Printing – Rolling contact machines – Rotary
Reexamination Certificate
1999-10-14
2001-10-16
Yan, Ren (Department: 2854)
Printing
Rolling contact machines
Rotary
C101S216000
Reexamination Certificate
active
06302021
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to a sheet-fed printing machine having an impression cylinder and a movable cylinder that can be thrown onto the impression cylinder and can be moved into a spaced position far removed from the impression cylinder.
A sheet-fed printing machine of this type is described in the published European Patent Document EP 0 477 283 B1. This sheet-fed printing machine has a withdrawable coating device with a coating cylinder which, in relation to an impression cylinder, can be moved into an operating position in order to coat the printing-material sheet resting on the impression cylinder, into a disengaged position at a slight distance from the impression cylinder, and into a position far removed from the impression cylinder and designated a second position.
A disadvantage of this sheet-fed printing machine is that when printing stiff printing-material sheets, for example, sheets made of heavy cardboard, without an in-line coating with the coating device, smearing of the yet-fresh printing ink is not ruled out. If in this case the coating cylinder were to remain in the disengaged position, the printing ink would be smeared onto the coating cylinder, and the printed image would be smeared due to this contact. If the inactive coating cylinder were to remain in the so-called second position, it would then be no longer possible to carry the trailing end of the sheet close to the impression cylinder, because of the inherent stiffness of the printing-material sheet, inasmuch as the coating cylinder located in the second position is no longer able to hold the printing-material sheet on the impression cylinder. The unstable position of the transported printing-material sheet would result in smearing of the printing ink onto other machine parts and possibly even to damage to the printing-material sheet.
The published German Patent Document DE 297 10 252 U1 contains a description of a guide device that is assigned to transfer drums and is provided with guide plates which can be pivoted and moved by pushing or sliding. Although this guide device can be used to carry stiff materials on the sheet transfer drums, and the transfer drums are easily accessible for maintenance and cleaning, the guide device is not suitable for use in conjunction with an impression cylinder and a cylinder that can be thrown onto the latter.
Furthermore, a sheet-fed printing machine that is not of the foregoing general type is described in the published German Patent Document DE 43 18 777 C2. This sheet-fed printing machine has a printing unit with a blanket cylinder and an impression cylinder. When the printing unit is not involved in printing, there is a spacing between the blanket cylinder and the impression cylinder that is about 2 mm distance and is therefore very small. The blanket cylinder of this inactive printing unit, that is located close to the impression cylinder of the unit, cannot be maintained or cleaned during printing with other printing units. One reason for this disadvantage is the poor accessibility of the blanket cylinder in the described operating situation of the printing machine. In addition, the use of two blast tubes or blower pipes arranged in the wedge-shaped space upline and downline of the printing zone is disadvantageous. Although the blast tubes permit a quiet sheet run in the case of thin sheets of paper, this cannot be achieved in the case of thick sheets of cardboard or pasteboard.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an easily maintained sheet-fed printing machine wherein, in particular, stiff printing-material sheets can be conveyed without smearing and in a stable position through an inactive printing-machine unit of the printing machine.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a sheet-fed printing machine having an impression cylinder and a movable cylinder that can be thrown onto the impression cylinder and movable into a spaced position far removed from the impression cylinder, comprising a sheet guide element assigned to the impression cylinder, the sheet guide element being movably mounted for guiding a printing-material sheet carried on the impression cylinder.
In accordance with another feature of the invention, the movable cylinder and the sheet guide element are selectively throwable onto the impression cylinder at substantially the same circumferential location on the impression cylinder.
In accordance with a further feature of the invention, the sheet guide element is pivotably mounted.
In accordance with an added feature of the invention, the sheet guide element is a sheet guide plate.
In accordance with an additional feature of the invention, the sheet guide element is selectively movable into a first position and into a second position, the sheet guide element, in the first position, extending through between the movable cylinder and a blower and, in the second position, being thrown onto the impression cylinder at a spaced distance therefrom.
In accordance with yet another feature of the invention, a minimum circumferential distance between the movable cylinder disposed in the spaced position and the impression cylinder is a plurality of decimeters.
In accordance with a concomitant feature of the invention, the printing machine includes a sheet transport drum for transferring a printing-material sheet to the impression cylinder, the printing-material sheet being carried by the sheet transport drum and being held at a leading edge thereof by grippers of the sheet transport drum, so that the printed-material sheet hangs down freely.
The sheet-fed printing machine having an impression cylinder and a movable cylinder that can be thrown onto the impression cylinder and can be moved into a spaced position far removed from the impression cylinder is distinguished by the fact that the impression cylinder has a sheet guide element assigned thereto, the sheet guide element being movably mounted for guiding a printing-material sheet carried on the impression cylinder.
The advantages of the invention manifest themselves in the operation of a printing machine which comprises a printing-machine unit and a further printing-machine unit arranged downstream of the latter, as viewed in the sheet transport direction, when, in a specific operating mode, for example, the operating mode of printing without in-line finishing, the printing-machine unit is active and the further printing-machine unit is inactive. The impression cylinder can be a constituent part of the further printing-machine unit, and the sheet guide element can be thrown onto the impression cylinder, so that the sheet guide element guides the printing-material sheet transported by the impression cylinder while the movable cylinder is located in the spaced position far removed from the impression cylinder. This permits the positionally stable and smear-free transport of the printing-material sheet freshly printed or coated in the printing-machine unit through the inactive further printing-machine unit and past the movable cylinder, while the movable cylinder can in the meantime be cleaned and maintained, for example.
The further printing-machine unit can be a so-called finishing unit of the sheet-fed printing machine, the unit being arranged downline of at least one printing unit and preferably a number of printing units. The term finishing unit is understood to mean, for example, a coating, impression, numbering, processing or cleaning unit. The further printing-machine unit may, however, also be a printing unit of a number of identical printing units, arranged in a row one after the other, of the sheet-fed printing machine.
The sheet-fed printing machine can be constructed as a sheet-fed rotary offset printing machine. In this case, the printing-machine unit can be one of a number of offset printing units and the further printing-machine unit can be a coating unit.
Other features which are considered as characteristic for the invention are set forth
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Lerner Herbert L.
Stemer Werner H.
Yan Ren
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