Patent Application
20060027163
The invention relates to an apparatus for cooling a strip of sheet metal with nozzles for a cooling liquid to be sprayed onto the bottom side of the strip, which nozzles are arranged beneath the strip in transversal rows relative to the feeding direction of the same.
For the purpose of rapidly cooling hot strips of sheet metal it is known (EP 0 695 590 A1) to spray a cooling liquid, especially water, against the bottom and upper side of the strip, which occurs with the help of jet nozzles which are arranged in longitudinal rows distributed over the width of the strip and extending in the feeding direction of the strip and, depending on each longitudinal row, are situated in a common median spraying surface. The fan jets of the nozzles aligned in the feeding direction of the strip are deflected in an alternating manner to both sides with the help of compressed air transversally to the feeding direction of the strip in order to achieve an even cooling of the strip of sheet metal. This is achieved only insufficiently. In order to prevent any dependence of the spraying surface on the pivoting angle of the fan jet nozzles and the uneven accumulation of cooling water on the upper side of the strip it has already been proposed to use full jet nozzles which are arranged in transversal rows beneath the strip relative to the feeding direction of the strip, so that the cooling liquid is only sprayed against the bottom side of the strip of sheet metal. Since in the case of full jet nozzles, which are pressurized with cooling liquid below a preferred, comparatively low pressure of up to 1 bar, the central spraying region shows a high cooling effect, one must expect a shrinkage of the strip of sheet metal starting from these central spray regions, leading to fluctuations in the thickness over the width of the strip, which cannot be prevented even when the full jet nozzles combined in nozzle beams are moved in an oscillating fashion to and fro transversally to the feeding direction of the strip. An additional factor is that in the longitudinal boundary region there is an inevitable different distribution of the sprayed cooling liquid as compared with the region situated in between, so that although it is possible to achieve a more even cooling with this known apparatus, the cooling is still insufficient to meet higher demands placed on a rapid and even cooling of the strip.
The invention is thus based on the object of providing an apparatus of the kind mentioned above for cooling a strip of sheet metal such that the strip of sheet metal can be cooled evenly over its width despite high cooling rates under avoidance of longitudinal strips caused by differences in thickness.
This object is achieved by the invention that the nozzles configured as fan jet nozzles form a common middle spraying surface for each transversal row and that covers are provided in the spraying region of the nozzles which are laterally adjacent to the strip of sheet metal.
The use of fan jet nozzles whose jets form a common middle spraying surface for each transversal row allows a substantially even distribution of the cooling liquid over the spraying surface, assuming a predetermined alignment of the jet which remains the same during the cooling relative to the bottom side of the strip, because the distribution of liquid which is uneven especially over the longitudinal extension of the spraying region of the individual fan jet nozzles can be offset sufficiently through a respective overlapping of the individual spraying regions. An additional factor is that as a result of the covers which are laterally adjacent to the strip and are in alignment with the bottom side of the strip it is possible to ensure a cooling meeting the conditions in the region between the longitudinal edges, because a wetting of the upper side of the strip in the region of the longitudinal boundary can be avoided which would occur otherwise due to unavoidable turbulent flows, so that the desired even cooling over the width of the strip can be ensured right up to the longitudinal boundary region.
Especially advantageous boundary conditions can be maintained when the covers are in alignment with the bottom side of the strip. The lateral covers in alignment with the bottom side of the strip form a spraying surface extending beyond the width of the strip which enables comparable reflection conditions for the sprayed cooling liquid beyond the edge of the strip.
In order to advantageously utilize the desired effect of lateral covers it is necessary to ensure a low distance between the longitudinal edges of the strip and the laterally adjacent covers. For this purpose, the covers can be displaced transversally to the feeding direction depending on the course of the longitudinal edge of the strip of sheet metal, which can be realized for example in a simple way from a constructional standpoint by scanning the longitudinal edges of the strip and a control device triggered by said scanning for the actuating drives of the covers.
The even sudden use of strip cooling must not be impaired by disturbing influences such as cooling liquid reflected from the housing walls. The same applies to the outlet region of the cooling section. In order to avoid such disturbing influences on the one hand and in order to secure a constructional limitation of the cooling section on the other hand, the spray region of the nozzles in the feeding direction of the strip can be limited by a deflection device for the cooling liquid which is provided beneath the strip of sheet metal. The portion of liquid sprayed by the closest transversal row of nozzles against the deflection device is diverted from the strip before it meets the lower side of the strip, which provides advantageous constructional conditions, especially when the nozzles of the transversal rows at the front and back in the feeding direction of the strip can be set in their inclination about an axis extending in the direction of the transversal row.
The subject matter of the invention is shown by way of example in the drawings, wherein:
The illustrated apparatus for cooling a strip 1 of sheet metal which is conveyed out of a continuous furnace 2 with the help of a supporting air cushion comprises several spray beams 4 and 5 which extend transversally to the feeding direction 3 of the strip 1 of sheet metal and are situated beneath the strip 1 of sheet metal, with the nozzles 6 of the spray beams 4 and 5 configured as fan jet nozzles being arranged in mutually offset transversal rows, as is shown in
As is shown especially in
In order to keep the distance between the longitudinal edges of the strip 1 and the lateral covers 2 sufficiently small, the covers 10 are held in a displaceable manner in guides 11 extending transversally to the feeding direction 3 and are connected with actuating drives 12, which are controlled according to
To ensure that cooling conditions can be observed which are substantially relieved from any disturbing influences in the front and rear end regions of the cooling section defined by the nozzle beams 4, 5, this cooling section is delimited by deflection devices 15 for the cooling liquid which are provided beneath the strip 1 of sheet metal. These deflection devices 15 each consist of a boundary wall 16 with a deflection profile 17 overlapping the same at a distance, as is shown especially in
It is understood that an additional influence can be taken on the cooling effect by a change of the distance of the nozzle beams 4 and 5 from the bottom side of the strip and by a change of the pressurization of the cooling liquid. An advantageous pressurization for the cooling liquid is a pressure of between 1 bar and 3.5 bar.
| Number | Date | Country | Kind |
|---|---|---|---|
| A 1336/2004 | Aug 2004 | AT | national |
