Large diameter hole opener for earth boring

Claim 1

A well bore expanding tool adapted to be inserted into a well bore for an expansion of a portion of the bore beneath the earth''s surface comprising: an elongate tool body adapted to be affixed to a rotary drill string; a plurality of cutter blades pivotally mounted upon said body, said blades being circumferentially spaced about said body and in transverse alignment; a mandrel longitudinally movable within said body; means for moving said mandrel downwardly in response to fluid pressure in said drill string; means interconnecting said mandrel and said blades whereby said blades are pivoted outwardly and upwardly to an opened cutting position in response to downward movement of said mandrel; cutting edges along the upper surface of each of said blades adapted to expand the well bore as said drill string is raised and rotated with said blades expanded; a fluid conducting bore extending longitudinally through each of said cutter blades, a series of fluid outlets spaced longitudinally along the length of said blade in communication with said bore; a fluid conducting conduit extending through said tool body to a fluid outlet proximate each of the pivot points for said blades; and said fluid conduit and said fluid bore being so constructed that they are in fluid communication at the open position of said blade whereby fluid is conducted outwardly from said blade toward the surface of the well bore being cut when said blades are in the cutting position.