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
  • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
  • B22D11/0637—Accessories therefor
  • B22D11/0665—Accessories therefor for treating the casting surfaces, e.g. calibrating, cleaning, dressing, preheating
  • B22D11/0671—Accessories therefor for treating the casting surfaces, e.g. calibrating, cleaning, dressing, preheating for heating or drying
• • 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
  • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
  • B22D11/0622—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by two casting wheels
  • B22D11/0625—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by two casting wheels the two casting wheels being immersed in a molten metal bath and drawing out upwardly the casting strip

Definitions

• the invention concerns a continuous casting device to produce strips of steel from molten metal and a casting method which can be employed with this device, wherein the molten metal is fed from below and the slab or strip being formed is therefore unloaded from above.
• the invention is applied particularly, but not only, to produce steel strip with low and medium carbon content and with thicknesses varying in the range of 2.5 to 10 mm.
• the state of the art includes equipment for the continuous casting of molten metal so as to obtain products of variable shape and size. It includes, for example, the use of ingot molds whose section defines the shape of the ingot or billet which is then sent for rolling to reduce the thickness.
• rollers It also includes the use of equipment with large diameter, facing rollers to obtain strip to be sent to subsequent processing; the rollers have at least a section of surface which is cooled so as to determine at least a partial solidification of the skin of the strip leaving the rollers.
• JP-A-05245594 JP-A- 01284461
• JP-A-04009251 JP-A-63093450
• JP-A-60137553 JP-A-05245594
• the molten metal is cast from the top and extracted from the bottom, which in some cases can cause operating problems, such as the bulk involved, the movement of the equipment, the management of the slab or strip extracted, or other problems.
• the present Applicant has designed, tested and embodied this invention to overcome this shortcoming of the state of the art.
• the purpose of the invention is to provide a simple, functional and extremely efficient solution which will make possible the continuous casting, using rollers, of any type of steel, and particularly steels with low carbon content, yet ensuring high standards of quality both of the surface and internal .
• Another purpose of the invention is to achieve a method to obtain the strip which emphasises the main purpose.
• the rollers are arranged above a container of liquid metal and the strip is extracted upwards .
• each roller of the casting device is immersed inside the container of liquid metal, defined on two sides by the rollers themselves, and the ribbons of liquid metal gathered by each roller are coupled and joined to each other to form the strip, substantially in the position where the two rollers are nearest.
• the surface of the rollers for at least part of the outer arc of contact with the liquid metal, is kept heated by the appropriate means outside the roller itself.
• internal heating means are used.
• both internal and external heating means are used.
• the surface temperature of the rollers is taken to at least 700°C, advantageously 750°C or more.
• the liquid metal at its melting temperature does not suffer any heat shock which might determine the formation of cracks or micro-fissures in the surface, since the heat exchange which creates the first solidified skin of the strip is reduced.
• the surface of the rollers is cooled, however, for the whole, or at least for a substantial part, of the arc placed in contact with the liquid metal; this is to encourage the formation of a first, at least partly solidified skin.
• this cooling is intense along the whole surface of the roller which cooperates with the bath of molten metal.
• the cooling is progressive, and reaches its maximum intensity at a desired distance from the point of contact between the roller and the liquid metal .
• the strip is therefore obtained from the union of the two ribbons of liquid metal which are formed on the cooled surface of the rollers and can be extracted through the space defined by the rollers themselves.
• the system to heat the surface of the rollers is obtained with a plurality or induction resistors, which have a high heating efficiency, for example arranged outside in an arc in cooperation with the arc of the outer roller which is in contact with the liquid metal.
• the heating system is obtained with a plurality of resistors arranged on the circumference inside the roller; they can be activated in a controlled manner according to the circumferential position of the roller with respect to the liquid metal and are separated from each other by respective cooling water channels .
• the roller is of the type where the cooling liquid circulates inside.
• the liquid metal is supplied to the roller device from below and the cast product, in the form of a strip with the skin at least partly solidified, comes out in an upwards direction before being extracted and possibly returned to the horizontal by the appropriate devices .
• the attached Figure is given as a non-restrictive example and shows a preferred embodiment of the casting device and method according to the invention.
• the continuous casting device 10 with counter-rotating rollers 11a, lib is shown in the case of casting from below in an upwards direction where the lower part of the rollers 11a and lib is immersed in a container or tundish 12 to contain the liquid metal 13. As they rotate, the two rollers 11a and lib are immersed inside the tundish 12 and, due to the cooling of their surface in the respective ideal sector A and A' of contact with the liquid metal 13, cause the formation of two ribbons 14a and 14b, which have an at least partly solidified skin.
• the ribbons 14a and 14b join together at the kissing point 15 to form a strip 16 which, after a possible pressing at the point of maximum proximity of the rollers 11a and lib, emerges from the rollers and is extracted and possibly returned to the horizontal by an extraction and straightening assembly 17.
• first heating system 18 comprising a plurality of induction resistors 19 arranged in an arc in cooperation with the periphery of the relative roller 11a, lib and a second heating system 20 comprising resistors 21 arranged inside the relative roller 11a, lib which can be activated selectively.
• the resistors 21 are activated as they gradually leave the exit limit M of the relative sector A, A' and are disactivated before they reach the entrance limit N to the sector A, AX
• the resistors 21 are separated by cooling channels where the distribution of the water is activated in the sector A and A' and disactivated in the remaining sector of the roller. According to a variant which is not shown here, in place of the induction resistors 19 there are burners with a controlled flame.
• the surface of the rollers is heated by means of radiancy systems using infra-red rays.
• the heating systems 18 and 20 serve to bring the surface of the rollers 11a and lib, while they are in rotation, to a temperature of at least 700°C, advantageously 750°C and more, at the moment when they come into contact with the liquid metal 13, in such a way as to reduce the heat exchange between the surface of the roller and the first forming skin, and therefore the relative heat shock.
• the cooling system is activated and therefore the surface temperature is returned to a much lower value, in such a way as to allow the at least partial solidification of the skin of the strip 16 in correspondence with the outlet of the rollers 11a, lib.
• the device 10 makes it possible to obtain strip 16 from low-alloy steels with a low or medium carbon content, at the same time obtaining a high standard of quality.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Continuous Casting (AREA)
• Rolls And Other Rotary Bodies (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=11355469

Family Applications (1)

Country Status (5)

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Family Cites Families (7)

• 1997
  • 1997-09-10 IT ITGO970017 patent/IT1304333B1/it active
• 1998
  • 1998-07-24 EP EP98932450A patent/EP1124659A1/en not_active Withdrawn
  • 1998-07-24 WO PCT/IB1998/001128 patent/WO1999012677A1/en not_active Application Discontinuation
  • 1998-07-24 CA CA002303155A patent/CA2303155A1/en not_active Abandoned
  • 1998-07-24 AU AU82371/98A patent/AU733520C/en not_active Ceased

Non-Patent Citations (1)

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