Boundary air layer modification structure for heat transfer roll

Abstract

The invention relates to a simple mechanical system to effect removal, reduction or change in composition of boundary layered atmosphere associated with web passage around a heat transfer roll. In effect, the purpose of the invention is to eliminate the layer of air between the web and the heat transfer roll, or to eliminate as much air as possible so that better and more intimate contact is achieved between the web and the heat transfer roll, or to change the pressure and composition of the atmosphere, thus assuring higher efficiency of heat transfer from the roll to the web. The mechanical structure can involve a squeeze roll positioned between the heat transfer roll, squeezing the boundary layer of air attached to the web out prior to web contact to the heat transfer roll. In addition, the squeeze roll could utilize some type of vacuum associated with it. The invention further contemplates reducing the temperature of the boundary layer of air by cooling it and by utilizing stationary boundary layer removal bars and/or squeeze rolls. A squeeze roll is preferably of rubber or plastic with a softer surface so that it makes intimate contact with the heat transfer roll and is driven by contact therewith.

Dependencies are inferred from the claim text.