Solve common press brake faults

Oil pump motor cannot be started

Cause analysis:

1. The main engine starting circuit may have failed due to reasons such as the emergency stop button not being released, loose cable wiring, or a problem with the 24V control power supply.
2. Components in the starting part of the main engine may have failed, such as thermal relays, circuit breakers, or AC contactors that provide overload protection.
3. There may be a problem with the power supply.

Solution:

1. Check the main engine starting circuit for an emergency stop button, make sure it is released, and check for loose wiring and problems with the 24V control power supply.
2. Check the main motor starting circuit for overload protection components. If such components exist, analyze the causes of failure and check for damage.
3. Check the normal operation of the three-phase power supply.

The ram cannot descend quickly

Cause analysis:

1. The ram guide rail may be adjusted too tightly.
2. The backgauge shaft may not be in place.
3. The ram may not be in the top dead center position.
4. Failure of the pedal, relay and other components.
5. The proportional servo valve may be defective.

Solution:

1. Check that the ram guide rail is suitable.
2. Check whether there is a cursor at the actual X position in the system, or confirm whether the programmed value of the backgauge axis is consistent with the actual value in the manual interface.
3. The status of the Y axis in the system must be “1”. If it is “6”, check the actual coordinates of the Y axis, and the value should be less than the difference between the Y axis and the return.
4. Check whether the pedal, relay and other signals are normal according to the electrical schematic diagram.
5. Check whether the proportional servo valve feedback is normal.

The ram moves to bend or the bending speed is too slow

Cause analysis:

1. RAM memory may not reach the speed conversion point.
2. The parameter setting of the Y-axis folded part of the system may not be good.
3. Insufficient pressure, such as programming operation, machine tool parameter setting, hydraulic pressure, etc.

Solution:

1. Check whether the Y axis status changes from “2” to “3” and whether the Y axis actual value should be greater than the speed conversion point value. If not, adjust the fast forward parameters.
2. Readjust some Y-axis flexion parameters.
3. Check whether this is caused by programming operation, parameter setting or hydraulic pressure. With the help of pressure gauge and multimeter, first detect the signals of main pressure and proportional pressure valve, then check whether the proportional pressure valve and main pressure reducing valve are stuck, then check the filter element and fluid of oil and finally check the oil pump and its coupling.

Sometimes the ram fails to return when folding

Cause analysis:

1. During no load, the ram may not be able to return due to a parameter problem or hydraulic failure.
2. It is not possible to return during processing and the part angle does not reach the set value.
3. It is not possible to return during processing and the part angle has exceeded the set value.

Solution:

1. Debug some parameters of Y axis bending. The bending parameters should be adjusted according to the actual situation.

If the gain is too small, the ram will not bend or bend in place, and if the gain is too large, the ram will shake. The parameters must be adjusted so that the ram does not swing during the action and the gain is as high as possible.

Alternatively, check that the left and right valve offsets are set correctly in the diagnostic program. If the Y axis is too small it will not be in place and if the Y axis is too large it will not be unloaded.

If it is a hydraulic failure, check the main pressure and see if the photovoltaic valve S5 is always in the on position.

2. The gain of the Y axis bent part parameter may be set too small and can be increased accordingly. Or the pressure may not be enough. Analyze the reasons for insufficient pressure, whether for programming reasons or for signaling and hydraulic parts.

Programming reasons mainly include die selection, plate thickness, material, part length, bending mode, etc. The hydraulic reasons mainly include whether the oil pump leaks, whether the proportional pressure valve is polluted or damaged, whether the filter element is blocked, and whether the oil has been polluted.

3. Mainly for programming and operating reasons, check the programmed and processed parts.

Bad movement of the ram

Cause analysis:

1. Improper tightening of the ram guide rail.
2. The ram locknut is loose.
3. Machine tool parameters need to be adjusted.
4. The gain and zero position of the proportional servo valve amplifier need to be adjusted.
5. The pressure setting of the back pressure valve is incorrect or both sides are unbalanced. If the backpressure setting is too small, the ram will slide slowly and shake as the work progresses. If the back pressure is unbalanced on both sides, the ram will twist during operation.

Solution:

1. Readjust the guide rail clearance.
2. Block again. If the locknut becomes too loose on the bolt, it will need to be replaced.
3. If there is a reference curve, adjust it according to the reference curve.
4. Only Bosch and Rexroth valves are adjustable, but care must be taken.
5. Use the pressure gauge to adjust the pressure of the back pressure valve and make both sides consistent.

Sometimes the main motor stops automatically and is protected by thermal relay and circuit breaker

Cause analysis:

1. The proportional pressure valve and the main pressure reducing valve are stuck, and the press brake is always pressurized.
2. The filter element is blocked, the oil flow is not smooth, and the oil pump pressure is always too high.
3. The oil has been used for a long time and is polluted.
4. Poor oil quality.
5. If the circuit breaker and thermal relay do not reach the rated current, they will activate.
6. The control pressure output part of the system fails and sends wrong signals to make the proportional pressure valve work all the time.

Solution:

1. Clean the proportional pressure valve and main pressure reducing valve.
2. Replace the filter element and check the degree of oil contamination.
3. Change the oil immediately and replace the oil filter element.
4. Replace with recommended oil.
5. Replace the circuit breaker and thermal relay.
6. Check system output.

Any stuck valve

Cause analysis:

1. The oil has been used for a long time and is polluted.
2. Poor oil quality.
3. Whether the rubber skin on the oil inlet of the oil tank is aged.

Solution:

1. The customer is advised to change the oil on time.
2. Replace with recommended oil.
3. Replace the oil-resistant rubber plate.

Cylinder slides down

Cause analysis:

1. Dirty or damaged back pressure valve and lift valve.
2. Small backpressure.
3. The flu ring is tight and frayed.
4. The inner wall of the oil cylinder is tense.
5. If the ram stops at any position and slides slowly, it is normal for it to slide less than 0.50mm in 5 minutes. This phenomenon is mainly caused by the characteristics of hydraulic oil.

Solution:

1. Clean the back pressure valve and lift valve and replace them if they are damaged.
2. Readjust the pressure of the back pressure valve according to the standard.
3. Replace the locking ring and check the causes of tightness and wear of the locking ring.
4. Generally, replace the cylinder and sealing ring due to oil pollution.
5. No treatment is required.

When pressing the matrix, the height of both sides is inconsistent

Cause analysis:

The back pressure on both sides is inconsistent and the back pressure setting may be too high.

Solution:

Adjust the back pressure on both sides to the specified value and keep it consistent.

The waiting time at the speed conversion point is too long when the ram is moving

Cause analysis:

1. The oil suction port on the oil tank leaks.
2. If the charging valve fails, the valve core may become stuck due to improper installation or the spring tension may not be sufficient.
3. Y axis work progress parameters are not set correctly.

Solution:

1. Check the rubber plate seal and reinstall the cover plate.
2. Check fill valve installation, check valve core function, and check spring tension.
3. Adjust the Y axis work progress parameters.

The length angle of the part changes a lot during bending

Cause analysis:

1. Inadequate configuration of the machine inertia parameter.
2. Bending material.

Solution:

1. Readjust the machine’s inertia parameters.
2. Check the board material.

When the workpiece has multiple bends, the dimensional error of the accumulated error is very large

Cause analysis:

1. There are many bends in the workpiece, resulting in large cumulative errors.
2. Irrational push-up sequence.

Solution:

1. Adjust the precision of each fold to make the angle as negative as possible and the size as accurate as possible.
2. Adjust the bending sequence when possible.

The pressure automatically calculated by the system is greater than the matrix impedance;

Cause analysis:

1. Unreasonable selection of the lower module during programming.
2. The array impedance setting is incorrect.
3. The bending mode was not selected correctly during programming.
4. The parameters of machine tool constants are modified, such as material parameters, unit selection and other parameters.

Solution:

1. Select the die according to the relationship between the thickness of the plate and the bottom opening of the die.
2. Correctly set the array impedance.
3. Check the program.
4. Check the constant parameters of the machine.

When programming a large arc curvature, the system calculation becomes very slow or freezes;

Cause analysis:

The X value set during programming exceeds the maximum X axis value in the parameter.

Solution:

Check the program.

Oil temperature too high

Cause analysis:

1. Hydraulic failure such as blocked filter element, oil pollution, deterioration, etc.
2. Working under high pressure for a long time.

Solution:

1. Check the filter element and oil and replace if necessary.
2. Check whether the reason for prolonged work at high voltage is a real need or other reasons.

Inaccurate angle of machined part

Cause analysis:

1. If the error is very large, it could be a programming error, loose RAM connection, faulty grid ruler, etc.
2. It is normal that there is a small error and it can be corrected in the system. If it works stably after the correction, it is normal.
3. The angle is unstable and changes frequently, which may be related to the loose connection of the ram, failure of the grid ruler, material, etc.

Solution:

1. Check the running program, focusing on whether the mold, material, plate thickness, part length, and bending mode in the program are consistent with actual operation, whether the ram connection is loose, and whether the grid ruler connection is tight.
2. Normally, there is a small error, which may be caused by various reasons, such as error between the programmed material thickness and the actual thickness, material uniformity, die wear, operation and other reasons.
3. Check the accuracy of repeated positioning of the Y axis and check whether the ram connection and grid ruler connection are normal. If normal, it is probably material related.

Inaccurate size of the processed part

Cause analysis:

1. The size is unstable and changes frequently, which may be related to the machine tool power supply, servo drive, servo motor encoder and related cables, systems, lead screw mechanical connection, synchronous belt (wheel), etc.
2. The dimension is deviated but stable, which is mainly related to the parallelism, straightness, parallelism and perpendicularity of the backgauge beam.
3. When positioning with the folded edge, the bending angle is greater than 90°, resulting in a small size.

Solution:

1. Check the repeated positioning accuracy of the rear retaining shaft, which is generally less than 0.02 mm. If the difference is large, check the possible factors one by one. If it is caused by servo drive, servo motor encoder, system, etc., it is best to be dealt with by the manufacturer.
2. First check the parallelism and straightness of the beam, and then check the parallelism and perpendicularity of the stop finger.
3. If the folded edge is used for positioning, try to make this fold no more than 90°.