MXPA98007907A - Procedure for the optimization of the surface quality of colada conti - Google Patents

Abstract

The present invention relates to a process for the production of ingots in a foundry installation, in particular steel bars, in which the molten metal is introduced into a continuous casting mold and emerges from the mold in a partially solidified condition , the movement of the rope is detected in an immediate area as possible after emerging from the mold, the sequence of movement is detected without contact and without delay by sensors that respond to radiation, and the sensors are designed and arranged such that they produce a signal of measurement that can be evaluated with respect to the behavior displacement-time of the rope, the process is characterized by the following steps of the process: a. covering the surface of the molten metal with a foundry powder that forms a molten slag to produce a lubricating film between the surface of the rope and the inner wall of the shell; detect and transmit a measured value that characterizes the friction between the surface of the chord and the chill wall to an evaluation unit in the form of a computer; also transmit to the computer the measurement signal that characterizes the displacement-time behavior of the string; correlating in the computer the measurement values or signals related to the displacement-time behavior of the rope and to the friction of the chord in the shell, with comparable and associated magnitudes and compared with a nominal value, such that, e. the nominal value is formed as an average rope speed value from the displacement-time behavior of the rope, f. generate from the deviation between the real and nominal values a signal to change the composition of the melting powder in the sense of reducing the coefficient of friction and / or the oscillation of the shell, g. whereby the displacement-time behavior of the chord is detected optically by means of a diode line camera positioned adjacent to the chord on its narrow side, whose orientation corresponds to the direction of casting.

Description

PROCEDURE FOR THE OPTIMIZATION OF CONTINUOUS COLD SURFACE QUALITY DESCRIPTION OF THE INVENTION The present invention relates to a method for optimizing the surface quality of the continuous casting of steel casting produced in a melting apparatus. When casting continuous casting or rope in continuous casting apparatus the rope or casting formed is generally expelled with a constant exit velocity. The level of the casting in the ingot mold is kept constant by regulating the course of the melt from the distributor. A casting apparatus, especially ingots or lupins, pour with a constant course of the melt from the distributor and regulate the level in the mold by the variation of the extraction speed of the cord or casting.

These two measurements are known to the technician, so they do not need a special indication of references. In both cases, in the first, more simply than in the second, they are made to determine the anomalies of the field of the shell in attempts to measure the friction relations between the casting and the shell. These measurements are structured in such a way that the force of movement for the movement of the shell is measured during the casting and compared with the forces in an empty course for this have been used and investigated to the present oscillating impellers of the driven shells hydraulically or mechanically For a system of this type of mechanical drive is known as "Concast Standard News" volume 30 1/1991 p. 4-5. A suitable hydraulic shell drive system is known from DE 35 43 790 C2. In view of the shaping and the quality of the casting surface, it is known (for example by "Stahl und Eisen" 108 (1988 no. 3, pages 1125 to 1127) that in powder casting coves the paint powder acquires great significance. castings that are placed using it for the formation of a film of lubrication between the wall of the shell and the layer or shell of the casting.Therefore it has also been tried (Stahl and Eisen 107 (1987) no 14, 15 pages 673 to 677) to obtain a conclusion on the compartment of the casting in the shell by measuring the traction force in the moving process, for this a corresponding force measuring device has been installed in the cold casting.This procedure is naturally only suitable for a During the actual operation phase, it is not possible to apply this method, since for the formation of the casting surface together with the technique of lubrication between the shell and the shell of the casting there are also variations within the mold, for example promoted by the oscillation parameter (thrust height, thrust frequency, shape of the curve as well as the steel material itself, also The pull speed of the rope, the cooling conditions, as well as the temperature of the steel and also the type of casting, especially in the rolling of castings, can not be reached by a comparison of the oscillation course of the steel. the shell in vacuum operation with respect to the operation of casting, which are suitable to be applied directly to the casting operation. In all these considerations, the speed of the rope or casting in the mold has been assumed to be of uniform velocity, apparently due to the fact that also the extraction of the laundry is carried out continuously by means of rollers that rotate uniformly. However, the actual speed of the casting is greatly influenced by the friction relations in the mold. This is recognizable to the naked eye when seeing the movement of taking and leaving the laundry (see Stahl and Eisen) (1987) NO 14, 15, page 673 to 677. For the -DE 38 06 583 Al is known, the capture the course of the movement of the casting in an area as close as possible to the position of abandonment of the shell, where the measurement signals through a diode oscillator chamber is conducted to an evaluating unit or indicator unit. The known method of this step serves to determine oscillations characteristic of the casting or of the apparatus, and in this way adjust the movement or the traction form of the whole installation, avoiding critical areas. The invention pursues the objective of finding an improvement in the known measurement methods, which allows an immediate influence on the parameter of controlled operation to improve the quality of the surface. The present invention achieves this purpose by the characteristic of the process step given in the main claim. Other developments of the solution according to the invention are indicated in the subclaims. According to the invention, the actual path of the rope is measured and with this the time course of the speed with high accuracy. The relative velocity thus obtained is compared with other influencing magnitudes equally captured, and they are related to an adequate correlation procedure, essentially, with a calculation of the casting influence. The measurement procedure offers the time course of the casting path as original information. For the formation of the difference with an average path of form, the temporal course of the relative path or the relative velocity with respect to the nominal path or the nominal velocity. By the deviation of the nominal value and the actual value a control signal is formed to vary the composition of the laundry powder in the sense of a decrease in the friction value and / or the oscillation of the mold. Through the connection with the impeller cylinder force, the work or friction power in the impeller system is determined in reference to the thrust of the shell, and the magnitudes of influence are brought to an optimum state in correspondence with the quantities pursued. They have obtained. By means of an on-line measurement on a line using the correlation relationships found, a closed regulation circuit is structured and has an influence on the surface contouring magnitudes pursued, for example at the pour mark depths and at the distances of the laundry brands. In an advantageous embodiment, the signal for varying the oscillation of the shell of a control unit of the oscillation impeller is switched, in such a way that the movement impulse transmitted from the shell to the casting or rope is as slight as possible or is close of the null value. As a measurement value, it is proposed in the hydraulic drive to use the measured value of the differential pressure in the hydraulic cylinder between the vacuum course and the operating state. A mechanical device can obtain that value by a force measuring device. The influence of the friction value is taken in large proportion from the lubrication of the rope. According to the invention, in the variation of the current value with the nominal value, the casting powder will be varied in such a way that the friction value decreases. For this purpose, it is proposed to vary the mixing ratio of different casting powders among themselves. and, if necessary, have an influence on the state of aggregation of the casting powder so that by a pre-melting at least it softens and even better becomes fluid, before it is introduced to the melt that is in the mold. An example of the invention will be described with reference to the accompanying drawings, where: Figure 1 shows the primary conformation, Figure 2 is a typical expression, and - Figure 3 is the variations of the wash path curves or rope. Figure 1 shows a rope 11, which is conducted in a shell 12, leaving the rollers 14. The shell 12 is joined with a supply of laundry powder, which is connected by means of interceptors 16 to the container of laundry powder 15. The supply of laundry powder 17 is further conducted through a heating device 18. On the narrow side of the rope 11 a sensor has been provided., here a diode scan camera, which captures the diode scan of the rope, where the camera coincides in its direction with the direction of casting. The diode scanning chamber 21 is connected via a measurement line 28 to the measurement 22 for the movement of the rope in reference to the section 24 and the speed 23. The signals with respect to the variation of the speed of The rope and the rope path are led to a calculator 26 and possibly to an indicating device 25, and possibly to a printer. Other parameters 27 are also communicated to the calculator 26. On the output side, the calculator 26 is connected by a control conduit 31 to a control component 32 with adjustable interceptors with actuators 16, for the container of the laundry powder 15 as well as by means of a control building part 33 with the heating apparatus 18 for the laundry powder. Through a control conduit 34 the calculator 26 is also linked to a control component 35 for the control of the element 13. Figure 2 shows a typical expression of the captured measurement signals. In the upper part there is a cut of the average velocity of the shell which in the given example oscillates correspondingly in a sinusoidal curve. The average speed of the joint casting is shown below and the current casting speed shown in the region directly below the mold is superimposed on it. It is clearly recognized that depending on the friction and in the case of short-term adhesion of the casting shell to the internal wall of the mold, the movement of the cord or casting in the vicinity of the mold, the sinusoidal curve Subposed shows the real road of the shell, below shows the current path of the rope in the vicinity of the shell.

Both in the taking of the speed of the shell and the way of them is the measured value and not the calculated value. The represented curve is an example and shows characteristic real shapes with evaluable points. From the arrangement of the minimums, the maximums and the investment points, the technician has the possibility of drawing conclusions regarding the actual behavior of the rope shell or casting in the shell, to judge uses the position of the rope with respect to the time points T with the curve shapes in the points A. The section S is here the direct derivation of the velocity V. Figure 3 shows variations of the path of the rope. It should be noted that the radii of curvature of the individual curves or points A, as well as if necessary the change of direction. Due to the influence on the oscillation of the mold and the casting powder, an influence is made on the conformation of the real path of the rope or casting.

Claims (7)

1. A method for producing ingot ropes in a casting apparatus, especially continuous steel castings, in which the fluid metal is introduced into a passage mold and in a partially solidified state. it is removed from the shell, the course of the movement of the rope is captured in an area that is most likely close to the abandonment by the rope of the shell, the capture of the course of the movement is made without touch and free of disturbances by the radiation of sensors corresponding, and the sensors are so placed and arranged, that they generate a measurable measurement signal with respect to the behavior of the path-time of the rope or casting, the process, characterized by the following process steps: a) the surface of The level of the laundry is covered with a laundry powder that forms a liquid slag for the generation of a lubricating film between the shell of the rope and the internal wall of the shell; ) a measurement value characterizing the friction between the shell of the rope and the wall of the shell is captured in an oscillating installation and is conducted to an evaluation unit constructed as a calculator; c) the measurement signal that characterizes the path-time behavior of the string is also entered into the computer; d) in the computer the measurement values or signals of the path-time behavior of the rope and the friction of the chord in the shell are transformed and linked to affordable quantities and compared with a nominal value; e) the nominal value is formed as the average value of the speed of the rope or cast, from the path-time behavior of the rope; f) by the deviation of the nominal value and the actual or actual value a signal is produced to change the composition of the lubrication powder in the sense of a decrease in the friction value and / or the oscillation of the mold.

2. The method according to claim 1, characterized in that the signal for changing the oscillation of the shell is thus switched to a control unit of the oscillating impeller that the moment of movement transmitted from the shell the rope becomes low or close to a null value.

3. The method according to claim 1, characterized in that the measurement value which characterizes the friction of the chord in the shell in the oscillation device of the hydraulic impulse shell is formed from the pressure difference in the hydraulic cylinder between the Vacuum running state and in operating state.

4. The method according to claim 1, characterized in that the measurement value that characterizes the friction of the chord in the shell in a mechanical impeller is taken from a force measuring cell disposed in the oscillation bar.

5. The process according to claim 1, characterized in that the mixing ratio of different laundry powders is varied among themselves.

The process according to claim 5 or 1, characterized in that the aggregate state of the casting powder is varied before its contact with the fluid metal in the mold, for example it is softened or fluidized by the addition of heat.

7. The method according to claim 1, characterized in that, the path-time behavior of the bar is optically captured by means of a diode scanning chamber disposed laterally next to the rope on its narrowest side, which coincides in address with the pouring direction. SUMMARY OF THE INVENTION The invention relates to a method in a casting apparatus for the production of continuous casting, or rope, especially continuous steel castings, in which the course of the movement of the casting is captured and influenced thereon. The invention is characterized by the following process steps: a) the level surface of the laundry is covered with a laundry powder that forms a liquid slag for the generation of a lubricating film between the shell of the cord and the inner wall of the laundry. the shell; b) a measurement value characterizing the friction between the shell of the rope and the wall of the shell is captured in an oscillating installation and is conducted to an evaluation unit constructed as a calculator; c) the measurement signal that characterizes the behavior c amino-t i me of the string is also entered into the computer; d) in the computer the measurement values or signals of the path behavior of the rope and the friction of the chord in the shell are transformed and linked to comparable magnitudes and compared with a nominal value; e) the nominal value is formed as the average value of the speed of the rope or cast, from the path-time behavior of the rope; f) by the deviation of the nominal value and the actual or actual value a signal is produced to change the composition of the lubrication powder in the sense of a decrease in the friction value and / or the oscillation of the mold.