Single-column hydraulic press common troubleshooting: solutions for pressure retention failure and slide creep

1.Troubleshooting and solutions to pressure holding failure of single-column hydraulic press

Fault phenomenon

The pressure gauge pointer slowly drops after pressurization (>5MPa/min)

The slider sinks significantly during the pressure holding stage (>0.5mm/min)

The workpiece forming size is unstable

Fault cause and treatment steps

(1) Hydraulic system leakage

Troubleshooting points:

Main cylinder seal ring wear: disassemble the cylinder and check whether the Yx-shaped seal ring lip is cracked (it is recommended to replace the entire group when replacing)

Control valve internal leakage:

Test cartridge valve/relief valve: Under pressure holding state, the temperature of the oil return pipe of the valve body rises abnormally (>50℃), indicating internal leakage

Solution: Grind the valve core or replace the valve group (pay attention to the cleanliness of NAS 8 level)

Leakage of pipe joints: Wrap the joints with a paper towel to observe the oil stains (If the torque is insufficient, re-tighten to the standard value)

(2) Hydraulic oil contamination

Testing standard:

Oil cleanliness > NAS level 10 → Replace the filter element and filter the oil

Water content > 0.1% → Dehydrate or change the oil (anti-wear hydraulic oil VG46 is recommended)

(3) Pressure relay failure

Calibration method:

Use a pressure calibrator to test the relay action point deviation (allowable error ±0.3MPa)

Adjust the micro switch or replace the relay

2.Slider creep problem troubleshooting and solution

Fault phenomenon

The slider vibrates when it moves downward

Crawling is obvious when the speed is lower than 10mm/s

Vibration marks appear on the workpiece surface

Causes of the fault and treatment steps

(1) Poor lubrication of the guide rail

Solution:

Check the guide rail oil film thickness (should be ≥0.05mm)

Use molybdenum disulfide lithium-based grease (suitable for low speed and heavy load)

Adjust the guide rail clearance (feeler gauge detection, lateral clearance ≤0.1mm)

(2) Hydraulic system air intake

Evacuation operation:

Open the exhaust valve at the highest point of the system (or repeatedly run the slider through the full stroke 10 times)

Observe the disappearance of bubbles in the oil tank return port (replenish oil to the upper limit of the liquid level if necessary)

(3) Oil pump flow fluctuation

Detection method:

Connect the flow meter to test the pump output stability (fluctuation > 5% requires maintenance)

Check the coupling alignment error (radial < 0.1mm, axial < 0.05mm)

(4) Proportional valve response delay

Optimization measures:

Cleaning the valve core (do not use cotton yarn, use an ultrasonic cleaning machine)

Adjust PLC control parameters (such as PID gain value)

3. Emergency procedures for single-column hydraulic presses

• Immediate shutdown: Avoid hydraulic shock damage to seals caused by leaks
• Pressure relief: Manually release the relief valve to release system pressure
• Fault location: Take photos to record the location of oil stains and abnormal vibrations