Paper coating apparatus having a replaceable orifice plate

An improved applicator for applying a coating liquid to a moving web of paper carried through an application zone, wherein said applicator is of the type comprising a body portion defining a chamber therein having an elongate opening thereto extending substantially across and parallel to the web, said chamber for receiving coating liquid and directing the same through said opening into an application zone and onto the web;

• a doctor blade extending from a rear side of said chamber opening substantially across and against the web for metering and leveling coating liquid on the web;
• an orifice plate extending from a front side of said chamber opening substantially across and toward but spaced from the web to define a gap between an upper edge thereof and the web;
• seal means at each opposite side end of said doctor blade and orifice plate for sealing the end spaces therebetween, said application zone being defined between said doctor blade, orifice plate and seal means;
• and means for introducing a copious excess of coating liquid under pressure through said opening and into said application zone to completely fill said zone with coating liquid and to continuously flow coating liquid through said gap to substantially completely and continuously fill said gap with coating liquid to form a liquid seal therein for sealing off the front edge of said application zone, wherein the spacing of said orifice plate upper edge from the web may be controlled to adjust the size of said gap to a selected value, the improvement comprising means for mounting said orifice plate on said applicator for replacement thereof without disassembly of said applicator, said orifice plate being relatively thin and planar, having a length to extend substantially across the web and a selected height between said upper and a lower edge thereof, said mounting means including a front wall on said body portion extending substantially across the web, said front wall having a slot or channel therein extending substantially across the opening toward the web, said orifice plate being transversely extendable into and along said slot from a side end thereof to extend said upper edge thereof out of said slot and toward but spaced from the web to define said gap therewith, and means for releasably securing said orifice plate in said slot, so that to adjust the size of said gap one orifice plate of a first height in said slot may be removed therefrom and another orifice plate of a second and different height may be extended into and releasably secured in said slot, whereby said mounting means permits mounting of orifice blades of selected heights on said applicator to control the size of said gap.