A New Dynamic Model for Worm Drives

Worm drives are commonly used for power transmission. It is therefore important to study their dynamic behavior. Dynamic models of gears proved that it is possible to detect multiple defects and various types of failures. The literature showed a lack of detailed worm drive models. The existing ones are simple and envisage a minimum of degrees of freedom, which is not the case in reality. This work proposes a new tridimensional model of this type of gear. It is composed of two blocks. One block contains a worm and the other block contains a worm gear. Each block has a bearing and inertia. One inertia represents a motor and the other represents a receiver. The gear mesh stiffness between the worm and the worm gear is introduced as a trapezoidal function. The deflexion is calculated in the contact line between the worm and the worm gear. The equations of motion are obtained by using the energetic method which is “Lagrange formulism”. Then, they are solved using Newmark solving method. From the results found only acceleration is taken into account. Its signal is presented in time domains. The spectrum of the acceleration is also plotted.