| 摘要 |
A high speed drilling system is disclosed for high speed drilling of very small holes in workpieces such as printed circuit boards. The X-Y positioning system includes air bearings to provide lift between the stationary guide beams, the crossbeam and the top table, and further includes a vacuum preloading apparatus for providing a preloading force between the table and the guide beam. The preload force dampens Z axis oscillations which can result in drill bit breakage. The top table is a lightweight honeycomb structure, whose effective rigidity is virtually that of the guide beam due to the vacuum preloading. The system includes pairs of spindles, one a conventional spindle for drilling holes larger than about 0.125 inches, and the other a high speed spindle for drilling holes in the range of about 0.003 to 0.125 inches. The high speed spindle includes a stationary spindle body carrying the stator of the rotary drive motor. Only the spindle rotor is translated along the Z axis to perform the drilling movements. The rotor is supported within the spindle body by rotary and linear air bearings, and is axially driven by a linear motor. A toolchanger loaded by clips carrying the drilling bits is mounted on the top work table, and minimizes the time required to change drilling tools. The clips minimize the manual handling of the fragile drill bits. A vacuum hold-down appratus is employed to secure the workpieces to a drilling station.
|
