Pitting corrosion of gears is caused by the action of cyclic and alternating pressure on the surface metal materials of gears under long-term load. After long-term operation, fatigue peeling occurs on the contact surface of gears and pits appear.
In other words,fatigue pitting corrosion is a common fault of planetary reducer. Fatigue pitting corrosion begins with small diameter and shallow, and mostly occurs below the pitch circle and pitch circle.The speed of development is very fast. If it is not found in time, it will lead to the flaking of large pieces of gears, eventually lead to the scrap of gears, and the reducer can not continue to use.
Under the action of cyclic and alternating pressure, surface metal materials from plastic deformation---micro crack---crack propagation ---surface metal shedding (pitting corrosion), after long-term operation, there is pitting corrosion. For example, one of the failure forms of gears after long term work is pitting corrosion.
Reasons and Countermeasures:
Taking the fatigue pitting corrosion of gear reducer motor as an example, the causes of fatigue pitting corrosion are explained and the countermeasures are pointed out.
(1) The pitting corrosion caused by poor heat treatment of materials is often smooth, and the pitting corrosion caused by inhomogeneous heat treatment is often concentrated in a certain position of the gear. Gears need to be updated.
(2) Unauthorized use of load increases, causing fatigue pitting on the tooth surface. This can reduce the use of load.
(3) The selection of lubricating oil is unreasonable, because the viscosity of lubricating oil used is too low or invalid, there is no oil film between the tooth surface, and the tooth surface is directly contacted with pitting corrosion. It is necessary to replace a reasonable lubricating oil or increase the viscosity, which can quickly improve the pitting corrosion of the tooth surface.
(4) Too much vibration of the drive bearing of the gear reducer motor results in the increase of load. The vibration of the shafting is caused by the large clearance between the bearing and the bearing hole and the stiffness of the drive bearing, which results in the increase of the transmission load of the gear and the fatigue pitting corrosion of the tooth surface. The service life of the gear can be prolonged by replacing the transmission shaft with greater stiffness, repairing the bearing clearance or reducing the lifting speed.
(5) The bad installation of the reducer of the hoisting mechanism results in the local contact of the tooth surface, and the deviation of the axis of the gear can cause the local contact load of the tooth surface to be too large and cause fatigue pitting corrosion. At this time, the contact area of the tooth surface can be increased by adjusting the level of the body (adding copper or steel gaskets between the decelerating block and the base or the base), and the pitting corrosion condition can be improved. The contact area can also be improved by running-in and grinding.
(6) Other factors may also cause fatigue pitting on the tooth surface. For example, unreasonable selection of tooth surface parameters, interference of tooth top, bottom viscosity of gear manufacturing, tooth surface roughness and so on, we should carefully analyze various unfavorable factors, concrete analysis of specific problems, and take different measures to solve them.
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