Flatness-measuring apparatus for measuring the flatness of a metal strip

Abstract

A flatness measuring apparatus for measuring the flatness of a metallic strip, including a measuring roller which has a roller axis and which makes contact with the strip for the measuring the flatness. The measuring roller is connected to a cooling system, using which the measuring roller can be cooled. To ensure that a high degree of measuring accuracy can be maintained even at high temperatures, the cooling system has a nozzle bar that extends parallel to the roller axis. At least one spray nozzle is arranged on the nozzle bar, using which cooling medium can be sprayed on the surface of the measuring roller in a spraying direction. The spraying direction meets a surface section of the measuring roller, and the angle between the spraying direction and the tangent on the measuring roller at the location of the surface section is less than 30?.

Claims

1. A flatness measuring apparatus for measuring the flatness of a metallic strip, comprising a measuring roller which has a roller axis and which is designed to make contact with the strip for the purpose of measuring the flatness, wherein the measuring roller is connected to a cooling system configured to cool the measuring roller, the measuring roller is designed as a deflection roller which is equipped with a sensor system that is configured to measure a radial force exerted by a tensile stress on the deflection roller, the flatness measuring apparatus is part of a hot rolling mill, and the cooling system comprises: a first nozzle bar that extends parallel to the roller axis, wherein a first plurality of spray nozzles is arranged on the first nozzle bar and configured to spray a cooling medium on a surface of the measuring roller in a spraying direction, the spraying direction meets a surface section of the measuring roller, and an angle between the spraying direction and a tangent on the measuring roller at a location of the surface section is less than 30?, a second nozzle bar, which extends parallel to the roller axis and is arranged offset to the first nozzle bar in the circumferential direction of the measuring roller, wherein a second plurality of spray nozzles is arranged on the second nozzle bar and configured to spray the cooling medium on the surface of the measuring roller in the spraying direction, and the angle between the spraying direction and the tangent on the measuring roller at the location of the surface section is less than 30?.

2. The flatness measuring apparatus according to claim 1, wherein the angle is between 0? and 10?.

3. The flatness measuring apparatus according to claim 1, wherein the spray nozzles are flat jet nozzles which emit a cooling medium jet that is at least 4 times as wide as thick.

4. The flatness measuring apparatus according to claim 3, wherein the width of the jet of the flat jet nozzles extends in the direction of the roller axis.

5. The flatness measuring apparatus according to claim 1, wherein the spray nozzles are aligned in such a way that the cooling medium is discharged against a running direction of the measuring roller.

6. The flatness measuring apparatus according to claim 1, wherein the cooling system comprises a housing which encloses the nozzle bar or bars and a circumferential section, at least 180? of the circumference, of the measuring roller.

7. The flatness measuring apparatus according to claim 6, wherein two gaps are formed between the housing and the measuring roller which make the passage of cooling medium difficult.

8. The flatness measuring apparatus according to claim 7, wherein means for delivering a gas are arranged in the region of the gaps, to which a gas flow can be guided in the interior of the housing.

9. The flatness measuring apparatus according to claim 8, wherein the means for delivering a gas comprise slot nozzles which extend in the longitudinal direction of the gaps, wherein the slot nozzles are integrated into the housing in the region of the gaps.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) An exemplary embodiment of the invention is shown in the drawing. In the figures:

(2) FIG. 1 schematically shows a flatness measuring apparatus having a measuring roller and a cooling system, wherein the conveying direction of the strip to be measured (not shown) is perpendicular to the point of the drawing,

(3) FIG. 2 schematically shows a spray nozzle which discharges the cooling medium,

(4) FIG. 3 schematically shows details of the cooling system using which the measuring roller is cooled, wherein the roller axis is perpendicular to the plane of the drawing, and

(5) FIG. 4 schematically shows the flatness measuring apparatus having a housing.

DETAILED DESCRIPTION

(6) In FIG. 1, a flatness measuring apparatus 1 can be seen, which comprises a measuring roller 2, which is used to contact a metallic strip (not shown) The degree of flatness of the strip can thus be determined in a manner known per se. In order that the flatness measuring apparatus 1 can also be used in a hot rolling mill, the measuring roller 2 has to be cooled, for which a cooling system 3 is provided. The cooling system 3 comprises a nozzle bar 4, the longitudinal axis of which is parallel to the roller axis a, as can be seen from FIG. 1. Spray nozzles 5 are arranged at regular intervals on the nozzle bar 4; the spacing is marked by the double arrow in FIG. 1.

(7) Each spray nozzle 5 discharges a jet of cooling medium that is relatively flat. This is illustrated in FIG. 2 The cooling medium is discharged from the spray nozzle 5 in the spray direction b, wherein the spray nozzle 5 is designed as a wide slot nozzle or flat jet nozzle. Accordingly, the cooling medium reaches the surface of the measuring roller 2 having an essentially oval contact area, which has a width B and a thickness D. The contact area that the cooling medium has on the surface of the measuring roller 2 can thus be assigned a longitudinal axis c which is parallel to the roller axis a. The width B is at least four times as large as the (maximum) thickness D, preferably even at least eight times as large.

(8) Details of the cooling system 3 used can be seen in FIG. 3 The measuring roller 2 contacts the strip 12 and rotates in the rotational direction R, wherein its roller axis a is perpendicular to the plane of the drawing in FIG. 3. The cooling system 3 first comprises an (upper) nozzle bar 4 on which the spray nozzles 5 are arranged. Furthermore, it comprises a (lower) nozzle bar 7, on which spray nozzles 5 are likewise arranged. This nozzle bar 7 is optional and is arranged offset in the circumferential direction.

(9) The alignment of the spray nozzles 5 for cooling the surface of the measuring roller 2 is essential. For this purpose, it can be seen in FIG. 3 that the spray nozzles 5 discharge their cooling medium with their spraying direction b at a point or a surface section 6 of the measuring roller 2. If a tangent t is placed on the measuring roller 2 at the point or surface section 6, an angle ? results between the spraying direction b and the tangent t. This angle ? is relatively small and is at most 20?. The preferred range for the angle ? is between 0? and 10?.

(10) The two nozzle bars 4 and 7 are arranged offset in the circumferential direction above the measuring roller 2. For the angular relationships of the impact of the cooling medium on the surface of the measuring roller in the region of the surface section 6, however, the same geometric relationships apply.

(11) In FIG. 4 it can be seen that the flatness measuring apparatus 1 can also have a housing 8 which accommodates the nozzle bars 4 and 7 (not shown here) and encloses the measuring roller over a circumferential section of at least 180?. Small gaps 9 and 10 ensure that only a small amount of cooling medium escapes from the interior of the housing. Liquid leakage can be completely prevented by applying sealing air (as described above).

(12) In the interior of the housing 8, cooling medium 11 collects, which cools the measuring roller 2 over the entire width as it rotates. Meanwhile, it is ensured by the explained geometry in the alignment of the spray nozzles 5 that the measuring function of the measuring roller 2 is not impaired. This is not the case with previously known solutions.

LIST OF REFERENCE SIGNS

(13) 1 flatness measuring apparatus 2 measuring roller 3 cooling system 4 nozzle bar 5 spray nozzle 6 surface section of the measuring roller 7 further nozzle bar 8 housing 9 gap 10 gap 11 accumulated cooling medium 12 volume a roller axis b spraying direction c longitudinal axis of the discharged cooling medium t tangent to the measuring roller B width of the coolant jet D thickness of the coolant jet R rotational direction ? angle