The most commonly used material of gear is steel, followed by cast iron, nonferrous metals, nonmetal, etc., but for some gears under harsh working conditions, medium carbon steel or medium carbon low alloy steel can not guarantee the service performance. At this time, alloy carbon steel (20CrMnTi, 20CrMnMo) should be selected. For heavy load and impact gear shaft and gear, 20CrMnMo is preferred to be used for manufacturing large gears. At the same time, with the improvement of strength and precision of parts made of non-metallic materials, the elastic modulus of non-metal is small, and the noise of transmission is low. Therefore, for a pair of meshing gears, nonmetal materials for small gears and metal materials for big gears can reduce the transmission noise. In the selection of non-metallic materials, the poor thermal conductivity and heat resistance of non-metallic materials should be considered. Graphene materials with good thermal conductivity and high hardness can be selected.
Selection of gear parameters
1 reduce modulus
When the diameter of the dividing circle is fixed, the effective reduction of modulus can not only reduce the sliding speed of the tooth surface, reduce the risk of wear and gluing, reduce the noise, but also reduce the processing cost.
2 gear mechanism selection
If the reduction of modulus can not meet the requirements, helical cylindrical gear transmission can be considered. When driving, the contact line of the two meshing tooth surfaces forms a spiral angle with the axis direction. Because of the role of the spiral angle, the meshing mode is changed. This not only prolongs the meshing time of each pair of teeth, but also increases the coincidence degree, thus reducing the impact, vibration and noise of gear transmission and improving transmission The stability of motion. In practical application, using helical cylindrical gear and increasing helix angle can effectively reduce noise.
1 tooth profile trimming
For a pair of meshing gears, a small part of the involute tooth profile at the top of the tooth is trimmed and cut deep to the inside of the tooth body, that is to say, the local pressure angle is larger after correction than that of the previous pressure angle. Therefore, the trimming part is more smooth and meshed with the other tooth, which increases the stability and reduces the dynamic load, thus reducing the noise.
- Increase structural damping
The gear surface is coated with a layer of internal damping material, such as damping agent, paint factor, etc. after the gear is coated with damping, the vibration amplitude will be attenuated and the elastic hysteresis effect will be produced, which can absorb the vibration energy and transform it into heat energy, so as to achieve the purpose of vibration reduction and noise reduction.