Mathematical model for helical drill point

Helical drill points provide a superior cutting performance in drilling operations, particularly in micro-hole drilling. This paper presents a comprehensive and straightforward method for the design of helical drill points. The proposed method has three particular features. Firstly, a mathematical model of the helicorid grinding surface is developed. This model allows the normal and tangential vectors of the abrasive wheel to be obtained explicitly. Secondly, the mathematical models of the flute and flank surfaces are integrated and therefore the cutting and chisel edges can be obtained by numerical calculation. Finally, the derivation of the model is straightforward and expresses the drill's characteristics (e.g. the semi-point angle, chisel edge, lip clearance angle, heel clearance, angle tool cutting edge inclination, normal rake angle and normal clearance angle) in accordance with all current international standards. The proposed model is capable of describing a wide range of helical drills. The methodology presented in this study facilitates the production of helical drills on a 6-axis CNC grinding machine. (c) 2004 Elsevier Ltd. All rights reserved.