CRYSTALLIZER FOR CONTINUOUS CASTING AND METHOD FOR ITS PRODUCTION

Abstract

Crystallizer for continuous casting comprising a tubular body (11) having at least one wall (12) which defines a through longitudinal casting cavity (13) and a plurality of longitudinal grooves (14) made at least on one part of the wall (12) and open toward the outside thereof. A covering binding (15) is associated to the external surface of the wall (12) to close the longitudinal groves (14) and thus obtain corresponding cooling channels (17) configured to make a cooling liquid flow inside them.

Claims

1. Crystallizer for continuous casting, comprising: a tubular body having at least one wall which defines a through longitudinal casting cavity and a plurality of longitudinal grooves made at least on one part of said at least one wall and open toward the outside thereof, wherein a covering binding, comprising one or more overlapping layers of fiber material impregnated with a polymer material, which define one or more bands, is wound around an external surface of said tubular body and irremovably attached thereto by a polymerization thereof, so as to create an indivisible whole between the at least one wall with the longitudinal grooves and the covering binding, wherein the covering binding is in direct contact with one of: the external surface of the at least one wall and closes the longitudinal grooves, or at least one of: a metal layer, a lamina, or a plate that in its turn is in direct contact with the external surface of the at least one wall and closes the longitudinal grooves, to define a corresponding plurality of cooling channels, wherein the crystallizer has an internal conicity, wherein the covering binding is wound tightly around the external surface of the tubular body in a direction mainly transverse to its longitudinal direction limiting the deformation and movement of the at least one wall to maintain the internal conicity, while allowing longitudinal dilation due to heat phenomena, wherein said covering binding has a variable thickness along the longitudinal extension of said tubular body to define at least an upper portion, substantially comprising the meniscus area during the casting, defining a thickened zone having a thickness comprised between 1.1-1.25 the thickness of a non-thickened zone in a lower portion of the tubular body.

2. Crystallizer as in claim 1, wherein said one or more bands are made using at least one fiber impregnated, or pre-impregnated, with polymer material.

3. Crystallizer as in claim 1, wherein said fiber is chosen from a group comprising carbon fibers, glass fibers, aramid fibers or combinations thereof, and said polymer is chosen from a group comprising polyamide, epoxy or polyester resins.

4. Method to obtain a crystallizer for continuous casting, comprising: a step of making a tubular body having at least one wall which defines a through longitudinal casting cavity and a plurality of longitudinal grooves made at least on one part of an external surface of said at least one wall and open toward the outside thereof, a step in which a covering binding, comprising one or more overlapping layers of fiber material impregnated with a polymer material, which define one or more bands, is wound around said external surface of said at least one wall and then said polymer material is polymerized in order to solidly attach said covering binding to said wall, in which the polymerization of said polymer material comprises: a curing step during which said crystallizer is heated to a temperature comprised between 30° C. and 120° C. and kept at this temperature for a period comprised between 20 and 200 minutes, and a post-curing step during which said crystallizer is heated to a temperature comprised between 80° C. and 200° C. and kept at this temperature for a period comprised between 60 minutes and 1200 minutes.

5. Method as in claim 4, wherein, in said curing step, said crystallizer is heated to a temperature comprised between 70° C. and 100° C. and kept at this temperature for a period comprised between 120 minutes and 360 minutes.

6. Method as in claim 4, wherein, in said post-curing step, said crystallizer is heated to a temperature comprised between 100° C. and 150° C. and kept at this temperature for a period at least about 360 minutes.

7. Method as in claim 4, wherein, before the winding of said one or more overlapping layers of fiber material, there is a step of filling said longitudinal grooves with disposable material, to deposit a metal layer on the external surface of said at least one wall by means of electrolytic deposition techniques, in order to close said longitudinal grooves, and a further step of removing said disposable material from said longitudinal grooves so as to define corresponding cooling channels.

8. Method as in claim 4, wherein, before the winding of said one or more overlapping layers of fiber material, there is a step of closing said longitudinal grooves with at least one lamina made of a fiber-reinforced polymer material to define a plurality of cooling channels, and wherein, during said winding, said fiber material is wound around and in direct contact with said lamina made of fiber-reinforced polymer material.

9. Method as in claim 4, wherein, before the winding of said one or more overlapping layers of fiber material, there is a step of closing said longitudinal grooves with at least a plate associated to the external surface of said at least one wall so as to define a corresponding plurality of cooling channels.

10. Method as in claim 4, wherein said fiber material is wound around said wall at a winding angle comprised between 0° and 10°, preferably between 0° and 5°, with respect to the perpendicular to the axis of longitudinal development of the crystallizer.

11. Method as in claim 4, wherein said covering binding comprises a band made using at least a fiber impregnated or pre-impregnated with glue or polymer resin, said covering binding having a volumetric ratio of fibers of 60%, and glue or polymer resin of 40%.

12. Method as in claim 4, wherein during the winding of said fiber material, fibers making up said covering binding are wound at a controlled tension between 1N and 50N.

13. Method as in claim 4, wherein said covering binding is applied using the filament winding technique.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] These and other characteristics of the present invention will become apparent from the following description of some forms of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

[0057] FIG. 1 is a perspective and schematized view of a crystallizer for continuous casting according to a first form of embodiment of the present invention;

[0058] FIG. 2 is an enlarged detail of the crystallizer in FIG. 1;

[0059] FIG. 3 is a perspective and schematized view of a detail of a crystallizer according to a second form of embodiment of the present invention;

[0060] FIG. 4 is a schematized view of a detail of a crystallizer according to a third form of embodiment of the present invention;

[0061] FIGS. 5 and 6 are schematized views of possible variants of the crystallizer according to the present invention.

[0062] To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one form of embodiment can conveniently be incorporated into other forms of embodiment without further clarifications.

DETAILED DESCRIPTION OF SOME FORMS OF EMBODIMENT OF THE PRESENT INVENTION

[0063] With reference to FIGS. 1 and 2, a crystallizer 10 for continuous casting according to the present invention, in a first form of embodiment, comprises a tubular body 11 with a wall 12, for example made of copper or its alloys, which defines a through longitudinal casting cavity 13. The thickness of the wall 12 is for example comprised between 10 mm and 50 mm.

[0064] There is a plurality of longitudinal grooves 14 on at least an external part of the wall 12. Each longitudinal groove 14 is open toward the outside of the wall 12.

[0065] A covering binding 15, which in this case comprises one or more layers of a band 16 of fiber, impregnated or pre-impregnated with a polymer resistant to high temperatures (that is, equal to or higher than 100° C.), is in direct contact with the external surface of the wall 12 and closes the longitudinal grooves 14 from the outside. In this way corresponding channels 17 are made, configured to make a cooling liquid, for example water, flow inside them. In this specific case, it is provided that the band 16 defines a plurality of layers wound on the external surface of the wall 12 of the crystallizer 10.

[0066] In a second form of embodiment, a crystallizer 110 (FIG. 3) according to the present invention comprises, interposed between the covering binding 15 and the wall 12, a metal layer 18 made with electrolytic deposition techniques, for example as described in the application for a patent of industrial invention UD2013A000013 cited above.

[0067] In this case, it is the metal layer 18 that hermetically closes the longitudinal grooves 14 from the outside of the wall 12 and defines the plurality of cooling channels 17.

[0068] Therefore, in this second form of embodiment, the covering binding 15 is in direct contact with the metal layer 18, in order to make rigid the whole made up of the latter and the wall 12. This allows to have a very contained thickness of the metal layer 18, for example in the range of one or two millimeters. The covering binding 15 in this case has a containing function of the metal layer 18 and guarantees the seal of the latter even at high working pressures of the cooling fluid circulating in the channels 17.

[0069] According to the form of embodiment in FIG. 6, the metal layer 18 can be replaced by a lamina 23 made of a fiber-reinforced polymer material which, closing the longitudinal grooves 14 from the outside, defines the corresponding plurality of cooling channels 17. The covering binding 15 is wound intimately in direct contact with the lamina 23 to make rigid the whole constituted by the wall 12 and the lamina 23.

[0070] According to a third form of embodiment, a crystallizer 210 (FIG. 4) according to the present invention comprises a tubular body 211 provided with a plurality of walls 212 defining a longitudinal casting cavity 213. The longitudinal grooves 14, open toward the outside, are made on the external surface of the walls 212, by removing material. At least one plate 219, in this specific case four plates 219, are associated to the external surface of the tubular body 211, for example welded or glued, and are provided to close the longitudinal grooves 14 made on the walls 212 of the tubular body 211 from the outside and to define the cooling channels 17.

[0071] The plates 219 can be associated to the external surface of the tubular body 211, for example, by braze welding or structural gluing, in the same way as described in the Italian application for a patent of industrial invention UD2012A000193 in the name of the Applicant.

[0072] In this case too, as in the first form of embodiment, the covering binding 15 is in direct contact with the surface of the plates 219 that is external during use, to reinforce them and increase the secure seal of the braze welding.

[0073] Forms of embodiment of the present invention provide that the covering binding 15 has a constant thickness along the longitudinal extension of the tubular body 11, 211.

[0074] Other forms of embodiment, one of which is shown in FIG. 5, provide that the covering binding 15 is provided with a thicker portion 20 that has a greater thickness than the thickness along the longitudinal extension of the tubular body 11 or 211. In this way it is possible to generate zones of the crystallizer 10 with variable resistance and rigidity along its longitudinal extension that are determined, for example, depending on a variable development of the pressure of the cooling fluid in the cooling channels 17 or on different conditions of mechanical and/or heat stress to which it can be subjected during normal use.

[0075] In particular, the thickness of the covering binding 15, when completely wound, is greater in an upper-zone, substantially comprising the meniscus area during the casting, than along the entire length of the crystallizer 10, that is a lower non-thickened zone.

[0076] The covering binding 15 in the thickened zone has a thickness comprised between 1.1-1.25 times the thickness of the non-thickened zone. Merely by way of example, the covering binding 15 in the thickened zone has a thickness comprised between 1.1 mm and 10 mm.

[0077] According to other forms of embodiment of the present invention, shown for example in FIG. 6, mechanical workings, for example to define circumferential seatings 21 for housing sealing rings or holes 22 for the insertion of break-pins, can be made on the covering binding 15.

[0078] In particular, at the end of the operation of winding the covering binding 15, and before the complete polymerization of the polymer, a hole 22 is made through the layer of fiber material partially affecting the thickness of the crystallizer 10.

[0079] A retaining element, for example a retaining key, 24 is inserted into the hole 22 to bind the fibers to the crystallizer 10.

[0080] The hole 22 is then covered with a patch 25 made of impregnated fibers, for example carbon fibers, so that the retaining element 24 cannot come out and the fiber structure is cured as described above.

[0081] This retaining element 24 is intended to prevent any sliding of the fibers once cured to the crystallizer 10.

[0082] The method for producing each of the crystallizers 10, 110, 210 for continuous casting described heretofore comprises a step in which the tubular body 11, 211 is made, with the wall 12 or walls 212 that define the longitudinal cavity 13, 213 and the plurality of longitudinal grooves 14, made for example by removing material, such as milling, at least on one part of the wall 12 or walls 212, and open toward the outside thereof.

[0083] The method also comprises a step in which a covering binding 15, as described heretofore, is associated to the external surface of the wall 12 or walls 212.

[0084] In particular, the binding 15 comprises the band 16 made with one or more overlapping layers, using at least a fiber impregnated or pre-impregnated with a polymer resistant to high temperatures, as indicated above, that is chosen for example from a group comprising polyamide, epoxy or polyester resins.

[0085] It can be provided, for example, that the wall 12 or walls 212 is or are installed on a winding machine, for example by means of clamps or specific equipment to allow the subsequent winding operation of the fibers around it.

[0086] The fibers can be polymerized in different curing passes, for example a curing, or solidification, step at a temperature between 30° C.-120° C., preferably between 70° C. and 100° C., for a period comprised between 20-400 minutes, preferably between 2 hours and 360 minutes, more preferably around 240 minutes, followed by a post-curing, or hardening, at a temperature between 80° C.-200° C., preferably between 100° C. and 150° C., for a period comprised between 60-1200 minutes, preferably at least about 360 minutes, more preferably around 480 minutes, depending on the resin applied.

[0087] For example, the covering binding 15 can be applied using the filament winding technique.

[0088] It is clear that modifications and/or additions of parts may be made to each of the crystallizers 10, 110, 210 for continuous casting as described heretofore, without departing from the field and scope of the present invention.

[0089] It is also clear that, although the present invention has been described with reference to some specific examples of embodiments, a person of skill in the art shall certainly be able to achieve many other equivalent forms of crystallizer for continuous casting and/or other methods to make them, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.