U.S. patent number 3,711,960 [Application Number 05/175,052] was granted by the patent office on 1973-01-23 for web dryer.
This patent grant is currently assigned to Overly, Inc.. Invention is credited to Wm. F. Overly, Kenneth J. Pagel.
United States Patent |
3,711,960 |
Overly , et al. |
January 23, 1973 |
WEB DRYER
Abstract
A plurality of airfoil nozzles are disposed alternately on
opposite sides of the moving web, each nozzle having a flat face
generally parallel to the web and ending in a substantially
90.degree. corner of the plenum chamber.
Inventors: |
Overly; Wm. F. (Winneconne,
WI), Pagel; Kenneth J. (Neenah, WI) |
Assignee: |
Overly, Inc. (Neenah,
WI)
|
Family
ID: |
22638652 |
Appl.
No.: |
05/175,052 |
Filed: |
August 26, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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89744 |
Nov 16, 1970 |
3650043 |
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Current U.S.
Class: |
34/641;
242/615.11; 226/196.1 |
Current CPC
Class: |
D21F
5/00 (20130101); B41F 23/00 (20130101) |
Current International
Class: |
B41F
23/00 (20060101); D21F 5/00 (20060101); B65h
017/32 () |
Field of
Search: |
;34/156 ;226/7,97 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Knowles; Allen N.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation in part of application Ser. No.
89,744, now U.S. Pat. No. 3,650,043 filed on Nov. 16, 1970 by the
present applicants for Airfoil Web Dryer, and copending herewith.
Claims
We claim:
1. A web dryer employing a plurality of airfoil nozzles disposed
alternately in series on opposite sides of the moving web in a
drying zone, and in which the airfoil surface of each nozzle
extends for a substantial distance generally parallel to the web
and terminates in a sharp edge to release the air in a direction of
flow along the web.
2. The web dryer of claim 1 in which the airfoil nozzles on each
side of the web are spaced apart a greater distance than the width
of a nozzle to ensure avoidance of interference between alternate
nozzles with respect to control of web movement.
3. A web dryer employing a plurality of airfoil nozzles disposed
alternately in series on opposite sides of the moving web in a
drying zone, said nozzles on each side of the web being spaced
apart a greater distance than the width of the intermediate nozzle
on the opposite side of the web to provide a control of web
movement by each nozzle generally free from interference from
nozzles on the opposite sides of the web.
Description
BACKGROUND OF THE INVENTION
This invention relates to web dryers as employed in paper and
synthetic web manufacture and as employed in the printing and
coating of papers and synthetic webs or films.
In the application of airfoil nozzles on opposite sides of the web
in a drying zone wherein the nozzles support or position the web as
the same moves therebetween, difficulty has been encountered in
keeping the web planular as distinguished from a tortuous or wavy
path through the dryer.
It has generally been considered desirable to remove the spent air
from the dryer zone and from further contact with the web as
rapidly as possible.
However, where the plenum chamber of each airfoil nozzle had a
rounded exhaust corner which had a Coanda effect it was found that
the air followed the curvature of the corner and left the web
abruptly, thereby tending to induce a wave motion in the web which
was undesirable.
Disposition of the nozzles in direct opposition with the web
therebetween tended to produce a more objectionable flutter in the
web as it left the space between the nozzles, and depending upon
inequalities in the forces involved still resulted in the
undesirable wave characteristics.
Attempts to place the nozzles on each side close together or to
have adjacent nozzles provide a discharge flow in opposite
directions along the web only served to accentuate the wave
formation.
Applicants are unaware of any prior art relevant to the problem
involved other than their attempts to solve the problem as above
explained.
SUMMARY OF THE INVENTION
In carrying out the present invention the airfoil nozzles on each
side of the web are spaced apart a greater distance than the width
of a nozzle and are disposed alternately in series with respect to
the nozzles on the opposite side of the web so that each nozzle is
enabled to control the movement of the web in the zone of the
nozzle without interference from nozzles on the opposite side of
the web.
Additionally each airfoil nozzle is designed with a sharp trailing
corner or edge of the plenum chamber or airfoil surface to thereby
effect a release of the web so that it can move into the zone of
and be freely controlled by the adjacent airfoil nozzle.
The sharpness of the trailing edge of the airfoil surface of the
nozzle should be such as to avoid any appreciable Coanda effect
with respect to the air passing out from under the edge.
BRIEF DESCRIPTION OF THE DRAWING
The accompanying drawing illustrates the best mode presently
contemplated by the inventors for carrying out the invention.
In the drawing:
FIG. 1 is a top plan view of a web drying operation illustrative of
the drying zone;
FIG. 2 is a side elevation of the web dryer of FIG. 1; and
FIG. 3 is an enlarged section of a portion of the dryer with
adjacent airfoil nozzles and showing the web passing the same and
the flow of air as it effects the web.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to the preferred embodiment illustrated in the
drawing, the web 1 is supplied to the dryer zone 2 by the roll 3
and is withdrawn from the dryer zone 2 by the roll 4.
The course of movement of the web 1 through zone 2 from roll 3 to
roll 4 is generally planular.
In the zone 2 the web 1 is treated by a plurality of separate air
flows induced by a series of airfoil nozzles 5 disposed alternately
above and below the web, as illustrated in FIGS. 1 and 2.
The arrangement of the nozzles 5 is generally the same as that of
nozzles 4 illustrated in FIGS. 1 and 2 of the copending application
referred to above and each nozzle comprises a plenum chamber 6
extending transversely of the web 1 for its full width and supplied
with air by a central lead conduit 7 in its back side.
The chamber 6 is generally rectangular in cross section and has an
airfoil nozzle 8 at the forward edge of its face 9.
The nozzle 8 comprises a slot extending generally for the length of
chamber 6 and having its inner side curved as at 10 to constitute
an airfoil surface merging into face 9.
The face 9 of the chamber 6 extends generally parallel to the web 1
and constitutes an extension of the airfoil surface 10 along which
the air flows from nozzle slot 8.
As explained in the above identified copending application the air
passing through the slot of nozzle 8 at a high velocity follows the
curved airfoil surface 10 to the space between face 9 and web 1
where the air becomes turbulent and continues in this manner to the
trailing edge 11 of face 9.
If the edge 11 is rounded sufficiently to create a Coanda effect
the air will tend to follow the curvature as illustrated in FIG. 3
of the copending application and to draw the web upwardly therewith
in a wave pattern which tends to interfere with the desired
planular movement of the web and with control of the web by the
adjacent airfoil nozzle.
The present invention is based upon the discovery that the
undesirable wave pattern of the web can be avoided by making the
trailing edge 11 of face 9 reasonably sharp as illustrated herein
and thereby substantially eliminating the Coanda effect at this
location.
With a sharp trailing edge 11 the air tends to follow the web 1 as
it leaves the space between face 9 and the web, as shown in FIG.
3.
The next adjacent plenum chamber 6 having a nozzle 8 is spaced from
the trailing edge 11 a distance substantially greater than the
width of a plenum chamber 6 to provide adequate space 12 through
which the air discharging at high velocity from beneath the edge 11
can be withdrawn from the drying zone 2.
The web is controlled in its travel across space 12 between two
adjacent plenum chambers 6 by a plenum chamber 6 and its nozzle 8
on the opposite side of the web as determined by the alternate
arrangement of the nozzles previously referred to.
The air being discharged from beneath the trailing edge 11 enters
the space 12 and releases the web 1 so that it is then subject to
control in position by the airfoil nozzle disposed on the opposite
side of the web.
Various modes of carrying out the invention are contemplated as
being within the scope of the following claims particularly
pointing out and distinctly claiming the subject matter which is
regarded as the invention.
* * * * *