Refrigeration – Liquid contacting discrete commodity – With article conveyer or transporter
Reexamination Certificate
1998-12-14
2001-01-30
Doerrler, William (Department: 3744)
Refrigeration
Liquid contacting discrete commodity
With article conveyer or transporter
C072S201000
Reexamination Certificate
active
06178768
ABSTRACT:
The invention relates to a cooling device for cooling a hot, moving metal strip by means of laminar coolant jets, consisting of at least one water box located across the direction of strip travel, into which at least one coolant supply line leads and from which a plurality of coolant discharge lines arranged at a distance from one another depart.
Cooling of a rolled hot strip in the area of the hot rolling mill, particularly on the runout roller table of a finishing line, is usually implemented in a laminar-flow strip cooling line, wherein the strip is cooled by laminar cooling water jets, the cooling effect being highly dependent on the formation of these cooling water jets. A laminar cooling water jet produces a considerably more intensive cooling action than a turbulent jet because a laminar cooling water jet is capable of breaking through the steam layer forming on the hot strip surface, whereby a higher cooling effect is achieved.
A laminar cooling water line basically consists of several series-connected water boxes extending across the direction of strip travel, each of which is provided with a plurality of cooling water discharge lines. A cooling device of this type is already known from DE-OS 21 07 664, where the cooling water discharge lines are comprised of siphon tubes arranged side by side across the direction of strip travel through which the cooling water is charged onto the strip surface.
When the cooling device is started, it is desirable that a laminar cooling water jet be directly obtained in order to immediately achieve a uniform cooling effect. A turbulent cooling water jet would lead to a reduced and nonreproducible cooling effect after starting. Analogously, a defined situation is required when the cooling device is stopped. Cooling devices of the above-quoted type have the disadvantage that after the cooling device has been stopped considerably large quantities of cooling water continue flowing in a partly entirely irregular manner so that nonreproducible conditions occur again and controllability is very limited.
Accordingly, the technical problem of the invention is to avoid these disadvantages and to propose a cooling device for cooling a hot, moving metal strip by means of laminar coolant jets where not only uniform flow conditions prevail in the coolant jets during operation as well as in the starting and stopping phases of the cooling device but also uncontrolled continued flowing of coolant after stopping the cooling device is reliably prevented.
This problem is solved by allocating a shut-off device to each coolant discharge line on the outlet side. The shut-off device is designed as slide gate or ball valve.
The cooling device is considerably simplified by mechanically coupling several or all shutoff devices allocated to the individual coolant discharge lines and by connecting them with a common adjusting drive.
According to an improvement, the mechanically coupled shut-off devices are comprised of an operating shaft which is provided with ports across the longitudinal axis of the operating shaft at the distance of the coolant discharge lines from one another and which is adjustable by means of an adjusting drive from a position in which the ports are in alignment with the coolant discharge lines into a position in which the operating shaft shuts off the coolant discharge lines and vice versa, wherein the operating shaft is supported in a multipart housing into which the coolant discharge lines lead and annular sealing shells inserted in the housing shells are arranged in the area of the operating shaft which is interspersed with ports, which sealing shells are provided with openings that are in alignment with the coolant discharge lines and with the ports which the operating shaft is interspersed with.
The flow conditions can be further stabilized by allocating a diffusor to each coolant discharge line that serves to focus the coolant jet, the shut-off device being connected downstream of the diffusor and the diameter of the port being larger than the diameter of the outlet in the diffusor.
According to another improvement, the coolant discharge lines are designed as downpipes projecting upwards essentially vertically in the water box, which offer advantages with regard to manufacturing engineering compared with the U-pipes known from DE-OS 21 07 664 and thus substantially reduce the costs of the cooling device.
Altogether, a considerably more compact assembly is obtained where the risk of damage resulting from ascending or sticking strip is considerably reduced.
Moreover, the flow conditions are improved by installing a flow stabilizer in each coolant discharge line. This flow stabilizer is comprised of at least one insert which preferably consists of two flow dividers, preferably plates, which are positioned at right angles to one another, which are inserted in the coolant discharge line and which divide the crosssectional area of the coolant discharge line into segments.
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Chen Jian
Djumlija Gerlinde
Oberhumer Johann
Schweighofer Andreas
Doerrler William
Ostrolenk Faber Gerb & Soffen, LLP
Voest-Alpine Indstrienlagenbau GmbH
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