Section 1 Basic structure of rolling bearings
Rolling bearings developed on the basis of sliding bearings, whose working principle is to replace sliding friction with rolling friction, are generally composed of two rings, a set of rolling elements and a cage, which are highly versatile, standardized and serialized. High mechanical base pieces. Due to the different working conditions of various machines, various requirements are put forward for rolling bearings in terms of load capacity, structure and performance. For this reason, rolling bearings require various structures. However, the most basic structure is composed of inner ring, outer ring, rolling elements and cage.
The functions of various parts in the bearing are:
For radial bearings, the inner ring usually has a tight fit with the shaft and runs together with the shaft, and the outer ring usually forms a transition fit with the bearing seat or the mechanical housing hole to play a supporting role. However, in some occasions, the outer ring is also running, and the inner ring is fixed to act as a support, or both the inner ring and the outer ring are running at the same time. For thrust bearings, it is called the shaft ring that fits tightly with the shaft and moves together, and it is called the seat ring that is in transition fit with the bearing seat or the hole of the mechanical housing and plays a supporting role. Rolling elements (steel balls, rollers or needle rollers) are usually evenly arranged between two rings for rolling motion with the help of cages in the bearing. Its shape, size and quantity directly affect the load capacity and performance of the bearing. In addition to separating the rolling elements evenly, the cage can also play a role in guiding the rotation of the rolling elements and improving the internal lubrication performance of the bearing.
Section 2 Classification of Rolling Bearings
1. Classification by rolling bearing structure type
(1) Bearings are divided into:
1) Radial bearings - mainly used for rolling bearings that bear radial loads, and their nominal contact angles range from 0 to 45. According to the different nominal contact angles, it is further divided into: radial contact bearings - radial bearings with a nominal contact angle of 0; radial angular contact bearings - radial bearings with a nominal contact angle greater than 0 to 45.
2) Thrust bearings - mainly used for rolling bearings bearing axial loads, and their nominal contact angles are greater than 45 to 90. According to the nominal contact angle, it is divided into: Axial contact bearings - thrust bearings with a nominal contact angle of 90°; thrust angular contact bearings - thrust bearings with a nominal contact angle greater than 45° but less than 90°.
(2) Bearings are classified according to the type of rolling elements:
1) Ball bearings - the rolling elements are balls:
2) Roller bearings - the rolling elements are rollers. According to the types of rollers, roller bearings are divided into: Cylindrical roller bearings ---- bearings whose rolling elements are cylindrical rollers, the ratio of the length to diameter of cylindrical rollers is less than or equal to 3; needle roller bearings ---- The rolling element is a needle roller bearing, the ratio of the length to the diameter of the needle roller is greater than 3, but the diameter is less than or equal to 5mm; tapered roller bearing ---- the rolling element is a tapered roller bearing; spherical roller bearing one by one The rolling elements are spherical roller bearings.
(3) Bearings can be divided into:
1) Self-aligning bearing--the raceway is spherical, which can adapt to the angular deviation and angular motion between the axis lines of the two raceways;
2) Non-aligning bearings (rigid bearings) ---- bearings that can resist the angular deviation of the axis line between the raceways.
(4) According to the number of rows of rolling elements, bearings are divided into:
1) Single row bearings - bearings with one row of rolling elements;
2) Double row bearings - bearings with two rows of rolling elements;
3) Multi-row bearings - bearings with more than two rows of rolling elements, such as three-row and four-row bearings.
(5) According to whether the parts can be separated, the bearings are divided into:
1) Separable bearings - bearings with separable parts;
2) Non-separable bearings ---- after the final assembly of the bearings, the rings cannot be separated freely at will.
(6) The bearing can be divided into various structural types according to its structural shape (such as whether there is a filling groove, whether there is an inner and outer ring and the shape of the ferrule, the structure of the rib, and even whether there is a cage, etc.).
2. Classification according to the size of rolling bearings Bearings are divided into:
(1) Miniature bearings - bearings with a nominal outer diameter of 26mm or less;
(2) Small bearings - bearings with a nominal outer diameter ranging from 28 to 55mm;
(3) Small and medium-sized bearings - bearings with a nominal outer diameter ranging from 60-115mm;
(4) Medium and large bearings - bearings with a nominal outer diameter ranging from 120-190mm
(5) Large bearings - bearings with a nominal outer diameter ranging from 200-430mm;
(6) Extra-large bearings - bearings with a nominal outer diameter of 440mm or more.
