JPH0144596Y2 - - Google Patents

Description

[Detailed description of the invention] Casing pipes used in the all-casing method, which is one of the foundation pile driving methods, and piles used to cut friction between the piles and earth and sand when pulling out existing piles. This invention relates to a mounting structure for a digging blade that is attached to the tip of a casing pipe with a diameter larger than the diameter of the pipe.

There is a so-called all-casing construction method in which the foundation pile is constructed by pushing the casing pipe through the entire length of the foundation pile by swinging or rotating while removing the earth and sand inside the casing pipe using a bucket or the like. Conventionally, in order to reduce the pushing resistance of this casing pipe, the cutting edge at the tip was made into an acute angle shape, and the cutting diameter was made larger than the diameter of the upper body to avoid direct contact between the body and the ground, and the circumferential surface during pushing Some have reduced frictional resistance, some have carbide chips embedded in the tip of the casing pipe, and others have digging blades attached. Among these, the one with the digging blade attached has the lowest pushing resistance, but as shown in FIG. 6, the conventional mounting structure of the digging blade 200 is
Since they are installed in a row under the cutting edge of the 0, there is insufficient consideration for the discharge of excavated soil, and the pushing resistance cannot be said to have been sufficiently reduced.

The present invention relates to an improvement of the mounting structure of the excavating blade, and allows the earth and sand excavated by the excavating blade to be quickly discharged and to reduce the pushing resistance. The purpose of this invention is to provide a structure for attaching a digging blade to the tip of a casing pipe.

In order to achieve this objective, the present invention provides a device that excavates the ground by attaching a digging blade to the tip of a casing pipe and rotating the casing pipe to reduce the pushing resistance of the casing pipe. The cutting blades are arranged alternately on the inner circumferential side and the outer circumferential side of the pipe, and are characterized in that they are configured to create a gap between the excavating blades and the inside of the body and the outer wall of the casing pipe.

Hereinafter, one embodiment of the present invention will be described in more detail with reference to FIGS. 1 to 5. FIG. 1 is an overall side view showing a rotary pushing device to which the present invention is applied, and FIGS. 2 to 5 are enlarged detailed views of the excavator blade mounting structure of the present invention. 2 is a frame installed on the ground, 3 is a band for tightening the casing pipe 1, and a tightening force is applied by a tightening cylinder 4. Reference numeral 5 denotes a geared turning ring, the outer race of which is provided with a gear, and further connected to a fixed portion of the band 3. A pinion 6 meshes with the geared turning wheel 5 and is rotationally driven by a motor 7. 8 is a bracket for fixing the motor 7, and is fixed to the frame 9. An inner race of the geared turning wheel 5 is fixed to the frame 9. 1
0 is a pushing cylinder provided between the frame 9 and the pedestal 2. Note that 11 indicates a hammer grab for discharging the earth and sand in the casing pipe 1 to the ground.

As shown in FIGS. 3 and 5, the tip of the casing pipe 1 has a ring-shaped step with dimensions equal to or slightly smaller than the gap δ ₁ from the body 1a, and also has an inclined portion 1b. are doing. A digging blade 12 disposed on the inner circumferential side and a digging blade 13 disposed on the outer circumferential side are alternately attached to the tip end via bolts 14. The excavating blade 12 is formed with a flank 12a that creates a gap δ ₂ between its inner end and the inner wall of the body portion 1a. Further, the excavating blade 13 is formed with a flank 13a that creates a gap _δ1 between its outer end and the outer wall of the body portion 1a. In addition, a carbide chip 1 is placed on the rake surface of the excavating blade 12.
2' is attached in a mountain shape, and the relief angle β ₁ is at the bottom.
A relief angle β ₂ is formed on the side surface. Similarly, a carbide tip 13' is attached to the rake face of the excavating blade 13 in the shape of a mountain, with a clearance angle β ₁ formed at the lower part and a clearance angle β ₂ formed at the side surface.

Next, the operation of the present invention will be explained. The casing pipe 1 is integrated with the band 3 by contracting the tightening cylinder 4. When the motor 7 is driven in this state, the geared turning wheel 5 is rotated by the pinion 6, and the band 3, which is partially fixed integrally with the geared turning wheel 5, is also rotated. Pipe 1 is also turned. By contracting the pushing cylinder 10 while rotating in this manner, a pushing force is applied to the casing pipe 1.

On the other hand, at the cutting edge portion of the casing pipe 1, pushing force and rotational force are applied to the excavating blades 12 and 13, so that the ground is excavated. As a result of the excavation by the excavation blade 12, a gap of δ ₂ is created on the inner circumferential side of the casing pipe 1, and the dirt and sand that goes around behind the excavation blade 12 through the gap created by this gap. is pushed upward. Further, as a result of excavation by the excavating blade 13, a gap of δ ₁ is generated on the outer circumferential side of the casing pipe 1, and the excavating blade 1 passes through the gap created by this gap.
The rest of the earth and sand that goes around to the rear of the casing pipe 3 is pushed upward, guided by the inclined part 1b that opens the end face of the casing pipe 1 toward the inner circumference, and is pushed out toward the inner circumference of the casing pipe 1. Further, the earth and sand excavated by the excavation blade 13 also serves to push out loose earth and sand that has wrapped around behind the excavation blade 12 toward the inner circumferential side. In addition, most of the ground on the inner circumferential side of the excavation blade 13 has already been excavated by the excavation blade 12, and even if there is not a complete void, the loosened earth and sand by the excavation blade 12 is removed by the excavation blade 13. In order to provide a place for escape, compared to a digging blade in which the digging blade 12 and the digging blade 13 are integrated, that is, a structure in which the entire cross section is excavated at once,
The excavation resistance, which is the sum of the excavation resistance of the excavation blade 12 and the excavation blade 13, is smaller. The same applies to the relationship in which the excavating blade 13 is in the lead and the excavating blade 12 is in the trailing position. Therefore, the earth and sand excavated by the excavating blades 12 and 13 are stirred and fluidized, so that they can be easily discharged. Since the excavated earth and sand are discharged smoothly in this way, the pushing resistance of the casing pipe can be kept small.

Incidentally, the excavating blades 12 and 13 are provided with relief angles β ₁ and β ₂ so that surfaces other than the rake surface are unlikely to come into contact with the ground, so it is possible to prevent an increase in rotational resistance due to contact with the ground. can.

As described above, according to the present invention, the excavation blades that excavate the ground under the cutting edge of the casing pipe are divided into the inner circumferential side and the outer circumferential side and are installed alternately. It is easy for the earth and sand to go around the cavity, and the movement of the excavated earth and sand is carried out smoothly. Furthermore, the earth and sand excavated by the outer peripheral side digging blade is loosened and is located behind the inner peripheral side digging blade. In addition to being able to push out the excavated earth and sand to the inner circumferential side, by forming a gap on the inner circumferential side, the earth and sand can be smoothly pushed upward along the inner wall of the casing pipe and discharged. The mounting structure of the excavator blade takes into account the discharge of water and the reduction of excavation resistance, which has the effect of reducing the pushing resistance of the casing pipe.

[Brief explanation of the drawing]

Fig. 1 is an overall view of a rotary pushing device to which the present invention is applied, Figs. 2 to 5 show an embodiment of the present invention, and Fig. 2 is an enlarged detailed view of section A in Fig. 1. ,
Fig. 3 is a partially cross-sectional view taken along the - line in Fig. 2, Fig. 4 is a sectional view taken along the - line in Fig. 2, and Fig. 5 is a sectional view taken along the - line in Fig. 2. FIG. 6 is a partially sectional perspective view of a conventional excavator blade attachment structure provided at the tip of a casing pipe. 1...Casing pipe, 1a...Body part, 1
2, 13...Drilling blade, 12a, 13a...Flank surface, 14...Bolt, _δ1 , _δ2 ...Gap.

Claims (1)

[Scope of utility model registration request] In a device that excavates the ground by attaching a digging blade to the tip of a casing pipe and rotating the casing pipe to reduce the pushing resistance of the casing pipe, the digging blade is alternately placed on the inner circumference side and the outer circumference side of the casing pipe. A casing pipe tip excavator blade mounting structure characterized in that the excavator blades are arranged at the tip of the casing pipe and are configured to create a gap between the excavator blades and the inner and outer walls of the body of the casing pipe.