JP2964734B2 - 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 for drilling in the ground by rotating a bit at high speed using fluid pressure.

[0002]

2. Description of the Related Art Conventionally, a drilling tool (turbo drill) for rotating a bit at a high speed using fluid pressure for drilling underground.
As an example, the one described in Japanese Utility Model Publication No. 62-33819 is known.

FIG. 12 is a sectional view showing the turbo drill, and reference numeral 1 in the figure indicates a turbo drill body. The main body 1 has a cylindrical shape, and an inflow port 2 of a mud is opened at an upper end side thereof. The mud flowing from the inflow port 2 drives the turbine 3. The turbine 3 has a large number of impellers 4a around a rotating shaft 4. The mud causes the rotating shaft 4 to rotate at a high speed via the impeller 4a. 4b is provided. One end of the bypass passage 4b is opened toward the inflow port 2, and a throttle 5 is attached to the opening 4c.

[0004] On the other hand, the other end of the bypass passage 4b is open to the outlet side of the turbine 3 so as to join with the mud exiting the turbine 3. On the outlet side of the turbine 3, a drive shaft 7 connected to the rotating shaft 4 of the turbine 3 is provided. The drive shaft 7 has a bit 8 attached to the other end.
And a passage 7a is formed at the center of the turbine 3 where the mud exiting the turbine 3 and the bypass passage 4b flows. The end of the passage 7a is communicated with the ejection hole 8a in the bit 8, and the mud flowing through the passage 7a is ejected forward of the bit 8 from the ejection hole 8a. The mud squirted in front of the bit 8 rises along with the soil excavated from the bit 8 through the annulus formed between the main body 1 and the well, and is discharged to the ground.

[0005]

However, in the turbo drill having the above structure, when the turbo drill is pulled out from the hole drilled after the end of the drilling, the outer peripheral surface of the tip bit comes into contact with the drilled hole. A frictional force is generated between the outer peripheral surface of the bit and the inner peripheral surface of the hole, which requires a relatively large force to pull out the turbo drill from the hole. If the bit is slightly tilted with respect to the axis, an excessive force acts on the bit from the inner peripheral surface of the hole, and the bit may be damaged. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a drilling tool that can be easily pulled out from a hole drilled after excavation with a small force.

[0006]

According to a first aspect of the present invention, there is provided an excavating tool comprising: a bit provided at a tip end portion of a tool body; Each of the block shafts is rotatably fitted around the axis in a point symmetry with respect to the center of the device, and a substantially semicircular shape having substantially the same diameter as the device is formed at the tip of each block shaft. The blocks on which chips are implanted on the surface are provided with the straight end faces facing each other, and the position of the block axis is changed when the device rotates in the excavation direction,
One end of each of the blocks protrudes from the outer peripheral surface of the device by a predetermined excavation amount, and at that time, the straight end surfaces of both blocks are eccentric from the center of the device so as to abut against each other , and further, The above devices have
An outlet hole for guiding and discharging the mud to the bottom of
At the end of the outlet hole, the outer periphery of the device
A notch opening in the surface is formed .

According to a second aspect of the present invention, there is provided an excavating tool, wherein at least three or more shaft holes are displaced from the center of the device on a bottom surface of the device connected to the drive shaft by disposing a bit provided at a tip portion of the tool body. And provided at equal angles in the circumferential direction,
The block shafts are rotatably fitted into the shaft holes, and a block having a substantially fan shape and a tip planted on the front end surface is provided at the front end portion of the block shaft. The arc portion is provided so as to form a substantially circular shape as a whole, and when the device is rotated in the excavation direction, the block rotates by the excavation resistance with the bottom of the excavation hole, and the one side end face of the block and the arc portion of the block are rotated. The relative position of the block axis with respect to the block is set so that the intersection protrudes from the outer peripheral surface of the device by a predetermined excavation amount, and at that time, both side end surfaces of each block abut against side end surfaces of adjacent blocks. The above device further comprises
An outlet hole for guiding and discharging the mud to the bottom
At the end of the outlet hole, outside the device.
A cutout is formed on the peripheral surface .

[0008]

According to the excavating tool of the present invention, when the device is rotated in the opposite direction to the excavation after the excavation is completed, the device rotates in the opposite direction to that during the excavation of the block and projects from the outer periphery of the device of the block. The ends of the holes are reduced so that they are close to each other and the block is located at or inside the bottom surface of the device, and the block is spaced from the inner peripheral surface of the drilled hole. Therefore, the drilling tool can be pulled out of the hole with a relatively small force, and even when the axis of the drilling tool is slightly inclined with respect to the axis of the hole at the time of pulling, a force acts on the bit from the inner peripheral surface of the hole. Without
Therefore, the breakage of the bit can be prevented. Also,
Lead-out hole that opens on the bottom of the device when the lock diameter is reduced.
Is temporarily closed by the block,
Has a notch formed in the outer peripheral surface of the device.
This allows the mud to blow out from this notch
Wear. This reduces the amount of debris between the device and the block.
It is possible to remove the resistance when the block diameter is reduced.
Can be.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a drilling tool according to the present invention will be described below with reference to FIGS. The difference between the excavating tool shown in these figures and the conventional excavating tool shown in FIG. 12 is the configuration of the bit. Therefore, only this configuration will be described, and the description of the other configurations will be omitted.

FIGS. 1 to 8 show a first embodiment of a drilling tool according to the present invention.
Indicates a bit. The bit 9 mainly includes a device 10 connected to the drive shaft 7 of the tool body 1 and a block 22 provided on the device 10. As shown in FIG. 2, the device 10 includes a small-diameter portion 10A having a spline groove 12 on the outer periphery and a block shaft 2
And a large diameter portion 10B provided with a shaft hole 11 into which a hole 0 is inserted. A discharge groove 14 is formed on the outer peripheral surface of the large diameter portion 10B to discharge the excavated chips upward.
An exhaust hole 15a extending in the axial direction is formed at the center of the device 10. The exhaust hole 15a opens at the upper end of the small diameter portion of the device 10, and the mud that drives the turbine 3 and the mud that flows through the bypass passage 4b flow in from this opening.

The flange 13 of the device 10
A peripheral groove 16a is formed on the outer peripheral surface of the device 10 located in the vicinity of the device 10 so as to make a full circumference in the circumferential direction of the device 10, and a communication between the peripheral groove 16a and the exhaust hole 15a is formed inside the device 10. A hole 16b is provided.

A pair of shaft holes 1 are provided on the bottom surface of the device 10.
1 and 11 are formed. The shaft holes 11 are formed so as to be shifted from the center of the device 10 and to be point-symmetric with respect to the center of the device 10. Shaft hole 1
The 1,11 are respectively inserted block shaft 20, 20 is freely and retaining rotating, retaining the or block shaft 20, for example, in a state where the block shaft 20 is fitted into the shaft hole 11 The locking pin 17 is inserted from the pin hole 18 of the device 10, and the locking pin 17 is engaged with a notch 20 a formed on the outer peripheral portion of the block shaft 20.

Next, the structure of the block shaft 20 and the block 22 will be described. The block shaft 20 and the block 22 are provided orthogonal to each other, and the block shaft 20 and the block 22 are formed integrally. Alternatively, they may be formed separately and connected by bolts or the like.

[0014] More specifically, the block shaft 20 is provided as shown in FIG.
As shown in FIG. 4, the length L is formed to be within a range of 1.5 to 2.5 times the outer diameter D of the block shaft 20. Has a cutout 20a into which the locking pin 17 is inserted.
The notch 20a is configured such that the outer periphery of the block shaft 20 is cut out only at a position corresponding to the angle at which the block 20 rotates, and the axial direction of the block shaft 22 is larger than the diameter of the locking pin 17. It has a basic structure that is notched long.

Meanwhile, each block 22, as shown in FIGS. 5 and 6, of the same shape formed in (semicircular shape in this embodiment) substantially sectorial bottom surface view, the radius of the fan devices It is set to a value substantially equal to the radius of 10. The blocks 22 are arranged such that the straight end faces 22a face each other and that the arc portions 22b of the blocks 22 form a substantially circular shape as a whole.

A first inclined surface 22c is formed on the outer peripheral portion of the distal end surface (bottom surface) of the block 22. The first inclined surface 22c is gradually inclined outward in the axial direction of the device 10 as it goes outward. A second inclined surface 22d that is inclined toward the base end side in the axial direction of the device 10 at an inclination angle different from that of the first inclined surface 22c is formed on the outer peripheral portion of the inclined surface 22c. These first inclined surface 22c and second inclined surface 22d
Is provided with a step 22f.
2, the thickness between the chips 21 implanted on the first inclined surface 22c and the second inclined surface 22 can be ensured, so that it is possible to implant a large number of chips 21.
Excavation efficiency can be improved. Device 1
When 0 rotates in the excavation direction, the end of the straight end face 22a of the block 22 that protrudes from the outer peripheral surface of the device 10 gradually toward the axially proximal end side of the device 10 as it goes forward in the rotation direction. An inclined third inclined surface 22e is formed. A plurality of chips 21 made of a hard metal are implanted on the tip surface of the block 22 and the first to third inclined surfaces 22c, 22d, 22e perpendicularly to the surfaces.

Here, when the device 10 is rotated, the outer peripheral side of the distal end face of the block 22 rotates at a higher speed than the center side, so that the chips 21.
A larger rotational reaction force acts from the excavated object. And
The resultant force F of the rotation reaction force and the reaction force of the impact force orthogonal to the reaction force acts on the tip on the outer peripheral side in an inclined manner. on the other hand,
The chip 21 has a high breaking strength with respect to a force perpendicular to the front end face of the block 22, but the strength is weakened as the force acts obliquely, so that the chip 21 is likely to be broken or dropped.

Therefore, in the above-mentioned excavating tool, the block 2
2, an inclined surface 22e is formed on the outer peripheral side.
Since the chips 21 are vertically implanted in the
As shown in FIG. 7, since they act substantially at right angles to the chips 21 on the outer peripheral side, it is possible to prevent the chips 21.

The outer circumference of each of the blocks 22 is formed by an arc having a different radius. That is, as shown in FIG. 5, the outer periphery of each block 22 is composed of two arcs S1, S2 and a curve S3 that smoothly connects these arcs S1, S2. The arcs S1 and S2 are arcs centered on the same point, and the radius of the arc S1 is the arc S2.
Is set to be larger than the radius. In addition, the arc S1
Is located on a side protruding from the outer peripheral surface of the device 10 when the device 10 rotates in the excavation direction, and the arc S
2 is located on the side that does not project.

A large number of chips 21 are implanted on the distal end surface of the block 22. However, since the radius of the outer periphery of the protruding side of the block 22 is larger than the radius of the outer periphery of the non-projecting side of the block 22, Many chips 2 on the protruding side
One can be planted. Therefore, device 10
When the work rotates in the excavation direction, even if the work amount of the protruding portion of the block 22 is large, a large number of chips 21
Is implanted, it is possible to prevent the chip 21 implanted in the protruding portion from being worn before the chip 21 implanted in the non-projecting portion wears out. The life as a drilling tool can be improved.

Next, the operation of the above-structured excavating tool will be described. When the mud flows from the inlet 2 of the tool body 1 to drive the turbine 2 to rotate the drive shaft 7 via the rotary shaft 4, the device 10 of the bit 9 connected to the drive shaft 7 rotates. . When the block 22 rotates in the excavation direction together with the device 10, the block 22 rotates around the block shaft 20 due to the excavation resistance, and
One end of the straight end face 2 protrudes from the outer peripheral surface of the device 10, and this portion functions as the outer peripheral blade A.

When the block 22 rotates,
The straight end faces 22a of the blocks 22 abut against each other, which serve as stoppers to restrict further rotation of the blocks 22. In this state, the block 22 receives the rotational force of the device 10 and excavates underground by the outer peripheral blade A or the like.

At this time, the mud exiting the turbine 3 and the mud flowing through the bypass passage 4b are
The excavated swarf which flows in from a and is blown out from the air hole (outlet hole) 15c and excavated is removed. Since the notch portion 15d in the front end of the air hole 15c is communicated with the discharge groove 14 is formed, flows as part of the mud is shown directly 8, efficient cuttings to assist the discharge of cuttings Can be removed.

After the excavation, the device 10
Is rotated in a direction opposite to the excavation direction. Then, the blocks 22, 22 rotate in the direction opposite to the direction of the excavation, the outer peripheral blades A, A are reduced in diameter so as to approach each other, and the arc portions 22b, 22b located at the outermost periphery of the blocks 22, 22 are formed.
Is equal to or inside the bottom surface of the device 10.

Therefore, when the drilling tool having the above configuration is pulled out from the drilled hole after the end of the drilling, the blocks 22, 22 of the bit 9 at the tip are separated from the inner peripheral surface of the drilled hole. No frictional force is generated between the holes 22 and 22 and the inner peripheral surface of the hole, so that the drilling tool can be pulled out of the hole with a relatively small force.
Even when the axis of the excavating tool is slightly inclined with respect to the axis of the hole during withdrawal, no force acts on the bit 9 from the inner peripheral surface of the hole because the blocks 22, 22 are separated from the hole. Can be prevented from being damaged.

When the blocks 22 are reduced in diameter as described above, the air holes 15c on the bottom of the device are not provided.
Is temporarily closed by the blocks 22 and 22 while the diameter of the blocks 22 and 22 is being reduced, but a notch 15d that opens to the side surface (outer peripheral surface) of the device 10 is formed at the tip of the air hole 15c. Therefore, the mud should be
By exhausting the mud to the contact surface between the device 10 and the block 22, excavation debris on these contact surfaces can be effectively removed. The resistance can be eliminated. 9 to 11 show a second embodiment. The digging tool of this embodiment is significantly different from the digging tool of the first embodiment in that three blocks are provided on the bottom surface of the device.

In the figure, reference numeral 31 indicates a bit. The bit 31 is mainly composed of a device 32 and three blocks 41 provided on the bottom surface of the device 32. On the bottom surface of the device 32, there are three shaft holes 3
Are formed at equal angles (every 120 degrees) in the circumferential direction of the device 32, shifted from the center of the device 32.

Block shafts 33 are fitted in the shaft holes 32a in a rotatable and locked manner. The retaining of the block shaft 33 is performed, for example, by using the block shaft 3
3 is fitted into the shaft hole 32a, a locking pin is inserted into the device 32 from the lateral hole, and the locking pin is inserted into the block shaft 33.
This is performed by engaging a ring-shaped recess 40 formed on the outer peripheral portion of the lens.

Reference numerals 41 indicate blocks provided at the ends of the block shafts 33 at right angles to the block shafts. The blocks 41 may be formed integrally with the block shafts 33 as in the first embodiment, or may be formed separately and connected with bolts or the like.

Each of these blocks 41 has the same shape and is formed in a substantially sector shape when viewed from the bottom, and the radius of the sector shape is set to substantially the same value as the radius of the device 32. Block 41
Are arranged such that the left and right side end surfaces 42a and 42b are opposed to each other, and that the arc portions 42c of the blocks form a substantially circular shape as a whole. The block 41 has left and right side end faces 42
The lengths a and b are formed to be different from each other, and the angles formed by the both end surfaces 42a and 42b are each 120 degrees.

The front end surface (bottom surface) of the block 41 is located on the block axis 33 side and orthogonal to the block axis 33, and descends from the arc-shaped ridge line of the plane 111 toward the outer peripheral side of the device 32. A first inclined surface 43 inclined at a gradient, and a second inclined surface 44 inclined at a downward gradient from the arc-shaped ridge line outside the first inclined surface 43 toward the outer peripheral side of the device 32, Moreover, a step 112 is provided between the first inclined surface 43 and the second inclined surface 44. Thus, by providing the step 112, the thickness between the chips 21 implanted on the first inclined surface 43 and the second inclined surface 44 can be ensured.
A large number of chips 21 can be planted, and the excavation efficiency can be improved.

When the device 32 is rotated in the excavation direction, the end of the side end surface 42a of the block protruding from the outer peripheral surface of the device 32 is provided with the axial base end of the device 32 gradually toward the front in the rotation direction. An inclined surface 45 inclined toward the side is formed. A plurality of chips 21 made of cemented carbide are implanted perpendicularly to the surfaces of the front end surfaces and the inclined surfaces 43, 44, 45 of the block.

The block shaft 3 for the blocks 41.
The relative positions of the blocks 41 are such that when the device 32 rotates in the digging direction, the blocks 41 rotate by the digging resistance with the bottom of the digging hole, and the one side end surface 42a of the blocks 41 The crossing portion protrudes from the outer peripheral surface of the device 32 by a predetermined excavation amount, and at this time, the side end surfaces 42b and 42a of each block are connected to the side end surface 42 of the adjacent block.
a, 42b.

The outer circumference of each of the blocks 41 is formed by arcs having different radii. That is, as shown in FIG. 11, the outer periphery of each of the blocks 41 is composed of two arcs S1 and S2 and a curve S3 that smoothly connects these arcs S1 and S2. Arc S1, S
Reference numeral 2 denotes an arc centered on the same point, and the radius of the arc S1 is set to be larger than the radius of the arc S2. When the device 32 rotates in the excavation direction, the arc S1 is located on a side protruding from the outer peripheral surface of the device 32, and the arc S2 is located on a side not projecting.

As described above, by setting the arc on the outer periphery of the block 41, as in the case of the first embodiment,
Before the chip 21 implanted in the portion of the block 41 that does not protrude from the outer periphery of the device 32 during excavation wears out,
It is possible to prevent the tip 21 implanted in the protruding portion from being worn out, so that the life of the excavating tool can be improved.

An exhaust hole 47 extending in the axial direction is formed at the center of the device 32. This exhaust hole 47 is opened at the base end face of the device 32, and from this opening,
Mud and bypass passage 4 driving the turbine 3
The mud that has flowed through b flows in. Further, in the device 32, horizontal holes 49 communicating with the distal end portion of the exhaust hole 47 and extending outward in the radial direction are formed at intervals of 120 degrees so as to pass between the shaft holes 32a. Side hole 49
An air hole (lead-out hole) 50 extending toward the distal end in the axial direction of the device 32 is communicated with the vicinity of the outer end of the device 32.
Notch 51 which is open to progressively spread Ri and an outer circumferential surface as it goes radially outwardly is formed in an opening portion that opens to a device bottom of 0. The outer end of the notch 51 is connected to a discharge groove 53 formed on the outer peripheral surface of the device 32 along the axial direction.

A communication hole 54 connected to the bottom of the shaft hole 32a is formed at the tip of the exhaust hole 47 of the device 32. A space 55 is formed between the bottom surface of the block shaft 33 and the shaft hole 32a. The space 55 includes a through hole 56 provided coaxially with each other and penetrating a central portion of the block shaft 32a, and the block 41. Through hole 5 penetrating up and down
It communicates with the bottom surface of the block through 7. A concave groove 58 formed along the bottom surface of the block 41 extends outward from the opening end of the through hole 57 that opens to the bottom surface of the block 41.

When the concave groove 58 is formed as described above, the mud blown out from the opening of the through hole 57 flows toward the discharge groove 53 along the concave groove 58, so that the excavation excavated by the chip 21 of the block 41 is performed. Debris can be removed more efficiently.

Next, the operation of the above-structured excavating tool will be described. When the mud flows from the inlet 2 of the tool body 1 to drive the turbine 2 to rotate the drive shaft 7 via the rotary shaft 4, the device 32 of the bit 9 connected to the drive shaft 7 rotates. . When the block 41 rotates in the excavation direction together with the device 32, the block 41 rotates around the block shaft 33 due to excavation resistance, and the block 4
The intersection of one side end surface 42a and the arc portion 42c protrudes from the outer peripheral surface of the device 32.
Function as

When the block 41 rotates,
The side end faces 42a, 42b of each block 41 abut against the side end faces 42b, 42a of the adjacent block 41, which function as stoppers to restrict further rotation of each block. In this state, the block 41 becomes the device 32
Under the ground, the underground is excavated by the outer peripheral blade A or the like.

Here, since the three blocks 41 are provided, the number of the outer peripheral blades A generated for one block 41 is naturally three, and the outer peripheral blades A are arranged at equal intervals in the circumferential direction. Is done. For this reason, well-balanced excavation can be performed, and even in the case of uneven ground, hole bending hardly occurs.

At the time of excavation, the individual blocks 41
As described above, the left and right side end surfaces 42a, 42b are in contact with the side end surfaces 42b, 42a of the adjacent block, respectively, and the block shaft 33 fixed to the block is fitted and supported in the shaft hole 32a. In conjunction with this, the block 41 is supported at three points. Accordingly, the individual blocks 41 are firmly fixed, and rattling is less likely to occur during excavation, and good excavation can be performed.

Further, at the time of excavation, when an excavation reaction force C parallel to one side end surface 42a is applied to one block 41 from the inner peripheral surface of the excavation hole as shown in FIG. Block shaft 33 integrated with the block
And the side end faces 42b, 42 that are in contact with each other.
It also acts on the other blocks 41 via a. Thus, even when a force parallel to one side end surface 42a of the block is applied, the force is applied to the block shaft 33 and the other block 41a.
And the load applied to one block shaft 33 is reduced accordingly. As a result, the load applied to one block shaft 33 can be reduced, and the advantage that the diameter of the block shaft can be reduced can be obtained.

The mud exiting the turbine 3 and the mud flowing through the bypass passage 4b flow into the exhaust hole 47, pass through the communication hole 54, the through holes 56 and 57, and block 41.
And the excavated swarf is removed from the block 41. Then, the excavated chips removed from the block 41 are discharged upward from the discharge groove 53 along the flow of the mud. Further, a part of the mud flowing into the exhaust hole 47 is blown out to the discharge groove 53 through the horizontal hole 49 and the air hole 20. Along with the flow of the mud, nearby excavated chips are sucked into the discharge groove 53, and the excavated chips are smoothly discharged.

After the excavation, the device 32
Is rotated in a direction opposite to the excavation direction. Then, the blocks 41 rotate in the opposite direction to the direction of the excavation, and the outer peripheral blades A...
Are located at the outermost periphery of the device 32 or equal to or inside the bottom surface of the device 32.

Therefore, when the drilling tool having the above configuration is pulled out of the drilled hole after the end of the drilling, the blocks 41 of the bit 31 at the tip are separated from the inner peripheral surface of the drilled hole. No frictional force is generated between the hole and the inner peripheral surface of the hole, so that the drilling tool can be pulled out of the hole with a relatively small force, and the axis of the drilling tool is aligned with the axis of the hole at the time of pulling out. Since the blocks 41 are separated from the holes even if they are slightly inclined with respect to
Thus, no force acts on the inner peripheral surface of the hole, so that breakage of the bit 31 can be prevented.

When the diameter of the block 41 is reduced as described above, the air hole 50 on the bottom surface of the device is temporarily closed by the block 41 while the diameter of the block 41 is reduced. Since the notch 51 that opens on the side surface of the device 32 is formed, the mud can be exhausted to the outside through the notch 51, and the mud can be blown out to the contact surface between the device 32 and the block 41. Thus, it is possible to effectively remove the excavation debris on the contact surface, and it is possible to eliminate the resistance when the block diameter is reduced.

In the second embodiment, the block 41
.. Are provided as an example, but the present invention is not limited to this, and the present invention is also applicable to those having four or more blocks. In the second embodiment, the left and right side end surfaces 42a, 42b of the blocks 41 are formed flat. However, the present invention is not limited to this, and the same side end surfaces 42a, 42b are formed in an arc shape that engages with each other. May be.

[0049]

As described above, according to the excavating tool of the first aspect of the present invention, when the device is rotated in the direction opposite to the excavation after the excavation is completed, the device is rotated in the direction opposite to that in the excavation of the block. The ends of the block that protrude from the outer periphery of the device are reduced in diameter so that they approach each other, so that the block is positioned equal to or inside the bottom surface of the device.

Therefore, when the excavating tool having the above configuration is pulled out from the drilled hole after the excavation is completed, the bit block at the tip is separated from the inner peripheral surface of the drilled hole. No frictional force is generated between the drilling tool and the peripheral surface, so that the drilling tool can be pulled out of the hole with a relatively small force, and the axis of the drilling tool is slightly inclined with respect to the axis of the hole at the time of pulling out. Also, since the block is separated from the hole, no force acts on the bit from the inner peripheral surface of the hole, so that breakage of the bit can be prevented. Also, when performing the block diameter reduction operation,
The open outlet hole is temporarily closed by the block,
At the end of the hole, there is a notch that opens to the outer peripheral surface of the device.
The mud blows out from this notch because it is formed
Can be made. This allows the device to
Effectively removes drilling debris and reduces the resistance when the block diameter is reduced.
Can be removed.

According to the excavating tool of the second aspect, the following effect can be obtained in addition to the same effect as the first aspect. At the time of excavation, there are three or more peripheral blades, each part of which protrudes outward from the peripheral surface of the device, and these peripheral blades are spaced at appropriate intervals in the circumferential direction. However, even when excavating a heterogeneous layer, hole bending is unlikely to occur and the excavation efficiency increases. At the time of excavation, each block is firmly supported at three points of the left and right side end surfaces and the block axis, and as a result, rattling during excavation of the block can be eliminated.

In addition, as described above, since there are a large number of outer peripheral blades and the individual blocks can be firmly supported, the tool life is extended. Even when a block excavation reaction force is applied in parallel to the side end surface, the excavation reaction force is distributed to the block shaft supporting the block and other blocks, thereby reducing the load applied to the block shaft. be able to.

The excavation reaction force applied to the blocks ultimately acts on the block shafts that support those blocks. However, since a plurality of block shafts are arranged on the bottom surface of the device in a well-balanced manner in the circumferential direction, the entire block is covered with a plurality of blocks. Support strength increases. Since three or more blocks are provided, the rotation angle of the block when the block shifts from the non-excavation state to the excavation state or vice versa is smaller than that of the block having only two blocks, and accordingly, The transition will be smooth. Further in accordance with the number of blocks, the discharge grooves formed on the device can also be provided a number, it is also improved discharge efficiency of cuttings.

[Brief description of the drawings]

FIG. 1 is a sectional view of a drilling tool according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a bit of the excavating tool according to the first embodiment.

FIG. 3 is a front view of a block of the excavating tool according to the first embodiment.

FIG. 4 is a sectional view showing an engagement state between a block and a locking pin of the excavating tool according to the first embodiment.

FIG. 5 is a plan view showing a state where the diameter of the block of the excavating tool according to the first embodiment is expanded.

FIG. 6 is a plan view showing a state where a block of the excavating tool according to the first embodiment is reduced in diameter.

FIG. 7 is a cross-sectional view of a main part during excavation of the excavation tool of the first embodiment.

FIG. 8 is a perspective view of a bit of the excavating tool according to the first embodiment.

FIG. 9 is a sectional view of a bit of a drilling tool according to a second embodiment.

FIG. 10 is a plan view showing a state where a block of the excavating tool according to the second embodiment is reduced in diameter.

FIG. 11 is a plan view showing a state in which the block of the excavating tool according to the second embodiment is expanded in diameter.

FIG. 12 is a sectional view of a conventional drilling tool (turbo drill).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tool main body 2 Mud inflow port 3 Turbine 7 Drive shaft 9, 31 bits 10, 32 Device 20, 33 Block shaft 22, 41 Block 21 Chip 22a Straight end surface 42a, 42b Side end surface

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Katsuaki Tsujimoto 1528 Nakashinda, Yokoi, Kobe-cho, Anpachi-gun, Gifu Prefecture Mitsubishi Materials Corporation Gifu Works (56) References JP-A-63-11789 (JP, A) JP-A-59-76391 (JP, A) JP-A-4-41891 (JP, A) JP-A-62-85592 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) ) E21B 3/00-4/20 E21B 10/00-10/66

Claims (2)

(57) [Claims] A mud flowing from a mud inlet of a tool main body rotates a turbine provided in the tool main body, and transmits the rotation of the turbine to a bit via a drive shaft. In a drilling tool to be excavated, the bit is fitted into a bottom surface of a device connected to the drive shaft so as to be rotatable around a block shaft in a point symmetry with respect to the center of the device, and each block shaft is At the tip of the device, a block having a substantially semicircular shape having substantially the same diameter as the device and having a tip implanted on the tip face is provided with the straight end faces facing each other, and the position of the block shaft is When the device rotates in the excavation direction, one end of each of the blocks protrudes from the outer peripheral surface of the device by a predetermined excavation amount, and at this time, the straight end surfaces of both blocks are alternated. By decentering the center of the device so as to abut configured to, the more the device, the bottom surface
If an outlet hole is provided to guide and discharge the mud to
In addition, the leading end of the outlet hole is opened on the outer peripheral surface of the device.
A drilling tool characterized by forming a cutout portion to be opened. 2. A mud flowing from a mud inlet of a tool main body rotates a turbine provided in the tool main body, and transmits the rotation of the turbine to a bit via a drive shaft. In a drilling tool for excavating, the bit is provided on a bottom surface of a device connected to the drive shaft, at least three or more shaft holes are offset from the center of the device and are equiangularly arranged in a circumferential direction. A block shaft is rotatably fitted in the hole, and a block having a substantially fan-like shape and a tip planted on the tip surface is placed at the tip of the block shaft. Parts are formed so as to form a substantially circular shape as a whole, and when the device is rotated in the excavation direction, the block rotates due to the excavation resistance with the bottom of the excavation hole, and the block rotates on one side end surface of the block. The relative position of the block axis with respect to the block is adjusted so that the intersection of the parts protrudes from the outer peripheral surface of the device by a predetermined excavation amount, and at this time, both end surfaces of each block abut on side end surfaces of adjacent blocks. Set up and configure , and the device has a bottom
With an outlet hole for guiding and discharging the mud,
At the end of the outlet hole, an opening is formed on the outer peripheral surface of the device.
An excavating tool characterized by forming a notch portion .