Common problems and solutions in the process of PE pipe extrusion

In the production process of plastic pipes, because the operators are not proficient in the process and machine operation, the plastic pipes often appear rough on the outside surface, jitter rings inside, uneven wall thickness, insufficient roundness, etc., so the process must be adjusted in time to eliminate Only when the plastic pipe production line fails can the product quality be improved.

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

Adjust the process temperature; reduce the cooling water temperature, the best cooling water temperature for PE pipes is 20～25℃; check the waterway, whether there is blockage or insufficient water pressure; check whether the heating ring of the barrel, head, etc. is damaged; adjust the water inlet of the sizing sleeve Flow rate; check the performance and batch number of the raw materials; check the mold core temperature, if it is higher than the die section temperature, lower the core temperature; clean the mold aggregates;

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

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

3. Failure of the plastic pipe production line: groove marks on the inner surface

Check whether water enters the inner tube. If water enters, pinch the tube embryo of the mold just after the exit to seal the inner cavity; reduce the internal temperature of the mold; clean and polish the mold;

4. Failure of the plastic pipe production line: a jitter ring appears inside the pipe

Adjust the water outlet of the sizing sleeve to make it even; adjust the vacuum degree of the second chamber so that the vacuum degree of the rear chamber is slightly higher than the vacuum degree of the front chamber; check whether the vacuum seal is too tight; check whether the tractor is shaking; check the main engine Whether the material is uniform;

5. Failure of plastic pipe production line: no vacuum

Check whether the water inlet of the vacuum pump is blocked, if it is blocked, unblock it; check whether the vacuum pump is working properly; check whether the vacuum pipeline is leaking; check whether the small hole in the middle of the mandrel compression screw is blocked, if it is blocked, use a thin iron wire to clear it;

6. Failure of the plastic pipe production line: the outer diameter of the pipe is out of tolerance

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

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

Adjust the nozzle angle in the vacuum setting machine and spray box to make the pipe cool evenly; check the vacuum setting machine, the water level in 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 spray box If the water temperature is more than 35℃, a chilled water system or a spray cooling box is required; check the water circuit and clean the filter; adjust the process; check and correct the inner hole diameter of the sizing sleeve; adjust the pipe guide and clamping device to correct Ovality of the pipe;

8. Failure of plastic pipe production line: uneven pipe wall thickness

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

9. Malfunction of plastic pipe production line: plasticizing temperature is too high

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

10. Malfunction of plastic pipe production line: inaccurate cutting length

Check whether the long wheel is compressed; check whether the long wheel swings, and tighten the fixing bolt of the long wheel frame; check whether the travel switch of the cutting machine is damaged; check whether the rotary encoder is damaged; whether the wiring of the rotary encoder is disconnected (aviation) Whether the plug socket is in good contact); each stand-alone enclosure (PE terminal) should be grounded to a total grounding point for reliable grounding, and the grounding point should have a grounding stake that meets the electrical grounding requirements, and each stand-alone enclosure (PE terminal) is not allowed Connect to the ground after connecting in series, otherwise it will introduce interference pulses and cause the cutting length to be inaccurate;

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

Diffusion of co-extrusion identification strips: Generally, it is caused by improper selection of co-extrusion materials used by users. Special materials such as PE should be used. If necessary, the temperature of the extrusion section can be reduced;

Co-extrusion label cannot be squeezed out: stop the main extruder, start the co-extrusion machine first, turn on the co-extrusion machine for about 10 minutes, and then turn on the host;

Co-extrusion identification strips are too thin or too wide: Generally, it is caused by the mismatch between the extrusion volume of the co-extrusion machine and the traction speed of the pipe, and should be adjusted

The frequency of the frequency converter of the co-extrusion machine or change the traction speed to match the two speeds;

The second is the reason why the cooling water jacket of the unloading section of the co-extruder is not passing through the cooling water;

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