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Press Brake fault reasons and solutions

Press Brake fault reasons and solutions

1.Main motor doesn’t work

Reasons:

1、Start-up circuit failure: emergency button have not been released, cable connect became loose, 24V control power etc.

2、Components related to startup parts of main motor: thermal relay, circuit breaker, AC electric contactor etc overload protection or damaged.

3、Power problems

Reasons:

1、Start-up circuit failure: emergency button have not been released, cable connect became loose, 24V control power etc.

2、Components related to startup parts of main motor: thermal relay, circuit breaker, AC electric contactor etc overload protection or damaged.

3、Power problems

Solutions:

1、Inspect whether the emergency button have been released, cable connector became loose, 24V control power.

2、Inspect whether startup components of main motor are in overload protection state, if any, check whether some components have been broken down.

3、Check whether three-phase power be in good condition

2.Cam fail to travel down quickly

Reasons:

1、Cam guide rail too tight

2、Back gauge shaft is not in place

3、The cam doesn’t run to the death point position any

4、Signals form pedal switch and other parts not enter in the module

5、Ratio servo valve break down

Solutions:

1、Cam guide rail too tight

2、Back gauge shaft is not in place

3、The cam doesn’t run to the death point position any

4、Signals form pedal switch and other parts not enter in the module

5、Ratio servo valve break down

Solutions:

1、Inspect whether the cam guide rail is suitable

2、Inspect whether there are cursor on X actual position on controller, or, check whether the back gauge programming valve is consistent with actual value in manual interface

3、Y-axis state shall be ”1”, if”6”,check the actual coordinate of Y-axis, and the value shall less than the difference between Y-axis and return stroke

4、Inspect whether signals from pedal switch and other parts are normal

5、Inspect whether the ratio servo valve feedback is normal

Reasons:

1、The cam fail to arrive at transition point

Improper setting of parameters of Y-axis bending parts

Pressure is not enough, due to programming operation, parameter setting, or hydraulic pressure

Reasons:

1、Inspect whether Y-axis state have been changed into”3” from “2”, actual value of Y-axis shall be larger than the conversion value, if not, shall adjust the fast forward parameters

2、Readjust Y-axis bending parameters

3、Inspect and find out the true reason; first inspect the signals of main pressure and ratio pressure valve with help of pressure gauge, universal meter, then check whether the ratio pressure valve and main pressure relief valve have been blocked, then check the filter element and hydraulic fluid, finally check the oil pump and coupling.Cam sometime can’t return

Reasons:

1、Can’t return when no load, possible wrong setting parameters or hydraulic fluid failure

2、Cam can’t return when bending work pieces and the work pieces angle fail to reach the preset value.

3、Cam can’t return, but the work pieces angle exceed preset value

Solutions:

1、Debug parameters of Y-axis bending parts according to the actual state, if partial parameters gains too small, cam can’t fulfill bending task ideally, if too large, the cam will shake, or diagnose left and right valve offset setting, too small, Y-axis can’t be in place, too large, Y-axis can’t unload, if hydraulic reason, check the main pressure, check whether PV valve S5 is charged all the time;

2、Possible partial parameter gain setting is small, appropriately increase the value; if the pressure is insufficient, analysis its reasons, programming reason, signal or hydraulic pressure reasons; programming reason mainly including: die, plate thickness, material, length of work pieces, bending method, hydraulic pressure reason main including: leakage of oil pump, whether ratio pressure valve have been contaminated or damaged, and whether filter element have been blocked, and whether hydraulic fluid have been contaminated.

3、Programming and operation reason, check all programs and work pieces.

Cam doesn’t work smoothly

Reasons:

1、Cam guide rail became loosed

2、Lock nut of cam became loosed

3、Machine parameter need adjustment

4、Zero position of ratio servo amplifier shall be adjusted

5、Back valve pressure setting is not proper, or bilateral pressure uneven. If the back pressure is to small,  the slider will slip down slowly, and shake when work, it he back pressure is uneven, slider will twist when work

Solutions:

1、Readjust the guide rail gap

2、Re-locked up, if the nut can’t suit the screw properly, replace it

3、If there reference curve, adjust the machine parameters according to the curve

4、Only BOSCH、REXROTH valves are adjustable, shall carefully

5、Adjust the back pressure valve through pressure gauge, let the bilateral pressure consistent

6、Sometimes the master motor automatically stop work, perhaps the motor come into thermal relay or circuit breaker protection condition.

Reasons:

1、Scale pressure valve、master pressure relief valve have been blocked, the machine is in pressurized condition all the time.

2、The filter is blocked, oil not smooth, and oil pump pressure is always very high

3、Oil usage time is too long, have been contaminant.

4、Oil quality is too low

5、Circuit breaker、thermal relay go wrong, start work before reaching the rated current.

6、There is something wrong with system control pressure output which gives out wrong signal, scale pressure valve constantly works.

Solutions:

1、Clean the scale pressure valve and master pressure-relief valve

2、Replace the filter and check the contaminate degree of oil

3、Immediately replace the oil filter cartridge

4、Replace the oil we recommended for you

5、Replace the circuit breaker, thermal relay;

6、Check the system output

Solutions:

1、Clean the scale pressure valve and master pressure-relief valve

2、Replace the filter and check the contaminate degree of oil

3、Immediately replace the oil filter cartridge

4、Replace the oil we recommended for you

5、Replace the circuit breaker, thermal relay;

6、Check the system output

Solutions:

Oil usage time is too long, have been contaminated

Oil quality is too low;

Oil tank inlet rubber skin with or without aging

Solution

Advise the customer to replace the Press Brake oil on time

Use the recommended oil

Replace the oil resistant rubber plate

Press brake cylinder slips down

Reasons:

Back pressure valve or drive valve have been broke down

Back pressure is not enough

SPGO strain and wear

The cylinder interface strains

If the slider slips down where it stops and sliding distance less than 0.5mm within 5 mins, it’s ok, this phenomenon mainly caused by hydraulic oil properties

Solutions:

Clean the back pressure valve and driving valve, replace if breaks down

Readjust the pressure of back pressure valve according to standards

Replace the SPGO, and find out the reasons for strain and wear of SPGO

Generally, caused by contaminating oil, replace the cylinder and sealing ring

usually without treatment

Bilateral height of press brake is inconsistent when pressing

Reasons:

Bilateral back pressure is inconsistent, back pressure setting may be a bit high

Solutions:

Adjust the bilateral pressure to specified valve, remains consistent

Waiting time of slider at speed transition point is too long

Reasons:

Oil-sucking nozzle of tank leaks gas

Some faults with oil-infusing valve, such improper installation results in blocking of valve core, or spring tension is not enough

Parameter setting of Y-axis feed is wrong

Solutions:

Check the sealing of rubber plate, reinstall the cover plate

Check the installation of filling valve, valve core action and spring tension.

Adjust feed parameters of Y-axis

The length & angle deviation of work pieces changes heavily

Reasons:

Inertial parameter setting of press brake is improper

Plate material

Solutions:

Readjust the inertial parameters

Check the plate material

Multi-bends, accumulated error will be too large

Reasons:

Multi-bends, accumulated error is very large

Unreasonable bending order

Solutions:

Accurately adjust each bend precision, strive to control the angle within negative error, size as precise as possible

Adjust the bending order when possible

Automatically calculated pressure by system is larger than die resistance

Reasons:

Bottom die selection is unreasonable when programming

Resistance setting of die is improper

Bending way is wrong when programming

Constant parameters have been amended, such as material parameter、unit and so on

Solutions:

Die selection is subject to the relationship between plate thickness and bottom die opening.

Properly setting the die resistance of press brake

Check developed programs

verify the constant parameters of machine

System calculation is very slow even crash when programming large radius bending

Reasons;

Pre-set X valve exceeds the X-axis Max. value when programming

Solutions:

Check the developed programs

Oil temp is too high

Reasons:

Some faults with hydraulic parts, such as filter cartridge blocked, oil contamination or deterioration

Long time high-pressure work

Solutions:

Check the filter cartridge, oil, replace if necessary

Check the reasons for long time high-pressure work, work demand, or other reason

The angle of work piece is not precise

Reasons:

If the error is too large, perhaps the programming not right, or the slider have became loose, or grating rule have broken down, etc

A bit of error is allowable, which can be adjust on the controller, if it become reliable after amending, it is normal.

Angle is not reliable, constantly change, perhaps slider become loose, grating ruler fault, or material quality etc

Solutions:

Check the work procedure, mainly check whether die, material, thickness, plate length, bending way is consist with actual operation, the slider connection and grating ruler connection have become loose or not.

A bit of error is allowable, which can be caused by many reasons, such as: the difference between the programming thickness and actual thickness of plate, plate evenness, die wear, operation method and so on.

Check the repositioning accuracy of Y-axis, check whether the slider connection, grating connection are proper, if OK, it is likely related to the material

The dimension of work pieces is not right

Reasons:

Size is not reliable, constant change, may be related to the power, servo drive, servo motor encoder and related cable, controller, screw rod mechanical connection, timing belt (Pulley) etc.

Dimension deviation, but reliable, generally related to beam parallelism of back gauge, linearity, stopper parallelism, verticality.

Positioning through bending edge, if the bending angle is larger than 90°, the size will be small

Solutions:

Check the repositioning accuracy if back gauge shaft, generally less than 0.02mm, if the difference is too large, individually troubleshoot the reasons, if the reasons caused by servo drive, servo motor encoder or controller, it’s better to be solved by manufacturer

First, check the beam parallelism, linearity, then check the stopping finger parallelism and verticality

 

If adopting bending edge positioning way, the bending degree shall less than 90°

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