The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 25, 1976
Filed:
May. 28, 1975
James H Cobbs, Tulsa, OK (US);
Roger J Morrell, Bloomington, MN (US);
Abstract
A drill system for drilling very large holes in the earth, of diameters up to from 10 to 20 feet, by means of a rotary bit carrying a plurality of cutters, wherein the bit assembly is pressed against the bottom of the hole, so that the unit pressure against each of the cutters will be adequate for their optimum performance. The force holding the bit in contact with the bottom of the hole is created by the weight of the drilling liquid on top of the bit. A fluid seal is maintained between the outer edge of the bit and the wall of the bore hole. Liquid flows down the annulus around the drill pipe and through a plurality of orifices in the bit, terminating at the bit cutters. Rock cuttings are washed radially inwardly to a central drill pipe, which supports the bit, and through which torque is applied to the bit. The pressure drop in the orifices serves to create a differential pressure above and below the bit. The differential pressure times the exposed surface area of the bit provides the hold down force. Cuttings are lifted out of the central drill pipe by means of a smaller diameter pipe lowered inside of the drill pipe, through which compressed air is applied.