Extruder screw role is to make the glue with the screw rotation movement gradually into a straight line, the direction of the nose, and with the fuselage, compressed raw heat, softening stirring, mixing glue.
The screw is made up of threads and cylinders. The screw rod has a long hole along the centerline, and can pass the cooling water. The tail of the screw is mounted in the thrust bearing and avoids the reacting force when the rubber is extruded.
The diameter of the screw is slightly smaller than the inner diameter of the fuselage, i.e. the diameter of the screw and the inner surface of the steel sleeve shall have clearance, and the clearance is generally controlled in 0.002~0.004 times of the screw diameter. The clearance is too small to cause the screw "sweep the bore", produce wear, even the phenomenon of the dead screw rod; the clearance is too large to affect the extrusion volume, low production efficiency, but also affect the product quality.
Screw Thread Properties
The thread depth is directly related to the equipment production capacity, the thread depth is large, under certain pressure, the extruded rubber material is more. But the plastic material is difficult, the screw strength is also poor. Screw thread depth is generally controlled in 0.18~0.25 times of screw diameter. The thrust surface of the thread should be perpendicular to the axis of the screw, and the relative surface of the propulsion surface should have a certain inclination. The axial distance of adjacent threads is called pitch, and the screw of the rubber extruder is generally equidistant and unequal with double-headed screw threads.