US3634187A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Continuously controlling the basis weight of paper by a timed basis weight valve position signal
Assignee: OI Glass Inc
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Filing: 1969-12-18
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Granted: 1972-01-11
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Expires: 1989-12-18
Abstract
Abstract Method and apparatus for controlling the basis weight of paper and the like whereby the basis weight of the paper from a papermaking machine is measured by scanning the paper with a gamma gauge. The gamma gauge develops corresponding analog outputs which are converted to digital equivalents. A digital computer from these digital equivalents determines the difference between the measured average basis weight and the desired basis weight, introduces various compensating factors, and then develops a timed valve position signal. This valve position signal through a valve operator adjusts the machines pulp slurry or papermaking stock control valve so that the actual basis weight will proximate the desired basis weight.
Inventors
- 👤 Nallan C S Chari
- 👤 Andrew D Charos
- 👤 Harry D Walker Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:57
CPC Classifications
D; D21; D21G; D21G9/00; D21G9/0009; D21G9/0027; G; G01; G01G; G01G17/00; G01G17/02; G01G9/00; G01G9/005; Y; Y10; Y10S; Y10S162/00; Y10S162/06; Y10S162/09; Y10S162/10; Y10S162/11
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
192 words
The method of continuously controlling the basis weight of paper sheets or the like made by a machine of the character incorporating valve means for controlling the supply of papermaking stock to the machine comprising the steps of scanning a sheet of paper formed by the machine with a measuring device to develop an analog signal corresponding to the basis weight, converting the analog signal to an equivalent digital signal, comparing the digital signal with a reference representing the desired basis weight to determine a difference error, comparing the difference error with a certain error limit to establish a system gain factor, computing from the difference error, the system gain factor, and a predetermined system lag factor a timed position signal of a certain time duration and corresponding to the extent of movement and direction required of the valve means to alter the supply of stock to the machine, maneuvering the valve means in accordance with the position signal for the certain time duration to thereby cause the paper to be about the desired basis weight at the measuring device and repeating the cycle of steps immediately after the certain time duration.
Claim 2
Dependent Claim
32 words
The method as described in claim 2 wherein the computing step introduces an additional time delay factor determined by the grade of paper being made for accordingly altering the certain time duration.
Claim 3
Dependent Claim
36 words
The method as described in claim 2 wherein the step of comparing the digital signal with a reference includes determining the average of a plurality of measurements of the basis weight obtained during the scanning step.
Claim 4
Dependent Claim
85 words
The method as described in claim 2 wherein the step of comparing the digital signal includes determining the average of the measurements of the basis weight for the time of the scanning and determining the difference between the average of the basis weight measurements and the desired basis weight to establish the difference error, and wherein the method comprises the further step of comparing the difference error with a predetermined error limit to determine a system gain factor for incorporating in the timed position signal.
Claim 5
Dependent Claim
67 words
The method as described in claim 2 wherein the computing step includes determiniNg the required valve means movement and direction of movement from the previous valve means movement and direction and the predetermined system lag factor includes a certain valve means windup factor and also a certain backlash valve means factor determined by the direction of movement of the valve means relative to previous valve means movement.
Claim 6
Dependent Claim
70 words
The method as described in claim 5 wherein the computing step includes determining the required valve means movement and the direction of movement from the previous valve means movement and direction and the predetermined system lag factor includes a certain valve means windup factor and also a backlash valve means factor when the direction of the movement of the valve means is opposite that of the previous valve means movement.
Claim 7
Dependent Claim
24 words
The method as described in claim 2 further including the step of storing the position signal for use during the next cycle of control.
Claim 8
Independent Claim
222 words
The method of cyclically controlling the basis weight of paper sheets or the like made by a machine of the character incorporating valve means for controlling the supply of papermaking stock to the machine comprising the steps of measuring the basis weight of a sheet of paper formed by the machine by scanning the sheet and developing a series of analog signals corresponding to the instantaneous measured basis weight, converting the analog signals to equivalent digital signals, determining the difference between the average of the digital signals and a desired basis weight to establish a difference error, comparing the difference error with a certain error limit to establish a system gain factor, computing from the difference error, the previous position signal, a predetermined system lag factor and the gain factor a new timed position signal, of a certain time duration corresponding to the extent and direction of movement required of the valve means to alter the supply of stock to the machine, maneuvering the valve means in accordance with the position signal for the certain time duration so as to alter the supply of stock to the machine and thereby cause the paper to be about the desired basis weight, storing the new timed position for use in the next measuring cycle, and repeating the cycle immediately after the certain time duration.
Claim 9
Dependent Claim
204 words
In a control system for a papermaking machine, the combination of valve means controlling the supply of paper stock to the machine, means operating the valve means so as to vary the supply of paper stock in accordance with a position signal of a certain time duration, control means for developing position signals for application to the operating means so as to pulse the valve means for the certain time duration to vary the supply of paper stock, the control means including means sensing the actual basis weight of the paper and developing a corresponding analog signal, analog to digital converter means developing from the analog signal an equivalent digital signal, and computer means determining from the digital signal the difference between the actual basis weight and the desired basis weight comparing the difference between the actual basis weight and the desired basis weight with a predetermined error limit to establish a system gain factor, and developing for application to the valve operating means a position signal of the certain time duration and corresponding to the extent and direction of the valve means movement required to cause the actual basis weight to proximate the desired basis weight from the difference and system gain factor.
Claim 10
Dependent Claim
26 words
The control system as described in claim 10 wherein the sensing means includes a gamma gauge and scanner means moving the gamma gauge along the paper.
Claim 11
Dependent Claim
35 words
A control system as described in claim 10 wherein the computer means determines valve means windup and backlash factors determined by the direction of required movement to the valve means for determining the position signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-10 | 1975-07-12 | 1976-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-10 | 1979-07-12 | 1980-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-10 | 1983-07-12 | 1984-01-11 | $7700.00 | Window Closed / Lapsed |