Classifications

• • 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
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F9/00—Complete machines for making continuous webs of paper
  • D21F9/003—Complete machines for making continuous webs of paper of the twin-wire type

Definitions

• This invention relates to a forming apparatus for forming a web from stock. More particularly, the present invention relates to a forming apparatus for forming a web from stock ejected through a slice lip of a headbox into a forming section defined between a first and a second wire.
• a headbox was disposed at the upstream end of a moving fourdrinier wire and stock was ejected from the slice lip of the headbox onto the forming wire such that water drained through the wire leaving a formed web on the top surface of the wire.
• the speed of the former is considerably less than the speed of the former when forming lightweight grades because more time is required in draining the water from the larger quantity of stock used in the production of heavier grade webs.
• the slice lip be disposed as close as possible to the upstream end of the forming section. If the headbox is disposed at a relatively considerable distance from the upstream end of the forming section, there exists a tendency for the trajectory of the jet of stock to be excessively curved and the angle of impingement of the stock relative to the lower wire to be increased to an unacceptable angle.
• the impingement angle relative to the lower wire should be as small as possible so that as the jet impinges on the wire, minimum disturbance to the stock occurs and the stock impinges on the lower wire at a speed which is the same as that of the lower wire.
• the present invention attains the aforementioned objective by substituting turning bars for the breast rolls disclosed in the aforementioned proposal as taught in US Patent No. 4,830,709. Therefore, it is a primary object of the present invention to provide a high capacity forming apparatus which overcomes the aforementioned inadequacies of the prior art proposals and which provides a significant contribution to the art of forming a web from stock. •
• Another object of the present invention is the provision of a twin-wire forming apparatus including a first and a second turning bar which permit the headbox slice lip to be disposed in close proximity to the first or upstream end of the forming section defined by the wires.
• Another object of the present invention is the provision of a forming apparatus which includes at least two auto slices with means for adjusting the vacuum slots of the auto slices relative to the second wire for varying fthe amount of water removed from the second wire.
• Another object of the present invention is the provision of a forming apparatus in which the forming section is disposed substantially horizontally.
• Another object of the present invention is the provision of a forming apparatus in which the foriiing section follows a generally sinusoidal path from the first to the second end thereof.
• Another object of the present invention is the provision of a vacuum box disposed between the first and the second vacuum slots and on the opposite side of the wires relative to the vacuum slots, the vacuum box havi4g a curved surface which permits removal of water downwardly through the first wire and upward removal of water centrifugally through the second wire.
• Another object of the present invention is the provision of a forming apparatus which includes at least one further vacuum slot disposed between the first and the second vacuum slot for upward removal of water through the second wire.
• the present invention relates to a forming apparatus and method for forming a web from stock. More particularly, the present invention relates to a forming apparatus and method for forming a web from stock ejected through a slice lip of a headbox.
• the apparatus includes a first wire which extends in an endless loop past the slice lip such that the stock is ejected through the slice lip onto the first wire.
• a second wire extends in a further endless loop with the second wire cooperating with the first wire for defining therebetween a forming section having a first and a second end such that the web is formed during passage of the stock through the forming section.
• a first turning bar is disposed within the endless loop and adjacent to the first end of the forming section such that the first wire is sandwiched between the stock and the first turning bar.
• a second turning bar is disposed within the further endless loop and adjacent to the first end of the forming section such that the stock is disposed between the wires, the wires being disposed between the turning bars permitting the slice lip to be disposed in close proximity to the first end of the forming section.
• a curved drainage means is disposed within the endless loop immediately downstream relative to the first turning bar for removing a first portion of water from the stock through the first wire and for removing a second portion of water centrifugally through the second wire during passage of the stock through the forming section and past the curved draining means.
• a first vacuum slot is disposed within the further endless loop and extends in a cross-machine direction immediately downstream relative to the curved drainage means for removing a third portion of water from the stock through the second wire.
• a vacuum box is disposed within the endless loop immediately downstream relative to the vacuum slot with the vacuum box defining a curved surface for removing a fourth portion of water from the stock through the first wire.
• a second vacuum slot is disposed within the further endless loop and extends in a cross-machine direction downstream relative to the vacuum box for removing further water from the stock through the second wire.
• a further curved drainage means is disposed within the further endless loop and immediately downstream relative to the second vacuum slot"for removing water from the stock through the second wire. • Thfe curvature of the curved drainage means and the vacuum box is opposite to the curvature of the further curved drainage means such that the stock is progressively drained through both wires during passage through the forming section from the first towards the second end thereof.
• the first wire is disposed -relative
• the forming section is disposed substantially horizontally and the forming section follows a generally sinusoidal" * ath.
• the turning bars are of ceramic material and the curved drainage means also includes a plurality of drainage slots which.ate connected to a source of partial vacuum. - '. "-
• the curved drainage means defines a face having a radius of curvature which is greater than the radius of curvature of the curved surface of the vacuum box.
• the first vacuum slot is a first auto slice which includes adjusting means for adjusting the vertical and/or "the angular position of the first vacuum slot relative yto the second wire.
• the adjusting means also permits movement of the first vacuum slot between the curved drainage means and the vacuum box.
• the curved surface of the vacuum box permits centrifugal removal of a fifth portion of water from the stock through the second wire.
• the forming apparatus includes an adjustable foil which is disposed within the endless loop between the vacuum box and the second vacuum slot for assisting removal of further water through the second vacuum slot.
• the forming apparatus also includes a further vacuum slot which is disposed within the further endless loop and disposed between the first and second vacuum slots for removing water from the stock through the second wire.
• the second vacuum slot is a second auto slice which includes further adjusting means for adjusting the second vacuum slot relative to the second wire for skimming the further water removed from the stock through the second wire.
• the further curved drainage means also includes a plurality of cross-machine direction shoes defining therebetween a plurality of openings connected to a source of partial vacuum for removing water from the stock through the second wire.
• the present invention also includes a method of forming a web from stock ejected through a slice lip of a headbox.
• the method comprises the steps of moving a first wire, which extends in an endless loop, past the slice lip and then ejecting the stock through the slice lip onto the first wire.
• the arrangement is such that the stock contacts the first wire at a minimal angle of impingement due to the first wire extending around a first turning bar disposed adjacent to the point of impingement of the stock onto the first wire.
• the method includes the step of moving a second wire, which extends in a further endless loop, around a second turning bar such that the second turning bar is disposed adjacent to the first turning bar so that the slice lip is disposed in close proximity to a first end of the forming section defined between the wires.
• the method includes the step of forming the web from the stock during passage of the stock through the forming section by progressively removing water from the stock through both wires. - , _ ⁇
• the step of forming the web from stock during passage of the stock through the forming section includes removing a portion of water from.t_ e stock through a curved vacuum box disposed downstream and on the opposite side of the wires relative to a vacuum slot.
• Figure 1 is a side-elevational view of a forming' apparatus according to the present invention
• Figure 2 is an enlarged fragmentary view of the drainage means
• Figure 3 is an enlarged fragmentary view of the curved inverted vacuum box.
• Figure 4 is a side-elevational view of an alternative embodiment of the present invention showing a further vacuum slot disposed between the first and the second vacuum slots.
• FIG. 1 is a side-elevational view of a forming apparatus generally designated 10 according to a preferred embodiment of the present invention.
• the forming apparatus 10 forms a web W from stock S ejected through a slice lip 12 of a headbox generally designated 14.
• the apparatus 10 includes a first wire 16 which extends in an endless loop generally designated 18 past the slice lip 12 such that the stock S is ejected through the slice lip 12 onto the first wire 16.
• a second wire 20 extends in a further endless loop generally designated 22.
• the second wire 20 cooperates with the first wire 16 for defining therebetween a forming section generally designated 24 having a first and a second end 26 and 28, respectively, such that the web W is formed during passage of the stock S through the forming section 24.
• a first turning bar 30 is disposed within the endless loop 18 and adjacent to the first end 26 of the forming section 24 such that the first wire 16 is sandwiched between the stock S and the first turning bar 30.
• a second turning bar 32 is disposed within the further endless loop 22 and adjacent to the first end 26 of the forming section 24 such that the stock S is disposed between the wires 16 and 20.
• the wires 16 and 20 respectively are disposed between the turning bars 30 and 32 respectively thereby permitting the slice lip 12 to be disposed in close proximity to the first end 26 of the forming section 24.
• a curved drainage means generally designated 34 is disposed within the endless loop 18 immediately downstream relative to the first turning bar 30.
• the drainage means 34 removes a first portion of water from the stock S through the first wire 16 and removes a second portion,of water centrifugally through the second wire 20 during passage of the stock S through the forming section 24 and past the curved drainage means 34.
• a first vacuum slot generally designated 36 is disposed within the further endless loop 22 and extends in a cross-machine direction immediately downstream 'relative to the curved drainage means 34 for removing a third portion of water from the stock S through the second wire 20.
• a vacuum box 38 is disposed within the endless loop 18 immediately downstream relative to the vacuum slot 36.
• the vacuum box 38 defines a curved surface 40 for removing a fourth portion of water from the stock S through the first wire 16 and removes another portion of water centrifugally through the second wire 20 during passage of the stock S through the forming section.
• a second vacuum slot generally designated 42 is disposed within the further endless loop 22 and-e' ⁇ tends in a cross-machine direction downstream relative to the vacuum box 38 for removing further water from the stock S through the second wire 20.
• a further curved drainage means generally designated 44 is disposed within the further endless loop and immediately downstream relative to the second vacuum slot 42 for removing water from the stock S through the second wire 20.
• the curvature of the curved drainage means 34 and the vacuum box 38 are opposite to the curvature of the further curved drainage means 44 such that the stock S is progressively drained through both wires 16 and 20 respectively during passage through the forming section 24 from the first end 26 towards the second end 28 thereof.
• the forming apparatus 10 is arranged such that the first wire 16 is disposed relative to the slice lip 12 so that the stock S impinges on the first wire 16 before contacting the second wire 22.
• the forming section 10 is disposed substantially horizontally and the forming section 24 follows a generally sinusoidal path.
• the turning bars 30 and 32 are of ceramic material.
• Figure 2 is an enlarged fragmentary view of the drainage means 34 in which the curved drainage means 34 further includes a plurality of support foils 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62 and 63 which define therebetween a plurality of drainage slots 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80 and 81.
• the plurality of drainage slots 64 to 81 are connected to a source of partial vacuum 82.
• the curved drainage means 34 defines a face 84 having a radius of curvature which is greater than the radius of curvature of the curved surface 40 of the vacuum box 38.
• the first vacuum slot 3 ⁇ f> is a first auto slice 86 which includes adjusting means..88 for adjusting the angular and vertical position of the first vacuum slot 36 relative to the second wire 20.
• the adjusting means 88 permits movement of the first vacuum slot 36 between the curved drainage means 34 and the vacuum box 38.
• the curved surface 40 of the vacuum box 38 also permits centrifugal removal of a fifth portion of water from the stock S through the second wire 20.
• Figure 3 is an enlarged fragmentary view showing the further curved drainage means or curved inverted vacuum boxes 44.
• the forming apparatus 10 also includes an adjustable vacuum foil 90 which is disposed within the endless loop 18 between the vacuum box 38 and the second vacuum slot 42 for assisting removal of the further water through the second vacuum slot 42.
• Figure 3 also shows the second vacuum slot 42 as a second auto slice 92 with the second auto slice 92 further including further adjusting means 94 for adjusting the second vacuum slot 42 relative to the second wire 20* for skimming the further water removed from the stock S through the second wire 20.
• Figure 3 shows the further curved drainage means 44 as including a plurality of cross-machine direction shoes 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113 and 114 which define therebetween a plurality of openings 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128,' 129, 130, 131,and 132 connected to a source of partial vacuum (not shown) for removing water from the stock through the second wire 20.
• a source of partial vacuum not shown
• a forming apparatus generally-* ' designated 10A further includes a further vacuum slot 134 which is disposed within a further endless loop 18A and disposed between the first and the second vacuum slots 36A and 42A respectively for removing water from the stock through the second wire 20A.
• high consistency stock S is ejected from the headbox 14 through the slice lip 12 such that the angle of impingement of the jet of stock relative to the first wire 16 is very small. Furthermore, the slice lip 12 is able to be disposed in very close proximity to the first end 26 of the forming section 24 due to the provision of the turning bars 30 and 32 respectively. Therefore, according to the present invention, when ejecting high consistency stock at relatively low machine speeds, the stock is deposited on the lower wire 16 with minimal disturbance of the stock.
• a first portion of water is removed downwardly through the curved drainage means 34 and a second portion of water is removed upwardly through the second wire 20 due to the centrifugal force applied to the stock during passage of the stock through the forming section 24 around the curved drainage means 34.
• the vacuum box 38 having a curved surface 40 results in a fifth portion of water being removed upwardly through the second wire 20.
• the first wire 16 then passes over the foil 90 which assists the removal of a further portion of water through the second vacuum slot 42.
• the wires then proceed to extend around at least one curved inverted vacuum box or further curved drainage means 44 for removing water through the second wire 20.
• the curved drainage means 34 and vacuum box 38 have a radius of curvature which is opposite to the radius of curvature of the further curved drainage means 44 so that the forming section 24 follows a generally sinusoidal configuration from the first end 26 to the second end 28 of the forming section 24.
• the operation of the apparatus shown in figure 4 is similar to the operation of the apparatus shown in figures 1-3 except in that a further auto slice 134 is used for assisting withdrawal of water upwardly through the wire 20A.
• the aforementioned arrangement not only permits progressive drainage through both wires -during passage through the forming section but also permits the high consistency stock to be ejected into the forming section with a minimum trajectory thereby improving formation and the two-sidedness of the resultant web.

Landscapes

• Paper (AREA)
• Containers And Plastic Fillers For Packaging (AREA)
• Replacement Of Web Rolls (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10651789

Family Applications (1)

Country Status (9)

Cited By (5)

Citations (2)

Family Cites Families (1)

• 1989
  • 1989-02-16 GB GB898903517A patent/GB8903517D0/en active Pending
• 1990
  • 1990-01-17 WO PCT/US1990/000213 patent/WO1990009481A1/en active IP Right Grant
  • 1990-01-17 EP EP90902035A patent/EP0458799B1/en not_active Expired - Lifetime
  • 1990-01-17 CA CA002046588A patent/CA2046588C/en not_active Expired - Lifetime
  • 1990-01-17 JP JP2502150A patent/JPH0726354B2/ja not_active Expired - Lifetime
  • 1990-01-17 AU AU49439/90A patent/AU629901B2/en not_active Ceased
  • 1990-01-17 BR BR909007120A patent/BR9007120A/pt not_active Application Discontinuation
  • 1990-01-17 KR KR1019910700900A patent/KR0153748B1/ko not_active IP Right Cessation
• 1991
  • 1991-08-15 FI FI913867A patent/FI913867A0/fi unknown

Patent Citations (2)

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