Factors determining the stability of plain bearings
The function of lubricant is to reduce friction, reducing wear, cooling and vibration absorption, a lubricant liquid solid and gas and semi solid, liquid lubricant called lubricating oil, semi solid, at room temperature in oil paste is grease. Lubricating oil is the main lubricant. The main physical performance index of lubricating oil is viscosity, which indicates the internal friction properties of liquid flow, and the greater the viscosity, the worse its flowability. Another physical property of lubricating oil is oiliness, which represents the adsorption ability of lubricating oil on the metal surface. The greater the oil, the stronger the metal adsorption capacity, the more likely the oil film to form. The selection of lubricating oil should take into account the bearing capacity, journal speed, lubrication mode, surface roughness of sliding bearing, and other factors. The general principles are as follows: 1. in the high speed and light load working conditions, in order to reduce the friction loss of lubricating oil viscosity can be selected;
2. in the working conditions of heavy load or impact load, the big oil, the viscosity of the lubricating oil, the lubricating film forming stable; 3. static or dynamic static pressure sliding bearing lubrication can be selected the oil viscosity is small; the 4. surface roughness or surface without running should choose the lubricating oil with high viscosity. Sliding bearing grease shaft speed less than 1m/s~2m/s can be used to grease, grease is agent with mineral oil, all kinds of thick (such as calcium, sodium, lithium, aluminum and other metal soap) and water to reconcile, grease consistency (penetration), large bearing capacity, but the physical and chemical property is not stable, should not be used in large temperature variation conditions for low speed and heavy load or the swing bearing. Solid lubricants and gas lubricants, solid lubricants are graphite, molybdenum disulfide (MoS2) and PTFE (PTFE) and other varieties. Usually used under heavy loads or under high temperature conditions. A gas lubricant, usually air, used for high speed and lubricating or grease free applications. Method to provide lubrication bearing lubricant is a necessary condition for the formation of the lubricating film, hydrostatic bearing and bearing through the oil pump, the throttle and the bearing oil groove to continuous supply of sliding bearing, the formation of oil film bearing and shaft neck surface makes separate.
