影响挤出膨胀因数和收缩率的工艺及设备因素

Effect of technology and equipment on die swell and shrinkage during extrusion

阐明影响挤出胎面膨胀和收缩的主要工艺及设备因素是口型板的结构和尺寸、挤出条件以及设备。口型的冠部截面大、口型圆角R小、流胶口大 ,排胶温度高 ,挤出速度慢 ,则膨胀因数小 ;反之 ,膨胀因数大。冷却效果好 ,胎面稳定性高 ,收缩率小。认为 :要减小胎面变形 ,口型总宽度应大于半成品总宽度 ,差值为 30～ 50mm ;冠宽略小于半成品冠宽 ,差值为 3～ 10mm ;口型圆角R取值以 2～

The effect of the technology and equipment,such as the structure and dimension of die plates,the extrusion conditions and so on, on the die swell and shrinkage of tread extrudate was described.The swell factor tends to decrease if the cross section of die crown is large,the die round R is small,the runner is large,the dumping temperature is high and the extrusion speed is low;otherwise the swell factor tends to increase.The high stability and small shrinkage can be obtained if the tread extrudate is sufficiently cooled.It is found that the total width of die should be 30～50 mm greater than that of semi product,the width of die crown should be 3～10 mm less than that of semi product,and the die round should be 2～3 mm to decrease the deformation of tread extrudate.