基于固体颗粒介质的板材软模成形工艺

选用非金属颗粒(NMG)作为研究对象，通过体积压缩试验和NMG在高应力水平下的物理性能试验，得到NMG体积压缩曲线和扩展的Drucker-Prager线性模型参数；通过摩擦强度试验，得到NMG的Mohr-Coulomb模型参数，并与扩展的Drucker-Prager线性模型参数比对基本吻合；测定了NMG与板材在不同正压力下的摩擦因数曲线。以材料性能试验为基础，对基于固体颗粒介质的板材软模成形工艺进行数值分析；设计制造固体颗粒介质板材成形试验模具，成功制出抛物线形零件。结果表明：固体颗粒介质与板材表面作用所表现出的显著摩擦性能，可以极大限度地发挥板料的成形性能；其工艺控制简便，模具结构简单；成形工件具有表面质量好、贴模性好、精度高等优点，为板材的加工和制备提供了新的方法和手段。

Flexible-die forming process with solid granule medium on sheet metal

Certain non-metallic granules (NMG) were selected as the research object. It was proposed to conduct the volume compression experiments as well as those on the NMG physical properties at high stress levels. Then, not only the volume compression ratio curve but also the extended Drucker-Prager linear model were obtained. In addition, through the friction strength tests, parameters of the Mohr-Coulomb model were gained, which proved in basic agreement with those of the extended Drucker-Prager linear model. Additionally, curves of the friction coefficients between the NMG and the sheet metal under different pressures were also obtained. Based on the material performance experiments, numerical analysis in respect of flexible-die forming process with solid granule medium (SGM) was conducted. The die and device for experiments of solid granule medium forming (SGMF) on sheet metal were designed and manufactured. Typical parabolic parts were successfully trial-produced. The tests and simulation results show that the sheet formability is significantly improved for the extraordinary friction performance during interaction between the SGM and the sheet metal surface. The process control and die structure are simple, and the shaped work-pieces enjoy many advantages, such as satisfactory surface quality and favorable die fitability, which offers a brand-new method and means for processing and preparation of sheet metals.