| 摘要 |
A dewatering press section for a paper or cardboard web includes a press roll having a wide pressing zone over which a belt is provided to run guided by guide rollers with the web being arranged to run in the pressing zone in compression between the press roll and the belt. At least one fabric runs in the pressing zone and acts on a respective face of the web. A pressure transmitting device has a surface which overlies the belt substantially in the pressing zone. According to the invention, ultrasonic field generators are provided in association with the pressure transmitting device surface for applying an ultrasonic field substantially in the pressing zone such that the friction between the surface of the pressure transmitting device and the belt is substantially reduced. The ultrasonic field generators can operate at a single frequency, at a plurality of discrete frequencies or may emit a continuous spectrum of frequencies and the intensity of the ultrasonic field is selected such that in addition to reducing the friction between the belt and the surface of the pressure transmitting device, the ultrasonic field will also substantially promote the removal of water from the web within the pressing zone as well as the transfer of water removed from the web into the press fabric or fabrics.
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