Aircraft engine bearing skid ceng contrast figure and the reason and prevention measures

Skid ceng injury is a kind of common aircraft engine bearing fault, also often happens on ball bearings, bearing sliding ceng injury refers to the subtle wear a special form, due to the high speed light load, bearing, rolling body/raceway contact surface caused by the strong sliding when rotating. Below the bearing network ( Hereinafter referred to as:) To give you make the aircraft engine bearing skid ceng wounded contrast figure and bearing ceng causes and measures in detail. Hurt, aircraft engine bearing sliding ceng contrast figure: figure 1 serving not ceng wounded bearing, macro figure 2 ceng bearing, macro is above 1 serving not ceng wounded bearing, macro and figure 2 ceng bearing, macro; Figure 1 no star in the outer ring surface spalling and deformation, with minor scratches, cage guide surface contact with the roller is part of the sag, the inner ring raceway and roller surface is bright and clean, no abnormal wear and tear. No obvious spalling and figure 2 in the outer surface and deformation ( Figure 2 a) ； Cage guide surface with minor scratches, the contact surface with roller also appears cave ( Figure 2 b) It could be the result of the high speed; Inner ring raceway visible color difference obvious ceng injury parts and injury area uneven, although the circumferential distribution, accounts for about a third of the inner ring raceway area, and to guard one side ( Figure 2 c) ； Cylindrical roller appear obvious brown with the whole week, close to the roller end face ( Figure 2 d) 。 Measuring the 30 roller bearing, the width of the ribbon is 2. 9 mm, but with the inner ring raceway of the injury is not corresponding to the area size. Roller ribbon formation may have originated from the local temperature on the high side, attached to the ceng oxidation injury bearing oil film on the surface of the roller, the beige product oxide film deposition. Visible, ceng wounded bearing and service not bearing significant differences in the macroscopic and microscopic morphology, ceng injury bearing inner ring damage surface spalling pit of thick cloth, roller ribbon with a whole week, and badly worn. Ceng injury roller bearing inner ring and the metallographic structure of the martensite + retained austenite + - Primary carbides + secondary carbides, and burn wound surface layer. Ceng injury bearing inner ring and roller contour integral change significantly, has a tendency to wear. The main reason for the second, bearing skid ceng injury: bearing skid ceng injury performance characteristics are spark to mark the end, as shown in figure 3, is a kind of typical bearing ring skid rub marks. Roller bearing slip ceng injury is the main reason of the rotor weight is lighter, the bearing not form enough radial load, is the main reason of the ball bearing slide ceng injury suffered by axial load change to, in addition, the rolling element and cage when the excessive motion resistance of sliding rub fault. Figure 3 engine bearing ring sliding ceng wounded traces bearing sliding ceng cause bearing components geometry size change, thus causes the vibration and noise, bearing internal clearance increases, reduce the service life of the bearing, maintains a brittle fracture even. Three, bearing skid ceng injury prevention measures: 1, the measures to prevent the bearing adopts increase drag power sliding ceng 1) Reduce the bearing clearance, the roller under the action of centrifugal force can still keep contact with the inner ring groove. However, adopt measures to reduce the clearance will lead to other serious problems, so should be treated with caution, especially for the engine hot end bearing, should be more careful. 2) Will be located in the inner ring cage, in the early days of aviation gas turbine engine, in order to solve the problem of the balance of the cage, the main bearing cage positioning in the outer ring, but this kind of design is easy to cause the bearing slide ceng damage. This is because when the cage positioning in the outer ring, exists in the oil film between outer ring and cage under the action of viscous rolled bars - hamper Keep a normal exercise, triggering sliding, sliding ceng damage. If the cage positioning in the inner ring, in the inner ring and maintain the oil film between the frame under the action of viscous rolled bars - will give Maintains a combination of a drag power make it a normal exercise. In this way, will be scheduled in the outer ring of cage to locate on the inner ring, not only to reduce the resistance, but also increase the drag power, will obviously reduce sliding ceng damage, of course it must also improve the machining precision of the cage to improve its balance. 3) Assembly, impose an additional on bearing radial or axial load, namely on bearing 'preloading', make the bearing work, between the inner, outer ring raceway and roller always have load effect, not a light load or no load, to increase the drag force. 2, the reduce block roller - Measures to prevent the bearing cage movement resistance slide ceng 1) Reduce the viscosity of lubricating oil resistance. The design of bearing inner and outer ring, should try to make the lubricating oil flow in the bearing. Outer ring is best done straight line, in order to eliminate the phenomenon of centrifugal force function decline in oil blockage in the bearing. When the retainer ring out positioning, lubricating oil in the oil film formation of the clearance viscous friction torque. 2) Use of lightweight materials for cage ( Such as the hardness of the light weight steel AISI4340) The hollow roller ( This is a study in the early 1970 s, has not been applied in the engine) In order to reduce the cage -, etc The inertia force of roller assembly. 3, in addition to the above two categories to solve bearing sliding measures, for bearing accessory drive, also can use sliding bearing material to eliminate the slippage of rolling bearings. Theoretically, accessories bearing on the transmission mechanism do not appear skid phenomenon, because the gear at work, always a radial load on a bearing. However, if the gear chain improper arrangement, or may not have on the load acting on the bearing.