MXPA99001452A - Process for elimination of paper defects in continuous paper production - Google Patents

Abstract

A process for elimination of paper defects during continuous paper production which reduces time lost due to defect correction has the following steps:a) recognition and localization of the paper defect by means of sensors (5) directed at the running paper web (4);b) detection or calculation of the speed of the paper web (4) between the sensor (5) and a station (6) for defect correction positioned downstream from the sensor (5);c) on the basis of the speed of the paper web, calculation of the arrival time of the web segment with the paper defect at the station (6) for defect correction;d) before arrival of the web segment with the paper defect at the station (6) for defect correction, reduction of the web segment speed to a lower value than normal speed or to zero, e) automatic removal of the paper defect in station (6) for defect correction and f) restoring the web section to normal speed.

Description

PROCEDURE TO ELIMINATE DEFECTS IN THE PAPER IN CONTINUOUS PAPER PRODUCTION DESCRIPTION OF THE INVENTION: The present invention relates to a procedure for the elimination of defects in paper in the continuous production of paper. The papermaking machines that work continuously are distributed in stations, material supply, sifting part, pressing part, drying part, dry polishing workshop, winding. In the material supply, the suspension of the aqueous material is evenly distributed over the width of the band, in order to guarantee optimal leaf formation. In the next sifting part, the paper sheet itself is formed by means of a filtering process. The individual paper fibers are fixed in a wet fleece in their final place. Subsequently, in the pressing part, the excess water is expelled by means of pressure from the fiber paper web. The paper web thus passes through multiple presses arranged one behind the other. After subsequent drying, the paper is polished, for which a glazing or polishing tool consisting of two rollers is generally used, and which frosting causes a compression of the paper and with this or uniform influence on the thickness of the paper . Finally, roll the paper band over a drum. «EF. 29469 During the production procedure mentioned, faults may occur in the paper web. These can be holes or tears along the longitudinal edges of the paper web, as well as later dark or light spots on the paper web. In addition, undesirable material lumps or folds may appear in the production line of the running paper web. These failures do not disturb the consequent transport of the paper web within the papermaking machine. At the next processing station, on the other hand, roughly or partially torn pieces may be present in the roughly connected stretch machine or also in the pressing macruin. It is therefore necessary to eliminate such paper failures, before the paper strip arrives at a later elaboration stage. The elimination of paper failures has, up to now, been manually, when by means of detectors they find faults in the paper. paper band guarded in each position where they are, a mark is provided, and in a subsequent station when the paper strip section so characterized is approached, it is braked, so that at a slow creep speed a stick can stick in place d fails by an operator. Depending on the type of failure, the paper section with the flaw is also eliminated, so as to apply a portion of adhesion over the entire width of the paper band. This way of removing the flaws is costly in time since the speed of the paper roll and with this d the entire paper web must be decreased to a slow drag or even stop, by then manually? eliminate the places of failure. But even this elimination, which is long and costly, may not be enough to eliminate the paper failures in the following processing stations with causes of tearing safely. The present invention proposes the task of creating a process with which in the manufacture of paper s eliminate faults in the paper web contma decrease in lost time. To solve this task, a procedure is proposed to eliminate paper failures in the continuous paper manufacture, with the following steps: a) recognition and localization of the paper fault by means of a detector directed towards the paper web run; b) capturing or calculating the speed of the paper band between the detector and a station to remove the subsequently connected failing at a distance from the detector; c) by means of the speed of the paper web, calculate the moment of the entrance of the band section that has the paper failure in the station to remove the fault; d) still before the band section presents the fault between the station to remove the fault, s makes a decrease in the speed of the band section a value decreased with respect to the normal or null speed e) automatic elimination to remove the fault; and f) increase in the speed of the band section at normal speed. According to the invention, therefore, only the recognition and localization of the paper fault is carried out by means of usual means, properly suitable detectors, whose picking organs are directed towards the paper web. Unlike the means applied so far, it performs a capture or calculation of the speed of the paper band between the detector and a station arranged after the detector to remove the fault. By means of that speed each moment is calculated, that moment in which the band section that has the fault will enter the station to eliminate the failure, where before that arrival is made, the speed of the band section is decreased at a value decreased with respect to normal or zero speed. In the station was made at each moment, which can be calculated by means of the speed of the paper web by means of appropriate devices, l automatic elimination of paper failure. Then the speed of the band section is raised again to its normal speed. Unlike as in the manual removal of known failure, it is not necessary to reduce the speed of the paper band at the speed that is necessary for precautionary and manually eliminate the fault. Better because of the evaluation of the detection signals, an experience has been gained that allows recognizing with respect to the interior of the system that the speed of the paper band should be established at the next station to safely remove the failure in the paper. To this end the detector can be equipped, not only to recognize the paper fault and to locate it, but also to determine its character, for example the class and contour of the paper fault as well as its location in reference to the width of the band. . All this information can be obtained from inside the system to be evaluated, to determine the speed of the band section inside the station, where the fault must be removed, at its correct value. In this way, the loss of time caused by the elimination of faults is eliminated in the manufacture of paper, up to an absolutely minimal size. In one conformation of the procedure, it is proposed that the paper band before it reaches the detector, travel another detector, and that this other detector performs a preliminary or coarse capture of the paper failure, where the detector is equipped for an additional capture of character of the paper fault, for example its class and contour. In this way it is possible that the paper web and with this machine to manufacture the paper have a normal operation with a very high speed, since the next detector will be exclusively directed to recognize the faults and simultaneously to locate them. The measurement characteristic of this detector is therefore directed more to a rapid capture, and less to a detailed capture. The details are captured rather by the detector arranged in the station to remove the faults. Such details are the kind of paper its outline as well as the position of the paper failure and reference to the width of the paper web. Preferably, the moment of the entry of the band section presenting the paper fault previously detected in the detector is calculated by means of the velocity of the paper web on the way to the detector. In another embodiment of the method, it is proposed that the speed of the band section containing the failure in the paper still before the band section passes through the detector decreases to a reduced value with respect to the normal speed immediately before the section of the band at the fault removal station, at a value below normal or even null. With the invention it is further proposed that the elimination of paper failures be carried out by the surface covering of the failure places with a fluid that hardens rapidly. The application of the fluid can, according to a first variant, be carried out by spraying on the one hand or both sides of the failure point. According to a second variant, the fluid is applied at the fault location by means of an application roller. A lacquer that hardens rapidly is particularly suitable as a fluid. The procedure is suitable both for use in the framework of an on-line production and also in off-line paper production. In the first case, the station, the detector and the second detector are arranged along the length of the paper web, so that automatic failure of the paper at the speed of the paper web in the manufacturing machine takes place. paper, while in the second case, the second detector places next to a paper machine, and the station and detecting along a furling or pre-furling device disposed after the paper machine. The winder or pre-furler represents the joining member between the paper making machine and the stretching machine. In Figure 1, the drum on the end of the pap band developed from the paper machine is shown on the right. This band of pap can present faults in the paper in different places. detection of these faults is carried out in the pre-connected pap machine, where the location of the paper faults reference to the length of the paper strip wound in the drum is stored in a control unit. After the drum is has tensed with the pre-rolled, and "knows" the system where they are within the length of the band of rolled up the flaws. Alternatively it is also possible to provide the drum with a storage element or memory which contains the corresponding position data of the paper faults, for example by an electronic tablet arranged in the drum. In the pre-furling the drum paper web l is removed and then by means of a first cylinder d deviation 2 and a second deviation cylinder 3 is guided. The paper web itself is represented in the drawing with the reference figure 4. Between the drum 1 and the deflection cylinder 2 s there is a detector 5., which is built in its pickup characteristic as another detector integrated in the pre-positioned paper machine. While the other detects only is equipped to signal faults with a high speed of the band, and in reference to the length of the band give at least a rough location, the detector arranged in the pre-furling is equipped to recognize the fault of paper and pre-detected its exact character as well as the size and extent of the paper failure. In addition, a sensitization towards other qualities of paper failure can be provided, for example to recognize, clear and / or dark shadows or elevations or folds. In view of the values of the measurement of the detector 5, it is decided in the interior of the system, in what scope and in what manner the elimination of the fault is carried out. Since the rough location of the paper fault is known by reason of the results, the speed of the band section containing the paper fault can be decreased, even before it reaches that section of band to detector 5, to a value less than the normal speed. This has the advantage that the detector 5 is already prepared to meet and the approximate location of the signals d fails and will be prepared and will determine without delay the detail of the fault. The moment of encounter of the band section that presents the pre-detected paper fault with the detector 5 can as long as the paper web arrives directly without interruption of the paper machine to the pre-furling also calculated by means of the speed of the paper strip in the path of the other detector to the detector 5. The elimination of the paper fault is made in a station 6, which is found in the exemplary embodiment between the deviating roller 2 and the deviating roller 3 There is a sprayer 7 directed to the paper web 4, to sprinkle on the fault site, a UV lacquer with quick hardening. Alternatively, a fluid application can also be carried out by means of rollers. The application can be as represented in the drawings, performed on one side or on both sides. Alternatively it is possible instead of a lacquer U to use a plastic additive. It is important that the fluid by itself present the property of covering the place d fails in a flat way and forming a film, and in this way the paper in the area of the paper failure, for the following elaboration, can be protected for the stretch machine or pressure machine. The agent used must be able, in the process of forming the paper solution, for example in recycling or revaluation of old paper, easily separated from the paper. The application of fluid in station 6 was performed automatically, that is, without human activity. For this it must be known exactly, when the band section with the fall reaches the working area of the sprayer 7. For this the measurement of the speed is decisive with which the paper band moves and with this also the band section with the fault s moves from the detectors to the sprinkler, for this it is obtained calculates the speed of the paper band between the detector and the station 6 distanced later from the detector 6, by means of the speed obtained the exact moment is calculated in which the band section containing the fault s will find in station 6. Within the control of the sprinkler is also the result of the observations on the measurements made by the detector 5, this is the spray works not in all cases especially the width of the paper band, but only in the area that with respect to the direction of band length as well as with respect to the width d band has been detected as a defective area. Spray 7 as a combination of several individual sprinklers, which are controllable are arranged across the width of the paper web. Even before the arrival of the band section with the failure to station 6, the speed is decreased to a value less than the normal speed or, if necessary, to zero. After the station 6 has been run and the drying process can be considered as finished, the speed of the paper web is again raised to the normal value. In the drawing, a method for an application of "out of 1-line" is represented, that is, the other detector is already in the paper machine and station 6 as well as the detector are arranged in the pre-furler. However, it is also possible to apply the on-line procedure, where the station, the detector and the other detector will be found along the path of the paper, approximately on a combined papermaking and stretching machine. The detectors work optically throughout the width of the paper web. For practice, infrared detectors or CCD line cameras can be used.

REFERENCE LIST 1 DRUM 2 DEVIATION ROLLER 3 DEFLECTION ROLLER 4 PAPER BAND 5 DETECTOR 6 STATION 7 SPRAYER It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers-

Claims (3)

1. CLAIMS Having described the invention as above, property is claimed as contained in the following: 1.- Procedure for the automatic elimination of faults in paper during the manufacture of paper in a paper machine with the following steps: a) recognition, location and capture of the failure in the paper by means of a detector directed to the paper web; b) capturing or calculating the paper speed between the detector and a station connected farther away from the detector for the elimination of the fault. c) by means of the speed of the band of paper calculate the moment of the arrival of the section of band that presents the failure in the paper to the station for the elimination of the failure; d) automatic elimination of paper failure in the station for the elimination of the fault.
2. 2. Method according to claim 1 characterized in that, the moment of arrival of the band section that presents the fault in the predefined paper s calculates in the detector by means of the speed of the paper band on its way to the detector.
3. 3. Method according to claim 2 characterized in that the speed of the band section that presents the paper fault still before the band section reaches the detector is decreased to a value less than the normal speed. . - Method according to claim 3 characterized in that the speed already diminished immediately before the band section arrives at the station to remove the faults is decreased to a still lower value or to a null value. 5. Method according to one of the preceding claims, characterized in that the elimination of the failure in the paper is carried out by a flat covering of the failure place with a fast hardening fluid. 6. Process according to claim 5 characterized in that the fluid is sprayed on one side through both sides of the fault location. 7. Method according to claim 5 characterized in that the fluid is applied by a roller d application on the fault location 8. Process according to claim 5 or 7, characterized in that a UV lac is used as a fluid. of fast hardening.