Valmet Paper Machinery Inc.

Valmet Corporation

Martti Hirsimaki

Juha Kivimaa

Mikko Karvinen

Juhani Pajula

Pekka Taskinen

Lauri Suvanto

Jouko Villa

Jorma Lapotti

The invention relates to a device and method in a paper machine for guiding a web and in particular in guiding a leader of the web. The device operates in a paper machine in the area between a center roll of the press section and a separate press nip in the press section. The separate press nip is formed between a smooth-faced upper roll and a hollow-faced lower roll. Around this lower roll, a lower felt of the separate press is placed and runs from a suction-transfer roll placed at the proximity of the center roll as a straight run into the separate press nip. At the initial end of the straight run of the felt of the separate press nip, in connection with the guide roll, air-transfer devices are arranged, by whose means a reduced pressure is produced at least across the width of the leader in connection with a closing inlet nip between the felt and the leader and/or in connection with an opening outlet nip defined between the guide roll and the straight run of the felt.

Method and device for guiding a leader of a web in a paper machine

A press section in a paper machine including a first press nip formed between an upper roll and a lower roll whereby a paper web to be dewatered is passed through the first press nip on support of two press felts. The press section includes at least a second and a third press nip formed in connection with a smooth-faced center roil. A press felt is passed through the second and third press nips formed in connection with the center roll. The lower roll in the first nip is a metal-mantle lower roll which has a diameter substantially larger than the diameter of the upper roll in the first nip.

Press section in a paper machine

The invention relates to a device in a paper machine for guiding a web and in particular in guiding a leader of the web. The device operates in a paper machine in the area between a center roll of the press section and a separate press nip in the press section. The separate press nip is formed between a smooth-faced upper roll and a hollow-faced lower roll. Around this lower roll, a lower felt of the separate press is placed and runs from a suction-transfer roll placed at the proximity of the center roll as a straight run into the separate press nip. At the initial end of the straight run of the felt of the separate press nip, in connection with the guide roll, air-transfer devices are arranged, by whose means a reduced pressure is produced at least across the width of the leader in connection with a closing inlet nip between the felt and the leader and/or in connection with an opening outlet nip defined between the guide roll and the straight run of the felt.

Device for guiding a leader of a web in a paper machine

Method and device in the manufacture of paper or board for dewatering of a paper web that is being manufactured. The paper web is transferred from a forming wire onto a wire in the drying section while constantly on support of a fabric that receives water, a transfer fabric, or of any other, corresponding transfer surface as a closed draw, at a particularly high speed, which is higher than about 25-30 m/s. Dewatering of the paper web is carried out by means of at least two subsequent press nips, of which nips at least one press nip is a so-called extended-nip zone, whose length in a machine direction is larger than about 100 mm. The extended-nip zone is formed in connection with a mobile flexible press-band loop. The distribution of the compression pressure employed within said extended-nip press zone is regulated and/or selected both in the transverse direction of the web and in the machine direction so as to set or to control the different profiles of properties of the web.

Method for dewatering of a paper web by pressing using an extended nip

The invention relates to a method and device in the crawling operation of a press felt in a paper machine. The press felt is passed as a closed felt loop through a nip defined between a center roll and a press roll in a press section of the paper machine. The felt is driven during the running operation of the paper machine by means of a nip drive between the center roll and the press roll of the press. When the paper machine is not operating, and the nip between the center roll and the press roll in the paper machine is open, the felt is moved, so as to moisten the new felt, by means of the crawling drive by rotating the drive roll. An axle of the drive roll is permanently connected to a drive rim. During the crawling operation, a drive wheel of a hydraulic device is brought into engagement with the drive rim. When the crawling drive of the felt is not in operation, the drive roll is switched to the free revolving position by shifting the drive wheel of the hydraulic device apart from the drive rim. The drive wheel is operationally connected to the drive rim.

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Jyska, Finland

Martti Hirsimaki