JPS6131033B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic operating device for a rope-suspended crane.

Manually operated cranes use a wound induction motor, and its control method uses a resistance control method for the secondary winding.

On the other hand, self-driving cranes that have recently been put into practical use, especially those that are suspended from ropes and require steady rests, use tachometers to increase the accuracy of speed control. A thyristor control method is usually used in which the primary voltage is controlled by feeding back the actual speed and comparing it with the command speed.

Needless to say, investment costs and investment effects are compared at the time of crane automation implementation planning, and the primary voltage thyristor control method has a lower cost than the secondary resistance control method. The more thyristor devices are added, the more expensive it becomes, and the difference can amount to tens of percent of the total investment cost.
In many cases, the implementation plan itself does not come to fruition.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, an object of the present invention is to provide an inexpensive automatic operation device using secondary resistance control when automatically operating a crane. In order to automatically operate a rope-suspended crane as mentioned above, it is necessary to take measures to prevent the suspended load from swinging, but the methods most commonly used to date have been based on physical and mathematical techniques. In this method, a speed pattern is determined so that there is no wobbling at the end of the movement, and the traveling speed of the crane is controlled so that the crane moves according to this speed pattern. (References: "Automation of ore unloader" Machinery Research Vol. 23 No. 1 (1971),
(Kenichi Yoshimoto) In such a system, the accuracy of speed control is most important, but unless extremely accurate speed control is performed, fluctuations will occur due to the difference between the target speed pattern and the actual speed. The actual speed feedback type thyristor primary voltage control device, which has good speed control accuracy, is used as described above.

This eliminates the use of expensive thyristor control devices.
When speed control is performed using the cheapest secondary resistance control method, the causes of reduced speed control accuracy are (1) changes in oil temperature in the reducer that engages the motor output with the power wheels; Changes in acceleration/deceleration due to accompanying changes in frictional force, (2) Traveling due to the running rail gradient distribution,
This is a variation in acceleration/deceleration in both traverse directions, and even if feedback control is performed using a tachometer, the number of control stages is too coarse, making it impossible to achieve an actual speed pattern as precise as in the case of thyristor control.

Now, the inventor has learned how to operate a manually operated crane and has confirmed the following operating techniques, which will be explained first.

(i) Acceleration/deceleration pattern that does not cause deflection Acceleration When the hanging rope is not swinging in both traveling and traversing, or when the hanging rope is swinging in the direction of travel and is in a vertical position as shown in Figure 1. , be sure to raise the notch by one notch. (The same applies during slight tremors).

When you want to drive at high speed, increase the speed one notch at a time as shown in Figure 2 at each timing explained in Figure 1.

If there is a rampant empty load, even just one notch will cause a runout, so it will be necessary to "catch up" as described below.

B. Deceleration Cut the notch just the coasting distance before the stopping point. When you're near the stopping point, apply the brakes if you think you've gone too far.

If it seems like it will stop in front of you, increase the speed a little by "driving up" as described below.

It is preferable to decelerate only by coasting. It's best to use the brakes only when you think you're going too far or when you want to stop shaking. This is because applying the brakes causes runout and wear.

The above-mentioned coasting distance varies greatly depending on the oil temperature of the reducer and the like. Between the start of use in the morning and the evening, the coasting distance changes by about 1m when driving and about 0.3m when traversing.

Another factor that varies the coasting distance is how the slope is applied. When tested with a speed feedback thyristor primary voltage controlled system on a running girder on a certain slope, the running distance was 0.5 m and the traversing distance was 0.2 m.
It is known that there is a difference in the degree of deceleration and the distance of deceleration in the opposite direction. If there is no speed feedback,
Naturally, it is predicted that this number will increase even further.

C. Comparison and correlation between traveling and traversing The terms traveling and traversing have already been used in the above explanation, but traveling of a crane refers to the movement of a crane on the rails laid on the traveling girders provided on both sides of the operating range. Traversing means that the girder moves astride, and traversing means that a club equipped with a hoisting machine mounted on the girder and a traversing electric motor moves on a rail laid on the girder. .

Since the weight (that is, inertia) is greater in traveling than in traversing, the response is slower.

Therefore, if you want to operate both running and traversing at the same time, you should first operate the running, wait until the response begins, and then start the traversing operation.

For the same reason, the amount of operation during "driving" or "stopping", which will be described later, will not be effective unless the amount of operation is larger in the traveling direction than in the traversing direction.

When the girder travels and the club on the girder travels sideways, if the combined traveling direction of the club is a straight line as shown in Figure 3, no swing will occur due to the mutual relationship between the traveling and traveling. , as shown in Figure 4, if you draw even a small arc, vibration will occur due to centrifugal force.

(ii) Steady rest method (when stopped) A. When the maximum sway is above the destination When the sway reaches its maximum as shown in Figure 5,
A one-notch inching operation is performed by the amount of operation (jogging time) that moves the club to the destination.

B. When the center of runout is above the destination At the same timing as in the previous section, as shown in Figure 6, perform two half-length one-notch increments at half-period intervals. In the operations of FIGS. 6 and 7, the operation direction may be reversed, the operation amount may be the same, and the order may be either.

C. When the destination is outside the deflection range, or is within the deflection range but not at the center of the deflection, adjust the amount of operation and perform the inching operation several times at the same timing as in the previous item (a) and the previous item (a).

(iii) Drive-in method This method is used when the travel distance is greater than the inching distance and smaller than the distance to extend the notch, when steadying the notch during travel, when stopping at a certain position that can accommodate fluctuations in coasting distance, etc. used.

The more you want to increase the speed, the larger the swing width,
At the positions shown in FIGS. 8 and 9, the amount of operation (notch inching time) is increased.

Also, start coasting before stopping at a fixed position by coasting, reduce the speed to a very low speed (with a stop along the way), and maintain the coasting force (speed) until you reach the destination, as shown in Figure 10. The above can be achieved by "catching up" each time the vehicle is about to fall, recovering speed, and causing it to lose inertia (speed) at its destination.

As explained above about crane operating techniques, if such operating techniques are programmed, and output information from state detection equipment such as swing angle detectors is incorporated into the control system, and the crane is operated according to the program, the winding By controlling the crane's travel and traverse movement by controlling the secondary resistance of the induction motor, it is possible to operate over any distance and stop at a fixed position without swinging the rope. By taking into account changes in acceleration distance, coasting distance, and (2) differences in deceleration distance due to slope as fluctuation factors, it is possible to implement automatic operation without load swing when stopped, as described later.

To deal with the oil temperature change mentioned above, for example, it is possible to measure the oil temperature and program it to change the acceleration end time and coasting start distance accordingly. Since the inclination of the running girder on which the running rail is installed is known in advance for each girder as shown in FIG. 11, it is sufficient to correct the deceleration distance for both traveling and traversing for each running girder.

Shaking occurs in most cases when operating in two or more of the three directions (travel, traverse, and up and down winding) at the same time, mainly due to centrifugal force and simultaneous winding up and down. Unless this is stopped, it will not be possible to achieve cycle times comparable to manual operation by skilled operators.

In this way, the two items of cycle time and steady rest positioning accuracy are determined at each site (machine and suspended load).
Although it differs depending on the type, it is fully expected that the driving pattern in manual driving will also differ accordingly.

If we look at this from a pure technical perspective, the limit at which runout begins to occur is thought to be determined by nonlinear parts such as friction and torsion, and even if runout occurs due to sudden operation, it is difficult to stop the runout from reaching the stopping position. There may be cases where it would be advantageous in terms of cycle time to eliminate the runout.

Therefore, when implementing automated driving, the driving pattern (sequence) should be determined based on the best driving pattern of experienced drivers.

As already explained, it is necessary to operate the steady rest automatically at the same timing and using the same method as manual operation. In other words, considering the isochronism of the pendulum, even if there is a fluctuation in deceleration, it is thought that it will not affect the phase (time) relationship between the residual swing period and the residual swing phase from the time point when deceleration starts, so manual operation is not recommended. It is thought that this can be dealt with by changing the number of steady rest (driving) operations according to changes in deceleration distance in the standard operation pattern. In FIG. 12, (1) shows the speed pattern when the deceleration is large, and (2) shows the speed pattern when the deceleration is small and the corresponding number of driving operations. However, in such a unique driving operation, the sway width necessarily changes due to changes in acceleration/deceleration, and strict steady rest cannot be expected. Therefore, the amount of steady rest operation (notching time) must be changed in accordance with changes in the swing width. In other words, if the swing width and phase of a suspended load can be detected accurately to a certain extent (to the same degree as the human eye), it will be possible to perform the same steady rest operations during running and stopping during manual operation. That's what it means. Conventionally, there is no practical device that can detect the swing width and phase of this suspended load.

Until now, various types of detectors have been used as rope-suspended automatic operation detectors, one example of which is shown in FIG. In the figure, 11 is a winding drum, 12 is a movable pulley, 13 is a hook, 14 is an equalizer sheave, 15 is a hanging rope, and a detector 16 is attached to the hanging rope 15. When the hanging rope 15 swings from side to side in the figure, such a detector 16 exhibits a waveform in which a high-frequency noise signal is added to the swing represented by the dotted line as shown in FIG. 14. If this high frequency noise is not removed, it cannot be used as a control signal, but attempting to remove it will in principle result in a time delay. The rope is subject to tensile loads due to the hanging equipment and the amount of hanging load, but it is susceptible to vibration in the lateral direction.

The high frequency waves shown in FIG. 14 are due to vibrations of the rope that are constantly occurring due to hoisting and lowering, as well as impacts from rail joints during running and traversing. Therefore, in this method of determining the runout in the middle of the rope, high frequency components are inevitably mixed in.

Therefore, in the present invention, the rotation angle measuring device engaged with the movable pulley and the rotation angle measuring device engaged with the equalizer sheave detect the deflection angle and deflection phase in orthogonal directions, respectively. The above-mentioned steady rest control is performed.

FIG. 15 shows an example of a movable pulley used in the present invention. The swing of the suspended load is always accompanied by the rotation of the movable pulley 12, and the direction of the swing of the main axis of the hook, which is the reference line for detecting the rotation angle, is opposite to the direction of rotation of the movable pulley, and as a result, it works differentially. The difference between the two is obtained as the detected angle, and the swing angle of the suspended load can be detected with high sensitivity, and at the same time, its phase can also be known. The movable pulley and the hook are loaded with a hanging device and a hanging device load, and their inertial force can prevent the intrusion of high-frequency noise components as in the case of detecting the swinging of the rope described above.

The deflection angle measuring device to be engaged with the movable pulley may be selected from among the existing rotation angle measuring devices 17, such as the Selsin motor, optically encoded rotation angle measuring device, etc., depending on size, weight, price, etc. good.

In this type of system, when winding and lowering operations are performed, a DC component as shown by the broken line is naturally added as shown in Figure 16, but such DC component can be removed by either hardware processing or software processing. It is of a nature that can be easily removed by

Further, the deflection angle and phase in the direction perpendicular to the movable pulley can be measured by engaging the rotation angle measuring device with the rotation shaft of the equalizer sheave 14, as illustrated in FIG.

As described above, the deflection angle and the momentary phase angle can be directly measured.

Furthermore, as another method, the deflection angle and phase can be detected by the following method. This is the trolley for the equalizer sheave and its mounting hardware. By attaching a rotation angle measuring device to the mounting shaft to the frame, the deflection angle and deflection phase in the direction perpendicular to traveling and traversing are detected. By using this method, the steady rest control described above is performed.

As shown in FIG. 18, the equalizer sheave 14 has a structure that moves according to the swing of the rope, and the swing of the suspended load always changes the angle of the equalizer sheave 14. That is, a rotation angle measuring device may be attached to the shaft of the equalizer sheave. The figure shows an example in which a rotation angle measuring device 18 attached to the rotating shaft of the equalizer sheave 14 detects the deflection angle in the traveling direction, and a rotation angle measuring device 19 detects the deflection angle in the transverse direction.

Therefore, as mentioned above, by controlling the secondary resistance of the wound induction motor for driving the crane, the amount of steady resting or pushing operation corresponding to the swing width is performed when a specific phase angle is detected, thereby sufficiently reducing the swing. Automatic operation of cranes can be achieved.

In the above-mentioned section, explanation regarding the use of a computer has been omitted, but this point can naturally be accomplished by those skilled in the art in the same manner as when creating a normal program.

[Brief explanation of the drawing]

1 to 10 are explanatory views of the operation of the crane. FIG. 11 is an explanatory diagram of the inclination of the running girder. FIG. 12 shows the states when the deceleration is large and small, and the inching relative to this. FIG. 13 shows an example of a conventional deflection angle detector. FIG. 14 shows a waveform detected by the detector of FIG. 13. Figure 15,
FIGS. 17 and 18 show an example of mounting a rotation angle measuring device used in the present invention. FIG. 16 is a functional explanatory diagram of the rotation angle measuring device shown in FIG. 15. 1... Running girder, 11... Winding drum, 12... Moving pulley, 13
... Hook, 14... Equalizer sheave, 15... Hanging rope, 16... Detector, 17, 18, 19... Rotation angle measuring device.

Claims (1)

[Claims] 1. As a means for measuring the swing angle and phase angle of the suspended load, a rotation angle measuring device is engaged with the movable pulley that holds the hanging rope and the rotating shaft of the equalizer sheave in a direction perpendicular to the movable pulley, respectively, to measure the rotation angle. It is characterized by the use of a secondary resistance-controlled wound induction motor for the girder carrying the suspended load, the running of the club, and the traversing, according to the driving pattern to perform steady resting or pushing operations with the amount of operation corresponding to the sway width from the measuring device. Rope-suspended crane automatic operation device.