Method and device for early detection of a rupture in a continuous casting plant

Abstract

A device and method for the early detection of a rupture in a continuous casting plant, in which liquid metal is cast into a chill (2) and is withdrawn from the chill (2) in the form of a billet (1), the temperature of the chill (2) being measured, and the temperature of the chill (2) being simultaneously presented with reference to the location at which the temperature was measured and the time over which the temperature was measured.

Description

[0001] The invention relates to a method and a device for the early detection of a rupture in a continuous casting plant, in which liquid metal is cast into a chill and is withdrawn from the chill in the form of a billet, the temperature of the chill being measured. Early detection of a rupture is to be understood here as meaning that it is detected at an early time if there are ruptures of the initially liquid core of the billet through the solidified shell of the billet. However, for the purposes of the invention, early detection of a rupture is also to be understood in principle as meaning the detection of defects in the billet which could lead to ruptures.

[0002] For the early detection of a rupture, it is known to measure the temperature of the chill at various points on the chill and to present the temperature at the measured points on a display. Such a display is shown, for example, in FIG. 4.

[0003] It is the object of the invention to improve the known early detection of a rupture.

[0004] This object is achieved according to the invention by a method as claimed in claim 1 or 2 and a device as claimed in claim 3 or 4. For the early detection of a rupture in a continuous casting plant, in which liquid metal is cast into a chill and is withdrawn from the chill in the form of a billet, the temperature of the chill is measured. The measured temperature of the chill is then simultaneously presented and/or evaluated with reference to the location at which the temperature was measured and the time over which the temperature was measured. In this way, ruptures or defects which may lead to ruptures can be predicted considerably better than by the known method.

[0005] Advantages and details emerge from the following description, the prior art and an exemplary embodiment of the invention. In the drawing:

[0006] FIG. 1 shows a continuous casting plant,

[0007] FIG. 2 shows a chill,

[0008] FIG. 3 shows the arrangement of temperature sensors, represented on the basis of a “developed” chill,

[0009] FIG. 4 shows a known visual representation of measured temperature values, and

[0010] FIG. 5 shows a representation of the temperature with reference to location and time.

[0011] FIG. 1 shows a continuous casting plant. Represented are a casting ladle 4, a distributing launder 3, a chill 2 with temperature sensors 8 for temperature sensing, a billet 1, guide rollers 5, a cutting device 6 and a slab 7. The arrangement of the temperature sensors 8 on the chill 2 is illustrated by FIG. 2. The temperature sensors 8 are connected via a data line 11 to an evaluation device 10 and a display 9 for presenting the temperature with reference to time and location.

[0012] Advantageously coming into consideration as temperature sensors are, for example, thermocouples.

[0013] The early detection of a rupture during the continuous casting of steel serves the purpose of detecting defects in the billet shell at an early time. Defects take the form of stickers and cracks and may lead to a rupture of the billet shell, accompanied by high commercial losses and loss of production.

[0014] FIG. 3 shows a chill 2 in a developed representation. Fitted on the chill 2 in two rows are about n=20 temperature sensors per row. The invention is also used most particularly advantageously with one row of temperature sensors.

[0015] For the visual representation of the temperature i, a bar chart according to FIG. 4 is known. In this, the temperature at the current point in time is indicated for each temperature sensor by means of a bar chart, that is to say the current measured values are indicated.

[0016] The basic idea of the method of visual representation proposed by the invention is the simultaneous representation of location NT, temperature i and time t, as presented in a representation shown by way of example in FIG. 5. For the two rows of temperature sensors from FIG. 3, a visual representation according to FIG. 5 is respectively provided:

[0017] (i) location: the local distribution of the temperature sensors is presented row by row in the same way as before.

[0018] (ii temperature: in each row, the temperature i is indicated by distinguishing colors.

[0019] (ii time: the data successively coming in is presented row by row, so that the time t is represented by going down the rows.

[0020] The temperatures are represented in a particularly advantageous way by different colors. In this case, it is of particular advantage not to allow any continuous differences in color but to assign a specific color respectively to specific temperature regions. For reasons of black-and-white representation, the colors are represented in FIG. 5 by different shadings. Elements of the same color represent regions of the same temperature. 5 is a higher temperature than 4, 4 is a higher temperature than 3, 3 is a higher temperature than 2 and 2 is a higher temperature than 1. The joining lines 12, 13, 14, 15, 16 between adjacent regions of the same color, so-called isochromes, correspond to lines of the same temperature, i.e. so-called isotherms. Vertical lines, i.e. vertical isochromes, are to be interpreted as undisturbed steady-state operation of the continuous casting plant.

[0021] When the defects mentioned above occur, characteristic isochromes form and are easily identifiable for the operator of a continuous casting plant in this form of visual representation. The pattern of the isochromes 12 and 16 indicated in FIG. 5 (top left) shows a region in which a defect has formed with increased temperature, as is characteristic in the case of stickers. The temperature is highest in the interior of the time/location distribution and decreases toward the edges.

[0022] On the same principle, with a converse temperature gradient, there is shown in FIG. 5 (center) a pattern of the isochromes 13, 14, 15 with lower temperature in the interior, as occurs in the case of cracks.

[0023] In a refinement of the invention, the representation according to FIG. 5 is presented on the display 9. However, the invention is also suitable particularly advantageously for the automatic detection of likely defects in the billet which may lead to a rupture. In this case, the representation according to FIG. 5 is not presented on a display but is fed to an automatic pattern detection, which emits an alarm when a significant defect is detected.

[0024] The pattern detection is implemented particularly advantageously on an evaluation device 10. It is particularly advantageous, furthermore, to present a pattern detection on an evaluation device 10 and simultaneously a graphic representation, as shown by way of example in FIG. 5, on a display 9.

Claims

1. A method for the early detection of a rupture in a continuous casting plant, in which liquid metal is cast into a chill (2) and is withdrawn from the chill (2) in the form of a billet (1), the temperature of the chill (2) being measured, and the temperature of the chill (2) being simultaneously presented with reference to the location at which the temperature was measured and the time over which the temperature was measured.

2. A method for the early detection of a rupture in a continuous casting plant, in which liquid metal is cast into a chill (2) and is withdrawn from the chill (2) in the form of a billet (1), the temperature of the chill (2) being measured, and the temperature of the chill (2) being simultaneously evaluated with reference to the location at which the temperature was measured and the time over which the temperature was measured.

3. A device for the early detection of a rupture in a continuous casting plant, in which liquid metal is cast into a chill (2) and is withdrawn from the chill (2) in the form of a billet (1), the device for the early detection of a rupture having a temperature sensor (8) for measuring the temperature of the chill (2) and a display for simultaneously presentating the

temperature of the chill (2) with reference to the location at which the temperature was measured and the time over which the temperature was measured.

4. A device for the early detection of a rupture in a continuous casting plant, in which liquid metal is cast into a chill (2) and is withdrawn from the chill (2) in the form of a billet (1), the device for the early detection of a rupture having a temperature sensor (8) for measuring the temperature of the chill (2) and a pattern detection for evaluating the temperature of the chill (2) with reference to the location at which the temperature was measured and the time over which the temperature was measured.