Wide transmission ratio range, high efficiency, easy to manufacture. Disadvantages:
1. The main reason is that they produce vibrations;
2. Regardless of the reasons for design, manufacturing or deformation, the shape of the involute may change along the entire tooth surface at the same time;
3. This will result in a regular, once-per-tooth excitation, which is often very strong. The resulting vibration causes both a large load on the gear and noise.
4. Furthermore, the additional strength obtained from the meshing of two pairs of teeth during the contact time cannot always be utilized because the stress is limited by the single-tooth meshing condition in the cycle.
5. It can only withstand radial loads and cannot withstand axial loads, resulting in unreasonable load distribution and reducing the overall life of the gearbox.
advantage:
The helical gears used in helical gear reducers can be considered as cylindrical gears formed by a set of thin, staggered gear plates. This means that the contact between each plate occurs at different points on the tooth profile, thus compensating for the errors of each individual plate. This compensation is highly effective due to the elasticity of the teeth. Consequently, teeth with errors within 10mm can average out the error, allowing for smoother operation under load, similar to teeth with errors within 1mm. Because approximately two teeth are engaged at any given moment (assuming an overlap ratio of approximately 1.5), this provides additional strength benefits. Therefore, stress can be built on a basis of 1.5 times the tooth width, rather than just one tooth width.
shortcoming:
1. Causes undesirable axial forces;
2. Slightly increased manufacturing costs.
Overview of spur gears and helical gears in gear reducers
1. Manufacturing and assembling a large number of thin spur gears is both difficult and uneconomical. Therefore, they are manufactured as a single unit with teeth along a helical direction.
2. Unlike spur gears, helical gears do not cause undesirable axial forces. However, the benefits in terms of vibration and strength far outweigh the disadvantages of axial thrust and slightly increased manufacturing costs. Therefore, helical gears are chosen over spur gears in gearbox manufacturing.
