| 摘要 |
The invention relates to a simple mechanical system, by means of which the composition of the boundary-layer atmosphere connected to the passage of a web around a heat-transmission roller is removed, reduced or varied. The aim of the invention is to eliminate the air layer between the web and the heat-transmission roller or to remove as much air as possible, so that more intimate contact is achieved between the web and the heat-transmission roller, or to vary the pressure and the composition of the atmosphere to the effect that a higher efficiency of the heat transmission from the roller to the web is achieved. For this, the mechanical structure can have a squeezing-off roller which is located between the heat-transmission roller and by which the air boundary layer adhering to the web is stripped off before the contact of the web with the heat-transmission roller. At the same time, a vacuum can also be applied at the squeezing-off roller. Furthermore, the object of the invention is to reduce the temperature of the air boundary layer by cooling the latter and by using fixed boundary-layer air removal rods and/or squeezing-off or stripping-off rollers. The squeezing-off roller is covered with a soft surface, preferably of rubber or a plastic, so that it comes into intimate contact with the heat-transmission roller and is driven as a result of this contact.
|
