JPH076177Y2 - Earth auger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an earth auger for ground improvement.

(Prior Art) Conventionally, as this type of earth auger, there is one described in JP-A-59-15118. This has a hollow drilling shaft with a drilling head attached to the tip, and a hollow stirring shaft fitted externally to this and having stirring blades on its outer peripheral surface. Both shafts are rotated while rotating them in opposite directions. And the soil is excavated by the excavation head, and when a predetermined depth is reached, both shafts are integrally elevated and the cement milk ejected from the tip of the hollow excavation shaft and the excavated soil are mixed by stirring. By doing so, a foundation pit is formed in the ground, and the ground is improved.

(Problems to be solved by the invention) According to the conventional earth auger, cement milk and excavated soil enter the gap between the hollow excavating shaft and the hollow agitating shaft due to earth pressure during excavation and agitation work, There is a drawback that the cement milk or the like that has infiltrated solidifies and prevents rotation of both shafts, so that stirring work cannot be performed in a predetermined manner.
Even if a seal material is interposed between both shafts in order to solve this drawback, the seal function is destroyed in a short period of time due to rotational friction and excessive earth pressure, and it is not practical.

The present invention has been made in view of the above conventional problems, and an object thereof is to provide an earth auger in which cement milk or the like does not enter the gap between the shafts.

(Means for Solving the Problems) In order to achieve the above object, the present invention has a hollow drilling shaft 6 having a drilling head 5 attached to its tip, and an agitating blade 7 fitted to the hollow drilling shaft 6 on the outer peripheral surface thereof. The hollow stirring shaft 8 and the hollow stirring shaft 8 are rotated in the forward and reverse directions independently of each other, but the shafts 6 and 8 are integrally lifted and arranged on the support leader 2, and a gap portion between the hollow excavation shaft 6 and the hollow stirring shaft 8 is provided. A pressure fluid supply port 28 for supplying a pressure fluid to 25 is provided in the auger body 4, and a metal bush 23 is interposed between the shafts 6 and 8 below the gap portion 25.

According to the second invention, the drive device 20 for rotating the hollow stirring shaft 8 is arranged below the support leader 2 on the support member 9 for preventing the shaking of the hollow stirring shaft.

(Operation) According to the present invention, the pressure fluid is supplied to the gap portion 25 between the hollow excavating shaft 6 and the hollow stirring shaft 8 which are rotated in the forward and reverse directions, and both shafts 6 are provided below the gap portion 25. Since the metal bush 23 is interposed between the gap 8 and the gap 8,
The pressure fluid supplied to is sealed in the gap portion 25 by the metal bush 23, or the lower portion of the gap portion 25 is narrowed by the metal bush 23 and is so-called squeezed to limit the discharge amount. The gap 25 is maintained at a high pressure by the pressure fluid, and during the excavation and stirring work, the gap 25
It is possible to effectively prevent the intrusion of cement milk and the like.

(Embodiment) FIG. 5 shows an earth auger according to an embodiment of the present invention, in which an auger body 4 is vertically movable on a guide rail 3 of a supporting leader 2 supported by a crane body 1.
A hollow drilling shaft 6 having a drilling head 5 attached to the tip thereof, and a hollow stirring shaft 8 externally fitted to the hollow drilling shaft 6 having stirring blades 7 mounted on the outer peripheral surface thereof.
And are vertically installed on the auger body 4, and the guide rail 3
A supporting member 9 for preventing steady movement of the shafts 6 and 8 is arranged in the lower part of the above so as to be able to move up and down.

As shown in FIG. 1, the hollow excavation shaft 6 is rotatably supported by the auger body 4 via a bearing 10, and is rotated by an electric or hydraulic excavation drive device 11 via transmission gears 12, 13. It can be operated (see FIG. 2). In addition, a cement milk supply pipe 6b is concentrically arranged in the torque tube portion 6a which constitutes the central portion of the excavation shaft 6.
The upper portion of the pipe 6b communicates with a cement milk supply port 15 provided on the upper portion of the auger body 4 through a swivel joint 14, and the lower portion thereof communicates with a cement milk discharge port 16 of the drill head 5, The cement milk supplied to the cement milk supply port 15 by the supply pump 17 is discharged from the discharge port 16 via the supply pipe 6b.

The hollow stirring shaft 8 is rotatably supported by the auger body 4 via a bearing 18, and is vertically inserted into a boss portion 19 provided on the support member 9 to raise and lower the auger body 4. By doing so, the hollow excavating shaft 6 can be moved up and down integrally. Further, as shown in FIG. 3, the outer peripheral surface of the hollow stirring shaft 8 and the inner peripheral surface of the boss portion 19 are formed in a polygonal shape and are fitted to each other, and an electric or hydraulic stirring drive device 20 is provided. Thus, the rotational force of the boss portion 19 rotated by the transmission gears 21 and 22 is transmitted to the hollow stirring shaft 8.

An annular metal bush (metal) 23 is fixed to the lower end portion of the inner peripheral surface of the hollow stirring shaft 8 as shown in FIG. 4, and the outer peripheral surface of the hollow excavating shaft 6 is coated with a ceramic so as to face the bush 23. A wear resistant coating 24 is formed by the above. Further, as shown in FIG. 1, the gap 25 between the hollow stirring shaft 8 and the hollow excavating shaft 6 has a communication hole 26, 26 formed in the torque tube portion 6a of the hollow excavating shaft 6 and the swivel joint 2
Pressure fluid supply port 2 provided under the auger body 4 via 7
The pressure fluid is supplied from the water pressure pump 29 or the air pump 30 to the gap portion 25 via the three-way switching valve 31. Below the gap 25, the annular metal bush 23 is fixed to the inner peripheral surface of the hollow stirring shaft 8 as described above, and the metal bush 23 comes into contact with the outer peripheral surface of the hollow excavating shaft 6 or a small amount. Therefore, the pressure fluid supplied to the gap 25 is enclosed in the gap 25 or so-called throttled to limit the discharge amount from the gap 25 to the outside. Are maintained at high pressure by the pressure fluid. For this reason, a gap 25 is formed between the bush 23 and the excavation shaft 6.
It is designed to prevent cement milk and the like from entering.

The agitation drive device 20 is disposed below the support leader 3 on a support member 9 provided on the guide rail 3 so as to be able to move up and down by a suspension rope (not shown), whereby the center of gravity of the support leader 3 is lowered and the earth is grounded. It improves the stability of the auger.

Explaining the procedure for soil improvement by the earth auger, the ground is excavated from the state shown in FIG. 5 while rotating both shafts 6 and 8 in opposite directions or by rotating only the excavation shaft 6 to a predetermined depth. When it reaches, the both shafts 6 and 8 are raised, the rotational speeds of the shafts 6 and 8 are switched to high speed, and the raising and lowering of the shafts 6 and 8 are repeated several times, whereby cement milk and excavated soil Stir to mix evenly. During this time, the pressurized fluid is supplied into the gap 25 at a pressure slightly higher than the earth pressure to prevent cement milk or the like from entering the gap 25.

According to the present invention, the pressure fluid is supplied to the gap between the hollow excavation shaft and the hollow stirring shaft, and the pressure fluid supplied to the gap is provided below the gap. Since the metal bush is filled in the gap or the amount of discharge from the gap to the outside is limited, the gap is constantly maintained at a high pressure by the pressure fluid, and therefore the cement to the gap is maintained. Since the invasion of milk or the like is effectively prevented, the problem that the rotation of both shafts is obstructed by the cement milk that has invaded the gap and solidified as in the conventional example described at the beginning is solved. It is possible to efficiently and uniformly stir and mix the excavated soil and the cement milk without causing a so-called co-rotation phenomenon, by reciprocally rotating the shaft independently of each other in a predetermined manner.

Further, according to the embodiment of the present invention, since the heavy hollow stirring shaft driving device is arranged on the supporting member which also serves as a steady rest of the hollow stirring shaft, the center of gravity of the supporting leader is lowered and the stability of the earth auger is improved. Contribute to.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an earth auger which is an embodiment of the present invention, and FIG. 2 is a lateral sectional view of a main part taken along line II-II in FIG.
3 is a cross-sectional view of the main part taken along the line III-III of FIG. 1, FIG. 4 is an enlarged cross-sectional view taken along the line IV-IV of FIG. 1, and FIG. 5 is a side view of the earth auger. is there. 2 ... Support leader, 4 ... Auger body, 5 ... Drilling head, 6 ... Hollow drilling shaft, 7 ... Stirring blade, 8 ... Hollow stirring shaft, 9 ... Supporting member, 20 ... Stirring drive shaft , 25 …… Gap, 28 …… Pressure fluid supply port.

Claims (2)

[Scope of utility model registration request] 1. A hollow drilling shaft 6 having a drilling head 5 attached to its tip and a hollow stirring shaft 8 externally fitted to the hollow stirring shaft 8 having stirring blades 7 mounted on its outer peripheral surface are rotated independently of each other.
Both shafts 6 and 8 are arranged on the support leader 2 so as to move up and down integrally, and the auger body 4 is provided with a pressure fluid supply port 28 for supplying a pressure fluid to a gap 25 between the hollow excavation shaft 6 and the hollow stirring shaft 8. The earth auger which is provided in the above and has a metal bush 23 interposed between the both shafts 6 and 8 below the gap portion 25. 2. A drive device 20 for driving the hollow stirring shaft 8 to rotate.
The earth auger according to claim 1, wherein the earth auger is provided below the support leader 2 on a support member 9 for preventing the shaking of the hollow stirring shaft.