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What Are The Special Requirements For Aircraft Engine Bearings

wallpapers News 2020-04-09

Aircraft engines have relatively high requirements on bearings, mainly high speed, high-temperature resistance, and high reliability. Bearings vary in size from small to large. The smallest "mini-bearing" in the world has an inner diameter of 0.6 mm x an outer diameter of 2.0 mm x thickness of 0.8 mm and is used for micro-motors. Large bearings, with an outer diameter of 6 meters and a weight of more than 15 tons, are used in large shield machines for tunneling. This type of shield machine was used when the cross-sea tunnel was excavated under the Dover Strait connecting Britain and France, and this type of significant bearing was used. When running at high speed, since the inner ring of the bearings rotates, the centrifugal force is tremendous, and the cross-section of the inner circle of the bearing is subjected to hoop tensile stress, so there must be no microscopic cracks on the surface of the inner ring to avoid crack propagation under tensile stress, so it is often used AISI M50NiL material is used as inner ring.

Because the rotation speed is very high, to reduce the extra load caused by the centrifugal force of the steel ball, generally lighter weight and more upper hardness ceramic material, such as silicon nitride (Si3N4) or titanium carbide (TiC), is used as the steel ball material Sometimes, to increase the wear resistance of the inner and outer rings of the bearing and reduce friction, the inner-outer ring raceway is also sprayed with ceramic.

The engine temperature can be more than 300 ° C. The maximum temperature is above 1500 ° C. The bearing temperature is only 300 ° C. This is the credit of the lubrication system. The bearings lubrication system also has the primary function of cooling the engine bearing lubrication. It is similar to the lubrication of general bearings. Because the bearing speed is too high to use contact seals, the engine bearings use a labyrinth seal. Still, the lubricant he uses is much better because the operating temperature is too high, general lubricants are natural. It is oxidatively deteriorated, so synthetic oils are generally used.

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