JPS5939017B2 - Grab bucket grasp amount detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a grasping amount detecting device for a grab bucket, and more particularly to a grasping amount detecting device for a grab bucket that picks up loose materials such as coal, ore, and gravel.

Generally, when loading and unloading bulk materials such as coal, ore, and gravel from a ship or the like, a grab bucket as shown in FIG. 1 is used.

As shown in the figure, the grab bucket 2 is composed of two symmetrical shells 2at2b, and each shell 2a, 2b is rotatably joined at a joint 4.

One end of an opening/closing rope 6 is connected to the joint portion 4 .

Furthermore, one end of a shell hanging rope 3a t 3b is connected to the bottom surface of each shell 2 a , 2 b , and the other end of the shell hanging rope 3 a > 3 b is connected to the support member 8 .

One end of a support rope 10 is connected to the support member 8 .

The other end of the opening/closing rope 6 is wound around an opening/closing drum 16 connected to the rotating shaft of an opening/closing motor 14 via a roller 12 .

The other end of the support rope 10 is wound around a support drum 22 connected to a rotating shaft of a support motor 20 via a roller 18 .

The operation of such a grab bucket will be explained.

The opening/closing operation of the grab bucket is performed by driving the opening/closing drum 16 with the opening/closing motor 14 to wind up and unwind the opening/closing rope 6.

Moreover, if the opening/closing rope 6 and the support rope 10 are wound up and unwound at a constant speed, the grab bucket moves up and down with its mouth closed or with its mouth open.

These grab buckets usually have a rated load, so it is necessary to detect the gripping amount (hoisting load) of the grab bucket from the perspective of equipment protection and to ensure that this gripping amount does not exceed the rated load. occurs.

Conventionally, in order to detect the amount of grab buckets grabbed, the detection value of the crane's in-machine belt wear within a certain period of time and the number of times the grab bucket was grabbed within this certain period of time were used.
This was done by calculating the average amount of grip per V grip.

However, since the average gripping amount is calculated, the accurate gripping amount per grip cannot be detected, and there is a problem that the gripping amount may exceed the rated load.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a grasping amount detection device for a grab bucket that can accurately detect the grasping amount for each grabbing of a grab bucket.

The grabbing amount detection device for a grab bucket according to the present invention includes an opening/closing motor that opens and closes the grab bucket by winding or unwinding an opening/closing rope, and a support that reciprocates the grab bucket by winding or unwinding a support rope. a current detector that detects the current value of at least one of the motors; a computing unit that computes the gripping amount of the grab bucket from the current value detected by the current detector; The comparator includes a comparator that compares the current value with a preset value, and avoids the calculation by the calculator when the motor is accelerating or decelerating, and calculates the current value when the motor is rotating at a constant speed. This is done using

Next, the basic theory underlying this invention will be explained.

The inventors investigated the relationship between the current flowing through the opening/closing motor and support motor and the gripping amount of the grab bucket when the opening/closing motor and support motor rotate at a constant speed, avoiding acceleration and deceleration of the opening/closing motor and support motor. However, the results shown in FIGS. 2 to 4 were obtained.

Figure 2 shows the relationship between the current value of the opening/closing motor and the amount of grip,
FIG. 3 shows the relationship between the current value of the support motor and the amount of grip.

Moreover, FIG. 4 shows the relationship between the current value and the gripping amount when the current flowing through the opening/closing motor and the current flowing through the support motor are added.

As can be understood from these figures, the current value of each motor and the amount of grip are approximately proportional.

Therefore, if any one of the current value of the opening/closing motor, the current value of the support motor, or the sum of the current values of the opening/closing motor and the support motor is detected, the grab bucket can be detected from the relationship between the current value and the gripping amount. The amount of grip can be detected.

Note that, as is clear from FIG. 4, it is preferable to detect the amount of packets grabbed using the total value of the currents of the opening/closing motor and the support motor.

Next, one embodiment of the present invention will be described in detail with reference to the drawings.

This embodiment is shown in FIG. In FIG. 5, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and their explanations are omitted.

As shown in the figure, the opening/closing motor 14 and the support motor 20
are connected to resistors R0 and R2, respectively.

Each of the resistors R1J and R2 is connected to a current detector 24.

The current detector 24 detects the current value of the opening/closing motor 14, the current value of the support motor 20, or the current value of the opening/closing motor 14 and the support motor 20.

Therefore, it is not necessary to connect to the opening/closing motor 14 and the support motor 20 as shown in the figure, and it may be connected only to the opening/closing motor 14 or the support motor 20.

The current detector 24 is connected to a calculator 26 that calculates the gripping amount of the grab bucket from the current value detected by the current detector 24.

The calculator 26 calculates the gripping amount of the grab bucket by, for example, multiplying the detected current value by a proportionality constant.

The grip amount calculated by the calculator 26 is input to a comparator 30, and is compared with a preset value set by a grip position setting device 28 provided on the operation desk.

The comparator 30 calculates the difference between the calculated gripping amount and the set value, and when this difference exceeds a predetermined tolerance range or when this difference is less than a predetermined tolerance range, the driver to generate a visual or audible warning.

In response to this warning, the driver takes countermeasures such as changing the location where the loose object is grabbed or adjusting the length of the support rope to adjust the amount of grasping.

If the rated gripping amount is set as a setting value in the gripping position setting device 28, a warning will be issued if the rated gripping amount is exceeded due to excessive gripping, so the equipment can be protected by stopping hoisting due to the warning, etc. It can also be used as a safety device.

As explained above, according to the present invention, since the gripping amount is determined from the motor current value, the gripping amount for each grab of the grab bucket can be accurately detected, overload gripping can be prevented, and the average In addition to being able to improve cargo handling efficiency by bringing the grasping amount close to the rated grasping amount, it also has the excellent effect of being able to detect the amount of cargo being handled from the grasping amount for each grasp.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional grab bucket, FIGS. 2 to 4 are diagrams showing the relationship between the motor current value and the grab amount of the grab bucket, and FIG. 5 is a diagram of a conventional grab bucket according to the second invention. FIG. 2 is a block diagram showing one embodiment. 2... Grab bucket, 6... Opening/closing rope, 14... Opening/closing motor, 10...
Support rope, 20...Support motor, 24...
...Current detector, 26...Arithmetic unit, 30...
...Comparator.

Claims (1)

[Claims] 1 Current detection that detects the current value of at least one of the opening/closing motor that opens and closes the grab bucket by winding or unwinding the opening/closing rope and the support motor that reciprocates the grab bucket by winding or unwinding the support rope. a computing unit that computes the gripping amount of the grab bucket from the current value detected by the current detector when the motor whose current is to be detected by the current detector is rotating at a constant speed; and the computing unit. A grasping amount detection device for a grab bucket, comprising a comparator that compares the grasping amount calculated by the above with a preset setting value.