JPS6133499A - Crane - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to cranes, especially when a hanging device or the like gets caught on an obstacle, causing an excessive load on the wire rope (this load is called a snag load). However, the present invention relates to a crane equipped with a winding control device for a snag load that detects the occurrence of this snag load and stops winding the wire loop.

[Background of the invention]

Generally, when unloading a container loaded on a ship, the wire rope is wound up and undone by a trolley running on a crane boom stretched out on top of the ship, or by a take-up drum of a hoist installed on a crane girder. This is done by raising and lowering the hanging tool that is suspended by the wire rogue Vcg. During container hoisting work, if the hoist or the corner of the container gets caught in the cell guide due to rolling of the ship, a snag load occurs in the wire rope. Since a snag load can cause damage to the hoisting device and even the crane structure, it is necessary to immediately stop winding the wire rope.

As a conventional measure against the occurrence of snag load, the rope sheave 1 installed in the roping route, for example, the bracket of the rope sheave installed on the trolley frame,
A load cell is installed, and when the load cell detects a predetermined excessive load, a brake device is activated to stop the hoisting device. FIG. 5 is a diagram showing changes in the tension of the wire rope from the occurrence of a snag load until the hoist stops. In this diagram, point A is the point where the hoist is caught and a snag load occurs.

Point B is the snag load detection point by the load cell, point 0 is the point at which the brake device is activated, point D is the point at which the drive motor connected to the winding increase drum is turned off, and point E is at which the drive of the winding drum stops. Each point is shown.

As can be seen from Fig. 5, a dead −'bana (dead band) is set for the load cell in consideration of swinging equipment, suspended loads, wire rope swings, eccentric loads, etc.
The load cell detects a snag load and stops the hoisting device only when the excessive load exceeds this dead band. Furthermore, due to a delay in the operation of the brake device, a delay in the stopping of the drive motor, etc., a considerable amount of time is required from the occurrence of system load to the time when the winding of the wire rope is stopped. Therefore, until the winding of the wire rope is stopped, this snag load places a burden on the shear wire rope, hoist, and other crane structures, impairing their durability, and even causing the wire rope to break. There was a risk that this could lead to a major accident.

[Purpose of the invention]

The present invention has been made in consideration of the problems of the prior art, and
The purpose is to provide a crane that can quickly detect the occurrence of a snag load and can perform the process from the occurrence of the snag load to the repeated winding and stopping of the wire rope in a short period of time.

[Summary of the invention]

The rotational speed of the rotary drive unit of the hoist and the rotational speed of the rope sheave are in a proportional relationship in normal cargo handling operations. However, if the wire rope gets caught on an obstacle and is blocked, the wire rope stretches and the rotational drive part of the hoisting root rotates, but on the other hand, the sheave installed on the hoist has a slow rotation speed. , the rotation speed becomes lower. In other words, when there is a difference between the rotational speed of the rotary drive unit and the rotational speed of the sheave installed on the hanging tool, it is when the hanging rod or the like is caught. Therefore, the inventors compared the rotational speeds of the two and detected when there was a difference between the rotational speeds of the two. The present invention was developed based on the knowledge that the occurrence of snag loads can be quickly dealt with.

The present invention installs rotation speed detectors in the rotation drive part of a wire rope hoist and the sheath of a rope sheave installed on a typical roping route, and compares the rotation speed detected by these detectors with the rotation speed. When the difference in rotational speed exceeds a predetermined value, the brake device is activated to stop the drive of the winding drum.With this configuration, the above-mentioned The purpose will be achieved.

[Embodiments of the invention]

Next, embodiments of the present invention will be described based on the drawings.

1 and 2 are diagrams showing an embodiment of a crane according to the present invention. In these figures, a girder 12γ is supported horizontally by legs 10, and a boom 16 is installed at the tip of the girder 12 to extend toward the sea side and extend above a ship 42.A trolley 14 is mounted on the girder 12. "It is assembled so that it can run in the longitudinal direction. Rope sheaves 20 (20A to 20D) and 21 (21A to 21
D), but the trolley 14 has rope sheaves 22 (22A~
22D), 24 (24A to 24D), 23 (2!IA to 23D) are installed on the hanging tool 15, and a rope sheave 25 (25A to 25D) is installed at the end of the pool 16, respectively. A winding device 18 is placed on the girder 12, and four wire ropes 26 (26A to 26D) are drawn from a winding drum 19 in this winding device 18.
extends, rope sheave 20.21.22.23.24
25 and connected to a tilting device 28 provided at the end of the pool.

The winding device 18 is as shown in FIG.

The winding drum 19 is a decelerator 56 and a brake device 34
This drive motor 56 and brake equipment fit! +4 is operated to wind and unwind the wire rope 26 by the winding drum 19, thereby raising and lowering the hanging tool 15.

In FIG. 1, reference numeral 14A denotes a driver's cab, and the driver's cab 14A is used to move the trolley 14 horizontally and raise and lower the hanger 15, thereby handling the container 40.

Rope sheave 23 (25
8 to 25D) are each equipped with a rotation speed detector 50 (
30A-30D) are installed.

A rotational speed detector 51 is also installed on the rotational drive shaft 19A of the winding tom 19-. Each rotation speed detector 50, 51 is connected to a rotation speed comparator 52. Electromagnetic flux pickup sensors are used in the detectors 50 and 61 to output 2 and 4' pulse signals to the comparator 32, and the comparator 32 converts these pulse signals into pulse ratios, respectively. It's meant to be compared. Now, if the number of pulses output by the rotation speed detector 31 is N, and the number of pulses output by the rotation speed detector jo (3oA-50D) is Na and N(l, respectively, then the comparator 32 calculates N
and Na#N(l), and when the pulse ratio exceeds a predetermined pulse ratio, an output is sent to the brake control device 5 and motor control device 55, and the brake control device 35 operates the brake device 54. In addition, the motor control device′
55 to stop the rotation of the motor 5B. It should be noted that the set reference pulse ratio for generating the output signal for operating the control devices 5 and 55 is set to be slightly larger, but with a margin. In the conventional method of detecting the snag load using a load cell installed in the rope sheave, a certain amount of ae
Although it is necessary to set the ad-band, the rotational speed of the rope sheave 23 and the rotary drive shaft 19A is hardly affected by the rolling of the ship 42, the swinging of the wire rope 26 or the hanging equipment 16, or eccentric loads. , only rj
It is only necessary to provide a deaa-band region, and the detection of the snag load becomes faster.

Suppose that when the wire rope 26 is wound around the first winding drum 19 and the container 40 is lifted up, the corner portion 15G of the lifting tool 15 gets caught in the cell guide 45.
The rotation speed of the rope sheave 23C is the same as that of the other sheaves 23A and 23.
B, 2! , -D becomes sharply smaller. On the other hand, since the wire rope 26 of the winding drum 19 has elongation, the number of revolutions does not change. Therefore, the pulse ratio suddenly becomes thicker and the comparator 52 detects this and the controller 53.6
5 is activated, and as a result, the winding drum 19 stops winding the shear wire f26. This state is shown by solid lines in the figure, in which reference numeral A1 indicates the snag load generation point, reference numeral stop point, and reference numeral E/ indicates the rotation stop point of the winding drum. In addition, in this Figure 5, the broken line indicates the change in tension of the wire rope until the take-up drum stops in a conventional crane.
The time required for the winding of the wire rope to stop after a snag load occurs in the wire rope is T compared to the conventional crane in the crane according to this embodiment.
, -T is shorter.

As described above, in this embodiment, the time from the occurrence of the snag load to the detection thereof is shortened, and the snag load can be kept small accordingly.

Also, so far we have explained the case where snag load occurs on the wire rope when lifting a container.
The present invention can also be applied to cases where a corner portion of the container hits an obstacle during lifting and lowering of the container and the container cannot be landed normally.

That is, when the corner portion 40C of the container 40 is raised by an obstacle during the container hoisting and lowering operation, as shown in FIG. 2, for example, when the horizontal descent of the container 40 is prevented,
Although the rotational speed of the rotary drum 19 does not change, since the wire rope 26C is loosened, the rotational speed of the sheath 7'23G becomes small, and the pulse ratio "L" becomes larger. Then, as in the case of the occurrence of a snag load C, the comparator 52
5 is activated to stop unwinding of the wire lobe 26 by the winding cart 2 motor 19. In addition, in the above embodiment, the rope sheave 25 (25A to 25
Although an example is shown in which the rotation speed detector 50 is installed in D), the present invention is not limited to this, and the same effect can be achieved by installing it in any of the rope sheaves of each roping route A and D. However, considering the elongation of the wire lobes 26, it is preferable to install the wire lobes 26 in a rope sheave located away from the winding tom 19 on the roping path.

In addition, in the above embodiment, a crane of the 4-A suspension type was explained in which four shafts were installed on the lifting device 13, but the present invention can be applied to various types of cranes such as one-point suspension, two-point suspension, etc. Needless to say.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, the time required to detect the occurrence of a snag load is shortened.
It is possible to keep the generated snag load small and gain a lane.

[Brief explanation of the drawing]

Fig. 1 is a front view of the crane according to this embodiment, Fig. 2 is a perspective view showing its roping route, Fig. 6 is a schematic diagram showing the drive control mechanism of the wire rope hoisting device, and Fig. 4 is this embodiment. FIG. 5 is a diagram showing changes in Rose tension after snag load occurs until winding of the wire rope is stopped by a crane related to the above, and FIG. 5 is a diagram showing changes in tension in the same rope by a conventional crane. 13... Hanging equipment, 14... Trolley, 19.
... Winding tram, 20.21.22.25, 24.25... Rope sheave, 26... Wire robe, 60 (RoOA~50D)... Rotation detector. 62... Rotation speed comparator, 34... Brake device, 56... Drive morph, 40... Container. Agent Tatsu Unuma Figure 1 Figure 2 Figure 4 Figure 5 Katama

Claims (1)

[Claims] (1) A wire rope extends from a hoist equipped with a winding drum connected to a drive motor and a brake device that applies brakes to the winding drum, and is sequentially passed around rope sheaves to form one or more roping paths. In a crane that lifts and lowers a hanging device suspended from a wire rope by winding and unwinding a wire rope on a winding drum, a rotational speed detection device is installed in the rotation drive unit of the hoist and the rope sheave installed in each roping route. The number of revolutions detected by these detectors is compared with a number of revolutions comparator, and when the difference in the number of revolutions exceeds a predetermined value, the brake device is activated to drive the winding drum. A crane characterized in that it can be stopped.