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Common Mechanical Failures and Maintenance of Press Brake Bending Machines - II

Views:141     Author:Site Editor     Publish Time: 2020-11-09      Origin:Site

Fault 1. No slow down the movement of the slider

1-1. Whether the electromagnetic proportional directional valve has an electrical signal or whether the spool has any action or is stuck.

1-2. The system cannot build pressure.

1-3. The filling valve is stuck, or the filling valve sealing ring leaks.

1-4. Whether the slow valve has an electrical signal or is stuck.

1-5. Back pressure is too high or slows down pressure is too low.

press brake bending machine-1

Fault 2. When the slider moves slowly, it vibrates, swings, and makes noise

2-1. The pressure oil discharged from the cylinder contains air bubbles.

2-2. The friction force of the slide rail is too large, whether there is lubricating oil.

2-3. The gap between the fitting surface of the guide plate is large, or the top and bottom are uneven.

2-4. The level of the rack and workbench is not adjusted properly.

2-5. The balance valve is blocked.

2-6. Check if the quick-release valve is energized and opened.

2-7. The numerical control system parameter (gain), or the work feed speed setting is too large.

2-8. The backpressure valve is loose and the resistance on both sides is different.

2-9. Whether the solenoid proportional valve coil is biased and whether the neutral position signal of the proportional valve is correct.

2-10. Whether the signal of the proportional servo valve is disturbed, the inspection method is the same as above.

2-11. The piston rod is locked tightly by the oil cylinder sealing ring, and the resistance is large (change the PTFE hard sealing ring test).

2-12. The spherical washer on the grating ruler is not installed, the sliding seat does not move smoothly, and there is a problem with the grating ruler communication line.

2-13. The pressure curve is wrong, the pressure is not enough during work.

2-14. The pressure sealing O-ring of the filling valve produces a small amount of leakage.

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Fault 3. Large synchronization deviation when slowing down

3-1. Synchronous detection system failure (grating scale).

3-2. Proportional directional valve.

3-3. Leakage of quick lower valve.

3-4. The large gap in back pressure on both sides.

3-5. The oil temperature is too low.

3-6. Oil string in the upper and lower chambers of the cylinder.

3-7. CNC system parameters.


Fault 4. Bending angle error 

4-1. Check whether the compensation deflection of the compensation cylinder is large and the zero position cannot be completely restored.

4-2. Check whether the quick-clamp is loose.

4-3. Check whether there is any change in the bottom dead point of each bending.

4-4. Check whether the bow-shaped plate is installed properly and whether the screw hole is dead.

4-5. Changes in the sheet itself (thickness, material, stress).

4-6. Is the grating ruler loose?

4-7. Inaccurate positioning accuracy: Is the zero offset value of the proportional valve appropriate? The positioning cannot reach the bottom dead center, making it impossible to return.


press brake bending machine-3

press brake bending machine-4

Fault 5. Oil leakage in hydraulic lines or tubing burst

5-1. Check whether the oil pipe installation meets the requirements (extended length, pipe diameter, wall thickness, ferrule, the nut is too tight, too loose, bending radius, etc.).

5-2. Whether the tubing has impact or vibration.

5-3. Check whether the pipeline interferes or collides with other.

5-4. The pipeline is not fixed by pipe clamps.

press brake bending machine-5

Fault 6. Precautions during hydraulic system installation and maintenance

6-1. The valves sealed with paint shall not be disassembled by themselves, let alone adjusted.

6-2. The valve works normally after cleaning, it must be replaced with new oil and cleaned the oil tank immediately.

6-3. The oil pump shall not be subjected to any knocks or impacts during installation, and the oil pump must be refueled before testing.

6-4. When installing each valve, only its valve body can be transported, and no solenoid valve should be touched.

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