EP0266302A1 - Cooling aggregate and method for cooling hotrolled rolling stock with/without direct patenting in presswater - Google Patents

Abstract

The cooling aggregate and method according to the invention are used for cooling shaped and hot-rolled rolling stock of steel or metal running through at rolling speed. According to the application, the heat extraction involving many known and still unknown imponderables is carried out, during the cooling of hot-rolled rolling stock, in a cooling aggregate with preferably three pressure spaces, as shown in Figures 1, 3 and 10, in order thereby effectively to avoid the danger of an unstable heat extraction, as shown in Figures 5 and 7. The particular actual cooling temperature is brought to the desired cooling temperature by varying the quantity of pressure water flowing into the convection pressure space (1), as a result of which the fraction of pressure water in relation to the vapour fraction in the pressure-water/vapour mixture in the evaporation pressure spaces is either reduced or increased, thereby reducing or increasing the heat extraction and consequently increasing or reducing the cooling temperature. By means of this cooling aggregate and method, it is possible to increase the heat extraction per dm<3> of pressure water considerably, with the result that the uniformity of cooling is improved and the quantity of pressure water to be used per ton of finished rolling stock can be lowered by 50 to 80%, as shown in Figure 11, and at the same time to carry out the cooling in such a way that no detectable undesirable structural constituents dependent on quality and caused by the cooling form in the finished rolling stock. <IMAGE>

Description

The invention relates to a cooling unit and a method for cooling hot rolled rolling stock, with / without direct patenting, in which pressurized water is pressed onto the hot rolled rolling stock surface.

When cooling hot rolled rolling stock with direct patenting, a cooling unit and process are useful that on the one hand enable the desired cooling temperature to be reached with little use of the agents and on the other hand prevent undesired overcooling of the edge zone of the rolling stock, which can lead to the formation of undesirable structural components in the finished rolling stock.

In the case of free cooling of hot rolled rolling stock, without direct patenting, a cooling unit and method are useful which, on the one hand, enable the desired cooling temperature to be achieved with little use of the agent and, on the other hand, enable the freely selected microstructure profile in the finished rolling stock to be achieved without undesirable structural components.

It is known that in the production of hot wide strip steel bars right down to the wire rod, the rolling stock, which is hot for rolling, is predominantly cooled with water in one or at intervals, partially with water and then with Blown air or air alone. In the cooling of hot wide strip 8000 m ³ / h and more cooling water are used in the spray nozzle and laminar water cooling, on the other hand wire rod with 5.5 mm diameter, from 1000 ° to 650 °, on which a wire rolling mill with 240 m ³ / h and the other cooled with 70 m ³ / h of cooling water. These widely differing amounts of cooling water show that in conventional cooling, a very different amount of heat is extracted from the hot rolled rolling stock per m ^{3 of} cooling water.

All cooling of hot rolled rolling stock with water, in particular with a small rolling stock thickness (rolling stock diameter), has in common that with the increasing rolling speeds and the increasing amounts of cooling water or the increasingly higher heat transfer values during cooling, the risk of undesired overcooling of the rolling edge zone increases. In order to avoid this danger, for example in the case of hot wide strip as well as wire rod, it is avoided to cool down in the spray nozzle and laminar water cooling, at which the rolling stock temperature is too close to that in the quality-related ZTU diagram during or after the cooling designated, hardness structure area approaches. In addition to the metallurgical consequences, an increasingly long cooling roller table is the result in the production of hot wide strip, the length limit is reached, a higher reel temperature. In the production of wire rod, which is predominantly today fanned primarily with water and secondarily with fan air and cooled in air, the result is that the wire rod must be placed on the air cooling belt at temperatures well above the conversion point. How great the cooling problem worldwide of fast-running wire rod, reports in Stahl und Eisen 102 (1982) _N r. 12, pp. 595/99. The problem was solved with the cooling of wire rod in pressurized water within pressure-cooled tubes with narrowed tube ends from the beginning of 1983 (documents DP 16 08 327 and DP 19 25 416, as well as mining and metallurgical monthly magazines, 131st year (1986), issue 11, P. 418). In 1986 it was reported from the cooling of hot-rolled wire rod, which is cooled with fan air on a conveyor belt, that the structure in each individual turn of the wire rod coil is four times uneven, since the two sections of each turn that lie in the area of the center of the conveyor belt are faster cool down than the sections lying on the two outer sides (Stahl and Eisen 106 (1986) No. 7, pp. 313/16). In order to avoid or to reduce the negative effect of this cooling of the fan-out windings in the fan air, the cooling in pressurized water should be able to be brought to a temperature below the conversion point without getting undesirable structural components in the wire rod, so that cooling with fan air can be completely or largely dispensed with .

No publication is known or accessible to the invention, which describes the phenomena when the heat is extracted from shaped, hot, continuous production goods made of steel or metal, in a pressure chamber by pressurized water, in detail; Using measuring records, he describes the different processes involved in extracting the heat from a hot rolled rolling stock in pressurized water within cooling units of different lengths with only one pressure space between the accumulation edges at the ends of the cooling unit and different amounts of pressurized water.

5 to 8 are shown for the measurement record at the cooling temperature, the measurement records of the pressure in the pressurized water line and that of the pressurized water quantities, and the symbol for the pressure chamber length. The numbers for the length of the pressure chamber and the amount of pressure water are ratio numbers.

The measuring records in Fig. 5 and Fig. 7 document that with a pressure chamber length 1 or 3 and a constant amount of pressurized water 3 or 10, the heat removal in itself became unstable, since the pressure chamber volume, based on the amount of pressurized water used , was too high and the cooling temperature dropped from 860 ° or 780 ° over the rolling stock run time in sowing steps to 720 ° or 660 °, whereas in the measuring records in Fig. 6 and Fig. 8 (in the area of constant water pressure ) as stable and constant. 5 and 7, the heat withdrawal increased in seconds to full evaporation, in which the steam pressure made the pressure chamber free of pressurized water for seconds until pressurized water flowed in again just as quickly and the process was repeated at an ever higher heat transfer value level, whereby the cooling temperature has dropped in a self-propelled manner so that the finished rolled product could not have a uniform structure over the length.

The invention is based on the object of being able to carry out the cooling of hot rolled rolling stock, from hot wide strip to wire rod, with / without direct patenting, in pressurized water in such a way that during and after the cooling thus carried out, no detectable undesirable, quality-dependent, cooling-related structural components form in the finished rolling stock can and the use of funds is comparatively low.

The object is achieved in that the cooling unit consists primarily of the pressure chamber of the convection cooling part, the convection pressure chamber, in the hot rolled rolling stock, primarily by convection, from the pressurized water heat pressed onto the warm rolling stock surface, preferably up to the boiling point of the pressurized water, is withdrawn and secondarily from the pressure chamber of the evaporative cooling part, the evaporative pressure chamber, in which further heat is removed from the rolling stock, primarily by the heat of evaporation, from the pressurized water-steam mixture pressed onto the rolling stock surface and generated in the convection pressure chamber, and that In terms of process, the cooling unit is preferably pressurized with the amount of pressurized water which, due to the cooling unit, is in equilibrium with the amount of heat to be extracted from the rolling stock and is necessary so that the heat is removed by heating the pressurized water in the convection pressure chamber and the heat is removed by the pressure water steam Mixture released Evaporation heat in the evaporation pressure chamber, the desired cooling temperature of the rolling stock is reached and the cooling in pressurized water and in the pressurized water / steam mixture is carried out in such a way that, during and after the cooling thus carried out, no undesirable, quality-dependent, cooling-related structural components detectable in the finished rolling stock can form.

• - daß die Stauränder zwischen dem Konvektions-Druckraum und dem Verdampfungs-Druck so bemessen sind, daß bei durchlaufendem Walzgut der verbleibende Durchströmquerschnitt ausreichend ist, daß die im Kenvektions-Druckraum entstandene Druckwasser-Dampf-Gemisch-Menge in den Verdampfungs-Druckraum einströmt und darin das Walzgut durch den Wärmeentzug, den das Druckwasser-Dampf-Gemisch als Verdampfungswärme dem Walzgut entzieht, abkühlt,
• - daß der Durchströmquerschnitt im Staurand am Walzguteintritt und -austritt, bezogen auf den verbleibenden Durchströmquerschnitt bei durchlaufendem Walzgut, in seinem Maß von der Walzgutoberfläche bis zum Staurand gleich oder 10 bis 30% größer oder geringer ist als dasselbe Maß bei den der verbleibenden Durchströmquerschnitte in den Staurändern innerhalb des Kühlaggregats, womit erreicht ist, da0 die Abkühlintensität des Kühlaggregats den Notwendigkeiten der unterschiedlichen Qualitätsgruppen und Abkühltemperaturen des abzukühlenden Walzguts angepaßt werden kann,
• - daß der Kühlaggregats-Körper in ein Unterteil und in ein Oberteil geteilt ist und beide Teile seitlich vorzugsweise eine Labyrinthdichtung angeordnet haben und das Oberteil abstandvariabel und kraftschlüssig geführt ist,
• - daß der Kühlaggregats-Körper ungeteilt ausgeführt ,
• - daß im Konvektions-Druckraum und/oder im Verdampfungs-Druckraum-Turbulenzerhöher und/oder Strömungsweise angeordnet sind, daß der Konvektions-Druckraum vorzugsweise zwischen zwei Verdampfungs-Druckräume angeordnet ist, die alle gleiche oder unterschiedliche Länge haben,
• - daß der Konvektions-Druckraum nach oder vor dem Verdampfungs-Druckraum angeordnet ist,
• - daß das Druckwasser-Ventil und das Druckwasser-Zuströmsteuerventil in eins zusammengefaßt sind,
• - daß die Regelung der Abkühlintensität während des Durchlaufs des Walzguts mit dem Druckwasser-Zuströmsteuerventil, durch Verändern der Druckwassermenge, erfolgt,
• - daß die Regelung der Abkühlintensität während des Durchlaufs des Walzgutes, bei geteilten Kühlaggregats-Körper, auch über abstandsvariable, kraftschlüssige Führung des Oberteils erfolgt,
• - daß bei Veränderung der Walzgutbreite, im Konvektions-Druckraum, ggf. auch im Verdampfungs-Druckrraum, seitlichvariabel fixierbare Stauränder an den Seiten angeordnet sind,
• - daß bei geteilten Kühlaggregats-Körper das Kühlaggregat von seinem geöffneten Zustand über den des Zusammenfahrens des Oberteils auf das Unterteil und dem dabei aufgeschalteten Druckwasser, stufenlos von der offenen Spritzwasser-Abkühlung zur geschlossenen Druckwasser-Abkühlung fürhbar ist,
• - daß dem Druckwasser feine Sand, z.B. schmiergelnde, beigegeben sind,
• - daß dem Druckwasser chemisch wirkende Zusätze, z.B. zur Unterstützung einer bestimmten Zunderbildung, zur Neutralisation, beigegeben sind,
• - daß dem Druckwasser chemisch wirkende Zusätze, z.B. zur Unterstützung einer bestimmten Zunderbildung, zur Neutralisation, beigegeben sind,
• - daß dem Druckwasser Luft zugegeben wird,
• - daß zum Vermeiden des Luftzutritts, während der Abkühlung in Druckwasser, zwei oder mehr Kühlaggregate mit je e--.₃m Verbindungsstück verbunden sind,
• - daß das Kühlaggregat an einen Wasser- und Kondensationskasten angeschlossen ist, selbst einen hat oder in einem liegt, der vorzugsweise mit Brausen ausgerüstet ist und ggf. an der Walzgut-Einlauf- und Auslaufseite je ein Druckwasser-Dampf-Gemisch-Rückhalteelement angeordnet trägt und Ablauföffnungen hat und
• - daß das Kühlaggregat.mit seinem festverbundenen Wasser-und Kondensationskasten vorzugsweise doppelt und parallel angeordnet ist, wobei wechselweise das eine oder andere Kühlaggregat, durch einfache Mechanik, in kürzester Zeit aus und in die Walzgutlinie gerückt wird.

Further training of the cooling unit and activities in the process are - that the volume of the convection pressure chamber is dimensioned so that the rolling volume of the remaining volume part is sufficient that the amount of pressurized water determined for cooling the intended amount of rolling stock from the pressurized water line over the pressurized water valve and the pressurized water inflow control valve, flows through the preferably centrally located inflow openings into the convection pressure chamber, extracting as much heat from the wire rod as is necessary to heat the pressurized water to a temperature determined by quality,

• - That the accumulation edges between the convection pressure chamber and the evaporation pressure are dimensioned such that the remaining flow cross-section is sufficient when the rolling stock passes through, that the pressure water-steam mixture quantity created in the convection pressure chamber flows into the evaporation pressure chamber and therein the rolling stock cools down through the removal of heat, which the pressurized water / steam mixture extracts from the rolling stock as heat of vaporization,
• - That the flow cross-section in the accumulation edge at the rolling stock entry and exit, based on the remaining flow cross-section when the rolling stock is passing through, is the same or 10 to 30% larger or smaller than the same dimension for the remaining flow cross-sections in the from the rolling stock surface to the accumulation edge Congestion inside the cooling unit, which means that the cooling intensity of the cooling unit can be adapted to the needs of the different quality groups and cooling temperatures of the rolling stock to be cooled,
• - That the cooling unit body is divided into a lower part and an upper part and both parts have preferably arranged laterally a labyrinth seal and the upper part is variable and non-positively guided,
• - that the cooling unit body is undivided,
• that in the convection pressure chamber and / or in the evaporation pressure chamber turbulence enhancer and / or flow are arranged, that the convection pressure space is preferably arranged between two evaporation pressure spaces, all of which have the same or different lengths,
• that the convection pressure chamber is arranged after or before the evaporation pressure chamber,
• - That the pressurized water valve and the pressurized water inflow control valve are combined in one,
• that the regulation of the cooling intensity during the passage of the rolling stock with the pressurized water inflow control valve takes place by changing the amount of pressurized water,
• - The regulation of the cooling intensity during the passage of the rolling stock, in the case of divided cooling unit bodies, also takes place via variable-distance, non-positive guidance of the upper part,
• - that when the width of the rolling stock changes, in the convection pressure space, possibly also in the evaporation pressure space, the sides of the variable-variable retention edges are arranged on the sides,
• - In the case of a divided cooling unit body, the cooling unit can be steplessly steered from the open spray water cooling to the closed pressure water cooling, from its open state to that of the moving together of the upper part onto the lower part and the pressurized water which is thereby activated.
• - that fine sand, eg greasy, is added to the pressurized water,
• that chemically active additives are added to the pressurized water, for example to support a certain scale formation, for neutralization,
• that chemically active additives are added to the pressurized water, for example to support a certain scale formation, for neutralization,
• - that air is added to the pressurized water,
• - That to avoid air access while cooling in pressurized water, two or more cooling units, each with e--. ₃ m connecting piece are connected,
• - That the cooling unit is connected to a water and condensation box, itself has or is located in one, which is preferably equipped with showers and, if necessary, carries a pressure water / steam mixture retaining element on the rolling stock inlet and outlet side and Has drainage openings and
• - That the Kühlaggregat.with its firmly connected water and condensation box is preferably arranged twice and in parallel, alternately one or the other cooling unit is moved out of and into the rolling stock line in a very short time by simple mechanics.

• - daß das walzwarme Walzgut geführt in Druckwasser abgekühlt wird, dadurch nur eine vergleichsweise geringe Druckwasser- menge benötigt wird,
• - daß sich während und nach der so durchgeführten Abkühlung, mit/ohne Direktpatentierung, im Gefüge des Fertigwalzgutes keine nachweisebaren, unerwünschten qualitätsabhängig-abkühlungsbedingte Gefügebestandteile bilden können,
• - daß diese physikalisch sicher führbare Abkühlung walzwarmen Walzguts im Produktionsfluß einerseits das Direktpatentieren in Druckwasser bei einem großen Teil der Walzgutqualitäten ermöglicht, andererseits das Direktpatentieren zu einem großen Teil schon vor dem anschließenden Direktpatentieren in Gebläseluft zuläßt und außerdem jede freie Abkühlung zum Erreichen der unterschiedlichen Oberflächengefügeausbildungen möglich macht,
• - daß mit der Zugabe von geeigneten Stoffen zum Druckwasser es möglich ist die Walzgutoberfläche bei der Abkühlung zusätzlich physikalisch und/oder chemisch zu behandeln,
• - daß das Kühlaggregat so einstellbar und das Verfahren so durchführbar ist, daß gegenüber der herkömmlich eingesetzten Kühleinrichtungen und Kühlverfahren mehr als 50%-80% Druckwasser eingespart wird.

The advantages achieved with the cooling unit and method according to the invention consist in particular in

• - that the hot rolled rolling stock is cooled in pressurized water, so that only a comparatively small amount of pressurized water is required,
• - that during and after the cooling thus carried out, with / without direct patenting, no detectable, undesirable, quality-dependent, cooling-related structural components can form in the structure of the finished rolling stock,
• - That this physically safe cooling of hot rolled rolling stock in the production flow on the one hand enables direct patenting in pressurized water for a large part of the rolling stock qualities, on the other hand allows direct patenting to a large extent even before the subsequent direct patenting in blown air and also allows any free cooling to achieve the different surface structure designs makes,
• that with the addition of suitable substances to the pressurized water it is possible to additionally treat the surface of the rolling stock physically and / or chemically during cooling,
• - That the cooling unit is adjustable and the method is so feasible that more than 50% -80% water pressure is saved compared to the conventionally used cooling devices and cooling methods.

If the pressure chamber according to FIG. 6 were a convection pressure chamber between two evaporation pressure chambers and the effective heat transfer value therein with an order of magnitude of 24,000 kcal / m ³ , h. ° C was equal to that in the convection pressure chamber, the cooled rolling stock would be of the order of magnitude Cooling temperature around 350 ° C, you would not reduce the amount of pressurized water.

9 shows the generally known diagram of the dependence of the heat flow density and heat transfer coefficient on the. Temperature difference between the heating surface and the water at the pressure of 1 bar, which is used as a representation aid, although the pressure of the pressurized water is higher in the cooling unit according to the invention, the GL values are likely to be on the line C-E.

Fig. 10 shows the process of heat removal with evaporation in a simplified schematic representation. The horizontally hatched area should schematically represent the proportion of pressurized water and the dotted area the proportion of steam. The left side should represent the pressurized water-steam mixture ratio when the pressurized water quantity is 1-, the right side with one of 1+.

The mathematical determination of the exact amount of pressurized water for cooling the different rolling stock qualities and dimensions to the different cooling temperatures is due to the large number of known and unknown imponderables effective (such as the scale thickness, adhesion and coverage% per cm ^{3 of} rolling stock surface) ) hardly possible, whereas it is easy to determine the amount of pressurized water at the individual cooling temperatures by measuring runs, which experience has shown that this can be done in production, since the main values can be measured in the simplest qualities. Of the comparatively small amount of pressurized water, about 80% should flow into the cooling unit as the base load amount via the pressurized water valve and the remaining amount of 20% via the controllable pressurized water inflow valve, which makes it possible for the amount of pressurized water currently required to flow in, to bring the actual cooling temperature currently present to the target cooling temperature is reached in a very short time, so that the target cooling temperature can be operated with a minimal bandwidth.

Two exemplary embodiments of the cooling unit and method according to the invention are shown schematically in the drawing and are described in more detail below.

1 and 2 show an embodiment of a cooling unit for cooling wide flat rolled stock, e.g. Hot wide strip.

The cooling unit consists primarily of the pressure chamber of the convection cooling section, the convection pressure chamber (1), with the accumulation edges (7) and (8) and secondarily from the pressure chamber of the evaporative cooling section, the evaporation pressure chamber (2), with the accumulation edges (9) and (10), plus the pressurized water line (3), the pressurized water valve (4), the pressurized water inflow control valve (5), the inflows (6), the lower part of the cooling unit (1), the upper part of the cooling unit (12), a seal (13) and the turbulence enhancer (15) Flow indicator (16), the laterally variable storage edges (17), the water and condensation box (19), plus the showers (20), the pressurized water / steam mixture retaining elements (21) and the water and condensate drains (22)

The pressurized water flows from the pressurized water line (3), via the pressurized water valve (4) with approx. 80% and via the pressurized water inflow control valve (5) with approx. 20%, through the inflows (6) into the convection pressure chamber (1), is heated to the boiling point by the continuous, low-rolling rolling stock, the pressurized water / steam mixture generated flows over the accumulation edges (7) and ( 8) into the evaporation pressure chamber (2), then cools _- then the hot rolled rolling stock by removing heat, which the pressurized water-steam mixture extracts from the rolling stock as evaporation heat, and leaves the cooling unit through the accumulation edges (9) and (10) .

The damming edges (7) and (8) are arranged to make it difficult for the pressurized water to leave the convection pressure chamber (1) and to separate the process of heat removal in the two pressure rooms (1) and (2) so that the physical possibility is created to keep the extraction of heat from the hot rolled material stable by convection and evaporation (bubble and film boiling) and to be able to use it as optimally as possible.

The steam portion of the pressurized water / steam mixture flowing out through the accumulation edges (9) and (10) is condensed on the underside between the roller table rollers with showers (20) for wide flat rolled stock and on the top by means of the pressurized water / steam mixture retaining elements (21 ), e.g. in the form of movable flaps, led into the water and condensation box (19) in the upper part (12) and condensed there with showers (20). Water and condensate drain through the opening (22).

3 and 4 show an embodiment of a cooling unit for cooling section steel, e.g. I-, L-profiles, reinforcement steel, wire rod.

The cooling unit for this consists in the main parts of the same parts as described for the cooling unit for wide flat rolled stock, with reference to FIGS. 1 and 2. The cooling unit body is, however, preferably in one piece (14), as a result of which the pressurized water / steam mixture emerging from the storage edges (9) and (10) flows directly into the water and condensation box (19).

In Fig. 4, a connecting piece (18) is shown, with which two or more cooling units can be connected, if no air should be able to reach the surface of the rolling stock during cooling in the pressurized water.

• - in einem Kühlaggregat, analog Fig. 5 mit nur einem Druckraum mit der Länge 1, bei der der Wärmeentzug pro dm³ Druckwasser 83 kcal beträgt und der Walzdraht dabei auf 795°C abkühlt und
• - in einem Kühlaggregat, analog Fig.10, mit einem Konvektions-Druckraum mit der Länge 1 und zwei anschließende Verdampfungs-Druckräume mit je der Länge 0,5, bei der der Wärmeentzug pro dm³ Druckwasser 198 kcal beträgt und der Walzdraht dabei auf 506°C abkühlt, eine Temperatur die schon unter der bei Betonbewehrungsstählen mit walzhitzevergüteter Oberfläche gefahrenen liegt. Das mit drei Druckräumen ausgestattete Kühlaggregat kühlt den Walzdraht mit rd. 7,5 m³/h auf 795°C - das sind rd. 60% Einsparung an Druckwasser, womit die Wirtschaftlichkeit des erfindungsgemäßen Kühlaggregats und Verfahrens besonders unter Beweis gestellt ist.

11 shows the cooling lines during the cooling of a wire rod with a diameter of 5.5 mm, at a final rolling speed of 80 m / s and an amount of pressurized water of 20 m ³ / h used.

• - In a cooling unit, analogous to FIG. 5 with only one pressure chamber with a length of 1, in which the heat removal per dm ^{3 of} pressurized water is 83 kcal and the wire rod cools down to 795 ° C. and
• - In a cooling unit, analogous to Fig. 10, with a convection pressure chamber with a length of 1 and two subsequent evaporation pressure chambers with a length of 0.5 each, in which the heat removal per dm ^{3 of} pressurized water is 198 kcal and the wire rod to 506 ° C cools down, a temperature that is already lower than that used for concrete reinforcement steels with a heat-treated surface. The cooling unit equipped with three pressure rooms cools the wire rod with approx. 7.5 m ³ / h at 795 ° C - that is approx. 60% savings in pressurized water, which particularly proves the economic viability of the cooling unit and method according to the invention.

Claims (20)

1. cooling unit and method for cooling hot rolled rolling stock, with / without direct patenting, in which pressurized water is pressed onto the hot rolled rolling stock surface,
characterized in that the cooling unit consists primarily of the pressure chamber of the convection cooling part, the convection pressure chamber (1), in which the hot rolled rolling stock, primarily by convection, from the pressurized water pressed onto the warm rolling stock surface, preferably up to the victory point of the pressurized water, is withdrawn and secondarily from the pressure chamber of the evaporative cooling part, the evaporative pressure chamber (2), in which further heat is removed from the rolling stock primarily by the heat of vaporization, from the pressurized water surface, which is generated in the convection pressure chamber, by the pressurized water-steam mixture In terms of process, the cooling unit is preferably pressurized with the amount of pressurized water which, due to the cooling unit, is in equilibrium with the amount of heat to be extracted from the rolling stock and is necessary so that the heat is removed by heating the pressurized water in the convection pressure chamber and the heat is removed by the pressure water steam Mixture evaporated heat me-in the evaporation pressure chamber, the desired cooling temperature of the rolling stock is reached and the cooling in pressurized water and in the pressurized water-steam mixture is carried out in such a way that during and after the cooling thus carried out, no undesirable, quality-dependent structural components detectable in the finished rolling stock can form . 2. Cooling unit and method according to claim 1, characterized in that the volume of the convection pressure chamber (1) is dimensioned such that the remaining volume part is sufficient when the rolling stock passes, that the determined for cooling the intended amount of rolling stock pressure water, the flows from the pressurized water line (3) via the pressurized water valve (4) and the pressurized water inflow control valve (5) through the preferably central inflow openings (6) into the convection pressure chamber (1), in which so much heat can be removed from the rolling stock which is necessary to heat the pressurized water to a temperature determined by quality. 3. Cooling unit and method according to claim 1 and 2, characterized in
that the accumulation edges (7) and (8) between the convection pressure chamber (1) and the evaporation pressure chamber (2) are dimensioned such that the remaining flow cross-section is sufficient when the rolling stock passes through that the pressurized water vapor generated in the convection pressure chamber -Mixed amount flows into the evaporation pressure chamber and cools the rolling stock through the heat removal which the pressurized water-steam mixture extracts from the rolling stock as evaporation heat. 4. Cooling unit and method according to claim 1 to 3, characterized in
that the flow cross-section in the accumulation edge at the rolling stock inlet (9) and outlet (10), in relation to the remaining flow cross-section when rolling rolling stock passes through, in its dimension from the rolling stock surface to the accumulation edge (9) and (10) equal or 10% to 30% is greater or less than the same dimension in the case of the remaining flow cross-sections in the accumulation edges (7) and (8) within the cooling unit, with the result that the cooling intensity of the cooling unit can be adapted to the needs of the different quality groups and cooling temperatures of the rolling stock to be cooled. 5. Cooling unit and method according to claim 1 to 4, characterized in that the cooling unit body is divided into a lower part (11) and an upper part (12) and both parts preferably have a labyrinth seal (13) arranged on the side and the upper part ( 12) is variable and non-positively guided. 6. Cooling unit and method according to claim 1 to 5, characterized. that the cooling unit body is undivided (14). 7. Cooling unit and method according to claim -1 to 6, characterized in that in the convection pressure chamber (1) and / or in the evaporation pressure chamber (2) turbulence booster (15) and / or flow indicator (16) are arranged. 8. Cooling unit and method according to claim 1 to 7, characterized in that the convection pressure space is preferably arranged between two evaporation pressure spaces (2), all of which have the same or different lengths. 9. Cooling unit and method according to claim 1 to 8, characterized in that the convection pressure chamber (1) is arranged after or before the evaporation pressure chamber (2). 10. Cooling unit and method according to claim 1 to 9, characterized in that the pressurized water valve (4) and the pressurized water inflow control valve (5) is combined in one (5). 11. Cooling unit and method according to claim 1 to 10, characterized in that the regulation of the cooling intensity during the passage of the rolling stock with the pressurized water inflow control valve (5) takes place by changing the amount of pressurized water. 12. Cooling unit and method according to claim 1 to 11, characterized in that the regulation of the cooling intensity during the passage of the rolling stock, with divided cooling unit body (11, 12), also via a variable-distance non-positive guidance of the upper part (12). 13. Cooling unit and method according to claim 1 to 12, characterized in that when changing the rolling stock width, in the convection pressure chamber (1), optionally also in the evaporation pressure chamber (2) laterally variable fixable storage edges (17) arranged on both sides are. 14. Cooling unit and method according to claim 1 to 13, characterized in that when the cooling unit body (11, 12) is divided, the cooling unit from its open state via the the moving together of the upper part (12) onto the lower part (11) and the pressurized water that is switched on, can be carried out continuously from the open spray water cooling to the closed pressurized water cooling. 15. Cooling unit and method according to claim 1 to 14, characterized in that the pressurized water fine sands, e.g. greasy, are added. 16. Cooling unit and method according to claim 1 to 15, characterized in that the pressurized water chemical additives, e.g. to support a certain scale formation, for neutralization. 17. Cooling unit and method according to claim 1 to 16, characterized in that air is added to the pressurized water. 18. Cooling unit and method according to claim 1 to 17, characterized. that to avoid air access during cooling in pressurized water, two or more cooling units are each connected to a connecting piece (18). 19. Cooling unit and method according to claim 1 to 18, characterized in that the cooling unit is connected to a water and condensation box (19), itself has or is in one, which is preferably equipped with showers (20) and possibly on the rolling stock inlet and outlet sides each have a pressurized water / steam retaining element arranged and have outlet openings (22) and 20. Cooling unit and method according to claim 1 to 19, characterized in that the cooling unit with its firmly connected water and condensation box is preferably arranged twice and in parallel, alternately one or the other cooling unit by simple mechanics, in the shortest possible time from and into the rolling line is moved.

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