JPS6242090B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a multi-spindle press-in excavator equipped with a plurality of excavation shafts that move up and down along a leader.

[Technical background of the invention and its problems]

A conventional excavator is provided with an excavation shaft rotation drive device that can move vertically from the top to the bottom of a leader supported by a base machine. connect and
The excavation shaft is inserted into the ground while lowering the excavation shaft rotation drive device.The above-mentioned excavation shaft rotation drive device has a reduction gear structure and is heavy due to its function of rotating the excavation shaft. It is undesirable to move the reader between the upper and lower parts in terms of stability of the reader. In addition, when inserting the excavation shaft to a very deep place underground, it is possible to add more excavation shafts in sequence according to the depth of insertion into the ground.For this, conventional excavation shaft rotation drive devices It is necessary to perform this addition work below, but the excavation shaft rotation drive device has a reducer structure and has a large diameter, and the excavation shaft to be added is suspended by a wire hanging from the upper end of the leader, so the above-mentioned With the wire hanging down through the large-diameter outer circumference of the rotary drive device, it is difficult to bring the excavation shaft close to the center of the rotary drive device, and the excavation shaft rotation drive device becomes an obstacle, making it difficult to add more excavation shafts. It is difficult to
Therefore, in order to avoid such work as much as possible, we use the largest leader and continuously insert very long excavation shafts into the ground.
There are height restrictions, and depending on the conditions at the construction site, it may not be possible to erect such a long and large leader.

[Purpose of the invention]

The present invention is an excavator in which the vertical movement of an excavation shaft is guided by a leader, in which an excavation shaft rotation drive device can be provided under the leader, thereby stabilizing and downsizing the leader. be.

[Summary of the invention]

In the excavator of the present invention, a leader for guiding the vertical movement of a plurality of rows of excavation shafts is erected and supported by an upper support member and a lower support member protruding from a base machine, and the upper end of the leader A sprocket is rotatably supported at the lower end, and a chain is endlessly wound around the sprocket at the upper and lower ends.
A chain rotation driving device capable of rotating the chain in either forward or reverse directions is provided at the bottom of the leader, and the excavation shafts in each row have continuous corners on the outer surface from the upper end to the lower end. It is formed by a shaft that can connect multiple pieces in sequence, and a bit located at the bottom.
An endless fitting cylindrical body that has the same cross-sectional shape as the external shape of the shaft and is slidably fitted in an endless vertical direction to the shaft through a fitting hole that passes through the shaft in the vertical direction, and is rotatable via a bearing. At the same time, a plurality of excavation shaft rotation drive devices are provided, each consisting of a motor that rotationally drives this endless fitting cylindrical body, and which applies rotational force to any part of the shaft in each row.
A portion of the chain is connected to the slide base of the excavation shaft rotation drive device, and a part of the chain is connected to the slide base of the excavation shaft rotation drive device, and the chain of each row is connected to the leader above each excavation shaft rotation drive device. A plurality of excavation shaft pressure input action unit devices that apply a pressing force to the upper end of the excavation shaft via bearings are provided so as to be movable up and down via a common slide base, and the slide base of this excavation shaft pressure input action unit device is A self-propelled sprocket that meshes with the chain in a rack and pinion relationship is rotatably supported, and a motor is provided that can drive the self-propelled sprocket in either forward or reverse directions. The excavation shaft is press-fitted into the ground by the excavation shaft press-in input device while the excavation shaft is rotationally driven by the excavation shaft rotation drive device.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings.

As shown in FIG. 1, a support arm 3 as an upper support member and a pair of hydraulic cylinders 4 as a lower support member protrude from a swivel base 2 of a base machine 1 consisting of the main body of a power shovel, etc.
A leader 6 for guiding the vertical movement of the excavation shaft 5 is erected and supported. The support arm 3 is rotated in the vertical direction by a hydraulic cylinder 7.

The support arm 3 is formed so that an upper part 3a and a lower part 3b can be divided into two at the center, and are integrated by two shafts 8 and 9. Therefore, by removing one shaft 8 and using the other shaft 9 as a fulcrum, the upper part 3a is connected to the lower part 3.
It is possible to shorten the support arm 3 by folding it on the back side of the lower part 3b. In that case, the hole in the shaft 8 of the lower part 3b can be used to support a short leader of about 5 m, for example. , even if there is a height restriction, it can be accommodated.

Furthermore, as shown in FIG. 1, a leader vertical slide device 11 is provided on the right side of the leader 6. This fixes guide rails 12 and 13 to the upper and lower parts of the leader 6, and
Sliders 14 and 15 are fitted into the sliders 2 and 13 so as to be able to move up and down, and the sliders 14 and 15 are integrally connected by a connecting rod 16, and the cylinder body of the hydraulic cylinder 18 is attached to a bracket 17 fixed to the upper part of the leader. At the same time, the piston rod 19 is connected to the upper slider 14, and a leader orientation variable device 20 (described later) which is pivoted to the upper end of the support arm 3 is connected to the upper slider 14. The pair of hydraulic cylinders 4 are connected to the slider 15 of the hydraulic cylinder 18. When the piston rod 19 of the hydraulic cylinder 18 is pushed out against the sliders 14 and 15 supported in a fixed position by the support arm 3, the hydraulic cylinder 18 The leader 6 on the cylinder body side rises vertically, and in this state the base machine 1 can be moved and adjusted. Further, the leader 6 can be vertically lowered by reverse cylinder operation, and the leader 6 can be grounded at an accurate position.

Further, as shown in FIG. 1, the excavation shaft 5 provided along the leader 6 has a square hollow shaft 21 made of hexagonal pipes to which a plurality of pipes can be connected in sequence.
and a bit 22 located at the bottom, and the discharge port 23 is opened at the top and bottom. In addition, an excavator is fitted to the lower part of a pair of guide rods 24 provided on the left side of the leader 6 so as to be able to freely slide vertically endlessly with the shaft 21 of the excavator shaft 5, and which applies rotational force to any part of the shaft 21. An endless reducer 25 as a shaft rotation drive device is provided to be movable up and down, and above the endless reducer 25, a pushing force is applied to the upper end of the rotating excavation shaft 5 to the pair of guide rods 24 of the leader 6. An excavation shaft press-in force acting device (hereinafter simply referred to as a press-in device) 26 is provided to be movable up and down.

Furthermore, as shown in FIG. 1, sprockets 28 and 29 are rotatably supported on the upper and lower ends of the leader 6, and a double roller chain 30 is endlessly wound around the sprockets 28 and 29. A chain rotation drive device 31 for rotating the chain 30 is provided below the leader 6. This device 3
Reference numeral 1 denotes a speed reducer driven by a hydraulic motor 32, which applies rotational force selectable in forward and reverse directions to a drive shaft of a sprocket 29 at the lower end of the leader via a transmission mechanism 33.

As shown in FIG. 2, the endless reducer 2
5, three units are installed in parallel on a common pedestal 36. The endless reducer 25a in the center is fixed to the center of the pedestal 36 with bolts 37, and the endless reducers 25b and 25c on both sides slide along guides 38 provided on the pedestal 36 to connect to the center endless reducer 25a. The distance is adjusted and fixed at the adjusted position using the pin 39. Guides 38 of the endless reducers 25b and 25c on both sides
are provided on both sides of the pedestal 36, and insertion holes 40 for the pins 39 are bored at predetermined pitches, so that a fixing position by the pin 39 is selected from among the many insertion holes 40.

As shown in FIG. 2, a slide base 34 is integrally provided on the rear side of the pedestal 36, and a pair of slide brackets 41 integrally attached to both left and right sides of the slide base 34 are attached to the leader 6.
It is fitted into the guide rod portion 24 of the rod so as to be vertically movable.
The slide base 34 has a recess 35 formed in the center. A connecting piece 56 protruding from a part of the chain 30 is fitted into the recess 35, and a connecting pin 57 is fitted into the connecting piece 56 and the recess 35. is inserted to connect the slide base 34 and the chain 30.
Further, as shown in FIG. 2, each endless reducer 25a, 25b, 25c is connected to a
An endless fitting tube that is slidably fitted to the hexagonal hollow shaft 21 endlessly in the vertical direction through a regular hexagonal fitting hole 42 that has the same cross-sectional shape as the outer shape of the square hollow shaft 21 and penetrates in the vertical direction. It has a body 43 and a hydraulic motor 44 that rotationally drives the endless fitting cylinder 43.

As shown in FIG. 3, the endless fitting cylinder 43 is connected to the casing main body 4 through upper and lower bearings 46 held by upper and lower pressing plates 45.
A large-diameter gear 50 is integrally provided within the casing body 47 and meshes with a small-diameter gear 49 of the shaft 48 of the hydraulic motor 44. The hexagonal shaft 21 inserted into the endless fitting cylinder 43 penetrates downward through the hollow portion 51 of the pedestal 36. The guide 38 on the frame 36 and the lower slide plate 52 of the casing body 47 are easily slidably fitted together through a slide surface 53 made of grease or the like, and are fixed by the pin 39 inserted therethrough. The endless reducer 25a in the center is fixed with bolts.

As shown in FIGS. 4 and 5, two sprocket shafts 112 are rotatably provided at the upper and lower parts of the slide base 111 of the press-fitting device 26 via bearings 113, and each sprocket shaft 112
and two self-propelled sprockets 114 that mesh with the two rows of chains 30 in a rack and pinion relationship.
A pinion shaft 117 is rotatably provided in the casing 115 on one side of the slide base 111 via a bearing 116, and a spur gear 118 integrated with the sprocket shaft 112 is attached to the pinion shaft 117. A pinion gear 119 that meshes with the worm wheel 120 is integrally provided, and a worm 122 rotatably supported by a bearing 121 is meshed with the worm wheel 120.
The worm shaft 123 is connected to a drive shaft of a hydraulic motor 124 which can be rotated in either forward or reverse directions. Further, the slide base 111 rotatably supports a slide roller 125 that fits into the guide rod portion 24 of the leader via a slide roller bracket 126.
The upper and lower mounting portions 61 of the pedestal 60, which is movable up and down along the same axis and supports the press-fitting device 26, are fitted into the upper and lower recesses 127 of this slide base 111 and integrated by bolting, pinning, etc. do.

As shown in FIG. 6, three of the press-fitting devices 26 are installed in parallel on the pedestal 60, similar to the endless reducer 25, and the central press-fitting device 26a is connected to the center of the pedestal 60 by a plurality of pins 62. fixed to the
The press-fitting devices 26b and 26c on both sides are connected to the frame 60.
The spacing of the central press-fitting device 26a is adjusted by sliding it laterally along a guide (not shown) provided in the center, and the plurality of pins 6 are
Fix by 3. Note that this press-fitting device 26b, 2
The interval adjustment guides 6c are formed by providing guides such as the guides 38 shown in FIG. 3 at the upper and lower parts of the pedestal 60, respectively.

Returning to FIG. 4, the press-fitting device 26 rotatably supports a swivel shaft 67 by upper and lower tapered roller bearings 66 that are fitted into the upper and lower parts of the main body casing 64 and held by upper and lower pressing plates 65. , a swivel joint 68 is provided at the top of this swivel shaft 67. This swivel joint 68 rotatably fits the upper part of the swivel shaft 67 via the grease supply surface 71 into the lower part of the joint body 70 which is elastically supported by a plurality of springs 69, and 7
Attach the non-rotating side pipe connection part 72 to the upper part of the gasket 7.
3 to connect the inner hole 74 of the swivel shaft 67 and the inner hole 75 of the pipe connecting portion 72 to communicate with each other. The pipe connection part 72 is bolted to a disk 77 supported by a plurality of rib-like members 76 fixed on the upper holding plate 65, and the liquid solidification agent is connected to the upper end opening of the excavation shaft 5 through the swivel shaft 67. An external supply pipe 78 for supplying cement milk or compressed air is connected to this pipe connection 72. In addition, grease is supplied from a grease nipple 79 into the main body casing 64 to ensure smooth operation of the bearing 66, and the upper and lower bearing press plates 65
An oil seal 80 is fitted between the swivel shaft 67 and the swivel shaft 67 to prevent grease from leaking to the outside. Further, the upper part of the hexagonal hollow shaft 21 is fitted into the lower part of the swivel shaft 67, and a pair of pin insertion shafts 8 are inserted into the fitting surface.
Insert the connecting pin 82 into the hexagonal hollow shaft 2.
1 and the swivel shaft 67 are integrated. The press-fitting device 26 shown in FIG. 4 is fixed to the center of the pedestal 60 by the pin 62.

As shown in FIG. 6, the leader orientation variable device 20 includes a support arm-side member 86 rotatably attached to the upper end of the support arm 3 via a horizontal shaft 85.
and a leader side member 88 which is rotatably attached to the upper slider 14 via a horizontal shaft 87, and are rotatably connected via a vertical pivot shaft 89.
Cylinder mounting brackets 90, 91 are provided protruding from the side surfaces of both members 86, 88, and a hydraulic cylinder 92 is interposed between these two brackets 90, 91.

Then, by moving the piston rod 93 of the hydraulic cylinder 92 back and forth, the leader 6 can be rotated about the pivot shaft 86 within a range of ±45 degrees from the neutral position, and the direction of the leader 6 can be changed. . For example, as shown in FIG.
The support arm 3 protruding from the wall is oblique to the wall surface 94 when viewed from above, but by variable adjustment of the direction of the leader 6 around the pivot shaft 89, the support arm 3 is attached to the three press-fitting devices 26 and its lower part. The three endless speed reducers 25 located in the wall can be arranged to face each other in parallel. After changing the direction of the leader 6 in this manner, it is necessary to adjust the pair of hydraulic cylinders 4 that support the lower part of the leader in a figure-of-eight shape to maintain the verticality of the leader 6.

As shown in FIG. 8, the three excavation shafts 5 are
The shafts 5 are rotatably held by a pair of connecting plates 95 which are fitted into the lower portions of these from both sides and formed into a skewered dumpling shape by being fixed with bolts, thereby maintaining a constant spacing between the respective shafts 5. When adjusting the spacing between the shafts 5, the connecting plate 95 is removed and replaced with an appropriate connecting plate. In addition, the stirring blades 96 provided above the bit 22 and the connecting plate 95 are positioned such that the central excavation shaft is shifted downward from those of the excavation shafts on both sides. This is the adjacent bit 22 and stirring blade 96.
This is to prevent collision since they have overlapping diameters. Note that the stirring blade 96 is
It is provided to stir soil and cement milk as a liquid solidifying agent in the soil construction method.
Further, the discharge port 2 for discharging cement milk, compressed air, etc. to each shaft 5 below the connecting plate 95
3 is opened, and the inner hole of the hexagonal hollow shaft 21 is communicated with this discharge port 23. Further, the hexagonal hollow shaft 21 is such that a plurality of shafts can be connected in sequence, and at the connecting portion 97 of each shaft 21,
A gasket 98 is interposed between the inner holes, and a continuous uneven joint portion 99 formed on the outer peripheral surface is fitted,
Each shaft 21 is connected and fixed by inserting a pin 100 into the upper and lower double fitting portions. Then, by sequentially adding separate hexagonal hollow shafts between the hexagonal hollow shaft 21 at the top of each excavation shaft 5 and the hexagonal hollow shaft 21 below, the total length of the excavation shaft 5 can theoretically be It can be made endlessly long, and the lower part of the uppermost shaft 21 and below can be inserted into the ground. Moreover, the hexagonal hollow shaft 21 at the top is connected to the press-fitting device 26.
A coupling portion 101 is provided which fits on the lower outer circumferential surface of the swivel shaft 67, and a connecting pin 82 is inserted between the fitting surfaces as shown in FIG.

Returning to FIG. 1, the base machine 1 is detachably equipped with a pressure pump 102 for supplying cement milk, compressed air, etc. to the swivel joint 68 of the press-in device 26 via the external supply pipe 78. , this pump 102 is driven by a hydraulic motor. Note that this pump 102 may be used by lowering it onto the ground.

Furthermore, all of the above-mentioned hydraulic cylinders and hydraulic motors are each connected to a hydraulic power source built into the base machine 1, and the hydraulic pressure of this hydraulic power source drives the hydraulic cylinders to expand and contract, and rotates the hydraulic motor in forward and reverse directions. No external power source is required.

Next, the effect will be explained.

Before installing the excavation shaft 5, adjust the movement of the endless reducers 25b, 25c on both sides according to the diameter of the bit 22, and adjust the speed of each endless reducer 25a, 25.
b, 25c, and move and adjust the press-fitting devices 26b, 26c on both sides to adjust the spacing between each press-fitting device 26a, 26b, 26c,
These three sets of upper and lower corresponding press-fitting devices 26
a, 26b, 26c and endless reducer 25a,
Three excavation shafts 5 are attached to 25b and 25c, respectively.

During work, the chain rotation drive device 31 at the lower end of the leader is locked and the chain 30 is fixed.
The three endless reducers 25 are fixed in place,
In each endless reducer 25, the hydraulic motor 44 rotates the endless fitting cylindrical body 43 via the reducer gears 49 and 50, so that the excavation shaft 5 that fits into the hexagonal hole 42 of the cylindrical body 43 is rotated. While rotating the hexagonal hollow shaft 21, the self-propelled sprockets 114 at the upper and lower parts of the slide base 111 of the press-fitting device 26, which are meshed with the fixed chain 30 in a rack-and-pinion relationship, are driven by a hydraulic motor 124. By rotating through the worm 122, the worm wheel 120, and the gears 119, 118, the slide base 111 is moved downward by itself, and each press-fitting device 26 is driven up and down along the leader 6. Each rotating excavation shaft 5 is forcibly pushed down via the tapered roller bearing 66 inside, and the endless reducer 25 is in a fixed position.
It is press-fitted into the ground while sliding against the endless fitting cylinder 43 of.

At the same time, the pressure pump 102 simultaneously supplies cement milk as a liquid solidifying agent and compressed air to the swivel joint 68 of each press-fitting device 26 through the three external supply pipes 78 . The cement milk or the like is discharged from the discharge port 23 through the inner hole 74 and the inner hole of the excavation shaft 5, and is injected into the soil excavated by the bit 22. At this time, the cement milk is spread to every corner of the excavated soil by the pressurizing action of compressed air. This cement milk is homogeneously mixed with the excavated pulverized soil by the stirring action of stirring blades 96, etc.
It solidifies after a predetermined period of time and is used to improve soft ground, form continuous walls underground, etc.

The three excavation shafts 5 may rotate at the same speed or may rotate at different speeds. For example, it is conceivable that the excavation shaft at the side where the earth pressure resistance is high is driven at high speed by an endless reducer fitted thereto, and the excavation shaft at the central part where the earth pressure resistance is low is driven at a low speed. Further, the press-in speed of these three excavation shafts 5 and the cement milk supply flow rate are linked. This is the hydraulic motor 32 of the chain rotation drive device 31.
This can be easily done by connecting the hydraulic motor of the pressure pump 102 and the hydraulic motor of the pressure pump 102 in series to a common hydraulic power source of the base machine.

After the excavation shaft 5 is press-fitted until the press-fitting device 26 approaches the endless reducer 25, the hexagonal hollow shaft 21 at the top and the hexagonal hollow shaft 21 below are separated, and the press-fitting device 26 is inserted into the leader. It is returned to the upper part by itself, and is connected between the separated shafts 21, 21 via a separate hexagonal hollow shaft. By lowering the press-fitting device 26 again, the bit 22 can be inserted deeper into the ground. By sequentially adding hexagonal hollow shafts to the intermediate portion in this manner, the three excavation shafts 5 can be made as long as desired.

In addition, by bringing the slide base 111 of the press-fitting device 26 closer to the upper side of the endless reducer 25 and fixing the self-propelled mechanism of this press-fitting device 26 by the lock of the hydraulic motor 124, etc., this press-fitting device 26 can be attached to a part of the chain 30. In this way, the endless reducer 25 and the press-fitting device 26 can be fixed.
can be moved up and down integrally by the chain 30, and thereby, for example, the endless reducer 25 applies rotational force to the upper part of the auger screw having spiral blades over almost its entire length. can be press-fitted into the ground by the press-fitting device 26. In that case, if the three auger screws overlap, it is necessary to drive the three endless reducers 25 to rotate at the same speed.

Further, the hollow shaft 21 of the excavation shaft 5 in each row is 6
Although it is formed from a square pipe, it is not limited thereto, and any hollow elongated member having a continuous corner on the outer surface from the upper end to the lower end may be used, such as a square pipe, a pentagonal pipe, or even a continuous pipe. It may have a spline-shaped outer shape in that it has corners.

〔Effect of the invention〕

According to the present invention, the plurality of excavation shafts are fitted to the lower part of the leader in a vertically endless slidable manner with the shafts of the plurality of rows of excavation shafts, and apply rotational force to any part of the shafts in each row. A rotation drive device is provided, and above each excavation shaft rotation drive device, a plurality of excavation shaft press-in force acting unit devices are provided to the leader above each excavation shaft rotation drive device to apply a pressing force to the upper end of each of the rotated excavation shafts via a bearing. Since it is provided separately from the excavation shaft rotation drive device, there is no need for the excavation shaft rotation drive device to be lowered from the top of the leader together with the excavation shaft pressure input device when the excavation shaft is press-fitted into the ground. , in a fixed position at the bottom of the leader, the drilling shaft can be continuously rotated during descent. This excavation shaft rotation drive device has a reducer structure and is heavy due to its function of rotating the excavation shaft, but since this excavation shaft rotation drive device can be installed at the bottom of the leader, it has great stability and Between the excavation shaft rotation drive device and the excavation shaft pressure input device, the shafts of the excavation shafts can be successively added according to the depth of insertion into the ground, and thus a large-diameter excavation shaft rotation drive device can be used. The above-mentioned replenishment work can be easily performed without any obstacles, the reader can be made smaller, and this type of construction can be performed even when there is a height restriction. Further, a chain is wound endlessly along the leader, and the chain is driven to rotate in either forward or reverse directions by a chain rotation drive device, and a part of this chain is connected to the excavation shaft rotation drive device. The slide base is connected to the chain, and the self-propelled sprocket provided on the slide bracket of the excavation shaft pressure input action unit is engaged with the chain in the relationship between the rack and the pinion, so that it is rotationally driven by the motor. Lock the chain circulation drive device and fix the chain,
By rotating only the self-propelled sprocket, the excavation shaft can be efficiently forced into the ground without vibration or noise due to the self-propelled lowering of the excavation shaft press-in action device.
In addition, the height of the excavation shaft rotation drive device can be easily adjusted by rotating the chain, and the self-propelled sprocket of the excavation shaft pressure input device is integrated with the chain when the motor is stopped. This chain allows the excavation shaft pressure input device and the excavation shaft rotation drive device to be moved up and down at the same time, and, for example, the upper end of the auger screw can be rotated and pushed down. In this way, the chain can be effectively utilized in various ways, and has a wide range of applications, and the way it is used can be easily changed.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of the excavator of the present invention, FIG. 2 is a plan view of its excavation shaft rotation drive device,
Figure 3 is a cross-sectional view taken along the line - - in Figure 2, Figure 4 is a cross-sectional view of the excavation shaft pressure input device, and Figure 5 is a partially cutaway front view of the slide base of the excavation shaft pressure input device. , Figure 6 is a plan view of the peripheral area of the reader, and Figure 7 is a plan view of the peripheral area of the reader.
The figure is a plan view showing an example of the use of the variable reader orientation device.
FIG. 8 is a front view of the excavation shaft. DESCRIPTION OF SYMBOLS 1...Base machine, 3...Support arm as an upper support member, 4...Hydraulic cylinder as a lower support member, 5...Drilling shaft, 6...Leader, 21...Shaft, 22...Bit, 25...Drilling shaft rotation drive device 26... Excavation shaft pressure input device (press-fitting device), 28, 29... Sprocket, 30... Chain, 31... Chain rotation drive device, 34... Slide base, 42... Fitting hole, 43
...Endless fitting cylinder, 44...Motor, 46...Bearing, 66...Bearing, 111...Slide base, 114...Self-propelled sprocket, 124...
motor.

Claims (1)

[Claims] 1 A leader for guiding the vertical movement of multiple rows of excavation shafts is erected and supported by an upper support member and a lower support member protruding from the base machine, and sprockets are installed at the upper and lower ends of this leader. A chain rotating drive device is attached to the leader, which is rotatably supported, and a chain is endlessly wound around sprockets at the upper and lower ends of the chain, and the chain can be rotated in either forward or reverse directions. The excavation shafts in each row are provided at the bottom and are formed by a shaft having a continuous corner portion on the outer surface from the top end to the bottom end and capable of sequentially connecting a plurality of shafts, and a bit located at the bottom. , an endless fitting cylindrical body that is slidably fitted to the shaft endlessly in the vertical direction through a fitting hole that has the same cross-sectional shape as the outer shape of the shaft and passes through the shaft in the vertical direction is attached to the lower part of the leader. A common slide base is used to connect multiple excavation shaft rotation drive devices, each consisting of a motor that rotatably drives this endless fitting cylindrical body and provides rotational force to any part of the shaft in each row. A part of the chain is connected to the slide base of the excavation shaft rotation drive device, and a part of the chain is connected to the leader above each excavation shaft rotation drive device, and to the upper end of the excavation shafts of each row. A plurality of excavation shaft pressure input action unit devices that apply downward force through bearings are provided so as to be movable up and down via a common slide base, and the slide base of the excavation shaft pressure input action unit devices can be easily attached to the chain. A self-propelled sprocket that meshes with a pinion is rotatably supported, and a motor that can rotate the self-propelled sprocket in either forward or reverse directions is provided. Axial press-fit excavator.