Three-station positive and negative pressure vacuum forming machine operation steps

• Power Supply: Verify that the rated voltage of 380V ± 5% is stable and that the independent power supply lines for the heating and vacuum systems at each workstation are intact.
• Air Source/Vacuum: Verify that the air compressor pressure (0.6-0.8MPa) is maintained, that the positive and negative pressure piping connections are leak-proof, and that the negative pressure gauge is set to zero.
• Core Components: The three-station mold (feeding, forming, and demolding) is securely fastened and free of foreign matter in the mold cavity. The heating plate (independent for each workstation), vacuum valve, and demolding cylinder are in good condition and free of deformation or sticking.
• Lubrication: Verify the lubrication of the drive rails and chains at each workstation to ensure there is no dryness or abnormal noise.

• Turn on the main power, then start the air compressor and vacuum pump in sequence. Wait until the vacuum pump negative pressure stabilizes (-0.08-0.09 MPa) and the air compressor pressure reaches the specified value.
• Workstation parameter settings:
  • Feeding station: Adjust the conveyor speed (5-10 m/min depending on the sheet thickness) and align the positioning block with the sheet edge.
  • Forming station: Set the heating temperature (90-160°C), heating time (15-35 seconds), positive pressure (0.4-0.6 MPa), and negative pressure hold time (8-20 seconds) based on the material (PVC/PET/PP).
  • Demolding station: Set the ejection cylinder stroke (to suit the product height) and ejection speed (low speed to prevent product damage).
• Test run: Manually trigger single-station operation to confirm smooth feeding, stable forming pressure, and no jamming during demolding. Then switch to "Automatic Mode."
• Mass production: Place the sheet into the feed port, and the machine will automatically complete the process. The cycle of "feeding → heating and softening → positive and negative pressure molding → cooling and shaping → demoulding and discharging" is synchronized at each workstation. The operator checks the product molding quality in real time and presses the emergency stop button when an abnormality occurs.

• Turn off "Auto Mode," clear any remaining sheet material from each workstation, and manually operate the demolding station to ensure there are no products in the mold.
• Turn off the heating switch and wait until the temperature of the heating platens at all workstations drops below 50°C.
• Turn off the vacuum pump first, and after the negative pressure gauge returns to zero, turn off the air compressor to release any residual pressure in the pipelines.
• Clean the molds and conveyor belts at each workstation, turn off the main power supply, and cut off the air supply.

1. Cleaning: Wipe any remaining material from the three-station mold cavity with a dry cloth, clean the surface of the heating plate (after cooling down after powering off), and purge any dust from the conveyor belt.
2. Sealing Check: Test the positive and negative pressure piping connections with soapy water. If there are no bubbles, the seal is normal; otherwise, replace the sealing ring.
3. Status Recording: Record the heating temperature deviation at each station (≤±5°C is normal) and the operating noise of the vacuum pump (no sharp or unusual sounds). Any abnormalities should be noted promptly.

1. Vacuum pump maintenance:

• Replace the vacuum pump oil (one month after initial use, and every three months thereafter). Use the amount indicated by the center line on the oil gauge. Drain any remaining oil completely.
• Clean the filter inside the pump, wipe it with alcohol, let it dry, and reinstall.

2: Heating system:

• A: Check the heating bricks' heating performance every six months for cracks, damage, or localized discoloration. Use an infrared thermometer to measure the temperature of different areas on the brick surface to ensure uniform temperature distribution. If significant temperature deviation is detected, further investigation is needed to determine whether the heating brick itself is faulty or if there is a problem with the electrical connections.
• B: Regularly inspect the high-temperature wires for wear and damage. Because they are exposed to high temperatures and vibration during equipment operation, the sheathing can be easily damaged. If damage is detected, promptly wrap or replace the wire to prevent short circuits and electric shock.
• C: Ensure the thermostat's installation environment is dry, well-ventilated, and at a suitable temperature weekly. High or low temperatures, as well as humidity, can affect the module's performance and lifespan. Clean dust and debris around the thermostat monthly to prevent heat dissipation.

3: Transmission components:

• A. Check the chain and gears for wear every six months. If gears are severely worn, replace them promptly. Also, regularly add gear oil to the gears to ensure proper lubrication.
• B. Adjust the cylinder stroke at the demolding station to ensure that the product does not collide with the mold after ejection. Replace the cylinder seals if necessary.
• C. Apply high-temperature grease to the guide rails and chains of the three stations (5-10g per station), and lubricate the conveyor belt bearings.
• D: Tighten: Tighten the mold fixing bolts and heating tube terminals at each station individually (torque 5-8N·m) to prevent loosening and positioning errors.

1. Overall Connection Logic: The air compressor generates compressed air, which is connected via pipes to the positive-pressure air inlet of the three-station positive-negative pressure vacuum forming machine, providing positive pressure for the forming process. The vacuum pump is connected to the negative-pressure port of the forming machine to create a vacuum to assist in the forming process. The chiller is connected to the forming machine's cooling system via cooling water piping to ensure that the temperature of key components (such as the mold) remains within the appropriate range during operation, ensuring product quality and stable operation.
2. Pipe Size
   • Positive-pressure piping from the air compressor to the forming machine: Typically, metal piping with an inner diameter of 32mm (such as galvanized steel) or pressure-resistant rubber piping is used.
   • Negative-pressure piping from the vacuum pump to the forming machine: Typically, vacuum tubing with an inner diameter of 35mm is used, commonly made of PVC or rubber. Because negative-pressure systems require extremely tight sealing, these piping must exhibit excellent sealing properties.
   • Cooling piping from the chiller to the forming machine: Cooling water piping typically uses flexible hoses with an inner diameter of 25mm. Copper tubing has excellent thermal conductivity and is suitable for applications requiring high cooling efficiency. PVC tubing is cost-effective and corrosion-resistant. The chiller's water inlet and outlet pipes are connected to the molding machine's cooling medium inlet and outlet, respectively. The pipe diameter selection depends on the heat exchange capacity of the molding machine's cooling system. If the molding machine has a large mold and generates a lot of heat, a pipe with an inner diameter of 25mm can be selected to ensure cooling water flow rate and heat dissipation effect.