JP3203966B2 - Drilling tools - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drilling tool used for various anchoring works and various well drilling works, and more particularly to a drilling tool generally called a down-the-hole bit.

[0002]

2. Description of the Related Art In various anchor works and the like, particularly when excavating a vertical hole by rotary impact excavation, an excavation tool generally called a down-the-hole bit may be used. This excavating tool has a cylindrical holder, and a plurality of blades are arranged on one end surface of the holder. Then, by locally moving the holder up and down while rotating the holder around its axis while one end face of the holder is directed downward and pressed against the ground, local crushing and shearing of the ground by the blade body are performed. Destruction occurs and excavation takes place.

[0003]

However, the down-the-hole bit is particularly disadvantageous in that it is difficult to secure an excavation hole because the excavation waste is low and excavation is easily caused because the excavation waste is low and the excavation hole is easily collapsed. It was considered unsuitable for excavation of collapsed strata. The present invention has been made in view of the above circumstances, and has as its object to facilitate excavation of a collapsed stratum using down-the-hole bits.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a device which is vertically erected and receives a rotational force about its axis and a downward impact force, and is attached to the lower end surface of the device, and the lower end is expanded. A cylindrical holder having a diameter, a plurality of blades disposed on a lower end surface of the holder, an ejection hole provided on a lower end surface of the holder to eject fluid downward, and an outer periphery of the holder And a discharge groove provided on a surface and discharging the fluid upward.

In particular, in the excavating tool of the present invention, the holder is inserted coaxially from below into a casing pipe having a cylindrical shape and an outer diameter equal to or less than the maximum diameter of the holder. The casing pipe is supported by the holder in a state where an inner peripheral surface of a lower end portion of the casing pipe and an outer peripheral surface of the holder are in contact with each other, and the casing pipe is located above a contact point with the holder. A discharge hole penetrating the side of the casing pipe is opened.
That you mouth is and its features.

[0006]

In the drilling tool of the present invention, the holder is inserted coaxially into the casing pipe, and the casing pipe is supported by the holder at its lower end.
Accordingly, since the casing pipe descends along with the holder in the drilling hole along with the excavation, the drilling hole wall is always covered with the casing pipe, and as a result, the collapse of the drilling hole wall is prevented by the casing pipe. .

Further, since the excavated chips reach the inside of the casing pipe through the discharge groove and are further discharged upward in the casing pipe, the excavating property of the excavated chips is improved. Further, since the cutting waste present outside the casing pipe reaches the inside of the casing pipe through the discharge hole,
With the presence of the casing pipe, the removability of excavation debris located outside the casing pipe does not decrease.

[0008]

Embodiments of the present invention will be described below in more detail with reference to the drawings. Reference numeral 1 denotes a holder. The holder 1 has a columnar shape, and is attached at its upper end to a lower end surface of a vertically erected device (not shown) so as to be coaxial with the device.

The lower end of the holder 1 is enlarged in diameter to form an enlarged diameter portion 1a.
Are formed, and a plurality of tips (blades) 2 are implanted on the lower end surface of the enlarged diameter portion 1a. Further, on the outer peripheral surface of the enlarged diameter portion 1a, discharge grooves 3 vertically penetrating the enlarged diameter portion 1a are formed at a plurality of locations (six locations in the present embodiment) at equal intervals along the circumferential direction of the holder 1. Have been.

Further, an air supply hole 4 is formed in the holder 1 from above along the axis thereof, and a lower end of the air supply hole 4 has
The upper end of the ejection hole 5 opening to the lower end surface of the enlarged diameter portion 1a is connected. In the case of the present embodiment, the ejection holes 5 are formed at three places, and the lower ends of the ejection holes 5 are formed on the lower end surface of the enlarged diameter portion 1a at equal intervals along the circumferential direction of the holder 1 and each of the ejection grooves 3 is formed.
Are arranged so as to open radially inward. Further, the lower end of the ejection hole 5 and the lower end of the discharge groove 3 located radially outward thereof communicate with each other via a concave portion 1b formed on the lower end surface of the enlarged diameter portion 1a.

The enlarged diameter portion 1a is slightly reduced in diameter at the upper end thereof, and a groove 6 having a further reduced diameter is provided in the upper end along the circumferential direction of the holder 1. .
The holder 1 is inserted coaxially from below into a cylindrical casing pipe 7. here,
The outer diameter of the casing pipe 7 is equal to or less than the maximum diameter of the enlarged diameter portion 1a.
It is desirable that a gap having a predetermined width H is formed between the gap and the maximum diameter. Further, in order to facilitate both the propulsion and self-support of the casing pipe 7 in the borehole, the gap H is more desirably in the range of 3 to 12 mm.

Further, the inner diameter of the casing pipe 7 is the same as the upper end of the enlarged diameter portion 1a, and an annular reduced diameter member (reduced diameter portion) 8 is provided at the lower end of the casing pipe 7. By inserting the upper end into the casing pipe 7 from below, it is fixed so as to be coaxial with the casing pipe 7. Here, the inner diameter of the reduced diameter member 8 is the same as the outer diameter of the groove 6, and the longitudinal width of the reduced diameter member 8 is the same as the vertical width of the groove 6.

By fitting the groove portion 6 and the diameter reducing member 8 together, the casing pipe 7 is held in a state in which the lower end inner peripheral surface is in contact with the upper end outer peripheral surface of the enlarged diameter portion 1a. Supported by

On the other hand, between the outer peripheral surface of the holder 1 and the inner peripheral surface of the casing pipe 7 above the enlarged diameter portion 1a,
A gap 9 is formed. Further, the casing pipe 7 is formed with a discharge hole 10 that penetrates the side surface of the casing pipe 7 and communicates the gap 9 with the outside of the casing pipe 7.

Next, the excavation using the excavating tool having the above configuration will be described below. When the rotational force around the shaft tip and the vertical striking force are transmitted to the device while the lower end surface of the holder 1 is pressed against the ground, the rotational force and the striking force are transmitted to the holder 1, and the holder 1 moves up and down and excavates. Rotate in the direction of rotation. As a result, local collapse and shear failure of the ground by the chip 2 occur, and excavation is performed.

Since the casing pipe 7 is supported by the holder 1, the casing pipe 7 also descends in the excavation hole together with the holder 1 during excavation. Therefore, the borehole wall is always covered with the casing pipe 7, and as a result, the collapse of the borehole wall is prevented by the casing pipe 7.
That is, according to the excavating tool having the above configuration, the excavation hole is always ensured regardless of the geology of the ground to be excavated.

Further, since the impact force received by the holder 1 is transmitted to the casing pipe 7 simultaneously with the excavation, the casing pipe 7 vibrates up and down during the excavation. Then, frictional resistance is generated between the outer peripheral surface of the casing pipe 7 and the hole wall of the drilling hole that comes into contact with the casing pipe 7, and the casing pipe 7 is easily self-supported. As a result, the drilling hole is more reliably secured. You.

On the other hand, compressed air (fluid) is supplied to the ejection hole 5 during excavation via the air supply hole 4, and this compressed air is further ejected downward from the ejection hole 5. As a result, the cutting waste reaches the gap 9 in the casing pipe 7 through the discharge groove 3 as shown by the arrow A in FIG. 1 and is further discharged upward through the gap 9. Therefore, the exclusion of excavated swarf is improved as compared with the case where the casing pipe 7 is not provided.

Further, excavated chips generated or accumulated especially outside the casing pipe 7 are sucked into the gap 9 through the discharge hole 10 as shown by an arrow B in FIG. Is discharged. Therefore, with the presence of the casing pipe 7, the exclusion of excavation debris located outside the casing pipe 7 does not decrease, and the exclusion of excavation debris is further enhanced.

As described above, according to the excavating tool of the above-described embodiment, the excavation hole is always ensured irrespective of the geology of the ground to be excavated, and the removability of excavation dust is high. That is,
The excavating tool of the above embodiment can be sufficiently used for excavating a collapsible stratum, which was conventionally unsuitable for a down-the-hole bit. When the excavation is completed, the holder 1 may be pulled up together with the casing pipe 7, or the process may be shifted to the next step with the casing pipe 7 and the holder 1 remaining in the excavation hole.

Instead of inserting the upper end of the reduced diameter member 8 into the casing pipe 7 from below, for example, as shown in FIG. The diameter reducing member 8 may be fixed to the lower end face of the groove 7 so as to be coaxial with the groove 6.

[0022]

As described above, according to the present invention, a drilling tool can be obtained in which a drilling hole is always reliably ensured regardless of the geology of the ground to be drilled, and the drilling tool has high rejection of drilling debris.

[Brief description of the drawings]

FIG. 1 is a partial side sectional view of a drilling tool showing one embodiment of the present invention.

FIG. 2 is a front view of a drilling tool showing one embodiment of the present invention.

FIG. 3 is a cross-sectional view of a joint portion between a casing pipe and a reduced diameter member according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Holder 1a Large diameter part 1b Concave part 2 Chip 3 Discharge groove 4 Air supply hole 5 Injection hole 6 Groove part 7 Casing pipe 8 Large diameter member 9 Gap 10 Discharge hole A, B Exclusion direction of excavation debris

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-169969 (JP, A) JP-A-4-237794 (JP, A) JP-A-5-263576 (JP, A) 161990 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) E21B 10/38 E21B 4/14 E21B 7/20

Claims (5)

(57) [Claims] 1. A device that stands vertically and receives a rotational force about its axis and a downward impact force, and a cylindrical holder attached to a lower end surface of the device and having a lower end portion having an enlarged diameter. A plurality of blades disposed on a lower end surface of the holder, an ejection hole provided on a lower end surface of the holder, for ejecting a fluid downward, and an ejection hole provided on an outer peripheral surface of the holder, and configured to supply the fluid. An excavating tool having a discharge groove to be discharged upward, wherein the holder is inserted so as to be coaxial from below into a casing pipe having a cylindrical shape and an outer diameter equal to or less than the maximum diameter of the holder, The casing pipe is supported by the holder in a state where an inner peripheral surface of a lower end portion of the casing pipe is in contact with an outer peripheral surface of the holder. Drilling tool discharge hole passing through the side surfaces of Gupaipu is characterized in that open. 2. A casing according to claim 1, wherein said casing pipe has a reduced diameter portion provided at a lower end portion of said casing pipe along a circumferential direction thereof, and a groove provided at an outer peripheral surface of said holder along said circumferential direction. The excavating tool according to claim 1, wherein the excavating tool is supported by the holder by a diameter of the drilling tool. 3. The excavating tool according to claim 2, wherein the reduced diameter portion has a cylindrical shape, and at least an upper end portion of the reduced diameter member is coaxially inserted into the casing pipe. . 4. The excavating tool according to claim 2, wherein the reduced diameter portion is formed of a reduced diameter member having a cylindrical shape and fixed coaxially to a lower end surface of the casing pipe. 5. A drilling tool according to claim 1, wherein the fluid is air.