Apparatus and method for measuring roll sidewall quality
An apparatus for measuring a sidewall characteristic of a wound roll includes a housing, a platform mounted in the housing having a surface adapted to receive the wound roll, a distance measuring sensor supported in the housing for movement along a predetermined line of measurement extending across at least a portion of the sidewall of the wound roll for measuring the sidewall characteristic, and a processor for processing the sidewall characteristic and generating at least one quality metric representative of the quality of the roll.
The invention relates to manufacturing a roll of material, such as photographic paper, and more particularly, to an apparatus and method for determining the roll quality of a wound roll of material.
BACKGROUND OF THE INVENTIONPaper and other materials are manufactured using a continuous process that produces a traveling web of material. The web is wound in a roll of a specific size for further processing or distribution. Variables in the manufacturing process can affect the aesthetic appearance of the roll. For example, improperly controlled web tension during winding can cause conveyance weave and air entrapment between the winding layers, which can cause poor sidewall quality. Uneven web caliper (i.e., thickness) from one side of the web to the other can cause dishing wherein the edges of the roll lie in a different plane than the center, like a dish. Also, as the web travels over rollers, imperfections in the web or rollers or temperature fluctuations can cause the edges of the web to be uneven so that all individual windings do not lie in the same plane. These defects give the appearance that the roll quality is poor. Poor sidewall can cause functional failures during conveyance in printers; but without a tool to quantify sidewall profile and maximum roll width, the evaluation of roll quality in the factory can be subjective and unnecessary waste may be taken when acceptable rolls are rejected and discarded. There thus is a need to have a quality standard and a quantitative method and apparatus for measuring roll sidewall quality to provide both functionally and visually acceptable rolls.
Some paper or other material typically leaves the manufacturing facility as rolls that are to be photographically printed and cut to sheets of desired dimensions. A roll that is not perfectly wound may require extra effort to print and cut to desired dimensions, and may cause jams/stops in photo-processing equipment. Such rolls require careful monitoring as sheets are cut to ensure uniformity which translates to higher machinery costs and/or higher processing costs which is undesirable. A need therefore also exists for a method of quantifying roll sidewall quality and comparing to existing specifications for width in order to reduce extra processing costs.
SUMMARY OF THE INVENTIONThe present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the present invention, an apparatus for measuring a sidewall characteristic of a wound roll, where the wound roll comprises a strip of material wound about an axis, thereby forming a wound roll having concentric windings parallel to the axis with upstanding sidewall edges extending radially from the axis, includes a housing, a platform mounted in the housing having a surface adapted to receive the wound roll, a distance measuring sensor supported in the housing for movement along a predetermined line of measurement extending across at least a portion of a sidewall of the wound roll for measuring the sidewall characteristic, and a processor for processing the sidewall characteristic and generating at least one quality metric representative of the quality of the roll.
According to another aspect of the present invention, a method for measuring sidewall quality of a wound roll comprises the steps of positioning the wound roll on a planar surface with the axis perpendicular to the planar surface and with one edge of the sidewall exposed in an upstanding position, positioning a distance measuring sensor above the sidewall for movement along a predetermined line of measurement extending across at least a portion of the sidewall of the wound roll, moving the distance measuring sensor along the line of measurement and generating a plurality of data points, and processing the data points to generate at least one quality metric representative of the quality of the roll.
The wound roll has a width determined from the surface of the platform to one or more of the upstanding sidewall edges and the data points measured by the distance measuring sensor comprise distance data taken along the line of measurement. This distance data corresponds to the distance of the upstanding edges of the sidewall windings from the platform surface.
In another aspect of the invention, a quality metric is derived from a profile of the width dimension as seen from the sidewall of the wound roll. For example, the quality metric comprises a maximum roll width quality metric based on the profile of the width dimension of the sidewall. In yet another aspect of the invention, the quality metric correlates roll quality with the visual appearance of the sidewall. In particular, the metric involves determining shadowed data points by the presence of shadow areas comprising data points that are shadowed if the sidewall were to be illuminated by light of low incident angle, and accumulating shadowed data points and determining a length of the shadow areas. The quality metric is a shadow quality metric that is obtained by determining the ratio of ((total number of data points)−(the number of data points comprising shadow areas each greater than a predetermined length)/(total number of data points)).
In particular, defining an appearance metric as the ratio of the width of lighted edges in the radial direction to the total radial width of the wound roll provides a metric with special advantage for measuring roll sidewall quality. Counting only shadowed edges having a length greater than about 1.5 mm in the radial direction provides a useful, quantitative metric for gauging the quality of a roll of photographic paper.
These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Because surface measurement techniques employing laser or like devices and related circuitry are well known, the present description will be directed in particular to elements forming part of, or cooperating more directly with, apparatus and method in accordance with the present invention. Elements not specifically shown or described herein may be selected from those known in the art. Certain aspects of the embodiments to be described may be provided in software. Given the apparatus and method as shown and described according to the invention in the following materials, software not specifically shown, described or suggested herein that is useful for implementation of the invention is conventional and within the ordinary skill in such arts.
Referring to
The distance measuring sensor 17 used in the preferred embodiment of the invention is a Model AR600-1 Laser Displacement Sensor from Acuity Research. The AR600-1 sensor is a laser diode based distance measurement sensor that uses triangulation to measure distance. The laser beam is projected from the housing of the sensor 17 and is reflected from the sidewall surface to a collection lens. The lens focuses an image of the spot on a linear array camera (not shown) within the housing of the sensor 17. The camera views the measurement range from an angle that varies from 45 to 65 degrees at the center of the measurement range. The position of the spot image on the pixels of the camera is then processed to determine the distance to the sidewall 13. The AR600-1 sensor has a measuring distance of 2.5 inches and measures distances over its full scale span with an accuracy of 0.001 inches. This means, referring to
Referring now to
A bottom panel is connected to the left and right frame members 24, 26 forming a platform 30. Platform 30 has a rigid planar surface for receiving wound roll 12. Roll position stops 32, 34 in housing 22 adjacent platform 30 are arranged in a V-shape. An ultrasonic sensor 36 is arranged near the vertex of the V-shaped stops 32, 34. As shown in
Referring to
While
As shown in
In the preferred embodiment, the sidewall gauge is capable of measuring the maximum width and profile of one half of the sidewall, from an outer lap to the core 11, on a roll of photographic paper. Roll widths, for example, from 3.25 to 14 inches and diameters from 4.5 to 18 inches can be measured by the distance measuring sensor 17. Obviously, the gauge can be modified to handle other widths and diameters. The gauge was designed for non-destructive measurements and, although the gauge housing is not itself light tight in the preferred embodiment, it can be used in both dark and light environments. More specifically, the gauge uses the touch screen monitor 44 for operation in the dark but can also utilize a typical large screen monitor 20, mouse and keyboard while in a lighted condition. Referring now to
In the monitor selection step 102, either the touch screen monitor 44 or the large screen computer monitor 20 is selected. The touch screen monitor 44 is to be used in the dark and the large screen monitor 20 can be used in white light. In the roll preparation step 104, the roll 12 is manually prepared for placement in the sidewall quality gauge. In white light conditions, the operator should visually inspect the roll 12 for any singular or nearly single lap protrusions or “stick-outs” in the sidewall of the roll. If only one side has such protruding laps, it is this side that should be placed facing upward on the platform 30 so as to be “seen” by the laser beam 18 of the distance measuring sensor 17. In a dark environment, the operator is limited to what can be felt of these protruding laps. After the roll is placed on the platform 30, whether in white light or in the dark, the operator should push downward on the outer laps, all around the roll circumference 50 as shown in
In a roll placement step 106, and as shown in
After the measurement is completed, the measurement data is processed in a processing stage 116 and used to generate a data file in the file generation stage 118. Then, several quality metrics are generated in the quality metrics generating stage 120. More specifically, depending upon the measurements obtained from step 114, a maximum roll width quality determination is also displayed in the quality metric generating stage 120. For example, the measurement data is first processed in a profile generating program and displayed to the operator on a screen 60 (in the quality metric generating stage 120) as a quality metric in the form of a sidewall profile 62, as shown in
The screen 60 is initially interactive and allows the operator to magnify (zoom) portions of the profile by engaging a zoom button 68. If there are any concerns with the data, the operator can engage the EXIT button 70 and repeat the measurement. Finally, a data file is created and saved in a data file creation step 118. This file will contain the measurement height data in millimeters for each point of resolution. In the preferred embodiment, and in accordance with use of the Model AR600-1 Laser Displacement Sensor from Acuity Research as the distance measuring sensor 17, each data point represents a radial distance of 0.0008 inch (0.02 mm) on the X-axis (horizontal axis) of the sensor. The laser spot diameter is 0.005 inch, so approximately 11 to 12 data points will span each 0.009 inch thick lap of paper. Plotting roll height (width) vs. data point produces the sidewall profile 62 of one half of the roll 12.
As mentioned above, one quality metric relates to the maximum roll width, which in the sidewall gauge is determined by the bottom to top width w (see
Another quality metric relates to sidewall appearance rather than to any particular roll dimensional attribute, such as roll width. As it turns out, some customers tend to correlate roll quality with the visual appearance and feel of the sidewall. In other words, a “rough” or “uneven” sidewall as seen and felt by the customer connotes poor quality, while a “smooth” sidewall connotes high quality. What has been lacking in the quality inspection process has been some way to rate and quantify the aesthetic appearance of the roll sidewall. Thus, there is a need to create a metric that would correlate to the visual appearance of the sidewall, since this is what customers see and feel. Considering this problem from the vantage of a customer's “sight”, when one views a roll laid on its side, the best way to “see” the roughness in the sidewall is to shine a light at a low incident angle in the radial direction and view the sidewall from above, as shown by the visualization in
In order to develop the shadow quality metric, a test set of rolls were used to empirically develop the requirements for incident angle 82 and minimum shadow length 94 as perceived by the human eye that results in the best correlation of this metric to the visual appearance of a roll. A 3-degree angle 82 and a minimum shadow length of 1.5 mm (0.060 inch) were found to work well. (Obviously, other angles and minimum shadow lengths may work sufficiently well, depending on customer requirements and tastes, and are intended to be within the purview of the claimed invention.) Therefore, unless a shadow is at least 1.5 mm long, the laps within the shadow are counted as “illuminated”. (Note that there is no actual illumination by a real light source associated with practice of the method according to this invention. Reference to using a low incident light source to view sidewall roughness is only intended to explain the approach. In actuality, the determination of the shadow metric is achieved solely by mathematical manipulation of the profile data as disclosed in connection with
The shadow quality metric is then defined as the ratio of “illuminated” data points to the total number of data points. Thus a rating of 1.0 or 100% would mean that the roll was smooth enough that there were no shadows longer than 1.5 mm, and a lesser rating—less than 1.0 or less than 100%—would mean that a corresponding smaller proportion of the roll was “illuminated”. For example, a rating of 23% would mean that 23% of the sidewall was “illuminated” and 77% of the sidewall appeared to be in shadow. Several caveats are in order. This metric does not include the core or start zones, that is, the initial few laps, but only the wind zone between the start zone and the outer diameter of the roll. Since a different result might occur depending on whether the light were shone from the outside of the roll in or from the inside out, the program does the computation for both directions and returns the worst case. Note that subtle dishing of the laps in the sidewall is generally not discernible by the human eye, and so does not have an impact on this metric. Generally, large shadow values as defined actually correspond to “smoother” sidewalls.
The goal of the shadow metric computation is to mimic the subjective reaction of a person viewing a roll sidewall. If a person would rate a roll's sidewall quality from 0 (terrible) to 1 (perfect), this routine should generate a similar number based on the information returned from the sidewall quality gauge.
While the shadow metric can be calculated in a number of ways once the light/shadow analogy is understood as explained in connection with
-
- 1. rot2d (two-dimensional rotation of a set of (x,y) data) in
FIG. 12 . - 2. shadow (determines which data points would be in shadow if the roll is viewed under light at a specified angle, for both “left” and “right” views) in
FIGS. 13A and 13B . - 3. shadowcalc (a procedure using “shadow” to compute the shadow metric) in
FIGS. 14A and 14B .
Function rot2d (FIG. 13 ) is characterized by [xo,yo]=rot2d(x,y,alpha,xc,yc) with inputs and outputs as follows: - x, column vector of x-coordinates of a set of points
- y, corresponding vector of y-coordinates of a set of points
- alpha, the angle in radians to rotate the set of point (x,y) about the rotation center (xc,yc)
- xc, x-coordinate of center of rotation (defaults to 0)
- yc, y-coordinate of center of rotation (defaults to 0)
- xo, column vector of rotated x-coordinates
- yo, corresponding column vector of rotated y-coordinates
Function shadow (FIGS. 13A and 13B ) is characterized by the function [seenleft,seenright]=shadow(x,d,ang), where function “shadow” computes 0-1 vector results for a “left” view (looking from the core outward) and a “right” view (looking from the outside of the roll toward the core). Inputs and outputs to function shadow include: - x is the x-coordinate (radius) in mm
- d is the y-coordinate (height in gauge) in mm
- ang is the angle of the “light” used to “view” the roll
- seenleft is a vector the same length as x and d, containing 0 if the data point is in shadow as viewed from the core of the roll looking out; otherwise 1
- seenright is a vector the same length as x and d, containing 0 if the data point is in shadow as viewed from the outside of the roll looking in; otherwise 1.
The shadowcalc procedure (FIGS. 14A and 14B ) uses the results from function shadow to compute the “shadow metric”. The procedure operates by finding all the results files from data processed by another program called “sidewall”, and adding the shadow metric to those results (or replacing them if the shadow metric is already present).
- 1. rot2d (two-dimensional rotation of a set of (x,y) data) in
The invention has been described with reference to a preferred embodiment; However, it will be appreciated that variations and modifications can be effected by a person of ordinary skill in the art without departing from the scope of the invention. For example, other quality metrics may be derived from the data, including without limitation web-to-core offset, web offset at start, maximum peak-to-valley sidewall amplitude, and the average sidewall slope (a measure of dishing). The advantage of the sidewall gauge as described, which provides the data associated with the roll sidewall profile, is that it gives a process engineer an insight into the process, thereby enabling the engineer to determine, for example, whether the problem is at the winder (e.g., a wobble problem) or further into the web travel (e.g., a weaving problem).
Parts List
- 10 vertical axis
- 11 core
- 12 wound roll
- 13 sidewall
- 14 magnified sidewall area
- 15 profile
- 16 lap
- 17 distance measurement sensor
- 17a direction
- 18 laser beam
- 19 computer
- 20 display
- 22 housing
- 24 left framing members
- 25a left panel
- 25b right panel
- 25c rear panel
- 26 right framing members
- 28 door
- 30 platform
- 32 roll position stop
- 34 roll position stop
- 35 distance
- 36 ultrasonic sensor
- 40 track (horizontal)
- 41 powered slide (horizontal)
- 41′ direction (horizontal)
- 42 powered slide (vertical)
- 42′ direction (vertical)
- 43 track (vertical)
- 44 monitor (touch screen, dark capable)
- 50 roll circumference
- 52 line of measurement
- 60 screen
- 62 sidewall profile (raw data)
- 64 maximum width
- 66 max width quality metric
- 68 zoom button
- 70 exit button
- 80 light rays (for illustration of concept only)
- 82 low incident angle
- 84 light source (for illustration of concept only)
- 86 observer's viewpoint
- 88 magnified portion
- 90 illuminated laps
- 92 shadow laps
- 94 minimum shadow length
- 100 calibration step
- 102 monitor selection step
- 104 roll preparation step
- 106 roll placement step
- 108 door closing step
- 110 roll width entering step
- 112 roll position checking step
- 114 measurement step
- 116 processing stage
- 118 data file generation stage
- 120 max width quality metric generation stage
- 122 width data block
- 124 specification look up block
- 126 max width block
- 128 metric determination block
Claims
1. An apparatus for measuring a sidewall characteristic of a wound roll, said wound roll comprising a strip of material wound about an axis, thereby forming a wound roll having concentric windings parallel to the axis with an upstanding sidewall with edges extending radially from the axis, said apparatus comprising:
- a housing;
- a platform mounted in the housing having a surface adapted to receive the wound roll;
- a distance measuring sensor supported in the housing for movement along a predetermined line of measurement extending across at least a portion of a sidewall of the wound roll for measuring the sidewall characteristic; and
- a processor for processing the sidewall characteristic and generating at least one quality metric representative of the quality of the roll.
2. The apparatus as claimed in claim 1 wherein the sidewall characteristic measured by the distance measuring sensor comprises distance data taken along the line of measurement, said distance data corresponding to the distance of the upstanding edges of the lap windings from the platform surface.
3. The apparatus as claimed in claim 2 wherein the wound roll comprises a strip of material wound about a core and has a width determined from the surface of the platform to one or more of the upstanding sidewall edges or protruding core and the quality metric comprises a profile of the width dimension as seen from the sidewall of the wound roll.
4. The apparatus as claimed in claim 3 wherein the processor generates a maximum roll width quality metric based on the profile of the width dimension of the sidewall.
5. The apparatus as claimed in claim 4 wherein the maximum roll width quality metric is determined by comparing the profile to a maximum width and failing the roll if any part of the profile or core exceeds the maximum width by a predetermined amount.
6. The apparatus as claimed in claim 1 wherein the processor generates a quality metric that correlates roll quality with the visual appearance of the sidewall.
7. The apparatus as claimed in claim 6 wherein the distance measuring sensor returns data points along the line of measurement and the visual appearance of the sidewall is determined by the calculation of the relative presence of shadow areas comprising data points that would be shadowed if the sidewall were to be illuminated by light of low incident angle.
8. The apparatus as claimed in claim 7 wherein the processor includes means for accumulating shadowed data points and determining length of said shadow areas.
9. The apparatus as claimed in claim 8 wherein the processor generates a shadow quality metric by determining the ratio of ((total number of data points−the number of data points comprising shadow areas greater than a predetermined length)/(total number of data points)).
10. The apparatus as claimed in claim 1 including a monitor attached to said housing.
11. The apparatus as claimed in claim 1 further including one or more positioning members arranged on the platform for confining the wound roll to a specified location on the surface of the platform.
12. The apparatus as claimed in claim 11 wherein the positioning members are arranged in a v-shape and a sensor is arranged at the vertex of the v-shape to check the positioning of the roll on the platform.
13. The apparatus as claimed in claim 1 including a door that substantially closes over the housing when the distance measuring sensor is taking a measurement.
14. The apparatus as claimed in claim 1 wherein the distance measuring sensor is a triangulation sensor using a laser light source, and the light source emits in the infra-red wavelength range so as not to expose light-sensitive roll materials.
15. A method for measuring sidewall quality of a wound roll, said wound roll comprising a strip of material wound about an axis, thereby having concentric windings parallel to the axis with an upstanding sidewall with edges extending radially from the axis, said method comprising the steps of:
- positioning the wound roll on a planar surface with the axis perpendicular to the planar surface and with one edge of the sidewall exposed in an upstanding position;
- positioning a distance measuring sensor above the sidewall for movement along a predetermined line of measurement extending across at least a portion of the sidewall of the wound roll;
- moving the distance measuring sensor along the line of measurement and generating a plurality of data points; and
- processing the data points to generate at least one quality metric representative of the quality of the roll.
16. The method as claimed in claim 15 wherein the data points measured by the distance measuring sensor comprise distance data taken along the line of measurement, said distance data corresponding to the distance of the upstanding edges of the lap windings from the platform surface.
17. The method as claimed in claim 16 wherein the wound roll comprises a strip of material wound about a core and has a width determined from the planar surface to one or more of the upstanding sidewall edges or protruding core and the quality metric is derived from a profile of the width dimension as seen from the sidewall of the wound roll.
18. The method as claimed in claim 17 wherein the quality metric comprises a maximum roll width quality metric based on the profile of the width dimension of the sidewall.
19. The method as claimed in claim 15 wherein the quality metric correlates roll quality with the visual appearance of the sidewall.
20. The method as claimed in claim 19 further comprising the step of determining shadowed data points by the presence of shadow areas comprising data points that are shadowed if the sidewall were to be illuminated by light of low incident angle.
21. The method as claimed in claim 20 further comprising the step of accumulating shadowed data points and determining a length of said shadow areas.
22. The method as claimed in claim 21 wherein the quality metric is a shadow quality metric that is obtained by determining the ratio of ((total number of data points−the number of data points comprising shadow areas greater than a predetermined length)/(total number of data points))
23. The method as claimed in claim 15 further including the steps of locating a calibration fixture with one or more defined calibration steps on the planar surface and calibrating the distance measuring sensor relative to the defined calibration steps.
24. A method for measuring sidewall quality of a wound roll using a sidewall position measuring sensor, said wound roll comprising a strip of material wound about an axis, thereby having concentric windings parallel to the axis with an upstanding sidewall with edges extending radially from the axis, said method comprising the steps of:
- calibrating the position measuring sensor relative to a calibrating fixture placed on a planar surface;
- inspecting and preparing the wound roll for a sidewall measurement;
- positioning the wound roll on a planar surface against one or more roll placement stops with the axis perpendicular to the planar surface and with one edge of the sidewall exposed in an upstanding position;
- enter data pertaining to the measurement, including a nominal width of the wound roll;
- moving the distance measuring sensor above the sidewall along a predetermined line of measurement extending across at least a portion of the sidewall of the wound roll, thereby generating a plurality of data points describing the height of the sidewall edges above the planar surface;
- generating a data file comprising the data points taken during the measurement; and
- processing the data file to generate at least one quality metric representative of the quality of the roll.
25. The method as claimed in claim 24 wherein the quality metric is derived from a sidewall profile of the wound roll.
26. The method as claimed in claim 24 wherein the quality metric is maximum roll width acceptability of the sidewall width of the wound roll relative to the nominal width.
27. The method as claimed in claim 24 wherein each data point is evaluated as to whether it represents a sidewall edge that is shadowed in the presence of low angle grazing light and as to whether such shadowed data points accumulate to form adjacently positioned shadow areas, and wherein the quality metric is a shadow quality metric that is obtained by determining the ratio of ((total number of data points−the number of data points comprising shadow areas greater than a predetermined length)/(total number of data points)).
Type: Application
Filed: Nov 10, 2005
Publication Date: May 10, 2007
Inventors: John Wysokowski (Fairport, NY), Mark Abbey (Webster, NY), Loren Krise (Rochester, NY), Gerald Fritsch (Spencerport, NY), Robert Walton (Fairport, NY), Sandra Krise (Rochester, NY)
Application Number: 11/272,541
International Classification: B65H 59/38 (20060101);