Printing – Multicolor – Rotary machines
Reexamination Certificate
2002-03-12
2004-03-09
Nolan, Jr., Charles H. (Department: 2854)
Printing
Multicolor
Rotary machines
C101S484000, C101S485000
Reexamination Certificate
active
06701836
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method of synchronizing a printing-machine drive system having a plurality of drives with drive motors, to which local drive control units and a central operating and control unit with a data processing system are assigned, components of the data processing system being connected so as to communicate with one another, and the drive motors being operated decentrally via the respectively assigned drive control units by prescribed drive data. The invention also relates to a printing machine for implementing the foregoing method.
A method for driving a plurality of motors of a drive system, which serves for keeping the motors synchronized, has become known heretofore. In general, such drive systems are subject to a problem of keeping a relatively large number of drives synchronized with regard to the prescription of a nominal or desired angular value. In particular, in the case of a drive system of a printing machine with drives for each printing stage and printing ink, respectively, it is necessary to keep the drive motors of the various drives synchronized in order to be able to realize good printed results. Because of the different specifications of the drives, in the printing machine, it must first be possible for various types of drive motors to be used in the drives and, secondly, it is necessary to provide various types of processors for the drive controls of the drives.
U.S. Pat. No. 5,615,609 describes a drive system and a method of controlling the data acquisition in a printing machine for corrugated board, having a plurality of drives which permit the use of d.c.-motors. In this regard, a main drive control for controlling the motor speed is coupled electronically with the main drive. A main drive timing or clock generator generates an output clock which depends upon the rotational movement of the main drive. A follower drive motor is coupled electronically with a follower drive control in order to control the speed of the follower drive motor with respect to the main drive motor. A follower drive clock generator generates an output clock as a function of the rotational movement of the follower drive of the printing machine. A controller is set up to receive the output clock signals from the main and the follower drive clocks, and processes the main and the follower drive clocks in order, in this respect, to generate control commands and transmit them to the follower drive control, so that the follower drives are set as a function of the main drive, in order to achieve synchronous running of the main and the follower drive motors.
The disadvantages of this system and method consist primarily in that the controls of the follower drives depend upon the operation of the main drive. This dependence calls for the running of the follower drives always to react with a delay to the prescription of the main drive. Differences between the clock generators and also in computing accuracy and computing speed of the drive controls cannot be compensated for internally. Furthermore, the synchronous running of the drive motors is set exclusively based upon the clock signals from the clock generators assigned to the motors, so that relatively large differences between the operating values of the d.c.-motors and the desired values of the central control, which exceed one or more sampling intervals, cannot be corrected by the heretofore known synchronous control.
A further disadvantage is that the transmission of the main drive clock to the follower drive controls takes place over electronic paths of different lengths, generally with one or more electronic modules being interposed, so that different transmission times also occur. Compensation for such differences in an electronic conductor arrangement which is physically extended and exposed to interference is costly and susceptible to error.
It is also disadvantageous that, when various types of drive motors are used on the printing machine and are controlled with different processors, the processors can have different clock frequencies, different computing accuracies with regard to the number of decimal places and roundings, respectively, and different sampling times, at which the motor positions are checked. When these various types of drive motors interact with different processors, after a given time, a drift in the synchronous running of the drive motors is produced, which is set due to the aforedescribed differences in the components, and effects an angular difference of the drive motors, which cannot be detected by the drive control itself. Even if this angular difference should not actually lead to collisions between mechanical parts, it nevertheless causes considerable loss in terms of quality in the print.
Furthermore, from interface technology, drive controls for machine drives have become known heretofore wherein the data processing systems of the drives are connected together in data loops. The company periodical SERCOS-IEC61491, EN 61491 discloses a drive system wherein, respectively, a plurality of drive axes can be connected together in a data loop as a drive group. In each data loop, the prescription of drive values and control commands is updated in a sampling and updating cycle successively in each of the connected drives, which means that the updating of the desired or nominal values of each drive is carried out almost simultaneously by processing the same command, test and computing steps.
In this system, it has proven to be disadvantageous for a large amount of data to be produced between the drives and the control units thereof, and also between the drive control units and the central operating and control unit, because, due to the accuracy requirement with regard to synchronous running, in particular when used in a printing machine having a plurality of drives, the values have to be measured simultaneously in each individual drive, and the command prescriptions thereof have to be processed simultaneously. In the disclosed data loops, therefore, complicated and costly components are needed for the corresponding data connections, such as the data bus between the control units, and corresponding integrated circuits with a high capacity.
Furthermore, in this system, it is disadvantageous that the processing of a command and/or sampling cycle is successively performed from drive to drive and can therefore vary in time between the drive groups, respectively, connected in separate data loops. Only after a cycle has been completed are all the drives in the data loop coordinated synchronously with one another, the coordination of the data loops of the various drive groups having to be performed centrally.
In order to avoid inaccuracies or disruption of the synchronous running in all of the drives, there is therefore a need for costly data processing systems, including the data processing programs provided for this purpose, which can manage the large throughput of data and take into account the required, extremely low cycle and sampling times, respectively.
SUMMARY OF THE INVENTION
Consequently, it is an object of the invention to improve the synchronization of a plurality of drive motors of a printing-machine drive system, or the like.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a a method of synchronizing a printing-machine drive system having a plurality of drives with drive motors, to which local drive control units and a central operating and control unit with a data processing system are assigned, components of the data processing system being connected so as to communicate with one another, and the drive motors being operated decentrally by prescribed drive data via the respectively assigned drive control units, which comprises, calculating, with at least one component of the data processing system of one of the drive control units, respective drive data as a function of the computing operations required in the remaining components of the data processing system, and, in a
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Mayback Gregory L.
Nolan, Jr. Charles H.
Stemer Werner H.
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