DESIGN OF HIGH-CONTACT-RATIO SPUR GEARS USING QUADRATIC PARAMETRIC TOOTH PROFILES

In order to obtain high contact ratios, the addendums of spur gears wi th involute profiles should be increased. This will increase the root stress sensitivity and the minimum tooth number of gears without under cut. This paper proposes a method of designing high-contact-ratio spur gears using quadratic parametric tooth profiles for the shorter adden dums and no undercut. A design procedure is developed and a simplified derivation of the mathematical model of parametric tooth profiles is presented. The tooth root stresses and the static transmission errors are shown to be lower than those of high-contact-ratio spur gears with involute profiles, but the contact stresses and the wear height indic es are traded off. Some examples are given to demonstrate the potentia l of this method. (C) 1998 Elsevier Science Ltd.