초록 ▼

A three roller centralizer is expandable from a position with the rollers retracted to a position with the rollers extended to a larger diameter for remaining concentric in a hole being underreamed. A diagonal camming surface is fixed on the body above each such roller. An axially shiftable diagonal

A three roller centralizer is expandable from a position with the rollers retracted to a position with the rollers extended to a larger diameter for remaining concentric in a hole being underreamed. A diagonal camming surface is fixed on the body above each such roller. An axially shiftable diagonal camming surface is mounted on a piston below each such roller. Application of hydraulic pressure on the piston squeezes the rollers outwardly toward their extended position. After the rollers are fully extended, the lower camming surface can travel further so that axially extending surfaces above and below each roller prevent collapse of the rollers toward the retracted position. Links pivotably interconnect the carrier for such a roller and the body and lower camming surface respectively for retaining the rollers. Such a link has an elongated opening so that the carrier can move along the diagonal and axially extending surfaces instead of being limited to a circular path.

대표청구항 ▼

An expandable well drilling tool comprising: an elongated generally cylindrical body; means at an upper end of the body for connection to a drill string; a well wall engaging element mounted on the body for movement between a radially retracted position at least in part within the body and a radiall

An expandable well drilling tool comprising: an elongated generally cylindrical body; means at an upper end of the body for connection to a drill string; a well wall engaging element mounted on the body for movement between a radially retracted position at least in part within the body and a radially extended position at least in part outside the body; first camming means fixed on the body for camming the wall engaging element from the retracted position toward the extended position; second camming means for camming the wall engaging element from the retracted position toward the extended position, the wall engaging element being between the first and second camming means in the retracted position; and means for shifting the second camming means axially along the body toward the first camming means for squeezing the wall engaging element toward the extended position.