JP6347885B1 - Drilling and stirring tools - Google Patents

Abstract

[PROBLEMS] To deal with the tightening of excavation and improved soil regardless of the type of surrounding ground, and to minimize the engagement depth of the co-rotation prevention wing to the surrounding ground or prevent co-rotation without engaging. Excavation that can make the wings immobile with respect to the direction of rotation, can suppress damage and deterioration of the wings and soil adhesion to the wings as much as possible, can reliably prevent the co-rotation phenomenon, and dramatically improve the stirring efficiency Provide a stirrer. An excavation / agitation shaft 1 extending in the vertical direction, an excavation blade 2 for excavating the ground supported by the lower end of the excavation / agitation shaft 1, and an outer peripheral surface of the excavation / agitation shaft 1 for excavation / agitation. A drive agitating blade 3 that rotates integrally with the shaft 1 and at least two or more bosses loosely fitted around the outer periphery of the excavating / stirring shaft 1 are straddled and formed outwardly to form an arc shape. And the rotation center line of the arc stirring blade 5 is in a position eccentric with respect to the rotation center line of the excavation / stirring shaft 1. [Selection] Figure 1

Description

  The present invention relates to an excavation / stirring tool for a ground improvement device.

  Conventionally, the excavation / stirring tool of the ground improvement device includes a driving stirrer that rotates integrally with the excavation / stirring shaft to stir the excavated soil, and various co-rotation preventing blades to improve excavation / stirring efficiency. The one with is proposed.

  Generally, the co-rotation prevention wing is formed in a horizontal plate shape, supports the base end on the excavation / stirring shaft, and uses the horizontal end portion as the inner peripheral wall of the excavation hole (hereinafter also simply referred to as the surrounding ground). By engaging and fixing, the rotation of the excavation / stirring shaft is fixed, and the rotational resistance force to the excavated soil, improved material, improved soil, etc. (hereinafter also simply referred to as excavated / improved soil) existing in the vicinity of the drive agitating blade. To generate a “shearing force” to prevent the so-called co-rotation phenomenon that the excavated and improved soil rotates together with the driving agitating blade.

  However, the excavation / stirring tool provided with such a horizontal plate-shaped co-rotation preventing blade has the following problems in improving the ground.

  In other words, the co-rotation prevention wing projects and engages the horizontal end with the ground around the excavation hole and penetrates along the vertical direction of the excavation hole, resulting in a large physical load and damage deterioration. I was expedited.

  In addition, once the co-rotation prevention wing is engaged and fixed to the ground around the excavation hole, a large pressure input is required during the drilling / stirring tool penetration operation, and a large frictional force is required during the pulling out operation. It became large and caused construction problems.

  In order to deal with the problem of damage deterioration and penetration / pull-out resistance, a horizontal shaft is formed by using an eccentric shaft with the rotating shaft (hereinafter also referred to as the rotation center line) of the co-rotation preventing blade supported at one end being eccentric. An excavation / stirring tool provided with a mechanism (hereinafter also referred to as a crank-like mechanism) for intermittently engaging (hereinafter also referred to as a crank-like engagement) the horizontal end portion of the anti-rotation blade with the surrounding ground of the excavation hole. It has been proposed (see, for example, Patent Document 1 to Patent Document 5).

  Among the excavation / stirring tools provided with such a crank mechanism, for example, the techniques disclosed in Patent Document 3 and Patent Document 4 support three or more co-rotation preventing blades along the axial direction of the eccentric shaft, The horizontal end of the co-rotation preventing wing can be reliably engaged with the surrounding ground in a crank-like manner.

  In addition, the technique disclosed in Patent Document 5 is configured such that the rotation center line of the co-rotation prevention blade is inclined to be an eccentric shaft, and the co-rotation prevention blade is supported by a boss part loosely fitted to the eccentric shaft. Yes.

  According to this technology, when excavating and rotating the agitation shaft, agitation and improvement are achieved by using both the crank-like engagement of the co-rotation prevention blade with the surrounding ground and the vibration in the inclination direction along the inclination of the eccentric shaft. It is said that the co-rotation phenomenon can be prevented by moving the soil up and down the co-rotation prevention wing.

JP-A-5-132926 Japanese Patent Laid-Open No. 5-1739639 JP-A-6-26032 Shinshin No. 3024353 JP-A-5-179640

  By the way, there are various types of ground to be improved, and when classified according to the soil characteristics, comparisons are made between relatively soft and brittle soft ground made of mud, viscous soil containing a large amount of water and loose sand, gravel mixed with cobblestones and bedrock. Hard ground that is hard and strong, and these soft and hard grounds are roughly divided into alternate layers in a layered manner.

  In the improvement construction of the ground having various soil properties as described above, the excavation / stirring tool disclosed in Patent Document 1 and Patent Document 2 is around the joint rotation prevention wing when the improvement construction target is a soft ground. In intermittent engagement with the ground, the co-rotation prevention wing cannot be fixed, causing a co-rotation phenomenon.

  Further, according to the excavation / stirring tools disclosed in Patent Document 3 and Patent Document 4, since the degree of engagement fixation varies depending on the soil characteristics of the ground, the horizontal end portions of a plurality of co-rotation preventing blades according to the ground It is necessary to consider in advance the depth of engagement with the surrounding ground.

  Therefore, in the excavation / stirring tools disclosed in Patent Document 3 and Patent Document 4, in the case where the alternate layer ground having different soil characteristics is improved along with the penetration / drawing construction, the horizontal end portions of a plurality of co-rotation preventing blades are used. It is practically impossible to design the engagement depth of each according to the alternate layer ground.

  In addition, the installation of multiple anti-rotation blades on the excavation / stirring tool will increase the contact area between the blade surface and the excavation / improvement soil and increase the soil adhesion of the excavation / improvement soil to the anti-rotation blade. As a result, the passage of excavation and improved soil between wings was hindered, and the co-rotation phenomenon was promoted.

  Further, in the excavation / stirring tool disclosed in Patent Document 5, the co-rotation preventing blade supported at one end with respect to the excavation / stirring shaft is caused by the vibration caused by the rotation of the eccentric shaft in the state of being engaged with the surrounding ground. The blade tip was forcibly moved in the vertical direction, which accelerated the damage deterioration of the co-rotation preventing blade.

  Furthermore, the co-rotation preventing blade in the excavation / stirring tool disclosed in Patent Document 5 increases the sliding friction force by increasing the contact load between the peripheral surface of the eccentric shaft and the inner peripheral surface of the boss part loosely fitted on the eccentric shaft. Therefore, the rotation of the excavation / stirring shaft is transmitted to the boss portion, and the loosely-fitted state of the common rotation preventing blade cannot be maintained, and as a result, the common rotation preventing blade may rotate together with the drive stirring blade.

  Further, in the excavation hole, the excavation / improvement soil is tightened due to an increase in the density of excavation / improvement soil accompanying excavation / mixing work.

  For this reason, the excavation / stirring tools of Patent Documents 1 to 5 not only generate co-rotation by further promoting soil adhesion to the wing in the tightened excavation hole, Construction failures have been caused, such as increasing the frictional resistance during the pulling operation and inadvertently regulating the rotation of the drive rotor blades.

  Furthermore, in the excavation / stirring tools of Patent Documents 1 to 5 based on the engagement with the surrounding ground, the engagement depth of the co-rotation preventing wing is increased in order to obtain the rotation resistance force by the intermittent engagement state. It is necessary to cause vibration by the engagement depth and pressure input at the time of intrusion / extraction, which will cause the surrounding ground to collapse, and the surrounding soil that is not agitated and mixed will invade the outer periphery of the improved body. The efficiency was lowered.

  Thus, the co-rotation prevention blade in the conventional excavation / stirring tool cannot cope with the tightening of any ground or excavation / improvement soil, and has a probability of being in a stationary state with momentary engagement with the surrounding ground. Even if it can be lowered or engaged, problems such as wing breakage deterioration and non-uniform stirring during intrusion and extraction operations will occur, and soil adhesion to the wing surface will increase, causing a co-rotation phenomenon. It was not something that could be reliably prevented, and the workability was reduced.

  The present invention has been made in view of such circumstances, and can be adapted to excavation / improvement soil tightening regardless of the type of surrounding ground, and the engagement depth of the co-rotation preventing wing to the surrounding ground can be reduced. The co-rotation prevention wing can be kept stationary with respect to the direction of rotation without minimizing or engaging with it, and the damage to the wing and soil adhesion to the wing can be suppressed as much as possible. Provided is a drilling / stirring tool capable of improving stirring performance for uniform stirring throughout the improved body.

In order to solve the above-mentioned conventional problems, the excavation / stirring tool according to the present invention is (1) a drilling / stirring tool for performing ground improvement by kneading excavated soil and improvement material while excavating and stirring the ground. , A drilling / stirring shaft extending vertically, a drilling blade supported at the lower end of the excavation / stirring shaft, excavating the ground, and supported by an outer peripheral surface of the drilling / stirring shaft, A drive stirring blade that rotates integrally, and an arc-shaped stirring blade that is straddled on the outer peripheral surface of at least two or more boss portions loosely fitted around the outer periphery of the excavation / stirring shaft and bulges outward to form an arc shape And the arc-shaped stirring blade is an outermost floating stirring blade rotating in a floating state with respect to the excavation / stirring shaft, and the rotation center line of the arc-shaped stirring blade is the rotation center of the excavation / stirring shaft in particular have a feature in the eccentric position is inclined relative to the line That.

Moreover, the excavation / stirring tool according to the present invention is also characterized by the following points.
(2) In an excavation / stirring tool for ground improvement by kneading excavated soil and improvement material while excavating / stirring the ground, a drilling / stirring shaft extending vertically and a lower end of the excavation / stirring shaft Supported by the excavation blade for excavating the ground, the drive agitating blade supported by the outer peripheral surface of the excavation / stirring shaft and rotating integrally with the excavation / stirring shaft, and loosely fitted around the outer periphery of the excavation / stirring shaft An arc stirring blade straddling the outer peripheral surfaces of the at least two boss portions and bulging outward to form an arc shape, and the arc stirring blade is free to move with respect to the excavation and stirring shaft An outermost floating stirring blade rotating in a state, and the rotation center line of the arc stirring blade is at least two bosses straddling the arc stirring blade with respect to the rotation center line of the excavation / stirring shaft Excavation between the top and bottom bosses It is in the tilted so as to intersect the rotational axis of the stirring shaft eccentric position.
(3) The arc-shaped stirring blade has a twisted shape or a shape inclined with respect to the coaxial direction with respect to the rotation center line of the arc-shaped stirring blade.

According to the onset bright, the excavation and stirring device for performing ground improvement by kneading the excavated soil material and the modifying material with excavation and stirred soil, and excavation and stirring shaft that extends in the vertical direction, the excavation and A drilling blade supported at the lower end of the stirring shaft and excavating the ground; a driving stirring blade supported on the outer peripheral surface of the drilling / stirring shaft and rotating integrally with the drilling / stirring shaft; and an outer periphery of the drilling / stirring shaft An arc-shaped stirring blade straddling the outer peripheral surface of at least two or more boss portions loosely fitted around, and bulging outward to form an arc shape, the arc-shaped stirring blade having the excavation / stirring shaft The outermost agitating agitating blade that rotates in an idling state with respect to the arc, and the rotation center line of the arc-shaped agitating blade is located eccentric to the rotation center line of the excavation and agitation shaft. Corresponding to the tightening of excavated and improved soil The engagement depth of the co-rotation prevention wing to the surrounding ground is minimized, or the co-rotation prevention wing is made stationary with respect to the rotation direction without being engaged, and the blade is damaged and deteriorated and the soil adheres to the wing. Can be suppressed as much as possible, the co-rotation phenomenon can be surely prevented, and the stirring performance of uniform stirring throughout the improved body can be improved.

  Here, the distribution tendency of the shearing force for the excavated / improved soil (hereinafter also referred to as the improved body) in the excavation hole depends on the soil characteristics, the shape of the agitating blade, the position of the agitating blade on the excavating / stirring shaft, etc. It is defined as the “shear line” that determines the range of agitation that occurs in excavated and improved soil. FIG. 5 is an explanatory diagram showing a concept of “shear line” in excavation / improved soil in the excavation hole. FIG. 4 is an explanatory view showing an operating state of the excavation / stirring tool as viewed in the axial direction.

  As shown in FIG. 5, the “shear line” means excavation / improved soil that is swung around the blade under the influence of the rotational force of the drive stirring blade due to its fluidity and adhesiveness, etc. Excavation / improvement soil in a stationary state without being directly affected by the rotary drive blade, or in a state in which the rotation is delayed due to the rotational effect of the drive agitating blade indirectly (hereinafter also simply referred to as a substantially stationary state) It is also a line that determines the shear fracture surface of excavated and improved soil.

  That is, the agitation zone of the excavation / improved soil divided by the “shear line” in the excavation hole is the rotation agitation zone rotating in the vicinity of the drive agitation blade (in FIG. 5 (a) and FIG. 5 (b), the shear line). 5) and a stationary stirring region in a stationary or rotationally retarded state without being affected by the drive stirring blade (in FIG. 5 (a) and FIG. 5 (b), it is outside by a shear line). (Indicated by the hatched area of the dashed-dotted line).

  Of these, the static agitation zone is more easily formed near the surrounding ground in the excavation hole, that is, the outer periphery of the improved body, because the influence of the drive rotation of the drive agitation blade is not transmitted to the excavation / improvement soil as the distance from the drive agitation blade increases. There is a tendency.

  That is, in the excavation / stirring tool according to the present invention, as shown in FIGS. 5 (a) and 5 (b), an arc stirring blade having an eccentric rotation center line is disposed in the vicinity of the surrounding ground as the outermost floating stirring blade. By providing the configuration, the arc-shaped stirring blade is stationary as well as the surrounding ground against the sliding frictional force between the inner peripheral surface of the plurality of boss portions straddling the stirring blade and the outer peripheral surface of the excavation / stirring shaft. Effectively obtains rotational resistance force from the stirring zone, becomes stationary with respect to the rotation direction, and functions as a co-rotation preventing blade that generates a “shear line” with the drive stirring blade.

  Moreover, as shown in FIG. 4, the arc-shaped agitating blade stationary in the rotating direction always vibrates according to the amount of eccentricity as the excavation / stirring shaft rotates, and the vibration suppresses soil adhesion to the blade. A new agitation that makes full use of the vibration characteristics of the arc-shaped agitating blades, causing an "adhesion suppression action" and a "clamping prevention action" that prevents clogging due to the increase in the density of excavated and improved soil in the borehole Create an effect.

  Here, from the viewpoint of stirring efficiency, the stationary stirring area divided by the “shear line” has the stationary excavation / improved soil as described above, so the outer periphery of the improved body has lower stirring efficiency. It can be said.

  In contrast to the stationary excavation / improved soil existing in such a static agitation zone, the arc-shaped agitating blade transmits vibration stress to the stationary excavation / improved soil.

  Specifically, the arc-shaped stirring blade has a blade portion arranged in the stationary stirring zone while maintaining an immobile posture in the rotational direction of the drilling / stirring shaft as a whole when viewed in the axial direction of the drilling / stirring shaft. Since it vibrates so as to perform a substantially circular motion (movement of both ends of the arc-shaped stirring blade in FIG. 4) according to the amount of eccentricity, “vertical shear rotation stirring” can be performed.

  In other words, the arc-shaped stirring blade functions as a co-rotation preventing blade that becomes stationary with respect to the rotation direction of the excavation / stirring shaft by receiving resistance from the excavation / improvement soil in the stationary stirring region, but with an eccentric amount. It will function as a vertical shear rotary agitating blade that locally and partially agitates the excavated and improved soil in the static agitation zone by vibrated vibration according to the conditions.

  As a result, the excavator / stirring tool can reliably generate a “shear line” between the driving stirring blade and the arc-shaped stirring blade, and can ensure a “co-rotation prevention effect”. During operation, the frictional resistance can be reduced as much as possible, and the passage of excavation and improved soil between the blades can be promoted, and the stirring effect of uniform stirring throughout the improved body is improved.

  Furthermore, the vibration force of the arc stirring blade is transmitted as a reaction force to the excavation / stirring shaft through the boss. As a result, the excavation blade and the drive stirring blade are vibrated, thereby preventing "soil adhesion suppression" and "tightening prevention". The “operation” can be promoted, the excavation speed can be improved, and the construction speed can be improved.

Further, according to the present invention, the maximum improvement diameter by the arcuate stirring blade, if under drilling blade diameter or less, at the time of intrusion-abstraction from the surrounding ground without engaging fixing an arcuate agitating blade into the surrounding ground friction Can be prevented, and a rotational resistance force can be obtained from the stationary agitation zone to obtain a stationary state.

  Furthermore, it is possible to vibrate the arc-shaped stirring blades that have the maximum vibration range of the arc-shaped stirring blades within the drilling hole diameter, and promote the “soil adhesion inhibiting action” and the “tightening prevention action” to prevent “co-rotation prevention”. "Effect" can be solid and construction speed can be greatly improved.

According to the invention of claim 1 , since the rotation center line of the arc-shaped stirring blade is inclined with respect to the rotation center line of the excavation / stirring shaft, the arc-shaped stirring blade is substantially left and right (inclined direction). It can be vibrated, forcibly moving the excavated and improved soil in the vicinity of the arc stirring blades in the left-right direction, and promotes "soil adhesion suppression action" and "tightening prevention action", and "co-rotation prevention effect" Can occur.

According to a second aspect of the present invention, the rotation center line of the arc-shaped stirring blade has at least two bosses over which the arc-shaped stirring blade is straddled with respect to the rotation center line of the excavation / stirring shaft. Since the upper and lower bosses are inclined so as to intersect the rotation center line of the excavation / stirring shaft, the arc stirring blades are raised not only in the substantially horizontal direction but also in the substantially vertical direction. It can be vibrated, and the “soil adhesion inhibiting action” and the “tightening prevention action” can be further promoted to make the “corotation prevention effect” more solid and improve the construction speed.

According to the invention of claim 3 , the arc-shaped stirring blade has a twisted shape or a shape inclined with respect to the coaxial direction with respect to the rotation center line of the arc-shaped stirring blade. In addition to soil adhesion suppression, tightening prevention, and co-rotation prevention, the arc-shaped agitating blades are driven using the excavation / improvement soil passage resistance that accompanies excavation and agitation tools. It can be rotated so that the rotating state is different from the rotating state of the agitating blade, and the complex relative rotational agitation is realized by the arc-shaped agitating blade and the drive agitating blade, and the excavation and improved soil can be mixed well. Can be secured.

It is a side view which shows the basic composition of the excavation and stirring tool concerning Example 1. FIG. FIG. 6 is a schematic plan view showing the structure of an eccentric portion in the excavation / stirring shaft according to the first and second embodiments. It is a typical top view which shows the eccentric shaft structure of the digging and stirring tool concerning Example 1 and a modification. It is a top view which shows the operating state of the excavation and stirring tool concerning Example 1. FIG. It is a schematic diagram which shows the "shear line" of excavation and improved soil in a excavation hole. It is a side view which shows the structure of the excavation and stirring tool concerning Example 1. FIG. It is a top view which shows the rotation locus | trajectory of the excavation / stirring tool concerning Example 1. FIG. It is a side view which shows the structure of the excavation and stirring tool concerning Example 2. FIG. It is a side view which shows the structure of the excavation and stirring tool concerning Example 3. FIG. It is typical explanatory drawing which shows the structure of the eccentric part in the excavation and stirring shaft concerning Example 3 and Example 4. FIG. It is a side view which shows the structure of the excavation and stirring tool concerning Example 4. FIG. It is a side view which shows the structure of the excavation / stirring tool concerning Example 5. FIG. It is typical explanatory drawing which shows the structure of the eccentric part in the excavation and stirring shaft concerning Example 5 and Example 6. FIG. It is a side view which shows the structure of the excavation / stirring tool concerning Example 6. FIG. It is a side view which shows the structure of the excavation and stirring tool concerning Example 7. FIG. FIG. 10 is a side view showing the configuration of a digging / stirring tool according to Example 8. It is explanatory drawing which shows an example of the arc-shaped stirring blade in the excavation and stirring tool concerning this invention. It is explanatory drawing which shows an example of the various stirring blades in the excavation and stirring tool concerning this invention. It is explanatory drawing which shows an example of the various stirring blades in the excavation and stirring tool concerning this invention. It is explanatory drawing which shows an example of the various stirring blades in the excavation and stirring tool concerning this invention. It is explanatory drawing which shows an example of the various stirring blades and excavation blades in the excavation and stirring tool concerning this invention. It is a side view which shows the ground improvement apparatus provided with the excavation and stirring tool concerning this invention.

  The gist of the present invention is an excavation / stirring tool for performing ground improvement by kneading excavated soil and an improving material while excavating / stirring the ground, the excavation / stirring shaft extending in the vertical direction, and the above excavation / stirring Supported by the lower end of the shaft and excavating the ground, supported by the outer peripheral surface of the excavation and agitation shaft, driven agitation blade rotating integrally with the excavation and agitation shaft, and around the outer periphery of the excavation and agitation shaft An arc-shaped stirring blade straddling the outer peripheral surface of at least two or more boss portions loosely fitted in, and bulging outward to form an arc shape, the arc-shaped stirring blade being provided on the excavation / stirring shaft A drilling / stirring tool characterized in that the outermost floating stirring blade rotates in a floating state with respect to the rotation centerline of the arc-shaped stirring blade in an eccentric position with respect to the rotation centerline of the drilling / stirring shaft. It is in that.

  Specifically, the excavation / stirring tool according to the present invention is configured such that, in the excavation / stirring shaft, at least two or more free-fitting portions of the boss portions over which the arc-shaped stirring blades are strung are arranged on the rotation center line of the excavation / stirring shaft. There are at least two eccentric parts that are eccentric with respect to each other, and the central axis (eccentric axis) of each eccentric part is arranged on the same straight line to form the rotation center line of the arc stirring blade, and the rotation center line of the arc stirring blade is The position is eccentric with respect to the rotation center line of the excavation and agitation shaft.

  That is, the excavation / stirring tool according to the present invention has an eccentric shaft structure configured to decenter the rotation center line of the arc-shaped stirring blade with respect to the rotation center line of the drilling / stirring shaft, and the arc-shaped stirring blade is formed in the drilling hole. By making the engagement with the surrounding ground at least or without engagement, and making it vibrate in the excavation hole, the co-rotation phenomenon is surely prevented to improve excavation and agitation efficiency, and the construction speed It is intended to improve.

  As will be described in detail later, the eccentric shaft structure has at least two bosses straddling the arc-shaped stirring blades of the excavation / stirring shaft, and the excavation / stirring shaft has a predetermined amount of eccentricity in the loose fitting portion. And a structure having an eccentric inner ring (hereinafter simply referred to as an eccentric ring structure) and a middle portion of the excavation / stirring shaft bent radially outward with respect to the rotation center line of the excavation / stirring shaft, and protruded. And a structure in which an eccentric shaft portion having an eccentric amount of 1 is formed (hereinafter simply referred to as a shaft bending eccentric shaft structure).

  Here, examples of the shape of each agitating blade such as the excavating / stirring shaft, the driving agitating blade and the floating agitating blade supported by this, and the arrangement configuration of each agitating blade on the excavating / stirring shaft are as follows. Embodiments are possible. FIGS. 17-21 is explanatory drawing which shows an example of the shape of each stirring blade, such as the digging / stirring shaft 1, the drive stirring blade 3 and the floating stirring blade 6, and the arrangement configuration of each stirring blade on the digging / stirring shaft. is there.

  First, in the excavation / stirring tool A according to the present invention, the “arc-shaped” in the shape of the arc-shaped stirring blade among the stirring blades is other than the substantially arc-shaped shape having no corner as shown in FIGS. In addition, a substantially triangular arc shape having one corner, a substantially quadrangular arc shape having two corners, and a substantially polygonal shape having three or more corners are also included.

  In addition, the “arc shape” includes a blade shape in which a blade tip protrudes at a corner portion as shown in FIGS. 17A and 17B, and includes a corner portion that is chamfered in an R shape. It is.

  Each of the “arc-shaped” shapes is a portion that is supported with respect to the outer peripheral surface of the digging / stirring shaft 1 or the boss part loosely fitted around the outer periphery of the excavating / stirring shaft 1 in a side view. It also includes a shape that bulges upward or / and below the axial direction.

  Moreover, the shape of each stirring blade is not limited to the above-mentioned arc shape, For example, as shown in FIGS. 18-20, rod shape, plate shape, strip shape, H shape, T shape, L A letter shape is also included.

  In addition, the cross section of each stirring blade may be rectangular, rhombus, triangle, polygon, trapezoid, circle, ellipse, or the like.

  In addition, the “plate shape” of each agitating blade is a substantially horizontal plate shape with the wide plate surface oriented in the axial direction of the excavation / stirring shaft, and a substantially vertical plate shape with the plate surface oriented in the circumferential direction of the excavating / stirring shaft It may be, and is not limited in terms of plate thickness or shape.

  In addition, there may be a plurality of stirring blades, with an equiangular interval at the central angle as viewed in the axial direction of the excavation / stirring shaft, for example, 180 °, 120 °, 90 °, 60 ° intervals, etc. You may arrange | position radially at an angle.

  Further, the excavation / stirring shaft 1 may be configured to have a double shaft structure of an inner shaft 100 and an outer shaft 110 that are driven to rotate relative to each other as shown in FIG. 2 is an upper excavation blade 120 provided on the outer peripheral surface of the outer shaft 110, and a lower excavation blade provided on the outer peripheral surface of the exposed portion of the inner shaft 100 below the upper excavation blade 120 and formed to have a diameter less than the upper excavation blade diameter. It is good also as comprising with 130.

  Further, in the following description, “the rotation center line of the excavation / stirring shaft” is intended to be the rotation axis line when the excavation / stirring shaft rotates, and “the rotation centerline of the arc-shaped stirring blade” It is a rotation axis when the stirring blade rotates, and is an eccentric axis with respect to the excavation / stirring shaft, and is intended to be on the same axis as the rotation center line of the boss portion on which the arc-shaped stirring blade is supported.

[1. (Ground improvement device)
First, the structure of the ground improvement apparatus provided with the excavation and stirring tool concerning this invention is demonstrated. FIG. 22 shows a ground improvement device K provided with the excavation / stirring tool A according to the present invention. As shown in FIG. 22, the ground improvement device K is installed on the ground surface of the improved portion of the ground G.

  The ground improvement device K is provided in a self-propelled base machine main body 200 and is formed by extending in the vertical direction, a reader 210 extending in the vertical direction, a rotation driving unit 220 attached to the reader 210 so as to be movable up and down, The basic configuration includes the excavation / stirring shaft 1 attached to the lower end of the rotation driving unit 220 and the improvement material supply unit 230 that supplies the improvement material.

  The improvement material supply unit 230 disposed at the rear position of the base machine main body 200 is configured to supply the improvement material into the excavation hole, and is connected to the rotation drive unit 220 via the improvement material supply path 231. The improvement material supply path inside the excavation / stirring shaft 1 communicates with and communicates.

  The improvement material is a material that is kneaded with excavated soil to improve the ground, and solidifying materials, admixtures, additives, neutralizing agents, chemicals, chemical agents, etc. can be adopted according to the purpose of ground improvement. .

  The improvement material supplied from the improvement material supply unit 230 is discharged from the discharge port formed in the excavation / stirring tool A into the excavation hole via the improvement material supply path 231 in the excavation / stirring shaft 1 and excavated. -It is agitated with excavated soil by agitator A.

  The rotation drive unit 220 allows the reader 210 to move in the vertical direction via the suspension wire 221 by a drive rotation drum built in the rear part of the base machine body 200.

  The suspension wire 221 has one end connected to the drive rotary drum, and a midway part is wound around the pulley 222 provided on the rotation drive unit 220 via the topmost part of the reader 210, and the other end is wound on the upper end part of the reader 210. It is linked to.

  That is, the rotary drive force of the drive rotary drum is converted into the vertical lift drive force along the reader 210 so that the excavation / stirring shaft 1 moves up and down during penetration and extraction in ground improvement.

  A driving machine (not shown) is mounted inside the rotation driving unit 220, and the excavation / stirring shaft 1 is connected to the driving machine at the upper end thereof and is driven to rotate. In addition, the drive machine in the rotation drive part 220 should just provide a drive force as a rotational force of a digging / stirring shaft, and the digging / stirring shaft having the double shaft structure that is relatively driven as described above. The double drive machine corresponding to 1 may be used.

  The ground improvement device K configured as described above includes the excavation / stirring tool A, which is a main part that performs ground improvement by mixing the excavated soil and the improvement material while excavating and stirring the ground.

[2. Example 1]
Hereinafter, the structure of the excavation / stirring tool according to Example 1 of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing the configuration of a digging / stirring tool A1 according to the present embodiment, FIGS. 2 and 3 are schematic plan views showing the structure of an eccentric portion of a digging / stirring shaft, and FIG. 4 is a digging / stirring tool A1. FIG. 6 is a side view showing the configuration of the digging / stirring tool A1, and FIG. 7 is a plan view showing the rotation locus of the digging / stirring tool A1.

  As shown in FIG. 1, the excavation / stirring tool A according to the present embodiment includes a drilling / stirring shaft 1 extending in the vertical direction, and a drilling blade 2 supported on the lower end of the excavation / stirring shaft 1 and excavating the ground. A drive stirring blade 3 supported on the outer peripheral surface of the excavation / stirring shaft 1 and rotating integrally with the excavation / stirring shaft 1, and at least two boss portions 4 loosely fitted around the outer periphery of the excavation / stirring shaft 1. And an arcuate stirring blade 5 that is supported on the outer peripheral surface and bulges outward to form an arc shape.

  That is, the excavation / stirring tool A includes a plurality of stirring blades supporting at least one end with respect to the outer peripheral surface of the excavation / stirring shaft 1 or the outer peripheral surface of the boss part 4 loosely fitted around the outer periphery of the excavation / stirring shaft 1. The plurality of stirring blades includes a drive stirring blade 3 that rotates integrally with the excavation / stirring shaft 1 and a floating stirring blade 6 that rotates in a floating state with respect to the drilling / stirring shaft.

  Among the plurality of stirring blades, the outermost arc stirring blade 5 is a floating stirring blade 6, and the drive stirring blade 3 and the floating stirring blade 6 are alternately arranged at predetermined intervals from the arc stirring blade 5 to the inside. Has been.

  That is, the floating stirring blade 6 and the drive stirring blade 3 as a plurality of stirring blades are connected to the axially central portion C (two upper and lower bosses to which the base end of the arc stirring blade is connected) from the arc stirring blade 5 which is the floating stirring blade 6. The portions 4a and 4b are arranged in order with respect to the excavation / stirring shaft 1 at intervals along the outer shape of the respective stirring blades toward the center of the excavation / stirring shaft 1).

  More specifically, the floating stirring blade 6 and the drive stirring blade 3 are in the same phase around the excavation / stirring shaft 1, and are axially central portions of the blade main body portions to be described later in side view. The inner and outer blade layers are arranged in a concentric arrangement with respect to the drilling / stirring shaft 1 in a substantially ripple shape.

  The driving agitating blade 3 is a cantilever agitating blade 7 which is bent in the middle portion of the belt plate to form a letter H or a substantially L shape.

  The cantilever stirring blade 7 is formed so that the band plate shape is along the rotation center line and the plate surface is directed in a tangential direction with respect to the circumference of the rotation center line of the boss portion 4. Specifically, the cantilever stirring blade 7 includes a strip plate-like blade body portion 71 extending in the axial direction of the excavation / stirring shaft 1, and a blade support portion 72 extending from one end of the blade body portion 71 through a bent portion. ,have.

  The cantilever agitating blade 7 has the tip of the blade main body 71 directed upward in the axial direction of the excavation / stirring shaft 1 and is exposed between the two upper and lower boss portions 4a, 4b in the excavation / stirring shaft 1 1 is supported by connecting a blade support 72 to the outer peripheral surface.

  Of the two bosses 4 loosely fitted to the excavation / stirring shaft 1, the upper boss 4 a has a cantilever stirring as the floating stirring blade 6 located on the innermost side in the circumferential direction among the plurality of stirring blades. The blade 14 is supported by connecting the blade support 142 to the tip of the blade body 141 upside down from the tip of the blade body 71 of the cantilever stirring blade 7 as the drive stirring blade 3.

Arc-shaped stirring blade 5 is a strip arcuate idler stirring blade 6 positioned outermost circumferential direction among the plurality of agitating blades, along the strip shape in the rotational center line S1 of the excavation and stirring shaft 1 In addition, the plate surface is formed in a tangential direction with respect to the circumference around the rotation center line S2 of the boss portion 4.

  The arc-shaped stirring blade 5 extends from the blade body 51 to the at least two or more bosses 4 through the bent portion by forming a strip-shaped blade main body 51 having an arc-shaped outer shape of the arc-shaped stirring blade in a side view. And at least two blade support portions 52 connected to the boss portion 4.

  The wing body 51 is disposed in a stationary agitation zone for excavated / improved soil, functions as a soil resistance receiving portion, and functions as an engagement end that engages with the surrounding ground. The blade support part 52 is basically a part that bends and extends from both ends of the blade body part 51 and supports the arc-shaped stirring blade 5, but in addition to both ends of the blade body part 51, It can be extended according to the number of the boss portions 4.

  As shown in FIGS. 1 and 6 (a), the blade support portion 52 of the present embodiment has an upper blade support portion 52a and a lower blade as both ends of the arc stirring blade 5 so as to correspond to the upper and lower boss portions 4a and 4b. There are two side wing support portions 52b, and each extends from both end edges of the wing body portion 51 toward the boss portions 4a and 4b.

  Further, in the excavation / stirring shaft 1, as shown in FIGS. 1 and 2, the loose fitting portions of at least two or more boss portions 4 across which the arc-shaped stirring blades 5 are straddled are the rotation center line of the excavation / stirring shaft 1. The central axis (eccentricity) of the eccentric part is arranged on the same straight line to form the rotation center line of the arc-shaped stirring blade 5, and the rotation center line S2 of the arc-shaped stirring blade 5 is excavated and stirred. The position is eccentric with respect to the rotation center line S1 of the shaft 1.

  Specifically, the eccentric shaft structure is an “eccentric ring structure”, and a predetermined eccentricity with respect to the excavation / stirring shaft 1 at a predetermined position in the axial direction of the excavation / stirring shaft 1 as shown in FIGS. And at least two or more eccentric inner rings 10 that rotate integrally with the excavation / stirring shaft 1 and can rotate relative to the eccentric inner ring 10 around the outer periphery of the eccentric inner ring 10 and function as an eccentric outer ring. It is constructed by two or more boss parts 4 and an arc stirring blade 5 that straddles the outer peripheral surface of at least two or more boss parts 4 and functions as a continuous rod.

  The eccentric inner ring 10 is an eccentric member that causes an eccentric motion when the excavation / stirring shaft 1 is rotationally driven as a vibration source of the arc-shaped stirring blade 5, and is a rotation center line S3 of the arc-shaped stirring blade 5, that is, at least two or more. The axis of the excavation / stirring shaft 1 according to the number of the blade support portions 52 (number of the boss portions) of the arc-shaped stirring blade 5 so that the rotation center line S2 (rotating shaft) of each boss portion 4 is on the same axis. It is eccentrically arranged at a predetermined interval in the direction.

  The shape of the eccentric inner ring 10 is not particularly limited as long as it is a shape having a contact that can be slidably contacted with the outer peripheral surface having the maximum outer diameter L with respect to the inner peripheral surface of the boss portion 4. It may be a shape or an asymmetric shape.

  Specifically, as shown in FIG. 3A, the eccentric inner ring 10 has a maximum outer diameter L when viewed in the axial direction, and a rotation center line S 1 of the excavation / stirring shaft 1 and a center axis S 4 in the shape of the eccentric inner ring 10. The outer diameter at the position of the straight line passing through the (eccentric axis) may be set so that the maximum outer diameter L is substantially the same as the inner diameter l of the boss portion 4.

  In other words, the eccentric inner ring 10 is on one side of the straight line L1 passing through the central axis S4 of the eccentric inner ring 10 and the rotation center line S1 of the excavation / stirring shaft 1 as viewed in the axial direction with respect to the inner peripheral surface of the boss portion 4. The eccentric inner ring 10 is in contact with the digging / stirring shaft 1 on the other side of the straight line L1.

  Here, on the straight line L1, the distance T1 from the rotation center S1 of the excavation / stirring shaft 1 to the contact position P1 of the eccentric inner ring 10 with respect to the inner peripheral surface of the boss portion 4 is from the rotation center S1 of the excavation / stirring shaft 1. It is longer than the distance T2 to the contact position P2 of the excavation / stirring shaft 1 with respect to the inner peripheral surface of the boss part 4.

  Therefore, when the excavation / stirring shaft 1 rotates, the contact position P2 of the eccentric inner ring 10 draws a circular trajectory having a radius T2 with the rotation center S1 of the excavation / stirring shaft 1 as the center.

  As the shape of the eccentric inner ring 10, as shown in FIGS. 3 (b) to 3 (e), for example, an elliptical shape, a rectangular protrusion shape, a triangular protrusion shape, and a multi-protrusion shape can be used in the axial view. it can. In this embodiment, as shown in FIG. 3A, the shape is circular (cylindrical) as viewed in the axial direction.

  In the at least two or more eccentric inner rings 10, each of the eccentric inner rings 10 is formed to have the same major radius around the central axis S4 in each shape, and the predetermined position in the axial direction of the excavation / stirring shaft 1 Thus, they are provided at predetermined positions in the axial direction of the excavation / stirring shaft 1 with a predetermined radial direction (hereinafter referred to as an eccentric direction) centered on the rotation center line S1 of the excavation / stirring shaft 1 and the same eccentric amount. .

  In addition, the central axis S4 in the shape of each eccentric inner ring 10 is arranged on the same straight line to form the rotation center line S3 of the arc-shaped stirring blade 5, and the rotation center line S3 of the arc-shaped stirring blade 5 is It is decentered parallel to the rotation center line S1.

  The eccentric inner ring 10 of this embodiment is an eccentric inner ring located at the uppermost part (hereinafter referred to as the uppermost eccentric inner ring 10a) and an eccentric inner ring located at the lowermost part (hereinafter referred to as the lowermost eccentric inner ring 10b). These are of the same shape and size, and are provided at predetermined positions in the axial direction of the excavating / stirring shaft 1 with the same eccentric direction and the same eccentric amount.

  When three or more eccentric inner rings 10 are formed, that is, when another eccentric inner ring 10 is formed between the uppermost eccentric inner ring 10a and the lowermost eccentric inner ring 10b, the other eccentric inner rings 10 are It goes without saying that the excavation / stirring shaft 1 is provided so that its central axis is arranged on the same straight line as the central axis in the shapes of the uppermost eccentric inner ring 10 and the lowermost eccentric inner ring 10b.

  The rotation center line S3 of the arc-shaped agitating blade 5 straddling the boss portion 4 is boss portion by loosely fitting the corresponding boss portion 4 around the outer periphery of each eccentric inner ring 10 as described above. 4, the central axis S 4 in each eccentric inner ring 10 shape and the rotation center line S 2 of the corresponding boss portion 4 coincide with each other.

  With such a configuration, an eccentric shaft structure for straddling an arc-shaped stirring blade to be oscillated at a desired position on the drilling / stirring shaft 1 without bending the drilling / stirring shaft 1 as a main shaft body. Can be constructed easily and freely, and the strength corresponding to the vertical load on the excavating and agitating shaft 1 from the excavating and agitating soil during the penetrating and extracting operations can be maintained.

  Returning to the explanation of the arc-shaped stirring blade 5, as shown in FIGS. 1 and 3, the arc-shaped stirring blade 5 has a maximum improved diameter M by the arc-shaped stirring blade 5 in a state of being straddled by at least two boss portions. The excavation blade diameter (indicated by a two-dot chain line extending outwardly about the rotation center line S1 of the excavation / stirring shaft 1 in FIG. 4) is set to be equal to or less than the excavation blade diameter.

  In other words, the sum of the arc-shaped stirring blade radius D of the arc-shaped stirring blade 5 and the eccentric amount d of the rotation center line S3 of the arc-shaped stirring blade 5 with respect to the rotation center line of the drilling / stirring shaft is the drilling blade of the drilling blade 2 Arc-shaped stirring blades 5 are formed so as to have a radius R or less.

  The arc-shaped stirring blade radius D is intended to mean the rotation radius of the arc-shaped stirring blade 5 including the blades attached to the arc-shaped stirring blade body (hereinafter simply referred to as a circumferential radius). In the case where auxiliary blades are provided outside the blade main body portion 51 and blade support portion 52, the radius is from the rotation center line of the arc stirring blade to the auxiliary blade tip located on the outermost peripheral side.

  Further, the arc-shaped stirring blade 5 is in the form of a ribbon plate, and the width of the blade-shaped surface in the side view is a member width, the width of the blade-shaped surface in the axial direction is a member thickness, and the member thickness is equal to or less than the member width. It is formed to become.

  Specifically, the blade main body 51 and the blade support portion 52 of the arc-shaped stirring blade 5 are perpendicular to the radial direction of the rotation center line of the boss portion when viewed in the axial direction of the rotation center line S2 of the boss portion 4, that is, A tangential direction with respect to the circumference around the rotation center line S2 of the boss portion 4 is defined as a plate thickness direction.

  The excavation / stirring tool A1 configured as described above operates as follows. That is, as shown in FIG. 5, the arc-shaped stirring blade 5 has the blade body 51 disposed in the stationary stirring region in the excavation hole, receives a rotational resistance force from the excavation / improvement soil, and rotates the excavation / stirring shaft 1. It becomes a stationary state against.

  In addition, since the upper and lower boss portions 4a and 4b are transmitted with reaction force against the rotational force of the excavation / stirring shaft 1 via the arc-shaped stirring blade 5, they become immobile, so that the inner cantilever stirring supported by the upper boss portion 4a. The wing 14 is also immovable.

  When the excavation / stirring shaft 1 is driven and rotated in such a state, the eccentric inner rings 10a, 10b inside the boss portions 4a, 4b rotate integrally with the excavation / stirring shaft 1 to view the excavation / stirring shaft 1 in the axial direction. An eccentric motion that rotates around a rotation center line S1 so as to draw a circular locus corresponding to the eccentric amount d is performed.

  Since the two upper and lower eccentric inner rings 10a and 10b have the same shape and the same size and are formed with the same eccentric amount in the same radial direction with respect to the excavation / stirring shaft 1, the eccentric movements of the eccentric inner rings 10a and 10b coincide. .

  Such eccentric motion of the eccentric inner rings 10a, 10b is eccentric about the rotation center line S1 of the excavation / stirring shaft 1 as shown in FIGS. 6 (b) and 7 (a) to 7 (e). The rotational center S4 of the inner rings 10a and 10b is a rotational motion that rotates so as to draw a circular locus having a radius of eccentricity d.

  That is, as the excavation / stirring shaft 1 rotates, the contact position P2 between the eccentric inner ring 10 and the boss portion 4 is a radius around the rotation center S1 of the excavation / stirring shaft 1 as shown in FIG. The eccentric inner ring 10 slides on the inner peripheral surface of the boss portion 4 at the contact position P2 by drawing a trajectory of the circumference of T2.

  And since the boss | hub parts 4a and 4b which are a stationary state in the rotation direction via the arc-shaped stirring blade 5 are rotatably fitted with respect to the eccentric inner ring | wheels 10a and 10b, FIG. 7 (a)-FIG. As shown in (e), the eccentric inner rings 10a and 10b are slid in response to the rotational movement of the eccentric inner rings 10a and 10b, and are reciprocally oscillated to move in the radial direction by the amount of the eccentricity.

  In other words, the bosses 4a and 4b are guided by the excavation / improved soil in the stationary agitation zone existing near the blade end surface (plate surface of the blade body 51) via the arc stirring blade 5 functioning as a connecting rod. The eccentric motion of the eccentric inner rings 10a, 10b is converted into a reciprocating rocking motion.

  As a result, the arc-shaped stirring blade 5 and the cantilever stirring blade 14 as the floating stirring blade 6 are maintained in a fixed posture with respect to the rotation direction of the excavation / stirring shaft 1 as shown in FIG. In conjunction with the parts 4a and 4b, the reciprocating rocking motion is performed so as to perform a reciprocating rocking motion that draws a circular locus while moving in the radial direction from the rotation center line of the excavation / stirring shaft 1 in the radial direction in a side view.

  That is, the arc-shaped stirring blade 5 and the cantilever stirring blade 14 always maintain a constant amplitude at the rotation center line S1 of the excavation / stirring shaft 1 in the axial direction according to the amount of eccentricity as the excavation / stirring shaft 1 is driven and rotated. The vibration is caused by circular motion, and the vibration stress is transmitted to the excavated / improved soil near the wing, so that the "soil adhesion suppression action" and the "tightening prevention action" occur on the outermost side and the innermost side.

  In particular, the blade body 51 constituting the arc stirring blade transmits the same vibration stress to the excavation / improved soil in the stationary agitating region, thereby realizing the forced vibration agitation of the excavated / improved soil in the stationary state.

  More specifically, when the blade body 51 performs a substantially circular motion corresponding to the amount of eccentricity (circular motion trajectory at both ends of the arc-shaped stirring blade in FIG. 5) in the axial direction, excavation / improvement in a stationary state. The soil can be forcibly rotated and stirred, and a new stirring effect that enables “vertical shear stirring” accompanied by the rotational motion of the blade body 51, which is not presently improved, is enabled.

  That is, the arc-shaped stirring blade 5 functions as a co-rotation preventing blade that becomes stationary in the rotation direction of the excavation / stirring shaft by receiving resistance from the excavation / improved soil in the stationary stirring region at the blade main body 51. However, it is possible to function as a vertical shear rotating stirring blade that locally and partially rotates and stirs excavated and improved soil in a stationary stirring region by vibrating vibration according to the amount of eccentricity.

  As a result, the excavation / stirring tool A1 includes the cantilever agitating blade 7 as the driving agitating blade 3 that is driven to rotate, and the arc-shaped agitating blade 5 and the cantilever agitating blade 14 that vibrate while maintaining the immovable posture as the floating agitating blade 6. The “shear line” is surely generated between them and the “co-rotation preventing effect” is made solid, and the stirring effect of uniform stirring throughout the improved body is improved.

  Further, since the arc-shaped stirring blade 5 is supported by the excavation / stirring shaft 1 via the bosses 4a and 4b so that the maximum improved diameter is equal to or less than the drilling blade diameter, the reciprocating swinging motion range, that is, the maximum vibration is achieved. The range can be accommodated within the diameter of the excavation hole, and the blade main body 51 corresponding to the blade tip portion of the arc-shaped stirring blade 5 is not engaged with the surrounding ground and is not affected by the frictional resistance from the surrounding ground.

  Furthermore, the arc-shaped agitating blade 5 is in the form of a ribbon, and the width of the blade shape surface in the side view is defined as the member width, the width of the blade shape surface in the axial direction is defined as the member thickness, and the member thickness is equal to or less than the member width. As a result, the blade area with respect to the improved area of the arc stirring blade 5 in the axial direction is reduced, and the passage resistance of the excavation / improvement soil and the soil adhesion of the excavation / improvement soil during the intrusion / pulling operation are reduced. It is possible to reduce as much as possible.

  Further, as a result of the vibration force of the arc stirring blade 5 being transmitted as reaction force to the excavation / stirring shaft 1 via at least two or more boss portions 4, the drilling blade 2 and the drive stirring blade 3 can be vibrated. The "adhesion suppression action" and the "tightening prevention action" are promoted and the excavation speed is improved. The relative agitation effect due to the alternate arrangement of the drive agitation blades 3 and the idler agitation blades 6 is combined to dramatically increase the construction speed. Can be improved.

[Example 2]
Next, a second embodiment of the excavation / stirring tool according to the present invention will be described. FIG. 8 is a side view showing the configuration of the excavation / stirring tool A2. In addition, below, about the structure similar to the digging and stirring tool A1 concerning Example 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The excavation / stirring tool A2 according to the present embodiment has substantially the same configuration as the excavation / stirring tool A1, and the rotation center line S3 of the arc-shaped stirring blade 5 is connected to the excavation / stirring shaft 1 as shown in FIG. A structure that is eccentric in parallel to the rotation center line S1 and that can vibrate when the arc-shaped stirring blade 5 reciprocally swings in the radial direction about the rotation center line S1 of the excavation / stirring shaft 1 by the amount of eccentricity. However, the configuration is different in that the eccentric shaft structure is an “axial bending eccentric shaft structure”.

  That is, the excavation / stirring tool A2 is bent at a part of the excavation / stirring shaft 1 outward in the radial direction of the excavation / stirring shaft 1 and extends along the axial direction of the excavation / stirring shaft 1. The rotation center line S5 of the eccentric shaft portion 11 is set as the rotation center line S3 of the arc-shaped stirring blade 5, and the rotation center line S3 of the arc-shaped stirring blade 5 is eccentric with respect to the rotation center line S1 of the excavation / stirring shaft 1 Placed in position.

  Specifically, the digging / stirring shaft 1 includes a digging / stirring shaft main body 12 as a main shaft that rotates on the same axis as the rotation center line S1 of the digging / stirring shaft 1 as shown in FIG. The upper and lower eccentric bent portions 13a and 13b formed by bending the excavation / stirring shaft 1 so as to have the same peripheral radius in a predetermined eccentric direction around the excavation / stirring shaft main body portion 12, and the eccentric bent portion 13a 13b, an eccentric shaft portion 11 formed by extending substantially parallel to the excavation / stirring shaft main body portion 12, and at least two or more loosely fitted around the outer periphery in the axial direction of the eccentric shaft portion 11 The boss portions 4a and 4b and the arc-shaped stirring blade 5 straddling the at least two or more boss portions 4a and 4b constitute an “axially bent eccentric shaft structure”.

  The amount of eccentricity of the eccentric shaft portion 11 is the circumferential radius of the two upper and lower eccentric bent portions 13a and 13b (the distance between the virtual straight line orthogonal to the rotation center line S1 of the excavation / stirring shaft 1 and the tip position of the eccentric bent portions 13a and 13b). In this embodiment, the upper and lower eccentric bends 13a and 13b have the same peripheral radius.

  With such a configuration, the eccentric shaft portion 11 rotates integrally with the excavation / stirring shaft 1 in accordance with the rotation of the excavation / stirring shaft 1 and is eccentric about the rotation center line of the excavation / stirring shaft 1 as in the first embodiment. Eccentric motion is performed to draw a circular trajectory with the amount as the radius.

  That is, the eccentric shaft 11 is reciprocally oscillated so that the upper and lower bosses 4 a and 4 b are guided by excavation and improved soil in the stationary agitation zone existing near the blade body 51 via the arc-shaped stirring blade 5. It is possible to switch to exercise.

  Further, the arc-shaped stirring blade 5 and the cantilever stirring blade 14 as the floating stirring blade 6 are maintained in the stationary posture state with respect to the rotation direction of the excavation / stirring shaft 1 in the axial direction as shown in FIG. In conjunction with the boss portions 4a and 4b, it is possible to perform a reciprocating rocking motion that draws a circular locus while moving in the radial direction from the rotation center line of the excavation / stirring shaft 1 by an amount of eccentricity.

  Further, in the eccentric shaft portion 11, a cantilever stirring blade 7 as a drive stirring blade 3 is supported between the upper and lower boss portions 4 a and 4 b on which the arc stirring blade 5 is straddled.

  In other words, the floating stirring blades 6 and the driving stirring blades 3 as a plurality of stirring blades are connected from the arc stirring blade 5 which is the floating stirring blade 6 to the axial center C (the base end of the arc stirring blade 2 is connected 2). Are arranged in order with respect to the eccentric shaft portion 11 of the excavation / stirring shaft 1 at intervals along the outer shape of the respective stirring blades toward the upper and lower boss portions 4a, 4b (center portion of the excavation / stirring shaft 1). Has been.

  More specifically, the arc stirring blade 5 and the drive stirring blade 3 are substantially in phase with each other around the eccentric shaft portion 11 of the excavation / stirring shaft 1, and each blade body portion 51 in a side view. The inner and outer blade layers are arranged in a substantially ripple pattern with respect to the excavation / stirring shaft 1 so as to have a substantially concentric arrangement with the central portion in the axial direction.

  With such a configuration, as shown in FIG. 4, the arc-shaped stirring blade 5 receives resistance from the excavation / improvement soil in the stationary stirring region at the blade main body 51, so that the rotation direction of the excavation / stirring shaft is reduced. While functioning as a co-rotation prevention blade that becomes stationary, it functions as a vertical shear rotating stirring blade that locally and partially rotates and stirs excavated and improved soil in a stationary stirring zone by vibrated vibration according to the amount of eccentricity.

  Further, as shown in FIG. 8B, not only the arc-shaped stirring blade 5 and the cantilever stirring blade 14 as the floating stirring blade 6 vibrate but also the cantilever stirring as the eccentric shaft portion 11 and the drive stirring blade 3. The blade 7 will perform an eccentric motion in accordance with the amount of eccentricity in the excavation hole, further improving the above-mentioned relative stirring effect and making the “soil adhesion inhibiting action” to each stirring blade steady and uniform throughout the improved body Improve the stirring effect of proper stirring.

  In the present embodiment, one eccentric shaft portion 11 is formed on the excavation / stirring shaft 1, but at least two or more bosses that are loosely fitted on the eccentric shaft portion 11 and over which the arc-shaped stirring blade 5 is straddled. If the rotation center line S2 of the part 4 is on the same line, the number is not limited.

  That is, a plurality of eccentric shaft portions 11 having the same direction and the same amount of eccentricity are provided only in portions corresponding to at least two or more individual boss portions 4 on which the arc-shaped stirring blades 5 are straddled in the excavation / stirring shaft 1. Of course, the drive stirring blade 3 inside the arc-shaped stirring blade 5 can be supported by the excavation / stirring shaft main body 12 while being bent.

Example 3
Next, the excavation / stirring tool A3 according to Example 3 of the present invention will be described. FIG. 9 is a side view showing the configuration of the excavation / stirring tool A3, and FIG. 10 is a schematic explanatory view showing the structure of the eccentric portion of the excavation / stirring shaft.

  The excavation / stirring tool A3 according to this example has substantially the same configuration as the excavation / stirring tool A1, and the eccentric shaft structure is an “eccentric ring structure”. The configuration is different in that the rotation center line of the blade is inclined with respect to the rotation center line of the excavation / stirring shaft.

  That is, at least two or more eccentric inner rings 30a and 30b that rotate together with the excavation / stirring shaft 1 at a predetermined position in the axial direction of the excavation / stirring shaft 1 rotate the excavation / stirring shaft 1 as shown in FIG. An eccentric inner ring 30a having a maximum eccentricity with a different amount of eccentricity in a predetermined eccentric direction around the center line and an eccentric inner ring 30b having a minimum eccentricity are provided, and the central axis S4 in the shape of each of the eccentric inner rings 30a, 30b is the same. The rotation center line S3 of the arc-shaped stirring blade 5 is formed on a straight line, and the rotation center line S3 of the arc-shaped stirring blade 5 is formed so as to be inclined with respect to the rotation center line S1 of the excavation / stirring shaft 1.

  In other words, at least two or more eccentric inner rings 30a and 30b formed at predetermined positions in the axial direction of the excavation / stirring shaft 1 are formed by the excavation / stirring shaft as shown in FIGS. 10 (a) and 10 (b). 1 has a similar shape with gradually different maximum outer diameters along the axial direction of 1, and is gradually eccentric along the axial direction of the drilling / stirring shaft 1 in a predetermined eccentric direction around the rotation center line S1 of the drilling / stirring shaft 1. The central axes S4 in the shapes of the eccentric inner rings 30a and 30b are arranged on the same straight line and are inclined with respect to the rotational center line S1 of the excavation / stirring shaft 1 in different amounts.

  The two or more eccentric inner rings 10 according to the present embodiment have a cylindrical shape in which the uppermost eccentric inner ring 30 has a larger maximum outer diameter than the lowermost eccentric inner ring 30b in a predetermined eccentric direction with respect to the excavation / stirring shaft 1. The eccentric inner ring 30a is an eccentric inner ring having the maximum eccentricity, the lowermost eccentric inner ring 30b is an eccentric inner ring having the minimum eccentricity, and the central axis S4 in the cylindrical shape of the uppermost eccentric inner ring 30a and the lowermost eccentric inner ring 30b is the same. It is arranged on a straight line.

  The corresponding uppermost boss 4a and lowermost boss 4b are rotatably fitted around the outer periphery of the uppermost eccentric inner ring 30a and the lowermost eccentric inner ring 30b, respectively. An arc stirring blade 5 is straddled.

  In other words, the rotation center line S3 of the arc-shaped agitating blade 5 coincides with the center axis S4 of the uppermost eccentric inner ring 30a and the lowermost eccentric inner ring 30b via the boss portions 4a and 4b, as shown in FIG. As shown, the excavation / stirring shaft 1 is inclined with respect to the rotation center line S1.

  With such a configuration, when the excavation / stirring shaft 1 is driven to rotate, the eccentric inner rings 30a, 30b inside the boss portions 4a, 4b rotate integrally with the excavation / stirring shaft 1 to rotate the rotation center line of the excavation / stirring shaft 1 Eccentric motion is performed around S1 so as to draw an elliptical locus in side view and axial view according to the amount of tilt eccentricity.

  That is, as the excavation / stirring shaft 1 is driven to rotate, the arc-shaped stirring blade 5 that is stationary in the rotation direction vibrates in the left-right inclined direction in a side view as shown in FIG. The "vertical shear rotating stirring function" forcibly stirs excavated and improved soil in the static stir zone near the arc-shaped stirring blades, and transmits the vibration to the excavated and improved soil to prevent "soil adhesion" and "tightening prevention". ”Is promoted, and the“ co-rotation prevention effect ”can be surely produced.

Example 4
Next, an excavation / stirring tool according to Embodiment 4 of the present invention will be described. FIG. 11 is a side view showing the configuration of the excavation / stirring tool A4.

  The excavation / stirring tool A4 according to this example has substantially the same configuration as that of the excavation / stirring tool A2, and the eccentric shaft structure is the “axial bending eccentric shaft structure”. As in the excavation / stirring tool A3 according to the third embodiment, the configuration is different in that the rotation center line S3 of the arc-shaped stirring blade 5 is inclined with respect to the rotation center line S1 of the excavation / stirring shaft 1. .

  In other words, the eccentric shaft portion formed by bending at two locations in the middle of the excavation / stirring shaft 1 toward the outer side in the radial direction around the excavation / stirring shaft 1 is bent as shown in FIG. The portions are inclined eccentric shaft portions 21 having different circumferential radii in the portion, the rotation center line S5 of the inclined eccentric shaft portion 21 is formed as the rotation center line S3 of the arc-shaped stirring blade 5, and the rotation center line S3 of the arc-shaped stirring blade 5 is formed. The excavation / stirring shaft 1 is eccentric with respect to the rotation center line S1.

  Specifically, in the above-described “shaft bending eccentric shaft structure”, the two upper and lower eccentric bending portions 23a and 23b are arranged in a predetermined eccentric direction with respect to the rotation center line S1 of the excavation / stirring shaft 1 and to each other. The digging / stirring shaft 1 is bent outwardly so as to have different peripheral radii.

  That is, the two upper and lower eccentric bent portions 23a and 23b formed at a predetermined interval along the axial direction in the excavation / stirring shaft 1 have a circumferential radius of one eccentric bent portion 23a and a circumference of the other eccentric bent portion 23b. Unlike the radius, an eccentric bent portion 23a having a maximum peripheral radius and an eccentric bent portion 23b having a minimum peripheral radius are used.

  By forming the eccentric shaft portion 21 between the distal ends of the eccentric bending portions 23a and 23b, the rotation center line S5 of the eccentric shaft portion 11 becomes the rotation center line of the excavation / stirring shaft 1 as shown in FIG. Inclined with respect to S1.

  Further, around the outer periphery of the eccentric shaft portion 21, at least two or more boss portions 4a and 4b are freely loosely fitted, and at least two or more boss portions 4a and 4b are straddled with an arc stirring blade 5. ing.

  With this configuration, as in the third embodiment, as shown in FIG. 11 (b), the arc-shaped stirring blade 5 can be vibrated in the left-right tilt direction in side view as the excavation / stirring shaft 1 is driven and rotated. In addition, the “vertical shear rotary stirring function” of the arc stirring blades forcibly stirs the excavated and improved soil in the stationary stirring zone near the arc stirring blades, and promotes “soil adhesion suppression action” and “tightening prevention action”. Therefore, the “co-rotation prevention effect” can be surely produced.

Example 5
Next, the excavation / stirring tool A5 according to Example 5 of the present invention will be described. FIG. 12 is a side view showing the configuration of the excavation / stirring tool A5, and FIG. 13 is a schematic explanatory view showing the structure of the eccentric portion of the excavation / stirring shaft.

  The excavation / stirring tool A5 according to the present embodiment has substantially the same configuration as the excavation / stirring tool A3, and the eccentric shaft structure is an “eccentric ring structure” that is inclined and eccentric. The rotation center line S3 of the arc-shaped stirring blade 5 is the uppermost and lowermost of the at least two boss portions 4 over which the arc-shaped stirring blade 5 straddles the rotation center line S1 of the excavation / stirring shaft 1. The configurations are different in that they are inclined so as to cross each other.

  That is, among at least two or more eccentric inner rings 10a, 10b that are provided at predetermined positions in the axial direction of the excavation / stirring shaft 1 and rotate integrally with the excavation / stirring shaft 1, FIG. 12 (a) and FIG. Thus, the uppermost eccentric inner ring 10a and the lowermost eccentric inner ring 10b are formed such that their eccentric directions are opposite to each other via the excavation / stirring shaft 1 with respect to the rotation center line S1 of the excavation / stirring shaft 1. doing.

  Further, the central axis S4 in the shape of each of the eccentric inner rings 10a and 10b is on the same straight line to form the rotation center line S3 of the arc-shaped stirring blade 5, and the rotation center line S3 of the arc-shaped stirring blade 5 is between the eccentric inner rings 10a and 10b. The excavation / stirring shaft 1 is inclined so as to intersect the rotation center line S1.

  The uppermost eccentric inner ring 10a and the lowermost eccentric inner ring 10b according to the present embodiment have the same shape and the same size, and the eccentric directions of the uppermost eccentric inner ring 10a and the lowermost eccentric inner ring 10b are 180.degree. In addition, the excavation / stirring shaft 1 is formed at a predetermined position in the axial direction so as to have the same eccentric amount.

  The uppermost eccentric inner ring 10a and the lowermost eccentric inner ring 10b are the outermost parts that are rotatably fitted on the uppermost eccentric inner ring 10a and the lowermost eccentric inner ring 10b of the rotation center line S1 of the excavation / stirring shaft 1, respectively. At the center of the rotation center line S1 of the excavation / stirring shaft 1 between the boss part 4a and the lowermost boss part 4b, the rotation center line S3 of the arc stirring blade 5 is eccentric so as to intersect.

  With this configuration, when the excavation / stirring shaft 1 is driven to rotate, the eccentric inner rings 10a, 10b inside the boss portions 4a, 4b rotate integrally with the excavation / stirring shaft 1, and the rotation center line S1 of the excavation / stirring shaft 1 is rotated. The tilt eccentric motion is performed so as to draw an elliptical locus corresponding to the tilt eccentric amount in a side view and an axial view.

  That is, the arc-shaped stirring blade 5 that is stationary in the rotation direction in accordance with the driving rotation of the excavation / stirring shaft 1 is substantially horizontally and vertically about the excavation / stirring shaft 1 in a side view as shown in FIG. Excited and vibrated so as to perform reciprocating rocking motion, and the `` vertical shear rotary stirring function '' of the arc stirring blades forcibly stirs the excavated and improved soil in the stationary stirring area near the arc stirring blades, and excavates and improves By transmitting vibrations to the soil, the “soil adhesion inhibiting effect” and the “tightening preventing effect” are promoted, and the “corotation preventing effect” can be reliably generated.

Example 6
Next, an excavation / stirring tool A6 according to Example 6 of the present invention will be described. FIG. 14 is a side view showing the configuration of the excavation / stirring tool A6.

  The excavation / stirring tool A6 according to the present embodiment has substantially the same configuration as the excavation / stirring tool A4, and the eccentric shaft structure is an “axially bent eccentric shaft structure” in which the eccentric shaft is eccentric, but the “shaft bending eccentricity” is the same. In the “shaft structure”, as in the fifth embodiment, the rotation center line of the arc-shaped stirring blade is the outermost of the at least two boss portions supported by the arc-shaped stirring blade with respect to the rotation center line of the excavation / stirring shaft. The configuration is different in that the upper and lower bosses are inclined so as to cross each other.

  That is, the inclined eccentric shaft portions bent at two locations in the middle portion of the excavation / stirring shaft 1 from the excavation / stirring shaft 1 toward the outer side in the radial direction are mutually connected at a predetermined peripheral radius at the bent portion. The eccentric direction is formed in the reverse direction via the excavation / stirring shaft 1, the rotation center line S 5 of the inclined eccentric shaft portion 21 is formed as the rotation center line S 3 of the arc-shaped stirring blade 5, and the rotation center of the arc-shaped stirring blade 5 is formed. The line S3 is decentered by intersecting with the rotation center line S1 of the excavation / stirring shaft 1.

  Specifically, the two upper and lower eccentric bent portions 23a and 23b are centered on the rotation center line of the excavation / stirring shaft main body 12, and the peripheral radius of one eccentric bent portion 23a is set to the peripheral radius of the other eccentric bent portion 23b. The eccentric direction of one eccentric bent portion 23a is opposite to the eccentric direction of the other eccentric bent portion 23b.

  Similarly to the fifth embodiment, the two upper and lower eccentric bent portions 23a and 23b are connected to the rotation center line S1 of the excavation / stirring shaft 1 between the uppermost boss portion 4a and the lowermost boss portion 4b. At the center, the rotation center line S1 of the arc-shaped stirring blade 5 is eccentric so as to intersect the rotation center line S1 of the excavation / stirring shaft 1.

  With this configuration, as in the fifth embodiment, as the excavation / stirring shaft 1 is driven and rotated, the arc-shaped stirring blade 5 remains in a stationary posture with respect to the rotational direction, and is viewed from the side and in the axial direction. Excavation / improvement in the stationary agitation zone near the arc stirring blade by the "vertical shear rotation stirring function" of the arc stirring blade. As well as forcibly agitating the soil, the transmission of vibration to the excavated and improved soil promotes the "soil adhesion suppression action" and the "tightening prevention action", enabling the "co-rotation prevention effect" to occur reliably. Yes.

Example 7
Next, an excavation / stirring tool A7 according to Example 7 of the present invention will be described. FIG. 15 is a side view showing the configuration of the excavation / stirring tool A7.

  The excavation / stirring tool A7 according to the present embodiment has substantially the same configuration as the excavation / stirring tool A1, and the eccentric shaft structure is an “eccentric ring structure” in which the eccentric shaft is eccentric, but at least two or more boss portions The configuration is different in that the arc-shaped agitating blades supported by the shaft are twisted or inclined with respect to the rotation center line of the arc-shaped agitating blade.

  That is, as shown in FIG. 15, the arc-shaped stirring blade 8 has a band plate-shaped blade main body portion 81 and a blade support portion 82 that form an arc-shaped outer shape of the arc-shaped stirring blade in a side view, and the blade main body portion 81 and the blade support portion The plate surface of the portion 82 is formed as an inclined surface that is inclined with respect to the vertical direction, and is configured to rotate by the soil resistance received by the inclined surface as the excavating / stirring tool A7 penetrates and withdraws.

  The arc-shaped stirring blade 8 having such a shape is straddled over at least two or more boss portions 4a and 4b loosely fitted to at least two or more eccentric inner rings 10a and 10b on the excavation / stirring shaft 1. Achieving complex relative rotational agitation with the blade 8 and the drive agitating blade 3, and also causing the arc-shaped agitating blade 8 to vibrate to cause "soil adhesion inhibiting action" and "tightening preventing action" ”And the“ vertical shear rotary stirring function ”of the arc-shaped stirring blade 8 can ensure good kneadability of the excavated and improved soil.

  Of course, such an arcuate stirring blade 8 having an inclined shape can be applied as a configuration of a drilling / stirring tool having the various eccentric shaft structures of the above-described second to sixth embodiments.

Example 8
Next, an excavation / stirring tool A8 according to Example 8 of the present invention will be described. FIG. 16 is a side view showing the configuration of the excavation / stirring tool A8.

  The excavation / stirring tool A8 according to the present embodiment has substantially the same configuration as the excavation / stirring tool A1, and the eccentric shaft structure is an “eccentric ring structure” in which the eccentric shaft is eccentric, but at least two or more boss portions are provided. The arc-shaped agitating blades supported by the above are different from each other in that the maximum improved diameter of the arc-shaped agitating blade is formed to be larger than the excavating blade diameter.

  In other words, as shown in FIG. 16 (a), the arc stirring blade 9 is excavated with the arc stirring blade diameter D of the arc stirring blade 9 shown in FIG. 4 so as to engage the blade body 91 with the surrounding ground. The sum of the eccentric amount d of the rotation center line S3 of the arc-shaped stirring blade 9 with respect to the rotation center line S1 of the stirring shaft 1 is formed to be larger than the drilling blade diameter R of the drilling blade 2. That is, the wing body portion 91 functions as an engagement end portion having the plate width as the engagement depth along the longitudinal direction of the strip.

  Further, as shown in FIG. 16B, the arc stirring blade 9 has an engagement auxiliary blade 92 for engaging with the surrounding ground at a predetermined position on the outer edge of the band plate of the blade body 91. It is good also as extending toward the direction.

  Further, the arc stirring blade 9 and the engagement auxiliary blade 92 are in the form of a thin ribbon plate as in the first embodiment, and the width of the blade shape surface in the side view is the member width, and the blade shape surface in the axial direction is the member width. The width is defined as the member thickness, and the member thickness is formed to be equal to or less than the member width.

  When the arc-shaped stirring blade 9 formed in this way is engaged with the surrounding ground, the strip plate surface of the blade main body 91 is engaged with the surrounding ground with respect to the rotation direction of the excavation / stirring shaft 1. There is an effect of making the fixed state steadily by facing the engagement surface.

  Further, since the blade body 91 has a thin blade-shaped surface in the axial direction, the arc stirring blade 9 is formed along the axial direction of the drilling / stirring shaft 1 in accordance with the penetration / pulling operation of the drilling / stirring tool A8. When moved up and down, the frictional resistance is reduced.

  Further, when the arc-shaped stirring blade 9 vibrates in the radial direction by the amount of eccentricity in a side view by the above-mentioned “eccentric shaft structure”, the arc-shaped stirring blade 9 causes the blade main body portion 91 to engage with the surrounding ground. And the stationary agitation zone in the excavation and improved soil in the excavation hole are constantly moved to further reduce the frictional resistance associated with the penetration and extraction operations.

  Moreover, since the rotational resistance force is effectively obtained not only from the surrounding ground but also from the stationary agitation zone, it becomes a stationary state, so that even if the improvement construction target is a soft ground, the function of preventing the co-rotation of the arc-shaped agitating blade 9 is lost. There is no.

  With such a configuration, the engagement and fixing state of the arc-shaped stirring blade 9 to the surrounding ground is suppressed to a minimum, and a “shear line” is generated in the excavated and improved soil with the driving stirring blade. The “inhibiting action” and the “tightening preventing action” are generated, and the “corotation preventing effect” is reliably obtained, and the good kneadability of the excavated and improved soil can be ensured.

  As described above, according to the excavation / stirring tool according to the present invention, the unique arc-shaped stirring blade is provided with a structure straddling the eccentric shaft constructed with a special structure, so that the inside of the excavation hole is not dependent on the surrounding ground. By effectively utilizing the soil resistance of the excavated and improved soil, the arc-shaped agitating blade is vibrated, generating the “soil adhesion inhibiting action” and the “tightening preventing action”, while the “co-rotation preventing effect” is dramatically improved. It is possible to greatly improve the construction speed.

  In particular, the arc stirring blade functions as a co-rotation prevention blade that becomes stationary in the rotation direction of the excavation / stirring shaft by receiving resistance from the excavation / improved soil in the stationary stirring region at the blade body. However, excavation and vibration in the static agitation zone by vibrated vibration according to the amount of eccentricity, and functioning as a vertical shear rotary agitation blade that locally and partially rotates and agitates the soil, agitating to achieve uniform agitation throughout the improved body Improve the effect.

  That is, the excavation / stirring tool according to the present invention can cope with the tightening of the excavation / improvement soil regardless of the type of the surrounding ground, and the engagement depth of the co-rotation preventing wing to the surrounding ground is minimized. Alternatively, the co-rotation preventing wing can be brought into an immobile state without being engaged, and damage and deterioration of the wing and soil adhesion to the wing can be suppressed as much as possible, and the co-rotation phenomenon can be reliably prevented and the stirring efficiency can be improved.

  Finally, the description of each embodiment described above is an example of the present invention, and the present invention is not limited to the above-described embodiment, and each configuration disclosed in the above-described embodiment is mutually replaced or a combination is changed. Configurations, publicly known technologies, configurations disclosed in the above-described embodiments, configurations in which the configurations are mutually replaced, or combinations are changed are also included. In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made according to the design or the like as long as the technical idea of the present invention is not deviated. . It extends to the matters described in the claims and equivalents thereof.

A Drilling / stirring tool 1 Drilling / stirring shaft 2 Drilling blade 3 Drive stirring blade 4 Boss part (4a Upper boss part 4b Lower boss part)
5 Arc Stirring Wings 6 Floating Stirring Wings 7 Cantilever Stirring Wings S1 Drilling / stirring shaft rotation center line S2 Boss rotation center line S3 Arc stirring blades rotation center line

Claims (3)

In excavation and agitation tools for ground improvement by kneading excavated soil and improvement material while excavating and agitating the ground,
A drilling / stirring shaft extending vertically,
Supported by the lower end of the excavation and agitation shaft, excavation blade for excavating the ground,
A drive agitating blade that is supported on the outer peripheral surface of the excavation and stirring shaft and rotates integrally with the excavation and stirring shaft;
An arc-shaped stirring blade straddling the outer peripheral surface of at least two or more boss portions loosely fitted around the outer periphery of the excavation / stirring shaft, and bulging outward to form an arc,
The arc-shaped stirring blade is an outermost floating stirring blade that rotates in a floating state with respect to the excavation and stirring shaft,
The excavation / stirring tool characterized in that the rotation center line of the arc stirring blade is in an eccentric position inclined with respect to the rotation center line of the excavation / stirring shaft. In excavation and agitation tools for ground improvement by kneading excavated soil and improvement material while excavating and agitating the ground,
A drilling / stirring shaft extending vertically,
Supported by the lower end of the excavation and agitation shaft, excavation blade for excavating the ground,
A drive agitating blade that is supported on the outer peripheral surface of the excavation and stirring shaft and rotates integrally with the excavation and stirring shaft;
An arc-shaped stirring blade straddling the outer peripheral surface of at least two or more boss portions loosely fitted around the outer periphery of the excavation / stirring shaft, and bulging outward to form an arc,
The arc-shaped stirring blade is an outermost floating stirring blade that rotates in a floating state with respect to the excavation and stirring shaft,
The rotation center line of the arc-shaped stirring blades is the uppermost part and the lowermost boss part of at least two or more boss parts straddling the arc-shaped stirring blades with respect to the rotation center line of the excavation / stirring shaft An excavation / stirring tool characterized by being in an eccentric position inclined so as to intersect the rotation center line of the excavation / stirring shaft. 3. The excavation according to claim 1, wherein the arc-shaped stirring blade has a twisted shape or a shape inclined with respect to a coaxial direction with respect to a rotation center line of the arc-shaped stirring blade.・ Stirrer.

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