US3547775A - Means and method for modulating fiber stock flow in papermaking headbox in response to paper sheet product parameters - Google Patents

Means and method for modulating fiber stock flow in papermaking headbox in response to paper sheet product parameters Download PDF

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US3547775A
US3547775A US547096A US3547775DA US3547775A US 3547775 A US3547775 A US 3547775A US 547096 A US547096 A US 547096A US 3547775D A US3547775D A US 3547775DA US 3547775 A US3547775 A US 3547775A
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sheet
flow
stock
slurry
moisture
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David A Bossen
Edward J Freeh
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Industrial Nucleonics Corp
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Industrial Nucleonics Corp
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/02—Head boxes of Fourdrinier machines
    • D21F1/022—Means for injecting material into flow within the headbox
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/06—Regulating pulp flow
    • 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
    • Y10S162/06—Moisture and basic weight
    • 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 upper surface of the stock may be contacted with a layer of dilute liquid which then effects the moisture content of the formed paper sheet.
  • the flow consistency may be modulated by regulating the addition of either dilute liquid or fiber stock to the flowing ⁇ stock prior to exiting the orifice which ultimately affects the basis weight of the formed paper sheet.
  • the flow modulation is controlled in response to controller means which include scanning moisture gauges and scanning basis weight gauges.
  • This invention relates generally to product manufacturing apparatus, and more particularly, to a method and apparatus for controlling the general uniformity of product formed by adjustable members.
  • Thickness is controlled by altering the flow of stock before it enters the headbox with an adjustable flow of white water (diluted stock).
  • a common conduit carries the white water stock mixture to the paper Inachine where it is subsequently delivered to the forming Wire or cylinder.
  • Uniform moisture content is provided by changing the amount of heat supplied to the dryer. With this type of control, there is an excessively long time lag between the point the stock flow is altered and the point it is deposited on the wire.
  • the present invention provides generally a method and means for quickly effecting a change in the weight per unit area of fibers deposited on the forming wire or cylinder.
  • the flow modification is hydrodynamic in nature and can be accomplished either by altering the consistency 0f the stock just before it leaves the headbox or by suppressing or throttling the How thereof at this point in the process.
  • fluid modulation of flow can be provided at a plurality of points across the width of the machine to obtain uniform fiber weight per unit area of the formed sheet in the cross-sheet direction, hereinafter referred to as profile, as well as in the machine direction.
  • a liquid such as water, diluted fiber stock or white water may be used to provide the desired mixing or suppression.
  • a source of white water is readily available and a conduit can supply a manifold communicating with the interior of the headbox upstream from the slice.
  • the manifold exits are open to the stock flow and individual valves are installed to change the rate of ow of white water into the headbox.
  • the local consistency of fiber content of the stock is altered by the mixing of the two flows occurring at each manifold exit.
  • the modified stream then fiows out through the slice opening and onto the wire.
  • the mechanical slice member is fixed and defines with the floor of the headbox an aperture providing for a given cross-sectional area of flow normally occupied by the fibrous slurry.
  • the liquid may be forced to flow generally in a layer adjacent to the stock and occupy a portion of the available headbox aperture cross-section.
  • the layer flow thus provided serves to regulate the weight per unit area of the formed sheet.
  • the layer flow of liquid may be injected either at the top or at the bottom of the fiber slurry flow. Control exerted in the region of the upper ow permits regulation of the moisture content of the sheet since the liquid must drain through the sheet. Thickness control of the lower flow permits regulation of the final sheet bone dry basis weight.
  • the layer flow technique is distinguished from the stock mixing technique described above in the relative degree of flow turbulence resulting from injection.
  • the moisture profile control system enables more moisture to be provided at the edges of the sheet than at the center to insure a uniform cross-sheet moisture content after it is dried in a dryer having a nonlinear drying rate.
  • our novel flow modulation techniques can be used in conjunction with a basis weight gauge positioned downstream from the headbox to measure and automatically control the weight per unit area Of the formed sheet.
  • a scanning gauge may be used for measuring the Weight per unit area of various cross-Sheet zones, the basis weight or, in the alternative fiber content, of each zone being determined by one of the several crossmachine fiow modulators.
  • the appropriate modulator is actuated to bring the basis weight of the sheet in its zone of control to the desired value.
  • the modulator control signal may be developed after each zone is scanned.
  • the gauge signal may be stored for purposes of a later correction in order to eliminate any short term transient effects that might result from immediate zone-by-Zone control.
  • the basis weight of the sheet is equal to the product of the thickness and the density of the sheet. Therefore, the terms basis weight and thickness may be used interchangeably when the density is relatively constant. This assumption may not be true for some paper-making processes. Since the modulators of the present invention primarily affect the fiber weight of the formed sheet, it may be preferred to measure the dry weight per unit area of the sheet and base control Accordingly, it is a primary object of the present invention to provide a product manufacturing machine having a faster speed of response than other devices of a similar nature.
  • FIG. l is a diagrammatic view of a paper-making machine comprising one preferred embodiment of the present invention.
  • FIG. 2 is a partial sectional view showing the construction of one type of flow modulator for use in the machine shown in FIG. 1;
  • FIG. 3 is a partial sectional view of an alternative construction for a flow modulator
  • FIG. 4 is a partial sectional view of another type of flow modulator
  • FIG. 5 is a partial sectional view of an improved modulator for a plastic extruder
  • FIG. 6 is a perspective view of a basis weight control system constructed in accordance with the present invention.
  • FIG. 7 is a partial sectional view, partially schematic, of a combined basis weight and moisture control system.
  • FIG. 8 is a sectional view taken on the line 8 8 of FIG. 7.
  • a typical paper-making line includes a machine chest 10 for storing the water-fiber slurry or stock that is deposited onto a traveling forming wire 12 to form the paper sheet 14.
  • the stock is frequently mixed by means of a valve 16 with a flow of white water prior to the headbox 18.
  • the mixture is pumped into the headbox 18 which has an exit slice lip 20 extending across the width of the forming wire 12. Excess water drains from the wire 12 and is later removed from the sheet 14 by rolls in a press section 22 and a dryer section 24.
  • a reel 26 winds up the dried paper sheet.
  • the hydraulic system includes an exit flow modulator 30 coupled to a hydraulic actuator 32.
  • a liquid supply unit 34 may include pumping equipment to maintain in the conduit 36 either a fixed volumetric flow rate or a given head or pressure.
  • the flow modulators coupling to the stock flow is illustrated by the dotted line 38 extending toward the lip 20 of the headbox.
  • the modulator 30 affects the distribution of the fibers being deposited on the wire 12 thereby altering the weight per unit area of the formed sheet 14.
  • the modulator 30 may affect the flow equally at all points across the face of the lip 20. Alternatively, it may be desired to produce a sheet heavier in some crosssheet areas than in others, or to otherwise increase the flexibility of thesystem, in which case, a plurality of individual modulators are provided, each affecting the flow across and through a small local region of the lip.
  • the stock flow in the headbox 18 is modulated upstream from the lip 20 at a point where the flow is relatively streamlined with little lateral mixing. The location of this point depends on the construction of the headbox.
  • a constant mass flow of fiber through each region produces a constant basis weight zone extending downstream in the machine direction toward the press and dryer sections 22 and 24.
  • Several of these zones, sideby-size, occupy the width of the sheet 12 and determine the profile or variations in the value of a physical variable of the sheet such as basis weight or moisture with distance across the sheet 14.
  • profile measurement and control will be taken up hereinafter; but, rst it is instructive to describe several types of preferred flow modulators. For simplicity, these descriptions are conlined to a single modulator operative to vary the sheet weight of only one zone.
  • FIG. 2 An enlarged view taken at a cross-section of the lip reveals a holey roll 40 positioned between the floor 42 and the The purpose of this embodiment is to alter the consistency of the stock stream 46 before it exits the lip opening 20a and is deposited onto the form wire 12. This may be accomplished by altering the flow in other streamline flow regions further upstream in the headbox 18. A change in consistency means, of course, that the mass flow of liber through the opening 20a will be altered. This alteration of ber mass flow is reflected by a corresponding change in the basis weight of the sheet being formed. Although many ways may be available to vary the stock consistency, one of the most convenient is to mix liquid ⁇ with the slurry to dilute the same.
  • White water may be pumped through a conduit 48 that terminates in the interior of theheadbox 18 preferably between the holey roll 40 and the lip opening 20a.
  • the flow of white water indicated by the single curvilinear arrows 50, commingles with the local stock flow 46.
  • An adjustable liquid flow regulator 52 may be provided in the conduit 48 to vary the amount of white water llowing per unit time into the headbox lip 20.
  • the flow regulator S2 may be manually adjustable by means of a knob 54 to Vary the consistency of stock delivered to the forming wire 12. For example, an increase in white water ow, lowers the stock consistency and decreases the weight of the sheet 14. Conversely, throttling of the white water ow increases the basis Weight of the sheet. Automatic control of the white Water ow will be described hereinafter.
  • FIGS. 3 and 4 illustrate only lnwo of several forms of suppression.
  • the total exit area of ow available to the local fiber stock flow 46 is throttled by movable diaphragm members actuated by white water or other fluid. This stock flow exit area is proportional to the height of the opening indicated by the thickness dimension tf of fiber slurry laid on the wire.
  • a valve such as a flexible stainless steel cover 56 is positioned over the open end of the conduit 48.
  • the rear of the cover 56 is fastened to the floor 42 of the headbox 18 away from the lip opening 20a.
  • White water 50 owing into the headbox, strikes the steel valve 56 deecting it upwardly in accordance with the pressure in the conduit 48.
  • a laminar ow of white water 50 deflected by the valve 56 is provided beneath the local stock flow 46 and occupies a portion of the total lip opening 20a proportional to the thickness t1 of the white water layer.
  • the weight of the sheet 14 is increased by reducing the mass flow of white Water owing into the headbox.
  • the valve 56 lowers and permits an increase in the flow of liber out through the lip opening 20a.
  • the underlying layer of white water quickly drains through the wire 12 and is collected and recirculated. The remaining iibrous sheet travels on to be dried more completely.
  • FIG. 4 Another flow suppression embodiment is shown in FIG. 4.
  • a deformable elastic membrane 60 completely encloses the end of conduit 48. No white water is pei'- mitted to ow but a force is conveyed by the enclosed liquid column and directed against the membrane 60 to project more or less of its outer surface into the path of the fiber stock 46 flowing toward the lip opening 20a.
  • a pressure regulator 62 is made adjustable to vary the head or pressure of the liquid column provided in the closed system.
  • FIG. 5 shows a portion of an extruder housing 41 containing a supply of plastic material 43. Normally, the plastic material 43 is forced out of the extruder housing 41 through a pair of die members 45a and 4511.
  • the die may be either linear to provide a at sheet of plastic or circular as commonly employed on blown film lines. In either case, the die is normally adjustable at sections along its length by means of mechanical screws (not shown) capable of altering the gap thickness at the lip 47 of the die. This atfects the thickness of the extruded product.
  • H. E. Sponaugle entitled Automatic Profile Gauge Control reported at vol. 19, No. 6, June 1963 of the Society of Plastics Engineers Journal.
  • a fluid pressure system 51 may be used to provide a flow of fluid against the underside of the diaphragm 49 to force it upwardly against the flow of plastic.
  • the diaphragm 49 may be carried in a pair of slots 53 provided in one of the die members 45h.
  • a valve 55 controls the fluid pressure and thus the thickness of the extruded product.
  • a plurality of diaphragms can be provided along the length of the die to control the profile of the extruded sheet product.
  • a valve 55 is connected between the fluid pressure system 51 and each diaphragm and adjusted in accordance with the zone control techniques described hereinabove.
  • diaphragm constructions may be employed to provide the desired result.
  • an increase in white water pressure extends the membrane 60 upwardly, thereby constricting the stock ow from the lip opening 20a.
  • the ber thickness tf decreases causing a reduction in the weight per unit area of the sheet 14.
  • a basic weight increase can be accomplished by a reduction of the pressure in the conduit 48.
  • membranes of various materials, sizes and mounting position may be tried, depending on the weight and character of sheet being produced.
  • semi-porous membranes may be used, permitting a combination of both the stock consistency and the stock suppression techniques of the invention.
  • other variations of the hydraulic actuating system may be made to improve the operation of the system.
  • IMPROVED FIBER WIEGHT CONTROL SYSTEM With reference now to FIG. 6, several modulators can be positioned side-by-side across the width of the headbox 18 to produce a sheet 14 having a predetermined ber weight profile; frequently ber weight per unit area is termed bone dry basis weight.
  • Six modulators are shown for purposes of illustration. Each modulator controls the fiber ⁇ weight per unit area, i.e., bone dry basis weight, in one of the six zones #1-#6 defined by the dotted lines extending in the machine direction down the sheet 14.
  • apparatus associated with a particular zone will be identied with a subscript numeral indicative of that zone.
  • a manifold piping arrangement 64 may be employed to convey the white Water to the several local cross-sheet regions of the lip 20.
  • the ow modulators are shown communicating with the upper surface 44 of the lip 20 for convenience of illustration.
  • a separate -valve 661-666 serves to regulate the mass flow of white water into each local lip region. Other ilow regulating devices may also
  • a traversing gauge 70 is employed to scan the sheet 14 laterally and provide on line 72 a signal proportional to the ber weight per unit area of the portion of the sheet being scanned.
  • a measuring circuit 74 amplities this signal and transmits it to an error signal detector 76.
  • Detector 76 develops a signal whenever the measured weight and the desired weight differ.
  • Controller 78 causes actuation of an appropriate one of a bank of motors 80 each coupled to one of the lvalves 66 by means of an actuator selector unit 82.
  • a scanning programmer 84 causes the gauge 70 to scan across the sheet 14 and demands from the actuator selector 82 that the controller 78 be coupled to the appropriate motor in the bank 80 to insure that 'weight control is exerted on the zone being measured.
  • the cooperation between the programmer 84 and the guage 70 and the actuator selector 82 is indicated by the heavy dotted line 86.
  • the modulators can be controlled simultaneously by changing the programming and selection functions of units 84 and 82 respectively.
  • the gauge 70 may include any of the known sensors sensitive to basis weight such as those operating on the radiation absorption principle.
  • U.S. Pat. 2,790,945 issued to H. R. Chope and assigned to total the same assignee as the present invention describes a gauge of this type. Since the sheet 14 is eventually dried to a very low moisture content, it is usually desirable to maintain uniformity of the bone dry weight of the sheet. A total sheet weight measurement may have to be compensated for moisture (if it rvaries signicantly) to compute the dry weight and permit more accurate control of the fiber content by our improved modulators. It is appreciated that the total sheet basis weight is proportional to the dry basis ⁇ weight thereof only when the moisture content of the sheet remains invariant.
  • Gauge 70 would include preferably both a moisture sensor and a basis weight sensor and instrumentation providing for the moisture compensation of a total basis weight signal would be provided in measuring circuit 74.
  • Circuit 74 ⁇ would deliver an amplified signal proportional to the dry weight per unit area or dry basis weight of the sheet region being scanned.
  • the mounting location of the gauge is not critical; however, it is preferred to position the gauge as near as possible to the headbox 18 to shorten the time lag between the point of control and the point of measurement. Measurement of the sheet 14 as soon as possible after it leaves the forming wire 12 would provide a time lag of only a few seconds at the most. Of course, measurement after the dryer section 24 would eliminate the need for moisture compensation but the excessively long transport time may nullify the advantages afforded by the modulators quick response.
  • the gauge will measure an area of sheet substantially smaller than the width of the cross sheet zones, provision may be made to average the weight of the sheet across each zone.
  • the gauge 70 scans across Zone #l and the dry ⁇ weight of this area of the sheet 14 is computed.
  • the gauge signal may be stored while the entire sheet is scanned.
  • the stored signal may be drawn from storage and used to provide the desired zone-by-zone prole control. Alternatively, control for a given zone may be effected immediately after that area of the sheet is measured. If the computed dry weight is larger than it should be, controller 78 energizes motor 80, for a period of time proportional to the weight error.
  • Valve 661 is actuated to increase the ow of white water into the left-hand edge of the slice lip 20.
  • COMBINED MOISTURE AND FIBER WEIGHT CONTROL SYSTEM The present invention provides not only for ber prole weight control but also for moisture profile control of the sheet 14. This is of great benet in view of the nonlinear drying characteristics of most dryer sections. Dryers characteristically remove more water from the edges of the sheet than near the center. This means that the dried sheet will not have a uniform cross-sheet moisture content. Moreover, the sheet may be damaged by overdrying the edges in attempting to eliminate the wet center. An attempt has been made to correct this without success by skewing the press rolls.
  • FIGS. 7 and 8 illustrate this novel method of sheet moisture control.
  • the headbox construction is similar to that described above ⁇ with the exception that a vertically adjustable slice member is shown defining the exit llow area with the floor of the headbox 18 from which the fiber stock flows in a sheet layer 92.
  • the flow of white water through a conduit 94 communicating ⁇ with the roof of the headbox lip 20 is controlled by an adjustable valve 96.
  • the water is deposited on top of the liber stock in a layer 98, the thickness of which decreases with distance from the headbox because of drainage through the fiber stock layer 92.
  • a moisture gauge 100 measures the moisture content of the sheet before it enters the dryer section 24.
  • the type of moisture gauge used is not critical.
  • a moisture measurement and control unit 102 may be used to actuate the valve 96. i
  • valves may be provided across the width of the headbox lip to provide the desired moisture profile illustrated in FIG. 8.
  • the desired moisture prole of the sheet 14 prior to entering the dryer 24 is indicated by the crowned liquid layer 98.
  • the illustration is diagrammatic and is not necessarily the distribution of white water and fiber actually occurring in the sheet 14 at this point in the process.
  • the control unit 102 works against a dilferent desired or target moisture content for each zone #1-#6.
  • the target moisture for zone #2 may be several percent lower than that for zone #l and yet several percent higher than that set for zone #3 near the center of the sheet 14.
  • the prole will be symmetrical about the center of the sheet and the targets for zones #4, #5 and #6 may be substantially the same values set for zones #3, #'2, and #1, respectively.
  • valve control is coordinated with the scanning of the moisture gauge 100 in a manner similar to that described above in connection with FIG. 6 to insure that moisture control is exerted on the zone being measured.
  • simultaneous valve operation is an alternative mode of operation as in the case of bone dry basis Weight control.
  • Concomitant bone dry basis weight control may be employed by positioning a ber content measuring gauge 104 after the dryer 24. Little, if any, moisture compensation of the gauge 104 is required when it is located adjacent to the dried sheet.
  • a bone dry basis weight modulator 108 utilizes the output signal from the gauge 104 and control system 106 to vary the stock consistency of the ow exiting the lip 20.
  • the suppression methods of weight modulation described hereinabove also may be employed with substantially equal utility.
  • a coarse adjustment of bone dry basis weight may be provided by slice control unit 110 energizing a motor 112 mechanically coupled to the slice member 90 (see the Alexander patent, supra). This alternative is desirable should a correction be called for that may be beyond the capability of the hydraulic modulator 108. It may be apparent that any adjustment of either the slice member 90 or the flow consistency may alter the moisture content of the sheet 14 as well as the dry ber weight per unit area. Therefore, the cooperation of the two variable control systems, viz. bone dry basis weight and moisture, is evident and both are required for the most economical return derivable from profile leveling.
  • dry weight may be controlled by a slice adjustment alone or by regulation of a stock dilution valve located upstream from the headbox.
  • Product moisture content may be controlled by spraying water directly on the product in varying amounts or by regulating the humidity of the environment in which the product is produced.
  • the present invention provides a new method of papermaking whereby the bone dry basis weight and moisture of the sheet product are automatically regulated to reduce significantly the amount of undesirable footage product and to permit control within narrow limits. This results from the use of fast-acting hydraulic actuators modulating the flow of liber stock as it is deposited onto the forming member, whether it be a wire, cylinder or other type.
  • the present invention also provides a moisture profile control system to correct for the non-linear drying rates prevailing in different lateral regions of the dryer section. Simultaneous measurement and control of both the moisture and the ber weight is another important feature of our invention.
  • the method of claim 1 further including the steps of measuring the moisture content of the formed sheet product and controlling the iiow of the dilute liquid to the upper surface of the slurry in response to the measured moisture content to maintain a substantially predetermined moisture content in the formed sheet product.
  • the method of claim 1 further including the steps of measuring the fiber content of the formed sheet product, and controlling the flow of 'the dilute liquid to the lower surface of the slurry in response to the iiber content measurement to maintain the iiber content substantially at a predetermined value.
  • said slurry has a lower horizontal boundry layer and said flow is modulated by varying the mass flow rate of slurry passing through the slice by bringing said dilute liquid into substantial contact with only a surface of the slurry and directing said dilute liquid towards the slice, said measuring step including deriving a measurement of the dry weight in each of a plurality of zones across the width of the sheet, said error deriving step including deriving an error indication between a target value and measured dry weight in each of the zones, and said modulating step including responding to the error indication in each of the zones to control an actuator for the dilute liquid in each of a plurality of cross-sheet regions corresponding with the cross-sheet zones to achieve a desired sheet dry weight in each of lthe regions.
  • modulating step includes varying the consistency of the slurry passing through the slice by commingling the dilute liquid with the slurry.
  • the modulating step includes varying the consistency of the slurry passing through the slice by commingling the dilute liquid with the slurry, said measuring step including deriving a measurement of the dry weight in each of a plurality of zones across the Width of the sheet, said error deriving step including deriving an error indication between a target value and measured dry weight in each of the zones, and said modulating step including responding to the error indication in each of the zones to control an actuator for the dilute liquid in each of a plurality of crosssheet regions corresponding with the cross-sheet zones to achieve the target dry weight in each of the zones.
  • said measuring step includes deriving a measurement of the dry weight in each of a plurality of-zones across the width of the sheet, said error deriving step including deriving an error indication between a target value and measured dry weight in each of the zones, and said modulating step includes responding to the error indication in each of the zones to control an actuator for the dilute liquid in each of a plurality of cross-sheet regons corresponding with the cross-sheet zones to achieve the target dry weight in each of the zones.
  • the method of controlling the moisture content of a paper sheet formed by depositing a slurry of ber stock owing through an aperture of a headbox onto a moving forming member, said headbox including a deocculating roller comprising the steps of: measuring the moisture content of said formed sheet, responding to the measured moisture content and a moisture target Value to derive a moisture error indication, and injecting a flow of a liquid dilute relative to the slurry between the roller and aperture into contact with the upper surface of said slurry while the slurry is within the headbox, and controlling the flow rate of lthe dilute liquid in response to the moisture error indication to maintain the measured moisture content of said sheet at the target value.
  • the method of claim 12 which further includes the step of selectively controlling said liquid flow at each of several regions across said aperture to provide a sheet having a predetermined moisture profile characteristic.
  • the method of controlling the uniformity of a paper sheet formed by depositing ber stock flowing through an aperture onto a moving forming member, said stock flowing through the aperture having an upper surface comprising the steps of measuring the moisture content of the sheet, responding to measure moisture content and a moisture target value to derive a moisture error indication, controlling the injection flow of a dilute liquid adjacent the upper surface of said iber stock flow prior to the formation of the sheet in response to the moisture error indication to maintain the moisture content of said sheet at the moisture target value,
  • Control apparatus for a papermaking machine comprising:
  • a headbox for storing fiber stock and including a slice lip opening for delivering a local ilow of said stock onto a moving sheet-forming wire and a roll rotatably mounted in the path of said stock flowing toward said lip opening to prevent flocculation of said ber stock,
  • a dryer section having a non-linear cross-sheet drying characteristic whereby certain cross-sheet zones of said sheet are dried to a greater extent than others
  • separa-te means for each of said zones feeding a source of dilute stock of controllable amounts on to different cross-sheet zones of the upper surface of said stock flow to change the moisture content of said sheet in each of said zones, and
  • each of said modulating means for controlling each of said modulating means to provide a sheet having a moisture prole characteristic inversely related to the cross-sheet drying characteristic of said dryer section to provide a dried sheet having a uniform moisture profile.
  • Control apparatus as set forth in claim 15 which further includes means for simultaneously hydrodynamically controlling the local flow of said fiber stock to provide a sheet having a uniform bone dry basis weight.
  • Control apparatus as set forth in claim 15 which further includes gauge means for measuring the moisture content of said sheet to generate a control signal for said controlling means.
  • Control apparatus for a papermaking machine including a headbox for storing a slurry of ber stock and including aperture means for delivering a local flow of said slurry onto a moving sheet-forming wire and a roll rotatably mounted in the path of said slurry flowing toward said aperture means to prevent flocculation of said liber stock, said slurry having an upper surface while in the headbox, a dryer section having a nonlinear crosssheet drying characteristic whereby certain cross-sheet zones of said sheet are dried to a greater extent than others, the improvement comprising:
  • liquid feeding means positioned between said roll and aperture means for feeding a liquid dilute relative to the slurry onto the upper surface of the slurry to control the moisture content across said sheet to provide said sheet entering said dryer section with a moisture profile characteristic inversely related to said cross-sheet drying characteristic of said dryer section, said liquid feeding means including different actuators for the different cross-sheet zones, and
  • a headbox for storing fibrous stock including a slice lip opening for delivering a local flow of said stock onto a moving sheet-forming wire at least as wide as said slice lip opening and a rotatable member positioned in the path of said stock flowing to said slice lip opening to prevent flocculation of said slurry fibers,
  • said modulating means including:
  • a source of diluted stock and means for mixing a controllable proportion of said diluted stock with said local flow of fibrous stock.
  • gauge means scanning across said sheet formed by said wire to provide a control signal indicative of the variations in the dry weight of said sheet in each ⁇ cross-sheet zone corresponding to one of said local stock ow regions
  • control means responsive to said control signal for actuating each of said valve means. to vary the fiber content per unit area of said scanned cross-sheet zone.
  • a headbox feeding a slurry of fibrous material to a slice opening, said headbox having a Iiioor and including a defiocculating roller for slurry flowing to the outlet, means within the headbox immediately upstream of the outlet and downstream of the roller for modulating the flow of local slurry to said slice opening to control the consistency of fiber in liquid passing through the slice opening, and a wire downstream of the outlet for receiving the slurry emerging from the outlet for enabling liquid to be removed from the emerging slurry, the slurry emerging from the outlet and received by the wire having a bottom surface, said modulating means including means for feeding a liquid dilute relative to the slurry along the oor into substantial contact with the bottom surface of the slurry emerging from the outlet so that the slurry fed to the wire is bounded on said surface by said dilute liquid, means for measuring a parameter of the formed sheet product affected by the dilute liquid, means responsive to said measuring means to a target value for the parameter for deriving an error signal
  • the apparatus of claim 20 further including means for measuring the moisture content of the formed sheet product and means responsive to said measuring means for controlling the flow of the dilute liquid to the upper surface of the slurry.
  • the apparatus of claim 20 further including means for measuring the moisture and fiber content of the formed sheet product, and means responsive to the measured moisture and fiber content for controlling the ow of the dilute liquid to the upper and lower surfaces, respectively, of the slurry.
  • a headbox feeding a slurry of brous material to a slice opening, said headbox having a deiiocculating roller, means within the headbox immediately upstream of the slice and downstream of the roller for modulating the ow of local slurry to said slice opening to control the amount of fiber per unit volume of slurry passing through the opening, said modulating means including means for feeding a liquid dilute relative to the slurry into contact with the slurry, means for measuring the bone dry basis weight of the sheet product, means responsive to the bone dry basis weight measuring means and to a target Value for bone dry basis weight of the sheet product for deriving a bone dry basis weight error signal, and actuator means responsive to the bone dry basis weight for controlling the flow of the dilute liquid to the modulating means.
  • said modulating means includes means for varying the mass flow rate of slurry passing through the slice by bringing said dilute liquid into substantial contact with only the bottom surface of the slurry and for directing said dilute liquid towards the slice opening.
  • said modulating means includes means for varying the mass flow rate of slurry passing through the slice by bringing said dilute liquid into substantial contact with only a surface of the slurry and for directing said dilute liquid towards the slice opening, said measuring means including means for deriving a measurement of the bone dry basis weight in each of a plurality of zones across the width of the sheet, and said modulating means being responsive to an error signal for each of the zones derived in response to the measurement in each of the zones and a target value to vary the bone dry basis weight in each of a plurality of cross-sheet regions corresponding with the cross-sheet zones.
  • modulating means includes means for commingling the dilute liquid with the slurry to control the fiber consistency of the slurry passing through the slice.
  • said modulating means includes means for varying the mass flow rate of slurry passing through the slice by bringing said dilute liquid into substantial contact with only a surface of the slurry and for directing said dilute liquid towards the slice opening, said measuring means including means for deriving a measurement of the bone dry basis weight in each of a plurality of zones across the width of the sheet, and said modulating means being responsive to an error signal for each of the zones derived in response to the measurement in each of the zones and a target value to vary the bone dry basis weight in each of a plurality of cross-sheet regions corresponding with the cross-sheet zones.
  • measuring means includes means for deriving a measurement of the bone dry basis weight in each of a plurality of zones across the width of the sheet, and said modulating means being responsive to an error signal for each of the zones derived in response to the measurement in each of the zones to vary the bone dry basis weight in each of a plurality of cross-sheet regions corresponding with the cross-sheet zones.
  • a headbox having a deocculating roller feeding a slurry of fibrous material to an outlet of the headbox, said headbox having a floor, said slurry having 'a bottom surface, and means within the headbox immediately upstream of the outlet and downstream of the roller for modulating the flow of local slurry to said outlet to control the amount of fiber passing through the outlet
  • said modulating means including conduit means having an orifice for feeding a liquid dilute relative to the l slurry along the headbox floor into contact with the slurry, said modulating means further including means for bringing said dilute liquid into substantial contact With only the bottom surface of the slurry and for directing said dilute liquid towards the outlet to control the mass fiow rate of the slurry passing through the outlet, gauge means for sensing the dry Iweight of the sheet, means responsive to said gauge means and a target value for dry weight for deriving a dry Weight error signal, and means controlling said modulating means in response to
  • Control apparatus for a fibrous product manufacturing machine including a headbox for storing fibrous stock and having flow aperture means providing for a ow of said fibrous stock onto a product forming wire, said stock flowing through the aperture having an upper surface, said apparatus comprising:
  • gauge means positioned adjacent and responsive to the moisture content and basis 4Weight of said formed product to lprovide a first signal indicative of the moisture content of said formed product and a second signal indicative of the bone dry Weight of said formed product, means responsive to said first signal and a target value for moisture content for deriving a moisture eiror signal,
  • Control apparatus for papermaking machine including ⁇ a headbox for storing fibrous stock and having an aperture from which said stock llovvs onto a moving Wire to form a sheet, said apparatus comprising:
  • first gauge means positioned adjacent said formed sheet to provide a measurement signal proportional to the moisture content of said formed sheet
  • second gauge means positioned adjacent to said formed sheet to provide a measurement signal proportional to the dry IWeight per unit area of said formed sheet, first controller means responsive to said moisture measurement signal and a target value for sheet moisture for deriving a moisture error signal, first actuator means responsive to said moisture error signal for depositing a layer of dilute stock of controllable thickness on the upper surface of said stock flow in the region of said aperture to control the moisture content of said sheet approximately to the moisture target value,
  • Control apparatus for a fibrous product manufacturing machine including a headbox for storing fibrous stock and having an aperture from which said stock flows onto a moving Wire to form a sheet, said apparatus comprising:
  • gauge means positioned adjacent said formed sheet to provide a measurement signal indicative of the dry Weight per unit area thereof
  • actuator means responsive to said dry weight error signal for modulating the local flow of said fiber stock to said aperture to provide a sheet of uniform dry weight per unit area equal approximately to the target value
  • said modulating actuator means including:

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US547096A 1966-04-29 1966-04-29 Means and method for modulating fiber stock flow in papermaking headbox in response to paper sheet product parameters Expired - Lifetime US3547775A (en)

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Cited By (19)

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US3619360A (en) * 1968-12-17 1971-11-09 Beloit Corp Basis weight control system for a papermaking machine
US3853695A (en) * 1972-10-12 1974-12-10 S Back Entraining a liquid into a fiber slurry to accelerate it prior to discharge from a flow path onto a forming wire
US3853694A (en) * 1973-04-24 1974-12-10 Beloit Corp Paper machine flow channel with a flexible plate projecting into the flow stream to act as an oscillator
US3989085A (en) * 1975-06-02 1976-11-02 Westvaco Corporation Method and apparatus for leveling the cross-direction profile of stock slurry on a papermachine
US4885060A (en) * 1988-02-01 1989-12-05 Westvaco Corporation Papermachine headbox profiling bar with fluid discharge orifices along its length
US4888094A (en) * 1984-09-19 1989-12-19 Sulzer-Escher Wyss Gmbh Method of operating a headbox apparatus for a papermaking machine
US4909904A (en) * 1987-12-09 1990-03-20 J.M. Voith Gmbh Headbox for a paper machine with dilution feed lines before a turbulence generator
US4956050A (en) * 1988-03-28 1990-09-11 Velmet-Ahlstrom Inc. Method for attenuation of the machine direction pressure pulsations in the headbox in paper and board machines
US5000227A (en) * 1988-02-01 1991-03-19 Westvaco Corporation Pressurized fluid carrier conduit connection
US5011576A (en) * 1988-02-17 1991-04-30 J. M. Voith Gmbh Breast box nozzle for a paper machine
US5196091A (en) * 1991-10-29 1993-03-23 Beloit Technologies, Inc. Headbox apparatus with stock dilution conduits for basis weight control
US5298125A (en) * 1991-08-22 1994-03-29 Beloit Technologies, Inc. Fluid jet supported headbox
US6149770A (en) * 1998-04-14 2000-11-21 Honeywell-Measurex Corporation Underwire water weight turbulence sensor
US6322666B1 (en) * 1998-02-23 2001-11-27 Valmet Corporation Regulation system and method in a paper machine
US20060185811A1 (en) * 2005-02-22 2006-08-24 Werner-Marcus Schmidtke Machine for the production/processing of a material web and damping device
US7856737B2 (en) * 2007-08-28 2010-12-28 Mathews Company Apparatus and method for reducing a moisture content of an agricultural product
US20120227919A1 (en) * 2011-02-24 2012-09-13 Zhong Zhou Method for Preparing Aramid Paper and the Aramid Paper Obtained Therefrom
US20130213596A1 (en) * 2010-09-20 2013-08-22 Voith Patent Gmbh Method for regulating the formation of a fibrous web
US9481777B2 (en) 2012-03-30 2016-11-01 The Procter & Gamble Company Method of dewatering in a continuous high internal phase emulsion foam forming process

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DE2946778A1 (de) 1979-11-20 1981-05-21 Bruderhaus Maschinen Gmbh, 7410 Reutlingen Verfahren und vorrichtung zur beeinflussung der stoffdichte
DE3639823A1 (de) * 1986-11-21 1988-06-01 Voith Gmbh J M Stoffauflauf fuer papiermaschinen od.dgl.
DE3802298A1 (de) * 1987-06-09 1988-12-22 Peter G Mercer Verfahren und vorrichtung zum verbessern der homogenitaet der faserverteilung beim maschinellen herstellen einer faserstoffbahn
WO1995009271A1 (en) * 1993-09-29 1995-04-06 Beloit Technologies, Inc. A basis weight control apparatus

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US3092538A (en) * 1960-11-09 1963-06-04 Beloit Iron Works Method and apparatus for feeding stock to paper making machine
US3407114A (en) * 1965-01-04 1968-10-22 Paul F. Springuel Cross machine control in papermaking
US3413192A (en) * 1965-06-14 1968-11-26 St Regis Paper Co Automatic measuring and control apparatus for forming sheet material
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US2928464A (en) * 1957-01-01 1960-03-15 Albert E Reed And Company Ltd Adjustable slice for flow box
US2951007A (en) * 1957-06-06 1960-08-30 Paul R Lippke Method and device for regulating the moisture content of endless moving webs of fibrous material
US3000438A (en) * 1957-11-08 1961-09-19 Industrial Nucleonics Corp Measuring and controlling system
US3073153A (en) * 1960-01-19 1963-01-15 Alger L Petitjean Moisture measuring system
US3092538A (en) * 1960-11-09 1963-06-04 Beloit Iron Works Method and apparatus for feeding stock to paper making machine
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Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3619360A (en) * 1968-12-17 1971-11-09 Beloit Corp Basis weight control system for a papermaking machine
US3853695A (en) * 1972-10-12 1974-12-10 S Back Entraining a liquid into a fiber slurry to accelerate it prior to discharge from a flow path onto a forming wire
US3853694A (en) * 1973-04-24 1974-12-10 Beloit Corp Paper machine flow channel with a flexible plate projecting into the flow stream to act as an oscillator
US3989085A (en) * 1975-06-02 1976-11-02 Westvaco Corporation Method and apparatus for leveling the cross-direction profile of stock slurry on a papermachine
US4897158A (en) * 1984-09-19 1990-01-30 Sulzer-Escher Wyss Gmbh Headbox apparatus for a papermaking machine
US4888094A (en) * 1984-09-19 1989-12-19 Sulzer-Escher Wyss Gmbh Method of operating a headbox apparatus for a papermaking machine
US4898643A (en) * 1984-09-19 1990-02-06 Sulzer-Escher Wyss Gmbh Headbox control apparatus for a papermaking machine
US4909904A (en) * 1987-12-09 1990-03-20 J.M. Voith Gmbh Headbox for a paper machine with dilution feed lines before a turbulence generator
US5000227A (en) * 1988-02-01 1991-03-19 Westvaco Corporation Pressurized fluid carrier conduit connection
US4885060A (en) * 1988-02-01 1989-12-05 Westvaco Corporation Papermachine headbox profiling bar with fluid discharge orifices along its length
US5011576A (en) * 1988-02-17 1991-04-30 J. M. Voith Gmbh Breast box nozzle for a paper machine
US4956050A (en) * 1988-03-28 1990-09-11 Velmet-Ahlstrom Inc. Method for attenuation of the machine direction pressure pulsations in the headbox in paper and board machines
US5298125A (en) * 1991-08-22 1994-03-29 Beloit Technologies, Inc. Fluid jet supported headbox
US5196091A (en) * 1991-10-29 1993-03-23 Beloit Technologies, Inc. Headbox apparatus with stock dilution conduits for basis weight control
US6322666B1 (en) * 1998-02-23 2001-11-27 Valmet Corporation Regulation system and method in a paper machine
US6149770A (en) * 1998-04-14 2000-11-21 Honeywell-Measurex Corporation Underwire water weight turbulence sensor
US20060185811A1 (en) * 2005-02-22 2006-08-24 Werner-Marcus Schmidtke Machine for the production/processing of a material web and damping device
US7531064B2 (en) * 2005-02-22 2009-05-12 Voith Patent Gmbh Machine for the production/processing of a material web and damping device
US7856737B2 (en) * 2007-08-28 2010-12-28 Mathews Company Apparatus and method for reducing a moisture content of an agricultural product
US20130213596A1 (en) * 2010-09-20 2013-08-22 Voith Patent Gmbh Method for regulating the formation of a fibrous web
US9096973B2 (en) * 2010-09-20 2015-08-04 Voith Patent Gmbh Method for regulating the formation of a fibrous web
US20120227919A1 (en) * 2011-02-24 2012-09-13 Zhong Zhou Method for Preparing Aramid Paper and the Aramid Paper Obtained Therefrom
US8444813B2 (en) * 2011-02-24 2013-05-21 Zhou ZHONG Method for preparing aramid paper and the aramid paper obtained therefrom
US9481777B2 (en) 2012-03-30 2016-11-01 The Procter & Gamble Company Method of dewatering in a continuous high internal phase emulsion foam forming process
US9809693B2 (en) 2012-03-30 2017-11-07 The Procter & Gamble Company Method of dewatering in a continuous high internal phase emulsion foam forming process

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Publication number Publication date
GB1192233A (en) 1970-05-20
GB1192231A (en) 1970-05-20
DE1561663A1 (de) 1970-04-02
GB1192232A (en) 1970-05-20

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