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U.S. Department of Energy
Office of Scientific and Technical Information

Underreamer cutter arm

Patent ·
OSTI ID:6559600
A hole drilling tool, useful in mining operations for enlarging the lower portion of a hole for explosives, is described. This underreamer has arms movable between a retracted position and an extended position for under-reaming in response to weight of the drill string above the tool. The 2 cutter arms are urged outward into their extended position by a cam connected to the upper end of the drill string. In effect, the cutter arms are connected to the lower end of the drill string which can telescope relative to the upper end. An air-flow passage extends from the tool body through the cutter arms for cooling the cutter bearings. (12 claims)
Assignee:
Smith International Inc.
Patent Number(s):
US 3949820
OSTI ID:
6559600
Country of Publication:
United States
Language:
English