Sheet feeding or delivering – Feeding – By means to convey sheet
Reexamination Certificate
2001-11-30
2003-07-15
Walsh, Donald P. (Department: 3651)
Sheet feeding or delivering
Feeding
By means to convey sheet
C271S003210, C271S264000, C271S275000
Reexamination Certificate
active
06592121
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to an apparatus for synchronizing transfers of a sheet material, such as sheets of paper or board to be printed during their transport through sheet-processing machines such as rotary printing machines.
Published, Non-Prosecuted German Patent Application DT 25 01 963 A1 relates to a gripper carriage drive. In a printing machine having a feeder and a deliverer unit, the sheet to be printed is preferably guided on horizontal paths in the grip of a gripper. The gripper carriages in each case carrying the individual sheets function as armatures with the printing-unit and return running rails which are disposed on both sides in the side walls of the printing machine, form an endless belt and function as stators. Together with the printing-unit and return running rail functioning as stators, the gripper carriages each form a linear motor connected to a control device. This solution constitutes the coupling of machine groups to linear drives that are guided on a closed circular path.
During the conveyance of articles, such as sheets to be printed, through the printing units of multicolor rotary printing machines, the articles are transferred from one transport system to the following transport system at the interfaces between the transport systems used there. In the case of rotary printing machines, the sheet material is transferred from one cylinder to the next by the gripper systems of the two cylinders holding the sheet simultaneously for a brief moment. The preceding system is then opened and the sheet material is still held only by the following system. The transfer necessitates mechanical components inter-engaging. The mechanical coupling of the cylinders via the gear train ensures the accurate-register transfer of the sheet material and the collision-free dipping action of gripper bars in one another.
However, if the drives of the cylinders of printing units in rotary printing machines are configured as individual drives, so that there is no longer any mechanical coupling of the cylinders to the gear train, in the event of a failure of a drive, caused by faults in the electronic control and motor, it is no longer ensured that the gripper bars gripping the sheet material will dip into one another without collision. The same problem arises when linear units are used for the sheet transport, and the sheet material is held and conveyed by gripper bars that are driven on one or both sides by linear motors. The sheet material is then transferred by the linearly moved gripper bar to the respective next cylinder. If components of the individual drive fail here, it is also necessary to ensure that gripper bars and cylinders do not collide with one another. Published, Non-Prosecuted German Patent Application DT 25 01 963 A1, mentioned at the beginning, discloses a machine concept in which linearly driven gripper bars transport paper sheets through a rotary printing machine with printing units disposed one behind another. In this solution, machine groups—gripper carriages here—are coupled by linear drives that are guided on a closed circular path.
The configuration does not have any mechanical collision safeguard to prevent the gripper bars being drawn into the printing units. Transfer units based on linear motors, which implement the transfer of the sheet material or the transfer of sheet material from and to printing-unit cylinders, have hitherto been configured without any collision safeguard. This results in an availability deficit in the event of faults, since the remaining components of the rotary printing machine are in this case not protected against collision of mechanical parts.
One previously known possible solution to the technical problem indicated is to synchronize the gripper bars that are fastened to chains with the cylinders. This is achieved by gripper bars fixed to chains being fixed by prismatic elements between impression cylinder and blanket cylinder.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an apparatus for synchronizing transfers of sheet material which overcomes the above-mentioned disadvantages of the prior art devices of this general type, which ensures the collision-free entry of linearly driven holding devices conveying the sheet material, and also the collision-free passage of the holding devices, along the press nip and to prevent damage to cylinders processing the sheet material.
With the foregoing and other objects in view there is provided, in accordance with the invention, an apparatus for transporting a sheet material in a sheet-processing machine having individual stations with cylinders. The apparatus contains a transport system for the sheet material having drives driven independently of the cylinders of the individual stations processing the sheet material in the sheet-processing machine; and at least one cylinder-coupled collision safeguard functioning as a synchronization mechanization bringing about a synchronization of the transport system conveying the sheet material and the cylinders.
By the solution proposed according to the invention, both the maintenance of the register accuracy and the avoidance of collisions may be implemented by various elements. While the maintenance of register is substantially achieved by the use of mutually synchronized electronically controlled drives, the mechanical elements which are proposed in accordance with the invention and are mechanically coupled to the cylinders accommodated, for example, in the printing unit of a rotary printing machine, ensure protection against collision of moving machine parts. According to the solution proposed in accordance with the invention, the coupler drives monitoring a small movement area with regard to the collision are assisted by mechanical safety elements which can be retracted, so that the collision-free entry of the gripper bars conveying the sheet material into the printing area is ensured in the case of advanced or retarded gripper bars (during disrupted operation).
With the solution proposed in accordance with the invention, it is further possible, in the case of linearly driven gripper bars which are merely used to transfer the sheet between the printing unit and the deliverer, to ensure collision-free operation, in particular prevent damage to the expensive and complicatedly produced cylinders, in the event of failures.
In order to rule out the situation where the complicatedly and expensively produced cylinders in the printing unit of a rotary printing machine are damaged in the event of fault by the asynchronous entry of units conveying the sheet material, it is ensured that the elements preventing the collision in the printing unit of a rotary printing machine are coupled precisely to the cylinders to be protected.
In a development of the idea according to the invention, as a collision safeguard in printing units of rotary printing machines, synchronization mechanisms are used whose output movement is coupled to the position of a transverse cylinder and/or a cylinder carrying the sheet material. The cylinders substantially to be protected against collision with gripper bars in the printing unit are the blanket cylinder that transfers the ink to the surface of the sheet material and also the paper-carrying impression cylinder supporting the sheet material in the printing unit of a rotary printing machine. If, in the event of turner devices being used in rotary printing machines, anti-smear coatings are applied to the impression cylinder, the protection of its surface finished in such a way is all the more important.
According to a further aspect of the solution proposed in accordance with the invention, an output element of the synchronization mechanism functioning as a collision safeguard is driven at a higher speed as compared with the tangential speed of the linear element conveying the sheet material. In this way, before the gripper element gripping the sheet material dips into the press nip with the tangential speed, it is possible to achieve the
Frank Hendrik
Greive Martin
Schaeffer Thomas
Bower Kenneth W
Heidelberger Druckmaschinen AG
Locher Ralph E.
Walsh Donald P.
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