Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
  • D21F11/006—Making patterned paper
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
  • D21G9/00—Other accessories for paper-making machines
  • D21G9/0009—Paper-making control systems
  • D21G9/0036—Paper-making control systems controlling the press or drying section
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/88—Investigating the presence of flaws or contamination
  • G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/88—Investigating the presence of flaws or contamination
  • G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
  • G01N21/892—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles characterised by the flaw, defect or object feature examined
  • G01N21/898—Irregularities in textured or patterned surfaces, e.g. textiles, wood
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T7/00—Image analysis
  • G06T7/0002—Inspection of images, e.g. flaw detection
  • G06T7/0004—Industrial image inspection
  • G06T7/0006—Industrial image inspection using a design-rule based approach
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/88—Investigating the presence of flaws or contamination
  • G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
  • G01N2021/8887—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges based on image processing techniques
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T2207/00—Indexing scheme for image analysis or image enhancement
  • G06T2207/10—Image acquisition modality
  • G06T2207/10004—Still image; Photographic image
  • G06T2207/10008—Still image; Photographic image from scanner, fax or copier
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T2207/00—Indexing scheme for image analysis or image enhancement
  • G06T2207/20—Special algorithmic details
  • G06T2207/20092—Interactive image processing based on input by user
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T2207/00—Indexing scheme for image analysis or image enhancement
  • G06T2207/30—Subject of image; Context of image processing
  • G06T2207/30108—Industrial image inspection
  • G06T2207/30124—Fabrics; Textile; Paper

Definitions

• three- dimensional shaping is conducted while the papemiaking web is still highly deformab!e, i.e., when the papemiaking web has a high water content.
• this three-dimensional shaping of the web is conducted on a woven structuring fabric,
• the fabric provides a contact surface made up of knuckles in the yams of the fabric, with pockets being formed in the fabric between the knuckles.
• papermaking web is applied to the fabric, portions of the web contact the knuckles, and other portions of the web are drawn into the pockets. Before being removed from the fabric, the web is dried to a point such that its shape is fixed or locked. Domes are thereby formed in the dried web where the web was drawn into the pockets in the fabric, and the domes are present in the finished paper product.
• the paper product has a distinct three-dimensional structure formed, in part, by the knuckle and pocket characteristics of the structuring fabric.
• the contact surface of a structuring fabric directly relates to the shape of the finished product, the choice of a structuring fabric is often based on the shape of the product that is desired, it is difficult, however, to characterize the contact surface of a structuring fabric based on a simple visual inspection of the fabric, While the knuckles of the fabric can easily be seen, it is often difficult to accurately determine the sizes of the knuckles, difficult to determine the areas of the pockets between the knuckles, and difficult to determine the depth of the pockets into which the papermaking web is drawn during the papermaking process.
• my invention provides a process of determining features of a fabric.
• the process includes forming a representation of a portion of a surface of the fabric, the representation showing locations and sizes of knuckles and pockets in the surface of the fabric, generating an image of the portion of the surface of the fabric based on the representation, displaying at least a portion of the image on a screen associated with a computer having a processor, and drawing an outline around at least one of the knuckles displayed image.
• the process further includes drawing guidelines in the displayed image such that the guidelines (i) pass through the center of the outlined knuckle, (ii) pass through the other knuckles, (iii) form a shape that surrounds areas of the image that correspond to where the pockets are formed between the knuckles.
• the outline and guidelines are drawn using an image analysis program stored in a non-transitory computer-readable medium.
• the process includes forming a representation of a portion of a surface of the fabric, with the representation showing locations and sizes of knuckles and pockets in the surface of the fabric, and the representation being one of a print of the fabric surface and a photograph of the surface of the fabric,
• the process further includes generating an image of the portion of the surface of the fabric based on the representation, displaying at least a portion of the image on a screen associated with a computer having a processor, determining the sizes and locations of the knuckles in the display of the representation, and determining the sizes and locations of the pockets in the display of the representation.
• the process also includes drawing a unit cell for the portion of the surface of the fabric in the displayed image, wherein the unit cell is defined by guidelines that (i) pass through the centers of the knuckles and (ii) form shapes that surround areas of the image that correspond to where the pockets are formed between the knuckles. At least one property of the surface of the fabric is calculated based on properties of the unit cell formed by the guidelines, and the outline and guidelines are drawn using an image analysis program stored in a non-transitory computer-readable medium.
• FIGS. 6 A through 6E show the steps of establishing a coordinate system for the structuring fabric print.
• FIGS. 7 A, 7B, and 7C show the application of the analytic technique herein applied to a photograph of the knuckles of a fabric.
• FIGS. 8A and 8B show an alternative analytic technique applied to a photograph and print of the knuckles of a fabric
• FIG . 9 shows the application of the analytic technique to determine a pocket surrounded by knuckles in a structuring fabric
• FIGS, 1 1 A and 1 IB show the application of the analytic techniques applied to an image of a paper product and its structuring fabric.
• My invention relates to apparatuses, processes, and systems for determining the characteristics of the contact surface of a fabric that is used in a papermaking process.
• characteristics of the contact surface of a fabric refers to the characteristics of the contact surface that result from the knuckle and pocket configuration that makes up the contact surface of the fabric.
• my invention is adapted for use with structuring fabrics that are used for three-dimensional structuring of a web in a papermaking process.
• FIG. 1 shows an example of a through air drying (TAD) papermaking process in which a structuring fabric 48 is used to form the three-dimensional structure of the paper product.
• TAD through air drying
• furnish supplied through a head box 20 is directed in a jet into the nip fomied between a forming fabric 24 and a transfer fabric 28.
• the forming fabric 24 and the transfer fabric pass between a forming roll 32 and a breast roll 36,
• the forming fabric 24 and transfer fabric 28 diverge after passing between forming roil 32 and breast roll 36.
• the transfer fabric 28 then passes through dewatering zone 40 in which suction boxes 44 remove moisture from the web and transfer fabric 28, thereby increasing the consistency of the web, for example, from about 10% to about 25% prior to transfer of the web to structuring fabric 48.
• vacuum assist boxes 52 it will, be advantageous to apply some amount of vacuum as indicated through vacuum assist boxes 52, in a transfer zone 56, particularly, when a considerable amount of fabric crepe is imparted to the web in transfer zone 56 by a rush transfer wherein the transfer fabric 28 is moving faster than the structuring fabric 48.
• the web is transferred from the structuring fabric 48 to the Yankee cylinder 68 without a major degradation of its properties by contacting the web with adhesive sprayed onto Yankee cylinder 68 just prior to contact with the translating web. After the web reaches a consistency of at least about 96%, light creping is used to dislodge the web from Yankee cylinder 68.
• Whi le Figure 1 demonstrates one type of process in which a structuring fabric is used to impart a three-dimensional shape to a paper product
• a structuring fabric may be used in a papennaking process that does not utilize through air drying (TAD).
• TAD through air drying
• An example of such a non-TAD process is disclosed in U.S. Patent No. 7,494,563, the disclosure of which is incorporated by reference in its entirety.
• the invention disclosed herein is not limited to being used in any particular papermaking process, but rather, may be applied to fabrics used in a wide variety of papennaking processes.
• Figure 2 is a view of a portion of the web facing side of a structuring fabric 200.
• the fabric 200 includes warp yarns 202 that would run in the machine direction (MD) when the fabric 200 is used in a papennaking process, and weft yarns 204 that run in the cross machine direction (CD) when the fabric 200 is used in a papermaking process.
• the warp and weft yams 202 and 204 are woven together so as to form the structure of fabric 200. It should be noted that, when looking down on Figure 2, in the web-contacting surface of the structuring fabric 200, some of the depicted yarns 202 and 204 are below the plane that contacts the web during the papennaking process, i.e., the contact surface of the fabric 200.
• the upper-most points of the yams 202 and 204 that define the plane of the contact surface are the knuckles 206 and 208. That is, the knuckles 206 and 208 form the actual contact surface of the forming fabric 200.
• Pockets 210 (shown as the outlined areas in Figure 2) are defined in the areas between knuckles 206 and 208.
• portions of the web can be drawn into the pockets 210, and it is the portions of the web that are drawn into the pockets 210 that correspond to the domes in the finished paper product, as also described above.
• a structuring fabric may not initially be manufactured with knuckles, such as the knuckles 206 and 208 in Figure 2.
• knuckles are often formed by sanding or grinding one of the surfaces of the structuring fabric. Further, as the structuring fabric is used in a papermaking operation, wear on the surface of the structuring fabric may further increase the length of the knuckles. As will be described below, the present invention provides for determining characteristics of the knuckles, including characteristics of the knuckles as the fabric is subjected to wearing. It should also be noted that a structuring fabric can take on numerous forms, depending on, for example, the weave pattern of the warp and weft yarns and the size of the yams.
• the structuring fabric 200 depicted in Figure 2 includes knuckles 206 that are formed on the warp yams 202 and knuckles 208 that are formed on the weft yarns 204. This may have resulted from the fabric 200 being sanded or worn to the point that the knuckles are formed on both the warp and weft yams 202 and 204, With less sanding, however, the fabric 200 might have only knuckles 206 on the warp yarns 202, and not on knuckles 208 on weft yarns 204, or vice versa.
• FIG. 3 A An apparatus and a technique for forming a print of the contact surface formed by the knuckles of a fabric is shown in Figures 3 A and 3B
• Figure 3 A is a side view of a contact surface printing apparatus 300
• Figure 3B is a front view of the contact surface printing apparatus 300.
• This apparatus 300 includes a C-shaped frame structure 302 with first and second arms 303 and 305.
• a first plate 304 is movably supported by the first arm 303, and a stationary second plate 306 is supported by the second arm 305.
• a print of the knuckles of a fabric is formed between the first and second plates 304 and 306, as will be described in detail below.
• the first plate 304 is operatively connected to a hydraulic pump 308 for actuating movement of the first plate 304 towards the second plate 306. in some
• hydraulic pump 308 is hand-operated, with a release valve for allowing the first plate 304 to be retracted from the second plate 306.
• the pump 308, however, can take many other forms so as to effect movement of the first plate 304.
• the pump 308 may be connected to a transducer and transducer indicator 310 for measuring the pressure applied by the pump 308 to the first plate 304 as the first plate 304 is pressed against the second plate 306.
• a transducer and transducer indicator 310 for measuring the pressure applied by the pump 308 to the first plate 304 as the first plate 304 is pressed against the second plate 306.
• the pump 308 and transducer and transducer indicator 310 may be combined into a single unit.
• the frame 302 of the contact surface printing apparatus 300 includes wheels 312 adjacent to the front end of the frame 302, as well as a mount 313 that may be used to hold the pump 308 and/or transducer 310.
• One or more wheels provided to the frame 312 make the frame 302 easier to move.
• An advantageous feature of the contact surface printing apparatus 300, according to embodiments of the invention, is lis portability. For example, with a configuration as shown m Figures 3A and 3B, the print apparatus 300 may be easily moved about sections of a fabric that is mounted on a papermaking machine.
• the ability to form prints of the contact surface of a fabric while the fabric is mounted to a papermaking machine, and, thus, characterize the fabric according to the techniques described below, provides numerous benefits.
• the wearing of a fabric on a papermaking machine can easily be monitored by using the contact surface printing apparatus 300 so to take prints of the knuckles of the fabric after different periods of operation of the papermaking machine,
• the contact surface printing apparatus 300 shown in Figures 3A and 3B includes a frame structure 302 that connects the first and second plates 304 and 306, in other embodiments, a contact surface printing apparatus may not include such a single frame structure 302. instead, the first and second plates 304 and 306 may be non-connected structures that are individually aligned to form the print of a fabric. In still other embodiments, the plates 304 and 306 may take vastly different forms from those depicted in Figures 3A and 3B. For example, one of the plates 304 and 306 could be formed as an extended surface, while the other plate is formed as a circular structure that is rolled across the extended surface.
• FIG. 4 is a detai led view of Section A of the contact surface printing apparatus 300 shown in Figure 3 A, with the apparatus 300 being set up to make a print of a section of a fabric 312.
• the fabric 312 is positioned between the plates 304 and 306, and a strip of pressure measurement film 314 is positioned against the structuring fabric 312.
• Between the pressure measurement film 314 and the first plate 304 is one or more sheets of paper 316.
• Between the fabric 312 and the second plate 306 is a strip of rubber 318.
• Pressure measurement film is a material that is structured such that the application of force upon the film causes microcapsules in the film to rapture, producing an instantaneous and permanent, high-resolution image in the contacted area of the film.
• An example of such a pressure measurement film is sold as Prescale film by Fujifilm Holdings Corporation of Tokyo. Japan.
• Another example of pressure measurement film is PRESSUREX-MICRO® by Sensor Products, Inc., of Madison, New Jersey.
• the simulated pressure would be the pressure that is applied to the web against the fabric 48 to the Yankee cylinder 68.
• the pressure applied to the web against the fabric is generally in the range of six hundred psi. Accordingly, to simulate this papermaking process, six hundred psi of pressure would be applied by the hydraulic pump 308 to the plate 304 when forming the image of the knuckles of fabric 312 in the pressure measurement film 314. For such an operation, it has been found that medium pressure 10-50 MPa Preseaie film by FujiFiim can provide a good image of the knuckles of a structuring fabric.
• the paper 316 acts as a cushion to improve the print of the fabric 312 formed on the pressure measurement film 314. That is, paper 316 provides compressibility and a smooth surface, such that the knuckles of the fabric 312 may "sink" into the pressure measurement film 314, which, in turn, forms a high resolution image of the knuckles in the film 314, To provide these properties, construction and kraft are examples of types of paper that could be used for the paper 316.
• the strip of rubber 318 creates a level contact surface for supporting the fabric 314.
• the plates 304 and 306 are made of a metallic material, such as steel. A steel plate would most likely have imperfections that reduce the quality of the print of the knuckles of the fabric formed in the pressure measurement paper 316.
• a print is made of the knuckles of a fabric in materials other than pressure measurement film.
• a material that can be used to form prints of a film is wax paper.
• a print of the contact surface of a fabric may be made in a wax surface by pressing the contact surface of a fabric against wax paper.
• the print in the wax paper could be made using the plates 304 and 306 in the print forming apparatus 300 described above, or with other configurations of the plates.
• the wax paper print can then be analyzed in the same manner as a pressure measurement film print, as will be described below.
• Figures 5 A through 5D show examples of prints of knuckles formed in pressure measurement film using the contact surface printing apparatus 300.
• Such a computer system will include well-known components, such as at least one compuier processor (e.g., a central processing unit or a multiple processing unit) that is connected to a communication infrastructure (e.g., a communications bus, a cross-over bar device, or a network),
• a further component of the computer system is a display interface (or other output interface) that forwards video graphics, text, etc, for display on a display screen
• the computer system may still further include such common components as a keyboard, a mouse device, a main memory, a hard disk drive, a removable-storage drive, a network interface, etc.
• a print of the contact area of the knuckles of a fabric is converted to a computer readable image using a photoscanner.
• Any type of photoscanrier may be used to generate the computer readable image. In certain embodiments, however, a photoscanner having at least 2400 dpi has been found to provide a good image for analysis.
• an imaging analysis program (as will be described below) can apply an exact scale to the image, As will be described below, the exact scaling will be used in the calculation of the surface characteristics of the structuring fabric.
• the scanned image may be stored in a non-transitory computer-readable medium in order to facilitate the analysis described below.
• a non-transitory computer readable medium as used herein, comprises all computer-readable media except for a transitory, propagating signal. Examples of non-transitory computer readable media include, for example, a hard disk drive and/or a removable storage drive,
• the scanned image, as well as characteristics of the contact surface scanned image that are determined according to the techniques described below, may be associated with a database.
• a “database,” as used herein, means a collection of data organized in such a way that a computer program may quickly select desired pieces of the data, e.g., an electronic filing system.
• the term “database” may be used as shorthand for "database management system,”
• an image analysis program is used with the scanned images of the knuckles of a fabric.
• Such an image analysis program is developed, for example, with computational software that works with graphical images.
• computational development software is MATHMATICA® by Wolfram Research. LLC, of Champaign, Illinois.
• the image analysis program will be used to specifically identify the knuckles in the fabric print image of the structuring fabric, and, with known scaling of the fabric print linage, the image analysis program can calculate the sizes of the knuckles and estimate sizes of the pockets.
• any size area that includes a plurality of knuckles and a pocket could be used for the analysis described below, in specific embodiments, it has been found that a 1 ,25 inch by 1.25 inch area of an image of a fabric allows for a good estimation of properties, such as pocket sizes using the techniques described herein, in particular, it has been found that when an image is formed with a 2400 dpi resolution (discussed above), and using a 1.25 inch by 1.25 inch area of an image for the analysis, a good characterization of the contact surface can be conducted. Of course, other resolutions and/or area may also provide good results.
• Figure 6 A through 6E depict the steps of identifying the knuckles in a magnified portion of the scanned image of a print using the image analysis program.
• a magnified portion of an image 600 is viewed on the display screen of the computer system running the analysis program.
• the image 602 which may be formed using the print technique described above, shows the knuckles 602.
• Hie scaling of the image 600 can be input into an analysis program. Such a scaling may be input, for example, as 2400 dpi, from which the analysis program can apply the scale SC to the image 600.
• the analysis program will then use the scale to calculate the sizes and positions of the knuckles, as described below.
• Figures 6B and 6C shows steps for identifying a specific knuckle 602A using the analysis program.
• the knuckle 602 A is initially selected based on its location at a center region of the magnified image 600. in this step, a rough outline of the knuckle 602A is applied.
• the rectangular box 604, which may be a stored shape in the analysis program, is initially applied around the knuckle 602A in order to initiate the knuckle identification process.
• the initial rectangular box 604 shape may then be more closely refined to match the shape of the knuckle 602 A, as shown in Figure 6C,
• the ends 606 and 608 are reshaped to be more rounded, and, thus, more closely correspond to the ends of the knuckle 602 A,
• further refinements could be made to the outline of the knuckle 602A until a sufficient match is made. Such refinements might be conducted by further magnifying the image 600.
• guidelines 610 and 612 are drawn.
• the guidelines 610 and 612 are each drawn so as to pass through the center of the knuckle 602 A, and extend in straight lines through the centers of the other knuckles.
• the guidelines 610 and 612 are also drawn so as to not cross the areas where pockets are formed in the fabric, which are known to correspond to the areas between groups of knuckles.
• the guidelines 610 and 612 do not cross the area of the pockets that are formed between the knuckles.
• guidelines 610 and 612 are drawn, as shown in Figure 6E, further guidelines axe drawn. These guidelines are drawn in a similar manner to guidelines 610 and 612, i.e., through the centers of the knuckles and not passing through areas where pockets are formed. To aid in the process of drawing the guidelines, a lower magnification may be used. With the guidelines, a coordinate system is, in effect, established for the positions of the knuckles. The analysis program, therefore, can now identify the size and shape of the knuckles based on the outline 602A, and can identify the locations of the knuckles as determined by the points wherein the guidelines cross. The analysi s program further has the scale SC of the image 600 input.
• the analysis program can apply the scale to the outline knuckle 602 A and the knuckle positioning to calculate the actual sizes and spacing of the knuckles.
• the analysis program may calculate the frequency of the guidelines such as the number of times that the guidelines 612 cross guideline 610 per a unit length. The frequency of each set of the guidelines 610 and 612 will be used in calculations of properties of the fabric, and in other aspects of the in venti on, as will be described below.
• the guidelines 610 and 612 define a plurality of unit cells, A particular unit cell 613 is shown between guideline segments 610A, 610B, 612A, and 6 ⁇ 2 ⁇ ,
• the unit cell 613 in effect, demonstrates the minimum repeating pattern in the fabric, and the maximum allowable pocket size, It should be noted while the fabric shown in Figures 6 A through 6E has about one warp knuckle per unit cell, other fabrics may have more than one warp knuckle and/or more than one weft knuckle per unit cell, in other words, the unit cells defined by knuckle patterns will vary with different fabric patterns.
• any or all of the steps shown in Figures 6A through 6E can either be performed by a user on a display screen, or alternatively, may be automated so as to be performed upon execution of the analysis program. That is, the analysis program may be configured to automatically identify knuckles as the darkened regions of images, outline the knuckles, and then draw the guidelines based on the identified knuckles in the mariner described above.
• the knuckle size and positioning data can be exported from the analysis program to a conventional spreadsheet program to calculate the properties of the fabric. Examples of the determinations made by the analysis program and the calculations that follow from such determinations arc shown in Table 1.
• the fabric from which image 600 was obtained only included knuckles 602 on the warp threads.
• Other fabrics may include knuckles on the weft threads, such as the fabrics thai formed the prints in Figures 533 and 5D. With such fabrics, the knuckles on the weft threads can be identified using the outlining technique described above, and the guidelines can be drawn through the weft knuckles using the technique described above.
• the contact surface of a fabric may be characterized by using a print of the knuckles of the fabric that is formed, for example, by the contact surface printing apparatus 300
• an image of the contact surface of the fabric may be obtained in a different manner.
• An alternative to forming a print of the knuckles of the fabric is to photograph the knuckles of a fabric, and then use the above-described procedures and techniques for analyzing an image formed from the photograph. In this regard, a photograph with 2400 dpi has been found to provide sufficient high and low resolution so as to be analyzed by the techniques described herein.
• FIG. 7A An example of a photograph 700 of the portion of a papermaking fabric with knuckles 702a is shown in Figure 7A, and the application of the above-described analytic technique to the image generated from photograph 700 is shown in Figures 7B and 7C.
• the photograph 700 in Figure 7A shows the fabric 701 next to a ruler R.
• the scale for the image 700A can be input based on the photographed ruler R. That is, ruler R in the image 700A provides an input from which the analysis can apply a scale to the image.
• the displayed image 700A, along with the scale SC, is shown in Figure 7B.
• Table 2 shows the results of the calculations of surface characteristics for a fabric, with one set of calculations being derived from a print of the fabric, and a second set calculations being derived from a photograph of the fabric.
• FIG. 8A is an image generated from a photograph of the surface of a fabric using the above described image analysis program.
• a unit cell 813 is defined by the guideline segments 810A, 810B, 812A, and 812B.
• the unit cell 813 formed by the guideline segments 810A, 810B, 812A, and 812B is a substantially non-rectangular, parallelogram shape.
• an angle ⁇ is defined at the corner A where guideline segments 810 A and 812B intersect, and the angle ⁇ is also defined at the corner B where the guideline segments 81 OB and 812A intersect.
• This angle ⁇ can be readily determined using the image analysis program based on the difference in orientation angles of the guidelines. Further, the image analysis program can also determine the distance between the guideline segments 81 OA and 810B ("DIST 1") and the distance between guideline segments 812A and 812B (“DIST 2") based on the scale of the image in the manner generally described above. Having determined the intersecting angle ⁇ , the DIST 1, and the DIST 2, the area of the unit cell (UCA) can be calculated using either of the Formula ( 1 ) or Formula (2):
• Table 3 shows examples of determinations made by the analysis program and the calculations that follow from such determinations when using the alternative technique based on a non-rectangular, parallelogram unit cell area calculation.
• KL Knuckle Length
• Knuckle Width determined based on outline of identified warp knuckle or identified weft knuckle
• freq 1 frequency of the first set of parallel lines (per inch or cm)
• freq 2 frequency of the second set of parallel lines (per inch or cm)
• the knuckle density, the total warp or weft knuckle contact area, the contact area ratio, the percent area contribution, the pocket area estimate, and the pocket density characteristics are calculated differently in TABLE 3 than in TABLE 1 .
• these different calculations provide for more accurate estimations of the characteri sti cs of fabrics that have non- rectangular, parallelogram shaped unit cells.
• Figure 8B is a print of a fabric made with the above-described techniques, in this case, the fabric has very non-rectangular unit cells, with one of the angles ⁇ at the corners of the parallelograms defining the unit cells being about 140 degrees.
• two sets of calculations were performed on the fabric, with the results being shown in TABLE 4.
• a papermaking fabric Another important characteristic of a papermaking fabric is the depth to which the web can be drawn into pockets in the fabric during the papermaking process, As discussed above, domes are formed in final paper products that correspond to the portions of the web that were drawn into the pockets in the fabric. Hence, the pocket depth of a papermaking fabric directly affects the paper product formed using the fabric. Techniques for determining the pocket depth of a fabric will now be described,
• the pocket depth of a structuring fabric is determined as the depth in the pocket to which the cellulosic fibers could penetrate in the paper making process.
• the maximum fiber migration depth is at the center of the pocket.
• a profile direction line could alternatively be drawn from knuckle K2 to knuckle K4 passing through the center of the pocket, and the alternative profile direction line could be used for the pocket depth determination described below.
• different structuring fabrics will have different configurations of knuckles and pockets, but a profile direction line could easily be determined for different structuring fabrics in the same manner as the profile direction line is determined as shown in Figure 9.
• Figure 10 is screenshot of a program used to determine the profile of a pocket of the structuring fabric shown in Figure 9.
• the screenshot was formed using a VHX-1000 Digital Microscope manufactured by Keyence Corporation of Osaka, Japan.
• the microscope was equipped with VHX-H3M application software, also provided by Keyence Corporation.
• the microscopic image of the pocket is shown in the top portion of Figure 10. In this image, the knuckles K' 1 and K'3 and the pocket between the knuckles can easily be seen.
• a depth determination line DL has been drawn from point D to point C, with the depth determination line DL passing through the knuckles K*l and K'3 and through the center of the pocket.
• the depth determination line DL is drawn to closely approximate the profile determination line PL that is shown in Figure 8. That is, based on inspection of the depth determination line DL derived using the knuckle and pocket image shown in Figure 9, a user can draw the depth determination line DL in the microscopic image shown in Figure 10, with the depth determination line DL passing through the areas that correspond to the knuckles K'3 and K' 1 and the center portion of the pocket.
• the digital microscope can then be instructed to calculate the depth profile of the pocket along the depth determination line DL, as is shown in the bottom portion of Figure 10.
• the profile of the pocket is highest at the areas corresponding to the knuckles K'3 and K' 1 , and the profile falls to its lowest point at the center of the pocket.
• the pocket depth is determined from this profile as starting from the height of the knuckles K'3 and K'l, which is marked by the line A on the depth profile.
• the knuckles K'3 and K' 1 do not have the exact same height.
• each of the alternative depth measurement instruments i.e., digital microscope, laser profiler, or laser line scanner
• a digital microscope might provide a highly precise measurement of pocket depth.
• a laser profiler is generally an easy instrument to work with, and thereby can provide a quick measurement of pocket depth.
• a laser line scanner has the ability to quickly collect large volumes of data, and, thus, measure many depth profiles in a short period of time.
• an embodiment of my invention includes using a laser line scanner to determine pocket depth profiles of a structuring fabric that is running on a papermaking machine.
• the measured pocket depth will slightly vary from pocket to pocket in a fabric. I have found that, generally speaking, an average of five measured pocket depths for a structuring fabric provides a good characterization of the pocket depth. Of course, more or fewer measure measurements can be performed to determine an average pocket depth depending, for example, on the level of accuracy desired in the measurement.
• a representation of the knuckle and pocket structure of a fabric can be formed by pressing the contact surface of a fabric against wax paper, as is also described above.
• the wax representation of the fabric can then be scanned using one of the above-described techniques.
• a laser line scanner can be used to determine the depth in the wax print between the knuckles in the wax print.
• the effective volume of a pocket is the product of the cross- sectional area of the pocket at the surface of the structuring fabric (i.e., between the knuckle surfaces) multiplied by the depth of the pocket into which cellulosic fibers in the web can migrate during the papermaking process.
• the cross-sectional area of the pockets is the same as the estimate of the pocket area (PA), as described in TABLE 1 or TABLE 2 above.
• PA pocket area
• Another important property of a structuring fabric may be defined as a planar volumetric index for the fabric.
• characteristics of the knuckles and pockets of a fabric such as knuckle and pocket sizes and densities
• One example of the application using the characteristics involves developing correlations between certain contact surface characteristics and resulting paper products. With the correlations, further fabric configurations can be developed, and those configurations can be characterized without testing a full-scale fabric on a papermaking machine.
• the techniques described above for determining contact surface characteristics of a fabric may save time and resources for both fabric manufacturers and/or paper producers that are experimenting with different fabrics.
• a first representation of the knuckles in a portion of the fabric is formed in a medium.
• This first representation may be a print on a pressure measurement film, or the representation may be a photograph of a portion of the fabric and stored in a camera.
• a first image is generated of the knuckles of the fabric based on the first representation, such as by scanning the pressure measurement film or downloading the photograph from the camera. From the generated image, at least one characteristic related to the contact area of the fabric may be determined as described above.
• the fabric may then be subjected to wearing. If the fabric is mounted on a papermaking machine, the wearing may come about simply by operating the papermaking machine. Alternatively, a simulated wearing may be performed on the fabric by sanding or grinding.
• the process of obtaining an image of a portion of the fabric and determining contact surface characteristics is again performed. That is, a second representation of the knuckles in the portion of the fabric is formed in a medium, which is used to generate a second image, which in turn is analyzed to determine the surface characteristics of the film.
• the second representation may or may not be taken from the same portion of the fabric as the first representation. It would be expected that knuckles in the fabric would increase in size as a result of the wearing. Further, new knuckles may be formed in the fabric.
• increases in the knuckle sizes can be quantified by comparing the analysis of the second image after wearing and the first image before wearing. Such a process of wearing the fabric and thereafter determining the contact surface characteristics may be repeated any number of times, and with any given amount of wearing between each analysis.
• the above-described techniques and processes may be used to compare different portions of a fabric, particularly, after the fabric runs on a papermaking machine over periods of time. It is known that different portions of a fabric will often show different wearing due to inconsistencies in the track that the fabric follows in the papermaking machine.
• the surface characterization techniques can be applied, for example, to different portions of a fabric before and after the fabric is run on a papermaking machine. Alternatively, the surface characterization techniques can be applied to different portions of the fabric while the fabric is still mounted on the papermaking machine. Thus, an understanding can be achieved of how different portions of a fabric are worn in a papetmaking machine.
• an outline 802 A can be drawn on the image of the paper product using the analysis program in a land area of the paper product, which corresponds to the position of a knuckle in the structuring fabric used to make the paper product. Further, a coordinate system including guidelines 812 and 814 can be drawn through the outline 802 A, and the positions that correspond to other knuckles. Note that the domes in the paper product correspond to the pockets in the structuring fabric, and accordingly, the coordinate system is drawn without passing through the domes.
• the outline 802A and coordinate system may he matched to images of fabrics so as to determine a configuration that produces the three-dimensional structure of the paper product.
• An example of such a match is shown in Figure 11B, wherein the outline 802 A of and coordinate system with guidelines 812 and 814 are overlaid upon an image 800 A of a fabric.
• the outline 802A matches the size and shape of a knuckle in the fabric, and that the guidelines pass through the knuckles, but not the areas that correspond to pockets in the fabric, This matching indicates that the fabric shown in image 800A could be used to produce a paper product similar to that shown in image 800.
• Matching the outline and coordinate system from a paper product to a particular fabric may be facilitated by creating a searchable database of known fabrics.
• a database would include the previously-determined contact surface characteristics of fabrics, such the knuckle sizes, locations, pocket sizes, etc. After determining the sizes and positions for the knuckles and pockets of the fabric from the outline and coordinate system formed from the paper product, the database could be searched for fabrics with similar sizes and positions of knuckles and pockets.
• additional parameters may be used that are developed in the analysis of the paper product.
• One such additional parameter is the frequency that one set of guidelines crosses a guideline from the other set of guidelines.
• a "set" of guidelines refers to parallel guidelines, e.g., the guideline 812 and all the guidelines parallel thereto to form a set.
• the frequency of the set of guidelines that includes guideline 812 would be calculated, for example, having the analysis program determining the distance between two of the guidelines crossing guideline 810, as measured along one guideline 810.
• the crossing guidelines would have a frequency of 7.7 cm '1 (1/0.130 cm).
• a similar frequency calculation could be done for the other set of guidelines that cross guideline 812 by measuring the spacing between the guidelines of this set along one of the guidelines 812. Once determined, the frequency in the guideline spacing for a paper product could be matched to the previously determined frequency of guideline spacing for fabrics, which have been stored in a searchable database.
• Another parameter that can be calculated to facilitate the process of matching the outlined knuckle and guidelines from a paper product to a particular fabric is the angle to the guidelines of a set from a reference line.
• the scale line SC in Figure 11 A could be used as a reference, and the angle a could be determined between the scale line SC and one set of the guidelines.
• the angle from the scale line SC to the other set of guidelines could also be determined.
• the angles from the reference to the sets of guidelines for a paper product could be matched to the previously determined angles from the reference to the sets of guidelines for fabrics, which have been stored in a searchable database.
• a fabric could be designed and manufactured based on the analysis of a paper product image or based on a created image representing a knuckle and pocket configuration.
• warp and weft yarns are chosen to correspond to the desired knuckle and pocket configuration, as determined by analysis of the paper product image or created in a blank image.
• Techniques for producing fabrics with particular weave patterns of warp and weft yarns are well known in the art.
• a fabric could be produced with the chosen warp and weft yarn configuration.
• the fabric characterization techniques described herein can be used to modify the configuration of a first papermaking fabric in order to produce a new, second papermaking fabric having different characteristics.
• at least one knuckle or pocket characteristic of the first papermaking fabric is determined with the above-described techniques.
• the characteristic may be, for example, one or more of the characteristics described in TABLE 1 or TABLE 2 above.
• the characteristic may be the pocket depth or effective pocket volume, which are determined according to the above-described techniques. Based on the determined characteristic(s), a modified fabric design is created wherein the characteristics) are changed. For example, the pocket depth may be increased from the pocket depth measured in the first papermaking fabric.
• the characteristics of paper products made using the structuring fabrics can be used in the development of a papermaking fabric having particular characteristics.
• the characteristics of a first papermaking fabric can be determined using the above-described techniques.
• the first papermaking fabric can also be used to make a papermaking product, for example, using the papermaking methods described above.
• the characteristics of the paper product can then be determined, and thereafter correlated with the determined characteristics of the first papermaking fabric. For example, the densities and heights of the domes formed in the paper product can be measured by examining the domes with a microscope.

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