| Industrial practice continuously presents new challenges to drilling process development and improvement. One of the major challenges is to develop some predictive models for drilling process performance evaluation so that drill design and drilling process development can have a scientific basis and a short lead time. Some other major challenges include developing high-throughput drilling process to significantly increase productivity, and performing dry drilling to eliminate ecological, health and economical problems induced by the machining coolant.; Motivated by these challenges, this thesis work explores three areas: drilling process modeling, drill design for high-throughput drilling, and dry drilling process development.; Several process models are presented in this work. A mechanistic approach is adopted to develop a drilling force model in a vectorial form, which, combined with a simplified material calibration procedure applicable to arbitrary drill geometry, simplifies and expedites the drilling force prediction. A finite element model with continuous remeshing is developed for the orthogonal cutting process with edge-radius tool, with the focus on obtaining some understanding of the basic mechanics of the process and investigating a few key process characteristics. A chip evacuation model based on chip dynamics is developed for the first time for drilling process. The model is focused on discontinuous chips, and studies the effects of various process parameters on the chip evacuation.; A finite element model and an optimization algorithm are used to analyze and improve the torsional stiffness of the drill. Both drill cross-sectional profile and coolant hole size and location are studied to obtain some new drill design guidelines.; Dry drilling of aluminum alloys is investigated through extensive experimentation. Based on the chip evacuation model and the experiments, a new method is developed for dry drilling aluminum, in which tool life is significantly improved to an extent comparable to that in wet drilling. |
