JP7463766B2 - Lifting device and reinforcing cage installation method - Google Patents

Description

The present invention relates to a lifting device used when lifting a load with a lifting machine, and a method for erecting a reinforcing bar cage using this lifting device.

Conventionally, the reinforcing bars that make up the reinforced concrete walls and cast-in-place piles that are installed underground are assembled on the ground, then suspended by a crane or other lifting machine via wires and lowered into an excavated trench or underground hole to be erected.

For example, Patent Document 1 discloses a method for erecting a reinforcing bar cage for use with cast-in-place piles. Specifically, a traverser (suspension jig) is hung from a crane hook via a wire, and a hoisting device is suspended from this traverser. A reinforcing ring is also provided near the top of the reinforcing bar cage. The hoisting device and the reinforcing ring on the reinforcing bar cage are then connected with a sling wire, and the reinforcing bar cage is lowered into the pile hole via a crane.

JP 2014-74304 A

According to Patent Document 1, even if the reinforcing bar cage is heavy, it can be stably suspended without deforming its shape. However, a suspension allowance is required between the crane hook and the reinforcing ring attached to the reinforcing bar cage, the combined length of the wire, traverser (suspension jig), suspension device, and sling wire.

Therefore, in construction environments with overhead restrictions, the overall length of the reinforcing cage must be shortened by the amount of the hanging allowance in order to ensure the above-mentioned hanging allowance. This means that when multiple reinforcing cages are connected in the height direction to ensure the required length, the number of reinforcing cages must be increased, which in turn increases the number of joints between the reinforcing cages. This leads to poor construction workability and an increase in the number of parts, which can be economically disadvantageous.

In addition, when using a sling wire to suspend a rebar cage, the cage must be balanced by adjusting the length of the sling wire using a motor block or chain block, making the work complicated.

Furthermore, when the reinforcing bar cage is long and large, it is necessary to erect the cage that has been stored in a lying-down position. However, if a sling wire is used for the erecting work, the sling wire is likely to become tangled between the crane hook and the reinforcing bar cage when the cage is changed from a lying-down position to an upright position, creating a safety issue during the erecting work.

The present invention was developed in consideration of these problems, and its main objective is to provide a lifting device that can easily perform lifting work for reinforcing bars with a simple configuration, and a method for erecting reinforcing bars using the lifting device.

In order to achieve this objective, the lifting device of the present invention comprises a load support bracket that is attached to a bar that passes through a reinforcing bar cage, and a connecting bracket that connects the load support bracket to a lifting bracket that is engaged with a crane hook , the lifting bracket being connected to the connecting bracket using a lifting bracket mounting hole provided in the connecting bracket, a pair of the load support brackets are connected to the connecting bracket in parallel with a gap between them, each of the load support brackets is provided with a through hole portion through which the bar passes, both through hole portions are positioned so that their central axes are parallel to the lifting bracket mounting hole, and the bar is movably attached to the load support bracket.

With the lifting device of the present invention, the bar bars on the reinforcing bar cage are attached to the load support fittings, a lifting fitting is connected to the connecting fitting, and the hook of a lifting machine or the like is engaged with this lifting fitting, so that the reinforcing bar cage can be lifted by the lifting machine. This makes it possible to significantly improve the workability of the lifting work compared to when a lifting scale and a sling wire are used.

In addition, a lifting device can be used to erect the reinforcing bar cage that has been stored in a lying-down position, making it easier and safer to erect the reinforcing bar cage than using a sling wire.

In this way, the entire lifting process from raising the reinforcing bar cage to suspending it can be simplified, making it possible to shorten the overall construction time.

In addition, by eliminating the need for a sling wire, there is no need for a motor block used to adjust the length of the sling wire, nor is there a need to secure a power source to operate these, making it possible to simplify the equipment required for lifting work.

Furthermore, the load support bracket can be attached to the bar bar provided on the reinforcing bar cage simply by passing the bar bar through the through hole. This allows the attachment position to be adjusted simply by moving the load support bracket appropriately along the bar bar, making it easy to adjust the position to align the suspension point with the center of gravity of the reinforcing bar cage.

The method of erecting a reinforcing bar cage of the present invention is a method of erecting a reinforcing bar cage in an underground excavation section using the lifting device of the present invention , which is characterized in that the reinforcing bar cage in a lying down position is placed on a raising device in a lying down position, the pin installed on the raising device is inserted into the through hole of the load support bracket that constitutes the lifting device, the crane hook is engaged with the hanging bracket provided on the connecting bracket, the reinforcing bar cage is erected together with the raising device, the load support bracket is attached to the bar that passes through the reinforcing bar cage in place of the pin, and the reinforcing bar cage is then lowered and erected into the underground excavation section by a lifting machine via the hanging bracket.

According to the method for erecting a reinforcing bar cage of the present invention, the reinforcing bar cage can be suspended by a hoist via the suspension fittings simply by attaching the load support fittings of the hoisting device to the bar that passes through the reinforcing bar cage. This eliminates the need for the complicated slinging work that was previously required to suspend the reinforcing bar cage, making it possible to significantly reduce the time required for erection work.

In addition, the required hanging allowance between the lifting machine and the reinforcing bar cage can be made shorter than when using a sling or sling wire, allowing the overall height of the reinforcing bar cage to be increased accordingly. Therefore, when the construction site has a low headroom and a structure corresponding to a large depth is to be constructed in the underground excavation section, the number of reinforcing bar cages connected in the depth direction can be reduced.

This will significantly reduce the time it takes to connect the reinforcing bars and will also reduce the number of parts needed to connect the reinforcing bars, contributing to shorter construction times and reduced construction costs.

According to the present invention, the load support bracket is attached to the bar on the reinforcing bar cage, and the hanging bracket connected to the load support bracket via the connecting bracket is hooked to the hook of a lifting machine or the like, making it possible to easily perform the lifting work of the reinforcing bar cage.

FIG. 2 is a diagram showing a state in which a lifting device according to an embodiment of the present invention is installed on a reinforcing bar cage. 3A and 3B are diagrams showing details of a suspension device according to an embodiment of the present invention. FIG. 1 is a diagram showing the procedure for erecting a reinforcing bar cage in an embodiment of the present invention (part 1). FIG. 2 is a diagram showing the procedure for erecting a reinforcing bar cage in an embodiment of the present invention (part 2). FIG. 1 is a diagram showing a lifting device provided on a lifting device in an embodiment of the present invention (part 1). FIG. 2 is a diagram showing a lifting device provided in a raising device in an embodiment of the present invention (part 2). 1 is a diagram showing a state in which a lifting device is attached to a reinforcing bar cage in an embodiment of the present invention. FIG. 11A and 11B are diagrams showing how the position of the lifting device is adjusted relative to the reinforcing bar cage in an embodiment of the present invention. 13A and 13B are diagrams illustrating another example of a suspension device according to an embodiment of the present invention.

The lifting device of the present invention can be used for any shape of load, but in this embodiment, we will use a reinforcing bar cage used when constructing a reinforced concrete wall underground as an example, and explain the details and the method of erecting the reinforcing bar cage using the lifting device with reference to Figures 1 to 9.

Before explaining the lifting device, we will explain the outline of the reinforcing bar cage on which the lifting device is mounted, with reference to the plan view in Figure 1(a) and the cross-sectional view in Figure 1(b).

As shown in Fig. 1(a) and (b), the reinforcing bar cage 1 is composed of a number of vertical bars 1a arranged in parallel at a predetermined interval, and a number of horizontal bars 1b that intersect the vertical bars 1a and are arranged in parallel at a predetermined interval. These horizontal bars 1b are arranged to surround the vertical bars 1a, so that the reinforcing bar cage 1 is formed into a roughly cylindrical rectangular parallelepiped that is closed in a plan view.

In addition, as shown in FIG. 1(b), a steel frame-shaped reinforcing member 2 is provided inside the reinforcing bar cage 1. The reinforcing member 2 is composed of an upper frame-shaped body 2a arranged near the top of the reinforcing bar cage 1, a lower frame-shaped body 2b arranged near the bottom, and a connecting member 2c that connects them. As shown in FIG. 1(a), both the upper frame-shaped body 2a and the lower frame-shaped body 2b are formed in a roughly cylindrical shape that circumscribes the reinforcing bar cage 1, and as shown in FIG. 7, they are installed on the reinforcing bar cage 1 via a connecting jig 2d such as a bundling jig.

In this embodiment, these reinforcing members 2 are made of strip-shaped steel plates, but any material may be used as long as it functions as a reinforcing material that maintains the shape of the reinforcing cage 1. Also, the connecting jig 2d that connects the reinforcing members 2 to the reinforcing cage 1 does not necessarily have to be provided, and any means that can connect the two may be used, such as welding, to fasten them together.

As shown in FIG. 4(c), the reinforcing bar cage 1 configured as described above is lowered by a crane 9 via a lifting device 4 into an excavation trench 10 created in the ground, and after it is erected, concrete is filled into the excavation trench 10 to form a reinforced concrete wall.

<<Lifting device>>
As shown in FIG. 2 , the lifting device 4 is composed of a connecting fitting 5 and a load support fitting 6 , and is installed on the reinforcing bar cage 1 via a bar 3 that passes through the reinforcing bar cage 1 .

As shown in FIG. 2, the connecting fitting 5 is a fitting that connects the load support fitting 6 (described later) to the hanging fitting 7 to which the crane hook 9a is attached, and has a pair of legs 51 spaced apart and a connecting part 52 that connects them.

The pair of legs 51 are arranged to hang down from the connecting portion 52, so that the connecting fitting 5 is formed in a roughly U-shape, but this is not limited to this and may be formed in a roughly H-shape, for example. A hanging fitting attachment hole 52a for attaching the hanging fitting 7 is provided approximately in the center of the connecting portion 52, and a hanging load support fitting 6 is provided on each of the pair of legs 51.

The load support bracket 6 comprises a main body 61 and a pair of semicircular grooves 62 that are provided continuously on both ends of the main body 61. The main body 61 is made of a tubular member, and the semicircular grooves 62 are formed in a half-split structure with the upper half of the main body 61 cut out. The hollows of the main body 61 and the pair of semicircular grooves 62 are connected to form the through-holes 6a provided in the load support bracket 6.

The load support brackets 6 configured in this way are arranged in parallel in pairs, and the through-holes 6a of both brackets are arranged so that their central axes are parallel to the hanging bracket mounting holes 52a provided in the connecting portion 52.

The bar bars 3, which function as mounting rods to which the load support brackets 6 are attached, are arranged in pairs at a distance from each other on the lower side of the upper frame body 2a constituting the reinforcing member 2, penetrating the reinforcing bar cage 1 in the depth direction (width direction of the excavation trench 10), as shown in Figures 1(a) and (b).

The hoisting fixture 7 attached to the connecting fixture 5 may be any type that can be used to connect the crane hook 9a to a lifting machine or other member that can be engaged with the crane hook 9a. In this embodiment, a so-called shackle is used. Therefore, as shown in FIG. 2, the shackle pin 72 is inserted through the hoisting fixture attachment hole 52a of the connecting portion 52 that constitutes the connecting fixture 5, and through the through hole 71a of the shackle body 71 that is approximately U-shaped.

Then, the tip of the shackle pin 72 is fastened with a nut 73, so that the hanging fitting 7 can be attached to the connecting fitting 5. Note that the hanging fitting 7 is not necessarily limited to a shackle, and any commonly used hanging fitting 7, such as a master ring, can be used.

As shown in FIG. 1(a), the lifting device 4 of the above configuration is attached to the bar 3 by passing the bar 3, which is provided so as to penetrate near the longitudinal center of the reinforcing bar cage 1, through the through hole 6a of the load support bracket 6. In this state, the crane hook 9a is engaged with the hanging bracket 7 provided on the connecting bracket 5, and the reinforcing bar cage 1 is suspended from the crane 9 via the hanging bracket 7, the lifting device 4, and the bar 3.

This makes it possible to omit the lifting scale and sling wire that were previously placed between the rebar cage 1 and the crane hook 9a, eliminating the need for complicated slinging work and significantly improving the workability of lifting work.

In this embodiment, the bar 3 that passes through the reinforcing bar cage 1 is used as the mounting rod to which the load support bracket 6 is attached, and the lifting device 4 is installed on the reinforcing bar cage 1, but this is not necessarily limited to this, and for example, a part of the reinforcing bar cage 1 may be used as the mounting rod.

<<How to install the reinforcing bar cage>>
A series of procedures from the lifting device 4 used to lift the reinforcing bar cage 1 to the lifting by a crane and then lowering and setting it into the excavation trench 10 will be described with reference to Figures 3 to 8. In this embodiment, the lifting device 8 is used to lift the reinforcing bar cage 1 in a lying position, and the lifting device 4 is used for the work using the lifting device 8 as an example.

<<Rising device>>
As shown in Figure 3 (c), the raising device 8 comprises an L-shaped frame body 81 having a bottom frame 81a and a wall frame 81b, and a wheel section 82 provided near the protruding corner of the frame body 81 on the wall frame 81b side.

The bottom frame 81a is provided with legs 84 that support the frame body 81 substantially horizontally together with the wheel section 82 when the erection device 8 is in the erected position. As shown in FIG. 3(a), the wall frame 81b is provided with not only legs 84 that support the frame body 81 substantially horizontally together with the wheel section 82 when the erection device 8 is in the lying position, but also with a lifting device installation section 83 near the end that is at the top when in the erected position.

As shown in FIG. 3(a), the lifting device installation section 83 includes a pair of protruding members 831 that stand upright from the top surface of the wall frame 81b in the collapsed position, and, as shown in FIG. 5, a chain member 832 that is provided at the tip of each of the protruding members 831.

As shown in Figures 5 and 6, the chain member 832 is made up of two U-shaped rings 833 and 834 connected in a chain shape. The pin 833a of one of the U-shaped rings 833 is installed on the protruding member 831 via a bearing 831a, and the pin 834a of the other U-shaped ring 834 functions as a mounting rod to which the load support bracket 6 is attached.

As shown in Figures 3(b) and (c), the pin 833a of one U-shaped ring 833 is arranged to extend in a substantially horizontal direction regardless of the position of the wall frame 81b, and the pin 834a of the other U-shaped ring 834 is always perpendicular to the pin 833a of the other U-shaped ring 833, as shown in Figures 5 and 6.

In this state, the pin 834a of the other U-shaped ring 834 provided on the erection device 8 is passed through the through hole 6a of the load support bracket 6, whereby the load support bracket 6 is attached to the pin 834a of the other U-shaped ring 834, and the lifting device 4' is installed on the erection device 8.

<Reinforced concrete cage erection process>
First, near the excavation trench 10, the reinforcing bar cage 1 in a lying down position is erected by the erecting device 8 and the lifting device 4'.

As shown in FIG. 3(a), the reinforcing bar cage 1 transported to the construction site in a fallen position is placed on the top surface of the wall frame 81b of the erection device 8, which is also in a fallen position. To erect the reinforcing bar cage 1, the crane hook 9a is hooked to the hanging fitting 7 attached to the connecting fitting 5, and then the frame body 81 is lifted up by the crane 9.

As a result, as shown in Figures 3(b) and (c), the frame body 81 of the erecting device 8 changes its position from a lying down state to an upright state with the wheels 82 as the fulcrum, and the reinforcing bar cage 1 also assumes an upright position. In this way, when the lifting device 4' is used to erect the reinforcing bar cage 1 that has been stored in a lying down position, it becomes possible to erect the reinforcing bar cage 1 more easily and safely than when a sling wire is used.

<Installation process of the lifting device>
Next, as shown in Figure 4(a), the crane hook 9a is removed from the lifting device 4' provided on the raising device 8, and then, using this crane hook 9a, the lifting device 4 for suspending the reinforcing bar cage 1 is provided near the upper part of the reinforcing bar cage 1 in the upright state, as shown in Figure 4(b).

Specifically, after removing the crane hook 9a from the lifting device 4 attached to the erection device 8, as shown in FIG. 7, the removed crane hook 9a is engaged with the hoisting bracket 7 of the lifting device 4 used for lifting the reinforcing bar cage 1. In this way, the lifting device 4 is suspended near the position where the reinforcing bar cage 1 is arranged, and the two bar bars 3 are passed through the depth direction of the reinforcing bar cage 1 (width direction of the excavation trench) and through the through hole portion 6a of the lifting support bracket 6.

The load support bracket 6 is provided with a semicircular groove 62, so that the bar 3 can be smoothly inserted into the through hole 6a. In addition, by arranging the two bar 3 on the lower side of the upper frame 2a constituting the reinforcing member 2, the reinforcing cage 1 can be suspended via the reinforcing member 2, so that damage such as deformation of the reinforcing cage 1 can be prevented.

<Installation process of the lifting device>
After this, the position of the suspension point of the reinforcing bar cage 1 (the position of the hanging fitting 7 provided on the lifting device 4) is adjusted so that it is located on the center of gravity of the reinforcing bar cage 1, and then the erection work of the reinforcing bar cage 1 is carried out.

The diameter of the through hole 6a provided in the load support bracket 6 of the lifting device 4 is slightly larger than the diameter of the bar 3, and is configured to be able to move along the longitudinal direction of the bar 3. Therefore, the position of the lifting bracket 7, which serves as the suspension point, is adjusted by moving the lifting device 4 along the bar 3 in the longitudinal direction of the reinforcing bar cage 1, as shown in Figure 8.

At this time, each time the position is adjusted, the rebar cage 1 is lifted slightly using the crane 9 to check the balance of the lifted rebar cage 1. If the lifted rebar cage 1 tilts, the rebar cage 1 is lowered once and the lifting device 4 is moved in the longitudinal direction of the bar 3 to adjust the balance.

In this way, by using the lifting device 4, the position adjustment work to align the lifting point with the center of gravity of the reinforcing bar cage 1 can be easily performed while ensuring safety. In addition, not only is the length adjustment work of the lifting wire unnecessary as in the past, but it also eliminates the need for a motor block used to adjust the length of the lifting wire, and the need to secure a power source to operate these. Therefore, the equipment required for lifting work can be simplified, and it becomes possible to suspend the load in a stable state while improving workability.

After adjusting the position of the hoisting fixture 7 so that the hoisting point is located above the center of gravity of the reinforcing bar cage 1, the reinforcing bar cage 1 is hoisted using a crane 9 as shown in FIG. 4(c), moved from the lifting device 8 to above the excavation trench 10, and then lowered into the excavation trench 10 to be erected at a specified depth. The erected reinforcing bar cage 1 is then moved to a different position, for example, by a holding device (not shown) installed on the ground surface.

In this state, the lifting device 4 can be easily removed from the reinforcing bar cage 1 together with the crane hook 9a by pulling out the bar 3 from the reinforcing bar cage 1. The removed lifting device 4 can be reused when erecting the next reinforcing bar cage 1.

According to the above-mentioned method of erecting the reinforcing bar cage 1, the erection work of the reinforcing bar cage 1 can be carried out by a crane 9 via the hanging fitting 7 connected to the lifting device 4 simply by attaching the load support fitting 6 of the lifting device 4 to the bar 3 that passes through the reinforcing bar cage 1, making it possible to significantly shorten the work time required for the erection work.

In addition, compared to the conventional method of using a sling or sling wire, the required hanging allowance between the crane 9 and the reinforcing bar cage 1 can be shortened, and the overall height of the reinforcing bar cage 1 can be increased accordingly. As a result, even when the construction site has a low headroom and the concrete structure to be constructed in the excavation trench 10 is a structure that can be constructed at a great depth, the number of reinforcing bar cages 1 connected in the depth direction can be reduced.

As a result, it is possible to significantly shorten the work time required to connect the reinforcing bar cages 1, and also to reduce the number of parts used to connect the reinforcing bar cages 1 together, which contributes to shortening the construction period and reducing construction costs.

The lifting device and reinforcing bar cage installation method of the present invention are not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

For example, in this embodiment, the connecting fitting 5 of the lifting device 4 is configured to include a pair of legs 51 spaced apart and a connecting portion 52 that connects them, but this is not necessarily limited to this. For example, as shown in Figure 9, the connecting fitting 5 may be made of a long steel plate, and a pair of load support fittings 6 may be provided near both sides of the connecting fitting 5.

In addition, in this embodiment, the reinforcing bar cage 1 is suspended by the crane 9 via the lifting device 4, but the lifting machine is not limited to the crane 9, and the reinforcing bar cage 1 may also be used, for example, to construct a cast-in-place concrete pile in an underground hole.

Furthermore, in this embodiment, in the method of erecting the reinforcing bar cage 1, the lifting device 4 is installed on the reinforcing bar cage 1 while being suspended by the crane 9, but the procedure for installing the lifting device 4 is not limited to this.

In addition, the erection device 8 does not necessarily have to be used for erecting the reinforcing bar cage 1. For example, a lifting device 4 may be provided on the reinforcing bar cage 1 placed in a lying position on the ground, and the cage may be erected by a crane 9 using the lifting device 4.

1 Reinforcement cage 1a Vertical bar 1b Horizontal bar 2 Reinforcement member 2a Upper frame body 2b Lower frame body 2c Connecting material 2d Connection jig 3 Bar (mounting rod)
4. Lifting device (for lifting rebar cage)
4' Lifting device (for erection device)
5 Connection fitting 6 Load support fitting 61 Main body portion 62 Semicircular groove portion 6a Through hole portion 7 Suspension fitting 71 Shackle main body 71a Through hole 72 Shackle pin 73 Nut 8 Raising device 81 Frame main body 81a Bottom frame 81b Wall frame 82 Wheel portion 83 Suspension device installation portion 831 Protruding member 831a Bearing 832 Chain member 833 One U-shaped ring 833a Pin 834 The other U-shaped ring 834a Pin (mounting rod)
9 Crane 9a Crane hook 10 Excavation trench (underground excavation section)

Claims (2)

A load support bracket attached to a bar that penetrates the reinforcing bar cage;
and a connecting fitting for connecting the load support fitting to a hanging fitting that is engaged with a crane hook ,
The hanging hardware is connected to the connecting hardware by using a hanging hardware attachment hole provided in the connecting hardware,
The load support fittings are connected to the connecting fittings in a pair in parallel with a gap therebetween, and each of the load support fittings is provided with a through hole through which the bar is passed,
The through-holes of both are arranged so that their central axes are parallel to the hanging hardware mounting hole,
A lifting device characterized in that the bar is movably attached to the load support bracket. A method for erecting a reinforcing bar cage in an underground excavation using the lifting device according to claim 1, comprising:
The reinforcing bar cage in a lying position is placed on the erecting device in a lying position,
A pin installed on the erection device is inserted into the through hole of the load support bracket constituting the lifting device,
The crane hook is engaged with the hanging fitting provided on the connecting fitting, and the reinforcing bar cage is raised together with the raising device.
After attaching the load support bracket to the bar that passes through the reinforcing bar cage instead of the pin ,
A method for erecting a reinforcing bar cage, comprising the steps of: using a lifting machine to suspend the reinforcing bar cage via the hoisting fittings and lowering it into the underground excavation section;

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