Modeling and Prediction of Hole Profile in Drilling, Part 1: Modeling Drill Dynamics in the Presence of Drill Alignment Errors

Abstract

A dynamic deflection model that incorporates the effect of the alignment errors that arise when a drill is held in the spindle assembly has been developed. The drill is modeled as an Euler-Bernoulli beam with clamped-free end conditions. Thrust and radial forces were applied at the free end of the beam. The mechanistic model used to predict these forces has been enhanced to incorporate the effect of the alignment errors and drill vibrations. A method has been outlined to measure these alignment errors. The mechanistic model demonstrates the ability to predict the drill vibrations and the radial forces within 6 percent of the measured vibrations and forces. The effect of these alignment errors on the drill vibrations and the radial forces has also been studied.