JPH02117714A - Method and device for controlling hydraulic lifting gear - Google Patents

Abstract

PURPOSE:To always keep an ascent end point constant by detecting a temperature of hydraulic oil of a hydraulic lifting gear, and quickening or delaying an ascent cart time of an object to be carried in accordance therewith. CONSTITUTION:When a coil comes to a fixed position, that is, a position for intersecting a photoelectric tube 17, its passing is detected. Simultaneously, time is counted up by a counter. It is counted up until time (t) by the counter becomes equal to a reference value T stored in advance. In case of (t)=T, an operation of the counter is ended, and subsequently, an oil temperature is measured. Based on its measured temperature, an operating speed of a piston corresponding to its oil temperature is derived from a map stored in advance, and a time correction value is detected therefrom. Next, after the time to which the time correction time is added, an extractor ascent command is outputted. After an ascent of an extractor is completed, that is, after the coil reaches a shift point, a transfer 15 starts to operate, and also, a branch conveyor 11 starts to operate, and the coil is placed on the branch conveyor 11 and moved in the prescribed direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention generally relates to a device and method for preventing fluctuations in the lifting speed due to changes in viscosity caused by changes in temperature of hydraulic fluid in a hydraulic lifting device.

In particular, the present invention is designed to raise the conveyed object (such as a steel plate) from the main conveyance line when changing the conveyance direction of the conveyed object (steel plate, etc.) while continuing to convey it in a hot-rolling or cold-rolling line for steel plates, etc. Concerning the extractor that is being transported, carry out the extraction while the extractor is still being transported. In other words, the steel plate is extracted, and in particular, a control method that takes into account its temperature compensation and a tractor that gradually loads the steel plate in an oblique direction when viewed from the direction of conveyance.
It will be lifted up.

[Conventional technology]

For example, in a steel plate hot rolling or cold rolling line, a coiled steel plate is conveyed on a conveyor with its cylindrical axis oriented vertically, and the destination is changed depending on the plate thickness, etc. When branching the conveyor line, a hydraulic lifting device called an extractor is used. This extractor is used to slightly lift the steel plate and smoothly transfer it onto the branch line when a steel plate sent in one direction is branched and conveyed, for example, in a direction perpendicular to that direction. In this way, when the steel plate is lifted up by the extractor, it can be transferred to the branch conveyor while the main conveyor remains in operation without stopping it.

When lifting a steel plate with an extractor, generally
[Problem to be Solved by the Invention] With the steel plate placed on the main conveyor, however, in the conventional extractor as described above, changes in viscosity due to temperature changes in the hydraulic fluid of the hydraulic lifting device are I hadn't considered it at all. That is, the viscosity of the hydraulic oil changes depending on the temperature, and as a result, the operating speed of the piston of the hydraulic cylinder changes. In particular, the working environment in hot rolling and cold rolling lines of steel mills is extremely high, and the surrounding temperature changes accordingly. Therefore, temperature changes in the hydraulic oil of the hydraulic lifting device cannot be ignored.

In other words, when the temperature of the hydraulic oil becomes high, the viscosity decreases, so the piston operates at a relatively high speed.On the other hand, when the temperature is low, the viscosity increases, so the operation speed becomes relatively slow.

By the way, in order to determine the start position (timing) of lifting and lowering the steel plate, the extractor uses a sensor such as a phototube to detect that the steel plate has passed a predetermined position, and starts lifting and lowering after a predetermined time from the detection time. ing. In other words, the start time of raising and lowering the steel plate is always a certain number of seconds after the detection time by the phototube. Therefore, on the high temperature side, since the piston moves relatively quickly as described above, the steel plate reaches its raised position relatively quickly, and conversely, on the low temperature side, the time to reach the raised position is delayed. In other words, since the steel plate is being conveyed at a constant speed by the main conveyor, on the high temperature side it reaches the rising position before the original transition point (the point at which the steel plate is brought to the rising position and transferred onto the branch conveyor). Furthermore, on the low temperature side, even if the transition point is reached, the rising position has not yet been reached. In other words, there was a problem in that the extractor lift completion time varied. As a result, the extractor center (corresponding to the transition point) and the coil (f
mj13. ') There was a problem that the center did not match. Due to this discrepancy, the steel plate could not be transferred to the branch conveyor correctly, resulting in a failure in the receiving and the steel plate falling off the conveyor.

This is because changes in the temperature of the hydraulic oil, that is, changes in the operating speed of the piston due to temperature, are not taken into consideration.

FIG. 7 shows the results of actually measuring the time taken to complete the rise of the extractor depending on the temperature of the hydraulic oil. According to this, the rise completion time (measured value) was 3.0.3°7.4.6 (seconds) when the oil temperature was 40"C, 230°C, and 20°C.However, the amount of rise was set to 150M.As can be seen from the results of this experiment, there is a clear difference in the operating speed of the piston due to changes in viscosity due to oil temperature.

[Means to solve the problem]

An object of the present invention is to provide a control method and device that compensates for changes in the lifting speed due to temperature changes as described above, and always brings the transported object to a predetermined raised position regardless of the ambient temperature. That is, the problem to be solved by the present invention is to keep the end point of the lift always constant (transition point) by delaying or speeding up the extractor lift start time depending on the temperature of the hydraulic oil.
The goal is to keep it that way.

In order to achieve the above-mentioned object, according to the present invention, an object being conveyed in one direction is raised by a hydraulic lifting device at a predetermined ascent start position while continuing to be conveyed in the same direction. The structure is characterized in that the temperature of the hydraulic oil in the hydraulic lifting device is detected when the object is brought into position, and the time to start lifting the object is accelerated or delayed accordingly.

Preferably, the temperature of the hydraulic fluid in the hydraulic lifting device is compared with a predetermined lower limit temperature value, and based on the difference, the rising start time of the transported object is delayed, so that the rising start time is controlled in the delay direction (one direction). Direction) only.

The apparatus of the present invention for carrying out this method includes: a detection means for detecting when the conveyed object passes a predetermined detection position; a counting means for counting a predetermined time from the timing detected by the detection means; a comparison means for comparing the timing by the counting means with a preset value stored in advance; a control means for determining the lifting start time of the conveyed object based on the output signal of the comparison means; and a hydraulic fluid for the hydraulic lifting device. The structure is characterized in that it includes a temperature sensor that detects the oil temperature of the engine, and a temperature correction means that corrects the ascent/descent start time based on the temperature value of the temperature sensor.

(Operation) When lifting or lowering the transported object, the temperature of the hydraulic oil in the lifting device is constantly monitored and detected, and the output signal is fed back as a parameter to determine the lifting start time.
The lift start time is shifted forward or backward (slower) in anticipation of temperature changes, and controlled so that the lift completion position is always the same. That is, the basic idea of the present invention is to maintain the end time constant by variably controlling the time to start lifting the conveyed object in accordance with changes in the operating speed of the piston. In this way, changes in the viscosity of the hydraulic fluid due to temperature changes are compensated for.

Further, as described in claim 2, if the expected minimum temperature of the hydraulic fluid is preset in advance and the difference in measured temperature is detected, the rise start time is always increased by an amount commensurate with the temperature difference. Therefore, there is no need to perform control to advance the start time of the rise, which simplifies the control.

Further, according to the device of the present invention, the temperature of the hydraulic oil is detected by the temperature sensor, and the detection signal is fed back to the control unit that determines the timing to start raising/lowering. Therefore, each time the conveyed object comes to the lifting position, the lifting start time is set to compensate for the temperature change of the hydraulic oil at that time.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, we will briefly explain the steel plate extractor, which is the main application target of the present invention (Figure 2.3.4).
.

In FIG. 2, the steel plate that has been subjected to a predetermined rolling process is sent onto the No. 1 conveyor 3 to the left in the figure in a coiled state. The steel plate that has arrived on the turntable 5 is made to go straight or change its direction to the left or right depending on the subsequent processing. Here, consider the steel plate sent to the No. 6.7 conveyor 7.8 on the right (conveyors No. 82 to No. 005 are omitted). The steel plates on the No. 7 conveyor are then sent to the extractor 9, where, depending on the plate thickness, for example, some items are diverted onto the right branch conveyor 11, while others continue straight and are transferred to another conveyor. conveyor 1
3 sent above. In the extractor 9, the steel plate is gradually lifted upward while being sent forward by a conveyor. When the steel plate reaches the uppermost position (raised position), it completely floats up from the conveyor and moves to the right branch conveyor.
Preparations for transferring to the top are completed. In addition, branch conveyor ll
The upward transfer takes place via a transfer 15. Also, during this transfer, the main conveyor (7,
8) remains activated. Therefore, after the passage of the steel plate is detected by the phototube 17 placed along the line of the main conveyor, the steel plate starts to be lifted by the construction tractor 9 after a predetermined period of time has elapsed, and then is brought to the desired lifting position after a further predetermined period of time has elapsed. become.

Figure 3.4 shows an enlarged view of the extractor section. The extractor 9 is basically in the form of a chain conveyor consisting of multiple rows of chains, for example.
The shafts 21 of each row are connected by a chain 23, and the motor M
synchronous rotation. This chain conveyor is entirely supported by a support stand 27 that is pivotally supported by a swing arm 25. The swing arm 25 itself is rotatably supported on a base 31 via a pivot 33 in FIG. 4.

One end of the support base 27 is connected to a piston rod 37 of a hydraulic cylinder 35 fixed to the base 31. As a result, when the hydraulic cylinder 35 extends to the right in FIG. 4, the swing arm 25 rotates clockwise, and the entire extractor (roller conveyor) is lifted upward by an amount corresponding to the arc movement. In this way, the steel plate S (FIG. 3) supported on the extractor 9 is floated above the conveyance level (height level) of the main conveyor (chain conveyor). This upward movement is due to the arc movement along the conveyance direction by the main conveyor, so in Fig. 4, for example, the steel plate S sent on the main conveyor 8 in the direction of the arrow is on the extension line It will be gradually lifted. In other words, the upward movement describes an inclined trajectory when viewed in the direction of conveyance by the main conveyor.

Figure 5.6 shows this inclined trajectory (prior art).

In FIG. 5, the vertical axis indicates the stroke amount H (constant: e.g. 300++ua) of the extractor, and t+
tz and tz are oil temperature 40°C, 130°C, and 520°C, respectively.
The rise completion time (sec) in is shown.

Note that the stroke amount H of the extractor does not necessarily correspond to the steel plate S.
does not match the desired lift amount. Because, in general,
This is because, in its starting position, the extractor is positioned slightly below the transport level of the main conveyor.

As is clear from the figure, and as mentioned above, the higher the oil temperature is, the faster the moving speed of the piston of the hydraulic cylinder 35 (Figure 4) is. 1. It becomes slower in the order of <12<13. Conventionally, as mentioned above, the extractor started lifting after a predetermined time (constant) after the phototube 17 (Fig. 2) detected the passage of the steel plate S, so the result was exactly as shown in Fig. 5. It was exhibiting. FIG. 6 shows this more clearly. In the figure, tl, 2, and t1 are the same as in FIG. t is the time from when the phototube 17 detects the passage of the steel plate S until the extractor starts lifting the steel plate, and is detected by a counter (or timer). In addition, L is the extractor center O (Fig. 3) and the photocell 1.
equal to the distance from 7. Therefore, the target amount of movement in the transport direction from the phototube 17 is equal to L+D/2.

This target movement amount L+D/2 is schematically shown in FIG. 1O.

That is, the distance from point A, where the phototube 17 detects passage of the coil S, to the extractor center O (point B) is L+D. Therefore, the distance from the coil center to the extractor center 0 is L+D. /2 (D is the coil diameter).

In FIG. 6, the vertical axis indicates the conveyance amount of the coil (steel plate) in the conveyance direction, and the target value 10D/2 is indicated by an imaginary line. The horizontal axis indicates time, and the counter counts up simultaneously with the detection by the phototube, and the count is completed after a preset time has elapsed. At the same time as the counter operation is completed, the coil starts to rise by the extractor, and each
Even at 20°C, the target value is reached after 3 seconds, t2 seconds, and t1 seconds. Note that the moving speed of the main conhair is constant.

As is clear from FIG. 6, in the past, the extractor always started to rise after a preset time, regardless of the temperature, and therefore the time to complete the rise varied due to temperature differences. In other words, if we consider the situation when the coil is lifted to a certain height, the transition point (corresponding to the extractor center) has still been reached at high temperatures.
Conversely, at low temperatures, the transition point has already been passed.

FIG. 1 shows the basic concept of the present invention. 6th
This will be explained in comparison with the diagram.

In Fig. 6, the extractor rise start time was always constant, which caused the problem that the rise completion time varied, so in the present invention, the extractor rise start time is changed to the temperature as shown in Fig. 1. The differences were made accordingly. That is, in the present invention, t+, tz, tm
In order to align the terminal point of the signal to the target value L+D/2, the waiting time from the time of detection by the phototube is made different. These waiting times are represented in FIG. 1 by tm, Lb%tc (L,>tb>tc). Blockage, extractor rise start time staggered. It should be noted that the time when the extractor starts lifting as referred to herein means the time when the extractor starts lifting the steel plate, and does not necessarily mean the time when the extractor itself starts lifting. That is, as mentioned above, since the starting position of the extractor is often located below the conveying level of the main conveyor, the extractor has some play.

In the control method of the present invention, the operating speed of the piston at a reference temperature is determined, the operating speed of the piston is determined based on the difference between the measured temperature and the reference temperature, and the piston operating start time (rise start time) is determined from that value. time) can be found. In practice, the relationship between the temperature of the hydraulic oil and the operating speed of the piston may be determined from the relationship shown in FIG. 7, for example, and stored in the memory as a map.

In addition, as the above reference temperature, the lowest expected oil temperature,
For example, if O'C is selected, the measured temperature value will always be higher than this reference temperature value, so it is only necessary to control in the direction of delaying the rise start time, and the control is simplified as there is no need to control in the direction of speeding it up. become.

The control J process of the present invention will be described below with reference to FIG. 8.9.

In FIG. 8, when the coil is in a fixed position, ie, in a position where it crosses the phototube 17 (FIG. 2) (step 801), its passage is detected in step 803. At the same time, the counter increments the time (step 80).
5). The time counted by the counter is counted up until it becomes equal to the reference value T stored in advance in step 807. Note that this reference value T may be, for example, tc in FIG. 1. When tmT is reached in step 807, the counter operation ends (step 809), and then in step 811
The oil temperature is measured at Based on the measured oil temperature,
In step 813, for example, the operating speed of the piston corresponding to the oil temperature is determined from a map stored in advance (step 813), and then the time correction value (tb in Fig. 1) is determined.
(Lc, t, "-tc, etc.) (which can also be easily obtained by using a map, for example), and then in step 8I5, an extractor raising command is issued after a period of time in which the above-mentioned time correction value has been added. Finally, in step 817
At , the extractor completes its lift. Note that completion of the extractor's ascent can be easily detected by, for example, a limit switch (not shown).

After the extractor has been raised, that is, after the coil has reached the transition point, the transfer 15 (FIG. 2) starts operating, and the branching conveyor 11 starts operating, and the coil is placed on the branching conveyor 11 and moved in a predetermined direction. Moving. Incidentally, the branch conhair 11 is connected from the extractor via the transfer 15.
How to move the coil upward is the same as in the prior art, and is not directly related to the subject matter of the present invention, so a description thereof will be omitted.

FIG. 9 shows a specific embodiment of the present invention, in which an elevating cylinder 71 of the extractor 9 is connected to a hydraulic oil tank 75 via an elevating solenoid valve 73. still,
The hydraulic circuit of the hydraulic cylinder 71 itself is not directly related to the present invention, so a description thereof will be omitted. An oil temperature gauge 81 is provided in the tank 75, and the measured value is sent to a control device (computer) 83.
sent to. An example of the control process of the control device 83 is the eighth
This is as explained above using the flowchart shown in the figure.

[Effects of the Invention] As described above, according to the present invention, even if the operating speed of the piston fluctuates due to changes in viscosity depending on the temperature of hydraulic oil in a hydraulic lifting device, the fluctuation can be taken into account. Since the piston operation time is controlled, stable piston operation can be obtained regardless of temperature changes.

In particular, when the present invention is used in an extractor, by changing the time when the object to be lifted starts to rise according to the temperature of the hydraulic oil, the time to complete the rise can be made to match, and as a result, the object to be transported can always be kept at a constant level. It can be uniquely brought to the position.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the temperature correction state at the start time of the rise of an extractor according to an embodiment of the present invention, FIG. 2 is a plan view showing the flow direction of a steel plate rolling line to which the present invention can be applied, and FIG. Figure 3 is an enlarged plan view of the main part of the extractor shown in Figure 2, Figure 4 is a cross-sectional view taken along line I-C IV in Figure 3, and Figures 5 and 6 are the completion of lifting using the conventional method. FIG. 7 is a diagram showing the relationship between the time to complete the rise of the extractor and the oil temperature. FIG. 8 is a flowchart showing an embodiment of the control method according to the present invention. FIG. 1 is an illustrative block diagram showing essential parts of an embodiment of the present invention.
Figure O is an illustrative plan view for explaining the target movement amount of the transported object. 9...Extractor, 17...Phototube, 83...
·Control device.

Claims (1)

[Scope of Claims] 1) When lifting an object being conveyed in one direction to a predetermined lifting position by using a hydraulic lifting device at a predetermined lifting start position while continuing to carry it in the same direction, hydraulic lifting is carried out. A method for controlling a hydraulic lifting device, characterized by detecting the temperature of hydraulic oil in the device, and accelerating or delaying the start time of lifting of a conveyed object in accordance with the temperature. 2) When lifting an object being transported in one direction to a predetermined lifting start position by a hydraulic lifting device while continuing to transport it in the same direction, the temperature of the hydraulic fluid in the hydraulic lifting device 1. A method for controlling a hydraulic lifting device, comprising: detecting the temperature, comparing the temperature with a predetermined lower limit temperature value, and delaying the start time of lifting of a conveyed object based on the difference. 3) In a hydraulic lifting device that lifts an object being conveyed in one direction to a predetermined rising position while continuing to convey it in the same direction, the object to be conveyed reaches a predetermined detection position. a detection means for detecting passing; a counting means for counting a predetermined time from the timing detected by the detection means; and a comparison means for comparing the timing by the counting means with a preset value stored in advance;
a control means for determining the time to start raising and lowering the conveyed object based on the output signal of the comparison means; a temperature sensor for detecting the temperature of the hydraulic oil of the hydraulic lifting device; A control device for a hydraulic lifting device, comprising: temperature correction means for correcting the above-mentioned lifting/lowering start time.