Accurate Tracking Of Web Features Through Converting Processes

• US 20090088889A1
• Filed: 09/24/2008
• Published: 04/02/2009
• Est. Priority Date: 09/27/2007
• Status: Active Grant

• Current Assignee: ABB Limited
• Original Assignee: ABB Limited
• Inventors: Hellstrom, Ake, Huotilainen, Tommi, Saarela, Antti
• Granted Patent: US 8,060,234 B2
• Time in Patent Office: Days
• US Class Current: 700/127
• CPC Class Codes: B65H 2557/62 for web tracking, i.e. retrieving a certain position of a web
• CPC Class Codes: B65H 26/02 responsive to presence of irregularities in running webs
• CPC Class Codes: D21G 9/0009 Paper-making control systems
• CPC Class Codes: G01N 21/89 in moving material, e.g. running paper or textiles G01N21/90, G01N21/91, G01N21/94 take precedence

Abstract

There is described a method and apparatus for tracking the location of web features through a converting process, one application of which can involve tracking paper defects from a paper machine as detected by a camera system, to a winder where the sheet is wound to rolls so that the web defects can be repaired in the winder before making the rolls. The method to track web features is based on pattern identification of inherent sheet variability or defects. The apparatus involves two or more sheet property or defect monitoring web sensors arranged at the same cross directional location at different stages of the converting operation, augmented by tachometers and/or roll diameter sensors. A full automation system for drive control on the winder based on this information is preferably added to make maximum advantage of this information.

Claims

1. A system for tracking features of a moving sheet having naturally varying properties, said system comprising:

a computing device having therein program code usable by said computing device, said program code comprising;

code configured to obtain a sheet defect signal during a first sheet making process;

code configured to obtain a first pattern of the naturally varying properties of said moving sheet during said first sheet making process;

code configured to obtain a second pattern of the naturally varying properties of said moving sheet during a second sheet making process; and

code configured to locate said sheet defect during a second sheet making process by correlating said first and said second patterns.

2. The system of claim 1 wherein said first and said second patterns each comprise an optical signature consisting of a continuous measurement of the optical transmission of the moving sheet in one location in the cross-machine direction.

3. The system of claim 1 wherein said first and said second patterns each comprise an optical signature consisting of a 2-D pattern of optical transmission in a predefined cross-machine area.

4. The system of claim 1 wherein said first and said second patterns each comprise a pattern of signal exceptions exceeding a predefined threshold level.

5. The system of claim 1 further comprising code configured to correlate said first pattern to said sheet defect during said first sheet making process to define said sheet defect relative to said first pattern.

6. The system of claim 1 further comprising a machine that performs said first sheet making process.

7. The system of claim 6 further comprising a machine that performs said second sheet making process.

8. The system of claim 1 further comprising a machine that performs said first and said sheet making processes.

11. The method of claim 1 wherein said first and said second patterns each comprise an optical signature consisting of a 2-D pattern of optical transmission in a predefined cross-machine area.

9. A method for tracking features of a moving sheet having naturally varying properties, the method comprising:

detecting a defect in said sheet during a first sheet making process;

obtaining a first pattern of the naturally varying properties of said sheet during said first sheet making process;

obtaining a second pattern of the naturally varying properties of said sheet during a second sheet making process; and

locating said defect during a second sheet making process by correlating said first and said second patterns.

10. The method of claim 9 wherein said first and said second patterns each comprise an optical signature consisting of a continuous measurement of the optical transmission of the moving sheet in one location in the cross-machine direction.

12. The method of claim 9 wherein said first and said second patterns each comprise a pattern of signal exceptions exceeding a predefined threshold level.

13. The method of claim 9 further comprising, correlating said first pattern to said defect during said first sheet making process to define said defect relative to said first pattern.

14. A computer program product for tracking features of a moving sheet having naturally varying properties, said computer program product comprising:

computer usable program code configured to obtain a sheet defect signal during a first sheet making process;

computer usable program code configured to obtain a first pattern of the naturally varying properties of said moving sheet during said first sheet making process;

computer usable program code configured to obtain a second pattern of the naturally varying properties of said moving sheet during a second sheet making process; and

computer usable program code configured to locate said sheet defect during a second sheet making process by correlating said first and said second patterns.

15. The computer program product of claim 14 wherein said first and said second pattern comprises an optical signature consisting of a continuous measurement of the optical transmission of the moving sheet in one location in the cross-machine direction.

16. The computer program product of claim 14 wherein said first and said second pattern comprises an optical signature consisting of a 2-D pattern of optical transmission in a predefined cross-machine area.

17. The computer program product of claim 14 wherein said first and said second pattern comprises a pattern of signal exceptions exceeding a predefined threshold level.

18. The computer program product of claim 14 further comprising computer usable program code configured to correlate said first pattern to said sheet defect during said first sheet making process to define said sheet defect relative to said first pattern.