Cooling device with breadth-dependent cooling action

A flat rolled article (2) passes through a cooling device (1) in a transportation direction (x) at the level of a passline (3). Spray bars (5, 6) extend transversely with respect to the transportation direction (x). The spray bars (5, 6) have, as viewed perpendicular to the transportation direction (x), in each case two outer regions (7, 8) and a central region (9) in between. A liquid cooling medium (13) can be fed into the regions (7, 8, 9) via respective dedicated, individually controllable valve devices (10, 11, 12). Flow rate profiles, pertaining to each region may be set, wherein each region (7, 8, 9) is triangular in shape. The central triangle and the two outer triangles combine to form a rectangle.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a 35 U.S.C. §§ 371 national phase conversion of PCT/EP2014/056771, filed Apr. 4, 2014, which claims priority of European Application No. 13163666.4, filed Apr. 15, 2013, the contents of which are incorporated by reference herein. The PCT International Application was published in the German language.

The present invention relates to a cooling device for a flat rolled product. The flat rolled product passes through the cooling device in a transportation direction at the level of a passline. The cooling device includes a cooling bed which has a plurality of spray bars. Each spray bar extends transversely with respect to the transportation direction, and the spray bars are arranged in succession in the transportation direction.

Viewed transversely to the transportation direction, each spray bar has two outer sections and a central section between the two outer sections. The flat rolled product passing through the cooling device is impinged upon with a central flow rate profile of a liquid cooling medium by outlet orifices arranged in the central section. When viewed transversely to the transportation direction, the central flow rate profile is at a maximum in the center and decreases toward both of its lateral edges.

The flat rolled product is impinged upon with a respective outer flow rate profile of the liquid cooling medium outlet orifices arranged in the laterally outer sections. When viewed transversely to the transportation direction, the respective outer flow rate profile is at a maximum at the respective outer edges of the outer sections and decreases toward the center. Thus, the outer flow rate profiles of the successive array of spray bars in each case define an outer triangle in which one side runs parallel to and one side runs transversely to the transportation direction.

The present invention further relates to a rolling train for rolling flat rolled product. The rolling train has at least one roughing stand and a number of finishing stands located downstream of the roughing stand. A cooling device of the type described is positioned immediately upstream of the roughing stand or downstream between the roughing stand and the finishing stand located immediately downstream of the roughing stand.

An example of a cooling device of the above type is known by the name Mulpic. A liquid cooling medium is injected into the central section on the one side and into the two outer sections on the other side via a respective dedicated, individually controllable valve device. The central flow rate profile defines a symmetric trapezoid. Its parallel sides run transversely to the transportation direction. The trapezoid and the two outer triangles laterally outside the trapezoid combine to form a rectangle. The valve devices are actuated such that the volume of cooling medium applied to the flat rolled product via the two outer sections and the volume of cooling medium applied to the flat rolled product via the central section are coordinated such that a temperature of edge sections of the flat rolled product is adjusted to match a temperature of a central section of the flat rolled product.

In some cases, the flat rolled product may have a temperature ridge, when viewed over the width of the flat rolled product, i.e. the flat rolled product is hotter on one side than on the other side. In such a case it would be of advantage to be able to cool the one side of the flat rolled product more intensively than the other side. The known device described above is unsuitable for this purpose.

SUMMARY OF THE INVENTION

The object of the present invention is to create possibilities to enable elimination of a thermal ridge of the above type.

According to the invention, a cooling device generally of the type described above is embodied such that a liquid cooling medium is injected into the sections via a respective dedicated, individually controllable valve device. The central flow rate profile defines a central triangle in which one side runs transversely to the transportation direction and the two other sides are of equal length. The central triangle and the two outer triangles combine to form a rectangle.

Within the scope of the maximum possible cooling medium volumes, this makes it possible to counteract a thermal ridge over the entire width of the flat rolled product. In contrast to the prior art, appropriate individual control of the two outer sections continues to remain possible, to cool the two edge regions of the flat rolled product to a lesser degree than to cool the central section of the flat rolled product. It is further possible, while cooling the two edges less intensively than the central section of the flat rolled product, to cool the two edges to different degrees of intensity.

In a simple embodiment of the cooling device, the valve devices are switched in a binary manner, i.e. they are either fully open or fully closed. In the simplest case there is no other possibility of influencing the volume of liquid discharged over the respective section. Preferably, however, the volume of liquid cooling medium injected into the sections can be set by adjustment of an operating pressure generated by a respective pump and/or by adjustment of a delivery volume effected by means of the respective pump. Furthermore, the valve devices may be embodied as servo valves or as proportional valves. In this case, the liquid cooling medium can be at a constant pressure upstream of the valve devices, for example due to pumps located upstream generating a constant pressure or because the liquid cooling medium is supplied from an overhead reservoir.

In a minimum configuration of the inventive cooling device, only a single spray bar is present. In this case, the spray bar is generally arranged above the passline. In individual cases, the spray bar can alternatively be arranged below the passline. Often, however, more than one spray bar is present. The number of spray bars consequently amounts to at least two. In this case at least one spray bar is preferably arranged above, and at least another below, the passline. This enables the flat rolled product to be cooled to an equal extent from both opposite sides.

Regardless of the number of spray bars, at least one of the spray bars may be arranged on a holding frame having a fixed position with respect to the passline. In this case, the spray bar may be assigned an adjusting device for setting a distance of the spray bar from the passline. This embodiment may be used in particular to maximize the distance of the spray bar from the passline during maintenance work on the spray bar and/or for example on a roller table defining the passline. An adjustment range for this distance can be varied as required.

Preferably, it amounts to at least 20 cm, for example at least 30 cm, in particular at least 50 cm. Greater values are also possible.

By means of the adjusting device, it is also possible to pivot a spray bar that is arranged on a holding frame fixed in position with respect to the passline through a pivoting angle about an axis of rotation.

The two measures of adjustment of the distance and the pivoting movement, can also be combined for the same spray bar. In this case, the corresponding spray bar is arranged on an intermediate frame which in turn is arranged on a holding frame which is fixed in position with respect to the passline. A respective adjusting device is assigned to the spray bar and to the intermediate frame. It is possible to set a distance of the spray bar from the intermediate frame by the adjusting device for the spray bar. In this case, the intermediate frame may be pivoted through the pivoting angle about its axis of rotation by the adjusting device for the intermediate frame.

Alternatively, the reverse approach can be adopted. In this case, the spray bar can be pivoted through the pivoting angle about the axis of rotation by the adjusting device for the spray bar. In this case the distance of the intermediate frame from the holding frame can be set by the adjusting device assigned to the intermediate frame.

If a pivoting movement is possible, the axis of rotation is typically arranged at the edge of said spray bar, when viewed transversely to the transportation direction, and runs parallel to the transportation direction. The pivoting angle can be set as required. Preferably, the angle is at least 20°. For example, the pivoting angle is at least 30°, at least 45° or at least 60°. Greater pivoting angles, up to 90° and beyond, are also possible.

The object is further achieved by a rolling train for rolling flat rolled product. According to the invention, a rolling train of the type cited in the introduction is embodied, and the cooling device is embodied according to the invention.

The above-described characteristics, features and advantages of this invention, as well as the manner in which these are realized, will become clearer and more readily understandable in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the accompanying schematic drawings

DESCRIPTION OF THE EMBODIMENT

According toFIG. 1, a cooling device1for a flat rolled product2, is passed through by the rolled product2at the level of a passline3in a transportation direction x. The passline3can be defined for example by the arrangement of a device located upstream and/or a device located downstream. The upstream device can be embodied for example as a caster, as a furnace or as a rolling stand. The downstream device can be embodied for example as a rolling stand, as a roller table or as a cooling bed. Other embodiments of that device are also possible.

The cooling device1has a number of spray bars5,6. It is also possible for only a single spray bar5,6to be present. Generally, however, a plurality of spray bars5,6are present, that is, at least two spray bars5,6. According toFIG. 1, preferably at least one of the spray bars5,6is arranged above and at least one other below the passline3. The spray bar5above the passline3is the upper spray bar5, and the spray bar6below the passline3is the lower spray bar6.

Possible embodiments of the upper spray bar5are explained below in conjunction withFIGS. 2 to 9. The same embodiments can be realized alternatively or in addition, for the lower spray bar6.

InFIG. 2, the upper spray bar5extends transversely to the transportation direction x. Viewed transversely to direction x, the spray bar5has two outer sections7,8and a central section9. Viewed transversely to direction x, the central section9is between the two outer sections7,8. A liquid cooling medium13can be injected into each of the two outer sections7,8and the central section9via a respective dedicated valve device10,11,12. The valve devices10,11,12may be actuated individually by a control device14. Each of the valve devices10,11,12is therefore controllable independently of the two other valve devices.

The flat rolled product2can be impinged upon with a flow rate profile V1of the liquid cooling medium13by outlet orifices15in the central section9. In an analogous manner, the flat rolled product2can be impinged upon with a respective flow rate profile V2, V3of the liquid cooling medium13by outlet orifices16,17in the two outer sections7,8. The flow rate profiles V1, V2, V3are referred to as central flow rate profile V1, left outer flow rate profile V2and right outer flow rate profile V3. The term “flow rate profile” herein, relates to a location-based profile, not a time-based profile. This will become more apparent with reference to the following explanations in relation toFIG. 3andFIGS. 4 to 7.

When the valve device10assigned to the central section9is fully opened, the central flow rate profile V1is applied to the flat rolled product2. According toFIG. 3, the central flow rate profile V1is at a maximum in the center, when viewed transversely to the transportation direction x. The central flow rate profile V1decreases linearly toward both lateral edges of the spray bar. The central flow rate profile V1accordingly defines a central triangle. One side of the central triangle runs transversely to the transportation direction x. The two other sides of the central triangle are of equal length. The central triangle is an isosceles triangle.

When the valve device11that is assigned to the left outer section7is fully opened, the left outer flow rate profile V2is applied to the flat rolled product2. According toFIG. 3, the left outer flow rate profile V2is at a maximum at the left-hand edge, when viewed transversely to the transportation direction x. The left outer flow rate profile V2decreases toward the center. The decrease proceeds linearly toward the center. The left outer flow rate profile V2accordingly defines a left outer triangle. One side of the left outer triangle runs parallel to the transportation direction x. Another side of the left outer triangle runs transversely to the transportation direction x. The left outer triangle is therefore a right-angled triangle.

When the valve device12assigned to the right outer section8is fully opened, the right outer flow rate profile V3is applied to the flat rolled product2. According toFIG. 3, the right outer flow rate profile V3is at a maximum at the right-hand edge, when viewed transversely to the transportation direction x. The right outer flow rate profile V3decreases toward the center. The decrease proceeds linearly toward the center. The right outer flow rate profile V3accordingly defines a right outer triangle. One side of the right outer triangle runs parallel to the transportation direction x. Another side of the right outer triangle runs transversely to the transportation direction x. The right outer triangle is therefore likewise a right-angled triangle.

It is apparent that the central triangle and the two outer triangles combine to form a rectangle. A resulting localized flow rate profile V, in other words the sum of the flow rate profiles V1, V2and V3, is indicated by a dashed line in the drawing inFIG. 5.

In order to realize the respective triangular flow rate profile V1, V2, V3, the outlet orifices15,16,17can be arranged for example according to the illustration inFIG. 2in a number of rows which succeed one another, when viewed in the transportation direction x. Alternatively or in addition, the outlet orifices15,16,17can be appropriately configured such that the volume of cooling medium13exiting the respective outlet orifices15,16,17varies.

The flow rate profiles V1, V2, V3shown inFIG. 3represent the maximum possible flow rate profiles. Said flow rate profiles V1, V2, V3are therefore applied to the flat rolled product2when the valve devices10,11,12assigned to the sections7,8,9are fully open and delivery volumes M1, M2, M3which are injected into the sections7,8,9are at a maximum. The delivery volumes M1, M2, M3can be constant. Preferably, however, they are individually continuously adjustable. As a result, depending on the settings of delivery volumes M1, M2,

M3a desired resulting localized flow rate profile V can be set within the adjustment limits. Several possible resulting localized flow rate profiles V are explained in more detail below in conjunction withFIGS. 4 to 7.

According toFIG. 4, the valve device11assigned to the left outer section7remains closed. The associated delivery volume M2is therefore0. The right outer section8is supplied with the maximum possible delivery volume M3(or a slightly smaller volume) via the assigned valve device12. A central delivery volume M1is supplied to the central section9via the assigned valve device10. The corresponding flow rate profiles V1, V3are indicated by dashed lines in the drawing inFIG. 4. The overall resulting flow rate profile V is indicated by a solid line. It is evident that a thermal ridge in the flat rolled product2can be corrected by means of the resulting flow rate profile V according toFIG. 4.

According toFIG. 5, the left outer section7is supplied with a central delivery volume M2via the assigned valve device11. A relatively high, though not the maximum delivery volume M3is supplied to the right outer section8via the assigned valve device12. The central section9is supplied with the maximum possible delivery volume M1(or a slightly smaller volume) via the assigned valve device10. The corresponding flow rate profiles V1, V2, V3are indicated by dashed lines in the drawing inFIG. 5. The overall resulting flow rate profile V is indicated by a solid line. It is evident that an enhanced cooling of the central section of the flat rolled product2can be effected with the resulting flow rate profile V according toFIG. 5, though the two edges are cooled to different degrees of intensity.

According toFIG. 6, a relatively high delivery volume M2is supplied to the left outer section7via the assigned valve device11. A slightly lower delivery volume M3is supplied to the right outer section8via the assigned valve device12. The valve device10assigned to the central section9is closed. The corresponding delivery volume M1is therefore0. The corresponding flow rate profiles V2, V3are indicated by solid lines in the drawing inFIG. 5. The overall resulting flow rate profile V corresponds in the left part to the flow rate profile V2, and in the right part to the flow rate profile V3. It is evident that the edges of the flat rolled product2can be cooled to different levels of intensity with the resulting flow rate profile V according toFIG. 6.

According toFIG. 7, the right outer section8and the central section9are supplied with delivery volumes M1, M3, which are combined in the right part of the flat rolled product2to form a constant flow rate profile V. The left outer section7is supplied with a delivery volume M2which is greater than the delivery volume M3supplied to the right outer section8. As a result, the left edge of the flat rolled product2is cooled more intensively starting from the center of the flat rolled product2. The resulting flow rate profile V therefore increases toward the left edge. Alternatively, the delivery volume M2supplied to the left outer section7could be less than the delivery volume M3supplied to the right outer section8. In this case the left edge of the flat rolled product2would be cooled less intensively starting from the center of the flat rolled product2, i.e. the resulting flow rate profile would decrease.

The delivery volumes M1, M2, M3explained hereinabove in conjunction withFIGS. 4 to 7serve as examples. Other combinations are also possible according to requirements.

In order to be able to adjust the delivery volumes M1, M2, M3, the valve devices10,11,12may be embodied as servo valves. Preferably, however, the valve devices10,11,12are switched in a binary manner. Depending on the actuation state, they are therefore either fully open or fully closed. No intermediate settings are assumed. In this case, insofar as the delivery volumes M1, M2, M3are adjustable, they are set by pumps18,19,20, each located upstream of the respective valve device10,11,12. The delivery volume M1, M2, M3effected by the respective pump18,19,20can be set directly. Alternatively or in addition, an operating pressure p1, p2, p3effected by the respective pump18,19,20in a respective feed line21,22,23can be adjusted.

In the embodiment according toFIG. 8, the upper spray bar5is arranged on a holding frame24. The position of the holding frame24is fixed with respect to the passline3. An adjusting device25is assigned to the upper spray bar5. The adjusting device25can, for example, be embodied as a number of hydraulic cylinder units. For example, two hydraulic cylinder units can be present which are mounted on the left and right on the holding frame24and on the upper spray bar5. A distance a of the upper spray bar5from the passline3can be set by means of the adjusting device25. An adjustment range δa, i.e. the difference between maximum possible distance a and minimum possible distance a, can be chosen as required. The adjustment range δa preferably amounts to at least 20 cm. It can also have greater values, for example 30 cm (or more) or 50 cm. Even greater values are also possible.

In the embodiment according toFIG. 9, the upper spray bar5is likewise arranged on the holding frame24, the position of which is fixed with respect to the passline3. An adjusting device25is also assigned to the upper spray bar5in the embodiment according toFIG. 9. In this case too, the adjusting device25can (for example) be embodied as a number of hydraulic cylinder units. The upper spray bar5can be pivoted about an axis of rotation26by means of the adjusting device25. According toFIG. 9, the axis of rotation26is arranged at the edge of said spray bar5, when viewed transversely to the transportation direction x. It preferably runs parallel to the transportation direction x.

A pivoting angle α, in other words the angle through which the upper spray bar5can be pivoted, can be chosen as required. Preferably, the pivoting angle α amounts to at least 20°. For example, the pivoting angle α can amount to at least 30°, at least 45° or at least 60°. Even greater pivoting angles a even up to 90° and beyond, are also possible.

The two adjustment options, that is, the setting of the distance a and the pivoting movement about the axis of rotation26, can also be combined.

According toFIG. 10, the inventive cooling device1is preferably employed in a rolling train in which the flat rolled product2is rolled. According toFIG. 10, the rolling train has at least one roughing stand27. In addition, the rolling train has a number of finishing stands28. The finishing stands28are located downstream of the roughing stand27, when viewed in the transportation direction x. The number of finishing stands28typically ranges between four and eight, and in most cases is five, six or seven. The cooling device1may be located immediately upstream of the roughing stand27, as indicated by the dashed outline inFIG. 10. Generally, however, the cooling device1is located downstream of the roughing stand27. It is therefore arranged between the roughing stand27and that finishing stand28which is located immediately downstream of the roughing stand27. In rare individual cases there can also be two cooling devices1present, in which event one of the two cooling devices1is positioned immediately upstream of the roughing stand27, and the other is positioned immediately downstream thereof.

The inventive cooling device1can be deployed as part of what is known as a laminar cooling system. Preferably, however, it is utilized within the context of a process known as intensive cooling. In an intensive cooling process, the operating pressures p1, p2, p3typically amount to at least 0.5 bar. In most cases they even lie above 1.0 bar. For example, they can range between 1.5 bar and 3.0 bar.

The inventive cooling device1has many advantages. In particular, flexible cooling of the flat rolled product2over its entire width can be realized in a simple manner.

Although the invention has been illustrated and described in greater detail on the basis of the preferred exemplary embodiment, the invention is not limited by the disclosed examples and other variations can be derived herefrom by the person skilled in the art without leaving the scope of protection of the invention.

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