KR20150110997A - Drilling bit - Google Patents

Abstract

The present invention relates to a drilling bit capable of easily installing a steel pipe by using a wing bit which can be folded. The drilling bit includes: a bit body having a cutting edge excavation surface on one side and a guide groove on the other side; the wing bit having a shaft protrusion, which can be guided along the guide groove of the bit body, on one side or both sides and rotating around the shaft protrusion guided along the guide groove by being assembled with the bit body; a stopper member installed in the bit body to prevent the shaft protrusion from being separated from the guide groove; and a wing bit fixing device installed in the bit body and/or the stopper member and fixing the wing bit so that the wing bit can be fixed in a state that the wing bit is pivoted and spread in a moving direction.

Description

Drilling bit

The present invention relates to a drilling bit, and more particularly, to a drilling bit capable of facilitating installation of a steel pipe using a wing bit capable of folding.

Generally, the steel pipe grouting method is an underground excavation assist method that improves the water quality while reinforcing the ground. By installing the steel pipe on the ground and injecting the grout material into the inside of the steel pipe, the steel pipe and the ground are integrally It is characterized by increasing the soil and the shear strength of the rock mass. It is very advantageous in terms of workability and economical efficiency because the injection is performed in the steel pipe.

Such a steel pipe grouting method has been established and widely used as a tunnel reinforcement method in recognition of its effect.

Generally, the steel pipe grouting method includes a step of drilling a ground, a step of inserting a steel pipe provided with a strainer (grout reinjecting part) into the perforated hole, a step of injecting a sealing material between the steel pipe and the perforation hole, While injecting cement.

However, since this method proceeds by inserting the steel pipe after the perforation, there is a problem that it is difficult to insert the steel pipe due to collapse of the perforation hole or mixing of foreign materials in the soft soil layer where the perforation hole is not naturally maintained.

In order to solve the above problems, a technique has been developed in which a steel pipe can be easily installed using a foldable wing bit as disclosed in Korean Patent Registration No. 100919628.

However, such a conventional foldable wing bit is a separate component in which the wing bit and the pin are separated from each other by hinging the wing bit to the bit body by assembling the pin, which is a separate component from the bit body, There is a serious problem that the wing bit and the pin are finely collided with each other due to the great external force and impact generated in the excavation process and the gap is widened or the wing bit or pin is broken.

Since the pin is assembled through the bit body, a part of the pin is exposed, and various foreign substances can easily penetrate between the pin and the gap of the bit body caused by a great external force and impact generated during the excavation process. There is a problem in that the durability becomes very weak such as interfering with the folding or even detaching the pin from the bit body.

In addition, the conventional pins are coupled to the bit body in a deteriorated manner, so that it is very difficult to separate the wing bits in order to repair or replace the wing bits.

In addition, the conventional wing bit can maintain the unfolded state when advancing toward the excavation progressing direction, but on the contrary, when the wing bit is retracted, the wing bit is easily folded again by gravity or external force. However, There was a problem that it could not be used in the work or an incidental work.

In order to solve such a conventional problem, the present invention is capable of selectively fixing the angle of the wing bit selectively by only twisting operation, so that the wing bit is unfolded to move the steel pipe in a fixed state, It is resistant to external force and impact, and the shaft protrusion is not exposed to the outside of the bit body. Therefore, the wing bit is prevented from escaping and the durability is improved remarkably. It is an object of the present invention to provide a drilling bit that facilitates repair and replacement of a wing bit by using a detachable stopper member. However, these problems are exemplary and do not limit the scope of the present invention.

According to an aspect of the present invention, there is provided a drilling bit comprising: a bit body having an advanced excavation surface formed on one side and a guide groove formed on the other side; A wing bit which is formed on one side or both sides of the shaft body and which can be guided along the guide groove of the bit body and which can be assembled with the bit body about the axis projection guided along the guide groove and pivotable; A stopper member provided on the bit body such that the shaft protrusion is not separated from the guide groove; And a wing bit fixing device installed on the bit body and / or the stopper member and fixing the wing bit so that the wing bit is rotated and fixed in a state in which the wing bit is pivoted on the basis of the traveling direction.

According to an aspect of the present invention, the wing bit fixing device further includes: a binding bar which can be selectively engaged with a bite formed in one side of the wing bit in an unfolded state; And a engagement rod forward and backward device capable of advancing and retracting said engagement rod in said engagement groove direction.

According to an aspect of the present invention, the engagement bar forward / backward device further includes: an inner barrel provided on the bit body and having a sliding groove formed on an outer diameter surface to guide the engagement bar forward and backward; A cam protrusion provided outside the engaging bar; And an outer cylinder receiving the inner cylinder and the engagement rod therein and having a cam groove formed on an inner diameter surface of the inner diameter face so as to be sloped with respect to the advancing direction so as to guide the cam protrusion.

According to an aspect of the present invention, when the outer cylinder is twisted in the forward direction with respect to the inner cylinder as a reference, the cam protrusion moves forward and backward so that the cam protrusion moves together with the cam protrusion, A moving slope section, and a backward horizontal section.

According to an aspect of the present invention, the inner tube is integrally formed with the bit body, the stopper member is formed integrally with the outer tube, and the outer tube is rotatably supported by the outer tube so that the inner tube is rotatably supported on the outer tube. And a separation preventing pin passing through the peripheral groove formed in the inner cylinder.

According to an aspect of the present invention, the bit body and the inner cylinder are provided with a working fluid injection hole at a central shaft portion, a first working fluid discharge groove formed at an outer surface of the bit body, A second working fluid discharge groove is formed in a side surface of the outer cylinder so that the second working fluid discharge groove is formed on the outer surface of the outer cylinder so as to be aligned in series with the first working fluid discharge groove when the outer cylinder is twisted in the forward direction .

According to an aspect of the present invention, the wing bit fixing device further includes: a rack gear engaged with gear teeth formed on one side of the wing bit in an unfolded state; And a rack gear forward / backward device capable of advancing and retracting the rack gear.

According to an aspect of the present invention, the wing bit fixing device further includes: a contact bar capable of selectively contacting a plane of the wing bit in an unfolded state; And a contact bar forward / backward device capable of advancing and retracting the contact bar in the planar direction.

According to an aspect of the present invention, the bit body is formed with a wing bit accommodating groove having a shape corresponding to a part of the wing bit on one side thereof, and the guide groove is formed on the inner wall face of the wing bit accommodating groove, As shown in Fig.

According to an aspect of the present invention, the wing bit is formed with axle protrusions on both sides thereof, a wing bit excavation surface facing forward and / or sideways is formed in a state in which the wing bit is rotated and unfolded, And a carbide tip may be installed on the wing bit excavation surface.

According to an aspect of the present invention, the bit body has the tip excavated surface formed at its tip end, the guide groove facing the direction of the traveling direction is formed in the middle, and the bit body can be easily assembled A screw protrusion may be provided at the rear end.

According to some embodiments of the present invention as described above, the angle of the wing bit can be selectively fixed to move the steel pipe, perform other excavation work, or can be utilized in an incidental work, And the wing bit is prevented from departing, thereby remarkably improving the durability, accuracy, reliability and performance of the apparatus, facilitating repair and replacement of the wing bit, and facilitating management of the apparatus. Of course, the scope of the present invention is not limited by these effects.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a part exploded perspective view of a drill bit according to some embodiments of the present invention.
Fig. 2 is a part exploded rear perspective view showing the excavating bit of Fig. 1; Fig.
3 is a cross-sectional perspective view showing an outer tube of the excavating bit shown in Fig.
4 is a perspective view showing the bit body of the excavating bit of FIG.
5 is a rear perspective view showing the bit body of the excavating bit of FIG.
Fig. 6 is a perspective view of the wing bit folded state of the drilling bit of Fig. 1 in use; Fig.
Fig. 7 is a perspective view of the used wing bit in the use state of the excavating bit of Fig. 6; Fig.
FIG. 8 is a perspective view of the used wing bit fixed state of the excavating bit of FIG. 7 in use; FIG.
Fig. 9 is a rear perspective view showing the advancing state of the engagement bar in Fig. 8; Fig.
10 is a rear perspective view showing the retracted state of the engagement bar in Fig.
Figs. 11 and 12 are perspective views step-wise showing wing bits and engagement bars according to some embodiments of Fig.
Figs. 13 and 14 are perspective views that step-wise illustrate wing bits and engagement bars in accordance with some other embodiments.
Figs. 15 and 16 are perspective views step-wise showing wing bits and rack gears according to some further embodiments. Fig.
Figures 17 and 18 are perspective views that step through the wing bit and contact bar in accordance with some further embodiments.
19 is a part exploded perspective view showing a drill bit according to some embodiments of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention are described in order to more fully explain the present invention to those skilled in the art, and the following embodiments may be modified in various other forms, The present invention is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be more thorough and complete, and will fully convey the concept of the invention to those skilled in the art. In the drawings, the thickness and size of each layer are exaggerated for convenience and clarity of explanation.

It is to be understood that throughout the specification, when an element such as a film, region or substrate is referred to as being "on", "connected to", "laminated" or "coupled to" another element, It will be appreciated that elements may be directly "on", "connected", "laminated" or "coupled" to another element, or there may be other elements intervening therebetween. On the other hand, when one element is referred to as being "directly on", "directly connected", or "directly coupled" to another element, it is interpreted that there are no other components intervening therebetween do. Like numbers refer to like elements. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items.

Although the terms first, second, etc. are used herein to describe various elements, components, regions, layers and / or portions, these members, components, regions, layers and / It is obvious that no. These terms are only used to distinguish one member, component, region, layer or section from another region, layer or section. Thus, a first member, component, region, layer or section described below may refer to a second member, component, region, layer or section without departing from the teachings of the present invention.

Also, relative terms such as "top" or "above" and "under" or "below" can be used herein to describe the relationship of certain elements to other elements as illustrated in the Figures. Relative terms are intended to include different orientations of the device in addition to those depicted in the Figures. For example, in the figures the elements are turned over so that the elements depicted as being on the top surface of the other elements are oriented on the bottom surface of the other elements. Thus, the example "top" may include both "under" and "top" directions depending on the particular orientation of the figure. If the elements are oriented in different directions (rotated 90 degrees with respect to the other direction), the relative descriptions used herein can be interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" include singular forms unless the context clearly dictates otherwise. Also, " comprise "and / or" comprising "when used herein should be interpreted as specifying the presence of stated shapes, numbers, steps, operations, elements, elements, and / And does not preclude the presence or addition of one or more other features, integers, operations, elements, elements, and / or groups.

Hereinafter, embodiments of the present invention will be described with reference to the drawings schematically showing ideal embodiments of the present invention. In the figures, for example, variations in the shape shown may be expected, depending on manufacturing techniques and / or tolerances. Accordingly, the embodiments of the present invention should not be construed as limited to the particular shapes of the regions shown herein, but should include, for example, changes in shape resulting from manufacturing.

1 is a part exploded perspective view showing a drill bit 100 in accordance with some embodiments of the present invention. 3 is a cross-sectional perspective view showing an outer cylinder 45 of the excavating bit 100 of FIG. 1, and FIG. 4 is a cross-sectional perspective view of the excavating bit 100 of FIG. 1, And FIG. 5 is a rear perspective view showing the bit body 10 of the excavating bit 100 of FIG. 4. FIG. 5 is a perspective view showing the bit body 10 of the excavating bit 100 of FIG.

1 to 5, a drilling bit 100 according to some embodiments of the present invention includes a bit body 10, a wing bit 20, a stopper member 30, And a wing bit fixing device 40. [

4 and 5, the bit body 10 is a kind of metal block having an advanced excavation surface 10a formed on one side thereof and a guide groove GD formed on the other side thereof, A wing bit accommodating groove 11 having a shape corresponding to a part of the wing bit 20 is formed and the guide groove GD is formed on an inner wall face of the wing bit accommodating groove 11 in a direction opposite to the advancing direction .

1 and 2, the wing bit 20 is formed such that an axial projection 21 that can be guided along a guide groove GD of the bit body 10 is formed on one side or both sides And may be a kind of metal block which can be assembled with the bit body 10 and pivoted about the axis projection 21 guided along the guide groove GD.

More specifically, for example, as shown in FIGS. 1 and 2, the wing bit 20 has axle protrusions 21 formed on both sides thereof, and the wing bit 20 is rotated and unfolded A wing bit excavation surface 20a facing forward and / or laterally is formed and a carbide tip T can be installed on the advanced excavation surface 10a and the wing bit excavation surface 20a.

The stopper member 30 is installed on the bit body 10 so that the shaft protrusion 21 is not separated from the guide groove GD and may be integrally formed with the outer cylinder 45 have.

1 to 3, the wing bit fixing device 40 is installed on the bit body 10 and / or the stopper member 30, and the wing bit 20 is rotated And fix the wing bit 20 so that the wing bit 20 can be fixed in a spread state based on the traveling direction.

1 and 2, the wing bit fixing device 40 is configured to selectively engage the engaging groove 22 formed at one side of the wing bit 20 in the unfolded state, for example, And a locking bar forward and backward device 42 which can advance and retract the locking bar 41 in the direction of the bite groove 22.

1 and 2, the engaging bar forward / backward device 42 is provided on the bit body 10, and is capable of guiding the engaging bar 41 in the forward / The inner barrel 43 in which the sliding groove SG is formed and the cam protrusion 44 provided on the outside of the engaging bar 41 and the inner barrel 43 and the engaging bar 41, And an outer cylinder 45 having an inner diameter surface formed with a cam groove 46 formed to be inclined with respect to the advancing direction so as to guide the cam protrusion 44. [

3, when the outer cylinder 45 is twisted in the forward direction with respect to the inner cylinder 43, the cam protrusion 44 moves along the cam groove 46, A forward slope section 46-2 and a backward slope section 46-3 so that the engaging rod 41 can be moved forward or backward together with the cam protrusion 44. [ have.

1 and 2, the inner tube 43 is integral with the bit body 10, and the stopper member 30 can be formed integrally with the outer tube 45.

1 and 2, the excavating bit 100 according to some embodiments of the present invention may be configured such that the inner tube 43 is rotatably supported on the outer tube 45 in a twisted manner (50) passing through the outer cylinder (45) and passing through the peripheral groove (43a) formed in the inner cylinder (43).

Therefore, the inner cylinder 43 and the outer cylinder 45 can be assembled to each other by using the separation prevention pin 50, and the assembled outer cylinder 45 is prevented from being caught by the inner cylinder 43 , And can be twisted freely with respect to the inner tube 43 as a reference.

6 is a perspective view of the used wing bit 20 of the drilling bit 100 of FIG. 1 in a used state showing the folded state of the wing bit 20, and FIG. And FIG. 8 is a perspective view of a used state showing the assembled wing bit 20 of the excavating bit 100 of FIG. 7 in a fixed state.

9 is a rear perspective view showing the advancing state of the engagement bar 41 shown in Fig. 8, and Fig. 10 is a rear perspective view showing the retreated state of the engagement bar 41 shown in Fig.

6 to 8, the operation of the excavation bit 100 according to some embodiments of the present invention described above will be described. First, as shown in FIG. 6, When the shaft protrusion 21 of the stopper member 20 is completely inserted into the guide groove GD and is twisted together with the stopper member 30 using the release prevention pin 50, The stopper 30 closes the inlet of the guide groove GD so that the wing bit 20 can be folded without being detached from the bit body 10. [

Then, as shown in Fig. 7, the wing bit 20 can be unfolded naturally by an external force when the user unfolds or excavates by hand.

At this time, as shown in FIG. 10, the wing bit 20 can be freely rotated without being constrained by the bit body 10 because the engaging rod 41 is in a retracted state. Here, the cam protrusion 44 may be located in the backward horizontal section 46-3 of the cam groove 46. [

At this time, the backward horizontal section 46-1 serves to prevent the cam protrusion 44 from entering the moving ramp section 46-2 by twisting the cam groove 46 more twistedly .

8, when the bit body 10, that is, the stopper member 30, that is, the outer tube 45 is twisted with respect to the inner tube 43, as shown in Fig. 9 Similarly, the locking bar 41 may be advanced and inserted into the bite groove 22 formed in the wing bit 20.

At this time, when the engaging rod 41 is inserted into the engaging groove 22, the rotation of the wing bit 20 is not free. Therefore, the wing bit 20 is inserted into the bit body 10 in the unfolded state And can be firmly fixed and fixed.

Here, the cam protrusion 44 may be positioned along the forward slope section 46-2 of the cam groove 46 and finally in the forward horizontal section 46-1.

At this time, the forward horizontal section 46-1 serves to further twist the cam groove 46 to prevent the cam protrusion 44 from re-entering the moving ramp section 46-2 again .

The bit body 10 and the inner tube 43 are each formed with a working fluid injection hole G1 at a central shaft portion and a first working fluid discharge groove G2- 1), and a second working fluid discharge groove (G2-2) may be formed on the outer surface of the outer cylinder (45).

The second working fluid discharge groove G2-2 is formed in the first working fluid discharge groove G2 so as to enable excavation in the fixed state of the wing bit 20 when the outer tube 45 is twisted in the forward direction, -1 of the outer tube 45 so as to be aligned in series.

Accordingly, when excavating, a working fluid such as air or water is introduced into the working fluid inlet hole G1, and the excavated foreign matter flows into the first working fluid discharge groove G2-1 and the second working fluid discharge groove G2 -2). ≪ / RTI >

The wing bit 20 is rotated about the axis projection 21 and is folded in the direction of the bit body 10 so as to rotate about the shaft protrusion 21. As a result, It can easily escape to the outside through the inner surface of the cylinder.

Therefore, since the angle of the wing bit 20 can be firmly fixed only by the twist operation of the stopper member 30 and the outer tube 45, the wing bit 20 can be unfolded, It can be used to move the steel pipe, to perform other excavation work, or to perform additional work.

In addition, since the wing bit 20 and the shaft protrusion 21 are integrally formed as one unit, it is possible to prevent the collision between the components from the original, so that the wing bit 20 can be firmly supported even under the great external force and shock generated during the excavation process. 20 are inserted into the guide groove GD without being exposed to the outside of the bit body 10, the penetration of various foreign substances is blocked to prevent malfunction or malfunction, and the durability is remarkably improved Since the wing bit 20 can be easily repaired or replaced by removing the stopper member 30, the manageability of the apparatus can be greatly improved.

Figs. 11 and 12 are perspective views step-wise showing the wing bit 20 and the engagement bar 41 according to some embodiments of Fig.

More specifically, for example, as shown in Fig. 11, in the backward state of the engagement bar 41, the wing bit 20 is free from the engagement bar 41 and can be easily folded or unfolded, The wing bit 20 is inserted into the engaging rod 41 while the engaging rod 41 is partially inserted into the engaging groove 22 in the advancing state of the engaging rod 41, So that the angle can be maintained as it is.

Figs. 13 and 14 are perspective views step-wise showing the wing bit 20 and the engagement bar 41 according to some other embodiments.

13 and 14, the engaging groove 22 formed in the wing bit 20 can be changed into a slim shape, and accordingly, the leading end of the engaging rod 41 is also slim It can be changed into one form.

In addition, the shape of the engaging groove 22 of the wing bit 20 and the engaging rod 41 may vary widely.

Figs. 15 and 16 are perspective views stepwise showing the wing bit 20 and the rack gear 47 according to some further embodiments.

15 and 16, the wing bit fixing device 40 includes a rack gear 47 engaging with gear teeth ST formed on one side of the wing bit 20 in an unfolded state, And a rack gear forward / backward device capable of advancing and retracting the gear 47. Here, the rack gear forward / backward device may have the same structure and function as the engagement rod forward / backward device 42 described above.

Therefore, as shown in FIG. 16, when the rack gear 47 is advanced or retracted, the wing bit 20 can be unfolded or folded.

Therefore, the wing bit 20 can be always engaged with the rack gear 47 to precisely adjust the angle thereof, and the operator can easily perform the angle and fixing operation of the wing bit 20.

Figs. 17 and 18 are perspective views step-wise showing the wing bit 20 and the contact bar 48 according to some further embodiments.

17 and 18, the wing bit fixture 40 includes a contact bar 48 that can be selectively in contact with the plane P of the wing bit 20 in an unfolded state, And a contact bar forward / backward device capable of advancing and retracting the rod 48 in the plane (P) direction. Here, the contact bar forward / backward device may have the same structure and function as the above-described engagement bar forward / backward device 42 described above.

More specifically, for example, as shown in Fig. 17, in the backward state of the contact bar 48, the wing bit 20 is free from the contact bar 48 and can be easily folded or unfolded, 18, in the forward state of the contact rod 48, the tip of the contact rod 48 is brought into contact with the plane P, and the wing bit 20 is moved by the contact rod 48 They are bound and constrained and are not free, and the angle can be maintained.

19 is a part exploded perspective view showing a drill bit 100 (200) according to some embodiments of the present invention.

19, the excavation bit 100 (200) according to some embodiments of the present invention is characterized in that the bit body 10 is formed with the distal excavation surface 10a at its tip, The guide groove GD facing the direction of travel may be formed and the screw protrusion ST may be provided at the rear end so that the guide groove GD may be assembled with the inner tube 43 easily.

Therefore, as shown in FIG. 19, the bit body 10 can be assembled with the excavating bit 100 according to some embodiments of the present invention described above, and other existing excavating bits 200 can be assembled It is possible to use a variety of configurations such as replacing only the bit body 10 or using it as a multipurpose.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

10: bit body
10a: Advanced excavation surface
11: Wing bit accommodating groove
GD: Guide groove
20: Wing beat
20a: Wing bit excavation surface
21: Axial projection
30: Stopper member
40: Wing bit fixing device
41: Bite bar
42: Bite bar forward / backward device
SG: Sliding groove
43: My heart
43a: circumferential groove
44: cam projection
45: outer tube
46: cam home
46-1: Forward horizontal section
46-2: Moving slope section
46-3: Backward horizontal section
47: Racks
48: Contact bar
50:
G1: Working fluid injection hole
G2-1: First working fluid discharge groove
G2-2: Second working fluid discharge groove
ST: Gear teeth
P: plane
T: carbide tips
ST: Screw projection
100, 200: excavation bit

Claims (11)

A bit body having an advanced excavation surface formed on one side and a guide groove formed on the other side;
A wing bit which is formed on one side or both sides of the shaft body and which can be guided along the guide groove of the bit body and which can be assembled with the bit body about the axis projection guided along the guide groove and pivotable;
A stopper member provided on the bit body such that the shaft protrusion is not separated from the guide groove; And
A wing bit fixing device installed on the bit body and / or the stopper member, the wing bit fixing device fixing the wing bit so that the wing bit is rotated and fixed in a state in which the wing bit is pivoted on the basis of a traveling direction;
And an excavation bit. The method according to claim 1,
The wing bit fixing device includes:
A bite rod capable of selectively engaging a bite formed in one side of the wing bit in an unfolded state; And
A engaging bar forward / backward device capable of advancing and retracting said engaging bar in said engaging groove direction;
And an excavation bit. 3. The method of claim 2,
Wherein the engaging bar forward /
An inner tube provided on the bit body and having a sliding groove formed on an outer diameter surface to guide the engaging rod forward and backward;
A cam protrusion provided outside the engaging bar; And
And a cam groove formed on the inner circumferential surface so as to be inclined with respect to the advancing direction so as to guide the cam protrusion;
And an excavation bit. The method of claim 3,
The cam groove may include a forward horizontal section, a forward slope section, and a backward horizontal section so that the cam protrusion may move along the cam groove and the cam protrusion may be moved forward or backward when the outer cylinder is twisted in the forward direction with respect to the inner cylinder. Of the excavation bit. The method of claim 3,
Wherein the inner cylinder is integral with the bit body,
Wherein the stopper member is integrally formed with the outer cylinder,
A release preventing pin passing through the outer cylinder so as to be rotatable and rotatable about the outer cylinder and passing through a circumferential groove formed in the inner cylinder;
Further comprising an excavation bit. The method of claim 3,
Wherein the bit body and the inner cylinder have a working fluid injection hole formed in a central shaft portion thereof,
A first working fluid discharge groove is formed on an outer surface of the bit body, a second working fluid discharge groove is formed on an outer surface of the outer tube,
Wherein the second working fluid discharge groove is formed on an outer surface of the outer cylinder so as to be aligned in series with the first working fluid discharge groove at the time of forward twist rotation of the outer tube. The method according to claim 1,
The wing bit fixing device includes:
A rack gear engaged with gear teeth formed on one side of the wing bit in an unfolded state; And
A rack gear forward / backward device capable of advancing and retracting the rack gear;
And an excavation bit. The method according to claim 1,
The wing bit fixing device includes:
A contact bar capable of selectively contacting a plane of the wing bit in an unfolded state; And
A contact bar forward / backward device capable of advancing and retracting said contact rod in said planar direction;
And an excavation bit. The method according to claim 1,
The bit body has a wing bit accommodating groove of a shape corresponding to a part of the wing bit formed on one side thereof,
Wherein the guide groove is formed on an inner wall surface of the wing bit receiving groove in a direction opposite to the advancing direction. The method according to claim 1,
Wherein the wing bit is formed with axle protrusions on both sides thereof, and a wing bit excavation surface facing forward and / or laterally in a state in which the wing bit is rotated and unfolded is formed, and the wing bit excavation surface A bit for excavation where the tip is installed. The method of claim 3,
The bit body comprises:
Wherein the guide groove is formed at a front end thereof in a direction opposite to the traveling direction and a screw projection portion is provided at a rear end thereof so that the guide groove can be easily inserted and replaced, .

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