Analysis and elimination of common faults of CNC bending machine

　　1、 The noise and vibration of the oil pump is too large (too fast heating), and the oil pump is damaged

　　1. The oil pump suction pipeline leaks or the oil tank liquid level is too low, causing the oil pump to empty

　　2. The oil temperature is too low and the oil viscosity is too high, resulting in high oil absorption resistance

　　3. The oil filter at the oil suction port is blocked and the oil is dirty

　　4. Pump damage (injury during pump installation) caused by rough operation

　　5. Coupling installation problems, such as axial tightness, motor shaft and oil pump axis are not concentric

　　6. After the pump is installed, it reverses for a long time or there is no refueling

　　7. The outlet high-pressure oil filter is blocked or the flow is not up to standard

　　8. The oil pump is empty (there is oil, but there is air at the oil suction port of the oil pump)

　　9. If it is a plunger pump, the height of the oil return pipe may be too low

　　10. If it is hoeberger, the oil pump may be deflated

　　11. Oil temperature is too high, resulting in viscosity reduction (within 60 ° C)

　　12. The hydraulic oil contains water, which will cause the high pressure filter element to be blocked and damaged

　　2、 No pressure on the system

　　1. The steering direction of oil pump is wrong or the oil pump is damaged

　　2. Whether the pressure gauge is damaged

　　3. Whether the pressure control valve has electric signal or the valve is blocked

　　4. The pressure cartridge valve is blocked and jammed, and the oil cannot be sealed

　　5. The filling valve is stuck (the slide does not slow down)

　　6. The compensation amplifier is too small.

　　7. If the pressure can only reach a certain value, judge whether there is a problem with the valve oil pump by directly giving the pressure of 24 v

　　3、 Slow pressure build (Rexroth hydraulic system)

　　1. The damping hole at port X of pressure valve may be blocked

　　2. The cartridge valve at the pressure valve may not act flexibly

　　3. Possible electrical problems: test the solenoid pressure valve with the voltage of 24 V directly, or test the valve core of the electromagnetic pressure valve with something

　　4. Is the high pressure oil filter blocked

　　4、 There's a pounding sound when you're going down

　　1. Impact sound caused by loose guide plate

　　2. The position of black film of grating ruler is wrong

　　3. The setting value of delay parameter before fast down is too small

　　5、 There is no quick down movement of the slider

　　1. Is there any electric signal or jamming of quick down valve

　　2. Whether the electromagnetic proportional directional valve has electric signal or whether the valve core acts or is stuck (check the feedback voltage)

　　3. The mechanical part is too tight, such as the rail plate is too tight, and the oil cylinder is too tight

　　Therefore, the oil filling valve cannot be opened

　　5. Grating ruler

　　6. Check whether the foot switch is in good condition and check the wiring

　　7. After the slow down valve is powered on, the filling valve is closed, and the upper chamber cannot absorb oil

　　6、 The pause time of sliding block speed conversion point is long

　　1. The upper chamber of the oil cylinder inhales air, and the pressure is established for a long time (air leakage in the self-priming pipeline)

　　2. The flow rate of filling valve or Self-priming pipeline is small, or the sliding block moves down too fast to cause vacuum suction

　　3. The filling valve is not completely closed, and the pressure of upper chamber decreases slowly.

　　4. After the slow down valve is powered on, the filling valve is closed, and the upper chamber cannot absorb oil

　　5. The center position of proportional valve is not correct, which leads to different opening and asynchronous running

　　6. Is the test stopped when the speed is reduced

　　7. The quick down pressure has an effect on the closing of the filling valve, so the quick down pressure can be eliminated

　　8. Pressure parameter adjustment in delay stage before work in

　　9. The damping hole of the control pipeline of the filling valve is too small to form a differential pressure

　　10. CNC system parameters (delay before slow down)

　　11. Numerical control system parameters (slow down gain parameters decrease)

　　7、 There is no slow down action of the slider

　　1. Whether the electromagnetic proportional directional valve has electric signal or whether the valve core acts or is stuck

　　The pressure system cannot be established

　　3. The filling valve is stuck or the sealing ring of the filling valve leaks

　　4. Whether the slow down valve has electric signal or is stuck

　　5. The back pressure is too high or the slow down pressure is too low

　　8、 The sliding block vibrates, vibrates and makes noise when it moves slowly

　　1. The pressure oil discharged from the oil cylinder contains bubbles

　　2. The friction of slide guide is too large, and is there any lubricating oil

　　3. The gap between the joint surface of guide rail plate is large or uneven

　　4. The level of rack and worktable is not adjusted well

　　5. The balance valve is blocked

　　6. Check whether the quick down valve is powered on and opened

　　7. The parameter (gain) of numerical control system or the setting of working speed is too large

　　8. The back pressure valve is loose and the resistance on both sides is different

　　9. Whether the solenoid proportional valve coil is biased and whether the proportional valve center signal is correct

　　10. Check whether the signal of the proportional servo valve is disturbed, and the inspection method is the same as above

　　11. The oil cylinder sealing ring locks the piston rod with high resistance (test for replacing PTFE hard seal ring)

　　12. The spherical washer on the grating ruler was not installed, the sliding seat did not move smoothly, and there was a problem with the communication line of the grating ruler

　　13. The pressure curve is not correct, and the pressure is not enough when working

　　14. A small amount of leakage occurred in the O-ring of the pressure seal of the filling valve

　　9、 In slow down, the synchronization error is large

　　1. Failure of synchronous detection system (grating ruler)

　　2. Proportional directional directional valve

　　3. Leakage of quick down valve

　　4. There is a big gap of back pressure on both sides

　　5. The oil temperature is too low

　　6. The upper and lower chambers of the oil cylinder are filled with oil

　　7. Numerical control system parameters

　　10、 The sliding block vibrates and shakes when the pressure is kept at the bottom dead point

　　1. There may be something wrong with the grating ruler

　　2. The pressure oil discharged from the oil cylinder contains bubbles

　　3. The balance valve is blocked

　　4. CNC system parameters (gain)

　　5. The back pressure valve has different resistance on both sides

　　6. Problem of solenoid proportional valve: the middle position may be wrong

　　7. The lifting bolt of oil cylinder is loose → the bottom dead center shakes, the contour is not correct, the bending angle is not correct, and there is a sound when bending