Headboxes

The Over Concept is applied for the production of linerboard,
corrugating medium, writing & printing paper, newsprint, as well as tissue. 

 

"over concept" headboxAn excellent stock dispersion is guaranteed by the step turbulence-generating device at the basis of this hydraulic headbox, developed and manufactured in OVER's last years. The flow coming from the computer designed tapered header passes through a first perforated plate, with DC dilution control, and then into a mixing/equalizing chamber that optimizes the stock pressure and fiber suspension just before the turbulence generator, which applies a “STEP” concept: the stainless steel STEP tubes present a step cross section, transitioning gradually from round to rectangular.

 

"over concept" headboxAfter a high acceleration at the inlet orifice, a gradual diffusion and deceleration of the stock flow along the STEP tubes generates the turbulence necessary for the optimal fiber distribution. Each tubes row has an optimum velocity range: by multiplying the tubes row, a great range of flow rates can be accommodated, giving this headbox design the greatest adaptability to all operating conditions.
The OVER CONCEPT headbox is supplied with lamellas in the slice area, which maintain high the level of micro-turbulence up to the jet exit improving paper formation at high speeds. Special lamellas' tip design is performed to avoid wake effect in the slice flow. It's available also in a multilayer layout, which enables the use of two or three different stock characteristics and quality to produce multilayer paper with one forming section.

 

The edge flow control is another important optional for this headbox, indeed a special system is designed to modify locally the flow on the edges of the headbox, from 60% up to 160% of the nominal flow, thus permitting optimal fibre distribution on the entire paper width. Its entire construction in solid 316 L stainless steel, with thorough finish and electropolishing of all the surfaces in contact with the stock, guarantees 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.