FR2779673A1 - Dummy for a continuous casting installation with a mold - Google Patents

Abstract

A dummy (4), for a continuous casting installation has a mold (3) in the form of a tube which is filled with molten metal (2) and which is initially filled by the head (9) of the dummy (4) The head (9) of the dummy (4) comprises a chamber (92) emerging in a upper face (930) of a front part (93) of the head. The walls of this chamber incorporate some claws (940) which can move transversely between an advanced position in which the claws are engaged in the chamber and a retired position in which the claws entirely liberate the volume of the chamber.

Description

Mannequin of a continuous casting plant in an ingot mold.

  The invention relates to a mannequin of a

  continuous casting installation in an ingot mold.

  Part of an installation of this type, shown diagrammatically in FIG. 1, conventionally comprises a distributor 1 which supplies metal in

  fusion, such as steel, to an ingot mold 3.

  The ingot mold is a tube which has a defined section, generally of square shape, making it possible to obtain, by molding, bars of the cast material, of great length.

and in one piece.

  Before starting a casting, the head of a dummy is introduced into the mold to block it. The dummy is a beam which can slide in the mold, so as to allow, at the start of the casting, the extraction of the metal which comes to solidify in contact with the walls of the mold and the head of the dummy. The dummy is conventionally driven by motorized drive rollers R which exert on it a tensile force. As soon as the drive rollers are able to drive the molded bar, the manikin is then

detached from the bar.

  To ensure the extraction of the solidified metal, the head of the manikin is provided with anchoring means on which the solidified metal can come to hang, in order to transmit to it the tensile force exerted on

the model.

  A first anchoring means is known, shown diagrammatically in FIG. 2, which is generally used in continuous casting installations in curves. The head of the mannequin 4 comprises a hook 5 constituting an insert which will be molded in the solidified metal. A stall torque, marked by the arrow F1, is exerted on the manikin to release the hook

solidified metal.

  Other anchoring means are also known, shown in FIGS. 3 and 4, which are generally used in vertical continuous casting installations. As shown in Figure 3, a tapered conical hole 6 is made in the head of the dummy 3. The molten metal 2 enters the hole 6 to form a threaded end of solidified metal, which ensures the attachment of solidified metal with the manikin thread. To take down the mannequin, one exercises on him

  a loosening torque marked by arrow F2.

  The other anchoring means (see FIG. 4) is a nail 7, one of its ends of which is locked onto the head of the manikin in a manner known per se, such as by a needle screw 8, and the other end of the nail is provided with a head which is found molded in the solidified metal. To take down the mannequin, we

  unlocks the needle screw 8 to release the nail 7.

  The anchoring systems presented do not ensure reliable anchoring of the solidified metal with the head of the manikin. Indeed, the peripheral layer of metal, in contact with the head of the dummy and the walls of the mold, somehow forms a skin of solidified metal whose heart is not sufficiently cooled and, therefore, is still liquid . The attachment can be fragile if the metal is not solidified enough to ensure a correct grip and when the tensile force is exerted on the dummy, this can cause a tearing of the attachment. This may result in a flow of the core, still liquid, of the metal poured into the continuous casting installation, which is dangerous and harmful since the preparations for casting

are to be redone.

  This is why we use M scrap, such as steel bar ends, to accelerate the cooling of the molten metal at the head of the manikin. However, the scrap necessarily causes local pollution of the cast metal. This induces an increase in the rate of waste from the casting bar, in particular because the part must be removed by cutting.

polluted metal.

  The manipulations to quickly unhook the mannequin are not simple to perform. In addition, the systematic use of grapeshot generates a

additional cost.

  The invention aims to eliminate, or at least limit, the problems mentioned above and aims to improve the reliability of the anchoring of the head of the

  mannequin with solidified metal.

  With these objectives in view, the invention relates to a dummy of a continuous casting installation in an ingot mold, the ingot mold being a tube into which a molten metal is poured and which is capped, at the start of casting, by the head of the manikin, characterized in that the head of the manikin comprises a chamber opening into an upper face of a front part of the head, the walls of the chamber comprising claws which are movable transversely between an advanced position in which the claws are engaged in the chamber and a withdrawn position in which the claws

  completely free up the volume of the room.

  Preferably, the dummy comprises a heat accumulator extending downward from the front part, the heat accumulator being made of a mass of a material with high thermal conductivity for evacuating and accumulating, away from the front part, the heat flow

  generated during the solidification of the molten metal.

  Furthermore, the upper face of the front part is preferably wavy to increase,

  in a longitudinal direction, its contact surface.

  The invention therefore makes it possible to increase the heat exchange between the molten metal and the head of the dummy by increasing the contact surfaces. This arrangement considerably accelerates the cooling and solidification of the molten metal, and therefore eliminates the systematic use of scrap metal. The heat accumulator can for example be produced in a copper or alloy block.

copper.

  In order to avoid deterioration of the front part of the dummy's head, mainly caused by the high temperature of the molten metal in contact with the front part, the heat accumulator is massive, i.e. it can rapidly distribute the heat flow towards the interior of the manikin from the front. This arrangement makes it possible to maintain the temperature of the front part

  at an acceptable temperature level.

  According to a preferred embodiment, the walls of the chamber consist of two jaws which are mounted articulated on the manikin around parallel pivot axes, between an open position and a closed position in which the jaws are applied one against the other. the other, and in which fingerprints are made which jointly form the chamber. Preferably, in this embodiment, the upper face of the jaws is curved to increase, in a transverse direction, its contact surface and, moreover, the head of the mannequin comprises a pin forming a heat sink for removing the

  calories of molten metal contained in the chamber.

  The head of the mannequin forms a mold which is produced in two parts, that is to say by the two articulated jaws, which are held in contact with each other by latches. The joint plane of the mold is a plane of symmetry for the jaws. The impressions, which jointly form the chamber, are made in

each of the jaws.

  At the start of casting, the jaws are in the closed position and the mold cavity is filled with molten metal which is sufficiently cooled by the front of the head and by the spindle to ensure rapid solidification. The front part of the head, the bottom of the chamber and the pin can be made of copper or a copper alloy. The extraction of the casting bar is ensured by the claws. To unhook the manikin, the locks are unlocked, manually or by automatic control means,

  to allow the tilting of the two jaws.

  In addition, the head of the manikin may include temperature measurement probes. The temperature probes, such as for example a thermocouple, will be arranged and arranged to allow a measurement of the temperature of the solidified metal and the degree of solidification of the cast metal, for example at the level of the upper face of the mannequin and inside bedroom. This arrangement will make it possible to monitor the temperature of the manikin's head and therefore to be able to determine the appropriate moment from which

  will be able to exert the tractive effort on the dummy.

  Other characteristics and advantages will appear

  in the description which will be given as an example

  of a dummy of a continuous casting installation in

  ingot mold according to the invention.

  Reference will be made to the appended drawings in which: - Figure 1 is a front view of part of a continuous casting installation, - Figures 2 to 4 illustrate different examples of means for anchoring dummies depending on the state of the known technique, - Figure 5 is a schematic cut-away perspective view of the head of the mannequin according to the invention, - Figure 6 is a right view of the head of the mannequin of Figure 4, - Figure 7 is a top view of the head of the mannequin of Figure 4, - Figure 8 is a front sectional view of the head of the mannequin of Figure 4, showing the jaws in the extreme positions of use, that is say the closed position and the open position which is indicated by a dotted line, - Figures 9 and 10 are front views of the head of the dummy of Figure 4, showing the latches, - Figure 11 is a view showing an alternative embodiment of the locking of the jaws, - the figures 12 and 14 are schematic views of alternative embodiments of the manikin head, FIG. 13 is a schematic view of the manikin head, showing the use of measurement probes

of the temperature.

  We will not return here to the description of

  Figures 1 to 4 (schematically showing part of a continuous casting installation and various known anchoring systems) which was made in the introduction during

  the presentation of the known technique.

  Figure 5 shows the interior of the mold 3 of the continuous casting installation, in a longitudinal section. Conventionally, the ingot mold is a tube into which a molten metal 2 is poured in order to obtain by molding steel bars which will then be cut to obtain billets. Before starting a casting, the mold is obstructed by the head 9 of the dummy 3, the latter being slidably mounted in the ingot mold to subsequently ensure the extraction of the

solidified metal.

  The head of the mannequin has two jaws 90 which constitute the two parts of a mold and which are made for the most part in refractory stainless steel, such as that commonly designated Z8CN25-20. The steel used ensures the mechanical strength of the jaws, particularly by resisting deformation at high temperatures, and preventing oxidation. The joint plane of the mold, designated P, is a plane of symmetry for the two jaws. Each jaw is pivotally mounted, by one of its ends, on the mannequin around a pivot axis A constituted by a cylindrical shaft 91. As shown more precisely in Figures 9 and 10, the two jaws 90 can tilt around pivot axes between a closed position, in which the two jaws are applied against each other and held in this position by latches 10, and an open position. To allow the tilting of the two jaws during opening, the lateral edges 40 of the

dummy 4 are chamfered.

  The joint of each jaw is made as a hinge (see Figure 6). This arrangement makes it possible to have a large number of shaft sections, marked Sc, on which the shear stresses are exerted, so as to distribute the shear stress uniformly on the shaft 91 during the application of the tensile force Ft on the dummy. A chamber 92, formed of two half-chambers which are produced in each jaw 90 and which jointly constitute said chamber when the two jaws are in the closed position, constitutes the imprint of the mold, of a generally paralelepipedal shape. The chamber opens into the upper face 930 of the front part 93 of each jaw (see FIG. 7). Claws 94, allowing the transmission of the tensile force to the solidified metal, are formed by projections extending from the walls of the chamber. At the start of the casting, the chamber is filled with molten metal in order to make a connection between the head of the dummy and the metal which comes to solidify on contact with it (see Figure 8). As this figure also shows, to ensure the release of the end of the bar which has just been cast, in order to allow the jaws to open, the upper face 930 of the front part 93, one face 920 of the bottom of the the room, as well as walls thereof, are

curved.

  To accelerate the solidification of the molten metal in contact with the head of the dummy, the front part 93 of the head is a layer of a material with high thermal conductivity, such as for example copper or

  a copper alloy containing chromium and zirconium.

  Furthermore, the bottom of the chamber is also made of a material with high thermal conductivity, for example

  example identical to that of the front part.

  The upper face of the front part of each jaw is wavy so as to increase, in a longitudinal direction (indicated by the arrow L at the bottom of FIG. 5), the contact surface with the molten metal, in order to promote exchanges thermal. In addition, the upper face of each jaw is curved, in a transverse direction (marked by the arrow T at the bottom of FIG. 5) to also increase the contact surface and ensure the detachment of the head

of the mannequin.

  The front portion 93 of each jaw 90 and the bottom of the chamber 92 are for example attached prefabricated elements which are fixed to the jaws, in a manner known per se. By way of example, a tenon-mortise type fastening system may be used, as shown diagrammatically in FIG. 8, in which tenons forming a male part, which are produced on the prefabricated elements, can be fitted in mortises of a given width, forming a female part, made in the jaws. To ensure the mechanical connection of the assembly, it is possible to use a hot-fitting technique which consists in expanding the female part by heating it then in engaging the male part therein, the latter being of a width substantially greater than that of the male part and, as soon as the assembly is carried out, to allow the assembly to cool, so that a compressive force is exerted on the lateral flanks of the tenons during the cooling of the mortise. The adjustment between the different elements will be determined so as to avoid dismantling of the assembly described above, during normal use and, mainly, under the

  important temperatures of use.

  In the event of excessive wear, the front part of each jaw and the bottom of the chamber can be dismantled to replace them or reload, i.e. depositing successive layers of solder on the parts of the jaws. jaws in contact with the molten metal, then machine these in order to shape them. The thickness of the front and bottom of the chamber must be sufficient, so as to form a massive heat accumulator

  in a material with high thermal conductivity.

  Specifically to the invention, the heat given off by the molten metal does not accumulate at the level of the upper face of the front part of each jaw, in order to avoid deterioration and deformation of the material directly in contact with the molten metal. The heat flow tends to diffuse inside the massive front part, as well as in the bottom. This arrangement keeps the temperature of the front part at a level of

acceptable temperature.

  Furthermore, also specifically to the invention, a pin 11 of cylindrical shape is used which constitutes a heat sink making it possible to effectively improve the evacuation of calories, in order to solidify the molten metal even more quickly.

  which is poured into the chamber, at the start of the casting.

  To promote heat exchange, the end of the spindle is in the form of a half-sphere, in order to increase the contact surface. The pin 11 is made of a material with high thermal conductivity, such as for example copper or a copper alloy. It should be noted that a pin similar to that which has just been described can also be applied to the mannequins of the prior art. Indeed, the pin can be directly incorporated into the end of a mannequin known from the prior art, for example in the form of a block of a material with high thermal conductivity, such as for example copper or copper alloy, so as to accelerate the

  cooling of molten metal.

  When the two jaws are applied against each other, the joint plane is sufficiently leaktight to prevent any leakage of molten metal, so as to avoid the resulting disturbances, and in particular to prevent any weld liable to form on moving parts and which would be very harmful, for example, when opening the jaws. It should be noted that the axes of articulation of the jaws, as shown in the drawings, are located at a distance from the joint plane and are protected against any projection of molten metal, which makes it possible to avoid the problem.

mentioned above.

  As shown in Figures 9 and 10, two locks 10 are used which are located laterally on each side of the head. The locks are inserted into housings 95 which are produced in the jaws and are mounted there pivoting, by one of their ends, about a pivot axis B. The unlocking control of each lock is manual, that is that is to say that an appropriate tool is used which can engage in a notch 101 made in the lock, in order to exert an effort therein to rotate said lock. The other end of the lock has a hook 102 which engages in the locking position with a first shoulder 951 produced in the edge of the housing. Said end of the lock also includes a stop 103 which cooperates with a second shoulder 952, produced in the edge of the housing, when the two jaws open to limit the angular movement (see figure). The closing and opening of the two jaws can also be carried out automatically, that is to say using control means, such as those shown by way of example in FIG. 11. For this, one can use the cam-shaped end 130 of a rod which can slide axially, in the direction of the dummy, in a housing produced at the separation between the two jaws. By sliding, the cam can come into contact with the walls of the housing, which ensures the spacing or the approximation of the jaws according to the direction of movement of the cam

(arrows F4).

  Figure 12 shows an alternative embodiment of the shape of the chamber 92. It can therefore have a funnel shape whose walls are corrugated to ensure the connection between the solidified metal the head of the mannequin and, moreover, increase the surfaces of contact. Figure 14 shows a simplified alternative embodiment of the manikin head. The chamber 92 is produced directly in the form of a hole in the front part of the end of the manikin. The upper face 930 of the front part 93 remains wavy and curved, to perform the functions described above, and screws 940 pass substantially radially through the wall of the chamber to engage inside the latter. The screws constitute the claws for transmitting the tensile force exerted on the dummy to the solidified metal. To unhook the manikin, the screws are removed so as to completely free up the volume of the chamber. Pin 11 is also used to solidify the molten metal poured

in the bedroom.

  In order to monitor the temperature of the head of the manikin and the degree of solidification of the molten metal, to determine for example the appropriate moment to apply the tensile force to the manikin, measurement probes may be used of the

  temperature, designated ST, such as thermocouples.

  It should be noted that measurement probes similar to those described in the present invention may be used in mannequins comprising a heat accumulator, that is to say a massive part in a material with high thermal conductivity, such as

  for example copper or copper alloy.

Claims (10)

  1. Mannequin (4) of a continuous casting installation in an ingot mold (3), the ingot mold (3) being a tube into which a molten metal (2) is poured and which is blocked, at the start of casting, by the head (9) of the mannequin (4), characterized in that the head of the mannequin comprises a chamber (92) opening into an upper face (930) of a front part (93) of the head, the walls of the chamber comprising claws (94, 940) which are movable transversely between an advanced position in which the claws are engaged in the chamber and a withdrawn position in which the claws   completely free up the volume of the room.   2. Mannequin according to claim 1, characterized in that it comprises a heat accumulator (11) extending downward from the front part, the heat accumulator being made of a mass of a material with high thermal conductivity to evacuate and accumulate, away from the front part (93), the heat flow generated during the solidification of molten metal.   3. Mannequin according to claim 1, characterized in that the upper face (930) of the front part is corrugated to increase, in a   longitudinal direction (D), its contact surface.   4. Mannequin according to claim 1, characterized in that the walls of the chamber consist of two jaws (90) which are mounted articulated on the mannequin around pivot axes (91) parallel, between an open position and a position closed in which the jaws are pressed against each other, and in which impressions are made jointly forming the chamber (92). 5. Mannequin according to claim 1, characterized in that control means (13, 131)   are provided to rotate the jaws.   6. Mannequin according to claim 4, characterized in that the claws (94) are formed by projections extending from the walls of the chamber. 7. Mannequin according to claim 4, characterized in that the upper face (930) of the jaws is curved to increase, in one direction   transverse (T), its contact surface.   8. Mannequin according to claim 2, characterized in that it comprises a pin (11) forming a heat sink for removing heat from the metal by   fusion (2) contained in the chamber (92).   9. Mannequin according to claim 4, characterized in that the jaws (90) are held in the closed position by latches (10) which are located on either side of the head and which are pivotally mounted   in housings (95) made in the jaws (90).   10. Mannequin according to claim 1, characterized in that the head (9) comprises probes temperature measurement (ST).