Strip flotation furnace

Abstract

A strip flotation furnace for controlling the temperature of a metal strip has a flotation nozzle bar extending through the furnace transversely to a strip running direction of the strip. The flotation nozzle bar has two opposing first flotation nozzle rows spaced apart by a central region of the flotation nozzle bar. The rows are set up so that corresponding flotation nozzle jets, with a directional component toward the central region, can be generated to provide pressure cushioning for metal strip guiding. A temperature-control nozzle bar extends transversely to and is spaced apart from the flotation nozzle bar along the strip running direction. The temperature-control nozzle bar has two additional opposing temperature-control nozzle rows spaced apart by an additional temperature-control nozzle bar central region. These rows are set up so that corresponding temperature-control nozzle jets, with a directional component opposite to the additional central region, can be generated.

Claims

1. A strip flotation furnace (100) for controlling the temperature of a metal strip (101), the strip flotation furnace (100) comprising: a plurality of flotation nozzle bars (110), each flotation bar of the plurality of flotation bars extending through the strip flotation furnace (100) transversely to a strip running direction (102) of the metal strip (101), wherein each flotation nozzle bar (110) of the plurality of flotation bars has two opposing first rows of flotation nozzles (111), which are spaced apart by a central region (112) of the flotation nozzle bar (110), wherein the rows of flotation nozzles (111) are configured in such a way that corresponding flotation nozzle jets (113), with a directional component in the direction of the central region (112), can be generated in order to provide pressure cushioning for guiding the metal strip (101), a plurality of temperature-control nozzle bars (120) having a smaller nozzle exit area than the flotation nozzle bars, each temperature-control nozzle bar of the plurality of temperature-control nozzle bars extending transversely to a strip running direction (102) of the metal strip (101) and is spaced apart from a corresponding flotation nozzle bar (110) along the strip running direction (102), wherein each temperature-control nozzle bar (120) of the plurality of temperature-control nozzle bars has two opposing additional rows of temperature-control nozzles (121), which are spaced apart by an additional central region (122) of the temperature-control nozzle bar (120), wherein the rows of temperature-control nozzles (121) are configured in such a way that corresponding temperature-control nozzle jets (123), with a directional component in the opposite direction to the additional central region (122), can be generated to temperature control the metal strip as the metal strip is being guided, wherein at least one temperature-control nozzle bar (120) is arranged between two flotation nozzle bars (110) spaced apart in the strip running direction (102), wherein a temperature-control zone (104), by means of which the metal strip (101) may be conveyed, is formed within the strip flotation furnace (100), wherein the flotation nozzle bars (110) are arranged above and below the temperature-control zone (104), wherein upper flotation nozzle bars (110) are arranged so as to be offset from lower flotation nozzle bars (110) in the strip running direction (102), wherein a temperature-control nozzle bar (120) is arranged opposite to a flotation nozzle bar (110) with respect to the temperature-control zone (104), and wherein the lower flotation nozzle bars and lower temperature-control nozzle bars are arranged alternately along the strip running direction and the upper flotation bars and upper temperature-control nozzle bars are arranged alternately along the strip running direction.

2. The strip flotation furnace (100) according to claim 1, wherein at least one row of flotation nozzles comprises a plurality of separate flotation nozzles (201).

3. The strip flotation furnace (100) according to claim 1, wherein at least one row of flotation nozzles comprises at least one slit nozzle which extends transversely to the strip running direction (102).

4. The strip flotation furnace (100) according to claim 1, wherein the strip running direction (102) is defined within a midplane (103) of the strip flotation furnace (100), wherein at least one row of flotation nozzles (111) is designed such that an angle (a) between the flotation nozzle jets (113) and the midplane (103) is 30° to 75°.

5. The strip flotation furnace (100) according to claim 1, wherein the rows of flotation nozzles (111) are designed such that an angle between the flotation nozzle jets (113) of the one row of flotation nozzles (111) and an angle (a) between the flotation nozzle jets (113) of the other row of flotation nozzles (111) differ from one another.

6. The strip flotation furnace (100) according to claim 1, wherein a support region (202) is formed between the rows of flotation nozzles (111) in the central region (112), said support region (202) being configured such that the metal strip (101) may be placed on the support region (202).

7. The strip flotation furnace (100) according to claim 1, wherein the support region (202) comprises nozzle openings (301) for the discharge of fluid.

8. The strip flotation furnace (100) according to claim 1, wherein at least one row of temperature-control nozzles (121) comprises a plurality of separate temperature-control nozzles.

9. The strip flotation furnace (100) according to claim 1, wherein at least one row of temperature-control nozzles comprises at least one slit nozzle (501) which extends transversely to the strip running direction (102).

10. The strip flotation furnace (100) according to claim 1, wherein the strip running direction (102) is defined within a midplane (103) of the strip flotation furnace (100), wherein at least one row of temperature-control nozzles (121) is designed such that an angle (β) between the temperature-control nozzle jets (123) and a normal (n) of the midplane (103) is 0° to 30°.

11. The strip flotation furnace (100) according to claim 1, wherein the rows of temperature-control nozzles (121) are designed such that an angle between the temperature-control nozzle jets (123) of the one row of temperature-control nozzles (121) and an angle (β) between the temperature-control nozzle jets (123) of the other row of temperature-control nozzles differ from one another.

12. The strip flotation furnace (100) according to claim 1, wherein an open channel (401) directed towards the metal strip (101) is formed between the rows of temperature-control nozzles (121).

13. The strip flotation furnace (100) according to claim 1, wherein the temperature-control nozzle bars (120) are arranged merely above or below a temperature-control zone (104) through which the metal strip (101) can be conveyed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Below, for further explanation and better understanding of the present invention, exemplary embodiments will be described in further detail making reference to the enclosed drawings. These show:

(2) FIG. 1 a schematic representation of a strip flotation furnace according to an exemplary design of the present invention.

(3) FIG. 2 a sectional representation of a flotation nozzle bar according to an exemplary embodiment of the present invention.

(4) FIG. 3 a perspective representation of the flotation nozzle bar from FIG. 2.

(5) FIG. 4 a sectional representation of a temperature-control nozzle bar according to an exemplary embodiment of the present invention.

(6) FIG. 5 a perspective representation of the temperature-control nozzle bar from FIG. 4.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

(7) Equal or similar components are provided with equal reference numbers in different figures. The representations in the figures are schematic.

(8) FIG. 1 shows a schematic representation of a strip flotation furnace 100 for controlling the temperature of a metal strip 101 according to an exemplary design of the present invention. The strip flotation furnace 100 has a flotation nozzle bar 110, which extends through the strip flotation furnace 100 transversely to a strip running direction 102 of the metal strip 101, wherein the flotation nozzle bar 110 has two opposing first rows of flotation nozzles 111, which are spaced apart by a central region 112 of the flotation nozzle bar 110. The rows of flotation nozzles 111 are set up in such a way that corresponding flotation nozzle jets 113, with a directional component in the direction of the central region 112, can be generated in order to provide pressure cushioning for guiding the metal strip 101. The strip flotation furnace 100 also has a temperature-control nozzle bar 120, which extends transversely to a strip running direction 102 of the metal strip 101 and is spaced apart from the flotation nozzle bar 110 along the strip running direction 102, wherein the temperature-control nozzle bar 120 has two additional opposing rows of temperature-control nozzles 121, which are spaced apart by an additional central region 122 of the temperature-control nozzle bar 120. The rows of temperature-control nozzles 121 are set up in such a way that corresponding temperature-control nozzle jets 123, with a directional component in the opposite direction to the additional central region 122, can be generated.

(9) The strip flotation furnace 100 is configured to floatingly convey the metal strip 101 along a conveying direction and/or along the strip running direction 102. At the same time, the strip flotation furnace is 100 configured for bringing the metal strip 101 to a desired temperature, i.e. to heat or cool it. The strip flotation furnace 100 comprises flotation nozzle bars 110 and temperature-control nozzle bars 120 for this purpose.

(10) The metal strip 101 is floatingly guided through a temperature-control zone 104 of the strip flotation furnace 100. Within the temperature-control zone 104, there is a midplane 103 which, in general, corresponds to a horizontal plane. The strip running direction 102 is defined within the midplane 103, such that an entry of the strip flotation furnace 100 and an exit of the strip flotation furnace 100 are present along the strip running direction 102. In other words, the metal strip 101 is conveyed from an entry of the strip flotation furnace 100 to an exit of the strip flotation furnace 100 along the strip running direction 102.

(11) The flotation nozzle bars 110 extend transversely, in particular at 90°, to the strip running direction 102. Corresponding rows of flotation nozzles 111, which are spaced apart by a central region 112 of the flotation nozzle bar 110, are arranged at the two opposing longitudinal sides of the flotation nozzle bar 110. With reference to the strip running direction 102, a flotation nozzle bar 110 thus comprises a front row of flotation nozzles 111 and a rear row of flotation nozzles 111.

(12) The rows of flotation nozzles 111 are formed and configured such that flotation nozzle jets 113 can be generated which may be streamed into the temperature-control zone 104 of the strip flotation furnace 100 in a predetermined and precisely defined direction with respect to the midplane 103. The rows of flotation nozzles 111 are formed such that the flotation nozzle jets 113 of the corresponding rows of flotation nozzles 111 each flow into the temperature-control zone 104 in the direction of the central region 112, i.e. the middle of the flotation nozzle bar 100. In other words, the flotation nozzle jets 113 each have a directional component which is directed in the direction of the central region 112 of the flotation nozzle bar 110 and correspondingly not outwardly, i.e. in the opposite direction to the central region 112. Hence, the flotation nozzle jets 113 are bundled in the center, i.e. in a region above the central region 112, and a strong pressure cushioning is generated in the temperature-control zone 104 above the central region 112 of the flotation nozzle bar 110. This results in a high load capacity for carrying and/or deflecting/adjusting the position of the metal strip 101 being possible.

(13) A temperature-control nozzle bar 120 extend transversely, in particular at 90°, to the strip running direction 102. In particular, the temperature-control nozzle bar 120 extends at least across the entire width of the metal strip 101. Corresponding rows of temperature-control nozzles 121, which are spaced apart by a central region 112 of the temperature-control nozzle bar 120, are arranged at the two opposing longitudinal sides of the temperature-control nozzle bar 120. With reference to the strip running direction 104, a temperature-control nozzle bar 120 thus comprises a front row of temperature-control nozzles 121 and a rear row of temperature-control nozzles 121.

(14) The rows of temperature-control nozzles 121 are formed and configured such that temperature-control nozzle jets 123 can be generated which may be streamed into the temperature-control zone 104 of the strip flotation furnace in a predetermined and precisely defined direction with respect to the midplane 103. The rows of temperature-control nozzles 121 according to the present invention are, in particular, formed such that the temperature-control nozzle jets 123 of the corresponding rows of temperature-control nozzles 121 each flow into the temperature-control zone 104 in the opposite direction of the additional central region 122, i.e. away from the center of the temperature-control nozzle bar 120. In other words, the temperature-control nozzle jets 123 each have a directional component which is directed in the opposite direction of the additional central region 122 of the temperature-control nozzle bar 120 and correspondingly not inwardly, i.e. in the direction towards the additional central region 122. Hence, the temperature-control nozzle jets 123 are not bundled in the additional center 122, i.e. in a region above the additional central region 122, but the temperature-control nozzle jets 123 distribute in the surrounding of the corresponding temperature-control nozzle bar 120.

(15) Hence, as compare to the flotation nozzle bars 120, no strong pressure cushioning is created in the temperature-control zone 104. Due to this, a high volume flow of temperature-control fluid may be streamed in through the rows of temperature-control nozzles 123 without generating a control of the pressure cushioning, which unintentionally deflects the position of the metal strip 101. At the same time, the high volume flow creates a high temperature-control effect of the metal strip 101 by means of the temperature-control fluid.

(16) The strip flotation furnace 100 of FIG. 1 comprises a plurality of flotation nozzle bars 110 and a plurality of temperature-control nozzle bars 120. The number depends on the desired temperature-control performance and the conveying path of the metal strip 101 in the strip flotation furnace 100.

(17) In the exemplary embodiment, at least one temperature-control nozzle bar 120 is arranged between two flotation nozzle bars 110 spaced apart in the strip running direction 102 (which are both located below or above the metal strip 101 and/or the temperature-control zone 104). The flotation nozzle bars 110 and the temperature-control nozzle bars 120 are arranged above and below the temperature-control zone.

(18) The upper flotation nozzle bars 110 are arranged so as to be offset from the lower flotation nozzle bars 110 in the strip running direction 102. Thus, along a connection line defined perpendicularly to the midplane 103 of the strip flotation furnace 100, no upper and lower flotation nozzle bars 110 lie together on this connection line. The lower flotation nozzle bars 110 and the lower temperature-control nozzle bars 120 are arranged alternately, i.e. in turns, along the strip running direction 102. Accordingly, the upper flotation nozzle bars 110 and the upper temperature-control nozzle bars 120 are arranged alternately, i.e. in turns, along the strip running direction 102. Moreover, the flotation nozzle bars 110 and the temperature-control nozzle bars 120 are arranged such that on the connection line described above, which is formed perpendicularly to the midplane 103, one (upper or lower) temperature-control nozzle bar 120 and one (correspondingly lower or upper) flotation nozzle bar 110 are arranged on opposite sides of the temperature-control zone 104, in each case. This results in that a pressure cushioning of the flotation nozzle bars 110 is always formed only on one side of the metal strip 101, i.e. at the top or at the bottom, and a further pressure cushioning of a further flotation nozzle bar 110 is spaced apart in the strip running direction 102 and is formed on the other side of the metal strip 101. This allows the metal strip 101 to assume a sinusoidal shape in the longitudinal direction, i.e. in the strip running direction 102, thus reducing the risk of twisting of the metal strip 101.

(19) Moreover, a temperature-control nozzle bar 120 is arranged opposite to a flotation nozzle bar 110 with respect to the temperature-control zone 104. Since the flotation nozzle bars 110 create a stronger pressure cushioning and the temperature-control nozzle bars 120 apply a higher temperature-control effect, thus, a sinusoidal shape of the metal strip 101 may be generated and, at the same, a good temperature-control effect across the entire length of the metal strip 101 may be provided.

(20) FIG. 2 shows a sectional representation and FIG. 3 shows a perspective representation of a flotation nozzle bar 110 according to an exemplary embodiment of the present invention.

(21) The rows of flotation nozzles 111 each comprise a plurality of separate flotation nozzles 201. The individual flotation nozzles 201 may have a rectangular exit cross section.

(22) A row of flotation nozzles 111 is designed such that an angle α between the flotation nozzle jets and the midplane 103 is 45°. The flotation nozzles 201 of the rows of flotation nozzles are configured such that at their exit the flotation nozzle jets 113 flow radially in a predetermined direction in the direction of the temperature-control zone 104. After having left the flotation nozzles 201, the flotation nozzle jets 113 are deflected within the temperature-control zone 104 according to the flow characteristics (see flow arrows in FIG. 1). Hence, a particularly strong pressure cushioning is generated in the central region 112 of the flotation nozzle bar 110.

(23) A support region 202 is formed between the rows of flotation nozzles 111 in the central region 112, said support region being configured such that the metal strip 101 may be placed on the support region 202. In particular, the support region 202 projects further into the temperature-control zone 104 than a corresponding nozzle exit of the corresponding rows of flotation nozzles 111. During a starting process or in case of a fault of the strip flotation furnace 100, the metal strip 101 may thus gently be placed on the support region 202.

(24) The support region 202 comprises nozzle openings 301 for the discharge of fluid. In particular, a perforated plate, which has a plurality of nozzle holes 301, is arranged at the support region 202.

(25) FIG. 4 shows a sectional representation and FIG. 5 shows a perspective representation of a temperature-control nozzle bar 120 according to an exemplary embodiment of the present invention.

(26) The temperature-control nozzle bar 120 comprises at least one slit nozzle 501 which extends transversely to the strip running direction 102. The temperature-control nozzles are narrow and assume a finger-like shape in cross-section. The individual temperature-control nozzles may have a rectangular exit cross section. An angle β is approximately 15° between the temperature-control nozzle jets 123 and the normal n of the midplane. Thus, the temperature-control nozzle jets 123 stream relatively directly onto the metal strip 101, such that impact jets are enabled. By means of impact jets, efficient heat exchange between the metal strip 102 and the temperature-control fluid may be enabled.

(27) An open channel 401 directed towards the metal strip 101 and/or the temperature-control zone 104 is formed between the rows of temperature-control nozzles 121. The open channel 401 results in that the temperature-control fluid, which flows back from the metal strip 101 and, in particular, bounces back due to the impact jetting, may flow into the open channel 401 and be discharged. Thus, the pressure, which is generated by the temperature-control nozzle jets is reduced, since the volume between the temperature-control nozzle bars 120 and the metal strip 101 is enlarged by means of the open channel 401. Stiffening struts 402 are provided between the rows of temperature-control nozzles 121 so as to provide sufficient stability despite the open channel 401.

(28) Additionally, it should be noted that “comprising” does not preclude other elements or steps, and “one” or “a” does not preclude a plurality. Moreover, it should be noted that features or steps that have been described with reference to one of the above exemplary embodiments may also be used in combination with other features or steps of other exemplary embodiments described above. Reference numbers in the claims are not to be regarded as a limitation.

LIST OF REFERENCE NUMBERS

(29) 100 Strip flotation furnace 101 Metal strip 102 Strip running direction 103 Midplane 104 Temperature-control zone 110 Flotation nozzle bar 111 Rows of flotation nozzles 112 Central region 113 Flotation nozzle jets 120 Temperature-control nozzle bar 121 Row of temperature-control nozzles 122 Further central region 123 Temperature-control nozzle jets 201 Flotation nozzles 202 Support region 301 Nozzle openings 401 Open channel 402 Stiffening strut 501 Slit nozzle α Angle of flotation nozzle jets β Angle of temperature-control nozzle jets n Normal