Printing – Rolling contact machines – Rotary
Reexamination Certificate
2001-11-15
2004-04-20
Colilla, Daniel J. (Department: 2854)
Printing
Rolling contact machines
Rotary
C101S142000, C101S232000, C101S409000, C271S186000, C271S309000, C271S314000
Reexamination Certificate
active
06722277
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to a device for turning sheet-like material, a printing unit, a multicolor rotary printing press, and in particular to a storage device for turning a sheet-like material, such as is used, for example, on a turning device on rotary printing presses.
Published, Non-Prosecuted German Patent Application No. 41 40 762 A1 relates to a sheet guide device. This sheet guide device can be used selectively for recto and verso printing, and through the use of this sheet guide device the sheet can be turned, in recto and verso printing, according to the principle of the turning of the sheet trailing edge. Pneumatically operating devices and mechanical devices are provided under the impression cylinder preceding the turning drum. In order to provide a sheet guide device through the use of which sheets can be guided and led, free of smudges, in the turning phase, without a sheet bunch being formed, the impression cylinder is assigned a guide doctor blade which can be acted upon pneumatically at a given angle of inclination and which is provided with individual air outlet orifices. After the impression cylinder grippers have been opened, the printed sheet is released from the impression surface of the cylinder by blowing air, steered under the guide plate and, by the emerging blowing air, both held up and transported in the direction of the transfer cylinder, until the turning drum conveys the sheet further on.
German Patent No. 44 24 967 C2 relates to a method and a device for sheet turning. It proposes a method for sheet turning in sheet-fed rotary printing presses capable of being changed over from recto printing to recto and verso printing, according to the principle of trailing edge turning, in which, in recto and verso printing, a print carrier sheet guided on a cylinder is picked up by a pivotable sheet take-over system of a turning drum following the cylinder, at the tangent point of the turning drum and cylinder, by the trailing edge, and is transported further on. At the tangent point, the start of the print carrier sheet is released by the sheet grippers of the cylinder and, immediately after the tangent point, is guided on a path deviating from the surfaces of the cylinder under the turning drum.
The storage of sheet-like material on the impression cylinders of a rotary printing press requires free space underneath the impression cylinder, so that the sheet-like material can be received over its entire length. Thus, the sheet can be picked up and turned by the turning drum, without coming into contact with machine parts, casings of transfer drums, guide plates or other sheets. The space required for storage is contrary to the requirement for the sheet-like material to be printed out during transfer in the recto printing mode onto the transfer drum following the impression cylinder. The sheet-like material has already left the printing nip during transfer in recto printing. Consequently, in printing units with a single-drum turning device, a complete length of the maximum processable printing format must be provided as a freely available sheet transport zone in each case both between the transmission cylinder and the central gripper assembly to a following transfer drum and between the following transfer drum and the central transfer assembly to the preceding transfer drum, the space for the collision of the fittings provided there being taken into account. Furthermore, the necessary space requirement for accessibility and for fittings upstream of the printing nip must also be taken into account.
A further possibility for solving the technical problem described is to pivot the configuration of the cylinders to an extent such that the construction space for printing out and for storage is gained at the expense of the fittings upstream of the printing nip. This measure is detrimental to the quality of sheet guidance upstream of the printing nip, so that the print quality obtained is poorer. Moreover, there is a fear of serious effects on the accessibility of the fittings. This makes it more difficult to clean, to carry out adjustments and to perform servicing during maintenance work.
A further remedial possibility is to restrict the permissible print carriers for the recto and verso printing mode to those papers which remain adhering to the circumference of the impression cylinder and do not move away from the impression cylinder as a result of a gravitational influence and flexural rigidity. Through the use of this measure the collision space to be kept free could be restricted and the permissible format length increased. The restriction to only some permissible print carriers for rotary printing presses with turning devices is seriously detrimental to the processable print carriers and can only be a compromise solution.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a device for turning sheet material which overcomes the above-mentioned disadvantages of the heretofore-known devices of this general type and with which on the one hand, the format length of the sheet can be printed out completely and, on the other hand, the sheet-like material can be stored, completely free of collision, in the recto and verso printing mode, with the cylinder rolling conditions being maintained.
With the foregoing and other objects in view there is provided, in accordance with the invention, a device for turning sheet material, including:
an impression cylinder having an outer surface with a given curvature, the impression cylinder being configured to guide a sheet material received on the outer surface of the impression cylinder;
a first transfer cylinder preceding the impressing cylinder, the first transfer cylinder having an outer surface;
the impression cylinder and the first transfer cylinder defining a gusset region between the outer surface of the impression cylinder and the outer surface of the first transfer cylinder;
a second transfer cylinder following the impression cylinder; and
a throw-on device provided in the gusset region, the throw-on device contactlessly acting on the sheet material and causing the sheet material to assume, instead of a stretched position, a curved position corresponding to the given curvature of the outer surface of the impression cylinder such that a part of the sheet material is disposed in the gusset region.
In other words, according to the invention, a device for the turning of sheet-like material by use of a cylinder which guides sheet-like material and which is preceded by a transfer cylinder and followed by a transfer cylinder, the sheet-like material received on the outer surface of the impression cylinder being capable of being printed by a transmission cylinder, wherein, in the gusset of the outer surfaces between the impression cylinder and the preceding transfer drum, a contactlessly acting throw-on device is provided, which causes the sheet-like material to assume, instead of a stretched position, a curved position corresponding to the given curvature of the outer surface of the impression cylinder, with the gusset region being included.
Through the use of the throw-on device, configured and provided according to the invention, for the contactless holding of sheet-like, even relatively flexurally rigid sheet-like material, such as cardboard, the sheet-like material can be curved, free of smudges, onto the impression cylinder, so that no collisions of the ends of the sheet-like material, in particular when the latter assumes the stretched position, with fittings provided underneath the cylinders guiding sheet-like material and with the outer surface of the cylinders guiding the sheet-like material can occur. Through the use of the throw-on device proposed according to the invention, the tendency of relatively flexurally rigid sheet-like material, such as cardboard, to stretch out straight from a curved position can be counteracted. Through the use of the throw-on device proposed according to the invention, the involute peeling-off movement of the
Colilla Daniel J.
Culler Jill E
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Locher Ralph E.
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