Thrust bearing. Angular contact bearings. Ball thrust bearing

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Bearings are technical devices that support rotating axles and shafts. They are able to receive radial and axial loads directly acting on the axle or shaft, and then transfer them to the frame, body or other parts of the structure. The task of the bearing at the same time is to hold the shaft in space, allowing it to freely swing, rotate or move linearly with minimal energy loss. The performance, efficiency and, of course, the durability of the machine depend on the quality of this device.

Types of bearings

Based on the principle of operation, all devices are divided into gas-dynamic, hydrostatic, gas-static, hydrodynamic, magnetic, sliding and rolling. The last two types are usually used in mechanical engineering. The rolling bearing consists of a cage and two rings that separate them. A groove runs along the outer part of the inner ring and the inner part of the outer ring - this is the path along which the rolling elements (rollers or balls) roll whendevice is in use.

According to the perception of the load, radial (for radial and small axial load), thrust (for axial load), thrust-radial (for axial and small radial load) and angular contact bearings (for combining axial and radial load) are divided.

Single-row, double-row and multi-row devices are distinguished by the number of rows for balls or rollers. Depending on the ability to compensate for the existing misalignments of the shafts, they are divided into non-self-aligning bearings, which allow mutual misalignment of the rings up to eight degrees, and self-aligning (misalignment up to four degrees).

Symbol

Russian marking of such devices consists of a symbol standardized in accordance with GOST 3189-89, as well as a manufacturer's code. Thus, the marking includes seven digits of the main designation (if the values of the signs are zero, it can be reduced to two characters) and an additional one located to the right / left of the main one. If it is on the left, it is always separated by a "-" (dash), and if it is on the right, it starts with a letter. Reading is always done from right to left, whether for radial or thrust bearings.

GOST prescribes to arrange the marking elements in a certain sequence. So, first a series of widths (one digit) is indicated, then a design variety (two digits), then a bearing type (one digit), a series of diameters (one digit) and a symbolinner diameter (two digits).

Where is a thrust bearing used?

There are very few machines in which there are no rotating parts. Parts such as drums, levers, wheels, axles, shafts, etc. are usually required - everyone who deals with cars knows this. So, without bearings here it can not do. Any vehicle needs good care and periodic repairs, so these devices have to be changed from time to time. But the thrust bearing is not only an indispensable attribute of a car, it is used in metallurgical, power equipment, mining machines. Such designs allow to enhance the speed qualities of a particular part, so they are often used in centrifuges, car wheels, worm gears, spindles and more.

Ball and roller thrust devices

The ball thrust bearing is designed to take axial loads and is non-self-aligning. They produce single-row devices that perceive an axial one-sided load, and double-row devices perceive a two-sided one. Such structural units are used in vertical shafts, jacks, rotating centers of machine tools that cut metal.

Thrust roller bearing is used when there is a very large axial load. These devices can be of three types:

• with tapered rollers - designed to work under extremely high loads, high rotational speeds, shocks;
• scylindrical rollers - used to work at low speeds, but with significant loads;
• with spherical rollers - have self-aligning properties, can carry significant axial and radial loads.

Roller thrust bearing is used in thrust blocks of piercing mills, extruders, heavily loaded vertical shafts, alternators. In addition, it is part of the swivel units of metallurgical equipment.

Angular contact bearings

These devices are also used in various industries: machine and tank building, chemical industry and others. These structural units are able to perceive both types of load at once: both axial and radial. Its maximum value directly depends on the angle at which the rolling elements come into contact with the raceways. It is possible to use an angular contact bearing having a four-point contact. However, it should be noted that in general technical industries, single-row and double-row devices are most widely used.

Varieties of angular contact bearings

Constructive nodes can be made in different versions. The angular contact ball bearing can be open or have a protective metal washer or contact seal. Four-point contact devices have split outer or inner rings and are more suitable for axial loads. Angular contact ball bearings are often equipped with a cage made ofglass-filled polyamide. But there are also structural units with a brass dotted or stamped steel cage. Such bearings perceive radial and axial unilateral load. On the inner or outer ring there is a bevel on the side of the rolling elements, so often the number of rollers in this version of the device exceeds the number of balls in the corresponding angular contact structural unit. This bearing is able to carry more load than a radial bearing of the same size.

Angular contact roller bearing generally has a rolling element of a conical type. Due to the location of the rollers to the axis of rotation at a certain angle, this type of device is able to perceive combined loads. At the same time, an angular contact tapered bearing has a much lower allowable speed than a cylindrical roller assembly. The level of acceptance of axial loads is determined by the taper angle: with its increase, the radial load decreases, and as a result, the effective axial load increases. If you want to use such bearings, you need to make sure that there is no misalignment of the bearing seats and the shaft axis in which they are installed.

Roller Angular Contact Taper Options:

• 7000 - main;
• 27000 - high taper angle;
• 97000 - double row;
• 77000 - four-row.

Types 27000 and 7000

Designed for the perception of radial and axial unilateral loads. Such structural units require adjustment of axial clearances and installation of outer rings - both during installation and during operation.

Type 97000

These devices are able to take one-sided and two-sided radial and axial loads simultaneously. If it is required to change the radial or axial clearance, the distance ring installed in the middle of the inner rings is ground in the bearing. The maximum load in structural units of this type is 1.7 times higher than that allowed for single row bearings.

Type 77000

Devices of this type are designed to absorb significant radial and minor bilateral axial loads. Such a structural assembly can withstand much greater radial forces than the corresponding single row.

Bearing selection

When choosing the type and size of the device, consider the following factors:

• character of the load (variable, shock, vibration, constant);
• required resource (in million revolutions or hours);
• load direction and value (axial, radial, combined);
• environmental condition (dust content, temperature, acidity, humidity);
• frequency of rotation of the assembly ring;
• special requirements that depend on the design of the bearing (required dimensions, self-aligning properties, noise reduction, etc.).

Dimensions and accuracy classes

Such devices havesize series. By overall dimensions, they are divided into heavy / medium / light / extra light / extra light, and by width - into extra wide / wide / normal / narrow. The most common are medium, light and extra light varieties.

They allocate accuracy classes of structural units: super-precision / precision / high / increased / normal. They also produce bearings with an accuracy class below normal (the most inaccurate) or above super-precision (the most accurate). Depending on this parameter and other additional requirements, such as the level of vibration, etc., all devices are divided into categories: classes A, B, C.

In conclusion, we will give a decoding of the symbols for bearing types:

• 0 - radial/ball;
• 1 - radial/ball spherical;
• 2 - radial/roller with short cylindrical rollers;
• 3 - radial/roller with spherical rollers (barrel shape);
• 4 - radial/roller with needle or cylindrical long rollers;
• 5 - radial/roller with twisted rollers;
• 6 - angular contact/ball;
• 7 - conical/roller;
• 8 - thrust-radial / ball, thrust / ball;
• 9 - Thrust Radial/Roller, Thrust/Roller.