JP2021055273A - Head of boring casing - Google Patents

Abstract

To provide a head of a boring casing that can be replaced with a new boring blade and a tip surface at low cost even if the boring blade of the tip surface is worn to some extent, or the tip surface itself is worn or deformed.SOLUTION: A head 1 of a casing 20 for boring used for boring method includes a base portion 2 connected to a tip end side of the casing 20 and a tip end portion 7 positioned on a side of the tip end 3 of the base portion 2 and including a boring blade 6 on a tip end surface 8. The tip end portion 7 can be attached and detached to the base portion 2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a head attached to the tip end side of an excavation casing used when excavating a vertical hole in soil.

For example, when excavating a large-diameter vertical hole for pile driving, a cylindrical shape in which a plurality of excavating blades are attached along a ring-shaped tip surface on the tip (in the soil) side of a casing which is a vertically long cylindrical body. A head for a drilling casing that excavates a vertical hole by connecting the heads and rotating and settling the head together with the casing has been proposed (see, for example, Patent Document 1).

The head for the drilling casing is made of an integral piece of metal having a cylindrical shape as a whole, and a plurality of excavating blades are attached along the tip surface thereof. Along with the continuous excavation work, the tip surface of the head as well as the excavation blade is gradually worn by being subjected to frictional action with rocks and hard soil. Therefore, it is necessary to replace the entire head when the excavation blade is worn to some extent or the tip surface is worn or deformed. The head, which is subjected to a large stress due to the excavation work, needs to be formed of a material having higher mechanical rigidity than the casing. Therefore, the production of the head requires a high material cost and a high manufacturing cost due to the processing thereof. As a result, the cost required to replace the head may greatly increase the cost of the entire excavation work.

Japanese Patent Publication No. 4-57836 (pages 1 to 5, FIGS. 1 to 4)

The present invention solves the problems described in the background art, and even if the excavation member on the tip surface of the head is worn to some extent or the tip surface itself is worn or deformed, a new excavation member and tip can be obtained at low cost. An object of the present invention is to provide a head of an excavation casing that can be replaced with a surface.
Here, the excavation member refers to the above-mentioned excavation blade (cutter bit) and hardened overlay. The hardened overlay is an overlay performed by a molten metal in which molten metal and super-hardened particles are charged into the excavated surface of the casing head. The hardened overlay allows excavation without the use of excavating blades.

In order to solve the problem, as a result of diligent studies by the inventor, the present invention divides the head into a base portion on the casing side and a tip portion on the tip surface side, and makes the tip portion removable from the base portion. It was inspired by.
That is, the head of the casing for excavation according to the present invention is the head of the casing used in the excavation method, and has a base portion connected to the tip end side of the casing and an excavation member located on the tip end side of the base portion and having an excavation member on the tip surface. It is characterized in that it includes a tip portion, and the tip portion is removable from the base portion.

According to the head of the excavation casing, the head is composed of a base portion and a detachable tip portion. Therefore, when the excavation work due to the rotation of the casing and the subsidence in the soil is continuously performed, the excavation member attached to the tip surface of the tip portion of the head is worn out, or the ring-shaped tip surface at the tip portion Even if the casing is worn or deformed, after removing the tip from the base of the head, only the original excavation blade and the new tip with the tip surface can be connected to the tip side of the base. Can be reused for excavation work. Since the head is subjected to a large stress in the excavation work, the steel material constituting the head is required to have higher rigidity than the steel material constituting the casing. As a result, the material cost is high. According to the present invention, since only the tip portion is replaced, the material cost is significantly reduced as compared with the conventional example in which the entire head is replaced. Therefore, it is possible to reduce the cost required when replacing the head.

The casing is a single cylinder depending on the depth of the vertical hole to be excavated when driving a pile. Alternatively, it is a combination of a plurality of cylinders connected in the vertical direction.
Further, the head is a cylindrical body connected to the tip end side of the casing, rotates together with the casing, and an excavation member is attached along the circumferential direction on the tip end surface on the soil side.
Further, the tip portion of the head may be attached to and detached from the base portion and the hardened overlay of the head by, for example, being fixed by welding and detached by fusing.
In addition, the base of the head has a substantially cylindrical shape as a whole, and the tip of the head has a substantially ring shape as a whole.

Further, according to the second aspect of the present invention, the tip portion is screwed to the base portion by a screw member such as a bolt-nut. According to the head having such a configuration, since the tip portion is screwed to the base portion, the tip portion to be replaced can be easily and quickly removed from the base portion simply by removing the bolt used for the screwing. Moreover, the tip can be replaced simply by screwing a new tip to the tip side of the base. Therefore, the durability of the base and the head including the base can be enhanced, and the replacement work can be facilitated by maintaining the clearance between the male screw of the bolt and the female screw into which the bolt is screwed. Further, by screwing the tip portion and the base portion with a bolt-nut or the like, a mechanical clearance is generated, stress during excavation is relaxed, and its durability is improved.

As a structure for connecting the tip portion to the base portion, for example, at the end faces in contact with each other, a plurality of flanges extending from the periphery of one end face along the axial direction of both, and along the periphery of the other end face. Examples thereof include a form in which a hole that is formed and communicates with a plurality of recesses that individually receive the flange and is formed along the centripetal direction is formed, and a screw portion of a bolt is passed through the hole and screwed into a nut.

Further, according to the third aspect according to the present invention, the length of the base end surface and the tip end surface on the base portion side at the tip portion is in the range of 50 mm to 300 mm. More preferably, it is 150 to 300 mm. By setting the length of the tip portion to 50 mm to 300 mm, the deformation due to the excavation work can be limited to the tip portion only.
If the axial length between the base side and the tip surface of the tip is less than 50 mm, deformation due to excavation work may extend to the base. On the other hand, if the length exceeds 300 mm, the size becomes excessive and the production cost increases unnecessarily, which is not preferable.

(A) is a schematic view showing a usage state of the excavation casing including the head of the present invention, (B) is a partially enlarged view of a portion B in (A), and is a side view of the head. (A) is a front view showing the tip end surface side of the base portion of the head, and (B) is a side view of the base portion. (A) is a front view showing the tip end surface side of the tip end portion of the head, and (B) is a side view of the tip end portion.

Hereinafter, embodiments for carrying out the present invention will be described.
FIG. 1A is a schematic view showing a usage state of the excavation casing 20 including the head 1 of the present invention. As shown in the figure, a base machine (crane) 24 is arranged near the ground GL where a desired vertical hole should be excavated, and can be raised and lowered from the upper end of a vertical piece 25 supported by a plurality of arms extending from the machine 24. A vertically long casing 20 is suspended by a rope from a vertically long excavator 26, and a vertically long casing 20 is rotatable and settled in a protective cylinder 28 connected to the lower end of the excavator 26 via a motor, a speed reducer, and a chuck mechanism (not shown). It is arranged coaxially. The casing 20 is formed by connecting a plurality of unit casings 20a along the vertical direction, and the head 1 of the present invention is connected to the tip end (lower end in the drawing) side thereof. The unit casing 20a is a steel cylindrical body including a cylindrical hollow portion S.

As shown in FIG. 1B, the head 1 can be attached to and detached from the base portion 2 connected to the tip end (lower end in the drawing, the same applies hereinafter) side of the unit casing 20a located at the lowermost end, and to the tip end side of the base portion 2. It is composed of a tip portion 7 connected to the above.
As shown in FIGS. 2A and 2B, the base portion 2 is a processed steel material obtained by bending and welding a steel plate, and has a cylindrical shape including a hollow portion S1 having a cylindrical shape as a whole. A connecting ring 4 having a slightly smaller diameter is arranged at the end on the casing 20 side, and a plurality of recesses 5 are equidistantly spaced along the circumferential direction on the outer peripheral surface surrounding the tip surface 3 on the tip 7 side. Is formed in. Female screw holes 6 are individually bored in the central portion of the bottom surface of each recess 5 in a side view, and the outer end portion thereof is open.

On the other hand, as shown in FIGS. 3A and 3B, the tip portion 7 is a processed material made of the same steel, and the entire portion including the hollow portion S2 having the same inner diameter as the hollow portion S1 is a ring. ), And a plurality of excavating blades (cutter pits) 9 are provided on the tip surface 8 in the circumferential direction of the tip surface 8 via a holding portion 9a provided on the outer peripheral surface adjacent to the tip surface 8. A plurality of flanges 11 are provided at equal intervals along the axial direction on the base end surface 10 on the base 2 side. Female screw holes 12 or through holes 12 individually penetrate near the center of the side view of each of the flanges 11.
The length L along the axial direction between the tip end surface 8 and the base end surface 10 is set to 50 mm or more and 300 mm or less in advance.

As shown in FIG. 1 (B), the base portion 2 is integrally connected to the tip end side of the casing 20 via a connecting ring 4, and the base end surface of the tip portion 7 is connected to the tip end surface 3 side of the base portion 2. The 10s are connected so as to make surface contact. At this time, the casing 20, the base portion 2, and the tip portion 7 are coaxially continuous, and the hollow portions S, S1, and S2 are linearly communicated along the axial direction.

The detachable connection between the tip end surface 3 side of the base portion 2 and the base end surface 10 side of the tip portion 7 is preferably screwed using bolts and nuts, and both may be fully or partially welded. In the case of partial welding, it is possible to prevent the base portion 2 from being deformed by preferentially deforming the unwelded portion during excavation.
When the excavation blade remains on the base portion 2, the tip portion 7 can be attached to the excavation blade by welding after removing the flange 11. By preferentially deforming the unwelded portion of the tip portion 7 during excavation, it is possible to prevent the base portion 2 from being deformed.

As shown in FIG. 1 (A), a desired vertical hole can be excavated by rotating the head together with the casing 20 and sequentially submerging it toward the deep layer side in the soil. At this time, the soil scraped by the plurality of excavating blades 9 sequentially rises in the hollow portions S2 and S1 in the head 1 and in the hollow portion S in the casing 20, and is on the vertical hole side by the excavator 26. After being scraped upward from the ground, it is discharged to the right place on the ground GL.
If the above-mentioned excavation work is continued to some extent, the excavation blade 9 protruding from the tip surface 8 of the tip 7 of the head 1 is likely to be worn due to friction with rocks and hard soil layers in the soil, and the tip is easily worn. Since the surface 9 itself is likely to be worn or deformed, the excavation efficiency may decrease.

Therefore, when the excavation work is performed for a certain period of time, the casing 20 including the head 1 is once pulled up above the ground GL together with the excavator 26, and in this state, the base 2 of the head 1 is tipped. Remove from part 7.
Next, the base end surface 10 of the new tip portion 7 prepared in advance is attached at a position where the base end surface 3 of the base portion 2 comes into surface contact.

According to the head 1 of the excavation casing 20 of the form described above, the head 1 is composed of a base portion 2 and a tip portion 7 that can be attached to and detached from the base portion 2. Therefore, the wear deformation due to the excavation work is concentrated on the tip portion 7, and the change of the base portion 2 is prevented.
Further, since the length L between the base end surface 10 on the base portion 2 side and the tip end surface 8 in the tip portion 7 is within the range of 50 mm to 300 mm, even if the tip end surface 8 side of the tip portion 7 receives pressure in the soil. It is possible to suppress the situation of wear and deformation, and it is also possible to easily perform the work at the time of replacement.

Further, since the tip portion 7 is screwed to the base portion 2, the tip portion 7 to be replaced can be easily and quickly removed from the base portion 2 by simply removing the bolt 14 used for screwing, and a new tip portion can be removed. The tip portion 7 can be replaced simply by screwing the portion 7 to the tip surface 3 side of the base portion 2. Therefore, the durability of the base 2 and the head 1 including the base 2 can be enhanced by the clearance accompanying the screwing.

The present invention is not limited to the description of the embodiments and examples of the above invention. Various modifications are also included in the present invention as long as those skilled in the art can easily conceive without departing from the description of the scope of claims.

According to the present invention, even if the excavation blade on the tip surface is worn to some extent or the tip surface itself is worn or deformed, a new excavation blade and a head of the excavation casing that can be replaced with the tip surface at low cost can be provided. Can be provided.

1 …… Head 2 …… Base 3 …… Base tip surface 7 …… Tip 8 …… Tip tip surface 10 …… Tip base end surface 14 …… Bolt (screw)
20 ... Casing L ... Length

Claims (3)

The head of the casing used in the excavation method
A base connected to the tip side of the casing and
It is provided with a tip portion located on the tip end side of the base portion and having an excavation member on the tip surface.
The tip is removable with respect to the base.
The head of the excavation casing is characterized by that. The tip is screwed into the base,
The head of the excavation casing according to claim 1. The length of the base end surface on the base portion side and the tip end surface of the tip portion is in the range of 50 mm to 300 mm.
The head of the excavation casing according to claim 1 or 2.

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