Thrust-responsive two-speed drill and method of operation
US5022798A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 11, 1990 |
| Grant date | Jun 11, 1991 |
| Priority date | — |
| Expiry date | Jun 11, 2010 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T408/6793
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A positive feed drill and method of operation is disclosed for drilling through a workpiece consisting of a softer overlay material on a harder base material. The positive feed drill includes a high-speed air motor and a low-speed air motor and will start and drill through the softer overlay material at the high speed but will shift to the low speed when the drill senses that the thrust on the drill bit has increased because the drill bit has contacted the harder base material. After drilling through the harder base material, the drill bit will shift to the high speed because the drill senses that the thrust on the drill bit has decreased. The drill will retract from the workpiece at high speed and will shut off. Control apparatus is provided to control the flow of air to the high-speed and low-speed air motors. Sensing apparatus senses the thrust on the drill bit and sends a signal to the control apparatus to switch between the air motors. Apparatus is included to sense the end-of-feed position, retract the spindle and shut the drill off.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.