Common troubles and solutions of polyolefin pipe extrusion production

In the process of plastic pipe production line, because the operators are not proficient in the process and machine operation, they often lead to rough outer surface, shaking ring, uneven wall thickness and insufficient roundness of plastic pipe. Therefore, it is necessary to timely adjust the process and eliminate the production line fault of plastic pipe to improve the product quality.

1. Rough outer surface of plastic pipe

Adjust the process temperature; reduce the cooling water temperature. The preferred cooling water temperature of PE pipe is 20-25 ℃; check the water circuit for blockage or insufficient water pressure; check whether the heating rings such as the barrel and the head are damaged; adjust the inlet flow of the sizing sleeve; check the performance and batch number of raw materials; check the core temperature of the mold. If it is higher than the temperature of the die section, lower the core temperature; clean the mold assembly Material;

2. Groove mark on the outer surface of plastic pipe

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

3. Groove mark on inner surface

Check whether there is water in the inner tube. If there is water in the inner tube, the tube embryo of the die with rigid outlet shall be pinched firmly to make its inner cavity closed; the internal temperature of the die shall be reduced; the die shall be cleaned and polished;

4. Jitter ring 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 to make the vacuum degree of the rear chamber slightly higher than that of the front chamber; check whether the vacuum gasket is too tight; check whether there is shaking phenomenon in the tractor; check whether the discharge of the main engine is uniform;

5. No vacuum

Check whether the water inlet of the vacuum pump is blocked, if so, dredge it; check whether the vacuum pump works normally; check whether the vacuum pipeline leaks; check whether the small hole in the middle of the core molding screw is blocked, if so, dredge it with fine wire;

6. Out of tolerance of pipe outer circle size

The external dimension can be changed by adjusting the vacuum degree; the external dimension can be changed by adjusting the traction speed; the internal hole dimension of the sizing sleeve can be modified;

7. Pipe roundness out of tolerance

Adjust the nozzle angle of the vacuum setting machine and spray box to make the pipe cool evenly; check the water level and pressure of the water pressure gauge in the vacuum setting machine and spray box to make the spray volume large and powerful; check the water temperature of the vacuum setting machine and spray box. If it is more than 35 ℃, it is necessary to configure the freezing water system or add the spray cooling box; check the water path and clean the filter; adjust the process; check and correct Adjust the pipe guide clamping device to correct the ovality of the pipe;

8. Uneven pipe wall thickness

Adjust the wall thickness on the mold; adjust the angle of the nozzle in the vacuum setting machine and spray box to make the pipe cool evenly; adjust the water outlet of the sizing sleeve to make it even; disassemble the mold, check whether the screw inside the mold is loose, and tighten it again;

9. Too high plasticizing temperature

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

10. Inaccurate cutting length

Check whether the long wheel is tightly pressed; check whether the long wheel swings, and tighten the fixed bolts of the long wheel frame; check whether the travel switch of the cutter is damaged; check whether the rotary encoder is damaged; check whether the rotary encoder wiring is desoldered (whether the aviation plug seat is in good contact); each single machine shell (PE terminal) shall be separately grounded to a main grounding point, which shall be reliably grounded There shall be grounding piles that meet the requirements of electrical grounding. It is not allowed to connect the single machine shell (PE terminal) in series and then ground, otherwise, interference pulse will be introduced, resulting in inaccurate cutting length;

11. Coextrusion problem

Co extrusion marking strip diffusion: generally, it is caused by improper selection of CO extrusion materials used by users. PE and other special materials shall be used, and the temperature of extrusion section can be reduced if necessary;

The coextrusion identification strip cannot be extruded: shut down the main extruder, start the coextrusion machine first, and then start the main extruder for about 10 minutes;

Too thin or too wide coextrusion identification strip: generally, it is caused by the mismatch between the extrusion amount of coextrusion machine and the traction speed of pipe, which should be adjusted

The frequency of coextrusion frequency converter or traction speed can be changed to match the two speeds;

The second reason is that the cooling water jacket in the blanking section of the coextrusion machine is not supplied with cooling water;

In the actual production process of pipe production line, there will be other abnormalities, which should be handled according to the actual situation.