GB1419386A - Press for travelling webs - Google Patents

Abstract

1419386 Drying webs BELOIT CORP 12 Dec 1972 [20 Dec 1971 1 March 1972 6 April 1972] 57344/72 Heading F4G Paper web W and felt F pass through a press comprising a first region throughout which the pressure increases at a rate that avoids crushing the web, a second region in which the pressure is uniform and a third region in which the pressure decreases rapidly to prevent water reentering the web from the felt. In Fig. 2 the web is pressed against the roll 10 first by belt 11, then by belts 11 and 12 together and then by belts 11, 12 and 13 combined as it moves round the roll giving a stepwise increase in pressure. The magnitude of each pressure and the duration of its application are varied by moving the rollers 20, 22, 24 and 21, 23, 25. To prevent roll 10 from being distorted by the pressures its surface may be supported from inside by a body of liquid or by a shoe pressed against its inside surface by a piston. In Figs. 4 and 5 the web W and felt F are pressed between impervious belts 110, 111. The pressure, applied by bearing members 119, 120 gradually increases between converging surfaces 123, 124, is uniform between chambers 121, 122 where it is applied by pressurized fluid inside the chambers, and decreases rapidly between diverging surfaces 125, 126. The pressure applied between surfaces 123, 124 and 125, 126 is varied by altering the distance between opposing surfaces. In Fig. 9 the pressure is increased stepwise between pairs of opposing pressure chambers, 22-225. Fluid is supplied to a typical chamber 220 via a corresponding control valve 230 and a chamber 226 which has flexible side walls 227, 228 to prevent the applied pressure being affected by bending of the supporting beam 218. The chambers may be arranged around a cylinder. The lower belt 211 may be omitted. Pressure may be applied to only one side of the web.