What are the methods for removing common rolling bearings?

Commonly used disassembly methods for rolling bearings are: tapping method, pull-out method, pushing method, and hot-breaking method.

First, the tapping method

The tapping force is generally applied to the inner ring of the bearing. The striking force should not be added to the rolling element and the cage of the bearing. This method is simple and easy, but it is easy to damage the bearing. When the bearing is at the end of the shaft, it is smaller than the inner diameter of the bearing. A copper rod or other soft metal material is placed against the shaft end, and a pad is placed at the lower part of the bearing, and the hammer is gently tapped with a hammer to remove it. Applying this method should pay attention to the position of the pad to be placed properly, and the focus should be correct.

Second, the pull out method

A special puller is used. When disassembling, the bearing will be pulled out slowly as long as the handle is rotated. When the outer ring of the bearing is disassembled, the angle of the two legs of the puller should be opened outwards; when the inner ring of the bearing is removed, the two legs of the puller should be inward and snapped onto the end face of the inner ring of the bearing.

  Precautions:

1. The pull hook of the puller should be hooked on the inner ring of the bearing, and should not be hooked on the outer ring to avoid excessive looseness or damage of the bearing;

2. When using the puller, align the screw to the center hole of the shaft and do not skew. Should also pay attention to the force of the hook and the bearing, do not damage the hook and bearing;

3. Pay attention to prevent the hook from slipping off;

4. The angle of the two legs of the puller is less than 90°.

Third, push method

The bearing is pressed by the press, and the work is stable and reliable without damaging the machine and the bearing. The press has manual pushing, and the mechanical or hydraulic press pushes.

Note: The pressing point of the press should be on the center of the shaft and should not be biased.

Fourth, hot demolition

Used to remove the tight fit bearing. First, the oil heated to about 100 °C is poured into the bearing to be dismantled. After the bearing ring is thermally expanded, the bearing can be pulled out with a puller.

  Precautions:

1. First, the puller should be installed on the bearing to be removed and a certain pulling force should be applied;

2. Before heating, the shaft should be wrapped with asbestos rope or thin iron plate to prevent the shaft from being swollen by heat. Otherwise, it will be difficult to disassemble. When the bearing is removed from the bearing housing hole, only the bearing housing hole can be heated and cannot be heated. Bearing

3. When pouring oil, the oil pot should be smoothly poured on the bearing ring or the rolling element, and an oil basin should be placed under it to collect the hot oil flowing down to avoid waste and burns;

4. Operators should wear asbestos gloves to prevent burns.

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Causes, phenomena and treatment methods of bearing temperature rise

1. Reasons for the increase in bearing temperature:

    (1). Bearing cooling water is interrupted.

    (2). The oil quality is degraded, the oil itself is not clean or the oil is degraded during operation. If the water in the oil increases, the acidity of the oil will increase, the lubricating effect of the oil will be reduced, the bearing bush will be corroded, and the bearing temperature will rise.

    2. Phenomenon:

    (1). There is an alarm bell ringing.

    (2). The machine side water wheel mechanical fault light plate is on, the temperature of the instrument indicating the bearing temperature rises, and the signal relay operates.

    (3). Thermometer disk (inflated thermometer) The black needle and the yellow needle overlap or exceed the yellow needle.

    (4). A fault signal that raises the bearing temperature.

    3. Processing

    When the bearing temperature rises, first judge whether it is malfunctioning. If it does rise, it should be treated as follows:

    (1). Check the cooling water pressure, water flow and piping system is normal. If the water pressure is low, the filter may be clogged and cannot be disposed of in time. It can be shut down and put into use when it is confirmed that it can work.

    (2). Check the oil pressure of the governor. If the oil pressure is low, the cooling water hydraulic valve may be closed.

    (3). Check if the bearing has abnormal sound and check if the bearing swing is abnormal.

    (4). Observe the oil sample to see if there is any change in the oil color, and test it to see if it has deteriorated. If deterioration is confirmed, stop replacing the new oil.

    (5). Check if the oil level is normal. If it is not normal, check if the oil drain valve is closed. If it is closed, it should be replenished. If the gasket is oily, it should be stopped.

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Locomotive rolling bearing fault generation and diagnosis method

 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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Bearing housing model size

Vertical bearing housing:

SNL vertical bearing housing, large SNL bearing housing, SDG vertical bearing housing, SONL vertical bearing housing, SAF vertical bearing housing, SDAF vertical bearing housing

Integral bearing housing:

SBD vertical bearing, TVN vertical bearing, TN vertical bearing

Flanged housing:

FNL series flanged housing 7225 (00) series flanged housing, I-1200 (00) flanged housing

The bearing size model details table:

Bearing housing model: P305; basic size (mm): 62; weight (kg): 0.90; applicable bearing housing model: UC305;

Bearing housing model: P306; basic size (mm): 72; weight (kg): 1.10; applicable bearing housing model: UC306;

Bearing housing model: P307; basic size (mm): 80; weight (kg): 1.95; applicable bearing housing model: UC307;

Bearing housing model: P308; basic size (mm): 90; weight (kg): 2.20; applicable bearing housing model: UC308;

Bearing housing model: P309; basic size (mm): 100; weight (kg): 3.30; applicable bearing housing model: UC309;
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Radial thrust bearing specification sheet:

GB 273.1 Rolling bearings Tapered roller bearing dimensions;

GB 273.2 Rolling bearings Thrust bearing dimensions scheme;

GB 273.3 Rolling bearings Radial bearing dimensions scheme;

GB 276 rolling bearing deep groove ball bearing dimensions;

GB 281 rolling bearing, self-aligning ball bearing dimensions;

GB 283 rolling bearing cylindrical roller bearing dimensions;

GB 285 rolling bearing double row cylindrical roller bearing dimensions;

GB 288 rolling bearing Spherical roller bearing dimensions;

GB 290 rolling bearing dimensions of drawn cup needle roller bearings;

GB 292 radial bearing angular contact ball bearing dimensions;

GB 294 radial bearing four-point contact ball bearing dimensions;

GB 296 rolling bearing double row angular contact ball bearing dimensions;

GB 296 rolling bearing tapered roller bearing dimensions;

GB 296 rolling bearing flat bottom thrust ball bearing dimensions;
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Bearing maintenance, cleaning, overhaul, lubrication and installation

First, the cleaning of the bearing

When disassembling the lower bearing for inspection, first record the appearance of the bearing, confirm the residual amount of the lubricant, and then wash the bearing after sampling the lubricant for inspection. As a cleaning agent, gasoline and kerosene are commonly used.
The cleaning of the removed bearings is divided into coarse cleaning and fine cleaning. They are placed in the container respectively, and the metal mesh bottom is placed first so that the bearing does not directly contact the container. In rough cleaning, if the bearing is rotated with dirt, it will damage the rolling surface of the bearing and should be noted. In the rough cleaning oil, use a brush to remove the grease and the adhesive. After it is almost clean, it is transferred to the fine wash.
Fine washing is to carefully clean the bearing while rotating it in the cleaning oil. In addition, the cleaning oil should always be kept clean.
Bearing inspection and judgment: In order to judge whether the removed bearing can be used, it should be checked after the bearing is cleaned. Check the raceway surface, the rolling surface, the state of the mating surface, the wear of the cage, the increase of the bearing clearance, and the damage and abnormality that are irrelevant in 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 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, and ribs. The higher the importance of bearings, the more careful inspection is required.

Second, the lubrication of the bearing

The purpose of bearing lubrication:

The purpose of lubrication of rolling bearings is to reduce internal friction and wear of the bearings, to prevent sticking, and the lubricating effect is as follows.
(1) Reduce friction and wear.
In the mutual contact portion of the ferrule, the rolling element and the retainer constituting the bearing, metal contact is prevented, and friction and wear are reduced.
(2) Extend the fatigue life.
The rolling fatigue life of the bearing is prolonged when the rolling contact surface is well lubricated during rotation. Conversely, if the oil viscosity is low and the thickness of the lubricating oil film is not good, it is shortened.
(3) Discharge friction heat and cool.
The circulation oil supply method or the like can be used to discharge heat generated by friction or heat from the outside to cool. Prevent the bearing from overheating and prevent the lubricant from aging itself.
(4) Others: There are also effects of preventing foreign matter from entering the inside of the bearing or preventing rust and corrosion.

Lubrication method:

The lubrication method of the bearing 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 and comparing the advantages and disadvantages of grease lubrication and oil lubrication.

Third, the installation of the bearing:
Whether the bearing is installed correctly affects accuracy, life and performance. Therefore, the design and assembly department should fully study the installation of the bearing. I hope to install according to the operating standards. The items of the job standard are usually as follows:
(1) cleaning the bearing and bearing related components;
(2) Check the size and finishing of the connected components;
(3) installation;
(4) Inspection after installing the bearing;
(5) Supply lubricant.

Generally grease is lubricated, not cleaned, and directly filled with grease. Lubricating oil is not necessary for cleaning. However, for instruments or high-speed bearings, it should be cleaned with clean oil to remove the rust inhibitor applied to the bearing. The bearing with the rust preventive removed is easy to rust, so it cannot be placed. Furthermore, bearings that have been sealed with grease are used without cleaning.

The mounting method of the bearing varies depending on the bearing structure, fit, and conditions. Generally, since the shaft is mostly rotated, the inner ring needs an interference fit. Cylindrical bore bearings, press with multiple presses, or use hot charging methods. For taper holes, mount directly on the taper shaft or with a sleeve.

When installed in the outer casing, the general clearance fits a lot, and the outer ring has an interference amount, which is usually pressed by a press or a cold shrink fit method after cooling. When dry ice is used as the coolant and the shrinkage is installed, the moisture in the air will condense on the surface of the bearing. Therefore, appropriate rust prevention measures are required.
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Analysis of different fault life of linear bearings

Fatigue life: The material of the main moving parts of the linear bearing reaches the limit, resulting in the accumulated time before the linear bearing fails.


Rated dynamic load: The load that a linear bearing can withstand when the service life is 10,000 rpm.


Equivalent dynamic load: The assumed load in which the actual load of the linear bearing is converted in accordance with the operating conditions for determining the dynamic load.


Wear life: The cumulative working time of the linear bearing before it reaches the specified limit due to normal wear. At today's linear bearing industry level, wear life > fatigue life should be used, but in fact traction motors are just the opposite.


Fault life: The cumulative working time before the linear bearing fails and the working capacity is lost.


Service life: It is the above three life-finding formulas. In theory, it refers to the fatigue life of linear bearings. In normal use conditions, it shows the wear life of linear bearings. When the conditions are abnormal and there are no defects in manufacturing, it represents the fault life. .
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