EP1017523A1

EP1017523A1 - Method for optimising the opening rate of steel-casting ladles

Info

Publication number: EP1017523A1
Application number: EP99932822A
Authority: EP
Inventors: Margrit Dislich; Heinz Liebig; Stefan Kirchhoff
Original assignee: Dislich Margrit Dr
Current assignee: Dislich Margrit Dr
Priority date: 1998-07-07
Filing date: 1999-07-06
Publication date: 2000-07-12
Also published as: DE19981284D2; DE19830265A1; AU4907399A; WO2000002688A1

Abstract

The invention relates to a method for optimising the opening rate of the discharge system of steel-casting ladles. According to the method, the position of a discharge opening (16) of a filling pipe (15) in a horizontal plane in relation to an axis of the discharge channel (13) and optionally, the shape of an discharge end (16) of the filling pipe (15) are determined by non-contact detection before the gate filler (27) is metered. These images can be stored in a database with logical values for whether the discharge channel (13) opened reliably in a subsequent casting operation. This enables a map of the opening rate of the discharge channel (13) to be placed over the horizontal position of the discharge end (16). The map can then be used later for filling operations with the gate filler (27). The wear of the lining of the steel-casting ladle (11), the actual height of the entry cross section of the discharge channel (13) and the status of the discharge channel can also be determined and the introduction of the gate filler (27) into the discharge channel (13) can be controlled in dependence on the measured data. The status of the discharge end (16) of the filling pipe (15) for the gate filler (27) can also be determined and its discharge opening (16) can be positioned appropriately horizontal to or above the discharge channel (13), in accordance with the results.

Description

Process for optimizing the opening rate of steel ladles

Description:

The invention relates to a method for preparing the pouring channel of a steel ladle, which can be closed at its lower end by a slide, for a new casting process, the pouring channel above the slide located in the closed position being filled with a free-flowing slide filling compound by means of a fill tube that can be positioned above the pouring channel, and above the pouring channel an accumulation of this slide filling compound is poured on.

The method described above is known. It is common where a container filled with a molten metal can be emptied via a pouring opening in the bottom, which can be closed from the outside of the container by a slide mechanism. If the container were to be infiltrated with molten metal without using the slide filling compound, in practice also called slide filling sand or simply slide sand, this would reach the mechanism of the closed slide via the pouring channel, solidify there and block the slide mechanism. The slide mechanism is therefore protected by a free-flowing mass with which not only the pouring spout is filled but also a certain accumulation is poured over the pouring spout. The pusher filler used has the property of sintering together on contact with the molten metal on the surface of the accumulation and thus forming a dome-shaped shell on which the static pressure of the molten metal rests and which on the other side by the free-flowing slide filling compound is supported. When the slide is opened, this mass flows out of the pouring channel, whereupon the sintered dome collapses under the pressure of the melt and the pouring process is initiated (self-opening).

However, this technique does not always work. Various, partly still unexplored, circumstances are responsible for this. If such measures have to be initiated to open the pouring channel, the quality of at least some of the melt in the container is usually impaired, as a result of which an inferior product or even scrap is produced.

Worldwide, only automatic opening rates (self-opening rates) of around 55 to 75% are actually achieved. The reason for this lies in the fact that in many steelworks the mixture of the slider filling compound is often thrown into the pouring spout manually in bags. As a result, the mass cannot get into the pouring channel in a targeted manner. But even in modern steelworks, where the slider filler is brought into the pouring area through a position-controlled filler pipe, only self-opening rates of around 98% are generally achieved. In Germany alone, the quality of around 500 enamel fillings per year with up to 300 tonnes per filling has to be downgraded. This results in an economic loss of around DM 20 to 25 million a year.

The requirements for a functional slide opening system for steel ladles have increased even more that the final chemical composition of a steel melt is adjusted in the steel ladle according to the methods of secondary metallurgy. The steel ladle is filled with crude steel at around 1700 ° C regardless of the final casting temperature. The final alloy, the treatment of the steel and the heating and cooling of the Steel to achieve the specified casting temperature takes place in the steel ladle. This treatment method increases the length of time the steel stays in the steel ladle from around 15 minutes in the past to around 1.5 to 2 hours today, in extreme cases even up to 8 hours at temperatures of up to 1840 ° C. This long residence time of the steel in the ladle does not have an impact on the dome-forming filling of the pouring channel with slide filling compound. The demands on the steel qualities are so high nowadays that the pouring takes place even in the absence of air in order to avoid reoxidation, carburization and nitriding of the steel. The more disadvantageous are the quality impairments that result from a non-automatic opening of the pouring channel.

The object of the invention is to improve the automatic opening rate of the pouring systems of steel ladles.

The rough operation in the steel mill and the high temperatures constantly prevailing in the steel ladles make this task more difficult because under such conditions it is only possible to record the required parameters to a limited extent.

However, it could be determined that, in addition to a suitable composition of the slide filling compound, which is currently a chrome ore and quartz sand mixture, carbon is added to the carbon in small amounts and in different states, in particular as graphite or carbon black, and the type, formation of the Accumulation and the amount of slide filling compound in the ladle plays a role. The condition of the pouring channel is also important.

Steel ladles are provided with a refractory lining, which can have a thickness of approximately 1 m, especially in the bottom area of the ladle when new. This fireproof lining is significant Subject to wear. It is often only renewed when it has decreased to about 1/3 of its thickness. The so-called perforated brick, which contains the pouring channel, and on the underside of which the slide system for closing and opening the pouring channel is arranged, is positioned in this bottom lining of the ladle. This perforated brick, the top of which is usually slightly below the refractory lining surrounding the ladle, is also subject to considerable wear during the course of the pouring processes, so that the vertical length of the pouring channel decreases with increasing use of the ladle. The pouring channel generally has a funnel-shaped design in the upper area and a cylindrical design in the lower area. When the perforated brick wears, the height of the funnel-shaped section of the pouring channel decreases. This changes not only the distance between the inlet cross section of the pouring channel and a filling tube that can only be positioned at a fixed height above the pouring channel, but also the amount of slide filling compound that is required to fill the pouring channel. The invention takes these circumstances into account.

Another problem is that the optimal position of the fill tube, the exit end of which depends on many conditions with respect to the pouring spout, and can vary from pan to pan. The optimal position of the filling pipe must therefore first be determined.

The stated object is achieved in the most general form according to the invention in that, in a method according to the preamble of claim 1, before metering the slide filling mass by contactless detection, the position of the outlet opening of the filling tube in a horizontal plane with respect to the axis of the pouring channel and, if appropriate, the shape the outlet end of the filling pipe is determined. According to the invention, only the position of the outlet opening of the filling tube in a horizontal plane with respect to the axis of the pouring channel and, if necessary, the shape of the outlet end of the filling tube are thus initially detected. Based on these values, statistics about the self-opening rate depending on the position and possibly the shape can then be created. It is particularly expedient if a raster camera and an image analysis are used as the contact-free measuring system for the detection of the position and, if appropriate, the shape of the outlet end of the filling tube. This image can expediently be stored together with a Boolean value as to whether the pouring channel has opened after the sprue has taken place. A "map" of the self-opening rate as a function of the position of the outlet opening of the filling tube in a horizontal plane with respect to the axis of the pouring spout can thus be created by means of a computer. As soon as sufficient values are available for creating a "map", the system operator can then always drive the filling pipe or its pouring channel in a range of 100% or close to 100% self-opening rate. By means of the data of a self-learning software determined on the basis of the above procedure, however, the positioning of the outlet end of the filling tube is preferably carried out fully automatically. Automatic drive means may be used for this purpose.

The above measures are also important due to the prevailing temperature conditions. These temperature conditions mean that the filling tube for the slide filling compound is subjected to deformation influences, so that after a certain time its outlet opening no longer coincides with the original axis of the filling tube. The outlet end of the filling tube can bend, so that its outlet opening is not only outside the actual axis of the filling tube and thus outside the axis of the pouring channel, by bending the filling tube it can also happen that the direction of the outlet opening changes slightly. Additionally or alternatively, an image of the cone of the filled slide filling compound can also be generated and stored with the raster camera. The state of the cone can be used in conjunction with the position and possibly shape of the filler tube or even to set up a database on the self-opening rate.

An essential requirement for a successful opening of the pouring spout of a steel ladle is that the pouring spout is free before filling with the slide filling compound, i.e. contains no foreign objects such as parts of the refractory lining of the ladle, slag or the like. In practical operation, this is difficult to control by the operator. The invention therefore provides, in a further preferred, independently conceivable embodiment, that the continuity of the pouring channel is checked before it is filled with slide filling compound and the filling process is made dependent on the control result. This check is also carried out with a raster camera and image analysis. The same camera installed above the ladle can be used, which also checks the shape and positioning of the end of the filling tube.

Such a camera can also be used to check the shape of the accumulation of the slide filling compound over the pouring spout and to record further operating parameters, from which further conclusions can be drawn in connection with the opening result for optimal preparation of the pouring spout.

Since a good self-opening rate, as already explained above, also depends on the vertical distance between the outlet opening of the filling pipe and the inlet cross-section of the pouring channel, a further, in principle also independent conceivable concept of the invention, starting from a fixed reference point above the ladle, by means of a non-contact measuring system determines the height of the inlet cross section of the pouring spout and based on this determination, the outlet end of the filling pipe is brought into a predetermined distance above the inlet cross section of the pouring channel. This distance is to be determined according to the particular circumstances of the ladle concerned. In its most general width it can be between 5 and 100 cm, but a common distance is, for example, between 15 and 20 cm. With such a small distance between the outlet end of the filling tube and the top of the perforated brick, ie from the inlet cross-section of the pouring channel, significant wear of the perforated brick, ie a significant lowering of its surface, is important. It is not only a question of the pouring channel being exactly hit for filling with the slide filling compound, but also the subsequent accumulation of slide filling compound over the inlet cross section of the pouring channel is important. When forming the accumulation, it may even be expedient to slowly raise the outlet end of the filling tube. In a preferred embodiment, the invention therefore provides this measure.

Depending on the respective height of the inlet cross-section of the pouring channel, the amount of slide filler mass can also be adapted to the changed volume of the pouring channel and metered in such a way that a certain amount of slide filler mass is nevertheless used for its accumulation above the pouring channel.

The determination of the respective height of the inlet cross section of the pouring channel is expediently carried out using a laser distance measuring device which is attached in a fixed position above the ladle. This type of measurement avoids the difficulties of access to the ladle due to the high temperatures prevailing there. The invention is explained in more detail below with reference to the embodiment shown in the drawings.

Show it:

1 shows a schematic structure of a system for carrying out a method with the features of the invention, FIG. 2 shows the image of a raster camera of the perforated stone environment

Gießpfanne, Figure 3 shows the image of Figure 2 on a screen for one

Plant operator, FIG. 4 the image of the raster camera of the perforated stone environment with a roughly positioned filling tube, FIG. 5 the image of a raster camera with a precisely positioned filling tube,

FIG. 6 shows the image of the raster camera according to FIG. 5 on the screen of the system operator, FIG. 7 shows the image of the raster camera of the perforated stone environment with poured sand, FIG. 8 shows the image according to FIG. 7 on the screen of the system operator,

FIG. 9 shows a schematic illustration of a laser beam

Reflection measurement to determine the distance of the

Outlet end of the filling pipe over an inlet cross section of the pouring channel of the perforated brick.

FIG. 1 shows a ladle 11 carried by a movable ladle wagon 10. A perforated brick 12, which has a pouring opening 13, is embedded in the ladle or in the lining thereof. The pouring opening can be closed by means of a slide 14. The pouring opening 13 is still filled with filling compound 27 in the usual manner. For this purpose, a conventional filling pipe 15 is used, the outlet end 16 of which is positioned above the perforated brick. The filling tube 15 is a Dosage 17, namely fed a differential weight scale, which takes the filling mass 27 out of a storage container 18. To observe the filling of the ladle 11 with slide filling compound 27, a digital camera 19 is provided, which is installed approximately 1.5 to 2 m above the upper edge of the ladle 11. The camera 19 is aligned vertically above the perforated brick 12.

In the same way, a laser distance measuring device 20 is attached. The camera 19 and the laser distance measuring device 20 would then be supplied with power from a power supply unit 21. Furthermore, the laser distance measuring device 20 and the camera 19 are connected to a water or air cooling system 22, depending on the conditions prevailing in the steel mill.

An evaluation device 23 is accommodated in a dry and dust-protected room. This consists of two computers (PCs) with two monitors that are connected via a network and, if possible, with the database of the steel mill. A PC is also equipped with a modem or an ISDN card, a digital I / O card and a frame grabber card. An image processing program is also installed on this PC.

The camera 19 is connected to the frame grabber of the evaluation unit 23 via lines 24 for image transmission. The laser distance measuring device 20 is connected to the digital I-O connection of the evaluation unit 23 via other phases of the same line 24 for the transmission of measurement data.

The signals required for the image and measurement triggering to be described below are obtained from carriers from the plant control of the steel mill. For this purpose, trigger lines 25 are laid between the digital I / O card of the evaluation unit 23 and the system controller 26 of the filling. The filling process is triggered by moving the empty ladle 11 in the ladle carriage 10 to the end position for filling with slide filling compound 27. The end position is determined by limit switches or laser distance measurement using the laser distance measuring device 20. When the end position is determined by the laser distance measurement, the end position is reached when the depth determined by the laser distance measurement increases suddenly; in other words: the end position is reached when the emitted laser beam falls into the pouring opening 13. Reaching the end position is transmitted to the system controller 26 via the trigger line 25. The drive of the ladle car 10 receives an impulse and triggers the stopping of the car 10.

The camera 19 mounted above the ladle 11 records this process and transmits the images (FIGS. 1, 2) online via the lines 24 to the evaluation unit 23. The system operator follows this process online via the expansion unit 23 using the one shown to him there Image (Figure 2). When the ladle 11 reaches the end position for filling and the ladle 10 comes to a standstill, a trigger is triggered and transmitted to the digital I / O card of the evaluation unit 23 via the trigger line 25. An internal signal from the digital I / O card on the frame grabber saves a snapshot of the pan base with perforated brick 12 (image according to FIG. 1) and displays it on the monitor of evaluation unit 23 (image according to FIG. 2).

The system operator can check the condition of the perforated brick 12 on-line on the monitor of the evaluation unit 23. Any contamination by slag, mortar or the like in the pouring channel 13 can be determined and the ladle 10 can be replaced or cleaned.

When the visual inspection by the plant operator has been completed, the software performs an image analysis on the evaluation unit 23. The Software uses the image data to determine the optimal position of the position of the filling tube 14 for the next filling step.

The system operator manually confirms a switch for lowering the filling tube 15 on the system controller 26. The filling tube 15 is automatically lowered into the ladle 11 by a motor drive. If the lowest point is reached (Z direction), a trigger is triggered by a limit switch and transmitted to the digital I / O card of the evaluation unit 23 via trigger lines 25. An internal signal from the digital I / O card on the frame grabber saves a snapshot of the filling tube in the pan at the lowest point (FIG. 3) and displays it on the monitor of the evaluation unit (FIG. 4). Problems that arise can be identified and corrected online.

The data determined by the laser distance measurement by means of laser distance measuring device 20 and the image evaluation are transferred to the controller 26 of the filling process. The filling tube 15 is automatically positioned by the motor drive to the determined end position X, Y, Z direction. The quantities of slide filling compound 27 required for filling depend on the one hand on the steel quality (treatment time, process technology or the like) and on the other hand on the wear of the pan lining or perforated brick 12. This quantity is automatically obtained from the database of the steelworks and that with the laser distance measuring device 20 coupled image evaluation determined.

When the end position of the filling pipe 15 has been reached, a switch for filling the ladle 11 with slide filling compound 27 is actuated manually by the plant operator. This triggers a trigger and transmits it via trigger lines 25 to the digital I / O card of the evaluation unit 23. An internal signal from the digital I / O card on the frame grabber provides a snapshot of the aligned filling tube 15 in the ladle 11 stored (Figure 5) and displayed on the monitor of the evaluation unit 23 (Figure 6). Problems that arise can be recognized online and corrected if necessary.

If the switch for filling the ladle 11 with slide filling compound 27 is actuated by the plant operator, the determined amount of slide filling compound 27 is weighed via the dosage 17, in this case the differential balance, and filled into the pouring channel 13 through the filling pipe 15. During this filling, the filling pipe 15 is automatically moved slowly upwards in order to ensure a uniform distance between the height of the filled slide filling compound 27 and the outlet end 16 of the filling pipe 15. This is controlled via the laser distance measurement by means of the laser distance measuring device 20.

When the required amount of slide filling compound 27 has been filled in, the filling pipe 15 is moved out of the ladle 11 by the operator by actuating a switch on the system controller 26 via a motor drive. This triggers a delayed trigger. The time delay is switched so that the filling tube 15 is no longer visible on the monitor of the evaluation unit 23 and the ladle 10 is not yet moved. An internal signal of the digital I / O card is transferred to the frame grabber by the triggered trigger and a snapshot of the slide filling mass cone of the filled ladle 11 is stored (FIG. 7) and displayed on the monitor of the evaluation unit 23 (FIG. 8). Problems that occur can in turn be recognized online and corrected if necessary.

The laser distance measurement by means of the laser distance measuring device 20 is shown schematically in FIG. 9. An electronic pulse generator controls a semiconductor diode laser periodically. This then emits short infrared light pulses, which are bundled by the transmission optics. over a receiving optical system passes some of these signals reflected by the target to a photodiode, which delivers a corresponding received signal.

An evaluation device now measures the time interval between the transmit and receive pulse. The laser distance measurement therefore works on the principle of the echo sounder. The time interval is counted with a quartz-stabilized clock frequency and the calculated distance value is fed to the device-internal microcomputer, which carries out the further processing of the measured values for the data output.

A serial output supplies the measured distance value as well as status and fault messages via line 24 to the evaluation unit 23.

The most important parameters of the device are set via a serial input and are also transferred to the evaluation unit 23. These are:

Measuring time, measured value resolution, measured value reference level and the like, serial transmission format,

Type of measured value processing program, average height of the pan base, so that it is ensured that the filling tube 15 is always the same distance from the

Pan bottom has, regardless of wear,

Wear of the perforated stone 12 by measuring the crater rim and the depth of a perforated stone crater.

The measured values are stored in a database of the evaluation unit 23.

The image evaluation is described in more detail below: The stored images are evaluated online using self-learning software. The X, Y coordinates of the center point of the perforated brick 12, the outlet end 16, the filler pipe 15 and the slider filler mass stain are then continuously determined with each filling operation and stored in a database. In addition, the diameter of the slider filling cone in the ladle 11 is determined and also stored in the database. A boolean value is assigned to each frame rate for each filling process, whether or not there was self-opening in the subsequent sprue. By assigning and evaluating with neural network technology, it is possible to determine the optimal lance position. A "map" with self-opening rates is created above the feed pipe position. This enables automation of the filling with slide filling compound 27 in order to achieve optimal opening rates. The position of the filling tube 15 above the perforated brick 12 or its pouring opening 13 is continuously adjusted so that it lies in the range of the optimum of the opening rate, that is to say the maximum value of the opening rate above the position.

198 30 265.7 D 592 jhf / bai

DISLICH, DR. MARGRIT July 5, 1999

FUPWPTYALL1942

Reference list

10 ladle cars

11 ladle

12 perforated stone

13 pouring spout

14 sliders

15 filling tube

16 exit end

17 Dosage

18 storage containers

19 camera

20 laser distance measuring device

21 measuring part

22 cooling

23 evaluation device

24 line

25 trigger line

26 Plant control

27 slide filling compound

Claims

claims

1. Method for preparing the pouring channel (13) of a steel ladle (11), which can be closed at a lower end by a slide (14), for a new casting process, in which (method) the pouring channel (13) lies above the slide (14) in the closed position. Filled with a free-flowing slide filling compound (27) through a filler pipe (15) that can be positioned over the pouring channel (13) and an accumulation of this slide filling compound (27) is poured over the pouring channel (13),

characterized,

that before metering the slide filling compound (27) by contact-free detection, the position of the outlet opening (16) of the filling pipe (15) in a horizontal plane with respect to the axis of the pouring channel (13) and, if necessary. the shape of the outlet end (16) of the filling tube (15) is determined.

2. The method according to claim 1, characterized in that the detection of the position and if necessary. the shape of the outlet end (16) of the filling tube (15) is carried out by means of a raster camera (19) and image analysis.

3. The method according to claim 2, characterized in that the image of the position generated by the raster camera (19) and if necessary. Shape of the outlet end (16) together with a Boolean value, whether there was self-opening at the associated sprue, stored.

4. The method according to at least one of claims 1-4, characterized in that an image of the cone of the filled slide filling compound (27) is generated and stored by the raster camera (19).

5. The method according to at least one of claims 1-4, characterized in that, based on the result determined, the outlet opening (16) is tracked into a position from which the emerging slide filling compound (27) arrives as directly as possible into the pouring channel (13).

6. The method according to claim 5, characterized in that the positioning of the filling tube (15) in dependence on the value determined by the measuring system is carried out by automatic drive means.

7. The method according to at least one of claims 1-6, characterized in that the patency of the pouring spout (13) is checked as a preparatory measure and the measures of claims 1-5 are initiated only when the patency of the pouring spout (13) is established.

8. The method according to claim 7, characterized in that the checking of the continuity of the pouring channel (13) by means of a raster camera and image analysis, in particular the same raster camera (19) and image analysis, through which the detection of the position and, if necessary. the shape of the outlet end (16).

9. The method according to at least one of claims 1 to 8, characterized in that starting from a fixed reference point above the ladle (11) by means of a non-contact measuring system, the height of the inlet cross section of the pouring channel (16) is determined and based on this determination the outlet end (16) of the filling pipe (15) is brought into a predetermined distance above the inlet cross section of the pouring channel (13).

10. The method according to claim 9, characterized in that a laser beam reflection measuring system (20) is used as the non-contact measuring system.

11. The method according to at least one of claims 1-10, characterized in that the amount of the filler tube (15) dispensed slide filling compound (27) depending on the determined actual height of the inlet cross section of the pouring channel (13) and thus the actual volume the pouring channel (13) is metered over the slide (14).

12. The method according to at least one of claims 1-11, characterized in that during the pouring out of the accumulation of slide filling compound (27) over the pouring channel (13), the filling tube (15) is moved upwards depending on the formation of the accumulation.