cylindrical roller bearings

cylindrical roller and raceway for line contact bearings. Large load capacity, mainly to bear radial load. The friction between the rolling body and the retaining edge of the ferrule is small, and it is suitable for high-speed rotation. According to the ring with or without ribs, it can be divided into NU, NJ, NUP, N, NF and other single-row cylindrical roller bearings, and NNU, NN and other double-row cylindrical roller bearings. The bearing is a structure in which the inner ring and the outer ring can be separated.
The inner ring or outer ring of cylindrical roller bearings without rib, the inner ring and outer ring can make relative movement to the axial direction, so it can be used as a free end bearing. A cylindrical roller bearing with a double rib on one side of the inner ring and the outer ring, and a single rib on the other side of the ring, can withstand a certain degree of axial load in one direction. Generally use steel plate stamping cage, or copper alloy car solid cage. But there is also a part of the use of polyamide forming cage.
Features
1. Roller and raceway for line contact or repair line contact, radial bearing capacity, suitable for heavy load and impact load.
2. The friction coefficient is small, suitable for high speed, and the limit speed is close to deep groove ball bearings.
3. N type and NU type can move axially, can adapt to the change of the relative position of the shaft and the shell caused by thermal expansion or installation error, and can be used as free end support.
4. The processing requirements for the shaft or seat hole are 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 removal [1].
Product Features
The cylindrical roller is in line contact with the raceway, and the radial load capacity is large. It is not only suitable for bearing heavy load and impact load, but also suitable for high-speed rotation.
Cylindrical roller bearing raceway and rolling body is geometric shape. After the improved design, it has higher bearing capacity. The new structure design of the rib and roller end face not only improves the axial bearing capacity of the bearing, but also improves the lubrication conditions of the contact area between the roller end face and the rib, and improves the bearing performance.
Structure
1. The outer ring has no rib N0000 type and the inner ring has no rib NU0000 type. The cylindrical roller bearing can accept large radial load, high limit speed, does not bind the axial displacement of the shaft or housing, and cannot accept axial load.
Bearing structure type
2. The inner and outer rings of cylindrical roller bearings with ribs NJ0000 type and NF0000 type bearings can restrain the axial displacement of the shaft or the housing in one direction, and can accept a small one-way axial load. NU0000 HJ0000, NJ0000 HJ0000 and NUP0000 bearings can restrain the axial displacement of the shaft or housing in both directions within the axial clearance field of imported bearings, and can accept small bidirectional axial load [2].
Cylindrical roller bearing category
Cylindrical roller bearings are separate bearings, installation and removal is very convenient. Cylindrical roller bearings can withstand large radial loads and are suitable for use at high speeds.
four-row cylindrical roller
This type of bearing allows the angle error (inclination) between the inner ring axis and the outer ring axis to be small, only 2 & prime;~ 4 & prime;. Therefore, the machining accuracy of the shaft and the bearing seat is relatively high. Otherwise, uneven load or stress concentration will easily occur at the contact part of the raceway. However, the stress concentration can be reduced by modifying the contact busbar of the roller or raceway.
Cylindrical roller bearings can be divided into single-row, double-row and multi-row cylindrical roller bearings and other different structures according to the number of columns of rolling elements. Different structural bearings are also shown in the design of the position of the rib. The commonly used cylindrical roller bearings have the following forms:
Single-row cylindrical roller bearings: Single-row cylindrical roller bearings are separable bearings, easy to install and remove, two rings can be used tight fit, the correction of the contact line between the roller and the raceway can reduce stress concentration.
Double row cylindrical roller bearings: double row cylindrical roller bearings are traveling bearings, its separability makes the installation and removal is very convenient. Both ferrules can be a tight fit. Double row cylindrical roller bearings are almost not allowed to have a tilt angle.
single row bearing
N, NU type
Single row cylindrical roller bearing
The outer ring of the N-type bearing has no rib, and the two sides of the inner ring have ribs. Displacement between the shaft relative to the bearing housing may be allowed in both axial directions. NU type bearing outer ring has ribs on both sides, and the inner ring has no ribs. It is also possible to allow a displacement between the shaft relative to the bearing seat in both axial directions. Therefore, this type of structure is suitable for use as a free-running end bearing.
NJ, NF type
There are ribs on both sides of the outer ring of NJ type bearing, and there are ribs on one side of the inner ring. Can withstand a certain amount of unidirectional axial load. The outer ring of NF type has a rib on one side and a rib on both sides of the inner ring. It 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, NFP
The NUP type bearing has a rib on both sides of the outer ring, one side of the inner ring with a (fixed) single rib, and the other side is a detachable flat retaining ring. Can withstand a certain amount of two-way axial load.
Type NFP bearings have a (fixed) single rib on one side of the outer ring and a detachable flat ring on the other side, with ribs on both sides of the inner ring. It can also bear a certain amount of bidirectional axial load. This kind of structure bearing can limit the displacement of the shaft relative to the bearing seat in the axial direction. Therefore, it is suitable for use as a fixed end bearing.
NH(NJ HJ)
NH type bearing is a combination of NJ type bearing and HJ type inclined 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, and the NH type bearing can use the width of the entire inner ring of the NJ type bearing to maintain a closer fit with the shaft. And NH type bearings in the installation and removal of more convenient.
The NH bearing 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.
double row bearing
Double row cylindrical roller bearings have cylindrical bore and conical bore (bearing rear code plus K) two structures. 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 clearance, and can simplify the structure of the positioning device, easy to install and disassemble. Commonly used double row cylindrical roller bearings have the following forms:
double row cylindrical roller bearing
NN, NNU type
The outer ring of NN type bearing has no rib, and there is a middle rib in the middle on both sides of the inner ring. Displacement in two directions in the axial direction between the shaft and the bearing seat can be allowed.
The outer ring of NNU-type bearing has ribs on both sides and a middle rib in the middle, and the inner ring has no ribs. Displacement in two directions in the axial direction between the shaft and the bearing seat can be allowed. Therefore, this type of structure is suitable for a free-running end bearing. The cage of this type of bearing is mostly made of solid cage.
NNF type
NNF type bearing is a double row full complement cylindrical roller bearing, bearing by a belt in the rib outer ring, two double rib inner ring structure type. The roller is guided by the rib of the inner ring, and the two inner rings are fixed together with a fastening ring. The structure can not only bear large radial load and axial load, but also can bear overturning moment, so it is often used as a fixed end bearing.
Type NNF bearings use contact seals on both sides. The bearing is filled with grease, and the working temperature of the grease is -50 ℃ to 110 ℃, but due to the limitation of the sealing material, the working temperature of the bearing is limited to -40 ℃ to 80 ℃. In the case of good operating conditions, the sealed NNF bearing does not need to be maintained. If the bearing is in a water vapor or polluted environment for a long time, and it is running at medium or high speed, the lubricating oil groove and lubricating oil hole on the outer ring can be used. The bearing is lubricated.
four row bearing
Four-row cylindrical roller bearings are mainly used in cold and hot rolling mills, billet machines and other rolling mills. The bearings are of a separate structure, and the bearing rings and rolling body components can be easily separated. Therefore, the bearings can be cleaned, inspected or installed. Disassembly is very convenient.
FC type
FC type bearing consists of two outer rings and an inner ring, each outer ring on both sides of the rib in the middle of the rib, the inner ring without rib.
FCD type
FCD type bearings are actually a combination of two NN type bearings.
FC type and FCD type bearings can allow the shaft relative to the bearing seat between the axial displacement in two directions. Therefore, this type of structure is suitable for a free-running end bearing. The cage of this type of bearing is mostly made of 13:58.
Accuracy Class
Cylindrical roller bearings can be divided into PO,P6,P5,P4 and P2. The accuracy level is sorted from low to high.
Method of radial clearance adjustment for cylindrical roller bearings
The commonly used methods to adjust the radial clearance of full complement cylindrical roller bearings are as follows [3]:
1. The side clearance of cylindrical and elliptical bearing bushes can be adjusted by manual scraping or by trimming after trimming and scraping on the middle surface of the bearing.
2. The top clearance of cylindrical and elliptical bearing bushes can be adjusted by manual grinding and scraping or adding pads to the middle part of the bearing when circumstances permit.
3. For multi-oil wedge fixed bearing bushes, in principle, it is not allowed to repair and adjust the bearing bush gap. If the gap is not appropriate, replace the new bush.
4. For multi-oil wedge tilting bearing, it is not allowed to repair and scrape the bearing block. When the gap is not appropriate, the bearing block should be replaced. For tiles with adjustable thickness, the amount of tiles can be adjusted by adding stainless steel pads under the adjustment block behind the tiles, or by reducing the thickness of the adjustment block. Note that for multi-oil wedge tilting bearing, the thickness error between tiles of the same group shall be less than 0.01mm.
Application
Large and medium-sized motors, locomotives, machine tool spindles, internal combustion engines, generators, gas turbines, gearboxes, rolling mills, vibrating screens, and lifting and transportation machinery.
attention problem
Vibration aspect
In normal use, the vibration of the bearing damage is very sensitive, spalling, indentation, corrosion, cracks, wear and so on will be reflected in the bearing vibration measurement. Therefore, the size of the vibration can be measured by using a special bearing vibration measuring instrument (frequency analyzer, etc.), and the specific situation of the abnormality can be inferred from the frequency distribution. The measured value is different due to the use condition of the bearing or the installation position of the sensor, so it is necessary to analyze and compare the measured value of each machine in advance to determine the judgment standard.
Temperature aspect
The use of high temperature often indicates that the cylindrical roller bearing has been in an abnormal situation. High temperatures are also detrimental to the bearing lubricant. Sometimes bearing overheating can be attributed to the bearing lubricant. If the bearing is connected for a long time at a temperature exceeding 125 ℃, the bearing life will be reduced. The causes of high temperature bearings include: insufficient lubrication or excessive lubrication, impurities in the bearing raceway, high limit speed, long-term overload operation of the bearing, etc.
Maintenance
Removal
Bearing disassembly is a regular maintenance, bearing replacement. After disassembly, if you continue to use, or need to check the state of the bearing, the disassembly should be the same as the installation carefully. Be careful not to damage the parts of the bearing, especially the disassembly of the interference fit bearing, which is difficult to operate.
It is also very important to design and make disassembly tools according to the needs. During disassembly, study the disassembly method and sequence according to the drawings, and investigate the matching conditions of the bearing, so as to ensure the safety of the disassembly operation.
Disassembly of the outer ring For the outer ring of the interference fit, several screws for the outer ring extrusion screw are set on the circumference of the shell in advance, and the screws are tightened equally on one side while disassembling. These screw holes are usually covered with blind plugs, tapered roller bearings and other separate bearings, and several cuts are set on the shell blocking shoulder. Use a cushion block to disassemble with a press, or gently tap and disassemble.
The disassembly of the inner ring can be pulled out with a press. At this point, pay attention to let the inner ring bear its pull-out force. Moreover, the pull-out clamps shown are mostly used, and no matter what kind of clamps, they must be firmly stuck on the side of the inner ring. For this reason, it is necessary to consider the size of the shaft shoulder, or study the machining of the upper groove at the shoulder to facilitate the use of the pull-out fixture.
The inner ring of large bearing is disassembled by oil pressure method. Oil pressure is applied through an oil hole provided in the bearing to make it easy to pull out. For bearings with large width, the oil pressure method is used in combination with the drawing fixture for disassembly.
The inner ring of cylindrical roller bearings can be removed by induction heating. In a short period of time to heat the local, so that the inner ring expansion after drawing the method. Induction heating is also used when a large number of such bearing inner rings need to be installed.
Cleaning
When the bearing is removed for inspection, the appearance shall be recorded by photography and other methods. In addition, confirm the amount of remaining lubricant and sample the lubricant before cleaning the bearing.
A, bearing cleaning is divided into rough washing and fine washing, and can be used in the bottom of the container on the metal grid.
B, rough washing, in the oil with a brush to remove grease or adhesion. At this time, if the bearing is rotated in oil, the rolling surface will be damaged due to foreign matter.
C, fine washing, slowly rotate the bearing in the oil, must be carefully carried out.
The cleaning agent generally used is neutral non-aqueous diesel oil or kerosene, and warm lye or the like is sometimes used as necessary. No matter what kind of cleaning agent is used, it should be filtered frequently to keep clean.
After cleaning, immediately apply anti-rust oil or anti-rust grease to the bearing.