Analysis of maintenance technology of IKO needle roller bearing with lubrication

    The function of the IKO bearing fit is to make the stationary and rotating rings of the needle bearing and the stationary part (usually the bearing seat) and the rotating part (usually the shaft) of the mounting part, respectively, to achieve the transfer of the load under rotation. And the basic task of defining the position of the motion system relative to the stationary system.
Needle bearings are required to be fixed in three directions, radial, axial and tangential, on the shaft and in the housing. 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.
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 IKO 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 needle roller bearing is easy to install and disassemble, saving labor, time and money.
For heavy loads, the grease with a small penetration should be selected for high pressure, and the oil film strength and extreme pressure performance should be high. When selecting grease according to environmental conditions, calcium-based grease is not easily soluble in water and is suitable for drying and low moisture environments. Commonly used greases for IKO bearings include calcium-based greases, sodium-based greases, calcium-based greases, lithium-based greases, aluminum-based greases, and molybdenum disulfide greases. The amount of grease filled in the needle bearing is suitable for filling 1/2-1/3 of the inner space of the bearing. At high speeds, reducing the grease to 1/3 will increase the temperature rise.
The temperature of the bearing, generally the temperature outside the bearing can be inferred. If the oil hole can directly measure the outer ring temperature of the thin-walled bearing, it is more suitable. Usually, the temperature of the bearing rises slowly as the bearing starts to run, and reaches a steady state after 1-2 hours. The normal temperature of the needle bearing varies with the heat capacity, heat dissipation, speed and load of the machine. If the lubrication and installation parts are suitable, the IKO bearing temperature will rise sharply and abnormal temperature will occur. At this time, it is necessary to stop the operation and take necessary precautions.
The bearing is a kind of precision mechanical support component. The bearing user deeply hopes that the bearing mounted on the main machine will not damage and maintain its dynamic performance within the predetermined service period, but the objective facts are sometimes not satisfactory, sudden bearing failure accident. Will cause significant losses to users. Through a large number of bearing failure analysis studies, the short-life or premature loss of precision of needle roller bearings is due to material defects or improper manufacturing, but to a considerable extent, it is not installed and maintained in strict accordance with the requirements of bearing use. Or improper bearing damage or actual load exceeding the rated load of the thin-walled bearing itself causes abnormal damage to the IKO bearing.
Cracking and spalling of the bearing is caused by the cyclic load of the bearing, and the contact surface is prone to fatigue damage. Therefore, in order to improve the service life of the needle bearing, the bearing steel must have high contact fatigue strength.
Hardness is one of the important qualities of IKO bearing quality, and has a direct impact on contact fatigue strength, wear resistance and elastic limit. The hardness of the thin-walled bearing steel in the state of use generally reaches HRC61~65, so that the needle bearing can obtain high contact fatigue strength and wear resistance.

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Commonly used INA self-aligning ball bearing lubrication inspection method

Clean the surface of the machine before inspection, and then remove the parts around the INA unloading bearing. The oil seal is a very fragile part, so be careful to disassemble it. Do not apply excessive force. Then carefully check the oil seal and its surrounding parts. If it has been shown to be bad, be sure to replace it. A bad oil seal will cause alignment. Ball bearing damage and severe equipment downtime.
Apply a little bit of lubricant to the friction between the two fingers. If there is any contaminant, feel it, or apply a layer of lubricant on the back of the hand, then seal the light.
Oil-lubricated INA bearings are vented with old oil and, if possible, refilled with fresh oil and allowed the machine to spin at low speed for a few minutes. As far as possible, the oil collects residual contaminants and then vents the oil. The oil is preferably filtered before use.
Grease-lubricated bearings should be replaced with a cotton joint to any part of the bearing when replacing the grease, as these residual fibers may wedge between the rolling elements and cause damage, especially It is the application of the small-key ball bearing that needs to pay attention to this problem.
Under some special conditions, a small amount of solid lubricant is added to the grease. For example, adding 3~5% of molybdenum disulfide No. 1 can reduce wear and improve the resistance to pressure and heat.
    Viscosity is an important characteristic of lubricating oil. The viscosity directly affects the fluidity of the lubricating oil and the thickness of the oil film formed between the friction surfaces. The viscosity of the lubricating oil at working temperature is generally 12-15 cst. The higher the speed, the lower the viscosity, and the heavier the load, the higher the viscosity.
Oil lubrication methods include:
a. Oil bath lubrication
Oil bath lubrication is the most common lubrication method. It is suitable for low and medium speed lubrication. A part of the self-aligning ball bearing is immersed in the groove. The lubricating oil is brought up by the rotating parts and then flows back to the oil groove. The oil level should be slightly lower. The center of the lowest rolling body.
b. drip lubrication
Drip oil lubrication is suitable for INA bearing parts that need to supply lubricating oil quantitatively. The amount of oil dripping is generally one drop every 3-8 seconds. Excessive oil quantity will cause the bearing temperature to increase.
c. Circulating oil lubrication
The filtered oil is sent to the parts by an oil pump, and the used lubricating oil is filtered and cooled for use. Since the circulating oil can take a certain amount of heat to cool down, this method is suitable for bearing parts with a higher rotational speed.
d. Spray lubrication
The dry compressed air is mixed with the lubricating oil through a sprayer to form an oil mist. During the spraying, the air flow can effectively lower the temperature and prevent the intrusion of impurities. This method is suitable for the lubrication of high speed and high temperature parts.
e. Injection lubrication
The high-pressure oil is injected through the nozzle by the oil pump, and the injected oil flows into the oil groove through the other end. When the bearing rotates at a high speed, the rolling elements and the cage also cause the surrounding air to form a gas flow at a relatively high rotational speed.
When inspecting self-aligning ball bearings, never expose the bearings to contaminants or moisture. If the work is interrupted, the machine should be covered with a piece of oil-paper plastic or similar material.
If the unshielded INA bearing is cleaned without the need for disassembly, the coated INA bearing should be cleaned with a white spirit and then blown with a lint-free cloth or blown with compressed air. Dry (be careful not to let the bearing assembly start to rotate).
Do not clean the bearing with a sealing cover or dustproof; just wipe the outer surface. If the INA bearing is damaged, it needs to be replaced. It is much more economical to replace the self-aligning ball bearing during the regular downtime maintenance period to damage the selected sudden downtime.

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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.
1) Breakage and defects of bearing components.
2) Peeling of the rolling surface of the raceway.
When the mechanism is running, the part where the one-way 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 temperature of the INA bearing 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 mechanism is too tight (the gap is insufficient); the roller bearing is over-tightened; the bearing race rotates on the shaft or inside the casing; Too large; bearing cage or rolling element fragmentation.
The vibration system consisting of steel, flexibility, mass, damping, etc., determined by the design parameters of the one-way bearing structure, will produce vibrations that are compatible with its mechanics under operating conditions.
The vibration caused by the deviation in the manufacturing process is smaller, and the vibration is smaller. The roundness, waviness and surface roughness of the steel ball surface are the most influential factors on the vibration of each INA bearing component, followed by the shape error and surface roughness of the inner and outer ring channels, and again the roller bearing cleanliness and Lubricant quality, etc.
Operating conditions such as installation conditions, rotational speed, axial load direction, magnitude, etc.

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Rolling noise analysis of NTN bearings

     The rolling sound is due to the rolling of the rolling elements in the raceway when the NTN bearing rotates to excite a smooth and continuous noise, which only attracts attention when its sound pressure level or tone is extremely large. In fact, the sound energy excited by the raceway sound is limited. For example, under normal conditions, the quality of the 6203NTN bearing raceway is 25~27dB. This type of noise is the most typical of single row deep groove ball NTN bearings that can withstand radial loads. It has the following characteristics:
a. Noise and vibration are random;
b. The vibration frequency is above 1 kHz;
c. Regardless of the change in the rotational speed, the main frequency of the noise is almost constant and the sound pressure level increases as the rotational speed increases;
d. When the radial clearance increases, the sound pressure level increases sharply;
e. NTN bearing housing rigidity increases, the lower the total sound pressure level, even if the speed increases, its total sound pressure level does not increase much;
f. The higher the viscosity of the lubricant, the lower the sound pressure level, but for grease lubrication, the viscosity and shape of the soap fiber can affect the noise value.
The source of the rolling sound is caused by the natural vibration of the ferrule after the load. Due to the elastic contact of the ferrule and the rolling body, a nonlinear vibration system is formed. When the lubrication or machining accuracy is not high, the natural vibration associated with this elastic characteristic is excited, and when it is transmitted to the air, it becomes noise. It is well known that even with the most advanced manufacturing techniques used to process NTN bearing parts, there are always small geometric errors in the working surface, which causes small fluctuations between the raceway and the rolling elements to excite the natural vibration of the vibration system.
Although the rolling noise of the NTN bearing is unavoidable, the working surface of the part can be processed with high precision, the NTN bearing is correctly selected and the NTN bearing is accurately used to reduce noise and vibration.

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How INA oil film bearings work

     INA oil film bearing is a radial sliding bearing with lubricating oil as the lubricating medium. Its working principle is: during the rolling process, due to the rolling force, the roller journal is forced to move, INA oil film bearing center and shaft The center of the neck is eccentric, so that the gap between the INA oil film bearing and the journal forms two regions, one is called the divergent zone (the gap gradually increases along the direction of the journal rotation), and the other is called the convergence zone (the direction of rotation along the journal) slowing shrieking). When the rotating journal brings the viscosity of the lubricating oil from the dispersing zone into the convergent zone, the bearing clearance changes from large to small along the direction of the journal rotation, forming an oil wedge to generate pressure in the lubricating oil. The combined force of the pressure at each point in the oil film along the rolling direction is the bearing capacity of the INA oil film bearing. When the rolling force is greater than the bearing capacity, the eccentricity between the center of the journal and the center of the INA oil film bearing increases. In the asymmetry zone, the bearing clearance becomes steeper along the direction of rotation of the journal, the minimum oil film thickness becomes smaller, the pressure inside the oil film becomes larger, the bearing capacity becomes larger, and the bearing center is not balanced, the center of the journal is no longer offset, and the INA oil film The bearing and the journal are completely separated by the lubricating oil, which theoretically forms a full fluid lubrication.
    From the working principle of INA oil film bearings, one of the most important parameters in the INA oil film bearing system is the minimum oil film thickness. If the minimum oil film thickness value is too small, and the metal impurity particles in the lubricating oil are too large, and the outer size of the metal particles is numerically larger than the minimum oil film thickness, the metal particles accompany the lubricating oil through the minimum oil film thickness as if causing metal contact. When it is serious, it will burn tiles. In addition, if the minimum oil film thickness value is too small, when there is an accident such as steel pile, it is easy to cause metal contact between the journal and the INA oil film bearing to cause burnt tile. The minimum oil film thickness value is related to the structural size and material of the INA oil film bearing, the machining accuracy of the related parts, the mounting accuracy of the INA oil film bearing system, the size of the lubricating oil and the rolling force. How INA oil film bearings work

[Chinese bearing net] 4/6/2011 Author: China Bearing Network
     INA oil film bearing is a radial sliding bearing with lubricating oil as the lubricating medium. Its working principle is: during the rolling process, due to the rolling force, the roller journal is forced to move, INA oil film bearing center and shaft The center of the neck is eccentric, so that the gap between the INA oil film bearing and the journal forms two regions, one is called the divergent zone (the gap gradually increases along the direction of the journal rotation), and the other is called the convergence zone (the direction of rotation along the journal) slowing shrieking). When the rotating journal brings the viscosity of the lubricating oil from the dispersing zone into the convergent zone, the bearing clearance changes from large to small along the direction of the journal rotation, forming an oil wedge to generate pressure in the lubricating oil. The combined force of the pressure at each point in the oil film along the rolling direction is the bearing capacity of the INA oil film bearing. When the rolling force is greater than the bearing capacity, the eccentricity between the center of the journal and the center of the INA oil film bearing increases. In the asymmetry zone, the bearing clearance becomes steeper along the direction of rotation of the journal, the minimum oil film thickness becomes smaller, the pressure inside the oil film becomes larger, the bearing capacity becomes larger, and the bearing center is not balanced, the center of the journal is no longer offset, and the INA oil film The bearing and the journal are completely separated by the lubricating oil, which theoretically forms a full fluid lubrication.
    From the working principle of INA oil film bearings, one of the most important parameters in the INA oil film bearing system is the minimum oil film thickness. If the minimum oil film thickness value is too small, and the metal impurity particles in the lubricating oil are too large, and the outer size of the metal particles is numerically larger than the minimum oil film thickness, the metal particles accompany the lubricating oil through the minimum oil film thickness as if causing metal contact. When it is serious, it will burn tiles. In addition, if the minimum oil film thickness value is too small, when there is an accident such as steel pile, it is easy to cause metal contact between the journal and the INA oil film bearing to cause burnt tile. The minimum oil film thickness value is related to the structural size and material of the INA oil film bearing, the machining accuracy of the related parts, the mounting accuracy of the INA oil film bearing system, the size of the lubricating oil and the rolling force.

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Motor assembly and disassembly steps and methods

      Before disassembly, the site should be cleaned, tools should be prepared, and the joints, end caps and casings, bearing caps and end caps should be marked to avoid mistakes during assembly. The general steps for removing the motor are as follows:

      1. Remove the belt or disconnect the coupling pin of the coupling;

      2. Remove the power wiring and grounding wire in the junction box;

      3. Remove the pulley or coupling;

      4. Remove the foot nut and washer;

      5. Remove the front bearing cover;

      6. Remove the front end cover;

      7. Remove the fan blade cover;

      8. Remove the blades;

      9. Remove the rear bearing cover;

      10. Remove the rear end cover;

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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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