Oil-free sliding bearing (English name: Oilless Sliding bearing) refers to a special bearing. The novel lubricated bearing, which combines the characteristics of metal bearings and the characteristics of oil-free lubricating bearings, is loaded by a metal substrate, and the specially formulated solid lubricating material acts as a lubricant. It has the characteristics of high bearing capacity, impact resistance, high temperature resistance and strong self-lubricating ability. It is especially suitable for heavy load, low speed, reciprocating or swinging, etc., which is difficult to lubricate and form oil film. It is also not afraid of water and other acid etching. And scouring. The material has a metal material, etc., and is characterized by a simple structure and convenient manufacture. The material of the bearing bush and bearing bushing is collectively referred to as a plain bearing material. Sliding bearing applications are generally used under low-speed and heavy-duty conditions, or where it is difficult to maintain and fill lubricants.
The oil-free sliding bearing can be self-lubricated by design, and it works smoothly, reliably and without noise. Under liquid lubrication conditions, the sliding surface is separated by the lubricating oil without direct contact, and the friction loss and surface wear can be greatly reduced, and the oil film also has a certain vibration absorbing capability. However, the starting friction resistance is large. The part of the shaft that is supported by the bearing is called the shaft diameter, and the part that matches the shaft diameter is called the bearing bush. The layer of friction reducing material cast on its inner surface in order to improve the frictional properties of the surface of the bearing pad is referred to as a bearing lining.
Bearings are components that fix and reduce the coefficient of friction of the load during mechanical transmission. Its main function is to support the mechanical rotating body to reduce the mechanical load friction coefficient of the equipment during the transmission process. According to the friction properties of moving components, bearings can be divided into two types: rolling bearings and sliding bearings.
In order to ensure the smooth and reliable operation of the bearings, most of the bearings are lubricated for lubrication, in order to reduce the internal friction and wear of the bearings, to prevent sticking: to prolong the fatigue life of the bearings; to discharge frictional heat, or heat from the outside. At the same time, the oil film also has a certain vibration absorption capacity. However, the biggest disadvantage of adding lubricating oil is that it requires good sealing performance, otherwise it will cause leakage, and some have special requirements. The equipment does not allow leakage of lubricating oil. Therefore, people use other lubricating materials instead of lubricating oil to invent. Oil-free bearings make it not only have the advantages of lubricating bearings, but also prevent environmental pollution caused by leakage.
classification
Oil-free bearings mainly include gas lubricated bearings, composite lubricated bearings, and water lubricated bearings.
First, gas lubrication bearings:
Gas lubricated bearings are plain bearings that use gas as a lubricant. The most commonly used gas lubricant is air, and nitrogen, argon, hydrogen, helium or carbon dioxide may also be used as needed. Gas-lubricated bearings form the same mechanism as liquid-lubricated bearings. Gas lubricated bearings utilize gas transportability, diffusivity, viscosity and thermal conductivity, adsorption and compressibility. Under the action of fluid dynamic pressure effect, static pressure effect and extrusion effect, a complete gas film is formed between the friction pairs, which has the functions of supporting load and reducing friction.
Gas lubricated bearings are generally classified into three types: gas dynamic pressure bearings, gas static pressure bearings and gas extrusion bearings. The lubrication state of the actual bearing often exists in the form of dynamic and static pressure, dynamic, extrusion, static, extrusion and dynamic, static and extrusion lubrication. Gas-lubricated bearings form the same mechanism as liquid-lubricated bearings.
Second, composite lubrication bearings
Due to the requirements of special production processes, some key equipment of industrial and mining enterprises operate under extremely harsh conditions. Due to the heavy equipment and high ambient temperature, the dust is large or the air contains acidic corrosive gases. There are many problems in the lubrication of the equipment, and the friction and wear are serious. At present, most of the oil and grease lubrication are still used. In fact, these industrial and mining conditions have exceeded the range of oil and grease lubrication. Very easy to bite or bite the bearing and other friction pairs. Causes severe wear and damage of parts, often causing equipment to be out of service.
The composite material used in composite lubricated bearings is a new type of extreme pressure resistant solid lubricant consisting of a metal substrate and a solid lubricant paste embedded in the holes or slots of the substrate. The metal substrate takes up most of the load during the rubbing process. After friction, the solid lubricant in the hole or the groove is transferred or reversely transferred to the friction surface, and a solid transfer film which is well lubricated, firmly adhered and uniformly covered is formed on the friction surface, and friction and wear are greatly reduced. As the friction progresses, the embedded solid lubricant is continuously supplied to the friction surface, ensuring good lubrication of the friction pair during long-term operation.
Third, water lubricated bearings
Since the oil resource crisis in the 1970s and the emphasis on environmental protection in recent years, hydraulic transmission technology is facing severe challenges, and water-lubricated bearings are gradually being promoted and applied. Water-lubricated bearings use water as a lubricant and working medium, which not only saves a lot of oil, but also avoids the environmental pollution of traditional bearings with oil as a lubricating medium. At the same time, water has the advantages of no pollution, wide source, safety and flame retardancy, and is an ideal lubricating medium. Moreover, it can also reduce the key problems of friction, wear, vibration, noise, and non-functional consumption of the friction pair. Therefore, the research of water-lubricated bearings has important theoretical research and application value for improving mechanical efficiency and protecting the environment, and has become a hot spot of concern to all countries. [2]
material
The materials for oil-free sliding bearings are:
(1) Metal materials, such as high-strength brass, tin bronze inlaid graphite bearings, etc.
(2) porous metal materials (powder metallurgical materials);
(3) Non-metallic materials (nylon, polytetrafluoroethylene).
(4) Non-metallic oil-free sliding bearings
application
SF-2 Boundary Lubrication Bearing: Acidic polymethyl aldehyde with high wear resistance. The bearing surface has a regular arrangement with oil storage pits. It must be coated with grease when it is assembled. It is especially suitable for high load and low speed. Rotating motion, rocking motion, and often under load, opening and closing, which is not easy to form fluid lubrication. Under boundary lubrication conditions, it can be used for a long time without oiling and maintenance, and the process can be extended by the oiling process. Currently applicable to metallurgical machinery, mining machinery, hydraulic machinery, auto parts, construction machinery, agricultural machinery, etc.
Oil-free self-lubricating bearing: This product is made of steel plate as the base, the middle layer is sintered with spherical bronze powder, and the surface layer is rolled with a mixture of polytetrafluoroethylene [ptfe] and lead. It has the characteristics of small friction coefficient, wear resistance and corrosion resistance, oil-free self-lubrication and long service life. It can reduce cost, reduce noise and prevent sticking and slipping. It is widely used in various mechanical sliding parts such as printing machines, textile machines, hydraulic pallet trucks, tobacco machines, medical machinery, fitness equipment, micro-motors, automobiles, motorcycles, etc.
Metal-based inlaid solid self-lubricating bearing: It is a novel lubricated bearing that combines the characteristics of metal bearing and the characteristics of self-lubricating bearing. The metal matrix bears the load, and the specially formulated solid lubricating material acts as a lubrication. It has the characteristics of high bearing capacity, impact resistance, high temperature resistance and strong self-lubricating ability. Traditional oil-impregnated bearings: Due to the advantages of low hum and self-lubrication, oil-impregnated bearings have become the new darling of computer CPU fan bearings, and the market demand is large. In addition, with the increasing demand for voice, oil-bearing bearings are The application of everyday household appliances is also expanding.
Application field
1. Sleeve sleeves and pin sleeves for joint parts of construction machinery (excavators, bulldozers, loaders).
2. Heavy duty balance shaft bushing.
3, car, motorcycle shock absorber bushing.
4. Hydraulic industry, hydraulic gear pump bushings, cylinders, cylinder liners, etc.
5, injection molding machine, vulcanizing machine.
6, mold industry, plastic mold, automotive mold guide sleeve
7. Hydraulic machinery turbine turbine.
8, forging industry, punching and so on.
9. Metallurgical industry.