Patent ID: 7351018
Filing Date: 2008-04-01
Classification: B23B,B23C,B23Q,Y10T

Abstract:
1. A method of measuring a depth of a hole in a grounded composite-material workpiece being machined by an orbital cutting process, comprising said steps of: applying a low-level electric potential to an electrically insulated cutting tool, said cutting tool having a longitudinal center axis and a cutting head with both a radial cutting edge and an axial cutting edge and with a predetermined axial length; rotating said cutting tool about said longitudinal axis; axially advancing said cutting tool towards the workpiece; determining a first zero reference position of said cutting tool as said cutting tool initially makes contact with a first outer surface of the workpiece and thereby closing an electric circuit through the workpiece; keeping a measuring element for measuring an axial movement of said cutting tool activated from said first zero reference position; performing an orbital rotation of said cutting tool about a principal axis; axially feeding said cutting tool into the workpiece; monitoring a specific character of said electric potential during an advancement of said cutting tool through the workpiece; detecting a point of breaking of said electric circuit when said cutting head of said cutting tool penetrates an opposite second surface of the workpiece; and determining, by help of said measuring element, said depth of said hole by deducting said predetermined axial length of said cutting head having penetrated the workpiece from a total length of axial advancement of said cutting tool from said first zero reference position to said point of breaking of said electric circuit through the workpiece.