The Mechanism of Spur Gear Tooth Profile Deformation Due to Interference-Fit Assembly and the Resultant Effects on Transmission Error, Bending Stress, and Tip Diameter and Its Sensitivity to Gear Geometry

Gear profile deviation is the difference in gear tooth profile from the ideal involute geometry. There are many causes that result in the deviation. Deflection under load, manufacturing, and thermal effects are some of the well-known causes that have been reported to cause deviation of the gear tooth profile. The profile deviation caused by gear tooth profile deformation due to interference-fit assembly has not been discussed previously. Engine timing gear trains, transmission gearboxes, and wind turbine gearboxes are known to use interference-fit to attach the gear to the rotating shaft. This paper discusses the interference-fit joint design and the mechanism of tooth profile deformation due to the interference-fit assembly in gear trains. A new analytical method to calculate the profile slope deviation change due to interference-assembly of parallel axis spur gears is presented. The effectiveness of the proposed computational algorithm to predict the deformation is demonstrated by comparing with measurements. A range of gears varying in size and interference-fit amount are analyzed by using the proposed algorithm to understand the deformation and the effect of the spur gear design variables on it. Finally, the effects of the interference-fit profile deformation and steps to mitigate the effects are discussed, along with gear train testing results and gear measurements of the gear designs that use the proposed methods.