Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a deposition process using
intaglio printing plates and of the type in which the material
to be applied by deposition is injected through passages
passing through the plate to a recessed or intaglio design on
the printing surface of the plate.
The general object of this invention is to enable
material to be applied on a sheet on both faces simultaneously
in a single printing operation.
This is achieved by using intaglio printing plate
apparatus in accordance with the invention which comprises in
combination two intaglio plates attached to the top and bottom
press platens of the apparatus, respectively. One of the plates
is formed with passages passing through it for injection
of printing material to the recess and the other with air
bleed holes leading from the recessed design to atmosphere
through appropriate air bleed/restrictor devices. The sheet
materlal to which material is to be applied is then formed with
holes of appropriate size and position to enable the material
to be printed to flow from the recess in one plate through the
holes in the sheet to fill the intaglio recess in the other
plate. The sheet may thus be printed on both sides simul-
taneously in one stroke of the printing press, the applied
material filling the feed holes in the sheet.
The recessed design in one plate may be a mirror
image of that in the other plate.
The material to be applied may be injected or forced
through either the top or bottom printing plate using injector
or pump units and if desired a number of differing materials
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716
and colours may be applied simultaneously. As the air in the
recessed designs in the top and bottom plates has to be re-
moved it is convenient for the plate opposite to that attached
to the injector units to be provided with air bleed holes
preferably controlled by bleed/restrictor device(s) so that air
can bleed out through the plate but cannot be sucked back into
the recessed aesign.
The holes in the sheet on which material is to be
applied may be positioned as required for effective performance.
These are best located at least at points of change of direction
of the design to be applied where there is maximum resistance
to flow.
The holes should be big enough to allow flow there-
through of the material to be applied when this material is
under pressure but small enough to prevent material flowing
through the holes under gravity when for example the deposition
operation is finished and the sheet material is lifted from
the lower plate. As an example the feed holes may be from
10-30 thousands of an inch in diameter.
The bleed/restrictor device may comprise a member to
be secured to the "bottom" printing plate and formed with
passages to communicate with the air bleed holes in the "bottom"
plate. The holes in the plate are preferably relatively
small e.g. from 0.040" to 0.005" in diameter (preferably 0.020")
and provide flow restriction and in this case the passages in
the member will have a sufficiently large cross-section to
allow flow of applied fluid and entrapped air. ~lternatively
well-known non-return valve means may be provided for example
that described in the specification of our co-pending Canadian
application 218,961.
The process in accordance with the invention has been
found to be particularly useful for applying sealant material
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onto the top and bottom faces of gas}cets. Use of the process
for this purpose halves the time and cost of depositing coat-
ings on double-sided gaskets and avoids the necessity of having
to cure the gasket twice (to set the sealant or coating
material).
The invention will now be further described by way of
~xample with reference to the accompanying drawings in which:-
Fig. 1 is a schematic view of intaglio printingapparatus adapted for the process of this invention.
Fig. 2 is an exploded cross-sectional view of an
intaglio die plate used in the process of the invention.
Fig. 3 is a cross-sectional view of the "bottom"
printing plate used in the process of the invention attached
to one embodiment of bleed air flow control device; and
Fig. 4 is an exploded perspective view corresponding
to Fig. 3.
Referring to Fig. 1, an upper intaglio plate 10 for
depositing material in a pattern is supported from an upper
support 12 mounted on an upper press platen 13. The press
platen 13 cooperates with a lower press platen 14 which in
turn supports a lower or bottom intaglio plate 16 and a bleed
air flow control device 18. The sheet on which material is to
be applied is placed between the plates 10 and 16. In the
specification, the material to which material is to be applied
will be described as a sheet of paper but it will be understood
that the invention is applicable to any material to which a
design is to be applied whether or not of paper. For example
it may be a sasket to which a sealing compound is to be applied.
In the apparatus of Fig. 1, paint, sealing compound,
3~ or other applied fluid to be printed, is injected through the
printing plate 10 by a plurality of injector units 20, three
such units being illustrated in the drawings for applying three
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different colours or types of compound if desired, or, alter-
nati~ely each may apply a similar compound. Each injector unit
supplies fluid to one intaglio recess in the face of the plate.
The injector units 20 are each supplied from a cor-
responding fluid reservoir 22. Each injector unit 20 is con-
nected to a corresponding one of the reservoirs 22 by a flexible
conduit 24 which conducts fluid from the reservoir to the inlet
of the injector. I~hile the reservoirs 22 may be under pres-
sure, preferably the feed from the reservoirs 22 is a gravity
feed.
The injector units may each comprise a piston which
works as a pump so that when the platens 13 and 14 are moved
together material in the injector is forced against and through
the die plate 10.
Referring to Figure 2 the intaglio printing plate 10
is formed with passages 26 (only two of which are shown for
clarity) passing through its thickness and communicating with
a recessed design 28. The injector or pump units 20 are con-
nected to the passages to force the material to be applied
through the plate into the recess.
The intaglio printing plate 16 which is similar to
the plate 10, is connected to the lower platen 14 of the print-
ing press and the recessed design 30 is a mirror image of the
design 28 of the upper plate 10, the plates 10 and 14'being
aligned.
The sheet material e.g. gasket material, to be printed
is illustrated at 32 and is formed with a number of feed
holes 34 passing through it.
On operation cf the press sealant material is fed
through the holes 26 into the recess 28 of the top plate and
sealant material is applied to the top surface of the gasket 32
at those places where an additional height of sealant is
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required, sealant material then passes throuyh the feed
holes 34 and into the recessed design 30 of the lower printing
plate 16. Sealant is thus also applied to the bottom surface
of the gasket 32 in the same operation.
The air from the recesses in the two plates and in
the feed holes 26 and 34 bleeds out through the lower plate 16
through air bleed holes 36.
These bleed holes have a diameter of between 0.040"
and 0.005" preferably 0.020" so as to restrict the air flow
whilst providing a reasonable exit passage. The holes com-
municate with passages 38 in the bleed air flow control
device 18, the passages 38 leading to a main exit passage 40
which is open to atmosphere at each side of the plate (see
Figures 3 and 4). This arrangement provides restriction to
flow through the holes 36 but the passages 38, 40 are of
sufficient size to allow unrestricted flow of excess fluid and
entrapped air. The material of the control device 18 should be
incompressible, dimensionally stable and resistant to the
fluid to be applied. Steel and "Tufnol" (RTM) have been found
to be suitable.
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