US20170234075A1 - Drilling tool - Google Patents

Drilling tool Download PDF

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Publication number
US20170234075A1
US20170234075A1 US15/501,975 US201515501975A US2017234075A1 US 20170234075 A1 US20170234075 A1 US 20170234075A1 US 201515501975 A US201515501975 A US 201515501975A US 2017234075 A1 US2017234075 A1 US 2017234075A1
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US
United States
Prior art keywords
bit
axis
tip
casing pipe
head
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US15/501,975
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English (en)
Inventor
Kazuyoshi Nakamura
Hiroki Takatsuki
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Materials Corp
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Mitsubishi Materials Corp
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Filing date
Publication date
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Assigned to MITSUBISHI MATERIALS CORPORATION reassignment MITSUBISHI MATERIALS CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: NAKAMURA, KAZUYOSHI, TAKATSUKI, HIROKI
Publication of US20170234075A1 publication Critical patent/US20170234075A1/en
Abandoned legal-status Critical Current

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    • 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
    • E21B10/26—Drill bits with leading portion, i.e. drill bits with a pilot cutter; Drill bits for enlarging the borehole, e.g. reamers
    • E21B10/32—Drill bits with leading portion, i.e. drill bits with a pilot cutter; Drill bits for enlarging the borehole, e.g. reamers with expansible cutting tools
    • 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
    • E21B10/26—Drill bits with leading portion, i.e. drill bits with a pilot cutter; Drill bits for enlarging the borehole, e.g. reamers
    • E21B10/32—Drill bits with leading portion, i.e. drill bits with a pilot cutter; Drill bits for enlarging the borehole, e.g. reamers with expansible cutting tools
    • E21B10/327—Drill bits with leading portion, i.e. drill bits with a pilot cutter; Drill bits for enlarging the borehole, e.g. reamers with expansible cutting tools the cutter being pivoted about a longitudinal axis
    • 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
    • E21B10/62—Drill bits characterised by parts, e.g. cutting elements, which are detachable or adjustable
    • E21B10/627—Drill bits characterised by parts, e.g. cutting elements, which are detachable or adjustable with plural detachable cutting elements

Definitions

  • the present invention relates to a so-called double pipe type drilling tool that performs drilling using a ring bit disposed on a tip side of a casing pipe, and a pilot bit inserted into the casing pipe.
  • PTL 1 suggests a drilling tool in which a ring bit is rotatably inserted into a tip part of a casing pipe with their inner and outer periphery surfaces being made to face each other; an inner bit is attached to a tip of a transmission member inserted into the casing pipe; striking force and impelling force are transmitted to the casing pipe and rotating force in addition thereto are transmitted to the ring bit via this inner bit so as to perform drilling; and after a borehole having a predetermined depth is formed, the ring bit be removed from the casing pipe and left in the borehole.
  • PTL 2 describes a so-called under-reaming bit in which an extendable bit is attached to an outer periphery of a tip part of a shank device rotated around an axis; a borehole having a predetermined internal diameter is formed while the extendable bit is positioned in a extending state and protrudes to a tip of a casing pipe during drilling; and after the end of the drilling, the extendable bit is shrunk and then is recovered with the shank device through the inside of the casing pipe.
  • the present invention has been made in view of such a background, and the objective thereof is to provide a borehole that can prevent degradation of drilling performance, occurrence of damage, and an increase in construction cost, in a case where a borehole with a greater internal diameter than the external diameter of a casing pipe is drilled.
  • the present invention provides a drilling tool including: a cylindrical casing pipe centered on an axis; an annular ring bit that is coaxially disposed on a tip side of the casing pipe and has a greater external diameter than the casing pipe; and a pilot bit that is inserted into an inner peripheral part of the ring bit through the inside of the casing pipe.
  • the pilot bit is rotatable around the axis and a bit head is provided at an outer peripheral part of a tip of the pilot bit.
  • the bit head is rotatable around a centerline eccentric from the axis, and is configured that when the pilot bit is rotated in a tool rotation direction during drilling, the bit head is extended such that a radius of the bit head from the axis is enlarged and thereby is supported by the pilot bit.
  • the ring bit is provided with: a part to be engaged that is configured to be engaged with the extended bit head in the tool rotation direction during drilling; and a first abutting part capable of abutting against the tip side of the extended bit head in a direction of the axis.
  • the bit head provided at the outer peripheral part of the tip of the pilot bit is extended during drilling, and the first abutting part provided at the ring bit abuts against the tip side of the extended bit head in the direction of the axis.
  • the ring bit can be prevented from coming off to the tip side thereof.
  • rotating force can be transmitted from the pilot bit via the bit head to the ring bit.
  • the external diameter of the ring bit is made to be greater than the external diameter of the casing pipe, via the extended bit head of which the radius from the axis is enlarged, sufficient rotating force can be transmitted to the ring bit, and drilling performance can be guaranteed.
  • the part to be engaged of the ring bit is engaged with the extended bit head in the tool rotation direction during drilling, in this way, the need for making an outer peripheral surface of a posterior end part of the ring bit face an inner peripheral surface of the casing pipe to allow the posterior end part to be rotatably inserted into the casing pipe is also eliminated. Therefore, the internal diameter of the ring bit can be increased, that is, a required material can be reduced by making the volume of the ring bit small.
  • construction cost can be prevented from increasing.
  • the radius of the extended bit head from the axis is not made as large as the radius of the borehole, a borehole with a large internal diameter can be formed by the ring bit, and damage or the like to the bit head can be prevented without exerting an excessive load.
  • the number of the drilling tip disposed on the annular ring bit that drills the outer peripheral side of the borehole can be relatively freely set, and it is also possible to prevent degradation of drilling performance resulting from shortage of chips.
  • a recessed portion that is recessed to an outer peripheral side is formed at the inner peripheral part of the ring bit, and the recessed portion serves as the part to be engaged, the volume of the ring bit can be further reduced, and construction cost can be further reduced.
  • a tip surface of the ring bit adjacent to the recessed portion may serve as the first abutting part, and a bottom surface that faces the tip side in the direction of the axis may be formed in the recessed portion so as to serve as the first abutting part.
  • a smaller-diameter part of which an internal diameter is one step smaller may be formed at an inner peripheral part of a tip of the casing pipe, and a second abutting part like a stepped part capable of abutting against the smaller-diameter part from a posterior end side in the direction of the axis may be formed at an outer peripheral part of a posterior end of the pilot bit so as to transmit the striking force and the impelling force.
  • the internal diameter of the ring bit equal to or greater than the internal diameter of the smaller-diameter part, the volume of the ring bit can be made small as described above, and construction cost can be reliably reduced.
  • the striking force and the impelling force may be directly transmitted to the ring bit from the pilot bit as in the drilling tool described in PTL 1.
  • the smaller-diameter part is formed at the inner peripheral part of the tip of the casing pipe and is made to be capable of abutting against the stepped part of the pilot bit as described above
  • a smaller-diameter part of which the internal diameter is further smaller than the smaller-diameter part of the casing pipe must be formed at the ring bit to abut against the pilot bit, and consequently, there is a concern that it becomes difficult to make the internal diameter of the ring bit small as described above to reduce construction cost.
  • the bit head by providing the bit head with a third abutting part which is capable of abutting against a surface of the ring bit that faces a posterior end side in the direction of the axis in a state where the bit head is extended, it becomes unnecessary to form a smaller-diameter part having a smaller internal diameter than the smaller-diameter part of the casing pipe in the ring bit, construction cost can be much more reliably reduced, and it is possible to reliably transmit the striking force and the impelling force from the pilot bit to the tip side in the direction of the axis to the ring bit via the third abutting part of the bit head.
  • the striking force and the impelling force can be transmitted to the outer peripheral side of the ring bit where drilling is performed.
  • the thickness of the ring bit in the direction of the axis can also be made small, and much more construction cost reduction can be achieved.
  • FIG. 1 is a cross-sectional view showing a state where a bit head is extended in one embodiment of the present invention.
  • FIG. 2 is an enlarged front view when the embodiment shown in FIG 1 in a state where the bit head is retracted is seen from a tip side in a direction of an axis (illustration of a casing pipe and a casing top is omitted).
  • FIG. 3 is an enlarged front view when the embodiment shown in FIG. 1 in a state where the bit head is extended is seen from the tip side in the direction of the axis (illustration of the casing pipe and the casing top is omitted).
  • FIG. 4 is an enlarged front view when the ring bit of the embodiment shown in FIG. 1 is seen from the tip side in the direction of the axis.
  • FIG. 5 is Z-Z sectional view in FIG. 4 .
  • FIGS. 1 to 5 show one embodiment of a drilling tool of the present invention.
  • a casing pipe 1 is formed in a cylindrical shape centered on an axis O using metallic materials, such as a steel material, and a casing top 1 A formed in a multi-stage cylindrical shape using metallic materials, such as a steel material, is attached to a tip part (left side in FIG. 1 ) of the casing pipe 1 .
  • the internal diameter thereof is a constant internal diameter that is one step smaller than the internal diameter of the casing pipe 1
  • the external diameter of a tip part is the same diameter as the casing pipe 1
  • the external diameter of a posterior end part is of a size such that the posterior end part can be inserted and fitted into the casing pipe 1 .
  • the posterior end part of the casing top 1 A is inserted and fitted into the casing pipe 1 from a tip side of the casing pipe 1 and then jointed by welding or the like, whereby the casing top 1 A is coaxially integrated with the casing pipe 1 .
  • a smaller-diameter part 1 B of which the internal diameter is one step smaller is formed at an inner peripheral part of the tip of the casing pipe 1 .
  • a posterior end surface of the smaller-diameter part 1 B is formed in the shape of a concave conical surface which is centered on the axis O and tilts toward an inner peripheral side so as to become slightly closer to the tip side.
  • a pilot bit 2 is inserted into the casing pipe 1 from a posterior end side thereof (right side in FIG. 1 ).
  • the pilot bit 2 is made of metallic materials such as a steel material and has an outer shape that is also formed in a multi-stage columnar shape, and a posterior end part thereof is made into a smaller-diameter shank part 2 A. Striking force directed to the tip side in the direction of the axis O is transmitted to the pilot bit 2 from a down-the-hole hammer H attached to the shank part 2 A.
  • a drill rod (not shown) is added if necessary and is coupled to the posterior end side of the down-the-hole hammer H, and a drill rod disposed at the most posterior end is attached to a drilling device.
  • the impelling force directed to the tip side in the direction of the axis O and the rotating force directed in a tool rotation direction T during drilling are transmitted to the pilot bit 2 from the drilling device via the drill rod and the down-the-hole hammer H.
  • the casing pipe 1 is also added to the posterior end side if necessary and is inserted into a borehole.
  • a stepped part of which the external diameter becomes a maximum is formed at an outer periphery of the pilot bit 2 at a position closer to the tip side than the shank part 2 A, and serves as a second abutting part 2 B of the present embodiment.
  • the external diameter of the second abutting part 2 B is slightly smaller than the internal diameter of the casing pipe 1 and greater than the internal diameter of the smaller-diameter part 1 B formed by the casing top 1 A.
  • a tip surface of the second abutting part 2 B is formed in the shape of a convex conical surface which tilts toward the inner peripheral side so as to become slightly closer to the tip side, and the tilt angle thereof is equal to the tilt angle of the posterior end surface of the smaller-diameter part 1 B that forms the concave conical surface shape.
  • the pilot bit 2 is coaxial with the casing pipe 1 and the casing top 1 A movable integrally with the casing pipe 1 and the casing top 1 A to the tip side in the direction of the axis O, and rotatable around the axis O relative to the casing pipe 1 and the casing top 1 A, in a place where the pilot bit 2 is inserted into the casing pipe 1 from the posterior end side thereof and the second abutting part 2 B abuts against the smaller-diameter part 1 B.
  • the external diameter of the pilot bit 2 at a position closer to the tip side than the second abutting part 2 B is a constant external diameter slightly smaller than the internal diameter of the smaller-diameter part 1 B formed by the casing top 1 A, and thus a tip part of the pilot bit 2 is formed so as to protrude greatly from the tip of the casing top 1 A in a state where the second abutting part 2 B abuts against the smaller-diameter part 1 B.
  • a housing recess 3 is formed at an outer periphery of the tip part of the pilot bit 2 protruding from the tip of the casing top 1 A so as to be located closer to the tip side than the casing top 1 A.
  • the housing recess 3 includes: a bottom surface 3 A that is located closer to the tip side than the casing top 1 A, faces the tip side, and is perpendicular to the axis O; and a wall surface 3 B that extends to tip side in parallel with the axis O from an inner peripheral edge of the bottom surface 3 A and reaches a tip surface of the pilot bit 2 .
  • the housing recess 3 is formed so as to be open to an outer peripheral surface and a tip surface of the tip part of the pilot bit 2 .
  • a plurality of (three) such housing recesses 3 having the same form and the same size are formed at equal intervals in a circumferential direction.
  • a wall surface 3 B of each housing recess 3 includes: a first wall part 3 a that is a plane facing an outer peripheral side of the pilot bit 2 ; a second wall part 3 b that is a plane located on a side opposite to the first wall part 3 a in the tool rotation direction T and facing the tool rotation direction T; and a third wall part 3 c that is a plane located on the same side as the first wall part 3 a in the tool rotation direction T and facing the side opposite to the tool rotation direction T.
  • the second and third wall parts 3 b and 3 c are formed such that a gap therebetween in the circumferential direction becomes greater toward the outer peripheral side, and the second wall part 3 b out of these wall parts extends toward the outer peripheral side so as to tilt to the tool rotation direction T.
  • a fourth wall part 3 d and a fifth wall part 3 e are formed in the shape of a concave cylindrical surface centered on a straight line parallel to the axis O at a boundary part between the first and second wall parts 3 a and 3 b and a boundary part between the first and third wall parts 3 a and 3 c, respectively.
  • the fourth wall part 3 d connects with the first and second wall parts 3 a and 3 b
  • the fifth wall part 3 e connects with the first and third wall parts 3 a and 3 c.
  • the radius of the concave cylindrical surface as the fourth wall part 3 d formed at the boundary part between the first and second wall part 3 a and 3 b is greater than the radius of the concave cylindrical surface as the fifth wall part 3 e formed at the boundary part between the first and third wall parts 3 a and 3 c.
  • a discharge groove 2 C for cuttings is formed which extends toward the posterior end side in parallel with the axis O from the tool rotation direction T side of the bottom surface 3 A of each housing recess 3 and reaches an outer peripheral side of the shank part 2 A beyond the second abutting part 2 B.
  • Each discharge groove 2 C forms a substantially rectangular shape in a cross-section perpendicular to the axis O and is open to an outer peripheral surface of the tip part of the pilot bit 2 .
  • a bottom surface of each discharge groove 2 C which faces the outer peripheral side of the pilot bit 2 forms a recessed curved shape and is slightly swept toward the outer peripheral side in a place where the bottom surface reaches a posterior end of the second abutting part 2 B.
  • a portion where this bottom surface and the bottom surface 3 A of the housing recess 3 intersect each other is chamfered by an inclined surface 2 D that intersects with both the bottom surfaces at an obtuse angle.
  • a fitting hole 3 C that has a centerline C parallel to the axis O and has a circular cross-sectional shape is formed on the side opposite to the bottom surface 3 A of each housing recess 3 in the tool rotation direction T.
  • the centerline C of the fitting hole 3 C coincides with the centerline of the concave cylindrical surface as the fourth wall part 3 d formed at the boundary part between the first and second wall parts 3 a and 3 b, and is eccentric to the outer peripheral side of the axis O.
  • the internal diameter (radius) of the fitting hole 3 C is approximately equal to or slightly smaller than the radius of the concave cylindrical surface as the fourth wall part 3 d.
  • a bit head 4 is attached to each of the housing recesses 3 of the pilot bit 2 .
  • a columnar shaft part 4 A to be inserted and slidably fitted into the fitting hole 3 C and a head main body 4 B provided on the tip side of the shaft part 4 A are integrally formed using metallic materials, such as a steel material.
  • the bit head 4 is attached so as to be rotatable around the centerline C.
  • the bit head 4 is positioned in a state where as shown in FIG. 2 , the head main body 4 B abuts against the first wall part 3 a and is housed within the housing recess 3 and the radius thereof from the axis O is reduced, or is positioned in a state where as shown in FIG. 3 , the head main body 4 B abuts against the second wall part 3 b and the radius thereof from the axis O is enlarged.
  • a posterior end surface of the head main body 4 B is a plane perpendicular to the centerline C.
  • a cutout 4 C is formed at an outer periphery of the shaft part 4 A such that the cutout 4 C forms a semi-oval shape as shown in FIG. 1 in a cross-section along the centerline C and extends to form a substantial L-shape as shown in FIGS. 2 and 3 in a section perpendicular to the centerline C.
  • a pin 5 is driven into the tip part of the pilot bit 2 in a tangential direction of the fitting hole 3 C in the cross-section orthogonal to the axis O, at a position that faces the cutout 4 C in the direction of the axis O in a state where the shaft part 4 A is inserted into the fitting hole 3 C, a posterior end surface of the shaft part 4 A is made to abut against the bottom surface of the fitting hole 3 C, and a posterior end surface of the head main body 4 B is made to abut against the bottom surface 3 A of the housing recessed portion 3 .
  • a peripheral surface of each pin 5 is exposed inside the fitting hole 3 C and is engaged with the cutout 4 C, and thereby the bit head 4 is prevented from coming off to the tip side while being made to be rotatable around the centerline C.
  • a first side surface 4 a which is located on an extension of an outer peripheral surface of the shaft part 4 A among side surfaces of the head main body 4 B, is formed in the shape of a convex cylindrical surface centered on the centerline C which flushes with this outer peripheral surface of the shaft part 4 A or has an external diameter slightly greater than that of the outer peripheral surface of the shaft part 4 A.
  • the first side surface 4 a is made to be slidable on the fourth wall part 3 d of the wall surface 3 B of the housing recess 3 .
  • second and third side surfaces 4 b and 4 c that sandwich the first side surface 4 a therebetween are formed in a planar shape. As shown in FIG.
  • the second side surface 4 b out of these side surfaces is made to abut against the first wall part 3 a of the wall surface 3 B of the housing recess 3 while the third side surface 4 c faces the outer peripheral side of the pilot bit 2 .
  • the third side surface 4 c is made to abut against the second wall part 3 b while the second side surface 4 b is directed to the tool rotation direction T.
  • a fourth side surface 4 d which is located between the second and third side surfaces 4 b and 4 c on a side opposite to the first side surface 4 a, is formed so as to protrude to the outer periphery of the pilot bit 2 and be located on a cylindrical surface centered on the axis O, as shown in FIG. 3 in a state where the bit head 4 is extended.
  • an intersecting ridgeline part between the fourth side surface 4 d and the third side surface 4 c is formed so as to be chamfered by a cylindrical surface that has a diameter slightly smaller than the external diameter of the tip part of the pilot bit 2 and is centered on the axis O in a state where the bit head 4 is retracted as shown in FIG. 2 . Accordingly, the head main body 4 B retracted and housed in the housing recess 3 is located inside a cylindrical surface of the outer peripheral surface of the tip part of the pilot bit 2 .
  • the fourth side surface 4 d is formed in a multi-stage (three-stage in the present embodiment) shape that becomes concave and convex to the inner and outer peripheral sides with respect to the axis O toward the direction of the centerline C as shown in FIG. 1 .
  • a stage at the most posterior end among these stages is made to protrude to the outermost peripheral side from the axis O, and a portion in which the stage at the most posterior end is formed serves as a third abutting part 4 D in the present embodiment.
  • the third abutting part 4 D has a surface thereof facing the tip side which is a flat surface perpendicular to the centerline C, and a greatest radius R of the third abutting part 4 D from the axis O is greater than a radius r of the outer peripheral parts of the tips of the casing pipe 1 and the casing top 1 A from the axis O in a state where the bit head 4 is extended as shown in FIG. 1 .
  • an intersecting ridgeline part between the fourth side surface 4 d and the second side surface 4 b in which the third abutting part 4 D is formed is chamfered in the shape of a convex cylindrical surface with a radius approximately equal to a concave cylindrical surface as the fifth wall part 3 e of the housing recess 3 , and as shown in FIG. 2 , is made to abut against the fifth wall part 3 e in a state where the bit head 4 is retracted.
  • a stage at a foremost end of the fourth side surface 4 d slightly tilts toward the posterior end side so as to become closer to the inner peripheral side in a stage where the bit head 4 is extended.
  • the fourth side surface 4 d is formed so as to extend in parallel with the axis O. Furthermore, an engaging part 4 E is formed at a corner part where that the fourth side surface 4 d the second side surface 4 b intersect with each other in this middle stage, such that the engaging part 4 E cuts out the corner part in a substantial L-shape in a section orthogonal to the centerline C.
  • the engaging part 4 E has a first wall surface 4 e facing the outer peripheral side and a second wall surface 4 f facing the tool rotation direction T, in a state where the bit head 4 is extended, a bottom surface 4 g that is made to be flush with a surface of the third abutting part 4 D which faces the tip side, and a ceiling surface 4 h that faces the bottom surface 4 g in parallel therewith and faces the posterior end side.
  • the first wall surface 4 e is located on a cylindrical surface that has a slightly greater external diameter than the second abutting part 2 B of the pilot bit 2 and is centered on the axis O, and the second wall surface 4 f is formed such that the second wall surface 4 f extends toward the outer peripheral side so as to slightly tilt to the tool rotation direction T.
  • an intersecting ridgeline part between a stage at a foremost end of the fourth side surface 4 d and a tip surface of the head main body 4 B is formed as an inclined surface that extends toward the centerline C so as to become closer the tip side in such a manner the surface forms a truncated conical surface shape centered on the axis O in a state where the bit head 4 is extended.
  • an intersecting ridgeline part between the tip surface and the outer peripheral surface in the pilot bit 2 is also formed as an inclined surface that similarly forms a truncated conical surface shape centered on the axis O and tilts toward the inner peripheral side so as to become closer the tip side, except for the portion cutout by the housing recess 3 .
  • tip surface of the pilot bit 2 and the tip surface of the head main body 4 B of the bit head 4 except the portions made to have these inclined surfaces are respectively flat surfaces perpendicular to the axis O and the centerline C.
  • the length of the head main body 4 B in the direction of the centerline C is equal to the depth from the bottom surface 3 A of the housing recess 3 to the tip surface of the pilot bit 2 . Therefore, the tip surfaces of the pilot bit 2 and the head main body 4 B become flush with each other in a state where the bit head 4 is housed in the housing recess 3 .
  • the tip surfaces and the respective inclined surfaces of the pilot bit 2 and the head main body 4 B of the bit head 4 are provided with a plurality (large number) of drilling tips 6 made of cemented carbide or the like which is harder than a steel material or the like that forms the pilot bit 2 and the bit head 4 .
  • Each of the drilling tips 6 is one in which, for example, hemispherical head part protruding from the tip surfaces and the inclined surfaces and columnar trunk part which are integrally formed, and is fixed by press-fitting, hot-shrink fitting, cold-shrink fitting, or brazing the trunk parts into each of circular holes formed perpendicularly to the tip surfaces and the inclined surfaces.
  • annular ring bit 7 is disposed coaxially with the axis O on the tip side of the casing pipe 1 .
  • the ring bit 7 is also formed in an annular plate shape using metallic materials, such as a steel material, and a tip surface and a posterior end surface thereof that face the direction of the axis O are perpendicular to the axis O.
  • the intersecting ridgeline part between the tip surface and the outer peripheral surface is made to be a truncated cone-shaped inclined surface centered on the axis O.
  • the drilling tips 6 made of hard materials, such as cemented carbide, are also provided on the inclined surface and the outer peripheral part of the tip surface so as to protrude perpendicularly thereto, similar to the pilot bit 2 and the bit head 4 .
  • the external diameter of the ring bit 7 is greater than the external diameter of the casing pipe 1 and the casing top 1 A and greater than the external diameter of the extended bit head 4 .
  • the internal diameter of the ring bit 7 is slightly greater than the external diameter of the second abutting part 2 B of the pilot bit 2 and therefore greater than the internal diameter of the smaller-diameter part 1 B formed within the casing pipe 1 by the casing top 1 A.
  • the internal diameter of the ring bit 7 is smaller than the external diameter of the extended bit head 4 and is of such a size that the first wall surface 4 e of the engaging part 4 E is fittable.
  • the thickness of the ring bit 7 in the direction of the axis O is smaller than the width between the external and internal diameters of the ring bit 7 , and is slightly smaller than a gap between the bottom surface 4 g and the ceiling surface 4 h of the engaging part 4 E.
  • each of the recessed portions serves as a part 7 A to be engaged that is engaged with the engaging part 4 E of each bit head 4 in the tool rotation direction T during drilling.
  • the part 7 A to be engaged includes a first wall surface 7 a that recedes by one step from the inner peripheral part of the ring bit 7 to the outer peripheral side and then faces the inner peripheral side, a second wall surface 7 b facing the side opposite to the tool rotation direction T and a third wall surface 7 c facing the tool rotation direction T which extend from the first wall surface 7 a to the inner peripheral part.
  • the part 7 A to be engaged is formed so as to pass through the ring bit 7 in the direction of the axis O.
  • the first wall surface 7 a among these surfaces is located on the cylindrical surface centered on the axis O.
  • the radius of the first wall surface 7 a from the axis O is slightly greater than the radius of the stage at the foremost end and the middle stage from the axis O in the fourth side surface 4 d of the extended bit head 4 which faces the outer peripheral side and is smaller than the radius R of the third abutting part 4 D.
  • the circumferential length of the first wall surface 7 a is slightly greater than a length except the engaging part 4 E in the circumferential length of the middle stage of the fourth side surface 4 d.
  • Each first blow hole 8 A is open to the tip side of the second abutting part 2 B in the outer peripheral surface of the tip part of the pilot bit 2 .
  • a fourth blow hole 8 D with a much smaller diameter branches from each first blow hole 8 A in parallel with the axis O and is open to the center of the bottom surface of the fitting hole 3 C.
  • each second blow hole 8 B branches from the supply hole 8 at a position closer to the tip side than each first blow hole 8 A, and is open substantially perpendicularly to the inclined surface 2 D between the bottom surface of each discharge groove 2 C for cuttings and the bottom surface 3 A of each housing recess 3 .
  • each third blow hole 8 C has a greater diameter than the first and second blow holes 8 A and 8 B, branches at the tip of the supply hole 8 , and is open to the fifth wall part 3 e side of the first wall part 3 a of the housing recess 3 .
  • the pilot bit 2 is inserted from the posterior end side of the casing pipe 1 in a state where the bit head 4 is retracted and the head main body 4 B is housed in the housing recess 3 , and is positioned in the direction of the axis O in a place where the second abutting part 2 B abuts against the posterior end surface of the casing top 1 A.
  • the head main body 4 B being housed, as shown in FIG.
  • a circumferential position of the part 7 A to be engaged is aligned with the housing recess 3 , and the ring bit 7 is inserted into the tip part of the pilot bit 2 from the tip side and is disposed at the position of the engaging part 4 E of the head main body 4 B in the direction of the axis O.
  • the ring bit 7 When, from this state, the ring bit 7 is relatively rotated to the side opposite to the tool rotation direction T during drilling while the bit head 4 is being extended, as shown in FIG. 3 , the second wall surface 4 f in the engaging part 4 E of the extended bit head 4 comes in close contact with and abuts against the second wall surface 7 b in the part 7 A to engaged of the ring bit 7 and thereby is engaged with the part 7 A to be engaged, and the third side surface 4 c in the head main body 4 B abuts against the second wall part 3 b of the housing recess 3 and is supported by the housing recess 3 . Thereby, the ring bit 7 becomes integrally rotatable with respect to the pilot bit 2 and the bit head 4 in the tool rotation direction T.
  • the portion of the part 7 A to be engaged on the tool rotation direction T side in the tip surface of the ring bit 7 faces the ceiling surface 4 h of the engaging part 4 E with a slight gap therefrom and is abuttable against the ceiling surface 4 h, the ring bit 7 is prevented from coming off to the tip side. That is, in the present embodiment, the portion of the part 7 A to be engaged on the tool rotation direction T side in the tip surface of the ring bit 7 serves as a first abutting part 7 B that is abuttable against the extended bit head 4 , on the tip side in the direction of the axis O.
  • the pilot bit 2 is rotated to the side opposite to the tool rotation direction T during drilling by the drilling device. Then, the head main body 4 B of the bit head 4 is guided by friction with the borehole and by the third wall surface 7 c of the part 7 A to be engaged, and thereby the bit head 4 is retracted as shown in FIG. 2 .
  • the pilot bit 2 and the bit heads 4 can be recovered with the ring bit 7 being left in the borehole by pulling out the pilot bit 2 together with the down-the-hole hammer H as it is from the casing pipe 1 .
  • the pilot bit 2 and the bit head 4 protrude by one step to the tip side of the ring bit 7 as shown in FIG. 1 . Therefore, the drilling tips 6 on the ring bit 7 drill an outer peripheral part of the borehole of which an inner peripheral part is drilled by the drilling tips 6 on the pilot bit 2 and the bit head 4 , and becomes apt to be crushed. For this reason, the load to the ring bit 7 can be reduced, and more efficient drilling can be performed.
  • the tip surfaces of the pilot bit 2 and the bit head 4 may be made to be flush with the tip surface of a ring bit 7 , and the tip surface of the ring bit 7 may protrude from the tip surfaces of the pilot bit 2 and the bit head 4 .
  • the outer peripheral side of the borehole is drilled by the ring bit 7 , in the pilot bit 2 and the bit head 4 , it is not necessary to make the radius of the extended head main body 4 B from the axis O as large as the internal diameter of the borehole. For this reason, a burden to the shaft part 4 A of the bit head 4 or the like can be reduced, and damage can be prevented.
  • the ring bit 7 forms an annular shape, the number and positions of the drilling tips 6 can be relatively freely set, for example, like the drilling tips 6 being disposed in ranges other than a range in the circumferential direction where the extended bit head 4 as shown in FIG. 3 is located. Therefore, degradation of the drilling performance resulting from partial insufficiency of the drilling tips 6 can also be prevented.
  • the inner peripheral part of the borehole is drilled by the drilling tips 6 on the pilot bit 2 and the bit head 4 .
  • a recessed portion that is recessed toward the outer peripheral side is formed in the inner peripheral part of the ring bit 7 , and serves as the part 7 A to be engaged.
  • the load resulting from the rotating force may be concentrated on the protrusion to cause damage, and the volume of the ring bit 7 may also become as great as the protrusion and material cost may increase.
  • it is possible to receive the rotating force with a main body itself of the annular ring bit 7 and the volume and cost of the ring bit 7 can be further reduced.
  • the portion adjacent to the part 7 A to be engaged at the tool rotation direction T side thereof which is formed as the recessed portion recessed from the inner peripheral part toward the outer peripheral side in this way in the tip surface of the ring bit 7 faces the ceiling surface 4 h of the engaging part 4 E, and serves as the first abutting part 7 B abuttable against the ceiling surface 4 h of the engaging part 4 E on the tip side in the direction of the axis O.
  • the bottom surface that faces the tip side may be formed in this recessed portion so as to face the ceiling surface 4 h, and may be used as the first abutting part 7 B.
  • the casing top 1 A is attached to the tip part of the casing pipe 1 to form the smaller-diameter part 1 B, and the second abutting part 2 B of the pilot bit 2 is made to abut against the smaller-diameter part 1 B so as to transmit the striking force and the impelling force.
  • the internal diameter of the ring bit 7 is increased with respect to the internal diameter of this smaller-diameter part 1 B.
  • construction cost can be reliably reduced compared to the drilling tool described in PTL 1 in which the internal diameter of the ring bit has to be made smaller.
  • the internal diameter of the ring bit 7 may be equal to the smaller-diameter part 1 B.
  • the striking force and the impelling force are transmitted by providing the casing pipe 1 with the smaller-diameter part 1 B in this way.
  • the striking force and the impelling force are not directly transmitted from the pilot bit 2 unlike the drilling tool described in PTL 1, but the bit head 4 is provided with the third abutting part 4 D that is abuttable against the posterior end surface of the ring bit 7 in an extended state so as to transmit the striking force and the impelling force from the third abutting part 4 D.
  • the smaller-diameter part 1 B is provided as described above, it is unnecessary to make the internal diameter of the ring bit 7 still smaller, and it is possible to reduce construction cost even more reliably.
  • the striking force and the impelling force can be more reliably transmitted to the ring bit 7 on the outer peripheral side where drilling is performed, and even in a case where a borehole with a greater internal diameter than the external diameter of the casing pipe 1 as in the present embodiment is formed, it is possible to perform drilling much more efficiently.
  • the striking force and impelling force are transmitted from the third abutting part 4 D that is enlarged and has the larger radius R than the radius r of the outer peripheral part of the tip of the casing pipe 1 to the ring bit 7 in this way, it is possible to reliably form a borehole with a large internal diameter without impairing the strength or rigidity of the ring bit 7 even if the thickness of the ring bit 7 in the direction of the axis O is smaller than the width between the external and internal diameters of the ring bit 7 like, for example, the present embodiment. Therefore, according to the present embodiment, the volume of the ring bit 7 can be further reduced, and a much greater reduction of construction cost can be achieved.
  • the drilling tool of the present invention even in a case where a borehole with a greater internal diameter than the external diameter of the casing pipe is formed, it is possible to transmit sufficient rotating force, striking force, and impelling force to the ring bit and to perform efficient drilling, without causing degradation of drilling performance, an increase in construction cost, or damage to the tool. Therefore, the present invention can be industrially applied.

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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)
US15/501,975 2014-08-20 2015-08-11 Drilling tool Abandoned US20170234075A1 (en)

Applications Claiming Priority (3)

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JP2014-167602 2014-08-20
JP2014167602A JP6330573B2 (ja) 2014-08-20 2014-08-20 掘削工具
PCT/JP2015/072799 WO2016027739A1 (ja) 2014-08-20 2015-08-11 掘削工具

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US20170234075A1 true US20170234075A1 (en) 2017-08-17

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US (1) US20170234075A1 (de)
EP (1) EP3184729B1 (de)
JP (1) JP6330573B2 (de)
KR (1) KR20170042568A (de)
CN (1) CN106661924A (de)
AU (1) AU2015304423A1 (de)
CA (1) CA2957394A1 (de)
WO (1) WO2016027739A1 (de)

Cited By (3)

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US9869134B2 (en) * 2013-03-14 2018-01-16 Mitsubishi Materials Corporation Drilling tool
WO2020018780A1 (en) * 2018-07-20 2020-01-23 Baker Hughes a GE Company, LLC Passively adjustable elements for earth-boring tools and related tools and methods
US11280153B2 (en) 2017-08-10 2022-03-22 Kureha Corporation Plug, retaining member, and method for well completion using plug

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EP3517725B1 (de) * 2016-09-23 2021-07-28 Mmc Ryotec Corporation Bohrwerkzeug
CN108868628A (zh) * 2017-07-31 2018-11-23 天信国际集团有限公司 钻孔装置
CN107401375B (zh) * 2017-08-21 2023-04-07 福建亿钻机械有限公司 一种可检测钻杆安装情况的定向钻机及钻洞方法
CN107386972B (zh) * 2017-08-21 2023-04-07 福建亿钻机械有限公司 一种可防触电的水平定向钻机及水平定向钻洞方法
CN107401376B (zh) * 2017-08-21 2023-04-07 福建亿钻机械有限公司 一种可远程监控的水平定向钻机及水平钻洞方法
CN108979655B (zh) * 2018-08-03 2020-10-30 诸暨市惠中智能科技有限公司 一种用于顶管施工的钻孔装置
CN108979656B (zh) * 2018-08-03 2020-07-21 临泉县贝拉蜜家纺有限公司 一种用于顶管施工的刨土机
CN111270985A (zh) * 2018-12-05 2020-06-12 武穴市金锐精密锻造有限公司 一种可变径的潜孔钻头

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JP3750441B2 (ja) * 1999-09-27 2006-03-01 三菱マテリアル株式会社 掘削工具
JP3864645B2 (ja) * 1999-11-22 2007-01-10 三菱マテリアル株式会社 掘削工具
JP3903876B2 (ja) * 2002-08-15 2007-04-11 三菱マテリアル株式会社 掘削工具
JP4844279B2 (ja) * 2006-08-04 2011-12-28 三菱マテリアル株式会社 掘削工具
JP4943824B2 (ja) * 2006-11-17 2012-05-30 ユニタック株式会社 貫通孔の形成方法
CN101571031A (zh) * 2009-06-17 2009-11-04 北京中煤矿山工程有限公司 大直径反井钻井分体式扩孔钻头及其拼装方法
JP5849671B2 (ja) * 2011-12-09 2016-02-03 三菱マテリアル株式会社 掘削工具
CN203257331U (zh) * 2013-04-11 2013-10-30 安徽恒源煤电股份有限公司 一种煤矿钻孔施工钻头
CN203499568U (zh) * 2013-08-28 2014-03-26 中国地质科学院勘探技术研究所 一种分体式pdc导向扩孔钻头

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9869134B2 (en) * 2013-03-14 2018-01-16 Mitsubishi Materials Corporation Drilling tool
US11280153B2 (en) 2017-08-10 2022-03-22 Kureha Corporation Plug, retaining member, and method for well completion using plug
WO2020018780A1 (en) * 2018-07-20 2020-01-23 Baker Hughes a GE Company, LLC Passively adjustable elements for earth-boring tools and related tools and methods

Also Published As

Publication number Publication date
JP6330573B2 (ja) 2018-05-30
EP3184729A1 (de) 2017-06-28
KR20170042568A (ko) 2017-04-19
EP3184729B1 (de) 2019-05-08
EP3184729A4 (de) 2018-04-18
CA2957394A1 (en) 2016-02-25
CN106661924A (zh) 2017-05-10
JP2016044415A (ja) 2016-04-04
AU2015304423A1 (en) 2017-03-02
WO2016027739A1 (ja) 2016-02-25

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