GB1378055A - Paper forming apparatus - Google Patents

Abstract

1378055 Paper-making apparatus BELOIT CORP 2 March 1972 [25 March 1971] 9891/72 Heading D2A Apparatus for forming a fibrous web comprises twin wires F1, F2 forming a nip N-1 for receiving stock from a headbox and extending over stationary guides 14, 16 and round a suction roll 20, the guides 14, 16 defining a curved path and the wire Fl being free from restraining means opposite the guides 14, 16 and the roll 20. The stock may be fed upwardly as shown or the apparatus may be inverted. The centre axis a of the headbox is substantially tangential to breast rolls 12, 13 and the stock contacts the wire F2 first, and the rolls 12, 13 may be adjustable to vary the nip N-1 and may be open or solid. The wires F1, F2 extend over tensioning guide rolls 19, 19' and are synchronously driven by drives M1, M2 at the speed of the jet of stock leaving the headbox, and they are made of bronze, steel, copper, plastics or fabric strands. The guide 14 includes spaced transversely extending members having wire-contacting edges 15a of wear-resistant material such as ceramics or plastics, and the guide is subject to vacuum. The guide 16. is a vacuum box and has a wire-contacting surface which may be flat but is preferably curved with a radius of curvature less than that of the guide 14. A doctor 17 engages the wire F1 and directs removed water to a saveall Sa. More than one doctor 17 and further guides 16 may be provided. Members 18 prevent fluttering of the wires Fl, F2 and pressurized air is supplied at 18a to facilitate adherance of the web to the wire F2. The vacuum in the guide 16 is greater than that in the guide 14 and less than that in the roll 20 which has compartments 19, 21, 22 subject to respectively increasing amounts of vacuum. A doctor 17a engages the wire F2 and the breast and guide rolls for the wires F1, F2 also have doctors. The web is transferred to a pick-up felt PF and travels with the felt through a roll press nip WN-1, and a felt only roll-press nip FN-1 is also provided. The press rolls 25, 26, 27 may be plain, blind-drilled, suction or grooved rolls. In an alternative embodiment, Fig. 2 (not shown), the guide 14 has a smooth water-impermeable surface, a curved leading edge and an abruptly diverging trailing edge.