First, the main function of the rolling bearing:
To ensure that the bearing has a sufficient life, it is used to support rotating (or oscillating) parts, transfer load, reduce the friction between the pairs of motion, make it flexible (or swing).
Second, the basic requirements of the bearing:
Can meet the working conditions required by the load, speed, accuracy, dynamic performance (noise, vibration), ambient temperature and life.
Third, the basic structure of the rolling bearing:
It consists of an inner ring, an outer ring, rolling elements and a cage (commonly known as the four major pieces).
The inner ring is assembled with the shaft, outer ring and housing bore. When the inner ring or the outer ring is a rotating ferrule, a tight fit is used, and when it is not a rotating ferrule, a transition fit is used.
Rolling elements (balls,
Rollers or needles) are the core parts of rolling bearings. When the inner and outer rings rotate relative to each other, the rolling elements roll between the raceways of the inner and outer rings. The shape, size, and number of rolling elements directly affect the bearing load capacity and performance.
The cage can distribute the rolling elements evenly, guide the rotation of the rolling elements and improve the internal lubrication performance of the bearing.
Fourth, the material of the rolling bearing material rings and rolling elements must have the characteristics: high contact fatigue strength; high hardness; high purity; good wear resistance; good tissue stability; good machining performance.
Commonly used bearing materials (ferrules and rolling elements):
High carbon Bearing steel: GCr15, GCr15SiMn and other alloy steel, heat treatment hardness is generally 60 ~ 65HRC. It is currently the most widely used bearing material.
Carburized bearing steels: 20CrMo, 20CrNiMo, etc. The surface hardness after carburizing heat treatment is generally 59 to 64HRC, and the hardness of the core is generally 30 to 45HRC. Good toughness, able to withstand high impact loads.
The cage can be stamped with 08# or 10# steel cages, HPb59-1 solid brass cages, GRPA66 engineering plastic cages, etc. as required.
V. Bearing Clearance Radial play of a rolling bearing refers to the amount of movement of one ferrule fixed and the other ferrule moving from one extreme position to the other extreme position perpendicular to the axis of the bearing. The correct choice of bearing clearance has a great influence on the mechanical running accuracy, bearing life, frictional resistance, temperature rise, vibration and noise. If the selection of the radial bearing clearance is too small, the number of rolling elements bearing the load will increase, the contact stress will decrease, and the operation will be more stable. However, the frictional resistance will increase, and the temperature rise will also increase. On the contrary, the contact stress increases, the vibration is large, the frictional resistance decreases, and the temperature rise is low. Therefore, according to the conditions of use of the bearing, it is of great significance to select the most appropriate clearance value.
VI. Tolerance grades and matching features of rolling bearings The tolerances of rolling bearings are divided into 0 (normal), 6x, 6, 5, 4, and 2 precision grades. Levels are increased from 0 (normal) level to 2 level. The 6x class is for tolerance grades between 0 (normal) grade and 6 grades for
Tapered Roller Bearings. The bearings in general use a 0 (normal) grade tolerance class. Tolerance grades are indicated in the bearing designations in the form of P6, P5, etc. 0 (normal) grades are not represented in the designators.
May 06, 2024
