CHISEL rotary drilling with the caliber venues, having improved handling and reduced wear

摘要

1. The rotary drill bit for rotary drilling a borehole formation comprising a bit body having one end adapted for attachment to a drill string, the bit rotational axis passing through the bit body, a plurality of blades disposed on outer portions of the bit body, wherein at least one calibrating of the blades has a platform with an outer surface adapted for contact with surrounding portions of the borehole formed by the drill bit, the outer surface of the gauge pad is located upstream wellbore edge to the front edge and rear edge projecting downhole from it, the front edge of the gauge pad partially bounded first radius extending from the bit axis of rotation to located uphole edge, the trailing edge of the gauge pad partially restricted second radius extending from bit rotation axis and located uphole edge, and the first radius is greater than the second radius, when measured in a plane extending generally perpendicular to the axis of rotation of the bit. ! 2. Chisel rotary drill according to claim 1, wherein the outer surface of the gauge on the site of at least one vane further comprises a generally continuous conical surface radially extending from a point adjacent the front edge to a location near the trailing edge of the gauge pad. ! 3. Chisel rotary drill according to claim 1, wherein the outer portion of the gauge pads on at least one vane further comprises a generally curved surface extending from the leading edge to the trailing edge of the gauge pad, a commonly