The screw is made of threads and cylinders. The screw has a long hole along the centerline and can pass through the cooling water. The tail of the screw is mounted in the thrust bearing to avoid the reaction of the screw when the screw is pushed.
The diameter of the screw is slightly smaller than the inner diameter of the steel casing of the fuselage, that is, the diameter of the screw is spaced from the inner surface of the steel sleeve, and the gap is generally controlled at 0.002 to 0.004 times the screw diameter. The gap is too small will cause the screw "sweep chamber", resulting in wear and tear, and even produce the phenomenon of stuck screw; gap too much rubber material impact of the amount of extrusion, low production efficiency, but also affect product quality.
Screw thread characteristics
Thread depth and equipment production capacity is directly related to the depth of the thread, under a certain pressure, extrusion more than rubber. But the plastic material is difficult, the screw strength is also poor. Screw thread depth is generally controlled at 0.18 to 0.25 times the screw diameter. The advancing surface of the thread should be perpendicular to the axis of the screw, and the opposite face of the thrust surface should have a certain slope. The axial distance of the adjacent threads is called the pitch, and the rubber extruder screws are generally equidistant, deep and double-headed screw.
Next: Causes Of Screw Wear