Analysis of Drill Stress by Three-Dimensional Photoelasticity

Abstract

An exploratory drill point stress analysis was obtained experimentally using a three-dimensional photoelastic technique. A drill model was stress-frozen under simulated drilling conditions and seven segments were sliced perpendicular to and along the cutting edge for subsequent photoelastic analysis. Isochromatic fringe patterns from slices close to the drill periphery suggest an action analogous to orthogonal cutting. Generally, stresses become more compressive as the cutting edge or the outer corner is approached. A maximum shear stress was found to exist along the cutting edge at a point about three-fourths of the distance from the chisel edge and was noted to be similar to a previously determined cutting edge temperature distribution.