Oy Wartsila Ab

Valmet Paper Machinery Inc.

Sivert Westergard

Dan Eklund

Pekka Koivukunnas

Rauno Rantanen

Markku Grasten

Raimo Tuhkanen

A coater for coating a running paper or carboard web comprises a coating chamber having one side open against the web and means for filling the coating chamber with pressurized coating substance. The coating chamber is limited in the longitudinal direction of the web by a web entrance wall, and opposite thereof, a back wall in the form of a doctor member for forming a coating layer on the web. The distance between the walls is so short that, at normal web running speed, the web moves from the web entrance wall to the back wall in a time of at the most 0.3 s, preferably at the most 0.03 s. Coating substance is supplied by means of positive pressure to the coating chamber at a position close to the web entrance wall. Close to the web entrance wall the flow of coating substance in the coating chamber is divided into two branches, of which a first branch follows the web in its running direction towards the back wall and a second branch, which is considerably greater than the first branch, flows out from the coating chamber through a slot between the web entrance wall and the web.

Coater

A short-dwell coater comprises of a backing roll (1) used for guiding a paper web (1), with an upper lip (28) and a lower lip (28) forming a nozzle apparatus. This nozzle apparatus can apply the coating mix on the paper web while the web is backed by the surface of the backing roll. A doctoring member with which the excess mix applied with the nozzle apparatus can be doctored is also provided as well as a mounting fixture, to which the doctoring member is mounted, and a support structure, with which the fixture is supported. In the short-dwell further comprises an actuator, to which the nozzle apparatus is attached so that the apparatus is movable in relation to the doctoring member in order to adjust the dwell length between the doctoring member and the nozzle apparatus.

Short-dwell coater

An appliance for a double-sided coating of a moving web by means of two coating substance applicators and a smoothing nip comprising a back-up roll on one side of the web and a adjustable levelling blade or the like on the other side of the web. The coating substance is supplied on the web directly on the side facing the levelling blade and on the surface of the back-up roll or the web on the other side of the web. The smoothing nip and the both applicators are located within a 30 degrees sector of the back-up roll, preferably within a 20 degrees sector.

A coater for coating a running paper or cardboard web comprises a coating chamber having one side open against the web and means for filling the coating chamber with pressurized coating substance. The coating chamber is limited in the longitudinal direction of the web by a web entrance wall, and opposite thereof, a back wall in the form of a doctor member for forming a coating layer on the web. The distance between the walls is so short that, at normal web running speed, the web moves from the web entrance wall to the back wall in a time of at the most 0.3 s, preferably at the most 0.03 s. Coating substance is supplied by means of positive pressure to the coating chamber at a position close to the web entrance wall. Close to the web entrance wall the flow of coating substance in the coating chamber is divided into two branches, of which a first branch follows the web in its running direction towards the back wall and a second branch, which is considerably greater than the first branch, flows out from the coating chamber through a slot between the web entrance wall and the web.

Apparatus for coating running webs

A system for two-sided coating of a running paper web. The device comprises an application device for spreading the coating material over both sides of the web running through a first nip formed by a rotating counter roll and a levelling member.

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Jarvenpaa, Finland

Sivert Westergard