What are the reasons for the failure of toothed chain teeth?

Question

Accepted Answer

Toothed chain plate is an important mechanical root piece used throughout. It is mainly used in high speed, heavy load, low noise and large center distance. Its transmission function is better than toothed belt drive, gear transmission and chain. Transmission, so the gear of the toothed chain plays an important role, but if the gear of the toothed chain fails, it will affect its mission efficiency, so let us first understand the way the lower gear chain gear fails.

1. Tooth surface wear: Regarding open gear transmission or closed gear transmission with unclean lubricating oil, because of the relative sliding between the tooth surfaces, some hard abrasive grains enter the conflicting appearance, and then the tooth profile is changed. The side gap is increased, so that the excessive gear thinning causes the tooth to break. Under normal conditions, only when the abrasive grains are mixed in the lubricating oil, the wear of the tooth surface will be caused during operation.

2. Tooth surface gluing: In the gear transmission of high speed and heavy load, due to the conflicting force between the tooth surfaces, the relative speed is large, causing the temperature in the meshing zone to be too high. Once the lubrication condition is poor, the oil film between the tooth surfaces will disappear. The metal appearance of the two teeth is directly touched and then bonded to each other. When the two tooth surfaces continue to move relative to each other, the harder tooth surface tears part of the data on the softer tooth surface in the sliding direction to form a groove.

3. Weak pitting: When two teeth are engaged with each other, the effect force and counter-effect between the tooth surfaces cause the contact stress on the outer surface of the two missions, because the orientation of the meshing point is changed, and the gear is made periodically. The movement, so the touch stress is changed by the pulsating cycle. For a long time under the effect of such alternating touch stress, a small crack will appear at the tooth mark of the tooth surface. Following the passage of time, the crack gradually expands laterally in the surface layer, and the crack forms a ring shape, so that the tooth teeth A small area of spalling occurs on the exterior to form some tired shallow pits.

4, the tooth broken: in the operation of the load bearing gear, like the cantilever beam, the root of the pulse of the periodic stress beyond the fatigue limit of the gear data, will crack at the root, and gradually expand, when the rest Broken teeth can occur when the transmission load cannot be tolerated. Gears can cause broken teeth due to severe impact, partial load and uneven material in the mission.

5. Plastic deformation of the tooth surface: Under the impact load or heavy load, the tooth surface is prone to partial plastic deformation, and then the curved surface of the involute tooth profile is deformed.