RU2366932C2 - Method for control of paper web quality in process of its production and device for control of paper web quality in process of its production - Google Patents

Abstract

FIELD: physics, control.

SUBSTANCE: invention is related to methods for control of paper web quality. Invention consists in web illumination from top by line of observation and registration of reflected light with further processing of produced signals. Web is additionally illuminated at the bottom, besides mutual brightness of illuminations is set so that brightness of registered mirror-reflected component from web sections with maximum coefficient of reflection is comparable to registered brightness of radiation that has passed through web and is more than background reflected light.

EFFECT: improved reliability of control.

9 cl, 3 dwg

Description

The invention relates to methods for controlling the quality of a paper web during its production and to an optical monitoring system for determining the quality characteristics of a paper web.

The quality control of the paper web in the paper machine includes the prompt detection of various kinds of defects - violation of the continuity of the paper web, lightening and darkening, size and quality rejection of the yarn and other visual security features, and violations in their location. The methods and devices proposed to date for solving these problems did not possess a sufficient degree of information, flexibility and simplicity of design to solve complex problems when working with various types of paper web.

The disadvantages of the previously proposed devices and methods include:

obtaining incomplete optical characteristics of the controlled web when using the illuminator on only one side (RU 2294997, IPC D21F 7/06, G01N 21/89, published on 03/10/2007); the inability to sufficiently illuminate the canvas, which has its own texture and irregularities, especially when various security features are introduced into it (US 4879000, published July 11, 1989); instability to flutter (i.e. trembling or oscillation of the web in the direction perpendicular to its movement) of the web of the control system.

These and some other disadvantages are eliminated by the proposed system, including a control method and device.

The general structure of such systems, as a rule, includes one or another type of illuminator for illuminating the canvas, followed by registration of the reflected and / or transmitted light by a receiver, for example, a linear scanner with a CCD matrix (CCD camera), and subsequent processing of the received signals to obtain conclusions about compliance with the accepted quality standard.

The closest in overall structure is the optical monitoring installation for the production of cigarette paper RU 2224994 (IPC D21F 7/06, G01N 21/89, published 02.27.2004), which is selected as a prototype. The installation comprises an upper linear illuminator and a receiver located above the paper web, as well as a signal processing system.

The disadvantages of this device are the receipt of incomplete optical characteristics of the controlled web when using the illuminator on only one side, insufficient illumination of the web, which has its own texture and irregularities, especially when various security features are introduced into it, and the instability of the control device to flutter the paper web.

In the proposed device, two independent illuminators are simultaneously used with a common receiver for them, which improves the reliability and informativeness of the quality control of the paper web.

The specified technical result is achieved by the fact that in the method of controlling the quality of the paper web during its production, which consists in illuminating the web from the top along the line of observation and recording the reflected light with subsequent processing of the received signals, according to the invention, the web is also simultaneously illuminated from below, and the mutual brightness of the illumination is set so that the brightness of the recorded specularly reflected component from the sections of the canvas with a maximum reflection coefficient is comparable to the registered brightness of the radiation transmitted through the canvas and more than the background reflected light.

Additionally, on top of the canvas increase the luminous flux by expanding the angles of illumination of the observation line.

The specified technical result is also achieved by the fact that the device for controlling the quality of the paper web, comprising an upper linear illuminator and a receiver located above the paper web, and a signal processing system according to the invention further comprises a lower linear illuminator located under the paper web so that the illumination is from below and on top of the web occurs along the line of observation of the receiver.

The upper linear illuminator consists of a number of elementary light sources having a divergent radiation pattern in solid angle. The device can have at least one more upper linear illuminator, similar to the first one and located parallel to it, and the optical axes of both illuminators converge along the observation line.

The device may also contain more than one radiation receiver, all of which must be installed along the line.

In illuminators, LEDs are used as elementary light sources. The receiver and the lower illuminator are in different planes relative to the observation line.

The device may further comprise a system that collimates the radiation.

The device has an automatic marking unit for marking defective sections of the canvas.

In illuminators, it is preferable to use LEDs as elementary light sources. This allows you to get even in structure and sufficient brightness lighting. In addition, the range of modern LEDs allows you to make a choice of spectrum, brightness, radiation angle. High performance allows them to be used in an industrial environment.

The invention is illustrated by the following drawings.

Figure 1 - diagram of a device for controlling the quality of paper web.

Figure 2 - node backlight with upper and lower illuminators.

Figure 3 - upper illuminator.

The basis of the control device is the optoelectronic part, containing a block of linear scanning receivers, consisting of high-speed linear CCD cameras 1 (Fig. 1), an upper linear illuminator module 2, which generates the necessary radiation and its spatial distribution to illuminate the reflection of a section of the web along the observation line CCD-cameras and is an extended element with many point light sources based on LEDs, and a linear illuminator module for clearance 3, consisting of a number of LEDs with guide cylindrical lens. At the server rack 4, the information received from the CCD cameras is processed, frames of the web sections 5 are formed, technological deviations of the web are set according to the set parameters, the operation of industrial markers is controlled, and freeze frames of the web sections are transferred to the operator’s workstation. Operator’s workstation 6 is used to control the system, set controlled parameters and permissible technological deviations, view freeze frames and generate statistical reports.

Industrial markers 7 mark a section of the canvas when detecting technological deviations that exceed the permissible, and defects in the form of dark spots and holes.

The diving thread is indicated by position 8, the observation line is position 9.

The principle of illumination of the canvas by the upper and lower illuminators is shown in figure 2. Using a common receiver for both backlights, you can significantly reduce the cost of the system and get both reflective and luminous characteristics of the canvas, without increasing the total number of receivers.

Unlike the optical fibers used in the prototype, which have low efficiency, the inability to adjust for angles, and a number of other shortcomings, this system uses LEDs with high efficiency, durability, and a wide range at low cost as elementary light sources. This allows you to select the required radiation characteristics, the ability to set the illumination angles of the canvas. The upper illuminator is formed from LEDs in several rows parallel to each other, and the receiver observation line extending across the canvas. A series of superbright LEDs are used in the lower linear illuminator. Both illuminators create a highlighted strip on the canvas along the line of observation of the receiver. In the general case, white LEDs are used for backlights, but color can also be used to increase contrast or other control features. A linear scanning camera acts as a receiver.

Another important difference from the prototype and analogues is that if you want to get reflected light from inclined or curved sections of the canvas, for example, diving thread 8, then you need to illuminate the upper illuminator in wider angles, because the slope of the sections leads the reflected light at angles that prevent it from entering the receiver — the CCD camera. To solve this problem, the upper illuminator consists of several parallel rows of LEDs, forming a spatial illuminator illuminating the observation line 9 of the receiver 1 at the required angles.

It should be noted that the elements of the system have a modular design, which can be adjusted to the required control conditions and completed depending on the width of the controlled web. By changing the capture zone, the number of receivers used with the appropriate illumination across the canvas and resolution, you can adjust the system to the desired operating conditions. For these purposes, appropriate methods of fastening and arrangement of system nodes with adjustment options are provided.

Figure 3 shows the principle of operation of the upper illuminator for three, as an example, the tilt angles (circled) of a controlled diving thread 8.

This design of many LEDs also serves to minimize the effect of flutter on the quality of illumination of the canvas, because allows you to increase the area of uniform illumination not only in the plane of the canvas, but also with its vertical oscillation during movement.

In the proposed system, the module of the upper linear illuminator serves mainly to obtain the reflected component of surface illumination from areas with a high reflection coefficient, for example, diving protective threads located on the surface of the canvas. Since they have a higher reflectivity than the diffuse surface of the paper, for illumination on the surface of the paper web, the luminous intensity is several times lower than the luminous intensity of the emitter. Therefore, the upper emitter does not have a noticeable effect on the control of the paper web on the clearance.

The mutual brightness of the upper and lower illumination is set so that the brightness of the recorded specularly reflected component with a maximum reflection coefficient is comparable to the recorded brightness of the radiation transmitted through the canvas and more than the background reflected light. This makes it possible to dispense with a less bright upper illumination and not create glare from specularly reflected light in the receiving system.

The use of information obtained only from reflected light limits the controlling capabilities of the system, since we lose information about the internal heterogeneities and structure of the canvas, and also, in part, about its reverse side. The use of the second illuminator 3 under the canvas, in contrast to the prototype, eliminates this drawback, because allows you to get the characteristics of the lumen of the canvas.

Here it is required to apply a sufficiently bright light source, and we use super-bright LEDs that can illuminate the canvas with a fairly uniform radiation. To eliminate the effect of flutter, a collimating cylindrical lens is installed, near the focus of which the LEDs are located.

The video information coming from linear CCD cameras, the horizontal scanning of which is synchronized by the web motion sensor (not shown), is processed by the server rack 4, which, on the basis of the received data, forms a web frame and performs control of technological deviations and web defects. If deviations exceeding the specified tolerances are detected, the controller issues a command to mark the defective area of the web and signals a detected defect. Video information and technological deviations detected during the analysis are transmitted to the operator’s workplace 6, displayed on the monitor and recorded in the database for further statistical processing. Also, the operator’s workstation periodically from the server rack receives freeze-frames of the canvas on sheets, displays them on the operator’s monitor with a template overlay and measurement of current deviations.

The proposed method of controlling the quality of the paper web during its production and a device for controlling the quality of the paper web are intended for use in enterprises producing various types of paper products, in particular in the manufacture of paper protected from counterfeiting. When using this invention, reliable quality control of paper is provided, while the control device has high operational and technical indicators at its optimum cost.

Claims (9)

1. The method of controlling the quality of the paper web in the production process, which consists in illuminating the web from above along the line of observation and recording the reflected light, followed by processing the received signals, characterized in that they also conduct simultaneous illumination of the web from the bottom, and the mutual brightness of the lighting is set so that the brightness registered mirror-reflected component from sections of the canvas with a maximum reflection coefficient is comparable to the recorded brightness of the transmitted through the canvas cheniya and more of the background reflected light. 2. The method according to claim 1, characterized in that in addition, on top of the canvas increase the luminous flux by expanding the angles of illumination of the observation line, providing registration of the specularly reflected component from sections of the canvas having a slope or radius of curvature. 3. A device for controlling the quality of the paper web during its production, comprising at least one upper linear illuminator and at least one receiver located above the paper web, as well as a signal processing system, characterized in that the device further comprises a lower linear illuminator, located under the paper web so that the illumination from below and above the cloth occurs along the line of observation of the receiver with the ability to set the mutual brightness of the upper and lower illumination such that the brightness The detected mirror-reflected component from sections of the web with a maximum reflection coefficient is comparable to the recorded brightness of the radiation transmitted through the web and more than the background reflected light. 4. The device according to claim 3, characterized in that the upper linear illuminator consists of a number of elementary light sources having a divergent radiation pattern in solid angle. 5. The device according to any one of claims 3 and 4, characterized in that it has at least one more upper linear illuminator, similar to the first and located parallel to it, and the optical axis of both illuminators converge along the observation line. 6. The device according to claim 3, characterized in that it contains more than one radiation receiver, all of which are installed along the observation line. 7. The device according to claim 4, characterized in that the elementary light sources in the illuminators are made in the form of LEDs. 8. The device according to claim 3, characterized in that it contains a system that collimates the radiation of the lower illuminator. 9. The device according to claim 3, characterized in that it contains a node for automatic marking of defective sections of the canvas.

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