MULTI-ROLLER REGISTERED REPEAT DEFECT DETECTION OF A WEB PROCESS LINE

• US 20100063750A1
• Filed: 09/10/2008
• Published: 03/11/2010
• Est. Priority Date: 09/10/2008
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: FLOEDER, Steven P., Skeps, Carl J., Masterman, James A., Okonek, Terry A.
• Granted Patent: US 7,797,133 B2
• Time in Patent Office: Days
• US Class Current: 702/35
• CPC Class Codes: B65H 2301/542 Quality control
• CPC Class Codes: B65H 2557/62 for web tracking, i.e. retrieving a certain position of a web
• CPC Class Codes: G01N 2021/8917 Paper, also ondulated
• CPC Class Codes: G01N 2021/8918 Metal
• CPC Class Codes: G01N 21/89 in moving material, e.g. running paper or textiles G01N21/90, G01N21/91, G01N21/94 take precedence
• CPC Class Codes: G01N 21/8915 non-woven textile material
• CPC Class Codes: G01N 21/8922 Periodic flaws

Abstract

A manufacturing system includes rollers having synchronization marks to indicate complete rotations. Synchronization mark readers read the synchronization marks of the plurality of rollers and output roll synchronization signals. An encoder outputs a position signal indicative of a down-web distance of the web. An inspection system inspects the web and outputs anomaly data identifying positions of anomalies on the web. A synchronization unit receives the position signal from the encoder and the plurality of roll synchronization signals from the synchronization mark readers and converts the occurrence of each of the roll synchronization signals into down-web positions within a coordinate system associated with web process line. An analysis computer processes the anomaly data and the synchronization signals to identify repeated anomalies and to determine which of the rollers caused the repeated anomalies.

Claims

1. A method comprising:

receiving roll synchronization signals from a plurality of sensors of a web manufacturing system, wherein each of the sensors corresponds to a different roller of the web manufacturing system, and wherein each of the roll synchronization signals indicates that the corresponding roller has completed a full rotation during manufacturing of a web of material;

identifying positions of the roll synchronization signals with respect to the web;

receiving anomaly data from a web inspection system that identifies positions of anomalies on the web;

identifying a set of two or more of the anomalies as repeated anomalies;

identifying which of the rollers caused the repeated anomalies by correlating the positions of the repeated anomalies with the positions of the roll synchronization signals; and

outputting an identification of the identified one of the rollers.

2. The method of claim 1, wherein identifying which of the rollers caused the repeated anomalies comprises:

for each of the rollers,

(i) defining a plurality of sequential segments in a downweb direction of the web for the roller, wherein the segments are defined to have an equal length in the down-web direction, and wherein the length of the segments is defined to be equal to a distance corresponding to the completed rotations of the rollers as indicated by the roll synchronization for the roller; and

(ii) determining that the rollers caused the repeated anomalies when the repeated anomalies occur at a substantially equal cross-web position and a substantially equal down-web distance from a beginning of at least a threshold number of the segments for the first one of the rollers.

3. The method of claim 1, wherein outputting further comprises outputting coordinates of the at least one of the anomalies, wherein the coordinates include the cross-web position of the at least one of the anomalies and the down-web distance from the beginning of each of the segments of the at least one of the anomalies.

4. The method of claim 1, wherein identifying which of the rollers caused the repeated anomalies comprises:

determining a first anomaly position of a first one of the anomalies, a second anomaly position of a second one of the anomalies, and a third anomaly position of a third one of the anomalies; and

determining that the first one of the anomalies, the second one of the anomalies and the third one of the anomalies are repeated anomalies caused by the first one of the rollers when;

(i) the first anomaly position, the second anomaly position and the third anomaly position have a common cross-web position, (ii) are each separated in the down-web direction by a distance greater than a predetermined minimum distance defined by a circumference of a smallest one of the rollers, and (iii) the third anomaly occurs at a down-web position that is an multiple of a down-web distance between the first anomaly position and the second anomaly position.

5. The method of claim 4, wherein the first multiple is one of one-third, one-half, one, two, or three.

6. The method of claim 4, further comprising determining a fourth anomaly position of a fourth one of the anomalies that has the same cross-web position as that of the first anomaly position and that occurs at a down-web position that is a second multiple of the down-web distance between the first anomaly position and the second anomaly position.

7. The method of claim 1, wherein identifying which of the rollers caused the repeated anomalies comprises:

determining a first anomaly position of a first one of the anomalies and a second anomaly position of a second one of the anomalies;

determining a down web distance between the first anomaly position and the second anomaly position;

determining an expected down web position of a completed rotation of the first one of the rollers by adding the determined down web distance to a position on the web corresponding to a first completed rotation of the first one of the rollers;

determining an error by subtracting the expected position from an actual position for a completed rotation of a first one of the rollers as determined from the roll synchronization signal for the first one of the rollers; and

determining that the first one of the rollers caused the repeated anomalies when the error is below a predetermined tolerance level.

8. The method of claim 1, wherein determining that one of the rollers caused at least one of the anomalies comprises:

obtaining a circumference of the one of the rollers;

creating a composite map that represents a number of the segments of the web, wherein the composite map has a length dimension proportionate to the length of the segments and a width dimension proportionate to the width of the segments;

identifying positions of anomalies on the composite map in accordance with positions of the anomalies on the segments; and

determining that the one of the rollers caused at least one of the anomalies when a subset of the anomalies that includes the at least one of the anomalies occur at a certain position on the composite map a threshold number of times.

9. The method of claim 8, wherein determining comprises determining that the one of the rollers caused the at least one of the anomalies when the at least one of the anomalies occurs at the certain position on the composite map for at least one-half of the number of segments.

10. The method of claim 8, further comprising outputting the composite map such that positions of the anomalies are identified in accordance with a number of occurrences of each of the anomalies at each of the positions and an action for a user to take with respect to the one of the rollers.

11. The method of claim 1, wherein identifying a set of two or more of the anomalies as repeated anomalies comprises:

defining a plurality of sequential lanes in a crossweb direction of the web; and

separately processing inspection data for each of the lanes to identify any repeated anomalies within each of the lanes.

12. The method of claim 1, wherein outputting an identification of the identified one of the rollers comprises:

associating each of the repeating anomalies with the identified roller as causing the repeated anomaly; and

outputting each of the repeating anomalies and the associated roller causing the repeated anomaly.

13. The method of claim 1, wherein anomalies are potential or actual defects.

14. A method comprising:

for a web manufacturing system having a plurality of roller to transport a web of material, storing data specifying for each of the rollers a side of the web on which the roller is located;

when transporting the web, receiving roll synchronization signals from a plurality of sensors, wherein each of the sensors corresponds to a different one of the rollers, and wherein each of the roll synchronization signals indicates that the corresponding roller has completed a full rotation;

identifying positions of the roll synchronization signals with respect to the web;

receiving anomaly data from a web inspection system that identifies positions of anomalies on the web;

identifying a set of two or more of the anomalies as repeated anomalies;

identifying which of the rollers caused the repeated anomalies by correlating the positions of the repeated anomalies with the positions of the roll synchronization signals;

determining on which side of the web the identified roller is located; and

outputting an data indicating the side of the web the identified roller is located.

15. A system comprising:

a plurality of rollers in contact with a web of material, wherein two or more of the rollers each include a synchronization mark to indicate when the corresponding roller has completed a full rotation;

a plurality of synchronization mark readers that read the synchronization marks of the plurality of rollers and output roll synchronization signals, wherein each of the roll synchronization signals indicates that the corresponding roller has completed a full rotation during manufacturing of the web;

an encoder on at least one of the rollers that outputs a position signal indicative of a down-web distance of the web;

an inspection system that inspects the web and outputs anomaly data identifying positions of anomalies on the web;

a synchronization unit that receives the position signal from the encoder and the plurality of roll synchronization signals from the synchronization mark readers, wherein the synchronization unit converts the occurrence of each of the roll synchronization signals into down-web positions within a coordinate system associated with web process line; and

an analysis computer that processes the anomaly data to identify a set of two or more of the anomalies as repeated anomalies, wherein the analysis computer outputs an indication of which of the rollers caused the repeated anomalies by correlating the positions of the repeated anomalies with the down-web positions of the roll synchronization signals.

16. The system of claim 15,

wherein the analysis computer identifies a first one of the anomalies at a first anomaly position, a second one of the anomalies at a second anomaly position, a third one of the anomalies at a third anomaly position, and a fourth one of the anomalies at a fourth anomaly position,

wherein each of the first anomaly position, the second anomaly position, the third anomaly position, and the fourth anomaly position occur at a common cross-web position,

wherein the first anomaly position and the second anomaly position are separated by a first distance in the down-web direction, the second anomaly position and the third anomaly position are separated by a second distance in the down-web direction that is a first multiple of the first distance, and the third anomaly position and the fourth anomaly position are separated by a third distance in the down-web direction that is a second multiple of the first distance.

17. The system of claim 15, wherein the first multiple and the second multiple are one of one-third, one-half, one, two, or three.

18. The system of claim 15, wherein the analysis computer determines a distance between two of the repeated anomalies, determines a first rotation position on the web corresponding to a rotation of a first one of the rollers, determines an estimated down-web roller position for a subsequent rotation of the first one of the rollers by adding the distance between the two repeated anomalies to the first rotation position, determines an error by subtracting the estimated down-web roller position for the first one of the rollers from an actual roller position determined by the synchronization unit, and determines that the first one of the rollers caused the repeated anomalies when the error is below a predetermined tolerance level.

19. The system of claim 15,

wherein, for each of the rollers having a synchronization mark, the analysis computer:

(i) defines a number of segments of the web such that each of the segments has a length in the down-web direction defined by the circumference of the roller, and

(ii) forms a composite map that has a length dimension proportionate to the length of the segments and identifies positions of anomalies on the composite map in accordance with positions of the anomalies within each of the segments, and

wherein the analysis computer determines which of the rollers caused the repeated anomalies when the at least one of the anomalies occurs in the composite map for that roller at least a threshold number of times.

20. The system of claim 19, wherein the threshold number of times is a majority of the number of the segments.

21. The system of claim 19, further comprising a user interface that displays the composite map, a representation of a number of occurrences of each of the anomalies of the segments at each position, and a suggested action for a user to take with respect to the one of the rollers.

22. A computer-readable medium comprising instructions for causing a programmable processor to:

receive signals from sensors of a web manufacturing system, wherein each of the sensors corresponds to a roller of the web manufacturing system, and wherein each of the sensors sends a signal when the corresponding roller has completed a full rotation during manufacturing of a web of material;

identify positions of the roll synchronization signals with respect to the web;

determine segments of the web, wherein a distance between the positions of the roll synchronization signals corresponding to the completed rotations of each of the rollers defines the length of the segments in the down-web direction;

receive anomaly data from a web inspection system that identifies positions of anomalies on the web;

identify corresponding positions of the anomalies on each of the segments;

determine that one of the rollers caused at least one of the anomalies when a subset of the anomalies that includes the at least one of the anomalies repeatedly occur at a certain cross-web position and a certain down-web distance from the beginning of each of the segments for a threshold number of the segments; and

output an identification of the one of the rollers.