What should be noted for the installation and maintenance of roller bearings?
The installation quality and maintenance frequency of roller bearings directly determine their service life, especially in heavy load, low-speed, and dusty industrial conditions. It is necessary to focus on the three core aspects of assembly accuracy, cleaning and protection, and lubrication and maintenance.
1、 Installation precautions
Pre-installation preparation
Cleaning treatment: Oil stains, iron filings, dust and other impurities on the inner and outer rings, shaft necks and mounting holes of the bearing must be removed. They can be cleaned with anhydrous ethanol or kerosene, dried before assembly; It is strictly prohibited to touch the bearing raceway directly with dirty cloth or hands.
Dimensional verification: Check the fit tolerance between the journal and the inner ring of the bearing (usually transition fit H7/k6), and the fit tolerance between the installation seat hole and the outer ring of the bearing (clearance fit H7/h6), to avoid excessive interference causing bearing deformation or excessive clearance causing operational movement.
Tool selection: Priority should be given to using pressure sleeves and specialized installation fixtures to press the bearing into the journal by applying force through the inner ring end face; It is strictly prohibited to directly strike the outer ring or rolling elements of the bearing, otherwise it may cause damage to the raceway and breakage of the rolling elements.
Eccentric sleeve adjustment (for eccentric sleeve type roller bearings): During installation, rotate the eccentric sleeve to adjust the contact gap between the roller and the track (the gap should be controlled at 0.05-0.1mm). After adjustment, tighten the locking nut and install a locking washer to prevent the eccentric sleeve from loosening due to working condition vibration.
Key points of installation process
Coaxiality control: When multiple rollers are installed side by side, it is necessary to ensure that the axes of each roller are parallel and in the same plane, with a coaxiality error of ≤ 0.1mm/m, otherwise it will cause roller bias and local wear to intensify.
Axial positioning: For roller bearings with axial blocking edges, it is necessary to ensure that the blocking edges are tightly attached to the track flange surface without excessive clearance or jamming; The model without a blocking edge needs to be equipped with an axial limit ring to prevent axial movement of the bearing.
Avoid inclined installation: When assembling bearings, they should be kept horizontal or vertical. It is strictly prohibited to press them at an angle, otherwise it will cause the inner and outer rings to tilt, resulting in abnormal vibration and noise during operation.
Check after installation
Manually rotating the roller should be flexible, without any jamming or obvious abnormal noise;
Check the contact gap between the roller and the track with a feeler gauge to ensure even and unbiased wear;
During trial operation, observe the temperature rise of the bearing. After 10-15 minutes of no-load operation, the temperature should be ≤ 40 ℃ and there should be no abnormal heating phenomenon.
2、 Daily maintenance precautions
Lubrication and maintenance
Lubrication cycle: determined according to the working conditions. Generally, lubrication should be carried out every 3-6 months for low dust and low-speed working conditions; Lubrication should be done every 1-2 months under conditions of high dust and heavy load; High temperature conditions (>80 ℃) need to be shortened to once every half month.
Lubricant selection: Lithium based grease and polyurea grease are preferred, high-temperature fluorine grease is selected for high temperature working conditions, and rust proof grease is selected for humid/corrosive working conditions; It is strictly prohibited to mix different types of lubricating grease.
Lubrication method: Add lubricating grease through the bearing lubrication hole until the old grease is completely discharged (the new grease overflows in a uniform state), and then rotate the roller to evenly distribute the lubricating grease on the surface of the raceway; Excess lubricating grease needs to be wiped clean to avoid adsorbing dust.
Cleaning and Protection
Regularly remove dust and debris from the surface and surroundings of the roller to prevent particles from entering the bearing and causing wear on the raceway;
Outdoor or dusty working conditions require the installation of dust covers and sealing rings for roller bearings, or the use of fully sealed roller bearings;
In humid and acidic environments, it is necessary to regularly inspect the anti rust layer of the bearing. If rust spots appear, they should be cleaned and reapplied with anti rust grease or replaced with stainless steel roller bearings in a timely manner.
Condition Monitoring
Appearance inspection: Regularly observe the surface of the outer ring of the roller. If there is pitting, cracking, or severe wear (wear amount>0.5mm), the bearing should be replaced immediately to prevent the fault from expanding.
Operation monitoring: During normal operation, the bearing should have no obvious abnormal noise. If there is a "rustling" friction sound or a "clicking" impact sound, it may be due to insufficient lubrication or damaged rolling elements, and the machine should be stopped for inspection.
Temperature rise monitoring: If the bearing temperature rises abnormally during operation (exceeding the ambient temperature by more than 40 ℃), problems such as grease failure, small clearance, and unbalanced load need to be investigated.
Disassembly and replacement
When disassembling, use a specialized puller to pull out the bearing by applying force through the inner ring. It is strictly prohibited to forcefully pry open the outer ring;
When replacing bearings, it is necessary to simultaneously check the wear of the shaft neck and mounting seat hole. If the wear of the shaft neck is greater than 0.1mm, chrome plating repair or replacement of the shaft parts is required;
Scrapped bearings need to be centrally processed and cannot be discarded at will to avoid safety hazards caused by residual rolling elements.
3、 Taboo items
Do not operate bearings without lubrication, as dry friction can cause rapid erosion of the raceway;
Overloading of bearings is prohibited as exceeding the rated load can cause rolling element breakage and outer ring deformation;
Do not rinse bearings directly with water (unless it is waterproof) to avoid water entering the interior and causing grease emulsification and metal parts rusting.
