Textiles: fiber preparation – Assembling – Web forming
Reexamination Certificate
2000-09-19
2001-08-28
Calvert, John J. (Department: 3765)
Textiles: fiber preparation
Assembling
Web forming
C019S296000, C019S304000
Reexamination Certificate
active
06279201
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device for separating particles, preferably wood fibers dispersed in a carrier gas, from a distribution means for distributing the particles on a running web, such as in the manufacture of wood fiberboard.
BACKGROUND OF THE INVENTION
In forming stations for the manufacture of wood fiberboard there is a demand for distributing glue-coated wood fibers onto a wire or belt to form a layer of a certain definite thickness. The layer of wood fibers is transported by the wire or belt to a press installation, in which the wood fibers by the effect of pressure and temperature are pressed into the form of a coherent board.
A device of this kind is described in Swedish Patent No. 457,729, the object of which is to provide a material web having a uniform material distribution. This is achieved by a carrier gas containing wood fibers being supplied tangentially to a convex surface, where fine grained fibers, by the action of the so-called Coanda-effect follow along with the carrier gas along the convex surface to a first outlet, which opens to an endless permeable web, while coarse grained fibers and lumps follow a substantially straight path to a second outlet, which is connected to a line for re-circulation of the fibers. In connection with the endless web there is provided a suction box for collecting and recycling the carrier gas. Although this arrangement has operated satisfactorily, it was found at certain applications that the carrier gas has caused eddy formation, with non-uniform material distribution as a result thereof.
The present invention has an object of separating the particles from the carrier gas and producing a homogenous layer with uniform distribution of particles across the width of the material web.
SUMMARY OF THE INVENTION
In accordance with the present invention, this and other objects have now been realized by the invention of apparatus for separating particles dispersed in a carrier gas being delivered from a distributor to a moving web, the apparatus comprising a rotatable roll, supply means for supplying the particles dispersed in the carrier gas substantially tangentially to the rotatable roll at a first predetermined speed, means for rotating the rotatable roll at a second predetermined speed, the second predetermined speed being substantially greater than the first predetermined speed whereby the particles are separated from the carrier gas, the rotatable roll including a discharge opening for discharging the particles towards the moving web, and a return line for recycling the carrier gas. Preferably, the particles comprise wood fibers, and most preferably the moving web is adapted for the manufacture of wood fiberboard.
In accordance with one embodiment of the apparatus of the present invention, the discharge opening is adapted to open freely to a space directed towards the moving web. In a preferred embodiment, the supply means and the return line partially enclose the rotatable roll, and the apparatus includes a partition wall for substantially providing a seal between the supply means and the return line at an upper portion of the rotatable roll. Preferably, the supply means includes a lower edge and the return line includes a lower edge, and the discharge opening is defined by the lower edges of the supply means and the return line.
In accordance with one embodiment of the apparatus of the present invention, the second predetermined speed is from about two to ten times the first predetermined speed. More preferably, the second predetermined speed is from about five to eight times the first predetermined speed.
In accordance with another embodiment of the apparatus of the present invention, the return line includes an opening, and the return line is disposed directly adjacent to the rotatable roll and the opening substantially upstream of the rotatable roll.
In accordance with the present invention, a method has also been devised for separating particles dispersed in a carrier gas being delivered from a distributor to a moving web, the method comprising rotating a rotatable roll, supplying the particles dispersed in the carrier gas substantially tangentially to the rotatable roll at a first predetermined speed, the rotatable roll rotating at a second predetermined speed, the second predetermined speed being substantially greater than the first predetermined speed whereby the particles are separated from the carrier gas, discharging the particles from the rotatable roll to a discharge opening, and recycling the carrier gas. Preferably, the particles comprise wood fibers, and most preferably, the moving web is adapted for the manufacture of wood fiberboard.
In accordance with one embodiment of the method of the present invention, the method includes discharging the particles freely into a space towards the moving web.
In accordance with another embodiment of the method of the present invention, the second predetermined speed is from about two to ten times the first predetermined speed, and more preferably, from about five to eight time the first predetermined speed.
The objects of the present invention are achieved by a device of the kind described above, in which the carrier gas and particles are separated from each other in view of the fact that said roll rotates at a speed which substantially exceeds the speed of the supplied carrier gas, the particles are discharged through an outlet, and the carrier gas is recycled through a return line.
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patent: 4489462 (1984-12-01), Dodson, Jr.
patent: 4712277 (1987-12-01), Gustavsson
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patent: 5205018 (1993-04-01), Leifeld et al.
patent: 5303455 (1994-04-01), Leifeld
patent: 5737806 (1998-04-01), Leifeld et al.
Johansson Lars-Erik
Jonasson Stellan
Salo Heikki
Calvert John J.
Lerner David Littenberg Krumholz & Mentlik LLP
Valmet Fibertech AB
Welch Gary L.
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