Adjustable paper machine headbox with adjustment sensing means

Paper making and fiber liberation – Apparatus – Electric controls or systems

Patent

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Details

33147L, 33147N, 33174PA, 33174PB, 162259, 162263, 162347, D21F 102

Patent

active

043426190

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to paper machine headboxes. More particularly the invention relates to a headbox of the type in which a slice opening running the full width of the headbox for discharging pulp stock is formed by a bottom slice lip, and a rigid top slice lip which can be raised or lowered over the full width of the headbox, said top slice lip being provided with a bendable profile bar running the full width of the headbox, said profile bar limiting a pulp stock discharge nozzle in the vertical direction and being locally displaceable in the vertical direction by means of a plurality of adjusting assemblies distributed along the top slice lip in order to allow local adjustments of the height of the pulp stock discharge nozzle.


BACKGROUND ART

In paper machine headboxes of the present type, the profile bar on the top slice lip serves to "modulate" the flow of the pulp stock through the horizontal slice opening in the transverse direction, i.e. to allow a control of the grammage of the paper in the transverse direction of the paper web. The adjustment of the profile bar relative to the top slice lip is carried out by means of adjusting knobs or the like, which can be reached by an operator from a bridge that transverses the paper making machine. In connection with these adjusting knobs or corresponding means there are provided reading instruments showing the recorded position of the profile bar. However, due to unavoidable play in the transmission between the profile bar and the reading instruments, the indication is unsafe wherefore the recorded position can deviate from the real position of the profile bar. The deviation often is greater than can be tolerated.


DISCLOSURE OF THE INVENTION

At the headbox of the present invention, the indication can be performed with a very high accuracy. In fact, the present invention is characterized in that each adjustment assembly comprises an electrical level sensor with two members which are movable relative to each other, one member being mechanically connected to the profile bar without play, while the second member is mechanically connected to the top slice lip without play, said level sensor being electrically connected with an indicator.
By this system which readily can be installed also for already existing headboxes, any influence upon the indication from play in the mechanical transmission between the profile bar and the adjusting knobs or corresponding means is eliminated. The indicator of course can be individual for each level sensor but preferably it is joint for all level sensors. In the latter case it is provided with a selector by means of which one level sensor at a time may be selected for indication. The indication equipment advantageously may be completed with a selector device which automatically selects all level sensors in their proper turns, and with a recorder or other registering instrument which registers the measurement result received from each level sensor. The level sensors provided according to the invention of course can be integrated in a regulation system which automatically provides for a proper adjustment of the profile bar.


BRIEF DESCRIPTION OF DRAWINGS

An embodiment of the invention will now be explained with reference to the accompanying drawings in which:
FIG. 1 schematically shows a section through the slice of a headbox provided according to the invention, and
FIG. 2 shows more in detail a section through a profile bar and adjacent portions of a top slice lip.


BEST MODE OF CARRYING OUT THE INVENTION

The headbox slice of the headbox, shown in FIG. 1 comprises a fixed bottom slice lip 11 and a top slice lip 12 which is mounted above the bottom slice lip 11 and provided so that it can be raised or lowered. The two slice lips 11 and 12 run the full width of the paper machine headbox and define between them an horizontal slice opening 13 for discharging the diluted pulp stock. The pulp stock is supplied to the portion of the headbox which is not shown in FIG. 1, said headbox being exerted to an overpr

REFERENCES:
patent: 2022298 (1935-11-01), Neilson
patent: 2779253 (1957-01-01), Owens
patent: 3463701 (1969-08-01), Curtis
patent: 3976539 (1976-08-01), Kirgavainen
patent: 3994773 (1976-11-01), Wolf et al.
Macdonald, Editor; Pulp and Paper Manufacture, 2nd Edition, vol. III; McGraw-Hill, (N.Y.), 1970, pp. 271-272.

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