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采用热态固体颗粒介质成形工艺对金属板材筒形件成形展开研究,得到板材变形过程中的应力分布函数,并结合板材破裂失稳理论给出自由变形区冲头临界破裂成形压力的解析表达式。研究结果表明,颗粒介质所具有的主动摩擦效应和内压非均匀分布特征能显著提高板材的成形性能;冲头临界破裂成形压力随颗粒介质与板材间摩擦因数和材料塑性应变比的增加而上升,随材料硬化指数的增加而下降。各因素对冲头临界破裂成形压力影响由大到小的顺序为塑性应变比、摩擦因数和硬化指数。最后,采用AZ31B镁合金板材HGMF工艺试验对失稳理论进行验证。
The hot solid granular media forming process was used to study the forming of the metal plate and the stress distribution function during the deformation was obtained. The analytical expression of the critical breaking pressure of the free-form region was given by combining with the theory of plate rupture instability . The results show that the active friction effect and the non-uniform distribution of internal pressure of granular media can significantly improve the formability of the sheet. The critical fracture pressure of the punch increases with the increase of the friction factor and the plastic strain ratio between the granular medium and the sheet , With the material hardening index decreased. Various factors on the punch critical fracture forming pressure in descending order of plastic strain ratio, friction coefficient and hardening index. Finally, the instability theory is verified by the HGMF process test of AZ31B magnesium alloy sheet.