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. Precautions to avoid Timken bearing failure
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.Precautions to avoid Timken bearing failure
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.Precautions to avoid Timken bearing failure
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 Inherent noise: raceway sound “the sound of various bearings and rolling friction (cylindrical roller bearings) is the inherent sound of rolling 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; Precautions to avoid Timken bearing failure
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. Therefore, it is not a problem in general, and attention should be paid only after the noise increases. Noise related to bearing manufacturing: Precautions to avoid Timken bearing failure
here includes cage noise and chatter. Cage noise mainly occurs in ball bearings and tapered roller bearings, 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. This sound is periodic. Precautions to avoid Timken bearing failure
Chatter (various bearings) is a sound with a certain frequency, which is generated by the vibration caused by large waviness on the raceway surface. Noise caused by improper use: it exists for all kinds of bearings. Precautions to avoid Timken bearing failure
When the surface of the bearing raceway or 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.Precautions to avoid Timken bearing failure
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. Precautions to avoid Timken bearing failure
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 standard.Precautions to avoid Timken bearing failure
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.Precautions to avoid Timken bearing failure
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.Precautions to avoid Timken bearing failure
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. Precautions to avoid Timken bearing failure
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:Precautions to avoid Timken bearing failure
Keep the bearing and its surroundings clean.Precautions to avoid Timken bearing failure
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.Precautions to avoid Timken bearing failure
Use with care.Precautions to avoid Timken bearing failure
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.
Use appropriate operating tools.Precautions to avoid Timken bearing failure
Avoid replacing with existing tools, and appropriate tools must be used.
Pay attention to the corrosion of the bearing.
When operating Timken bearings, sweat on your hands can be the cause of rust. Pay attention to operate with clean hands and try to wear gloves.Precautions to avoid Timken bearing failure
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. Precautions to avoid Timken bearing failure
When pressing the shaft, only the small ring can be stressed, and when pressing the large ring, only the large ring can be stressed. 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.Precautions to avoid Timken bearing failure
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, but it is often difficult for operators to control the amount.Precautions to avoid Timken bearing failure
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.Precautions to avoid Timken bearing failure
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.Precautions to avoid Timken bearing failure
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. Precautions to avoid Timken bearing failure
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. At present, the problem can only be to select good insulating paint and assemble after drying and ventilation for a period of time.Precautions to avoid Timken bearing failure
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.Precautions to avoid Timken bearing failure
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:Precautions to avoid Timken bearing failure
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.Precautions to avoid Timken bearing failure
Use proper and accurate installation tools, try to use special tools, and try to avoid using cloth and short fiber.Precautions to avoid Timken bearing failure
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.
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.Precautions to avoid Timken bearing failure
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. 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. 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. 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.
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. Precautions to avoid Timken bearing failure
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. Precautions to avoid Timken bearing failure
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. 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.Precautions to avoid Timken bearing failure
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.Precautions to avoid Timken bearing failure
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).Precautions to avoid Timken bearing failure
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.Precautions to avoid Timken bearing failure
As we all know, NTN imported bearings are precision parts and require considerable caution in use, that is, high-performance bearings are used. If they are not used properly, they can not achieve the expected performance effect, and it is easy to damage NTN imported bearings.Precautions to avoid Timken bearing failure
Most bearings are broken for many reasons – exceeding the original estimated load, ineffective sealing, too small NTN inlet bearing clearance caused by too tight fit, etc. Any of these factors has its special damage type and will leave special damage traces.Precautions to avoid Timken bearing failure
Therefore, by examining the damaged bearing, we can find the possible causes in most cases. Generally speaking, one third of the NTN imported bearing damage is due to fatigue damage, the other one third is due to poor lubrication, and the other one third is due to pollutants entering the bearing or improper installation and treatment.
How to protect it and prolong its service life, the following matters should be paid attention to when using the bearing:Precautions to avoid Timken bearing failure
The installation and adjustment of low-noise NTN bearing can also follow the grouping method of long-life bearing, so that the matching interference is more consistent, and the clearance of NTN bearing is also more consistent. It is hoped that the matching interference will take a smaller value within the possible range, so as to ensure that the deformation of NTN bearing raceway is small, and the noise caused by the passage of rolling element will be reduced.Precautions to avoid Timken bearing failure
The clearance has a great influence on the noise. The ideal state is that when the NTN bearing is in the high temperature state of operation, the clearance value is just zero. The methods to judge the excessive clearance are: the axial displacement of the bearing in the static state, the reciprocating amplitude is large, and a large and turbid noise is emitted during operation.Precautions to avoid Timken bearing failure
If there is an annoying shriek during operation, it indicates that the preload of NTN bearing is too large and the bearing has too large pre interference. The preload should be slightly relaxed. If the clearance is too large, the two bearing rings can be slightly offset along the axial direction: it not only reduces the clearance, but also increases the axial rigidity and reduces the bearing noise.
When the rolling element enters the no-load area, it will slip or move left and right, which will not only increase the noise, but also cause wear. Small clearance and large axial stiffness can eliminate this phenomenon. However, the clearance should not be too small, so as not to cause excessive temperature and shorten service life.
Sometimes, due to the large working temperature range of the main engine or the large dispersion of the size between the shaft and the bearing seat hole, it is impossible to obtain a more appropriate clearance at one time. In this case, the elastic constant pressure preloading method can be adopted for the outer ring of NTN bearing.