A brief analysis on low friction, high speed and precision of bearings
Bearings are indispensable and key basic components in modern industry. They are known as the "heart" of mechanical equipment. Their carrying capacity will directly affect the technical level of the equipment and are an important criterion for measuring a country's technological and industrial strength. However, with the development and evolution of downstream industries, traditional rolling bearings have become increasingly "overburdened." Large-scale and high-speed equipment has become a trend. More stringent operating conditions and high reliability requirements have posed new challenges to bearing technology. After more than 40 years of development, my country's bearing industry has made great progress in bearing products and manufacturing levels, and has considerable scale and development foundation. With the advancement and
development of technology, higher and higher requirements have been placed on the performance and requirements of bearings. This article mainly discusses the development trends of bearing technology from the aspects of low friction and high speed and precision.
Tribology technology is the core technology of bearings, and the significant technical feature of the new generation of bearings is friction reduction design. Compared with sliding bearings, rolling bearings themselves are "anti-friction bearings". The challenge of the new generation of anti-friction design is to significantly reduce the already extremely low friction torque, the maximum reduction can even reach 80%. In new energy vehicle applications, low friction bearings are required to reduce energy consumption losses; in aerospace application requirements, bearings are required to have low-temperature friction resistance. Bearing friction is not constant. It depends on certain friction phenomena that occur in the lubricating film between the rolling elements, raceways and cages. The technical indicators that affect the low friction of bearings mainly include width-to-diameter ratio, bearing clearance, bearing wall thickness, and special design suitable for extreme (extreme) working conditions.
The high speed and low speed of the bearing are not measured by the rotation speed of the bearing itself, but by its linear speed. Generally, bearings with a linear speed of 60 meters per second can be considered high-speed bearings. High-speed bearings usually have smoother surfaces and a very small distance between the inner and outer rings, so the requirements for bearing accuracy are higher. The main factors that affect the bearing speed include bearing type, size, load, lubrication method, cage material and type, bearing load, preload force, driving method, bearing clearance size and bearing combination .
1) Bearing type and size: Different types of bearings are different in structure and material. The larger the size, the greater the moment of inertia, which will affect the speed of the bearing. 2) Load: The greater the load the bearing bears, the greater the frictional resistance, which affects the speed. 3) Lubrication method: Appropriate lubrication method can reduce friction and wear, increase the speed of the bearing. 4) The material and type of cage: will also affect the speed of the bearing. 5) Bearing load: The limit speed of a rolling bearing is the maximum speed reached under a certain load and lubrication conditions, and the bearing type, size, direction, lubrication method, clearance, cage structure, Cooling conditions, etc. have a lot to do with it.
6) Preload force: Excessive preload force will cause the contact stress between the rolling elements and the raceway surface to increase, and the heat generation will increase, which will further increase the preload force inside the bearing, making the bearing more durable. It is easy to cause wear and reduce the limit speed. 7) Driving mode: The different spindle driving modes will affect the limit speed of the bearing. For example, when driven by an electric spindle, if the outer cylinder is used for cooling at the same time, may cause the temperature difference between the inner and outer rings of the bearing to become larger, and increase the internal load. Resulting in a reduction in the limit speed. 8) The size of bearing clearance: The size of clearance has an important impact on the operating performance and life of the bearing. Appropriate clearance can improve the bearing capacity and limit speed of the bearing. 9) Bearing combination: By supplying a large amount of oil to quickly take away the heat generated by the bearing, the limit speed can be increased.