Before repairing the machine injection moulding hydraulic pump, first of all, you should have a completely clear understanding of the machine’s working principles, such as the electrical, hydraulic, and mechanical principles. Secondly, we should follow the four steps of the ancients to see the doctor, i.e. look, smell, ask, and cut. Keep a clear head, do not be hasty, and figure out what belongs to the electrical, hydraulic, and mechanical aspects of the fault, a simple distinction can be made according to the following steps:
I. The oil pump motor does not start
1. The motor does not turn while making an abnormal sound, immediately close the emergency stop button, check whether the fuse is blown or loose, and then check whether the motor’s three-phase power supply is normal
2. Press the motor start button, the motor rattles no possible button switch, the AC contactor line is loose, or the thermal relay action
3. The oil pump jam caused by the motor does not rotate (at this time the motor has some sound)
4. The motor burned out, according to the original specifications to repair and find the cause (such as phase break, overload, AC relay contact is not good, the motor line contacts loose, or three-phase power supply voltage imbalance, instability)
II. The motor can turn, but not pressure, or big pump does not start the pressure
1. Machine injection moulding oil pump repair solenoid relief valve or pressure proportional valve solenoid coil does not suck or internal spool is stuck by debris, remove and clean, while checking whether the solenoid coil is burnt, whether the wiring is loose, or poor contact
2. The oil pump is damaged, repair or replace the oil pump.
3. The oil level is too low, resulting in pump suction empty
4. Whether the oil filter screen is blocked
5. Whether the motor is reversed, change the phase
6. There is air inside the oil pump, first deflation
7. Control the pump relief valve of the main valve heart stuck, remove the relief valve cleaning
III. Non-moulding
1. The safety gate travel switch wiring is loose or damaged, and the safety gate trip is not pressed down, check SQ1, SQ2, SQ3
2. SQ4 travel switch is closed
3. Clamping solenoid valve valve stuck or solenoid valve socket loose
4. The ejector backward formation switch is not closed
5. The system pressure is not: according to (2) the contents of the repair
IV. Not injected or slow
1. Low injection pressure, speed is too slow: adjust the injection pressure, adjust the speed of injection
2. The bottom of the plastic heating temperature: raise the temperature
3. Nozzle clogging, remove the heating and cleaning
4. Injection time is too short
5. Injection solenoid valve stuck
6. The injection solenoid valve may not be electric, check the electrical causes
V. Not plastic or plastic too slow
1. Close the pre-plastic termination travel switch, then open the travel switch of the bumpers.
2. The one-way throttle valve is closed
3. Material temperature is too low, increase the material temperature
4. Pre-plastic solenoid valve stuck, remove and clean
5. Pre-plastic pressure is too low, raise the plastic pressure
6. Screw into the foreign matter stuck screw. Remove the screw cleaning, barrel cleaning
7. Machine injection moulding oil pump repair hydraulic motor bad, bearing jammed
VI. Pre-moulding screw rotation, but not into the material
1. Back pressure is too high
2. Feeding port out of the cooling water is not enough, feeding port material ‘bridge’; adjust the amount of water, take out the sticky structure of the plastic block
3. Lack of material, add material
4. Screw broken
5. The back pressure is too high, lower back pressure
VII. Can not adjust the mould or difficult to adjust the mould
1. Machine injection moulding oil pump maintenance pressure adjustment over the bottom 2. After the template tie rod nut due to impurities, or lack of lubricating oil and grease stuck; cleaning tie rod nut, repair, installation, pay attention to the axial clearance of the four nuts to be the same, and then add lubricating grease
3. Adjusting the mould solenoid valve stuck or loose socket: check, repair
4. Adjust the mould hydraulic motor damage, repair or replacement
VIII. Machine injection moulding oil pump repair hydraulic oil steady too high
1. The oil pump pressure is too high: according to the plastic moulding process to reduce the working pressure appropriately
2. Insufficient oil in the tank: add enough hydraulic oil
3. Oil cooler used for too long, accumulated scale, poor cooling effect, cleaning cooler
4. The cooling water flow is not large enough, or the temperature of the cooling water is not low enough
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