EP0028686A1 - Cooling apparatus, especially for ingot and billet strands - Google Patents

Abstract

So-called spraying beams, being supports for spraying tubes or nozzles, are arranged in a continuous casting plant for cooling the strand along the surface thereof relative to the strand surface so that the width of the fan-shaped cooling water jets can be adapted to changing strand widths and thicknesses. The adjusting device for the spraying beams comprises two or more pivotable radius levers to which the spraying beams are connected, at least in zones, and which said levers can be locked in different pivoting positions so that the spraying beams or zones of spraying beams can be adjusted parallel with themselves and can be locked at different distances. The radius levers can also be pivotable along inclined planes so that the change of distance of the spraying beam is accompanied by a transverse displacement relative to the longitudinal axis of the strand.

Description

The invention relates to an adjusting device for so-called spray bars running along the surface of a strand of a continuous casting installation as a support for spray tubes or nozzles directed at the surfaces for applying a cooling medium to the surfaces, e.g. Water, to change the distance of the spray bars relative to the strand to adapt to changing strand widths and / or strand thickness.

In a continuous caster, it is known that the primary solidification of the strand takes place in the mold, which is followed by the secondary cooling and a residual cooling section. The first crystals solidify in the mold and form a thin strand shell or strand skin, which is further developed in the course of secondary cooling by applying a coolant (water, steam, water-air mixture, air) and the associated removal of heat until it completely solidifies . The most common coolant, namely water, is sprayed onto the free surfaces of the strand between the support elements of the strand guide by means of spray nozzles.

For cooling broad branches, it is known (DE-OS 1 936 306) to divide the strand guide following the mold into any number of cooling zones and to supply lines arranged centrally to the top and bottom of the strand Mistake. The supply lines have a large number of spray nozzles and can be raised and lowered to adapt to different line widths via a motor and a spindle with a spindle nut, so that the distance between the spray nozzles carried by a supply line and the line surface can be adjusted jointly.

However, the known adjusting device is not suitable for ensuring that it functions reliably. It must be borne in mind that continuous casting plants are provided with a closed cooling chamber encompassing the entire area of the spray cooling in the curved course of the strand guide. The conditions in the cooling chamber during the casting operation are characterized by the cooling water sprayed onto the hot strand. There is a wet steam mixture that has a temperature of approx. 80 to 100 ° Celsius in the area of the roller guide. The non-evaporated cooling water heated by the hot strand overflows all components and leaves deposits on the surfaces of the components due to the pouring powder and the washed-off scale. These conditions lead to considerable damage and impairment of the spindle adjustment device and cause the spindle adjustment to fail within a very short time.

The invention is therefore based on the object of improving the operational reliability of a continuous casting installation and of creating an adjustment device for the spray bars of a continuous casting installation which is free of faults and which is simple and quick to handle.

To achieve this object, it is proposed according to the invention that the spray bars can be adjusted at least in zones parallel to themselves via two or more steering levers and can be locked at different spacing positions from the surface of the strand. The steering lever guidance between the strand guiding frame and the spray bar is able due to its simplicity and robustness to withstand the adverse conditions described and to ensure the adjustment of the spray bars. The distance to the strand is adjusted by adjusting the levers on the line of the longitudinal axis of the strand. For this purpose, the spray bars, which are preferably formed on each cooling side of the strand provided not from a plurality of individual spray bars but from a single continuous spray bar extending over the entire area of the secondary cooling, are assigned pivotable adjusting levers. The pivotable adjusting levers, which otherwise act either on a steering lever or on the spray bar itself, can be fixed in their pivoting range in certain pivoting positions. The adjusting lever is pivoted by an operator or mechanically, in a very simple manner, until a hole in the adjusting lever, which is provided with several holes that define the spacing of the spray bar for each individual strand format in accordance with the formats to be cast, is opposite a corresponding hole in the strand guide frame . For example, by engaging a bolt in the bores, the pre-selected distance of the spray bars with the spray nozzles to the strand surface is reached in a very short time without any further adjustment activity.

Since in the continuous casting of billets and blocks with the same edge lengths during solidification there are approximately the same cross-sectional ratios everywhere, such formats are preferably cooled both on the top and bottom of the strand and on the other two sides, for which purpose supply lines provided with spray tubes or spray nozzles or Spray bars are arranged parallel to the strand from all four sides. Special considerations arise here when converting to different strand dimensions, because in addition to the lifting and lowering movement of the spray bars on the top and bottom of the strand and the positioning movement of the side spray bars relative to the side surfaces of the strand, each setting of the side spray bars to the center of the new one Format must be done.

This is mainly because during the continuous casting, the spray tubes should be perpendicular to the strand on the middle of the strand, so that the mostly very sensitive types of steel only come into contact with the spray cone in the middle of the strand due to the risk of cracks at the edges, without complex control measures to carry out the nozzle orifices themselves.

The spindle adjustment of the spray bars, which is known in the case of slab strands, is not suitable on the one hand because of the susceptibility to faults, which - as described - is additionally influenced by the difficult conditions in the cooling chamber of a continuous caster, and on the other hand, no adjustment can be carried out with the device, in addition to the movement to A further adjustment movement deviating therefrom or away from the strand - in this specific case to adapt to different strand centers - is permitted. Thus, in order to adjust the spray bars, it has hitherto required that the e.g. Spray bars attached to the scaffolding structure by means of bolts or screws had to be brought manually to the respective distance from the surface of the strand and to the new center of the strand using inserts and additional spacers on both sides. Even if several operators are used, the conversion can only be carried out with a considerable amount of time.

The invention is therefore also based on the object of avoiding the abovementioned disadvantages and, for spray bars which are assigned to a strand surface, the center of which shifts with changing strand width and / or strand thickness, in particular for block and billet continuous casting plants, a rapid and enable easy center-oriented adjustment of spray bars.

To achieve this object it is provided according to the invention that the steering levers can be pivoted in inclined planes, which form an acute angle with the respective spray plane running perpendicularly to the assigned strand surface through spray pipes or nozzles form such that with the change in distance of the spray bars a transverse displacement of the spray bars including spray pipes or nozzles takes place relative to the longitudinal axis of the strand. Due to the oblique arrangement of the steering levers at a certain angle to the strand, those spray bars that also have to be reset to the middle of the strand format when changing the format perform a movement transverse to the strand longitudinal axis with the movement in the strand longitudinal axis, so that the edge regions of the strand remain unaffected by the water as desired and stand the spray pipes in the middle of the strand.

According to the invention, it is further provided for a continuous caster with continuous spray bars extending over the entire secondary cooling section that the spray tubes or the spray nozzles are of different lengths and are increasingly brought closer to the surface of the strand in the lower areas, as seen from the mold. As is known, the secondary cooling section of a continuous caster can be divided into cooling zones, which can be switched independently of one another taking into account the steel quality to be cast, although it may well be the case that spray cooling is no longer necessary in the lowest cooling zone (s) and this zone is therefore switched off can be. It is certainly no longer necessary to apply cooling water to the strand in the lowest cooling zones, where it has become more and more solidified, and is sometimes harmful. The spray tubes of different lengths take this fact into account. Assuming that a uniformly continuous spray bar is adjusted once over the entire length of the strand guide and set to the desired distance from the strand, the shorter spray tubes at the beginning of the cooling section with a predominantly liquid strand core enable, for example, 80% exposure to the strand surface, while in the lower cooling area of the spray angle is substantially restricted by the longer spray tubes with a smaller distance from the surface of the strand, so that here, for example, there is only a 40% exposure to the strand surface.

• Fig. 1 eine schematische Darstellung einer Bogenstranggießanlage für quadratische Knüppel in der Seitenansicht und
• Fig. 2 einen Schnitt entlang der Linie I - I nach Fig. 1 .

The object of the invention is explained in more detail in the drawing with the aid of an exemplary embodiment. It shows

• Fig. 1 is a schematic representation of a continuous sheet caster for square billets in side view and
• FIG. 2 shows a section along the line I - I according to FIG. 1.

In the embodiment according to FIG. 1, steel flows from an intermediate container (not shown) into a continuous casting mold or chill mold 2. The chill mold 2 is followed by the strand guide frame 3, which comprises the strand 4 already solidified below the mold in the edge zones with the support rollers 3a arranged in the strand guide frame leads and transferred into the circular arc of the continuous caster.

With the exit from the mold 2, where the strand 4 is primarily cooled, the strand reaches the part of the continuous casting plant referred to as the secondary cooling section. During its passage through the support rollers 3a of the cooling section, heat is extracted from the strand 4 by water sprayed on by means of spray tubes or nozzles 6. For this purpose, spray bars 7, 8, 9, 10 extending over the entire length of the secondary cooling section are provided on the top and bottom of the strand as well as on the two other sides of the strand. The secondary cooling section can also be divided into cooling zones 5. The spray bars carry a large number of spray tubes 6, which must always be centered on the strand 4.

The spray bars 7, 8, 9, 10, which have a connection to a water supply via lines not shown, are connected to the strand guide or back-up roll stand 3 via a plurality of steering levers 12, 12 'pivotably mounted by means of bolts 11 in the manner of a parallelogram steering system . To adapt to different strand formats, each spray bar can be swiveled by means of a swivel The distance between the adjusting bracket 14 and the strand surface can be varied, as is shown in FIG. 1 for the spray bar 7 on the underside of the strand and for the spray bar 9 on the top side of the strand with the spray bar positions 7 ', 9' removed from the strand 4. With increasing solidification of the strand 4, the spray tubes 6 have a greater length, so that the distance A of the spray tubes to the strand surface in the lower region of the strand guide is less than the distance A 'in the upper part of the strand guide. With this measurement, it is possible to reduce the spray angle and thus the applied cooling surface S on the surface of the strand with increasing solidification of the strand.

As can be clearly seen from the simplified sectional view according to FIG. 2, special problems arise when different formats, for example 4 'and 4 "are to be produced on the continuous casting installation, since it must be guaranteed with regard to cooling that the spray tubes 6 are centered on the strand To ensure that these requirements are met, the spray bar 7 on the underside or fixed side of the strand must have a different setting than the spray bar 9 on the top side or the underside of the strand apply to the side spray bars 8 and 10. On the underside or fixed side of the strand, there is only a change in the strand width with changing strand cross-sections; the center of the spray tube 6 once set to the strand in the middle is - when the mold is changed - inevitably guaranteed when changing the distance . This also applies to the top or bottom of the strand, with a change in the height or thickness H of the strand being added, so that the adjustment stroke on the loose side must always be greater than on the fixed side. The adjustment itself is carried out by pivoting the actuating lever 14, which adjust the articulated steering lever 12 in the direction of the longitudinal axis of the strand, so that a spray bar 7, 9 approaches or removes the surface of the strand and one to the strand executes parallel displacement either in the direction of the mold or in the direction of the drive unit, which can be seen in FIG. 1, where the spray bar 9 is set further in the direction of the mold 2 than the reset spray bar 9 '. This offset V is, however, within the range of the distance between two adjacent support rollers 3a, which are in any case adjacent to one another with a large distance in billet and block systems.

In addition to the inclination towards the strand or away from it, the side spray bars 8, 10 also have to be adjusted to the middle of the strand so that this can be done without additional manipulations when adjusting, the side steering levers 12 'are in an inclined plane E is arranged pivotably, which extends at a certain angle α obliquely to the spray tube plane F running perpendicular to the assigned strand surface. When casting the smallest format, the side spray bars 8, 10, as shown in Fig. 2 in full lines, are set close and the spray tube 6 have only a small distance from the strand surface, which is designed so that the spray cone with the base area S does not cover the edge areas of the strand. With growing strand dimensions and as shown for the largest format 4 ', the dashed lines 8, 10 with the spray tubes 6 shown in broken lines are far from the surface of the strand, with the proviso that although the enlarged strand area is sufficient, the edge regions of the strand are again not water be charged. To do this, however, it is necessary that the spray bars 8, 10 in addition to the positioning movement inevitably involve an additional movement transverse to the longitudinal axis of the strand, i.e. in the direction of the change in thickness, in order to be newly aligned with the center of the other strand format, which is achieved by the inclined plane E, in which the steering levers 12 'pivot simultaneously with the change in distance.

As a result, with the device according to the invention, it is possible to set all the spray tubes alone in a time-saving manner by making sure that the setting lever 14 assigned to each spray bar and thus all steering levers 12 and 12 'are brought into a previously identified pivot position corresponding to the relevant strand format and are fixed there.

Claims (3)

1. Adjusting device for so-called spray bars running along the surface of a strand of a continuous caster as a support for spray tubes or nozzles directed at the surfaces for applying a cooling medium to the surfaces, e.g. Water, to change the distance between the spray bars relative to the strand in order to adapt to changing strand widths and / or strand thickness, characterized in that the spray bars (7, 8, 9, 10) parallel at least in zones via two or more steering levers (12, 12 ') are adjustable to themselves and can be locked in different distances. 2. Adjusting device according to claim 1 for spray bars which are assigned to a strand surface, the center of which shifts with changing strand width and / or strand thickness, in particular for block and billet continuous casting plants, characterized in that the steering levers (12 ') in inclined planes (E) are pivotable, which form an acute angle (α) with the respective perpendicular to the assigned strand surface through the spray tubes (6) or nozzles forming the spray plane (α) such that with the change in distance of the spray bars (8, 10) one Transverse displacement of the spray bars including spray pipes or nozzles takes place relative to the longitudinal axis of the strand. 3. Adjusting device according to claims 1 and 2 with continuous spray bars extending over the entire secondary cooling section of a continuous casting installation, characterized in that the spray pipes or nozzles (7, 8, 9, 10) baked are of different lengths are and in the areas removed from the mold (2) from schen are increasingly brought closer to the strand surface.

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