JPH0571287A - Excavation tool - Google Patents

Abstract

PURPOSE:To make it possible to surely reduce the diameter of a block. CONSTITUTION:The peripheral surface section of the base end of a block 22 is inclined so that it is gradually separated from the axis of a device 10 with the movement to the front end side of the block 22. In a state to widen a diameter of the block 22, the site of the base end side of the block 22 forms an inclined surface 22k positioned to the inside of a radial direction of a casing pipe 30 from the end thereof. When the block 22 is drawn up, the front end of the casing pipe 30 is brought into contact with the inclined surface 22k to exert a upward force to the surface, the component of the pressing force is directed to the axis side of the device 10, so that force (component of the pressing force) in addition to turning effort of the device 10 is acted on the block 22 through the inclined surface 22k. Accordingly, excavated waste held between straight ends is crashed to remove, so that diameter reduction can be surely made.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excavating tool used when excavating the ground or earth and sand in various constructions of anchors, various drilling wells, various foundation pile holes, etc. Regarding what can be reduced in diameter.

[0002]

2. Description of the Related Art Conventionally, as one of excavating tools for excavating the ground, earth and sand, the one disclosed in Japanese Patent Laid-Open No. 63-11789 is known. This drilling tool is, as shown in FIGS. 18 to 20, provided on the bottom surface of a device 2 which receives an impact force of a hammer (not shown) and a rotational force of a hammer cylinder 1 in a point symmetry with respect to the center of the device 2. 2 shaft holes 2
a, 2b are formed, and the block shafts 3a, 3b are fitted into the respective shaft holes 2a, 2b so as to be rotatable around the shafts and prevented from coming off, and at the tips of the respective block shafts 3a, 3b.
A block 5a having a substantially semicircular shape having a diameter substantially the same as that of the device 2 and having a large number of bits 4 ...
5b are provided so that their straight end surfaces 6a, 6b are opposed to each other, and the block shafts 3a, 3b are positioned so that when the device 2 rotates in the excavating direction, one end of each of the blocks 5a, 5b Both project from the outer peripheral surface of the device 2 by a predetermined amount of excavation, and at that time, the straight end surfaces 6a, 6b of both blocks are eccentric from the center of the device 2.

In the excavating tool, when the device 2 is rotated in the excavating direction X by the hammer cylinder 1 as shown in FIG. 20, the blocks 5a and 5b receive the excavating resistance and the block axes 3a and 3b are used as axes. While rotating, one end of the straight end surfaces 6a, 6b of the blocks 5a, 5b protrudes from the outer peripheral surface of the device 2 by a predetermined amount, and parts of the straight end surfaces 6a, 6b abut each other to cause the blocks 5a, 6b.
5b has stopped rotating, and in this state, blocks 5a and 5b
Receives the rotational force of the device 2, excavates the ground by the bits 4, and further advances the ground by the impact force of the hammer.

At this time, in the earth and sand excavated, the compressed air discharged when the hammer piston falls in the hammer cylinder 1 is blown out from the air holes 8a and 8b provided in the bottom surface of the device 2 to cause the excavation tool. After being separated from the tip, it moves to the inside of the excavation pipe 9 via the discharge groove 9a provided in the device 2, and is further discharged from there.

[0005]

In the excavating tool, after the excavation is completed, the hammer cylinder 1 is rotated in the opposite direction to rotate the device 2, but at this time, the blocks 5a and 5b are excavated. The hammer cylinder 1 rotates because it rotates in the opposite direction to that of the hammer cylinder 1 to reduce the diameter and separate from the peripheral wall of the drill hole.
Can be pulled out from the drill hole by pulling it up. However, when the cutting debris is sandwiched between the straight end surfaces 6a and 6b when the blocks 5a and 5b are reduced in diameter, the cutting debris reduces the diameter of the blocks 5a and 5b, that is, the straight end surfaces 6a and 6b slide. The movement could be obstructed and the diameter could not be reduced. The present invention has been made in view of the above circumstances, and an object thereof is to provide an excavating tool that can reliably reduce the diameter of a block.

[0006]

In order to achieve the above object, the excavating tool of the present invention is provided in a casing pipe so as to be rotatable about an axis and movable in an axial direction. The bottom surface of the device that receives the rotational force of the cylinder is rotatably fitted around the block shaft in a point-symmetrical manner with respect to the center of the device, and the tip of each block shaft has a diameter approximately equal to that of the device. Blocks each having a substantially semicircular shape of the same diameter and having a bit implanted in the tip surface are provided with their respective straight end surfaces facing each other, and the position of the block shaft is changed when the device is rotated in the excavation direction. One end of each of the two blocks projects from the outer peripheral surface of the device by a predetermined amount of excavation, and the straight end surfaces of the two blocks contact each other when the blocks are expanded in diameter. In a drilling tool eccentric from the center of the block, the base end surface outer peripheral portion of the block is inclined so as to gradually separate from the axis of the device toward the tip end surface side of the block, and the diameter of the block is expanded. In this state, a portion of the block on the base end surface side forms an inclined surface located inside the casing pipe in the radial direction from the end surface of the casing pipe.

[0007]

In the excavating tool of the present invention, when the device is pulled up and the block is pulled up, the tip end surface of the casing pipe comes into contact with the inclined surface and an upward pressing force acts. Faces towards the axis of the device,
In addition to the rotational force of the device, a force (component force of the pressing force) acts on the block via the inclined surface. Therefore, even if the cutting waste is sandwiched between the straight end surfaces of the block during the diameter reduction, the cutting waste is crushed between the straight end surfaces and removed from between the straight end surfaces, so that the diameter is surely reduced. be able to.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 17 show an embodiment of the present invention. Basically, the drilling tool shown in the figures is similar to the drilling tool shown in FIGS. The block shafts 20 are rotatably fitted around the bottom surface of the device 10 that receives the rotational force in a point-symmetric manner with respect to the center of the device 10, and the tip ends of the respective block shafts 20 are covered with the device 10. A block 22 having a substantially semi-circular shape with a diameter substantially the same as the diameter of the block 22 and having a bit 21 planted on the tip surface is provided with the respective straight end surfaces 22a facing each other. When rotating in the excavating direction, both blocks 2
Each one of the two ends of the device 10 protrudes from the outer peripheral surface of the device 10 by a predetermined amount of excavation, and the straight end surfaces 22a of the two blocks 22 contact each other when the block 22 is expanded. The basic structure is eccentric from the center.

However, in the present invention, as shown in FIGS. 1 and 2, the outer peripheral portion of the base end surface of the block 22 is gradually separated from the axis of the device 10 toward the front end surface side of the block 22. The greatest feature is the formation of an inclined surface 22k that inclines. The inclined surface 22k is formed at a portion of the outer peripheral portion of the base end surface of the block 22 that protrudes outward from the front end surface of the device 10 when the block 22 is in the expanded state, and is formed between the base end surface of the block 22 and the inclined surface 22k. The ridge portion is configured to be located radially inward of the excavation pipe (casing pipe) 30 from the end surface thereof.

As shown in FIGS. 1 to 3, the excavating pipe 30 is formed in a cylindrical shape having a size into which the device 10 is inserted, and the retaining pipe 3 is provided at the inner circumference of the tip thereof.
1 is fixed integrally. On the outer circumference of the retaining pipe 31, a flange portion 31a that abuts on the tip of the excavating pipe 30.
Is provided, and the flange portion 31a is welded to the tip of the drill pipe 30 by the welding portion S over the entire circumference. Further, the retaining pipe 31 is formed with a notch hole 31b extending in the axial direction thereof and communicating with the inside and outside of the retaining pipe 31, and the retaining pipe 31 and the excavating pipe are connected via the notch hole 31b. 30 and 30 are welded together by the welded portion S.

Then, when the device 10 is pulled up by the hammer cylinder 1, the tip end surface of the retaining pipe 31 of the drill pipe 30 comes into contact with the inclined surface 22k formed on the outer peripheral portion of the base end surface of the block 22. When 10 is pulled up, the retaining pipe 3
The pressing force from 1 acts upward. Since the inclined surface 22k is inclined so as to gradually separate from the axis of the device 10 as it goes toward the tip end surface side of the block 22, a component force directed toward the axis side of the device 10 acts on the inclined surface 22k. As a result, a force acts on the block 22 so as to move or reduce the diameter of the block 22 toward the axis of the device 10.

When the device 10 is pulled up, the device 10 is rotated by the hammer cylinder 1 in the direction opposite to that at the time of excavation, and the rotating force causes the block 22 to contract. Since the force via the surface 22k acts to reduce the diameter of the block 22, the block 22 is surely reduced in diameter due to the synergistic effect of the forces in the direction of reducing the diameter of these blocks 22. Even if the cutting waste is caught between the straight end faces 22a of the block 22 at the time of this diameter reduction, the inclined surface 2 is added to the block 22 in addition to the rotational force.
Since the force via 2k acts, the cutting waste is
It is crushed between 2a and removed from between the straight end faces 22a.
Therefore, when the diameter is reduced, the straight end surface 22 of the block 22 is
Since sliding between a is not hindered, the diameter can be reliably reduced.

Although the inclined surface 22k is a flat surface in the above embodiment, it may be formed by a curved surface which is convex or concave in the radial direction of the block 22. Further, in the excavating tool of the above-described embodiment, the distance L ₁ between the base end face of the block 22 and the tip end face of the retaining pipe 31 of the excavating pipe 30 during excavation (diameter expansion) is set within a predetermined range. In other words, immediately after the end of excavation, the bit 21 planted on the tip end surface of the block 22 bites into the bottom surface of the excavation hole, so that the block 22 does not easily rotate when the diameter is reduced. Therefore, before rotating the block 22, if the block 22 is pulled up and the bit 21 is pulled out from the bottom surface of the drill hole to some extent or separated from the bottom surface of the drill hole, the block 22 rotates easily. If the height of the bit 21 is L ₂ , the distance is
It is set to 3L ₂ ≦ L ₁ ≦ 12L ₂ . in this way,
By providing a gap between the base end surface of the block 22 and the tip end surface of the drill pipe 30 and setting the distance L ₁ as described above, the diameter of the block 22 can be more reliably reduced. Here, the range of L ₁ is set as described above, because when L ₁ is less than 3L ₂ , most of the bit 21 bites into the bottom surface of the drill hole even if the block 22 is pulled up, so the diameter reduction is made smaller. This is because it is difficult to perform, and when L ₁ exceeds 12L ₂ , the device 10 becomes long and the weight increases more than necessary.

Next, other main members of the excavating tool of this embodiment will be described. As shown in FIG. 4, the device 10
When the inner diameter (d) of the insertion hole 11 of the block shaft 20 provided on the bottom surface of the block 22 and the diameter of the block 22 are expanded (when one end of the straight end surface 22a of the block 22 projects from the outer peripheral surface of the device 10 by a predetermined amount). The ratio (d / l) to the distance (l) between the ends of the block is set within the range of 0.22 to 0.34, and on the other hand, the rotation angle α of the block 22 is It is set in the range of 10 ° to 35 ° with respect to the center line WZ of the line segment XY connecting the axis G of the shaft 20.

Further, as shown in FIG. 7, in order to dispose the block shaft 20 in the above range, the axis of the insertion hole of the block shaft 20 provided on the bottom surface of the device is located from the center position of the bottom surface of the device to the tip of the device. The distance (B) × (0.2 to 0.3) is set in the separated position. Here, the ratio (d / l) of the inner diameter (d) of the insertion hole 11 of the block shaft 20 and the distance (l) between the block ends when the block is expanded.
Is 0.22 or more is that the insertion hole 1 of the block shaft 20
If the ratio (d / l) of the inner diameter (d) of 1 and the distance (l) between the block ends when the block is expanded is 0.22 or less, the diameter of the block shaft 20 becomes small, and the block shaft 20
Of the insertion hole 11 of the block shaft 20 and the distance (l) between the block ends when the block is expanded. When the ratio (d / l) is larger than 0.34, the strength of the block shaft 20 can be increased, but the inner diameter d of the insertion hole 11 is increased, so that the device 1
This is because the thickness on the 0 side becomes thin, the durability of the device is lost, and the tool life is shortened.

Further, the rotation angle α of the block 22 is shown in FIG.
As shown in FIG. 6, the rotation angle α is set in the range of 10 ° to 35 ° with respect to the center line WZ of the line segment XY connecting the axis G of the block shaft 20. If the angle is smaller than 10 ° with respect to the center line W-Z of the line segment X-Y connecting the axis G of 20, the block 22 is likely to contract due to impact vibration during use. If the rotation angle α is larger than 35 ° with respect to the center line WZ of the line segment XY connecting the axis G of the block shaft 20, the distance m of the contact surface of the straight end face of the block 22 is present. Is short, and the overhang of the bit 21 becomes large, which causes a neck break.

Further, in the present invention, the axis of the insertion hole of the block shaft provided on the bottom surface of the device is the diameter (B) × (0.2 to 0.2) of the tip of the device from the center position of the bottom surface of the device.
The distance between the center of the device and the center of the device is set to the position separated within the range of 3) is the diameter (B) of the device tip.
This is because if the distance is not more than 0.2, the distance between the two block shafts 20 becomes too short, the shaft diameter of the block shaft 20 becomes small, and the block shaft 20 easily breaks. This is because if the distance from the device is within the range of the diameter (B) of the tip of the device × 0.3 or more, the distance between the outer periphery of the device and the insertion hole 11 becomes short and the device itself is apt to crack.

As shown in FIGS. 1 and 2, the device 10 has a small diameter portion 10A having a spline groove 12 on its outer peripheral surface and a large diameter portion 10B having an insertion hole 11 into which the block shaft 20 is inserted. The outer peripheral surface of the large-diameter portion 10B has a flange portion 1 that fits into the retaining pipe 31 provided on the inner periphery of the tip of the excavating pipe 30.
3 is integrally provided, and a discharge groove 14 for discharging excavation waste upward is formed.

An exhaust hole 15a extending in the axial direction is formed at the center of the device 10. The exhaust hole 15a is opened at the upper end of the small-diameter portion of the device 10, and the compressed air discharged when the hammer piston falls is introduced from this opening.

Further, the device 10 is formed with a communication hole 15b which communicates with the tip of the exhaust hole 15a and extends outward in the radial direction. The communication hole 15b is directed from both ends thereof toward the tip of the device 10. Further, an air hole 15c that extends to reach the bottom surface of the device shaft 10 and opens is formed. A notch 15d that communicates with the discharge groove 14 and the air hole 15c is provided between the bottom surface of the device and the outer peripheral surface of the air hole 15c.

Further, the flange portion 13 of the device 10
A peripheral groove 16a that makes one round in the circumferential direction of the device 10 is formed on the outer peripheral surface of the device 10 located in the vicinity of, and the peripheral groove 16a communicates with the exhaust hole 15a inside the device 10. A communication hole 16b is provided (see FIG. 1).

Further, a blow hole 16c reaching the upper surface of the large diameter portion 10B of the device 10 and opening is formed in the communicating hole 15b communicating with the exhaust hole 15a.
It is designed so that the compressed air does not escape and the hammer H does not stop when c is clogged. The blow hole 16c
2 is located outside the hammer H and opens, as shown in FIG. 2, so that the blow hole 16c is not blocked by the hammer H when the hammer H is lowered.

The insertion hole 11 is formed so as to be displaced from the center of the device 10 and point-symmetric with respect to the center of the device 10. More specifically, the insertion hole 11 is shown in FIGS. As described above, the axis G is from the center position C of the bottom surface of the device to the diameter (B) × (0.2 to 0.2.
It is set and provided in the position separated in the range of 3).

The block shaft 2 is inserted in the insertion hole 11.
No. 0 is rotatably fitted and retained so that the block shaft 20 can be prevented from coming off. For example, when the block shaft 20 is fitted into the insertion hole 11, the lock pin 17 is inserted from the pin hole 18 of the device 10. Is inserted, and the locking pin 17
Is performed by engaging with a notch portion 20a 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. Since the block shaft 20 and the block 22 are provided so as to be orthogonal to each other, the block shaft 20 and the block 22 may be integrally formed. Alternatively, it may be constructed separately and connected by bolts or the like.

More specifically, the block shaft 20 is shown in FIG.
As shown in FIG. 3, the length dimension L is formed to be within the range of 1.5 to 2.5 times the outer diameter D of the block shaft 20. 9 and FIG. 10, the notch 2 into which the locking pin 17 is inserted
0a is formed.

The notch 20a has a configuration in which the outer periphery of the block shaft 20 is notched only at a position corresponding to the rotation angle of the block 22, and the block shaft 20 has a diameter larger than the diameter a of the locking pin 17. 22 has a basic structure that is cut out long in the axial direction. In practice, the cutout portion 20a is set to have a diameter of about 1/3 of the outer diameter of the locking pin 17, more specifically, a size of 4 to 8 mm. is there.

On the other hand, each of the blocks 22 has the same shape and is formed in a fan shape (semicircular shape in the embodiment) when viewed from the bottom, and the radius of the fan shape is set to substantially the same value as the radius of the device 10. .. The blocks 22 are arranged such that the straight end surfaces 22a face each other and the arcuate portions 22b of the blocks form a substantially circular shape as a whole.

A first inclined surface 22c is formed on the outer peripheral portion of the tip end surface (bottom surface) of the block 22 and gradually inclines toward the axial base end side of the device 10 as it goes outward. On the outer peripheral portion of the inclined surface 22c, 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.

Further, when the device 10 rotates in the excavating direction, the end of the straight end face 22a of the block 22 protruding from the outer peripheral surface of the device 10 gradually increases in the axial direction of the device 10 toward the front in the rotating direction. A third inclined surface 22e that is inclined toward the base end side is formed (FIG. 11).
reference).

A plurality of bits 21 made of cemented carbide chips are planted vertically on the tip surface of the block 22 and the first to third inclined surfaces 22c, 22d and 22e. .. Incidentally, in the embodiment, a part of these bits 21 ... Is a straight end face 22a of the block 22.
Of the bits 22a located in the vicinity and planted along the straight end surface 22a, one end of each of the blocks 22 of the bits 22a near the straight end surface is excavated from the outer peripheral surface of the device by a predetermined amount. As shown in FIG. 11, the apex R of the bit (the bit on the third inclined surface 22e in the embodiment) located outside the circular arc portion 22b of the one block 22 at the position projected by the amount is a block as shown in FIG. It is located outward of the extension line AB extending along the curvature of the outer surface.

Further, in the embodiment, between the bottom surfaces (tip surfaces) of the blocks 22 and the straight end surface 22a, one end of each of the blocks 22 is a predetermined amount of excavation from the outer peripheral surface of the device 10. When protruding by an amount corresponding to each other, recesses 22f are formed in the center of the block 22 so as to be concentric with the device 10 at the center of the block 22.

In the embodiment, the concave portion 22f is composed of a circular bottom portion and a taper surface which is inclined as it goes upward from the bottom portion, but this shape is not limited to the embodiment. For example, the shape shown in FIGS. 14 and 15 may be used. By the way, in FIG. 14, only the tapered surface is formed, and in FIG. 15, the tapered surface is eliminated and the wall portion extending almost vertically from the bottom surface is formed.

Next, the operation of the excavating tool having the above construction will be described. As shown in FIG. 2 and the like, in order to mount the block 22 on the bottom surface of the device 10, first, the block shaft 20
The block 22 and the block 22 are integrated, and the block shaft 20 is inserted into the insertion hole 11 on the bottom surface of the device 10 so that the straight end surfaces 22a of the block 22 face each other.

Next, from the pin hole 18 of the device 10,
When the engagement pin 17 is inserted and fixed, the block shaft 20 engages with the engagement pin 17, and the block and the device are assembled as shown in FIG. This assembly is a simple operation in which the block shaft 20 is inserted into the insertion hole 11 of the device 10 and the engagement pin 17 is engaged, and the two block shafts 20 are locked by one engagement pin 17. Therefore, there is an effect that the workability can be improved.

In the excavating tool as described above, when the hammer cylinder receives the driving force and is rotated in the arrow X direction, the device 1
0, the block shaft 20 and the block 22 also integrally rotate in the same direction. Further, when a hammer piston arranged in the hammer cylinder is driven to apply a downward impact force to the device 10, the block 22 thrusts into the ground and the bit 21 excavates the debris due to the rotational force.

When the block 22 rotates in the excavation direction together with the hammer cylinder and the device 10, the block 2 is rotated.
2 rotates about the block shaft 20 due to excavation resistance, one end of the straight upper end surface of the block 22 projects 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 right upper end surfaces 22a of the blocks abut each other, and they function as stoppers to restrict further rotation of the blocks. In this state, the block 22 receives the rotational force of the device 10 and excavates the ground by the outer peripheral blade A and the like. At this time, because the hammer piston falls,
The compressed air flows in through the exhaust hole 15a and enters the air hole 1
The excavated cuttings blown out from 5c are removed. A cutout portion 1 communicating with the discharge groove 14 is provided at the tip of the air hole 15c.
Since 5d is formed, a part of the compressed air is directly generated in FIG.
The flow as indicated by the middle arrow can assist the discharge of excavation debris and efficiently remove the excavated debris.

Further, in the embodiment, as shown in FIGS. 16 and 17, when the hammer piston falls, a part of the compressed air passes through the communication hole 16b, flows into the circumferential groove 16a, and is exhausted to the outside. Therefore, the flange portion 13 of the device 10
There is an advantage that it is possible to prevent excavation debris from entering the lower surface (contact surface) and protect the device contact surface. Further, when excavating, each block 22 is formed with a concave portion 22f, and when the diameter of the block 22 is expanded, the concave portion 25 is formed at the center position thereof, so that the block 22 is hard to rock when drilling, As the rattling is less likely to occur during excavation, excellent excavation can be performed, and the component force Fa of the propulsive force generated in the recess 25 becomes the force Fb acting in the radial direction and acting on the outer peripheral blade A, as shown in FIG. As it works against each other, it is possible to effectively prevent neck breakage,
The tool life can be extended.

In the embodiment, a part of the plurality of bits 21 planted on the tip surface of the block 22 is located near the straight end surface of the block 22 and is planted along the straight end surface. And bit 21 near these straight end faces
Of the two blocks 22, the apex of the bit 21 located outside the outer surface of the one block 22 at a position where both ends of the two blocks 22 protrude from the outer peripheral surface of the device by a predetermined excavation amount, As shown in FIG. 11, since the block 22 is positioned outside the extension line AB extending along the curvature of the outer surface of the block, when an impact force is applied to the block 22 during excavation, the radial direction of the device 10 is increased. There is an advantage that the force can be applied in the outward direction and the force acting on the outer peripheral blade A can be loaded.

Moreover, since the bit 21 on the extension line AB can be directed outward, wear of the bit can be reduced and the tool life can be extended. is there. Further, when the piston in the hammer cylinder drops, the compressed air pushed out by the hammer piston flows into the exhaust hole 15a and is blown out from the blow hole 16c through the communication hole 15b, so that the air hole 15c at the tip of the device is softened. Even if there is a problem such as a layer or other factors causing blockage, compressed air will not be blown through the blow hole 16c.
Since it is blown out more, the operation of the piston does not stop, the drilling work is not impaired, and the work efficiency can be improved.

Further, due to the excavation as described above, the bottom surface of the device is reduced by the impact, or the length dimension of the device becomes smaller than the initial dimension due to reworking due to damage to the impact surface. Since the notch 22a into which the locking pin 17 is inserted is formed longer than the diameter of the locking pin 17 in the axial direction of the block shaft 20, even if the length dimension of the device 10 is shortened, Locking pin 1
The shearing force acting on 7 does not increase,
There is an advantage that the locking pin 17 can be prevented from being broken.

Moreover, in the embodiment, since the cutout portion 22a has a cutout structure in which only the rotation range of the block shaft 20 is cut, the cross-section loss of the block shaft 20 can be made small, and the block shaft 20 can be made smaller. There is also an advantage that the strength can be improved. Further, in the embodiment, a flange portion 30a that abuts on the tip of the excavation pipe 30 is provided on the outer periphery of the retaining pipe 31, and the flange portion 30a and the tip of the excavation pipe 30 are welded over the entire circumference, and the detachment is further performed. A cutout hole 31b extending in the axial direction and communicating with the inside and outside of the retaining pipe is formed in the stop pipe 31, and the retaining pipe 31 and the excavation pipe 30 are welded through the notch hole 31b. Therefore, the retaining pipe 31 and the excavating pipe 30 can be firmly and integrally fixed to each other. In particular, the retaining pipe 31 is welded at the position of the notch hole 31b communicating with the inside and outside of the retaining pipe 31. Since a tightening effect due to welding occurs in this portion, the retaining pipe 31 and the drill pipe 3
There is an advantage that 0 can be more firmly fixed.

After the completion of the excavation, first, the hammer cylinder is raised to pull up the device 10, so that the block 22 is pulled up to pull out the bit 21 from the bottom face of the excavation hole. Raise while rotating in the opposite direction. Then, each of the blocks 22 is rotated in the direction opposite to that during excavation, and the straight end surfaces 22a of the blocks 22 slide and contract to reduce the diameter. At this time, the inclined surface 22k formed on the outer peripheral portion of the base end surface of the block 22 is reduced. , The tip surface of the retaining pipe 31 of the excavation pipe 30 comes into contact,
An upward pressing force acts. Then, the block 22 is surely reduced in diameter by the component force of the pressing force directed to the axis side of the device 10 and the rotational force of the device 10, and the arcuate portion 22b positioned on the outermost periphery of the block 22 of the device 10 is formed. Placed on the bottom or inside.

During the diameter reduction operation of the block 22 as described above, the air holes 15c on the bottom surface of the device are
Although it is temporarily closed by the block 22 in the middle of the contraction of the compressed air, since the cutout portion 15d opening to the side surface of the device 10 is formed at the tip of the air hole 15c, the compressed air is discharged to the outside through the cutout portion 15d. It can be evacuated, and by blowing compressed air to the contact surface between the device and the block, it is possible to effectively remove the cutting debris on these contact surfaces, and to remove the resistance when the block contracts. There is an effect that you can.

[0046]

As described above, according to the excavating tool of the present invention, the outer peripheral portion of the base end surface of the block is inclined so as to gradually separate from the axis of the device toward the tip end surface side of the block, And, in the expanded state of the block, since the base end surface side portion of the block forms an inclined surface located inside the casing pipe in the radial direction from the end surface of the casing pipe, when the device is pulled up and the block is pulled up, The tip surface of the casing pipe abuts and a pressing force acts upward, but the component force of this pressing force faces the axis line side of the device, so the block diameter is reduced by this component force and the rotational force of the device. .. Even if the cutting waste is sandwiched between the straight end faces of the block at the time of this diameter reduction, the cutting force is not directly applied to the block because the force is applied to the block through the inclined surface in addition to the rotational force as described above. It is crushed between the end faces and removed from between the straight end faces. Therefore, when the diameter is reduced, the sliding between the straight end faces of the block is not obstructed, so that the diameter can be surely reduced.

[Brief description of drawings]

FIG. 1 is a half sectional view showing an entire excavating tool.

FIG. 2 is a cross-sectional view showing an entire excavating tool.

FIG. 3 is a cross-sectional view showing an enlarged state of the device.

FIG. 4 is a plan view schematically showing a state where the diameter of a block is expanded.

FIG. 5 is a view showing a state in which blocks are arranged at an intermediate position.
It is a top view similar to.

FIG. 6 is a plan view similar to FIG. 4, showing a state in which the block has a reduced diameter.

FIG. 7 is a plan view showing the bottom surface of the device.

FIG. 8 is a perspective view of a device and a block.

FIG. 9 is a front view of a block.

FIG. 10 is a sectional view showing an engaged state of a block shaft and a locking pin.

FIG. 11 is a plan view showing a state where the diameter of the block is expanded.

FIG. 12 is a plan view showing a state in which the block has a reduced diameter.

FIG. 13 is a sectional view of a block.

FIG. 14 is a cross-sectional view shown for explaining another shape of the concave portion on the bottom surface of the block.

FIG. 15 is a cross-sectional view shown for explaining another shape of the concave portion on the bottom surface of the block.

FIG. 16 is a side view shown for explaining the action of the contact surface between the device and the drill pipe.

FIG. 17 is a side view shown for explaining the action of the contact surface between the device and the drill pipe.

FIG. 18 is a cross-sectional view of a conventional drilling tool.

FIG. 19 is a plan view showing the bottom surface of the block.

FIG. 20 is a plan view showing the bottom surface of the block.

[Explanation of symbols]

 10 device 20 block axis 21 bit 22 block 22k inclined surface 30 drill pipe (casing pipe) 31 retaining pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuaki Tsujimoto 1528, Nakanisha, Yokoi, Kobe, Anpachi-gun, Gifu Pref., Mitsubishi Materials Corporation Gifu Factory

Claims (1)

[Claims] 1. A device provided on a casing pipe rotatably about an axis and movable in an axial direction and receiving a shock force of a hammer and a rotating force of a hammer cylinder, a point on a bottom surface of the device with respect to a center of the device. Symmetrically, the block shafts were respectively rotatably fitted around the shafts, and the tips of the block shafts were formed in a substantially semicircular shape having the same diameter as the device, and a bit was implanted on the tip surface. Blocks are provided so that their respective straight end faces face each other, and when the device is rotated in the excavating direction, the block shaft is positioned such that both ends of each of the blocks are predetermined excavation from the outer peripheral surface of the device. In a drilling tool that protrudes by an amount and is eccentric from the center of the device so that the straight end surfaces of both blocks come into contact with each other when the block is expanded, In the outer peripheral portion of the surface, the portion gradually inclined from the axis of the device toward the tip end surface side of the block, and in the expanded state of the block, the portion on the base end surface side of the block is the casing pipe. An excavating tool, characterized in that an inclined surface is formed which is located radially inward of the casing pipe from an end surface.