Improvements in air doctors for coating machines

摘要

An air doctor for coating-machines comprises an elongated nozzle consisting of a large plenum chamber, a throat portion and spaced lip portion forming a slit, at least one lip portion being convex so that a non-divergent stream is produced. The three parts are rectilinear and co-extensive. The casing 1, e.g. of aluminium, forming the plenum chamber is provided at each end with tubular sleeves 3 serving to admit air and acting also as trunnions, carried in arms 5 pivoted at 6 in slides 7 mounted on brackets 8 forming part of the frame of the coating-machine. A screw 12 permits adjustment of the casing 1 relatively to a coating roll 2 and angular adjustment of the nozzle is provided by screws 14 and 16 co-operating respectively with a stop 15 and swivel members 19 and 20. The casing is supported in non-operable position by a stop 27. Plates 30, 31, preferably of phosphor bronze, comprising the nozzle are secured by screws 32, 35 to the casing 1 and plate 30 is adapted to be warped towards plate 31 by providing it with a weakening groove 36. Ball-seated adjusting nuts 39 co-operating with stud bolts 37, or in a modification, screws having heads bearing against plate 30, serve to vary the nozzle orifice. The end walls of the casing 1 are closed by shaped guards 42. Instead of the combination of plane and convex lips, both may be convex. In a modified construction, the casing 1 may be made of a plurality of sections bolted together.