Apparatus for cleaning a doctor blade

Apparatus for periodically purging contaminants from a coating liquid during a coating operation comprising a container for housing a coating liquid, said container including an opening, a rotatable transfer roll contiguous said opening upon a surface of which the coating liquid is deposited, an elongated doctor blade having a free terminal edge, the longitudinal axis of said doctor blade being disposed generally parallel to the axis of rotation of said transfer roll, said doctor blade edge and transfer roll surface defining an exit gap of a predetermined size whereby the deposited coating liquid is doctored to a desired thickness during the passage of said transfer roll surface past doctor blade edge, means for rotating said transfer roll to move said transfer roll surface past said doctor blade edge, means for periodically increasing the predetermined size of said gap and returning the increased gap size to the predetermined size whereby contaminants otherwise incapable of passing through said gap when of said predetermined size will pass through said gap when of said increased size, means for selectively adjusting the predetermined size of said gap, said gap size increasing means includes means for effecting movement of said free terminal edge away from said transfer roll surface to produce said increased gap size, said movement effecting means including pivotally mounted arm means having opposite ends, one of said arm means ends being in contact with said doctor blade, movable cam means operative through another of said arm means ends to pivot said arm means for varying the size of said gap upon deflection of said doctor blade and said gap adjusting means is carried by said one arm means opposite end.