Printing cylinder

A printing cylinder is disclosed which makes it possible to remove the ink adhering to the side surfaces of the printing cylinder after the printing has been finished without the need of moving the printing cylinder.

BACKGROUND OF THE INVENTION 
A printing method has been put into practice in which a printing ink is fed 
onto the printing face constituted by the outer surface of a printing 
cylinder of a cylindrical shape (hereinafter simply referred to as 
printing cylinder), the printing cylinder is set to a printing press and 
is rotated in order to print the papers, as is done, for example, in 
gravure printing. 
In the above-mentioned printing method using the printing cylinder, the ink 
adhering to the printing face of the printing cylinder is wiped off after 
the printing is finished. The ink layer adhering to the side surfaces of 
the printing cylinder usually becomes as thick as ten and several 
millimeters at a moment when the printing is finished. The ink adhering to 
the side surfaces of the printing cylinder cannot be automatically removed 
because the printing cylinder is heavy and that the ink is not adhered 
uniformly. If the ink that is adhered is not wiped off, then it mixes into 
the ink used in the next printing, causing the ink to lose its color tone. 
Furthermore, the ink that is coagulated peels off at the time of printing 
and adheres to the surface of the printing cylinder causing the doctor 
blade to be damaged and hindering the printing. 
In order to solve the problem caused by the ink that is adhered to the side 
surfaces of the printing cylinder, a method has been disclosed in Japanese 
Laid-Open Patent Publication No. 91281/1987 in which the printing cylinder 
is removed from the printing press and the side surfaces thereof are 
cleaned. That is, the printing cylinder having ink adhered to the side 
surfaces thereof is removed from the printing press, and the water is 
sprayed under very high pressure against the printing cylinder. 
According to the above method, however, it is necessary to clean the side 
surfaces of the printing cylinder in addition to the operation for wiping 
the ink off the printing face of the printing cylinder that is removed 
from the printing press; i.e., a great deal of labor is required to move 
the very heavy printing cylinder to the cleaning device which sprays water 
under a very high pressure. Moreover, there is a likelihood of damaging 
the printing face of the printing cylinder while it is being moved or 
during the operation for washing out the ink. 
Japanese Utility Model Laid-Open Publication No. 93236/1986 proposes a 
printing cylinder which prevents the ink from adhering onto the side 
surfaces by providing the side surfaces of the printing cylinder with a 
layer of a fluorine-resin such as polytetrafluoroethylene. This makes it 
possible to considerably reduce the amount of ink adhering to the side 
surfaces of the printing cylinder making, however, it necessary to remove 
the ink adhered to the side surfaces in addition to the operation for 
wiping the ink off the printing face of the printing cylinder. Like the 
above-mentioned method, therefore, it is necessary to clean the side 
surfaces of the printing cylinder leaving such problems as the 
introduction of a cleaning step and the likelihood of damaging the 
printing cylinder while it is being moved for the purpose of being 
cleaned. 
OBJECTS OF THE INVENTION 
The object of the present invention is to provide a printing cylinder which 
makes it possible to remove the ink adhered to the side surfaces of the 
printing cylinder after the printing has been finished without the need of 
moving the printing cylinder. 
Another object of the present invention is to provide a printing cylinder 
which makes it possible to efficiently clean the side surfaces thereof 
even under the condition where the printing cylinder is being mounted on 
the printing press. 
SUMMARY OF THE INVENTION 
The above objects of the present invention are accomplished by removable 
annular side plates which are attached to the side surfaces of the body of 
the printing cylinder utilizing magnetic force. The annular side plates 
have a circumference close to the circumference of the side surfaces of 
the body of the printing cylinder. 
The present invention will now be described in further detail in 
conjunction with the drawing that illustrate preferred embodiments of the 
printing cylinder constituted according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The structure of the body of the printing cylinder of the present invention 
will now be described in conjunction with FIG. 1. In the present 
invention, a widely known structure comprising a cylindrical drum 
constituting the printing face and members constituting side surfaces 3, 
is employed as a body 1 of the printing cylinder 19 without any particular 
limitation. There is no particular limitation with regard to the 
materials, either. Widely known materials such as steel, an aluminum 
alloy, etc., are generally used. drum and the side surfaces of the body of 
the printing cylinder 19 may be made of the same material or different 
material. for example, the whole printing cylinder 19 may be made of a 
steel or the drum of the printing cylinder 19 may be made of an aluminum 
alloy and the side surfaces may be made of steel. Furthermore, the body 1 
of the printing cylinder 19 has a mechanism at the center of both side 
surfaces thereof that couples to the rotary shaft of a printing press. For 
instance, the rotary shaft of the printing press ma be secured to the 
centers of side surfaces 3 of the body 1 of the printing cylinder 19 as a 
unitary structure. Alternatively, bores for fixing the rotary shaft may be 
formed at the centers of the side surfaces 3, without any particular 
limitation. The embodiment shown in FIG. 1 deals with the structure in 
which bores are formed to fix the rotary shaft. In this case, it is 
desired to provide the bore with a cylindrical cone 9 which spreads 
outwardly to facilitate the mounting of the rotary shaft on the printing 
press. 
When the side surfaces 3 are not made of a ferromagnetic substance such as 
steel, the side surfaces 3 are provided with a layer of a ferromagnetic 
substance or with a layer which serves as a permanent magnet, using a 
fixing means such as screws or the like. 
Depending upon the mode of printing, furthermore, there is formed a 
metal-plated layer or a rubber layer for forming a printing plate on the 
drum of the body 1 of the printing cylinder 19. 
According to the present invention, removable annular side plates 2 are 
attached to both side surfaces 3 of the printing cylinder 19 utilizing the 
magnetic force to cover the side surfaces. There is no particular 
limitation to the size of the annular side plates 2 provided they have an 
outer diameter D2 which is close to the outer diameter D1 of the body 1 of 
the printing cylinder 19. In general, the outer diameter D2 of the annular 
side plates 2 should desirably lie over a range from the outer diameter D1 
of side surfaces 3 of the body 1 of the printing cylinder 19 to a diameter 
which is smaller by 20 mm than the outer diameter D1. In the case of the 
structure in which the rotary shaft is fixed to the printing cylinder 19, 
the bore diameter D3 of the annular side plates 2 should be smaller than 
the outer diameter D2 of the side plates 2 but should be greater than the 
outer diameter of the rotary shaft. In the case of the structure where 
bores are provided to insert the rotary shaft in the printing cylinder 19 
as shown in FIG. 1, the bore diameter D3 should be smaller than the outer 
diameter of the side plates 2. When the bore is provided with the cone 9 
to receive the rotary shaft, furthermore, the bore diameter D3 of the 
annular side plates 2 should be greater than the outer diameter of the 
cone 9. The annular side plates 2 should desirably be so designed as to 
partly cover the outer circumferential portion of the side surfaces 3 as 
shown in FIG. 1 from the standpoint of facilitating the operation for 
attaching and detaching the annular side plates 2, reducing the weight, 
and enhancing the effect of preventing the ink from adhering onto the side 
surfaces 3 of the body 1 of the printing cylinder 19 despite an increase, 
in the areas that are covered. It is preferable that difference between 
the outer diameter D2 of the annular side plates 2 thereof and the bore 
diameter D3 thereof is from 10 to 60% with respect to the outer diameter 
D1 of the printing cylinder 19. 
It is further desired that the annular side plates 2 have a small thickness 
to reduce the weight thereof. However, too small a thickness is 
accompanied by a reduction in the mechanical strength which may result in 
the breakage when the annular side plates 2 are being attached to or 
detached from the side surfaces 3 of the body 1 of the printing cylinder. 
Therefore, a suitable thickness should be determined by taking the 
reduction in weight and the mechanical strength into consideration. 
Usually, the thickness ranges from 0.5 to 10 mm. 
As shown in FIG. 1-A, the annular side plates 2 may have a tapered outer 
surface whose thickness increases from the outer circumference toward the 
inner circumference. 
There is no particular limitation in the embodiment of detachably attaching 
the annular side plates 2 to the side surfaces 3 of the printing cylinder 
19 by utilizing a magnetic force provided the side plates 3 can be held on 
the side surfaces 2 of the printing cylinder 19 by the magnetic force. In 
general, the side surfaces 3 of the body 1 of the printing cylinder 19 are 
made from a ferromagnetic substance and the annular side plates 2 are 
partly or entirely made from by a permanent magnet, or, alternatively, the 
side surfaces 3 of the body 1 of the printing cylinder 19 are made from a 
permanent magnet and the annular side plates 2 are partly or entirely made 
from a ferromagnetic substance. 
Any widely known material can be used as the ferromagnetic material without 
any particular limitation, provided it is magnetized and is attracted by 
the magnetic field of a permanent magnet. Examples include such metals as 
iron, cobalt, nickel, etc. Moreover, any permanent magnet may be used 
without any particular limitation. Examples include carbon steel, tungsten 
steel, KS-steel, Alnico, etc. The above ferromagnetic substance and 
permanent magnet may be used in their own form or may be used in the form 
of a so-called "plastic magnet" by pulverizing them and mixing them in a 
matrix of a resin or a rubber. 
The side plates 2 which are held on the side surfaces 3 of the printing 
cylinder 19 by the magnetic force may begin to be deviated from the side 
surfaces 3 if they are too heavy due to the centrifugal force produced 
during the printing operation by the rotation of the printing cylinder 19. 
According to the present invention therefore, though the annular side 
plates 2 can be made entirely of a permanent magnet (including plastic 
magnet) or comprised of a the ferromagnetic substance, it is desired to 
partly use the permanent magnet or the ferromagnetic substance depending 
upon the intensity of magnetic force of the permanent magnet with a light 
material such as a thermoplastic resin, e.g., polyolefin resin, polyvinyl 
chloride resin or the like resin, in order to reduce the weight of the 
side plates 2 covering the side surfaces 3 of the printing cylinder 19. 
FIG. 5 is a sectional view illustrating the internal structure of the 
annular side plate 2 which partly employs the permanent magnet according 
to a representative embodiment. In FIG. 5, the side plate 2 is formed in 
an annular shape and has a thermoplastic resin film 8 laminated on one 
surface of the permanent magnet 6 (inclusive of a plastic magnet) and a 
thermoplastic resin 7 molded on the other surface thereof. According to 
this embodiment, the thermoplastic resin film 8 having a small thickness 
is formed on one side of the permanent magnet 6. Therefore, if the side of 
the magnet 6 in contact with the resin film 8 is facing is the side 
surface 3 of the printing cylinder, the magnetic force of the side plate 2 
is not lost with respect to the above side. 
The present invention also provides a printing cylinder 19 employing the 
above-mentioned annular side plates 2 capable of being opened and attached 
to or detached from the body of the printing cylinder when the body of the 
printing cylinder is mounted on the printing press. The annular side plate 
shown in FIG. 1 is continuous throughout the whole circumference and must 
be attached thereto or detached therefrom by removing the printing 
cylinder from the printing press. On the other hand, the annular side 
plates in the present invention are capable of being opened to attach to 
and detach from the printing cylinder by opening them when the printing 
cylinder 19 is mounted on the printing press, making it possible to carry 
out the operation more efficiently. 
The annular side plate can be formed in a manner to be split or cut at only 
one section so that it can be opened. As shown in FIGS. 4, 4-A and 4-B, 
the annular side plate 2 can be split into two or ore segments. 
As shown in FIGS. 4-C and 4-D, furthermore, the annular side plate 2 can be 
opened by cutting only one portion thereof, provided it has flexibility. 
In order to prevent the ink adhered to the side surfaces of the body 1 of 
the printing cylinder from moving in the direction of the rotary shaft 
according to the present invention as shown in FIG. 2, it is desired to 
provide a continuous protrusion 4 along the inner circumference on the 
surface of the annular side plate 2 opposite to the surface that comes in 
contact with the side surface of the printing cylinder 19. Though there is 
no particular limitation, the protrusion usually has a height of about 2 
to 50 mm. 
According to the present invention as shown in FIG. 3 or 4, furthermore, it 
is desired to provide a flange 5 along the outer circumference of the 
protrusion 4 in order to further increase the effect of the protrusion 4 
that is shown in FIG. 2. The flange usually has a width of from 1 mm to 
several mm. 
According to the embodiment in which the protrusion is provided along the 
inner circumference of the side plate as shown in FIGS. 2 to 4, it is 
desirable to decrease the width of the annular side plate 2 and to reduce 
the weight thereof. 
According to the present invention, it is desired that the annular side 
plate 2 has at least the surface thereof composed of a material on which 
the ink adheres sparingly. Examples of such a material include polyamide, 
polypropylene, polyethylene, fluorine-resin, silicone resin, and like 
resins. 
The printing cylinder 19 of the present invention is mounted on the 
printing press by a known method without any particular limitation. For 
instance, the body 1 of the printing cylinder 19 having a rotary shaft 
fixed thereto is used with its rotary shaft being held by the bearings of 
the rotary device of he printing press. The body 1 of the printing 
cylinder 19 having bores for fixing the rotary shaft thereto is used with 
its rotary shaft fixed to the bores and held by the bearings of the rotary 
device of the printing press. Or, the printing cylinder 19 is used by 
pressing the rotary shaft interlocked to the rotary device to the cones 9 
fitted to the bores on both sides of the printing cylinder 19. 
FIG. 6 is a perspective view illustrating the major structure of the 
printing unit of a gravure printing press wherein a rotary shaft 10 
interlocked to the rotary device is pressed by a fastening device 11 onto 
the cones 9 fitted to the bores on both sides of the printing cylinder 19 
of the embodiment shown in FIG. 1 thereby to fix the printing cylinder. In 
FIG. 6, reference numeral 12 denotes an ink pan, 13 denotes an applicator, 
14 denotes a doctor blade, 15 denotes a back-up roller, 16 denotes an ink 
tank, 17 denotes an ink feeding pump, and reference numeral 18 denotes an 
ink feeding pipe. 
According to the present invention, usually, the printing cylinder 19 is 
removed from the printing press after the printing is finished, and the 
annular side plates 2 are replaced before or after the ink is wiped off 
the printing face. Alternatively, the annular side plates 2 of the 
structure capable of being opened can be replaced by the new ones without 
the need of removing the printing cylinder 19 from the printing press. 
The used side plates 2 may be discarded away but are usually cleaned and 
used again for the printing cylinder 19. 
The above side plates 2 can be easily cleaned compared with the case of 
directly cleaning the side surfaces 3 of the printing cylinder 19 because 
there is no need to remove the printing cylinder 19. Furthermore, it is 
more difficult to automatically clean the side surfaces 3 of the printing 
cylinder 19. However, the annular side plates 2 which have been removed 
from the side surfaces 3 of the printing cylinder 19 can be cleaned in the 
cleaning tank easily and automatically. 
The printing cylinder 19 of the present invention can be adapted not only 
to the gravure printing press but also to any other widely known printing 
presses that use the printing cylinder. 
According to the printing cylinder of the present invention, the annular 
side plates 2 are detachably attached to the body 1 of the printing 
cylinder 19 utilizing a magnetic force. Therefore, the side plates 2 can 
be easily attached utilizing the magnetic force prior to the printing 
operation and can be easily detached after the printing operation is 
finished while the ink is being wiped off the printing face. Moreover, the 
side surfaces 3 of the printing cylinder 19 have been covered with the 
annular side plates 2 during the printing operation and need not be 
cleaned after the side plates are taken out; i.e., attaching the new 
annular side plates is all that it takes to prepare the printing cylinder 
of the present invention again for use in the printing operation. 
Therefore, no operation, is required for moving the printing cylinder 19 
through other processing steps for removing the ink adhered on the side 
surfaces 3, and there arises no problem of damaging to the printing 
cylinder. Moreover, the time for removing the ink adhered on the side 
surfaces can be shortened by more than 90% compared with the conventional 
method of removing the ink adhering on the side surfaces 3 by cleaning 
after the ink has been wiped off the printing cylinder. 
In particular, the annular side plates 2 capable of being opened, i.e., the 
annular side plates 2 split into a plurality of segments or having 
flexibility and cut at one portion, can be replaced without the need of 
removing the printing cylinder 19 from the printing press to further 
enhance the above-mentioned effects. 
The annular side plates 2 detached from the side surfaces 3 of the printing 
cylinder can be cleaned for being used repetitively, i.e., can be cleaned 
in a step separate from the printing step. A known automatic cleaning 
system can be employed for for greater. 
EXAMPLES 
EXAMPLE 1 
The printing cylinder shown in FIG. 3 was constructed. Annular side plates 
made of a plastic magnet having an outer diameter D2 of 290 mm, a bore 
diameter D3 of 190 mm, a protrusion with a height of 30 mm, and a flange 
with a width of 20 mm and a thickness of 3 mm, were magnetically attached 
to both side surfaces of a body of the printing cylinder made of a steel 
having an outer diameter D1 of 290 mm. 
The printing cylinder was mounted on a gravure printing press shown in FIG. 
6, and the printing was carried out under the following conditions. 
______________________________________ 
Line speed 200 mm/min. 
Number of revolutions of 
219.6 rpm 
the printing cylinder 
Printing time 30 min. 
Type of ink rubber-type ink for 
gravure printing 
______________________________________ 
The annular side plates practically did not deviate from the body of the 
printing cylinder during the printing operation. 
After the printing operation, the printing cylinder was removed from the 
printing press, and the annular side plates were detached from the body of 
the printing press, and the annular side plates were detached from the 
body of the printing cylinder with ease. The ink did not adhere at all to 
the side surfaces of the main body of the printing cylinder or to the 
rotary shaft. 
The ink was wiped off the printing face, and the new annular side plates 
were attached to the side surfaces of the body of the printing cylinder 
which was then mounted on the printing press in order to carry out the 
printing in the same manner as described above. 
The annular side plates detached from the printing cylinder were dipped in 
methylene chloride. The adhered ink was completely removed, and the 
annular side plates could be used again. 
The aforementioned attachment of the annular side plates to the body of the 
printing cylinder, printing operation, wiping of the ink, detachment of 
the annular side plates, and cleaning operation, were repeated 50 times by 
changing the ink color each time. However, there was no reduction in the 
magnetic force of the annular side plates and no discoloration, either, 
due to inks used before and after the printing. 
EXAMPLE 2 
The annular side plates were attached to the body of the printing cylinder, 
the printing as carried out, the ink was wiped off, the annular side 
plates were detached, and the cleaning operation was carried out in the 
same manner as in the example 1 with the exception of using annular side 
plates having an outer diameter D2 of 290 mm, a bore diameter D3 of 190 mm 
and a thickness of 3.3 mm. The side plates possessed the internal 
structure shown in FIG. 5. That is, the plastic magnet having a width of 
35 mm and a thickness of 2.1 mm was held between a polypropylene film 
having a thickness of 100 um and a polypropylene resin mold. 
The annular side plates practically did not deviate from the body of the 
printing cylinder during the printing operation. 
After the printing operation, the printing cylinder was removed from the 
printing press, and the annular side plates 2 were detached from the body 
1 of the printing cylinder with ease. The ink did not adhere at all the 
side surfaces of the main body of the printing cylinder or to the rotary 
shaft. 
The annular side plates detached from the printing cylinder were dipped in 
methylene chloride. The adhered ink was completely removed, and the 
annular side plates could be used again. 
Even after the experiment, there was no reduction in the magnetic force of 
the annular side plates and no discoloration, either, due to inks used 
before and after the printing. 
EXAMPLE 3 
The printing was carried out using the same printing press as that of the 
example 2 but changing the annular side plates 2 into those having an 
outer diameter D2 of 290 mm, a bore diameter D3 of 190 mm and a thickness 
of 3.3 mm, and having a cut at one portion thereof as shown in FIG. 1. The 
side plates possessed the internal structure as shown in FIG. 5. That is, 
a plastic magnet having a width of 35 mm and a thickness of 2.1 mm was 
held between the polypropylene film 8 having a thickness of 100 um and a 
polypropylene resin mold. 
The body of the printing cylinder was mounted on the gravure printing press 
shown in FIG. 6, and the annular side plates 2 were fitted through their 
cut portions to the rotary shaft and were magnetically attached to the 
side surfaces of the body of the printing cylinder. 
The annular side plates practically did not deviate from the body of the 
printing cylinder during the printing operation. 
After the printing operation, the annular side plates 2 could be detached 
from the body 1 of the printing cylinder without the need of removing the 
printing cylinder from the printing press. The ink did not adhere at all 
to the side surfaces of the body of the printing cylinder or to the rotary 
shaft. 
The ink could be wiped off the printing face and the new annular side 
plates could be attached under the condition where the body of the 
printing cylinder was being mounted on the printing press. 
The annular side plates detached from the printing cylinder were dipped in 
methylene chloride. The adhered ink was completely removed, and the 
annular side plates could be used again. 
The aforementioned attachment of the annular side plates to the body of the 
printing cylinder, printing operation, wiping of the ink, detachment of 
the annular side plates and cleaning operation, was repeated 50 times by 
changing the ink color each time. However, there was no reduction in the 
magnetic force of the annular side plates and no discoloration, either, 
due to inks used before and after the printing. 
EXAMPLE 4 
The procedure was carried out in the same manner as in the example 3 but 
using the annular side plates that are split into two as shown in FIG. 4 
instead of the annular side plates used in example 1. 
The annular side plates practically did not deviate from the body of the 
printing cylinder during the printing operation. 
The annular side plates could be attached to and detached from the body of 
the printing cylinder without the need of removing the body of the 
printing cylinder from the printing press. The ink did not adhere at all 
to the side surfaces or the main body of the printing cylinder or to the 
rotary shaft. 
The annular side plates detached from the printing cylinder were dipped in 
methylene chloride. The adhered ink was completely removed, and the 
annular side plates could be used again. 
The aforementioned attachment of the annular side plates to the body of the 
printing cylinder, printing operation, wiping of the ink, detachment of 
the annular side plates and cleaning operation, was repeated 50 times by 
changing the ink color each time. However, there was no reduction in the 
magnetic force of the annular side plates and no discoloration, either, 
due to inks used before and after the printing.