The Correct Disassembly Method for Twin-screw Extruder Screws

The screw of the parallel twin screw extruder in the same direction is designed based on the principle of integration, and can be replaced and combined according to different material needs. When disassembling the screw, the material inside the main machine should be drained as much as possible (if the material is high viscosity plastic such as PC or medium viscosity plastic such as ABS and POM, PP or PE material can be added to clean the chamber before parking). Then, the main machine and various auxiliary machines should be stopped, and each section of the electric heater can still maintain normal operation. Then, the screw should be replaced according to the following steps.

 

1. Remove the pressure and temperature measuring components, remove 8 M16 screws, wear asbestos gloves, rotate the machine head and mesh replacement components to the side, and clean the material at the end of the machine head ∞ hole and the end of the machine head screw while it is hot. Caution: To prevent burns.

2. Remove and tighten the nut (left-hand thread), and replace it with a screw removal tool.

3. Loosen the set screws of the two couplings near the screw shaft ends, and observe and remember the corresponding letter marks of the spline at the tail of the two screws and the sleeve coupling.

4. Slowly pull out the two screws synchronously. Use a wire brush or copper shovel to quickly clean the surface material of the screws while they are hot. Apply an appropriate amount of paraffin on the surface of the screws, and use a cotton cloth to wipe the surface of the screws for good results. After cleaning all the screws, pull them out and place them flat on a wooden board or two sleepers.

5. Remove the screw removal tool (left-hand thread) from the screw, and disassemble the screw components while they are hot. Sharp quenching tools are not allowed to be used to strike them. A wooden hammer, copper rod, or aluminum rod can be used to gently strike around the screw components. Avoid hitting the thin wall of the threaded block end face. If there is material seeping into the surface of the core shaft, which makes disassembly difficult, it can be re placed in the cylinder for heating. After the material in the gap softens, it can generally be removed while it is hot.

6. The end face, inner hole, and keyway of the removed extruder screw components should be cleaned in a timely manner. Arrange neatly on the shelf. It is strictly prohibited to collide with each other (anti rust grease should be applied to screw components that are not in use temporarily). The surface of the core shaft should also be thoroughly cleaned of residual materials. If not assembled temporarily, it should be vertically suspended to prevent deformation and coated with anti rust grease.

7. The holes inside the extruder barrel can be cleaned with a wooden stick wrapped in a cloth roll.

8. The assembly configuration of the two twin-screw screws must be completely identical. During assembly, the inner holes of each component and the surface of the core shaft must be evenly coated with a thin layer of high-temperature resistant lubricating grease. When installing each screw component on the core shaft, its end face must be cleaned thoroughly, and finally the compression screw must be tightened.

9. After placing the two screws side by side in the working position at a 90 ° phase, slowly insert them into the barrel. After the position of the spline at the tail end of the screw corresponds to the sleeve coupling, both screws are pushed in at the same time, so that the tail end of the screw is tightly fitted with the output shaft end face of the transmission box. Before installing the screw, a thin and uniform layer of lubricating grease can be applied to the spline at the tail end.

After the screw is installed, it should be manually turned to rotate the screw for more than two cycles. After confirming that there is no interference, scraping, or other abnormal phenomena, the screen replacement and machine head components can be installed. During installation, the thread surfaces of each screw should be evenly coated with high-temperature resistant lubricating grease.

After heating the barrel and head of the twin-screw extruder to the set temperature and stabilizing it, it can be started according to the normal program.

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