There are raceways on the inner and outer rings of angular contact ball bearings, and the inner and outer rings can make relative displacement along the bearing axis. This kind of bearing is especially suitable for bearing compound load, that is, radial and axial load acting at the same time. The axial load bearing capacity of angular contact ball bearing increases with the increase of contact angle α. The contact angle is the angle between the line of contact point between ball and raceway in radial plane and the vertical line of bearing axis.
The types of angular contact ball bearings are divided into: α = 15 ° angular contact ball bearings (70000C type); α = 25 ° angular contact ball bearings (70000ac type); α = 40 ° angular contact ball bearings (70000b type); back-to-back double angular contact ball bearings [70000C (AC, b) / DB type]; face-to-face double angular contact ball bearings [70000C (AC, b) / DF type]; series double angular contact ball bearings [70000C (AC, b) / dt type]; Double row angular contact ball bearing with ball notch (type 00000); double row angular contact ball bearing without ball notch (type 00000a); double row angular contact ball bearing without ball notch with dust cover on one side (type 00000a-z); double row angular contact ball bearing without ball notch with dust cover on both sides (type 00000a-2z); double row angular contact ball bearing without ball notch with seal ring on one side (type 00000ars); double row angular contact ball bearing with dust cover on both sides (type 00000a-2z); There are 13 kinds of double row angular contact ball bearings (00000a-2rs type) and four point angular contact ball bearings (qj0000 type).
Single row angular contact ball bearings can only bear axial load in one direction, which will cause additional axial force when bearing radial load. And it can only limit the axial displacement of shaft or shell in one direction. The contact angle of angular contact ball bearing is 40 degrees, so it can bear large axial load. The angular contact ball bearing is a non separating design. The shoulders on both sides of the inner and outer rings are different. In order to improve the load capacity of the bearing, the shoulder of one side will be machined lower, so that more steel balls can be loaded into the bearing.
The double row angular contact ball bearing can bear larger radial load, mainly radial and axial combined load and torque load, and limit the axial displacement of the shaft. Among the components mainly used to limit the bidirectional axial displacement of shaft and shell, the tilting ability between the inner ring and outer ring of double row angular contact ball bearing is limited. The allowable tilting angle depends on the internal clearance, bearing size, internal design and the force and torque acting on the bearing, and the maximum allowable tilting angle should ensure that there is no excessive additional stress in the bearing. If there is an inclination angle between the inner and outer rings of the bearing, the service life of the bearing will be affected, and the running accuracy of the bearing will be reduced, and the running noise will be increased. Nylon cage or brass solid cage is generally used for double row angular contact ball bearings. When installing double row angular contact ball bearing, it should be noted that although the bearing can bear two-way axial load, if there is a ball loading gap on one side, the main axial load should not pass through the groove side with the gap. When the bearing is used, attention should be paid to make the raceway on the side without ball loading gap bear the main load.
Paired double ball bearing
If it is installed in pairs, make the outer rings of a pair of bearings opposite, that is, the wide end face to the wide end face, and the narrow end face to the narrow end face. In this way, the additional axial force can be avoided, and the shaft or shell can be limited in the range of axial clearance in two directions.
Because the raceway of its inner and outer rings can have relative displacement on the horizontal axis, it can bear both radial load and axial load - combined load (single row angular contact ball bearings can only bear single direction axial load, so they are usually installed in pairs).
Cage materials are brass, synthetic resin, etc., according to the bearing form, use conditions and distinction.
Most of the angular contact ball bearings are manufactured by foreign bearing manufacturers, and most of them are used in imported equipment in China, such as angular contact ball bearings 3204rs, etc,
The narrow side is outside, the wide side is inside, the other wide side is inside, and the narrow side is outside, which means back-to-back contact.
characteristic
1. Bearings for general assembly
Universal matched bearings are specially processed. When the bearings are installed close to each other, any combination method can achieve the given internal clearance or preload, as well as the average load distribution, without the use of gaskets or similar devices.
Paired bearings are used when the load bearing capacity of a single bearing is insufficient (using the channeling configuration) or when bearing combined load or axial load acting in two directions (using the back-to-back or face-to-face configuration).
2. Bearings of basic design (cannot be used as general assembly) are used for the configuration of single bearing
The basic design of single row angular contact ball bearings is mainly used in the configuration of only one bearing in each position. Its width and protrusion are common tolerance. Therefore, it is not suitable to install two single row angular contact ball bearings close to each other.
Accuracy class
The accuracy class of angular contact ball bearings includes dimensional tolerance and rotational accuracy. The accuracy from low to high is expressed as P0 (common), P6 (p6x), P5, P4, P2. In addition, P3, P7 and P9 are also used in European and American brands to indicate the accuracy level. P3 is equivalent to P6 of ISO and JIS standards, P7 is equivalent to P4, and P9 is equivalent to P2.
type
Angular contact ball bearings are: 7000c (∝ = 15 °), 7000ac (∝ = 25 °) and 7000b (∝ = 40 °). The lock of this kind of bearing is on the outer ring. Generally, the inner and outer rings can't be separated. It can bear the combined load of radial and axial as well as the axial load in one direction. The ability to bear axial load is determined by the contact angle. The larger the contact angle is, the higher the ability to bear axial load is. The bearing can limit the axial displacement of shaft or shell in one direction.
The ultimate speed of contact ball bearing is high, it can bear both radial load and axial load, and can also bear pure axial load. Its axial load capacity is determined by the contact angle, and increases with the increase of contact angle.
Single row angular contact ball bearing
Single row angular contact ball bearings can only bear axial load in one direction. When bearing radial load, it will cause additional axial force and must apply corresponding reverse load. Therefore, this kind of bearings are generally used in pairs. Double row angular contact ball bearing can bear larger radial and axial combined load and torque load, which are mainly radial load. It can limit the axial displacement of shaft or shell in two directions, and the contact angle is 30 degrees.
Bearing code: 7
Mounting angular contact ball bearings in pairs
The paired angular contact ball bearing can bear the radial and axial combined load mainly with radial load, and can also bear the pure radial load. The series configuration can only bear the axial load in a single direction, while the other two configurations can bear the axial load in any direction. This type of bearing is usually selected and assembled by the manufacturer and submitted to the user in pairs. After installation, there is preloading interference, and the ring and steel ball are in the axial preloading state. Therefore, the stiffness and rotation accuracy of the whole set of bearings as a single support are improved.
With back-to-back configuration, the rear code is dB (such as 70000 / DB), and the load line of back-to-back matched bearings is separated from the bearing shaft. It can bear the axial load in two directions, but the load in each direction can only be borne by one bearing. Back to back bearings provide a relatively rigid bearing configuration and can withstand overturning moments.
In face-to-face configuration, the rear code is DF (such as 70000 / DF), and the load lines of the face-to-face matched bearings converge to the bearing shaft. It can bear the axial load in two directions, but the load in each direction can only be borne by one bearing. This configuration is not as rigid as the back-to-back pair, and it is not suitable for bearing overturning moment. The rigidity and capacity of bearing overturning moment of this configuration are not as good as that of DB configuration, and the bearing can bear bidirectional axial load;
In series configuration, the rear code is DT (such as 70000 / DT). In series configuration, the load lines are parallel, and the radial and axial loads are evenly shared by the bearings. However, the bearing group can only bear the axial load in one direction. If the axial load acts in the opposite direction, or if there is a compound load, a third bearing must be added, which is adjusted relative to the series matched bearing. This configuration can also be in series with three or more bearings at the same support, but can only bear the axial load in one direction. Usually, in order to balance and limit the axial displacement of the shaft, a bearing which can bear the axial load in the other direction should be installed at the other support.
Bearing code: 0
Load capacity (brief)
The following contents are only for the load capacity of paired bearings, and the basic rated load and fatigue limit load given in the product table are only applicable to single bearing.
*Basic dynamic load rating for standard bearings in any configuration and SKF Explorer bearings in back-to-back or face-to-face configuration
C = 1, 62xc single bearing
*Basic dynamic load rating for SKF Explorer bearings in series configuration
C = 2XC single bearing
*Basic static load rating
Co = 2xco single bearing
*Fatigue limit load
Pu = 2xpu single bearing
Types of structural deformation
The characteristic of double row angular contact ball bearing is that it can bear the combined load of radial and axial load at the same time and limit the axial displacement of the shaft. Compared with the two-way thrust ball bearing, this kind of bearing has higher limit speed, 32 degree contact angle, good rigidity, and can withstand large overturning moment. It is widely used in the front wheel hub of cars (some models also use double row tapered roller bearings of the same size).
There are four structural deformations of double row angular contact ball bearings
Type A: Standard Design of bearing with outer diameter less than or equal to 90mm. There is no ball loading gap, so it can bear the same two-way axial load. The cage is made of light glass fiber reinforced nylon 66. The temperature rise of the bearing is very small.
Type A: Standard Design of bearing with outer diameter greater than 90mm. There is a ball loading gap on one side, equipped with Z steel plate stamping cage or brass solid cage.
Type E: it is a reinforced structure with a ball loading gap on one side, which can hold more steel balls, so it has higher bearing capacity.
Double row angular contact ball bearings of type A and type E can be equipped with dust cover (non-contact) or sealing ring (contact) on both sides. Sealed bearings are filled with anti rust lithium grease, the operating temperature is generally between - 30 ℃ and 110 ℃. There is no need to re lubricate during use and no heating before installation.
When installing double row angular contact ball bearing, it should be noted that although the bearing can bear bidirectional axial load, if there is a ball loading gap on one side, the main axial load should not pass through the groove side of the notched side.
Main uses
Single row angular contact ball bearings: machine tool spindle, high frequency motor, gas turbine, centrifugal separator, small car front wheel, differential pinion shaft, booster pump, drilling platform, food machinery, dividing head, repair welding machine, low noise cooling tower, electromechanical equipment, coating equipment, machine bed slot plate, arc welding machine
Double row angular contact ball bearings: oil pump, roots blower, air compressor, various transmissions, fuel injection pump, printing machinery, planetary reducer, extraction equipment, cycloid reducer, food packaging machinery, electric welding machine, electric soldering iron, square box, gravity spray gun, wire stripper, half shaft, inspection and analysis equipment, fine chemical machinery
Installation skills
High speed precision angular contact ball bearing is mainly used in high-speed rotating occasions with light load, which requires high precision, high speed, low vibration at low temperature and certain service life. It is often used as the supporting parts of high-speed motorized spindle. It is the key component of high-speed motorized spindle of internal surface grinder.
Installation form
The automatic selection of angular contact ball bearings is available. The installation forms of angular contact ball bearings are back-to-back, face-to-face and series arrangement. When the bearings are installed back-to-back (the wide end faces of the two bearings are opposite), the contact angle line of the bearings diffuses along the direction of the rotation axis, which can increase the radial and axial support angle rigidity, and has the largest anti deformation ability; when the bearings are installed face-to-face (the narrow end faces of the two bearings are opposite), the contact angle line of the bearings converges towards the direction of the rotation axis, and the support angle rigidity is small. Because the inner ring of the bearing extends out of the outer ring, when the outer rings of the two bearings are pressed together, the original clearance of the outer ring is eliminated, which can increase the preload of the bearing; when the bearing is installed in series (the wide end faces of the two bearings are in one direction), the contact angle lines of the bearings are in the same direction and parallel, which can make the two bearings share the working load in the same direction. However, in order to ensure the axial stability of the installation, two pairs of bearings arranged in series must be installed opposite at both ends of the shaft.
Main technical specifications:
1. Bearing accuracy index: exceeding GB / 307.1-94 grade P4 accuracy
2. High speed performance index: DMN value 1.3 ~ 1.8x106/min
3. Service life (average): > 1500 H
The service life of high-speed precision angular contact ball bearing is closely related to the installation. The following matters should be paid attention to
1. The bearing should be installed in a clean and dust-free room. The bearing should be carefully selected and matched. The bearing spacer should be ground. The parallelism of the spacer should be controlled below 1 um on the premise of maintaining the same height of the inner and outer rings;
2. The bearing should be cleaned before installation. When cleaning, the inner ring slope should be upward, and the hand sensing should be flexible without stagnation. After drying, the specified amount of grease should be put in. In case of oil mist lubrication, a small amount of oil mist should be put in;
3. Special tools shall be used for bearing installation, with uniform force and no knocking;
4. The bearing shall be kept clean and ventilated, free of corrosive gas, and the relative humidity shall not exceed 65%. Regular rust prevention shall be adopted for long-term storage.
Suffix definition
B: Modified internal structure
MP: machined window brass cage
TVP: glass fiber reinforced nylon cage
UA: general structure design of paired bearing, small axial clearance bearing group
Uo: universal structure design of paired bearing, zero axial clearance bearing group
Da: double half inner ring (double row angular contact ball bearing)
TVH: glass fiber reinforced polyamide cage, steel ball guide
Maintenance method
1. When the bearing runs to a certain period (or maintenance period), remove all the bearings;
2. Soak the bearing with diesel oil or kerosene for cleaning. If there are technical conditions, it is better to open the sealing cover for cleaning;
3. After cleaning, dry the cleaning oil and check the appearance for damage;
4. Use a wooden rod (preferably a hollow tube) about 150 mm in diameter with equal inner diameter of angular contact ball bearing, and fix a bearing at one end;
5. While rapidly rotating the bearing by hand, put the other end of the wooden stick (wooden tube) on the ear or the microphone of the audio amplifier to hear the noise of the bearing rotation;
6. After fixing the bearing, move the wooden rod horizontally to check whether the bearing is worn or loose;
7. Fag bearings with serious looseness, excessive rotating noise and serious defects should be eliminated and replaced by the same type;
8. Take a bucket and melt the proper amount of grease (high-quality yellow dry oil) with gentle fire (do not overheat). Put the tested bearing into the bucket and soak it until there is no bubble overflow. Take out the bearing before the grease is cooled, and the amount of residual grease is small. After the grease is cooled, the angular contact ball bearing is taken out, and a large amount of grease remains. Determine the amount of residual grease as required.
9. Clean the grease on the outside of the bearing with soft cloth or toilet paper, and assemble the fag bearing on the pulley in its original state. The maintenance work is over.