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

Retractable drill bits

Patent ·
OSTI ID:5258664
A rotary well drill bit is lowered through drill pipe with cutters in tandem array, the cutters being expanded outward and locked to the lower end of the drill pipe. The cutters can be pulled by a wire-line device back into the drill pipe and elevated through the drill pipe to the drilling rig for replacement or inspection. The bit can include a core barrel apparatus for producing a core during drilling of the hole, the core apparatus being lowered and elevated through the drill pipe with the tandem cutters. (24 claims)
Assignee:
Christensen Diamond Prod. Co.
Patent Number(s):
US 3437159
OSTI ID:
5258664
Country of Publication:
United States
Language:
English