Basis weight control system for a papermaking machine

Claim 2

The machine and control system of Claim 2 in which said error responsive means includes an integrator which provides a control signal representative of said error signal and the time integral thereof.

Claim 3

A machine for making a continuous web of paper, said machine including a web forming section, a headbox, a stuff box, a basis weight valve between said stuff box and headbox for varying the flow of heavy stock to said headbox subsequently delivered to said web forming section via said headbox, a system for controlling the final basis weight of said paper web comprising means providing a set point signal indicative of a desired basis weight, means providing a feedback signal indicative of the actual final basis weight, first means comparing said desired set point signal with said feedback signal to provide a modified set point signal representing any difference present between said signals, means providing a signal derived from the consistency of heavy stock flowing through said basis weight valve, means providing a signal derived from the rate of flow of heavy stock through said valve, first means for multiplying said consistency signal and said flow signal together to provide a product signal, second means for multiplying said product signal by a signal representative of a selected constant to provide a second product signal, means providing a signal representative of the web speed, means for dividing a second product signal by said speed signal to provide a quotient signal which is representative of the predicted basis weight, second means for comparing said quotient or predicted basis weight signal with said feedback signal to provide an error signal representing any difference present between said predicted and feedback signals, summing means having a pair of input terminals and an output terminal, one input terminal being connected to said dividing means and its output terminal being connected to said second comparing means, means including a servomechanism connected between said second comparing means and the second input terminal of said summing means to provide an adjusted predicted basis weight signal which is a function said error signal in addition to being a function of the consistency of heavy stock, its rate of flow, and the speed of said web forming section and means for controlling said basis weight valve in response to said adjusted predicted basis weight signal.

Claim 4

The machine and control system of claim 4 including a potentiometer connected between said servomechanism and the second input terminal of said summing means, whereby said servomechanism adjusts said potentiometer in accordance with any error signal provided by said comparing means.