Hydraulic Press Brake Troubleshooting: The Ultimate Guide to Fix Common Problems
Francis Pan
1. Introduction
Hydraulic press brake is very important in the metal processing industry, it is widely used in the bending and forming of various parts, because its work efficiency is higher than that of general press brakes, so many enterprises need to use press brakes for production.
However, due to improper storage or long service life, some failures may often occur. These failures not only cause production to stagnate but can also affect productivity and potentially even have safety issues. Therefore, it is very important to troubleshoot the hydraulic press brake.
In this article, I will help users understand the common faults of hydraulic press brakes, and according to these common faults, make corresponding troubleshoots. So let me take you into this guide to start understanding and 阿 hydraulic press brakes!
2. Common user search questions (FAQs) and corresponding chapters
2.1 Machine won’t start?
2.1.1 Possible causes
Power issues
First of all, check whether the main power supply is connected, and secondly, check whether the power socket is damaged or poor contact, and the fuse in the electrical cabinet may be blown or tripped, or the power supply used may be unstable, resulting in too high or too low voltage, and these power supply problems will affect the machine to not start.
Emergency stop activation
The emergency stop button is mainly to ensure the safety of the operation, if the emergency stop button is pressed, this button will be activated, then the main control line will be cut off, and the emergency stop line will be loose and then fail, resulting in the machine stopping and unable to start.
Failure of the safety interlock system
The safety interlock system is mainly to ensure the safety of equipment and personnel during operation. Therefore, hydraulic press brakes are usually equipped with multiple safety interlocks, these interlock damages may include relay damage, alarm failure of safety module alarm, damage to protective doors, etc., if one of the safety chains is damaged, the machine cannot start.
Control failure
The main reasons for the failure are that the controller power supply is not connected, which will lead to an internal short circuit, and the control panel or relay may fail, and the operation instructions will not be received, which will cause the machine to fail to start.
2.1.2 Troubleshooting Steps
Check the power supply
First, check whether the power outlets of these are plugged in, check whether the power cord is damaged, and then use a multimeter to detect the voltage to ensure that the voltage is within the normal range. Also check whether the fuse is loose, whether the circuit of the electrical cabinet is loose or damaged, and if there is any abnormality, replace the fuse in time or eliminate the hidden danger of the line.
Emergency stop activation
Check all the emergency stop buttons first, and if the buttons are pressed, you need to rotate them to reset them in turn to make sure the buttons are in the released state. Then use a multimeter to measure whether the emergency stop line is broken, and if it is, it needs to be repaired.
Failure of the safety interlock system
First of all, you need to check all the safety doors and guards to see if they are closed normally, and then check the safety interlock system of the hydraulic press brake, including the lines of some parts such as gratings and door locks.
Electronic control system maintenance
First of all, you need to check whether the indicators on the controller are on normally, if you find an error, you need to turn off the power and then restart the operation panel, and then diagnose it through the equipment manual, if there is still a problem, you need to consider replacing the components or contact a technician.
2.2 Why is there no pressure in the hydraulic system? Machine startup unresponsive?
2.2.1 Possible causes
The solenoid relief valve coil is not energized or undervolted
It is possible that the solenoid valve is not energized, or the voltage is not reached, and the solenoid controlling the relief valve cannot be suctioned, so the oil circuit will continue to flow back, and the valve will not be opened, resulting in no pressure output in the system. It is also possible that the line is burned out, or the voltage does not meet the requirements.
The relief valve spool or main valve spool is stuck or blocked
If the relief valve spool of the press brake is stuck or clogged with contaminants, it will cause the hydraulic oil to not circulate inside the machine, resulting in the hydraulic oil not establishing pressure properly.
The three-phase electrical wiring is reversed, causing the pump to reverse
If the three-phase power supply has an error in wiring, it may cause the motor to reverse, and the oil pump cannot absorb hydraulic oil to establish pressure, resulting in no hydraulic action in the operation of the machine, which in turn causes the oil pump to not work normally.
Faulty oil pump or wrong direction
If the oil pump of the hydraulic press brake is found to be damaged, or the direction of the hydraulic oil inlet and outlet is found to be wrong, it will lead to problems with the flow of hydraulic oil.
pressure gauge damage, etc
If you already know that the press brake has the pressure of the hydraulic system, but the pressure gauge is not displayed, or it may be that the pressure gauge is leaking, both of these situations indicate that the pressure gauge itself is faulty and cannot correctly know the pressure of the hydraulic system.
2.2.2 Solution
First, check the voltage through a multimeter to determine whether the power supply of the solenoid valve is properly connected, and if there is a cassette in the spool, it is necessary to remove the dirt. If there is a problem with the oil pump status, it will need to be disassembled, cleaned and inspected, and the pressure gauge will need to be replaced to ensure that the displayed system pressure is working properly.
2.3 When pressing down quickly or switching speeds, the slider has a long pause or delay?
2.3.1 Cause analysis
The oil level of the fuel tank is too low, and the self-priming pipeline sucks in air
Due to the lack of oil in the hydraulic oil, the oil pump will not be able to absorb effectively, the hydraulic oil will be incompletely absorbed, and then the system will enter the air, so that the pressure is established relatively slowly, thus affecting the pressure of the hydraulic system and the flow of oil.
The rapid drop is too fast to refuel in time
If the downward speed of the slider far exceeds the oil replenishment capacity of the oil pump, the hydraulic oil will not be replenished, forming a vacuum, and then the hydraulic oil pressure will drop, and the servo system will have a problem with reversal, resulting in the hydraulic press brake stopping.
The oil filling valve is blocked or not fully opened
Because the oil filling valve or check valve is blocked due to contaminants, or is stuck, it is also possible that the oil filling valve is not fully opened, which will prevent the hydraulic oil from entering the hydraulic system, so that the hydraulic oil cannot be replenished in time, and then the slider will move slowly, which will cause the press brake to slow down, and finally stop.
Improper CNC parameter setting leads to delays
If the parameters on the CNC controller are problematic, it will affect the response speed of the hydraulic system, which will lead to program delays.
2.3.2 Solution
First of all, the oil level in the fuel tank is not within the normal range, so you need to replenish the hydraulic oil. Secondly, if the charging valve is found to be blocked, the valve needs to be cleaned in time. Then due to the program delay caused by the unreasonable CNC parameters, it is necessary to restore the factory settings if necessary and adjust the parameters according to the actual situation.
2.4 The slider in manual mode cannot be pressed down, and the bending force is insufficient?
2.4.1 Possible cause analysis
The four-way reversing valve or oil filling valve is stuck and does not work
Because the reversing valve spool is polluted, worn, or stuck by other impurities, the valve cannot switch the oil circuit, which will cause the oil circuit to be blocked, and then the elasticity of the valve core will also be weakened, and the slider cannot be pressed down, so that the valve loses the function of opening and closing.
The valve is not energized or sticky
When the solenoid valve is not energized, the indicator light is not on, or there is a fault inside the solenoid valve, it will cause the valve to not be able to open and receive instructions. If used for a long time, the solenoid valve may eventually lead to stickiness and stop operation due to coil damage, solenoid valve wear, lack of lubricating oil, etc.
The upper chamber of the slider is not isolated, and the pressure cannot be established
Due to the lack of sealing of the hydraulic pressure in the upper cavity, the hydraulic oil leakage will cause the oil filling valve to not be able to work normally, and the upper cavity of the slider cannot be completely closed, and the system will always be in a state of less pressure or hydraulic oil backflow, so it will cause the hydraulic pressure in the lower cavity to not be able to store enough pressure, so that the slider moves down.
2.4.2 Solution
First of all, you need to use a multimeter to check the resistance of the solenoid valve coil, and regularly clean and replace the valve core, and then check the oil-filled valve, whether it is in good condition, and the substances of the valve core need to be cleaned in time, and finally check whether the slider can have enough pressure when pressing down, and its pressure should be greater than the specified threshold.
2.5 The slider rises too slowly, or the return pressure is abnormally high?
2.5.1 Possible cause analysis
The oil filling valve is not open
If the oil filling valve is not fully opened, the hydraulic oil cannot be replenished in time, or the pressure is released, which may cause the hydraulic oil to not enter the upper cavity of the slider smoothly, then the hydraulic oil in the upper cavity of the slider cannot be replenished or flow back into the oil tank, and the pressure in the upper chamber is difficult to release, so the speed of the slider rising is relatively slow.
The upper chamber cannot relieve pressure
Due to the large amount of dirt in the pipeline of the oil-filled valve, the pipeline is deformed, which will lead to the hydraulic oil cannot be discharged in time, and in the process of the slider rising or returning, it is easy to have excessive hydraulic pressure, which eventually leads to the pressure relief valve not being able to work normally.
2.5.2 Solution
First of all, make sure that the oil filling valve is fully open, to determine whether the valve is under the control signal, normal response, and check the hydraulic oil, whether it is smooth and not blocked, check whether the oil is sufficient, and check the router, whether it needs to be cleaned and replaced, and then through the pressure gauge, to observe the pressure when the slider rises, to ensure that it is within the numerical range of pressure, if the pressure is too high, you need to check the oil pipe, whether there is a leak or blockage.
2.6 Is the slider sound abnormal when running? Is there a banging sound or is it not vertical?
2.6.1 Possible causes
The guide rail is worn and the slider is tilted out of parallel
Due to the long running time of the press brake, it will cause the guide rail to wear, which will lead to the gap between the guide rail and the slider, so that the position of the slider will deviate, so abnormal sound will occur when running. If the slider is not aligned, it will tilt, which will cause uneven force in the bend, resulting in noise.
The slide impact sound can be a blocked spool, a blocked oil passage, or a phase error
Due to the presence of sediment in the oil channel in the tank, blockage will occur, so the flow speed of hydraulic oil will slow down. Then the valve core switching time of the hydraulic valve is too early or too late, which will cause the machine to run poorly and then cause abnormal sounds.
2.6.2 Solution
First of all, check whether the guide rails are parallel, if not, make appropriate adjustments, secondly, confirm the installation of the slider, whether it is aligned and fixed, and then check all the bolts, and whether the connectors are tightened, and finally check the working status of the valve core, and whether the oil circuit is smooth, if there is a blockage, it needs to be cleaned in time.
2.7 Poor bending accuracy? Inconsistent two ends and inaccurate angles?
2.7.1 Analysis of possible causes
Tool is worn or misaligned
Due to the long service life of the press brake tool, it will cause wear of the tool, the gap between the upper die and the lower die will change, and the contact surface will be incomplete, thus affecting the angle of bending. It may also be because the upper and lower membranes are not aligned according to the center, and the gaps at the two ends are different, which will lead to uneven force during bending.
Back gauge ruler positioning deviation
The press brake back gauge ruler is mainly used for bending positioning, if there is looseness in the process of motor transmission, or there is dirt on the guide rail, it will lead to errors in the accuracy of bending.
The slider adjustment offset is inconsistent
Due to the unbalanced placement of the two ends of the slide, it will lead to the actual depth of the downward pressure is different, and may deviate from the normal position, so if the back-and-forth movement continues, the gap of the slider will become larger and larger, due to long-term wear, and not compensated in time, which will eventually lead to different angles in the bending process.
2.7.2 Solution
First of all, it is necessary to regularly check the wear of the tool, and then use special measuring tools to measure the accuracy of the tool, and secondly, check the hydraulic system, whether there is a leakage or blockage, if there is a problem, it is necessary to replace the hydraulic oil, and then reposition it according to the standard angle gage, so as to ensure the accuracy and consistency of the processing, and finally check the running trajectory of the slider, and regularly calibrate the sensor.
2.8 Oil pump overheating?
2.8.1 Analysis of possible causes
Insufficient oil
If the hydraulic oil of the press brake is not enough, it will cause the oil pump to be unable to be utilized, which may cause local high temperatures.
Contaminated
Usually if impurities or water are mixed in the hydraulic oil, it may cause the viscosity of the oil to become low and the cooling to weaken, resulting in problems with the oil pump.
Over-operation
Due to the excessive use of the oil pump for a long time, the hydraulic oil heats up quickly and cannot dissipate heat.
Cooling system failure
If it is not equipped with a cooling system such as water cooling and radiator, it will cause the cooling system to become clogged, and the final heating effect will be poor.
2.8.2 Solution
First of all, check whether the oil level is within the specified range, if not, it is necessary to replenish and replace the oil in time, and then sample the hydraulic oil, observe the color, viscosity and impurities of the oil, if pollution is found, it is necessary to change the oil and clean the oil tank, and finally check whether the cooling system is blocked, whether the radiator and water tank are well ventilated, and also need to check the coolant level, as well as the quality, to ensure that it can be replaced and replenished in time.
2.9 Hydraulic oil leak?
2.9.1 Possible causes
The seal ring is worn
Because the long-term use of the sealing ring will lead to the aging of the material and the elasticity will become low, there is no way to effectively prevent the leakage of oil.
Loose joints
Due to the relatively high working strength of the equipment, the thread may be loose.
2.9.2 Solution
If cooling is found to be blocked, cleaning is required. Then check whether the fuel level in the fuel tank is within the specified range and refill if necessary. Secondly, if the hydraulic oil is dirty, the oil needs to be replaced in time.
2.10 Abnormal noise of oil pump
2.10.1 Possible causes
Damaged pump shaft or impeller
Because the machine works for a long time, it may cause wear on the bearings and impellers, resulting in noise.
System air intake leads to cavitation
Because the oil pump sucks in air during operation, resulting in bubbles, the bubble rupture will cause louder noise.
Oil filter blockage, hydraulic fluid contamination or reduced viscosity
Because there may be impurities or moisture in the hydraulic oil, it will lead to reduced lubrication and the inability to form an effective mucous membrane, resulting in noise.
2.10.2 Solution
First of all, check the level of the oil tank of the hydraulic system to ensure that it is within the normal range, if the air is inhaled, it needs to be discharged to ensure that the oil pump can work smoothly, and secondly, the oil filter needs to be cleaned and replaced regularly, and then check the quality of the hydraulic oil to ensure that it is free of moisture, no impurities, and meets the standards.
2.11 Electrical system failure?
2.11.1 Analysis of possible causes
Loose and aging cables
Due to the long-term use of the machine, it will cause the cable to loosen and deteriorate, resulting in signal interruption.
Relay and limit switch failed
Due to the failure of the relay, the limit switch is damaged, which will cause the signal to not be received correctly.
Controller error or parameter error
Due to CNC/PLC program crashes or errors, the machine may not operate properly.
The control system is slow to respond, and the error needs to be reset or factory reset
If there is an error in the control system, the response will slow down, and then it will need to be restarted.
2.11.2 Solution
When noise occurs, the oil pump needs to be checked regularly to see if there are any leaks. It is also necessary to check whether the hydraulic system is within the normal range, and if the hydraulic oil has impurities or sucks in air, the hydraulic oil needs to be replaced in time.
3. Suggestions for troubleshooting processes
3.1 Preliminary inspection
Before all inspections or repairs, first make sure that the machine has been completely de-energized, whether the hydraulic system is still there, whether the press brake operator is safe, whether the tank level is higher than the minimum warning line, whether the oil temperature is between 20° and 60°, and whether the pressure gauge is working properly.
3.2 Symptom confirmation
First, observe and record the slider, including: If the slider does not respond, you need to check the power supply. If the slider is tilted, it is necessary to check that the tool, slide and rail are on a horizontal line. If you notice an abnormal sound on the slider, you need to check whether the mechanical structure is faulty.
3.3 Sub-system investigation
If the hydraulic system is checked, it is necessary to check whether the various valves are working normally, whether the hydraulic oil is within the standard range, and whether the filter is blocked. If you check the mechanical structure, you generally check the wear between the guide rails and sliders, and you also need to see if they are on a horizontal line.
3.4 Schedule regular maintenance
In order for the machine to be better used, it is best to inspect and maintain the equipment to avoid machine failure. Not only that, but regular inspections and replacement of worn tools are also required to reduce equipment maintenance costs.
4. How to do preventive maintenance? Maintenance intervals and operating specifications?
4.1 Cleaning and maintenance
First of all, it is necessary to add lubricating oil to each component to ensure that the system is not clogged, and it is also necessary to check the oil level regularly to ensure that the oil level is within a safe range.
4.2 Fluid replacement, spare parts management and personnel training
First of all, according to the manufacturer’s recommendations, it is necessary to regularly replace the hydraulic oil and filter to avoid deterioration of oil quality, and then regularly inventory the damaged parts, and ensure that these parts are in stock to ensure timely replacement in case of failure. Finally, it is necessary to regularly conduct technical training for the operators of the equipment so that they can know the fault and repair it in time, thereby reducing losses.
In this article, we have discussed some common press brake problems along with their solutions and know the daily maintenance of the equipment. If you need more information on this, please contact us. RAYMAX provides 24 hours free service, looking forward to hearing from you.
As a manufacturer of fiber laser cutting machines and press brakes, RAYMAX is committed to expanding its influence while also providing more, more professional, and more comprehensive knowledge of CNC machinery for friends in the metal processing industry. If you experience any unresolved issues or are interested in purchasing related machines, please feel free to contact us at any time. RAYMAX offers free technical support services 24 hours a day, 7 days a week! Looking forward to your letter ~~~
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