PAPERMAKING MACHINE WITH VARIABLE DEWATERING ELEMENTS ADJUSTED BY COMPUTER CONTROL SYSTEM IN RESPONSE TO SENSORS OF PAPER SHEET CHARACTERISTICS

摘要

An automatic control system for a papermaking machine having a plurality of variable dewatering devices with moveable elements which engage the conveyor carrying the paper stock and are adjusted by electrical operating devices, such as servo motors or solenoid valves, to vary their water removal rate in response to control signals produced by a computer controller. A plurality of sensors are spaced along the path of the paper sheet downstream from the variable dewatering devices to sense the paper sheet characteristics including light transparency and mass, and to apply sensor output signals corresponding thereto to the computer controller. The servo motors have their shafts coupled to adjustment devices for cam mechanisms which adjust the moveable elements of the variable dewatering elements. The variable dewatering elements include a variable angle foil, a variable height blade, a variable width slot Uhle box, and a variable width pickup device, whose moveable elements are adjusted to change their water removal rates. Shaft position encoders on the servo motors or other operating devices produce feedback position signal which are applied to inputs of the computer controller to indicate when the moveable elements reach their desired adjustment positions.