How to deal with gear transmission failure?

【Faults caused by manufacturing errors】

When manufacturing gears, eccentricity usually occurs. Several typical errors, such as pitch error, base pitch error and tooth profile error. There are many reasons for these errors, including machine tool motion errors, cutting tool errors, tool errors, workpieces, improper installation and debugging of machine tool systems, fixture errors, gear deformation caused by heat treatment internal stress, and other errors. When the gear error is large, it will cause the micro-inertia of the gear transmission to interfere with the rotation, causing the gear pair to mesh and produce shock and vibration, causing greater noise.

[Faults caused by assembly errors]

Assembling gears is usually due to assembly technology and assembly method "one end contact, one end suspended" assembly error; linear deviation of the gear shaft (coaxiality, neutral error) and gear imbalance. One-end contact or linear deviation of the gear shaft will cause uneven gear loading, resulting in excessive load on a single gear, causing local early wear, and even causing gear breakage. Unbalanced gears cause shock vibration and noise.

【Faults during operation】

1. Broken gear teeth

When the gears are driven, the force of the driving gear and the reaction force of the driven gear act on the other tooth respectively through the contact point. The most dangerous situation is when the contact point is at the top of the tooth; at this time, the tooth acts like a cantilever beam, and the bending stress at the rear tooth root is the largest. If it is overloaded due to sudden overload or impact, it is easy to cause overload fracture at the tooth root.

2. Tooth surface wear or scratches

During the meshing transmission process, the gear teeth slide relative to each other, poor lubrication, dirty lubricating oil, deterioration of lubricating oil, low-speed heavy load or poor heat treatment quality will lead to adhesive wear, abrasive wear, corrosion wear, scratches, etc. on the tooth surface of the gear teeth.

3. Tooth surface fatigue

The so-called tooth surface fatigue mainly includes tooth surface pitting and spalling. The main cause of pitting is micro-fatigue cracks caused by contact stress. When the lubricating oil enters the surface crack area, the entrance is closed during the meshing process, and then squeezed. The lubricating oil in the micro-fatigue crack area expands the crack area on the tooth surface under high pressure, causing the surface metal particles to fall off from the tooth surface, leaving small pits to form pitting on the tooth surface. When the fatigue cracks on the tooth surface continue to expand deeper and farther, it will cause a large area or a large area to fall off, forming tooth surface spalling.

4. Plastic deformation of tooth surface

When the gear material is soft and the transmission load is large, it is easy to produce plastic deformation on the tooth surface. Under the action of excessive friction between the tooth surfaces, the contact stress on the tooth surface will exceed the extrusion resistance yield limit of the material, and the tooth surface material will enter a plastic state, resulting in plastic flow of the tooth surface metal. As a result, the driving gear forms a groove on the tooth surface near the pitch line, and the driven gear forms a convex edge on the tooth surface near the pitch line, thereby damaging the tooth profile.