Method of coating sheet material with an oscillating doctor blade

Abstract

An apparatus for continuously applying a coating to a running web, includes an elastic doctor blade having first and second ends, a frontal side adapted to be oriented towards the web and a reverse side opposite the frontal side and adapted to be oriented away from the web. The apparatus further has a clamping device firmly holding the doctor blade by engagement therewith in a zone of the first end. The clamping device positions the doctor blade for contacting the web at the second end along a scraping line. The apparatus also has an inflatable actuator engaging the reverse side of the doctor blade between the clamping device and the first end of the doctor blade. The actuator has a pressurized state in which a surface portion of the actuator is enlarged by an inflating fluid towards the reverse side of the doctor blade for pressing it against the web. A fluid pressure source is connected to the inflatable actuator. A pressure control device generates in the actuator periodic fluid pressure fluctuations of predetermined frequency and magnitude to impart corresponding oscillations to the doctor blade.

Dependencies are inferred from the claim text.