Fluid sprinkling – spraying – and diffusing – Rigid fluid confining distributor – Having interior filter or guide
Reexamination Certificate
1999-06-22
2001-02-27
Kashnikow, Andres (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Rigid fluid confining distributor
Having interior filter or guide
Reexamination Certificate
active
06193174
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to airlay fiber handling equipment such as an airlay web former and more particularly to controlling the air stream into the web former.
BACKGROUND OF THE INVENTION
In the airlay web forming process in use by E.I. du Pont de Nemours and Company (DuPont) in the manufacture of spunlaced fabrics sold under the trademark Sontara®, fiber is carried by a relatively fast-moving air stream to a screen conveyor forming a web of randomly arranged fibers. The commercial process is disclosed and described in U.S. Pat. No. 3,797,074 to Zafiroglu.
Upon investigation, it has been hypothesized that the air flow which carries the fiber to the screen conveyor is subject to eddies, vortices and other indicators of turbulence at the peripheral sides of the web which is undesirable. In accordance with Zafiroglu, the air that is used to carry the fiber is introduced through a system of large conduits and fans. Prior to receiving the fiber, the air flow is directed through screens and straighteners to provide a uniform flow substantially free of large-scale turbulence and vortices. Thereafter, the large volume, relatively slow-moving air flow is accelerated through a converging section or nozzle into a reduced cross sectional area conduit which is substantially flat and wide to be suited for laying down a wide web. It is believed that the acceleration nozzle of Zafiroglu creates, or allows the creation of the vortices and turbulence at the peripheral sides of the web which is believed responsible for certain defects.
U.S. Pat. 5,564,630 to Giles et al (assigned to DuPont) is directed to an improved nozzle over that of Zafiroglu by providing smoothly curving, low angle peripheral walls. The nozzle is particularly helpful in reducing edge defects which can result from vortices and turbulence. Regardless, considerable need remains for improvement of web properties.
U.S. patent application Ser. No. 08/760,119 now abandoned (also assigned to DuPont) is directed to combining the advantages of feeding carded fibers to an airlay. The air stream in that patent application is controlled by use of fans and a series of filters and air straighteners to create a laminar air flow. However, such an arrangement may present disadvantages in terms of space requirements and by making the maintenance of the cards especially difficult.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide means for controlling the air stream into an airlay web former arrangement which substantially reduces the defects of the web and overcomes the drawbacks of existent arrangements as described above.
These objects of the invention are accomplished by a device for directing air flow comprising a first conduit with an inlet and an outlet and having an upper curved wall surface and a lower curved wall surface wherein the bottom curved wall surface has a greater degree of curvature than does the upper curved wall surface so that the distance between the curved wall surfaces generally decreases and thereby substantially changes the direction of air flow from the inlet to the outlet. These objects of the invention are further accomplished by a device comprising the first conduit and a second conduit of similar configuration to the first conduit and wherein the first conduit and second conduit combine at their outlet areas to form a third single conduit.
REFERENCES:
patent: 2056782 (1936-10-01), Fosdick
patent: 3797074 (1974-03-01), Zafiroglu
patent: 3834869 (1974-09-01), Ancelle et al.
patent: 3856281 (1974-12-01), Bertolotti et al.
patent: 3914822 (1975-10-01), Wood
patent: 3932915 (1976-01-01), Contractor et al.
patent: 3996978 (1976-12-01), Rupaelian
patent: 4057487 (1977-11-01), Skrabak et al.
patent: 4186463 (1980-02-01), Marshall
patent: 5439358 (1995-08-01), Weinbrecht
patent: 5537718 (1996-07-01), Nagatsuka et al.
patent: 5564630 (1996-10-01), Giles et al.
patent: 5722830 (1998-03-01), Brandhorst et al.
patent: 9321 075 U1 (1992-02-01), None
patent: 568 748 A1 (1992-04-01), None
patent: 667 460 A2 (1995-01-01), None
patent: WO 97/22743 (1997-06-01), None
Freund Kenneth Stephen
Giles Andrew James
Staples Phillip Osborne
E. I. Du Pont de Nemours and Company
Hwu Davis
Kashnikow Andres
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