1. Tooth surface wear
For open gear transmission or closed gear transmission containing unclean lubricating oil, due to the relative sliding between the meshing tooth surfaces, some hard abrasive particles enter the friction surface, thus changing the tooth profile and increasing the backlash. So that the gear is excessively thinned and the teeth are broken. Under normal circumstances, only when the lubricating oil is mixed with abrasive particles will the wear of the tooth surface abrasive particles be caused during operation.
2. Tooth surface gluing
For high-speed and heavy-load gear transmission, due to the large friction between the tooth surfaces and the high relative speed, the temperature of the meshing area is too high. Once the lubrication conditions are poor, the oil film between the tooth surfaces will disappear, making the metal of the two gear teeth. The surfaces are in direct contact so that mutual bonding occurs. When the two tooth surfaces continue to move relative to each other, the harder tooth surface will tear off part of the material on the softer tooth surface along the sliding direction to form grooves.
3. Fatigue pitting
When the two gear teeth meshing with each other are in contact, the action force and reaction force between the tooth surfaces cause contact stress on the two working surfaces. Since the position of the meshing point changes and the gear moves periodically, the contact stress is According to the pulse cycle change. Under the action of this alternating contact stress on the tooth surface for a long time, small cracks will appear at the tool marks of the tooth surface. With the passage of time, the cracks gradually expand laterally on the surface. The surface of the tooth produces a small area of spalling to form some fatigue pits.
4. Broken gear teeth
Gears under load in operation engineering are like cantilever beams. When the periodic stress of pulses at the root exceeds the fatigue limit of the gear material, cracks will occur at the root and gradually expand. When the remaining part cannot bear the transmission load, it will occur. Broken teeth. Gears may also break teeth due to severe impact, eccentric load and uneven material during work.
5. Plastic deformation of tooth surface
Under impact load or heavy load, the tooth surface is prone to local plastic deformation, so that the curved surface of the involute tooth profile is deformed.
