EP0018350B1 - Continuous-casting plant, especially for producing slabs - Google Patents

Description

The invention relates to a continuous caster, in particular for producing slabs with a coolable continuous mold, a straight or curved strand guide for transporting, cooling and possibly deflecting the strand, which has a guide frame into which two mutually opposing rows of walking bars are installed each of which can be periodically adjusted against the strand by means of a drive device, can be moved by a predetermined transport step, can be lifted off the strand and can be returned to its starting position, the movement cycle of the walking bars belonging to one group being approximately one compared to the movement cycle of the walking bars belonging to another group half period is offset, and in the case of an arcuate strand guide with an adjoining straightening device with drivable straightening device arranged in the frame with drivable straightening tools arranged in the frame for straightening the S tranges and all walking bars are designed as transverse bars running transversely to the longitudinal median plane of the strand and in pairs opposite one another with respect to the strand (DE-B-1 608 352).

An essential and very costly part of every continuous sheet caster is the strand guide, in and with which the strand which essentially emerges from the mold is deflected and cooled. Straight or arcuate strand guides with rollers arranged in a row on both sides of the strand are known. Each row contains a significant number of rollers, which are not only mechanically but also thermally stressed, which is very high and unfavorably, and are therefore far less stable than might be expected. Since the strand shell is supported by each roller only along a very narrow area strip, adjacent rollers in each row must be as close as possible to one another. Therefore, the space available for accommodating the device for spraying cooling water is very narrow and is disadvantageously designed, so that only a central surface zone of the strand shell section between adjacent rolls can be effectively cooled, since the rolls themselves do not contribute to the cooling. The strand shell is not supported in these sections, can therefore bulge and is often bent out and back as it passes through the rows of rollers, which adversely affects the structure of the solidified strand.

Blocks of very different cross-sectional formats are required by the processing industry. The production of such blocks by cutting a strand to the desired cross section means converting an existing continuous casting plant to this cross section. In order to save this expensive work and the associated downtimes, the company has started to cut the blocks out of slabs, which should be as wide as possible for economic reasons, but whose broad sides must be flat and parallel. For example, blocks formed from a longitudinally divided, 2700 mm wide slab can no longer be properly rolled out if they are about 1.5 mm thicker on one of their narrow sides than on the other. The slab width that can be achieved purely by casting technology cannot currently be used, because the curvature of the broad slab sides is determined by the deflection of the rolls in the case of strand guides equipped with rolls. In fact, the slab widths that can be used are governed by the permissible deflections of the rolls, the rule of thumb being that the roll diameters must change in the same ratio as the slab widths. This results in the currently valid limit for the slab widths, beyond which the rollers become too heavy and the distances between the support points of the strand shell are too great. While it has been suggested not only to support or divide the rollers at their ends but also between them, these measures have not proven successful.

Continuous-arch casting systems have also been proposed and built, the strand support of which is equipped with walking beams arranged on both sides of the strand. These walking beams are designed as longitudinal beams curved in accordance with the shape of the continuous arch, with two broad groups of such beams opposing each broad continuous surface and between two adjacent beams of one group and one of the other associated beams. Each bar group can be adjusted against the strand, can be moved in the longitudinal direction in the engaged state, can be lifted off the strand and can be returned to the starting position in the raised state, and the movement sequences of the two longitudinal bar groups are shifted in phase by essentially half a period. In systems of this type, the support of the strand and its cooling are improved because the coolable longitudinal beams lie flat against the strand shell, but the weight and, in particular, the masses to be moved are large in the case of strand supports for wide slabs.

This also applies if the individual longitudinal beams do not extend over the entire length of the strand arch, which can be 15 m or more, for example, in the case of strands of large cross section, but rather in the longitudinal direction are divided, so that the entire strand guide is made up of several contiguous sections. The reduction in the total mass to be moved and its distribution that can be achieved in this way cannot contribute to reducing the difficulties associated with the drive, which are due to the need to arrange the drive elements necessary for each beam above or below the strand and to expose its heat radiation. The entire drive arrangement is therefore difficult to monitor, inaccessible and subject to high temperatures during operation, which is why relatively minor defects can only be remedied after the system has been switched off and cooled down. In addition, the removal and installation of the middle walking beam located between the two outermost and subject to greater wear is a difficult and time-consuming work. In addition, despite the division of the mass to be moved, the practically usable frequencies of the beam movement are restricted upwards.

In the known continuous casting plants with subdivided longitudinal beams, the entire ferrostatic pressure of the strand must also be absorbed by the drive shaft of the longitudinal beams. With a slab width of z. B. 2 m is the span of the shaft between its bearings at least 2.5 to 2.7 m at a ferrostatic pressure of about 25 to 30 t. It can be seen that the drive shafts and their bearings must be dimensioned extremely heavy under these circumstances. A transition to slab widths of 3 to 4 m, corresponding to shaft spans of 4 to 5 m, is hardly conceivable, since it would lead to extremely heavy structures with the corresponding effort.

Continuous casting plants with a strand guide of one or the other structure are in operation today. Up to now, however, the strand guides equipped with walking beams have not been able to achieve any decisive advantage over those equipped with rollers; rather, roller strand guides are still built today. Currently, the maximum widths of slabs with sufficiently precisely parallel wide areas are 180 to 220 cm; However, in order to cope with them, a material effort is required which is due to the mechanical and not the metallurgical side. The casting of 300 to 400 cm, perhaps also 500 cm wide slabs is not a problem in terms of casting technology, which is not manageable and cannot be solved at relatively low cost. The crux lies in the strand guides, which, particularly as far as roller strand guides are concerned, entail difficulties dictated by the concept, which stand in the way of the production of slabs with the aforementioned larger widths and parallel wide surfaces.

The aim of the invention is a continuous caster with a strand guide, which allows the casting of slabs with a width which is considerably greater than the usual, which is lighter overall than the known one and in which the mass to be moved is broken down into a large number of comparatively small masses. This goal can be achieved with a continuous caster of the structure outlined at the beginning, in which, according to the invention, each crossbeam is connected to the one end of at least one plunger and is supported by the plunger or plungers against the guide frame, the plungers for starting and lifting as well as for the transport and return movement of the crossbar are drivable and preferably also the tools of the straightening device are designed as crossbars supported with punches against the scaffold or a device frame and can be adjusted or lifted off the strand with the aid of the punches.

The weight of the strand guides of continuous casting plants according to the invention is considerably less than the weight of comparable walking beam guides with longitudinal bars, the weight saving becoming noticeable with slab widths of approximately 200 cm and increasing considerably and progressively with increasing slab width. The drive devices or their elements can be laid on both sides, as well as simple and reliable, they are outside the high temperature range and can be screwed on in their entirety. In contrast to the known systems with walking beam guidance, the ferrostatic forces are transmitted from the walking beams directly to the guide frame in the system according to the invention, so that the actual drive does not have to be dimensioned excessively heavy. The crossbeams can be relatively narrow and be arranged at intervals which readily allow the installation of devices for effectively cooling the strand with sprayed-on coolant, and the division into a large number of low-mass parts makes it possible to significantly reduce the sequence frequency of the movement cycles compared to the hitherto usual ones to increase.

The strand usually enters the strand guide at a temperature of at least 1000 ° C and out of it at a temperature of 500 ° C. All crossbars rest against the strand along a surface strip, within which the temperature drop in the longitudinal direction is small, for. B. is 0.3 ° C / cm. There is therefore no danger that the crossbeams will warp as a result of temperature differences.

It is very advantageous to arrange the two crossbeams of a pair of crossbeams or a plurality of consecutive crossbeam pairs of the strand guide and / or the straightening device together with the stamps in a common frame and with this to form a detachably attachable to the guide frame unit, preferably all units containing the same number of crossbeam pairs are identical to one another. The installation and removal or replacement of crossbars is then particularly easy and can be done from the side. Each crossbar can be supported with two or more, but most simply by means of a single plunger, which advantageously extends essentially over the entire length of the bar. It is advisable if at least that crossbeam which is the mold first can be driven individually; it may even be advisable to drive all crossbars individually. From the respective conditions, e.g. B. from the metal to be cast and the cross section of the strand depends on how far it is possible to drive a number of consecutive crossbars together to simplify the strand management, in particular to combine two adjacent or three consecutive to a drive group in which a crossbar is directly driven is and with this the others are coupled to drive movement. In many cases, a combination is recommended, in which the crossbar, which is the mold first, and a number of the bars following it individually and each of the remaining crossbars several, successive, e.g. B. two or three can be driven together. The solidified strand shell is still thin in the vicinity of the mold and can be expanded under the influence of the ferrostatic pressure. Within this range, the strand is always supported over a crossbar width at points spaced apart from one another by a little more than a crossbar width and can bulge between the relatively dense support points. The bulges, which are not very important in themselves and which are not very significant in themselves, and which develop relatively slowly, can, however, be intercepted if the crossbeams are moved with correspondingly high repetition frequencies, so that the strand shell is only slightly bent back and forth, which is very is desired.

The forces to be exerted or taken up by the crossbeams can e.g. B. generated or collected with hydraulic cylinders that are reciprocable along the strand guide. It is more advantageous, however, to design all the stamps supporting a crossbar as levers, one end of which is attached to the crossbar, preferably articulated, and the other ends of which are pivotally connected to the guide frame or the frame, because the crossbar is then more flexible and conforms to the shape of the Can adjust strand area automatically. The pivot point of the lever or the lever of at least one crossbeam of some, but preferably all, of the crossbeam pairs is arranged on a bolt loaded with a force and displaceable against this force, in particular on the piston rod of a hydraulic cylinder or the like. This variant allows the compressive forces acting on the strand to be limited at the top because the crossbeam can deflect. In addition, the bolt can be adjustably fastened to the guide frame or the frame so that it is possible to adjust all the beams individually and relative to one another and to adapt the course of the arc determined by the strand guide to a predetermined desired shape precisely and conveniently. This target shape is not definitively determined once and for all, but is entirely changeable, it being possible, in particular and also subsequently, to set the arch shape which has been found to be best suited to the entire production process. It should also be mentioned that the design of the crossbeams is largely independent of the desired arch shape, for example, crossbeams designed for circular arch guides can also be easily installed in wicker arch guides and vice versa, which is not permitted with longitudinal walking beams because they must be precisely adapted to the strand curvature and also require a curvature that is invariable in the longitudinal direction of the strand. In a preferred embodiment, the one or more crossbar supporting levers are designed as toggle levers and both lever arms of at least one toggle lever can be driven, the toggle lever arm on the beam side near the articulation point on the crossbars, the other toggle arm each having a link guide in the vicinity of the knee joint and in each link slot the pin engages a stationary, drivable crank.

However, it is also possible to design the lever or arms supporting a crossbar as a pivot lever and to drive at least one pivot lever for a reciprocating movement, e.g. B. with a link guide for the pin of a stationary drivable crank, the end of the pivot lever remote from the strand is preferably movable by means of a pressure medium cylinder against the strand and away from it.

The cooling of the strand is straightforward in the continuous casting plants according to the invention, because the crossbars lying flat against the strand bring about extensive heat removal if they themselves are adequately cooled. For this purpose, the strand-side end of all a crossbar supporting lever with a cylinder, in particular a hollow cylinder or a pan connected and formed on the crossbar a surface contacting this pan or a cylinder, in particular hollow cylinder and in the coolable on the inside of the hollow cylinder z. B. a device for spraying coolant on the cylinder wall. Such cooling devices effect not only sufficient cooling of the crossbeam, but also of the socket joint connection with the lever and the latter. In many cases, spraying the strand with cooling water can be dispensed with and e.g. B. the crossbars are cooled, in others, especially when casting strands with considerable cross sections, this type of effective cooling is indicated. Crossbars have proven to be very effective, which have a number of cells separated by web walls, which are open on their front side facing the strand and open on the rear side, or on their rear side each with a rear wall which is provided with a passage opening, whereby nozzles for spraying the strand surface through the cells are attached to the rear of the bar. The crossbeam touching the strand is immobile in relation to it, so there is no sliding friction and forces originating from it and which stress the solidified strand jacket.

An important part of every continuous caster is a cold strand, which consists of a number of articulated links in a continuous caster.

In the known systems, it was necessary to use relatively long cold strands, which are accordingly difficult to handle. In continuous casting plants constructed in accordance with the invention, the strand guide contains many elements which follow one another at relatively short intervals and are provided with contact surfaces, namely the crossbars. A proper adaptation between crossbars and strand links makes it possible to arrive at cold strands which are satisfactory in every respect and consist of relatively few hinged links and are therefore relatively short, light and therefore easy to manipulate. In such cold strands, the links are designed as cross bars approximately the same width as the cross bars; the crossbars have at one end or at both of them a section provided with a longitudinal profile and on the strand guide on one side or on both sides an extension is formed which interacts with a bar section and is provided with a profile complementary to its profile. In the case of strand guides with an arc radius of approximately 10 m, such a cold strand need not be longer than 2 to 3 m and can be handled very easily by means of the overhead crane.

The invention is explained below with reference to exemplary embodiments and the drawing. 1 a and 1 b show an arc continuous casting installation according to the invention in a longitudinal section, FIG. 2 shows a frame, FIG. 3 shows a section along line 111-111 of FIG. 2, FIG. 4 shows a toggle lever drive in four phases of movement, Fig. 5 a group of three jointly drivable toggle levers, Fig. 6 a swivel lever including drive, Fig. 7 a variant of a swivel lever, Fig. 3 and a sectional view of an embodiment of a crossbeam and Fig. 10 a strand guide with inserted cold strand.

The continuous sheet caster shown in FIGS. 1b and 1b has a coolable continuous mold 1 which is fastened to a horizontal support 2 connected to stands 3. Below the mold, a cooling section 4 is arranged, in which the extruded strand 5 is guided along bars which cross each other in a lattice manner and the spray devices (not shown), e.g. B. contains nozzles or nozzle pipes for spraying a coolant through the window onto the strand surface. The cooling section is followed by a strand guide, to which a number of crossbeams supported against an arcuate guide frame 6 belong and which is intended to guide the strand leaving the cooling section 4 in a substantially vertical direction along an arc in the horizontal direction. The crossbeams are arranged in an upper row which faces the upper, concave of the two curved strand surfaces, and in a lower row which lies on the side of the lower, convex strand surface. All crossbars are assigned to one another to the extent that each bar 7 in the upper row is opposite a bar 8 in the lower row. In the embodiment in question, the individual pairs of crossbeams are each housed in a frame 9 (FIGS. 2 and 3) and each beam 7, 8 is connected to a single stamp extending over all or a substantial part of its length, which acts as a toggle lever 70 or 80 is formed. The use of a single stamp is not mandatory, but in most cases it is much simpler than the possible support with two or more stamps. The crossbar 7 or 8 is articulated to the free end of the toggle arm 71 or 81 on the strand side, whereas the free end of the other toggle arm 72 or 82 is articulated to a cross member 90, 92 of the frame. The frame are placed on the arcuate guide frame 6 and detachably fastened to it by means of screw bolts or the like, so that they can be individually assembled or replaced, and simply, from the side, without any special work and without the aid of devices other than those already available Cranes of the plant. Another advantage is the simple and weight-saving construction. The guide frame can be constructed from simple arch supports and is not loaded with any forces other than the weight of the units consisting of frame, beam and their drive levers and the weight of the strand, whereas all the forces required for the strand transport or their reactions are from the frame 9 are included. These are essentially tensile forces to be absorbed by the longitudinal frame members.

The frame 9 consists of two longitudinal spars 91 which are connected at their upper ends to the cross spar 90 and at their other ends to the cross spar 92, which is provided with foot plates which can be screwed onto the frame. Each of the two crossbeams 7 and 8 is articulated to the adjacent toggle lever arm 71 and 81 by means of a socket joint, which consists of a circular cylindrical socket 73 and 83 formed on the beam and extending over its entire length, and from a hollow cylinder 74 that contacts the surface thereof or 84, who sits at the free arm end. A nozzle tube can be arranged inside the hollow cylinder, with which cooling liquid can be sprayed against the side of the cylinder inner wall opposite the pan. If the crossbeams are made of a material with good thermal conductivity, this cooling can be sufficient. A further embodiment of a crossbar can be seen in FIGS. 8 and 9. This crossbar 100 has a number of cells 101 with axes normal to the string broadside. The cells are laterally delimited by web walls 102 and separated from one another. In any case, the cells are open on their front surface facing the strand, they are open on the back (FIG. 8) or partially covered by a rear wall 103 (FIG. 9). This rear wall is provided with a passage opening 104 in the area of each cell. Each rear cell opening or passage opening is juxtaposed with a nozzle 105, from which cooling liquid can be sprayed through the cell onto the strand surface. The nozzles are connected to the crossbar and are located, for example, on feed pipes that extend between two end walls 106 of the beam. With such crossbeams a completely sufficient support and at the same time a very effective cooling of the strand can be achieved.

The toggle 70, 80 and accordingly their z. B. a pivot joint, connected arms 71, 72 and 81, 82 can be formed as extending over the entire length of the cross beams 7 and 8, stiffened with transverse walls, and are pivotally attached with their outer ends. At the in F i g. In the embodiment shown in FIG. 2, the lower toggle arm 82 of the lower toggle lever is rotatable about pivot bearing 64 which is stationary relative to the cross member 92 of the frame, whereas the pivot points of the arm 72 of the other toggle lever on the cross member 90 of the frame are adjustable in the normal direction to the strand. A hydraulic cylinder 93 is placed on each of the cross bars near its two ends, the piston rods of the two cylinders are connected to a cross bar and this is pivotally connected to the end of the toggle arm 72.

The upper toggle lever 70 is therefore not connected to the frame at a position which is immovable relative to it, but the pivoting point of its arm 72 can be shifted normally to the strand also during the operation of the system, specifically against the force exerted by the hydraulic cylinder and thus adjustable. As shown in FIG. 3, the lower toggle lever 80 or its arm 82 can also be connected to the frame via hydraulic cylinders 93.

It goes without saying that not only a pair of crossbeams together with their toggle levers or general stamps can be connected to a frame to form a unit. Rather, two, three (Fig. 5) or more adjacent crossbeam pairs with their levers or stamps can be mounted in a common frame and combined to form a unit that can be installed or removed as a whole.

The task of deflecting and transporting the strand by means of the strand guide, which incidentally is less about pulling out the strand than braking it, requires an orderly transport movement of the crossbeams. The strand must always be held so that the movement determined by crossbeams can be impressed on it. For this purpose, the crossbar pairs are kinematically combined into groups and the movements of the bars of such a group are offset by practically half a period compared to the movements of the bars of another group, i. H. the bars of one group are positioned against the strand and are moved a certain distance to transport them, while at the same time the bars of the other group are lifted and returned to their starting position. The crossbars can be driven individually and combined in such a way that each bar, with the exception of the end bars of one group, lies between two bars of the other group. However, it is also entirely possible to drive two, three or even several successive beams, preferably connected to a common frame, and to combine them into a sub-group.

The invention also allows a combination of these options. In the vicinity of the mold, the strand shell is thin and may therefore only be unsupported for relatively short distances, but at the end of the strand guide it is already thick enough to withstand the ferrostatic pressure even over longer distances. A number of individually drivable crossbeam pairs are therefore preferably arranged in the vicinity of the mold, whereas subgroups of e.g. B. connect two or more pairs of crossbars that can be driven together.

The design of the stamp as a toggle allows a lightweight construction, e.g. B. from plates stiffened with longitudinal ribs, the relatively small length of the toggle lever arms subjected to pressure largely precludes the risk of kinking and does not require any increase in weight. A toggle lever drive that can be used for the purposes of the invention is shown in FIG. 4 illustrates which shows the four phases a, b, c, d of the movement sequence. In the vicinity of the knee joint 77, a link guide 78 is attached to the toggle lever arm 72, and a link guide 79 is attached to the other toggle lever arm 71, in the vicinity of its articulation point on the crossbar 7. In the guideways of the two, for. B. disc-shaped link guides 78 and 79 protrude pins of stationary cranks 78 'and 79', which are driven in the same direction, counterclockwise in Fig. 4 and offset from each other by a predetermined phase angle of about 90 °. The positions which the cranks 78 ', 79' assume at the beginning of the movement phases a to d are entered in the four figures. At the beginning of phase a, the crossbar 7 is placed against the strand which is transported in the course of this phase by the distance indicated by the arrow s. At the beginning of phase b, the lifting of the crossbar begins, which ends at the end of the phase, whereupon the return movement of the lifted bar (arrow h) begins, which lasts until the end of phase c. In phase d the bar is switched on again. The vector diagrams illustrate the path covered within each phase and the previous four phases, and does so in a simplified manner, namely in the form of a square or its sides. In Figure 4, the guideways of the link guides are drawn as straight elongated holes. In practice, it may be advisable to use curved guideways to coordinate the lifting and transporting movements of the crossbeam more precisely. Side-by-side toggle levers can be connected by means of cranks 89 and coupling rods 88 provided in the vicinity of their ends adjacent to the crossbeams and can be driven together (FIG. 5). It is then sufficient to drive one of the coupled cranks on adjacent and jointly driven toggle levers.

The motor drive power required for each pair of bars can be comparatively small, because the toggle lever mechanism ensures sufficiently large contact forces between the bars and the strand. It is therefore advisable to drive the pairs of beams or the coupled pairs of beams individually, because the motors, gears and all other components involved in the power transmission are light enough to allow them to be attached to the sides of the guide frame or the longitudinal spars of the frame, which is why Set up support brackets but no changes to the frame design are required. As drive motors, because compressed air and hydraulic fluid are practically always available, pneumatic or hydraulic flow machines are definitely possible, but above all electric motors, the reliable synchronization of which does not pose any problems. It is advisable to drive the two cranks closer to the strand of pairs of two mutually opposite, driven beams from only one motor M ₁ via a reduction gear and two cardan shafts emanating therefrom (FIG. 3). The lying near the knee joint crank of a toggle drive can be with its own motor M ₂ (Fig. 3, above) or by means of z. B. a chain drive (Fig. 3, below) driven by the other crank.

The movement of the crossbeams can basically be broken down into a transport movement and a positioning movement in various ways. This is very easily done with stamps of the type shown in FIGS. 6 and 7. In this case, the stamp is designed as a simple lever 111, at one end of which the crossbar 7 is fastened, for. B. articulated and the other end is pivotally connected to the piston rod 113 of a pneumatic or hydraulic drive 112. The actuator is double-acting. Of the two compartments 114, 115, into which the cylinder space of the drive unit is divided by its piston, the one further away from the lever 111, 114, is permanently connected to a compressed air source, e.g. B. a container containing air under a predetermined pressure. The piston is therefore continuously loaded in the direction against the strand, which depends on the piston surface and the pressure of the compressed air and is therefore adjustable by changing this pressure. The other cylinder compartment, 115, can optionally be connected to or separated from a pressure source, such as a container, which contains gaseous or preferably liquid pressure medium under higher pressure. If the compartment 115 is depressurized, the crossbar is set against the strand with the force which corresponds to the load on the piston with the compressed air contained in the compartment 114. If pressure medium is let into the compartment 115, the piston is lifted against the contact force due to the higher pressure prevailing in this compartment. This adjustment stroke can be limited by means of stops. In this way, the shut-off movement is impressed on the crossbeam. The transport movement of the crossbar can be produced with a drive in the manner of an oscillating crank loop. The lever 111 then has a slot 116 which is parallel to the piston rod 113 and into which projects a pin which projects from a stationary crank 117. The crank is advantageously arranged in the vicinity of the beam 7. The transport movement according to stroke and frequency is determined by the crank or its speed. The times in which the compartment 115 is connected to the associated container, must be coordinated with the crank rotation, as hardly needs to be discussed in more detail. It goes without saying that instead of one cylinder, two can be provided, in each of which one of two pistons seated on a common piston rod is accommodated.

Incidentally, the adjusting movement does not necessarily have to be derived by means of a pneumatic or hydropneumatic device; for this purpose, a nut 118 which can be moved in a non-rotatable and non-rotatable manner can also be articulatedly connected to the outer end of the lever, into which a non-displaceably mounted spindle 119 is screwed. The spindle can be driven by a motor 121 via a gear 120.

The difficulties encountered in realizing such or similar drive devices are much smaller than the discussions above suggest. For example, the cylinders can be assembled and advantageously be adjustably attached to the frame of the strand guide or to the frame in the normal direction to the strand surfaces to be supported, so that an adaptation to different strand thicknesses is very easily possible.

As already mentioned, strand guides designed according to the invention which do not contain large contiguous masses allow the transport movement of the strand to be divided into many small and rapidly successive steps, e.g. B. in thirty steps / min or more. The times during which the solidified strand shell is unsupported in sections are then only a few seconds and during these short periods of time there is only a very limited bulging, which is known to be relatively slow. the flexing of the strand shell detrimental to the formation of the desired strand structure is therefore reduced to an insignificant degree.

The frame 6 of the strand guide can also be designed in a simple manner, especially if it is intended for mounting frame frames.

As from the fig. 1a, 1b can be seen, the guide frame can have a number of continuous, essentially arc-shaped side members, e.g. B. box girders, with top straps curved or curved according to the shape of the strand. These longitudinal beams are immovable approximately in the middle against a foundation, and movable with both ends, advantageously vertically movable in the vicinity of their mold-side end z. B. against a surface of a stand 3 and near its other end horizontally movable against the foundation or a support block. Frame frames can be placed on the upper sides of all the longitudinal beams in a cylindrically curved surface with the desired arc shape of the cross section to be guided, and frame frames can be attached and detachably fastened to the carrier sections, for example by means of screws. As mentioned at the beginning, the adaptation to the arch shapes need not be strict. The frame or units assembled with them can be installed from the side and therefore do not need to be raised significantly above their installation height. It should be mentioned that guide frames 6 and the crossbeams 7, 8 of this type can also be viewed from below due to the lateral arrangement of the drive devices. The firm support of the arch support from below approximately in the middle between the movable supports of the arch ends guarantees a kink-free load even during operation, because the effects of temperature-related changes in length come into play at largely uninfluenced points.

As already noted, a cold or start-up strand is an essential accessory of every continuous caster. The inventive design of the walking beam holding and transporting the walking beam as a successive crossbar in the longitudinal direction of the strand allows the strand to be supported at many and relatively close to one another, because the crossbars can be relatively narrow and closely adjacent. For example, the center planes of adjacent crossbeams can project from each other by 4 dm and the adjacent lower beam edges from each other by about 1 dm. It is therefore possible to construct the start-up line from links which are connected to one another in an articulated manner, in which the distance between adjacent joint axes corresponds to the pitch of the transverse beam row, that is to say the distance between the central planes of adjacent transverse beams, that is, for example, also 4 dm. Such a start-up line can therefore be relatively short and smooth and relatively light, so that it can be easily minipulated. First of all (Fig.la) the space requirement is small. A cold strand 131 consisting, for example, of eleven links 132 can be carried by a running frame 133, which is not necessarily but advantageously attached to the top of the horizontal beam 2 or between the longitudinal beams of this beam construction and can be moved along the same. The cold strand lies on an endless chain or the like, 134, which can be driven by the same motor 135 as the chassis or by its own motor. 10 shows, in a representation corresponding approximately to FIG. 2, two transverse bars 7, 8 which can be driven with toggle levers, between which there is a link 132 of a cold strand. The links are designed as cross bars with a middle section corresponding to the length of the cross beams 7, 8, the cross section of which practically corresponds to the cross section of the strand to be produced. At this middle, a side rod section 136 connects on both sides, which with a longitudinal profile, z. B. is provided with one or more longitudinal ribs. This longitudinal profile stanchions are complementary to the longitudinal profiles of two, each on one side of the crossbars 7, 8, arranged approaches 137, 138. The interlocking profiles of the rod sections or approaches, the z. B. can be arranged on the correspondingly wide toggle arms 71, 81, secures the cold strand against lateral sliding out of the space between the opposing rows of crossbars.

At the end of the arcuate strand guide there is a straightening device (FIG. 1b), the tools of which are also designed as crossbars and are therefore designated as 7, 8 as they are. These crossbeams face each other in pairs, can be set against the strand 5, can be moved back and forth in the longitudinal direction of the strand and are supported against a frame with stamps. It is advantageous to use these stamps as toggle levers 71, 72; 81, 82 form and arrange each pair of bars in a frame. The toggle lever drive allows the required straightening forces to be applied without difficulty, which can be greater than the supporting forces for the bent strand section, because the strand is in any case already largely solidified in the region of the straightening device. For these reasons, the tools of the straightening device and their drives, which do not need to differ from those already described, can, if necessary, be dimensioned or designed to be stronger. In many cases it is possible to equip the strand guide and the straightening device with units of the same design, which is of course advantageous.

Cooling the strand, which is a problem that cannot be solved satisfactorily in the case of roller guides provided with rollers, is a difficult task. In the case of strand guides with longitudinal walking beams, the heat is extracted extensively and therefore gently, but it is not possible to change the cooling in the longitudinal direction of the strand. It is different with strand guides according to the invention, which allows different cooling of successive crossbars or crossbar groups without particular difficulties. For this reason, the continuous casting process can also be used for steels in which, due to their composition-related sensitivity to inadequately adapted heat removal, it has not previously been considered. The strand can be cooled uniformly at any point in a previously manageable manner, at least by means of the z. B. cooled crossbeams, where appropriate, in particular in the entrance area of the continuous sheet, cooling with the aid of sprayed-on coolant can also occur.

Even if only one plunger, toggle lever or swivel lever of one of two mutually opposing crossbeams in the frame of the strand guide, in particular on a frame frame, is displaceably fastened against the action of an elastic or constant force, the supporting forces acting on the strand are limited upwards. If, however, both crossbeams of a pair of crossbeams are slidably held against such a force, the arch shape of the strand is not rigidly fixed; rather, the latter can maintain the shape within certain limits even when the contact forces occur, which it assumes only as a result of its support and gravity . This reduces the stress on the hardened strand shell, ensures that the strand is transported gently and makes it unnecessary to define an unchangeable arch shape from the outset. Incidentally, when using frame frames, any good approximation to a given arch shape is possible without extreme demands on the accuracy of the curved surfaces of the arch-shaped longitudinal members of the frame facing the strand, because each frame frame can be brought into the desired position easily and safely with the aid of support blocks will.

Claims (12)

1. A continuous casting plant, in particular for producing cast slabs, comprising a coolable open-ended mold (1), a straight or arcuate strand guiding means for transporting, cooling and optionally deflecting said strand, said guiding means comprising a guiding frame (6), two opposite banks of walking beams being mounted in said guiding frame, and drive means for moving each of said beams in successive cycles including moving said beam into engagement with said strand (5), moving it for a predetermined transportation step, moving said beam away from the strand and returning it into its initial position, the cycle of movement of the walking beams associated to one group being displaced by about one-half period form the cycle of movement of the walking beams associated to the other group, further comprising - if the strand guiding means is arcuate - a straightening means following said guiding means having drivable straightening tools mounted in the frame for straightening the strand, and all walking beams being transverse beams (7, 8, 100) extending transversely to the longitudinal center plance of the strand (5) and being arranged in pairs opposite to each other relative to the strand, characterized in that each transverse beam is connected to at least one prop (70, 80; 111) at one end of the latter and is supported by the prop or props against said guiding frame (6), that the props can be driven to move into engagement with and away from the transverse beam as well as for transporting and returning the transverse beam, and that preferably also the tools of the straightening means are traverse beams (7, 8) supported by props against the guiding frame or frame of the device and may be moved by means of the props into engagement with the strand and away from it.

2. The plant according to claim 1, characterized in that the two transverse beams (7, 8, 100) of a pair of transverse beams or of a plurality of successive pairs of transverse beams of the strand guiding means and/or of the straightening means together with the props (70, 80; 111) are mounted in a common frame (9) to form a unit which is detachably mounted on said guiding frame or frame of the device, respectively, and that preferably all units comprising the same number of pairs of transverse beams are identical (Fig. 2).

3. The plant according to claim 1 or 2, characterized in that the transverse beam (7 and 8, respectively) is supported by a single prop (70 and 80, respectively) extending substantially along the entire length of the beam (Fig. 2 and 3).

4. The plant according to one of the claims 1 to 3, characterized in that at least the transverse beam being nearest to the mold may be driven separately.

5. The plant according to one of the claims 1 to 4, characterized in that a plurality of successive transverse beams can be driven jointly, in particular two or three successive beams forming groups which are driven jointly, wherein a transverse beam is driven directly and the others are coupled with it for joint movement (Fig. 5).

6. The plant according to one of the claims 1 to 5, characterized in that all props (70, 80) supporting a transverse beam (7, 8) are levers mounted with one end on the transverse beam, preferably hinged to said beam, and the other ends thereof being pivotally connected to the guiding frame or the frame of the device, respectively (Fig. 3).

7. The plant according to claim 6, characterized in that the point of pivoting of the lever (70, 80; 111) or levers of at least one transverse beam of some, but preferably of all pairs of transverse beams is arranged on a pin loaded with a force and slidable in the opposite direction of said force, in particular on the piston rod (113) of a hydraulic cylinder (93; 112) or the like.

8. The plant according to claim 6 or 7, characterized in that the lever or fevers supporting a transverse beam (7, 8; 100) is a toggle lever (70, 80) and that both lever arms (71, 72 and 81, 82, respectively) of at least one toggle lever may be driven, that the toggle lever arm (71) on the side of the beam near the pivotal point on the transverse beams (7) and the other toggle lever arm (72) near the toggle joint (77) each comprise a coulisse guide (79 and 78, respectively) and that the pin of each crank (79', 78') rotatable on fixed axes engages in each slot of the coulisse.

9. The plant according to claim 6 or 7, characterized in that the lever or levers supporting a transverse beam (7) is a rocking lever (111) and that at least one rocking lever may be driven to move backwards and forwards, e. g. is provided with a coulisse guide (116) for a pin of a crank (117) which is rotatable on a fixed axis and that the end of the rocking lever distant from the strand (5) is movable towards the strand as well as away from it preferably by means of a hydraulic cylinder (112).

10. The plant according to one of the claims 6 to 9, characterized in that a ladle (73) is provided on the end of all levers supporting a transverse beam which faces the strand and that a cylinder in surface contact with said ladle, in particular a hollow cylinder (74) coolable on its interior surface, is provided on the transverse beam (7).

11. The plant according to one of the claims 1 to 10, characterized in that the transverse beam (100) comprises a plurality of cells (101) separated by webs (102), said cells being open on their front sides facing the strand and on their rear sides, or being covered on their rear sides with one rear wall (103) each provided with an opening (104) and that nozzles (105) for spraying the strand surface through the cells are provided on the beam rear side (Fig. 9, 10).

12. The plant according to one of the claims 1 to 11, comprising a cold strand having a plurality of members linked to each other, characterized in that the members are crossbars (132) _'of approximately the same width as the transverse beams (7, 8), that these crossbars comprise on one end or on both ends a section (136) with a longitudinal profile and that the strand guiding means comprises a profile along an extension (137) on one side or both sides, respectively, complementary to the profile of the bar sections.

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