INA imported bearings damage regular maintenance measures

Rolling bearings, if there is no choice of mistakes can be used correctly, can be used for a long time before the life of INA bearings, in this case, the damage state is peeling.
On the other hand, there are accidental early damage, and early damage that cannot be used, as the cause of the early damage, there is insufficient consideration of the use of scare lubrication, and further foreign matter intrusion, error and shaft of INA imported bearing assembly The deflection is large, and the research on the shaft and the bearing housing is not enough. It can be said that these reasons overlap with each other.
Therefore, in order to fully understand the machine used in the bearing, the conditions of use, and the structure of the outer ring of the INA bearing, if the situation before and after the accident can be clarified, combined with the damage of the bearing and various reasons, it can be prevented. The same kind of accident happened again.
The equipment is inspected regularly, the operation inspection and the bearings removed during the replacement of the peripheral parts are inspected, and the second time is judged whether it can be used again or the use condition is better or worse. The bearings and appearance of the INA bearings that have been removed should be carefully investigated and recorded. In order to clarify and investigate the remaining amount of lubricant, the bearings should be cleaned well after sampling.
Next, check the condition of the raceway surface, the rolling surface and the mating surface, and the wear state of the cage, etc., for damage and abnormality.
Judging whether INA imported bearings can be used again, it is necessary to consider the degree of bearing damage, machine performance, importance, operating conditions, inspection cycle, etc. If the bearing is found to be damaged or abnormal, the contents of the injury section will be identified and the countermeasures will be developed. In addition, the inspection results, if there are the following defects, the bearings can no longer be used, need to replace the new INA bearings.
a. Cracks and fragments appear in any of the inner and outer rings, rolling elements, and cages.
b. Any one of the inner and outer rings and the rolling elements are peeled off.
c. The raceway surface, ribs, and rolling elements are significantly khocked.
d. The cage is worn out or the rivets are loose.
e. The raceway surface, rolling elements are rusted and flawed.
f. There are significant indentations and marks on the rolling surface and rolling elements.
g. Creep on the inner diameter of the inner ring or the outer diameter of the outer ring.
h. Superheated and discolored.
i. Grease seal bearing seals and dust caps are damaged.

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Structure and classification of KOYO imported bearings

Due to the different working conditions of various machines, KOYO bearings have various requirements in terms of load capacity, structure and performance. The KOYO imported bearings developed on the basis of plain bearings are based on rolling friction instead of sliding friction. Generally, two ferrules, a set of rolling elements and a cage are used for versatility, standardization and serialization. A very high degree of mechanical basics. To this end, KOYO bearings need to have a variety of structures. However, the most basic structure consists of the inner ring, the outer ring, the rolling elements and the cage.
The role of various parts in the bearing is:
For a radial bearing, the inner ring is usually tightly fitted to the shaft and operates with the shaft. The outer ring is usually in a transitional fit with the bearing housing or the mechanical housing bore to provide support. However, in some cases, there is also an outer ring running, the inner ring is fixed to support or the inner ring and the outer ring are simultaneously operated. For a thrust bearing, a shaft ring that fits tightly with the shaft and moves together, and a seat ring that is in a transitional fit with the bearing housing or the mechanical housing bore and serves as a support. The rolling elements (steel balls, rollers or needles) are normally arranged in the bearing between the two ferrules by means of a cage for rolling motion. The shape, size and number of the bearings directly affect the bearing capacity and performance of the bearing. In addition to the uniform separation of the rolling elements, the cage can also function to guide the rotation of the rolling elements and improve the lubrication performance inside the bearing.
  1. According to KOYO imported bearing structure type classification
(1) Bearings are classified according to their load direction or nominal contact angle:
        1) Radial bearing----Mainly used for bearing KOYO bearings with radial load, the nominal contact angle is from 0 to 45. According to the nominal contact angle, it is divided into: radial contact bearing----the radial bearing with the nominal contact angle of 0: the radial angular contact bearing---the radial bearing with the nominal contact angle greater than 0 to 45.
        2) Thrust bearings----Mainly used for bearing KOYO bearings with axial load, the nominal contact angle is greater than 45 to 90. According to the different nominal contact angles, they are further divided into: Axial contact bearings----Thrust bearings with a nominal contact angle of 90: Thrust angular contact bearings----Thrust bearings with a nominal contact angle greater than 45 but less than 90.
(2) Bearings are classified according to the type of rolling elements:
        1) Ball bearing ---- rolling element is the ball:
        2) Roller bearing----The rolling element is a roller. Roller bearings are divided into: Roller bearings----rolling elements are cylindrical roller bearings. The ratio of length to diameter of cylindrical rollers is less than or equal to 3; needle roller bearings---- The rolling element is a needle roller bearing, the ratio of the length to the diameter of the needle roller is greater than 3, but the diameter is less than or equal to 5 mm; the tapered roller bearing----the rolling element is the bearing of the tapered roller; the spherical roller bearing one by one The rolling elements are bearings of spherical rollers.
       (3) Bearings can be adjusted according to their work, divided into:
        1) Self-aligning bearing----the raceway is a spherical shape, which can adapt to the angular deviation and angular movement between the two raceway axes;
        2) Non-aligning bearings (rigid bearings)----bearings that can offset the axial angle between the raceways.
       (4) Bearings are divided into: according to the number of rows of rolling elements.

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Maintenance method for static bearing of imported grinding machine in imported bearing

pressure imported bearings with high rotation precision, good steel, high bearing capacity, no wear and high durability. The following are some of the experiences that static pressure imported bearings have explored and tried during the maintenance process.
The static pressure imported bearing has high rotation precision, good steel property, high bearing capacity, no wear and high durability. The following are some of the experiences of static pressure imported bearings in the process of repair and try to obtain, for your reference only.

    1. Small hole throttle:
    (1). Change the internal throttling to external throttling, and add a pressure gauge to instantly display the upper and lower chamber pressure. It is easy to maintain, especially it can be cleaned regularly, which is unmatched by the internal throttle.

    (2). Throttling ratio. The theoretical value of the throttle ratio β is between 1.2 and 1.5, and 1.25 is preferred based on years of experience. In this way, the geometric accuracy of the main shaft, the geometrical accuracy of the front and rear bearing pads, the concentricity, the roundness and the taper need to be strictly controlled in order to ensure the β value. The e value (the eccentricity of the main axis and the geometric center of the bearing bush) is determined according to the load carrying capacity of the machine tool to optimize the β value.

    (3). When the oil chamber is not equipped with the main shaft, the oil column of each oil outlet must be consistent (observation method). If it is inconsistent, the flow rate should be changed by changing the orifice diameter of the restrictor. Taking 4 chambers as an example, the oil column of the lower, left and right chambers is generally between 20 and 25 mm, and the diameter of the small holes is 0.25 to 0.4 mm.

    2. Thin film feedback throttle:

    The film feedback throttling bearing stiffness is very large, but the machine tool often appears to hold the tile, pull the hair, reduce the pressure and so on. The most critical of the film feedback is the film. In practice, the main reasons for the bearing lock and pulling are: 1 plastic deformation of the film; 2 slow feedback. When the external load is abrupt, the shaft and the tile have already rubbed when the film has not reacted; 3 the film is fatigued. The film is used for a long time and fatigue deformation, which is equivalent to changing the feedback parameters.

    Increased film thickness and the use of some fatigue-resistant materials can achieve good results. Generally, a rigid film, a preload, and a gap are reserved. The specific method is: change the 1.4mm thick film to a 4mm thick rigid film, and place a 0.05mm thick tin foil in the lower cavity to adjust the spindle to a position 0.05mm higher than the ideal position. The purpose is to return to the ideal center just after the spindle is stressed (grinding weight, cutting force).

    3. Improvement of the oil supply system:

    In the static pressure inlet bearing oil supply system, in addition to the coarse filter and the fine filter, the other components have a protective effect on the hydrostatic bearing. The oil supply system is improved on the basis of the original system.
    (1). Connect the pressure relay and pressure gauge (originally in front of the accumulator) at the oil outlet behind the throttle plate so that the operator can see the pressure of the chamber and the inlet pressure. When the pressure difference is greater than a certain value, in order to stop immediately, so as to avoid the axle lock. Such as: the inlet pressure 2MPa, the oral pressure 1.2 ~ 1.6MPa, less than 1.2MPa will stop.

    (2). Add digital detection device:

    There is a gap of 0.04~0.05mm between the main shaft of the static pressure imported bearing and the bearing bush. The oil in the process has a certain resistance value. When the change of the resistance value is detected, the gap of the period can be known. Take the main shaft as one pole and the bearing bush as the other pole, and measure its resistance change. This signal is processed and sent to the photoelectric alarm and control system amplifier to control the start and stop of the spindle motor to avoid the friction between the shaft and the tile.

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Analysis of the Causes of Overheated Bearing Temperature in Cryogenic Low Pressure Expander

Core Tip: The expander used in the cryogenic device is a speed turboexpander that transfers energy in response to changes in the velocity of natural gas. High-pressure natural gas is close to isentropic expansion in the expander.
The expander used in the cryogenic device belongs to a velocity turboexpander, which transfers energy in response to changes in the velocity of natural gas. The high-pressure natural gas is close to isentropic expansion in the expander, causing a drop. At the same time, the output work, consume energy, increase the enthalpy drop, reduce the natural gas outlet temperature, and achieve the purpose of refrigeration. The expansion impeller belongs to the radial axial flow reverse radial impeller, the impeller of the coaxial brake centrifugal turbocharger is semi-open, and the expander and supercharger are single. The expander is the main equipment of the cryogenic station refrigeration system, which plays an important role in cooling and recovering energy. The design flow rates of the high and low pressure expanders are 18623/17388 Nm3/h, the rotational speed is 39000/47000r/min, the inlet temperature of the high and low pressure expanders is -69.15/21.55 °C, and the outlet temperature is -105.32/-39.55 °C. Through analysis, the main factors affecting the bearing temperature of the expander are lubricating oil, water cooler, sealing gas, accessory quality, maintenance quality, etc. The oil film thickness of the lubricating oil is the main reason for restricting the bearing temperature, and the bearing temperature is the influence. The key to long cycle and efficient operation of the expander.

    1 Problems with the expansion unit

    In May 2005, the expansion unit showed high bearing temperature and chain shutdown phenomenon for a week (data shown in Table 1), which caused the unit to be in a lower load operation state. The refrigeration negative temperature was around -50 °C, which was far from the designed cooling temperature.

    2 Expander bearing lubrication mechanism

    The lubrication and cooling of the shaft and bearing of the expander are mainly based on lubricating oil. The main function of the lubricating oil is to provide lubrication and cooling for the shaft, bearing and seal. A dynamic pressure oil film of a certain thickness is formed between the journal and the bearing to form an oil film contact, the oil film holds the shaft, the bearing and the shaft are not in direct contact, and the shaft and the bearing are in fluid friction, and the friction factor is small. At the same time, the metal chips and impurities falling off between the friction pairs are taken away by the lubricating oil, which reduces the abrasive wear, removes the heat generated by the friction, and prevents the shaft and the bearing from being too hot to burn the tile.

    3 Low-pressure expander structure and lubricant flow

    The structure of the low-pressure expander is mainly composed of an expander casing, a rotor shaft, an impeller, a bearing, a key, a back bolt, a heat insulation plate, a back pressure seal, a sealing rubber ring, a temperature probe, a vibration probe and the like. The auxiliary system includes a supercharger, a sealed gas system, a cold blowing system, an accumulator, a balancing valve, and the like.

    Lubrication of bearings and shafts of low pressure expanders

    Lubricating oil of L-TSA68 is lubricated. The viscosity index of lubricating oil is 55.08~82.28mm2/s, and the flash point (opening) index is ≥185°C. The lubricating oil process is lubrication of the oil tank-rough filter-oil pump-lubricating water cooler-double filter-line valve-pre-machine filter-shaft and bearing of the expander.

    4 Troubleshooting and analysis

    4.1 Checking the instrumentation system

    Look at the low expansion machine bearing return oil temperature field data and the main control room computer display bearing temperature data comparison, and then with the infrared thermometer to measure the data comparison, the measured data is basically the same, the error is about 2 ° C; check the low expansion machine Temperature probe installation, if the probe is loosely installed or the probe is not linear, it will also affect the data change, re-calibrate the temperature of the field, re-confirm the sensitivity of the instrument probe, and check that no abnormalities are found.

    4.2 Check the oil tank's test indicators, temperature and pressure

    The main factors affecting the bearing temperature in the lubricating oil test index are kinematic viscosity and lightning. When the kinematic viscosity is higher than the standard value, the movement resistance of the oil film between the journal and the bearing is large, and the heat generated by the movement cannot be taken away in time, which is easy to cause the bearing temperature of the low-pressure expander to be high; when the kinematic viscosity is less than the standard value, the journal and the bearing are The thickness of the oil film is thin, and dynamic lubrication cannot be formed. The boundary between the shaft and the bearing is friction. At this time, the friction factor is several times that of liquid lubrication, and the heat generated between the shaft and the bearing is large, which tends to cause high temperature of the low-pressure expander bearing; lubrication The oil lightning is low, the oil film cannot be formed between the journal and the bearing, or the oil film formed is thinned, and the boundary friction between the shaft and the bearing is easy to cause the bearing temperature of the low-pressure expander to be high. The influence of the temperature of the lubricating oil on the bearing in the fuel tank, the temperature of the oil tank is too high (the normal tank temperature is 58 ° C), and the heat exchange area of ​​the lubricating oil water cooler is constant, and the temperature of the lubricating oil is correspondingly high, resulting in the bearing of the low pressure expander. When the temperature rises, the pressure of the tank on the bearing temperature, the pressure of the tank is too high, which directly affects the speed of the lubricating oil returning to the tank, which also easily causes the bearing temperature of the low-pressure expander to rise. Therefore, to ensure that the low-pressure expander bearing temperature is not high, it is necessary to control the lubricating oil test indicators, tank temperature and pressure.

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Misunderstanding of the use of lubricating grease during the repair process

Core tips: 1. Butting when installing the cylinder head gasket Some repairmen prefer to apply a layer of butter on the cylinder head gasket when installing the cylinder head gasket, which is considered to increase the engine's tightness. As everyone knows, doing this
 1. Butter when installing the cylinder head gasket

    Some repairers prefer to apply a layer of butter on the cylinder head when installing the cylinder head gasket, which is considered to increase the engine's tightness. As everyone knows, this is not only useless, but harmful. It is well known that the cylinder head gasket is an important sealing material between the engine block and the cylinder head of the automobile. It not only requires strict sealing of the high temperature and high pressure gas generated in the cylinder, but also must seal the pressure and flow rate through the cylinder head and the cylinder body. Cooling water and oil, it is required to pay special attention to the quality of the seal when disassembling the cylinder head gasket.

    If butter is applied to the cylinder head gasket, when the cylinder head bolts are tightened, a part of the butter will be squeezed into the cylinder water channel and the oil passage. When the butter remaining between the cylinder heads is working in the cylinder, some of the oil will flow into the cylinder due to the high temperature. The other part will burn the coke deposits on the joint surface of the cylinder block and the cylinder head. Under the action of high pressure and high temperature, it is easy to break down or burn through the cylinder head gasket, causing the engine to leak. Therefore, do not apply butter when installing the cylinder head gasket.

    2. Diesel car uses gasoline engine oil

    The oil is divided into gasoline engine oil and diesel engine oil. Although gasoline engines and diesel engines also work under high temperature, high pressure, high speed and high load conditions, there is still a big difference between the two. The compression ratio of the diesel engine is more than twice that of the gasoline engine. The main parts are much more affected by high temperature and high pressure than the gasoline engine, so some parts are made of different materials. For example, the gasoline engine main shaft and the connecting rod bearing bush can be made of babbitt alloy with soft material and good corrosion resistance, while the bearing bush of the diesel engine must be made of high-performance materials such as lead bronze or lead alloy, but the corrosion resistance of these materials Poor performance. For this reason, in the refining process of diesel engine oil, more anti-corrosion agent should be added, so that a protective film can be formed on the surface of the bearing pad to reduce the corrosion of the bearing bush and improve the wear resistance. Since the gasoline engine oil does not have such a preservative, if it is added to the diesel engine, the bearing bush is prone to spots, pits and even the unfavorable consequences of peeling off during use, and the oil will quickly become dirty and cause the shaft to burn. The accident occurred. In addition, the sulfur content of diesel oil is larger than that of gasoline. This harmful substance will form sulfuric acid or sulfurous acid during the combustion process, and together with the high-temperature and high-pressure exhaust gas, it will enter the oil sump to accelerate the oxidation and deterioration of the oil, so the diesel engine oil is refined. Some anti-oxidation additives need to be added during the process to make the oil alkaline. If there is acid gas intrusion, it can play a certain neutralization effect, so as not to cause the oil to oxidize and deteriorate too quickly. The gasoline engine oil does not add this additive because it is neutral. If it is used in a diesel engine, it will quickly deteriorate due to the corrosion of the above acid gas. Therefore, do not use gasoline engine oil to fill the diesel engine.

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Locomotive rolling bearing fault generation and diagnosis method

Core Tips: The locomotive rolling bearing fault generation and diagnosis method summary: Introduce the simple diagnosis and precision diagnosis of the rolling bearing of the locomotive, and enumerate the detection cases. Key words: locomotive rolling import
Locomotive rolling bearing fault generation and diagnosis method

    Abstract: This paper introduces the simple diagnosis and precision diagnosis of locomotive rolling imported bearings, and enumerates the detection cases.

    Key words: locomotive rolling imported bearing fault detection
   
    1 Introduction

    As the main components of the locomotive, especially the traction motor and axle box bearing, the imported function plays a decisive role in the safe transportation. When the locomotive runs on the line, once the bearing fails, the whole train will not run, and the transportation line will be blocked. In particular, the passenger trains fail, and the negative impact is even greater. At the same time, once the locomotive bearings fail, it is very difficult to repair the locomotives. Therefore, preventing and reducing the occurrence of locomotive bearing faults is very dangerous for the safe transportation of locomotives. It is important to be able to detect the bearing with hidden troubles before the bearing is loaded, and to ensure that the qualified bearing accessories are on the car is the focus of this paper.

    2 bearing failure

    Severe damage of the bearing is often not caused by a single cause. However, under a combination of several aspects, a vicious cycle occurs under severe operating conditions, resulting in serious burning of the bearing. Therefore, after an accident, it is often difficult to judge What causes it, it also gives us some difficulties in formulating relevant measures. For the convenience of discussion, we first analyze the causes of bearing failures from several aspects.

    2.1 Abnormal wear of the bearing

    2.1.1 When the bearing is used for a period of time, the bearing inner ring, rolling element, cage, outer ring, raceway, etc. will produce certain defects and scars, resulting in poor lubrication of the bearing, causing heat generation of the bearing, long-term heating, resulting in:

    (1) Dilution of bearing lubricants.

    (2) Accelerate the fatigue of the material and reduce the hardness. Due to the above reasons, a vicious cycle is further formed, and the overheating is accelerated to burn the bearing. Severe bearing inner ring displacement, rolling element out of round, collision heat, and finally welded together. Therefore, when running on the line, if the bearing is found to be severely heated and smokes, do not stop, but keep running to the front station, because the overheated bearing is in a molten state at this moment, once it stops cooling, it can no longer walk and block the positive line.
 
    2.1.2 It is very important for the oil supply maintenance of locomotive bearings, especially for the proper amount of oil to ensure that the bearing has good lubrication. It is easy to cause bearing failure due to lack of oil and excessive oiling. Poor lubrication and heat, more often it is easy to cause stirring and overheating, so it is necessary to properly supply oil during maintenance, and the lubricating grease of the bearing is also very important. Once the oil and other impurities and moisture are dropped, it will affect the normal swimming. Gap and build the necessary oil film.

    2.1.3 The bearing is used for too long, which exceeds the service life of the bearing and is prone to fatigue of the material. The strong impact of the material causes the material to deform, causing the roller and the raceway surface to peel off and crush, resulting in poor lubrication. And the vibration is increased.

    2.2 Installation impact on bearings

    2.2.1 The inner clearance of the inner ring of the bearing does not match the interference of the shaft. It is also easy to cause bearing failure. The interference is large. It is easy to cause the inner ring of the bearing to crack due to excessive tensile stress. The interference is too small. It is easy to cause the inner ring of the bearing to "relax".

    2.2.2 Bearing assembly with improper clearance, it is easy to cause bearing failure, small clearance is easy to cause friction between the roller and the raceway. As the temperature rises, the bearing inner ring, rolling element, cage, outer ring The temperature of the end caps is not the same, there is a temperature difference between them, so the amount of expansion is also slightly different, which causes a further reduction of the matching clearance, and the heat generation of the bearing is added. If the clearance is too large, the vibration of the roller is increased, which aggravates the impact of the roller and the raceway. At the same time, the internal load distribution is uneven, the load bearing roller is reduced, and the central roller load is excessive.

    2.2.3 When assembling the bearing, the bearing is not impacted by the copper hammer, which causes the cage to be deformed. The inner and outer rings of the traction motor bearing are not installed correctly or other reasons cause the axial traverse amount to disappear, causing the bearing shaft to squash.

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Extend the maintenance and maintenance of INA combined bearing life cycle

     After the INA combination bearing has been installed, if it is not carefully aligned, alignment may result in additional loads, friction and vibration of the INA combination bearing. These can accelerate fatigue and reduce bearing life and can damage the life of other machine parts. In addition, increased vibration and friction can greatly increase energy consumption and risk of premature failure.
    In order to fully utilize the 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.
1, cleaning
When the INA combination bearing is removed and inspected, 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 INA combination 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.
2, inspection and judgment
In order to judge whether the removed INA combination bearing can be reused, it is necessary to check its dimensional accuracy, rotation accuracy, internal clearance, mating surface, raceway surface, cage and seal ring.
3. Basic condition monitoring
During use, the basic external conditions of the US INA combined bearing operation are often monitored, such as temperature, vibration and noise measurements. These regular inspections will identify potential problems early and will prevent unexpected machine stops, enabling production plans, increased plant productivity and efficiency.
4, relubrication
During operation, the bearing is required to have the correct relubrication to perfect its performance. The method of bearing lubrication is divided into grease lubrication and oil lubrication. In order to make the bearing function well, first, choose a lubrication method that suits the conditions of use and the purpose of use. Lubricity of oil lubrication predominates if only lubrication is considered. However, grease lubrication has the advantage of simplifying the structure around the bearing.
5, remove
When the bearing will reach its end of life, it should be replaced. Although the bearing can no longer be used, correctly removing the original INA combined bearing and replacing the new bearing in time can promote the service life of the new INA combined bearing. First, the use of a suitable removal tool will help prevent damage to other machine components. Second, improperly removed technology can be hazardous to the operator.

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