First, the rolling bearing life calculation criteria
1, for the general working conditions of the rotary rolling bearing, pitting occurs frequently, mainly for life calculation, static strength check if necessary;
2. For bearings with no rotation, swing or low rotation speed (N ≤10 r/min), plastic deformation is required to be controlled, and static strength calculation is only needed;
3, for high-speed bearing due to heat caused by the adhesive wear, burns are often outstanding contradictions, in addition to the calculation of life, also need to check the limit speed.
Calculation of rated life of rolling bearing
1. Fatigue pitting
The rolling body and the inner ring (or outer ring) rotate continuously. The rolling body and the contact surface of the raceway are subjected to variable stress.When the number of stress cycles reaches a certain value, pitting points and pits occur on the working surface of the rolling body or raceway.As shown in the figure.
2. Rated life
A group of bearings of the same type operating under the same conditions, 90% of the bearings do not appear fatigue pitting rotation of the total number of revolutions, or the time experienced at a certain speed.
3. Rated dynamic load Cr
The rated life of the same batch of bearings is one million revolutions per load.
4. Equivalent dynamic load P
The rated dynamic load of the rolling bearing is determined according to the experiment under the condition that the axial bearing only bears radial load and the thrust bearing only bears axial load. If the actual load on the bearing is different from the above conditions, the actual load must be converted into equivalent dynamic load.
5. Calculation formula of rated life
1) Calculation of equivalent dynamic load P of rolling bearing
2) Calculation of axial load of rolling bearing
Note:
A. Judge the movement trend of the shaft according to the external axial force on the shaft and the additional axial force on the two bearings, and then analyze which end of the bearing is compressed and which end of the bearing is relaxed in combination with the mounting mode of the bearing;
B. Total axial force at the release end = additional axial force;
Total axial force on the compression end = additional axial force on the release end + additional axial force on the release end.
3) Select bearings according to rated static load
