Abstract: A double-acting switch valve includes a mounting bracket and two mutually backup sealing assemblies disposed on the mounting bracket, each of the two sealing assemblies including a carbon rod and a carbon rod moving assembly, the carbon rod moving assembly being configured to translate, and elevate or lower the carbon rod so as to block or open a metal liquid channel between two metal liquid furnaces. Two sealing assemblies which are mutually replaceable, where when the carbon rod on one of the sealing assemblies is worn down, the other sealing assembly may take its place to block the metal liquid outlet again via the carbon rod; and then the worn-down carbon rod is renewed. This design eliminates the time taken for replacing the carbon rod and can reduce the amount of the metal liquid discharged via the metal liquid outlet during replacement of the carbon rod.

Abstract: Drive device for a stopper closure on a metallurgical vessel, including a housing arranged on the vessel in a removable manner, an adjustment system mounted in the housing so as to be height-displaceable and has a drive which can be coupled to the housing, and an upper connection element for a support arm carrying the fire-proof stopper. The adjustment system for the stopper is mounted so as to be height-displaceable on at least one bearing shaft fastened in the housing. This design of the adjustment system permits an increase in the stiffness of the drive device and hence of the fire-proof stopper suspended by the drive device on the support arm during pouring.

Abstract: A casting method of an active metal includes, in an induction melting furnace using a water-cooled crucible, tapping a molten metal into a mold from a tapping hole provided at a bottom of the water-cooled copper crucible to cast an ingot of the active metal. In conducting the casting under a casting condition in which the ingot has a diameter (D) of 10 mm or more and a ratio (H/D) of an ingot height H to the ingot diameter D of 1.5 or more and a weight of the molten metal tapped in the casting is 200 kg or less, a temperature of the molten metal in the casting is set to be higher than the melting point of the active metal and a casting velocity V (mm/sec) is controlled to satisfy V?0.1H in relation with the ingot height H by adjusting an opening diameter of the tapping hole.

Abstract: A bubble pump is provided. The bubble pump has an interior formed from a material that is resistant to attack by molten aluminum. The interior surface may be formed from a ceramic. The ceramic may be selected from the following: alumina, magnesia, silicate, silicon carbide, or graphite, and the mixtures thereof. The ceramic may be a carbon-free, 85% Al2O3 phosphate bonded castable refractory.

Abstract: A bubble pump having a steel tube pump body having an interior formed from a ceramic material that resists attack by molten metal. The pump further has a nitrogen supply line attached to a lower portion of the pump body. The pump body and nitrogen supply line are covered with a ceramic cloth material that resists attack by molten metal. The pump also includes a discharge head attached to the top of the pump body. The discharge head is formed of a cast ceramic material that resists attack by molten metal and includes a distribution chamber therein which has an ellipsoidal dome shape with a generally flat bottom and an ellipsoidal top. The discharge head also includes two discharge nozzles which have a square cross section. These features provide the inventive pump with extended service life and reduced discharge turbulence of the molten metal.

Abstract: A molten metal holding and pouring box with a rectangular-shaped upper section and a pyramidal-shaped lower section provides a relatively constant flow of molten metal being poured from the box through each of two bottom nozzles into two separate foundry molds at the same time. The two bottom nozzles are contained in a unitary dual nozzle assembly that facilitates replacement as required by wear, or a change in location of the sprue cups in the two separate foundry molds being filled with molten metal.

Abstract: The invention relates to a ceramic refractory stopper (a stopper device) for controlling a flow of molten metal at an outlet opening of a metallurgical vessel, such as a tundish.

Abstract: A stopper rod having an elongate trunk with an upstream first end and a downstream second end, a continuous axial bore extending through the trunk from a stopper inlet in the upstream first end to a stopper outlet in the downstream second end, and a flow control device disposed within the bore to create a backpressure upstream thereof. The flow control device includes a body having an inlet, an outlet and a passageway therebetween, a wire positioned substantially axially in the passageway, and a retainer for maintaining the wire in the passageway. In one embodiment, the retainer is constituted by a portion of the wire itself, which is bent or crimped or configured as a loop; kink or spiral which prevents the wire from being dislodged from the passageway.

Abstract: Nozzle for guiding molten metal, including an inlet at an upstream first end, at least one outlet towards a downstream second end, and an inner surface between the inlet and the outlet defining a bore through the nozzle having a throat region adjacent the inlet. An annular channel is provided in the inner surface of the nozzle, and a fluid supply is arranged to introduce fluid into the bore via the annular channel or downstream thereof. The throat region has a convexly curved surface and the annular channel is located within or adjacent the convexly curved surface of the throat region.

Abstract: In continuous casting of steel, the flow out of the tap hole (11) in the tundish (10) is controlled by a stopper rod that is rotatable so as to give the molten steel a swirling motion. This rotation reduces the risk of deposits in the tap hole and in the discharge tube (12). A non-rotatable sleeve around the stopper rod (16) extends through the slag layer (18) and into the molten steel (17). Protective gas is supplied to the gap between the stopper rod (16) and the sleeve (30) to prevent air from being drawn through the gap and into the molten steel.

Abstract: A stopper rod positioning and control apparatus is provided for controlling the flow of a molten metal out of a bottom nozzle in a metal reservoir. The stopper rod can be aligned with the nozzle's opening by selectively rotating a pair of roller (ring) bearings that are centerline offset from each other along a first axis around which one end of an extended structural arm can pivot where the opposing end of the arm retains the stopper rod along a second axis parallel to the first axis. When the appropriate relative positions of the pair of roller bearings are located for a nozzle-centered stopper rod, the second axial position of the stopper rod is fixed by retaining the appropriate relative positions with a brake mechanism.

Abstract: In continuous casting of steel, the flow out of the tap hole (11) in the tundish (10) is controlled by a stopper rod that is rotatable so as to give the molten steel a swirling motion. This rotation reduces the risk of depositions in the tap hole and in the discharge tube (12). A sleeve around the stopper rod (16) extends through the slag layer (18) and into the molten steel (17). Protective gas is supplied to the gap between the stopper rod (16) and the sleeve (30) to prevent air from being drawn through the gap and into the molten steel.

Abstract: A slag control shape is releasably mounted on a mounted member carried on a molten vessel or an adjacent base. The mounted member includes an L-shaped bracket carrying a movable member to release the slag control shape and an actuator for selectively releasing the slag control shape. The mounting member further includes a sleeve secured to the vessel or adjacent base. A rotating shaft is connectable to both the L-shaped bracket and sleeve to provide rotatable movement in selective positions, of the L-shaped bracket relative to the sleeve.

Abstract: A stopper body of refractory material and cylindrical shape having a first end (10), a second end (14) and an intermediate zone (12) there between, with a bore (16) of circular cross section, extending from said first end (10) in an axial direction of the stopper body into said intermediate zone (12) towards the second end (14), wherein the said bore being provided with an enlarged cross section (at 16s) along at least part of said intermediate Zone (12).

Abstract: A stopper rod comprises an elongate body having an inlet at an upper first end and an outlet at a lower second end. The second end of the body defining a nose for insertion into a tundish outlet. A continuous axial bore extends through the body from the inlet in the first end to the outlet in the second end. A restrictor having an inlet, an outlet and a passageway therebetween, is positioned in the axial bore such that the inlet of the restrictor is closer to the first end than the second end. A gas supply conduit is arranged to supply gas into the axial bore above the inlet of the restrictor.

Abstract: Stopper rod having an elongated body of refractory material, a passageway extending longitudinally in the body from an end thereof which is uppermost in use, a carrier rod having a part fixedly received in the passageway and a further part outside of the passageway for attachment to a lifting device for the stopper rod. The passageway has an enlarged part which defines a sealing surface spaced from the end of the body, an insert around the carrier rod having at least a part thereof received in the enlarged part, a retention element on the carrier rod, and an expandable element disposed between the insert and the retention element. The material of the insert has a co-efficient of thermal expansion no greater than that of the carrier rod. Expansion of the expandable element, in use, is greater than that of the carrier rod.

Abstract: The invention relates to a stopper for a metallurgical melting pot with. Stoppers of this type serve to control the discharge of a molten metal in the area of an outlet of an associated melting pot, for example, a tundish.

Abstract: A stopper rod positioning and control apparatus is provided for controlling the flow of a molten metal out of a bottom nozzle in a metal reservoir. The stopper rod can be aligned with the nozzle's opening by selectively rotating a pair of roller (ring) bearings that are centerline offset from each other along a first axis around which one end of an extended structural arm can pivot where the opposing end of the arm retains the stopper rod along a second axis parallel to the first axis. When the appropriate relative positions of the pair of roller bearings are located for a nozzle-centered stopper rod, the second axial position of the stopper rod is fixed by retaining the appropriate relative positions with a brake mechanism.

Abstract: A slag control shape is releasably mounted on a mounted member carried on a molten vessel or an adjacent base. The mounted member includes an L-shaped bracket carrying a movable member to release the slag control shape and an actuator for selectively releasing the slag control shape. The mounting member further includes a sleeve secured to the vessel or adjacent base. A rotating shaft is connectable to both the L-shaped bracket and sleeve to provide rotatable movement in selective positions, of the L-shaped bracket relative to the sleeve.

Abstract: The present invention provides a stopper structure capable of preventing loosening of a shaft rod during use, and gas leakage which is likely to occur when the stopper structure is designed to allow gas to pass therethrough. The shaft rod 1 is adapted to be mounted in a mounting hole 2a of a refractory stopper 2, and formed to have an outer peripheral surface including a first tapered sub-surface 4a which increases in diameter toward an axially lower edge of the shaft rod. The mounting hole 2a of the refractory stopper 2 is formed to have an inner surface including a second tapered sub-surface 4b adapted to come into surface contact with the first tapered sub-surface 4a. The shaft rod 1 is adapted to be fastened to the refractory stopper so as to allow the first tapered sub-surface 4a to be brought into close surface contact with the second tapered sub-surface 4b.

Abstract: Control device for a stopper-rod to regulate the outflow of liquid metal through a calibrated hole of a pouring receptacle comprising motor means, suitable to operate lifting and lowering means (2) of the stopper (4) by means of first driving means (7) and second driving means (14, 14?), the latter being suitable to convert a rotating motion into a translational motion, wherein the second driving means are flexible longitudinal elements and are fixed at a first end thereof to lifting and lowering means and a second end thereof to an anchor element (9), integral with the first means.

Abstract: A stopper rod comprises a body (11) having a central passageway (12) with part of a carrier rod (13) fixed in the passageway and a further part outside of the passageway for attachment to a lifting device. An enlarged part of the passageway defines a sealing surface (14) and an insert (16) around the carrier rod is partly received in the enlarged part. Retention means (17, 18) are carried on the carrier rod and expandable means are disposed around the carrier rod between the insert (16) and the retention means (17, 18). The expandable means include an expandable graphitic composition formed by removing a proportion of interstitial water from an expandable graphite formulation. The insert has a co-efficient of thermal expansion no greater than that of the carrier rod, whilst expansion of the expandable means is greater than that of the carrier rod.

Abstract: Provided is a nozzle unit for use in a bonding device in which bonding between a first member and a second member is effected by providing a bonding member that has been melted by heating at a bonding position where the first member and the second member are to be bonded to each other. The nozzle unit includes: a cylindrical nozzle assembly having an accommodating space accommodating the bonding member, and an opening which allows ejection of the bonding member accommodated in the accommodating space onto the bonding position, which has a diameter larger than the diameter of the bonding member, and which communicates with the accommodating space; and a holding/releasing member for releasably holding the bonding member within the accommodating space.

Abstract: The present invention concerns stopper rod system for use in a metallurgical vessel, comprising a stopper rod and a nozzle. At least one of the stopper rod nose and the internal surface of the nozzle bore comprise a plurality of ripples that are arranged such that the size of a flow channel between the stopper rod nose and the internal stopper rod when the stopper rod system is in an open position discontinuously increases in size as a function of the distance downstream from the point of contact between the stopper rod and the nozzle.

Abstract: Control device for a stopper-rod to regulate the outflow of liquid metal through a calibrated hole of a pouring receptacle comprising motor means, suitable to operate lifting and lowering means (2) of the stopper (4) by means of first driving means (7) and second driving means (14, 14?), the latter being suitable to convert a rotating motion into a translational motion, wherein the second driving means are flexible longitudinal elements and are fixed at a first end thereof to lifting and lowering means and a second end thereof to an anchor element (9), integral with the first means.

Abstract: The present invention concerns a mono-block stopper adapted to deliver gas during pouring of molten metal comprising a stopper body having an internal chamber (1) and a gas discharge port (2), a bore (3) connecting the internal chamber (1) to the gas discharge port (2), calibrating means (4) being provided in the bore (3) to provide a restricted path. This stopper is characterised by the fact that the calibrating means comprise a rod (4) having at least one axially-extending gas passages therealong, the gas passage(s) having a section such as to offer a predetermined resistance to flow. The stopper of the invention is far more reliable and can be easily adapted to various operational parameters.

Abstract: A refractory article such as a stopper used in the casting of molten metals that consists of a refractory core coated with an electrically conductive layer of carbon and graphite materials such that the stopper withstands the mechanical, chemical and thermal rigors of the casting operation and provides an effective electrical contact during the molten metal casting process.

Abstract: A control assembly for controlling reciprocal motion of a stopper used with a tundish dish including a shaft movably guided within a guiding assembly and connected to the stopper and wherein a motor is movable between a first postion wherein output from the motor is disengaged from a motion converting device connected to the shaft and a second position wherein the motor is drivingly engaged with the motion converting device. A linking device is also provided to secure the motor relative to the motion converting device in the second position thereof.

Abstract: There is provided a refractory mono-block stopper of substantially cylindrical configuration having an upper end, a lower end and an axial bore extending downwardly from the upper end, means being provided in the axial bore at a distance d from the upper end for attachment of the stopper to a lifting mechanism, the stopper being divided into three portions (A,B,C); a first portion (A) extending from the upper end towards the lower end until a distance greater than d, a second portion (B) extending from the first portion (A) towards the lower end and a third portion (C) extending from the second portion (B) and comprising a stopper nose ending at the lower end of the stopper. The stopper of the invention is characterized in that the average section of the second portion (B) is lower than the section of the first portion (A) and the highest section of the third portion (C) is higher than the lowest section of the second portion (B).

Abstract: Apparatus for pouring of molten metal from a vessel onto the gating system of a mold includes a shield assembly that diverts any abnormal flow of molten metal occurring between normal flow of molten metal onto the gating system when molds are indexed for pouring. The shield assembly protects sensitive components of the mold, such as the gating and casting patterns in a lost foam casting process, from abnormal flow of molten metal.

Abstract: A holding structure for a continuous casting long stopper includes a continuous casting long stopper including a shaft insertion hole formed in an upper end thereof, a protrusion insertion groove contiguous to and axially opposed to the shaft insertion hole, and a horizontal engagement groove contiguous to a lower end of the protrusion insertion groove, and a holding rod including a shaft inserted into the shaft insertion hole, the shaft having a lower end on which a radially protruding locking protrusion is formed. In the structure, after the shaft of the holding rod is inserted into the shaft insertion hole such that the locking protrusion reaches the protrusion insertion groove, the locking protrusion is caused to engage the engagement groove by rotation of either the shaft of the holding rod or the long stopper relative to the other.

Abstract: The invention concerns a stopper rod with a cylindrical stopper rod body comprising a fire-resistant, carbon-containing material, having a base part and a nose-like section made of a different fire-resistant material than the base part, whereby an interface extends between the nose-like section and the base part over the entire cross-section of the stopper rod body, wherein the nose-like section comprises a fire-resistant material wherein the carbon content burns out under oxidic atmosphere above 90° C., at least close to a surface area.

Abstract: A stopper for continuous casting comprising a stopper rod and a spindle for actuating the stopper rod, wherein the stopper rod includes a joining nut integrally formed therewith, an upper end surface of the stopper rod being formed so as to be smooth, and a pin hole being provided in the upper end surface so as to prevent from rotating, while the spindle includes a gas introduction route, a male screw provided in a tip portion thereof for being engaged with the joining nut, a male screw provided in an upper portion thereof for being engaged with a fastening nut for fixing the spindle to the stopper rod, and a flange tightly adhered to the upper end surface of the stopper rod and provided with a hole, into which a pin for preventing rotation is inserted. The spindle is fixed to the stopper rod by the joining nut. The flange is fixed to the upper end surface of the stopper rod by the fastening nut so as to be hermetically sealed.

Abstract: The present invention concerns a stopper rod whose gas tightness and rigidity are improved. In particular, the stopper rod of the present. invention has means for maintaining the compression of the sealing gasket (11, 11′) in contact with the annular sealing surface (10) of the body of refractory material when the stopper rod is brought to a high temperature. According to one embodiment of the invention, these means are furnished by a sleeve (12) comprised of a material with a high coefficient of thermal expansion, the dilatation of which maintains the sealing gasket under compression when the stopper rod is brought to a high temperature.

Abstract: The present invention concerns a one-piece stopper rod whose gas tightness is improved. In particular, the stopper rod of the present invention has a body of refractory material comprised at least partially of a refractory material relatively impermeable to gases.

Abstract: A coupling mechanism for a molten metal processing system includes an elongated shaft having an upper axial end and a lower axial end. A passage having a torque facilitating shape extends through at least a portion of the shaft. The upper end of the shaft tapers inwardly and forms a tapered seat. At least one channel is machined into an outer surface of the upper end of the shaft. The channel has a first portion extending longitudinally downward from a top surface of the shaft and a second portion extending from the first portion at an angle greater than 90° relative to the first portion. A coupling member, for coupling the shaft to a drive system, includes a body having an annular wall which defines a cavity. At least one locking member is disposed on an inner surface of the annular wall which is adapted to cooperate with the channel in the shaft. The locking member is aligned with the first portion of the channel and the shaft is slid into the cavity.

Abstract: A stopper for continuous casting comprising a stopper rod and a spindle for actuating the stopper rod, wherein the stopper rod includes a joining nut integrally formed therewith, an upper end surface of the stopper rod being formed so as to be smooth, and a pin hole being provided in the upper end surface so as to prevent from rotating, while the spindle includes a gas introduction route, a male screw provided in a tip portion thereof for being engaged with the joining nut, a male screw provided in an upper portion thereof for being engaged with a fastening nut for fixing the spindle to the stopper rod, and a flange tightly adhered to the upper end surface of the stopper rod and provided with a hole, into which a pin for preventing rotation is inserted. The spindle is fixed to the stopper rod by the joining nut. The flange is fixed to the upper end surface of the stopper rod by the fastening nut so as to be hermetically sealed.

Abstract: An opening 206 is provided in a system for delivering molten metal to the mold cavity 18 of a molten metal casting apparatus. A valve closure device 192, 196 is mounted at 198 to be reciprocated in relation to the opening 206 to control the flow of molten metal therethrough, and the driven end 206 of a bellows motor 208 is connected with the valve closure device at 258 to reciprocate the device in relation to the opening. A pair of concentric relatively inside and outside thimble-shaped chambers 238 and 240, 264 is circumposed about the bellows motor so that the bight portions thereof are opposed to the driven end of the motor, and interconnected with one another by a restricted liquid flow passage 270 in the screw 268. When fluid input signals are generated in the relatively outside chamber 240, 264, for the actuation of the closure device through the bellows motor, each signal is transmitted to the end of the bellows motor through the restricted liquid flow passage 270 and the relatively inside chamber 238.

Abstract: A stopper rod in the form of an elongate molded body having a longitudinal bore has an attachment device for attaching the stopper rod to a lifting and lowering mechanism.

Abstract: A method for supplying molten metal alloy for producing thin amorphous metal wire or thin amorphous metal strip by liquid quenching and solidification on a moving cooling substrate controls the flow of molten metal from a ladle into a tundish. The ladle has a long nozzle with an interior passage for providing flow of molten metal alloy into the tundish. The ladle stopper has a distal end region received by the interior passage of the long nozzle. Control of the overlap between the distal end region of the ladle stopper received in the long nozzle during molten alloy flow and control of the sectional flow area provided in the long nozzle interior passage controls the flow quantity of molten alloy from the ladle into the tundish.

Abstract: A melting crucible (1) comprises a collecting volume (6) for liquid material and is equipped with a bottom outlet opening (2). This bottom outlet opening (2) is closable with a movable stopper (3). The bottom outlet opening (2) comprises a specially formed transition region (7), and the front end of stopper (3) is also specially formed. This shaping leads to improved flow conditions and to optimum sealing between stopper (3) and melting crucible (1).

Abstract: A process for closing a tap hole in a metallurgical vessel at least partially filled with a metal melt includes bringing a compressible fire-resistant material to the moth of a tubular closing element, providing a medium that substantially prevents contact between the fire resistant material and the metal melt, passing the closing element through the melt toward the bottom of the vessel, compressing the compressible material against the bottom of the vessel to form a seal between the outside of the closing element and the tap hole below the closing element, and moving a cut off device over the outside of the tap hole, thereby allowing the tap hole to be filled with a pourable refractory compound via the tubular closing element. A device for performing the process for closing a tap hole includes a tubular closing device with a groove at an end bottom facing the bottom of the metallurgical vessel.

Abstract: A prefabricated sleeve is adapted to be used in a molten metal pouring container comprising at least one pouring orifice in the form of a substantially frustoconical hole into which a pouring nozzle is inserted axially. The sleeve is inserted into an annular space formed between the hole and the outside of the nozzle for fixing the nozzle into the hole. The sleeve is prefabricated from inorganic particles bound together by a binder that has a predetermined rate of deterioration at the temperatures present during pouring of the molten metal.

Abstract: The object of the present invention is to provide a tundish stopper rod for continuous casting which can be fitted onto a spindle correctly in a short time and which has a sufficiently high degree of heat resistance and mechanical strength to endure its harsh operating conditions.A tundish stopper rod for continuous casting according to the present invention comprises:(a) a stopper rod for regulating the flow rate of molten metal being supported by a spindle and being made of a refractory material, and(b) a nut for attaching the stopper rod onto the spindle, the nut being made of an engineering ceramic material and being embedded in a body of the stopper rod.

Abstract: A method for supplying molten metal alloy for producing thin amorphous metal wire or thin amorphous metal strip by liquid quenching and solidification on a moving cooling substrate controls the flow of molten metal from a ladle into a tundish. The ladle has a long nozzle with an interior passage for providing flow of molten metal alloy into the tundish. The ladle stopper has a distal end region received by the interior passage of the long nozzle. Control of the overlap between the distal end region of the ladle stopper received in the long nozzle during molten alloy flow and control of the sectional flow area provided in the long nozzle interior passage controls the flow quantity of molten alloy from the ladle into the tundish.

Abstract: An arrangement for connecting an elongated stopper rod made of a refractory material for a metallurgical vessel to a lifting device for the stopper rod is provided. The arrangement includes a stopper rod having an upper front side and an internal longitudinal recess extending therefrom, a support having one end for engaging the lifting device an another end for engaging the stopper rod in the internal longitudinal recess. The stopper rod includes a housing that laterally widens a portion of the longitudinal recess, the housing having an upper boundary surface transverse to the longitudinal axis of the stopper rod and having side walls that taper from the upper boundary surface into the longitudinal recess.

Abstract: The arrangement (100) has a retaining rod (10) that is divided into an upper part (18) that is capable of being attached to a lifting device and a lower part (1) that projects into a plugging rod (2), that comprises a rapid connection device for the firm gas-tight connection of the lower part (1) to the upper part (18) whereby this permits easy exchange of a worn plugging rod. The region of the lower part (1) of the retaining rod (10) that projects into the plugging rod (2) is provided with means for engagement (3, 4, 35) that, as a result of communal isostatic compression engage with the ceramic material of the plugging rod (2) and generate a gas-tight, non-detachable connection of the lower part (1) of the retaining rod (10) to the plugging rod (2).

Abstract: In a device for controlling a flow of metal from a casting vessel into a casting mould, the inflow of metal is to be controlled by means of a stopper, which may be lifted and lowered according to a preset program and/or by means of a bath-level measuring device. In order to prevent any manual operation of a control lever for the stopper, a lifting rod for the stopper is disposed in a module box together with a vertical guide and a computer-controlled electromechanical drive for the lifting rod. The module box is exchangeably fastened to the casting vessel by clamping elements. Before casting begins, a drive motor for the stopper (13) is to be connected by means of electric plug-and-socket connections to a control cabinet. From the start of casting, the stopper movement is controllable exclusively by means of the electric drive.

Abstract: In a device for controlling a plug (5) of a metallurgical vessel (1), in particular a distributing launder of a continuous casting installation, with a plug (5), which can be raised and lowered and which is supported in a support frame which is movable relative to the metallurgical vessel (1), the support frame for the plug (5), which can be raised and lowered, is supported outside of the metallurgical vessel (1) displaceable in a direction crosswise to the lifting direction of the plug (5) and can be releasably locked together with the metallurgical vessel. By means of this a simple separation of the plug mechanism (9) and the metallurgical vessel (1) is possible without operational elaboration and an exchange of the metallurgical vessel (1), for example, is made possible without having to dismantle the entire plug mechanism (5, 9).

Abstract: A stopper drive mechanism is removably mounted on a molten metal vessel having a discharge opening and is adapted to move a stopper into and out of closing engagement with the discharge opening. A piston and cylinder unit of the stopper drive mechanism is operably connected with the stopper and has a valve unit connected thereto for controlling the piston and cylinder unit. The piston and cylinder unit comprises a cylinder that defines a working chamber with a piston slidably disposed therein. The piston has the same effective working area on opposite sides thereof. The valve unit comprises a control valve for controlling the flow of hydraulic fluid to and from the opposite sides of the piston and a bypass valve that is adapted to selectively communicate opposite sides of the piston with each other for manual movement of the stopper.