KR19990043752A - Automatic control method of molten steel in continuous casting machine mold - Google Patents

Abstract

The present invention detects the weight change of the molten steel in the ladle and tundish over time to detect the amount of molten steel flowing into the mold to control the moving position of the stopper to automatically control the molten steel in the mold molten steel in the mold A method for automatically controlling the amount of liquid, comprising: a process of sensing the weight change of the molten steel in a ladle and the weight change of the molten steel in a tundish over time, and the amount of molten steel flowing into the mold through the immersion nozzle using the detected weight change of the molten steel. And a step of dynamically controlling the position of the stopper so that the hot water surface in the mold can be filled to the casting start position within a predetermined time.

Description

Automatic control method of molten steel in continuous casting machine mold

The present invention relates to a control method of a continuous casting machine, and in particular, to detect the amount of molten steel in the ladle and tundish over time to detect the amount of molten steel flowing into the mold to control the position of the stopper to control the amount of molten steel in the mold The present invention relates to an automatic control method of molten steel in a continuous casting machine mold for automatic control.

The structure of a typical continuous casting machine is composed of a ladle (2), tundish (5), mold 12 as shown in FIG. Initially, the molten steel 1 in the ladle 2 is transferred to the tundish 5, in which the molten steel is poured into the mold 12 through the immersion nozzle 10. When the molten steel is transferred from the tundish 5 to the mold 12, the amount of molten steel flowing into the mold 12 is adjusted by adjusting the inlet area of the immersion nozzle by adjusting the vertical position of the stopper 6.

Starting work of the casting machine to start the continuous casting process consists of two steps: filling the inside of the mold with molten steel and starting the continuous casting process. After the start of casting, the stopper is controlled by an automatic control algorithm that keeps the molten steel at a constant height in the mold.

In the process of filling the inside of the mold with molten steel, the operator intervenes to control the amount of molten steel flowing into the mold 12 using the operating lever 9 to open and close the stopper 6. Then, when the molten steel is filled in the mold up to a previously planned height, an algorithm for automatically controlling the molten steel level in the mold is started.

As an example of the automation for filling the molten steel in the mold as described above, the moving distance and the stop time of the stopper are composed of a static table so that the mold filling step at the start of casting depends on the vertical movement distance and the stopping time of the stopper stored in the static table. The same method is used to always operate the same, but it does not operate dynamically to meet the various casting conditions, and the problem is caused by not considering factors such as clogging of the immersion nozzle.

The present invention was devised in view of the above-described problems of the prior art, and by detecting the amount of change in the weight of molten steel in the ladle and tundish over time to detect the amount of molten steel flowing into the mold to control the movement position of the stopper in the mold. An object of the present invention is to provide a method for automatically controlling molten steel in a continuous casting machine mold for automatically controlling molten steel.

1 is a conceptual block diagram for a continuous casting operation of a typical player;

2 is a view showing the dimensions of the molten steel filled in the mold,

3 is a view for explaining a casting start state by the height of the mold and the molten steel in the mold according to the method of the present invention,

4 is a diagram illustrating a method for controlling the height of molten steel in a mold by the position of the stopper in accordance with the method of the present invention.

*** Explanation of symbols for main parts of drawing ***

1: molten steel 2: ladle

3: exit hole 4: ladle load measuring device

5: tundish 6: stopper

7: connecting rod 8: driving device

9: hand operated lever 10: immersion nozzle

11: tundish load measuring device 12: mold

13: γ sensor 14: cast

15 roll 16 measurement and control device

17 dummy bar 18 gamma sensor measurement area

Automatic control method of molten steel in the continuous casting machine mold according to the present invention for achieving the above object, the process of detecting the weight change of the molten steel in the ladle and the molten steel in the tundish over time, and the weight change amount of the detected molten steel Calculating the amount of molten steel flowing into the mold through the immersion nozzle and dynamically controlling the position of the stopper so that the hot water in the mold can be filled to the casting start position within a predetermined time period. do.

The stopper may smoothly flow the molten steel by reciprocating up and down largely when the amount of molten steel flowing into the mold is reduced due to the blockage of the immersion nozzle.

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

The present invention provides two weight sensors for measuring the weight of molten steel in the ladle 2 and the tundish 5, and an A / D converter and A for converting the signals detected by the two weight sensors into digital values. It is configured to include a control device for calculating the amount of molten steel flowing into the mold by using the / D converted detection signal and to control the operation of the stopper.

Over time, the amount of molten steel flowing from the ladle 2 through the tundish 5 into the mold 12 is the total amount of molten steel in the ladle, molten steel in the tundish, and molten steel in the mold during the mold filling process time. It can be calculated from the fact that the quantity is constant. The amount of molten steel in the mold 12 at any time t is the amount of molten steel remaining in the current ladle and the amount of molten steel in the tundish 5 from the total molten steel L (0) contained in the initial ladle 2. Subtracted amount.

Therefore, the amount of molten steel present in the mold at time t of the mold filling process time can be calculated by Equation 1 below.

[Equation 1]

M (t) = L (0) -L (t) -T (t)

Here, M (0) = 0, T (0) = 0, and M (0) = 0. M (0), T (0) and M (0) are the first molten steel contained in the mold 12, the tundish 5 and the ladle, respectively, M (t), T (t) and M (t). Is the amount of molten steel at time t. Each quantity is in mass units (kg). Initially, there are no molten steel in the mold and tundish, and only the ladle 2 contains molten steel.

By calculating the amount of molten steel flowing into the mold 12, the hot water surface of the molten steel in the mold can be calculated. As shown in Fig. 2, when the width inside the mold is W, the length is D, and the height is H, the total volume inside the mold is WHD. At this time, if the height from the bottom of the hot water surface filled in the mold with molten steel at any time point t is h (t), the height h (t) of the molten steel can be calculated by the following [Equation 2].

[Formula 2]

Here, h (t) is the height of the molten steel in the mold at the time point t, and M (t) is the amount of molten steel existing inside the mold at this time. ρ is the density of iron (Fe) of 7.8 × 10 ³ kg / cm ³ .

As shown in FIG. 3, the filling of the mold with molten steel begins with pouring molten steel after closing the outlet of the mold 12 with a dummy bar 17. When the molten steel in the mold gradually fills and the level of the molten steel reaches the HS position, the dummy bar 17 is pulled and the casting operation is started. By operating the sensor to monitor the level of molten steel with the start of casting automatically detects the level of molten steel and automatically controls the stopper 6 to maintain the level of molten steel within the appropriate range of the γ sensor measurement area (18).

While filling the mold, the amount of molten steel flowing into the mold during the unit time is continuously monitored. If the amount of molten steel flowing into the mold during the specific unit time Δt is less than the predetermined reference amount ML, the stopper 6 is reciprocated up and down to promote the flow of the molten steel. After this stopper reciprocating motion, the amount of molten steel flowing into the mold is monitored, and if it is smaller than the reference amount per unit time, the reciprocation of the stopper is repeated.

4 shows a view of the amount of molten steel in the mold and the position of the stopper. At time T0 the molten steel begins to flow into the mold. The NS area is a normal area and is an abnormal area in which the amount of molten steel flowing into the mold per unit time does not exceed the lower limit. In this region, the stopper reciprocates. When the height of the molten steel in the mold reaches within the height measurement range 18 using the gamma line, the position of the stopper moves to the casting start position, and casting starts when the height of the molten steel reaches the preset casting start position.

In other words, the molten steel contained in the ladle is initially transferred to the tundish for the continuous casting, and the tundish supplies the molten steel to the mold through the immersion nozzle. The amount of molten steel supplied to the mold through the immersion nozzle in the tundish is adjusted according to the opening degree of the immersion nozzle inlet by adjusting the stopper position up and down. In the filling of the mold, the exit of the mold is closed with a dummy bar, and then the stopper is opened to pour molten steel in the tundish into the mold. After a certain time, the molten steel level in the mold reaches a position that can be detected by the molten steel level sensor attached to the upper part of the mold. When the molten steel is sensed by the water level sensor and the molten steel is filled to the level to start casting, the continuous casting operation is automatically started at the same time as the dummy bar on the mold exit side is pulled out. After that, by automatically controlling the position of the stopper so that the height of the water surface is constant by the surface detection sensor to perform the automatic continuous casting operation.

According to the present invention as described above, by sensing the amount of change in the weight of the molten steel in the ladle and tundish over time to detect the amount of molten steel flowing into the mold to control the moving position of the stopper to meet the various casting conditions By controlling the amount automatically, it is possible to make the molten steel in the mold rise up to the time of automatic casting start, and to prevent the immersion nozzle from clogging, thereby smoothing the flow of molten steel.

Claims (1)

The process of detecting the weight of molten steel in the ladle and the weight change of the molten steel in the tundish over time, the process of calculating the amount of molten steel flowing into the mold through the immersion nozzle using the detected weight change of the molten steel, and a predetermined time And a step of dynamically controlling the position of the stopper so that the hot water surface in the mold can be filled up to the casting start position.