Printing – Cleaning attachments
Reexamination Certificate
2002-03-27
2004-10-19
Hirshfeld, Andrew H. (Department: 2854)
Printing
Cleaning attachments
C101S232000, C101S420000
Reexamination Certificate
active
06805050
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a printing unit for a machine for processing flat printing materials, in particular a sheet-processing rotary printing machine, having a feeding cylinder for loading the printing unit with the printing materials in a processing direction, and a device for removing particles adhering to the surface of the printing materials, the particle-removing device comprising a blast or blowing device for separating the particles from the printing materials without contact, and a suction device for discharging the separated particles. The invention also relates to a machine for processing flat printing materials and to a machine equipped with at least one such printing unit, and also a feeder drum for such a printing unit.
For satisfactorily printing flat printing materials, such as sheets, for example, particles adhering to the surface of the sheets must be removed. The particles are, in particular, dust, and possibly separating agents which prevent adjacent sheets in a pile or stack from adhering to one another, in a case wherein printing is performed in a second pass through a printing machine.
In order to dispose of such particles, suction brushes connected upstream of a printing nip have become known heretofore, which loosen the particles mechanically from the surface of the printing materials and removes them by vacuum or negative pressure. As a rule, the suction brushes are be arranged between the impression cylinder and a feeding drum or cylinder that transfers the printing material to the impression cylinder, in order to feed the printing material dust-free to the printing nip. In order to obtain a printed a image that is free of transverse stripes, the image should have been completely printed out at the time of transfer to a transfer device, such as a transfer cylinder, for example.
Disadvantageously, when using suction brushes, there is, on the one hand, a possibility of mechanical damage occurring to the printing materials, it being possible, moreover, for paper particles loosened as a result of abrasion to lead to the formation of hickeys or lint, so that the suction brush requires continual installation and removal in order to clean it and remove the hickeys. This applies in particular to sensitive printing materials and to repeated passes or throughput, respectively, during multicolor printing. On the other hand, the suction brush requires additional space in the overall construction space of the printing unit, which is limited in any case, so that the feeding drum has to be arranged at a relatively great distance from the printing nip, which results in the printing material, for example, transferred from a pregripper to the feeding drum and then to the impression cylinder, being deflected over large circumferential sections of the feeding drum and of the impression cylinder. In the case of relatively stiff printing materials, in particular, this leads to scratching and/or marking thereof. Furthermore, because of the space required for the suction brush arranged between the feeding drum and the printing nip, for a given inclination and output height of a feeding table providing the printing materials to the pregripper, guidance of the printing material on the feeding table so as to be tangential to the feeding drum is not possible, so that, in particular in the case of thin printing materials, as the latter are transferred to the feeding drum, there is a risk of forming an inlet corrugation, by the fact that the printing material, which is gripped at the leading edge thereof by the pregripper, is bent upwardly in a direction towards the feeding drum at the point of contact with the feeding drum. Otherwise, it would be necessary for a feeding table of given output height, from which the printing material is transferred to the feeding drum by the pregripper, to be built quite long due to the feeding drum being arranged relatively far below the impression cylinder, which would be complicated from a construction standpoint and costly.
The published German Patent Document DE 199 03 887 A1 describes a printing machine having a first printing unit for printing the front side of sheets and a second printing unit for printing the rear side. Both printing units are equipped with devices for cleaning the sheets to be printed, the cleaning devices being buildable, on the one hand, by suction brushes, and on the other hand, by non-contacting or contact-free devices, such as blowing-air or blast, suction or electrostatic devices. The disadvantages mentioned hereinabove result from the requirement for additional space demanded by the respective cleaning device.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a printing unit with a device for removing particles, as described in the introduction hereto, in a simple and cost-effective manner and wherein the space required for the device for removing particles, which adhere to the surface of the printing material, is minimized. It is, furthermore, an object of the invention to provide an accordingly improved machine for processing flat printing materials equipped with such a printing unit, and to provide an improved feeding cylinder for such a printing unit.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a printing unit for a machine for processing flat printing materials, comprising a feeding cylinder for loading the printing unit with the printing materials in a processing direction, and a device for removing particles adhering to the surface of the printing materials, the particle-removing device further comprising a blowing device for separating the particles from the printing materials without contact, and a suction device for discharging the separated particles, both the blowing device and the suction device being formed by blowing and suction chambers arranged within the feeding An cylinder and having a fluidic connection to surroundings of a By jacket surface of the feeding cylinder.
In accordance with another feature of the invention, both the blowing chamber and the suction chamber extend at least approximately over the entire width of the feeding cylinder.
In accordance with a further feature of the invention, both the blowing chamber and the suction chamber are arranged fixed against rotation.
In accordance with an added feature of the invention, the printing unit further comprises lines received in the feeding cylinder at least approximately centrally with respect to the feeding cylinder, via which both the blowing chamber and the suction chamber are actable upon by positive and negative pressure, respectively.
In accordance with an additional feature of the invention, the blowing chamber is arranged upstream of the suction chamber with respect to the processing direction.
In accordance with yet another feature of the invention, the suction chamber directly adjoins the blowing chamber.
In accordance with yet a further feature of the invention, the suction chamber is connected to a larger section of the jacket surface of the feeding cylinder than is the blowing chamber.
In accordance with yet an added feature of the invention, the jacket surface of the feeding cylinder connected to the suction chamber extends over a sector angle between 30° and 150°.
In accordance with yet an additional feature of the invention, the sector angle is between 60° and 120°.
In accordance with still another feature of the invention, the jacket surface of the feeding cylinder connected to the blowing chamber extends over a sector angle between 1° and 20°.
In accordance with still a further feature of the invention, the sector angle is between 1° and 10°.
In accordance with still an added feature of the invention, the feeding cylinder forms a hollow cylinder having a multiplicity of boreholes extending through the jacket surface thereof.
In accordance with still an additional feature of the invention, the printing unit further comprises thin webs formed in the jacket surface of the
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Hinze Leo T.
Hirshfeld Andrew H.
Mayback Gregory L.
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