METHOD FOR AUTOMATED CONTROL OF THE SIZE OF A GAP IN A NOZZLE ARRANGEMENT AND CONTROL AND / OR REGULATION SYSTEM

Description

[0001] The present invention relates to a method for the automated control of the size of a gap in a nozzle arrangement. The invention further relates to a control and / or regulation system.

[0002] In flat film applications, such as the production of films or tapes made of thermoplastic materials, state-of-the-art automatic dies are used to form an extruded plastic melt into a thin rectangular sheet or film. These automatic dies have a first and a second die lip, as well as a die exit gap located between the die lips for controlled adjustment of the thickness profile of the conveyed melt. A plurality of actuators, each coupled to a thermocouple, are arranged on the first die lip. When heated, the thermocouples expand and exert mechanical pressure on the die lip via the associated actuator, causing it to deform at the corresponding point. In particular, this reduces the size of the die exit gap.Furthermore, the thermocouples can compress upon cooling, and via the actuators, this exerts a mechanical pull on the nozzle lip, thereby increasing the nozzle exit gap at the corresponding point. The thermocouples can be controlled by a nozzle control system such that the gap adjustment is achieved by the expansion or contraction of the thermocouples through a mechanical force applied by the respective actuator to the first nozzle lip.

[0003] It is important that the controlled thickness profile of the melt can be achieved by adjusting the nozzle exit gap. The thickness profile is crucial for subsequent processes such as winding film webs for storage or further processing the film into bags. Thickness gauges, particularly those using ultrasonic or infrared measurements, are used to monitor the thickness profile. These gauges continuously minimize deviations in the cross-profile within a net area of ​​the film or melt to prevent so-called piston rings on the film roll. In other words, deviations from a target film profile are continuously detected via thickness measurement, and a setpoint is generated for the individual thermocouples or actuators on the nozzle lip. This allows the nozzle exit gap to be locally increased or decreased to achieve a uniform thickness.As a measurable and displayed quality criterion for a flat film produced using a nozzle control system, a statistical 2 or 3 sigma deviation of the measured film thickness from a mean value or a target value is usually specified.

[0004] The proper functioning of nozzle control systems requires precise, manual adjustment of a homogeneous nozzle outlet gap adapted to the product being manufactured. Consequently, before commissioning and, if necessary, during nozzle control, the operator must also adjust individual actuators of the nozzle assembly to ensure a stable process.

[0005] The process of adjusting the nozzle exit gap is often carried out manually during a production break, by the operator manually closing or opening individual actuators. This adjustment of individual actuators can be very time-consuming.

[0006] Due to the mutual, and especially asymmetrical, influence of the adjusting elements on the bending curve of the nozzle lip (lateral influence), even after manual centering of the nozzle exit gap, an adverse profile tolerance with a 2-sigma deviation of the thickness profile of more than 20-40% can occur. The manual centering of the nozzle exit gap is significantly dependent on the operator's professional experience. Furthermore, manual centering is time-consuming and sometimes not fully reproducible, and the individual adjusting elements must be repeatedly set or readjusted sequentially with each subsequent commissioning or with each further deviation from the target value of the thickness profile during production.

[0007] Furthermore, the film edge in flat film extrusion is disadvantageously characterized by the so-called neck-in, which is due to the melt being drawn out of the die assembly and the viscoelastic behavior of the melt. As a result of the neck-in, there is a reduction in the film width relative to the width of the die exit gap, as well as a corresponding thickening of the film edge area. This thickening is usually removed by edge trimming before winding and represents the net film area. In the prior art, known die control systems are largely limited to the net film area. However, significant material losses can occur due to edge trimming.

[0008] While it is possible to directly recirculate the edge trim back to an extruder to supply the melt, experience has shown that, with commonly used settings of the control elements in the edge region, the recirculated edge trim can vary significantly due to the resulting edge thickness, potentially leading to unstable conveying behavior. Such instability results in fluctuations in throughput and, consequently, a detrimental effect on the desired thickness profile of the melt.

[0009] Known fonts used in foil production are EP 1 964 659 A1, EP 2 865 511 A1, EP 2 837 484 A1, DE 198 55 751 A1 and EP 0 257 233 A2.

[0010] It is therefore an object of the present invention to at least partially overcome the disadvantages described above. In particular, it is an object of the present invention to provide an adjustment of the nozzle exit gap in the edge region of the film with improved precision, thereby enabling targeted adjustment of the edge region.

[0011] The foregoing problem is solved by a method having the features of claim 1. Furthermore, the problem is solved by a control and / or regulation system having the features of claim 14. Further features and details of the invention will become apparent from the dependent claims, the description, and the drawings. Features and details described in connection with the method according to the invention naturally also apply in connection with the control and / or regulation system according to the invention, and vice versa, so that the disclosure relating to the individual aspects of the invention always makes, or can make, reciprocal references.

[0012] Within the scope of the application, the term "control" preferably encompasses control and / or regulation methods and / or machine learning methods to which a measured value relating to the thickness profile and / or the characteristic properties of the melt can be supplied as an input signal, and based on this, an adjustment of individual or all actuators or thermocouples can be performed. The adjustment is carried out by means of a control value or control signal generated by the control system for the individual actuators or the associated thermocouples.

[0013] Furthermore, within the scope of the application, the term "pinning" specifically encompasses the adhesion or fixation of the molten metal to a casting roller. This adhesion can preferably be achieved electrostatically or pneumatically.

[0014] For the purposes of this application, actuating elements include, by way of example, elements for the local adjustment of the nozzle exit gap, such as thermo-expansion bolts, stepper / servo motors, or piezo actuators. Furthermore, actuating elements that are generally piezomechanical or operated by electrochemical volume changes are also conceivable.

[0015] According to a first aspect of the invention, the problem is solved by a method for the automated control of the size of a nozzle outlet gap of a nozzle assembly, wherein the nozzle assembly has a first and a second nozzle lip and a nozzle outlet gap arranged between the nozzle lips for the controlled adjustment of a thickness profile of a conveyable melt. A plurality of actuating elements, in particular a plurality of actuating bolts, are arranged on the first nozzle lip, which are coupled to an associated thermocouple, wherein the thermocouples can be controlled by the control system in such a way that the gap adjustment can be achieved by means of a mechanical force acting from the respective actuating element on the first nozzle lip by means of an expansion or contraction of the thermocouples.The actuators are automatically adjusted based on measurement signals from at least one sensor. The sensor is designed and / or positioned on the nozzle assembly in such a way that the thickness profile of the melt can be determined. The right and left edges of the melt are monitored by the sensor and controlled or regulated in such a way that the respective edge area is adjusted by modifying the actuators depending on the material, in particular viscosity and / or viscoelasticity, quality criteria, and a conveying speed.

[0016] The invention has the advantage that the edge region of the melt or film, located outside the net area, is explicitly considered and evaluated. By monitoring the edge region of the melt, the entire thickness profile can be optimally adjusted. Therefore, the entire width of the nozzle exit gap can be advantageously utilized. The edge region can be evaluated with regard to quality and / or stability criteria, particularly depending on the product to be manufactured and / or the production process. Furthermore, it is advantageous that by monitoring the edge region and adjusting the control elements accordingly, the edge region can be set in such a way as to reduce edge trimming. The melt material can therefore be utilized optimally.

[0017] The at least one sensor is preferably connected to the control system via data communication for transmitting measurement signals. For example, the sensor can be configured as a temperature sensor, infrared or ultrasonic sensor, or as an optical sensor. By way of example, the sensor can be configured as a camera for optical image acquisition of the melt, particularly the edge region. The sensor can preferably be arranged on a casting roller to measure the temperature of the melt exiting the die gap and conveyed along the casting roller. Furthermore, the sensor can measure the flow behavior of the melt, particularly at the edge. In particular, several sensors can be provided for precise measurement of the entire thickness profile and especially the edge region, and / or differently configured sensors can be combined.By comparing the measured thickness profile with a target value, the control system can generate a base setpoint for the individual actuators, ensuring a maximum deviation from the target value of 30%, particularly 10%, and preferably in the range of 2% to 5%. The control system also includes a data processing unit configured to process the sensor's measurement signals and generate a control signal for the actuators or the associated thermocouples for adjusting the nozzle exit gap. In other words, processing the sensor's measurement signals results in the control or regulation of individual, multiple, or all actuators of the nozzle assembly. Consequently, an optimized melt flow distribution for process stability and product quality, and the resulting shape of the melt plume and / or film edge, is achieved.

[0018] The invention further has the advantage that the design of the melt flow distribution at the nozzle exit gap, particularly in the edge region (and consequently the resulting stability there), is determined, for example, as a function of an operating point (e.g., a discharge rate or a temperature of the melt) and a formulation (e.g., viscosity or viscoelasticity). For example, at high discharge rates and / or high melt viscosity, increased upward deflection of the nozzle exit gap can occur in a central region. This, in turn, can result in reduced melt flow in the edge regions. The nozzle control can advantageously compensate for this and make corresponding adjustments to the actuators so that the film edge meets the defined stability criteria. Furthermore, with very thin films, it can be advantageous to create a stable, thicker edge area to ensure process stability even at high line speeds. Conversely, with thick films, the film edge can be made thinner to achieve higher speeds due to its slower cooling.By controlling the nozzle and adjusting the edge areas, the design of the film edges is therefore known, reproducible, and, in particular, symmetrical. Accordingly, this control enables high process stability and product quality.

[0019] Preferably, individual actuating elements are adjusted with a time delay. This has the advantage that a product-specific and characteristic formation of the melt plume can be achieved.

[0020] In a preferred embodiment, the actuating elements, in particular all actuating elements, can be adjusted simultaneously. This simultaneous, and especially automatic, adjustment of the actuating elements eliminates the need for time-consuming manual adjustment of individual actuating elements sequentially, thus saving the operator numerous iterations. This significantly accelerates the entire production process. Furthermore, simultaneous adjustment of the actuating elements, particularly all of them, reduces cross-interference between the actuating elements. Another significant advantage over selective and usually manual adjustment of the actuating elements is the symmetry of the melt edges or film edges achievable through simultaneous adjustment.This symmetry of the neck-in behavior in turn enables higher process stability and product quality, especially with regard to consistency across the entire film width.

[0021] Within the scope of the invention, it is further conceivable that the actuating elements, in particular all actuating elements, are adjusted via the same stroke, thereby enabling parallel adjustment. In particular, all actuating elements can preferably be adjusted symmetrically, thereby allowing a standardized nozzle outlet gap of the nozzle arrangement to be set.

[0022] The standardized nozzle exit gap ensures high reproducibility, thus guaranteeing consistent product quality with every subsequent commissioning. The standardized nozzle exit gap can be adjusted, for example, depending on the melt or material of the product being manufactured. The adjustment of the actuators can be achieved, for example, by standardizing the torque setting of the actuator, resulting in the actuators exerting the same or substantially the same contact pressure on the first nozzle lip.

[0023] In a preferred embodiment, it is provided that, particularly when a control limit is reached, one or more actuators are adjusted simultaneously. The control limit can represent a maximum or minimum opening of the nozzle outlet gap. This advantageously allows for the fastest possible response to excessive opening or closing of the nozzle outlet gap by adjusting the actuators.

[0024] Preferably, it is conceivable that edge adhesion of the melt exiting the nozzle assembly to a casting roller is achieved using electrostatics and / or air, wherein the edge adhesion, in particular the strength of the edge adhesion and / or the position on the casting roller, is adjusted by means of a control system depending on the material and / or quality criteria and / or the conveying speed. Edge adhesion describes the adhesion of the melt exiting the nozzle gap to the casting roller, for example via electrostatics ("electrostatic pinning") and / or via air ("air pinning"). In particular, electrostatic pinning between an edge thickening and the net area of ​​the film can cause a thin spot to occur, since the electrostatics attract melt particles from both sides.The extent of the thin spot depends, for example, on the melt flow distribution at the nozzle exit gap, the viscoelastic behavior of the melt, and process settings such as line speed, melt plume length, pinning strength, and other application devices like vacuum boxes or air knives. By adjusting the edge adhesion or pinning, the reproducibility of the melt flow distribution at the nozzle exit, particularly in the nozzle's edge regions, and / or the creation of symmetry can be achieved. A particular advantage of nozzle control is the reproducible design of the film edge, unlike in the prior art, which allows for significantly simpler and reproducible pinning adjustment. The nozzle control can also provide setting instructions or specifications for pinning position and strength.

[0025] Furthermore, it is advantageously provided that the edge adhesion is continuously monitored and / or recorded during operation of the nozzle assembly. This has the advantage that the result of the pinning adjustment is recorded reproducibly and can be optimized according to predefined quality criteria.

[0026] Alternatively or additionally, edge adhesion can be detected using a multi-dimensional motorized movement and / or an optical system and / or temperature measurement of the melt on the casting roller and / or sensors to determine the thickness profile of the melt. The detection of the pinning position or the position of the edge adhesion can be achieved, for example, using 1-, 2-, or 3-dimensional (motorized) movement or optical systems. The detection of the pinning result (e.g., the shape of the edge area) can be achieved by measuring the temperature of the melt on the casting roller and / or by using conventional thickness measurement systems that measure the entire film width and provide the most precise information possible about the shape of the edge.The pinning result (shape of the edge area) can be captured, for example, using a traversing sensor, particularly an infrared sensor or an FPM sensor, below the point of contact with the casting roller and / or using conventional thickness measurement systems. Suitable quality criteria for edge stability include, for example, the position of the thin spot, the ratio of thin to thick spot, the shape and / or form of the thin and thick spots, the measured temperature profile in the edge area, and the measured film thickness profile in the edge area. In addition to the control signals for the actuators, the nozzle control system can also generate the necessary information for setting and / or controlling electrostatic and pneumatic pinning. This contributes significantly to the previously described increase in process stability.

[0027] Within the scope of the invention, it is further conceivable that the specific setting of the actuating elements, depending on the material, in particular viscosity and / or viscoelasticity, and / or quality criteria and / or the conveying speed, is stored for recommissioning of the nozzle assembly and / or integrated as a self-learning algorithm. This has the advantage that targeted commissioning with pre-stored settings is enabled for subsequent film production, thereby further increasing the reproducibility of the nozzle exit gap setting. In particular, the backlash-free setting can be stored as a recipe value and / or automatically controlled with respect to specific predefined criteria and / or implemented as a self-learning algorithm.

[0028] Preferably, it can be provided that, during the initial commissioning of the nozzle assembly for conveying the melt, the actuators for subsequent gap size control are set to zero backlash as the initial setting. This has the advantage that the zero backlash setting of the actuators enables precise adjustment of the nozzle exit gap. If there were excessive play in the actuators, the heating or cooling of the thermocouples might not result in a partial deformation of the nozzle lip, but rather the change in length of the thermocouples would be partially lost to the play in the nozzle assembly. Furthermore, the zero backlash setting of the actuators during commissioning of the nozzle assembly ensures a reproducible starting point for the nozzle control.This generally increases process stability, for example, by advantageously increasing line speed when conveying the melt through the nozzle assembly, or by significantly improving the efficiency of a flat film line. The reproducible, backlash-free adjustment also enables increased quality consistency across different products, resulting in improved outcomes for both new and retrofitted machines. In particular, the backlash-free adjustment can be performed automatically during the commissioning of the nozzle assembly, eliminating any manual operator intervention. This ensures high reproducibility during the initial nozzle assembly setup and / or during production. It also simplifies machine setup in general and significantly reduces the setup time for the nozzle assembly before production.Likewise, the need for further manual adjustments by the operator during production to control the thickness profile can be reduced.

[0029] Preferably, at least two actuators can be adjusted simultaneously. This has the advantage that the simultaneous, and especially automatic, adjustment of at least two actuators eliminates the need for time-consuming manual adjustment of individual actuators sequentially, thus saving the operator numerous iterations. This significantly accelerates the entire production process. Furthermore, the simultaneous adjustment of two actuators, particularly two adjacent actuators, reduces cross-interference between them.

[0030] Furthermore, it can advantageously be provided that at least one clamping blade is arranged in each of the right- and left-hand edge regions of the nozzle arrangement, whereby the width of the nozzle exit gap can be variably adjusted, wherein the method for adjusting the width of the nozzle exit gap and for clamping the adjusting elements can be carried out automatically and comprises the following steps: Unclamping the clamping blade within the nozzle exit gap; moving the clamping blade within the nozzle exit gap; clamping the clamping blade within the nozzle exit gap to fix individual actuating elements.

[0031] This has the advantage that the automatic adjustment of the clamping blades for the width of the nozzle exit gap results in significant time savings in the production process, as no manual adjustment by the operator is required. Furthermore, the nozzle control provides the basis for another customer benefit: fully automatic width adjustment on a flat film line. This allows for a highly flexible flat film format. By automating the clamping blade adjustment process, higher sales volumes can be achieved, and the operator of the nozzle assembly is relieved of physical and mental strain. Automation also increases the precision of the clamping blade adjustment.

[0032] Preferably, a standardized nozzle exit gap of the nozzle assembly is set by means of backlash-free adjustment of the adjusting elements. The adjusting elements can be adjusted symmetrically. The standardized nozzle exit gap ensures high reproducibility, thus guaranteeing consistent product quality with each subsequent commissioning. The setting of the standardized nozzle exit gap can, for example, be adjusted depending on the melt or material of the product being manufactured. Furthermore, the standardized setting reduces the setup time of the nozzle assembly for production.

[0033] In a preferred embodiment, the degree of backlash of the actuating elements can be adjusted depending on the type of melt and / or the size of a basic gap in the nozzle arrangement. In particular, the material of the melt, the operating temperature or melt temperature, or the melt formulation, especially its viscosity and / or viscoelasticity, can be taken into account. The degree of backlash can also preferably be adjusted with regard to quality and / or stability criteria of the melt and / or the production process, such as the line speed and / or the length of the melt plume.

[0034] Within the scope of the invention, it is further conceivable that the backlash-free adjustment of the actuating elements is achieved by means of a standardized setting of the actuating element's torque, whereby the actuating elements exert the same or substantially the same contact pressure on the first nozzle lip. In particular, the standardized setting of the actuating elements' torque can be 2 Nm. This has the advantage that no manual adjustment of a mechanical nozzle outlet gap, adapted to the product being manufactured, is required for control. The actuating elements of the nozzle assembly are only adjusted once during commissioning or recommissioning of the nozzle assembly so that all actuating elements exert a substantially the same low pressure on the nozzle lip. In other words, the actuating elements thus cause the same slight deformation of the nozzle lip or a slight enlargement or reduction of the nozzle outlet gap.

[0035] In a preferred embodiment, the actuators are initially set to the maximum opening stroke of the nozzle assembly. This has the advantage that specific centering of the nozzle outlet gap is unnecessary when the maximum opening stroke of the nozzle assembly is used as the starting point for control. This results in time savings in production. Furthermore, it is not necessary for the operator to adjust individual actuators to achieve a uniform film thickness distribution to a 2-sigma tolerance of, for example, 10%, which is required for commissioning the nozzle control. The nozzle control according to the invention can also achieve a controlled tolerance of approximately 10% during production, even starting from an uncontrolled tolerance of over 20%, particularly over 30% or 40%, during commissioning.In particular, it is advantageously possible to make the start-up and production of the nozzle arrangement reproducible, since the adjustment or setting of all actuating elements is known at any time using the nozzle control.

[0036] Preferably, the backlash-free setting of the actuators can be saved for recommissioning of the nozzle assembly and / or integrated as a self-learning algorithm. This has the advantage that targeted commissioning with pre-stored settings is enabled for subsequent film production, further increasing the reproducibility of the nozzle exit gap setting. In particular, the backlash-free setting can be stored as a recipe value and / or automatically controlled with respect to specific predefined criteria and / or implemented as a self-learning algorithm.

[0037] In a further preferred embodiment of the invention, it is conceivable that, following the initial setting, the actuating elements along the entire width of the nozzle assembly are automatically controlled to adjust the gap, particularly in an edge region of the nozzle assembly. After the initial setup of the nozzle assembly according to the embodiments described above, the nozzle control automatically adjusts the nozzle exit gap suitable for the product. Advantageously, the control is performed along the entire width of the nozzle exit gap. Since this also includes adjusting the actuating elements in the right and left edge regions of the nozzle exit gap, it is not necessary for the operator to iteratively achieve a stable film edge during production by manually adjusting them.The control system can exert a targeted influence on the melt flow distribution during commissioning and production, particularly in the edge region of the nozzle assembly, thus achieving a stable melt edge without user intervention. In other words, the thickness profile is also controlled outside the net area of ​​the film.

[0038] Within the scope of the invention, it is further conceivable that the adjusting elements can be adjusted depending on the type of melt and / or the size of a basic gap in the nozzle assembly. In particular, the material of the melt, the operating temperature or melt temperature, or the melt formulation, especially its viscosity and / or viscoelasticity, can be taken into account. This has the advantage that the nozzle exit gap can be set very precisely for each material. The adjustment can also preferably be made with regard to quality and / or stability criteria of the melt and / or the production process, such as the line speed and / or the length of the melt plume.

[0039] Preferably, the clamping blade can be thermally released and / or locked. In particular, the clamping blade can be released and / or locked by means of a suitable thermocouple coupled to the clamping blade. The thermocouples expand when heated and thereby exert mechanical pressure on the associated clamping blade. For example, the thermocouples can be controlled by the system such that the clamping blade is released and / or locked by expansion or contraction of the thermocouples. Thermal release and / or locking allows for precise fine-tuning. This enables exact positioning and / or contact pressure adjustment of the clamping blades and therefore ensures improved and automated clamping blade adjustment.

[0040] In a preferred embodiment, it can be provided that when the clamping blade is moved to reduce the nozzle exit gap, a specific, and in particular pre-stored, setting of the actuating elements, especially in an edge region, is transferred to the reduced nozzle exit gap. This has the advantage that targeted commissioning with pre-stored settings is possible during subsequent film production, thereby further increasing the reproducibility of the nozzle exit gap setting. In particular, the setting of the actuating elements can be stored as a recipe value and / or automatically controlled with respect to specific predefined criteria. By transferring the setting of the actuating elements when the width of the nozzle exit gap is changed, optimal adaptation to the new width can be achieved.Additionally, transferring the settings, scaled to the width of the nozzle exit gap, results in further time savings in production.

[0041] Within the scope of the invention, it is further conceivable that, prior to moving the clamping blade, a check is performed to determine whether an adjustment of the specific, particularly pre-stored, setting of the actuating elements is necessary, especially in a peripheral area. This check can be performed depending on the melt or the material of the product to be manufactured. In particular, the material of the melt, the operating temperature or melt temperature, or the melt formulation, especially its viscosity and / or viscoelasticity, can be taken into account. The check can also preferably be configured with regard to quality and / or stability criteria of the melt and / or the process, such as the line speed and / or the length of the melt plume.Advantageously, specific edge settings can be transferred to the new edge section to the inside, and an automatic format adjustment of the nozzle exit gap can be performed.

[0042] Alternatively or additionally, it is conceivable that when the clamping blade is moved to reduce the nozzle exit gap, a specific, particularly pre-stored, setting for edge adhesion of the melt exiting the nozzle assembly to a casting roller is transferred to the reduced nozzle exit gap by means of electrostatics and / or air. Furthermore, by transferring the edge adhesion setting when the width of the nozzle exit gap is adjusted, optimal adaptation to the new width can be further improved.

[0043] Preferably, the fixed actuators can be excluded from the control system when the clamping blade is moved and locked to reduce the nozzle exit gap. In a preferred embodiment, the fixed actuators can be set to a precise setpoint by the control system. This has the advantage that the setpoint for the actuators fixed by the clamping blade can be set to a defined value, in particular a maximum or minimum opening stroke, so that the fixed actuators do not change their position. This ensures a tight seal of the nozzle assembly, since the fixed actuators preferably do not allow any melt to pass through the nozzle exit gap. Thus, it can be ensured that no melt escapes outside the intended edge region of the nozzle exit gap.

[0044] In a preferred embodiment, the control of the actuators for adjusting the nozzle exit width can be based on stored and / or historical profiles. This has the advantage that, in the case of subsequent film production, targeted commissioning and production with pre-stored settings are possible, thereby further increasing the reproducibility of the nozzle exit gap setting. Furthermore, it is advantageously possible to derive quantitative and / or qualitative learning steps from the history for adjusting the nozzle exit width.

[0045] Advantageously, the displacement of the clamping blade can be limited to a maximum adjustment torque. This provides protection against damage and / or incorrect adjustment of the clamping blade. The displacement limit can be selected based on the material, particularly its viscosity and / or viscoelasticity, and / or quality criteria, and / or the conveying speed of the nozzle assembly. This allows for optimal adjustment for the production process.

[0046] Alternatively or additionally, it is conceivable that the clamping blade's movement could be motorized. This would eliminate the need for manual operator intervention. Furthermore, motorized movement of the clamping blade would particularly facilitate the full automation of the nozzle arrangement.

[0047] According to a further aspect of the invention, a control and / or regulation system with a control unit for carrying out the method according to one of the preceding embodiments is provided. Features and details described in connection with the method according to the invention naturally also apply in connection with the control and / or regulation system according to the invention, and vice versa, so that the disclosure relating to the individual aspects of the invention always refers to each other.

[0048] The invention is explained in more detail below with reference to non-limiting embodiments illustrated in the figures. These show Fig. 1 a schematic view of a nozzle arrangement according to the invention according to a first embodiment; Fig. 2 a schematic view of a nozzle arrangement according to the invention according to a further embodiment with a characteristic thickness profile; Fig. 3 each a schematic diagram of a control system according to the invention with simultaneous and parallel adjustment of the actuating elements; Fig. 4 each a schematic diagram of a control system according to the invention for transmitting the setting of the actuating elements in a boundary region.

[0049] For the sake of clarity, similar elements in the following figures are marked with the same reference symbols.

[0050] Fig. 1Figure 1 shows a schematic view of a nozzle arrangement 10 according to the invention for the automated control of the size of a nozzle outlet gap according to a first embodiment. The nozzle arrangement 10 has a first nozzle lip 12 and a second nozzle lip 14. A nozzle outlet gap 16 is arranged between the nozzle lips 12 and 14 for the controlled adjustment of a thickness profile of a conveyable melt. The melt, for example, a plastic melt for the production of a flat film, is conveyed through the nozzle outlet gap 16. Depending on the size or height of the nozzle outlet gap 16, the thickness of the melt is adjusted or changed.

[0051] To adjust the size or height of the nozzle outlet gap 16, a plurality of actuating elements 20, in particular approximately 120 actuating elements 20, are arranged on the first nozzle lip 12. This is symbolically represented in Fig. 1 Only one actuator 20 is shown.

[0052] The actuating element 20 is exemplified as an actuating bolt which has a tapered shape in the direction of the first nozzle lip 12. The tapered shape leads to a point-like tip. The point-like tip forms a minimal contact area between the actuating element 20 and the first nozzle lip 12. In other words, the actuating element 20 is connected to the first nozzle lip 12 via the point-like tip.

[0053] The actuator 20 is coupled to an associated thermocouple 30. When heated, the thermocouple 30 expands and exerts mechanical pressure on the first nozzle lip 12 via the actuator 20, causing it to deform at the corresponding location. Specifically, this reduces the nozzle outlet gap 16. Furthermore, when cooling, the thermocouple 30 can compress and, via the actuator 20, exerts mechanical tension on the first nozzle lip 12, thereby increasing the nozzle outlet gap 16 at the corresponding location. The thermocouple 30 can be controlled by a nozzle control such that the gap adjustment can be achieved by the actuator 20 applying a mechanical force to the first nozzle lip 12 through expansion or contraction of the thermocouple 30.In other words, the thermocouple 30 can exert pressure on the first nozzle lip 12 by means of an exemplary expansion via the actuating element 20. The design of the actuating element 20 with its tapered shape leads in particular to a very precise adjustment of the nozzle outlet gap 16, since the effect on adjacent actuating elements is reduced. The nozzle outlet gap 16 is therefore deformed within a limited spatial area of ​​the first nozzle lip 12. The thermocouple 30 can, for example, be connected to a heating or cooling device, which is controlled by the control system to heat or cool the thermocouple 30.

[0054] Furthermore, the adjusting elements 20 can be automatically adjusted based on measurement signals from a sensor (not shown). The sensor is designed and / or arranged on the nozzle assembly 10 such that conclusions can be drawn about the thickness profile of the melt. The right and left edge regions of the melt are monitored by the sensor and controlled or regulated in such a way that the respective edge region is adjusted by adjusting the adjusting elements 20 depending on the material, in particular viscosity and / or viscoelasticity, and / or quality criteria and / or a conveying speed. This has the advantage that the edge region of the melt or film located outside the net area is explicitly considered and evaluated. By monitoring the edge region of the melt, the entire thickness profile can be optimally adjusted.The marginal area can be evaluated with regard to quality and / or stability criteria, particularly depending on the product to be produced and / or the production process.

[0055] When commissioning the nozzle assembly 10 for conveying the melt, the actuators 20 for subsequent control of the nozzle outlet gap 16 can be set to zero backlash as a one-time initial setting. This has the advantage of enabling precise adjustment of the nozzle outlet gap 16. If there were excessive play in the actuators 20, the heating or cooling of the thermocouples 30 might not fully deform the nozzle lip 12. Furthermore, setting the actuators 20 to zero backlash during commissioning of the nozzle assembly 10 ensures a reproducible starting point for the nozzle control. This generally increases process stability. In particular, the zero-backlash setting during commissioning of the nozzle assembly 10 can be performed automatically, thus eliminating any manual intervention by an operator.

[0056] For example, at least two actuators 20 can be adjusted simultaneously. This has the advantage that the simultaneous, and especially automatic, adjustment of at least two actuators 20 eliminates the need for time-consuming manual adjustment of individual actuators one after the other. Likewise, the simultaneous adjustment of two actuators 20, especially two adjacent actuators 20, reduces cross-interference between the actuators 20.

[0057] Furthermore, at least one clamping blade (not shown) can be arranged in a right-hand and left-hand edge region of the nozzle arrangement 10, whereby the width of the nozzle exit gap 16 can be variably adjusted, wherein a method for adjusting the width of the nozzle exit gap 16 and for clamping the adjusting elements 20 can be carried out automatically and comprises the following steps: Unclamping the clamping blade within the nozzle outlet gap 16; moving the clamping blade within the nozzle outlet gap 16; clamping the clamping blade within the nozzle outlet gap 16 to fix individual actuating elements 20.

[0058] This has the advantage that by automatically adjusting the clamping blades for width adjustment of the nozzle exit gap 16, a significant time saving can be achieved in the production process, as no manual adjustment by the operator is required.

[0059] Fig. 2Figure 10 shows a schematic view of a nozzle arrangement according to the invention for the automated control of the size of a nozzle exit gap, according to a further embodiment with a characteristic thickness profile. The nozzle arrangement 10 has a first nozzle lip 12 (not shown) and a second nozzle lip 14 (not shown). A nozzle exit gap 16 is arranged between the nozzle lips 12 and 14 for the controlled adjustment of a thickness profile of a conveyable melt 50. The melt 50, for example, a plastic melt for the production of a flat film, is conveyed through the nozzle exit gap 16. Depending on the size or height of the nozzle exit gap 16, the thickness of the melt 50 is adjusted or changed.

[0060] To adjust the size or height of the nozzle outlet gap 16, a plurality of actuating elements 20, in particular approximately 120 actuating elements 20, are arranged on the first nozzle lip 12. Each actuating element 20 is coupled to an associated thermocouple 30. When heated, the thermocouple 30 expands and exerts mechanical pressure on the first nozzle lip 12 via the associated actuating element 20, causing it to deform at the corresponding location. In particular, this reduces the size of the nozzle outlet gap 16. Furthermore, when cooling, the thermocouple 30 can compress and, via the actuating element 20, exerts mechanical tension on the first nozzle lip 12, thereby increasing the size of the nozzle outlet gap 16 at the corresponding location.The thermocouple 30 can be controlled by a nozzle control such that the gap adjustment can be achieved by means of a mechanical force from the actuating element 20 on the first nozzle lip 12 by means of an expansion or contraction of the thermocouple 30.

[0061] The melt 50 emerging from the nozzle outlet gap 16 is, for example, electrostatically adhered to a casting roller 40 and can then be wound into a roll in a subsequent winding device. This adhesion fixes the melt 50 to the casting roller 40. The edge of the melt 50 is characterized by the so-called neck-in, which results from the melt 50 being drawn out of the nozzle assembly 10 and from its viscoelastic behavior. As a result of the neck-in, the film width at the casting roller 40 decreases relative to the width of the nozzle outlet gap 16, and the edge region of the film thickens 70 accordingly. The reduction in film width is represented by the curved dashed lines on the melt 50.The thickening 70 is further exemplified in the characteristic thickness profile of the melt 50.

[0062] The y-axis represents the thickness of the melt 50, and the x-axis represents the nozzle width. The thickness of the melt 50 is controlled such that a constant thickness is optimally achieved along the entire nozzle width. At the right and left edges of the nozzle assembly 10, the characteristic thickening 70 of the edge occurs due to the neck-in of the melt 50. Because of electrostatic edge adhesion to the casting roller 40, a thin spot 72 can occur between the thickening 70 and a constant thickness of the melt 50, as electrostatic attraction draws melt particles from both sides. The extent of the thin spot 72 depends, for example, on the melt flow distribution at the nozzle exit gap 16, the viscoelastic behavior of the melt 50, and process settings such as the line speed, the length of the melt plume, or the strength of the edge adhesion.

[0063] The thickness profile of the melt 50 is monitored by a sensor (not shown). The sensor can be designed as an optical sensor and / or arranged on the casting roller 40, allowing conclusions to be drawn about the thickness profile of the melt 50. For this purpose, the sensor is preferably connected to the control system via data communication for the transmission of measurement signals.

[0064] By comparing the measured thickness profile with a setpoint, a base setpoint for the individual actuators 20 can be generated by the control system, such that a deviation from the setpoint is a maximum of 30%, in particular a maximum of 10%, preferably in the range of 2% to 5%. In other words, the control system can maintain a substantially constant thickness of the melt 50. For this purpose, the control system includes a data processing unit configured to process the sensor's measurement signals and, based on these, generate a control signal for the actuators 20 or the associated thermocouples 30 for adjusting the nozzle exit gap 16. In other words, the processing of the sensor's measurement signals results in the automatic control or regulation of individual, multiple, or all actuators 20 of the nozzle assembly.

[0065] For example, at least two actuators 20 can be adjusted simultaneously. This has the advantage that the simultaneous, and especially automatic, adjustment of at least two actuators 20 eliminates the need for time-consuming manual adjustment of individual actuators one after the other. Likewise, the simultaneous adjustment of two actuators 20, especially two adjacent actuators 20, reduces cross-interference between the actuators 20.

[0066] When commissioning the nozzle assembly 10 for conveying the melt 50, the adjusting elements 20 for subsequent control of the nozzle outlet gap 16 can be set to zero backlash as a starting point. This has the advantage of enabling precise adjustment of the nozzle outlet gap 16. In particular, the zero-backlash setting can be performed automatically during commissioning of the nozzle assembly 10, thus avoiding any manual intervention by an operator.

[0067] Furthermore, the right and left edge regions of the melt 50 can be monitored by the sensor and controlled or regulated in such a way that the respective edge region is adjusted by adjusting the control elements 20 depending on the material, in particular viscosity and / or viscoelasticity, and / or quality criteria and / or a conveying speed. This has the advantage that the edge region of the melt 50 located outside the net area is explicitly considered and evaluated. By monitoring the edge region of the melt 50, the entire thickness profile can be optimally adjusted. The edge region can be evaluated with regard to quality and / or stability criteria, in particular depending on the product to be manufactured and / or the production process.

[0068] Furthermore, at least one clamping blade 60 is arranged in a right-hand and left-hand edge region of the nozzle arrangement 10, whereby the width of the nozzle exit gap 16 can be variably adjusted, wherein a method for adjusting the width of the nozzle exit gap 16 and for clamping the adjusting elements 20 can be carried out automatically and comprises the following steps: Unclamping the clamping blade 60 within the nozzle outlet gap 16; moving the clamping blade 60 within the nozzle outlet gap 16; clamping the clamping blade 60 within the nozzle outlet gap 16 to fix individual actuating elements 20.

[0069] This has the advantage that the automatic adjustment of the clamping blades 60 for adjusting the width of the nozzle outlet gap 16 results in significant time savings in the production process, as no manual adjustment by the operator is required. The clamping and / or unlocking of the clamping blades 60 is achieved thermally, for example. The movement of each clamping blade 60 can be motorized and limited to a maximum adjustment torque.

[0070] Fig. 3 Figure 1 shows a schematic diagram of a control system according to the invention for the size of a nozzle outlet gap of a nozzle arrangement with simultaneous and parallel adjustment of the actuating elements. The description of the nozzle arrangement 10 is analogous to Fig. 2 .

[0071] In both diagrams, the y-axis represents the setpoint for each actuator 20, and the x-axis represents the nozzle width. Each actuator 20 is represented by a horizontal line. This indicates that several actuators 20 are positioned along the nozzle width at defined intervals. The direction of the arrows represents the adjustment of the actuators 20. An upward adjustment results in a contraction of the thermocouple 30 associated with the actuator 20, thereby exerting mechanical tension across the actuator 20 and increasing the nozzle outlet gap 16 at the corresponding location. A downward adjustment results in an extension of the thermocouple 30 associated with the actuator 20, thereby exerting mechanical pressure across the actuator 20 and decreasing the nozzle outlet gap 16 at the corresponding location.The length of the individual arrows of the actuating elements 20 describes the size of the actuating value or the amount of the strength of the adjustment.

[0072] In the diagram shown above, the control system simultaneously adjusts all actuators 20. All actuators 20 are adjusted along the entire nozzle width, including the right and left edge regions. The magnitude of the adjustment is based on the measured thickness profile of the melt 50. To compensate for deviations in the thickness profile from a constant thickness, particularly in the net area of ​​the melt 50, the actuators 20 are adjusted upwards or downwards.

[0073] In the diagram shown below, the control system simultaneously and in parallel adjusts all actuators 20. All actuators 20 are adjusted symmetrically along the entire nozzle width, particularly in the right and left edge regions. The actuators 20 are adjusted over the same stroke to enlarge the nozzle exit gap 16. Generally, the adjustment of the actuators can be made depending on the type of melt and / or the size of a basic gap in the nozzle assembly 10.

[0074] Fig. 4 Each figure shows a schematic diagram of a control system according to the invention for the size of a nozzle outlet gap of a nozzle arrangement for transmitting the setting of the actuating elements in a boundary region. The description of the nozzle arrangement 10 is analogous to Fig. 2 .

[0075] In both diagrams, the y-axis represents the setpoint for each individual actuator 20, and the x-axis represents the nozzle width. The individual actuators 20 are represented by a horizontal line. Therefore, several actuators 20 are located along the nozzle width at a defined distance from each other.

[0076] The diagram above illustrates an example of a specific setting of the adjusting elements 20 for the entire nozzle width. This specific setting can be made, for example, depending on the material of the melt, in particular its viscosity and / or viscoelasticity, and / or quality criteria and / or the conveying speed.

[0077] The diagram below illustrates how the specific setting of the actuating elements 20 in the respective boundary region from the diagram above is transferred to a reduced nozzle exit gap or a reduced nozzle width. The reduction in nozzle width is indicated by the arrows and achieved via the clamping blades 60. Before moving the clamping blades 60, it can be checked whether an adjustment of the specific setting is necessary.

[0078] The preceding explanation of the embodiment describes the present invention solely by way of examples. Naturally, individual features of the embodiment can be freely combined with one another, provided this is technically feasible, without departing from the scope of the present invention. Reference symbol list

[0079] 10 Nozzle arrangement 12 First nozzle lip 14 Second nozzle lip 16 Nozzle exit gap 20 Actuating element 30 Thermocouple 40 Casting roller 50 Melt 60 Clamping blade 70 Thickening 72 Thinning point

Claims

1. Method for automatically regulating the size of a nozzle discharge slot of a nozzle assembly, wherein the nozzle assembly has a first and a second nozzle lip and a nozzle discharge slot arranged between the nozzle lips for the controlled adjustment of a thickness profile of a conveyable melt, wherein a plurality of adjusting elements, in particular a plurality of adjusting pins, are arranged on the first nozzle lip, which are each coupled to an associated thermocouple, wherein the thermocouples can be controlled by the controller in such a way that, by expansion or contraction of the thermocouples, the slot can be adjusted by means of the action of a mechanical force applied to the first nozzle lip by the respective thermocouple via an associated adjusting element, wherein the adjusting elements are adjusted automatically on the basis of measurement signals from at least one sensor, wherein the sensor is configured and / or arranged on the nozzle assembly so as to allow conclusions to be drawn regarding the thickness profile of the melt, wherein the right-hand and left-hand marginal areas of the melt are monitored by means of the sensor and controlled or regulated by the controller in such a way that each of the marginal areas is adjusted by adjusting the adjusting elements according to the material, in particular its viscosity and / or viscoelasticity, quality criteria and a conveying speed, wherein the right-hand and left-hand marginal areas of the melt located outside a net area are explicitly considered and evaluated, wherein the right-hand and left-hand marginal areas of the melt each have a thin and a thick point.

2. Method according to claim 1, characterized in that individual adjusting elements are adjusted with a time delay.

3. Method according to claim 1, characterized in that the adjusting elements, in particular all adjusting elements, are adjusted simultaneously.

4. Method according to claim 1 or 3, characterized in that the adjusting elements, in particular all adjusting elements, are adjusted by the same stroke, thereby enabling a parallel adjustment.

5. Method according to any one of the preceding claims, characterized in that in particular when a control limit is reached, individual or multiple adjusting elements are adjusted simultaneously.

6. Method according to any one of the preceding claims, characterized in that electrostatics and / or air are used to cause the melt emerging from the nozzle assembly to adhere to the edge of a casting roller, wherein the edge adhesion, in particular the strength of the edge adhesion and / or the position on the casting roller, is adjusted by means of the controller depending on the material and / or quality criteria and / or the conveying speed.

7. Method according to claim 6, characterized in that the edge adhesion is continuously monitored and / or recorded during the operation of the nozzle assembly.

8. Method according to claim 7, characterized in that the edge adhesion is detected by means of a multidimensional motorized movement and / or an optical system and / or temperature detection of the melt on the casting roll and / or sensors for determining the thickness profile of the melt.

9. Method according to any one of the preceding claims, characterized in that the quality criteria used for the stability of the right-hand and left-hand marginal areas are a position of the thin spot, the ratio of the thin spot to the thick spot, the shape and / or form of the thin spot and thick spot, a recorded temperature curve in the right-hand and left-hand marginal areas, and a recorded curve of the film thickness in the marginal area.

10. Method according to any one of the preceding claims, characterized in that the specific setting of the adjusting elements is stored and / or integrated as a self-learning algorithm according to the material, in particular viscosity and / or viscoelasticity, and / or quality criteria and / or the conveying speed for restarting the nozzle assembly.

11. Method according to any one of the preceding claims, characterized in that on an initial operation of the nozzle assembly for conveying the melt, the adjusting elements for subsequent regulation of the slot size are set once without play as the initial setting.

12. Method according to any one of the preceding claims, characterized in that at least two adjusting elements are adjusted simultaneously.

13. Method according to any one of the preceding claims, characterized in that at least one clamping blade is arranged in each of the right-hand and left-hand marginal areas of the nozzle assembly, wherein the width of the nozzle discharge slot can be variably adjusted, the method comprising the following steps, which are carried out automatically to adjust the width of the nozzle discharge slot and to clamp the adjusting elements: unclamping the clamping blade within the nozzle discharge slot; - displacing the clamping blade within the nozzle discharge slot; - clamping the clamping blade within the nozzle discharge slot for fixing individual adjusting elements.

14. Control and / or regulating system with a control unit for executing the method according to any one of the preceding claims.