Drilling apparatus

Claim 2

A drilling apparatus comprising a hollow elongated body having one end opened and one opposite end closed; a piston axially displaceable in said body, said piston having a leading end and a trailing end, said trailing end forming with said closed end of said body an expansible chamber; a shaft supported in said piston and extending through the leading end thereof; a cutting head fixedly mounted on one end of said shaft adjacent the leading end of said piston; drive means for applying torque to said shaft; and hydraulic conduit means communicating with said expansible chamber for introducing a working fluid therein to thereby axially displace said piston in said hollow body; said working fluid being maintained under a predetermined positive pressure to advance said cutting head with a constant cutting feed.

Claim 3

A drilling apparatus as defined in claim 1 wherein said cutting head includes a core drill made of a highly resistant abrasive material.

Claim 4

A drilling apparatus as defined in claim 1 wherein said cutting head includes a core drill made of a material chosen from the class including diamond and cemented carbide.

Claim 5

A drilling apparAtus as defined in claim 3 wherein said cutting head includes an elongated hollow cylindrical member supporting said core drill at one end thereof.

Claim 6

A drilling apparatus as defined in claim 1 wherein said drive means are enclosed in said piston and further comprising conduit means extending through the trailing end of said piston and the closed end of said body for actuation of said drive means.

Claim 7

A drilling apparatus as defined in claim 5 wherein said drive means is an air driven motor and said conduit means include air passageways to said air driven motor.

Claim 8

A drilling apparatus as defined in claim 6 wherein said piston includes a scraping member fixed to the leading end thereof and adapted to contact the inside wall of said hollow body, said scraping member being made of a high-temperature resistant material and acting as a heat shield for protecting said air driven motor inside said piston.

Claim 9

A drilling apparatus as defined in claim 6 further comprising securing means for fixing said air passageways to the outer wall of said hollow body to prevent relative rotation therebetween.

Claim 10

A drilling apparatus as defined in claim 8 wherein said securing means include a bracket fixed to said air passageways and rod means having one end fixed to the outer wall of said body and the other end slidably received in said bracket.

Claim 11

A drilling apparatus as defined in claim 8 wherein said securing means include a bracket fixed to said air passageways and rod means having one end fixed to said bracket and the other end secured to a piston slidably received in an hydraulic cylinder fixed to the outer wall of said hollow body, said cylinder being in fluid communication with said hydraulic conduit means.

Claim 12

A drilling assembly for drilling holes in pipes under high internal pressure and temperature, comprising a tubular member adapted to be attached at one end thereof to a pipe to be drilled, a gate valve secured to said tubular member; a hollow elongated cylindrical body having one end connected to said gate valve and the opposite end closed; a piston axially displaceable in said body, gate valve and tubular member; said piston having a leading end and a trailing end, said trailing end forming with said closed end of said body an expansible chamber; a shaft supported in said piston and extending through the leading end thereof; a cutting head fixedly mounted on one end of said shaft adjacent the leading end of said piston; drive means for applying torque to said shaft; and hydraulic conduit means communicating with said expansible chamber for introducing a working fluid therein to thereby axially displace said piston in said hollow body; said working fluid being maintained under a predetermined positive pressure to advance said cutting head with a constant cutting attack on said pipe.

Claim 13

A drilling assembly for drilling holes in pipes under high internal pressure and temperature, comprising a tubular member adapted to be attached at one end thereof to a pipe to be drilled, a gate valve secured to said tubular member; a hollow elongated cylindrical body having one end connected to said gate valve and the opposite end closed; a piston axially displaceable in said body, gate valve and tubular member; said piston having a leading end and a trailing end, said trailing end forming with said closed end of said body an expansible chamber; a shaft supported in said piston and extending through the leading end thereof; a cutting head fixedly mounted on one end of said shaft adjacent the leading end of said piston; drive means for applying torque to said shaft; and hydraulic conduit means communicating with said expansible chamber for introducing a working fluid therein to thereby axially displace said piston in said hollow body; said working fluid being maintained under a predetermined positive pressure to advance said cutting head with a constant cutting attack on said pipe.

Claim 14

A drilling assembly as defined in claim 11 wherein said one end of said tubular member extends in a plane oblique relative to the longitudinal axis of said tubular member.