JP3130053B2 - How to optimize the surface quality of continuous castings - Google Patents

Abstract

The invention relates to a process in a casting mill for producing continuous castings, in particular continuously cast steel, in which the movement of the casting is determined and modified. The invention is characterised by the following process steps: (a) the melt surface is covered with a casting powder which forms a liquid slag to produce a lubricating film between the casting outer shell and the mould inner wall; (b) a measured value characterising the friction between the casting outer shell and mould inner wall is determined in the oscillation device and forwarded to the evaluation unit (in the form of a computer); (c) the signal which characterises the path-time behaviour of the casting is likewise forwarded to the computer; (d) the computer correlates and links the measured values or signals for the path-time behaviour of the casting and the friction of the casting in the mould to produce comparable values and compares them to a reference value; (e) the reference value is determined as a mean value of the casting speed from the path-time behaviour of the casting; (f) from the discrepancy between actual and reference values, a signal is generated to adjust the casting powder composition in order to reduce friction and/or mould vibration.

Description

Description: TECHNICAL FIELD The present invention relates to a method for optimizing the surface quality of a continuously cast steel material (hereinafter, simply referred to as a continuously cast steel material) cast by a continuous casting device.

When casting a continuous cast steel material with a continuous caster, the continuous cast material (hereinafter, simply referred to as a continuous cast material) is usually carried out at a constant drawing speed. The level of the casting molten metal level in the mold is kept constant by adjusting the flow of molten metal from the distributor, i.e. the tundish. Some casters, such as continuous billet casters or bloom continuous casters, cast at a constant flow of molten metal from a tundish and draw the level of molten metal level in the mold to a continuous casting material. Adjust by adjusting the speed. Both of these adjustment methods are obvious to a person skilled in the art, and the literature relating to this is omitted.

In the case of both methods described above, in the case of the first method,
In order to detect an abnormality in the periphery of the mold, a test for measuring the frictional state between the continuous cast material and the mold was performed slightly more easily than in the case of the second method. In these measurements, due to movement in the mold, the required force is measured during casting and compared to the force generated during no load. In this case, conventionally, a mold vibration driving device driven by a mechanical type or a hydraulic type is used and subjected to a test. For mechanical mold drives, such a system is known as “Cocast St.
andard News "(Vol. 30, 1/1991, pp. 4-5).

A suitable hydraulic mold drive is described in German Patent Publication DE35
Known from 43790C2.

In the case of a continuous casting mold that vibrates in terms of the shape and quality of the continuous casting material surface, a solvent powder (Giesspulver) is used to form a lubricating film between the mold wall and the continuous casting material skin.
Is known to be important (eg, “Stahl und
Eisen "(108 (1988), Issue 3, pages 1125-1127). Thus, information on the properties of the continuous cast material in the mold can be obtained by measuring the drawing force in the drawing operation by the dummy bar. For this purpose, a correspondingly formed force measuring device is integrated into the cold-cast material (“Stahl und Eise”).
n "(107 (1987), Nos. 14 and 15, p. 673-677). This method is, of course, suitable only for the measurement during the pull-out operation with the dummy bar, but during the actual operating phase, this measurement is Application of the method is not possible.

In order to form the continuous casting surface, in addition to some lubrication between the mold and the continuous casting skin, for example, vibration parameters (lifting height, lifting frequency, curve shape) and the quality of the steel itself Depending on the continuous casting material drawing speed, cooling condition and steel temperature, and especially the type of continuous casting material guiding device in casting and rolling, etc., the change in the generated mold is also important, so the mold with no load operation It is not possible to obtain a direct estimate that directly intervenes in the casting operation only by comparing the course of the vibrations with the casting operation.

In all these observations, the speed of the cast material in the mold is assumed to be a uniform speed, the reason for this assumption being probably realized by the rolling rollers, which also rotate the material in the continuous casting. It is because of the facts given. However, the actual continuous casting material speed is greatly affected by the friction state in the mold. This can be seen from the up and down movement of the continuous cast material that is temporarily visible to the naked eye (“Stahl und
Eisen "((1987), Nos. 14 and 15, 673-677)
page)). From the German patent publication DE3806583A1, the course of the movement of the continuous cast material is detected in the area immediately after leaving the mold, the measurement signal is generated by a diode array camera, the evaluation device,
Alternatively, it is known to be supplied to a display device.
From this document, known methods are used to take into account the continuous castings or the natural vibrations of the device and to adjust the operation of the entire device in such a way that critical areas are avoided.

It is an object of the present invention to improve known measuring methods so that controllable operating parameters can be directly controlled in order to improve the surface properties of the continuous casting.

This object is achieved according to the invention by the method steps described in the characterizing part of the main claim. Advantageous embodiments of the solution of the invention are described in the dependent claims.

In the present invention, the actual running distance of the continuous cast material and the time course of the speed are measured with high accuracy. The actual relative velocities obtained therefrom are then compared with other similarly-determined effects, and are sized so that they can be compared with one another by means of a substantially multiple effect calculation with a suitable correlation method. This measurement method provides, as initial information, the time course of the mileage of the continuous casting. The difference according to the average travel path forms the rated travel distance and the rated speed from the time course of the relative travel distance or the relative speed. Using this rated speed as a target value, the friction coefficient and / or
Alternatively, a control signal for adjusting the composition of the solvent powder to reduce mold vibration is formed.

In combination with the cylinder force of the drive, the drive system, i.e. the friction work or friction performance in the mold lifting table, is determined, and the working quantity is optimized in accordance with the given setpoint.

By means of the on-line measurement, the application of the detected correlation forms a closed-loop control circuit for controlling "surface contour" target values such as, for example, casting mark depth and casting mark spacing.

In one advantageous embodiment, the signal from the control of the vibration drive for controlling the mold vibration is such that the impulsive movement transmitted from the mold to the continuous casting is as small as possible or close to zero. As supplied. Hydraulic drives use the measurement obtained from the differential pressure in the hydraulic cylinder between no load and operating conditions as a measure of the friction between the continuous casting and the mold. For mechanical devices, this value is obtained via a load cell. Control of the coefficient of friction
When it becomes high, it is performed by lubrication of the continuous casting material. In the present invention, when a deviation between the actual value and the target value is detected, the solvent powder is adjusted so that the coefficient of friction is reduced. For this purpose, the mixing ratio between different solvent powders is adjusted,
Depending on the case, it is proposed to adjust the state of the solvent powder (assembled state) so that the solvent powder is at least softened by preheating and especially liquefied before the solvent powder is supplied to the molten metal in the mold. ing.

 One embodiment of the present invention is illustrated in the accompanying drawings.

FIG. 1 is a block circuit diagram showing the principle of the present invention, and FIG.
FIG. 3 is a diagram showing a typical example of a traveling distance curve with respect to time of a continuous casting material, and FIG. 3 is a diagram showing a modification of the curve in FIG.

FIG. 1 shows a continuous casting 11, which emerges from a mold 12 and is guided by rollers 14.

The mold 12 is connected to a solvent powder supply device 17, the solvent powder supply device 17 is connected to a solvent powder container 15 via a shutoff device 16, and the solvent powder supply device 17 further includes a heating device 18. Has been guided through.

A sensor is arranged on the narrow side surface of the continuous casting material 11, and in this case, the sensor is formed as a diode row camera 21 for detecting a diode row of the continuous casting material, and the direction of the camera 21 is in the casting direction. Located in.

The diode array camera 21 is a device for measuring the movement of the continuous cast material 11 with respect to the travel distance 24 and the speed 23 via the measurement signal line 28.
Connected to 22. Continuous casting speed 23 and continuous casting distance
A signal relating to the change of 24 is supplied to a computer 26 and, if appropriate, a display device 25, for example a printer.

 Further, a parameter 27 is supplied to the computer 26.

The output side of the computer 26 is connected via a control signal line 31 to an actuator 16 which is normally a shut-off valve of the solvent powder container 15, ie a controller connected to an operating element.
It is connected to a heating device 18 for the solvent powder through a controller 33 as well as to a heating device 18 for the solvent powder.

The computer 26 is connected to the vibration device 13 via a control signal line 34.
Is connected to a controller 35 for controlling.

FIG. 2 shows a typical characteristic curve of the detected measurement signal. At the top, in the example given, a portion of the average speed of the mold oscillating corresponding to a sinusoid is displayed.

Among them, on the one hand, the average continuous casting material speed of the entire continuous casting material is shown, and below that, the continuous casting material speed actual value displayed in the area directly below the mold is shown. . It can clearly be seen that these velocities, in the region near the mold, depend on the friction of the continuous cast skin against the inner wall of the mold and, if appropriate, the short-time adhesion. The sine curve below it shows the actual distance traveled by the mold. Below that is shown the actual travel distance of the continuous casting in the area near the mold.

In the detection of both the continuous casting material speed and the continuous casting material traveling distance, a measured value is obtained, not a calculated value. The curve shown is one example and shows a characteristic actual value shape with evaluable points. From the location of the minimum, maximum, and inflection points, one skilled in the art can estimate the actual properties of the continuous cast skin in the mold. For the purpose of judgment, the person skilled in the art applies the position of the continuous casting at time T having a curved shape at point A. The distance S is a value directly derived from the speed V.

FIG. 3 shows the variation of the continuous casting material traveling distance. Note the radii of curvature of the individual curves at point A and the directional changes that may depend. By adjusting the vibration of the mold and the solvent powder, the actual traveling distance of the continuous cast material can be adjusted.

──────────────────────────────────────────────────続 き Continuing the front page (72) Inventor Parshard, Rotor, Germany, Day 40885 Laatingen, An der Derren 2 aar (72) Inventor Tulum, Hans Gunter Germany, Day 47269 Du Isburg Fertzen, Hans Uwe, Germany, day 47269 Duisburg, Reiserweg 60 (72) Inventor Deppe, Gerd-Joachim, Germany, day 47809 Krefeld , Ibendonk 24 (58) Fields surveyed (Int. Cl. ⁷ , DB name) B22D 11/108 B22D 11/053 B22D 11/16 104

Claims (7)

(57) [Claims] In a casting apparatus, molten metal is introduced into an open mold and is withdrawn from the mold in a partially solidified state, and the course of the movement of the continuous cast material is as much as possible in the region immediately after leaving the mold. Detected, the detection of the course of the movement being carried out by a sensor responsive to light without contact and without delay, said sensor comprising:
When casting the continuous cast material, such as a continuous cast steel material, which is formed and arranged to generate an evaluable measurement signal relating to the traveling distance characteristic of the continuous cast material with respect to time, a) the cast molten metal The liquid surface of the continuous casting material is coated with a solvent powder forming a liquid slag so as to form a lubricating film between the outer skin of the continuous casting material and the inner wall of the mold; b) the continuous casting material outer skin Measuring a value representing the friction between the mold and the inner wall of the mold with a vibration device, and supplying the measurement signal to an evaluation device configured as a computer; c) the time of the continuous casting material A measurement signal representative of a mileage characteristic for the continuous casting is also supplied to the computer; and d) a calculation of the mileage characteristic of the continuous casting for the time and the friction of the continuous casting in the mold. , Each measurement And e) the target value is obtained from the running distance characteristic of the continuous casting material with respect to the time as an average value of the continuous casting material speed. And f) if there is a deviation between the actual value and the target value, a signal is generated and output for adjusting the composition of the solvent powder in order to reduce the coefficient of friction and / or mold vibration. And a step of optimizing the surface quality of the continuous cast material. 2. The vibration adjustment signal of the mold is supplied to a control device of a vibration drive device such that an impact movement transmitted from the mold to the continuous casting material is as small as possible or close to zero. The method of optimizing the surface quality of a continuous cast material according to claim 1, wherein the surface quality is optimized. 3. A measure of said friction of said continuous casting in said mold, wherein said measure is a hydraulic drive of a vibrating device of said mold, wherein said measure is within a hydraulic cylinder between an unloaded state and an operating state. The method for optimizing the surface quality of a continuous cast material according to claim 1, which is obtained from a differential pressure of: 4. The method according to claim 1, wherein the measurement signal indicative of the friction of the continuous casting material in the mold is output from a load cell disposed in a vibrating rod by a mechanical drive. 2. A method for optimizing the surface quality of a continuous cast material according to item 1. 5. The method as claimed in claim 1, wherein the mixing ratio of the different solvent powders is adjusted. 6. The method according to claim 1, wherein the state of the solvent powder is adjusted before contact with the molten metal in the mold, for example, softened or liquefied by supplying thermal energy. Or a method of optimizing the surface quality of the continuous cast material according to 5. 7. The running distance characteristic of the continuous casting material with respect to the time is measured by a diode row camera which is arranged on a narrow side surface of the continuous casting material adjacent to the side of the continuous casting material and whose direction matches the casting direction. The method for optimizing the surface quality of a continuous casting according to claim 1, characterized in that it is detected optically.