EP0881018B1 - Watercooled mould for continuous casting - Google Patents

Abstract

Process for measuring and regulating temperature and amount of the cooling water of a continuous casting mould comprises measuring the cooling water temperature of a mould wall on at least two sites in the region of the discharge openings of a copper plate and the water tank, adjusting a temperature profile from the values measured over the width of the copper plate and comparing temperature profiles with each other obtained at time intervals.

Description

The invention relates to a liquid-cooled continuous casting mold with each other independent mold walls made of copper plates.

When continuously casting steel in liquid-cooled plate molds, in particular for the production of thin slabs from steel with strand thicknesses between 150 and 40 mm at comparatively high casting speeds using at least one dip tube is located in the mold in the area of the mold mouth due to the comparatively low thermal conductivity of the steel initially only a thin, solidified melt and as a result of their still very high temperature relatively flexible strand shell formed. Because this inside the mold and after leaving the mold the ferrostatic pressure which still has to withstand liquid melt inside, it is necessary that the resulting strand shell is as uniform as possible over the circumference Has thickness. Your education depends on a number of interacting factors such as casting speed, steel temperature, material, strand geometry, Immersion mold, taper of the mold and the type and composition of a slag-forming lubricant that, when applied to the mold level, reduce the inevitable friction between the strand shell and the mold should. It is particularly important that the lubricant is evenly distributed in the area of the mold walls, this in the form of a so-called Casting powder applied to the mold level, thereby melting and by oscillating movements of the molten steel between these and the mold walls arrives. The lubricant should spread as evenly as possible between the strand shell that forms and the mold walls is related with the heat transfer conditions between the strand shell and the mold wall of particular importance. Through careful temperature measurements In the area of the mold walls, conclusions can be drawn about the Distribution of the heat flows, especially across the mold width. This is important because for the safe casting of slabs and especially thin slabs knowledge of specific heat transfers of the type mentioned at the outset Chill broad sides and especially in the middle of the slab in the area of the dip tube is of particular importance. This way, malfunctions can be avoided in good time or counteracted them, for example by the diving spout caused flow anomalies, uneven thickness of the lubricating film from Pouring slag, high membrane effect of the strand shell especially in the Slab center, turbulence of the mold level caused by the slab width become. There are also consequences of non-uniform heat transfer caused, for example, by turbulence of the steel in the mold by a temperature measurement recognize in time. This is particularly important because due to the anomalies mentioned in the casting process, in particular a possible one Deviation of the strand shell formation from the mold center longitudinal cracks in the Strand surface up to breakthroughs, so-called adhesives can. Corresponding disturbances occur at the strand shell at the same time thermal partial loads on the copper plates, leading to the reduction the service life of the mold.

In the prior art, a plate mold for is from DE 24 15 224 C3 Slabs known, the mold walls have cooling chambers, each delimited Include cooling areas. To the inlet and outlet pipes for cooling water the broad side walls are measuring elements for determining the amount of heat dissipated or the cooling capacities arranged. With the help of these measuring elements a Average value of the cooling capacity of the cooling chambers, which one Average generator is fed in, with which the conicity of the narrow sides is controlled becomes.

From DE 41 17 073 C2 it is known with the help of calorimetric measurements the integral on a rectangular or convex thin slab mold and determine specific heat transfer on each individual copper plate. An online comparison of the specific heat flows from the one facing the steel Copper plate side to the water-cooled side especially the narrow sides, with those of the two broad sides, allows regulation of the narrow side conicity regardless of the individually selected casting parameters.

The disadvantage here is that differentiated information in the molds mentioned about the partial heat flows along the mold width are not made. This is also disadvantageous because for the safe casting of slabs and especially of thin slabs at comparatively high casting speeds a determination of differentiated specific heat transfers in the area of the broadsides and especially not in the middle of the slab in the area of the dip tube becomes. Only with knowledge of these specific heat transfers can a regulation of the heat flows over the entire broadside of the mold and so that over the entire slab side can be reached in order to disturbances in particular to avoid by uneven formation of the strand shell.

To create favorable conditions for casting thin slabs, a plate mold with water-cooled, known narrow side walls clampable between broad side walls, with Means for adjusting the shaping cavity to different Strand dimensions and the casting cone, with an oscillation device. at In this mold, the broad side walls have at least three side by side and mutually independent cooling segments, these being symmetrical are divided to the center axis and separate in the area of the mold outlet Have connections for the independent supply of a liquid cooling medium. There are temperature sensors in the wall of the chambers facing the strand provided with which the temperature difference between individual chambers or zones can be detected. The cooling water temperature of a mold wall is at a point in the area of the drain openings of a copper plate and the associated water tank measured. The temperature readings of the The mold wall and the cooling water are a controller for changing the Taper of the mold narrow sides or to change the mold oscillation switched.

However, this division into separate chambers or zones also has the disadvantage that that on both sides of dividers of adjacent chambers or zones considerably can form different temperature flows that only with comparative longer time delay can be adjusted. A sensitive detection of partial heat flows or heat flow differences For example, over the entire width of a mold side wall is in the known design of the cooling segments is not satisfactorily possible.

From DE 34 23 475 A1 is a continuous casting mold with wide side walls and adjustable Narrow side walls made of copper plates are known in the case of thermocouples arranged exclusively in the narrow side walls above their height should be and the temperature measurement values for controlling the casting parameters such as Oscillation, lifting height, frequency and mold powder properties were used.

Starting from the aforementioned prior art, the object of the invention based on specifying an improved continuous casting mold, which is suitable in Inside the mold, heat flows are formed in the melt by means of sensitive, differentiated measurements of the heat flows corresponding to these of the cooling water flowing through the mold walls without any time delay to capture in time control impulses to regulate unwanted Heat exchange conditions, especially with regard to training derive the strand shell in the area of the mold walls.

The task is solved with a continuous casting mold with independent of each other Mold walls made of copper plates, the lower part of the Broad side wall of the mold the inlet of cooling water and in the upper area of the Broad side wall of the drainage of cooling water is arranged, in close succession and each in a vertical plane cooling channels with inlet bores and outlet bores are arranged, the inlet holes cooperating the Form water inlet of the cooling water flow into the cooling channels of the mold wall, while the sum of the drain holes combined the water drain form, and in the cooling water inlet at least one temperature sensor and one Dispenser is arranged for the inflow amount per unit of time and also in Water drainage area between a copper plate and the cooling water drainage openings of the water tank, in particular at least per broad side plate Two places temperature sensors are arranged, the signal lines together with the signal lines of the temperature sensors of the water inlet to a computer, preferably with an online screen.

The mold according to the invention enables a differentiated statement about the Distribution of partial heat flows along the mold width and thus a simple one and safe temperature control of the heat flows close to the wall of the melt inside the mold including the middle of the broadside in the area of the dip tube or the diving spout. At the same time, it is possible along the width of a Chill mold and especially in the area of the diving spout compared to the other areas of the broad sides and to the narrow sides an extreme sensitive and uniform cooling performance and thus disturbances Avoid, for example, the flow shadow caused by the diving spout non-uniform lubricating film thickness, high membrane effect of the strand shell in the Slab center and due to turbulence of the casting level across the slab width can be caused.

What is essential here is the measure that the partial or integral heat flows of the cooling water or the melt across the mold width in the form made visible by temperature profiles. This measure allows the Pour an instant overview of the various heat flows and especially their change in time and enables immediate intervention obviously noticeable faults. Limit values can also be drawn up that can be used to prevent breakthroughs. Especially It is advantageous that the temperature profiles of cooling water or melt be made visible on an online screen.

Further configurations of the mold are in accordance with the subclaims intended.

According to a preferred embodiment, the water drain openings are between Copper plate and water box are evenly distributed in the mold width and each designed for the passage of a constant, equal amount of water.

The continuous casting mold according to the invention is both for the production of thin slabs made of steel with strand thicknesses between preferably 40 and 150 mm comparatively high casting speeds as well as for billet molds for Continuous casting of rectangular or round-shaped continuous casting profiles provided.

Figur 1

im Querschnitt einen Teil einer Kokillen-Längswand mit zugeordnetem Wasserkasten und Anordnung einer Thermokupplung mit Wärmefühlern;

Figur 2

eine Ansicht einer Kokillen-Breitseitenwand mit Anordnung von Kühlwasser-Temperatur-Meßeinrichtungen im Bereich des Wasserzulaufs sowie im Bereich des Wasserablaufs, teilweise im Schnitt;

Figur 3

mehrere Temperaturprofile entlang einer Breitseite einer Kokille im Vergleich mit in Zeitintervallen gewonnen Temperaturprofilen.

Details, features and advantages of the invention result from the following explanation of an exemplary embodiment schematically illustrated in the drawings. Show it:

Figure 1

in cross section part of a mold longitudinal wall with an associated water tank and arrangement of a thermal coupling with heat sensors;

Figure 2

a view of a mold broad side wall with arrangement of cooling water temperature measuring devices in the area of the water inlet and in the area of the water outlet, partly in section;

Figure 3

several temperature profiles along a broad side of a mold in comparison with temperature profiles obtained in time intervals.

Fig. 1 shows an existing copper mold side wall 1 with a Metal melt bath 2 'facing surface part 3. In the solid wall made of copper are arranged in close succession of coolant holes 4, the bottom of are forced to flow above with cooling water. These open on the upper side in a collecting channel 10, which by means of drain holes 5 in a water tank 7 transfers. This is with the plate-shaped elements 6 and 11 of the water tank 7 trained.

In the area of the drain hole 5 there is a thermal coupling 8 in the form of a copper longitudinal bar with channels to accommodate the individual Thermal sensors 20 (Fig. 2) leading signal lines 9. The thermal coupling can For example, be an independent assembly that the individual thermal sensors 20th records with their signal lines 9. It can be used with TP 100 silicone in Corner area of the wall part 6 can be fastened in such a way that it has at least two Surfaces in the flow area of the coolant. Also per measuring point a hole is drilled through the water box in the upper area, which can then be provided with a sensor from the outside.

Fig. 2 shows the surface part 3 of a plate mold with an inventive Plenty of cooling water drain holes 5 in the upper area of the broad side wall 1 in a horizontal projection on both sides of the dip tube 21. In the lower Area of the broad side wall 1 are in for the supply of cooling water close sequence and each in a vertical plane with the drain holes 5 Inlet bores 15, also on both sides of the mold wall center plane v-v. The bores 15 cooperatively form the water inlet 24 of the cooling water flow into the cooling channels 4 of the mold wall 1, while the sum of the drain holes 5 taken together form the water drain 25. On the right and to the left of the median plane v-v are the side closure of the Broad side wall 1 forming narrow side walls 22 and 23. Between each two water drain holes 5, the thermal sensor 20 is installed. In doing so in each case two water drain holes 5 arranged next to one another with two in the same vertical plane arranged water inlet holes 15 each Flow field A, B, C, D or A ', B', C ', D'.

3 shows a three-dimensional diagram with the representation of temperature profiles, measured across the width A 'to D of a slab mold plate with, for example, four that are separated in time and can be compared Corresponding temperature profiles at intervals of ten time units the time axis Z. The width of the mold plate is on the abscissa x-x and the value of the measured heat transport is plotted on the ordinate Y. The The representation corresponds, for example, to a diagram on the computer screen and enables immediate evaluation or correction in the event of a deviation from a given temperature profile.

LIST OF REFERENCE NUMBERS

1

Wide side wall

2

Steel melt bath

3

Wall side / surface part

4

Cooling water bore

5

Cooling water drain hole

6

Plate member

7

cistern

8th

thermocouple

9

signal line

10

collecting duct

11

Plate member

15

supply boreholes

20

thermocouple

21

dip tube

22

Narrow side walls

23

Narrow side walls

24

water supply

25

water drain

Claims (5)

1. Liquid-cooled, continuous casting chill mould with mutually independent chill mould walls of copper plate, wherein the inlet (24) of cooling water is arranged in the lower region of the wide side wall of the chill mould and the outlet (25) of cooling water is arranged in the upper region of the wide side wall, wherein cooling channels (4) with inlet bores (15) and outlet bores (5) are arranged in close succession and each in a respective vertical plane, wherein the inlet bores co-operatively form the water inlet (24) of the cooling water flow in the cooling channels (4) of the chill mould wall, whilst the total of the outlet bores (5) together form the water outlet (25), and at least one temperature sensor and a transmitter for the feed quantity per unit time is arranged in the cooling water inlet (24), and wherein temperature sensors (20) are arranged in addition in the water outlet region between a copper plate (1) and the cooling water outlet openings (5) of the water tank (7) per wide side plate at at least two locations, the signal lines of which sensors together with the signal lines of the temperature sensor of the water inlet are connected to a computer with an on-line display screen.
2. Chill mould according to claim 1, characterised in that a thermo-coupling element containing temperature sensors is arranged in the region of at least each second outlet opening (5) and preferably fastened by silicon of type TP100 or that for each thermosensor a respective bore, which can be provided from the outside with a thermosensor, is formed in the water tank in the region of the outlet bore (5).
3. Chill mould according to claim 1 or 2, characterised in that the temperature sensors (9) are arranged symmetrically relative to the centre axis of each chill mould wide side (1) as well as in casting direction.
4. Chill mould according to one of the preceding claims 1 to 3, characterised in that the cooling water outlet openings (5) are uniformly distributed over the width of the wide side walls (1) and a respective temperature sensor is installed between each two outlet openings (5).
5. Chill mould according to one of the preceding claims 1 to 4, characterised in that the water outlet openings (5) are arranged to be uniformly distributed between copper plate (1) and water tank (7) in the chill mould width and are each formed for the passage of a constant, equal water quantity.

Images