Apparatus and method for accurate countersinking and rivet shaving for mechanical assembly operations

A method for performing accurate machine operations on mechanical assemblies with an apparatus which includes a first spindle for holding a cutting tool for performing very accurate machine cutting operations, comprising the steps of:

• obtaining an initial nominal position of the cutting tool relative to the workpiece;
• moving the first spindle toward and away from a workpiece which comprises at least two workpiece elements to be joined together, the workpiece having a near surface relative to the cutting tool, whereas the cutting tool has an initial apex position in its movement relative to the workpiece determined by said initial nominal position of the cutting tool;
• clamping the workpiece elements and stabilizing them in a fixed position with a pressure foot assembly, the pressure foot assembly having an aperture through which the cutting tool can move to contact the workpiece;
• determining the position of the cutting tool following contact between a tip end of the cutting tool and the near surface of the workpiece after clamping of the workpiece by the pressure foot assembly has occurred and before drilling begins;
• and
• adjusting the initial apex position of the cutting tool in accordance with the determined position of the cutting tool to achieve a very accurate cutting operation in the workpiece.

An apparatus for performing accurate machine operations on mechanical assemblies, comprising:

• a first spindle for holding a cutting tool for machine operations;
• a pressure foot assembly for clamping a workpiece comprising at least two workpiece elements;
• a moving assembly for moving the first spindle to a point forward of the pressure foot;
• means for moving the pressure foot forward to clamp the workpiece, wherein the first spindle and the cutting tool move forwardly with the pressure foot;
• thrust control for the first spindle, permitting selective reduction of thrust such that, as the pressure foot moves toward and clamps the workpiece, a tip of the cutting tool, after initial contact with a near surface of the cutting tool, maintains contact with the workpiece but does not indent the assembly;
• means for determining the relative position of the workpiece and the cutting tool upon completion of clamping;
• and
• means for adjusting the apex position of the cutting tool in accordance with said determination to achieve very accurate cutting of the workpiece.