JPS589231B2 - Sliding type bottom expansion method bit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a slide-down type bottom-expanding method bit used in a bottom-expanding pile hole excavation method.

An object of the present invention is to enable the drilling method of expanding pile holes without destroying the hole wall stabilizing membrane and, therefore, without the risk of collapse of the hole wall in the expanded bottom part, and to allow the sliding bit to be raised and lowered at will. The object of the present invention is to provide a remotely controllable sliding type bottom-expanding construction bit.

Conventionally, a bottom-expanding method bit as illustrated in FIGS. 1A and 1B has been used in the bottom-expanding pile hole excavation method.

This has a tip bit 3 at the tip of a drill pipe 1 having a stabilizer 2, and also has wing-spreading bits 5, 5 which are laterally expanded by hydraulic cylinders 4, 4.

The tip bit 3 has a vertically downwardly directed cut 3a.

The wing-spreading bit 5 has hooks 5a facing outward in the horizontal direction.

The wing expansion bits 5, 5 rotate around pins 6, 6 at the upper part thereof, and expand like an umbrella (FIG. 1B) or contract (FIG. 1A).

An example of a conventional method for drilling a pile hole with an expanded bottom using the above-mentioned bottom expanding method bit is shown in FIGS. 2A, B, and C.

FIG. 2A shows a stage in which pile holes 7 of equal diameter have been excavated to a predetermined depth.

For the excavation, the bottom-expanding method bit is in a contracted state as shown in FIG. 1A, and the tip bit 3 is used to perform turning and drilling.

8 in the figure is a ground stabilizing liquid such as bentonite mud.

FIG. 2B shows a stage in the process of forming the enlarged bottom portion 9 at the lower end of the pile hole 7.

To form this, the bottom expansion method bit is rotated in the opposite direction with the tip bit 3 in contact with the bottom of the hole, and the expansion bits 5, 5 are gradually expanded by hydraulic cylinders 4, 4 to cover the entire height of the bottom expansion part 9 at once. This is done by shape turning.

FIG. 2C shows a stage in which the formation of the enlarged bottom portion 9 has been completed.

That is, turning is continued until the wing expansion bits 5, 5 are expanded to a predetermined angle to reach this stage.

The disadvantage of the conventional bottom-expanding method bit shown in FIG. At the point of shape turning.

In other words, a stable film of bentonite or the like may be formed over the entire range of turning to form the enlarged bottom portion 9, or even if it is formed temporarily, it will be destroyed (turned) one after another. This is because the hole wall of the turned portion (expanded bottom portion 9) is likely to collapse.

If the hole wall of the expanded bottom portion 9 collapses, it is not possible to create an expanded pile with a desired shape, which is why it is not practical.

This invention was made for the purpose of solving the above-mentioned drawbacks of the conventional widening method bit.

That is, the gist of the configuration of the present invention is that a tip bit is attached to the tip of a drill shaft, a bottom expanding guide fixed to the drill shaft and having a predetermined inclination, and a bottom expanding guide located above the tip bit and extending along the bottom expanding guide. This is a sliding-type wide-bottom construction bit consisting of a sliding bit that can be raised and lowered by lifting the sliding bit, and a jack that raises and lowers the sliding bit.

In this invention, the inclination of the enlarged bottom guide is made equal to the inclination of the enlarged bottom portion.

Further, the jack may be of any type as long as it can raise and lower the sliding bit by remote control, and although the illustrated example uses a hydraulic cylinder, it is not limited to any structural type.

Next, embodiments of the invention will be described.

Figures 3 and 4 show the sliding bottom expansion method according to the present invention. An example of a bit is shown.

In the figure, 10 is a drive pipe that transmits rotation to the bottom expansion method bit by a ground drilling machine, and 11 is a drill shaft connected to the lower end of the drive pipe.

A fishtail blade 13 is attached to the lower end of the drill shaft 11 facing downward.

Further, at the lower end of the same drill shaft 11, there are three tip bits l-
1 4. 14.14 are attached at positions that divide the circumference into three equal parts (Fig. 4).

A large number of hooks 14a, . . . are attached to the tip bits 14, 14, 14 downward in the counterclockwise direction in the figure.

Next, the three enlarged bottom guides 15, 15.15 are welded to the drill shaft 11 at the intermediate position of the tip bit 14, which is also a position where the circumference is divided into three (Fig. 3). Fixed.

The expanded bottom guides 15, 15, 15 have a guide plate 15
a is the taper of the enlarged bottom part 9 to be formed (dog body 11° to 1
2°).

Each of the above-mentioned bottom expansion guides 15... has its guide plate 15
A carriage 17 that can freely slide while holding a is attached, and a sliding bit 18 is attached to each carriage 17.
・is installed.

Each sliding bit 18 extends in the radial direction with a camber angle approximately equal to that of the tip bit 14.

In the illustrated example, a large number of cutters 18a are attached in the opposite direction to the cutter 14a of the tip bit 14, that is, downward in the clockwise direction in the figure (FIG. 4).
It goes without saying that the cutter 18a may be provided in the same direction as the cutter 14a.

The sliding bit 18 has an outer diameter that is the same as or smaller than the outer diameter of the tip bit 14 when located at the upper end of the bottom expansion guide 15.

Next, reference numeral 20 in the figure is a hydraulic fluid jack, and the upper end of the cylinder is attached to a platen l-
21. 21 and is supported by a pin 22.

Further, the tip end of the piston rod of the fluid jack 20 is individually connected to each sliding bit 18 by a pin 19.

In the figure, 23 is a stabilizer attached to the rear part (directly above) of the tip bit 14 in a position equal to the diameter of the pile hole 7;
25 is a stabilizer attached to the rear part of the downhill bit 18 at an angle equal to that of the bottom expansion guide 15, and 25 is a stabilizer placed above the downhill bit 18 with the drill shaft 11 as its center, the diameter being equal to the diameter of the pile hole 7.

Both stabilizers slide inscribed on the pore wall surface and assist in the formation of a stable film.

Next, a method of using the sliding type bottom expansion method bit and a bottom expansion pile hole drilling method using the same will be explained.

(i) Excavation of pile hole 7 (Figure 5A).

First, by contracting the fluid jack 20, the downhill bit 18 is positioned at the upper end of the expanded bottom guide 15, resulting in the state shown in FIG.

Then, the tip bit 14 is drilled in the drilling direction (counterclockwise direction in FIG. 4) by the ground drilling machine through the drive pipe 1.
Rotation and downward thrust are applied to the pile holes 7 of uniform diameter as shown in FIG. 5A to be excavated to a predetermined depth.

(11) Formation of the enlarged bottom portion 9 (FIGS. 5B and 5C).

When the pile hole 7 is drilled to a predetermined depth, the tip bit 1
4 is kept in contact with the bottom of the hole, and the bottom expansion method bit is rotated in the opposite direction.

This rotation is the non-digging direction of the tip bit 14.

Conversely, this is the digging direction of the downhill bit 18 (FIG. 4).

Therefore, the fluid jacks 20 and 20 are extended downward at a speed and thrust according to the excavation capacity of the downhill bit 18, and turning is performed using the downhill bit 18.

At this time, the tip bit 14 remains in its original position without digging.

On the other hand, the sliding bit 18 digs downward at an angle equal to the inclination of the bottom-expanding guide 15 (FIG. 5B).

When the lower end of the downhill guide 15 is reached, the enlarged bottom part 9
The formation of is completed.

In addition, each cutter 18 of the sliding bit 18 and the tip bit 14
a, 14a are provided in the same direction, the direction of rotation of the downhill bit 18 during the excavation work is the same as the rotation direction of the tip bit 14, and the direction of rotation of the tip bit 14 is the same as that of the tip bit 14.
4 also rotates in the same direction, but at this time the tip bit 14
It is sufficient to suspend the pile hole from above via a drive pipe and support it so that its thrust does not apply to the bottom of the pile hole, thereby preventing the tip bit 14 from digging.

(■) Excavation with the downhill bit 18 and formation of the stabilizing film 29.

FIG. 6 shows an enlarged view of the state of excavation by the downhill bit 18.

That is, the sliding bit 18 excavates a portion corresponding to the base diameter of the pile hole T and the enlarged bottom portion 9 by turning the substantially horizontal turning surface 28 downward.

Therefore, the downhill bit 18 will never destroy the stabilizing film 29 formed on the hole wall surface of the previously dug pile hole 7 and the inner wall surface of the already excavated expanded bottom section 9, and therefore No collapse will occur.

Of course, there is no fear that the substantially horizontal turning surface 28 will collapse.

Therefore, the tapered expanded bottom portion 9 given by the expanded bottom guide 15 can be properly and reliably formed. 1 (■) Excavation of various holes FIG. 9, the hydraulic jack 20 is retracted in the same position to position the sliding bit 18 at the upper end of the bottom expansion guide 15, and then rotated in the excavation direction of the bottom expansion method bit 14 to remove a pile of a certain length l. Dig the hole 7 and make an enlarged bottom part 9 at the lower end of the hole 7.
The case is shown in which the same steps are repeated thereafter to form enlarged bottom portions 9 at fixed depths.

In addition, FIG. 7B shows a sliding bit 18 in the middle part of the pile hole 7.
This figure shows the case where the large-diameter portion 9' is formed by digging while the hole remains at the lower end of the bottom-expanding guide.

Furthermore, in FIG. 7C, when forming the expanded bottom portions 9 at every fixed depth of the pile hole 7 as shown in FIG. The case is shown in which the enlarged bottom portion 9 is formed by digging to a depth 1 and having a large diameter portion 9'.

In the above description, the excavation order was explained when the cutters 18a and 14a of the tip bit 14 and the downhill bit 18 were installed in opposite directions. When the pile hole 7 is being excavated, the large descending portion 9' can be excavated at the same time as the pile hole 7 by sliding down the sliding bit 18 as appropriate during the excavation of the pile hole 7.

Therefore, in this case, it is not necessary to perform the double work of digging the pile hole 7, pulling up the tip bit 14, inserting it into the pile hole again, and drilling the large diameter portion 9' later.

The sliding type bottom-expanding method bit according to the present invention is constructed, used, and functions as described above, and the present invention has the following effects.

First, since the sliding bit 18 moves along the inclination of the bottom-expanding guide 15 and digs downward into the substantially horizontal turning surface 28, the stabilizing film 29 is not destroyed except for the turning surface 28.

Therefore, the expanded bottom portion 9 does not collapse, and the expanded bottom portion 9 can be reliably formed as specified.

Second, the downhill movement of the downhill bit 18 can be remotely controlled through the control of a jack.

Therefore, it is possible to quickly excavate various types of pile holes or expanded bottom portions without having to raise the bottom expansion method bit to the ground each time.

[Brief explanation of drawings]

Figures 1A and B are side views showing a conventional expansion method bit, Figures 2A, B, and C are process diagrams showing an expansion pile hole drilling method using a conventional expansion method bit, and Figure 3 is a diagram according to the present invention. Side view of the sliding bottom expansion bit, Figure 4 is the bottom view of the same, Figure 5A
, B, and C are process diagrams of the method for drilling an expanded bottom pile hole using the expanded bottom method bit according to the present invention, FIG. 6 is an enlarged view showing the turning state of the expanded bottom part, and FIG. It is a sectional view of the hole showing the hole pile excavation method showing the construction method. 11... Drill shaft, 14... Tip bit, 15... Bottom expansion guide, 18... Downhill bit, 20... Jack, 14a ...,
18a...Katsuta.

Claims (1)

[Claims] 1. Attach a tip bit to the lower end of a drill shaft that is rotationally driven by a drive pipe, and in order to form an enlarged hole at the lower end of the pile hole, attach a bottom-expanding guide that is inclined so that the bottom expands along the taper of the hole. A sliding bit is fixed to the base plate, supported by the expanded bottom guide, and slidable along the guide in the vertical direction in the same posture, and has a downward hook, and further includes a fluid jack pivotally supported on the drill shaft. A sliding type bottom-expanding construction bit characterized in that the tip of the piston rond is pivotally connected to the sliding bit, and the sliding bit maintains the same posture and slides along the bottom-expanding guide as the piston rond extends.