JP7004981B2 - Bucket device for earth drill - Google Patents

Description

The present invention relates to a bucket device for an earth drill that is attached to the lower end of a keriba of an earth drill to excavate boulders, boulders, etc.

Conventionally, in the earth drill method, a drill bucket is attached to the lower end of a rotating shaft called a kelly bar, and the drill bucket is rotated and pressed downward to excavate the bottom of a vertical hole with a cutter provided on a conical bottom lid. However, it is a construction method in which excavated earth and sand are taken into the bucket from the opening provided in the bottom lid, and when the bucket is filled with earth and sand, the bucket is pulled up to the ground and discharged, and the construction speed is fast and the construction cost is low. It is widely used for foundation work such as high-rise buildings and condominiums.

In this earth drill method, boulders such as boulders and boulders cannot be taken in from the opening of the bottom lid with the drill bucket. Therefore, when excavating such a boulder zone, a grab bucket is used instead of the drill bucket. It is attached and the excavated material is grabbed by this grab bucket and discharged to the ground.

As such a bucket device for an earth drill, Patent Document 1 below discloses a configuration in which a hydraulic cylinder is extended and an open / close bucket is closed by pulling up a kelly bar in an excavator provided with an open / close bucket. ..

Further, in Patent Document 2 below, the pair of shell portions are opened when the connecting portion is located below the guide portion, and the pair of shell portions are closed when the connecting portion is located above the guide portion. The configuration is disclosed.

Japanese Patent No. 3818519 Japanese Unexamined Patent Publication No. 2015-224461

However, in the excavator described in Patent Document 1, since the hydraulic cylinder is used to open and close the openable bucket, the handling of the hydraulic hose becomes troublesome in the excavation work, and the hydraulic oil is sprinkled when the hydraulic hose is cut. There was a problem that it was scattered and it took time to process it. Further, when a hydraulic cylinder is used, the structure is complicated and maintenance is troublesome.

Further, in Patent Document 2, in order to close the pair of shell portions, the kelly bar is pulled up, the connecting portion connected to the lower end of the kelly bar is raised relative to the guide portion, and the connection portion is connected to the connecting portion. By raising the arm portion vertically, the shell portion connected to the lower end of the arm portion rotates around a pin that serves as a fulcrum for opening and closing. At this time, in Patent Document 2, the arm portion transmits the force when pulling up the kelly bar as it is to the shell portion as a normal force, and this normal force is converted into a rotational force with a pin as a fulcrum in the shell portion. As a result, the shell portion rotates. Therefore, the gripping force when the shell portion is closed is weak, and there is a possibility that the boulder cannot be reliably gripped, and the gripping amount at one time may be reduced.

Therefore, the main problem of the present invention is that an external force such as hydraulic pressure is not required to open and close the bucket, the gripping force at the time of closing the bucket is strong, the gripping amount at one time can be stably obtained, and the structure is simple. To provide a bucket device for drills.

The present invention according to claim 1 in order to solve the above problems is a bucket device for an earth drill that is detachably attached to the lower end of a kelly bar.
A cylindrical casing with an open lower surface and a rotatably supported casing inside the casing that can be opened and closed between an open position where the lower surface side of the casing is open and a closed position where the lower surface side of the casing is closed. It is provided with a pair of left and right buckets, and a connecting member provided inside the casing and moving in the vertical direction integrally with the kelly bar.
The connecting member is provided with a separation from each other on the side on which the bucket is arranged, and a pair of left and right tapered grooves formed so that the separation distance gradually increases toward the lower side are provided substantially in the vertical direction. Formed along
One end of the connecting member and the bucket is rotatably and rotatably supported along the tapered groove, and the other end is rotatably supported by the bucket and rotatably connected to each other at the intersection. Provided is a bucket device for an earth drill, which is connected by an X-shaped link member and is configured to move the bucket from the open position to the closed position by pulling up the kelly bar. ..

The invention according to claim 1 is a bucket device for an earth drill used by attaching to the lower end of a keriba instead of a drill bucket when excavating a boulder zone such as a ball stone or a boulder with an earth drill, wherein the casing and the casing are used. Inside the casing, a pair of left and right buckets for gripping boulders rotatably supported by the casing, and a connecting member that moves in the vertical direction integrally with the kelly bar are provided. The connecting member is formed with tapered grooves that are separated from each other to the left and right along substantially the vertical direction. The connecting member and the bucket are connected by an X-shaped link member, and the X-shaped link member is rotatably connected to each other at an intersection. Then, by pulling up the kelly bar, the connecting member moves upward integrally with the kelly bar, and one end of the X-shaped link member moves along the tapered groove to move the bucket through the link mechanism. It is possible to move from the open position to the closed position.

As described above, since the bucket device for the earth drill does not use an external force such as hydraulic pressure as a drive source for opening and closing the bucket, it is not necessary to handle the hydraulic hose, the workability is improved, and the structure is simplified. It can be converted and maintenance work can be saved. Further, the toggle mechanism is applied by deforming one end of the X-shaped link member that rotates the bucket when the kelly bar is pulled up along the tapered groove so that the X-shaped link member gradually expands. Since the bucket is closed by the mechanism, a strong cutting edge force can be generated when the bucket is closed, and it becomes possible to reliably grab boulders and the like, and a stable gripping amount can be obtained at one time. Will be.

According to the second aspect of the present invention, a cylindrical guide cover provided on the upper surface of the casing and a shaft fixed to the lower end of the kelly bar and sliding inside the guide cover so as to be movable in the axial direction and have a shaft. Equipped with a joint shaft that can rotate around
A stopper protruding from the peripheral surface of the joint shaft is provided, and an engaging groove with which the stopper can be engaged is provided along the vertical direction in the guide cover, and the stopper is provided at the lower end of the engaging groove. The bucket device for an earth drill according to claim 1, wherein a lock portion is formed which is locked to prevent the joint shaft from moving in the axial direction.

In the invention according to claim 2, in order to hold the bucket in the open position during excavation by the bucket device, a stopper is provided on the peripheral surface of the joint shaft, and the stopper is formed at the lower end of the engaging groove. It can be locked to.

As described in detail above, according to the present invention, an external force such as hydraulic pressure is not required to open and close the bucket, the gripping force when the bucket is closed is strong, and a single gripping amount can be stably obtained, and a simple structure is obtained. A bucket device for earth drills will be available.

It is a vertical sectional view of the bucket device 1 for an earth drill (when the bucket is opened). It is a vertical sectional view of the bucket device 1 for an earth drill (when the bucket is closed). FIG. 3 is a view taken along the line III-III of FIG. FIG. 1 is a view taken along the line IV-IV of FIG. It is a VV line arrow view of FIG. It is a top view which shows the link member 25.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The bucket device 1 for an earth drill according to the present invention is detachably attached to the lower end of a keriba of an earth drill instead of a drill bucket when excavating boulders such as boulders and boulders that cannot be excavated by a drill bucket.

As shown in FIGS. 1 and 2, the earth drill bucket device 1 is rotatably supported by a cylindrical casing 2 having an open lower surface and the casing 2 inside the casing 2, and the casing is supported. A pair of left and right buckets 3 and 3 that can be opened and closed at an open position (FIG. 1) in which the lower surface side of 2 is open and a closed position (FIG. 3) in which the lower surface side of the casing 2 is closed, and the upper surface of the casing 2. A cylindrical guide cover 4 having an open upper and lower surface provided at a position substantially coaxial with the casing 2 and fixed to the lower end of the kelly bar, and the casing is fixed from an opening on the upper surface of the guide cover 4. A joint shaft 5 inserted inside the guide cover 4 so as to be slidable inside the guide cover 4 so as to be movable in the axial direction and rotate around the axis, and a joint shaft 5 provided inside the casing 2. It includes a connecting member 6 attached to the lower end of the portion 5 and moving in the vertical direction integrally with the casing, and a link member 25 for connecting the connecting member 6 and the bucket 3.

The casing 2 has a substantially cylindrical outer shape in which the entire lower surface is opened and a part of the center of the upper surface is opened. At the lower end of the casing 2, a plurality of bits 7, 7 ... Are provided so as to project downward at intervals in the circumferential direction. On the peripheral surface of the casing 2, openings 8 and 8 penetrating the inside and outside of the casing 2 are formed on the left and right sides, respectively, having a size slightly larger than the size along the peripheral surface of the casing 2 of the bucket 3 in the open position. As shown in FIGS. 1 and 3, the opening 8 is formed in such a size that the outer peripheral portion of the bucket 3 in the open position can be fitted with a gap on the outer periphery.

Inside the casing 2, a cylindrical inner case 9 is provided which is separated inward by a predetermined distance from the inner peripheral surface of the casing 2 and which hangs down from the upper surface of the casing 2. Support portions 10 and 10 for rotatably supporting the buckets 3 and 3 are provided on the left and right sides of the lower end of the inner case 9, and on the left and right sides of the inner peripheral surface, respectively, on the left and right sides of the connecting member 6. Engagement grooves 11 and 11 with which the protrusions 6a provided are engaged are formed along the vertical direction.

The bucket 3 is formed in an arc shape in cross section, is arranged so as to fit into the opening 8 of the casing 2 at the open position shown in FIG. 1, and the tips are abutted against each other at the closed position shown in FIG. It is composed of a bottom portion 3a arranged so as to close the opening on the lower surface of No. 2 and flat plate-shaped side portions 3b and 3b standing on both sides of the bottom portion 3a. At the open position of the buckets 3 and 3 shown in FIG. 1, the ground is excavated by the bits 7, 7 ... Provided at the lower end of the casing 7, and then the buckets 3 and 3 are moved to the closed position shown in FIG. As a result, the earth and sand that has entered the casing 2 is grasped by the upper part of the portion surrounded by the bottom portion 3a and the side portion 3b of the left and right buckets 3 and 3.

A support plate 12 is provided so as to project from the upper portion of the inner surface of the bottom portion 3a, and the support plate 12 is rotated by a shaft member that integrally penetrates the support portion 10 provided in the casing 2 (inner case 9). By being movably supported, the bucket 3 is rotatably supported with respect to the casing 2.

Further, a connecting plate 13 to which a link member 25 for rotating the bucket 3, which will be described in detail later, is connected is provided on the side portion 3b of the bucket 3 so as to project.

On the other hand, the guide cover 4 is formed in a cylindrical shape with the upper surface and the lower surface open, and is fixed to the upper surface of the casing 2 in a state where the opening on the lower surface communicates with the opening provided in the center of the upper surface of the casing 2. Has been done. As a result, the inside of the guide cover 4 is arranged so as to communicate with the inside of the casing 2.

On the peripheral surface of the guide cover 4, an engaging groove 14 with which a stopper 18 protruding from the peripheral surface of the joint shaft 5 described in detail later can be engaged is provided along the vertical direction. At the lower end of the engaging groove 14, a lock portion 15 is formed in which the stopper 18 is engaged to prevent the joint shaft 5 from moving in the axial direction. The lock portion 15 is a portion wider than the engagement groove 14 formed at the lower end portion of the engagement groove 14, and the stopper 18 rotated in the rotation direction (R direction) of the kelly bar during excavation is engaged. This is to prevent it from moving in the vertical direction.

As shown in FIG. 5, at the lower ends of the lock portion 15 and the engagement groove 14, the protrusion portion protruding toward the inside of the lock portion 15 and the engagement groove 14 has a protrusion 16a, and the stopper 18 has the engagement groove. A stop member 16 that prevents the 14 and the locking portion 15 from moving downward is fixed to the upper surface of the casing 2.

Inside the guide cover 4, the joint shaft 5 having an outer shape with a circular cross section is slidably inserted. A square cylindrical connecting portion 17 is formed at the upper end of the joint shaft 5, and the connecting portion 17 is engaged with the lower end of the kelly bar to insert the pin member into the pin hole 17a for the earth drill. The bucket device 1 is attached to the kelly bar, and the joint shaft 5 can rotate and move up and down integrally with the kelly bar.

A stopper 18 projecting outward is provided on the peripheral surface of the joint shaft 5. As shown in FIG. 5, the stopper 18 is composed of a shaft member having a substantially square cross section penetrating the cylindrical joint shaft 5 in the radial direction, and the shaft member is provided with an opening on the peripheral surface of the joint shaft 5. Both ends are fixed so as to protrude outward from the portion.

An enlarged flange portion 19 is formed at the lower end of the joint shaft 5, and the flange portion 19 is connected to the upper portion of the connecting member 6 by a predetermined connecting structure, so that the joint shaft 5 can rotate. It is configured so that it is not transmitted to the connecting member 6 and only the movement in the vertical direction can be transmitted.

Next, the connecting member 6 is attached to the lower end of the joint shaft 5 and is connected to the upper portion 20 of the connecting member formed in a substantially disk shape having a predetermined connecting structure with the joint shaft 5 and to the lower side thereof. It is composed of a substantially square box-shaped connecting member lower portion 21 which is provided and has a connecting structure with a link member 25 described later.

The connecting member upper portion 20 is formed on a substantially circular substrate 20a in a plan view and an annular rib 20b formed on the upper surface of the substrate 20a and into which a flange portion 19 provided at the lower end of the joint shaft 5 can be fitted. And the annular pressing plate 20c that presses the flange portion from above in a state where the flange portion 19 is fitted to the rib 20b, and a plurality of the pressing plates 20c are provided at intervals in the circumferential direction. It is fixed to the substrate 20a by the fixing bolts 20d, 20d .... In the connected state between the joint shaft 5 and the connecting member 6, the flange portion 19 is fitted inside the rib 20b, and the holding plate 20c is fixed to the upper surface thereof. As a result, the joint shaft 5 and the connecting member 6 are relatively rotatable, but cannot move in the vertical direction. Therefore, the rotation of the joint shaft 5 is absorbed by the connecting portion and is not transmitted to the connecting member 6, and only the vertical movement of the joint shaft 5 can be transmitted to the connecting member 6.

Further, on the left and right sides of the substrate 20a, protrusions 6a capable of engaging with engaging grooves 11 along the vertical direction formed on the left and right sides of the inner peripheral surface of the inner case 9, respectively, are provided, and the protrusions 6a are provided. Is provided so that the connecting member 6 is relatively non-rotatable with respect to the casing 2 and is movable in the vertical direction by engaging with the engaging groove 11.

The lower portion 21 of the connecting member is formed in a hollow box shape formed of a substantially rectangular parallelepiped or a cube, and the left and right side plates 21a and 21a facing the side on which the buckets 3 and 3 are arranged, and the left and right side plates 21a and 21a. It has front and rear side plates 21b and 21b facing orthogonal sides. The connecting member lower portion 21 is integrally joined to the connecting member upper portion 20.

Of the connecting members 6, the front and rear side plates 21b and 21b of the connecting member lower portion 21 are provided apart from each other on the side where the buckets 3 and 3 are arranged, respectively, and as the separation distance increases downward. A pair of left and right tapered grooves 22 and 22 formed so as to gradually increase are formed along substantially the vertical direction. The tapered groove 22 is an opening that penetrates the front and rear side plates 21b and communicates the inside and the outside of the connecting member lower portion 21, and is formed by an inclined linear elongated hole. The tapered grooves 22 and 22 are formed symmetrically with respect to the front and rear side plates 21b with respect to the axial center line L of the kelly bar, and are formed at the same positions with respect to the front and rear side plates 21b and 21b, respectively. ing. As shown in FIG. 1, the inclination angle α of the tapered groove 22 with respect to the center line L of the kelly bar is arbitrary, but is preferably 5 to 45 °, preferably 10 to 30 °.

As shown in FIG. 6, among the tapered grooves 22 formed in the front and rear side plates 21b and 21b, the tapered grooves 22 straddle between the tapered grooves 22 and 22 corresponding to the front and rear directions, and are movable along the tapered grooves 22. Moreover, a rotatable slide shaft 23 is arranged. The slide shaft 23 is provided so as to penetrate the hollow inside of the lower portion 21 of the connecting member, both ends thereof are inserted into the tapered groove 22, and the tip thereof protrudes from the tapered groove 22. The tip of the slide shaft 23 protruding from the tapered groove 22 is threaded on the outer periphery so that it can be screwed with a nut with one end of the link member 25 described later inserted.

One end of the connecting member 6 and the bucket 3 is movably and rotatably supported along the tapered groove 22, and the other end is rotatably supported by the bucket 3 and rotates with each other at an intersection. It is connected by an X-shaped link member 25 that is movably connected. As a result, the left and right buckets 3 and 3 can be moved from the above-mentioned open position (FIG. 1) to the closed position (FIG. 2) by pulling up the kelly bar.

The link member 25 is formed into an X shape as a whole by intersecting one link member 25A and the other link member 25B at an intermediate portion and rotatably connecting at this intersecting portion. One link member 25A is fixed to the slide shaft 23 arranged in the tapered groove 22B on the other side of the tapered grooves 22A and 22B whose one end is arranged in pairs with respect to the axial center line L of the keriba. Of the buckets 3A and 3B arranged in pairs on the left and right with respect to the axial center line L of the keriba, the other end is rotatably connected to the connecting plate 13 provided on the bucket 3A on one side. Further, one end of the other link member 25B is fixed to the slide shaft 23 arranged in the tapered groove 22A on one side, and the other end is rotatably connected to a connecting plate 13 provided in the bucket 3B on the other side. Has been done. One end of the link members 25A and 25B is fixed to the slide shaft 23, and the slide shaft 23 is rotatably and movably provided with respect to the tapered groove 22, so that the tapered groove 22 can be rotated and moved. It is designed to be arranged as possible.

In order to rotatably connect the one link member 25A and the other link member 25B at the intersection, the one link member 25A and the other link member 25B are integrally connected as shown in FIG. It is preferably connected by a pen member 26 that penetrates. It is preferable to use a nut with a detent for fixing the pin member 26, cut out a part of the nut on the head, and fix the detent key plate to the notch. In the illustrated example, in the link member 25 provided at one end of the link members 25 and 25 provided at both ends of the slide shaft 23, one of the link members 25A is separated by a predetermined distance in the thickness direction. The other link member 25B is composed of two plates arranged at a distance, the other link member 25B is composed of one plate material having a thickness that can be inserted into the separated portion, and the other link member 25B is composed of one link member 25A. In the link member 25 provided at the other end of the link member 25, which is inserted into the separation portion between the plate members and connected by the pin member 26, one link member 25A and the other link member 25B are reversed. After having a structure, it is connected by the pin member 26. As a result, the bond strength of the left and right connecting structures can be made equal.

It is preferable that the pin member 26 is also used to rotatably support the other end of the link member 25 that connects the link member 25 to the bucket 3.

Next, an excavation method using the earth drill bucket device 1 will be described. The earth drill bucket device 1 is attached to the lower end of the kelly bar, the joint shaft 5 is moved to the lowermost position, and the kelly bar is rotated in the excavation direction (R direction in FIG. 1) with the stopper 18 locked to the lock portion 15. The ground is excavated while the ball stones, boulders, and the like are housed in the casing 2 by a plurality of bits 7, 7 ... Provided at the lower end of the casing 2.

Then, when the excavated boulders, boulders, etc. are accumulated in the casing 2, the kelly bar is rotated in the direction opposite to the excavation direction (R direction), the locked state in which the stopper 18 is engaged with the lock portion 15 is released, and the kelly bar is released. Move it upwards. At this time, the joint shaft 5 rotates together with the rotation in the direction opposite to the excavation direction of the kelly bar, but the connecting member 6 attached to the lower end of the joint shaft 5 absorbs the rotational movement at these connecting portions. Therefore, it does not rotate and only moves in the vertical direction.

When the kelly bar is moved upward, the frictional resistance between the peripheral surface of the casing 2 and the inner surface of the excavation hole and the weight of the casing 2 (including the inner case 9), the bucket 3, the guide cover 4, the link member 25, etc. , Only the joint shaft 5 and the connecting member 6 move upward relative to the casing 2, and the casing 2 and the like try to stay in place. Since the slide shaft 23 moves relatively downward along the tapered groove 22 as the connecting member 6 moves upward, the separation distance at the upper end of the link member 25 gradually increases. As a result, the upper end (fulcrum C) of the X-shaped link member 25 is deformed so as to spread to the left and right around the fulcrum D at the intersection, and the lower end (fulcrum B) of the link member 25 supports the bucket 3 with respect to the casing 2. A moment is generated in which the bucket 3 tends to rotate about the point (fulcrum A) in the closing direction. The moment acting on the fulcrum B becomes a driving force, and the bucket 3 can rotate around the fulcrum A and close. In this way, the link mechanism consisting of the fulcrums A, B, and C closes the bucket 3 by a mechanism that applies the toggle mechanism, so that a strong cutting edge force can be generated when the bucket 3 is closed, and boulders, boulders, etc. are reliably secured. You will be able to grab it, and you will be able to obtain a stable amount of grip at one time.

Ignoring the frictional resistance between the peripheral surface of the casing 2 and the inner surface of the excavation hole, the reaction force when the kelly bar is pulled up is applied to the non-movable part of the bucket device (members constituting the bucket device 1 other than the joint shaft 5 and the connecting member 6). ), The force for pushing the upper end of the link member 25 is the force for closing the bucket 3, and the force for the bucket 3 is the force for grasping an object. The force F that pushes the link member 25 apart is obtained from F = H / sinα. Here, H is the pulling force of the kelly bar and is the weight of the non-movable portion. α is the inclination angle of the tapered groove 22 with respect to the center line L of the kelly bar.

In this way, when the joint shaft 5 is pulled up relative to the casing 2 and the buckets 3 and 3 are closed, the kelly bar is further pulled up so that the entire bucket device 1 for the earth drill can be pulled up. In the ground drill bucket device 1 pulled up to the ground, the joint shaft 5 and the connecting member 6 are relatively downward with respect to the casing 2 by moving the kelly bar downward in a state where the bucket device 1 is placed in a predetermined area at the site. As the fulcrum C of the link member 25 with respect to the tapered groove 22 moves relatively upward along the tapered groove 22 and the left and right separation distances of the upper ends of the X-shaped link member 25 become smaller, The left and right separation distances at the lower ends are also reduced, the buckets 3 and 3 are opened, and the excavated earth and sand held by the buckets 3 and 3 is discharged to the outside.

The earth drill bucket device 1 having the above configuration does not use external force such as hydraulic pressure or wire as a drive source for opening and closing the bucket 3, so that it is not necessary to handle hydraulic hoses and wires, which hinders excavation work. Does not cause a problem. In addition, since it is not equipped with a hydraulic cylinder, the structure can be simplified and maintenance work can be saved.

Further, the upper end of the X-shaped link member 25 that rotates the buckets 3 and 3 when the kelly bar is pulled up moves along the tapered groove 22, and the X-shaped link member 25 moves left and right around the fulcrum D of the intersection. By deforming to expand to, the buckets 3 and 3 are closed by a mechanism that applies the toggle mechanism, so that a strong cutting edge force can be generated when the buckets 3 and 3 are closed, and boulders and the like can be reliably grasped. You will be able to do this, and you will be able to obtain a stable amount of grip at one time.

1 ... Bucket device for earth drill, 2 ... Casing, 3 ... Bucket, 4 ... Guide cover, 5 ... Joint shaft, 6 ... Connecting member, 7 ... Bit, 8 ... Opening, 9 ... Inner case, 10 ... Support part, 11 ... engaging groove, 12 ... support plate, 13 ... connecting plate, 14 ... engaging groove, 15 ... locking part, 16 ... stopping member, 17 ... connecting part, 18 ... stopper, 19 ... flange part, 20 ... connecting member Upper part, 21 ... Lower part of connecting member, 22 ... Tapered groove, 23 ... Slide shaft, 25 ... Link member

Claims (2)

A bucket device for earth drills that can be detachably attached to the lower end of the keriva.
A cylindrical casing with an open lower surface and a rotatably supported casing inside the casing that can be opened and closed between an open position where the lower surface side of the casing is open and a closed position where the lower surface side of the casing is closed. It is provided with a pair of left and right buckets, and a connecting member provided inside the casing and moving in the vertical direction integrally with the kelly bar.
The connecting member is provided with a separation from each other on the side on which the bucket is arranged, and a pair of left and right tapered grooves formed so that the separation distance gradually increases toward the lower side are provided substantially in the vertical direction. Formed along
One end of the connecting member and the bucket is rotatably and rotatably supported along the tapered groove, and the other end is rotatably supported by the bucket and rotatably connected to each other at the intersection. A bucket device for an earth drill, which is connected by an X-shaped link member and is configured to move the bucket from the open position to the closed position by pulling up the kelly bar. A cylindrical guide cover provided on the upper surface of the casing and a joint fixed to the lower end of the kelly bar and slid inside the guide cover so as to be movable in the axial direction and rotatable around the axis. Equipped with a shaft,
A stopper protruding from the peripheral surface of the joint shaft is provided, and an engaging groove with which the stopper can be engaged is provided along the vertical direction in the guide cover, and the stopper is provided at the lower end of the engaging groove. The bucket device for an earth drill according to claim 1, wherein a lock portion that is locked to prevent the joint shaft from moving in the axial direction is formed.

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