JPH04262843A - Apparatus for controlling molten metal surface level in continuous caster - Google Patents

Abstract

PURPOSE:To execute molten metal surface level control in a continuous caster executing opening degree adjustment of opening/closing means for adjusting pouring rate with a stepping cylinder driven as pulse in high responsiveness and high accuracy, to make a detecting sensor for opening degree of the opening/closing means unnecessary and to save labor needed to maintenance and adjustment to this. CONSTITUTION:A level control part 1 is constituted with a micro-processor 10, digital signal processor 20 and common bus 30 for these. The micro-processor 10 uses the difference between the detected value of molten metal surface level inputted through analog input/output part 11 and the aimed level, and obtains the necessary opening degree changing quantity for cancelling this difference, and this result is given to the digital signal processor 20 through the common bus 30. The digital signal processor 20 obtains driving direction of the stopping cylinder and the necessary number of the pulse to drive by using this result and outputs through a digital output part 21. Further, this number of pulses is integrated with an integrating counter 22 and the present opening degree for opening/closing means is obtd. with this integrated value.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten metal level control device that operates to maintain a molten metal level in a mold at a predetermined target value during operation of a continuous casting machine.

0002

[Prior Art] Molten metal level control performed during operation of a continuous casting machine stabilizes the cooling and solidification state of molten steel inside the mold, improves the quality of product slabs, and prevents breakouts and other problems during operation. This is extremely important in order to prevent the occurrence of various inconveniences that would force a suspension.

[0003] This level control involves attaching an opening/closing means such as a sliding nozzle or a stopper device to the pouring nozzle that pours the metal into the mold, and also sequentially detects the level of the hot water inside the mold and sets it to a predetermined level. This is done by comparing the amount of molten metal with the target level and adjusting the degree of opening of the opening/closing means to eliminate the deviation between the two and adjusting the amount of molten metal poured into the mold.

Conventionally, the opening/closing means is generally driven by a hydraulic drive system comprising a hydraulic servo cylinder and a servo valve, and in this case, the hot water level control is performed based on a detected value of the hot water level and a target value. The opening command given from the host controller based on the deviation from the level is compared with the current rod position of the servo cylinder, that is, the current opening of the opening/closing means, and the servo valve is operated to eliminate the deviation between the two. This is carried out by controlling the on/off of the servo cylinder and supplying and discharging pressure oil to the servo cylinder.

However, in this configuration, a servo valve with poor heat resistance cannot be placed near the servo cylinder located directly above the mold, so a long hydraulic piping is required to connect the two, and a continuous During operation of the casting machine, positional fluctuations occur between the servo cylinder and the servo valve due to vibrations, so a flexible tube must be used as the hydraulic piping, and the hydraulic pressure supplied from the servo valve is transmitted through the flexible tube. When performing the above-mentioned hot water level control, the hot water level is expanded until the servo cylinder operates in accordance with the operation of the servo valve. There is a time lag between when a fluctuation occurs and when the level is adjusted, and there is a limit to the improvement of responsiveness, making it impossible to meet the recent demand for faster casting speeds. .

In order to solve this problem, in recent years, a hot water level control device has been put into practical use in which the opening degree of the opening/closing means is adjusted by a stepping cylinder instead of a combination of a servo valve and a servo cylinder. The stepping cylinder has a spool driven by a pulse motor attached to a work cylinder that generates the opening/closing force of the opening/closing means, and an actuator that operates so that the spool and the rod of the work cylinder are balanced by hydraulic pressure. This substantially eliminates the need for hydraulic piping, resulting in a significant improvement in responsiveness.

[0007]

[Problems to be Solved by the Invention] By the way, the level control in a continuous casting machine using a stepping cylinder is as follows:
In order to eliminate the deviation between the detected value of the hot water level and the target level, the procedure is to drive the pulse motor that is the drive source of the stepping cylinder, but speed-type control is required to drive the pulse motor. On the other hand, since the deviation has the dimension of position, the configuration of the liquid level control device for performing this control is different from that of a continuous casting machine using a servo valve and a servo cylinder, and conventionally the following 4
The street configuration has been put into practical use.

The first configuration consists of a host controller that determines only the rotational direction of the pulse motor based on the sign of the deviation between the detected value of the hot water level and the target level, and a predetermined amount of normal rotation pulses according to future instructions. Alternatively, a lower controller that outputs reverse pulses is installed in parallel, the output from the lower controller is given to a pulse motor drive circuit, and the pulse motor is driven by the output of the drive circuit. However, in this configuration, the
The drawback is that only off control is performed, and the high responsiveness inherent to the stepping cylinder cannot be utilized at all.

The second configuration is provided with a speed type controller that performs PID calculation using the deviation between the detected value of the hot water level and the target level, and emits a pulse train corresponding to the rotation direction and the magnitude of the deviation. This pulse train is directly output from the pulse motor drive circuit. However, in this configuration, since the pulse train outputted by the controller is a speed-type output, the driving speed of the pulse motor must be limited in order to avoid overrun, and the current opening/closing means Since it is not possible to perform absolute value control while referring to the level, the stepping cylinder's inherent high responsiveness cannot be fully utilized, and automatic start of level control, so-called auto-start, is impossible. .

[0010] The third configuration has a PID similar to the second configuration.
A higher-level controller that performs calculations and emits a pulse width that corresponds to the rotation direction and the magnitude of the deviation, and a lower-level controller that outputs a pulse train corresponding to this pulse width are installed in parallel, and this output is sent to the pulse motor drive circuit. is applied to drive a pulse motor. However, in this configuration, since the pulse motor is driven intermittently, damping occurs in the rotating body of the pulse motor, resulting in step-out, and stable control operation is not compensated for. Similarly, there is a drawback that auto-start is not possible.

[0011] The fourth configuration uses a PID calculation using the deviation between the detected value of the hot water level and the target level to send an opening command to the opening/closing means, that is, a position-type command to a higher-level position-type controller. , has a function of determining the deviation between this opening degree command and the current opening degree, determining the amount of rotation of the pulse motor to eliminate this deviation, and outputting a forward rotation pulse or reverse rotation pulse corresponding to this. A lower speed type controller is installed in parallel, and output pulses from the lower controller are applied to a pulse motor via a drive circuit to operate a stepping cylinder. In this configuration, the first to
Although the difficulty in the third configuration is solved, it requires two controllers, one upper and lower, and the exchange of input and output between them hinders the improvement of responsiveness, and it is also used as feedback information. In order to obtain the current opening degree, for example, it is necessary to attach a position sensor to the rod of the stepping cylinder, and the detection accuracy of this sensor affects the accuracy of the hot water level control, so it is complicated to maintain the detection accuracy. There was a problem in that they were forced to perform extensive maintenance and adjustment work.

The present invention has been made in view of the above circumstances, and it is possible to perform absolute value control using substantially one controller, to make full use of the inherent high responsiveness of the stepping cylinder, and to provide an opening/closing means. An object of the present invention is to provide a liquid level control device for a continuous casting machine that can obtain the current opening degree without using a sensor and reduce maintenance and adjustment work.

[0013]

[Means for Solving the Problems] A liquid level control device for a continuous casting machine according to the present invention is a continuous casting machine having an opening/closing means for adjusting the opening degree of the pouring nozzle into a mold by the operation of a stepping cylinder. Molten metal level control of a continuous casting machine that detects the liquid metal level inside the mold during operation, and controls the amount of metal poured into the mold by driving the stepping cylinder to eliminate the deviation between this and a target level. The apparatus includes a microprocessor that calculates an opening change amount of the opening/closing means based on the deviation and outputs the result, and a microprocessor that uses the output of the microprocessor to calculate the driving direction and the number of driving pulses of the stepping cylinder. a digital signal processor that outputs the signals to the stepping cylinder; a shared bus for both processors; and an integrating means that sequentially integrates the output pulses from the digital signal processor to obtain the current opening degree of the opening/closing means. It is characterized by comprising:

[0014]

[Operation] In the present invention, the opening degree is changed based on the deviation between the detected value of the hot water level and the target level using substantially one controller composed of a microprocessor and a digital signal processor that share a bus. The process of calculating the driving direction of the stepping cylinder and the required number of driving pulses using this is performed all at once, and the output pulses from the digital signal processor are sequentially integrated to perform the auto-start operation. The current opening degree, which is the information necessary for this purpose, can be obtained without providing a dedicated sensor.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to drawings showing embodiments thereof. FIG. 1 is a schematic diagram showing the overall configuration of a molten metal level control device for a continuous casting machine according to the present invention (hereinafter referred to as the device of the present invention).

In the figure, T is a tundish in which molten steel 3 is stored. A cylindrical mold M is arranged below the tundish T at a suitable distance apart, and inside the mold M is an immersion nozzle 4 whose base end is opened at the bottom of the tundish T. has been extended. The molten steel 3 in the tundish T is injected into the mold M through the immersion nozzle 4, cooled by contact with the inner wall of the mold M, and formed into a slab 5 whose outside is covered with a solidified shell 50. , and is continuously pulled out below the mold M. During this drawing, it is further cooled, and after solidification progresses to the inside, it is cut into appropriate dimensions to obtain a product slab that will be used as a material for subsequent processes such as rolling.

In the middle of the immersion nozzle 4, there is a gate plate 60 that opens and closes by sliding in a plane substantially perpendicular to the longitudinal direction of the immersion nozzle 4.
A sliding nozzle 6 is fixedly installed, and the amount of molten metal poured into the mold M can be adjusted by adjusting the opening degree of the sliding nozzle 6. A gate plate 60 of the sliding nozzle 6 is connected to the tip of an output rod of a stepping cylinder 7 integrally equipped with a pulse motor 8. Further, the level of the hot water inside the mold M is detected by a level detector 9 facing the surface of the molten steel 3 remaining in the mold M.

The stepping cylinder 7 is an actuator that incorporates a spool that is positioned according to the rotation of the pulse motor 8, and operates so that the spool and the output rod are balanced by hydraulic pressure. The sliding position of the gate plate 60 connected to the rod, that is, the amount of molten metal poured into the mold M is adjusted according to the operation of the stepping cylinder 7 as the pulse motor 8 rotates.

[0019]The level control of the hot water level in the continuous casting machine configured as described above is carried out by comparing the detection result of the hot water level by the level detector 9 with a preset target level, and
In order to eliminate the deviation between the two, the drive circuit 80 of the pulse motor 8
This is carried out by applying a driving pulse to the driving circuit 80 and opening and closing the sliding nozzle 6 by operating the stepping cylinder 7 in accordance with this. However, in the device of the present invention, the driving pulse to be applied to the driving circuit 80 is determined based on the deviation. The processing up to this point is performed by the operation of the level control section 1.

FIG. 2 is a block diagram showing the hardware configuration of the level control section 1, and FIG. 3 is a block diagram showing the hardware configuration of the level control section 1.
FIG. As shown in these figures, the level control unit 1 includes a microprocessor 10 that calculates the amount of opening change of the sliding nozzle 6 necessary to eliminate the deviation between the detection level and the target level;
The digital signal processor 20 calculates the rotation direction and rotation speed of the pulse motor 8 using this opening change amount, and outputs the forward rotation pulse or reverse rotation pulse necessary for realizing this to the drive circuit 80 of the pulse motor 8. It becomes.

The microprocessor 10 and the digital signal processor 20, as shown in FIG.
It has a shared bus 30 connected via M31,
Data is exchanged between the two at extremely high speed via this shared bus 30. The microprocessor 10 is provided with an analog input/output port 11, a digital input/output port 12, etc., and the digital signal processor 20 is provided with a digital input/output port 21, an integration counter 22, etc. via the shared bus 30. There is.

The deviation between the detected level input to the level control section 1 and the target level is given to the microprocessor 10 via the analog input/output port 11 and the shared bus 30, and the microprocessor 10 uses this to determine the speed. PID calculation of the mold is performed, the opening change amount ΔS (see FIG. 3) required for the sliding nozzle 6 is calculated, and the result is output to the digital signal processor 20 via the shared bus 30.

As shown in FIG. 3, the digital signal processor 20 includes an adder 23, a divider 24, a pulse generator 25, and a counter 26.
The opening degree change amount ΔS outputted from the adder 23 is first given to the adder 23. The adder 23 adds a fraction ΔS″ obtained as described later to the opening change amount ΔS, and obtains the corrected opening change amount ΔS.
' is output to the divider 24. The operating amount of the stepping cylinder 7 obtained by the rotation of the pulse motor 8 according to one pulse output, that is, the opening change amount ΔN of the sliding nozzle 6 is set in the divider 24. , ΔS' given from the adder 23 is divided by this ΔN, and the resulting quotient N is output to the pulse generator 25 and counter 26, and the fraction ΔS'' is output to the adder 23, respectively.

In the above process, the quotient N obtained as a result of the division in the divider 24 includes information on the rotation direction and rotation speed of the pulse motor 8 necessary to obtain the opening change amount ΔS'. , Since this division is performed on the correction value ΔS′ obtained by adding the opening change amount ΔS determined by the microprocessor 10 to the fraction ΔS″ generated by the previous division, the fraction generated at each control opportunity ΔS″
is not truncated, and the opening change amount ΔS, which is a position type command, is reliably converted into a speed type command.

The pulse generator 25 starts its operation in response to the input from the divider 24, and generates a forward rotation pulse or a reverse rotation pulse depending on the sign of N. This pulse is transmitted to the pulse motor 8 via the digital input/output port 21.
The signal is output to the drive circuit 80 and used to drive the pulse motor 8 in rotation. The pulses generated by the pulse generator 25 are also given to the counter 26, which counts the pulses until it reaches the value of N given from the divider 24, and immediately starts generating pulses after counting. The pulse generator 25 generates an off signal to stop the pulse output from the pulse generator 25.

That is, the digital signal processor 20
, the number of pulses corresponding to the absolute value of the opening change amount ΔS given from the microprocessor 10 is generated in the direction corresponding to the positive or negative value to complete one operation, and the output positive The pulse motor 8 is driven by a rotation pulse or a reverse rotation pulse, and the stepping cylinder 7 is driven accordingly.
Through this operation, the opening degree change amount ΔS is realized with high accuracy. At this time, the digital signal processor 2
A series of processes in the digital signal processor 20 and the microprocessor 10 are performed at extremely high speed, and data exchange between the digital signal processor 20 and the microprocessor 10 is also carried out using the shared bus 30 of the two.
Since this is performed at extremely high speed via the stepping cylinder 7, the inherent high responsiveness of the stepping cylinder 7 can be fully utilized, and the accuracy and responsiveness of the hot water level control are greatly improved. This results in
Easily adapts to higher casting speeds.

The output of the counter 26 is also given to an integration counter 22 which stores the initial opening degree of the sliding nozzle 6 at the start of the control operation, and the integration counter 22 receives this stored value from the counter 26. It performs the operation of sequentially updating according to the given count value. The rotational position of the pulse motor 8 correctly corresponds to the number of driving pulses applied to this rotation, and the operating position of the stepping cylinder 7, that is, the opening degree of the sliding nozzle 6, is accurate to the rotational position of the pulse motor 8, which is the driving source. Since they correspond well, the stored value of the integration counter 22 accurately corresponds to the opening degree of the sliding nozzle 6 at each point in time. Therefore, the current opening degree of the sliding nozzle 6 can be obtained with high precision without attaching a position sensor to the rod of the stepping cylinder 7, and this result is used for absolute value control during auto-start.

In this embodiment, a continuous casting machine has been described which is equipped with a sliding nozzle 6 as an opening/closing means for adjusting the amount of molten metal poured into the mold M. It goes without saying that the device of the present invention can also be applied to continuous casting machines equipped with other opening/closing means, such as a stopper device that adjusts the amount of poured metal by raising and lowering a stopper rod arranged at the same time.

[0029]

As described in detail above, the apparatus of the present invention is provided with a level control unit equipped with a microprocessor and a digital signal processor that share a bus, and the former controls the difference between the detected value of the hot water level and the target level. The amount of change in opening is calculated based on this result, and the latter calculates the driving direction of the stepping cylinder and the required number of driving pulses at high speed. At this time, data is exchanged between the two via a shared bus. Since this is done quickly, the high responsiveness of the stepping cylinder that drives the opening/closing means can be fully utilized, and hot water level control with excellent responsiveness and precision can be realized. Furthermore, by installing an integrating means that sequentially integrates the output pulses from the digital signal processor, the current opening degree of the opening/closing means can be obtained without using a dedicated sensor, and the troublesome work for maintenance and adjustment of this sensor can be avoided. The present invention has excellent effects such as enabling auto-start by absolute value control without the need for the automatic start.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the overall configuration of the device of the present invention.

FIG. 2 is a block diagram showing the hardware configuration of a level control section.

FIG. 3 is a block diagram showing the contents of calculations within the level control section.

[Explanation of symbols]

1 Level control section 6 Sliding nozzle 7 Stepping cylinder 8 Pulse motor 10 Microprocessor 20 Digital signal processor 22 Integration counter 23 Adder 24 Divider 25 Pulse generator 30 Shared bus M Mold T Tundish

Claims (1)

[Claims] [Claim 1] When operating a continuous casting machine, which is equipped with an opening/closing means in a nozzle for pouring molten metal into a mold, the opening of which is adjusted by the operation of a stepping cylinder, the level of the molten metal inside the mold is detected, and this and the target level are compared. In a continuous casting machine hot water level control device that controls the amount of molten metal poured into the mold by driving the stepping cylinder in order to eliminate the deviation, the amount of change in the opening degree of the opening/closing means is calculated based on the deviation. , a microprocessor that outputs this result, a digital signal processor that uses the output of the microprocessor to calculate the driving direction and the number of driving pulses of the stepping cylinder, and outputs this to the stepping cylinder, and a digital signal processor that is shared by both processors. A melt level control device for a continuous casting machine, comprising: a bus; and an integrating means for sequentially integrating output pulses from the digital signal processor to obtain the current opening degree of the opening/closing means.