Virtual pen testing for sheet manufacturing with integrated floating rollers

Abstract

Systems and methods for non-destructively determining and reducing co-registration errors in a scanner system of a sheet manufacturing line. Features of a sheet passing through a sheet monitoring system, such as splice joints or edges of material deposited or attached on the sheet, are detected by a first scanner and a second scanner to calculate a synchronization scanner-to-machine direction positioning. Changes in machine distance between the scanners can be corrected using measurements from a tension regulating (float) roll. The machine distance between the first scanner and the second scanner is dynamically calculated and used to reduce co-registration errors. The detection method also allows for graphical display of co-registration errors without damaging the sheet material.

Description

Background Technology

[0001] In-line measurement is used to detect the properties of sheet material during manufacturing, enabling real-time control of the sheet-making process, thereby ensuring sheet quality and reducing the number of defective sheets produced. One of the main complexities of in-line measurement during sheet making is that the physical properties of the sheet material typically change in both the machine direction (MD) and the transverse direction (CD). MD refers to the direction of travel of the sheet material during manufacturing, and CD refers to the direction perpendicular to the MD across the sheet surface.

[0002] Scanning systems typically deploy scanners that traverse the CD (Disc) back and forth, while the sheet being processed during manufacturing travels along the MD (Disc). A conventional scanning system using one or more scanners delivers one or more lateral profiles to the customer, which are periodically updated at the end of each scan.

[0003] In multi-scanner systems, these scanner profiles are acquired at different locations along the manufacturing process line. Some systems cannot correlate scan positioning when a section of sheet at an upstream scanner is scanned at a downstream scanner. In other words, many conventional or existing systems cannot provide "co-point" measurements (i.e., parameters at the same point on the sheet detected by each scanner in a series of scanners). However, co-point measurements can help diagnose the root cause of nonconformities.

[0004] Therefore, there is a need for systems and methods that can perform measurements at the same point under various conditions, as well as systems and methods for proving that measurements are performed at the same point.

[0005] Overview

[0006] The inventors have recognized, among other things, the need for new and / or alternative systems and methods capable of performing same-point measurements under various conditions, as well as systems and methods for demonstrating that measurements are performed at the same point. In some exemplary examples, detectable features produced on the sheet by the manufacturing process itself are used as feature points for determining the accuracy of machine orientation (MD) distances and / or estimates in systems with multiple scanners.

[0007] A first illustrative and non-limiting example takes the form of a sheet monitoring system for use with a sheet moving in a machine direction as the sheet material undergoes a manufacturing process. The sheet monitoring system includes: a first scanner capable of moving in a lateral direction perpendicular to the machine direction, the first scanner being positioned at a first position; a tachometer monitoring the linear velocity of the sheet moving in the machine direction; a second scanner capable of moving in a lateral direction perpendicular to the machine direction, the second scanner being positioned at a second position; and a controller coupled to each of the first scanner, the tachometer, and the second scanner, and configured to receive data from each of the first scanner, the tachometer, and the second scanner. In this first exemplary and non-limiting example, the controller may be further configured to: receive from a first scanner a first timestamp when the first feature is identified by the first scanner; receive from a second scanner a second timestamp when the first feature is identified by the second scanner; receive from a tachometer data on sheet movement during the time period between the first timestamp and the second timestamp; and use the first timestamp, the second timestamp, and the data on sheet movement to determine a point of failure.

[0008] Additionally or alternatively, the manufacturing process applies a deposited material to the sheet, and this feature is the edge of the deposited material.

[0009] Additionally or alternatively, the deposited material is deposited in the form of at least two strips extending along the machine direction and separated by gaps in the transverse direction, each strip having two side edges, and this feature is a splice joint between sheets.

[0010] Additionally or alternatively, the deposited material is deposited in the form of multiple patches, each patch having a first end, a second end, a first side, and a second side, the first end and the second end being spaced apart in the machine direction, the first side and the second side being spaced apart in the lateral direction, and the feature being one of the first end or the second end.

[0011] Additionally or alternatively, the data regarding sheet movement is the speed of the sheet determined from a tachometer, and the controller is configured to use this speed and the difference between a first timestamp and a second timestamp to determine the distance the sheet has traveled.

[0012] Additionally or alternatively, the controller is associated with a memory storing the estimated machine distance between the first scanner and the second scanner, and the point-of-flight error is determined as the difference between the estimated machine distance and the determined travel distance of the sheet.

[0013] Additionally or alternatively, the controller is further configured to update the estimated machine distance in memory with the determined travel distance.

[0014] Additionally or alternatively, the data regarding sheet movement includes timestamped tachometer count data, and the controller is configured to determine the sheet travel distance by calculating the number of tachometer counts between a first timestamp and a second timestamp and multiplying the number of tachometer counts by the resolution of the tachometer.

[0015] Additionally or alternatively, the controller is associated with a memory storing the estimated machine distance between the first scanner and the second scanner, and the point-of-flight error is determined as the difference between the estimated machine distance and the determined travel distance of the sheet.

[0016] Additionally or alternatively, the controller is further configured to update the estimated machine distance in memory with the determined travel distance.

[0017] Additionally or alternatively, the system also includes a graphical display, wherein the controller is configured to generate an image showing the relationship between the point error and the scanning paths of the first and second scanners relative to the material sheet.

[0018] Additionally or alternatively, the system also includes a floating roller and a floating roller sensor having an output indicating the positioning of the floating roller used in the manufacturing process, wherein the controller is further configured to combine the output of the floating roller sensor to determine the same-point error.

[0019] Additionally or alternatively, the controller is further configured to issue control signals to adjust the speed or positioning of at least one of the first or second scanners to reduce point-of-flight errors.

[0020] Another illustrative and non-limiting example takes the form of a method for monitoring the movement of a sheet of material in the machine direction as it undergoes a manufacturing process. The method includes: at a first scanner movable in a lateral direction perpendicular to the machine direction, the first scanner being positioned at a first location, identifying a first feature on the sheet at a first time, and generating a first output signal having a second timestamp associated with the first time; at a second scanner movable in the lateral direction perpendicular to the machine direction, the second scanner being positioned at a second location, identifying the first feature on the sheet at a second time, and generating a second output signal having a second timestamp associated with the second time; at a tachometer, monitoring the movement of the sheet in the machine direction and generating an output indicating the movement of the sheet; and at a controller operatively linked to each of the first scanner, the second scanner, and the tachometer, using the first timestamp, the second timestamp, and the tachometer output to determine a point-of-flight error.

[0021] Additionally or alternatively, a stored distance estimate between the first and second scanners in the machine direction is used to synchronize the movement of the second scanner with the movement of the first scanner.

[0022] Alternatively or additionally, the determination of the point of contact error is performed by using the first timestamp, the second timestamp, and the tachometer output in the following manner: the controller uses the tachometer output to determine the distance traveled by the sheet between the first timestamp and the second timestamp; and compares the determined distance traveled with a stored distance estimate between the first scanner and the second scanner.

[0023] Additionally or alternatively, the method further includes using the determined travel distance to modify the stored distance estimate between the first scanner and the second scanner in the machine direction.

[0024] Additionally or alternatively, the method further includes reducing the same-point error by adjusting the timing or speed of one of the first or second scanners.

[0025] Additionally or alternatively, one or more patches of material are deposited on the sheet, and this feature is the edge of the deposited material.

[0026] Additionally or alternatively, this feature is a splicing joint between sheet segments.

[0027] Additionally or alternatively, the portion of the sheet between the first scanner and the second scanner engages with a floating roller having a floating roller sensor that generates a floating roller sensor output indicating the positioning of the floating roller, and the step of determining the same-point error uses the floating roller sensor output to adjust the determined same-point error.

[0028] This overview is intended to introduce the subject matter of this patent application. It is not intended to provide an exclusive or exhaustive explanation. A detailed description is included to provide further information about this patent application. Attached Figure Description

[0029] In accompanying drawings that are not necessarily drawn to scale, the same numbers may describe similar components in different views. The same numbers with different letter suffixes may represent different instances of similar components. The accompanying drawings generally illustrate the various embodiments discussed in this document by way of example rather than limitation.

[0030] Figure 1 This shows a portion of the sheet manufacturing production line;

[0031] Figure 2 This is a perspective view of an exemplary scanner used in sheet manufacturing;

[0032] Figures 3 to 4 This illustrates how the scanner passes through and scans a moving sheet of material;

[0033] Figure 5 The scanner's data capture and storage are shown;

[0034] Figure 6 The scan profiles in the lateral and machine directions are shown;

[0035] Figure 7 The method for calculating the same-point error and responding to it for system calibration is illustrated in block diagram form.

[0036] Figure 8 A graphical user interface for illustrating the same-point error is shown;

[0037] Figure 9 The diagram shows a floating roller between the two scanners;

[0038] Figure 10 A method for integrating floating roll metrics in point-of-flight error analysis and machine orientation estimation is illustrated in block diagram form; and

[0039] Figures 11A to 11B An exemplary method for integrating floating roll metrics in point-of-flight error analysis and machine orientation estimation is illustrated in block diagram form. Detailed Implementation

[0040] In-line measurement is used to detect the properties of sheet material during manufacturing, enabling real-time control of the sheet-making process, thereby ensuring sheet quality and reducing the number of defective sheets produced. One of the main complexities of in-line measurement during sheet making is that the physical properties of the sheet material typically change in both the machine direction (MD) and the transverse direction (CD). MD refers to the direction of travel of the sheet material during manufacturing, and CD refers to the direction across the sheet surface perpendicular to MD.

[0041] To detect changes in the sheet material, scanning sensors are used. These sensors periodically traverse back and forth across the sheet being processed, detecting values ​​for selected sheet properties (such as basis weight or thickness) along each scan. Typically, during each scan, the produced sheet is traversed from edge to edge. The time required for a typical scan is usually between several seconds and tens of seconds, depending on the length in the lateral direction, which can be several meters. Therefore, the rate at which such scanners provide measurement readings is typically adjustable; a typical rate is approximately one measurement reading per millisecond.

[0042] In practice, the measurement information provided by the scanning sensor is typically aggregated after each scan to provide a "profile" of the detected sheet characteristics in the lateral direction. In other words, each profile consists of a series of sheet measurements at adjacent locations in the lateral direction. The purpose of the profile is to allow for easy detection of lateral variations in sheet characteristics. Based on the detected lateral variations in the detected sheet characteristics, appropriate control adjustments can be made to the sheet forming machine to reduce profile variations in both the lateral and machine directions.

[0043] A scanning sensor that periodically traverses a sheet at a roughly constant speed cannot measure the selected sheet characteristics at a position precisely aligned perpendicular to the sheet's longitudinal edge. Due to the finite speed of the sheet, the scanning sensor actually travels obliquely across the sheet surface, resulting in a jagged pattern of continuous scan paths relative to the direction perpendicular to the sheet's longitudinal edge. In practice, the average of the profile measurements for each scan is typically calculated.

[0044] Conventional scanning systems using one or more scanners deliver one or more lateral profiles to the customer, which are periodically updated at the end of each scan. In multi-scanner systems, these scanner profiles are obtained at different MD (Metrological Determination) locations. No correlation is attempted when a sheet at an upstream scanner is actually (re)measured later by a downstream scanner. In other words, many conventional or existing systems cannot provide "co-point" measurements (i.e., parameters at the same point on the sheet detected by each scanner in a series of scanners). However, co-point measurements can help diagnose the root cause of nonconformities and offer greater accuracy because the measurements are obtained from sensors from more than one scanner.

[0045] In the manufacture of anode or cathode electrodes, metal foil from a metal roll is continuously coated with a mixture of active materials. To achieve and maintain the quality of continuous, roll-to-roll production of the electrodes, constant, online measurements of quality factors strongly correlated with battery performance are required. A cutting machine cuts the finished coated metal foil into electrode sheets, which are then assembled into the cell and battery.

[0046] With current manufacturing technologies, once a battery is assembled, there are no readily available means to identify and access specific data related to the electrodes incorporated into a particular battery. There is a need in the field for improved production traceability, enabling buyers to track online measurements taken during electrode production all the way to the assembled electrochemical cell and battery. Accurately tracking the location of features in machine orientation, along with providing simultaneous measurements of their location on the sheet, offers better traceability and enhances process monitoring capabilities.

[0047] Figure 1 A portion of a sheet manufacturing line is shown. This line is described as being used to coat metal webs or sheets used in the manufacture of electrodes for lithium-ion electrochemical cells and batteries. However, this manufacturing line can be used in any manufacturing process that utilizes sheet materials, including fabrics, other metal sheets, etc.

[0048] If the production line is used to manufacture battery electrodes, when manufacturing the anode, the electrode coating includes an anode active material such as graphite; when manufacturing the cathode, the electrode coating includes a cathode active material such as lithium metal oxide. The electrode includes a current collector metal foil coated with an electrode slurry on one or both sides of the foil. The electrode slurry may also include conductive additives, binder materials, and solvents. After the electrode slurry is applied to one side of the foil, the wet-coated foil is heated in a dryer to remove the solvent, leaving a solid layer of electrode material adhered to the metal foil. Copper foil is a preferred anode current collector material, and aluminum foil is a preferred cathode current collector material. Parameters and materials can vary considerably, and the concept of the invention is not limited to this specific context.

[0049] like Figure 1 As shown, roll 2 is unwound by an unwinder and provides a continuous sheet of material or sheet 30. The top surface (or first surface) of this sheet is coated with an electrode paste by a coating machine 4, which may include a casting coating apparatus. The basis weight, thickness, and other properties of the sheet 30 from roll 2 are generally known. In some systems, a scanner may also be positioned to measure the properties of the sheet emerging from the roll; that is, for the battery manufacturing process, the properties of the bare foil before coating can be measured and known.

[0050] Some systems, such as the one disclosed in U.S. Patent Publication 2023 / 0391571, may include markers that apply reference markers to sheet 30, and readers positioned at different points to accurately determine the MD positioning of the sheet by reading the reference markers. Such reference marking and reading systems can be expensive and consume production line space. Space is extremely valuable in manufacturing environments, and using less equipment reduces complexity, upfront costs, and maintenance and other ongoing costs. Sometimes it may even be impossible to apply reference markers because there may not be a suitable location on the sheet to place the markers; that is, the coating process may use the entire width of the sheet material.

[0051] The system and method of the present invention do not depend on the reference points from the markers and their scanning, but can be used in conjunction with such systems as needed.

[0052] The coating machine 4 includes an actuator that controls a doctor blade to adjust the amount of slurry extruded onto the sheet 30. The dryer 10 removes excess solvent and cures the slurry on the moving coated sheet 32 ​​to form an electrode layer on the sheet. Multiple coating machines 4 and / or dryers 10 may be present.

[0053] Scanner 8 measures one or more properties of the moving coated sheet entering dryer 10. Downstream on the production line, scanner 12 measures one or more properties of the moving coated sheet leaving dryer 10. In some examples, measurements at scanner 8 may be compared with measurements taken at scanner 12 as part of monitoring processes and conditions inside dryer 10. If the two measurements are taken at different locations on the sheet—for example, if a measurement at scanner 8 occurs at a different CD location than a measurement taken at scanner 12 at a given location on the MD—the difference in the initially applied coating at these two locations may interfere with the analysis of processes occurring inside dryer 10. For example, at a given location along the MD, scanner 8 may take a measurement 20 cm from the left edge of sheet 30, while scanner 12 may take a measurement 15 cm from the left edge of sheet 30.

[0054] Each scanner 8, 12 may have a tachometer nearby, such as those shown at 40, 42. As the sheet material 30 passes by, the tachometer rotates and generates a pulse sequence whose period or frequency indicates the speed of the sheet material. If, for example, the system includes one or more floating rollers (not shown) that can change the length of the sheet material between tachometers 40, 42 and thus between sensors 8, 12, the tachometer speed may vary from one location to another.

[0055] Figure 1 A very simplified manufacturing line is shown; in a more concrete implementation, it may include several coating machines 4, dryers 10, and other equipment or systems. Several layers of coating can be applied, dried, cured, etc., and these coatings can be applied to both sides of the sheet. More than two scanners 8, 10 may be present. Further operations may be performed, including cutting or slicing the sheet. In some examples, floating rollers may be included, as detailed below. A system controller 20 may be provided as the overall controller for the various components in the system, and can be connected via, for example, but not limited to, a data bus, Ethernet or other wired connections, fiber optic cables, and / or wireless communication systems (including Bluetooth). ™ It can be coupled to each of the manufacturing line systems (2, 4, 40, 8, 10, 42, 12, etc.) via WiFi or other 802.11 communication or other standards, depending on the given installation, plant, geographical location, etc., for data communication and control signal communication.

[0056] Figure 2This is a perspective view of an exemplary scanner used in sheet fabrication. Scanner 60 is configured to measure the properties of a moving sheet of material. Scanner 60 includes scanning heads 70, 72, which may, for example, encapsulate or house a radiation source and a radiation detector. The radiation source may emit radiation, such as beta rays, directed at an area on a coated sheet 90 moving on the MD. The intensity of the radiation emitted from head 70 and transmitted through the coated sheet is sensed by the radiation detector in head 72. The detector senses the amount of radiation absorbed by the coated sheet, which gives a direct indication of the material's basis weight. In this example, the radiation source emits beta radiation for measuring weight or thickness. Either or both of scanning heads 70, 72 may house an infrared sensor that detects the radiation and generates a sheet temperature profile. Other techniques may be used if desired, including those described, for example, in U.S. Patent 11,519,710.

[0057] Each scanning head 70, 72 may include a radiation source and / or a radiation detector, or both. Therefore, measurements can be performed by directing radiation from one scanning head through sheet 90 to a detector in another scanning head. If desired, measurements can also be performed using a reflection method, for example, by generating radiation at the scanning head, directing it to sheet 90, and measuring the radiation reflected back to a detector in the same scanning head.

[0058] Dual scanning heads 70 and 72 are positioned opposite each other and define a measurement gap for accommodating a sheet 90 (coated and / or uncoated) that moves on the MD. One or more motors in the scanner 60 control the movement of heads 70 and 72, respectively. The lateral movement of the dual scanning heads is synchronized in speed and direction to maintain alignment of the dual scanning heads 70 and 72. As the dual scanning heads 70 and 72 move, the system captures tachometer readings, thereby maintaining the positioning of the scanning heads relative to the sheet 90 moving on the MD. The scanner also includes positioning sensors, such as encoders or tachometers coupled to the control mechanism of the moving scanning heads 70 and 72, to provide an indication of the positioning of the scanning heads 70 and 72 at a specific time (that is, in the illustrative example, any positioning sensing measurement can be timestamped). Using such data, the instantaneous MD and CD positioning measured by the scanner can be determined.

[0059] Weight, thickness, and temperature are just examples of properties that can be measured using a scanning head. Scanning may include searching for specific chemical markers, such as detecting the presence, absence, or concentration of materials in sheets and / or coatings thereof by scanning with light of one or more wavelengths. Any suitable or desired property can be scanned, depending on the specific implementation. Different scanners and / or scanner setups may be used throughout a given manufacturing line.

[0060] In some examples, the various components of a manufacturing system include controllers and / or processors that manage the operation of each component. For example... Figure 1 As shown, the entire system can be managed by system controller 20. System controller 20 can take many forms, including, for example, a microcontroller or microprocessor coupled to memory that stores readable instructions for performing the methods described herein and provides configuration for the controller for various examples. Some examples use a computer as the system controller.

[0061] System controller 20 may include one or more application-specific integrated circuits (ASICs) to provide additional or dedicated functionality, such as, but not limited to, signal processing ASICs that can use digital filtering techniques to filter signals received from one or more sensors. It may also include logic circuits, state machines, and discrete or integrated circuit components. Those skilled in the art will recognize that many different hardware implementations can be used for the controller.

[0062] In an exemplary configuration, for example, one or more buses, fiber optic networks, Ethernet, other hardware links, and / or wireless or other communication links are provided between the various components and the system controller 20. The system controller 20 can issue commands to the various elements of the system and receive data and other feedback from each component. The system controller 20 can thus operate to synchronize the operation of various parts of the manufacturing line, including scanners, coating machines, dryers, and drive motors used to move sheet material from roll 2 through the system to an end roll (not shown) or a cutting device.

[0063] System controller 20 can be with, for example Figure 1 The rest of the system shown are separate components. Alternatively, the system controller 20 may be implemented on a controller associated with one of the various components shown in the system, for example, but not limited to, by providing a machine-readable instruction set on a non-transitory medium operatively linked to scanners, dryers, coating machines, etc., within the system. The system controller may also alternatively be implemented as a cloud-based system, such as on a remote server.

[0064] Figures 3 to 4 This demonstrates how a scanner passes through and scans a moving sheet of material. Using... Figure 1 The system shown is for reference and can be used to perform scanning at a first scanner 8, wherein the scanning head of the first scanner 8 travels back and forth across the material sheet 90, following a path as shown in 92. Although this scanning path is depicted as being entirely on the sheet, the scanning path typically also includes areas outside the sheet, so that the edges of the sheet are fully scanned.

[0065] In this example, the coating material is applied to sheet 90 in the form of patches 91, with discontinuities or gaps present on both the MD and CD. Alternatively, if desired, the coating material can be applied in strips, such that gaps exist on the CD instead of the MD. Material 90 may also include one or more splice joints, as shown at 93, where two material sheets are attached together. As the scanner travels back and forth along path 92, the edges of the patches 91 and the splice joints 93 can be detected by the scanning head, as discussed further below.

[0066] Figure 4 This illustrates how two scanners can operate in an offset manner. The path scanned by the first scanner (such as scanner 8) is shown at 92. The dashed line 94 shows the path scanned by the second scanner 12. This results in the offset shown at 96, where a distance exists between the two paths. This distance 96 can be described as a point-of-sight error. The objective could be to minimize the point-of-sight error 96. It can be seen that the scan will pass through the edges of each patch on the CD and may occasionally capture gaps between patches on the MD, as shown at 97.

[0067] Similarity errors can be minimized by controlling the actuation of each scanner. For example, during continuous operation, each scanner is expected to travel at the same speed on the CD, and the material sheet typically moves across the system on the MD at a constant speed (although the presence of floating rollers, as described below, alters the material speed by introducing local delays). By adding small delays to the movement (e.g., short pauses at edges), the travel paths can be synchronized among the various scanners to minimize similarity errors.96 Because the scan heads must be oriented, they cannot operate at a constant speed; therefore, a mismatch between scan head acceleration and speed parameters can also contribute to similarity errors. These errors can be measured and corrected using scanner encoders, as described in the various examples herein.

[0068] One control method defines the start time of the scanner's movement from the edge (as indicated at 98) based on the positioning of the material sheet 90 relative to the scanner. Other methods may be selected as needed, including, for example, increasing the speed at which the scanner moves on the CD to "catch up" with other scanners in the system, and / or omitting the scanner's lateral scan to adjust its timing.

[0069] The desired level of minimization of the same-point error may depend on the tolerances of a specific manufacturing line or quality assurance system, as well as factors such as scanner accuracy and / or spot size. In a non-limiting numerical example, if the scanner's radiation source and / or detector scans a circular area of ​​the product with a radius of 5 mm, a same-point error of less than 5 mm (96%) might be acceptable. Minimizing the offset to zero millimeters is generally not required, but each system and / or manufacturing process may have its own acceptable threshold.

[0070] One existing method for addressing and minimizing the same-point error 96 is to physically position markers or pens on the scanning heads in the manufacturing line to create physical marks on the sheet 90. The timing of the scanners on the line is then manually adjusted to calibrate each scanner until the same-point error 96 is minimized across the entire line. This process is laborious and slow, and can damage the sheet 90 as it moves through the line, resulting in product waste. Once the entire line is set up, calibration misalignments (such as due to line movement, errors, power outages, etc.) and / or process changes can occur, increasing the same-point error and requiring line shutdown for recalibration, leading to delays, waste, and other costs. Furthermore, if floating rollers are present, each movement of the floating rollers can alter the effective spacing between scanners, potentially disrupting the calibration again. Therefore, new and improved methods are needed.

[0071] Figure 5 The scanner's data capture and storage are illustrated. The scanner performs discrete measurements, which are considered as cells 100, each cell having a lateral orientation position (CD1 to CD9, as shown in 102) and a machine orientation position (MD01 to MD11, as shown in 104). In a specific implementation, there may be thousands of cells on the CD, while the number of cells in the machine orientation is essentially unlimited, as the system involved may operate continuously for extended periods (especially when the sheet is spliced ​​from one roll to the next). As the scanner travels on the CD and the sheet travels on the MD, cells marked with X are scanned. Depending on the sheet material and / or the scanner speed, there may be more than one measurement in a given CD column or MD row, although this is not always the case.

[0072] The result is an array or vector of stored values, each stored as CDn and MDmm, and a scan of “values,” which can be one or more of the weight, thickness, temperature, or any other desired parameter being measured. The parameters can be compared to desired process values ​​to monitor the process. In some examples, the measurements can provide traceability within the process for quality system purposes.

[0073] The measurements can also be used to detect features on moving sheets. For example, edges can be detected in patch or strip manufacturing. If the sheets are spliced ​​together, the splice joints can be detected. In the simplest method, comparing one sample value with the next allows the detection of edges applied to layers of the sheet. This can be understood from the shaded cells at 106 and 108. The scan values ​​at CD4 and MD04 can be represented as Wn, and the scan values ​​at CD5 and MD05 can be represented as Wn+1. An edge location can be determined if the following conditions are met:

[0074] |Wn – Wn+1| > Th edge

[0075] Among them Th edge This is the threshold used to identify edges. Next, if Wn is greater than Wn+1, this simple example will determine that a downward step from the patch / strip to the sheet has been crossed; otherwise, it's an upward step from the sheet to the patch / strip. More complex methods can be used to detect edges as needed.

[0076] Figure 6 The scan profiles are shown in the lateral and machine directions. The upper graphic 130 uses the lateral direction for positioning on the X-axis and the basis weight or thickness for comparison on the Y-axis. Here, the value measured at the first scanner during scanning across the moving sheet is shown at 132, and the value measured at the second scanner is shown at 134.

[0077] It is presumed that material deposition occurred between the two scanners. Alternatively, line 134 could represent a scan prior to drying, baking, or curing, while line 132 could represent a scan afterward. In any case, two scans are shown.

[0078] These scans represent a single sweep across the sheet material. Assuming the sheet material moves at the same speed at each scanner, and each scanner moves at the same speed on the CD, the edges of the contours can be expected to align, as shown. That is, when traversing in the lateral direction, the edges of each strip or patch should appear at the same CD location. CD scanning provides a check that the scanner and the sheet material are substantially aligned on the MD.

[0079] The lower graph 140 compares the scan profile using the machine orientation on the X-axis and the basis weight or thickness on the Y-axis. This is precisely where edge differences can be used to provide a point-of-scan. The result of the first scan is shown at 142, and the result of the second scan is shown at 144. As the material moves, if point-of-scan errors exist, the scanner will detect these edges at different locations in the machine orientation. This difference is shown at 146.

[0080] At 150, the system parameter is shown as the estimated difference (ΔMD) in the MD counts between the positioning of the first and second scanners. An initial value for ΔMD can be entered into the system during initial installation if needed, or calibration can be performed, for example, when sheet splice joints or intentionally placed markers / edges on the sheet pass through the system. This initial value can then be adjusted manually or automatically up or down by first identifying the distance between the edge detections of the two scanners, as shown at 146, and then correcting the estimated ΔMD to minimize point-of-flight errors.

[0081] As a stored value, ΔMD can represent the number of units between the two scanners in the machine direction (see [reference]). Figure 5In the example shown, if each cell has a length of 1 mm on the MD, then the distance will be 3.551 meters when the value of ΔMD is as shown at position 152. That is, according to the stored ΔMD, the two scanners in the system are separated by a sheet of material of 3.551 meters. If from Figure 6 If a point-of-flight error is identified among the detected features, the stored ΔMD is adjusted upwards or downwards. In the example shown, the second scanner (contour 144) detects the edge on the MD earlier than the first scanner (contour 142). Increasing the stored value of ΔMD will reduce the point-of-flight error.

[0082] When the stored value ΔMD changes, the system responds by adjusting the timing of the scanners. Increasing ΔMD will cause the system to either reduce the latency used by the first scanner or increase the latency of the second scanner, thereby reducing the point-of-flight error 146. That is, in some examples, each scanner is able to operate in a scan-delayed manner, during which the scanner stays at the edge for a period of time. To adjust in response to changes in ΔMD, additional or reduced latency can be used in one iteration of the scanner's sweep (or more iterations as needed). In other examples, the scanners operate in normal mode without any introduced edge latency, but when adjustment is required, one or more scanners add latency in response to requested or commanded adjustments.

[0083] Therefore, in this example, features detected on the sheet material (edges of patches or strips deposited thereon, but seams or splices may also be used) are used to identify and determine / measure the same-point error. The system (e.g., embodied by a controller operating based on stored machine-readable instructions) responds by adjusting to reduce the same-point error via scanners in the control system. Feature detection can be used similarly to calibration, allowing the MD positioning measurements themselves to be used to determine the same-point error.

[0084] The detected features can be any of the following: strip edges, patch edges, patch gaps (gaps between patches on the MD), splice joints, or intentionally placed markers. Some systems may use features that indicate changes in sheet properties detectable on the MD, rather than those detectable only on the CD, because such changes provide information about the MD that should be repeatedly detected as the sheet moves through the manufacturing line. Intentionally placed markers may include, for example, a piece of deposited material that spans most or all of the material sheet, placed for the purpose of being detected by a scanner. Placed markers may be made of a material that is unaffected by or at least compatible with the processes in the system (i.e., does not disrupt the processes in the system), and preferably will not contaminate and / or otherwise affect the rest of the material sheet, fixtures in the system, rollers, etc. For example, placed markers may be positioned in patch gaps, or, if necessary, near splice joints, and then removed before further processing of the material strip. If necessary, placed markers may also be positioned on or above strips or patches, although this may mean discarding one or more portions of the manufactured material sheet. Additionally or alternatively, the marker may be positioned at the edge of the sheet.

[0085] If a patch procedure is used, and the scanner's scan path traverses the gaps between patches on the MD, then a CD scan at 130 may (at least partially) resemble an MD scan at 140. Figure 4 An example is shown at point 97. Similarly, if a point error is identified, the system can respond by adjusting ΔMD.

[0086] Figure 7 A method for calculating and responding to the same-point error is illustrated in block diagram form. In an illustrative example, at 200, a first scanner (“Scanner 1”) detects a feature on the material sheet, such as a strip edge, patch edge, patch gap, splice joint, or intentionally placed marker. Scanner 1 then transmits this information to the system controller as indicated at 202. This transmission may indicate that a feature has been detected, such as by transmitting a first timestamp and tachometer count at which the feature was detected at Scanner 1, and / or the output from a first tachometer associated with (preferably adjacent to) Scanner 1. The tachometer output may indicate, for example, but not limited to, the speed at which the sheet material moves past the tachometer and MD positioning.

[0087] Next, at position 204, another scanner (“Scanner 2”) also detects the feature. Preferably, the same feature is detected at both positions 200 and 204; to ensure this, an existing or initial calibration can be provided to the system, approximating the ΔMD between scanner 1 and scanner 2. The operation at position 204 is not necessarily a command step; the feature may be detected as part of the scanner’s standard operation or through post-scan analysis. In practice, Figure 7 The operation does not need to occur in real time, although it may preferably be performed over a short period of time (e.g., 30 seconds to 2 minutes, or slightly more or less, depending on the production line speed and / or the distance between scanners on the MD, as this period may be the time required for a given detectable feature to be transferred from one scanner to the next) so that adjustments can be made promptly when needed. Like scanner 1, scanner 2 transmits data to the system controller as indicated at 206. This transmission may also include, for example, a timestamp and / or the output from a second tachometer associated with scanner 2.

[0088] In some examples, the system controller may also request scanner 2 to transmit the tachometer count from the second tachometer based on the time indicated by the first timestamp from scanner 1. In other examples, the system controller may obtain the tachometer count from the first tachometer based on the time indicated by the second timestamp from scanner 2. These additional data points may be omitted if necessary. In some examples, both timestamps and the sheet material velocity from one of the two tachometers are used.

[0089] At point 208, the system controller determines the tachometer counts, referred to as LS1 (first tachometer count) and LS2 (second tachometer count). Taking one of these tachometers on the production line as an example, LS1 is the count of that tachometer at the first timestamp, and LS2 is the count of the same tachometer at the second timestamp. The tachometer counts can be determined by examining the tachometer output data, which can be in the form of a sequence of tachometer counts reported in chronological order, with each entry in the sequence accompanied by a timestamp.

[0090] Next, at 210, ΔMD is calculated using the tachometer count and tachometer resolution (which can be determined, for example, in millimeters per count). In other examples, if the sheet speed is monitored and reported along with one of the timestamps, and no indication is received that the sheet speed has changed between the first and second timestamps, ΔMD can be calculated by multiplying the sheet speed by the difference between the two timestamps, instead of using LS1, LS2, and the tachometer resolution.

[0091] Therefore, the calculated ΔMD represents the distance the sheet traveled during the time period between the first and second timestamps. Then, the calculated ΔMD is compared with the stored ΔMD. D The latter is compared to the system controller's estimate of the true distance between the two scanners in the machine direction. If the calculated ΔMD is compared with the stored ΔMD... D If they differ, adjustments can be made to scanner 1 or scanner 2 as indicated at point 214. Then the stored ΔMD... D Update to the calculated ΔMD value.

[0092] Figure 7 The process shown involves two scanners. More than two scanners can be used, in which case steps 200 / 202 or 204 / 206 can be repeated for each scanner in the system. Multiple ΔMD values ​​will then be generated. For more than two scanners, the ΔMD values ​​can be determined by referring to a single scanner in the system (which can be the first scanner in the process path, or any scanner), or they can be calculated sequentially from one scanner to the next as needed.

[0093] like Figure 7 The process described in the associated text can be performed using a system controller. Alternatively, a scanner or another device in the system can acquire or receive data (e.g., where other systematic connections to the bus or data feed are available) and perform the method.

[0094] Alternatively or additionally, the system controller, as indicated at 216, displays a virtual pen test to the user (such as a plant technician or quality system representative) to virtually show the same-point error, such as... Figure 8 As indicated. Figure 8 An exemplary graphical user interface for illustrating the same-point error is shown. The display, as shown at 250, illustrates (either an actual photograph or a graphical representation) a material sheet 252 with identifiable features 254.

[0095] The feature shown in the example is a patch; alternatively or otherwise, stripes, applied markers, and / or splices may also be shown; other features used in the sheet manufacturing process may be shown as needed. A set of lines, such as those at 256, 258, and 260, corresponding to scanners 3, 2, and 1, are then displayed on display 250 using the ΔMD value measured by each scanner. These lines graphically illustrate the common-point error for each scanner, i.e., the different paths taken by each scanner. Information about CD positioning (such as information from the CD encoder or other sensors) is integrated into this graphical illustration of the common-point error and may also be shown on the user interface as needed (e.g., displayed separately, or paired with MD in numerical coordinates).

[0096] This display is a "virtual" pen test because it represents what a physical pen test would observe, but does so without damaging the sheet material product. The user can move the cursor shown at position 262. Display 250 includes a graph as shown at position 264, which provides the numerical point error of each scanner line at the cursor position in the example.

[0097] Trend graphs of errors at the same point between scanners can also be displayed. For example, variations in sheet material (e.g., stretching) may be detected using these methods. Depending on the resolution of the measurement and tachometer, minute variations that may affect calibration or indicate problems (including malfunctions) in the product or fixture may be detected.

[0098] Display 250 is generated by setting a scanner as the “baseline” for the illustrated MD location (note the MD line on the left) and illustrating the edges of the stripe or patch 254 at the MD and CD locations for that baseline scanner (here, scanner 3, line 256). For the next scanner (scanner 2, line 258), the ΔMD and edge intersection points observed, determined, or measured for that scanner are identified from the scanner data and then used to plot line 258. This process is repeated for each scanner. Using MD and / or tachometer resolution, the ΔMD value shown at 264 can be calculated in a suitable unit of measurement (e.g., millimeters as shown).

[0099] The results are more accurate, less costly, and less destructive than calibration using physical pens. Achieving millimeter-level resolution using physical pens is difficult, if not impossible, especially when different types of scanners are used in manufacturing lines. Furthermore, the process is repeatable at will, requiring no line stop-start or manual intervention or measurement. In fact, recalibration can be performed on command and / or as planned, and even continuously if necessary.

[0100] Figure 9 A floating roller is shown between the two scanners. Analytical or virtual pen tests used to illustrate and minimize point-of-failure errors also have the capability to further consider the positioning of the floating roller. Sheet material 300 is seen passing through a first scanner 302 with a first tachometer 304. The sheet material 300 enters a processing apparatus 310, which can be any processing apparatus used to manipulate the sheet 300 during the manufacturing process, including baking or curing instruments, coating machines, etc. After leaving the processing apparatus 310 (which may be omitted if desired), a floating roller 320 is used to control the tension of the sheet 300 as it passes through the process. The sheet 300 then enters a second scanner 330 with a second tachometer 332.

[0101] Those skilled in the art will recognize the many uses of the floating roller 320 in the sheet manufacturing process. One common use is to maintain the required level of tension on the sheet material 300. The floating roller 320 is positioned on an arm 322, and a sensor 324 monitors the positioning of the floating roller 324. As shown at 326, the arm 322 can move up and down to absorb slack and maintain the required level of tension. However, as the floating roller 320 moves, the length of the sheet material 300 between the two scanners 302, 330 changes.

[0102] Therefore, the system provides the ability to dynamically monitor and adjust to automatically adapt to changes in ΔMD between scanners 302 and 330. Changes in ΔMD between scanners can be updated using a sensor 324 from the floating roller 320. This is achieved by adjusting the estimated ΔMD using the output of sensor 324, and then adjusting the scanning timing of the second scanner 330 to minimize point-of-flight errors. Such modifications will then have an impact on the remaining scanners downstream of scanner 330 in the system.

[0103] Figure 10 and Figures 11A to 11B An exemplary method for integrating floating roll metrics in point-of-flight error analysis and machine orientation estimation is illustrated in block diagram form. Figure 10 A first example is shown. For calibration, the floating roller is positioned and fixed at the desired positioning Y0. The process is then performed in conjunction with... Figure 7 Similarly, scanner 1 detects features such as strip edges, patch edges, patch gaps (gaps between patches on the MD), splice joints, or intentionally placed markers, as indicated at 352. Scanner 1 transmits the occurrence of the detected feature to, for example, a system controller at frame 354. Scanner 2 also detects the feature as indicated at 356 and generates a transmission to the system controller at 358. This transmission may include one or more of a tachometer count and / or a timestamp at the time the feature was detected.

[0104] The system controller (or, if not the system controller, any device performing the analysis) determines tachometer counts LS1 and LS2, representing the first detection at box 352 and the second detection at box 356, as indicated at 360. The system controller (or other device) then determines the baseline ΔMD0 by multiplying the difference between LS1 and LS2 by the tachometer resolution (TRes), as indicated at 362.

[0105] For continuous operation, the floating roller is released from its fixed position. As shown at 370, the actual floating roller position Y1 is monitored. Then, as shown at 372, the current ΔMD value is determined by subtracting the change in floating roller position from the baseline ΔMD0 (here multiplied by two, assuming...). Figure 9The floating roller shown has a dual effect on ΔMD due to its movement. The system then adjusts the operation of scanner 2 as indicated at 374 to accommodate the current floating roller positioning. This can also generate... Figure 8 The display shown is as indicated at position 376.

[0106] Although Figure 10 The example illustrates how a floating roller can be integrated into the analysis, but it can be noted that calibration is slightly more difficult when a floating roller is present. However, it should also be noted that calibration can be performed on a post-hoc basis using captured data. This approach can be a triggered analysis, rather than fixing the floating roller positioning at box 350, where captured data on detected features, timestamps, and / or tachometer counts can be analyzed to estimate the point-of-flight error and / or ΔMD if the floating roller positioning is observed to remain constant over a sufficiently long period (long enough to allow features to be transferred from one scanner to the next) of time. Therefore, assuming the floating roller positioning remains stable over a minimum time period (typically less than one minute), recalibration can be performed without disrupting the system process. In some examples, recalibration can be performed even if the floating roller is moving, provided that the initial and final floating roller positioning are available.

[0107] Figures 11A to 11B Another example is shown. Here, instead of using a floating roller positioning sensor as a measuring device for adjustment, the output of the floating roller is used to fill a lookup table or form a model. Starting at 400, the floating roller positioning is observed and recorded as DRPn. The method continues, and scanner 1 detects features such as strip edges, patch edges, patch gaps (gaps between patches on the MD), splice joints, or intentionally placed markers, as indicated at 402. Scanner 1 transmits the occurrence of the detected feature to, for example, a system controller at box 404.

[0108] Scanner 2, as indicated at 406, also detects the feature and generates a transmission to the system controller at 408. This transmission may include one or more of the tachometer count and / or timestamp at the time the feature was detected. The system controller (or, if not the system controller, any device performing the analysis) determines tachometer counts LS1 and LS2, representing the first and second detections at block 402, respectively, as shown at 410. The system controller (or other device) then determines the baseline ΔMDn by multiplying the difference between LS1 and LS2 by the tachometer resolution (TRes), as indicated at 412.

[0109] In some examples, the method then stores the paired values ​​ΔMDn and DRPn, as indicated at 414. For example, these values ​​could be stored as lookup values ​​so that when a specific floating roller position (DRPn) occurs, [the relevant information is missing]. Figure 11BThe estimated ΔMDn associated with that specific location is used. Therefore, ΔMD can be used to adjust the scanner release (the time to initiate a scanner sweep) based on the tracked changes in ΔMD, thereby achieving more accurate same-point functionality.

[0110] In other examples, the method forms ΔMD as a functional model of the floating roller positioning DRP, as indicated at 416. For example, best-fit analysis can be used; any suitable formula complexity can be used, such as first-order (e.g., ΔMDn = a + b). DRP (Dual Ranking Probability), second-order analysis, or any suitable or desired model type. If so, use that model to estimate ΔMD for any input floating roller positioning.

[0111] When a new floating roller position is observed, as indicated at 418, another iteration of the method in blocks 402, 404, 406, 408, 410, and 412 is performed to produce another pair of ΔMDn+1 and DRPn+1 values. This method can be iterated frequently and multiple times as needed.

[0112] During operation, Figure 11A The method can be as follows Figure 11B This is implemented as shown. Here, the floating roller positioning, DRPi, is monitored at box 430. As indicated at 432, an estimate of ΔMD is found using a lookup table (and possibly interpolation if necessary) and / or a model. Then, as indicated at 434, the estimated ΔMD is used to adjust the operation of one or more scanners. This estimated ΔMD can also be used to update the display of the process, as indicated at 436.

[0113] Each of these non-restricted examples may exist independently, or may be combined with one or more other examples in various permutations or combinations.

[0114] The above detailed description includes reference to the accompanying drawings, which form part of the detailed description. These drawings illustrate specific embodiments by way of illustration. These embodiments are also referred to herein as “examples.” Such examples may include elements other than those shown or described. However, the inventors also contemplate examples in which only those elements shown or described are provided. Furthermore, the inventors contemplate examples using any combination or arrangement of those elements (or one or more aspects thereof) shown or described relative to a particular example (or one or more aspects thereof) or relative to other examples (or one or more aspects thereof) shown or described herein.

[0115] In the event of any inconsistency between this document and any other document incorporated by reference, the purpose described in this document shall prevail.

[0116] In this document, as is common in patent documents, the terms “a” or “an” are used to include one or more, and are not related to any other instance or use of “at least one” or “one or more”. Furthermore, in the claims, the terms “first,” “second,” and “third,” etc., are used merely as labels and are not intended to impose numerical requirements on their objects.

[0117] The method examples described herein can be implemented at least in part by a machine or computer. Some examples may include computer-readable or machine-readable media encoded with instructions operable to configure an electronic device to perform the methods described in the examples above. Specific implementations of such methods may include code, such as microcode, assembly language code, or high-level language code. Such code may include computer-readable instructions for performing various methods. The code may form part of a computer program product. Furthermore, in one example, the code may be tangibly stored on one or more volatile, non-transient, or non-volatile tangible computer-readable media, such as during execution or at other times. Examples of such tangible computer-readable media may include, but are not limited to, hard disks, removable disks or optical discs, magnetic tape cassettes, memory cards or memory sticks, random access memory (RAM), read-only memory (ROM), etc.

[0118] The above description is intended to be illustrative and not restrictive. For example, the examples (or one or more aspects thereof) described above may be used in combination with each other. Other embodiments may be used by those skilled in the art upon viewing the above description. This summary is provided to comply with 37 CFR. 1.72(b), and allows the reader to quickly determine the nature of the technical disclosure. It should be understood that it is not intended to interpret or limit the scope or meaning of the claims.

[0119] Furthermore, in the above-described embodiments, various features may be grouped together to simplify this disclosure. This should not be construed as an intention that any unclaimed features disclosed are essential to any claim. Rather, the subject matter of the invention may include fewer features than those of the specific embodiments disclosed. Therefore, the following claims are incorporated herein by reference as examples or embodiments, wherein each claim is itself a separate embodiment, and such embodiments are contemplated to be combined with each other in various combinations or arrangements. The scope of protection should be determined with reference to the appended claims and the full scope of the equivalents conferred by such claims.

Claims

1. A sheet monitoring system for use with a sheet moving in a machine direction during a manufacturing process, the sheet monitoring system comprising: A first scanner, the first scanner being movable in a lateral direction perpendicular to the direction of the machine, the first scanner being positioned at a first position; A tachometer that monitors the linear velocity of the sheet moving in the machine direction; A second scanner, which is movable in the lateral direction perpendicular to the machine direction, is positioned at a second position; and A controller, coupled to each of the first scanner, the tachometer, and the second scanner, and configured to receive data from each of the first scanner, the tachometer, and the second scanner, wherein the controller is configured to: Receive a first timestamp from the first scanner when the first feature is recognized by the first scanner; Receive a second timestamp from the second scanner when the first feature is recognized by the second scanner; Receive data from the tachometer regarding the sheet movement during the time period between the first timestamp and the second timestamp; as well as The first and second timestamps, along with the data regarding sheet movement, are used to determine the point of failure.

2. The sheet monitoring system of claim 1, wherein the manufacturing process applies a deposited material to the sheet, and the feature is one of the following: The edge of the deposited material; or Joints between sheets.

3. The sheet monitoring system of claim 1, wherein the data regarding sheet movement is the speed of the sheet determined from the tachometer, and the controller is configured to use the speed and the difference between the first timestamp and the second timestamp to determine the distance traveled by the sheet.

4. The sheet monitoring system of claim 3, wherein the controller is associated with a memory storing an estimated machine distance between the first scanner and the second scanner, and the point-of-flight error is determined as the difference between the estimated machine distance and the determined travel distance of the sheet; and Optionally, the controller is further configured to update the estimated machine distance in the memory with the determined travel distance.

5. The sheet monitoring system of claim 1, wherein the data relating to sheet movement includes timestamped tachometer count data, and the controller is configured to determine the distance traveled by the sheet by calculating the number of tachometer counts between the first timestamp and the second timestamp and multiplying the number of tachometer counts by the resolution of the tachometer.

6. The sheet monitoring system of claim 5, wherein the controller is associated with a memory storing an estimated machine distance between the first scanner and the second scanner, and the point-of-flight error is determined as the difference between the estimated machine distance and the determined travel distance of the sheet; and Optionally, the controller is further configured to update the estimated machine distance in the memory with the determined travel distance.

7. The sheet monitoring system according to any one of claims 1 to 6, further comprising a graphical display, wherein the controller is configured to generate an image showing the relationship between the point error and the scanning paths of the first scanner and the second scanner relative to the material sheet.

8. The sheet monitoring system according to any one of claims 1 to 6, the sheet monitoring system further comprising a floating roller and a floating roller sensor, the floating roller sensor having an output indicating the positioning of the floating roller used in the manufacturing process, wherein the controller is further configured to determine the same-point error by incorporating the output of the floating roller sensor.

9. The sheet monitoring system according to any one of claims 1 to 6, wherein the controller is further configured to issue a control signal to adjust the speed or positioning of at least one of the first scanner or the second scanner to reduce the point-of-flight error.

10. A method for monitoring the movement of said sheet in a machine direction during a manufacturing process, the method comprising: At a first scanner that is capable of moving in a lateral direction perpendicular to the machine direction, the first scanner is positioned at a first location, identifies a first feature on the sheet at a first time, and generates a first output signal having a second timestamp associated with the first time; At a second scanner that is capable of moving in a lateral direction perpendicular to the machine direction, the second scanner is positioned at a second location, identifies the first feature on the sheet at a second time, and generates a second output signal having a second timestamp associated with the second time; At the tachometer, the motion of the sheet moving in the machine direction is monitored and an output indicating the motion of the sheet is generated; At a controller operatively linked to each of the first scanner, the second scanner, and the tachometer, the first timestamp, the second timestamp, and the tachometer output are used to determine the point of failure.

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