Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
36~ii3~
PRINTING CYLINDER WITH RETR1~CTABLE PI~TE
REGIS~E~ PIN P.ND ME'rHOD O~ ASSEMBLY
Specification : - :
This application relates to a plate register pin
~or positionlng a printing plate on a print:ing cylinder and
more particularly to a register pin which is movable between
extended and retracted positions and to a method o~ cylinder
assembly.
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Backround of the Invention
In 60me pr~ntlng applica~ions the printing plate ~;.
(or blanket) is mounted on a magnetic cylinder and is he~d
on the 6urface o~ the cylinder by magnetic attraction. If
precise positionlng o~ the plate on the cylinder is impor-
~ tant, the cylinder may have one or more register pins which~ ~.
- 15 locate the plate. One such construction is shown in Rosta~
. U.S. Patent No. 3,919,937~
Some printing plates are quite thin, for example,
less than .020" in thickness. The register pin should not
: extend above the plate surface. With such a small pin
height, engagement of the plate edge with the pin while ma- :
nipulating the plate o~ the magnetic cylinder surface is
difficult. Moreover, to avoid having a longitudinal gap ~;
between the plate edges, it i6 necessary that both edge~ be
notched to ~it the pin.
Summary o~ the Xnvention
In accordance with the invention, the cylinder is
proviAed with a retractable register pi~.
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~ nother feat~re of the i~vention is that the hole in
the cylinder is deflned by a bushing fitted in the cylinder,
the register pin being movable radially of the cylinder in -the
bushing. An O-ring on the pin moves in a groove on the inner
wall of the bushing, limiting the movement of the pin outwardly
of the cylinder. A second O-ring on the pin grips the inner
wal.l. oE the bushing, preven-ting rotat.ion of the pin.
A further feature of the invention is the method oE
assembly of a retractable plate register pin with a printing
cylinder, comprising drilling a hole in an outer surface
portion of the cylinder, inserting a bushi~g and pin in the
hole, with the pin retracted in the bushing, the bushing and
pin extending to abo~e the outer surface portion of the
cylinder, finishing the outer surface portion of the cylinder,
and causing the bushing and pin to be flush with the finished
surface of the cylinder.
Further features and advantages of the invention will
readily be apparent from the following specification and from
the drawings, in which:
Figure 1 is a diagrammatic perspective of a cylinder
with register pins and a printing plate;
Figure 2 is an enlarged fragmentary plan of the
cylinder, register pin in extended position and one edge of a
printing plate;
Figure 3 i9 a section taken along line 3 - 3 of
Figure 2;
Figure 4 is a view similar to Figure 2 with the pin
retracted and the pl.ate wrapped around the cylinder;
Figure 5 is a section taken along line 5 - 5 of
Figure 4;
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Figuxe 6 is a diagram of the pin and a pull tool
u6ed in removing the pin from the retracted to extended po-
sition; and
Yigure 7 illustrates the manufacture of the cylin-
der and register pin.
A magnetic cylinde~ for a printing plate or ~or an
o~set blanket i~ shown in Peekna Canadian application
Serial No. 522,326 filed November 6, 1986, and assigned to
the assignee of this invention. The retractable register
pin of this application is particularly suited for use in
mounting a printing plate on the Peekna p~inting plate
cylinder. The register pin may also be used in mounting the
blanket and carrier plate on the blanket cylinder, as wel~
as with plates or blankets on other magnetic cylinders.
In Figure 1 a magnetic cylinder ~0 ha~ shafts 11
for mounting in a press. ~egister pins 12 extend radially
outwardly ~rom the cy~inder surface. A printing plate 13 of
ferromagnetic material has an edge 14 with notches 15 which
engage the register pins 12 locating the plate circumferen-
tially and longitudinally of the cylinder.
The register pin ~2 i6 shown in extended posit,ion
in ~igures 2 and 3, and in retracted position in ~igures 4
ana 5. With the pin 12 extended, the edge 14 of plate 13 is
positioned against the 6~de o~ the pin. The plate i6
2S wrapped around 'he cylinder 10, the pin 12 retracted as seen
in Figure~ 4 and 5 and the edge 1~ o~ the plate lies adja-
cent notched edge ~4.
With a pin diameter o~ the order o~ inch, the
notch ~5 may have a depth o~ the order o~ 1/32 inch. The
small gap in the plate surface is negligible.
The pin 12 is cylindrical and iB movable radially
of the cylinder in a bushing 20 which extends into the cyl-
inder through the magnetic structure 21, brass sleeve 22 and
into the iron core 23 of the cylinder. There are two spaced
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apart groove~ 26, 27 on the outer surface of pin 12 in which0-rings 28, 29, respectively, are received. o-ring 29 îs
seated in an elongated groove 30 in the inner wall of bush-
ing 20. 0-ring 29 engages the upper end of grooves 30 lim-
S iting the movement of pin 12 outwardly to its extended posi-
tion, as ~een in Figure 3. For a plate thickness of .015 to
.02 inch, the register pin in its extended position may be
.05 inch above the cylinder surface. Inward movement of the
register pin 1~ i~ limited by engagement of the inner end o~
the pin with the inner surface 32 of the hole in cylinder
core 23.
0-ring ~8 i8 compres6ed against the inner wall Or
bushing 20 and pre~ents rotakion of ~he register pin. The
0-rings are pre~erably on the outer surf~ce of the pi n rath-
er than on the inner surface of the bushing to facilitatemountiny and replacement. The inner end of ~he pin is ta-
pered at 33 to facilitate insertion of the pin into the
o-rings.
Register pin 12 has a longitudinal bore 34 extend-
ing therethrough to relieve fluid pressure inside bushing20. A shoulder 35 $n the bore is engageable by the head 36
of a tool 37, Figure 6, to pull the pin to its extended po-
sition. A hole 40 extends laterally through the wall of pin
12 to the longitudl~al bore 34 at a point between the
25 o-ring~ 28, 29. ~h$~ hole reliev~s fluid trapped between
the pln a~d the inne~ wall of ~ushing 2~.
~ he cylinder i~ ~abricated with the magnetic
struature 21 overslze. The ~ur~ace of the cylinder is then
ground or otherwise cut to the desired dimen~ion~ The reg-
ister pin 12 i8 assembled wikh the cylinder as a part ofthis operation. Fir~t, a hole is drilled in the cylinder to
receive bushing 200 ~he bushing, which is longer than the
desired finished dimension, i8 inserted in the hole with its
lower end seated on the surface 32 at the base of the hole
in the cylinder. Register pin 12 with the 0-rings 28, 29
is3~
mounted thereon iB then in~erted into bushing 20 with its
lower end seated on the euxface 32. The length of pin 12 is
~uch that it~ outer end i8 outside the finished surface of
the cylinder. The cylinder, bushing 20 and pin 12 are then
ground or otherwise cut to the desired fin:Lshed dimension.
The bore 34 through pin 12 is filled with a suitable materL-
al, as grease, during the cutting operation to keep metal
particles out of the bore and bush.Lng. The grease is re-
moved after the cylinder has been cut~ As indicated in F:Lg-
ure 7, the rough radius of the cylinder is of the order of3.632" while the finished radius is of the order of 3.607".
The bushing 20 and pin 12 have initial lengths which may be
such that they extend beyond the rough surface of the cylin-
der.
