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). This type of bearing has the advantages of compact structure, high rigidity, large carrying capacity, and small deformation after being loaded. 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 have the following forms:NN, NNU 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, and there is a middle rib in the middle. It can allow the shaft relative to the bearing seat to produce two directions of displacement in the axial direction.
NNU type bearings have ribs on both sides of the outer ring and 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 cages of this type of bearing mostly use car-made solid cages.
NNF type
The NNF type bearing is a double row full complement cylindrical roller bearing. The bearing consists of an outer ring with a central 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 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. The working temperature of the grease is -50°C to +110°C. However, due to the limitation of the sealing material, the working temperature of the bearing is limited to between -40°C and +80°C. 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 be adjusted through the lubricating oil groove and lubricating hole on the outer ring. The bearings are relubricated.
NN30 seriesdouble row cylindrical roller bearings are the most commonly used bearings for machine tool spindles. This type of bearing can withstand large radial loads. Because the inner and outer rings are separable, they cannot bear axial loads, allowing axial movement. Therefore, on machine tools, it is often used in combination with bidirectional thrust angular contact ball bearings, angular contact ball bearings, tapered roller bearings, and thrust ball bearings to form the support of the machine spindle.
Features of Cylindrical Roller Bearings:
1. The roller and the raceway are in line contact or under-line contact, with large radial bearing capacity, suitable for bearing heavy loads and impact loads.
2. The friction coefficient is small, suitable for high speed, and the limit speed is close to the deep groove ball bearing.
3. The N type and NU type can move axially, can adapt to the change of the relative position of the shaft and the housing caused by thermal expansion or installation error, and can be used as a free end support.
4. The processing requirements for the shaft or the seat hole are relatively high. After the bearing is installed, the relative deflection of the outer ring axis should be strictly controlled to avoid contact stress concentration.
5. The inner ring or outer ring can be separated for easy installation and disassembly.
The main purpose:
Large and medium-sized electric motors, rolling stock, machine tool spindles, internal combustion engines, generators, gas turbines, gearboxes, rolling mills, vibrating screens, lifting and transporting machinery, etc.
NN3032KW33P5 Double-row cylindrical roller bearings
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