Valmet Oy

Timo Vedenpaa

Pekka Mauranen

A method and apparatus for cutting a lead-in strip from a paper web in a multiple cylinder dryer section of a paper machine and for increasing the width of the lead-in strip by a so-called oblique draw. A cutting device for cutting the web is situated alongside a region of an unsupported draw of the web in the dryer section. According to the method, and apparatus a guide surface which extends in substantially parallel relationship to the plane of the web is associated with the web cutting device. A gas flow is directed over the guide surface to stabilize the run of the web during the cutting operation performed on the web by the cutting device. The gas flow is directed onto the guide surface from a nozzle opening situated adjacent to the leading edge region of the guide surface into a space between the guide surface and the web to produce an underpressure in the space which stabilizes the web run. Alternatively, two gas flows are directed from respective leading and trailing edge regions of the guide surface toward each other onto the guide surface into the space between the web and the guide surface to stabilize the web by means of an overpressure created in the space.

Method for cutting a lead-in strip from a paper web in a paper machine

A method and apparatus for cutting a lead-in strip from a paper web in a multiple cylinder dryer section of a paper machine and for increasing the width of the lead-in strip by a so-called oblique draw. A cutting device for cutting the web is situated alongside a region of an unsupported draw of the web in the dryer section. According to the method and apparatus, a guide surface which extends in substantially parallel relationship to the plane of the web is associated with the web cutting device. A gas flow is directed over the guide surface to stabilize the run of the web during the cutting operation performed on the web by the cutting device. The gas flow is directed onto the guide surface from a nozzle opening situated adjacent to the leading edge region of the guide surface into a space between the guide surface and the web to produce an underpressure in the space which stabilizes the web run. Alternatively, two gas flows are directed from respective leading and trailing edge regions of the guide surface toward each other onto the guide surface into the space between the web and the guide surface to stabilize the web by means of an overpressure created in the space.

Apparatus for cutting a lead-in strip from a paper web in a paper machine

Cylinder dryer for paper machine or equivalent

A paper machine multiple cylinder dryer includes a plurality of drying cylinders, in conjunction with which a drying fabric supports the web as it moves from one cylinder to another in closed conduction. A supporting fabric supports the web on some of the cylinders. The runs of the web supported by the drying fabric, the free surfaces of the drying cylinders and the runs of the supporting fabric confine elongated pockets in conjunction with the cylinders. In order to prevent web breaks occurring in the drying section of the fast-running paper machine, since such breaks are among the most important factors limiting the increasing of paper machine speeds, the multiple cylinder dryer provides a pressure greater than the ambient atmosphere pressure in the pockets in the direction of travel of the web, at least in the initial part of the dryer. This results in the considerable stabilization of the running of the web. One manner of producing the over-pressure is to partially or totally close both ends of the pockets with particular closing plates.

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Jyvaskyla, Finland

Timo Vedenpaa