塑料挤出模具设计的分析

The Analysis of Plastics Extrusion Die Designing

围绕塑料挤出模具设计中应注重的熔料的流速特性和 Barus效应 ,分析了熔料在光滑圆形孔中、矩形孔内、矩形流道内壁不平行且呈棱锥体等几种不同几何形状中的流动情况 ,以及 Barus效应对熔料离开挤出模模口的塑料型坯尺寸和塑料熔体型坯几何形状的影响 .研究证明 :凡是熔料流经的模腔几何形状必须呈光滑流线型面 ,为减小 Barus影响 ,挤出模成型部分的长度 。

Focus on the flow velocity character and Barus effect of melting plastics which should be emphasized on designing the plastics extrusion die, this paper analyses the melting plastics in three flowing conditions, such as in circular bore, in rectangular bore, and in rectangular bore with unparalleled inner surface which takes the form of pyramid. Further more, deals with the affection of Barus effect to the dimension and geometric shape of plastic melting mould base which is leaning from the moulding entrance. In order to make sure of the accuracy and property of the extrusion moulding part, the geometric shape of the die cavity, through which the melting plastics will flow, should be designed to be smooth flow lined surface when designing the extrusion die for plastics.To reduce the affection of Barus effect, the length of the farming parts of extrusion die should be decided according to the flow changing property of different plastics.