Optimization of Spiral Bevel Gear Based on Tooth Height Factor

The tooth height coefficient of hypoid gear pair mainly includes working tooth height coefficient and tooth crest height coefficient, which mainly affects working tooth height and pitch position, and has a great influence on end coincidence and stress distribution of gear pair.

1. Influence of working tooth height coefficient on bearing capacity

Working tooth height coefficient mainly affects the end-face coincidence of gear pair. Taking a hypoid gear pair as an example, the influence of working tooth height coefficient on the end-face coincidence of gear pair is studied (keeping other parameters unchanged).

As the tooth height increases, the contact ellipse area of the gear pair increases, thus improving the end coincidence.For example, the working teeth height coefficient increases from 3.7 to 4.3, and the end-face overlap increases from 0.894 to 1.019. The increase of end-face overlap reduces the rodent impact and rodent impact on the one hand, and on the other hand, increases the contact area while reducing the bending stress and contact stress on the other hand.

2. Influence of crest height coefficient on bearing capacity

The crest height coefficient determines the crest height of the large wheel.The higher the crest height coefficient is, the higher the crest height of large gear is, the farther the pitch line is from the root of small gear, and the greater the bending moment of small gear, the higher the bending stress will be. Therefore, excessive crest height coefficient is unfavorable to small wheel.

The top-height coefficient only affects the end-face coincidence, which increases from 0.1 to 0.3 and from 0.924 to 1.015. The increase of end-face coincidence is beneficial to vibration and noise reduction.The contact stress increases slightly with the increase of the crest height coefficient.

The bending stress of small wheel increases by 14 MPa and that of large wheel decreases by 28 MPa.Increasing the crest height factor can improve the end coincidence of the gear pair on the one hand, but increase the contact stress and bending stress of the small wheels on the other hand. Therefore, both effects should be considered comprehensively in the optimization. In order to increase the coincidence, the crest height factor can be increased appropriately, and then the life balance of the large and small wheels can be adjusted by the tooth thickness.