The screw of the twin-screw extruder adopts a modular design, which consists of a shaft and an extruder screw module. The extruder screw is mainly composed of a transport module and a pre-plastic module.
1. Seals.
As one of the extruder screw components of the extruder screw, it transports and prevents the raw material from being discharged from the extruder screw.
2. Main feeder.
Large pitch and force-transmitting extruder screw elements ensure that the raw material is transferred to another melting zone. Large interval, medium interval, and small interval ensure the rapid transportation of raw materials, and then ease the shrinkage of raw materials and filling extruder screws to prepare for compounding.
3. Premolding a part (melting and mixing).
Initial mixing is done by premolding different combinations of elements.
Pyrogen: 10%-20% comes from heating inside the barrel, 80%-90% comes from raw material cutting and friction.
Composite materials: suitable for mixing several types of polymer resins or fillers. It is best to add fillers or liquids after the polymer is melted.
4. Let it out naturally.
Extruder screw design scheme: large pitch drive system components. Left-handed helical elements need to be used in front of the gas outlet to bring about the return of raw materials and create high pressure to remove volatile impurities as well as vapors and vapours.
5. The feeding part of the side feeder.
Purpose: To add suitable raw materials to molten polymer.
Extruder screw design: transport components with large spacing for empty stomach transport. And use small-pitch components to shrink the raw material before the side-feed feeder.
Raw materials: glass fiber, carbon fiber or filler materials are generally added.
Temperature: The side feeder or the next barrel section may be below the settling temperature. The heater needs to keep working.
6. Part of premolding (mixing)
7. Vacuum outlet.
Purpose: Use a pump to remove volatile impurities, gases and vapors from molten raw materials.
Extruder screw design scheme: large pitch drive system components. A left-handed helical element needs to be used before the air outlet to generate material backflow and generate high pressure.
Device: connected to the water ring pump through the pipeline.
Temperature control: During the endothermic process, the temperature may be lower than that of the precipitation due to gas absorption.
Quality: If the vacuum is not enough, the particles will foam or contain gas. And it can also cause raw material to flow back into the feeder and side feeder to create stacks.
8. Pressure measurement part.
Pressurize and extrude raw materials