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本文运用上限法分别分析了早期稳定流动阶段及后期非稳定流动阶段的杆杆型轴对称复合挤压过程。在密栅云纹及网格试验的基础上,提出了上述两个阶段的运动学容许速度场,并由此导出变形总功率消耗及平均相对单位压力,同时确定了变形程度和摩擦对单位压力的影响。本文还分析了早期速度场与后期速度场之间的转换关系以及挤压过程中可能出现的三种变形模式。如果正挤变形程度与反挤变形程度相差很大,则可能出现单向流动。在正、反挤压变形程度相等时,正挤部分挤出长度则可能稍大于反挤部分挤出长度。实验表明,理论结果与实验结果相当一致。
In this paper, the upper shaft method is used to analyze the rod-shaft symmetrical composite extrusion process in the early stable flow stage and the late unsteady flow stage respectively. On the basis of the dense grid moire and the grid test, the kinematic admissible velocity fields of the above two phases are proposed, and the total deformation power consumption and the average relative unit pressure are derived. Meanwhile, the deformation degree and the friction to the unit pressure Impact. The paper also analyzes the transformation relationship between the early velocity field and the late velocity field and the three deformation modes that may appear in the extrusion process. One-way flow may occur if the degree of positive and negative deformation is quite different. In the positive, anti-extrusion deformation degree equal, the positive extrusion part of the extrusion length may be slightly larger than the anti-extrusion part of the extrusion length. Experiments show that the theoretical and experimental results are quite consistent.