52/53 series double-row angular contact ball bearings are widely used in mechanical equipment because they can bear radial and axial loads at the same time, have high rigidity and occupy small space. However, to give full play to their performance, the correct selection and application of preload is a crucial link. Preload not only affects the running accuracy of the bearing, but also determines its service life and the stability of the equipment. The following will discuss the role of preload, influencing factors and selection methods.
1. The role of preload
Preload is the force that keeps the rolling elements inside the bearing in proper contact with the raceway by applying a certain axial load. Reasonable preload is of great significance to the performance of 52/53 series bearings:
Improve running accuracy: preload eliminates the internal clearance of the bearing and increases rigidity, thereby improving the running accuracy of the equipment, especially in mechanical equipment that requires high-precision positioning.
Enhance load-bearing capacity: Through preload adjustment, the bearing can share the load more evenly and avoid early failure due to excessive local load.
Suppress vibration and noise: Appropriate preload can reduce the relative movement between the rolling elements and the raceway, and reduce vibration and noise during equipment operation.
Prevent rotation slip: For high-speed equipment, appropriate preload can avoid rolling element slip and ensure the normal operation of the bearing.
2. Main factors affecting preload selection
Selecting the appropriate preload requires comprehensive consideration of the equipment's working conditions, bearing structure and operating environment. The following are several key factors:
Load conditions:
Light load conditions: Suitable for lower preload to reduce friction and heat.
Heavy load conditions: Requires higher preload to improve rigidity and prevent bearing deformation.
Speed requirements:
High-speed rotating equipment needs to moderately reduce preload to reduce friction and heat; low-speed or intermittent equipment can appropriately increase preload to enhance positioning.
Bearing pairing method:
Face-to-face installation (DB type): Suitable for bearing large radial loads and tilting moments, but the preload cannot be too high to avoid increasing friction.
Back-to-back installation (DF type): High rigidity, suitable for scenarios requiring high axial positioning accuracy.
Tandem installation (DT type): The preload needs to match other bearings to balance the load of the overall system.
Temperature influence:
Temperature rise will cause the bearing to expand, thereby changing the preload size. Temperature compensation measures need to be considered to ensure the stability of the preload.
Materials and lubrication conditions:
Bearings made of different materials have different tolerances to preload, and the lubrication state (such as grease lubrication or oil lubrication) will also affect friction and heat generation, thereby determining the range of the preload.
3. Selection and application of preload
The methods for reasonable selection and application of preload mainly include the following:
Calculation method to select preload:
According to the load, speed and service life requirements of the equipment, the recommended preload value is calculated through the bearing design formula. The formula needs to consider parameters such as the number of rolling elements, contact angle, and load distribution.
Adjustment method:
Mechanical adjustment: Axial force is applied through nuts, washers or spring structures to achieve preload. This method is suitable for multiple adjustments and ample installation space.
Temperature difference adjustment: The thermal expansion and cold contraction characteristics of the bearing during installation are used to control the assembly temperature difference to achieve the setting of preload.
Preload measurement and verification:
After applying the preload, it is necessary to verify it through measuring tools. Common methods include:
Clearance measurement method: Use a feeler gauge or laser rangefinder to measure whether the bearing clearance meets the design requirements.
Torque measurement method: Indirectly confirm the size of the preload by measuring the starting or running torque required for the bearing to rotate.
Axial displacement method: Observe whether the axial displacement after preload meets the design standard.
4. Precautions and optimization suggestions
When applying and adjusting the preload of 52/53 series bearings, the following matters should also be noted:
Avoid excessive preload: Excessive preload may cause excessive contact pressure between the rolling element and the raceway, increase friction and heat, and accelerate bearing wear.
Dynamic adjustment capability: For equipment with large load and temperature changes, consider introducing elastic elements (such as disc springs) to achieve dynamic adjustment.
Lubrication optimization: Ensure good lubrication conditions to reduce the additional friction heat caused by preload.
Regular inspection: During operation, it is necessary to regularly monitor the vibration, noise and temperature rise of the bearing, and adjust the preload in time to extend the bearing life.
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