GB1469678A - Method and apparatus for controlling the speed of a printing or coating machine - Google Patents

Abstract

1469678 Controlling the speed of a printing machine LES ATELIERS DE CONSTRUCTIONS MECANIQUES C & A HOLWEG SA 2 Dec 1974 [13 Dec 1973] 52027/74 Heading B6C [Also in Divisions D1 G1 and G3] Apparatus for doing this comprises a printing machine, a drier 4, a source 5 of radiation 6 at least some wavelengths of which are absorbed by residual solvent on web 2, a sensor 7 for transmitted or reflected radiation a continuously operating spectrophotometric analyser 9, a visual 'display' 13 and comparator 11 comparing mean effective values with values preset in data input unit 12, manual means 15 and automatic means 14a controlling a variable speed motor 14 driving the web. Until the speed preset on device 15 or the maximum solvent values are reached, regulator 14a increases the speed of motor 14, measured by tachodynamo 16. Another embodiment includes comparator 17. Comparing signals from device 15 and tachodynamo 16, and whose output is compared with that of comparator 11 in amplifier 18. Regulators (19, 20 and 21, Fig. 2, not shown) may act to control factors such as the temperature or the rate of recycling of tunnel air. Drying speed G = f(V, T, R) where V = air speed, T = temperature and R = recycling rate. To a drying speed G there correspond values of V, T and R which use minimum energy. In the third embodiment, values to be respected, such as the maximum and minimum of V, T and R are set at 23, and information treatment apparatus 22 alters G to suit the production speed and admissible rates of residual solvent and to use minimum energy. The corrections of V, T and R are made by regulations 24, 25 and 26 acting respectively on the heat exchanger 27, the fan drive motor 28 and the air recycling valve 29. Where several machines are used one central analysis apparatus may be switched in cycles to different reading heads.