Method and apparatus for controlling glass drilling

摘要

A method and apparatus for controlling glass drilling in which the starting position for the drill bit is calibrated prior to drilling. The drill bit is initially spaced close to the surface to be drilled and the rotating bit is slowly advanced toward the surface while a cooling fluid is discharged through an axial passage through the bit. Contact between the bit and the surface is determined by sensing either an increase in the fluid back pressure or a decrease in the fluid flow rate. The determined bit position is stored and used as a starting position when subsequently drilling holes. The starting position may be modified for subsequent workpieces to compensate for bit wear.