JP3444836B2 - Auger screw - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auger screw used by being attached to an earth auger, and more particularly to an auger screw suitable for improving columnar consolidation of soft ground.

[0002]

2. Description of the Related Art As one of the methods for compacting soft ground,
A columnar consolidation method based on an earth auger for excavation is known. This method excavates the ground to the required depth with an earth auger, then sends the earth and sand added to the earth soil previously excavated by the reverse rotation of the earth auger to the bottom of the excavation hole for consolidation, The consolidation reaction force resists the load applied from the working machine side, and the earth auger gradually rises from the excavation hole to form a columnar consolidation foundation in the ground.

[0003]

However, in the above-mentioned construction method, the earth and sand are fed along the longitudinal direction of the earth auger by the reverse rotation of the earth auger, but in the vertical direction of the pressure due to the mounting angle of the spiral blade of the earth auger. Depending on the soil quality, the soil will not spread so much in the lateral direction (outward in the radial direction of the drill hole), and the soil will immediately compact in the vertical direction and a consolidation reaction force will be generated. It is difficult to create a columnar consolidated foundation with a sufficient spread.

Further, in the above-mentioned construction method, it is necessary to apply a sufficient load from the working machine side because the load against the consolidation reaction force that pushes up the earth auger causes a difference in the degree of consolidation. About 10 tons is required, which is a constraint when trying to develop a small machine according to the circumstances of a small residential area in an urban area.

The present invention has been made in consideration of the above circumstances, and provides an auger screw suitable for ground consolidation, which can easily form a columnar consolidation foundation having a sufficient strength and having a lateral expansion. The purpose is to

[0006]

[Means for Solving the Problems] Claim 1 of the present invention
The auger screw according to (1) is provided with a rod that is moved up and down and rotated by an auger machine, a main spiral blade that is provided on the outer periphery of the rod and that conveys earth and sand along the rod by the rotation of the rod, and a tip of the rod. In an auger screw having an auger head, the auger head has a substantially arc-shaped cross-section for excavating the ground by the forward rotation of the rod and pushing the earth and sand outward in the radial direction of the excavation hole by the reverse rotation of the rod to consolidate the soil. A compacting cam having a plurality of cam surfaces, and an auxiliary spiral blade continuous with the cam surface on the upper side of the compacting cam, the compacting cam having a basic circle having an outer diameter substantially the same as the outer diameter of the rod. However, one end of each cam surface on the reverse rotation side is in contact with this basic circle, and the part connecting the other end of the cam surface and the basic circle is the excavation part for excavating the ground, and the consolidation cam goes to the tip when viewed from the side. Ho None narrowed semicircular, characterized in that a predetermined gap is formed in the axial direction or the circumferential direction of the rod between the main helical blades and the auxiliary helical blades.

The auger screw according to a second aspect of the present invention is the auger screw according to the first aspect, wherein the auxiliary spiral blade is formed to have a smaller diameter than the main spiral blade.

An auger screw according to a third aspect of the present invention includes a rod which is vertically moved and rotated by an auger machine, a spiral blade which is provided on an outer periphery of the rod and conveys earth and sand along the rod by rotation of the rod, and a rod of the rod. In an auger screw provided with an auger head provided at the tip, the auger head excavates the ground by forward rotation of the rod and pushes earth and sand radially outward of the excavation hole by reverse rotation of the rod to consolidate. horizontal cross section arcuate compaction cam having a plurality of cam surfaces are provided, wherein the compaction cam has a generally base circle having the same outer diameter as the outer diameter of the rod, opposite the cam surface on the base circle One end on the rotating side is in contact, and the part connecting the other end of the cam surface and the base circle is the excavation part for excavating the ground.The consolidation cam has a semicircular shape that narrows toward the tip when viewed from the side, and the spiral Wings are in front Together provided only Article number corresponding to the number of the cam surfaces of the compaction cam, characterized in that each helical blade is continuous to the respective cam surfaces.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

1A and 1B are views showing an auger screw according to a first embodiment of the present invention. FIG. 1A is a side view of a lower portion of the auger screw, and FIG. 1B is a view of the auger head seen from another direction. FIG. 2 is a side view, (c) is a front view of the auger head as seen from below, and FIG. 2 is an enlarged side view of essential parts of the auger screw of FIG.

The auger screw 1 shown in the drawing has a rod 2 which is vertically moved and rotated by an auger machine (not shown). A main spiral wing 2A for transporting earth and sand along the rod 2 by the rotation of the rod 2 is provided on the outer periphery of the rod 2, and the auger head 3 can be attached to and detached from the tip of the rod 2 by a bolt 20. Is attached to. In the illustrated example, the main spiral blade 2A has one thread, but it may have a plurality of threads, for example, two threads.

A compacting cam 4 is provided at the tip of the auger head 3. The consolidation cam 4 excavates the ground by forward rotation of the rod 2 [rotation in the direction of arrow A in the figure (c) = clockwise rotation] and reverse rotation of the rod 2 [rotation in the direction of the arrow B in the figure (c) = counterclockwise rotation]. ], The two cam surfaces 5A for pressing and consolidating the earth and sand radially outward of the drill hole [direction of arrow F in Fig. (C)],
Have 5B.

[0013] Consolidation cam 4, the cam surface 5A consisting of lateral substantially arcuate cross section contour curve, the cam portion 6A, the rotation center C combined facing 6B lateral substantially semicircular section of the pair (two) having 5B On the other hand, it is formed in a cross-sectional shape that is eccentric by the same eccentric amount in opposite directions. Further, as shown in (c) of FIG. 1, the consolidation cam 4 has a basic circle Dx having an outer diameter substantially the same as the outer diameter of the rod 2, and the cam surfaces 5A, 5A, 5A on the basic circle Dx.
One end of B on the reverse rotation side (arrow B direction side ) is in contact. The portions connecting the other ends of the cam surfaces 5A, 5B and the base circle Dx are excavation portions 7A, 7B for excavating the ground. This excavation part 7
A and 7B are preferably formed to have a concave cross section in order to improve excavation performance, and may be inclined in the excavation direction [forward rotation direction (arrow A direction)].

On the upper side of the consolidation cam 4 (on the side of the main spiral blade), the same spiral direction as the main spiral blade 2A provided on the outer circumference of the rod 2 is provided.
Auxiliary spiral blades 8A, 8B are provided continuously on the cam surfaces 5A, 5B. By the main spiral blade 2A and the auxiliary spiral blades 8A and 8B, the earth and sand excavated by the excavating portions 7A and 7B are fed upward along the rod 2 when the consolidation cam 4 is normally rotated, and the earth and sand are fed from the rod 2 side when the converse rotation is performed. It is designed to be fed to the cam surfaces 5A and 5B. The compacting cam 4 has a semicircular shape that narrows toward the tip even when viewed from the side surface.

In order to distribute the earth and sand conveyed by the main spiral blade 2A to the two cam surfaces 5A, 5B in a substantially uniform manner and to supply them in good balance, the main spiral blade 2A and the auxiliary spiral blade 8A,
8B is not continuous but is discontinuous. Particularly in the illustrated example, between the main spiral blade 2A and the auxiliary spiral blades 8A and 8B,
A predetermined gap S is formed in the axial direction of the rod 2, and the earth and sand conveyed from one main spiral blade side is distributed to the two auxiliary spiral blade sides through the gap S. The dimension Lb of the gap S in the rod axis direction is preferably 1/2 or less than the dimension La of the auxiliary spiral blades 8A, 8B in the rod axis direction. The tip of the main spiral blade 2A and the auxiliary spiral blades 8A, 8
Instead of forming a gap S in the rod axial direction between the blade tip of B and the blade tip of B, the blade tip of the main spiral blade 2A and the blade tips of the auxiliary spiral blades 8A and 8B are displaced in the circumferential direction, and a circumferential direction is provided between both blade tips. A predetermined gap may be formed in the. In this case, the dimension Lb of the gap in the rod axial direction is zero.

The outer diameter Da of the consolidation cam 4 is equal to the main spiral blade 2
The outer diameter D of A is preferably equal to or larger than that.
The pitch of the auxiliary spiral blades 8A and 8B is preferably smaller than the pitch of the main spiral blade 2A. Further, the auxiliary spiral blades 8A and 8B are preferably formed to have a smaller diameter than the main spiral blade 2A. In this case, the auxiliary spiral wing 8
The outer diameters of A and 8B are gradually reduced upward from the upper ends of the cam surfaces 5A and 5B, and the outer diameter d of the upper ends of the auxiliary spiral blades 8A and 8B is the outer diameter D of the main spiral blade 2A or the compression cam. 4 is formed smaller than the outer diameter Da. As a result, a gap Sr is generated between the hole wall (inner wall) of the excavation hole and the auxiliary spiral blades 8A and 8B, and the gap Sr reduces the consolidation of the earth and sand by the auxiliary spiral blades 8A and 8B. Passage of earth and sand from the main spiral blade 2A side to the consolidation cam 4 side (distribution)
Can be better.

In FIG. 2, reference numeral 19 is a chip made of cemented carbide or the like provided on the ridges of the excavated portions 7A and 7B of the consolidation cam 4. The tip 19 is divided into a plurality of pieces and attached by welding, bolts or the like, and can be replaced when worn. Chip 1 that can be replaced in this way
By providing 9, the overall durability can be improved and the excavation performance can be maintained.

Next, the operation of the auger screw 1 having the above structure will be described. When excavating the ground, the auger screw 1 is normally rotated (clockwise rotation = rotation in the direction of arrow A), and is excavated from the tip side to the ground to excavate the ground.
In this excavation process, the ground is excavated by the excavation portions 7A and 7B of the consolidation cam 4, and the excavated earth and sand (ground soil) is conveyed upward by the spiral blade portions 8A, 8B, 2A and 2B and is conveyed to the ground. .

Once the ground has been excavated to the required depth, the rotation direction of the auger machine is switched and the auger screw 1
Is reversely rotated (right rotation = rotation in the direction of arrow B). At this time, earth and sand (mixed soil) obtained by adding ground improvement materials such as mountain sand and cement to earth and sand carried out or dug up on the ground is put into the excavation hole through the hole mouth.

The loaded earth and sand is conveyed downward by the main spiral blade 2A, and is further fed to the auxiliary spiral blade 8 of the auger head 3.
It is sent to each cam surface 5A, 5B by A, 8B. In this case, the earth and sand conveyed by the main spiral blade 2A are distributed substantially evenly to the two auxiliary spiral blades 8A and 8B through the gap S between the main spiral blade 2A and the auxiliary spiral blades 8A and 8B. It is sent to the two cam surfaces 5A and 5B with good balance. Further, the diameter d on the upper end side of the auxiliary spiral blades 8A, 8B is the outer diameter D, Da of the main spiral blade 2A or the compression cam 4.
By being formed to be slightly smaller than the above, the earth and sand are suppressed from being radially consolidated by the auxiliary spiral blades 8A and 8B, and the earth and sand are smoothly supplied from the main spiral blade side to the consolidation cam side. Then, the earth and sand are pushed laterally (outward in the radial direction of the excavation hole, in the direction of arrow F) by both cam surfaces 5A and 5B to be consolidated. The earth and sand are also sent to the hole bottom on the tip side along the outer circumference of the consolidation cam 4, and are compacted by the tip sides of the cam surfaces 5A, 5B.

In this case, the consolidation cam 4 receives the consolidation reaction force from the hole bottom side, but receives more consolidation reaction force from the hole wall side (radial direction of the drilled hole), so that the conventional earth auger method is used. The auger screw 1 is not pushed up unintentionally like. Therefore, it is not necessary to apply a load against the consolidation reaction force to the auger screw 1, so that the auger machine can be downsized without being forced to upsize. The degree of consolidation can be inferred from the torque applied to the auger machine, etc. By gradually raising the auger screw 1 while maintaining the desired compaction density,
Create a columnar consolidation foundation.

As described above, according to the auger screw 1, the rod 2 which is vertically moved and rotated by the auger machine, and the spiral which is provided on the outer periphery of the rod 2 and conveys the earth and sand along the rod 2 by the rotation of the rod 2. Wings 2A, 2
B and an auger head 3 provided at the tip of the rod 2, the auger head 3 excavates the ground by the forward rotation of the rod 2 and the earth and sand outwardly of the excavation hole by the reverse rotation of the rod 2. A compacting cam 4 having a plurality of cam faces 5A, 5B that are pressed and compacted is provided, and the spiral blades 2A, 2B have a number of threads corresponding to the number of the cam faces 5A, 5B of the compacting cam 4 (in the present embodiment, in the present embodiment). 2), and each spiral wing 2A, 2
Since B is continuous with each cam surface 5A, 5B, it is possible to efficiently feed the sand into each cam surface 5A, 5B, and to easily and efficiently form the columnar consolidation foundation with sufficient strength that has a lateral spread. Can be well constructed.

When the ground is extremely soft, such as mud, the auger screw 1 is rotated while rotating the consolidation cam 4 in the consolidation direction (reverse rotation direction) without excavating the ground as described above. Directly into the ground (ground improvement material is not supplied in this process), and when it has been inserted to a predetermined depth, ground improvement material such as mountain sand is supplied to start consolidation, and then the same consolidation step as above. The columnar consolidation foundation may be formed by.

3A and 3B are views showing an auger screw according to a second embodiment of the present invention. FIG. 3A is a side view of a lower portion of the auger screw, and FIG. 3B is a view of the auger head seen from another direction. A side view, (c) is a front view of the auger head as seen from below, and FIG. 4 is an enlarged side view of essential parts of the auger screw of FIG. In the present embodiment, the same parts as those in the previous embodiment are designated by the same reference numerals.

The auger screw 1 shown in the drawing has a rod 2 which is vertically moved and rotated by an auger machine (not shown). Two spiral wings (main spiral wings) 2A and 2B for transporting earth and sand along the rod 2 by the rotation of the rod 2 are provided on the outer periphery of the rod 2, and the tip of the rod 2 has Auger head 3 with bolt 20
Is detachably attached.

A compacting cam 4 is provided at the tip of the auger head 3. The consolidation cam 4 excavates the ground by forward rotation of the rod 2 [rotation in the direction of arrow A in the figure (c) = clockwise rotation] and reverse rotation of the rod 2 [rotation in the direction of the arrow B in the figure (c) = counterclockwise rotation]. ], The two cam surfaces 5A for pressing and consolidating the earth and sand radially outward of the drill hole [direction of arrow F in Fig. (C)],
Have 5B.

The compacting cam 4 faces a pair of cam portions 6A and 6B having substantially semicircular cross sections having cam surfaces 5A and 5B each having a contour curve having a substantially arcuate cross section, in opposite directions with respect to the center of rotation C. It is formed in a cross-sectional shape that is eccentric by the same amount of eccentricity. Further, as shown in FIG. 3C, the consolidation cam 4 has a basic circle Dx having an outer diameter substantially the same as the outer diameter of the rod 2, and the cam surfaces 5A and 5B are reversed on the basic circle Dx. One end on the rotation side (arrow B direction side ) is in contact. Cam surfaces 5A, 5
The portions connecting the other end of B and the base circle Dx are excavation portions 7A and 7B for excavating the ground. The excavation parts 7A and 7B are
In order to improve the excavation performance, it is preferably formed in a concave cross section, and the excavation direction [forward rotation direction (arrow A
Direction)].

On the upper side of the consolidation cam 4, two spiral blades (auxiliary spiral blades) 8A, 8B continuous with the spiral blades 2A, 2B provided on the outer circumference of the rod 2 are continuous with the respective cam surfaces 5A, 5B. Is provided. These spiral wings 2A, 2B, 8A, 8
By B, the excavation parts 7A, 7A, 7
The earth and sand excavated in B is sent to the upper side along the rod 2, and the earth and sand are sent from the rod 2 side to the cam surfaces 5A and 5B at the time of reverse rotation. The compacting cam 4 has a semicircular shape that narrows toward the tip even when viewed from the side surface. Chips 19 made of cemented carbide or the like are provided on the ridges of the excavated portions 17A and 17B of the consolidation cam 14.

Next, the operation of the auger screw 1 having the above structure will be described. When excavating the ground, the auger screw 1 is normally rotated (clockwise rotation = rotation in the direction of arrow A), and is excavated from the tip side to the ground to excavate the ground.
In this excavation process, the ground is excavated by the excavation portions 7A and 7B of the consolidation cam 4, and the excavated earth and sand (ground soil) is conveyed upward by the spiral blade portions 8A, 8B, 2A and 2B and is conveyed to the ground. .

Once the ground has been excavated to the required depth, the rotation direction of the auger machine is switched and the auger screw 1
Is reversely rotated (right rotation = rotation in the direction of arrow B). At this time, earth and sand (mixed soil) obtained by adding ground improvement materials such as mountain sand and cement to earth and sand carried out or dug up on the ground is put into the excavation hole through the hole mouth.

The earth and sand that have been thrown in are composed of two spiral blades 2A and 2A.
B is conveyed downward by B, and is further fed to each cam surface 5A, 5B by the spiral blades 8A, 8B of the auger head 3, and is laterally (radially outward of the drill hole, arrow F direction) by both cam surfaces 5A, 5B. ) Is pressed and consolidated. The earth and sand are also sent to the hole bottom on the tip side along the outer circumference of the consolidation cam 4, and are compacted by the tip sides of the cam surfaces 5A, 5B.

In this case, the consolidation cam 4 receives the consolidation reaction force from the hole bottom side, but receives more consolidation reaction force from the hole wall side (radial direction of the drilled hole), so that the conventional earth auger method is used. The auger screw 1 is not pushed up unintentionally like. Therefore, it is not necessary to apply a load against the consolidation reaction force to the auger screw 1, so that the auger machine can be downsized without being forced to upsize. The degree of consolidation can be inferred from the torque applied to the auger machine, etc. By gradually raising the auger screw 1 while maintaining the desired compaction density,
Create a columnar consolidation foundation.

As described above, according to the auger screw 1, the rod 2 which is moved up and down and rotated by the auger machine, and the earth and sand which are provided on the outer periphery of the rod 2 and which are rotated by the rod 2 are conveyed along the rod 2. Spiral wing 2A
And an auger head 1 provided with an auger head 3 provided at the tip of the rod 2, in the auger head 3, the earth is excavated by the forward rotation of the rod 2 and the earth and sand is excavated by the reverse rotation of the rod. Is provided with a plurality of cam surfaces 5A, 5B which are pressed outwards in the radial direction to consolidate, and auxiliary spiral blades 8A, 8B continuous with the cam surfaces 5A, 5B of the consolidation cam 4 are provided. Since the spiral blade 2A and the auxiliary spiral blades 8A and 8B are continuous, each cam surface 5A,
The earth and sand can be sent independently to the 5B, and a columnar consolidation foundation having a sufficient strength and extending in the lateral direction can be easily and efficiently formed. Further, since the auxiliary spiral blades 8A and 8B are formed to have a smaller diameter than the main spiral blade 2A, it is possible to improve the passage or flow of the sediment from the main spiral blade 2A toward the consolidation cam 4.

FIG. 5 shows a modification of the auger screw. The auger screw 1 is provided with spike chips 29 made of cemented carbide or the like in a row or a plurality of rows on the ridge portions of the excavating portions 7A and 7B of the consolidation cam 4, so that it is suitable for excavating concrete. Has become.

The embodiments of the present invention have been described in detail above with reference to the drawings. However, the present invention is not limited to the above embodiments, and various design changes and the like without departing from the gist of the present invention. Is possible. For example, in the above embodiment, the consolidation cam having two cam surfaces is illustrated, but three or more cam surfaces may be provided. The attachment of the auger head to the tip of the rod may be performed with a pin instead of the bolt.

[0036]

According to the present invention described above, the following effects can be obtained.

(1) According to the auger screw of the first aspect, a rod that is vertically moved and rotated by an auger machine, and a main spiral that is provided on the outer periphery of the rod and that conveys earth and sand along the rod by rotation of the rod. In an auger screw provided with blades and an auger head provided at the tip of the rod, the auger head excavates the ground by the forward rotation of the rod and the earth rotates outside the excavation hole in the radial direction of the excavation hole by the reverse rotation of the rod. an auxiliary spiral vane continuous with the cam surface on the upper side of the piezoelectric dense cam provided with a compaction cam having a lateral substantially arcuate cross section of a plurality of cam surfaces for compaction is pushed toward provided,
The consolidation cam has a basic circle with an outer diameter substantially the same as the outer diameter of the rod, and one end on the reverse rotation side of each cam surface is in contact with this basic circle, and the portion connecting the other end of the cam surface and the basic circle is It is an excavation part for excavating the ground, and the consolidation cam has a semicircular shape that narrows toward the tip when viewed from the side, and between the main spiral blade and the auxiliary spiral blade in the axial or circumferential direction of the rod. Since a predetermined gap is formed, it is possible to feed the sand into each cam surface efficiently and in a well-balanced manner, and it is possible to easily and efficiently form a columnar consolidated foundation with sufficient strength that spreads in the lateral direction. it can.

(2) According to the auger screw of the second aspect, since the auxiliary spiral blade is formed to have a smaller diameter than that of the main spiral blade, the sand flow from the main spiral blade toward the consolidation cam is improved. be able to.

(3) According to the auger screw of the third aspect, a rod which is moved up and down and rotated by an auger machine, and a spiral blade which is provided on the outer periphery of the rod and conveys earth and sand along the rod by the rotation of the rod. And an auger screw provided with an auger head provided at the tip of the rod, the auger head excavates the ground by forward rotation of the rod, and reverse rotation of the rod scavenges earth and sand radially outward of the excavation hole. to push the transverse cross section arcuate compaction cam having a plurality of cam surfaces for compaction is provided by the consolidating cam has a generally base circle having the same outer diameter as the outer diameter of the rod, on the base circle One end of each cam surface on the reverse rotation side is in contact, and the part that connects the other end of the cam surface and the base circle is the excavation part for excavating the ground, and the consolidation cam is a semicircular shape that narrows toward the tip when viewed from the side Before, As many spiral blades are provided as the number of threads corresponding to the number of cam surfaces of the consolidation cam, and each spiral blade is continuous with each cam surface, it is easy to form a columnar consolidation foundation of sufficient strength that spreads in the lateral direction. Can be created.

[Brief description of drawings]

FIG. 1 is a view showing an auger screw according to a first embodiment of the present invention, (a) is a side view of a lower portion of the auger screw, and (b) is a side view of the auger head seen from another direction. , (C) are front views of the auger head as seen from below.

FIG. 2 is an enlarged side view of a main part of the auger screw of FIG.

3A and 3B are views showing an auger screw according to a second embodiment of the present invention, FIG. 3A is a side view of a lower portion of the auger screw, and FIG. 3B is a side view of the auger head seen from another direction. , (C) are front views of the auger head as seen from below.

FIG. 4 is an enlarged side view of a main part of the auger screw of FIG.

FIG. 5 is an enlarged side view of an essential part showing a modified example of the auger screw.

[Explanation of symbols]

1 auger screw 2 rod 2A Main spiral wing 3 auger head 4 Consolidation cam 5A, 5B cam surface 8A, 8B auxiliary spiral wing

Claims (3)

(57) [Claims] 1. A rod which is vertically moved and rotated by an auger machine, and a main spiral blade which is provided on the outer periphery of the rod and conveys earth and sand along the rod by rotation of the rod.
In an auger screw having an auger head provided at the tip of the rod, the auger head excavates the ground by forward rotation of the rod and pushes earth and sand radially outward of the excavation hole by reverse rotation of the rod. in an auxiliary spiral vane continuous with the cam surface on the upper side of the piezoelectric dense cam provided with a compaction cam having a lateral substantially arcuate cross section of a plurality of cam surfaces for compaction provided, wherein the consolidating cam substantially to the outer diameter of the rod It has a basic circle with the same outer diameter, one end on the reverse rotation side of each cam surface contacts this basic circle, and the part connecting the other end of the cam surface and the basic circle is the excavation part for excavating the ground, the consolidation cam Has a semicircular shape that narrows toward the tip when viewed from the side, and a predetermined gap is formed between the main spiral blade and the auxiliary spiral blade in the axial direction or the circumferential direction of the rod. And auger screw. 2. The auger screw according to claim 1, wherein the auxiliary spiral blade has a smaller diameter than the main spiral blade. 3. A rod that is vertically moved and rotated by an auger machine, a spiral blade that is provided on the outer circumference of the rod and conveys earth and sand along the rod by rotation of the rod, and an auger head that is provided at the tip of the rod. in auger screw having bets, the auger head, forward rotation in drilling ground and lateral substantially arcuate cross section of the plurality of compaction is pushed radially outward of the drill holes with sand in the reverse rotation of the rod of said rod A compression cam having a cam surface of is provided, the compression cam has a basic circle having an outer diameter substantially the same as the outer diameter of the rod, and one end on the reverse rotation side of each cam surface is in contact with this basic circle.
The part connecting the other end of the cam surface and the base circle is an excavation part for excavating the ground, the consolidation cam has a semicircular shape that narrows toward the tip as seen from the side, and the spiral blade has a cam of the consolidation cam. An auger screw characterized in that it is provided with the number of threads corresponding to the number of surfaces, and that each spiral blade is continuous with each cam surface.