Printing – Rolling contact machines – Rotary
Reexamination Certificate
2001-11-21
2004-01-27
Colilla, Daniel J. (Department: 2854)
Printing
Rolling contact machines
Rotary
C101S232000, C101S409000, C101S483000, C271S186000, C271S277000, C271S309000, C271S314000
Reexamination Certificate
active
06681696
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a turning or reversing device for a real or flat sheet-like material, which is printable on both sides thereof, with a storage device for the sheet-like material to be turned, which is assigned to the turning device.
The published German Patent Document DE 41 40 762 A1 is concerned with a sheet guiding device which may be used selectively in recto and verso printing mode, a respective sheet being turnable by this device, during recto and verso printing, in accordance with the principle of sheet trailing-edge turning, and pneumatically operating and mechanical devices are provided under the impression cylinder preceding the turning drum. In order to provide a sheet guiding device by which the sheet can be guided and led in a smudge-free manner in the turning or reversing phase, without formation of a sheet wad, the impression cylinder has assigned thereto, at an angle of inclination &bgr;, a guide doctor blade capable of being acted upon pneumatically and provided with individual air outlet orifices. After impression cylinder grippers have opened, the printed sheet is released from the printing surface of the cylinder by blowing or blast air, steered under the guide plate and both held up and transported in the direction of the transfer cylinder by the emerging blowing air, until the turning drum conveys the sheet farther on.
The published German Patent Document DE 44 24 967 C2 is concerned with a method and a device for sheet turning or reversing. What is proposed is a method for sheet turning based upon the principle of trailing edge turning in sheet-fed rotary printing machines capable of being converted from recto printing to recto and verso printing mode, in which method, in recto and verso printing, a print carrier sheet guided on a cylinder is gripped at the trailing edge thereof by a pivotable sheet take-over system of a turning drum following or located downline from the cylinder, at the tangent point of the turning drum and the cylinder, and is transported further. At the tangent point, the start of the sheet carrier sheet is released by the sheet gripper of the cylinder and, immediately after or downline from the tangent point, is guided on a path deviating from the surfaces of the cylinder under the turning drum.
Storage of sheet-like material on the impression cylinders of a rotary printing machine requires free space below the impression cylinder, so that the sheet-like material can be received over the entire length thereof. Thus, the sheet can be gripped and turned by the turning drum without coming into contact with machine parts, casings of transfer drums, guide plates or other sheets. The requirement for storage space is contradictory or opposed to the requirement that the sheet-like material should be printed out during the transfer in recto printing mode to the transfer drum following the impression cylinder. If the sheet-like material is intended to have already left the printing nip during transfer in recto printing, it is necessary, in printing units with a single-drum turning device, to provide in each case a complete length of the maximum processable printing format as a freely available sheet transport stage both between the transmission cylinder and the gripper median line to a following or downline transfer drum and between the following or downline transfer drum and the transfer median line to the preceding or upline transfer drum, taking into account the collision space of the fittings provided thereat. Furthermore, it is also necessary to take into account the necessary space requirement for accessibility and for the fittings in front of or upline from the printing nip.
A further possibility for solving the depicted technical problem is to pivot the arrangement of cylinders to an extent that the construction space for printing out and storage is gained at the expense of the fittings in front of or upline from the printing nip. This measure, however, is detrimental to the quality of sheet guidance in front of or upline from the printing nip, so that the print quality which is attained decreases. Moreover, serious effects on the accessibility of the fittings are to be feared. This makes it difficult to clean, perform settings and conduct servicing during maintenance work.
A further possibility for a remedy is to restrict the permissible print carriers for the recto and verso printing mode to those print carriers which remain adhering to the circumference of the impression cylinder and which do not move away from the impression cylinder due to the influence of gravity and to flexural rigidity. By this measure, the collision space to be kept free could be restricted and the permissible format length could be enlarged. However, the restriction to only some permissible print carriers for rotary printing machines with turning devices is seriously detrimental to the processable print carriers and can only be a compromise solution.
SUMMARY OF THE INVENTION
In view of the developments in the prior art, which have been outlined, and the technical problem, which has been described, it is an object of the invention to provide a turning or reversing device with a storage device for flat sheet-like material wherein the storable sheet length is maximized during the turning or reversing of the sheet-like material.
With the foregoing and other objects in view, there is provided, in accordance with a first aspect of the invention, in combination, a device for turning sheet-like material, with an impression cylinder for guiding the sheet-like material, the impression cylinder being preceded by a first transfer cylinder and followed by a second transfer cylinder, the sheet-like material being receivable on an outer jacket surface of the impression cylinder so as to be printable by a third transfer cylinder, comprising a storage device, and a device for imparting a deformation in the sheet-like material during entry thereof into the storage device and while the sheet-like material is gripped at an edge thereof.
In accordance with another feature of the invention, the storage device extends below the impression cylinder and the first and the second transfer cylinders.
In accordance with a further feature of the invention, the storage device has a contour for guiding a print carrier, the contour corresponding to a wedge-shaped region between two of the cylinders which are mutually cooperating.
In accordance with an added feature of the invention, the storage device has, below the impression cylinder, a nip width narrowing continuously in a direction of entry of the sheet-like material.
In accordance with an additional feature of the invention, the storage device has a run-on slope in a wedge-shaped region of the nip.
In accordance with yet another feature of the invention, the combination includes a retaining element arranged at the storage device in an upper region thereof, below a transfer median line, for retaining in the storage device the sheet-like material which has entered the storage device.
In accordance with yet a further feature of the invention, the retaining element has perforations formed therein like comb tines for allowing passage therethrough of holding elements of the impression cylinder for gripping the sheet-like material.
In accordance with yet an added feature of the invention, at least one coating is provided on the retaining element for damping impacts of the sheet-like material.
In accordance with yet an additional feature of the invention, the combination includes an encapsulated damping gel provided on the retaining element.
In accordance with still another feature of the invention, the combination includes cyclically activatable blowing nozzles provided on the impression cylinder for ejecting the sheet-like material into the retaining element.
In accordance with still a further feature of the invention, the combination includes cyclically activatable ejector pins provided on the impression cylinder for ejecting the sheet-like material into said retaining element.
In
Colilla Daniel J.
Culler Jill E.
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Maybeck Gregory L.
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