Abstract: A headbox apparatus for a papermaking machine is disclosed. The headbox apparatus defines a flow path for stock flowing between an upstream header and a downstream slice lip. Each block and an adjacent block of a plurality of blocks defines therebetween a flow tube for the flow therethrough of the stock. An upstream ramp is defined by a first surface for generating an upstream vortex adjacent to the first surface. A downstream ramp is defined by a second surface for generating a downstream vortex adjacent to the second surface. Adjacent blocks also generate downstream vortices which rotate in opposite directions relative to each other within the flow tube so that impact of the upstream and downstream vortices on a flow consistency and a velocity uniformity of the stock is reduced.

Abstract: A tube bank apparatus is disclosed for distributing stock in a headbox of a papermaking machine. The apparatus includes a tube having a first and a second portion for the flow therethrough of the stock. The first portion defines a bore for the flow therethrough of the stock, the bore having an upstream and a downstream end. The second portion defines a passage for the flow therethrough of the stock, the passage having an upstream and a downstream extremity. The upstream extremity of the passage cooperates with the downstream end of the bore so that the stock flows from the upstream end to the downstream end of the bore and then through the upstream extremity and then the downstream extremity of the passage.

Abstract: A headbox apparatus for a papermaking machine is disclosed. The headbox apparatus defines a flow path for stock flowing between an upstream header and a downstream slice lip. Each block and an adjacent block of a plurality of blocks defines therebetween a flow tube for the flow therethrough of the stock. An upstream ramp is defined by a first surface for generating an upstream vortex adjacent to the first surface. A downstream ramp is defined by a second surface for generating a downstream vortex adjacent to the second surface. Adjacent blocks also generate downstream vortices which rotate in opposite directions relative to each other within the flow tube so that impact of the upstream and downstream vortices on a flow consistency and a velocity uniformity of the stock is reduced.

Abstract: Embodiments for methods and apparatuses for forming a nonwoven web are described herein. In one embodiment, an apparatus includes one or more sources configured to dispense a first fluid flow stream comprising a fiber and a second fluid flow stream also comprising a fiber. The apparatus also includes a mixing partition downstream from the one or more sources, where the mixing partition is positioned between the first and second flow streams from the one or more sources. The mixing partition defines one or more openings that permit fluid communication between the two flow streams. The apparatus also includes a receiving region situated downstream from the one or more sources and designed to receive at least a combined flow stream and form a nonwoven web by collecting fiber from the combined flow stream.

Abstract: A headbox for a machine for producing a fibrous material web, in particular a paper or cardboard web, includes: a central assembly preferably forming the carrier elements of a turbulence generator, said assembly having a table leaf on the bottom side; and a headbox nozzle adjoining directly downstream in the machine running direction and extending in the machine transverse direction, said nozzle comprising at least one lower and one upper continuous nozzle wall extending over the machine width. The lower nozzle wall of the headbox nozzle of the headbox includes a lower lip plate, in particular a lower lip carrier plate, which is connected, in particular welded, to the table leaf of the central assembly by means of ribs extending in the machine running direction and spaced apart in the machine transverse direction. The ribs are designed in an elastic or pliable manner in the machine transverse direction.

Abstract: A sheet-forming system includes a separating wedge with a separating wedge protrusion in a range of 0.05 to 3.0 of the largest single gap width of at least two nozzle chambers. The separating wedge includes two separating wedge areas, each having one separating wedge angle, an upstream separating wedge starting area and a downstream separating wedge ending area. The two separating wedge angles assume different angles. The separating wedge starting angle of the upstream separating wedge initial area assumes a greater angle than the separating wedge ending angle of the downstream separating wedge end area. At least one separating wedge surface is a nonplanar transitional area between the two separating wedge areas. The fibrous material suspension free jet formed from at least two fibrous material suspension streams has a free jet length of 100 to 500 mm. The forming roll has a diameter of 1,200 to 2,500 mm.

Abstract: Embodiments for methods and apparatuses for forming a nonwoven web are described herein. In one embodiment, an apparatus includes one or more sources configured to dispense a first fluid flow stream comprising a fiber and a second fluid flow stream also comprising a fiber. The apparatus also includes a mixing partition downstream from the one or more sources, where the mixing partition is positioned between the first and second flow streams from the one or more sources. The mixing partition defines one or more openings that permit fluid communication between the two flow streams. The apparatus also includes a receiving region situated downstream from the one or more sources and designed to receive at least a combined flow stream and form a nonwoven web by collecting fiber from the combined flow stream.

Abstract: Headbox for a machine to produce a fiber web, in particular a paper, cardboard or tissue web from at least one fibrous suspension, having a headbox nozzle comprising an upper nozzle wall and a lower nozzle wall, as well as two side walls tapering to form an outlet, and having an inner chamber through which the fibrous suspension flows in flow direction during operation of headbox, whereby on upper nozzle wall of headbox nozzle a baffle is arranged on the outlet side which is movable by way of several elements and which extends across machine width, and which has a baffle protrusion and a baffle immersion depth and which has at least two surfaces—an upstream ramp surface and a subsequent main surface contacted by a fibrous suspension during operation of headbox. The inventive headbox is characterized in that between ramp surface of baffle and main surface of baffle at least one refraction surface which is in contact during operation of headbox with a fibrous suspension is provided on baffle.

Abstract: [Problem] It provides a sheet forming machine which can make the thickness in the width direction of a sheet forming body be uniform, and also can obtain a sheet forming body which is integrated in stripe shapes by using different raw materials or raw materials of different colors in the width direction of one sheet forming body.

Abstract: The invention relates to a method in the wet end of a web forming process. In the method, at least one electrode pair (102, 103) is placed in the wet end. The electrode pair (102, 103) is supplied with a current/voltage from a power source (100), so that an electric field is set up between the electrode pair (102, 103), causing the material particles in the pulp suspension in the wet end to be electrically charged in a desired manner and to move in a desired manner in the pulp suspension in the wet end. The current/voltage of the power source (100) is controlled by means of a measuring and control unit (101) so as to cause the material particles in the pulp suspension to be electrically charged and to move in a desired manner, thus allowing the retention, formation and orientation of the material particles in the pulp suspension to be substantially improved.

Abstract: The invention relates to a sheet-forming system for a machine for producing a multilayer fibrous material web, comprising a multilayer headbox having a headbox nozzle, which has at least two nozzle chambers that are separated from one another by at least one separating wedge, and further comprising a gap former, which is connected directly downstream of the multilayer headbox and has two continuous revolving screens, the first screen of which runs over a circumferential area of a forming roll and the second screen of which runs over a circumferential area of a breast roll and then runs onto the first screen in the area of the forming roll to form a wedge-shaped material inlet gap. The sheet-forming system according to the invention is characterized in that the separating wedge has a separating wedge protrusion in a range of 0.05 to 3.

Abstract: Method and device for producing a web of tissue. In the method, the web of tissue is led over at least one drying cylinder, doctored off the latter with a creping doctor and then wound up by way of a winding device. The web of tissue is supported at least largely over the entire distance between creping doctor and winding device on one side by a transfer device, so that there is only a short free web draw, while its other side is free. The device includes at least one drying cylinder, a creping doctor arranged on the drying cylinder and a winding device that winds up the web of tissue. Between the creping doctor and the winding device, a transfer device at least largely bridges the entire distance which supports the web of tissue on one side. There is a short free web draw, but its other side is left free.

Abstract: The invention relates to a dual-layer material ramp for a machine for producing a dual-layered fibrous web, in particular a dual-layered paper or cardboard web, from two fibrous suspensions, comprising a material ramp nozzle with two nozzle spaces extending along the width and separated from one another on the inside by a separating wedge, said nozzle spaces guiding a respective fibrous suspension during operation of the dual-layer material ramp as fibrous suspension streams and coming together, each of said nozzle spaces comprising an upstream feed device, a downstream outlet gap with a gap width, said gap extending along the width and an outer wall on the outside, wherein the separating wedge comprises two separating wedge surfaces that are contacted by the respective fibrous suspension stream during operation of the dual-layer material ramp.

Abstract: A tube bank apparatus is disclosed for distributing stock in a headbox of a papermaking machine. The apparatus includes a tube having a first and a second portion for the flow therethrough of the stock. The first portion defines a bore for the flow therethrough of the stock, the bore having an upstream and a downstream end. The second portion defines a passage for the flow therethrough of the stock, the passage having an upstream and a downstream extremity. The upstream extremity of the passage cooperates with the downstream end of the bore so that the stock flows from the upstream end to the downstream end of the bore and then through the upstream extremity and then the downstream extremity of the passage. The downstream end of the bore has a cross-sectional area which is less than a further cross-sectional area of the upstream extremity of the passage. Also, the downstream extremity of the passage has a cross-section of trapezoidal configuration.

Abstract: A headbox apparatus for a papermaking machine is disclosed. The headbox apparatus defines a flow path for stock flowing between an upstream location and a downstream slice lip. The apparatus includes a plurality of blocks which are anchored within the flow path between the upstream location and the slice lip. Each block and an adjacent block of the plurality of blocks define therebetween a flow tube for the flow therethrough of the stock. The flow tube has an upstream portion having an upstream and a downstream end. The flow tube has a downstream portion having an upstream and a downstream extremity, the upstream extremity of the downstream portion extending from the downstream end of the upstream portion. The downstream portion of the flow tube has a volume which is greater than a further volume of the upstream portion of the flow tube such that when the stock flows from the upstream portion to the downstream portion of the flow tube, the stock is mixed within the downstream portion.

Abstract: A headbox apparatus is disclosed for a papermaking machine. The headbox apparatus defines a flow path for stock flowing between an upstream header and a downstream slice lip. The apparatus includes a plurality of elements which are anchored within the flow path between the header and the slice lip. Each element and an adjacent element of the plurality of elements defines therebetween a flow tube for the flow therethrough of the stock. The flow tube has an upstream portion and a downstream portion that gradually widens in a direction from the header to the slice lip.

Abstract: A procedure and arrangement to control the lamella of a headbox's lip channel, when the mass flow goes in the headbox (3) through the lip channel (2), in which case single mass flows are held separate from each other with the lamella (1) before the flows are united after the lamella. The lamella's dimensions, mechanical characteristics and/or dynamic characteristics are changed at least in the lamella's border area with an active structure, which is active and/or passive active tool and/or active and/or passive active material.

Abstract: To smooth the surface of a flow sheet that is used in a paper machine and make the flow sheet easy to handle, reinforced fibers are disposed in a mold 5. The entire mold 5 is covered with enclosing members 10, 11 so that an enclosed space 12 is formed inside the enclosing members 10, 11. While air in the enclosed space 12 is being suctioned through one end of the enclosed space 12, matrix resin is supplied to the reinforced fibers through the other end of the enclosed space 12 to impregnate the reinforced fibers with the matrix resin, and the matrix resin is hardened, whereby there is obtained a flow sheet whose surface smoothness is 0.25 ?m or less in terms of arithmetical mean roughness.

Abstract: A tube bank apparatus is disclosed for distributing stock in a headbox of a papermaking machine. The apparatus includes a tube having a first and a second portion for the flow therethrough of the stock. The first portion defines a bore for the flow therethrough of the stock, the bore having an upstream and a downstream end. The second portion defines a passage for the flow therethrough of the stock, the passage having an upstream and a downstream extremity. The upstream extremity of the passage cooperates with the downstream end of the bore so that the stock flows from the upstream end to the downstream end of the bore and then through the upstream extremity and then the downstream extremity of the passage.

Abstract: A tube bank apparatus is disclosed for distributing stock in a headbox of a papermaking machine. The apparatus includes a tube having a first and a second portion for the flow therethrough of the stock. The first portion defines a bore for the flow therethrough of the stock, the bore having an upstream and a downstream end. The second portion defines a passage for the flow therethrough of the stock, the passage having an upstream and a downstream extremity. The upstream extremity of the passage cooperates with the downstream end of the bore so that the stock flows from the upstream end to the downstream end of the bore and then through the upstream extremity and then the downstream extremity of the passage. The downstream end of the bore has a cross-sectional area which is less than a further cross-sectional area of the upstream extremity of the passage. Also, the downstream extremity of the passage has a cross-section of trapezoidal configuration.

Abstract: A headbox including a stock dilution profiling arrangement and associated stock delivery systems are provided, which together deliver to the forming section of a papermaking machine a uniform stock flow with more consistent basis weight and fiber orientation profiles than has previously been possible. These improvements in basis weight uniformity and fiber orientation profile provide benefits in paper sheet formation and related paper properties.

Abstract: A vane intended for a headbox of a paper machine or equivalent is moistened and enclosed in a vapor-proof package to ensure the straightness of the vane. At least a portion of the vane is made of a water-absorbing material, such as plastic or a composite. Advantageously, the vane contains moisture in an amount that corresponds to the equilibrium moisture content of the vane in headbox conditions. It is enclosed in a package, preferably a vacuum package, which retains the moisture of the vane until the vane is put into use.

Abstract: An arrangement in the headbox of a paper or cardboard machine has a pulp suspension feed system distributing the suspension over the width of the headbox. At least one first flow resistance element, such as an aperture plate and/or tube system, is provided with flow apertures, from which headbox the pulp suspension is passed via at least one chamber, such as an equalizing chamber and/or the slice gap of a slice chamber, onto a forming wire or equivalent. The arrangement comprises at least one pulp flow guide plate, preferably arranged mainly in the transverse direction of the headbox, having at least one groove formed in its guide surface.

Abstract: A headbox apparatus of a paper machine or equivalent has a body (11). Dilution water (arrow L2) is conducted through at least two rows of ducts (12a1, 12a2 . . . ) into each body mixing chambers (13a1, 13a2 . . . ). Each mixing chamber (13a1, 13a2 . . . ) is limited by vertical walls (T1), a bottom wall (T2) and a covering wall (T3), and a partition wall (16a1, 16a2 . . . ). The ducts (14a1.1, 14a1.2 . . . ) on the inlet side of the mixing chamber extend into the mixing chamber (13a1, 13a2 . . . ) at a distance (h1) from the ducts (15a1.1, 15a1.2 . . . , 15a2.2 . . . ) on the outlet side of the mixing chamber (13a1, 13a2 . . . ), whereby an annular gap (D1) is left between the aligned duct (14a1.1, 14a1.2 . . . 14a2.1, 14a2.2 . . . ) on the inlet side and the duct (15a1.1, 15a1.2 . . . , 15a2.1, 15a2.2 . . . ) on the outlet side. Each mixing chamber (13a1, 13a2 . . . ) is filled by dilution water which is conducted through the annular gap (D1) to join the stock (m1).

Abstract: The device for joining at least two plies of paper (V1, V2), in particular tissue paper, comprises a ply-bonding unit (9) and moistening means (11) to moisten at least one of said two plies before joining.

Abstract: In a method of forming a layered fibrous web, the method includes the steps of leading at least two different fiber suspensions through a head box (10), separating the fiber suspensions from each other by a blade device (18, 180), supplying the fiber suspensions to a web forming device (24) and forming a water layer having a transversely uniform flow at an outlet at the end of the blade device (18, 180), such that the water layer constitutes an extension of the blade device and thereby prevents mixing of the fiber suspensions. The blade device (18, 180) can be freely movable in a substantially vertical direction in order to permit an equalization of pressure between the fiber suspension layers separated by the blade device and thereby reducing wake effects downstream the edge of the blade device. A paper machine for carrying out the method is also disclosed.

Abstract: The present invention relates to a method and apparatus for foam forming, wherein fibrous foam suspension is introduced from the head box (78, 178) of a production machine to the web forming section thereof. At least one solid material is mixed into the foam in the head box (78, 178). The method and the apparatus of the invention are particularly suitable for manufacturing various web-like products of cellulose, glass fiber, aramide, sisal, or other corresponding fibre material.

Abstract: A headbox apparatus for a papermaking machine is disclosed. The headbox apparatus defines a flow path for stock flowing between an upstream location and a downstream slice lip. The apparatus includes a plurality of blocks which are anchored within the flow path between the upstream location and the slice lip. Each block and an adjacent block of the plurality of blocks define therebetween a flow tube for the flow therethrough of the stock. The flow tube has an upstream portion having an upstream and a downstream end. The flow tube has a downstream portion having an upstream and a downstream extremity, the upstream extremity of the downstream portion extending from the downstream end of the upstream portion. The downstream portion of the flow tube has a volume which is greater than a further volume of the upstream portion of the flow tube such that when the stock flows from the upstream portion to the downstream portion of the flow tube, the stock is mixed within the downstream portion.

Abstract: Virgin stock is conducted to a paper or board machine and further to a centrifugal cleaner installation (12) into its first centrifugal cleaner step (12a1). From the first centrifugal cleaner step (12a1) the accept is conducted into a multi-layer headbox (10) to form a layer of the web determined according to the concerned fraction. From a second step (12a2) and/or from lower steps (12a3, 12a4 . . . ) of the centrifugal cleaner installation (12) a second fraction or more fractions are conducted into the multi-layer headbox (10) to form a second layer or other layers of the web, which are determined according to the pulp fractionation taking place in the concerned second step or lower steps.

Abstract: A procedure and arrangement to control the lamella of a headbox's lip channel, when the mass flow goes in the headbox (3) through the lip channel (2), in which case single mass flows are held separate from each other with the lamella (1) before the flows are united after the lamella. The lamella's dimensions, mechanical characteristics and/or dynamic characteristics are changed at least in the lamella's border area with an active structure, which is active and/or passive active tool and/or active and/or passive active material.

Abstract: A method of ensuring the flatness of a vane that is mounted in a headbox by means of a mounting arrangement including engagement dowels for cooperation with a downstream support wall of a transverse groove, said vane being affected during operation by shearing forces from the stock and by retaining forces from the mounting arrangement. In accordance with the invention outer engagement dowels are mounted at the side edges of the vane to cooperate during a specific period of time, as the only engagement dowels with the downstream support wall in order to take up said shearing forces, whereby tensile stresses will arise in the downstream end portion of the vane in the cross machine direction.

Abstract: A headbox (10) of a paper machine or such includes a bypass manifold (J1), from which the pulp is conducted by way of pipes (11a1.1, 11a1.2 . . . 11a2.1, 11a2.2 . . . ) of pipe rows in a set of pipes (11) and an intermediate chamber (E) into a turbulence generator (12), or from the bypass manifold (J1) directly into the turbulence generator and by way of the pipes (12a1.1, 12a1.2, . . . ; 12a2.1, 12a2.2 . . . ) of the turbulence generator's (12) pipe rows into a lip cone (K) and further out from the headbox on to a formation wire. The turbulence generator (12) of the headbox includes a fluidization element (14), wherein fluidization is carried out in one stage only and in which structure as little disturbance as possible is then caused to the fluidised flow.

Abstract: An inlet chamber is connected to a nozzle section by way of a plurality of tubes. Diluting liquid for mixing with paper stock flowing through one or each of said tubes is fed into the tube via annular inlet means. To ensure thorough mixing, channel means leading into the annular inlet means is configured to create turbulent flow of diluting liquid prior to its introduction into the tube, for example, by consisting of a helical or spiral duct, or by being provided internally with baffle means.

Abstract: A headbox, for example, in a pulp or board machine, is suitable for high basis weights which are over 400 g/m2 and for high fiber suspension consistencies which are in a range of 2–5%. The headbox has a turbulence part (1), into which a fiber suspension flows from a tube bank (2), and a slice part (3) which is situated after the turbulence part and from which the fiber suspension flows to a forming section of a fibrous web. The turbulence part (1) of the headbox has at least two passages (5, 6), which converge in the flow direction of the fiber suspension towards the slice part (3). In that connection, the fiber suspension flow is first fluidized in a tortuous turbulence passage part (11) and, after that, it decelerates in another widening deceleration passage (12).

Abstract: Multi-layer headbox for a paper machine that includes a plurality of nozzle chambers having outlet gaps located at nozzle chamber ends. Each of the plurality of nozzle chambers are assigned to different layers, and at least one of the plurality of nozzle chambers has a length in a flow direction that is different from a length of at least one other of the plurality of nozzle chambers. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

Abstract: The invention provides tube bank structure and a method of manufacturing a flow tube, which can improve the stabilization of the flow of stock in the tube bank of the headbox of a papermaking machine and prevent the development of turbulence and uneven concentration of stock flow by a simple and inexpensive means, resulting in speedup of papermaking process. Said flow tubes has a smaller diameter pipe portion of a circular cross-section in the inlet side, a larger diameter pipe portion connected to said smaller diameter pipe portion, a tapered pipe portion, and a rectangular pipe portion, the cross-sectional configuration of said tapered pipe portion being changed smoothly from circular to rectangular configuration.

Abstract: A method for fluidisation of a pulp flow in the headbox of a paper machine or such. The characteristics of the pulp flow are affected in the headbox's fluidiser (14) in one step only, whereby the height (h1) of the step is at least equal to the average fibre length, and after the fluidiser (14) the biggest permissible step expression in the flow channel in direction z is smaller than the average fibre length.

Abstract: A method of ensuring the flatness of a vane that is mounted in a headbox by means of a mounting arrangement including engagement dowels for cooperation with a downstream support wall of a transverse groove, said vane being affected during operation by shearing forces from the stock and by retaining forces from the mounting arrangement. In accordance with the invention outer engagement dowels are mounted at the side edges of the vane to cooperate during a specific period of time, as the only engagement dowels with the downstream support wall in order to take up said shearing forces, whereby tensile stresses will arise in the downstream end portion of the vane in the cross machine direction.

Abstract: In the short circulation of a paper machine, a chemicals flow (F1) is fed into a fibre suspension flow in connection with a pipe expansion comprising a first pipe (1) and a second pipe (2) having a larger diameter than the first pipe, which pipes are connected to each other by means of an expansion step (3) perpendicular to the direction of flow. The chemicals flow (F1) can be passed so as to be mixed with the fibre suspension flow either in the second pipe (2) in an ideal mixing zone situated after the expansion step (3) or in the first pipe (1) so close to the expansion step (3) that the chemicals which are added have no time to react with the fibre suspension before the flow enters the expansion step (3).

Abstract: Apparatus and process for controlling the basis weight cross-profile, the formation, the fiber direction and other quality parameters of a pulp sheet after the headbox in a dewatering plant. The apparatus including at least one suspension feed, at least one distribution device and at least one drainage device for excess suspension from the distribution device, where the distribution device has a distribution chamber and a turbulence-generating chamber made up of a number of pipes adjacent to one another. It is mainly characterized by the two peripheral zones of the headbox, comprising distribution chamber and turbulence-generating chamber, each having a discharge device in the sheet running direction for a partial suspension stream.

Abstract: A pulp former's sealing blades extend between the headbox slice and twin forming wires and are bonded and/or pinned to blade supports which mount the blades to the slice. The blade supports have flat mounting surfaces which extend in the machine and cross machine directions and which overlie or underlie the blades supports. The blades may be affixed to the supports with an adhesive film. The supports are in turn mounted to the upper and lower sides of a pulp former headbox slice. After the adhesive bond is formed, holes are drilled through the flexible blades and into the blade supports. The holes are filled with pins which are mounted flush to the pulp side surfaces of the flexible blades. The holes through the flexible blades may be tapered, and the corresponding tapered portions of the pins may be used to clamp the flexible blades to the blade supports.

Abstract: The invention relates to a headbox of a paper machine or equivalent. The headbox comprises in its connection cleaning tubes (11a1, 11a2 . . . ), by means of which stock is separated into accept and reject, the accept being passed forward in the headbox and further onto a forming wire (H1).

Abstract: A paper/board machine headbox (10) has a stock inlet header (J), a tube bank (11), a turbulence generator (13) and a slice opening (14) which is provided with a profile bar. The headbox (10) is provided with cross direction measuring sensors (D1, D2; Dmn), by means of which the flow rate profile of the headbox (10) is determined, and the profile bar of the slice opening (14) of the headbox (10) is adjusted in the cross direction on the basis of the thus determined flow rate profile. The headbox (10) is provided with measuring sensors (D1, D2; Dmn) for determining the cross direction flow rate profile of the headbox (10) and with means for adjusting the profile bar on the basis of the flow rate profile.

Abstract: Lamella and headbox of a web production machine. The lamella is formed of at least one high-performance polymer. The at least one high-performance polymer includes high stability, high heat resistance, and good to very good resistance to at least one of alkaline solution and acid. The headbox includes the lamella.

Abstract: A vane is mounted to a turbulence generator in a headbox by a mounting arrangement that includes an assembly bar that is rigidly connected to an anchoring element of the turbulence generator. The anchoring element has an engagement groove of dovetail shape that receives a similarly shaped protrusion on the assembly bar to rigidly mount the assembly bar to the anchoring element. The assembly bar also includes a continuous journaling groove configured to receive a pivot member of the vane to fix the vane to the assembly bar while leaving the vane free to pivot about a pivot axis that extends in the cross-machine direction.

Abstract: The invention concerns a method and equipment for pulp fractionation in a paper or board machine. In the method, virgin stock is conducted to the paper or board machine and further to a centrifugal cleaner installation (12) into its first centrifugal cleaner step (12a1). From the first centrifugal cleaner step (12a1) the accept is conducted into a multi-layer headbox (10) to form a layer of the web determined according to the concerned fraction. From a second step (12a2) and/or from lower steps (12a3, 12a4 . . . 12an) of the centrifugal cleaner installation (12) a second fraction or more fractions are conducted into the multi-layer headbox (10) to form a second layer or other layers of the web, which are determined according to the pulp fractionation taking place in the concerned second step or lower steps.

Abstract: In a paper machine headbox, a stock suspension flow passes through turbulence pipes (14an) and is distributed into superimposed layers. Stepped expansion spots (16) of the flow cross-section area of the turbulence pipes (14) or the positions of trailing elements starting from between the pipe rows (Rn) and extending to the slice duct (12) of the headbox control the onset and level of turbulence in each layer. Turbulence is generated in different phases of the flow in different layers by arranging the expansion spots (16) and/or the trailing elements in superimposed layers to be located at different distances from the slice opening (13) of the headbox, whereby a different turbulence prevails at the slice opening (13) in different layers of the stock suspension flow.

Abstract: Multi-layer headbox for a paper machine that includes a plurality of nozzle chambers having outlet gaps located at nozzle chamber ends. Each of the plurality of nozzle chambers are assigned to different layers, and at least one of the plurality of nozzle chambers has a length in a flow direction that is different from a length of at least one other of the plurality of nozzle chambers. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

Abstract: The invention provides tube bank structure and a method of manufacturing a flow tube, which can improve the stabilization of the flow of stock in the tube bank of the headbox of a papermaking machine and prevent the development of turbulence and uneven concentration of stock flow by a simple and inexpensive means, resulting in speedup of papermaking process. Said flow tubes has a smaller diameter pipe portion of a circular cross-section in the inlet side, a larger diameter pipe portion connected to said smaller diameter pipe portion, a tapered pipe portion, and a rectangular pipe portion, the cross-sectional configuration of said tapered pipe portion being changed smoothly from circular to rectangular configuration.

Abstract: A headbox, for example, in a pulp or board machine, is suitable for high basis weights which are over 400 g/m2 and for high fibre suspension consistencies which are in a range of 2-5%. The headbox has a turbulence part (1), into which a fibre suspension flows from a tube bank (2), and a slice part (3) which is situated after the turbulence part and from which the fibre suspension flows to a forming section of a fibrous web. The turbulence part (1) of the headbox has at least two passages (5, 6), which converge in the flow direction of the fibre suspension towards the slice part (3). In that connection, the fibre suspension flow is first fluidized in a tortuous turbulence passage part (11) and, after that, it decelerates in another widening deceleration passage (12).