FI84572B - Process and device for regulating the transverse effect of wind dispersion in chipboard production - Google Patents

Description

84572

The present invention relates to a wind scattering step in particle board manufacturing, wherein the glued chips are sprinkled by dropping the chips into a flow of air directed substantially transversely to the flow of the chips. The chips fall under the influence of wind sorting onto the spreading platform. The platform travels at a speed commensurate with the chip flow and the desired blank thickness.

The problem with scattering is that, despite the equalization of the flows, the chips may settle on the scattering base in uneven amounts in its transverse direction, whereby a corresponding progressive groove is formed in the blank. The blank becomes wavy in the transverse direction. The formation of these wave formations can be reduced by influencing the 20-stroke air flow by providing an inverted band at the groove air flow at the groove formation. The turbulence in a given band results in the laminar flow surrounding the band tending to turn towards the turbulent region. The consequence of this reversal of the laminar flow is the additional number of chips it enters to fill the longitudinal groove.

Said strip-like eddy currents are provided for the spray-30 flow according to the prior art, so that the flow openings of the perforated plate compensating for the spray-air flow are locally constricted or closed. If the blowing system consists of pipes, a similar effect is obtained by restricting the flow of the optional pipe groups 35. However, this requires influencing the blowing system itself, which in turn affects the flows at other points as well. Choking also causes energy loss.

2,84572

The invention is based on the idea that the spray air flow is affected locally in a flow-limiting area between the flow equalization and the si-5 spray point. It is most preferred to act immediately before the point of sprinkling of the chips. The essential features of the invention appear from the appended claims.

The invention and the apparatus invented for carrying out the method according to it are described by means of the accompanying schematic drawing, in which

Figure 1 shows the apparatus 15 according to the invention seen from above

Figure 2 is a side view of the apparatus, and

Figure 3 shows the apparatus as seen from the wind chamber 20

The apparatus includes a fan 2, which provides the air flow required for wind chipping. The air flow is conducted through an expanding flow duct 3, at the mouth of which a flow equalizer is placed. This equalizer is usually a plate with a relatively dense perforation, or a similar member such as a wire mesh. After the flow equalizer there is a short flow chamber 8 for equalizing the air flow. After the flow chamber 8, there is an opening in the upper part of the apparatus extending beyond the transverse direction, from which the scattered, glued chips are led as smoothly as possible under the influence of the spray air flow. The chips and the air flows meet each other substantially perpendicularly, as a result of which a wind sorting of the chips extending into the wind chamber 6 is achieved. The chips thus sorted fall onto the sprinkler platform 1, which travels at a certain, steady speed.

3,84572

However, in spite of all the flow equalization measures, there are scattering situations in which one or some points of the particleboard blank in the transverse direction of the blank remain thinner than the surrounding areas. At such a point, a longitudinal deflection is formed in the blank. The formation of a groove or grooves can be prevented by directing more chips from the flowing chip stream under the influence of the wind to the groove point. The above-mentioned interference with the spray air flow at the outlet has proved to be a suitable control means.

According to the invention, it has been realized that, with the least disadvantages, this interference can be carried out after the scattering of the scattering air flow, i.e. approximately immediately before the scattering point of the chips.

In the exemplary apparatus shown in the accompanying drawing, this interference is performed by plates 7 arranged to be optionally inserted into the flow chamber 8.

The plates are narrow in relation to the width of the flow chamber 8, but correspond in length to the height of the chamber 8. The plates can be pushed independently into the chamber 8, at an optional height, and optionally withdrawn therefrom. 25 The plates are arranged over the entire cross-section of the wind chamber.

Instead of the closed plates 7 described, it is of course possible to fit corresponding air flow interfering elements in the apparatus, for example perforated or mesh plates.

Claims (8)

84572 A method for controlling the transverse amount of material in a chipboard blank 5 in chipboard production, wherein the spraying air flow is acted upon locally in a cross-sectional area of the flow in a flow-inhibiting manner, characterized in that the spraying air flow is affected between the flow equalization and the spraying point. Method according to Claim 1, characterized in that the spray air flow is influenced immediately before the spray point. 15 An apparatus for carrying out the method according to claim 1, which apparatus comprises a sprinkling base (1), a fan (2) for providing a sprinkling air flow, a flow-expanding sprinkling air duct (3), a flow equalizer (4) placed at the mouth of the duct, and a perforated plate, and devices for dropping the chip flow (5) into the wind chamber (6) transverse to the balanced air flow, characterized in that the apparatus comprises flow restrictors inserted between the flow equalizer (4) and the drop point of the chip flow (5) and inserted into the flow chamber (8) (7). Apparatus according to claim 3, characterized in that the flow restrictors are plates distributed over the transverse direction of the flow chamber (8), narrow with respect to the cross-sectional dimension of the flow chamber, substantially the length of the flow chamber and independently movable in the height direction of the apparatus. 35 Apparatus according to claim 4, characterized in that the plates have a width of about 5 to 500 mm, preferably 100 to 300 mm. Apparatus according to one of the preceding claims 3 to 5, characterized in that the flow restrictors 5 (7) are arranged 0 to 1000 mm before the drop point of the spreadable chip flow (5), preferably 0 to 500 mm before the drop point of the spreadable chip flow (5). 10 Patentkrav: