A method to model web trajectory and release in forward roll coating

The trajectory of the web at the exit of a roll coating operation can influence the quality of the final coating. While methods to model the web trajectory have been given in the literature, these methods are limited in various ways. A method is proposed to describe the web trajectory and the pressure distribution in the fluid at the exit of a forward roll coater. The Reynolds lubrication equations for the fluid are coupled with the web by a force balance on web node points. The fluid pressure in the coating layer generates forces on the web. These forces deflect the web. Integration in time gives the web dynamics. The angle that the web is pulled from the nip and the tension are found to influence the pressure pulse in the divergent section of the nip to a large extent. Low tensions lead to a second pressure pulse followed by a sub-ambient or tack pressure. Pulling the web at various angles from the nip can cause the tack pressure to increase or decrease. Pressure pulses are predicted that are comparable to measurements by a laboratory device.