Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
  • B22D11/0401—Moulds provided with a feed head

Definitions

• the present invention relates to the continuous casting of metals, in particular steel. It relates more specifically to the technique known as "Continuous Casting in Vertical Load”.
• the primary advantage sought by Continuous Casting in Vertical Load lies in the fact that it thus succeeds in distancing the free surface of the metal cast in an ingot mold (the "meniscus"), which is then located within the refractory riser, from the place where the solidification of the cast metal necessarily arises from the first contact with the cold wall of the mold body, that is to say at the edge of the upper end of the copper element.
• the aim is thus to continuously pour semi-finished products of better metallurgical quality and with high extraction speeds, or even higher than in Classic Continuous Casting, because the solidification process then begins in a calm environment in terms of hydrodynamics, all turbulence, in particular that caused by the arrival of molten metal, remaining confined in the buffer volume offered by the refractory riser.
• the object of the invention is precisely to avoid thermo-mechanical deformations of the upper end of the copper-cooled element during casting.
• the invention relates to an ingot mold for casting
• Continuous vertical loading of metals, steel in particular, comprising a tubular metallic element (made of copper or copper alloy) cooled, in particular by circulation of water against its outer wall, and intended to ensure the peripheral solidification of the metal cast in contact with its internal wall, and an uncooled extension in heat-insulating refractory material surmounting the cooled metal element, intended to contain molten metal, and defining with it a continuous calibrating passage for cast metal, ingot mold characterized in that a metal ring, cooled by annular circulation of cooling fluid, is added between the tubular metal element and the heat-insulating extension, and the inner wall of which is full and aligned with said metallic tubular element without discontinuity between them so as to respect the continuous nature of the passage offered by the mold to the cast metal.
• this ring is made of the same metal as the cooled tubular element, that is to say of copper or copper alloy.
• this ring is removably mounted so that it can be easily replaced.
• the ring comprises an internal cooling circuit constituted by an annular circulation chamber of a cooling fluid which runs along the internal wall of the ring around the periphery of the mold, and preferably at immediate vicinity of this wall.
• the invention therefore consists in its essential characteristics to be inserted between the ingot mold tube and the refractory riser, a cold body, the ring, which in fact constitutes an extension of the tubular element main of which it is made of the same material, but having its own cooling circuit, and whose relatively low height (compared to that of the tube) allows a cooling efficiency much higher than what the cooling system could do at best of the tube, at its ends, in particular the edge of its upper end turned opposite the extension.
• the tube of an ingot mold for continuous casting is usually 0.7 to 1.0 meter long, while the ring according to the invention is, for example, 4 to 10 centimeters high.
• the cooled tubular element of the ingot mold is replaced by an autonomous ring, preferably removable, also cooled, but the cooling effect of which at its ends is naturally more effective in because of its low height, compared to that of the main tubular element of the ingot mold and therefore of the possibility of installing therein a blade of cooling water circulating horizontally and no longer vertically.
• the invention overcomes this obstacle by means of an attached body, also intensely cooled, but of low height so as to be able to install there a horizontal circulation of the cooling fluid and thus ensure both efficient cooling of its own edge greater than the contact of the refractory riser to prevent its deformation at this point in contact with the molten metal, and the upper end of the mold tube with which it is in close contact through its underside.
• FIG. 1 shows schematically, in vertical section, the upper part of a continuous casting machine with vertical steel load according to the usual design of the known prior art
• FIG. 2 is an enlarged partial view of the upper part of a machine of the aforementioned type but showing in detail the design according to the invention, according to a most complete embodiment.
• a distributor 1 (or "tundish") containing a bath of molten metal 2, which it distributes to one (or more) ingot mold 3 placed below by means of one (or more) outlet orifice extended by a guide nozzle 20.
• the mold comprises, as can be seen, a tubular copper element 4 energetically cooled by circulation of water along its outer face.
• a steel jacket 5 is provided for this purpose, around and at a short distance from the tube 4, to channel a sheet of water with vertical circulation 21.
• the jacket 5 has at its ends openings 22 which put the blade of water 21 in communication with an introduction chamber 6 and with an evacuation chamber 7, delimited by a mantle 8 surrounding the jacket 5 at a distance.
• the internal tubular element 4 is surmounted by an extension 9 made of uncooled refractory material, the inner wall of which is preferably aligned with that of the body 4 (and in any case, not recessed).
• the assembly "cooled metal element 4 surmounted by the insulating refractory riser 9"
• This solidification is initiated from the first contact of the cast steel with the inner wall of the cooled copper body 4, namely on the upper edge 14 thereof, and continues towards the downstream, forming a solid crust 15 whose thickness increases from the periphery towards the center.
• the crust 15, a little more than a centimeter thick is strong enough to withstand the ferrostatic pressure of the still liquid core 24 and continues its centripetal growth until complete solidification of the semi-finished product sunk 10 under the effect of the water spraying ramps, not shown, located in the lower half of the machine.
• the semi-finished product is cut into sections of desired length (billets, "blooms" or slabs, depending on the format of the casting section) and these sections are then available for further processing (rolling, etc.).
• the tubular element 4 is surmounted by a ring 16, which extends it, also made of copper alloy and also cooled, but by means of its own cooling system.
• the latter in the example described, consists of a chamber 17 running along the solid inner wall 18 of the ring at a short distance.
• This room here circular in shape, has its input / output adjacent to each other on either side of a partition which closes off the room.
• a cooling circuit is thus produced in the form of a horizontal ring and in which an annular, therefore horizontal circulation of cooling fluid (water for example) is established, surrounding the cast product.
• cooling fluid water for example
• the cooled ring 1 6 is surface at its base so as to closely match the upper surface of the element 4 on which it rests, and thus avoid any risk of infiltration of molten metal.
• the cooled metal assembly formed by the ring 16 and the tubular element 4 constitutes the "active" part proper of the mold.
• these two elements juxtaposed without discontinuity between them become one, because this is where the solidification of the cast metal begins and its growth as the cast product 1 5 progresses downward inside this set.
• the starting plane for this solidification is no longer the plane passing through the upper edge 14 of the element 4, but that passing through the upper edge 23 of the ring 16.
• thermo-insulating extension 9 This assembly 1 6-4 is surmounted by the thermo-insulating extension 9 seen previously.
• this extension 9 is also formed by two separate superimposed elements:
• a fibrous refractory for example the material marketed under the name A 1 20K by the French firm KAPYROK.
• the ring 26 made of refractory material chosen for its good mechanical strength, because it is a matter of resisting as best as possible, in the vicinity of the crystallizer 4-16, against the mechanical erosion of the upper tip of the crust solid 1 5 on the edge 23 while the assembly is subjected to the usual vertical oscillation movement necessary for the success of the casting as well as to the thermo-mechanical stresses of a machine operating by thermal cycles imposed by the character necessarily sequential of the casting process.
• a material such as SiAION (Sialon) preferably doped with boron nitride, may be perfectly suitable.
• a circuit for injecting lost inert gas is provided between the riser 9 and the metal assembly 1 6-4.
• This circuit comprises an annular slot 28 formed at the raising interface 9 - metal assembly 1 6-4 and opening at one end along the inner periphery of the ingot mold and connected at its other end to a distribution chamber 29 supplied with argon by a 30 calibrated tubing, itself connected to a source of argon under pressure not shown.
• this resistant lower ring 26 is inevitably less insulating from heat than the upper part. There is therefore possible formation, in contact with its inner wall aligned 27 with that of the cooled ring 16, of a haze of premature parasitic solidification of the cast metal.
• This veil is an important factor of heterogeneity with regard to the solidification control process in the cooled metal assembly 16-4. It is for this reason that, in accordance with an advantageous implementation of the invention and already known moreover (FR-A-93 03871), an argon curtain is blown at the base of the extension 9 in order to break the parasitic solidification veil born on the ring 26 and allow a regular and frank start of solidification metal cast in contact with the cooled ring 1 6.
• the tendency to stick the crust 1 5 against the wall of the ingot mold is reduced by supplementing the known lubrication, carried out by injecting a lubricant through the copper element 4 (see by FR-A-91 01 551) by a vibration using an ultrasonic transducer and applied to the free end of the upper return 32 of the cooled element 4.
• This transducer may be of the "piezoelectric" type.
• the obliqueness of the direction of application of the ultrasound is not compulsory. However, it has the advantage of combining a vertical vibratory effect with a horizontal vibratory effect, both contributing to reducing the friction of the product poured into the mold.
• the invention applies to long products, such as flat products.
• the invention applies to the continuous casting not only of steel, but any other continuously castable metal and in particular metals with a lower melting point than steel, such as aluminum or copper.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Continuous Casting (AREA)
• Confectionery (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

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• 1996
  • 1996-04-05 FR FR9604305A patent/FR2747062B1/fr not_active Expired - Fee Related
• 1997
  • 1997-03-27 US US09/147,007 patent/US6050324A/en not_active Expired - Lifetime
  • 1997-03-27 JP JP53588597A patent/JP3727354B2/ja not_active Expired - Lifetime
  • 1997-03-27 CA CA002258109A patent/CA2258109C/fr not_active Expired - Lifetime
  • 1997-03-27 AT AT97919425T patent/ATE194786T1/de active
  • 1997-03-27 AU AU23908/97A patent/AU2390897A/en not_active Abandoned
  • 1997-03-27 ES ES97919425T patent/ES2150241T3/es not_active Expired - Lifetime
  • 1997-03-27 DK DK97919425T patent/DK0907439T3/da active
  • 1997-03-27 WO PCT/FR1997/000547 patent/WO1997037793A1/fr active IP Right Grant
  • 1997-03-27 DE DE69702611T patent/DE69702611T2/de not_active Expired - Lifetime
  • 1997-03-27 BR BR9708503A patent/BR9708503A/pt not_active IP Right Cessation
  • 1997-03-27 PT PT97919425T patent/PT907439E/pt unknown
  • 1997-03-27 EP EP97919425A patent/EP0907439B1/de not_active Expired - Lifetime
• 2000
  • 2000-09-25 GR GR20000402163T patent/GR3034474T3/el unknown

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