JP3036345B2 - Drilling tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drilling tool used for various anchoring works or various well drilling works, and more particularly to a drilling tool which can be freely expanded during excavation.

[0002]

2. Description of the Related Art As an excavation method used for various anchor works, there is a method of excavating while reinforcing the inner peripheral surface of an excavation hole formed by an excavation tool with a pipe for preventing collapse of a hole wall. Among the above-mentioned construction methods, in particular, when excavation by rotary impact excavation is performed, for example, as shown in FIGS.
A drilling tool whose lower end is freely expandable may be used. Here, FIG. 6 and FIG. 7 are front views of the reduced diameter state and the expanded diameter state, respectively, and FIG. 8 is a partial side sectional view of the excavating tool in the expanded state.

[0003] In these figures, reference numeral 1 denotes a device which receives the impact force of a hammer (not shown) and the rotational force of a hammer cylinder (not shown) driven by compressed air. It has a cylindrical shape, and has two shaft holes 1A and 1B in its lower end face symmetrically with respect to the axis of the device 1.
Are formed.

Each of the shaft holes 1A and 1B has a block shaft 2
A, 2B are rotatably and non-removably fitted around the shaft from below, and are fitted to the lower ends of the respective block shafts 2A, 2B.
Blocks 4A and 4B each having a semicircular shape having substantially the same diameter as the device 1 and having a large number of chips 3 implanted on the lower end surface thereof are
It is provided in a state where the opposing straight end faces 5A and 5B are in contact with each other. Here, these straight end faces 5
Each of A and 5B is a plane parallel to the axis of the device 1 and extending along the radial direction of the device 1.

[0005] When the device 1 is rotated in the excavation rotation direction (the direction of the arrow X in FIG. 6), the block shafts 2A and 2B have the straight end faces 5A and 5B of both blocks 4A and 4B at one end. The blocks 4A and 4B are eccentric from the axis of the device 1 so as to abut and protrude from the outer peripheral surface of the device 1 by a predetermined excavation amount.

Further, the excavating tool is slidably inserted into a casing pipe 6 having substantially the same diameter. A reduced-diameter tube 7 that fits with the enlarged-diameter portion 1C formed on the outer peripheral surface of the device 1 is integrally fixed to the inner periphery of the lower end portion of the casing pipe 6 by a method such as welding.

The blocks 4A and 4B are connected to the casing pipe 6
When the device 1 is rotated in the excavation rotation direction, the blocks 4A and 4B rotate around the block shafts 2A and 2B due to the excavation resistance from the state shown in FIG. Then, the blocks 4A, 4B become straight end faces 5A, 5A.
B with the one end portions thereof in contact with each other.
B along the longitudinal direction of FIG.
As shown in (1), the other ends of the blocks 4A and 4B protrude from the outer peripheral surface of the device 1 by a predetermined amount. Block 4
The rotation of A and 4B stops when the further displacement of the straight end faces 5A and 5B becomes impossible.

Then, in the state shown in FIGS. 7 and 8,
When the hammer and the hammer cylinder are operated while the tips of the blocks 4A and 4B are pressed against the ground, their rotational force and impact force are transmitted via the device 1 to the blocks 4A and 4B.
4B, the blocks 4A and 4B move up and down and rotate in the excavation rotation direction. As a result, local collapse and shear failure of the ground by the chip 3 occur, and excavation is performed.

On the other hand, the impact force of the hammer is transmitted to the casing pipe 6 at the same time as excavation due to the contact between the enlarged diameter portion 1C and the reduced diameter pipe 7 accompanying the vertical movement. The tip of the reduced-diameter pipe 7 bites into the ground, and the casing pipe 6 is pushed into the ground.

[0010] The excavated earth and sand is compressed air discharged when a hammer piston (not shown) falls in the hammer cylinder through air holes 8A and 8B provided on the bottom surface of the device 1. As a result, the excavation tool moves from the lower end side into the casing pipe 6 via a discharge groove (not shown) provided on the side surface of the device 1 and is discharged further upward therefrom.

When the excavation is completed, the hammer cylinder is rotated in a direction opposite to the excavation rotation direction. Then
Due to the excavation resistance, the blocks 4A and 4B rotate to the position shown in FIG. 6 and reduce in diameter, so that the excavating tool can slide in the casing pipe 6. First, only the excavating tool is pulled up from the excavation hole. Next, after inserting a reinforcing rod or the like into the casing pipe 6 as necessary, the casing pipe 6 is filled with cement or the like while being pulled up from the drilling hole, thereby completing the anchoring work.

[0012]

By the way, in rotary impact excavation, an impact force along the axis of the excavation tool and a rotational force along the excavation rotation direction act on the excavation tool. However, in the case of the above-described conventional excavating tool, the impact force and the rotational force are directly transmitted from the blocks 4A and 4B to the lower end surface of the device 1, and are also transmitted to the shaft holes 1A and 1B via the block shafts 2A and 2B. Directly communicated.

As a result, in the above-mentioned conventional excavating tool, the lower end surface of the device 1 may be locally worn by the impact force and the rotating force, and the blocks 4A and 4B during excavation may become unstable. Further, the impact force and the rotational force transmitted to the shaft holes 1A and 1B via the block shafts 2A and 2B,
In some cases, the upper ends of the block shafts 2A and 2B collide with the bottom surfaces of the shaft holes 1A and 1B to apply an eccentric load to the upper ends of the block shafts 2A and 2B, and the upper ends of the block shafts 2A and 2B may be deformed or damaged. This was one of the causes of instability of the blocks 4A and 4B during excavation.

If the blocks 4A and 4B become unstable during excavation, the block shafts 2A and 2B and the block 4
An unbalanced load is applied to the joints with A and 4B, and the resulting stress concentration causes a so-called "neck break" phenomenon, in which the joints are bent or bent.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a device, which is vertically erected and receives a rotational force about an axis thereof, has a lower end surface substantially the same as the diameter of the device. A pair of blocks each having a semicircular diameter and having a number of blades provided on a lower end surface thereof, and a block shaft for supporting the blocks and attached to a lower end surface of the device are provided. With the excavation rotation of the device, the opposing straight end faces of the block abut against each other at one end, and the other end of the block protrudes by a predetermined width from the outer peripheral surface of the device. In the drilling tool decentered from the axis, in particular, a surface having a horizontal component, on the straight end face of each block, is respectively extended along the longitudinal direction of the straight end face, and the straight end face, Through a surface having a these horizontal component it is to its characterized by being contactable with each other.

[0016]

In the excavating tool according to the present invention, since a surface having a horizontal component extends on the straight end face of each block along the longitudinal direction of the straight end face, the block on the straight end face is provided. The contact area between them increases by the extension of the plane having the horizontal component. Therefore, the impact force and the rotational force received by the blocks during excavation are dispersed by an increase in the contact area between the blocks due to the extension of the surface having the horizontal component.

[0017]

Embodiments of the present invention will be described below in more detail with reference to the drawings. In addition, since the present invention has the main feature of the structure of the block in the excavating tool shown in FIGS. 6 to 8 in particular, other portions of the excavating tool are not described in FIGS. The same reference numerals as in Fig. 8 denote the same parts, and a description thereof will be omitted.

FIGS. 1 and 3 show an example of a drilling tool 10 according to the present invention. FIG. 1 is a partial sectional side view of the drilling tool 10 in an expanded state, and FIGS. It is a front view of a state and a diameter expansion state. Block holes 2A, 2B are provided in shaft holes 1A, 1B formed in the lower end surface of the device 1.
B is inserted, and blocks 4A and 4B are respectively provided at the lower ends of the block shafts 2A and 2B with straight end faces 11A and 4B.
A and 11B are provided in a state where they are in contact with each other.

Here, these straight end faces 11A, 11B
Are planes extending in parallel with the axis of the device 1 and along the radial direction of the device 1.
On the straight end face 11A of the block indicated by A, a convex portion 12A protruding toward the straight end face 11B of the opposing block 4B.
Are extended along the longitudinal direction of the straight end faces 11A and 11B. On the other hand, the straight end face 1 of the block denoted by reference numeral 4B
1B includes a concave portion 12B that engages with the convex portion 12A.
Like 2A, it extends along the longitudinal direction of straight end faces 11A and 11B.

As a result, the convex portion 12A and the concave portion 1
With the formation of 2B, horizontal surfaces are respectively formed on the upper and lower surfaces of the convex portion 12A and the concave portion 12B along the longitudinal direction of the straight end surfaces 11A and 11B.

Next, excavation using the excavating tool 10 having the above configuration will be described below. First, from the lower end of the reduced diameter pipe 7 fixed to the casing pipe, the blocks 4A, 4
B is projected, and the device 1 is rotated in the excavation rotation direction (the arrow X direction in FIG. 2). Then, blocks 4A and 4B
However, from the state shown in FIG.
Straight end faces 11A, 11B while rotating around A, 2B
Are displaced along the longitudinal direction of the straight end faces 11A,
At the time when the end portions 11B abut each other at one end thereof, further displacement of the blocks 4A and 4B becomes impossible, and
The rotation of A and 4B stops. On the other hand, blocks 4A and 4B
Are protruded by a predetermined amount from the outer peripheral surface of the device 1 as the blocks 4A and 4B rotate. This state is shown in FIG.

Then, in the state shown in FIG.
By operating the hammer and the hammer cylinder (both not shown) provided on the upper end side of the device 1 while pressing the lower ends of A and 4B against the ground, their rotational force and impact force are transmitted through the device 1. Blocks 4A, 4B
And the blocks 4A and 4B move up and down and rotate in the excavation rotation direction to perform excavation.

When the excavation is completed, the hammer cylinder is rotated in a direction opposite to the excavation rotation direction. Then
Due to the excavation resistance, the blocks 4A and 4B rotate to the position shown in FIG. 2 and reduce the diameter, so that the excavation tool 10 can slide in the casing pipe 6. Therefore, the drilling tool 10
Only the hole is lifted from the borehole, and the process proceeds to the subsequent steps.

By the way, in the excavating tool 10 of this embodiment, the straight end faces 11A, 11B of the blocks 4A, 4B.
In addition, a convex portion 12A and a concave portion 12B that engage with each other are extended along the longitudinal direction of the straight end surfaces 11A and 11B, and accordingly, the upper and lower surfaces of the convex portion 12A and the concave portion 12B have straight end surfaces 11A. , 11B are each formed with a horizontal plane along the longitudinal direction.

That is, the convex portion 12A and the concave portion 12B
Are in contact with each other via these horizontal planes,
The contact area between the blocks 4A and 4B on the straight end faces 11A and 11B increases by the extension of the horizontal plane. Accordingly, the impact force and the rotational force applied to the blocks 4A and 4B during excavation are the same as the blocks 4A and 4B associated with the extension of the horizontal plane.
As a result, the stress concentration on the lower end surface of the device 1 and the upper ends of the block shafts 2A and 2B is prevented.

Therefore, wear of the lower end surface of the device 1 due to the stress concentration is prevented, and deformation or breakage of the upper ends of the block shafts 2A, 2B causes the excavating blocks 4A,
4B does not become unstable. Therefore, an unbalanced load is less likely to be applied to the joint between the block shafts 2A, 2B and the blocks 4A, 4B, and as a result, "neck break" due to stress concentration on the joint is prevented.

For example, as shown in FIG. 4, a horizontal plane 13 extends between the straight end faces 11A and 11B along the longitudinal direction of the straight end faces 11A and 11B, and the straight end faces 11A and 11B are extended.
B may be brought into contact with each other via the horizontal plane 13. In this case, the contact area between the blocks 4A and 4B on the straight end faces 11A and 11B is increased by the extension of the horizontal plane 13, so that the impact force in the axial direction of the excavating tool 10 received by the blocks 4A and 4B during excavation is reduced. Thirteen extensions are distributed. Therefore, stress concentration on the lower end surface of the device 1 and the upper ends of the block shafts 2A and 2B is prevented, and as a result, the same effect as in the above embodiment can be obtained.

As shown in FIG. 5, for example, an inclined surface 14 having a horizontal component extends between the straight end surfaces 11A and 11B along the longitudinal direction of the straight end surfaces 11A and 11B. , 11B may be brought into contact with each other via the inclined surface 14. Also in this case, the straight end faces 11A, 11A
Since the contact area between the blocks 4A and 4B in B increases by the extension of the inclined surface 14, the same effect as in the above-described embodiments can be obtained.

Further, if necessary, at least one of the horizontal planes formed on the upper and lower surfaces of the convex portion 12A and the concave portion 12B shown in FIGS.
Of course, it is also possible to set it to 4.

[0030]

As described above, in the excavating tool of the present invention, even if an impact force or a rotational force acts on the block during excavation, an uneven load is less likely to be applied to the joint between the block shaft and the block. I have. Therefore, occurrence of “neck break” due to stress concentration at these joints is prevented.

[Brief description of the drawings]

FIG. 1 is a partial side sectional view showing an example of a structure of a drilling tool used as a first embodiment of the present invention in an expanded state.

FIG. 2 is a front view of a reduced diameter state showing an example of a structure of a drilling tool used as a first embodiment of the present invention.

FIG. 3 is a front view of an expanded state showing an example of a structure of a drilling tool used as a first embodiment of the present invention.

FIG. 4 is a partial cross-sectional view showing an example of a structure of an excavating tool used as a second embodiment of the present invention in an expanded state.

FIG. 5 is a partial side sectional view showing an example of a structure of a drilling tool used as a third embodiment of the present invention in an expanded state.

FIG. 6 is a front view of an example of the structure of a conventional excavation tool in a reduced diameter state.

FIG. 7 is a front view showing an example of the structure of a conventional excavating tool in an expanded state.

FIG. 8 is a partial side sectional view showing an example of the structure of a conventional excavating tool in an expanded state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Device 1A, 1B Shaft hole 1C Enlarged diameter part 2A, 2B Block shaft 3 Chip 4A, 4B Block 5A, 5B, 11A, 11B Straight end face 6 Casing pipe 7 Reduced diameter pipe 8A, 8B Air hole 10 Drilling tool 12A Convex part 12B recess 13 horizontal plane 14 inclined plane X block excavation rotation direction

────────────────────────────────────────────────── ─── Continuing on the front page (72) Takeshi Hayashi 1528 Nakashinda, Yokoi, Kobe-cho, Anpachi-gun, Gifu Prefecture Mitsubishi Materials Corporation Gifu Works (56) References JP-A-4-265391 (JP, A) JP-A-6-26289 (JP, A) JP-A-4-169969 (JP, A) JP-A-4-169691 (JP, A) JP-A-4-213690 (JP, A) JP-A-3 -250192 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) E21B 4/06 E21B 10/32

Claims (4)

(57) [Claims] 1. A device, which is vertically erected and receives a rotational force about its axis, has a semicircular shape having a diameter substantially equal to the diameter of the device on a lower end surface thereof, and a number of blades provided on the lower end surface. Provided a pair of blocks, and a block shaft that is mounted on the lower end surface of the device to support this block,
The position of the block shaft is adjusted such that, with the excavation rotation of the device, opposing straight end surfaces of the block abut against each other at one end, and the other end of the block projects a predetermined width from the outer peripheral surface of the device. In an excavating tool that is eccentric from the axis of the device, a surface having a horizontal component on a straight end surface of each block is
An excavating tool, wherein each of the straight end faces extends along a longitudinal direction of the straight end faces, and the straight end faces can be brought into contact with each other via a plane having these horizontal components. 2. The drilling tool according to claim 1, wherein the surface having the horizontal component forms a horizontal plane. 3. The excavating tool according to claim 1, wherein a plurality of surfaces having the horizontal component are provided along an axis of the device. 4. A protrusion protruding toward the straight end face of the other block on the straight end face of one of the pair of blocks is extended along a longitudinal direction of the straight end face, The excavating tool according to claim 3, wherein a concave portion that engages with the convex portion extends on the straight end surface of the other block.