Solutions for Sudden Load Loss in Servo Press Systems

Engineering Measures to Improve Safety and System Stability

Sudden load loss is a common but potentially harmful condition in servo press operation. If not properly controlled, it can cause hydraulic shock, excessive vibration, component fatigue, and long-term damage to the press structure and hydraulic system. This article explains the engineering causes of sudden load loss and presents practical solutions to reduce its impact and improve system reliability.

1. Engineering Principle Behind Sudden Load Loss

In a hydraulic or servo-driven press system, the oil column height inside the hydraulic cylinder is inversely related to the elastic potential energy stored in the system.

When a servo press suddenly loses its working load:

• Stored hydraulic energy is released rapidly

• Piston acceleration increases sharply

• System pressure drops uncontrollably

• Mechanical shock and vibration occur

Therefore, reducing the effective oil height and controlling energy release are key engineering strategies to mitigate sudden load loss.

2. Structural Methods to Reduce Impact Energy

2.1 Adjustable Cushion Block Design

By adding or adjusting a cushion block between the worktable and upper die, the effective stroke of the ram or bearing beam can be shifted.
This reduces the oil column height in the cylinder, limiting the elastic energy stored during pressing and lowering the impact energy released during load loss.

2.2 Movable Backing Plate Between Piston Rod and Ram

Another effective solution is installing a movable backing plate between the piston rod and the bearing beam.

• During downward movement, the piston rod and ram move together normally

• After pressurization, the backing plate delays direct force transmission

• Hydraulic energy is released more gradually

• Sudden kinetic energy discharge is effectively suppressed

This design helps delay and soften load loss, protecting both mechanical and hydraulic components.

3. Hydraulic Circuit Pressure Relief Design

Sudden load loss can also be managed through controlled pressure relief paths in the hydraulic circuit:

• High-pressure oil is discharged safely to the low-pressure side

• Pressure peaks are reduced instantly

• Hydraulic shock is minimized

⚠️ This method requires strict maintenance discipline, as valve sensitivity and cleanliness directly affect system safety.

4. Pre-Operation Inspection to Prevent Load Loss Risks

To reduce the probability and severity of sudden load loss, operators should perform the following checks before operation:

1. Oil level inspection
   Ensure the hydraulic oil level reaches the specified range on the level gauge.

2. Electrical safety check
   Verify grounding, fuses, and power protection devices.

3. Stroke and load adjustment
   Adjust screw rod height and working range according to sample size and process requirements.

4. Sample surface inspection
   Replace damaged or defective samples that may affect load stability.

5. Instrument zero calibration
   Confirm gauges and sensors return to zero before testing.

6. Low-speed startup
   Begin operation at slow speed to ensure smooth pressure build-up.

7. Controlled loading process
   Increase pressure gradually until the required load or failure condition is reached.

8. Post-operation reset
   Remove damaged samples and reset indicators before the next cycle.

5. Vibration Damping as an Auxiliary Protection Measure

Installing shock-absorbing rubber pads under the servo press can further reduce structural damage:

• Absorbs vibration during sudden energy release

• Converts kinetic energy into heat

• Reduces transmission of shock to the foundation

This is a simple but effective supplementary protection method, especially for high-tonnage servo presses.

Conclusion

Sudden load loss in servo press systems is a system-level engineering problem, not a single-component issue.
By combining:

• Structural optimization

• Hydraulic pressure relief design

• Correct operating procedures

• Vibration damping measures

manufacturers can significantly reduce equipment damage, extend service life, and improve operational safety.