To solve the abnormal discharge of the twin-screw extruder, it is necessary to understand the working principle of the twin-screw extruder.
The twin-screw extruder is one of the multi-screw extruders. It is developed on the basis of a single-screw extruder. In the barrel of the twin-screw extruder, two screws are placed side by side. Twin screw extruder. According to the relative position of the screw, it can be divided into meshing type and non-intermeshing type. The meshing type can be divided into partial meshing type and full meshing type. According to the direction of rotation of the screw, it can be divided into two types: the same direction rotation and the reverse rotation type. It can be divided into inward and outward. The nature of the co-rotating twin-screw pressure zone is different, and the material is rotated by the screw in the inner cavity of the sleeve to generate a high pressure zone and a low pressure zone.
Second, so the twin-screw extruder extrusion is not normal may be the following:
1. When the time is large, the feed is not smooth. If the solid raw material melts prematurely, it will stick to the screw, resulting in poor feeding or even material loss. This is the screw ring knot phenomenon that is usually said. Once the ring knot is generated, The most thorough solution is to pull out the screw and clean the glue at the feed end (the adhesive at the extrusion end does not matter).
2. The temperature of the screw feed section is too high, which will cause ringing problems. If the screw has cooling water, the flow rate of the cooling water is too low, which may cause ringing problems. In addition, the screw needs to reach a certain speed to achieve a stable extrusion pressure, because there is a gap between the screw and the sleeve, and the rotation speed is too low, which may cause the molten material to flow back from the gap, causing ringing or extrusion pressure fluctuation.
3, different raw materials, softening point and melting point are different, the process requirements are different (mainly different temperatures)
4. The degree of wear of the twin-screw extruder barrel and the screw. If the barrel and the screw have a large wear, it will cause uneven discharge or fail to meet the specifications of the normal use.