Drill Bit for Percussive Penetration of Overburden (Patent No: 759838)

Inventor: Becker, Floyd W.

Location: Calgary

Comments: N/A

Description:
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A drill bit for impact drilling a substantially straight borehole in overburden earth materials comprising an annular body adapted to be carried at the lower end of a driving pipe, said body having a planar upper end face and an axial bore opening into said end face adapted for passing fragments upwardly therethrough into said pipe as said bit penetrates said earth materials, a plurality of circumferentially spaced integral teeth depending from said body parallel with the bit axis, said teeth having substantially constant radial width and tooth thickness dimensions along their length and terminating in chisel edges disposed radially about said axis, the outer ends of said tooth edges projecting beyond the plan outline of said upper end face to provide clearance for said bit body in said borehole and the inner ends of said tooth edges projecting inwardly of the plan projection of said axial bore to provide clearance for said fragments, the exterior wall of said body and the interior wall of said axial bore having an acute included angle as measured in a radial axial plane and intersecting in a cutting margin disposed between said upper end face and said tooth edges, said cutting margin comprising sectoral portions separated by intervening teeth, and lying in a common plane.

2. A drill bit as claimed in Claim 1 wherein said bit body has a cylindriform exterior wall and said axial bore narrows upwardly.

3. A drill bit as claimed in Claim 1 wherein said bit body has a cylindriform axial bore and said exterior wall is of conic form, and said teeth have fluid-guiding passages opening into said upper end face and opening into said axial bore adjacently above the plane of said cutting margin.

4. A drill bit as claimed in Claim 3 wherein said bore is vertically grooved between said end face and the inward openings of said fluid-guiding passages.

5. A drill bit for impact drilling a substantially straight borehole in gravel and conglomerates, comprising an annular body adapted to be carried at the end of a driving pipe, said body having an axial bore, an annular upper face, a lower cutting margin, and a conic outer surface widening upwardly and having a plurality of circumferentially spaced depending integral teeth projecting from said conic surface and extending parallel with the bit axis below said cutting margin, said teeth having a uniform radial width and constant tooth thickness along their length and terminating in chisel edges disposed radially about said axis, said edges extending beyond the outline of said upper face to provide clearance for said body in said borehole and extending into said axial bore to provide free upward passage of fragments, fluid-guiding passages in said teeth opening upwardly into said annular face and opening into said axial bore adjacent said tooth edges for jetting fluid into said bore above said cutting margin, and grooves extending between each inward passage opening and said annular face.

6. A drill bit as set forth in Claim 5 further including an integral cylindrical coaxial flange projecting from said annular upper face, said flange having an internal thread and having an external diameter less than the maximum transverse distance between the outer edges of said teeth to provide clearance for said flange in said borehole.

7. A drill bit as set forth in Claim 6 in combination with a detachable hollow fitting for separable attachment of said bit with said driving pipe, wherein said driving pipe comprises inner and outer pipes coaxially disposed to form therebetween an annular fluid-guiding chamber and a coaxial passage coextensive with said inner pipe, said outer pipe having a male pipe thread formed on a lower end and a female pipe thread formed on an upper end, said fitting comprising a tubular member having a thick wall, an upper portion formed with an internal pipe thread adapted for removable connection with said male pipe-threaded end of said driving pipe, said fitting having an end portion of reduced external diameter remote from said pipe-threaded upper portion threaded for engagement with said flange, and having an end face adjacent said reduced diameter portion disposed to bear against said planar upper face of said drill bit for transfer of impact energy thereto, said end face being formed with an annular recess, axial passages formed in said wall and opening into said recess in said end face, a peripheral groove formed in said internal pipe-threaded upper portion, and ports opening into said groove and communicating with said axial passages for connecting said annular chamber of said driving pipe with said fluid-guiding passages in said drill bit.