Curtain coating assembly for paper or carton web has jet discharge slit regulated by a linie of re-circulating ball screw adjustment mechanisms

摘要

An assembly applies an emulsion coat to one or both sides of a paper web. The emulsion is released through a transverse slit with lips (5, 6) as a curtain jet. The jet gap width is varied by an adjustment mechanism (10) acting on one of the lips via a re-circulating ball screw (11). The circulating ball screw mechanism is coupled to a step motor that advances in steps of less than 1 m in conjunction with a harmonic drive gear. The assembly incorporates a number of re-circulating ball screws at intervals of 80 to 120 m. The lips are set at a gap of between 200 and 500 m.