Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
  • B22D41/50—Pouring-nozzles

Definitions

• the present invention relates to a submerged entry nozzle to pour molten steel in the ingot moulds for slabs.
• submerged entry nozzles hereinafter also designated as SENs, having a simply tubular shape with two ports obtained on the two sides of the lower end, are used in the continuous casting of slabs.
• this solution is coupled to the slide gate regulation system, in other cases to the stopper system, in the inlet part for the molten steel.
• the present invention thus intends to overcome the drawbacks discussed above displayed by the known submerged entry nozzles, by means of an entry nozzle that produces a higher quality casting product. Summary of the invention It is the primary object of the present invention to provide a submerged entry nozzle that solves all of the fluid dynamics and process problems listed above, in a simple and effective manner. This object is achieved by an entry nozzle for molten steel, adapted to be used submerged in an ingot mould for slabs, comprising an elongated tubular body, defining a longitudinal axis and a vertical symmetry plane passing through the longitudinal axis, having
• a second opening at the second end of the tubular body for the outlet of the molten steel having an outlet direction substantially parallel to the longitudinal axis and a passage section having a surface such as to allow a steel flow rate much lower than the flow rate of the side ports, wherein there are provided, in proximity of the second end of the tubular body and within the latter, two surfaces tilted with respect to the longitudinal axis and converging towards the second end, the ideal or actual intersection line of said tilted surfaces laying on a vertical symmetry plane.
• the SEN according to the present invention ensures a stable and balanced flow and is capable of ensuring an optimal process that does not display the problems previously set forth.
• Figure 1 shows a view of the entry nozzle according to the invention
• Figure 2 shows a side view of the entry nozzle in Fig. 1
• Figure 3 shows an axial section of the entry nozzle in Fig. 1 along a vertical plane
• Figure 4 shows an axial section along plane C-C of a first embodiment of the entry nozzle in Fig. 3
• Figure 5 shows an axial section along plane C-C of a second embodiment of the entry nozzle according to the invention
• Figure 6 shows a section which is perpendicular to the longitudinal axis, along plane A-A, of the entry nozzle in Figure 5;
• Figure 7 shows a section of the casting product in the ingot mould with the profile of the thickness of the skin during solidification with an entry nozzle of the state of the art
• Figure 8 shows a section of the casting product in the ingot mould with the profile of the thickness of the skin during solidification with an entry nozzle according to the invention.
• the SEN has an elongated body having a tubular form 2 that preferably displays a longitudinal symmetry axis X.
• Such an elongated tubular body 2 is provided with a first opening 3 at a first end, that forms the inlet for the molten steel, cooperating, for instance, with a tundish or an undertundish or another appropriate container, depending on the continuous casting plant in which the entry nozzle is used.
• This passage may be opened or closed, according to the operative requirements, di- rectly or indirectly by means of a stopping and/or control device for the flow, as for instance a slide gate system or a system incorporating a stopper.
• the tubular body 2 is provided with a central hole 4, having a preferably but not exclusively circular section, the axis of which is parallel to the longitudinal axis X or, preferably, coincident therewith.
• Two outlet side ports or mouths 5, 6 for the steel which is poured in the ingot mould are provided at the end of the tubular body 2, opposite to that end where the first opening 3 for the inlet of steel is positioned. During the casting process, these ports remain submerged within the molten steel bath under the level of the meniscus.
• the ports 5, 6, having the same shape and section, are obtained in the side walls of the tubular body 2. These two ports 5, 6 have their side walls, which determine the outlet flow of the steel, slightly diverging towards the outside of the tubular body, as shown in Fig. 1 and in Fig. 6. Arrows F1 and F2 indicate the average outlet direction of the steel flow respectively from the ports 5 and 6 and substantially lay on a same vertical symmetry plane of the tubular body 2 passing through the longitudinal symmetry axis X of the tubular body itself.
• the side ports 5 and 6 have a trapezoidal shape with the shorter base of the tra- pezium placed downwards, in order to insert themselves in the tapered shape of the tip of the tubular body 2 of the entry nozzle 1.
• the ports 5 and 6 are divergent along the outlet direction of the flow from the ports themselves both in vertical section ( Figure 4) and in horizontal section ( Figure 6), maintaining a trapezoidal section having a progressively increasing surface from the axis X of the tubular body towards the outer surface of the tubular body 2.
• the following angles are defined:
• - "Y" is the angle that the tangent to the external edge of the upper connector 8 of the port 5, 6 forms with the axis X;
• the inside of the tube is defined by two planes 9, 10 tilted with respect to the longitudinal axis X and converging towards the tip of the tubular body 2.
• the ideal or actual intersection line of these two planes 9, 10 lays on the symmetry plane Y of the tubular body 2.
• a further opening, provided on the bottom 4' of the entry nozzle 1 has an outlet direction of the steel flow substantially aligned with the longitudinal axis X of the tubular body 2. It may have a passage section, which is advantageously circular, preferably obtained in the form of a calibrated hole 1 1 , with a much smaller surface than the passage section surface of the central hole 4 of the tubular body 2 and of the side mouths 5, 6.
• This further opening serves to stabilise the pressure cell which is generated by the flow when it impacts the bottom of the SEN, thus ensuring the equivalence of the flow rate of the flow outflowing from the side ports 5, 6 and avoiding the transversal huntings of the flow within the SEN.
• a minimum flow rate of steel flows out through said calibrated hole 1 1 , in virtue of the small size thereof.
• the outer lower edge 5', 6' of the mouths 5, 6 is placed beyond the inner bottom line 4' of the tubular body in the direction of the tip.
• this SEN is capable of giving a complete and stable fluxing in the terminal part of the SEN.
• the flow through the ports 5, 6 is balanced, stable and uniform.
• the opening made in the lower closure or bottom of the SEN may also have the shape of a longitudinal slot or eye 12, instead of a circular hole, but having a longitudinal extension not exceeding the inner diameter of the hole 4 of the tubular body 2.
• said opening (calibrated hole 1 1 or longitudinal slot 12) is not a supply port for the flow in the crystalliser having a flow rate comparable to that of the side mouths 5, 6, but rather serves to carry out the outlet of a minimum amount of flow rate which does not change the flow course within the crystalliser but serves to give stability to the flow within the SEN.
• the percent ratio between the passage section surface of said opening and the passage section surface of the central hole 4 of the tubular body 2 is comprised between 1 and 20%;
• the percent ratio between the passage section surface of said opening and the sum of the outer trapezoidal section surfaces of the side mouths 5, 6 is comprised between 1 and 25%;
• the percent ratio between the flow rate outflowing through said opening and the flow rate through the central hole 4 is comprised between 1 and 30%.
• said opening is a calibrated hole 1 1 :
• the percent ratio between the passage section surface of the calibrated hole 1 1 and the passage section surface of the central hole 4 of the tubular body 2 is comprised between 1 and 5%, preferably equal to about 2,5%;
• the percent ratio between the passage section surface of the calibrated hole 1 1 and the sum of the outer trapezoidal section surfaces of the side mouths 5, 6 is comprised between 1 and 6%, preferably equal to about 3%;
• the percent ratio between the flow rate outflowing through the calibrated hole 11 and the flow rate through the central hole 4 is comprised between 1 and 4%, preferably equal to about 2%.
• the percent ratio between the passage section surface of the longitudinal slot 12 and the passage section surface of the central hole 4 of the tubular body 2 is comprised between 10 and 20%, preferably equal to about 16%;
• the percent ratio between the passage section surface of the longitudinal slot 12 and the sum of the outer trapezoidal section surfaces of the side mouths 5, 6 is comprised between 15 and 25%, preferably equal to about 20%.
• the percent ratio between the flow rate outflowing through the longitudinal slot 12 and the flow rate through the central hole 4 is comprised between 10 and 30%, preferably equal to about 12%.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
• Glass Compositions (AREA)
• Mechanical Sealing (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=38556358

Family Applications (1)

Country Status (3)

Cited By (2)

Citations (2)

• 2007
  • 2007-01-22 IT ITMI20070083 patent/ITMI20070083A1/it unknown
• 2008
  • 2008-01-22 EP EP08708061.0A patent/EP2111316B1/en not_active Not-in-force
  • 2008-01-22 WO PCT/EP2008/050695 patent/WO2008090146A1/en not_active Ceased

Patent Citations (3)

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