Performance and application collection of various bearings on agricultural machinery
The world of bearings from the perspective of numbersDimensions range from 2mm to 6m
Bearings vary in size from small to large. The world's smallest "micro bearing" size is 0.6mm inner diameter × Outer diameter 2.0mm × The thickness is 0.8mm, which is used for micro motor. The large bearing, with an outer diameter of 6 meters and a weight of more than 15 tons, is used in large shield machines for tunnel excavation. This shield machine is used when excavating a cross sea tunnel under the Dover strait connecting Britain and France, including this large bearing.
400000 rpm
The dental drill (commonly known as dental mobile phone) used by dentists is equipped with bearings that can rotate at an ultra-high speed. These are two 3.0mm inner diameter × Outer diameter 6.0mm × Ultra precision bearing with width of 2mm and steel ball diameter of 1.0mm. They can rotate at an amazing speed of "400000 revolutions per minute", which greatly reduces the vibration of dental phones, thus greatly reducing the pain of patients during treatment.
The speed of the steel ball is 160 meters per second
The main shaft bearing is used for the jet engine V2500 of international airliners. The rolling speed of its rolling element is 160 meters per second, equivalent to 580 kilometers per hour. It is precisely because of the use of high-performance high-speed bearings that the engine can run safely for a long time and send passengers safely all over the world.
Amplitude below 100 nm
"The accuracy of machinery depends on the rotation accuracy of bearings", which is no exaggeration. Both ends of the rotating shaft are supported by two bearings. If the shaking of the shaft center is large, the mechanical performance cannot be improved. Metal processing wechat, good content, worthy of attention. The amplitude of the axis of the computer external storage equipment with ultra precision bearings, namely "hard disk", is less than 100 nm (1 nm = 1 / 1000000 mm). The key to achieving such ultra-high precision is the accuracy of rolling elements such as "steel ball" and "roller".
It can work in space for 15 years
The development of the universe is also inseparable from bearings. Weather forecasts, satellite radio and television signals, car satellite positioning information, etc. are provided by man-made satellites flying around the earth. The satellite is equipped with a gyroscope to maintain the attitude and heading of the satellite, and the gyroscope is equipped with ultra precision bearings. This kind of bearing can work continuously in space for 15 years.
A world of 253 degrees below zero to 500 degrees above zero
The bearing in the liquid fuel pump of aerospace rocket is the bearing with the lowest temperature. The bearing works in liquid hydrogen at minus 253 ℃. The bearings used in high temperature environment are typical of the special high-performance bearings in medical CT scanners. In the X-ray vacuum tube with the temperature up to 300 to 500 ℃, the bearing can also operate continuously and play a role in ensuring our health.
The world of bearings from the perspective of shape
"Self aligning ball bearing"
The 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 outer ring raceway surface is consistent with the bearing center, so it has the same centering function as the automatic centering ball bearing. Metal processing wechat, good content, worthy of attention. In case of deflection of shaft and shell, the load and axial load in two directions can be adjusted automatically. Large radial load capacity, suitable for heavy load and impact load. The inner diameter of the inner ring is a bearing with tapered hole, which can be installed directly. Or install it on the cylindrical shaft with tightening sleeve and disassembly cylinder. The cage uses steel plate stamping cage, polyamide forming cage and copper alloy car cage.
Needle roller bearing
Solid needle roller bearing
The basic structure of the bearing with inner ring is the same as that of Nu cylindrical roller bearing, but due to the use of needle roller, the volume can be reduced and can bear large radial load. For the bearing without inner ring, the mounting surface of the shaft with appropriate accuracy and hardness should be used as the raceway surface.
Thrust needle roller bearing
The release bearing is composed of a raceway ring, a needle roller and a cage assembly, and can be arbitrarily combined with a stamping thin raceway ring (W) or a cutting thick raceway ring (WS). The non separable bearing is an integral bearing composed of precision stamped raceway ring, needle roller and cage components. This kind of bearing can bear unidirectional axial load. The small occupied space is conducive to the compact design of the machine. Most of them only use the needle roller and cage components, and the mounting surface of the shaft and housing is used as the raceway surface.
Tapered roller bearing
This type of bearing is equipped with round platform shaped rollers, which are guided by the large retaining edge of the inner ring. In the design, the apex of each conical surface of inner race surface, outer race surface and roller rolling surface intersects at a point on the bearing centerline. Single row bearing can bear radial load and unidirectional axial load, and double row bearing can bear radial load and bidirectional axial load. It is suitable for bearing heavy load and impact load.
Cylindrical roller bearing
According to the number of columns of rolling elements installed in bearings, cylindrical roller bearings can be divided into single row, double row and multi row cylindrical roller bearings. The single row cylindrical roller bearing with cage is widely used. In addition, there are cylindrical roller bearings with other structures such as single row or double row full loaded rollers.
Single row cylindrical roller bearings can be divided into N type, nu type, NJ type, NF type and NUP type according to the different retaining edges of the ferrule. Cylindrical roller bearing can bear large radial load. According to the structure of ring retaining edge, it can also bear certain unidirectional or bidirectional axial load. NN and NNU double row cylindrical roller bearings have compact structure, strong rigidity, large bearing capacity and small deformation after loading. They are mostly used for the support of machine tool spindle. 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.
"Self aligning roller bearing"
This kind of bearing is equipped with spherical rollers between the outer ring of spherical raceway and the inner ring of double raceway. According to different internal structures, it is divided into four types: R, Rh, RHA and Sr. Since the arc center of the outer race raceway is consistent with the bearing center and has centering performance, the misalignment of the axis caused by the deflection or non concentricity of the shaft or housing can be automatically adjusted. It can bear radial load and bidirectional axial load. In particular, the radial load capacity is large, which is suitable for bearing heavy load and impact load. Metal processing wechat, good content, worthy of attention. Tapered bore bearings can be assembled and disassembled on the shaft by using fasteners or withdrawal sleeves. Self aligning roller bearings can bear large radial load and certain axial load at the same time. The outer race raceway of this kind of bearing is spherical, so it has centering performance. When the shaft is bent or tilted by force, the relative inclination between the inner race center line and the outer race center line is no more than 1 ° ~ 2.5 °, the bearing can still work.
Thrust roller bearing
Thrust roller bearings include thrust self-aligning roller bearings, thrust cylindrical roller bearings and thrust tapered roller bearings. The thrust self-aligning roller bearing can bear both axial and radial loads, but the radial load shall not exceed 55% of the axial load. Another important feature of this kind of bearing is its self-aligning performance, so it is not very sensitive to different centrality and shaft deflection. As long as the loads P and P. If it does not exceed 0.05c and the shaft ring rotates, a certain range of centering angle is allowed for the bearing. Small values are applicable to large bearings, and the allowable centering angle will decrease when the load increases.
"Outer spherical bearing"
Outer spherical bearings are preferred for applications requiring simple equipment and parts, such as agricultural machinery, transportation system or construction machinery.
It is mainly used to bear the combined radial and axial load dominated by radial load. Generally, it is not suitable to bear the axial load alone. This kind of bearing can be installed with inner ring (with full set of rollers and retainer) and outer ring respectively. This kind of bearing does not allow the shaft to tilt relative to the housing, and additional axial force will be generated under the appointment of 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 high; When the axial clearance is large, the bearing is easy to be damaged. Therefore, during installation and operation, special attention should be paid to adjusting the axial clearance of the bearing. If necessary, pre interference installation can be carried out to increase the rigidity of the bearing.
"Plain bearing"
There are two types of plain bearings: lubricated and self-lubricating. Plain bearing is a sliding bearing with special structure. Its structure is simpler than that of rolling bearing. It is mainly composed of an outer ring with inner sphere, which can bear large load. According to the inner ring with outer sphere and its different types and structures, it can bear radial load, axial load or combined load with radial and axial at the same time. It is generally used for low-speed swing motion (i.e. angular motion, or inclined motion (i.e. centering motion) within a certain angle range. Because the sliding surface is spherical motion), it can still work normally when the non concentricity between the support shaft and the shaft shell hole is large.
Linear bearing
Linear motion ball bearings are mainly used in the linear reciprocating parts of mechanical equipment. They have the advantages of small friction, flexible movement and convenient maintenance and replacement. It is widely used in textile machinery, printing machinery, medical machinery, precision machine tools, electrical cutting machines and automatic recorders.
Angular contact bearing
Angular contact ball bearing can bear radial load and axial load at the same time, or with pure axial load, and the limit speed is higher. The ability of this kind of bearing to bear axial load is determined by the contact angle. With large contact angle, it has high ability to bear axial load.
