The installation quality of sliding bearings is directly related to the operation stability and service life of the equipment. Improper operation can easily cause vibration, overheating and even premature aging. In installation process, it should be strictly controlled from four dimensions: cleanliness, cooperation accuracy, installation method and initial lubrication state. The following are the main preventive measures and practical principles:
I. Preparation for installation: cleaning and inspection
- Thoroughly clean parts
- Bearing cleaning: Wipe the inner ring, outer ring, runway and cage of bearings with a special cleaning agent or non-corrosive solvent to remove rust oil, metal shavings and other impurities and prevent particles from becoming embedded in the contact surface causing wear and tear.
- Journal processing: Check journal surface for indentations, scratches or rust. Use greasestone or fine sandpaper to make sure there are no sharp corners or burrs to avoid damaging bearings during installation.
- Bearing housing cleaning: cleaning the inner and oil holes of the bearing housing to ensure that there are no oil stain, iron filings or burrs. Check whether the surface roughness the inner hole meets the requirements and avoid uneven clearance due to surface roughness.
- Check key parameters
- Installation tolerances: Identify the type of tolerances (e.g. interference tolerances, clearance fit tolerances) between the bearing and the shaft neck and bearing housing, and ensure that the actual dimensions are within the tolerance range to avoid breaking due to insufficient interference resulting in loosening or excessive interference.
- Perpendicularity and coaxial degree: Perpendicularity and coaxial degree of bearing bearing housing neck are checked using dial indicator or laser alignment instrument to ensure accuracy of mounting reference surfaces and prevent uneven load handling.
- Bearing clearance: select suitable clearance grade (e.g. C2, C3, C4) according to working conditions. Before installation, it is necessary to verify that the gap meets the design requirements and avoid abnormal operation due to the gap.
II. Installation Method: selected according to working conditions.
- Cold installation method (suitable for small interference and bearing size)
Points for action
Apply grease evenly to the inner ring of the bearing and cover the raceway with thickness to reduce installation resistance.
Use a copper rod or special pressure sleeve to slowly press the bearing into the shaft neck. The direction of pressure should be consistent with the axis line to avoid tilting or local forces.
Taboo
It is strictly forbidden to hit the bearing inner or outer ring directly, otherwise it may cause the the raceway deformation or damage the cage.
After cold installation, the bearing should be checked to ensure that the bearing is installed correctly and that the bearing is not fully bonded to the shaft neck due to insufficient pressure.
2. Thermal packing method (suitable for large interference matching and bearing size)
Points for action
Heat the bearing to an appropriate temperature (usually lower than the the tempering temperature of the material), inflate the inner ring, and then insert the shaft neck. Heating options include oil bath, induction heating or oven heating. It is necessary to ensure temperature uniformity.
After heating, it is necessary to install quickly in order to avoid interference and failure due to temperature drop, and to prevent the bearings from contracting too much after cooling.
Taboo
The heating temperature shall not exceed the allowable value of bearing material, otherwise the performance of bearing material may be reduced.
Direct heating of bearings by open fire is strictly prohibited to prevent local overheating and cracking.
3. Hydraulic installation method (Suitable for High Precision and Heavy Load)
Points for action
Apply hydraulic oil to the inner bore and the surface of the shaft neck, install a special hydraulic sleeve, then pressurize the bearing with a hydraulic pump to inflate the bearing evenly and insert the shaft neck.
During installation, pressure and expansion volume need to be monitored in real time to ensure that the operation is controlled.
Taboo
Hydraulic system should be kept clean to prevent impurities from entering the oil circuit, causing abnormal pressure.
After installation, bearing clearance and pretensioning forces need to be checked to prevent the bearing from being over-compressed due to excessive pressure.
III. Inspection and Commissioning after installation
Clearance verification
After installation, the radial and axial clearances of the bearing needs to be inspected to ensure that it meets the design requirements. If the clearance exceeds tolerance, the thickness of the bearing housing gasket needs to be adjusted or reinstalled.
The method can be selected by a feeler gauge measurement or special clearance meter. In the course of use, external force interference should be avoided to prevent measurement errors.
Lubrication system debugging
Smooth oil flow: start the lubricating oil pump, check whether the oil oil pipes, oil holes is blocked, oil pressure is stable, ensure that the lubricating oil evenly covers the bearing contact surface.
Initial lubrication: Turn the lubricant several times manually to observe if the lubricant is distributed sufficiently to avoid dry friction leading to early wear.
Vibration and temperature monitoring
After installation is complete, short-term airlift operations are required. The vibration value of bearing is measured by vibration analyzer to ensure that the bearing has no abnormal vibration.
During the initial operation, the temperature of the bearing should be regularly recorded, the temperature rise rate and stability of the bearing should be observed to prevent overheating due to poor lubrication or installation deviation.