Valmet Paper Machinery Inc.

Valmet Corporation

Allan Liedes

Heikki Ilvespaa

Antti Kuhasalo

Juha Kaihovirta

Olavi Viitanen

Jouko Aula

Auvo Saari

Reima Kerttula

Jouko Yli-Kauppila

Markku Karlsson

Ville Korhonen

Risto Lehosvuo

Heikki Ilvesppaa

Pekka Matilainen

A dryer section of a paper machine which is provided with at least one intermediate calendering nip and includes several successively arranged wire groups. The dryer section primarily or exclusively has groups with single-wire draw in which heated drying cylinders are arranged in an upper row and reversing suction cylinders or reversing suction rolls are arranged in a lower row below the upper row. The groups with single-wire draw also have a drying wire which runs along a meandering path over the drying cylinders and reversing suction cylinders or rolls so that the reversing suction cylinders remain inside the loop of the drying wire. A calender roll is arranged in opposed relationship to a drying cylinder in one or more of the single-wire draw groups in a sector which the first face of the web is exposed to thereby define a calendering nip therewith.

Dryer sections with intermediate calendering in a paper machine

A dryer section of a paper machine which is provided with at least one intermediate calendering nip and includes several successively arranged wire groups. The dryer section primarily or exclusively has groups with single-wire draw in which heated drying cylinders are arranged in an upper row and reversing suction cylinders or reversing suction rolls are arranged in a lower row below the upper row. The groups with single-wire draw also have a drying wire which runs along a meandering path over the drying cylinders and reversing suction cylinders or rolls so that the reversing suction cylinders remain inside the loop of the drying wire. Two calender rolls are arranged to form the calendering nip through which a paper web to be dried is passed, and thus calendered inside the dryer section, immediately preceding or following or within one or more of the dryer groups of the dryer section.

A dryer section of a paper machine which is provided with at least one intermediate calendering nip and includes several successively arranged wire groups. The dryer section primarily or exclusively has groups with single-wire draw in which heated drying cylinders are arranged in an upper row and reversing suction cylinders or reversing suction rolls are arranged in a lower row below the upper row. The groups with single-wire draw also have a drying wire which runs along a meandering path over the drying cylinders and reversing suction cylinders or rolls so that the reversing suction cylinders remain inside the loop of the drying wire. In one representative embodiment, at a drying cylinder situated inside the group with single-wire draw or in connection with the last drying cylinder in the group, a free space is arranged in which a calender roll is arranged to form the calendering nip together with the drying cylinder in the group with single-wire draw through which a paper web to be dried is passed and, thus, calendered inside the dryer section.

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).

Method of and apparatus for cutting a lead-in strip of paper web

A method for contact drying a paper web, wherein the paper web is dried by heated smooth-faced drying cylinders by passing the web through successively arranged so-called normal groups with single-wire draw in which drying cylinders are situated in a first row and reversing suction cylinders or equivalent suction rolls are situated in a second row. Thereafter, the web is dried by passing it through a hybrid dryer group which hybrid dryer group consists of a normal portion with single-wire draw and a portion with twin-wire draw, one of the wires in the twin-wire portion constituting the wire of the portion with single-wire draw whereas the other wire in the twin-wire portion is a separate wire. The invention also relates to a dryer section of a paper machine wherein the initial part includes successively arranged so-called normal groups with single-wire draw after which one hybrid dryer group is provided, in which there is a portion with single-wire draw and a portion with twin-wire draw. In the hybrid group, one row includes drying cylinders over which the wire of the single-wire draw runs, and the other row includes reversing cylinders, suction rolls or equivalent, and drying cylinders. A separate wire runs over the drying cylinders in this row.

Method for contact drying a paper web and a dryer section of a paper

A dryer section of a paper machine including cylinder groups provided with single-wire draw having smooth-faced heated drying cylinders against which a web to be dried enters into direct contact, and reversing rolls. The groups with single-wire draw have a drying wire which is guided in a loop by guide rolls as well as by the drying cylinders and the reversing rolls so that the drying cylinders are placed outside the wire loop, and the reversing rolls are situated in gaps between the drying cylinders inside the drying-wire loop. In order to optimize the drying capacity calculated per unit of length of the dryer section in the machine direction, as the drying makes progress, a different ratio of the drying cylinder diameter to the reversing roll diameter is employed, so that, in the first group or groups in the initial end of the dryer section, the ratio is higher than the corresponding ratio in the groups in the middle area of the dryer section. In the group or groups in the final end of the dryer section, a diameter ratio is used that is higher than the ratio in the middle area of the dryer section.

Dryer section of a paper machine including cylinder groups with

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).

Method of and apparatus for cutting a lead-in strip of a paper web

A method in a drying group or groups provided with a single-wire draw in a multi-cylinder dryer of a paper machine in the draw of a web. The multi-cylinder dryer comprises drying cylinders heated by means of steam or equivalent, with the web being pressed by a drying wire against the cylinder faces of these drying cylinders. The multi-cylinder dryer has leading or lower cylinders on which the web runs outside the drying wire which is, for example, a felt. The leading cylinders or rolls are provided with holes passing through a mantle of the leading cylinders or rolls, these holes being fitted to open into an inner space of negative pressure within the leading cylinder or roll and to open, at an opposite end, into grooves provided on a mantle face of the rolls. The negative pressure inside the roll is arranged to be transmitted to the grooves provided on the outer face of the roll mantle, so that an adhesion force is applied to the web through the grooves. In the method, a negative pressure is applied to the entire inside mantle of the roll, and free flow of air is permitted through the holes from an area above the cylinder and into the interior space within the cylinder. The present invention further concerns a device for use in the single-wire draw of the multi-cylinder dryer of the paper machine, and also to a paper-machine cylinder itself.

Method and device for drawing a web through a group of drying cylinders

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.

Suction roll for a paper making machine and a method for producing a

The invention relates to an apparatus for use in the drying section of a paper machine, which apparatus comprises a drying cylinder group formed by drying cylinders and a roll group formed by rolls, preferably suction rolls located at a different height relative to the drying cylinders. The geometric rotational axis of the roll located in an area between two adjacent drying cylinders in a different height position is spaced away from the center plane between the center axes of the drying cylinders. The surface of the roll, preferably a suction roll, is adapted to be located as close to the surface of the drying cylinder on the web outgoing side of the roll as possible, whereby the free transfer distance of the outgoing side is minimized.

Drying section apparatus for a paper making machine

A method in a drying group or groups provided with a single-wire draw in a multi-cylinder dryer of a paper machine in the draw of a web. The multi-cylinder dryer comprises drying cylinders heated by means of steam or equivalent, with the web being pressed by a drying wire against the cylinder faces of these drying cylinders. The multi-cylinder dryer has leading or lower cylinders on which the web runs outside the drying wire which is, for example, a felt. The leading cylinders or rolls are provided with holes passing through a mantle of the leading cylinders or rolls, these holes being fitted to open into an inner space of negative pressure within the leading cylinder or roll and to open, at an opposite end, into grooves provided on a mantle face of the rolls. The negative pressure inside the roll is arranged to be transmitted to the grooves provided on the outer face of the roll mantle, so that an adhesion force is applied to the web through the grooves. In the method, a negative pressure is applied to the entire inside mantle face of the roll, and free flow of air is permitted through the holes from an area above the cylinder and into the interior space within the cylinder. The present invention further concerns a device for use in the single-wire draw of the multi-cylinder dryer of the paper machine, and also to a paper-machine cylinder itself.

Method and device in a drying group or groups provided with a single wire draw, in a multi-cylinder dryer of a paper machine for securing the threading of the web. The multi-cylinder dryer has drying cylinders heated by steam or equivalent, with the web to be dried being pressed by the drying wire into direct contact with cylinder faces of the drying cylinders. The multi-cylinder dryer also has leading cylinders or rolls on which the web remains outside the drying wire. In the area of single-wire draw, the leading cylinders or rolls are provided with a suction zone situated at a side of the service-side end of the rolls. The suction zone is provided by way of perforations passing through a mantle of the leading cylinders or rolls. The negative pressure present in an interior space in the leading cylinders is spread onto the outer faces thereof through the perforations and by way of grooves situated within the area of the suction zone and passing around the roll mantle. The sector of the leading cylinders or rolls that remains free from the drying wire and from the web, is closed over the suction zone by way of an outer closing arrangement.

Method and device for threading a web around drying cylinders

Method and apparatus for guiding and directing an end conduction strip of a web from a smooth-surfaced roll, such as a paper web in a press. The end conduction strip is detached from the smooth surface of the roll and further guided by utilizing a guide plate and air blowing actions. An air jet having sufficiently great impulse is directed against the end conduction strip on the roll surface. The end conduction strip is cut with the aid of this air jet and a leading edge thereof is detached by this air jet from the roll surface. The detached end conduction strip is further guided and conveyed forwardly by a transfer blowing action. This transfer blowing action is directed along the guide plate. An under-pressure field is produced in conjunction with the guide plate, by effect of the blowing action. The effect of this under-pressure field causes the end conduction strip to be further guided in a direction determined by the guide plate.

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Palokka, Finland

Allan Liedes