US3661701A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for controlling rush-drag in a paper machine
Assignee: Westvaco Corp
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Filing: 1970-06-23
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Granted: 1972-05-09
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Expires: 1990-06-23
Abstract
Abstract A system for controlling the difference between the velocity of a pulp slurry discharging from a paper machine headbox and the speed of the fourdrinier wire onto which said pump slurry is deposited. The system includes means for deriving a signal representative of the aforementioned speed differential thus allowing a direct comparison between the actual velocity differential and the desired velocity differential. The control system is based upon a differentiated and rearranged form of the equation v2 2gh which is dv (g/v)dh, wherein dv the rush or drag in units of speed, v the wire speed, g the gravitational constant, and dh the differential head, i.e., that part of the total head which gives rise to the velocity difference between the slice velocity and the wire speed, in units of inches of H20.
Inventors
- 👤 Abdul-Rahman A Al-Shaikh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 03:55
CPC Classifications
D; D21; D21G; D21G9/00; D21G9/0009; D21G9/0027; Y; Y10; Y10S; Y10S162/00; Y10S162/09; Y10S162/10; Y10S162/11
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
24 words
The system of claim 1 wherein said means for providing a speed signal provides a speed signal which is representative of desired wire speed.
Claim 2
Dependent Claim
22 words
The system of claim 1 wherein said means for providing a speed signal provides a speed representative of the desired slice velocity.
Claim 3
Dependent Claim
22 words
The system of claim 1 wherein said means for providing a speed signal provides a speed signal representative of actual wire speed.
Claim 4
Dependent Claim
43 words
The system of claim 4 wherein said means for controlling comprises: a. means for generating a control signal in response to said difference signal; and b. means for controlling the stock flow to the paper machine headbox in response to said control signal.
Claim 5
Dependent Claim
61 words
The system of claim 5 which comprises: a. means for providing a set point signal representative of the desired wire speed; b. means for comparing said set point signal with said signal representative of the actual wire speed to produce a wire speed difference signal; and c. means for controlling the wire speed in response to said wire speed difference signal.
Claim 6
Dependent Claim
23 words
The system of claim 6 wherein said means for controlling the stock flow comprises means for controlling the speed of the stock pump.
Claim 7
Dependent Claim
24 words
The system of claim 6 wherein said means for controlling the stock flow comprises means for controlling the bypass flow around the stock pump.
Claim 8
Dependent Claim
172 words
An improvement in the method of controlling the velocity of a slurry exiting from a paper machine headbox with respect to the speed of the wire on to which the slurry is deposited including the steps of obtaining a first signal representative of the total head in the headbox and obtaining a second signal representative of the actual wire speed, wherein the improvement comprises the steps of: a. obtaining a third signal representative of the square of the wire speed signal multiplied by a constant; b. comparing said third signal to said first signal to obtain a first difference signal; c. dividing said first difference signal by said second signal and multiplying by a constant to produce a fourth signal; d. obtaining a set point signal representative of the desired difference between the slice velocity and the actual wire speed; e. comparing said set point signal to said fourth signal to obtain a second difference signal; and f. controlling the stock flow to the headbox in response to said second difference signal.
References Cited (Backward Citations)
US3077924A
Cited
US3490689A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-09 | 1975-11-08 | 1976-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-09 | 1979-11-08 | 1980-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-09 | 1983-11-08 | 1984-05-09 | $7700.00 | Window Closed / Lapsed |