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摘要：
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<正> 复合挤压在冷挤压生产中得到广泛应用,例如工具五金中的套筒头、汽车拖拉机中的活塞肖等等,都是应用复合挤压流动成形制成。在生产实践中,通过实测可得不同变形程度下的复合挤压力。在复合挤压无截流时,由一定的正挤变形程度和一定的反挤变形程度组成的复合挤压,其挤压力比单纯正挤压和单纯反挤压要低,或等于二者中较小的力。目前国内、外对单纯正挤压和单纯反挤压,获得了许多可供实际应用的数据,同时从理论
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Limit analysis is the effective and Convenicnt method for determining the extrusion force, the degree, of deformation and the Various parameters of the forming processes. In this paper, the analyses for the Problem of Combined extrusion of axial symmetry have been made by the principles of the upper bound. The slip line field of the combined exfrusion is drawn from that of forward and backward extrusion, then a zero blow-rate point is obtained. It can be considered as the boundary between the rigid region and the plastic region, the model of the metal flow for the combined extrusion can be designed according the rigions divided. Below it,the problem can de considered as one of axial symmetry,and above it, the problem can be considered as one of plane deformation. The velocity fields are drawn for each case, and the power needed for the forming process is calculated. Finally, the numerical value of the upper bound of extrusion force is obtained. The hardening effect of materials extrusion force has been especially considered. The true stress-strain curve is experimentally determined. The true stress values are introduced for different degrees of deformation for calculation, the comparison of theoretical values with experimental values is made,only 3.6% error exists,
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基金项目：
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作者简介：
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参考文献：
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[1] Avitzur B. Metal Forming Processes and Analysis 1978．
[2] Erich G Thomsen 等 Mechanics of Plastic Deformation in Me tal Processing 1965．
[3] #12
[4] #12
[5] 清华大学锻压教研室 锻压工步的力学分析
[6] 赵静远 金属复合挤压变形规律的研究锻压技术1980 No.1
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