Abstract:
The invention relates to a device for cleaning a moving transport belt in a papermaking machine, for instance a dry or wet wire belt or a felt belt, having at least one nozzle which can be directed against the transport belt for spraying the woven belt with liquid or gaseous fluid. A suction chamber 18 surrounds and cooperates with the cleaning nozzle (8), so that dirt and/or water mist detached by the nozzle jet (27) from the transport belt (4) or residual water are drawn into the suction chamber (18) and led away, avoiding dirtying or contamination of the nearby area.
Abstract:
Several embodiments of an apparatus for applying a liquid or pasty medium e.g. a coating medium onto a moving material web of paper or board are disclosed. All embodiments include a first flexible endless loop belt having an inner surface that passes in contact with a sliding surface of a concave pressing shoe and an outer surface which contacts and moves a web through a press nip. In some embodiments, there is an opposing roll rotating along with the endless belt through the nip. Various devices can apply liquid or pasty medium onto the surface of the belt or the surface of the opposing roll. In an alternate apparatus, there are two counter rotating flexible endless belts which form the press nip between them through which the web is guided. The belts are pressed against each other by elongate guiding surfaces of respective pressing shoes inside the loops of the belts. These embodiments provide a longer length nip in the web travel direction to avoid film splitting during coating of the material web.
Abstract:
A drying section includes a plurality of single-tier dryer groups, optionally followed by one or more double-tier groups. To control curl in the final paper product, a moistening device extending over the width of the drying section is provided near the end of the single-tier dryer groups. The moistening device can be divided into various zones to control the profile of the paper. Alternatively, or in addition to the moistening device, a contact-less dryer such as a infrared dryer can be provided after the dryer section, upstream of a calender section of the paper making machine. The moistening device can be provided to moisten the bottom or, optionally, the top side of the paper web. Where a double-tier dryer group is provided, to control curl the upper drying cylinders and the lower cylinders can be provided with different steam pressures to control curl. Alternatively, each of the cylinders can be individually controlled.
Abstract:
The twin-wire former serves for the production of a web of paper or board. Two wire belts (endless wire loops 11 and 12) form a twin-wire zone with each other. Within the twin-wire zone, the one wire belt (12) travels over rigid ledges (28', 28) which are arranged spaced apart from each other on a water-removal box (18). Within the twin-wire zone, furthermore, the other wire belt (11) travels over several ledges (27) which lie opposite the rigid ledges (28), are supported by means of resilient elements (springs 24, pneumatic pressure cushions, or the like), and can be pressed with a selectable force against the other wire belt. Within one of the wire loops (for instance 11), bridging at least two of the ledges (27) present there, a closed wire support surface (9) is provided. A secondary headbox (10') can be arranged in front of the closed wire support surface (9).
Abstract:
A wire or felt forming section of a paper-making machine has breast rollers for guiding a respective one of two forming wires. The two rollers are disposed with a pulp gap formed between the two rollers and the wires are disposed just downstream of a pulp suspension ejecting nozzle of a headbox. Each roller is supported against the respective taut forming wire by a hydrostatic bearing. The hydrostatic bearing has two circumferentially separated resiliency chambers provided in a combined region of resiliency disposed over an arc of the circumference of the roller. A sealing strip after the region of resiliency prevents fluid from contacting the wire.
Abstract:
A process for drying a paper web and a drying section of a paper making machine. The drying section includes at least one drying group comprised of a plurality of drying cylinders, each at least partially wrapped by a web to be dried. The drying cylinders having peripheral surfaces heated for drying the web moving therepast. The peripheral surfaces of the drying cylinders in the drying groups are rotated at the velocity of the web along the web path. At least one of the drying cylinders in at least one drying group is driven to rotate at a speed that is different than the speed of the web moving past the at least one cylinder. The at least one cylinder may be selectively driven to rotate faster or slower than the speed of the web moving therepast, which applies more heat to the paper web. The invention is adaptable for a single tier drying section and/or for a double tier drying sections or for other drying section arrangements. The operation of a drying cylinder at a different speed than the other cylinders is useful for one or more than one drying cylinder in a drying group and where a drying section is comprised of more than one drying group, is useful for a drying cylinder in one or more of the drying groups.
Abstract:
A coating process for coating traveling webs comprises applying a first coating layer of a pigment substance on a portion of the shell surface of a rotatable roll not covered by the material web, and pressing the pigment substance onto the web in a press gap, thereby impregnating the web. This makes it possible to apply with maximum uniformity and without web breaks and wrinkles a second coating layer of a pigment substance immediately successive to the application of the first layer, while the first layer is still moist.
Abstract:
A doctor bar consists of two different circular disks that are clamped or fixed in some other way on a cylindrical carrier bar. Circular disks having a smaller diameter and made from elastic material alternate with circular disks that have a larger diameter and are made of a very wear-resistant material, specifically ceramic. The difference in the outside diameter makes for one-half the groove of peripheral grooves of the doctor bar that are formed between the various circular disks.
Abstract:
In order to clean the support region at the bottom end of a doctor element which is clamped to a support and is thereby held to the surface of spreadable material to be doctored, the leaf spring doctor element is removable from a stop on the support against which the leaf spring is clamped in operation by a plate pusher. The support is shaped to have a groove extending along the width of the stop and the support for the doctor element. A sidewall of the groove is defined in a ledge that is movable along the support and along the groove. The sidewall supports oscillation pulse transmitters. A liquid pulse transmitting medium in the groove transmits the oscillations across the grove to the area of the leaf spring support to be cleaned. The oscillation pulse transmitters may be a series of transmitters extending along the sidewall along the groove or may comprise a long bar shaped oscillator which is oscillated at its ends. Bearing pedestals at spaced intervals corresponding to the oscillation nodes may support the bar shaped oscillator.
Abstract:
A doctor bar consists of two different circular disks that are clamped or fixed in some other way on a cylindrical carrier bar. Circular disks having a smaller diameter and made from elastic material alternate with circular disks that have a larger diameter and are made of a very wear-resistant material, specifically ceramic. The difference in the outside diameter makes for one-half the groove of peripheral grooves of the doctor bar that are formed between the various circular disks.