| The purpose of this thesis is to present the framework of a technology, built around a computer integrated system, for the design and manufacture of drills in general and of a new generation of micro-drills with curved helical point geometry in particular. This new drill point geometry constitutes a superset of conventional geometries (conical, ellipsoidal, cylindrical, planar, etc.) which can all be treated as special cases of curved helical points.; The intentions of this research can be divided into two domains: the establishment of flank surface models for the new curved helical drill point; and the formulation of techniques for the generation of the helical flute surfaces.; Work on the establishment of flank surface models for the curved helical drill point embraces: developing the theoretical foundations of the new curved helical drill point and comparing the drill's characteristics to other drill points. Drill characteristics of interest include (1) flank surface profile, (2) heel clearance angle distribution over the whole flank surface, (3) major cutting edge profile, (4) rake and clearance angle distributions along the major cutting edge, (5) chisel edge profile, and (6) rake and clearance angle distributions along the chisel edge. To demonstrate the advantages of curved helical drill points, several different drill point models (i.e., planar, linear helical, curved helical) are compared.; Work on the development of techniques to generate the helical flute surface embraces: developing a mathematical model for the determination of the axial-section of the tool profile for the desired groove profile (referred to as the direct problem); developing a mathematical model for the determination of the transverse-section groove profile for a given grinding tool (known as the inverse problem); and implementing severity ratio analysis to optimize the machine setting parameters. The mathematical models of the helical flute can be applied to both external and internal groove machining.; It is expected that the proposed developments will have the potential of dramatically reducing drill manufacturing costs, increasing the efficiency of the micro-drilling process, in particular for multi-layer printed circuit board manufacture, and resulting in a drill with superior performance compared to available designs. |
