JPH01155213A - Method and means for measuring thickness of film- or sheet-like wed - Google Patents

Abstract

PURPOSE: To eliminate uncertainty due to the nonuniformity of a film and to measure the thickness of the film accurately by measuring the distance from the surface of the film to a measurement head with three measurement heads arranged on both surfaces of the film and calculating the thickness of the film from the result. CONSTITUTION: Distance between measurement heads 4 and 11 is measured by an optical detector. A light source 12 for emitting a narrow luminous flux is arranged at the measurement head 11, the light source 12 emits light with a wavelength for hitting against a surface 3 of the measurement head 4 through a film 5, and the image of light point is formed on the position-sensing surface of a light receiver 13. In this case, for example, infrared ray radiation can be considered. Then, a signal with a level that is proportional to the distance between the measurement heads 4 and 11 can be obtained from the light receiver 13. Further, a signal is obtained also by a light source 6 and a light receiver 7 at the lower part of the film 5 and a light source 1 and a light receiver 2 at an upper part and the thickness of the film 5 is calculated from the three measurement values. The thickness can be similarly measured also for sheet-shaped web and paper as well as the film 5.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides for measuring the distance of the measuring heads from the respective surfaces of the web with the aid of measuring heads located on both sides of the web. A method for measuring the thickness of a film-like or sheet-like web with the aid of a given detector and a detector for measuring the distance of each measuring head from the surface of the web on each side of the web. The present invention relates to a means for measuring the thickness of a film-like or sheet-like web, comprising measuring heads positioned on both sides of the web at an arbitrary distance.

BACKGROUND OF THE INVENTION The general principle of operation of a web thickness gage machine in a paper machine is that the web has one surface in the stationary part of the detector and the other surface in the movable part of the detector (coinciding with the web). The distance of the movable part from the stationary part is
Measure, for example inductively. ). Correct measurement of the wall thickness is achieved if the detector always contacts the web under measurement uniformly on both sides. Therefore, the movable parts are made light so that they can move quickly and do not damage the web. As a result of this low weight, the flapping of the web allows the movable part to oscillate, so that the web fails to contact the detector on both its surfaces and thereby causes measurement errors. Accurate results will be obtained. Other disadvantages are that in each case the moving parts have a certain mass, and the inertia of this mass cannot quickly follow rapid changes in web thickness or web flutter; This has the consequence of giving inaccurate measurements.

In wall thickness detectors used in the field, modifications of the above principles are employed, but the basic principle remains that the web passes between two bodies, the distance between them is measured, and It is assumed that this distance is proportional to the web thickness, and in particular, web flapping causes errors in the measurement results.

Other states of the art in measuring web thickness are disclosed in U.S. Pat. is accomplished without contact with the web.

These methods suffer from the fact that the detector, supported by an extended support structure on both sides of the web, is subject to vibrations induced by the operation of the machine, which makes the results of the measurements inaccurate, especially the thickness to be measured. This reason cannot be used in the case of wide webs, since even the slightest vibrations lead to rather high errors, since the width is in the order of a few μm or at most a few mm.

(Problems to be Solved by the Invention) An object of the present invention is to eliminate the above-mentioned drawbacks. A particular object of the present invention is to provide a web thickness in which external inaccuracies in the measurements resulting from the motion of the web and from the machines that put it in motion, as well as attributable to non-uniformities of the web, can be eliminated. The object of the present invention is to provide measurement methods and means. Furthermore, the present invention provides a method and method in which the correct placement and measurements of the detectors used are not as critical as in existing methods, since the detectors themselves measure and take into account any minute errors that they are subject to in their placement and installation. The purpose is to provide a device.

SUMMARY OF THE INVENTION Reference is made in the claims to the unique features of the invention.

That is, the present invention provides a method for measuring film-like images with the help of measuring heads arranged on both sides of the web and with the aid of detectors provided in these measuring heads which measure the distance of the measuring heads from the respective surface of the web. A method for measuring the thickness of a sheet-like web, in which the distances between the measuring heads are measured in relation to each other, and the thickness of the web is calculated from the three results thus obtained. A method for measuring the thickness of a film-like or sheet-like web characterized by:

The invention also provides a film consisting of measuring heads positioned on both sides of the web at arbitrary distances, with detectors for measuring the distance of each measuring head from the surface of the web on each side of the web. Means for measuring the thickness of a film-like or sheet-like web, characterized in that the means has a detector for measuring the distance of measuring heads from each other. It is a means to measure.

(Function) In the measuring method of the present invention, measuring heads are arranged on both sides of the web to be measured, and the distance between them is measured at the same time as the distance of each measuring head from the web between them is measured. This is characterized in that the web thickness can be determined from these three measured quantities by analog or digital calculations.

The measuring means of the present invention has measuring heads installed on both sides of the web, and furthermore, these measuring heads have at least one detector for measuring the distance between the measuring heads. It is characterized by: moreover,
Each metering head has a detector for measuring the distance of the web surface on each side from the metering head.

By using the measuring method and means of the invention, the web thickness can be determined as required in each instance.
It can be measured substantially continuously or periodically. What is essential is that at all times a simultaneous measurement of the distance and spacing of the measuring heads from the respective web surface is made.

The advantage of the measuring method and means of the invention compared to the prior art is that vibrations or shocks caused by the environment, by machine operation or also by the uniformity of the web have no influence on the result of the measurement. Instead, by using three different detectors simultaneously as taught by the present invention, these interfering effects encountered in measurements made by conventional means are successfully eliminated. .

(Example) The present invention will be described in more detail below with reference to the accompanying drawings.

FIG. 1 shows one embodiment of the invention, FIG. 2 shows the embodiment of FIG. 1 seen from another direction, and FIG. 3 shows another embodiment of the invention. This shows that.

A measuring device according to the invention, illustrated in FIGS. 1 and 2, consists of two fairly adjacent measuring rods 4 and 1
1. The web to be measured is inserted between these measuring heads without contacting the measuring heads. The measurement head 4 includes a light source 1 that emits a narrow beam of light.

The light flux from this light source is directed downwardly to the upper surface 1 of the web 5.
4 and this illuminated point is reproduced as an image on the position-sensitive surface of the receiver 2. The position of the image of the illuminated spot on the position-sensitive surface of the receiver changes as the distance of the upper surface of the web from the metering head 4 changes:
Change. In other words, a signal U1 is obtained from the receiver 2, the magnitude of which is proportional to the distance of the measuring head 4 from the upper surface 14 of the web.

Similarly, below the web 5 there is a measuring radar 11 having a light source 6 emitting a luminous flux and a receiver 7, which has a size proportional to the distance of the measuring radar 11 from the lower surface 15 of the web 5. It emits a signal U2.

The measuring head 11 includes an inductive detector or transducer 8 which senses the lower surface 3 of the measuring head 4 and which is connected to the measuring head adjacent to the inductive transducer 8. A signal U3 proportional to the distance between 4 and 11 is provided. From this signal U3 the true distance L3 between the measuring heads 4 and 11 is obtained, and likewise the signal U1 gives rise to the true distance ta Ll of the measuring head 4 from the upper surface 14 of the paper, and also the signal U2 yields the true distance L2 of the radius 11 from the lower surface 15 of the paper. Therefore, the thickness of the paper T=L3
-Ll-L2 is obtained.

However, it is difficult to use one inductive transducer to measure the distance between the measurement heads at exactly the same point where the light beam of the optical detector meets the web. is located out of the virtual plane continuous with the optical detector. As can be seen in FIG. 2, if the measuring heads 4 and 11 are not constant in a given fixed position relative to each other, the distance between these measuring heads can be measured with the two detectors 8 and 9. , which makes it possible to measure the potential change in the relative position of the measuring heads and at the same time find the true distance from the respective measuring head at the measuring point of the optical detector.

FIG. 3 illustrates another embodiment of the invention, in which the distance between measurement heads 4 and 11 is measured by one optical detector. A light source 12 emitting a narrow beam of light is arranged on the measuring head 11, and this light source emits light with a wavelength such that it passes through the paper and impinges on the surface 3 of the measuring head 4, and the point of this light is The image is formed on the position sensitive surface of the photoreceiver 13. In this case, for example, infrared radiation can be considered. Next, a signal whose magnitude is proportional to the distance between the measurement heads is obtained from the light receiver 13.

By suitably selecting the entrance and exit of the light beam of the optical detector, all distances can be measured in a straight line perpendicular to the web, and thus:
Only one optical detector is required for measuring between the measuring heads 4 and 11, even in the case where the positions of the measuring heads relative to each other should be able to vary somewhat. .

Those skilled in the art will appreciate that other embodiments of the invention, which are in no way limited to the embodiments described above, and which are within the scope of the inventive concept as defined by the claims, may be realized. Obviously, modifications are possible. For example, other methods and other types of devices can also be used other than those shown above to measure the distance between the measurement heads and the distance between the measurement heads and the web.

(Effects of the Invention) As described above, according to the present invention, external inaccuracies in measurements resulting from the motion of the web and from the machines that put the web in motion, as well as due to non-uniformity of the web, are eliminated. The true web thickness can be measured at any time (continuously or periodically). Furthermore, in the present invention, the correct placement and measurement of the detectors used is not as critical as in existing methods, since the detectors themselves measure and take into account any minute errors to which they are subjected. , it becomes possible to perform measurements more easily.

[Brief explanation of the drawing]

FIG. 1 shows one embodiment of the invention, FIG. 2 shows the embodiment of FIG. 1 seen from another direction, and FIG. 3 shows another embodiment of the invention. This shows that. - 1, 6, 12... light source, 2.7.13... light receiver,
4.11...Measuring head, 5...Web, 8.9.
...Induction detector or transducer - 0 Patent applicant: Sensodec, Osakatie representative Patent attorney: Miki Hatta, Yorenbuido, Fujin Zentaka Figure 1, Figure 2

Claims (12)

[Claims] (1) With the help of measuring heads arranged on both sides of the web and with the aid of detectors provided in these measuring heads which measure the distance of the measuring heads from the respective surface of the web A method for measuring the thickness of a web, characterized in that distances between measuring heads that are correlated with each other are measured, and the thickness of the web is calculated from the three results thus obtained. A method for measuring the thickness of sheet-like or sheet-like webs. (2) The method according to claim 1, wherein the distance between the measurement heads is optically measured using a wavelength that is transmitted through a web inserted between the measurement heads. (3) The method according to claim 1, wherein the distance between the measurement heads is measured using an inductive measurement device. (4) The distance of the surface of the web from each measuring head is measured on the same line perpendicular to the web on which the distance between the measuring heads is measured. The method according to any of paragraph 3. (5) The distance between the measuring heads is measured using two detectors, and at the center point between the detectors,
4. A method according to any one of claims 1 to 3, characterized in that the distance of the surface of the web from each measuring head is measured. (6) A film-like structure consisting of measuring heads positioned on both sides of the web at arbitrary distances, each of which is equipped with a detector for measuring the distance of each measuring head from the surface of the web on each side of the web. Means for measuring the thickness of a sheet-like web, characterized in that the means has a detector for measuring the distance of measuring heads from each other. means of. (7) The means according to claim 6, characterized in that the means has at least two detectors for measuring the distance between the measurement heads. (8) A claim characterized in that the means comprises, in one of the two measuring heads, at least two detectors for measuring the distance between the measuring head and the web surface on the side of the measuring head. The means set forth in item 1 of the scope. (9) A patent characterized in that the means has an optical measuring means for measuring the distance between the measuring heads, and the measuring means uses a wavelength that is transmitted through a web inserted between the measuring heads. Means according to claim 1. (10) The means according to claim 6, characterized in that the means comprises an inductive measuring means for measuring the distance between the measuring heads. (11) The measurement head and the detector that measures the distance between the measurement heads are arranged so that the measurement point for each measurement is located on a straight line perpendicular to the web being measured. The means according to claim 6, characterized in that: (12) The means includes two detectors provided on the same measuring head such that the measurement of the distance of the measuring head from the surface of the web is performed at a substantially central point between the pair of detectors. The means according to claim 6, characterized in that the means has: