PVC-U异型材高速挤出中螺杆“扫膛”的原因及预防措施

Reasons for "barrel scratching" of screw in the high-speed extrusion of PVC-U profiles and the preventive measures

分析了PVC-U异型材高速挤出时平行异向外旋双螺杆“扫膛”的原因是螺杆长径比过大和螺杆受到的分离力产生的力矩作用,采取的预防措施是在螺杆扭矩及螺杆充满长度允许的情况下,尽量提高螺杆物料充满度,可以降低螺杆所受到的力矩,减小螺杆变形,从而有效地预防螺杆“扫膛”现象的发生。

Reasons for the ＂barrel scratching＂ of outward rotating double parallel screw in the high- speed extrusion of PVC- U profiles were analyzed, which were caused by the large lengthdiameter ratio and the moment caused by the separation stress on screw. The adopted preventive measures were as follows： within the permission of torsional moment and full - filled length of screw, increasing the filled ratio of materials in screw as large as possible. So the moment of force on screw could be reduced and the deformation of screw could be decreased ,and thus the ＂barrel scratching＂ of screw could be prevented effectively.