KR102586739B1 - Continuous casting of a metallic strand - Google Patents

Abstract

The present invention relates to a method and device for continuous casting of metal strands (1) in a continuous casting machine. The task of the present invention is to modify the known continuous casting method so that the strand 1 can be cast quickly while cavities or cracks in the strand 1 are avoided. This should increase economic efficiency and improve the internal quality of the cast strand. This problem is solved by the method according to claim 1, wherein the extraction speed v of the dummy bar 6 from the mold 2 increases after the extraction starts.

Description

CONTINUOUS CASTING OF A METALLIC STRAND}

The present invention relates to continuous casting, preferably semi-continuous casting, of metal strands in a continuous casting machine.

Specifically, the invention relates to a method for continuous casting, preferably semi-continuous, of strands in a continuous casting machine, wherein the continuous casting machine is equipped with a mold equipped with a primary cooling system, followed in the casting direction, preferably said a continuous guide with a plurality of continuous guide rollers for the guides installable on the strands and a secondary cooling system for cooling the strands, and then again with a tertiary cooling zone for controlled or regulated cooling of the strands, The method includes the following method steps:

- Inserting a dummy bar into the mold;

- fixing the dummy bar in the mold so that the head of the dummy bar fluidly seals the mold;

- initial casting by a continuous caster, in which the metal melt is filled into a mold and a casting level and a partially hardened strand are formed in the mold;

- starting extraction of a dummy bar from the mold, wherein the dummy bar is extracted from the mold at a first extraction speed (v ₁ );

- supporting and guiding the partially cured strand in a continuous guide, wherein the partially cured strand is supported and guided via continuous guide rollers and cooled by cooling nozzles of the secondary cooling system; and

- controlled or regulated cooling of the partially cured strand in a tertiary cooling zone until the strand is fully cured.

In addition, the present invention relates to a continuous casting machine for carrying out the method according to the present invention, and the continuous casting machine

- Mold with primary cooling system,

- a continuous guide with a plurality of continuous guide rollers for strand guidance and support, preferably installable on the strands, successively in the casting direction, and a secondary cooling system for cooling the strands, and

- a tertiary cooling zone for subsequent controlled or regulated cooling of the strands.

Methods and suitable devices of a similar kind are known from WO 2015/079071. A tertiary cooling zone with adjustable insulation panels allows the cooling rate of the strand to be finely adjusted from bottom to top. This prevents the formation of cavities in the strands and allows the liquid steel melt to compensate for volume changes between the solid and liquid phases caused by hardening. The internal quality of the strand is thereby significantly improved. The disadvantage in this case is that continuous casting takes a very long time until complete hardening. The specification does not detail how continuous casting can be accelerated without negatively affecting the internal quality of the strand.

The task of the present invention is to modify the known continuous casting method so that the strand can be cast quickly while cavities or cracks in the strand are avoided. This should increase economic efficiency and improve the internal quality of the cast strand.

The problem according to the present invention is solved by the subject matter of claim 1. Preferred embodiments are the subject of the dependent claims.

Specifically, it is solved by a similar type of method in which the extraction speed v of the dummy bar from the mold increases to the second extraction speed v ₂ after the start of extraction (where v ₂ > v ₁ ).

By this measure, strands with strand shells of a distinct V-shape are formed, usually steel strands or so-called superalloys (e.g. of nickel-based alloys) (https://de.wikipedia.org). A strand (see /wiki/Superlegierung) is created. In other words, the thickness of the strand shells increases rapidly in the casting direction, so that the strand shell at the bottom of the strand is significantly thicker than the strand shell at the top. This allows the liquid metal melt to directly fill the cavities caused by hardening, as a result of which the internal quality of the strand is improved. In addition, an increase in casting speed also has a beneficial effect on the economic efficiency of the continuous casting method.

In order to achieve distinct V-shaped strand shells, it is preferred if an increase in the extraction rate (v) is made with time or with strand length. By limiting the extraction speed v upwards by v _max , a situation is ensured where the strand shell at the top of the strand has a minimum thickness. Thereby openings can be prevented.

In order to prevent shock within the device, it is preferable that the extraction speed (v) increases steadily and gradually, preferably more than once.

Alternatively, the increase in extraction rate v may be non-constant, for example in discontinuous steps.

A thermal computational model is used during continuous casting.

— chemical composition of the metal melt,

- Primary cooling system in the mold,

- It is particularly advantageous to calculate the real-temperature field of the strand, including the real-phase boundaries between the solid, semi-solid and liquid phases in the strand, continuously, according to the system of secondary cooling of the strand in a continuous guide, with the dummy from the mold. The extraction speed of the bar is adjusted depending on the real-temperature field and/or real-phase boundaries, in particular depending on the real-position of the liquid phase tip.

The calculation of the real-temperature field is known for example from WO 2009/141205 A1. The details thereof are incorporated by reference into this application. According to this embodiment, the extraction speed of the dummy bar from the mold can be adjusted so that, for example, the actual position of the liquid tip corresponds as much as possible to the target position over time.

In addition to changes in extraction or casting speed during the casting process, the intensity of the cooling output of the cooling nozzles in the secondary cooling system can be adjusted depending on the real-temperature field and/or real-phase boundaries, in particular the real-position of the liquid tip. It is desirable to adjust it accordingly.

In addition, it is highly desirable to adjust the heat transfer coefficient (U) of the insulation in the tertiary cooling zone depending on the real-temperature field and/or real-phase boundaries, in particular depending on the real-position of the liquid tip.

The last two measures also have a very positive effect on the V-shape of the strand shell.

In general, it is preferred if the intensity of the cooling output of the cooling nozzles in the secondary cooling system decreases over time or strand length (s) and/or if the strands are insulated by insulation in the tertiary cooling zone, At this time, the heat transfer coefficient (U) of the insulation part increases in the casting direction. This causes the lower part of the strand, i.e. the strand head, to cool more strongly than the upper part of the strand, i.e. the strand foot.

A further improvement in the internal quality of the strand can be achieved if the continuous casting machine comprises a strand agitator movable in the casting direction, wherein the strand agitator moves the liquid tip area of the strand during extraction of the dummy bar from the mold and after the end of extraction. Stir electromagnetically.

The problem according to the invention is likewise solved by the continuous casting machine according to claim 12. Preferred embodiments are the subject of the dependent claims.

In particular, it is solved by a continuous casting machine of a similar type, which includes a control or regulation device for controlling or regulating the extraction speed v according to time or strand length during extraction of the dummy bar from the mold.

In this case, the entire tertiary cooling zone does not necessarily need to be located after the secondary cooling zone. The secondary cooling system can, for example, be achieved by a folding spray nozzle arrangement that is provided in a continuous guide during continuous casting and folded after casting. The area thus freed can be used for insulation of the strand.

It is preferred if the control or regulating device comprises a thermal computational model, which computational model can be used during continuous casting.

— chemical composition of the metal melt,

- Primary cooling system in the mold,

- Depending on the system of secondary cooling of the strand in a continuous guide, it is suitable for calculating the real-temperature field of the strand, including the real-phase boundaries between the solid, semi-solid and liquid phases in the strand continuously, while removing the dummy bar from the mold. The extraction rate can be adjusted depending on the real-temperature field and/or real-phase boundaries, in particular depending on the real-position of the liquid tip.

In addition, the intensity of the cooling output of the cooling nozzles in the secondary cooling system and/or the heat transfer coefficient (U) of the insulation in the tertiary cooling zone depends on the real-temperature field and/or the real-phase boundaries, in particular that of the liquid tip. It is desirable if it can be adjusted according to the actual-position.

Additional advantages and features of the invention are given from the description of non-limiting embodiments.
1A to 1H represent method steps in execution of the method;
Figure 2a shows a continuously cast strand according to the prior art,
Figure 2b shows a continuously cast strand produced according to the invention;
Figure 3a shows a curve of the rate of extraction of strands from the mold over time t;
Figure 3b shows a curve of the rate of extraction of a strand from the mold over the strand length (s);
Figure 4a shows a curve of the flow rate (Q) of coolant through a cooling nozzle over time (t);
Figure 4b shows a curve of the flow rate (Q) of coolant through a cooling nozzle over the strand length (s);
5 is a diagram of the amount of coolant accumulated on the strand;
Figure 6 is a diagram of the variable insulation in the tertiary cooling zone;
Figure 7a is a diagram of variable insulation in the tertiary cooling zone by pivotable insulation flaps;
Figure 7b is a diagram of variable insulation in the tertiary cooling zone by movable insulation flaps;
Figure 8a is a diagram of a continuous casting machine according to the invention with control and regulation devices for regulation of the extraction speed (v),
Figure 8b is a view of a continuous casting machine according to the invention with control and regulation devices for regulating the intensity of the secondary cooling system,
Figure 8c is a view of a continuous casting machine according to the invention with control and regulation devices for regulating the insulation in the tertiary cooling zone;
9A to 9E are diagrams of method steps of an alternative continuous caster to FIGS. 1A to 1H;
Figure 10 is a view of the head insulation, and
Figure 11 is a plot of the position of a liquid tip in a strand over time, according to the prior art and the present invention.

1a to 1h show the continuous casting of strands 1 made of steel, specifically the so-called semi-continuous continuous casting. The continuous casting machine is formed as a vertical device and has a secondary cooling system ( 4), and a tertiary cooling zone (5) with an insulating section (9) and a plurality of insulating plates (9a). The head of the continuous casting machine comprising the mold 2 and the continuous guide 3 is movable with respect to the tertiary cooling zone 5, so that only one head can provide strands in multiple tertiary cooling zones. can provide them. The continuous guide rollers 3a do not necessarily have to be installable on the strand 1 via an actuator. It is sufficient that such continuous guide rollers are mechanically installable, for example via washers or so-called shims.

Figure 1a shows the situation before initial casting in a continuous caster. As the dummy bar 6 is inserted into the mold 2, the stationary dummy bar 6 consequently seals the mold 2 in a fluid-tight manner in the casting direction G.

Figure 1b shows initial casting in a continuous caster. The steel melt or the melt of the so-called superalloy is fed directly into the mold 2 or through a distributor vessel, resulting in a casting level M in the mold 2 and the primary cooling system of the mold 2 forming a strand ( 1) is formed. After a more or less constant casting level M has been established, extraction of the dummy bar 6 from the mold 2 begins. Initially, extraction takes place relatively slowly, with a first extraction speed (v ₁ ) of 0.12 m/min (see Figure 3a). The extraction rate v is increased according to the invention (see Figure 3a), resulting in the formation of a strand 1 with distinct V-shaped strand shells (see Figure 2b). In contrast, in the continuous casting method according to the prior art (see Figure 2a) the strand 1 does not have a distinct V shape, which leads to poor internal quality (cracks, cavities, etc.). The distinct V-shaped strand shells 11 of the strand 1 (see Figure 2b) allow the strand 1 to separate from the upper region of the partially hardened strand 1b during cooling in the tertiary cooling zone 5. Being able to re-absorb the liquid melt results in the cavities or cracks, as the case may be, caused by hardening being refilled by the melt. The thin strand shell 11 at the upper strand end 1c significantly facilitates this. The mold 2 vibrates in the vertical direction by an oscillator not shown. A stirring coil, also not shown, beneath the mold 2 agitates the partially cured strand. Both details are customary in the field and are known for example from WO 2015/079071.

In Figure 1c continuous casting continues, where the strand 1 is supported and guided by continuous guide rollers 3a in the continuous guide 3 and the cooling nozzles 4a of the secondary cooling system 4. ) is further cooled by. According to the solid line in Figure 3A, the extraction speed at the time point in Figure 1C is approximately 0.2 m/min.

Figure 1d shows a point in continuous casting where the supply of steel melt into the mold has just been stopped. The extraction speed v corresponds to a second extraction speed v ₂ of 0.36 m/min. This extraction rate of strand 1 is maintained until the end of the extraction process (see Figure 3a).

After the supply of steel melt is stopped, the casting level (G) falls within the mold (2) (see Figure 1e). At this point the strand 1 typically has a strand length L of 6 to 12 m. The diameter of the strand 1 is 600 mm.

Figure 1f shows the situation after the strand end 1c has passed the continuous guide 3 and the secondary cooling system 4 has been switched off. The partially cured strand (1b) is then placed in the tertiary cooling zone (5), where it is slowly, controlled or controlled cooled.

Figures 1g and 1h show the cooling of the partially cured strand 1b in the tertiary cooling zone 5, with the time point in Figure 1g preceding the time point in Figure 1h. As already specified above, the continuous caster head can operate a number of tertiary cooling zones (5) and can move, for example horizontally, into further tertiary cooling zones (5). To further delay the hardening of the strand end 1c, the strand end 1c can be heated by a head heater 13 instead of the secondary cooling system 4. The head heater 13 can be formed, for example, by induction or by means of an exothermic powder (this method is written in English as "hot topping"), wherein the powder generates heat energy together with the liquid steel melt. Occurs. Since the partially cured strand 1b is particularly susceptible to the formation of cracks or cavities in the liquid tip region, it is advantageous if the strand stirrer 14 particularly electromagnetically agitates this region.

Figure 2a shows a continuously cast partially cured strand (1b) according to the prior art. The strand ends are almost completely hardened, with the result that any cavities or cracks in the strand can no longer be filled by the liquid melt 12 .

In contrast, Figure 2b shows a strand according to the invention. The strand end 1c is still generally in a liquid state, with the result that any cavities or cracks within the strand can be filled by the liquid melt 12 . The strand thereby has better internal quality.

As cited above, Figure 3a shows the extraction rate (v) over time (t). The diagram illustrates the fact that the extraction rate (v) does not necessarily have to rise linearly, but rather may rise, for example, sublinear or superlinear (see dashed lines). Rising in discrete steps, not shown, may also be considered and desirable.

Figure 3b shows a further diagram of the extraction rate (v), where v depends on the strand length (s) and not on time (t). This ensures that the strand beginning 1a cools more strongly than the strand end 1c, irrespective of any interruptions in the casting process.

In both cases, increasing the extraction rate (v) not only increases the internal quality of the strand (1), but also improves the economic efficiency of the continuous casting method, since more strands can be cast in the same time. Because.

The internal quality of the strand can also be achieved by adjusting the intensity of the secondary cooling system 4 (see Figure 1c) depending on time or strand length (s). In both cases this means that in the secondary cooling system 4 the strand beginning 1a is cooled more strongly than the strand end 1c. This measure can be taken in addition to or instead of increasing the extraction speed v of the dummy bar 6 from the mold 2 .

For the case where the intensity adjustment of the secondary cooling system 4 is additionally made to changes in the extraction rate v, the description of FIGS. 1a to 1h continues to apply fully. In addition to this, the intensity of the secondary cooling system changes depending on time (t) or strand length (s). The change in intensity over time of the secondary cooling system 4 due to a change in the flow rate Q through the cooling nozzles 4a of the secondary cooling system 4 is shown in Figure 4a. The reduction of the flow rate Q or the intensity of the secondary cooling system 4 can be linear (solid line), but also sublinear or superlinear (see dashed line). Alternatively, the strength of the secondary cooling system may vary depending on the strand length (s) (see Figure 4b). In this case the strand length s is detected or calculated during casting and the strength of the secondary cooling system 4 is adjusted according to the characteristic curve in Figure 4b.

For cases where the intensity adjustment of the secondary cooling system 4 is made instead of changing the extraction rate v, the description of FIGS. 1a to 1h should be modified so that the extraction rate v is kept constant. The strand 1 extracted from the mold 2 is cooled in the secondary cooling system 4 with varying intensity depending on time or strand length, so that the strand start 1a is stronger than the strand end 1c. It cools down.

Figure 5 schematically shows the amount of coolant accumulated on different regions of the partially cured strand 1b when adjusting the intensity of the secondary cooling system with time or strand length (see Figure 4a or 4b). . A large amount of coolant accumulated, as at the beginning of the lower strand (1a), is shown in a fine grid, and a small amount of coolant accumulated, as in the upper strand end (1c), is shown in a coarse grid. By changing the flow rate of the coolant (Q) with time or with the strand length, or with the pressure (p) with time or with the strand length, the intensity of the secondary cooling system changes, resulting in the beginning of the strand cooling more strongly than the end of the strand. do.

In Figure 6 further possibilities for improving the internal quality of the strands are presented. In this case, the insulation portion (9) in the tertiary cooling zone (5) is adjusted according to the strand length (L), and the heat transfer coefficient (U) of the insulation portion (9) increases in the casting direction (G). . In other words, in the tertiary cooling system 5 the strand beginning 1a is cooled more intensely than the strand end 1c. This measure can be taken in addition to or instead of increasing the extraction speed v of the dummy bar 6 from the mold 2 . Additionally, modifications to the insulation 9 in the tertiary cooling zone 5 can be made in addition to, or instead of, adjusting the intensity of the secondary cooling system 4 . The change in the heat transfer coefficient U of the insulation 9 is shown in Figure 6 by the variable thickness of the insulation.

Figure 7a shows the variation of the strand length of the insulation 9 in the tertiary cooling zone 5 by the insulation plates 9a. In order to cool the strand beginning 1a more intensely than the strand end 1c, the pivotable flaps of the insulation plates are adjusted differently, with the upper flaps generally closed and the lower flaps generally open. As a result, the heat transfer coefficient (U) of the insulation portion (9) increases in the casting direction (G). The change in the opening angle of the flaps can be preset statically or dynamically during cooling in the tertiary cooling zone 5 , for example via a swing drive that swings the flaps.

Figure 7b shows an alternative to Figure 7a, where the coverage ratio of the insulating flaps 9a of the strand is higher at the end of the strand 1c than at the beginning of the strand. As a result, the heat transfer coefficient (U) of the insulation portion (9) increases in the casting direction (G).

Figure 8a shows a continuous casting machine according to the invention with a control or regulation device 10 for controlling or regulating the extraction speed v. The control or regulation device (10) takes into account the chemical composition (15) of the metal melt, the primary cooling system (2a) in the mold (2), the secondary cooling system (4) and the strand length (s). The temperature field and liquid tip within the strand 1 are calculated and the extraction speed of the motor 16 is adjusted according to the liquid tip. Optionally, it is likewise possible to take into account additional parameters, such as the position of the insulation plates 9a in the tertiary cooling zone.

Figure 8b shows a continuous casting machine not according to the invention with a control or regulation device 10 for controlling or regulating the intensity of the secondary cooling system 4 depending on the strand length s. The control or regulation device 10 controls the temperature field and liquid tip in the cast strand 1 taking into account the chemical composition 15 of the metal melt, the primary cooling system 2a in the mold and the strand length s. Calculate and adjust the intensity of the secondary cooling system 4 according to the liquid tip. The liquid tip is calculated in real time in a thermal computational model.

Figure 8c likewise shows a continuous casting machine not according to the invention with a control or regulation device 10 for controlling or regulating the heat transfer coefficient U of the insulation 9 in the tertiary cooling zone 5. The control or regulation device 10 calculates the temperature field and the liquid tip in the cast strand 1 taking into account the chemical composition 15 of the metal melt and the primary cooling system 2a in the mold and determines the temperature field and liquid tip in the insulating plates 9a. ) is adjusted according to the liquid tip. The liquid tip is calculated in real time in a thermal computational model.

Figures 9a to 9e show an alternative continuous casting machine for carrying out the method according to the invention. In Figure 9a, strand 1 is cast in mold 2 and extracted from said mold with a variable extraction rate v. The strands (1) are supported and guided within continuous guides (3) and cooled by a secondary cooling system. In Figure 9b, casting in the mold has been completed and the strand 1 is located within a radiating region 17, within which the strand can radiate heat to the surroundings over a certain period of time. On its way to the tertiary cooling zone 5, the strand passes through a stirring coil 14 and is electromagnetically stirred by this stirring coil (see Figure 9c). The strand is then provided into the tertiary cooling zone (5), where it is cooled under control or regulation by the thermal insulation (9). In particular, since the strand ends 1c are very sensitive, these strand ends are again insulated by the cover (see FIGS. 9d and 9e).

In Figure 10 the head insulation 18 of the strand 1 is schematically presented. The head insulation includes an insulation 9 for the strand end 1c of the strand 1, and as a result the strand end 1c remains in a liquid state for longer. In addition to the insulation 9, a pyrogenic powder 19 can be provided on the liquid strand end 1c, which further heats the strand 1.

Figure 11 schematically shows the results of adjusting the extraction rate (v) according to time or path and/or controlling the intensity of the secondary cooling system according to time or path and/or adjusting the heat transfer coefficient (U) of the insulation portion (9). It is shown as All of these measures have the effect of retarding the curing of the partially cured strand (see dashed lines indicating the position of the liquid tip within the strand over time). In contrast, solid lines indicate comparative examples based on prior art. As cited above, these measures allow the strand according to the invention to have a distinct V-shaped strand shell, unlike the strands according to the prior art (see left side of Figure 11), which do not have a distinct V-shaped strand shell (see Figure 11, left). 11 see right).

Although the present invention has been described and described in more detail by way of detailed preferred embodiments, the present invention is not limited by the known examples, and other modifications can be made thereto without departing from the protection scope of the present invention. Examples can be derived by those skilled in the art.

1 strand
1a strand start
1b partially cured strand
1c strand end
2 mold
2a primary cooling system
3 consecutive guides
3a continuous guide rollers
4 Secondary cooling system, secondary cooling zone
4a cooling nozzle
5 Tertiary cooling system, tertiary cooling zone
6 dummy bar
7 Computational model
8 liquid tips
9 Insulation section
9a insulation board
10 Control or regulating device
11 strand shell
Liquid region of 12 strands
13 head heater
14 Strand Agitator
15 Chemical composition
16 motor
17 divergence area
18 head insulation
19 pyrogenic powder
G casting direction
L strand length
M casting level
Q flow rate
S strand length
t time
U heat transfer coefficient
v Extraction speed, casting speed

Claims (14)

As a method for semi-continuous casting of strand (1) in a continuous casting machine,
The continuous casting machine consists of a mold 2 equipped with a primary cooler 2a, followed in the casting direction G, with a plurality of strand guiding rollers 3a for guidance and 2 for cooling the strand 1. a strand guide (3) with a secondary cooler (4), and again subsequently a tertiary cooling zone (5) for controlled or regulated cooling of the strand (1), the method comprising the following method steps: :
Inserting a dummy bar (6) into the mold (2);
maintaining the dummy bar (6) within the mold (2) such that the head of the dummy bar (6) fluidly seals the mold (2);
Starting casting in a continuous casting machine - the metal melt is cast into a mold (2) and a casting level (M) and a partially hardened strand (1b) are formed in the mold (2);
Starting the extraction of the dummy bar (6) from the mold (2), wherein the dummy bar (6) is extracted from the mold (2) by a first extraction speed (v ₁ );
Supporting and guiding a partially cured strand (1b) in a strand guide (3) - the partially cured strand (1b) is supported and guided by strand guide rollers (3a), and a secondary cooler (4) ) is cooled by cooling nozzles 4a - ;
carrying out controlled or regulated cooling of the partially cured strand (1b) through a tertiary cooling zone (5) until the strand (1) is fully cured;
After starting the extraction, the extraction speed v of the dummy bar 6 from the mold 2 increases to the second extraction speed v ₂ , and v ₂ > v ₁ , and
During semi-continuous casting, the thermal computational model
Chemical composition of metal melt (15);
Primary cooler (2a) in mold (2),
According to the secondary cooler (4) of the strand (1) in the strand guide (3), the real-temperature distribution of the strand (1), including the real-phase boundaries between the solid, semi-solid and liquid phases in the strand (1). Continuously calculating,
The extraction speed v at which the dummy bar 6 is extracted from the mold 2 is set depending on the real-temperature distribution, real-phase boundaries, and/or the actual position of the liquid tip 8. Characterized by,
Method for semi-continuous casting of strands in a continuous casting machine. According to clause 1,
Characterized in that the extraction rate (v) increases with time (t) or strand length (s),
Method for semi-continuous casting of strands in a continuous casting machine. According to clause 2,
Characterized in that the extraction rate (v) is continuously increased in some parts,
Method for semi-continuous casting of strands in a continuous casting machine. According to clause 2,
Characterized in that the extraction rate (v) increases discontinuously,
Method for semi-continuous casting of strands in a continuous casting machine. According to clause 1,
The extraction speed (v) of the dummy bar (6) is set so that the actual position of the liquid tip (8) corresponds as much as possible to the target position over time of the liquid tip (8),
Method for semi-continuous casting of strands in a continuous casting machine. According to claim 1 or 5,
Characterized in that the intensity of the secondary cooler (4) is adjusted depending on the real-temperature distribution, real-phase boundaries and/or the actual position of the liquid tip (8).
Method for semi-continuous casting of strands in a continuous casting machine. According to claim 1 or 5,
The strand (1) is insulated by the insulation portion (9) in the tertiary cooler (5),
Characterized in that the heat transfer coefficient (U) of the insulation (9) is set depending on the real-temperature field, the real-phase boundaries and/or the actual position of the liquid tip (8).
Method for semi-continuous casting of strands in a continuous casting machine. According to any one of claims 1 to 5,
Characterized in that the strength of the secondary cooler (4) decreases over time (t) or strand length (s).
Method for semi-continuous casting of strands in a continuous casting machine. According to any one of claims 1 to 5,
The strand (1) is insulated by the insulation portion (9) in the tertiary cooler (5),
Characterized in that the heat transfer coefficient (U) of the insulation portion (9) increases in the casting direction (G),
Method for semi-continuous casting of strands in a continuous casting machine. According to any one of claims 1 to 5,
The continuous casting machine includes a strand agitator (14) movable in the casting direction (G),
Characterized in that the strand stirrer (14) electromagnetically stirs the area of the liquid tip (8) of the strand (1) during extraction of the dummy bar (6) from the mold (2) and after the end of extraction.
Method for semi-continuous casting of strands in a continuous casting machine. delete delete delete delete

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