GB1453054A - Apparatus for detecting and controlling roll hardness of a continuous web of paper material fuel injection apparatus for internal combustion engines - Google Patents

Abstract

1453054 Automatic control of paper-making CONSOLIDATED-BATHURST Ltd 29 Jan 1974 [30 Jan 1973] 4573/73 Heading G3R The reel hardness of a continuous paper web material is controlled by transversely scanning the web to derive a series of measured values of the hardness, integrating or summing to produce an average value for each of a plurality of transverse segments, comparing an electrical signal representing this value with a reference value, and using the result to actuate devices which cause the hardness to vary. As shown, a paper-making machine includes a stack of calendar rolls 16 between which a web passes to form a wound reel 24. A known Piezoelectric hardness testing device 66 is scanned across the reel, transmitting measured values corresponding to successive positions in a series of segments across the reel width. A computer 50 receives the measured values, integrates, averages and filters corresponding electrical signals for each segment, and compares the resulting signals with stored values representing a desired profile of hardness across the reel. The error signal produced may be processed to form a control signal of error squared plus derivative, PI, PD, PID or other type in accordance with stored algorithms. This control signal actuates rotary valves 32 to control pneumatically through a pressure regulator 28, the settings of valves in distribution nozzles 18 located across the width of calendar rolls 16 and adapted to direct air at a controlled temperature on to the web so as to cause the reel hardness to vary in such a manner as to reduce the error signals. The system may operate in a continuous or incremental mode, using analog or digital techniques. Other properties besides hardness which may be measured and controlled in a similar manner are web thickness, compressibility, smoothness, opacity and porosity.