The present invention relates to a device for straightening a stream for cooling a roll or a metal strip or to a straightener. The present invention further relates to a device for cooling a roll or a metal strip.
State-of-the art discloses numerous cooling devices for cooling rolls, metal strips or metal sheets wherein, e.g., air, oil emulsion, or water is used.
In some cases, cooling medium is applied simply from cooling medium outlet to to-be-cooled rolls or to-be-cooled strips in large amounts. The drawback of this, among others, is the use of a large amount of cooling medium which either is lost for subsequent processes or is returned back and, possibly, must be treated at a great cost. A further drawback consists in a poor heat transmission rate per unit of volume to the applied cooling medium. Also, a controlled and varied degree of cooling in the width direction of the roll or strip is not possible with many known devices.
Other developed devices include spray bars which extend over the width of a strip or a roll. Such spray bars often include hollow bodies which are filled with cooling water and which include outlet openings along the width direction through which the cooling water can reach the strip.
Japanese Publication JP 11057837 A discloses an embodiment of a cooling device in which water from a vessel can be fed onto a metal strip through a slit extending in the width direction of the metal strip. The drawback of such constructions consists in that water is not applied to the metal trip in a controlled manner. The relative speed between the cooling water and the metal strip is low and the used water is not adequately used for cooling. In addition, the streams which exit such cooling devices, are very turbulent, not controlled, and/or have, when exiting, an increased thickness of the boundary layer. Turbulent cooling medium streams or cooling medium streams with a large thickness of the boundary layer result generally in a relatively poor heat transmission coefficient and, thus, decrease the cooling efficiency. A further drawback consists in that the produced streams cannot be adequately defined or calculated, whereby the control or regulation of the cooling becomes more difficult.
In summary, the object of the invention is to provide a device that would contribute to efficient cooling of a roll or a metal strip.
In particular, a device for straightening the stream should be provided that would insure that a less turbulent stream with a smaller boundary layer or a straightened stream can be produced.
A further object consists in providing an improved device for cooling a roll or metal strip.
Advantageously, at least one of the above-mentioned drawbacks should be eliminated.
The object of the invention is achieved by providing a device for straightening a cooling medium stream for cooling a roll or a metal strip according to claim 1. The device includes, advantageously, a hollow body extending at least over a portion of a width of the roll or the metal strip and a tube located in the hollow body and extending in a width direction (transverse to the cast or rolling direction) of the roll or the metal strip wherein the hollow body is divided in several chambers (segments) in the width direction of the roll or the metal strip, and the tube has openings for feeding the cooling medium from the tube in the chambers of the hollow body, and the chambers each has an opening for outflow of the cooling medium from the hollow body. According to the invention, the chambers each has a channel formed between an inner wall of the hollow body and the tube for conducting the cooling medium from the openings of the tube to the openings for outflow of the cooling medium from the hollow body, wherein a cross-section of the channel narrows at its downstream-located end or widens, looking in, at the downstream-located end.
With this arrangement and the provision of a narrowing shape of the channel, the fluid is accelerated and straightened. Thereby, the turbulence can be reduced and the boundary layer diminished. The term “boundary layer” is familiar to one of ordinary skill from the field of fluid dynamics. Mostly, the thickness of the boundary layer of a fluid stream is viewed as the thickness in which the streaming fluid has a velocity less than 99% of its free outer velocity. Further, by dividing the hollow body in several chambers (in the width direction), a straightening action is also achieved.
The openings of the tube are located preferably in all of the embodiments, at the side remote from the hollow body openings, so that the cooling medium leaves the tube in a flow direction opposite the outlet of the hollow body. After leaving the tube, the cooling medium is guided along the outer side of the tube in a reversed direction.
According to an advantageous embodiment, the tube is so arranged in an interior of the hollow body that the cooling medium flows around a greater part (more than half of its circumference) of the tube. Generally, the tube can be arranged substantially centrally relative to the hollow body or its inner wall.
According to another advantageous embodiment of the invention, the channel continuously narrows in a downstream direction form half of its length toward the opening for outflow from the hollow body. With continuous narrowing of the channel in the flow direction, a low-turbulence flow is produced by the device.
According to yet another advantageous embodiment of the invention, the chambers are separated one from another by a respective separation wall. The separation wall separates a hollow space of the hollow body in the width direction, whereby the flow of the cooling medium through the tube can be enhanced even more.
Advantageously, the separation wall extends in a direction substantially perpendicular to the width direction of the roll or the metal strip.
According to a still another embodiment of the invention, at least some of the chambers have a stream separation wall extending essentially opposite the opening for outflow of the cooling medium from the hollow body, and at least two openings located in the tube are arranged essentially opposite the opening for conducting cooling medium in the respective chambers.
The openings for conducting the cooling medium in the chambers each is provided on one of the sides of the stream separation wall for separating the cooling medium that exits the opening of the tube, so that when cooling medium exit the openings of the tube, both partial streams which are limited, respectively, by the tube and the inner wall of the hollow body, are separated from each other, and flow on opposite sides of the tube in direction of the opening for outflow of the cooling medium from the hollow body and are combined there in a common cooling medium stream.
In other words, advantageously, a partial stream in the chamber from one of the two openings of the tube is conducted in a narrowing channel between the inner wall of the hollow body and the outer wall of the tube to the outlet of the hollow body. Both partial streams are advantageously separated, in the region of the hollow body opposite the outlet of the hollow body, from each other by a stream separation wall.
According to a further embodiment, the hollow body and likewise the tube have transverse to the width direction of the roll or the metal strip, a triangular cross-section, and the outlets of the hollow body each is provided essentially at a tip of its triangular cross-section. Such shape of the hollow body or the tube can be easily produced and is extremely effective for obtaining a straightened and accelerating stream.
The distance between the inner wall of the hollow body extending in the direction of the outlet and the outer wall of the tube located opposite the inner wall advantageously diminishes in the flow direction of the cooling medium or downwardly. Further, such shape facilitates calculation or permits to predict the flow of the cooling medium through the device.
According to a yet further embodiment of the invention, of the hollow body and alternatively, the tube likewise have, transverse to the width direction of the roll or the metal strip, a drop-shaped cross-section. Here, likewise the hollow body has its outlets each is provided essentially at a tip of the drop-shaped cross-section. Such drop-shaped profile serves for producing even a smaller turbulence of the stream.
According to a still further embodiments of the invention, the inner wall of the hollow space is edge-free. Advantageously, the inner wall of the hollow space is free of projecting edges or free from projectings sharp kinks.
Further, the present invention includes a device for cooling a roll or a metal strip, including a cooling shell adjustable relative to the roll or the metal strip, at least one nozzle for feeding the cooling medium in a gap between the cooling shell and the roll or the metal strip, wherein the nozzle has an inlet region and an outlet region for the cooling medium stream. The device for cooling a roll or a metal strip also includes a device for straightening a cooling medium stream according to one of the above-described embodiments, wherein the openings for feeding the cooling medium out from the hollow body open into the nozzle inlet.
It is with such an arrangement that a straightened stream can be advantageously and efficiently used for cooling.
According to another embodiment of the device for cooling a roll or a metal strip, the outlet region of the nozzle opens into the gap between the cooling shell and the roll or the metal strip.
According to a further embodiment of the device for cooling a roll or a metal strip, the outlet region of the nozzle is connected with the cooling shell and at least partially is surrounded thereby so that the cooling medium can flow from the nozzle in the cooling shell.
Advantageously, the nozzle is arranged for directing a cooling medium stream in the gap substantially tangentially to the metal strip or roll surface.
According to a still further embodiments of the device for cooling a roll or a metal strip, the outlets of the hollow body open into the inlet region of the nozzle and, alternatively, are connected therewith.
According to a yet further embodiment of the device for cooling a roll or a metal strip, the cooling shell extends over at least a portion of a width and/or circumference of the roll. In case, a metal strip is cooled, the cooling shell extends over at least a portion of a width and/or length of the metal strip.
Generally, the outlet of the nozzle can be so arranged that the metal strip surface or the roll surface is subjected to the action of the nozzle stream in a direction opposite the movement direction.
The features of the described embodiments can be combined with each other or replaced one by the other.
Below, the figures of the embodiments will be shortly described. Further detail will follow from the detailed description of the embodiments. The drawings show:
In particular, it is desirable that the stream is as laminar as possible or not much turbulent. Reduction of the turbulence and/or reduction of the thickness of the boundary layer results in improvement of heat transfer between the roll and the cooling medium stream in the gap 43. It is further desirable to achieve as high as possible relative velocity between the stream and the to-be-cooled surface. The stream velocity noticeably influences the heat transfer coefficient and, thus, the cooling effect. To this end, the stream is preferably directed in the gap 43 in the direction opposite the rotational direction D of the roll 2.
As shown in
To prevent the cooling medium from reading the rolled metal strip 200, a stripper 400 that has essentially a plate-shaped form, can be arranged at the downstream end of the cooling shell 40. Such a stripper can be formed, e.g., of wood, hard tissue, or metal.
For directing the cooling medium in the gap 43, the nozzle inlet 45 should be supplied with cooling medium. This can be carried out, e.g., using an inventive variant of a feeding device or a stream straightener 1, as shown in
A device 1 for straightening a cooling medium stream, which is shown in
Advantageously, a channel which is formed between the inner wall of the hollow body and the tube 5, should narrow in the direction of the opening 9 of the hollow body 3. In other words, the hollow body 3 should include a channel that narrows, at least sectionwise, toward the downstream end or narrows at the downstream end. Advantageously, the inner wall of the hollow body 3 is free of edges or from projecting corners or edges. As it is particularly shown in
Different outflow openings 9 of the tube 5 can have advantageously different stream cross-sections in the width direction B. On the other hand, it is possible to vary the number of openings 9 in the width direction. With a greater number of the openings 9 in the width direction or a greater cross-section of the stream of the openings 9 in the middle of the device in comparison with the ends of the device 1 in the width direction or of the tube 5, e.g., the roll middle or the strip middle can be cooled to a greater extent than the edge regions.
Advantageously, the hollow body 3 has, in its half adjacent to its opening 8, inner walls extending toward each other in the direction of the opening 8.
The cooling medium that exits from the openings 9, is in this way, advantageously separated in two partial streams and is directed between the tube 5 and the inner wall of the hollow body 3 in the direction of the opening 8 of the hollow body.
The device 1 is divided in several chambers 7 or cooling medium conducting chambers 7 in the width direction B, with
The cross-sectional view in the width direction B, which is shown in
Advantageously, an opening 8 and two opening 9 for feeding the cooling medium in the chamber 7 are provided in at least one of the chambers 7. The openings 9 preferably are located on two sides of the stream separation wall 15. Additional openings or outlets 8, 9 are possible.
With a preferably fluid-tight segmentation or chamber-like division of the hollow body 3 in the width direction, among others, it is achieved that the stream produced by the device 1, is oriented transverse to the width direction B.
The chamber width can vary dependent on the used cooling medium. It can lie in a range, e.g., between 0.5 and 15 cm, preferably between 0.2 and 1.0 cm.
This segmentation can also serve to provide different quantities of the cooling medium or different streams in the width direction B.
In the embodiment shown in
By controlling the means 13 for variable closing the openings 9, the volume flow rate of the cooling medium can be varied over the width. Advantageously, the orifice plates are so adjusted that the strip or roll middle is cooled, by applying a greater amount of the cooling medium, to a greater extent than the edge regions. In principle, viewing in the width direction, an edge cooling is also possible or a constant application of the cooling medium over the strip or roll width.
The adjustment of the orifice plates or valves can be carried out, e.g., mechanically, hydraulically, electrically, pneumatically and, alternatively, wirelessly.
Generally, the channel can have two (separate) channels on opposite sides of the tube. The stream cross-section can, preferably, narrow or diminish in both channels downstream or in direction of the outlet from the hollow body.
Generally, the shape of the nozzle 41, 61 and/or of the device 10, 11, 111 can be optimized by numerical simulation. Further, a worker can regulate the pressure of the cooling medium or the flow rate dependent on the concrete use. The numerical simulation can take into account, e.g., pressure, flow rate, material constants of the cooling medium, or the temperature. Those can likewise depend on the shape and arrangement of the nozzle 41, 61.
The gap height between the cooling shell and the to-be-cooled roll or strip surface can be in a range between 0.1 cm and 2.5 cm and, preferably, between 0.2 cm and 1 cm.
The inlet region of the nozzle or the stream cross-section can have a clear dimension corresponding from 2 to 20 times of the gap height. The outlet region of the nozzle can have, preferably, a reduced dimension corresponding to from 1 to 3 times of the gap height.
Advantageously, the cooling medium can be fed to the device 1, 10, 11, 111 under pressure below 5 bar and, in particular, below 1 bar.
The above-described embodiments serve for better understanding of the invention and should not be understood as limiting the invention. The scope of the protection is defined by the application and the claims.
The features of the described embodiments can be combined with each other or be replaced one for another. This particular concerns the embodiments of
Further, the described features can be adapted to given conditions and requirements.
Number | Date | Country | Kind |
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10 2012 201 496.9 | Feb 2012 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2013/051833 | 1/31/2013 | WO | 00 |