GB2167179A - Web caliper measurement - Google Patents
Web caliper measurement Download PDFInfo
- Publication number
- GB2167179A GB2167179A GB08525050A GB8525050A GB2167179A GB 2167179 A GB2167179 A GB 2167179A GB 08525050 A GB08525050 A GB 08525050A GB 8525050 A GB8525050 A GB 8525050A GB 2167179 A GB2167179 A GB 2167179A
- Authority
- GB
- United Kingdom
- Prior art keywords
- web
- measuring
- gap
- separation
- measuring apparatus
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
- G01B11/0691—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of objects while moving
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
- G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
- G01B21/08—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness for measuring thickness
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices With Unspecified Measuring Means (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
The thickness of a material, such as a web 10 of paperboard, particularly formed and undried paperboard, is measured as the web passes over a roll 14 by positioning measuring apparatus 12 adjacent the web 10 spaced from the roll 14 and independently and simultaneously measuring the separation A between a measuring sensor 24 and the roll 14 and the separation B between the measuring sensor 24 and the web surface and subtracting such latter measurement from said former whereby the difference therebetween indicates the web thickness. In a preferred embodiment, the sensor to roll measurement A is sensed by means of an inductive sensor 24 while the gap between the sensor 24 and the web surface is determined by means of a scanning optical sensor 26. <IMAGE>
Description
SPECIFICATION
Web caliper measurement
This invention relates to measurement of the caliper or thickness of a material, particularly of a thin web material such as formed and still wet paperboard on a cylinder paperboard machine with the measuring apparatus being spatially separated from the web surface so as to operate in a noncontact mode therewith.
In a number of industries, notable among which is the paper industry, continuous webs of sheet material are formed and are processed at high speed. In paperboard manufacture, for example, it is useful to be able to measure the web thickness or caliper after the paperboard is formed on the forming felt and before transfer to the drying section. At this location, however, the formed but still wet web is very delicate and easily disturbed.
Moreover, vibration and flexure of the web and supporting rolls make accurate measurement by noncontact methods extremely difficult since the vibration and deflection components can become substantial relative the web thickness.
It is a primary object of the present invention to provide novel and improved methods of noncontact measurement, particularly for the noncontact measurement of web material such as paperboard webs, especially formed yet still wet paperboard webs webs on a cylinder paper making machine prior to drying, and particularly so as to be essentially immune to the adverse effect of vibration or deflection.
It is another object of the present invention to provide such novel methods and apparatus for measuring the calliper of a web, as it passes over a roller which are especially accurate and substantially immune to adverse effects of vibration and/or roller deflection.
It is yet another object of the present invention to provide measuring apparatus which may be transversed across the travelling web and which is substantially immune to vibration and deflection of the traversing mechanism and does not require especially stiff supporting guide rails.
Pursuant hereto the present invention provides a method of measuring the thickness or caliper of web material comprising the steps of:
supporting one surface of the web on a surface, positioning measuring apparatus adjacent the web at the other side thereof generally opposite the supporting surface to define a gap therebetween,
sensing by means of the measuring apparatus the separation between the measuring apparatus and the supporting surface, independently and simultaneously sensing by means of the measuring apparatus the separation between the measuring apparatus and the other surface of web, and
comparing both the sensed separations and deriving from the difference therebetween the thickness of the web.
In a preferred embodiment, the separation between the measuring apparatus and the supporting surface is sensed by means of an inductive sensor while the gap between the measuring apparatus and the web surface is determined by means of a scanning optical sensor.
The invention will be described further, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a perspective schematic illustration of a web caliper measurement system and apparatus in accordance with the present invention;
Figure 2 is an enlarged partial elevational view of the sensing portion of the apparatus of Fig. 1; and
Figure 3 is a flow chart of the operation of the present invention.
In accordance with the present invention, a web of material 10 is detected by a noncontact sensing apparatus 12 as the web passes over a supporting roller 14. While in no way is it intended for the present invention to be specifically limited thereby, the invention has found particularly utility when applied to the caliper measurement of a web of formed but still wet paperboard web on a cylinder paperboard machine.
In accordance with the present invention, the sensing apparatus 12 may be fixed to the frame of the paperboard machine or, in view of its accuracy and immunity to vibration and deflection, may be readily mounted for traversal across the paperboard machine, generally parallel the roll 14, on guide rails 16. Drive means, such as a screw 18 and a drive motor 20 therefor, may be provided for traversing the sensing apparatus 12 across the web 10.
The sensing apparatus 12 comprises a generally U-shaped housing 2 which straddles the bight of the web 10 as it passes over roll 14. Mounted on the housing 22 is a first sensor designated generally by the reference numeral 24 for sensing and measuring the distance to the roll 14 through the web 10. Also mounted on the housing 22 is a second sensor designated generally by the reference numeral 26 for measuring the separation between the sensor 24 and the adjacent surface of the web 10. The distance between the sensor 24 and the roll 14 is indicated in Fig.
2 by the arrow A while the distance between the sensor 24 and the adjacent surface of the web 10 is indicated by the arrow B.
Many different sensors can be utilized for measuring the distances A and B, it only being necessary that the web 10 be transparent to the sensor 24 and visible to the sensor 26 and, also, that the sensor 24 also be visible to the sensor 26. In practice, it has been found that the use of an inductive sensor for the sensor 24 is highly practical and a scanning laser beam sensor may be utilized for the sensor 26. Specifically an Electro-Mike EMDT inductive sensor available from Electro Corporation of Sarasota, Florida, Model No.
PA11503, which is capable of measuring gaps between 0.050 inches (1.27 mm) and 0.500 inches (12.70 mm) has been found suitable for the inductive sensor 24. The sensor 24, and its associated electronics which provides
AC exitation-to a reactor (not shown) within the sensor 24, reacts to changes in inductance due to changes in the gap between the sensor 24 and the roller 14. Several different measurements can be utilized to determine these inductance changes, such as inductor current, inductor resistance, voltage drop across the inductance or a series resistor, and the like. For example, Kahoun, U.S. Patent 3,411,075 contains a substantial discussion of inductive sensing through a paper web. Preferably the roll 14 is ferro-magnetic, although other sensors may enable the roll 14 or other supporting surface to be of other materials.
A scanning laser beam sensor 26 that has been found useful is series 50 LaserMike available from Techmet Corporation of Dayton,
Ohio and having a measurement range of 0.010 to 1.950 inches (0.254 to 49.53 mm).
This instrument which is of well known construction will not be described herein in detail.
Suffice it to note that it contains a laser generator 28 which directs a fine beam of light via a fixed mirror 30 to a rotating or oscillating mirror 32 which provides rotary scanning or sweeping of the laser beam 34 across a lens 36 constructed to convert the rotary scanning beam into a parallel scanning beam.
The laser sensor 26 is positioned so that the parallel scanning beam is partially occluded by both the inductive sensor 24 and the web 10 so that the reduced width parallel scanning beam passing through the gap therebetween can be measured and processed to provide the measurement B. For example, a second lens 38 may be used to converge the parallel scanning beam radially onto a photosensor 40. For further details of the construction of the LaserMike for optical and measuring apparatus reference is made to U.S. Patents 3,765,774; 3,905,705; and 4,007992, assigned to Techmet Company of Dayton, Ohio, the supplier of the laser scanner utilized on the exemplary embodiment herein.
With reference now to Fig. 3, the output signal from the inductive sensor 24 and the optical sensor 26 are compared at a comparator 28 and the resultant signal representing the web thickness A-B then displayed or utilized for process control. Preferably, the outputs of the optical sensor 26 and the inductive sensor 24 are processed in a form so as to be linear and of the same scale or relative magnitude so a simple comparison operation can result in the quantity A-B. However, it will be readily apparent that both analog and digital techniques can be utilized to process the signals, regardless of their relative scales and linearity.
In any event, inasmuch as the sensors 24 and 26 are carried by the same relatively small frame, deflection of either the guide rails 16 or the roll 14, or vibration therebetween, will not affect the difference A-B but will affect both of them with equal magnitude in equal direction.
Claims (25)
1. A method of measuring the thickness or caliper of web material comprising the steps of:
Supporting one surface of the web on a surface,
positioning measuring apparatus adjacent the web at the other side thereof generally opposite the supporting surface to define a gap therebetween,
sensing by means of the measuring apparatus the separation between the measuring apparatus and the supporting surface,
Independently and simultaneously sensing by means of the measuring apparatus the separation between the measuring apparatus and the other surface of web, and
comparing both the sensed separations and deriving from the difference therebetween the thickness of the web.
2. A method as claimed in claim 1 for use when the web is optically non-transparent wherein the step of sensing the separation between the measuring apparatus and the web surface comprises partially passing a light beam through the gap between the measuring apparatus and the web by enabling the light beam to be partially occluded by the measuring apparatus and the web, and sensing the magnitude of the partially occluded light beam passes thereby by means of an optical sensor.
3. A method as claimed in claim 2 wherein the step of partially passing light beam through the gap between the measuring apparatus and the web comprises positioning a laser source to provide a parallel scanned beam to shine on one side of the gap and positioning a photo-detector on the other side thereof, and sensing the scan duration and thereby the width of the laser beam by means of the photo-detector as an indication of the size of the gap.
4. A method as claimed in claim 2 or 3 wherein the support surface comprises a roller, further comprising positioning the measuring apparatus so as to pass the light beam generally tangentially of the roller.
5. A method as claimed in any preceding claim further comprising traversing the measuring apparatus laterally across the web.
6. A method as claimed in any preceding claim for use when the web is magnetically transparent and the support surface is ferromagnetic wherein the step of sensing the separation between the measuring apparatus and the support surface comprises electromagnetically sensing said separation by means of an inductive sensor.
7. A method as claimed in claim 6 wherein the gap is defined between the web and the inductive sensor.
8. A method as claimed in claim 6 or 7, when dependent on any of claims 2, 3 or 4 wherein the inductive sensor and the optical sensor each produce electrical signals proportional to the respective gap distances sensed and wherein the step of comparing comprises scaling these signals to the same ratio of magnitude versus gap length and subtracting the scaled signal of the optical sensor from the scaled signal of the inductive sensor, the difference defining a scaled signal representative of the web thickness or caliper.
9. A method defined in claim 8 wherein said step of comparing further comprises displaying the derived web thickness or caliper.
10. A method of measuring the caliper of a moving web, such as a formed paperboard web, comprising the steps of:
passing the web over a ferro-magnetic roll,
positioning a measuring apparatus including inductive sensing means and optical sensing means adjacent the roll so that the web passes therebetween,
inductively measuring the separation of the measuring apparatus from the roll,
optically measuring the separation of the measuring apparatus from the facing surface of the web, and
subtracting from the separation of the measuring apparatus from the roll the separation of the measuring apparatus from the facing surface of such web whereby the difference therebetween corresponds to the thickness or caliper of the web.
11. A method as claimed in claim 10 wherein the step of inductively measuring the separation comprises generating a voltage signal proportional to the separation, the step of optical measuring the separation comprises generating a voltage signal proportional to the separation, and the step of subtracting comprises feeding both such voltages to a comparator.
12. Measuring apparatus for measuring the thickness or caliper of a web of material as it passes over a supporting surface comprising:
first gap measuring means, which is spaced from the supporting surface so as to define a gap through which the web may pass and which is operative to sense the separation between the first gap measuring means and the supporting surface;
second gap measuring means, which is spaced from the supporting surface and which is constructed and arranged for sensing the separation between the first gap measuring means and the adjacent surface of web material passing through the gap; and
comparator means for comparing the gap measurements of the first and second gap measuring means whereby the difference therebetween corresponds to the web thickness or caliper independent of any movement and of the relative separation of said measuring apparatus and said supporting surface.
13. Apparatus as claimed in claim 12 for use when the web is magnetically transparent and the supporting surface is ferro-magnetic, wherein the first gap measuring means comprises an inductive sensor.
14. Apparatus as claimed in claim 12 or 13 for use when the web is optically nontransparent, wherein the second gap measuring means comprises:
transmitting means for projecting a beam of light through the gap to be partially occluded by the web and the first gap measuring means, and
receiving means for receiving the partially occluded beam of light and generating an output signal functionally related to the degree of occlusion and, therefore, the separation between the first gap measuring means and the adjacent web surface.
15. Apparatus as claimed in claim 14 wherein the means for projecting a beam of light comprises a laser generator and means for parallel scanning the output thereof towards the gap.
16. Apparatus as claimed in claim 14 or 15 wherein the support surface comprises the surface of a roller, such beam of light being projected generally tangential thereto.
17. Apparatus as claimed in claim 14, 15 or 16 further comprising a generally U-shaped frame for the measuring apparatus, the transmitting means being mounted to project the beam from one end leg thereof and the receiving means being mounted on the other end leg thereof.
18. Apparatus as claimed in claim 17 for use when the web is magnetically transparent and the support surface is ferro-magnetic, wherein the first measuring means comprises an inductive sensor and wherein the inductive sensor is mounted on the bridging portion of the generally U-shaped frame and partially occludes the beam of light between the transmitting and receiving means.
19. Apparatus as claimed in any of claims
11 to 18 further comprising mounting means movably supporting the measuring apparatus for enabling the measuring apparatus to be traversed generally literally across the web.
20. Apparatus for measuring the thickness of caliper of a web material, such as formed paperboard, as it passes over a ferro-magnetic roll comprising, in combination:
inductive sensing means positioned adjacent the roll and spaced apart generally radially therefrom to define a gap therebetween through which the web is passed, the inductive sensing means being constructed and arranged to generate an output signal functionally related to the distance separating the inductive sensing means and the roll,
optical sensing means positioned for measuring through the gap constructed and arranged to generate an output signal functionally related to the distance separating the inductive sensing means and the facing surface of the web as it passes over the roll, and
means for comparing the output signals of the inductive sensing means and the optical sensing means and for providing an output signal functionally related to the difference therebetween and therefore functionally related to thickness of caliper of the web.
21. Apparatus as claimed in claim 20 further comprising a generally U-shaped frame, the outer legs of which generally straddle the roll across a tangent thereto, the optical sensing means comprising a light beam generator carried by one leg of the frame and a photoreceptor carried by the other leg of the frame whereby the light beam generated by the generator passes generally tangentially of the roll.
22. Apparatus as claimed in claim 21 wherein the inductive sensing means is mounted on the bridging portion of the frame between the legs, and the light beam generator is constructed and arranged to be partially occluded by both the inductive sensing means and the web as it passes over the roll so that the intensity thereof as seen by the photoreceptor varies proportionally to the spacing between the inductive sensor and the web.
23. Apparatus as claimed in claim 21 or 22 further comprising means for mounting the frame for traversing lateral movement across such web.
24. A method of measuring the thickness or caliper of a moving web substantially as hereinbefore described.
25. Apparatus for measuring the thickness or caliper of a moving web substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US66990484A | 1984-11-09 | 1984-11-09 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8525050D0 GB8525050D0 (en) | 1985-11-13 |
| GB2167179A true GB2167179A (en) | 1986-05-21 |
Family
ID=24688201
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08525050A Withdrawn GB2167179A (en) | 1984-11-09 | 1985-10-10 | Web caliper measurement |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2167179A (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3843300A1 (en) * | 1987-12-23 | 1989-07-13 | Karl Veit Holger Dr Ing | Measuring device for determining the thickness of films |
| WO1989007672A1 (en) * | 1988-02-18 | 1989-08-24 | Lauffenmühle Gmbh | Device for optically scanning the surface of an object under severe atmosphere conditions in order to identify fluctuating superelevations on this plane |
| EP0339985A2 (en) * | 1988-04-26 | 1989-11-02 | Mitsubishi Denki Kabushiki Kaisha | Method for measuring film thickness |
| EP0422545A2 (en) * | 1989-10-09 | 1991-04-17 | Sumitomo Heavy Industries, Ltd | Sheet thickness measuring apparatus |
| EP0486713A1 (en) * | 1990-11-19 | 1992-05-27 | FAG Kugelfischer Georg Schäfer Aktiengesellschaft | Thickness measuring device |
| US5327082A (en) * | 1992-01-13 | 1994-07-05 | Valmet Automation (Canada) Ltd. | On line electromagnetic web thickness measuring apparatus incorporating a servomechanism with optical distance measuring |
| US5666203A (en) * | 1995-08-31 | 1997-09-09 | Mannesmann Aktiengesellschaft | Measurement system for detecting a gap of a roll pair |
| WO2015110517A1 (en) * | 2014-01-27 | 2015-07-30 | Fosber S.P.A. | Device and method for measuring the thickness of a moving web material |
| WO2019177161A1 (en) * | 2018-03-16 | 2019-09-19 | 明産株式会社 | Sheet thickness measurement device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1297804A (en) * | 1968-12-03 | 1972-11-29 | ||
| US4311392A (en) * | 1979-09-21 | 1982-01-19 | Bridgestone Tire Company Limited | Thickness measuring apparatus for non-metallic sheet-shaped bodies |
-
1985
- 1985-10-10 GB GB08525050A patent/GB2167179A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1297804A (en) * | 1968-12-03 | 1972-11-29 | ||
| US4311392A (en) * | 1979-09-21 | 1982-01-19 | Bridgestone Tire Company Limited | Thickness measuring apparatus for non-metallic sheet-shaped bodies |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3843300A1 (en) * | 1987-12-23 | 1989-07-13 | Karl Veit Holger Dr Ing | Measuring device for determining the thickness of films |
| WO1989007672A1 (en) * | 1988-02-18 | 1989-08-24 | Lauffenmühle Gmbh | Device for optically scanning the surface of an object under severe atmosphere conditions in order to identify fluctuating superelevations on this plane |
| EP0339985A2 (en) * | 1988-04-26 | 1989-11-02 | Mitsubishi Denki Kabushiki Kaisha | Method for measuring film thickness |
| EP0339985A3 (en) * | 1988-04-26 | 1990-05-30 | Mitsubishi Denki Kabushiki Kaisha | Method for measuring film thickness |
| EP0422545A2 (en) * | 1989-10-09 | 1991-04-17 | Sumitomo Heavy Industries, Ltd | Sheet thickness measuring apparatus |
| EP0422545A3 (en) * | 1989-10-09 | 1991-07-03 | Sumitomo Heavy Industries, Ltd | Sheet thickness measuring apparatus |
| US5075622A (en) * | 1989-10-09 | 1991-12-24 | Sumitomo Heavy Industries, Ltd. | Sheet thickness measuring apparatus with magnetic and optical sensors |
| EP0486713A1 (en) * | 1990-11-19 | 1992-05-27 | FAG Kugelfischer Georg Schäfer Aktiengesellschaft | Thickness measuring device |
| US5210593A (en) * | 1990-11-19 | 1993-05-11 | Fag Kugelfischer Georg Schafer Kgaa | Gauge for measuring the thickness of an unsupported web |
| US5327082A (en) * | 1992-01-13 | 1994-07-05 | Valmet Automation (Canada) Ltd. | On line electromagnetic web thickness measuring apparatus incorporating a servomechanism with optical distance measuring |
| US5666203A (en) * | 1995-08-31 | 1997-09-09 | Mannesmann Aktiengesellschaft | Measurement system for detecting a gap of a roll pair |
| WO2015110517A1 (en) * | 2014-01-27 | 2015-07-30 | Fosber S.P.A. | Device and method for measuring the thickness of a moving web material |
| WO2019177161A1 (en) * | 2018-03-16 | 2019-09-19 | 明産株式会社 | Sheet thickness measurement device |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8525050D0 (en) | 1985-11-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |