Precautions for SKF Bearing in use
Precautions for SKF Bearing in use
2022-04-24
Method of prolonging the service life of IKO imported bearings
Method of prolonging the service life of IKO imported bearings
2022-04-24

Purpose and principle of preloading NSK imported bearings

  • The temperature of IKO imported bearing can generally be inferred from the temperature outside the bearing chamber. It is more appropriate if the oil hole can be used to directly measure the temperature of the outer ring of the bearing.Purpose and principle of preloading NSK imported bearings
  • Generally, the temperature of IKO inlet bearing starts to rise slowly with the operation of the bearing, and reaches a stable state after 1-2 hours. The normal temperature of IKO imported bearing varies with the heat capacity, heat dissipation, speed and load of the machine.
  •  If the lubrication and installation parts are appropriate, the bearing temperature will rise sharply and abnormal high temperature will occur. At this time, the operation must be stopped and necessary preventive measures must be taken.Purpose and principle of preloading NSK imported bearings
  • The working temperature of IKO imported bearing can be monitored at any time by using the thermal sensor, and the automatic alarm or stop when the temperature exceeds the specified value can be realized to prevent the occurrence of combustion shaft accident.Purpose and principle of preloading NSK imported bearings
  • High temperature often indicates that IKO imported bearing is in abnormal condition. High temperature is also harmful to the lubricant of IKO imported bearings. Sometimes bearing overheating can be attributed to the lubricant of the bearing. If the bearing temperature exceeds 125 ℃ for a long time, the bearing life will be reduced. The causes of high temperature bearings include insufficient or excessive lubrication and lubricant. The oil seal contains excessive clearance, insufficient friction, etc.Purpose and principle of preloading NSK imported bearings
  • Therefore, it is necessary to continuously monitor the bearing temperature, whether it is measuring the bearing itself or other important parts. If the operating conditions remain unchanged, any temperature change can indicate that a fault has occurred.Purpose and principle of preloading NSK imported bearings
  • The bearing temperature can be measured regularly by IKO thermometer or IKO thermometer.
  • The important IKO imported bearing means that when it is damaged, it will cause the shutdown of the equipment. Therefore, this kind of bearing should be equipped with temperature detector.Purpose and principle of preloading NSK imported bearings
  • Under normal circumstances, IKO imported bearings will have a natural temperature rise after just lubrication or re lubrication and last for one or two days.Purpose and principle of preloading NSK imported bearings
  • Therefore, it is necessary to continuously monitor the bearing temperature. NTN bearing is used to measure the bearing itself or other important parts. If the operating conditions remain unchanged, any temperature change can indicate that a fault has occurred. The periodic measurement of bearing temperature can be aided by thermometer, such as digital thermometer, which can accurately measure the bearing temperature and display it in ℃ or Fahrenheit.Purpose and principle of preloading NSK imported bearings
  • Generally, the temperature of the bearing can be inferred from the temperature outside the bearing chamber. If the oil hole can be used to directly measure the temperature of the outer ring of the bearing, NTN bearing is more suitable. Usually, the temperature of the bearing starts to rise slowly with the operation of the bearing, and reaches a stable state after 1-2 hours.Purpose and principle of preloading NSK imported bearings
  •  The normal temperature of the bearing varies with the heat capacity, heat dissipation, speed and load of the machine. If the lubrication and installation parts are appropriate, the bearing temperature will rise sharply and abnormal high temperature will occu.Purpose and principle of preloading NSK imported bearings
  • r. At this time, the operation must be stopped and necessary preventive measures must be taken. NTN bearing is a precision part of imported bearings. The system realizes the optimization of workshop asset efficiency and maintenance work for the decision support of mechanical service, preventive maintenance means, condition monitoring and a series of maintenance work. Therefore, bearing plays a vital role in some industries. The shaft parts of machine tools, especially the spindle, are generally assembled with NSK Bearings or sliding bearings and rotate at a high speed, sometimes generating high heat.
  •  If this phenomenon is not eliminated in time, it will lead to overheating of the bearing and increase the temperature of the corresponding parts of the machine tool, resulting in thermal deformation. In serious cases, the height of the spindle and tailstock will be unequal, which will not only affect the accuracy and machining accuracy of the machine tool itself, but also burn out the bearing. Purpose and principle of preloading NSK imported bearings
  • The causes of main shaft bearing heating and its troubleshooting are shown in Table 1. In order to ensure the working condition of NTN bearing, it is necessary to avoid damage as much as possible. What should we do?Purpose and principle of preloading NSK imported bearings
  • Generally, if the bearing is used correctly, it can be used until the fatigue life is reached. However, there will be accidental and premature damage, which can not be resistant to use. This early damage, as opposed to fatigue life, is called the quality service limit of failure or accident. Most of them are caused by careless installation, use and lubrication, foreign matters invading from the outside, and insufficient research on the thermal effects of shafts and shells.Purpose and principle of preloading NSK imported bearings
  • As for the damage state of NTN bearing, for example, the clamping damage of the ring retaining edge of roller bearing can be considered as the reason. These reasons can also coincide with insufficient lubricant, unsuitable, defects of oil supply and drainage structure, intrusion of foreign matters, bearing installation error and excessive deflection of shaft.Purpose and principle of preloading NSK imported bearings
  • Therefore, only investigating the bearing damage, it is difficult to know the real cause of the damage. However, if you know the use machinery, service conditions, the structure around the bearing, the situation before and after the accident, and combined with the damage state of the bearing and several causes, you can prevent the recurrence of similar accidents. In order to ensure the working condition of NTN bearing, it is necessary to avoid damage as much as possible. What should we do?Purpose and principle of preloading NSK imported bearings
  • Generally, if the bearing is used correctly, it can be used until the fatigue life is reached. However, there will be accidental and premature damage, which can not be resistant to use. This early damage, as opposed to fatigue life, is called the quality service limit of failure or accident. Most of them are caused by careless installation, use and lubrication, foreign matters invading from the outside, and insufficient research on the thermal effects of shafts and shells.Purpose and principle of preloading NSK imported bearings
  • As for the damage state of NTN bearing, for example, the clamping damage of the ring retaining edge of roller bearing can be considered as the reason. These reasons can also coincide with insufficient lubricant, unsuitable, defects of oil supply and drainage structure, intrusion of foreign matters, bearing installation error and excessive deflection of shaft.Purpose and principle of preloading NSK imported bearings
  • Therefore, only investigating the bearing damage, it is difficult to know the real cause of the damage. However, if you know the use machinery, service conditions, the structure around the bearing, the situation before and after the accident, and combined with the damage state of the bearing and several causes, you can prevent the recurrence of similar accidents. The structural design, manufacturing process and material quality of ina imported bearings are analyzed.Purpose and principle of preloading NSK imported bearings
  • INA imported bearings have reasonable design and advanced nature, so that long service life of INA bearing will be longer. The manufacturing of bearings generally goes through multiple processing processes such as forging, heat treatment, turning, grinding and assembly. The rationality, advanced nature and stability of all the processing technologies will also affect the life of bearings.Purpose and principle of preloading NSK imported bearings
  •  Among them, the heat treatment and grinding processes that affect the quality of finished bearings are often more directly related to the failure of bearings. In recent years, the research on the metamorphic layer on the working surface of bearing shows that the grinding process is closely related to the surface quality of bearing.Purpose and principle of preloading NSK imported bearings
  • The metallurgical quality of ina imported bearing materials was once the main factor affecting the early failure of rolling bearings. With the progress of Metallurgical Technology (such as vacuum degassing of bearing steel), the quality of raw materials has been improved. The proportion of raw material quality factor in bearing failure analysis has decreased significantly, but it is still one of the main influencing factors of bearing failure. Proper material selection is still a factor that must be considered in bearing failure analysis.Purpose and principle of preloading NSK imported bearings
  • The main task of ina imported bearing failure analysis is to find out the main factors causing bearing failure according to a large number of background materials, analysis data and failure forms, so as to put forward targeted improvement measures, prolong the service life of the bearing and avoid sudden early failure of the bearing. For the use of bearings, noise is very common. Even the low-noise bearings in the imported Koyo bearings have the same situation. So why does it make noise? Today I will introduce its essence to you.Purpose and principle of preloading NSK imported bearings
  • The raceway sound of Koyo imported bearing and its control method raceway sound is a smooth and continuous sound generated by the rolling body rolling on the raceway surface when Koyo imported bearing is running. It is a unique basic sound that will occur in all rolling bearings. Purpose and principle of preloading NSK imported bearings
  • The general bearing sound is the sound of raceway plus other sounds. The raceway sound of ball bearing is irregular, and its frequency is above 1000Hz. Its main frequency does not change with the speed, but its total sound pressure level increases with the speed. For the bearing with loud raceway sound, the sound pressure level of raceway sound decreases with the increase of viscosity; Purpose and principle of preloading NSK imported bearingsPurpose and principle of preloading NSK imported bearings
  • For bearings with low raceway noise, the sound pressure level changes from decrease to increase when the viscosity increases to more than 20mm2 / s. The greater the rigidity of the bearing pedestal, the lower the total sound pressure level of the raceway sound. If the radial clearance is too small, the total sound pressure level and dominant frequency of raceway sound will increase sharply with the decrease of radial clearance. The methods to control the sound of raceway are: select low-noise bearings, that is, bearings with small waviness, and carefully select the service conditions. Raceway noise often affects the noise of the whole machinery. Reducing raceway noise can reduce the noise of the whole machinery.Purpose and principle of preloading NSK imported bearings
  • Impact sound of rolling element and its control method when the ball bearing or cylindrical roller bearing of larger model runs at low speed under pure radial load, due to the small centrifugal force of the rolling element, the rolling element in the non load area will impact the cage or raceway and make noise. But as the speed increases, the sound will disappear. The control methods of impact sound of rolling elements are: appropriately reduce the radial clearance, and use the bearing of cage with reasonable structure and flexible material.Purpose and principle of preloading NSK imported bearings
  • The rolling sound of imported Koyo bearings and its control method rolling sound is the harsh metal friction sound that can occur in cylindrical roller bearings on all occasions. Most of it occurs in larger types of grease lubricated bearings, which is more likely to occur in greases with degraded base oil performance and hardly occurs in oil lubrication. In addition, it is easy to occur in winter. Purpose and principle of preloading NSK imported bearings
  • When bearing pure radial load, it is easy to occur in the case of large radial clearance, and it is easy to occur in a specific speed range with different models and sizes, both continuously and intermittently. Special processing methods for the outer ring raceway can prevent the occurrence of rolling sound. Purpose and principle of preloading NSK imported bearings
  • If necessary, this kind of bearing can be selected, or the radial clearance of the bearing can be appropriately reduced, the lubricating grease with excellent performance can be used and the rigidity of the parts matched with the bearing can be improved.Purpose and principle of preloading NSK imported bearings
Purpose and principle of preloading NSK imported bearings

Purpose and principle of preloading NSK imported bearings

  • The deformation capacity is lost locally, and the grain is gradually formed and continuously expanded. Then, with the falling off of wear debris, the loaded outer layer forms a hole. Generally, when the bearing bush is pitted, the pit first appears, and then the pit gradually expands and causes the cracking of the alloy layer interface. The crack extends along the parallel direction of the interface until it peels off. Purpose and principle of preloading NSK imported bearings
  • The main reason for bearing cavitation is that the sudden change of the cross section of structural elements such as oil groove and oil hole causes strong disorder of oil flow. Bubbles are formed in the vacuum area with disorder of oil flow, and then cavitation occurs due to the collapse of bubbles due to the increase of pressure. Cavitation usually occurs in the high load area of the bearing, such as the lower bearing bush of the crankshaft main bearing.Purpose and principle of preloading NSK imported bearings
  • Due to the overload of the engine, the fatigue pitting corrosion of Koyo imported bearings refers to. Make the bearing overheat and the bearing clearance is too large, resulting in fatigue damage, fatigue pitting or fatigue falling off in the middle of the bearing. This kind of damage is mostly caused by overload, excessive bearing clearance, or unclean lubricating oil and foreign matters mixed in it. Purpose and principle of preloading NSK imported bearings
  • Therefore, when using, attention should be paid to prevent the bearing from overload and do not run at too low or too high speed; Adjust the engine to a stable state at idle speed; Ensure the normal bearing clearance and prevent the engine speed from being too high or too low; Check and adjust the working condition of the cooling system to ensure that the working temperature of the engine is appropriate.Purpose and principle of preloading NSK imported bearings
  • The chemical impurities (acid oxides, etc.) in the lubricating oil oxidize the bearing alloy to form acidic substances. The corrosion area of the bearing alloy is generally impure lubricating oil. Cause the bearing alloy to fall off locally and form irregular small cracks or pits. Improper use of bearing oil and lubricating alloy is the main reason for poor corrosion resistance of the engine.Purpose and principle of preloading NSK imported bearings
  • Local high temperature is formed, and there is a small convex metal surface in direct contact between the journal and the friction pair of Koyo bearing. In case of lack of lubrication and poor cooling, the bearing alloy will be blackened or partially burned. This fault is often caused by too tight fit between journal and bearing; Lack of lubricating oil pressure is also easy to burn the bearing. As we all know, in addition to the adverse phenomena of the bearing in use, the noise also lies in the bearing itself. Different types of NTN bearings have different noise, so how do we choose the bearing with low noise?Purpose and principle of preloading NSK imported bearings
  • Bearings with relatively low noise: when the above two types of low noise bearings cannot be used, bearings with relatively low noise can be used. The specific comparison basis is as follows:
  • The noise of ball bearing is lower than that of roller bearing, and the (friction) noise of bearing with less sliding is lower than that of bearing with more sliding; If there are many balls, the outer ring is thick and the noise is small;
  • The noise of bearings with solid cages is relatively lower than that of bearings with stamping cages;
  • The noise of bearings with plastic cages is lower than that of bearings with the above two cages;
  • The noise of bearings with high precision, especially those with higher rolling element precision, is relatively lower than that of bearings with low precision;Purpose and principle of preloading NSK imported bearingsPurpose and principle of preloading NSK imported bearings
  • The noise of small bearings is relatively lower than that of large bearings.Purpose and principle of preloading NSK imported bearings
  • Rolling bearings with low noise requirements include: among the standard bearings produced in China, some single row radial ball bearings and short cylindrical roller bearings have low noise varieties for motor bearings. The inner diameter of ball bearing φ 2.5mm to φ There are several varieties of 60mm with three suffixes of ZL, Z2 and Z3, which correspond to three different low-noise requirements respectively. Among the roller bearings, there are eight models from n309 to n322, which are also manufactured according to the low-noise standard. These bearings can be fully applicable to other machines with low noise requirements, and the price is cheap. If the type and size can meet the requirements, try to use these two types of low noise bearings.
  • There are two kinds of noise caused by problems in bearing application: scar sound and dust sound, which are described as follows:
  • Scar sound and its control method
  • If there is crack, indentation or corrosion on the rolling surface of rolling bearing, periodic vibration and noise like riveting rivets will occur. Its cycle may be fixed, but most of it has a certain corresponding relationship with the rotating speed. The scars will occur continuously on the channel, and the scars will appear on the steel ball from time to time, and this noise will change with the installation and lubrication conditions.Purpose and principle of preloading NSK imported bearings
  • The control methods of this kind of noise are as follows: do not knock the NTN bearing during installation. When the bearing is assembled with the shaft and then installed into the bearing seat, prevent the bearing from being installed obliquely; Prevent NTN bearings from rusting during storage and impact vibration during transportation; Use grease with high viscosity.Purpose and principle of preloading NSK imported bearings
  • Dust sound and its control method
  • If there are dust and other foreign matters in the rolling bearing, aperiodic vibration and so-called dust sound will occur. The magnitude of vibration and noise is uncertain, and there may or may not be.
  • The control methods of dust noise include: improving the cleaning method of NTN bearing, and strictly cleaning the NTN bearing, shaft, seat hole and matching parts before installation; Remove foreign matters in the lubricant; Improve the sealing of NTN bearing; Avoid using plastic cages with impure materials or embedded foreign matters.Purpose and principle of preloading NSK imported bearings
  • Noise caused by lubrication factors and Its Countermeasures
  • Incorrect lubricant selection, insufficient lubricant or aging hardening can lead to vibration and noise of NTN bearing, and this noise has no certain law. In this case, only select the appropriate lubricant, adjust the amount of lubricant, prolong the service life of lubricant and reasonably determine the replacement cycle.
  • Noise related to main engine and Its Countermeasures
  • This kind of noise is not caused by NTN bearings alone, so it is futile to find the reason only from the bearing. We should pay full attention to the main engine and improve the performance of the main engine if necessary. This paper mainly describes the common buzzer sound and frame resonance sound in the motor.Purpose and principle of preloading NSK imported bearings
  • Buzzer of motor and Its Countermeasures
  • The axial vibration of the motor shaft will cause great high-frequency noise – buzzer, and its frequency is the same as the axial vibration frequency, which can be constant or variable. The method to prevent the buzzer is the same as that to prevent the axial vibration.Purpose and principle of preloading NSK imported bearings
  • Resonance sound of NTN bearing frame and Its Countermeasures
  • When the axial natural vibration of NTN inlet bearing frame is caused by the axial natural vibration of the above-mentioned outer ring mass, a noise called resonant sound will be generated. The method of pre tightening can improve the axial natural frequency of the outer ring mass system, destroy the resonance condition and reduce the noise. Proper material selection is still a factor that must be considered in bearing failure analysis. Purpose and principle of preloading NSK imported bearings
  • The main task of NSK bearing failure analysis is to find out the main factors causing bearing failure according to a large number of background materials, analysis data and failure forms, so as to put forward targeted improvement measures, prolong the service life of the bearing and avoid sudden early failure of the bearing. The installation condition is one of the primary factors in the use factors. Purpose and principle of preloading NSK imported bearings
  • The improper installation of the bearing often leads to the change of the stress state between the parts of the whole bearing, and the NSK bearing operates in an abnormal state and fails early. According to the technical requirements of bearing installation, use, maintenance and repair, monitor and inspect the load, speed, working temperature, vibration, noise and lubrication conditions borne by the running bearing, find out the cause immediately and adjust it to make it return to normal.Purpose and principle of preloading NSK imported bearings
  • First of all, the reasonable design and advanced nature of the structure will lead to longer bearing life. The manufacturing of bearings generally goes through multiple processing processes such as forging, heat treatment, turning, grinding and assembly. The rationality, advanced nature and stability of all the processing technologies will also affect the life of bearings.Purpose and principle of preloading NSK imported bearings
  •  Among them, the heat treatment and grinding processes that affect the quality of finished bearings are often more directly related to the failure of bearings. In recent years, the research on the metamorphic layer of the working surface of NSK bearing shows that the grinding process is closely related to the surface quality of the bearing.
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