Claims
- 1. A method of controlling a cross profile of properties of a paper web across a feed direction thereof in a paper machine, wherein said cross profile can be affected by several setting positions across the web in such a manner that a definite change in a setting position brings about a corresponding response in said cross profile, said response extending in a lateral direction beyond that web portion which corresponds to the web width of the setting, said method comprising the steps of:
- measuring an actual cross profile and comparing with a desired cross profile;
- indicating a deviation between the measured cross profile and the desired cross profile in the form of a first error cross profile;
- comparing each of the responses from the setting positions by turn with the first error cross profile for determining necessary mutual relative change in each setting position by multiplying the first error profile with the response locally about each setting position and summing up the result;
- calculating the corresponding necessary relative change in the cross profile from said determined necessary relative change in each setting position by means of the responses;
- determining an amplifying factor (k) by minimizing the difference between the desired cross profile and the measured cross profile added to the result of k multiplied with the necessary relative cross profile change;
- calculating necessary absolute change in each setting position as k corresponding relative change;
- determining the resulting change in cross profile by means of the responses;
- adding said determined change in cross profile to the measured cross profile and comparing with the desired cross profile to determine a deviation which constitutes a second error cross profile;
- repeating the method with said second error cross profile if the deviation is greater than a predetermined degree; and
- utilizing the calculated necessary absolute change in each setting position for adjustment in the setting positions.
- 2. The method as defined in claim 1 wherein the paper web is formed by outflow of a stock through a nozzle, and the flow through the nozzle is controlled in each setting position.
- 3. The method as defined in claim 1 wherein the paper web is formed on a wire, whereafter it is affected in setting positions along the web where free surface water is still visible on the web.
- 4. The method as defined in claim 1 wherein the paper web is formed, in that a stock flows out onto a wire through a nozzle and the web is affected in setting positions both in the nozzle and along the web.
- 5. The method as defined in claim 4 wherein the cross profile of the properties is divided into two components by low-pass (LP) and high-pass (HP) filtrations, in such a manner, that the setting positions in the nozzle control on the LP part, and the setting positions along the web control on the HP part.
- 6. The method as defined in claim 4 wherein the cross profile of properties is controlled by alternatingly making changes in the setting positions in the nozzle and in the setting positions along the web.
- 7. The method as defined in claim 1 in that consideration is made to different properties of the paper web, in that the first error profile is calculated as a weighted error profile by multiplication with a profile of weights which determines the weights to be attached to the different properties across the web direction.
- 8. The method as defined in claim 1 wherein the paper web is formed by outflow of a stock through a nozzle and the flow is controlled by movement of an upper lip of the nozzle in the different setting positions, and that the position of the upper lip is indicated and weighted together with the different properties of the paper web for resricting the deflection of the upper lip.
- 9. The method as defined in claim 1 in that different weights are attributed to the different setting positions, in that the calculated change in each setting position is multiplied by a factor of weights, before the calculation is continued.
Priority Claims (1)
Number |
Date |
Country |
Kind |
8004084 |
Jun 1980 |
SEX |
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Parent Case Info
This is a continuation, of application Ser. No. 438,573 filed 11/01/82, now abandoned, which is a continuation of application Ser. No. 264,838, filed on 05/18/81, now abandoned.
US Referenced Citations (4)
Foreign Referenced Citations (1)
Number |
Date |
Country |
2025088 |
Jan 1980 |
GBX |
Continuations (2)
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Number |
Date |
Country |
Parent |
438573 |
Nov 1982 |
|
Parent |
264838 |
May 1981 |
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