| 摘要 |
<p>A machine for producing a web (46) of fibrous material (especially tissue or hygiene paper) has at least one pre-press (26) in the form of a shoe press, a main press (30) formed by a press roll (28) and a drying cylinder (60), an endless upper belt (12) which passes through the nips (48,90) of the pre-press and the main press, and an under-felt (50) which passes over a lower roll (38) of the pre-press. The product web (46), which is pre-formed in a former, is delivered by the upper belt (12) first to the pre-press and then to the main press. The pre-press (26), which is in the form of a shoe press having a press nip (48) which is elongated in the direction of web travel, comprises an upper shoe press unit (40) and an opposing roll (38), and the upper shoe press unit is provided with a smooth circulating flexible press belt (44). The lower roll (38) is grooved. The upper belt (12) is a relatively dense upper felt having a water permeability which is less than that of the lower felt (50), but the upper belt is capable of removing further water from the web in the main press (30) formed on the drying cylinder (60). The press roll (28) forming part of the main press (30) has a perforated and/or grooved surface to accept the water removed at this stage.</p> |
