Printing – Work supporting members – Grippers
Reexamination Certificate
1999-07-06
2001-07-24
Hilten, John S. (Department: 2854)
Printing
Work supporting members
Grippers
C101S246000, C271S277000, C271S082000
Reexamination Certificate
active
06263794
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a gripper on a sheet-transporting cylinder of a rotary printing press, in particular a pincers gripper on a reversing drum.
The published German Patent Document DE 24 14 998 A1 describes a so-called pincers gripper formed of a gripper member and a counter-gripper member. In this regard, the gripper member forms a gripper seat and the counter-gripper member forms a swivellable gripper finger disposed opposite the gripper seat. A number of these pincers grippers are distributed at intervals along the axial length of the sheet-transporting cylinder. The gripper seats are screwed to a common gripper shaft. For this purpose, the gripper shaft, at least in the region wherein the gripper seats are fixed, has a flat surface on which, during the mounting of the gripper seats, the latter can be fixed while allowing them to be displaced linearly in order to eliminate manufacturing tolerances. During the adjustment of the gripper seats, a problem exists that all of the clamping locations of the adjacently arranged gripper seats and the respective gripper fingers should lie on a common line of the clamping locations in order that the sheet to be transported can be gripped evenly without the formation of waves or undulations therein.
Due to a linear displacement of the gripper seats as in the published German Patent Document DE 24 14 998 A1, however, it becomes very difficult to set a common line for all adjacently arranged gripper devices, so that small tolerances must be accepted. Particularly for pincers grippers which transport the sheets in both recto or first-form printing, and in verso or perfector printing positions differing by more than 180°, the deviations of the clamping locations from the common line of clamping locations (the ideal line) are doubled.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a gripper with a gripper element of the gripper that is adjustable so as to minimize a deviation of clamping locations thereof from a common ideal line.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a gripper for a cylinder or a drum of a sheet-fed rotary printing press, the gripper comprising a gripper element adjustable relative to a gripper shaft carrying the gripper, the gripper element being disposed so as to be swivellable about a swivel point thereon for effecting an adjustment, the gripper element being formed with a concavely curved seating surface having a radius adapted to and smaller than the radius of the gripper shaft.
In accordance with another feature of the invention, the swivel point is disposed on or within the periphery of the gripper shaft.
In accordance with a further feature of the invention, the gripper shaft has an axis, and the swivel point is on the axis of the gripper shaft.
In accordance with an added feature of the invention, the gripper element is formed with a bore through which there extends a fixing member with adjustment play.
In accordance with an additional feature of the invention, the gripper element is cooperatively engageable with a counter-gripper element so disposed on a gripper tube coaxially surrounding the gripper shaft as to permit the counter-gripper element to swivel.
In accordance with yet another feature of the invention, the ripper includes a spring element for bracing the counter-gripper element and the gripper element cooperatively engageable therewith against one another.
In accordance with yet a further aspect of the invention, there is provided a gripper for a cylinder or a drum of a sheet-fed rotary printing press, the gripper comprising a gripper element adjustable relative to a gripper shaft carrying the gripper, the gripper element being disposed on a flat seating surface formed on the gripper shaft and being adjustable about a swivel point on the gripper element.
In accordance with a concomitant feature of the invention, the gripper element is a gripper seat, and the counter-gripper element is a gripper finger.
The invention thus offers the advantage that the quality of the take-over and feeding of the sheets to be transported can be improved in both the recto or first-form and the verso or perfector settings. A further advantage is that assembly times can be considerably reduced by a simpler method of adjusting the gripper elements.
The resistance of the shaft towards twisting and bending does not need to be reduced by recesses for mounting the gripper seat.
In a preferred embodiment of the invention, a swivelling point for the gripper elements is disposed on the axis of the gripper shaft. This feature enables the clamping points of the gripper device to be adjusted on a common ideal line.
In an advantageous embodiment, a fixing surface of the gripper seat is formed with a concave curvature having a radius of curvature smaller than the radius of the gripper shaft. This feature prevents the gripper seat from swivelling, e.g. in the screw direction, while it is fixed to the gripper shaft, i.e., the clamping line of a gripper seat, after the screw has been tightened, is aligned parallel to the gripper shaft and axis, respectively, without any further adjustment measures.
The fixing or fastening surfaces may be very rough, due to which the clamping seat on the shaft is improved. An undesired release of the gripper seat from the gripper shaft is thereby prevented.
Other features which 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 a gripper for a sheet-transporting cylinder or drum of a rotary printing press, it is nevertheless not intended to be limited to the details shown, since 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, wherein:
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Greenberg Laurence A.
Grohusky Leslie J.
Heidelberger Druckmaschinen Aktiengesellschaft
Hilten John S.
Lerner Herbert L.
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