FAG bearing use temperature and bearing internal clearance
FAG bearing use temperature and bearing internal clearance:
When the conduction heat of the shaft is high or the hollow hole of the shaft passes through the high-temperature steam, the temperature difference between the inner ring and the outer ring of the bearing becomes large, the internal clearance of the bearing is reduced, and there is a risk of early damage of the bearing. The amount of reduction in the internal clearance of the bearing can be calculated from the temperature difference between the inner ring and the outer ring of the bearing. When working under the above conditions, it is necessary to calculate the reduction of the internal clearance of the bearing and correctly select the internal clearance of the bearing.
Introduction to the structure of cylindrical roller bearings
Single row cylindrical roller bearings:
Single row cylindrical roller bearings are separable bearings for easy installation and disassembly. Both ferrules can be tightly fitted, and the contact line between the modified roller and raceway reduces stress concentration.
Double row cylindrical roller bearings:
Double row cylindrical roller bearings are floating bearings, and their separability makes installation and disassembly convenient. A tight fit can be used for both ferrules.
Double row cylindrical roller bearings have almost no inclination angle.
The structural form of the cylindrical roller bearing:
Types N, NU, NN and NNU are available for free-side bearings.
NF, NJ, and NUH bearings have the ability to withstand axial loads in one direction. The basic structure of the NUH type bearing is a NU type bearing plus retaining ring (L-ring).
Types NH, NP and NUP bearings have the ability to be subjected to bidirectional axial loads.
The NN30 series cylindrical roller bearings with tapered bores are mainly used as radial bearings for machine tool spindles.
NNU49 series double cylindrical roller bearings.
N19, N10 single row cylindrical roller bearings.
SL type
RNU cylindrical roller bearing without inner ring
Judging the fault maintenance method of SKF self-aligning ball bearing in use
SKF bearings exhibit a strong regularity during their use and are very repeatable. Normal high-quality bearings (SKF bearings) have relatively small vibration and noise at the beginning of use, but the spectrum is somewhat scattered and the amplitude is small, which may be due to some defects in the manufacturing process, such as surface burrs.
After a period of motion, the vibration and noise are maintained at a certain level, and the spectrum is very single, only one or two times the frequency. There are very few spectrums above the power frequency, and the state of the self-aligning ball bearings is very stable and enters a stable working period.
After continuing to run, the vibration and noise of SKF bearings begin to increase, and sometimes abnormal sounds appear, but the change of vibration increases slowly. At this time, the bearing kurtness value suddenly reaches a certain value. We believe that SKF bearings are initially faulty at this time.
At this time, it is required to closely monitor the SKF bearing and pay close attention to its changes. After that, the bearing kurtosis value begins to drop rapidly and approaches the normal value, while the vibration and noise begin to increase significantly, and the increase rate begins to accelerate. When the vibration exceeds the vibration standard (such as ISO2372 standard), the bearing kurtosis value also begins. Rapid increase, when both exceed the vibration standard, and the kurtosis value also exceeds the normal value (the available kurtosis is relative to the standard), we believe that the self-aligning ball bearing has entered the late fault production, and it is necessary to repair the equipment in time and replace the SKF bearing.
SKF bearings exhibit late failure characteristics to serious failures (generally bearing damage such as axles, burns, sand cracks, raceways, bead wear, etc.) are not more than one week. The larger the equipment capacity, the faster the speed. The shorter the interval. Therefore, in the actual fault diagnosis of self-aligning ball bearings, once the late fault characteristics are found, the bearing should be judged decisively and the maintenance should be arranged as soon as possible.
The use factors mainly refer to whether the installation adjustment, use and maintenance, maintenance and repair, etc. meet the technical requirements. According to the technical requirements of SKF bearing installation, use, maintenance and maintenance, monitor and check the load, speed, working temperature, vibration, noise and lubrication conditions of the SKF bearing in operation, find the cause and immediately adjust the cause. Make it back to normal.
First of all, when the spindle bearing in the spindle is in operation, it is necessary to fully ensure the lubrication, and the lubricant is periodically added according to the actual use condition, and the oil cannot be cut off for a long time. Therefore, for the user company, it is better to use a better and more suitable spindle lubricant. The new special spindle oil can significantly improve the lubrication performance, extend the oil change interval, extend the service life of the spindle and the self-aligning ball bearing, and also has better anti-rust and anti-corrosion properties.
Secondly, the bearing with reinforced nylon material cage should be used at a temperature lower than 120 °C.
In addition, care should be taken when cleaning and cleaning the spindle to prevent damage and scratching the surface of the roller. To remove the residue of the SKF bearing part as much as possible, it is better to rinse and suck the inside of the ingot to clean the residual oil. Care should be taken to avoid the use of the dumping type to cause the accumulation of cleaning waste to remain in the bearing parts, resulting in problems such as noise and wear failure of the self-aligning ball bearings.
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IKO cam bearing lubrication technique to solve the raceway noise analysis
The source of the rolling sound is caused by the natural vibration of the ferrule after the load. Due to the elastic contact of the ferrule and the rolling body, a nonlinear vibration system is formed. When the lubrication or machining accuracy is not high, the natural vibration associated with this elastic characteristic is excited, and when it is transmitted to the air, it becomes noise. It is well known that even if IKO bearing parts are processed using the most advanced manufacturing techniques in the world, there will always be small geometric errors in the working surface, which will cause small fluctuations between the raceway and the rolling elements to excite the natural vibration of the vibration system.
First, the bearing drip lubrication method
Drip oil lubrication is suitable for the bearing parts that need to be supplied quantitatively to the lubricating oil. The amount of oil to be dripped is preferably every 3-8 seconds. Excessive oil quantity will cause the bearing temperature to increase.
Second, the oil bath lubrication method of cam bearings
Oil bath lubrication is the common lubrication method in most cam bearings and is suitable for lubrication of low and medium speed IKO bearings. A part of the bearing is immersed in the groove, the lubricating oil is brought up by the rotating bearing part, and then flows back to the oil groove oil surface should be slightly lower than the center of the lowest rolling element.
Third, the radiation lubrication of the bearing
The low pressure oil is injected into the bearing through the nozzle by the oil pump, 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 the cage also cause the surrounding air to flow at a relatively high rotational speed. It is difficult to send the lubricating oil to the bearing in a smooth manner. In this case, it is necessary to spray the smooth oil with low-pressure radiation. In the bearing, the position of the nozzle should be placed between the inner ring and the center of the cage.
Fourth, the bearing lubrication method
The oil is pumped to the cam bearing component by an oil pump, and then filtered and cooled by the lubricating oil after the bearing. Because the circulating oil can take away a certain amount of heat and cool the IKO bearing, this method is used for bearing parts with higher rotational speed.
Five, bearing spray lubrication method
The use of boring shrinking air is mixed with smooth oil through a sprayer to create an oil mist. In the radial bearing, the air flow can effectively cool the bearing and prevent the intrusion of impurities. This method is suitable for the smoothness of high speed and low temperature bearing components.
Although the bearing raceway noise is unavoidable, it is possible to use high-precision machining of the working surface of the part, the correct selection of the bearing and the precise use of the bearing to reduce noise and vibration.
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Common quality defects of KOYO imported bearing parts after heat treatment
Common quality defects of KOYO imported bearing parts after heat treatment include: quenching microstructure superheat, underheating, quenching crack, insufficient hardness, heat treatment variant, surface decarburization, soft point.
Overheat
Overheating of the microstructure after quenching can be observed from the rough mouth of KOYO imported bearing parts.
However, in order to correctly judge the degree of overheating, it is necessary to observe the microstructure. If coarse needle-shaped martensite appears in the quenched structure of gcr15 steel, it is quenched and superheated. The formation may be caused by excessive heating of the quenching heating temperature or the heating temperature is too long; or it may be due to the serious banding of the original structure, forming a local martensite needle-like coarse in the low carbon zone between the two zones. Cause local overheating. The retained austenite increases in the superheated structure, and the dimensional stability decreases. Due to the overheating of the quenched structure, the crystal of the steel is coarse, which leads to a decrease in the toughness of the part and a decrease in the impact resistance. The life of the KOYO bearing is also reduced. Excessive heat can even cause quenching cracks.
2. Underheat
Low quenching temperature or poor cooling will produce a tortite structure exceeding the standard in the microstructure, called underheated structure, which will reduce the hardness and sharply reduce the wear resistance, affecting the life of KOYO bearings.
3. Quenching crack
The crack formed by KOYO imported bearing parts due to internal stress during quenching and cooling is called quenching crack. The causes of such cracks are: the heating temperature is too high due to quenching or the cooling is too fast. The thermal stress and the mass of the metal change the tissue stress greater than the fracture strength of the steel; the original defects of the working surface (such as micro cracks or scratches on the surface) or internal defects of the steel (such as slag inclusions, severe non-metallic inclusions) , white spots, shrinkage holes, etc.) stress concentration during quenching; severe surface decarburization and carbide segregation; insufficient firepower or timely tempering after quenching; excessive cold stress caused by previous processes, forged folding, deep Turning tool marks, sharp edges and corners of oil hooks.
4. Heat treatment deformation
KOYO imported bearing parts have thermal stress and tissue stress during heat treatment. These internal stresses can be superimposed or partially canceled. It is complex and variable because it can follow heating temperature, heating speed, cooling method, cooling rate, The shape and size of the part change, so heat treatment deformation is inevitable. Knowing and mastering the changing laws can make the deformation of KOYO imported bearing parts (such as ellipse of the sleeve, large size increase, etc.) in a controllable range, which is conducive to the production. Of course, mechanical collisions during heat treatment can also cause deformation of the part, but this deformation can be reduced and avoided with improved operation.
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Introduction to the cause of corrosion of IKO oil-free bearings and methods for preventing corrosion
Oil-free bearings use water-soluble cutting fluids, and users must work harder on machine maintenance and management to control erosion and even eliminate erosion. In order to prevent water from eroding the metal surface, the machine tool should always be fully lubricated and greased on important parts of the machine tool.
Oil-free bearings can have a long life under accurate use. If the damage is too early, it may be caused by improper selection, improper use or poor lubrication.
Therefore, when installing IKO bearings, we need to record the type of machine, the installation location, the premise of use and the nearby cooperation. Through research to summarize the type of bearing damage, the use environment when the problem occurs, to avoid similar situations happen again.
Correctly control the concentration of the cutting fluid. When the machine is shut down, use the cutting fluid to clean the surface of the machine, and open the machine cover to dissipate the humid air in the working area of the machine. To prevent the occurrence of electrical corrosion, a layer of waterproof grease should be applied to the metal surface. Moreover, the machine tool should be grounded strictly. It is not enough to ground the electrical cabinet only. To avoid the breeding and breeding of bacteria, the cutting fluid should be cleaned or replaced on time, the chips should be removed in time, and soft water (pure water with low mineral content) should be used. Diluted the cutting concentrate.
In addition to excellent quality, oil-free bearings are also very precise parts. They are high-performance bearings. If they are used improperly during use, they will not achieve the expected functional effects, and it will easily damage IKO bearings. I have definitely paid attention to it.
First, the use of the installation should be taken seriously and do not agree to strong stamping, do not answer the application of vertical tapping bearings, do not allow to pass the pressure through the moving body.
Second, use appropriate and correct installation tools to use special tools as much as possible, and try to avoid the use of cloth and short fibers.
Third, try to keep the bearing and its surrounding environment clean. Even if the visible dust that is invisible to the naked eye enters the bearing, it will increase the wear, vibration and noise of the IKO bearing.
Fourth, to prevent the corrosion of IKO bearings When taking the bearings directly by hand, you should wash the liquid on your hands and apply high-quality mineral oil before handling. In the rainy season and summer, pay special attention to rust prevention. Under certain special operating conditions, oil-free bearings can achieve longer life than traditional calculations, especially at light loads. These special preconditions are that when the moving surface (track and moving parts) is effectively separated by a lubricating film and the surface damage caused by the contaminants is restricted. In fact, under the premise of ideal, the so-called permanent IKO bearing life is possible.
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SKF bearings are used correctly and common faults
There are dozens of rolling SKF bearings on the car. SKF bearings are large and small, including almost all common SKF bearing types. The collision and damage of SKF bearings are also common. Since SKF bearings are generally installed inside the mechanism, it is inconvenient to check visually. Only the fault phenomenon can be judged first, and then disassembled and inspected.
The correct use of SKF bearings is a reliable guarantee for reducing SKF bearing failures and extending the life of SKF bearings, including proper installation and proper lubrication. The following describes the requirements for the use of SKF bearings.
1.Removal and assembly of SKF bearings
SKF bearings should be cleaned before installation. When installing, use a special tool to press the auxiliary bearing straight and evenly. Do not hit with a hammer. It is especially forbidden to strike directly on the SKF bearing. When the SKF bearing race and the seat hole are loose, the seat hole should be repaired or the SKF bearing should be replaced. Do not use the method of pitting or padding on the mating surface of the SKF bearing. When the SKF bearing is disassembled, the SKF bearing should be pulled out with a suitable puller. Do not hit the SKF bearing with a chisel or a hammer.
2. Lubrication of SKF bearings
The lubricants commonly used in SKF bearings are both lubricating oil and grease. When the peripheral speed of the shaft is less than 4-5m/s, or the parts of the car that cannot be lubricated with lubricating oil, they are lubricated with grease. The advantage of grease lubrication is that the sealing structure is simple, the grease is not easy to be lost, and the temperature is not affected much. The grease can be used for a long time.
There are two problems to be aware of when using grease. First, select the appropriate grade of grease according to the requirements of the car manual. For example, automotive water pump SKF bearings should not use nano-based grease because of its poor water resistance. Second, the amount of grease added to the SKF bearing should be appropriate. Generally, only 1/2-l/3 of the SKF bearing cavity is filled. Excessive use is not only useless, but also increases the running resistance of the SKF bearing to make it heat up. Special attention should be paid to the SKF bearing of the automobile wheel hub. It is necessary to promote “empty hub lubrication”, that is, only apply an appropriate amount of grease on the SKF bearing. Otherwise, it will not only waste and dissipate heat, but also cause the grease to overflow. May affect braking performance.
Lubricating oil has the advantages of low frictional resistance and heat dissipation, and is mainly used for SKF bearings with high speed and high working temperature. The grade of the lubricating oil should be selected according to the requirements of the automobile manual, and the vehicle maintenance cycle should be replaced in time. After the old oil is released, the mechanism should be cleaned and then new oil should be added. The fuel should be added to the specified marking line or flush with the filling port. (Depending on the specific structure and requirements of the car), it is not allowed to add more.
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Teach you how to prevent INA bearing corrosion
INA bearing corrosion is mainly divided into metal corrosion and human hand sweat, metal corrosion accounts for the majority, in many cases can not be avoided. Hand sweat can also cause INA bearing corrosion, mainly when sweat contact will produce a sweat film on the surface, the interaction will cause electrochemical reaction and lead to corrosion, but can be avoided, such as tools with gloves to take parts.
Metal corrosion mainly includes:
1 surface finish; 2 chemical structure and composition of metal materials; 3 solution composition and pH value of metal surface; 4 environmental medium; 5 ambient humidity and temperature.
Anti-rust pretreatment method:
Keep the surface clean and clean the appropriate method. General chemical treatment cleaning, mechanical cleaning and solvent cleaning methods. After the surface is cleaned, it can be dried by dry compressed air. It can also be dried with a dryer at 120~170 °C, and then dried with a clean gauze.
(1) Spray method
For example, some large-scale anti-rust materials can not be immersed in oil, mainly suitable for thin-layer anti-rust oil or solvent-diluted anti-rust oil, but pay attention to labor and fire protection measures.
(2) Brushing method
When brushing, it is not only necessary to avoid accumulation, but also to prevent leakage. It is generally suitable for some special-shaped products or outdoor construction equipment that do not use soaking or spraying.
(3) immersion method
The oil film thickness can be achieved by controlling the temperature or viscosity of the rust preventive grease. Some small items are immersed in anti-rust grease to adhere a layer of anti-rust grease to the surface.
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What are the ways to control the influence of bearing noise?
Generally speaking, in order to control the noise influence of the rolling bearing, it is necessary to take countermeasures against the root cause of these noises in order to receive the effect of the root cause. The main route is:
(1) Select low noise bearings;
(2) Try to eliminate noise from the application of the bearing,
(3) Avoid resonance with the host and avoid resonance sensitive speed;
(4) When other methods are ineffective, take additional measures for sound insulation and noise reduction.
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Lubrication tips for Swedish SKF bearings
Rust prevention performance
The grease used in the bearing must have an anti-rust effect, and the anti-rust agent is preferably insoluble in water. Grease should have good adhesion to form an oil film on the surface of the steel, even if the grease is filled with water.
Mechanical stability
Grease becomes soft during machining and causes leakage. When there is a vibration application example, grease will be trapped inside the bearing by the bearing housing. If the mechanical stability of the grease is insufficient, the grease will be continuously thrown out of the bearing, which will cause mechanical collapse of the soap structure and destruction of the grease.
Oil seal
Oil seals are necessary to protect bearings and lubricants from external contamination, and no matter whether debris or moisture can penetrate into the bearings to prevent damage. Proper installation and maintenance is an important factor in the longest service life of the bearing. At the same time, attention must be paid to the cleanliness of the bearings, the correctness of the choice of bearings and the selection of appropriate installation and maintenance tools. Bearings must be protected from contaminants and moisture and must be properly installed and lubricated. The design of the bearing arrangement, the condition of the oil seal, the type of lubricant and the lubrication cycle, as well as the special maintenance play an important role.
Mixed grease
Never mix incompatible greases. If two incompatible greases are mixed, the consistency will usually soften and eventually damage may occur due to the loss of grease. If you don't know which type of grease the bearing originally used, you should first remove the old grease inside and outside the bearing to add grease.
Classification of oils and fats
According to temperature and working conditions: grease can be classified according to their allowable working temperature. The consistency and lubricating ability of grease are affected by working temperature. Bearings operating at a certain temperature must choose the correct consistency and good at the same temperature. Lubricating grease. Grease is manufactured in different operating temperature ranges and can be classified into low temperature (LT), medium temperature (MT) and high temperature (HT) greases. At the same time, there is a type of grease called EP (extrusion resistant) or EM (resistant to extrusion and added molybdenum disulfide), with additives to enhance the strength of the lubricant film.
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NTN bearing regular maintenance should pay attention to matters
When the NTN bearing equipment is regularly inspected, operated, and the NTN bearing that was removed during the replacement of the peripheral parts is stopped, it is necessary to determine whether the secondary NTN bearing parts can be reused and the operation status is better or worse. It is also necessary to rush to check and record the NTN bearings and appearance that have been removed. In order to clarify and check the remaining amount of the visited lubricant, the NTN bearing should be cleaned well after sampling.
Secondly, check the raceway surface of the NTN bearing, the condition of the rolling surface and the joint surface, and the damage and abnormal conditions of the truss wear. It is necessary to check the running track of the raceway surface. To determine whether the NTN bearing can be used again, it is necessary to consider the level of damage to the NTN bearing, the mechanical function, the primacy, the operating premise, the inspection cycle, etc.
If the NTN bearing is found to be damaged or abnormal, please find out the cause of the damage caused by the NTN bearing and formulate countermeasures. In addition, the inspection results, if there are the following defects, NTN bearings can no longer be used, the need to change the new NTN bearings.
a. The inner and outer rings, the rolling elements, and any one of the trusses are cracked and fragmented.
b. Any one of the inner and outer rings and the rolling elements are peeled off.
c. The raceway surface, the ribs, and the rolling elements have significant jamming.
d. The truss is severely worn or the rivets are loose and fierce.
e. The raceway surface, rolling elements are rusted and flawed.
f. There are significant indentations and marks on the rolling surface and the rolling elements.
g. There is creep on the inner diameter surface of the inner ring or the outer diameter of the outer ring.
h. Superheated and discolored.
i. Grease seals NTN bearing seals and dust caps are damaged.
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Maintenance and overhaul of SKF imported bearings
1, imported bearing maintenance
In order to maintain the original performance of the imported bearings in good condition for as long as possible, maintenance, overhaul, and accident prevention are required to ensure the reliability of operation and improve productivity and economy.
Maintenance is best carried out on a regular basis in accordance with the operating standards for the mechanical operating conditions. The content includes monitoring of operating conditions, replenishment or replacement of lubricants, and periodic disassembly inspections.
As a maintenance item in operation, there are rotary sounds, vibration, temperature, and state of lubricant of the imported bearings.
2. Inspection of imported bearings
Cleaning of imported bearings: When disassembling the imported bearings for inspection, first record the appearance of the imported bearings, confirm the residual amount of lubricant, and after sampling the lubricant for inspection, wash the bearings. As a cleaning agent, a cleaning agent or kerosene is generally used.
The cleaning of the removed imported bearings is divided into coarse cleaning and fine cleaning, respectively placed in the container, first placed on the bottom of the metal mesh, so that the imported bearings do not directly contact the dirt of the container. During rough cleaning, if the imported bearing is rotated with dirt, it will damage the rolling surface of the imported bearing and should be noted. In the rough cleaning oil, use a brush to remove the grease and the adhesive. After it is almost clean, it is transferred to the fine wash.
Fine washing is to carefully clean the imported bearings while rotating in the cleaning oil. In addition, the cleaning oil should always be kept clean.
Inspection and judgment of imported bearings: In order to judge whether the removed imported bearings can be used, it is necessary to check after the imported bearings are cleaned. Check the raceway surface, the rolling surface, the state of the mating surface, the wear of the cage, the increase in the clearance of the imported bearing, and the damage and abnormality that are irrelevant in dimensional accuracy. For non-separating small ball bearings, use one hand to support the inner ring and rotate the outer ring to check if it is smooth.
Separate imported bearings such as tapered roller bearings can be inspected separately for the rolling surfaces of the rolling elements and the outer ring.
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Limit speed problem of NSK bearings
When many friends purchase NSK bearings, they always ask me a question, which is the limit speed. Today, Xiao Bian will sort out a little bit of knowledge about this and hope to help everyone.
1) Standard (G) class tolerance bearings;
2) The radial bearing only bears the radial load and the thrust bearing only bears the axial load;
3) = 0.1C (C is the basic dynamic load rating of the bearing);
4) rigid NSK inlet bearing housing and shaft;
5) Lubrication and cooling conditions are normal.
When the bearing is operated under the load condition of 0.1C, the contact stress between the rolling element and the contact surface of the raceway increases, causing the bearing working temperature to rise and the performance of the lubricant to deteriorate relatively. Therefore, the limit rotation speed of the bearing will be correspondingly reduce.
For the range of C/=10, since the reduction of the limit rotation speed is small, it can be disregarded, that is, the value is f1=1.
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Thrust ball bearing installation stability maintenance problem solution
When inspecting the thrust ball bearings that have been removed during the regular inspection and operation of TIMKEN bearing equipment and the replacement of peripheral parts, it is necessary to determine in turn whether the secondary bearing parts can be reused and the usage is better. Also carefully investigate and record the removed bearings and appearance. In order to clarify and investigate the remaining amount of lubricant, the bearings should be cleaned well after sampling.
Next, check the raceway surface of the bearing, the condition of the rolling surface and the mating surface, and the wear state of the cage, etc., for damage and abnormality, especially to observe the running track of the raceway surface. To determine whether the bearing can be used again, it is necessary to consider the degree of damage to the thrust ball bearing, machine performance, importance, operating conditions, inspection cycle, etc.
If the bearing is found to be damaged or abnormal, please find out the cause according to the phenomenon of bearing damage and formulate countermeasures. In addition, the inspection results, if there are the following defects, TIMKEN bearings can no longer be used, need to replace the new bearings.
When grease is added to anti-friction bearings, high pressure theory may not be required unless it is used with great care. High pressure can damage bearings and waste grease. Excessive grease can cause high temperatures and create an invisible environment around the bearings. In most applications, ball or roller bearings are fully lubricated if the grease level is between one-third and one-half of the bearing capacity. The excess will usually be wasted by the sealed casing.
1. Are all requirements for the installation surface and installation site?
If there is foreign matter such as iron filings, burrs, dust, etc. in the thrust ball bearing, the bearing will generate noise and vibration during operation, and even damage the raceway and rolling elements. Therefore, before installing the bearings, you must ensure that the mounting surface and the installation environment are clean.
2. Must the bearings be cleaned before installation?
The surface of the bearing is coated with anti-rust oil. You must clean it with clean gasoline or kerosene, and then apply it with clean high-quality or high-speed high-temperature grease.
The effect of cleanliness on TIMKEN bearing life and vibration noise is very large.
But we must remind you that the fully enclosed bearings do not need to be cleaned and refueled.
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Common bearing wear failures and troubleshooting methods
In general, if the bearing is used correctly, it can be used until the fatigue life is reached. However, there will be accidents that are prematurely damaged and cannot be used. This early damage, as opposed to fatigue life, is a quality use limit called a fault or accident. Many of them are caused by inadvertent installation, use, and lubrication, and foreign objects intruding from the outside are insufficiently studied for the thermal effects of the shaft and the outer casing.
Regarding the damage state of the bearing, such as the ferrule of the roller bearing and the jam of the rib, it may be considered as a cause of insufficient lubricant, unsuitability, defects in the oil supply structure, intrusion of foreign matter, bearing installation error, shaft deflection If the song is too big, there will be coincidences of these reasons.
Therefore, it is difficult to know the true cause of the damage by only investigating the bearing damage. However, if you know the mechanical use of the bearing, the conditions of use, the structure around the bearing, and the situation before and after the accident, combined with the damage state of the bearing and several reasons, it can prevent similar accidents from happening again.
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18 reasons why the bearing is ringing
After a long-term summary by the technicians, there are 27 reasons for the bearing to sound. There may be many that we have not encountered before, and will be slowly replenished later.
1. The bearing is mixed with impurities such as sand or carbon particles to act as an abrasive.
2. The bearing is mixed with moisture, acid or paint and other dirt, which acts as a corrosive effect;
3. The clearance of the bearing is too small (the selection is not appropriate);
4. The lubricating oil or grease type is incorrectly selected;
5. Insufficient lubrication (oil level is too low, oil or grease leaks through the seal);
6. The bearing is flattened by the seat hole (the roundness of the seat hole is not good, or the seat hole is not twisted straight);
7. The horn of the bottom of the bearing housing is not flat (resulting in deformation of the seat hole or even cracks in the bearing housing);
8. There are debris in the bearing housing hole (residues, dust particles, etc.);
9. The seal is eccentric (wearing adjacent parts and rubbing);
10. The bearing is subjected to additional loads (the bearing is axially tightened, or there are two fixed end bearings on one shaft);
11. The thermal elongation of the shaft is too large (the bearing is subjected to static and indeterminate axial additional load);
12. The clearance of the bearing is too small, and the rotation is too tight (the tightening sleeve is too tight);
13. The bearing is noisy (caused by the end face of the roller or the slip of the steel ball);
14. The bearing and the shaft are too loose (the diameter of the shaft is too small or the adapter sleeve is not tightened);
15. The shoulder is too large (touching the seal of the bearing and rubbing);
16. The shoulder of the seat hole is too large (the seal of the bearing is twisted);
17. The gap of the labyrinth seal is too small (friction with the shaft);
18. The teeth of the lock washer are bent (wearing the bearing and rubbing);
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How to maintain car bearings?
Car bearing maintenance instructions summary: car bearing maintenance instructions vehicle rated load range work severe overload directly lead to bearing overload bearing early failure more serious cause of vehicle failure personal safety accidents prohibit bearing abnormal impact load periodic inspection bearing use state observe the bearing Whether the part is abnormal or not, the local temperature rises sharply. It is required to periodically quantify the hydrodynamic bearing.
Maintenance methods for automotive bearings:
1. The vehicle should work within the rated load range. If the overload is severe, the bearing will be overloaded directly, which will cause early failure of the bearing. More serious will cause vehicle failure and personal safety accidents;
2. The bearing is prohibited from being subjected to abnormal impact loads;
3. Regularly check the use status of the bearing, pay attention to observe whether there is abnormal sound and partial sharp temperature rise in the bearing part;
4. Regularly or quantitatively add lubricating oil or grease as required;
5, according to the use of the vehicle, at least once every six months to completely replace the lubricant, and carefully check the bearing;
6. Inspection under bearing maintenance condition: Clean the bearing under detachment with kerosene or gasoline, carefully observe whether there is sliding or creeping phenomenon on the inner and outer cylindrical surfaces of the bearing, whether the inner and outer raceway surfaces of the bearing are peeling or pitting, and the rolling elements And whether the cage is worn or deformed, etc., according to the comprehensive inspection of the bearing, to determine whether the bearing can continue to use.
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General steps for maintaining bearing roll neck bearings
1) Track the position of the bearing in the mill and record it. Timken can provide customers with a roll neck bearing maintenance service record card that can be used to record the housing number, roll number, rack number, bearing position on the mill, outer ring bearing area and rolled product tonnage and bearing working hours Number of data. The record card should be updated at any time and is convenient for maintenance personnel to check. The bearing blanks can record bearing measurement data and other test details.
2) Remove the bearing housing from the roll and remove the bearing from the bearing housing. Whether it is to remove the bearing from the bearing housing or to carry out bearing inspections, special lifting methods and tools are required. Timken can provide customers with lifting tools and special lifting methods.
3) Clean the bearings. All flaking, water, residual lubricant and any other contaminants that cause severe wear on the bearings should be removed during the cleaning of the bearings. The cleaning method and cleaning agent used to clean the bearings are determined according to the size of the bearing to be cleaned or the number of bearings. Small bearings or a small number of bearings can be used with kerosene, mineral oil or other commercial solvents. For large bearings or large numbers of bearings, use a neutral oil with a viscosity of 22 cSt (or 100 SUS at 100 °F) at 40 °C in a cleaning tank.
4) Check the bearings, including visual inspections and minor repairs. On the outer surface of the inner ring or the surface of the roller on which the roller can be removed, if a small peeling or skin crack is found, the metal is usually peeled off by a sander and the edge of the peeling surface is polished.
5) The degree of bearing wear should be checked regularly, and the bearing wear can be evaluated by measuring the bearing clearance;
6) Inspect and repair the bearing housing as needed;
7) Put the bearing back into the bearing housing;
8) Inspect and repair the roll neck as needed;
9) Mount the bearing housing with the bearing onto the roll.
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Analysis: bearing clearance rate and application of the matching instrument
First, we must attach great importance to the importance of improving the bearing clearance rate
One of the main quality indicators for bearing matching is radial clearance. Radial clearance refers to the total clearance of the inner and outer ring channels and the rolling elements in the diameter direction.
Therefore, the bearing clearance is not only a major parameter for the qualification of the finished bearing after the qualified finished parts are matched, but also an important factor for the normal operation of the bearing. The clearance value does not meet the technical standards, which will affect the reasonable distribution of the load between the rolling elements. The rotation accuracy, vibration value and life of the bearing will be affected. Therefore, it is undoubtedly important to improve and guarantee the clearance rate of the bearing.
Second, analyze the causal relationship of the radial pass rate
In the process of product quality, once the problem is discovered, it is necessary to find the cause immediately. Using the form of causal analysis, we will analyze the low rate of radial clearance.
There are five major factors affecting the quality of bearing clearance. If materials and environmental factors are not considered for the time being, the influence of the testing instruments, process methods and personnel quality on the quality of the bearing clearance can be mainly analyzed. In the past, the matching method of the inner and outer rings of the bearing and the steel ball is to connect the inner and outer ring channels. The diameter deviation is sorted by the instrument, and a certain inner ring channel diameter size value and an outer ring channel diameter size value are calculated according to the standard clearance, and then the corresponding size copper ball is selected, and after the assembly, the shaft is assembled. Test the upper and lower limit values of the axial clearance to the clearance checker. If the technical requirements are not met, the three will be re-matched. As for the radial clearance value of the bearing, it is known by the axial clearance value, which is difficult to ensure accuracy. Because the measured axial clearance value is only the upper and lower limit values, and the upper and lower limit values are different due to the curvature of the channel and the method of each person, the radial qualification rate of the bearing selected by this method is adopted. It is unstable. When the time is high and the time is low, the number of rework is frequent, and the quality of the product cannot be confirmed.
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Analysis: Key technical processes for bearing surface treatment
1. The main raw materials: ultra-high molecular polyester borane polymer resin; nano-molybdenum disulfide; anti-rust and oil-absorbing nano-group; trace polytetrafluoroethylene and other mixture of nano-powder. All the above raw materials are independently developed by our company and can be produced in small quantities in the laboratory.
2. Uses: Improve the surface anti-rust ability of the bearing; reduce the surface friction coefficient; comprehensive performance of friction and wear resistance.
3. Suggestions for use:
1) Remove the oil from the bearing surface such as rust. 1. Mix with 1% to 3% of the industrial high-efficiency degreasing powder we developed, and put the bearing ring into the liquid to warm it to 70 degrees to 85 degrees. 30 minutes (intermittent stirring), stop heating and wait until the temperature is 40 degrees or so. Dip the bearing ring in water one by one and brush with the brush. In particular, the bearing work surface should be brushed several times. When brushing, the bearing ring can't leave the water surface. Note : This liquid can remove the oil beads floating on the water surface and reuse it once; 2. Rinse twice with water of about 40 degrees, the two rinse waters can be reused; when the oil is heavy, use 3% ratio and re-mixing Wash the liquid twice;
2) Use LM-1198A super concentrated cleaning solution to remove the lubricating oil immersed in the micropores of the bearing phosphating layer, and let the resin be replaced by molybdenum disulfide. The specific method is 0.5%. Proportion and water with cleaning agent to warm to 85 degrees to 99 degrees (drip down the cleaning agent can be connected to cool, remove the floating oil on the surface after the oil beads can be reused once), soak the bearing workpiece in the cleaning agent with a brush, once Rinse twice with water at a temperature above 70 degrees.
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