ABSTRACT
The break can often be traced back to violent vibra tions of the paper edges.
The felt rollers are sometimes relocated such that the felts can give partial support to the paper span. However, in the wedge-shaped spaces near rollers, positive or negative pressures are developed due to the velocity of the webs and the rollers, causing the paper to separate from the felt. To reduce the sepa ration, blow boxes, with slots along the full width of the web, blow drying air against the paper. Excess air departs through the sides of the machine, leading to a cross-machine direction (CMD) air flow. Figure 2 is a simplified view of a moving web subjected to air flowing towards the edges. In real-world situa tions, the air flow is not uniform and the flow field is three-dimensional.
