ELECTROMAGNETIC STIRRER ARRANGEMENT WITH CONTINUOUS CASTING OF STEEL BILLETS AND BLOOM
An electromagnetic stirrer arrangement includes a housing having a bottom opening and a top opening. An electromagnetic stirrer is positioned inside the housing. A modular mold assembly includes a mold, a water jacket, a top plate, a bottom plate and a plurality of rods connecting the top and bottom plates. The mold has an open top and an open bottom. The top plate is positioned proximate to the open top of the mold and the bottom plate is positioned proximate to the open bottom of the mold. The connecting rods extend between and securing together the top and bottom plate. The modular mold assembly can easily be replaced by inserting it into or removing from the housing.
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This application claims the benefit of U.S. provisional patent application No. 61/238,347 filed on Aug. 31, 2009, which is hereby incorporated by reference in its entirety.
FIELD OF THE INVENTIONThe field is the electromagnetic stirring of continuously cast steel and more particularly to an arrangement of an electromagnetic stirrer and a continuous casting mold assembly.
DESCRIPTION OF THE PRIOR ARTIn the production of continuously cast billets and blooms, two types of electromagnetic stirrer (EMS) arrangements with respect to continuous casting mold are commonly used, namely, internal and external.
In the internal EMS arrangement, the stirrer is positioned inside of a mold housing. The stirrer is thus in relatively close proximity to the casting mold the solidifying steel contained therein. With reference now to
In an external EMS arrangement, the stirrer is installed on the caster within its own enclosure which is arranged around the mold housing. The stirrer internal diameter is sized to accommodate the largest section size of the outside housing of the caster and remains installed on the caster during casting. With reference now to
In order to accommodate the mold housing 2 and the attached foot rolls 5, the internal diameter of stirrer housing 1 should be substantially large in comparison with that of the stirrer 3 arranged internally within the mold housing 4, as shown in
Though the above described molding assemblies have proven to be adequate, drawbacks persist. Thus, there is a need in the art for a new continuous casting arrangement with EMS.
SUMMARY OF THE INVENTIONAccording to one aspect of the present invention, an electromagnetic stirrer arrangement is disclosed. The electromagnetic stirrer arrangement includes a housing having a bottom opening and a top opening. An electromagnetic stirrer is positioned inside the housing. A modular mold assembly includes a mold, a top plate, a bottom plate and a plurality of rods connecting the top and the bottom plates. The mold has open top and bottom ends. The top plate is positioned proximate to the open top end of the mold and the bottom plate is positioned proximate to the open bottom end of the mold. The connecting rods extend between and securing together the top and bottom plate. The modular mold assembly is designed to allow replacement of a mold (insertion into or removal from) in the housing.
According to another aspect of the present invention, an electromagnetic stirrer arrangement is disclosed. The electromagnetic stirrer arrangement includes a housing having a bottom opening and a top opening. An electromagnetic stirrer is positioned inside the housing. A modular mold assembly includes a mold, a top plate, a bottom plate and a water jacket. The mold has open top and bottom ends. The top plate is positioned proximate the open top of the mold and the bottom plate is positioned proximate the open bottom of the mold. The water jacket is positioned around the mold to form a channel therebetween for directing cooling fluid over an exterior surface of the mold. The modular mold assembly is insertable and removable from the housing.
The internal diameter of an electromagnetic stirrer (EMS) affects the magnetic flux density value in a continuous casting mold. In turn, this affects stirring velocity in the melt induced by the magnetic field created by the EMS. At a constant apparent power input to the EMS (in kVA), magnetic flux density declines as the EMS internal diameter increases. This phenomenon is shown in the graph of
As seen from
With reference now to
The effect of an EMS internal diameter increase on the decline of magnetic flux density and stirring velocity may be counteracted by increasing power input to the EMS. However, due to practical limitations, this requirement often cannot be fulfilled, as the required power input is exponentially related to EMS internal diameter, as illustrated by
With reference now to
The modular assembly 120 includes the casting mold 102 which is fabricated from a copper alloy and has an open end on each side for delivery of liquid steel through the top opening T and withdrawal of the cast strand with solidifying core (not shown) through the bottom opening B. A water jacket 103 surrounds the mold 102 and forms a channel 104 between the outer surface of mold 102 and the inner surface of water jacket 103. Cooling water is directed through channel 104 to cool the mold 102.
The casting mold modular assembly 120 shown in
As shown in
A plate 116 extends outwardly from the top end of water jacket 103, circumferentially around mold 102. Plate 116 segments the interior of housing 101 to prevent mixture of incoming and outgoing cooling water flows (water flows represented by arrows). Upper plate 107 supports mold 102 by preventing axial displacement. Further supporting mold 102 is a plate 117 positioned below and flush with top plate 107. Plate 117 is coupled to the plate 107, surrounds mold 102 and is received in a groove 125 on the outer surface of mold 102. A protecting plate 113 of the mold housing 101 includes an opening substantially the same size as mold 102 and is secured to top plate 107. Protecting plate 113 protects top plate 107 from damage in event of liquid steel spillage.
With reference now to
It should be appreciated that the casting arrangement 100 described herein includes the features and advantages found in both internal and external EMS arrangements. Specifically, the “hybrid” arrangement provides the benefits of an internal EMS arrangement in terms of energy efficiency and metallurgical effectiveness while also enabling convenient and speedy casting mold changes, similar to an external EMS arrangement.
It should further be appreciated that, compared to an internal EMS arrangement, the casting arrangement 100 minimizes capital costs of equipment installation by reducing the number of mold housings and stirrers when the used with a multiple strand section caster. Further, operating costs are reduced compared to external EMS due to the smaller relative internal diameter of the EMS. Smaller internal diameter leads to reduced power requirements to attain operating values of magnetic flux density and frequency. Operating costs savings become especially significant when cast strand section sizes are within a wide range, e.g. 100 mm sq. to 200 mm sq. or greater.
It should also be appreciated that modular mold assembly 120 is configured to be fixed within the mold housing with mold section sizes based on stirrer design and operating parameters in order to assure maximal stirring effectiveness.
It should also be further appreciated that the casting arrangement 100, allows for convenient and relatively rapid replacement of casting mold 102 in accordance with the production schedule of casting operations by using the removable modular assembly 120. This assembly does not include the mold housing 101 and EMS 105 as they are common to the existing mold housing assemblies. Each mold modular assembly 120 can be exchanged for another one, if required, within the mold housing 101 equipped with the EMS 105.
The replacement procedure takes place at a mold preparation shop, in accordance with production schedule requirements. The amount of time and labor required for replacement of the modular mold assembly 120 is markedly reduced in comparison with that required for changing a mold in a typical internal EMS arrangement. Further, in applications with a multiple section size caster, the amount of mold housings to be used with the modular mold assembly is also drastically reduced in comparison with that required for prior art internal and external EMS arrangements. These advantages, combined with greatly reduced operating costs over the external EMS arrangement, result in substantial economic benefits in comparison with the existing conventional EMS arrangements.
It is to be understood that the description of the foregoing exemplary embodiment(s) is (are) intended to be only illustrative, rather than exhaustive, of the present invention. Those of ordinary skill will be able to make certain additions, deletions, and/or modifications to the embodiment(s) of the disclosed subject matter without departing from the spirit of the invention or its scope, as defined by the appended claims.
Claims
1. An electromagnetic stirrer arrangement comprising:
- a housing having a bottom opening and a top opening;
- an electromagnetic stirrer positioned inside said housing;
- a modular mold assembly including a mold, a top plate, a bottom plate and a plurality of connecting rods, said mold having an open top and an open bottom, said top plate being positioned proximate said open top of said mold and said bottom plate positioned proximate said open bottom of said mold, said rods extending between and securing together said top and bottom plate; and
- wherein said modular mold assembly is insertable and removable from said housing.
2. The electromagnetic stirrer arrangement of claim 1 wherein said plurality of connecting rods comprises four (4) rods positioned in an evenly spaced arrangement around said mold.
3. The electromagnetic stirrer arrangement of claim 1 wherein said plurality of connecting rods comprises eight (8) rods positioned in an evenly spaced arrangement around said mold.
4. The electromagnetic stirrer arrangement of claim 1 wherein said modular mold assembly further comprises a water jacket positioned between said plurality of connecting rods and said mold for directing cooling fluid over an exterior surface of said mold.
5. The electromagnetic stirrer arrangement of claim 1 wherein said bottom plate includes a central opening and said top plate includes a central opening, said mold being positioned within each said central opening.
6. The electromagnetic stirrer arrangement of claim 1 wherein said bottom plate central opening and said top plate central opening each include a groove and receives an o-ring therein, said o-ring engaging said central opening and an exterior surface of said mold.
7. The electromagnetic stirrer arrangement of claim 1 wherein said electromagnetic stirrer is supplied with an A.C. current at a frequency of 1 to 10 Hz and intensity between 50 and 550 Amps.
8. The electromagnetic stirrer arrangement of claim 1 wherein said housing extends between said top plate and said bottom plate to encapsulate said mold.
9. An electromagnetic stirrer arrangement comprising:
- a housing having a bottom opening and a top opening;
- an electromagnetic stirrer positioned inside said housing;
- a modular mold assembly including a mold, a top plate, a bottom plate and a water jacket, said mold having an open top and an open bottom, said top plate being positioned proximate said open top of said mold and said bottom plate positioned proximate said open bottom of said mold, said water jacket positioned around said mold to form a channel therebetween for directing cooling fluid over an exterior surface of said mold; and
- wherein said modular mold assembly is insertable and removable from said housing.
10. The electromagnetic stirrer arrangement according to claim 9 further comprising a plurality of connecting rods extending between and securing together said top and bottom plate.
11. The electromagnetic stirrer arrangement according to claim 10 wherein said plurality of connecting rods comprises four (4) rods positioned in an evenly spaced arrangement around said mold.
12. The electromagnetic stirrer arrangement according to claim 10 wherein said plurality of connecting rods comprises eight (8) rods positioned in an evenly spaced arrangement around said mold.
13. The electromagnetic stirrer arrangement of claim 9 wherein said bottom plate includes a central opening and said top plate includes a central opening, said mold being positioned within each said central opening.
14. The electromagnetic stirrer arrangement of claim 10 wherein said bottom plate central opening and said top plate central opening each include a groove and receives an o-ring therein, said o-ring engaging said central opening and an exterior surface of said mold.
15. The electromagnetic stirrer arrangement of claim 11 wherein said electromagnetic stirrer is supplied with an A.C. current at a frequency of 1 to 10 Hz and intensity between 50 and 550 Amps.
16. The electromagnetic stirrer arrangement of claim 9 wherein said housing extends between said top plate and said bottom plate to encapsulate said mold.
Type: Application
Filed: Aug 26, 2010
Publication Date: Mar 3, 2011
Applicant: ABB INC. (Saint-Laurent)
Inventors: David A. Domanski (Brooklin), Leonid Beitelman (Thornhill), Christopher P. Curran (Courtice), Thomas P. Mulcahy (Whitby)
Application Number: 12/869,266
International Classification: B22D 27/02 (20060101);