Six precautions for selecting NTN imported bearing
Precautions for select NTN imported bearing
2022年4月16日
Failure analysis of NSK tapered roller bearing
Failure analysis of NSK tapered roller bearing
2022年4月16日

Importance of Timken bearing inspection

  • The state of ina imported bearings is directly related to the operation state of rotating equipment. Bearings are widely used in equipment. Therefore, it is important to do a good job in the condition monitoring and maintenance of large-scale rotating equipment, especially in the practical application of large-scale production equipment. Through temporary practice and exploration, some practical skills of bearing actual fault diagnosis have been accumulated.Importance of Timken bearing inspection
  • Vibration analysis is a practical method for condition monitoring and fault diagnosis of ina imported bearings. Attention must be paid to the accuracy and authenticity of the collected signals. In practice, attention should be paid to the selection of the location of measuring points and acquisition methods. To truly and accurately reflect the bearing vibration state.Importance of Timken bearing inspection
  •  Therefore, it is necessary to arrange measuring points near the bearing. The free end of the motor is generally provided with a rear fan cover, and the measuring points are selected in the fixing screws of the fan cover, which has a good monitoring effect. In addition, it is necessary to collect and analyze the vibration signals for many times and compare them comprehensively. Ability to draw accurate conclusions.Importance of Timken bearing inspection
  • Ina imported bearing shows a strong regularity in its use, which is found in the temporary production condition monitoring. And the repeatability is very good. When the normal high-quality bearing is put into use, the vibration and noise are relatively small, but the spectrum is somewhat scattered and the amplitude is small, which may be caused by some defects in the manufacturing process, such as surface burrs.Importance of Timken bearing inspection
  • Vibration and noise maintain a certain level after exercise for a period of time. The spectrum is very single, with only one or two frequency doubling. The frequency spectrum above three times of power frequency rarely appears, and the bearing state is very stable and enters the stable working period.Importance of Timken bearing inspection
  • The vibration and noise of the bearing began to increase and entered the later stage of use after continued operation. Sometimes there is abnormal sound, but the vibration increases slowly. At this time, the kurtosis value of the bearing suddenly reaches a certain value. It is considered that the bearing at this time is an initial fault.Importance of Timken bearing inspection
  • It is required to closely monitor the bearing. Pay close attention to its changes. Then, the bearing kurtosis value began to decline rapidly and close to the normal value, while the vibration and noise began to increase significantly, and the increase amplitude began to accelerate. When the vibration exceeded the vibration specification (such as ISO2372 specification), the bearing kurtosis value also began to increase rapidly. When the vibration specification was exceeded and the kurtosis value also exceeded the normal value (kurtosis relative standard available), it was considered that the imported bearing of ina had entered the late fault production, and the equipment needed to be repaired in time, Replace the bearing.
  • The larger the equipment capacity, the bearing shows the characteristics of late failure, and the time from the occurrence of serious failure (generally bearing damage, such as shaft holding, burn, sand frame crack, raceway, bead wear, etc.) is usually less than one week. The faster the speed, the shorter the interval. Therefore, in the actual bearing fault diagnosis, once the late fault characteristics are found, the bearing fault should be determined and the maintenance should be arranged as soon as possible.Importance of Timken bearing inspection
  • The assembly quality index of ina imported bearings, that is, the assembly accuracy requirements are mainly radial clearance and width. There is a certain functional relationship between axial clearance and radial clearance. Therefore, the axial clearance can be indirectly controlled by controlling the radial clearance.
  • For deep groove ball bearings, cylindrical roller bearings, self-aligning ball bearings and self-aligning roller bearings, the radial clearance is mainly controlled.Importance of Timken bearing inspection
  • For thrust ball bearing, thrust roller bearing and tapered roller bearing, the height and width are mainly controlled.
  • For angular contact ball bearings, the contact angle is mainly controlled.Importance of Timken bearing inspection
  • The basic requirements of rolling bearing assembly are: on the premise of ensuring the assembly quality index, the sleeve rate should be high, which should generally be more than 95%. Obvious loose defects are not allowed on the finished ina bearing ring. It will reduce the density of ferrule and enrich more micropores, low melting point impurities, gases and non-metallic inclusions Like the ribbon carbide, it plays the role of dividing the continuity of the matrix, causing component segregation and matrix embrittlement, which greatly reduces the comprehensive mechanical properties of the ferrule.
  • The black-and-white concentration difference of martensite matrix in quenching and tempering state, high macro hardness value and loose defects are also potential factors that can not be ignored to induce grinding cracks. The appearance of black-and-white concentration difference indicates that there are serious banded carbides in the original structure, resulting in the segregation of carbon lattice concentration on and between bands. Therefore, after quenching, the overheating tendency between bands and the difference of MS point are increased.Importance of Timken bearing inspection
  • The influence of grinding quality on the premature failure of ina bearing can be judged from the above test results. The grinding crack and grinding burn on one side of the raceway are a direct cause of the collapse of the ferrule and the premature failure of the bearing. The macro morphology of the crack and the distribution characteristics of grinding burn revealed in this example show that the original position of the raceway is too deviated or the R of the raceway is not round, which increases the grinding allowance on one side of the raceway. When the feed rate is large in the coarse grinding stage When the grinding speed is fast, the whole raceway produces uneven grinding.Importance of Timken bearing inspection
  •  If the grinding wheel is not trimmed in time, it will promote the embedding or adhesion of grinding debris, resulting in the blockage and passivation of the grinding wheel pores, which will increase the imbalance of the grinding wheel, aggravate the spindle vibration, and even the grinding chatter caused by the vibration of the machine tool. Obviously, the grinding force changes periodically, forming intermittent burn strips.
  • In order to further understand the hardness distribution of ferrule and the microstructure characteristics of quenching and tempering microstructure and surface layer, the partially cracked inner ring and its fragments are selected, the macro hardness is set on the end face, and the longitudinal metallographic samples are intercepted near the crack by wire cutting method.Importance of Timken bearing inspection
  • In the working process of INA Bearing, due to the influence of external or internal factors, the original matching clearance is changed, the accuracy is reduced, and even “bite” is called clearance change failure. External factors such as excessive interference, improper installation, expansion caused by temperature rise, instantaneous overload, etc., and internal factors such as residual austenite and residual stress in an unstable state are the main reasons for the change and failure of clearance.Importance of Timken bearing inspection
  • If the bearing is well lubricated and properly blocks sundries and moisture, it means that the oil seal should not be worn However, when opening the bearing housing, check the bearing and regularly check the oil seal Check the condition of oil seals near the bearing to ensure that they are sufficient to prevent hot liquid or corrosive liquid or gas from penetrating into the bearing along the axis. If the oil seal is worn, replace it as soon as possible
  • High temperature often indicates that ina bearing is in abnormal condition High temperatures are also harmful to lubricants in bearings Sometimes bearing overheating can be attributed to the lubricant of the bearing If the bearing operates for a long time at a temperature of more than 125 ℃, the service life of the bearing will be reduced
  • The causes of high-temperature bearing include insufficient or excessive lubrication, magazine contained in lubricant, excessive load, bearing damage, insufficient clearance, high-temperature friction caused by oil seal, etc
  • Check the condition of the running machine and monitor it to avoid equipment shutdown Human sweat is a colorless, transparent or light yellow liquid with salty taste and weak acid. Its pH value is 5 ~ 6. In addition to sodium, potassium, calcium and magnesium salts, it also contains a small amount of organic acids such as urea, lactic acid and citric acid. When sweat comes into contact with metal, a layer of sweat film will be formed on the metal surface, which will cause electrochemical effect on metal and corrode metal
  • Under some special service conditions, adding a small amount of solid lubricant to the grease, such as adding 3 ~ 5% molybdenum disulfide 1, can reduce wear and improve the compression and heat resistance. For special conditions such as high temperature, elegance, high vacuum, corrosion resistance, radiation resistance and extremely low temperature, adding solid lubricant to engineering plastics or powder metallurgy materials can make Koyo bearing parts with self-lubricating performance. For example, bonding solid lubricant to raceway A lubricating film is formed on the cage and the rolling element, which has a certain effect on reducing friction and wear
  • Viscosity is an important characteristic of lubricating oil. The viscosity directly affects the fluidity of lubricating oil and the thickness of oil film formed between friction surfaces. The viscosity of lubricating oil under the working temperature of Koyo bearing is generally 12-15cst. The higher the speed of bearing, the lower the viscosity should be selected, and the heavier the load, the higher the viscosity should be selected. The commonly used lubricating oils include mechanical oil, high-speed mechanical oil, steam turbine oil, compressor oil, transformer oil, cylinder oil, etc
  • Oil dripping lubrication is suitable for bearing components requiring quantitative supply of lubricating oil. The amount of oil dripping is generally one drop every 3-8 seconds. Excessive amount of oil will increase the bearing temperature
  • The filtered oil is delivered to the Koyo bearing parts by the oil pump. The lubricating oil after the bearing is filtered and cooled before use. Since the circulating oil can take away some heat and cool the bearing, this method is applicable to the bearing parts with high speed
  • The dry compressed air is mixed with the lubricating oil through the spray to form an oil mist. The jet bearings can effectively cool the bearing and prevent impurities from entering. This method is suitable for lubrication of high-speed and high temperature bearing parts.
  • Use the oil pump to shoot the high-pressure oil into the bearing through the nozzle, and the oil injected into the bearing flows into the oil groove through the other end of the bearing. When the bearing rotates at high speed, the rolling element and cage also form air flow around at a fairly high rotation speed. It is difficult to send the lubricating oil to the bearing by general lubrication method. At this time, the lubricating oil must be sprayed into the bearing by high-pressure injection method, and the position of the nozzle should be placed between the inner ring and the center of the cage
  • The installation of the bearing shall be determined according to the bearing structure, size and the matching nature of Koyo bearing components. The pressure shall be directly added to the end face of the tightly matched ferrule, and the pressure shall not be transmitted through the rolling element. The installation of the bearing is general
  • In general, Timken imported bearings of Zhengchang brand have their own special designers to design the external packaging, and arrange factories with qualified production conditions for production. Therefore, the packaging is very clear and unambiguous from lines to color blocks. There are unique designs specially designed to protect their own intellectual property rights on the accessories packaging of some brands.
  • Brand words and labels will be printed on the bearing body. The font is very small, but most of the products produced by the original factory use steel printing technology, and they are pressed before overheating treatment. Therefore, although the font is small, it is deeply concave and very clear. The font of counterfeit products is not only fuzzy, but also floating on the surface due to the rough printing technology. Some of them can even be easily erased by hand.Importance of Timken bearing inspection
  • Hold the bearing body sleeve of the bearing with your left hand and rotate the sleeve with your right hand to listen for any noise. Due to the backward production conditions of most counterfeit products and the complete manual workshop operation, impurities such as sand will inevitably be mixed in the production process and hidden in the Timken imported bearing, so it will make a noise when rotating. This is a big difference from the factory brand that strictly implements production standards and operates with machines.Importance of Timken bearing inspection
  • This should be paid special attention when purchasing bearings. Since the current domestic antirust technology is not particularly good, it is easy to leave thick oil traces when antirust the bearing body, and it is sticky when holding it in your hand. However, there is almost no trace of antirust oil on the foreign original bearing. However, a particularly careful expert said that the bearing smells like a smell. It must be under antirust oil, but it can’t be seen.Importance of Timken bearing inspection
  • The so-called chamfer of Timken imported bearing is the junction of horizontal and vertical surfaces. Due to the limitation of production technology, the fake bearing is not handled satisfactorily in these corners.Importance of Timken bearing inspection
  • Vibration is very sensitive to bearing damage. Peeling, indentation, corrosion, crack and wear will be reflected in bearing vibration measurement. Therefore, the magnitude of vibration can be measured by using a special bearing vibration meter (frequency analyzer, etc.), and the specific situation of abnormality can not be inferred through frequency division. Importance of Timken bearing inspection
  • The measured values are different due to the service conditions of the bearing or the installation position of the sensor. Therefore, it is necessary to analyze and compare the measured values of each machine in advance to determine the judgment standard.Importance of Timken bearing inspection
  • Next, let’s look at the effect of temperature on the bearing.Importance of Timken bearing inspection
  • High temperature often indicates that the bearing is in an abnormal condition. High temperature is also harmful to the lubricant of Timken imported bearings. Sometimes bearing overheating can be attributed to the lubricant of the bearing. If the temperature of the bearing exceeds 125 ℃ for a long time, the service life of the bearing will be reduced. The causes of high temperature bearings include insufficient or excessive lubrication and lubricant. It contains impurities, excessive load, bearing ring damage, insufficient clearance, high friction caused by oil seal, etc.Importance of Timken bearing inspection
Importance of Timken bearing inspection

Importance of Timken bearing inspection

  • 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.Importance of Timken bearing inspection
  • 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. Important bearing means that when it is damaged, it will cause equipment shutdown. Therefore, this kind of Timken imported bearing should be equipped with temperature detector. Importance of Timken bearing inspection
  • In general, Timken imported bearings of Zhengchang brand have their own special designers to design the external packaging, and arrange factories with qualified production conditions for production. Therefore, the packaging is very clear and unambiguous from lines to color blocks. There are unique designs specially designed to protect their own intellectual property rights on the accessories packaging of some brands.Importance of Timken bearing inspection
  • Brand words and labels will be printed on the bearing body. The font is very small, but most of the products produced by the original factory use steel printing technology, and they are pressed before overheating treatment. Importance of Timken bearing inspection
  • Therefore, although the font is small, it is deeply concave and very clear. The font of counterfeit products is not only fuzzy, but also floating on the surface due to the rough printing technology. Some of them can even be easily erased by hand.Importance of Timken bearing inspection
  • Hold the bearing body sleeve of the bearing with your left hand and rotate the sleeve with your right hand to listen for any noise. Due to the backward production conditions of most counterfeit products and the complete manual workshop operation, impurities such as sand will inevitably be mixed in the production process and hidden in the Timken imported bearing, so it will make a noise when rotating. This is a big difference from the factory brand that strictly implements production standards and operates with machines.Importance of Timken bearing inspection
  • This should be paid special attention when purchasing bearings. Since the current domestic antirust technology is not particularly good, it is easy to leave thick oil traces when antirust the bearing body, and it is sticky when holding it in your hand. However, there is almost no trace of antirust oil on the foreign original bearing. However, a particularly careful expert said that the bearing smells like a smell. It must be under antirust oil, but it can’t be seen.Importance of Timken bearing inspection.Importance of Timken bearing inspection
  • The so-called chamfer of Timken imported bearing is the junction of horizontal and vertical surfaces. Due to the limitation of production technology, the fake bearing is not handled satisfactorily in these corners.Importance of Timken bearing inspection
  • Vibration is very sensitive to bearing damage. Peeling, indentation, corrosion, crack and wear will be reflected in bearing vibration measurement. Therefore, the magnitude of vibration can be measured by using a special bearing vibration meter (frequency analyzer, etc.), and the specific situation of abnormality can not be inferred through frequency division.Importance of Timken bearing inspection
  •  The measured values are different due to the service conditions of the bearing or the installation position of the sensor. Therefore, it is necessary to analyze and compare the measured values of each machine in advance to determine the judgment standard.Importance of Timken bearing inspection
  • Next, let’s look at the effect of temperature on the bearing.Importance of Timken bearing inspection
  • High temperature often indicates that the bearing is in an abnormal condition. High temperature is also harmful to the lubricant of Timken imported bearings. Sometimes bearing overheating can be attributed to the lubricant of the bearing. If the temperature of the bearing exceeds 125 ℃ for a long time, the service life of the bearing will be reduced. The causes of high temperature bearings include insufficient or excessive lubrication and lubricant. It contains impurities, excessive load, bearing ring damage, insufficient clearance, high friction caused by oil seal,Importance of Timken bearing inspection etc.Importance of Timken bearing inspection
  • 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.Importance of Timken bearing inspection
  • 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. Important bearing means that when it is damaged, it will cause equipment shutdown. Therefore, this kind of Timken imported bearing should be equipped with temperature detector. Timken imported bearing I rotation, inner ring
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