Tribological investigations into the operational behavior of self-piloting drilling tools

摘要

Deep-hole drilling tools are equipped with guide pads, which guide and support the tool in the hole. Wear on the cutting edges has only a secondary effect on the hole surface quality, because it is the guide pads that exert the final forming influence on the wall of the hole. The wear behavior of guide pads is quite different from that of the cutting parts. Materials which are generally known to be unsuitable for use as cutting material when cutting steel bring good results when used as pad materials. This paper describes methods with which to optimize the guide pads of drilling tools in order to influence tool life and workpiece quality. It includes investigations on a specifically developed model test stand, which made it possible to analyze the tribological processes between the pad and the wall of the hole independently of the actual drilling process. Finite element simulations for the purpose of guide pads, in terms of the choice of design best suited to the load conditions, are also described. Deep-hole drilling tests give a proof for the increased cutting capacity being achieved with new guiding pads.