Back to results
US 4,209,360 AGranted
Two-sided drainage in a roll-type twin-wire former
AssigneeAB Karlstads Mekaniska Werkstad
InventorsErik G. Stenberg, Douglas Wahren, Carl Zotterman
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeAB Karlstads Mekaniska Werkstad
InventorsErik G. Stenberg, Douglas Wahren, Carl Zotterman
Estimating the term…
Methods and apparatus for producing a web by injecting a jet of stock between two tensioned wires and running the wires over a circumferentially grooved forming cylinder. The cylinder grooves and a zone immediately on the other side of the wires extending from the forming throat where the web is injected to the web run-off point are in direct, open communication with the ambient atmosphere so that water is drained inwardly and outwardly of the forming cylinder as the web is being formed. The jet stock size, wire speed and wire tension are adjusted in relation to the radius of the forming cylinder so that the inward and outward drainage of liquid from the web occurs in relative amounts sufficient to avoid substantial two-sidedness of the web thus produced.
In a method of producing a web from a jet of stock injected between a pair of tensioned forming wires run around a peripheral segment of a forming cylinder having multiple circumferential grooves formed in the periphery thereof, the improvement comprising the steps of maintaining the cylinder grooves and a zone outside said wires and adjoining said peripheral segment in open, direct communication with the ambient atmosphere such that part of the liquid in the web drains outwardly as the wires run over said peripheral segment, and part is pressed inwardly into said cylindrical grooves with displacement of the air therein into the ambient atmosphere and is expelled from the grooves as the wires leave the forming cylinder, solely in response to forces resulting from translation and compression of the web by the forming wires as they are run around said peripheral segment, and adjusting the wire speed and tension, and the thickness of the injected jet in relation to the radius of the forming cylinder to achieve a ratio of inwardly drained liquid to outwardly drained liquid that will result in the production of a web without pronounced two-sidedness.
In apparatus for forming a web comprising a rotatable forming cylinder having multiple circumferential grooves formed in the periphery thereof, a pair of endless forming wires, means for supporting said wires so that they converge to form a forming throat substantially tangential to the surface of the forming cylinder and thereafter run together over a segment of the surface of the forming cylinder to a run-off point where they leave the cylinder together, means for adjusting the tension in the wires, headbox means for injecting a jet of stock into the forming throat to be pressed between said wires to form a web therebetween with the discharge of liquid inwardly and outwardly of the forming cylinder, and save-all pan means positioned to collect liquid discharged outwardly, the improvement comprising means providing open, direct communication between the ambient atmosphere and the cylinder grooves contained in said cylinder segment, the adjoining space on the opposite side of the web and said save-all pan means such that part of the liquid in the web drains outwardly as the wires run over said peripheral segment and part is pressed inwardly into said cylindrical grooves with displacement of the air into the ambient atmosphere and is expelled from the grooves as the wires leave the forming cylinder, solely in response to forces resulting from translation and compression of the web by the forming wires as they are run around said cylinder segment, the grooves having sufficient volume to receive inwardly discharged liquid drained from the web with displacement of any air contained in the grooves, and to store such liquid until the wires with the web therebetween leave the forming cylinder at the run-off point where the stored liquid is expelled from the grooves, the forming cylinder having a radius such that for specified values of jet stock size, wire speed and wire tension, liquid drainage from the web inwardly and outwardly of the forming cylinder will be in relative amounts sufficient to avoid substantial two-sidedness in the web thus produced.
Dependencies are inferred from the claim text.