Method and apparatus for reversing sheet material in sheet-processing machines

Information

  • Patent Grant
  • 6739252
  • Patent Number
    6,739,252
  • Date Filed
    Tuesday, July 30, 2002
    21 years ago
  • Date Issued
    Tuesday, May 25, 2004
    20 years ago
Abstract
A method and an apparatus for reversing sheet material in a sheet-processing machine having at least two printing units, a reversing drum with a gripper system, and an impression cylinder that can be operated as a storage drum in perfecting mode and to which a further gripper system for one edge of the sheet material is assigned. In perfecting mode, one of the edges of the sheet material is gripped at an angular offset before the transfer centerline between the reversing drum and the storage drum, before the edge of the sheet material fixed to the storage drum is released.
Description




BACKGROUND OF THE INVENTION




Field of the Invention




The invention relates to a method and apparatus for reversing sheet material in sheet-processing machines, such as sheet-fed printing presses, having a plurality of printing units disposed one behind another.




German Patent DE 26 33 183 C, corresponding to U.S. Pat. No. 4,165,689 to Giuiuzza, relates to an apparatus for reversing sheets in a multicolor rotary offset printing press. Such a press includes at least two printing units each having a plate cylinder, a transfer cylinder, and an impression cylinder, which are coupled together in terms of drive through circulating transmission elements. A reversing device associated with the transfer elements is provided, which includes a reversing cylinder having a gripper.




The gripper is driven and disposed such that the sheets that have already been printed on one side are gripped after they have passed a transfer cylinder and the sheets have been removed completely from a transfer device resting on the cylinder. The sheets printed on one side are gripped by a reversal mechanism, which acts at the trailing edge of the sheets, which, until this point, have still been held at the leading edge by the gripper of the reversing cylinder. As a result, these sheets are fed to the gripper of the transfer device again with the direction of advance reversed by a separate apparatus that can be configured as a swing gripper or as a table to which vacuum is applied.




German Published, Non-Prosecuted Patent Application DE 39 03 093 A1 discloses a sheet-reversing apparatus. According to such a solution of a sheet-reversing apparatus for in-line rotary printing presses, the impression cylinders of successive printing units are connected by at least one transfer drum. A storage drum is disposed downstream of a transfer drum, parallel to the recto printing sheet guidance. The sheet-reversing apparatus can be uncoupled from the rectoprint sheet guide cylinders during recto printing operation. Provided on a sheet-reversing apparatus is a format adjustment, which can be adjusted independently of the cylinders carrying sheets in recto printing.




German Published, Non-Prosecuted Patent Application DE 198 33 903 A1, corresponding to U.S. Pat. No. 6,401,610 to Becker et al., relates to a method for the transfer of a sheet trailing edge from an upstream cylinder of a sheet-fed rotary printing press. According to such a method for the transfer of the sheet trailing edge from a cylinder and its transfer to a gripper system of a reversing drum, a suction gripper is guided initially along the periphery of the cylinder until the suction gripper has securely gripped the sheet trailing edge. The trailing edge is then guided tangentially to the cylinder cover of the upstream cylinder into the periphery of the reversing drum, the sheet being tautened and end-compressed along a tangent to the cylinder. The sheet is then transferred under no tension to the gripper system of the reversing drum. A gear device used for such a purpose includes three drive systems that are coupled to one another and are controlled through stationary cams.




In single-drum reversing systems, in which the impression cylinder located upstream of the reversing drum acts as a storage drum in a perfecting mode (also referred to as a recto/verso mode or reversing mode), the storage length is not sufficient for a large-format sheet. Attempts have been made to peel the sheet material off the impression cylinder, according to a solution disclosed by German Published, Non-Prosecuted Patent Application DE 44 24 968, but problems have occurred with regard to in-register transfer of the sheet trailing edge. By placing pressure elements, attempts have been made to press onto the sheet, but this, in turn, entails problems with regard to smearing in the case of those sheets that do not have any print-free areas.




SUMMARY OF THE INVENTION




It is accordingly an object of the invention to provide a method and apparatus for reversing sheet material in sheet-processing machines that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that turns large-format sheet material in register when the overall space is limited.




With the foregoing and other objects in view, there is provided, in accordance with the invention, a method for reversing sheet material having edges in a sheet-processing machine having at least two printing units, including the steps of providing a gripper system on a reversing drum associated with at least one of the printing units, providing an impression cylinder operable as a storage drum in a recto/verso mode, the storage drum having a recto printing side and an impression-cylinder-side gripper system, the storage drum and the reversing drum defining a transfer centerline therebetween, and gripping, in the recto/verso mode, one of the edges of the sheet material at an angle before the transfer centerline with a holding and lifting system disposed parallel to the recto printing side of the storage drum before an edge of the sheet material fixed to the storage drum is released by the impression-cylinder-side gripper system.




With the objects of the invention in view, there is also provided a method for reversing sheet material having edges in a sheet-processing machine having at least two printing units, including the steps of providing a gripper system on a reversing drum associated with at least one of the printing units, providing an impression cylinder operable as a storage drum in a recto/verso mode, the storage drum having a recto printing side and an impression-cylinder-side gripper system, the storage drum and the reversing drum defining a transfer centerline therebetween, gripping a given edge of the sheet material with the impression-cylinder-side gripper system, and gripping, in the recto/verso mode, a given edge of the sheet material at an angle before the transfer centerline with a holding and lifting system disposed parallel to the recto printing side of the storage drum before the given edge is released by the impression-cylinder-side gripper system.




The advantages of the solution according to the invention can primarily be seen in the fact that, as a result of the early gripping of the sheet material at one edge before it passes the transfer centerline, early opening of the holding systems of the storage drum that grip the sheet material can be brought about. Such a configuration ensures that sheet material needing a large storage length can assume a substantially extended position underneath the storage drum. This prevents the sheet material from being able to run into the pocket area between storage drum and the transfer cylinder upstream of the latter and being damaged.




The holding and lifting system disposed outside the reversing drum tensions the sheet before it is turned and transfers the sheet to the gripper system of the reversing drum. The configuration ensures that the sheet material is transferred in register to the reversing drum so that both sides of the sheet material can be printed with the same quality. The in-register gripping of the sheet trailing edge of the sheet material is ensured by the fact that, at the time that it is gripped, a frictional or positive connection between the holding and lifting system and the outer surface of the impression cylinder serving as a storage drum is produced.




In a development of the idea on which the invention is based, the trailing edge of the sheet material is attracted by suction to the circumference of the storage drum before reaching the transfer centerline and is tensioned in the circumferential direction. Gripping the sheet trailing edge of the sheet material in the tensioned state of the sheet material ensures its in-register gripping and transfer to the reversing drum downstream of the storage drum. In accordance with the method proposed by the invention, the edge of the sheet material fixed to the circumference of the storage drum is released before it reaches a pocket between the storage drum and a transfer drum upstream of the latter. The early release of the edge of the sheet material fixed to the storage drum permits the deflection of large-format sheet material, needing a great storage length, into the free space underneath the storage drum so that, during the reversing action, the material does not experience any contact with rotating and stationary printing-unit components.




The assumption of a substantially extended position of the sheet material is assisted by rotation of the gripper system of the reversing drum that, during the rotation of the reversing drum, holds the gripped edge of the sheet material substantially in the horizontal position.




In accordance with another mode of the invention, a trailing edge of the sheet material is held in a gripper closure before reaching the transfer centerline.




In accordance with a further mode of the invention, one of a form-fitting connection and a frictional connection is produced between the gripper closure and the impression cylinder.




In accordance with an added mode of the invention, a transfer drum is placed upstream of the storage drum with respect to a sheet material transport direction and an edge of the sheet material fixed on a circumference of the storage drum is released before reaching a pocket between the storage drum and the transfer drum. Preferably, the pocket is disposed between the storage drum and the transfer drum at a downstream side of the storage drum with respect to a sheet material transport direction.




In accordance with an additional mode of the invention, the gripper system of the reversing drum is rotated to transfer the trailing edge of the sheet material into a substantially extended position. Preferably, the sheet material assumes the substantially extended position underneath the storage drum.




With the objects of the invention in view, there is also provided an apparatus for reversing sheet material having edges in a sheet-processing machine, including at least two printing units, at least one of the printing units having a reversing drum having a gripper system, an impression cylinder operable as a storage drum when recto/verso printing, the storage drum having a recto printing side, a circumference, and an impression-cylinder-side gripper system, the storage drum and the reversing drum defining a transfer centerline therebetween, a holding and lifting system disposed parallel to the recto printing side of the storage drum, the holding and lifting system adapted to lift an edge of the sheet material off the circumference of the storage drum before the transfer centerline and to transfer the lifted edge into the gripper system of the reversing drum one of directly and along a path.




In accordance with yet another feature of the invention, the holding and lifting system lifts one edge of the sheet material from the circumference of the storage drum before the transfer centerline and transfers the edge, directly or along a path, into the gripper system of the reversing drum.




In accordance with yet a further feature of the invention, the system is constructed as a self-supporting bridge that circulates relative to the storage drum, of which one or more can be associated with the circumference of the impression cylinder functioning as a storage drum. The holding and lifting system according to the first variant of the solution according to the invention includes a driven swinging element that can be set cyclically against the outer surface of the storage drum and that, at a distance φ before the transfer centerline between storage drum and reversing drum, has a holding element for gripping the sheet trailing edge of the sheet material accommodated on the storage drum. The holding element, in turn, includes a suction element that can be moved at right angles to the outer surface of the storage drum and with which the trailing edge of the sheet material in the circumferential direction on the storage drum can be tensioned in the radial direction and lifted off the outer surface of the storage drum. To assist the action of lifting the sheet trailing edge of the sheet material, at the moment it is gripped between the holding and lifting system and the impression cylinder functioning as a storage drum, a form-fitting or frictional connection is produced, it being possible to provide on the holding element a fixing element that can be displaced in the horizontal direction and is configured such that it can be moved into and out of the holding element. By such a displaceable fixing element in the holding and lifting system, it is possible to move under the sheet trailing edge of the sheet material lifted off the outer surface of the storage drum so that it is ensured that the sheet trailing edge of the sheet material, to be gripped in register, is gripped by the gripper system associated with the reversing drum in a tension and aligned state.




In accordance with yet an added feature of the invention, the holding element has a holding finger adapted to move under the trailing edge of the sheet and to lift off the trailing edge from the outer surface of the storage drum.




In accordance with yet an additional feature of the invention, the holding and lifting system is constructed substantially as a swinging gripper driven by an eccentric drive. The movement path of the swinging gripper relative to the storage drum or relative to the reversing drum is imposed by the eccentric drive, which executes two complete revolutions per 360° machine angle and substantially impresses onto the swinging gripper a movement path running in the shape of a loop. By the holding and lifting system disposed above storage drum and reversing drum according to this variant, the sheet trailing edge picked up from the outer surface of the storage drum is transferred in-register to the gripper system of the reversing drum. According to this variant, the holding and lifting system is moved out of the reversing drum and is constructed as a separate transfer system on the side of the printing unit for the sheet material to be turned.




In accordance with again another feature of the invention, the holding and lifting system can be constructed as a rotating pair of cylinders, on which a plurality of sucker/gripper systems are provided. By such a configuration of the holding and lifting system, the sheet trailing edge of the sheet material accommodated on the outer surface of the storage drum can be gripped early, before passing the transfer centerline, and can be transferred along a movement path from one transfer cylinder to the further transfer cylinders before it is gripped by the gripper system of the reversing drum. According to this variant, the transfer of the trailing edge of the sheet material to be turned is not carried out directly to the gripper system of the reversing drum but indirectly through the interposition of the holding and lifting system, constructed as a rotating pair of cylinders.




In accordance with again a further feature of the invention, the pair of cylinders include first and second transfer cylinders, the first transfer cylinder is adapted to pick up the trailing edge of the sheet from the outer surface of the storage drum and to transfer the trailing edge to the second transfer cylinder along a gripper path, and the second transfer cylinder is adapted to transfer the trailing edge to the gripper system of the reversing drum along the gripper path.




In accordance with a concomitant feature of the invention, the rotating cylinders of the pair of cylinders are constructed as a transfer cylinder equipped with a plurality of gripper and sucker system and, preferably, constructed as double disks, between which the sucker/gripper systems are accommodated as self-supporting bridge parts.




The method proposed according to the invention and the solution proposed according to the invention, in accordance with the variants illustrated, can preferably be used on sheet-processing multicolor rotary printing presses. If stiffer printing materials, such as board, or those materials requiring a large storage length during reversing, are processed on web-processing rotary printing presses having two and more printing units and downstream finishing or varnishing units, the use of the method proposed according to the invention and the apparatus proposed according to the invention permits smear-free in-register reversing to be achieved because the printing material to be turned is effectively protected against contact with printing-unit components accommodated in a stationary or rotating manner.




Other features that are considered as characteristic for the invention are set forth in the appended claims.




Although the invention is illustrated and described herein as embodied in an apparatus for reversing sheet material in sheet-processing machines, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.




The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a fragmentary, diagrammatic, cross-sectional view of a single-drum reversing of sheet material during the transfer of the sheet trailing edge in the area of the transfer centerline according to the prior art;





FIG. 2

is a fragmentary, diagrammatic, cross-sectional view of a single-drum reversing of sheet material with transfer of the sheet trailing edge of the sheet material advanced before the transfer centerline according to the invention;





FIG. 3

is a fragmentary, diagrammatic, cross-sectional view of a single-drum reversing with a pivotally driven swinging element according to the invention;





FIGS. 4.1

to


4


.


5


are fragmentary, diagrammatic, cross-sectional views of variants of the holding and lifting system for gripping the sheet trailing edge on the storage drum according to the invention;





FIG. 5

is a fragmentary, diagrammatic, cross-sectional view of a swinging gripper driven by a double-turn eccentric drive above reversing drum and storage drum according to the invention; and





FIG. 6

a fragmentary, diagrammatic, cross-sectional view of a pair of transfer drums disposed above reversing drum and storage drum according to the invention.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




Referring now to the figures of the drawings in detail and first, particularly to

FIG. 1

thereof, there is shown the single-drum reversing of large-format sheet material with transfer of the sheet trailing edge in the area of the transfer centerline between storage drum and reversing drum.




Sheet material


13


is conveyed from a transfer drum


16


disposed upstream of a storage drum


4


to the outer surface


5


of the storage drum


4


. There, a leading edge


14


of the sheet material


13


is gripped by a gripper system


17


of the storage drum


4


. The trailing edge


15


of the sheet material


13


is not fixed during contact with the outer surface


5


of the storage drum


4


.




The storage drum


4


according to the illustration in

FIG. 1

is an impression cylinder of a printing unit, whose transfer cylinder, which prints the upper side of the sheet material


13


, is not illustrated here. In the perfecting mode of the printing unit, the impression cylinder functions as a storage drum


4


.




Disposed downstream of the storage drum


4


is a reversing drum


1


, also referred to as a perfecting drum or a turner drum. On the circumference


2


of the reversing drum


1


, the sheet material


13


, after being turned, is picked up by the freshly printed side that previously, on the outer surface


5


of the impression cylinder functioning as a storage drum


4


, was facing the transfer cylinder of the printing unit and was freshly printed on the upper side.




Between the axis of rotation


3


of the reversing drum


1


and the axis of rotation


6


of the storage drum


4


there extends the transfer centerline


7


, at which, according to the illustration in

FIG. 1

, the sheet trailing edge


15


of the sheet material


13


is picked up by a gripper system


8


configured as tongs grippers and belonging to the reversing drum


1


. The reversing drum


1


rotates about the axis of rotation


3


in the direction of the arrow


10


, while the storage drum


4


rotates about its axis of rotation


6


in the opposite direction


11


. The position of the sheet trailing edge


15


of the sheet material


13


on the outer surface


5


of the storage drum


4


is designated by t


1E


, while the position of the leading edge


14


of the sheet material


13


is designated by t


1A


.




In the state illustrated in

FIG. 1

, the trailing edge


15


of the sheet material


13


is picked up by the gripper system


8


, constructed as tongs grippers. As a result of the rotation of the reversing drum


1


in the direction of rotation


10


, the sheet trailing edge


15


picked up by gripper faces


9


of the gripper system


8


is transferred to position t


2E


. In the process, there is a risk of the sheet leading edge


14


running into the position t


2A


, that is to say, into the gap


18


between the outer surface


5


of the storage drum


4


and the outer surface of the transfer drum


16


. Sheet material


13


, in particular, large formats that need a large storage length, are transferred into such a position, marked by designation


19


, during reversing. The position of the leading edge


14


of the sheet material


13


, reproduced in dashed lines in

FIG. 1

, is extremely disadvantageous for non-contact reversing of such a sheet and can have most disadvantageous consequences on the printing quality because the circumferential surface section of the outer surface


5


of the storage cylinder


4


, designated by the storage length corresponding to the angular range


12


, is inadequate for the storage of large-format sheet material


13


.





FIG. 2

shows single-drum reversing of sheet material with transfer of the sheet trailing edge advanced in front of the transfer centerline.




As distinct from the sheet transfer of the sheet material


13


at the transfer centerline


7


, as illustrated in

FIG. 1

, according to the method of the invention, the sheet trailing edge


15


of the sheet material


13


is gripped at a substantially earlier time by a holding and lifting system that, in all the exemplary embodiments, is disposed parallel to the recto printing guide system and, therefore, can be activated only during reversing operation. In relation to the transfer centerline


7


between the axes of rotation


3


of the reversing drum


1


and the axis of rotation


6


of the storage drum


4


, the sheet trailing edge


15


of the sheet material


13


is gripped in position t′


1E


that, in relation to the transfer centerline


7


, is displaced by the angle φ. Therefore, the sheet trailing edge of the sheet material


13


from the outer surface


5


of the storage drum


4


is, therefore, gripped earlier by a machine angle


20


. In the illustration reproduced in

FIG. 2

, the area of the sheet material


13


covers an area


12


, also identified by α, of the outer surface


5


of the storage drum


4


. The sheet trailing edge


15


lies in position t′


1E


, the sheet leading edge


14


, on the other hand, in position t′


1A


. The sheet leading edge


14


is fixed on the outer surface


5


by the gripper system


17


of the storage drum


4


, which is located in its closed position. The illustration according to

FIG. 2

makes it clear that the sheet material


13


, as compared with the positions t


1E


and t


1A


in

FIG. 1

, is gripped by the holding and lifting system at an earlier time displaced by the angle φ. This permits substantially earlier release of the sheet leading edge


14


of the sheet material


13


by the grippers


17


of the storage drum


4


. As a result, and as a result of the deflective movement of the gripper system


8


of the reversing drum


1


, configured as tongs grippers with gripper pad face


9


, it is possible, in particular, for large-format sheet material


13


to assume an extended position, identified by designation


24


, underneath the storage drum


4


without the leading edge


14


of the sheet material


13


running into the gap


18


between the outer surface


5


of the storage drum


4


and the outer surface of the transfer drum


16


. As a result of rotation of the gripper system


8


of the reversing drum


1


during the rotation of the same about the axis of rotation


3


, the sheet material


13


is substantially held in a horizontal position so that running of the sheet material


13


into the pocket


23


during the reversing action can be avoided. The closed position of the gripper system


17


of the storage drum


4


is designated by designation


21


and is maintained until the trailing edge


15


is gripped in position t′


1E


. With the method proposed according to the invention of gripping the sheet trailing edge


15


of the sheet material


13


early at a time advanced by the machine angle (φ), it is ensured that the large-format sheet material


13


to be turned, in particular, during the reversing action, passes with its leading edge in the direction of movement


25


into a position t′


2A


, in which no contact can occur with stationary or rotating components of the printing unit.





FIG. 3

shows the cylinder schematic drawing of single-drum reversing with a pivotally driven holding and lifting system.




From the transfer drum


16


, sheet material is transported to the outer surface


5


of the storage drum


4


. The upper side of the sheet material


13


held on the circumference of the storage drum


4


is printed by a transfer cylinder


30


before the sheet material


13


accommodated on the outer surface


5


of the storage drum


4


is transported to the outer surface


2


of the reversing drum


1


disposed downstream of the storage drum


4


. Disposed after the press nip between the outer surface


5


of the impression cylinder functioning as a storage drum


4


and the transfer cylinder


30


is a holding and lifting system


31


, which surrounds the outer surface


5


of the storage drum


4


with an angle of about 90°. The holding and lifting system


31


is pivotally mounted in the side walls of the non-illustrated printing press and can be set cyclically, through a swinging arm


32


, with a frictional or form-fitting connection against the outer surface


5


of the storage drum


4


. The swinging arm


32


drives the holding and lifting system


31


. The swinging arm


32


is attached by a hinge to an eccentric lever


37


that, in turn, rotates about the axis of rotation


6


of the storage drum


4


. As a result, a cyclic movement onto and away from the outer surface


5


of the storage drum


4


is impressed on the holding and lifting system


31


. The on and away movement by pivoting the entire system can be dispensed with if, as an alternative, only the individual element gripping the sheet is pressed against the impression cylinder. The direction of rotation of the storage drum


4


about the axis of rotation


6


is designated by arrow


11


, while the direction of rotation of the reversing drum


1


about the axis of rotation


3


is identified by designation


10


. To prevent, in particular, large-format sheet material


13


running into the pocket


35


between the outer surface


5


of the storage drum


4


and the outer surface of the transfer drum


16


, the pocket area can be covered at the bottom by a deflector


33


, whose side facing the storage space for sheet material


13


can be configured in a curve


34


.




Variants of holding elements on the holding and lifting system can be gathered from the illustrations of

FIGS. 4.1

to


4


.


5


.




According to the illustration in

FIG. 4.1

, the holding and lifting system


31


, mounted separately from the reversing drum


1


, includes a holding element


40


that can be set cyclically with a form-fitting or frictional connection against the outer surface


5


of the storage drum


4


. By a suction head


41


that is accommodated in the holding element


40


and can be moved at right angles to the outer surface


5


in the direction of the double arrow


42


, the trailing edge


15


of the sheet material


13


can be gripped and pushed. As a result of gripping the sheet trailing edge


15


of the sheet material


13


, its tensioning in the circumferential direction on the outer surface


5


of the storage drum


4


is possible before the trailing edge


15


can be transferred in register by a gripper system that is not illustrated here but is associated with the reversing drum


1


. At this time, the non-illustrated grippers


17


that fix the leading edge


14


of the sheet material


13


remain in their closed position


21


on the storage drum


4


.





FIG. 4.2

reveals that the sheet trailing edge


15


of the sheet material


13


can be transferred into a lifted position


45


by the suction element


41


, which can be moved in the vertical direction


42


. In the lifted position


45


, the sheet trailing edge


15


of the sheet material


13


is gripped by the gripper system


8


, which is likewise associated with the holding element


40


. The gripper system


8


, which here is constructed as a tongs-type gripper and can be pivoted about an axis


44


, picks up the tensioned and aligned sheet trailing edge


15


of the sheet material


13


so that the sheet is held very early in a gripper closure before it is then picked up by the reversing drum at the transfer centerline. To achieve tensioning of the sheet material


13


in the circumferential direction, the suction element


41


of the holding and lifting system can be pivoted in the circumferential direction


43


to tension the sheet material


13


on its circumferential surface


5


. The suction element


41


is pivoted in the circumferential direction


43


after the suction element


41


has gripped the sheet trailing edge


15


of the sheet material


13


and before the gripper system


8


has gripped the sheet.




The illustration according to

FIG. 4.3

reveals a bridge-like holding element


40


, which can be provided on a holding and lifting system


31


illustrated in FIG.


3


and accommodated in a self-supporting manner on the printing unit side walls. According to the illustration in

FIG. 4.3

, the holding element


40


is substantially U-shaped. A suction element


41


that can be displaced at right angles to the outer surface


5


of the storage drum


4


is provided in the holding element


40


. When pressure is applied to the suction element


41


, the sheet trailing edge


15


of the sheet material


13


resting on the outer surface


5


of the storage drum


4


can be transferred into a lifted position


45


—illustrated with dashes. The suction element


41


can be pivoted in the circumferential direction of the outer surface


5


of the storage drum


4


to produce tension in the sheet material


13


, before a frictional connection between U-profile, impression cylinder, and sheet is produced by pressing on the U-profile.




The illustration according to

FIG. 4.4

reveals a further variant of a holding and lifting system according to the present invention. In such a configuration of the holding element


40


, a displaceable holding finger


47


is provided, which can be displaced parallel to the outer surface


5


of the storage drum


4


in the direction of the double arrow


43


. After gripping the sheet trailing edge


15


of the sheet material


13


originally resting on the outer surface


5


of the storage drum


4


, the material


13


is transferred into the lifted position


45


by the suction element


41


. In the process, the suction element


41


performs a movement in the direction of the double arrow


42


. As soon as the sheet trailing edge


15


has reached its lifted position


45


off the outer surface


5


of the storage drum


4


, the holding finger


47


displaceably accommodated in the holding element


40


moves under the sheet trailing edge


15


in the lifted position


45


of the latter. In such a lifted position


45


, the sheet trailing edge


15


can be picked up by the gripper system associated with the reversing drum


1


.




The illustration according to

FIG. 4.5

shows a gripper


50


, which is rotatably attached at a pivot


52


and executes a pivoting movement


51


in the direction of the arrow drawn in

FIG. 4.5

. By a holding element configured in this way, it is likewise possible to grip or reach under a sheet material


13


from the storage drum


4


, the material


13


having previously been lifted by a suction element


41


, as in

FIG. 4.4

.




The illustration according to

FIG. 5

reveals a swinging gripper, driven by a double-turn eccentric drive, above reversing drum and storage drum.




The swinging gripper is constructed as a driven swinging arm


60


that is driven by an eccentric drive


61


. During a 360° machine angle, the eccentric drive


61


completes two complete revolutions so that a movement path


65


running approximately in the shape of a loop is impressed on the swinging gripper


60


. Constructed on the swinging gripper


60


is a gripper system that corresponds to that which is associated with the reversing drum


1


. In a pick-up position


63


, the swinging gripper at the position t


1′


picks up the non-illustrated sheet trailing edge of the sheet material and guides the trailing edge


15


to the outer surface


2


of the reversing drum


1


in accordance with a section of its movement path


65


. On the reversing drum


1


, the swinging gripper


60


in position


64


picks up the sheet trailing edge


15


. As a result of further rotation of the reversing drum


1


about its axis of rotation


3


(not illustrated here) in a clockwise direction with respect to the illustration, the sheet trailing edge


15


of the sheet material


13


is transported into the position t


2


, being gripped by the gripper faces


9


of the gripper system


8


, constructed as tongs-type grippers, of the reversing drum


1


. The position t


2


illustrated in

FIG. 5

corresponds to the position t


2E


from the illustration according to FIG.


2


. By the eccentric drive


31


that is accommodated on the printing unit side walls and drives the swinging gripper


60


, the sheet trailing edge


15


of sheet material


13


is gripped early, as compared with prior art solutions, before passing the transfer centerline


7


between reversing drum


1


and storage drum


4


, and is picked up in register. The section of the movement path


65


in which the sheet material


13


is transported from the position


63


on the storage drum


4


into position


64


on the reversing drum


1


is shown in continuous lines, while the return travel of the movement path


65


, serving as empty travel, is reproduced with dashed line fragments.





FIG. 6

shows a further variant of the holding and lifting system above reversing drum and storage drum configured as a pair of transfer cylinders.




According to this variant, the holding and lifting system is likewise moved out of the reversing drum


1


and disposed above reversing drum


1


and storage drum


4


. The transfer cylinders


70


and


72


each preferably have two disks disposed in the area of the printing unit side wall, between which gripper/sucker systems extend as self-supporting components. At the time t


1′


, the sheet edge


15


of the sheet material


13


according to the illustration in

FIG. 2

is picked up by the suction/gripping systems of the transfer cylinder


70


and, in accordance with the movement path


71


, is transported to the further transfer cylinder


72


and the gripper and suction systems constructed thereon. The axes of rotation of the transfer cylinder


70


and of the further transfer cylinder


72


are identified by designation


73


. The sheet material


13


lifted off the outer surface


5


of the storage drum


4


in position t


1′


is, according to the variant in

FIG. 6

, transferred indirectly, through the gripper/sucker systems of the pair of cylinders


70


,


72


, to the gripper system


8


that is associated with the reversing drum


1


. Here, too, the time at which the sheet trailing edge


15


of the sheet material


13


is gripped, according to the illustration in

FIG. 2

, is located by a machine angle φ (designation


20


) before the transfer centerline


7


between the axes of rotation


3


and


6


of reversing drum


1


and storage drum


4


. To avoid collisions between the gripper system


8


associated with the reversing drum


1


and the outer surface


5


of the storage drum


4


in the area of the cylinder gap


76


, the movement path


75


of the gripper system


8


of the reversing drum


1


extends with a path section that is set back, returning behind the circumferential surface


2


of the reversing drum


1


. After passing through the set-back path section


75


, the gripper system


8


, preferably constructed as tongs-type grippers, rotates into a position substantially impressing on the sheet material


13


a horizontal, extended position


24


(see FIG.


2


).




With the method proposed according to the invention and the apparatus proposed according to the invention in its three variants, in-register gripping and holding of the sheet trailing edge


15


far before the transfer centerline


7


between the storage drum


4


and the reversing drum


1


is ensured. By holding and lifting systems


31


,


40


,


41


;


60


,


61


;


70


,


72


disposed outside reversing drum


1


and storage drum


4


, the sheet material


13


may be gripped early, tensioned on the outer surface


5


of the storage drum


4


, removed from the storage drum


4


, and transferred in register. At the same time, in particular, early opening of the gripper system


17


fixing the sheet leading edge


14


and belonging to the storage drum


4


is possible after the in-register gripping of the sheet trailing edge


15


to ensure storage of large-format sheet material


13


underneath the storage drum


4


and to prevent the material


13


from making contact with moving stationary components in the printing unit. In the variant of the holding and lifting system according to the illustration in

FIG. 3

, the in-register driving of the holding and lifting system is carried out by producing a frictional or form-fitting connection between the holding element


40


,


41


accommodated on the moving component


31


and the outer surface


5


of the storage drum


4


. The apparatus proposed according to the invention for the cyclic tensioning, alignment, and transfer of an edge


14


or


15


of sheet material


13


can also be used at other points on the delivery path of sheet material


13


through a rotary printing press having a plurality of printing units disposed one behind another. For example, in-register transfer is required after the last printing unit before the sheet material


13


is transferred into a delivery system or a finishing unit (varnishing unit) disposed downstream. At such an interface, the apparatus proposed according to the invention and according to the variants reproduced here can be used.



Claims
  • 1. A method for reversing sheet material having edges in a sheet-processing machine having at least two printing units, which comprises:providing a gripper system on a reversing drum associated with at least one of the printing units; providing an impression cylinder operable as a storage drum in a recto/verso mode, the storage drum having a recto printing side and an impression-cylinder-side gripper system, the storage drum and the reversing drum defining a transfer centerline therebetween; and gripping, in the recto/verso mode, one of the edges of the sheet material at an angle before the transfer centerline with a holding and lifting system disposed parallel to the recto printing side of the storage drum before an edge of the sheet material fixed to the storage drum is released by the impression-cylinder-side gripper system.
  • 2. The method according to claim 1, which further comprises holding a trailing edge of the sheet material in a gripper closure before reaching the transfer centerline.
  • 3. The method according to claim 2, which further comprises producing one of a form-fitting connection and a frictional connection between the gripper closure and the impression cylinder.
  • 4. The method according to claim 1, which further comprises;placing a transfer drum upstream of the storage drum with respect to a sheet material transport direction; and releasing an edge of the sheet material fixed on a circumference of the storage drum before reaching a pocket between the storage drum and the transfer drum.
  • 5. The method according to claim 1, wherein the pocket is disposed between the storage drum and the transfer drum at a downstream side of the storage drum with respect to a sheet material transport direction.
  • 6. The method according to claim 4, which further comprises rotating the gripper system of the reversing drum to transfer the trailing edge of the sheet material into a substantially extended position.
  • 7. The method according to claim 6, wherein the sheet material assumes the substantially extended position underneath the storage drum.
  • 8. A method for reversing sheet material having edges in a sheet-processing machine having at least two printing units, which comprises:providing a gripper system on a reversing drum associated with at least one of the printing units; providing an impression cylinder operable as a storage drum in a recto/verso mode, the storage drum having a recto printing side and an impression-cylinder-side gripper system, the storage drum and the reversing drum defining a transfer centerline therebetween; gripping a given edge of the sheet material with the impression-cylinder-side gripper system; and gripping, in the recto/verso mode, a given edge of the sheet material at an angle before the transfer centerline with a holding and lifting system disposed parallel to the recto printing side of the storage drum before the given edge is released by the impression-cylinder-side gripper system.
  • 9. An apparatus for reversing sheet material having edges in a sheet-processing machine, comprising:at least two printing units, at least one of said printing units having: a reversing drum having a gripper system; an impression cylinder operable as a storage drum when recto/verso printing, said storage drum having a recto printing side, a circumference, and an impression-cylinder-side gripper system, said storage drum and said reversing drum defining a transfer centerline therebetween; a holding and lifting system disposed parallel to said recto printing side of said storage drum, said holding and lifting system adapted to: lift an edge of the sheet material off said circumference of said storage drum before said transfer centerline; and transfer the lifted edge into said gripper system of said reversing drum one of directly and along a path.
  • 10. The apparatus according to claim 9, wherein said holding and lifting system is at said storage drum and is at least one self-supporting, circulating bridge.
  • 11. The apparatus according to claim 10, wherein:said storage drum has an outer surface; and said holding and lifting system has: a driven swinging element cyclically settable against said outer surface; and a holding element for gripping a trailing edge of the sheet, said holding element disposed at a distance from said transfer centerline.
  • 12. The apparatus according to claim 11, wherein said holding element has a suction head moveable at right angles to said outer surface of said storage drum.
  • 13. The apparatus according to claim 11, wherein said holding element has a holding finger adapted to move under the trailing edge of the sheet and to lift off the trailing edge from said outer surface of said storage drum.
  • 14. The apparatus according to claim 9, including an eccentric drive, said holding and lifting system being a swinging gripper connected to and driven by said eccentric drive.
  • 15. The apparatus according to claim 14, wherein said eccentric drive executes two revolutions per 360° machine angle and impresses on said swinging gripper a loop-shaped movement path.
  • 16. The apparatus according to claim 14, wherein:said storage drum has an outer surface; and said swinging gripper transfers a trailing edge of the sheet picked up from said outer surface to said gripper system of said reversing drum.
  • 17. The apparatus according to claim 9, wherein:said holding and lifting system is a rotating pair of cylinders; and at least one of said cylinders has a sucker/gripper system.
  • 18. The apparatus according to claim 17, wherein both of said cylinders have a sucker/gripper system.
  • 19. The apparatus according to claim 18, wherein said sucker/gripper system has a plurality of at least one of suckers and grippers.
  • 20. The apparatus according to claim 17, wherein:said pair of cylinders include first and second transfer cylinders; said first transfer cylinder is adapted to pick up the trailing edge of the sheet from said outer surface of said storage drum and to transfer the trailing edge to said second transfer cylinder along a gripper path; and said second transfer cylinder is adapted to transfer the trailing edge to said gripper system of said reversing drum along said gripper path.
  • 21. The apparatus according to claim 17, wherein:said pair of cylinders are double disks; and said sucker/gripper system is disposed between said double disks as bridge parts.
  • 22. The apparatus according to claim 18, wherein:each of said pair of cylinders is a double disk; and said sucker/gripper system is disposed between said double disk as bridge parts.
  • 23. In a rotary printing press processing sheet material having edges, a printing unit comprising:an apparatus for reversing the sheet material having: a reversing drum having a gripper system; an impression cylinder operable as a storage drum when recto/verso printing, said storage drum having a recto printing side, a circumference, and an impression-cylinder-side gripper system, said storage drum and said reversing drum defining a transfer centerline therebetween; a holding and lifting system disposed parallel to said recto printing side of said storage drum, said holding and lifting system adapted to: lift an edge of the sheet material off said circumference of said storage drum before said transfer centerline; and transfer the lifted edge into said gripper system of said reversing drum one of directly and along a path.
  • 24. A rotary printing press processing sheet material having edges, comprising:at least one printing unit having an apparatus for reversing the sheet material, said reversing apparatus having: a reversing drum having a gripper system; an impression cylinder operable as a storage drum when recto/verso printing, said storage drum having a recto printing side, a circumference, and an impression-cylinder-side gripper system, said storage drum and said reversing drum defining a transfer centerline therebetween; a holding and lifting system disposed parallel to said recto printing side of said storage drum, said holding and lifting system adapted to: lift an edge of the sheet material off said circumference of said storage drum before said transfer centerline; and transfer the lifted edge into said gripper system of said reversing drum one of directly and along a path.
Priority Claims (2)
Number Date Country Kind
101 37 208 Jul 2001 DE
102 13 430 Mar 2002 DE
US Referenced Citations (16)
Number Name Date Kind
3537391 Mowry Nov 1970 A
3654861 Rudolph et al. Apr 1972 A
4015522 Preuss Apr 1977 A
4018161 Johne et al. Apr 1977 A
4165689 Giuiuzza Aug 1979 A
4821643 Wieland Apr 1989 A
4928586 Kida May 1990 A
4930414 Wirz Jun 1990 A
5335597 Helmstädter Aug 1994 A
5365846 Becker Nov 1994 A
5454312 Helmstäedter Oct 1995 A
5762333 Sugiyama et al. Jun 1998 A
6089155 Kemmerer et al. Jul 2000 A
6089157 Becker et al. Jul 2000 A
6254094 Becker et al. Jul 2001 B1
6401610 Becker et al. Jun 2002 B1
Foreign Referenced Citations (6)
Number Date Country
26 33 183 Feb 1977 DE
39 03 093 Aug 1990 DE
44 24 968 Jan 1996 DE
198 14 320 Apr 1999 DE
198 33 901 Feb 2000 DE
198 33 903 Feb 2000 DE