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:
Jan. 06, 1981
Filed:
Jan. 18, 1979
Gary R Johnson, Yorba Linda, CA (US);
Tri-State Oil Tool Industries, Inc., Bossier City, LA (US);
Abstract
Apparatus is disclosed for drilling a pilot hole and subsequently enlarging the pilot hole in earth dormation. A dual concentric pipe string is used for circulating air downwardly through the outer pipe, a cross-over sub and through a pilot bit and upwardly through the bore hole outside the pipe string to bail cuttings, during drilling of the pilot hole. The air pressure expands the cutters of an expandible bit while a limited portion of the air supplied cools the cutters. The dual concentric pipe is made up by joints having pin and box structures which provide inner and outer flow passages and shoulders which abut between the outer members and which are resiliently sealed between the inner members.