Valmet Oy

Martti Koponen

Erkki Koski

Jouni Koskimies

Martti Pullinen

Olli Tapio

Risto Turunen

Pertti Soikkanen

Jorma Hujala

A web-forming method is applied in a paper machine. The web-forming section which includes a lower wire loop having an initial single-wire run and dewatering zone in which the web is dewatered through and an upper wire loop having a joint run with a subsequent run of the lower wire to form a two-wire dewatering zone within which dewatering takes place substantially through the upper wire. A first open faced forming roll is situated within the upper wire loop so that the two-wire dewatering progress begins upwardly in the region of the first forming roll. A forming shoe within the lower wire loop has a curved deck whose center of curvature is situated on the side of the lower wire loop and further guides the joint run of the upper and lower wires in the two-wire dewatering zone. A second forming roll situated within the lower wire loop after the forming shoe guides the joint run of the upper and lower wires over a downwardly curved sector thereof. According to the method, initial dewatering occurs in the single-wire dewatering zone through the lower wire. In the two-wire dewatering zone, within the range of the first and second forming rolls and the forming shoe situated therebetween, dewatering occurs first within the sector of the first open forming roll in two directions through both the upper and lower wires and primarily through the upper wire. The web is thus substantially dewatered whereupon within the region of the forming shoe, further dewatering takes place primarily upwardly through the upper wire and thereupon the dewatering pressure is further increased within the range of the second forming roll while dewatering continues to take place substantially through the upper wire.

Web-forming method in a paper machine

A web-forming section and method in a paper machine. The web-forming section includes a lower wire loop having an initial lower wire run constituting an initial single-wire dewatering zone of the web-forming section in which the web is dewatered through the lower wire, and an upper wire loop having a joint run with a subsequent run of the lower wire to form a two-wire dewatering zone of the web-forming section within which dewatering takes place substantially through the upper wire. A first open faced forming roll is situated within the upper wire loop so that the two-wire dewatering zone begins and curves upwardly in the region of the first forming roll. A forming shoe within the lower wire loop has a curved deck whose center of curvature is situated on the side of the lower wire loop and further guides the joint run of the upper and lower wires in the two-wire dewatering zone. A second forming roll situated within the lower wire loop after the forming shoe guides the joint run of the upper and lower wires over a downwardly curved sector thereof. According to the method, initial dewatering occurs in the single-wire dewatering zone through the lower wire. In the two-wire dewatering zone, within the range of the first and second forming rolls and the forming shoe situated therebetween, dewatering occurs first within the sector of the first open forming roll in two directions through both the upper and lower wires and primarily through the upper wire. The web is thus substantially dewatered whereupon within the region of the forming shoe, further dewatering takes place primarily upwardly through the upper wire and thereupon the dewatering pressure is further increased within the range of the second forming roll while dewatering continues to take place substantially through the upper wire.

Web-forming section in a paper machine

In a paper making machine, transfer apparatus for guiding a paper web from the press section to the drying section includes a smoothing press including upper and lower smoothing press rolls wherein the web is passed from the press section to the smoothing nip either directly or guided by a guide roll. The lower smoothing press roll of the smoothing press is substantially situated at a position which is normally occupied by a so-called baby or lead-in cylinder of a conventional drying section and the drying wire of the drying section is guided over a sector of the lower smoothing roll which is of a size sufficiently large that the web is transferred onto the drying wire which then carries the web as a closed draw onto the first drying cylinder of the drying section and, preferably, to the subsequent drying cylinders as a so-called single-fabric draw.

Transfer arrangement for guiding the paper web from the press section of

An improvement in a web-forming section of a paper machine intended as a modernization of a fourdrinier-wire part by which an improved formation of the web and an adjustable dewatering thereof by which better retention and desired distribution of fillers and fines is achieved. The web-forming section constitutes an improvement in an arrangement which includes a fourdrinier wire loop having a wire run which constitutes a lower wire of the web-forming section and which forms a single-wire initial portion of a dewatering zone of the web-forming section, and an upper wire unit which together with a run of the lower wire forms a two-wire dewatering zone within which dewatering takes place through the upper wire, wherein a first open faced forming roll is situated within the upper wire loop so that the two-wire dewatering zone begins in the region of the first forming roll, a horizontal plane tangent to the lower part of the first forming roll being substantially coplanar with the plane of the lower wire, a forming shoe within the fourdrinier wire loop having a curved deck which guides the joint run of the upper and lower wires, a reversing roll situated within the upper wire loop after the forming shoe and which guides a joint run of the upper and lower wires over an upwardly curved sector thereof until the joint run substantially coincides with the plane of the lower fourdrinier wire. Initial dewatering occurs in the single-wire initial portion of the dewatering zone to an appropriate extent through the lower wire. In the two-wire dewatering zone, dewatering occurs first within the sector of the first open forming roll in two directions through both the upper and lower wires whereupon within the region of the forming shoe, the dewatering takes place primarily upwardly through the upper wire.

Web-forming section of a paper machine intended for modernization of a

A paper machine drying section has a pair of staggered rows of rotary dryer cylinders which include a first group of cylinders of both rows which form an initial part of the drying section where a web is initially received from a press section. A first endless fabric which forms a closed loop is guided around the above group of cylinders in a manner situating the cylinders of one of the rows within the loop to form inside cylinders therefrom and the cylinders of the other of the rows outside of the loop to form outside cylinders therefrom, this first endless fabric transporting a web which is to be dried around the cylinders of the above group while situating the web between the first endless fabric and the outside cylinders and the first endless fabric itself between the inside cylinders and the web. A second endless fabric structure is pressed against the web only at the portions thereof which lap the inside cylinders for preventing the web from being displaced by centrifugal force outwardly away from the inside cylinders, a suitable speed-control being connected with the second endless fabric structure to provide for the latter a speed of travel according to which the portions of the second endless fabric structure which lap the inside cylinders have an angular velocity substantially equal to the angular velocity of the inside cylinders.

Paper machine drying section and method of operating the same

A machine for manufacturing paper, such as tissue paper, includes a twin-wire former made up of a rotary forming roll and a pair of endless fabrics, each of which may be a wire or felt, lapped around the rotary forming roll to provide twin-wire web formation therewith. At the location where these endless fabrics travel beyond the forming roll they diverge from each other to define between themselves a diverging space where one of the endless fabrics has an upwardly directed surface on which the web is carried beyond the forming roll. This latter endless fabric carries the web to a press section where this latter endless fabric travels with the web through a first press nip of the press section defined between an inner press roll situated within the loop of the latter endless fabric and an outer press roll situated outside of the latter loop. This outer press roll is lapped by an additional endless fabric structure so that the web is situated at the first press nip between the latter additional fabric structure and the endless fabric which carries the web away from the forming roll. The web travels with the additional fabric structure around the outer press roll, to become detached from the endless fabric which carries the web away from the forming roll, and this outer press roll cooperates with a drying cylinder of a drying section of the paper machine to define therewith at least a second press nip.

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Jyvaskyla, Finland

Martti Koponen