JP2000356084A - Casing head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a casing head which can be easily attached to and removed from a casing on site thus enhancing the efficiency of repair work for the casing head, and which can provide a fixed condition excellent in terms of strength. SOLUTION: This casing head 12 is divided into a casing-side annulus 13 and an end-side annulus 14 which are butted against each other, and recessed steps 18, 19 are circumferentially provided in butting positions on the outer peripheral surfaces of both annuli 13, 14. An arcuate connecting plate 15 circumferentially divided into plural parts is fitted into both recessed steps 18, 19 and is fastened to the casing-side annulus 13 and the end-side annulus 14 by means of bolts, whereby the casing-side annulus 13 and the end-side annulus 14 are freely removably interconnected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casing head provided at the tip of a casing for drilling underground with the casing.

[0002]

2. Description of the Related Art As shown in FIG. 5, an annular casing head 2 is attached to a tip of a casing 1 using a steel pipe. Has a structure in which a large number of drill bits 3 are fixed around the tip of the casing.
An auger screw is inserted into the inside of the casing, and the auger screw is rotated while applying rotation and vertical load to the casing 1, thereby excavating a circular hole with the bit 3 of the casing head 2, discharging the earth with the auger screw, and cutting into the ground. A hole is formed.

As shown in FIG. 5, the casing head 2 is attached to a conventional casing by fixing the casing head 2 to the front end of the casing 1 by welding 4,
A structure is adopted in which the casing head 2 is divided into upper and lower parts, and butted portions are fastened with bolts in the axial direction.

The casing head 2 needs to be repaired due to wear and damage of the bit 3 due to use. However, repairing the casing head while fixing it to the casing is a long object. Therefore, the casing head 2 is detached from the casing 1 for repair.

[0005]

However, in the former structure in which the casing head 2 is fixed to the casing 1 by welding 4, the tip of the casing 1 is blown off, the casing head 2 is removed, and then the casing 1 is connected to the casing 1. Since the welded portion of the casing head 2 must be melted, not only is it troublesome and time-consuming to repair the casing head 2, but also because the tip of the blown casing 1 does not have a right-angle accuracy, the casing head 2 must be melted again. There is a problem that right angle processing must be performed before fixing.

Further, the latter structure in which the butted portions are fastened with bolts from the axial direction is a complicated structure, which makes it difficult to operate the bolts on site and also causes cement milk or the like to be injected at the time of drilling around the bolts. And a problem that the bolt cannot be removed occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a casing head which can easily and easily attach and detach a casing head to and from a casing, thereby improving the efficiency of casing head repair work and obtaining a fixed state excellent in strength. Is to provide.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 is divided into a casing-side annular body and a tip-side annular body which abut each other, and butted on the outer peripheral surfaces of both annular bodies. Around the concave step at the side position,
An arc-shaped connection plate divided into a plurality of pieces in the circumferential direction is fitted over both concave steps of the casing-side annular body and the distal-side annular body, and the connection plate is fastened to the casing-side annular body and the distal-side annular body with bolts. By doing so, a configuration in which the casing side annular body and the distal end side annular body are detachably connected is adopted.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

As shown in the figure, a casing head 12 fixed to the distal end of a casing 11 is divided into a casing-side annular body 13 and a distal-side annular body 14 which abut against each other, and the two annular bodies 13, 14 are connected to two connecting plates. It is structured to be detachably connected by fastening with 15, 15 and bolts 16.

The casing-side annular body 13 is fixed coaxially to the tip of the casing 11 by welding, and the tip-side annular body 14 has a bit 17 fixed at the tip. 14 is provided with concave steps 18 and 19 at the abutting side position on the outer peripheral surface, respectively, and both concave steps 18 and 19 are separated by axial ridges 20 provided at positions sandwiching the axis. Have been.

The casing-side annular body 13 and the distal-side annular body 14 are cylinders having an outer diameter slightly larger than that of the casing 11 and an inner diameter substantially equal to that of the casing 11. Although the structure in which the tip ring 21 with the bit 17 attached to the tip is fixed by welding or the like is shown, an integrated structure in which a number of drill bits 17 are directly fixed around the tip may be employed.

In a state where the casing-side annular body 13 and the distal-side annular body 14 abut against each other, the two connection plates 15 fitted over the two concave step portions 18 and 19 are made of a metal plate having a sufficient thickness in terms of strength. A substantially semi-cylindrical shape having a circumferential length that fits between the ridges 20 and an axial height that fits into the total axial height of the two concave steps 18 and 19 of the two annular bodies 13 and 14 butted together. Formed in the biconcave stepped portion 18,
The thickness fits into 19.

Therefore, the casing-side annular body 13 and the distal-side annular body 14 are abutted in a state in which the phases of the ridges 20 are matched, and two connection plates 15 are fitted over the concave steps from both sides sandwiching the axis. The end of the connection plate 15 and the ridge 20 abut on the casing head 12 in the rotation direction, thereby forming a detent portion.

The connection plate 15 is provided with stepped bolt insertion holes 22 at a plurality of portions where the casing side annular body 13 and the distal end side annular body 14 overlap, and the casing side annular body 13 and the distal end annular body 14 are provided. A screw hole 23 into which the bolt 16 is screwed is provided at a position corresponding to each bolt insertion hole 22 of the connection plate 15 fitted in the concave stepped portions 18 and 19.

The casing head of the present invention has the above-described structure, and abuts the tip-side annular body 14 with the casing-side annular body 13 fixed to the tip of the casing 11 in a state where the phases of the ridges 20 are matched. The two connecting plates 15 are fitted from both sides sandwiching the axial center over the two concave steps 18 and 19 of the casing-side annular body 13 and the distal-side annular body 14, and the bolts 16 inserted into the bolt insertion holes 22 of the connecting plates 15. Is screwed into the screw hole 23 and fastened, the casing-side annular body 13 and the distal-side annular body 14 are coaxially coupled and integrated, and attached to the distal-side annular body 14 by rotating the casing 11 and applying a vertical load. A vertical hole is excavated in the ground by drilling with the bit 17. At this time, the auger screw inserted into the casing 11 causes the casing 11
In some cases, the inside is excavated to form a vertical hole in the ground.

When the casing head 12 needs to be repaired, the bolts 16 are detached from the screw holes 23 to remove the connection plates 15 on both sides. And only the distal ring 14 needs to be brought to the repair location.

As described above, the distal end side annular body 14 is connected to the casing side annular body 13 by the connection plate 15 and the bolt 1.
6, the work of attaching and detaching the distal-side annular body 14 can be easily performed on site, and the mounting accuracy of the distal-side annular body 14 can be maintained even when attachment and detachment are repeated.

[0019]

As described above, according to the present invention, concave steps are provided around the outer peripheral surfaces of the casing-side annular body and the distal-end annular body that abut against each other, at the abutting side, respectively.
An arc-shaped connection plate divided into a plurality in the circumferential direction is fitted over the two concave steps, and the connection plate is fastened to the casing-side annular body and the distal-side annular body with bolts, so that the casing-side annular body and the distal end are connected to each other. Since the side ring is detachably connected, the tip ring can be removed simply by loosening the bolts and removing the connection plate, eliminating the need for welding and fusing at the site, and removing and attaching work for repair of the tip ring. In addition to being easily and efficiently performed at the site, even when attachment and detachment are repeated, the right-angle attachment accuracy of the distal-end annular body can be maintained.

Further, since the two divided annular bodies are joined by fastening the connection plate and the bolts, a strong joining strength can be obtained, and the strength as the casing head can be sufficiently secured.

[Brief description of the drawings]

FIG. 1 is a front view showing a connected state of a casing head.

FIG. 2 is an enlarged vertical cross-sectional view of a main part showing a coupling state of a casing head.

FIG. 3 is an enlarged cross-sectional view of a main part showing a coupling state of a casing head.

FIG. 4 is an exploded perspective view of a casing head.

FIG. 5 is a front view showing a conventional casing head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Casing 12 Casing head 13 Casing side annular body 14 Tip side annular body 15 Connection plate 16 Bolt 17 bit 18 Concave step part 19 Concave step part 20 Protrusion 22 Bolt insertion hole 23 Screw hole

Claims (1)

[Claims] 1. An annular body is divided into a casing-side annular body and a distal-end annular body that abut against each other, and a concave step is provided around the outer peripheral surface of each of the annular bodies at the abutting side, and is divided into a plurality in the circumferential direction. An arc-shaped connection plate is fitted over both concave steps of the casing-side annular body and the distal-side annular body, and the connection plate is fastened to the casing-side annular body and the distal-side annular body with bolts, thereby forming a casing-side annular body. And a distal end side annular body detachably connected to the casing head.