Paper-making machine headbox with partial partitions

Details Paper-making machine headbox with partial partitions Paper-making machine headbox with partial partitions

1997-03-24

1999-11-16

Hastings, Karen M.

Paper making and fiber liberation

Apparatus

Running or indefinite length product forming and/or treating...

162258, D21F 102

Patent

active

059850990

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to the field of paper-making, and more particularly to the field of producing a sheet of paper continuously from fiber pulp diluted in an aqueous medium also incorporating presently-known additives.
In the above field, it is normal practice to provide the fiber solution in a compartment called a headbox whose function is to feed a nozzle opening out through two close-together lips above a conveyor belt whose first function is to drain the solution to start the sheet-forming process and whose second function is to convey the sheet to successive units that together constitute a machine for producing paper continuously.
Such technology is widely known, as are the requirements specific to a headbox which can be fed by means of a back distributor communicating with the headbox proper via a perforated backplate.
It is considered necessary to generate turbulence in the fiber solution in order to maintain good uniformity and good distribution prior to equalizing the solution upstream from the nozzle for applying and spreading it on the conveyor belt.
In such a feed system, it has been observed that currents or streams become established causing fibers to be concentrated in certain zones to such an extent that the resulting sheet cannot be considered as being homogeneous. Uncontrollable local changes in fiber orientation have also been observed which likewise give rise to non-homogeneous finished products.
In general, it is therefore desirable to be able to control fiber concentration and orientation.


PRIOR ART

That is why proposals have been made to implement apparatuses that are still in service and that consist in enabling at least one of the lips of the nozzle to be deformed in such a manner as to modulate the flow section so as to favor certain application and spreading zones in consideration of the distribution width of the nozzle.
That constitutes some kind of adjustment means acting downstream from the headbox, "downstream" being considered relative to the flow direction through the headbox from feed inlet to application and spreading.
Such means make it possible to regulate the density of the applied pulp, but it is then observed that favored fiber orientations appear. Such means therefore do not enable both parameters to be controlled.
In an attempt to improve the operation of a headbox and to eliminate or reduce the negative effects of the control that may be provided by means of the deformable lips of the nozzle, another technology has been recommended.
That technology causes the headbox to be fed from an installation that delivers an aqueous solution which is conveyed by means of feed tubes or pipes at the back of the headbox where said tubes or pipes are connected to connection pieces extending parallel to one another.
That technique makes it possible to improve control over local feed compared with a conventional distributor, but it does not suffice to provide a solution to the problem posed.
Improvements have been made to such a technique by proposing to partition the reception chamber of the headbox to define internal channels each corresponding to a respective feed tube. That is the teaching given by application WO 88/01318. It would appear that that disposition has not provided all of the looked-for improvements.
Proposals have subsequently been made to associate the various back feed-tubes with dilution adjustment blocks including respective adjustable valves for the tubes making it possible to adjust the specific dilution of the solution delivered by each tube by adding aqueous medium independently. By way of example, such a proposal is taught by application DE 4 019 593.
That technique was expected to make upstream adjustment of the headbox possible to achieve control over the sheet as applied and spread, thereby controlling and adjusting density in the cross direction more effectively, to obtain a product that is uniform.
That technology has indeed provided improvements, but it would appear that it does not enable the problem posed to be compl

REFERENCES:
patent: 3216892 (1965-11-01), Wahlstrom
patent: 4406741 (1983-09-01), Kirjavaninen
patent: 4534399 (1985-08-01), Steen
patent: 4980027 (1990-12-01), Keller
patent: 5304285 (1994-04-01), Meinecke et al.
patent: 5549792 (1996-08-01), Begemann et al.
patent: 5626178 (1997-05-01), Merath
patent: 5695611 (1997-12-01), Bubik et al.
patent: 5707495 (1998-01-01), Heinzmann et al.

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