Abstract: A web-forming section of a paper or board machine has a first web-forming unit with a first fiber layer (W1) formed on a first wire (10); a second web-forming unit with a second fiber layer (W2) formed on a second wire (30); and a couch shoe (39) over a curved deck (40) of which the fiber layers (W1, W2) are guided for joining them together. The second fiber layer (W2) is brought to the couch shoe (39) at an angle (?) of less than 20°, advantageously less than 15° in relation to the approach direction of the first fiber layer (W1). The couch shoe (39) is provided with underpressure and the radius of curvature of its deck (40) is usually larger than the radius of curvature of a guide roll (38) preceding it. By the couch shoe, the fiber layers can be joined together wetter than usual.

Abstract: A web-forming section of a paper or board machine has a first web-forming unit with a first fiber layer (W1) formed on a first wire (10); a second web-forming unit with a second fiber layer (W2) formed on a second wire (30); and a couch shoe (39) over a curved deck (40) of which the fiber layers (W1, W2) are guided for joining them together. The second fiber layer (W2) is brought to the couch shoe (39) at an angle (?) of less than 20°, advantageously less than 15° in relation to the approach direction of the first fiber layer (W1). The couch shoe (39) is provided with underpressure and the radius of curvature of its deck (40) is usually larger than the radius of curvature of a guide roll (38) preceding it. By the couch shoe, the fiber layers can be joined together wetter than usual.

Abstract: A method and apparatus for cutting a paper web (W) in a group of drying cylinders provided with single-wire draw (13) in a paper machine or a finishing machine. The drying wire (13) is separated from the paper web (W) by one or more guide rolls (14a, 14b) thereby creating a open draw (W.sub.0) for the web (W). The cutting of the paper web (W) is carried out at the open draw (W.sub.0) of the web (W). After the open draw (W.sub.0), the drying wire (13) and the web (W) are rejoined on the surface of the following leading or drying cylinder (11). Preferably, two guide rolls (14a, 14b) are utilized whereby the first roll is disposed so that the drying wire (13) supports the web (W) up to the location of the guide roll (14a), which is followed by an open draw (W.sub.0) of the web. The drying wire (13) is returned onto the following leading or drying cylinder (11) with the second guide roll (14b).

Abstract: The invention relates to a twin-wire web former for a paper machine wherein a covering wire and a carrying wire form a twin-wire forming zone between them. A method for dewatering a web is also disclosed. In the invention, water is drained out of a web running through the twin-wire zone through both of the wires. After the twin-wire zone, the web is separated from the covering wire and is transferred on the carrying wire to a pick-up point. In hybrid formers, after an initial single-wire forming zone preceding the twin-wire zone, and in gap formers, after a curved forming zone placed directly after a forming gap, there is a forming shoe provided with a ribbed deck and arranged inside one of the wire loops. This forming shoe is followed by dewatering and web forming units which include forming ribs and are placed inside both of the wire loops. At least one of the dewatering and web forming units is loaded by means of a pressure-hose arrangement.

Abstract: The invention relates to a twin-wire web former for a paper machine wherein a covering wire and a carrying wire form a twin-wire forming zone between them. A method for dewatering a web is also disclosed. In the invention, water is drained out of a web running through the twin-wire zone through both of the wires. After the twin-wire zone, the web is separated from the covering wire and is transferred on the carrying wire to a pick-up point. In hybrid formers, after an initial single-wire forming zone preceding the twin-wire zone, and in gap formers, after a curved forming zone placed directly after a forming gap, there is a forming shoe provided with a ribbed deck and arranged inside one of the wire loops. This forming shoe is followed by dewatering and web forming units which include forming ribs and are placed inside both of the wire loops. At least one of the dewatering and web forming units is loaded by means of a pressure-hose arrangement.

Abstract: The invention relates to a twin-wire web former for a paper machine wherein a covering wire and a carrying wire form a twin-wire forming zone between them. A method for dewatering a web is also disclosed. In the invention, water is drained out of a web running through the twin-wire zone through both of the wires. After the twin-wire zone, the web is separated from the covering wire and is transferred on the carrying wire to a pick-up point. In hybrid formers, after an initial single-wire forming zone preceding the twin-wire zone, and in gap formers, after a curved forming zone placed directly after a forming gap, there is a forming shoe provided with a ribbed deck and arranged inside one of the wire loops. This forming shoe is followed by dewatering and web forming units which include forming ribs and are placed inside both of the wire loops. At least one of the dewatering and web forming units is loaded by means of a pressure-hose arrangement.

Abstract: A method and an apparatus for cutting a paper web (W) in a group of drying cylinders provided with single-wire draw (13) in a paper machine or a finishing machine. The drying wire (13) is separated from the paper web (W) by one or more guide rolls (14a,14b) thereby creating an open draw (W.sub.o) of the web (W). The cutting of the paper web (W) is carried out at the open draw (W.sub.o) of the web (W). After the open draw (W.sub.o), the drying wire (13) and the web (W) are rejoined on the surface of the following leading or drying cylinder (11). Preferably, two guide rolls (14a,14b) are utilized whereby the first roll is disposed so that the drying wire (13) supports the web (W) up to the location of the guide roll (14a), which is followed by an open draw (W.sub.o) of the web. The drying wire (13) is returned onto the following leading or drying cylinder (11) with the second guide roll (14b).

Abstract: The invention concerns a suction roll (10) for a paper making machine, on which the paper web is pressed towards the outer face of the roll mantle. The suction roll (10) is divided, in the axial direction of the roll, into at least three vacuum spaced (A.sub.1, A.sub.2, A.sub.3). In the interior of the suction roll (10), there are at least two partition walls (17a, 17b), by means of which the suction space (13) is divided into separate zones of negative pressure. The lateral vacuum spaces (A.sub.1, A.sub.3) in the suction space can be subjected to a higher negative pressure than the vacuum space (a.sub.2) in the middle area of the roll, whereby the profile of negative pressure is formed such that the negative pressure increases across the width of the roll towards the lateral areas. The invention also concerns a method for producing a desired pressure profile for a suction roll.

Abstract: A method for applying a negative pressure over a sector of an air-pervious mantle of a roll includes providing a suction chamber within the pervious roll mantle which extends over a suction sector of the roll, directing air jets away from the suction chamber at the outermost edge portions of the suction chamber, the air jets causing air currents to be ejected from the suction chamber at the outermost edge zones thereof, the air currents thereby producing air seals at the outermost edge zones of the suction chamber without the use of contact-type sealing elements and at the same time, at least partly, providing a negative pressure in the suction chamber. A suction roll includes blow nozzles for directing air jets away from the suction chamber substantially parallel to the tangent of the roll mantle proximate to the blow nozzles. The inlet sides of the blow nozzles are connected to a pressure chamber situated within the roll mantle, the pressure chamber adapted to be connected to a pressure source.

Abstract: A multi-cylinder drying section and method in a paper machine wherein the paper web to be dried is guided into contact with the surfaces of heated drying cylinders wherein the drying fabric is cooled as it travels from one drying cylinder to the next. According to one embodiment, preferably used in the first group or groups of drying cylinders, a single-fabric draw is used wherein the web is supported on the drying fabric as it runs from the cylinders of one line to the cylinders of the other line so that the web is in direct contact with the surfaces of the drying cylinders in one line while the drying fabric is in direct contact with the surfaces of the cylinders in the other line. The drying fabric is cooled as it runs between the cylinders on which the web is in direct contact with the heated surfaces by causing the drying fabric to come into direct contact with a cooling roll or cylinder surface whose contact area is relatively large.