中文摘要：

摩擦是金属成形中一个关键影响因素，它产生于存在相对运动的金属和模具接触面上。恶劣的摩擦条件将阻碍金属的流动，使成形载荷显著增加，成形能耗增加。因此，采用合适的途径来改善金属成形中的摩擦条件，对于降低成形力，促进金属流动，增加工件的成形质量和精度、提高模具的使用寿命等方面都具有明显的实际应用价值。目前，有限元数值模拟技术已经成为预测金属流动、成形载荷和模具受力的重要手段，因此，金属成形计算中的摩擦作为重要的边界条件获得了广泛的重视及深入的研究。在对不同摩擦试验方法研究的基础上，可知摩擦因子及因数随着材料新表面生成率、接触压强的增加而增大。对改善摩擦条件的金属表面处理方法、包套挤压、振动辅助成形等考虑摩擦的省力成形途径进行简要介绍。

英文摘要：

The friction is a key factor in metal forming, it comes into being with the existence of the contact surface between metal and die which have relative motion. The severe friction conditions will inhibit the flow of metal, increase the forming load significantly and increase the forming energy consumption. Therefore, it has an obvious practical application value of finding a suitable friction conditions in metal forming to reduce the forming load, promoting the metal flow, increasing the forming precision and quality of the workpiece, and improving the die life. Currently, the finite element numerical simulation technology has been used as an important method to analyze the metal flow, the forming load and the die force. The friction criterion and its parameters, as one of the important boundary condition, have got extensive attention and been deeply investigated. The friction factor and coefficient increase with the increasing of new surface generation rate and contact pressure, on the basis of studying the different friction experiment methods. The approaches to realize less-loading is briefly introduced including metal surface treatment for improving friction conditions, sheath extrusion, vibration auxiliary forming.