Textiles: fiber preparation – Working – Carding
Patent
1999-04-02
2000-07-11
Neas, Michael A.
Textiles: fiber preparation
Working
Carding
19204, 406 82, D01G 1540
Patent
active
060853891
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to apparatus for forming a lap of stock fibers, and more particularly intended for positioning upstream from a textile machine such as a card, for the purpose of feeding it continuously with textile material. The invention relates more particularly to an improvement relating to taking up the densifying air flow at the outlet from the feed chimney of such apparatus.
Apparatuses for forming a lap of stock fibers, such as those used for loading a card, usually comprise a feed chimney which is open at its top and bottom ends, and which is provided in its lower portion with one or more air exhaust openings. Such apparatuses also include means enabling the feed chimney to be fed via its open top end with stock fiber material, means for taking up the stock fiber material, which means are of the feed roller type located at the outlet from the bottom end of the feed chimney, and means for providing forced circulation of a flow of air for densifying the fiber material between the top portion of the feed chimney and the exhaust opening(s).
Manufacturers and users of the above-mentioned apparatuses are continually looking for ways of obtaining a lap at the outlet of the feed chimney that is of a thickness that is as uniform as possible over the entire width of the feed chimney. To this end, it is desirable in such apparatuses to obtain a distribution of densifying air within the feed chimney that is as uniform as possible, firstly by providing a system of baffles upstream from the feed chimney for the purpose of breaking up the flow of densification air and distributing it uniformly over the entire width of the inlet of the feed chimney, and secondly by taking up the densification air flow from the lower portion of the feed chimney over the entire width thereof, with the exhaust opening(s) extending substantially over all of said width.
The flow of densification air at the outlet from the feed chimney is taken up by suction into an air takeup duct, and is then either recycled in a closed circuit by being reinjected into the feed chimney, or else is exhausted to ambient air, possibly after being filtered.
German patent application DE-A-3239524 and the equivalent U.S. Pat. No. 4,394,790 teach interposing an expansion chamber between the suction takeup duct and the feed chimney. To prevent variations in the suction source which is connected to said expansion chamber via the air takeup duct having an effect on the level of fibers in the chimney, it is recommended in those publications to control the pressure inside the expansion chamber. This pressure control is obtained by providing means for admitting air into the expansion chamber so as to enable ambient air to be admitted selectively into the expansion chamber when the suction within the expansion chamber is excessive. In a particular variant, the air admission means are constituted by an opening fitted with a valve.
In presently known apparatuses, although the air is uniformly distributed at the inlet to the feed chimney, and although provision is made for densification air to be exhausted over the entire width of the feed chimney, there nevertheless remain in practice one or more zones across the width of the feed chimney where fibrous material accumulates preferentially inside the feed chimney, thereby spoiling the uniformity of the lap formed at the outlet from the chimney.
In particular, in the apparatus described in German patent application DE-A-3239524 or U.S. Pat. No. 4,394,790, the forced takeup of air inside the expansion chamber influences the flow of air at the outlet from the feed chimney, and thereby influences the level of fiber material inside the chimney.
The object of the present invention is to improve those prior apparatuses for forming a lap of stock fibers as to reduce, and if possible eliminate, the zones of preferential accumulation of material inside the chimney, thereby obtaining a lap that is more uniform across its entire width.
The solution of the invention consists essentially in seeking to improve the way i
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Brabant Marc
Catry Xavier
Doring Reinhold
Vanbeselaere Christian
Neas Michael A.
Thibeau
Welch Gary L.
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