JPH0714422Y2 - Earth auger - Google Patents

Description

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

(Prior Art) Conventionally, there is an earth auger shown in FIG. This is because the auger body 3 is arranged so as to be vertically movable on a support leader 2 supported by the crane body 1, and the auger body 3 is
A hollow drilling shaft 5 with a drilling head 4 attached to its tip
And a hollow stirring shaft 7 externally fitted to the excavation shaft 5 and provided with stirring blades 6 on the outer peripheral surface thereof so as to be independently rotatable and drivable, and between the lower ends of the shafts 5 and 7. A bearing 8 also serving as a sealing material is provided, and while rotating both shafts 5 and 7 in mutually opposite directions, the shafts 5 and 7 are integrally lowered, and the ground is excavated by the excavation head 4. When a predetermined depth is reached, both shafts 5 and 7 are integrally lifted to mix the cement milk and the excavated soil ejected from the cement milk outlet 9 of the excavation head 4 with the excavation head 4. The blades 6 are agitated and mixed to form foundation piles or the like in the ground.

(Problems to be Solved by the Invention) In the above-mentioned conventional earth auger, an excessive earth pressure is applied to the bearing 8, so that the sealing function thereof is easily broken in a relatively short time. Cement milk and excavated soil enter the gap 10 between the shaft and the agitator shaft 7, which solidifies and prevents the rotation of the shafts 5 and 7 and allows excavation and stirring work in a predetermined manner. There was a drawback that it would not be possible.

The present invention has been made in view of the above-mentioned conventional drawbacks, and an object thereof is to provide an earth auger capable of removing cement milk or the like from a gap between the shafts.

(Means for Solving the Problems) The structure of the present invention for achieving the above object will be described with reference to FIGS. 1 and 2 corresponding to the embodiment. Hollow drilling shaft 5
And an auger machine that is rotatably provided with a hollow stirring shaft 7 that is fitted onto the excavation shaft 5 and has stirring blades 6 attached to the outer peripheral surface thereof. 5 is supported by the inner wall of the hollow stirring shaft 7, and a spiral fin is screwed in the reverse screw direction with respect to the excavation rotation direction A of the excavation shaft 5 so that a feeding spiral mechanism is formed.
12 is projected.

(Operation) In the above configuration, when excavating the ground by the excavation head 4 provided on the excavation shaft 5, the screw-shaped fins 12 projecting from the excavation shaft 5 are brought into sliding contact with the inner wall of the stirring shaft 7, and the excavation shaft 5 is the stirring shaft. 7, the smooth rotation is maintained without being eccentric, and the screw fin 12 constitutes a feeding spiral mechanism, so that the excavating head 4 and the stirring blade 6 provided on the stirring shaft 7 allow cement milk and excavation. Even if cement milk or soil intrudes into the gap 11 between the shafts 5 and 7 due to earth pressure during the work of mixing with soil by stirring, the infiltrated cement milk or the like forms a spiral shape that forms a feeding spiral mechanism. The action of the fins 12 pushes it out of the gap 11 so that cement milk and the like hardly stay between the shafts 5 and 7, and the shafts 5 and 7 are always smoothly rotated.

(Embodiment) FIG. 1 shows an embodiment of the present invention. The same components as those of the conventional example shown in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. First, the hollow stirring shaft 7 is composed of a small-diameter cylindrical portion 7a on the upper side and a large-diameter cylindrical portion 7b integrally fixed to the lower end of the small-diameter cylindrical portion 7a.
In the gap 11 formed between the hollow excavation shaft 5 and the hollow excavation shaft 5, a screw-shaped fin 12 screwed in a reverse screw direction with respect to the excavation rotation direction of the hollow excavation shaft 5 projects on the outer periphery of the lower part of the same excavation shaft 5. The hollow digging shaft 5 is supported concentrically over the wide range α on the lower inner wall of the hollow stirring shaft 7 by being provided and slidingly contacting the inner wall of the stirring shaft 7, and the hollow digging shaft 5 rotates well without rattling. Driven. Also, during this rotation drive, the spiral fin
12 will actuate the payout helix mechanism that produces the downward thrust.

That is, the screw fin 12 is formed in a reverse screw direction with respect to the excavation rotation direction A of the excavation shaft 5 as shown in the second, and the excavation shaft 12 is formed at the time of ground excavation and stirring and mixing of cement milk and soil. By rotating 5 in the excavation rotation direction A, the feeding spiral mechanism composed of the above-mentioned screw-like fins 12 operates like a screw conveyer, and pushes excavated soil 13 entering the gap 11 out of the gap 11. You can

In FIG. 1, 14 and 15 are an electric or hydraulic excavation drive device and an agitation drive device, and are transmission gears 16, 17, 1 respectively.
The excavation shaft 5 and the stirring shaft 7 are rotated independently of each other via 8,19. Reference numeral 20 is a cement milk supply pump, which is provided with a swivel joint 21 provided on the upper part of the auger body 3 and a cement milk supply hole 22 penetrating the center of the excavation shaft 5 to allow the cement milk discharge port 9 of the excavation head 4 to pass therethrough. The cement milk is spouted from.

(Effect of the Invention) According to the present invention, since the spiral fins are provided on the outer periphery of the hollow excavating shaft, the excavating shaft and the hollow stirring shaft fitted onto the excavating shaft are always supported concentrically. The cement milk and excavated soil that enter the gap between the shafts are forced out of the gap by the principle of the screw conveyor. Therefore, as in the conventional example described at the beginning, there is no fear that the cement milk or the like that enters the gap solidifies and inhibits the rotation of both shafts, and the both shafts are driven to rotate smoothly in a predetermined manner, Excavation work can be performed efficiently.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an earth auger as an embodiment of the present invention, FIG. 2 is an enlarged vertical cross-sectional view of the essential part, and FIG. 3 is a side view showing a conventional example. 4 ... Drilling head, 5 ... Drilling shaft, 6 ... Stirring blade, 7
…… Agitation shaft, 12 …… Spiral fin.

Claims (1)

[Scope of utility model registration request] 1. An auger machine comprising a hollow drilling shaft having a drilling head attached to its tip, and a hollow stirring shaft externally fitted to the drilling shaft and having stirring blades mounted on its outer peripheral surface so as to be rotatable. At the outer periphery of the excavation shaft, the excavation shaft is screwed in the reverse screw direction with respect to the excavation rotation direction of the excavation shaft so that the excavation shaft is supported by the inner wall of the hollow agitation shaft and a feeding spiral mechanism is configured. Earth auger characterized by protruding screw fins.