Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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IMPROVED PRESS SPRAY`DAMPENER
Background of the Invention
The lithographic process for printing utilizes an
image carrier that is essentially planographic, that is,
S the image area on the printing plate is essentially on the
same plane as the non-image area. Thus, lithography
differs from the well known relief processes where the
printing areas stand in a totally different plane from the
non-image areas. Since the image carriers or plates are
planographic, success of the lithographic process depends
upon the use of plates that have been treated so that the
image areas are hydrophobic, or not receptive to water, and
the non-image areas are hydrophyl~c, whioh means that they
are receptive to water. Since successful lithgraphic
printing relies upon the presence of water to preclude the
non-image areas from acquiring ink, it is apparent tha~
fluid dampening of the printing cylinder is an essential
element to successful performance of the printing function.
In the past, the most common means for applying water
to lithographic plate cylinders involved the use of water
fountains, a vibrating distributor roller and a plurality
of form rollers that transferred the fluid dampening medium
from the vibrator roll to the plate. While the non-image
areas have been characterized as hydrophylic and receptive
to water, it will be understood that frequently minor
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amounts of agents are added to the water for a variety of purposes so that in
a technical sense, the dampening medium does not always consist solely of
water. As print quality and printing speed demands on modern web-fed rotary
presses have increased, the need for improved dampener performance has been
experienced. This invention provides positive, accurate, and reliable control
of dampening fluid application. Obviously to obtain commercially feasible
dampening by the System, the construction and operation of the spraying
mechanism are of prime significance.
A principal object of this invention is to provide an improved
manifold spray dampening unit for accurately supplying dampening fluid to a
press printing couple. A helical groove of relatively large cross-section area
is used to provide flow resistance in each fluid outlet, rather than a very
small, easily plugged hole.
Another object of this invention is to provide an improved manifold
spray dampening unit which is self-cleaning and which individual spray head
~mits can be closed when not needed.
According to the present invention there is provided in a system
for delivering dampening fluid to a rotating cylinder of a web fed rotary press,
an improved manifold spray unit comprising:
(a) an elongated manifold body defining elongated first and second pas-
sages for conducting flow of air and dampening fluid along the length of said
manifold and defining a plurality of lateral openings extending through said
manifold and through said first and second passages in a direction substantially
normal to the axes thereof;
(b) individual spray head means mounted within each lateral opening in
said manifold body, each said spray head means including:
~i) elongated first means having enlarged inner and outer end
portions that engage the inner walls of said lateral opening and which defines
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a through bore of varying diameters terminating in a nozzle opening and which
further defines passages connecting said first longitudinal air passage to the
exterior of said spray head;
(ii) an orifice nozzle mounted within the bore of said elongated
first means adjacent the nozzle opening;
~ iii) an elongated capillary rod mounted within the bore of said
elongated first means for axial movement therein and being configured such that
when positioned in a forward position, no flow of dampening fluid can cccur;
~c) closure means secured to said manifold body to seal the inner end
of said lateral opening in said manifold body; and
(d) latching means secured to said manifold body to retain said capil-
lary rod in its forward, closed position when desired.
Other objects and advantages of this invention will be in part
obvious and in part explained with reference to the accompanying specification
and drawings in which:
Brief Description of the Drawings
Figure 1 is a sectional view through a spray head of this invention
showing the operating parts in positions where dampening fluid can be ejected;
Figure 2 is a sectional view similar to Figure 1 showing the spray
in a closed position;
Figure 3 is a partial front elevation of the manifold spray system;
and
Figure 4 is a top elevation, partly sectional, to show the manner
in which a spray head is mounted with the spray manifold.
Description of the Preferred Embodiments
To more fully understand the present system for delivering
dampening fluid to a rotating cylinder of a web
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fed rotary press, reference is made to the drawings and, in
particular, to Figures 1 and 3 in which the numeral 10 denotes an
elongated manifold. Manifold 10 defines a first elongated passage
11 for conducting the flow of air from an appropriate source to
each of the individual spray head means located along the length of
the manifold. Also defined by the elongated manifold body 10 is a
second elongated passage 12 which provides for the flow of dampen-
ing fluid along the length of the manifold. It will be seen that
the manifold also contains a plurality of lateral openings 13 which
extend through manifold 10 and through first and second elongated
passages 11 and 12 in a direction which is substantially normal to
the axis of passages 11 and 12. For a description of a press spray
dampening system which can advantageously utilize the manifold
spray of this inventionr reference is made to applicant's co-pending
Canadian application ~erial No. 373,972, filed on even date herewith
and assigned to the same assignee as this invention.
Within each lateral opening 13 there is mounted individual
spray head means 15 that provides for the appropriate mixing of
dampening fluid and air so that a finely controlled spray of dampen-
ing fluid can be e~ected against a dampener roll in the press. Thespray head means includes an elongated first means 16 which has an
enlarged inner end portion 17 and an enlarged outer end portion 18.
Both enlarged portions i7 and 18 engage the inner walls of lateral
opening 13, the enlarged inner end 17 effectively acting to
preclude communication between elongated passage 11 and 12. The
elongated first means 16 defines a through-bore 20 which varies in
diameter throughout its length and which terminates in a nozzle
opening 21. Formed in the outer enlarged portion 18 are a pair of
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air passages 22 that extend between air passage 11 and the
exterior of the spray head. It can be seen that passages 22
converge, at an acute angle, to a point located just forwardl~
of the nozzle opening 21.
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Referring to Figs. 2 and 4, it will be seen that an
orifice nozzle 25 is mounted within bore 20 of said
elongated first means 16. This nozzle has a rearwardly
facing portion of relatively large internal diameter 26 and
an outwardly facing extension which defines a small spray
opening 27.
The spray head means 15 further comprises an
enlongated capillary rod 30 that is mounted within the bore
of the elongated first means 16 for axial movement within
member 16. This elongated capillary rod comprises a
needle-like inner portion 31 of a diameter which is only
slightly less than the diameter of spray opening 27. The
purpose for providing extension 31 is to enable opening 27
to be freed of any blocking simply by moving capillary rod
3û into the position shown in Fig. 2.
Capillary rod 3û also includes an intermediate portion
32 ha~ing a diameter slightly less than the diameter of the
intermediate secton of through-bore 20 and an outer portion
33 of the same diameter as intermediate portion 32. ~y
referring to the drawings, it will be noted that the
intermediate portion 32 and outer portion 33 are of the
same diameter and are separated by a portion 34 which is of
lesser diameter than the diameters of portions 32 and 33.
After outer portion 33, the capillary member extends
rearwardly beyond the rearmost surface of manifold 10.
Intermediate portion 32 of the capillary rod 30 is
formed with a precision metering groove 35 so that when rod
30 is in the position shown in Fig. 1, dampening fluid can
flow from elongated passage 12, through the metering groove
and out through spray opening 27. Normally, capillary rod
30 would be kept in the open position by means of helical
spring 40 that is compressed between a rearwarly facing
wall 41 in the elongated first means 16 and a collar 42
that is secured to the outer portion 33 of capillary rod 30.
While the forward end of lateral opening 13 is closed
by the enlarged outer portion 13 of spray head means 15,
the opposite end is closed by means of a closure member 45
through which the rearward portion of capillary rod 30
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extends. Qppropriate 0-rings 46 are utilized in the manner
indicated to effect sealing to prevent the undesired escape
- of air or of dampening fluid. rhe spray head means 15 i.s
held completely within the lateral opening of the manifold
10 by means of plates 47 and appropriate threaded fasteners
48.
It will be seen that on the rearmost side of
manifold 10 there is provided a latching element 50 that is
secured to the manifold by one of the threaded
fasteners 48. The latching element 50 may be an elongated
bar with an upstanding leg 51 extending the length of
manifold 10 or individual elements may be provided for each
of the spray heads.
Finally, it will be noted that the rearmost end of
capillary rod 30 is provided with a knob 55 that includes a
tang 56 that can be used to hold the capillary rod in its
forwardmost position (see Fig. 2) so that no ~low of
dampening fluid from passage 12 through the metering groove
can occur. rhis interruption of flow from the spray head
is effected by the forward end of the outer portion 33
sliding into that portion of through-bore 20 that is of
intermediate diameter.
Although the present invention has been described in
connection with a preferred embodiment, it is to be
understood that other modifications and variations may be
resorted to without departing from the spirit and scope of
the invention as those skilled in the art will readily
understand. Such modifications and variations are
considered to be within the purview and scope of the
invention and the appended claims.
