Lower leader attachment / detachment jig for pile driving machine and method of use thereof

Abstract

To provide a lower leader detaching tool of a pile driver and an application method thereof allowing simple and easy handling.SOLUTION: A lower leader detaching tool 31 of a pile driver detachably provided with a lower leader 20 by fastening a flange with a plurality of bolts on a lower end flange surface of a leader 19 guiding lifting of a work device 17 comprises: a bracket 32 detachably provided on the lower leader 20; and a suspension tool 33 connecting between the bracket 32 and the work device 17 to make the lower leader 20 follow lifting motion along a vertical direction of the work device 17, wherein the bracket 32 has a suspension tool attaching part 38 on which the suspension tool 33 is attached to hold the lower leader 20 in a suspended posture where an upper flange surface (an upper surface of a flange 20a) faces the lower flange surface (a lower surface of a flange 19a) of the leader 19 in a state that the tension is applied to the suspension tool 33.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a lower leader attaching / detaching jig for a pile driver and a method of using the same, and more particularly, to a lower leader attaching / detaching jig for a pile driver used when attaching and detaching a lower leader to and from the lower end of a leader, and a method of using the same. [Background Art]

[0002] In a pile driver provided with a working device that applies rotation and pushing force to a construction member for pile construction (such as a steel pipe pile, a rod, etc.), a lower leader is detachably provided at the lower end of a leader that guides the working device. When the lower leader is attached, the lifting stroke of the working device can be increased; on the other hand, when the lower leader is removed, the corresponding space can be utilized to increase the diameter of the lower end (blade) of the construction member. Pile drivers capable of such specification change require unstable attaching / detaching work performed while the lower leader is suspended by a crane. Therefore, instead of a crane suspension rope, a lower leader attaching / detaching jig that lifts and lowers the lower leader by a hydraulic jack has been developed and put into use (see, for example, Patent Document 1). [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2016-98622 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] However, the lower leader attaching / detaching jig described in Patent Document 1 requires a large amount of preliminary setup time necessary for supporting the lower leader, similarly to conventional crane work, and furthermore, it is necessary to exercise caution in the operation of the hydraulic jack from the viewpoint of preventing pinching. In particular, on-site demand for a simple lower leader attaching / detaching jig that does not require dedicated power is still high, and at various sites where pile drivers are used, there continues to be demand for the development of a lower leader attaching / detaching jig that can be easily handled.

[0005] Therefore, the present invention aims to provide a simple and easy-to-handle lower leader attachment / detachment jig for a pile driver and a method for using the same. [Means for solving the problem]

[0006] To achieve the above objective, the lower leader attachment / detachment jig for a pile driver of the present invention is a lower leader attachment / detachment jig for a pile driver in which a lower leader is attached and detachably to the lower end flange surface of a leader that guides the working device up and down by flange fastening with a plurality of bolts, comprising a bracket attached to the lower leader and a suspension device that connects the bracket and the working device and causes the lower leader to follow the up and down movement of the working device in the vertical direction, wherein the bracket has a suspension device attachment portion to which the suspension device is attached, and the lower leader is held in a suspended position in which its upper end flange surface faces the lower end flange surface of the leader while tension is applied to the suspension device.

[0007] Furthermore, the device is equipped with a tension display unit for monitoring the magnitude of the tension applied to the lifting device, and the tension display unit is characterized by being a suspension scale used by being interposed between the lifting device and the lifting device mounting unit.

[0008] Furthermore, the suspension mounting section comprises a shaft to which the suspension is attached, a shaft support structure that movably supports the shaft, and a warning display section that indicates when the amount of tension applied to the suspension exceeds a set value; the shaft support structure comprises a plate with a through hole through which the shaft passes, and an expandable and contractible spring that elastically prevents the shaft from coming out of the through hole; and the warning display section is an indicator provided on the circumferential surface of the shaft that appears and disappears on the plate surface of the plate in accordance with the relative movement between the shaft and the plate.

[0009] Furthermore, the method of using the lower leader attachment / detachment jig of the present invention is characterized by sequentially performing the following steps: attaching the bracket to the lower leader; connecting the bracket and the work device with the lifting device; raising the work device to apply tension to the lifting device; and fastening or unfastening the upper and lower flanges together with a plurality of bolts while the flange surfaces of the lower end of the leader and the upper end of the lower leader are pressed against each other. [Effects of the Invention]

[0010] According to the present invention, the lower leader attachment / detachment jig for a pile driver comprises a bracket detachably attached to the lower leader and a lifting device that connects the bracket to the work device, allowing the lower leader to follow the vertical lifting and lowering movement of the work device. Therefore, when applying tension to the lifting device, the work device (e.g., an auger) provided on the pile driver can be used, resulting in a simple lower leader attachment / detachment jig and method of use that do not require external power such as a crane or hydraulic jack.

[0011] Furthermore, since the bracket having a suspension attachment portion holds the lower leader in a suspended position with its upper flange surface facing the lower flange surface of the leader while tension is applied to the suspension, the interaction with the movement of the work device along the vertical direction not only facilitates flange alignment when attaching the lower leader, but also makes it easy to create a stable state for the lower leader when releasing the flange fastening and removing it, thus contributing to improved work efficiency, work accuracy, and safety.

[0012] Furthermore, since it is equipped with a tension indicator to monitor the magnitude of the tension applied to the lifting device, the magnitude of the tension applied to the lifting device can be monitored in a simple way by placing a commercially available tension indicator (for example, a spring scale) between the lifting device and its mounting part and reading the displayed value (scale). This helps prevent damage to the jig due to overload and also contributes to miniaturization and weight reduction of each component of the jig, such as the lifting device and bracket.

[0013] Furthermore, the suspension mounting section includes a shaft to which the suspension device is attached and a shaft support structure that movably supports the shaft. The shaft support structure includes a plate with a through hole through which the shaft passes and an expandable / contractable spring that elastically prevents the shaft from coming out of the through hole. This makes it possible to apply tension to the suspension device while visually checking the amount of spring compression, and to easily and appropriately obtain the tension of the suspension device necessary to press against the flange surface in order to create a flange contact state.

[0014] Furthermore, the warning indicator provided on the suspension mounting section is an indicator (e.g., a marking) provided on the circumferential surface of the shaft, and since this indicator appears and disappears on the plate surface in accordance with the relative movement between the shaft and the plate, it becomes easy to determine at a glance whether or not the jig is in an overloaded state. In other words, it helps prevent damage to the jig and, combined with visual confirmation of the spring's compression, can create a stable flange contact state. [Brief explanation of the drawing]

[0015] [Figure 1] This is a side view of a pile driver to which a lower leader attachment / detachment jig, which illustrates one embodiment of the present invention, is applied. [Figure 2] This is also a side view of the main part. [Figure 3] This is also a front view of the main section. [Figure 4] This is also a diagram illustrating the operation of the suspension fitting attachment section. [Figure 5] This is also a perspective view of the lower leader attachment / detachment jig. [Figure 6] This is also a perspective view from the stand. [Figure 7] This diagram shows the lower leader removal procedure, with the bracket attached to the lower leader connected to the auger by a suspension device. [Figure 8] This figure also shows the lower leader removal procedure, with the auger raised and tension applied to the lifting device. [Figure 9]It is a diagram showing the appropriate range of the spring contraction amount of the bracket, also in the procedure for removing the lower leader. [Figure 10] It is a diagram showing a state where the stand is installed on the ground, also in the procedure for removing the lower leader. [Figure 11] It is a diagram showing a state where the positions of the lower leader and the stand are aligned, also in the procedure for removing the lower leader. [Figure 12] It is a XII-XII cross-sectional view of FIG. 11. [Figure 13] It is a diagram showing a state where, also in the procedure for removing the lower leader, the lower leader whose flange fastening with the lower end flange surface of the leader has been released is inserted into the stand following the downward movement of the auger. [Figure 14] It is a diagram showing a state where the lower leader and the stand are fixed with a fixing pin, also in the procedure for removing the lower leader. [Figure 15] It is a diagram showing a state where, also in the procedure for removing the lower leader, the sling is rehung from the auger to the crane hook and the lower leader and the stand are lifted integrally. [Figure 16] It is a diagram showing a state where the positions of the basic leader and the lower leader are aligned in the procedure for attaching the lower leader. [Figure 17] It is a diagram showing a state where the space between the bracket and the auger is connected by a sling, also in the procedure for attaching the lower leader. [Figure 18] It is a diagram showing a state where the fixing pin between the lower leader and the stand is pulled out, also in the procedure for attaching the lower leader. [Figure 19] It is a diagram showing a state where, also in the procedure for attaching the lower leader, the auger is lifted to apply tension to the sling, and the lower leader is flange-fastened to the lower end flange surface of the basic leader. MODE FOR CARRYING OUT THE INVENTION

[0016] Figures 1 to 19 show an example of a pile driver to which the lower leader attachment / detachment jig of the present invention can be applied. The pile driver shown in this example is a pile driver 11 that employs a rack and pinion system as the lifting method for the working device, and as shown in Figure 1, comprises a lower traveling body 12, an upper rotating body 13 that is rotatably mounted on the upper part of the lower traveling body 12, a leader support 14 that is rotatably mounted on the front of the upper rotating body 13, a leader 15 that is rotatably mounted on the leader support 14, and a back stay (hydraulic cylinder) 16 that supports the leader 15 from the rear. Working devices such as an auger 17 that imparts rotation to the construction member (steel pipe pile, rod, etc.) and a lower guide 18 that holds the construction member are provided to move up and down along the leader 15.

[0017] The leader 15 that guides the working devices 17 and 18 up and down is made up of multiple leader members connected together, each having a rectangular tubular cross-section. It comprises a basic leader 19 attached to the leader support 14, multiple upper leaders (not shown) connected to the upper part of the basic leader 19, and a lower leader 20 connected to the lower part of the basic leader 19. As shown in Figure 9, each leader 19 and 20 is detachably connected by butting their flanges 19a and 20a together and fastening them with multiple bolts and nuts 21.

[0018] On both front ends of the leader 15, there is a pair of left and right guide rails 22, 22 that slidably engage with the guide gibs 17a, 18a of the working devices 17, 18. In addition, a rack 23 that meshes with the lifting pinions provided on the working devices 17, 18 is provided along the entire length of the leader 15 in the center of the front surface. As can be seen in Figures 2 and 5, the guide rails 22, 22 have a roughly square cross-sectional shape with chamfered outer corners, and their upper and lower ends align with the flange surfaces of the respective leaders 19, 20. The forward, backward, left, and right positions of the flanges 19a, 20a (bolt holes) are determined by inserting the downwardly protruding pins 22a, 22a into the pin holes 22b, 22b on the other side.

[0019] Incidentally, the pile driver 11 can perform two types of work, ground improvement and steel pipe installation, with a single unit. However, when switching between these types of work, if it becomes necessary to attach or detach the lower leader 20 due to a change in construction components, the lower leader attachment / detachment jig 31, which has the structure shown in Figures 2 to 6, is used.

[0020] The lower leader attachment / detachment jig 31 comprises a bracket 32 ​​detachably attached to the lower leader 20, and a pair of left and right lifting devices (e.g., lifting ropes) 33, 33 that connect the bracket 32 ​​to the work devices 17, 18, allowing the lower leader 20 to follow the vertical lifting and lowering movements of the work devices 17, 18. In addition, a shackle (connecting fitting) 34 attached to the lifting device 33 and a stand 35 for supporting the detached lower leader 20 in an upright position are used, and these can be included as components of the jig 31. In the following description, an auger 17 will be used as an example of a work device to which the lifting device 33 is attached, but similar functions and effects can be obtained with a lower guide 18.

[0021] The bracket 32 ​​is basically symmetrical in shape and has a main body that is roughly U-shaped in plan view, formed by connecting two opposing plate bodies 36, 36 with two pipe members 37, 37, and a pair of left and right suspension attachment parts 38, 38 provided on the outside of the plate bodies 36, 36. The plate body 36 is provided with a pin insertion part 36a for inserting the mounting pin 39 of the bracket 32, and a backing plate 36b that can abut against the front surface of the guide rail 22 is fixed to the inner surface of the plate body.

[0022] When setting the lower leader attachment jig 31 onto the leader 15, although the diagram is omitted, one end of the lifting devices 33, 33 is attached to the bracket 32 ​​placed on the ground, and the auger 17 is lowered to near the ground by operating the pile driver 11. Then, the other end of the lifting device 33 is attached to the lifting piece 40 provided at the lower end of the guide gib 17a (Figure 2), thereby connecting the auger 17 and the bracket 32 ​​via the two lifting devices 33, 33.

[0023] When the auger 17 is raised in this connected state, the bracket 32 ​​is lifted in accordance with the movement of the auger 17, and the guide rails 22, 22 of the lower leader 20 are positioned between the plates 36, 36. Then, by pressing the backing plates 36b, 36b against the front of the guide rails 22, 22, the position of the bracket 32 ​​in the front, back, left, and right directions relative to the lower leader 20 is determined. To determine the position in the vertical direction, the uppermost of the multiple upper and lower pin holes (also used for attaching other attachments) 22c provided on the outer surface of the guide rail 22 is used, and the upper end of the plate 36 is aligned with the upper surface of the flange 20a of the lower leader 20, allowing the mounting pins 39, 39 to be inserted and removed from both the left and right sides.

[0024] The suspension attachment section 38 forms suspension points (two locations, left and right) while balancing the lower leader 20. As shown in Figure 4, it comprises a shaft 41 to which the suspension device 33 is attached, a shaft support structure 42 for movably supporting the shaft 41, and a warning display section 43 provided on the circumferential surface of the shaft 41. With the bracket 32 ​​attached to the lower leader 20, the attachment section 38 is positioned considering both the position of the suspension piece 40 and the center of gravity of the lower leader 20. That is, as shown in Figure 2, the suspension attachment section 38 is positioned directly below the suspension piece 40 and on the vertical line connecting the center of gravity P of the lower leader 20 and the suspension piece 40 in a side view.

[0025] As a result, the bracket 32, while tension is applied to the suspension device 33, restricts the rotation of the lower leader 20 around the mounting pin 39 with the stopper function of the backing plate 36b, and holds the lower leader 20 in a suspended position with its upper flange surface (upper surface of flange 20a) facing the lower flange surface (lower surface of flange 19a) of the basic leader 19. Therefore, after the bolts and nuts 21 are removed and the flange fastening is released, the lower leader 20 remains suspended until it is received by the stand 35, but no movement of the center of gravity (swaying) occurs in the front, back, left, or right directions, and its posture is maintained while ensuring verticality.

[0026] The shaft support structure 42 comprises a plate 44 with a through hole through which the shaft 41 passes vertically, an expandable and contractible spring (compression spring) 45 positioned below the plate 44 so as to insert the shaft 41, and a spring mounting seat 46 locked to the shaft 41. The necessary strength is ensured by integrally providing a reinforcing member 42a that is connected to the lower side end of the plate 44 extending outward from near the upper end of the outer surface of the plate body 36 and is erected vertically on the outer surface of the plate body 36, and a guard member 42b which is a U-shaped member in side view with both upper ends bent at a right angle and both ends joined to the plate body 36, and is positioned to protect the outer surface of the spring 45. The shaft 41 is prevented from coming out downward from the through hole by locking its head 41a, which has a larger diameter than the diameter of the through hole provided in the plate 44, onto the plate 44.

[0027] The spring 45 is installed at its natural length between the plate 44 and the spring mounting seat 46, and is adjusted without any gap in the vertical direction by the locking nut (double nut) 42c of the spring mounting seat 46. As a result, when there is no tension applied to the suspension device 33 and no load is present, vertical play of the shaft 41 is suppressed, while when there is tension applied to the suspension device 33 and a load is present, the upward movement of the shaft 41 that would otherwise try to escape is elastically prevented by the repulsive force of the spring 45. In other words, when the shaft 41 rises due to the tension applied by the suspension device 33, the spring mounting seat 46 attached to the lower end compresses the spring 45, and the compressed spring generates a repulsive force proportional to the amount of compression. The head 41a of the shaft 41 rises from the plate 44 by the length at which the resulting repulsive force and tension balance each other.

[0028] The warning indicator 43 is a display that indicates when the tension applied to the suspension device 33 exceeds a set value. Specifically, it is an indicator that appears and disappears on the surface of the plate 44 in accordance with the relative movement between the shaft 41 and the plate 44. The indicator 43 can be any easily visible display, such as a marking painted red. The set value is set to a value that ensures the safety of the suspension device 33 against the increase in tension, and is based on the proportional relationship between the compression of the spring 45 and the tension, for example, it corresponds to a state where the compression of the spring 45 is 15 mm.

[0029] To explain this warning display in detail using Figure 4, the indicator 43 is positioned so that it is submerged on the plate surface of the plate 44 during the range from the no-load state in Figure 4(a) to the appropriate load limit state in Figure 4(b) of the load state of the lower leader attachment / detachment jig 31. The appropriate load limit state is when the amount of compression (shaft movement) L of the spring 45 is, for example, 15 mm, as shown in Figure 4(b). If the amount of compression L of the spring 45 increases beyond 15 mm, the jig 31 is considered overloaded, and the area of ​​the indicator 43, which appears on the plate 44 as a warning display, increases. When the amount of compression L of the spring 45 reaches 35 mm, the indicator 43 is fully extended on the plate 44, as shown in Figure 4(c). By warning the operator of such overload conditions with the display of the indicator 43, it is possible to quickly inform them of the condition in which it is necessary to stop the auger 17 from rising.

[0030] Here, the warning display unit 43 is a means for monitoring the increase in tension of the suspension device 33, but in operation, a suspension scale can be used together with the warning display unit 43, or as an alternative tension display unit. A suspension scale is a well-known tension measuring instrument that is interposed between the suspension device 33 and the suspension device mounting part 38, and can be configured to measure tension mechanically, such as a spring scale, or to measure tension electronically, such as a load cell.

[0031] As shown in Figure 6, the stand 35 has a symmetrical shape consisting of a base plate 47 on which the lower leader 20 is placed, a pair of left and right side plates 48, 48 provided on both sides of the base plate 47, and a front plate 49 provided between the side plates 48, 48 on the front side of the base plate 47. Multiple openings 47a, 48a and notches 47b, 49a are provided to reduce the overall weight. The side plates 48 are provided with pin insertion parts 48b for inserting the fixing pins 50 of the lower leader 20, and vertical plates 51, 51 are fixed to the lower part of the inner plate surface, as shown in Figure 12, between them and the front plate 49 to sandwich the guide rail 22 in the front-rear direction.

[0032] When setting the lower leader 20 on the stand 35, as will be described in detail later, the lower leader 20, which is suspended with the bolt fastening of the flange 20a released, is lowered to the stand 35 installed on the ground, following the downward movement of the auger 17, and the lower leader 20 is placed on the base plate 47. When the lower leader 20 is housed in the fixed position on the stand 35, the pin insertion portion 48b of the stand 35 and the pin hole 22c provided on the outer surface of the guide rail 22 align with each other (Figure 2), and as shown in Figure 14, the fixing pins 50, 50 can be inserted and removed from both the left and right sides.

[0033] When removing the lower leader 20 from the basic leader 19 using the lower leader attachment / detachment jig 31 configured in this way, as shown in Figure 7, the leader 15 of the pile driver 11 is positioned vertically, the working devices 17 and 18 are moved to appropriate positions below the basic leader 19, the bracket 32 ​​is attached to the lower leader 20, and the bracket 32 ​​and the auger 17 are connected by two lifting devices 33, 33. Then, as shown in Figure 8, the auger 17 is raised to apply tension to the lifting devices 33, 33.

[0034] The tension of the suspension device 33 is visually confirmed by the spring compression of the bracket 32 ​​and adjusted to a compression range of L = 5 to 10 mm, as shown in Figure 9. Here, a spring compression (L) of 5 mm corresponds to the downward load received from the lower leader 20 in a suspended state. Therefore, when the spring 45 is compressed by 5 mm or more, an upward pushing force is generated that resists the downward load of the lower leader 20, and as a result, a pressing force from the upper surface of the flange 20a of the lower leader 20 acts on the lower surface of the flange 19a of the basic leader 19. Note that if the tension of the suspension device 33 becomes excessive, it will result in an overload condition (Figure 4(c)). If the indicator 43 is displayed, the auger 17 is lowered to adjust the spring compression L of 45 to an appropriate range of 10 mm or less.

[0035] Next, as shown in Figure 10, with the stand 35 installed on the ground in front of the pile driver 11, the pile driver 11 is moved forward, and as shown in Figures 11 and 12, the front surface of the lower leader 20 and the front plate 49 of the stand 35 are brought into contact with each other to align their positions in the front, back, left, and right directions. Then, with the flange surfaces of the lower end of the basic leader 19 and the upper end of the lower leader 20 pressed against each other, the bolts and nuts 21 are removed to release the fastening between the upper and lower flanges 19a and 20a. In this case, even after the flange fastening is released, the upward force of the lower leader 20 acts on the basic leader 19, and the flange surfaces of both are maintained in close contact.

[0036] Next, as shown in Figure 13, the lower leader 20 is inserted into the stand 35, following the downward movement of the auger 17 along the vertical direction. When the lower leader 20 is placed on the base plate 47 of the stand 35, the guide rails 22, 22 are retracted into their fixed positions. In this state, as shown in Figure 14, the lower leader 20 and the stand 35 are secured with fixing pins 50, 50 at two locations on each side. After removing the lifting devices 33, 33 from the auger 17 and releasing the connection with the bracket 32, the pile driver 11 is moved backward, thereby securing the space above the lower leader 20 as the working space necessary for rigging. Then, as shown in Figure 15, after the lifting devices 33, 33 are transferred from the auger 17 to the crane hook 52, the lower leader 20 and the stand 35 are lifted together (upright) and transported to the storage location. Through these procedures, the removal of the lower leader 20 is completed. Furthermore, the lower leader 20 is placed upright in the storage location, and even with the jig 31 attached, it does not get in the way during storage.

[0037] On the other hand, when attaching the lower leader 20, which is supported by the stand 35, to the basic leader 19, the procedure is basically the reverse of the removal procedure described above. First, the leader 15 of the pile driver 11 is positioned vertically, and as shown in Figure 16, the pile driver 11 is moved forward to align the positions of the basic leader 19 and the lower leader 20 in the front, back, left, and right directions. Precision is not required for this alignment, and some misalignment is acceptable. Then, as shown in Figure 17, the bracket 32 ​​and the auger 17 are connected using the lifting devices 33, 33.

[0038] Next, as shown in Figure 18, the fixing pins 50, 50 are removed by a predetermined operation to release the fixing between the lower leader 20 and the stand 35, and then the auger 17 is raised to apply tension to the lifting devices 33, 33. At this time, a shift in the center of gravity of the lower leader 20 may occur when the lower end of the lower leader 20 separates from the base plate 47 of the stand 35, but this is only a slight misalignment between the main leader 19 and the lower leader 20.

[0039] By correcting its position in this way, the lower leader 20 is held in a suspended position with tension applied to the suspension device 33, that is, in a suspended position with its upper flange surface (upper surface of flange 20a) facing the lower flange surface (lower surface of flange 19a) of the basic leader 19. In the suspended position, the pin 22a and pin hole 22b of the guide rail 22 are aligned on the same axis (vertical line), and the positions of flanges 19a and 20a (bolt holes) in the front-back and left-right directions are naturally determined. Thus, the lower leader 20, after being removed from the stand 35, remains suspended until it comes into contact with the basic leader 19, but no movement of the center of gravity (swaying) occurs in the front-back and left-right directions, and its position is maintained while ensuring verticality.

[0040] When the lower leader 20 is made to follow the upward movement of the auger 17 along the vertical direction, and the upper and lower guide rails 22, 22 are pin-connected to each other, and the upper and lower flanges 19a, 20a are brought together, a pressing force from the upper surface of the flange 20a of the lower leader 20 acts on the lower surface of the flange 19a of the basic leader 19. Note that if the tension of the lifting device 33 becomes excessive, it will result in an overload condition (Figure 4(c)). If the indicator 43 is displayed, the auger 17 is lowered and adjusted so that the compression amount L of the spring 45 is within the appropriate range of 10 mm or less.

[0041] Then, as shown in Figure 19, the lower end of the basic leader 19 and the upper end of the lower leader 20 are pressed against each other, and the flange surfaces are in contact, and the bolts and nuts 21 are attached to fasten the upper and lower flanges 19a and 20a together. Finally, after lowering the auger 17 to release the tension of the lifting device 33, in other words, after confirming that the spring 45 is in its natural length state (elastic return state), the mounting pins 39, 39 of the bracket 32 ​​are removed, and when the auger 17 is lowered in this state, the bracket 32 ​​is lowered to the ground following the movement of the auger 17. Then, after the lifting devices 33, 33 are transferred from the auger 17 to the crane hook 52, the bracket 32 ​​is lifted up in place and, for example, loaded onto a prepared transport platform together with the stand 35. Through this procedure, the installation of the lower leader 20 is completed.

[0042] Thus, according to the present invention, the lower leader attachment / detachment jig 31 of the pile driver 11 includes a bracket 32 ​​that is detachably attached to the lower leader 20, and a lifting device 33 that connects the bracket 32 ​​to the working devices 17 and 18, causing the lower leader 20 to follow the vertical lifting and lowering movement of the working devices 17 and 18. Therefore, when tension is applied to the lifting device 33, the working device (e.g., auger 17) provided on the pile driver 11 can be used, and a simple lower leader attachment / detachment jig 31 and its usage method that do not require external power such as a crane or hydraulic jack are achieved.

[0043] Furthermore, since the bracket 32, which has a suspension attachment portion 38, holds the lower leader 20 in a suspended position with its upper flange surface facing the lower flange surface of the leader 19 while tension is applied to the suspension device 33, the interaction with the movement of the work devices 17 and 18 along the vertical direction not only facilitates flange alignment when attaching the lower leader, but also makes it easy to create a stable state for the lower leader 20 when releasing the flange fastening and removing it, thus contributing to improved work efficiency, work accuracy, and safety.

[0044] Furthermore, in addition to the warning display unit, a tension indicator can be provided to monitor the magnitude of the tension applied to the lifting device 33. By interposing a commercially available tension indicator (e.g., a spring scale) between the lifting device 33 and its mounting part 38, the magnitude of the tension applied to the lifting device 33 can be monitored in a simple manner by simply reading the displayed numerical value (scale). This helps prevent damage to the jig 31 due to overload and contributes to miniaturization and weight reduction of each component of the jig 31, such as the lifting device 33 and bracket 32.

[0045] Furthermore, the suspension mounting section 38 includes a shaft 41 to which the suspension device 33 is attached, and a shaft support structure 42 that movably supports the shaft 41. The shaft support structure 42 includes a plate 44 with a through hole through which the shaft 41 passes, and an expandable and contractible spring 45 that elastically prevents the shaft 41 from coming out of the through hole. This makes it possible to apply tension to the suspension device 33 while visually checking the amount of contraction of the spring 45, and to easily and appropriately obtain the tension of the suspension device 33 necessary to press against the flange surface in order to create a flange contact state.

[0046] Furthermore, the warning indicator 43 provided on the suspension mounting section 38 is an indicator (e.g., a marking) 43 provided on the circumferential surface of the shaft 41, and the indicator 43 appears and disappears on the plate surface of the plate 44 in accordance with the relative movement between the shaft 41 and the plate 44, making it easy to determine at a glance whether or not the jig 31 is in an overloaded state. In other words, it helps prevent damage to the jig 31 and, in combination with visual confirmation of the compression amount of the spring 45, can create a stable flange contact state.

[0047] It should be noted that the present invention is not limited to the above-described embodiments. The shape of the bracket constituting the lower leader attachment / detachment jig can be appropriately changed according to the specifications of the work device and leader, and wire ropes, chain ropes, etc., can be used for the lifting device. Furthermore, the means for monitoring the tension of the lifting device are arbitrary, and in addition to visually confirmable indicators such as tension display units and warning display units, configurations that emit sound or light can be considered if they attract the attention of the worker. Moreover, the shape of the stand is also arbitrary and can be appropriately set considering the work environment in which the lower leader attachment / detachment work is performed. [Explanation of Symbols]

[0048] 11...Pile driver, 12...Lower traveling body, 13...Upper rotating body, 14...Leader support, 15...Leader, 16...Backstay, 17...Auger (working device), 17a...Guide gib, 18...Lower guide (working device), 18a...Guide gib, 19...Basic leader, 19a...Flange, 20...Lower leader, 20a...Flange, 21...Bolts and nuts, 22...Guide rail, 22a...Pin, 22b...Pin hole, 22c...Pin hole, 23...Rack, 31...Lower leader attachment / detachment jig, 32...Bracket, 33...Lifting device, 34...Shackle, 35...Stand, 36...Plate body, 36a...Pin insertion section, 36b...Backing plate, 37...Pipe material, 38...Hanging device mounting section, 39...Mounting pin, 40...Hanging piece, 41...Shaft, 41a...Head, 42...Shaft support structure, 42a...Reinforcement, 42b...Guard, 42c...Locking nut, 43...Indicator (warning display section), 44...Plate, 45...Spring, 46...Spring mounting seat, 47...Base plate, 47a...Opening shape, 47b...Notch shape, 48...Side plate, 48a...Opening shape, 48b...Pin insertion section, 49...Front plate, 49a...Notch shape, 50...Fixing pin, 51...Vertical plate, 52...Crane hook

Claims

1. A lower leader attachment / detachment jig for a pile driver, wherein the lower leader is detachably attached to the lower end flange surface of the leader that guides the work device up and down by flange fastening with multiple bolts, The system comprises a bracket detachably attached to the lower leader, and a lifting device that connects the bracket to the work device, causing the lower leader to follow the vertical movement of the work device. The lower leader attachment / detachment jig is characterized in that the bracket has a suspension mounting portion to which the suspension device is attached, and the lower leader is held in a suspended position with its upper end flange surface facing the lower end flange surface of the leader while tension is applied to the suspension device.

2. The suspension device is equipped with a tension display unit for monitoring the magnitude of the tension applied to it. The lower leader attachment / detachment jig according to claim 1, characterized in that the tension indicator is a suspension scale used interposed between the suspension device and the suspension device mounting portion.

3. The suspension mounting section comprises a shaft to which the suspension device is attached, a shaft support structure that movably supports the shaft, and a warning display section that indicates when the amount of tension applied to the suspension device exceeds a set value. The shaft support structure comprises a plate having a through hole through which the shaft passes, and an expandable and contractible spring that elastically prevents the shaft from coming out of the through hole. The lower leader attachment / detachment jig according to claim 1, characterized in that the warning display unit is an indicator provided on the circumferential surface of the shaft and appears and disappears on the plate surface of the plate in accordance with the relative movement between the shaft and the plate.

4. A method for using the lower leader attachment / detachment jig according to any one of claims 1 to 3, characterized in that the steps of attaching the bracket to the lower leader, connecting the bracket and the work device with the lifting device, raising the work device to apply tension to the lifting device, and fastening or unfastening the upper and lower flanges together with a plurality of bolts while the flange surfaces of the lower end of the leader and the upper end of the lower leader are pressed against each other.

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