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Fault causes and solutions of bearing inner race, outer race and bearing race

What is the bearing inner sleeve?

  • The bearing running inner sleeve can also be called the bearing running inner ring, which usually means that there is a gap between the inner circle of the bearing and the shaft, resulting in asynchronous rotation with the shaft.
  • What is a bearing running jacket?Fault causes and solutions of bearing inner race, outer race and bearing race
  • The bearing outer race can also be called the bearing outer race, which usually means that the clearance between the outer circle of the bearing and the bearing chamber is too large, resulting in the outer race slipping in the bearing chamber and rotating with the shaft.Fault causes and solutions of bearing inner race, outer race and bearing race

Fault causes and solutions of bearing inner race, outer race and bearing race

  • 1. The bearing ball or retainer is damaged, so that the inner and outer rings are stuck into a body. Under the torque of the shaft, the inner ring or outer ring is forced to rotate.
  • 2. The interference between the bearing and the shaft is insufficient, resulting in insufficient friction between the bearing and the journal and running away from the inner ring.
  • 3. The poor positioning of the shaft leads to the large movement of the shaft in the axial direction, causing the bearing to run away from the inner ring.
  • 4. The axial fixation of the bearing is unreasonable, or the internal ink and shoulder of the bearing are unstable.
  • 5. If the bearing is unqualified, inferior materials shall be used.Fault causes and solutions of bearing inner race, outer race and bearing race
  • 6. Insufficient lubrication leads to poor bearing rotation and inner race running.Fault causes and solutions of bearing inner race, outer race and bearing race
  • Reasons for bearing running out of outer ring:Fault causes and solutions of bearing inner race, outer race and bearing race
  • The fit between INA Bearing and shaft (hole) has strict requirements on the machining accuracy, fit tolerance, installation and assembly accuracy, material, use and maintenance of shaft, hole and bearing. Any bad aspect may cause the bearing to run.Fault causes and solutions of bearing inner race, outer race and bearing race
  • 1. Fit tolerance: there are strict standards for the fit tolerance between bearing and shaft (hole). Different specifications, accuracy, stress conditions and service environment have different requirements for fit tolerance. The friction between the rolling element and the inner sleeve of the bearing is rolling friction. The friction coefficient of the two contact surfaces is very small, and the friction force is very small. The fit between bearing and shaft (hole) is very tight, which is generally interference fit and transition fit in a few cases. If the fit tolerance between the bearing and the shaft and hole is too large, it is clearance fit, and the extrusion force becomes smaller. Under the action of torque, the shaft (bearing) will destroy the rest between them and produce sliding, resulting in what the editors call “race phenomenon”.Fault causes and solutions of bearing inner race, outer race and bearing race
  • 2. Machining accuracy and installation accuracy: refer to the machining error, surface roughness, installation and assembly accuracy and other technical parameters of shaft, bearing and bearing seat hole. These have industry standards. Once it fails to meet the standard, it will affect the fit tolerance and cause bearing race. For another example, if the coaxiality of the installation is not enough, the bearing will vibrate greatly, cause shaft bending, increase the load, cause bearing failure, increase the number of bearing replacement, affect the dimensional tolerance between the bearing and the shaft or hole, and then destroy the matching tolerance between the bearing and the shaft (hole). All these may cause bearing race and bearing failure.Fault causes and solutions of bearing inner race, outer race and bearing race
  • 3. The material of shaft and NSK bearing is also very critical. Different types of bearings should be made of appropriate bearing steel, with high strength and stiffness, good wear resistance and small friction coefficient of bearing alloy, so as to ensure the normal use of bearings and reduce the possibility of race.Fault causes and solutions of bearing inner race, outer race and bearing race

Poor routine maintenance:Fault causes and solutions of bearing inner race, outer race and bearing race

  • (1) The coupling and its vulnerable parts are seriously worn, and the installation degree will be damaged if the coaxiality and concentricity are out of tolerance.
  • (2) The locking parts of the bearing, such as lock nut, snap ring and end cover, are not locked in place, which destroys the matching accuracy of the bearing.
  • (3) Poor lubrication, increased ball wear, increased temperature, uneven thermal expansion of bearings and mating parts, and damage the mating accuracy.
  • (4) The disassembly and assembly of the bearing is not standardized, which damages the shaft or bearing and destroys the fitting accuracy.
  • Hazards of bearing race:
  • 1. The negative impact on the equipment is very large. It intensifies the wear of mating parts, and even charges seriously, which damages the equipment and reduces the accuracy of the machine;
  • 2. Because the friction force is increased, a large amount of energy is transformed into useless heat energy and noise, and the operation efficiency is reduced. If this happens, stop the operation and arrange maintenance as soon as possible according to the actual situation.
  • Common solutions for bearing inner race:
  • For the inner race of shaft running, pitting method is adopted in case of emergency, but it is only emergency; If conditions permit, there are repair welding machine processing, shaft sleeve brush plating, spraying, micro arc welding, laser welding, etc. the following civilization makes a simple analysis on the advantages and disadvantages of several repair technologies for your reference.
  • 1. Pitting process
  • Pitting repair process is an emergency measure. After repair, the coordination between bearing inner ring and shaft is only point contact. Therefore, under heavy load operation, pitting is very easy to produce fatigue wear and repair failure.
  • 2. Brush plating process
  • Its advantage is that it can realize online repair, and its disadvantage is very obvious. In brush plating process, the brush plating coating is limited by the amount of wear. Generally, the brush plating thickness of brush plating coating is less than 0.2mm. When the wear is greater than 0.2mm, the brush plating efficiency will be doubled, and when the brush coating is too thick, the brush coating is easy to fall off during use and the service life is short.Fault causes and solutions of bearing inner race, outer race and bearing race
  • 3. Thermal spraying repair technology
  • Thermal spraying refers to a series of processes in which fine and dispersed metallic or non-metallic coating materials are deposited on a prepared substrate surface in a molten or semi molten state to form a spraying deposition layer. It is a technology that uses a certain heat source (such as arc, plasma spraying or combustion flame) to heat powdered or filamentous metal or non-metallic materials to the molten or semi molten state, and then spray them to the pretreated substrate surface at a certain speed with the help of flame retention itself or compressed air to deposit and form a surface coating with various functions. Use the energy provided by fuel gas or electric arc.Fault causes and solutions of bearing inner race, outer race and bearing race
  • The major limitation of thermal spraying process is that it can not be repaired on site, and it still needs machining after spraying, which has low efficiency. It has great limitations for the application of large shaft head wear.Fault causes and solutions of bearing inner race, outer race and bearing race
  • 4. Processing technology of repair welding machine
  • Repair welding machine processing repair process is a common way in the traditional repair process, which is characterized by high repair accuracy. Its disadvantage is that the thermal stress causes great damage to the material, and it is easy to break the shaft during operation, resulting in shutdown or shutdown accidents.
  • 5. Soray carbon nano polymer repair technology
  • Soray carbon nano polymer material repair technology belongs to a “cold repair” technology, which can implement off-line machining repair or on-site on-line repair, with flexible application. This technology has no strict requirements on the wear form and defect degree of the shaft head. As long as the basic mechanical strength of the shaft head meets the use, it can be repaired by this technology.
  • Soray carbon nano polymer repair technology is divided into on-line repair and off-line repair. Among them, on-line repair is tooling repair, scraping repair and component positioning repair; Offline repair is machining repair. Soray carbon nano polymer materials have excellent turning, milling, planing and grinding characteristics.
Fault causes and solutions of bearing inner race, outer race and bearing race

Common solutions for bearing outer race:

  • 1. Emergency repair
  • 1.1. Pitting or knurling of bearing chamber. Pitting the bearing chamber is to remove the electric shed, remove the lower end cover, evenly arrange and flush the small pits on the circumferential surface of the end cover bearing chamber and the bearing with a sharpened steel punch, and turn up burrs around each small pit to increase the surface roughness of the bearing chamber, so as to reduce the hole diameter. After cleaning the dust and other sundries, reinstall it. After such treatment, after running for a period of time or disassembling for several times, the peak value of small pit or knurled bulge will soon be reduced by grinding, the roughness of bearing chamber will be reduced, the aperture will soon return to the original size, and the bearing jacket may rotate again. This repair method can only be used for short-term emergency maintenance.Fault causes and solutions of bearing inner race, outer race and bearing race
  • 1.2 treatment of corrugated gasket. For general small motors with center height of h160 and below, the bearing structure is relatively simple, and there is even no bearing inner cover or outer cover. The axial pad between the bearing and the end cover is provided with corrugated spring gasket to adjust the axial clearance to reduce the bearing noise and vibration, as shown in Figure 1.Fault causes and solutions of bearing inner race, outer race and bearing race
  • If the bearing sleeve rotates, a corrugated gasket or iron flat gasket can be added to increase the axial pressure to alleviate the rotation of the bearing sleeve. It can also be padded with oil resistant and heat-resistant asbestos rubber pad (which can be cut with national standard gb539 oil resistant asbestos rubber plate), so as to increase the friction between the bearing and the outer cover or corrugated gasket and slow down the rotation of the outer sleeve. This treatment is to add a pad on one side of the bearing, which will increase the axial pressure of the bearing of the original structure, which is easy to increase the noise and vibration and accelerate the damage of the bearing. Therefore, this kind of pad should be appropriate, and this treatment can only be used for short-term emergency repair.Fault causes and solutions of bearing inner race, outer race and bearing race
  • 1.3. Jam the bearing sleeve. If a ball bearing and a column bearing are used at both ends of the motor respectively, if the bearing jacket rotates, a pad can be added on both ends of the bearing jacket to clamp the bearing jacket to prevent the jacket from rotating in the bearing chamber (as shown in Figure 2). For flameproof motors, if the flameproof surface is set on the plane of the inner cover, this treatment will increase the original flameproof gap due to the addition of hard gaskets. Note that the plane flameproof gap between the inner cover and the end cover shall be controlled to be less than or equal to 0.2mm (class IIB factory flameproof motor). For class I mining flameproof motor, the gap shall be less than or equal to 0.5mm.Fault causes and solutions of bearing inner race, outer race and bearing race