JP7223403B2 - Drilling rig and drilling method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a drilling device having a drilling bit and a drilling method using the same.

Conventionally, as a method of constructing a heat collection tube in the ground, a casing as an outer cylindrical part constituting an excavation jig is rotated to a predetermined depth in the ground with the tip opening closed, and buried in the casing. A method of inserting a heat collection tube and injecting a predetermined amount of aqueous solution is known (see, for example, Patent Document 1).

In the method of Patent Document 1, when pulling out the embedded casing, first, the tip opening of the casing is opened. Then, while rotating the casing, remove the heat collection tube and part of the aqueous solution from the inside of the casing, put the filler into the casing, pull out the casing from the ground, and bury the heat collection tube and the filler in the ground. ing.

In addition, there is known a method of constructing a subterranean heat exchanger that performs heat exchange between the subterranean heat and the heat exchange medium by burying the heat exchange medium in the ground (for example, see Patent Document 2). ).

In the construction method of Patent Document 2, a penetration step of penetrating a cylindrical casing having a cover attached to the tip so as to penetrate to a predetermined depth, and a hollow pipe inside the casing. a casing extracting step of extracting at least the casing main body in a state where the body is arranged;

JP 2013-145072 A JP 2009-228419 A

However, in the conventional construction methods of Patent Documents 1 and 2, the casing is penetrated into the ground by wings or wings provided on the outer circumference of the casing. Therefore, when extracting the casing from the ground, it is necessary to rotate the casing in the opposite direction to when it is penetrated. Therefore, the process of extracting the casing becomes complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an excavating apparatus and an excavating method using the same, in view of the problems of the prior art.

The drilling rig of the present invention is
a drilling bit;
an outer cylindrical portion that transmits the applied pressing force and rotational force in the excavation direction to the excavation bit connected to the front end portion;
a connecting mechanism that connects the outer cylindrical portion and the drilling bit to each other;
The connecting mechanism is
an inner convex portion protruding inward from the front end portion of the outer cylindrical portion;
It is arranged inside the outer cylindrical portion and couples the outer cylindrical portion together with the inner convex portion to the excavating bit so as to be able to release the connection state by sandwiching the inner convex portion and the drilling bit. and a coupling member.

According to the present invention, the drilling bit is opposed to the ground while the outer cylinder and the drilling bit are connected to each other by the connecting mechanism, and the drilling bit is applied with a pressing force and a rotational force to the outer cylinder. Excavation of the ground is performed and the barrel can be advanced into the ground.

When the drilling is completed to the desired position, the coupling member is released from the drilling bit. As a result, the connection between the outer cylindrical portion and the drilling bit is also released.

After this, the connecting member is recovered, leaving the drilling bit in the ground. After that, a heat exchange pipe can be laid by inserting a heat exchange pipe into the outer cylinder and pulling up the outer cylinder while filling the outer cylinder with sand or the like to recover the sand. At this time, since the outer cylinder part is pulled up while the excavation bit remains in the ground, the outer cylinder part can be easily pulled out.

In the present invention, the connecting member and the drilling bit are connected to each other by applying a rotational force in the same direction as the excavating direction to the connecting member, and by applying a rotational force in the opposite direction. Preferably, the coupling is arranged to be released.

According to this, part of the rotational force in the excavation direction transmitted to the excavation bit can be transmitted to the excavation bit via the coupling member.

In the present invention, the drilling bit has a female threaded portion at its rear end portion, the coupling member has a male threaded portion to be screwed with the female threaded portion, and the coupling of the coupling member to the drilling bit comprises the female threaded portion and the threaded portion. It may be performed by screwing with the male screw portion. According to this, the coupling of the coupling member to the drilling bit can be easily released simply by rotating the coupling member.

In the present invention, engaging projections are provided on one or the other of the front end portion of the outer cylindrical portion and the rear end portion of the drilling bit and mesh with each other when the coupling member is coupled to the drilling bit. It is preferred to have a portion and a mating recess. According to this, a large rotational force applied to the outer cylindrical portion can be transmitted to the excavation bit through the engaging projections and the engaging recesses without hindrance, and the excavation bit can perform excavation with a large rotational force.

In the present invention, the inner convex portion of the outer cylindrical portion protrudes inward through a forward-facing front-side step surface and a rear-facing rear-side step surface, and the coupling member and the drilling bit are connected to each other. A rear contact surface facing forward and contacting the rear stepped surface when coupled to the gear and a front contact surface facing rearward and contacting the front stepped surface, wherein the meshing protrusion and the meshing recess are provided. may be provided on one and the other of the front step surface and the front contact surface, respectively.

According to this, the connecting mechanism is configured such that the rear contact surface is brought into contact with the rear step surface, the front contact surface is brought into contact with the front step surface, and the mating protrusion and the mating recess are engaged with each other. By connecting the connecting member to the drilling bit, the outer cylindrical portion can be reliably connected to the drilling bit.

A drilling rig according to another aspect of the present invention comprises:
a drilling bit;
an outer cylindrical portion that transmits the applied pressing force and rotational force in the excavation direction to the excavation bit connected to the front end portion;
a connecting mechanism that connects the outer cylindrical portion and the drilling bit to each other;
The connecting mechanism is
a first inner convex portion protruding inward from the front end portion of the outer cylindrical portion;
a second inner protrusion protruding inward from the rear end of the drilling bit;
The outer cylinder is arranged inside the outer cylinder, and is fixed by sandwiching the first inner convex part and the second inner convex part from the front and rear to couple the outer cylinder part to the drilling bit and release the fixation. and coupling means for releasing the coupling.

According to this method, the connecting means is recovered while the drilling bit remains in the ground, and then a pipe for heat exchange is inserted into the outer cylinder. By pulling up and recovering the heat, pipes for heat exchange can be laid. At this time, since the outer cylinder part is pulled up while the excavation bit remains in the ground, the outer cylinder part can be easily pulled out.

In this case, in a preferred embodiment,
The coupling means are
a plurality of clamping members annularly arranged on the inner side from the front end of the outer cylindrical portion to the rear end of the drilling bit and having a partially conical inner surface and an outer surface whose diameter decreases toward the front;
a support member disposed inside the front end portion of the outer cylindrical portion and the rear end portion of the drilling bit and supporting the plurality of holding members so as to be movable between a first position and a second position;
a locking member that moves the holding members to the first position when inserted inside the plurality of holding members from above, and moves the holding members to the second position when pulled upward thereafter; with
Each holding member abuts against the rear side of the first inner protrusion and the front side of the second inner protrusion when positioned at the first position, and corresponds when positioned at the second position. Having a first outer protrusion and a second outer protrusion that are released from contact,
The locking member has a first sliding surface that slides on the inner surface of the partial conical shape to move the support member to the first position, and an outer surface of the partial conical shape that slides on the supporting member. A second sliding surface is provided for moving the member to the second position.

The drilling method of the present invention is
An excavation step of excavating the ground using the above excavation equipment;
a coupling release step of releasing coupling between the drilling bit of the drilling rig and the outer cylindrical portion by the coupling means of the drilling rig after the completion of the drilling step;
a recovery step of recovering the coupling means after completion of the coupling release step;
and an outer cylinder extracting step of extracting the outer cylinder part with the excavation bit retained after the completion of the recovering step.

According to this, since the ground is excavated using the excavating device, the outer cylindrical portion can be easily extracted with the excavating bit left in place after the excavation is completed.

FIG. 1A is a perspective view showing an excavating apparatus according to a first embodiment of the present invention, and FIG. 1B is an exploded perspective view showing the excavating apparatus. 1B is a cross-sectional view of a coupling mechanism portion of the excavating rig of FIG. 1A; FIG. 3A is a cross-sectional view of a bit connecting portion of a drilling bit in the drilling rig of FIG. 1, and FIG. 3B is a plan view thereof. 4A is a bottom view of the distal end portion of the outer cylinder in the drilling rig of FIG. 1, and FIG. 4B is a cross-sectional view thereof. FIG. 5 is a cross-sectional view of a tip portion of a drilling rig according to a second embodiment of the present invention; Figure 6 is a cross-sectional view of the coupling means of the drilling rig of Figure 5; 7A is a plan view of the coupling means of FIG. 6, and FIG. 7B is a cross-sectional view of the support member in FIG. 7A taken along line BB. 8A-8D are diagrams showing the procedure for installing a heat exchanger using the drilling rig of FIG. 9A-9D are diagrams showing the procedure for installing a heat exchanger using the drilling rig of FIG.

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B show a drilling rig according to one embodiment of the invention. As shown in FIG. 1, the excavator 1 includes an excavation bit 2, an outer cylinder portion 3 that transmits applied pressing force and rotational force in the excavation direction to the excavation bit 2 connected to the front end, and an outer cylinder. A connecting mechanism 4 (see FIG. 2) for connecting the portion 3 and the drilling bit 2 to each other.

The excavation bit 2 includes a bit distal end portion 5 having an auger screw and an auger head, and a bit connecting portion 6 fixed to the rear side of the bit distal end portion 5 and used for connection with the outer cylinder portion 3 .

FIG. 2 shows a cross-section of the connecting mechanism 4 portion of the drilling rig 1 . The connecting mechanism 4 includes an annular inner convex portion 7 projecting inward from the front end portion of the outer cylindrical portion 3, and an inner convex portion 7 disposed inside the outer cylindrical portion 3. A coupling member 8 is provided for coupling the outer cylindrical portion 3 to the excavation bit 2 so as to release the coupling state together with the convex portion 7 .

The connecting member 8 and the excavating bit 2 are connected to each other by applying a rotational force in the same direction as the excavating direction to the connecting member 8, and are released by applying a rotational force in the opposite direction. configured as

Specifically, the bit connecting portion 6 of the excavation bit 2 is provided with a female threaded portion 9 , and the coupling member 8 has a male threaded portion 10 that screws together with the female threaded portion 9 . The connecting member 8 is connected to the drilling bit 2 by screwing the female threaded portion 9 and the male threaded portion 10 together.

The outer cylinder portion 3 includes a cylindrical portion 11 to which the above-described pressing force and rotational force are applied to the rear end portion, and a hollow cylindrical outer cylinder front end portion 12 welded to the outside of the front end portion of the cylindrical portion 11. . The above-mentioned inner convex portion 7 is formed of a cylindrical member provided from the inside of the tip portion of the cylindrical portion 11 to the inside of the intermediate portion of the tip portion 12 of the outer cylinder, and is fixed to the cylindrical portion 11 and the tip portion 12 of the outer cylinder by welding. be done.

The coupling member 8 includes a substantially cylindrical front coupling portion 13 on the front end side, a rear coupling portion 14 on the rear end side, and an annular connecting portion 15 that connects the front coupling portion 13 and the rear coupling portion 14 . and are welded together.

A rotational force for screwing and disengaging the male threaded portion 10 of the coupling member 8 and the female threaded portion 9 of the drilling bit 2 is transmitted to the coupling member 8 by a member inserted into the cylindrical portion 11 of the outer cylinder portion 3 . A connecting portion 14a for connecting this member is provided at the rear end portion of the rear end side connecting portion 14 of the connecting member 8. As shown in FIG.

3A shows a cross section of the bit connecting portion 6 of the drilling bit 2, and FIG. 3B shows the bit connecting portion 6 as seen from the rear end side. As shown in FIGS. 3A and 3B, the bit connecting portion 6 has a substantially cylindrical shape and is provided with a mating recess 16 at its rear end.

On the outer periphery of the rear end side of the bit connecting portion 6, an O-ring is provided on the inner side of the front end side of the inner convex portion 7 of the outer cylinder tip portion 12 when connecting the outer cylinder portion 3 and the drilling bit 2. A mating surface 18 is provided which is sealingly mated by 17 .

4A shows the front end of the outer cylinder 3 as viewed from the front end side, and FIG. 4B shows a cross section of the front end. As shown in FIGS. 4A and 4B , the tip of the inner projection 7 of the outer cylinder 3 is fitted with the engagement recess 16 of the bit connecting part 6 when connecting the outer cylinder 3 and the drilling bit 2 . A mating engagement projection 19 is provided. The inner protrusion 7 protrudes inward through a front stepped surface 20 facing forward and a rear stepped surface 21 facing rearward.

As shown in FIG. 2 , the front end coupling portion 13 of the coupling member 8 includes a rear contact surface 22 that is provided rearward of the male threaded portion 10 and contacts the rear stepped surface 21 while facing forward. Further, as shown in FIGS. 3A and 3B, the bit connecting portion 6 of the excavation bit 2 has a front contact surface 23 which is provided at the rear end thereof and contacts the front step surface 20 while facing rearward. That is, the engaging projection 19 is provided on the front step surface 20 and the engaging recess 16 is provided on the front contact surface 23 .

When connecting the front end coupling portion 13 of the coupling member 8 to the bit coupling portion 6, it is necessary to An O-ring 24 ensures a tight seal with the inner surface of the .

In this configuration, when excavating the ground and constructing the heat exchange pipe, first, the rear end of the excavating bit 2 is moved so that the engaging convex portion 19 of the outer cylindrical portion 3 is engaged with the engaging concave portion 16 of the bit connecting portion 6 . The outer cylinder part 3 is arranged on the side.

The coupling member 8 is coupled to the excavation bit 2 by screwing the male threaded portion 10 of the coupling member 8 disposed within the outer cylindrical portion 3 into the female threaded portion 9 of the excavation bit 2 . As a result, the inner convex portion 7 of the outer cylindrical portion 3 is sandwiched and fixed between the drilling bit 2 and the connecting member 8, and the drilling bit 2 is connected to the outer cylindrical portion 3 as shown in FIG. 1A. .

Next, the excavation bit 2 side of the excavator 1 is made to face the ground, and a pressing force and a rotational force in the excavation direction are applied to the outer cylindrical portion 3 . As a result, the excavating bit 2 rotates to excavate the ground, and the outer cylindrical portion 3 advances into the ground. At this time, the rotation of the outer cylindrical portion 3 and the drilling bit 2 also rotates the connecting member 8 that connects them.

In this excavation process, by applying a rotational force in the same direction as the rotation of the excavation bit 2 to the coupling member 8, part of the rotational force in the excavation direction transmitted to the excavation bit 2 is transferred to the coupling member 8. It may be transmitted to the drilling bit 2 via.

When the excavation is completed to the desired depth of the ground, the connecting member 8 is rotated in a direction opposite to the rotation (rotation in the excavation direction) when the outer cylindrical portion 3 is connected to the excavation bit 2 , thereby removing the excavation bit 2 . The male threaded portion 10 of the coupling member 8 is unscrewed from the female threaded portion 9 . As a result, the coupling between the outer cylindrical portion 3 and the excavation bit 2 is released (uncoupling step).

After that, the connecting member 8 is pulled up and recovered. After that, a heat exchange pipe is arranged inside the outer cylindrical portion 3 . Furthermore, the outer cylinder part 3 is pulled up and collected while filling the outer cylinder part 3 with a predetermined filling material (recovery step). Thereby, the pipe for heat exchange can be laid in the ground. Sand or water, for example, corresponds to the predetermined filling.

According to this embodiment, after excavation is completed to a desired position, the connection between the outer cylindrical portion 3 and the excavation bit 2 can be released simply by rotating the connecting member 8 . Therefore, after this, while the excavation bit 2 is left in the ground, the outer cylinder part 3 can be easily extracted from the ground without the need to rotate it (outer cylinder extracting step).

Further, during excavation, the engagement projection 19 of the outer cylinder 3 and the engagement recess 16 of the drilling bit 2 mesh with each other, so that a large rotational force applied to the outer cylinder 3 can be transmitted to the drilling bit 2 without any trouble. can.

Further, since the connecting member 8 and the drilling bit 2 are connected by applying a rotating force in the same direction as the rotating force in the excavating direction to the connecting member 8, the rotating force in the excavating direction is transmitted to the drilling bit 2. can be transmitted to the drilling bit 2 via the coupling member 8 .

Further, by screwing the male threaded portion 10 of the coupling member 8 to the female threaded portion 9 of the excavation bit 2 so that the meshing convex portion 19 of the outer cylinder portion 3 meshes with the meshing recessed portion 16 of the bit connecting portion 6, the outer cylinder portion 3 can be securely connected to the drilling bit 2 . In addition, as a result, a large rotational force applied to the outer cylindrical portion can be transmitted to the drilling bit without any trouble.

FIG. 5 shows a cross-section of the tip of a drilling rig according to a second embodiment of the invention. As shown in FIG. 5, the excavator 1b includes an excavation bit 2b, an outer cylindrical portion 3b for transmitting the applied pressing force and rotational force in the excavation direction to the excavation bit 2b connected to the front end portion, and an outer cylinder portion 3b. A connecting mechanism 4b for connecting the cylindrical portion 3b and the excavation bit 2b to each other is provided.

The drilling bit 2b and the outer cylindrical portion 3b are provided with an engaging concave portion 25 and an engaging convex portion 26 similar to the engaging concave portion 16 in FIG. 3B and the engaging convex portion 19 in FIG. 4B. The engaging concave portion 25 and the engaging convex portion 26 engage with each other when the drilling bit 2b and the outer cylinder portion 3b are coupled to constrain the drilling bit 2b and the outer cylinder portion 3b to each other in the circumferential direction.

The connecting mechanism 4b includes a first inner convex portion 27 protruding inward from the front end portion of the outer cylinder portion 3b, a second inner convex portion 28 protruding inward from the rear end portion of the excavation bit 2b, and the outer cylindrical portion 3b. The outer cylindrical portion 3b is connected to the excavation bit 2b by fixing the first inner convex portion 27 and the second inner convex portion 28 from the front and rear, and the connection is released by releasing the fixing. and coupling means 29 for releasing.

FIG. 6 shows a cross section of the coupling means 29 . As shown in FIG. 6, the coupling means 29 comprises a plurality of clamping members 30 annularly arranged inside from the front end of the outer cylindrical portion 3b to the rear end of the drilling bit 2b. These holding members 30 form an inner side surface 31 and an outer side surface 32 having a partially conical shape, the diameter of which decreases toward the front. In this embodiment, three holding members 30 are used.

The coupling means 29 also includes a support member 35 that supports the three holding members 30 so as to be radially movable between a first position P1 and a second position P2 with their central axes as reference positions. The support member 35 is arranged inside the front end portion of the outer cylinder portion 3b and the rear end portion of the drilling bit 2b.

Movement of the clamping member 30 along the radial direction is guided by causing the ends of the spring pins 36 inserted vertically into the support member 35 to face the radially elongated grooves 37 provided in the clamping member 30 . be done.

7A shows a view of the coupling means 29 from above, and FIG. 7B shows a BB line cross section of the support member 35 in FIG. 7A. As shown in these figures, the support member 35 has three windows 38 that support the three holding members 30 so as to be movable in the radial direction.

As shown in FIG. 6, each holding member 30 contacts the rear side of the first inner protrusion 27 (see FIG. 5) and the front side of the second inner protrusion 28 when positioned at the first position P1. It has a first outer convex portion 39 and a second outer convex portion 40 that are in contact with each other and are released from the contact when positioned at the second position P2.

The connecting mechanism 4b also includes a lock member 41 for moving the clamping member 30 between the first position P1 and the second position P2. When the locking member 41 is inserted inside the plurality of holding members 30 from above, the locking member 41 moves each holding member 30 to the first position P1, and when pulled upward, moves the holding member 30 to the second position P2. move to

To achieve this function, the locking member 41 has a first sliding surface 42 which, when inserted from above, slides against the part-conical inner surface 31 to move each coupling means 29 to the first position P1, and It has a second sliding surface 43 which slides against the part-conical outer surface 32 to move each coupling means 29 to the second position P2 when pulled upwards.

As shown in FIG. 5, the drilling rig 1b comprises a recovery device 44 for recovering the connecting means 29 connecting the outer tube 3b and the drilling bit 2b. The recovery device 44 is provided rotatably about the upper end of the tubular portion 45 having an outer diameter that matches the inner diameter of the outer tubular portion 3 b and the tubular portion 45 . A plurality of hook members 46 having hooks.

Each hook member 46 is urged by a coil spring 47 so that the lower end of each hook member 46 faces toward the central axis of the cylindrical portion 45 . A fixing portion 49 to which the lower end of a chain or wire 48 for pulling up the tubular portion 45 is fixed is provided on the upper surface of the tubular portion 45 . The upper end of the lock member 41 is provided with an engaging portion 50 having a shape in which each hook member 46 opens outward and the hook portion of each hook member 46 engages when the recovery device 44 is lowered from above.

FIGS. 8A to 8D and 9A to 9D show procedures for excavating and installing a heat exchanger by an excavating method using the excavating device 1b. When installing the heat exchanger, first, as shown in FIGS. 8A and 8B, the outer cylindrical portion 3b is connected to the drilling bit 2b by the connecting means 29. As shown in FIGS. Next, as shown in FIG. 8C, the excavation bit 2b is rotated through the outer cylinder portion 3b while adding the outer cylinder portion extension pipe 51 by the working machine, and is inserted into the ground (excavation step).

After this excavation process is completed, the recovery device 44 is suspended by a chain or wire 48 and placed on the engaging portion 50 of the locking member 41, and the hook member 46 of the recovery device 44 is engaged with the engaging portion 50 as shown in FIG. 8D. Then, as shown in FIG. 9A, the chain or wire 48 is pulled up to release the coupling between the excavating bit 2b and the outer cylindrical portion 3b (uncoupling step), and the coupling means 29 is recovered (recovering step).

Next, as shown in FIG. 9B, the heat exchanger 52 is inserted into the outer cylinder part extension pipe 51 and the outer cylinder part 3b to the rear end of the excavation bit 2b, and the gravel 53 with a diameter of 2 to 4 mm is heat-exchanged. It is filled between the container 52 and the outer cylinder part extension tube 51 and the outer cylinder part 3b.

Next, as shown in FIG. 9C, the outer cylinder portion extension tube 51 and the outer cylinder portion 3b are pulled out while being rotated about the central axis (outer cylinder extraction step). This completes the embedding of the heat exchanger 52 as shown in FIG. 9D. The drilling bit 2b is left in the ground.

As described above, according to the present embodiment, the coupling means 29 is recovered by the recovering device 44 to separate the outer cylinder portion 3b from the excavation bit 2b, and the excavation bit 2b is retained in the ground so that the outer cylinder portion extension pipe can be removed. Since 51 and the outer cylindrical portion 3b are removed, this removal can be easily performed.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto. For example, in the first embodiment, the coupling member 8 and the drilling bit 2 are coupled and released by rotating and reversely rotating the coupling member 8 without screwing the male threaded portion 10 and the female threaded portion 9 together. It may also be done by other easily achievable connecting members.

Further, the connection between the connecting member 8 and the excavating bit 2 may be performed by applying a turning force in the direction opposite to the turning force in the excavating direction to the connecting member 8 .

Alternatively, the engagement recess 16 may be provided at the end of the outer cylinder 3, and the engagement protrusion 19 may be provided at the rear end of the drilling bit.

Further, the drilling rigs 1 and 1b are not limited to laying pipes for heat exchange, and may be used for other purposes such as setting wells and boring for monitoring.

DESCRIPTION OF SYMBOLS 1... Drilling apparatus 2, 2b... Drill bit 3, 3b... Outer cylinder part 4... Connection mechanism 5... Bit tip part 6... Bit connection part 7... Inner convex part 8... Coupling member 9... Female threaded portion 10 Male threaded portion 11 Cylindrical portion 12 Outer cylinder tip portion 13 Front end side coupling portion 14 Rear end side coupling portion 14a Connection portion 15 Annular connection portion 16 Engagement recess , 17... O-ring, 18... Fitting surface, 19... Engagement convex part, 20... Front stepped surface, 21... Rear stepped surface, 22... Rear contact surface, 23... Front contact surface, 24... O-ring , 25... engaging concave portion, 26... engaging convex portion, 27... first inner convex portion, 28... second inner convex portion, 29... coupling means, 30... coupling member, 31... inner surface, 32... outer surface, 35... Support member 36 Spring pin 37 Groove 38 Window 39 First outer protrusion 40 Second outer protrusion 41 Lock member 42 First sliding surface 43 Second Sliding surface 44 Recovery device 45 Cylindrical part 46 Hook member 47 Coil spring 48 Chain or wire 49 Fixed part 50 Engagement part 51 Outer tube extension tube 52... Heat exchanger, 53... Gravel.

Claims (8)

a drilling bit;
an outer cylindrical portion that transmits the applied pressing force and rotational force in the excavation direction to the excavation bit connected to the front end portion;
a connecting mechanism that connects the outer cylindrical portion and the drilling bit to each other;
The connecting mechanism is
an inner convex portion protruding inward from the front end portion of the outer cylindrical portion;
It is arranged inside the outer cylindrical portion and couples the outer cylindrical portion together with the inner convex portion to the excavating bit so as to be able to release the connection state by sandwiching the inner convex portion and the drilling bit. A drilling rig, comprising: a coupling member. The connecting member and the excavating bit are connected to each other by applying a rotational force in the same direction as the excavating direction to the connecting member, and are released by applying a rotational force in the opposite direction. 2. The drilling rig of claim 1, wherein the drilling rig is configured to: The drilling bit has a female threaded portion at its rear end, and the coupling member has a male threaded portion that screws together with the female threaded portion. 3. The excavating apparatus according to claim 1, wherein the screwing is performed. an engaging projection and an engaging recess provided at one and the other of the front end portion of the outer cylindrical portion and the rear end portion of the drilling bit and meshing with each other when the coupling member is coupled to the drilling bit; The excavator according to any one of claims 1 to 3, characterized in that it comprises a The inner convex portion of the outer cylindrical portion protrudes inward through a forward-facing front stepped surface and a rearward-facing rear stepped surface, and the coupling member and the drilling bit are coupled to each other. a rear contact surface facing forward and contacting the rear step surface and a front contact surface facing rearward and contacting the front step surface; 5. The excavator according to claim 4, wherein the step surface and the front contact surface are provided on one side and the other side, respectively. a drilling bit;
an outer cylindrical portion that transmits the applied pressing force and rotational force in the excavation direction to the excavation bit connected to the front end portion;
a connecting mechanism that connects the outer cylindrical portion and the drilling bit to each other;
The connecting mechanism is
a first inner convex portion protruding inward from the front end portion of the outer cylindrical portion;
a second inner protrusion protruding inward from the rear end of the drilling bit;
The outer cylinder is arranged inside the outer cylinder, and is fixed by sandwiching the first inner convex part and the second inner convex part from the front and rear to couple the outer cylinder part to the drilling bit and release the fixation. and coupling means for releasing said coupling by means of an excavator. The coupling means are
a plurality of clamping members annularly arranged on the inner side from the front end of the outer cylindrical portion to the rear end of the drilling bit and having a partially conical inner surface and an outer surface whose diameter decreases toward the front;
a support member disposed inside the front end portion of the outer cylindrical portion and the rear end portion of the drilling bit and supporting the plurality of holding members so as to be movable between a first position and a second position;
a locking member that moves the holding members to the first position when inserted inside the plurality of holding members from above, and moves the holding members to the second position when pulled upward thereafter; with
Each holding member abuts against the rear side of the first inner protrusion and the front side of the second inner protrusion when positioned at the first position, and corresponds when positioned at the second position. Having a first outer protrusion and a second outer protrusion that are released from contact,
The locking member has a first sliding surface that slides on the inner surface of the partial conical shape to move the support member to the first position, and an outer surface of the partial conical shape that slides on the supporting member. 7. Drilling rig according to claim 6, comprising a second sliding surface for movement of the member to the second position. an excavating step of excavating the ground using the excavating apparatus according to any one of claims 1 to 7;
a coupling release step of releasing coupling between the drilling bit of the drilling rig and the outer cylindrical portion by the coupling means of the drilling rig after the completion of the drilling step;
a recovery step of recovering the coupling means after completion of the coupling release step;
An excavation method, further comprising: an outer cylinder extracting step of extracting the outer cylinder portion with the excavation bit retained after the completion of the recovering step.

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