Stopper rod and method for inducing rotational flow of molten metal

Abstract

A plug rod (100) for controlling a flow rate of molten metal and for causing a swirling flow of molten metal, the plug rod (100) comprising a rod-shaped plug body (101) extending along a central longitudinal axis (L) from a first end (105) to a second end (107), the rod-shaped plug body (101) comprising a nose (103) at the second end (107) wherein the nose (103) provides an outer surface; a chamber (109) extending within the plug body (101) along the central longitudinal axis (L) from the first end (105) towards the second end (107) and terminating away from the second end (107); at least one channel (111), preferably a plurality of channels (111), provided on the outer surface of the rod-shaped plug body (101) and at least partially on the outer surface of the nose (103), and extending at least partially around the central longitudinal axis (L) and advancing in the direction of the central longitudinal axis (L); and a gas supply connection means (123) connecting the chamber (109) and each of the at least one channel (111).

Description

Technical Field

[0001] The present invention relates to a stopper rod and a method for inducing a rotational flow of molten metal. Background Art

[0002] In the continuous casting of molten metal, in particular molten steel in a continuous casting installation, the molten metal is provided in a container, in particular in the form of a ladle or a tundish.

[0003] An outlet is provided at the bottom of a container in which molten metal is provided, and the molten metal in the container can be cast into a downstream mold located below the container through the outlet.

[0004] At the bottom of the tundish, such an outlet is provided in the form of a tundish nozzle. This tundish nozzle may be provided in the form of a submerged nozzle (SEN) or a submerged entry shroud (SES). Molten metal from the tundish may be cast into the mould through the tundish nozzle. A stopper rod (also called a plug) is provided to control the amount of molten metal flowing through the outlet, in particular through the tundish nozzle.

[0005] These stopper rods have a rod-shaped stopper body which is aligned vertically above the outlet, for example above the tundish nozzle. At its upper end, a metal rod is attached to the stopper rod, whereby the metal rod in turn is connected to a lifting device (which is part of the stopper rod control system), via which the stopper rod can be lifted and lowered vertically. At its lower end, the stopper rod has a nose, also called a "stopper nose". By lowering the stopper rod, the nose can be guided against the outlet in such a way that the outlet can be completely closed by the nose and the molten metal cannot flow through the outlet.

[0006] Furthermore, the stopper rod can be lifted vertically so that it opens the outlet in a controlled manner and the molten metal can flow through the outlet. Thus, with the help of the stopper rod, the flow rate of the molten metal through the outlet (eg, the tundish nozzle) can be controlled.

[0007] During the casting process, non-metallic particles present in the molten metal may be deposited on the refractory material, in particular on the stopper rod, the outlet or the submerged nozzle located downstream of the tundish nozzle. More specifically, these particles may be aluminum oxide particles present in the molten metal. This deposition of non-metallic material on the refractory material is also called "clogging" and adversely affects the properties of the refractory material. As is known, in order to suppress clogging, an inert gas, in particular argon or nitrogen, may be introduced into the molten metal in the region of the nose of the stopper rod.

[0008] Universal stopper rods with a gas outlet in the nose area are described, for example, in EP 2 067 549 A1, EP 2 189 231 A1, EP 2 233 227 A1 or EP 3 705 204 A1, EP 1 736 260 A1, JP H03 110 048 A, EP 3 903 963 A1, EP 3 939 717 A1, KR 20140082497 A, CN 113 547 112 A, EP 3 928 891 A1, CN 112 743 070 A, KR 101 794 598 B1.

[0009] In addition to suppressing blockages, another goal in continuous casting is to achieve high-quality steel without non-metallic inclusions and defects. It has been shown that causing a rotational movement of the molten metal (vortex motion or vortex flow) inside the tundish nozzle, for example, can improve the quality of the cast steel. This vortex flow is often achieved with the aid of a magnetic field (see, for example, EP 3 597 328 A1). However, this method requires a high investment in such equipment, requires continuous maintenance, and consumes a lot of energy during operation. Other attempts to achieve vortex flow with the aid of a spiral structure on the plug rod are known (see, for example, KR101499201B1). EP1 106 286 A1 discloses a device used as a vortex generator, which needs to be positioned in the inlet area of ​​the nozzle.

[0010] The inventors have realised that in order to achieve a proper rotational flow induced by the stopper rod, there must be at least one channel, such as a helical channel, on the surface of the stopper rod in the region of the stopper rod nose and there must be gas injection directly into the helical channel. Summary of the invention

[0011] It is therefore an object of the present invention to provide a stopper rod and a method for inducing a rotational flow of molten metal.

[0012] This object is achieved by a stopper rod according to claim 1 and a method according to claim 13 .

[0013] The core idea of ​​the invention is based on the finding that a swirling flow of the molten metal flowing in the tundish nozzle is induced by gas injection through at least one channel on the outer surface of the stopper rod, the at least one channel being at least partially arranged on the nose of the stopper rod, extending at least partially around a central longitudinal axis and advancing in the direction of the longitudinal axis (that is to say the channel is deflected in the longitudinal direction).

[0014] In a first aspect of the invention, this object is achieved by a stopper rod for controlling the flow of molten metal and for inducing a swirling flow of the molten metal, the stopper rod comprising:

[0015] Rod-shaped plug:

[0016] The rod-shaped plug body extends along a central longitudinal axis (L) from a first end to a second end, and the rod-shaped plug body includes a nose portion located at the second end.

[0017] in,

[0018] The nose provides an exterior surface;

[0019] A chamber which:

[0020] Extending within the plug body along the central longitudinal axis (L) from the first end toward the second end and terminating away from the second end;

[0021] At least one channel (ie, one or more channels), preferably a plurality of channels (ie, more than one channel / at least two channels):

[0022] (each of the at least one channel / each of the one or more channels) is disposed on the outer surface of the rod-shaped plug body and at least partially on the outer surface of the nose, and

[0023] (each of the at least one channel / each of the one or more channels) extends at least partially around the central longitudinal axis (L), and

[0024] (each of the at least one channel / each of the one or more channels) advances in the direction of the central longitudinal axis (L);

[0025] A gas supply connection device, the gas supply connection device:

[0026] The chamber and each of the at least one channel (in other words: each of the one or more channels) are connected.

[0027] The basic element of this plug rod for controlling the flow of molten metal and for causing the swirling flow of molten metal is at least one (i.e., one or more) channel, which is arranged on the outer surface of the rod-shaped plug body and at least partially on the outer surface of the nose, and extends at least partially around the central longitudinal axis (L), and advances in the direction of the central longitudinal axis (L), for example, on a spiral path or along other inclined / deflected paths. At least one channel is arranged on the outer surface of the rod-shaped plug body and at least partially on the outer surface of the nose, which means that the at least one channel (each of the channels) has a portion aligned on the outer surface of the nose, and the rest of each corresponding channel can be aligned on the outer surface of the plug body (in the area adjacent to the nose). Preferably, multiple channels are provided. It is particularly preferred to provide an even number of channels, wherein the paired channels are arranged to be opposite to each other about the longitudinal axis. From here on, multiple channels may also be referred to as channels, but are not limited to multiple channels. To avoid doubt, multiple channels include any number of channels, such as one or more channels.

[0028] The respective gas supply connection means are used to cause gas to enter each of the at least one channel from the (central) chamber of the plug rod. The gas supply connection means may have direct permeability, such as, for example, leading out through one / multiple different holes or one / multiple pipes of the rod-shaped plug body. Alternatively, the gas supply connection means may also have indirect permeability, such as, for example, a porous insert in the form of a rotationally symmetrical insert, for example, a cylindrical insert. The gas supply connection means may also be a mixture of direct and indirect permeability. Each gas supply connection means in the gas supply connection means may include a plurality of direct permeability elements, such as a plurality of different holes or pipes, preferably, the direct permeability element having a maximum dimension (such as a radius or a width) in the region where the direct permeability element leads out into the respective channel, the maximum dimension being lower than 0.2 mm, preferably lower than 0.1 mm.

[0029] Because the at least one channel is at least partially located on the outer surface of the nose, gas can be introduced into the molten metal at or near the nose. Because the at least one channel extends at least partially around the central longitudinal axis (L) and advances in the direction of the longitudinal axis (L), the inventors observed that the gas is initially accelerated in the channel to a deflected direction relative to the central longitudinal axis (L) of the stopper rod. When the gas leaves the at least one channel and enters the molten metal, this deflected gas entry causes a swirling flow of the molten metal near and below the nose.

[0030] In the outward direction of the at least one channel, i.e. on the side of the at least one channel facing away from the plug body, the at least one channel is preferably completely open. This has the advantage that the gas in the at least one channel already causes a rotational movement of the molten metal along the entire length of the at least one channel.

[0031] The at least one channel may be delimited by a wall (preferably, in addition to on the side of the channel facing away from the plug body, optionally, a segment of the channel may also be partially delimited on the side facing away from the plug body). This has the advantage that the gas can be guided and directed in a specific direction because the gas will be guided by the wall. The at least one channel preferably comprises a first channel wall, which limits the channel in a direction towards the first end, and may preferably comprise a second channel wall, which limits the channel in a direction towards the second end. The at least one channel preferably comprises a first channel wall, which limits the channel in a direction towards the first end, and may not comprise a second channel wall which limits the channel in a direction towards the second end. This allows the gas to be guided and directed in a specific direction (as defined by the first / upper wall) and further causes the gas to enter the molten metal in a more uniform manner. Therefore, according to a preferred embodiment, it is provided that each channel in the at least one channel comprises a first channel wall, the first channel wall limiting the channel in the direction towards the first end, wherein the first channel wall and the external surface of the nose form a first edge, and wherein the first edge has the shape of a sharp edge, preferably, the first edge has a radius of not more than 2mm, preferably not more than 1mm. Since more gas is retained in the channel, this further improves the gas guidance and directing to a specific direction. The at least one channel may include a channel bottom, which may be aligned with the first channel wall, and the channel bottom may be a linear region, or a curved region or line. The channel cross section may have different geometric forms, such as preferably a V-shaped cross section or a U-shaped cross section. Preferably, each gas supply connection device in the gas supply connection device leads into each channel in the at least one channel at the bottom of the channel.

[0032] Preferably, the at least one channel (each of the channels) defines a channel direction, wherein the channel direction (each of the channel directions) forms an angle (α) with the central longitudinal axis (L). i ) is aligned. Angle (α i ) is defined as the smaller angle between the channel direction and the central longitudinal axis (L) and, in the case of an oblique line, is defined as the smaller angle between any two intersecting lines parallel to the channel direction and the central longitudinal axis (L).

[0033] Preferably, the angle (each angle) (α i) is in the range between 30° and 60°, preferably in the range between 40° and 50°. The inventors have realized that this range allows to induce a swirl flow in a stable manner, e.g. with little fluctuation. Outside these ranges, the induced swirl flow is drastically reduced. Preferably, all angles (α i ) are the same, which produces a uniform flow of the molten metal. Preferably, all of the channels in the plurality of channels are aligned so that they induce the swirling flow into the same swirling flow direction. The induced swirling flow direction can be clockwise or counterclockwise, as seen along the central longitudinal axis (L) from the first end to the second end.

[0034] It is preferred to use a stopper rod according to the invention, the stopper rod comprising the at least one channel, and the at least one channel (each of the channels) causes a swirl flow into a swirl flow direction, and preferably, the swirl flow direction is clockwise or counterclockwise, as seen along the central longitudinal axis (L) from the first end to the second end. Preferably, the clockwise direction is used for applications deployed in the northern hemisphere, and the counterclockwise direction is used for applications deployed in the southern hemisphere.

[0035] Preferably, the at least one channel (each of the channels) extends along a spiral or swirling path on the outer surface of the nose. This has been shown to achieve optimal acceleration of the gas guided within the channel and has improved the swirling flow of the molten metal.

[0036] In the region of the first end, which forms the upper end of the plug body in the functional position of the plug rod, i.e. the central longitudinal axis is vertically aligned, means can be provided on the plug body, by means of which the plug body can be attached to a device for vertically lifting and lowering the plug rod. These means can be designed according to the prior art. For example, a fastener with an internal thread can be provided, into which a metal rod with an external thread can be screwed. The metal rod can then interact with the lifting device in such a way that the plug rod can be lifted and lowered via the metal rod.

[0037] In the region of its second end, which is opposite the first end and is the lower end of the plug body in the functional position of the plug rod, the outer surface (i.e., the outer contour) of the plug body has the shape of a nose or plug nose, as is known from the prior art. Preferably, the outer surface of the nose is rotationally symmetrical about the longitudinal axis. Preferably, the plug nose is understood to be a shape similar to a circular cone or dome, while the rest of the plug body can have a cylindrical outer contour that is rotationally symmetrical about the central longitudinal axis L.

[0038] The outer surface of the nose preferably expands from the second end in the direction towards the first end. According to a preferred embodiment, the outer surface of the nose expands conically from the second end in the direction towards the first end, or is formed as a cone. According to a particularly preferred design, the outer surface of the nose is dome-shaped.

[0039] As is known from the prior art, the stopper rod comprises a chamber which extends along a central longitudinal axis from a first end towards the second end into the stopper body and terminates in the stopper body away from the second end. The chamber can preferably be rotationally symmetrical about the central longitudinal axis and, for example, have a cylindrical shape. The stopper rod according to the invention comprises a gas supply connection leading from the chamber through the rod-shaped stopper body into the at least one channel. Thus, a gas introduced into the chamber, in particular an inert gas such as argon or nitrogen, can pass through the gas supply connection into the at least one channel.

[0040] In order to supply the chamber with gas, the chamber can be connected to a gas supply system. The gas supply system can be arranged as known from the prior art to supply gas, in particular in the region of the first end of the plug body.

[0041] The gas supply connection is designed such that gas can pass from the chamber through the plug body into the at least one channel.

[0042] Preferably, the at least one channel (each of the channels) is designed so that the gas supplied to the at least one channel of the stopper rod by the gas supply system via the chamber through the gas supply connection device leaves the at least one channel and enters the molten metal at an oblique angle relative to the central longitudinal axis, so as to cause a rotational flow of the molten metal.

[0043] Generally, rotational flow may be induced into a clockwise or counterclockwise direction when viewed from the first end to the second end.

[0044] Usually, the swirling flow can be measured by the circulation C, which is measured in m 2 / s. The circulation C is defined as the velocity vector Local and contour (i.e., line segment ) is the line integral of the tangent component on the closed loop so that Preferably, the rotational flow Rot(t) is defined by the circulation flow (Rot(t)=C). Preferably, the target for the rotational flow is defined by the target for the circulation flow (Rot 0 =C 0 ). Preferably, the swirling flow is defined by a swirl number. Preferably, the target for the swirling flow is defined by a target for the swirl number.

[0045] A gas supply element (such as a gas supply connection or channel) may have direct permeability or indirect permeability, depending on its properties in terms of letting gas flow through the element. Direct permeable elements allow gas to flow through discrete conduits (such as, for example, holes or pipes), while indirect permeable elements allow gas to pass through a permeable structure, for example in the sense of a porous structure. For example, this porous structure or element may have a porosity known from porous gas plugs used for gas purging of molten metal in a ladle.

[0046] Preferably, the plug rod comprises an auxiliary gas supply connection device, which is led out from the chamber and passes through the rod-shaped plug body into an auxiliary channel, the auxiliary channel is arranged on the external surface of the nose, and the auxiliary channel is designed to introduce additional gas into the molten metal without increasing the vortex-induced flow. Preferably, the auxiliary channel is annular or otherwise rotationally symmetrical around the central longitudinal axis (L). Preferably, the auxiliary gas supply connection device has direct permeability. Preferably, the auxiliary channel is arranged on the external surface of the nose, away from the at least one channel in the direction toward the second end. In other words, the auxiliary channel is located below the at least one channel (as in the use position). This allows additional gas to be introduced into the molten metal without further increasing the vortex-induced flow caused by the at least one channel.

[0047] According to a particularly preferred embodiment, the auxiliary channel, in particular if it is an annular channel, is rotationally symmetric about the central longitudinal axis (L). This allows a shielding effect to be produced on the nose by the air curtain generated from the auxiliary channel around the nose.

[0048] Preferably, the at least one channel is a plurality of channels (i.e. at least two channels / more than one channel), each of the plurality of channels being arranged in a rotationally symmetrical arrangement relative to the central longitudinal axis (L) such that the distance between each closest adjacent channel is the same (each adjacent pair of channels in the plurality of channels is equally spaced). The rotationally symmetrical arrangement of the plurality of channels again improves the flow characteristics of the molten metal, but additionally also reduces the forces and vibrations of the stopper rod itself.

[0049] Preferably, the at least one channel (each of the channels) has a maximum depth of at least 3 mm, preferably 7 mm, more preferably 12 mm. Preferably, the at least one channel (each of the channels) has a maximum depth of at least 3 mm, preferably 7 mm, more preferably 12 mm along at least (any) 30%, preferably at least 50%, and more preferably at least 70% of its channel length. It has been found that at a depth of less than 3 mm, a large part of the gas introduced into the channel is flushed out and the induced swirling flow is greatly reduced, while at a depth of more than 3 mm and even at more than 7 mm and more than 12 mm, sufficient gas is retained and guided in the channel. Additionally, at more than 12 mm, it seems that a specific guidance of the molten metal is additionally achieved, thereby improving the swirling flow characteristics.

[0050] Particularly preferably, the at least one channel (each of the channels) extends from a first channel end to a second channel end, and the second channel end is closer to the second end of the plug body than the first channel end. The distance between the first channel end and the second channel end defines the channel length. Preferably, the at least one channel (each of the channels) has a channel length in the range of 30 mm to 200 mm, preferably in the range of 50 mm to 150 mm, which produces a good directional flow of gas. Preferably, the at least one channel (each of the channels) has the same channel length, which reduces turbulence in the metal flow and reduces plug vibration.

[0051] Preferably, the (each) gas supply connection leads into the (each) at least one channel at a position between 50 mm and 100 mm from the second end of the plug body. In other words, the gas enters the at least one channel in an area where the molten metal flow rate is high during casting. This ensures that the gas is effectively sucked downwards by the molten metal flow and improves the guidance of the molten metal and gas and thus increases the swirling flow of the molten metal.

[0052] Preferably, the gas supply connection device (each of the gas supply connection devices) leads into the at least one channel (each of the channels) by means of indirect permeability. In other words, the gas supply connection device (each of the gas supply connection devices) allows the gas to flow into the at least one channel (each of the channels) via a permeable structure. Due to the reduced blockage of the gas supply connection device, this allows the gas flow to be easily started. Preferably, the gas supply connection device leads into the at least one channel (each of the channels) by means of indirect permeability of the channel at least in the region of the distance between 50mm and 100mm from the second end of the plug body. Preferably, the gas supply connection device (each of the gas supply connection devices) leads into the at least one channel (each of the channels) at the bottom of the channel. This ensures that the gas is effectively sucked downward by the molten metal flow, and a good guide is achieved, in particular for the molten metal and the good guide length of the gas in the channel. According to one embodiment, the gas supply connection device may include or be entirely composed of a material based on indirect permeability, so it may be at least one porous element. The at least one porous element has porosity, thereby allowing the gas to pass through the at least one porous element from the chamber to the channel.

[0053] Preferably, the at least one channel (each of the channels) provided on the outer surface of the rod-shaped plug body and at least partially provided on the outer surface of the nose are aligned so that the at least one channel (each of the channels) is provided on the outer surface of the nose through at least 50% of its channel length, preferably through at least 70% of its channel length, more preferably through at least 90% of its channel length, most preferably through its entire channel length. The remainder of the channel may be aligned adjacent to the nose on the outer surface of the plug body. This allows for good force transfer between the gas and the molten metal and has been shown to induce swirling flow with high yields.

[0054] The rod-shaped plug body and the chamber extending in the plug body along the central longitudinal axis can be designed according to the prior art. In this regard, the rod-shaped plug body can preferably be made of a refractory material, in particular a ceramic refractory material. In particular, the rod-shaped plug body can be made of alumina (Al 2 O 3 ) and carbon (ie, so-called alumina-carbon material).

[0055] The inventive stopper rod can be manufactured using existing technologies for producing stopper rods. In this respect, the stopper rod can be produced in the form of a one-piece stopper. The stopper body is preferably produced by isostatic pressing as known from the prior art. In addition to isostatic pressing, the gas supply line can be produced by, for example, drilling. For example, the channel can be milled out of the surface of the nose.

[0056] An object of the present invention is to provide a vessel for holding molten metal, the vessel comprising a bottom, wherein an outlet for discharging molten metal from the vessel is provided at the bottom, and wherein the amount of molten metal flowing through the outlet is controlled by a stopper rod according to the invention. The vessel for holding molten metal is preferably a tundish, preferably a tundish for containing molten metal, even more preferably a tundish for containing molten steel, in particular in a continuous casting facility. The outlet is preferably a tundish nozzle.

[0057] An object of the present invention is the use of a stopper rod according to the present invention in a vessel for holding molten metal, preferably a tundish, preferably a tundish for receiving molten metal, even more preferably a tundish for containing molten steel, in particular in a continuous casting installation, for controlling the flow of molten metal through a nozzle, such as a tundish nozzle.

[0058] In a second aspect of the present invention, the object is achieved by providing a method for controlling the flow rate of molten metal and for inducing a swirling flow of the molten metal, the method comprising:

[0059] - a stopper rod setting step for setting a stopper rod according to the invention, for example, to a stopper rod control system with a lifting device for controlling the flow of molten metal, such as a stopper rod comprising:

[0060] Rod-shaped plug:

[0061] The rod-shaped plug body extends along a central longitudinal axis (L) from a first end to a second end, and the rod-shaped plug body includes a nose portion located at the second end.

[0062] in,

[0063] The nose provides an exterior surface;

[0064] A chamber which:

[0065] Extending within the plug body along the central longitudinal axis (L) from the first end toward the second end and terminating away from the second end;

[0066] At least one channel, preferably a plurality of channels:

[0067] is arranged on the outer surface of the rod-shaped plug body and at least partially on the outer surface of the nose, and at least partially around the central longitudinal axis (L)

[0068] Extending and advancing in the direction of the central longitudinal axis (L);

[0069] A gas supply connection connects the chamber and each of the at least one channel.

[0070] - a gas supply system setting step, in which the gas supply system provides gas to the chamber;

[0071] - a gas guiding step, in which the gas is guided by the gas supply system at a (eg predetermined) gas flow rate (Q(t)) via the chamber through the gas supply connection to the at least one channel of the stopper rod.

[0072] Preferably, the stopper rod is a stopper rod according to the present invention, more preferably, the stopper rod is a stopper rod according to the first aspect of the present invention.

[0073] Preferably, the stopper rod comprises an auxiliary gas supply connection device, which leads out from the chamber and passes through the rod-shaped stopper body into an auxiliary channel, and the auxiliary channel is arranged on the outer surface of the nose. Preferably, the auxiliary channel is annular. Preferably, the auxiliary channel has direct permeability, and the direct permeability is achieved by at least one of a hole and a pipe. The step of guiding the gas through the chamber through the gas supply connection device to the at least one channel of the stopper rod by the gas supply system, for example, at a predetermined gas flow rate, includes setting the gas pressure of the gas, for example, so that the predetermined gas flow rate is guided into the at least one channel.

[0074] Preferably, the method additionally comprises:

[0075] - a tundish nozzle setting step for setting a tundish nozzle and a cyclonic flow measuring unit capable of measuring a cyclonic flow (Rot(t)) of the molten metal in the tundish nozzle;

[0076] - a swirling flow determining step for determining the swirling flow (Rot(t)) of the molten metal in the tundish nozzle by the swirling flow measuring unit;

[0077] - a target setting step for setting a target (Rot0) of the rotational flow in the tundish nozzle;

[0078] - a gas increasing step for increasing the gas flow rate (Q(t)) when the target (Rot0) of the swirl flow is higher than the determined swirl flow (Rot(t));

[0079] - A gas reduction step for reducing the gas flow rate (Q(t)) if the target (Rot0) of the swirl flow is lower than the determined swirl flow (Rot(t)).

[0080] Preferably, the cyclonic flow measurement unit may be integrated into the tundish nozzle. Alternatively, the cyclonic flow measurement unit may be aligned with the tundish nozzle. The cyclonic flow measurement unit may include a coil that measures the magnetic field displacement generated by the cyclonic flow of the molten metal in the tundish nozzle. The cyclonic flow (Rot(t)) and the target of the cyclonic flow (Rot(t)) are 0 ) can be indicated by the swirl number. The swirling flow (Rot(t)) and the target of the swirling flow (Rot 0 ) can be represented by m 2 Circulation C indication in units of / s. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Exemplary embodiments of the invention are explained in more detail with the aid of the drawings.

[0082] Figure 1a is a cross-sectional view of a tundish comprising a stopper rod according to the invention, wherein an outlet in the form of an immersed nozzle is provided at the bottom of the tundish;

[0083] Figure 1b is a cross-sectional view of an alternative embodiment of a tundish comprising a stopper rod according to the invention, wherein an outlet in the form of an immersed inlet shroud is provided at the bottom of the tundish;

[0084] Figure 2 The left side is based on Figure 1a and Figure 1b A front view of the plug rod;

[0085] Figure 2 The right side is based on Figure 1a and Figure 1b A cross-sectional view of a plug rod;

[0086] Figure 3a is based on Figure 1a and Figure 1b a view of the nose of the stopper stem; and Figure 3b is more detailed Figure 3a Channel;

[0087] Figure 4 is a view of the nose of a plug rod according to a second embodiment of the present invention;

[0088] Figure 5 is a view of a nose of a plug rod according to a third embodiment of the present invention;

[0089] Figure 6 is a view of the nose of a plug rod according to a fourth embodiment of the present invention;

[0090] Figure 7 The results of the gas flow rate analysis with different time steps are shown. Figure 1a and Figure 1b Results of CFD simulation of the plug rod;

[0091] Figure 8 The results are shown for the case without gas flow at different time steps. Figure 1a and Figure 1b Results of CFD simulation of the plug rod;

[0092] Fig. 9 A graph depicting the variation of the gas flow rate Q and the induced annular flow C as a function of the gas pressure p is shown;

[0093] Fig.10 A diagram showing a method of steps according to an embodiment of the present invention.

[0094] In order to better illustrate the features of the embodiments shown in the drawings, the drawings do not reflect the scale of the embodiments according to customary practice. DETAILED DESCRIPTION

[0095] Figure 1a A tundish, which is designated in its entirety by reference numeral 1, is shown, which is part of a continuous casting installation for casting steel. As is known from the prior art, the tundish 1 comprises a metal container 3 lined therein with a refractory material 5. Molten metal can be provided in a space enclosed by the refractory material 5. In the bottom 7 of the tundish 1, a tundish nozzle 9 in the form of an immersion nozzle (SEN) is provided, through which the molten metal in the tundish 1 can be cast into a mould (not shown). A vertically aligned central longitudinal axis L of a stopper rod 100 extends through the tundish nozzle 9.

[0096] Along the central longitudinal axis L, the plug rod 100 is arranged in its functional position. The plug rod 100 is connected to a prior art lifting device (not shown), by means of which the plug rod 100 can be lifted and lowered along the central longitudinal axis L. The plug rod 100 comprises a plug body 101, which comprises a plug nose 103 at its second end / lower end. By means of the lifting device, the plug rod 100 can be lifted to Figure 1a In the second position shown in FIG. 1 , the tundish nozzle 9 is opened so that the molten metal provided in the tundish 1 can be cast through the tundish nozzle 9 (here, an immersion nozzle 9). In addition, the stopper rod 100 can be lowered to the first position ( Figure 1a In this position, the plug nose 103 abuts against the tundish nozzle 9, so that the tundish nozzle is closed by the plug rod 100. Therefore, the tundish nozzle 9 can be closed and opened by means of the plug rod 100, thereby controlling the amount of molten metal flowing through the tundish nozzle 9. A gas supply system 210 for providing gas 200 to the plug rod 100 is also shown.

[0097] According to Figure 1aThe intermediate package 1 and according to Figure 1b The same as the middle package 1, Figure 1b The tundish 1 shown in FIG. Figure 1a The tundish shown in FIG. 1 is the same as that shown in FIG. 2 , except that the gas supply system 210 for providing the gas 200 is not shown. Figure 1a and Figure 1b The difference between the intermediate package 1 is that: Figure 1b A tundish nozzle 10 in the form of a submerged inlet shroud (SES) is provided in the bottom 7 of the tundish 1. As known from the prior art, the submerged inlet shroud 10 comprises an upper portion 10.1 located at the bottom 7 of the tundish 1 and a lower portion 10.2 attached below the upper portion 10.1, such that the upper portion 10.1 and the lower portion 10.2 form a continuous chamber along the central longitudinal axis of the submerged inlet shroud 10.

[0098] Figure 2 A first embodiment of the plug rod 100 shown in FIG. 1 is shown in a front view (left side) and in a cross-sectional view (right side). The plug rod 100 comprises a rod-shaped plug body 101, the outer circumferential surface of which is rotationally symmetrical with respect to the central longitudinal axis L of the plug rod 100. The plug body 101 extends along the central longitudinal axis L from its first upper end 105 in the functional position according to FIG. 1 to its second lower end 107 in the functional position according to FIG. 1. At its second end 107, the plug body 101 comprises a nose 103. The second nose end 104b of the nose 103 is aligned with the second end 107 of the plug body 100. The outer surface of the plug body 101 in the region between the first end 107 of the plug body 100 up to the first nose end 104a has a cylindrical outer contour which is rotationally symmetrical with respect to the central longitudinal axis L. The outer surface of the nose 103 between the first nose end 104a and the second nose end 104b is rotationally symmetrical with respect to the longitudinal axis L and is generally dome-shaped.

[0099] like Figure 2 As shown (right side), the plug body 101 has a chamber 109 which extends into the plug body 101 from the first end 105 along the central longitudinal axis L in the direction towards the second end 107 and terminates in the plug body 101 away from the second end 107. The chamber 109 is rotationally symmetric about the central longitudinal axis and has a cylindrical shape along most of its height.

[0100] The plug body 101 is preferably made of alumina-carbon material (Al 2 O 3 The plug body 101 can be produced as a monolithic plug body by means of isostatic pressing.

[0101] The gas supply system 200 provides a gas 210 to the stopper rod 100 at the first end 105, through which the gas 210 (such as an inert gas, such as argon or nitrogen) is led into the chamber 109. From the chamber 109, the gas is further led to the channel 111 via the gas supply line 123. In the channel 111, the gas 210 is accelerated along the channel direction 112 and finally leaves the channel 111 into the molten metal and applies a swirling flow to the molten metal.

[0102] In this embodiment, six channels 111 are arranged on the outer surface of the nose 103. All channels 111 follow a spiral path around the central longitudinal axis L, that is, they extend at least partially around the central longitudinal axis (L) (see Figure 3a ), and proceeds in the direction (z) of the central longitudinal axis (L); the channel 111 is completely open to the outside, i.e. on the side of the channel 111 facing away from the plug body 101, and is limited by a first channel wall 113 and a second channel wall 115 according to its V-shaped cross-sectional area, which start from a common linear area forming a channel bottom 117 of the channel 111 (see Figure 3b ). Towards the outer surface of the nose 103, the first channel wall 113 and the second channel wall 115 diverge and eventually merge into the outer surface of the nose 103. The first channel wall 113 limits the channel 111 in the direction toward the first end 105 and forms a first edge 119 with the outer surface of the nose 103. The second channel wall 115 limits the channel 111 in the direction toward the second end 107 and forms a second edge 121 with the outer surface of the nose 103. The first edge 119 and the second edge 121 each form a sharp edge with a radius much smaller than 0.5 mm. The first edge 119 and the second edge 121 extend equidistantly from each other around the longitudinal axis L and advance in the direction of the central longitudinal axis, similar to the spiral path of the channel 111 on the outer surface of the nose 103. The distance between the first edge 119 and the second edge 121 defines the width of the channel mouth, i.e., the width of the channel 111 in the region where the channel 111 merges into the outer surface of the nose 103, and is 10 mm in this embodiment. The shortest distance between an imaginary plane extending between the first edge 119 and the second edge 121 and the channel bottom 117 defines the depth of the channel 111, which in this embodiment is 8 mm. This yields 40 mm 2 The cross-sectional area of ​​the channel 111 is .

[0103] Each channel 111 defines a channel direction 112 and each of the six channel directions 112 is at an angle (α) to the central longitudinal axis (L). i ). The angle (α i) is defined as the smaller angle between the channel direction and the central longitudinal axis (L), and in the case of an oblique line, is defined as the smaller angle between any two lines parallel to the channel direction and the central longitudinal axis (L). Here, all angles (α i ) are the same, where for all i=1...6, α i =45°.

[0104] From the chamber 109, a gas supply connection 123 is led through the refractory material of the plug body 101 into the corresponding channel 111 in the form of one gas supply line 123 per channel 111. The six gas supply lines 123 each have a straight course with a circular cross-sectional area and are arranged symmetrically with respect to the central longitudinal axis L and are evenly spaced from each other. Therefore, the six gas supply lines 123 are spaced from each other by a rotation angle of 60° with respect to the central longitudinal axis L. (i.e., relative to the central longitudinal axis L 60°, 120°, 180°, 240°, 300°). According to their symmetry with respect to the central longitudinal axis L, the gas supply line 123 leads into the six channels 111 at six evenly spaced areas, which are also rotated at an angle of 60° with respect to the central longitudinal axis L. (i.e., relative to the central longitudinal axis L ) are separated from each other, as in Figure 3a As can be seen particularly clearly in FIG. 1 , which is a view from the plug nose 103 / second end 107 of the plug body (i.e., from below the plug rod 100 in its use position). Therefore, the distance between each of the closest adjacent channels 111 is the same (each adjacent pair of channels in the plurality of channels 111 is equally spaced).

[0105] The gas supply lines 123 each extend along a corresponding longitudinal axis, wherein the six longitudinal axes of the gas supply lines 123 intersect at a common point on the central longitudinal axis L. The six longitudinal axes of the gas supply lines 123 are each arranged to form an angle of approximately 60° with the central longitudinal axis L of the plug body 101, which is a smaller angle sandwiched between a segment where the longitudinal axis of the gas supply line 123 passes through the gas supply line 123 and a segment where the central longitudinal axis L of the plug body 101 passes through the second end 107 of the plug body 101.

[0106] like Figure 3a and Figure 3b As shown, the gas supply line 123 leads by means of direct permeability into each of the corresponding six channels 111. In other words, the gas supply line 123 allows gas to flow into each of the corresponding six channels 111 via a separate conduit.

[0107] Each channel in the channel 111 extends from a first channel end 111u to a second channel end 111d, and each second channel end 111d is closer to the second end 107 than the corresponding first channel end 111u. The distance between the corresponding first channel end 111u and the second channel end 111d defines a channel length 111l. In this embodiment, all channel lengths 111l are the same, i.e. 160mm (alternatively, as shown in the figure, all channel lengths 111l are the same, i.e. 50mm, and each second channel end 111d is arranged at a distance of 50mm from the second end 107 of the plug body). Each gas supply line 123 leads to one of the six channels 111 at a position in the channel at a distance of 80mm from the second end 107 of the plug body.

[0108] An alternative first embodiment (not shown in the drawings) differs from the first embodiment mentioned above in that there is no second channel wall 115 limiting the channel 111 in the direction towards its second end 107, and therefore no second edge 121. Here, the channel diverges continuously and smoothly into the surface of the nose 103 in the direction towards its second end 107.

[0109] Figure 4 The second embodiment of the invention shows a stopper rod 100 with an auxiliary gas supply connection 133, which is an auxiliary gas supply line here, which leads from the chamber 109 through the rod-shaped stopper body 101 into an auxiliary channel 131 with an annular geometry, which is aligned on the outer surface of the nose 103. The auxiliary channel 131 is arranged on the outer surface of the nose 103 away from the channel 111 in the direction towards the second end 107 (below the channel 111 in the use position). The auxiliary gas supply connection 133 (which is an auxiliary gas supply line here) is connected by means of the auxiliary gas supply connection 133 as shown in FIG. Figure 4 The direct permeability shown leads into the annular auxiliary channel 131. In other words, the auxiliary gas supply connection 133 (which is an auxiliary gas supply line here) allows gas to flow into the auxiliary channel 131 via a discrete conduit. The annular auxiliary channel 131 is symmetrical about the central longitudinal axis (L), that is, the central longitudinal axis passes through the center of the annular auxiliary channel 131. In this embodiment, the radius of the auxiliary channel is 15 mm and the slit of the annular auxiliary channel has a width of 0.5 mm.

[0110] Figure 5The third embodiment of the plug rod 100 is similar to the first or second embodiment, except that six gas supply lines 123 are led into the six channels 111 by means of indirect permeability. In other words, the gas supply lines 123 allow gas to flow into each of the corresponding six channels 111 via the permeable structure. Here, the indirect permeability / porous structure spans an area at a distance of between 50 mm and 100 mm from the second end 107 of the plug body, wherein the gas supply line 123 is led into the channel 111 at the bottom 117 of the channel 111.

[0111] Figure 6 The fourth implementation is similar to Figure 5 The third embodiment, except that the indirect permeable / porous structure spans through the entire channel length 1111 from the first channel end 111u to the second channel end 111d.

[0112] In another embodiment, a stopper rod (100) according to one of the first, second, third, fourth or fifth embodiments is provided, the gas supply system 200 supplies gas 210 to the chamber 101 at a gas flow rate of 5 l / min, the gas is argon gas, and the gas is guided to the six channels 111 through the gas supply line 123 via the chamber 109 at the predetermined gas flow rate. In the channel 111, the gas 210 is accelerated along the channel direction 112 and finally leaves the channel 111 into the molten metal and applies a swirling flow to the molten metal.

[0113] For the stopper rod 100 according to the first embodiment, a computer-based numerical simulation based on the CFD (Computational Fluid Dynamics) method was performed in both cases with and without injection of the gas 210 .

[0114] Figure 7 and Figure 8 The results are shown. Figure 7 The left image of shows the metal flow and the flow characteristics shortly after the start of gas injection (here at t=0.1 s after the start of gas injection). The flow lines (shown as black lines) within the tundish nozzle 9 show the start of the swirling flow. Annular flow (determined at the height indicated by the ellipse) C=0.063 m 2 / s. The right image shows the situation at t=11s, where a strong swirling flow of the molten metal is observed in the tundish nozzle 9 (see the spiral path of the flow lines shown as black lines in the tundish nozzle 9). At t=11s (at the height of the ellipse), the annular flow C=0.298m 2 / s.

[0115] exist Figure 8In FIG. 1 , the results for the case without injection of gas 210 can be seen. Here, during the entire simulation, a low rotational flow is experienced in the tundish nozzle 9 (at t=10 s, as shown in FIG. 1 ). Figure 8 As shown on the left, the swirling flow is very low, and the circulation C = 0.018m 2 / s, at t = 21s, if Figure 8 As shown on the right, the swirling flow is still very low, with circulation C = 0.022m 2 / s). In addition, the simulations show that the flow is more unstable without the injection of argon.

[0116] The results show that the stopper rod 100 of the embodiment is suitable for inducing a swirling flow into a molten metal by injecting a gas into the channel 111 .

[0117] Fig. 9 The result achieved by the stopper rod according to the third embodiment is schematically shown in the upper diagram: a diagram showing the gas flow Q (in l / min) of the gas 210 as a function of the pressure (in bar). thres , basically no gas flow Q is observed (Q≈0). Above the threshold pressure p thres , the gas flow rate Q gradually increases, and all the gas 210 is delivered to the annular auxiliary channel 131 through the auxiliary gas supply connection device 133 (which is the auxiliary gas supply line here). This is because the flow resistance of the six channels 111 of indirect permeability is higher than the flow resistance of the annular auxiliary channel 131 of direct permeability. In this flow state, substantially no or very low rotational flow is induced into the molten metal (Rot(t)=C is very small). Only above the saturation pressure p sat , the gas 210 starts to flow into the six gas supply lines 123 and the six channels 111. By further increasing the pressure, more and more gas 210 is injected into the molten metal through the six channels 111, thereby increasing the rotational flow (Rot(t)=C increases in this state). Fig. 9 The following figure schematically shows that the induced rotational flow Rot (in this embodiment, in the form of a ring flow, Rot (t) = C, the unit is m 2 / s) is shown as a function of pressure (in bar). Thus, by directing gas 210 by the gas supply system 200 via the chamber 109 through the gas supply connection 123 to the six channels 111 of the stopper rod at a (e.g., predetermined) gas flow rate, a specific swirl flow can be induced into the molten metal.

[0118] In order to set a specific swirl flow of the molten metal, an additional swirl flow measuring unit 20 can be used. This makes it possible to increase the gas flow rate if a higher swirl flow of the molten metal is required, or to reduce the gas flow rate if a lower swirl flow of the molten metal is required. Thus, active control of the induced swirl flow (using feedback) can be achieved. This is particularly useful in Fig.10 , wherein a stopper rod 100 according to the present invention is set in a stopper rod setting step 300, a gas supply system 200 is set in a gas supply system setting step 310, and a tundish nozzle 9, 10 including a swirl flow measurement unit 20 is set in a tundish nozzle setting step 320. The gas 210 is guided by the supply system 200 to the channel 111 of the stopper rod 100 via the chamber 109 through the gas supply connection device 123 at a (e.g., predetermined) gas flow rate (Q(t) at a specific time t) in a gas guiding step 325. In a swirl flow determining step 330, the swirl flow (Rot(t) at time t, in this embodiment, the swirl flow is characterized by a circular flow Rot(t)=C) of the molten metal in the tundish nozzles 9, 10 is determined by the swirl flow measurement unit 20. In a target setting step 340, a specific target (Rot(t)) of the swirl flow is set in the tundish nozzles 9, 10. 0 =C 0 ). In the case of a rotating flow target (Rot 0 =C 0 ) is higher than the determined rotational flow (Rot(t) = C), that is, Rot 0 > Rot(t), in the gas increase step 350, the gas flow rate (Q(t)) is increased, for example, by a specific amount ΔQ, so that Q(t+1)=Q(t)+ΔQ, which causes an increase in the rotational flow (Rot(t)=C). At the target of the rotational flow (Rot 0 =C 0 ) is lower than the determined rotational flow (Rot(t) = C), that is, Rot 0 < Rot(t), in the gas reduction step 360, the gas flow rate (Q(t)) is reduced, for example by a certain amount ΔQ, so that Q(t+1)=Q(t)-ΔQ, which causes a reduction in the rotational flow (Rot(t)=C). This allows achieving and maintaining the rotational flow (Rot(t)=C) at or at least close to the rotational flow (Rot 0 =C 0 ), so Rot(t)=C=Rot 0 =C 0 .

[0119] List of reference symbols and coefficients:

[0120] L passes through the central longitudinal axis of the plug body

[0121] r is the radial distance from L (normal distance)

[0122] z is the z-axis along the direction of L in the direction from the first end of the plug body to the second end of the plug body,

[0123] Rotation angle around L

[0124] α i The angle between the i-th channel direction and the z-axis

[0125] Q(t) is the gas flow rate at time t

[0126] Rot(t) is the rotational flow determined at time t

[0127] Rot 0 Target of swirling flow

[0128] C in m 2 Circulation in units of / s

[0129] C 0 For m 2 The target of the circulation in / s

[0130] 1 Tundish

[0131] 3 Metal containers

[0132] 5 Refractory materials

[0133] 7 Bottom of the tundish

[0134] 9 Tundish nozzle in the form of submerged nozzle (SEN)

[0135] 10 Tundish nozzle in the form of submerged entry shroud (SES)

[0136] 10.1 Upper part of the immersion inlet shield (SES)

[0137] 10.2 Lower part of the immersion inlet shield (SES)

[0138] 20 Rotational flow measurement unit

[0139] 100 Plug rod

[0140] 101 Plug

[0141] 103 Nose of plug

[0142] 104a First nose end

[0143] 104b Second nose end

[0144] 105 First end of plug body

[0145] 107 Second end of plug body

[0146] 109 Chamber

[0147] 111 channels

[0148] 111u First channel end

[0149] 111d Second channel end

[0150] 111l Channel length

[0151] 112 Channel Direction

[0152] 113 First channel wall

[0153] 115 Second channel wall

[0154] 117 Channel Bottom

[0155] 119 First Edge

[0156] 121 The Second Edge

[0157] 123 Gas supply connection

[0158] 131 Auxiliary Channels

[0159] 133 Auxiliary gas supply connection

[0160] 200 Gas supply system

[0161] 210 Gas

[0162] 300 Plug Rod Setting Procedure

[0163] 310 Gas Supply System Setup Steps

[0164] 320 Tundish Nozzle Setting Steps

[0165] 325 Gas Pilot Steps

[0166] 330 Rotational Flow Determination Steps

[0167] 340 Goal Setting Steps

[0168] 350 Gas Increase Steps

[0169] 360 Gas reduction steps.

Claims

1. A stopper rod (100) for controlling the flow of molten metal and for inducing a swirling flow of the molten metal, the stopper rod (100) comprising: 1.

1. Rod-shaped plug body (101): 1.1.

1. The rod-shaped plug body (101) extends along a central longitudinal axis (L) from a first end (105) to a second end (107), 1.1.

2. The rod-shaped plug body (101) comprises a nose portion (103) located at the second end (107), wherein: 1.1.

3. The nose (103) provides an external surface; 1.

2. Chamber (109), the chamber (109): 1.2.

1. extending from the first end (105) toward the second end (107) within the plug body (101) along the central longitudinal axis (L) and terminating away from the second end (107); 1.

3. At least one channel (111), preferably a plurality of channels (111): 1.3.

1. The at least one channel (111) is provided on the outer surface of the rod-shaped plug body (101), 1.3.

2. Furthermore, the at least one channel (111) is at least partially disposed on the outer surface of the nose (103), 1.3.

3. Furthermore, the at least one channel (111) extends at least partially around the central longitudinal axis (L), 1.3.

4. Furthermore, the at least one channel (111) advances in the direction of the central longitudinal axis (L); 1.

4. Gas supply connection device (123), the gas supply connection device (123): 1.4.

1. Connecting the chamber (109) and each of the at least one channel (111).

2. The stopper rod (100) according to claim 1, wherein: The at least one channel (111) comprises a first channel wall (113) limiting each channel of the at least one channel (111) in a direction toward the first end (105), wherein the first channel wall (113) and the outer surface of the nose (103) form a first edge (119), and wherein the first edge (119) has the shape of a sharp edge, the first edge (119) having a radius not greater than 2 mm, preferably not greater than 1 mm.

3. The stopper rod (100) according to at least one of the preceding claims, wherein Each of the at least one channel (111) defines a channel direction (112), and wherein each of the channel directions (112) is at an angle (α) to the central longitudinal axis (L). i ) are aligned, and wherein the angle (α i ) is in the range of 30° to 60°, preferably in the range of 40° to 50°.

4. The stopper rod (100) according to at least one of the preceding claims, wherein Each of the at least one channel (111) defines a channel direction (112), and wherein each of the channel directions (112) is at an angle (α) to the central longitudinal axis (L). i ) are aligned, and wherein the angle (α i ) are the same for all angles.

5. The stopper rod (100) according to at least one of the preceding claims, wherein Each of the at least one channel (111) extends along a spiral path on the outer surface of the nose (103).

6. The stopper rod (100) according to at least one of the preceding claims, wherein The stopper rod (100) comprises an auxiliary gas supply connection device (133), which is led out from the chamber (109) and passes through the rod-shaped stopper body (101) into an auxiliary channel (131), and the auxiliary channel (131) is arranged on the outer surface of the nose (103), preferably the auxiliary channel (131) is annular, and preferably the auxiliary channel (131) has direct permeability, and the direct permeability is achieved by at least one selected from the group consisting of: holes and pipes.

7. The stopper rod (100) according to at least one of the preceding claims, wherein Each of the gas supply connections (123) leads into each of the at least one channel (111) by means of indirect permeability, which is achieved by at least one porous insert.

8. The stopper rod (100) according to at least one of the preceding claims, wherein The at least one channel (111) is a plurality of channels (111), each channel (111) of the plurality of channels (111) being arranged in a rotationally symmetrical arrangement relative to the central longitudinal axis (L) such that the distance between each closest adjacent channel (111) is the same.

9. The stopper rod (100) according to at least one of the preceding claims, wherein Each of the at least one channel (111) has a maximum depth of at least 3 mm, preferably 7 mm, more preferably 12 mm.

10. The stopper rod (100) according to at least one of the preceding claims, wherein Each channel of the at least one channel (111) extends from a first channel end (111u) to a second channel end (111d), and the second channel end (111d) is closer to the second end (107) than the first channel end (111u).

11. The stopper rod (100) according to at least one of the preceding claims, wherein Each of the at least one channel (111) extends from a first channel end (111u) to a second channel end (111d), and the second channel end (111d) is closer to the second end (107) than the first channel end (111u), wherein the distance between the first channel end (111u) and the second channel end (111d) defines a channel length (111l), wherein each of the at least one channel (111) has a maximum depth of at least 3 mm, preferably 7 mm, and more preferably 12 mm along at least 30%, preferably at least 50%, and more preferably at least 70% of the channel length (111l).

12. The stopper rod (100) according to at least one of the preceding claims, wherein The gas supply connection (123) leads into each of the at least one channel (111) at a position between 50 mm and 100 mm from the second end (107) of the plug body (101).

13. The stopper rod (100) according to at least one of the preceding claims, wherein The plug body (101) is made of refractory ceramic material.

14. A method for controlling the flow rate of molten metal and for inducing a swirling flow of the molten metal, the method The following steps are involved: 14.

1. A stopper rod setting step (300), in which a stopper rod (100) is set. The stopper rod (100) include: 14.1.

1. Rod-shaped plug body (101): 14.1.1.

1. The rod-shaped plug body (101) extends along a central longitudinal axis (L) from a first end (105) to a second end (107), 14.1.1.

2. The rod-shaped plug body (101) comprises a nose portion (103) located at the second end (107), in, 14.1.1.

3. The nose (103) provides an external surface; 14.1.

2. Chamber (109), the chamber (109): 14.1.2.

1. extending into the plug body (101) along the central longitudinal axis (L) from the first end (105) towards the second end (107), and terminates away from said second end (107); 14.1.

3. At least one channel (111), preferably a plurality of channels (111): 14.1.3.

1. is disposed on the outer surface of the rod-shaped plug body (102) and at least partially on the outer surface of the nose (103), and 14.1.3.

2. extending at least partially around said central longitudinal axis (L), 14.1.3.

3. and moving in the direction of said central longitudinal axis (L); 14.1.

4. Gas supply connection device (123), the gas supply connection device (123): 14.1.4.

1. Connecting the chamber (109) and each of the at least one channel (111); 14.

2. A gas supply system setting step (310), in which the gas supply system (200) provides gas (210) to the chamber (109); 14.

3. A gas guiding step (325), in which the gas (210) is guided by the gas supply system (200) at a gas flow rate (Q(t)) via the chamber (109) through the gas supply connection device (123) to the at least one channel (111) of the stopper rod (100).

15. The method according to claim 14, comprising the following additional steps: 15.

1. A tundish nozzle setting step (320), in which a tundish nozzle (9, 10) is set, wherein the tundish nozzle (9, 10) includes a swirling flow measuring unit (20) capable of measuring the swirling flow (Rot(t)) of the molten metal in the tundish nozzle (9, 10); 15.

2. A rotational flow determination step (330), in which the rotational flow (Rot(t)) of the molten metal in the tundish nozzle (9, 10) is determined by the rotational flow measurement unit (20); 15.

3. A target setting step (340), in which a target (Rot0) of the rotational flow in the tundish nozzle (9, 10) is set; 15.

4. A gas increasing step (350), in which the gas flow rate (Q(t)) is increased when the target (Rot0) of the swirl flow is higher than the determined swirl flow (Rot(t)); 15.

5. A gas reduction step (360) in which the gas flow rate (Q(t)) is reduced when the target (Rot0) of the swirl flow is lower than the determined swirl flow (Rot(t)).

Images