Soil improvement machine

Abstract

To secure a sufficient clamping force between a shaft clamping mechanism and an agitating shaft during a grip-changing operation of the agitating shaft by a hydraulic chuck mechanism and the shaft clamping mechanism, thereby reliably preventing the agitating shaft from dropping during the grip-changing operation of the agitating shaft.SOLUTION: A push piece 33 having a radius of curvature R equal to an outer circumferential arc of an agitating shaft 11 is attached to a tip end of a rod 32 of a cylinder 31. Left and right clamp pieces 4cL and 4cR also have radii of curvature equal to the outer circumferential arc of the agitating shaft 11. Furthermore, the cylinder 31 is installed so that a bisector 33CL of the push piece 33 intersects a clamping direction 4Y of a shaft clamping mechanism 4 and passes through a center 5C of a guide inner circumferential circle of a shaft guide mechanism 5. The clamping direction 4Y of the shaft clamping mechanism 4 also passes through the center 5C of the guide inner circumferential circle of the shaft guide mechanism 5.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a ground improvement machine, and more specifically to a ground improvement machine that ensures sufficient clamping force between the shaft clamping mechanism and the agitator shaft during the agitator shaft replacement operation using a hydraulic chuck mechanism and a shaft clamping mechanism, thereby reliably preventing the agitator shaft from falling during the agitator shaft replacement operation. [Background technology]

[0002] In recent years, there has been an increase in ground improvement work that uses mechanical mixing methods (slurry-type mechanical mixing methods) to create a large number of cylindrical improvement bodies (ground improvement piles) in the ground, with the objectives of "strengthening the bearing capacity," "reducing subsidence," "preventing liquefaction," and "reinforcing the earthquake resistance of existing structures" in soft ground.The ground improvement piles are created in a cylindrical shape using a ground improvement machine equipped with a rotary drive device (swivel head) that rotates a casing rod with a specified torque, and a feeding device (leader device) that raises and lowers the rotary drive device with a specified feeding force.

[0003] The casing rod is also called the mixing shaft, and a mixing device is attached to the lower end of the casing rod. The mixing device consists of an "excavation blade" with multiple bits that excavate the ground, an "mixing blade" that mixes and mixes the cement-based solidifying agent and soil, and a "co-rotation prevention blade" that prevents the soil from rotating together with the mixing blade. Near the tip of the mixing device, there are multiple nozzles that spray the solidifying agent.

[0004] In addition, a grout hose is connected to the upper tip of the casing rod via a water swivel mechanism, and grout (cement-based solidifying agent) flows inside the casing rod and is discharged into the ground from a nozzle. Therefore, the quality of the ground improvement pile is judged, for example, by the solidifying agent discharge flow rate (L) per section depth (for example, 1 m) and the number of blade cuts per section depth (= number of casing rod rotations x number of mixing impeller blades).

[0005] While the agitator shaft rotates, it is gripped by a hydraulic chuck mechanism mounted coaxially with the rotary drive device (swivel head) and rotates integrally with the swivel head to prevent it from falling. As shown in Figure 9, if the excavation depth is within the range of 6900 mm, calculated by subtracting the minimum ground clearance of the agitator (mixing bit) (400 mm) from the leader device's feed stroke (7300 mm), no agitator shaft re-gripping operation is required. The "agitator shaft re-gripping operation" here refers to the operation of changing the gripping position of the agitator shaft by the hydraulic chuck mechanism. Specifically, the hydraulic chuck mechanism is released while the agitator shaft is gripped by the leader device's clamping mechanism. Next, the leader device raises or lowers the swivel head to the desired position. When the swivel head reaches the desired position, the hydraulic chuck mechanism grips the agitator shaft again, and the leader device's clamping mechanism is released.

[0006] On the other hand, as shown in Figure 10, if the excavation depth exceeds the depth (= 6,900 m) obtained by subtracting the "minimum ground clearance of the agitator" from the "feed stroke of the leader device," one or more agitator shaft re-gripping operations are required. Figure 11 is an explanatory diagram showing the penetration process (Step 3 ⇒ Step 4 ⇒ Step 5 ⇒ Step 6 ⇒ Step 7 ⇒ Step 8 ⇒ Step 9 ⇒ Step 10) and the pull-up process (Step 10 ⇒ Step 9 ⇒ Step 8 ⇒ Step 7 ⇒ Step 6 ⇒ Step 5 ⇒ Step 4 ⇒ Step 3) for constructing a soil improvement pile approximately 25 m long. Three agitator shaft re-gripping operations are required during the penetration process. Similarly, three agitator shaft re-gripping operations are required during the pull-up process. Therefore, a total of six agitator shaft re-gripping operations are required during the penetration and pull-up processes. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-234527 [Patent Document 2] Japanese Patent Publication No. 2022-001727 Summary of the Invention [Problem to be solved by the invention]

[0008] As shown in Figure 11, leader rails are provided on both the left and right sides of the reader device in the longitudinal direction (axial direction) to allow the swivel head to move up and down along the reader device. U-shaped slide hangers are provided on both the left and right sides of the swivel head to slide along the leader rails. A gap exists between the slide hangers and the leader rails.

[0009] The swivel head is equipped with two rotation motors (left and right), two lifting motors (left and right), two guide rods (left and right), hydraulic equipment such as a hydraulic chuck mechanism, and a stirring shaft, so a rotational moment is constantly applied to the swivel head, tending to tilt the machine forward.

[0010] Therefore, as shown in Figure 12, when the swivel head tilts toward the front of the machine, the entire swivel head rotates counterclockwise around the center of gravity. As a result, the part of the agitator shaft located below the center of gravity moves toward the rear of the machine (toward the leader device). As a result, the part of the agitator shaft located inside the clamping mechanism of the leader device also moves toward the rear of the machine (toward the leader device).

[0011] In this case, as shown in Figure 13(a), the axis of the agitator shaft becomes eccentric (misaligned) from the clamping direction. As a result, as shown in Figure 13(b), it becomes impossible to ensure sufficient contact between the clamp piece and the agitator shaft. In other words, the agitator shaft cannot be adequately gripped by the clamp mechanism (clamp piece) of the leader device.

[0012] As a result, for example, during the operation of replacing the agitator shaft in the pulling process, the agitator shaft may slip off the clamping mechanism of the leader device. If the agitator shaft slips off, an excessive load is applied to the guide rod supporting the water swivel mechanism and the water swivel mechanism, and in the worst case scenario, the guide rod and the water swivel mechanism may be damaged.

[0013] Therefore, the present invention has been made in consideration of the problems of the above-mentioned conventional technology, and its purpose is to provide a ground improvement machine that ensures sufficient clamping force between the shaft clamping mechanism and the agitator shaft when the agitator shaft is replaced using a hydraulic chuck mechanism and a shaft clamping mechanism, thereby preventing the agitator shaft from falling during the replacement operation. [Means for solving the problem]

[0014] The ground improvement machine of the present invention for achieving the above-mentioned object is a ground improvement machine comprising a rotary drive device (1) for rotating an agitator shaft (11), a lifting device (2) for raising and lowering the rotary drive device (1) in a predetermined direction, a hydraulic chuck mechanism (3) for fixing the position of the agitator shaft (11) relative to the rotary drive device (1) so that the agitator shaft (11) can rotate, a shaft clamping mechanism (4) for fixing the position of the agitator shaft (11), and a shaft guide mechanism (5) for determining the direction of the shaft center (11C) of the agitator shaft (11), characterized in that the lifting device (2) has a shaft pushing mechanism (30) that intersects the clamping direction (4Y) of the shaft clamping mechanism (4) relative to the agitator shaft (11) and can push the agitator shaft (11) in the direction of the opening center (5C) of the shaft guide mechanism (5).

[0015] In the above configuration, the shaft pushing mechanism 30 can position the agitator shaft 11 in the clamping direction 4Y of the shaft clamping mechanism 4. This makes it possible to prevent the shaft clamping mechanism 4 from improperly clamping the agitator shaft 11.

[0016] The second feature of the ground improvement machine of the present invention is that the axial extrusion mechanism (30) comprises a cylinder (31) that moves a rod (32) back and forth along the axial direction, a contact member (33) that is attached to the tip of the rod (32) and contacts the outer peripheral surface of the stirring shaft (11), a storage case (34) that stores the contact member (33), and a cylinder support mechanism (40) that supports the cylinder (31).

[0017] In the above configuration, when the rod 32 moves forward in the axial direction, the abutment member 33 pushes the agitator shaft 11, thereby positioning the agitator shaft so that the shaft center 11C of the agitator shaft is positioned in the clamping direction 4Y of the shaft clamping mechanism 4. This reliably prevents the shaft clamping mechanism 4 from failing to clamp the agitator shaft 11.

[0018] The third feature of the ground improvement machine of the present invention is that, among the left and right gripping members (4cL, 4cR) of the shaft clamping mechanism (4) and the abutment members (33) of the shaft pushing mechanism (30), at least the left and right gripping members (4cL, 4cR) have surfaces (4cLa, 4cRa) that contact the agitator shaft (11) with a radius of curvature (R) equal to the arc of the outer peripheral surface of the agitator shaft (11), and the clamping direction (4Y) passes through the opening center (5C) of the shaft guide mechanism (5), and the bisector (33CL) of the abutment members (33) intersects the clamping direction (4Y) and passes through the opening center (5C) of the shaft guide mechanism (5).

[0019] With the above configuration, when the left and right gripping members (4cL, 4cR) and the abutment member (33) of the shaft clamping mechanism (4) act on the agitator shaft (11) simultaneously or at different times, it is possible to position the shaft center (11C) of the misaligned agitator shaft at the center (5C) of the opening of the shaft guide mechanism (5). Since the clamping direction (4Y) of the shaft clamping mechanism (4) is preset to pass through the center (5C) of the opening of the shaft guide mechanism (5), it is possible to reliably prevent the shaft clamping mechanism (4) from failing to clamp the agitator shaft (11).

[0020] A fourth feature of the ground improvement machine of the present invention is that the storage case (34) is supported by extension rod portions (46L, 46R) extending axially from the front portion of the cylinder support mechanism (40), and the cylinder (31) is attached to the storage case (34).

[0021] In this configuration, the contact member (33) can be disposed as close as possible to the agitator shaft (11), thereby allowing the axial force of the cylinder (31) to be applied to the agitator shaft (11) efficiently.

[0022] The fifth feature of the ground improvement machine of the present invention is that the cylinder support mechanism (40) forms a plate member frame structure in which "multiple vertically elongated plate sections (41L, 41M, 41R) are connected at predetermined intervals by rectangular plate sections (42L, 42R) and L-shaped plate sections (43L, 43R)."

[0023] In the above configuration, the cylinder support mechanism (40) occupies a large proportion of the space, which is advantageous for routing hydraulic piping to the cylinder (31). [Effects of the Invention]

[0024] According to the ground improvement machine of the present invention, when the agitator shaft is replaced using the hydraulic chuck mechanism and the shaft clamping mechanism, sufficient clamping force is ensured between the shaft clamping mechanism and the agitator shaft, thereby making it possible to reliably prevent the agitator shaft from falling during the replacement operation. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is an explanatory diagram showing a soil improvement machine according to one embodiment of the present invention. FIG. [Figure 2] FIG. 2 is an explanatory diagram showing a swivel head and a reader device. [Figure 3] FIG. 4 is an explanatory diagram showing a shaft clamping mechanism. [Figure 4] FIG. 4 is an explanatory diagram showing a shaft guide mechanism. [Figure 5] FIG. 2 is a front view showing a shaft pushing mechanism according to an embodiment of the present invention. [Figure 6] FIG. 2 is a perspective view illustrating a shaft pushing mechanism according to an embodiment of the present invention. [Figure 7] FIG. 7 is an explanatory diagram showing the view of arrow A in FIG. 6. [Figure 8]10A to 10C are explanatory diagrams showing an example of the operation of the shaft pushing mechanism according to the embodiment of the present invention. [Figure 9] FIG. 1 is an explanatory diagram showing the feed stroke in the process of creating a columnar improvement body with an excavation depth of 6.9 m using a conventional soil improvement machine. [Figure 10] FIG. 1 is an explanatory diagram showing the feed stroke in the process of creating a cast-in-place improvement body with an excavation depth of 25 m using a conventional soil improvement machine. [Figure 11] FIG. 10 is an explanatory diagram showing a gap between a slide hanger and a leader rail. [Figure 12] FIG. 2 is an explanatory diagram showing the oscillation and rotation of the stirring shaft in the counterclockwise direction in the drawing, centered on the center of gravity of the swivel head. [Figure 13] 1 is an explanatory diagram showing a state in which the axis of the agitator shaft is shifted from the clamping direction of the clamp mechanism toward the vehicle body side (off-center state), and a state in which the off-center agitator shaft is gripped by a clamp piece. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0027] FIG. 1 is an explanatory diagram showing a soil improvement machine 100 according to one embodiment of the present invention.

[0028] This ground improvement machine 100 is configured to be able to stably carry out ground improvement from the surface to deep layers (for example, a depth of 25 m) by appropriately shifting the grip of a long-axis (for example, over 20 m) stirring shaft 11 used in mechanical stirring methods (GI column methods) and the like.

[0029] The configuration of this ground improvement machine 100 includes a swivel head 1 that rotates the agitation shaft 11, a leader device 2 that raises and lowers the swivel head 1 along the axial direction, a hydraulic chuck mechanism 3 that fixes the position of the agitation shaft 11 while rotating the agitation shaft 11 integrally with the swivel head 1, a shaft clamp mechanism 4 that fixes the position of the agitation shaft 11, a shaft guide mechanism 5 that prevents the agitation shaft 11 from vibrating, a leader raising and lowering cylinder 6 that swings the leader device 2 back and forth, a vehicle body 7 that houses a hydraulic pump and oil tank, a hydraulic control circuit that controls the flow of oil, an engine that drives the hydraulic pump, a fuel tank, etc., a crawler device 8 that moves the ground improvement machine 100 back and forth and left and right, and a ground The machine is comprised of outriggers 9 that press the four corners of the soil improvement machine 100 against the ground to stabilize its position, a counterweight 10 that counteracts the tipping moment that tends to tip the soil improvement machine 100 when the leader device 2 rotates and penetrates the agitator shaft 11 into the ground, an agitator shaft 11 that transmits the rotational force of the swivel head 1 to the agitator 12, the agitator 12 that mixes and agitates the solidification agent in the ground, a water swivel mechanism 13 that connects a non-rotatable hose (not shown) that pumps the solidification agent to the rotatable agitator shaft 11, a guide rod 14 that supports the water swivel mechanism 13, and a shaft push-out mechanism 30 that prevents the shaft clamping mechanism 4 from failing to clamp the agitator shaft 11. Each component will be explained below.

[0030] Fig. 2 is an explanatory diagram showing the swivel head 1 and the leader device 2. Fig. 2(a) is a front view of the swivel head 1 and the leader device 2 when the swivel head 1 is positioned below the leader device 2. Fig. 2(b) is a right side view of the swivel head 1 and the leader device 2 when the swivel head 1 is positioned below the leader device 2.

[0031] 2(a), the agitation shaft 11 is rotated by a rotation drive unit 1a, which includes a left rotation motor 1bL and a right rotation motor 1bR.

[0032] The rotation drive unit 1a has a cylindrical spindle (not shown) that transmits rotational force to the agitator shaft 11, and a drive gear (not shown) that rotates the spindle. A driven gear (not shown) that engages with the drive gear is attached to the outer circumferential surface of the spindle, and the inner circumferential surface of the spindle has a shape in which arc portions that engage with the outer circumferential surface of the agitator shaft 11 and straight portions are formed alternately.

[0033] The swivel head 1 is equipped with a left feed motor 1cL and a right feed motor 1cR that move the swivel head 1 up and down along the reader device 2. A drive gear (not shown) is attached to each of the motors 1cL and 1cR, and each drive gear is engaged (meshed) with a rack gear 2b of the reader device 2.

[0034] The swivel head 1 has a left slide hanger 1dL (not shown) and a right slide hanger 1dR (FIG. 2(b)) that engage with the left leader rail 2aL and the right leader rail 2aR of the leader device 2, respectively.

[0035] As shown in FIG. 2(b), the reader device 2 has a rack gear 2b that is provided along the axial direction (longitudinal direction) of the reader device 2 and that engages with the left feed motor 1cL and the right feed motor 1cR.

[0036] The reader device 2 is also provided with a left leader rail 2aL (not shown) and a right leader rail 2aR symmetrically for raising and lowering the swivel head 1 along the longitudinal direction.

[0037] The reader device 2 is configured so that it can be raised or lowered within a range of, for example, 0° to 90° around a swing axis 2c.

[0038] A hydraulic chuck mechanism 3 is attached coaxially with the spindle (not shown) of the rotation drive unit 1a. A detailed description of the hydraulic chuck mechanism 3 is omitted here; however, the hydraulic chuck mechanism 3 includes multiple hydraulic cylinders (not shown) and a chuck piece moving mechanism (not shown) sandwiched between the hydraulic cylinders (not shown) and disc springs (not shown). When the hydraulic cylinders (not shown) contract, the chuck piece moving mechanism (not shown) is pushed by the disc springs (not shown) to move the corresponding chuck piece (not shown) radially inward and engage with a flat portion (not shown) formed on the outer peripheral surface of the agitator shaft 11. On the other hand, when the hydraulic cylinders (not shown) expand, the chuck piece moving mechanism (not shown) is pushed by the hydraulic cylinders (not shown) to move the corresponding chuck piece (not shown) radially outward, separating it from the flat portion (not shown) of the agitator shaft 11 and releasing its grip on the agitator shaft 11.

[0039] The shaft clamp mechanism 4 and the shaft guide mechanism 5 are coaxially supported by a common bracket 4a.

[0040] The shaft clamping mechanism 4 has two cylinders for clamping the agitation shaft 11.

[0041] 2(a), a left guide rod 14L and a right guide rod 14R are symmetrically attached to the rotary drive unit 1a via a connecting plate 15. A water swivel mechanism 13 is attached to the connecting plate 15.

[0042] Figure 3 is an explanatory diagram showing the shaft clamping mechanism 4. Figure 3(a) shows a state in which the shaft clamping mechanism 4 is not clamping the agitator shaft 11. Figure 3(b) shows a state in which the shaft clamp 4 is clamping the agitator shaft 11. As shown in Figure 3(a), the left and right clamp arms 4aL, 4aR are configured to be swingable and are closed by two lock pins 4LP, 4LP via a lock plate 4LB. Each clamp arm 4aL, 4aR has a clamp cylinder 4bL, 4bR, respectively. Here, if the imaginary axis connecting the rod centers of the left and right clamp cylinders 4bL, 4bR is defined as the clamp Y-axis 4Y, and the axis of symmetry of the shaft clamp mechanism 4 is defined as the clamp X-axis 4X, the intersection of the clamp Y-axis 4Y and the clamp X-axis 4X is defined as the clamp opening center 4C.

[0043] The left and right clamp arms 4aL and 4aR are formed with arcuate portions 4aLR and 4aRR, respectively. Each arcuate portion 4aLR and 4aRR is part of a clamp inner circumferential circle 4iC whose center is the clamp opening center 4C. The diameter of the clamp inner circumferential circle 4iC is larger than the maximum outer diameter of the agitator shaft 11.

[0044] As shown in Figure 3(b), the left and right clamp pieces 4cL, 4cR protrude radially inward from the arc-shaped portions 4aLR, 4aRR. The contact surfaces 4cLa, 4cRa of the left and right clamp pieces 4cL, 4cR each have a radius of curvature R equal to the arc of the outer circumferential surface of the stirring shaft 11.

[0045] Therefore, when the axis 11C of the agitator shaft is positioned on the clamp Y axis 4Y, by operating the left and right clamp cylinders 4bL, 4bR to clamp the agitator shaft 11 with the left and right clamp pieces 4cL, 4cR, the axis 11C of the agitator shaft is positioned at the clamp opening center 4C, and the position of the agitator shaft 11 is fixed by the left and right clamp pieces 4cL, 4cR.

[0046] Figure 4 is an explanatory diagram showing the shaft guide mechanism 5. Figure 4(a) shows a state in which the agitator shaft 11 is not guided by the shaft guide mechanism 5. Figure 4(b) shows a state in which the agitator shaft 11 is guided by the shaft guide mechanism 5.

[0047] As shown in FIG. 4(a), the left and right guide arms 5aL, 5aR are configured to be swingable. When the left and right guide arms 5aL, 5aR are closed by the lock pin 5L, a guide inner circumference circle 5iC with a diameter φD is formed on the inside. Here, if the axis of symmetry of the axis guide mechanism 5 is the guide X-axis 5X, the guide X-axis 5X passes through the center 5C of the guide inner circumference circle. Furthermore, a virtual axis that is perpendicular to the guide axis 5X and passes through the center 5C of the guide inner circumference circle is defined as the guide Y-axis 5Y.

[0048] In this embodiment, the guide inner circumference center 5C and the clamp opening center 4C are located coaxially. Similarly, the guide X-axis 5X and the clamp X-axis 4X also coincide in a plane (two-dimensionally). Similarly, the guide Y-axis 5Y and the clamp Y-axis 4Y also coincide in a plane (two-dimensionally).

[0049] As shown in FIG. 4(b), the maximum outer diameter of the agitator shaft 11 is smaller than the diameter φD of the guide inner circumference. Therefore, a gap is formed between the guide inner circumference 5iC and the agitator shaft 11. For example, if the swivel head 1 tilts forward due to a gap between the left and right leader rails 2aL, 2aR (FIG. 2) and the left and right slide hangers 1dL, 1dR (FIG. 2), the agitator shaft 11 will move rearward. As a result, a misalignment occurs in which the axis center 11C of the agitator shaft deviates from the clamping direction of the shaft clamping mechanism 4 (guide Y axis 5Y or clamp Y axis 4Y).

[0050] When a misaligned agitator shaft 11 is clamped by the shaft clamping mechanism 4, it becomes impossible to ensure sufficient gripping force between the left and right clamp pieces 4cL, 4cR of the shaft clamping mechanism 4 and the outer circumferential surface of the agitator shaft 11, and in the worst case scenario, the agitator shaft 11 may fall from the shaft clamping mechanism 4, thereby damaging the guide rod 14 and the water swivel mechanism 13. For this reason, the ground improvement machine 100 of the present invention is provided with a shaft pushing mechanism 30 below the shaft guide mechanism 5 to prevent the agitator shaft 11 from falling from the shaft clamping mechanism 4. This shaft pushing mechanism 30 will be described below.

[0051] 5 to 7 are explanatory views showing a shaft pushing mechanism 30 according to one embodiment of the present invention. Fig. 5 is a front view of the shaft pushing mechanism 30. Fig. 6 is a perspective view of the shaft pushing mechanism 30 as seen from the bottom. Fig. 7 is a view taken along the arrow A in Fig. 6.

[0052] 5, the shaft pushing mechanism 30 is configured to include a cylinder 31 that moves a rod 32 back and forth along the axial direction, a push piece 33 that is attached to the tip of the rod 32 and abuts against the outer circumferential surface of the agitator shaft 11, a storage case 34 that stores the push piece 33, and a shaft pushing mechanism bracket 40 that supports the cylinder 31. Each component will be described in further detail below.

[0053] The cylinder 31 can be, for example, a two-port (port A, port B) hydraulic cylinder. For example, when hydraulic oil flows into port A and flows out from port B, the rod 32 moves forward. On the other hand, when hydraulic oil flows out from port A and into port B, the rod 32 moves rearward. When the flow of hydraulic oil stops at ports A and B, the movement of the rod 32 stops.

[0054] The push piece 33 has a contact surface 33a (FIG. 8) with a radius of curvature R equal to the outer circumferential arc of the agitator shaft 11. The push piece 33 is fixed to the rod 32 with a bolt. As will be described in detail later with reference to FIG. 8, the left and right clamp pieces 4cL, 4cR of the shaft clamping mechanism 4 also each have a radius of curvature R equal to the outer circumferential arc of the agitator shaft 11. Therefore, when the left and right clamp pieces 4cL, 4cR clamp the agitator shaft 11 from both sides, when the push piece 33 pushes out the agitator shaft 11, the shaft center 11C of the agitator shaft is positioned at the guide inner circumferential center 5C. This ensures sufficient clamping force between the left and right clamp pieces 4cL, 4cR of the shaft clamping mechanism 4 and the agitator shaft 11. This prevents the agitator shaft 11 from falling off during the clamping operation.

[0055] The storage case 34 stores the push piece 33 inside so that it does not interfere with the agitator shaft 11 when the push piece 33 is not in use. It is also positioned forward by the left and right rectangular pillar extension rod portions 46L, 46R. Therefore, by attaching the cylinder 31 to the storage case 34, it becomes possible to push out the agitator shaft 11 with the push piece 33 from a nearby position.

[0056] The bracket 40 for the shaft pushing-out mechanism is attached to the lower end of the shaft guide mechanism 5 via a front joining plate portion 44F with fasteners, and is also attached to the lower end of the leader device 2 via a rear joining plate portion 44R with fasteners. The middle joining plate portion 44M is joined to a common bracket 4a (FIG. 2) of the shaft clamp mechanism 4 and the shaft guide mechanism 5. Details of the bracket 40 for the shaft pushing-out mechanism will be described later with reference to FIG. 6.

[0057] As shown in FIG. 6, the bracket 40 for the shaft pushing-out mechanism has a plate member frame structure in which "a vertically long left side plate portion 41L, a vertically long center plate portion 41M, and a vertically long right side plate portion 41R are connected at a predetermined distance by a left connecting plate portion 42L and a right connecting plate portion 42R, respectively, and are further connected by a left L-shaped connecting plate portion 43L and a right L-shaped connecting plate portion 43R, respectively."

[0058] A front joining plate portion 44F, a middle joining plate portion 44M, and a rear joining plate portion 44R are attached to the upper surfaces of the vertically long left side plate portion 41L, the vertically long center plate portion 41M, and the vertically long right side plate portion 41R, respectively.

[0059] The front joining plate portion 44F has two through holes 44Fa through which fasteners can be passed. The rear joining plate portion 44R has six through holes 44Ra (FIG. 5), three on each side, through which fasteners can be passed. Left and right female thread plate portions 47L and 47R are attached concentrically with the through holes 44Ra.

[0060] Further, the left side plate portion 41L and the right side plate portion 41R are respectively formed with a left auxiliary plate portion 45L and a right auxiliary plate portion 45R that support the rear joining plate portion 44R.

[0061] The left L-shaped connecting plate 43L and the right L-shaped connecting plate 43R are respectively attached with fasteners to a left rectangular column extension rod 46L and a right rectangular column cylindrical rod 46R. The storage case 34 is attached with fasteners to the other ends of the left rectangular column extension rod 46L and the right rectangular column cylindrical rod 46R.

[0062] As shown in Figure 7, a right-hand female thread block 34aR is attached to the back of the storage case 34. The right-hand female thread block 34aR engages with a fastener inserted from the underside of the right rectangular column extension rod portion 46R. A left-hand female thread block 34aL (Figure 6) is also attached to the left side and engages with a fastener inserted from the underside of the left rectangular column extension rod portion 46L. This allows the storage case 34, and therefore the cylinder 31, to be stably fixed to the left and right rectangular column extension rod portions 46L, 46R.

[0063] 8 is an explanatory diagram showing an example of the operation of the shaft push-out mechanism 30 according to one embodiment of the present invention. For convenience of explanation, it is assumed that the clamp Y-axis 4Y of the shaft crank mechanism 4 passes through the center 5C of the guide inner circumference of the shaft guide mechanism 5, and that the push piece bisector 33CL also passes through the center 5C of the guide inner circumference. It is also assumed that the contact surfaces 4cLa, 4cRa of the left and right clamp pieces 4cL, 4cR and the contact surface 33a of the push piece 33 each have a radius of curvature R equal to the outer circumferential arc of the agitator shaft 11.

[0064] 8(a), when the swivel head 1 tilts forward, the agitator shaft 11 moves toward the rear of the guide inner circumference circle 5iC. As a result, the axis 11C of the agitator shaft becomes misaligned with the clamping direction (clamp Y axis 4Y) of the shaft clamping mechanism 4.

[0065] 8(b), when the left clamp piece 4cL, right clamp piece 4cR, and push piece 33 are applied to the outer peripheral surface of the misaligned agitator shaft 11, the axis 11C of the agitator shaft is positioned at the center 5C of the guide inner circumference. In this case, the push piece bisector 33CL and the clamp Y axis 4Y do not necessarily have to be perpendicular to each other; they may intersect at an angle greater than 0° and less than 180°.

[0066] Furthermore, the radius of curvature of the contact surface 33a of the push piece 33 does not necessarily have to be equal to the outer circumferential arc of the stirring shaft 11, and may be, for example, a flat surface. [Explanation of symbols]

[0067] 1 Swivel head (rotation drive device) 1a Rotation drive unit 1bL Left rotation motor 1bR Right rotation motor 1cL left motor for feed 1cR Right motor for feed 1dL left slide hanger 1dR Right Slide Hanger 2. Reader device (lifting device) 2aL left leader rail 2aR Right leader rail 2b Rack gear 2c Oscillating shaft 3 Hydraulic chuck mechanism 4-axis clamping mechanism 4C Clamp opening center 4a Common bracket 4aL Left clamp arm 4aLR Arc section 4aR Right Clamp Arm 4aRR Arc section 4bL Left clamp cylinder 4bR Right Clamp Cylinder 4cL Left clamp piece (gripping member) 4cR Right clamp piece (gripping member) 4iC Clamp inner circumference 4LP lock pin 4LB Lock Plate 4X clamp X axis 4Y Clamp Y axis 5-axis guide mechanism 5aL left guide arm 5aR Right Guide Arm 5C Guide inner circumference center (opening center) 5iC guide inner circumference 5X Guide X-axis 5Y Guide Y axis 6 Leader raising / lowering cylinder 7 Body 8 Crawler device 9 Outrigger 10 Counterweight 11 Agitator shaft 11C Agitator shaft center 30 Axle extrusion mechanism 31 cylinders 32 Rod 33 Push piece (contact part) 34 Storage Case 34aL Left-hand female thread block 34aR Right-Hand Female Thread Block 40 Bracket for shaft push-out mechanism (cylinder support mechanism) 41L Left side plate (vertical plate) 41R Right side plate (vertical plate) 41M Center plate (vertical plate) 42L Left connecting plate (rectangular plate) 42R Right connecting plate (rectangular plate) 43L Left L-shaped connecting plate 43R Right L-shaped connecting plate 44F Front joint plate 44Fa through hole 44M Middle joint plate 44R rear joining plate 44Ra through hole 45L Left auxiliary plate 45R Right auxiliary plate 46L Left square column extension rod part (extension rod part) 46R Right Square Pillar Extension Rod (Extension Rod) 47L Left female thread plate 47R Right-hand female thread plate 100 Ground improvement machine

Claims

1. a rotation drive device (1) that rotates an agitation shaft (11); an elevator (2) for raising and lowering the rotation drive device (1) in a predetermined direction; a hydraulic chuck mechanism (3) for rotatably fixing the position of the stirring shaft (11) relative to the rotation drive device (1); a shaft clamping mechanism (4) for fixing the position of the stirring shaft (11); A ground improvement machine equipped with an axial guide mechanism (5) that defines the axial center (11C) direction of the stirring shaft (11), The lifting device (2) has a shaft pushing mechanism (30) that can push the agitating shaft (11) in a direction that intersects with the clamping direction (4Y) of the shaft clamping mechanism (4) relative to the agitating shaft (11) and toward the opening center (5C) of the shaft guide mechanism (5). A ground improvement machine characterized by:

2. The soil improvement machine according to claim 1, The axial pushing mechanism (30) includes a cylinder (31) that moves a rod (32) back and forth along the axial direction, a contact member (33) that is attached to the tip of the rod (32) and contacts the outer circumferential surface of the stirring shaft (11), a storage case (34) that stores the contact member (33), and a cylinder support mechanism (40) that supports the cylinder (31). A ground improvement machine characterized by:

3. The soil improvement machine according to claim 2, Among the left and right gripping members (4cL, 4cR) of the shaft clamping mechanism (4) and the abutting member (33) of the shaft pushing mechanism (30), at least the left and right gripping members (4cL, 4cR) have surfaces (4cLa, 4cRa) that come into contact with the agitating shaft (11) and have a radius of curvature (R) equal to the arc of the outer peripheral surface of the agitating shaft (11), respectively; and The clamping direction (4Y) passes through the opening center (5C) of the shaft guide mechanism (5), and The bisector (33CL) of the contact member (33) intersects with the clamping direction (4Y) and passes through the opening center (5C) of the shaft guide mechanism (5). A ground improvement machine characterized by:

4. The soil improvement machine according to claim 2, The storage case (34) is supported by extension rod portions (46L, 46R) extending axially from a front portion of the cylinder support mechanism (40), The cylinder (31) is attached to the storage case (34). A ground improvement machine characterized by:

5. The soil improvement machine according to claim 2, The cylinder support mechanism (40) has a plate member frame structure in which "plurality of vertically elongated plate portions (41L, 41M, 41R) are connected at predetermined intervals by rectangular plate portions (42L, 42R) and L-shaped plate portions (43L, 43R)." A ground improvement machine characterized by:

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