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With the progress of bearing manufacturing technology and the increase of users' demand level, the proportion of lubrication to bearing importance and quality index has been greatly increased.
In the process of bearing design, manufacture and application, especially the sealed bearing, grease has become an important part of bearing. Is lubricant used scientifically?
Being reasonable, it will become one of the key factors to determine the life of bearings. When designing and selecting grease, it is usually considered from the following aspects.
2.1 effect of lubricant parameters on bearing
The important parameter of lubrication process is the thickness of lubricating film, and the viscosity of lubricant is an important factor affecting the thickness of lubricating film.
It is enough to exceed the peak value of the surface roughness of the two friction bodies, so as to achieve the separation of the friction pairs. It is generally considered that the thickness of the lubricating film should be more than four times that of the surface roughness.
。 One of the most commonly used methods for determining the viscosity of lubricants is theoretical calculation, the two is the simulation of film thickness, and the three is the empirical examination. Either way, most bearings are lubricated.
Viscosity indices related to lubricant film thickness are all used. If the surface roughness of the bearing can not be reduced, so that the thickness of the lubricating film can not be reduced, the result is lubrication.
The viscosity of grease is much higher than the actual requirement. The increase of viscosity can ensure the thickness of lubricating film, but the shear strength of lubricating grease will also increase, resulting in lubricating grease.
The internal friction intensified, which consumed more energy of the machine. In the mass bearing lubrication problem of low accuracy, because these defects are not very prominent, they are often in daily work.
It has not attracted enough attention.
2.2 effect of lubrication on vibration and noise of bearings
With the upgrading and upgrading of the equipment, the manufacturing accuracy of bearings has been greatly improved. Vibration and noise are the main indexes to measure the quality of bearings.
The oil film is kept well, which can effectively keep vibration and noise in a low state. Vibration and noise are often measured after bearing assembly and bearing.
The use of medium to low vibration and low noise can keep the length of time. Before the bearing reaches service life, the vibration and noise of the bearing will run over the bearing.
There is a fluctuation in the process, and its fluctuation is changed with the change of the lubricant working conditions, so that the lubrication condition is not achieved when the bearing is running.
The vibration and noise of bearing will be correspondingly bad when conditions are met. With the change of bearing operating conditions, such as temperature rise, the vibration and noise of bearings are fully realized when the performance of lubricants is brought into full play.
The sound will obviously decrease, but as the bearing running time is prolonged, the lubrication function of the lubricant will gradually lose, and the vibration and noise of the bearing will rise. generally speaking
The initial vibration and noise of bearing have a great bearing on the accuracy of bearing manufacturing. After a period of running, the effect of lubrication performance on vibration and noise is more significant.
Highlight. The adhesion, viscosity, temperature and wear resistance of lubricants affect the duration of low vibration and noise life.
The magnitude of the vibration and noise of the bearing is not only decided by the precision of the bearing, but also largely influenced by the performance of the bearing grease. As bearings
Manufacturing enterprises should consider comprehensively the factors such as the composition, performance, lubrication mode of bearing grease, the influence degree of lubricant used in bearing working conditions, and so on.
Ensure that the bearing vibration and noise can maintain a good level.
2.3 effect of lubrication on friction and wear of bearings
The main purpose of rolling bearings widely used in mechanical equipment is to reduce friction in rotating parts. With the emergence of new equipment,
There are more and more requirements for reducing friction more effectively, such as low energy consumption household electrical appliances bearings, battery powered power bearings, and portable batteries.
Electric bearings for electric tools. Besides, the effective means to reduce the running friction of bearings are not only the design of bearing rings and rolling materials, but also the size and structure of the rolling bearings.
The performance of slip agent plays a leading role. The friction coefficient of general lubricating grease is about 0.02, and the friction coefficient of lithium grease can be as low as 0.007.
The internal friction of grease itself is also an effective way to reduce friction, and the viscosity of lubricating grease is the main factor affecting internal friction. Friction is usually achieved by continuous high strength.
The wear surface of the bearing will appear when the state is in degree. With the continuous expansion of the wear, the bearing surface will lose fatigue strength and scrap.
Although friction is the cause of wear and tear, the reason for bearing wear is not merely friction, but also the surface of the lubricating oil on the friction pair under the working condition of the bearing.
A layer of multi-layer orientated molecular grating is the boundary film. The cohesive force between the boundary membrane molecules has certain load-carrying capacity. The important factor determining the lubrication state is the edge.
The ability of boundary membrane to resist breakage boundary film strength. The following forms of wear are related to lubrication: because the strength of the lubricant film and boundary film is not enough, it is easy to cause adhesion.
Wear and surface fatigue wear; due to the smaller lubricant film thickness, frictional pairs appear rigid contact, lubricants contain large size abrasive particles and other impurities, and lubricant repels.
It is easy to cause abrasive wear due to low abrasive wear capacity; lubricating oil itself is a chemical substance, which may cause corrosion to metals and cause wear and tear. In summary
In order to reduce or avoid bearings related to lubrication