Sheet feeding or delivering – Feeding – By means to convey sheet
Reexamination Certificate
2001-11-05
2004-01-13
Walsh, Donald P. (Department: 3653)
Sheet feeding or delivering
Feeding
By means to convey sheet
C271S267000, C414S740000, C294S104000
Reexamination Certificate
active
06676125
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a device for actuating grippers in a machine for processing sheetlike material, such as a sheet-processing rotary printing machine, wherein sheets are transported by grippers.
The published German Patent Document DE 42 00 406 A1 is concerned with a gripping device in sheet-processing machines. The grippers for a sheet-like material are fastened on a gripper operating shaft. The grippers are opened and closed simultaneously via a cam control device. By employing the teachings provided in this published German patent document, individual grippers or groups of grippers on the circumference of a sheet-guiding cylinder are activated independently of one another. A control device which activates the grippers is provided for this purpose, the control device including at least one sensor, an opening and/or closing mechanism for the grippers and a computer. The control device actuates the opening and/or closing mechanisms at a prescribed machine position or setting. The sensors used in this heretofore known construction are angle-of-rotation sensors or paper-position sensors, in order to detect either the position of the cylinder or the position of the sheet-like material, and then to actuate the opening and closing mechanism.
The published European Patent Document EP 0 775 576 B1 is concerned with a gripper control device for a cyclically oscillatingly driven pre-gripper for transporting individual sheets in a sheet-fed printing machine. This published document discloses a gripper control device for a cyclically oscillatingly driven pre-gripper accommodated at a free end of a rocking lever pivotable about a pivot pin fixed to a frame, the pre-gripper having at least one sheet gripper. The sheet gripper is forcibly movable about a joint pin aligned parallel to the pivot pin, by cams for closing and opening purposes, as the sheets are received and transferred. One of the cams revolves with a single revolution and, in the course thereof, pivots the other cam, which is pivotably mounted on a stationary roller lever. The position of the cams determines the points in time at which the gripper closes and opens.
A switching mechanism is provided in order to fix the pivotable cam, this cam having a gripper-closing region and a gripper-opening region. The gripper-closing region is additionally provided with a gripper-opening region, the additionally arranged gripper-opening region having assigned thereto, for compensation purposes, an additional gripper-closing region on the single-revolution cam.
In order to produce closing or opening movements of sheet-gripping grippers, use has been made heretofore, in particular, of mechanical cam mechanisms, and occasionally also coupler mechanisms. These drives have the disadvantage that usually a fixed mechanical coupling is provided for the main machine drive, and that it is not possible to change the movement due to the kinematic dimensioning. This means that the movement cannot readily be adapted during operation to changed boundary conditions, e.g., a different printing-material thickness. In the case of double-sheet detection, mechanical barriers prevent the grippers from closing, so that the double-sheet formation cannot be gripped and conveyed into the machine. This improvement or solution, however, involves great mechanical outlay in order to realize the basic functions such as gripper control, paper-thickness adaptation and defective-sheet detection. The entire “pre-gripper” system is subjected to disruptive force action during the gripper actuation, and this solution also causes the machine to be subjected to a retroactive torque effect. The system used for closing the grippers during double-sheet detection requires long reaction times and takes up installation space in printing units. Furthermore, using the aforementioned improvements or solutions for producing the closing and opening movements of sheet-gripping grippers, movement can only be introduced at the ends of the gripper shaft.
SUMMARY OF THE INVENTION
In view of improvements or solutions heretofore known from the prior art, and of the technical problems which are presented, it is an object of the invention to provide a gripper control which requires only low mechanical outlay, performs the functions required of the gripper control and has as little effect as possible on the movement of a pre-gripper.
With the foregoing and other objects in view, there is provided, in accordance with a first aspect of the invention, a pre-gripper driving device for a pre-gripper cyclically driven oscillatingly and serving for transporting individual sheets in a sheet-processing machine, comprising sheet grippers disposed at a free end of a rocking lever pivotable about a pivot pin fixed to a frame, the sheet grippers being movable relative to a gripper support about a gripper shaft aligned parallel to the pivot pin, for closing and opening the sheet grippers, and an activatable and regulatable drive for producing the movement of the grippers, the drive, on one hand, being connected to the sheet grippers and, on the other hand, being supported on one of the rocking lever and the frame.
In accordance with another feature of the invention, the drive is actable centrally on the gripper shaft which serves for pivotably accommodating the sheet grippers.
In accordance with a further feature of the invention, the drive is introducible into both ends of the gripper shaft simultaneously.
In accordance with an added feature of the invention, the drive is realized as a linear drive with an extensible actuating element accommodated on the sheet grippers, respectively, at an articulation point thereon.
In accordance with an additional feature of the invention, the drive is realized as a rotary drive, serving for acting at least indirectly on the gripper shaft.
In accordance with yet another feature of the invention, the drive is realized as an actuating motor.
In accordance with yet a further feature of the invention, the actuating motor is operatively engageable with the gripper shaft via a rack and pinion.
In accordance with yet an added feature of the invention, the drive is constructed as a piezoelectric actuator.
In accordance with yet an additional feature of the invention, the drive is constructed as a piston/cylinder unit subjectible to a pressure medium.
In accordance with still another feature of the invention, the drive is a linear drive having a line of action running parallel to a direction of movement of a coupling link-mounted point of articulation of the linear drive on the pre-gripper lever.
In accordance with still a further feature of the invention, in closed condition of the sheet gripper, the point of articulation is located at least approximately on a connecting line between the gripper shaft and a point of rotation of the pre-gripper lever.
In accordance with still a further feature of the invention, in closed condition of the sheet gripper, the point of articulation is located between the gripper shaft and the pivot pin of the pre-gripper lever.
In accordance with still an added feature of the invention, a point of articulation of the drive coincides, on the frame, with the pivot point of the pre-gripper lever.
In accordance with still an additional feature of the invention, a point of articulation of the drive is disposed on the frame, and an actuating lever of the drive has a joint.
In accordance with a second aspect of the invention, there is provided a printing unit having a pre-gripper driving device for a pre-gripper cyclically driven oscillatingly and serving for transporting individual sheets in a sheet-processing machine, comprising sheet grippers disposed at a free end of a rocking lever pivotable about a pivot pin fixed to a frame, the sheet grippers being movable relative to a gripper support about a gripper shaft aligned parallel to the pivot pin, for closing and opening the sheet grippers, and an activatable and regulatable drive for producing the movement of the grippers, the drive, on one hand, being
Maass Jürgen
Müller Volker
Schaeffer Thomas
Thünker Norbert
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Joerger Kaitlin
Locher Ralph E.
Stemer Werner H.
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