We know that the shaft and the sliding bearing are a pair of friction pairs, which are sliding friction.
The friction will be hot, and the amount of heat generated is proportional to the frictional force and proportional to the speed of the movement; the friction is large, the heat is large, and the speed is much faster.
The frictional force of the sliding bearing is proportional to the positive pressure and the friction coefficient. From the design point of view, the total load is determined. After the bearing diameter and length are determined, the pressure per unit area is also fixed, and these conditions are met during operation. The bearing will not heat up, but the operation will change. When the total load increases, the actual contact arc length, and the actual contact length change, the pressure per unit area will increase.
This is a problem. In fact, the friction coefficient increases as the pressure per unit area increases. Once the friction coefficient increases, the friction heat increases. Once the heat is generated, the frictional heat is greater than the amount of heat that can be dissipated. When broken, the bearing will heat up.
In fact, when the pressure per unit area of the sliding bearing increases, the friction coefficient increases rapidly. See the following table for details.
When the pressure of the sliding bearing increases, the friction coefficient increases, because the friction work is equal to the product of the friction coefficient, the positive pressure and the moving speed. When the contact is poor, the contact area decreases and the pressure increases; the total load increases when the equipment vibrates. Large, the pressure will increase, then the friction coefficient will increase, the heat generation will increase, and the sliding bearing must heat up.
Therefore, the contact accuracy of the sliding bearing is reduced under any circumstances, and the load increase under any circumstances will cause the local pressure of the sliding bearing to increase, thereby increasing the friction coefficient and causing the bearing to heat up.
Sliding bearing
In order to avoid the inflexibility of the spherical tile, the friction between the shaft and the end of the tile is caused, and the opening is made large. Although the problem is solved to some extent, in a certain sense, the bearing unit is actually increased. The force on the area will shorten the bearing life, and the second will reduce the bearing's ability to resist the risk. When the wind blows the grass, the bearing will heat up, which is not conducive to stable operation.
In order to improve the flexibility of the sliding bearing spherical tile, the contact area between the spherical tile and the tile seat is reduced very small, especially the grooved spherical tile in the middle, only the two sides of the groove are rarely partially contacted, and the friction will be It will increase greatly, which is not conducive to the activities of spherical tiles.
Although the huge pressure does not cause crushing, there is always a press in the local high point. This is like rooting on both sides of the bridge, which increases the stability of the spherical tile. Therefore, in the equipment management and maintenance, it is better to meet the design requirements as much as possible. For some parts with low processing precision, the method should be compensated by manual methods, which has made it meet the design requirements.
The friction coefficient of the sliding bearing is not only related to the pressure, but also related to the speed of the movement. The following is the relationship between the speed and the friction coefficient.
When the sliding bearing equipment is started, the friction coefficient is very large. After the operation, the friction coefficient is reduced, but the change is relatively small within a certain interval, and the magnitude of the change has a great influence on the friction coefficient with respect to the pressure, so the cement is in the kiln. When using fever, the method of lowering the speed of the kiln is often used. Although it has an effect, most of them cannot change the fate of fever. This is the reason.
The sliding bearing works well before stopping, but the tile is hot when it is turned on, or even burnt locally. In fact, it is caused by large friction at startup. At this time, not only the friction is large, but the lubrication condition also fails to meet the requirements, especially the static pressure. Boot device.
On the other hand, if the brake is different, the friction coefficient is from small to large, saying that the high-speed operation of the equipment is difficult to stop, and the sliding bearing is also a brake. It is difficult to explain the high-speed train by the inertial principle. Braking, in fact, the effect of the friction coefficient is also there, at least to extend the parking time.
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