Printing – Print plate feeding or delivering
Reexamination Certificate
2000-02-10
2002-08-27
Evanisko, Leslie J. (Department: 2854)
Printing
Print plate feeding or delivering
C101S479000, C101S480000, C101S415100
Reexamination Certificate
active
06439118
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method and a device for making-ready and feeding printing forms to a form cylinder of a printing machine, at least one printing form being made-ready or provided in a container in a rolled-up state and being unrolled to be fed to the form cylinder.
A method and a device of this type are disclosed in the published German Patent Document DE 43 03 872 C2. In that document, a relatively thin printing film is rolled up in a storage container, the latter is inserted into the form cylinder and the printing film is guided around the form cylinder. The end of the printing film projects into a receiving container, so that the printing film, like the film of a camera, can be conveyed onward from the storage container to the receiving container after each print job has been completed, in such a way that a new printing form rests on the form cylinder. However, a precondition for such a method and such a device is that the printing film or the printing plates likewise proposed are present as a film-like strip which is so flexible that it can be drawn around the form cylinder.
Printing plates provided for high-quality printing, however, even if they are plastic printing plates, have an excessively great stiffness or inflexibility, especially when they are intended to be used for a large print edition or to be reused. Drawing the printing film around the form cylinder, moreover, is a problem even in the case of thin, flexible printing forms. For this reason, an air cushion for this process is proposed by the cited document. Further disadvantages of this heretofore known proposal are that the operations during the application and renewal of the printing film require intensive work and lengthen the machine down or stoppage times, considerable space in the form cylinder is required in order to accommodate two rolls, the accommodation of two rolls restricts the number of jobs which can be processed without interruption, and the mass of the two rolls leads to imbalance problems. In addition, using the thin printing film and the receiver contemplated therefor, the achievement of high register accuracy for multicolor printing is not possible, because the thin printing film is deformed under the effect of force applications.
A further proposal for making-ready and feeding printing forms to a form cylinder is disclosed in the published German Patent Document DE 196 23 694 A1. Described therein is a cartridge for accommodating printing forms, which are stored flat therein. Although “printing films” are mentioned as printing forms in this document, it has transpired that flat storage of printing forms in a cartridge requires such a great stiffness of the printing forms that only metal printing plates can generally be used. Flexible printing plates, mostly plastic printing plates, such as polyester plates, which are already too stiff for the first-mentioned method and device, are not stiff enough to be stored in the cartridge. They sag and are difficult to guide. As a result, problems occur during the automatic feeding of printing plates to the plate cylinder, and during tautening or clamping on the latter.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method and a device of the type referred to in the introduction hereto wherein flexible printing plates for high-quality printing and large editions can be made-ready on the printing machine during machine operation, and simple and reliable feeding and tautening or clamping of the printing plates on the plate cylinder is possible.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a method of making-ready and feeding printing forms to a form cylinder of a printing machine, wherein at least one printing form is provided in a rolled-up state in a container and is unrolled so as to be fed to the form cylinder, which comprises replaceably positioning the container on the frame of a printing unit; gripping the printing form, that is formed as a printing plate, at a leading edge thereof by a clamping device of a form cylinder, that is formed as a plate cylinder; and rotating the cylinder so as to apply the printing plate to the plate cylinder by rotating the latter.
In accordance with another mode, the method of the invention includes returning the plate cylinder into the container, after a print job has been completed.
In accordance with a further mode, the method of the invention includes feeding a printing plate from the plate cylinder to a receiving container, after a print job has been completed.
In accordance with another aspect of the invention, there is provided a device for making-ready and feeding printing forms to a form cylinder of a printing machine, wherein at least one printing form is provided in a container in a rolled-up state and is unrollable so as to be fed to the form cylinder, comprising a receiving device for positioning the container on a frame of a printing unit so that a leading edge of a printing form formed as a printing plate is insertable into a clamping device of a form cylinder formed as a plate cylinder, the plate cylinder being rotatable for applying the printing plate to the plate cylinder.
In accordance with another feature, the device of the invention includes a rotatable guide element for guiding and pressing against the printing plate as it is being drawn onto the plate cylinder.
In accordance with a further feature of the invention, the rotatable guide element comprises two supporting rollers for pressing edge regions of the printing plates onto the plate cylinder.
In accordance with an added feature of the invention, the guide element is a roller for pressing the printing plate onto the plate cylinder.
In accordance with an additional feature of the invention, the device includes elastic rings disposed at spaced distances from one another on the roller.
In accordance with yet another feature of the invention, the guide element is automated for plate feeding and is engageable and disengageable automatically.
In accordance with yet a further feature of the invention, the container has a shaft received therein for retainingly guiding a trailing edge of a printing plate until the printing plate is removed from the container.
In accordance with yet an added feature of the invention, the container serves for accommodating a printing plate therein after a print job has been performed.
In accordance with yet an additional feature of the invention, for accommodating a printing plate in the container, a shaft received in the container for gripping a trailing edge of the printing plate after a print job has been performed, and for drawing the printing plate back into the container.
In accordance with still another feature of the invention, a drive is connected to the shaft.
In accordance with still a further feature of the invention, the drive includes a spring connected to the shaft, the spring being subjectible to tension when a printing plate is removed from the container, the printing plate being drawable back into the container by spring force after a print job has been completed.
In accordance with still an added feature of the invention, the device includes another container for accommodating a printing plate therein after a print job has been performed.
In accordance with still an additional feature of the invention, for accommodating a printing plate in the other container, a shaft is received in the other container for gripping a trailing edge of a printing plate after a print job has been performed, and drawing the printing plate into the other container.
In accordance with another feature of the invention, the device includes a drive connected to the shaft received in the other container.
In accordance with a concomitant feature of the invention, the drive includes a spring connected to the shaft received in the other container, the spring being subjectible to tension when a printing plate is removed from the first-mentioned container, the print
Evanisko Leslie J.
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Locher Ralph E.
Stemer Werner H.
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