Variable-Width Drill Margin for Vibration-Stable Hole Accuracy

The patent applies local quality by making the margin width variable along the helical extension rather than uniform. Specifically, the margin features local widenings at positions where bending vibrations are most severe (typically near the tool tip and at specific intervals along the length), while maintaining narrower widths in other regions. This localized approach provides vibration damping exactly where needed without the continuous friction penalty of uniformly wide margins throughout the entire tool length.

The margin is segmented into multiple sections with different widths along its helical path. Instead of a single continuous wide margin, the design divides the margin into alternating wide and narrow segments, creating a periodic structure that provides vibration control at specific locations while minimizing overall friction contact area with the workpiece.

The patent changes the geometric parameter of the margin from a constant width to a variable width that follows a specific pattern along the helical extension. This parameter change allows the margin to provide vibration damping through its geometry alone, without requiring additional active control systems or complex manufacturing equipment. The variable width can be implemented using standard grinding or machining processes by programming the tool path to create the desired width variations.

Rather than manufacturing the entire margin with uniform high precision, the local quality principle allows for varied precision requirements along the margin length. Only the local widening sections require high precision manufacturing to achieve the correct geometry for vibration damping, while other sections can be manufactured with standard tolerances, thereby reducing overall manufacturing complexity.