The origin of bearing development
The early form of linear motion bearings was to place a row of wooden poles under a row of skid plates. Modern linear motion bearings use the same working principle, but sometimes use balls instead of rollers. Z's simple rotary bearing is a bushing bearing, which is just a bush sandwiched between the wheel and the axle. This design was subsequently replaced by rolling bearings, which replaced the original bushings with a lot of cylindrical rollers, each of which was like a separate wheel.
An early example of a ball bearing was discovered on an ancient Roman ship built in 40 BC in Lake Nami, Italy: a wooden ball bearing was used to support a rotating tabletop. It is said that Leonardo da Vinci once described a ball bearing around 1500. Among the various immature factors of ball bearings, there is a very important point that collisions between the balls will cause additional friction. But this phenomenon can be prevented by putting the balls in small cages one by one. In the 17th century, Galileo made an early description of the "cage ball" ball bearing. At the end of the seventeenth century, British C. Wallo designed and manufactured ball bearings, and installed them on mail trucks for trial use, and British P. Worth obtained a patent for ball bearings. The rolling bearing with cage that Z put into practical use early was invented by watchmaker John Harrison in 1760 to make the H3 chronograph. At the end of the eighteenth century, German H.R. Hertz published a paper on the contact stress of ball bearings. On the basis of Hertz's achievements, R. Stribeck of Germany, A. Palmgren of Sweden and others have conducted a large number of experiments, and have made contributions to the development of rolling bearing design theory and fatigue life calculation. Subsequently, Russia’s N.P. Petrov applied Newton’s law of viscosity to calculate bearing friction. The first patent on the ball channel was obtained by Philip Vaughan of Carmarthen in 1794.
Features of bearing steel:
1. Contact fatigue strength
Under the action of periodic load, the bearing is prone to fatigue damage when contacting the surface, that is, cracks and peeling appear, which is an important damage situation of the bearing. Therefore, in order to improve the service life of the bearing, the bearing steel must have a high contact fatigue strength.
2. Wear resistance
During the bearing task, not only rolling friction occurs between the ring, rolling element and the cage, but also sliding friction occurs, so that the bearing parts are constantly worn. In order to increase the wear of bearing parts, maintain the accuracy and stability of the bearing, and extend the service life, the bearing steel should have good wear resistance.
3. Hardness
Hardness is one of the important qualities of bearing quality, and it has an indirect influence on contact fatigue strength, wear resistance, and elastic limit. The hardness of bearing steel under operating conditions must reach HRC61~65, which enables the bearing to achieve higher contact fatigue strength and wear resistance.
It is to fix the shaft so that it can only achieve rotation, while controlling its axial and radial movement. The motor cannot work at all without bearings. Because the shaft may move in any direction, and the motor is required to only rotate when it is working. Theoretically speaking, it is impossible to achieve the role of transmission. Not only that, but the bearing will also affect the transmission. In order to reduce this effect, good lubrication must be achieved on the bearings of the high-speed shaft. Some bearings are already lubricated, which are called pre-lubricated bearings. Most bearings must have lubricating oil. When running at high speeds, friction will not only increase energy consumption, but even more frightening is that it is easy to damage the bearings. The idea of turning sliding friction into rolling friction is one-sided, because there is something called a sliding bearing.