Gross machine moisture control system for the net end of a paper machine

Claim 2

In a machine for making a continuous web of paper, the machine including a moisture removing means comprising a wet press section having upper and lower rolls and a drying section, a cross machine moisture control system comprising first, second and third means for providing a first group of signals generally representative of the actual web profile present at a location between said sections, fourth means providing a second group of signals representative of a desired moisture profile, means for comparing said first group of signals with said second group of signals, and means controlled by said first, second, third and fourth means responsive to any error signals produced by said comparing means for relatively adjusting said upper and lower press rolls to remove moisture from said web so as to cause said actual moisture profile to conform more accurately to said desired moisture profile, said first means providing a first signal in said first group of signals relating to actual gross moisture level and said fourth means providing a first signal of said second group relating to desired moisture level, said second means providing a second signal in said first group of signals relating to the skew of the actual profile and said fourth means providing a second signal of said second group of signals relating to the skew of the desired profile, and said third means providing a third signal of said first group of signals relating to the actual profile curvature and said fourth means providing a third signal of said second group of signals relating to the desired profile curvature.

Claim 3

The combination set forth in claim 3 in which said first means includes a scanning moisture gauge for traversing the width of said web at a location intermediate said press and drying sections.

Claim 4

The combination set forth in claim 3 in which said comparing means includes first, second and third summing junctions, said first summing junction comparing said first signals, said second summing junction comparing said second signals, and said third summing junction comparing said third signals.

Claim 5

The combination set forth in claim 5 including a first controller connected to the output of said first summing junction, a second controller connected to the output of said second summing junction and a third controller connected to the output of said third summing junction, said moisture removing means being controlled by said controllers.

Claim 6

The combination set forth in claim 6 including means connected to said first and second controllers for providing a pair of signals having an inverse relationship with respect to each other, said moisture removing means including a pair of actuating mechanisms for controlling the adjustment of said upper and lower press rolls predominantly on the marginal portions of the web, and means connected to said third controller for providing an additional signal, said moisture removing means including an additional actuating mechanism for controlling the adjustment of said upper and lower press rolls predominantly on the central portion of said web, said pair of signals and said additional signal collectively causing said pair of and additional actuating mechanism to remove moisture in a cross machine direction so that the actual profile more closely approaches a desired profile.

Claim 7

The combination set forth in claim 7 in which said pair of actuating mechanisms apply controlled amounts of pressure to the opposite ends of said upper roll and said additional actuating mechanism applies a controlled amount of pressure to the central portion of said lower roll.

Claim 8

In a machine for makinG a continuous web of paper, a cross machine moisture control system comprising means for removing moisture from said web, first, second and third means for providing a first group of three signals generally representative of the actual web moisture profile, said first means providing the first signal of said first group relating to actual gross moisture level, said second means providing the second signal of said first group relating to the skew of the actual profile and said third means providing the third signal of said first group relating to the actual profile curvature, means for providing a second group of three signals generally representative of a desired moisture profile, the first signal of said second group relating to a desired gross moisture level, the second signal of said second group relating to the skew of the desired profile and the third signal of said second group relating to the desired profile curvature, first means for comparing the first signal of said first group with the first signal of said second group to provide a first error signal representative of any difference therebetween, second means for comparing the second signal of said first group with the second signal of said second group to provide a second error signal representative of any difference therebetween, third means for comparing the third signal of said first group with the third signal of said third group to provide a third error signal representative of any difference therebetween, and means responsive to said first, second and third error signals for controlling said moisture removing means in accordance with the respective values of said error signal.

Claim 9

The combination set forth in claim 9 in which said means for controlling said moisture removing means includes first, second and third actuators, means for multiplying said first and second error signals to provide a product signal for controlling said first actuator, means for adding said first error signal and said product signal to provide a summed signal for controlling said second actuator, and means for delivering said third error signal to said third actuator for controlling said third actuator.

Claim 10

The combination set forth in claim 10 in which said moisture removing means includes a pair of press rolls between which said web passes, said first and second actuators controlling the pressure applied to the ends of said press rolls and said third actuator controlling the pressure applied to said press rolls intermediate the ends thereof.

Claim 11

In a machine for making a continuous web of paper, the machine including means for removing moisture from said web, a cross machine moisture control system comprising first, second and third means for providing first signals generally representative of the actual web moisture profile present at a given web location, fourth means providing second signals representative of a desired moisture profile, means for comparing said first signals with said second signals, and means controlled by said first and second means responsive to any error signals produced by said comparing means for relatively adjusting said moisture removing means to remove moisture from said web so as to cause said actual moisture profile to conform more accurately to said desired moisture profile, said first signals constituting a group of three signals and said second signals constituting a group of three signals, said first means providing the first signal of said first group relating to actual gross moisture level and said fourth means providing the first signal of said second group relating to desired moisture level, said second means providing the signal of said first group relating to the skew of the actual profile and said fourth means providing the second signal of said second group relating to the skew of the desired profile, and said third means providing the third signal of said first group relating to the actual profile curvature and said fourth means providing the third signal of said second group relating to thE desired profile curvature.