Expansible rotary drill bit

Claim 2

In a rotary drill bit to be lowered in a bore hole: a main body; means for rotating said body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body and for rotation with said body; a plurality of roller cutters carried by each supporting member for enlarging the diameter of the bore hole and thereby produce a transverse shoulder therein and for operation upon the transverse formation shoulder; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; and means operable while said main body, supporting members and cutters are being rotated by said rotating means for expanding said supporting members and cutters carried thereby laterally outwardly of said body for enlarging the bore hole diameter and for operation of said cutters upon the transverse formation shoulder.

Claim 3

In a rotary drill bit as defined in claim 1; said cutters laterally spaced from each other being rotatable about axes lying in a plane radial of the longitudinal axis of said body.

Claim 4

In a rotary drill bit as defined in claim 1; one of said cutters carried by each supporting member extending laterally outwardly beyond said supporting member for engagement with the wall of the bore hole to enlarge the bore hole and cut the transverse shoulder therein upon lateral outward expansion of said supporting members and cutters.

Claim 5

In a rotary drill bit as defined in claim 1; and detachable means mounting each roller cutter individually on the lower end of its supporting member.

Claim 6

In a rotary drill bit as defined in claim 1; said cutters longitudinally spaced from each other being rotatable about axes lying in a plane radial of the longitudinal axis of said body; one of said cutters carried by each supporting member extending laterally outwardly beyond said supporting member for engagement with the wall of the bore hole to cut the transverse shoulder therein upon lateral outward expansion of said supporting members and cutters.

Claim 7

In a rotary drill bit as defined in claim 1; said cutters laterally spaced from each other being rotatable about axes lying in a plane radial of the longitudinal axis of said body; one of said cutters carried by each supporting member extending laterally outwardly beyond said supporting member for engagement with the wall of the bore hole to enlarge the bore hole and cut the transverse shoulder therein upon lateral outward expansion of said supporting members and cutters; and detachable means mounting each roller cutter individually on the lower end of its supporting member.

Claim 8

In a rotary drill bit as defined in claim 1; a first plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a first plane radial of the longitudinal axis of said body; a second plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a second plane radial of the longitudinal axis of said body; said first and second planes being arcuately displaced from each other.

Claim 9

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body; a plurality of roller cutters carried by each supporting member for operation upon a transverse formation shoulder in the bore hole; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; and means for expanding said supporting members and cutters carried thereby laterally outwardly of said body for operation of said cutters upon the transverse formation shoulder; a first plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a first plane radial of the longitudinal axis of said body; a second plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a second plane radial of the longitudinal axis of said body; said first and second planes being arcuately displaced from each other, the lateral spacing between said first plurality of cutters being substantially greater than the lateral spacing between said second plurality of cutters.

Claim 10

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body; a plurality of roller cutters carried by each supporting member for operation upon a transverse formation shoulder in the bore hole; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; and means for expanding said supporting members and cutters carried thereby laterally outwardly of said body for operation of said cutters upon the transverse formation shoulder; a first plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a first plane radial of the longitudinal axis of said body; a second plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a second plane radial of the longitudinal axis of said body; said first and second planes being arcuately displaced from each other, the lateral spacing between said first plurality of cutters being substantially greater than the lateral spacing between said second plurality of cutters.

Claim 11

In a rotary drill bit to be lowered in a bore hole: a main body; means for rotating said body; circumferentially spaced supporting members pivotally mounted at their upper portions on said body for expansion laterally outwardly of said body and for rotation with said body; each supporting member having a lower mounting base portion extending transversely in opposite directions substantially beyond the sides of the portion of the supporting member thereabove; a plurality of roller cutters for each supporting member for enlarging the diameter of the bore hole and thereby produce a transverse shoulder therein and for operation upon the transverse formation shoulder; a head for each cutter; means secured to each head rotatably mounting a cutter; and means for securing each head to the bottom of said base portion with its roller cutter below said base portion; said heads and cutters being so carried by said base portion that some of the cutters are circumferentially spaced from each other, some of the cutters being laterally spaced from each other; and means operable while said main body, supporting members and cutters are being rotated by said rotating means for expanding said supporting members and cutters laterally outwardly of said body for enlarging the bore hole diameter and for operation of said cutters upon the transverse formation shoulder in the bore hole.

Claim 12

In a rotary drill bit to be lowered in a bore hole: a main body; means for rotating said body; circumferentially spaced supporting members pivotally mounted at their upper portions on said body for expansion laterally outwardly of said body and for rotation with said body; each supporting member having a lower mounting base portion extending transversely in opposite directions substantially beyond the sides of the portion of the supporting member thereabove; a plurality of roller cutters for each supporting member for enlarging the diameter of the bore hole and thereby produce a transverse shoulder therein and for operation upon the transverse formation shoulder; a head for each cutter; means secured to each head rotatably mounting a cutter; and means for securing each head to the bottom of said base portion with its roller cutter below said base portion; said heads and cutters being so carried by said base portion that some of the cutters are circumferentially spaced from each other, some of the cutters being laterally spaced from each other; and means operable while said main body, supporting members and cutters are being rotated by said rotating means for expanding said supporting members and cutters laterally outwardly of said body for enlarging the bore hole diameter and for operation of said cutters upon the transverse formation shoulder in the bore hole.

Claim 13

In a rotary drill bit as defined in claim 9; a first plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a first plane radial of the longitudinal axis of said body; a second plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a second plane radial of the loNgitudinal axis of said body; said first and second planes being arcuately displaced from each other.

Claim 14

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members pivotally mounted at their upper portions on said body for expansion laterally outwardly of said body; each supporting member having a lower mounting base portion extending transversely in opposite directions substantially beyond the sides of the portion of the supporting member thereabove; a plurality of roller cutters for each supporting member; a head for each cutter; means secured to each head rotatably mounting a cutter; and means for securing each head to the bottom of said base portion with its roller cutter below said base portion; said heads and cutters being so carried by said base portion that some of the cutters are circumferentially spaced from each other, some of the cutters being laterally spaced from each other; and means for expanding said supporting members and cutters laterally outwardly of said body for operation of said cutters upon a transverse formation shoulder in the bore hole; a first plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a first plane radial of the longitudinal axis of said body; a second plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a second plane radial of the longitudinal axis of said body; said first and second planes being arcuately displaced from each other; the lateral spacing between said first plurality of cutters being substantially greater than the lateral spacing between said second plurality of cutters.

Claim 15

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members pivotally mounted at their upper portions on said body for expansion laterally outwardly of said body; each supporting member having a lower mounting base portion extending transversely in opposite directions substantially beyond the sides of the portion of the supporting member thereabove; a plurality of roller cutters for each supporting member; a head for each cutter; means secured to each head rotatably mounting a cutter; and means for securing each head to the bottom of said base portion with its roller cutter below said base portion; said heads and cutters being so carried by said base portion that some of the cutters are circumferentially spaced from each other, some of the cutters being laterally spaced from each other; and means for expanding said supporting members and cutters laterally outwardly of said body for operation of said cutters upon a transverse formation shoulder in the bore hole; a first plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a first plane radial of the longitudinal axis of said body; a second plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a second plane radial of the longitudinal axis of said body; said first and second planes being arcuately displaced from each other; the lateral spacing between said first plurality of cutters being substantially greater than the lateral spacing between said second plurality of cutters.

Claim 16

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body; a plurality of roller cutters carried by each supporting member for operation upon a transverse formation shoulder in the bore hole; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and supporting members; and means for relatively shifting said body, supporting members and roller cutters longitudinally with respect to said mandrel while said mandrel and body are rotated by the drill string to cause said expander means to expand said supporting members and cutters laterally outwardly of said body for some of said cutters to enlarge the diameter of the bore hole and for said cutters to operate upon the transverse formation shoulder.

Claim 17

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body; a plurality of roller cutters carried by each supporting member for operation upon a transverse formation shoulder in the bore hole; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and supporting members; and means for relatively shifting said body, supporting members and roller cutters longitudinally with respect to said mandrel while said mandrel and body are rotated by the drill string to cause said expander means to expand said supporting members and cutters laterally outwardly of said body for some of said cutters to enlarge the diameter of the bore hole and for said cutters to operate upon the transverse formation shoulder.

Claim 18

In a rotary drill bit as defined in claim 12; a first plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a first plane radial of the longitudinal axis of said body; a second plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a second plane radial of the longitudinal axis of said body; said first and second planes being arcuately displaced from each other.

Claim 19

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body; a plurality of roller cutters carried by each supporting member for operation upon a transverse formation shoulder in the bore hole; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling toRque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and supporting members; and means for relatively shifting said body, supporting members and roller cutters longitudinally with respect to said mandrel to cause said expander means to expand said supporting members and cutters laterally outwardly of said body for operation of said cutters upon the transverse formation shoulder; a first plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a first plane radial of the longitudinal axis of said body; a second plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a second plane radial of the longitudinal axis of said body; said first and second planes being arcuately displaced from each other; the lateral spacing between said first plurality of cutters being substantially greater than the lateral spacing between said second plurality of cutters.

Claim 20

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body; a plurality of roller cutters carried by each supporting member for operation upon a transverse formation shoulder in the bore hole; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling toRque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and supporting members; and means for relatively shifting said body, supporting members and roller cutters longitudinally with respect to said mandrel to cause said expander means to expand said supporting members and cutters laterally outwardly of said body for operation of said cutters upon the transverse formation shoulder; a first plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a first plane radial of the longitudinal axis of said body; a second plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a second plane radial of the longitudinal axis of said body; said first and second planes being arcuately displaced from each other; the lateral spacing between said first plurality of cutters being substantially greater than the lateral spacing between said second plurality of cutters.

Claim 21

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members pivotally mounted at their upper portions on said body for expansion laterally outwardly of said body; each supporting member having a lower mounting base portion extending circumferentially in opposite directions substantially beyond the sides of the portion of the supporting member thereabove; a plurality of roller cutters for each supporting member; a head for each cutter; means secured to each head rotatably mounting a cutter; means for securing each head to the bottom of said base portion with its roller cutter below said base portion; said heads and cutters being so carried by said base portion that some of the cutters are circumferentially spaced from each other, some of the cutters being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and supporting member; and means for relatively shifting said body, supporting members and roller cutters longitudinally with respect to said mandrel while said mandrel and body are rotated by the drill string to cause said expander means to expand said supporting members and cutters laterally outwardly of said body for some of said cutters to enlarge the diameter of the bore hole and for said cutters to operate upon a transverse formation shoulder in the bore hole.

Claim 22

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members pivotally mounted at their upper portions on said body for expansion laterally outwardly of said body; each supporting member having a lower mounting base portion extending circumferentially in opposite directions substantially beyond the sides of the portion of the supporting member thereabove; a plurality of roller cutters for each supporting member; a head for each cutter; means secured to each head rotatably mounting a cutter; means for securing each head to the bottom of said base portion with its roller cutter below said base portion; said heads and cutters being so carried by said base portion that some of the cutters are circumferentially spaced from each other, some of the cutters being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and supporting member; and means for relatively shifting said body, supporting members and roller cutters longitudinally with respect to said mandrel while said mandrel and body are rotated by the drill string to cause said expander means to expand said supporting members and cutters laterally outwardly of said body for some of said cutters to enlarge the diameter of the bore hole and for said cutters to operate upon a transverse formation shoulder in the bore hole.

Claim 23

In a rotary drill bit as defined in claim 15; a first plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a first plane radial of the longitudinal axis of said body; a second plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a second plane radial of the longitudinal axis of said body; said first and second planes being arcuately displaced from each other.

Claim 24

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members pivotally mounted at their upper portions on said body for expansion laterally outwardly of said body; each supporting member having a lower mounting base portion extending circumferentially in opposite directions substantially beyond the sides of the portion of the supporting member thereabove; a plurality of roller cutters for each supporting member; a head for each cutter; means secured to each head rotatably mounting a cutter; means for securing each head to the bottom of said base portion with its roller cutter below said base portion; said heads and cutters being so carried by said base portion that some of the cutters are circumferentially spaced from each other, some of the cutters being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transMitted from said mandrel to said body; coengageable expander means on said mandrel and supporting member; and means for relatively shifting said body, supporting members and roller cutters longitudinally with respect to said mandrel to cause said expander means to expand said supporting members and cutters laterally outwardly of said body for operation of said cutters upon a transverse formation shoulder in the bore hole; a first plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a first plane radial of the longitudinal axis of said body; a second plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a second plane radial of the longitudinal axis of said body; said first and second planes being arcuately displaced from each other; the lateral spacing between said first plurality of cutters being substantially greater than the lateral spacing between said second plurality of cutters.

Claim 25

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members pivotally mounted at their upper portions on said body for expansion laterally outwardly of said body; each supporting member having a lower mounting base portion extending circumferentially in opposite directions substantially beyond the sides of the portion of the supporting member thereabove; a plurality of roller cutters for each supporting member; a head for each cutter; means secured to each head rotatably mounting a cutter; means for securing each head to the bottom of said base portion with its roller cutter below said base portion; said heads and cutters being so carried by said base portion that some of the cutters are circumferentially spaced from each other, some of the cutters being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transMitted from said mandrel to said body; coengageable expander means on said mandrel and supporting member; and means for relatively shifting said body, supporting members and roller cutters longitudinally with respect to said mandrel to cause said expander means to expand said supporting members and cutters laterally outwardly of said body for operation of said cutters upon a transverse formation shoulder in the bore hole; a first plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a first plane radial of the longitudinal axis of said body; a second plurality of said cutters carried by each supporting member being laterally spaced from each other and rotatable about axes lying in a second plane radial of the longitudinal axis of said body; said first and second planes being arcuately displaced from each other; the lateral spacing between said first plurality of cutters being substantially greater than the lateral spacing between said second plurality of cutters.

Claim 26

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body; a plurality of roller cutters carried by each supporting member for operation upon a transverse shoulder in the bore hole; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and supporting members; said body having a cylinder portion above said expander means slidably and sealingly engaging said mandrel; said mandrel having a piston portion in said cylinder portion slidably and sealingly engaging said cylinder portion and dividing said cylinder portion into upper and lower fluid pressure chambers; and means for feeding fluid under pressure into one of said chambers to relatively shift said body, supporting members and roller cutters longitudinally with respect to said mandrel while said mandrel and body are rotated by the drill string to cause said expander means to expand said supporting members and cutters laterally outwardly of said body for some of said cutters to enlarge the diameter of the bore hole and for said cutters to operate upon the transverse formation shoulder.

Claim 27

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body; a plurality of roller cutters carried by each supporting member for operation upon a transverse shoulder in the bore hole; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and supporting members; said body having a cylinder portion above said expander means slidably and sealingly engaging said mandrel; said mandrel having a piston portion in said cylinder portion slidably and sealingly engaging said cylinder portion and dividing said cylinder portion into upper and lower fluid pressure chambers; and means for feeding fluid under pressure into one of said chambers to relatively shift said body, supporting members and roller cutters longitudinally with respect to said mandrel while said mandrel and body are rotated by the drill string to cause said expander means to expand said supporting members and cutters laterally outwardly of said body for some of said cutters to enlarge the diameter of the bore hole and for said cutters to operate upon the transverse formation shoulder.

Claim 28

In a rotary drill bit as defined in claim 18; said fluid feeding means comprising a conduit externally of said mandrel communicating with said one of said chambers.

Claim 29

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body; a plurality of roller cutters carried by each supporting member for operation upon a transverse shoulder in the bore hole; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and supporting members; said body having a cylinder portion above said expander means slidably and sealingly engaging said mandrel; said mandrel having a piston portion in said cylinder portion slidably and sealingly engaging said cylinder portion and dividing said cylinder portion into upper and lower fluid pressure chambers; and means for feeding fluid under pressure into one of said chambers to relatively shift said body, supporting members and roller cutters longitudinally with respect to said mandrel to cause said expander means to expand said supporting members and cutters laterally outwardly of said body for operation of Said cutters upon the transverse formation shoulder; a liquid confined in said other of said chambers initially preventing such relative longitudinal shifting; and means for releasing said liquid from said other of said chambers while the drill bit is in the bore hole.

Claim 30

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body; a plurality of roller cutters carried by each supporting member for operation upon a transverse shoulder in the bore hole; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and supporting members; said body having a cylinder portion above said expander means slidably and sealingly engaging said mandrel; said mandrel having a piston portion in said cylinder portion slidably and sealingly engaging said cylinder portion and dividing said cylinder portion into upper and lower fluid pressure chambers; and means for feeding fluid under pressure into one of said chambers to relatively shift said body, supporting members and roller cutters longitudinally with respect to said mandrel to cause said expander means to expand said supporting members and cutters laterally outwardly of said body for operation of Said cutters upon the transverse formation shoulder; a liquid confined in said other of said chambers initially preventing such relative longitudinal shifting; and means for releasing said liquid from said other of said chambers while the drill bit is in the bore hole.

Claim 31

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body; a plurality of roller cutters carried by each supporting member for operation upon a transverse shoulder in the bore hole; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and supporting members; said body having a cylinder portion above said expander means slidably and sealingly engaging said mandrel; said mandrel having a piston portion in said cylinder portion slidably and sealingly engaging said cylinder portion and dividing said cylinder portion into upper and lower fluid pressure chambers; and means for feeding fluid under pressure into one of said chambers to relatively shift said body, supporting members and roller cutters longitudinally with respect to said mandrel to cause said expander means to expand said supporting members and cutters laterally outwardly of said body for operation of said cutters upon the transverse formation shoulder; said one of said chambers being said upper chamber whereby fluid under pressure fed thereinto elevates said body, supporting members and cutters along said mandrel.

Claim 32

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body; a plurality of roller cutters carried by each supporting member for operation upon a transverse shoulder in the bore hole; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and supporting members; said body having a cylinder portion above said expander means slidably and sealingly engaging said mandrel; said mandrel having a piston portion in said cylinder portion slidably and sealingly engaging said cylinder portion and dividing said cylinder portion into upper and lower fluid pressure chambers; and means for feeding fluid under pressure into one of said chambers to relatively shift said body, supporting members and roller cutters longitudinally with respect to said mandrel to cause said expander means to expand said supporting members and cutters laterally outwardly of said body for operation of said cutters upon the transverse formation shoulder; said one of said chambers being said upper chamber whereby fluid under pressure fed thereinto elevates said body, supporting members and cutters along said mandrel.

Claim 33

In a rotary drill bit as defined in claim 21; a liquid confined in said lower chamber initially preventing elevation of said body, supporting members and cutters along said mandrel; and means for releasing said liquid from said lower chamber while the drill bit is in the bore hole.

Claim 34

In a rotary drill bit as defined in claim 21; a liquid confined in said lower chamber initially preventing elevation of said body, supporting members and cutters along said mandrel; and means for releasing said liquid from said lower chamber while the drill bit is in the bore hole; said fluid feeding means comprising a conduit externally of said mandrel communicating with said upper chamber.

Claim 35

In a rotary drill bit as defined in claim 21; a liquid confined in said lower chamber initially preventing elevation of said body, supporting members and cutters along said mandrel; and means for releasing said liquid from said lower chamber while the drill bit is in the bore hole; said fluid feeding means comprising a conduit externally of said mandrel communicating with said upper chamber; and means for feeding compressed air into said mandrel to aerate the liquid column therein and in the drill string thereabove, whereby liquid in the well bore externally of the drill bit flushes cuttings into the mandrel for upward passage through the mandrel and drill string.

Claim 36

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body; a plurality of roller cutters carried by each supporting member for operation upon a transverse formation shoulder in the bore hole; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and supporting members; and means for relatively shifting said body, supporting members and roller cutters longitudinally with respect to said mandrel to cAuse said expander means to expand said supporting members and cutters laterally outwardly of said body for operation of said cutters upon the transverse formation shoulder; and means for feeding compressed air into said mandrel to aerate the liquid column therein and in the drill string thereabove, whereby liquid in the well bore externally of the drill bit flushes cuttings into the mandrel for upward passage through the mandrel and drill string.

Claim 37

In a rotary drill bit to be lowered in a bore hole: a main body; circumferentially spaced supporting members mounted on said body for expansion laterally outwardly of said body; a plurality of roller cutters carried by each supporting member for operation upon a transverse formation shoulder in the bore hole; some of the cutters carried by each supporting member being circumferentially spaced from each other, some of the cutters carried by each supporting member being laterally spaced from each other; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and supporting members; and means for relatively shifting said body, supporting members and roller cutters longitudinally with respect to said mandrel to cAuse said expander means to expand said supporting members and cutters laterally outwardly of said body for operation of said cutters upon the transverse formation shoulder; and means for feeding compressed air into said mandrel to aerate the liquid column therein and in the drill string thereabove, whereby liquid in the well bore externally of the drill bit flushes cuttings into the mandrel for upward passage through the mandrel and drill string.

Claim 38

In a rotary drill bit to be lowered in a bore hole: a main body; cutter means mounted on said body for expansion laterally outwardly of said body; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and cutter means; said body having a cylinder portion above said expander means slidably and sealingly engaging said mandrel; said mandrel having a piston portion in said cylinder portion slidably and sealingly engaging said cylinder portion and dividing said cylinder portion into upper and lower fluid pressure chambers; means for feeding fluid under pressure into one of said chambers to relatively shift said body and cutter means longitudinally with respect to said mandrel to cause said expander means to expand said cutter means laterally outwardly of said body; a liquid confined in said other of said chambers initially preventing such relative longitudinal shifting; and means for releasing said liquid from said other of said chambers while the drill bit is in the bore hole.

Claim 39

In a rotary drill bit to be lowered in a bore hole: a main body; cutter means mounted on said body for expansion laterally outwardly of said body; a mandrel connectible to a drill string and slidably splined to said body, whereby drilling torque is transmitted from said mandrel to said body; coengageable expander means on said mandrel and cutter means; said body having a cylinder portion above said expander means slidably and sealingly engaging said mandrel; said mandrel having a piston portion in said cylinder portion slidably and sealingly engaging said cylinder portion and dividing said cylinder portion into upper and lower fluid pressure chambers; means for feeding fluid under pressure into one of said chambers to relatively shift said body and cutter means longitudinally with respect to said mandrel to cause said expander means to expand said cutter means laterally outwardly of said body; a liquid confined in said other of said chambers initially preventing such relative longitudinal shifting; and means for releasing said liquid from said other of said chambers while the drill bit is in the bore hole.

Claim 40

In a rotary drill bit as defined in claim 26; said one of said chambers being said upper chamber, whereby fluid under pressure fed thereinto elevates said body and cutter means along said mandrel; said other of said chamber being said lower chamber in which the liquid is confined.

Claim 41

In a rotary drill bit as defined in claim 26; said one of said chambers being said upper chamber, whereby fluid under pressure fed thereinto elevates said body and cutter means along said mandrel; said other of said chamber being said lower chamber in which the liquid is confined; said fluid feeding means comprising a conduit externally of said mandrel communicating with said upper chamber.

Claim 42

In a rotary drill bit as defined in claim 26; said one of said chambers being said upper chamber, whereby fluid under pressure fed thereinto elevates said body and cutter means along said mandrel; said other of said chamber being said lower chamber in which the liquid is confined; said fluid feeding means comprising a conduit externally of said mandrel communicating with said upper chamber; and means for feeding compressed air into said mandrel to aerate the liquid column therein and in the drill string thereabove, whereby liquid in the well bore externally of the drill bit flushes cuttings into the mandrel for upward passage through the mandrel and drill string.