The oil film bearing in rolling mill - bearing lubrication knowledge

by:Waxing     2020-05-30
1 working principle of the oil film bearing in rolling mill oil film bearing is a kind of lubricating oil as lubricating medium radial sliding bearing, its working principle is: in the process of rolling, due to the effect of rolling force, force the roller shaft, oil film bearing center and the center of the shaft neck produce eccentric, makes the oil film bearing clearance between shaft neck and formed the two areas, one is called divergence area ( Direction of rotation clearance increases gradually along the axis neck) And the other one is called convergence zone ( Along the shaft neck rotation direction decreases) 。 When the rotating shaft neck has a viscosity of lubricating oil from divergence to convergence area, along the shaft neck rotation bearing clearance from large to small, form a kind of oil wedge, the lubricating oil pressure. The oil film pressure along the rolling direction of each point in the resultant force is the bearing capacity of the oil film bearing. When rolling force is greater than the bearing capacity, the journal center and the increase of eccentricity between the oil film bearing center. In the convergent zone along the axial bearing clearance steepening neck rotation direction, the minimum oil film thickness decreases, the pressure inside the oil film and bearing capacity, and rolling force balance, journal center no longer offset, the oil film bearing and shaft neck completely separated by a lubricating oil in theory formed the whole fluid lubrication. From the working principle of the oil film bearing can know the oil film bearing is one of the most important parameters in the system of minimum oil film thickness. If the minimum oil film thickness value is too small, and the metal impurity particles in the lubricating oil is too large, the shape of metal particles size on the numerical value is greater than the minimum oil film thickness, the metal particles as lubricating oil through the minimum oil film thickness, like metal contact, serious when will burn. In addition if the minimum oil film thickness value is too small, when there is a pile of the accidents such as steel, it is easy to cause journal and the oil film bearing metal contact and cause tile burning. With the size of the minimum oil film thickness value of oil film bearing structure size and material, the related parts machining precision and installation accuracy of oil film bearing system, lubricating oil and the size of the rolling force and so on, As shown in figure 2-3 1) 。 Thus can satisfy the bearing pressure at maximum range, impact resistance, change speed and the precision of rolling and the service life of the structure size and requirements. The rolling pressure, rolling speed, bearing clearance, and lubricant viscosity match four elements form a continuous stable bearing oil film, liquid dynamic pressure lubrication, in order to meet the friction and lubrication of the rolling mill under different running condition. So the oil film bearing lubrication, often in the following three forms: ( 1) When starting or stopping, despite lubricating oil between shaft and bearing, but due to the movement speed is equal to zero or near zero, hydrodynamic pressure lubrication or has not been formed gradually disappear, shaft and bearing will be in direct contact, at this point in the medium lubrication even half dry friction condition. ( 2) Due to excessive vibration or water or oil supply is insufficient or there is a problem of oil is likely to produce mixed lubrication. ( 3) Mill functioning smoothly, fluid lubrication. Therefore, the oil film bearing lubrication is characterized by the above three conditions exist alternately mixed lubrication. 2 of the oil film bearing in rolling mill characteristics of lubricating oil in order to adapt to high speed and overloaded, automation, large-scale iron and steel enterprise and the need of high yield, solves the oil film bearing in rolling mill lubrication requirements and meet the increasingly harsh working conditions of the lubricating oil used in the oil film bearing in rolling mill have higher requirements. The lubrication characteristics of oil film bearing in rolling mill, decided the lubricant must meet the performance requirements, can guarantee the normal operation of rolling mill and continuous production. The performance of lubricating oil, therefore, need to have: ( 1) Excellent viscosity-temperature performance ( High viscosity index) , when the bearing temperature fluctuations can still achieve the lubrication part of the normal lubrication. ( 2) Superior demulsification performance ( Which can be divided into water based) , in the long-term use can quickly separate oil moisture. ( 3) Good anti-wear and extreme pressure properties, oil mixed with a small amount of water during operation, still can form the oil film to keep overloading and anti-wear properties. ( 4) Good antiwear, antirust and antifoam performance, prevent lubrication system from corrosion, blocking the oil-way, causing wear and fuel supply is insufficient. ( 5) Good oxidation stability, cleaning and filterability, smooth oil lubrication system, insure the normal lubrication.
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