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研究了管材锥形模具机械扩径的特点,分析了扩径过程中失稳起皱的原因,建立了扩径变形区单元体力学模型,考虑材料扩径过程中的加工硬化,采用刚塑性直线硬化规律描述真实的应力-应变关系,通过主应力法推导出了锥形模机械扩径力解析公式,结果表明扩径力与摩擦系数呈近似线性增长关系,而模具半锥角在20°―30°之间存在一个使扩径力最小的最优值,并且最优值随摩擦系数的增大而增大。进一步,通过试验研究和数值模拟证明了结论的正确性。
The characteristics of mechanical expanding of pipe taper mold were studied. The reason of buckling wrinkling in expanding process was analyzed. The mechanical model of unit in expanding deformed area was established. The work hardening in the expanding process of material was considered. The law of hardening describes the true stress - strain relationship, and the analytical formula of the mechanical expanding force of the tapered die is deduced by the principal stress method. The results show that the expanding force and the friction coefficient show an approximately linear growth relationship, while the semi - 30 ° there is an optimum value to minimize the expansion force, and the optimal value increases with the increase of friction coefficient. Further, the correctness of the conclusion is proved through experimental research and numerical simulation.