| 摘要 |
700,121. Printing processes. COATES BROS. & CO., Ltd., and BLACK, D. J. Jan. 21, 1952 [May 25, 1951], No. 12332/51. Class 100 (2) Damping apparatus.-A roller 1 for use in lithographic printing apparatus as a scavenging roller and for applying moisture to the damping roller has a bimetal surface consisting partly of an ink-receptive metal, e.g. copper or brass, and partly of a water receptive and, when damp, ink repellant metal, e.g. chromium, chromium alloy, or a tin-nickle alloy 2, the surface areas of the two metals being such that the damping roller is contacted by both metals in the course of four or five revolutions. Preferablv the damping roller contacts the water-receptive metal once for each 1-4 times it contacts the ink receptive metal. The roller may be formed by coating a copper roller with chromium and etching or turning away the chromium except on the parts where it is required or by coating a copper roller with chromium only in those parts. The two metals may form a chequered longitudinal stripe or helical pattern. Specification 488,444 is referred to. |
