Causes of High Vibration in High-Speed Paper Machine Drive Shafts

Balance Testing Before Delivery

Before a high-speed paper machine’s drive shaft (universal joint shaft) is delivered for use, it must undergo dynamic balancing testing. The unbalanced amount is calculated based on the weight of the shaft, its operating speed, and the required balance grade. The dynamic balancing test equipment simulates the actual operating speed to measure the imbalance at both ends.

The imbalance is then reduced to meet the design specifications. For example, the universal joint shaft in the press section of the machine typically operates at 1200 RPM, and a balance grade of G6.3 is selected. After the dynamic balancing test, the vibration during actual operation should remain within the allowable range.

Methods of Dynamic Balancing

There are two primary methods for balancing the universal joint shaft: adding weight and removing weight.

• Adding Weight: This is the most common method, particularly for paper machine universal joint shafts that weigh more than 100 kg. Weight is added by welding counterweights to the outer diameter of the shaft’s fork to achieve balance. For heavy shafts, weight removal is more difficult.
• Removing Weight: For lighter universal joint shafts (weighing less than 10 kg), weight removal is typically preferred as it is easier to manage.

Regular Maintenance is Crucial

We recommend performing regular maintenance on the high-speed paper machine’s universal joint shaft. This includes daily lubrication of the universal joint bearings and spline parts with lithium grease (Grade 3), ensuring the lubrication system operates smoothly.

Every three months, it is advised to send the shaft back to the manufacturer for maintenance and dynamic balancing tests to ensure continuous operation of the equipment.

Conclusion

If significant vibration is detected in the paper machine’s universal joint shaft, the machine should not continue operating with the fault. Continued operation could lead to greater damage. Maintenance and care should be carried out by a qualified manufacturer. While dynamic balancing can address some imbalance issues, the most important factor is ensuring that all parts of the universal joint shaft—such as machining precision and assembly accuracy—are well controlled. A properly manufactured and assembled shaft, combined with thorough dynamic balancing, will have better balance and a longer lifespan. Simply relying on dynamic balancing to address imbalances when the shaft itself is poorly made will likely lead to unsatisfactory results.