EXPANDABLE BIT

摘要

An expandable drill bit for use with earth drilling equipment. The bit includes arms held in a closed position, so that the bit may be inserted through casing or a small bore hole. The arms are expandable to create an expanded drill bit having a crown profile common to a solid crown bit. The arrangement of the arms provides a short gauge length so that the expanded bit is steerable downhole. Embodiments of the expandable drill bit are detailed to show mechanisms for actuating the arms between the open and closed positions.