Maintenance Guide for Your Fully Automatic Pipe Bending Machine

When maintaining and troubleshooting fully automatic pipe bending machines, the core principle is to disassemble the machine into individual components and inspect them one by one. By first confirming the status of the normal components, the scope of the fault can be quickly narrowed down, ineffective troubleshooting can be avoided, and maintenance efficiency can be improved. The following sections, categorized by component, detail the maintenance points and troubleshooting methods.

I. Hydraulic System Maintenance and Troubleshooting

The hydraulic system is the core of the pipe bending machine’s power transmission. Key attention must be paid to its sealing performance, pressure stability, and component operating status. This includes four key components: pump and motor, pressure reducing valve, hydraulic cylinder, and directional valve.

1. Pump and Motor
Maintenance Points
• Regularly check the connection between the pump body and motor for looseness to ensure smooth transmission;
• Clean dust from the motor surface to prevent overheating due to poor heat dissipation;
• Check the lubrication of the motor bearings and replenish with special grease every 3 months.

Troubleshooting (Symptom: Pump and motor do not operate under emergency stop conditions)

a. First, check the emergency stop system: Confirm that the emergency stop button is pressed. If pressed, rotate it clockwise to reset it. Also, check if the emergency stop circuit wiring is loose or broken.

b. Check the overload protection device: Check if the motor overload circuit breaker has tripped. If it has tripped, wait for the motor to cool down before resetting. Also, check if the load is too high (e.g., abnormal hydraulic system pressure).

c. Verify the power supply and fuse: Check if the motor power supply fuse is blown. If blown, replace it with a fuse of the same specification (refer to the rated current specified in the equipment manual).

d. Confirm voltage compliance: Use a multimeter to measure the voltage at the motor starter input terminal. It must match the equipment’s rated voltage to avoid the motor failing to start due to excessively high or low voltage.

2. Pressure Reducing Valve

Maintenance Points

• Perform monthly pressure calibration of the pressure reducing valve to ensure the output pressure remains stable within the equipment’s required range (refer to the equipment parameter table);

• Disassemble the pressure reducing valve every 6 months, clean impurities from the valve body, and check the valve core for wear. Replace any aged seals promptly.

Troubleshooting (Symptoms: Abnormal pressure, such as excessively high, low, or fluctuating pressure)

a. Manual Mode Test: Switch the equipment to manual operation mode and observe whether the pressure gauge reading matches the set value. If not, recalibrate using the pressure reducing valve adjustment knob;

b. Test Mode Verification: Enter the equipment test program, start the pressure reducing valve pressure test function, and record the pressure change curve. If the curve fluctuates beyond ±0.5MPa, disassemble and check if the valve core is stuck;

c. Check Tank Sealing: Observe whether the tank level drops abnormally. Also check for oil leaks at the tank welds and interfaces. If leaks are found, replace the gasket or repair by welding. After repair, replenish to the standard level (midpoint of the tank scale).

3. Hydraulic Cylinder

Maintenance Points
• Inspect the piston rod surface weekly. If scratches or rust are found, sand them with fine sandpaper and apply anti-rust oil immediately.
• Check the sealing caps at both ends of the cylinder for leaks. Replace the sealing rings every 3 months (it is recommended to use nitrile rubber material resistant to high-pressure hydraulic oil).
• Adjust the cylinder stroke limit to ensure the soft pad (buffer device) is properly set to prevent the piston from impacting the cylinder bottom or cylinder head.

Troubleshooting

a. Oil Leakage Inspection: Focus on checking the contact area between the cylinder piston rod and the sealing cap, and the connection area between the cylinder barrel and the end cap. If oil leakage is found, replace the corresponding seals and clean the leaking area to prevent oil contamination of other components.

b. Soft Pad Function Verification: Manually operate the cylinder reciprocating motion to feel for any obvious impact at the end. If there is, adjust the soft pad position or replace the aged buffer pad to ensure there is no rigid impact when the cylinder starts and stops (a buffer stroke of 5-10mm is recommended).

4. Directional Valve
Maintenance Points
• Check the directional valve wiring terminals monthly for looseness. Tighten the wiring with a screwdriver to prevent poor contact.
• Clean the directional valve body surface with compressed air every 6 months to prevent impurities from entering the valve body cavity.

Troubleshooting (Symptoms: Directional valve does not operate or operates abnormally)

a. Check the connecting cable: Disconnect the equipment power supply, unplug and plug the connecting cable between the directional valve and the controller, and check if the plug pins are bent or oxidized. If oxidized, clean with an alcohol swab.

b. Verify the I/O board fuse: Open the I/O board cover and check if the fuse in the corresponding directional valve circuit is blown (Note: Do not judge the fuse’s condition solely by the LED status, as a damaged LED may lead to misjudgment; use a multimeter to measure fuse continuity).

c. Diagnostic function test:

◦ First, remove the pipe bending fixture (to avoid accidental operation and damage to the workpiece), enter the equipment control diagnostic mode, manually send a directional valve start signal, and observe whether the valve operates.

◦ If it still does not operate in diagnostic mode, turn off the power and use an Allen wrench to press the manual button on the directional valve. Test one direction first, then switch to the other direction. If the valve operates normally when manually pressed, the valve body is not faulty, and the control signal or I/O board output needs to be checked. If it still does not operate when manually pressed, the directional valve needs to be replaced.

II. Inspection of Mechanical Components of the Fully Automatic Pipe Bending Machine
Mechanical components directly affect the bending accuracy, so it is crucial to check the reliability of connections and the condition of wear. The key inspection areas are as follows:

1. Clamping Die and Anti-wear Strip:

◦ Check if the bolts connecting the clamping die and the hydraulic cylinder are loose. If loose, tighten them using a torque wrench according to the equipment manual (common torque value is 25-35 N·m);

◦ Check the wear degree of the anti-wear strip surface. If the wear depth exceeds 1 mm or cracks appear, replace it promptly to avoid scratching the pipe;

◦ Clean metal debris between the clamping die and the anti-wear strip to prevent debris from getting stuck and affecting the clamping die’s closing accuracy.

2. Other Connections:

◦ Check the connection between the feeding mechanism, the bending die, and the equipment frame to ensure there is no looseness or displacement;

◦ Check the meshing of the transmission gears and chain. If the chain is loose, adjust the tensioning device and add gear lubricating oil (lithium-based grease is recommended).

III. Electronic System Diagnosis (Based on Diagnostic Screens and Drawings)

Electronic systems are responsible for signal transmission and control. Accurate fault location requires diagnostic tools and drawings. The core steps are as follows:

1. Control Signal Verification

• Signal Sending Check: Check on the diagnostic screen whether the controller is sending signals to the target component (e.g., directional valve, motor). If “Not Sending” is displayed, check if the control program is abnormal (e.g., incorrect parameter settings). If necessary, reload the device’s default program.

• I/O Board Signal Reception Confirmation: Refer to the device’s electrical diagram to locate the corresponding I/O board interface for the target component. Observe whether the LED indicator at the interface is lit (if the LED is not lit, check if the communication line between the controller and the I/O board is open or closed).

• Output Signal Detection:

◦ Use a multimeter (DC voltage range) to measure the voltage at the I/O board output terminals. If the device’s rated voltage is 24V, the normal output voltage should be between 22-26V.

◦ If signal waveform testing is required, use an oscilloscope connected to the I/O board’s internal circuitry to observe whether the waveform is continuous and free of noise. If the waveform is abnormal, the I/O board module needs to be replaced.

2. Switch Feedback Diagnosis

• Feedback Signal Check: Operate the device in diagnostic mode (e.g., press the emergency stop button, trigger the limit switch), and observe whether the diagnostic screen displays “Feedback Normal”. If it displays “No Feedback”, check whether the switch wiring is loose or whether the switch body is damaged (a multimeter can be used to measure the switch’s on/off state);

• I/O Board Signal Conversion Confirmation: Note that the I/O board has the function of converting serial signals to parallel signals. If signal conversion abnormalities occur (e.g., serial signals cannot be converted to parallel signals), check whether the I/O board conversion module is faulty. If necessary, contact the manufacturer to replace the dedicated module.

IV. Daily Maintenance Schedule for Fully Automatic Pipe Bending Machine

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