How to prevent the influence of Timken imported bearing running sound on its service life
How to prevent the influence of Timken imported bearing running sound on its service life
2022年4月14日
Matters needing attention in analyzing load failure of outer spherical bearing
Matters needing attention in analyzing load failure of outer spherical bearing
2022年4月14日

Common problems and precautions in selecting and using Timken bearings

  • Timken bearing shows strong regularity and good repeatability in its use. When the normal high-quality bearing (bearing) is used at the beginning, the vibration and noise are relatively small, but the spectrum is scattered and the amplitude is small, which may be caused by some defects in the manufacturing process, such as surface burrs.Common problems and precautions in selecting and using Timken bearings

Common problems and precautions in selecting and using Timken bearings

  • After moving for a period of time, the vibration and noise maintain a certain level, and the spectrum is very single, with only one or two times the frequency. The frequency spectrum above three times of power frequency rarely appears, and the bearing state is very stable and enters the stable working period.Common problems and precautions in selecting and using Timken bearings
  • After continued operation and entering the later stage of use, the vibration and noise of Timken bearing began to increase, and sometimes abnormal sound appeared, but the change of vibration increase was slow. Common problems and precautions in selecting and using Timken bearings
  • At this time, the bearing kurtosis began to suddenly reach a certain value. We believe that the bearing shows initial failure at this time.Common problems and precautions in selecting and using Timken bearings
  • At this time, it is required to closely monitor the Timken bearing and pay close attention to its changes. Since 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. Common problems and precautions in selecting and using Timken bearings
  • When the vibration exceeded the vibration standard (such as ISO2372 standard), the bearing kurtosis value also began to increase rapidly. When both the vibration standard and the kurtosis value also exceeded the normal value (the relative standard of kurtosis available), we believe that the bearing has entered the late fault production, and the equipment needs to be repaired in time, Replace the bearing.Common problems and precautions in selecting and using Timken bearings
Common problems and precautions in selecting and using Timken bearings
  • The bearing shows the characteristics of late failure. The time from the occurrence of serious failure (generally bearing damage, such as shaft holding, burn, sand frame spallation, raceway, bead wear, etc.) is mostly less than one week. The larger the equipment capacity, the faster the speed, and the shorter the interval. Once the bearing fault is found in the late maintenance, it should be determined as soon as possible.
  •  For the rolling sound of the bearing, the sound detector is used to check the size and sound quality of the rolling sound of the running bearing. Even if the bearing has slight peeling and other damage, it will produce abnormal sound and irregular sound, which can be distinguished by the sound detector.
  •  Bearing vibration bearing vibration is very sensitive to the damage of Timken bearing, such as peeling, indentation, corrosion, crack, wear, etc. will be reflected in the bearing vibration measurement.Common problems and precautions in selecting and using Timken bearings
  •  Therefore, the vibration can be measured by using a special bearing vibration meter (frequency analyzer, etc.), and the specific abnormal situation can not be inferred by frequency division.Common problems and precautions in selecting and using Timken bearings
  •  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.Common problems and precautions in selecting and using Timken bearings
  • The temperature of the bearing can 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. Usually, the temperature of Timken bearing rises slowly with the start of operation and reaches a stable state after 1-2 hours.Common problems and precautions in selecting and using Timken bearings
  • The bearing capacity, rotation accuracy and wear resistance of rolling bearing will change due to its own quality and external conditions When the performance index of Timken bearing is lower than the use requirements and can not work normally, the bearing will fail or even fail. Common problems and precautions in selecting and using Timken bearings
  • Once the bearing fails and other accidents occur, the machine and equipment will stop running, loss of function and other abnormal phenomena will occur. Therefore, it is necessary to find out the causes in a short time and take corresponding measures
  • In order to maintain the proper performance and long-term use of the bearing under good conditions, the bearing must be inspected and maintained. Inspection and maintenance are very important to prevent faults. During operation, the rolling sound, vibration, temperature and lubricant of the bearing should be checked
  • One kind of rolling bearing noise is generated by Timken bearing itself, that is, the inherent noise of the bearing; The other is the noise generated after the bearing is installed, which has nothing to do with the noise of the bearing itself By listening to the sound, we can analyze some problems A) inherent noise: raceway sound “the sound of various bearings and rolling friction (cylindrical roller bearings) is the inherent sound of rolling bearings.” Common problems and precautions in selecting and using Timken bearings
  • Raceway sound is a continuous and smooth sound produced by the elastic characteristics of the rolling element when it contacts the raceway. When the bearing rotates, the rolling element rolls on the raceway; Common problems and precautions in selecting and using Timken bearings
  • Abnormal rolling friction sound can make uncomfortable abnormal metal friction sound such as “creak, creak”, which will not be made when the lubrication is good. Common problems and precautions in selecting and using Timken bearings
  • Therefore, it is not a problem in general, and attention should be paid only after the noise increases. B) noise related to bearing manufacturing: here includes cage noise and chatter. Common problems and precautions in selecting and using Timken bearings
  • Cage noise mainly occurs in ball bearing and tapered roller bearing, When the bearing rotates, it will make a sound due to the vibration of the cage and the impact between the cage and the rolling element. Common problems and precautions in selecting and using Timken bearings
  • This sound is periodic. Chatter (various bearings) is a sound with a certain frequency, which is caused by the vibration caused by large waviness on the raceway surface. C) noise caused by improper use: it exists for all kinds of bearings. 
  • When the surface of the bearing raceway or the surface of the rolling element is damaged, dented and rusted, Then there will be periodic noise and vibration Dirt noise will be generated when dust invades the bearing during operation This noise is aperiodic and also accompanied by vibration. Its sound size is not fixed, sometimes not.Common problems and precautions in selecting and using Timken bearings
  • The effect of bearing vibration on Timken bearing failure is obvious For example: peeling, indentation, corrosion, crack Wear, etc. will be reflected in the bearing vibration detection, so the vibration can be measured by using special bearing vibration measurement devices (frequency analyzer and vibration instrument, etc.) and the specific situation of abnormal vibration can be inferred through the frequency distribution. Common problems and precautions in selecting and using Timken bearings
  • The measured values vary according 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 and determine the judgment standardCommon problems and precautions in selecting and using Timken bearings
  • Generally, the temperature of Timken bearing rises slowly with the start of operation and reaches a stable state after 1 to 2 hours The normal temperature of the bearing varies with the heat capacity, heat dissipation, speed and load of the machine If the lubrication and installation are not appropriate, the bearing temperature will rise sharply and abnormal high temperature will appear. In this case, the machine must be shut down and necessary preventive measures must be taken
  • Although the bearing quality and other aspects are relatively good, the rolling bearing is a precision component, and its use must be carried out carefully accordingly. No matter how high-performance bearings are used, if they are not used properly, the expected high performance will not be obtained. The precautions for the use of bearings are as follows:Common problems and precautions in selecting and using Timken bearings

Keep the bearing and its surroundings clean.

  • Even small dust that cannot be seen by the eyes will have a bad impact on the bearing. Therefore, keep the surrounding clean so that the dust will not invade the bearing.Common problems and precautions in selecting and using Timken bearings
  • Use with care.
  • Strong impact on Timken bearing during use will produce scars and indentation, which will become the cause of the accident. In serious cases, it will crack and fracture, so we must pay attention to it.Common problems and precautions in selecting and using Timken bearings
  • Use appropriate operating tools.Common problems and precautions in selecting and using Timken bearings
  • Avoid replacing with existing tools, and appropriate tools must be used.
  • Pay attention to the corrosion of the bearing.Common problems and precautions in selecting and using Timken bearings
  • When operating Timken bearings, sweat on your hands can be the cause of rust. Pay attention to operate with clean hands and wear gloves as much as possible.
  • Because Timken bearing is a high-precision product, if it is not assembled properly, it is easy to damage the bearing channel and lead to bearing damage. The bearing shall be equipped with a special mold during assembly, which cannot be knocked at will. When pressing the shaft, only the small ring can be stressed, and when pressing the large ring, only the large ring can be stressed. Common problems and precautions in selecting and using Timken bearings
  • Pneumatic or hydraulic pressure is required during assembly. During press assembly, the upper and lower molds shall be outside the horizontal state. If there is inclination, the bearing channel will be damaged due to stress and the bearing will make a guide sound.Common problems and precautions in selecting and using Timken bearings
  • When the bearing is installed on the rotor for dynamic balance, it is easy to enter the iron filings generated during dynamic balance into the bearing, so it is necessary to perform dynamic balance before installing Timken bearing. In order to facilitate assembly, some manufacturers apply some oil or grease in the bearing chamber for lubrication effect during assembly.Common problems and precautions in selecting and using Timken bearings
  • but it is often difficult for operators to control the amount. If more oil or grease is accumulated in the bearing chamber, it is easy to enter the bearing along the shaft when the bearing rotates. The bearing shall not be coated with oil or grease. If it must be coated, it shall be controlled and there shall be no accumulation in the bearing chamber.Common problems and precautions in selecting and using Timken bearings
  • The feature of paint rust is that it often occurs in sealed motors. The sound of the motor is very good during assembly, but after it is put in the warehouse for some time, the abnormal noise of the motor becomes very large, and there is serious rust when the bearing is removed.Common problems and precautions in selecting and using Timken bearings
  •  In the past, many manufacturers thought it was the problem of Timken bearing. After our continuous publicity, now the motor factory has realized that it is mainly the problem of insulating paint. Common problems and precautions in selecting and using Timken bearings
  • This problem is mainly because the acidic substances volatilized from the insulating paint form corrosive substances at a certain temperature and humidity, which corrodes the bearing channel and leads to bearing damage. Common problems and precautions in selecting and using Timken bearings
  • At present, the problem can only be to select good insulating paint and assemble after drying and ventilation for a period of time.Common problems and precautions in selecting and using Timken bearings
  • The service life of the bearing is closely related to manufacturing, assembly and use. It must be done well in each link in order to make the bearing in the running state, so as to prolong the service life of the bearing.Common problems and precautions in selecting and using Timken bearings
  • Rolling bearings make precision parts, so it is required to be cautious when using them. Since high-performance bearings are used, if they are not used properly, they can not achieve the expected performance effect. Therefore, the following matters should be paid attention to when using Timken bearings:Common problems and precautions in selecting and using Timken bearings
  • Keep the bearings and their surroundings clean. Even if the invisible smile dust enters the bearing, it will increase the wear, vibration and noise of the bearing.
  • When using and installing, it shall be careful. It is not allowed to punch with force, directly knock the bearing with a hammer, and transfer pressure through the rolling body.Common problems and precautions in selecting and using Timken bearings
  • Use proper and accurate installation tools, try to use special tools, and try to avoid using cloth and short fiber.Common problems and precautions in selecting and using Timken bearings
  • To prevent Timken bearing from rusting, when taking the bearing directly by hand, fully wash the sweat from your hands and apply high-quality mineral oil before operation. Pay special attention to rust prevention in rainy seasons and summer.Common problems and precautions in selecting and using Timken bearings
  • How to measure the bearing clearance and how to ensure the accuracy of the clearance measurement are the problems often encountered by many users in measuring the bearing clearance. Here are some measurement methods, aspects to pay attention to and some measurement skills of Japanese NTN bearings.Common problems and precautions in selecting and using Timken bearings
  • Bearing clearance refers to the movement amount of the bearing when one side of its inner ring or outer ring is fixed when it is not installed in the shaft or bearing housing, and then the unfixed side moves radially or axially. Generally speaking, the duration of bearing rotation is long, the stop is slow, and the flexibility is good. Common problems and precautions in selecting and using Timken bearings
  • On the contrary, if the rotation time is short and the stop is sudden, the flexibility is not good. According to the moving direction, it can be divided into radial clearance and axial clearance. The measurement of the radial clearance of the whole set of bearings is not easy.Common problems and precautions in selecting and using Timken bearings
  •  The measuring force causes the elastic deformation of the ferrule and the rolling element itself and its contact. The amount of deformation is a multi factor causing the measurement error, which is related to the measuring force, the contact state and the position of the rolling element. Common problems and precautions in selecting and using Timken bearings
  • The rotation flexibility of Japanese NTN bearings is generally checked at the horizontal position. Usually fix the inner ring (or hold the inner ring by hand) and rotate the outer ring by hand to check whether there is abnormal sound and blockage during bearing rotation.Common problems and precautions in selecting and using Timken bearings
  •  Due to different structural types and sizes of bearings, there should be different requirements for their rotation flexibility. For example, single row centripetal ball bearings and single row centripetal thrust ball bearings are relatively light when rotating due to the small contact area between the rolling element and the ferrule.Common problems and precautions in selecting and using Timken bearings
  • while double row centripetal spherical bearings and thrust roller bearings are less light when checking their rotation flexibility due to the large contact area between the rolling element and the raceway and the small weight of the outer ring. For extra large bearings, there should be no jamming when rotating them, and the rotating sound is generally not checked. Common problems and precautions in selecting and using Timken bearings
  • For tapered hole bearing, the following methods can be used to supplement and check the rotation flexibility of the bearing. The specific operations are as follows: press the tapered hole bearing into the mandrel until a certain radial preload is added. Common problems and precautions in selecting and using Timken bearings
  • Under this preload, when a ferrule rotates, the rolling element should rotate. If the rolling element slides instead of rotates, it means that there are too many geometric defects of the ferrule or the size of the rolling element is uneven, and the rotation flexibility of the bearing is poor.Common problems and precautions in selecting and using Timken bearings
  • In the case of close fit between the bearing ring and the bearing seat or transmission shaft, the bearing ring may be deformed by matching with the shape of adjacent components. If deformation occurs, vibration may occur during operation. Therefore, it is important to machine the bearing pedestal and drive shaft to the required tolerances.
  • The bearing is excited by the change of the number of loaded rolling elements. When a radial load is loaded on a bearing, the number of loaded rolling elements will change slightly during operation, that is to say, it will cause the shift of load direction. In this case, it is inevitable to reduce the vibration of the roller by preloading the roller (but it is not applicable to all rolling bearings).Common problems and precautions in selecting and using Timken bearings
  • The bearing is partially damaged. A small number of bearing raceways and rolling elements may be damaged due to incorrect operation or installation. In operation, rolling damaged bearing components will produce specific vibration frequencies. Vibration frequency analysis can identify damaged Japanese NTN bearing components.Common problems and precautions in selecting and using Timken bearings