JPS6247791B2 - - 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 general vessel 1;
A main trolley 5 that reciprocates on this crane girder 4, a grab bucket 10 that is suspended by an opening/closing wire 8 and a support 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 FIG. 2, the grab bucket 10 includes a pair of left and right shells 10a, and each shell 10a.
and a wire 10c provided on the bottom surface of each shell 10a.
and a support member 10d that suspends and supports each shell 10a via the support member 10d.

One end of the opening/closing wire 8 is connected to the pivoting member 10b of the grab bucket 10, and the opening/closing wire 8 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 9 is connected to d, and the support wire 9 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 opening/closing wire 8 and the support 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 characteristics 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 of a large variation in the amount of grab buckets, so the baffle plates are adjusted so that the amount of grabs is less than the rated load, which reduces cargo handling efficiency.

The second method is to calculate the average grip amount per grab from the crane's in-machine belt wear detection value and the number of reciprocations of the grab bucket, and if the grab amount exceeds the rated load, the grab bucket 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, the so-called sinking amount adjustment is performed.
This is a method of controlling the amount of grip.

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 support wire drum 1
A wire feed-out length detector 16, such as a pulse generator, for detecting the feed-out length of the support wire 9 is provided at the shaft end of the support wire 4.

A resistor 17 is connected to the opening/closing wire drum drive motor 13, a resistor 18 is connected to the support wire drum drive motor 15, and a current detector 19 is connected to the resistors 17 and 18. The total current of motors 13 and 15 is detected.

Note that the current of either the motors 13 or 15 may be detected by the current detector 19.

20 is for feeding out the opening/closing wire 8, supporting a wire guide support means such as an arbitrary guide sheave in the winding line, or feeding out the support wire 9, and supporting a wire guide support means such as an arbitrary guide sheave in the winding line. The load detector 20, which is a load detector such as a strain gauge, is installed in the wire guide support means, and detects the load of the opening/closing wire 8 or the support wire 9 applied to the support portion of the wire guide support means.

Note that the wire guide and support means for installing the loaded load detector 20 may be provided by separately providing a guide sheave for guiding and supporting the opening/closing wire 8 or the support wire 9 in any structure of the crane 3 shown in FIG. The guide rollers 6 and 7 may be used as they are.

A landing detector 21 is connected to the output side of the loaded load detector 20 and detects landing of the grab bucket 10 on the bulk raw material 2 from the change point of the voltage value detected by the loaded load detector 20. ing.

As shown in FIG.
Detects sudden decreases due to upward landing,
This is how the landing is detected.

Note that the points A, B, C, D, and E shown in Figure 4 correspond to the points A, B, C, D, and E shown in Figure 1, and the landing point E There is a change in which the output voltage value of the load load detector 20 suddenly decreases, which can be detected with sufficient accuracy.

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 16. , the length of the wire 9 that is fed 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, the motor 15 is rotated forward or reverse by the control device 22, the length of the wire 9 is adjusted to a predetermined amount of slack, and the amount of sinking of the grab bucket 10 is controlled to ensure constant gripping. The idea was to control the amount.

Further, a grip amount calculator 24 is connected to the output side of the current detector 19, 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. It is used to calculate.

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.

Based on the input calculation results, the control device 22 rotates the motor 15 in the forward or reverse direction at the next time of gripping, and adjusts the amount of slack in the wire 9.

In other words, if the gripping amount is larger than the set value during any gripping, the slack length is shortened and the sinking amount is controlled to be smaller in the next gripping, so that the gripping amount is less than the set value. If the amount of sinking is small, the amount of sinking will be increased at the next time of gripping, and the amount of gripping of the grab bucket 10 will be automatically controlled to be close to the set value, for example, the rated load. Since the slack length of the wire 9 is adjusted from the landing point of the grab bucket 10 on the two sides of the bulk raw material, it is possible to accurately adjust the slack length of the wire 9, and to adjust the length of the slack in the general vessel 1 due to changes in sea level due to low tide and high tide during cargo handling. The gripping amount can be controlled without being affected by changes in the floating amount due to a decrease in the load.

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 we investigated the relationship between the gripping amount of the grab bucket 10, we obtained the results shown in FIGS. 5A, B, and C.

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 19, 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, which is suspended by the opening/closing wire 8 and the support 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. It moves from point A to the ship 1 side together with the main trolley 5.

Simultaneously with the start of movement of the main trolley 5, the wire payout length detector 16 provided on the support wire drum 14 is activated, and its signal is input to the wire payout length calculator 23 in FIG. Calculate the payout length.

And when grab bucket 10 comes to point B,
The driver performs a feeding operation of each of the wires 8 and 9 in order to land the grab bucket 10 at point E on the bulk raw material 2 in the general vessel 1.

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 opening/closing wire 8
Alternatively, the landing detector 21 detects a change in the output voltage value of the load detector 20 provided at the support portion of the guide support means of the support wire 9, and sends the landing detection signal to the control device 22. , actuate the brakes of the respective motors 13 and 15 to stop the descent of the grab bucket cart 10.

Further, by the operation of the wire payout length detector 16 and the landing detection signal based on the output voltage value change of the load load detector 20 described above, the E The distance L to the point is calculated by the wire payout 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 at a constant ratio, for example, to the distance L obtained by the above calculation, and may be controlled by changing the distance L by fluctuations in the distance L.
l ₁ and l ₂ can be corrected each time or each set number of times, and even if the distance L changes depending on the situation of the bulk raw material 2 or the tidal difference, the efficiency of the grab bucket 10 is maintained without damage to the ship. Able to carry out good cargo handling.

Further, the landing detector 21 detects that the grab bucket 10 has landed on the bulk material 2,
Even if the brakes of each motor 13, 15 are activated at that point, each wire drum 12, 14 will immediately
does not stop, and the opening/closing wire 8 and the support wire 9 are fed out after landing due to inertia.

In this case, the payout length F (see FIG. 6) of the wire 9 is calculated by the wire payout length calculator 23 via the wire payout length detector 16, and the calculated output is input to the control device 22. The motor 15 is driven by the control device 22 so that the calculated wire payout length after landing becomes a predetermined wire slack length, and the payout length of the wire 9 is adjusted to make the slack amount a predetermined value (wire Feeding length adjustment amount = Standard feeding amount - F).

After the grab bucket 10 lands on the bulk raw material 2, it automatically enters the closing operation (grasping operation), and at the same time, the wire 9 of the calculated length adjustment amount is paid out, and the grab bucket 10 completes the closing operation. During automatic hoisting, the current values of the motors 13 and 15 are input to the gripping amount calculator 24 between D and C, that is, in the _l2 zone, and the gripping amount of the grab bucket 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 gripping amount (or current value) set in advance by the setting device 26, and if the gripping amount is within the control range, the next time the wire 9 will be fed out with the same standard feeding amount. Make adjustments and
If it is out of the control range, next time the standard payout amount will be changed and the payout length of the wire 9 will be 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.

As described above, the gripping amount control method of a grab bucket cart according to the present invention is applicable to a grab bucket truck crane, in which the opening/closing wire of the grab bucket truck is paid out, the wire guide support means in the winding line or the support wire of the grab bucket cart is paid out, and the grab bucket truck is fed out in the winding line. The load detector installed on the wire guide support means detects the load when the wire is fed out, detects the landing of the grab bucket on the bulk raw material surface from the change in the detected load, and determines the point at which this landing is detected. As a standard, the slack length of the support wire is adjusted to control the sinking amount of the grab bucket, and at least one of the motor for driving the open/close wire drum and the motor for driving the support wire drum after grasping the bulk material is adjusted. The detected current at the time of hoisting the grab bucket or the gripping amount of the grab bucket obtained from this detected current is compared with a predetermined target setting value, and based on the comparison result, the next landing detection time is used as the reference point. The slack length of the wire at the time of grasping is determined to adjust the sinking amount of the grab bucket, and the loaded load detector can simply output the change in the applied load of the wire due to landing as a voltage value. Since the landing detector can be obtained as a change in the absolute value of the applied load, the landing detector may be simple and has the advantage that accurate detection can be performed using inexpensive equipment.

[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 output voltage value of the wire load detector 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, by paying out the opening/closing wire of the grab bucket, by feeding out the wire guide support means in the take-up line or by the support wire of the grab bucket, and by the load detector installed on the wire guide support means in the take-up line, The applied load at the time of feeding out the wire is detected, the landing of the grab bucket on the bulk raw material surface is detected from the change in this detected applied load, and the slack length of the support wire is adjusted based on the landing detection point, and the grab bucket is adjusted. In addition to controlling the sinking amount of the bulk material, the current detected by at least one of the motor for driving the open/close wire drum and the motor for driving the support wire drum during hoisting of the grab bucket after grasping the bulk material, or obtained from this detected current. The grab amount of the grab bucket and
Compare with a predetermined target setting value, and based on this comparison result, determine the slack length of the wire at the time of grabbing in the next landing based on the next landing detection time, and adjust the sinking amount of the grab bucket. A method for controlling the gripping amount of a grab bucket.