Drying and gas or vapor contact with solids – Apparatus – With fluid current conveying of treated material
Patent
1998-11-19
2000-08-29
Gravini, Stephen
Drying and gas or vapor contact with solids
Apparatus
With fluid current conveying of treated material
34638, 34639, 34641, 34656, F26B 1700
Patent
active
061089397
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a blower nozzle for heating and cooling web-like materials.
Blower nozzles of this type are used, for example, for heating or cooling web-like materials, in particular in the production of plastic foil. In this case, the blower nozzle is arranged transversely, i.e. generally perpendicularly, to the take-off direction of the material web, and thus transversely to the web running direction, above and/or below the material web.
It is particularly important for the foil process that the outflow from the nozzles is even, since uneven heating of the plastic foil during processing can have negative effects on the thickness profile. This is because slightly warmer regions are stretched more and are thus thinner than relatively colder plastic foil regions, which then obtain a somewhat thicker foil cross section. Uneven heating or cooling of the foil also leads, however, to a deterioration in the flatness of the final product.
Even blowing is particularly crucial for the production of ultrathin films or foil whose thickness can be reduced down to about 0.4 .mu.m.
Various proposals have already been made to even out the outflow speed for heating or cooling continuous webs of material, in particular plastic foil webs. EP-A1-0 377 311 proposes a blower nozzle having two supply chambers which are seated next to one another, extend transversely to the take-off direction of the material web, are provided, in each case opposite one another, with a supply aperture for the hot gas of the hot air, and are closed at their respective, opposite end. The cross section of the respective supply chamber decreases in a web-shaped manner from the supply aperture to the opposite, closed end parallel, in the side view, to the take-off direction of the plastic foil web. A distribution chamber is then seated below the two supply chambers arranged next to one another, with the result that the opposite hot gas flowing in at the end side via the supply chambers can then pass via overflow apertures, arranged between the two supply chambers and the distribution chamber, essentially transversely to the plane of the material web into the distribution chamber and from there can emerge in a transverse direction transversely to the plastic foil web via outlet apertures situated at the bottom.
Since two supply chambers which are symmetrically opposite to the central longitudinal direction of the plastic foil web are thus provided, it is possible for an equal distribution of pressure to be obtained which, even if it is not even is nevertheless at least symmetrical with respect to the cross section of the plastic foil web (i.e. transversely to the take-off direction thereof), thus enabling the plastic foil web to be subjected to the blowing action of air or gas as evenly as possible over the entire width of the blower nozzle.
However, this requires an increased outlay since two supply ducts are provided, which have to be supplied with hot gas or cooling gas (generally air) in each case on opposite sides, i.e. on both sides of the material web being advanced, in each case via a separate supply aperture. However, this results in relatively poor accessibility to the blower nozzle in particular if it is installed in an oven.
An essentially two-part veneer web drier has been disclosed, for example, in DE 30 35 417 A1. The nozzle box includes a perforated plate which runs obliquely from bottom to top, is provided with holes and divides the nozzle box into a pressure space and a suction space, the suction space being connected to the intake side and the pressure space being connected via the delivery side to circulating fans. Even a veneer web drier of this type does not result in the desired, completely even distribution and/or even gas outlet speed of the supplied hot gas flow over the entire length of the nozzle box.
In the case of the blowing device which is disclosed in DE 37 04 910 C1 or DE 36 26 171 C1 and is intended for blowing a treatment medium onto a material web moving in the longitudinal dir
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Patent Abstracts of Japan vol. 9, No. 121 (M-382), May 25, 1985 & JP 60 008037 A (Mitsubishi Jukogyo K.K.), Jan. 16, 1985, see abstract & Database WPI Section Ch, Week 8509 Derwent Pulbications Ltd., London, GB: Class AF, AN 85-052284 (09) & JP 60 008 037 A (Mitsubishi Heavy Ind. Co. Ltd.), Jan. 16, 1985 see abstract.
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Kittsteiner Hans-Jurgen
Maetze Michael
Bruckner Maschinenbau GmbH
Gravini Stephen
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