Bearing form
● Inch single row deep groove ball bearing: R
● Inch single row deep groove ball bearing with flange: FR
● Metric single row deep groove ball bearings: symbols are omitted.
● Metric single row deep groove ball bearing with flange: F
● Metric single row deep groove ball bearing with specific size: Mr.
● Metric single row deep groove ball bearing with flange, specific size: MF.
● Grooved thrust bearing: FM
● Trenchless thrust bearing: F
Sealing ring; dust cover
● Contact Teflon sealing rings with retaining rings on both sides: TT
● Steel plate dust covers on both sides: ZZ
● Rubber sealing rings in contact on both sides: 2RS
lubricant
● Main grease brand logo
Martem SRL (standard grease for miniature and small bore bearings): SRL
AlvaniaNo. (standard grease for small and medium-sized bearings): AV2
Aviation caseNo. 16 (for high temperature use): AG6
Molykote 33M (for low load and low temperature): M4M
Krytox 240AC (for ultra-high temperature): K24
Isoflex Super LDS 18:SL8
Beacon 325:B32
● Major lubricating oil brand logo
Aviation Shell Lubricating Oil 12 (standard grease): AF2
Windsor lube oil L-245X:WL2
Rust inhibitor P2 100:002
Naming and basic code of SKF bearing
SKF bearing name:
A complete bearer code consists of a basic code plus one or more supplementary codes. Basic code: used to indicate the type of bearing, the basic design of bearing and the overall dimensions of bearing. Supplementary code: bearing parts and variants with different structures or other characteristics from the basic design.
Basic code of SKF bearing:
All standard bearings of SKF have specific basic models, usually three, four or five numbers, or a combination of letters and numbers. The first number or the first letter or letter combination indicates the bearing type; The last two digits determine the ISO size series; The first number represents the width or height series (dimension B, T or H respectively), and the second number represents the diameter series (dimension D). The last two digits of the basic model are the size code of the bearing; Multiply by 5 to get the inner diameter in millimeters. But there are some exceptions, as follows:
1. In some cases, the number indicating the bearing type and the first number indicating the size series are omitted. For example: 6(0)208-2Z (0)3209 A
2. For bearings with an inner diameter less than or equal to 10 mm or greater than or equal to 500 mm, the inner diameter is usually directly expressed in millimeters without codes. Dimensions are separated from the rest of the bearing model by diagonal lines, such as 6 18/8 (d = 8mm) or 6 18/530ma (d = 530mm).
3. Bearings with inner diameters of 10, 12, 15 and 17mm have the following dimension code marks: 00 =10mm01=12mm 02 =/.
4. For some smaller bearings with inner diameter less than 10 mm, such as deep groove, self-aligning and angular contact ball bearings, the inner diameter is also expressed in millimeters (no code), but it is not separated from series models by diagonal lines, such as 629 or 129 (d = 9 mm).
5. The bearing inner diameter that deviates from the standard inner diameter is always expressed in millimeters, with at most three decimal places, and there is no code. The internal diameter mark is a part of the basic model, separated from the basic model by diagonal lines, for example, 6202/15875 (d =15875 mm).
Class 0: Double row angular contact ball bearing (usually omitted) Example: (0)3204 A
1 class: self-aligning ball bearing: Example: 120 1 ETN9.
Category 2: spherical roller bearings and spherical roller thrust bearings: for example: 22209 E 29328 E.
Class 3: tapered roller bearing: 320 16 X/Q
Class 4: Double row deep groove ball bearing Example: 4206 ATN9
Category V: thrust ball bearing: 5 1 100.
Category 6: deep groove ball bearings: 62 13-2Z.
Category 7: angular contact ball bearings Example: 7305 BECBM
Class VIII: cylindrical roller thrust bearing: 81111TN.
Class N: The second letter or sometimes the third letter of cylindrical roller bearings is used to determine the flange structure. For example, the model of NJ, NU and NUP double-row or multi-row cylindrical roller bearings always starts with NN.
For example: NU 23 17 ECJ
Class c: carbohydrate bearing C 2205
QJ class: four-point contact ball bearing example: QJ 2 17 MA.
NSK carries the meaning of pre-code and post-code.
prefix code
F—— Deep groove ball bearing with flange outer ring (applicable to inner diameter
HR—— High-load tapered roller bearing, for example, HR 30207 J.
MF-Deep groove ball bearing with flange outer ring of specific size (suitable for inner diameter
MR—— deep groove ball bearing with specific size (applicable to inner diameter)
Postcode
1, internal structure
Calcium solid brass cage
CD- with stamping bracket
High-load self-aligning roller bearing
E- high load cylindrical roller bearing
H- high load thrust self-aligning roller bearing
2. Materials
G—— Ring, and the rolling elements are carburized steel.
H—— Ring, and the rolling element is stainless steel.
3. birdcage
M- copper alloy solid cage
T- synthetic resin cage
W-punching cage
No cage
4, sealing ring, dust cover
Zs z-dust cover with steel plate on one side
Zzzz-dust cover with steel plates on both sides.
D, DU—— One side has a contact rubber sealing ring.
DD, DDU- Contact rubber sealing rings on both sides
V- one side has a non-contact rubber sealing ring.
Vv- one side is provided with a non-contact rubber sealing ring.
5, ferrule shape
K—— Tapered hole with taper of 1: 12.
K30- Tapered hole with a taper of 1: 30.
E—— There is a gap or oil hole on the ferrule.
E4—— There are oil grooves and oil holes in the outer ring.
N—— There is a stop groove on the outer diameter of the outer ring.
NR—— The outer diameter of the outer ring has a stop groove and a stop ring.
6. Accessories and washers
Db- Paired back-to-back installation
DF- Face-to-face installation in pairs
Dt- series and paired installation
+k-outer ring with washer
+l-inner ring with washer
+KL-inner ring and outer ring are padded.
H—— structural code of fastening sleeve
AH—— Structure code for dismantling sleeve.
HJ——L structure code of L-shaped flange ring
7. Special specifications
X26—— The service temperature shall be limited below 150℃.
X28—— The service temperature is limited below 200℃
X29—— The service temperature is limited below 250℃
S 1 1- Self-aligning roller bearing, the service temperature is limited below 200℃.
Accuracy and grade of bearings
The accuracy of rolling bearings can be divided into (main) dimensional accuracy and rotational accuracy. The accuracy grade has been standardized and divided into five grades: P0, P6, P5, P4 and P2.
The accuracy gradually increases from level 0, which is generally sufficient, but when used in the conditions or occasions shown in table 1, the accuracy of level 5 or higher is required.
Although the above precision grades are based on ISO standards, they have different names in national standards.
It is suitable for the comparison of precision grades of various bearing types and national standards.
Dimensional accuracy (items related to shaft and housing installation)
1, allowable deviation of inner diameter, outer diameter, width and assembly width
2. Allowable deviation between the last contact diameter and the last contact diameter of the roller group.
3. Allowable limit value of chamfer size
4. Allowable variation of width
Rotation accuracy (items related to the runout of the rotating body)
1, allowable radial runout and axial runout of inner ring and outer ring.
2. Allowable lateral runout of inner ring
3. Allowable deviation of inclination of outer diameter surface
4. Allowable deviation of raceway thickness of thrust bearing
5. Allowable deviation and variation of conical hole
Deep groove ball bearing is the most commonly used rolling bearing. It is simple in structure and convenient to use. It is mainly used to bear radial load, but when the radial clearance of the bearing increases, it has certain performance of angular contact ball bearing and can bear combined radial and axial load. When the rotating speed is high and it is not suitable to use thrust ball bearings, they can also be used to bear pure axial load. Compared with other types of bearings of the same size, this bearing has small friction coefficient and high limit speed. But it is not resistant to impact and is not suitable for bearing heavy loads.
After the deep groove ball bearing is installed on the shaft, it can limit the axial displacement of the shaft or shell in two directions within the axial clearance range of the bearing, so it can be axially positioned in two directions. In addition, this bearing also has a certain self-aligning ability. When it is inclined 2 ′ ~10 ′ relative to the bearing seat hole, it can still work normally, but it has certain influence on the bearing life.
The cages of deep groove ball bearings are mostly steel plate stamping wave cages, and large bearings are mostly machined metal solid cages.
Deep groove ball bearings are widely used in automobiles, tractors, machine tools, motors, water pumps, agricultural machinery, textile machinery and so on.
The raceway of the outer ring of the self-aligning ball bearing is spherical and has self-aligning performance, so it can automatically adjust the misalignment of the shaft caused by the deflection or misalignment of the shaft or shell.
Product features:
It mainly bears radial load and can bear smaller axial load at the same time. The axial displacement of the shaft (shell) is limited within the clearance limit, which has self-aligning performance, allowing the internal and external parts to work normally under the condition of small relative inclination, and is suitable for the parts where the concentricity of the bearing seat hole cannot be strictly guaranteed.
Main applications
Mechanical and electrical equipment ◆ Plastic machinery
Office equipment ◆ Transmission shaft of textile machinery
Medical equipment ◆ Fitness and sports equipment
Self-aligning ball bearing is a double-row ball bearing with spherical outer ring raceway and inner ring raceway, which has self-aligning performance. It is mainly used to bear radial load and a small amount of axial load, but generally it cannot bear pure axial load, and its limit speed is lower than that of deep groove ball bearings. This kind of bearing is mostly used in the parts where the double bearing shaft is easy to bend under the load and the holes of the double bearing seat can't ensure strict coaxiality, but the relative inclination between the center line of the inner ring and the center line of the outer ring should not exceed 3 degrees.
Cylindrical roller bearing is a separate bearing, which is very convenient to install and disassemble. Cylindrical roller bearings are divided into single row, double row and four rows.
Cylindrical roller bearings can be divided into single row, double row and multi-row cylindrical roller bearings according to the number of rows of rolling elements used in bearings. Among them, single-row cylindrical roller bearings with cages are widely used. In addition, there are cylindrical roller bearings with other structures such as single row or double row full rollers.
Single-row cylindrical roller bearings can be divided into N type, NU type, NJ type, NF type, NUP type and so on. Cylindrical roller bearings can bear large radial load capacity, and can also bear certain unidirectional or bidirectional axial load according to the structure of annular flange.
NN-type and NNU-type double-row cylindrical roller bearings are compact in structure, strong in rigidity, large in bearing capacity and small in deformation after loading, and are mostly used to support the spindle of machine tools.
FC, FCD and FCDP four-row cylindrical roller bearings can bear large radial load and are mostly used in heavy machinery such as rolling mills.
Cylindrical roller bearings are mainly used in motors, machine tools, petroleum, rolling mill loading and unloading machinery and various industrial machinery.
Single-row cylindrical roller bearing is a separable bearing, which is convenient to install and disassemble. The two rings can be closely matched, and the corrected contact line between the roller and the raceway can reduce stress concentration.
Double-row cylindrical roller bearing belongs to sliding bearing, and its separability makes installation and disassembly very convenient. Both ferrules can be tightly fitted. Double-row cylindrical roller bearings are almost not allowed to have inclination angles.
Single-row cylindrical roller bearings usually only bear radial force. Compared with ball bearings of the same size, the radial bearing capacity is increased by 1.5-3 times, and it has good rigidity and impact resistance. It is especially suitable for rigid support, supporting short shafts, shafts with axial displacement caused by thermal elongation, and machine accessories that need separate bearings for installation and disassembly. Mainly used for large motors, machine tool spindles, engine front and rear support shafts, train and bus trunk shaft support, diesel engine crankshaft, automobile tractor gearbox, etc. NN30 series tapered cylindrical roller bearings are mainly used as radial supports for machine tool spindles, NNU49 series double-row cylindrical roller bearings and N 19 and N 10 single-row cylindrical roller bearings.
Self-aligning roller bearing is equipped with a drum roller bearing between the inner ring with two raceways and the outer ring with spherical raceway. The curvature center of the raceway surface of the outer ring is consistent with the bearing center, so it has the same self-aligning function as the self-aligning ball bearing. When the important official and the shell are bent, it can be automatically adjusted without increasing the bearing burden. Self-aligning roller bearing can bear radial load and axial load in two directions. Large radial load capacity, suitable for heavy load and impact load. Bearings with tapered holes in the inner ring can be installed directly. Or mounted on a cylindrical shaft using a fastening sleeve and a dismounting cylinder. The cage adopts steel plate stamping cage, polyamide forming cage and copper alloy turning cage.
Self-aligning roller bearing can bear large radial load and certain axial load. The outer raceway of this bearing is spherical, so it has self-aligning performance. When the relative inclination of the center line of the inner ring and the center line of the outer ring is less than 1 ~ 2.5 due to the bending or inclination of important officials, the bearing can still work.
There are two kinds of inner holes of self-aligning roller bearings: cylindrical and conical. The taper of the tapered inner hole is 1: 1 2 or 1: 30. In order to enhance the lubrication performance of the bearing, an annular oil groove and three evenly distributed oil holes are machined on the outer ring of the bearing.
Self-aligning roller bearings are suitable for bearing heavy load and impact load, and are widely used in metallurgy, rolling mill, mining, petroleum, paper making, cement, sugar making and other industries.
Needle roller bearings are roller bearings with cylindrical rollers, which are thin and long relative to the diameter. This kind of roller is called needle roller. Although its cross section is very small, the bearing still has high bearing capacity, so it is especially suitable for occasions with limited radial space.
The contour surface of the needle roller shrinks slightly near the end face. The result of contact correction between needle roller and raceway line can avoid destructive edge stress. In addition to the bearings listed in the catalogue that can be used in general projects, such as: open-type stamped outer ring needle bearing (1), closed-type stamped outer ring needle bearing (2), needle bearing with inner ring (3) and needle bearing without inner ring (4), SKF can also supply various types of needle bearings, including: 1, needle cage assembly 2 and needle cage assembly 2.
Punched outer ring needle roller bearing is a kind of thin punched outer ring needle roller bearing. Its main features are low section height and high bearing capacity. It is mainly used for bearing configuration with compact structure and low price, and the inner hole of the bearing box cannot be used as the raceway of the needle roller cage assembly. Bearings and bearing housings shall be installed in an interference fit manner. If the axial positioning functions such as box shoulder and retaining ring can be omitted, the inner hole of bearing box can be made extremely simple and economical.
Needle roller bearings with a stamped outer ring at the shaft end have two open faces (1) and one closed face (2). The base end face of the closed stamping outer ring can bear little axial guiding force.
Needle roller bearings with stamped outer rings usually do not have inner rings. When important official neck cannot be hardened and ground, the inner ring listed in the table can be used. The hardened steel plate outer ring of the stamped outer ring needle roller bearing is inseparable from the needle roller cage assembly. The free space for storing lubricant can prolong the interval of supplementary lubrication. Bearings are usually designed in a single row. However, bearings with wider specifications such as 1522, 1622, 2030, 2538 and 3038 are not included, and they are equipped with two needle roller cage assemblies. There are lubricating oil holes in the outer ring of the bearing. According to user's requirements, all single-row stamped outer ring needle roller bearings with shaft diameter greater than or equal to 7mm can be equipped with outer rings with lubricating oil holes (code suffix AS 1).
Needle roll bearing with oil seal stam outer ring
When the oil seal cannot be installed due to space limitation, needle bearings (3 to 5) with oil seal stamped outer rings at the open end or the closed end can be provided. This kind of bearing is equipped with polyurethane or synthetic rubber friction oil seal, and filled with lithium-based grease with good antirust performance. The applicable working temperature is -20 to+100℃.
The inner ring of the bearing with oil seal is wider than the outer ring by 1mm, so that the bearing can work well when the crankshaft is slightly displaced relative to the bearing box to avoid bearing pollution. The bearing inner ring also has lubrication holes, which can be supplemented by the outer ring or the inner ring according to the needs of bearing configuration.
The outer spherical bearing is best used in situations where simple equipment and parts are needed, such as agricultural machinery, transportation systems or construction machinery. The outer spherical bearing unit consists of double-sided sealed spherical outer ring deep groove ball bearing and gray cast iron or stamped steel plate bearing seat.
External spherical bearings are mainly used to bear combined radial and axial loads, mainly radial loads. Generally, it is not suitable for bearing axial load alone. This bearing can be equipped with an inner ring (with all rollers and cages) and an outer ring respectively. This kind of bearing does not allow the shaft to tilt relative to the housing, which will produce additional axial force under radial load. The axial clearance of this kind of bearing has a great relationship with whether the bearing can work normally. When the axial clearance is too small, the temperature rise is higher. When the axial clearance is large, the bearing is easy to be damaged. Therefore, special attention should be paid to adjusting the axial clearance of the bearing during installation and operation, and pre-interference installation can be carried out when necessary to increase the stiffness of the bearing.
Linear bearing is a low-cost linear motion system for infinite travel and cylindrical shafts. Because the bearing ball is in point contact with the shaft, the use load is small. The steel ball rotates with the minimum friction resistance, so that smooth motion with high precision can be obtained.
Linear bearing is widely used in electronic equipment, tensile testing machine, digital three-dimensional coordinate measuring equipment and other precision equipment, as well as sliding parts of industrial machinery such as multi-spindle machine tools, punching machines, tool grinders, automatic gas cutting machines, printers, card sorting machines and food packaging machines.
* Lubrication and friction
* grease lubrication
Linear bearings are injected with anticorrosive oil. If lubricating with grease, remove the anticorrosive oil with kerosene or organic solvent first, and then add the grease after drying.
It is recommended to use lithium soap grease with viscosity mark N0.2.
* oil lubrication
When lubricating with oil, it is not necessary to remove the anticorrosive oil. According to the temperature change, lubricating oil with ISO viscosity grade VG 15- 100 can be selected. Shaft lubrication can be provided through the oil supply pipe or the oil hole on the outer bearing seat. Because the sealing ring will scrape off the lubricating oil, oil lubrication is not suitable for non-porous bearings with sealing rings.
* Friction coefficient
The energy loss caused by friction is very small. When the moving speed is less than 60m/min, the temperature effect can be ignored. Friction can be obtained by the following equation: F=ц. Friction (Newton)
*: sealing resistance (2 ~ 5n) P: external load (n)
ц: coefficient of friction
* Installation
* Fit clearance
It is recommended to use the matching tolerance of bearing seat hole and optical axis diameter. Normally, the bearing can't be pre-tightened, but it can be highly accurate and lightly pre-tightened. However, the negative diameter tolerance should not exceed the data in the table. Bearing box and fit clearance between shaft and bearing.
Precautions during installation:
When installing the linear bearing into the bearing seat, auxiliary work should be used to avoid directly hitting the end face or sealing ring. Bearings shall be used for uniform introduction. Gently tap the optical axis into the linear bearing with the buffer plate, and the center lines of the shaft and bearing must be aligned. If the shaft is inserted obliquely, the ball may fall off or the cage may be deformed. The external load that damages linear bearing should be evenly distributed on the whole bearing, especially when bearing instantaneous load, two or more bearings should be used. Linear bearing does not bear the rotating load, otherwise it may lead to an accident.
Thrust cylindrical roller bearing is a separate bearing, which can only bear unidirectional axial load and slight impact, and can limit the axial displacement of the shaft (or shell) in one direction, so it can be used for unidirectional axial positioning. But its bearing capacity is much greater than that of thrust ball bearings. When the roller rolls, due to the different linear velocities at both ends of the roller, the roller inevitably slides on the raceway of the ring. Therefore, the limit speed of this kind of bearing is lower than that of thrust ball bearing, and it is usually only suitable for low-speed operation.
The standard design of thrust cylindrical roller bearing adopts metal solid cage machined by lathe, and other types or materials of cages can also be used according to users' requirements.
Thrust tapered roller bearing can only bear unidirectional axial load, which limits the unidirectional axial displacement of the bearing, so it can be used for unidirectional axial positioning. Compared with the thrust cylindrical roller bearing, the bearing capacity is large, the relative sliding is small, but the limit speed is low.
Thrust cylindrical roller bearings are mainly used in heavy machine tools, high-power marine gear boxes, oil rigs, vertical motors and other machinery.
The thrust ball bearing consists of a row of steel balls (with cages), a shaft ring (tightly fitted with the shaft) and a seat ring (tightly fitted with the bearing seat hole and with a gap from the shaft), and the steel balls rotate between the shaft ring and the seat ring. It can only bear axial load in one direction, but not radial load. Because the axial load is evenly distributed on each steel ball, the bearing capacity is large; However, when working, the temperature rise is large and the allowable limit speed is low.
Thrust ball bearing can not limit the radial movement of shaft or shell, but can limit the axial movement of shaft and shell in one direction. Therefore, this kind of bearing is usually used in combination with deep groove ball bearings.
During installation, the axis of the shaft and the bearing seat hole must be concentric, otherwise the bearing will be damaged prematurely due to stress concentration. In order to eliminate this bad phenomenon, a radial clearance of 0.5 ~ 1 mm can be left between the outer diameter of the seat ring and the hole of the housing. The center line of the shaft should be perpendicular to the bearing surface of the shell, and the shaft is not allowed to tilt and bend, otherwise the bearing will be damaged prematurely due to uneven load distribution. In order to eliminate the inclination of the bearing shaft, the bearing surface of the seat ring can be padded with elastic materials, such as oil-resistant rubber and leather. Or a thrust ball bearing with a spherical seat can be used.
Thrust ball bearing is a separate bearing, which can be divided into one-way thrust ball bearing and two-way thrust ball bearing according to its structural form. One-way thrust ball bearing can bear axial load in one direction, and two-way thrust ball bearing can bear axial load in two directions. None of them can bear radial load. Thrust ball bearings also have a padded structure. Because the installation surface of the pad is spherical, the bearing has self-aligning performance, which can reduce the influence of installation error. Thrust ball bearings are mainly used in automobile, machine tool and other industries.
Angular contact ball bearings can bear radial and axial loads. Can work at a higher speed. The larger the contact angle, the higher the axial bearing capacity. Generally, the contact angle of high-precision high-speed bearings is 15 degrees. Under the axial force, the contact angle will increase. Single row angular contact ball bearing can only bear axial load in one direction, and when it bears radial load, it will cause additional axial force. And can only limit the axial displacement of the shaft or the housing in one direction. If installed in pairs, make the outer rings of a pair of bearings face each other, that is, the wide end faces the wide end face and the narrow end faces the narrow end face. In this way, additional axial force can be avoided, and the shaft or housing can be limited within the axial clearance range in two directions.
Angular contact ball bearings can bear both radial load and axial load-combined load, because the raceway of its inner and outer rings can be relatively displaced on the horizontal axis (single row angular contact ball bearings can only bear unidirectional axial load, so they are generally installed in pairs). The cage is made of brass, synthetic resin, etc. , depending on the bearing form and service conditions.
There are several types of angular contact ball bearings: 7000C (∝ = 15), 7000a (∝ = 25) and 7000b (∝ = 40). This kind of bearing is locked on the outer ring, and the inner and outer rings can not be separated generally, and can bear the combined load of radial and axial direction and the axial load in one direction. The ability to bear axial load is determined by the contact angle. The greater the contact angle, the higher the ability to bear axial load. The bearing can limit the axial displacement of the shaft or housing in one direction.
Tapered roller bearings mainly bear combined radial and axial loads. The bearing capacity depends on the raceway angle of the outer ring, and the greater the angle, the greater the bearing capacity. This kind of bearing belongs to separate bearing, which is divided into single row, double row and four rows of tapered roller bearings according to the number of rows of rolling elements in the bearing. The clearance of single row tapered roller bearings needs to be adjusted by users during installation; The clearance of double-row and four-row tapered roller bearings has been given according to the user's requirements at the factory, and it does not need to be adjusted by the user.
Tapered roller bearing has a conical inner ring and an outer ring raceway, between which a tapered roller is arranged. The projection lines of all conical surfaces intersect at the same point on the bearing shaft. This design makes tapered roller bearings especially suitable for bearing compound (radial and axial) loads. The axial bearing capacity of bearings is mostly determined by contact angle α; The greater the angle α, the higher the axial bearing capacity. The angle is expressed by the calculation coefficient e; The greater the e value, the greater the contact angle and the greater the applicability of the bearing to bear axial load.
Tapered roller bearings are usually separated, that is, the tapered inner ring assembly composed of belt roller inner ring and cage assembly can be installed separately from the tapered outer ring (outer ring).
Tapered roller bearings mainly bear combined radial and axial loads. The bearing capacity depends on the raceway angle of the outer ring, and the greater the angle, the greater the bearing capacity. This kind of bearing belongs to separate bearing, which is divided into single row, double row and four rows of tapered roller bearings according to the number of rows of rolling elements in the bearing. The clearance of single row tapered roller bearings needs to be adjusted by users during installation; The clearance of double-row and four-row tapered roller bearings has been given according to the user's requirements at the factory, and it does not need to be adjusted by the user.
Tapered roller bearings are widely used in automobile, rolling mill, mining, metallurgy, plastic machinery and other industries.