Expansible drilling tool

Abstract

Abstract A tandem hole opener or drilling tool for underground holes is described. The lower portion of the tool is conventional. The upper portion of the tandem drilling tool has cutters mounted on a pair of dovetail members fitting into a dovetail groove in the tool body. Pipe plugs between the dovetail members wedge them into frictional engagement with the slot. An axially slidable piston has a camming end for riding along a camming ramp on each cutter arm for camming them into an extended cutting position. A bearing surface on each arm for holding them int he extended position. The piston has an axial passage with an orifice of selected diameter through which drilling fluid can flow to the cutters. A parallel passage through the tool body permits drilling fluid to be apportioned between the upper cutters and cutters on the lower portion of the tandem drilling tool. Drilling fluid pressure also stroked the piston downwardly for camming the arms into cutting position. If the piston should fail to retract when drilling fluid pressure is relieved, drawing the tool upwardly against an object of lesser diameter than the extended arms presses downwardly on the arms, thereby sliding the dovetail members in the dovetail slot and disengaging the bearing surfaces between the arms and piston so that the arms cam the piston into a retracted position.

Inventors

• 👤 T Thometz
• 👤 P Arnerich

Bibliographic Details