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Before repairing the injection molding machine, it is necessary to have a complete understanding of the machine's working principles, such as electrical, hydraulic, and mechanical principles. Secondly, it is necessary to follow the four steps of seeing a doctor in ancient times, namely looking, smelling, asking, and cutting. Keep a clear mind, don't be impatient, first figure out which aspect of the malfunction belongs to electrical, hydraulic, or mechanical. A simple distinction can be made by following the following steps:
The following are general faults and troubleshooting methods for reference
1、 The oil pump motor does not start
1. If the motor cannot rotate and emits an abnormal sound, immediately turn off the emergency stop button, check if the fuse is blown or loose, and then check if the three-phase power supply of the motor is normal
2. Press the motor start button, and there may be no sound from the motor. The button switch, AC contactor wire may be loose, or the thermal relay may act
3. The oil pump is stuck, causing the motor to not rotate (there is some noise from the motor at this time)
4. Motor burnt out, repair according to the original specifications and identify the cause (such as phase failure, overload, poor AC relay contacts, loose motor wire contacts, or unbalanced or unstable three-phase power supply voltage)
2、 The electric motor can rotate, but it does not generate pressure or the large pump does not generate pressure
1. The electromagnetic coil of the electromagnetic overflow valve or pressure proportional valve of the small pump is not suction or the internal valve core is stuck by debris. Remove and clean it, while checking whether the electromagnetic coil is burned, whether the wiring is loose, or if there is poor contact
2. Oil pump damaged, repaired or replaced
3. The oil level is too low, causing the pump to suction empty
4. Is the oil filter blocked
5. Is the motor reversed or swapped
6. There is air inside the oil pump, please release the air first
7. The main valve core of the control pump overflow valve is stuck, remove the overflow valve for cleaning
3、 Incoherent model
1. The wiring of the safety door travel switch is loose or damaged, and the safety door travel is not pressed down. Check SQ1, SQ2, and SQ3
2. SQ4 travel switch closed
3. Lock mode solenoid valve stuck or solenoid valve socket loose
4. The formation switch for the ejector pin retraction is not closed
5. System pressure not present: repair according to item (2)
4、 No injection or slow speed
1. Low injection pressure, too slow speed: Increase the injection pressure, increase the injection speed
2. Plastic heating temperature bottom: increase the temperature
3. Nozzle blockage, remove for heating and cleaning
4. The injection time is too short
5. Injection solenoid valve stuck
6. The injection solenoid valve should not be electrified. Check for electrical reasons
5、 Not molding or molding too slowly
1. The end travel switch of the mold has been closed, and the collision block of the travel switch has been opened,
2. One way throttle valve tightly closed
3. If the material temperature is too low, increase the material temperature
4. The plastic solenoid valve is stuck, remove it for cleaning
5. The pre molding pressure is too low, increase the pre molding pressure
6. Foreign objects entering the screw are jamming the screw. Disassemble the screw for cleaning, and clean the material barrel
7. Hydraulic motor faulty, bearing stuck
6、 When molding, the screw rotates but does not feed
1. High back pressure
2. Insufficient cooling water at the feeding port, causing the material inside the feeding port to "bridge"; Adjust the water volume and remove the plastic blocks with adhesive structures
3. Shortage of materials, adding materials
4. Screw breakage
5. Setting the back pressure too high or too low
7、 Unable to adjust or difficult to adjust the mold
1. System pressure regulation too low
2. The pull rod nut of the rear template is stuck due to impurities or lack of lubricating oil and grease; Clean the pull rod nuts and repair them. During installation, pay attention to ensuring that the axial clearance of the four nuts is consistent, and then add lubricating grease
3. Mold regulating solenoid valve stuck or socket loose: inspection and repair
4. Damaged hydraulic motor for mold adjustment, repaired or replaced
8、 Hydraulic oil stability too high
1. Excessive oil pump pressure: Adjust the working pressure appropriately according to the plastic molding process
2. Insufficient oil in the fuel tank: add enough hydraulic oil
3. The oil cooler has been used for too long and is filled with scale, resulting in poor cooling effect. Clean the cooler
4. Insufficient cooling water flow rate or insufficient cooling water temperature
9、 Semi automatic operation failure
The semi-automatic operation of this machine is initiated by opening the safety door, closing the travel switch, sending a signal to initiate the semi-automatic action of the machine, and then closing the mold. When it touches the SQ4 travel switch, the mold closing ends and injection begins. The injection time relay starts timing, and when the injection time is up, the injection begins. When it touches the travel switch that ends the injection, flow prevention begins. When it touches the travel switch that prevents flow, the cooling time relay starts timing, After the time is up, perform the mold opening action, then open the mold. When it touches the end of the mold opening travel switch, perform the ejection action. When it touches the end of the ejection travel switch, perform the ejection action. When it touches the end of the ejection travel switch, wait for the safety door to open. In this way, the work repeats itself. As can be seen from the above, if manual operation is normal, it is generally caused by the lack of signals from the travel switch and time relay. Based on which stage of the mechanical cycle the semi-automatic action fails, compare the electrical and hydraulic schematic diagrams to identify the corresponding control components, inspect and solve them.
No.16-1 Youyi North Road, Boyi Industrial Park, Zouqu Town, Zhonglou District, Changzhou City