US20090184564A1 - Pcd percussion drill bit - Google Patents

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Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B10/00—Drill bits
  • E21B10/36—Percussion drill bits
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B10/00—Drill bits
  • E21B10/46—Drill bits characterised by wear resisting parts, e.g. diamond inserts
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
  • E21B17/10—Wear protectors; Centralising devices, e.g. stabilisers
  • E21B17/1092—Gauge section of drill bits

Definitions

• the present invention relates generally to rock drill bits, and more particularly to rotary percussion drill bits having PCD inserts constructed and arranged for improved performance and duration of the drill bit in rock crushing and boring operations.
• PCD polycrystalline diamond
• WC tungsten carbide
• HCD high density ceramic
• Percussion drilling is typically carried out by driving the drill bit into the rock work surface in a reciprocating manner at a striking or impact force of about 300-500 ft/lbs and also rotated at about 250-300 rpm during drilling.
• the impact frequency is about six (6) blows for each one (1) degree of rotation.
• pneumatic power this will equate to about 2100-2200 blows per minute; and a much higher impact frequency of 7000 to 8000 striking blows if using hydraulic power.
• rotary percussion drilling is carried out by reciprocatingly driving the drill bit to crack and crush the rock and rotating the bit to cut away and remove the crushed rock from the developing bore hole.
• a percussion drill bit for drilling bore holes in hard rock which comprises a steel body having a working front head portion and a rearward shank portion for connection to an impact driving force, the head portion having a front facing central zone and plural side wing zones extending radially from the central zone and spaced apart at the outer circumferential edges thereof by grooves in the outer wall of the front head portion, first gauge-cutting PCD inserts are secured in at least two of said side wing zones of the steel body and are constructed and arranged to extend forwardly and outwardly at an angle to the axis of the bit and be operable for forming the bore hole, at least one second PCD insert is non-axially secured in the central zone and projects forwardly of the first PCD inserts and is operable for impact at the core area of the bore hole to pilot the boring effort of the first PCD inserts.
• the head portion of the steel body is armored with a hard cladding material tougher than the steel body to thereby reduce outer body wear at the side wing zones and to thereby prolong the PCD insert integrity and provide a substantially longer drill bit life.
• FIG. 1 is a perspective view of a first embodiment of a percussion drill bit according to the invention
• FIG. 2 is a side elevational view of the first embodiment, partly broken away to show a PCD insert socket;
• FIG. 3 is another side elevational view, as rotated 90° from the FIG. 2 position, and broken away to show flushing fluid distribution;
• FIG. 4 is a top plan view of the first embodiment
• FIG. 5 is a cross-sectional view taken substantially along line 5 - 5 of FIG. 4 ;
• FIG. 6 is a greatly enlarged diagrammatic and fragmentary view illustrating the geometry of the working head portion of the first embodiment
• FIG. 7 is a side elevational view of a second embodiment of the invention with portions broken away to show side wall cladding.
• FIG. 8 is a section similar to FIG. 5 and showing a metal cladding of the head portion front face.
• FIGS. 1-6 show a first embodiment of a percussion rock drill bit of the present invention, generally designated 10 .
• the drill bit includes a steel body 12 having a working head portion 14 and a rearward shank portion 16 with a common central axis “a-a” ( FIG. 6 ).
• the shank portion 16 has a central bore 20 with an internal rope thread 21 for threaded connection to a hammer driven drill string apparatus (not shown).
• the central bore 20 connects to three flushing channels 22 constructed and arranged to direct flushing and cooling fluid through the head portion 14 and around the front facing surface 23 thereof.
• the front surface is generally perpendicular to the central axis “a-a” (as shown by reference line “b-b” in FIG. 6 ).
• the circumference of the front facing head portion area is larger than the circumference of the shank portion 16 whereby the outer side wall 24 of the head portion 14 tapers inwardly from the front circumference down to the shank portion 16 about 8° (as shown in FIG. 6 ). It will be understood that the taper may be other than 8° within the scope of the present invention.
• the head portion 14 is provided with three vertical and elongate grooves or channels 25 that are symmetrically spaced around the circumference and extend vertically toward the shank portion 16 and which define therebetween three symmetrically spaced wing zones 27 .
• wedge-shaped grooves 25 are constructed to receive the flushing fluid ported from the passageways 22 and channel it toward the working front face ( 23 ) of the head portion 14 as well as providing a flow path for removing the rock chippings (not shown) as the bore hole is being formed.
• the head portion 14 is provided with three first or primary gauge-cutting PCD inserts 30 symmetrically spaced from each other and secured in primary sockets 38 into the wing zones 27 .
• the head portion 14 also is provided with second or secondary PCD inserts 31 constructed and arranged as core-cutters in a central zone 33 of the front face ( 23 ). Three such second PCD inserts are shown in the preferred embodiment of FIGS. 1-6 , and these are asymmetrically and non-axially arranged in secondary sockets 45 in the central zone 33 at the front of the head portion 14 .
• the circumferential area 35 of the front face of the tool extending radially outwardly from around the central zone 33 is sloped axially rearwardly (or downwardly in the drawings) at an angle of about 15° to 35°, and preferably about 22° to 26° (see “h” in FIG. 6 ).
• the head portion 14 is provided with the three primary sockets 37 formed in each of the wing zones 27 and extending into the steel body 12 on axes substantially perpendicular to the slope of the wing zone surface 35 , and these sockets 37 are slightly smaller (i.e., about 0.002 inch) than the base diameter of the first PCD inserts 30 whereby the pressfit of the inserts under about 5 tons of force provides a secure seating of the inserts 30 in the sockets 37 through it will be noted that the first gauge-cutting PCD inserts 30 in the first embodiment are larger than the second core-breaking PCD inserts 31 .
• the first PCD inserts 30 will typically have a main body of tungsten carbide with a cylindrical base section 42 and a domed working end 39 capped with a parabolic or bullet-shaped domed crown 40 of PCD material (see FIG. 5 ).
• the base section 42 When assembled the base section 42 is deeply seated in the socket 37 of each wing zone 35 and the cylindrical wall extends beyond the sloping head portion surface about 1/16 inch (at 41 ) so that the gauge-cutting PCD crown caps 40 are precisely set at a predetermined position (see “e-e” of FIG. 6 ) in front of the front face “b-b” of the head portion 14 .
• the secondary core-cutting PCD inserts 31 have essentially the same configuration as the first PCD inserts 30 , although they have a smaller diameter in the preferred first embodiment.
• the coring PCD inserts 31 are set in sockets 45 formed in the central zone 33 of the front face ( 23 ) and are non-symmetrically and non-axially arranged to impact against different adjacent core areas as the bore hole is being formed.
• the secondary PCD inserts 31 are also set to extend forwardly of the front face ( 23 ), but in an axial direction and to a precise spaced distance (plane “d-d” in FIG. 6 ) that is beyond the plane “e-e” of the gauge-cutting PCD inserts 30 . As shown in FIGS.
• the central zone 33 may be formed as an elevated or raised platform having a side wall 43 .
• the core-cutting PCD inserts 31 initiate or pilot the bore hole formation by breaking a smaller central core area thereof followed by the gauge-cutting action of the first PCD inserts 30 to complete the full bore hole drilling.
• the flushing fluid carries away the loose chippings as the hole is formed as well as cools the diamond inserts 30 , 31 to prevent overheating thereof. It will be understood that a wide variance of non-symmetrical coring insert arrangements can be made, and that having a side wall 43 larger diameter inserts 31 may be used on larger sized boring tools 10 .
• the geometry of the PCD inserts 30 and 31 in their sockets 37 and 45 can best be seen in FIGS. 5 and 6 .
• This geometry contributes to the integrity of the drill-bit, 110 and prolongs its useful life; and includes the angular relationship between the primary sockets 37 and the secondary sockets 45 and the depth thereof in the head portion 14 of the drill bit.
• the primary sockets 37 extend deepest (at 38 ) into the tool body 12 .
• the primary PCD inserts 30 extend outwardly at an angle to the axis of the drill bit but are arranged to produce a reaction force vector in an axial direction to push these primary inserts 30 more firmly into these sockets 37 .
• the secondary sockets 47 for the core-cutting PCD inserts 31 extend in an axial direction, but the bottoms 46 thereof are above the deeper primary sockets 37 and have no negative influence thereon. It may also be noted that the spherical cutting face of the respective PCD inserts distribute impact forces through the insert bodies, and further that the PCD layer itself does not wear out.
• the central zone 33 is shown as a circular area that is axially centered and is also shown as a raised platform having a side wall 43 of a minor dimension.
• the distance that the contact point of the core-breaking inserts extends forwardly of the crown of the gauge-cutting inserts is at least as large as the platform elevation.
• the central zone 33 of the front face 23 may be a different shape such as a triangle, trapezoid or pentagon that will help to define selected non-asymmetrical locations for orientation of multiple cone-cutting inserts 31 without interference with the seating sites (primary sockets 37 ) for the gauge-cutting inserts 30 .
• the raised platform 43 facilitates the location of secondary sockets in an axial direction away from the angularly related sockets 37 for the outer PCD inserts but without direct interference or compromising their structural integrity or the press-fit strength thereof.
• the steel body 112 at the head portion 114 of the drill bit 110 can be strengthened to better obviate erosion and wear of the head portion surface areas if reinforced by a harder metal cladding 150 .
• parts of the drill bit 110 corresponding to drill bit 10 will are given the same reference numeral, plus “100.”
• the use of exotic steels alloyed with chromium carbide or vanadium carbide would provide the toughest steel bodies for percussion tools, but at great expense.
• the present invention contemplates bonding a chromium or chromium alloy jacket 150 over the entire head portion 114 of the tool 110 .
• This chromium cladding layer 150 would have a thickness in the range of 0.005 to 0.010 inches and be tempered to a Rockwell hardness of at least 60 Rc and preferably 65-68 Rc.
• the sockets 137 and 145 for the first and second PCD inserts 130 and 131 will be formed after cladding process is completed.

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• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Mining & Mineral Resources (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Earth Drilling (AREA)

Abstract

Description

Claims (23)

Priority Applications (5)

Applications Claiming Priority (2)

Related Child Applications (1)

Publications (1)

Family

ID=40875893

Family Applications (1)

Country Status (1)

Cited By (14)

Citations (47)

• 2008
  • 2008-11-19 US US12/273,700 patent/US20090184564A1/en not_active Abandoned

Patent Citations (49)

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