Papers by Author: Li Mei Ren

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Authors: W.T. Zheng, Donato Sorgente, G. Palumbo, Luigi Tricarico, Li Mei Ren, L.X. Zhou, Shi Hong Zhang
Abstract: Using the optimum blank in sheet metal forming process not only can decrease the material wasting but also avoid possible defects such as local severe thinning, wrinkling and fracture. Since it is practical technology for industrial production, many blank optimization methods have been proposed and their validity was verified by some forming tests of typical or complicated components. However, all the forming tests were carried out at room temperature or under isothermal condition. In present work, a blank optimization method was employed to evaluate its efficiency in deep drawing of rectangular magnesium alloy cups under non-isothermal condition. It is proved by experiment that the employed blank optimization method can predict successfully the optimum initial blank shape for the component with specified shape and dimension.
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Authors: G. Palumbo, Donato Sorgente, Luigi Tricarico, S.H. Zhang, W.T. Zheng, L.X. Zhou, Li Mei Ren
Abstract: In this work the superplastic behaviour of a hot rolled AZ31 magnesium alloy sheet under a biaxial tension test with the blow forming technique is presented and reported. The specimen dome height and its thickness distribution, during and after the test, have been used as characterizing parameters. A numerical FE model of the test has been developed in order to easily characterize the material and to directly analyze experimental results. The influence of the rolling cycle on the microstructure and consequently on the material behaviour has been also analyzed. A synergic use of experimental results and of the numerical model has been done for finding material constants in different situations. The material flow parameters have been found and results are presented.
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Authors: Shi Hong Zhang, Zhang Gang Li, Yong Chao Xu, Li Mei Ren, Zhong Tang Wang, Li Xin Zhou
Abstract: Press forging of magnesium alloy AZ31 sheets was investigated in this paper. The typical component, a rectangular box with bosses at the bottom was formed. The experimental results show that the magnesium alloy sheets are suitable for press forging. The bosses and the rectangular box can be formed synchronously for 2 mm or 3 mm thick sheets when the punch temperature is 250 °C. By experimentation and numerical simulation, the effects of process parameters on material flow were analyzed, including the temperature, the die shape, the blank size, the lubrication manners and the friction condition.
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Authors: Shi Hong Zhang, Li Mei Ren, Li Xin Zhou, Yong Chao Xu, G. Palumbo, L.T. Ricarico
Abstract: In the present study, warm hydroforming of cell phone cases with magnesium alloy AZ31 sheets was investigated. Fine-grained magnesium alloy sheets were prepared by cross rolling. And the tensile tests were first conducted in order to determine the proper forming temperature. The results showed that the most suitable temperature range appears to be 150-200°C. At last, the magnesium alloy cell phone cases characterized with the small round radius of all edges were formed successfully at 170°C with the low punch velocity and the maximum pressure not less than 5MPa.
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