The design and assembly of crossed roller bearings are key links to ensure their performance, life and stable operation of the entire mechanical system, and are also key links to ensure their normal operation and service life.
Structural Design
The structural design of crossed roller bearings is the basis of their performance. The bearing's load capacity, running accuracy, friction and wear, and lubrication and sealing factors must be fully considered during design.
The cross arrangement of rollers, raceway shape, cage structure, etc. all need to be carefully calculated and optimized to ensure that the bearings can perform well under various working conditions.
Common types of crossed roller bearings include RB type (inner ring as a whole, outer ring split), RE type (inner ring split, outer ring as a whole), RU type (inner and outer ring as a whole, with mounting holes), RA type (inner ring as a whole, outer ring split, ultra-thin), etc. Each type has its specific application scenarios and advantages.
Material Selection
Material is one of the key factors that determine bearing performance. When selecting materials, it is necessary to consider its strength, hardness, wear resistance, corrosion resistance, and thermal stability.
Common materials include high carbon chromium bearing steel, stainless steel, ceramics, etc. Different materials have different performance characteristics and need to be selected according to the specific use environment and requirements of the bearing.
Heat treatment process
Heat treatment is an important means to improve the performance of bearing materials. Through heat treatment processes such as quenching, tempering, and carburizing, the material's organizational structure can be improved, and its strength, hardness, and wear resistance can be improved.
At the same time, heat treatment can also eliminate stress inside the material and improve the dimensional stability and fatigue resistance of the bearing.
Machining accuracy
The machining accuracy of the cross roller bearing has a direct impact on its performance. During the manufacturing process, high-precision processing equipment and processes are required to ensure the dimensional accuracy and shape accuracy of the inner and outer rings, rollers, and cages of the bearing.
At the same time, it is also necessary to strictly control the thermal deformation and residual stress during the processing process to ensure the accuracy and stability of the bearing.
Surface treatment
Surface treatment is an important part of improving bearing performance and service life. Through surface treatment processes such as grinding, polishing, and super finishing, the roughness of the bearing surface can be reduced, and its finish and wear resistance can be improved.
In addition, coating technology, such as hard chrome plating and ceramic spraying, can be used to further enhance the hardness and corrosion resistance of the bearing surface.
Preparation work
Before starting assembly, you need to make adequate preparations, including preparing the required tools and materials, checking the cleanliness of the bearing and housing, and applying lubricants.
Assembly steps
Assemble the rings and rolling elements of the cross roller bearing together to ensure free rotation and uniform clearance between the rolling elements.
Use appropriate tools and methods to install the bearing on the housing, and pay attention to maintaining moderate force to avoid damaging the bearing and the mating surface.
During the assembly process, it is necessary to strictly control the clearance between the roller and the inner and outer rings to ensure that the clearance and preload of the bearing are moderate.
Inspection and debugging after assembly
After the assembly is completed, a series of inspections and debugging work is required, including checking the rotation flexibility of the bearing, the tight fit of the mating surface, the adjustment of the preload, and the normal operation of the lubrication system.
Through the trial run test, observe whether the operating status of the bearing is normal. If any problems are found, they should be handled and adjusted in time.
Carrying capacity
Determine the rated load capacity of the cross roller bearing according to the actual working conditions and load requirements. This requires consideration of factors such as radial load, axial load and rectangular load, and determine the appropriate parameters through relevant engineering calculation methods.
The stiffness and precision of the cross roller bearing directly affect the stability and accuracy of its operation. When designing, it is necessary to select appropriate materials and geometric structures to improve the stiffness and precision of the bearing, and by optimizing the internal structure of the bearing and the contact angle and other parameters, reduce the friction and clearance of the kinematic pair and improve the motion accuracy.
Lubrication and sealing
Good lubrication is a key factor in ensuring the long-term and stable operation of the bearing. When designing, it is necessary to consider the selection of grease and the design of the lubrication oil circuit to ensure that the bearing has a good lubrication state during operation.
The selection of seals is also crucial to prevent dust, moisture and other contaminants from entering the bearing and affecting the performance and life of the bearing.
Assembly and adjustment
When designing, it is necessary to consider the tolerance matching requirements and the adjustability of the bearing during the assembly process, so as to achieve the appropriate installation clearance and preload during the assembly and adjustment process.
The tolerance of the bearing and the selection of the shaft control room also need to be carefully controlled to ensure that the bearing and the shaft fit well and avoid excessive extrusion or deformation of the bearing.
Accuracy grade
The accuracy grade of the cross roller bearing has an important influence on its performance and life. When designing, the appropriate accuracy grade should be selected according to the application requirements to ensure that the bearing has high rotation accuracy and low friction resistance.
Life requirements
Life is one of the important indicators to measure the performance of the cross roller bearing. When designing, the required life requirements should be determined according to the application scenario in order to select the appropriate material and heat treatment process.
Cleaning and inspection
Before assembly, the bearing parts must be carefully cleaned to ensure that their surfaces are clean and oil-free. At the same time, check whether the parts have defects or damage, and replace the problematic parts in time.
Grease application
During the assembly process, it is necessary to apply an appropriate amount of grease inside and outside the bearing. The selection of grease should meet the design requirements and ensure that it can provide good lubrication and protection during the operation of the bearing.
Installation order and method
Place the cleaned and lubricated bearing on the shaft or seat, and perform the correct installation order and assembly method according to the design requirements. Ensure that the bearings and related parts fit well, and pay attention to avoid excessive extrusion or deformation of the bearings.
Adjustment of preload and clearance
According to the design requirements, adjust the bearings and control the preload. By adjusting the nuts, gaskets or using special adjustment tools, the bearings can reach the appropriate installation clearance and preload to ensure their normal operation.
For high-load and high-speed cross tapered roller bearings, the effect of temperature rise on axial clearance should also be considered when adjusting the clearance, and the clearance reduction caused by temperature rise should be estimated.
Installation of seals
Install seals according to design requirements to ensure that the interior of the bearing is protected from dust, moisture and other contaminants. At the same time, for bearings that are stored or transported for a long time, corresponding protective measures should be taken to avoid surface corrosion and damage.
Precautions during installation
Cross roller bearings are high-precision products. During the assembly process, special attention should be paid to avoid using excessive force or improper assembly methods to avoid damaging the bearings.
During the installation process, attention should also be paid to maintaining the dynamic balance of the bearings to avoid the generation of impurities such as iron filings that may damage the bearings.
In summary, the design and assembly of crossed roller bearings need to consider multiple factors such as load capacity, lubrication and sealing, assembly and adjustment, accuracy level, life requirements, etc. By comprehensively considering these factors, it can be ensured that the performance and life of the crossed roller bearings meet the design requirements.
