Coating system for coating a strip and method for coating a strip - Patents.com

Abstract

A coating system and method are provided that improve coating uniformity. The invention relates to a coating system for coating a strip 2, for example a steel strip, with a material present in a gas phase. The coating system comprises a coating chamber, an apparatus for depositing said material and a strip positioning assembly for correcting the strip transport. The strip positioning assembly comprises a first guide roller 12 and a second guide roller 13. In particular, a pivoting movement about a pivot axis 22 is possible, said pivoting being able to be performed by means of an adjustment 23. The invention also relates to a method for coating a strip 2.

Description

[Technical field]

[0001] The present invention relates to a coating system for coating a strip. The present invention also relates to a method for coating a strip. [Background technology]

[0002] Methods based on the so-called vapor deposition principle can be used to coat strips, in particular metal strips, such as steel strips. The vapor deposition principle consists in providing a starting material and converting it into a gas phase. The components of the material present in the gas phase, in particular atoms and / or ions, move through a coating chamber and are directed to the area where the coating takes place, hereinafter referred to as the coating zone. The strip is conveyed through the coating zone so that the components of the material in the gas phase precipitate on the strip to be coated, thus forming a coating.

[0003] The advantage of deposition is that it is possible to produce coatings very economically and to clearly influence the properties of said coatings to a high degree and within a wide range of properties. Another advantage of deposition is that it is suitable for producing coatings of many different materials. In contrast to other methods, deposition is suitable for producing coatings of high melting point materials, for example, or of materials in one or more metastable phases. [Prior art documents] [Non-patent literature]

[0004] Komarenko, P., et al. “Handbook of Deposition Technologies for Films and Coatings Science, Applications and Technology”, [online], 2010, pp. 881-901, [Retrieved April 23, 2021], Internet <URL:https: / / doi.org / 10.1016 / B978-0-8155-2031-3.00018-1> Summary of the Invention [Problem to be solved by the invention]

[0005] The invention relates to an apparatus for depositing a material, where the material converted into a gas phase is directed to a coating zone through a nozzle outlet of a nozzle portion of the apparatus for depositing a material.

[0006] The strip is guided through a device for deposition in a coating chamber and is coated with the components present in the gas phase emerging from the device. It is desirable here for the coating to be applied as uniformly as possible, i.e. in particular with a uniform thickness not only in the longitudinal direction of the strip but also in the transverse direction of the strip. Against the background that not only the transport of the strip itself is variable, but also the uniformity of the transfer of the materials present in the gas phase can vary depending on the specific conditions of the coating (material, nozzle geometry, etc.), the object of the invention is to improve the uniformity of the coating. [Means for solving the problem]

[0007] This object is achieved by a coating system having the features of claim 1 and by a method for coating a strip having the features of claim 13.

[0008] The coating system is also capable of coating the strip and for this purpose comprises the following components:

[0009] The coating system includes a coating chamber having a chamber inlet and a chamber outlet through which the strip to be coated passes and out of the chamber outlet. The coating chamber is typically a substantially sealed chamber in which, for example, 10(-3) It is preferable that a technical vacuum of between 100 mbar and 100 mbar, preferably less than 20 mbar, can be applied.

[0010] The coating chamber further comprises a device for depositing a material, the device for depositing comprising an evaporation section and a nozzle section, the evaporation section first evaporating a material provided as a starting material into a gas phase, and then the nozzle section directing the material present in the gas phase towards the strip surface to be coated, such that the gas phase particles flowing out of the nozzle outlet of the nozzle section flow towards the coating zone.

[0011] The starting material can be evaporated in a known manner, for example by thermal evaporation, arc evaporation, other evaporation or a combination of these. What is important in the context of the present invention is that after passing through the evaporation section, said material, which is present in the gas phase, is directed by the nozzle section towards the strip surface to be coated and condenses on reaching the strip surface.

[0012] The strip passes through a coating zone, which is the area of ​​contact between the strip, which is continuously conveyed through the coating chamber, and the material present in the gas phase: in conveying through said chamber, the strip thus moves continuously and is thereby continuously exposed to the material in the gas phase, so that the material in the gas phase condenses on the strip surface to form the desired coating.

[0013] Optionally, a coating channel can be arranged in the coating chamber, said coating channel being equipped with heating means for heating. The strip is conveyed through said coating channel at least in the region of the coating zone.

[0014] Throughout this specification, the terms "gas phase" and "evaporation" are used as they are also commonly used in the deposition field. In this case, the term "gas phase" may include the fact that a low weight fraction, for example 30% by weight or less, preferably 10% by weight or less, of material in the gas phase is not present in the strict physical sense, but instead exists as a vapor, as an aerosol, and / or as clusters. The term "evaporation" includes the fact that, depending on the material and the technology used, particles are transferred at least partially to the gas phase by mechanisms other than evaporation in the strict physical sense, for example sublimation. In the context of this specification, which is the context of language usage in the deposition field, the term "evaporation" includes evaporation in the strict physical sense, i.e., phase transition from liquid to gas, as well as other mechanisms, such as sublimation in particular. Similarly, materials present in the gas phase are also referred to synonymously as material vapor.

[0015] Viewed in the strip transport direction, the strip positioning assembly is arranged before the coating zone. The strip positioning assembly serves the purpose of contributing to a continuous correction of the strip transport. For this purpose, the strip positioning assembly comprises at least one first guide roller arranged on a first side of the strip and a second guide roller arranged on a second side of the strip. During the transport of the strip, not only the first guide roller but also the second guide roller are in contact with the strip, i.e. the first and second guide rollers are arranged such that the first guide roller is in contact with the first strip surface and the second guide roller is in contact with the second strip surface.

[0016] The strip positioning assembly comprises two guide rollers located before the coating zone, preferably both in contact with the strip surface, which correct the strip guidance of the strip just before the strip surface is coated with the material vapor. After passing through said positioning assembly, the run of the strip is closer to the exemplary and ideal run than before. In particular, the transverse curvature of the strip is closer to the desired state, i.e. the transverse curvature is preferably reduced, and particularly preferably eliminated. The term "transverse curvature" is known in the technical field of strip conveying. It means the deviation of the strip from the ideal strip surface in the form of a curvature in the strip cross section in the direction perpendicular to the conveying direction. Thus, a transverse curvature occurs if the strip surface does not form a straight line in cross section, but a circular arc-like curve. The aim is to minimize or completely eliminate the transverse curvature, which is achieved by the coating system according to the invention and its further developments. The procedure according to the invention advantageously ensures smaller changes in the lateral curvature of the strip within the coating zone throughout the coating time, resulting in a more uniform coating not only along the length of the strip but also across the strip, as compared to coatings performed without the use of a positioning assembly.

[0017] That is, the correction of the strip transport includes at least a correction of the lateral curvature, i.e., a reduction or elimination of the lateral curvature, which is performed by the guide rollers arranged on either side of the strip and in contact with the strip, i.e., the first guide roller and the second guide roller.

[0018] Preferably, the axis of rotation of one of the two guide rollers is fixed or is configured to be continuously fixed during the strip transport, and the axis of rotation of the other of the two guide rollers is movable in a direction perpendicular to the strip surface or in a direction having a component perpendicular to the strip surface at the contact point of the roller side with the strip. That is to say, the position of the guide roller in the direction perpendicular to the strip surface can be changed, so that depending on the selected axis of rotation position, the still rotatable guide roller influences the guiding of the strip in various ways, for example by moving its axis of rotation in a direction facing the strip with a slight deflection. The deflection is achieved in such a way that, when viewed from the top of the strip positioning assembly in the strip transport direction, the lower edge of the first guide roller is located below the upper edge of the second guide roller, if the first guide roller is considered as the upper guide roller regardless of its actual spatial position. For example, the movement of the axis of rotation in a direction perpendicular to the strip surface can be achieved by an adjustment designed for vacuum and arranged in the coating chamber. Here, electrical, pneumatic or mixed types of adjustments known to the expert can be provided. Alternatively, a mechanism located outside the coating chamber can be arranged in the coating system for a vertical movement relative to the strip surface. The inlet of the device which causes the movement is then designed as a lead-in for example of a metal rod into the vacuum chamber, which is preferably implemented vacuum-tight by means of a bellows.

[0019] For example, the guide roller on the nozzle outlet side can be fixed, while the roller of the strip opposite the nozzle outlet can be designed as a roller that can be moved perpendicularly to the strip surface. In a particularly advantageous embodiment, there is a degree of freedom of movement relative to the strip surface, and the movement of the guide roller that can be moved perpendicularly to the strip surface exerts a pressure on the strip surface perpendicular to the surface in combination with the counter pressure exerted by the fixed roller. Such an arrangement makes it possible to impose on the strip an increased force on the surface along the contact line of the guide roller lateral surface in the longitudinal direction relative to the axis of rotation of the guide roller, by increasing the deflection of the movable roller in the direction of the strip surface and exerting a pressure. This has the effect that the contour of the movably arranged roller and the strip are aligned in the transverse direction of the strip. For example, in the preferred case where the roller has a circular-cylindrical arc on its lateral surface, any transverse arc that may be present in the strip, i.e. the deviation of the transverse contour of the strip from a straight line, can be corrected or at least partially corrected. The fact that the guide rollers, which are movable perpendicularly to the strip surface, rotate with the movement of the strip means that corrective movements can be made throughout the entire coating process and, if necessary, along the entire length of the strip, so that after the coating process the coating of the strip has excellent uniformity in all directions on the strip surface.

[0020] Due to the fact that it is possible to move the movable guide roller relative to the fixed guide roller, the force acting perpendicular to the strip surface can be achieved with relatively uncomplicated means, i.e. by providing only one movable roller.

[0021] For example, in a preferred basic position in which the side of the movable guide roller and the side of the fixed guide roller are parallel to each other and have tangential planes parallel to the strip surface, the distance between which corresponds to the strip thickness, the force exerted by the movable roller is minimal. According to a further development, it is preferred that the other of the two guide rollers is movable in such a way that the movable roller is mounted so as to be movable from the abovementioned basic position in the direction of the half-space in which the non-movable roller is located, or in other words the rotation axis of the movable roller is movable in a direction perpendicular to the strip surface in such a way that it forces the strip onto the deflection path. This is done geometrically speaking by moving a plane parallel to the strip surface of the undeformed strip and containing the rotation axis of the movable guide roller towards a plane parallel to the surface of the undeformed strip and containing the fixed rotation axis, in such a way that the distance between these two planes is smaller than the sum of the two radii of the two guide rollers plus the strip thickness. As the rotation axis of the movable guide roller moves in the abovementioned direction, said distance decreases and the force acting on the strip surface increases accordingly, so that any existing transverse arcs can be gradually eliminated. This mechanism is a preferred variation of the strip positioning assembly, which allows for the elimination or reduction of lateral arcing of the strip being coated in a relatively uncomplicated manner.

[0022] It is particularly preferred if the first and second guide rollers are arranged in the coating system at a distance from each other, i.e. in such a way that, as viewed in the strip transport direction, the two lines of contact with the strip formed by the guide rollers are spaced from each other. In this way, the strip can be guided in a particularly advantageous manner. The transverse arcs of the strip can be eliminated or at least reduced, so that, ultimately, as viewed from the nozzle outlet, there are no concave or convex transverse arcs or the respective transverse arcs can be at least reduced compared to their magnitude prior to the positioning assembly.

[0023] The strip positioning assembly is preferably arranged just before the coating zone, i.e. the coating zone preferably starts at a point up to 11 meters, particularly preferably up to 4 meters, behind the strip positioning assembly. Arranging the strip positioning assembly just before the coating zone ensures that the strip positioning carried out for coating is more completely, or at least almost completely, guaranteed by reducing or eliminating the lateral arc at the coating point.

[0024] According to an advantageous development, it is provided that a layer thickness sensor is arranged behind the coating zone, seen in the strip transport direction. The layer thickness sensor is suitable for contact-free measurement of layer thickness values ​​of the already applied coating. For measuring and detecting layer thicknesses or layer thickness-dependent values, the sensor is therefore arranged towards the coating, preferably in a vertical direction of view. During strip transport, the strip passes the layer thickness sensor, so that layer thickness values, in particular layer thicknesses, are measured sequentially or continuously along the strip length. The measured values ​​can then be used to change the layer thickness in order to adjust, preferably regulate, the positioning of the strip, either singly, repeatedly or continuously. For example, if the measured thickness deviates from the target thickness or the relative change in the layer thickness exceeds a certain amount, the strip position can be adjusted or regulated. Alternatively or additionally, the coating can also be adjusted by changing the operation of the device for vapor deposition. For this purpose, the device for vapor deposition is preferably connected to the layer thickness sensor via a corresponding coating control device. It is particularly preferred that the layer thickness sensor is designed as an X-ray fluorescence sensor, since X-ray fluorescence sensors are inexpensive to obtain and can be operated with little effort and maintenance, and also because this provides a sufficiently high detection accuracy.

[0025] In a further development, the layer thickness sensor is arranged for transverse movement. For example, the layer thickness sensor is arranged in the coating chamber and can be moved by a layer thickness sensor adjustment mechanism. The layer thickness sensor adjustment mechanism can for example be designed to be vacuum-compatible and arranged in the coating chamber. The layer thickness sensor adjustment mechanism can for example be electrical or pneumatic. Alternatively, the layer thickness sensor adjustment mechanism can be arranged outside the coating chamber and connected to the coating chamber via a feed-through, for example by means of a bellows. The layer thickness sensor adjustment mechanism preferably comprises a motor for setting and / or adjusting the position of the layer thickness sensor in the transverse direction of the strip. The coating system detects the layer thickness values ​​by arranging the coating thickness sensor in the coating system for transverse movement as described above. The layer thickness values ​​comprise information about the layer thickness profile of the coating strip in the transverse direction of the strip. As a result, the coating system can detect deviations of the layer thickness profile from the desired or expected layer thickness profile, which deviations can be used to derive conclusions about unexpected characteristics of the strip positioning, in particular about non-uniformity in the application of material vapor to the strip by the deposition device, resulting from, for example, the formation of lateral arcs in the strip and / or possible non-uniformity of the material vapor discharged from the nozzle outlet.

[0026] Alternatively or additionally, in an expanded embodiment, the coating system may comprise a distance sensor, which may detect changes in distance from the sensor and thus may be used to detect changes in the travel of the strip, which may be caused by, for example, variations in strip tension. Knowing the measurements obtained by the distance sensor, the uniformity of the applied coating may be improved by adjusting the coating system, in particular by readjusting the strip positioning by the strip positioning assembly. For example, inductive or capacitive distance sensors, well known to those skilled in the art, may function as distance sensors.

[0027] If there is a distance sensor, it is arranged to detect the distance of the region of the strip running behind the strip positioning assembly as viewed in the strip transport direction. The distance sensor is preferably arranged in front of the coating zone to detect the distance of the region of the strip running in front of the coating zone as viewed in the strip transport direction. This has the advantage that the distance is measured in an area relatively close to the strip positioning assembly, so that depending on this distance the conditions are met for a particularly accurate adjustment or regulation of the strip positioning assembly.

[0028] If there is a layer thickness sensor, it is arranged to detect the layer thickness of the coating in the region of the strip which runs behind the coating zone as seen in the strip transport direction.

[0029] In a preferred development, the distance sensor is arranged transversely movable, for example arranged in the coating chamber and designed to be movable on the coating system by means of a distance sensor adjustment mechanism. Analogous to the above explanation related to the transverse movement of the layer thickness sensor, the distance sensor can not only track distance information for changes in the longitudinal position at a fixed transverse position of the strip, but can also detect distance information along at least a part of the transverse direction of the strip, preferably along the entire transverse direction of the strip, and thus detect a distance profile or changes in the distance profile that depend on the transverse positioning. This embodiment has the advantage that from the information obtained in this way, corrections of the positioning of the strip can be made in a particularly advantageous manner, thereby improving the coating uniformity.

[0030] According to one development, if there are layer thickness sensors and / or if there are distance sensors, the layer thickness sensors and / or the distance sensors are coupled to the strip positioning assembly via a control unit. The control unit is configured to read the values ​​of each of the one or more sensors, i.e. to read the layer thickness values ​​and / or distance values, and is configured to control the arrangement for strip positioning in order to adjust, preferably regulate, the strip positioning depending on the detected layer thickness values ​​and / or distance values. That is, the coating system comprises a control unit, which can receive data from the layer thickness sensors and / or distance sensors (depending on whether there is one or more of these sensors) and control the strip positioning assembly based on the transmitted values ​​in order to adjust the positioning of the strip. The positioning of the strip can be adjusted in particular by moving a guide roller that is movable in a direction perpendicular to the strip surface. For example, a guide roller that is movable in a direction perpendicular to the strip surface can be moved towards the strip in order to increase the force and correspondingly deflect the strip as it moves towards the strip, reducing any possible lateral arcs. A corresponding device in the control unit can be implemented, for example, to store in the control unit data records obtained on the basis of experiments, said data records relating the dependence between the position of the guide roller movable in a direction perpendicular to the strip surface and the change in the lateral arc with the change in the position of said guide roller. Alternatively, however, the control unit can simply be arranged to execute a control loop on the basis of a corresponding program sequence, said control loop functioning by using the layer thickness and / or distance as control variables, changing the position of the guide roller movable in a direction perpendicular to the strip surface after detecting a deviation of the control variables from the corresponding set value, and then determining based on the subsequently redetected control variables whether a further change in the position of the guide roller movable in a direction perpendicular to the strip surface is necessary and how to execute this change in position.In other words, a further development is provided as a coating system in which a change in position of a moveable roller of a strip positioning assembly is a manipulated variable for controlling a control variable selected as layer thickness and / or distance.

[0031] In order to be able to adjust, preferably regulate, the transverse arc, the coating system preferably comprises a transversely movable layer thickness sensor for adjustment, preferably regulation, based on the measured layer thickness profile. Instead of a transversely movable layer thickness sensor, there may also be two or more layer thickness sensors, preferably at least three layer thickness sensors, which are arranged at suitable longitudinal positions of the strip behind the coating zone, pointing at different, for example equidistant, positions in the transverse direction of the strip. This embodiment ensures that the layer thickness profile is obtained without the need for a transversely movable layer thickness sensor.

[0032] Alternatively or additionally, the axis of rotation of the first guide roller and the axis of rotation of the second guide roller can be connected to each other in a rotatably fixed manner via a mechanical connection, i.e. both guide rollers are arranged at an angle to each other and preferably parallel to each other, whereas the mechanical connection itself is pivotally mounted, said pivoting preferably taking place on a pivot axis parallel to the strip conveying direction. Thus, in this embodiment, the strip positioning assemblies, i.e. the first guide roller and the second guide roller, can be pivoted together about a pivot axis without changing their orientation relative to each other with respect to the angle to each other. Said pivoting is performed, for example, by a pivoting device connected to the strip positioning assembly. The pivoting device as a whole can be formed, for example, from an adjustment part and a connecting element, such as a connecting rod between the adjustment part and the strip positioning assembly. The adjustment part engages, for example, in the mechanical connection, by which the first guide roller and the second guide roller are connected to each other at a position on the strip side further away from the pivot axis, so that the first guide roller and the second guide roller are pivoted by adjusting the adjustment part, which is designed, for example, as a lifting rod. The adjustment for the rotary movement can be designed, for example, for vacuum and arranged in the coating chamber, but can also be provided outside the sealing chamber. The adjustment is preferably designed pneumatically or electrically as an electric motor. The advantage is that the strip positioning assembly can be pivotally assembled by the joint pivoting of the rotary shafts arranged rotatably fixed relative to one another, whereby deviations of the strip position from the ideal strip center position can be corrected. This directly results in an improvement of the layer uniformity, especially in the layer thickness distribution.

[0033] In the context of this specification, the strip position means the side of the guide roller that conveys the strip, as seen in the direction of the rotation axis. By pivoting the strip positioning assembly, the strip position is corrected to the desired part. It is preferable that the strip is guided to the center of the side of at least one roller, preferably the center of all rollers, of the non-pivotable rollers of the strip run, which is referred to in the context of this specification as the case where the strip center position is preferably desired.

[0034] In a particularly preferred embodiment, the axis of rotation of at least one of the two guide rollers at the contact point between the strip and the guide roller is movable in a direction perpendicular to the strip surface or in a direction having a component perpendicular to the strip surface relative to the other guide roller, and the strip positioning assembly is pivotally mounted, such an arrangement not only allows lateral curvature to be prevented or largely prevented by the same device, but also has the further advantage of allowing the central position of the strip to be maintained over a wide range or even completely.

[0035] In the case where the coating system is pivotable by the coating chamber and has guide roller rotation axes connected to each other in a rotatably fixed manner, it is particularly preferred that the coating system also comprises an optical strip position sensor arranged downstream in the strip conveying direction from the strip positioning assembly and connected to the pivoting device via a control device. The control device is arranged to control the pivoting device to adjust, preferably regulate, the strip position by pivoting the strip positioning assembly depending on a sensor signal from the strip position sensor. For example, this can be done by storing experimentally obtained data in a memory area of ​​the control device, and performing the pivoting in response to a deviation of the strip position from the strip center position detected by the sensor and by activating a corresponding available motor, for example an electric motor. The control device for adjusting, preferably regulating, the pivoting of the strip positioning assembly to bring the strip position towards or close to the strip center position can also be realized as a separate second control device independent of the control device for controlling the relative positions of the guide rollers to each other, but it can also be a separate memory area of ​​the control device.

[0036] The apparatus for depositing the material is preferably a jet deposition apparatus.

[0037] The term jet deposition apparatus is understood by those skilled in the art to mean, for example, an apparatus in which a coating material is thermally converted into a gas phase in a crucible and then transported to a substrate by a gas flow, typically together with a carrier gas flow of an inert gas, but in some embodiments also as a gas flow consisting only of the material converted into a gas phase, preferably at a gas flow velocity exceeding the sonic speed, particularly preferably at a gas flow velocity exceeding 500 m / s. The mode of operation is described, for example, in the review "Handbook of Deposition Technologies for Films and Coatings Science, Applications and Technology" (2010, pp. 881-901, https: / / doi.org / 10.1016 / B978-0-8155-2031-3.00018-1) (linked to the filing date).

[0038] The surface to be coated is usually placed under an atmosphere of negative pressure relative to the atmosphere in the crucible. The surface to be coated is preferably, for example, under a pressure of less than 100 mbar, for example 10 (-3) The coating is then placed in a technical vacuum with a pressure of 10-20 mbar, which in large-scale implementations is a good compromise between good properties of the coating and the effort required to generate and maintain the vacuum.

[0039] The JVD process has advantages in particular in the large area coating of strip, in particular of strip metal, for example strip steel. One advantage of the JVD process is that it is possible to coat the strip at a high coating rate by directing the material present in the evaporated gas phase at a relatively high pressure onto the surface, which brings the advantage that the coating of the strip is economically viable, for example by means of a correspondingly selected high strip speed.

[0040] In an alternative preferred development, the device for depositing materials is formed with an evaporation section, which comprises a front evaporation section and a rear evaporation section, preferably designed as a crucible, the front evaporation section comprises a spray head and an injection tube for preparing a coating material as starting material, the injection tube being designed to guide the coating material prepared in the spray head to the rear evaporation section and introduce the prepared coating material therein for conversion into the gas phase.

[0041] The spray head is preferably a wire sprayer, which is intended for arc melting and / or arc evaporation of the starting material introduced into the wire sprayer. The material used to form the respective coating is, for example, in the form of a wire or strip. The starting material is introduced into the range of influence of the electric arc, where preferably there are two wires or two strips of starting material, one of the two being connected to a DC voltage source as a cathode and the other being connected to a DC voltage source as an anode, and a voltage sufficient to form an arc is set at the DC voltage source. The material melted and / or evaporated by the arc energy flows from the gas or gas mixture through an inlet by a gas flow into the interior of the so-called crucible chamber and is heated to a temperature at least equal to the evaporation temperature of at least one material used for the coating or to the evaporation temperature of the material with the highest evaporation temperature. In this case, the material in the crucible is completely evaporated and / or is discharged through the opening of the crucible. The respective evaporated material comes into contact with the surface to be coated of the strip-shaped material part or workpiece part to form the respective coating.

[0042] The evaporation back section preferably comprises a nozzle section connected thereto, the nozzle section having and terminating in a nozzle outlet.

[0043] In special cases where the release rate of the material released from the post-evaporation portion is correspondingly high, the above-mentioned alternative embodiment may be considered as a modification of the JVD.

[0044] An aspect of the invention relates to a method for coating a strip with a coating system, which can be carried out, for example, with a coating system of the type mentioned at the beginning or one of its developments, comprising at least the steps given below:

[0045] Conveying the strip through a coating zone of a coating system, where a strip surface of the strip is coated.

[0046] During coating, repeatedly or continuously measuring one of the following parameters: a) Layer thickness values ​​from a layer thickness sensor. The layer thickness values ​​can be, for example, layer thicknesses or layer thickness profiles. b) Distance values ​​from a distance sensor. The distance values ​​can be, for example, a distance or a distance profile.

[0047] Continually comparing the parameter with a set value, which may be, for example, a comparison value, a comparison curve, or a set of curve parameters.

[0048] activating a strip positioning assembly to adjust the lateral arc of the strip when at least one parameter deviates from a set value by more than an allowable deviation, wherein the strip positioning assembly comprises at least a first guide roller arranged on a first side of the strip and a second guide roller arranged on a second side of the strip, the first guide roller and the second guide roller being arranged such that both the first guide roller and the second guide roller are in contact with the strip during transport of the strip, and one of the two guide rollers is movable in a direction perpendicular to the strip surface at a contact point between the strip and said guide roller.

[0049] An optional step of repeating the two previous steps to control and adjust the lateral arc of the belt until a set value is reached in a controlled manner or until the deviation of the value from the set value is less than and does not exceed the allowable deviation.

[0050] Controlling or adjusting the lateral arc by varying the position of the movable first guide roller has advantages in the special case of using a measured coating thickness as control variable. Therefore, a coating system with a coating thickness sensor and a method for coating with layer thickness as control variable are particularly preferred embodiments in this development.

[0051] In a further preferred development of the method, the strip position of the strip is measured by an existing strip position sensor and, if the strip position deviates from a set value, preferably from the strip centre position, by more than an allowable deviation, a pivoting device is activated to adjust the strip position of the strip by pivoting guide rollers of a strip positioning assembly, said guide rollers being connected to the coating chamber such that they can pivot relative to each other in a rotatably fixed manner about a shared pivot axis. Preferably, the strip position has reached the strip centre position. In this preferred development, the correction of the strip transport at least comprises or consists of a displacement of the strip position towards the strip centre position as well as a reduction or elimination of the lateral arc.

[0052] The layer thickness sensor is preferably arranged after the coating zone when viewed in the transport direction of the strip. The distance sensor and / or the strip position sensor is preferably arranged after the strip positioning assembly and before the coating zone.

[0053] Action is preferably based on empirically determined reference values ​​stored in a controller coupled to the belt positioning assembly as well as the sensors described above.

[0054] Alternatively or additionally, layer thickness, distance and / or strip position are used as control variables to control the lateral arc and / or strip position.

[0055] Further details, features and advantages of the subject matter of the invention are given, by way of example, in the following description in conjunction with the drawings which represent embodiments of the invention.

[0056] It goes without saying that the features mentioned above and below can be used not only in the combinations presented, but also in other combinations or alone. [Brief description of the drawings]

[0057] The drawings are as follows: [Figure 1] FIG. 1 is a schematic side view of one embodiment of a coating system according to the present invention. [Diagram 2] FIG. 2 shows a schematic view of the strip positioning assembly of the coating system in a development of the embodiment shown in FIG. 1, seen in the strip transport direction (a) and in a side view (b). [Diagram 3] FIG. 3 is a layer thickness distribution diagram illustrating the correction of strip positioning using the strip positioning assembly. [Figure 4] FIG. 4 is a layer thickness distribution diagram illustrating the correction of strip positioning using the strip positioning assembly. [Diagram 5] FIG. 5 is a layer thickness distribution diagram illustrating the correction of strip positioning using the strip positioning assembly. [Figure 6] FIG. 6 is a layer thickness distribution diagram illustrating the correction of strip positioning using the strip positioning assembly. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] FIG. 1 is a schematic side view of an embodiment of a coating system 1 according to the invention. The coating system 1 serves to coat a strip 2. For this, said system comprises a coating chamber 3 with a chamber inlet 4 and a chamber outlet 5. The strip is transported through the chamber along the indicated arrow 6. Although not shown in detail in FIG. 1, preferably a separate coating channel is arranged in the chamber and comprises heating means designed as a heating coil or the like, through which the strip 2 passes. Said strip passes an apparatus 7 arranged in the coating chamber for depositing material. Said apparatus comprises a nozzle outlet 8, which is directed towards the strip surface 9 to be coated. During coating, material vapor in the coating zone 10 comes into contact with the strip 2 passing through the coating zone 10 and condenses to form a coating thereon. In principle, part of the apparatus 7 for depositing material can be arranged outside the coating chamber 3, as long as the nozzle outlet 8 opens in the coating chamber.

[0059] A strip positioning assembly 11 is arranged before the coating zone 10 in the strip conveying direction 6. The strip positioning assembly 11 comprises a first guide roller 12 on a first side of the strip. A second guide roller 13 is arranged on a second side of the strip. The first and second guide rollers 12 and 13 are arranged such that both are in contact with the strip 2 during conveyance of the strip 2.

[0060] In the illustrated embodiment, the axis of rotation of the second guide roller 13 is fixed, which means that its position relative to the coating chamber does not change. The first guide roller 12 is movable in a direction perpendicular to the strip surface at the contact position of the strip, so that it can be moved, for example, in the direction of the position shown by the circle 12', which causes a deflection of the strip. For this movement, the guide roller 12 is connected via a suspension 18 to an electromechanically actuable mechanism 19, which is then connected in a vacuum-tight manner by a bellows 20.

[0061] As seen in the direction of strip transport behind the coating zone, the layer thickness sensor 14 and the distance sensor 16 are arranged so that they can be displaced transversely in the transverse direction of the strip by means of corresponding layer thickness sensor adjustment mechanisms 15 and distance sensor adjustment mechanisms 17 .

[0062] The layer thickness sensor 14 and the distance sensor 16 are coupled via a control unit 21 to the strip positioning assembly 11 , more precisely to an electromechanically actuable mechanism 19 of the strip positioning assembly 11 .

[0063] 2a and 2b show an expanded embodiment, in which the rotation axes of the two guide rollers 12, 13 are connected in a rotatably fixed manner to one another about a common pivot axis 22 so as to be pivotable with the coating chamber for changing the strip position of the strip 2 by means of an adjustment part 23 of the pivot device. Although not shown here in detail, the pivot device can be designed, for example, as a movable suspension and as the whole of the adjustment part 23.

[0064] FIG. 3 illustrates how the coating system of FIG. 1 can be used in an advantageous manner. If the mass flow rate of the material vapor is uniform across the strip, the strip will exhibit deviations of the strip from a flat position across the strip, i.e. a transverse arc, which in the relevant example results in a greater distance from the nozzle outlet at the strip's center than at its edges. As shown in FIG. 3c, this leads to a non-uniform layer thickness outside the acceptable strip range, which is the sum of the possible settings (dashed area). By actuating the roller 12 so that it moves in a direction towards the strip, the force exerted by the guide roller 12 on the strip will almost eliminate the transverse arc (see FIG. 4b). As a result, an acceptable layer thickness distribution in the strip is obtained (see FIG. 4c).

[0065] FIG. 5 shows a configuration that can be compared to FIG. 3. FIG. 5a shows, in contrast to the configuration shown in FIG. 3a, an inhomogeneous distribution of the mass flow rate. The result of an inhomogeneous mass flow rate due to an inhomogeneous distribution of the material vapor overlaps with the result of the transverse arc. According to FIG. 6 it can be seen that it is only possible to obtain a uniform coating (FIG. 6c) if a certain level of the transverse arc is maintained (FIG. 6b). From this it can be concluded that controlling or regulating the change in the flat position by changing the position of the first guide roller 12 is particularly advantageous when the measured layer thickness is used as a control variable. A coating system with a layer thickness sensor and a method for coating with the layer thickness as a control variable are therefore particularly preferred embodiments of the present development.

Claims

1. A coating system (1) for coating a metal strip (2) with a material in a gas phase, said coating system (1) comprising: a coating chamber (3) having a chamber inlet (4) and a chamber outlet (5) for conveying said strip (2) through the coating chamber (3); An apparatus (7) for depositing the material, an evaporation section that evaporates the material into the gas phase; a nozzle section having a nozzle outlet (8) opening into the coating chamber (3), for directing the material in the gas phase to the nozzle outlet (8) and for ejecting the material in the gas phase toward the strip in the direction of a strip surface (9) to be coated of the strip; a coating zone (10) through which the strip (2) is conveyed, the device (7) for continuously contacting the strip surface (9) to be coated with a material in the gas phase and forming a coating on the strip surface (9) by condensation; a strip positioning assembly (11) for continuously correcting the strip transport, the strip positioning assembly (11) being arranged before the coating zone in the strip transport direction (6), the strip positioning assembly (11) comprising at least one first guide roller (12) arranged on a first side of the strip and a second guide roller (13) arranged on a second side of the strip, the first guide roller (12) and the second guide roller (13) being arranged such that both the first guide roller (12) and the second guide roller (13) are in contact with the strip (2) during transport of the strip; A coating system (1).

2. the first guide roller (12) and the second guide roller (13) are spaced apart from each other in the strip conveying direction (6); A coating system (1) according to claim 1.

3. the strip positioning assembly (11) is located less than 11 meters away from the coating zone (10); A coating system (1) according to claim 1 or 2.

4. The rotation axis of one of the two guide rollers (12, 13) is fixed or is configured to be continuously fixed during strip transport, the rotation axis of the other of the two guide rollers (12, 13) is movable in a direction perpendicular to the strip surface at the contact point between the strip (2) and the first guide roller (12) or in a direction having a component perpendicular to the strip surface; A coating system (1) according to any one of claims 1 to 3.

5. a layer thickness sensor (14) designed as an X-ray fluorescence sensor is arranged behind the coating zone (10) in the strip transport direction (6) and measures the layer thickness values ​​of the coating without contact. A coating system (1) according to any one of claims 1 to 4.

6. the layer thickness sensor (14) is arranged so as to be transversely movable, the layer thickness sensor (14) being arranged in the coating chamber (3) and movable by a layer thickness sensor adjustment mechanism (15) and measuring layer thickness values ​​which are formed as a layer thickness profile. A coating system (1) according to claim 5.

7. a distance sensor (16) for measuring a distance value of the strip (2), the distance sensor (16) being arranged before the coating zone (10) as seen in the strip conveying direction (6); A coating system (1) according to any one of the preceding claims.

8. The distance sensor (16) is designed as an inductive sensor or a capacitive sensor. A coating system (1) according to claim 7.

9. the distance sensor (16) is disposed in the coating chamber and is transversely movable by a distance sensor adjustment mechanism (17); A coating system (1) according to claim 7 or 8.

10. the layer thickness sensor (14) and / or the distance sensor (16) are coupled to the strip positioning assembly (11) via a control unit (21), the control unit (21) being configured to operate the strip positioning assembly (11) to adjust or regulate the strip positioning depending on the detected layer thickness values ​​and / or distance values. A coating system (1) according to any one of claims 5 to 9.

11. the rotation axes of the two guide rollers (12, 13) are connected in a rotatable and fixed manner relative to each other about a common pivot axis (22) so as to be pivotally connected to the coating chamber (3) for varying the strip position of the strip; A coating system (1) according to any one of the preceding claims.

12. Preferably comprising an optical strip position sensor; the optical strip position sensor is arranged downstream of the strip positioning assembly (11) in the strip transport direction (6) and is connected to a pivot device connected to the strip positioning assembly via a control device, the control device being configured to operate the pivot device to adjust or regulate the strip position in response to a sensor signal of the strip position sensor; A coating system (1) according to claim 11.

13. the device (7) for depositing the material is a jet deposition device, or The device (7) for depositing the material is formed with the evaporation section, the evaporation section having a front evaporation section and a rear evaporation section, the rear evaporation section being formed as a crucible, The evaporation front has a spray head for preparing the coating material present as a starting material, and an injection tube, the injection tube being designed to guide the coating material treated by the spray head to the evaporation rear and connected to the evaporation rear so as to guide the treated coating material into the interior of the evaporation rear and convert the coating material into the gas phase; the spray head being a wire sprayer into which the starting material is introduced and which arc melts and / or arc evaporates the starting material; The coating speed is adjusted by the input speed of the starting material into the spray head; A coating system (1) according to any one of the preceding claims.

14. The metal strip (2) is a steel strip. A coating system (1) according to any one of the preceding claims.

15. A method for coating a strip (2) with a coating system (1), said coating system (1) being a coating system (1) according to any one of claims 1 to 14, said method comprising the steps of: - conveying said strip (2) through a coating zone (10) of said coating system (1) for coating said strip surface (9); i) repeatedly or continuously measuring at least one of the following parameters, said parameters being: a) the layer thickness value from the layer thickness sensor (14), and b) distance value from the distance sensor (16); and ii) continuously comparing said parameter with a target value; iii) activating a strip positioning assembly (11) to adjust the lateral arc of the strip (2) if the at least one parameter deviates from a set value by more than an allowable deviation, the strip positioning assembly (11) comprising at least one first guide roller (12) arranged on a first side of the strip and a second guide roller (13) arranged on a second side of the strip, the first guide roller (12) and the second guide roller (13) being arranged such that both the first guide roller (12) and the second guide roller (13) are in contact with the strip during transport of the strip (2), one of the two guide rollers (12) being movable in a direction perpendicular to the strip surface at the contact point between the strip and the guide roller (12); iv) an optional step of repeating steps ii) and iii) in order to control and adjust the transverse arc of the strip (2) until the set value is reached in a controlled manner or until the deviation of the value from the set value is less than and does not exceed the allowable deviation; A method comprising:

16. and measuring a strip position of the strip (2) by a strip position sensor, and if the strip position deviates from a target value by more than an allowable deviation, adjusting the strip position of the strip (2) by operating a pivot device connected to the strip positioning assembly (11) by pivoting the guide rollers (12, 13) of the strip positioning assembly (11), the guide rollers (12, 13) being rotatably fixed relative to each other and capable of being pivotally connected to the coating chamber about a common pivot axis (22). The method of claim 15.

17. Executing the operation based on empirically determined reference values ​​stored in the control unit. The method according to claim 15 or claim 16.

18. The metal strip (2) is a steel strip. The method according to any one of claims 15 to 17.

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