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
  • E21B10/44—Bits with helical conveying portion, e.g. screw type bits; Augers with leading portion or with detachable parts
  • E21B10/445—Bits with helical conveying portion, e.g. screw type bits; Augers with leading portion or with detachable parts percussion type, e.g. for masonry
• • 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
  • E21B10/58—Chisel-type inserts

Definitions

• Carbide-tipped masonry drills are fairly well known. A bit manufactured of tungsten carbide or other hardened material is inserted into a slot in the working end of a metallic shank, held in place utilizing a paste or other material which is replaced when the carbide insert is brazed within the slot. This practice, however, is very inaccurate in that the carbide insert is not oriented within the slot accurately and also prevents a clean braze.
• U.S. Patent No. 3,447,616 teaches a drill having a detachable blade mounted on the end thereof in a slot extending transversely to the body of the drill . The blade is constructed with a hub having portions on opposite faces of the blade which fits into an opening formed into said slot so that the blade is oriented properly within the slot.
• U.S. Patent No. 4,314,616 teaches a die-cast masonry drill with leading hard insert.
• the hardened insert is placed into the dies within which the drill body is to be cast.
• the drill body is cast in place around the insert with the molten material substantially surrounding the insert as well as interlocking means located on said insert.
• the insert is held into place within said slot by the contraction of the metal of the drill body due to differences in rates of thermal expansion.
• the present invention comprises an elongated cylindrical drill body having at one distal end a transverse slot extending thereacross and a shank at the opposite distal end, said drill body having at least one spiral groove formed along its exterior surface from said transverse slot to said shank; a drill bit insert brazed within said transverse slot, said insert having: a bottom surface; a first and second parallel planar surface; a first and second side face connecting said first and second planar surfaces; a leading crown tip forming a first and a second upper surface extending downward from said crown tip to said first and second side faces; a first and a second cutting edge formed along opposite sides of said first and second upper surfaces; at least one projection extending vertically on each of said first and said second planar surface; and, a braze fill in the joint between said insert and said transverse slot.
• Fig. 5 is a perspective view of the cylindrical drill body of the present invention.
• Fig. 8 is a modification of Figure 2 with projections extending the full length of each planar surface.
• the cylindrical drill body 11 has at its working end a transverse slot 26 shown in Fig. 5.
• the slot 26 is formed by milling and allows for the insertion of drill bit insert 20.
• the transverse slot 26 is of such width as to allow for a snug fit of the drill bit insert 20 into slot 26.
• Slot 26 has smooth channel side walls 27 and 28 so the drill bit insert 20 may readily slide into slot 26.
• Axial drill body 11 and shank 17 is constructed of solid material, such as steel, which is malleable enough to allow for the proper insertion of the hardened drill bit insert 20 into slot 26 while still providing enough resistance to firmly engage said insert.
• Drill bit insert 20 is pressed into slot 26 using a press, said force sufficient enough to insert the carbide insert fully into the slot and allow the rib or projection members 21 and 22, shown in Figure 2A, to engage side walls 27 and 28 of the transverse slot 26.
• bottom surface 12 of drill bit insert 20 may have slightly bevelled edges. Bevelling of the edges allows for easy insertion of drill bit insert 20 into slot 26.
• the bottom surface 12 of the drill bit may be bevelled when transverse slot 26 has a base portion 26a which does not have a curvature as shown in Fig. 5. If the slot base 26a is perpendicular to slot walls 27 and 28, bevelled base 12 allows the braze material to flow between the ribs, when two ribs are utilized, and prevents air pockets from forming thereby causing a solid braze fill for the entire length of the rib members. When a curved base 26a is utilized as shown in Fig. 5, no bevelling of the base is required.
• the masonry drill bit shown is designed to be a clockwise rotating drill bit, from the perspective of the shank end, with the projections or ribs formed on the trailing face opposite the leading cutting edge.
• leading cutting edge 32 has no ribs or projections formed therebelow on half of the planar surface 30 directly below the cutting edge 32.
• -Si- There are however, formed on planar surface 30, ribs or projections formed on the other half portion of surface 30 which trails cutting edge 31.
• This same design is mirrored on planar surface 29, where ribs 23 and 24 are formed below upper surface 13 but not below upper surface 14, as shown in Fig. 2A.
• the projections have a width of preferably about 0.03 inch on a one-quarter inch drill bit and 0.06 inch on a one- half inch drill bit thus providing sufficient contact surface against transverse slot side walls 27 and 28, of Fig. 5, to secure the drill bit within the slot.
• the projections when the drill bit insert is inserted within slot 26, slightly deform the side walls 27 and 28 causing corresponding indentions to be formed on the side walls. The deformation however is slight and the insert 20 must still be brazed within the slot for proper securing.
• the width and outward extension of the projections must be sufficient to allow braze material, preferably a copper silver alloy, to flow into transverse slot 26 and surround the drill bit effectively brazing the drill bit 20 into the working end of the axial drill body 11.
• braze material preferably a copper silver alloy
• a clearance of .003 inch is provided for the brazing material to flow into the openings created thereby providing for proper braze coverage and keeping shrinkage porosity to a minimum.
• the difference between the clearance provided between insert 20 and slot walls 27 and 28 and the actual outward distance of projections 21 and 24 (0.003 inch compared to 0.008 inch) is caused by the slight deformation of the said walls caused when the insert is inserted into the slot.
• Braze fill thickness preferentially fills the entire gap between the insert 20 and slot walls 27 and 28 and below the inserted carbide insert within the channel or slot, from a maximum of .008 inch to a minimum of .003 inch.
• the hardened drill bit insert 20 of the present invention having projections 21, 22, 23, and 24, is forcibly inserted into channelled slot 26 located at the working end of axial drill body 11.
• the projections cause transverse slot side walls 27 and 28 to slightly deform laterally and thereby hold the insert into place by tension.
• the drill bit insert is brazed within transverse slot using a copper alloy braze material, said material of sufficient quality and fluidity to flow around and below the drill bit insert and secure said insert within said slot.
• the braze material must be solid enough to allow for repeated use of the masonry drill bit without cracking or wear of the braze thus causing the drill bit insert 20 to come loose from slot 26.
• the brazed joint formed exhibits excellent fill and thickness.
• joint thickness for the braze of the present invention is kept below .01 inch thus providing for good braze flow and reduction in shrinkage porosity.

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

Applications Claiming Priority (5)

Publications (1)

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• 1996
  • 1996-06-04 EP EP96917192A patent/EP0853521A1/en not_active Withdrawn
  • 1996-06-04 WO PCT/US1996/008927 patent/WO1996040461A1/en not_active Ceased
  • 1996-06-04 NZ NZ309636A patent/NZ309636A/en unknown
  • 1996-06-04 CA CA 2221617 patent/CA2221617A1/en not_active Abandoned
  • 1996-06-04 JP JP9501378A patent/JPH11512976A/ja active Pending
  • 1996-06-04 AU AU59854/96A patent/AU695791B2/en not_active Ceased
  • 1996-06-04 BR BR9609054A patent/BR9609054A/pt not_active Application Discontinuation

Non-Patent Citations (1)

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