Although precision planetary gearboxes are constantly being updated and upgraded with the development of technology, their performance and other aspects have been significantly improved. However, they should still be operated in a standardized manner during use to avoid accidents. The weight of its planetary gear transmission device is generally proportional to the weight of the gears, and the weight of the gears is closely related to their material and heat treatment hardness. For example, at the same power, the weight of carburized and quenched gears will be about one-third of the weight of quenched and tempered gears. Therefore, based on the structural characteristics of planetary gear reducers and the load properties of gears, hard tooth surface gears should be widely used. There are many heat treatment methods for obtaining hardened gears, such as surface quenching, integral quenching, carburizing quenching, nitriding, etc., which should be selected based on the characteristics of planetary gear reducers. What are the methods for handling faults in precision planetary gearboxes? What are the troubleshooting methods for planetary gearboxes when encountering faults?
1. Surface quenching
The common surface quenching methods include high-frequency quenching (for small-sized gears) and flame quenching (for large-sized gears). The effect of surface quenching is best when the hardened layer includes the bottom of the tooth root. The commonly used material for surface quenching is steel with a carbon mass fraction of about 0.35% to 0.5%, and the tooth surface hardness can reach 45~55HRC.
2. Carburizing and quenching
Carburized and quenched gears have relatively maximum load-bearing capacity, but precision machining processes (gear grinding) must be used to eliminate heat treatment deformation to ensure accuracy.
Alloy steel with a pre carburizing carbon mass fraction of 0.2% to 0.3% is commonly used for carburizing and quenching gears, and its tooth surface hardness is often in the range of 58~62HRC. If it is below 57HRC, the tooth surface strength significantly decreases, and above 62HRC, brittleness increases. The hardness of the tooth center is generally recommended to be between 310 and 330 HBW. The hardness of carburized and quenched gears should gradually decrease from the tooth surface to the deep layer, while the effective carburization depth is defined as the depth from the surface to the deep layer, and the effective carburization depth is defined as the depth from the surface to the hardness of 52.5HRC.
The effect of carburizing and quenching on the bending fatigue strength of gear teeth is not only to increase the hardness of the core, but also to have residual compressive stress on the surface, which can reduce the stress in the maximum tensile stress zone of the gear teeth. Therefore, when grinding teeth, the root part cannot be ground, and when rolling teeth, a residual grinding roller should be used.
3. Nitriding
The use of nitriding can ensure that the gear teeth achieve high tooth surface hardness and wear resistance with minimal deformation. After heat treatment, there is no need for final precision machining, which improves the bearing capacity. This has special significance for internal gears that are not easy to grind.
4. Want to combine the hardness of meshing gears
When both the large and small gears have soft tooth surfaces, the hardness of the tooth surface of the small gear should be higher than that of the large gear. When both wheels have hard tooth surfaces and high hardness, the hardness of both wheels should be the same.
Choosing good materials for planetary gear reducers is beneficial for improving their load-bearing capacity and service life.