US 4,774,999 AGranted

Process for automatic control of the startup of a continuous casting apparatus

AssigneeArbed S.A.

InventorAndre Kraus

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Abstract

At the latest before response of the measuring mechanism which senses the filling state of the melt tundish the opening rate of the outlet of the tundish is brought to near its standard opening rate and, after obtaining a clear signal from the filling state measuring mechanism or reaching a first predetermined filling height, the withdrawal mechanism is switched on and the withdrawal speed delayed for determination of the opening rate of the outlet. Advantageously the speed of the discharge rollers is measured by a tachometer which transmits a normalized signal which is then multiplied by a signal determined by the standard opening rate. The resultant signal controls the opening rate of the outlet. After the running stage of the withdrawal mechanism or after attaining a second predetermined filling height which is higher than the first filling height, only an I-governing branch of the control circuit controls the opening rate of the outlet and, after reaching a third predetermined filling height, which corresponds approximately with the standard desired filling height, control is transferred to an I-P regulation.

Claims12

Dependent claims

A process for automatic control of a startup of a continous casting apparatus having a tundish for receiving molten metal, a stopper vertically movable in the tundish for defining a range of openings of an outlet of said tundish in accordance with respective positions of the stopper, a mold receiving and cooling said moten metal, said mold having a level sensor, an immersion tube connecting said tundish with said mold and a withdrawal mechanism having a plurality of withdrawal rollers downstream of said mold, comprising the sequential steps of:

(a) shifting the stopper to a predetermined maximum upper position forming an opening larger than a standard opening corresponding to a standard continuous-casting position of the stopper for introducing into a mold of said apparatus through the immersion tube a large amount of molten metal for preheating said mold;
(b) solidifying a part of said molten metal in said mold;
(c) retaining said stopper at said predetermined maximum position for a short period of time sufficient to fill said mold with said molten metal to a level of filling at which a first stable signal, free from splashing signals resulting from splashes of incoming molten metal, is produced by the sensor;
(d) starting the movement of the rollers of the withdrawal mechanism upon the lapse of said short period of time after said stable signal is produced and controlling the speed of said rollers corresponding to the casting speed of said incoming metal by measurement of the roller speed;
(e) moving said stopper down towards said outlet to a second position below said standard position;
(f) retaining said stopper at said second position for another period of time for distributing the incoming metal in said mold;
(g) moving said stopper up to said standard position to form said standard opening;
and
(h) thereafter controlling the position of the stopper by continuously comparing a measured level of the molten metal determined by said sensor with a preset value of said level.

6 more elements

An apparatus for continuous casting of metal, comprising:

a tundish receiving incoming molten metal and having an outlet in a bottom thereof for passing of molten metal;
a stopper shiftable up and down in said tundish opening and closing said outlet, said stopper having a predetermined maximum position defining a large opening of said outlet;
an immersion tube connected to said outlet for conducting said molten metal;
a continuous casting mold below said tundish and connected therewith by said tube, said mode receiving said molten metal;
a withdrawing mechanism below said mold having a starting head closing said mold and forming a bottom of said mold for distributing the metal being cooled in said mold, said mechanism including a plurality of withdrawing rollers along flanks of a continuous casting emerging from said mold;
and
means controlling the opening of said outlet of said tundish, said means comprising:
a detector for a level of said incoming metal, said detector having a source of radiation at an upper part of said mold, and a sensor receiving a signal originating from said source,
a speed sensor detecting an actual speed of said rollers,
an amplifier receiving a signal from said sensor of said detector, and
a controller receiving a signal of an actual level of said incoming metal from said amplifier and said signal of said actual speed, said controller having
a circuit for moving said stopper from a null position up to said maximum position, and
a threshold circuit controlling a sequence of said stopper shifting
to switch on said speed sensor only after said maximum position of said stopper reached and said maximum position is retained for a short period of time, allowing said mold to be filled with said incoming metal to a first level of filling of said mold corresponding to a first stable from said detector free from splashing signals with subsequent moving of said stopper toward said outlet,
to retain said stopper at a second position below a standard position of the stopper for distribution of metal in said mold,
to shift said stopper to said standard position,
to disconnect a circuit shifting said stopper between said maximum position and the second position,
to connect an integral control circuit, shifting the position of the stopper to said standard position in response according to an increasing level of said filling of said mold by said incoming metal, and
upon reaching a predetermined level of said filling, to connect a proportional control circuit controlling said position of said stopper in accordance with a changing level of said filling compared with a preset value of said predetermined level of the filling.

16 more elements

Dependencies are inferred from the claim text.