Analysis and elimination of common faults of CNC bending machine

I. Excessive noise of the oil pump (too fast heating) and damage of the oil pump

1. The suction pipe of the oil pump leaks or the liquid level of the oil tank is too low, resulting in the suction of the oil pump

2. The oil temperature is too low, the viscosity of oil is too large, resulting in large oil absorption resistance

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

4. Pump damage (pump installation injury) by any knocks

5. Coupling installation problems, such as axial tightness, motor shaft and oil pump shaft are different

6. After pump installation, the test machine will reverse for a long time or there is no refueling

7. The outlet high-pressure oil filter is blocked or the flow rate cannot reach the standard

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

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

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

11. Oil temperature is too high, resulting in low viscosity (less than 60°C)

12. Hydraulic oil contains water, which will lead to blockage and damage of the high-pressure filter element

Two, the system has no pressure or pressure can not be built up

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

2. Check whether the pressure gauge is damaged

3. Pressure control valve has no electrical signal or valve blockage

4. The pressure cartridge valve is blocked and stuck, which can not seal the oil

5. Liquid filling valve stuck (slide block does not slow down)

6. The compensation amplifier is too small.

7. The pressure can only reach a certain value, and the method of directly giving 24V is used to determine whether there is a problem with the valve oil pump

Three, the pressure is built slowly (REXROTH hydraulic system)

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

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

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

4. High pressure oil filter is not blocked

Four, there is a sound of impact

1. Impact sound caused by loosening of guide board

2. The black piece of grating ruler is not in the right position

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

Five, the slider has no fast down action

1. The quick down valve has no electrical signal or is stuck

2. Solenoid proportional directional valve has no electrical signal or spool action, stuck (check the feedback voltage)

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

4. The liquid filling valve is closed and cannot be opened to absorb oil

5. Grating scale problem

6. Check whether the pedal switch is in good condition

7. Close the liquid filling valve after the valve is powered down slowly, and no oil can be absorbed in the upper chamber

6. Long pause time at the speed change point of the slider

1. Air is sucked into the upper chamber of the cylinder, and the pressure takes a long time to establish (air leakage from the suction road)

2. The flow rate of liquid filling valve or self-suction pipe is small, or the speed of sliding block is too fast, resulting in vacuum suction

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

4. Close the liquid filling valve after the valve is powered down slowly, and the oil cannot be absorbed in the upper chamber

5 proportional valve in the wrong lead to the opening is not the same, go out of sync

6. Fast down speed to reduce the test has no pause

7. The size of fast downpressure has an impact on the closing of the filling valve, so fast downpressure should be excluded

8. Pressure parameter adjustment in delay stage before work

9. The damping hole of the liquid filling valve control pipeline is too small, resulting in pressure difference

10. Numerical control system parameters (slow down before delay)

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

7. The slider has no slow down action

1. The solenoid proportional directional valve has no electrical signal or spool action, stuck

2. The system cannot build pressure

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

4. Slow down the valve whether there is electrical signal or stuck

5. Too high back pressure or too low slow downpressure

8. The slider vibrates, oscillates and makes noise when moving slowly

1. Oil cylinder discharge pressure oil contains bubbles

2. The friction of slide guide is too large, and there is no lubricating oil

3. The gap between the guide board's fitting surface is large, or uneven up and down

4. The rack and workbench level are not properly adjusted

5. Balance valve is blocked

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

7. Numerical control system parameters (gain), or work speed setting is too large

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

9 solenoid proportional valve coil has no bias, proportional valve signal is correct

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

11 cylinder seal ring to hold the piston rod, resistance (for ptfe hard sealing ring test)

12. The spherical washer on the grating ruler is not installed, the sliding seat does not move smoothly, and there is something wrong with the communication line of the grating ruler

13. Wrong pressure curve, insufficient pressure during working

14. Pressure seal O-ring of liquid filling valve produces a small amount of leakage

Nine, slow down the synchronization deviation is large

1. Synchronous detection system failure (grating ruler)

2. Proportional direction reversing valve

3. Quick down valve leakage

4. Large gap between back pressure on both sides

5. Oil temperature is too low

6. Oil is connected in the upper and lower cavities of the cylinder

7. Numerical control system parameters

10. The slide block oscillates and jitter when holding pressure at the bottom dead point

1. There may be a problem with the grating ruler

2. Oil cylinder discharge pressure oil contains bubbles

3. Balance valve is blocked

4. Numerical control system parameters (gain)

5. Back pressure valve problem, resistance on both sides is not the same

6 electromagnetic proportional valve problem: the median may not be right

7. The hanging bolt of the oil cylinder is loose → the bottom dead point is jitter, the contour is not correct, the bending Angle is not correct, and there is a sound when bending

11. No return action or slow return of the slider

1. Whether the solenoid proportional directional valve is reversed or damaged

2. Whether the system has established pressure, or the return pressure is too small

3. One of the filling valves may be stuck or not fully open

4. After the valve is powered down slowly, the liquid filling valve shall be closed, and the return journey cannot be fast

5. CNC system: the programming Angle is too small to reach the dead end of bending programming

6. Set the parameters of the NUMERICAL control system to zero

7. The grating ruler is damaged or the line is arranged

8. Check whether the system pressure builds slowly

Twelve, the slider back vibration, jitter

1. The return pressure is too high or too low

2. System parameters or PLC and DM02 modules

3. Whether the proportional valve coil is deflected

13. Slide block sliding (top dead center)

1. Adjust the back pressure valve

2. Back pressure valve leaks or fast down valve leaks

3. Oil is connected in the upper and lower cavities of the cylinder

4. Proportional valve bias

5. The stability of the sealing ring support is not enough, and the sliding block is shown after deformation

6. Determine the cause of slide - remove the proportional valve and observe whether the oil outlet in the lower chamber is oil

Fourteen, bending Angle error is large

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

2, check whether the fast clip diagonal cheese is loose

3, check each bending dead point is not changed

4, check whether the installation of the bow lever is standard, whether the screw hole is dead

5, the change of the plate itself (thickness, material, stress)

6. Whether the grating ruler is loose

7, positioning accuracy is not accurate: proportional valve zero bias value is appropriate, positioning can not be to the bottom dead point so that can not return

Fifteen, bending straightness error is large

1. Check whether the deflection of the compensation cylinder is appropriate

2, check whether the fast clip diagonal cheese is loose

3. Check whether the horizontal and vertical die fitting surface on the slider is deformed

4. Check whether the upper and lower molds are deformed

5, the change of the plate itself (thickness, material, stress)

6. Check whether the workbench (neutral board) is deformed

Sixteen, hydraulic pipeline oil leakage or oil pipe collapse

1. Check whether the tubing installation meets the requirements (extension length, pipe diameter, wall thickness, clamp sleeve, nut too tight, too loose, bending radius, etc.)

2. Whether the oil pipe has impact and vibration

3. Check whether the pipe interferes or collides with other pipes

4. Pipes are not secured by pipe clamps

17. Precautions for installation and maintenance of hydraulic system:

1. The valve of the paint seal shall not be removed by itself, nor shall it be adjusted

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

3, the installation of the oil pump shall not be beaten, impact, oil pump before the test machine to advance refueling

4, each valve installation can only carry its valve body, do not contact any solenoid valve

Analysis of common faults of rear stopper

1. The rear stopper cannot move: ① Check whether the driver has an alarm

② Check the limit switch of each shaft

③ Check the reliability of connectors

2. Drive alarm

3. X and R axes are not running smoothly with jitter

4, positioning accuracy changes: (1) mechanical problems (there is no loosening, impact)

② Electrical → one-way positioning

③ Parameter adjustment

(4) whether the tensioner wheel is loose and the screw connecting is loose

5. Overload alarm: Whether the ball screw can rotate easily, the steel ball may be damaged

6, R axis driver no. 16 alarm → gas spring failure

7. Z1, Z2 axis no. 22 alarm → replace the encoder cable

8. No. 38 alarm → The line connector is loose

9, servo motor noise: gain setting is too large