Patent ID: 7637702

Claim:
A drilling method for drilling holes through a plurality of workpieces by horizontally moving a table on which the plurality of workpieces is mounted relative to a plurality of spindles juxtaposed to each other, each spindle arranged relative to a respective workpiece and rotatably holding a drill bit at an edge thereof to align an axial line of the drill bit being held therein with a center position of a part of the respective workpiece to be machined, the method comprising: detecting misalignments between an actual axial center of each drill bit from a designed axial center in X and Y directions before drilling the workpieces by rotating at least first and second drill bits with respective numbers of revolutions per minute to drill holes; drilling a first hole with the first drill bit, the first hole being selected from a hole configuration that is to be drilled more than any other hole configuration to be drilled, a hole to be drilled that has a smaller diameter than any other hole to be drilled or a hole to be drilled having higher precision than any other hole to be drilled; and drilling a reference hole to be used in post-processing with the second drill bit; wherein drilling the reference hole includes correcting the drilling position of the second drill bit based on the difference in misalignment between the axial center of the first drill bit and the axial center of the second drill bit in the X and Y directions for each spindle.