Method and apparatus for continuous treatment of a metal strip

Abstract

The invention relates to a device for continuous treatment of a metal strip (1), in particular a metal strip consisting of aluminum or an aluminum alloy, or consisting of a non-ferrous metal or a non-ferrous metal alloy, said device comprising at least one temperature control device (2) through which the metal strip (1) is guided in a floating manner, and comprising at least one strip position regulation unit (7), by means of which the position of the metal strip (1) can be controlled or regulated on the belt movement plane (E) and transversely to the strip running direction (B), wherein the temperature control device (2) has at least one entry-side heating section (3) and an exit-side cooling section (4). The invention is characterised in that the strip position regulation unit (7) that works in a contactless manner has at least one contactless strip position detection element (12) and at least one linear motor (13) and is arranged within the heating section (3) or between the heating section (3) and the cooling section (4).

Claims

1. In an apparatus for continuously treating a metal strip made of aluminum or an aluminum alloy or of nonferrous metal or a nonferrous metal alloy, the apparatus having at least one temperature adjuster through which the metal strip is passed in a suspended form in a strip-travel direction, and at least one strip-position adjuster that can control with or without feedback the position of the metal strip in a plane of travel of the strip and transversely to the strip-travel direction, the temperature adjuster having at least one heating zone at an intake end and one cooling zone at an output end, the improvement wherein the strip-position adjuster operates by a noncontact method and comprises: at least one noncontact strip-position detector, at least one inductive linear actuator having a stator coil generating an alternating electromagnetic field that is effective transversely of the strip-travel direction and in the plane on the strip, and the strip-position adjuster is inside the heating zone or between the heating zone and the cooling zone.

2. The apparatus according to claim 1, wherein the heating zone has a plurality of heating subzones, and the noncontact strip-position adjuster and the strip-position detector are between two heating subzones.

3. The apparatus according to claim 1 having a plurality of the strip-position adjusters, wherein a space between a strip-deflecting roller upstream of the heating zone and the immediately downstream strip-position adjuster or between two strip-position adjusters positioned downstream of the other in the strip-travel direction between two linear actuators is less than 100 m.

4. The apparatus according to claim 1, wherein the linear actuator is above or below the strip.

5. The apparatus according to claim 1, wherein the linear actuator has a transverse dimension that is at least equal to a transverse width of a strip of maximum strip width.

6. The apparatus according to claim 1, wherein the linear actuator has a vertical open spacing of at least 80 mm.

7. The apparatus according to claim 1, wherein the linear actuator is water-cooled.

8. The apparatus according to claim 1, wherein the strip-position detector is an inductive, capacitive, optical, or radar sensor.

9. The apparatus according to claim 1, wherein the furthest upstream strip-position adjuster is spaced in the heating zone downstream from the furthest downstream strip-deflecting roller upstream of the heating zone at least ten times a width of the strip.

10. In a method of continuously treating a metal strip using an apparatus according to claim 1 and in which the metal strip is guided in suspension through the heating zone and the cooling zone for thermal treatment, the improvement comprising the step of: adjusting a position of the metal strip with or without feedback by at least one strip-position adjuster that operates in a noncontact manner and is in the heating zone or between the heating zone and the cooling zone.

11. The method according to claim 10, wherein the position is adjusted by the steps of: measuring a deviation in the actual position of a central axis of the metal strip from an ideal central position aligned with an ideal central axis of the metal strip, generating correction signals from the deviation, and moving the metal strip by the linear actuator or motors into the ideal position.

12. The method according to claim 10, wherein the strip-position adjuster is between two heating subzones.

13. The method according to claim 10, wherein the strip-position adjuster or its strip-position detector is in an area of the heating zone where the temperature of the metal strip is more than 300 C.

14. The method according to claim 11, wherein the actual position is measured upstream of the linear actuators or downstream of the linear actuators or at the linear actuators.

15. The method according to claim 10, wherein the force exerted on the strip by the linear actuators is controlled across the strip-travel direction in proportion to the measured deviation of the strip from an ideal centered position.

16. The method according to claim 10, wherein a correction using the linear actuators is not performed when there is a deviation in the actual position from an ideal position within a tolerance range.

Description

(1) The invention is explained in greater detail below on the basis of a drawing that illustrates only one embodiment in which:

(2) FIG. 1 is a simplified schematic diagram showing a strip-treatment apparatus,

(3) FIG. 2 an enlarged detail of the apparatus of FIG. 1, and

(4) FIG. 3 is a (simplified) top view of a metal strip inside the apparatus according to FIG. 2.

(5) The figures illustrate in simplified views a strip-treatment apparatus for continuously treating a metal strip 1, namely a thermal treatment. This apparatus has a temperature adjuster 2 that is a suspended-strip furnace. The metal strip passes through this suspended-strip furnace 2 in a noncontact operation, in that nozzles 8 and 9 are acted upon by a corresponding pressure, for example superatmospheric pressure. The suspended-strip furnace 2 has a heating zone 3 at the upstream intake end and a cooling zone 4 at the downstream output end. The heating zone is comprised of a plurality of heating subzones 3, while the cooling zone is comprised of a plurality of cooling subzones 4, the individual subzones 3 and 4 being controllable individually or separately. The heating of the metal strip 1 is usually carried out with the help of air in the heating subzones 3 so that the nozzles 8 and 9 can also assume the function of temperature control in addition to their support function. The cooling usually also takes place with air or a combination of air and water in the cooling subzones 4. In the case of an annealing line for aluminum strips for automotive body purposes, the ideal temperature (of the metal strips) in the heating subzone is about 550 C. to 570 C., for example. Consequently, the heating subzones 3 form heating subzones and holding subzones. FIG. 2 shows that the upper and lower nozzles 8 and 9 are offset transversely to the plane E of travel of the strip with a (vertical) nozzle spacing. A plurality of the furnace subzones, for example the heating subzones 3 and the cooling subzones 4 succeed one another in a strip-travel direction B, and the temperature of the subzones 3 and/or 4 can each be controlled thermally independently of one another. Within one furnace subzone 3, 4, the upper nozzles 8 are connected to an upper nozzle box 10 and the lower nozzles 9 are connected to a lower nozzle box 11. As a rule a separate fan is provided for each of these nozzle boxes 10 and 11, and the fans communicate with the nozzles 8 and 9 by distribution passages. Details of these designs are basically known.

(6) FIG. 1 also shows that the installation has a tension roller set 5 at the intake end with which the strip tension is reduced, for example to a specific strip tension of 0.5 to 1 MPa. Downstream of the suspended-strip furnace 2 and/or downstream of the furthest downstream cooling subzone, a tension roller set 6 at the output end increases the strip tension to the usual line level of specifically 10 to 20 mPa, for example, customary for that line. Because of the low specific strip tension within the suspended-strip furnace, it is necessary to center the metal strip 1 with the help of a strip-position adjuster 7 and/or to keep it there.

(7) Consequently, the apparatus according to the invention has one or more of the strip-position adjusters 7 that can control the position of the metal strip in the plane E of travel of the strip and/or transversely to the travel direction B of the strip with or without feedback.

(8) According to the invention, at least one strip-position adjuster 7 is in the heating zone 3. This is illustrated in FIG. 2. The strip-position adjuster 7 operates without noncontact. It has at least one noncontact strip-position detector 12 and at least one linear actuator 13, and both the strip-position detector 12 and the linear actuator 13 are inside the heating zone 3 in this embodiment. The figures show that the strip-position adjuster 7 is between two heating subzones 3 of which one is positioned directly downstream of the other. The two heating subzones 3 are at a spacing from one another in the strip-travel direction, and the strip-position adjuster 7 is in the gap. In the embodiment according to FIG. 2, a linear actuator 13 is above the strip and beneath the strip, in that the stator 13 of the linear actuator 13 because the armature of the linear actuator 13 is formed by the metal strip itself.

(9) It can be seen in FIG. 3 that, with the help of the linear actuator 13, a force is created acting parallel to a plane E of travel of the strip and transversely and/or orthogonally to the travel direction B of the strip. FIG. 3 shows the ideal central axis 14 of the strip 1 that for example corresponds to the central axis of the strip treatment machine. Furthermore, FIG. 3 indicates as an example the actual central axis 15, namely for the case when the actual central axis 15 is offset from the ideal central axis 14 by a deflection V of the strip. With the help of the strip-position detector 12, the position of the actual central axis 15 is measured relative to the ideal central axis 14 and correction signals are generated from the deviation. With the linear actuators 13, of which FIG. 3 shows only the upper linear actuator and/or its armature 13, the strip is moved into the desired position, i.e. into the ideal central position. To this end, the linear actuators 13, whose horizontal force component acts (essentially) perpendicular to the strip-travel direction and opposite the direction of deflection of the strip, act on the metal strip 1 that, as the armature, is also part of the linear actuator 13. FIG. 3 also shows that the linear actuators 13 extend over the total width of the strip and consequently cover the entire width of the strip. The sensor 12 shown here is a noncontact sensor and/or operates with noncontact functioning sensors, for example inductive sensors, capacitive sensors, optical sensors or also with a radar measurement.

(10) The figures show only a strip-position adjuster 7. However, strip-position adjusters 7 are especially preferably also provided in the cooling zone 4 and between the heating zone 3 and the cooling zone 4, not just in the heating zone 3. With a suitable length of the heating subzone, a plurality of strip-position adjusters 7 may be integrated into the heating zone 3 so that a strip-position adjuster 7 may for example be provided at least once every 50 m, preferably at least once every 30 m, in the heating zone 3. It is possible in this way to work with furnaces of almost any desired length so that the capacity of the installation is increased.

(11) Furthermore, it is self-evident that the strip-position adjuster integrated into the furnace (in other words, the linear actuator and the strip-position detector) is connected to a suitable electronic controller that of course need not be located inside the furnace and are not necessarily the subject matter of the strip-position adjuster according to the invention.