobile lightweight,and scrat-ches and cracks of sheets caused by friction and wear in the production process are the main obstacles to mass production.In order to study the applicability and lubrication mechanism of lubricants in hot stamping process,based on the pin-disk friction experimental equip-ment,the experimental conditions of hot stamping were studied by reasonable experimental design,and a water-based release agent with similar working condition was selected for friction experiment to evaluate its lubrication performance under the hot stamping condition and explore its lubrication mechanism.Furthermore,through experiments,it is found that the water-based siloxane lubricant could obtain a long time low friction factor state by isolating the die from the workpiece.So it is feasible to use water-based lubricant to achieve stable and low friction factor state in hot stamping process of aluminum alloy.
Abstract. In this paper, the forming process research of the front opening and closing mechanism hatch for multiple units was carried out, and the industrial grade 5083 aluminum alloy was selected as the original material. The uniform rapid superplastic forming process combined with hot stamping and direct-reverse superplastic forming was used to form the hatch body skin, the cold stamping and argon arc welding process were used to produce the connection support, and the hatch integral part was obtained by argon arc welding finally, which solved the problem of poor environmental protection and high ratio of traditional FRP hatch and high precision forming of the large complex thin-walled structural part that cannot be achieved by the traditional forming process. After process research and development, finite element analysis, and forming tests, the aluminum alloy hatch with good forming quality was successfully manufactured. The ultimate thinning rate of the part was 23.8%, the overall wall thickness was evenly distributed, the deviation of shape was controlled within 1 mm, and the mechanical properties met the relevant technical requirements.
The room temperature forming ability of 5A06 aluminum alloy is limited,and it is prone to cracking in stamping,for this prob-lem,the warm forming of 5A06 aluminum alloy sheet was researched,and based on the M-K groove theory,the formability of 5A06 alu-minum alloy sheet was predicted.Firstly,a constitutive model of 5A06 aluminum alloy under the conditions of 200-300℃and 0.01-1 s-1 was established by combining theoretical calculation and experiment.Then,the Swift material strengthening model was introduced into the derivation of forming limit,the forming limit diagram and the initial thickness unevenness predicted by the M-K groove theory were obtained by the Newton-Raphson iteration method.Finally,the Nakajima test was conducted on the 5A06 aluminum alloy sheet to verify the accuracy of theoretical prediction results.The results show that the M-K groove theory can effectively predict the formability of 5A06 aluminum alloy within the experimental temperature range.
For the riveting forming of two layers of 5052 aluminum alloy sheets with the thickness of 1.5 mm in the battery pack of new energy vehicles,a new structural rivet was designed based on the waterproof requirement after riveting of sheets.Then,the sheet metal riveting forming process was simulated based on finite element software DEFORM-2D,and the simulation results were verified by installing the die and riveting equipment.The simulation results show that the simulation values of head penetration,residual thickness,interlocking length between rivet and upper plate,and interlocking length between lower plate and upper plate are 0.038,0.210,0.526 and 0.505 mm respectively.The relative errors between numerical simulation and experimental values are 7.89%,7.14%,6.08%and 12.67%respectively.Therefore,the reliability of DEFORM simulation applied to the riveting is verified by experiments.In addition,through simulation analysis it is known that the interlock length increases with the increasing of riveting speed and die installation width,while it decreases with the increasing of die installation depth.
In order to solve the lubrication problems in vacuum isothermal forging,for two glass lubricants RD-1 and GR-2,the wetting angle was measured by the seat drop method,the linear expansion coefficient was measured by the differential method,the high-tempera-ture viscosity was measured by the rotation method,and the combination of coating and substrate was observed by the trial firing method combined with scanning electron microscopy.Then,vacuum isothermal compression tests were conducted under different process condi-tions to explore the relationship between friction factor and process parameters.The experimental results show that RD-1 glass lubricant has better wettability property and lower high-temperature viscosity in the vacuum isothermal forging.The linear expansion coefficients of the two glass lubricants are similar,and the thicknesses of the interface coating are both 40-50 μm.In the forging temperature range of 950-1000℃,the friction factor of RD-1 glass lubricant is lower,which shows better lubrication performance and is more suitable for the vacuum isothermal forging process below 1000℃.
