JP2016061107A - Hole drilling device for double pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hole drilling device for a double pipe that eliminates a complicated process for connecting an inner rod and prevents transmission of striking force of a down-the-hole hammer to a casing shoe at a tip of an outer casing.SOLUTION: A hole drilling device for a double pipe includes: an inner rod (13) and an outer casing (11) connected to ground-side equipment (20); a pilot bit (15) connected to a tip of the inner rod (13), with a striking force generator (14) in between; and a ring bit (16) disposed on outer side of the pilot bit (15) in a radial direction. The pilot bit (15) has a polygonal cross-section (hexagonal, for example), and a cross-section of an inner wall surface (IS) of the ring bit (16) is of a complimentary form with the cross-section of the pilot bit (15) (polygonal: hexagonal, for example).SELECTED DRAWING: Figure 2

Description

The present invention relates to a double-pipe drilling device for excavating and drilling ground, and relates to a technique using a down-the-hole hammer.

A conventional double pipe drilling device using a down-the-hole hammer will be described with reference to FIG.
In FIG. 17, an inner rod 13 (not shown) extends inside a casing 11 (outer casing), and a down-the-hole hammer 14 is connected to a ground-side tip of the inner rod 13 (not shown). The underground tip of the down-the-hole hammer 14 (lower left side in FIG. 17) is connected to the pilot bit 15. An annular ring bit 16 is provided outside the pilot bit 15 in the radial direction.
The pilot bit 15 has a substantially L-shaped engagement piece 15 </ b> A on the side surface, and the engagement piece 15 </ b> A is engaged with an engagement groove 16 </ b> A formed in the ring bit 16. That is, the pilot bit 15 and the ring bit 16 are connected by engaging the engagement piece 15A of the pilot bit 15 with the engagement groove 16A of the ring bit 16.

A casing shoe 12 is provided at the underground end (lower left end in FIG. 17) of the outer casing 11, and a radial direction is provided at the tip of the casing shoe 12 (underground end: lower left end in FIG. 17). An engaging convex portion 12A protruding inward is formed. Then, the engaging protrusion 12A at the tip of the casing shoe 12 is engaged with the annular groove 16B of the ring bit 16, so that the casing shoe 12 and the ring bit 16 are connected.
In the ring bit 16 of FIG. 17, the annular groove 16B is formed on the ground side (lower left side in FIG. 17) from the engagement groove 16A.

Rotation and thrust from the ground-side boring machine (not shown in FIG. 17) to the inner rod 13 through the swivel joint (not shown in FIG. 17) (movement to feed the inner rod to the underground side in the longitudinal direction) Is supplied. The rotation transmitted to the inner rod 13 is transmitted to the pilot bit 15, and further transmitted to the ring bit 16 by engagement between the engagement piece 15 </ b> A of the pilot bit 15 and the engagement groove 16 </ b> A of the ring bit 16.
Then, the thrust transmitted to the inner rod 13 is transmitted to the pilot bit 15 via the down-the-hole hammer 14, and further, the ring 15 is engaged with the engagement piece 15A of the pilot bit 15 and the engagement groove 16A of the ring bit 16. Bit 16 is transmitted.
Here, since the annular groove 16B of the ring bit 16 and the engaging projection 12A of the casing shoe 12 are engaged, the thrust transmitted to the ring bit 16 is also transmitted to the casing shoe 12 and the outer casing 11, and the outer The casing 11 is entrained by the ring bit 16 and pushed into the underground side (lower left side in FIG. 17).

The striking force generated by the down-the-hole hammer 14 is transmitted to the pilot bit 15 and also transmitted to the ring bit 16 via a striking transmission portion (not shown in FIG. 17).
Then, due to the rotational force, striking force, and thrust transmitted to the pilot bit 15 and the ring bit 16, the tip portion shown in FIG. 17 advances by excavating the ground.

However, in the conventional double pipe drilling apparatus described with reference to FIG. 17, for example, after excavation of the ground, only the outer casing 11 remains to insert the anchor body, and the inner rod 13 is moved to the ground side. In the case of extraction (extubation), as described in FIG. 17, the substantially L-shaped engagement piece 15A of the pilot bit 15 is engaged with the engagement groove 16A of the ring bit 16, so that the pilot bit 15 Since the ring bit 16 is connected, the engagement state between the engagement piece 15A of the pilot bit 15 and the engagement groove 16A of the ring bit 16 is not released only by pulling up the inner rod 13 to the ground side. Even if it is pulled up to the ground side, the end on the ground side of the inner rod 13 cannot be surrounded by the outer casing 11. There.
In the conventional double pipe drilling device described with reference to FIG. 17, in order to extract only the inner rod 13 to the ground side, the inner rod 13 is moved to the ground side before the inner rod 13 is pulled to the ground side. And the engagement groove 16A of the ring bit 16 rotates in a direction opposite to the direction extending in the circumferential direction, so that the engagement piece 15A of the pilot bit 15 and the engagement groove 16A of the ring bit 16 The engaged state had to be released.

Connection of the outer casing 11 and the inner rod 13 in the conventional double pipe drilling device described above will be described with reference to FIGS. 18 and 19.
In the conventional double-pipe drilling device described with reference to FIG. 17, the screwing / unscrewing direction of the threaded portion at the connection location of the outer casing 11 is the screwing of the threaded portion at the connection location of the inner rod 13. It is necessary to make the direction opposite to the mating / unscrewing direction. For example, if the screw portion at the connection location of the inner rod 13 is a right-hand thread, the screw portion at the connection location of the outer casing 11 must be a left-hand screw.

In FIG. 18, the boring machine 20 can engage with the right-handed inner rod 13 and rotate the inner rod 13 in the direction in which the right-hand screw is tightened. However, the boring machine 20 cannot be engaged with the left-handed outer casing 11 to rotate the boring machine 20 in the direction in which the left-handed screw is tightened. Therefore, as shown in FIG. 18, the outer casing 11 is not connected to the boring machine 20, and the gap (annular space) between the outer casing 11 and the inner rod 13 is opened at the upper end portion of the outer casing 11.
In FIG. 18, symbol SL indicates slime that leaks from the open end of the annular space between the outer casing 11 and the inner rod 13. Further, reference numeral α1 is a clamp for fixing the outer casing 11, reference numeral α2 is a clamp for fixing the inner rod, and reference numeral α3 is a final tightening or disconnection when the outer casing 11 and the inner rod 13 are connected / disconnected. A clamp (so-called “breaker”).

When the excavation progresses and the outer casing 11 and the inner rod 13 are to be connected, in the state of FIG. 18, the worker M (see FIG. 19: not shown in FIG. 18) has a double pipe (the outer casing 11 and the inner rod 13). The rod 13) is placed on the already connected double tube. Then, the outer casing 11 is lifted, the inner rod 13 is held by the clamp α2, and the box 21 of the boring machine 20 is screwed into the ground side end of the new inner rod 13 to be connected. Is rotated clockwise (the direction in which the right screw is tightened) to connect the inner rod 13.
When the connection of the inner rod 13 is completed, the holding of the inner rod 13 by the clamp α2 is released, and the outer casing 11 is held by the clamp α1.

Here, as described above, in the boring machine 20 that can connect the inner rod 13 (clockwise, rotate in the direction in which the right screw is tightened), the direction in which the outer casing 11 is connected (counterclockwise: the left screw is tightened). Direction). Therefore, as shown in FIG. 19, the worker M rotates the outer casing 11 (the upper casing in FIG. 19) to be connected counterclockwise (the direction in which the left screw is tightened) and is held by the clamp α1. Connect to the outer casing 1. Finally, the outer casing 11 rotated and connected by the worker M is tightened by the clamp α3 (breaker).
As described above, in the conventional conventional double pipe drilling device, when excavation progresses and the double pipe is connected, the outer casing 11 to be connected by the worker M is counterclockwise (the direction in which the left screw is tightened). To the outer casing 1 held by the clamp α1. And the connection work of the outer casing 11 by the worker M and the breaker α3 increases the labor and cost of the excavation work by the double pipe drilling holes.

Furthermore, in the boring machine 20 that can connect the inner rod 13 (clockwise, rotate in the direction in which the right screw is tightened), it rotates in the direction in which the outer casing 11 is connected (counterclockwise: the direction in which the left screw is tightened). Therefore, in order to extubate the underground outer casing 11 after excavation, it is necessary to prepare a boring machine that rotates in the direction opposite to the boring machine 20 for excavation. Then, preparing two types of boring machines and replacing the boring machine for each type of work increases the labor and cost of work by the double pipe drilling device.
In addition, since the outer casing 11 is not connected to the boring machine 20 as described in FIGS. 18 and 19, the slime SL generated during excavation is separated from the outer casing 11 and the inner casing as shown in FIG. It leaks from the open end of the annular space between the rods 13 and deteriorates the environment of the work site.

Further, in the conventional double pipe drilling device, as shown in FIG. 17, the annular groove 16 </ b> B of the ring bit 16 and the engaging projection 12 </ b> A of the casing shoe 12 are engaged with each other. The striking force is transmitted to the outer casing 11 (or the casing shoe 12 at the tip of the outer casing 11) via the pyrod bit 15 and the ring bit 16.
When the rotational force and thrust are transmitted from the boring machine 20 to the outer casing 11, if the striking force from the down-the-hole hammer 14 is transmitted to the casing shoe 12 at the tip of the outer casing 11, the casing shoe 12 is damaged. There was a fear.
For this reason, it has been conventionally required to prevent the striking force from the down-the-hole hammer 14 from being transmitted to the casing shoe 12 at the tip of the outer casing 11. However, in the related art shown in FIGS. It was not possible to meet.

As another prior art, a double-pipe drilling device has been proposed that does not require the use of a boring machine (boring machine for retreating the outer pipe) other than the drilling boring machine without leaving the outer pipe underground. (See Patent Document 1).
Although such a double pipe drilling device (Patent Document 1) is useful, the problem as described above, that is, the inner rod is pushed into the ground every time the inner rod is connected, and the engagement groove of the ring bit is circular. Rotating in a direction opposite to the direction extending in the circumferential direction, an operation for releasing the engagement state between the engagement piece of the pilot bit and the engagement groove of the ring bit must be performed, from the down-the-hole hammer It is not intended to solve that the impact force is transmitted to the casing shoe at the tip of the outer casing.

JP 2012-140821 A

The present invention has been proposed in view of the above-described problems of the prior art, eliminates the complexity of connecting the inner rod, and the striking force from the down-the-hole hammer is transmitted to the casing shoe at the tip of the outer casing. An object of the present invention is to provide a double-pipe drilling device that can prevent the occurrence of erosion.

The double pipe drilling device (100) of the present invention has an inner rod (13) and an outer casing (11: casing) connected to a ground side machine (20: boring machine),
A pilot bit (15) is connected to the underground side of the inner rod (13), and a ring bit (16) is disposed radially outward of the pilot bit (15),
A casing shoe (12) is connected to the tip of the outer casing (11),
The cross-sectional shape of the pilot bit (15) is formed in a polygonal shape (for example, hexagonal shape), and the cross-sectional shape of the inner wall surface (IS) of the ring bit (16) is complementary to the cross-sectional shape of the pilot bit (15) (hexagonal). Shape).
Here, the term “polygonal shape” is a wording that encompasses all polygonal shapes that are equal to or greater than a triangle.

In carrying out the present invention, the pilot bit (15) is formed with regions (β1, β2, γ1) for transmitting the striking force from the striking force generator (14: down-the-hole hammer, etc.) to the ring bit (16). ,
A concave portion (16C) is formed on the side surface of the ring bit (16), and an engaging portion (12B) protruding radially inward is formed at the ground-side tip of the canning shoe (12). The engaging portion (12B) at the tip of the casing shoe (12) is engaged with the concave portion (16C) on the side surface of the ring bit (16),
The axial dimension (L1) of the ring bit (16) side recess (16C) is larger than the axial dimension (L2) of the engaging part (12B) of the casing shoe (12) (L1-L2 = δ: The play δ is preferably larger than the axial displacement (L3) of the ring bit (16) when the impact force is transmitted.

In this case, the corner (PP) in the cross-sectional shape of the polygonal (for example, hexagonal) pilot bit (15) is preferably provided at a position not overlapping the slime discharge slit (RR) (FIGS. 1 to 1). FIG. 15).
Alternatively, the corner (PP) in the cross-sectional shape of the polygonal (for example, hexagonal) pilot bit (15) is preferably provided at a position overlapping the slime discharge slit (RR) (FIG. 16).

According to the present invention having the above-described configuration, the cross-sectional shape of the pilot bit (15) is formed in a polygonal shape (for example, a hexagonal shape), and the cross-sectional shape of the inner wall surface (IS) of the ring bit (16) is the pilot bit ( 15) Since it is formed in a shape complementary to the cross-sectional shape of 15) (for example, a polygonal shape such as a hexagonal shape), at the time of excavation, if the pilot rod (15) is rotated by rotating the inner rod (13), The corner portion (PP) of the pilot bit (15) and the corner portion (PP-1) of the inner wall surface (IS) of the ring bit (16) whose cross-sectional shape is complementary to the pilot bit (15) are in contact with each other. (16) rotates reliably.
When the inner rod (13) is to be pulled up to the ground side, the inner rod (13) is pulled up to the ground side as it is, so that the cross-sectional shape of the inner wall surface (IS) of the ring bit (16) is the cross section of the pilot bit (15). Since it is complementary to the shape (for example, a polygonal shape such as a hexagon), the inner wall surface (IS) of the ring bit (16) does not interfere at all.

In the present invention, the cross-sectional shape of the pilot bit (15) and the inner wall surface (IS) of the ring bit (16) that is complementary thereto are polygonal (for example, hexagonal), but the cross-sectional shape has too many angles. When the rotational force is transmitted from the pilot bit (15) to the ring bit (16), the corner portion (PP-1) of the inner wall surface of the ring bit (16) complementary to the corner portion (PP) of the pilot bit (15). ) Do not come into contact with each other, and there is a risk that a so-called “tanned” state may occur. Further, if the number of corners of the cross-sectional shape is too large, there is a possibility that it is difficult to process the pilot bit (15) and the inner wall surface (IS) of the ring bit (16).
On the other hand, in the present invention, if the angle between the cross-sectional shape of the pilot bit and the cross-sectional shape of the inner wall surface of the ring bit is too small, the cross-sectional area of the pilot bit becomes small and the transmittable rotational force and impact force may be reduced. There is.
Therefore, in the present invention, when the rotational force is transmitted from the pilot bit (15) to the ring bit (16), the corner portion (PP) of the pilot bit (15) and the inner wall surface of the ring bit (16) having a complementary shape are formed. The corners (PP-1) are in contact with each other, and it is not difficult to process the pilot bit (15) and the inner wall surface (IS) of the ring bit (16). It is necessary to appropriately determine the number of corners of the pilot bit cross-sectional shape and the cross-sectional shape of the inner wall surface of the ring bit so that the impact force is not reduced. If the cross-sectional shape is, for example, a hexagon, the request can be met.

In this case, if the corner portion (PP) in the cross-sectional shape of the polygonal pilot bit (15) is provided at a position overlapping the slime discharge slit (RR), it is provided at a position not overlapping the slime discharge slit (RR). Compared to the case (FIG. 1 to FIG. 15), the leading striking force transmission region (β2: region indicated by hatching in FIG. 16) is larger, which is preferable in terms of striking force transmission.
However, the corner (PP) in the cross-sectional shape of the polygonal pilot bit (15) can be provided at a position that does not overlap the slime discharge slit (RR) (FIGS. 1 to 15).

According to the present invention, the thread of the threaded portion at the connection point between the inner rod (13) and the outer casing (11) can be in the same direction (for example, both are right-handed screws). Therefore, by connecting the boring machine (20) to the inner rod (13) and the outer casing (11), it is not necessary to rotate manually by the worker (M), and the inner rod (13) and the outer casing (11). Can be executed by the boring machine (20). The connection of the inner rod (13) and the connection of the outer casing (11) are performed by rotating with a boring machine (20). For example, the connection with the outer casing (11) is performed manually by a worker (M). The complicated work of final tightening with the breaker (α3) becomes unnecessary.
Moreover, since the direction of the screw | thread in the connection place of an inner rod (13) and an outer casing (11) can be made the same direction, a boring machine (20) in the case of excavation, and an outer casing (11) after excavation completion There is no need to prepare two types of boring machines that are used when removing the machine.
As a result, it can rotate in both the clockwise direction (the direction in which the right screw is tightened) and the counterclockwise direction (the direction in which the left screw is tightened), but an expensive and complicated structure boring machine needs to be used in the present invention. The inner rod (13) and the outer casing (11) can be connected / disconnected using a conventional general-purpose type boring machine (for example, a boring machine capable of rotating a rod or a casing only in a clockwise direction). I can do it. In other words, the screwing / unscrewing direction of the screw portion at the connection location of the outer casing 11 and the screwing / screwing release direction of the screw portion at the connection location of the inner rod 13 are opposite to each other. The resulting problems in the conventional double pipe drilling device can be solved by the present invention.

And according to this invention, since a boring machine (20) can be connected to an inner rod (13) and an outer casing (11), it is excavating by connecting slime discharge system piping to a boring machine (20). It is possible to transport the slime generated in the above to the slime treatment facility through the slime discharge system piping without being scattered around the excavation work site.
Therefore, it is possible to prevent contamination by the slime at the construction site by the double pipe drilling device, and improve the working environment.

In the present invention, a concave portion (16C) is formed on the side surface of the ring bit (16), and an engaging portion (12B) protruding radially inward is provided at the tip of the underground side of the canning shoe (12). The axial dimension of the ring bit side recess (16C) (the engaging portion (12B) at the tip of the L casing shoe (12) is engaged with the recess (16C) on the side of the ring bit (16). The axial dimension (L1) of the ring bit side recess (16C) is larger than the axial dimension (L2) of the engaging part (12B) of the casing shoe (12). A clearance (play δ: δ = L1-L2) corresponding to a dimension larger than the axial dimension (L2) of the engaging portion of (12) is a striking force generator (14: for example, down-the-hole hammer or ground-side drift Is much larger than the axial displacement (L3) of the ring bit (16) in the transmission of the striking force from the striking force type having a striking force generation mechanism), the pilot bit (15), the ring bit ( When a striking force is applied to 16), the striking force is not transmitted to the casing shoe (12) and not to the casing (11) due to the play (δ).
Therefore, even if the rotational force and the propulsive force are transmitted from the ground-side drifter (FIG. 1) to the casing, the impact from the impact force generator is not transmitted to the casing (11) by play (δ). This prevents the casing shoe (12) from being damaged.

Here, in the prior art, a double pipe excavation method (so-called “RPD”) in which both an inner rod and an outer casing are both moved in the ground and struck, and a striking force generator is provided on the ground side. "Construction method" exists. However, in such a prior art, the space | interval of a pilot bit and a ring bit (casing bit) is large (for example, about 10 mm). At the same time, since the underground tip portion of the inner rod is not coupled to the outer casing side, the inner rod is fixed only by the swivel joint of the boring machine (20), and therefore the amount of eccentricity due to the rod rotation is large.
On the other hand, according to the present invention, the cross-sectional shape of the pilot bit (15) and the inner wall surface (IS) of the ring bit (16) that is complementary to the cross-sectional shape are polygonal (for example, hexagonal). The gap between the cross-sectional shape of 15) and the inner wall surface (IS) of the ring bit (16) which is complementary to the cross-sectional shape can be reduced (for example, about 1 mm). Since the engagement portion (12B) at the tip of the casing shoe (12) is engaged with the recess (16C) on the side surface of the ring bit (16), the inner rod is connected to the swivel joint of the boring machine (20) and the tip. The pilot bit (15) and the ring bit (16) are fixed so that there is little eccentricity due to rotation. Therefore, in the present invention, compared to the above-described conventional technique (so-called “RPD” method), the straightness in excavation is better and the possibility of hole bending is reduced.

It is a cross-sectional view of the double pipe drilling device according to the first embodiment of the present invention. It is an expanded sectional view of the tip part of the double tube drilling device of a 1st embodiment. It is a cross-sectional view of a pilot bit used in the first embodiment. It is a figure which shows the AA 'cross section in the pilot bit of FIG. It is a figure which shows the BB 'cross section in the pilot bit of FIG. It is a figure which shows CC 'cross section in the pilot bit of FIG. It is a cross-sectional view of the ring bit used in the first embodiment. It is a figure which shows the AA 'cross section in the ring bit of FIG. It is a figure which shows the BB 'cross section in the ring bit of FIG. It is a figure which shows CC 'cross section in the ring bit of FIG. It is front sectional drawing for demonstrating the time of excavation of the double pipe drilling apparatus which concerns on 1st Embodiment. It is front sectional drawing which shows the connection operation | work of the inner rod and outer rod in the double pipe drilling apparatus which concerns on 1st Embodiment. It is a cross-sectional view of the casing shoe used in the first embodiment. FIG. 4 is a side view showing a portion where a striking force is transmitted to a ring bit in the pilot bit of FIG. 3. It is sectional drawing which shows the location which transmits the striking force in the pilot bit of FIG. It is sectional drawing which shows the location which transmits striking force to a ring bit in the pilot bit used by 2nd Embodiment. It is a perspective view which shows the front-end | tip part of the double pipe | tube drilling apparatus using the conventional down the hole hammer. It is front sectional drawing which shows the double pipe | tube drilling apparatus using the conventional down the hole hammer. It is front sectional drawing which shows the connection operation | work of the inner rod and outer rod in the double pipe | tube drilling apparatus of FIG.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
1 to 15 show a first embodiment of the present invention.
First, a double pipe drilling device 100 according to a first embodiment will be described with reference to FIGS. 1 and 2.
In the illustrated embodiment, a down-the-hole hammer 14 is used as a striking force generator.
1 (1) and (2) show a double pipe drilling device 100. FIG. Here, since the double-pipe drilling device 100 is a member that is long in the central axis direction, FIG. 1 is divided into (1) showing the structure on the ground side and (2) showing the structure of the tip on the ground side. It is expressed.

In FIG. 1A showing the configuration on the ground side, the ground side machine (20: boring machine), the swivel joint 30, the inner rod 13, and the outer casing 11 are shown. The swivel joint 30 also has a function of transmitting the rotational force and propulsive force of the boring machine 20 to the inner rod 13 and the outer casing 11.
On the other hand, in FIG. 1 (2) which shows the structure of the underground side, the equipment which continues to the underground side from the underground side end part (the right side of FIG. 1 (1)) of the inner rod 13 of FIG. A down-the-hole hammer 14, a pilot bit 15, a ring bit 16, an outer casing 11, and a casing shoe 12 that are disposed on the ground side from the inner rod 13 are shown.

Although not clearly illustrated, in the double-pipe drilling device 100 according to the first embodiment, the screw portion screwing / unscrewing direction at the connection portion of the outer casing 11 and the connection portion of the inner rod 13 are connected. The screwing / unscrewing direction of the screw portion is the same direction. For example, if the threaded portion at the connection location of the inner rod 13 is a right-hand thread, the threaded portion at the connection location of the outer casing 11 is also a right-hand thread.
The outer casing 11 is shown in both FIGS. 1 (1) and (2).
In FIGS. 1A and 1B, for the sake of simplification, the inner rod 13 and the outer casing 11 are connected one by one.

In FIG. 1 (1), the ground side machine (20: boring machine) has an inner box 21, and the female screw of the inner box 21 is connected to the ground side end of the inner rod 13 (the left end in FIG. 1 (1)). ) Is engaged with the inner rod 13 to engage with the inner rod 13 and move in the axial direction (direction of arrow F in FIG. 1 (1)) (propulsive force: feed) and rotational force ( The arrow R) in FIG.
The boring machine 20 has a casing pin 22, and the outer screw of the casing pin 22 is screwed to the female screw of the ground side end portion (the left end portion in FIG. 1 (1)) of the outer casing 11. Coupling with the casing 11, the outer casing 11 is subjected to axial movement (direction of arrow F in FIG. 1 (1)) (propulsive force: feed) and rotational force (arrow R in FIG. 1 (1)). Yes.
A swivel joint 30 is interposed between the boring machine 20 and the outer casing 11 and the inner rod 13. The swivel joint 30 has a structure as a fluid (water or air) supply system in addition to the joint function, and slime discharge after excavation. It has a structure as a system.

In FIG. 1 (2), the down-the-hole hammer 14 has its ground side end (left side in FIG. 1 (2)) connected to the underground side end of the inner rod 13 via a connecting member 14A. On the other hand, the vicinity of the tip of the down-the-hole hammer 14 on the ground side (right side in FIG. 1 (2)) is connected to the pilot bit 15, and the pilot bit 15 is connected to the ring bit 16.
The down-the-hole hammer 14 has a function of imparting striking force to the pilot bit 15 and the ring bit 16.
An outer casing 11 and a casing shoe 12 are disposed outside the inner rod 13, the down-the-hole hammer 14, the pilot bit 15 and the ring bit 16 in the radial direction. The casing shoe 12 is connected to the outer casing 11 and is provided in the vicinity of the end on the ground side of the outer casing 11.

When excavating with the double-pipe drilling apparatus 100 configured as described above, rotational force and propulsive force are applied from the boring machine 20 to the inner rod 13, the pilot bit 15, and the ring bit 16. At the same time, a rotational force and a propulsive force are applied from the boring machine 20 to the outer casing 11. Further, the down-the-hole hammer 14 applies a striking force to the pilot bit 15 and the ring bit 16.
The pilot bit 15 and the ring bit 16 perform excavation while digging in the ground with the rotational force and the striking force. At the same time, rotational force and propulsive force are also applied to the outer casing 11, and the outer casing 11 travels underground.
Here, since the down-the-hole hammer 14 that generates a striking force is located near the tip on the ground side, noise due to the striking force is attenuated before reaching the ground side. For this reason, the environment around the work site is prevented from deteriorating due to the noise caused by the impact force.

The swivel joint 30 has a function of supplying drilling liquid (water or air: or a driving fluid for the down-the-hole hammer 14) and a slime discharging function after drilling.
In FIGS. 1 (1) and (2), a drilling fluid supplied from a drilling fluid source (not shown) is supplied from a drilling fluid intake 31 provided on the upper surface of the swivel joint 30, and via a passage 32 in the swivel joint. It passes through a drilling fluid passage (not shown) provided in the inner rod 13, down-the-hole hammer 14, and pilot bit 15 and excavates from a drilling fluid injection port (not shown) provided at the tip of the pilot bit 15. It is injected toward the ground.
The flow from when the drilling fluid is supplied from the drilling fluid intake port 31 until the drilling fluid is injected from the drilling fluid injection port is indicated by an arrow W1 in FIG.
As described above, the drilling fluid is jetted toward the ground from the drilling fluid jet port, and is also used as a drive source (power fluid) for the down-the-hole hammer 14.

Slime (mixed fluid of excavated earth and sand, gravel, and drilling fluid) generated when the ground is excavated by jetting the drilling fluid is a slime provided at the tip of the pilot bit 15 and in the vicinity of the boundary with the ring bit 16 It flows into the double-pipe drilling device 100 from the intake (not shown), passes through the slime discharge slit RR (see FIGS. 4 to 6) formed in the pilot bit 15, and the down-the-hole hammer 14 and the inner rod 13. And a slime discharge passage (not shown) formed between the outer casing 11 and the outer casing 11 (partly casing shoe 12).
Then, it is discharged out of the double-pipe drilling device 100 from the slime discharge port 34 provided on the upper surface of the swivel joint 30 through the passage 33 in the swivel joint.

In FIG. 1, the flow until the slime flows in from the slime intake port and is discharged from the slime discharge port 34 is indicated by an arrow W2.
Although not clearly shown, if a slime carrying pipe (not shown) communicating from the slime outlet 34 to a slime storage device (not shown) is provided, the working environment around the double-pipe drilling device 100 can be maintained well. I can do it.

In FIG. 2 showing details of the vicinity of the underground tip of the double pipe drilling device 100, a pilot bit 15 (see FIGS. 3 to 6) connected to the down-the-hole hammer 14 is provided, and the radius of the pilot bit 15 is provided. Outside the direction, the ring bit 16 (see FIGS. 7 to 10) is arranged so as to surround the underground region (right side in FIG. 2) of the pilot bit 15.
A casing shoe 12 (see FIG. 13) is disposed radially outward of the ring bit 16, and as described above with reference to FIG. Thus, the outer casing 11 is connected by the screw portion 12C.
A concave portion 16 </ b> C is formed on the side surface of the ring bit 16, and an engaging portion 12 </ b> B protruding radially inward is formed at the ground-side tip of the canning shoe 12. The engaging portion 12B at the tip of the casing shoe 12 is engaged with the concave portion 16C on the side surface of the ring bit 16, so that the ring bit 16 and the canning shoe 12 are engaged.

Here, the axial dimension L1 of the recess 16C on the side surface of the ring bit 16 is set to be larger than the axial dimension L2 of the engaging portion 12B of the casing shoe 12.
Assuming that “L1−L2 = δ”, the ring bit 16 side surface recessed portion 16C has a so-called “play” with an axial dimension δ with respect to the engaging portion 12B of the casing shoe 12 (in this specification, such play is referred to as “play”). may be written as “δ”).
The play δ is set to be much larger than the axial displacement L3 of the ring bit 16 when the striking force is transmitted from the down-the-hole hammer 14 (not shown in FIG. 2).

A plurality of chips 15 </ b> B are provided at a tip end portion (right end portion in FIG. 2) on the underground side of the pilot bit 15. The tip 15B is provided for excavating the soil effectively by transmitting the striking force from the down-the-hole hammer 14 while the pilot bit 15 rotates.
On the other hand, a tip 16 </ b> D similar to the pilot bit 15 is also provided at the tip of the ring bit 16 on the ground side (the right end in FIG. 2). The tip 16D also has an action of effectively excavating the soil in cooperation with the tip 15B of the pilot bit 15 during excavation.

The cross-sectional shape of the pilot bit 15 used in the first embodiment is shown in FIGS. 3 to 6, three slime discharge slits RR are formed on the side surface of the pilot bit 15 at equal intervals in the circumferential direction.
The cross-sectional shape in the vicinity of the tip of the pilot bit 15 is shown in FIG. 6 (cross-sectional view taken along the line CC ′ in FIG. 3), but the portion other than the tip of the pilot bit 15 (on the left side of CC ′ in FIG. As shown in FIGS. 4 and 5, the cross-sectional shape of the portion) is formed in a substantially hexagonal shape excluding the slime discharge slit RR.
On the other hand, in FIGS. 7 to 10 showing the cross-sectional shape of the ring bit 16 used in the first embodiment, the ring bit 16 has an inner wall surface IS (FIGS. 8 to 10) located on the radially outer side of the pilot bit 15. I have. The cross-sectional shape of the inner wall surface IS of the ring bit 16 is as shown in FIG. As shown in FIG. 9, it is formed in a hexagonal shape.

In other words, the cross-sectional shape of the pilot bit 15 (see FIGS. 4 and 5) and the cross-sectional shape of the inner wall surface IS of the ring bit 16 (see FIGS. 8 and 9) are both hexagonal, so-called “complementary” shapes. It has become.
Since the cross-sectional shape of the pilot bit 15 (see FIGS. 4 and 5) and the cross-sectional shape of the inner surface IS of the ring bit 16 (see FIGS. 8 and 9) are both hexagonal and complementary, When the inner rod 13 rotates and the pilot bit 15 rotates due to the rotational force applied from the boring machine 20, the corner portion PP of the pilot bit 15 and the corner portion PP-1 of the inner wall surface IS of the ring bit 16 come into contact with each other. As a result, the ring bit 16 rotates reliably.

Connection and disconnection of the inner rod 13 and the outer casing 11 in the double-pipe drilling device 100 according to the first embodiment will be described with reference to FIGS. 11 and 12.
As described above, in the double-pipe drilling device according to the first embodiment, the screwing / unscrewing direction of the screw part at the connection point of the outer casing 11 and the screwing of the screw part at the connection point of the inner rod 13 are performed. / The screw release direction is the same direction. For example, if the threaded portion at the connection location of the inner rod 13 is a right-hand thread, the threaded portion at the connection location of the outer casing 11 is also a right-hand thread.

In FIG. 11, the boring machine 20 is engaged with both the outer casing 11 and the inner rod 13, and can rotate the outer casing 11 and the inner rod 13 in the direction in which the right screw is tightened (clockwise).
Since the outer casing 11 is connected to the boring machine 20, in FIG. 11, the annular space (annular space between the outer casing 11 and the inner rod 13) through which the slime SL (FIG. 18) generated during excavation flows is bored. It communicates with the machine 20. As described above, the slime SL has a double-pipe drilling device from the slime outlet 34 provided on the upper surface of the swivel joint 30 through the passage 33 in the swivel joint, as described in FIG. It is discharged out of 100. Therefore, the slime is not scattered on the excavation work site, and the work site environment is improved.

When excavation progresses and the outer casing 11 and the inner rod 13 are to be connected, in the state shown in FIG. 11, a worker M (see FIG. 19: not shown in FIGS. 11 and 12) is to be connected. The heavy pipe (the outer casing 11 and the inner rod 13) is arranged on the already connected double pipe. Then, the outer casing 11 is lifted by the worker M, the inner rod 13 is held by the clamp α2, and the box 21 of the boring machine 20 is screwed to the ground side end of the new inner rod 13 to be connected. Thus, the inner rod 13 is rotated in the clockwise direction (the direction in which the right screw is tightened) to connect the inner rod 13.
When the connection of the inner rod 13 is completed, the holding of the inner rod 13 by the clamp α2 is released, the outer casing 11 is placed on the preceding outer casing 11, and the outer casing 11 is held by the clamp α1 (FIG. 12). .

Then, the outer casing 11 to be connected (upper casing in FIG. 12) is rotated clockwise (in the direction in which the right screw is tightened) by the boring machine 20 and connected to the outer casing 1 held by the clamp α1.
When the outer casing 11 shown in FIG. 12 is connected, it is not necessary to rotate a new casing manually by the worker M, and it is not necessary to finally rotate and tighten the outer casing 11 by the clamp α3 (breaker). .
As described above, in the double pipe drilling device according to the first embodiment, when the excavation progresses and the double pipe is connected, the outer casing 11 can be connected by the boring machine 20. The labor and cost in the connecting work are greatly reduced as compared with the connecting work in the conventional double pipe drilling device described with reference to FIGS.

Although not shown, in the double-pipe drilling device of the first embodiment, the direction in which the inner rod 13 is connected and the direction in which the outer casing 11 is connected are the same direction. 13. In order to extubate the outer casing 11, it is only necessary to loosen the screw using a clamp α 3 (breaker). The inner rod 13 and the outer casing 11 can be extracted without preparing a boring machine that rotates in the opposite direction to the boring machine 20 for excavation.
Therefore, it is not necessary to prepare two types of boring machines, and it is not necessary to replace the boring machines for each type of work.

In addition to this, when it is desired to lift the inner rod 13 to the ground side with respect to the outer casing 11, the inner rod 13 may be lifted to the ground side as it is.
Since the inner wall surface IS of the ring bit 16 and the cross-sectional shape (hexagonal shape) of the pilot bit 15 are complementary shapes, the pilot bit 15 interferes with the inner wall surface IS of the ring bit 16 when the inner rod 13 is pulled up to the ground side. This is because the inner rod 13 connected to the pilot bit 15 can be easily pulled out.
Thereafter, when returning the pilot bit 15 at the tip of the inner rod 11 to the ground side again, the pilot bit 15 may be inserted into the inner wall surface IS of the ring bit 16.

Here, the reason why the cross-sectional shape of the pilot bit 15 and the inner wall surface IS of the ring bit 16 that is complementary thereto is hexagonal is as follows.
If the cross-sectional shape of the pilot bit 15 and the cross-sectional shape of the inner surface IS of the ring bit 16 that is complementary to the pilot bit 15 are made octagonal or larger, the internal angle at each corner becomes an angle close to 180 ° (large angle). Therefore, when the rotational force is transmitted from the pilot bit 15 to the ring bit 16, the corner PP of the pilot bit 15 and the corner PP-1 of the inner wall surface IS70 of the complementary shape of the ring bit 16 slip, so-called “tanned”. It becomes difficult to transmit the rotational force. Further, if the cross-sectional shape is an octagon or more, it is difficult to process the pilot bit 15 and the inner wall surface IS of the ring bit 16.
On the other hand, if the cross-sectional shape of the inner wall surface IS of the pilot bit 15 and the ring bit 16 is triangular to pentagonal, the cross-sectional area of the pilot bit 15 is reduced, and the rotational force and striking force that can be transmitted to the pilot bit 15 and the ring bit 16 are reduced. End up.
However, the illustrated embodiment can be implemented even if the cross-sectional shape is a polygonal shape other than a hexagonal shape (polygonal shape of a triangle or more).

In FIG. 13, an engaging portion 12 </ b> B that protrudes inward in the radial direction is formed at the tip of the canning shoe 12 (the end on the ground side: the right end in FIG. 13).
As described with reference to FIG. 2, the recess 16C is formed on the side surface of the ring bit 16, and the engagement portion 12B at the tip of the casing shoe 12 engages with the recess 16C on the side surface of the ring bit 16. And the ring bit 16 are engaged.
In FIG. 13, reference numeral 12 </ b> C is a screw portion for coupling the casing shoe 12 and the outer casing 11.

As described above with reference to FIG. 2, the play δ, which is the difference between the axial dimension L1 of the recess 16C on the side surface of the ring bit 16 and the axial dimension L2 of the engaging portion 12B of the casing shoe 12, is from the down-the-hole hammer 14. It is much larger than the axial displacement L3 of the ring bit 16 when the impact force is transmitted. Therefore, when a striking force is applied to the pilot bit 15 and the ring bit 16 from the down-the-hole hammer 14 (not shown in FIG. 2), such play δ exists, so that the striking force is not transmitted to the casing shoe 12. Also, it is not transmitted to the outer casing 11.
Therefore, even if rotational force and propulsive force are transmitted from the ground-side boring machine 20 (see FIG. 1 (1)) to the outer casing 11, the striking force from the down-the-hole hammer 14 is not transmitted to the outer casing 11 due to play δ. Therefore, the outer casing 11 is prevented from being damaged by the impact force.

FIG. 14 shows the location where the striking force transmitted from the down-the-hole hammer 14 to the pilot bit 15 is transmitted to the ring bit 16. In FIG. 14, hitting force is applied by the hatched portions β <b> 1 and γ <b> 1 coming into contact with the ring bit 16.
As shown in FIG. 14, the position of the region β <b> 1 in the axial direction is the bottom side of the pilot bit 15, and is the ground side end (left side in FIG. 2) of the ring bit 16.
As is clear from FIG. 14, the region indicated by the symbol β1 (region on the bottom side of the pilot bit 15) is the region indicated by the symbol γ1 (the region on the tip side of the pilot bit 15: a secondary region for transmitting impact force). It is large in comparison and plays a leading role in the transmission of impact power.

15 shows hatching positions on the plane of the hit transmission region β1 (leading hitting force transfer region β1: the bottom side of the pilot bit 15) in the first embodiment of FIGS. Is shown.
As described above, since the cross-sectional shape of the pilot bit 15 (except for the slime discharge slit RR) is formed in a substantially hexagonal shape, the pilot bit 15 is shown in a hexagonal shape in FIG. In FIG. 15, the corners (hexagonal corners) of the pilot bit 15 are indicated by the symbol PP.
In FIG. 15, in the first embodiment, the slime discharge slit RR of the pilot bit 15 is formed at a position that does not overlap the corner portion PP of the pilot bit 15.

In FIG. 15, the striking force transmission region β1 formed in the pilot bit 15 (leading striking force transmission region β1: a region on the bottom side of the pilot bit 15 in the pilot bit 15) is three at equal intervals in the circumferential direction. Is formed. In other words, in FIG. 15, the three striking force transmission regions β1 are regions between the adjacent corner portions PP in the pilot bit 15 and are on the side where the slime discharge slit RR in the hexagon is not provided. Is provided.
The striking force transmission region β1 is formed in an arc shape that swells outward in the radial direction.
By securing the striking force transmission region β1 (leading striking force transmission region β1: the region on the bottom side of the pilot bit 15 in the pilot bit 15), the striking force generated by the down-the-hole hammer 14 is transmitted via the pilot bit 15. It is reliably transmitted to the ring bit 16.

On the other hand, in the second embodiment of FIG. 16, the three corner portions PP in the cross-sectional shape of the pilot bit 15 are configured to overlap with the slime discharge slit RR.
Therefore, in the second embodiment of FIG. 16, the striking force transmission region β2 (the region indicated by hatching in FIG. 16) is formed on all sides between the adjacent corners PP in the pilot bit 15, The force transmission region β2 is formed in an arc shape that swells outward in the radial direction. However, the striking force transmission regions β2 are not formed in the three slime discharge slits RR.
In the second embodiment of FIG. 16, the striking force transmission region β2 in FIG. 16 is configured to overlap the region β1 in FIG. 15 by configuring the corner PP in the cross-sectional shape of the pilot bit 15 to overlap the slime discharge slit RR. It is configured to have a much larger area than
According to the inventor's experiment, the region β2 in FIG. 16 is about twice the region β1 in FIG.

Here, the secondary region γ1 of the impact force transmission shown in FIG. 14 is not shown, but is smaller in the second embodiment of FIG. However, as described above, the region γ1 (FIG. 14) has a secondary role in the transmission of the striking force.
And about the sum total of leading area | region (beta) 1, (beta) 2 of impact power transmission, and secondary area | region (gamma) 1, 2nd Embodiment of FIG. 16 is about 1.5 times of 1st Embodiment of FIGS. It has been clarified through experiments by the inventors.
Other configurations and operational effects in the second embodiment of FIG. 16 are the same as those of the first embodiment of FIGS.

It should be noted that the illustrated embodiment is merely an example, and is not a description to limit the technical scope of the present invention.
For example, in the illustrated embodiment, a down-the-hole hammer is illustrated as a striking force generator, but it is also possible to use a drifter that is a ground-side drifter and has a striking force generation mechanism as the striking force generator. .
In the illustrated embodiment, the inner surface 1S of the pilot bit 15 and the ring bit 16 having a hexagonal cross-sectional shape is shown. However, the cross-sectional shapes of the pilot bit 15 and the inner wall surface 1S of the ring bit 16 are other than hexagonal. It is also possible to have a polygonal shape (polygonal shape that is greater than or equal to a triangle).

DESCRIPTION OF SYMBOLS 11 ... Outer casing 12 ... Casing shoe 12A ... Engaging convex part 12B ... Engaging part 12C ... Screw part 13 ... Inner rod 14 ... Down the hole hammer 15 ... Pilot Bit 15A ... engagement piece 15B ... tip 16 ... ring bit 16A ... engagement groove 16B ... annular groove 16C ... recess 16D ... tip 20 ... boring machine 21 .... Inner box 22 ... Casing pin 30 ... Swivel joint 31 ... Drilling fluid intake 32, 33 ... Swivel joint passage 34 ... Slime discharge port 100 ... Double pipe drilling apparatus

Claims (4)

It has an inner rod and an outer casing connected to the ground side machine, a pilot bit is connected to the underground side of the inner rod, a ring bit is arranged radially outward of the pilot bit, and the tip of the outer casing A casing shoe is connected to each other, the cross-sectional shape of the pilot bit is formed in a polygonal shape, and the cross-sectional shape of the inner wall surface of the ring bit is formed in a shape complementary to the face shape of the pilot bit. Heavy pipe drilling device. The pilot bit is formed with a region for transmitting the striking force from the striking force generator to the ring bit, a concave portion is formed on the side surface of the ring bit, and the tip of the canning shoe is radially inward. An engagement portion protruding in the direction is formed, and the engagement portion at the tip of the casing shoe is engaged with the concave portion on the side surface of the ring bit, and the axial dimension of the concave portion on the side surface of the ring bit is determined by the engagement of the casing shoe. The double-pipe drilling device according to claim 1, which is larger than the axial dimension of the portion. The double-pipe drilling device according to claim 2, wherein corner portions of the cross-sectional shape of the polygonal pilot bit are provided at positions that do not overlap the slime discharge slit. The double-pipe drilling device according to claim 2, wherein a corner portion in a cross-sectional shape of the polygonal pilot bit is provided at a position overlapping the slime discharge slit.

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