Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
  • D21G9/00—Other accessories for paper-making machines
  • D21G9/0009—Paper-making control systems
  • D21G9/0027—Paper-making control systems controlling the forming section
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S162/00—Paper making and fiber liberation
  • Y10S162/09—Uses for paper making sludge
  • Y10S162/10—Computer control of paper making variables
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S162/00—Paper making and fiber liberation
  • Y10S162/09—Uses for paper making sludge
  • Y10S162/10—Computer control of paper making variables
  • Y10S162/11—Wet end paper making variables

Definitions

• the invention relates to a method and a device for determining the effect of the adjustment of actuators according to the preambles of claims 1 and 19, and to a method for producing a material web according to the preamble of claim 22.
• the cross profile of the material web properties and the offset of the material web must be determined in order to be able to adjust certain actuators for setting a desired cross profile that are used in the production of the material web , are distributed over the web width and influence the material web properties.
• test tests to determine the local assignment of actuator positions to measuring positions on the paper web.
• test adjustments of individual actuators which are far enough apart with the aim of determining the locations and the geometric shape of the effects of these actuators on paper properties on the basis of transverse profile measurements.
• Such test adjustments are then carried out automatically, for example periodically or at the request of the operator, in order to recognize a changed process behavior.
• the test settings have to be chosen so large that the
• ERSATZBLAH (RULE 26)
• the result of the adjustment is clearly reflected in the paper and, after suitable measurement filtering, stands out from the process noise and measurement noise. So the tests disrupt the production process.
• the accuracy with which the places of action of the adjusted actuators are determined is determined by the number of cross-profile measurement values available or by the spacing of individual data values. This distance is usually 1 cm to 10 cm. In any case, the accuracy achieved is not sufficient to determine an exact cross-shrink cross-profile from the determined locations, as the following example calculation shows:
• the locations of the control elements are exactly known across the width of the production machine. Two actuators that are as far apart as possible are adjusted. The distance x ⁇ of these actuators is known. The distance between the profile changes x_ can be measured.
• the measuring task is to clarify, for example, the question at which point on the paper web the shrinkage is minimal, whether it is symmetrical, how the edges of the paper web behave in relation to the center, etc.
• the shrinkage must therefore be as small as possible be measured as precisely as possible on the paper web in order to obtain a meaningful cross-shrink cross profile.
• REPLACEMENT BLA ⁇ (RULE 26) is used, can be determined at any time in a simple manner without the need for the use of special marking devices or additional sensors which detect these markings. The production is not disturbed by test adjustments and by switching off any cross profile control that may be present. Due to the iterative procedure and the simultaneous consideration of many actuator adjustments and associated profile measurements, a much more precise local assignment of the actuator positions to positions on the material web is possible, so that a meaningful shrinkage curve can be determined.
• the mathematical determination of the impact is based on knowledge of the behavior of the material web properties.
• the computational determination of the effect is compared with actually measured values of a web property cross-profile obtained before and after an actuator adjustment in order to match the knowledge values in such a way that the computation results correspond as closely as possible with the measured results on the effect .
• An embodiment of the method is particularly preferred in which a prediction about the place of action of the actuator adjustment is made.
• This method is characterized in that it is relatively easy to carry out and to optimize.
• ERSATZBU ⁇ (RULE 26) Also preferred is a method which is characterized in that a prediction is made about the form of the impact, for example about the width of the impact at the point of action or the amplitude of the change in the material web properties at the point of impact. This procedure is also relatively easy to carry out and leads to the fact that the prediction of the place of impact can be optimized very well.
• a method is particularly preferred, in which actuators are taken into account which are used anyway for the production of the material web and are required for setting the transverse profile of the material web properties.
• a method of this type is characterized in that it does not require any additional devices or actuators which enlarge the installation space of the device for producing the material web, increase the construction and production costs and, if appropriate, also require additional maintenance.
• the ongoing production of the material web is not disturbed by an actuator adjustment, which is used only for measuring purposes. Current production remains unaffected.
• a method is particularly preferred in which the actuators are only adjusted as much as is necessary during production to correct the process faults by means of an automatic cross-profile control. Larger adjustments would disrupt production and reduce paper quality.
• REPLACEMENT BLA ⁇ (RULE 26)
• a method is preferred in which the predictions are modified step by step in such a way that first a general statement about the behavior of the material web properties is made, which is characterized in particular by the fact that it also produces a bad "noise to useful signal” Ratio "can still be made quickly with good accuracy.
• a simple statement could be, for example: The edges of the paper web are shifted by a certain amount compared to the position they should have in the machine at the measuring point if there was no shrinkage and no lateral run. Determine the two amounts of the shift smd.
• a first refinement of this statement would be, for example: the transverse shrinkage is stronger at the edges than in the middle and the resulting transverse shrinkage transverse profile has a bowl-shaped contour, the amplitude of which has to be determined.
• the prediction of the material web properties comprises determining the transverse shrinkage behavior as accurately as possible.
• REPLACEMENT BLA ⁇ (RULE 26)
• a method is particularly preferred in which the results are averaged when determining the cross-shrink cross-profile for a number of predictions and / or for a number of actuator adjustments. Such averaging means that the error in the mathematical determination of the impact is reduced to a minimum.
• the processing unit processes predictions or knowledge values about the behavior of the material web properties when adjusting an actuator and uses these knowledge values and by means of an assignment rule to determine the effect by calculation, it is possible at any time to determine the place where the change occurred Actuator is to be assigned to predict online and to determine an exact cross profile of a material web property and / or to determine a lateral offset of the web.
• FIG. 1 is a schematic block diagram of a device for determining the effect of actuators
• FIG. 2 shows diagrams for explaining the method for determining a cross profile
• FIG. 3 shows a schematic structure of a paper production machine
• FIG. 4 shows a two-layer headbox for producing a fibrous web with a schematically illustrated line system.
• various material web properties can be recorded, for example the weight per unit area, the moisture, the cross-hatch, the fiber layer, the roughness, the strength, the elasticity, the opacity, the smoothness, the filler content, the thickness, the formation.
• the measured values recorded across the width of the web are referred to as the transverse profile.
• a water-fiber suspension which may also include fillers, is introduced into a wire section (former) and that the fibrous web formed there, for example Paper web is fed over a press section dryer section.
• the auftoffaufauf can be designed so that actuators are provided to influence the material properties.
• ERSATZBU ⁇ (RULE 26) a so-called secondary material stream can be fed in, which consists, for example, of dilution water or a second type of paper material, but with a different, preferably lower, material density.
• the transverse distribution in the flow head is set by a plurality of sectional feed lines, each of which has a control valve referred to as an actuator.
• Mixing valves, referred to as actuators can in turn be provided when the water-fiber suspension is brought together with the secondary material flow.
• Actuators of the type mentioned here can also be provided at other points on the paper machine, for example in a steam blow box in the press or dryer section or in a post-treatment device, for example in a coating machine.
• FIG. 1 shows a device 1 for determining the effect of actuating element adjustments, which in addition serves to determine a cross-shrink cross profile and to determine the lateral path.
• the material web 3 is guided from left to right through the illustration in FIG. 1, which is indicated by an arrow.
• a headbox 5 is shown in broken lines on the left in FIG. 1 and has numerous actuators 7 distributed across the material web 3, only one of which is shown here. The others lie outside the representation level of FIG. 1.
• the actuators 7 are connected to a computing unit 11 via a control line 9. At a distance from the headbox 5, a
• ERSATZBU ⁇ (RULE 26) arbitrary place of the device for producing the material web 3, a measuring device 13 for determining web property cross-sections. This can be arranged, for example, at the end of a paper-making machine beyond the dryer section. However, it is also possible to provide several such measuring devices within the paper making machine.
• the measuring device 13 is connected to the computing unit 11 via a measuring line 15. Via an input line 17, additional information about the cross profile of the material web 3, which is dealt with below, can be input into the computing unit 11. The computing results of the computing unit 11 are output on an output line 19.
• FIG. 1 shows a schematic bar diagram 21, on the basis of which it is to be indicated that the various actuators 7 which are distributed across the material web 3 have different settings.
• a diagram 23 is shown schematically, which shows a measuring signal detected by the measuring device.
• different measurement signals result over the web width.
• the jagged line indicates that the measurement signal is heavily overlaid with measurement noise and process disturbances.
• ERSATZBU ⁇ (RULE 26) The relationship between the setting of different actuators 7 and the measurement signal in diagram 23 will be explained in more detail with reference to FIG. 2.
• FIG. 1 For this purpose, several diagrams are shown one above the other in FIG.
• An actuator 7/1 is located, for example, at a distance x 1 from this reference line 25 and here has a "positive” setting with a corresponding "width effect”.
• Another actuator 7/2 is at a distance x 2 from the reference line 25.
• a “negative” setting with a corresponding "width effect” of this actuator is assumed here purely by way of example.
• “Width effect” here denotes the width of the effect of the actuator adjustment at the point of action ".
• ERSATZBU ⁇ (RULE 26) Influenced actuator, set a locally increased moisture or a locally greater material thickness, which leads to a locally increased basis weight, also known as the basis weight.
• a reduced humidity or reduced material thickness would occur at a location which is assigned to this second actuator.
• curve a it is assumed in the context of a first prediction or first hypothesis based on knowledge values that the locations x 'corresponding to the setting of the actuators 7/1 and 7/2. and x ' 2 or positions of the answers or effects in the material web or paper web correspond exactly to the actuator positions x ⁇ and x-.
• the expected response positions or impact locations are therefore at a distance x '. or x * 2 from the reference line 25. This is indicated here by arrows.
• ERSATZBU ⁇ (RULE 26) supply of the cross profile, which is based on a change in the actuator 7/2.
• the reaction in the cross profile is shifted from the reference line 25 once to the right and once to the left.
• the shift of the reaction is here by ⁇ x. and ⁇ x. indicated.
• ERSATZBU ⁇ (RULE 26) initial knowledge values as well as for the rules for coordinating the knowledge values can be used a priori knowledge or can be entered into the computer.
• the knowledge values can be refined step by step in an advanced method step, for example by statements:
• the transverse shrinkage is stronger at the edges than in the middle and the resulting transverse shrinkage transverse profile has a bowl-shaped contour, the amplitude of which has to be determined.
• the transverse shrinkage occurs more strongly on one machine half than on the other.
• the size of the asymmetry factor is to be determined.
• ERSATZBU ⁇ (RULE 26)
• the actuator 7/1 or 7/2 is adjusted, the expected reaction in the transverse profile is calculated on the basis of a first prediction (see curve a).
• curve a for example, the prediction is made that the position of the answers in the cross-section takes place exactly at the locations that also correspond to the actuator positions. It can be seen that there is a deviation between the calculated value of curve a and the actual measured value of curve b, which is caused by the transverse shrinkage or lateral run of the web.
• ERSATZBU ⁇ differentiate, to test and to select the hypothesis with the best correspondence to the measurement signal shown in curve b.
• a refinement of the procedure consists in a priori knowledge, for example, of the shrinkage behavior and the fact that the course of the tooth is incorporated into the calculation of the hypotheses.
• the number of hypotheses to be examined can thereby be significantly reduced.
• Feed actuator 7, which is at a distance x 1 x ⁇ - ⁇ x- j _ from the reference line 25. It is therefore possible in a simple manner to assign a local material web property to an actuator and thus to take into account a transverse shrinkage or also a lateral course of the web.
• the method of correlation calculation has proven to be a particularly suitable calculation method for the mathematical determination of the degree of agreement of curves b and c. Another measure would be the mean square deviation of the two curves.
• ERSATZBU ⁇ (RULE 26)
• only those actuators are taken into account that are required for the usual ongoing adjustment of the cross profile.
• these can be actuators that influence the headbox.
• a control valve or a mixing valve can therefore be used as an actuator in the feed lines of the headbox.
• devices are used as actuators which, for example, can influence the heating output of the dryer section differently zone by zone over the web width.
• the method described here or the device for determining the effect of an actuator adjustment can be used in the same way in all cases.
• actuators can also be used which influence the weight per unit area, the moisture, the density or another property of the material or paper web.
• the choice of the predictions or hypotheses for determining the various curves in FIG. 2 is preferably carried out step by step.
• a prediction is made in which, on the one hand, only a few large values are to be determined and, on the other hand, a large number of manipulated values and profile measured values are available. This applies, for example, to a prediction of the total cross-shrinkage of the paper web and the location in the cross-section measured across the paper web, at which the change in an actuator is shown.
• ERSATZBU ⁇ (RULE 26) a reliable determination of the locations happens very quickly, even if the manipulated variables are very small compared to the process noise.
• ERSATZBU ⁇ (RULE 26) Cross profile determined with the aid of the computing unit 11 by comparing the predicted effect with the actually measured effect and using the deviations to modify the knowledge values until there is better or as good a match as possible between the predicted and the calculated effect results.
• ERSATZBU ⁇ (RULE 26) are determined, taking into account many actuator adjustments.
• the fact that a number of predictions and also a large number of actuating element adjustments are taken into account makes it possible to eliminate the measurement errors as far as possible, even if the amplitude of the actuating element adjustments is very small.
• the device shown in FIG. 1 has only one measuring device 13. It is also mög ⁇ Lich However, 'within a device manufacturing be ⁇ relationship as paper machine several measuring points -in Ford construction of the web as seen lying one behind the other to arrange. Then the cross
• ERSATZBU ⁇ (RULE 26) cross-shrink profile can be calculated at several points within the machine, so that conclusions can be drawn as to how the cross-shrinkage has changed between different measuring points.
• a further application of the invention consists in observing the influence of a special treatment of the material web in a suitable aftertreatment device, for example the sizing or rewetting of a paper web, on the cross-shrinkage on-line. Further process variables, for example the glue absorption of the paper, can then be derived from the shrinkage change. These process variables can then be used for the determination of further control interventions.
• ERSATZBU ⁇ (RULE 26) fil can be specifically changed by moistening the web locally.
• parameters influencing the shrinkage are, for example, production process parameters in the area of the wet part, the press, and the dryer section. Examples are: local temperature distribution of the paper web during the drying process, the moisture cross profile during the drying process or directly after the press, the fiber orientation, locally varying degrees of hindrance to the shrinking process by suitably differently strong fixing of the web in the web transverse direction. Other influencing factors are conceivable. Which influencing variables can be used practically will automatically emerge after a prolonged use of the presented method for the on-line measurement of the cross-shrink cross-profile.
• the actuators in particular the control valves, for setting the specific basis weight in large numbers are provided at a very short distance from one another. It is therefore extremely important to be able to predict precisely which actuator must be addressed in order to influence a local material web property. This is precisely possible with the method described here and the device shown in detail.
• ERSATZBU ⁇ (RULE 26) Possible applications of the invention are explained in more detail below with reference to FIGS. 3 and 4.
• FIG. 3 shows a papermaking machine 31 with a headbox 33, which is comparable to the headbox 5 according to FIG. 1.
• the papermaking machine 31 has a wire section 35, also referred to as a former, a press section 37 and a drying section 39.
• This is provided with at least one zone-controllable steam blower box 41, by means of which the cross profile of the material web 43, for example the dry content cross profile, can be influenced.
• the papermaking machine 31 also has a computing unit 45 which is comparable to the computing unit 11 shown in FIG. 1.
• the headbox 33 is connected to the arithmetic unit 45 via signal lines 47 and 49, via which, on the one hand, the actual position of various actuators of the headbox 33 can be detected and which, on the other hand, serve to forward control signals to the actuators.
• the papermaking machine 31 is also provided with a measuring device 51 which corresponds to the measuring device 13 shown in FIG. 1 and which outputs measurement signals to the computing unit 45 via a signal line 53.
• a measuring device 51 which corresponds to the measuring device 13 shown in FIG. 1 and which outputs measurement signals to the computing unit 45 via a signal line 53.
• This can be provided with a monitor 55 on which both measurement and control signals can be displayed.
• ERSATZBU ⁇ (RULE 26) It is clear from FIG. 3 that with the aid of the measuring device 51 transverse profiles of the material web 43 can be detected.
• a particularly important field of application of the invention is the so-called basis weight cross-section control, with the aid of which the most uniform possible surface-related mass distribution of the material web is to be set. If, with the help of the measuring device 51, deviations in the desired basis weight of the material web, i.e. deviations in the basis weight cross-section, are determined, certain actuators of the headbox 33 can be controlled via the computing unit 45 so that the desired thickness of the material web or the desired basis weight is set . It is therefore possible to locally influence the amount of fiber that is released via the headbox 33.
• the cross-section of a material web can be influenced in a targeted manner with the aid of the invention described here, because the local material web properties can be adjusted by a specific adjustment of various actuators, be it actuators in the headbox or in a steam blow box. can be influenced.
• ERSATZBU ⁇ (RULE 26) With reference to FIG. 4, the particularly important application of the invention is to be discussed once again, namely the basis weight cross profile control or the setting of a predetermined basis weight cross profile of a material web on a headbox.
• FIG. 4 shows, by way of example only, a two-layer headbox 33, together with a schematically illustrated line system for feeding various fiber suspensions.
• the headbox 33 comprises a nozzle 57, which is known to be delimited by two flow guide walls 57a and 57b which extend over the width of the papermaking machine 31.
• the current guide walls 57a, 57b are each connected to a central stationary partition 61 via a known turbulence generator 59.
• a lamella 65 is pivotally attached by means of a joint 63. Deviating from this, the lamella can also be rigidly attached to the partition 61.
• a first main material flow which consists of a first type of paper material, reaches a one of the two turbulence generators 59 via a transverse distribution line 67 and via a row of sectional supply lines 69 branched off from it.
• ERSATZBU ⁇ (RULE 26) an actuator designed as a volume flow controller can be provided.
• a second main material flow consisting of a different type of paper material, reaches the other turbulence generator via a transverse distribution line 71 and via a row of sectional feed lines 73 branched off from it.
• a third cross-distribution line 75 is provided, via which a so-called secondary material flow is fed.
• This consists, for example, of dilution water or a second type of paper stock, but with a different, preferably lower stock density.
• a plurality of sectional supply lines 77, each with an actuator designed as a control valve 79, are branched off from the transverse distribution line 75.
• Each of the supply lines 77 thus leads a controllable sectional secondary material flow to a mixing point 81, where it is mixed with one of the sectional main material flows.
• the line system 71 to 77 with the control valve 79 and the mixing points 81 will preferably be assigned to the middle layer.
• ERSATZBU ⁇ (RULE 26) nale secondary streams could open into the section feed lines 69 for the first main stream.
• the actuators can be arranged at a relatively short distance from one another. While in conventional types of a material casserole, the aperture adjustment of which is carried out in particular with adjusting spindles, the influence of the adjustment of an adjusting spindle on the surface weight cross-profile corresponds more than four times the actuator spacing, the adjustment of an adjusting element influencing the secondary material flow has an effect ⁇ links to the basis weight cross section approximately in the range of two and a half times the actuator distance.
• the overall result of the description is that the method for determining the effect of an actuator adjustment can be carried out easily, and that the process for producing a material web is in no way disturbed, in particular not all parts of the measurement based on the measurement
• the method is suitable, on the one hand, for predicting the place of action of an actuator adjustment, but also, on the other hand, for the course of the rail properties in the vicinity of the place of action, that is, for the form of the effect.
• the predictions about the form of the impact that is to say about the extent of the impact at the impact location and about the amplitude of the changes in the material web properties at the impact location, are gradually improved further by comparison with measured values.
• a superimposition of the effect of an actuator adjustment with the effects of adjacent actuator adjustments can be predicted. It can be seen, in particular, that the extent of the effect of the adjustment of an actuator is often so wide that it extends over several actuators.
• both a transverse shrink cross profile of a material web and the lateral course of the material web within the production machine can be exactly determined, according to what has been said above.
• ERSATZBU ⁇ (RULE 26) fil is of interest on the one hand as an important quality parameter of the web produced, on the other hand it also enables conclusions to be drawn about the function of the production machine.
• the effect can initially be roughly predicted on the basis of knowledge values and that when several spindles are adjusted and when determining the effect of the adjustments, the prediction about the effect can be coordinated in such a way that both a transverse shrinking transverse profile and lateral running of the web can be detected.
• an actuator determines the effect after each adjustment and is checked by measurement, an abundance of measured values is obtained, so that the knowledge values can be optimally coordinated.
• the large number of determinations of the effects can best be realized by automatically carrying out the method, so that finally an online determination of the effects is also possible.
• ERSATZBU ⁇ (RULE 26)
• a technological process assessment should be possible, for example, uniform drying over the web width in the dryer section or uniform fiber orientation in the wet section and a uniform longitudinal to transverse tensile strength ratio over the web width or the like.

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• Paper (AREA)
• Optical Recording Or Reproduction (AREA)
• Electrophonic Musical Instruments (AREA)
• Spectrometry And Color Measurement (AREA)
• Apparatus For Radiation Diagnosis (AREA)
• Controlling Rewinding, Feeding, Winding, Or Abnormalities Of Webs (AREA)

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• 1995
  • 1995-11-14 DE DE19542448A patent/DE19542448A1/de not_active Withdrawn
• 1996
  • 1996-10-25 EP EP96937230A patent/EP0803011B1/fr not_active Revoked
  • 1996-10-25 CA CA002210200A patent/CA2210200A1/fr not_active Abandoned
  • 1996-10-25 DE DE59606824T patent/DE59606824D1/de not_active Expired - Fee Related
  • 1996-10-25 WO PCT/EP1996/004639 patent/WO1997018349A1/fr not_active Application Discontinuation
  • 1996-10-25 AT AT96937230T patent/ATE200810T1/de not_active IP Right Cessation
  • 1996-10-25 US US08/860,833 patent/US6207017B1/en not_active Expired - Fee Related
• 1997
  • 1997-07-11 NO NO973248A patent/NO973248D0/no not_active Application Discontinuation

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