Abstract: Apparatus and method for coating a moving paper web, in which the web (2) to be coated is first guided to a coating station (7) correctly aligned and a first side of the web (2) is coated with a coat layer. Next, the web (2) is guided upwards from the coating station (7) and the first coat layer is dried using non-contact dryers (8, 9). From the dryers the web (2) is guided to the next coating station (14) correctly aligned, and the second side of the web (2) is coated with a coat layer, the web (2) is guided upwards from the coating station (14) and the coat layer on the second side of the web (2) is dried using non-contact dryers (8, 9). When the web is directed from the coating station (7) through the dryers (8, 9), it (2) is guided non-contactingly by means of air jets such that the web (2) is first non-contactingly turned in the machine direction during drying and next, similarly during drying, towards the level of the coating stations (7, 14).

Abstract: In a headbox for a paper machine a hydraulic headbox is combined with an apertured roller headbox, with at least one movable insert part (15) through which the material suspension (5) can flow being provided in the region of the flow channel (4) and/or of the nozzle channel (18) and with the flow channel (4) having a cross section through which flow takes place which broadens over at least a substantial part of its length in the direction of flow up to the moveable insert part (15).

Abstract: A turbulence generator (20) in the headbox of a paper making machine which produces internal microturbulence in the pulp suspension flow (F), whereby the homogeneity of the flow is improved. The turbulence generator (20) comprises a system of turbulence tubes, which consists of a number of turbulence tubes (22) placed one above the other and side by side. These tubes start at the inlet side of the turbulence generator (20) having thereat a substantially circular cross-section, being gradually and smoothly, in the flow direction, converted to a rectangular cell structure with planar sides. The cell structure (30) at the outlet side (23) of the turbulence generator (20) consists of an overlapping cell system, wherein there are at least two inclined middle cell rows (31, 32; 31a, 31b, 32a, 32b) placed one above the other, in which cell rows the cells have rectangular cross-sections. The cells have a shorter planar side (X) and a longer planar side (Y).

Abstract: The invention relates to a headbox of a paper or board making machine, particularly a hydraulic headbox, which has an inlet header section (1) with a manifold tube section (2) and an equalizing chamber (3) in the stock suspension flow route, a turbulence generator section (4) following the equalizing chamber (3), after which a tapered slice section (8) is located, through which the stock suspension is discharged onto the wire. The headbox also has an attenuation chamber (6) for pressure variations, which defines one or several air spaces (7) under the flow channel of the stock suspension, the spaces being connected with the flow channel by way of a connecting channel (5). The air space or spaces (7) are preferably confined by subjacent frame structures including a bottom wall (16) and vertical walls (18) and walls (19) defining the flow channel from below.

Abstract: In a headbox system for a papermaking machine with an adjustable distribution of the fiber stock suspension or pulp over the web width, the flow in the delivery slice is controlled in such a way that, across the web width, also the distribution of the fibers in respect of fiber orientation and quantity has a desired profile. For this purpose, the flow of the fiber stock suspension is controlled such that in the event of a change in the distribution of the fiber stock suspension across the web width, the horizontal component of the flow direction in the delivery slice remains, at all locations, always in the predetermined machine direction and thus transverse flows are avoided and the flow rate in the delivery slice has a predeterminate profile.

Abstract: The head box for a paper making machine joins the main distribution channel with an outlet nozzle that extends over the width of the machine. The head box has a plurality of linear, tubular flow channels extending from the distribution channel to the outlet nozzle. Just before entry into the outlet nozzle, each channel widens continuously, forming a continuous diffuser communicating into the outlet nozzle. In each tubular flow channel, a respective channel piece of reduced inside diameter is provided at or just upstream of the continuous diffuser. The entrance into the channel piece is developed as a step-like reduction in cross-section of the tubular channel, as compared with the cross-section of the tubular channel just upstream.

Abstract: Method and apparatus in the headbox of a paper machine and in its approach pipe system. In the headbox, pulp suspension is fed through the approach pipe system and a pressure screen arrangement, if any, to a distributing header part, from which the pulp suspension flow is conducted through a turbulence generator section and further to a lip section. A pulp suspension jet is discharged from a lip aperture of the lip section onto a forming wire or into a throat defined by a pair of forming wires. At least part of the approach pipe system, the distribution header part, and the turbulence generator section are arranged to have two or several substantially parallel pulp suspension flow passages. The different passages operate substantially simultaneously in parallel, when the headbox has been set to operate in a higher flow rate range.

Abstract: A headbox for a paper machine includes a distributor beam part communicating with a distribution part and a turbulence part followed by a slice part. The turbulence part is constituted by a turbulence generator member in which a plurality of flow bores are formed, the outlet mouths of the flow bores opening into flow slots formed in the turbulence generator and wherein a central plane of each flow slot forms an angle with the axes of the flow bores, the magnitude of the angle being in the range of about 5.degree. to 45.degree.. The headbox may also include an equalizing chamber in which a pulp suspension is adapted to flow in an upwardly slanted flow direction and in this case the axes of the flow bores form a declining angle with the flow direction in the equalizing chamber, which declining angle is in the range of about 5.degree. to 15.degree..

Abstract: A method and apparatus for feeding a fibre suspension onto the wire of a web former through a guiding device consisting of a plurality of guiding channels through which the fibre suspension flows parallelly and which are connected to a slice chamber leading to a slice and extending across the wire of the web former. A means for separating the dilute outer part of the jet of stock flowing in from every single flow channel is disposed downstream of the guiding device. The outer portion is deflected from the direction of flow of the thicker and more homogeneous core part and the latter is allowed to proceed up to the lip substantially maintaining its direction. Thus, a situation is reached, whereby considerably less local consistency variations occur in the lip flow across the head box. Preferably, this means is formed by a plate in which there are openings disposed coaxially with regard to the manifold tubes so that the diameter of the openings of the plate is smaller than that of the openings of the tubes.

Abstract: A system for damping the pressure fluctuations in a paper machine headbox. The headbox applying the damping system comprises an equalizing chamber communicating with an air space, this equalizing chamber having an outlet/outlets for a channel/channels leading to the equalizing chamber as well as an inlet/inlets for a channel/channels leaving the equalizing chamber. The outlet chamber is disposed with regard to the inlet channel so, and the cross surfaces of the outlet and inlet channels have been dimensioned so that the jet of stock flowing out of the outlet and expanding divergently falls substantially inside the boundaries of the inlet.

Abstract: A headbox of a paper machine has a stock distribution header part, a distribution pipe assembly connected to the stock distribution header part, an equalizing passage following the distribution pipe assembly in the flow path of the stock suspension, an air tank in immediate communication with the equalizing passage and a converging slice part following the equalizing passage, the converging slice part having a lower lip wall and an adjustable upper lip wall. A turbulence section between the equalizing passage and the converging slice part has at least one exchangeable grating cassette consisting of at least two grating plates in abutment with each other. A first of the grating plates and in the direction of the stock flow and has a plurality of apertures formed therethrough.

Abstract: A paper machine has an equalizing part between a distribution pipe system part and a turbulence section in the flow path of the pulp stock. The equalizing part has an equalizing chamber with a length in the direction of flow of the pulp stock and a front wall. An adjusting device is coupled to the front wall of the equalizing chamber for adjusting the length of the equalizing chamber by adjustment of the position of the front wall.

Abstract: Apparatus for attenuating low frequency pressure variations in a stock suspension being fed to a paper machine. The apparatus includes a pressurized overflow chamber having an inlet which delivers a stock suspension therein and an outlet for discharging stock from the chamber. A first control means controls the pressure applied to the suspension in the overflow chamber. The chamber communicates with a sump which receives the overflow from the overflow chamber. A sensing means senses the stock pressure in the inlet conduit and a second sensing means senses the level of stock in the sump. A high pass filter receives a signal from the first sensing means and a low pass filter receives a signal from the second sensing means. A summing amplifier receives the output of the high and low pass filters. A control means receives the output of the summing amplifier and is connected to the overflow means to control operation of an overflow valve in response to the output of the summing amplifier.

Abstract: Quick connect apparatus for headbox components in a paper making machine, e.g., apparatus to quickly connect and disconnect the equalizing chamber portion of the air cushion damper from associated distribution header and turbulence sections of the machine, include an elongate locking rod extending over a substantial portion of the end region of the components to be attached, the locking rod being mounted for longitudinal movement. The locking rod is provided with spaced locking portions adapted to lockingly engage correspondingly spaced portions of adjacent components to which said component is to be attached. The components are quickly connected in one embodiment by the longitudinal movement of the elongate locking rod or, in another embodiment, by the rotational movement thereof, whereby the locking portions on the rod are moved into and out of locking engagement with the corresponding spaced locking portions of the other component.

Abstract: A two-wire papermaking system for the formation of paper from paper slurry includes a first section where the slurry is maintained under pressure in a condition of minimum pond height under the guidance of a looped lower (bottom) web carrying wire having a single run over a progressive series of independently controlled dewatering boxes immediately prior to passage from the headbox through the adjacent slice and a second section comprising two wires (the said web carrying wire and a looped top or covering wire) facing each other (and between which the forming web is enclosed) and guided conjointlyover a dewatering roll to follow a downwardly curved path while secondary dewatering ensues through the top wire due to centrifugal forces before passage over a suction transfer roll where a first transfer from the bottom (forming) wire to the top wire ensues preparatory to passage over a vacuum transfer box for a second transfer from the top wire to a wet web saturator fabric or a through dryer fabric for delivery o

Abstract: A headbox of a paper machine includes a header chamber for receiving pulp stock, a distribution pipe system for receiving pulp stock from the header chamber, a flow-equalizing chamber for receiving pulp stock from the distribution pipe system, a turbulence passage system for receiving pulp stock from the flow-equalizing chamber, and a lip slice for receiving pulp stock from the turbulence passage system and discharging the pulp stock from the headbox. At least one of the above chambers is defined in part by a movable wall structure which has an inner surface contacting the pulp stock so that this movable wall structure can move in response to pressure fluctuations in the pulp stock. This wall structure has an outer surface which defines part of the hollow interior of an enclosure in which air under pressure is situated, so that through the movable wall structure the air under pressure can act on the pulp stock to damp pressure fluctuations thereof.

Abstract: A paper machine has a headbox provided with a slice through which a pulp suspension discharges from the headbox, this slice being defined in part by an upper lip frame. The pulp suspension flows to the slice from a distribution header and a turbulence passage assembly which receives the pulp stock from the distribution header and continues the flow thereof toward the slice. An air tank is provided for containing air under pressure to act on the flowing pulp stock so as to damp pressure fluctuations in the pulp suspension flow, and this air tank is connected in part to the upper lip frame of the slice so that the pressure in the air tank will act on the pulp suspension in the immediate vicinity of the slice.

Abstract: A papermaking machine having pulp supplied in a regulated excess amount through a feed channel onto a movable water-pervious element and having a sump positioned at the end of the feed channel to receive the overflow. The amount of pulp in the sump relative to the desired overflow rate is used to produce a control signal for regulating the machine. Should there be an excess amount of pulp in the sump over the desired amount, the negative pressure in the vacuum box is increased to withdraw more water. Also, the degree of grinding of the pulp can be varied in dependence on the control signal.

Abstract: The damping device has a transition section of increasing cross-sectional area with a perforated plate extending across the downstream end. The perforated plate has ducts which increase in cross-sectional area in a step-wise manner. The transition section may have a parabolic profile, a conical profile, an arcuate profile or may be formed of a sequence of conical parts.

Abstract: A paper machine has an enclosure for containing a gas under pressure. A hydraulic headbox of the paper machine includes a slice as well as a conductor structure for conducting suspension to the slice and a distributor structure for distributing suspension as uniformly as possible to the conductor structure to be conducted thereby to the slice. The gas enclosure and distributor structure respectively have hollow interior portions communicating with each other so as to provide for the suspension in the distributor portion a free surface acted upon by gas under pressure in the enclosure so that this latter gas under pressure will act as a gas cushion for damping pressure variations in the stock suspension.

Abstract: A method and mechanism for compensating for pressure fluctuations in a paper machine stock flow system for conducting stock from a supply pump to a slice opening including providing a flexible diaphragm as one wall of the stock conduit with the diaphragm dampening pressure variations and being supported on its opposite side by air in an air chamber divided into compartments with a support compartment immediately opposite the diaphragm and a supply compartment behind the support compartment and the compartments divided by an attenuator wall. Air is supplied continuously at a reference pressure to the supply compartment, and a relief valve is positioned in the support compartment with the port opened or closed by movement of the diaphragm so that air is bled from the support compartment as the diaphragm moves toward the stock conduit with a drop of pressure therein.

Abstract: A paper-making machine has a stock supply conduit, a slice, and a pre-slice flow distributing system which communicates with the slice and directs a flow of paper-making stock from the supply conduit to the slice. The system includes a manifold extending longitudinally of the slice, being spaced from the same and having an inlet side through which stock flows from the conduit in direction transversely of the elongation of the manifold. A first side wall of the manifold extends from the inlet side in the flow direction and has a first wall portion which is convex transverse to the flow direction so as to be tangentially approached by the flowing stock and which is formed with a plurality of outlet openings each having a center axis.