The straight bevel gear is the simplest form of the bevel gear. Its design, manufacture, installation and maintenance are relatively simple. It is commonly used in the transmission of the cross shaft where the axial thrust bearing cannot be installed, but the coincidence is small and the noise is large. Therefore, its use has great limitations. Generally, it is used in the transmission with low relative speed. The linear speed is usually not more than 5m / s and the rotational speed is not more than 1000r / min.
2、 0 °
The 0 ° spiral bevel gear is a kind of gear pair with incomplete conjugate local point contact. Because the tooth line of 0 ° spiral bevel gear is spiral, there is axial force in the transmission, and the axial force changes with the steering direction. The spiral angle of the midpoint of 0 ° spiral bevel gear is 0, and the axial force is not very large. In some cases, the support system can not be changed, similar to the straight bevel gear transmission, which can be interchanged in many applications.
However, the transmission stability of the 0 ° spiral bevel gear is much greater than that of the straight bevel gear, which can be used in the high-speed transmission with the online speed of 60m / s. The contact condition of straight bevel gear tooth surface can not avoid edge contact, and the helix angle of the center point of 0 ° spiral bevel gear is equal to 0, it is a point contact gear pair, which can easily adjust the contact area mark of tooth surface to avoid edge contact, therefore, it is not easy to produce edge contact, eccentric load and stress concentration phenomenon, and the contact of concave and convex tooth surface makes it have better strength performance of teeth, the same regulation The 0 degree spiral bevel gear of lattice can bear more load. Therefore, compared with the straight bevel gear, the 0 degree spiral bevel gear has the advantages of more stable transmission, greater load and power transmission and longer service life.
Li hid of Chongqing University made a comparative analysis of the transmission characteristics of the contact reaction force, contact spot position, stress and gear vibration of the 0 ° spiral bevel gear and the straight bevel gear through the finite element model, and obtained the following conclusions:
In the case of contact force, the fluctuation amplitude of the contact force of the straight bevel gear is 20 times of that of the 0 ° spiral bevel gear after it is stable. At the same time, after FFT transformation of the contact force of the straight bevel gear, the frequency and amplitude are large, and the meshing stability is poor.
From the point of view of tooth contact area, under ideal conditions, the contact spots of the straight bevel gear are evenly distributed along the tooth direction, and the distribution of the 0 ° spiral bevel gear is relatively concentrated. For the pinion, the contact force of the straight bevel gear is 1.4 times of the basic stress of the tooth surface of the 0 ° spiral bevel gear, 1.3 times of the root tensile stress of the 0 ° spiral bevel gear, and 1.3 times of the root compressive stress of the 0 ° spiral bevel gear .18 times. For large gears, the contact stress of straight bevel gear is 1.03 times of that of 0 ° spiral bevel gear, 1.26 times of that of 0 ° spiral bevel gear, and 1.57 times of that of 0 ° spiral bevel gear.
In terms of vibration, the large end displacement amplitude of the straight bevel gear is 2.54 times of that of the 0 ° spiral bevel gear, the large end acceleration of the straight bevel gear is 2.8 times of that of the 0 ° spiral bevel gear, and the vibration of the 0 ° spiral bevel gear is smaller.