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Description  |
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FIELD OF THE INVENTION
The present invention is directed to a printing group of a rotary printing press. The printing group includes at least one forme cylinder and at least one transfer cylinder. These cylinders have axially extending, circumferentially spaced
surface grooves.
BACKGROUND OF THE INVENTION
An arrangement of four printing foils or formes, one behind the other in the direction of rotation of the forme cylinder, which four printing foils or formes are maintained in four pits or grooves, is known from DE 44 29 210 A1. Each of the
printing foils or formes spans a section of an arc of a circle located between two pits or grooves.
DE 44 29 891 A1 shows a printing group of a rotary printing press with a double-sized transfer cylinder; i.e. one with two section lengths over the circumference, which works together with a single-sized forme cylinder.
The arrangement of cylinders of an offset printing group is also known from DE 198 03 809 A1, wherein the circumference of the transfer cylinder is at a ratio of twice that of the forme cylinder. The forme cylinder can be occupied by one
printing forme in the circumferential direction, and in its longitudinal direction, by at least four vertical print pages in a broadsheet format, or a corresponding number of vertical or horizontal tabloid or book formats. A single slit, which is either
continuous in the longitudinal direction, or is divided in the longitudinal direction and offset by 180.degree., is arranged in the circumferential direction of the transfer cylinder for receiving two blankets, which are arranged next to each other in
the longitudinal direction of the cylinder. The blanket is designed, for example, in two layers as a rubber blanket fastened on a support plate.
Recesses in the cylinder surface of the transfer cylinder are proposed, in DE 34 41 175 C2, for the purpose of relaxing the rubber blanket. For this purpose, it is also possible to arrange a backing between the cylinder and the rubber blanket,
which backing does not extend in the circumferential direction over the entire length of the rubber blanket and has a gap. An insertion slit for receiving the discontinuous backing is arranged on the circumference of the cylinder next to the bracing
groove for the rubber blanket. The recesses arranged in the longitudinal direction of the transfer cylinder, and the groove receiving the rubber blanket, are arranged in such a way that in the contact area they respectively work together with the groove
of the plate cylinder.
DE 197 40 575 A1 shows forme and transfer cylinders, which work together, wherein the transfer cylinders in one preferred embodiment have two bracing grooves located one behind the other and two rubber blankets maintained in the bracing grooves.
In another example, a double-sized transfer cylinder acts together with a double-sized forme cylinder wherein, however, both cylinders have only one bracing groove in the circumferential direction. In all of these examples, the grooves do not roll off
on each other.
A single forme cylinder is known from DE-OS 19 60 635, which, in the circumferential direction, has several grooves for fastening printing formes on its circumference. At least one of the grooves can be covered when placing a printing forme on
the forme cylinder in the circumferential direction.
SUMMARY OF THE INVENTION
The object of the present invention is based on providing a printing group of a rotary printing press.
In accordance with the present invention, this object is attained by providing a printing group of a rotary printing press with at least one transfer cylinder and at least one forme cylinder. The transfer cylinder has at least one blanket edge
receiving groove. The forme cylinder has at least two axially extending, circumferentially spaced grooves. At least one of the forme cylinder grooves is at least partially covered by a printing forme during press operation. This partially covered
groove rolls off a groove in the cooperating transfer cylinder.
The advantages to be obtained by the present invention lie, in particular, in that a flexible employment of several dressing or covering formats is possible. When using dressings or coverings of large circumferential lengths, a pressure relief
in the areas of grooves, in particular in the area of grooves covered by dressings, is assured at the same time, as well as the highest possible print quality in the course of unwinding or forming the printed image.
The arrangement of several grooves, each extending in the longitudinal or axial direction of the forme and/or transfer cylinder, meets the most diverse conditions as required. It is thus not necessary to exchange the cylinder in case of varying
demands made on existing printing presses, or to consider every demanded profile individually during the manufacturing process.
It is particularly advantageous, in accordance with the present invention, that it is possible to take into consideration different formats of the dressings or coverings in the circumferential and longitudinal direction, as well as different
groupings and phase shifts of the cylinders which work together in a reciprocal manner. In this way these formats can be optimized in respect to the demands, some of which are in conflict with each other, regarding maintaining the registration, low
vibration, arrangement of the printing areas rolling off on each other, and minimizing paper which cannot be imprinted.
A preferred embodiment of a forme cylinder with double circumference, i.e. for example two newspaper pages in the circumferential direction, allows the selective placement of printing formes arranged one behind the other in the circumferential
direction, or of printing formes extending over the entire circumference, in which case a groove is covered. The arrangement of printing formes extending over the full circumference considerably reduces the change-over time, for example. In case of a
transfer cylinder, an arrangement of blankets extending over the full circumference considerably reduces the change-over time.
By arranging at least two grooves, which are almost continuous in the longitudinal direction, on a transfer cylinder, a multitude of options for arranging dressings or coverings, for example blankets, is created. With the arrangement of several
grooves, it is also advantageous, in view of the quality of the unwinding or rolling-off of the printed image, in comparison with cylinders of twice the size but with only one groove, that a covered groove can simultaneously be used for relaxing the
dressing or covering in the case of blankets extending over the entire circumference.
The arrangement of a single dressing or covering extending in the longitudinal and circumferential direction results in advantages regarding the multitude of printable formats, such as height and width of the printed areas, for example in the
situation of a panorama.
When covering a groove by a printing forme, it is advantageous, for reasons of the danger of a break, to arrange the forme cylinder and transfer cylinder in such a way that the covered groove of the forme cylinder rolls off on a groove of the
transfer cylinder. The roll-off of a groove of the transfer cylinder, covered by a blanket, on a groove of the forme cylinder is also advantageous in view of a further improved relaxation of the blanket in the course of the passage of the grooves over
each other, and therefore for the rolled-off or formed printed image.
The arrangement of several dressings or coverings, which are arranged next to each other in the longitudinal direction of the cylinder, and each of which extends almost over the entire circumference, has advantages, for example, in view of their
handling and individual replacement capability. This applies, in particular, for long cylinders, such as is the case for double-width, for example, four newspaper pages in the longitudinal direction of the cylinder or even triple-width, for example six
newspaper pages cylinders.
Regarding the quality of unwinding or rolling-off of the printed image, the embodiment of the dressings for the transfer cylinder is also advantageous in the form of multi-layered or multi-ply blanket, which has a support plate and a cover, or
layer, connected with the latter. With large dimensions in particular, an embodiment, which is as dimensionally stable as possible, is essential for a consistently good and exactly registered printing quality over the circumference of the cylinder.
An embodiment of the grooves with a narrow opening toward the outer or shell surface of the cylinder is also advantageous, for example, in view of reducing paper consumption. A narrow opening is particularly advantageous for grooves in the forme
cylinder, in particular for grooves which are at least partially covered. For example, it is possible because of this to further reduce the breaking danger.
It is moreover advantageous to make the circumferential ratio of the transfer cylinder in respect to the forme cylinder as a whole number and to arrange the grooves symmetrically in the circumferential direction on the cylinder.
BRIEF
DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the present invention are represented in the drawings and will be described in greater detail in what follows.
Shown are in:
FIG. 1, a schematic perspective view of a pair of double-width cylinders, in which the forme cylinder has two grooves extending in the longitudinal direction, and the dressings or coverings extend over almost the complete circumference of the
forme cylinder,
FIG. 2, a pair of double-width cylinders, in which the forme and the transfer cylinders are each formed with two grooves extending in the longitudinal direction, and the dressings or coverings extend over almost the complete circumference of the
forme and transfer cylinder,
FIG. 3, two pairs of double-width cylinders, in which the transfer cylinder in each pair is formed with two grooves extending in the longitudinal direction and is equipped with two dressings or coverings extending over almost the entire
circumference, which coverings are located next to each other in the longitudinal direction,
FIG. 4, two pairs of double-width cylinders, in which the transfer cylinder in each pair is formed with two grooves extending in the longitudinal direction and is equipped with two dressings or coverings extending over almost the entire
circumference, which are located next to each other in the longitudinal direction, but are offset by 180.degree. in the circumferential direction,
FIG. 5, two pairs of double-width cylinders, in which the transfer cylinder in each pair is formed with two grooves extending in the longitudinal direction and is equipped with two dressings or coverings extending over almost the entire length of
the barrel, which are located one behind the other in the circumferential direction,
FIG. 6, two pairs of double-width cylinders, in which the transfer cylinder in each pair is formed with two grooves extending in the longitudinal direction and has four dressings, wherein respectively two dressings or coverings arranged one
behind the other in the circumferential direction are arranged next to each other in the longitudinal direction,
FIG. 7, two pairs of double-width cylinders, in which the transfer cylinder in each pair is formed with four grooves, each extending in the longitudinal direction, and is equipped with two dressings or coverings extending over almost the entire
length of the barrel, which are located one behind the other in the circumferential direction, in
FIG. 8, a multi-layer blanket with a groove and holding device, in
FIG. 9, a pair of triple-width cylinders with a cooperating counter-pressure cylinder in which the forme cylinder is formed with two grooves extending in the longitudinal direction and the transfer cylinder has three blankets offset from each
other in the axial direction; and in
FIG. 10, two pairs of triple-width cylinders in which the transfer cylinder in each pair is formed with two grooves extending in the longitudinal direction and is equipped with one dressing or covering extending over almost the entire
circumference and in which each forme cylinder has two grooves extending in the longitudinal direction over the length of the forme cylinder which is six newspaper pages in width and has a circumferential length of two upright newspapers pages.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A printing group of a rotary printing press is shown in FIG. 1 and has at least one cylinder pair 01, consisting of two cylinder 02, 03, for example a transfer cylinder 02 and a forme cylinder 03 acting together with it. Via the material 04 to
be imprinted, which material 04 can be seen in FIG. 3 and FIG. 9 for example, the transfer cylinder 02 can act together with a counter-pressure cylinder, which is represented in FIG. 9 at 40, or with a transfer cylinder 07, also as seen in FIG. 3, to
which a forme cylinder 08, of a second cylinder pair 06, is assigned. The transfer cylinders 02, 07 can each be equipped with at least one dressing or covering 09, for example a blanket 09, and the forme cylinders 03, 08 each can also be equipped with
at least one dressing or covering 11, for example a printing forme 11.
Depending on the demands made on the printing formats and the printing output, as well as various possibilities regarding the paper guidance, the cylinder pairs 01, 06 of FIGS. 1, 2, 9 and FIGS. 3, 7 and 10, respectively are embodied to be of
various widths. For example, the cylinder pairs 01, 06 for printing newspapers can be of single, double or triple width, wherein single width identifies the width of the barrel, for example that of the forme cylinder 03, for two vertical or horizontal
newspaper pages. In connection with job printing, double width identifies the width required for four horizontal or six vertical A4 pages. The circumferences of the transfer cylinders 02, 07 and of the forme cylinders 03, 08, are respectively of single
or double length or height in relation to the most varied vertical or horizontal formats, for example a vertical or a horizontal newspaper format. Advantageous groupings in connection with newspaper printing are, for example, a double length
circumference, i.e. two pages in the circumferential direction, of the transfer cylinder 02, 07, acting together with a double or single circumference of the forme cylinder 03, 08, each of double width. A triple width format is shown in FIG. 9 in which
the cylinder pair 01 are used for printing newspapers of six newspaper pages in width. The two cylinders both have a double circumference.
FIG. 1 shows a double-width cylinder pair 01, wherein the transfer cylinder 02 and the forme cylinder 03 each also have a double circumference. The forme cylinder 03 has two grooves 12, 13, each extending in the longitudinal direction and spaced
apart from each other in the circumferential direction of the forme cylinder 03. Each groove 12, 13 is provided for receiving the ends of at least one printing forme 11. The transfer cylinder 02 has a groove 14 for receiving the ends of at least one
blanket 09. The grooves 12, 13 of the forme cylinder 03, 08 are arranged, at least over a partial section of the forme cylinder in the longitudinal direction of the forme cylinder 03, 08, spaced from each other in the circumferential direction, viewed
in a cross section extending perpendicular in respect to the axis of rotation. In the configuration shown in FIG. 1, the forme cylinder 03 is equipped with four printing formes 11, for example printing plates 11, arranged next to each other in the
longitudinal direction of the cylinder, whose respective two ends are maintained in the groove 12. Each printing forme 11 extends over the entire circumference of cylinder 03, except for the area of the groove 12, and each forme 11 is covering over the
groove 13. To prevent the danger of breaking, in an advantageous manner the forme cylinder 03 and the transfer cylinder 02 are arranged with respect to each other in such a way that, in the course of rolling off of the transfer cylinder 02 and the forme
cylinder 03 with respect to each other, the covered groove 13 of the printing forme 03 acts together with the groove 14 of the transfer cylinder 02. The latter is not necessary if, for example, the groove 13 can be closed off by, for example, a
releasable cover, or if the groove width is so small that a break is avoided. The forme cylinder 03 can be embodied to be of single, double or triple width. A double width is shown in FIG. 1 while a triple width is shown in FIG. 9. It can be flexibly
covered in various ways, for example with one continuous, or with two or more printing plates 11 of the most varied formats, for example single or panorama, arranged next to each other in the longitudinal direction, if needed, the forme cylinder 03 can
also have more than two grooves 12, 13, which extend in the longitudinal direction and which are spaced apart in the circumferential direction. The transfer cylinder 02 in FIG. 1 can have a sole continuous groove 14, in which two blankets 09 are held
next to each other in the axial direction. It is also possible to arrange two grooves 14, 16, which are next to each other in the axial direction, but which are circumferentially offset in respect to each other, for example by 180.degree.. This
arrangement of the transfer cylinder is shown in FIG. 9. The blankets arranged next to each other on cylinder 02 are also offset in respect to each other in this arrangement, which is represented in FIG. 9, so that the second, axially offset groove 14
would be covered in FIG. 9 and would not be visible.
The transfer cylinder 02 can also have a second groove 16 which, for example, lies diametrically opposite the first transfer cylinder groove 14 and which extends in the longitudinal direction of the transfer cylinder 02, as represented by way of
example in FIG. 2. The grooves 14, 16 of the transfer cylinder 02 or 07 are arranged, at least over a partial section in the longitudinal direction of the transfer cylinder 02 or 07, behind each other in the circumferential direction, viewed in a cross
section extending perpendicular in respect to the axis of rotation. In the example depicted in FIG. 2, a single blanket 09, which extends, as far as the area of the groove 14, over the entire length of the barrel of transfer cylinder 02 and over almost
the entire circumference, covers the transfer cylinder 02. By way of example, the forme cylinder 03 in FIG. 2 is covered by two printing plates 11, which lie next to each other in the longitudinal direction of the forme cylinder 03 and each of which
extends over almost the entire circumference of cylinder 03. In the example, the covered groove 16 acts together with the also covered groove 13 of the forme cylinder 03. But, as in the first preferred embodiment, it can also roll off on the uncovered
groove 14.
Besides the double-width embodiment, represented in FIGS. 1, 2 and 3 of the transfer cylinder 02 or 07, which acts together with the forme cylinder 03, 08, it can also be embodied at a single or triple width, for example. The transfer cylinder
02, 07 in the first two embodiments of FIGS. 1, 2, and 3, which acts together with the forme cylinder 03, 08 having two grooves 12, 13, can, as shown in FIGS. 1 to 7 and their description, by way of example, be equipped flexibly with one continuous
blanket 09, with two or more blankets 09, arranged next to each other in the longitudinal direction, or arranged behind each other in the circumferential direction, or with several blankets 09, arranged next to each other in the longitudinal direction
and simultaneously with several blankets 09 arranged behind each other in the circumferential direction. In this case, a forme cylinder 03 of double circumference, for example, from FIGS. 1 and 2 and their description, can take the place of the single
circumference forme cylinders 03, 08 represented in FIG | | |
