What types of cylindrical roller bearings are there? What are their characteristics?
Cylindrical roller bearing, as the name implies, refers to a radial rolling INA bearing whose rolling element is a cylindrical roller. Cylindrical roller bearings are separable bearings, which are very convenient for installation and disassembly. Cylindrical roller bearings can withstand larger radial loads and are suitable for use in high-speed running situations. According to the number of rows of rolling elements, cylindrical roller bearings can be divided into single row, double row and multiple row cylindrical roller bearings and other different structures. Cylindrical roller bearings of different structures are also shown in the design of the rib position. The commonly used cylindrical roller bearings have the following forms.
1. Single row cylindrical roller bearings
Single row cylindrical roller bearings are separable bearings, which are easy to install and disassemble. Both rings can be tightly fitted. The revised contact line between the roller and the raceway can reduce stress concentration. Single row cylindrical roller bearings are available in N, NU, NJ, NF, NUP, NFP, NH (NJ+HJ) types.
The outer ring of the N-type bearing has no ribs, and there are ribs on both sides of the inner ring, which can allow displacement of the shaft relative to the bearing seat in the axial direction. The NU type bearing has ribs on both sides of the outer ring and no ribs on the inner ring. It can also allow displacement of the shaft in two directions between the shaft and the bearing seat. Therefore, this type of structure is suitable for use as a floating end bearing.
NJ type bearings have ribs on both sides of the outer ring and ribs on one side of the inner ring, which can bear a certain amount of unidirectional axial load. The NF type has ribs on one side of the outer ring and ribs on both sides of the inner ring, which can also bear a certain amount of unidirectional axial load. Therefore, this type of structure is suitable for use as a unidirectional axial positioning bearing.
NUP type bearings have ribs on both sides of the outer ring, one side of the inner ring has a (fixed) single rib, and the other side is a detachable flat ring, which can bear a certain amount of bidirectional axial load. NFP type bearings have a (fixed) single rib on one side of the outer ring, and a separable flat ring on the other side. There are ribs on both sides of the inner ring, which can also bear a certain amount of bidirectional axial load. Bearings of this type can limit the displacement of the shaft relative to the bearing seat in both axial directions. Therefore, it is suitable for use as a fixed end bearing.
NH type bearing is a combination of NJ type bearing and HJ type oblique retaining ring. Because the inner ring of the NUP type bearing is short, and the flat retaining ring is not fixed, it is inconvenient to use, while the NH type bearing can use the width of the entire inner ring of the NJ type bearing to maintain a tighter fit with the shaft. Moreover, NH type bearings are more convenient to install and disassemble. The NH type bearing can limit the displacement of the shaft relative to the bearing seat in both axial directions. Therefore, NH type bearings are suitable for use as fixed-end bearings.
2. Double row cylindrical roller bearings
Double-row cylindrical roller bearings have two structures: cylindrical inner bore and conical inner bore (the bearing rear code plus K). It has the advantages of compact structure, high rigidity, large carrying capacity, and small deformation after load. It is especially suitable for Machine tool spindle support. The conical inner hole can also play the role of micro-adjustment of the clearance, and can simplify the structure of the positioning device and facilitate installation and disassembly. Commonly used double row cylindrical roller bearings are NN, NNU, NNF type.
The outer ring of the NN type bearing has no ribs, and the inner ring has ribs on both sides of the inner ring. There is a middle rib in the middle, which allows the shaft to move in two directions in the axial direction relative to the bearing seat. NNU type bearings have ribs on both sides of the outer ring, with middle ribs in the middle, and no ribs on the inner ring. It can allow the shaft relative to the bearing seat to produce two directions of displacement in the axial direction. Therefore, this type of structure is suitable as a floating end bearing.
The NNF type bearing is a double-row full complement cylindrical roller bearing. It is a structural type with an outer ring with a middle rib and two inner rings with a double rib. The roller is guided by the rib of the inner ring, and the two inner rings are fixed together with a fastening ring. In addition to being able to withstand large radial loads and axial loads, this structure can also withstand overturning moments. Therefore, it is often used as a fixed-end bearing.
NNF type bearing adopts contact seal on both sides. The bearing is filled with grease. In the case of good working conditions, the sealed NNF bearing does not need to be maintained. If the bearing is exposed to water vapor or polluted environment for a long time and is running at medium or high speed, it can pass through the outer ring The lubricating oil groove and lubricating oil hole re-lubricate the bearing.
3. Four-row cylindrical roller bearings
Four-row cylindrical roller bearings are mainly used in rolling mill machinery such as cold and hot rolling mills and billeting mills. They can be divided into FC and FCD types.
The FC type bearing is composed of two outer rings and an inner ring. There are ribs on both sides of each outer ring and a middle rib in the middle, and the inner ring has no ribs. The FCD type bearing is actually a combination of two NN type bearings. FC type and FCD type bearings can allow the shaft relative to the bearing seat to produce axial displacement in two directions. Therefore, this type of structure is suitable as a floating end bearing.
Linqing Changniu (SDCN) Bearing Manufacturing Co., Ltd. was founded in 2006. It is a science, industry and trade enterprise integrating bearing design, industrial production and marketing trade. Advanced production equipment, strong technical force, and complete measurement and testing methods enable the company's products to obtain effective quality assurance. To purchase cylindrical roller bearings, search for Changniu on Mobei.com, and directly connect with the manufacturer.