JP2000104475A - Underground boring machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underground boring machine capable of conducting boring operation efficiently and quickly by fitting a casing pipe for covering a rotating shaft, and ejecting a fluid such as cement milk as a jet from the tip of a down hammer. SOLUTION: A rotating shaft and a down hammer are rotated in both normal and reverse directions by a rotating machine, and a casing pipe 50 is fitted to cover the rotating shaft. An excavation bit 60 provided on the down hammer is so constructed that three divided bit heads 70 are rotatably fitted to the tip of the bit with the respective divided surfaces opposite to one another in the mutual sliding contact state, and the diameter of rotation of each bit head 70 when the excavation bit is rotated in the normal direction is set larger than the outside diameter of the casing pipe 50, and when it is rotated in the reverse direction, the diameter of rotation is set smaller than the inside diameter of the casing pipe 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a casing pipe or a pile mounted so as to cover a rotating shaft, and a fluid such as water or cement milk can be jetted from a vicinity of a tip of a down hammer as a jet jet together with compressed air. Under such circumstances, the present invention relates to an underground drilling machine capable of efficiently and quickly performing a drilling operation.

[0002]

2. Description of the Related Art Conventionally, various types of underground drills are known, and as one form, the applicant of the present application has previously proposed an underground drill 10 'as shown in FIG. (See JP-A-8-240089). Hereinafter, this underground drilling machine 10 'will be briefly described. The illustrated underground drilling machine 10 ′ is configured to be able to jet a soil reinforcing material, such as water or cement milk, as a jet jet together with compressed air from the vicinity of a tip of a down hammer 5, which will be described later. A guide member 12 is provided at a side end of the guide member 12 and the top sheave block 15 of a pulley mechanism 14 disposed on the top of the guide member 12.
A rotary machine 4, a compressed air supply body 40 functioning as a rotary joint, a rotary shaft (auger screw) 3 provided with spiral blades, and a down hammer 5, And are integrally connected and suspended.

The rotating machine 4 includes a rectangular frame-shaped elevating housing 41, a geared motor 42, and a swivel device 44.
Consists of The elevating housing 41 is supported by two guide rails 18 provided on the front surface of the guide body 12 via a pair of upper and lower sliders 19 so as to be vertically movable. A geared motor 42 is provided in the lift housing 41.
Is connected to a swivel device 44 through which a fluid such as water or cement milk is introduced through a flexible conduit 45 from an external fluid supply device (not shown). A compressed air supply section 40 having a rotating shaft portion 47 is connected to the lower side of the swivel device 44, and the rotating shaft 3 is connected to the rotating shaft portion 47 via a coupling 49.

Then, compressed air is supplied from an external air compressor (not shown) to the compressed air supply unit 40 through a flexible conduit 46, and the compressed air supply unit 4
0 and the fluid such as water or cement milk from the swivel device 44 through the compressed air passage and the fluid passage (not shown) provided in the rotating shaft 3 and the down hammer 5. Hammer 5
Is guided to the vicinity of the tip of the excavation bit 7 and is ejected to the outside. The down hammer 5 is disclosed in, for example,
No. 166, which is conventionally known, in which compressed air sent through the compressed air passage and the fluid passage and fluid such as water or cement milk are mixed. And then eject it from the lower surface of the drill bit 7 to the outside in the form of a jet stream.

In addition to the above, in the underground drilling machine 10 ′, a casing pipe 50 is attached to a coupling 49 connected to a rotating shaft portion 47 of the compressed air supply unit 40 so as to cover the rotating shaft 3. I have. In the vicinity of the upper end of the casing pipe 50, a discharge port 50a for discharging excavated earth and sand outside the machine is provided. In this example, the lower end of the casing pipe 50 has a length reaching the vicinity of the lower end of the down hammer 5, but the lower end position is appropriately set according to the condition of the ground to be constructed. Further, an excavating head may be attached to the lower end of the casing pipe 50.

[0006] The underground drilling machine 10 'constructed as described above.
When the drilling operation is performed, the motor 42 is driven while the rotating shaft 3 and the down hammer 5 connected via the rotating machine 4 and the compressed air supply unit 40 are lowered. Thereby, the rotating shaft 3, the down hammer 5, and the casing pipe 50 descend while being guided by the guide rail 18 of the guide body 12 while rotating integrally. At this time, the compressed air from the external compressor is supplied to the compressed air supply unit 40 also functioning as a rotary joint through the flexible conduit 46, and passes through the rotating shaft 3 and the down hammer 5.
Is driven to vibrate the drill bit 7 in the vertical direction to perform a drilling operation similar to a normal drilling operation, and the casing pipe 50 is pushed into the drilled hole 100 at the same speed as the drilling speed.

The slime such as earth and sand generated at this time moves upward through the casing pipe 50 and is discharged from the discharge port 50a to the outside of the machine. Thereby, it is possible to reliably prevent the wall of the excavation hole 100 from collapsing. Further, by supplying water from the external fluid supply device at a predetermined pressure through the flexible conduit 45 during excavation, water is ejected from the lower end of the excavation bit 7 of the down hammer 5 together with compressed air as a jet jet, and the excavation bit 7 In addition to alleviating the friction and impact between the drill bit and the ground, the drill bit 7 is also cooled, so that the durability of the drill bit is improved, the environmental pollution due to noise and dust can be reduced, Efficiency can be increased. In the case where the soil of the ground where the drilling operation is performed is easily collapsed, if necessary, the fluid supply device including an external cement mixer or the like is operated, and the cement milk is compressed to a predetermined pressure through the flexible conduit 45. May be supplied. Thereby, an effect of preventing the excavation hole from collapsing can be obtained.

In the above-described underground drilling machine 10 ', a rotary shaft having a spiral blade and a down hammer are exemplified, but a drill without a spiral blade may be used depending on the excavation environment. After drilling to the required depth as described above, the casing pipe 5
While leaving 0, the rotating machine 4, the rotating shaft 3, the down hammer 5 and the like are raised and pulled out from the excavation hole 100 and the casing pipe 50. At that time, the casing pipe 50 also has a function as a pile.

[0009]

By the way, in the conventional underground drilling machine as described above, the diameter of the bit head 7a, which is the tip of the drill bit 7, is determined in consideration of pulling out from the casing pipe 50 upward. Therefore, the diameter is smaller than the inner diameter of the casing pipe 50, and is constant (unchangeable) at the time of drilling and at the time of pulling out.

Therefore, when the casing pipe 50 is pushed into the drill hole 100 drilled by the drill bit 7, the casing pipe 50 is susceptible to great resistance due to the wall of the drill hole. 7 did not move forward, and the drilling work was sometimes delayed and did not progress.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. An object of the present invention is to attach a casing pipe or a pile so as to cover a rotating shaft, and to make an arrangement near a tip of a down hammer. An object of the present invention is to provide an underground drilling machine capable of efficiently and quickly performing a drilling operation under the condition that a fluid such as water or cement milk can be jetted together with compressed air as a jet jet.

[0012]

In order to achieve the above object, an underground drill according to the present invention basically comprises a rotating machine, a compressed air passage through which compressed air flows, and water or cement milk. A rotary shaft having a fluid passage through which fluid such as fluid flows, and a down hammer having a drill bit are connected so as to be able to ascend and descend integrally, and the rotary shaft and the down hammer are moved in both forward and reverse directions by the rotary machine. A casing pipe or a pile is attached in a predetermined manner so as to be rotated and to cover all or a part of the rotation shaft.

[0013] The excavation bit is provided with a plurality of divided bit heads at the tip thereof, and the bit head is provided with an advancing posture larger than the outer diameter of the casing pipe or the pile, and Alternatively, it is characterized in that it can selectively take a retreat posture smaller than the inner diameter of the pile. The shape of the bit head is not particularly limited, but needs to be divided into two or three or more.

[0014] More specifically, the excavation bit has a plurality of divided bit heads rotatably attached to a tip end thereof via respective support shafts, and each of the bit heads is rotated by the rotating machine. When the drill bit is rotated in the forward direction, their rotation diameter is made larger than the outer diameter of the casing pipe or pile, and when the drill bit is rotated in the reverse direction by the rotating machine, Their rotational diameter is smaller than the inner diameter of the casing pipe or pile.

In a preferred aspect, the excavation bit has a predetermined angle interval such that a plurality of bit heads at the tip end face each other so that the divided surfaces can slide or separate from each other. Pivotally mounted, the respective bit heads are arranged such that, when the drilling bit is rotated in the forward direction by the rotating machine, the divided surfaces are closed or the divided surfaces are staggered. Are rotated so that their rotation diameters are larger than the outer diameter of the casing pipe or pile, and when the drill bit is rotated in the opposite direction by the rotating machine, between the divided surfaces thereof Are rotated in the direction in which the gap is formed or in the direction in which their divided surfaces increase the mutual contact area,
Their rotation diameter is made smaller than the inside diameter of the casing pipe or pile.

In this case, as a preferred specific example, three bit heads having the same dimensions and shapes are arranged at the tip end of the drill bit so that the divided surfaces each having an "H" -shaped cross section face each other. At a 120 ° interval. In another preferred embodiment, two semicircular bit heads are provided at the tip of the drill bit.
180 with the divided surfaces facing each other.
Attached so that it can be rotated at intervals

In the underground drilling machine according to the present invention having such a configuration, the diameter of the bit head of the drilling bit provided in the down hammer is such that when drilling (during drilling),
It is enlarged so as to be larger than the outer diameter of the casing pipe, and when it is pulled out, it is reduced so as to be smaller than the inner diameter of the casing pipe. It is possible to make the size as good as it corresponds to the diameter. Therefore, when pushing in the casing pipe or the pile, the resistance of the wall of the drill hole does not need to be much, and the casing pipe or the pile and the drill bit can be smoothly advanced, and the drilling operation can be performed efficiently and quickly.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of an underground drilling machine according to the present invention. Underground drilling machine 10 of illustrated embodiment
Is substantially the same as the underground drilling machine 10 'shown in FIG. 12 described above except for the excavation bit provided in the down hammer, and the portions corresponding to the respective parts of the underground drilling machine 10' have the same reference numerals. It is attached.

The underground drilling machine 10 of the illustrated embodiment is configured so that a soil reinforcing material such as water or cement milk can be jetted together with compressed air as a jet jet from the vicinity of the tip of a drill bit 60 provided in a down hammer 6 described later. A guide body 12 erected vertically at a front end of a base body 11, and a top sheave block 1 of a pulley mechanism 14 disposed on the top of the guide body 12.
The rotary machine 4, a compressed air supply body 40 functioning as a rotary joint, a rotary shaft (auger screw) 3 provided with spiral blades, and a down hammer through a buffer device 16 by a wire 17 hung from the wire 5. 6 and
Are integrally connected and suspended.

The rotating machine 4 comprises a rectangular frame-shaped elevating housing 41, a geared motor 42, and a swivel device 44.
Consists of The elevating housing 41 is supported by two guide rails 18 provided on the front surface of the guide body 12 via a pair of upper and lower sliders 19 so as to be vertically movable. A geared motor 42 is provided in the lift housing 41.
Is connected to a swivel device 44 through which a fluid such as water or cement milk is introduced through a flexible conduit 45 from an external fluid supply device (not shown). A compressed air supply section 40 having a rotating shaft portion 47 is connected to the lower side of the swivel device 44, and the rotating shaft 3 is connected to the rotating shaft portion 47 via a coupling 49.

Then, compressed air is supplied from an external air compressor (not shown) to the compressed air supply unit 40 through a flexible conduit 46, and the compressed air supply unit 4
0 and the fluid such as water or cement milk from the swivel device 44, through the compressed air passage and the fluid passage (not shown) provided in the rotary shaft 3 and the down hammer 6, Hammer 6
Passage 30 formed in drill bit 60 provided in
(Refer to FIG. 3) and mixed there, and the required number of radial fluid ejection passages 3 connected to the end of the mixing passage 30
Are ejected to the outside from 2, 32,... In the form of a jet stream.

In the underground drilling machine 10, a casing pipe (or a pile) 50 is attached to a coupling 49 connected to the rotating shaft portion 47 of the compressed air supply unit 40 so as to cover the rotating shaft 3. ing. In the vicinity of the upper end of the casing pipe 50, a discharge port 50a for discharging excavated earth and sand outside the machine is provided. The lower end of the casing pipe 50 is fixed to the outer periphery of the large-diameter portion 62 of the excavation bit 60 located near the lower end of the down hammer 6 via a cylindrical casing top 77. The basic configuration of the down hammer 6 is substantially the same as the conventionally known configuration described in, for example, JP-A-7-4166, but the configuration of the drill bit 60 provided therein is as follows. Unlike the conventional one, it is as follows.

That is, the excavation bit 60 is formed by the method shown in FIGS.
As can be understood from the above, the bit head 70, 70, 70 divided into three pieces having the same size and shape is provided on the front end face of the large-diameter portion 62 at the front end with a split surface having a cross-shaped "H" shape. 70a (FIGS. 5 and 6) are rotatably mounted at 120 ° intervals so as to be slidable against each other. More specifically, as shown in FIG. 3, each of the bit heads 70 has a columnar support shaft 75 protruding from the back surface thereof, and the support shaft 75 is formed at the large-diameter end portion 62. Annular groove portion 75 having a semicircular cross section and rotatably fitted in the bearing hole 72
a is locked by a locking pin 76 inserted into the large-diameter end portion 62 from the side, and each bit head 70 can rotate around the support shaft 75 as a rotation axis.

In this case, as shown in FIGS. 4 and 5, each of the bit heads 70, together with the rotating shaft 3, the down hammer 6, and the casing pipe 50, is provided with the excavating bit 60 by the rotating machine 4. Is rotated in the forward direction (the direction during excavation, the direction of the arrow P in FIG. 5),
Due to the rotational force (centrifugal force) and the excavation resistance, the triangular gap S is formed between the divided surfaces 70a of each bit head 70 as shown in FIG. The casing pipe 50 is rotated in a direction in which the casing pipe 50 is closed (a direction in which the gap S is eliminated) so that the rotation diameter thereof is larger than the outer diameter of the casing pipe 50.

On the other hand, as shown in FIGS. 6 and 7, when the excavating bit 60 is rotated by the rotating machine 4 in the opposite direction (direction at the time of pulling out, the direction of the arrow Q in FIG. 6), Due to the resistance of the hole 100, it is rotated in a direction in which a triangular gap S is formed between the divided surfaces 70a so that their rotational diameter is smaller than the inner diameter of the casing pipe 50. You. In addition,
Each of the bit heads 70 has a stepped shape with a small thickness on the outer peripheral side, and a large number of convex portions (bits) 74 are provided on the front side thereof in a predetermined arrangement. A required groove 63 is formed in the outer peripheral portion of the excavation bit 60 to allow the excavated earth and sand to pass upward.

The underground drilling machine 10 'constructed as described above.
When the drilling operation is performed, the motor 42 is driven to rotate normally while the rotating machine 4, the rotating shaft 3 connected via the compressed air supply unit 40, and the down hammer 6 are lowered.
As a result, the rotating shaft 3, the down hammer 6, and the casing pipe 50 descend while being guided by the guide rail 18 of the guide body 12 while integrally rotating in the forward direction. At this time, compressed air from an external compressor is supplied to the compressed air supply unit 40 which also functions as a rotary joint through the flexible conduit 46, and drives the down hammer 6 through the rotary shaft 3 to move the drill bit 60 in the vertical direction. By vibrating and performing a drilling operation similar to a normal drilling operation, the bit heads 70, 70, 7 of the drill bit 60 are simultaneously performed.
0 is the casing pipe 5 as shown in FIGS.
0, so that the diameter of the drill hole 100 formed by the drill bit 60 at the time of drilling is large enough to correspond to the diameter of the casing pipe 50. When the pipe 50 is pushed in, there is no need to receive much resistance due to the wall of the drilling hole, and the casing pipe 50 and the drill bit 60 advance smoothly, and the drilling operation can be performed efficiently and quickly. It is pushed into the drilled hole 100 at the same speed as the drilling speed.

The slime generated at this time, such as earth and sand, moves upward through the casing pipe 50 and is discharged from the discharge port 50a to the outside of the machine. Thereby, it is possible to reliably prevent the wall of the excavation hole 100 from collapsing. Further, by supplying water from the external fluid supply device with a predetermined pressure through the flexible conduit 45 during excavation, the water is compressed from the radial fluid ejection passages 32 formed in the excavation bit 60 of the down hammer 6. It is jetted as a jet jet together with air to reduce the friction and impact between the excavation bit 60 and the ground,
Therefore, the durability of the drill bit can be improved, the environmental pollution due to noise and dust can be reduced, and the drilling operation efficiency can be increased. If the soil of the ground where the drilling operation is to be performed is easily collapsed, the fluid supply device including an external cement mixer or the like is operated as necessary to
The cement milks may be supplied at a predetermined pressure through the air. Thereby, an effect of preventing the excavation hole from collapsing can be obtained.

In the underground drilling machine 10 of the present embodiment,
Rotary shaft with spiral blades, down hammer is illustrated,
Depending on the drilling environment, a drill without a spiral blade may be used. After drilling to the required depth as described above, as shown in FIG.
The rotating machine 4, the rotating shaft 3, the down hammer 6 and the like are lifted while the casing pipe 50 is left as a pile in 0, and the casing pipe 50 is pulled out from the excavation hole 100 and the casing pipe 50. At this time, when the rotating shaft 3, the down hammer 6, and the drill bit 60 are rotated in the opposite directions by the rotating machine 4, the rotating diameter of the bit heads 70, 70, 70 becomes smaller than the inner diameter of the casing pipe 50. Therefore, it can be pulled out without any trouble (see FIG. 7).

In the above-described embodiment, the drill bit 60 having the bit head 70 divided into three
However, the present invention is not limited to this, and the bit head may be divided into two or four or more. FIG.
FIG. 9 shows an example of a drill bit having two divided bit heads. In the drawings, the same reference numerals are given to portions (the fluid ejection passage 32, the large diameter portion 62, the support shaft 75, etc.) corresponding to the respective portions of the excavation bit 60 shown in FIGS. 5 and 6 described above. The drill bit 60A in the illustrated example has a semicircular shape of 2.
Each of the bit heads 80, 80 is provided with a support shaft 75, 75 serving as a rotation axis, similarly to the three-piece configuration described above. Reference numerals 80 and 80 denote face-like divided surfaces 8, respectively.
0a are brought into contact with each other so that they can slide on each other.
It is mounted so as to be rotatable at 80 ° intervals.

The two bit heads 80, 80, together with the rotating shaft 3, the down hammer 6, and the casing pipe 50 by the rotating machine 4, move the drill bit 60 ′ in the forward direction (the direction during drilling, When rotated in the direction of arrow P in FIG. 8), its rotational force (centrifugal force)
Due to the excavation resistance, as shown in FIG. 9, the divided surfaces 80a, 80a are substantially closed from each other in a direction along the divided surfaces (a state where the mutual contact area is relatively large), and FIG. As shown in the figure, the divided surfaces 80a are rotated so as to greatly differ from each other in a direction along the divided surfaces, and their rotational diameters are changed to the casing pipe 5.
0 is set to be larger than the outer diameter.

On the other hand, when the rotary machine 4 rotates the drill bit 60 ′ in the opposite direction (the direction at the time of pulling out, the direction of the arrow Q in FIG. 9), the drill bit 100 receives the resistance of the drill hole 100 and The divided surfaces 80a are rotated in a direction in which the divided surfaces 80a are made to coincide with each other along the divided surfaces, in other words, in a direction in which the mutual contact area is increased, so that their rotational diameters are smaller than the inner diameter of the casing pipe 50. To be. Therefore, the same operation and effect as described above can be obtained even when the excavation bit 60A divided into two and provided with the bit heads 80, 80 is used.

FIGS. 10 and 11 show another example of a drill bit having a bit head divided into two parts. In the drawings, the same reference numerals are given to portions (the fluid ejection passage 32, the large diameter portion 62, the support shaft 75, etc.) corresponding to the respective portions of the excavation bit 60 shown in FIGS. 5 and 6 described above. The illustrated excavation bit 60 </ b> B has two semicircular bit heads 90, 90.
Each of the bit heads 90, 90 is provided with a support shaft 75 serving as a rotation axis, similarly to the three-piece configuration described above. The divided surfaces 90a, 90a are rotatably mounted at 180 ° intervals so as to be opposed to each other in a detachable manner.

The two bit heads 90, 90 are rotated by the rotating machine 4 together with the rotating shaft 3, the down hammer 6, and the casing pipe 50 so that the excavating bit 60 'moves in the forward direction (the direction during excavation, When rotated in the direction of the arrow P in FIG. 10), its rotational force (centrifugal force)
Due to the excavation resistance, as shown in FIG. 11, the gap S is formed between the divided surfaces 80a, 80a (in front of each other), as shown in FIG. The gaps S between the divided surfaces 90a, 90a are eliminated so as to be in contact with each other, and the divided surfaces 90a are rotated so as to be largely staggered in a direction along the divided surfaces. It is made to be larger than the outer diameter of 50.

On the other hand, when the excavating bit 60B is rotated in the reverse direction (direction at the time of pulling out, the direction of the arrow Q in FIG. 11) by the rotary machine 4, the excavating bit 60B receives the resistance of the excavating hole 100 and splits them. The surfaces 90a, 90a are rotated in a direction in which the surfaces 90a are aligned along the divided surface, in other words, in a direction to increase the mutual contact area, so that their rotation diameters are smaller than the inner diameter of the casing pipe 50. To be. Therefore, the excavating bit 60B having the two divided bit heads 90, 90
In the case where is used, the same operation and effect as those described above can be obtained.

Although not shown, the front face of the drill bit is formed on a slope, and the bit head is slidably mounted on the slope. When the drill bit is lowered, the bit head is pushed up by the earth pressure and rises along the slope. The outer end of the casing pipe or pile is pushed outward from the outer diameter of the casing pipe or pile, and at the time of lifting, the outer end pushed outward is pushed inward due to friction with the surroundings and the inner diameter of the casing pipe or pile is raised. The same operation and effect as those described above can be obtained even when using the excavation bit that is set to the smaller retreating posture.

[0036]

As will be understood from the above description, according to the underground drilling machine according to the present invention, a fluid such as water or cement milk can be ejected from the vicinity of the tip of the down hammer as a jet jet together with compressed air. In such a case, the rotating diameter of the bit head of the drill bit provided in the down hammer is enlarged so as to be larger than the outer diameter of the casing pipe at the time of drilling (during the excavation), and at the time of withdrawal, at the time of pulling out, Is reduced so as to be smaller than the inner diameter of the drilling hole, so that the diameter of the drilling hole formed by the drilling bit at the time of drilling can be made as large as possible so as to correspond to the diameter of the casing pipe. Therefore, when the casing pipe is pushed in, the resistance of the drilling hole wall does not need to be much, so that the casing pipe and the drilling bit can be smoothly advanced, and the drilling operation can be performed efficiently and quickly.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an underground drilling machine according to an embodiment of the present invention at the time of drilling.

FIG. 2 is a diagram showing the underground drilling machine shown in FIG. 1 when it is pulled out.

FIG. 3 is an enlarged sectional view showing a drill bit portion of the underground drilling machine shown in FIG. 1;

FIG. 4 is an enlarged perspective view of a drill bit of the underground drilling machine shown in FIG. 1 when drilling.

5 is an enlarged bottom view (bottom view) of a drill bit of the underground drilling machine shown in FIG. 1 when drilling.

FIG. 6 is a bottom view (bottom view) of the underground drilling machine shown in FIG.

FIG. 7 is an enlarged perspective view of the excavation bit portion of the underground drilling machine shown in FIG. 1 when it is pulled out.

8 is an enlarged bottom view (bottom view) of another form of the excavation bit portion of the underground drilling machine shown in FIG. 1 at the time of drilling.

FIG. 9 is a bottom view (bottom view) of the underground drilling machine shown in FIG.

FIG. 10 is an enlarged bottom view (bottom surface) of another alternative form of the drill bit of the underground drilling machine shown in FIG.
FIG.

11 is a bottom view (bottom face) of the underground drilling machine shown in FIG. 1 when the drill bit is pulled out and shows another form of the drill bit portion in an enlarged manner.
FIG.

FIG. 12 is a schematic configuration diagram showing an example of a conventional underground drill at the time of drilling.

[Explanation of symbols]

 3-rotating shaft 4-rotating machine 6-down hammer 10-underground drilling machine 50-casing pipe 60, 60A, 60B-drill bit 70, 80, 90-bit head 70a, 80a, 90a-dividing surface S-gap

Claims (5)

[Claims] 1. A rotary machine, a rotary shaft having a compressed air passage through which compressed air flows and a fluid passage through which a fluid such as water or cement milk flows, and a down hammer having a drill bit are integrally moved up and down. And the rotating shaft and the down hammer are rotated by the rotating machine in both forward and reverse directions, and
In an underground drilling machine in which a casing pipe or a pile is attached in a predetermined manner so as to cover all or a part of the rotating shaft, the drilling bit has a plurality of divided bit heads attached to a tip end thereof. The bit head is characterized in that it can selectively take an advancing posture larger than an outer diameter of the casing pipe or the pile and a retreating posture smaller than an inner diameter of the casing pipe or the pile. And underground drilling machine. 2. A rotary machine, a rotary shaft having a compressed air passage through which compressed air flows and a fluid passage through which a fluid such as water or cement milk flows, and a down hammer having a drill bit are integrally moved up and down. And the rotating shaft and the down hammer are rotated by the rotating machine in both forward and reverse directions, and
In an underground drilling machine in which a casing pipe or a pile is attached in a predetermined manner so as to cover all or a part of the rotating shaft, the drilling bit is supported by a plurality of divided bit heads at a tip end thereof. The bit heads are rotatably mounted via shafts, and each of the bit heads has a rotation diameter larger than an outer diameter of the casing pipe or the pile when the drill bit is rotated in the forward direction by the rotating machine. The underground drilling machine is characterized in that, when the drilling bit is rotated in the reverse direction by the rotating machine, the rotation diameter thereof is smaller than the inner diameter of the casing pipe or the pile. 3. The excavation bit is rotated at a predetermined angular interval such that a plurality of bit heads at the tip end face each other in such a manner that the respective divided surfaces can slide or separate from each other. When the drill bit is rotated in the forward direction by the rotating machine, the respective bit heads rotate in a direction in which the divided surfaces are closed or in a direction in which the divided surfaces are staggered. The rotation diameter of the drill bit is made larger than the outer diameter of the casing pipe or pile, and when the drill bit is rotated in the opposite direction by the rotating machine, a gap is formed between the divided surfaces. Are formed, or their divided surfaces are rotated in a direction to increase the mutual contact area. The underground drilling machine according to claim 2, characterized in that the drilling is made smaller than the inner diameter of the pile. 4. At the tip of the drill bit, three bit heads having the same size and shape are arranged such that their respective split surfaces having a cross section of "H" are opposed to each other.
The underground drilling machine according to claim 3, wherein the drilling machine is rotatably mounted at intervals of 0 °. 5. A semicircular 2 at the tip of the drill bit.
4. The underground drilling machine according to claim 3, wherein the bit heads are rotatably mounted at 180 [deg.] Intervals so that the divided surfaces face each other.