Method and device for monitoring thickness profile of film web

Abstract

The invention relates to a method for monitoring a thickness profile (DP) of a film web (FB) in a transverse direction (QR) by means of a plurality of adjusting devices (120) for adjusting a gap opening (112) of an outlet nozzle (110) of a film flattening machine (100), comprising the following steps: detecting a thickness profile (DP) in the transverse direction (QR) of the film web (FB) transverse to a production direction (PR) of the film flattening machine (100); comparing at least a portion of the measured thickness profile (DP) with the target profile (VP); determining at least one local contour deviation (PA) in the deviation section (AA) as a result of the comparison; according to the invention, at least one control intervention is generated for adjusting at least one of the adjusting means (120) in an intervention section (EA) that differs from the deviation section (AA), in particular in order to avoid or reduce profile deviations in order to avoid the formation of piston rings or undesired thick and / or thin points in the edge portion of the film web.

Description

[0001] This application is a divisional application of the Chinese patent application entitled “Method and device for monitoring the thickness profile of a film web” and application number 2019800713692. Technical Field

[0002] The invention relates to a method for monitoring the thickness profile of a film web and a monitoring device for carrying out such a method. Background Art

[0003] It is known to use a flat film machine to produce film products. For this purpose, the flat film machine is designed to have a plurality of extrusion devices, which can provide the layers of the film web with similar, identical or different flowable extrusion materials. In general, the film web will have a plurality of layers that are different from each other, so that the film web can have different qualities and different functional properties depending on the material composition and the layer composition. Here, for the quality of the produced film web, it is especially important that the film web has a thickness distribution that is specified in the longitudinal and transverse directions. Especially in the transverse direction related to the conveying direction of the film machine or the production direction of the film machine, a sudden change in thickness in the thickness profile is dangerous or leads to a decrease in quality. Because the flat film web is usually wound onto a winding shaft later, small differences in the thickness profile may also accumulate, because they are always superimposed at the same position when winding. There is the following danger, that is, the so-called piston ring appears, which makes the film formed in a way that is not up to standard or even makes the film web unusable. In addition, the melt can also be coated or laminated. Therefore, for example, one or more flat webs can be supplied to the melt for this purpose.

[0004] In the known solutions, the thickness profile in the transverse direction of the film web is monitored manually or automatically and adjusted accordingly by means of an adjusting mechanism at the outlet nozzle of the film device. The change of the nozzle outlet gap at such an outlet nozzle can be carried out by means of one or more control interventions at an adjusting mechanism, for example in the form of a heat-sensitive pin. As a control intervention, a defined preset temperature, a preset voltage or a heating time can lead to a thermal expansion of the corresponding adjusting screw, thereby reducing the outlet gap by mechanical action on the nozzle lip. When the temperature at such an adjusting screw is reduced, the opposite process occurs.

[0005] The disadvantage of the known solutions is that the cross-effects are not taken into account when setting the adjustment mechanism or are only taken into account in an artificial way. In other words, the control of the adjustment mechanism is also performed only at the points where the desired effect is to be achieved in the thickness profile. Summary of the invention

[0006] The object of the present invention is to at least partially eliminate the above disadvantages. In particular, the object of the present invention is to provide a faster, more effective and / or better monitoring possibility for the thickness profile of a film web in a cost-effective and simple manner.

[0007] The aforementioned object is achieved by a method having the features of claim 1 and a monitoring device having the features of claim 17. Further features and details of the invention are derived from the dependent claims, the description and the drawings. Features and details described in connection with the method according to the invention are of course also applicable in connection with the monitoring device according to the invention and vice versa, so that reference is always made to each other or can be made to each other with regard to the disclosure of the individual inventive aspects.

[0008] The method according to the invention is used to monitor the thickness profile of a film web in the transverse direction by means of a plurality of adjustment mechanisms for adjusting the gap opening of the outlet nozzle of a flat film machine. To this end, the method comprises the following steps:

[0009] - Transverse to the production direction of the flat film machine to detect the thickness distribution along the transverse direction of the film web,

[0010] - comparing at least a portion of the measured thickness profile with a target profile,

[0011] - as a result of the comparison, determining at least one local contour deviation within the deviation section,

[0012] At least one control intervention is generated for adjusting at least one of the adjusting elements in an intervention section that differs from the deviation section.

[0013] The method according to the invention therefore aims in a known manner at ensuring monitoring of the thickness profile of a film web. In particular, corresponding target values ​​or target profiles should be adhered to. As with the known methods, this allows the thickness profile or profile deviations to be kept within certain limits, so that the quality of the film web meets high quality requirements. In particular, profile deviations above corresponding profile target values ​​can be avoided or reduced, so that the formation of so-called piston rings or undesirable thick and / or thin spots in the edge section of the film web, as described at the beginning, can be avoided.

[0014] However, in contrast to the monitoring possibilities used hitherto, the method according to the invention is based on a defined difference between the location of local profile deviations and the location of control interventions for adjusting at least one adjusting mechanism. When monitoring the thickness profile, monitoring is essentially continuous. The thickness profile can thus be measured simultaneously over the entire film web width or also sequentially with a shift in the transverse direction. The corresponding determination can be carried out in very different ways, for example by means of transmission sensors, by feedback of temperature information from the film web on a cooling roller or by other thickness measuring systems. As soon as the thickness profile is complete in the transverse direction, the detection is repeated, so that in the sense of the invention the thickness profile can be detected continuously or essentially continuously in the transverse direction.

[0015] By means of corresponding determination possibilities and by comparison with the target profile, the thickness profile in each local section can be evaluated with respect to the thickness profile quality. As soon as the profile deviation relative to the target profile in the local section is large or outside the target profile, the local section in which the profile deviation is located can be defined as a deviation section as a result in the sense of the invention. Therefore, based on the local profile deviation, the location of the local profile deviation in the form of a deviation section is also used as the basis for subsequent control intervention. Now, on the one hand, the subsequent control intervention is generated qualitatively and also by the location of the local profile deviation based on the local profile deviation, i.e., for example, whether it is an undesirable thin point or thick point in the thickness profile at this time. That is, in contrast to the known solutions, the control intervention is now not carried out in or at least not only in the deviation section, but on the contrary in the intervention section that is different from the deviation section. It should also be pointed out here that, as will be explained in more detail later, the intervention section and the deviation section can obviously have common parts in an overlapping manner. However, as will be described below, the following solution is preferred, in which the intervention section is formed separately or substantially separately from the deviation section.

[0016] According to the invention, control interventions can now be taken at locations other than where the local profile deviations are located. There are many new monitoring possibilities for this. In particular, cross-correlations can be taken into account in the control interventions, i.e. the influence of the regulating mechanism on the adjacent areas of the thickness profile. To illustrate this, the following example briefly describes such an adjustment. If a thin point in the thickness profile with a local profile deviation higher than the target profile is detected by monitoring according to the method, this leads to a corresponding control intervention. The purpose of the control intervention is to avoid undesirable thin points again, that is, to achieve a thickness increase, i.e. thickening, precisely in the local section where the profile deviation is located, i.e. in the deviation section. For this purpose, more material must flow into the deviation section than was the case when the thickness profile was determined. According to the invention, the control intervention can now adjust at least one regulating mechanism next to the deviation section so that a reduction in the nozzle outlet gap is achieved or generated next to the thin point. Now, the reduction in the nozzle outlet gap leads to the possibility that the less fluid extruded material of the film web can flow out there. More precisely, in the case of the same extruded material volume flow, the extruded material discharged in this way is distributed to the sections next to the intervention section, in particular to the left and right sides. Since the control intervention already takes this proximity relationship between the intervention segment and the deviation segment into account when selecting the adjusting mechanism and when defining the intervention segment, the discharged extrusion material now flows into the region of the deviation segment and leads to the desired filling of the thin spot.

[0017] It can therefore be concluded that within the scope of the invention, intervention is carried out by means of a control intervention explicitly at a position different from the position at which the deviation in the form of a local contour deviation is located. This transverse correlation, i.e. the offset arrangement of the control intervention, leads to a better, faster and more efficient elimination of the local contour deviation both qualitatively and quantitatively. In particular, such transverse influences when carrying out the control intervention can be predetermined and taken into account in the control intervention itself, so that undesirable control or regulation fluctuations can be reduced or even completely avoided.

[0018] According to the invention, it is advantageous if, in the method according to the invention, the intervention section has a different extension in the transverse direction than the deviation section, in particular a greater extension than the deviation section. This results in a large-area adjustment being possible, so that a continuous, in particular a more gradual influence can be provided by adjusting a large-area number of adjusting means. While in the known solutions a small number of adjusting means should provide a significant influence on the respective local contour deviation, a significantly greater extension can now be provided by means of a separate intervention section, so that a more gradual and in particular less fluctuating adjustment of the control intervention or the reduction of the local contour deviation can be achieved at the adjusting means with a smaller adjustment stroke.

[0019] It is also advantageous that in the method according to the invention at least two regulating mechanisms are regulated in the intervention section by the monitoring mechanism, in particular with different regulating qualities. Thus, these regulating mechanisms, in particular in the form of thermosensitive pins, are arranged side by side at uniform or substantially uniform intervals. The response of two or more regulating mechanisms now results in that, in particular in combination with a large extension of the intervention section according to the previous paragraph, a stepped regulation or a gentle adaptation of the regulation can be achieved. Different regulation qualities can, for example, result in control interventions of different strengths being carried out in the intervention sections, so that the regulation can result in a smoother transition between the regulated section and the non-regulated section in a stepped manner or with different strokes.

[0020] Advantages also result when the intervention section overlaps the deviation section in the film web transverse direction in the method according to the invention. This means that the deviation section and the intervention section have a common overlap with each other. Although the entire control intervention is applied in the intervention section and therefore at least partially next to the deviation section, a continuous transition is provided here between the deviation section and the intervention section, so that space is left for molten material, especially in the region of the deviation section. In this embodiment, however, the deviation section is designed to be at least partially free of such control intervention, so that space is left accordingly for providing molten material when moving to an adjacent region or for accommodating molten material due to moving in from an adjacent region.

[0021] Further advantages are achieved when, in the method according to the invention, the intervention section is located immediately or substantially immediately adjacent to the deviation section in the transverse direction of the film web. The immediate proximity or lateral abutment results in that, in particular in such a two-sided abutment combination, the deviation section is so to speak surrounded by the intervention section. Local deviations can thus be monitored or controlled and / or regulated in a compact and synchronous manner. Furthermore, the immediate proximity results in a simpler and more direct possibility of correlation between intervention situations and deviation situations.

[0022] Further advantages result when, in the method according to the invention, the intervention segment is spaced apart from the deviation segment in the transverse direction of the film web. Here, it can be said that there is a safety distance between the local deviation point and the intervention segment in order to avoid or reduce undesired overregulation or transient regulation fluctuations. It should also be pointed out that in the adjustment method, different correlations can of course also be used in a combined manner in time or space, such as overlap, close proximity and spacing between the intervention segment and the deviation segment. It is therefore conceivable that the control intervention can be different depending on the current local profile deviation itself, or it can be determined based on this how far the intervention segment should be spaced apart from the deviation segment. Of course, the same applies to the positioning and geometrical dimensions of the intervention segment relative to the deviation segment.

[0023] It is also advantageous if, in the method according to the invention, a group of at least two adjacent adjusting mechanisms is adjusted by means of a control intervention in the intervention section. Such grouped adjustment may be accompanied by adjustment directions that are identical or different in quantity and / or quality. In this case, it is obvious that in principle, an adjustment screw between two adjacent adjusting mechanisms can also be omitted. However, the adjacent control of the adjusting mechanisms leads to a better continuous adjustment, so that the advantages of the invention can be further improved, in particular the adjustment fluctuations can be further reduced.

[0024] It is also advantageous that in the method according to the invention the control intervention acts on at least two intervention sections on different sides of the deviation section in the transverse direction. This means that the influence is exerted on both sides, so that the monitoring can be said to surround or sandwich the deviation section on both sides. In this way, undesirable lateral displacement beyond the deviation section can be avoided. For example, if the local profile deviation is a thin spot, the extruded material or molten material is now pressed into the local profile deviation area from both sides of the thin spot by re-adjusting the regulating mechanism on both sides of the thin spot. It is thus ensured that the molten material squeezed into the thin spot from the side will not be squeezed out again on the other side of the thin spot, which may provide undesirable control results there. Therefore, the arrangement on both sides of the deviation section allows better specification of the local results and effects of the control intervention and separation from the undesirable control effect diffusion. Alternatively, a common intervention section can also be arranged between the two deviation sections. That is, in other words, two separate deviation sections can be intervened on both sides thereof using a common intervention section. This can be used in particular to monitor the thickness profile in the two edge portions of the film web. The intervention effect is also symmetrical in particular relative to the production direction of the film web.

[0025] Further advantages are achieved if the control intervention and / or the at least two intervention sections are designed symmetrically or substantially symmetrically in the transverse direction relative to the deviation section in the method according to the invention. Thus, a symmetrical or substantially symmetrical control intervention can also be provided. In this way, the monitoring possibilities and the predictability can be improved. Symmetry can hereby relate on the one hand to the position, geometry and spacing of the control intervention or the intervention sections, but can also relate to the control quality and / or quantity of the control mechanism itself.

[0026] It is also advantageous that in the method according to the invention the deviation segment itself remains free of control intervention. In other words, the deviation segment is designed to be non-controlled or non-adjustable, so that the control result is provided only by the control influence of the adjacent intervention segment. This allows for greater precision and better predictability, since the different control interventions do not overlap or only partially overlap.

[0027] It may also be advantageous if the deviation section has its own control intervention in the method according to the invention. It should also be pointed out here that, within the context of the method, it is of course possible to provide a combination of no control intervention and controlled intervention at different local profile deviations or at different times in the deviation section. Of course, corresponding control interventions can be applied specifically for different deviations on the film web at different times and / or at different locations.

[0028] Another advantage is that in the method according to the invention at least two control interventions are carried out in parallel or at least overlapping in time in two different intervention sections. This temporal overlap allows the different control interventions to be linked to one another, their control results to be compared with one another or a plurality of control interventions to be taken into account for synchronous adjustment. In the case of a plurality of local thickness deviations, this leads to a faster adaptation or a faster improvement of the thickness profile.

[0029] It is also advantageous that in the method according to the invention a prioritization of the required control interventions is carried out in the case of at least two defined local profile deviations. Thus, the locations of the local profile deviations with the greatest risk of damage can be defined so that control interventions are provided most preferentially there. It is also possible that this risk of damage relates to film production stability and / or film product quality. Obviously, the prioritization can also depend on other parameters such as the total thickness of the thickness profile. Thus, for example, in the edge section of a film web, in the case of thick films, an undesirable thick point is assigned a higher risk of damage, while in the case of very thin films, the corresponding thin point has the highest risk of damage.

[0030] It is also advantageous that in the method according to the invention control interventions that were completed earlier are taken into account when generating the control interventions. This makes available the location and / or the results of the control interventions. Thus, the previous effects of the control interventions can be used here and even actively influence undesirable control or regulation fluctuations. In this case, parallel interventions at another location can also be taken into account in terms of time during the generation of the control interventions.

[0031] It is also advantageous if the time course of the thickness profile is taken into account in the method according to the invention when generating the control interventions. Thus, on the one hand, a learning effect can be achieved from previous thickness profile changes and in particular also in conjunction with control interventions that have already been generated, which learning effect can be stored again in a corresponding database. However, it is also possible in particular to take into account the gradient of the thickness profile, i.e. the change in the deviation over time and thus the rate of change. This is advantageous in particular with regard to the prioritization of control interventions or the selection of quality and quantity, so that control interventions can be generated more targeted and more effectively.

[0032] Further advantages are achieved when the time requirement for adjusting the regulating means is taken into account in the method according to the invention when generating the control intervention. Thus, for example, so-called thermocouples are used as regulating means, which are exposed to the effects of temperature and in this way achieve thermal expansion of the regulating means as the temperature increases. This allows the control intervention to be carried out simply and inexpensively, but this results in a time delay before the thermal expansion reaches the desired value. According to the invention, this time requirement can be taken into account when generating the control intervention as a regulation delay or control delay.

[0033] The subject of the invention is also a monitoring device for carrying out a method for monitoring the thickness profile of a film web in the transverse direction by means of a plurality of regulating mechanisms for adjusting the slit opening of an outlet nozzle of a flat film machine. Such a monitoring device has a detection module for detecting the thickness profile and / or detecting the temperature distribution in the transverse direction of the film web transverse to the production direction of the flat film machine to indirectly derive the thickness profile. A comparison module is also provided for comparing at least a portion of the measured thickness profile with a target profile. In addition, the monitoring device has a determination module for determining at least one local profile deviation in a deviation section as a result of the comparison. A generation module is also provided for generating at least one control intervention for adjusting at least one regulating mechanism in an intervention section different from the deviation section. The detection module, the comparison module, the determination module and / or the generation module are preferably designed for carrying out the method according to the invention. Therefore, the monitoring device according to the invention brings the same advantages as those explicitly explained with reference to the method according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Further advantages, features and details of the invention are derived from the following description of embodiments of the invention in detail with reference to the accompanying drawings. The features mentioned in the claims and the description are essential to the invention individually or in any combination, and the accompanying drawings schematically show:

[0035] Figure 1 An embodiment of the monitoring device of the present invention is shown.

[0036] Figure 2 A detailed view showing the outlet nozzle,

[0037] Figure 3 An embodiment showing a thickness profile,

[0038] Figure 4 An embodiment showing a thickness profile in the case of a local profile deviation,

[0039] Figure 5 Shows potential for intervention Figure 4 implementation method,

[0040] Figure 6 shows possible relationships of the intervening segments,

[0041] Figure 7 Another possible relationship of the intervening segments is shown. DETAILED DESCRIPTION

[0042] Figure 1 A possible embodiment of the monitoring device 10 in a flat film machine 100 is shown in a top view. In the top view, the film web FB is fed out of the outlet nozzle 110 in the production direction PR in the form of extruded material. The film web FB now extends along the production direction PR through a large cooling roller and an extended roller system in order to finally be wound on a winding shaft. By means of a corresponding measuring method, here a detection module 20, the thickness profile DP of the film web FB can be monitored directly or indirectly, for example, by means of a temperature profile. It can be provided continuously over the entire width of the film web FB in the transverse direction QR. However, it is also conceivable that the detection module 20 has a movable sensor that moves through the film web FB in a swing from left to right in the transverse direction QR. The information from the detection module 20 is collected in the monitoring device 10 and then processed in the comparison module 30 and the determination module 40. The processing will be explained in more detail later. The corresponding control intervention can now be generated by the generation module 50 and fed back to the flat film machine 100. The control intervention can now act in a displacement manner on the adjusting member 120 , which is designed here as a heat-sensitive pin, in order to achieve a local change in the slit opening 112 of the outlet nozzle 110 there.

[0043] Figure 2 Schematically showing the Figure 1 . Here it can be clearly seen how the adjusting screw 120 can expand thermally due to the exposure to heat. In the case of a support (not shown) mounted on the upper side, this has the result that the pin-shaped bottom side now presses against the upper nozzle lip of the outlet nozzle 110, so that the gap opening 112 is correspondingly reduced. In the opposite direction, that is, when the adjusting screw 120 cools down, the adjusting screw shortens, so that the gap opening 112 is further opened again due to the melt back pressure of the film web FB, and accordingly a greater thickness can be achieved at this section of the film web FB. The detection module 20 is also schematically shown here.

[0044] Figure 3 The configuration solution of the thickness profile DP in the entire transverse direction QR is shown. Through detection by the detection module 20, two edge portions are shown here on the left and right, respectively with a large thick point and a corresponding thin point. The continuous or substantially continuous extension of the thickness profile DP extends between these two edge portions. It can be clearly seen here that the final film product FB is usually completed or available only after the edge portion is cut off. Therefore, different target profiles VP with different threshold ranges can also be provided for different sections.

[0045] Now, Figure 4and Figure 5 The monitoring according to the invention is shown. If a local contour deviation PA is detected at a local position, for example due to exceeding the target contour VP, this section is defined as a deviation section AA. Now, the control intervention can be carried out as follows Figure 5 As shown, an intervention section EA is defined on the left and right of the deviation section AA. This is the thick point in the deviation section AA that is to be reduced. The desired change in the thickness profile DP is indicated here by means of arrows, wherein the initial design of the thickness profile DP is Figure 5 , which is still shown in dashed lines. To achieve this effect, the control intervention can now move the adjustment mechanism 120 upwards in different amounts but of the same quality in the intervention sections EA adjacent on both sides, so that space is correspondingly provided to redistribute the molten material from the deviation section AA into the adjacent intervention sections EA. As a result of the control, the thickness profile DP is thus flattened in the desired manner. For the deviation in the edge section of the film web FB, the arrangement can also be exactly the opposite, so that the common intervention section EA is located between the two deviation sections AA, in particular in the edge section of the film web FB.

[0046] Figure 6 and Figure 7 Different relationships are shown in a local manner. Figure 6 The intervention section EA can, for example, directly or substantially directly adjoin the deviation section AA laterally. However, it is also conceivable that, according to Figure 7 , a corresponding spacing in the form of a safety distance is provided between the deviation section AA and the intervention section EA. In addition, Figure 7 It is shown that two intervention sections EA are arranged on both sides, which are even designed in a symmetrical manner here.

[0047] The above description of the embodiments describes the invention only within the scope of examples. It is obvious that the individual features of the embodiments can be freely combined with one another without departing from the scope of the present invention.

[0048] Reference numerals list

[0049] 10 Monitoring device

[0050] 20 detection modules

[0051] 30 Comparison modules

[0052] 40 Determine the module

[0053] 50Generate Modules

[0054] 100 flat film machine

[0055] 110 outlet nozzle

[0056] 112 Gap opening

[0057] 120 adjustment mechanism

[0058] FB film web

[0059] DP Thickness Profile

[0060] VP Target Profile

[0061] PA local contour deviation

[0062] AA deviation section

[0063] EA Intervention Segment

[0064] QR Horizontal

[0065] PR production direction

Claims

1. A method for monitoring the thickness profile (DP) of a film web (FB) in the transverse direction (QR) by means of a plurality of adjustment mechanisms (120) for adjusting the slot opening (112) of an outlet nozzle (110) of a flat film machine (100), comprising the following steps: - detecting the thickness distribution (DP) in the transverse direction (QR) of the film web (FB) transverse to the production direction (PR) of the flat film machine (100), - comparing at least a portion of the measured thickness profile (DP) with a target profile (VP), - as a result of the comparison, at least one local contour deviation (PA) is determined within the deviation section (AA), - generating at least one control intervention for adjusting at least one of the adjustment mechanisms (120) within an intervention section (EA) different from the deviation section (AA), in particular to avoid or reduce profile deviations and thereby avoid the formation of piston rings or undesired thick and / or thin spots in the edge portion of the film web.

2. The method according to claim 1, characterized in that The intervention section (EA) has a different, in particular a greater, extension in the transverse direction (QR) than the deviation section (AA).

3. The method according to any one of the preceding claims, characterized in that At least two of the adjusting elements (120) are adjusted by the control intervention within the intervention section (EA), in particular by different adjustment amounts.

4. The method according to any one of the preceding claims, characterized in that The intervention section (EA) overlaps the deviation section (AA) in the transverse direction (QR) of the film web (FB).

5. The method according to any one of the preceding claims, characterized in that The intervention section (EA) is immediately adjacent or substantially immediately adjacent to the deviation section (AA) in the cross direction (QR) of the film web (FB).

6. The method according to any one of the preceding claims, characterized in that The intervention section (EA) is spaced apart from the deviation section (AA) in the transverse direction (QR) of the film web (FB).

7. The method according to any one of the preceding claims, characterized in that A group of at least two adjacent adjusting elements (120) are adjusted within the intervention section (EA) by means of the control intervention.

8. The method according to any one of the preceding claims, characterized in that The control intervention acts in the transverse direction (QR) on at least two intervention sections (EA) on different sides of the deviation section (AA), or the control intervention acts in the transverse direction (QR) on a common intervention section (EA) between two deviation sections (AA).

9. The method according to claim 8, characterized in that The control intervention and / or the at least two intervention sections (EA) are designed symmetrically or substantially symmetrically in the transverse direction (QR) with respect to the deviation section (AA), or the two deviation sections (AA) are designed symmetrically around a common intervention section (EA).

10. The method according to any one of the preceding claims, characterized in that The deviation section (AA) itself has no control intervention.

11. The method according to any one of the preceding claims, characterized in that The deviation section (AA) itself has a control intervention.

12. The method according to any one of the preceding claims, characterized in that At least two control interventions at two different intervention sections (EA) take place in parallel in time or at least overlapping in time.

13. The method according to any one of the preceding claims, characterized in that When there are at least two defined local contour deviations (PA), the required control interventions are prioritized.

14. The method according to any one of the preceding claims, characterized in that Control interventions completed earlier are taken into account when generating the control intervention.

15. The method according to any one of the preceding claims, characterized in that The time curve of the thickness profile (DP) is taken into account when generating the control intervention.

16. The method according to any one of the preceding claims, characterized in that When generating the control intervention, the time required for adjusting the adjusting device (120) is taken into account.

17. A monitoring device (10) for executing a method for monitoring a thickness profile (DP) of a film web (FB) in a transverse direction (QR) by means of a plurality of adjustment mechanisms (120) for adjusting a slit opening (112) of an outlet nozzle (110) of a flat film machine (100), the monitoring device (10) comprising: a detection module (20) for detecting a thickness profile (DP) of the film web (FB) in a transverse direction (QR) transverse to a production direction (PR) of the flat film machine (100); a detection module (20) for transmitting at least one of the measured thickness profiles (DP) to the film web (FB); A comparison module (30) for comparing a portion of the film web with a target profile (VP); a determination module (40) for determining at least one local profile deviation (PA) within a deviation section (AA) as a result of the comparison, and also a generation module (50) for generating at least one control intervention for adjusting at least one of the adjustment mechanisms (120) within an intervention section (EA) different from the deviation section (AA), in particular to avoid or reduce profile deviations, thereby avoiding the formation of piston rings or undesirable thick and / or thin spots in the edge portions of the film web.

18. The monitoring device (10) according to claim 17, characterized in that The detection module (20), the comparison module (30), the determination module (40) and / or the generation module (50) are designed to carry out a method having the features of one of claims 1 to 17.

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