KR100515460B1 - Continuous casting ingot mould for the vertical casting of metals - Google Patents

Abstract

The ingot mold of the present invention comprises a tubular metal member 4 of copper or a copper alloy, which circulates water to the outer wall of the tubular metal member and cools to cause peripheral solidification of the cast metal as it contacts the inner wall of the metal member. Include. The mold also includes an uncooled heat insulating refractory material feeder bush 9 for extending to the top of the cooled metal member to contain the liquid cast metal and defining therein a continuous calibrated channel for the cast metal. A metal ring 16 is cooled between the tubular member 4 and the feeder bush 9 and is aligned with the inner wall of the tubular member where the interior is cooled and the fluid circulates horizontally. The present invention avoids deformation of the upper end of the cooled metal region of the ingot mold.

Description

Continuous casting ingot mold for vertical casting of metals {CONTINUOUS CASTING INGOT MOULD FOR THE VERTICAL CASTING OF METALS}

The present invention relates to continuous casting of metals, in particular steel. This particularly relates to the technique of "vertical hot melt continuous casting".

The first article of this technology has already been published at the end of the sixties, a good example is FR-A-2,000,365. Thereafter, an adiabatic feed head intended to include molten metal conveyed in a liquid state by a tundish positioned above the feed head is initiated and done by a predetermined solidification of the " active " The fact that it is installed on top of a actively cooled tubular metal component distinguishes it from conventional vertical continuous casting, which is now widely practiced worldwide.

This "active" component is conventionally a tube made of a single piece (for casting billets or blooms) or made of plates (for casting slabs or large blooms) joined together. It is made of copper, or a copper alloy, and in order to make it possible to induce sufficient heat flux, it is actively cooled by intense circulation of water with respect to the outer wall of the component so that molten metal solidifies in contact with the inner wall of the component. To ensure that.

These two successive components comprise a still-liquid core and are in the form of a solid shell resulting from peripheral solidification of the cast metal, which enters the molten state via the top and contacts the cooling wall of the template. Define a continuous sizing passage for the cast metal that escapes via the bottom of the furnace. Thereafter, solidification is continued so as to terminate at the bottom of the casting machine by the injection device.

The basic advantage obtained in vertical hot melt continuous casting is that the casting metal, which is injected into the mold and placed in the refractory feed head ("meniscus"), is inevitably contacted by the casting metal for the first time with the cooling wall of the mold. The point of initiation of solidification, that is, a certain distance from the top edge region of the copper component.

Thus, the solidification process starts in a hydrodynamically quiet environment and is much more than in conventional continuous casting, since turbulence, particularly caused by the inflow of molten metal, remains confined within the buffer volume provided by the refractory feed head. It is intended to continuously cast semi-finished products of good metallurgical properties at high extraction rates.

In addition, this technique does not have any significant drawbacks as compared to conventional continuous casting and can be seen to have evolved from conventional continuous casting and thus is not associated with any major technical step. In particular, because the tundish is located a short distance above the casting machine but is not firmly connected to the mold, it converts a conventional continuous casting machine into a hot-top continuous casting machine without particular difficulty. It is possible to do However, although the first publication of continuous castings of steel was concurrent with the introduction of many known advances (more than 80% of the world's steel production is now produced by continuous casting), the introduction of vertical continuous casting into the industrial sector. In the process of applying the hot casting continuous casting technology to the industrial field, it is still in the research stage.

Experiments conducted by the applicants revealed a major problem that could explain the lack of water solubility from an industrial point of view, ie, morphological instability over time at the "cooled copper component / refractory feed head" interface. . This is because this shape is affected by the deformation of the upper end of the cooled component.

In conventional vertical continuous casting, such deformation is caused by an unexpected increase in the liquid metal, which may be high enough to overflow from the mold. This has little effect on the continuation of the casting process. In contrast, in continuous continuous casting, the situation is permanently similar to that of the "spill-over" type, since the meniscus is moved upstream of the cooled component. Thereafter, deformation at the upper end of the copper component, precisely at the point where a predetermined solidification of the cast metal is initiated, becomes unsuitable (penetration of molten metal under the feed head, poor coordination with the feed head, etc.). .

1 is a schematic vertical cross-sectional view of the top of a machine for vertical hot dip continuous casting of steel according to a known prior art general design;

2 is a partially enlarged view of a top part of a machine of the type described above, except that the design according to the invention is shown in detail.

In the drawings, like elements are referred to by like reference numerals.

It is an object of the present invention to in particular avoid any thermomechanical deformation of the upper end of the cooled component during casting.

In order to achieve the above object, the present invention provides a cooled tubular metal component 4 and a cooled metal construction intended to ensure solidification of the cast metal 10 in the vicinity of the contact with the inner wall of the metal component. An uncooled feed head 9 which is located on top of the element and is intended to hold a liquid cast metal and defines a continuous sizing passage for the cast metal with the component and is made of insulating refractory, and also with the metal component In a continuous casting mold for vertical hot melt continuous casting of metal, which includes a metal annular portion 16 added between the feed heads and cooled by annular internal circulation of a coolant, the passage of the passage provided to the cast metal 10 by the mold. In order to satisfy the continuous properties, the annular portion 16 has a solid inner wall 26 which is continuously aligned with the tubular metal component 4. And a gong.

Preferably, the annular portion is made of the same metal as the cooled tubular component, ie made of copper or a copper alloy.

Also preferably, this annular portion is mounted to be removable and can be easily replaced.

According to various advantages of the invention, the annular portion comprises an internal cooling circulation consisting of an annular circulation chamber of coolant, which chamber is formed along the annular inner wall around the periphery of the mold, preferably very close to this wall. .

As is already clearly understood, an essential feature of the present invention is the insertion of a cooling body (an annulus) between the mold tube and the refractory feed head which contributes to the expansion of the main tubular component, the cooling body being the same. Although made of material and having a magnetic cooling circuit, the relatively small height (relative to the height of the tube) of the cooling body is provided by the cooling system for the tube at the end region of the cooling body, in particular at the upper end facing the feed head. A cooling effect much larger than the height can be obtained. More specifically, the tubes of continuous casting molds are usually 0.7 to 1.0 m in length, while the annular part according to the invention has a height of, for example, 4 to 10 cm.

In terms of the casting process, this moves the solidification start plane up to the upper end of the annular portion. In other words, in order to fulfill the solidification initiation function, the cooled tubular component of the mold preferably replaces the removable and cooled autonomous annulus, but because of the small height compared to the height of the main tubular component of the mold, The cooling effect at that end is of course more effective, making it possible to incorporate therein a sheet of cooling water which circulates horizontally rather than vertically.

In this regard, in fact, in order to extract the significant total heat flux imposed by the progress of the peripheral solidification of the cast metal traveling the entire length, firstly the cooling circuits involved in the need to ensure that the overall working height is excessively cooled (end) The technical limitation of the water jacket connecting the two chambers in this case reaches its limit in preventing deformation of the end of the tube if the temperature at this point rises to the temperature of the molten steel.

The present invention overcomes the above obstacles by means of an additional body that is too high and overcooled to incorporate the horizontal circulation of the coolant therein, thereby contacting the refractory feed head to avoid deformation in contact with the molten metal. To effectively cool both of the upper ends of the tubes of the mold in intimate contact via the upper edge and the lower surface.

In view of the following description given by the method of the embodiment with reference to the attached single plate drawing, the invention will be clearly understood and other aspects and advantages will become more clearly apparent.

Referring to the general view of FIG. 1, the upper part of a machine for vertical hot dip continuous casting of steel is an outlet orifice (or a few) extending by an induction nozzle 20 in the extraction direction of the metal to be manufactured, ie from the top to the bottom of the figure. It can be seen that the molten metal is transported to the underlying mold 3 by means of two outlet orifices and provided with a tundish 1 comprising a bath of molten metal 2.

As shown, the mold comprises a tubular copper component 4 which is actively cooled by the circulation of water over the entire length of the outer surface. Conventionally, a steel liner 5 has been provided around the vicinity of the tube 4 for this purpose in order to channel the vertical sheet 21 of circulating water. The liner 5 has openings 22 at its ends that allow the sheet 21 of water to communicate with the inlet chamber 6 and the discharge chamber 7, which chambers at a distance from the opening 5. The limit is determined by the casing 8 which surrounds.

On top of the inner tubular component 4 is a feed head 9 made of uncooled refractory, the inner wall of which is aligned with the inner wall of the body 4, and in some cases not rearwards. It is preferable not to.

In the context of the casting process, the arrangement of "cooled metal component 4 lying on insulated refractory feed head 9" defines a sizing passage for the cast metal, wherein the top 12 of the passage in the feed head is a mold bundle. And constitutes a buffer zone which limits the hydrodynamic disturbances caused by the arrival of the flow part 11 of molten metal, the lower part 13 of the passage extending the feed head being the solidification zone of the cast metal.

As shown, this solidification begins immediately after the first contact of the cast steel with the inner wall of the cooled copper component 4, ie along the upper edge 14 of the wall, the thickness of which grows from the periphery to the center. It forms a solid shell 15 and continues downwards. Upon leaving the mold, the shell 15, having a thickness slightly greater than 1 cm, is strong enough to withstand the ferrostatic pressure of the stationary liquid core 24 and is located at the bottom half of the machine, not shown. Under the influence of the water spray unit, its centripetal growth is continued until the semifinished product 10 is completely solidified. Once the semifinished product has solidified completely, it is cut into portions of a predetermined length (billets, blueum or slabs, depending on the shape of the casting section) and these portions are then available for a series of forming processes (rolling, etc.).

With particular reference to FIG. 2, in accordance with the invention, the annular portion 16 is located on top of the tubular component 4, extending the tubular component, made of a copper alloy, and having a magnetic cooling system. By cooling. In the example described, the annular portion consists of a chamber 17 formed along the solid inner wall 18 of the annular portion at a short distance from the solid inner wall. The chamber is circular in shape and has an inlet and an outlet close to each other on either side of the partition wall closing the chamber. Therefore, a cooling circulation in the form of a horizontal annular portion occurs, and a horizontal circulation of a coolant (for example, water) surrounding the annular portion and the cast product is established.

In FIG. 2, only the coolant inlet nozzle 19 and the outlet nozzle 19 ′ connecting the circulation chamber 17 to the outside are shown.

The cooled annular portion 16 is directed towards the bottom to fit well with the top surface of the component 4 on which it is placed and to prevent any penetration risk of molten metal.

The cooled metal assembly formed by the annular portion 16 and the tubular component 4 constitutes the actual “active” portion of the mold. In terms of cast metal, these two components in parallel without any breakage between them are unitary because the solidification of the cast metal begins and continues to grow as the cast product 15 proceeds downwards inside this assembly. It acts as an element. The starting plane of this solidification is no longer a plane passing through the upper edge 14 of the component 4 but a plane passing through the upper edge 23 of the annular portion 16.

On top of this assembly 16, 4, as already shown, an adiabatic feed head 9 is laid.

According to a preferred embodiment of the invention, this feed head 9 itself is also formed of two nested individual components as follows.

-Upper bush 25 made of refractory with insulating properties, since it is necessary to prevent any early spurious solidification of the cast metal in the turbulent region 12. The selected material may be a fibrous refractory such as a material sold under the trade name A 120K of the French company KAPYROK. And

In the vicinity of the crystallizer 4-16, the mechanical by the upper tip of the solid shell 15 on the edge 23, while the entire assembly undergoes the normal vertical oscillation motion necessary for the success of the casting process. It is added by the inherently continuous nature of the corrosion and casting process and because the thermomechanical stress of the machine operating in the thermal cycle should be prevented as far as possible, the lower component made of refractory material adopted for good mechanical strength (ring (26)). Preferably a material such as SiAlON (Sialon) doped with boron nitride will be perfectly suitable.

Preferably, a circuit for injecting waste inert gas (for example argon) is provided between the feed head 9 and the metal assemblies 16, 4.

This circuit is made at the feed head 9 / metal assembly 16, 4 interface, appears at one end around the inner periphery of the mold, is itself connected to a source of pressurized argon, not shown and calibrated. Its other end is connected to a plenum chamber 29 which is supplied with argon via the supplied nozzle 30.

The benefit of the feed head made as two nested parts is that it can improve the mechanical strength of the underlying parts susceptible to corrosion caused by the "back and forth" motion of the solidified tip adjacent to the cast metal, By vertical vibration.

Therefore, this strong lower ring 26 has less thermal insulation properties than the upper part. The cast metal may form an early coagulated film at the point of contact between the aligned inner wall 27 and the inner wall of the cooled annular portion 16. This film is the main source of heterogeneity with respect to the controlled solidification process in the cooled metal assemblies 16, 4. This is an advantageous embodiment of the present invention and the objective for breaking the coagulated film formed on the ring 26 as known from FR-A-93 03871 and the uniform and rapid method in contact with the cooled annular portion 16. This is why the curtain of argon is blown in the base of the feed head 9 for the purpose of solidifying the cast metal in a rapid manner.

The basic advantage of the present invention is that since the upper part of the most stressed mold is made in the form of an additional part (annular part, 16), the inner tubular part under economic conditions compatible with the industrial implementation of the hot melt continuous casting If component 4 of is not to be replaced, it can be easily replaced with new parts as needed.

According to another advantageous embodiment, the tendency of the shell 15 to adhere to the walls of the mold is characterized by injecting a lubricant through the copper component 4 (see FR-A-91 01551) and cooling the component ( By vibrating this component using an ultrasonic transducer provided at the free end of the upper return 32 of 4), it is reduced by adding a known lubricant. Such a transducer may be of "piezoelectric" type.

There is no need to incline the application direction of the ultrasonic waves (see, for example, FIG. 2). Nevertheless, the inclination has the advantage of combining the vertical vibration effect with the horizontal vibration effect, both of which contribute to reducing the friction between the castings 10 in the mold.

More specifically, reference may be made to FR-A-89 07839.

It is needless to say that the invention is not limited to the described embodiments, but extends to equivalents and variations therefrom as long as the essential features given in the claims are related.

In particular, the invention applies to long products as well as flat products. Thus, the words used such as "annular part", "annular part" or "ring", etc., although they imply a circular shape, are made of a template consisting of a plate assembled with cooled inner tubular components (eg For example, as a mold including a slab or a large bloom continuous casting mold, it should be understood in a more general sense.

Likewise, the present invention applies to the continuous casting of steel as well as other continuously castable metals, in particular metals having a lower melting point than steel, such as aluminum or copper.

Claims (7)

A cooled tubular metal component 4 intended to ensure solidification of the cast metal 10 in the vicinity of the contact with the inner wall of the metal component; An uncooled feed head 9 which is located on top of the cooled metal component and which is intended to retain the liquid cast metal and which, together with the component, defines a continuous sizing passage for the cast metal and is made of adiabatic refractory; Also in a continuous casting mold for vertical hot melt continuous casting of metal, which is added between the metal component and the feed head and comprises a metal annular portion 16 cooled by annular internal circulation of a coolant, In order to satisfy the continuous properties of the passages provided to the cast metal 10 by the mold, the annular portion 16 has a solid inner wall 26 which is continuously aligned with the tubular metal component 4, The cooled metal annular portion 16 comprises an internal cooling circuit consisting of a chamber 17 for horizontal circulation of coolant, wherein the chamber is formed along the inner wall 18 of the annular portion around the mold. . The mold according to claim 1, wherein the cooled metal annular portion (16) is made of the same metal as the tubular metal component (4). The mold according to claim 1, wherein the cooled metal annular portion (16) has a height of 4 to 10 cm. Mold according to claim 1, characterized in that the annular portion (16) is removably mounted to the tubular metal component (4). The refractory feed head (9) according to claim 1, wherein the refractory feed head (9) has two nested individual components: an upper bush (25) made of a refractory having good thermal insulation properties and a lower ring (26) made of a refractory having good mechanical strength. A mold comprising: 6. A circuit as claimed in claim 1 or 5, characterized in that it comprises a circuit (28, 29, 30) for injecting inert gas around the inner periphery of the mold between the feed head 9 and the annular portion 16. template. The mold as claimed in claim 1, wherein the mold comprises an upper revolving portion (32), and an ultrasonic transducer (31) for vibrating the mold at the end of the upper revolving portion (32).