JP2835191B2 - Level control device for mold level in continuous casting machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for maintaining and controlling a metal level in a mold of a continuous casting machine to a target metal level with high accuracy.

[0002]

2. Description of the Related Art Conventionally, a mold level control apparatus in a continuous casting machine has been known, as shown in FIG. 17, for maintaining a mold level in a mold at a target level. ing.

FIG. 17 is a block diagram showing a conventional continuous casting machine equipped with a conventional mold level control device.
In the figure, 51 is a molten steel pot, and a through hole 53a having the same diameter as the molten steel outflow hole 52c of the tundish 52 is provided on the lower surface of the tundish 52 installed below the molten steel pot 51.
Is fixed. A seal plate 54 having a through-hole 54a having the same diameter as the molten steel outflow hole 52c is provided at a position below the plate 53 at a predetermined interval, and a tundish 52 is provided between the plates 53, 54. Is provided with a slide valve 55 provided with a through hole 55a having the same diameter as the molten steel outflow hole 52c.

[0004] The slide valve 55 is a tundish 5
This is for adjusting the amount of molten steel that is injected into the mold 56 from the mold 2 and becomes the cast slab 57. The molten metal level in the mold 56 is maintained at a target molten metal level by a molten metal level control device in a mold described later. By sliding the position of the through hole 55a with respect to the through holes 53a and 54a of the other plates 53 and 54, the opening degree of the through hole 55a is corrected and adjusted.

The structure of a conventional mold level control device in a mold will be described. An upper bracket 52a is fixed to a side surface of a tundish 52, and the upper bracket 52a
, A hydraulic cylinder 61 is swingably mounted.
A lower bracket 52b is fixed to a side surface of the tundish 52 below the upper bracket 52a, and a link 62 is swingably attached to the lower bracket 52b. The tip of the piston rod 61a is connected with a pin. Further, the other end of the link 62 is connected to the slide valve 55 via a connecting rod 63.

Reference numeral 64 denotes a differential transformer for detecting the position (displacement) of the piston rod 61a of the hydraulic cylinder 61, the main body of which is fixed by a support member (not shown) and the like, and the rod-shaped core thereof is fixed. Is moved together with the piston rod 61a.
A voltage signal is output according to the position of “a”.

[0007] Further, reference numeral 65 denotes a level meter of an eddy current type, an electrode following type or the like for detecting the level of the molten metal in the mold 56, 65a denotes an amplifier of the level gauge 65, and 66 denotes a target for setting the level of the molten metal. The target level setting device 67 receives the output of the level meter 65 and the output of the target level setting device 66 via the amplifier 65a as inputs, and calculates the difference between them as PID.
A valve opening command section 68, which is operated by an arithmetic circuit or the like and outputs a value corresponding to the difference between the two outputs, is a cylinder control section 68 comprising a normal directional control valve, a servo amplifier and the like. Receives the output of the valve opening command section 67 and the output of the differential transformer 64 used for positioning control, and sets the level of the molten metal in the mold 56 in accordance with the output of the valve opening command section 67 as the target hot water. This is for controlling the operation of the hydraulic cylinder 61 so as to maintain the surface level.

Next, the operation of the conventional mold level control device in the mold constructed as described above will be described. The amount of molten steel injected into the mold 56 through the slide valve 55 and the amount of withdrawal of the slab 57 are unbalanced. Occurs, and the level total 6
5 and the output of the target level setting unit 66, an output corresponding to the difference between the two outputs is given from the valve opening command unit 67 to the cylinder control unit 68.

The cylinder controller 68 operates the hydraulic cylinder 61 accordingly. For example, when the molten metal level in the mold 56 is higher than the target molten metal level, the piston rod 61a of the hydraulic cylinder 61 is extended, and the slide valve 55 is slid via the link 62 and the connecting rod 63 so that the opening degree is increased. Is adjusted to reduce the amount of molten steel injected into the mold 56.

[0010]

However, the above-described conventional mold level control apparatus in a mold is useful for maintaining and controlling the mold level in the mold to a target mold level. As described above, there is a problem in the control accuracy of the level of the molten metal.

That is, the hydraulic cylinder 61 is operated, and the slide valve 55 is slid through the connecting portions such as the link 62 and the connecting rod 63 to correct the opening thereof. Piston rod 61a of hydraulic cylinder 61 due to mechanical play due to the existing gap
And the sliding amount of the slide valve 55 is displaced, and accurate level control of the molten metal cannot be performed.

In particular, when the sliding direction of the slide valve 55, which is important for controlling the level of the molten metal, is changed, that is, when the operating direction of the hydraulic cylinder 61 is changed, the play of the connecting portion causes a control delay. As a result, the level of the molten metal level becomes large, and as a result, the quality of the cast piece 57 is reduced.

It should be noted that the value of the play of the connecting portion fluctuates from the value before the start of casting due to the high temperature atmosphere during casting, and the slide valve 55, the link 62, the connecting rod 63, etc. The value is different each time it is exchanged, so that it is difficult to grasp the value as a constant value in advance.

The present invention is intended to solve such a problem, and incorporates mechanical play in a control system collectively on-line so that the play can be automatically corrected so that the surface of the molten metal in the mold can be corrected. An object of the present invention is to provide a mold level control device in a continuous caster capable of maintaining a level at an optimum state with high precision over the entire length of casting.

[0015]

In order to achieve the above-mentioned object, in the continuous casting machine according to the present invention, an apparatus for controlling the level of a molten metal in a mold (claim 1) adjusts the amount of molten steel injected from a tundish into the mold. A hydraulic cylinder that adjusts the opening of the slide valve by expanding and contracting a piston rod, a level meter that detects the level of the molten metal in the mold, and a valve that outputs a value corresponding to the deviation between the detection result and the target molten metal level An opening degree command section is provided, and the level of the molten metal in the mold is maintained and controlled at the target level by operating the hydraulic cylinder in accordance with the output of the valve degree instruction section.
Based on the output of the valve opening command section, an output at the time when the output is minimum or maximum is obtained as a first output value, and then the level of the molten metal in the mold is minimized based on the output of the level meter. Alternatively, the output of the valve opening command section at the time when the maximum value is obtained is obtained as a second output value, and the slide valve and the piston rod are determined based on the difference between the first output value and the second output value. And a backlash correction value calculating means for calculating a mechanical backlash existing as a backlash correction value, and a direction in which the hydraulic cylinder is operated is determined based on an output of the valve opening command section to change an operating direction. And a play correction control means for adding the play correction value obtained by the play correction value calculation means to the output of the valve opening command section at that time.

The device according to a second aspect of the present invention includes a hydraulic cylinder, a level gauge, and a valve opening command unit similar to the device of the first aspect, and a position detector for detecting a position of a piston rod. Operating the hydraulic cylinder in accordance with the output of the degree command unit to maintain and control the level of the molten metal in the mold at the target level, wherein the output of the position detector is determined by the level meter and the level meter. A delay circuit for delaying and outputting a time corresponding to the primary delay of the hydraulic cylinder, and a mechanical system existing between the slide valve and the piston rod based on the output of the level meter and the output of the delay circuit. A backlash correction value calculating means for calculating the backlash as a backlash correction value, and a direction for operating the hydraulic cylinder is determined based on an output of the valve opening command section, and the operating direction is changed. The output of the valve opening command of Rutoki is characterized in that a backlash correction control means for adding the backlash correction value obtained by said backlash correction value computing means.

Further, the device according to a third aspect of the present invention includes a hydraulic cylinder, a level gauge, a valve opening command unit and a position detector similar to the device according to the second embodiment, and the device according to the output of the valve opening command unit. The hydraulic cylinder is operated to maintain and control the molten metal level in the mold at the target molten metal level. The movement width of the piston rod is obtained based on the output of the position detector, and then the movement is performed. Based on the width and the current backlash correction value, a backlash correction value calculating means for calculating a mechanical backlash existing between the slide valve and the piston rod, and a direction for operating the hydraulic cylinder, the valve opening command. The play control unit determines the play based on the output of the control unit and adds a play correction value obtained by the play correction value calculating means to an output of the valve opening command unit when the operation direction is changed. It is characterized in that is provided with a door.

[0018]

According to the first aspect of the present invention, the backlash correction value is calculated by paying attention to the control delay between the molten metal level and the output of the hydraulic cylinder opening valve opening command section. In other words, the movement distance (control delay) of the piston rod from the change in the operation direction of the hydraulic cylinder to the actual change in the level of the molten metal level accompanying the change in the operation direction is the slide valve and the piston rod. Attention is paid to the fact that the output is substantially equal to the mechanical backlash existing between the first and second output values at the time when the output of the valve opening command section is minimized or maximized. The difference between the level and the second output value of the valve opening command unit at the time when the level becomes minimum or maximum is obtained, and based on the difference, the mechanical play existing between the slide valve and the piston rod becomes loose. It is calculated as a correction value. In the backlash correction control means, the direction in which the hydraulic cylinder is operated is determined based on the output of the valve opening command section, and the output of the valve opening command section when the operating direction changes is added to the backlash correction value calculation means. Is added to the control system in a lump, and the play is automatically corrected and the slide valve is opened by the expansion and contraction of the piston rod of the hydraulic cylinder. The degree can be corrected with high accuracy.

On the other hand, the hydraulic cylinder is actuated by the output of the valve opening command section to change the level of the molten metal, and there is a time delay until the level of the molten metal is output from the level meter (the level meter and the hydraulic cylinder). In the device according to claim 2 of the present invention, the first-order delay of the level meter and the hydraulic cylinder is compensated by the delay circuit for the piston rod position detected by the position detector. Based on the output of the level meter and the output of the delay circuit, a mechanical backlash between the slide valve and the piston rod is calculated as a backlash correction value by the backlash correction value calculating means. Thereby, the calculation error of the play correction value due to the primary delay can be reduced. And claim 1
In the same manner as in the apparatus described above, the direction in which the hydraulic cylinder is operated is determined based on the output of the valve opening command section, and the output of the valve opening command section when the operation direction changes is adjusted by the play correction value By adding the values, the mechanical play is integrated into the control system collectively on-line, the play is automatically corrected, and the opening and closing of the slide valve is ensured by the expansion and contraction of the piston rod of the hydraulic cylinder. Can be corrected accurately.

Further, in the apparatus according to the third aspect of the present invention, the backlash is corrected by focusing on the piston rod position (cylinder opening) waveform when the backlash correction value in the control is insufficient for the actual backlash. The value is being calculated. That is, in the backlash correction value calculating means, the movement width (amplitude) of the piston rod is obtained based on the output of the position detector.
This is the sum of the current play correction value, the play correction shortage, and the actual effective level control, and the exact mechanical play value (the sum of the current play correction value and the play correction shortage) is the current play correction. It can exist between the value and the movement width. Therefore, based on the movement width and the current play correction value, an appropriate value between the movement width and the current play correction value is calculated as the next play correction value.
In the same manner as in the device of the first aspect, the direction in which the hydraulic cylinder is operated is determined based on the output of the valve opening command section, and the output of the valve opening command section when the operating direction changes is corrected by the backlash correction. By adding the play correction value from the value calculation means, mechanical play is incorporated in the control system collectively online, and the play is automatically corrected, and the slide is caused by the expansion and contraction of the piston rod of the hydraulic cylinder. The opening of the valve can be reliably and accurately corrected.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

First, a mold level control device in a mold according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 shows a continuous casting machine provided with the mold level control device in a mold. In FIG. 1, the continuous casting machine in FIG. 1 has the same configuration as that described in FIG. 17, 1 is a molten steel pot, 2 is a tundish, 3 is a bottom plate, 4 is a seal plate, and 5 is a mold described later. A slide valve whose opening degree of the through hole 5a is adjusted by the internal bath surface level control device, 6 is a mold, and 7 is a cast piece. The plates 3 and 4 sandwiching the slide valve 5 are also formed with through holes 3a and 4a having the same diameter as the through holes 5a so as to communicate with the molten steel outflow holes 2c of the tundish 2. .

As shown in FIG. 1, as a configuration of the mold level control device in the mold, an upper bracket 2a is fixed to the side surface of the tundish 2, and the upper bracket 2a
, A hydraulic cylinder 8 is swingably mounted. A lower bracket 2b is fixed to a side surface of the tundish 2 below the upper bracket 2a, and a link 9 is swingably attached to the lower bracket 2b. The tip of the rod 8a is connected with a pin. Further, the other end of the link 9 is connected to the slide valve 5 via a connecting rod 10.

Reference numeral 11 denotes a differential transformer for detecting the position (displacement) of the piston rod 8a of the hydraulic cylinder 8.
(Position Detector), the main body is fixed to the hydraulic cylinder 8 and the like by a support member (not shown), and the rod-shaped core is moved together with the piston rod 8a.
A voltage signal is output according to the position of a. 12
Is a level meter for detecting the level of the molten metal in the mold 6, and 12a is an amplifier of the level meter 12.

Reference numeral 13 denotes a level meter 12 via an amplifier 12a.
A moving average processing unit for performing a moving average process on the output (level detection result) to remove a secondary vibration component included in the level detection result and outputting an actual level fluctuation component; A target level setting unit 15 for setting is used to calculate a deviation between the output of the level meter 12 and the output of the target level setting unit 14 input via the amplifier 12a and the moving average processing unit 13 by a PID operation circuit or the like. And outputs a value MV corresponding to the difference between the two outputs.

Reference numeral 16 denotes a backlash correction control unit which outputs a valve opening correction signal in accordance with a procedure which will be described later with reference to FIG. a cylinder actuating direction determining unit 16a that determines on the basis of the output MV of backlash correction value G _n to be described later to output MV of the valve opening command unit 15 when determining the change in the operating direction by the cylinder operating direction judgment part 16a And an adder 16b that adds

Reference numeral 17 denotes an online play correction value calculation section which calculates and outputs a play correction value _Gn to the play correction control section 16, and the play correction value calculation section 17 comprises a valve opening command section 1
After the output MV based on the output MV 5 and stored by the output when it becomes minimum (or maximum) as the first output value MV _1, molten metal surface level is minimum (or maximum, based on the output of the level meter 12 ), The valve opening command section 15
The output from the store as a second output value MV _2, the first output value of MV ₁ and on the basis of the difference between the second output value MV _2, is present between the slide valve 5 and the piston rod 8a The mechanical play is calculated as the play correction value _Gn . A detailed calculation procedure in the backlash correction value calculation unit 17 will be described later with reference to FIG.

Reference numeral 19 denotes the moving average processing unit 1 described above.
3, target level setting unit 14, valve opening command unit 1
5, a level controller comprising a backlash correction controller 16 and a backlash correction value calculator 17;
The cylinder controller 23 includes a servo valve 21 and a hydraulic unit 22. The cylinder controller 23 receives an output of the level controller 19 and an output of the differential transformer 11 used for positioning control as inputs, Output of controller 19 (valve opening correction signal after backlash correction)
In order to control the operation of the hydraulic cylinder 8 so that the level of the molten metal in the mold 6 is maintained at the target level.

Next, the operation of the apparatus for controlling the level of the level in the mold according to the first embodiment having the above-described structure will be described.

In this embodiment, as shown in FIG. 3, the molten metal level PV detected by the level meter 12 and the hydraulic cylinder 8
The backlash correction value calculation unit 17 calculates the backlash correction value _Gn by paying attention to the control delay with respect to the output MV of the valve opening command unit 15.

That is, the moving direction of the piston rod 8a
The moving distance (control delay) of the piston rod 8a from the change of the (operating direction of the hydraulic cylinder 8) to the actual change of the level of the molten metal level with the change of the moving direction.
Focuses on that it is almost equal to the mechanical play existing between the slide valve 5 and the piston rod 8a.

Therefore, the play correction value calculating section 17 of this embodiment is used.
, The backlash correction value _Gn is calculated according to the flowchart shown in FIG. In the description of the flowchart, A1 to A5 indicate processing procedure (step) numbers.

When the control is started, the backlash correction value calculation unit 1
7 shows a bath surface level PV obtained by the level meter 12 at every predetermined sampling interval Δt, and a valve opening command unit 1.
5 is read, and it is first determined whether or not the output MV of the valve opening command unit 15 has become minimal (step A1). If the output MV has become minimal (the hydraulic cylinder opening by the time) the degree of slope changes from negative to positive, the output at that time is stored as a first output value MV ₁ (step A2).

Thereafter, it is determined whether or not the bath level PV has become minimum (step A3). If the bath level PV has become minimum (when the gradient of the bath level change changes from negative to positive). in stores the output of the valve opening command section 15 at that time as the second output value MV ₂ (step A4).

In the present embodiment, the difference between the stored first output value MV ₁ and the second output value MV ₂ is regarded as mechanical play existing between the slide valve 5 and the piston rod 8a. It is calculated as the backlash correction value _Gn (step A
5).

Here, the difference between the minimal output value MV ₁ of the valve opening command section 15 and the output value MV ₂ of the valve opening command section 15 when the level of the molten metal level PV is minimal is determined by the play correction value G. Although the _n, in step A5, for example, may be calculated backlash correction value G _n by the following equation. However, in the following equation, G _n-1 is the previous backlash correction value.

[0037]

(Equation 1)

Further, instead of the difference between the minimum output value MV ₁ of the valve opening command section 15, and the output value MV ₂ subsequent melt surface level PV minimum when the valve opening command unit 15, shown in FIG. 3 Thus, the maximum output value MV ₃ of the valve opening command section 15 and
Subsequent valve opening command section 15 at the time of maximum bath level PV
Of the difference between the output value MV _4, it may be used to play the correction value G _n as described above.

As described above, the backlash correction value _Gn calculated by the backlash correction value calculation unit 17 in accordance with the flowchart shown in FIG. 2 is output to the addition unit 16b of the backlash correction control unit 16, and the backlash correction control unit 16 In, the correction control is executed according to the flowchart shown in FIG. In addition,
In the description of the flowchart, B1 to B4 indicate processing procedure (step) numbers.

First, when the control is started, the output change amount ΔMV _n (having a positive or negative sign depending on the direction) from the valve opening command section 15 is read at every predetermined sampling interval (step B1). Then, a currently read output variation .DELTA.MV _n, the sign of the product of the previous change amount .DELTA.MV _n-1, to determine the direction of operating time of the hydraulic cylinder 8 (step B2), the hydraulic cylinder 8 and the previous when actuating the same direction _{(ΔMV n · ΔMV n -1 ≧} 0) , the current output M
The V _n as it is output to the cylinder control unit 23 as a valve opening correction signal (step B3), the flow returns to step B1.

On the other hand, if it is determined in step B2 that the hydraulic cylinder 8 is to be operated in the opposite direction to the previous operation (ΔMV _n · ΔMV _n-1 <0), the input from the backlash correction value calculation unit 17 is performed. Of the current play correction value G _n and the output M
And a V _n are added by the addition unit 16b, and outputs the addition result to the cylinder control unit 23 as a valve opening correction signal
(Step B4), and the process returns to Step B1.

The operation direction of the hydraulic cylinder 8 is determined by the cylinder operation direction determination unit 16a based on the positive / negative determination of ΔMV _n and ΔMV _n-1 described above.

In the cylinder controller 23, the servo amplifier 20 opens and closes the servo valve 21 based on the valve opening correction signal from the level controller 19 and the position information of the piston rod 8a from the differential transformer 11. The operation of the hydraulic cylinder 8 is controlled so that the position of the piston rod 8a becomes a valve opening correction signal, that is, the slide valve 5 has an appropriate opening.

As described above, according to the apparatus for controlling the level of the molten metal in the mold of the present embodiment, in the backlash correction value calculating section 17, the slide valve 5 exists between the slide rod 5 and the piston rod 8a of the hydraulic cylinder 8 for driving the slide valve. mechanical backlash, the minimum output value MV ₁ of the valve opening command unit 15, the output value MV ₂ subsequent melt surface level PV minimum when the valve opening command section 15
Is automatically calculated repeatedly during the level control, and is output to the play control unit 16 as the play correction value _{Gn. When} the operating direction of the hydraulic cylinder 8 changes, the predetermined play correction value is obtained. Since the hydraulic cylinder 8 is operated extra by _Gn , the play is automatically corrected, and the opening of the slide valve 5 is reliably and accurately corrected by the expansion and contraction operation of the piston rod 8a of the hydraulic cylinder 8. .

As a result, the mechanical system play can be integrated into the control system at a time and the play can be automatically corrected, and the level of the molten metal in the mold 6 can be accurately adjusted to the target level over the entire length of the casting. It can be held in.

Next, a second embodiment of the present invention will be described with reference to FIGS. 5 to 9. FIG. 5 shows a continuous casting machine provided with the in-mould level control device. In the configuration diagram, as shown in FIG. 5, the device of this embodiment is also configured almost in the same manner as the device of the first embodiment shown in FIG. 1, but in the device of the second embodiment,
Differential transformer 1 for detecting position X of piston rod 8a
1 is input to the online play correction value calculation section 17A via the delay circuit 24, and the online play correction value calculation section 17A outputs the output of the level meter 12 in accordance with the flowchart shown in FIG. 6 or FIG. Based on the (fluent level PV) and the delay output of the delay circuit 24, the mechanical play existing between the slide valve 5 and the piston rod 8a is calculated as a play correction value _Gn , and the play of the play correction control unit 16 is calculated. This is output to the unit 16b, and the detailed calculation procedure will be described later.

Here, the delay circuit 24 is a differential transformer 1
The output X from 1 is supplied to the level meter 12 and the hydraulic cylinder 8
Is output with a delay of a predetermined time ΔT (see FIGS. 7 and 9) corresponding to the delay of.

In FIG. 5, the same reference numerals as those described above denote the same parts, and a description thereof will be omitted.

The operation of the apparatus for controlling the level of the molten metal in the mold according to the second embodiment having the above-described structure will be described.

Generally, the output MV of the valve opening command section 15
The hydraulic cylinder 8 is actuated to change the molten metal level PV, and a time delay ΔT (a first-order delay of the level gauge 12 and the hydraulic cylinder 8) is caused until the molten metal level PV is output from the level meter 12. Occurs.

In this embodiment, in consideration of such a time delay ΔT, a delay circuit 24 is provided in order to reduce a calculation error caused by the time delay ΔT. From the solid line to the chain line, or from FIG. 9 (b)
As shown in (c), the time delay ΔT is compensated for the position X of the piston rod 8a detected by the differential transformer 11, and the level actually contributed to the molten metal level PV and the control to the molten metal level PV. The position of the piston rod 8a is made to correspond. Then, based on the output PV of the level meter 12 and the output of the delay circuit 24 (the detection position X of the piston rod 8a delayed by ΔT), the play correction value calculating unit 17A detects the presence between the slide valve and the piston rod. The mechanical play is calculated as the play correction value _Gn .

Here, two specific examples will be described as an operation procedure of the backlash correction value _{Gn in} the backlash correction value calculation unit 17A. First, referring to FIGS. An example of the calculation procedure of _n will be described. In the description of the flowchart of FIG.
C8 indicates the number of the processing procedure (step).

The play operation principle in the operation procedure shown in FIGS. 6 and 7 will be described.
As shown in (1), the amount fluctuates due to the imbalance between the amount of molten steel injected into the mold 5 and the amount of withdrawal of the slab 7. And
The amount of molten steel injected changes as the opening of the slide valve 5 is corrected, and the change in the amount of unbalance caused by the change appears as a change in the time change rate dPV / dt of the metal surface level PV. That is, when the opening of the slide valve 5 is actually corrected by the operation of the hydraulic cylinder 8, the time change rate dPV / dt of the molten metal level PV changes. Therefore, as shown in FIGS. 7B and 7C, the mechanical play that exists between the slide valve 5 and the piston rod 8a has a constant time change rate dPV / dt of the molten metal level PV, and can be obtained as the movement amount [Delta] X _n of the piston rod 8a of the piston rod 8a of the hydraulic cylinder 8 is a telescopic operation.

Therefore, as shown in FIG. 6, first, when the control is started, the molten metal level PV obtained by the level meter 12 at every predetermined sampling interval Δt, and the differential transformer 11 through the delay circuit 24 The obtained position after piston compensation of the piston rod 8a is read (step C1).
Then, the current level _Pn and the previous level P
Whether the time rate of change _{dPV / dt = (PV n -PV} n-1) / Δt of the computed molten metal surface level PV is constant is determined based on the V _n-1 (step C2). If the time rate of change dPV / dt of the bath level PV is not constant, step C2 is repeated.

Time change rate dPV / dt of molten metal level PV
Is constant, it is determined whether or not the piston rod 8a is moving based on the previous and current post-delay positions of the piston rod 8a (the chain line in FIG. 7B) (step C).
3). Here, while the piston rod 8a returns to step C2 if not moved, and stores the movement start position X _S of the piston rod 8a (step C4).

Next, it is determined whether or not the time change rate dPV / dt of the molten metal level PV is constant based on the newly read molten metal level PV obtained by the level meter 12 (step C5), and the molten metal level is determined. Time change rate dPV of level PV
/ Dt is constant, that is, the piston rod 8a
There despite being moved, when it is not corrected opening of the slide valve 5 by backlash, stores the moving position X _E of the piston rod 8a newly read (step C6). This step C6 is repeated for each read position of the molten metal level PV and the post-delay position of the piston rod 8a until the time change rate dPV / dt of the molten metal level PV changes, whereby the piston rod 8
The movement position _{XE of a} is sequentially updated.

If it is detected in step C5 that the time change rate dPV / dt of the bath level PV has changed,
That is, when the backlash has been fixed opening of being eliminated slide valve 5 is confirmed, this backlash from the difference between the movement position X _E of the piston rod 8a and the movement start position X _S obtains the value [Delta] X _n (step C6), the flow returns to step C2. Then, an average value K of a predetermined number of play values previously obtained and the present play value ΔX _n is obtained, and this is set as a play correction value G _n , and the adding unit 16b of the play correction control unit 16
(Step C8).

The play average value K is provided to the play correction control section 16 every time it is updated. Further, by performing the operation of obtaining the average value K, the variation of the play value ΔX _n due to the thermal expansion of the slide valve 5, the link 9 and the like and the detection error of the change point of the change rate of the molten metal level PV is reduced. The accuracy can be increased by rounding.

Next, another example of a procedure for calculating the play correction value _Gn in the play correction value calculation unit 17A will be described with reference to FIGS. In the description of the flowchart of FIG.
ＤD5 indicates the number of the processing procedure (step).

As shown in FIGS. 8 and 9A and 9C,
Here, when the control is started, the molten metal level PV obtained by the level meter 12 at every predetermined sampling interval Δt.
And the post-lag compensation position of the piston rod 8a obtained from the differential transformer 11 via the delay circuit 24 is read,
First, it is determined whether or not the molten metal level PV in the mold 6 has been minimized based on the output of the level meter 12 (step D).
1) When the molten metal level PV becomes minimum, the position X '(output of the delay circuit 24) of the piston rod 8a after the delay compensation at that time is stored as the first position _x1n (step D2). ).

Thereafter, it is determined whether or not the molten metal level PV in the mold 6 has reached a maximum based on the output of the level meter 12.
(Step D3), when the molten metal surface level PV becomes maximum, the delay compensation after the position X of the piston rod 8a of the time '(the output of the delay circuit 24) is stored as the second position x _2n ( Step D4).

Then, the difference | x _1n -x _2n | between the stored first position x _1n and second position x _2n is regarded as a mechanical play existing between the slide valve 5 and the piston rod 8a. It is calculated backlash correction value G _n (step D5).

It should be noted that the play correction value G _n obtained in the above-described steps D1 to D5 includes the actual balance correction amount included in the value of the output MV of the valve opening command unit 15; It is desirable that a plurality of backlash correction values are continuously obtained by the above-described procedure, and an average value thereof is used as the backlash correction value.

FIG. 3 shows the difference between the minimal output value MV ₁ of the valve opening command section 15 and the output value MV ₂ of the valve opening command section 15 when the level of the molten metal level PV is minimal thereafter. Thus, the maximum output value MV ₃ of the valve opening command section 15 and
Subsequent valve opening command section 15 at the time of maximum bath level PV
Of the difference between the output value MV _4, it may be used to play the correction value G _n as described above.

As described above, the backlash correction value _Gn calculated by the backlash correction value calculation unit 17A according to the flowchart shown in FIG. 6 or FIG. 8 is output to the addition unit 16b of the backlash correction control unit 16, and this backlash correction is performed. In the control unit 16, the correction control is executed according to the flowchart shown in FIG. 4, just like in the first embodiment.

As described above, according to the mold level control device in the mold of the second embodiment, the same effects as those of the first embodiment can be obtained, and the delay circuit 24 controls the level meter 12 and the hydraulic cylinder 8. Since the backlash correction value _Gn is calculated using the position of the piston rod 8a that compensates for the first-order lag, a calculation error due to the first-order lag can be reduced.

Finally, a third embodiment of the present invention will be described with reference to FIGS. 10 to 16. FIG. 10 shows a continuous casting machine provided with the in-mould level control device. In the configuration diagram, as shown in FIG. 10, the device of the present embodiment is almost the same as the device of the first embodiment shown in FIG. 1, but the device of the third embodiment has a piston rod. A signal from the differential transformer 11 for detecting the position X of 8a is input to the online play correction value calculation section 17B and the play correction value calculation section 17B
Is an initial value setting device for giving an appropriate play correction initial value G ₀ , a reference value m, and a target period T ₁ to be described later.

The backlash correction value calculating section 17B of this embodiment
According to the flowchart shown in FIG. 11, after obtaining the movement width y of the piston rod 8a based on the output of the differential transformer 11 (the molten metal level PV), based on the movement width 4 and the current play correction value _Gn , The mechanical play present between the slide valve 5 and the piston rod 8a is calculated as the next play correction value _{Gn + 1} , and the detailed calculation procedure will be described later.

In FIG. 10, the same reference numerals as those described above denote the same parts, and a description thereof will not be repeated.

The operation of the apparatus for controlling the level of the level in the mold of the third embodiment constructed as described above will be described.

In this embodiment, as shown in FIG. 12, the position (cylinder opening) waveform of the piston rod 8a when the backlash correction value _Gn in the control is insufficient with respect to the actual backlash, The play correction value _Gn is calculated. That is,
In backlash correction value calculation unit 17B, based on the output of the differential transformer 11, but obtains the movement width (amplitude) y of the piston rod 8a, the movement width y, as shown in FIG. 12, the current backlash compensation value G _n and is the sum of the actual water level control active component x _n and backlash correction shortage alpha _n, accurate mechanical backlash value (G
It is obvious that ( _n + α _n ) exists between the current play correction value G _n and the movement width y.

Therefore, the backlash correction value calculation unit 17 of this embodiment
B, the difference β between the movement width y and the current backlash correction value G _{n
Based on n} (= y−G _n ), a flowchart shown in FIG. 11 is used so that an appropriate value between the movement width y and the current play correction value G _n becomes the next play correction value G _{n + 1} . The backlash correction value is calculated in accordance with In the description of the flowchart, E1
E8 indicates the number of the processing procedure (step).

In the play correction value calculating section 17B, an appropriate play correction initial value G ₀ is set in advance by the initial value setting device 18 (step E1), and when the control is started, at every predetermined sampling interval Δt. The molten metal level PV obtained by the level meter 12 and the position X of the piston rod 8a from the differential transformer 11 are read. First, based on the position X of the piston rod 8a, the peak of the position of the piston rod 8a is obtained. The width from the peak to the peak, that is, the movement width y is obtained (step E2).

Then, a difference β _n (= y−G _n ) between the movement width y and the current play correction value G _n is calculated (step E3), and this difference β _n
Is compared with a preset reference value m (step E).
4).

The reference value m is set to a value at the time of a target cycle T _1, which will be described later, or to the piston rod 8 for the effective level control of the molten metal.
This is set empirically in consideration of the amount of movement of a and the like.

Here, according to FIGS. 13 to 16, the oscillation cycle of the piston rod 8a (the output M of the valve opening
It will be described the target period T ₁ of the same) T as the period of V. For example, when the actual mechanical play is 6.0 mm, the fluctuation state of the molten metal level PV when the correction control is performed with the play correction value _{Gn set} to 0, 5.0, 6.0, 7.0 mm. 13 to 16 show the operation command value MV (the position of the piston rod 8a) to the hydraulic cylinder 8 respectively.

When the backlash correction value _Gn is 0, that is, when there is no backlash correction, as shown in FIG. 13, the fluctuation of the molten metal level PV is large, and the backlash correction value _Gn is 5.0, that is, slightly less than the actual backlash. In this case, as shown in FIG. 14, the fluctuation of the molten metal level PV is considerably suppressed, and when the play correction value _Gn is equal to 6.0, that is, equal to the actual play, as shown in FIG.
Fluctuations in the surface level PV are suppressed to almost 0,
The cycle T of the operation command value MV becomes shorter. Further, when the play correction value _Gn is 7.0, that is, slightly more than the actual play, as shown in FIG.
And the cycle T of the operation command value MV becomes extremely short.

When the operation cycle T of the hydraulic cylinder 8 is short,
The change in the operation direction of the hydraulic cylinder 8 is considerably large, and the mechanical parts such as the hydraulic cylinder 8 are likely to be worn, which is not preferable. In the present embodiment, the ideal target period T ₁ is empirically determined from the relationships shown in FIGS. 13 to 16 and the backlash correction value G at the time of such a target period T ₁ is obtained. The reference value m is empirically determined from the relationship between _n and the actual play, and the online play correction value calculation unit 17B
Is set in advance.

In step E4, as a result of comparing β _n with the reference value m set as described above, if β _n > m, the current play correction amount G _n is insufficient and the next play The correction value G _{n + 1} is calculated by the following equation (step E
5).

G _{n + 1} = G _n + k ₁ · β _n where k ₁ is a constant, and about 1/2 is a good value.

On the other hand, if it is determined in step E4 that β _n > m is not satisfied, the vibration cycle T of the piston rod 8a (or the cycle of the output MV of the valve opening command section 15) T and the aforementioned target cycle compared with the T _1, the condition T> T
_It is determined whether or not ₁ is satisfied (step E6). β _n ≦ m
And in the case of T> T _1, as is apparent from the relationship shown in FIGS. 13 to 16, the current backlash compensation amount G _n is considered to have been set to the desired value, the current backlash compensation After the value _Gn is used as the next play correction value _{Gn + 1} without correction (Step E7), the process returns to Step E2. If β _n ≦ m and the condition T> T ₁ is not satisfied, it is considered that the current play correction amount G _n is excessive and β _n has a negative value, and The backlash correction value G _{n + 1} is calculated by the following equation (step E8).

G _{n + 1} = G _n + k ₂ · β _n where k ₂ is a constant, and about 1 is a good value.

As described above, the backlash correction value _Gn calculated by the backlash correction value calculation unit 17B in accordance with the flowchart shown in FIG. 11 is output to the addition unit 16b of the backlash correction control unit 16, and the backlash correction control unit 16B In, the correction control is executed according to the flowchart shown in FIG. 4 just like in the first embodiment.

As described above, the same effect as that of the first embodiment can be obtained by the mold level control device in the mold of the third embodiment.

In each of the above-described embodiments, the differential transformer 11 is used to detect the position (displacement) of the piston rod 8a of the hydraulic cylinder 8, but a potentiometer or the like is used as a position detector. Is also good.

The mold level control device in the mold according to the present invention has a structure in which the hydraulic cylinder 8 is arranged on the bottom side of the tundish 2 or the mold level in the mold is operated by operating the hydraulic cylinder to control the stopper nozzle. Naturally, the present invention can also be applied to a configuration in which the opening degree is adjusted by the opening operation, and the same operation and effect as those of the above embodiment can be obtained.

[0087]

As described in detail above, according to the apparatus for controlling the level of the molten metal in the mold of the present invention (claims 1 to 3), in the backlash correction value calculation section, there exists between the slide valve and the piston rod. The mechanical play is repeatedly and automatically calculated during the level control, and output to the play control unit as a play correction value. When the operating direction of the hydraulic cylinder changes, the hydraulic pressure is increased by the predetermined play correction value. Since the cylinder is operated, mechanical backlash is collectively incorporated into the control system online, and the backlash can be automatically corrected.

Therefore, even when a different tundish is used, optimal play control can be performed, and the play correction value can be periodically updated even when the play is changed due to heat during casting. Can be quickly and accurately maintained over the entire length of the casting in an optimum state with high precision, which greatly contributes to the improvement of slab quality.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a continuous casting machine having a mold level control device in a mold as a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining a procedure of calculating a backlash correction value by a backlash correction value calculating unit of the first embodiment.

FIG. 3 is a graph for explaining a control delay between a molten metal level and a hydraulic cylinder opening.

FIG. 4 is a flowchart illustrating an example of a control procedure performed by a play correction control unit according to the first embodiment.

FIG. 5 is a configuration diagram showing a continuous casting machine having a mold level control device in a mold as a second embodiment of the present invention.

FIG. 6 is a flowchart illustrating an example of a procedure of calculating a play correction value by a play correction value calculating unit according to the second embodiment.

FIG. 7 is a timing chart for explaining the operation of the device of the second embodiment.

FIG. 8 is a flowchart for explaining another example of the procedure of calculating the backlash correction value by the backlash correction value calculation means of the second embodiment.

FIG. 9 is a timing chart for explaining the operation of the device of the second embodiment according to the modification.

FIG. 10 is a configuration diagram showing a continuous casting machine provided with a mold level control device in a mold as a third embodiment of the present invention.

FIG. 11 is a flowchart for explaining a procedure of calculating a backlash correction value by a backlash correction value calculation unit of the third embodiment.

FIG. 12 is a graph showing a piston rod position waveform.

FIG. 13 is a graph showing the level of the molten metal and the operating state of the hydraulic cylinder when the backlash correction value is 0.

FIG. 14 is a graph showing a fluid level and a hydraulic cylinder operating state when the backlash correction value is insufficient.

FIG. 15 is a graph showing the level of the molten metal and the operating state of the hydraulic cylinder when the play correction value is equal to the actual mechanical play.

FIG. 16 is a graph showing the level of the molten metal and the operating state of the hydraulic cylinder when the backlash correction value is excessive.

FIG. 17 is a configuration diagram showing a conventional continuous casting machine provided with a mold level control device in a mold.

[Explanation of symbols]

 Reference Signs List 1 molten steel pot 2 tundish 2a upper bracket 2b lower bracket 2c molten steel outflow hole 3 bottom plate 3a through hole 4 seal plate 4a through hole 5 slide valve 5a through hole 6 mold 7 cast piece 8 hydraulic cylinder 8a piston rod 9 link 10 connecting rod DESCRIPTION OF SYMBOLS 11 Differential transformer 12 Level meter 12a Amplifier 13 Moving average processing unit 14 Target level control unit 15 Valve opening command unit 16 Playback correction control unit 16a Cylinder operation direction determination unit 16b Addition unit 17, 17A, 17B Online play correction value Calculation unit 18 Initial value setting unit 19 Level controller 20 Servo amplifier 21 Servo valve 22 Hydraulic unit 23 Cylinder control unit 24 Delay circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-77757 (JP, A) JP-A-3-57546 (JP, A) JP-A-62-114753 (JP, A) 31053 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) B22D 11/18 B22D 11/16 104

Claims (3)

(57) [Claims] 1. A hydraulic cylinder for adjusting an opening of a slide valve for adjusting an amount of molten steel injected from a tundish into a mold by expanding and contracting a piston rod; A valve opening command section that calculates a deviation between the detection result of the level meter and the target level and outputs a value corresponding to the deviation; and controls the hydraulic cylinder in accordance with an output of the valve opening command section. In the mold level control device in the continuous casting machine for maintaining and controlling the mold level in the mold at the target mold level by operating the valve opening command, the valve opening command is set based on the output of the valve opening command section. After obtaining the output at the time when the output of the part becomes minimum or maximum as the first output value, when the level of the molten metal in the mold becomes minimum or maximum based on the output of the level meter After obtaining the output of the valve opening degree command section as the second output value, the output exists between the slide valve and the piston rod based on the difference between the first output value and the second output value. A backlash correction value calculating means for calculating mechanical backlash as a backlash correction value, and a valve opening when the operating direction of the hydraulic cylinder is determined based on an output of the valve opening command section and the operating direction is changed. An apparatus for controlling a level of a molten metal in a continuous casting machine, comprising: a play correction control means for adding a play correction value obtained by the play correction value calculation means to an output of a command part. 2. A hydraulic cylinder for adjusting an opening of a slide valve for adjusting an amount of molten steel injected from a tundish into a mold by expanding and contracting a piston rod; a position detector for detecting a position of the piston rod; A valve for detecting the level of the molten metal in the mold, and a valve opening command unit for calculating a deviation between the result of detection of the level and the target level and outputting a value corresponding to the deviation; In the mold level control device in a continuous casting machine for maintaining and controlling the mold level in the mold at the target mold level by operating the hydraulic cylinder according to the output of the opening degree command unit, the position detection is performed. A delay circuit for delaying the output of the level meter by the time corresponding to the primary delay of the level meter and the hydraulic cylinder, and outputting the output of the level meter and the delay circuit. Based on the force, a play correction value calculating means for calculating a mechanical play that exists between the slide valve and the piston rod as a play correction value, and a direction in which the hydraulic cylinder is operated by the valve opening command unit. A play correction control means for adding the play correction value obtained by the play correction value calculation means to the output of the valve opening command section when determining based on the output and changing the operation direction is provided. A mold level control device in a mold in a continuous casting machine characterized by the above-mentioned. 3. A hydraulic cylinder for adjusting an opening of a slide valve for adjusting an amount of molten steel injected from a tundish into a mold by expanding and contracting a piston rod; a position detector for detecting a position of the piston rod; A valve for detecting the level of the molten metal in the mold, and a valve opening command unit for calculating a deviation between the result of detection of the level and the target level and outputting a value corresponding to the deviation; In the mold level control device in a continuous casting machine for maintaining and controlling the mold level in the mold at the target mold level by operating the hydraulic cylinder according to the output of the opening degree command unit, the position detection is performed. After obtaining the movement width of the piston rod based on the output of the vessel, the distance between the slide valve and the piston rod is determined based on the movement width and the current play correction value. A backlash correction value calculating means for calculating a mechanical backlash as a backlash correction value, and a valve opening when changing the operating direction by determining a direction in which the hydraulic cylinder is operated based on an output of the valve opening command section. A backlash level control device in a continuous casting machine, comprising: a backlash correction control unit that adds a backlash correction value obtained by the backlash correction value calculation unit to an output of the degree command unit.