The Effects of Static Frictions on the Drilling Process of Hammer-Drill System

Static frictions are neglected in many dynamic analyses mainly due to inappropriate modeling of them. A new dynamic model describing the nonlinear and discrete features of static frictions is proposed in this paper. Using the new model, the drilling process of the hammer-drill system utilized in the EAS’ Mars mission is analyzed. It is shown that most important functions of the hammer-drill system are realized by static frictions, which were not observed before the introduction of the new model of static frictions. Static frictions provide the torsional force on the drill and make the normal impact happen before the rotation, which is critical to the efficiency of the cutting process of the hammer-drill system.Copyright © 2005 by ASME