When the twin-screw extruder is running, sometimes there may be problems of poor vacuum discharge or vacuum charging. The reasons for this phenomenon mainly include the following:
The engine temperature is low, the working pressure is large;
Material melting finger is too low, the circulation is not smooth;
The screw composition of the extruder has problems, and the pressure building before the air outlet is insufficient.
Opening too fast;
There are large quantities of substances with low melting point in the material, such as high moisture content;
The temperature setting is not standard, and the air outlet has not been plasticized;
The mesh screen is blocked more, resulting in increased engine working pressure.
For these reasons, the following solutions can be taken:
Adjust from the equipment, such as changing the vacuum port press block to a large diameter press block, or using asbestos gaskets to raise the press block here, which is conducive to gas discharge; The double discharge pipe is better than the single discharge pipe, and the overall working pressure will be more stable after the hole is increased. Adjust the extruder screw to handle the problem.
The overall temperature of extrusion can be appropriately reduced by adjusting from the processing technology, and the front section is slightly higher and the back section is slightly lower.
In actual operation, it is necessary to choose the appropriate solution according to the specific situation. At the same time, the correct operation and regular maintenance of the twin-screw extruder is also very important, which helps to reduce the occurrence of failures and ensure the smooth progress of production. For example, before starting, check the electrical wiring, water tank, feeding screw and vacuum pump rotation direction; When starting up, set the temperature control instrument parameters in each heating area according to the process requirements, start the oil pump and then start the motor, start the feeding at a low speed and make the feeding machine match the speed of the host, and start the vacuum pump after the host enters the stable operation state; In case of shutdown, it should follow the normal stopping sequence or emergency stopping operation.
