Method and apparatus for controlling glass drilling
AssigneeRoyal Tool, Inc.
InventorsMichael S. Overmyer, Thomas A. Peitz, Jr.
Life of this patent
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Abstract
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.
Claims21
Apparatus for successively drilling holes in workpieces at a work station comprising means for positioning a workpiece at the work station, a hollow drill bit having an axial passage, means for rotating said drill bit about said axis, means for moving said drill bit into contact with a workpiece at the work station and for advancing said drill bit as a hole is drilled in such workpiece, means for flowing a fluid through said drill bit passage, said fluid having a first flow property when said bit is spaced from the workpiece and having a second flow property when said bit is in contact with the workpiece, control means including means for determining and storing a starting position for said drill bit in response to a change from said first flow property to said second flow property as said drill bit is moved into contact with a workpiece, said control means controlling said moving means to move said drill bit to said stored starting position prior to drilling each hole.
In apparatus for drilling a hole through a sheet of material at a work station, said apparatus including first and second opposing bits, means for advancing a first bit to drill a first hole portion substantially along an axis until such first hole portion extends a predetermined distance into such material from a first side and means for advancing a second bit to drill a second hole portion substantially along said axis from a second side of the material until said second hole portion converges with said first hole portion, an improved drill calibration control comprising means for determining and storing a first starting position where said first bit contacts said first side of the material, means for determining and storing a second starting position where said second bit contacts said second side of the material, means for advancing said first drill bit to said stored first starting position prior to drilling said first hole portion, and means for advancing said second drill bit to said stored second starting position prior to drilling said second hole portion.
A method for calibrating the starting position of a drill bit in apparatus for drilling holes in glass comprising the steps of:
- a) advancing said drill bit into contact with a surface of the glass;
- b) simultaneously flowing fluid through an axial passage in said drill bit;
- c) sensing a change in a property of the fluid flowing through said drill bit when said drill bit contacts said glass surface;
- d) storing the position of said drill bit in response to the sensed fluid property change;
- and
- e) advancing said drill bit to the stored position prior to drilling a hole.
Dependencies are inferred from the claim text.