Cleaning rolling stock during cold rolling of the rolling stock

Abstract

A method for cleaning rolling stock (5) during cold rolling of the rolling stock (5) in a tandem mill (1) which includes a plurality of mill stands (7, 9). The rolling stock (5) is moved through the tandem mill (1) in a direction of movement (3) and a cleaning liquid (26) is sprayed onto the rolling stock (5) between two roll stands (7, 9) in a spraying direction having a component opposite to that of the direction of movement (3).

Claims

1. A method for cleaning a workpiece during cold rolling of the workpiece in a tandem mill having a plurality of mill stands, the workpiece having a first edge and a second edge opposite the first edge, the method comprising: moving the workpiece through the tandem mill in one direction of rolling; and spraying a cleaning liquid from a plurality of nozzles of a spraying bar between two of the mill stands onto the workpiece in a spraying direction having a component that is counter to the direction of rolling, no spraying direction of each of the plurality of nozzles being oriented to cross each other, and pivoting the spraying bar to adjust a spraying angle of the plurality of nozzles between the spraying direction and a surface of the workpiece, wherein each nozzle of the plurality of nozzles is either closer to the first edge of the workpiece and farther from the second edge of the workpiece, or closer to the second edge of the workpiece and farther from the first edge of the workpiece, wherein each nozzle of the plurality of nozzles is oriented to spray the cleaning liquid in a respective spray direction toward the edge of the workpiece that is closer thereto, and none of the nozzles from the plurality of nozzles is oriented to spray the cleaning liquid in a respective spray direction toward the edge of the workpiece that is farther thereto.

2. The method as claimed in claim 1, wherein the cleaning liquid is sprayed onto the workpiece between the first mill stand and the second mill stand of the plurality of mill stands.

3. The method as claimed in claim 1, further comprising spraying the cleaning liquid onto the workpiece between the second mill stand and the third mill stand of the plurality of mill stands.

4. The method as claimed in claim 1, further comprising using an emulsion as the cleaning liquid.

5. The method as claimed in claim 1, further comprising using water as the cleaning liquid.

6. The method as claimed in claim 1, further comprising spraying the cleaning liquid onto the workpiece at a pressure of between 6 and 100 bar.

7. The method as claimed in claim 1, further comprising varying the spraying direction of the cleaning liquid across a width of the workpiece at right angles to the direction of rolling.

8. The method as claimed in claim 1, further comprising spraying the cleaning liquid on an upper surface and a lower surface of the workpiece.

9. A method for cleaning a workpiece during opposite direction reversing cold rolling of the workpiece in a mill stand, the workpiece having a first edge and a second edge opposite the first edge, the method comprising: moving the workpiece through the mill stand in alternately opposite directions of rolling the workpiece in a plurality of rolling passes; and between two of the rolling passes, spraying a cleaning liquid, from a plurality of nozzles, the plurality of nozzles being arranged along only a single continuous line starting at the first edge and ending at the second edge of the workpiece, onto the workpiece in a spraying direction having a component that is counter to the direction of rolling, no spraying direction of each of the plurality of nozzles being oriented to cross each other, wherein each first nozzle of the plurality of nozzles is closer to the first edge of the workpiece and farther from the second edge of the workpiece, wherein each second nozzle of the plurality of nozzles is closer to the second edge of the workpiece and farther from the first edge of the workpiece, wherein each nozzle of the plurality of nozzles is oriented to spray the cleaning liquid in a respective spray direction toward the edge of the workpiece that is closer thereto, and none of the nozzles from the plurality of nozzles that is arranged along the single continuous line is oriented to spray the cleaning liquid in a respective spray direction toward the edge of the workpiece that is farther thereto.

10. The method as claimed in claim 9, further comprising spraying the cleaning liquid onto the workpiece between a first rolling pass and a second rolling pass.

11. The method as claimed in claim 9, further comprising spraying the cleaning liquid onto the workpiece between a second rolling pass and a third rolling pass.

12. A tandem mill for cold rolling of a workpiece that is being moved in one direction of rolling through the tandem mill, the tandem mill comprising: a plurality of mill stands arranged in tandem along the one direction of rolling; and at least one spraying bar disposed between two of the mill stands, the spraying bar being pivotable to permit adjustment of a spraying angle between a spraying direction and a surface of the workpiece, the spray bar having a plurality of nozzles from which a cleaning liquid is sprayed onto the workpiece in a spraying direction having a component that is counter to the direction of rolling, no spraying direction of each of the plurality of nozzles being oriented to cross each other, wherein each nozzle of the plurality of nozzles is either closer to a first edge of the workpiece and farther from a second edge of the workpiece, or closer to the second edge of the workpiece and farther from the first edge of the workpiece, wherein each nozzle of the plurality of nozzles is oriented to spray the cleaning liquid in a respective spray direction toward the edge of the workpiece that is closer thereto, and none of the nozzles from the plurality of nozzles is oriented to spray the cleaning liquid in a respective spray direction toward the edge of the workpiece that is farther thereto.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a section of a first exemplary embodiment of a tandem mill,

(2) FIG. 2 shows a section of a second exemplary embodiment of a tandem mill,

(3) FIG. 3 shows a plan view of a first exemplary embodiment of a spraying bar between two mill stands,

(4) FIG. 4 shows a side view of the spraying bar illustrated in FIG. 3 between two mill stands,

(5) FIG. 5 shows a plan view of a second exemplary embodiment of a spraying bar between two mill stands,

(6) FIG. 6 shows a side view of the spraying bar shown in FIG. 5 between two mill stands.

DESCRIPTION OF EMBODIMENTS

(7) Corresponding parts are provided with the same reference characters in the figures.

(8) FIG. 1 schematically illustrates a section of a first exemplary embodiment of a tandem mill 1 for cold rolling a workpiece 5, in this case a metal strip, that is moved in one direction of rolling 3 through the tandem mill 1.

(9) The tandem mill 1 comprises a plurality mill stands 7, 9, of which only two are shown in FIG. 1. In particular, the two mill stands 7, 9 shown can be a first and a second mill stand 7, 9 or a second and a third mill stand 7, 9 of the tandem mill 1. Each mill stand 7, 9 has two work rolls 11 disposed one above the other and separated by a roll gap through which the workpiece 5 is passed and thereby rolled. Each mill stand 7 also has a backup roll 13 for each work roll 11.

(10) The tandem mill 1 additionally comprises an emulsion system 15 for dispensing an emulsion 16 onto the work roll 11 and the workpiece 5. The emulsion 16 generally contains water, rolling oil and an emulsifier in order to make the rolling oil miscible with the water. The emulsion 16 may also have other constituents, e.g. at least one antioxidant, a wear protection additive and/or a corrosion protection additive. The emulsion 16 is dispensed, on the entry side of the moving strip 5, into the region of the roll gap of each mill stand 7, 9, onto the upper side and lower side of the workpiece 5 and the two work rolls 11 of the mill stand 7, 9 and, on the exit side of the strip, is dispensed onto the two work rolls 11 of the mill stand 7, 9. The term entry side denotes the side of a mill stand 7, 9 from which the workpiece 5 is fed into the mill stand 7, 9, and the term exit side denotes the side of the mill stand 7, 9 opposite the entry side.

(11) The emulsion system 15 has an emulsion tank 17 for storing emulsion 16 to be dispensed and, for each mill stand 7, 9, has a collecting vessel 19 for collecting emulsion 16 that drips off the mill stand 7, 9. The emulsion system 15 also has pipework wherein emulsion 16 is conveyed from the collecting vessels 19 into the emulsion tank 17 and from the emulsion tank 17 to the mill stands 7.

(12) Two spraying bars 21, 23 for cleaning the workpiece 5 are disposed between the first mill stand 7 and the second mill stand 9, including an upper spraying bar 21 disposed above the workpiece 5 and lower spraying bar 23 disposed below the workpiece 5.

(13) Each spraying bar 21, 23 has a plurality of spray nozzles 25 from which a cleaning liquid 26 can be sprayed onto the workpiece 5 in a spraying direction having a spray component that is counter to the direction of rolling 3. In this exemplary embodiment, the sprayed cleaning liquid 26 is a filtered emulsion 16 which is supplied to the spraying bars 21, 23 from the emulsion system 15 via a filter 27 and a pump 29 in each case. The filters 27 are used to separate contaminants, particularly metal particles abraded from the workpiece 5 and the work rolls 11, from the emulsion 16. The pumps 29 each produce a pressure of between 6 and 100 bar at which the cleaning liquid 26 is sprayed onto the workpiece 5. The vertical distance of the nozzles 25 from the workpiece 5 is e.g. approximately 20 cm. Examples of spraying bars 21, 23 will be described in more detail below with reference to FIGS. 3 to 6.

(14) Similarly to the spraying bars 21, 23 shown in FIG. 1, spraying bars 21, 23 can also be disposed between other mill stands 7, 9 of the tandem mill 1.

(15) FIG. 2 schematically illustrates a section of a second exemplary embodiment of a tandem mill 1 for cold rolling a workpiece 5, in this case metal strip, moved in one direction of rolling 3 through the tandem mill 1. This exemplary embodiment differs from the exemplary embodiment shown in FIG. 1 only in that the spraying bars 21, 23 are not fed from the emulsion system 15 but are fed from a separate cleaning system 31 which supplies the spraying bars 21, 23 with a cleaning liquid 26 that is different from the emulsion 16 of the emulsion system 15.

(16) The cleaning liquid 26 in this exemplary embodiment is, for example, an emulsion similar to the emulsion 16 of the emulsion system 15, but the composition is different from that of the emulsion 16 of the emulsion system 15 to improve the cleaning effect. Alternatively, the cleaning liquid 26 is water, for example.

(17) The cleaning system 31 comprises a cleaning liquid tank 33 for storing cleaning liquid 26 to be supplied to the respective spraying bars 21, 23 via a pump 29 and optionally via a filter 27.

(18) FIGS. 3 and 4 schematically illustrate a first exemplary embodiment of a spraying bar 21 that is between two mill stands 7, 9. FIG. 3 shows a plan view of the spraying bar 21, the workpiece 5 and the mill stands 7, 9, and FIG. 4 shows a side view of the spraying bar 21, the workpiece 5 and the work rolls 11 of the mill stands 7, 9, with only one spray jet being shown in FIG. 4 for the sake of clarity.

(19) The spraying bar 21 extends above the workpiece 5 between opposite edge regions 35, 37 of the workpiece 5. The spraying bar 21 has two spraying arms each extending from the center of the spraying bar 21 toward one of the edge regions 35, 37 and forming an angle with each other, so that the spraying bar 21 is V-shaped, wherein the apex of the V faces the mill stand 7 through which the workpiece 5 initially passes. The nozzles 25 of the spraying bar 21 are disposed on an outlet side of the spraying bar 21, in which outlet side faces the mill stand 7 through which the workpiece 5 initially passes. Each nozzle 25 is directed to spray cleaning liquid 26 onto the workpiece 5 in a spraying direction having a component counter to the direction of rolling.

(20) FIGS. 5 and 6 schematically illustrate a second exemplary embodiment of a spraying bar 21 between two mill stands 7, 9. Similarly to FIG. 3, FIG. 5 shows a plan view of the spraying bar 21, the workpiece 5 and the mill stands 7, 9, and, similarly to FIG. 4, FIG. 6 shows a side view of the spraying bar 21, the workpiece 5 and the work rolls 11 of the mill stands 7, 9.

(21) In contrast to the first exemplary embodiment shown in FIGS. 3 and 4, the spraying bar 21 in the second embodiment does not extend in a V-shaped manner but extends in a straight line above and across the workpiece 5 between opposite edge regions 35, 37 of the workpiece 5. The nozzles 25 of the spraying bar 21 are again disposed on an outlet side of the spraying bar 21, which outlet side faces the mill stand 7 through which the workpiece 5 initially passes. Each nozzle 25 applies cleaning liquid 26 to the workpiece 5 in a spraying direction having a component counter to the direction of rolling 3.

(22) In the two exemplary embodiments of a spraying bar 21 shown in FIGS. 3 to 6, the spraying direction of each nozzle 25 has a component which is directed at the edge region 35, 37 closest to the respective nozzle 25. In the exemplary embodiment shown in FIGS. 3 and 4, this is achieved by the V-shape of the spraying bar 21, wherein the cleaning liquid 26 can be delivered perpendicular to the line of the respective leg of the spraying bar. In the exemplary embodiment shown in FIGS. 5 and 6 this is achieved by the orientation of the nozzles 25 of the spraying bar 21. The exemplary embodiment shown in FIGS. 3 and 4 therefore allows a simpler arrangement of the nozzles 25 in the spraying bar 21 compared to the exemplary embodiment shown in FIGS. 5 and 6, whereas the exemplary embodiment shown in FIGS. 5 and 6 has a simpler geometric form of the spraying bar 21 itself than the exemplary embodiment shown in FIGS. 3 and 4.

(23) In both the exemplary embodiments of a spraying bar 21 shown in FIGS. 3 to 6, the spraying bar 21 may also be pivotally mounted so that the spraying angle 39 between the spraying direction and the surface of the workpiece 5 sprayed with the cleaning liquid 26 can be adjusted.

(24) The nozzles 25 are e.g. flat fan nozzles, each having a spray profile that widens out from the nozzle 25 to the workpiece 5. Alternatively, the nozzles 25 can be implemented as full jet nozzles having a spray profile of essentially constant cross-section.

(25) The inventive cleaning of the workpiece 5 is inexpensive to acquire and is easy to connect to existing plant automation, as no other facilities are necessary for connecting the spraying bars 21, 23 apart from one additional pump 29, possibly a filter 27 for removing contaminants and one control valve for each spraying bar 21, 23 or group of spraying bars. In addition, as the spraying bars 21, 23 spray the cleaning liquid 26 onto the workpiece 5 under relatively high pressure, only a much smaller amount of cleaning liquid 26, e.g. approximately 500 l/min per inter-stand region, is applied to the workpiece 5 compared to emulsion 16 from the emulsion system 15 (e.g. 6000 l/min per stand 7, 9), so that the cooling behavior of the workpiece 5 is not significantly affected by the additional spraying bars 21, 23 and therefore complex control of the quantities of cleaning liquid delivered by the spraying bars 21, 23 is unnecessary. The spraying bars 21, 23 are simply connected with a constant throughput in terms of flow rate and volume. For the above reasons, the inventive cleaning of the workpiece 5 is also suitable as an inexpensive retrofit solution for existing tandem mills 1.

(26) Although the invention has been illustrated and described in detail by preferred exemplary embodiments, the invention is not limited by the examples disclosed and other variations will be apparent to persons skilled in the art without departing from the scope of protection sought for the invention.

LIST OF REFERENCE CHARACTERS

(27) 1 tandem mill 3 direction of rolling 5 workpiece 7, 9 mill stand 11 work roll 13 backup roll 15 emulsion system 16 emulsion 17 emulsion tank 19 collecting vessel 21, 23 spraying bars 25 nozzle 26 cleaning liquid 27 filter 29 pump 31 cleaning system 33 cleaning tank 35, 37 edge region 39 spraying angle