| 摘要 |
993, 837. Paper making machines. PULP & PAPER RESEARCH INSTITUTE OF CANADA. April 27, 1964 [April 29, 1963], No. 17410/64. Heading D2A. A paper-making machine comprises means for introducing paper stock between two foraminous belts which travel together over foraminous cylindrical surfaces in first second and third zones in which water is extracted from the paper web. A head box 11 discharges paper stock into the nip between foraminous belts 24, 30 which travel together around parts of the surfaces of perforated rolls 13,15,17, roll 15 being provided with a pressure box 8 supplied with air at up to half an atmosphere superatmospheric pressure and roll 17 having a suction box 9 which applies suction to the web at a greater pressure differential than is applied by pressure box 8. In the first zone of water extraction, i.e. where the web and belts pass around the roll 13, water is expelled both outwardly into trough 47 and inwardly into the holes 48 in the cylinder 13 from which it is subsequently thrown by centrifugal force into trough 49. In modifications, the first roll 13 may be provided with a suction or pressure box (Fig. 4, not shown) and the pressure and suction boxes of the second and third rolls may be subdivided with a plurality of pressure and suction compartments in which graduated pressure or suction may be applied to the web (Figs. 5 and 6 not shown). In a further embodiment of the invention (Fig. 7 not shown), the second and third zones comprise different parts of the surface of a single foraminous roll while in a still further embodiment (Fig. 8 not shown) the first and third zones comprise separate parts of a single foraminous roll. Specification 903, 161 is referred to. |
