EP0290523B2 - Discharge and flow regulator for metallurgical vessels and casting process - Google Patents

Abstract

A stopper (6) secured to the lower end of a stopper rod has a faucet (13) with a radial throttle opening (14). A conoidal shut-off face (16) is provided in the stopper (6), above the throttle opening (14). The annular surface of the stopper (13), which penetrates into the outlet bore, provides an additional seal. The stopper (6) can be turned, thus influencing the direction of flow of the outflowing molten mass. The flow can thus be regulated and a high shut-off safety is obtained. Turbulences in the molten mass are further avoided, thus preventing slag from being entrained.

Description

The invention relates to an outlet and flow control device for a metallurgical melt-receiving vessel, which has an outlet pipe located on the bottom of the vessel with a pouring opening, with a stopper which cooperates with the outlet pipe, the stopper in its closed position inserting one into the bore of the Exhaust pipe protruding, at least approximately cylindrical, serving as shut-off device, which contains at least one radial throttle opening on its circumference, which merges into a longitudinal channel of the pin open at the bottom and between the plug and the outlet pipe above the throttle opening there is a first seal that can be closed by lowering the plug.

Furthermore, the invention relates to a casting method for pouring molten metal from a metallurgical vessel, which contains at least one outlet opening located on the bottom of the vessel, which cooperates with a stopper to form sealing elements, the melt in the opened stopper position via an at least approximately horizontal outlet opening in the Plug and its longitudinal channel open at the bottom flows out.

Numerous devices are already known for the outlet and the flow control of metallic melts from a vessel.

In a well-known system for casting crude steel or the like. a stopper device is used in which the outlet opening in the bottom of the vessel can be closed by a stopper in the inside of the vessel, which is fastened to the lower end of a rod. The plug can be raised for casting and lowered for closing the spout by means of a lever linkage that can be operated from the outside. Disadvantages are, however, the poor control characteristics of the flow and an unsatisfactory security against closure, for example if there are lugs on the stopper.

It has also been proposed to use dome-type rotary valves in which an eccentric inlet channel can be brought into communicating connection with an outlet opening by means of a rotary connection. This requires high processing and grinding accuracy of the difficult to manufacture spherical separation point between rotating and stationary components. In addition, with such a construction, the melt tends to freeze in the pouring opening.

Slider closures are also known attached to the vessel containing the melt. In such slide closures, the closure bodies sliding on one another under pretension are subject to considerable wear, since the movement of the adjustable part must take place under the influence of the high temperature of the molten metal. Another disadvantage is the high purchase and Maintenance costs. In order to ensure sufficient security of the seal, high machining accuracy of the slide plates made of refractory material is required.

From FR-A 2 315 347 a device for regulating the outlet of melts is known, in which there is a stopper which can be actuated by a linkage from below. The plug head is provided with a sealing surface, which forms a seal together with an annular perforated brick. The stopper is provided directly adjacent to the sealing surface with a plurality of radial openings which open into a central outlet channel which is open at the bottom. The weakening of the plug cross-section directly below the head, which is at risk of breakage, is unsatisfactory, since the refractory materials used have a high compressive strength but only a low tensile strength and tensile stress occurs here to generate the closing force. The security of the closure is also unsatisfactory because of the risk of build-up or erosion in the closure area. If the seal fails, a melt breakthrough has catastrophic consequences. The risk of slag entrainment cannot be eliminated with this closure device, since, together with the trough-shaped depression in the perforated brick, an oblique or even essentially vertical flow forms in the melt. There is also a risk of freezing when pouring on, since the melt cools rapidly in the trough which is wedge-shaped in cross section. Since the joint between the movable plug and the stationary perforated brick is connected to ambient air at the bottom, air can be sucked in by the vacuum created during casting, which causes undesired reoxidation of the melt.

DE-A 1 558 285 shows a piston lock for ladles. The reciprocating piston is provided with drive means which engage at the bottom and with which a pure axial displacement into the opening and closing position can be effected. A radial opening opens into a central flow opening that is open at the bottom. Since a widened head is missing on the reciprocating piston, the seal is limited to the part located above the radial opening of the reciprocating piston together with the perforated brick hole. The perforated stone sits in a funnel-shaped recess in the bottom of the pan, which is why no predominantly horizontal direction of flow is formed during pouring, but the suction of the flowing melt will propagate in the upward direction and, as a result, parts of the slag can be entrained.

The object to be achieved with the invention is to create an outlet and flow control device and a casting method which has a simple, inexpensive to manufacture structure, allows a constant, precise control of the flow of melt, and results in a high level of sealing reliability and at The casting process largely avoids the formation of eddies and prevents slag running along the outflowing melt, while maintaining good flow controllability and tightness.

The device according to the invention with which this object is achieved is characterized in that the stopper is located at the lower end of a vertically movable rod protruding from above into the interior of the vessel, the rod is articulated and has radial play with respect to the stopper neck surrounding it, and the pin between its radial throttle opening and the sealing surface located above it contains a ring part closed on the casing, which together with the adjacent part of the bore forms a second seal.

The casting method according to the invention is characterized in that the melt is given a predominantly horizontal flow direction in the area near the stopper, and that by changing the angle of rotation of the at least approximately horizontal outlet opening of the stopper, the inflow direction into the stopper is continuously changed during the outflow from the vessel.

By actuating the stopper by means of a rod protruding into the melting vessel from above, the actuating mechanism can be designed extremely easily. There are no moving fixtures beneath the bottom of the melting vessel, which are annoying due to their space requirement and which are endangered in their movement function under the influence of heat and metal splashes. Since the stopper is subjected to pressure in the closing direction, there is a high degree of locking security, in contrast to a stopper actuation from below, in which the closing force requires the stopper to be subjected to tensile stress and the refractory materials - compared to their compressive strength - only have a significantly lower tensile strength to have.

The plug and the bore in the pouring spout can be precisely manufactured using conventional manufacturing methods. To achieve an effective seal, the plug must fit into the bore of the pouring spout with virtually no play. The high-heat-resistant materials used generally have a high compressive strength, but only a low flexural strength. This results in problems with the plug assembly together with the relatively long rod, since if the actuating rod is not exactly aligned with the pin, bending forces occur which would either cause the plug seat to jam or even lead to the plug being broken off. It should also be noted that heat distortion can occur both in the rod and on the vessel under the heat of fusion, which can lead to a slight curvature of the rod and thus to its bending stress, for example. These problems are remedied by the fact that the rod is articulated and the rod is opposite the surrounding one, plug neck immersed in the melt has radial play. This means that both inaccuracies in assembly and heat distortion can be compensated for without the plug being subjected to bending.

A first seal is obtained in a manner known per se, in that, in the closed position, a conical shoulder rests against the edge of the bore of the outflow pipe. The breakthrough security for the melt is greatly increased by a second, cumulative sealing device. This consists in that a ring part which is closed on the jacket and which forms the second seal together with the bore is present on the pin between its throttle opening and the conical sealing surface located above it. This results in improved security against leakage, since the two seals take effect one after the other and only after a stroke movement of the stopper corresponding to the ring width V has been covered. As a result, even erosion remains at the throttle opening of the stopper without adverse consequences for the reliable sealing of the outlet opening, so that expensive emergency shutters can be avoided. Such stopper devices with a reliable sealing function have a longer service life, as a result of which the operating costs can be reduced.

A good control characteristic for the flow of the melt results from the fact that the amount of molten metal flowing out per unit of time can be adjusted and metered directly by the stroke of the stopper, which in particular makes casting on easier. In this way, conventional sand filling, which results in an undesired admixture, can be dispensed with.

When casting metallurgical melts, there is the well-known problem of preventing slag and non-metallic bullets from running along.

In the casting method according to the invention, the largely horizontal direction of flow calms the melt, which favors the elimination of non-metallic inclusions that slowly rise to the surface. In addition, the melt layer near the bottom of the vessel is removed during casting. This prevents premature slag running above a minimum bath level. The largely horizontal flow direction is favored by the radial arrangement of the single throttle opening in the stopper together with the possibility of rotation. Since the horizontal pouring spout can be rotated during the pouring process, the flow conditions of the respective vessel shape, the different bath height, the melt temperature and other parameters can be adjusted from case to case. As a result of the calmed down pouring flow through the pouring distributor, there are no rebounding waves of the melt from the floor, which prevents the floating of the floating slag layer that prevents reoxidation. The calm flow eased and also accelerates the rise of non-metallic inclusions to the surface of the melt.

• Fig. 1 einen Schnitt durch die Vorrichtung samt Schmelzgefäss
• Fig. 2 einen Teilschnitt durch den Stopfen in seiner in die Ausgussöffnung hineinragenden, geschlossenen Stellung
• Fig. 3 einen Schnitt durch den Stopfen in seiner offenen Stellung
• Fig. 4 einen Querschnitt durch eine Ausführungsvariante in Richtung der pfeile IV-IV in Fig. 5
• Fig. 5 einen Längsschnitt durch die Ausführungsvariante gemäss Fig. 4 mit einer Vielzahl von Drosselöffnungen
• Fig. 6 einen Querschnitt durch eine weitere Ausführungsvariante mit zueinander versetzten Drosselöffnungen zur Erzeugung eines Dralles für die ausfliessende Schmelze
• Fig. 7 einen Längsschnitt durch ein als Zwischenbehälter ausgebildetes Gefäss, mit Eingussverteiler und mehreren Stopfen
• Fig. 8 eine Draufsicht auf den Zwischenbehälter gemäss Fig. 7 mit Darstellung unterschiedlicher Drehlagen der Ausgussöffnungen der Stopfen im Schnitt
• Fig. 9 einen Querschnitt durch den Zwischenbehälter gemäss Fig. 7 mit starker Querschnittsverjüngung nach unten.

Exemplary embodiments of the invention are shown in the drawing. Show it:

• Fig. 1 shows a section through the device including the melting vessel
• Fig. 2 is a partial section through the stopper in its protruding into the pouring opening, closed position
• Fig. 3 shows a section through the stopper in its open position
• 4 shows a cross section through an embodiment variant in the direction of the arrows IV-IV in FIG. 5
• 5 shows a longitudinal section through the embodiment variant according to FIG. 4 with a large number of throttle openings
• Fig. 6 shows a cross section through a further embodiment with staggered throttle openings for generating a swirl for the outflowing melt
• 7 shows a longitudinal section through a vessel designed as an intermediate container, with a pouring distributor and several plugs
• Fig. 8 is a plan view of the intermediate container of FIG. 7, showing different rotational positions of the pouring openings of the plugs in section
• FIG. 9 shows a cross section through the intermediate container according to FIG. 7 with a strong cross-sectional taper downwards.

1, in the bottom 2 of a vessel 1 for receiving a metal melt, there is an outlet opening with an outlet pipe 3 open at the bottom. A plug 6 of refractory material, with which the flow of the melt regulates, projects into the bore 7 of this outlet pipe 3 and is closed or can be opened.

A stopper rod 5 projects into the stopper neck 10, with which the stopper 6 can be moved in the vertical direction and rotated about its axis. The drive is effected by a drive device 17 located outside the vessel 1. The vertical drive can consist of a mechanical, motor-driven spindle 8 or a hydraulic or pneumatic lifting cylinder. A horizontal arm 23 is connected to the vertical guide member 9 above the edge of the vessel. The connection of the arm 23 with the upper end of the plug rod 5 and below with the bell-like plug head 24 takes place by means of a coupling ball 11. The plug rod 5 held in the plug neck 10 has radial play. The rotary drive device 17 provided for rotating the plug 6 about its vertical axis is connected to a drive motor (not shown in more detail). This motor can be a servo or stepping motor, with which different rotational positions of the plug 6 can be programmed and reproduced. The rotational position of the plug 6 could also be changed by pneumatic or hydraulic rotary drives.

The plug 6 contains a cylindrical pin 13 which engages in a bore 7 of the outlet channel 4. This pin 13 is provided with a horizontal radial throttle opening 14 which opens into an axially open bore part 12 and merges into the pouring channel 4. Since the pin 13 is only open radially on one side, the outflowing metal melt is forced onto a predetermined direction of flow, which is indicated by the line S in FIG. 1. In the area in front of the pouring opening, together with the bell-like plug head 24, which is larger in diameter than the pin 13, the aim is to achieve a flow that is as horizontal as possible in order to prevent eddy formation of the melt and thus slag suction from above. By rotating the plug 6 about its vertical axis, the direction of flow can also be influenced step by step or continuously during the casting process. By lowering the plug 6, the flow cross section of the throttle opening is reduced or completely closed.

The stopper rod 23 can be fixed with the upper coupling ball 11 of the stopper rod 5 automatically with a clamping device. As a result, the plug rod 5, which can move with play, and the plug 6 located in its lower end need not be precisely aligned before assembly. A stopper neck 10 surrounding the stopper rod 5 serves as protection against the melt. Since the control forces are directed directly into the head of the plug 6 via the plug rod 23, the plug 6 is protected from bending forces by alignment errors. The otherwise usual alignment work for the stopper 6 is dispensed with and the stopper can also be used automatically in hot metallurgical vessels, which results in a reduction in the vessel circulation times and thus maintenance costs are saved.

The design of an embodiment variant of the plug 6 in the closed and in the open position is described in more detail with reference to FIGS. 2 and 3. The stopper 6 contains a cylindrical or slightly conical spigot 13 projecting into the bore 7 of the pouring tube 3. In contrast to the embodiment according to FIG. 1, this spigot 13 contains a plurality of radial throttle openings 14. These are evenly distributed on the circumference of the spigot. The upper and the lower region of these throttle openings 14 are each wedge-shaped, while the middle region of these throttle openings 14 contains parallel vertical side walls 18. The longitudinal axes of the throttle openings 14 extend in the vertical direction, ie in the direction of the stopper movement. As a result, a control characteristic that is more advantageous than round throttle openings can be achieved. The throttle openings 14 open into the central longitudinal bore part 15 of the pin 13 which is open at the bottom. Above the throttle openings 14, the pin 13 merges into a frustoconical widening 16, which is a frustoconical Barrier forms. The central angle of this shut-off surface forms an angle of 75 ° to 105 °, preferably 90 °. Together with a frustoconical countersink 18 at the upper edge of the bore 7 at the same angle, this results in an annular first seal 20. Between the uppermost edges of the throttle openings 14 and the frustoconical shut-off surface 16 there is a closed, cylindrical ring part 19 with the width V on the pin 13 (Fig. 3). When the plug 6 is closed, that is to say lowered, this ring part 19 together with the adjacent cylindrical bore 7 with the same diameter results in a second seal 21. The lowermost part of the pin 13 is likewise designed as a ring part 22 closed on the jacket, so that the pin 13 is in the bore 7 remains guided, even if the throttle openings 14 are fully open.

Since the throttle openings 14 are not in contact with the melt in the closed position of the plug 6 according to FIG. 2, there is no danger that the melt can freeze in this area. Above the frustoconical widening 16, the plug head 24 is expanded in a bell shape. When the stopper 6 is closed, the approximately horizontal lower edge 26 of the widened stopper head 24 is at a relatively large distance from the horizontal surface 28 of the pouring tube 3 projecting beyond the bottom of the vessel, so that a relatively wide annular space 30 for the melt results in front of the first seal 20. This relatively large mass of the melt surrounding the bore 7 reduces its cooling and counteracts blockage. The design of the stopper head 24, together with the horizontal arrangement of the throttle opening, also favors an approximately horizontal flow of the flowing melt, as indicated by arrows A in FIG. 3. This prevents eddy formation in the melt even when the melt is low in the vessel, so that slag is not prematurely drawn into the pouring spout. In addition, this annulus 30 or the like by argon. be rinsed, which can be supplied via thin feed lines 33 in the plug 6. This feed line 33 can also be used to generate a control signal. As soon as the outlet end emerges from the melt, there is a pressure drop in the gas of the feed line. This allows the casting process to be interrupted before slag is carried along.

Since there are two seals that come into effect one after the other, there is increased security against breakthroughs of the melt, even if the surface 16 or the countersink 18 of the first seal 20 should be damaged by wear.

The second seal (21) can also be kept free of penetrating melt by blowing gas through bores (34).

4 and 5, an embodiment variant is shown in which the throttle openings in the plug 6 from a plurality of relatively small radial Holes 14 'are formed on the circumference, which are arranged one above the other in axial rows. This causes the melt to be filtered. When the upper holes 14 'or rows of holes close, the plug 6 is raised further, so that new, still open holes are released for the flow and the filtering.

In the embodiment variant according to FIG. 6, two throttle openings 14 ″ are arranged on opposite sides of the pin 13 and are offset from one another with respect to the central axis, so that they run approximately tangentially to the longitudinal outlet opening 15. This creates a swirl in the flowing out melt according to the arrows, which prevents deposits on the walls of the spout, since the lighter inclusions remain in the center of the vortex.

7, 8 and 9 show an embodiment variant in which the vessel 1 is designed as an intermediate container with a pouring distributor 30 and a plurality of pouring plugs 6 which can be rotated independently of one another. A problem with such distribution vessels or intermediate containers with several pouring openings is that that the melt temperature is different due to different lengths of passageways, which is undesirable. By immersing the pouring distributor 30 in the melt and the directed and rotatable, predominantly horizontal pouring opening 32 below the bath level, an approximately horizontal outlet of the melt and a calmed flow pattern approximately in the sense of the flow paths T in FIGS. 7, 8 and 9 result The course of the flow depends on the inflow angle β of the pouring distributor 30 and on the outflow angles α of the plugs 6. The flow vectors of the pouring and the pouring spouts generate a torque in the melt, as a result of which the individual melting elements sink from the hot surface layer near the surface to the colder layer near the ground. Due to the helical flow pattern, a passage path of the same length is sought for all throttle openings 14 in order to avoid temperature differences. The flow paths T shown schematically in FIGS. 7, 8 and 9 will not be strictly observable in practice, but due to the mixing of the melt with partial flows, there is a good temperature distribution and the avoidance of dead zones. 7 and 8, only one half of such an intermediate container is shown.

The residence time of the melt in the vessel 1 can be influenced by a suitable choice of the angles α and β. Due to the calming flow, non-metallic inclusions have the opportunity to quickly rise to the surface in the floating slag layer through their own buoyancy, so that they are not dragged into the outlet channel by turbulence. This also applies to slags. Due to the forced, essentially horizontal flow in the pouring area of the metallurgical vessel 1, eddies and thus a premature slag run are avoided. This improves the quality of the end product, reduces scrap and increases production.

9 shows the cross section through the intermediate container, from which it can be seen that the walls are strongly inclined, as a result of which a preferred flow path is forced.

The individual plugs 6 according to FIGS. 7-9 correspond to those according to FIG. 1 and can thus be raised, lowered and rotated, as was explained in connection with FIG. 1. The control can be carried out individually or together using a predetermined program, depending on casting parameters such as temperature, throughput, analysis. Data processing systems can also be used for this. The sprue distributor 30 can also be included in such a program control, i.e. the angle β and / or its altitude can be changed. The throttle cross sections of the plugs 6 can also be individually regulated by raising or lowering them.

Claims (17)

1. A discharge and flow control device for a vessel for molten metal, which comprises an outlet pipe (3) located on the vessel floor and having a discharge aperture, with a stopper cooperating with the outlet pipe, and in its closed position the stopper (6) comprises a journal (13) projecting into the bore (7) of the outlet pipe, which is at least roughly cylindrical and serves as a shut-off device, which on its periphery contains at least one radial throttle aperture (14) which extends into a longitudinal duct (15) of the journal (13) which is open at the bottom, and between stopper (6) and outlet pipe (3) above the throttle aperture (14) there is a first seal (16; 18) which can be closed by lowering the stopper (6), characterised in that the stopper (6) is located at the lower end of a height-adjustable rod (5) projecting from above into the interior of the vessel, the rod (5) is jointed and has radial clearance with respect to the stopper neck (10) surrounding it and, between its radial throttle aperture (14) and the sealing surface (16) above it, the journal (13) contains an annular part (19) closed on the shell, which forms a second seal (21) together with the adjacent part of the bore (7).
2. A device according to Claim 1, characterised in that directly above the annular part (19) there is a closing surface (16) in the shape of a truncated cone and the upper edge of the bore (7) contains a countersinking (18) in the outlet pipe (3), which together with the closing surface (16) forms the first seal (20).
3. A device according to Claim 1 or 2, characterised in that the journal (13) only contains a single throttle aperture (14), which is substantially horizontal and radially disposed.
4. A device according to Claim 1 or 2, characterised in that the journal (13) contains several substantially horizontal radial throttle apertures (14) distributed over the periphery.
5. A device according to Claim 1 or 2, characterised in that the throttle aperture(s) (14) is (are) constructed in a wedge-shape at least on the upper end and an adjacent oblong aperture region has parallel lateral surfaces (35).
6. A device according to one of Claims 1-5, characterised in that above the closing surface (16) in the shape of a truncated cone the stopper (6) comprises a bell-shaped or mushroom-shaped stopper head (24).
7. A device according to Claim 1, characterised in that the journal (13) has several rows of holes disposed above one another along its periphery, which are uncovered as the upward movement of the stopper (6) progresses.
8. A device according to Claims 1, 2 or 6, characterised in that there are one or several throttle apertures (14) discharging tangentially into the longitudinal aperture (15).
9. A device according to one of Claims 1-8, characterised in that in the uppermost part of the outlet pipe (3) there are bores (34) for blowing in gas.
10. A device according to Claim 3, characterised in that there are adjustment means (17) for rotating the stopper (6).
11. A device according to Claim 10, characterised in that the vessel (1) is an intermediate container, into which a pouring distributor (30) having a roughly horizontal pouring-in hole (32) projects, and in that the pouring distributor (30) is provided with a drive appliance (25) for height adjustment and/or a drive appliance (26) for rotation around its longitudinal axis.
12. A device according to one of Claims 1-11, characterised in that at least one bore (33) for blowing in gas or powder discharges in the stopper (6) above the journal (13).
13. A casting process for casting molten metal from a metallurgical vessel (1), which contains at least one outlet aperture located on the vessel floor, which cooperates with a stopper (6) by forming sealing organs, with the molten metal flowing out in the opened stopper position via at least one roughly horizontal outlet aperture (14) in the stopper (6) and its longitudinal duct (15) open at the bottom, characterised in that in the region near the stopper the molten metal is given a predominantly horizontal direction of flow and in that by changing the position of the angle of rotation (α) of the at least roughly horizontal outlet aperture (14) of the stopper (6) the direction of flowing in is continually changed during the flow from the vessel (1).
14. A casting process according to Claim 13, characterised in that in addition the pouring flow of the molten metal into the vessel (1) is directed predominantly horizontally.
15. A casting process according to Claim 14, characterised in that the pouring flow is continually changed with respect to the height and angle of rotation (β) relative to the vessel (1) during the casting operation.
16. A casting process according to Claim 13, characterised in that the angle of rotation (α) of the outlet aperture (14) and/or the angle of rotation (β) of the pouring-in hole (32) is automatically changed as a function of at least one specified value or a specified programme.
17. A casting process according to Claim 13, characterised in that there are several stoppers (6) which are adjusted with respect to the height and/or angle of rotation individually.

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