INSERT DETACHABLY HOLDING CUTTING MEANS TO GROUND DRILL

Japanese Patent JP2706636

B2

PURPOSE: To mount and demount a bit by disposing an insert into a ground drill and moving a cutting means between the position of installation, where the cutting means is held by the insert, and the position of recovery, where the insert is retracted for releasing the cutting means, at the position of cutting.
CONSTITUTION: When bit segments 22 are exchanged, a tool 20 in a recovery mode is lowered into the drill 12, and introduced into the insert 24 and a recovery latch dog 154 is engaged. When the tool 20 is lifted slightly by a wire line 256, the insert 24 is retracted by the dog 154, and slid in a drive sub-assembly 18 while the bit segments 22 are released and clamped and shrunk by an elastic band 198. The tool 20 is further pulled up, and engagement with the insert 24 is released and made to reach a land ring 252. A mounting latch dog 138 and the dog 154 are compressed, the tool 20 is passed through the ring 252 and pulled up onto a ground surface, and the segments 22 are exchanged. Accordingly, bits and reamers for the ground drill can be mounted and demounted as they are left as they are positioned at the place of operation.

Macriod, Gavin Thomas
Eagan, Mathieu Vance

JP16433295A

January 28, 1998

June 29, 1995

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DOWN HOLE TECH PTY LTD (AU)

E21B10/02; E21B10/62; E21B7/00; E21B10/64; E21B10/66; E21B23/03; E21B25/02; (IPC1-7): E21B23/03; E21B10/66

Akira Asamura (3 outside)

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