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NSK Bearing Basics
Posted byվԱ | Published2011-9-8 | Reading28186
Bearing Basics
Generally within the inner bearings, outer ring, rolling elements and cage composed of four parts. For sealed bearings, including lubricants and seals of two parts. Bearing in work, able to withstand the radial load or axial load, at a certain speed of rotation, will produce radial or axial runout. According to the working condition of bearings to choose different types of bearings, in order to better play to the function of bearing and prolong bearing life.
Bearing life
The performance of rolling bearings, for different purposes, shall be required to maintain its performance during the period. Even if the correct bearing for a particular purpose will, over time, noise, vibration, increased wear and tear caused by decreased accuracy, grease aging strip rolling surface fatigue can not be used. As of this bearing can not be used in a broad sense of the bearing life period. Each is called: Noise life, wear life, grease life, rolling fatigue life and so on.
Why bearing damage?
Only part of the bearing damage in practical applications. Most of the bearing application over the life of a machine or device itself. Bearing damage many reasons - beyond the original estimate of the load, non-tight seal or too small with the result of bearing clearance and so on. Any one factor has its unique form of damage and signs of damage will be a special place. Therefore, to view damage to the bearings, in most cases, the possible factors can be found, and based on these findings, the measures taken to prevent recurrence.
Generally speaking, one-third of the fatigue damage based on the reasons for bearing failure, and one third because of poor lubrication, and other contaminants from entering the bearing is one-third of improper handling or installation. Bearing damage in the form are associated with different industries. For example, the electronics industry on the indoor temperature is higher, which requires fans to be running round the clock, fan bearing most of the damage caused due to fatigue; and pulp and paper industry is mostly due to pollution caused by poor lubrication or bearing damage.
Why bearing failure in advance?
Improper assembly
A variety of bearing failure in advance of 16% is due to improper assembly and assembly tools will not be used due. Some devices require the use of mechanical, hydraulic or heat methods to be correct and effective installation and removal. Use of special tools and techniques of professional assembly, is to achieve maximum machine run time extension of another solution.
Improper lubrication
Although you can install a variety of "maintenance free" sealed bearings, but the early failure of the bearing grease is still 36% is due to the technical application of incorrect and improper use. Any improper lubrication of bearings will inevitably fail in advance of normal life. Since bearings are usually the most difficult mechanical handling equipment, parts, lubrication problems will occur less frequently.
Bearings are precision components, bearings and grease pollution if you can not operate effectively. In addition, the maintenance has been marked with grease sealed bearings all use only a small portion of the bearing, all in the early failure of a bearing at least 14% were due to pollution caused.
If the machine is overloaded, use or improper maintenance, bearings will be affected, resulting in early failure of a bearing 34% is due to fatigue caused. The bearing stress in the maintenance of inappropriate or excessive will be issued when "early warning", so equipment operators or maintenance staff to observe the performance of the bearing operating anomalies.
Why bearings need lubrication?
Theoretically, a well-oiled, in an ideal working conditions, bearing life should be to never, of course, is simply not possible, but if correctly lubricated bearings, the bearings will reach the longest working life. Rolling bearing lubrication to reduce internal friction and wear, to prevent the burning stick, and its lubricating effect as follows:
1, to reduce friction and wear.
   Constitute the bearing rings, rolling contact with each other and the retainer part of the formation of a layer of film, even in the case of heavy load, but also to prevent the metal contact, reducing friction, wear and tear.
2, extending fatigue life.
   Fatigue life of rolling bearings, rolling contact surfaces in the rotation good lubrication, the extension; the other hand, the end of the oil viscosity lubricant film thickness is not good, is shortened.
3, the discharge of frictional heat, cool.
   Cycle oil to the oil law to discharge the heat generated by friction or heat coming from the external cooling. Prevent bearing overheating and prevent its aging oil.
4, other.
   Inside the bearing to prevent foreign invasion, or to prevent rust, corrosion effects.
The use of bearings
Bearings are precision components, their use must also be appropriate caution. Regardless of how high-performance bearings, if used improperly, it will not get the expected performance. Note the use of the bearing is as follows:
1 to maintain bearing and the surrounding clean.
Even the eyes can not see the small dust, will bring bad influence to the bearings.
2, the careful use.
Bearings were in use will have a strong impact scars and indentations, a cause of the accident.
3, using the appropriate operational tools.
Instead of the existing tools to prevent, you must use the right tools.
4, bearing in mind the rust.
Operation will be rusty hands sweat reason, pay attention to the hand with a clean operation, it is best to wear gloves as much as possible.
Bearing Installation
Bearing is properly installed, affecting the accuracy, longevity, performance. Therefore the design and assembly departments for the installation of bearings to be adequately studied. Want to be installed in accordance with operating standards. Standard project work is usually as follows:
1, cleaning bearings and related components
2, Check the size of connected components and precision machining conditions
3, the installation
4, after the check bearing installed
5, the supply of lubricant
Recommended the use of bearings before installation package had just opened, so as not to rust.
Bearings is due to bearing structure, with, conditions vary, the general, as more axis rotation, so the inner ring interference fit requires. Cylindrical bore bearing, multi-press pressed into hot equipment or methods. Cone of the occasion, directly installed in the taper shaft or sleeve installation. Most types of bearings are generally installed using the following method:
1, with the press indentation method
2, the hot charging method
3, the cooling method
There is also the use of advanced electromagnetic induction heating device for installation within a short time without fire, uniform heating oil, cleaner, more efficient installation. Please refer to the Division I bearing heater
Bearing removal
Bearing the demolition, is regular maintenance, replacement bearings were. After demolition, such as the use or need to continue to check the bearings of the state, the removal and installation should be as carefully. Care not to damage bearings and various parts, especially the demolition of the interference fit bearing operation is difficult, it is necessary to note. Removing bearings can be used presses, drawing fixtures, extrusion screws, induction heating equipment, oil and other several methods.
Note the bearing in operation
Check the status of the operation of the machine and prepare a thorough inspection program has become increasingly important. Among them, bearing the focus of attention because it is the most important of all rotating machinery parts. Irregular use of hearing to identify the operation is a very common method, the bearings are in good operating condition if it emits a low hum of voices; if a sharp hissing sound, audio and other irregular creaking sound, usually Bearing that in poor operating conditions. How to listen? Old method: Use a stick or screwdriver up against the bearing housing on the other end of the stick to the ear; advanced methods: the use of advanced equipment such as electronic monitoring equipment status, pre-diagnosis of the functioning of the bearing.
If the bearing temperature of 125 over the long-term operation, will reduce bearing life, high temperature bearings often in unusual circumstances that caused the high temperature of reasons: lack of lubrication or over lubrication, lubricants containing impurities, the load is too large, bearing damage, lack of space, and generate high friction oil seal and so on. Therefore, bearing temperature detection is necessary, whether it is important to measure the bearing itself or other parts. The old way is to touch the sense of bearing housing temperature, can now help of temperature detectors, which can accurately measure the temperature of the bearing and displayed so that effective conservation measures.
If you get a good bearing lubrication and the right debris and moisture barrier that seals should not be worn. However, the best bearing box in the open to visual inspection and periodic checks bearing oil seal. Check the oil seal at the situation near the bearings to ensure they are adequate to prevent hot liquids or corrosive liquids or gases into bearing along the axis. Labyrinth seal protection ring and grease should be applied to ensure the greatest protective effect, seal Ruoyi wear should be replaced soon.
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