EP0592360B1 - Machine for vertical continuous casting in a magnetic field - Google Patents

Abstract

In the mould (10), the casting machine has a baffle plate (66) with a lower guide surface (80) for the cooling water (20) sprayed on at high pressure and/or has a supporting plate with an upper guide surface for cooling water (20) flowing out at low pressure. Both guide surfaces consist of an insulating material. The electromagnetic screening (18, 76) is cooled on the inside at least in the active area. The mould housing (32) preferably consists of a perforated sheet (34) bent several times. The active area of the screening is preferably designed as a U- or V-shaped screening sheet with an insert or a coating to attenuate the magnetic effect of the inductor (12) to an increasing extent from the bottom towards the top. The guide surface (80) upon which the water impinges is displaced and/or swung backwards and forwards continuously in a predetermined rhythm. The water curtain (22), which is independent of the electromagnetic screening (18), is thereby moved upwards and downwards on the strand (14) over a height (h). <IMAGE>

Description

The invention relates to a casting machine according to the preamble of claim 1. The invention further relates to a method for cooling a Stranges in a casting machine.

For continuous casting processes, also continuous casting processes are called metals in the form of several meters long Ingots or bolts cast, which are used as primary material for various subsequent processing steps are used such as for pressing, rolling or forging.

The most important link in a continuous casting machine are molds, which in conventional processes cross-section the the cast strand. A casting machine is, ever according to the number of cast strands, with accordingly equipped with many lowerable approach floors, which are fixed are connected to a casting table.

As the molds slowly fill with the melt, the metal begins to solidify on the approach floors. This are cooled and lowered at such a speed that the solidus line of solidifying metal always remains within the mold frame. The strands the solidification of which is accelerated by water cooling, grow down to the same extent as the approach floors be lowered. Within a given length of a The casting process is uninterrupted.

The most important parameters of continuous casting include a properly controlled lowering speed as well as the Cooling the metal in the right place and with the right one Intensity. These parameters have a strong impact on the surface of the ingot. With poor control the parameters can segregation, leakage of melt through the frozen shell, tearing or lime binding occur.

That has only recently been brought to industrial maturity Magnetic field casting (EMC) is based on complete elimination mechanical contact between the mold and the solidifying metal. The liquid metal is through controllable electromagnetic forces exactly in the cross-sectional shape of the strand kept.

The EMC process can not only be a homogeneous internal Structure, but also a smooth surface of the cast Achieve metal, resulting in better physical and chemical properties of the press or forged bolts as well as rolled bars. Costly post-treatments, such as the removal of the surface skin or the edge bumping, are no longer necessary with the EMC process.

The starting phase is very important in magnetic field casting because the solidification front in a narrow height range of the mold of about 10 mm. This is necessary because at an EMC mold the magnetic forces the metallostatic Compensate for melt pressure above the solidification front have to. That is why complete control is required cooling, especially during the start-up phase, essential. The lowering speed and the cooling a certain alloy and ingot dimensions be optimized based on time.

• Mit der Verwendung von kohlendioxidhaltigem Kühlwasser kann die Kühlintensität um einen Faktor bis etwa 5 gesenkt werden. Die Verwendung von CO₂-haltigem Kühlwasser bringt jedoch auch Nachteile mit sich. Das Kohlendioxid muss in Druckflaschen abgefüllt, transportiert und gelagert werden. Weiter muss CO₂-haltiges Kühlwasser bis kurz vor dem Austritt unter hohem Druck gehalten werden, was konstruktiv und werkstoffmässig zu einem höheren Aufwand führt.
• Nach einer weiteren Variante wird wenigstens während der Startphase des Giessens pulsierend Kühlwasser aufgespritzt. Dieses Verfahren hat sich beispielsweise beim Giessen der meisten Aluminiumlegierungen bewährt, bei harten Legierungen können jedoch Haarrisse entstehen.

Bar curvature and local cracking can be largely eliminated if the shock effect and the intensity of the cooling water can be reduced:

• With the use of carbon dioxide-containing cooling water, the cooling intensity can be reduced by a factor of up to about 5. However, the use of CO ₂ -containing cooling water also has disadvantages. The carbon dioxide has to be filled, transported and stored in pressure bottles. Furthermore, CO ₂ -containing cooling water has to be kept under high pressure until shortly before the outlet, which leads to higher expenditure in terms of construction and materials.
• According to a further variant, cooling water is pulsed on at least during the starting phase of the casting. This method has proven itself, for example, when casting most aluminum alloys, but hairline cracks can occur with hard alloys.

• Das aus nichtrostendem Stahl, insbesondere INOX, bestehende Material der Abschirmung absorbiert die den Strang formenden elektromagnetischen Kräfte in gleichem Masse zunehmend, wie das Material zunimmt. Dies führt zu einer zusätzlichen Erwärmung.
• Die polierte Aussenfläche einer Abschrägung der Abschirmung wirkt zugleich als Leitfläche für das Kühlwasser, wobei auf der Leitfläche vorerst ein Kühlwasserfilm, dann ein auf den Strang aufspritzender Wasservorhang gebildet wird. Als Nebenwirkung wird die elektromagnetische Abschirmung durch das auftreffende Wasser gekühlt. INOX beispielsweise ist ein ausgesprochen schlechter thermischer Leiter.

The downward wedge-shaped electromagnetic shielding of known molds for EMC casting machines simultaneously fulfills two functions:

• The shielding material made of stainless steel, in particular INOX, increasingly absorbs the electromagnetic forces that form the strand to the same extent as the material increases. This leads to additional warming.
• The polished outer surface of a bevel of the shield also acts as a guide surface for the cooling water, a cooling water film being formed first on the guide surface, then a water curtain spraying onto the strand. As a side effect, the electromagnetic shield is cooled by the water that hits it. INOX, for example, is an extremely poor thermal conductor.

• Auf der polierten Aussenseite der elektromagnetischen Abschirmung, der Leitfläche, lagert sich Kalk ab und führt zu einer ungenügenden Filmbildung durch das Kühlwasser und zu schwachen Kühlung der Abschirmung. Da diese Kühlung hinreichend sein muss, sind aufwendige Unterhaltskosten unumgänglich.
• Die elektromagnetische Abschirmung ist starr an der Kokille befestigt, die Lage der Leitfläche kann also nicht verändert werden.
• Die Bestandteile der Kokille bestehen aus Aluminium, Eisen und Kupfer, was zu Korrosionsproblemen führt.

This results in some problems for known EMC molds:

• Lime deposits on the polished outside of the electromagnetic shield, the guiding surface, and leads to insufficient film formation by the cooling water and weak cooling of the shield. Since this cooling must be sufficient, expensive maintenance costs are unavoidable.
• The electromagnetic shield is rigidly attached to the mold, so the position of the guide surface cannot be changed.
• The components of the mold consist of aluminum, iron and copper, which leads to corrosion problems.

A casting machine of the type mentioned at the outset is known from EP-A-0229589 known. A vertically displaceable counter screen is cooled inside. The one used for internal cooling Cooling water emerges from the counter screen through coolant passages and is directed to the strand. By the shift of the counter screen also changes the impact height this additionally coolant jets directed onto the strand. The bulk of the coolant is passed through a the shield trained guide surface directed to the strand. The amount of coolant applied to the strand can in this case via dielectric intermediate pieces or Coolant chicanes are regulated.

EP-A-0372947 discloses a conventional continuous casting mold with a swivel deflector for the Coolant for changing the impact height of the coolant on the strand.

The inventors set themselves the task of a casting machine of the type mentioned at the beginning, which thanks simpler design and less electromagnetic losses Energy of the molds in relation to both Manufacturing and operating costs more economical is. The mold should be flexible in the application of cooling water and be cooled with a process that is more gentle can be applied as previous.

With regard to the casting machine, the object is achieved according to the invention solved by the features of claim 1. Special and continuing education Embodiments of the casting machine are the subject of dependent claims.

According to a particularly advantageous embodiment of the invention the mold housing consists of a expediently about 3 mm thick perforated plate. This means compared to the known State of the art in economic and technical In terms of a huge advance, the expensive metallic Moldings, which are solid and in the Usually made of aluminum, can be through a sheet metal housing made of stainless steel, the same material as the shield, be made. Because of the large amounts enforced Cooling medium can plastic molded parts in the Sheet metal housings are used, which is machining technology and also brings huge advantages in terms of costs. Moreover the corrosion problems mentioned above become completely eliminated.

Further advantages of the chamfered mold housing are in that the loss of electromagnetic energy is less is and the largely one-piece embodiment no sealing problems occur.

The one consisting of an insulating material according to the invention Guide surface for the cooling water of the mold is preferred the surface of a separately and appropriately replaceable used baffle. The constant intense Cooling allows production from plastic, which is also a technically simple and extremely cheap Embodiment is. The baffle is preferred slidable and / or pivotable. The baffle can be in their position adjusted by means known per se will. The cooling water hitting in an unchangeable direction can be redirected in a certain angular range will. In other words, the impact height is on this Guide surface formed, sprayed on the strand curtain adjustable, for example over a range of 5 to 20 mm with non-adjustable mold height.

This means compared to the deflection of the cooling water a guide surface of the magnetic shield, which is rigid is a significant advance. The cooling one Water curtains can be applied there with simple means where it can really have an optimal effect.

The uniform formation of a water film on the guide surface the baffle can be improved that longitudinal grooves are formed. Under longitudinal the direction of flow of the cooling water is understood here.

Hard aluminum alloys, for example, become lower Lowering speed is poured, doing so less cooling water needed. In contrast to the impact a lot of water with a relatively high pressure the guiding surface, where a largely even water film is formed, the water hits with smaller amounts of coolant with too little pressure on the guide surface Cooling water runs off without film formation and can on the anyway even sensitive strands do not have an optimal cooling effect unfold. In the mold can therefore under the baffle or a support plate under the emerging cooling water be formed, which is longer compared to the baffle is trained, i.e. leads closer to the strand.

The cooling water is sprayed onto the support plate, with less The baffle of the baffle becomes little or no pressure not wetted. The surface facing the baffle the one made of the same material as the baffle Support plate is also used as a guide surface for cooling water educated. This is preferably interchangeable like the baffle Carrier plate is also preferably displaceable and / or swiveling, expediently with the same Drive elements such as the baffle. Only with a moving one Carrier plate can be the level of the hitting the strand Cooling water curtain can be varied.

The support plate can have holes in sensitive metal strands or have slots for draining cooling water. Because the cooling water discharged in this way never on the hot strand hits, the cooling effect can be further reduced.

Although the deflection and the support plate at least partially between the inductor and the electromagnetic shield are arranged, they can not by the electromagnetic Heat exposure, they consist of one insulating material, preferably made of plastic, for example Polyethylene or polypropylene. In any case the limescale formation is significantly lower than on a guide surface a previously known type of shielding.

In the active area of the inductor is U-shaped or V-shaped bent, through which cooling water flows, i.e. internally cooled Shielding plate arranged, which like the outside of the active area of the inductor preferably consists of stainless steel. The preferred consisting of approximately 1 to 2 mm thick, INOX sheets, shielding closed on the side only acts as functional Part if an insert or coating is made a better electromagnetic shielding material is. Otherwise the bent sheet is made of stainless steel a pure protective and carrier function.

Known shields from EMC molds are also in the lowest Massively formed area, they run as mentioned wedge-shaped. As a result, with a large amount of material and External cooling is a shield that increases from bottom to top achieved how this meets the requirements of EMC continuous casting corresponds.

• Das U- oder V-förmig umzubiegende Blech aus nichtrostendem Stahl wird bevorzugt mit Silber oder Kupfer beschichtet und dann mit dieser Schicht nach innen umgebogen. Das Beschichten erfolgt mit üblichen Verfahren, beispielsweise galvanisch, chemischer Abscheidung aus der Gasphase, Aufspritzen, Abscheidung aus einem Plasma.
• Das U- oder V-förmige Blech wird nach dem Umbiegen entsprechend beschichtet.
• Wenigstens eine Folie oder ein Blech aus Silber, Kupfer oder Messing, wird in das U- oder V-förmige Blech eingelegt. Diese Folie oder dieses Blech kann umgebogen, gefaltet oder mehrschichtig ausgebildet sein, wobei eine Abstufung oder eine kontinuierliche Dickenveränderung in der Weise erfolgt, dass die Abschirmung von unten nach oben stufenweise oder kontinuierlich zunimmt.

According to the embodiment of the mold according to the invention, an insert or coating in the U-shaped or V-shaped part of the shield increasingly weakens the electromagnetic action of the inductor in the upward direction. This stepwise or continuously increasing electromagnetic shielding is achieved, for example, by the following measures:

• The U or V-shaped sheet of stainless steel to be bent is preferably coated with silver or copper and then bent inwards with this layer. Coating is carried out using customary methods, for example galvanic, chemical deposition from the gas phase, spraying, deposition from a plasma.
• The U-shaped or V-shaped sheet is coated accordingly after the bending.
• At least one foil or sheet made of silver, copper or brass is placed in the U- or V-shaped sheet. This film or sheet can be bent, folded or multilayered, with a gradation or a continuous change in thickness in such a way that the shield increases step by step or continuously from bottom to top.

By inserting a foil or sheet on the one hand or a coating on the other hand from one of the mentioned Metals can shield against the bent steel sheet can be multiplied by depending on the material and thickness a factor of several hundred.

A silver insert or coating is advisable 0.05 to 0.2 mm thick, made of copper 0.2 to 0.4 mm and made of brass 0.5 to 2 mm, according to the specific absorbency, the thickness of this layer being continuous or can gradually increase from bottom to top.

With regard to the method of cooling a strand in one Casting machine in which the cooling water at an acute angle sprayed onto a guide surface, a regular film of water is formed and sprayed onto the strand, the stands out Solution of the task according to the invention characterized in that the water-loaded guide surface continuously in a predetermined Rhythm shifted back and forth and / or panned and thereby the Water curtain on the strand over a certain height is moved up and down. Special and continuing education Embodiments of the method are the subject of dependent claims.

With the method according to the invention, the advantages exploited and improved pulsating water cooling by making the relatively hard transition from "cooling" to "non-cooling" continuously in a strongly tempered form occurs. So even with sensitive alloys, such as hard aluminum alloys, hairline cracks be avoided.

In terms of timing, the water is applied Guide surface preferably moved sinusoidally, in particular with a time period of 1 to 3 seconds per half wave. The curtain of water on the line is preferred an up and down movement of 5 to 20 mm. In itself in a known manner, the movement of the water-loaded takes place Guide surface preferably with pneumatic, hydraulic or electromagnetic drive, from a microprocessor controlled.

The cooling water is expedient with constant, in Sprayed in the range of 0.01 to 0.5 bar, beginning with the lowering of the approach floor, which is about 0 to 3 min after the start of pouring. Because especially the Starting phase is critical, moving the water-loaded Guide surface, while in practice mostly 3 to 7 min. Of course, moving the guide surface only set if this is sensitivity of the alloy.

The strand can be electromagnetic during cooling be vibrated, especially continuously.

• Durch eine vom Magnetfeld nicht erwärmte, wasserbeaufschlagte Leitfläche wird die Abscheidung von Kalk auf der polierten Oberfläche der Abschirmung vermieden und dadurch die Unterhaltskosten entsprechend herabgesetzt.
• Durch eine einstellbare wasserbeaufschlagte Leitfläche kann das Niveau des Kühlwasservorhangs auf den Strang eingestellt werden.
• Wenigstens in der Anfahrphase und/oder bei empfindlichen Legierungen kann der Wasservorhang in einem einstellbaren Rhythmus gehoben und gesenkt werden. Die Pulswasserkühlung wird verfeinert, indem die Schockwirkung der plötzlichen Wasserzugabe eliminiert und dauernd Kühlwasser auf den Strang geführt wird. Dadurch entstehen keine kurzzeitigen Ueberhitzungen.
• Die Zugabe von CO₂, welche beim EMC-Stranggiessen üblich ist, entfällt.
• Durch die Ausbildung eines abgekanteten Kokillengehäuses aus nichtrostendem Stahlblech, dem gleichen Material wie die elektromagnetische Abschirmung, entfallen Korrosionsprobleme.

The advantages achieved with the invention can be summarized as follows:

• The deposition of lime on the polished surface of the shield is avoided by a guide surface that is not warmed by the magnetic field and the maintenance costs are reduced accordingly.
• The level of the cooling water curtain can be adjusted to the strand by means of an adjustable water-bearing guide surface.
• At least in the start-up phase and / or with sensitive alloys, the water curtain can be raised and lowered in an adjustable rhythm. Pulse water cooling is refined by eliminating the shock effect of the sudden addition of water and continuously supplying cooling water to the line. As a result, there are no short-term overheating.
• The addition of CO ₂ , which is common in continuous EMC casting, is eliminated.
• Corrosion problems are eliminated by forming a bent mold housing made of stainless steel, the same material as the electromagnetic shielding.

The inventive design of the mold housing than from a sheet, especially from a Perforated sheet made of stainless steel is not inevitable to the guide surface for the cooling water and the internally cooled Shield bound, just as little as that of the active Area of electromagnetic shielding in the form of a U or V-shaped sheet made of stainless steel an insert or coating.

- Fig. 1

eine den Stand der Technik darstellende, in eine Giessmaschine eingesetzte EMC-Kokille,

- Fig. 2

eine Teilansicht eines Lochblechs für ein Kokillengehäuse,

- Fig. 3

einen Schnitt durch eine Kokille in Längsrichtung des Stranges,

- Fig. 4

eine Variante von Fig. 3,

- Fig. 5

den aktiven Teil einer elektromagnetischen Abschirmung,

- Fig. 6

einen Teilschnitt durch einen Schenkel einer Fig. 5 entsprechenden elektromagnetischen Abschirmung,

- Fig. 7

ein Einlageblech für eine elektromagnetische Abschirmung, und

- Fig. 8

eine Variante gemäss Fig. 7.

The invention is explained in more detail with reference to exemplary embodiments shown in the drawing, which are also the subject of dependent claims. They show schematically:

- Fig. 1

an EMC mold which represents the prior art and is inserted in a casting machine,

- Fig. 2

a partial view of a perforated plate for a mold housing,

- Fig. 3

a section through a mold in the longitudinal direction of the strand,

- Fig. 4

a variant of Fig. 3,

- Fig. 5

the active part of an electromagnetic shield,

- Fig. 6

5 shows a partial section through one leg of an electromagnetic shield corresponding to FIG. 5,

- Fig. 7

an insert for electromagnetic shielding, and

- Fig. 8

a variant according to FIG. 7.

Fig. 1 shows a known basic principle of a casting machine for vertical magnetic field continuous casting. A casting machine may comprise one or more molds 10.

An inductor 12 for a medium frequency power system creates a magnetic field and thereby that force in the strand 14 which prevents the cast Metal touches the mold inner wall 16.

A wedge-shaped electromagnetic shield 18 shields partially off the inductor 12, thereby reducing the magnetic field in the upward direction. Finally, the shield determines 18 the zone in which the cooling water 20 in the form a cooling water curtain 22 sprayed onto the strand 14.

A start-up floor 24 is on a not visible casting table assembled. The approach floor 24 forms during the starting phase the foot 26 of the cast strand 14 and supports it during the whole casting phase.

This basic principle of continuous magnetic field casting according to 1 is according to the invention with respect to the guide surface 28 for the cooling water 20, the active area 30 of the electromagnetic Shield 18 and the molded, solidly formed Chill mold housing 32 improved, but otherwise in retained essentially unchanged.

2 is an approximately 3 mm thick stainless steel sheet 34 (INOX) for producing a mold housing 32 shown. The Steel sheet 34 already includes a holes 36 of about 10 mm in diameter of about 3 mm, which later the outlet of the cooling water to serve.

The mold 10 of a casting machine shown in FIG. 3 comprises a mold housing 32 a stainless steel sheet 34. The interior formed is filled with cooling water 20 and with a water distribution block 38 provided from plastic. An electromagnetic shield 18 made of stainless steel has two inner grooves 42 for Inserting front edges of the mold housing 32. The mold housing 32 and the water distributor block 38 are made of plastic by a bolt 44 penetrated, on which a screw 46 in the electromagnetic Shield 40 attacks and the water distribution block 38 and thus the mold housing 32 tightens.

The water distribution block 38 has a proportionate deep groove 50 from which at regular intervals a (Fig. 2) cooling water channels 52 are formed, which in a Open hole 36 in sheet steel 34. The direction of the exiting Cooling water 20 is determined by the direction of the cooling water channels 52 determined.

By loosening the screws 46, the electromagnetic Shield 18 and after removing the bolt 44 also the Water distributor block 38 are removed or replaced.

Via a screwed-on bracket 54 and a bevel 56 are two interlocking, molded plastic blocks 58, 60 connected to the mold housing 22.

The inductor 12, in the present case made of copper, is with the plastic block 58 with the interposition of a temperature-resistant Insulation layer 62 screwed, which in the present Case is made of copper.

In a recess of the plastic block 60 is the adjustment and Mechanism of movement of a plastic baffle 66 arranged for the cooling water 20. An inflatable Bellows 68 moves a sealing washer 70 depending on the pressure with a corresponding hole in the plastic block 60 and the bevel 56 penetrating push rod 72. On this Push rod 72, the baffle 66 is articulated. With one also attached to the push rod 72 Spring 74 deflects the baffle 66 against the U-shape Shield plate 76 of the electromagnetic shield 18 pivoted. The electromagnetic shielding device 18 is at least in the area of the U-shaped shielding plate 76 internally cooled with water 78 because the cooling water 20 for the Strand 14 is not in external contact with the electromagnetic Shielding 18, in particular shielding plate 76, occurs.

With a pressure of, for example, 0.5 bar from the cooling water channels Leaving 52, the cooling water 20 hits in one acute angle on the guide surface 80 of the baffle 66, flows along this guiding surface, forming a water film, forms a homogeneous when detached from the baffle Cooling water curtain 22, which in turn is to be cooled Line 14 acted upon.

3, the baffle 66 is in two extreme positions drawn. The water curtain can h from 5 to 20 mm, in particular 5 to 10 mm, in each adjustable Position on strand 14 occur. So that's it Mold 10 even with rigid electromagnetic shielding very flexible. However, the water curtain can also be continuous be raised and lowered, for example in shape a sinusoidal movement.

4 instead of the baffle plate 66 one also pivotally connected to the push rod 72 Support plate 82 arranged. This support plate 82 from Plastic is used to distribute low-pressure outflows Cooling water 20, for example with less than 0.05 bar. The cooling water reaches the baffle 80 66 not. So that as a film on the guide surface 84th the cooling plate 20 flowing off the support plate 82 the strand 14 reached, the support plate 82 is longer than the baffle 66 trained and extends into the nearer area of Strands 14

Holes 86 or slots are formed in the support plate 82, so that part of the cooling water can be drained off, without reaching strand 14.

An insert plate 88 made of copper is clamped in the shielding plate 76, which has a high degree of absorption for that from the inductor Has 12 generated magnetic field. Are in the upper area two copper sheets by soldering, riveting or gluing together connected, making it more shielded in this area becomes.

On the water distribution block 38 is a flange 90 with a Fixed inlet opening 92 for the cooling water 20, for example with screws. This creates a large chamber 93 and one identical to the groove 50 in the water distributor block 38 small chamber for the cooling water 20 is formed. With the Flange 90 allows the cooling water 20 to flow more smoothly into the cooling water channels 52 will be introduced.

Figure 5 shows a detail regarding the active zone of the shield 18, which is bent by the U-shaped, on the shielding body attached shielding plate 76 is formed. There are 0.3 mm on the two legs of the shielding plate 76 thick coatings 94 of copper applied, which differ are long. This creates a graded effective electromagnetic shielding, which - as in conventional embodiments - is stronger than above below.

A variant is shown in Fig. 6. On part of the Shielding plate 76 is a thicker one from bottom to top Coating 94 applied, which one from below shielding effect continuously increasing above.

In Fig. 7 is an insert sheet bent up to the longitudinal center 88 for a U- or V-shaped shield plate 76 (Fig. 3, 4). The effect on electromagnetic Shielding is equivalent to Fig. 5.

In Fig. 8 are two superimposed, bent insert sheets 88, which is a finer compared to FIG. 7 Gradation result.

Claims (13)

1. Casting machine comprising at least one water-cooled mould (10) for the continuous casting of a vertical bar (14) in the magnetic field of an inductor (12) partially screened off from above by an electromagnetic screen (18, 76), cooling-water conduits (52) directed on to the bar (14) at an acute angle via at least one guide surface (28, 80, 84) in order to form a water film and one withdrawable starting base (24) per mould (10), characterised in that the guide surface/s (80, 84) consisting of an electrically insulating material can be displaced and/or pivoted in order to vary the height (h) at which the cooling water (20) strikes the bar (14) and the electromagnetic screen (18, 76) is internally cooled
2. Casting machine according to claim 1, characterised in that the mould housing (32) consists of a perforated sheet of stainless steel with welded side walls.
3. Casting machine according to claim 2, characterised in that end edges of the mould housing (32) are inserted into corresponding internal grooves (42) in the screen (18) and the mould housing is screwed on to the screen, preferably by means of an inserted moulded water-distributing block (38), the cooling-water conduits (52) for the cooling water (20) being formed in the water-distributing block (38) preferably consisting of plastic.
4. Casting machine according to one of claims 1 to 3, characterised in that the guide surface (80) is the surface of a displaceable and/or pivotable deflecting plate (66).
5. Casting machine according to claim 4, characterised in that the exchangeable deflecting plate (66) consists of plastic and its guide surface (80) has grooves preferably guiding the cooling water in the direction of the cooling-water conduits (52).
6. Casting machine according to claim 4 or claim 5, characterised in that a supporting plate (82) which is also displaceable and/or pivotable and comprises the guide surface (84) is provided instead of or below the deflecting plate (66).
7. Casting machine according to claim 6, characterised in that the supporting plate (82) has holes (86) or slots for draining off cooling water (20).
8. Casting machine according to one of claims 1 to 7, characterised in that the electromagnetic screen (18) is a screening sheet (76) bent into a U-shape or a V-shape in the active region of the inductor, traversed by water (78) and preferably made of stainless steel 1 to 2 mm thick, an insert (88) or coating (94) in the U-shaped or V-shaped part increasingly weakening the magnetic action of the inductor (12) in the upwardly extending direction.
9. Casting machine according to claim 8, characterised in that an inserted sheet (88) becoming thicker stepwise or continuously from the bottom to the top or a layer (94) becoming thicker from the bottom to the top is arranged on the screening sheet (76).
10. Casting machine according to claim 8 or claim 9, characterised in that the insert (88) or coating (94) consists of silver, preferably 0.05 to 0.2 mm thick, copper, preferably 02 to 0.4 mm thick, or brass, preferably 0.5 - 2 mm thick.
11. Method of cooling a bar (14) in a casting machine according to one of claims 1 to 10, in which the cooling water (20) is sprayed on to a guide surface (80, 84) at an acute angle, a uniform water film is formed and is sprayed on to the bar (14) as a water curtain (22), characterised in that the guide surface (80, 84) to which water is applied is displaced and/or pivoted to and fro continuously at a predetermined rhythm, the water curtain (22) thereby being moved up and down on the bar (14) over a height (h).
12. Method according to claim 11, characterised in that the guide surface (80, 84) to which water is applied is moved sinusoidally, preferably at an interval of 1 to 3 sec per half-wave, moving the water curtain (22) up and don on the bar (14) over a height (h) of 5 to 20 mm, preferably 5 to 10 mm.
13. Method according to claim 11 or claim 12, characterised in that the guide surface (80, 84) is preferably moved in a program-controlled manner by a pneumatic, hydraulic or electromagnetic drive.

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