粉末成形过程中摩擦行为研究进展

Research Progress of Friction Behavior during Powder Forming

粉末成形过程中的摩擦行为是一个十分复杂的问题,受粉末和模具材料性能、粉末形状大小、模具表面状况、粉末与模具间相对运动速度、润滑剂特性、粉末和模具温度等许多因素的影响。摩擦造成了制品密度低、分布不均匀、模具磨损,影响了制品的性能、尺寸精度及其应用范围。特别是复杂形状、厚度尺寸较大的粉末冶金制品,摩擦的存在极易造成制品的失效。摩擦行为的复杂性使得对其进行准确的测定和表达比较困难,加之这方面的研究不多,造成了进一步研究的困难。综述近几年国外对粉末成形过程摩擦现象的研究进展,着重介绍目前常用的两种摩擦测试和描述方法,即闭模式和剪切板式摩擦测定方法,为进一步研究粉末成形中的摩擦行为、提高制品性能提供参考。

The friction behavior is a very complicated problem during powder forming. There are many factors affecting the friction behavior, which include properties of powder and dies, morphology and size of powder, surface condition of dies, relative velocity between dies and powder, properties of lubricant, temperature of die and powder, and so on. The existence of friction causes low density, uneven density distribution, and die wear, thereby affecting the performance, dimension precision and application range of powder metallurgy products. Friction will easily cause the failure of PM parts, especially those with complex shape and large thickness and dimension. The complication of friction behavior makes it difficult to be accurately measured and expressed, and the researches on it are not many, so it is difficult to make further research. Foreign research progresses of friction behavior in powder forming process are summarized, and two common methods of measurement and expression of friction are introduced, namely instrumented dies method and shear plate method. This will offer reference for further research of friction behavior in powder forming and for improving the performance of PM parts.