17 Press Brake Common Failure Analysis – With Detailed Reasons and Measures

If you’re press brake operators, you should read below 17 press brake common failure analysis carefully, probably it will help you solve big problems.

press brake troubleshooting

The main motor of press brake can not be started

Reason:

1, the start circuit of main motor failure, such as: not release emergency stop button, cable wiring loose, 24V control power;

2, the relevant components of the main motor’s start part failure, such as: thermal relays, circuit breakers, overload protection or damage of AC contactors;

3, power problems;

Measures:

1, check whether the emergency stop the main motor’s start the circuit is not released, loose wiring, 24V control power;

2, check whether the components of the main motor’s starting circuit part of are overload protection, if yes, then analyze the reasons, check whether the components damaged;

3, check whether the three-phase power is normal;

 

The press brake slider can not be quickly down

Reason:

1, slider rail tuning too tight;

2, backgauge axis is not in place;

3, the slider is not at the top dead center position;

4, foot switch signals did not enter the module;

5, the malfunction of proportional servo valve;

Measures:

1, check whether the slider rail is appropriate;

2, check whether there is a cursor of the X-axis actual position on the controller, or to check whether the backgauge programming value and the actual value is consistent in the manual interface;

3, the Y-axis state should be “1” on the controller, if it is “6”, check the actual coordinates of the Y axis, the value should be less than the difference between the Y axis and return;

4, according to electrical schematics, check whether the input signals of foot switch are normal;

5, check whether the proportional servo valve feedback is normal;

 

The press brake slider can not bend or bending speed is very slow

Reason:

1, the slider is not at the speed conversion point;

2, the set of the parameters of Y-axis bending is not good;

3, the pressure is not enough, such as: programming, machine tool parameter settings, hydraulic;

Measures:

1, check whether the Y-axis state from “2” to “3”, Y-axis actual value should be greater than the speed conversion point value, if not need to adjust the parameters of the fast forward part;

2, re-adjust part of the parameters the Y-axis bending;

3, check whether the programming operation is not right, or parameter settings is wrong, or hydraulic problems; can use pressure gauge, multimeter to detect the main pressure and proportional pressure valve signal, and then check whether the proportional pressure valve, the main valve is stuck and then check the filter and oil, and finally check the pump and its coupling;

 

The slider can not return during bending process

Reason:

1, cannot return without load, maybe the parameter’s problem or hydraulic failure;

2, can not return during bending, the workpiece angle does not meet the set value;

3, can not return during bending, the workpiece angle has exceeded the set value;

Measures:

1, debugging the parameters of Y-axis, bending parameters should be based on actual debugging, part of the gain is too small, the slider cannot bend or not bend well, too much slider will shake, the parameters should be adjusted during the action the slider do not shake or a little bit more of the gain. Or the bias settings of the left and right valve are not good in diagnostic procedures. If too small Y-axis cannot be in place, if too large Y-axis cannot unload; If it is hydraulic failure, need to check the main pressure, check whether the PV valve S5 has been in the power position;

2, probably the gain set of Y-axis parameter is too small, can increase properly, or pressure is not enough, analyze the reason why the pressure is not enough. It is because of the program or signal, hydraulics; programming reasons include mold selection, plate thickness, materials, workpiece length, bending method, etc.; hydraulic reasons include: hydraulic pump leakage, the proportional pressure valve is contaminated or damaged, the filter is blocked, whether the oil has been polluted;

3, mainly the programming and operating reasons, check the program and the workpiece;

 

Slider moving is not good

Reason:

1, the tightness of slider rail is not appropriate;

2, slider lock nut loose;

3, machine parameters need to be adjusted;

4, the gain, zero points on the amplifier of proportional servo valve need to adjust;

5, the back pressure valve pressure is not correct or the two sides are the imbalance. Back pressure setting is too small, the slider will slowly decline, and will shake during working process; two sides back pressure is imbalance, the slider will twist during running;

Measures:

1, re-adjust the guide clearance;

2, re-locking, if the lock nut and screw are too loose, need to be replaced;

3, if there is reference curve, should be adjusted according to the reference curve;

4, only BOSCH, REXROTH valve can be adjustable, but need to be cautious;

5, use pressure gauges to adjust the pressure of the back pressure valve, and make the two sides consistent;

 

The main motor automatically stops, heat relay, circuit breaker protection

Reason:

1, the proportional pressure valve, the main valve was stuck, the machine has been in the state of pressure-adding;

2, filter plug blocked, the oil movement is not smooth, the pump pressure has been high;

3, the use of oil for too long, has been contaminated;

4, poor oil quality;

5, circuit breakers, thermal succession problems, fail to reach the rated current;

6, the failure of pressure output controlled by the system, and send the wrong signal, so that the proportional pressure valve worked all the time;

Measures:

1, cleaning the proportional pressure valve, the main valve;

2, replace the filter and check the pollution degree of the oil;

3, immediately replace the oil filter;

4, replaced with the recommended oil;

5, replace the circuit breaker, overheat switch;

6, check the system output;

 

Hydraulic valve is stuck

Reason:

1, the use of oil for too long, has been contaminated;

2, poor quality of oil;

3, the rubber skin at the mouth of the oil tank aging;

Measures:

1, replace oil on time;

2, replace the recommended oil;

3, replace oil-resistant rubber sheet;

 

Press brake cylinder decline

Reason:

1, back pressure valve, the lift valve is dirty or damaged;

2, back pressure is small;

3, Glyd lap strain, wear;

4, cylinder inner wall damaged;

5, if the slider stopped at any position and slowly decline, if 5 minutes down less than 0.50mm, then it’s normal, this phenomenon is mainly caused by hydraulic oil characteristics;

Measures:

1, cleaning back pressure valve, lift the valve, if damage replaced;

2, re-adjust the pressure on the back pressure valve according to the standard;

3, replace the Glyd ring, and check the strain and wear causes of Gglyd ring,;

4, generally due to oil pollution, replace the cylinder, sealing ring;

5, no need to deal with;

When pressing the die of press brake, the height on both sides is inconsistent

Reason:

1, back pressure on both sides is inconsistent, back pressure setting may be high;

Measures:

1, adjust the back pressure to the specified value, to maintain consistency;

 

The slider is waiting too long at the speed transition point

Reason:

1, the tank suction port leak;

2, filling valve failure, such as the poor installation lead to the stuck of the valve core, or spring tension is not enough;

3, the set of Y-axis parameters is not good;

Measures:

1, check the sealing of the rubber sheet, re-install the cover here;

2, check the filling valve installation, check the running of the valve core, check the spring tension;

3, adjust the Y axis parameters;

 

The length and bending angles of the workpiece changes too much

Reason:

  1. Machine inertia parameter setting is not appropriate;
  2. sheet material;

Measures

  1. Re-adjust the machine inertia parameters;

2, check the sheet material;

 

When the workpiece has a multi-way bend, the size of cumulative error has too large errors

Reason:

1, the workpiece has too much bending steps, resulting in a large accumulation error;

2, unreasonable bending order;

Measures:

1, fine adjust the accuracy of each bend, so that the angle as far as possible in the negative difference, the size as accurate as possible;

2, adjust the bending sequence if possible;

 

The automatically calculated pressure from the press brake controller is greater than the die impedance

Reason:

1, the selection of lower die during programming mode is unreasonable;

2, the set of mold impedance is not correct;

3, the programming bending method is chosen wrong;

4, the machine constant parameters are modified, such as material parameters, unit selection;

Measures:

1, should select the toolings according to the relationship between the plate thickness and V slot width of lower die;

2, the correct set of mold impedance;

3, check the program;

4, check the machine tool constant parameters;

 

When programming large circular arc bending, the system is calculated to be slow or dead

Reason:

1, the programmed value of the X value exceeds the maximum value of the X-axis in the parameter;

Measures:

1, check the program;

 

The press brake hydraulic oil temperature is too high

Reason:

1, hydraulic failure, such as the filter is blocked, oil pollution, deterioration, etc;

2, long hours work under high pressure;

Measures:

1, check the filter, oil, if necessary, replacement;

2, check the reasons for long hours high-pressure work, is the actual needs, or other reasons;

 

The angles of fabricated workpiece is not accurate

Reason:

  1. If the error is very large, it may be programming error, slider connection loosening, grating ruler failure;
  2. if small error, you can correct the parameters in the controller, after the amendment can work stably, then is it normal;
  3. Unstable angle, often change, maybe caused by the slider loose, grating ruler failure, metal materials;

Measures:

1, check the running procedures, focusing on inspection whether the mold, material, thickness, the length of the workpiece, bending mode in the procedures is consistent with the actual operation; whether slider connection is loose, the grating connection is firm;

2, the small error may be caused by a variety of reasons, such as: the thickness of the programmed material and the actual use of the thickness has a little difference; material uniformity, mold wear, and operation reasons;

3, check the Y-axis re-positioning accuracy, check whether the slider connection, the grating connection is normal, if normal, it is likely caused by the plate materials;

 

The fabricated workpiece size is not accurate

Reason:

1, the size of instability, often change, maybe caused by the press brake machine power supply, servo drive, servo motor encoder and related cables, systems, screw mechanical connection, timing belt (wheel) factors;

2, the size of the deviation, but stable, and most caused by the parallelism, straightness of backgauge beam, and parallelism, vertical degree of the back stopper;

3, when positioning by the bending edge, if the bend angle is greater than 90 degrees, resulting in small positioning distance;

Measures:

1, check the backgauge axis repeat positioning accuracy, generally, less than 0.02mm, if differentiate too much, need to check the possible factors, if caused by the servo drive, servo motor encoder, controller, best to deal with by the manufacturer;

2, first check the parallelism and straightness of the beam, and then check the parallelism, vertical degree of the back stopper;

3, if positioning by the bending edge, try to make this bend not greater than 90 degrees;

>> You can also check out The Ultimate Guide to Press Brake (2018 Updated) to fully understand things about press brake.

2018-01-17T10:35:45+00:00 Bending|

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