Continuous-flow cooling apparatus and method of cooling strip therewith

Abstract

The invention relates to a continuous flow cooling device (3) for cooling a metal strip (1), in particular a metal strip made of aluminum or an aluminum alloy, having at least one strip flotation cooler (4), which has several upper nozzles (5) distributed along the strip travel direction (B), and several lower nozzles (6) distributed along the strip travel direction (B), wherein the metal strip (1) can be transported in a floating manner between the upper nozzles (5) and the lower nozzles (6), and the upper side of the strip as well as the underside of the strip can be supplied with cooling air in the process, and having several water cooling units (7), by means of which the metal strip (1) can be supplied with cooling water. This device is characterized in that the water cooling units (7) are integrated in the strip flotation cooler (4).

Claims

1. A continuous-flow cooling apparatus for cooling a metal strip, the apparatus comprising: at least one strip-flotation cooler through which the strip passes in a strip-travel direction; a plurality of upper air nozzles distributed in the strip-flotation cooler along the strip-travel direction above the strip; a plurality of lower air nozzles distributed in the strip-flotation cooler along the strip-travel direction below the strip; whereby the metal strip is transported in a floating and contact-free manner between the upper air nozzles and the lower air nozzles; a plurality of water nozzles in rows extending transversely to the strip-travel direction along the width of strip, between and separate from the air nozzles, and spaced apart in the strip-flotation cooler along the strip-travel direction below the strip; means for applying cool air through the upper and lower air nozzles both to an upper face of the strip and a lower face of the strip for floating the metal strip in the strip-flotation cooler; and a plurality of water coolers in the strip-flotation cooler for cooling and applying water through the water nozzles to the strip in the strip-flotation cooler.

2. The apparatus defined in claim 1, wherein at least one of the water coolers is provided in each of a plurality of intermediate spaces between two respective lower air nozzles or upper air nozzles that immediately succeed each other in the strip-travel direction.

3. The apparatus defined in claim 1, wherein the strip-flotation cooler further has one or more upper nozzle boxes each having a plurality of the upper air nozzles, one or more lower nozzle boxes each having a plurality of the lower air nozzles, and water coolers in the vicinity of the lower nozzle boxes or in the vicinity of the upper nozzle boxes and/or between the nozzles of two succeeding nozzle boxes.

4. The apparatus defined in claim 1, wherein the upper air nozzles are spaced along the strip-travel direction so as to be offset relative to the lower air nozzles and to float the metal strip in a sinusoidal or wavelike manner.

5. The apparatus defined in claim 1, wherein the upper air nozzles and the lower air nozzles are aligned in respective pairs one over the other when seen from the side.

6. The apparatus defined in claim 5, further comprising, in addition to the aligned upper nozzles: additional air nozzles between the upper air nozzles so as to be offset with respect to the lower air nozzles and thus aligned with the nozzles of the water coolers.

7. The apparatus defined in claim 1, further comprising: at least one additional water cooler upstream of the strip-flotation cooler.

8. The apparatus defined in claim 2, wherein the metal strip is cooled between two adjacent lower nozzles or upper nozzles by the water cooler provided in the respective intermediate space by a temperature difference of no more than 100° K.

9. The apparatus defined in claim 1, wherein only water is supplied to the water nozzles and only air is supplied to the air nozzles.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention is explained in further detail below with reference to a schematic drawing that illustrates only one embodiment.

(2) FIG. 1 shows a system according to the invention for heat treating an aluminum strip with a continuous-flow cooling apparatus according to the invention;

(3) FIG. 2 is a large-scale detail from FIG. 1 in the vicinity of the continuous-flow cooling apparatus;

(4) FIG. 3 shows a modified embodiment of the continuous-flow cooling apparatus according to the invention; and

(5) FIG. 4 shows a modification of the embodiment of FIG. 3.

SPECIFIC DESCRIPTION OF THE INVENTION

(6) The drawing shows a system for heat treating a metal strip 1 that is preferably an aluminum strip. The system has a treatment furnace 2 that is a strip-flotation furnace and in which the metal strip is heat treated. This can involve solution annealing or the like.

(7) Furthermore, the system has a continuous-flow cooling apparatus 3 that is downstream of the strip-flotation furnace 2 in a strip-travel direction B. The continuous-flow cooling apparatus 3 according to the invention has a strip-flotation cooler 4 having a plurality of upper air nozzles 5 distributed along the strip-travel direction and a plurality of lower air nozzles 6 also distributed along the strip-travel direction, with the metal strip 1 being transported in a floating and hence contact-free manner between the upper nozzles 5 and the lower nozzles 6. Cooling air is applied both to the upper face of the strip and to the lower face of the strip through the air nozzles 5 and 6. Moreover, the continuous-flow cooling apparatus 3 has a plurality of water coolers 7 with which water is applied to the metal strip 1.

(8) According to the invention, these water coolers 7 are integrated into the strip-flotation cooler 4. Upper intermediate spaces 5a and lower intermediate spaces 6a are formed within the strip-flotation cooler 4 between the individual upper air nozzles 5 and the individual lower air nozzles 6, and these intermediate spaces 5a and 6a are each provided between two upper nozzles 5 or two lower nozzles 6 arrayed in immediate succession in the strip-travel direction B and thus adjacent one another. In the illustrated embodiment, a water cooler 7 is provided in a plurality of lower intermediate spaces 6a and preferably in all intermediate spaces 6a that are formed within the strip-flotation cooler 4. Each of these water coolers 7 has one or more water nozzles and/or rows of water nozzles 8 that are arranged successively in the strip-travel direction B and extend transverse to the strip-travel direction B across the entire width of the strip.

(9) In this embodiment, the strip-flotation cooler has a plurality of upper nozzle boxes 9 each having a plurality of integrated upper nozzles 5, and a plurality of lower nozzle boxes 10 each having a plurality of integrated lower nozzles 6. The water coolers provided according to the invention are thus in the vicinity of the lower nozzle boxes 10, particularly between the individual lower nozzles of each nozzle box and also between two succeeding lower nozzle boxes 10.

(10) The possibility exists for the upper nozzle boxes 9 and/or the lower nozzle boxes 10 to be hung so that their vertical position can be adjusted such that, by adjusting the vertical position of one or both nozzle boxes, the spacing between upper nozzles 5 and lower nozzles 6 and thus the vertical spacing can be adjusted. Actuators or the like (not shown in greater detail) can be provided for this purpose.

(11) FIGS. 1 and 2 show the continuous-flow cooling apparatus 3 according to the invention in a first embodiment in which the upper nozzles 5 are spaced along the strip-travel direction B so as to be offset relative to the lower nozzles 6 and the metal strip 1 is caused to float in a sinusoidal or wavelike manner. In this embodiment, the water coolers 7 are thus aligned under the opposing upper nozzles 5 when viewed from the side.

(12) In contrast, FIG. 3 shows a modified embodiment of a continuous-flow cooling apparatus according to the invention in which the upper nozzles 5 on the one hand and the lower nozzles 6 on the other hand are arranged in pairs over one another, so that the strip is not caused to float in a sinusoidal or wavelike manner. In this embodiment as well, however, the water coolers 7 essential to the invention are provided in the intermediate spaces and therefore also integrated into the strip-flotation cooler 4.

(13) FIG. 4 shows an alternative embodiment of the continuous-flow cooling apparatus according to the invention. Starting from the embodiment according to FIG. 3 with staggered upper nozzles 5′ and lower nozzles 6, additional upper nozzles 5′ are provided between the upper nozzles 5. These additional air nozzles 5′ are thus aligned above the water coolers 7. The embodiment according to FIG. 4 thus represents a combination of the embodiments according to FIGS. 2 and 3, as it were. The air nozzles 5′ aligned above the water coolers 7 prevent any water that is applied to the lower face of the strip from traveling over the edges of the strip and onto the upper face thereof.

(14) The additional (upper) nozzles 5′ can also be connected to the corresponding (upper) nozzle boxes 9 and/or integrated into them. Alternatively, however, separately embodied additional nozzles 5′ can also be provided.

(15) The strip-flotation cooler 4 according to the invention makes it possible for the metal strip 1 that was previously heat treated in the strip-flotation furnace 2 to be cooled in an optimal manner. The cooling rates can be adjusted by the combined air and water cooling with sufficient speed as to freeze in the metallurgic characteristics achieved during the heat treatment. However, excessively rapid cooling rates can be avoided, so that flaws created during cooling of the strip are kept within acceptable limits. It is especially advantageous in this regard that optimal variable adjustment options exist, so that the cooling process can be adapted optimally to the desired situation.

(16) Very simple construction is used here overall, the air nozzles are conventional air nozzles, and the water coolers have conventional water jet nozzles so that “combined” water/air and misting nozzles as used in the prior art are dispensed with.

(17) It can also be seen in FIG. 1 that the system for heat treating the aluminum strip also has an additional strip-flotation cooler 11 that operates in a conventional manner without water cooling and that is downstream of the strip-flotation cooler 3 in the strip-travel direction B. Therefore, according to the combined water and air cooling according to the invention, additional cooling occurs with the aid of a conventional strip-flotation cooler 11.

(18) Moreover, it can be seen in FIG. 2 that the continuous-flow cooling apparatus downstream of the furnace 2 can also have an additional water cooler 12 upstream of the strip-flotation cooler 2 on the intake side. A so-called “hard quenching” mechanism is thus made available at the intake, and conventional, very rapid water cooling can also be optionally used as needed. The illustrated system is thus characterized by a high level of flexibility and variability.

(19) Even though the figures show embodiments in which the continuous-flow cooling apparatus 3 according to the invention is downstream of a strip-flotation furnace 2 and thus from a temperature control unit, the invention also includes embodiments in which the continuous-flow cooling apparatus 3 is downstream of another type of processing device through which the strip travels in a heated stated or in which the strip is heated. In any case, the strip emerges from the strip treatment device in a heated state and enters the continuous-flow cooling apparatus 3.