Hang Da Ji

Abstract

To provide a pile driver capable of directly detecting a ground contact state with a simple structure and maintaining a balance of contact surface pressure.SOLUTION: A pile driver includes a lower traveling body provided with a crawler, an upper revolving body rotatably provided on an upper part of the lower traveling body, an operator's cab provided in the upper revolving body, and outrigger jacks 19 respectively provided on the front, rear, left, and right of the upper revolving body. The outrigger jack 19 includes an extendable jack cylinder 19a, a grounding plate 22 provided at the lower end of the jack cylinder 19a, a grounding float 23 provided so as to protrude from the lower surface of the grounding plate 22, and a switch 24 for detecting relative movement of the grounding float 23 with respect to the grounding plate 22. The grounding float 23 has a grounding area A1 narrower than a grounding area A2 of the grounding plate 22 and a weight capable of obtaining a grounding surface pressure equal to the grounding surface pressure of the crawler. The operator's cab is equipped with a grounding confirmation light that lights up based on the detection result of the switch.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a pile driver, and more particularly to a pile driver equipped with outrigger jacks that come into contact with the ground to stabilize the vehicle body position. [Background technology]

[0002] A pile driver is generally equipped with a crawler-type running body that is excellent in ensuring stability, and four outrigger jacks that prevent lateral shaking that occurs during construction and tilting forward and backward when pushing and pulling out piles. The outrigger jack is made of a hydraulic jack cylinder, and can be used not only by lightly touching the ground during construction, but also by lifting the vehicle body in narrow areas to change the direction of the running body and change the direction of the pile driver. Such outrigger jacks require delicate positioning operations to create an intermediate extension state before construction. Therefore, from the viewpoint of work efficiency, the pile driver is equipped with a hydraulic circuit that detects the pressure increase caused by touching the ground and automatically stops the extension of the outrigger jacks (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-203244 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in order to maximize the functionality of the pile driver, it is preferable to balance the ground contact pressure between the crawler and the outrigger jacks to equalize the load. However, ground conditions vary, and if the four outrigger jacks are grounded one after another, it is possible that the balance of ground contact pressures may be lost between the start and the completion of the ground contact state. In such cases, it is difficult to say that the detected hydraulic pressure accurately reflects the ground contact state of the outrigger jacks using the conventional hydraulic control method using a pressure switch.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a pile driver that has a simple structure and is capable of directly detecting the ground contact condition and maintaining a balance of the ground contact pressure. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the pile driver of the present invention is a pile driver comprising a lower running body equipped with a crawler, an upper rotating body rotatably mounted on the upper part of the lower running body, a driver's cab provided on the upper rotating body, and outrigger jacks respectively provided on the front, rear, left and right sides of the upper rotating body, wherein the outrigger jack comprises an extendable jack cylinder, a ground plate provided at the lower end of the jack cylinder, a ground float provided so as to protrude freely from the underside of the ground plate, and a switch for detecting the relative movement of the ground float with respect to the ground plate, the ground float having a contact area narrower than the contact area of ​​the ground plate and a mass capable of obtaining a ground pressure equal to the ground pressure of the crawler, and the driver's cab is provided with a ground confirmation light which turns on based on the detection result of the switch.

[0007] The ground float has a float body placed on the upper surface of the ground plate and a ground protrusion protruding from the lower surface of the float body and inserted into a through hole provided in the ground plate, and the center of gravity of the float body is located on an extension of the through hole. Furthermore, the ground plate is detachably provided at the lower end of the jack cylinder. Effect of the Invention

[0008] According to the pile driver of the present invention, the grounding float, which is provided to protrude freely from the underside of the ground plate, has a grounding area smaller than the grounding area of ​​the ground plate and a mass capable of obtaining a grounding pressure equal to that of the crawler, so that the grounding float itself can be made small and lightweight, and can be raised during the grounding operation at the optimum time when the grounding pressures of the crawler and outrigger jack are balanced. This makes it possible to turn on the grounding confirmation light with a simple circuit configuration that only requires the incorporation of a detection switch, and the operator can reliably and appropriately ground the outrigger jack by himself. [Brief description of the drawings]

[0009] [Figure 1] 1 is a side view of a pile driver showing one embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] FIG. 11 is an explanatory diagram of the operation of the detection switch. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1 to 4 show an example of the present invention applied to a small pile driver. As shown in FIG. 1, the pile driver 11 has an upper rotating body 14 rotatably mounted on the upper part of a lower traveling body 13 equipped with a crawler 12, and a pile driving device such as a leader 15 and an auger (rotary drive device) 16 that moves up and down along the front of the leader 15 is mounted in the center of the front part of the upper rotating body 14. In addition, a driver's cab 17 is mounted on the right side of the frame of the upper rotating body 14, and an engine room 18 that houses an engine and a hydraulic pump is mounted on the left side. Furthermore, outrigger jacks 19 for stabilization are provided at four points on the front, rear, left and right of the upper rotating body 14, and a counterweight 20 for balancing the machine body is mounted on the rear end of the upper rotating body 14.

[0011] When the pile driver 11 is used for the purpose of burying steel pipe piles, the operating means (switches, levers, etc.) in the driver's cab 17 is operated to extend the four outrigger jacks 19 and ground them all, and with the leader 15 in an upright pile driving position, a driving force is obtained from the auger 16 to rotate and press the steel pipe pile (not shown) into the ground. In such pile driving work, a composite load of axial (vertical) tension and torsion is applied to the leader 15 by the propulsive force of the rotating pile, and this load is transmitted through the main frame and acts on the track frame 21 to which the left and right crawlers 12 are attached, and on each of the outrigger jacks 19.

[0012] The ground contact state of the outrigger jack 19 is created by hydraulically extending the jack cylinder, but if the tension on the ground is too strong, the ground contact pressure of the crawler 12 is reduced, while if the tension is too weak, the machine cannot fully perform its supporting function. Therefore, in order to maximize the pile driving function, it is necessary to balance the ground contact pressures of the crawler 12 and the outrigger jack 19 in advance. However, the operation of the outrigger jack 19 requires delicate operation to stop it at an intermediate extension position, and even if an observer is present during operation, it is difficult to determine whether appropriate ground contact pressure is obtained when the machine is in the ground contact state.

[0013] Therefore, the pile driver 11 is provided with a ground contact confirmation light to inform the operator of the ground contact state of the outrigger jack 19, and a detection mechanism for making this light function under optimal conditions.

[0014] The ground contact confirmation light is an indicator light (LED) that lights up based on the mechanical detection result that the outrigger jack 19 has reached a specified ground contact pressure; although not shown in the figure, four of them are provided in appropriate positions in the operator's cab 17, for example, corresponding to the arrangement of the operating switches for the outrigger jack 19.

[0015] As shown in Figures 2 to 4, the detection mechanism is arranged on the ground plate 22 of the outrigger jack 19, and mainly includes a ground float 23 that protrudes freely from the underside (ground surface) of the ground plate 22 and can be freely moved in and out, and a switch 24 that detects the relative movement of the ground float 23 in the vertical direction with respect to the ground plate 22.

[0016] The ground plate 22 is pivotally supported at the lower end of the jack cylinder 19a so as to be able to swing. In this embodiment, a large ground plate (jack plate) 22 that can be attached and detached as an attachment will be described as an example. This ground plate 22 has a plurality of mounting members 22a that also serve as a positioning function on the upper surface of a thick circular plate, and after sliding-mounting it from the side onto the lower surface of a smaller standard ground plate 19b, a pin-shaped fixing device 25 is used to prevent it from falling off the jack cylinder 19a. In addition, the peripheral portion of the ground plate 22 is provided with a circular through hole 22b that matches the arrangement of the ground float 23, and a pair of hanging ears 22c, 22c for attaching a hanging tool for transportation.

[0017] As shown in Fig. 4 and other figures, the ground float 23 has a rectangular parallelepiped float body 23a placed on the upper surface of the ground plate 22, and a cylindrical ground protrusion 23b that protrudes directly downward from the center of the underside of the float body 23a and is inserted into a through hole 22b in the ground plate 22. As can be seen from Fig. 3, the ground float 23 placed on such a ground plate 22 has a ground contact area A1 of the ground protrusion 23b that is significantly smaller than the ground contact area A2 of the ground plate 22, for example, A1 is 1 / 40 of A2. This means that the load acting on A1 to obtain the same ground contact pressure will be 1 / 40 of the load acting on A2.

[0018] The float body 23a has a weight function for obtaining the grounding surface pressure of the grounding float 23, and in the placed state where the grounding protrusion 23b which is integral with the float body 23a is inserted and engaged in the through hole 22b, its center of gravity is located on the extension (axis) of the through hole 22b. The grounding protrusion 23b is formed to be longer than the thickness of the grounding plate 22, but the maximum amount of protrusion from the lower surface of the grounding plate 22 is set small, for example, to about 5 mm, taking into consideration the movable range of the grounding float 23 accompanying the rising and receding movements.

[0019] The operation of the grounding float 23 will be described below with reference to Figure 4. When the outrigger jack 19, which is in a fully contracted state, is extended, the grounding protrusion 23b of the grounding float 23 comes into contact with the ground G before the grounding plate 22, as shown in Figure 4(a). However, because the surface layer of the ground G is relatively soft, in the light contact state, the entire weight of the grounding float 23 is still resting on the grounding plate 22, and no grounding surface pressure is generated for the grounding float 23.

[0020] Then, when the ground G is compacted by the downward moving ground plate 22 and the ground float 23, as shown in Fig. 4(b), the ground projection 23b sinks into the through hole 22b of the ground plate 22 due to the repulsive force of the ground G, and the float body 23a rises above the upper surface of the ground plate 22. As a result, the ground float 23 generates a contact surface pressure per unit contact area obtained by dividing its weight (load) by the contact area A1.

[0021] Here, the mass of the ground float 23 is set to a weight capable of obtaining a ground pressure equal to that of the crawler 12, for the purpose of balancing the ground pressures of the crawler 12 and the outrigger jack 19. The ground pressure of the crawler 12 is the ground pressure per unit ground area obtained by dividing the total installed weight (load) of the pile driver 11 by the ground areas of the left and right crawlers 12. In this case, the ground area of ​​the crawler 12 corresponds to the area of ​​a rectangle in a plan view roughly defined by the track width and the wheelbase (the axis distance between the driving wheels and the driven wheels).

[0022] As an example, the ground pressure of the crawler 12 is set to 75 kPa (760 gf / cm 2 ), the grounding area A1 of the ground float 23 is 0.7854 cm 2 (equivalent to a diameter of 10 mm), the required mass of the ground float 23 is 760 (gf / cm 2 )×0.7854(cm 2 )=596.9g. In other words, if a steel ground float 23 is used, the outer dimensions (height x width x thickness) of the float body 23a need only be about 5 cm x 5 cm x 3 cm.

[0023] The contact surface pressure of the grounding float 23 thus obtained rises to a maximum in the short time it takes from the light contact state (FIG. 4(a)) to the state where the float body 23a floats up (FIG. 4(b)). In other words, at the timing when the float body 23a floats up, the contact surface pressure of the grounding plate 22 becomes equal to the contact surface pressure generated on the crawler 12 and is in a balanced state.

[0024] The switch 24 incorporated in the detection mechanism and the operation support function of the pile driver 11 for turning on the ground contact confirmation light based on the detection result will be described below with reference to Figs. 2 to 4.

[0025] The switch 24 is a limit switch connected by wire to the electrical circuit of the ground confirmation light, and transmits external forces and movements acting on the push-plunger-shaped actuator 24a to the built-in switch. The switch 24 is attached to the top plate 26a of the case 26 that houses the ground float 23, with the downward actuator 24a protruding into the case 26. The actuator 24a is located vertically above (directly above) the ground protrusion 23b, and moves upward when the top surface of the float body 23a abuts against it, closing (ON) the circuit contact. This switches the ground confirmation light between on (ON) and off (OFF) based on the relative vertical movement between the ground float 23 and the ground plate 22.

[0026] When the pile driver 11 thus constructed is used to drive piles, the ground plate 22 is attached to each of the four outrigger jacks 19 in advance, the lower traveling body 13 is driven to adjust the position and direction of the pile driver 11, and the outrigger jacks 19 are then grounded one by one. At this time, when the ground G is compacted by the downwardly moving ground plate 22 and ground float 23, the ground surface pressure starts to rise. Then, at the timing when the float body 23a rises from the upper surface of the ground plate 22 as shown in FIG. 4(b), a ground surface pressure equal to the ground surface pressure of the crawler 12 is generated on the ground plate 22.

[0027] When the upward movement of the grounding float 23 closes the contacts of the switch 24 and the corresponding grounding confirmation light turns on, the driver, having grasped the grounding situation, can perform an operation to stop the outrigger jacks 19, for example, by returning the operation switch to neutral. When all the outrigger jacks 19 are grounded in this way, the mutual grounding surface pressures of the crawler 12 and the outrigger jacks 19 on the front, rear, left and right sides are equally balanced, enabling the pile driving function to be performed effectively.

[0028] However, when a work load is applied when driving in or pulling out a pile, the ground contact pressure of the outrigger jack 19 increases or decreases according to the load, and it is possible that the ground contact confirmation light in the area where the load has decreased will go out. In such a situation, if the light comes back on (restores), the driver can determine that it is OK to continue driving. On the other hand, if the light remains out even after the load is removed, the driver can determine that it is OK to temporarily suspend driving and re-ground the outrigger jack 19 in the area in question. In other words, it becomes possible to grasp the ground contact situation and make appropriate decisions about measures to be taken in response.

[0029] Thus, according to the pile driver 11 of the present invention, the grounding float 23 provided to protrude freely from the underside of the grounding plate 22 has a grounding area A1 smaller than the grounding area A2 of the grounding plate 22 and a mass capable of obtaining a grounding pressure equal to that of the crawler 12, so that the grounding float 23 itself can be made small and lightweight, and can be raised during the grounding operation at the optimum time when the grounding pressures of the crawler 12 and the outrigger jack 19 are balanced. This makes it possible to turn on the grounding confirmation light with a simple circuit configuration that merely incorporates the detection switch 24, and the operator can reliably and appropriately ground the outrigger jack 19 by himself.

[0030] In addition, the grounding float 23 is integrally provided with a float body 23a which carries the weight and a grounding protrusion 23b which is inserted into the through hole 22b of the grounding plate 22, and the center of gravity of the float body 23a is positioned on the extension of the through hole 22b, so that the relative movement (up and down movement) of the grounding float 23 with respect to the grounding plate 22 can be performed smoothly, which contributes to improving the detection accuracy of the switch 24.

[0031] Furthermore, since the ground plate 22 is detachably provided at the lower end of the jack cylinder 19a, it can be attached to an existing pile driver 11 after the fact, and the attachment method can be achieved by a simple slide attachment (pin fixing) that does not require a special tool. In particular, by attaching the ground plate 22 that is one size larger than the standard ground plate 19b as in the embodiment, it is possible to effectively prevent subsidence due to the grounding operation or work load, which is excellent in maintaining the balance of the ground surface pressure.

[0032] The present invention is not limited to the above-mentioned embodiment, and the mechanism for detecting the ground pressure may be provided not only on a large ground plate but also on a standard-sized ground plate, and the shape, size, and arrangement of the ground float may be appropriately changed according to the specifications of the pile driver. Furthermore, if the detection result is used as a signal to stop the operation of the outrigger jack, more stable operation can be performed, and if the detection switch is a wireless type, there is no need to worry about disconnection, so the pile driver can be widely applied to the environment in which it is used. [Explanation of symbols]

[0033] 11...pile driver, 12...crawler, 13...lower running body, 14...upper rotating body, 15...leader, 16...auger, 17...operator cab, 18...engine room, 19...outrigger jack, 19a...jack cylinder, 19b...standard ground plate, 20...counterweight, 21...truck frame, 22...ground plate, 22a...mounting member, 22b...through hole, 22c...hanging ear, 23...ground float, 23a...float body, 23b...ground protrusion, 24...switch, 24a...operating part, 25...fixing device, 26...case, 26a...upper plate

Claims

1. A pile driver including a lower traveling body equipped with a crawler, an upper rotating body rotatably provided on an upper portion of the lower traveling body, a driver's cab provided on the upper rotating body, and outrigger jacks provided on the front, rear, left and right sides of the upper rotating body, The outrigger jack includes an extendable jack cylinder, a ground plate provided at the lower end of the jack cylinder, a ground float provided so as to protrude and retract from the lower surface of the ground plate, and a switch for detecting the relative movement of the ground float with respect to the ground plate, the ground float has a contact area smaller than the contact area of ​​the ground plate and a mass capable of obtaining a contact pressure equal to the contact pressure of the crawler, A pile driver characterized in that the operator's cab is provided with a grounding confirmation light that turns on based on the detection result of the switch.

2. The ground float has a float body placed on the upper surface of the ground plate, and a ground protrusion protruding from the lower surface of the float body and inserted into a through hole provided in the ground plate, 2. The pile driver according to claim 1, wherein the center of gravity of the float body is located on an extension of the through hole.

3. 3. The pile driver according to claim 1, wherein the ground plate is detachably provided at a lower end of the jack cylinder.

Images