JPS636314Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention relates to an excavation bit used in the construction of the medium excavation bottom expansion method using hollow piles. This invention relates to a drilling bit that can be used for switching between normal drilling and bottom-expanding drilling by dynamically displacing the bit.

In the past, various types of excavation bits have been developed and used for the construction of the medium excavation method, but most of them are for the reverse circulation method, and none that can be applied to earth augers have been found.

Therefore, the purpose of this invention was to create a medium-deep drilling method that can be attached to the tip of an auger screw and can be used to switch between normal drilling and bottom-expanding excavation by rotating and displacing the rotor blades. Our goal is to provide drilling bits.

In order to achieve the above object, the excavation bit for medium excavation and bottom expansion method of this invention has a tip blade attached downward to the lower end of a vertically elongated, substantially rectangular flat frame, and rotary blades are installed on both sides of the frame. The rotary blade is attached so as to be rotatable in the vertical direction, and a digging blade is attached along the lower edge of the rotor blade. On the other hand, the frame is provided with at least two types of stoppers that press the upper edge of the rotor blade or a similar portion thereof at predetermined rotational angle positions of the rotor blade, and the lower stopper moves in and out according to the rotational displacement of the rotor blade. I am free to do so. Further, the frame is provided with a concrete injection pipe and an injection valve connected to the pipe, and is configured to be attached to the tip of the auger screw.

In other words, if drilling is carried out with the rotor blades fixed in an obliquely upwardly tilted state, it is possible to drill a small-diameter normal hole.

Next, by rotationally displacing and fixing the rotor blade to a substantially horizontal position using a hollow pile or the like, a large diameter enlarged bottom portion can be excavated.

Thereafter, by rotating the rotor so that it hangs downward substantially vertically, it can be lifted to the ground through the hollow pile. At the same time, during the raising, concrete can be injected through the pipe and injection valve to form an expanded pile foundation.

This excavation bit has an extremely simple structure, can be manufactured and used at low cost, and can be applied to an earth auger for use in the medium excavation and bottom expansion method.

Next, the illustrated embodiment will be explained.

FIG. 1 shows a front view of the drilling bit. 1 in the diagram
It is a long rectangular plate-shaped frame with dimensions of approximately 650 x 280 x 60 mm in length, width, and thickness. The lower end of the frame 1 is formed into a triangular shape with an apex angle of about 120°, and tip blades 2 are attached downward.

In the figure, reference numerals 3 and 3 denote a pair of rotary blades that are attached to both side surfaces of the frame 1 at the substantially central portion thereof with bolts 4 so as to be rotatable in the vertical direction. The rotary blade 3 has a flat plate shape and has a length of about 280 mm from the bolt 4 to the tip.

As shown in FIG. 2, a presser guide 5 having an L-shaped cross section is fixed to the base end of each rotor blade 3.
A digging blade 6 is attached to each rotor blade 3 along its lower edge.

Therefore, when the rotor blade 3 rotates, it exerts downward digging ability.

In the figure, 7 and 8 are two types of stoppers provided on both sides of the frame 1. Stoppers 7 and 8 are bolts 4
The upper edge of the rotor blade 3, which rotates around the rotor blade 3, is held down with a force greater than the excavation resistance to enable excavation. There is. That is, the upper stopper 7
is provided as a block-shaped steel member fixed by welding or the like so as to engage with the upper edge of the rotor blade 3 at a position rotated approximately 30 degrees upward from the horizontal. On the other hand, the lower stopper 8 engages with the upper edge of the rotary blade 3 when it rotates from a rotational position upward from the horizontal to a substantially horizontal position, and prevents the rotor from rotating upward. So this stopper 8
is set up so that you can come and go as you like.

That is, as shown in the cross-sectional view in FIG. The other end of the coil spring 11 is brought into contact with the rear end surface of the stopper 8, and a pressing force in the forward direction is constantly applied. In the figure, 8a is a notch-shaped engagement portion provided at the lower front end of the stopper 8, and 8b
is a tapered surface that engages with the lower edge of the rotary blade 3 and is pushed by the lower edge to cause the stopper 8 to retreat against the coil spring 11. Note that the lower side edge of the rotary blade 3 may be tapered, and the tapered surface 8b of the stopper 8 may be omitted. Reference numeral 12 denotes a protrusion prevention piece that defines the forward position of the stopper 8.

In other words, when the upper edge of the rotor blade 3 is held down by the upper stopper 7, the lower stopper 8 is pushed into the hole 9 by the rotor blade 3, and in this state, the hole of approximately φ520 is cut. A hole is made. However, when the rotary blade 3 is rotated slightly downward from the horizontal position, the lower stopper 8 protrudes.
Since the upper edge of the rotary blade 3 is held down to prevent it from rotating upward from the horizontal position, it is possible to excavate an enlarged bottom portion of about φ600.

Note that if the rotary blade 3 is rotated further downward, it will fit within the width dimension of the frame 1, and it will be possible to raise it to the ground.

13 in the figure is a concrete injection pipe,
It is attached along one side of the frame 1. One end of the injection pipe 13 is connected to an inlet nozzle 14 at the upper end of the frame 1, and the other end is connected to a concrete injection valve 15 protruding from one side of the lower part of the frame 1.

The details of the injection valve 15 are shown in cross section in FIG. 4, by fixing the base 15a to the frame 1 by welding,
A cylindrical valve box 15b is attached to this with screws 15c, a bearing 15d with a concrete flow structure is provided at the opening at the tip of the valve box 15b, and the valve shaft 15f of the valve body 15e is slidably supported by the bearing 15d. , a closing spring 15g is wound around the valve shaft 15f. The injection pipe 13 and valve box 15b
and are connected by 15h.

That is, this injection valve 15 is closed by the closing spring 15g. Only when air or concrete is injected through the injection pipe 13, the valve body 15e is pushed open by pressure from inside, and concrete can be poured into the valve body 15e. That is,
It functions as a so-called check valve.

FIGS. 5A to 5D show the construction sequence of the medium excavation bottom expansion method using the above-mentioned excavation bit.

That is, the drilling bit is attached to the tip of the auger screw 16 of the earth auger, and serves as a so-called leading blade for digging a hole sufficient to bury the hollow PC pile 17. That is, as shown in FIG. 5A, the rotor blade 3 is fixed in an upward angular position held by the upper stopper 7, and is inserted into a normal small diameter hole (φ520).
Used for drilling holes.

However, when reaching the vicinity of the supporting layer ground and excavating the bottom expansion part, first the auger screw 1
6, once pull up the frame 1 of the drilling bit slightly upwards. Then, since the rotor blade 3 is locked to the lower end of the stationary hollow PC pile 17, its lower edge hits the tapered surface 8b of the stopper 8, and while the stopper 8 is retreated against the coil spring 11 (the third Figure) It is rotated relatively downward. Next, when the load is applied again to the frame 1 of the drilling bit through the auger screw 16 and digging is started,
A force is also applied to the rotor blade 3 to rotate it upward about the bolt 4, but the lower stopper 8 locks the upper edge of the rotor blade 3 (FIG. 3), and the rotor blade 3
is held fixed in a substantially horizontal position. Therefore, it becomes possible to excavate the enlarged bottom portion 18 with a large diameter (φ600) as shown in FIGS. 5B, C, and D.

Thus, when the entire excavation process is completed, the auger screw 16 is slowly pulled up. Then, the rotor blade 3 of the drilling bit is locked to the lower end of the hollow PC pile 17 and further rotated downward.
As a result, as shown in FIG. 5D, the rotor blade 3 hangs downward in a folded form smaller than the inner diameter of the hollow part of the hollow PC pile 17. Therefore, the drilling bit can be pulled up inside the hollow PC pile 17 without any trouble.

In addition, when pulling up the excavation bit, concrete is injected and filled through the injection pipe 13 and the injection valve 15 to complete the root hardening of the bottom expansion pile.

Next, Fig. 6 shows a steel pipe 19 instead of a hollow PC pile.
The construction drawings of the medium excavation and bottom expansion method are shown below. Note that a feature is that a collar 20 is provided at the lower end of the steel pipe 19 in order to ensure that the rotor blade 3 comes into contact with it.

[Brief explanation of drawings]

FIG. 1 is a front view of a drilling bit according to the present invention;
Figures 2, 3, and 4 are - and - of Figure 1.
, - arrow sectional view, FIGS. 5A, B, C, and D, and FIG. 6 are construction drawings of the medium excavation bottom widening method using the above-mentioned excavation bit.

Claims (1)

[Scope of utility model registration request] A tip blade 2 is attached downward to the lower end of a flat frame 1, and rotary blades 3 are attached to both sides of the frame 1 so as to be rotatable in the vertical direction. The frame 1 is provided with at least two types of stoppers 7 and 8 at predetermined rotation angle positions of the rotor blade 3 for pressing the upper edge of the rotor blade 3, and the lower stopper 8 is When the rotor blade 3 moves downward, it is pushed back by the side surface of the rotor blade 3 so that it can retract and retract freely, and the frame 1 is provided with a pipe 13 for pouring concrete and an injection valve 15 connected to the pipe 13. An excavation bit for a medium excavation bottom expansion method, characterized in that it is used by being attached to the tip of an auger screw 16.