JPH0415826Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention is a removable excavator blade that is attached to a casing bit with a ground excavation cutter used in the all-casing method, which is one of the foundation pile driving methods. It's about structure.

[Conventional technology]

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 efficiently excavate hard soil or rock, there are casing bits in which a carbide chip is embedded in the tip of the lowest casing pipe or the excavation blade is fixed by welding.

[The problem that the idea aims to solve]

However, with this method, if the excavation blade becomes worn or broken, the welded part must be removed by fusing each time, and if many pieces are replaced, the work time increases, and the next foundation pile is replaced. In order to hinder construction, it was necessary to prepare at least two sets of casing bits with co-excavation blades, which was a factor in increasing costs.

Also, depending on the construction site, the ground may be hard soil, a layer of rolled stones, bedrock, or reinforced concrete for urban redevelopment.
Therefore, in order to perform these excavations efficiently, it is necessary to select the hardness, toughness, and shape of the cemented carbide to be attached to the excavation blade, as well as the rake angle and relief angle of the excavation blade, and the number of installed excavation blades. It is necessary to change, but
Since the excavation blade is attached by welding, there are problems in that it takes time to replace it and it is necessary to prepare a number of casing bits to suit each ground. In some cases, all the ground was excavated with one bit, resulting in a decrease in excavation efficiency.

Although it was not disclosed as a casing bit for the all-casing construction method, it was used as a cutter head for earth auger drills in 1987-115702.
A removable digging blade is disclosed in the publication. This has a digging blade removably fastened to the tip of a spiral wing piece with a bolt. In the case of an earth auger, the drilling diameter is usually around φ400 to φ800, and if the cutting blade is attached to such a small diameter, the rotation radius is small, so the cutting force is always applied diagonally in front of the cutting blade, and the cutting blade is forced to move laterally. Receive power. These problems were solved by providing a complicated notch shape in order to prevent lateral displacement caused by this and to prevent load from being applied to the fastening bolt. For this reason, the tip of the helical blade also has an uneven notch rather than a straight line, resulting in a decrease in strength due to stress concentration. Furthermore, because it is not possible to embed the blade into the plate thickness of the spiral blade due to side slip prevention and axial load considerations, there is a problem in that both the front and back sides of the excavation blade are easily worn out by excavated soil, requiring early replacement. Ta.

The present invention improves the problems of the conventional technology as described above, and provides a casing for the all-casing construction method that can be used immediately in the event of breakage or wear, or when it is necessary to replace the excavation blade depending on the object to be excavated. The purpose of this invention is to provide a removable excavation blade for bits.

[Means to solve the problem]

In order to achieve the above-mentioned purpose, the present invention has been developed to enable bolt fastening in the thickness direction of the casing pipe in a drilling blade that has a carbide tip that is removably attached to the cutting edge of the casing pipe with a bolt. It is characterized in that it has a fork-shaped shank portion made up of two plates, and has no irregularities other than bolt fastening holes on opposing surfaces of the two plates.

[Effect]

As mentioned above, in this invention, the digging blade can be fastened to the tip of the casing pipe with a bolt, so if the digging blade becomes damaged and needs to be replaced, it can be easily and easily replaced. It can be easily replaced, and since the casing pipe or the excavation blade is shaped like a fork and the cylindrical part is formed continuously up to the tip of the casing pipe, the excavation blade can be attached and removed using bolts. Even though it can be fastened freely, a large decrease in strength can be prevented.

〔Example〕

Hereinafter, one embodiment of the present invention will be specifically described using FIGS. 1 to 6. FIG. 1 is an overall side view showing a rotary pushing device to which the present invention is applied, and FIGS. 2 to 6 are enlarged detailed views of the removable excavator blade mounting structure of the casing bit of the present invention. 2 is a frame installed on the ground; 3 is a band for tightening the casing pipe 1 having the casing bit 1a;
The tightening force is applied by the 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 that is equal to or slightly smaller than the gap δ ₁ from the body 1b, and has a ring-shaped step on the inner peripheral side. Slope part 1 opened to
It has c. A cylindrical plate 1d, which has a thinner wall thickness than the casing pipe 1, is formed at the tip of the blade.
d has a hole 1d'. For this reason, the casing pipe 1 is not cut in the wall thickness direction, but the cylindrical portion of the casing pipe 1 is formed up to the cutting edge, and consideration is given to strength. Drilling blade 1 so as to sandwich the plate 1d.
A fork-shaped shank 12b, 13b consisting of two plates 2 and 13 is fitted in and fastened with a bolt 14 and a nut 15. 2 mentioned above
The facing surfaces of the two plates are flat with no irregularities such as notches other than bolt holes. At this time, the gap between the forks of the shank 12b, 13b is configured to be approximately 1 to 2 mm larger than the plate 1d, and when fastened with the bolt 14 and nut 15, the shank 12b, 13b exhibits a spring effect, To prevent the bolt 14 from loosening. Further, both the bolt 14 and the nut 15 are configured to be embedded in the shank. In addition, shank 12b, 1
3b is inserted into a rectangular groove of the casing pipe 1, and the load applied to the tip of the excavation blade during excavation is supported by this groove, so that no load is applied to the bolt 14. Here, an example has been described in which the bolt 14 and nut 15 are fastened together, but it goes without saying that a screw hole may be made on the shank side and also serve as a nut. The digging blade 12 has an inner end and a body 1.
b Relief surface 1 that creates a gap δ ₂ with the inner wall
2a is formed. 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 1b. Further, a carbide tip 12' is attached in a mountain shape to the rake face of the excavating blade 12, and a clearance angle β ₁ is formed at the lower part and a clearance angle β ₂ is formed at 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. Here, force acts on the tips of the digging blades 12 and 13 due to the pushing force and rotational force, and a reaction force due to a moment multiplied by the distance from the tip of the casing pipe 1 is applied to the bolt 14 or the shank 12b, 13b. It acts on the groove of the casing pipe 1 which is in contact with. At this time, since the shank 12b and 13b are contained within the thickness of the casing pipe, they come into contact with the side surfaces of the two plates that make up the shank, making effective use of the entire plate thickness. Can support reaction forces. Here, it is preferable to provide a gap between the bolt 14 and the hole drilled in the casing pipe 1 so that no reaction force acts on the bolt 14. Drilling blade 12,1
Since the shank 12b and 13b of No. 3 are fork-shaped, when they are inserted into the groove of the casing pipe 1 and fastened with the bolt 14 and nut 15, tension is applied to the bolt 14 due to the elasticity of the shank. It becomes difficult to loosen. If replacement is necessary due to damage etc., loosen nut 15 and remove bolt 14.
You can remove the excavator blade by removing it. Drilling blade 1
2 and 13 are divided into the inner circumference side and the outer circumference side of the casing pipe 1 to form an excavation groove larger than the thickness of the shank, so the ground is not directly excavated with the shank.

In addition, in FIGS. 2 and 3, the shank 12b, 13b of the drilling blades 12, 13 is directly attached to the casing pipe 1.
The example shown is to drill grooves and bolt holes, but considering machining problems and the possibility of the grooves becoming loose due to aging during actual use, these parts were created as blocks 16 and 17 as shown in Figure 6. A separately processed piece may be fixed to the casing pipe 1 by welding. Even in this case, the cylindrical shape of the casing pipe is maintained, and a large decrease in strength can be prevented. Further, as a result of excavation by the excavation blade 12, a gap of δ ₂ is created on the inner peripheral side of the casing pipe 1, and other than the earth and sand that go around behind the excavation blade 12 through the gap created by this gap, being pushed upwards. Furthermore, as a result of the excavation by the excavation blade 13, a gap of δ ₁ is created on the outer circumferential side of the casing pipe 1, and other than the earth and sand that wraps around behind the excavation blade 13 through the gap created by this gap, the upper part of the casing pipe 1 is The casing pipe 1 is pushed up toward the inner periphery of the casing pipe 1 by being guided by the inclined portion 1c that opens the end face of the casing pipe 1 toward the inner periphery. Further, the earth and sand excavated by the excavation blade 13 also serves to push out loose earth and sand that has wrapped around the rear of the excavation blade 12 toward the inner circumferential side. In addition, most of the ground has already been excavated by the excavating blade 12 on the inner circumferential side of the excavating blade 13, and even if there is not a complete void, the excavating blade 1
2, the soil excavated by the excavation blade 13 has a place to escape, so compared to an excavation blade in which the excavation blade 12 and the excavation blade 13 are integrated, that is, a structure in which the entire cross section is excavated at once. However, the excavation resistance, which is the sum of the excavation resistance of the excavation blade 12 and the excavation blade 13, is smaller. Drilling blade 13 takes precedence, and digging blade 1
The same applies to the relationship where 2 is the successor. 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 smoothly discharged in this way, the pushing resistance of the casing pipe can be kept small.

Note that clearance angles β ₁ and β ₂ are provided on the excavating blades 12 and 13 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.

[Effect of idea]

As mentioned above, in the present invention, the digging blade is removably attached to the tip of the casing pipe using bolts, so if the digging blade becomes damaged or needs to be replaced due to other reasons, it can be easily and easily replaced. can be exchanged for. In addition, in the present invention, the excavating blade is shaped like a fork, and the excavating blade is bolted in the thickness direction of the casing pipe, and the tip of the casing pipe forms a continuous cylindrical part. Even though it is made removable, a large decrease in strength can be prevented.

In addition, the present invention has a fork-shaped excavating blade and bolts the excavating blade in the thickness direction of the casing pipe, and since the shank has no irregularities other than the bolt fastening hole, the reaction force of the force acting on the excavating blade As a result, a detachable excavating blade for a casing bit for the all-casing construction method can be obtained, which has a simple structure, is inexpensive, and has little wear on the shank.

[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 diagram showing another embodiment in which the portion where the shank of the excavator blade is attached to the casing pipe is made into a block. 1...Casing pipe, 1a...Body part, 1
2, 13...Drilling blade, 12a, 13a...Flank surface, 12b, 13b...Shank portion, 14...Bolt, 15...Nut.

Claims (1)

[Scope of utility model registration request] A fork-shaped shank consisting of two plates that can be bolted together in the thickness direction of the casing pipe in a drilling blade that has a carbide tip that is removably attached to the tip of the casing pipe with a bolt. 1. A removable excavating blade for a casing bit for an all-casing construction method, characterized in that the opposing surfaces of the two plates have no irregularities other than bolt fastening holes.