EP4326918A1

EP4326918A1 - Coating plant for coating a strip and method for coating a strip

Info

Publication number: EP4326918A1
Application number: EP22710291.0A
Authority: EP
Inventors: Janine-Christina SCHAUER-PASS; Michael Strack
Original assignee: ThyssenKrupp Steel Europe AG
Current assignee: ThyssenKrupp Steel Europe AG
Priority date: 2021-04-23
Filing date: 2022-01-27
Publication date: 2024-02-28
Also published as: WO2022223156A1; US20240158908A1; DE102021110394A1; JP2024517433A; CN117203366A

Abstract

The invention relates to a coating plant for coating a strip (2), for example a steel strip, with a material present in the gas phase. The coating plant comprises: - a coating chamber, - a device for vapour deposition of the material, - a strip positioning assembly for correcting the strip transport. The strip positioning assembly has a first guide roller (12) and a second guide roller (13). In particular, pivoting about the pivot point (22) is possible, and can be effected by the adjusting unit (23). The invention also relates to a method for coating a strip (2).

Description

Coating system for coating a strip and method for coating a strip

The invention relates to a coating system for coating a strip. The invention also relates to a method of coating a strip.

For the coating of strip, in particular metallic strip, such as steel strip, methods can be used which are based on the principle of so-called gas phase deposition. The principle of vapor deposition is to provide a starting material and bring it into the vapor phase. The components of the material present in the gas phase, in particular atoms and/or ions, move in a coating chamber and are directed towards an area in which the coating is to take place, which is referred to below as the coating zone. The strip is transported through the coating zone so that the components of the material present in the gas phase settle on the strip to be coated and thereby form a coating.

An advantage of gas phase deposition is that coatings can be produced with good economic efficiency, the properties of which can be influenced to a large extent and in a wide range of properties. Another advantage is that vapor deposition can be used to produce coatings on many different materials. In contrast to some other processes, gas phase deposition is suitable, for example, for the production of coatings with a high-melting point Material or coatings with metastable phase or metastable phase material.

The present invention relates to an apparatus for vapor deposition of material, wherein the vaporized material is directed out to the coating zone through a nozzle exit of a nozzle portion of the apparatus for vapor deposition of material.

The strip is guided past a device for gas phase deposition within a coating chamber and is coated with components present in the gas phase emerging from this device. It is desirable here for the coating to be applied as homogeneously as possible not only in the longitudinal direction of the strip but also in the transverse direction of the strip, that is to say in particular: with a homogeneous thickness. Against the background that both the tape transport itself is subject to fluctuations and, depending on the specific circumstances of the coating (material, geometry of the nozzle, etc.), a homogeneity of the movement of the materials present in the gas phase can vary, the present invention is based on the object of a achieve improved homogeneity of the coating.

The object is achieved with a coating system having the features of claim 1 and with a method for coating a strip having the features of claim 13.

The coating system is intended to be able to coat a strip and has the following components for this purpose:

The coating system has a coating chamber. The coating chamber has a chamber inlet and a chamber outlet, with the strip to be coated being fed into the chamber inlet, through the chamber and out again from the chamber outlet. The coating chamber is typically a largely closed chamber in which a technical vacuum is preferably provided can, for example between 10 ^{( 3)} mbar and 100 mbar, preferably with less than 20 mbar.

The coating chamber also has a device for gas phase deposition of the material. The device for gas phase deposition comprises an evaporation section, in which the material originally provided as starting material is evaporated into the gas phase, and a nozzle section, with which the material then present in the gas phase is directed in the direction of the strip surface to be coated, so that the material from a nozzle outlet of the Nozzle section flowing gas phase particles flow towards the coating zone.

Evaporation of the starting material can be accomplished in any known manner, such as thermal evaporation, arc evaporation, and others and combinations of the foregoing. It is essential within the scope of the present invention that after passing through the evaporation section the material is in the gas phase and is then guided by means of the nozzle section towards the strip surface to be coated and condenses on it when it reaches the strip surface.

The web passes through the coating zone, which is an area where the gas phase material impacts the web as it is continuously transported through the coating chamber. Thus, the web is continuously exposed to the gas phase material such that the continuous movement of the web as it is transported through the chamber forms the desired coating as a result of condensation of the gas phase material on the web surface.

Optionally, a coating channel can be arranged within the coating chamber, which is equipped with heating means for Heating is equipped and through which the strip is transported through at least in the area of the coating zone.

The terms gas phase and evaporation are used throughout the description as they are commonly used in the field of technologies using vapor phase deposition. The term gas phase includes that a small proportion by weight, for example up to 30 percent by weight, preferably no more than 10 percent by weight, of the material present in the gas phase is not in the gas phase in the strictly physical sense, but instead is present as a vapor, as an aerosol and/or present as a cluster. The term vaporization means that, depending on the material used and the technology used, the transition of the particles into the gas phase takes place at least in part with mechanisms other than vaporization in a strictly physical sense, for example by sublimation. In the context of the use of language in the field of gas phase deposition and thus in the context of the present description, the term vaporization therefore also includes vaporization in the strictly physical sense, ie a transition to liquid Gas phase, also other mechanisms, such as sublimation in particular. Likewise, the material present in the gas phase is also referred to as material vapor.

A tape positioning arrangement is arranged in front of the coating zone, viewed in the direction of tape transport. The tape positioning arrangement serves the purpose of contributing to a continuous correction of the tape transport. For this purpose, the belt positioning arrangement has at least one first guide roller arranged on the first side of the belt and a second guide roller arranged on the second side of the belt. The first guide roller and the second guide roller are positioned such that when the belt is transported, both the first guide roller and the second guide roller, namely the first, are in contact with the belt guide roller with the first belt surface and the second guide roller with the second belt surface.

A strip positioning arrangement comprising two guide rollers positioned in front of the coating zone and both in contact with the strip surface, preferably continuously, causes the strip tracking of the strip to be corrected immediately before the strip surface is coated with the material vapor. After passing through the positioning arrangement, the strip is closer to a model ideal strip run than before. In particular, the transverse bow of the belt is closer to a desired state, preferably the transverse bow is reduced and most preferably eliminated. The term transverse curvature is known in the technical field of tape transport: It describes a deviation of the tape from the ideal tape plane in the form of a bulge in the cross-section of the tape in a direction perpendicular to the transport direction. Thus, when the surfaces of the strip form curved curves rather than straight lines in cross-section, transverse bowing is present. The aim is to keep the transverse curvature low or to eliminate it completely, which is achieved with the coating system according to the invention and its developments. The procedure according to the invention advantageously means that the strip in the coating zone is subject to fewer fluctuations in transverse curvature throughout the entire coating period, with the result that coating is more homogeneous not only in the longitudinal direction of the strip but also in the transverse direction of the strip compared to coating carried out without a positioning arrangement.

This means that the correction of the tape transport includes at least the correction of the lateral bow, that is: the reduction or the elimination of the lateral bow. The correction of the transverse curvature is provided by the ones placed on both sides of the belt and in contact with the belt Guide rollers, ie the first guide roller and the second guide roller, reached.

It is preferred that the axis of rotation of one of the two guide rollers is fixed or is set up for continuous fixing during the transport of the tape, and the axis of rotation of the other of the two guide rollers at the point of contact of the roller shell with the tape can be moved in a direction perpendicular to the tape surface or in a direction with a to the tape surface perpendicular directional component is movable. This means that the position of the guide roller can be changed in the direction perpendicular to the belt surface, so that the still rotatable guide roller influences the guidance of the belt in different ways depending on the selected position of the axis of rotation, for example by shifting the pivot in the direction pointing to the belt pronounced as Bringing about a slight deflection. The deflection is achieved in that, from a top view of the tape positioning arrangement in the direction of tape transport, the lower edge of the first guide roller is below the upper edge of the second guide roller when the first guide roller is viewed as the upper guide roller, regardless of its actual spatial positioning. This movement of the axis of rotation in a direction perpendicular to the surface of the strip can be achieved, for example, by an adjustment unit designed to suit the vacuum, which is arranged inside the coating chamber. Alternatively, a mechanism present outside of the coating chamber can also be arranged on the coating system for movement perpendicular to the strip surface, with an entry point of a device causing the movement, for example a metal rod, for example as a passage into the Vacuum chamber is formed, wherein the implementation is preferably realized with a vacuum-tight bellows.

For example, it can be provided that the guide roller present on the side of the nozzle outlet is fixed and the roller of the strip opposite the nozzle outlet is designed as a roller that can be moved perpendicularly to the strip surface. It is particularly advantageous if there is an embodiment in which the movement relative to the belt surface has such a degree of freedom that a movement of the guide roller, which can be moved perpendicularly to the belt surface, exerts a pressure pointing perpendicularly to the surface on the surface of the belt in cooperation with a pressure brought about by the stationary roller back pressure. With such an arrangement it can be achieved that by exerting pressure by increasing a deflection of the movable roller in the direction of the belt surface, an increasing force is exerted on the surface along a contact line on the casing of the guide roller along the axis of rotation of the guide roller on the belt. The consequence of this is that the belt adapts in its transverse direction to the profile of the movably arranged roller. For example, in a preferred case in which the roll has a circular-cylindrical arc, any transverse arc that may be present, ie a deviation of the transverse profile of the strip from a straight line, can be compensated for or at least partially compensated. Since the guide roller, which can be moved perpendicularly to the strip surface, rotates with the strip movement, this corrective effect can be carried out during the entire coating process and - if desired - along the entire strip length, so that after the coating process there is a strip whose coating has excellent homogeneity in every direction lying on the tape surface.

The fact that a relative movement of the movably trained guide roller compared to the fixed trained guide roller is possible, it is made possible that a force acting perpendicularly on the belt surface can be achieved with comparatively inexpensive means, namely by providing only one movable roller.

A minimal use of force of the movable roller is given, for example, in a preferred basic position, in which the outer casing of the movable guide roller and the outer casing of the fixed guide roller have tangential planes pointing parallel to one another and parallel to the belt surfaces, the distance between which corresponds to the thickness of the belt. According to this development, the mobility of the other of the two guide rollers is preferably implemented in such a way that the movable roller is mounted so that it can move from the basic position described in the direction of the half-space in which the non-movable roller is located; or in other words: the axis of rotation of the movable roller can be moved in a direction perpendicular to the belt surface in such a way that the belt is forced into a deflection course. This is accomplished in that, geometrically speaking, the plane parallel to the belt surface of the undeformed belt, which contains the axis of rotation of the movable guide roller, is moved in the direction of the plane parallel to the undeformed belt surface, which contains the axis of rotation of the fixed axis of rotation, such that the distance between these two levels becomes smaller than the sum of the two radii of the two guide rollers plus the strip thickness. With increasing movement of the axis of rotation of the movable guide roller in the direction described, this distance decreases, which is accompanied by an increase in the force acting on the belt surface, which in turn achieves an increasing elimination of any transverse arches that may be present. This mechanism is a preferred variant of the strip positioning arrangement, with which elimination or reduction of transverse bows in the strip to be coated can be achieved in a comparatively inexpensive manner. It is particularly preferred if the first guide roller and the second guide roller are spaced apart from one another on the coating system when viewed in the direction of strip transport, i.e. the two contact lines formed by the guide rollers with the strip are spaced apart from one another as seen in the direction of strip transport. As a result, the guidance of the strip can be influenced in a particularly advantageous manner in such a way that a transverse bend in the strip is eliminated or at least reduced, so that ultimately there is neither a concave transverse bend nor a convex transverse bend, viewed from the nozzle outlet, or the respective transverse bend at least can be reduced from its extent in front of the positioning arrangement.

It is preferred if the belt positioning arrangement is arranged immediately before the coating zone. This preferably means that the coating zone begins a maximum of 11 meters, particularly preferably a maximum of 4 meters, after the belt positioning arrangement. The positioning of the band positioning arrangement directly in front of the coating zone ensures that a band positioning brought about for the purpose of coating is still completely or at least almost completely retained by reducing or eliminating transverse arches at the location of the coating.

According to an advantageous further development, it is provided that a layer thickness sensor is arranged behind the coating zone, seen in the direction of belt transport, which is suitable for a non-contact determination of layer thickness values of the previously applied coating. For this purpose, the sensor is aimed at the coating, preferably in a perpendicular viewing direction, in order to measure and record the layer thickness or a value dependent on the layer thickness. The tape runs past the layer thickness sensor during tape transport, so that sequentially or continuously Layer thickness values, in particular layer thicknesses, can be determined along the length of the strip. The measured values can then be used to make changes in the layer thickness for a one-time, repeated or continuous adjustment, preferably a regulation, of the belt positioning. For example, if a measured thickness deviates from a target thickness or if there is a relative change in the layer thickness beyond a certain level, the strip positioning can be regulated or regulated. Alternatively or additionally, the coating can also be adjusted by changing a control of the device for gas phase deposition, which for this purpose is preferably coupled to the layer thickness sensor via a corresponding coating control. It is particularly preferred if the layer thickness sensor is in the form of an X-ray fluorescence sensor, since such a sensor can be obtained inexpensively and operated with little effort and maintenance effort, while ensuring a sufficiently high detection accuracy.

In a further development, the layer thickness sensor is positioned so that it can traverse, for example arranged on the coating chamber, and can be moved by means of a layer thickness sensor adjustment mechanism. The layer thickness sensor adjustment mechanism can, for example, be constructed to suit the vacuum and arranged inside the coating chamber. The layer thickness sensor adjustment mechanism can be designed, for example, electrically or pneumatically. Alternatively, the layer thickness sensor adjustment mechanism can be arranged outside of the coating chamber and coupled into the coating chamber via a passage, for example by means of bellows. The layer thickness sensor adjustment mechanism is preferably provided with a motor for the adjusted and/or regulated control of the position of the layer thickness sensor in the transverse direction of the strip. the The aforementioned traversingly movable arrangement of the layer thickness sensor on the coating system serves the purpose of detecting layer thickness values, which contain information about the layer thickness profile of the coated strip in the transverse direction of the strip. This means that deviations from the

Layer thickness profile can be recognized from a desired or an expected layer thickness profile and these can be used to draw conclusions about any unplanned properties of the strip positioning, in particular, for example, the formation of a transverse bow in the strip and/or an inhomogeneity in the exposure of the strip to the material vapor from the device for vapor deposition of the material as a result possible inhomogeneities in the material vapor emerging from the nozzle outlet.

Alternatively or additionally, a further developed embodiment of the coating system can have a distance sensor. Such a sensor can then be used to detect a change in the distance from the sensor and thus any change in the running of the strip that may occur, for example caused by fluctuations in the strip tension. Knowing the measured values obtained from the distance sensor, the homogeneity of the coating applied can then be improved by adjusting the coating system, in particular by readjusting the belt positioning using the belt positioning arrangement. For example, an inductive distance sensor or a capacitive distance sensor, as are familiar to the person skilled in the art, can serve as the distance sensor.

If a distance sensor is present, it is positioned in such a way that the distance of a region of the tape running behind the tape positioning arrangement, viewed in the direction of tape transport, is detected. The distance sensor is preferably positioned in front of the coating zone, so that a distance of one in front of the coating zone, viewed in the tape transport direction current area of the tape is detected. This has the advantage that the distance is measured in an area that is comparatively close to the belt positioning arrangement, as a result of which the prerequisites for a particularly precise setting or regulation of the belt positioning arrangement as a function of the distance are brought about.

If a layer thickness sensor is present, it is positioned in such a way that the layer thickness of a coating of a region of the strip running behind the coating zone, viewed in the direction of strip transport, is detected.

In a preferred development, it is provided that the distance sensor is movably positioned in a traversing manner, for example arranged on the coating chamber, and is designed to be movable on the coating system by means of a distance sensor adjustment mechanism. Analogously to the above explanations in connection with the traversing movement of the layer thickness sensor, the distance sensor can then track distance information not only at a fixed position in the transverse direction of the strip and for changing longitudinal positions, but distance information can also be provided along at least a section of the transverse direction of the strip, preferably the entire transverse direction of the strip, are detected and thus transverse direction position-dependent distance profiles or changes in distance profiles are detected. This embodiment has the advantage that, based on the information obtained in this way, the strip positioning can be corrected in a particularly advantageous manner and the homogeneity of the coating can thereby be improved.

According to a development, the layer thickness sensor, if present, and/or the distance sensor, if present, is coupled to the belt positioning arrangement via a control device. The control unit is set up to read out values of the respective sensor or sensors, that is: to read out layer thickness values and/or distance values, and the Controlling a belt positioning arrangement in order to set, preferably regulate, a belt positioning as a function of detected layer thickness values and/or distance values. This means that the coating system has a control unit which receives data from the layer thickness sensor and/or the distance sensor (depending on which of these sensors is present or which of these sensors are present) and is able to use these transmitted values to position the strip positioning system to control to adjust the tape positioning. The belt positioning can be adjusted in particular by moving the guide roller, which can be moved in a direction perpendicular to the belt surface. For example, provision can be made to move the guide roller, which can be moved in the direction perpendicular to the belt surface, towards the belt in order to bring about an increasing force and, with increasing movement towards the belt, also a corresponding deflection of the belt, and consequently to bring about a reduction in any transverse bow that may be present . The corresponding device of the control device can be implemented, for example, in such a way that empirically obtained data sets are stored on the control device, which link a dependency between the position of the guide roller, which can be moved in the direction perpendicular to the belt surface, on the one hand, and a change in the transverse arc with a change in the position of this guide roller, on the other hand. Alternatively, however, it can also simply be provided that the control unit is enabled to implement a control loop using corresponding program sequences, which works with layer thickness and/or distance as the controlled variable and, after detection of a deviation of the controlled variable from the corresponding setpoint value, a change in the position of the in the vertical direction brings about the tape surface movable guide roller and based on the then again detected controlled variable determines whether thereafter a further change in the position of the perpendicular to the Band surface movable guide roller is required and how this is carried out. In other words, a further development is provided as a coating system in which the change in the position of the movable roller

Belt positioning arrangement the manipulated variable is for controlling the controlled variable selected as layer thickness and/or distance.

In order to be able to bring about an adjustment of the transverse arc, preferably a regulation of the transverse arc, the coating system preferably has the above-mentioned traversingly movable layer thickness sensor in order to carry out the control, preferably regulation, based on determined layer thickness profiles. As an alternative to a traversingly movable layer thickness sensor, there can also be a number of two or more layer thickness sensors, preferably at least three layer thickness sensors, which are arranged at a suitable longitudinal position of the strip behind the coating zone in such a way that they point to different, for example equidistant, positions in the transverse direction of the band. What is achieved with this embodiment is that a layer thickness profile is obtained without the need for a traversing layer thickness sensor.

Alternatively or additionally, it can be provided that the axis of rotation of the first guide roller and the axis of rotation of the second guide roller are coupled to one another in a rotationally fixed manner via a mechanical connection, i.e. both have a constant angle to one another and are preferably oriented parallel to one another, but the mechanical connection itself is pivotably mounted is, wherein the pivoting preferably takes place in a parallel to the tape transport direction pivot axis. The tape positioning arrangement, thus the first guide roller and the second guide roller, can thus be pivoted together about the pivot axis in such an embodiment, with the orientation relative to one another being unchanged with regard to their angle to one another. The pivoting takes place, for example by means of a pivoting device coupled to the belt positioning arrangement, which can be designed, for example, as an entirety of adjustment unit and coupling element, for example connecting rod, between adjustment unit and belt positioning arrangement. The adjustment unit acts, for example, on the mechanical connection with which the first guide roller and the second guide roller are connected to one another, at a position on that side of the belt which is further away from the pivot axis, so that by adjusting the - for example designed as a lifting rod - Adjusting the pivoting of the first guide roller and the second guide roller takes place. The adjusting unit for the rotary movement can, for example, be designed to be vacuum-compatible and arranged inside the coating chamber, but alternatively an arrangement provided outside the sealing chamber is also possible. The adjusting unit is preferably designed pneumatically or electrically as an electric motor. A pivotable arrangement of the strip positioning arrangement with a joint pivoting of the rotational axes oriented in a torsion-resistant manner relative to one another achieves the advantage that any deviations in the strip position from the ideal center strip position can be corrected. This brings about immediate improvements in layer homogeneity, in particular in the layer thickness distribution.

In the context of the present description, the band position refers to the casing section of the guide roller viewed in the direction of the axis of rotation, on which the band is conveyed. With pivoting of the tape positioning assembly, the tape location is corrected to a desired portion. It is preferably desired that the belt is guided either centered on the casing section of at least one, preferably all, non-pivotable rollers of the belt run; in such a case, within the scope of the present description, the preferably desired case of the middle position of the strip is spoken of. Particularly preferred is an embodiment in which both the axis of rotation of at least one of the two guide rollers at the point of contact of the belt with the guide roller can be moved in a direction perpendicular to the belt surface or in a direction with a directional component perpendicular to the belt surface to the other guide roller and the belt positioning arrangement is pivotably mounted is. Such a constellation leads to the further advantage that the same device can be used to avoid or largely avoid the transverse curvature and also to largely or completely maintain the strip center position.

The coating system particularly preferably has an optical strip position sensor, which is arranged behind the strip positioning arrangement in the direction of strip transport and is coupled to the pivoting device via a control device, if it can be swiveled with the coating chamber and has axes of rotation of the guide rollers that are coupled in a rotationally fixed manner to one another. The control device is prepared to control the pivoting device for setting, preferably for regulating, the tape position by pivoting the tape positioning arrangement as a function of a sensor signal from the tape position sensor. This can be implemented, for example, by empirically found data being stored in a memory area of the control device, which assigns a pivoting movement to be carried out to a sensor-detected deviation of a strip position from the strip center position and also carries out this by controlling, for example, a corresponding existing motor such as an electric motor. The control device for setting, preferably for regulating, the pivoting of the strip positioning arrangement for bringing about or bringing the strip position closer to the strip center position can be implemented as a separate second control device independently of the control device already mentioned for controlling the relative position of the guide rollers to one another, but the control device can also be a separate memory area of this control unit already mentioned.

The device for vapor deposition of the material is preferably a jet vapor deposition device.

The term jet vapor deposition device is understood by the person skilled in the art to mean a device in which the coating material is brought into the gas phase thermally, for example in a crucible, and then - typically in a gas stream together with a carrier gas stream of inert gas, in some forms but also as a gas flow exclusively from the material brought into the gas phase - is transported to the substrate, preferably at a gas flow rate above the speed of sound, particularly preferably above 500 m/s. The way it works is explained, for example, in the review article in the Handbook of Deposition Technologies for Films and Coatings (Third Edition), Science, Applications and Technology, 2010, pages 881-901, https://doi.org/10.1016/B978-0-8155- 2031-3.00018-1 (linked on the filing date).

The surface to be coated is usually located in an atmosphere which has a negative pressure compared to the atmosphere prevailing in the crucible. The surface to be coated is, for example, in a technical vacuum with a pressure of preferably less than 100 mbar, for example between 10 ⁽³⁾ mbar and 20 mbar, which in large-scale implementation is a good compromise between good properties of the coating and the effort required for the creation and maintenance of the vacuum is to be operated.

The advantages of the JVD process are particularly evident in the large-area coating of strip, especially of metallic strip such as steel strip. An advantage of JVD is that due to the comparatively high pressure with which the material present in the gas phase is directed to the surface to be vaporized, the strip can be coated at a high coating rate For example, with a correspondingly high selected strip speed, it brings the advantage of strip coating with good economics.

In an alternative preferred development, the device for gas phase deposition of the material is designed with an evaporation section, which has a pre-evaporation section and a post-evaporation section, preferably designed as a crucible, with the pre-evaporation section having a spray head for preparing the coating material present as the starting material and an injector tube. The injector tube is designed to conduct the coating material processed in the spray head to the post-evaporation section and to bring the processed coating material into the post-evaporation section in order to convert it there into the gas phase.

Preferably, the spray head is a wire gun for arc melting and/or arc evaporation of starting material introduced into the wire gun. The material used to form the respective coating is, for example, in the form of a wire or strip. The starting material is brought into the area of influence of an electric arc, with preferably two wires or two strips of the starting material being present, one of which is connected as a cathode and one as an anode with an electrical DC voltage source and a voltage sufficient to form an arc is set with the DC voltage source . The material melted and/or vaporized by means of the energy of the arc flows by means of a gas flow from a gas or a gas mixture into the interior of a to a temperature that corresponds at least to the vaporization temperature of the at least one material used for the coating or of the material with the respective highest vaporization temperature , heated chamber, the so-called crucible, through an inlet. In the process, the vaporizes Material(s) in the crucible completely and exit(s) through an opening provided on the crucible. The vaporized material(s) strikes the surface to be coated of the component of the strip-shaped material or workpiece to form the respective coating.

A nozzle section which is coupled to the post-evaporation section and has the nozzle outlet and ends therewith preferably follows.

In a special case that correspondingly high exit velocities of the material emerging from the post-evaporation section are achieved, this alternative embodiment can be regarded as a variant of the JVD.

One idea of the invention relates to a method for coating a strip using a coating system. The method can be carried out, for example, with a coating system of the type mentioned at the beginning or one of its developments. The method has at least the following steps:

A strip is transported through a coating zone of the coating plant, in which a strip surface of the strip is then coated.

During the coating, one of the following parameters is determined repeatedly or continuously: a) Layer thickness value by means of a layer thickness sensor, the layer thickness value being able to be a layer thickness or a layer thickness profile, for example. b) distance value by means of a distance sensor, wherein the distance value can be a distance or a distance profile, for example.

The parameter is continuously compared with a setpoint. The target value can be, for example, a comparison value or a comparison curve or a parameter set of curves. If the at least one parameter deviates from the target value by more than one tolerated deviation, the belt positioning arrangement is activated to adjust the transverse arc of the belt, the belt positioning arrangement having at least one first guide roller arranged on the first side of the belt and a second guide roller arranged on the second side of the belt and wherein the first guide roller and the second guide roller are positioned in such a way that when the belt is transported, both the first guide roller and the second guide roller are in contact with the belt and one of the two guide rollers is at the point of contact of the belt with the guide roller towards the belt surface is movable in a vertical direction, optional: repeating the previous two steps until the target value is reached in a controlled manner or a value that deviates from the target value by less than a tolerated deviation, but at most the tolerated deviation, for the controlled setting of the transverse arch de s bands.

The control or regulation of the transverse arc by changing the position of the first, movable, guide roller unfolds its advantages in a special way when the

Layer thickness determination is used as a controlled variable, which is why a coating system with a layer thickness sensor and a method for coating with the layer thickness as a controlled variable represent particularly preferred embodiments of the present developments.

In a preferred development of the method, a strip position of the strip is also determined using an existing strip position sensor, and if the strip position deviates from a setpoint value, preferably the strip center position, by more than a tolerated deviation, a pivoting device is actuated to adjust the strip position of the strip by pivoting the non-rotatable relative to one another about a common pivot pivotally coupled to the coating chamber coupled guide rollers tape positioning assembly. It is preferred when the band position reaches its middle position. In this preferred development, the correction of the tape transport comprises or consists at least in the reduction or elimination of transverse bends and in the displacement of the tape position towards the middle position of the tape.

The layer thickness sensor is preferably arranged behind the coating zone, viewed from the transport direction of the strip, while the distance sensor and/or the strip position sensor are preferably arranged behind the strip positioning arrangement, but in front of the coating zone.

The control is preferably carried out using empirically determined reference values which are stored on a control unit which is coupled both to the sensors mentioned and to the belt positioning arrangement.

As an alternative or in addition, the transverse sheet and/or the strip position is regulated with the layer thickness and/or with the spacing and/or with the strip position as the controlled variable.

Further details, features and advantages of the subject matter of the invention result from the following description in connection with the drawings, in which exemplary embodiments of the invention are shown by way of example.

It goes without saying that the features mentioned above and also explained below can be used not only in the combination specified in each case, but also in other combinations or on their own.

Show it:

1: Schematic representation of an embodiment of a coating system according to the invention in a side view;

Fig. 2: Schematic representation of a belt positioning arrangement of the coating system in the further development of the embodiment of FIG

tape transport direction as viewing direction (a) and in side view (b); figs 3 to 6: Representation of layer thickness distribution to clarify the correction of the belt positioning by means of the belt positioning arrangement.

1 shows a schematic representation of an embodiment of a coating system 1 according to the invention in a side view. The coating system 1 serves to coat a strip 2. For this purpose, the system has a coating chamber 3 with a chamber inlet 4 and a chamber outlet 5. The strip is transported through the chamber along the arrow 6 shown. Within the chamber there is preferably another coating channel, not shown in detail in FIG. 1, with heating means designed, for example, as heating coils, through which the strip 2 runs. The strip runs past a device 7 arranged in the coating chamber for vapor deposition of the material. This has a nozzle outlet 8 which is oriented toward the strip surface 9 to be coated. During coating, material vapor in a coating zone 10 impinges on the strip 2 passing through the coating zone 10 and forms a coating there as a result of condensation. In principle, it is also possible for sections of the device 7 for the gas-phase deposition of the material to be positioned outside the coating chamber 3 as long as the nozzle outlet 8 opens inside the coating chamber.

A tape positioning arrangement 11 is arranged in front of the coating zone 10 as viewed in the direction of tape transport 6 . On the first side of the belt, the belt positioning assembly 11 has a first guide roller 12 . A second guide roller 13 is arranged on the second side of the belt. The first guide roller and the second guide roller are positioned such that when the tape 2 is transported, both the first guide roller 12 and the second guide roller 13 are in contact with the tape 2 . In the embodiment shown, the axis of rotation of the second guide roller 13 is fixed, ie it does not change its position relative to the coating chamber. The first guide roller 12 can be moved at the point of contact of the strip in a direction perpendicular to the strip surface, ie it can be moved, for example, in the direction indicated by the circle 12', which would cause the strip to be deflected. For the movement, the guide roller 12 is coupled via a suspension 18 to an electromechanically controllable mechanism 19, the coupling being effected in a vacuum-tight manner by a bellows 20.

A layer thickness sensor 14 and a distance sensor 16 are arranged behind the coating zone, viewed in the direction of tape transport, which can be traversed with a corresponding layer thickness sensor adjustment mechanism 15 and a distance sensor adjustment mechanism 17 in the transverse direction of the tape.

The layer thickness sensor 14 and the distance sensor 16 are coupled to the belt positioning arrangement 11 via a control unit 21, more precisely to the electromechanically controllable mechanism 19 of the belt positioning arrangement 11.

figs 2a and 2b shows a further developed embodiment according to which the axes of rotation of the two guide rollers 12, 13 are coupled relative to one another in a rotationally fixed manner and pivotable about a common pivot point 22 with the coating chamber for changing a strip position of the strip 2 by means of an adjustment unit 23 of a pivoting device The pivoting device can be formed, for example, as a whole of a movable suspension and an adjustment unit 23, which is not shown in detail here.

FIG. 3 shows an example of how a coating system from FIG. 1 can be used in an advantageous manner. The tape points in the tape run at in Cross-strip direction homogeneous mass flow of the material vapor causes the strip to deviate from flatness in the cross-strip direction. There is a transverse bow, which in the example results in the center of the strip being at a greater distance from the nozzle outlet than at the strip edges. As FIG. 3c shows, this leads to a layer thickness inhomogeneity outside the tolerance band, which is the entirety of possible desired values (dashed area). By controlling the roller 12 to move it in the direction directed toward the belt, the transverse arc is largely eliminated due to the force exerted by the guide roller 12 on the belt (see FIG. 4b). The result is a layer thickness distribution within the tolerance band (see Fig. 4c).

FIG. 5 shows a constellation comparable to FIG. 3, it being evident from FIG. 5a that, in contrast to the constellation shown in FIG. 3a, there is an inhomogeneous distribution of the mass flow. The effect of the inhomogeneity of the mass flow due to the uneven distribution of the material vapor is superimposed on the effect of the transverse arc. In Fig. 6 it can be seen that achieving a homogeneous coating (Fig. 6c) is only possible in this case if a certain amount of transverse bow is retained (Fig.

6b). From this, the knowledge can be derived that the control or regulation of the flatness change by changing the position of the first guide roller 12 unfolds its advantages in a particular way if the determination of the layer thickness is used as a controlled variable. A coating system with a layer thickness sensor and a method for coating with the layer thickness as the control variable therefore represent particularly preferred embodiments of the present development.

Claims

patent claims

1. Coating system (1) for coating a strip (2), in particular a metallic strip (2), for example a steel strip, with a material that is present in the gas phase, the coating system having:

- a coating chamber (3) with a chamber inlet (4) and a chamber outlet (5) for transporting the strip (2) through the coating chamber (3),

- a device (7) for gas phase deposition of the material with an evaporation section for evaporating the material into the gas phase and with a nozzle section for guiding the material present in the gas phase to a nozzle outlet (8) of the nozzle section opening inside the coating chamber for discharge directed onto the strip of the material present in the gas phase in the direction of a strip surface (9) of the strip to be coated, in order to continuously supply material present in the gas phase to the strip surface (9) to be coated in a coating zone (10) through which the strip (2) is transported and to form a coating on the strip surface (9) by condensation,

- a tape positioning arrangement (11) arranged in front of the coating zone, seen in the direction of tape transport (6), for the continuous correction of the tape transport, the tape positioning arrangement (11) having at least one first guide roller (12) arranged on the first side of the tape and one on the second side of the tape arranged second guide roller (13), wherein the first guide roller (12) and the second guide roller (13) are positioned such that when transporting the tape (2) both the first Guide roller (12) and the second guide roller (13) are in contact with the belt (2).

2. Coating installation (1) according to claim 1, wherein the first guide roller (12) and the second guide roller (13) are spaced apart from one another in the belt transport direction (6).

3. Coating system (1) according to one of the preceding claims, wherein the belt positioning arrangement (11) is positioned immediately in front of the coating zone (10), ie preferably less than 11 meters from the coating zone (10).

4. Coating system (1) according to one of the preceding claims, wherein the axis of rotation of one of the two guide rollers (12,

13) is fixed or is designed to be fixed continuously during tape transport, and the axis of rotation of the other of the two guide rollers (12,

13) is movable at the point of contact of the belt (2) with the guide roller (12) in a direction perpendicular to the belt surface or in a direction with a directional component perpendicular to the belt surface.

5. Coating system (1) according to one of the preceding claims, wherein a layer thickness sensor (14), preferably designed as an X-ray fluorescence sensor, for non-contact determination of layer thickness values of the coating is positioned behind the coating zone (10), viewed in the belt transport direction (6).

6. Coating system (1) according to claim 5, wherein the layer thickness sensor (14) is movably positioned in a traversing manner, is arranged, for example, on the coating chamber (3) and can be moved by means of a layer thickness sensor adjustment mechanism (15) in order to determine layer thickness values designed as a layer thickness profile.

7. Coating system (1) according to one of the preceding claims, having a distance sensor (16) for determining distance values of the strip (2), preferably a distance sensor designed as an inductive or capacitive sensor, which is preferably seen in the strip transport direction (6) in front of the coating zone ( 10) is positioned.

8. Coating installation (1) according to claim 7, wherein the distance sensor (16) is positioned so that it can move traversing, for example arranged on the coating chamber, and can be moved by means of a distance sensor adjustment mechanism (17).

9. Coating system (1) according to one of claims 5 to 8, wherein the layer thickness sensor (14) and/or the distance sensor (16) is coupled to the belt positioning arrangement (11) via a control unit (21) and the control unit (21) is set up , the

Actuate a belt positioning arrangement (11) in order to set, preferably regulate, belt positioning as a function of detected layer thickness values and/or distance values.

10. Coating system (1) according to one of the preceding claims, wherein the axes of rotation of the two guide rollers (12, 13) coupled in a rotationally fixed manner relative to one another are coupled to the coating chamber (3) so as to be pivotable about a common pivot point (22) in order to change a strip position of the strip.

11. Coating system (1) according to claim 10, having a preferably optical strip position sensor which is arranged behind the strip positioning arrangement (11) in the direction of strip transport (6) and which is coupled via a control device to a pivoting device coupled to the strip positioning arrangement, wherein the The control device is set up to control the pivoting device for setting, preferably for regulating, the strip position as a function of the sensor signal from the strip position sensor.

12. Coating system (1) according to one of the preceding claims, wherein the device (7) for gas-phase deposition of the material is a jet vapor deposition device or the device (7) for gas-phase deposition of the material is designed with the evaporation section having a pre-evaporation section and a post-evaporation section preferably designed as a crucible, the pre-evaporation section having an injection head for preparing the coating material present as the starting material and an injector tube, the injector pipe being designed to conduct the coating material prepared in the injection head to the post-evaporation section and being coupled to the post-evaporation section for guiding the prepared coating material into bring the post-evaporation section into the gas phase there, with the spray head preferably being a wire spray gun for arc melting and/or arc evaporation of into the Dr starting material introduced by spraying, the coating rate being adjusted by a feed rate of a feed of starting material into the spray head.

13. A method for coating a strip (2) with a coating system (1), preferably according to one of claims 1 to 12, comprising the steps:

- transporting a strip (2) through a coating zone (10) of the coating system (1) for coating the strip surface (9), i) repeated or continuous determination of at least one of the following parameters: a) layer thickness value using a layer thickness sensor (14), b) distance value by means of a distance sensor (16); ii) continuously comparing the parameter to a target value; iii) if the at least one parameter deviates from the desired value by more than a tolerated deviation, control of a belt positioning arrangement (11) for adjusting the transverse arc of the belt (2), the belt positioning arrangement (11) having at least one first guide roller (12) and a second guide roller (13) arranged on the second side of the belt, the first guide roller (12) and the second guide roller (13) being positioned in such a way that when the belt (2) is being transported, both the first guide roller (12) and the second guide roller (13) are in contact with the belt and one of the two guide rollers (12) at the point of contact of the belt with the guide roller (12) can be moved in a direction perpendicular to the belt surface, iv) optionally: repeating the Steps ii) and iii) until the controlled achievement of the setpoint or a value that is less than a tolerated deviation, but no more than the tolerated deviation, from The target value deviates from the regulated setting of the cross bow of the belt (2).

14. The method according to claim 13, wherein in addition a strip position of the strip (2) is determined by means of a strip position sensor and if the strip position deviates from a desired value by more than a tolerated deviation, one with the

The pivot device coupled to the belt positioning arrangement (11) is actuated to adjust the belt position of the belt (2) by pivoting the guide rollers (12, 13) of the coating chamber which are non-rotatable relative to one another and pivotable about a common pivot point (22).

tape positioning assembly (11).

15. The method according to claim 13 or according to claim 14, wherein the control is based on empirically determined reference values that are stored on the control unit.