EP0636440A1 - Controlling system for a horizontal continous casting plant with a heat-retaining vessel, which is designed as a pressure chamber - Google Patents

Abstract

The proposal is for a controlling system for a horizontal continuous casting plant with a heat-retaining vessel (1) designed as a pressure chamber. Liquid metal can be fed to the heat-retaining vessel via a filling channel (3), the metal being heatable to a predetermined temperature and passed via a feed channel (7) with a discharge opening (8) to a continuous casting mould (10). As an extension of the feed channel (7), a discharge channel (9) is provided above the discharge opening and the molten-metal level (H4) in the discharge channel can be adjusted to a predetermined value by appropriate adjustment of the gas pressure in the heat-retaining vessel. The maximum permissible molten-metal level (H2) in the heat-retaining vessel (1) is specified such that the liquid-metal volumes (V1, V3) flowing from the filling channel (3) and from the discharge channel (9) via the feed channel (7) into the heat-retaining vessel after a pressure reduction has been carried out in the heat-retaining vessel result in a molten-metal level which is lower than or equal to the molten-metal level (H3) at the level of the discharge opening (8). <IMAGE>

Description

The invention relates to a control system for a horizontal continuous casting installation with a warming vessel designed as a pressure chamber according to the preamble of claim 1.

Horizontal continuous casting plants (horizontal continuous casting plants) have prevailed in wide areas. The advantages of producing strips and profiles with such systems are very large. The installation of horizontal continuous casting plants, for example, requires less construction work than for plants for the vertical continuous casting process.

A significant procedural difference between the two processes is that the mold can be flanged directly to a holding vessel during the horizontal process. This makes it possible to heat this vessel and thus let the process run at the optimum temperature of the liquid metal. It is also of great advantage that a casting campaign can run from the beginning to the end with the same temperature of the liquid metal, since with the heating of the holding vessel the temperature losses occurring during the casting campaign can be compensated for.

A significant disadvantage in this composite system, the holding vessel - continuous casting mold - strand, however, is that in the event of a malfunction, the flow of the liquid metal to the mold can only be interrupted under difficult conditions if, for. B. comes to a breakthrough of the liquid metal from the mold or from the solidified metal shell behind the mold.

One possibility for liquid metal interruption is that a slide is arranged between the mold and the refractory wall of the holding vessel, which is closed in the event of a fault. With this slide both the strand and the opening in the wall of the holding vessel are closed. The mold is then flanged and the holding vessel is moved away and emptied. In the case of voluminous continuous casting profiles, the end slide must be split, so that when the mold is flanged off, one slide remains in front of the still liquid profile on the mold and a second slide in front of the vessel opening.

Apart from the difficult actuation of the slide if necessary, such a method requires a relatively large amount of space within the narrow distance between the mold and the vessel wall. Another major disadvantage is that the holding vessel must be emptied after the mold has been separated, because the slide plate does not withstand the pressure and temperature of the liquid metal for a long time.

The invention has for its object a control system for a horizontal continuous casting system with a holding vessel designed as a pressure chamber of the aforementioned Specify the type that ensures a rapid interruption of the flow of liquid metal to the mold in the event of a fault.

This object is achieved in connection with the features of the preamble according to the invention by the features specified in the characterizing part of claim 1.

The advantages that can be achieved with the invention are, in particular, that a rapid interruption of the liquid metal flow through the mold channel takes place through the backflow of the liquid metal located in the casting duct above the continuous casting mold into the holding vessel. The holding vessel does not have to be emptied if there is an accident, but rather it can be heated further so that the continuous casting process can be continued without further delays after the accident has been remedied.

The invention is explained below with reference to the embodiments shown in the drawing.

Figur 1

eine Waagerecht-Strangguß-Anlage,

Figur 2

ein Regelungsprinzip für die Anlage gemäß Figur 1.

Show it:

Figure 1

a horizontal continuous casting system,

Figure 2

a control principle for the system according to Figure 1.

In Figure 1, a horizontal continuous casting system is shown. A holding vessel 1 designed as a pressure chamber with a pressure-tight lid 2 can be seen. A filling channel 3 with a filling funnel 4 serves for the supply of liquid metal from a liquid metal supply 17 (e.g. tilting furnace). An inductor 5 with inductor channel 6 heats the liquid metal FM to the desired temperature in the holding vessel. The liquid metal enters the mold channel 11 of a liquid-cooled continuous casting mold 10 via an inlet channel 7 and a pouring opening 8. Above the pouring opening 8, the inlet channel 7 continues in a pouring channel 9.

The inductor 5 located on the holding vessel 1 is arranged such that the bath flow initiated by it does not interfere with the solidification process in the mold and the inflow of bath into this space, but on the other hand the temperature of the liquid metal both in the vessel and in the siphon-like channels 7, 9 for the mold is kept at the optimum height.

In the cover 2 there is a pressure chamber connection 12 for a pressure channel 13 connected to a pressure generating device 14. Air as well as relatively inactive gases such as nitrogen or argon can be considered as pressure medium. A bath level detection device 15 is provided for measuring the current bath level in the pouring channel 9 and a bath level detection device 16 is provided for measuring the current bath level in the holding vessel 1. The minimum permissible bath level of the liquid metal in the holding vessel 1 is designated as H1 and the maximum permissible bath level in the holding vessel is designated as H2. The bath level at the level of the pouring opening 8 is H3. Since the volume area above the liquid metal bath level in the holding vessel is pressurized, a pouring channel bath level H4 is set in the pouring channel 9 (and also in the filling channel 3) compared to this liquid metal level. The setpoint for this bath level H4 is dimensioned such that the liquid metal flows through the mold channel 11 at an optimum pressure and an optimal speed.

FIG. 2 shows a control principle for the system according to FIG. 1. A control device 18 can be seen, the measurement signals S1 and S2 of the bath level detection devices 15 and 16 and possibly an emergency signal N are present on the input side and the liquid metal supply 17 and the pressure generating device 14 are controlled on the output side via control signals A1 and A2. The measurement signals S1 and S2 correspond to the current spout bath level H4 or the current liquid metal bathroom mirror in the holding vessel.

One task of the control device 18 is to set the gas pressure produced by the pressure generating device 14 in such a way that the desired pouring channel bath level is always set regardless of the current bath level of the liquid metal in the holding vessel. The target value of the pouring channel bath level H4 is determined in such a way that an optimal continuous casting process results, as already mentioned. The gas pressure in the holding vessel is increased or decreased depending on the setpoint / actual value deviation of the pouring channel bath level.

Another task of the control device 18 is to ensure, by suitable control of the liquid metal supply 17, that sufficient liquid metal is always refilled into the holding vessel 1 so that the liquid metal bath level is always between the limit values H1 and H2 (minimum bath level and maximum bath level ) is located.

If an emergency signal N occurs, the control device 18 brings about an immediate reduction in pressure of the pressure generating device 14 and an immediate termination of the addition of liquid metal through the liquid metal supply 17. An emergency signal N occurs when there is a breakthrough of liquid metal from the continuous casting mold 10 or from the solidified one Metal shell comes behind the mold. In the event of such an accident, the further flow of liquid metal into the mold must be prevented as soon as possible, as already mentioned.

.The liquid metal volume V1 in the pouring channel 9 must therefore no longer flow through the pouring opening 8 into the mold channel 11 after the occurrence of an emergency signal N, but must be led back to the holding vessel 1 via the inlet channel 7. The liquid metal volume V1 is determined through the cross section Q1 of the pouring channel 9 and the distance L1 between the bath level H3 at the level of the pouring opening 8 and the pouring channel level H4, ie it applies $\text{V1 = Q1 * L1}$

.

.The liquid metal volume V3 flowing into the holding vessel 1 after the pressure has been reduced is determined by the cross section Q3 of the filling channel 3 and the distance L1, ie it applies $\text{V3 = Q3 * L1}$

.

in das Warmhaltegefäß 1, wodurch der Badspiegel im Gefäß ansteigt. Dieser Badspiegel darf jedoch den Badspiegel H3 keinesfalls überschreiten, um zuverlässig zu verhindern, daß nach erfolgtem Druckabbau Flüssigmetall aus dem Abgußkanal in den Kokillenkanal 11 fließt. Die Volumensumme V2 wird andererseits bestimmt durch den Querschnitt Q2 des Warmhaltegefäßes und eine Strecke L2, d. h. es gilt $\text{V2 = Q2 * L2}$

. Aus der Gleichung $\text{Q1 * L1 + Q3 * L1 ≦ Q2 * L2}$

läßt sich der Mindestwert für L2 ermitteln.After the pressure has been released, liquid metal of the volume total flows $\text{V2 = V1 + V3}$

into the warming vessel 1, whereby the bath level in the vessel rises. However, this bath level must never exceed the bath level H3 in order to reliably prevent liquid metal from flowing out of the pouring channel into the mold channel 11 after the pressure has been reduced. The volume sum V2 is, on the other hand, determined by the cross section Q2 of the holding vessel and a distance L2, ie it applies $\text{V2 = Q2 * L2}$

. From the equation $\text{Q1 * L1 + Q3 * L1 ≦ Q2 * L2}$

the minimum value for L2 can be determined.

ermittelt.The maximum permissible bath level H2 is expediently derived from the equation $\text{H2 = H3 - L2}$

determined.

Since the setpoint of the pouring channel bath level H4 can be changed as a function of the continuous casting process, a change in the then changing distance L1 or L2 also results in a change in the maximum permissible bath level H2.

Claims (2)

Control system for a horizontal continuous casting installation with a holding vessel (1) designed as a pressure chamber, to which liquid metal can be fed via a filling channel (3), which can be heated to a predetermined temperature and via an inlet channel (7) with a pouring opening (8) to a continuous casting mold (10) can be passed on, with a pouring channel (9) provided above the pouring opening in the extension of the inlet channel (7) and the pouring channel bath level (H4) being adjustable to a predetermined value by appropriate adjustment of the gas pressure in the holding vessel, characterized in that the The maximum permissible bath level (H2) in the holding vessel (1) is specified such that the liquid metal volumes (V1, V3) flowing from the filling channel (3) and from the pouring channel (9) via the inlet channel (7) into the holding vessel after the pressure has been reduced in the holding vessel ) result in a bath level that is lower than or equal to the bath level (H3) at the level of the pouring opening (8 ) is. Control system according to claim 1, characterized in that the maximum permissible bath level (H2) can be changed as a function of the setpoint of the pouring channel bath level (H4).

Images