Airlines launched machine bearing skid reason in detail

Realized China bearing network, general machinery used in rolling bearing because of the low speed, and there has always been load act on it, rarely present skid phenomenon. But the aviation gas turbine main bearing is easy to slip, this is because: ( 1) High speed. Under the effect of high speed, the roller under the effect of large centrifugal force has a tendency to be out of the inner ring raceway contact; ( 2) The load is small. Airlines launched machine rotor are doing lighter, make effect on bearing radial load is small, and a maneuvering flight plane under certain conditions, when they make effect on the bearing load of smaller, and presents the zero load, as well as the rotor imbalance force under certain conditions would offset some effect on the bearing radial load, form the light load or no load bearing. The elements of these two aspects will make the drag power produced by friction is small, that is zero, so, will inevitably provoke bearing sliding, present smooth ceng damage. About the ball bearing, since it also receive axial load, so ordinary is not easy to skid. Airlines launched machine bearing some measures to avoid skid with drag power increased measures to prevent sliding bearing ceng reduce bearing clearance, the roller under the action of centrifugal force can still insist on contact with the inner ring groove. For example CFM56 launched machine rolling bearing high pressure turbine rod bearing ( Intermediate bearing) With the small clearance that is negative clearance to reduce slippage; And as WJ6 launched machine roll bar before the compressor bearings in the long run appear serious slide after injury, the bearing clearance by 0. 070-0. 095 mm decrease to zero. 045-0. 065 mm, eliminate the phenomena of ceng. But, using the measures for decreasing the clearance will lead to other serious problems, and therefore should be treated with caution, especially on hot side bearings in a machine, should be more careful. Initiated in the early days of aviation gas turbine machine, to adhere to the frame of equilibrium solution, how will the persistence of the main bearing positioning from outer ring, but the design is easy to cause the bearing to present slip damage. This is because when stick to locate in the outer ring, exist in between outer ring and adhere to the frame of oil film under the action of viscous block rolling stick stick to frame for normal motion triggered skid. As will stick to locate in the inner ring, exists in the inner ring and adhere to the frame of the oil film between the roller insist on frame under the action of viscosity will assembly a drag power have made its normal movement. In this way, will be scheduled in the persistence of the outer ring into position on the inner ring, not only reduced the resistance, but also increase the power, will obviously reduce sliding ceng damage, of course this progress must also adhere to frame the machining precision of the equilibrium degree of progress. Assembly, impose an additional on bearing radial or axial load, namely on bearing 'preloading', make the bearing work, has been, and between the outer ring raceway and roller has the effect that load, not light load or no load, to increase the drag force. On bearing preloading method: USES the non-circular bearing and axial spring on bearing preloading and roll adopts the hollow rod and adjust the fuel injection direction of bearing, etc. The bearing outer ring made of circular cylindrical, and casing unit bearing seat hole still make it round. Commonly used non-circular bearing with elliptical bearing outer ring and bearing outer ring of 3 valve type. Press the elliptical bearing, for example, into the bearing hole, the axis of the ellipse ( Outside the ring protruding parts) I. e. , one of the roller to here additive loads, such as the long axis in a level position as shown in figure 3, a few of the roller in the position of in degree between the inner and outer ring and always adhere to the contact load and effect to a certain extent, therefore, in addition to the lower roller by gravity load, the effect of several 90 ° around the roll bar, also the load by a certain amount of additive, to accept the load roller number increased to about 60% of the total number of roller, can produce certain power, restrain sliding bearing. 'Skid' is used to indicate the rolling bearing can be serious level of sliding and sliding when adhere to the practice, the rotational speed is equal to the frame theory of bearing no skid and the skid degrees to zero; Just keep practice speed is lower than the theoretical speed, bearing the skid, when stick to practice speed is zero, skid degree is 100%. Common with determination to stick to the practical speed to the plane bearing sliding degrees are obtained. Angelo, a firm in machine, to carry out the RB211 by using radioactive isotopic never detecting sliding bearing. On the rack fixed a small with cobalt or iridium ( Co 60,Ir 192) Silk source, application of the inverse square law ( That reached a certain point of radioactivity is from source to point interval square) Adhere to the principle of measuring charge work speed, and bearing can present skid, and can calculate the skid. Also can be used for cutting the magnetic field lines for measuring stick to the principle of the aircraft speed. Avoid axial load acting on the ball bearing to as mentioned above, the RB211 fan rotor bearing thrust bearing as a intermediary, because of the fan rotor in the work can present axial force direction changes, thus in use ( In April, 1972) Less than half a year, then present the ball bearing slide ceng damage. Then take the foregoing will adhere to the orientation of outer to the inner ring measures, deal with the problem on a certain level, but due to the axial load commutation problem without treatment, so for a long time, in all sorts of retrofit RB211 ( 524 b, 524 c, 524 d4 and 524 d4upgrade, etc. ) , or occasional rendering the bearing slide ceng damage. Therefore, at the end of the RB211 retrofit RB211524G/H ( Use the year 1989) , the diameter of the unloading chamber sealing YanHuan place by 556. 20 mm increase for 731. 52 mm, eliminate the rotor axial load in the reversing. Basically dealing with the slippage of the bearing. Carried out by RB211 524 g/H derivative trent launched machine, in addition to using the balance of the large diameter cavity closure YanHuan outside, still in the low pressure turbine shaft back-end install on rotor preloading springs and small bearings, basically dealing with sliding bearing. Introduction: what is a smooth smooth bearing grease bearing grease better choice