Introduce several common maintenance methods after FAG universal joint bearing damage
Usually, our FAG universal joint bearing will be seriously damaged after using it for a period of time. In this case, what should we do? We should find some common methods for daily maintenance of FAG universal joint bearings. We will introduce them today. Several so that everyone can use it later. One-third of the bearing damage is caused by fatigue damage, the other third is due to poor lubrication, and the other third is due to contaminants entering the bearing or improperly installed.
In this case, we have especially experimented with FAG universal joint bearings with increasing temperature. When inspecting FAG universal joint bearings that have been removed during regular maintenance and operation of bearing equipment and replacement of peripheral parts, it is necessary to judge sequentially. Whether secondary bearing parts can be reused and recorded better than bad. Most FAG universal joint bearings are damaged for many reasons, such as excessively small bearing clearances due to previously estimated loads, ineffective seals, and tight fits. Any of these factors have their particular type of damage and leave a special mark of damage.https://www.supplyforever.com/
Operation method for correct and effective adjustment of TIMKEN outer spherical bearing noise
TIMKEN bearings are precision parts and require a very cautious attitude when used. That is, the use of high-performance bearings can not achieve the expected performance if not used properly, and it is easy to damage the outer spherical bearings. Most of the bearings are damaged for many reasons - beyond the original estimated load, non-effective seals, too tight bearing clearance caused by too small bearing clearance. Any of these factors have their particular type of damage and leave a special mark of damage.
Therefore, inspection of damaged bearings can be found in most cases. In general, one-third of TIMKEN bearing damage is caused by fatigue damage, and the other third is due to poor lubrication. The other third is due to contaminants entering the outer spherical bearing or improperly installed.
Therefore, what we want to talk about is how to protect it and extend its service life. Who is unwilling to make the bearing wear-resistant and durable? Unless your nerves have problems (hehe), you should pay attention to the following matters when using bearings:
If the bearing is used improperly during operation, it will cause a series of problems, so we should pay attention to these problems in order to find the problem and solve the problem in time to ensure the normal use of the bearing. Under normal circumstances, the outer spherical bearing should pay attention to the following three major matters during operation.
First, check the condition of the running machine and monitor it to avoid equipment downtime.
Second, if the TIMKEN bearing is insufficiently lubricated or excessively lubricated, the lubricant contains a magazine, the load is too large, the outer spherical bearing is damaged, the gap is insufficient, and the high temperature friction generated by the oil seal is the same.
High temperatures often indicate that the bearing is in an abnormal condition. High temperatures are also detrimental to the lubricant in the bearing. Sometimes bearing overheating can be attributed to the bearing's lubricant. If the bearing is operated for longer than 125 degrees Celsius, it will reduce bearing life.
Factors affecting bearing life and its control
China Bearing Network believes that the early failure modes of rolling bearings mainly include: cracking, plastic deformation, wear, corrosion and fatigue. Under normal conditions, it is mainly contact fatigue. Main intrinsic influencing factors: hardness, strength, toughness, wear resistance, corrosion resistance, internal stress state (outside service conditions).
1. Martensite in hardened steel
High carbon chromium steel original structure: granular pearlite
Quenching + low temperature tempering: quenching martensite M carbon content, which obviously affects the mechanical properties of steel
The carbon content of GCr15 steel quenching M is 0.5% to 0.56%, and the comprehensive mechanical properties with the strongest failure resistance can be obtained.
M: cryptocrystalline martensite, the measured carbon content is the average carbon content.
2. Retained austenite in hardened steel
High carbon chromium steel may contain 8% to 20% Ar (residual austenite) after normal quenching.
The Ar in the bearing parts has advantages and disadvantages, and the Ar content should be appropriate.
The hardness and contact fatigue life of Ar%↑ increase with the peak value, and then the beneficial effect of reducing Ar must be under the stable state of Ar. If it is spontaneously transformed into martensite, the toughness of steel will be drastically reduced. And embrittlement.
When the load of the bearing is small: Ar is slightly deformed, which reduces the stress peak, and strengthens the deformed Ar processing and stress-strain induced martensite transformation. The influence of the increased amount of Ar on the contact fatigue life is reduced. When the load is large: the large plastic deformation of Ar and the local body will locally cause stress concentration and break, thus reducing the life.
3. Undissolved carbides in hardened steel
The amount, morphology, size and distribution of undissolved carbides in hardened steel are affected by the austenitizing conditions due to the chemical composition of the steel and the original microstructure before quenching.
When the load (especially the carbide is non-spherical) and the matrix cause stress concentration and cracks, the toughness and fatigue resistance are lowered.
Quenching of undissolved carbides affects the properties of steel
Affects the carbon content and Ar content and distribution of quenched martensite, which has an additional effect on the properties of steel.
Excessive quenching of undissolved carbides is detrimental to the overall mechanical properties and failure resistance of the steel.
A small amount of undissolved carbides after quenching of the bearing steel is necessary for wear resistance. Fine grained cryptocrystalline martensite is required. The amount of undissolved carbides is small (small quantity), small (small size), and uniform (the sizes are very small, And evenly distributed), round (each carbide is spherical).
Properly reducing the carbon content of bearing steel is one of the ways to improve the service life of parts.
4. Residual stress after quenching and tempering
After quenching and low temperature tempering, the bearing parts still have large internal stress.
When the surface residual compressive stress increases, the fatigue strength increases (excessive residual stress may cause deformation of the part). When the residual internal stress is tensile stress, the fatigue strength is lowered.
5. Impurity content of steel
Impurities: non-metallic inclusions harmful elements (acid soluble), such as the higher the oxygen content, the more oxide inclusions, the influence of impurities in the steel on the mechanical properties and the failure resistance of the parts and the type, nature, quantity and size of the impurities and The shape is usually related to the reduction of toughness, plasticity and fatigue life. For bearing parts working under high stress, the oxygen content of the steel must be reduced. The MnS inclusions in the steel can be wrapped in an ellipsoid shape. Large oxide inclusions have little or even beneficial effect on fatigue life reduction.https://www.supplyforever.com/
High carbon chromium bearing steel
What are the grades, uses and characteristics of high carbon chromium bearing steels? The bearing network will be introduced in detail for everyone.
High carbon chromium bearing steels have high contact fatigue strength and wear resistance. Many grades are fully hardened steels such as GCr15 GCr15SiMn, GCr15SiMo, and 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, and the toughness is good and impact resistant. It is mainly used to manufacture rolling bearing rings and rollers of various sizes and loads.https://www.supplyforever.com/
Prevent premature failure of INA high speed turbine dental drill mobile phone bearings
Regarding the damage state of the high-speed turbine dental drill mobile phone bearing, such as the ferrule of the roller bearing and the framing of the rib, as a cause, the lubricant is insufficient, unsuitable, the defect of the oil supply structure, the intrusion of foreign matter, the bearing installation The error and the deflection of the shaft are too large, and these reasons will coincide.
There are many factors that may affect the service life of INA bearings. The main factors for adjustment are installation, use and maintenance, maintenance, etc., which must meet the technical requirements. According to the technical requirements of the installation, use, maintenance and maintenance of the bearing, the high-speed turbine dental drill mobile phone bearing contact load, speed, lubrication state monitoring and inspection, found that the direct cause of the abnormality is adjusted back to normal.
Mounting conditions, one of the factors used for the bearing is the bearing force that often causes the state change between the parts of the incorrect installation package, the primary factor of the abnormal working temperature of the bearing, vibration, noise, gradual, the quality of the original material is improved. . The proportion of raw material quality factors in INA bearing failure analysis has dropped significantly, but it is still one of the main factors in the failure of high-speed turbine dental drill mobile phone bearings.
The choice of proper or not is still a bearing failure analysis that must be considered. INA bearing manufacturing will pass the forging, heat treatment, turning, lubrication conditions to monitor and check the direct cause of the abnormality found, and the adjustment returns to normal. The installation condition is one of the factors that use the bearing is the primary factor that often causes the change of state between the various parts of the installation package, the main factor in the abnormal operating state, and the early termination of the inner life refers to the structure Design, quality manufacturing processes and materials, three factors determine the quality of high-speed turbine dental drill mobile phone bearings.
Bearings are better than even if the shape becomes a low hum, and knocking noise will occur, which will collide and distract depending on the bearing speed. If intermittent noise is passed. If Sharp's buzz, creaking sounds and other sounds are not in accordance with the rules, often poorly performing bearings reveal and even reverse the situation.
In general, if the INA 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.
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 high-speed turbine drill mobile phone bearing, and understand the situation before and after the accident, combined with the damage state of the INA bearing and several reasons, it can prevent similar accidents from happening again.
Paired angular contact ball bearing
Core Tip: Single row angular contact ball bearings are rarely used alone, usually they are used in two or more sets. High precision mating angular contact ball bearings are commonly used on machine tool spindles with preload. There are three
Single row angular contact ball bearings are rarely used alone, and they are usually used in two or more sets. High precision mating angular contact ball bearings are commonly used on machine tool spindles with preload. There are three different types of pairing: DB back-to-back configuration DF face-to-face configuration DT series configuration There are also freely configurable universal group bearings DU can be back-to-back, face-to-face, and series.
Some common sense to choose and use Timken bearings
1. The size, direction and nature of the Timken bearing load [bearing load capacity is expressed in terms of basic load rating, the value is shown in the bearing size table] Bearing load is rich, such as the size of the load, whether there is only radial load, shaft Whether the load is one-way or two-way, the degree of vibration or shock, and the like. After considering these factors, choose the most suitable bearing type.
In general, the radial load capacity of bearings of the same inner diameter is increased in the following order: deep groove ball bearings < angular contact ball bearings < cylindrical roller bearings < tapered roller bearings < spherical roller bearings
2. The relative inclination analysis of the inner ring and the outer ring causes the Timken bearing inner ring and the outer ring to have relative inclination factors (such as the deflection of the shaft caused by the load, the accuracy of the shaft and the casing, or the installation error), and The type of bearing that is suitable for this type of use. If the relative inclination of the inner ring and the outer ring is too large, the bearing may be damaged by internal load. Therefore, you should choose the type of bearing that can withstand this tilt.
In general, the allowable tilt angle (or centering angle) is incremented in the following order:
Cylindrical roller bearings, tapered roller bearings, deep groove ball bearings (angular contact ball bearings), spherical roller bearings (ball bearings) 3) Bearing type that meets the rigidity required for the mechanical shafting [bearing when the bearing is under load The contact portion between the body and the raceway is elastically deformed. "High rigidity" means that the amount of deformation of such elastic deformation is small.] In the machine tool spindle and the final stage of the vehicle, the rigidity of the shaft must be increased, and the rigidity of the bearing must be increased.
The roller bearing is subjected to load deformation smaller than the ball bearing. Applying a preload (negative clearance) to the bearing increases rigidity. This method is suitable for angular contact ball bearings and tapered roller bearings.
3. The bearing installation space can be accommodated in the bearing installation space. Since the design of the shaft system pays attention to the rigidity and strength of the shaft, the shaft diameter is generally determined first, that is, the inner diameter of the bearing. However, rolling bearings are available in a variety of sizes and types, and the most suitable bearing type should be selected.
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Nsk bearing common troubleshooting method
Due to the inaccurate measurement of the shaft diameter and the bearing housing hole or the roughness of the mating surface does not meet the standard requirements, an excessive interference fit is caused, so that the nsk bearing race is greatly squeezed, resulting in a decrease in the radial clearance of the bearing itself. It makes the bearing difficult to rotate, generates heat, and the wear is intensified or stuck. In severe cases, the inner and outer races of the bearing will be cracked during installation. The non-rotating seat often adopts a gap or a small interference, so that the rotation of the seat may cause a slight creep, and the contact surface of the race with the rolling element is continuously replaced, and the raceway of the race is evenly worn. At the same time, it is also possible to eliminate the axial jam of the rolling elements in the bearing due to the thermal elongation of the shaft. However, if the gap is too large, the non-rotating seat will rotate together with the rolling elements, causing severe wear of the shaft (or the bearing housing hole) and the inner race (or the outer race), and the friction causes the bearing to heat and vibrate.
B. Improper assembly method
When the interference of the nsk bearing and the shaft diameter or the bearing housing hole is small, the press-in method is often used for assembly. The easiest way is to use a copper rod and a hand hammer to symmetrically tap the bearing with an interference fit in a certain order to make the bearing smoothly pressed in. In addition, it is also possible to use a sleeve made of soft metal to be hammered in or pressed by a press. If improperly operated, the seat will be deformed and cracked, or the hammer will be hit on the non-interference fit seat, which will cause the raceway and the rolling element to be indented or the bearing to be indirectly damaged.
C. Improper temperature control during assembly
When the nsk bearing is assembled, if it has a large interference with the shaft diameter, it is usually assembled by hot charging. The bearing is placed in the oil drum filled with organic oil. The outside of the oil drum is heated by hot water or flame. The temperature of the oil required for the process is controlled at 80 ° C ~ 90 ° C, generally not more than 100 ° C, and the maximum is not more than 120 ° C. After the bearing is heated, it is quickly taken out and placed on the journal. If the temperature is not properly controlled, the heating temperature will be too high, which will cause the bearing to temper and the hardness will decrease. The bearing will be prone to wear, peeling and even cracking during operation.
D. Improper gap adjustment during assembly
The gap of the rolling bearing is divided into a radial gap and an axial gap, and its function is to ensure the normal operation and lubrication of the rolling elements and to compensate for the thermal elongation.
For bearings with adjustable clearance, because of the proportional relationship between the axial clearance and the radial clearance, the installation is to adjust the axial clearance to obtain the required radial clearance, and they are generally Used in pairs (ie at both ends or at one end of the shaft), therefore, it is only necessary to adjust the axial clearance of one bearing. Generally, the gasket is used to adjust the axial clearance, and some can also be adjusted by screws or thrust rings.
For nsk bearings whose gaps are not adjustable, the radial clearance is determined according to the standard at the time of manufacture and cannot be adjusted. After such bearings are mounted on the shaft diameter or in the bearing housing bore, the actual radial clearance is called Assemble the radial clearance, and make the radial clearance of the assembly just enough to cause the necessary working radial clearance during operation to ensure the flexible rotation of the bearing. When such a bearing is in operation, the shaft is relatively displaced due to the temperature rise when the temperature rises, so that the radial clearance of the bearing is reduced, and even the rolling elements are caught between the inner and outer races. This can be avoided by leaving an axial gap between one of the double-bearing rolling bearings (the other bearing is fixed on the shaft and in the housing) and the side cover.
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INA roller bearings are maintenance inspection standards
In order to fully utilize INA bearings and maintain their proper performance for a long time, regular maintenance (regular inspection) must be performed. Through proper periodic inspections, early detection of failures and prevention of accidents are important to improve productivity and economy.
Key factors affecting the life of a roller bearing For many rotating machinery products, their service life depends on the life of the bearing components at critical parts of the product. "Maintenance-free" bearings are not one-way bearings that will never be damaged or failed but will not be damaged within a certain period of time. Here the designers calculate the service life of the bearing. The bearing life of the INA bearing is greater than or equal to the overhaul period of the mechanical product. The bearing can be “maintenance free”. When the mechanical product is overhauled, the new bearing can be replaced without using the used bearing. Carry out maintenance.
1, cleaning
When the INA bearing is removed for inspection, the appearance record is first recorded by 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 roller bearings.
2, inspection and judgment
In order to judge whether the removed bearing can be reused, it is important to check its dimensional accuracy, rotation accuracy, internal clearance, mating surface, raceway surface, cage and seal.
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. Roller bearings must not be reused if they are damaged and must be replaced.
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Operation of TIMKEN imported bearings should be regularly maintained
1, grease lubrication
Relubrication of TIMKEN imported 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 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 the bearing. At the same time, care must be taken to maintain the cleanliness of the bearing. 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.
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The inherent and main causes of SKF bearings
1. The small machine can be rotated by hand to confirm whether the rotation is smooth. The inspection items have poor operation due to foreign matter, scratches, and indentations. The installation is poor, the torque generated by the mounting is not stable, and the torque is too large due to too small clearance, installation error, and sealing friction. Wait. If there is no abnormality, the power running can be started.
2, large machinery can not be manually rotated, so immediately after the start of the no-load, the power is cut off, the machine idling, check for vibration, noise, whether the rotating parts are in contact, etc., to confirm that there is no abnormality, enter the power running. The power running starts from the no-load low speed and slowly increases to the rated operation of the specified conditions. The items to be checked during the test run are whether there are abnormal sounds, changes in the temperature of the SKF bearing, leakage or discoloration of the lubricant, and the like. If an abnormality is found, stop the operation immediately, check the machine, and remove the bearing check if necessary.
SKF bearing temperature can generally be estimated based on the external temperature of the housing. However, it is more accurate to directly measure the temperature of the outer ring of the bearing by using the oil hole. The bearing temperature gradually rises from the start of the operation, and the temperature is usually stable after 1 to 2 hours. If the bearing is poorly installed, the temperature will rise sharply and an abnormally high temperature will occur. The reasons are such as excessive lubricant, too small bearing clearance, poor installation, excessive friction of the sealing device, and the like. In the case of high-speed rotation, the selection of SKF bearing structure and lubrication method is also the cause.
The rotation sound of SKF bearings is checked with a stethoscope, etc., and there are strong metal noise, abnormal sounds, irregular sounds, etc. to explain abnormalities. The reasons are poor lubrication, poor accuracy of the shaft or housing, bearing damage, and foreign matter intrusion.
From the two aspects of the reasons for use and internal factors, the reasons for the effectiveness of SKF bearings, the main factors are whether our use is reasonable, the internal factors are actually the level of our choice of bearings! !
The use factors mainly refer to whether the installation adjustment, use and maintenance, maintenance and repair, etc. meet the technical requirements. Installation conditions are one of the primary factors in the use of factors. SKF bearings are often improperly installed, resulting in changes in the force state between the various parts of the bearing, and the bearings operate in an abnormal state and fail early. 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 bearing in operation, find out the cause and immediately adjust the cause, make adjustment It returned to normal. In addition, it is important to analyze the quality of the grease and the surrounding medium and atmosphere.
The internal factors mainly refer to the three major factors that determine the quality of SKF bearings, such as structural design, manufacturing process and material quality. First of all, the structural design is reasonable and advanced, so that it will have a long bearing life. Bearings are generally manufactured through multiple processes such as forging, heat treatment, turning, grinding and assembly. The rationality, advancement and stability of each processing technology will also affect the life of the bearing. The heat treatment and grinding processes that affect the quality of the finished bearing often have a more direct relationship with the failure of the bearing. In recent years, research on the metamorphic layer of bearing working surface shows that the grinding process is closely related to the bearing surface quality.
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The inherent and main causes of SKF bearings
1. The small machine can be rotated by hand to confirm whether the rotation is smooth. The inspection items have poor operation due to foreign matter, scratches, and indentations. The installation is poor, the torque generated by the mounting is not stable, and the torque is too large due to too small clearance, installation error, and sealing friction. Wait. If there is no abnormality, the power running can be started.
2, large machinery can not be manually rotated, so immediately after the start of the no-load, the power is cut off, the machine idling, check for vibration, noise, whether the rotating parts are in contact, etc., to confirm that there is no abnormality, enter the power running. The power running starts from the no-load low speed and slowly increases to the rated operation of the specified conditions. The items to be checked during the test run are whether there are abnormal sounds, changes in the temperature of the SKF bearing, leakage or discoloration of the lubricant, and the like. If an abnormality is found, stop the operation immediately, check the machine, and remove the bearing check if necessary.
SKF bearing temperature can generally be estimated based on the external temperature of the housing. However, it is more accurate to directly measure the temperature of the outer ring of the bearing by using the oil hole. The bearing temperature gradually rises from the start of the operation, and the temperature is usually stable after 1 to 2 hours. If the bearing is poorly installed, the temperature will rise sharply and an abnormally high temperature will occur. The reasons are such as excessive lubricant, too small bearing clearance, poor installation, excessive friction of the sealing device, and the like. In the case of high-speed rotation, the selection of SKF bearing structure and lubrication method is also the cause.
The rotation sound of SKF bearings is checked with a stethoscope, etc., and there are strong metal noise, abnormal sounds, irregular sounds, etc. to explain abnormalities. The reasons are poor lubrication, poor accuracy of the shaft or housing, bearing damage, and foreign matter intrusion.
From the two aspects of the reasons for use and internal factors, the reasons for the effectiveness of SKF bearings, the main factors are whether our use is reasonable, the internal factors are actually the level of our choice of bearings! !
The use factors mainly refer to whether the installation adjustment, use and maintenance, maintenance and repair, etc. meet the technical requirements. Installation conditions are one of the primary factors in the use of factors. SKF bearings are often improperly installed, resulting in changes in the force state between the various parts of the bearing, and the bearings operate in an abnormal state and fail early. 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 bearing in operation, find out the cause and immediately adjust the cause, make adjustment It returned to normal. In addition, it is important to analyze the quality of the grease and the surrounding medium and atmosphere.
The internal factors mainly refer to the three major factors that determine the quality of SKF bearings, such as structural design, manufacturing process and material quality. First of all, the structural design is reasonable and advanced, so that it will have a long bearing life. Bearings are generally manufactured through multiple processes such as forging, heat treatment, turning, grinding and assembly. The rationality, advancement and stability of each processing technology will also affect the life of the bearing. The heat treatment and grinding processes that affect the quality of the finished bearing often have a more direct relationship with the failure of the bearing. In recent years, research on the metamorphic layer of bearing working surface shows that the grinding process is closely related to the bearing surface quality.
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Analysis of the causes and measures for the deterioration of IKO imported bearing grease
The grease used in IKO bearings must have an anti-rust effect, and the anti-rust agent should preferably be insoluble in water. The grease should have good adhesion and form an oil film on the surface of the steel. The grease will become soft during machining and cause leakage. In normal operation, the grease will be transferred from the IKO bearing housing to the IKO bearing. If the mechanical stability of the grease is not enough, 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. If the grease is wrongly selected, all the measures to prevent the IKO bearing are futile. It is important to choose a grease whose base oil viscosity provides sufficient lubrication at the operating temperature. The viscosity is mainly affected by temperature, it decreases with increasing temperature, and it rises when the temperature drops. Therefore, it is necessary to know the viscosity of the base oil at the operating temperature. Mechanical manufacturers often specify the use of certain greases, however most standard greases are available in a wide range of applications.
Grease is critical in the use of IKO bearings. If you use a deteriorated grease, it will not only function as it should, but it will also damage IKO bearings.
1 oil flow observation method
Take two measuring cups, one of which is filled with the lubricating oil to be inspected, the other is placed on the table, and the measuring cup filled with lubricating oil is lifted off the table 30-40 cm and tilted to allow the lubricating oil to slowly flow to the empty cup. In the middle, observe the flow, the quality of the lubricating oil flow should be slender, even, continuous, if the oil flow suddenly and slowly, and sometimes there is a large flow, then the lubricant has deteriorated.
2 handcuffs
The lubricant is rubbed repeatedly between the thumb and the index finger. The better lubricant feels lubricated, less wear debris, and no friction. If you feel a large friction between the fingers, it means lubricating oil. There are many impurities inside, can not be reused, should be replaced with new lubricants.
3 illumination method
On a clear day, use a screwdriver to pry the lubricant at a 45-degree angle to the horizontal. Observe the sunlight and observe the oil droplets. Under the light, it can be clearly seen that there is no wear debris in the lubricating oil, which can continue to work. If the grinding debris is too much, the lubricating oil should be replaced.
4 oil drop trace method
Take a clean white filter paper, drop a few drops of oil on the filter paper. After the oil leaks, if there is black powder on the surface, touch the hand with a feeling of resistance, it means that there are many impurities in the lubricant, good lubricant No powder, it is dry and smooth by hand, and it has yellow marks.
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How to choose the type and type of imported bearings
When selecting SKF bearings, it is necessary to select whether the bearings meet our mechanical use range according to the size, specifications, and speed of the bearings. The following is a simple analysis:
The first is the size limit.
Usually the space in which SKF bearings can be installed is limited. In most cases, the shaft diameter (or bearing inner diameter) is limited by mechanical design or other design. Therefore, the choice of bearing type and size is determined by the inner diameter of the SKF bearing. As a result, the main dimensions of standard SKF bearings are based on the international standard internal diameter dimensions.
Standard SKF bearings are available in a wide range of sizes. It is best to use standard SKF bearings when designing mechanical devices. (This design is easy to purchase from SKF bearings. Here is a question. Some models on the bearing catalogue do have some, but some The SKF bearing is not in stock in mainland China, and sometimes the futures will be for a long time, so the time cost and the cost of later replacement should be taken into account when selecting the bearing. The load of the SKF bearing, the load applied to the bearing, its nature and size. The direction is changeable. Usually, the rated base load is shown on the dimension table. However, axial load and radial load are also important factors in selecting a suitable SKF bearing. When the size of the ball and needle bearing is equivalent, the needle bearing usually has a high load capacity and withstands large vibration and shock loads.
Followed by the speed.
The allowable speed is determined by factors such as the type, size, accuracy, cage type, load, lubrication method, and cooling method of the SKF bearing. The permissible speeds of standard-precision SKF bearings under oil lubrication and grease lubrication are listed on the SKF bearing table. Generally, deep groove ball bearings, self-aligning ball bearings, and cylindrical roller bearings are suitable for high-speed operation.
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Fully installed NTN bearing life and correct bearing method
In principle, all NTN bearings should be kept in their original packaging before installation. They need to be left in a clean, moisture-free, relatively constant temperature environment. Rolling bearings should be kept away from dust, water and corrosive chemicals. Shaking and vibration may permanently degrade the mechanical properties of the NTN bearing, so vibration must be avoided during handling and storage.
Basically, all NTN bearings must be stored horizontally, as some heavier bearings may be deformed by their own weight after standing for a long time.
Pre-coated greased (or sealed) NTN bearings require special care because the density of the grease changes after prolonged storage. Thus, when the NTN bearing is used for the first time, there will be a certain degree of rotational noise. Therefore, the shelf life of such NTN bearings should be controlled on a first-in, first-out basis.
clean
Cleaning is very important for rolling NN bearings. The surface roughness of the rotating surface of the NTN bearing ring and the rolling elements is usually 1/10 μm. Such a smooth surface is very sensitive to damage caused by contaminants. The lubricating layer between the rotating faces is usually 0.2 to 1 μm. Particle-shaped impurities larger than the particle size of the lubricant may be excessively crushed by the rolling elements to cause partial pressure in the NTN bearing steel, which may eventually cause permanent material fatigue. In addition to this, dust particles in the external environment can be up to 10 μm in size, which can also cause damage to NTN bearings. Therefore, a clean, dust-free environment is critical to the storage and installation of the bearings.
NTN bearings should be carefully installed and removed using suitable tools. Industry experts estimate that 16% of premature bearing failures are due to incorrect installation. For large installations (for example in production plants), conditional installations are usually strictly controlled and suitable NTN bearing mounting equipment can be used.
However, in maintenance or replacement work, the environment is diverse. Therefore, in order to ensure the longest service life of the NTN bearing, comprehensive preparation is necessary for bearing installation.
First of all, relevant documents, such as drawings, maintenance manuals, product manuals, etc., need to be carefully studied. Next, all NTN bearing components, such as shafts, spacers, covers, gaskets, etc., must be kept absolutely clean and free from contamination. The status of adjacent components should also be checked carefully.
In order to determine whether the removed NTN bearing can be reused, check the bearing after it has been cleaned. Carefully check the raceway surface, the rolling surface, the state of the mating surface, the wear of the cage, the increase in the NTN bearing clearance, and the presence or absence of damage to the dimensional accuracy. For non-separable miniature ball bearings, use one hand to support the inner ring horizontally and rotate the outer ring to check if it is smooth.
Separate NTN bearings such as tapered roller bearings can be inspected separately for the rolling surfaces of the rolling elements and the outer ring.
Large bearings cannot be rotated by hand. Pay attention to the appearance of rolling elements, raceways, cages, ribs, etc. The higher the importance of NTN bearings, the more careful inspection is required.
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Fault detection analysis of running TIMKEN bearing
It is not uncommon for TIMKEN bearings to malfunction during operation, so there is no need to make a fuss. A fault has occurred, and judgment and processing are the key.
1. The bearing temperature is too high: When the machine is running, the part where the TIMKEN bearing is installed is allowed to have a certain temperature. When the body of the mechanism is touched by hand, it should be normal to not feel hot, otherwise the bearing temperature is too high.
The reasons for the bearing temperature being too high are: the quality of the lubricating oil does not meet the requirements or deteriorates, the viscosity of the lubricating oil is too high; the assembly of the machine is too tight (the gap is insufficient); the bearing assembly is too tight; the bearing race rotates on the shaft or inside the casing; Large; bearing cage or rolling body fragmentation.
2. Bearing noise: TIMKEN bearings allow a slight running noise during operation. If the sound is too loud or there is abnormal noise or impact, it indicates that the bearing is faulty.
The reason for the noise generated by TIMKEN bearings: more complicated, 1) is the wear of the inner and outer rings of the bearing. As a result of this wear, the bearing and the housing, the bearing and the shaft are broken, causing the axis to deviate from the correct position and produce an abnormal sound when the shaft is moving at a high speed. When the bearing is fatigued, the surface metal peeling off will also increase the radial clearance of the bearing to produce abnormal noise. 2) Insufficient bearing lubrication, dry friction, and bearing crushing will produce abnormal sounds. 3) After the bearing wears loose, the cage is loose and damaged, and the abnormal bearing damage will also occur. When the rolling bearing is disassembled and inspected, the bearing failure and the cause of damage can be judged according to the damage of the bearing.
3. Rolling surface metal peeling: TIMKEN bearing rolling elements and inner and outer ring raceways are subjected to cyclic pulsating loads, resulting in cyclically varying contact stresses. When the number of stress cycles reaches a certain value, fatigue peeling occurs on the rolling element or the inner and outer ring raceways. If the bearing load is too large, this fatigue will be exacerbated. In addition, the bearing is not installed correctly, the shaft is bent, and the raceway is peeled off. Fatigue spalling of the bearing races reduces the accuracy of the shaft and causes vibration and noise in the mechanism.
4, bearing burns: burned TIMKEN bearing has a tempering color on the raceway and rolling elements. The causes of burns are generally insufficient lubrication, the quality of the lubricant does not meet the requirements or deterioration, and the bearing assembly is too tight.
5. Plastic deformation: uneven pits appear on the contact surface between the raceway and the roller of the bearing, indicating that the bearing is plastically deformed. The reason for this is that under a large static load or impact load, the local stress of the working surface exceeds the yield limit of the material, which generally occurs on bearings rotating at low speed.
6. Bearing race crack: The cause of the crack in the bearing race may be that the bearing is too tight, the foreign or inner ring of the TIMKEN bearing is loose, the bearing of the bearing is deformed, and the surface of the bearing is poorly processed.
7. The cage is broken: the reason is insufficient lubrication, broken rolling elements, and skewed seat.
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How to tell the quality of KOYO bearing lubricants
Bearing lubricant is the main factor determining whether KOYO bearings can work normally for a long time. How should we distinguish the quality of KOYO bearing lubricants?
First, judge according to color: normal KOYO bearing lubricant is brown and blue black. If it is milky yellow, it means that the lubricating oil is mixed with diesel or water and should be replaced in time. If it is displayed in dark black, it means that the oil has deteriorated and must be replaced in time.
Second, use simple tools: Mix the KOYO bearing lubricant to be evenly distributed and then drop it on white paper (preferably filter paper) to form oil spots. The oil spots will gradually spread from the center for about 2 to 3 hours. Form three concentric rings. The state of the oil can be discerned based on the color, width and shape of the three areas.
Third, according to the feel of the hand: take a little KOYO bearing oil from the oil low shell, apply it on the finger, and use the index finger and thumb to honed. If you feel that there is impurities in the oil or that it is not sticky like water, or even smells astringent or sour, it means that the oil has deteriorated. If you can see the tiny shiny metal grinding on your fingers after honing, it means that the engine has serious wear and tear, and you need to replace the wear parts related to the repair and repair in time.
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Wheel KOYO bearing installation, use common sense
The largest number of wheel bearings for cars used in the past was the use of single row tapered roller or ball bearings in pairs. With the development of technology, car hub units have been widely used in cars. The range and use of hub bearing units is increasing, and has now reached the third generation: the first generation consists of double row angular contact bearings. The second generation has a flange for fixing the KOYO bearing on the outer raceway. The KOYO bearing can be simply placed on the axle and fixed with a nut. Make the maintenance of the car easier. The third-generation wheel bearing unit is equipped with KOYO bearing unit and anti-hold brake system. The hub unit is designed with an inner flange and an outer flange, the inner flange is bolted to the drive shaft, and the outer flange mounts the entire KOYO bearing together.
Worn or damaged wheels KOYO bearings or hub units can cause unsuitable and costly failures in your vehicle's journey, even causing damage to your safety. Please pay attention to the following items during the use and installation of the hub bearing:
1. In order to ensure maximum safety and reliability, it is recommended that you always check the wheel KOYO bearing regardless of the length of the car - pay attention to whether the KOYO bearing has early warning signs of wear: including any friction noise or suspension combination wheel Unnormal deceleration during cornering.
For rear-wheel-drive vehicles, it is recommended to lubricate the front wheel hub KOYO bearing when the vehicle travels to 38,000 km. When replacing the brake system, check the KOYO bearing and replace the oil seal.
2. If you hear the noise from the bearing parts of the hub, first of all, it is important to find the location where the noise occurs. There are many moving parts that may produce noise, or some rotating parts may come into contact with the non-rotating parts. If it is confirmed that the noise is in the KOYO bearing, the KOYO bearing may be damaged and needs to be replaced.
3. Because the working conditions of the front wheel hub causing the failure of KOYO bearings on both sides are similar, it is recommended to replace them in pairs even if only one KOYO bearing is broken.
4, the wheel bearing is more sensitive, in any case need to use the correct method and the right tool. KOYO bearing components must not be damaged during storage and installation. Some KOYO bearings require a large pressure to press in, so special tools are required. Be sure to refer to the car manufacturer's instructions.
5, when installing KOYO bearings should be in a clean and tidy environment, the entry of fine particles into KOYO bearings will also shorten the service life of KOYO bearings. It is very important to maintain a clean environment when replacing KOYO bearings. It is not allowed to hit the KOYO bearing with a hoe. Note that the KOYO bearing should not fall to the ground (or similarly handled improperly). The condition of the shaft and the housing should also be checked before installation. Even slight wear can cause poor fitting and cause early failure of the KOYO bearing.
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Talking about: FAG Cross Roller Bearing Scope
FAG cross-roller bearings can withstand loads from all directions (such as axial, thrust or momentum loads). Since the FAG is in contact with the surface of the track, the bearing is less likely to be elastically deformed by the load.
This type of FAG imported bearings are widely used in industrial robots, work machines and medical facilities. FAG requires high rigidity, tightness and high speed to ensure accurate conditions in cross-roller bearings, because cylindrical rollers are in The 90-degree V-groove rolling surface FAG bearings are arranged perpendicular to each other by spacers, so that one cross-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 extremely thin type is a small size close to the limit and has high rigidity, so it is most suitable for the joint or the rotating part of an industrial robot.
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Method of disassembling a bearing cap of an electric motor
1. The bearing cover is very easy to remove. Just remove the screws that fix the bearing cover and remove the front and rear bearing covers. The front and rear bearing covers should be marked with a mark to avoid mis-assembly before and after assembly.
2. The assembly method of the bearing cover is: insert the outer cover through the rotating shaft outside the end cover, insert a screw, hold the screw with one hand, turn the shaft with one hand, and then turn the bearing inner cover to the outer cover. When the screw holes are aligned, the screws can be inserted into the screw holes of the inner cover and tightened. Finally, the other two screws are also tightened.
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