JPH0718701Y2 - Jib restraint system for steel tower construction cranes - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a jib restraint device for a tower construction crane.

[Prior Art] First, a jib restraint device generally used in a mobile crane will be briefly described. FIG. 6 shows a mobile crane in which a jib 2 is movably attached to the front part of a revolving structure 1 and an A frame 3 is attached from the middle part to the rear part.
In such a mobile crane, the horizontal distance X between the mounting portion of the jib 2 and the top of the A frame 3 is larger than the vertical distance Y, and the undulating range of the jib 2 is from about horizontal to about 80 °. Since it is relatively small, it is possible to install the jib restraint device 4 which is an expandable cylinder in which an outer cylinder and an inner cylinder are combined. The maximum standing angle of the jib 2 is set to 80 ° from the horizontal, which is the maximum angle when the jib 2 can be tilted by its own weight even if there is wind pressure.

On the other hand, describing an example of the size of a steel tower to be constructed, its height is, for example, 50 meters, and it is formed in a tapered triangular shape when viewed from the side, and its top opening size is about 1.2 meters. And set very small. A crane for constructing such a steel tower has a mast located at the center of the steel tower to be constructed, and the upper end of the mast is set to have an outer peripheral dimension of about 0.9 m, which is smaller than the above-mentioned opening size of the steel tower of about 1.2 m. A crane main body capable of turning is mounted, and a jib is attached to the crane main body so that the jib can rise and fall, and an A frame having a long height is attached.
It is a climbing crane that builds a steel tower by successively adding masts from the bottom by a hoisting method, and when assembling the upper part of the steel tower, the crane body is climbed to a high position of 50 meters or more above the steel tower construction height. At the same time, the jib must be raised up to near the upright position and the tower building members must be lifted, so the maximum standing angle during work is 87 °, which is far beyond the maximum angle of 80 ° for tilting the jib by its own weight. It is set, and in this state, the weight of the entire crane body comes to almost the center of the mast, and it is possible to climb in a stable state. When the steel tower is not assembled and is not in operation, the mast is sequentially removed from the lower side in reverse of the above-described construction of the steel tower, so that the entire crane body is lowered inside the steel tower to be dismantled and removed. At this time, when lowering the crane body in the top of the tower, it is necessary to raise the jib upright (90 °) so that the jib and the tower do not interfere with each other. Here, the setting of the jib rising angles of 87 ° and 90 ° is performed by a limit switch (not shown).

FIG. 7 and FIG. 8 show an example of such a tower construction crane. The mast 5 is supported by a support mast 6 that also serves as a climbing device, and a swingable crane body 7 is mounted on the upper end of the mast 5. As shown in FIG. 8, the crane body 7 is set to have an outer peripheral size smaller than the opening size of the top of the steel tower 10 because it is necessary to lower the inside of the steel tower 10 after the assembly of the steel tower 10 is completed. On one end side of the crane body 7, a jib 8 is attached so as to be capable of undulating, and an A frame 9 having a long height from one end side to the other end side is installed. Further, the crane main body 7 is provided with a winch for undulating the jib 8 and hoisting a suspended load.

[Problems to be Solved by the Invention] In such a tower construction crane, when the tower 10 is assembled, the jib 8 is lowered from the horizontal to a considerably lower position as indicated by a chain double-dashed line I in FIG. When the crane main body 7 having the jib 8 is lowered in the tower 10 after the completion of assembly, the size of the jib 8 needs to be reduced so that the jib 8 stands upright (90 °) as shown by the chain double-dashed line II in FIG. Let
Thus, the undulating range of the jib 8 is about twice as large as that of the mobile crane described above. Further, for the same purpose of lowering the inside of the steel tower 10, the horizontal distance X between the mounting portion of the jib 8 and the top of the A frame 9 has to be remarkably smaller than the vertical distance Y. A with various heights
It is frame 9. For this reason, even if an attempt is made to employ a jib restraint device composed of a telescopic cylinder used in a mobile crane, the difference between the minimum length and the maximum length of the device is too large due to the large undulating range of the jib 8. There was a problem that could not be adopted. In addition, there are cases where the jib 8 is raised to 80 ° or more to operate due to the required work performance,
In the case of a headwind, if you try to lower the jib 8 against the wind pressure, the weight of the jib is not enough, and there is a problem that the force to push the jib 8 forward is necessary.

The present invention has been made in view of the above, and an object thereof is to provide an optimal jib restraint device for a crane for constructing a steel tower.

[Means for Solving the Problems] The jib restraint device of the present invention is for achieving the above-mentioned object, and the mast is located at the center of the steel tower to be constructed.
An A frame having a long height is mounted on the upper end of the mast to mount a swivel crane main body having an outer peripheral size smaller than the opening size of the tower top, and to attach a jib to the crane main body so that the jib can rise and fall. In the tower construction crane, in which the mast is sequentially added from the bottom by the method of raising the ground to construct the tower, the one end of the rod-shaped first support can be freely swung on the back part near the root of the jib. A compression spring that is connected to the top of the A frame at or near the top of the A frame is made up of an expandable cylinder that is a combination of an outer cylinder and an inner cylinder, and is compressed at one end when the expandable cylinder shrinks more than a certain amount. The one end of the second support is swingably connected by a pin, and the other ends of the first support and the second support are connected by a pin so that they can bend each other. The port has a maximum contraction position where the first support is pressed against the back surface of the jib when the jib stands upright and stops, and an extended position where the first support and the jib are separated when the jib falls down. The compression spring pushes out the jib in the direction in which the jib is tilted.

[Operation] When the jib is upright, the second support is in the most contracted state. Further, the compression spring is contracted near the upright position of the jib, and the jib is pushed by the spring force through the first support. When the jib is further tilted, the compression spring expands and the second support reaches the most expanded state, and the back surface of the jib moves away from the first support. When the jib is further pushed down, the second support keeps falling while maintaining the most extended state, and the jib also falls greatly.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. In FIGS. 1 to 3 and 5, the same reference numerals as those in FIGS. 7 and 8 represent the same or corresponding components.

The steel tower construction crane described above, after the steel tower 10 is completed,
Since dismantling and removal cannot be done without lowering the inside, it is necessary to be able to set the descending size of the crane body so that it is less than that according to the opening size at the top of the tower.

A bracket 11 is attached to the rear surface near the base of the jib 8, and one end of a rod-shaped first support 12 is swingably connected to the bracket 11 by a pin 13. At the top of the A frame 9 or in the vicinity thereof, one end of an outer cylinder 14a that constitutes the second support 14 that is a telescopic cylinder is connected by a pin 15, and the inner cylinder 14b is axially connected to the outer cylinder 14a. It is inserted so that it can slide on. An elongated hole 14 for setting the sliding range of the inner cylinder 14b is provided on the peripheral wall of the inner cylinder 14b inserted in the outer cylinder 14a.
c is provided, and the stopper bolt 16 attached to the outer cylinder 14a is inserted into the elongated hole 14c. The long hole 14c
The stopper bolts 16 come into contact with the ends of the second support 14, respectively, so that the maximum contraction position and the maximum expansion position of the second support 14 are restricted. A compression spring 17 is attached between a spring receiving portion provided at the other end of the outer cylinder 14a and a spring receiving portion provided at one end of the inner cylinder 14b. First support 12
The opposite ends of the inner cylinder 14b and the inner cylinder 14b are swingably connected to each other by a pin 18.

FIG. 1 shows the state in which the jib 8 is upright. In this state, the compression spring 17 is contracted, and the inner cylinder 14b is deep inside the outer cylinder 14a. That is, the stopper bolt 16 contacts the right end of the elongated hole 14c of the inner cylinder 14b, and the second support 14 is in the most contracted state. At this time, the jib 8 is pressed by the reaction force of the compression spring 17 via the first support 12 in the direction of the arrow. An end portion of the first support 12 on the pin 18 side is in contact with a receiving plate 8a attached to the back surface of the jib 8. When the jib 8 is tilted down from this state, the jib 8 and the first support 12 are integrally tilted, and the stopper bolt 16 is brought into contact with the left end of the elongated hole 14c of the inner cylinder 14b, so that the first support 14 is maximally moved. The extension state is reached (state of FIG. 3). After that, the second support 14 falls down in the most extended state, and the jib 8 and the first support 12 are separated from each other to be in the state shown in FIG.

FIG. 5 is an explanatory view showing the positional relationship between the swinging position of the jib 8 and the first support 12 and the second support 14, where P-A-A 'is the upright state of the jib 8 and P-B-B' is At the same time when the compression spring 17 is fully extended and there is no force to push the jib 8 forward (the second support 14 is in the most extended state), the first support 12 is moved to the jib 8 side.
, P-C-C 'represents the state in which the tip of the jib 8 is in contact with the ground.

In this way, by the second support 14 consisting of a telescopic cylinder,
It is possible to minimize the sliding range of the jib 8 while generating a spring force by pushing the jib 8 in the direction of tilting the jib 8 upright, and to sufficiently cope with a large undulating range of the jib 8.

Although the compression spring 17 is located on the pin 18 side in the embodiment of the present invention, it may be reversed and brought to the pin 15 side. Further, although the long hole 14c is provided on the inner cylinder 14b side, it goes without saying that it may be provided on the outer cylinder 14a side.

[Effect of the Invention] As described above, according to the jib stopping device of the present invention, it is possible to follow a large jib undulation range from the upright standing state of the jib to the jib descending state below the horizontal level. Further, since the force for pushing the jib forward can be generated only near the upright position of the jib, the jib near the upright position can be lowered even if there is wind pressure. Therefore, it is possible to obtain the optimal jib restraint device for the tower construction crane.

[Brief description of drawings]

1 and 2 are side views showing an embodiment of the present invention,
FIG. 1 shows the jib in an upright position, and FIG. 2 shows the jib in a working position. FIG. 3 is an enlarged side view showing the first support and the second support in FIGS. 1 and 2, and FIG.
FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3, FIG. 5 is an explanatory view showing an operating state of the jib restraint device of the present invention, and FIG. 6 is a side view showing a conventional mobile crane, FIGS. The figure is an explanatory view showing an example of a conventional crane for steel tower construction. 5 ... Mast, 7 ... Crane body, 8 ... Jib, 9 ... A frame, 10 ... Tower, 12 ... First support, 13,15,18 ... Pin,
14 ... Second support, 14a ... Outer cylinder, 14b ... Inner cylinder, 14c ... Oblong hole, 16 ... Stopper bolt, 17 ... Compression spring.

Claims (1)

[Scope of utility model registration request] 1. A mast is located at the center of a steel tower to be constructed, and a swingable crane body having an outer peripheral dimension smaller than the opening dimension of the top of the steel tower is mounted on the upper end of the mast. In the crane for constructing a steel tower, in which a jib is mounted so that it can be undulated, an A frame having a long height is attached, and a mast is sequentially added from the bottom by a hoisting method to construct a steel tower, the vicinity of the base of the jib One end of a rod-shaped first support is swingably connected to the back of the body by a pin, and the top or the vicinity of the A frame is made up of an expandable and contractible cylinder that combines an outer cylinder and an inner cylinder. One end of a second support having a compression spring interposed therein, which is compressed when the telescopic cylinder is contracted by a certain amount or more, is swingably connected by a pin to connect the first support and the second support. The other ends are connected to each other with a pin so that they can be bent, and the second support has a first contraction position where the first support is pressed against the back surface of the jib to stop when the jib stands upright, and a first support when the jib falls down. And a jib having a maximum extension position away from each other, and configured to push the jib in the direction of tilting the jib through the first support by the compression spring near the upright position of the jib. apparatus.