The maintenance of double row tapered roller bearings requires systematic management from five aspects: installation, lubrication, operation monitoring, environmental control, and regular maintenance. The specific methods are as follows:
1. Installation specifications: Ensure accurate initial state
Environmental control
Installation should be carried out in a dry and clean environment to avoid dust and impurities from entering the interior of the bearing.
Before installation, clean the mating surface of the shaft and housing with gasoline or kerosene, remove burrs, molding sand and other residues, ensure that the surface roughness Ra is ≤ 0.8 μ m, and the cylindricity error is ≤ 0.005mm.
Heating installation
When the interference fit is large, use oil bath heating (80-100 ℃, not exceeding 120 ℃) or sensor heating, and the heating time is calculated based on the bearing mass of 1.5 minutes/kg.
.Install quickly after heating to avoid cooling causing clearance, and tighten with nuts or stop washers to prevent axial movement.
.Clearance Adjustment
Double row tapered roller bearings have already been adjusted for clearance when they leave the factory. No additional adjustment is required during installation, but the axial play (which should be 2-3 times the clearance value) needs to be measured or verified using an ultrasonic feeler gauge.
. If adjustment is required, the clearance value can be determined by the torque method (suitable pre tightening when the rotational torque suddenly increases by 20%) or by measuring the fit interference between the bearing inner ring and the shaft.2. Lubrication Management: Scientific Selection and Dynamic Maintenance
Lubricant Selection
Lipid Lubrication: Suitable for working conditions with low speeds (dn value<300000, d is the inner diameter of the bearing mm, n is the speed r/min), use lubricating grease containing MoS ₂ or extreme pressure additives (EP) (such as ISO L-XBCHB2 grade), and the viscosity of the base oil should not be less than 100mm ²/s at 40 ℃.
.Oil lubrication: Suitable for high-speed working conditions (dn value>300000), it is necessary to use circulating oil lubrication, oil mist lubrication, or oil spray lubrication to ensure that the viscosity change of the oil does not exceed ± 15% of the initial value, the moisture content is<0.1%, and the particle contamination level meets ISO 4406 standard 18/16/13 or below.
. Lubrication cycle and quantityLubricating grease: Supplement cycle according to formula
T=
60n
d
10
6
estimate (T is the hour, n is the speed, d is the bearing inner diameter), and shorten by 30% -50% in high temperature environment%. The grease injection amount is controlled within 1/3-1/2 of the internal space of the bearing, and the automatic lubrication system injects 0.5-2cm ³ of grease each time, with an interval of 4-8 hours.
Oil lubrication: Regularly take samples to check the condition of the oil, replace immediately if any abnormalities are found, and inspect the sealing system.
.III. Operation Monitoring: Real time Warning and Fault Diagnosis
Vibration Analysis
Install vibration sensors in the vertical, horizontal, and axial directions of the bearing seat, with a sampling frequency of at least 10 times the characteristic frequency of the bearing fault.
. Pay close attention to the acceleration envelope value in the high frequency range (5-10kHz). If there are bearing fault characteristic frequencies (such as BPFO, BPFI, etc.) and their harmonics, it indicates early damage has occurred.Temperature Monitoring
The normal operating temperature should be below 90 ℃, and the temperature rise should not exceed the ambient temperature+40 ℃.
. Using an infrared thermal imager to detect abnormal hotspots, a temperature gradient greater than or equal to 15 ℃ may indicate poor lubrication or alignment issues.Oil abrasive particle analysis
Regularly take samples for ferrography analysis. During normal operation, the abrasive particles should be<50 μ m and have a regular shape.
. If there are flake like abrasive particles or a large amount of oxides larger than 100 μ m, it indicates that the bearing has entered an abnormal wear stage.Fourth, Environmental Control: Protection against Special Working Conditions
Pollution Environmental Protection
In dusty environments such as cement and mining, bearing units with triple lip seals (such as SKF's VA405 design) are selected, and the sealing material is selected according to the medium: NBR rubber is used for general dust, and FKM fluororubber is used for chemical corrosion environments.
.Intermittent operation equipment maintenance
Equipment that has been out of service for a long time should be manually turned 2-3 times a month to prevent static corrosion of the raceway.
. Replace the lubricating grease before reactivation and run in at low speed for 30 minutes for the first time.Fifth, Regular Maintenance: Preventive Maintenance
Appearance Inspection
Regularly inspect the appearance of bearings to confirm that there are no defects such as cracks, fractures, jamming, rust, etc. If there is significant wear or looseness on the inner ring, outer ring, rolling element or cage, it needs to be replaced immediately.
Cleaning and replacement
After disassembling the bearing, record the appearance and confirm the residual amount of lubricant, and take a sample to check the lubricant.
. During cleaning, coarse cleaning (using a brush to remove adhesive) and fine cleaning (rotating in oil for cleaning) are necessary. The cleaning oil should be filtered regularly to maintain cleanliness.Rust prevention treatment
Immediately apply rust proof oil or grease after cleaning to prevent the metal surface from rusting.
. For bearings with sealed structures, the interior should not be cleaned, only the external surface should be wiped.