粉末冶金盘式汽车摩擦片热压成形的数值模拟与实验研究

Numerical and experimental study on hot press of powder metallurgical disk brake pad

为了探明汽车盘式摩擦片剪切强度不稳定的原因,用数值方法模拟摩擦片热压成形过程中温度分布和模具局部失效对粉末流动和固结的影响,并进行了相应的实验分析和验证。结果表明:模具局部失效及温度梯度分布造成基体材料溢出,基体材料的流动导致在剪切面上纤维集合定向排列,从而大幅度降低试样的剪切强度;当基体出现剪切层,导致纤维成定向分布时,剪切强度明显下降,低于要求的014MPa(最高值仅为01356MPa),而在无溢出情况下,剪切强度都高于014MPa。

To find out the causes about unstable shear strength of PM disk break pad, the hot press process of PM disk brake pad was numerically simulated by using finite element method. The influence of temperature distribution and mould failure on powder flow and consolidation was analyzed, and the corresponding experiments were conducted. The effect of powder flow on fiber orientation and shear strength was unveiled. The results show that mould failure and temperature gradient can lead to obvious flow of matrix in the shear direction. The flowing of matrix can result in oriented arrangement of fiber in shear direction and greatly reduce the shear strength of samples. In the situation of fiber orientation caused by shear layer, the pads' shear strength can only reach 0.356MPa; while in normal condition it can attain to 0.4MPa or higher.