JPH10169354A - Double-tube excavation device with extensible inner tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the working time and increase the excavation efficiency on connecting and recovering the drill pipe, by using an axially extensible inner tube. SOLUTION: An extensible inner tube 9 is constituted of a plurality of hollow pipes 9a-9d mutually fitted. When an excavation fluid is pumped to a supply passage of a swivel 1, as the fluid volume flowing in the inner tube 9 increases, the inner tube 9 stretches telescopically and the front end of the innermost peripheral hollow pipe 9d comes into contact with the front end pit 10 of the outer pipe 7 and stops there. And in this state, the ground is excavated by the rotation of the outer pipe 7. When excavation for one outer pipe 7 is completed and a new drill pipe is added and the inside of the inner tube 9 is evacuated through the supply passage 4, the fluid in the inner tube is sucked and the volume is reduced and the inner tube 9 is contracted and contained in the outer tube connection part 8. In this state, the outer tubes is additionally connected. In this way, the detaching work of the inner tube 9 is not required and hence, the working time is reduced and the excavation efficiency can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-pipe excavator having a telescoping inner pipe, and more particularly, to a double-pipe excavator suitable for excavating a hole at a relatively shallow depth for installation of an underground object. Drilling equipment.

[0002]

2. Description of the Related Art Drilling fluid is supplied to an inner pipe by using a drill pipe consisting of a double pipe in which an inner pipe is disposed inside an outer pipe having a bit at a tip, and a gap between the inner pipe and the outer pipe is provided. There is known a double pipe drilling rig that discharges cuttings by a drilling fluid stream discharged through the pipe. This double-pipe drilling device does not allow drilling fluid to flow through the outer periphery of the drill pipe as in the single-pipe method, and thus has the advantage of not causing collapse of the hole wall, particularly in an unconsolidated sedimentary layer.

However, in the double pipe drilling method, when connecting and collecting a drill pipe, the inner pipe and the outer pipe must be jointed and unthreaded simultaneously. For this reason, there is a problem that work is complicated in terms of weight and operation, and that much labor and time are required.

[0004]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the above technical background, and has the following objects.

[0005] It is an object of the present invention to connect and connect a drill pipe.
An object of the present invention is to provide a double-pipe excavator capable of eliminating the need for attaching and detaching an inner pipe at the time of recovery, shortening the operation time and improving the excavation efficiency.

[0006]

The present invention employs the following means to achieve the above object.

That is, the present invention provides a swivel having a supply passage and a discharge passage for a drilling fluid, wherein an inner pipe is connected so as to communicate with the supply passage, and an outer pipe is connected so as to communicate with the discharge passage. In a heavy pipe excavator, the inner pipe is formed of a telescoping pipe that can be telescopically extended in the axial direction.

Further, the present invention is characterized in that the telescopic inner tube expands by the fluid pressure of the drilling fluid supplied to the supply passage, and contracts by bringing the supply passage into a negative pressure state. In a double pipe drilling rig with

Further, the present invention provides a double-pipe excavator having a telescopic inner pipe, wherein a nozzle is provided at a tip of the telescopic inner pipe, and a check valve is provided behind the nozzle. is there.

Further, according to the present invention, a plurality of guide wings are provided on the outer periphery of the distal end portion of the telescopic inner tube, the guide wings being capable of contacting a bit provided at the distal end of the outer tube. A double-pipe excavator provided with the telescopic inner pipe as described above.

According to the present invention, since the inner pipe is made of a telescopic pipe, it may be extended as the excavation depth increases. By contracting the telescopic inner tube at the time of connecting / recovering the drill pipe, the work of attaching and detaching the inner tube becomes unnecessary. In other words, the attachment / detachment work involving screw connection / screw return only needs to be performed on the outer tube, and it is as if it were the same as the single tube system, and the operation time is greatly reduced. The telescopic inner pipe expands due to the fluid pressure of the drilling fluid and contracts when the inner pipe is made to have a negative pressure, so that the mechanism for the telescopic operation is very simple, and there is little trouble.

In the double pipe excavator according to the present invention, there is a limit to increasing the extension length of the telescopic inner pipe. Therefore, the present invention is mainly applied to relatively shallow excavation such as excavation for installation of an underground object. In other words, after excavation, the outer pipe is left on the ground as a casing, and water wells, anchors, earth rods, drainage materials for preventing liquefaction are buried in it, and then the underground buried object for collecting the casing is collected. It is suitable for drilling holes.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an axial sectional view showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a telescopic inner tube, and FIG. 3 is a sectional view taken along line AA of FIG.

The swivel 1 of the double pipe excavator comprises a swivel main body 2 and a seal case 3 provided on the outer periphery of the swivel main body so as to be relatively rotatable. A passage 5 is formed.
A drill head 6 is connected to one end of the swivel body 2, and a cylindrical outer pipe connection 8 is provided at the other end.
An outer tube 7 provided with a bit 10 at the tip is connected to an outer tube connecting portion 8 by a screw and communicates with the discharge passage 5. The configurations of the swivel 1 and the outer tube 7 as described above are the same as those in the related art.

According to the present invention, the inner pipe constituting the double pipe drill pipe together with the outer pipe comprises the telescopic inner pipe 9, which is connected to the swivel body 2 so as to communicate with the supply passage 4. As shown in FIG. 2, the telescopic inner tube 9 has a plurality of hollow tubes 9a.
9d are fitted to each other, and are fixed to the swivel body 10 by a screw portion 20 provided at the rear end of the outermost hollow tube 9a. The hollow tubes 9a to 9d adjacent to each other are movable in the axial direction, that is, the telescopic inner tube 9 is telescopic in a multistage (telescopic) manner. Although the number of hollow tubes constituting the telescopic inner tube 9 is four in this embodiment, the number is not limited.

Each hollow tube 9a except the innermost hollow tube 9d,
An annular engaging portion 11 is provided on the inner periphery of the distal end portion of each of the hollow tubes 9b and 9c, and each hollow tube 9 except the outermost hollow tube 9a is provided.
An annular engaging portion 12 engageable with the engaging portion 11 is provided on the outer periphery of the rear end of each of b, 9c and 9d. These engaging portions 11 and 12 are engaged with each other to prevent the hollow tubes from coming off.

Each hollow tube 9a except the innermost hollow tube 9d,
Snap ring 2 provided on the inner periphery of the rear end of 9b, 9c
1 is for positioning each hollow tube in a contracted state by engaging with the rear end of an adjacent hollow tube. The entire length of the contracted telescopic inner tube 9 is large enough to be stored in the outer tube connecting portion 8 of the swivel 1.

At the tip of the innermost hollow tube 9d, that is, at the tip of the elongated telescopic inner tube 9, a nozzle 13 as a throttle is provided.
Is provided. A check valve 14 is provided behind the nozzle 13, that is, on the upstream side in the flow direction of the drilling fluid. Normally, the valve body 15 of the check valve 14 is urged rearward by a spring 16 to abut against the valve seat 17 and its flow path 1
8 is closed.

Further, a plurality of guide vanes 19 are radially provided on the outer periphery of the distal end portion of the innermost hollow tube 9d. These guide vanes 19 have a length close to the inner circumference of the outer tube 7 when the telescopic inner tube 9 is extended, and can contact the bit 10 at the tip of the outer tube 7. The number of guide wings 19 is 4 in this embodiment.
Although there are at least two sheets, the number is not limited.

Next, the operation of the double pipe excavator will be described based on the method of use. As shown in FIG. 4, when a drilling fluid such as a liquid is supplied under pressure to the supply passage 4 of the swivel 1 by a fluid supply pump, the drilling fluid flows into the telescopic inner pipe 9, specifically, the innermost hollow pipe 9 d. I do. The drilling fluid that has flowed into the hollow pipe d opens the check valve 14 against the spring 16 and reaches the nozzle 13, but the nozzle 13 restricts the flow rate of the fluid discharged to the outside. And the fluid pressure becomes a force to extend the telescopic inner tube 9 by projecting the hollow tubes 9b, 9c, 9d.

As the volume of the fluid flowing into the telescopic inner tube 9 increases, the telescopic inner tube 9 expands in a telescopic manner,
The tip, that is, the tip of the innermost hollow tube 9d approaches the bit 10 at the tip of the outer tube 7, and the guide vane 19 comes into contact with the reduced diameter portion of the bit 10 and stops. The guide wings 19 serve to stabilize the telescopic inner tube 9 inside the outer tube 7 and to prevent it from protruding from the bit 10. As is apparent from the above description, the extension length of the telescopic inner pipe 9 is determined by the excavation depth, that is, the refill length of the outer pipe 7 until reaching the limit.

In this state, excavation is advanced by rotating or hitting the outer pipe 7. At that time, the drilling fluid blows out from the nozzle 13 to clean the periphery of the bit 10, returns to the swivel 1 through the gap between the outer pipe 7 and the telescopic inner pipe 9 with excavation, and It is discharged outside.

The connection operation of the drill pipe is performed as follows. When the drilling of one drill pipe (one outer pipe) is completed and a new drill pipe is to be added, the pumping of the drilling fluid is stopped and, as shown in FIG. A vacuum device such as a pump is connected, and the inside of the telescopic inner tube 9 is set to a negative pressure through the supply passage 4. At this time, since the check valve 14 is closed, the fluid in the telescopic inner tube 9 is sucked and the volume is reduced, whereby the expanded telescopic inner tube 9 starts to contract, and finally the swivel 1 It is stored in the pipe connection section 8.

In this state, the outer pipe 7 is refilled.
After the outer pipe 7 is added, the drilling fluid is supplied to the supply passage 4 as described above, and the telescopic inner pipe 9 is extended. in this way,
The screw connection operation for connecting the drill pipe may be performed only for the outer pipe 7 and is unnecessary for the inner pipe. Similarly, the unscrewing operation for collecting the drill pipe is unnecessary for the inner pipe.

The above embodiment is merely an example, and the present invention can be variously modified. For example, in the above embodiment, the outermost hollow tube is fixed to the swivel,
Conversely, the innermost hollow tube may be fixed to the swivel. In this case, the nozzle, the check valve, and the guide vane are provided in the outermost hollow tube. Further, in the above embodiment, the telescopic inner tube is constituted by a plurality of hollow tubes fitted to each other, but may be constituted by a bellows tube.

[0026]

As described above, according to the present invention, the work of attaching and detaching the inner pipe for connecting and collecting the drill pipe becomes unnecessary, and the working time can be shortened and the drilling efficiency can be improved. In addition, the number of drill pipes required for replenishment can be reduced, and the space for storing the drill pipes can be saved.

[Brief description of the drawings]

FIG. 1 is an axial cross-sectional view showing an embodiment of the present invention, and shows a state in which a telescopic inner tube is contracted.

FIG. 2 is an axial cross-sectional view showing the telescopic inner tube in an enlarged manner.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is an axial cross-sectional view of the telescopic inner tube in an extended state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Swivel 2 ... Swivel main body 3 ... Seal case 4 ... Supply passage 5 ... Discharge passage 7 ... Outer tube 8 ... Outer tube connection part 9 ... Telescopic inner tube 9a-9d ... Hollow tube 10 ... Bit 13 ... Nozzle 14 ... Reverse Stop valve 19: Guide wing

Claims (4)

[Claims] 1. A double pipe excavator, wherein an inner pipe is connected to a swivel having a supply passage and a discharge passage for drilling fluid so as to communicate with the supply passage, and an outer pipe is connected so as to communicate with the discharge passage. In the apparatus, the inner pipe is formed of a telescopic pipe capable of expanding and contracting in the axial direction. 2. The telescoping inner pipe according to claim 1, wherein the telescopic inner pipe expands by the fluid pressure of the drilling fluid supplied to the supply passage, and contracts by making the supply passage negative pressure. Double pipe drilling rig with pipe. 3. A nozzle is provided at a tip of said telescopic inner tube,
The double pipe excavator with a telescopic inner pipe according to claim 2, wherein a check valve is provided behind the nozzle. 4. The telescopic device according to claim 2, wherein a plurality of guide wings are provided on the outer periphery of the distal end of the telescopic inner tube so as to be able to contact a bit provided at the distal end of the outer tube. Double pipe drilling rig with inner pipe.