EP3890906A1

EP3890906A1 - Rolling ingot mould for the continuous casting of aluminium and aluminium alloys

Info

Publication number: EP3890906A1
Application number: EP19809758.6A
Authority: EP
Inventors: Ralf Wilhelm Ernst Lüngen; Thomas Willem Jumelet
Original assignee: Casthouse Revolution Center GmbH
Current assignee: Casthouse Revolution Center GmbH
Priority date: 2018-12-03
Filing date: 2019-11-22
Publication date: 2021-10-13
Also published as: CN113165057B; CN113165057A; DE102018130698A1; DE202019102883U1; US11407026B2; CA3121879A1; US20220072603A1; DE102018130698B4; WO2020114801A1

Abstract

The invention relates to a cooling system for a mould, in particular a mould for vertical continuous casting, comprising at least one cooling unit (11), wherein the mould has a running surface (10) with an inner side and an outer side and the inner side of the running surface (10a) limits a continuous casting during operation, wherein the cooling unit (11) is designed to be moveably arranged on the mould and the cooling unit (11) has an adjusting element (13), wherein the cooling unit (11) is arranged on the mould in such a way that a gap (12) is formed between the cooling unit (11) and the outer side of the running surface (10) and the width of the gap (12) can be adjusted by the adjusting element (13).

Description

Roll ingot mold for the continuous casting of aluminum and aluminum alloys

DESCRIPTION

The invention relates to a cooling system for a mold with the features of the preamble of claim 1. The invention further relates to a mold and a method for continuous casting.

A cooling system of the type mentioned is, for example, out

WO 2005/092540 Al known.

In vertical continuous casting, the melt flows continuously through a cooled, bottomless mold. The melt begins to solidify in the mold in the edge area. A so-called strand shell is formed. The strand is liquid inside. The melt is then continuously drawn off as a strand or poured off by gravity

Through the contact of the melt with the cooled mold wall, a thin shell solidifies, which encloses a "sump" and when the casting table is slowly lowered (30 to 85 mm / min.) And when the mold space is continuously topped up via a pouring channel, the direct contact between the melt and Cooling water prevented. The ingot is further cooled by direct contact between the cooling water and the ingot surface.

Critical factors must be taken into account when the mold starts up. E.g. permanent deformations, in particular "butt swell" and "butt curl", can occur due to the higher thermal conductivity of aluminum during the start-up process.

"Butt swell" refers to a thickening of the strand base compared to the rest of the strand. The mold is initially closed from below by a start-up block. The start-up block is cooled like the mold. During the start-up process, the melt flows into the mold and hits the cooled start-up block. The start block is only moved out of the mold when the mold is filled, which is why the liquid core or sump of the strand is significantly smaller during the start process than during the rest Continuous casting process. This condition results on the one hand from the lower casting speed during the start-up process and on the other hand from the additional cooling by the start-up block. The degree of shrinkage is therefore also reduced and the strand has approximately the same circumferential dimensions as the inner dimensions of the mold.

"Butt Curl" denotes a deformation at the end of the strand foot. During the start-up process, the strand, in particular the strand foot, is cooled by the mold, the starting block and the cooling water which is sprayed onto the strand at the outlet of the mold. This leads to cooling The resulting tensions are greater than the strength of the strand and cause a deformation of the strand base in the form of a convex curvature. The convex curvature additionally causes the outer sides of the strand to bend inwards. This effect causes the "butt swell" to occur more clearly. In the worst case, the temperature shock can cause cracks through which liquid metal can escape.

In order to reduce the formation of undesired deformations during continuous casting, cooling systems are used which enable targeted cooling of the strand, in particular during the start-up process.

A mold with such a cooling system is known from WO 2005/092540 A1. The mold described is used for the continuous casting of non-ferrous materials, in particular aluminum and aluminum alloys. The cooling is carried out by cooling elements which are designed as nozzles and are distributed over the circumference in the frame of the mold. The nozzles that are assigned to the central region of the strand here have a larger diameter than the nozzles that are assigned to the edge region of the strand. The bigger one

Diameter reduces the volume flow and thus the cooling in the middle area of the line. This should reduce the stresses that occur and minimize deformations.

In the example mentioned above, however, the cooling can only be controlled via the volume flow and the composition of the coolant. Other ways to control the solidification behavior and thus the

It is not intended to further minimize deformation. The deformations must be removed after the strand has completely solidified. This The process is material, cost and time consuming. The continuous casting of different aluminum alloys with a single mold of the type mentioned above is not possible, since the arrangement of the nozzles in the mold frame is adapted to the respective material to be cast and cannot be changed.

The invention is therefore based on the object of improving a cooling system of the type mentioned at the outset such that continuous casting

different materials with a mold is possible, whereby deformations that can occur during continuous casting are reduced. The invention is also based on the object of a mold with such a cooling system and a method for continuous casting with such

Specify cooling system.

According to the invention, the task is directed towards

the cooling system by the subject matter of claim 1,

the mold by the subject matter of claim 13,

- The method by the subject matter of claim 14

solved.

Specifically, the object is achieved by a cooling system for a mold, in particular a mold for vertical continuous casting, which comprises at least one cooling unit, the mold having a tread with an inside and an outside and the inside of the tread during operation

Continuous casting limited. The cooling unit is designed for movable arrangement on the mold, a gap being formed between the cooling unit and the outside of the tread and the width of the gap being determined by a

Adjustment element is adjustable.

The cooling system, which is movably arranged on the mold, provides a new, additional parameter that influences the continuous casting process. By adjusting the distance between the cooling unit, it is possible to react to changes in temperature of the running surface and the coolant. With the cooling system according to the invention it is possible that different materials, in particular different aluminum alloys, can be cast with the same mold, since the mold can be adjusted to the solidification behavior of the respective material by means of the additional parameters of the movable cooling system can. The solidification behavior of a material is specifically influenced during the start-up process. E.g. By reducing the cooling during the start-up process, the stresses in the material caused by the temperature shock can be reduced. This minimizes deformations, in particular "butt swell" and "butt curl".

Preferred embodiments of the invention are specified in the subclaims.

In one embodiment of the invention, the mold has a plurality of running surfaces, each of which is associated with a movable cooling unit, the

Circumferentially tread the continuous casting and a gap surrounding the mold is formed between the outer sides of the treads and the cooling units. The contour of the circumferential gap can be completely closed or partially open. Because each tread has its own cooling unit

Assigned adjustment element, the cooling of each tread can be set individually. Rectangular mold profiles are preferred. Alternatively, other profiles are possible. E.g. the mold can be designed as a round profile. In order to cool the tread of the round profile, several cooling units are arranged around the tread of the round profile. The cooling units can be curved or straight.

The cooling unit expediently comprises at least one means for cooling, which is arranged on the side of the cooling unit facing the outside of the tread. As a result, the cooling means is aligned with the area of the mold or strand to be cooled, and thus enables direct and efficient cooling.

It is particularly advantageous if the cooling means comprises a primary cooling means directed towards the outside of the tread and a secondary cooling means directed towards an area downstream of the mold outlet in the casting direction. This has the advantage that both the outside of the tread and the strand or the starting block can be cooled with a cooling unit. The primary coolant has the function of coolant on the outside of the tread

Apply to cool the tread and thus the melt or strand in the mold. The secondary means of cooling is after an area directed to the mold exit, where the strand leaves the mold or closes the mold at the start of the start-up block. It is conceivable that more than one cooling means is directed in each case at the mold or the strand.

The means for cooling comprises at least one elongated opening which extends at least partially along a longitudinal axis of the cooling unit and / or comprises a plurality of circular openings which are arranged at least partially along a longitudinal axis of the cooling unit. The amount of the coolant applied is influenced by the shape of the cooling means. This enables the coolant to be applied in a controlled manner to the outside of the tread and different application speeds, which can influence the solidification behavior in a targeted manner.

The cooling unit preferably comprises at least one cooling chamber with at least one inlet for coolant. This has the advantage that the coolant collects in the cooling chamber and an overpressure is formed which is evenly distributed in the cooling chamber.

The cooling chamber is preferably fluidly connected to the cooling means. The fluid connection and the uniformly distributed overpressure in the cooling chamber cause the cooling means to apply the coolant to the area to be cooled. If the same pressure acts on the means for cooling over the entire longitudinal axis of the cooling unit, the application speed and amount of the coolant mainly depends on the number and size of the openings of the means for cooling.

In a further preferred embodiment, the adjusting element comprises at least one guide, in particular a rail, on which the cooling unit is slidably mounted perpendicular to the running surface. The guide has the advantage that the cooling unit is movably mounted and it is therefore easy to change the width of the gap. The bearing on a guide or on a rail allows a good holding function to be achieved, the mobility being maintained perpendicular to the running surface assigned to the cooling unit despite large temperature fluctuations.

It is advantageous if the adjusting element comprises at least one adjusting element, in particular an adjusting screw, through which the width of the gap is adjustable. A set screw allows the stepless adjustment of the

Gap width through interaction with a tool. Alternatively, other control elements are conceivable.

The adjusting element expediently comprises at least one locking element, in particular a locking screw, which locks the cooling unit on the guide. This ensures that the gap width does not change during operation during continuous casting. Other locking elements, such as locks, are possible.

In a particularly preferred embodiment, the adjusting element comprises a control and / or a regulator and an actuator, in particular an electric servomotor, for adjusting the gap. This allows the cooling system to automatically adjust the gap width as required. In the control, the cooling system executes a predetermined behavior or a predetermined sequence. The controller compares the temperature of the tread (actual value) with a predetermined temperature value (setpoint) in real time. In the event of deviations, the temperature of the tread is changed by changing the gap width using the

Corrected actuator and / or another actuator. Other types of actuators are possible instead of the electric servomotor. For example, a pneumatic or hydraulic linear drive is conceivable as an actuator.

In addition, it is conceivable that further manipulated variables are possible that the

Temperature of the outer surface by the intervention of an appropriate one

Influence actuator. E.g. by adding additives in the coolant or by changing the casting speed of the melt.

At least one temperature sensor is advantageously arranged on the tread. The sensor enables monitoring and feedback of the temperature value of the tread in the control loop. For temperature measurement, all common methods are conceivable that are suitable for the high temperature range.

At least one temperature sensor is advantageously arranged on the cooling unit. This has the advantage that the cooling system can react to the temperature of the coolant. The coolant temperature is too high

affects the cooling effect. For temperature measurement, all common methods are conceivable that are suitable for the high temperature range. In the context of the invention, a mold with an inventive

Cooling system discloses and claims, wherein the cooling system at least partially encloses the mold in the circumferential direction.

Specifically, a mold, in particular for vertical continuous casting, is claimed, which comprises a cooling system with at least one cooling unit and a tread with an inside and an outside, the inner surface of the tread limiting continuous casting during operation. The cooling unit is movably arranged on the mold and has an adjusting element, the cooling unit being arranged on the mold in such a way that a gap is formed between the cooling unit and the outside of the tread and the width of the gap is determined by the

Adjustment element is adjustable.

Furthermore, in the context of the invention, a method for continuous casting, in particular for vertical continuous casting, with a mold according to the

Claim 14 discloses and claims. The method first comprises adjusting the gap to the width required for the material to be cast by the adjusting element. The starting block is then arranged in a starting position. Optionally, the starting block and the tread can be placed on the

required initial temperature to be cooled. Then the begins

continuous supply of melt into the mold with continuous cooling. As soon as the mold has reached a certain filling level, the start-up block is lowered, the melt being drawn through the mold. At least during the start-up phase, the process parameters are monitored and the strand is cooled in a controlled manner when it leaves the mold.

The invention is explained in more detail using several exemplary embodiments with reference to the attached schematic drawings.

Show:

Fig. 1 is a perspective view of an inventive

Embodiment of a mold with a cooling system

FIG. 2 shows a perspective view with a partially cut mold according to FIG. 1 3 shows a further perspective view with a partially cut mold according to FIG. 1

Fig. 4 is a detailed view of an embodiment of a cooling system according to the invention with an adjusting element

The cooling system comprises a cooling unit 11, which is assigned to a tread 10 with an inner side 10a and an outer side 10b and is spaced apart from the outer side 10b of the tread by a gap 12. Furthermore, the cooling system comprises an adjusting element 13, by means of which the width of the gap 12 can be adjusted.

Figure 1 shows a mold with a cooling system. The mold profile is rectangular and designed for casting slabs. It is also conceivable that the cooling system is used with other molds. The cooling system can also be used for molds with round or square profiles, e.g. for the continuous casting of round bars (billet).

The mold includes a mold entrance and a mold exit. The melt enters the mold through the mold entrance. The partially solidified melt leaves the mold again from the mold exit. The mold comprises a collar 18 which extends over the circumference of the mold in the region of the mold inlet. On the side of the collar 18 facing the mold exit, a cooling unit 11 is arranged on the longitudinal and transverse sides of the mold, which are adjustable independently of one another. The for

The mold-facing side of the collar 18 has covers 19, which are each arranged centrally on the longitudinal and transverse sides. Among the

Covers 19, the adjusting elements 13 for the cooling units 11 are arranged.

At the mold exit, a start block 17 is arranged, which is the mold

closes, ie the starting block 17 is arranged in the mold in such a way that a circumferential gap (approx. 2 mm) is formed between the inside of the tread 10a and the starting block 17, this gap being sealed by the first rapidly solidifying metal. The start-up block 17 seals the mold in the casting direction during the start-up process until the melt in the mold has reached a sufficiently high level and has solidified to such an extent that the mold exit can be opened. To do this, melt with Start-up block 17 initially pulled out of the mold. After shrinking, the further pouring takes place with the help of gravity.

In operation, the inside of the tread 10a limits the melt that is drawn through the mold and thereby extracts heat from the melt. In order to cope with the high temperatures, non-ferrous materials, molds made of special aluminum alloys and also copper alloys are used. Other materials are possible.

In order to cool the tread 10, a coolant is applied to the outside 10b of the tread, specifically sprayed or sprayed on. E.g. water can be used as a coolant. Other fluids or fluid mixtures are conceivable. The tread 10 comprises two transverse sides and two long sides. A cooling unit 11 is assigned to each of the two transverse sides and the two longitudinal sides of the tread 10b. The cooling units 11 are arranged parallel, in particular with the same shape, to the tread 10. The profile of the cooling units 11 is rectangular. There are other geometries, for example circular

Geometries, possible. The cooling units 11 comprise a cooling chamber 15 on the inside. In general, the cooling chamber 15 has a rectangular profile.

Alternatively, other shapes are also possible. The cooling chamber 15 is fluidly connected to a cooling means 14. The cooling means 14 can be designed, for example, as nozzles or bores. Other variants are possible. The means for cooling 14 is described in more detail in one of the following sections. The cooling chamber 15 has the function of collecting the coolant and guiding it into the cooling means 14. It is conceivable that the cooling unit 11 comprises a plurality of cooling chambers 15 and / or a plurality of cooling means 14.

Figures 2 and 3 are each partially sectioned representations of Figure 1. In these examples, the cooling unit 11 and the adjusting element 13 can be seen particularly well. The adjusting element 13 forms an adjustable connection between the cooling unit 11 and the mold. To protect against external influences, the adjusting element 13 is arranged under the cover 19.

The adjusting element 13 comprises a guide 16. The guide 16 is designed as a rail. Alternatively, other components that come into question as a guide 16 are conceivable. The rail extends vertically in the direction of the

Tread 10, which is assigned to the cooling unit 11. In addition there are several Guides 16 or rails possible. The cooling unit 11 is displaced on the guide 16 by a component of the adjusting element 13, such as an adjusting screw (not shown).

The adjusting element 13 can be operated manually or at least partially automated. E.g. manual adjustment can be made using the set screw (not shown) and / or a set screw (not shown). Automatic operation can be implemented by a control or regulation system (neither of which is shown). The displacement of the cooling unit, that is, the setting of the width of the gap 12, represents an additional,

influenceable parameters for cooling the mold. A small gap 12 increases the cooling effect, whereas a large gap reduces the cooling effect.

The cooling unit 11 has a holding element 20. The holding element 20 is shaped at a right angle and arranged precisely on an outer edge of the cooling unit 11. Other geometries for the holding element 20 are possible. The cooling unit 11 is movably supported on the guide 16 by the holding element 20, so that the cooling unit 11 can be displaced perpendicularly to the respectively assigned running surface 10.

FIG. 4 shows a detailed view of the cooling system in the area of the adjusting element 13. The cooling element 11 is fastened to the holding element 20. The holding element 20 is in turn movably mounted on the guide 16. A gap 12 is formed between the outside 10b of the tread and the cooling unit 11.

In this example, two means for cooling 14a, 14b are arranged on the cooling unit 11. The cooling means 14a, 14b are designed as narrow openings, each of which extends along a longitudinal axis of the cooling unit 11. The cooling means 14a, 14b are arranged on the side of the cooling unit 11 which faces the associated outside 10b of the tread. Alternatively, other shapes for the cooling means 14a, 14b are also possible. The means for cooling 14a, 14b are formed such that the coolant overcomes the gap 12 between the cooling unit 11 and the outside 10b of the tread. The cooling means 14a, 14b comprise a primary cooling means 14a and a secondary cooling means 14b. The primary cooling means 14a is on the outside 10b of the tread 10b directed and thus cools the melt that passes through the mold. The secondary means for cooling 14b is on the

Approach block 17 directed. As a result, the starting block 17 is cooled before and during the starting process. After the start-up process, the secondary cooling means 14b is no longer directed at the start-up block 17, but rather directly at the strand in order to cool it.

Reference symbol list

Tread

a Inside of the tread

b Outside of the tread

Cooling units 2x short and 2x long

gap

Adjustment element

Cooling means

a primary means of cooling

b secondary means of cooling

Cooling chamber

guide

Starting block

collar

cover

Holding element

Claims

EXPECTATIONS

1. Cooling system for a mold, in particular a mold for vertical

Continuous casting, which comprises at least one cooling unit (11), the mold having a tread (10) with an inside and an outside and the inside of the tread (10a) delimiting a continuous casting during operation,,

Because you know that

the cooling unit (11) for movable arrangement on the mold

is formed and the cooling unit (11) has an adjusting element (13), the cooling unit (11) being arranged on the mold in such a way that a gap (12) is formed between the cooling unit (11) and the outside of the tread (10) and the width of the gap (12) can be adjusted by the adjusting element (13).

2. Cooling system according to claim 1

Because you know that

the cooling unit (11) comprises at least one cooling means (14) which is arranged on the side of the cooling unit (11) facing the outside of the tread (10b).

3. Cooling system according to claim 2

Because you know that

the cooling means (14) comprises a primary cooling means (14a) facing the outside of the associated tread (10b) and a secondary cooling means (14b) facing an area facing the Mold exit is downstream in the casting direction.

4. Cooling system according to claim 2 or 3

Because you know that

the cooling means (14) comprises at least one elongated opening which extends at least partially along a longitudinal axis of the cooling unit (11) and / or comprises a plurality of circular openings are arranged at least partially along a longitudinal axis of the cooling unit (11).

5. Cooling system according to one of the preceding claims

Because you know that

the cooling unit (11) comprises at least one cooling chamber (15) which has at least one inlet for coolant.

6. Cooling system according to claim 5

Because you know that

the cooling chamber (15) is fluidly connected to the cooling means (14).

7. Cooling system according to one of the preceding claims

Because you know that

the adjusting element (13) comprises at least one guide (16), in particular a rail, on which the cooling unit (11) is slidably mounted perpendicular to the running surface (10).

8. Cooling system according to one of the preceding claims

Because you know that

the adjusting element (13) comprises at least one adjusting element, in particular an adjusting screw, through which the width of the gap (12) can be adjusted.

9. Cooling system according to claim 7 or 8

Because you know that

the adjusting element (14) comprises at least one locking element, in particular a locking screw, which locks the cooling unit (11) on the guide (16).

10. Cooling system according to one of the preceding claims

Because you know that

the adjusting element (13) comprises a control and / or a regulator and an actuator, in particular an electric servomotor, for adjusting the gap (12).

11. Cooling system according to any one of the preceding claims, characterized by the fact that

at least one temperature sensor is arranged on the running surface (10).

12. Cooling system according to one of the preceding claims

Because you know that

at least one temperature sensor is arranged on the cooling unit (11).

13. Mold with a cooling system according to one of the preceding claims, wherein the cooling system encloses the mold in the circumferential direction at least in sections.

14. A method for continuous casting, in particular vertical continuous casting, with a mold according to claim 13, comprising:

a. Adjust the gap (12) to that required for the material to be cast

Width through the adjusting element (13);

b. Arranging a starting block (17) in a starting position;

c. Optional: cooling of the starting block (17) and the tread (10) to the required initial temperature;

d. Start of the continuous supply of melt into the mold

continuous cooling;

e. Lowering the start-up block as soon as the mold has reached a certain filling level, the melt being drawn through the mold;

f. Monitoring the process parameters and controlled cooling of the strand as it emerges from the mold, at least during the start-up phase.