WO2014080920A1

WO2014080920A1 - Drilling tool

Info

Publication number: WO2014080920A1
Application number: PCT/JP2013/081209
Authority: WO
Inventors: 直小林; 央高遠
Original assignee: 株式会社タンガロイ
Priority date: 2012-11-20
Filing date: 2013-11-19
Publication date: 2014-05-30
Also published as: JPWO2014080920A1; JP6011637B2

Abstract

The present invention provides a drilling tool (1) including: an inner device (4) inserted within a casing pipe (2) in such a way as to be extendable and retractable along the centerline thereof; and a drill bit (5) attached to the distal end part of the casing pipe (2), the drill bit (5) being capable of engaging the inner device (4). The drill bit (5) has a first section (10) provided with at least one drilling member. The drill bit (5) has a wall surface (20c) against which the distal end part of the inner device (4) is capable of abutment in the centerline direction. The maximum outside diameter of a first section (19) of the drill bit (5) is greater than the outside diameter of the casing pipe (2).

Description

Drilling tools

The present invention relates to a drilling tool, and in particular, to a drilling tool used when reinforcing a weak ground.

In the field of tunnel excavation, the injection-type long tip receiving method (AGF method), which is a kind of earth retaining method for preventing the face from collapsing, is often used. In this construction method, a casing pipe that is, for example, a steel pipe is generally placed toward a fragile ground that is obliquely above and ahead of the face. And solidifying agents, such as mortar, are inject | poured in the casing pipe arrange | positioned in the predetermined position. Thereby, the solidifying agent is infiltrated into the surrounding weak ground through a hole or the like provided in the casing pipe. As a result, the fragile ground is strengthened and the tunnel can be excavated more safely and efficiently. An example of a tool for placing a casing pipe in the ground is a double-pipe excavation tool.

Patent Document 1 discloses an example of such a double-pipe excavation tool. In the excavation tool of Patent Document 1, an annular ring bit is fixed to the tip of a cylindrical casing pipe via a casing shoe. An inner bit is inserted into the casing pipe so as to advance and retract along the axis of the casing pipe. The inner bit is advanced through the casing pipe, the casing shoe and the ring bit until the tip portion having the bit portion involved in excavation protrudes from the center tip portion of the ring bit. A plurality of concave portions are formed on the outer peripheral surface of the inner bit at a predetermined distance from the tip thereof, and convex portions corresponding to the concave portions of the inner bit are formed on the inner peripheral surface of the ring bit. It is comprised so that engagement is possible. When the inner bit is rotated in the forward rotation direction with respect to the ring bit at a predetermined position, the concave portion of the inner bit and the convex portion of the ring bit are engaged with each other, and accordingly, the ring bit is also rotated in the forward rotation direction. To do. When the concave portion of the inner bit and the convex portion of the ring bit are engaged, the movement of the inner bit in the tool axis direction with respect to the ring bit is restricted. Furthermore, the inner bit has a stepped surface having a surface facing the tip side so that a force in the tip direction along the tool axis, that is, a striking force (or propulsive force) can be transmitted from the inner bit to the ring bit. Have This step of the inner bit abuts against the end wall facing the rear end of the ring bit when the recess of the inner bit and the projection of the ring bit are substantially or firmly engaged with each other. Can transmit striking force. Therefore, by applying a striking force to the inner bit while rotating the inner bit in the forward rotation direction, the inner bit and the ring bit can be excavated and advanced in the ground while rotating in the forward rotation direction. At this time, the inner bit is in charge of excavation on the inner peripheral side of the excavation surface of the natural ground, and the ring bit is in charge of excavation on the outer peripheral side. As a result, the casing pipe advances and is driven into the ground. After the casing pipe is driven into the ground, the inner bit is rotated in the reverse direction, released from engagement with the ring bit, and then withdrawn. Thereby, the solidifying agent is injected into the hollow casing pipe. However, the ring bit remains in the ground together with the casing pipe.

JP 2012-26132 A

During the excavation work for placing the casing pipe, in the excavation tool of Patent Document 1, the ring bit is rotated and pushed forward via the inner bit located inside the radial direction. At this time, in this excavation tool, in order to transmit both the rotational force and the striking force to the ring bit, the inner bit is rotated with respect to the ring bit and is engaged with the ring bit firmly to some extent. You need to be. However, in such operations, vibrations may occur due to, for example, a large load, which may loosen the engagement between the inner bit and the ring bit. As a result, there is a loss in the transmission of the striking force and rotational force from the inner bit to the ring bit, and the excavation force may be reduced. Due to such transmission loss, the excavation force is likely to be insufficient particularly in places where the strength of the ground is high.

Furthermore, in the excavation tool of Patent Document 1, the casing pipe must have a diameter large enough to insert the inner bit. Therefore, the outer diameter of the casing pipe is increased according to the outer diameter of the inner bit, and as a result, the outer diameter of the ring bit is also increased. The larger the outer diameter of the ring bit, the wider the excavation space that must be excavated, so the amount of solidifying agent input increases, resulting in an increase in cost. And there exists a relationship that excavation energy increases with the increase in this excavation space. Therefore, there is a demand for reducing the outer diameter or outer shape of the inner bit in order to perform excavation with higher efficiency.

Furthermore, in the tool of Patent Document 1, a bit for excavation is divided into a ring bit in charge of outer peripheral side excavation and an inner bit in charge of inner peripheral side excavation. For this reason, there is a possibility that at least one of the bits may be damaged when stones or earth and sand are caught in the gap between the two bits.

An object of the present invention is to provide an excavation tool that makes it possible to improve at least one of the above problems.

In particular, an object of the present invention is to provide an excavation tool capable of performing excavation with high efficiency.

According to one aspect of the invention,
An inner device that is inserted into a cylindrical casing pipe having a central axis extending from the distal end side to the proximal end side so as to advance and retreat along the axial line;
A drilling bit attached to the tip of the casing pipe, the drilling bit being engageable with the inner device,
The drill bit has a first part with at least one drill member and a second part proximal to the first part;
The excavation bit has a wall surface on which the tip of the inner device can abut in the axial direction,
A drilling tool is provided in which the maximum outer diameter of the first portion of the drill bit is greater than the outer diameter of the casing pipe.

According to the excavation tool according to one aspect of the present invention having the above-described configuration, the excavation bit having a wall surface on which the tip portion of the inner device can abut in the axial direction is positioned at the tip of the excavation tool, and the first of the excavation bit The maximum outer diameter of the part is larger than the outer diameter of the casing pipe. Therefore, the inner device inserted into the casing pipe can directly and firmly apply a striking force to the drill bit in the axial direction, and the casing pipe is led by the drill bit receiving the drilling force from the inner device. You can proceed firmly. Therefore, according to this excavation tool, it is possible to suppress transmission loss of force from the inner device to the excavation bit, and it is possible to excavate with high efficiency.

Preferably, the inner device includes a first engagement element, and the excavation bit includes a recess that opens in the second portion, and the recess includes a second engagement element that can be engaged with the first engagement element. When the inner device is inserted into the recess, the inner device has an engagement position where the first engagement element and the second engagement element engage with each other, and the first engagement element and the second engagement element. And can be moved relative to the excavation bit between release positions released from each other. The first engagement element of the inner device may be concave, and the second engagement element of the excavation bit may be convex. Alternatively, the first engagement element of the inner device may be convex and the second engagement element of the excavation bit may be concave.

More preferably, the first engagement element may be provided substantially parallel to the axis so as to extend to the tip surface of the inner device. The second engagement element may be provided substantially parallel to the axis in the recess of the excavation bit.

The tip surface that can hit the excavation bit in the inner device is preferably formed substantially perpendicular to the axis. In this case, the actual area B2 of the tip surface of the inner device is preferably in the range of 0.5 × B1 ≦ B2 ≦ 1.0 × B1 with respect to the area B1 of the circle circumscribing the tip surface.

Further, the excavation bit may be attached to the tip end portion of the casing pipe via a substantially cylindrical casing shoe. In this case, the inner device inserted into the casing pipe can reach the excavation bit through the inside of the casing shoe.

The length C2 in the axial direction of the portion of the inner device positioned directly inside the casing pipe is 0.3 × C1 ≦ C2 ≦ 0.8 × C1 with respect to the total length C1 in the axial direction of the inner device. It is good to be in the range.

The first portion of the drill bit may include one or more drill members. One or a plurality of excavation members may be provided continuously or intermittently from the intersection with the axis or the vicinity thereof to the outer peripheral surface.

Preferably, a plurality of excavation members are provided radially at substantially equal intervals around the central axis on the tip surface of the first portion of the excavation bit. And in the front end surface of the 1st part of a excavation bit, the intermediate area between adjacent excavation members is good to be formed so that it may recede gradually to the base end side of an excavation bit as it leaves from this excavation member. Further, in the excavation bit, a notch extending in the direction along the axis may be formed on the outer peripheral surface adjacent to the intermediate region. The excavating member may be a cemented carbide tip.

FIG. 1 shows a side view of an excavation tool according to an embodiment of the present invention. FIG. 2 shows a perspective view of the excavation tool of FIG. FIG. 3 shows a casing shoe in the excavating tool of FIG. 1, (a) is a perspective view, (b) is a side view, and (c) is a cross-sectional view. 4 shows an inner device in the excavation tool of FIG. 1, (a) is a perspective view, (b) is a side view, (c) is an end view on the tip side, and (d) is (c). FIG. 4 is a sectional view taken along line IV-IV. 5 shows the excavation bit in the excavation tool of FIG. 1, (a) is a side view, (b) is an end view on the distal end side, and (c) is a base end view taken in the direction of arrow P in (a). A side end view and (d) shows a perspective view. FIG. 6 is a schematic diagram for explaining the engagement and rotation between the inner device and the excavation bit in the excavation tool of FIG. 1. FIG. 7 shows a side view of an excavation tool according to another embodiment. FIG. 8 is a schematic diagram for explaining engagement and rotation between the inner device and the excavation bit in an excavation tool according to still another embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this specification, the term “tip” is used with respect to a portion or direction directed to the natural ground side when using the excavating tool, and the term “proximal end” is the side opposite to the natural ground when using the excavating tool. In other words, it is used in relation to the part or direction directed to the excavator side.

A drilling tool 1 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an appearance of a drilling tool 1 according to an embodiment of the present invention. FIG. 2 is a perspective view of the excavation tool 1.

As shown in FIGS. 1 and 2, an excavation tool 1 according to an embodiment of the present invention includes a casing shoe 3 that is fixed to the tip of a casing pipe 2 and an inner that is inserted into the casing pipe 2. A device 4 and a drill bit 5 attached to the casing shoe 3 so as to be engageable with the inner device 4 are provided. The excavation tool 1 has a central axis A extending from the distal end side to the proximal end side.

The casing pipe 2 is a cylindrical hollow member and has a central axis 2A extending from the distal end side to the proximal end side. The central axis A of the excavating tool 1 follows the central axis 2A of this casing pipe. The casing pipe 2 defines the introduction path of the solidifying agent when it is driven into a natural ground. The casing pipe 2 can be added sequentially as needed. In the case of the present embodiment, the material of the casing pipe 2 is carbon steel for mechanical structure (JIS G 4051), specifically, any one of S25C to S45C. A plurality of casing pipes 2, for example, 3 to 4 casing pipes 2 may be connected and used. However, the dimensions, material, number of connections, and the like of the casing pipe 2 can be changed as appropriate according to the application situation. Note that only one casing pipe 2 may be used. The casing pipe 2 is configured to be connected to each other by a screw mechanism. Therefore, a thread groove is formed in the connecting portion of each casing pipe 2. Here, the casing pipe has a female thread at the distal end and a male thread at the proximal end, but these may be reversed. In the excavation tool 1 of FIG. 1, only the casing pipe 2 located at the most distal end is shown, the excavation bit 5 is attached to the distal end portion 2b, and another casing is provided at the base end portion which is the other end (not shown). The pipe 2 is connected. The casing pipe 2 in the following description corresponds to a casing pipe located on the most distal end side.

The casing shoe 3 is a substantially cylindrical hollow member as shown in FIG. The casing shoe 3 is directly fixed to the tip of the casing pipe 2. In the case of the excavation tool 1 of the present embodiment, the casing shoe 3 is welded to the casing pipe 2, but may be fixed by other fixing methods or fixing means. For example, the casing shoe 3 may be directly attached to the tip of the casing pipe 2 using a screw mechanism. The casing shoe 3 has a role of connecting the casing pipe 2 and the excavation bit 5. The casing shoe 3 may be omitted in some cases. In this case, the excavation bit 5 may be directly connected to the casing pipe 2 like an excavation tool 100 according to another embodiment shown in FIG. it can. In the excavation tool 100 of FIG. 7, the excavation bit 5 may be connected to the casing pipe 2 by a method similar to the connection method of the casing shoe 3 and the excavation bit 5 described later. It is connected to the pipe 2. However, it is preferable to attach the casing shoe 3 because an existing pipe can be used and it can sufficiently cope with an impact force of a certain level or more. In this embodiment, the material of the casing shoe 3 is S45C, but the casing shoe 3 may be made of other materials.

The casing shoe 3 of the present embodiment has an axis 3A extending from the distal end side to the proximal end side. The axis 3A coincides with or substantially coincides with the central axis A of the excavation tool 1 when the excavation tool 1 is assembled as shown in FIG. The casing shoe 3 includes a first cylindrical portion (large-diameter cylindrical portion) 6 and a second cylindrical portion (small-diameter cylindrical portion) 7 having a smaller diameter than the first cylindrical portion in the direction of the axis 3A of the casing shoe 3. It has a shape connected via the part 8. The axes of the first cylindrical portions 6 coincide with the axis of the second cylindrical portion 7 and become the axis 3A. The second cylindrical portion 7 of the casing shoe 3 is positioned on the proximal end side of the first cylindrical portion 6 and is configured to be inserted inside the casing pipe 2. Thereby, the outer peripheral side surface of the second cylindrical portion 7 can substantially contact the inner peripheral surface of the front end portion 2 b of the casing pipe 2. The first cylindrical portion 6 of the casing shoe 3 is configured such that the excavation bit 5 is partially inserted inside thereof. Thereby, the inner peripheral surface of the first cylindrical portion 6 can substantially come into contact with the outer peripheral surface of the second base end portion of the excavation bit 5 described in detail later. Accordingly, the outer diameter of the second cylindrical portion 7 of the casing shoe 3 is substantially the same as the inner diameter of the casing pipe 2, and the inner diameter of the first cylindrical portion 6 is substantially the same as the outer diameter of the second base end portion of the excavation bit 5. is there. Further, the difference in the radial length between the outer peripheral surface of the second cylindrical portion 7 and the outer peripheral surface of the first cylindrical portion 6 (the radial length of the stepped portion 8) is almost equal to the thickness of the casing pipe 2 in the excavation tool 1. Are the same. Therefore, when the casing shoe 3 is partially inserted into the tip end portion of the casing pipe 2, the joint or connecting portion between the casing pipe 2 and the casing shoe 3 does not have a significant step (see FIGS. 1 and 2). .

Also, an inclined surface 6a is formed at the tip of the first cylindrical portion 6 of the casing shoe 3 so that the inner diameter gradually increases toward the tip. Due to the presence of the inclined surface 6a, the excavation bit 5 can be smoothly inserted into the casing shoe 3.

Furthermore, on the inner peripheral surface of the first cylindrical portion 6 of the casing shoe 3, an annular recess 6b is formed at an intermediate portion in the direction along the axis 3A (see FIG. 3C). A retaining ring 9 (see FIG. 2) used when fixing the excavation bit 5 is fitted into the annular recess 6b. The retaining ring 9 as the first fixing member has a substantially C shape and is generally attached manually. However, the retaining ring may be attached using a machine.

The inner device 4 is a rod-like member having an axis 4A extending from the distal end side to the proximal end side. In the assembled excavation tool 1, this axis 4A substantially coincides with, preferably coincides with, the central axis A of the excavation tool 1. As shown in FIG. 4, the inner device 4 is a rod-like member having a substantially circular cross section in a plane orthogonal to the axis 4A. The inner device 4 can be inserted into the casing pipe 2 so as to advance and retract along the axis 2A. The inner device 4 is configured to be able to transmit a rotational force and a striking force from an excavating machine (not shown) to the excavating bit 5. In the case of the present embodiment, the material of the inner device 4 is SNCM439 which is nickel chrome molybdenum steel defined in alloy steel for machine structure (JIS G 4053), but can be changed as appropriate.

The inner device 4 has a shape in which a first portion (small-diameter portion) 10 and a second portion (large-diameter portion) 11 having a larger diameter than the first portion are connected in the direction of the axis 4A. The axis of the first part 10 coincides with the axis of the second part 11 and becomes the axis 4A. The first portion 10 is located on the distal end side of the second portion 11 and is configured to be engageable with the excavation bit 5. The 2nd part 11 is comprised so that engagement with the rod 12 (refer FIG. 2) is possible. The rod 12 is a member that transmits force from the excavating machine (not shown) to the inner device 4. The outer diameter of the second portion 11 of the inner device 4 is substantially the same as the inner diameter of the casing pipe 2, and the outer diameter of the first portion 10 is substantially the same as the inner diameter of the second cylindrical portion 7 of the casing shoe 3. However, in the excavation tool 1 of FIG. 1, the inner device 4 is located inside the casing pipe 2 and the casing shoe 3 and also on the tip side along the axis A of the excavation tool 1 with respect to the casing pipe 2 and the casing shoe 3. It is also possible to move to the base end side, and it is possible to rotate around this axis A. Therefore, the outer diameter of the second portion 11 of the inner device 4 is smaller than the inner diameter of the casing pipe 2, and the outer diameter of the first portion 10 is smaller than the inner diameter of the second cylindrical portion 7 of the casing shoe 3. In the present embodiment, the intersection 10c between the distal end surface 10a and the outer peripheral surface 10b at the distal end portion of the first portion 10 of the inner device 4 is used to facilitate the insertion of the inner device 4 into the excavation bit 5. It is chamfered.

The inner device 4 has three recesses 13 arranged at equal intervals in the outer circumferential direction as shown in FIG. Each of these recesses 13 is formed over the entire length of the inner device 4 in parallel with the axis 4A. Therefore, the recess 13 opens on the distal end surface 10 a of the first portion 10 of the inner device 4 and also opens on the proximal end surface 11 a of the second portion 11. Moreover, the recessed part 13 is formed so that it may open to a radial direction outer side.

Further, the recess 13 has a first recess portion 14 that is wider than the other region on the proximal end side in a region of a constant distance in the axial direction on the distal end side of the inner device 4. At the time of excavation advancement in the excavation tool of FIGS. 1 and 2, the inner device 4 is rotated and used in the normal rotation direction (first rotation direction) K around the axis 4A. The first concave portion 14 includes an extended portion 14a provided on the opposite side of the forward rotation direction K around the axis 4A of the inner device 4, that is, so as to expand the concave portion 13 in the reverse rotation direction (second rotation direction). The positive rotation direction is a direction for causing the inner device 4 to engage with the excavation bit and rotating the inner device 4 together with the excavation bit 5 as will be apparent from the description to be described later. On the other hand, the reverse rotation direction is a direction for releasing the engagement between the inner device 4 and the excavation bit 5, for example.

The extended portion 14a is provided substantially parallel to the axis 4A so as to extend to the front end surface 10a of the inner device 4 in the same manner as the first concave portion 14. The first concave portion 14 of the convex portion 13 is provided as a concave first engaging element, in particular, the expanded portion 14a thereof. The extended portion 14a of the first concave portion 14 is shaped so as to engage with a convex portion (second engagement element) of the excavating bit 5 described later and to push the convex portion in the normal rotation direction K. Yes.

Further, the concave portion 13 includes a first concave portion 14 (wide portion) on the distal end side and a second concave portion (narrow portion on the proximal end side) having a narrower width (length in the circumferential direction) than the first concave portion. ) 15 and a different depth. Compared with the bottom surface of the second concave portion 15, the bottom surface of the first concave portion 14 is positioned on the axis 4 </ b> A side.

As shown in FIG. 4, the second portion 11 of the inner device 4 is positioned on the base end side of the first portion 10 described above, and the recess 13 extends to the base end surface 11 a of the second portion 11. ing. In the cross section of the recess 13 on the plane including the axis 4A, the distance from the bottom surface 13a of the recess 13 to the axis 4a of the inner device 4 excluding the first recess portion 14 is the portion in the first portion 10 and the second portion 11. There is no change in the part. Accordingly, since the second portion 11 has a larger outer diameter or outer shape than the first portion 10, the depth of the recess 13 is larger than the depth of the first portion 10 in the second portion 11. ing.

Further, the inner device 4 is formed with a through-hole 4b extending along the axis 4A so as to penetrate the distal end surface 10a and the proximal end surface 11a by the inner peripheral surface thereof. The through hole 4 b includes a first cylindrical space 16 and a second space 17.

In particular, a first cylindrical space 16 is partitioned and formed along the axis 4A by the inner peripheral surface of the inner device 4 inside the first portion 10. One end of the first cylindrical space 16 opens to the front end surface 10 a of the inner device 4, and the other end extends into the second portion 11. During the excavation, water is supplied to the first cylindrical space 16 from the excavating machine, and the water is discharged from the front end opening 16a positioned on the front end surface 10a of the inner device 4. This water is supplied from the excavating machine to the inner device 4 through a through hole (not shown) provided in the rod 12 disposed in the second space 17. Thereby, crushed grains such as stones generated by excavation can be discharged from the hole.

Further, as described above, the first cylindrical space 16 extends to the inside of the second portion 11 as well. The first cylindrical space 16 is continuous from the first portion 10 to the second portion 11. Continuing from the first cylindrical space 16, as shown in FIG. 4 (d), the cross-sectional area is further increased from the location away from the base end portion of the first portion 10 to the base end side. Large second space 17 is formed. That is, an internal space in which a part of the first cylindrical space 16 and the second space 17 having a larger cross-sectional area are continuous is formed inside the second portion 11. The axes of both the

spaces

16 and 17 coincide with the axis 4A of the inner device 4. The second space 17 is formed as a space for inserting the rod 12. A through hole 18 of a spring pin as a second fixing member for fixing the rod 12 to the second space 17 is formed in a portion on the proximal end side of the second portion 11 of the inner device 4. The rod 12 is configured not to rotate around the axis 4A in the second space 17 of the substantially square cross section of the inner device 4, and more specifically, the cross section thereof is substantially square here. However, the rod 12 may have a substantially circular cross section. In this case, the second space 17 may be formed to have a substantially circular cross section.

As will be described later, the tip surface 10 a of the inner device 4 can abut against the excavation bit 5 so as to exert an impact force on the excavation bit 5. Here, the tip surface 10a is formed substantially perpendicular to the axis 4A. The actual area B2 of the front end surface 10a of the first portion 10 of the inner device 4 with respect to the area B1 of the circumscribed circle circumscribing the front end surface 10a (that is, the circle having the diameter D1 shown in FIG. 4B). (That is, the area of the portion that can contact or contact the end wall surface 20c of the recess of the excavation bit 5 described later) is preferably in the range of 0.5 × B1 ≦ B2 ≦ 1.0 × B1. Note that the circumscribed circle of the front end surface 10a of the inner device 4 may be determined in the front end view of the inner device in FIG. Further, the axial direction of the second portion 11 of the inner device 4 positioned directly inside the casing pipe 2 as shown in FIG. 2 with respect to the total length (length in the axial direction) C1 of the inner device 4. Is preferably in the range of 0.3 × C1 ≦ C2 ≦ 0.8 × C1.

As shown in FIG. 5, the drill bit device (hereinafter referred to as a drill bit) 5 includes a first portion (hereinafter referred to as a first tip portion) 19 on the distal end side and a second portion (hereinafter referred to as a second portion) on the proximal end side. And an axis 5A extending so as to pass therethrough. The axis 5A substantially coincides with or coincides with the central axis A of the excavation tool 1 when the excavation tool 1 is assembled.

The excavation bit 5 has an opening 20a at the second base end 20 thereof, and is provided with a recess 20b that opens at the second base end at the opening 20a. The recess 20b is formed rotationally symmetrically along the axis 5A, and is generally defined by an inner peripheral surface of the substantially cylindrical side wall and an end wall surface 20c of the tip wall extending in a substantially radial direction. The end wall surface 20c of the recess 20b is configured such that the tip of the inner device 44 can abut in the axial direction.

The first tip 19 of the excavation bit 5 is configured as an excavation part of the excavation tool 1. The first tip 19 of the excavation bit 5 has a tip 19a. The distal end surface 19a is an outer surface on the distal end side of the distal end wall having the end wall surface 20c on the opposite side. The distal end surface 19 a extends in the radial direction from the intersecting portion 5 b with the axis 5 </ b> A of the excavation bit 5 toward the outer peripheral surface 5 c of the excavation bit 5. The distal end surface 19a of the first distal end portion 19 of the excavation bit 5 includes three excavation members (bit members) 21 that are directly involved in excavation of natural ground. The recess 20b of the excavation bit 5 is configured such that the inner device 4 described above can be inserted through the opening 20a. Here, the recess 20a extends to the first tip 19 (see FIG. 2). The second base end portion 20 is formed to have an outer diameter smaller than that of the first tip end portion 19.

The distal end surface 19a of the first distal end portion 19 of the excavation bit 5 has a substantially circular shape in FIG. When the excavation bit 5 is viewed from the side facing the distal end surface 19a of the first distal end portion 19 along the axis 5A, that is, in the distal end view of FIG. 5B, the outer peripheral surface 5c and the second proximal end portion of the excavation bit 5 20 is substantially invisible due to the presence of the tip surface 19a.

Further, when the excavation bit 5 is attached to the casing pipe 2, the second base end portion 20 is inserted into the casing shoe 3 and attached to the casing pipe 2 via the casing shoe 3. At this time, as clearly shown in FIGS. 1 and 2, the maximum outer diameter (the maximum length in the direction perpendicular to the axis A in FIG. 1) D <b> 2 of the first tip portion 19 is the outer diameter of the casing pipe 2 ( The length in a direction orthogonal to the axis A in FIG. Since the tip surface 19a of the excavation bit 5 extends from the intersection 5b with the axis to the outer peripheral surface 5c, the maximum outer diameter D2 of the first tip 19 is the rotation of the tip surface 19a of the first tip 19. This substantially corresponds to the diameter D4 of the locus. Therefore, the diameter D4 of the rotation locus of the tip surface 19a of the first tip part 19 is larger than the outer diameter D3 of the casing pipe 2. Here, the diameter D4 of the rotation locus of the distal end surface 19a of the first distal end portion 19 refers to the diameter of the circle when the distal end surface 19 is regarded as a circle in the distal end view of FIG. That is, the front end view (not shown) of the excavation tool 1 substantially corresponds to FIG. 5B. In the front end view of the excavation tool 1, the excavation bit 5 and the casing are disposed inside the front end surface 19a of the excavation bit 5. There is a shoe 3 and a casing pipe 2. Therefore, when the excavation tool 1 advances to the natural ground, the excavation bit 5, the casing shoe 3, and the casing pipe 2 are substantially hidden behind the distal end surface 19 a of the first distal end portion 19.

5B, in the end face view (tip view) of the first tip portion 19 of the excavation bit 5, the excavation member 21 has an outer peripheral end 19b (at least from the vicinity of the axis 5A on the tip surface 19a of the first tip portion 19). (Corresponding to 5c) is required to be covered in the radial direction, and in this embodiment, it is continuously provided from the vicinity of the central axis to the outer peripheral end. However, the excavation member 21 may be provided intermittently. One excavation member 21 may extend from the center of the front end surface 19a of the front end portion 19 (intersection with the axis) or from the vicinity thereof to the outer peripheral end. The range from the vicinity to the outer peripheral edge may be covered. As described above, the excavation member 21 is continuously or intermittently provided from the central axis 5A or the vicinity thereof to the outer peripheral end 19b, whereby the inner peripheral side excavation and the outer peripheral side excavation can be performed only by the excavation bit 5.

In the present embodiment, a drilling member region 22 in which the drilling member 21 can be mounted or formed is defined on the distal end surface 19a of the distal end portion 19 of the drilling bit 5. Although a cemented carbide tip is adopted as the excavation member 21, a tip made of another material may be used. The three excavation member regions 22 are provided in the circumferential direction in the radial direction around the axis 5A in the end surface view of the first tip portion 19 (at intervals of about 120 degrees), each of which is a belt-like shape having a certain width. It is an area. These three belt-like regions meet on the axis 5A. However, the number of excavation member regions 22 is not limited to this, and may be one or a plurality other than three. Further, all the three excavation member regions 22 extend on the same plane S1 orthogonal to the axis of the excavation bit 5. In the case of this embodiment, three excavation members 21 are arranged radially about the axis 5A. For this purpose, a recess (not shown) for inserting a plate-like carbide tip is formed in the belt-shaped excavation member region 22, and the carbide tip is fixed to the recess by brazing. However, the method of fixing the cemented carbide chip is not limited to this, and can be changed as appropriate.

Also, in the distal end surface 19a of the distal end portion of the excavation bit 5, there is an intermediate region 23 between one excavation member region 22 and another adjacent excavation member region 22. Since there are three excavation member regions 22, three intermediate regions 23 are formed around the axis 5A so as to be separated from each other. These intermediate regions 23 have the same configuration and the same shape. Each intermediate region 23 is formed so as to gradually recede toward the base end portion 20 as the distance from the excavation member region 22 increases (see FIG. 5A). This makes it easy for the excavated earth and sand to escape to the base end side, and also has an effect of reducing excavation resistance. One through hole 24 is formed near the center of each intermediate region 23, and this through hole 24 penetrates the tip surface 19a in the direction of the axis 5A. The through hole 24 extends substantially along a circular arc centered on the axis 5A, and has a substantially oval shape along the circular arc. The three through holes 24 are arranged at substantially equal intervals on a single circle centered on the axis 5A.

The shape of the through hole 24 can also be referred to as a bean shape. The “bean shape” here refers to a shape obtained by crushing an ellipse from one direction as shown in FIG. In the case of this embodiment, the bean shape is selected as the shape of the through-hole 24 from the ease of processing.

However, the shape of the through hole 24 is not limited to this, and may be another shape. Moreover, the through-hole 24 may be provided in another position, for example, may be provided in the intersection 5b with the axis 5A. In this case, the front end surface 19a of the excavation bit 5 extends from the vicinity of the intersection with the axis 5A toward the outer peripheral surface 5c, while the through-hole 24 is such that the inner device 4 does not protrude from the excavation bit 5 in the excavation tool 1. Can have a size of

The through hole 24 forms a passage that connects the outside and the inside (recess 20b) of the excavation bit 5. The through-hole 24 allows the water supplied via the inner device 4 to flow out to the outside, and can serve as an intake for excavated earth and sand.

Further, the outer periphery of the first tip 19 of the excavation bit 5 is formed so that the outer diameter does not change at the tip side portion, and subsequently, an inclined portion 19c in which the outer diameter gradually decreases is formed. Subsequent to the inclined portion 19c, a second base end portion 20 having a smaller diameter than the minimum diameter on the base end side of the inclined portion 19c is provided. The second base end portion 20 basically has a constant outer diameter in the direction of the axis 5A, but is provided with a recessed groove portion 25 having a smaller diameter near the base end. The recessed groove portion 25 is an annular groove for inserting the retaining ring 9 used when the excavation bit 5 is coupled to the casing shoe 3. Further, on the outer peripheral surface of the excavation bit 5 adjacent to the intermediate region 23 described above, a cutout portion 26 cut out in an arc shape in FIG. 5B is formed. The notch 26 extends on the outer peripheral surface of the excavation bit 5 to the middle of the inclined portion 19c in the direction along the axis 5A. This notch part has a role which makes the excavated earth and sand escape to the base end part 20 direction.

The recess 20b of the excavation bit 5 defines a substantially cylindrical space, as particularly shown in FIGS. 5 (c) and 5 (d). Then, three convex portions (second engagement elements) 27 are provided on the inner peripheral surface of the concave portion 20b of the excavation bit 5 at substantially equal intervals. The convex portion 27 is provided over substantially the entire length of the concave portion 20 b of the excavation bit 5. More specifically, the convex portion 27 is provided substantially parallel to the axis 5A so as to extend to the vicinity of the rear edge portion of the excavation bit 5 on the inner peripheral surface of the concave portion 20b. The convex portion 27 is dimensioned to engage with the extended portion 14 a of the first concave portion 14 when engaged with the first concave portion 14 of the inner device 4.

Furthermore, a first inner concave portion 28 and a second inner concave portion 29 are provided adjacent to the convex portion 27 on the inner peripheral surface that defines the concave portion 20 b of the excavation bit 5. The first inner recess 28 and the second inner recess 29 are formed so as to extend in parallel to the axis 5A. As shown in FIG. 5 (c), the first inner concave portion 28 is adjacent to the forward rotation direction K side of the related convex portion 27, and the second inner concave portion 29 is adjacent to the reverse rotational direction side of the related convex portion 27. Adjacent. The depth (diameter length) of the first inner recess 28 and the second inner recess 29 is substantially the same, but the width (circumferential length) of the first inner recess 28 is larger than the width of the second inner recess 29. wide. The first inner recess 28 is formed so as to be connected to the associated through hole 24, and partially forms a passage that communicates the inside and outside of the excavation bit 5. In the present embodiment, the material of the excavation bit 5 is SCM440, which is chromium molybdenum steel, as defined in alloy steel for machine structure (JIS G 4053), but is not limited thereto.

Next, the assembly of the above-described members and the operation of the assembled excavation tool 1 will be described.

In the excavation tool 1 of the present embodiment, the casing pipes 2 are connected to each other, and the casing shoe 3 is attached to the distal end portion 2b of the connected casing pipe 2 by welding. A drill bit 5 is attached to the casing shoe 3 using a retaining ring 9. The inner device 4 to which the rod 12 is connected is inserted into the internal space along the central axis A of the excavation tool 1 formed in this way. As a result, the tip of the inner device 4 passes through the inside of the casing shoe 3 via the casing pipe 2 and reaches the recess 20b of the excavation bit 5. The inner device 4 is inserted into the recess 20b of the excavation bit 5 such that the recess 13 in the first portion 10 thereof is aligned with the projection 27 of the recess 20b of the excavation bit 5. In this way, when the casing pipe 2, the casing shoe 3, the inner device 4, and the excavation bit 5 are assembled together, the axes of these members are generally aligned on the central axis A.

Note that the rod 12 is inserted into the second space 17 of the second portion 11 of the inner device 4. The rod 12 is firmly connected to the inner device 4 by a spring pin inserted into the through hole 18.

When the inner device 4 is inserted into the recess 20b of the excavation bit 5 and the inner device 4 is not engaged with the excavation bit 5 in the circumferential direction, the inner device 4 is rotated forward in the first direction with respect to the excavation bit 5. Rotate in direction K. Accordingly, the convex portion 27 that is the second engagement element of the excavation bit 5 enters the extended portion 14 a that is the first engagement element of the first concave portion 14 of the inner device 4, and the extended portion 14 a is engaged with the convex portion 27. Match. Thus, the inner device 4 is positioned at the engagement position where the extended portion 14 a and the convex portion 27 engage with each other with respect to the excavation bit 5.

On the contrary, when the inner device 4 is positioned at the engagement position with respect to the excavation bit 5, the inner device 4 is rotated in the reverse rotation direction, which is the second direction, with respect to the excavation bit 5. The convex portion 27 is separated from or disengaged from the extended portion 14 a of the inner device 4. Thus, the inner device 4 is positioned in the release position where the extended portion 14a and the convex portion 27 are released from each other with respect to the excavation bit 5. In this way, the inner device 4 can move relative to the excavation bit 5 between the engagement position and the release position.

By rotating the inner device 4 in the normal rotation direction K with respect to the excavation bit 5, the inner device 4 is moved to the excavation bit 5 in the circumferential direction as schematically shown in FIG. Engage. At this time, when the inner device 4 further rotates in the forward rotation direction K, the side surface 14b of the concave portion 13 of the inner device 4 facing the positive rotation direction K side of the first concave portion 14 becomes convex on the inner periphery of the excavation bit 5. The side surface 27a of the portion 27 facing in the reverse rotation direction is brought into strong contact with the side surface 27a, and the side surface 27a of the convex portion 27 is pushed in the forward rotation direction K. As a result, the excavation bit 5 can rotate in the normal rotation direction K with the movement of the inner device 4. Thus, the rotational force of the inner device 4 is properly and securely transmitted to the excavation bit 5. At this time, since the excavation bit 5 is connected to the casing shoe 3 via the retaining ring 9, the excavation bit 5 can rotate with respect to the casing shoe 3.

Further, in the assembled excavation tool 1, the casing pipe 2 is hidden in the shadow of the distal end surface 19a of the distal end portion 19 of the excavation bit 5 in the distal end view. In such a state, the distal end surface 10a of the first portion 10 of the inner device 4 is abutted in the axial direction against the end wall surface 20c on the distal end side inside the recess 20b of the excavation bit 5. During the excavation work, the inner device 4 hits the end wall surface 20c. As a result, the striking force is reliably transmitted to the excavation bit 5 through the inner device 4.

In this excavation tool 1, during the excavation work, the inner device 4 is pushed forward with respect to the excavation bit 5 while being rotated with respect to the excavation bit 5 with the tip portion of the excavation bit 5 facing the natural ground. Thereby, a rotational force can be transmitted to the excavation bit 5 and a striking force can be exerted on the excavation bit 5, whereby the casing pipe 2 can be delivered to a predetermined depth. After placing the casing pipe 2, the inner device 4 is rotated in the reverse rotation direction and pulled out, and the excavation bit 5 is left in the ground together with the casing pipe 2. Thereafter, the solidifying agent is supplied to the hollow internal space of the casing pipe 2.

Furthermore, the operation and effect of the excavation tool 1 of this embodiment will be described.

In the excavation tool 1 of the present embodiment, as described above, the excavation bit 5 has a wall surface on which the tip of the inner device can abut in the axial direction. The maximum outer diameter is larger than the outer diameter of the casing pipe 2, and the excavation member 21 is provided so as to cover from the vicinity of the central axis of the distal end surface of the excavation bit 5 to the outer peripheral surface. Thus, only the excavation bit 5 is provided with a configuration as an excavation part, that is, an excavation member 21, and excavation in the ground can be performed by transmitting force to the excavation bit 5. That is, the excavation tool of Patent Document 1 employs a configuration in which a bit involved in underground excavation is divided into a ring bit for excavation on the outer peripheral side and an inner bit for excavation on the inner peripheral side. In the excavation tool 1 of the form, the entire excavation area is covered by the excavation bit 5 integrally provided with the outer peripheral side excavation bit and the inner peripheral side excavation bit. Since the excavation bit is configured in this way, when the inner device 4 is pushed forward with respect to the excavation bit 5, the striking force, which is the axial force, is reliably transmitted from the inner device 4 to the excavation bit 5. The On the other hand, when the first engagement element of the inner device 4 is engaged with the second engagement element of the excavation bit 5, the rotational force, which is a radial force, is transmitted from the inner device 4 to the excavation bit. Thus, the transmission mechanism of the rotational force from the inner device 4 to the excavation bit 5 and the transmission mechanism of the striking force from the inner device 4 to the excavation bit 5 are in an independent relationship in the excavation tool 1. Therefore, in the excavation tool 1, at least one of the rotational force and the striking force from the excavating machine, in particular the striking force, can be securely transmitted from the inner device 4 to the excavation bit 5. Therefore, it is possible to reduce the transmission loss of force when the rotational force and the striking force applied to the inner bit are transmitted to the ring bit. Therefore, according to the excavation tool 1 of the present embodiment, it is possible to mitigate or prevent such a decrease in excavation efficiency due to transmission loss, and to perform highly efficient excavation. Furthermore, since the excavation resistance becomes very large at a location where the strength of the ground is high, such a configuration of the present embodiment is particularly effective.

In addition, since the excavation bits in the excavation tool 1 of the present embodiment have the above-described configuration, stones and earth and sand are bitten between the ring bit and the inner bit in the conventional excavation tool, and the bits are damaged. It has nothing to do with the problem. This leads to a longer life of the bit and greatly reduces the cost of the entire tool.

Furthermore, in the present embodiment, the inner device 4 has a first engagement element extending to the tip surface at the tip, and the excavation bit 5 has a second engagement element in the recess. The inner device 4 can be engaged with the excavation bit 5 in the circumferential direction by the engagement of the first and second engagement elements. Thus, in the excavation tool 1, since the first engagement element of the inner device 4 is provided so as to extend to the tip end surface, the radial dimension of the inner device 4 can be relatively easily reduced.

On the other hand, in the excavation tool of Patent Document 1, the tip portion of the inner bit must protrude from the center portion of the ring bit toward the tip side. Therefore, the inner bit must be provided with an engagement element on its outer peripheral surface that is some distance away from its tip. Therefore, in the excavation tool of patent document 1, there are many restrictions regarding reducing the outer diameter of the inner bit.

Therefore, compared with the inner bit of the excavating tool of Patent Document 1, the inner device 4 in the excavating tool of this embodiment has an advantage in reducing the radial dimension (width in the direction perpendicular to the axis). Therefore, in this embodiment, only the relatively small-diameter inner device 4 is pulled out, and the excavation bit 5 is left in the ground together with the casing pipe 2. Therefore, according to the excavation tool 1, it is possible to make the casing pipe 2 small in diameter so that the relatively small diameter inner device 4 can pass therethrough. Therefore, according to the excavation tool 1, the energy required for excavation can be reduced. As a result, the amount of the solidifying agent to be introduced into the casing pipe 2 can be greatly reduced as compared with the conventional case. As a result, the cost of the entire construction can be suppressed.

Further, in the present embodiment, the excavation bit 5 and the inner device 4 have a very simple combination of the convex portion 27 in the concave portion of the excavation bit 5 and the concave portion 13 of the first portion 10 on the tip side of the inner device 4. They are connected in the circumferential direction by the engagement relationship. In this engagement relationship, the inner device 4 can be easily pulled out of the casing pipe 2 simply by rotating the inner device 4 in the reverse rotation direction and pulling the inner device 4 backward from the casing pipe 2.

On the other hand, in the excavation tool of Patent Document 1, since the distal end portion of the inner bit has to protrude from the central portion of the ring bit toward the distal end side, the engagement structure between the inner bit and the excavation bit is complicated, and those Is connected to the tip of the drilling tool. Therefore, it is easy for stones and earth and sand to enter the connection between the inner bit and the ring bit. When stones are caught in the gap between the ring bit and the inner bit, the ring bit and inner bit are affected by the effect. Since it is difficult to release the engagement, the excavation tool of Patent Document 1 requires further contrivance for releasing the engagement.

On the other hand, since the excavation tool 1 of the present embodiment uses the single excavation bit 5 having the above-described configuration, the engagement structure between the inner device and the excavation bit is simplified, and the engagement portions thereof are used. It is also possible to reduce the possibility of problems.

Further, as described above, the actual area B2 of the tip surface 10a of the first portion 10 of the inner device 4 is 0.5 × B1 with respect to the area B1 of the circumscribed circle of the tip surface of the first portion 10 of the inner device 4. ≦ B2 ≦ 1.0 × B1 is preferable. Since the actual area B2 of the front end surface of the inner device 4 on the first portion 10 side is within this range, the striking force applied to the inner device 4 by the rod 12 can be most efficiently transmitted to the excavation bit 5. It becomes possible. In the case of B2 <0.5 × B1, the striking surface becomes too small and the strength of the inner device 4 may be lowered, which is not preferable. In addition, it is practically impossible when B2> B1.

Further, as described above, the length C2 in the axial direction of the second portion 11 of the inner device 4 is 0.3 × C1 ≦ C2 ≦ 0.8 × C1 with respect to the entire length C1 of the inner device 4. It is preferable to be in the range. By setting the length C2 of the large-diameter portion 11 of the inner device 4 within this range, the life and excavation performance of each member can be maintained at appropriate levels. In the case of C2 <0.3 × C1, the protruding amount of the first portion 10 of the inner device 4 from the casing pipe 2 becomes too large, so that the length of the casing shoe 3 is excessively increased to cover it. There is a need to reinforce. As a result, the contact area between the casing shoe 3 and the inner device 4 or the excavation bit 5 is increased, and the mutual wear progresses quickly, which may cause problems such as rattling. In the case of C2> 0.8 × C1, since the protruding amount of the first portion 10 of the inner device 4 from the casing pipe 2 becomes too small, it may be necessary to excessively reduce the length of the casing shoe 3 accordingly. . As a result, the fixing force of the excavation bit 5 by the casing shoe 3 is reduced, and problems such as rattling are likely to occur.

Although the present invention has been described based on the above two embodiments, the present invention allows various modifications. For example, as schematically shown in FIG. 8, the first engagement element of the inner device 4 may be a convex part 50, and the second engagement element of the excavation bit 5 may be a concave part 52. Moreover, in the said embodiment, although the number of the 1st engagement elements of the inner device 4 was made into multiple, and the number of the 2nd engagement elements of the excavation bit 5 was made into multiple, each may be one. However, in order to more suitably transmit the force from the excavating machine to the excavating bit, the number of the first engaging elements of the inner device 4 is equal to the number of the second engaging elements of the excavating bit 5, and each of them is plural. Yes, they may be arranged rotationally symmetrical around the central axis A of the excavation tool.

The exemplary embodiments of the present invention and the modifications thereof have been described above. However, the present invention can be variously modified and changed without departing from the spirit and scope of the present invention defined by the claims of the present application. Replacement and change are possible.

Claims

An inner device (4) inserted into a cylindrical casing pipe (2) having a central axis extending from the distal end side to the proximal end side so as to be movable back and forth along the axis;
A drill bit (5) attached to the tip of the casing pipe (2), the drill bit (5) being engageable with the inner device (4);
The drill bit (5) has a first part (19) with at least one drill member (21) and a second part (20) proximal to the first part,
The excavation bit (5) has a wall surface (20c) capable of abutting the tip of the inner device (4) in the axial direction,
The excavation tool (1, 100), wherein the maximum outer diameter of the first part (19) of the excavation bit (5) is larger than the outer diameter of the casing pipe (2).
The inner device (4) comprises a first engagement element;
The excavation bit (5) includes a recess (20b) that opens at the second portion (20), and the recess includes a second engagement element engageable with the first engagement element,
When the inner device (4) is inserted into the recess, the inner device (4) has an engagement position where the first engagement element and the second engagement element engage with each other; The first engagement element and the second engagement element can move relative to the drill bit between a release position released from each other;
The excavation tool according to claim 1.
The first engagement element (14a) of the inner device (4) is concave,
The second engagement element (27) of the drill bit (5) is convex;
Drilling tool (1) according to claim 2.
The first engagement element (50) of the inner device (4) is convex;
The second engagement element (52) of the drill bit (5) is concave;
Drilling tool (1) according to claim 2.
The first engagement element is provided substantially parallel to the axis so as to extend to the tip surface (10a) of the inner device (4),
The second engagement element is provided substantially parallel to the axis in the recess of the excavation bit (5).
Drilling tool (1) according to claim 3 or 4.
The front end surface of the inner device (4) that can hit the excavation bit (5) is formed substantially perpendicular to the axis,
The actual area B2 of the tip surface of the inner device (4) is 0.5 × B1 ≦ B2 ≦ 1.0 × B1 with respect to the area B1 of the circle circumscribing the tip surface of the inner device (4). Excavation tool (1) according to any one of claims 1 to 5, in the range of
The excavation tool (1) according to any one of claims 1 to 6, wherein the excavation bit is attached to the tip of the casing pipe (2) via a substantially cylindrical casing shoe (3). .
The length C2 in the axial direction of the portion (11) of the inner device (4) positioned directly inside the casing pipe with respect to the total length C1 in the axial direction of the inner device (4) is The excavation tool (1) according to any one of claims 1 to 7, wherein the excavation tool (1) is in a range of 0.3 x C1 ≤ C2 ≤ 0.8 x C1.
The first portion of the drill bit (5) comprises one or more drill members (21);
The excavation tool according to any one of claims 1 to 8, wherein the one or more excavation members are provided continuously or intermittently from an intersection with or near the axis to the outer peripheral surface. 1).
The plurality of excavation members (21) are provided radially at substantially equal intervals around the axis on the tip surface (19a) of the first portion (19) of the excavation bit (5). The excavation tool (1) according to any one of 1 to 9.
In the tip surface of the first portion (19) of the excavation bit (5), an intermediate region (23) between adjacent excavation members (21) is excavated as the distance from the excavation member (21) increases. The excavation tool (1) according to claim 10, wherein the excavation tool (1) is formed so as to gradually retreat toward the base end side of the bit.
The excavation bit according to claim 11, wherein a notch (26) extending in a direction along the axis is formed on an outer peripheral surface adjacent to the intermediate region (23) in the excavation bit (5). Tool (1).
The excavation tool (1) according to any one of claims 1 to 12, wherein the excavation member (21) is a cemented carbide tip.