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:
Jun. 23, 1981
Filed:
Jan. 23, 1980
Applicant:
Inventors:
Bernt S Liljekvist, Sandviken, SE;
Anders E Persson, Sandviken, SE;
Assignee:
Sandvik Aktiebolag, Sandviken, SE;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
E21B / ; E21B / ; E21B / ;
U.S. Cl.
CPC ...
175 57 ; 175 53 ; 175344 ; 175376 ;
Abstract
A bore head for reaming a pre-drilled hole in raise boring or for similar earth cutting operations comprising at least two sets of roller cutters. The roller cutters in the same set of cutters have the same number of rows of cutting means. The roller cutters are mounted in pairs on each side of the rotational axis of the bore head. During rotation of the bore head the cutting means move along concentric circles. In order to change the distance between two consecutive circles a roller cutter in one of the pairs of cutters is replaced by a roller cutter of the other set of cutters.