A belt assembly for moving a web from a press section (1) of a paper- or board-making machine to a dryer section (3) of the machine, comprises a combination of a first press roll (11) adapted to be arranged at the press section (1), and a stretcher/guiding roll (51) which is arranged between the press section (1) and the dryer section (3). A heat conductive metal belt (5) that forms an endless loop and that is impervious to fluids goes over the first press roll (11) and the stretcher/guiding roll (51), so as to take over a web at the press section (1) and to move the web to the dryer section (3). A guide roll proportional position control is adapted to control the position of the metal belt (5) between the edges of the stretcher/guiding roll (51).

A simple method capable of effectively preventing dry part areas, at least the surfaces of cylindrical dryers, from being stained even if a spray space is absent in a paper machine. The method can prevent the contact part of the dry part (D) of the paper machine with a paper body frombeing stained. The drypart staining prevent ion method can continuously feed/apply a staining inhibitor (T) to the paper body (W) at a position just before the dry parts.

The invention concerns a method and a device in crawling operation of a press felt (H) in a paper machine. The press felt (H) has been passed as a closed felt loop through the nip (N) placed between the centre roll (K) and the press roll (T) in the press of the paper machine, the felt (H) being driven, during the running proper of the paper machine, by means of the nip drive (N) between the centre roll (K) and the press roll (T) of the press. When the paper machine is not being run and the nip (N) between the centre roll (K) and the press roll (T) in the paper machine is open, the felt is moved, so as to moisten the new felt (H), by means of the crawling drive by rotating the drive roll (10). The axle (10a) of the drive roll (10) is permanently connected with a drive rim (20). During crawling operation, the drive wheel (19;27a,27b...) of a hydraulic device (14,17;26a,26b...) is brought into engagement with the drive rim (20), and, when the crawling drive of the felt is not in operation, the drive roll (10) is switched to the free revolving position by shifting the drive wheel (19;27a,27b...) of the hydraulic device (14,17;26a,26b...), which drive wheel is operationally connected with the drive rim (20), apart from the drive rim (20).

A method for forming a paper or paperboard web from a fibrous material in the wire section of a paper making machine or equivalent machine comprising a bottom wire loop (2;102) with the main portion of its top run being horizontal or substantially horizontal, and a top wire loop (10;110) working in conjunction with the bottom wire loop; wherein in the method fibre slurry coming out of the headbox (1;101) of the paper making machine is fed to the first part (2a; 102a) of the top run of said bottom wire loop (2;102), which forms the first dewatering zone after which the partly formed fibre layer is led to the second dewatering zone, in the area of which said top wire loop (10;110) moves to cover said partly formed fibre layer in such a way that water removal from the fibre layer continues it least in two stages in the area of said second dewaterlng zone, whereupon the top wire loop (10;110) is separated from the nearly formed web (W) that is led to follow the run of the bottom wire loop (2;102) forward to the next processing stages of the web (W), wherein the method is characterized in that in the single-wired dewatering zone (2a;102a), after the initial water removal is carried out through the bottom wire (2;102), water removal through the bottom wire (2;102) is prevented by means of an element group (9; 109) operating in contact with the inner surface of the horizontal top run of the bottom wires; that in said water-removal pre­vention area water is removed from the web (W) through the top wire in the first stage or stages of the double-­wired second dewatering zone, which stages comprise a relatively long, planar wire table extending from the headbox to the forming roll (6 in Fig. 1), or from the headbox to the last supporting element (109 in Fig. 2); and that after the first dewatering stage or stages of the double-wired zone water is removed in a curved double-­wired dewatering zone (b) (Fig. 1) or zones (R_o, C) (Fig. 2), after which the web (W) is led to follow the bottom wire (2;102).

All of the essential operating parts for adding a top former assembly to a new Fourdrinier paper machine or for converting an existing Fourdrinier paper machine into a top former are carried by a supplemental frame assembly (100) which can be mounted on the main Fourdrinier frame (10) with minimal modification of the latter except the addition of simple parts for securing the supplemental frame assembly on top of the main frame. The primary operating parts of the top wire assembly are a hollow open faced roll (125) and a top wire deflector (150) which cooperate to collect and deliver liquid expressed through the top wire (110) into a receptacle (195) that is carried by the supplemental frame assembly, and special provision is made for utilizing the top wire deflector to correct for irregularities in the cross machine profile of the paper sheet as it is being formed. Provision is also made for operating the resulting top former in roll former mode, blade former mode, or a combination roll and blade former modes.

A forming roll positioned in the forming section of a Fourdrinier papermaking machine and supported above the forming medium in contact with one surface of a constituent material to sandwich the material between a substantial arc segment of the forming roll surface and the forming medium.

An apparatus for dewatering a fibrous suspension comprises a suction housing (7) which has an active surface (9) by means of which water is extracted upwardly from the fibrous suspension which is trapped between top and bottom wires (1, 5).

In orderto provide a more efficient means of dewatering, the active surface (9) has a first open area (15) by means of which water is removed upwardly by suction, and a second part (17) downstream of the first, which urges water downwardly. The second part (17) is conveniently a solid surface. The first part of the active surface is preferably curved with a radius which decreases in the downstream direction.

Apparatus for dewatering a fibrous suspension on a paper forming machine comprises a suction housing (7) having a convexly curved active surface (9) adapted to contact a travelling forming wire (1) of the paper machine. Suction and pressure is applied to the fibrous suspension over the length of the active surface (9) for the purpose of dewatering the suspension.

In order to increase the drainage capabilities of the dewatering apparatus the upstream radius (R1) of curvature of the active surface (9) is arranged to be greater than the downstream radius (R3) of curvature to thereby increase the pressure applied to the web over the length of the active surface. In one embodiment the active surface has three discrete radii R₁, Rs, R₃ in which R₁>R₂>R₃. In another embodiment the radius increases progressively.