Deep foundation drilling machine

Abstract

A base arm (11) is formed as a cylindrical body comprising a left side plate (11A) and a right side plate (11B) facing at an interval in a direction orthogonal to the length direction, and a second up / down sieve shaft (24) and a second opening / closing sieve shaft (29) are disposed between an upper guide arm coupling pin (13B) and a lower guide arm coupling pin (14B) in the up-down direction of the base arm (11). The base arm (11) is provided with a reinforcing plate (12) extending in the length direction of the base arm (11) in a state in which the left side plate (11A) and the right side plate (11B) are coupled, and a part of the reinforcing plate (12) is disposed between the upper guide arm coupling pin (13B) and the lower guide arm coupling pin (14B) in the up-down direction of the base arm (11).

Description

Technical Field

[0001] The present disclosure relates to a deep foundation excavator suitably used for shaft excavation work and the like.

Background Art

[0002] As a working machine suitably used for shaft excavation work and the like, a deep foundation excavator is known. The working device of the deep foundation excavator includes a boom attached to a vehicle body, an arm rotatably attached to the tip of the boom, a clam shell bucket provided so as to be able to move up and down with respect to the arm, and a bucket hoisting and opening / closing device that controls the hoisting and opening / closing operations of the clam shell bucket. The bucket hoisting and opening / closing device includes a movable sheave movable in the longitudinal direction of the arm, a fixed sheave fixed to the arm, a hoisting rope and an opening / closing rope wound around the movable sheave and the fixed sheave, a hoisting cylinder for hoisting the clam shell bucket, and an opening / closing cylinder for opening and closing the clam shell bucket.

[0003] The hoisting cylinder changes the distance between the movable sheave and the fixed sheave to unwind and wind up the hoisting rope, thereby hoisting and lowering the clam shell bucket. The opening / closing cylinder changes the distance between the movable sheave and the fixed sheave to unwind and wind up the opening / closing rope, thereby opening and closing the clam shell bucket. The deep foundation excavator lowers the clam shell bucket into the shaft with the tip of the arm arranged above the shaft, and excavates earth and sand by opening and closing the clam shell bucket (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] However, conventional deep foundation excavators have the main components of the bucket lifting and opening / closing device located on the rear side of the arm in order to improve stability when unwinding and winding the lifting rope and opening / closing rope by changing the distance between the movable sheave and the fixed sheave. As a result, stress concentration is likely to occur on the rear side of the arm in conventional deep foundation excavators, that is, in the area from the attachment point to the boom to the rear end of the arm. Consequently, conventional deep foundation excavators have the problem of easily losing arm strength, leading to a premature reduction in lifespan.

[0006] The object of the present invention is to provide a deep foundation drilling machine that can increase the strength of the base arm.

[0007] The present invention comprises a self-propelled vehicle body and a work device provided on the vehicle body, the work device comprising: a base arm rotatably mounted on the vehicle body and having a clamshell bucket positioned to be raised and lowered on one end in the longitudinal direction; an upper guide arm and a lower guide arm connected to the other end of the base arm at a constant distance in the vertical direction via an upper guide arm connecting pin and a lower guide arm connecting pin, extending in the longitudinal direction of the base arm; a first lifting sheave and a first opening / closing sheave provided to be movable along the upper guide arm and the lower guide arm; a lifting cylinder attached to the base arm for moving the first lifting sheave and the first opening / closing sheave; a second lifting sheave and a second opening / closing sheave spaced apart from the first lifting sheave and the first opening / closing sheave, and rotatably mounted on the base arm about the sheave axis, respectively; and A deep foundation excavator comprising a lifting rope wound around a first lifting sheave and a second lifting sheave to raise and lower the clamshell bucket, and an opening / closing rope wound around a first opening / closing sheave and a second opening / closing sheave to open and close the clamshell bucket, wherein the base arm is formed as a cylindrical body having a pair of side plates that are spaced apart and facing each other in a direction perpendicular to the longitudinal direction, the sheave shafts of the second lifting sheave and the second opening / closing sheave are arranged between the upper guide arm connecting pin and the lower guide arm connecting pin in the vertical direction of the base arm, the base arm is provided with a reinforcing plate fixed to at least one of the pair of side plates and extending in the longitudinal direction of the base arm, and a part of the reinforcing plate is arranged between the upper guide arm connecting pin and the lower guide arm connecting pin in the vertical direction of the base arm.

[0008] According to the present invention, by fixing a reinforcing plate to at least one of the pair of side plates of the base arm, deformation and stress concentration due to external forces on the pair of side plates can be suppressed, thereby increasing the strength of the base arm. [Brief explanation of the drawing]

[0009] [Figure 1]This is a left side view showing a deep foundation drilling machine according to an embodiment of the present invention. [Figure 2] This is a left side view showing the arm, bucket lifting / opening mechanism, etc. [Figure 3] This is a plan view showing the arm, bucket lifting / opening / closing mechanism, etc. [Figure 4] This is a partially broken right side view showing the arm, bucket lifting / opening mechanism, etc. [Figure 5] This is a diagram of the arm after it has been disassembled. [Figure 6] This is a cross-sectional view of the cylinder holding portion of the base arm, taken from the direction indicated by the arrow VI-VI in Figure 5. [Figure 7] This is a left side view showing a magnified view of the base arm, second lifting sheave, etc. [Figure 8] This is a cross-sectional view of the base arm, second lifting sheave, etc., taken from the direction indicated by arrow VIII-VIII in Figure 7. [Figure 9] This is a right side view showing a magnified view of the base arm, second opening / closing sheave, opening / closing cylinder, etc. [Figure 10] This is a plan view showing a magnified view of the base arm, opening / closing cylinder, lifting rope mounting bracket, and other components. [Figure 11] This is a bottom view of the base arm, boom mounting bracket, second lifting sheave, second opening / closing sheave, etc., as seen from the direction indicated by arrow XI-XI in Figure 2, with the ropes omitted. [Figure 12] This is a left side view showing a modified base arm. [Figure 13] This is a cross-sectional view of the base arm, second lifting sheave, etc., taken from the direction indicated by arrow XIII-XIII in Figure 12. [Modes for carrying out the invention]

[0010] Hereinafter, a deep foundation excavator according to an embodiment of the present invention will be described in detail with reference to the attached drawings. In this embodiment, the direction of travel of the deep foundation excavator will be described as the front-rear direction, and the direction perpendicular to the travel direction will be described as the left-right direction.

[0011] The deep foundation excavator 1 is manufactured, for example, based on a crawler-type hydraulic excavator. The deep foundation excavator 1 consists of a self-propelled crawler-type lower vehicle 2, an upper rotating vehicle 3 that is rotatably mounted on the lower vehicle 2, and a work device 5 provided on the upper rotating vehicle 3, which will be described later. The lower vehicle 2 and the upper rotating vehicle 3 constitute the body of the deep foundation excavator 1.

[0012] The cab 4 is located on the left front side of the upper slewing body 3. The cab 4 defines the driver's cabin, and inside the cab 4 is a driver's seat 4A where the operator sits. Around the driver's seat 4A are operating devices (not shown) for operating the movement of the lower traveling body 2, the rotation of the upper slewing body 3, and the work device 5.

[0013] The work device 5 comprises a boom 6 mounted on the upper slewing body 3 so as to be rotatable in the vertical direction, an arm 10 (described later), a clamshell bucket 9, and a bucket lifting / opening / closing device 16. A boom cylinder 7 is provided between the upper slewing body 3 and the boom 6, and the boom 6 rotates relative to the upper slewing body 3 in accordance with the extension and retraction movement 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 or the upper slewing body 3 in accordance with the extension and retraction movement of the arm cylinder 8.

[0014] The clamshell bucket 9 is positioned at the front end (one end in the longitudinal direction) of the base arm 11, which will be described later, and is suspended so as to be able to move up and down using a lifting rope 38, which will be described later. The clamshell bucket 9 has a bucket support section 9A, a pair of buckets 9B, a connecting bracket 9C, and a pair of opening / closing arms 9D. The pair of buckets 9B are provided below the bucket support section 9A so as to be able to open and close. The connecting bracket 9C is rotatably connected to the pair of buckets 9B. The pair of opening / closing arms 9D connect the bucket support section 9A and the pair of buckets 9B, respectively. The bucket support section 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 are vertically opposed to the upper sheaves 9E.

[0015] The other end 38B of the lifting rope 38 is attached to the bucket support portion 9A of the clam shell bucket 9. The opening and closing rope 40, which will be described later, is alternately wound around the upper sheave 9E and the lower sheave 9F of the clam shell bucket 9, and the other end 40B of the opening and closing rope 40 is attached to the bucket support portion 9A of the clam shell bucket 9.

[0016] The arm 10 is rotatably attached to the tip of the boom 6. As shown in FIG. 5, the arm 10 is formed of a hollow cylindrical body and is configured to be divisible by a base arm 11 extending in the front-rear direction, an upper guide arm 13 and a lower guide arm 14 detachably provided on the rear side of the base arm 11, and a sheave attachment member 15 movably attached to the upper guide arm 13 and the lower guide arm 14.

[0017] The base arm 11 serves as the base of the arm 10 and is formed as a square cylindrical body having a rectangular cross-sectional shape extending in the vertical direction. The base arm 11 is surrounded by a left side plate 11A, a right side plate 11B, a front upper surface plate 11C, a rear upper surface plate 11D, and a lower surface plate 11E. The left side plate 11A and the right side plate 11B are a pair of side plates facing each other in a direction (left-right direction) orthogonal to the length direction (front-rear direction) of the arm 10. The front upper surface plate 11C connects the upper ends of the front sides of the left side plate 11A and the right side plate 11B. The rear upper surface plate 11D connects the upper ends of the rear sides of the left side plate 11A and the right side plate 11B. The lower surface plate 11E connects the lower ends of the left side plate 11A and the right side plate 11B. The vertical height dimensions of the left side plate 11A and the right side plate 11B are set smaller on the front side than on the rear side. Therefore, a vertical step is formed at the boundary between the front upper surface plate 11C and the rear upper surface plate 11D.

[0018] The front end (one end in the length direction) of the base arm 11 is blocked by the front panel 11F, and the rear end (the other end in the length direction) 11G of the base arm 11 is an open end. A boom mounting bracket 11H and a cylinder mounting bracket 11J are provided on the lower face plate 11E of the base arm 11.

[0019] As shown in FIG. 11, the boom mounting bracket 11H is composed of two plate bodies facing each other at a fixed interval in the left-right direction. The left boom mounting bracket 11H is disposed at a position overlapping with the left side face plate 11A of the base arm 11 in the vertical direction, and the right boom mounting bracket 11H is disposed at a position overlapping with the right side face plate 11B of the base arm 11 in the vertical direction. The boom mounting bracket 11H is rotatably connected to the tip of the boom 6 via a boom connecting pin 11K (see FIG. 1). The cylinder mounting bracket 11J is pin-connected to the tip of an arm cylinder 8 whose base end is attached to the boom 6. Therefore, the base arm 11 rotates in the front-rear direction or the vertical direction around the boom connecting pin 11K according to the telescopic movement of the arm cylinder 8.

[0020] On the rear end sides of the left side face plate 11A and the right side face plate 11B, two pin insertion holes 11L and 11M penetrating in the left-right direction are formed at intervals in the vertical direction (see FIG. 5). An upper guide arm connecting pin 13B described later is inserted into the upper pin insertion hole 11L, and a lower guide arm connecting pin 14B described later is inserted into the lower pin insertion hole 11M. Further, on the front sides of the left side face plate 11A and the right side face plate 11B with respect to the pin insertion holes 11L and 11M, trunnion pin insertion holes 11N penetrating in the left-right direction are formed respectively (see FIG. 10). A cylinder support pin 17D described later is inserted into these two trunnion pin insertion holes 11N.

[0021] Here, the distance between the left side panel 11A and the right side panel 11B of the base arm 11 is set smaller on the front end side (one end in the longitudinal direction) of the base arm 11 than on the rear end side 11G side (the other end in the longitudinal direction) of the base arm 11 to which the lifting cylinder 17 is attached via the cylinder support pin 17D. Specifically, as shown in Figure 10, the left side panel 11A has a left rear side panel 11A1 located on the rear end side 11G of the base arm 11, and a left front side panel 11A2 located in front of the left rear side panel 11A1. The right side panel 11B has a right rear side panel 11B1 located on the rear end side 11G of the base arm 11, and a right front side panel 11B2 located in front of the right rear side panel 11B1. The distance A2 between the left front side panel 11A2 and the right front side panel 11B2 is set smaller than the distance A1 between the left rear side panel 11A1 and the right rear side panel 11B1. <A1)。

[0022] A bent plate 11P is fixed to the inner corner where the lower plate 11E and the front plate 11F of the base arm 11 intersect (see Figure 5). The bent plate 11P has a horizontal plate 11Q that faces the lower plate 11E at a certain distance, and a vertical plate 11R that is bent at a right angle from the horizontal plate 11Q toward the lower plate 11E. As a result, a cylinder holding portion 11S is formed at the inner corner where the front upper plate 11C and the front plate 11F of the base arm 11 intersect, surrounded by the left side plate 11A, the right side plate 11B, the front upper plate 11C, the front plate 11F, and the horizontal plate 11Q of the bent plate 11P. This cylinder holding portion 11S holds the bottom end of the lifting cylinder 17 mounted inside the base arm 11.

[0023] The reinforcing plate 12 is provided inside the base arm 11 and extends along the length of the base arm 11, connecting the left side panel 11A and the right side panel 11B. As shown in Figures 5 and 7, the reinforcing plate 12 is made of a separate component from the front upper panel 11C and the rear upper panel 11D of the base arm 11, and is formed from a single plate having a flat section 12A and an inclined section 12B. The flat section 12A is positioned between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B, and extends along the length of the base arm 11 while maintaining a constant distance between it and the rear upper panel 11D and the lower panel 11E. The inclined section 12B bends upward and backward from the flat section 12A and extends above the upper guide arm connecting pin 13B.

[0024] The front end 12C of the reinforcing plate 12 (flat plate portion 12A) is joined to the rear end of the front upper plate 11C, and the rear end 12D of the reinforcing plate 12 (inclined plate portion 12B) is joined to the rear end of the rear upper plate 11D. The bent portion 12E, which forms the boundary between the flat plate portion 12A and the inclined plate portion 12B, is located in the longitudinal direction of the base arm 11 between the attachment portion to the boom 6 (boom connecting pin 11K) and the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B. Specifically, the bent portion 12E is located adjacent to the front side of the cylinder support pin 17D, which will be described later.

[0025] In this manner, the reinforcing plate 12 connects the left side panel 11A and the right side panel 11B of the base arm 11. This prevents the left side panel 11A, to which the second lifting sheave 22 (described later) is attached, and the right side panel 11B, to which the second opening / closing sheave 30 (described later) is attached, from being deformed by external forces. Furthermore, the bent portion 12E of the reinforcing plate 12 is positioned adjacent to the front side of the cylinder support pin 17D, the inclined plate portion 12B of the reinforcing plate 12 extends from the flat plate portion 12A to the upper side of the upper guide arm connecting pin 13B, and the rear end 12D of the reinforcing plate 12 is joined to the rear end side of the rear upper panel 11D. As a result, a box structure 11T is formed on the rear end 11G side of the base arm 11, where the upper guide arm connecting pin 13B, lower guide arm connecting pin 14B, and cylinder support pin 17D are provided, defined by the left side panel 11A, the right side panel 11B, the rear upper panel 11D, the lower panel 11E, and the inclined plate portion 12B of the reinforcing plate 12 (see Figure 7).

[0026] The upper guide arm 13 and the lower guide arm 14 are detachably attached to the rear side of the base arm 11 in a pair in the vertical direction. The upper guide arm 13 and the lower guide arm 14 are each formed as rectangular tubular bodies with a rectangular cross-section and extend in the longitudinal direction (front-to-back direction) of the base arm 11. As shown in Figure 5, a cylindrical portion 13A extending in the left-to-right direction is fixed to the front end of the upper guide arm 13, and a cylindrical portion 14A extending in the left-to-right direction is fixed to the front end of the lower guide arm 14. An upper guide arm connecting pin 13B is inserted through the inner circumference of the cylindrical portion 13A of the upper guide arm 13, and both ends of the upper guide arm connecting pin 13B are inserted through the upper pin insertion holes 11L of the base arm 11. A lower guide arm connecting pin 14B is inserted through the inner circumference of the cylindrical portion 14A of the lower guide arm 14, and both ends of the lower guide arm connecting pin 14B are inserted through the lower pin insertion holes 11M of the base arm 11. On the other hand, the rear ends of the upper guide arm 13 and the lower guide arm 14 are connected via a connecting member 14C. As a result, the upper guide arm 13 and the lower guide arm 14 extend rearward from the rear end 11G of the base arm 11 while maintaining a constant distance between them in the vertical direction.

[0027] The sheave mounting member 15 is movably attached to the upper guide arm 13 and the lower guide arm 14. With the first lifting sheave 18 and the first opening / closing sheave 20 (described later) attached to the sheave mounting member 15, it moves in the front-rear direction along the upper guide arm 13 and the lower guide arm 14. The sheave mounting member 15 is formed as a cylindrical body having a rectangular cross-sectional shape equivalent to that of the base arm 11, and surrounds the upper guide arm 13 and the lower guide arm 14 from the outside. The sheave mounting member 15 is formed as a short cylindrical body (frame) surrounded by a left plate 15A, a right plate 15B, an upper plate 15C, and a lower plate 15D.

[0028] The front portions of the left plate 15A and the right plate 15B that constitute the sheave mounting member 15 each have pin insertion holes 15E that penetrate in the left-right direction (see Figure 5). Rod mounting pins 17F, which will be described later, are inserted through these two pin insertion holes 15E. The first lifting sheave shaft 19, which will be described later, is attached to the center of the left plate 15A that constitutes the sheave mounting member 15. The first opening / closing sheave shaft 21, which will be described later, is attached to the center of the right plate 15B that constitutes the sheave mounting member 15.

[0029] A slide plate 15F is provided between the inner surfaces of the left plate 15A, right plate 15B, and upper plate 15C of the sheave mounting member 15 and the upper guide arm 13, and the slide plate 15F is in slidable contact with the upper guide arm 13. A slide plate 15G is provided between the inner surfaces of the left plate 15A, right plate 15B, and lower plate 15D of the sheave mounting member 15 and the lower guide arm 14, and the slide plate 15G is in slidable contact with the lower guide arm 14. These slide plates 15F and 15G are fixed to the sheave mounting member 15 using bolts or the like, and allow the sheave mounting member 15 to move (slide) smoothly relative to the upper guide arm 13 and the lower guide arm 14.

[0030] The bucket lifting and opening / closing device 16 is installed on the arm 10. The bucket lifting and opening / closing device 16 controls various operations, including the lifting and lowering and opening / closing operations of the clamshell bucket 9. The bucket lifting and opening / closing device 16 consists of a lifting cylinder 17, a first lifting sheave 18, a first opening / closing sheave 20, a second lifting sheave 22, a second opening / closing sheave 30, an opening / closing cylinder 31, an intermediate guide sheave 37, a lifting rope 38, an opening / closing rope 40, a slack adjustment sheave 47, and a slack adjustment cylinder 48, which are described later.

[0031] The lifting cylinder 17 is located within the base arm 11 and extends in the longitudinal direction (front-to-back direction) of the base arm 11. The lifting cylinder 17 raises or lowers the clamshell bucket 9 by extending or retracting in response to the operation of an operating device located within the cab 4. The lifting cylinder 17 has a tube 17A, a piston (not shown) inserted within the tube 17A, and a rod 17B whose base end is attached to the piston and whose tip protrudes from the tube 17A.

[0032] A mounting flange 17C is fixed to the tube 17A of the lifting cylinder 17, and two pin holes (not shown) are formed concentrically on the mounting flange 17C, flanking the tube 17A. Two cylinder support pins 17D, which are inserted through trunnion pin insertion holes 11N of the base arm 11 (left side panel 11A and right side panel 11B), are fitted into these two pin holes. In this way, the tube 17A of the lifting cylinder 17 is connected to the base arm 11 via the cylinder support pins 17D.

[0033] On the other hand, a mounting eye 17E is provided at the tip of the rod 17B of the lifting cylinder 17. A rod mounting pin 17F is inserted through the mounting eye 17E and the pin insertion hole 15E of the sheave mounting member 15. In this way, the rod 17B of the lifting cylinder 17 is connected to the sheave mounting member 15 via the rod mounting pin 17F. Thus, the tube 17A of the lifting cylinder 17 is attached to the base arm 11 via the cylinder support pin 17D, and the rod 17B is attached to the sheave mounting member 15 via the rod mounting pin 17F. Consequently, by extending and retracting the lifting cylinder 17, the sheave mounting member 15 moves in the front-rear direction along the upper guide arm 13 and the lower guide arm 14.

[0034] As shown in Figures 5 and 6, a rectangular frame 17G is fixed to the bottom end of the lifting cylinder 17 (tube 17A), and the bottom end of the tube 17A is positioned within the cylinder holding portion 11S of the base arm 11 together with the frame 17G. The frame 17G is composed of two U-shaped frame members that sandwich the tube 17A radially, and has a cross-sectional shape that is slightly smaller than the cylinder holding portion 11S of the base arm 11. Multiple plate-shaped spacers 17H are attached to the outer surface of the frame 17G. These multiple spacers 17H are positioned between the left side plate 11A, the right side plate 11B, the front top plate 11C, and the bent plate 11P (horizontal plate 11Q) that constitute the cylinder holding portion 11S of the base arm 11 and the frame 17G. In this way, the bottom end of the lifting cylinder 17 is housed within the cylinder holding portion 11S of the base arm 11 via the frame 17G and the spacers 17H. This restricts the oscillation of the lifting cylinder 17 around the cylinder support pin 17D, thereby increasing the buckling strength of the lifting cylinder 17.

[0035] The first lifting sheave 18 is attached to the outer surface of the left plate 15A that constitutes the sheave mounting member 15 via the first lifting sheave shaft 19. The first lifting sheave shaft 19 is fixed to the center of the left plate 15A that constitutes the sheave mounting member 15. Multiple first lifting sheaves 18 are provided in the axial direction of the first lifting sheave shaft 19 (for example, five), and are supported by the sheave mounting member 15 so as to be rotatable about the first lifting sheave shaft 19.

[0036] The first opening / closing sheave 20 is attached to the outer surface of the right side plate 15B that constitutes the sheave mounting member 15 via the first opening / closing sheave shaft 21. The first opening / closing sheave shaft 21 is fixed to the center of the right side plate 15B that constitutes the sheave mounting member 15. Multiple first opening / closing sheaves 20 (for example, 5) are provided on the first opening / closing sheave shaft 21 in an axial direction and are supported on the sheave mounting member 15 so as to be rotatable about the first opening / closing sheave shaft 21.

[0037] The second lifting sheave 22 is provided on the base arm 11, spaced apart from the first lifting sheave 18. The second lifting sheave 22 is attached to the outer surface of the left side panel 11A (left front side panel 11A2) of the base arm 11 via the second lifting sheave bracket 23. As shown in Figures 7 and 8, the second lifting sheave bracket 23 consists of a base plate 23A, a plurality of first rib plates 23B, and a sheave cover 23C. The base plate 23A extends in the front-rear direction at a constant distance from the left side panel 11A of the base arm 11. The plurality (e.g., two) first rib plates 23B are arranged so as to straddle the second lifting sheave shaft 24 in the vertical direction and maintain a constant distance from each other, connecting the left side panel 11A of the base arm 11 and the base plate 23A. The upper of the two first rib plates 23B is welded to the left side panel 11A at a position where it overlaps with the flat plate portion 12A of the reinforcing plate 12 in a direction perpendicular to the longitudinal direction of the base arm 11 (left-right direction). The sheave cover 23C is formed in a frame shape that covers the multiple second lifting sheaves 22 from the outside and is attached to the base plate 23A.

[0038] The second lifting sheave shaft 24 is fixed to the base plate 23A of the second lifting sheave bracket 23 and is positioned between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B in the vertical direction of the base arm 11. The second lifting sheave shaft 24 supports the second lifting sheave 22 in a state where it is perpendicular to the longitudinal direction of the base arm 11 and protrudes away from the base arm 11 (to the left). Multiple (for example, four) second lifting sheaves 22 are provided in the axial direction of the second lifting sheave shaft 24 and are rotatably supported relative to the base arm 11 about the second lifting sheave shaft 24. Therefore, as the sheave mounting member 15 moves in accordance with the extension and retraction operation of the lifting cylinder 17, the first lifting sheave 18 attached to the sheave mounting member 15 moves closer to and further away from the second lifting sheave 22. The first lifting sheave 18 and the second lifting sheave 22 are wound with a lifting rope 38.

[0039] The opening / closing sheave moving mechanism 25 is located in the middle of the base arm 11 in the front-rear direction and is provided on the right side panel 11B (right front side panel 11B2). 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 Figures 3, 4, 11, etc., the opening / closing sheave moving mechanism 25 is composed of a guide rail 26, a sliding member 27, a second opening / closing sheave bracket 28, and a second opening / closing sheave shaft 29.

[0040] The guide rail 26 is formed from a rectangular flat plate extending in the longitudinal direction of the base arm 11 and is attached to the right side panel 11B of the base arm 11 via a plurality (e.g., two) second rib plates 26A. The second rib plates 26A are arranged so as to straddle the second opening / closing sheave shaft 29 in the vertical direction and maintain a constant distance from each other, connecting the right side panel 11B of the base arm 11 and the guide rail 26. As shown in Figure 8, the upper of the two second rib plates 26A is welded to the right side panel 11B at a position where it overlaps with the flat plate portion 12A of the reinforcing plate 12 in a direction perpendicular to the longitudinal direction of the base arm 11 (left-right direction). In addition, a reinforcing front end plate 26B is welded between the front ends of the guide rail 26 and the second rib plates 26A and the right side panel 11B. A reinforcing rear end plate 26C is welded between the rear end of the guide rail 26 and the second rib plate 26A and the right side plate 11B.

[0041] The front and rear sliding members 27 are each slidably engaged with the guide rail 26 in the longitudinal direction. The second opening / closing sheave bracket 28 is attached to the front and rear sliding members 27 using bolts or the like, and is movable along the guide rail 26 in the longitudinal direction of the base arm 11. The rod 31B of the opening / closing cylinder 31, which will be described later, is attached to the rear sliding member 27. The second opening / closing sheave shaft 29 is fixed to the second opening / closing sheave bracket 28 and is positioned between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B in the vertical direction of the base arm 11. The second opening / closing sheave shaft 29 supports the second opening / closing sheave 30 in a state where it is perpendicular to the longitudinal direction of the base arm 11 and protrudes away from the base arm 11 (to the right).

[0042] The second opening / closing sheave 30 is rotatably mounted on 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 that constitutes the base arm 11, so as to be movable in the front-rear direction via the opening / closing sheave moving mechanism 25. Multiple (for example, four) second opening / closing sheaves 30 are provided in the axial direction of the second opening / closing sheave shaft 29 provided on the opening / closing sheave moving mechanism 25, and are rotatably supported on the base arm 11 around the second opening / closing sheave shaft 29.

[0043] The opening / closing cylinder 31 is provided between the base arm 11 and the second opening / closing sheave 30. The opening / closing cylinder 31 extends in the longitudinal direction of the base arm 11 and moves the second opening / closing sheave 30 closer to and further away from the first opening / closing sheave 20. The opening / closing cylinder 31 has a tube 31A, a piston (not shown) inserted inside the tube 31A, and a rod 31B whose base end is attached to the piston and whose tip protrudes from the tube 31A. One end (bottom side) of the opening / closing cylinder 31 is attached to the rear end side of the right side face plate 11B that constitutes the base arm 11 via an opening / closing cylinder bracket 31C. The tip of the rod 31B is connected to a slide member 27 of the opening / closing sheave moving mechanism 25 and is attached to the second opening / closing sheave 30 via the opening / closing sheave moving mechanism 25. The second opening / closing sheave 30 moves in the front-rear direction in accordance with the extension and retraction operation of the opening / closing cylinder 31, moving closer to and further away from the first opening / closing sheave 20.

[0044] As shown in Figure 9, the opening / closing cylinder bracket 31C is composed of two plates facing each other in the vertical direction and is positioned between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B and the cylinder support pin 17D in the longitudinal direction of the base arm 11. Here, one end 31D (rear side) of the opening / closing cylinder bracket 31C in the longitudinal direction extends between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B while maintaining a constant distance in the vertical direction. On the other hand, the other end 31E (front side) of the opening / closing cylinder bracket 31C in the longitudinal direction has a shape in which the distance in the vertical direction gradually widens toward the cylinder support pin 17D. As a result, the other end 31E of the opening / closing cylinder bracket 31C is positioned adjacent to the cylinder support pin 17D above and below, reinforcing the area around the mounting portion (trunnion pin insertion hole 11N) of the base arm 11 for the cylinder support pin 17D.

[0045] The guide sheave support shaft 32 is provided on the front end side of the base arm 11. One end of the guide sheave support shaft 32 is fixed to the front end side of the left side panel 11A to which the front panel 11F is fixed, and the other end of the guide sheave support shaft 32 protrudes to the left from the left side panel 11A. The guide sheave support shaft 32 rotatably supports the lifting guide sheave 33 and the opening / closing guide sheave 34.

[0046] The lifting guide sheave 33 and the opening / closing guide sheave 34 are provided on the left side panel 11A of the base arm 11 via the guide sheave support shaft 32. The lifting guide sheave 33 guides the lifting rope 38, which is wound around the first lifting sheave 18 and the second lifting sheave 22, to the clamshell bucket 9. The opening / closing guide sheave 34 guides the opening / closing rope 40, which is wound around the first opening / closing sheave 20, the second opening / closing sheave 30, and the intermediate guide sheave 37 and slack adjustment sheave 47 (described later), to the clamshell bucket 9. As a result, as shown in Figure 1, for example, with the arm 10 held horizontally to the ground, the clamshell bucket 9 can be raised and lowered vertically using the lifting rope 38 wound around the lifting guide sheave 33 located at the front end of the arm 10.

[0047] The lifting guide sheave 33 and the opening / closing guide sheave 34 are positioned on the front end of the left side panel 11A of the base arm 11, where they are highly visible to the operator seated in the driver's seat 4A. This allows the operator to operate the bucket lifting / opening device 16 while visually confirming the status of the lifting rope 38 and opening / closing rope 40 attached to the clamshell bucket 9.

[0048] The intermediate guide sheave shaft 35 is located on the rear side of the front upper plate 11C that constitutes the base arm 11. A frame member 36, which is bent into a U-shape in cross-section, is fixed to the front upper plate 11C of the base arm 11. The intermediate guide sheave shaft 35 extends upward from the front upper plate 11C, slightly inclined toward the rear, with one end (lower end) attached to the front upper plate 11C and the other end (upper end) attached to the frame member 36.

[0049] The intermediate guide sheave 37 is rotatably mounted on the front upper plate 11C of the base arm 11 via the intermediate guide sheave shaft 35. The intermediate guide sheave 37 is interposed between the opening / closing guide sheave 34, which is provided on the left side plate 11A of the base arm 11, and the looseness adjustment sheave 47, which is provided on the right side plate 11B of the base arm 11. The opening / closing rope 40 extending from the looseness adjustment sheave 47 is wound around the intermediate guide sheave 37, guiding the opening / closing rope 40 to the opening / closing guide sheave 34.

[0050] 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 wire rope, and one end 38A of the lifting rope 38 is attached to a lifting rope mounting bracket 39 provided on the left side panel 11A of the base arm 11. The other end 38B of the lifting rope 38 is attached to the bucket support part 9A of the clamshell bucket 9, and supports the clamshell bucket 9 (see Figure 1). The middle section of the lifting rope 38 is alternately wound around multiple first lifting sheaves 18 and multiple second lifting sheaves 22.

[0051] As shown in Figures 7 and 10, the lifting rope mounting bracket 39 is provided on the left side panel 11A of the base arm 11, adjacent to the rear side of the second lifting sheave bracket 23, and extends in the front-rear direction. The lifting rope mounting bracket 39 has two plates 39A that face each other vertically at a certain distance apart, and an overhang 39B is provided on the front side of the plates 39A that extends to the left from the left side panel 11A. A joint 39D that can swing vertically around a pin 39C is attached to the overhang 39B. The joint 39D constitutes part of the lifting rope mounting bracket 39, and one end 38A of the lifting rope 38 is connected to it.

[0052] Here, the lifting rope mounting bracket 39 is welded to the base plate 23A of the second lifting sheave bracket 23 at its front, and to the left side panel 11A of the base arm 11 at its rear. In this way, the lifting rope mounting bracket 39 is integrally fixed to the second lifting sheave bracket 23. This configuration allows the load acting on the lifting rope 38 to be efficiently transmitted from the lifting rope mounting bracket 39 to the second lifting sheave bracket 23 and then to the base arm 11.

[0053] The opening / closing rope 40 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 40 is made of wire rope, and one end 40A of the opening / closing rope 40 is attached to an opening / closing rope mounting bracket 41 provided on the right side panel 11B of the base arm 11. The other end 40B of the opening / closing rope 40 is attached to the bucket support part 9A of the clamshell bucket 9 (see Figure 1). The middle section of the opening / closing rope 40 is alternately wound around multiple first opening / closing sheaves 20 and multiple second opening / closing sheaves 30. The other end 40B of the opening / closing rope 40 is alternately wound around multiple upper sheaves 9E and multiple lower sheaves 9F that make up the clamshell bucket 9.

[0054] As shown in Figures 9 and 10, the opening / closing rope mounting bracket 41 is provided on the right side plate 11B of the base arm 11, adjacent to the rear side of the opening / closing sheave movement mechanism 25, and extends in the front-rear direction. The opening / closing rope mounting bracket 41 consists of an upper plate 41A and a lower plate 41B that face each other vertically at a certain distance apart, and the front portion of the opening / closing rope mounting bracket 41 is welded to the rear end plate 26C of the guide rail 26 that constitutes the opening / closing sheave movement mechanism 25. An overhang portion 41C is provided on the front side of the opening / closing rope mounting bracket 41, extending to the right from the right side plate 11B, and a joint 41E that can swing vertically around a pin 41D is attached to the overhang portion 41C. The joint 41E constitutes part of the opening / closing rope mounting bracket 41, and one end 40A of the opening / closing rope 40 is connected to it. An opening / closing cylinder 31 is positioned between the upper plate 41A and the lower plate 41B of the opening / closing rope mounting bracket 41, protecting the opening / closing cylinder 31.

[0055] The clamshell bucket 9 descends when the lifting cylinder 17 retracts, causing the first lifting sheave 18 to move closer to the second lifting sheave 22, and rises when the lifting cylinder 17 extends, causing the first lifting sheave 18 to move away from the second lifting sheave 22. On the other hand, the clamshell bucket 9 opens when the opening / closing cylinder 31 retracts, causing the second opening / closing sheave 30 to move closer to the first opening / closing sheave 20, and closes when the opening / closing cylinder 31 extends, causing the second opening / closing sheave 30 to move away from the first opening / closing sheave 20.

[0056] The loosening adjustment sheave moving mechanism 42 is located on the front end side of the base arm 11 and is provided on the right side panel 11B. The loosening adjustment sheave moving mechanism 42 supports the loosening adjustment sheave 47 so that it can move in the front-rear direction. As shown in Figures 3 and 4, the loosening adjustment sheave moving mechanism 42 is composed of a guide rail 43, a sliding member 44, a loosening adjustment sheave bracket 45, and a loosening adjustment sheave shaft 46.

[0057] The guide rail 43 is fixed to the right side panel 11B of the base arm 11. The sliding member 44 is slidably engaged with the guide rail 43 in the longitudinal direction. The loosening adjustment sheave bracket 45 is attached to the sliding member 44 using bolts or the like. The rod 48B of the loosening adjustment cylinder 48, which will be described later, is attached to the loosening adjustment sheave bracket 45. The loosening adjustment sheave shaft 46 is also fixed to the loosening adjustment sheave bracket 45.

[0058] The loosening adjustment sheave 47 is rotatably mounted on the loosening adjustment sheave shaft 46 of the loosening adjustment sheave moving mechanism 42. That is, the loosening adjustment sheave 47 is mounted on the right side faceplate 11B of the base arm 11 so as to be movable in the front-rear direction via the loosening adjustment sheave moving mechanism 42. The loosening adjustment sheave 47 consists of a single sheave and is rotatably supported on the base arm 11 around the loosening adjustment sheave shaft 46.

[0059] The opening / closing rope 40, which is wound around multiple first opening / closing sheaves 20 and multiple second opening / closing sheaves 30, is then sequentially wound around a slack adjustment sheave 47, an intermediate guide sheave 37, and an opening / closing guide sheave 34. After the other end 40B of the opening / closing rope 40 wound around the opening / closing guide sheave 34 is wound around the upper sheave 9E and lower sheave 9F of the clamshell bucket 9, the other end 40B of the opening / closing rope 40 is attached to the bucket support part 9A.

[0060] The loosening adjustment cylinder 48 is located in front of the opening / closing sheave movement mechanism 25 and is provided on the right side plate 11B of the base arm 11. The loosening adjustment cylinder 48 extends in the front-rear direction and moves the loosening adjustment sheave 47 closer to or further away from the second opening / closing sheave 30. The loosening adjustment cylinder 48 has a tube 48A, a piston (not shown) inserted inside the tube 48A, and a rod 48B whose base end is attached to the piston and whose tip protrudes from the tube 48A.

[0061] One end (bottom side) of the loosening adjustment cylinder 48 is attached to the right side plate 11B of the base arm 11 via a loosening adjustment cylinder bracket 48C. The loosening adjustment cylinder bracket 48C is welded to the front end plate 26B of the guide rail 26 that constitutes the opening / closing sheave movement mechanism 25, and is integrally fixed to the guide rail 26. This configuration allows the load acting on the loosening adjustment sheave 47 to be efficiently transmitted to the base arm 11 via the loosening adjustment cylinder 48, loosening adjustment cylinder bracket 48C, guide rail 26, reinforcing plate 12, etc. The tip of the rod 48B is attached to the loosening adjustment sheave bracket 45 of the loosening adjustment sheave movement mechanism 42.

[0062] Therefore, the loosening adjustment sheave 47 attached to the loosening adjustment sheave moving mechanism 42 moves in the forward and backward direction in accordance with the extension and retraction operation of the loosening adjustment cylinder 48, moving closer to and further away from the second opening / closing sheave 30. For example, when excavating a shaft using the deep foundation drilling machine 1, when the clamshell bucket 9 lands on the ground and the opening / closing rope 40 is loosened, the loosening adjustment cylinder 48 is extended. This separates the loosening adjustment sheave 47 from the second opening / closing sheave 30, thereby removing the looseness from the opening / closing rope 40.

[0063] The deep foundation excavator 1 according to this embodiment has the configuration described above, and the operation of excavating a shaft using the deep foundation excavator 1 will be described below.

[0064] The operator, seated in the cab 4, operates the boom cylinder 7 to lift the tip of the boom 6 upward, as shown in Figure 1, for example, and operates the arm cylinder 8 to hold the arm 10 horizontal to the ground. Next, the clamshell bucket 9 is positioned above the ground where the shaft is to be excavated, and the lifting cylinder 17 is retracted. As a result, the sheave mounting member 15 moves forward along the upper guide arm 13 and the lower guide arm 14, the first lifting sheave 18 approaches the second lifting sheave 22, and the first opening / closing sheave 20 approaches the second opening / closing sheave 30. Consequently, the lifting rope 38 and the opening / closing rope 40 are fed out from the arm 10, and the clamshell bucket 9 descends.

[0065] As the clamshell bucket 9 approaches the ground, the operator 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 20, and the opening / closing rope 40 is fed out from the arm 10, causing the pair of buckets 9B of the clamshell bucket 9 to open fully. With the clamshell bucket 9 fully open, the operator retracts the lifting cylinder 17, causing the pair of buckets 9B of the clamshell bucket 9 to sink into the ground under their own weight.

[0066] Next, before closing the clamshell bucket 9, the operator extends the slack adjustment cylinder 48, separating the slack adjustment sheave 47, which is attached to the slack adjustment sheave moving mechanism 42, from the second opening / closing sheave 30. As a result, the lifting rope 38 remains slack, while only the slack in the opening / closing rope 40 is removed. In this state, the operator extends the opening / closing cylinder 31, separating the second opening / closing sheave 30, which is attached to the opening / closing sheave moving mechanism 25, from the first opening / closing sheave 20, thereby pulling the opening / closing rope 40 towards the arm 10. This causes the clamshell bucket 9 to close while sinking into the ground under its own weight, allowing it to scoop up a large amount of soil and sand.

[0067] After closing the clamshell bucket 9 and scooping up the soil, the operator extends the lifting cylinder 17. At this time, if the lifting rope 38 is loose after scooping up the soil, the operator extends the lifting cylinder 17 and simultaneously retracts the looseness adjustment cylinder 48. As a result, the first lifting sheave 18 attached to the sheave mounting member 15 separates from the second lifting sheave 22, and the lifting rope 38 is pulled up toward the arm 10, while the first opening / closing sheave 20 separates from the second opening / closing sheave 30, and the opening / closing rope 40 is pulled up toward the arm 10. As a result, the lifting rope 38 and the opening / closing rope 40 are pulled up toward the arm 10 together, and the clamshell bucket 9, holding the soil, is lifted and rises by the lifting rope 38 and the opening / closing rope 40.

[0068] After raising the clamshell bucket 9 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 retracts the opening / closing cylinder 31, bringing the second opening / closing sheave 30, which is attached to the opening / closing sheave moving mechanism 25, closer to the first opening / closing sheave 20. As a result, the opening / closing rope 40 is pulled out from the arm 10, and the clamshell bucket 9 opens, allowing the excavated soil to be discharged onto the bed of the dump truck.

[0069] In this way, after dumping soil 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 aforementioned work (operation).

[0070] In this embodiment, the deep foundation excavator 1 is provided with a reinforcing plate 12 inside the base arm 11 that connects the left side plate 11A and the right side plate 11B, thereby suppressing deformation of the left side plate 11A and the right side plate 11B due to external forces. Furthermore, since a part of the reinforcing plate 12 is positioned between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B, the base arm 11 can be made to have sufficient strength against external forces acting on the connection between the upper guide arm 13 and the lower guide arm 14 and the base arm 11. As a result, the strength of the base arm 11 can be increased and its lifespan can be extended.

[0071] Furthermore, the front end 12C of the reinforcing plate 12 (flat plate portion 12A) is joined to the rear end of the front upper plate 11C, and the rear end 12D of the reinforcing plate 12 (inclined plate portion 12B) is joined to the rear end of the rear upper plate 11D. The bent portion 12E, which forms the boundary between the flat plate portion 12A and the inclined plate portion 12B, is positioned in the longitudinal direction of the base arm 11 between the attachment portion to the boom 6 (boom connecting pin 11K) and the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B. This makes it possible to form a box structure portion 11T on the rear end 11G side of the base arm 11, defined by the left side plate 11A, the right side plate 11B, the rear upper plate 11D, the bottom plate 11E, and the inclined plate portion 12B of the reinforcing plate 12. As a result, the strength of the rear end 11G side of the base arm 11, which is provided with the upper guide arm connecting pin 13B, the lower guide arm connecting pin 14B, and the cylinder support pin 17D, can be increased.

[0072] On the other hand, the reinforcing plate 12 has a flat plate portion 12A that extends in the longitudinal direction of the base arm 11 and an inclined plate portion 12B that bends from the flat plate portion 12A toward the rear upper plate 11D, thereby improving the workability when installing the lifting cylinder 17 inside the base arm 11. Specifically, when inserting the lifting cylinder 17 from the rear end 11G of the base arm 11, which is the open end, with the lower plate 11E of the base arm 11 facing upward, the bottom side of the lifting cylinder 17 can be smoothly guided along the inclined plate portion 12B toward the flat plate portion 12A. Then, the lifting cylinder 17 is inserted into the base arm 11 along the flat plate portion 12A of the reinforcing plate 12. As a result, the frame 17G fixed to the bottom end of the lifting cylinder 17 (tube 17A) can be housed together with the spacer 17H inside the cylinder holding portion 11S of the base arm 11.

[0073] Furthermore, the distance between the left side panel 11A and the right side panel 11B that constitute the base arm 11 is set to be smaller on the front end side (one end side) of the base arm 11, where the front panel 11F is provided, compared to the rear end side 11G (other end side) of the base arm 11, where the lifting cylinder 17 is attached via the cylinder support pin 17D. This ensures that the necessary width dimension (distance A1 between the left rear side panel 11A1 and the right rear side panel 11B1) for attaching the lifting cylinder 17 can be secured at the rear end side 11G of the base arm 11. As a result, the width dimension (distance A2 between the left front side panel 11A2 and the right front side panel 11B2) of the part in front of the mounting part of the lifting cylinder 17 can be reduced, thus making the base arm 11 lighter.

[0074] Furthermore, a boom mounting bracket 11H, composed of two plates facing each other in the left-right direction, is fixed to the lower plate 11E of the base arm 11. The left boom mounting bracket 11H is positioned so as to overlap vertically with the left side plate 11A of the base arm 11. The right boom mounting bracket 11H is positioned so as to overlap vertically with the right side plate 11B of the base arm 11. This allows external forces transmitted from the boom 6 to the base arm 11 via the boom mounting brackets 11H to be efficiently transmitted to the left side plate 11A and the right side plate 11B. As a result, stress concentration at the joint between the boom mounting brackets 11H and the base arm 11 can be reduced. Furthermore, even if the left side panel 11A and the right side panel 11B of the base arm 11 do not overlap with the boom mounting bracket 11H, by positioning the left side panel 11A and the right side panel 11B and the boom mounting bracket 11H within a range of close proximity to each other (a range of no more than twice the thickness of the thicker of the two panels), external forces can be efficiently transmitted to the left side panel 11A and the right side panel 11B of the base arm 11.

[0075] Furthermore, at the inner corner where the front upper plate 11C and the front plate 11F of the base arm 11 intersect, a cylinder holding portion 11S is formed, surrounded by the left side plate 11A, the right side plate 11B, the front upper plate 11C, the front plate 11F, and the side plate 11Q of the bent plate 11P. This allows the bottom end of the lifting cylinder 17, which is attached to the base arm 11 via the cylinder support pin 17D, to be housed within the cylinder holding portion 11S. As a result, the oscillation of the lifting cylinder 17 around the cylinder support pin 17D is restrained, and the buckling strength of the lifting cylinder 17 can be increased. Moreover, if the dimensional accuracy of the cylinder holding portion 11S that houses the bottom end of the lifting cylinder 17 is ensured, the dimensional tolerances of other parts can be set larger, which reduces the assembly man-hours of the base arm 11 and contributes to reducing manufacturing costs.

[0076] Furthermore, the arm 10 is configured to be separable, consisting of a base arm 11, an upper guide arm 13 and a lower guide arm 14, and a sheave mounting member 15. Therefore, even in narrow work sites such as indoor sites where space for transporting the deep foundation excavator 1 cannot be secured, the arm 10 can be removed from the boom 6, the removed arm 10 can be separated and loaded onto a relatively small transport vehicle, transported to the work site, and then assembled at the work site. In addition, the overall length of the arm 10 can be appropriately set by changing the lengths of the upper guide arm 13 and the lower guide arm 14. As a result, if the length of the upper guide arm 13 and the lower guide arm 14 is increased to increase the overall length of the arm 10, the excavation depth of the shaft by the deep foundation excavator 1 can be increased. On the other hand, if the length of the upper guide arm 13 and the lower guide arm 14 is reduced to reduce the overall length of the arm 10, the arm 10 can be made lighter, improving transportability.

[0077] Furthermore, as shown in Figure 8, the first rib plate 23B of the second lifting sheave bracket 23 is fixed to the left side panel 11A of the base arm 11, and the second lifting sheave shaft 24 that supports the second lifting sheave 22 is attached to the second lifting sheave bracket 23. The upper of the two first rib plates 23B is welded to the left side panel 11A at a position where it overlaps with the flat plate portion 12A of the reinforcing plate 12 in a direction perpendicular to the longitudinal direction of the base arm 11. As a result, the external force acting on the left side panel 11A of the base arm 11 from the second lifting sheave 22 is transmitted to the reinforcing plate 12 via the first rib plate 23B, thereby suppressing deformation of the left side panel 11A. Furthermore, even if the first rib plate 23B and the reinforcing plate 12 (flat plate portion 12A) do not overlap, external forces can be transmitted to the reinforcing plate 12 via the first rib plate 23B by arranging the first rib plate 23B and the reinforcing plate 12 within a range of close proximity to each other (the distance between them being no more than twice the thickness of the first rib plate 23B, which has a larger plate thickness). In other words, for example, the second lifting sheave bracket 23 only needs to have multiple first rib plates 23B, and the second lifting sheave shaft 24 can be attached to the second lifting sheave bracket 23, which has these first rib plates 23B fixed to the left side panel 11A.

[0078] Furthermore, a guide rail 26 for an opening / closing sheave movement mechanism 25, which moves the second opening / closing sheave 30 in the longitudinal direction of the base arm 11, is attached to the right side panel 11B of the base arm 11 via a second rib plate 26A. The upper of the two second rib plates 26A is welded to the right side panel 11B at a position where it overlaps with the flat plate portion 12A of the reinforcing plate 12 in a direction perpendicular to the longitudinal direction of the base arm 11. As a result, the external force acting on the right side panel 11B of the base arm 11 from the second opening / closing sheave 30 is transmitted to the reinforcing plate 12 via the second rib plate 26A, thereby suppressing deformation of the right side panel 11B. Furthermore, even if the second rib plate 26A and the reinforcing plate 12 (flat plate portion 12A) do not overlap, external forces can be transmitted to the reinforcing plate 12 via the second rib plate 26A by arranging the second rib plate 26A and the reinforcing plate 12 within a range of close proximity to each other (the distance between them being no more than twice the thickness of the thicker second rib plate 26A). In other words, for example, the guide rail 26 only needs to be attached to multiple second rib plates 26A fixed to the right side panel 11B.

[0079] Here, the flat portion 12A of the reinforcing plate 12 is positioned between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B, which are provided at the rear end 11G of the base arm 11. For this reason, the upper first rib plate 23B and the upper second rib plate 26A are also positioned between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B. On the other hand, the second lifting sheave shaft 24 that supports the second lifting sheave 22 and the second opening / closing sheave shaft 29 that supports the second opening / closing sheave 30 are positioned between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B in the vertical direction of the base arm 11. This allows the load acting on the second lifting sheave 22 and the load acting on the second opening / closing sheave 30 to be efficiently transmitted to the reinforcing plate 12 via the first rib plate 23B and the second rib plate 26A. As a result, stress concentration on the base arm 11 can be reduced, and the overall weight of the base arm 11 can be reduced by reducing the thickness of each plate material that makes up the base arm 11.

[0080] Furthermore, as shown in Figure 10, the lifting rope mounting bracket 39 to which one end 38A of the lifting rope 38 is attached is integrally fixed to the base plate 23A of the second lifting sheave bracket 23. This allows the load acting on the lifting rope 38 to be efficiently transmitted from the lifting rope mounting bracket 39 to the base arm 11 via the second lifting sheave bracket 23. As a result, stress concentration at the joint between the lifting rope mounting bracket 39 and the base arm 11 can be reduced. Moreover, compared to, for example, the case where the lifting rope mounting bracket 39 is positioned at a distance from the base plate 23A of the second lifting sheave bracket 23, the length dimension on the rear end 11G side of the base arm 11 (length dimension from boom connecting pin 11K to rear end 11G) can be shortened.

[0081] Furthermore, as shown in Figure 9, the opening / closing cylinder bracket 31C, which supports the bottom side of the opening / closing cylinder 31, is positioned in the longitudinal direction of the base arm 11 between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B and the cylinder support pin 17D. This allows the length dimension of the rear end 11G side of the base arm 11 to be shortened compared to, for example, the case where the opening / closing cylinder bracket 31C is attached in front of the cylinder support pin 17D. Moreover, by fixing the opening / closing cylinder bracket 31C around the upper guide arm connecting pin 13B, the lower guide arm connecting pin 14B and the cylinder support pin 17D, the strength of the rear end 11G side of the base arm 11, which is the open end, can be increased.

[0082] In this case, the other end 31E (front side) of the opening / closing cylinder bracket 31C in the longitudinal direction has a shape in which the vertical spacing gradually widens toward the cylinder support pin 17D. This allows the other end 31E of the opening / closing cylinder bracket 31C to be positioned adjacent to the cylinder support pin 17D above and below, and the area around the mounting portion of the cylinder support pin 17D on the base arm 11 can be reinforced.

[0083] Furthermore, a mounting bracket 41 for the opening / closing rope, having an upper plate 41A and a lower plate 41B that face each other in the vertical direction, is provided on the rear side of the opening / closing sheave movement mechanism 25, and the opening / closing cylinder 31 is positioned between the upper plate 41A and the lower plate 41B of the opening / closing rope mounting bracket 41. This allows the opening / closing cylinder 31 to be protected from interference caused by the swing of the opening / closing rope 40 by the opening / closing rope mounting bracket 41.

[0084] Furthermore, as shown in Figures 3 and 4, the loosening adjustment cylinder bracket 48C to which one end (bottom side) of the loosening adjustment cylinder 48 is attached is integrally fixed to the guide rail 26 that constitutes the opening / closing sheave movement mechanism 25. This allows the load acting on the loosening adjustment sheave 47 to be efficiently transmitted to the base arm 11 via the loosening adjustment cylinder 48, loosening adjustment cylinder bracket 48C, guide rail 26, reinforcing plate 12, etc. As a result, stress concentration at the joint between the loosening adjustment cylinder bracket 48C and the base arm 11 can be reduced. In addition, the length dimension of the rear end 11G side of the base arm 11 can be shortened compared to, for example, the case where the loosening adjustment cylinder bracket 48C is positioned in front of the guide rail 26.

[0085] Thus, in this embodiment, the working device 5 of the deep foundation excavator 1 comprises a base arm 11 on which a clamshell bucket 9 is positioned at one end in the longitudinal direction, an upper guide arm 13 and a lower guide arm 14 connected to the other end of the base arm 11 via an upper guide arm connecting pin 13B and a lower guide arm connecting pin 14B, a first lifting sheave 18 and a first opening / closing sheave 20, a lifting cylinder 17, a second lifting sheave 22 and a second opening / closing sheave 30, a lifting rope 38, and an opening / closing rope 40. The base arm 11 is formed as a cylindrical body with a left side panel 11A and a right side panel 11B that are spaced apart and facing each other in a direction perpendicular to the longitudinal direction. The second lifting sheave shaft 24 and the second opening / closing sheave shaft 29 are positioned between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B in the vertical direction of the base arm 11. The base arm 11 is provided with a reinforcing plate 12 that extends in the longitudinal direction of the base arm 11 while connecting the left side panel 11A and the right side panel 11B. A portion of the reinforcing plate 12 is positioned between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B in the vertical direction of the base arm 11.

[0086] With this configuration, a portion of the reinforcing plate 12 connecting the left side panel 11A and the right side panel 11B is positioned between the upper guide arm connecting pin 13B and the lower arm connecting pin 14B, thereby suppressing deformation of the left side panel 11A and the right side panel 11B due to external forces. As a result, the base arm 11 can be made to have sufficient strength against external forces acting on the connection between the upper guide arm 13 and the lower guide arm 14 and the base arm 11, thereby extending its lifespan.

[0087] In this embodiment, the base arm 11 is rotatably attached to the tip of the boom 6 which is attached to the upper slewing body 3. The reinforcing plate 12 has a flat plate portion 12A that is positioned between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B and extends in the longitudinal direction of the base arm 11, and an inclined plate portion 12B that bends from the flat plate portion 12A and extends upward toward the upper side of the upper guide arm connecting pin 13B. The bent portion 12E, which is the boundary between the flat plate portion 12A and the inclined plate portion 12B, is positioned in the longitudinal direction of the base arm 11 between the attachment portion to the boom 6 (boom connecting pin 11K) and the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B. With this configuration, a box structure portion 11T can be formed at the rear end 11G side of the base arm 11, defined by the inclined plate portion 12B of the reinforcing plate 12. As a result, the strength of the rear end 11G side of the base arm 11, which is provided with the upper guide arm connecting pin 13B, the lower guide arm connecting pin 14B, and the cylinder support pin 17D, can be increased.

[0088] In this embodiment, the lifting cylinder 17 is located on the other end (rear end 11G) in the longitudinal direction of the base arm 11 and is attached to the left side panel 11A and the right side panel 11B that constitute the base arm 11 via a cylinder support pin 17D. The distance between the left side panel 11A and the right side panel 11B of the base arm 11 is set to be smaller on one end of the base arm 11 (the distance between the left front side panel 11A2 and the right front side panel 11B2) than on the other end of the base arm 11 to which the lifting cylinder 17 is attached (the distance between the left rear side panel 11A1 and the right rear side panel 11B1). With this configuration, the width dimension of the part of the base arm 11 that is in front of the mounting part of the lifting cylinder 17 (cylinder support pin 17D) can be reduced, and the weight of the base arm 11 can be reduced.

[0089] In this embodiment, the base arm 11 has a boom mounting bracket 11H that is rotatably attached to the tip of the boom 6 which is attached to the upper slewing body 3. The boom mounting bracket 11H is positioned to overlap vertically with the left side panel 11A and the right side panel 11B that constitute the base arm 11. With this configuration, external forces transmitted from the boom 6 to the base arm 11 via the boom mounting bracket 11H can be efficiently transmitted to the left side panel 11A and the right side panel 11B. As a result, stress concentration at the joint between the boom mounting bracket 11H and the base arm 11 can be reduced.

[0090] In this embodiment, a lifting cylinder 17 is rotatably mounted on the other end of the base arm 11 in the longitudinal direction via a cylinder support pin 17D, and a cylinder holding portion 11S is provided on one end of the base arm 11 in the longitudinal direction to hold the bottom end of the lifting cylinder 17 in a restrained state. With this configuration, by housing the bottom end of the lifting cylinder 17 within the cylinder holding portion 11S, the swinging of the lifting cylinder 17 around the cylinder support pin 17D is restrained, and the buckling strength of the lifting cylinder 17 can be increased.

[0091] In this embodiment, the second lifting sheave shaft 24 is attached to a second lifting sheave bracket 23 having a plurality of first rib plates 23B fixed to the left side panel 11A that constitutes the base arm 11. This configuration makes it possible to suppress deformation of the left side panel 11A.

[0092] In this embodiment, the second opening / closing sheave shaft 29 is attached to a second opening / closing sheave bracket 28 that moves along a guide rail 26 extending in the longitudinal direction of the base arm 11, and the guide rail 26 is attached to a plurality of second rib plates 26A fixed to the right side panel 11B that constitutes the base arm 11. With this configuration, deformation of the right side panel 11B can be suppressed.

[0093] In this embodiment, the base arm 11 is provided with a lifting rope mounting bracket 39 to which one end 38A of the lifting rope 38 is attached, and the lifting rope mounting bracket 39 is integrally fixed to the second lifting sheave bracket 23. With this configuration, the load acting on the lifting rope 38 can be efficiently transmitted from the lifting rope mounting bracket 39 to the base arm 11 via the second lifting sheave bracket 23. As a result, stress concentration at the joint between the lifting rope mounting bracket 39 and the base arm 11 can be reduced.

[0094] In this embodiment, a lifting cylinder 17 is attached to the other end of the base arm 11 in the longitudinal direction via a cylinder support pin 17D. Between the base arm 11 and the second opening / closing sheave 30, an opening / closing cylinder 31 is provided, one end of which is connected to the base arm 11 via an opening / closing cylinder bracket 31C and the other end of which is connected to the second opening / closing sheave 30. This cylinder 31 moves the second opening / closing sheave 30 closer to and further away from the first opening / closing sheave 20. The opening / closing cylinder bracket 31C is positioned between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B and the cylinder support pin 17D in the longitudinal direction of the base arm 11. With this configuration, the strength of the other end of the base arm 11 in the longitudinal direction can be increased by the opening / closing cylinder bracket 31C fixed around the upper guide arm connecting pin 13B, the lower guide arm connecting pin 14B and the cylinder support pin 17D.

[0095] In this embodiment, the opening / closing cylinder bracket 31C is composed of two plates facing each other in the vertical direction. One end 31D in the longitudinal direction extends between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B while maintaining a constant distance in the vertical direction, while the other end 31E in the longitudinal direction widens in the vertical direction toward the cylinder support pin 17D. With this configuration, the other end 31E of the opening / closing cylinder bracket 31C can be positioned adjacent to the cylinder support pin 17D above and below, and the area around the mounting portion of the cylinder support pin 17D on the base arm 11 can be reinforced.

[0096] In this embodiment, the base arm 11 is provided with an opening / closing rope mounting bracket 41 having an upper plate 41A and a lower plate 41B that face each other in the vertical direction, to which one end 40A of the opening / closing rope 40 is attached, and the opening / closing cylinder 31 is positioned between the upper plate 41A and the lower plate 41B of the opening / closing rope mounting bracket 41. With this configuration, the opening / closing cylinder 31 can be protected from interference caused by the swing of the opening / closing rope 40 by using the opening / closing rope mounting bracket 41.

[0097] In this embodiment, the base arm 11 is provided with a loosening adjustment sheave 47 around which an opening / closing rope 40 is wound and which is movable in a direction approaching and moving away from the second opening / closing sheave 30, and a loosening adjustment cylinder 48 that moves the loosening adjustment sheave 47. The second opening / closing sheave shaft 29 is attached to a second opening / closing sheave bracket 28 which moves along a guide rail 26 extending in the longitudinal direction of the base arm 11, and a loosening adjustment cylinder bracket 48C that supports one end of the loosening adjustment cylinder 48 is integrally fixed to the guide rail 26. With this configuration, the load acting on the loosening adjustment sheave 47 can be efficiently transmitted to the base arm 11 via the loosening adjustment cylinder 48, the loosening adjustment cylinder bracket 48C, the guide rail 26, the reinforcing plate 12, etc. As a result, stress concentration at the joint between the loosening adjustment cylinder bracket 48C and the base arm 11 can be reduced.

[0098] In this embodiment, a reinforcing plate 12, made of a separate material from the front upper plate 11C and rear upper plate 11D of the base arm 11, is shown as a reinforcing plate connecting the left side panel 11A and the right side panel 11B of the base arm 11. However, the present invention is not limited to this, and for example, as shown in the modified examples in Figures 12 and 13, the upper plate 52 of the base arm 51 may be made of a reinforcing plate. That is, the modified base arm 51 is formed as a rectangular tube having a left side panel 51A, a right side panel 51B, a bottom panel 51C, a front panel 51D, etc., and the upper plate 52 connecting the upper end of the left side panel 51A and the upper end of the right side panel 51B, which are a pair of side panels, constitutes the reinforcing plate in this modified example.

[0099] The top plate 52 of the base arm 51 is positioned between the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B. The top plate 52 has a flat plate portion 52A that extends in the longitudinal direction of the base arm 51 while maintaining a constant distance from the bottom plate 51C, and an inclined plate portion 52B that bends rearward and upward from the flat plate portion 52A and extends above the upper guide arm connecting pin 13B. The bent portion 52C, which is the boundary between the flat plate portion 52A and the inclined plate portion 52B, is positioned in the longitudinal direction of the base arm 51 between the mounting portion to the boom 6 (boom connecting pin 11K) and the upper guide arm connecting pin 13B and the lower guide arm connecting pin 14B. The upper first rib plate 23B, which is fixed to the base plate 23A of the second lifting sheave bracket 23, is fixed to the left side plate 51A of the base arm 51 at a position where it overlaps with the top plate 52 in the left-right direction perpendicular to the longitudinal direction of the base arm 51. Furthermore, the upper second rib plate 26A, which is fixed to the guide rail 26 of the opening / closing sheave movement mechanism 25, is fixed to the right side plate 51B of the base arm 51 at a position where it overlaps with the top plate 52 (flat plate portion 52A) in the left-right direction.

[0100] The modified base arm 51 is equipped with an upper plate 52 as a reinforcing plate connecting the left side plate 51A and the right side plate 51B, and its basic function is not particularly different from the base arm 11 in the embodiment equipped with a reinforcing plate 12. However, by constructing the upper plate 52 with a reinforcing plate, the modified base arm 51 can be made slimmer by reducing its vertical dimensions, thereby reducing weight and cost.

[0101] In this embodiment, the reinforcing plate 12 is shown as being formed from a single plate fixed to the left side panel 11A and the right side panel 11B of the base arm 11. However, the present invention is not limited to this, and for example, two plates, one fixed to the left side panel 11A and the other to the right side panel 11B of the base arm 11, may be connected at the intermediate part in the left-right direction of the base arm 11. That is, for example, the base arm 11 only needs to have a reinforcing plate 12 that is fixed to at least one of the side panels of the left side panel 11A and the right side panel 11B and extends in the longitudinal direction of the base arm 11.

[0102] Furthermore, in the embodiment, an example is shown in which the base arm 11 is constructed from a rectangular cylindrical body having a rectangular cross-sectional shape. However, the present invention is not limited to this, and the base arm may be formed using a cylindrical body having a polygonal cross-sectional shape other than a rectangle, for example, having a pair of opposing side plates. [Explanation of Symbols]

[0103] 1. Deep foundation drilling machine 2. Lower running body (vehicle body) 3. Upper rotating body (vehicle body) 5. Working equipment 6 Boom 9 Clamshell Bucket 10 Arms 11.51 Base Arm 11A,51A Left side plate (side plate) 11B,51B Right side plate (side plate) 11H Boom Mounting Bracket 11K Boom Connecting Pin (Mounting part for the boom) 11S Cylinder retaining part 12 Reinforcement plate 12A,52A flat plate part 12B,52B Inclined plate part 12E,52C Bend part 13 Upper guide arm 13B Upper guide arm connecting pin 14 Lower guide arm 14B Lower guide arm connecting pin 17 Lifting Cylinder 17D Cylinder support pin 18. First lifting sheave 20. First opening / closing sheave 22 Second lifting sheave 23. Second lifting sheave bracket 23B First Rib Plate 24. Second lifting sheave shaft (sheave shaft) 26 Guide rails 26A Second Rib Plate 28. Second opening / closing sheave bracket 29. Second opening / closing sheave shaft (sheave shaft) 30. Second opening / closing sheave 31 Opening / Closing Cylinder 31C Opening / Closing Cylinder Bracket 38 Lifting rope 38A one end 39. Lifting rope mounting bracket 40 Opening / Closing Rope 41. Bracket for attaching opening / closing rope 41A Top plate 41B Lower plate 47. Sheave for adjusting looseness 48. Looseness adjustment cylinder 48C Loosening adjustment cylinder bracket 52 Top plate (reinforcement plate)

Claims

1. It consists of a self-propelled vehicle body and a work device installed on the vehicle body. The work device includes a base arm that is rotatably mounted on the vehicle body and has a clamshell bucket positioned at one end in the longitudinal direction so as to be able to move up and down, An upper guide arm and a lower guide arm are connected to the other end of the base arm at a constant distance in the vertical direction via an upper guide arm connecting pin and a lower guide arm connecting pin, and the upper guide arm and lower guide arm extend in the longitudinal direction of the base arm, A first lifting sheave and a first opening / closing sheave are provided to be movable along the upper guide arm and the lower guide arm, A lifting cylinder attached to the base arm for moving the first lifting sheave and the first opening / closing sheave, A second lifting sheave and a second opening / closing sheave are spaced apart from the first lifting sheave and the first opening / closing sheave, and are rotatably mounted on the base arm about the sheave axis, A lifting rope is wound around the first lifting sheave and the second lifting sheave to raise and lower the clamshell bucket, A deep foundation drilling machine comprising a first opening / closing sheave and a second opening / closing sheave, and an opening / closing rope that is wound around them to open and close the clamshell bucket, The base arm is formed as a cylindrical body having a pair of side plates that are spaced apart and facing each other in a direction perpendicular to the longitudinal direction. The sheave shafts of the second lifting sheave and the second opening / closing sheave are positioned between the upper guide arm connecting pin and the lower guide arm connecting pin in the vertical direction of the base arm. The deep foundation excavator is characterized in that the base arm is provided with a reinforcing plate fixed to at least one of the pair of side plates and extending in the longitudinal direction of the base arm, and a portion of the reinforcing plate is positioned between the upper guide arm connecting pin and the lower guide arm connecting pin in the vertical direction of the base arm.

2. The base arm is rotatably attached to the tip of the boom mounted on the vehicle body. The reinforcing plate has a flat plate portion that is positioned between the upper guide arm connecting pin and the lower guide arm connecting pin and extends in the longitudinal direction of the base arm, and an inclined plate portion that is bent from the flat plate portion and extends toward the upper side of the upper guide arm connecting pin. The deep foundation excavator according to claim 1, characterized in that the bent portion which forms the boundary between the flat plate portion and the inclined plate portion is located between the mounting portion to the boom and the upper guide arm connecting pin and the lower guide arm connecting pin in the longitudinal direction of the base arm.

3. The lifting cylinder is located on the other end of the base arm in the longitudinal direction and is attached to the pair of side plates constituting the base arm via a cylinder support pin. The deep foundation excavator according to claim 1, characterized in that the distance between the pair of side plates of the base arm is set to be smaller on one end of the base arm than on the other end of the base arm to which the lifting cylinder is attached.

4. The base arm has a boom mounting bracket that is rotatably attached to the tip of the boom attached to the vehicle body, The deep foundation excavator according to claim 1, characterized in that the boom mounting bracket is positioned to overlap in the vertical direction with the pair of side plates constituting the base arm.

5. The lifting cylinder is rotatably mounted on the other end of the base arm in the longitudinal direction via a cylinder support pin. The deep foundation drilling machine according to claim 1, characterized in that a cylinder holding portion is provided at one end of the base arm in the longitudinal direction for holding the bottom end of the lifting cylinder in a restrained state.

6. The deep foundation excavator according to claim 1, characterized in that the sheave shaft of the second lifting sheave is attached to a second lifting sheave bracket having a plurality of first rib plates fixed to one of the pair of side plates constituting the base arm.

7. The sheave shaft of the second opening / closing sheave is attached to a second opening / closing sheave bracket that moves along a guide rail extending in the longitudinal direction of the base arm. The deep foundation excavator according to claim 6, characterized in that the guide rail is attached to a plurality of second rib plates fixed to the other side plate of the pair of side plates constituting the base arm.

8. The base arm is provided with a lifting rope mounting bracket to which one end of the lifting rope is attached. The deep foundation excavator according to claim 6, characterized in that the lifting rope mounting bracket is integrally fixed to the second lifting sheave bracket.

9. The lifting cylinder is attached to the other end of the base arm in the longitudinal direction via a cylinder support pin. Between the base arm and the second opening / closing sheave, there is an opening / closing cylinder, one end of which is connected to the base arm via an opening / closing cylinder bracket and the other end of which is connected to the second opening / closing sheave, which moves the second opening / closing sheave closer to and further away from the first opening / closing sheave. The deep foundation excavator according to claim 1, characterized in that the opening and closing cylinder bracket is positioned between the upper guide arm connecting pin and the lower guide arm connecting pin and the cylinder support pin in the longitudinal direction of the base arm.

10. The deep foundation drilling machine according to claim 9, wherein the opening and closing cylinder bracket is composed of two plates facing each other in the vertical direction, one end in the longitudinal direction extends between the upper guide arm connecting pin and the lower guide arm connecting pin while maintaining a constant distance in the vertical direction, and the other end in the longitudinal direction widens in the vertical direction toward the cylinder support pin.

11. The base arm is provided with an opening / closing rope mounting bracket having an upper plate and a lower plate facing each other in the vertical direction, to which one end of the opening / closing rope is attached. The deep foundation excavator according to claim 9, characterized in that the opening / closing cylinder is positioned between the upper plate and the lower plate of the opening / closing rope mounting bracket.

12. The base arm is provided with a looseness adjustment sheave around which the opening and closing rope is wound and which is movable in a direction toward and toward the second opening and closing sheave, and a looseness adjustment cylinder for moving the looseness adjustment sheave. The sheave shaft of the second opening / closing sheave is attached to a second opening / closing sheave bracket that moves along a guide rail extending in the longitudinal direction of the base arm. The deep foundation drilling machine according to claim 1, characterized in that the loosening adjustment cylinder bracket supporting one end of the loosening adjustment cylinder is integrally fixed to the guide rail.

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