DE2457422C3 - Device for continuous casting from layers of metallic melt - Google Patents

Description

The invention relates to a device for continuous casting from layers of metallic melt, with a Melt container, a cooled continuous casting mold and one at an angle to the direction of the strand Cooling surface that can be moved back and forth in the direction of strand travel to control the flow of melt.

At a well-known institution (Herrmann »Hand · ' book of continuous casting ", p. 149 Fig. 495) to the horizon * Tal continuous casting is a pouring funnel with a mouthpiece that can be moved horizontally back and forth Continuous casting mold ähgeschlösseh and ah a boom the mold a Klemmsegrflent to take initially of the starting bolt and later of the solidifying cast strand stored, while a second clamping segment for holding the starting bolt or the string in the opposite direction is fixedly mounted at the common movement of the mold and the starting bolt or strand away from the mouthpiece Space for a certain amount of molten metal to flow in when the starting bolt is at a standstill or strand and movement of the mold towards the mouthpiece begins to solidify and the next

ίο joint movement of mold and starting bolt or strand is taken away from the mouthpiece.

Here, as with the usual vertical continuous casting molds, the heat is extracted from the melt only discharged to the outer surface, the melt only reaching the mold wall in a narrow edge zone directly touched The heat to be dissipated from the core of the forming strand therefore has a long duration Way with a low temperature gradient and above all to overcome the heat-insulating gap that is A metal sump protruding far into the strand forms between the shrinking strand and the mold, which solidifies only slowly compared to the edge zone and thus one over the strand cross-section The consequences are uneven structure.

In another known device of the type mentioned (DE-OS 15 08 854) is on Bottom of the Schmebenbehälters a conical continuous casting mold is provided, the walls of which as Cooling surfaces are formed. This mold performs back and forth movements in the direction of strand travel, wherein the strand is moved through the melt in one direction of movement, while in the in the other direction of movement, melt flows into the gap between the mold and the strand, which then solidifies The disadvantage here is that the heat is not dissipated solely via the conical cooling surfaces of the mold is sufficient, especially since the solidified conical layer just formed at the strand end by the melt is performed, which leads to deviations or even liquefaction of the strand material

The object is to design the aforementioned device so that to achieve a uniform Strand structure the strand is intensively cooled when the layers solidify.

This object is achieved in the device mentioned at the beginning in that the cooling surface (12) is arranged on a punch (9) which is movable relative to the continuous casting mold (1) such that the Cooling surface (12) with iwrer movement in the strand running direction in the mold cavity of the continuous casting mold (1) whose inflow side engages. Advantageous refinements can be found in the subclaims.

With the device it is achieved that the forming strand passes through the cooling surface once at the end is cooled on the other hand at its periphery by the continuous casting mold on the punch.

The melt forming the strand is therefore not only made up on its circumference, but also through the punch Heat is withdrawn from its interior, causing rapid solidification of the melt and thus considerable Increased performance of the device is achieved. In doing so, the quality of the strand produced becomes essential improved because of this type of cooling The melt temperature can be kept at least approximately the same over the entire cross-section, What to their desired uniform solidification and thus to a uniform and dense structure while avoiding the disadvantageous formation of cavities or Von

Segregation (segregation) leads

Is the cooling surface acting on the cross-sectional area of the strand end during the cooling phase tracked according to the shrinkage of the metal, a constant heat transfer between the Reached strand and the cooling surface. Appropriately, a pressure is applied to the by the stamp solidifying melt exerted

Is the cooling surface on the punch at an angle to the strand running direction, for example with a conical or hyperbolic formation of the cooling surface, then the cooling surface in the direction of the stranjjjjjj the cast in, cooling Melt-acting pressure in a component following the slope and a component acting perpendicular to it divided The size of the pressure can be controlled so that especially with alloys with different solidification of individual components a shift of z. B. already frozen or in the Solidifying constituents compared to the constituents still in the liquid phase This can cause any tendency to segregate while cooling down very quickly at the same time, it has enough effect and a strand structure of optimally uniform composition is achieved with maximum performance will. In the case of alloys with at least one solidification interval between the components, can be achieved by applying appropriate pressure that the first solidified emptying component is plastically deformed.

Embodiments of the invention are explained in more detail below with reference to the drawings

F i g. 1 shows a first exemplary embodiment with a die, the cooling surface of which is at right angles to the direction in which the strand is running is arranged;

F i g. 2 shows a further embodiment with a stamp, the cooling surface of which is conical;

F i g. 3 a third embodiment in which the inflow end of the continuous casting mold is frustoconical is trained;

F i g. 4 shows a fourth embodiment in which the melt container and the punch form a structural unit form;

5 shows an exemplary embodiment corresponding to FIG. 1 in a first working position and

F i g. 6 in a second working position.

In FIG. 1, the continuous casting mold 1, the mold cavity of which is cooled at the periphery, has a central opening 3. Above this is a pouring funnel 4 as a melt container. Below the continuous casting mold 1, a discontinuously operating extraction device, not shown here, is arranged. In the center of the pouring funnel 4, a punch 9 is guided through a bracket 5, the end wall of which is cooled with water as a cooling surface 12, while its peripheral surface carries a jacket 6 made of fireclay with an underlying heat-insulating plastic fleece 6a. Its cross section corresponds to that of the mold cavity of the continuous casting mold ϊ. When lifting of the punch 9, the opening 3 is released to the continuous casting mold 1 at the transition of the sprue ·· 4 and when Abse "the continuous casting mold ken locked. At the output 1 \ H a caliber ring 10 fixed" brought

When the ram 9 is raised, the melt flows from the pouring funnel 4 through the opening 3 into the Continuous casting mold 1 according to, t'Hd to the extent that the punch 9 barely releases in the continuous casting mold. Thereupon the punch 9 is on the flown Melt layer lowered, whereby opening 3 is blocked. The layer of melt is attached to hers Front face and cooled on its periphery and advantageously compressed during solidification the compaction pressure, which only covers the respective layer, is dimensioned so large that the structure of the alloy components that solidify first is compressed. As a counter-holder the already solidified strand or the caliber ring 10, which at the same time forms the circumferential surfaces, is used for the pressure

ι ο of the strand 7, which when lowering the punch 9 through it is pushed through, smooths and the edge zones of the strand compacted

Fig. 2 shows another embodiment of such a continuous casting device. Also here is up again the water-cooled continuous casting mold 1 of the pouring funnel 4 serving as a melt container is placed and the The punch 9 is guided in a bracket 5 that can be raised and lowered centrally. It is also back with a thermal insulation Coat 6 provided. However, its outer diameter, including the jacket 6, is slightly smaller than that Inner diameter of the mold cavity »of the continuous casting mold 1. The essential thing here is that the as The die end wall serving for the cooling surface 12 is not flat, but rather is designed to project conically, as a result of which the contact cooling surface 12 is enlarged.

They are wildly cooled from the inside by water that is fed through the pipe 8 and after the pressure flows Stamp cavity is discharged through a further line, not shown.

As a result of the contact with the large conical cooling surface 12, when the punch 9 is raised The amount of melt that has flowed in is strongly cooled from the inside and begins to solidify so quickly that when following lowering of the punch 9 only an insignificant

rather part of the melt through the opening 3 again in the sprue 4 can return. Rather, with continued cooling, the remaining solidifying The melt layer compresses and then the strand is pushed out one step further.

When the ram 9 is raised again, the melt flowing in from the pouring funnel 4 fills again the conical space between the cooling surface 12 and the solidified strand and the work cycle begins new.

According to the further example according to FIG. 3 , the punch 9 fits into the opening 3a between the pouring funnel 4 and the continuous casting mold 1. A frustoconical cooling surface 12a is provided here on the continuous casting mold 1, which is cooled together with the cylindrical mold wall la. When the ram 9a rises, the melt passes from the pouring funnel 4 into the opening 3a. During the subsequent decline of the punch 9a, it is displaced from it into the mold cavity of the Kckillt 1, where it moves the strand 7, welded to it as a new layer and solidified by cooling, especially on the cooling surface 12a. The next time the punch 9a goes up again melt into the opening 3a.

F i g. 4 gives a similar device, also for alternating casting and cooling or compression of the building strand 7 again. Here is the one The pouring funnel 14 is combined with the punch 9. The only opening 13 is arranged centrally Cooling surface 12 on the punch 9 is z. B- hyperboloid for *

mig into the mold cavity of the continuous casting mold 1. The cooling surface 12 can in principle have any desired inclination to the longitudinal axis of the strand to be formed occupy and the cross-section in whole or in part

capture. When lifting the stamp 9, you can see it Movement Hardly for a new layer of melt to flow through the pouring opening 13 Lowering the punch 9 for the cooling, solidification and compression process, the strand 7 is pushed out, the force required for this is transmitted through the already solidified layer. Through the Hyperboloid-like design of the cooling surface 12 is achieved that the thickness of the melt layer to Equalization of the cooling effect over the cross-section of the strand increases from the inside to the outside or from top to bottom. As is easy to see, is the cooling effect outer * at the transition of the cooling surface 12 to the wall of the continuous casting mold 1 is greatest, and you can by the described shape of the cooling surface 12 the Adapt the greater thickness of the melt layer to the stronger cooling effect that occurs and thus make it even more uniform achieve solidification across the strand cross-section.

The shape of the cooling surface 12 in the examples described above can be varied as required; she can, as shown, flat or hyperbolic, but also convex or concave or conical be.

The F i g. 5 and 6 show a further embodiment, wherein Fig. 5 illustrates the state in which the The punch is lowered onto the melt for cooling, while FIG. 6 shows the state in which at The melt flows into the mold with a rising punch.

The pouring funnel 4 is placed on the mold 1. In it, the stamp 9 is centrally immersed, with his Cooling surface 12 can be lowered onto the melt within the continuous casting mold 1.

The punch 9 consists of an outer punch 15 and an inner punch that is longitudinally movable to a limited extent therein 16. The inner punch 16 is connected to a pressure cylinder 17 and is through this can be raised and lowered. The limitation of the longitudinal mobility of the inner punch 16 in the outer punch 15 is due, on the one hand, to the abutment of its end face 18 against the inside of that serving as cooling surface 12 Front wall of the Auüensiempeis lä and auren Anscniag its shoulder 19 against the upper boundary surface 20 of the outer punch 15. The lateral surface 21 of the Outer punch 15 has cooling grooves 22 running in a spiral on the inside. through which the reflux of the through the The longitudinal bore 16 ′ of the inner punch 16 is fed in and the one in its end face 18 is radially shaped arranged cooling grooves 18 'is carried out by flowing cooling water

On the jacket l \ of the outer die 15 is a special insulating jacket 23 made of heat-insulating material. It is carried along by the outer punch 15 through a driver collar 24 which engages in an annular recess 25 with longitudinal play when it is lifted after a corresponding idle travel. The end face 26 of the insulating jacket is designed as a conical sealing surface and corresponds to a conical stop surface 27 at the mouth of the pouring funnel 4. The insulating jacket 23 has heating spirals 28 within its outer peripheral surface and cooling spirals 29 in its inner surface facing the punch 9.

The mode of action is as follows:

In the case of the FIG. The state shown in FIG. 5 is the stamp 9 almost reached its lowest position and the insulating jacket 23 has the pouring funnel 4 from the Continuous casting mold 1 completed. Cooling off the Melt in the Gießtrichler4 should pass through the heating coil 28 in the insulating jacket 23 can be avoided. On the other hand, the jacket 21 of the outer die 15 is both through the cooling spiral 29 in the insulating jacket 23 as well as through the cooling water flowing in its interior along the cooling grooves 22 is continuously cooled, and the outer die 15 in turn cools the cross-sectional area of the melt layer introduced into the mold with its cooling surface 12. During its further downward movement, the punch 9 compresses with the cooling surface 12 of the outer punch 15 the solidifying melt in the continuous casting mold 1 and then pushes the strand forwards.

If the inner ram 16 is then raised by the pressure cylinder 17, after a certain idle travel it takes the outer ram 15 upwards with the shoulder 19 against the upper boundary surface 20. In the free space that is formed between the end face 1R Hes Innenslemnnls lfi iinrl of the cooling surface 12 of the outer die 15, the cooling water flows in at an accelerated rate and intensively cools the two surfaces it rinsed, whereby it is of particular advantage that the cooling surface 12 of the outer die 15 is already there is lifted from the solidified but still hot melt layer. The inflowing cooling water acts directly on the wall of the cooling surface 12 of the outer die 15, which is kept particularly thin for the purpose of rapid heat dissipation, whereby it is rapidly cooled. At the same time, however, the bottom surface of the inner punch 16 is also acted upon directly by the inflowing cooling water. The inner punch 16 is thus also cooled down relatively quickly.

As the upward movement continues, the

Insulating jacket 23 taken along by the collar 24 and

is also raised. As a result, as shown in FIG. 6th shows that the entry into the continuous casting mold 1 is free and the melt flows into the free space between the upper solidified metal layer in the continuous casting mold 1 and the cooling surface 12.

The inner punch 16 is now lowered by the cylinder Y1. The passage from the pouring funnel 4 into the continuous casting mold is blocked and the end face 20 of the insulating jacket 23 meets the mating surface 27 on the pouring funnel 4 in a sealing manner.

When the inner punch 16 is lowered, the between the surfaces 18 and 12 is displaced located cooling water the cooling surface 12 of the outer die, which is already back on the new The melt that has flowed in has initially been so intepHv due to the cooling water flowing behind it cooled so that the melt does not weld onto the cooling surface 12 Inner punch 16 up to the end position, this lies over its end face 18 with its large cooled mass directly conducts heat to the cooling surface 12 and thereby additionally conducts a larger amount of heat from this and the solidifying melt.

Meanwhile, the punch 9 has pushed the strand 7 down a little out of the continuous casting mold, because by the direct contact of the end face 18 of the inner punch 16 on the thermal engineering Due to the thin wall of the cooling surface 12, this has been mechanically reinforced at the same time and could the feed pressure and / or the pressure applied to compress the solidifying melt without transferred further.

For this purpose 3 sheets of drawing a

Claims (7)

Patent claims: 1. Device for continuous casting from layers of metallic melt, with a melt container, a carbonized continuous casting mold and one at an angle to the strand running direction, in the strand running direction reciprocating cooling surface for controlling the melt inflow, characterized in that, that the cooling surface (12) is arranged on a stamp (9) which is relative to Continuous casting mold (1) can be moved in such a way that the cooling surface (12) moves in the direction of travel of the strand engages in the mold cavity of the continuous casting mold (1) on its inflow side 2. Device according to claim 1, characterized in that that centrally on the continuous casting mold (1) a pouring funnel (4) in which the punch (9) is central is guided, is placed in such a way that the stamp (9) during its to-and-fro movement, the opening (3) of the inflow se ^ e of the continuous casting mold (1) releases and locks 3. Apparatus according to claim 1, characterized in that the punch (9) has the lower part of a Forms pouring funnel (14) 4. Apparatus according to claim 1, characterized in that the punch (9) is in two parts, such that an inner punch (16) is limited longitudinally movable in an outer punch (IS) with a thin end wall forming the cooling surface (12), so that it located in its movement against the direction of Gußstrangbewegung with its end face (18) of the inside of the end wall of the outer plunger (15) eiiifernt ..nd reversed in its movement in the direction of strand movement by its end face (18) at d t opposite side of the end wall of the Outer punch (15) comes to the plant. 5. Apparatus according to claim 1 or 4, characterized in that in addition to the end wall of the Stempeis (9) nor whose jacket surface (21) is water-cooled from the inside, with means for Movement of the cooling water along the surfaces to be cooled are provided. 6. Apparatus according to claim 4, characterized in that the inner punch (16) for reciprocating Movement is driven and takes the outer ram (15) with it. 7. Apparatus according to claim 5, characterized in that the inside of the lateral surface (21) of the outer die (15) is provided with helical cooling grooves (22).