When the bearing rotates under load, because the raceway surface of the ring and the rolling surface of the rolling elements are constantly subjected to alternating loads, even if the use conditions are normal, fish-like damage (called fish scale damage) will occur on the raceway surface and rolling surface due to material fatigue. do peeling or peeling). The total number of revolutions before such rolling fatigue damage occurs is called the “(fatigue)” life of the bearing. Even if the bearings are identical in structure, size, material, processing method, etc., there will still be large differences in the (fatigue) life of the bearing models when rotating under the same conditions. This is because material fatigue itself is discrete and should be considered from a statistical perspective. Therefore, when a batch of identical bearings are rotated separately under the same conditions, the total number of rotations at which 90% of the bearings do not suffer from rolling fatigue damage is called the “basic rated life of the bearing” (that is, the life at which reliability is 90% ). When rotating at a fixed speed, the total rotation time can also be expressed. However, in actual work, damage phenomena other than rolling fatigue damage may occur. These damages can be avoided by proper bearing selection, installation and lubrication. Basic dynamic load rating Basic dynamic load rating indicates the bearing’s ability to withstand rolling fatigue (i.e. load capacity). It refers to a pure radial load of a certain magnitude and direction (for radial bearings). The inner ring rotates and the outer ring is fixed (or the inner ring Under the condition of fixed outer ring rotation), the basic rated life under this load can reach 1 million revolutions. The basic dynamic load rating of the radial bearing is called the radial basic dynamic load rating, expressed by Cr, and its value is entered in the bearing size table (expressed by C in the following formula).

The basic rating life formula (2) represents the basic rating life calculation formula of the bearing; the formula (3) represents the life formula expressed in time when the bearing speed is fixed. (Total number of revolutions) L10 = ( C )PP …………… (2) (time) L10k = …………… (3) 10660n ( ) CPP: basic rated life, 106 revolutions: basic rated life, h: Equivalent dynamic load, N{kgf}: Basic dynamic load rating, N{kgf}: Rotation speed, rpm: Life index L10pnCPL10k ball bearing…………P=3 roller bearing…………P=310 therefore , as the usage conditions of the bearing, assuming the equivalent dynamic load is P and the rotation speed is n, then the basic rated dynamic load C of the bearing required to meet the design life can be calculated by Equation (4). Select the bearing that meets the C value from the bearing size table to determine the bearing size C=P(L10k The calculation formula is as follows: L10k=500fhf………………(5) Life coefficient: fh=fn…………(6C P Speed coefficient: = (0.03n) p……………… (7)-1fn=( )500x60n106Using the calculation chart [reference picture], fh, fn and L10h can be easily obtained. When selecting bearings, the fatigue life is intentionally improved. It is uneconomical to choose large bearings and the strength of the shaft, Stiffness, installation dimensions, etc. are not necessarily based on fatigue life alone. Bearings used in various machinery have a benchmark design life, that is, the empirical fatigue life coefficient, based on the conditions of use. Please refer to the table below.

n 1.5 10 0.9 0.8 0.7 0.6 0.5 0.4 0.35 0.3 0.25 02019018017 016 015

n 10 20 30 40 50 70 100 200 300 500 1000 2000 3000 5000 10000

0.6 0.7 0.8 0.9 10 1.5 2.0 2.5 3.0 3.5 4.0 5.0 6.0

100 200 300 400 500 700 1000 2000 3000 5000 10000 20000 30000 50000 100000h10h1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.55 0. 5 0.45 0.4 0.35 0.3 0.25 0.20.190.1810 20 40 50 70 100 200 300 500 1000 2000 3000 5000 10000nn0.62 0.7 0.6 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.71.81.92.0 2.5 3.0 3.5 4.0 4.5 4.9100 200 300 400 500 700 1000 2000 3000 5000 1 0000 20000 30000 50000 100000h 10h

[Ball Bearing] Speed Life Speed Life [Roller Bearing] Correspondence Table of Experienced Fatigue Life Coefficient fh and Used Machinery Table 3 Conditions fh Value and Used Machinery ~ 3 2 ~ 4 3 ~ 5 4 ~ 7 6 ~ Do not use frequently or for a short time Frequent use, but it is required to ensure that the operation is not continuous, but the operation time is longer than 8 hours a day, or continuous operation for 24 hours for a long time, and it is not allowed to stop operation due to accidents. Small appliances such as household vacuum cleaners and washing machines are not allowed to be stopped; electrician tools are rolled Roller diameter motors for agricultural machinery and household air conditioners; small motors for construction machinery; deck cranes; general cargo starters; gear bases; automobiles; escalator conveyor belts; elevator factory motors; lathes; general gear devices; vibrating screens; crushers; grinding wheels ; Centrifugal separator; air-conditioning equipment; fan bearings; woodworking machinery; large motors; passenger car axle crane ship; compressor; important gear device mining crane; punch inertia wheel (flywheel); main motor for vehicles: locomotive axle, papermaking machinery tap water equipment ; Power plant equipment; Mine drainage equipment.