Method and apparatus for drilling fine holes in frangible workpieces
US4052132A · kind A · utility
Inventor
Key dates
| Filing date | Nov 10, 1975 |
| Grant date | Oct 4, 1977 |
| Priority date | — |
| Expiry date | Nov 10, 1995 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T408/17
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A drilling system and method for use on thin frangible workpieces, such as watch crystals and the like, in which the speed of rotation and pecking motion of the drill are programmed to execute a preset schedule of changes with minimal human intervention. In a preferred embodiment, the drill is mounted over the workpiece, which is pneumatically clamped on the work surface in a shallow water bath. The vertical pecking motion of the drill is under the dual control of a primary cable tensioned by weights on one end under control of a solenoid; and a secondary cable, the tension of which is responsive to the rotation of a master cam. The latter also initiates relay action for sequential operation of controls. The drill operates at an initial, relatively low rotational speed and a brisk pecking motion. At a preselected point near the lower end of the drill hole, the rotational speed of the drill is shifted to "high", and the pecking motion is slowed. Simultaneously, weights are lifted from the end of the primary cable, releasing the drill bit for the final slow descent through the remaining portion of the workpiece, reducing the possibility of breakout.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.