Analysis of the Chisel Edge and the Effect of the d-Theta Relationship on Drill Point Geometry

Following the investigation of drill point geometry previously reported [1, 2], the chisel edge profile and the chisel edge angle are analyzed mathematically. The relationship between the cone semiangle, θ, and the x-coordinate of the cone vertex, −d, is derived for a given chisel edge angle and nominal relief angle at the outer corner. This relationship is used to study the effects of grinding cone parameters on drill point geometry. The analysis indicates the existence of an optimum θ value for best drill performance.