DE1648351A1 - Method and device for finding defects in a moving paper web or the like. - Google Patents

Description

Patent attorneys' ~

DIpI. log. F. Weiskn: c! Nii _ä Dr. In". Λ. ! ^! fenn 1648351

Df?!. Ing.HS-sicfensnn, Q _:? 3. Ti, ^. ZrAljtzko

£ wiinshen 27, Köiifötiaöa 22

Beloit Corp., 1, St. Lawrence Avenue, Beloit,

Wisconsin 53511, U.S.A.

Method and device for locating imperfections in a moving paper web or the like.

The invention relates generally to a method and an apparatus for finding flaws in a moving paper web or a moving web made of other material; more precisely The invention relates to a method and a device for Finding differences in the properties of a moving paper web and triggering a series of corrective measures, in which the movement of the paper web is not interrupted.

When making paper, there can be different in the finished paper web Defects occur that are not only undesirable, but also make the further stages of production more difficult can. In particular, errors in the paper web during these further manufacturing stages can cause the paper web to tear lead, if the paper web tears, the paper

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machine must be shut down and measures must be initiated in order to guide the beginning of the torn off track section into the following processing station of the machine. Very often however, these measures cannot be taken immediately, and. then the paper following the tear point begins to push itself together.

Most often the paper web maintains in the area of the doctor blade of the coating machine in the paper machine plant. In the coating machine, the paper web intervenes two rollers through, one of which is partially immersed in the coating compound, while the other applies the necessary counter pressure in brings about the nip formed together with the applicator roller. The applicator roller is in one containing the coating shaft Mass box stored, it is generally under spring pressure and is against the back pressure roller and the between out of the paper web running through both rollers. Since it is usually necessary to coat both sides of the paper web, two coating machines are connected in series. Each coating machine has a doctor blade with which to remove excess Coating compound is stripped from the paper web. The doctor blade is under spring pressure and is guided in such a way that that a predetermined layer thickness of the coating composition remains on the paper web.

Very often the paper web tears in the area of the doctor blade caused directly by material thickening, foreign bodies, holes, wet spots and other paper defects in the web.

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gently, which are already present before entering the coating machine. Since the scraper knife, which is under spring pressure, scrapes along the web, there may be flaws on the knife edge caught and cause the paper web to tear. When a crack occurs, the cracked part generally cannot get over the Slide away the knife edge so that the crack then spreads over spreads the entire width of the web. The paper web is now immediately pushed together in the area of the coating machine, and the Paper machine must be stopped immediately; the collapsed paper mass must be removed and thrown away.

It is therefore important to develop a method and an apparatus by which the number of such malfunctions caused by tearing of the web on the doctor blade, caused by defects in the paper web, is decreased. This method and this device are intended to ensure uninterrupted operation of the paper machine as far as possible guarantee and thereby the loss of manufacturing side switch off during papermaking.

The invention is therefore intended to provide a device which finds and flaws in a moving paper web initiates corrective measures in the paper machine in connection with this.

The flaws are presented at a station in the direction of travel

^ erfa SST an arrangement for equipping the PapiersVdürch the occurrence of voids is this equipment arrangement during the passage of the erroneous track sections and for some time thereafter put out of operation, and thereafter, this arrangement again

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put into operation and thus the continuous operation of the Paper machine not interrupted. Therefore, when finding flaws, the coating machine while running through the defective Track section switched off and also the associated one Stripping knife taken from the area of the paper web. At the same time, the defective area is marked on the paper web.

The invention provides a method with which the tearing of paper webs can be avoided in a paper machine without disrupting the continuous operation of the machine will. An essential feature of the invention is a circuit for averaging which is connected to a fault indicator and supplies a comparison signal which changes with changes in the reference weight of the paper web.

Further features and advantages of the invention emerge in detail from the following description with reference to the drawings showing the following:

1: a block diagram of an embodiment of an arrangement for finding flaws according to the invention;

2: a block diagram of a further embodiment of a Arrangement for flaw detection according to the invention;

3: a simplified block diagram for a comparison circuit, as it is used in connection with the arrangement according to Figure 2;

Fig. 4-: a simplified block diagram of a sequence control circuit for use in the arrangements according to Figures 1 and 2;

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FIG. 5: a simplified block diagram of a device according to the invention built-up circle for measured value processing.

Figure 1 shows an _e From guide Forin a fiction, according en arrangement for flaw detection. A web 11 is fed to a coating machine 12 via suitable rollers (not shown) which are not the subject of the invention. After leaving the coating machine 12, the web is fed to a second coating machine 13 via suitable rollers.

Certain types of paper require a coating on one or both sides of the web, depending on the particular use of the paper. In the embodiment shown here, the coating machine 12 is used to coat the one Side of the web 11, the machine 13 for coating the other side of the web. Both coating machines 12 and 13 have roller arrangements, which coating mass take up and apply it to the paper web passing through between the rollers; such arrangements are known per se. The coating machines 12 and 13 also have (not shown) doctor blades that touch the continuous paper web 11 and wipe off excess coating mass from the web.

A light source 16 is arranged above the track 11 in a suitable manner, not shown in detail. A photosensitive one Receiving element 17 lies opposite the light source 16, while the web 11 runs between the two} the light receiver receives the light transmitted by the web 11. The amount

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the light energy captured by the light receiver 17 is a measure of the density or strength of that part of the web 11 which is just between the light source 16 and the receiver 17 runs through.

The light source 16 stands for a plurality of light sources which are arranged distributed over the entire width of the web 11 can be, and accordingly, instead of a single light receiver 17, a series of light receivers via the Web width be provided distributed.

Should the part of the web 11 passing through between the light source 16 and the light receiver 17 have holes or relatively be thin, the light receiver 17 records a larger amount of light energy passing through. When the light receiver 17 detects a predetermined amount of light energy, a signal is generated and fed to a sampling relay 18. The level, in which the light receiver 17 emits such an excitation signal, is determined by an adjusting device 20 which is connected to the light receiver 17. The adjusting device 20 can automatically or manually adjustable, depending on the system in which it is used.

The touch relay 18 actuates a sequence st your circuit 21, the is equipped with suitable program and delay elements in order to trigger the necessary successive processes can. The follow-up circuit can either be constructed with solid bodies or consist of switching motors and timers.

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One of the output signals of the sequential control circuit 21 goes to a web marking control 23, which is assigned to the coating machines 13 and 13, and identifies the defective section of the web 11. Furthermore, the sequential control circuit supplies a signal to a control arrangement 24 for the coating roller and mass box, whereby the coating rollers of the die Coating machine passing web is lifted or the mass box with the coating mass is lowered, depending on what is simpler or more expedient to perform. A further output signal of the sequence control circuit 21 runs to the knife control 25, which guides the knives in the coating machines 12 and 13 away from the web 11 so that the defective sections of the web are not touched by a knife. Finally, a signal from the sequence control circuit 21 is sent to a timer or web length counter 26. The web length counter 26 causes a predetermined length of web 11 is 12 and 13 passes through the Sfceichmaschinen, whereupon given from the counter 26 an output signal which is operated by the sequence control circuit dam 29th This allows a sufficiently large piece of the web 11 to pass through the coating machines 12 and 13 so that the defective portion of the web 11 is not coated and does not come into contact with the doctor blade.

After the intended web length has passed the coating machines 12 and 13, the timer or web length counter 26 outputs a signal to the sequence control circuit 29, whereupon this sends a return signal to the counter 26 via a line 30, by which it is stopped or postponed as required.

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The sequence control circuit 29 provides several output signals, which switch the components of the coating machines 12 and 13 so that the continuous paper web 11 is coated. An output signal of the sequence control circuit 29 runs to the Knife control 31, as a result of which the doctor knife is operated in such a way that it moves the web 11 passing through the coating machines 12 and 13 touched. Another signal from the sequence control circuit 29 reaches a control 32 for the mass box and coating roller, whereby the mass box or the roller or both are raised so far that the coating mass on the coaters and 13 passing web 11 is applied. Finally, an output signal from the follower is sent to a circuit 29 Bahnmarkie approximately control 33 given, whereby the marking of the defective portion of the web 11 is terminated. That on the control signal given to the web marker control 33 is running also via a reset line 35 to the sampling relay 18 and brings this relay into the switch-off position. So that will Sampling relay 18 and the sequence control circuit 21 brought into readiness to be energized recently, provided that it is on again defective portion of the web 11 between the light source 16 and the light receiver 17 passes through.

Accordingly, aids are provided in the arrangement according to the invention for detecting FeHstellen that the change in Detect the build-up of the path 11 which passes between the light source 16 and the light receiver 17; one of the Changes in the track structure dependent control signal generated. That

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Control signal puts the coating machines 12 and 13 out of operation, so that the web 11 passing through during the passage the coating machines cannot be made to tear.

The signal supplied by the light receiver 17 is during operation the system used to control the sampling relay 18, which in turn initiates the sequence control circuit 21 to run. The sequence control circuit 21 then supplies four control signals: firstly, for actuating the web marking control 23, which identifies the web in the defect area, secondly, to actuate the control 24 for the coating roller and mass box, whereby the application of coating composition to the web 11 is canceled is, thirdly, to operate the doctor blade control 25, whereby the doctor blades in the coating machines 12 and 13 are lifted off the track running through the machines, and fourthly, to operate the timer or web length counter 26 which counts a predetermined length of the defective section the web 11 measures and then automatically actuates the sequence control circuit 29, which in turn sends a control signal back to the Counter 26 gives to stop and reset counter 26.

The sequence control circuit 29 provides several control signals: firstly to actuate the doctor blade control 31, through which the doctor blade in the two coating machines 12 and 13 be brought into contact with the web 11, which is watching the machines runs through, secondly, to actuate the control arrangement 32 for the compound box and the coating roller, both of which are raised to apply coating compound to the coating machines

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12 and 13 to apply continuous web 11, and thirdly to Actuation of the web marking control 33, whereby the marking of the web 11 is ended. The control signal given to the lane marker controller 33 is also processed in such a manner fed to the scanning relay 18 that the Heiais is reset and thus brought into the starting position in which it has recently been can be excited by the light receiver 17 if another defective section of the web 11 between the light source 16 and the light receiver 17 passes through.

In Figure 2 is a further embodiment carried out according to the invention an arrangement for detecting imperfections shown. A web 51 is fed to two coating machines 52 and 53, which Apply coating compound to web 51 during papermaking. On the way to the coating machines 52 and 53 the web 51 passes between a light source 56 and a light receiver 57. Light source 56 and light receiver 57 serve to detect irregularities and imperfections in the web 51 before such imperfections are reached by the coating machines 52 and reach 53. A data processing circuit 58 determines an average value from the light receiver 57 from the supplied signals and compares the average value with an instantaneous value that you also receive from the light receiver 57 is fed. If the instantaneous value of the signal fed to the data processing circuit 58 is sufficient differs from the mean value formed in circuit 58, a corresponding error signal is generated. This comparison device enables changes in weight to be compensated for It should be considered over a considerable length of the paper web.

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The error signal formed by the data processing circuit 58 is fed to a comparison circuit 59 in which the The error signal is compared to predetermined limit values that are set by the machinist by means of a comparison circuit 59 connected limit value control 60 entered can be. As soon as the error signal exceeds the limits specified by the limit value control 60, the Comparison circuit is given a signal to a sequence control circuit, which is thereby set in function.

The operation of the sequence control circuit 62 can essentially coincide with that of the sequence control circuit 21 according to FIG. The output of the sequence control circuit 62 leads to the Coating machines 52nd and 53 via line 63> to switch off of the coating machines 52 and 53 to initiate the necessary steps so that the defective portion of the web 51 is untreated passes through. The sequence control circuit 62 actuates the web marking device in detail, directs the lowering of A coating roller and mass box and lifts the doctor blades in the coating machines 52 and 53 from the web 51.

The length of the railway line traversed by the coating machines 52 and 53 during this period can be considered to be the faulty one Section of the railway can be viewed.

An adjusting device 68 sets the limit values of the timer or web length counter 67 to any given given Area. The output of the counter 67 comes in

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a sequence control circuit 70. Upon excitation of the sequence control circuit 70, a reset control signal is fed back into the timer or web length counter 67 via line 71, whereby the counter 67 is returned to the position in which it is again operated by the sequence control circuit 62 can.

The sequence control circuit 70 can be constructed in practically the same way as the sequence control circuit 29 according to FIG. Of the The output of the sequence control circuit 70 is given to the coating machines 52 and 53 via the line 72. Affected in detail the sequence control circuit first the doctor blade and guides it against the rollers of the machines 52 and 53 passing through Lane 51, it also lifts the roller and mass box group so far that the coating mass is brought onto the web 51 and finally it finishes applying marking paint or the like to the web 51 by the web marking device.

The data processing circuit 58 and the limit value control P 60 can be set individually by hand or, if required, by servo systems and assigned computing devices.

In Figure 3 is a simplified block diagram of the Comparison circuit 59 shown in FIG. 2 in an embodiment according to the invention. The comparison circuit 59 has a Amplifier 80 with input lines 81 and 82. The input 81 is connected to a voltage source via a potentiometer 85. The error signal of the data processing

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device 58 (FIG. 2) is applied to input 82. The amplifier 80 ″ is formed from the relative difference between the voltage fed to input 81 and that fed to input 82 Error signal then an output signal if the difference a predetermined one between the two signal inputs Value reached. The output value of the amplifier 80 is then fed to a relay winding 86 via a diode 87. To the Relay winding 86 includes a movable contact arm 88, which is used to initiate the function of the sequence control circuit 62 (Fig. 2) serves.

In Figure 4 is a block diagram of a simplified form Sequence control circuit (such as circuit 62) reproduced in an embodiment according to the invention. The output of the comparison circuit 59 is fed via a line 89 to a relay winding 90 which actuates a pair of contact arms 91 »92. From contact 91 from a line leads to a movement device for lowering the mass box and the coating roller as well as for introducing it the lane marking as described above.

The contact 92 provides a reference voltage to a timer 95 which is used to allow a suitable time interval to elapse between the lowering of the mass box and coating roller and the lowering of the doctor blade. The reference voltage supplied to the timer 95 can be changed by means of the potentiometer 96, which in turn allows the duration of the interval given by 95 to be varied. The output of the timer 95 is fed to an amplifier via a line 98

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directed. A reference voltage is also fed to the amplifier 97 via a potentiometer 99. The amplifier 97 can be designed as a differential amplifier by means of which the voltage difference between the input signal from the input line 98 and the reference voltage from the potentiometer 99 is detected. The output signal of the amplifier 97 is fed to the winding 100 of a relay via a diode 1o1. A contactor 102 is connected to the relay winding 100 and initiates the actuation of a device for lowering the doctor blade in the coating machine.

In Figure 5 is a block diagram of a simplified form Data processing circuit 58 in an embodiment according to the invention reproduced. The output of the light receiver 57 becomes inserted into the circle at point 105; there the signal is distributed over two lines. In the first branch the The information given to the signal is fed to a filter circuit 106 which converts the constantly changing signal into a signal with an average value reshaped. The input signal is fed to a summing analog circuit 107 via the other branch. That The output of the filter circuit 1O6 is also fed into the summing circuit 107 given. This analog circuit detects the changes between the average value of the input signal, as it is fed through the filter circuit 106, and the instantaneous values of the input signal s, as it is directly from the light receiver comes from. When a large variation in the input signal occurs, an error signal is generated in the analog circuit 107 formed and fed to the comparison circuit 59 (FIG. 2).

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Claims (1)

Patent claims 1. Method for detecting imperfections in a material web, the various processing stations of a processing system runs through, and to eliminate the influence of these defects on the operation of the processing system in a The processing station following the location of the detection of the defect, in particular to avoid tearing of the paper web in a paper machine and the interruption of the continuous Operation of the paper machine, characterized in that energy is sent to the material web from an energy source and that which takes place in the web Attenuation of the energy is determined, and that a signal is sent out at a predetermined amount of attenuation, which triggers control processes that the processing devices at the next or a further processing station put out of operation for a certain period of time, including the section of the path running through there during this period of time provided with a marking and then return the processing device at the respective station to the working position. 109885/0335 Af, . Arrangement for carrying out the method according to claim 1, characterized in that on one side of the web (11,51) an energy source (16,56) is provided which provides energy in accordance with defects occurring in the web material is weakened by the web, transmits through the web to an energy receiver (17 | 57) on the other side of the web is provided to collect the weakened energy from the web, and that an output signal of the energy receiver (17,57) Responding cut-off devices pick up an information signal that corresponds to a defect in the material web (11, 51), in order to initiate various control processes for the web processing devices, the shutdown devices are connected to the maintenance facilities that are linked to a suitable Signal to switch the web processing equipment on again speak to. > Arrangement according to claim 2, characterized in that the disconnection devices have a data processing circuit (58) for Averaging that from the detector (57) Signal included and a summing device (1o7) for adding an output signal of the detector (57) and a Output signal of an averaging circuit (1o6) for Averaging to form an error signal when a defect is detected in the web of material, whereby then the activity of the defeat devices is initiated. 109885/0335 Al 4. Arrangement according to claim 3, characterized in that the Disconnection devices have a data processing circuit (58) in which an averaging circuit (1o6) is included which averages the detector outputs and a summing device (1o7) for adding an output of the detector (57) to the output of the averaging circuit (1o6) to form an error signal when a defect is detected in the aterialbahn, and that a comparison circuit (59) is provided, one input (82) of which is connected to an output of the summing device (1o7) for comparing the Error signal with preset limit values, which are given by a voltage source of constant potential, which with a further input (81) of the comparison circuit (59) is connected to form a signal that the operation of the Preventive devices initiates. 5. Arrangement according to claim 2, characterized in that the energy receiver (17) generates a signal and sends it to a sampling relay (18) forwards, the level at which the receiver (17) delivers such a signal from an adjustment device (2o) is controlled for limit values, and wherein the sampling relay (18) actuates the cut-off devices and after the defective section of the web has moved past a predetermined length in its starting position will. 109885/0335 At 6. Arrangement according to the claims. 2 "to 5, characterized that the cut-off devices have a first sequence control circuit (21,62), which is a fault in the path supplies a corresponding signal to the web processing device turn off, and that the output of a in connection with the first sequence control circuit (21,62) and from this actuated counter (26,67) is in connection with a second sequence control circuit (29,7o), which is opposite to switching on the ) Counter (26,67) is delayed and the turns on again. 7 »Arrangement according to claim 6, characterized in that the switch-off devices for the web processing device, e.g. for coating machines, comprise a first web marking stowage (23) on the coating machines (12, 13) which is used to mark the faulty web section when an error occurs in the web (11) signal is connected to the first sequence control circuit (21), and that a second w web marker controller (33) which is connected to the second sequence control circuit (29) is energized when an appropriate signal is received to terminate the track marking . 8. Arrangement according to claims 2 to 7, characterized in that the disconnection devices have a first controller (24) for coating roller and mass box include those with the first Sequence control circuit (21) is connected to bring the coating machines (12,13) out of contact with the web when a 1Q988S / Q335 Defects in the material web (11) indicating signal recorded is, and that a second control (32) for coating roller and mass box connected to the second sequential control circuit (29) is connected, which brings the coating machines (12, 13) back into working position when a corresponding signal is received will. 9. Arrangement according to claims 2 to 8, characterized in that the disconnection devices have a first controller (25) for the doctor blade, which is connected to the first sequence control circuit (21) and the ground out of contact with the web if there is a defect in the web of material (11) indicating signal is received, and that a second control (31) for the doctor blade, which is connected to the second sequence control circuit (29) is connected, the knife returns to the working position when a corresponding signal is received. 109885/0335 Blank page