高密度聚乙烯注射模点浇口大小的研究

Study of Point Gate Dimention for HDPE Injection Mold

采用浇口可更换的阿基米德螺旋线模具，研究了ＨＤＰＥ（５０００Ｓ）螺旋线流动长度和浇口直径的关系，对影响螺旋线流动长度的因素（粘度、温升和压力降）与浇口大小的关系也作了研究，结果表明，浇口直径增大３倍，粘度增加２３倍，而压力降和温升都减少了１２倍，浇口处熔体粘度的下降，主要是由于剪切速率增加，而温升对粘度下降的贡献很小。因而建议对ＨＤＰＥ（５０００Ｓ）而言，浇口直径为１．０～１．２ｍｍ，在该范围内变动对模腔的充填影响很小。

s By using Achimedean spiral mold with changable gate,the relation of gate diameter with spiral lengths of HDPE(5000S) was studied.The relation of viscosity,temperature raise and pressure drop,which had effects on spiral lengths,with gate diameter was also studied.The results showed when the gate diameter increased by 3 times,the viscosity increased 23 times,but the pressure and temperature all decreased 12 times.The decrease of gate diameter was mainly due to the increase of shear rate.The increase of temperature had little effect on the decrease of viscosity. Therefore,the gate diameter for HDPE(500s) would better to be 1.0～1.2mm,and changes within the above mentioned diameters had little effect on the filling of the mold.