Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present inven-tion relates to an apparatus and
method for applying flexographic printing plates to the
plate cylinders of printing machines.
It is essential that the flexographic plate be
accurately positioned on each plate cylinder in order that
images printed in different colours by different cylinders
are in registxation.
Canadian Patent 975,217 issued to Chromax Limited
on Septel~ber 30, 1975 shows a machine for such a purpose
in which a flexographic printing plate is first positioned
on a slide. The slide is then mo-~ed relatively to a
printing cylinder and pressure sensitive adhesive on the
reverse side of the flexographic plate causes it to stick
to and wrap around the cylinder ln reglstration.
The present invention provides an improved, compact
and simple apparatus which first positions the flexographi~
printing plate on a register cylinder by means of register
pins and then transfers the plate to a plate c~linder. The
plate is retained on tha plate cylinder surface magnetically
or by an adhesive substance.
Specifically the invention relates to apparatus for
mounting a flexographic plate in registration on a plate
cylinder, the flexographic plate being providea with
registration holes at one end thereof. The apparatus
comprises: a register cylinder capable oE controlled
rotation and provided with a row of apertures to receive
~retractible registration pins at selected locations, means
supporting a flexographic plate with the one end supported
by the register cylinder and the registration holes engaged
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by re~istration pins, means for first rotating the register
cylinder a precise amoun-t whereby the flexographic plate is
positioned for transfer to a plate cylinder, a movable plate
cylinder support for receiving a plate cylinder at a
predetermined rotational position, whereby the plate cylinder
may abut the flexographic plate and register cylinder after
the register cylinder has performed its first rotation, and
means for further rotating the register cylinder when
abutting the plate cylinder whereby the flexographic plate
is transferred to the plate cylinder in registration.
In its method aspect the invention relates to a
method for moun~ing a flexographic plate in registration on
a plate cylinder by use of a register cylinder capable of
controlled rotation and provided with a row of apertures to
receive retractible registration pins at selected locations~
The method comprises the steps of: positioning the
flexographic plate with holes at one end engaging the pins
in the register cylinder, rotating the register cylinder a
precise amount, positioning the plate cylinder at a
predetermined rotational position abut-ting the flexographic
plate and register cylinder, retracting the registration
pins and rotating both the register cylinder and plate
cylinder whereby the flexographic plate transfers to the
plate. cylinder in registration~
A specific embodiment of the invention will now
be described in conjunction with the accompanying drawings,
in which:
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Figure 1 is a plan view of -the apparatus of the
inventlon;
Figure 2 is a fron-t view of the appara-tus shown in
Figu.re 1 with the positioning tray shown in phantom;
Figure 3 is a side view of the apparatus showing
~he locking mechanism for each of the cylinders; and
Figures 4 - 7 show the sequence of operation of
the apparatus.
Desc.ription of the Preferred Embodiment
Figures 1 and 2 show two views of the pla-te mounting
apparatus of the present invention~ An underlying support or
base member 10 has bearing journals 13 supportlng stub support
shafts 12 of a register cylinder 11. At the end of the le~t
hand stub support shaft, referring to Figure 1, there is
pro~ided an index plate 22, a hand wheel 23 and a cam control
knob 24. Index plate 22 is used for locking the register
cylinder in positions spaced exactly 180 apart, as will ~e more
fully described below. Hand wheel 23 is used by an operator to
rotate the register cylinder during use and cam control knob
24 adjusts the position of an internal cam 25. Cam 25
cooperates with a series of holes 26 which are adapted to
receive register pins 27. In the position of the cam shown
in E~igure 1 the regi.ster pins are maintained with an end
protruding outwardly from the cylinder, to retain a flexographic
plate 33 thereon as shown in phantom in Figure 2, and i.n the
other position of the cam it permits the pins to be wholly
retracted within the cylinder. Cylinders with retractable
pins are known such as those shown in Canadian Patent No.
724,050, issued December 21, 1965 to Raybuck and Canadian
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Patent No. 1,027,803, issued ~arch 14, 1978 to Gubela.
Bearing journals 14 are provided adjacent to the
register cylinder to receive a plate cylinder 16 Erom a
conventional printing machine. Cylinder 16 has stub support
shafts 15 and is adjusted -to fit axially by knob 31 of an
adjustment mechanism 30. Normally, the print cylinder is
provided with a helical drive gear 32, at the end opposite
from adjusting mechanism 30, and this is used to lock the
cylinder against rotation as described more fully below.
The plate cylinder bearing journals 14 are movable
on guide members 17 so that the plate cylinder can be mo~ed
towards and away from register cylinder 11 under control of
the operator by using handle 21 controlling threaded roa 200
Adjustable supports to receive a removable plate cylinder
are shown, for example, in U.S. Patent No. 3r347,161, issued
October 17, 1967, to Lenk and in U.S. Patent No. 3,390,633,
issued July 2, 1968, to BroughtonO
Figuxe 3 shows the mechanism employed to lock the
plate cylinder and register cylinder against rotation at
selected times during operation of the apparatus A movable
locating pin 34 engages with a tooth of helical year 32~
~he position of pine 34 is controlled by a screw thread driven
by knob 35 and may be locked in position by ~ further knob 36
So Ear as the register cylinder is concerned, inde~ plate 22
is provided with opposed locking recesses 37 and 38 spaced
exactly by 180 which cooperate with a locating pin 40 carried
by a slidable pl.ate 41. Plate 41 is spring biased so as to
be urged into engagement with the index plate. It can be
pulled downwardly by a tongue portion 42 extending at right
~A
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angles to the plane of Figure 3. Plate 41 can be held in
the retracted position by a spacer block 43 which may be
pivoted to occupy the space above tonyue 42 by means of a
handle 44.
Referring now to Figures 4 - 7, a positiorling tra~ 45
extends downwardly towards the upper part of register
cylinder 11. An adjustably mounted, channelled guide member
46 is carried by base 10. The function of the guide member
is to maintain tension in the flexographic plate and guide
it as the register cylinder rotates. The spacing between
the register cylinder 11 and the exit portion of guide member
32 can be varied to accommodate flexographic plates of varying
thickness by a screw adjusting mechanism controlled by knob 47.
In operation, a flexographic plate 33 is positioned
face downwardly on the posi.tioning tray 45 and register holes
at one end of the flexographic plate are engaged by pins 27
placed in appropriate holes 26 in register cyli~der 11. The
apparatus is then in the position shown in Figure 4. The
register cylinder is then rotated through 180 to the position
shown in Figure 5 where the fle~ographic plate is supported
by register pins 27 and by the guide member 46.
The plate cylinder 16 is then adjusted by means of
handle 21 to abut the flexographic plate 33 2nd the register
cylinder 11 as shown in Figure 6. An adhesive surface 48
provided on plate cylinder 16 engages the rear surface of
flexographic plate 33 and under the pressure of the plate
cylinder, register pins 27 retract into holes 26 in re~ister
cylinder 11.
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Plate cylinder 16 is then unlocked for rotation and
register cylinder 11 is further rotated leading to the
situation shown in Figure 7 in which flexographic plate 33
has adhered to plate cylinder 16 in registration whereupon
plate cylinder 16 may be removed and utilized in printing
apparatus. Register cylinder 11 may then be returned to its
original position ready to receive the next flexographic
plate.
Thus, there has been described an apparatus and
method useful for mounting flexographic plates in registration
on a plate cylinder. It is contemplated that the ~lexographic
plate can adhere to plate cylinder by magnetic attraction as
well as by other forms of adhesionO
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