Valmet Oy

Valmet Paper Machinery Inc.

Kymmene Oy

Pekka Eskelinen

Vesa Vuorinen

Raimo Virta

Timo Haverinen

Markku Karlsson

Reima Kerttula

Yngve Lindstrom

Juhani Jokinen

Martti Salmivaara

Seppo Rantanen

Raimo Malkki

Paavo Jaatinen

Timo Vedenpa

Pentti Raatikainen

Jorma Kotanen

Matti Nurmio

Method and device for ensuring the run of the web in the multi-cylinder

Method of and device for pocket ventilation in the drying section of a

A single-wire drying group in a paper machine is disclosed including a plurality of drying cylinders whose axes are situated in a substantially common plane, a drying wire carrying a web between successive drying cylinders, one or more deflection rolls, each situated between a pair of successive drying cylinders and wherein the web-carrying drying wire has an incoming run from a drying cylinder to a deflection roll whereupon the drying wire runs over a deflection sector of the deflection roll and then to a subsequent drying cylinder. A blow box has a wall which defines a gap space with the incoming run of the web-carrying wire and a gas flow is directed through the gap space to induce an under pressure on the incoming run to fix the web on the drying wire. The deflection roll has a perforated shell in the perforations of which an underpressure is maintained to ensure that the web remains in contact with the outer surface of the drying wire as the drying wire travels over the deflection or closed sector of the deflection roll.

Method and apparatus in a paper machine single-wire drying group

The present invention concerns a method in a paper machine for the measurement of air penetrability or permeability of fabrics penetrable by air, in particular of a wire or felt. In the method, the fabric penetrable by air such as a wire is passed over at least one roll, where a positive pressure is formed at an inlet side of the fabric with respect to the roll when the fabric runs and in an inlet nip formed between the moving fabric and a face of the roll, and a negative pressure is formed at an outlet side of the moving fabric with respect to the roll in an outlet nip formed between the moving fabric and the roll face. The positive pressure and negative pressure depend up on the permeability of the fabric penetrable by air. According to the method, at least one device is mounted below the fabric penetrable by air such as a wire, this device being sealed relative to the moving roll face so that an at least partially closed pressure space is formed between the device, the roll face, and the fabric. While the fabric penetrable by air such as the wire moves, the pressure is measured out of the pressure space and the permeability of the fabric penetrable by air is calculated from the measured pressure value. The present invention also concerns a device for carrying out this method.

Method and device for measuring permeability/penetrability of fabric in

A method of and arrangement for resisting formation of undulations in a fiber/water mixture supplied onto a forming wire at an open planar wire section of a paper-making machine include establishing over the wire an air curtain extending over the full breadth thereof, in the region of which the air mass upon the wire is set in motion. The direction of movement of the air mass is the same as the traveling direction of the wire, and the velocity of the air substantially equals the speed of the wire. The air curtain commences on the planar wire section, in the machine direction, only at a given distance from a lip slice of a headbox of the machine, and the air curtain extends along the traveling direction of the web over the planar wire section over a given distance.

Method for resisting formation of undulations in a fiber/water mixture

The present invention concerns a device for generating negative pressure inside a cylindrical roll mantle of a revolving roll. The roll has a roll mantle provided with through-holes, grooves or equivalent apertures and confining a suction chamber in the interior thereof, in which a negative pressure can be generated by suctioning air out of the suction chamber. A suction flow directed towards the suction chamber thereby prevails in the holes, grooves or equivalent apertures of the roll mantle. At least one rotor blower or equivalent is attached to the roll to revolve along with the roll, with an intake side of the rotor being connected to the suction chamber of the roll. The movement of rotation of the roll thereby produces rotary movement of the rotor or equivalent, which in turn generates negative pressure in the suction chamber. Thus, in the arrangement in accordance with the present invention, external equipment of negative pressure or a separate piping system is not needed.

Device for generating negative pressure inside a mantle of a revolving

A twin-wire drying section of a paper machine includes upper and lower rows of drying cylinders, an upper drying wire guided by the upper drying cylinders and upper guide rolls situated between the upper drying cylinders, and a lower drying wire guided by the lower drying cylinders and lower guide rolls situated between the lower drying cylinders. A web is pressed by the upper wire in direct drying contact with the surfaces of the upper drying cylinders and is pressed by the lower wire in direct drying contact with the surfaces of the lower drying cylinders and has a free draw of a certain length between a drying cylinder of one row and a drying cylinder of another row. In accordance with the invention, a vacuum zone in arranged on a run of a drying wire between a drying cylinder and the next guide roll which causes the web to be suctioned against the drying wire so that the length of the free run of the web is substantially shortened. The suction is created by directing air jets in directions opposite to the running directions of the drying wire run and the guide roll which eject air from spaces behind them thereby creating the vacuum zone.

Method and apparatus in a twin-wire cylinder drying section of a paper

A method and apparatus for inhibiting or preventing fluttering in a running paper web in a drying section of a paper machine, such as in the area of a twin-wire draw. Air jets are blown into pockets defined by a wire guide roll and wire itself, such air jets issuing from suitably designed and positioned blow boxes to be directed at the side of the wire supporting the web either in a direction towards or opposite from the running direction of the wire, and also at the side of the wire guide roll not supporting the wire, in a direction of the tangent of the guide roll. An air jet may also be blown into the pocket defined by the wire guide roll and the wire itself, at the side of the wire running free, not supporting any web, such air jet being directed substantially perpendicular to the wire. Fluttering of the paper web and drawbacks resulting from the same, such as wrinkles and breaks in the web, are inhibited or prevented.

Method and apparatus for supporting a web in high-speed paper machines

Apparatus and method for guiding a fibrous web from a press section to a drying section, such as guiding a paper web from the press section to the drying section in a paper-making machine. The apparatus comprises a fetching roll adapted to guide the web passing from the press section onto a drying wire from the drying section passing about the fetching roll, and means for urging the web and drying wire against one another as the web is passed to the drying section, this urging means disposed between the fetching roll and the drying section in a running direction of the web and wire. The method of the present invention comprises passing the web from the press section onto a drying wire passing about a fetching roll, and urging the web and drying wire against each other as the drying wire passes from the fetching roll to the drying section.

Method and arrangement for guiding a paper web from the press section to

In a method for guiding the leader of the web in the drying section of a paper machine, a narrow leader is cut out of the full-width web by water jets, or the equivalent, such as, for example, against a roller of the press section. The leader is guided by a plurality of air jets into a gap between threading ropes and is carried between the threading ropes over drying cylinders. The leader is detached from a rock roller of the press section by a first plurality of air jets and is guided by a second plurality of air jets into connection with a drying wire in the drying section of the paper machine. A third plurality of air jets are directed through the drying wire to the leader supported on the drying wire and detach the leader from the drying wire. Substantially immediately upon detachment of the leader from the drying wire, transverse air jets are directed at the leader and shift the leader into the gap between the threading ropes and move the leader between the threading ropes over the drying cylinders.

Method and device for guiding the leader of the web in the drying

Apparatus for ventilating pockets in a multi-cylinder dryer of a paper machine of the type in which guide rolls are situated in spaces between adjoining drying cylinders and wherein a wire or felt has free runs between the drying cylinders and the guide rolls. With respect to a particular pocket to be ventilated, the apparatus functions to blow air through the inlet or incoming free run of the wire into the pocket with air being removed from the pocket at least partially through the following or outgoing free wire run following the guide roll. The apparatus comprises nozzle apparatus including a nozzle nose situated proximate to the incoming free wire run, at least two nozzles being defined by the nozzle nose which extend transversely to the direction of run of the wire. Air is blown through the nozzles into a space defined by the incoming free wire run facing the nozzles, by the guide roll and by the nozzle nose. In this manner, a positive pressure is generated in an area of the wire over a length of the incoming free wire run by the effect of which air flows within the area through the wire into the pocket. The nozzles are preferably situated at each of the opposite edges of the nozzle nose.

Pocket ventilating apparatus for a multi-cylinder dryer of a paper

Procedure for boosting the ventilation in the hood of a paper machine

The surfaces of cylinders or fabrics moving in the press or drying section of a paper machine induce layers of air along with them, which layers of air produce positive and negative pressures at the pits or nips defined by the fabrics or web and the surface of the cylinder. The positive and negative pressures are detrimental to the mutual support contact between the web and the fabric. A method for eliminating the detrimental positive and negative pressures affects the pressure levels at the nips by blowing air in directions opposite to the direction of travel of the web or fabric passing close to a blowing device, and possibly also opposite to the direction of travel of the cylinder surface. As a result of the blowing of air, air is ejected from the pressurized nips or from spaces placed facing the nips of negative pressure on the opposite side of the running of the web and the fabric. Apparatus for carrying out the method includes a blow box placed in connection with the nip. The blow box is connected to devices producing pressurized air and is provided with one or several nozzle slots. A nozzle slot has a curved nozzle surface at an angle of curvature of about 30.degree. to 70.degree.. The direction of the jets of air blown out of the nozzle slots is turned via the nozzle surface due to the Coanda effect. A planar surface follows the curved nozzle surface and functions as a carrying surface stabilizing the web or fabric.

Method and apparatus for the drying section of a paper machine

An air-directing device for directing air to the multiple cylinder dryer of a paper machine includes members for blowing dry air into the vicinity of the web at those points where the evaporation of water from the web is strongest. This reduces the humidity in such regions and promotes the evaporation of water from the web. The points are the initial parts of the cylinder intervals after contact with the web. The air-directing device is so placed, and its air-blowing members are so disposed and directed, that the air blown out from such members is directed into the clefts defined by the surface of the drying cylinder and the paper web. This achieves a pressure effect in the clefts. The air-blowing members are primarily used in connection with single fabric conduction in pockets on the side of the web to urge the web fast to the fabric and are preferably disposed on a doctor beam or in conjunction therewith.

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Turku, Finland

Pekka Eskelinen