Floating doctoring apparatus

An apparatus for at least one of scraping and metering a coating medium on a moving operating surface having a width, said apparatus comprising:

• a doctoring assembly including a metering rod having a surface extending substantially across the width of the operating surface, said surface of said metering rod being configured for being pressed against the operating surface;
• a doctoring support beam supporting said doctoring assembly in a direction transverse to the operating surface, said doctoring support beam being configured for being disposed a predetermined distance from the operating surface, said doctoring support beam having a set of inner walls, said set of inner walls defining a pressurizable chamber;
• a power supply unit configured for exerting a force onto said doctoring assembly to thereby produce a contact pressure between said surface of said metering rod and the operating surface, said force having a flow path, said power supply unit being fluidly coupled with said pressurizable chamber;
• and
• a compensation device disposed in said flow path of said force between said doctoring support beam and said doctoring assembly, said compensation device being configured to compensate for deviations of said predetermined distance between said doctoring support beam and the operating surface to thereby maintain said contact pressure between said surface of said metering rod and the operating surface at a substantially constant level, said compensation device comprising a pneumatic compensation device, said compensation device includes a power assembly having a pressure applying area configured for being activated by a pressure medium to thereby allow said force to be exerted upon said doctoring assembly, said pressure applying area having an effective size substantially independent from said deviations of said predetermined distance between said doctoring support beam and the operating surface said apparatus further comprising a pressure medium supply arrangement configured for regulating and maintaining said pressure medium at a substantially constant pressure, said substantially constant pressure of said pressure medium being exerted on said pressure applying area of said power assembly said power assembly including a piston-cylinder arrangement having a cylinder housing and a piston arrangement, said cylinder housing having a cavity, said piston arrangement having at least one moving piston disposed in said cavity of said cylinder housing, said cavity including a pressure chamber connected to said pressure medium supply arrangement.

An apparatus for application of a coating medium onto a moving fiber material web having a width, said apparatus comprising:

• a doctoring assembly including a metering rod having a surface extending substantially across the width of the fiber web, said surface of said metering rod being configured for being pressed against the fiber web;
• a doctoring support beam supporting said doctoring assembly in a direction transverse to the fiber web, said doctoring support beam being configured for being disposed a predetermined distance from the fiber web, said doctoring support beam having a set of inner walls, said set of inner walls defining a pressurizable chamber, said pressurizable chamber opening toward said doctoring assembly;
• a power supply unit configured for exerting a force onto said doctoring assembly to thereby produce a contact pressure between said surface of said metering rod and the fiber web, said force having a flow path said power supply unit being fluidly coupled with said pressurizable chamber;
• and
• a compensation device disposed within said pressurizable chamber in said flow path of said force between said doctoring support beam and said doctoring assembly, said compensation device being configured to compensate for deviations of said predetermined distance between said doctoring support beam and the fiber web to thereby maintain said contact pressure between said surface of said metering rod and the fiber web at a substantially constant level, said compensation device being mechanically coupled with said doctoring assembly.