Valmet Oy

Martti Pullinen

Erkki Koski

Jouni Koskimies

Martti Koponen

Juhani Niskanen

Method in an adjustable-crown roll, in which a series of hydraulic loading elements is used. A central axle of the roll is supported by axle journals, by means of deflection bearings. A cross-section of the central axle is shaped such that the axle has sufficiently high rigidity in a nip plane. In the method, the central axle is rotated about its deflection bearings over an angle, which may be within the range of about 30.degree. to 180.degree.. A free space that is created or enlarged between the central axle and a roll mantle thereby, and provided between the central axle and an inner surface of the roll mantle, is utilized as an opening gap for the nip formed by the variable-crown roll, by allowing the roll mantle to be shifted, e.g. by the effect of gravity, or by affirmatively shifting the mantle relative to the rotated central axle.

Method and device in an adjustable-crown roll

Apparatus for coating a web, such as paper or board web, comprises a coating nip formed between a rotating counter roll and a smoothing member, or between two smoothing members, through which the web to be coated is passed with a coating substance being applied to the web before it passes through the nip. The apparatus comprises an arrangement by which the linear load and/or the distribution of the linear load in the coating nip is adjustable to control the quantity and/or the distribution of the quantity of the coating substance applied to the web in the transverse direction thereof. A smoothing member comprises an elongate member extending transversely to the direction of web movement through the apparatus and is flexible with respect to its longitudinal dimension so that the profile of the load distribution in the nip can be adjusted to be relatively steep, i.e, the load in the nip may differ relatively widely at points which are relatively close to each other. An arrangement is provided for selectively variably adjusting the load applied to the smoothing member along its longitudinal dimension.

Apparatus for coating a web

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

A forming shoe in a two-wire forming section of a paper making machine has a curved guiding surface which guides a joint run of the wires and web interposed therebetween over a curved path of travel wherein the web is dewatered under the effect of the pressure between the wires at least in a direction away from the forming shoe, the dewatering action being assisted by the curvature of the forming shoe due to centrifugal forces. According to the invention, the length of the active portion of the forming shoe guiding surface, the surface quality or characteristics of the guiding surface and/or the radius of curvature of the guiding surface are adjustable so that web formation and the dewatering capacity of the forming shoe are controlled. For this purpose one or more devices are coupled to the forming shoe by which the attitude and/or location thereof is adjustable. In one embodiment a device is provided between the frame of the forming section and that of the forming shoe for pivoting the forming shoe about a horizontal axis and/or displacing the forming shoe linearly with respect to the vertical and/or horizontal plane.

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Jyvaskyla, Finland

Martti Pullinen