Sheet feeding or delivering – Feeding – Separators
Reexamination Certificate
2001-04-03
2004-02-03
Bollinger, David H. (Department: 3653)
Sheet feeding or delivering
Feeding
Separators
C271S268000, C271S084000
Reexamination Certificate
active
06685182
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to a sheet-fed printing machine having at least one feed system for feeding sheets thereto from a feeder, the sheet-fed printing machine having at least one front lay serving to align the leading edge of the sheets to be processed, and a method of operating the sheet-fed printing machine.
The published German Patent Document DE 195 03 739 C1 reveals a sheet-fed printing machine of the type mentioned hereinbefore. It has, amongst other components, a feeder, a front lay, a pre-gripper including a gripper bar, and a feed cylinder. The front lay and the gripper bar are constructed so as to be pivotable and are coupled to the drive of the sheet-fed printing machine so as to be displaced at the cycle rate of the machine. The stacked sheets are separated in the feeder and subsequently aligned by the front lay so that the leading edge thereof extends exactly transversely with respect to the transport direction of the sheets. At the front lay, the sheet is gripped by the gripper bar and transported onwards to the feed cylinder. When preparing for a new print job, wherein a new printing image is to be printed onto the sheets, the feeding of the sheets in the feeder is stopped and at least one plate cylinder within the sheet-fed printing machine has an image set thereon directly with the aid of a laser, in an inkjet method, by thermal transfer or the like. During the setting of the image or imaging operation, the drives of the sheet-fed printing machine continue to run operatively, as well, the feed roller, amongst others, thus rotating at machine speed, and the front lay and the gripper bar being displaced oscillatingly at a corresponding speed. As a result of the movements of the front lay and the gripper bar, oscillations are introduced into the machine and tend to disrupt the setting of the image on the plate cylinder. It is often the case that, in order to set the image, the machine speed is increased to such an extent that it corresponds to a printing throughput of 16,000 sheets per hour or more, for example. As a result, the oscillations produced by the oscillating pre-gripper and front lay are further amplified.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a sheet-fed printing machine of the type mentioned at the introduction hereto, and a method that can be implemented therewith, wherein disruptions caused by oscillations during the setting of an image or imaging operation can be avoided, at least to a great extent.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a sheet-fed printing machine having a feed system for feeding sheets from a sheet feeder to the sheet-fed printing machine, and an imaging device for setting an image on a printing plate disposed on the plate cylinder, the feed system comprising at least one oscillatingly moving pregripper and a drive device for the feed system, the pregripper being uncoupled from the drive device.
In accordance with another feature of the invention, the sheet-fed printing machine includes a lever mechanism for driving the pregripper.
In accordance with a further feature of the invention, the pregripper has at least one gripper bar which is displaceable at the cyclic rate of the printing machine.
In accordance with an added feature of the invention, the displacement at the cyclic rate of the printing machine is non-uniform.
In accordance with an additional feature of the invention, the displacement at the cyclic rate of the printing machine is in an oscillatory manner.
In accordance with yet another feature of the invention, the pregripper is disposed between the sheet feeder and a feed cylinder.
In accordance with yet a further feature of the invention, the sheet-fed printing machine includes a blocking device for blocking the lever mechanism in a given functional position.
In accordance with yet an added feature of the invention, the drive device is constructed as a cam drive having at least one cam disk connected to a drive shaft so as to be fixed against rotation relative thereto, the cam disk cooperating with a first pivoting lever of the lever mechanism, and being pivotable about a fixed axis.
In accordance with yet an additional feature of the invention, the sheet-fed printing machine includes a pressing device for pressing the first pivoting lever against the cam disk.
In accordance with still another feature of the invention, the lever mechanism has a second pivoting lever connected to a shaft for the pregripper so as to be fixed against rotation relative thereto, and a gripper bar is fixed to the pregripper shaft.
In accordance with still a further feature of the invention, the pressing device is in cooperative engagement with at least one of the pregripper shaft and the second pivoting lever.
In accordance with still an added feature of the invention, the first and the second pivoting levers are articulatedly connected to a coupling element.
In accordance with still an additional feature of the invention, the first pivoting lever has at least one supporting roller which, in a non-blocked state of the lever mechanism, rolls on the cam disk, the supporting roller, in a blocked state of the lever mechanism, being located at a given distance from the rotating cam disk.
In accordance with another feature of the invention, the gripper bar has at least one gripper, and the feed system includes a feed cylinder formed, for the at least one gripper, with a respective circumferential groove into which the at least one gripper is dippable as it approaches the feed cylinder.
In accordance with a further feature of the invention, the gripper bar has a plurality of grippers, and the feed system includes a feed cylinder formed, for the plurality of grippers, with a plurality of respective circumferential grooves into which the grippers, respectively, are dippable as they approach the feed cylinder.
In accordance with an added feature of the invention, a respective circumferential groove is of such depth that even when the at least one gripper is at a minimal distance from the axis of rotation of the feed cylinder, there is an interspace between the at least one gripper and the bottom of the respective circumferential groove.
In accordance with another aspect of the invention, there is provided a sheet-fed printing machine having a feed system for feeding sheets from a sheet feeder to the sheet-fed printing machine, and an imaging device for setting an image on a printing plate disposed on a plate cylinder, the feed system comprising at least one reciprocatingly pivotable front lay and a drive device for the front lay, the front lay being uncouplable from the drive device.
In accordance with a further feature of the invention, the sheet-fed printing machine includes a displacement device having a lever mechanism which is displaceable by the drive device.
In accordance with an added feature of he invention, the displacement of the lever mechanism is non-uniform.
In accordance with an additional feature of the invention, the displacement of the lever mechanism is in an oscillating manner.
In accordance with yet another feature of the invention, the drive device is constructed as a cam drive having at least one cam disk connected to a drive shaft so as to be fixed against rotation relative thereto, the cam disk cooperating with a roller lever, and being pivotable about a fixed first pivot shaft.
In accordance with yet a further feature of the invention, the lever mechanism has a coupling rod articulatedly connected to a roller lever and a lever arm having the front lay and being pivotable about a fixed second pivot shaft.
In accordance with yet an added feature of the invention, as viewed in vertical direction, in a raised position of the coupling rod, the front lay is displaceable into an aligning position and, in a lowered position of the coupling rod, is displaceable into a standby position.
In accordance with yet an additional feature of the invention, the sheet-fed print
Berti Christopher
Herrmann Bernd
Lötsch Kurt
Schmidt Arnd
Weisbrodt Ulrike
Bollinger David H.
Heidelberger Druckmaschinen AG
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