The Dynaflo concept is the result of extensive researches carried out since the late '70's on OVER's pilot plant. The flow coming from the computer designed tapered header is passes through a first perforated plate into a mixing/equalizing chamber that optimize the stock pressure and fiber sospention just before the turbolence generator. The turbolence generator is core of the DYNAFLO concept: the stainless steel Dynaflo tubes, which present a conical cross section, transitioning gradually from round to rectangular.
After a high acceleration at the inlet orifice, a gradual diffusion of the stock flow along the Dynaflo tubes weakens the large scale turbulence, while sustaining small-scale turbulence, thanks to the many boundary layers generated by the friction with the tube walls. Each tubes row has an optimum velocity range: by multiplying the tubes row, a broad range of flow rates can be accommodated, giving this headbox design a great adaptability to all operating conditions. The configuration of the tubes row ensures a negligible residual wake signature on the stock jet. This concept, after 30 years from its birth, still gives one of the best sheet formation made on today's hydraulic headboxes.
DYNAFLO-FL: HEADBOX WITH LAMELLAS
The headbox can be supplied with stiff lamellas in the slice area in the model DYNAFLOW-FL. The lamellas maintain high the level of micro-turbolence up to the jet exit, improving the paper formation at high speed. Special lamellas' tip design is performed to avoid the wake effect in the slice flow.
DYNAFLO-FL is available also in a multilayer layout. The multilayer headbox permits the use of two/three different stock characteristics/quality to produce multilayer paper with one forming section.
The edge flow control is another important optional for this headbox. A special designed system capable to modify locally the flow (on the edges of the heabox) from 60% up to 160% of the nominal flow, thus permitting optimal fiber orientation on the entire paper width.
The Dynaflow construction is entirely in solid stainless steel, with thorough finish and electropolishing of all the surfaces in contact with the stock, will guarantee a safe and trouble-free operation for many years.
The different available sizes of the Dynaflo-F cover a range from 2 to 18 m3/m.