Paper making and fiber liberation – Processes and products – With measuring – inspecting and/or testing
Patent
1992-02-28
1994-03-29
Jones, W. Gary
Paper making and fiber liberation
Processes and products
With measuring, inspecting and/or testing
162253, 162263, 162204, 34 49, 34 68, D21F 706
Patent
active
052981215
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the manufacture of paper. Paper manufactured in strip form should be of uniform thickness and it is also desirable that the paper has uniform stretch characteristics. This means that, when longitudinal tension is applied to the strip of paper, it should stretch uniformly at all positions across its width.
In the use of the strip of paper subsequent to its manufacture, it is almost invariably necessary to apply longitudinal tension to the strip of paper. If the paper does not stretch uniformly across its width, the tension at some regions across the width of the strip will be greater than at other regions and the applied tension will have to be kept at a level which does not cause the paper to tear at the regions of highest tension. This is particularly true if the, or one of the, regions of highest tension is at one edge of the strip of paper. Consequently, the operating machinery which applied longitudinal tension to the strip of paper has to be operated at a speed which is less than would be the case if the stretch were uniform across its width.
Furthermore, in a multi-colour printing press, if the paper does not stretch uniformly across its width, the various colored inks applied to the paper will not be correctly positioned and the printing will be of unsatisfactory quality.
It is an object of the present invention to provide a method of controlling the axial stretch property of a strip of paper during its manufacture.
According to the present invention, in a method of operating a paper making machine to control the axial stretch property of a strip of paper manufactured in the machine, the strip of paper moving in the direction of its length and under axial tension is caused to pass around part of the periphery of a rotary device extending across the width of the paper and substantially normal to the direction of movement thereof, said device comprising a plurality of rotatable bodies arranged side-by-side and each body having means associated with it for producing a signal representing the tension in the longitudinally extending portion of the strip which contacts the body; a thickness measuring gauge is arranged to provide signals representing the effective thickness of said portions of the strip which contact the bodies; said signals are employed to produce control signals representing the load per unit of cross-sectional area of said portions of the strip; and the control signals are employed to control the operation of the paper making machine to keep said control signals substantially constant across the width of the strip.
The control signals may be used to control the moisture of the strip, or the drying rate, or the gap between various rollers of the calender in the paper making machine. The control signals may also be used to adjust the cross flow in the header or the mixing of the paper fibers in the header box as the water/paper slurry is placed on the wire mesh.
In order that the invention may be more readily understood, it will now be described, by way of example only, with reference to the accompanying drawings, in which:
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 shows diagrammatically a strip of paper leaving a paper making machine; and
FIG. 2 shows diagrammatically a paper making machine.
In FIG. 1, a conventional paper making machine is indicated generally by the reference numeral 1. The outlet of the machine is indicated by a pair of calender rollers 3. Downstream of the calender rollers, and extending transverse to the paper strip 5 leaving the paper making machine, is a rotary device 7 consisting of a plurality of cylindrical rotatable bodies 9 arranged side-by-side and rotatable about an axis 10. Each cylindrical body has means (not shown) associated with it for producing an electrical signal which represents the force applied to the periphery of the body by the part of the strip 5 which bears against it when the strip, under tension, passes over the rotary device. These signals are supplied to a control device 11. Also provided adjacent the rotary device
REFERENCES:
patent: 3622448 (1971-11-01), Adams et al.
patent: 3801426 (1974-04-01), Putman et al.
patent: 4098641 (1978-07-01), Casey et al.
patent: 4157039 (1979-06-01), Kilmister et al.
patent: 4188731 (1980-02-01), Rauskolb
patent: 4712472 (1987-12-01), Meisen et al.
"Computer Control of a Combination Paperboard Machine" by Dudley E. King, Jr. Tappi, Aug. 1976, vol. 59, No. 8 pp. 52-55.
Davy McKee (Poole) Limited
Jones W. Gary
Nguyen Dean T.
LandOfFree
Method of controlling the axial stretch property of a strip of p does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of controlling the axial stretch property of a strip of p, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of controlling the axial stretch property of a strip of p will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-789047