| 摘要 |
<p>A drilling machine and method of operation for drilling through holes in a workpiece while minimizing penetration of the drill tool into a back-up material which supports the workpiece. Before placing the workpiece on the machine, the vertical position of the back-up material is mapped. After selection of the drill site, the mapped position of the backup material proximate the drill site is retrieved. Using this information, a computer controller determines an absolute vertical position for a lower limit of the drill stroke. This lower limit is independent of the top of the workpiece or the thickness of the workpiece, thus eliminating the need to determine either of those values. The drill stroke is terminated once the drill tool reaches the lower limit, which is a nominal depth below the mapped position of the back-up material, insuring that a hole is completely drilled through the workpiece, while minimizing penetration of the back-up material. Also, vertical position sensors used for prior art depth control drilling can be used in the system disclosed.</p> |
