Caisson type pile excavator

Abstract

To suppress interference between a rope to be detected for slackness and a slackness detection device.SOLUTION: A caisson type pile excavator 1 includes a first lifting sheave 19 and a first opening / closing sheave 21 that move in the length direction of an arm 10, a second lifting sheave 23 and a second opening / closing sheave 30, a lifting rope 38 wound around the first lifting sheave 19 and the second lifting sheave 23, an opening / closing rope 39 wound around the first opening / closing sheave 21 and the second opening / closing sheave 30, and slackness detection device 47 (62) that detects the slackness of the detected rope among the lifting rope 38 and the opening / closing rope 39. The slackness detection device 47 (62) is arranged inside a lifting rope path 38C formed by the lifting rope 38 wound around the first lifting sheave 19 and the second lifting sheave 23, and / or it is arranged inside an opening / closing rope path 39C formed by the opening / closing rope 39 wound around the first opening / closing sheave 21 and the second opening / closing sheave 30.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a deep foundation excavator suitable for use in excavating a vertical shaft. [Background technology]

[0002] A deep foundation excavator has been proposed that excavates a shaft in the ground and lifts and removes the excavated soil and sand. The arm of the deep foundation excavator is fitted with a clamshell bucket via a lifting rope and an opening / closing rope. This deep foundation excavator is provided with a bucket lifting / opening device, and the bucket lifting / opening device lifts and opens and closes the clamshell bucket to excavate a shaft in the ground.

[0003] When excavating a shaft with a clamshell bucket, the lifting rope and the opening and closing rope are let out to lower the clamshell bucket and land it on the ground. The clamshell bucket is then closed while sinking into the ground under its own weight, allowing the soil to be excavated. The lifting rope and the opening and closing rope are then wound up to raise the clamshell bucket, and the excavated soil is discharged onto the bed of a dump truck or the like.

[0004] Here, if the lifting rope and the opening and closing rope become excessively loose when the clamshell bucket lands on the ground, time is wasted when winding up the lifting rope and the opening and closing rope to lift the clamshell bucket after excavating the soil. For this reason, it is necessary to detect the looseness of the lifting rope, etc., stop the lowering operation of the clamshell bucket, and quickly transition to the lifting operation. As a device for detecting such a looseness of the rope, a looseness detection device has been proposed that has a coil spring that is provided at the end of the detection target rope to be detected and expands and contracts according to the tension acting on the detection target rope, and a sensor that detects the looseness of the detection target rope based on the displacement of the end of the detection target rope, etc. (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2004-176391 A [Patent Document 2] Japanese Patent Application Publication No. 8-134878 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in order for a deep foundation excavator to excavate a shaft by lowering a clamshell bucket deep into the ground, the lifting rope and the opening and closing rope are each wound around multiple sheaves. Since the multiple sheaves are arranged adjacent to each other in the axial direction of the rotation center, the spacing between adjacent lifting ropes wound around the multiple sheaves and the spacing between adjacent opening and closing ropes are very narrow.

[0007] In contrast, the slack detection devices according to Patent Documents 1 and 2 have a shape larger than the rope diameter of the detected rope. Therefore, when the slack detection devices according to Patent Documents 1 and 2 are installed on the ends of the detected ropes, of which the slack should be detected among the lifting ropes and the opening and closing ropes mounted on a deep foundation excavator, there is a problem that the slack detection devices interfere with the adjacent detected ropes, causing damage to the detected ropes.

[0008] An object of the present invention is to provide a deep foundation excavator that is capable of suppressing interference between the rope to be detected for slack and the slack detection device. [Means for solving the problem]

[0009] The present invention comprises an arm provided on a self-propelled vehicle body, a clamshell bucket provided on the arm so as to be able to rise and fall, and a bucket lifting and opening / closing device provided on the arm for lifting and lowering the clamshell bucket and opening and closing the clamshell bucket, the bucket lifting and opening / closing device comprising a first lifting sheave and a first opening / closing sheave provided on the arm and moved in the length direction of the arm by a lifting cylinder, a second lifting sheave and a second opening / closing sheave provided on the arm, respectively, spaced apart from the first lifting sheave and the first opening / closing sheave, and a wire wound around the first lifting sheave and the second lifting sheave, one end of which is attached to the arm and the other end of which is attached to the clamshell bucket. the first and second opening / closing sheaves, one end of which is attached to the arm and the other end to the clamshell bucket; and a slack detection device that is provided at one end of the lifting rope and the open / close rope that is the target of detection and detects slack in the target rope.The deep foundation excavator is characterized in that the slack detection device is positioned inside the annular lifting rope path formed by the lifting rope wound around the first lifting sheave and the second lifting sheave, and / or inside the annular opening / closing rope path formed by the opening / closing rope wound around the first and second opening / closing sheaves. Effect of the Invention

[0010] According to the present invention, when the rope to be detected is an ascent rope, the slack detection device can be arranged inside the annular ascent rope path formed by the ascent rope. Therefore, even if a slack detection device larger than the rope diameter is provided at one end of the ascent rope, interference between the slack detection device and the ascent rope can be prevented. Similarly, when the rope to be detected is an opening / closing rope, the slack detection device can be arranged inside the annular opening / closing rope path formed by the opening / closing rope. Therefore, even if a slack detection device larger than the rope diameter is provided at one end of the opening / closing rope, interference between the slack detection device and the opening / closing rope can be prevented. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a left side view showing a deep foundation excavator according to an embodiment of the present invention. [Diagram 2] FIG. 4 is a left side view showing the bucket lifting and opening / closing device. [Diagram 3] FIG. 2 is a plan view showing the bucket lifting and opening / closing device. [Figure 4] FIG. 4 is a right side view showing the bucket lifting and opening / closing device. [Diagram 5] FIG. [Figure 6] FIG. 2 is a perspective view showing a slack detection device, a lifting rope, etc. [Figure 7] FIG. 4 is an enlarged left side view showing the loosening detection device. [Figure 8] 8 is a bottom view of the loosening detection device as viewed from the direction of arrows VIII-VIII in FIG. 7. [Figure 9] 9 is a cross-sectional view of the loosening detection device as viewed from the direction of arrows IX-IX in FIG. 7. [Figure 10] 9 is a cross-sectional view of the loosening detection device as seen from the direction of the arrow XX in FIG. 8. [Figure 11] FIG. 13 is a right side view of a bucket lifting and opening / closing device showing a modified example in which no slack detection device is provided at one end of the opening / closing rope. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a deep foundation excavator according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the embodiment, the length direction of the arm is the front-rear direction, and the direction perpendicular to the length direction of the arm is the left-right direction.

[0013] In Fig. 1, the deep foundation excavator 1 is manufactured based on, for example, a crawler-type hydraulic excavator. The deep foundation excavator 1 is composed of a self-propelled crawler-type lower traveling body 2, an upper rotating body 3 rotatably mounted on the lower traveling body 2, and a working device 5 (described later) provided on the upper rotating body 3. The lower traveling body 2 and the upper rotating body 3 constitute the vehicle body of the deep foundation excavator 1.

[0014] The cab 4 is provided on the left front side of the upper rotating body 3. The cab 4 defines a driver's compartment, and an operator who operates the deep foundation excavator 1 sits in the cab 4. A driver's seat 4A where the operator sits is provided inside the cab 4, and around the driver's seat 4A, operating devices (not shown) for operating the traveling operation of the lower traveling body 2, the rotating operation of the upper rotating body 3, and the working device 5 are provided.

[0015] The working device 5 includes a boom 6 that is provided on the upper rotating body 3 so as to be rotatable in the vertical direction, an arm 10 described below, a clamshell bucket 9, and a bucket lifting / opening / closing device 17. A boom cylinder 7 is provided between the upper rotating body 3 and the boom 6, and the boom 6 rotates relative to the upper rotating body 3 in response to the extension and retraction of the boom cylinder 7. An arm cylinder 8 is provided between the boom 6 and the arm 10, and the arm 10 rotates relative to the boom 6 in response to the extension and retraction of the arm cylinder 8.

[0016] The clamshell bucket 9 is suspended from the front end of the arm 10 by a lifting rope 38 described later so as to be liftable and lowerable. The clamshell bucket 9 has a bucket support part 9A, a pair of buckets 9B provided on the lower side of the bucket support part 9A so as to be able to open and close, a connecting bracket 9C to which the pair of buckets 9B are rotatably connected, and a pair of opening and closing arms 9D connecting the bucket support part 9A and the pair of buckets 9B. The bucket support part 9A is provided with a plurality of upper sheaves 9E, and the connecting bracket 9C is provided with a plurality of lower sheaves 9F that face the upper sheaves 9E in the up-down direction.

[0017] The other end 38B of the lifting rope 38 is attached to the bucket support portion 9A of the clamshell bucket 9. An opening / closing rope 39, which will be described later, is wound alternately around the upper sheave 9E and the lower sheave 9F of the clamshell bucket 9, and the other end 39B of the opening / closing rope 39 is attached to the bucket support portion 9A of the clamshell bucket 9.

[0018] The arm 10 is rotatably provided at the tip of the boom 6. As shown in Fig. 5, the arm 10 is configured to be separable and includes an arm body 11 formed of a hollow cylinder and extending in the front-rear direction, a pair of guide arms 12, 13 detachably provided on the rear side of the arm body 11, and a sheave mounting member 14 movably attached to the guide arms 12, 13.

[0019] The arm body 11 is the base of the arm 10, and is formed as a square cylinder having a rectangular cross section. The arm body 11 is surrounded by a left side plate 11A and a right side plate 11B that face each other in a direction (left-right direction) perpendicular to the length direction (front-rear direction) of the arm 10, an upper plate 11C that connects the upper ends of the left side plate 11A and the right side plate 11B, and a lower plate 11D that connects the lower ends of the left side plate 11A and the right side plate 11B. Here, the left side plate 11A of the arm body 11 is disposed on the side of the driver's seat 4A provided in the cab 4 of the upper rotating body 3, and is a surface that is easy to see (highly visible) for the operator sitting in the driver's seat 4A.

[0020] The distance between the left side plate 11A and the right side plate 11B is set smaller than the distance between the upper plate 11C and the lower plate 11D. The front end 11E of the arm body 11 is closed, and the rear end 11F of the arm body 11 is an open end. A step surface 11G is formed in a portion of the upper plate 11C of the arm body 11 that is located forward of the center in the front-rear direction, and has a lower height (distance from the lower plate 11D) than a portion located rearward of the center. An intermediate guide sheave 37, which will be described later, is provided on the step surface 11G. A boom mounting bracket 11H and a cylinder mounting bracket 11J are provided on the lower plate 11D of the arm body 11. The boom mounting bracket 11H is rotatably connected to the tip of the boom 6 via a connecting pin 11K (see FIG. 1). The cylinder mounting bracket 11J is pin-connected to the tip of the arm cylinder 8, the base end of which is attached to the boom 6. Therefore, the arm body 11 rotates in the front-rear direction or the up-down direction about the connecting pin 11K in response to the extension and retraction movement of the arm cylinder 8.

[0021] At the rear end 11F of the left side plate 11A and the right side plate 11B, two pin insertion holes 11L, 11M are formed, which are vertically spaced apart and penetrate in the left-right direction. The connecting pins 12B, 13B described later are inserted into these pin insertion holes 11L, 11M. In addition, the trunnion pin 18D described later is inserted into the left side plate 11A and the right side plate 11B forward of the pin insertion holes 11L, 11M. Meanwhile, the guide sheave support shaft 32 described later is fixed to the front end 11E of the left side plate 11A. The second lift sheave shaft 24 described later is fixed to the middle part of the left side plate 11A in the front-rear direction.

[0022] The guide arms 12 and 13 are detachably attached to the rear side of the arm body 11 in a pair in the up-down direction. The guide arms 12 and 13 are each formed as a rectangular cylinder having a rectangular cross section and extend in the front-rear direction. Cylindrical portions 12A and 13A extending in the left-right direction are fixed to the front ends of the guide arms 12 and 13, respectively. A connecting pin 12B is inserted into the inner periphery of the cylindrical portion 12A of the guide arm 12, and both ends of the connecting pin 12B are inserted into the pin insertion hole 11L of the arm body 11. A connecting pin 13B is inserted into the inner periphery of the cylindrical portion 13A of the guide arm 13, and both ends of the connecting pin 13B are inserted into the pin insertion hole 11M of the arm body 11. Meanwhile, the rear ends of the guide arms 12 and 13 are connected via a connecting member 13C. As a result, the guide arms 12 and 13 extend rearward from the rear end 11F of the arm body 11 while maintaining a constant gap therebetween in the vertical direction.

[0023] The sheave mounting member 14 is movably attached to the pair of guide arms 12, 13, and constitutes a part of the arm 10. With a first lifting sheave 19 and a first opening / closing sheave 21 (described later) attached to the sheave mounting member 14, the sheave mounting member 14 moves in the front-rear direction along the guide arms 12, 13. The sheave mounting member 14 is formed as a cylinder having a rectangular cross-sectional shape similar to that of the arm body 11, and surrounds the guide arms 12, 13 from the outside. That is, the sheave mounting member 14 is formed as a short cylinder (frame) surrounded by a left side plate 14A, a right side plate 14B, an upper plate 14C, and a lower plate 14D.

[0024] Pin insertion holes 14E penetrating in the left-right direction are formed concentrically in the front portions of the left and right plates 14A and 14B constituting the sheave mounting member 14. A rod mounting pin 18F, which will be described later, is inserted into these two pin insertion holes 14E. A left shaft mounting hole 14F penetrating in the left-right direction is formed in the center of the left plate 14A constituting the sheave mounting member 14, and a right shaft mounting hole 14G penetrating in the left-right direction is formed in the center of the right plate 14B. A first lifting sheave shaft 20, which will be described later, is attached to the left shaft mounting hole 14F, and a first opening / closing sheave shaft 22, which will be described later, is attached to the right shaft mounting hole 14G.

[0025] A slide plate 15 is provided between the inner peripheral surfaces of the left side plate 14A, right side plate 14B and upper plate 14C of the sheave mounting member 14 and the guide arm 12, respectively, and the slide plate 15 is in slidable contact with the guide arm 12. A slide plate 16 is provided between the inner peripheral surfaces of the left side plate 14A, right side plate 14B and lower plate 14D of the sheave mounting member 14 and the guide arm 13, respectively, and the slide plate 16 is in slidable contact with the guide arm 13. These slide plates 15, 16 are fixed to the sheave mounting member 14 using bolts or the like, and allow the sheave mounting member 14 to move (slide) smoothly relative to the guide arms 12, 13.

[0026] Next, the bucket lifting / opening / closing device 17 used in this embodiment will be described.

[0027] The bucket lifting / opening device 17 is provided on the arm 10. The bucket lifting / opening device 17 performs various operations including lifting / lowering and opening / closing of the clamshell bucket 9. The bucket lifting / opening device 17 includes a lifting cylinder 18, a first lifting sheave 19, a first opening / closing sheave 21, a second lifting / lowering sheave 23, a second opening / closing sheave 30, an opening / closing cylinder 31, an intermediate guide sheave 37, a lifting rope 38, an opening / closing rope 39, a slack adjustment sheave 45, and a slack adjustment cylinder 46, which will be described later.

[0028] The lifting cylinder 18 is provided in the arm body 11 constituting the arm 10, and extends along the length direction (front-rear direction) of the arm body 11. The lifting cylinder 18 lifts and lowers the clamshell bucket 9 by extending or retracting in response to the operation of an operating device provided in the cab 4. The lifting cylinder 18 has a tube 18A, a piston (not shown) inserted into the tube 18A, and a rod 18B whose base end is attached to the piston and whose tip protrudes from the tube 18A.

[0029] A mounting flange 18C is fixed to the tube 18A, and two trunnion pins 18D inserted through the left side plate 11A and right side plate 11B of the arm body 11 are fitted into the mounting flange 18C. This allows the tube 18A of the lifting cylinder 18 to be supported so as to be swingable about the trunnion pins 18D relative to the arm body 11. Meanwhile, a cylindrical mounting eye 18E is provided at the tip of the rod 18B of the lifting cylinder 18, and a rod mounting pin 18F is inserted into the pin insertion hole 14E of the sheave mounting member 14 and the mounting eye 18E.

[0030] In this manner, the tube 18A of the lift cylinder 18 is attached to the arm body 11, and the rod 18B is attached to the sheave mounting member 14. Therefore, by extending and contracting the lift cylinder 18, the sheave mounting member 14 moves in the front-rear direction along the guide arms 12, 13.

[0031] The first lifting sheave 19 is attached to the outer surface of the left side plate 14A constituting the sheave mounting member 14 via a first lifting sheave shaft 20. The base end of the first lifting sheave shaft 20 is fixed to the left shaft mounting hole 14F of the sheave mounting member 14 (left side plate 14A), and the tip end protrudes to the left side from the sheave mounting member 14. A plurality of first lifting sheaves 19 (e.g., five) are provided lined up in the axial direction of the first lifting sheave shaft 20, and are supported relative to the sheave mounting member 14 so as to be rotatable about the first lifting sheave shaft 20.

[0032] The first opening and closing sheave 21 is attached to the outer surface of the right side plate 14B constituting the sheave mounting member 14 via a first opening and closing sheave shaft 22. The base end of the first opening and closing sheave shaft 22 is fixed to the right shaft mounting hole 14G of the sheave mounting member 14 (right side plate 14B), and the tip end protrudes to the right side from the sheave mounting member 14. A plurality of first opening and closing sheaves 21 (e.g., five) are provided lined up in the axial direction of the first opening and closing sheave shaft 22, and are supported by the sheave mounting member 14 to be rotatable around the first opening and closing sheave shaft 22.

[0033] The second lifting sheave 23 is provided on the arm body 11 at a distance from the first lifting sheave 19. The second lifting sheave 23 is attached to the outer surface of the left side plate 11A constituting the arm body 11 via the second lifting sheave shaft 24. The base end of the second lifting sheave shaft 24 is fixed to the left side plate 11A of the arm body 11, and the tip end protrudes leftward from the arm body 11. The second lifting sheaves 23 are provided in a plurality (for example, four) arranged in the axial direction of the second lifting sheave shaft 24, and are supported on the arm body 11 so as to be rotatable about the second lifting sheave shaft 24. Therefore, as the sheave mounting member 14 moves in response to the extension and contraction of the lifting cylinder 18, the first lifting sheave 19 attached to the sheave mounting member 14 approaches or moves away from the second lifting sheave 23. A lifting rope 38 is wound around the first lifting sheave 19 and the second lifting sheave 23.

[0034] The opening / closing sheave moving mechanism 25 is provided on the right side plate 11B, located at the middle in the front-rear direction of the arm body 11. The opening / closing sheave moving mechanism 25 supports the second opening / closing sheave 30 so that it can move in the front-rear direction. As shown in Fig. 3, the opening / closing sheave moving mechanism 25 includes a guide rail 26, a pair of slide members 27, a frame member 28, and a second opening / closing sheave shaft 29.

[0035] The guide rail 26 is made of a block body with a T-shaped cross section extending in the front-rear direction, and is fixed to the right side plate 11B of the arm body 11. A pair of slide members 27 are paired in the up-down direction with the guide rail 26 in between, and each slides 27 is slidably engaged with the guide rail 26. The frame member 28 is attached to the pair of slide members 27 using bolts or the like. A rod attachment pin 28A extending in the left-right direction is attached to the frame member 28, and an attachment eye 31D of the opening-closing cylinder 31 described later is attached to the rod attachment pin 28A. In addition, a second opening-closing sheave shaft 29 extending in the left-right direction adjacent to the rod attachment pin 28A is attached to the frame member 28.

[0036] The second opening / closing sheave 30 is rotatably attached to the second opening / closing sheave shaft 29 of the opening / closing sheave moving mechanism 25. That is, the second opening / closing sheave 30 is provided on the outer surface of the right side plate 11B constituting the arm body 11 so as to be movable in the front-rear direction via the opening / closing sheave moving mechanism 25. A plurality of second opening / closing sheaves 30 (for example, four) are provided lined up in the axial direction of the second opening / closing sheave shaft 29 provided in the opening / closing sheave moving mechanism 25, and are supported rotatably around the second opening / closing sheave shaft 29 relative to the arm body 11.

[0037] The opening / closing cylinder 31 is provided on the right side plate 11B at the rear side (rear end 11F side) of the arm body 11. The opening / closing cylinder 31 extends in the front-rear direction and moves the second opening / closing sheave 30 closer to or farther from the first opening / closing sheave 21. The opening / closing cylinder 31 has a tube 31A, a piston (not shown) inserted into the tube 31A, and a rod 31B whose base end is attached to the piston and whose tip end protrudes from the tube 31A. The bottom side of the tube 31A is attached to the rear end 11F side of the right side plate 11B of the arm body 11 via a bracket 31C. A cylindrical mounting eye 31D is provided at the tip of the rod 31B, and the mounting eye 31D is attached to the frame member 28 of the opening / closing sheave moving mechanism 25 via a rod mounting pin 28A. Therefore, the second opening / closing sheave 30 attached to the opening / closing sheave moving mechanism 25 moves in the front-rear direction in response to the expansion and contraction of the opening / closing cylinder 31 , and approaches or moves away from the first opening / closing sheave 21 .

[0038] The guide sheave support shaft 32 is provided on the left side plate 11A located on the front end 11E side of the arm body 11. The base end of the guide sheave support shaft 32 is fixed to the left side plate 11A, and the tip of the guide sheave support shaft 32 protrudes leftward from the left side plate 11A. The guide sheave support shaft 32 rotatably supports the lift guide sheave 33 and the opening / closing guide sheave 34.

[0039] The lift guide sheave 33 and the opening / closing guide sheave 34 are provided on the left side plate 11A of the arm body 11 via the guide sheave support shaft 32. The lift guide sheave 33 and the opening / closing guide sheave 34 have the same diameter. The lift guide sheave 33 guides the lift rope 38 wound around the first lift sheave 19 and the second lift sheave 23 to the clamshell bucket 9. The opening / closing guide sheave 34 guides the opening / closing rope 39 wound around the first opening / closing sheave 21, the second opening / closing sheave 30, and the intermediate guide sheave 37 and the slack adjustment sheave 45 described later to the clamshell bucket 9. As a result, as shown in FIG. 1, for example, while the arm 10 is held horizontally to the ground, the clamshell bucket 9 can be raised and lowered in the vertical direction using the lift rope 38 wound around the lift guide sheave 33 arranged at the front end of the arm 10.

[0040] Here, the lifting / lowering guide sheave 33 and the opening / closing guide sheave 34 are disposed on the front end 11E side of the left side panel 11A of the arm body 11, which is highly visible to the operator sitting in the driver's seat 4A. This allows the operator to operate the bucket lifting / opening device 17 while visually checking the state of the lifting / lowering rope 38 and the opening / closing rope 39 attached to the clamshell bucket 9. Furthermore, by making the lifting / lowering guide sheave 33 and the opening / closing guide sheave 34 have the same diameter, the distance A in the front-rear direction between the lifting / lowering rope 38 and the opening / closing rope 39 near the front end 11E of the arm body 11 can be made as small as possible (see FIG. 1). This creates the distance A in the front-rear direction between the lifting / lowering rope 38 and the opening / closing rope 39, which prevents the clamshell bucket 9 from moving toward the upper rotating body 3, and allows the clamshell bucket 9 to move smoothly.

[0041] The intermediate guide sheave shaft 35 is provided on a step surface 11G located on the front end 11E side of the arm body 11. A frame member 36 bent into a U-shaped cross section is fixed to the step surface 11G of the arm body 11. The intermediate guide sheave shaft 35 has a base end attached to the step surface 11G and a tip end attached to the frame member 36, so that the intermediate guide sheave shaft 35 extends upward from the step surface 11G while inclining slightly rearward.

[0042] The intermediate guide sheave 37 is rotatably provided on the step surface 11G of the arm body 11 via an intermediate guide sheave shaft 35. The intermediate guide sheave 37 is interposed between the opening / closing guide sheave 34 provided on the left side plate 11A of the arm body 11 and the slack adjustment sheave 45 provided on the right side plate 11B of the arm body 11, and the opening / closing rope 39 extending from the slack adjustment sheave 45 is wound around the intermediate guide sheave 37 to guide the opening / closing rope 39 to the opening / closing guide sheave 34.

[0043] In this way, even when the slack adjustment sheave 45 and the opening / closing guide sheave 34 are arranged on opposite sides of the arm body 11, the opening / closing rope 39 can be smoothly guided from the slack adjustment sheave 45 to the opening / closing guide sheave 34 via the intermediate guide sheave 37. The intermediate guide sheave 37 is arranged on the step surface 11G, which has a low distance from the lower plate 11D of the upper plate 11C of the arm body 11. This prevents the intermediate guide sheave 37 from protruding from the upper plate 11C of the arm body 11, and when the deep foundation excavator 1 excavates a shaft with the arm 10 held horizontally to the ground (as shown in FIG. 1), the height of the deep foundation excavator 1 above the ground can be kept as low as possible.

[0044] The lifting rope 38 is provided between the arm 10 and the clamshell bucket 9, and supports the clamshell bucket 9 so that it can be raised and lowered. The lifting rope 38 is made of a wire rope, and one end 38A of the lifting rope 38 is attached to the left side plate 11A of the arm body 11 via a slack detection device 47 (described later) and the like. The other end 38B of the lifting rope 38 is attached to the bucket support part 9A of the clamshell bucket 9 (see FIG. 1). The middle part of the lifting rope 38 is wound alternately around a plurality of first lifting sheaves 19 and a plurality of second lifting sheaves 23.

[0045] The opening / closing rope 39 is provided between the arm 10 and the clamshell bucket 9, and opens and closes a pair of buckets 9B of the clamshell bucket 9. The opening / closing rope 39 is made of a wire rope, and one end 39A of the opening / closing rope 39 is attached to the right side plate 11B of the arm body 11 via a slack detection device 62 (described later) or the like. The other end 39B of the opening / closing rope 39 is attached to the bucket support part 9A of the clamshell bucket 9 (see FIG. 1). The middle part of the opening / closing rope 39 is alternately wound around the multiple first opening / closing sheaves 21 and the multiple second opening / closing sheaves 30. The other end 39B side of the opening / closing rope 39 is alternately wound around the multiple upper sheaves 9E and the multiple lower sheaves 9F that constitute the clamshell bucket 9.

[0046] The clamshell bucket 9 descends when the lift cylinder 18 contracts and the first lift sheave 19 approaches the second lift sheave 23, and ascends when the lift cylinder 18 expands and the first lift sheave 19 moves away from the second lift sheave 23. Therefore, the descending distance (depth of the shaft) of the clamshell bucket 9 can be freely set by increasing the number of first lift sheaves 19 and second lift sheaves 23 or by changing the stroke of the lift cylinder 18. On the other hand, the clamshell bucket 9 opens when the opening / closing cylinder 31 contracts and the second opening / closing sheave 30 approaches the first opening / closing sheave 21, and closes when the opening / closing cylinder 31 expands and the second opening / closing sheave 30 moves away from the first opening / closing sheave 21.

[0047] The slack adjustment sheave moving mechanism 40 is provided on the right side plate 11B (second opposing surface) located on the front end 11E side of the arm body 11. The slack adjustment sheave moving mechanism 40 supports the slack adjustment sheave 45 so that it can move in the front-rear direction. As shown in Figures 3 and 12, the slack adjustment sheave moving mechanism 40 is configured to include a guide rail 41, a pair of slide members 42, a frame member 43, and a slack adjustment sheave shaft 44.

[0048] The guide rail 41 is made of a block body with a T-shaped cross section extending in the front-rear direction, and is fixed to the right side plate 11B of the arm body 11. A pair of slide members 42 are paired in the up-down direction with the guide rail 41 in between, and each slide member is slidably engaged with the guide rail 41. The frame member 43 is attached to the pair of slide members 42 using bolts or the like. A rod attachment pin 43A extending in the left-right direction is attached to the frame member 43, and a rod 46B of a slack adjustment cylinder 46 described later is attached to the rod attachment pin 43A. In addition, a slack adjustment sheave shaft 44 extending in the left-right direction adjacent to the rod attachment pin 43A is attached to the frame member 43.

[0049] The slack adjustment sheave 45 is rotatably attached to the slack adjustment sheave shaft 44 of the slack adjustment sheave moving mechanism 40. That is, the slack adjustment sheave 45 is provided on the right side plate 11B (second opposing surface) of the arm body 11 so as to be movable in the front-rear direction via the slack adjustment sheave moving mechanism 40. The slack adjustment sheave 45 is composed of a single sheave, and is supported rotatably around the slack adjustment sheave shaft 44 relative to the arm body 11.

[0050] The opening / closing rope 39 wound around the first opening / closing sheaves 21 and the second opening / closing sheaves 30 is wound around the slack adjustment sheave 45, the intermediate guide sheave 37, and the opening / closing guide sheave 34 in this order. The other end 39B of the opening / closing rope 39 wound around the opening / closing guide sheave 34 is then wound around the upper sheave 9E and the lower sheave 9F of the clamshell bucket 9, and the other end 39B of the opening / closing rope 39 is then attached to the bucket support portion 9A. In this manner, the slack adjustment sheave 45 around which the opening / closing rope 39 is wound, the second opening / closing sheaves 30, and the first opening / closing sheaves 21 are arranged in this order from the front end 11E of the arm body 11.

[0051] The slack adjustment cylinder 46 is provided on the right side plate 11B of the arm body 11, located in front of the opening / closing sheave moving mechanism 25. The slack adjustment cylinder 46 extends in the front-rear direction, and moves the slack adjustment sheave 45 closer to or farther from the second opening / closing sheave 30. The slack adjustment cylinder 46 has a tube 46A, a piston (not shown) inserted into the tube 46A, and a rod 46B whose base end is attached to the piston and whose tip protrudes from the tube 46A. The bottom side of the tube 46A is attached to the right side plate 11B of the arm body 11 via a bracket 46C. The tip of the rod 46B is attached to the frame member 43 of the slack adjustment sheave moving mechanism 40 via a pin or the like.

[0052] Therefore, the slack adjustment sheave 45 attached to the slack adjustment sheave moving mechanism 40 moves in the front-rear direction in response to the extension and retraction of the slack adjustment cylinder 46, and approaches and moves away from the second opening / closing sheave 30. As a result, for example, during excavation work of a vertical shaft using the deep foundation excavator 1, when the clamshell bucket 9 lands on the ground and the opening / closing rope 39 is in a slack state, the slack adjustment cylinder 46 is extended to move the slack adjustment sheave 45 away from the second opening / closing sheave 30, thereby taking up (removing) the slack in the opening / closing rope 39.

[0053] Next, the slack detection devices 47 and 62 used in this embodiment will be described. The lift rope slack detection device 47, which uses the lift rope 38 as the detected rope, is provided between one end 38A of the lift rope 38 and the left side plate 11A of the arm body 11, and detects slack in the lift rope 38. The opening / closing rope slack detection device 62, which uses the opening / closing rope 39 as the detected rope, is provided between one end 39A of the opening / closing rope 39 and the right side plate 11B of the arm body 11, and detects slack in the opening / closing rope 39. Here, since the lift rope slack detection device 47 and the opening / closing rope slack detection device 62 have the same configuration, hereinafter, only the slack detection device 47 will be described, and the description of the slack detection device 62 will be omitted.

[0054] As shown in Fig. 2, the slack detection device 47 is disposed inside (between the upper and lower lift ropes 38) the annular lift rope path 38C formed by the lift rope 38 wound around the first lift sheave 19 and the second lift sheave 23. The slack detection device 47 is provided between one end 38A of the lift rope 38 and the left side plate 11A of the arm body 11, and detects slack in the lift rope 38. As shown in Figs. 6 to 10, the slack detection device 47 includes an arm-side swinging member 48, a rope-side movable member 53, a coil spring 57, and a limit switch 59.

[0055] The arm side swing member 48 is swingably supported via a support pin 50 by a bracket 49 located rearward of the second lift sheave 23 and protruding from the left side plate 11A of the arm body 11. The bracket 49 has two base plates 49A that protrude leftward from the left side plate 11A of the arm body 11 while facing each other in the vertical direction at a fixed interval, and a pair of pin mounting plates 49B that are fixed between the two base plates 49A and face each other in the horizontal direction at a fixed interval. The pair of pin mounting plates 49B protrude rearward from the base plates 49A, and a support pin 50 extending perpendicular to the longitudinal direction of the arm 10 (arm body 11) is attached between the protruding ends.

[0056] As shown in FIG. 6 and FIG. 10, the arm side swinging member 48 has a cylindrical body 51 in the shape of a square tube having a rectangular cross section. The cylindrical body 51 is surrounded by a left pin mounting plate 51A and a right pin mounting plate 51B facing each other in the left-right direction, and an upper plate 51C and a lower plate 51D facing each other in the up-down direction, and the rope side movable member 53, the coil spring 57, etc. are accommodated inside. One end of the cylindrical body 51 is an opening 51E for inserting the rope side movable member 53, the coil spring 57, etc., inside, and the other end of the cylindrical body 51 is closed by a rectangular lid portion 51F. A support pin 50 is attached to the left pin mounting plate 51A and the right pin mounting plate 51B constituting the cylindrical body 51 on the front side of the opening 51E, straddling the opening 51E. Therefore, the arm side swinging member 48 is able to swing in the up-down direction around the support pin 50.

[0057] Here, the tip side of the left pin attachment plate 51A constituting the cylindrical body 51 is a stopper 51G extending forward from the support pin 50. The stopper 51G is disposed between the tips of the two substrates 49A of the bracket 49, and comes into contact with the substrate 49A when the arm side swinging member 48 swings excessively about the support pin 50. This limits the swing range of the arm side swinging member 48 about the support pin 50 by the stopper 51G. Also, a trapezoidally recessed notch 51H is formed on the edge of the lower plate 51D constituting the cylindrical body 51 on the opening 51E side (see FIG. 8).

[0058] A stepped cylindrical guide member 52 is fixed to the center of a cover portion 51F that closes the other end of the cylindrical body 51. The guide member 52 has a large diameter portion 52A disposed inside the cylindrical body 51 and a small diameter portion 52B that protrudes rearward from the cylindrical body 51, and the inner peripheral side of the guide member 52 forms a shaft insertion hole 52C that penetrates in the axial direction.

[0059] The rope-side movable member 53 is movably provided on the guide member 52 constituting the arm-side swing member 48, and one end 38A of the lift rope 38 is attached to the rope-side movable member 53. The rope-side movable member 53 has a stepped cylindrical shaft 54 ​​and a rope connection member 55 detachably attached to the cylindrical shaft 54. The cylindrical shaft 54 ​​has a small-diameter shaft portion 54A inserted axially movably into the shaft insertion hole 52C of the guide member 52, and a large-diameter shaft portion 54B housed in the cylindrical body 51. A female thread 54C is formed on the inner peripheral surface of the small-diameter shaft portion 54A, and a disk-shaped flange portion 54D having a larger diameter than the large-diameter shaft portion 54B is provided on the tip side of the large-diameter shaft portion 54B.

[0060] The rope connecting member 55 has a long threaded shaft 55A with a male thread formed on the outer circumferential surface, and a connecting plate 55B formed integrally with one end of the threaded shaft 55A. The threaded shaft 55A of the rope connecting member 55 is screwed into the female thread 54C of the cylindrical shaft 54 ​​(small diameter shaft portion 54A) and is positioned by a nut 55C. A terminal device 56 attached to one end 38A of the lifting rope 38 is pin-connected to the connecting plate 55B of the rope connecting member 55 so as to be rotatable in the vertical direction. As a result, the one end 38A of the lifting rope 38 is connected to the rope side movable member 53 via the terminal device 56.

[0061] Here, one end 38A of the lift rope 38 extends obliquely upward and forward from the lower end of the first lifting sheave 19, and is connected to the slack detection device 47 (rope connection member 55) via a terminal device 56. Therefore, as shown in Fig. 2, the angle θ formed between the lift rope 38 extending from the lower end of the first lifting sheave 19 to the lower end of the second lifting sheave 23 and the lift rope 38 extending from the lower end of the first lifting sheave 19 to the slack detection device 47 changes according to the movement of the first lifting sheave 19 due to the extension and contraction of the lift cylinder 18. In contrast, the slack detection device 47 has an arm-side swinging member 48 supported on a bracket 49 protruding from the left side plate 11A of the arm body 11 so as to be swingable about a support pin 50 perpendicular to the longitudinal direction of the arm body 11, and a rope-side movable member 53 connected to one end 38A of the lifting rope 38 is movably attached to the arm-side swinging member 48. Therefore, even if the angle θ changes in response to the extension and retraction of the lifting cylinder 18, the arm-side swinging member 48 swings about the support pin 50, so that the one end 38A of the lifting rope 38 smoothly follows the change in the angle θ without being subjected to an excessive bending force.

[0062] The coil spring 57 as an elastic member is provided between the guide member 52 of the arm side swinging member 48 and the cylindrical shaft 54 ​​of the rope side movable member 53. The coil spring 57 is arranged on the outer periphery of the large diameter shaft portion 54B of the cylindrical shaft 54 ​​constituting the rope side movable member 53, and is provided expandably between the flange portion 54D of the cylindrical shaft 54 ​​and the large diameter portion 52A of the guide member 52. The coil spring 57 is formed of a compression spring, and urges the rope side movable member 53 (the flange portion 54D of the cylindrical shaft 54) toward the support pin 50 against the tension acting on the lift rope 38. Therefore, the flange portion 54D of the cylindrical shaft 54 ​​is displaced in the axial direction inside the tube 51 according to the change in the tension acting on the lift rope 38, and when the lift rope 38 is loosened and the tension falls below a predetermined value, it is pressed by the coil spring 57 to approach the support pin 50.

[0063] The buffer material 58 is provided between the flange portion 54D of the cylindrical shaft 54 ​​constituting the rope-side movable member 53 and the support pin 50. The buffer material 58 is formed in a cylindrical shape using an elastic material such as rubber, and is supported by the support pin 50 inserted into the inner periphery. The buffer material 58 prevents the flange portion 54D of the cylindrical shaft 54, which is biased by the coil spring 57, from directly colliding with the support pin 50, protecting the support pin 50 and suppressing noise. Here, the distance between the flange portion 54D of the cylindrical shaft 54 ​​and the buffer material 58 is set to a small dimension (for example, 10 mm or less). This allows the length dimension of the slack detection device 47 to be reduced.

[0064] Moreover, the support pin 50 with the cushioning material 58 attached is attached to the tip side of the left pin mounting plate 51A and the right pin mounting plate 51B of the cylinder 51 which houses the cylindrical shaft 54 ​​and the coil spring 57 inside, and is disposed across the opening 51E of the cylinder 51. As a result, even if the lift rope 38 is cut with the coil spring 57 in a compressed state, the cylindrical shaft 54, the coil spring 57, etc. collide with the support pin 50 and are prevented from flying out of the cylinder 51.

[0065] The limit switch 59 as a sensor is provided on the lower plate 51D of the cylinder 51 constituting the arm side swinging member 48. As shown in Figs. 7 and 9, the limit switch 59 has an actuator 59A rotatably attached to the switch body. The limit switch 59 is attached to a spacer 60 protruding downward from the lower plate 51D of the cylinder 51 via a bracket 61 or the like, and is arranged outside the cylinder 51. The actuator 59A protrudes into the cylinder 51 through a notch 51H formed in the lower plate 51D, and is arranged between the flange 54D of the cylindrical shaft 54 ​​and the support pin 50. Since the limit switch 59 is provided on the cylinder 51 of the arm side swinging member 48, even if the lift rope 38 becomes loose, the limit switch 59 can be prevented from coming into contact with the loose lift rope 38, and the limit switch 59 can be protected.

[0066] The actuator 59A of the limit switch 59 is operated by the flange portion 54D of the cylindrical shaft 54 ​​pressed by the coil spring 57 when the lift rope 38 becomes loose and the tension falls below a predetermined value. In this way, the limit switch 59 detects that the lift rope 38 has become loose and the tension falls below a predetermined value and outputs a detection signal. In this way, the limit switch 59 detects whether the tension acting on the lift rope 38 has become below a predetermined value based on the movement of the rope-side movable member 53 (cylindrical shaft 54). When the controller (not shown) that controls the operation of the bucket lifting / opening device 17 determines that the tension of the lift rope 38 has become below a predetermined value and that the lift rope 38 has become loose based on the detection signal from the limit switch 59, it stops the payout operation of the lift rope 38 by the lift cylinder 18, for example.

[0067] The opening / closing rope slack detector 62, which uses the opening / closing rope 39 as the detected rope, is provided between one end 39A of the opening / closing rope 39 and the right side plate 11B of the arm body 11. As shown in Fig. 4, the slack detector 62 is disposed inside (between the upper opening / closing rope 39 and the lower opening / closing rope 39) the circular opening / closing rope path 39C formed by the opening / closing rope 39 wound around the first opening / closing sheave 21 and the second opening / closing sheave 30.

[0068] The slack detection device 62 is configured similarly to the above-mentioned lift rope slack detection device 47, and detects whether or not the tension acting on the opening / closing rope 39 has fallen below a predetermined value. When the opening / closing rope 39 slackens and the tension falls below the predetermined value, a controller (not shown) that controls the operation of the bucket lifting / opening device 17 removes the slack in the opening / closing rope 39, for example, by extending the slack adjustment cylinder 46.

[0069] The deep foundation excavator 1 according to this embodiment has the configuration as described above, and the operation of excavating a vertical shaft using the deep foundation excavator 1 will be described below.

[0070] The operator in the cab 4 drives the deep foundation excavator 1 to the work site by himself, and then operates the boom cylinder 7 to lift the tip of the boom 6 upward as shown in FIG. 1, and for example operates the arm cylinder 8 to hold the arm 10 in a horizontal position relative to the ground. The position of the arm 10 relative to the ground (the inclination of the arm 10) can be appropriately changed according to the limit of the working height. Next, with the clamshell bucket 9 closed, the shaft is placed above the ground to be excavated, and the lifting cylinder 18 is contracted. As a result, the sheave mounting member 14 moves forward along the guide arms 12 and 13, and the first lifting sheave 19 approaches the second lifting sheave 23, and the first opening / closing sheave 21 approaches the second opening / closing sheave 30. As a result, the lifting rope 38 and the opening / closing rope 39 are unwound from the arm 10, and the clamshell bucket 9 descends.

[0071] When the clamshell bucket 9 reaches a position several meters (for example, 2 to 3 meters) above the ground, the operator stops the lowering operation of the clamshell bucket 9 by the lifting cylinder 18, and then retracts the opening / closing cylinder 31. This causes the second opening / closing sheave 30 attached to the opening / closing sheave moving mechanism 25 to approach the first opening / closing sheave 21. As a result, the opening / closing rope 39 is reeled out from the arm 10, and the pair of buckets 9B of the clamshell bucket 9 are fully opened. After the clamshell bucket 9 is fully opened, the operator retracts the lifting cylinder 18 again. This causes the fully open clamshell bucket 9 to descend, and the lower ends of the pair of buckets 9B land on the ground.

[0072] After the lower end of the clamshell bucket 9 lands on the ground, the operator continues the operation of retracting the lifting cylinder 18, and causes the clamshell bucket 9 to sink into the ground by its own weight. Next, before closing the clamshell bucket 9, the operator extends the slack adjustment cylinder 46, and moves the slack adjustment sheave 45 attached to the slack adjustment sheave moving mechanism 40 away from the second opening / closing sheave 30. As a result, the lifting rope 38 remains slack, and only the slack in the opening / closing rope 39 is removed.

[0073] Next, the operator extends the opening / closing cylinder 31, and separates the second opening / closing sheave 30 attached to the opening / closing sheave moving mechanism 25 from the first opening / closing sheave 21, thereby pulling up the opening / closing rope 39 toward the arm 10. As a result, the clamshell bucket 9 closes while sinking into the ground under its own weight, and can scoop up a large amount of earth and sand. In this case, by extending the slack adjustment cylinder 46 at a stage before closing the clamshell bucket 9, only the slack in the opening / closing rope 39 is removed while the lift rope 38 remains slack. As a result, the clamshell bucket 9 can be closed at the same time as the opening / closing cylinder 31 is extended, and earth and sand can be excavated quickly.

[0074] After closing the clamshell bucket 9 to scoop up the soil, the operator extends the lift cylinder 18. At this time, if the lift rope 38 is loose after scooping up the soil, the lift cylinder 18 is extended and the slack adjustment cylinder 46 is contracted at the same time. As a result, the first lift sheave 19 attached to the sheave mounting member 14 separates from the second lift sheave 23, the lift rope 38 is pulled up toward the arm 10, and the first opening / closing sheave 21 separates from the second opening / closing sheave 30, and the opening / closing rope 39 is pulled up toward the arm 10. As a result, the lift rope 38 and the opening / closing rope 39 are pulled up together toward the arm 10, and the clamshell bucket 9 is lifted up by the lift rope 38 and the opening / closing rope 39 while holding the soil.

[0075] After the clamshell bucket 9 has been raised to the outside of the shaft, the upper rotating body 3 is rotated, for example, to move the clamshell bucket 9 above the bed of a dump truck (not shown). In this state, the operator contracts the opening / closing cylinder 31 and moves the second opening / closing sheave 30 attached to the opening / closing sheave moving mechanism 25 closer to the first opening / closing sheave 21. As a result, the opening / closing rope 39 is pulled out from the arm 10, and the clamshell bucket 9 opens, allowing the excavated soil and sand to be discharged onto the bed of the dump truck.

[0076] In this way, after the soil has been dumped onto the bed of the dump truck, the upper rotating body 3 is rotated to move the clamshell bucket 9 above the shaft, and the shaft can be excavated by repeating the above-mentioned work (operations).

[0077] As described above, when the deep foundation excavator 1 is excavating a shaft, the lifting cylinder 18 is contracted and the lifting rope 38 is let out, allowing the clamshell bucket 9 to sink into the ground by its own weight and excavate a large amount of earth and sand. However, if the lifting rope 38 becomes loose enough to allow the clamshell bucket 9 to sink into the ground, time is wasted until the clamshell bucket 9 holding the earth and sand rises when the lifting cylinder 18 is extended, and the workability of the excavation work is reduced.

[0078] The slack detection device 47 according to this embodiment detects a slack state of the lift rope 38 based on whether or not the tension acting on the lift rope 38 has fallen below a predetermined value. The operation of the slack detection device 47 will now be described.

[0079] When the clamshell bucket 9 is suspended by the lift ropes 38, the lift ropes 38 are not loosened and tension exceeding a predetermined value acts on the lift ropes 38. In this state, the flange portion 54D of the cylindrical shaft 54 ​​moves toward the lid portion 51F of the cylinder 51 against the coil spring 57 and maintains a state separated from the limit switch 59. Therefore, the actuator 59A of the limit switch 59 is not operated by the flange portion 54D of the cylindrical shaft 54.

[0080] When the lift cylinder 18 is retracted and the clamshell bucket 9 is lowered into the ground, the lift rope 38 may become significantly slack. In this case, the tension acting on the lift rope 38 falls below a predetermined value, and the flange portion 54D of the cylindrical shaft 54 ​​is pressed by the coil spring 57 and moves toward the support pin 50. As a result, the actuator 59A of the limit switch 59 is operated by the flange portion 54D, and the limit switch 59 outputs a detection signal to a controller (not shown) that controls the operation of the bucket lifting / opening device 17. The controller determines that a predetermined slack has occurred in the lift rope 38 based on the detection signal from the limit switch 59, and stops the retraction operation of the lift cylinder 18 (the payout operation of the lift rope 38).

[0081] In this way, the slack detection device 47 detects that the tension acting on the lift rope 38 during the excavation work of a shaft falls below a predetermined value, thereby preventing excessive slack in the lift rope 38. As a result, after the clamshell bucket 9 is closed and the soil is excavated, the lift rope 38 can be wound up and the clamshell bucket 9 can be quickly lifted by extending the lift cylinder 18, thereby improving the workability of the excavation work.

[0082] Meanwhile, the slack detection device 62 provided between one end 39A of the opening / closing rope 39 and the right side plate 11B of the arm body 11 detects slack in the opening / closing rope 39 depending on whether or not the tension acting on the opening / closing rope 39 has become equal to or less than a predetermined value. For example, when the clamshell bucket 9 lands on the ground, if a predetermined slack occurs in the opening / closing rope 39, a detection signal is output from the slack detection device 62 to the controller. The controller determines that a predetermined slack has occurred in the opening / closing rope 39 based on the detection signal from the slack detection device 62, and causes the slack adjustment cylinder 46 to perform an extension operation. As a result, the slack in the opening / closing rope 39 is quickly removed, so that the clamshell bucket 9 can be closed by the opening / closing cylinder 31 to excavate soil and sand, thereby improving the workability of the excavation work.

[0083] Here, the slack detection device 47 has a shape larger than the rope diameter of the lift rope 38. On the other hand, since the lift rope 38 is alternately wound around a plurality of first lift sheaves 19 and second lift sheaves 23, the interval between adjacent lift ropes 38 is narrow. For this reason, if the slack adjustment device is arranged adjacent to the lift rope 38, there is a risk that the lift rope 38 will come into contact with the slack detection device and be damaged. In contrast, the slack detection device 47 according to this embodiment is arranged inside the annular lift rope path 38C formed by the lift rope 38 wound around the first lift sheave 19 and the second lift sheave 23. Since the sheave diameters of the first lift sheave 19 and the second lift sheave 23 are larger than the slack detection device 47, a sufficient space can be secured around the slack detection device 47. As a result, it is possible to reliably prevent the lift ropes 38 from interfering with the slack detector 47, and it is possible to protect the lift ropes 38, etc. This also applies to the slack detector 62 for the opening and closing ropes.

[0084] The slack detection device 47 is configured to include an arm side swinging member 48 supported on a bracket 49 protruding from the left side panel 11A of the arm body 11 so as to be swingable about a support pin 50 perpendicular to the longitudinal direction of the arm body 11, and a rope side movable member 53 movably mounted relative to the arm side swinging member 48, and one end 38A of the lifting rope 38 is attached to the rope side movable member 53 (rope connection member 55).

[0085] As a result, even if the angle θ between the lift rope 38 extending from the lower end of the first lift sheave 19 to the lower end of the second lift sheave 23 and the lift rope 38 extending from the lower end of the first lift sheave 19 to the slack detection device 47 changes in response to the extension and contraction of the lift cylinder 18, the arm side swing member 48 swings around the support pin 50, thereby preventing excessive bending force from acting on one end 38A of the lift rope 38. Moreover, compared to a rope tension detection device that rotates around a spherical contact surface as a fulcrum as in Patent Document 2, for example, the slack detection device 47 can limit the movement of the arm side swing member 48 to only swinging in the vertical direction around the support pin 50. As a result, it is possible to prevent the arm side swing member 48 from colliding with the arm body 11, and to protect the arm body 11, the slack detection device 47, etc.

[0086] A stopper 51G extending forward from the support pin 50 is provided on the tip side of the left pin mounting plate 51A constituting the cylinder body 51 of the arm side swinging member 48. The stopper 51G abuts against the base plate 49A when the arm side swinging member 48 swings excessively around the support pin 50, thereby limiting the swing range of the arm side swinging member 48 around the support pin 50. This makes it possible to prevent the arm side swinging member 48 from swinging excessively around the support pin 50 when the lift rope 38 becomes loose, and to prevent one end 38A of the lift rope 38 from bending downward significantly. As a result, the lift ropes 38 can be protected by preventing them from coming into contact with each other and being damaged.

[0087] Furthermore, the support pin 50, which supports the arm-side swinging member 48 so that it can swing, is attached between a left pin mounting plate 51A and a right pin mounting plate 51B of the cylinder 51 that constitutes the arm-side swinging member 48, and is disposed straddling an opening 51E for inserting the cylindrical shaft 54, the coil spring 57, etc. into the cylinder 51. As a result, even if the lift rope 38 is cut when the coil spring 57 housed in the cylinder 51 is in a contracted state, the cylindrical shaft 54, the coil spring 57, etc. collide with the support pin 50, and therefore the support pin 50 can prevent these from jumping out of the cylinder 51.

[0088] In addition, a buffer material 58 is provided between the flange portion 54D of the cylindrical shaft 54 ​​constituting the rope side movable member 53 and the support pin 50. As a result, even if the lift rope 38 becomes loose, the buffer material 58 can prevent the flange portion 54D of the cylindrical shaft 54, which is biased by the coil spring 57, from directly colliding with the support pin 50. As a result, the support pin 50 is protected and noise caused by the collision between the flange portion 54D and the support pin 50 can be suppressed.

[0089] In this case, the distance between the flange portion 54D of the cylindrical shaft 54 ​​and the buffer material 58 is set to the smallest possible dimension, so that the length dimension of the entire loosening detection device 47 can be shortened. As a result, the first lifting sheave 19 can be brought closer to the second lifting sheave 23 by the amount of the shortened loosening detection device 47, and the rear end positions of the guide arms 12, 13 provided on the arm body 11 can be arranged on the front side. As a result, the protruding length of the guide arms 12, 13 from the rear end of the upper rotating body 3 can be reduced, and the risk that the guide arms 12, 13 will interfere with surrounding obstacles when the upper rotating body 3 rotates can be reduced. In addition, the coil spring 57, the buffer material 58, and the actuator 59A are arranged inside the cylindrical body 51, and the stopper 51G is arranged inside the bracket 49, so that the loosening detection device 47 is further made compact in the length direction.

[0090] In addition, the limit switch 59 that detects slack in the lift rope 38 is attached to the lower plate 51D of the cylinder 51 constituting the arm-side swinging member 48, and is disposed outside the cylinder 51. This makes it possible to prevent the limit switch 59 from coming into contact with the loosened lift rope 38 even if the lift rope 38 becomes loose, and the limit switch 59 can be protected. Moreover, the actuator 59A of the limit switch 59 is disposed inside the cylinder 51 through a notch 51H formed in the lower plate 51D. This allows the limit switch 59 to be attached to the cylinder 51 while ensuring the strength of the cylinder 51, and the actuator 59A is operated by the flange 54D of the cylindrical shaft 54 ​​inside the cylinder 51, thereby enabling the slack in the lift rope 38 to be accurately detected.

[0091] Thus, in the embodiment, the bucket lifting / opening device 17 is provided on the arm 10, and includes a first lifting sheave 19 and a first opening / closing sheave 21 which are moved in the length direction of the arm 10 by a lifting cylinder 18, a second lifting sheave 23 and a second opening / closing sheave 30 which are provided on the arm 10 spaced apart from the first lifting sheave 19 and the first opening / closing sheave 21, respectively, a lifting rope 38 which is wound around the first lifting sheave 19 and the second lifting sheave 23, and has one end 38A attached to the arm 10 and the other end 38B attached to the clamshell bucket 9, and a lifting rope 38 which is wound around the first opening / closing sheave 21 and the second opening / closing sheave 30, and has one end 39A In a deep foundation excavator 1 comprising an opening / closing rope 39 attached to an arm and having its other end 39B attached to a clamshell bucket 9, and a slack detection device 47 (62) provided at one end of the detection rope to be detected, which is one of the lifting rope 38 and the opening / closing rope 39, for detecting slack in the detection rope, the slack detection device 47 (62) is positioned inside the annular lifting rope path 38C formed by the lifting rope 38 wound around the first lifting sheave 19 and the second lifting sheave 23, and / or inside the annular opening / closing rope path 39C formed by the opening / closing rope 39 wound around the first opening / closing sheave 21 and the second opening / closing sheave 30.

[0092] According to this configuration, when the rope to be detected is the lift rope 38, the slack detection device 47 can be disposed inside the lift rope path 38C formed by the lift rope 38. Therefore, even if the slack detection device 47 larger than the rope diameter is provided at one end 38A of the lift rope 38, interference between the slack detection device 47 and the lift rope 38 can be prevented. Also, when the rope to be detected is the opening / closing rope 39, the slack detection device 62 can be disposed inside the opening / closing rope path 39C formed by the opening / closing rope 39. Therefore, even if the slack detection device 62 larger than the rope diameter is provided at one end 39A of the opening / closing rope 39, interference between the slack detection device 62 and the opening / closing rope 39 can be prevented.

[0093] In an embodiment, the slack detection device 47 includes an arm side swinging member 48 that is swingably attached to the arm 10 around a support pin 50 extending in a direction perpendicular to the longitudinal direction of the arm 10, a rope side movable member 53 that is movably attached to the arm side swinging member 48 and has one end 38A of the lifting rope 38 attached to it, a coil spring 57 that is extendable and contractible between the arm side swinging member 48 and the rope side movable member 53 and biases the rope side movable member 53 toward the support pin 50 against the tension acting on the lifting rope 38, and a limit switch 59 that is attached to the arm side swinging member 48 and detects whether the tension acting on the lifting rope 38 has fallen below a predetermined value based on the movement of the rope side movable member 53.

[0094] According to this configuration, when the lift rope 38 becomes loose and the tension falls below a predetermined value, the coil spring 57 moves the rope-side movable member 53 toward the support pin 50. Therefore, the movement of the rope-side movable member 53 can be detected by the limit switch 59 to detect the looseness of the lift rope 38. Here, the angle θ between the lift rope 38 extending from the lower end of the first lift sheave 19 to the lower end of the second lift sheave 23 and the lift rope 38 extending from the lower end of the first lift sheave 19 to the looseness detector 47 changes according to the extension and contraction of the lift cylinder 18. However, by the arm-side swing member 48 swinging about the support pin 50, it is possible to prevent excessive bending force from acting on the one end 38A of the lift rope 38, and to extend the life of the lift rope 38. Furthermore, since the movement of the arm side swinging member 48 is limited to only swinging in the vertical direction around the support pin 50, it is possible to prevent the arm side swinging member 48 from colliding with the arm main body 11, thereby protecting the arm main body 11, the loosening detection device 47, etc.

[0095] In this embodiment, the arm side swinging member 48 is swingably supported via a support pin 50 on a bracket 49 protruding from the outer surface of the arm body 11, and the arm side swinging member 48 is provided with a stopper 51G that abuts against the bracket 49 to limit the swing range around the support pin 50. With this configuration, when the lift rope 38 becomes loose, the arm side swinging member 48 swings excessively around the support pin 50, preventing one end 38A of the lift rope 38 from bending downward significantly. As a result, the lift ropes 38 can be protected by preventing the lift ropes 38 from coming into contact with each other and being damaged.

[0096] In the embodiment, a buffer material 58 is provided between the support pin 50 and the rope-side movable member 53. With this configuration, even if the hoisting rope 38 becomes loose, the buffer material 58 can prevent the rope-side movable member 53, which is biased by the coil spring 57, from directly colliding with the support pin 50. As a result, the support pin 50 is protected, and noise caused by the collision between the rope-side movable member 53 and the support pin 50 can be suppressed.

[0097] In the embodiment, the arm side swinging member 48 has a cylinder 51 that houses the rope side movable member 53 and the coil spring 57 therein, an opening 51E for inserting the rope side movable member 53 and the coil spring 57 into the cylinder 51, and a left pin mounting plate 51A and a right pin mounting plate 51B that face each other across the opening 51E, and the support pin 50 is attached to the left pin mounting plate 51A and the right pin mounting plate 51B across the opening 51E. According to this configuration, even if the lift rope 38 is cut while the coil spring 57 housed in the cylinder 51 is in a contracted state, the arm side swinging member 48, the coil spring 57, etc. collide with the support pin 50, so that the support pin 50 can prevent them from jumping out of the cylinder 51.

[0098] In the embodiment, the limit switch 59 has an actuator 59A operated by the rope-side movable member 53, the limit switch 59 is provided outside the cylinder 51 constituting the arm-side swinging member 48, and the actuator 59A is disposed inside the cylinder 51 through a notch 51H formed in the cylinder 51. With this configuration, even if the lift rope 38 becomes loose, the limit switch 59 can be prevented from coming into contact with the loosened lift rope 38, and the limit switch 59 can be protected.

[0099] In the embodiment, the slack detector 47 is provided at one end 38A of the lift rope 38, and the slack detector 62 is provided at one end 39A of the opening / closing rope 39. However, the present invention is not limited to this, and the slack detector may be provided at either the lift rope or the opening / closing rope. For example, as shown in a modified example in FIG. 11, the one end 39A of the opening / closing rope 39 may be attached to a bracket 63 protruding from the right side plate 11B of the arm body 11, and the slack detector may be provided at only one end of the lift rope. According to this configuration, the one end 39A of the opening / closing rope 39 can be disposed adjacent to the opening / closing rope 39 wound around the first opening / closing sheaves 21 and the second opening / closing sheaves 30. In this case, the slack of the opening / closing rope 39 can be indirectly detected based on the change in the cylinder pressure of the lift cylinder 18, for example.

[0100] In the embodiment, a contact-type limit switch 59 is used as a sensor for detecting whether the tension acting on the lift rope 38 is equal to or lower than a predetermined value. However, the present invention is not limited to this, and a non-contact switch such as a proximity switch or a load cell may be used. [Explanation of symbols]

[0101] 1 Deep foundation excavator 2 Undercarriage (car body) 3 Upper rotating body (car body) 9. Clamshell Bucket 10 Arm 17 Bucket lifting and opening device 18 Lifting cylinder 19 First lift sheave 21 First opening and closing sheave 23 Second lift sheave 30 Second opening and closing sheave 38 Ascending and Descending Rope 38A,39A one end 38B,39B other end 38C Ascending and descending rope route 39 Opening and closing rope 39C Opening and closing rope route 47,62 Loosening detection device 48 Arm side swinging member 49 Bracket 50 Support pin 51 Cylinder 51A Left pin mounting plate 51B Right pin mounting plate 51E opening 51G Stopper 51H Notch 53 Rope side movable member 57 Coil spring (elastic member) 59 Limit switch (sensor) 59A Actuator

Claims

1. The clamshell bucket lifting / opening device is provided on the arm and performs lifting / opening and closing operations of the clamshell bucket. The bucket lifting and opening / closing device is a first lifting sheave and a first opening / closing sheave that are provided on the arm and move in the length direction of the arm by a lifting cylinder; a second lifting sheave and a second opening / closing sheave that are provided on the arm at a distance from the first lifting sheave and the first opening / closing sheave, respectively; a lifting rope that is wound around the first lifting sheave and the second lifting sheave and has one end attached to the arm and the other end attached to the clamshell bucket; an opening / closing rope that is wound around the first opening / closing sheave and the second opening / closing sheave and has one end attached to the arm and the other end attached to the clamshell bucket; and a slack detection device that is provided on one end of a detection rope that is to be detected, one of the lifting rope and the opening / closing rope, and that detects slack in the detection rope, A deep foundation excavator characterized in that the slack detection device is arranged inside the circular lifting rope path formed by the lifting rope wound around the first lifting sheave and the second lifting sheave, and / or inside the circular opening and closing rope path formed by the opening and closing rope wound around the first opening and closing sheave and the second opening and closing sheave.

2. The loosening detection device is an arm-side swinging member attached to the arm so as to be swingable about a support pin extending in a direction perpendicular to the length of the arm; a rope-side movable member provided movably relative to the arm-side swinging member and having one end of the detection target rope attached thereto; an elastic member that is extendable and contractible between the arm-side swinging member and the rope-side movable member and that urges the rope-side movable member toward the support pin against the tension acting on the detection rope; The deep foundation excavator described in claim 1, characterized in that it is configured to include a sensor provided on the arm side swinging member that detects whether the tension acting on the detected rope has fallen below a predetermined value based on the movement of the rope side movable member.

3. A deep foundation excavator as described in Claim 2, characterized in that it further comprises a stopper that limits the swing range of the arm side swinging member centered on the support pin.

4. The deep foundation excavator according to claim 2, wherein a buffer material is provided between the support pin and the rope-side movable member.

5. The arm-side swinging member has a cylindrical body that accommodates the rope-side movable member and the elastic member therein, an opening for inserting the rope-side movable member and the elastic member into the cylindrical body, and a pair of pin mounting plates that face each other across the opening, The deep foundation excavator according to claim 2, wherein the support pin is attached to the pair of pin mounting plates across the opening.

6. The deep foundation excavator according to claim 5, wherein the sensor is provided outside the cylindrical body constituting the arm side swinging member.

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