Thrust-responsive two-speed drill and method of operation

Details Thrust-responsive two-speed drill and method of operation Thrust-responsive two-speed drill and method of operation

1990-06-11

1991-06-11

Schwartz, Larry I.

Cutting by use of rotating axially moving tool

Processes

Bit detachable

408 9, 408 12, 408 14, 408702, 408137, B23B 3500

Patent

active

050227980

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.

REFERENCES:
patent: 2547079 (1951-04-01), Gerentes
patent: 4198180 (1980-04-01), Schultz
patent: 4688970 (1987-08-01), Eckman
patent: 4745557 (1988-05-01), Pekar et al.

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