METHOD AND DEVICE FOR COATING A METAL STRIP WITH A COATING MATERIAL WHICH IS AT FIRST STILL LIQUID

Abstract

A method and a device for coating a metal strip with a coating material which is at first still liquid. A first displacing device for displacing an electromagnetic stabilisation device relative to a blowing device in the plane transverse to the direction of transport of the metal strip is provided.

Claims

1-14. (canceled)

15. A method of coating a metal strip with an initially still liquid coating material, comprising: passing the metal strip to be coated through a coating container filled with the liquid coating material; blowing excess parts of the still liquid coating material off the surface of the metal strip with the help of a blowing device after passage through the coating container; stabilising the metal strip, after leaving the blowing device, with the help of an electromagnetic stabilising device which is arranged downstream of the blowing device in the transport direction of the metal strip and which is supported on the blowing device; displacing the electromagnetic stabilising device relative to the blowing device in a plane transverse to the transport direction of the metal strip so that the actual position of the metal strip at least approximately corresponds with a predetermined target centre position in the slot of the electromagnetic stabilising device; and regulating the actual position of the metal strip to the predetermined target centre position by suitable displacement of the blowing device in a plane transverse to the transport direction of the metal strip; wherein deviation of the actual position of the metal strip from a predetermined target centre position in the slot of the blowing device is detected; the displacement of the blowing device is directly or indirectly detected relative to a pass line reference position; and the displacement of the electromagnetic stabilising device is carried out as a function of and in opposite direction to the detected displacement of the blowing device so that as a result the electromagnetic stabilising device remains at its original location.

16. The method according to claim 15, wherein the detected deviation of the actual position of the metal strip in the slot of the electromagnetic stabilising device or the blowing device is a translational shifting parallel to a longitudinal direction defined by the target centre position and a rotation relative to the predetermined target centre position of the metal strip in the slot of the electromagnetic stabilising device or the blowing device.

17. The method according to claim 15, wherein the detected deviation of the actual position of the metal strip is a translational shifting in width direction (x) relative to the predetermined target centre position of the metal strip in the slot of the electromagnetic stabilising device or the blowing device.

18. A device for coating a metal strip with a liquid coating material, comprising: a coating container, which is fillable with the liquid coating material, for conducting through the metal strip to be coated; a blowing device, which is arranged above the coating container, for blowing excess parts of the still liquid coating material off the surface of the metal strip after conducting the metal strip through the coating container; an electromagnetic stabilising device, which is arranged above the blowing device and supported by the blowing device, for stabilising the metal strip after leaving the coating container and the blowing device; a first displacing device for displacing the electromagnetic stabilising device relative to the blowing device in the plane transverse to the transport direction (R) of the metal strip; a control device for controlling the first displacing device; a second displacing device for displacing the blowing device; and a regulating device for regulating the actual position of the metal strip to a predetermined target centre position of the metal strip in a slot of the blowing device by displacement of the blowing device with the help of the second displacing device in a plane transverse to the transport direction (R) of the metal strip; wherein a first detecting device is provided for detecting deviation of the actual positon of the metal strip from a predetermined target centre position in the slot of the blowing device; the second displacing device is constructed for displacing the blowing device as a function of the detected deviation of the actual position of the metal strip from a predetermined target centre position in the slot of the blowing device; a second detecting device is provided for detecting the displacement of the blowing device relative to a pass line reference position; and the control device is constructed for displacing the electromagnetic stabilising device as a function of and in opposite direction to the displacement, which is detected by the second detecting device, of the blowing device so that as a result the electromagnetic stabilising device remains at its original location.

19. The device according to claim 18, wherein the first displacing device for displacing the electromagnetic stabilising device is arranged between the blowing device and the electromagnetic stabilising device.

20. The device according to claim 18, further comprising: a human machine interface (HMI) for an operator of the device for visualisation of the detected deviation of the actual position of the metal strip from the target centre position in the slot of the blowing device or the electromagnetic stabilising device or the detected deviation of the blowing device from the pass line reference position or for visualisation of the change in the deviations over time.

Description

[0016] Accompanying the invention are three figures, in which:

[0017] FIG. 1 shows the device according to the invention; and

[0018] FIGS. 2 and 3 show plan views of the slot of the blowing device according to the invention or the electromagnetic stabilising device according to the invention each with marking of the target centre position and different desired actual positions of the metal strip.

[0019] The invention is described in detail in the following in the form of embodiments with reference to the mentioned figures. The same technical elements are denoted by the same reference numerals in all figures.

[0020] FIG. 1 shows the device 100 according to the invention for coating a metal strip 200 with a liquid coating material 300, for example zinc. For this purpose, the initially still uncoated metal strip 200 is conducted in transport direction R in a coating container 110 filled with the liquid coating material. Within the coating container 110 the metal strip 200 is deflected with the help of a deflecting roller so that it leaves the coating container at the top. After the transit through the coating container, the still liquid coating material adheres to the metal strip 200.

[0021] Arranged above the coating container 110 is a blowing device 120 which spans a slot 122 through which the metal strip 200 is guided. Excess coating material is blown off the surface of the metal strip 200 with the help of the blowing device.

[0022] In order that blowing onto the upper side and lower side of the metal strip 200 takes place uniformly it is important that the metal strip 200 runs through the slot 122 of the blowing device 120 in a predetermined target centre position 128, as symbolised in FIG. 2 in the form of the solid line in X direction. This target centre position is distinguished by, in particular, uniform spacings or spacing distributions from the inner edges of the slot 122 of the blowing device 120. Possible undesired actual positions of the metal strip are also drawn, as dashed lines, in FIG. 2 near the desired predetermined target centre position. Undesired actual positions for the metal strip are thus present, for example, if it is twisted relative to the target centre position or shifted parallelly in Y direction.

[0023] FIG. 3 shows a third possible undesired actual position, in which the metal strip 200 is parallelly shifted in X direction, i.e. in width direction, relative to the target centre position.

[0024] With further reference to FIG. 1 there can be seen above the blowing device 120 an electromagnetic stabilising device 140 which in turn has a slot 142 through which the metal strip 200 is similarly guided. It is also the case here that the metal strip 200 runs through the slot 142 preferably in a predetermined target centre position 128, as shown in FIGS. 2 and 3, so that the forces provided by the electromagnetic stabilising device 140 can have a stabilising action in desired manner uniformly on the metal strip 200. The same applies to the slot 142 and the centre position, which is also desired thereat, as beforehand with reference to FIGS. 2 and 3 for the slot 122 of the blowing device 120.

[0025] The electromagnetic stabilising device 140 is mechanically supported on the blowing device 120. However, according to the invention this support is not carried out rigidly, but by way of a first displacing device 160 provided between the blowing device 120 and the electromagnetic stabilising device 140. In concrete terms, the first displacing device 160 enables displacement of the electromagnetic stabilising device 140 relative to the blowing device in a plane transverse to the transport direction R of the metal strip. The displacing device 160 is controlled with the help of a control device 170.

[0026] In addition, a first detecting device 154 for detecting a deviation of the actual position of the metal strip 200 from a predetermined target centre position in the slot 122 of the blowing device 120 is arranged between the stabilising device 140 and the blowing device 120. Alternatively, the first detecting device 154 can also be constructed only for detection of the actual position of the metal strip. Moreover, a regulating device 180 is provided for regulating the actual position of the metal strip 200 to a predetermined target centre position in the slot 122 of the blowing device, as explained above with reference to FIGS. 2 and 3, through displacement of the blowing device 120 with the help of a second blowing device 130. The regulation is carried out in response to the detected deviation. If determination of the deviation of the actual position from the target centre position does not take place in the first detecting device 154, it can also be undertaken, for example, within the regulating device 180. The displacement is carried out in a plane transverse to the transport direction R of the metal strip as a function of the detected deviation of the actual position of the metal strip from the predetermined target centre position in the slot 122 of the blowing device. In other words, if it is ascertained that the metal strip 200 does not run through the slot 122 in the target centre position 128, then the blowing device 120 is so displaced with the help of the second displacing device 130 that the metal strip again runs through the slot 122 of the blowing device in the predetermined target centre position 128. For that purpose, the first detecting device 154 is constructed so that it can preferably detect all three actual positions of the metal strip 200 deviating from the target centre position 128 as described above with reference to FIGS. 2 and 3.

[0027] The said displacement of the blowing device 120 does not have to have an effect on the electromagnetic stabilising device 140, which is supported on the blowing device 120. For that purpose, the control device 170 is constructed to control the first displacing device 160 in such a way that the electromagnetic stabilising device 140 in the case of a displacement of the blowing device 120 relative to a pass line reference position is not moved therewith, but can remain at its original location. The control device 170 accordingly acts in such a way on the first displacing device 160 that in the case of a displacement of the blowing device 120 the electrical stabilising device 140 preferably makes precisely the opposite movement to the blowing device 120, i.e. as a result preferably remains at its original location.

[0028] In order to realise this special form of control for the first displacing device 160 the control device 170 can evaluate different situations. On the one hand, the control device 170 can be constructed to perform displacement of the electromagnetic stabilising device 140 as a function of the deviation, which is detected by the first detecting device 154, of the actual position of the metal strip from the predetermined target centre position of the metal strip in the slot 122 of the blowing device 120.

[0029] Alternatively or additionally, the control device 170 can be constructed to perform the displacement of the electromagnetic stabilising device as a function of and in opposite direction to the displacement, which is detected by a second detecting device 155, of the blowing device 120.

[0030] Finally, according to a further alternative or additionally the control device 170 can be constructed to cause displacement of the electromagnetic stabilising device 140 as a function of a detected deviation of the actual position of the metal strip from a predetermined target centre position in the slot 142 of the electromagnetic stabilising device. A precondition for that is that a third detecting device 145 is present for detecting the said deviation of the actual position of the metal strip from the predetermined target centre position in the slot 142 of the electromagnetic stabilising device 140.

[0031] The first, second and third detecting devices 154, 155, 145 are constructed to preferably recognise all conceivable deviations of an actual position of the metal strip from the desired target centre position. Amongst those is, in particular, a (parallel) shifting of the metal strip in X or Y direction or a rotation such as explained above with reference to FIGS. 2 and 3. Accordingly, the first and second displacing devices 130, 160—in the case of suitable control by the regulating device 180 or the control device 170—are constructed to move the blowing device 120 and the electromagnetic stabilising device 140 in a desired manner in a plane transverse to the transport direction R of the metal strip, particularly to shift (parallelly) or to rotate so as to realise running-through of the metal strip in the target centre position. To that extent, the illustration of the first and second displacing devices 160, 130 as a carriage or piston-cylinder unit is in each instance merely exemplifying, but not limiting.

[0032] The first and third detecting devices 154, 145 as well as optionally also the second detecting device 155 can be realised in the form of a single sensor device 150, which, for example, is constructed in confocal manner or is laser assisted. To that extent, the sensor device—also termed ‘laser’ for short—forms a constructional unit for the mentioned detecting devices. The sensor device 150 can also be generally termed spacing detection device.

REFERENCE NUMERAL LIST

[0033] 100 device

[0034] 110 coating container

[0035] 120 blowing device

[0036] 122 slot of the blowing device

[0037] 128 target centre position of the metal strip in the blowing device or the electromagnetic stabilising device

[0038] 130 second displacing device

[0039] 140 electromagnetic stabilising device

[0040] 142 slot of the electromagnetic stabilising device

[0041] 145 third detecting device

[0042] 150 sensor device

[0043] 154 first detecting device

[0044] 155 second detecting device

[0045] 160 first displacing device

[0046] 170 control device

[0047] 180 regulating device

[0048] 200 metal strip

[0049] 300 coating material

[0050] R transport direction of the metal strip

[0051] X width direction of the metal strip in target centre position

[0052] Y direction transverse to the plane spanned by the metal strip