EP0147350B1 - Converflo trailing element - Google Patents

Converflo trailing element Download PDF

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Publication number
EP0147350B1
EP0147350B1 EP84630167A EP84630167A EP0147350B1 EP 0147350 B1 EP0147350 B1 EP 0147350B1 EP 84630167 A EP84630167 A EP 84630167A EP 84630167 A EP84630167 A EP 84630167A EP 0147350 B1 EP0147350 B1 EP 0147350B1
Authority
EP
European Patent Office
Prior art keywords
machine direction
headbox
cross
stiffness
trailing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP84630167A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0147350A3 (en
EP0147350A2 (en
Inventor
Jose Juan Antonio Rodal
James Leroy Ewald
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Beloit Technologies Inc
Original Assignee
Beloit Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Beloit Corp filed Critical Beloit Corp
Publication of EP0147350A2 publication Critical patent/EP0147350A2/en
Publication of EP0147350A3 publication Critical patent/EP0147350A3/en
Application granted granted Critical
Publication of EP0147350B1 publication Critical patent/EP0147350B1/en
Expired legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F5/00—Dryer section of machines for making continuous webs of paper
    • D21F5/02—Drying on cylinders
    • 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
    • D21F1/028—Details of the nozzle section
    • 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

Definitions

  • the invention relates to a headbox for delivering stock to a forming surface as defined in the pre-characterizing portion of claim 1.
  • Such a headbox is known from DE-A-2 142 533.
  • the trailing elements of this headbox have corrugations to generate turbulence in the stock flowing toward and through the slice opening. Due to the corrugations the trailing elements have a structural stiffness greater in the cross-machine direction than in the machine direction.
  • the material of which the trailing elements are formed is isotropic, i.e. it has the same properties in all directions.
  • a basic limitation in headbox design has been that the means for generating turbulence in fiber suspension in order to disperse the fibers have been only comparatively large-scale devices. With such devices, it is possible to develop small scale turbulence by increasing the intensity of turbulence generated. Thus, the turbulence energy is transferred naturally from large to small scales and the higher the intensity, the greater the rate of energy transfer and hence, the smaller the scales of turbulence sustained. However, a detrimental effect also ensued from this high intensity large-scale turbulence, namely, the large waves and free surface disturbance developed on the Fourdrinier table. Thus a general rule of headbox performance has been that the degree of dispersion and level of turbulence in the headbox discharge was closely correlated; the higher the turbulence, the better the dispersion.
  • a headbox design under this limiting condition then, one could choose at the extreme, either a design that produces a highly turbulent, well-dispersed discharge, or one that produces a low-turbulent, poorly dispersed discharge. Since either a very high level of turbulence or a very low level (and consequent poor dispersion) produces defects in sheet formation on the Fourdrinier machine, the art of the headbox design has consisted of making a suitable compromise between these two extremes. That is, a primary objective of the headbox design up to that time had been to generate a level of turbulence which was high enough for dispersion, but low enough to avoid free surface defects during the formation period.
  • the method by which the above is accomplished is to pass the fiber suspension through a system of parallel cross machine channels of uniform small size but large in percentage open area. Both of these conditions, uniform small channel size and large exit percentage open area, are necessary.
  • the largest scales of turbulence developed in the channel flow have the same order of size as the depth of the individual channels by maintaining the individual channel depth small, the resulting scale of turbulence will be small. It is necessary to have a large exit percentage open area to prevent the development of large scales of turbulence in the zone of discharge. That is, large solid areas between the channel's exits, would result in large-scale turbulence in the wake of these areas.
  • the flow channel must change from a large entrance to a small exit size. This change should occur over a substantial distance to allow time for the large-scale coarse flow disturbance generated in the wake of the entrance structure to be degraded to the small-scale turbulence desired.
  • the area between channels approaches the small dimension that it must have at the exit end. This concept of simultaneous convergence is an important concept of design of this invention.
  • the trailing members which are employed to obtain the fine scale turbulence are not necessarily stable.
  • Cross-machine transient pressures tend to bend the trailing element in the cross-machine direction and cause cross-machine uniformity variances in the paper.
  • Resistance to deformation along the machine direction length of the trailing elements can cause slight digressions in the uniform velocity of the stock flowing off the surfaces at the trailing edge of the trailing element.
  • Static or dynamic instability can occur at certain operating conditions and resonant frequencies can be reached dependent on the hydrodynamic forces. It has been discovered that the inertia and hydrodynamic couplings can be broken by suitable distribution of the mass and elasticity of the trailing structure with proper mass distribution and stiffness distribution being of importance.
  • the objectives are obtained by providing a trailing element in a headbox as defined in the pre-characterizing portion of claim 1, which trailing element is formed of a material having an anisotropic characteristic to provide for the greater structural stiffness in the cross-machine direction according to the characterizing portion of claim 1.
  • the trailing element is formed of a laminate with separate layers of the laminate providing the qualities of cross-machine stiffness and machine direction strength and flexibility by either material properties, direction, size or number. Alternates of woven or needled material with weave directions or materials, or size or numbers of filaments controlling directional stiffness.
  • the trailing element has a structural stiffness in the cross-machine direction greater than in the machine direction at its downstream portion.
  • design factors which are otherwise not always available can be included such as strength, stiffness, corrosion resistance, wear resistance, weight, fatigue life, thermal expansion or contraction, thermal insulation, thermal conductivity, acoustical insulation, damping of vibrations, buckling, low friction and optimal design in manufacture.
  • Figure 2 is a perspective view partially in section of a trailing element of the headbox of Figure 1.
  • a headbox 10 has papermaking stock 11 delivered thereto to flow through the headbox toward a slice chamber.
  • various arrangements are positioned upstream of the slice chamber to control the flow and turbulence of the stock.
  • the stock flows forwardly through openings in a wall 14 at the entry to the slice chamber.
  • Trailing elements 18 and 19, Figure 1A extend downstream in the slice chamber pivoted at their upper ends and free along their lengths and at their lower ends to be positionable solely due to forces of the stock flowing toward the slice opening 16.
  • the stock is emitted from the slice opening 16, it is delivered onto a travelling forming surface.
  • the trailing elements are pivotally mounted at their upstream ends, and the pivotal mounting is immediately followed by a bent or angular portion which permits a short portion of the trailing elements to extend at right angles to the wall 14 and because of the bend, the trailing elements immediately turn and extend in the direction of the slice chamber.
  • two outer trailing elements 18' extend substantially the length of the slice chamber, and an intermediate trailing element 19' is constructed of greater length to extend through and slightly beyond the slice opening.
  • the downstream ends of the trailing elements 18" and 19" are curved to substantially conform to the curvature of the slice chamber as shown in Figure 1C.
  • the upper trailing element 18' terminates short of the slice opening 16, whereas the lower trailing element 19" extends beyond the slice opening a short distance.
  • FIG 2 a form of trailing element 18'" is shown in detail.
  • the trailing element 18"' has outer layers 18a and 18b and a central integrally sandwiched intermediate layer 18c therebetween.
  • the upper end of the trailing element is pivotally supported in a wall 14' such as by an enlarged or bulbous ridge 24 at the upper end pivotally mounted in a slot 25 in the wall 14'.
  • Directional lines are shown with a machine direction line shown at the 90° axis and the cross-machine direction shown at the 0° axis and the intermediate direction shown by the double arrowed line with the angle between the double arrowed line and the machine direction line shown as a.
  • headboxes may be employed as will be recognized by those versed in the art, including such as shown schematically in the aforementioned patents, RE 28 269 and 3 939 037.
  • the trailing elements were formed of metal or plastic or woven and were isotropic in nature in the sense that the trailing element stiffness (Young's modulus) was the same in the flow and cross-flow direction.
  • the trailing elements which extend flat in a cross-flow direction either in separate strips or continuous from pondside to pondside can be a single layer or multilayered, flat or curved, (in the flow direction) uniform thickness, or tapered, thin or thick.
  • the material is anisotropic so as to have different strength and/or stiffness characteristics in different directions.
  • the anisotropic trailing elements have a greater stiffness in the cross-machine direction than in the machine direction. This being more important at the downstream tip of the trailing element.
  • the difference between the stiffness in a cross-machine direction and a machine direction is a minimum of 5% and preferred to be 500% or more.
  • the stiffness limit as designated by Young's modulus in the cross-machine direction is a maximum 689500 MPa (100 000 000 psi), and a minimum stiffness in the machine direction is 344,75 MPa (50 000 psi), due to existing materials properties.
  • the anisotropic trailing elements can be formed of a composite material, that is, a laminate wherein the different physical properties of the different layers can be taken advantage of.
  • the outer layers can be formed with cross-direction fibers of a material such as graphite, with the inner layer containing a weaker stiffness material oriented in the machine direction, such as fiberglass. This would give greater stiffness in the cross direction, and less stiffness in the machine direction due to material stiffness, and material position within the matrix.
  • the anisotropic trailing elements can be formed from composite materials such as graphite, kevlar, boron, glass, carbon, beryllium, steel, titanium, or aluminum fibers in matrices such as epoxy, polyamide, carbon, polyester, phenolic, silicone, alkyd, melamine, fluorocarbon, polycarbonate, acrylic, acetal, polypropylene, ABS copolymer, polysulfone, polyethylene, PEEK, polystyrene, PPS, nylon, thermoset, plastics, thermoplastics, glass, metal or other matrices. Different materials can be combined, not such as in alloying where the result is homogeneous, and isotropic.
  • matrices such as epoxy, polyamide, carbon, polyester, phenolic, silicone, alkyd, melamine, fluorocarbon, polycarbonate, acrylic, acetal, polypropylene, ABS copolymer, polysulfone, polyethylene, PEEK, polystyrene, PPS,
  • the advantage of a composite laminate is that it may attain the best qualities of the constituents and often qualities that neither alone possess. Tailoring of an anisotropic material yields not only the stiffness, strength, thermal expansion, thermal conductivity, acoustic insulation, fatigue and life required in a given direction, but functions in an improved manner during service of the headbox. The relative factors sought after are: strength, stiffness, thermal expansion, thermal conductivity and so forth. If an isotropic material were used, a compromise would have to be reached as to the material chosen. This compromise is not necessary in an anisotropic structure, wherein the desirable properties of different directions may be exploited. Outstanding mechanical properties can be combined with unique flexibility.
  • Properties that can be improved by using an anisotropic design are strength, stiffness, corrosion resistance, wear resistance, weight, fatigue, life, thermal expansion or contraction, thermal insulation, thermal conductivity, acoustical insulation, damping of vibrations, buckling, low friction and optimum design and manufacture.
  • inertia and hydrodynamic couplings can be broken by suitable distribution of the mass and elasticity of the structure with proper mass and stiffness distribution being of significant importance.
  • An anisotropic design can attain stability with improved function of the trailing elements.
  • trailing element While the structure is shown with the trailing elements being pivotally mounted at their upstream end, this is a preferred arrangement and other forms of mounting may be employed which need not be pivotal. It is important, however, that the trailing element be self-positionable so that the position is controlled by the pressure of the stock flowing on opposite sides of the trailing element.
  • the element is preferably free of attachment at the pondsides, but can be attached at the pondsides in some structures where movement due to hydraulic forces is small.
  • a trailing element formed of a single material may be used, a laminate may be employed such as illustrated in Figure 2 wherein different physical properties of different layers can be taken advantage of.
  • Various thicknesses of the trailing edge of the elements may be employed, but 0.254 mm (10 mils) to 3.048 mm (120 mils) is a thickness that has been found to be satisfactory.

Landscapes

  • Paper (AREA)
  • Feeding Of Articles By Means Other Than Belts Or Rollers (AREA)
  • Laminated Bodies (AREA)
EP84630167A 1983-11-25 1984-11-09 Converflo trailing element Expired EP0147350B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US55515883A 1983-11-25 1983-11-25
US555158 1983-11-25

Publications (3)

Publication Number Publication Date
EP0147350A2 EP0147350A2 (en) 1985-07-03
EP0147350A3 EP0147350A3 (en) 1986-06-25
EP0147350B1 true EP0147350B1 (en) 1989-03-15

Family

ID=24216193

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84630167A Expired EP0147350B1 (en) 1983-11-25 1984-11-09 Converflo trailing element

Country Status (15)

Country Link
EP (1) EP0147350B1 (es)
JP (1) JPS60134093A (es)
KR (1) KR860001627B1 (es)
AR (1) AR241606A1 (es)
AU (1) AU570746B2 (es)
BR (1) BR8405925A (es)
CA (1) CA1230251A (es)
DE (2) DE147350T1 (es)
ES (1) ES537930A0 (es)
FI (1) FI81145C (es)
IN (1) IN162165B (es)
MX (1) MX161597A (es)
NO (1) NO162476C (es)
PH (1) PH22238A (es)
ZA (1) ZA848555B (es)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4440079A1 (de) * 1994-11-10 1996-05-23 Voith Sulzer Papiermasch Gmbh Mehrschichten-Stoffauflauf
DE19962709A1 (de) * 1999-12-23 2001-06-28 Voith Paper Patent Gmbh Stoffauflauf
DE10051802A1 (de) * 2000-10-18 2002-04-25 Voith Paper Patent Gmbh Lamelle eines Stoffauflaufs einer Papier-, Karton- oder Tissuemaschine

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5133836A (en) * 1991-09-20 1992-07-28 Kimberly-Clark Corporation Papermaking headbox having extended divider sheet
EP0681057B1 (de) * 1994-04-29 2002-08-28 Voith Paper Patent GmbH Mehrschichten-Stoffauflauf
SE506931C2 (sv) † 1996-06-12 1998-03-02 Valmet Karlstad Ab Flerskiktsinloppslåda för en pappersmaskin
DE19715790A1 (de) * 1997-04-16 1998-10-22 Voith Sulzer Papiermasch Gmbh Vorrichtung zur Bildung einer Stoffsuspensionslage
WO1998051856A1 (en) * 1997-05-12 1998-11-19 Beloit Technologies, Inc. A trailing element device
DE10308555A1 (de) * 2003-02-27 2004-10-21 Voith Paper Patent Gmbh Stoffauflauf
JPWO2006038285A1 (ja) 2004-10-05 2008-05-29 三菱重工業株式会社 抄紙機のフローシート及びその製造方法
DE102006042811A1 (de) 2006-09-08 2008-03-27 Voith Patent Gmbh Trennelement eines Stoffauflaufs einer Maschine zur Herstellung einer Faserstoffbahn, Verfahren zu dessen Herstellung und dessen Verwendung

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA936722A (en) * 1970-08-31 1973-11-13 A. Betley Raymond Headbox slice chamber
US3939037A (en) * 1973-03-27 1976-02-17 Beloit Corporation Headbox with flexible trailing elements
US4133715A (en) * 1977-03-29 1979-01-09 Beloit Corporation Headbox and holders for floating slice chamber dividers
US4128455A (en) * 1977-05-20 1978-12-05 Beloit Corporation Headbox trailing element mounting and method
US4566945A (en) * 1984-04-11 1986-01-28 Beloit Corporation Headbox trailing element

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4440079A1 (de) * 1994-11-10 1996-05-23 Voith Sulzer Papiermasch Gmbh Mehrschichten-Stoffauflauf
DE19962709A1 (de) * 1999-12-23 2001-06-28 Voith Paper Patent Gmbh Stoffauflauf
DE10051802A1 (de) * 2000-10-18 2002-04-25 Voith Paper Patent Gmbh Lamelle eines Stoffauflaufs einer Papier-, Karton- oder Tissuemaschine

Also Published As

Publication number Publication date
BR8405925A (pt) 1985-09-10
ES8507641A1 (es) 1985-10-01
MX161597A (es) 1990-11-14
KR850003742A (ko) 1985-06-26
JPS60134093A (ja) 1985-07-17
DE147350T1 (de) 1986-08-14
ES537930A0 (es) 1985-10-01
IN162165B (es) 1988-04-09
JPS6146597B2 (es) 1986-10-15
NO162476C (no) 1990-01-03
NO844431L (no) 1985-05-28
AR241606A1 (es) 1992-09-30
ZA848555B (en) 1985-06-26
DE3477215D1 (en) 1989-04-20
EP0147350A3 (en) 1986-06-25
EP0147350A2 (en) 1985-07-03
AU570746B2 (en) 1988-03-24
FI81145B (fi) 1990-05-31
KR860001627B1 (ko) 1986-10-14
FI844059L (fi) 1985-05-26
AU3564284A (en) 1985-05-30
PH22238A (en) 1988-07-01
FI81145C (fi) 1990-09-10
CA1230251A (en) 1987-12-15
NO162476B (no) 1989-09-25
FI844059A0 (fi) 1984-10-16

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