Views: 1 Author: Site Editor Publish Time: 2020-08-24 Origin: Site
Fatigue pitting is also the most common form of gear wear. In the operation engineering of the reducer gear, the surface of the gear is subjected to the contact stress of the pulsating cycle. As the number of operating loads increases, the surface material of the gear becomes fatigued, which will be generated under the surface Micro-cracks, micro-cracks gradually expand to form fatigue pitting corrosion. Pitting corrosion generally occurs near the pitch line circle, because in the gear bonding process, the first form of friction is sliding friction, where the friction is relatively large, when it is bonded to the pitch line When the circle becomes rolling friction, the friction is the smallest, and then it becomes sliding friction again. The degree and time of pitting corrosion mainly depend on the number of loads, the hardness of the material surface, the contact stress, the surface roughness, and the lubricant and lubricant film Thickness etc.
If the lubricating oil is improperly selected (viscosity, base oil properties, pour point, etc.), or poor lubrication (splash lubrication, full pressure lubrication, gravity lubrication), it will cause or produce fatigue pitting. Low viscosity oil has better fluidity The thickness of the oil film formed by the lubricating oil is too thin and the strength is insufficient, which often forms boundary lubrication conditions. The thickness of the oil film of the lubricating oil is less than the comprehensive roughness of the gear surface, which promotes direct contact with the convex points on the tooth surface and instantaneous heat generation, which causes the temperature of the lubricating oil to rise At this time, the viscosity of the lubricating oil drops again, and the lubricating oil with good fluidity is easy to penetrate into the surface cracks and pitting corrosion, and the development of the crack tendency is accelerated under the squeeze action of the load. The lubricating oil film established by the high viscosity oil is relatively relatively Thick, and the oil film thickness is relatively uniform, the friction force of the contact surface can be completely transformed into the force of the molecules itself, and the contact stress distribution is relatively uniform, avoiding the damage to the contact surface by the maximum stress, and greatly reducing the wear of the gear surface. In other words, appropriately increasing the viscosity grade of the lubricating oil can effectively reduce the tendency of pitting on the gear surface, and adding anti-micropitting additives to the lubricating oil can effectively slow down the occurrence of pitting.
When the anti-foaming performance of the lubricating oil is not good, the lubricating oil will easily form foam due to the long time stirring the lubricating oil during the operation process. Explosion will form a greater impact on the surface of the gear and increase the risk of pitting on the surface of the gear; when the air release performance of the lubricating oil is not good, it will also form cavitation and aggravate the pitting corrosion. The amount of oil supply and lubrication methods (splash lubrication, full pressure lubrication, gravity lubrication) also have an impact on pitting. The gear box has too much oil, and the lubricating oil film is relatively thick. During the gear bonding process, it is always squeezed on the surface of the gear. Locally generated high pressure will cause a small part of the lubricating oil to be squeezed into the existing pitting corrosion and cracks. The formation of high stress will promote the continuous deterioration of the gear surface and increase the tendency of pitting corrosion. Therefore, the use of lubricating oil in the gearbox should be fully considered. The lubrication amount recommended by the equipment manufacturer should be followed, and the gear should be sufficiently lubricated without aggravating the formation of pitting corrosion. Achieve good lubrication effect.