Bearings - a technical device which support for rotating axles and shafts.They are capable of taking radial and axial loads, direct impact on the axle or shaft, and then transfer them to the frame, chassis or other parts of the structure.Target bearing at the same time - to hold the shaft in the space, allowing it to freely swing, rotate or move linearly with minimal loss of energy.The quality of this device depends on performance, efficiency and, of course, the durability of the machine.
kinds of bearings
Based on the principle of work, all devices are divided into the gas-dynamic, hydrostatic, gas-static, hydrodynamic, magnetic, sliding and rolling.The latter two are usually used in mechanical engineering.Bearing separator consists of two rings which separates them.On the outer part of the inner ring and the inner part of the outer groove passes - a track along which the rolling elements ride (rollers or balls) when the device involved in operation.
on the perception of the load is shared radial (for radial and small axial load), persistent (for axial loads), thrust bearings (for axial and low radial load) and angular contact bearings (for the combination of axial and radial load).
According to the number of rows for the balls or rollers isolated single row, double row and multi-device.Depending on the ability to compensate for misalignment of shafts available, shared nesamoustanavlivayuschiesya bearings, which allow mutual misalignment of up to eight degrees, and self-aligning (skewed to four degrees).
Symbol
Russian labeling of such devices consists of a symbol, standardized in accordance with GOST 3189-89, as well as the code of the manufacturer.Thus, the labeling includes seven main numbers notation (if characteristic values are zero, can be reduced to two characters) and further to the right / left of the main.In case it is always placed on the left separated by "-" (dash), and if right, it begins with any letter.Reading is always carried out from right to left, whether radial or thrust bearings.
Standard prescribes have labeling elements in sequence.So, first specify a series of widths (one digit), followed by a variety of structural (two digits), followed by the type of bearing (one digit), a series of diameters (one digit), and the symbol of the inner diameter (two digits).
Where to use ball bearings?
machine in which there are no rotating parts, is very small.Such parts as drums, levers, wheels, axles, shafts and so on. E., As a rule, always there - everyone knows who is dealing with cars.So, without bearings are not complete.Any vehicle in need of good care and periodic repairs, and that the devices have to be changed from time to time.But the thrust bearing - is not only an indispensable attribute of the car, it is used in the steel, energy, machinery, mining industry.This type of design allows for enhanced speed qualities of this or that detail, so they are often used in centrifuges, car wheels, worm gears, spindles, and so on.
Ball and roller bearings device
Ball thrust bearing designed for axial loads, it is nesamoustanavlivayuschimsya.Producing single-row devices that accept a one-way axial load, and double row - two-way perceive.Such structural components are used in vertical shafts, jack, rotating centers, machine tools, metal cutting.
roller thrust bearings used when operating a very large axial load.These devices can be of three types:
- tapered roller - designed to operate at extremely high loads, high speeds, bumps;
- cylindrical roller - used to work at low speeds, but at high loads;
- with spheroconical rollers - have properties samoustanavlivaemosti may incur substantial axial and radial loads.
roller thrust bearings used in the refractory blocks piercing mills, extruders, heavy-duty vertical shafts, alternators.Furthermore, it is part of the swing metallurgical equipment.
Angular contact bearings
These devices are also used in different fields of industry: mechanical engineering and tank building, chemical industry and others.These structural components are able to perceive at once both types of load: both axial and radial.Its maximum value depends on the angle at which the rolling bodies in contact with the raceways.Possible to use angular contact ball bearing having a four-point contact.However, it should be noted that in general engineering industries most widely used single and double row unit.
Varieties of angular contact bearings
Structural components can be performed in different ways.Bearings Angular Ball can be open or have a protective metal washer or lip seal.The devices have a four-point contact detachable external or internal rings and more suitable for axial loads.Bearing angular contact ball often equipped with a cage of glass fiber reinforced polyamide.But there are also structural assemblies with brass or steel point pressed separator.These bearings accept radial and axial load of one-sided.On the inner or outer ring has a bevel on the part of the rolling elements, so often the number of rollers in this embodiment, the device exceeds the number of balls in the corresponding angular contact constructive node.This bearing is able to perceive a greater load than the radial of similar size.
roller angular contact ball bearing, as a rule, has a body rolling cone type.By arranging the rollers to the axis of rotation at a certain angle, this type of device is able to perceive the combined load.At the same time, the angular contact ball bearing cone has a much lower permissible speed than the structural unit with cylindrical rollers.The level of acceptance of the axle loads is determined by the cone angle: when increasing the radial load decreases, and thus increases the thrust.If you wish to use these bearings need to make sure that there is no distortion of nests bearings and shaft axis, in which they are installed.
Options roller angular contact tapered devices:
- 7000 - basic;
- 27000 - high cone angle;
- 97000 - two-row;
- 77000 - four row.
types 27000 and 7000
Designed for radial and axial loads unilateral.Such structural components need to adjust the axial clearance and mounting the outer rings - both during installation and during operation.
Type 97000
These devices are able to take unilateral and bilateral radial and axial loads simultaneously.If you want to change the radial or axial clearance in the bearing podshlifovyvaetsya remote ring mounted in the middle of the inner rings.Maximum load in the structural units of this type is 1.7 times greater than that which is acceptable for single-row bearings.
Type 77000
Devices of this type are made to receive significant bilateral radial and axial loads minor.Such a structural unit can withstand a much greater effect radial forces than the corresponding single-row.
Selecting bearing
When choosing the type and size of the device should take into account the following factors:
- load conditions (variable, shock, vibration, constant);
- necessary resource (in millions of revolutions or hours);
- direction and value of the load (axial, radial, combined);
- environmental conditions (dust, temperature, acidity, humidity);
- speed ring structural assembly;
- special requirements, which depend on the design of the bearing (required dimensions, properties samoustanavlivaemosti, noise reduction and so on. N.).
dimensions and accuracy classes
Such devices have three-dimensional series.In overall dimensions, they are divided into heavy / medium / light / very light / ultra-light, and the width of the - on the most wide / wide / normal / narrow.The most common are medium, light and extra light varieties.
There are classes of accuracy of structural components: сверхпрецизионный/прецизионный/высокий/повышенный/нормальный.Also produces bearings, whose accuracy class is below normal (very inaccurate) super-precision or higher (the most accurate).Depending on this setting and other additional requirements, such as vibration and so on, all the devices are divided into three categories: Class A, B, and C. In conclusion
give interpretation of symbols bearing types:
- 0 - radial / ball;
- 1 - radial / spherical ball;
- 2 - radial / cylindrical roller with a short video;
- 3 - groove / roller of a spherical roller (barrel-shaped);
- 4 - radial / needle roller or cylindrical roller long;
- 5 - radial / bearings with spiral rollers;
- 6 - angular contact ball / ball;
- 7 - conical / roll;
- 8 - Axial / ball, hard / ball;
- 9 - Axial / roller, thrust / roller.
