Sheet feeding or delivering – Feeding – With means to align sheet
Reexamination Certificate
2001-11-09
2003-08-12
Walsh, Donald P. (Department: 3653)
Sheet feeding or delivering
Feeding
With means to align sheet
C271S268000, C271S277000
Reexamination Certificate
active
06604739
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method and a device for aligning flat copies in sheet-processing machines, such as multicolor rotary printing machines having a plurality of printing units arranged behind one another or in tandem.
The published German Patent Document DE 29 24 636 A1 is concerned with a control device for a sheet gripper device, wherein the sheet grippers are movable in axial direction. A number of sheet grippers for gripping the leading edge of a printed sheet between gripper fingers and gripper pads is provided, the gripper pads being fixed onto a gripper pad rail supporting the gripper spindle in bearings. The sheet grippers are arranged so as to be displaceable in the axial direction of the gripper spindle and of the gripper pad rail, for the purpose of aligning a printed sheet laterally, the gripper pad rail being fixed to the body of an impression cylinder and a transfer drum, respectively, or to the body of a pregripper by leaf-type spring supports which are deflectable in the axial direction of the gripper spindle and the gripper pad rail. The axial displacement of the gripper pad rail is performed by an actuating motor, which can be driven via a servo-controller circuit by light-sensitive elements which sense at least one edge of a printed sheet in relation to a locally fixed reference line.
With such a construction, lateral displacement of a sheet material in relation to the conveying direction thereof is possible, but the lateral alignment according to this construction must necessarily be subject to inaccuracies as a result of the play which is necessarily inherent therein due to the mechanical components.
Published German Patent Document DE 36 44 431 A1 discloses a sheet gripper device in a rotary printing machine having sheet grippers which are likewise movable in the axial direction. The sheet gripper device is suitable for cylinders and drums of sheet-fed rotary printing machines, sheet grippers being accommodated on an axially displaceable carriage for the purpose of lateral alignment of the sheets to be printed. The axial movement of the axially displaceable carriage that accommodates the sheet grippers is produced by a control cam, which is arranged so that it is pivotable in the direction of a side surface of the drum and away therefrom.
For register accuracy and for freedom from ghosting, which is to be preserved, a reproducible position of the sheet material conveyed through a printing machine is imperative. In the case of a sheet-fed rotary printing machine, the sheet material is generally aligned in the feeder and taken over by gripper systems, which can include a pregripper system for accelerating the sheet to machine speed. The gripper systems convey the sheet material, with an interposition of various transfer points, as far as the sheet delivery. The alignment process which takes place in the feeder of the sheet material is relatively complicated, because many mechanical components are involved in the alignment process, and the driveability thereof at high speeds of 13,000 prints per hour or more approaches the limits thereof. Heretofore, printing criteria, such as the maintenance of the circumferential and the lateral register, could be corrected only on average by the register.
SUMMARY OF THE INVENTION
Considering the developments in the prior art and the indicated technical problem, it is an object of the invention of the instant application to provide a method and a device for aligning a cylinder in a sheet-processing machine.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a method of aligning flat copies in a sheet-processing machine, which comprises the steps of determining the actual position of a sheetlike material in relation to a coordinate system; implementing a nominal position of a cylinder that accommodates the sheetlike material to be aligned on the jacket surface of the cylinder by correctively controlling non-contacting radial/axial magnetic bearings so as to compensate for position changes of one of the cylinder and components thereof from the nominal position; and maintaining the cylinder in the nominal position thereof until the aligned sheet material is transferred to transport units arranged farther downline.
In accordance with another mode, the method of the invention includes guiding the sheetlike material during the rotation of the cylinder, and detecting the actual position of the leading edge and side edges of the sheetlike material by sensors.
In accordance with a further mode, the method includes independently displacing the cylinder, which guides the sheetlike material, on the drive side and on the operating side of the cylinder, for correcting a skewed position of the sheetlike material.
In accordance with an added mode, the method includes performing a like displacement of the cylinder, which guides the sheetlike material, both on the drive side and on the operating side of the cylinder, for correcting a circumferential position of the sheetlike material.
In accordance with an additional mode, the method includes axially displacing the cylinder, which guides the sheetlike material, for correcting the erroneous position of the sheetlike material.
In accordance with yet another mode, the method includes monitoring the nominal position of the cylinder, which guides the aligned sheetlike material, by axial and radial sensors, respectively, for controlling the radial/axial magnetic bearings.
In accordance with another aspect of the invention, there is provided a method of aligning cylinders carrying a printed image in a printing machine, which comprises the steps of determining the actual position of the printed image in relation to a coordinate system; and implementing a nominal position of a cylinder that accommodates the printed image to be aligned on the jacket surface of the cylinder by correctively controlling radial/axial magnetic bearings so as to compensate for position changes of one of the cylinder and components thereof from the nominal position.
In accordance with a further mode, the method of the invention includes, during the rotation of the cylinder carrying the printed image, detecting by sensors the actual position of the cylinder carrying the printed image.
In accordance with an added mode, the method includes independently displacing the cylinder, which carries the printed image, on the drive side and on the operating side of the cylinder, for correcting a skewed position of the printed image.
In accordance with an additional mode, the method includes axially displacing the cylinder, which carries the printed image, for correcting the erroneous position of the printed image.
In accordance with a further aspect of the invention, there is provided a device for aligning flat copies in sheet-processing machines such as multicolor rotary printing machines or digitally operating printing machines wherein sheetlike material is conveyed by gripping devices on a circumferential surface of a driven cylinder, comprising radial/axial bearings for mounting the driven cylinder without contact therewith, the driven cylinder being accommodated in side walls and serving to carry the sheetlike material, and sensors assigned to the radial/axial bearings for detecting axial and radial position changes, respectively.
In accordance with an added aspect of the invention, there is provided a device for aligning printed images in printing machines, such as multicolor rotary printing machines or digitally operating printing machines wherein a printed image is carried by at least one cylinder selected from the group thereof consisting of printing form cylinders and transfer cylinders, comprising radial/axial bearings for mounting the cylinder without contact therewith, the cylinder being accommodated in side walls, and sensors assigned to the radial/axial bearings for detecting axial and radial position changes, respectively.
In accordance with another feature of the invention, accommodated on the cylind
Förch Peter
Henn Andreas
Bower Kenneth W
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Locher Ralph E.
Stemer Werner H.
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