JP2018159567A - Paper inspection method comprising foreign matter removal step - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper inspection method which comprises a foreign matter removal step which removes a foreign matter contained in paper during production efficiently in a papermaking line.SOLUTION: In the paper inspection method for detecting and removing the foreign matter adhered to or mixed with paper during papermaking on a papermaking machine, it includes an imaging step which images the paper running on the papermaking machine, a determination step which compares a certain portion having lighting different from the paper with prestored acceptance criterion for the image captured in the imaging step and detects it as the foreign matter if it is out of the criterion and a foreign matter removal step which removes the foreign matter in a prescribed method.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a method for inspecting a paper in a wet paper state until moisture is dehydrated during a paper making process when the paper is manufactured.

  FIG. 1 is a block diagram showing a schematic configuration of a general long paper machine. The paper raw material liquid ejected from the head box (1) is dehydrated after a paper layer is formed by the wire part (2). The paper layer formed by the wire part (2) is further squeezed by the press part (3) and then thermally dried by the dry part (4) to become a paper (7). Then, after adjusting the smoothness of the paper surface by the calendar part (5), the paper is wound by the winding unit (6).

  In the paper (7) manufactured through these steps, defects such as foreign matters often occur on the paper surface or paper layer. Causes include foreign matters derived from paper raw materials as well as foreign matters such as metal pieces and minerals. Such foreign matters not only adversely affect the appearance of the paper (7), but even fine foreign matters that do not affect the appearance often cause problems in subsequent coating and printing processes. Moreover, since there is a concern about the influence on machine reading in the distribution process such as banknotes, passports, and securities, it is necessary to remove them.

  In such a situation, for example, a paper surface foreign material removing device that can remove foreign material that has entered a part of the fiber of a paper web has been proposed (see, for example, Patent Document 1). This device is a paper surface foreign matter removing device installed so as to come into contact with the traveling paper web surface in a coating process on the paper web, and a plurality of blades having a length equal to or longer than the traveling paper web width, A paper surface foreign matter removing device having at least a frame for holding the blade.

  In addition, it is possible to accurately detect foreign matters and defective parts such as paper having unevenness in which thickness and density are partially changed, and paper having a clearance without being affected by the shading or unevenness of the clearance. Has been proposed (see, for example, Patent Document 2). This device is used for transmitted light illumination to detect debris, paper entanglement, bubbles, bundling fibers, resinous foreign matter, foreign matter defects present in the paper layer or on the back surface, etc. By detecting the change in density and simultaneously irradiating the paper surface with the appropriate amount of reflected light illumination, the image processing device can reduce unevenness and unevenness due to gaps that are noise components when detecting foreign objects and defective parts. Thus, the paper inspection apparatus detects foreign matter and defective portions with high accuracy.

Japanese Patent Laying-Open No. 2015-178059 JP-A-2005-274522

  However, in the technique described in Patent Document 1, in the coating process (before coating), a part of the blade enters the fiber of the paper web by pressing the tips of a plurality of blades against the running paper surface. Although the foreign matter partly exposed three-dimensionally on the paper surface can be effectively removed, the foreign matter cannot be removed when the whole foreign matter is buried in the paper layer.

  The technique described in Patent Document 2 irradiates reflected light on one side of a sheet to be inspected, irradiates transmitted light from the other side of the sheet, and simultaneously receives the reflected light and transmitted light with a light receiver. Therefore, it is possible to detect foreign matter with high accuracy without being affected by the unevenness of the paper and the density of the paper that has been applied to the paper. Since it has voids, the amount of transmitted light is lower than that of wet paper with moisture, and it does not fundamentally improve the density difference between the paper and foreign matter at the time of inspection.

  The present invention is intended to solve the above-described problems, and provides a paper inspection method including a foreign matter removing process for efficiently removing foreign matters contained in a paper being manufactured on a paper making line of a paper machine. To do.

  The present invention, on the paper machine, pre-stores an imaging unit for imaging paper in papermaking with transmitted light, and a determination criterion for determining foreign matter, and detects the foreign matter by comparing with the determination criterion, A foreign matter inspection apparatus including at least a foreign matter removal unit for removing and collecting foreign matter based on information from the control unit for controlling the instruction for specifying and removing the position of the foreign matter Is a paper inspection method for detecting and removing foreign matter adhering to or mixed in the paper in the paper machine on the paper machine, the imaging step of imaging the paper running on the paper machine by the imaging unit, The control unit compares the image captured in the imaging process with a judgment criterion stored in advance for a portion having a difference in contrast with the paper, and detects it as a foreign object when it is out of the standard. Yo A sheet inspection method having a foreign matter removing step with a foreign matter removing step of removing foreign matter in a predetermined manner.

  Further, the paper inspection method including the foreign matter removing process according to the present invention uses the transmitted light to image the paper based on the position information after the foreign matter removing process to confirm the removal of the foreign matter. The method further includes a foreign matter removal confirmation step of reconfirming the presence or absence of foreign matter by comparing the image with a criterion.

  The paper inspection method including the foreign matter removing process according to the present invention performs transmitted light inspection in a wet paper state on a paper machine, so that light irregular reflection in the paper layer or on the paper surface is reduced and light can be easily transmitted. Therefore, it is possible to effectively detect foreign matters contained in the front and back sides of the paper and the paper layer.

  Further, the paper inspection method including the foreign matter removal process of the present invention can reduce the foreign matter contained in the waste paper which is a waste paper by removing the detected foreign matter on the paper machine, and at the time of recycling the waste paper The load of the fine selection work can be reduced and the paper quality can be improved.

  Furthermore, the paper inspection method provided with the foreign matter removing process of the present invention suppresses the occurrence of irregularities and scratches on various roll surfaces caused by foreign matter by detecting and removing the foreign matter at an early timing on the paper machine. It is possible to reduce the work load of the operator related to the life extension and maintenance of the roll.

The block diagram which shows schematic structure of a general long paper machine. Schematic of a general long paper machine. The block diagram which shows the structure of the foreign material removal apparatus of this invention. The figure which shows arrangement | positioning of each means which comprises the foreign material removal apparatus of this invention. The figure which shows specification of the position of an image input image and a foreign material. The figure which shows the specific arrangement | positioning of a foreign material removal part. The figure which shows another example of the specific arrangement | positioning of a foreign material removal part. The flowchart which shows the foreign material removal method of this invention.

  DESCRIPTION OF EMBODIMENTS Embodiments for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described below, and includes various other embodiments within the scope of the technical idea described in the scope of claims.

  FIG. 2 is a schematic view of a general long paper machine for producing paper (7). The paper machine to be used for carrying out the present invention is the long paper machine shown in FIG. Even if it is a general circular net paper machine, there is no particular limitation as long as a foreign substance inspection apparatus (M) described later can be installed. In the following embodiments, a long web paper machine will be described as an example.

  For the manufacture of paper, paper stock mainly consisting of pulp fiber, water, chemicals, filler, etc. flows out from the head box (1) onto the wire of the wire part (2). The stock on the wire is gradually dewatered downstream to form a paper layer.

  Next, water is squeezed in the press part (3), moisture is evaporated in the dry part (4), and the wet paper is dried to a predetermined moisture ratio. The paper (7) dried to a predetermined moisture ratio is glossed by the calendar part (5) and wound on a reel by the winding part (6) to become a completed paper (7).

  The paper (7) in the present invention is a general term for paper in various states in a series of processes in which a paper layer is formed on a paper machine and then dehydrated, dried and polished, and is particularly characteristic of the present invention. The wet paper as a point refers to the state of the paper between the outlet of the wire part (2) and the dry part (4). Details of the state of the wet paper will be described later.

  As shown in the block diagram of FIG. 3, the foreign matter inspection apparatus (M) of the present invention has an image pickup unit (P) for picking up an image of the surface of a wet paper to inspect the presence or absence of foreign matter, and if there is a foreign matter. A foreign matter removing unit (J) that removes the detected foreign matter, and a control unit (C) that controls the operation of each part, such as timing of imaging, determination of being a foreign matter, and identification of the position of the foreign matter.

  As shown in FIG. 4, the imaging unit (P) of the present invention is a part in which the traveling paper (7) is in a wet paper state containing sufficient moisture on the long paper machine, and the imaging means (8). And the irradiation means (9) so that the paper (7) passes between them. By capturing images in the wet paper state, the diffuse reflection of light in the paper layer or on the surface of the paper is reduced, and the paper (7) can easily transmit light. Therefore, foreign matters contained in the front and back sides of the paper and in the paper layer are effectively detected. It becomes possible to do. However, in order to image the wet paper with transmitted light, the wet paper is not supported by a wire, a blanket, or the like, and has a strength that enables the wet paper to run between rolls. It is necessary to provide an imaging unit (P) on the downstream side of the press part (3) and the upstream side of the dry part (4) where the wet paper web moisture is about 60% in terms of permeability and strength.

  In addition, as described above, the inspection of the foreign matter is performed in the wet paper state in the paper manufacturing process, and the detected foreign matter is inspected until the paper (7) is taken up by the winding unit (6). In order to avoid fluctuations in foreign matter position information due to paper expansion and contraction and roll damage caused by foreign matter, the imaging unit (P) and foreign matter removing unit (J) are dry parts. It is preferable to install it before (4).

  As described above, the inspection and removal of foreign matter in the present invention is preferably performed from the press part (3) on the long paper machine to the part before the dry part (4). What means will be used in practice will be described with reference to the schematic diagram of FIG.

  First, the imaging unit (P) is a part that continuously captures images of wet paper traveling on the long paper machine, and as shown in FIG. 4, after the press part (3) of the long paper machine, In addition, an image pickup means (8) such as a line sensor camera disposed on one side of the traveling wet paper, and an LED light source for illuminating the wet paper from a position facing the image pickup means (8) with the wet paper sandwiched therebetween The irradiation means (9) is provided. The vertical positional relationship between the image pickup means (8) and the irradiation means (9) is not particularly restricted. However, in consideration of prevention of dirt accumulation on the camera lens, maintainability, etc., the image pickup means (8) is directed downward from the upper side of the wet paper web. It is preferable to install in.

  Next, the control unit (C) will be described. The control unit (C) stores the foreign matter based on the image captured by the image pickup means (8) and the storage means for previously inputting and storing the light / dark difference (density value), dimensions, and the like, which are the criteria for determining the quality of the foreign matter. The image processing means for extracting effectively, the foreign matter is judged to be good or bad compared with the judgment criterion stored in advance, the position of the foreign matter is specified and the position information is output to the foreign matter removing unit (J), and the imaging unit (P) and determination means for controlling the operation of the foreign matter removing section (J).

  The identification of the position of the foreign substance in the determination unit described above will be described with reference to FIG. 5 showing the specification of the image input image and the position in the imaging unit (8). For example, the imaging unit inputs an image with a certain time as one frame in synchronization with the running speed of the wet paper in the running direction (S1) of the wet paper. For the input paper image, the image processing unit sets the corner (A, KA) of the paper image as the origin (0, 0), and determines the position of the foreign object (B) by the distance from the origin (0, 0) coordinates ( X1, Y1).

  Next, as shown in FIG. 6, the foreign substance removing unit (J) has foreign substance removing means (10) for removing foreign substances based on at least the position information of the foreign substance specified by the control unit (C). The foreign matter removing means (10) is provided with, for example, a foreign matter removing device (11) that removes the foreign matter in a spot manner using water pressure by a laser, an air gun or a spray nozzle, and the foreign matter removing device (11) on the paper machine. At least a guide rail (12). The foreign matter removing device (11) is of a movable type that moves on the guide rail (12) in the paper width direction (X1).

  In the case of this movable foreign matter removing device (11), one foreign matter removing device (11) is installed on the guide rail (12), and based on the positional information of the foreign matter from the control unit (C), the paper It moves in the width direction (X1) of (7), tracks the paper travel distance from the time of detecting the foreign matter to the foreign matter removing device (11), and at the timing when the foreign matter reaches the foreign matter removing device (11), Fire a laser, air gun, etc.

  In the case of the fixed foreign matter removing device (11), as shown in FIG. 7, a plurality (four in FIG. 7) of foreign matter removing devices (11) are installed on the guide rail (12) and controlled. Based on the position information of the foreign matter from the section (C), the foreign matter removing device (11) closest to the position of the foreign matter in the width direction (X1) of the paper (7), for example, from the left side in FIG. Since the second foreign matter removing device (11) is closest to the foreign matter, an instruction is given to the foreign matter removing device (11) from the control unit (C), the orientation is changed and the irradiation angle is adjusted, the laser is directed toward the foreign matter, Fire an air gun.

  When an air gun or water pressure is used for the foreign matter removing device (11), it is preferable to provide a foreign matter collecting means (13) for immediately collecting the removed foreign matter so that it does not scatter to the periphery of the long paper machine. As the foreign matter collecting means (13), a suction device disposed at a position facing the foreign matter removing device (11) with the paper (7) interposed therebetween can be used. When a laser is used in the foreign matter removing device (11), the foreign matter disappears, so that no particular recovery is required. Therefore, the foreign matter collecting means (13) is not an indispensable means, and may be appropriately installed depending on what kind of device is used for the foreign matter removing apparatus (11).

  Next, description will be made with reference to the flowchart of FIG. After the long net paper machine is in operation, it is confirmed that the paper making condition is stable, and the operator presses the inspection start button to start the inspection. At the start of the inspection, as an imaging process, first, an LED light source as an irradiation means (9) installed above and below the wet paper travel line, and an imaging means installed above the paper surface with the paper (7) in between. (8) The transmission of the wet paper through the line paper is started by the line camera. The number of line cameras and LED light sources to be installed may be appropriately set to one or a plurality of units in accordance with the width of the wet paper so that the entire width direction with respect to the running direction (S1) of the wet paper can be photographed.

  In the long net paper machine, generally, after the paper material forms a paper layer with the wire part (2), it is gradually dehydrated and becomes a wet paper having a water content of about 80% near the outlet of the wire part (2). Thereafter, the felt is applied to the wet paper in the press part (3) and compressed from above and below, so that the water content becomes about 60%. At this point, the wet paper can travel to some extent stably due to the strength of the wet paper itself, and is in a state suitable for imaging.

  Next, as a determination step, first, in the image processing means, image processing such as binarization processing generally known is performed on the input image picked up by the image pickup means (8), and a portion having a contrast difference with respect to the paper is detected. Compared with the reference value of the light and dark difference registered in advance in the storage means, if it falls outside the allowable range, it is extracted as a foreign object. The light / dark difference for determining the foreign substance is a so-called density value in 256 gradations. A foreign material such as paper stock in paper stock, paper stock entanglement, or externally mixed metal powder or dust is captured darker than the paper when it receives transmitted light from the irradiation means (9). Further, in the case where a piece of transparent film or the like is mixed, when the transmitted light from the irradiation means (9) is received, the transmitted light amount is higher than that of other portions, and the image is brighter than the paper. The area value of the foreign matter extracted as a result of the difference in brightness from this paper is compared with a reference value registered in the storage means in advance. If the reference value is less than the reference value, it is “good”. Determination of “loss” is performed by the determination means.

  If it is determined in the determination step that a foreign object is present, the position of the foreign object is specified and the foreign object is removed as already described with reference to FIG.

  In this removal step, the foreign matter is received by the foreign matter removing means (10) based on the imaging signal from the line camera and the encoder pulse signal indicating the transport timing of the transport line of the paper (7) in response to the NG signal from the control unit (C). ), The laser beam, the air gun, and the like are irradiated toward the paper (7) to remove the foreign matters in a spot manner.

  When the paper manufacture on the paper machine is stopped, or when the inspection and the foreign matter removal are not required even during the production, the inspection and the foreign matter removal can be stopped. In either case, the operator presses the inspection end button to stop.

  As described above, when the movable foreign matter removing device (11) is used, the foreign matter paper is removed from the foreign matter removing device (11) as the device moving step after the judging step and before the foreign matter removing step. The position information in the width direction (X1) is transmitted from the control unit (C), and based on the transmitted position information of the foreign matter, along the guide rail attached to the long paper machine frame so as to straddle the paper travel, the foreign matter The removal device (11) is moved. In the case of the fixed type, this step is unnecessary.

  Also, when removing foreign matter from the paper (7) by air gun, water pressure, etc., foreign matter removed in the foreign matter removal process, paper waste generated at the time of foreign matter removal, paper dust etc. on the running paper or long paper machine In order to avoid scattering to the periphery, as a recovery step, for example, as shown in FIG. 6 or FIG. 7, the foreign matter recovery means (13) installed with the foreign matter removal means (10) and the paper (7) sandwiched therebetween. At the same time as removing the foreign matter, the suction and collection of the removed foreign matter is performed. The foreign matter collecting means (13) includes a dust collector (14) provided outside the long net paper machine for sucking and collecting foreign matter. This step is not necessary when the foreign matter itself disappears by removing the foreign matter with a laser or the like.

  The size of the foreign matter collecting means (13) is not particularly limited, and a fixed suction device larger than the width direction of the running paper (7) is preferable as shown in FIG. 6 or FIG. For example, a small suction device that moves to a position corresponding only to the irradiation position from the foreign substance removing device (11) may be used.

  In order to confirm whether or not the foreign matter was actually removed when the foreign matter was detected and removed, an imaging unit (P) is provided again downstream from the foreign matter removing means (10) described above, and again It is preferable to perform the imaging step and the determination step in order to inspect for the presence of foreign matter. The roles and specific means of the imaging unit (P) and the control unit (C) in the reexamination may be the same as those described above.

DESCRIPTION OF SYMBOLS 1 Headbox 2 Wire part 3 Press part 4 Dry part 5 Calender part 6 Winding part 7 Paper 8 Imaging means 9 Irradiation means 10 Foreign substance removal means 11 Foreign substance removal apparatus 12 Guide rail 13 Foreign substance collection means 14 Dust collector M Foreign substance inspection apparatus P Imaging Part C Control part J Foreign object removal part S1 Paper running direction

Claims (2)

On the paper machine, an imaging unit for imaging paper in papermaking with transmitted light and a criterion for determining foreign matter are stored in advance, and the foreign matter is detected by comparing with the criterion, and the foreign matter is detected. A foreign substance inspection apparatus including at least a foreign substance removing unit for removing and collecting the foreign substance based on information from the control unit, and a control unit that controls instructions for specifying and removing position information of A paper inspection method for detecting and removing on the paper machine the foreign matter adhering to or mixed in the paper in the papermaking by the foreign matter inspection device,
An imaging step of imaging the paper running on the paper machine by the imaging unit;
A determination step of comparing a portion having a difference in contrast with the paper with the determination criterion stored in advance with respect to the image captured in the imaging step by the control unit and detecting as a foreign object when the reference is not satisfied,
A paper inspection method comprising a foreign matter removing step of removing a foreign matter by a predetermined method by a foreign matter removing means.   In order to confirm the removal of the foreign matter, after the foreign matter removal step, based on the position information, the paper is imaged using transmitted light, and the captured image is compared with the determination criterion. The paper inspection method comprising the foreign matter removal step according to claim 1, further comprising a foreign matter removal confirmation step of reconfirming the presence or absence.

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