Production line malfunction

⑴ The outer surface of the plastic pipe is rough.

Adjust the process temperature: reduce the cooling water temperature to 20–25°C for PE pipe cooling; inspect the water lines for blockages or insufficient water pressure; check the heating bands on the barrel, die head, and other components for damage; adjust the water flow rate into the sizing sleeve; consult the raw material supplier regarding the parameters of this batch; verify the core temperature of the mold—if it exceeds the die‑zone temperature, lower the core temperature; clean the mold.

⑵ Grooves appear on the outer surface of plastic pipes.

Adjust the water pressure at the sizing sleeve outlet to ensure uniform water flow; adjust the nozzle angles inside the vacuum sizing box to achieve even cooling of the pipe; inspect the die, sizing sleeve, cutting machine, and other components for foreign matter, burrs, or other defects.

⑶ Grooves appear on the inner surface.

Check whether water has entered the inner tube; if so, firmly pinch the tube blank at the die exit to seal its internal cavity; reduce the mold temperature; clean and polish the mold.

⑷ Pipeline exhibits vibration rings

Adjust the water outlet of the sizing sleeve to ensure uniform water flow; regulate the vacuum levels in the two chambers, maintaining a slightly higher vacuum in the rear chamber than in the front chamber; verify that the vacuum sealing gasket is not overly tight; inspect the traction unit for any signs of vibration; and confirm that the main machine discharges material evenly.

⑸ No vacuum

Check whether the vacuum pump’s water inlet is blocked; if so, clear it with a needle‑like tool. Verify that the vacuum pump is operating normally. Inspect the vacuum piping for air leaks. Examine the small hole in the center of the mandrel‑clamping screw; if it is clogged, clear it with a thin wire.

⑹ Outer diameter dimensional deviation of pipe material

Adjusting the vacuum level can change the outer diameter; adjusting the drawing speed can also alter the outer diameter; and correcting the inner bore dimensions of the sizing sleeve is required.

⑺ Pipe roundness deviation

Adjust the nozzle angles in the vacuum sizing unit and the spray box to ensure uniform cooling of the pipe; check the water level and pressure gauge readings in both the vacuum sizing unit and the spray box to maintain a strong, adequate spray flow; monitor the water temperature in these units—if it exceeds 35°C, install a chilled-water system or add an additional spray‑cooling tank; inspect the water‑circulation lines and clean the filters; fine-tune the processing parameters; verify and correct the roundness of the inner bore of the sizing sleeve; and adjust the pipe‑guiding and clamping mechanism to address any ovality in the pipe.

⑻ Uneven wall thickness of the pipe material

Adjust the wall thickness on the mold; adjust the nozzle angles in the vacuum forming machine and the spray box to ensure uniform cooling of the pipe; regulate the water flow from the sizing sleeve to achieve even water distribution; disassemble the mold, inspect the mold screws for looseness, and retighten them.

⑼ Excessive plasticizing temperature

Adjust the process; modify the core heating temperature of the mold and implement ventilated cooling for the mold.

⑽ Inaccurate length measurement during cutting

Check that the counter‑wheel is securely pressed against the material; verify that the counter‑wheel is not swinging, and tighten the mounting bolts of the counter‑wheel bracket; inspect the limit switch of the cutting saw for damage; examine the rotary encoder for any defects; ensure that the encoder wiring has not come loose (and that the aviation connector contacts are making good electrical contact); each machine’s enclosure (PE terminal) must have its own dedicated grounding wire routed to a single, reliable common grounding point, which should be equipped with an earth electrode meeting the required electrical grounding standards. Do not connect the PE terminals of multiple machines in series for grounding, as this can introduce interference pulses and result in inaccurate cut lengths.