1. Basic methods of preload force control
Positioning preload:
Preload is achieved by adjusting the axial position of the inner and outer rings of the bearing or by using spacers and shims that have been adjusted in size.
The advantage is that the preload force is stable and suitable for scenarios with high rigidity requirements, but not suitable for situations where axial vibration needs to be prevented.
Constant pressure preload:
Preload is applied using elastic elements such as springs, wave washers or hydraulic systems.
The advantage is that the preload force can be adjusted as external conditions change, and is suitable for environments with high-speed rotation and large temperature changes.
2. Tips for adjusting preload force
Calculate preload force:
Calculate preload force based on factors such as bearing load, rigidity requirements, and temperature conditions, usually referring to the recommended values provided by the bearing manufacturer.
For angular contact ball bearings installed in pairs, the axial preload force can be set at 2%-5% of the rated static load of the bearing.
Measurement and adjustment:
Use a feeler gauge or dial indicator to measure the axial clearance and make adjustments.
Use a torque tester to check the rotational torque of the bearing under different preloads to ensure that the preload is appropriate.
Use vibration analysis to observe the operating status of the bearing. Excessive vibration may mean that the preload is too large or insufficient.
3. Precautions for preload control
Avoid excessive preload:
Excessive preload will cause abnormal heating of the bearing, increased friction torque, and reduced fatigue life.
Avoid too small preload:
Too small preload may cause vibration, noise or unstable positioning of the bearing during operation.
Control the installation force:
When installing the bearing, special tools should be used to apply force evenly to avoid direct knocking.
Preload can be applied more evenly by hydraulic method or hot installation method.
4. Application of preload in different bearing types
Angular contact ball bearings:
When the preload is large, the rigidity of the bearing can be improved, which is suitable for machine tool spindles and high-precision equipment.
Tapered roller bearings:
Usually preloaded by nut adjustment method, suitable for automobile hubs and heavy machinery.
Deep groove ball bearings:
Mostly used for low preload or no preload installation, suitable for motors, fans and household appliances.
