JPS6222917B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the gripping amount of a grab bucket.

For example, as shown in FIG. 1, when unloading bulk materials 2 such as coal, ore, gravel, etc. from a ship 1, a grab bucket crane 3 is generally used.

This grab bucket crane 3 includes a crane girder 4 protruding from the quay toward the side of the ship 1;
A main trolley 5 that reciprocates on this crane girder 4, a grab bucket 10 that is suspended by a support wire 8 and an opening/closing wire 9 via guide rollers 6 and 7 provided on this main trolley 5, respectively. It consists of a crane hopper 11 into which raw materials 2 unloaded by a grab bucket 10 are input.

As shown in detail in FIG. 2, the grab bucket 10 includes a pair of left and right shells 10a, and each shell 1.
A pivot member 10b rotatably pivots 0a.
and a support member 10d that suspends and supports each shell 10a via a wire 10c provided on the bottom surface of each shell 10a.

One end of the opening/closing wire 9 is connected to the pivoting member 10b of the grab bucket 10, and the opening/closing wire 9 is wound around a drum 12, which is rotated in forward and reverse directions by a reversible motor 13. Therefore, the grab bucket 10 is opened and closed.

Also, the support member 10 in the grab bucket 10
One end of the support wire 8 is connected to d, and the support wire 8 is wound around a drum 14. By rotating this drum 14 forward and backward with a reversible motor 15, the grab bucket 10 is rotated. Moved up and down.

That is, by winding up or letting out the support wire 8 and the opening/closing wire 9 at a constant speed, the grab bucket 10 moves up and down with its mouth closed or with its mouth open.

By the way, for such grab bucket cranes, the rated load is usually determined, so from the standpoint of equipment protection, it is necessary to control the gripping amount of the grab bucket to prevent the gripping amount from exceeding the rated load. There is.

Conventionally, the following two methods have been adopted to control the amount of grip by a grab bucket.

The first method is to adjust the baffle plate in the grab bucket according to the properties of the bulk raw materials, such as particle size, moisture content, etc., so that the amount of one handful in the grab bucket does not exceed the rated load. be.

However, this method has the problem that cargo handling efficiency decreases because the variation in the amount of grab buckets per grab increases, and the baffle plates are adjusted so that the amount of grabs per grab is less than the rated load.

The second method is to calculate the average gripping amount per grab from the detected value of the crane's internal belt wear and the number of reciprocations of the grab bucket, and if the gripping amount exceeds the rated load, This is a method of controlling the gripping amount by adjusting the slack length of the support wire at the time when the grab bucket grabs the bulk material, that is, when the grab bucket is closed.

However, with this method, the average gripping amount is calculated, and based on this, the operator manually operates the sinking amount adjuster to adjust the slack length of the support wire, so it is possible to accurately calculate the amount of grip per grab bucket. There was a problem in that the gripping amount could not be determined, and therefore the sinking amount and the rated load did not necessarily match, and the gripping amount could exceed the rated load.

The present invention has been made to solve the problems of the conventional methods as described above, and an example of its implementation will be described below with reference to FIG. 3.

As shown in FIG. 3, the opening/closing wire drum 1
A wire feed-out length detector 16 such as a pulse generator for detecting the feed-out length of the opening/closing wire 9 is provided at the shaft end of the support wire drum 14, and a wire feed-out length detector 16, such as a pulse generator, is provided at the shaft end of the support wire drum 14 to detect the feed-out length of the support wire 8. A wire payout length detector 17, such as a pulse generator, is provided to detect the length of the wire.

A resistor 18 is connected to the opening/closing wire drum drive motor 13, a resistor 19 is connected to the support wire drum drive motor 15, and a current detector 20 is connected to the resistors 18 and 19. The total current of motors 13 and 15 is detected.

The motor 1 detected by the current detector 20 is connected to one output side of the current detector 20.
Grab bucket 1 from the change point of current value in 3.15
A landing detector 21 is connected to detect the landing of 0 on the bulk raw material 2.

As shown in FIG. 4, this landing detector 21 detects that the current value when the motors 13 and 15 are feeding out the wire is
Detects sudden decreases due to upward landing,
This is how the landing is detected.

In addition, each point B, C, D, E shown in FIG.
This corresponds to points B, C, D, and E shown in FIG. 1, and there is a change in the current value that suddenly decreases at the landing point E, which is sufficiently detectable.

The landing detection signal from the landing detector 21 is input to the control device 22, and the motors 13 and 15 are immediately stopped via the control device 22.

On the other hand, the landing detection signal from the landing detector 21 is input as a calculation start signal to the wire feeding length calculator 23 which calculates the wire feeding length by the wire feeding length detector 17. , the length of each wire 8 to be paid out after the grab bucket 10 lands is calculated.

The calculated value by the wire unwinding length calculator 23 is given as an input signal to the control device 22, and the calculated value after landing is set in advance so that the calculated value of the wire unwinding length after landing becomes a predetermined wire slack length. Based on the standard payout amount of the wire, each motor 15 is rotated forward or reverse by the control device 22, the length of each wire 8 is adjusted to a predetermined amount of slack, and the amount of sinking of the grab bucket 10 is controlled. The gripping amount is controlled at a constant level.

Further, on the other output side of the current detector 20,
A grip amount calculator 24 is connected, and the grip amount calculator 24 calculates the grip amount of the grab bucket 10 by multiplying the detected current value by a proportionality constant.

The calculated value from the gripping amount calculator 24 is input to a comparator 25, and is compared with a target setting value set in advance by the gripping amount setting device 26, and if the gripping amount exceeds the target setting value. If there is
The difference between the calculated gripping amount and the set value is calculated, and a signal corresponding to this difference is input to the sinking amount calculator 27.
The amount of sinking is calculated based on the signal input from
The calculated value is input to the control device 22.

Then, in the control device 22, based on the input calculation results, each motor 15 is
The amount of slack in each wire 8 can be adjusted by rotating it forward or backward.

In other words, if the gripping amount is larger than the set value at any gripping time, the slack length is shortened and the amount of sinking is reduced in the next gripping, and if the gripping amount is smaller than the set value for,
The grip bucket 10 is controlled so that the slack length is increased to increase the amount of sinking during the next grip.
The gripping amount of the grab bucket 10 is automatically controlled to be close to the set value, for example, the rated load, and the slack length adjustment of each wire 8 to control the sinking amount is performed at the landing point of the grab bucket 10 on the two sides of the bulk material. The amount of gripping can be controlled extremely accurately and without being affected by changes in sea level due to low tide and high tide during cargo handling, and changes in the floating amount due to a reduction in the load inside the vessel 1 due to cargo handling. can be done.

In addition, the present inventors et al.
5, the current of each motor 13, 15 when rotating at a constant speed, avoiding acceleration and deceleration,
When the relationship between the gripping amount of the grab bucket 10 and the gripping amount was investigated, the results shown in FIGS. 5A, B, and C were obtained.

That is, FIG. 5A shows the relationship between the total current value of the opening/closing wire drum drive motor 13 and the support wire drum drive motor 15 and the amount of grip, and FIG. FIG. 5C shows the relationship between the current value and the gripping amount, and FIG.
3 shows the relationship between the current value and the gripping amount, but as can be understood from FIGS. 5A, B, and C, in each case, the current value of each motor 13, 15 and the gripping amount are is almost proportional to the total current value of the opening/closing wire drum driving motor 13 and the supporting wire drum driving motor 15, or the current value of the supporting wire drum driving motor 15, or the current value of the opening/closing wire drum driving motor 13. If any one of these is detected by the current detector 20, the grasping amount can be determined.

However, as is clear from FIG. 5A, it is preferable to calculate the gripping amount of the grab bucket bag 10 using the total current value of each motor 13, 15 because there is less variation.

Next, the gripping amount control method according to the present invention will be explained with reference to FIGS. 1, 3, and 6.

Now, as shown in FIG. 1, the grab bucket cart 10 suspended by the support wire 8 and opening/closing wire 9 via the guide rollers 6 and 7 of the main trolley 5 is lifted onto the hopper 11 by the driver's operation. Ship 1 with main trolley 5 from point A
Move laterally.

Simultaneously with the start of movement of the main trolley 5, the wire payout length detectors 16 and 17 provided on the opening/closing wire drum 12 and the support wire drum 14 are activated, and the respective signals indicate the wire payout length in FIG. is input to the arithmetic unit 23,
Calculate the length of each wire 8, 9.

And when grab bucket 10 comes to point B,
The driver moves each wire 8,
Perform the feeding operation in step 9.

When the grab bucket 10 descends to point C,
The manual operation by the driver is replaced by automatic operation, which will be described later, and the grab bucket 10 further descends and descends in a decelerated state below point D.

When the grab bucket 10 lands on point E on the bulk material 2, the landing detector 21 detects that the current values of the opening/closing wire drum drive motor 13 and the support wire drum drive motor 15 change due to the load change. The landing detection signal is sent to the control device 22, and each motor 1
Activate the brakes 3 and 15 to stop the grab bucket cart 10 from descending.

In addition, each wire feeding length detector 16,1
7 and the landing detection signal based on the change in the current value of each of the motors 13 and 15 described above, the distance L between the crane girder 4 and the point E on the bulk material 2 in the ship 1 is determined by the distance L between the wire feeding It is calculated by the length calculator 23.

In FIG. 1, l ₁ and l ₂ indicate automatic control ranges, l ₂ indicates constant speed control for reasons described later, and l ₁ indicates a deceleration range from l ₂ speed.

l ₁ (deceleration distance) and l ₂ (constant speed) may be controlled, for example, at a constant ratio to the distance L obtained by the above calculation, and l ₁ and l ₂ can be controlled by changing the distance L. can be corrected every time or every set number of times, and even if the distance L changes due to the situation of the bulk raw material 2 or the difference in tide, efficient cargo handling can be carried out without damage to the ship by the grab bucket 10. be able to.

Further, the landing detector 21 detects that the grab bucket 10 has landed on the bulk raw material 2,
Even if the brakes of each motor 13, 15 are activated at that point, each wire drum 12, 14 will immediately
The support wire 8 and opening/closing wire 9 are fed out due to inertia without stopping.

In this case, the length F of the wire 8 after it lands
is calculated by the wire unwinding length calculator 23 via the wire unwinding length detector 17, and the calculation output is input to the control device 22, and the wire unwinding length calculation value after landing is determined to be the predetermined wire slack length. The controller 22 controls each motor 1 so that
5 is driven to adjust the length of each wire 8 to make the amount of slack a predetermined value (wire feeding length adjustment amount = standard feeding amount - F).

After the grab bucket 10 lands on the bulk material 2, it automatically enters the closing operation (grasping operation), and at the same time,
Each wire 8 of the amount of payout length adjustment calculated above
is fed out, and the grab bucket 10 completes the closing operation and is automatically hoisted, and between D and C, that is, in the _l2 zone, the current values of each motor 13 and 15 are input to the grip amount calculator 24, and the grab bucket A batch amount of 10 is calculated.

Since the winding speed in this l ₂ zone is controlled at a constant speed, it is proportional to the gripping amount, making it possible to accurately calculate the gripping amount.

Then, it is compared with the grasping amount (or current value) set in advance by the setting device 26, and if the grasping amount is within the control range, the next time the payout length of each wire 8 is set using the same standard payout amount. If it is out of the control range, next time the standard payout amount is changed and the payout length of each wire 8 is adjusted.

The grab bucket 10 is manually moved by the driver in the direction of point A from point C, stopped at point A,
A grab bucket 10 is opened on a hopper 11 and bulk raw material 2 is dropped.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of a grab bucket truck crane to which the method of the present invention is applied, Fig. 2 is an explanatory diagram showing details of the grab bucket truck, Fig. 3 is a block diagram showing an example of implementation of the method of the present invention, and Fig. 4 Figures 5A, B, and C are graphs showing changes in the current value of the wire drum drive motor when landing on a grab bucket.
6 is a graph showing the relationship between the grab amount in a grab bucket and the current value of the wire drum driving motor, and FIG. 6 is a flowchart of the operation of the grab bucket truck crane according to the method of the present invention.

Claims (1)

[Claims] 1. In a grab bucket truck crane, detect the current when the wire is fed out from at least one of the grab bucket opening/closing wire drum driving motor and the support wire drum driving motor, and from the change in this detected current, transfer the current to the bulk material side of the grab bucket. detecting the landing of the grab bucket, and adjusting the slack length of the support wire based on the landing detection point, controlling the sinking amount of the grab bucket,
Compare the detected current of the motor during hoisting of the grab bucket after grasping the bulk material or the gripping amount of the grab bucket obtained from this detected current with a predetermined target setting value, and based on the comparison result. A method for controlling the gripping amount of a grab bucket, comprising: determining the slack length of the wire at the time of grabbing in the next landing based on the next landing detection time point, and adjusting the sinking amount of the grab bucket.