EP2104745B1 - Device for the suspended guidance of strip-shaped material - Google Patents

Abstract

A device for the levitated guidance of web-shaped material, particularly metal strips, with at least one first radial fan and with at least one flow channel system that is assigned to the at least one first radial fan provides that the at least one first radial fan generates a fluid flow that is transported through the at least one flow channel system to the surface of the web-shaped material for the levitated guidance thereof. The device is characterized in that at least one additional radial fan for increasing the pressure in the fluid flow is arranged in the at least one flow channel system downstream of the at least one first radial fan referred to the fluid flow direction.

Description

The invention relates to a device for the floating guidance of sheet material, in particular metal bands, with at least a first centrifugal fan and at least one of the at least one first radial fan associated flow channel system, wherein the at least one first centrifugal fan generates a fluid flow, which through the at least one flow channel system for Surface of the sheet material is transported to the floating guide thereof. Furthermore, the invention relates to a ribbon float furnace.

Devices of this type have long been known from the prior art (eg DE-OS 29 08 348 . DE 40 10 280 A1 . EP 08 64 519 B1 ). In these devices, a fluid flow is generated by one or more centrifugal fans, which is passed through a flow channel system and provided at its end nozzle system on the web material to be treated.

In a ribbon float furnace, a gas stream is generated in a furnace housing by means of one or more centrifugal fans, which is usually passed through a flow channel system on both sides of the belt running through the furnace housing and this leads floating and possibly heated or keeps at a certain temperature. For this purpose, heating elements are arranged in the flow channel system or in the space surrounding the flow channel system, which by Convection to heat the gas stream to the desired process temperature. At very high temperature (eg 870 ° C), the heat transfer to the gas stream takes place primarily by radiation.

In a number of applications, it is necessary to apply a metal strip at very high temperatures (e.g., 870 ° C) while floating. Here, there is the problem that the treatment gas has only a very low density and correspondingly low load capacity at said temperatures, which is particularly true for heavy metal bands, e.g. For copper strips with a material thickness> 2 mm, proves to be extremely problematic. In order to compensate for the loss of capacity associated with an increase in gas temperature, it is necessary to increase the peripheral speed of the centrifugal fans used so far that the stresses occurring at the individual fan blades, the permissible at the given high temperatures limit stresses even with high temperature resistant materials, such as Iconel® clearly exceed, which leads to a deformation of the fan blades. The maximum peripheral speed of the centrifugal fans resulting from these limiting stresses is therefore generally insufficient to cause heavy metal bands to float at high temperatures, even with optimized nozzle systems.

Especially in the EP 0864 519 A1 is a generic device for the floating guidance of web-like material, preferably metal bands, described in which the material web to be treated is guided horizontally through the device and on both sides, ie from above and from below, is blown. For this purpose, a radial fan is provided on each side of the web in each case, which generates a fluid flow, which is transported via an associated flow channel system to the surface of the material web.

In the US 5,118,366 Another device for the floating guidance of metal strips is described. In this case, the metal strip is blown only on one side, ie from below. For this purpose, a number of floating nozzle boxes are arranged below the metal strip. Furthermore, a fan is provided in a general gas supply line, which ensures the continuous circulation of the treatment gas. Departing from the central supply line, a separate supply line is provided for each nozzle box, in which a further fan stage is arranged to increase the pressure of the circulated treatment gas to the desired value.

The invention is therefore an object of the invention to provide a device for the floating guidance of web-like material, in particular of metal bands, of the type mentioned, which is also suitable for the treatment of heavy metal bands at very high temperatures.

1. a) die Vorrichtung bei im wesentlichen horizontaler Führung des bahnförmigen Materials den ersten Radialventilator und ein Strömungskanalsystem mit dem weiteren Radialventilator zur Beaufschlagung der Unterseite des bahnförmigen Materials mit der Fluidströmung umfasst, wobei ein weiteres Strömungskanalsystem zur Beaufschlagung der Oberseite des bahnförmigen Materials vorgesehen ist, welches von dem ersten Strömungskanalsystem in Strömungsrichtung vor dem weiteren Radialventilator abzweigt
   oder wobei
2. b) der erste Radialventilator als erste Druckstufe vorgesehen ist, wobei die durch den ersten Radialventilator erzeugte Fluidströmung in zwei das bahnförmige Material jeweils einseitig mit der Fluidströmung beaufschlagende Strömungskanalsysteme einströmt, wobei in jedem der zwei Strömungskanalsysteme der weitere Radialventilator als zweite Druckstufe vorgesehen ist

und wobei der erste Radialventilator mittig in der Vorrichtung neben dem durch die Vorrichtung transportierten bahnförmigen Material angeordnet ist und die zwei Strömungskanalsysteme punktsymmetrisch zueinander angeordnet sind.The object is achieved with a device for the floating guidance of sheet material, in particular of metal bands, according to the preamble of claim 1, characterized in that in the at least one flow channel system in the fluid flow direction behind the at least one first centrifugal fan at least one further centrifugal fan to increase the pressure in the fluid flow is arranged, wherein

1. a) the device comprises at substantially horizontal guidance of the sheet material, the first centrifugal fan and a flow channel system with the further centrifugal fan for acting on the underside of the sheet material with the fluid flow, wherein a further flow channel system is provided for acting on the upper side of the sheet material, which of the first flow channel system branches in the flow direction in front of the further centrifugal fan
   or where
2. b) the first centrifugal fan is provided as a first pressure stage, wherein the fluid flow generated by the first radial fan flows into two the web-like material in each case acting on one side with the fluid flow flow channel systems, wherein in each of the two flow channel systems, the further centrifugal fan is provided as the second pressure stage

and wherein the first centrifugal fan is arranged centrally in the device adjacent to the web-shaped material transported by the device, and the two flow channel systems are arranged point-symmetrically with respect to each other.

With the solution according to the invention, which is already known in principle from the centrifugal pump technology, but in the field of industrial furnaces is a novelty, it is now possible to produce a multi-stage pressure-enhanced fluid flow, the final pressure is high enough to heavy material web-like material at high and to safely float in the highest temperatures. Thus, a first partial pressure is generated in the first centrifugal fan, which in itself is not yet for the floating guidance of a heavy sheet-like material is sufficient, in which the stresses occurring on the blades of the centrifugal fan but these structurally not excessively burden. This first partial pressure serves as inlet pressure for the inventively provided further centrifugal fan. In this a further increase in pressure in the fluid flow is generated. In the flow channel system in the flow direction behind it, if necessary, further existing centrifugal fans, the pressure of the fluid flow can be further increased. The goal is always to achieve a pressure which is sufficient for the safe floating guidance of the web-like material. In this case, it is always ensured that the fan speeds required in the individual radial fans for the respective pressure increase are permanently below the above-specified material-dependent limit speed at which the limiting stresses acting on the fan blades would be exceeded.

In the device according to the invention, it is thus possible to produce pressures with a total of limited technical complexity, even at the highest treatment temperatures, which are sufficient to safely guide even heavy web-like material.

The web-like material to be suspended can be guided in different orientations by the device according to the invention. Preferably, the web-like material is guided substantially horizontally through the device and acted upon from below or from below and above with the fluid flow. It is also possible to guide the web-shaped material inclined through the device. In the case of a substantially horizontal guide of the sheet material is provided that the device comprises a first centrifugal fan and a flow channel system with a further centrifugal fan for acting on the underside of the sheet material with the fluid flow, wherein a further flow channel system for loading the top of the sheet material provided is, which branches off from the first flow channel system in the flow direction in front of the further radial fan. By the above-described construction of the device according to the invention, it is ensured that the fluid flow applies a particularly high pressure to the underside of the web-shaped material in order to produce on the surface thereof a load-bearing force opposite to the weight force. The fluid flow flowing from above onto the web-shaped material acts on the upper side of the web-shaped material at a significantly lower pressure and primarily serves to equalize the suspended guidance by the total fluid flow.

Alternatively, the invention provides that a first centrifugal fan is provided as the first pressure stage, the fluid flow generated by the first radial fan flows into two flow path systems that act on one side of the sheet-like material, wherein in each of the two flow channel systems another centrifugal fan is provided as a second pressure stage is. With this construction, a safe floating guidance of the web-like material is also possible regardless of its orientation in the device. An optimal use of space in the device according to the invention results from the fact that the first centrifugal fan in the middle of the device in addition to the transported through the device web-shaped material is arranged and the two flow channel systems are arranged point-symmetrical to each other.

In order to produce the very high temperatures in the device, it is provided according to a further embodiment of the invention that the device comprises at least one heating element for heating the fluid flow. This can be arranged within the flow channel system or in the suction channel surrounding the flow channel system. Preferably, the heating element is designed as a jacket radiant tube. This expediently extends transversely to the transport direction of the web-like material and parallel to its surface.

The aforementioned object is achieved according to the invention by a strip float oven for heat treatment of sheet material, in particular metal strips, which comprises at least one device according to one of claims 1 to 9. In several devices, these are arranged one behind the other in the transport direction of the web-shaped material. These can be individual heating zones (with heating elements) and cooling sections (without heating elements).

In the following the invention will be explained in more detail with reference to an illustrative drawing.

Fig. 1

eine Vorrichtung zur schwebenden Führung von Metallbändern in Seitenansicht,

Fig. 2

die Vorrichtung aus Fig. 1 im Querschnitt gemäß der Schnittlinie II-II und

Fig. 3a, b

die erfindungsgemäßen Vorrichtung in zwei Ausführungsformen in stark schematisierter Ansicht.

Show it:

Fig. 1

a device for the floating guidance of metal strips in side view,

Fig. 2

the device off Fig. 1 in cross section according to the section line II-II and

Fig. 3a, b

the device according to the invention in two embodiments in a highly schematic view.

In Fig. 1 a device according to the invention for the floating guidance of sheet material is shown. This comprises a cuboidal housing 1 with an inlet slot 1a and an inlet slot 1b, through which a heavy metal strip B to be treated is guided into or out of the device. When passing through the device, the metal strip B is acted upon by an upper and a lower nozzle field 2, 3 with a treatment gas stream and thus guided floating. In this case, the nozzle fields 2, 3 each comprise a number of nozzle ribs 2a, 3a, from which the gas flows onto the belt B, and each between two nozzle ribs 2a, 3a arranged outflow channels 2b, 3b, via which the gas flows reflected at the belt surfaces in one Suction chamber 4 (see. Fig. 2 ) flow out again. The suction chamber 4 is how out Fig. 2 emerges, arranged on both sides of the floating nozzle fields and extends over the entire length of the device.

In the in the Fig. 1 and 2 The apparatus shown floating metal strip B is heat-treated at the same time by the device. For this purpose, in the present case in the suction chamber 4 above and below the floating nozzle fields 2, 3 each arranged four Mantelstrahlheizrohre 5, 6 formed heating elements which heat the treatment gas after its outflow from the belt surface.

The pressure prevailing in the treatment gas stream, which must be sufficient to float even heavy strips, for example copper strips with a thickness> 2 mm, at very high temperatures (eg 870 ° C), is in the inventive device in several stages through in the flow channel system generates radial fans arranged one behind the other. In the present case, a first centrifugal fan 7 is provided as the first pressure stage, which in the side view of Fig. 1 in the middle of the device next to the metal strip B transported by the device (cf. Fig. 2 ) is arranged. The gas flow generated by the first centrifugal fan 7 flows into two flow channel systems arranged point-symmetrically with respect to one another, as in FIG Fig. 1 shown and described in more detail below.

In detail, the first centrifugal fan 7 is arranged in a spiral housing 8, which divides into a lower half-screw 8a and an upper half-screw 8b. The accelerated in the lower half-screw 8a partial gas flow flows, as in Fig. 1 recognizable, upwards and into the intake manifold 9a of a according to the invention arranged in the upper flow channel system behind the first centrifugal fan 7 further radial fan 9 a. This is preferably designed as a drum rotor. There it is further accelerated in a 360 ° volute casing 10 and flows with further increased pressure from there into a straight channel section 11, from where it is conducted to the opposite end wall of the housing 1. There, the partial gas stream is deflected by 90 ° and passes through the inclined channel section 12 to the nozzle array 2, from where it flows onto the strip surface.

In a very analogous manner, accelerated in the upper half-screw 8b of the volute 8 from the first centrifugal fan 7 partial gas flow flows down into a provided in the lower flow channel in the flow direction behind the first centrifugal fan 7 further radial fan 13, which is also preferably designed as a drum rotor. After the further acceleration and pressure increase, the partial gas stream then flows from there via the flow channel sections 14, 15 into the lower nozzle field 3.

At a gas temperature of, for example, 870 ° C., a gas flow with a pressure of 1500 Pa is generated by the first radial fan 7. This divided into two partial gas streams in the volute 8 gas flow flows through the arranged in the two flow channel systems in the flow direction behind the first centrifugal fan 7 centrifugal fans 9, 13, a further increase in pressure, for example, 3000 Pa. Thus, it is possible in the device according to the invention described herein also to guide heavy belts suspended without the risk of deformation of the fan blades due to a too high selected peripheral speed of a single centrifugal fan.

In the Fig. 3a is a further flow concept for a device according to the invention for the floating guiding of sheet material shown schematically. Here, a gas with the ambient pressure P _{R is} sucked by a first centrifugal fan 16 and accelerated to a flow rate v. At the same time, the pressure in the centrifugal fan 16 is increased by a value ΔP to a value P _o raised. Behind the flow outlet of the centrifugal fan 16, the flow channel system branches into a first and a second flow channel branch 17, 18, wherein a first partial gas flow through the first branch 17 flows directly to a nozzle array D ₁ arranged above the metal strip B to be floated. From there, the partial gas stream with a pressure P _o and a volume flow V _{o is} blown from above onto the metal strip B. A further partial gas flow reaches a further centrifugal fan 19 arranged in the second flow channel branch 18. There, the pressure of the partial gas flow is increased to a value P _u , which is greater than P _o . With this increased pressure P _u and a volume flow v _u , this partial gas stream flows into a nozzle field D ₂ arranged below the metal strip B and from there onto the metal strip B from below Fig. 3a schematically illustrated device thus two partial gas streams are generated, which act on the metal strip B from above and below, the lower partial gas flow having a higher pressure than the upper, to compensate for the downwardly acting weight of the metal strip B.

The in the Fig. 3b schematically illustrated device corresponds to the in the Fig. 1 and 2 illustrated device. In this case, a gas flow with the pressure P _{1 is} generated by a first radial fan 20. Behind the first radial fan 20, the gas stream branches into two partial gas streams, which are supplied in separate flow channel systems 21, 22 to a further radial fan 23, 24. In these radial fans 23, 24 there is a further increase in pressure, so that both partial gas flows with further increased pressure P _o or P _u flow into the nozzle fields D1 and D2 and get from there to the surface of the metal strip B. Here, the pressure P _{u of} the lower partial gas flow greater than or equal to the pressure P _{o of} the upper partial gas flow, while the volume flow v _{u of} the lower partial gas flow is greater than the volume flow v _{o of} the upper partial gas flow.

Claims (7)

1. A device for the flotation guiding of web-shaped material (B), in particular metal strips, having at least one first radial fan (7, 16, 20) and having at least one flow channel system (8a, 10, 11, 12, 8b, 14, 15), which is associated with the at least one first radial fan (7, 16, 20), the at least one first radial fan (7) generating a fluid stream, which is transported through the at least one flow channel system (8a, 10, 11, 12, 8b, 14, 15) to the surface of the web-shaped material (B) for the flotation guiding thereof,
   characterized in that
   at least one further radial fan (9, 13, 19, 23, 24) is situated in the at least one flow channel system (8a, 10, 11, 12, 8b, 14, 15) in the fluid stream direction behind the at least one first radial fan (7) to increase the pressure in the fluid stream,

   a) the device comprising, with essentially horizontal guiding of the web-shaped material (B), the first radial fan (16) and a flow channel system having the further radial fan (19) for applying the fluid stream to the bottom side of the web-shaped material (B), a further flow channel system (17) being provided for application to the top side of the web-shaped material (B), which branches from the first flow channel system in the flow direction in front of the further radial fan (19), or

   b) the first radial fan (7, 20) being provided as the first pressure stage, the fluid stream generated by the first radial fan (7, 20) flowing into two flow channel systems (8a, 10, 11, 12, 21, 8b, 14, 15, 22), which each apply the fluid stream on one side to the web-shaped material (B), the further radial fan (9, 13, 23, 24) being provided as the second pressure stage in each of the two flow channel systems (8a, 10, 11, 12, 21, 8b, 14, 15, 22),

   and the first radial fan (7) being situated centrally in the device adjacent to the web-shaped material (B) transported through the device and the two flow channel systems (8a, 10, 11, 12, 8b, 14, 15) being situated with point symmetry to one another.
2. The device according to Claim 1,
   characterized in that the at least one further radial fan (9, 13) is implemented as a drum rotor.
3. The device according to Claim 1 or 2,
   characterized in that the web-shaped material (B) is guided essentially horizontally through the device.
4. The device according to one of Claims 1 through 3,
   characterized in that the device comprises at least one heating element (5, 6) for heating the fluid stream.
5. The device according to Claim 4,
   characterized in that the heating element is implemented as a radiant heating tube (5, 6).
6. The device according to Claim 5,
   characterized in that the radiant heating tube (5, 6) extends transversely to the transport direction of the web-shaped material (B) and parallel to the surface thereof.
7. A strip flotation furnace for the heat treatment of web-shaped material, in particular metal strips, comprising at least one device according to one of Claims 1 through 6.

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