Common problems and solutions in PE pipe extrusion process

2022-06-17

In the process of plastic pipe production line, because the operator is not skilled in the process and machine operation, it often causes the plastic pipe to have a rough outer surface, a jitter ring inside, uneven wall thickness, and insufficient roundness. Therefore, it is necessary to adjust the process in time to eliminate The failure of the plastic pipe production line can improve the product quality.



1. Plastic pipe production line failure: the outer surface of the plastic pipe is rough

Adjust the process temperature; reduce the cooling water temperature, the best cooling water temperature for the PE pipe is 20-25 °C; check the water channel for blockage or insufficient water pressure; check whether the heating ring such as the barrel and the head is damaged; adjust the water inlet of the sizing sleeve flow; check the performance and batch number of the raw materials; check the temperature of the core of the mold, if it is higher than the temperature of the die section, lower the temperature of the core; clean the aggregate of the mold;

2. Failure of the plastic pipe production line: groove marks appear on the outer surface of the plastic pipe

Adjust the water pressure of the sizing sleeve, and the water output should be balanced; adjust the angle of the nozzle in the vacuum setting box to make the pipe cool evenly; check whether there are sundries, burrs, etc. in the die, sizing sleeve, cutting machine and other hardware;

3. Plastic pipe production line failure: groove marks appear on the inner surface

Check whether the inner tube has entered the water. If the water enters, squeeze the tube blank that has just exited the mold to seal the inner cavity; reduce the internal temperature of the mold; clean and polish the mold;

4. Plastic pipe production line failure: jitter ring appears inside the pipe

Adjust the water outlet of the sizing sleeve to make the water outlet uniform; adjust the vacuum degree of the second chamber so that the vacuum degree of the rear chamber is slightly higher than that of the front chamber; check whether the vacuum gasket is too tight; check whether the tractor has jitter; Whether the material is uniform;

5. Plastic pipe production line failure: no vacuum

Check whether the water inlet of the vacuum pump is blocked, if it is blocked, clear it; check whether the vacuum pump works normally; check whether the vacuum pipeline is leaking;

6. Plastic pipe production line failure: the outer diameter of the pipe is out of tolerance

Adjust the size of vacuum to change the size of the outer circle; adjust the traction speed to change the size of the outer circle; correct the size of the inner hole of the sizing sleeve;

7. Failure of the plastic pipe production line: the roundness of the pipe is out of tolerance

Adjust the angle of the nozzles in the vacuum setting machine and the spray box to cool the pipes evenly; check the water level in the vacuum setting machine and the spray box, and the pressure of the water pressure gauge to make the spray volume large and powerful; check the vacuum setting machine and the spray box If the water temperature is higher than 35°C, it is necessary to configure a chilled water system or add a spray cooling box; check the water circuit, clean the filter; adjust the process; check and correct the inner hole circularity of the sizing sleeve; The ovality of the pipe;

8. Plastic pipe production line failure: uneven wall thickness of the pipe

Adjust the wall thickness on the mold; adjust the angle of the nozzles in the vacuum setting machine and the spray box to make the pipe cool evenly; adjust the water outlet of the sizing sleeve to make the water outlet evenly; disassemble the mold, check whether the screws inside the mold are loose, and re-tighten them;

9. Plastic pipe production line failure: plasticizing temperature is too high

Adjust the process; adjust the heating temperature of the mold core, and ventilate and cool the inside of the mold; the shear heat of the screw is too high, replace the screw;

10. Plastic pipe production line failure: inaccurate cutting length

Check whether the length-measuring wheel is pressed tightly; check whether the length-measuring wheel swings, and tighten the fixing bolts of the length-measuring wheel frame; check whether the travel switch of the cutting machine is damaged; check whether the rotary encoder is damaged; Whether the plug socket is in good contact); each stand-alone shell (PE terminal) should lead the grounding wire to a general grounding point for reliable grounding, and the grounding point should have a grounding stake that meets the electrical grounding requirements, and each stand-alone shell (PE terminal) is not allowed. Connect to ground after connecting in series, otherwise interference pulses will be introduced, resulting in inaccurate cutting length;

11. Failure of plastic pipe production line: problem of co-extrusion marking strip

Diffusion of co-extrusion marking strips: generally caused by improper selection of co-extrusion materials used by users, special materials such as PE should be used, and the temperature of the extrusion section can be lowered if necessary;

If the co-extrusion logo strip cannot be extruded: stop the main extruder, turn on the co-extruder first, turn on the co-extruder for about 10 minutes, and then turn on the main machine;

The co-extrusion marking strip is too thin or too wide: generally due to the mismatch between the extrusion volume of the co-extruder and the pulling speed of the pipe, it should be adjusted

The frequency of the frequency converter of the co-extruder or the pulling speed can be changed so that the two speeds can be matched;

The second is the reason why the cooling water jacket of the co-extrusion machine does not pass through the cooling water;

There will be other abnormal situations in the actual production process of the pipe production line, which should be dealt with according to the actual situation.





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