What are the parameters of gear? Gear parameter selection?

Alpha 1, pressure angle

The mechanical principle of the increase of pressure angle, curvature radius, inherited tooth profile tooth thickness at the nodes and tooth increases, helps to improve the bending strength and contact strength of gears.Standard pressure gear provided on the general use of our angle α =20 °. In order to enhance the bending strength and contact strength of gears used in aviation, China Aviation gears transmission standard also provides a standard pressure angle α =25 ° pressure angle α 1, the choice o

The mechanical principle of the increase of pressure angle, curvature radius, inherited tooth profile tooth thickness at the nodes and tooth increases, helps to improve the bending strength and contact strength of gears.Standard pressure gear provided on the general use of our angle α =20 °. In order to enhance the bending strength and contact strength of gears used in aviation, China Aviation gears transmission standard also provides a standard pressure angle α =25 °. But increase the pressure angle is not necessarily beneficial to transmission.The high-speed gear coincidence degree close to 2, recommend the use of the addendum coefficient is 1 ~ 1.2,the gear pressure angle is 16 ° ~ 18 °, it can increase the tooth flexible, reduces the noise and the dynamic load.

2, the small gear tooth number selection of Z1

If you keep the gear center distance a invariant, increase the number of teeth, in addition to increasing thestability of coincidence degree, improve the transmission, and also can reduce the modulus, reduce the tooth height, thus reducing the amount of metal cutting, saves the manufacturing cost. In addition, reduce the tooth height reduces the sliding speed, reduce the possibility of reducing the wear and scuffing. But the modulus, tooth thickness is thinned, they should reduce the bending strength of gear tooth. But in the tooth number within a certain range, especially when depends on carrying capacity on tooth surface contact strength, the number of teeth more for good. Closed gear transmission speed is high, in order to improve the transmission smoothness,reduce the impact and vibration, the number of teeth more for good. The number of teeth of the pinion desirablefor z1=20 ~ 40. Open (semi open) gear, tooth is mainly due to wear, the tooth not too small, the small gear tooth number should not use too much, general z1=17 ~ 20. In order to make the teeth from undercutting, for α =20 °standard spur gears, should take the Z1 ≥ 17.

3, the selection of tooth surface hardness

Pinion gear more than large, easy to wear. When the solid two pairs of gear are soft tooth surface, in order to make the life size close to the gear, the small gear tooth surface hardness is higher than that of the big gear 30-50HBS or higher. When is hardened, material, heat treatment two gear tooth surface hardness can be taken intothe same.

4, the tooth width coefficient φ D selectio

The calculation formula by the strength of the gear teeth, more wide, carrying capacity is higher; while the increase of tooth width will make the load on the tooth surface. The distribution is not uniform, so the tooth widthcoefficient should be appropriate, can be selected according to table 7. Calculation of tooth width b= φ dd1 cylindrical gear, the tooth width B1, B2 should be round. In order to prevent the two gear for assembly axial slightly dislocation and decreases the meshing tooth width, tooth width often make small gear ratio of the gear wide 5 ~ lOmm

Editor: Pu Dan