Maintenance and repair of FAG bearings and damage countermeasures
At the time of inspection, it is mainly correct to observe whether the rivet head of the bearing is skewed or loosely welded. The welding of the cage is good or bad. Whether the solder joint is too small, there is a problem that the solder is not strong, or the ball is caused by excessive soldering. They are all special places to pay attention to when testing FAG bearings. There are still some issues to be aware of.
Let's share with you the test of the local part of the bearing in years of work experience. First of all, the inspection of the FAG bearing in the environment should be carried out in a light environment, preferably astigmatism, in order to better observe the outside of the FAG bearing and see that there are no cracks and other abnormalities on the surface. For example, wear, scratches and bumps in the mechanical cloud process can cause the FAG bearing device to shift, resulting in poor position of the device, causing flat load and stress concentration, and reducing the accuracy and service life of the molded FAG bearing.
1. FAG bearing maintenance, overhaul, and abnormal handling
In order to maintain the original performance of the bearing in a good condition for as long as possible, it is necessary to maintain, repair, and prevent accidents, 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 contents include monitoring of operating conditions, replenishment or replacement of lubricants, and inspections for periodic disassembly.
As a maintenance item during operation, there are bearing rotation sound, vibration, temperature, lubricant state, and the like.
2. Damage and countermeasures of FAG bearings
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 are not resistant to use. This early damage, as opposed to fatigue life, limits the quality of what is known as 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 FAG bearing, for example, the jam of the ferrule of the roller bearing, as a cause, the lubricant is insufficient, unsuitable, the defect of the oil supply structure, the foreign matter intrusion, the bearing installation error, the 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 investigating only FAG 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.https://www.supplyforever.com/
High carbon chromium bearing steel
1. Grades, characteristics and uses of high carbon chromium bearing steel
High carbon chromium bearing steels have high contact fatigue strength and wear resistance, many grades are fully hardened steels such as GCr15
GCr15SiMn, GCr15SiMo, GCr18Mo. However, since some bearings require good toughness in the core and high hardness on the surface, a hardened bearing steel such as GCr4 has been developed.
1 GCr15 (fully hardened steel) GCr15 is a typical steel grade of high carbon chromium bearing steel, which has high hardness, wear resistance and contact fatigue strength after quenching and tempering. Its hot workability and workability are good, the hardenability is moderate, but the weldability is poor. GCr15 has a large white point sensitivity, but this defect can be eliminated in bearings that are vacuum degassed. It is used to manufacture rolling bearing rings with wall thickness ≤12mm and diameter ≤250mm, or to manufacture cones, cylinders, spherical rollers and all sizes of needles with diameter ≤22mm. It can also be used to make molds, gauges and woodworking tools as well as mechanical parts with high elastic limit and high fatigue strength.
2 GCr15SiMn (highly hardened steel) improves the content of silicon and manganese on the basis of GCr15 steel, so the hardenability, elastic limit and wear resistance are better than GCr15. The rolling bearing parts produced therefrom should not be used above 180 °C. It is used for the manufacture of rolling bearing rings with wall thickness >12mm, outer diameter >120mm, steel balls with diameter >50mm and cones, cylinders, spherical rollers and all sizes of needles with diameter >22mm. Other uses are the same as GCr15.
3 GCr15SiMo (highly hardened steel) increases the silicon content based on GCr15 and adds molybdenum. It has high hardenability, good wear resistance, high fatigue strength and good overall performance. It is suitable for the manufacture of rolling bearing rings and steel balls, rollers and the like in a large size range.
4 GCr18Mo (high-hardenable steel) adds molybdenum with a mass fraction of 0.15%~0.25% on the basis of GCr15, and increases the content of each, so the hardenability and wear resistance are improved. The lower bainite austempering can be performed to achieve hardness and wear resistance similar to martensite quenching, and the impact, fracture toughness and flexural strength of the steel are improved, thereby improving the overall mechanical properties and life of the steel. A rolling bearing ring with a wall thickness of up to 20 mm can be produced, and the size range of the rolling bearing member is also expanded.
5 GCr4 (restricted hardened steel) GCr4 is a low-hardenability rolling bearing steel. It has the properties of GCr15 fully hardened bearing steel and low carbon alloy carburized steel after being heated by volumetric tip and surface quenched and tempered. After quenching, the surface hardness is high, the surface resistance is good, the fatigue resistance is good, the core hardness is only 35~40HRC, the toughness is good and the impact resistance is good. It is mainly used to manufacture rolling bearing rings and rollers of various sizes and loads. Rotating speed.https://www.supplyforever.com/
Impact of vibration and temperature on NTN linear bearings
The scientific maintenance of NTN bearings is of great help to the extension of their life. Then in the process of use, it can be said that the influence of vibration and temperature on the linear bearing is very large. Let us first look at the influence of the vibration of the bearing on the bearing.
Vibration damage to the bearing can be said to be quite sensitive, peeling, indentation, rust, cracks, wear, etc. will be reflected in the NTN bearing vibration measurement. Therefore, the magnitude of the vibration can be measured by using a special linear bearing vibration measuring device (frequency analyzer, etc.), and the specific situation of the abnormality cannot be inferred by the frequency division. The measured values vary depending on the conditions of use of the bearing or the mounting 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.
In the grinding process of FAG bearings, a small amount of energy is consumed in the contact zone between the grinding wheel and the workpiece, and a small amount of grinding heat occurs, forming a part of the grinding zone with a low temperature. Applying the linear heat transfer heat transfer practice formula to derive, calculate or apply the red inner line method and the thermocouple method to test the brake temperature under the test conditions, the temperature of the grinding zone can be as high as 1000-1500 in 0.1~0.001ms. °C. Such a low temperature at the moment is sufficient to cause low-temperature oxidation of the outer surface of the task surface, amorphous structure, low temperature tempering, secondary quenching, and even burn cracking.
(1) Appearance oxide layer
The steel surface under the action of low temperature and the action of oxygen in the air rise to a very thin (20-30 nm) thin layer of iron oxide. It is worth noting that the thickness of the oxide layer is corresponding to the test results of the total thickness of the externally ground enthalpy layer. This explains that the thickness of the oxide layer is indirectly related to the grinding process and is an important marker of the quality of the grinding.
(2) amorphous layer
When the momentary low temperature of the grinding zone causes the workpiece to reach the molten state, the molten metal molecular flow is evenly applied to the task surface, and is cooled by the base metal at a very fast speed to form a very thin layer of amorphous. State organization layer. It has high hardness and toughness, but it is easily removed in fine grinding as long as it is around 10 nm.
FAG bearing supplement code
Core Tip: Common bearing code FAG's bearing code consists of basic code, pre-code and post code. The basic code indicates the basic type, structure and size of the bearing. Preamble code indicates axis
Common bearing code FAG's bearing code consists of basic code, pre-code and post code. The basic code indicates the basic type, structure and size of the bearing. The leading code indicates that the bearing part is placed before the basic code. The post code indicates the supplemental code added after the basic code of the bearing when the bearing structure shape, size, seal, cage, tolerance, clearance, heat treatment, packaging, technical requirements, etc. are changed. 1 Pre-coded The pre-code R is placed directly before the bearing basic code, and the remaining pre-codes are separated from the basic code by small dots. GS—Thrust cylindrical roller bearing race. Example: GS.81112 K – Assembly of rolling elements and cages. Example: K.81108 assembly of thrust cylindrical roller and cage. R – without bearings that separate the inner or outer ring. Example: RNU207 - NU207 bearing without inner ring. WS—Thrust cylindrical roller bearing shaft ring. Example: WS.81112. 2 Post-code The post-code is placed after the base code. When there are multiple sets of post-codes, they should be arranged from left to right in the order of the post-codes listed in the bearing code table. Some post-codes are separated from the base code by small dots. (1) Internal structure A, B, C, D, E internal structural changes Example 1: angular contact ball bearings 7205C, 7205E, 7205B, C-15 degree contact angle, E-25 degree contact angle, B-40 degree contact angle . Example 2: Cylindrical roller, spherical roller and thrust spherical roller bearings N309E, 21309E, 29412E - reinforced design, improved bearing load capacity. VH-roller self-locking full-roller cylindrical roller bearing (the round diameter of the roller is different from the standard bearing of the same type). Example: NJ2312VH (2) External dimensions and external structure of the bearing DA-separable double row angular contact ball bearing with double inner ring. Example: 3306DA DZ-cylindrical outer diameter roller bearing. Example: ST017DZ K-cone hole bearing, taper 1:12. Example: 2308K. K30-cone bore bearing with a taper of 1:30. Example: 24040K30. 2LS- double inner ring, double row cylindrical roller bearing with dust cover on both sides. Example: NNF5026C.2LS.V- internal structure change, double inner ring, dust cover on both sides, full roller double row cylindrical roller bearing. Bearings with snap grooves on the N-outer ring. Example: 6207N. NR-bearing bearing with snap groove and snap ring on the outer ring. Example: 6207NR. N2-contact ball bearing with two stop grooves on the N2-outer ring. Example: QJ315N2. S-outer ring bearing with oil groove and three lubrication holes. Example: 23040 is. Spherical roller bearings with a bearing outer diameter D of 320 mm or more are not marked with S. The X-outer dimensions conform to international standards. Example: 32036X. Z..-Technical conditions for special structures. Arrange sequentially from Z11. Example: Z15-stainless steel bearing (W-N01.3541). The ZZ-roller bearing has two retaining rings that guide the outer ring. (3) Sealing and dustproof RSR-bearings have a sealing ring on one side. Example: 6207RSR. The ZR-bearing has a dust cover on one side. Example: 6207ZR. 2ZR-bearings have sealing covers on both sides. Example: 62072ZR. The ZRN-bearing has a dust cover on one side and a stop groove on the outer ring on the other side. Example: 6207ZRN. The 2ZRN-bearing has a dust cover on both sides and a snap groove on the outer ring. Example: 62072ZRN. (4) Cage and its materials 1) Solid cage. After A or B is placed in the cage designation, A indicates that the cage is guided by the outer ring and B indicates that the cage is guided by the inner ring. F-steel solid cage, guided by rolling elements. FA-steel solid cage with outer ring guide. FAS-steel solid cage with outer ring guide and lubrication groove. FB-steel solid cage with inner ring guide. FBS-steel solid cage with inner ring guide and lubrication groove. FH-steel solid cage, carburized and quenched. H, H1-carburized quenching cage. FP-steel solid window cage. FPA-steel solid window cage with outer ring guide. FPB-steel solid window cage with inner ring guide. FV, FV1-steel solid window holder, after aging, quenching and tempering treatment. L-light metal solid cage, guided by rolling elements. LA-light metal solid cage with outer ring guide. LAS-light metal solid cage with outer ring guide and lubrication groove. LB-light metal solid cage with inner ring guide. LBS-light metal solid cage with inner ring guide and lubrication groove. LP-light metal solid window cage
Detecting the quality of INA bearing lubricants from the noise used in lubrication
The three simplest detection methods for lubricating oil are: oil spot method, color discrimination method and honing method.
Oil spot method:
The oil to be inspected is evenly mixed and dropped on a white paper (preferably a filter paper) to form oil spots, and the oil spots gradually diffuse from the center outward for about 2 to 3 hours to form three concentric rings. The state of the oil can be discerned based on the color, width and shape of the three areas.
Color discrimination method:
Normal is brown and blue black. If it is milky yellow, it indicates that diesel oil or water is added to the oil and should be replaced in time. If it is dark black, it indicates that the oil has deteriorated and must be replaced in time.
Honing method:
Remove a little oil from the low shell of the oil, apply it on your fingers, and rub it with your fingers and thumb. If you feel that there is impurities in the oil or that it is not sticky like water, or even hairy or sour, the oil has deteriorated. If you can see a small shiny metal grinding on your finger after honing, it means that the engine has a serious wear part, and it also means that the oil must be replaced immediately.
1. Low temperature high speed bearing grease
At present, the equipment using INA bearings is becoming more and more refined, and the grease used for bearings must have the following properties:
(1) It has the same operating life as the bearing, prolongs the maintenance cycle, shortens downtime and improves labor productivity.
(2) Under the high speed of dn>5×105, it is necessary to ensure that the motor temperature rises low and does not lick oil, thus reducing power consumption and protecting the motor.
(3) The impurity content is controlled under certain standards to minimize the pollution of equipment noise to the environment.
(4) Guarantee the flexibility of starting and running the bearing under ultra-low temperature working conditions to ensure the minimum output power.
2. General low noise motor bearing grease
In the INA bearing industry, this grease is used in the largest amount, accounting for about 70% of the total grease. Because this type of grease uses a soft, easy-to-filter lithium soap as a thickening agent, using mineral oil as a base oil, it is easy to meet the requirements of low and medium-end bearings to reduce the vibration value. Another advantage is that it has good pumpability, whether it is mechanical fatliquoring or manual grease application.
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Five precautions for the use of imported bearings, five ways to avoid failure
Precautions for use
Rolling bearings make precision parts, so they need to be cautious when using them. They use high-performance imported bearings. If they are not used properly, they can not achieve the expected performance. Therefore, the following items should be used when using bearings:
Keep the bearings and their surroundings clean. Even if the smiling dust that is invisible to the naked eye enters the bearing, it will increase the wear, vibration and noise of the bearing.
Care must be taken when using the installation. Strong stamping is not allowed. It is not allowed to directly hit the bearing with a hammer. It is not allowed to transmit pressure through the rolling elements.
Use suitable and accurate installation tools, try to use special tools, and try to avoid the use of cloth and short fibers.
To prevent the corrosion of imported bearings, when taking the bearing directly by hand, wash the sweat on the hand and apply it with high-quality mineral oil before handling. In the rainy season and summer, pay special attention to rust prevention.
Bearing cooperation
Matching choice
The inner and outer diameters of the rolling bearing are manufactured to standard tolerances. The tightness of the bearing inner ring to the shaft and the outer ring to the seat hole can only be achieved by controlling the tolerance of the journal and the tolerance of the seat hole. The inner ring of the bearing and the shaft are matched by a base hole, and the outer ring of the bearing and the seat hole are made by a shaft.
The correct choice of cooperation must be aware of the actual load conditions, operating temperatures and other requirements of the imported bearings, but it is actually very difficult. Therefore, most of the cases are based on the use of lint selection.
Load size
The amount of over-win between the ferrule and the shaft or casing depends on the size of the load. The heavier load uses a larger over-win, and the lighter load uses a smaller over-win.
1. Bearing channel one-side extreme position peeling
The one-side extreme position spalling of the channel is mainly manifested by a severe spalling band at the interface between the channel and the rib. The cause is that the imported bearings are not installed properly or there is a sudden axial overload during operation. The countermeasure is to ensure that the bearing is installed in place or the free side bearing outer ring is matched to the clearance fit, so that the bearing is compensated when the bearing is overloaded.
2. The bearing channel peels off symmetrically in the circumferential direction
The symmetrical position spalling shows that the inner ring is spalled around the inner ring, and the outer ring is peeled off in a circumferentially symmetric position (ie, the short axis direction of the ellipse). The reason for this is mainly because the outer hole of the outer shell is too large or the two half are separated. This is particularly evident in camshaft bearings for motorcycles. When the bearing is pressed into the outer shell hole of the elliptical ellipse or the two halves of the split outer casing are fastened, the outer ring of the bearing is made elliptical, and the play in the short axis direction is significantly reduced or even negative. Under the action of the load, the inner ring rotates to produce circumferential peeling marks, and the outer ring only produces peeling marks at the symmetrical position in the short axis direction. This is the main reason for the early failure of the bearing. After testing the failure of the bearing, the roundness of the outer diameter of the bearing has been changed from 0.8μm to 27μm. This value is much larger than the radial clearance value. Therefore, it can be confirmed that the bearing is working under severe deformation and negative play, and it is easy to form abnormal sharp wear and peeling at the early stage. The countermeasures taken are to improve the machining accuracy of the outer casing hole or to use the two-half separation structure of the outer casing hole as much as possible.
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Several points of attention for maintaining and testing NTN bearings
1. In the process of using NTN bearings, regular cleaning is very important. How to clean the bearings accurately? When the bearing is first removed for inspection, first use the method of photography to make a good appearance record. Also, verify the amount of lubricant remaining and sample the lubricant before cleaning the bearings.
2. The cleaning of the bearing is divided into rough washing and fine washing, and the metal mesh frame can be placed on the bottom of the used container.
3. When rough washing, clean the grease or adhesive with a brush on the top of the oil. At this time, if the transfer bearing is moved in the oil, the rolling surface is damaged by foreign matter such as foreign matter.
4. When fine washing, slowly shifting the bearing in the oil, it must be forced to stop.
5. The cleaning agent used on weekdays is neutral non-aqueous diesel or petroleum, and sometimes uses warm alkaline liquid according to demand. Regardless of which cleaning agent is used, it is often necessary to filter and clean the cockroach.
6. Immediately after cleaning, apply anti-rust oil or anti-rust grease to the NTN bearing.
In order to make the imported bearings serve the mechanical operation for a longer period of time, it is necessary to perform regular inspections on the NTN bearings on a regular basis. Through the inspection, the problems caused by the mechanical operation can be effectively found, and the problems can be solved satisfactorily. Increased bearing life.
At the time of inspection, it is mainly correct to observe whether the rivet head of the bearing is skewed or loosely welded. The welding of the cage is good or bad. Whether the solder joint is too small, there is a problem that the solder is not strong, or the ball is caused by excessive soldering. They are all special places to pay attention to when testing imported bearings. There are still some issues to be aware of.
Local inspection of the bearing. First of all, the inspection of imported bearings in the environment should be carried out in a light environment, preferably astigmatism, in order to better observe the outside of the bearing and see that there are no cracks and other abnormalities on the surface. For example, wear, scratches and bumps in the mechanical cloud process can cause the bearing device to shift, resulting in poor position of the device, causing flat load and stress concentration, and the accuracy and service life of the molded bearing are reduced.
In addition, the working environment also pays special attention to moisture or contaminants, which are most likely to cause the bearing to rust. The rust is caused by poor installation of the NTN bearing, and early wear and tear, and the bearing will be directly scrapped. Therefore, pay special attention to waterproof and moisture during use.
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Regular lubrication and maintenance of SKF bearings to avoid failure
1, grease lubrication
Relubrication of SKF bearings is best carried out during planned equipment downtime and is periodically replenished, while removing old grease or extruding old grease through the drain. Wipe the grease fittings clean before adding fresh grease. If the bearing housing does not have a grease fitting, the bearing housing cover or end cap should be opened to remove the old grease and, after cleaning, replenish the same type of fresh grease.
2, lubricating oil lubrication
Regularly check the oil level and oil quality of the lubricating oil. Under normal circumstances, the normal oil level should be within the range of 1/3-2/3 of the equipment oil level window or mark. The oil filling method is oil cup, the oil level shown only represents the oil replenishing capacity, and the bearing tank oil level is to meet the operation requirements. The oil level in the oil cup is less than 1/4 of its total volume.
Check and replenish the oil method, take a small amount of lubricating oil as a sample and compare it with fresh oil. The competent unit can consider the oil quality test to ensure the oil quality is qualified. If the sample looks cloudy, it may be the result of mixing with water, which is commonly referred to as oil emulsification. At this point, the lubricant should be replaced.
If the sample is darkened or thickened, it may indicate that the lubricant has begun to carbonize and the old lubricant should be completely replaced. If possible, flush the oil line with fresh oil. When changing the lubricating oil, make sure that the new and old models of the replaced oil are the same and supplement the required oil level.
Use an oil bath type lubrication system. If the oil temperature is below 60 ° C (140 ° F) and the lubricant is not contaminated, replace the lubricant once a year. If the oil temperature is between 60-100 ° C (140-210 ° F), the lubricant needs to be replaced four times a year. If the oil temperature is between 100 and 120 ° C (210-250 ° F), the lubricant needs to be replaced once a month. If the oil temperature is above 120 ° C (250 ° F), the lubricant needs to be replaced once a week.
Proper installation and maintenance are important factors in the normal operation of SKF bearings. At the same time, care must be taken to maintain the cleanliness of the bearings. Bearings must be protected from contaminants and moisture and must be properly installed and lubricated. In addition, the design of the bearing arrangement, the condition of the oil seal, the form of the lubricant and the replacement cycle and the special maintenance also play an important role and must be paid attention to.
Common faults in imported bearings are as follows:
1, tile surface corrosion: spectral analysis found that the concentration of non-ferrous metal elements is abnormal; there are many sub-micron wear particles of non-ferrous metal components in the iron spectrum; lubricating oil moisture exceeds the standard, acid value exceeds the standard.
2, the surface of the journal is strained: there are iron-based cutting abrasive grains or black oxide particles in the iron spectrum, and there is tempering color on the metal surface.
3, the surface corrosion of the journal: Spectral analysis found that the concentration of iron is abnormal, there are many sub-micron particles of iron in the iron spectrum, and the moisture of the lubricating oil exceeds the standard or the acid value exceeds the standard.
4, surface strain: found in the iron spectrum cutting abrasive particles, abrasive particles are non-ferrous metals.
5, fretting wear behind the tile: spectral analysis found that the iron concentration is abnormal, there are many iron components in the iron spectrum sub-micron wear particles, lubricating oil moisture and acid value is abnormal.
Under liquid lubrication conditions, the sliding surface is separated by the lubricating oil without direct contact, and the friction loss and surface wear can be greatly reduced, and the oil film also has a certain vibration absorbing capability.
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FAG needle roller bearing and lubricating oil
The function of the FAG bearing is to make the stationary ring and the rotating ring of the needle bearing and the stationary part (usually the bearing seat) and the rotating part (usually the shaft) of the mounting part are respectively fixed together, thereby transmitting the load under the rotating state. And the basic task of defining the position of the motion system relative to the stationary system.
On the shaft and in the housing, the rolling bearing requires its position to be fixed in three directions: radial, axial and tangential directions. Radial and tangential positioning is achieved by tight fit of the bearing ring. Axial positioning is only used in a few cases; usually axial stops are used, such as end caps and retaining rings. Limited to the clearance range.
FAG bearings should pay attention to the following four points when choosing to cooperate
The circumferential surface of the bearing ring should have good support and uniform force to reduce deformation and give full play to the bearing capacity of the FAG bearing;
The bearing ring cannot slide in the tangential direction in its mating surface, otherwise the mating surface will be damaged;
The free end bearing must be compatible with the length change of the shaft and the housing bore, ie it must have the ability to accommodate the axial position to swim within a certain range;
It is necessary to make the needle roller bearing easy to install and disassemble, saving labor, time and money.
It is very beneficial to make good use of the needle roller bearing. I also hope that everyone will fully consider the above four points when choosing.
For grease-lubricated bearings and oil seals or dust caps on both sides, the FAG bearing seals do not need to be cleaned before installation. Check the size and finishing of the relevant parts.
1, grease lubrication
Relubrication of FAG bearings is best carried out during planned equipment downtime and is periodically replenished, while removing old grease or extruding old grease through the drain. Wipe the grease fittings clean before adding fresh grease. If the bearing housing does not have a grease fitting, the bearing housing cover or end cap should be opened to remove the old grease and, after cleaning, replenish the same type of fresh grease.
2, lubricating oil lubrication
Regularly check the oil level and oil quality of the lubricating oil. Under normal circumstances, the normal oil level should be within the range of 1/3-2/3 of the equipment oil level window or mark. The oil filling method is oil cup, the oil level shown only represents the oil replenishing capacity, and the bearing tank oil level is to meet the operation requirements. The oil level in the oil cup is less than 1/4 of its total volume.
Check and replenish the oil method, take a small amount of lubricating oil as a sample and compare it with fresh oil. The competent unit can consider the oil quality test to ensure the oil quality is qualified. If the sample looks cloudy, it may be the result of mixing with water, which is commonly referred to as oil emulsification. At this point, the lubricant should be replaced.
If the sample is darkened or thickened, it may indicate that the lubricant has begun to carbonize and the old lubricant should be completely replaced. If possible, flush the oil line with fresh oil. When changing the lubricating oil, make sure that the new and old models of the replaced oil are the same and supplement the required oil level.
Use an oil bath type lubrication system. If the oil temperature is below 60 ° C (140 ° F) and the lubricant is not contaminated, replace the lubricant once a year. If the oil temperature is between 60-100 ° C (140-210 ° F), the lubricant needs to be replaced four times a year. If the oil temperature is between 100 and 120 ° C (210-250 ° F), the lubricant needs to be replaced once a month. If the oil temperature is above 120 ° C (250 ° F), the lubricant needs to be replaced once a week.
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Lubrication points during the operation of FAG linear bearings
Mix two incompatible oils and never mix incompatible oils. Usually the consistency will be soft, and finally the damage will be caused by the loss of grease. If you don't know the grease you used in FAG bearings, you should first remove all the original grease and then add a grease to lubricate.
In the process of using linear bearings, we often encounter such a situation. How are these situations formed? How to solve them when they are formed has always been the biggest headache for the technicians of major enterprises. The causes and solutions for the phenomenon of overheating of the bearing during use are explained in detail: The instantaneous high temperature in the grinding zone can be heated to a temperature higher than the tempering heating temperature of the workpiece at a certain depth (10 to 100 nm). In the case where the austenitizing temperature is not reached, as the temperature to be heated is increased, the surface layer will be re-tempered or high-temperature tempered in accordance with the heating temperature, and the hardness will also decrease. The higher the heating temperature, the more the hardness decreases.
In the grinding process, the grinding wheel and the workpiece contact area consume a large amount of energy, generating a large amount of grinding heat, resulting in local instantaneous high temperature in the grinding zone. Using the linear heat transfer heat transfer theoretical formula to derive, calculate or apply the infrared temperature and thermocouple method to measure the instantaneous temperature under experimental conditions, it can be found that the instantaneous temperature in the grinding zone can be as high as 1000-1500 °C in 0.1-0.001 ms. Such instantaneous high temperature is sufficient to cause high temperature oxidation, amorphous structure, high temperature tempering, secondary quenching, and even burn cracking of the surface layer at a certain depth on the working surface.
The surface of the steel under transient high temperature acts on the oxygen in the air and rises into a very thin (20-30 nm) thin layer of iron oxide. It is worth noting that the thickness of the oxide layer is corresponding to the test results of the total thickness of the surface-grinding metamorphic layer. This shows that the thickness of the oxide layer is directly related to the grinding process and is an important indicator of the quality of the grinding.
The grease used in FAG bearings has rust resistance. The performance of rust prevention is mainly based on the solubility of oil, different viscosity and grease formed by different materials, with different levels of anti-volume and anti-rust properties. Generally speaking, the viscosity is large and the fat solubility is poor. The grease is more water-repellent. Even if the grease is filled with water in the linear bearing cavity, it can form a layer of oil film that can resist the appearance of the steel. Because of the low rotation speed of the bicycle, the choice of grease can be relatively high, but the water resistance is very strong. Because the bicycle is often used in car wash, rain, and off-road, it is very important to deal with water, even if it is The slightly viscous grease will not affect the smoothness under low rotation, and once the surface is oxidized, the entire peeling process and aging process will be rapidly intensified.
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The difference between SKF bearing vibration type and common type
The ferrule of the vibrating SKF bearing and the shaft or the seat hole require a certain transition fit or interference fit. When the interference size is SKF bearing under load, the mating surface of the SKF bearing ring on the shaft or the seat hole There is no "squirming" phenomenon on the principle.
First, let's talk about the SKF bearing vibration type. The inner and outer rings and rolling elements of the SKF bearing vibration type use vacuum degassing bearing steel, which has good fatigue resistance. Moreover, the cage is made of aluminum-iron-manganese bronze material, which has high strength, good elasticity and better wear resistance.
Second, let's look at the ordinary type of SKF bearings. SKF bearings are made of ordinary bearing steel for the inner and outer rings and rolling elements. There is also a cage made of zinc brass, which has low strength and poor elasticity.
So, how to choose SKF bearing vibration type or SKF bearing common type? The following three points are available for reference:
1 Fixed load, fixed load is characterized by a synthetic radial load vector and the ferrule is relatively stationary.
2 Rotating load, the characteristic of the rotating load is that the synthetic radial load vector rotates relative to the ferrule.
3 oscillating load and variable load, oscillating load is the load that is synthesized by rotating load much smaller than fixed load. The oscillating load means that the load applied to some ferrules may sometimes be a rotating load, sometimes a fixed load, and sometimes a oscillating load.
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SKF bearing damage causes and maintenance
Not all damaged bearings can be repaired, but for each damaged bearing, the cause and extent of damage must be evaluated to avoid or reduce re-damage before considering repairing or replacing a new bearing. There are many reasons for damage to SKF bearings, such as improper installation, dirt intrusion or moisture intrusion, which are common causes of early damage to many SKF bearings. Analysis of common causes of damage to SKF bearings and corresponding precautions that extend the life of SKF bearings.
A. Improper operation:
Improper installation, operation or disassembly may cause deformation or defect of the cage
Precautions: Use appropriate handling, installation and removal tools
B. Insufficient lubrication:
Insufficient or improper lubrication may result in component scratches or severe bearing deformation
Precautions: Improve the lubrication system and properly replenish or replace the lubricant at regular intervals
C. Rusty and corrosion:
Contact with water can cause the bearing components to erode and rust. Bearings after rust damage may cause spalling during work
Precautions: Regularly check the seal to ensure a good sealing effect and properly store SKF bearings
D. Current:
Powering up the bearing as it rotates may result in grooves or nicks. Improper electrical grounding can cause minor burns when the bearing is stationary
Precautions: Reduce or avoid current flow through the bearings by properly grounding the connections before parts other than SKF bearings
E. External materials:
Abrasion particles contamination and debris intrusion may cause wear, abrasion and dents on the SKF bearing face
Precautions: Remove invading particles and debris, replace lubricant, check sealing system
F. eccentric:
Eccentricity, tilting, or excessive loading can cause geometric stress concentrations or surface spalling
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Choosing IKO bearing grease
The choice of IKO bearing grease is directly related to the stable operation of the equipment. In order to better play the best condition of IKO bearing, IKO bearing grease must be considered from the following aspects:
1, anti-rust performance
The grease used in IKO bearings must have an anti-rust effect, and the anti-rust agent is preferably insoluble in water. Grease should have good adhesion and form an oil film on the surface of the steel.
2, mechanical stability
Grease becomes soft during machining and causes leakage. During normal operation, the grease will be raked from the IKO bearing housing into the IKO bearing. If the mechanical stability of the grease is insufficient, during the operation, the structure of the soap of the grease will mechanically disintegrate, causing the grease to be destroyed, thereby losing the lubricating effect.
3, oil seal
The oil seal is a necessary barrier to protect IKO bearings and lubricants from external contamination. During the operation of IKO bearings, no matter whether debris or moisture can penetrate into the IKO bearing to prevent damage. Proper installation and maintenance is an important factor in the longest service life of IKO bearings. At the same time, attention must be paid to the cleanliness of IKO bearings, the correctness of IKO bearing selection and the selection of appropriate installation and maintenance tools. In addition, IKO bearings must be protected from contamination and moisture and ensure proper installation and lubrication. Therefore, the design of the IKO bearing, the condition of the oil seal, the type of lubricant and the lubrication cycle, and even the special maintenance play the same and important role.
4, mixed grease
Never mix incompatible greases. If two incompatible greases are mixed, the consistency will usually be soft. Finally, IKO bearings may be damaged due to the easy loss of grease. If you don't know which grease IKO bearings originally used, you must completely remove the old grease inside and outside the IKO bearing before adding new grease.
5, the classification of oil
Mainly 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. IKO bearings operating at a certain temperature must be selected correctly at the same temperature. Grease with consistency and good lubrication. Grease is manufactured in different operating temperature ranges and can be roughly classified into low temperature, medium temperature and high temperature greases. At the same time, there is a type of grease called extrusion resistance or extrusion resistance and the addition of molybdenum disulfide, and at the same time, an additive is added thereto to strengthen the strength of the lubricant film.
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Oil film KOYO bearing oil water inferiority and solution
Oil film KOYO bearings should try to improve the sealing structure and prevent water ingress. However, the KOYO bearing of the oil film near the water, especially the KOYO bearing of the oil film of the high-speed wire rolling mill, is inevitable because it is in a dynamic sealing state.
Water enters the oil film KOYO bearing oil, causing some additives to hydrolyze and fail. It may form turbulent flow, destroy the fluid lubrication under normal operation, cause abnormal wear, easily rust the equipment, make the oil emulsified and deteriorate the water separation, oxidation resistance and anti-foaming. In addition, the oxidation products and sludge generated in the use of water and oil form a colloidal oil mass, which may clog the filter.
Only improvements in the sealing structure and the wear resistance of the sealing apron are improved.
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Talking about: Spherical roller bearing performance varies with bearing size
The self-aligning function varies with the bearing size series. Generally, the allowable centering angle is 1 to 2.5 degrees. This type of bearing has a large load capacity. In addition to being able to withstand radial loads, the bearing can withstand the axial load of two-way action. It has good impact resistance, and generally the running speed of the spherical roller bearing is low.
Wuxi is one of the largest production centers for spherical rollers in China. The current production capacity is more than 1.5 million sets. The production range is 21304-21320, 22205-22264, 22308-22364, 23022-23064, 23120-23164, and 23218-23264. ,24022-24064,24128-24164, the cage has five kinds of CA, MB, MA, CC, CTN1; the inner ring has two kinds of straight holes and tapered holes (K); the outer ring has W33 (with oil groove), N (with There are two types of stop grooves; there are various clearance standards to meet customer needs; the tolerance levels are P0 and P6.
After years of development and accumulation, the company has strong technical strength and excellent product quality, and is highly praised by domestic and foreign customers. In the domestic market, it covers more than 30 provinces, municipalities and autonomous regions, and is a power machinery, mining machinery, textile machinery, engineering. Machinery, automotive industry and other supporting services.
Its high-tech extension products include long inner ring spherical roller bearings, thrust spherical roller bearings, spherical roller bearings with sealing rings, and vibrating screen bearings. The company also produces joint bearings, rolling mill bearings, and cylindrical rollers. Bearing, cone roller bearing.
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Analysis of cleaning, overhaul and damage of timken deep groove ball bearings
First of all, some equipments require TIMKEN bearings to be particularly strict with their own clearance problems. If the clearance is too large, even if it is slightly larger, it will easily wear parts of the equipment, so it is only necessary to reduce Clearance to solve this problem, but another problem has arisen, that is, if the clearance is too small, the problem of heat dissipation, if the heat is not properly, it will easily lead to an increase in internal temperature and eventually cause the bearing to overheat and burn!
Secondly, it may be an excessive load (preload is too large). The speed is too high. The play is too small. There is water or other foreign matter invading. If the above two cases are not the case, the accuracy of the shaft and the bearing housing is poor, and the deflection of the shaft is large. Seeing this, I think everyone wants to know the solution. First, we should study the lubricant and lubrication method, choose the TIMKEN deep groove ball bearing lubricant, and its dosage, and correct the bearing selection. Research is to match, bearing clearance and preload, and to improve the seal. Check the accuracy of the shaft and bearing housing. Of course, if you have an expert next to you, let him operate and learn the best!
1, the cleaning of the bearing
When disassembling the lower bearing for inspection, first record the appearance of the deep groove ball bearing, confirm the residual amount of the lubricant, and then wash the bearing after sampling the lubricant for inspection. As a cleaning agent, gasoline and kerosene are commonly used.
The cleaning of the removed bearing is divided into coarse cleaning and fine fine washing. In the container, the metal mesh bottom is placed first, so that the bearing does not directly contact the container. When rough cleaning, if the bearing is rotated with dirt, it will damage the rolling surface of the 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 deep groove ball bearing while rotating in the cleaning oil. In addition, the cleaning oil should always be kept clean.
2. Inspection and judgment of bearings
In order to judge whether the removed bearing can be reused, check the bearing after cleaning, carefully check the raceway surface, the rolling surface, the state of the mating surface, the wear of the cage, the increase of the bearing clearance and whether there is dimensional accuracy. Falling damage, abnormality. For non-separable ball bearings, use one hand to support the inner ring and rotate the outer ring to check if it is smooth.
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The role of bearing cooperation and selection skills
The function of the bearing fit is to consolidate the stationary and rotating rings of the bearing with the stationary part (usually the bearing seat) and the rotating part (usually the shaft) of the mounting part, thereby realizing the transfer of the load and the defined movement in the rotating state. The basic task of the system relative to the position of the stationary system. On the shaft and in the housing, the rolling bearing requires its position to be fixed in three directions: radial, axial and tangential directions. The radial and tangential positioning is achieved by the tight fit of the bearing ring. The axial positioning is only used in a few cases. The axial position is generally limited by axial limit parts such as end caps and retaining rings. Within the clearance range.
Bearings are important accessories in machinery. They can also be said to be mechanical joints. Like our humans, if there is no joint, it will not work. If people have no joints, then what is the role? Then there is no use, the machine is the same, without the bearing, the machine can not be used, so the machine is inseparable from the bearing, leaving the bearing can not survive, it is equivalent to waste. The use of bearings is very complicated. Some rolling bearings need to be used together. This general technician knows the knowledge that we generally don't know. We will introduce the use and requirements of this rolling bearing. Also know the basis of your familiarity with the bearing.
When choosing a fit, you should pay attention to the following four points:
(1) The circumferential surface of the bearing ring should have good support and uniform force to reduce deformation and fully exert the bearing capacity of the bearing.
(2) The ferrule cannot slide in the tangential direction in its mating surface, otherwise the mating surface will be damaged.
(3) The free end bearing must be compatible with the length change of the shaft and the housing bore, that is, it must have the ability to accommodate the axial position to swim within a certain range.
(4) It must be noted that the bearing is easy to install and disassemble, saving labor, time and money.
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Application range of FAG bearing crossed roller bearings
FAG bearing cross-roller bearings can withstand loads from all directions (such as axial, thrust or momentum loads). Since the FAG bearing is in contact with the outer surface of the track, the bearing is subject to load and elastic deformation is small.
This type of FAG imported bearings are commonly used in industrial robots, mission machinery and medical facilities. FAG require high rigidity, tightness and high speed to ensure accurate position in cross-roller bearings, due to cylindrical rollers. The FAG bearings are arranged perpendicular to each other by a distance maintaining device on a 90° V-shaped groove rolling surface, so that one crossed roller bearing can withstand loads in all directions such as radial load, axial load and moment load.
The size of the inner and outer rings is minimized, and the special ultra-thin type is a small size close to the limit and has high rigidity, so it is most suitable for the joint portion or the rotating portion of the industrial robot.
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Five precautions for the use of imported bearings, five ways to avoid failure
Precautions for use
Rolling bearings make precision parts, so they need to be cautious when using them. They use high-performance imported bearings. If they are not used properly, they can not achieve the expected performance. Therefore, the following items should be used when using bearings:
Keep the bearings and their surroundings clean. Even if the smiling dust that is invisible to the naked eye enters the bearing, it will increase the wear, vibration and noise of the bearing.
Care must be taken when using the installation. Strong stamping is not allowed. It is not allowed to directly hit the bearing with a hammer. It is not allowed to transmit pressure through the rolling elements.
Use suitable and accurate installation tools, try to use special tools, and try to avoid the use of cloth and short fibers.
To prevent the corrosion of imported bearings, when taking the bearing directly by hand, wash the sweat on the hand and apply it with high-quality mineral oil before handling. In the rainy season and summer, pay special attention to rust prevention.
Bearing cooperation
Matching choice
The inner and outer diameters of the rolling bearing are manufactured to standard tolerances. The tightness of the bearing inner ring to the shaft and the outer ring to the seat hole can only be achieved by controlling the tolerance of the journal and the tolerance of the seat hole. The inner ring of the bearing and the shaft are matched by a base hole, and the outer ring of the bearing and the seat hole are made by a shaft.
The correct choice of cooperation must be aware of the actual load conditions, operating temperatures and other requirements of the imported bearings, but it is actually very difficult. Therefore, most of the cases are based on the use of lint selection.
Load size
The amount of over-win between the ferrule and the shaft or casing depends on the size of the load. The heavier load uses a larger over-win, and the lighter load uses a smaller over-win.
1. Bearing channel one-side extreme position peeling
The one-side extreme position spalling of the channel is mainly manifested by a severe spalling band at the interface between the channel and the rib. The cause is that the imported bearings are not installed properly or there is a sudden axial overload during operation. The countermeasure is to ensure that the bearing is installed in place or the free side bearing outer ring is matched to the clearance fit, so that the bearing is compensated when the bearing is overloaded.
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Detailed steps for maintenance of TIMKEN imported bearings
In order to fully utilize TIMKEN's imported bearings and maintain their proper performance for a long time, regular maintenance (regular inspection) must be done.
Through proper periodic inspections, early detection of failures and prevention of accidents are important to improve productivity and economy.
1, cleaning
When removing the TIMKEN imported bearings, first take a look at the appearance with photography. Also, verify the amount of lubricant remaining and sample the lubricant before cleaning the bearings.
a. The cleaning of the bearing is carried out by rough washing and fine washing, and a metal mesh frame can be placed on the bottom of the used container.
b. When rough washing, remove the grease or adhesive with a brush or the like in the oil. At this time, if the bearing is rotated in the oil, be careful that the rolling surface will be damaged by foreign matter or the like.
c. When washing finely, slowly rotate the bearing in the oil and carry out it carefully.
The cleaning agent generally used is a neutral non-aqueous diesel oil or kerosene, and a warm alkali liquid or the like is sometimes used as needed. Regardless of which cleaning agent is used, it is often filtered and kept clean.
Immediately after cleaning, apply anti-rust oil or anti-rust grease to the bearing.
2, inspection and judgment
In order to judge whether the removed TIMKEN bearings can be reused, it is necessary to check the dimensional accuracy, rotation accuracy, internal clearance and mating surfaces, raceways, cages and seals.
Regarding the inspection result, it can be judged by a person who is using a conventional bearing or a proficient bearing.
The criteria for judgment vary depending on mechanical properties and importance, inspection period, and the like. Bearings must not be reused if they are damaged and must be replaced.
1) Breakage and defects of bearing components.
2) Peeling of the rolling surface of the raceway.
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