Note: Descriptions are shown in the official language in which they were submitted.
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A CARRYING SLEEVE FOR PRlN lNG AND TRANSFBR FORMS AND
A PROCESS FOR PRODUCTION OF SUCH A CARRYING SLEEVE
Techn;c~l Field
The invention relates to a metal carrying sleeve for
printing and transfer forms. The initial form of the
sleeve is a rectangular, thin-walled flat sheet, which
is shaped by bending into the desired hollow
cylindrical form, and the edges of the flat sheet
which point toward one another are connected
permanently together.
Background Art
It is known today from flexographic printing to place
sleeve-type printing and transfer forms on
galvanically-produced nickel sleeves. Printing and
transfer forms produced in this manner can be slipped
by means of pressurized air over a printing cylinder
core in the known manner and affixed thereto by
shutting off the air supply. Carrying sleeves of
fiberglass-reinforced plastic and even of carbon-
fiber-reinforced plastic are also used for this
purpose. However, it is relatively expensive to use
materials such as nickel and fiberglass-reinforced
plastic or even carbon-fiber-reinforced plastic for
producing carrying sleeves.
German Patent Application P 41 40 768 discloses a
sleeve-type offset printing form produced from a
rectangularly-cut metal plate, wherein the edges of
the plate pointing toward one another are connected by
a welded seam. The carrying sleeve produced in this
manner is coated and exposed on all sides except for
the welded seam.
DE 42 17 793 Cl discloses a sleeve-type offset rubber
blanket that is also produced from a cut base plate,
to which, while it is flat, a rubber coat is applied,
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and wherein the beginning and the end of the base
plate, along with the rubber coat, are welded
together.
Using these sleeve-type printing and transfer forms,
it is possible to print in a channel-free fashion, but
not continuously, i.e., only finite printing products
can be produced. Until now, the use of a continuous
offset printing form has not become known.
Summary of Invention
Accordingly, it is an object of the present invention
is to provide relatively economical carrying sleeves
for printing forms and transfer forms, with which
continuous printing is possible.
Pursuant to this object, and others which will become
apparent hereafter, one aspect of the present
invention resides in a metal carrying sleeve for
printing and transfer forms, the initial form of which
is a rectangular, thin-walled flat sheet. The sheet
is bent into the desired hollow cylindrical form and
the edges which point toward one another are
permanently connected together. The sleeve surface is
processed in order to form a homogeneous outer surface
so that continuous printing can be carried out. This
represents an advantageous alternative to nickel,
fiberglass-reinforced plastic and carbon-fiber-
reinforced plastic sleeves from both ecological and
economic points of view and, in addition, can be used
universally for various printing methods.
The production costs for a welded precision sleeve
processed according to the invention are many times
lower than the production costs for galvanized nickel
sleeves or coiled carrying sleeves of fiberglass-
reinforced plastic or carbon-fiber-reinforced plastic,
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especially since it is becoming increasingly difficult
to produce nickel sleeves galvanically, because this
production method is accompanied by heavy
environmental pollution.
Furthermore, in an additional embodiment of the
invention, the carrying sleeves are produced from
aluminum, steel, high-quality steel, copper or brass,
depending on the particular intended use.
In another embodiment of the invention, the entire
sleeve surface, including the connecting seam which
connects together the edges of the sheet, is
chemically roughened, anodized and provided with a
final photosensitive coat so that the entire sleeve
surface can be used for offset printing. In still a
further embodiment of the invention the entire surface
of the sleeve, including the connecting seam, is
provided with a water conducting coat. This also
permits the entire sleeve surface to be used for
offset printing.
For use in gravure printing, the entire sleeve
surface, including the coating seam, is provided with
an engraved copper coat.
In yet a further embodiment of the invention the
entire sleeve surface, including the connecting seam,
is covered with an endless rubber coat. This
arrangement is suitable for use with a transfer form.
In still another embodiment of the invention the
carrying sleeve is configured so that it can be used
directly as a carrying sleeve of a flexible printing
form for flexographic printing.
It is yet another object of the present invention to
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provide a process for producing the above discussed
carrying sleeve for printing and transfer forms.
Pursuant to this object, the inventive process
includes cutting a base plate corresponding in size to
the circumference and breadth of the printing cylinder
from thin-walled sheet metal drawn from a roll. Next
the base plate is bent into the desired cylindrical
form and the edges thereof which are directed toward
one another are connected permanently together by a
welded seam. The welding is carried out so that a
crown is created on the external surface. The entire
sleeve surface is processed in order to form a
homogeneous, continuous circumferential surface and
during this processing the crown is fit into the
homogeneous surface.
It is possible to attain the crown of the welded seam
in a number of ways. A first possibility is that
filler materials can be welded in. In another
embodiment the crown is achieved by targeted
protective gas feeds. Yet another embodiment of the
invention provides the crown by deposit welding which
follows the actual welding together of the edges of
the plate.
Pursuant to another embodiment of the inventive
process, the entire sleeve surface is processed in
order to obtain a homogeneous, continuous outer
surface. This processing includes chemically roughing
and anodizing the hollow cylindrical form of the base
plate and subsequently providing the external surface
with a photosensitive coating which creates a printing
form sleeve suitable for continuous printing. It is
desirable to use aluminum as the base plate material.
In yet a further embodiment of the inventive process a
metal coat is applied to the processed external
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surface of the hollow cylindrical form and this metal
coat is then mechanically processed. For this it is
desirable to use a copper alloy as the metal coat.
Still another embodiment of the inventive process
includes applying an endless rubber coating to the
entire processed sleeve surface.
Furthermore, it is possible to apply an endless
ceramic coat to the entire processed sleeve surface.
Brief Description of Drawings
The invention, its operating advantages, and specific
objects attained by its use will be better understood
by way of the following detailed description of
preferred embodiments with references to the appended
drawings in which:
Figure 1 is a schematic illustration of a metal
carrying sleeve pursuant to the present
invention;
Figure 2 illustrates a process of welding the tube
seam; and
Figure 3 is a cross-section through the weld seam.
Description of Preferred Embodiments
Figure 1 shows, in highly schematic fashion, an
embodiment of a carrying sleeve 1 of a metal material,
which may be aluminum, steel, high-quality steel or
brass. The initial form is a rectangular, thin-walled
flat sheet, which is bent into the desired hollow
cylindrical form. Preferably, the edges of the flat
sheet pointing toward one another are permanently
connected to one another by means of a welded seam 2.
Figure 2 shows possible ways of producing the carrying
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sleeve 1 in a quasi-continuous fashion, as is
currently known by those in the tube welding art. The
welding process itself is carried out by a laser beam.
The precision sheets of aluminum, steel, high-quality
steel, copper or brass preferably have a wall
thickness s of 0.1 to 0.6 mm. The carrying sleeves
may also be produced by means of the welding device
known from published German patent application DE
43 11 078.
The external surface of the welded carrying sleeve 1
is then processed to create a homogeneous, continuous
outer surface. To carry out this surface processing,
it is possible to use known production methods for
smoothing a metal surface, such as turning, polishing
or the like. In selecting the initial wall thickness
of the thin-walled flat sheet, it is necessary to take
into account the material that will be removed from
the external surface of the welded carrying sleeve
during processing.
As shown in Figure 3, an especially advantageous
embodiment of the welded seam provides a crown 3 on
the external surface of the sleeve 1. This crown 3 is
then processed in a subsequent process step so that a
continuous, endless outer surface is created on the
carrying sleeve surface, without any removal of
material from the precision metal sheet being
necessary or, at least, with only minimal material
removal being necessary.
The crown 3 is attained by welding filler materials,
for example, wire or powder, by targeted protective
gas feeds, or by deposit welding following the actual
welding of the plate edges.
For use in offset printing as the carrying sleeve 1
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for a printing form, the entire sleeve surface,
including the connecting seam, in the present case a
welded seam 2, is subsequently chemically roughened,
anodized and provided with a final photosensitive
coat, as is already known from the process steps
during printing plate production. In respect to
technical printing characteristics, this printing form
sleeve is identical to conventional printing plates,
except that this printing form sleeve permits
continuous printing Preferably, aluminum sheets are
used here.
However, it is also possible to apply a water-
conducting coat to an aluminum sleeve or another metal
sleeve, when the sleeve material itself is not water-
conducting but is to be made water-conducting.
Ceramic materials, for example, may be applied as
water-conducting coats by means of thermal spray
processes.
For letterpress printing, especially for flexographic
printing, the welded precision sleeve 1, the surface
of which is processed as described above, may also be
used directly as the carrier of a flexible printing
form, rubber stereo or engraved rubber printing form
and thus replace the known nickel, fiberglass-
reinforced plastic and carbon-fiber-reinforced plastic
sleeves.
For use in gravure printing, a metal coat, preferably
a copper alloy, is galvanized or sprayed all around on
the welded carrying sleeve, the surface of which has
been processed as described above, and the metal coat
itself is then engraved in a subsequent work step.
However, plastic coats may also be applied, which also
are engraved upon.
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For use in offset printing as a carrying sleeve 1 for
a transfer form, the entire processed surface of the
sleeve, including the connecting seam 2, is covered by
a continuous rubber coat, so that these rubber blanket
sleeves are identical to conventional rubber blankets
in respect to technical printing characteristicsi
however, these rubber blanket sleeves make it possible
to carry out continuous printing.
The type of rubber coat depends on the particular
printing method and is not dependent on the material
of the carrying sleeves.
The invention is not limited by the embodiments
described above which are presented as examples only
but can be modified in various ways within the scope
of protection defined by the appended patent claims.
