Printing – Processes – Condition responsive
Reexamination Certificate
2000-03-31
2002-12-31
Colilla, Daniel J. (Department: 2854)
Printing
Processes
Condition responsive
C101S483000
Reexamination Certificate
active
06499401
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method and a device for absorbing torsional vibrations of a printing machine, in which at least one element absorbing torsional vibrations acts upon a gearwheel train of the printing machine.
Various types of vibrations influencing print quality occur on printing machines. Sources for the origin of vibrations are cylinder gaps or channels, sheet transfer elements and other discontinuously operating machine elements. This leads, for one, to bending vibrations in rollers and cylinders, however, also to torsional vibrations of cylinders or drums. The torsional vibrations are propagated mostly via the gearwheels of the gearwheel train and, as a rule, attain higher amplitudes with an increase in distance from the drive. Such vibrations may occur angle-synchronously or asynchronously.
Bending vibrations are controlled, on the one hand, by a sturdy form of construction and, on the other hand, by arranging damping or absorbing elements in the cylinders. For the control of torsional vibrations, the published European Patent Document EP 0 592 850 B1 discloses a device and method for providing active actuating elements, for example, motors, on the individual cylinders, in order, by measurements and controls, to activate the motors so that regulating forces which damp the vibrations are generated. This measure entails a considerable outlay in sensor technology and regulating and actuating elements. Most torsional vibrations occur angle-synchronously, vibrations of the first order occurring once and vibrations of further orders more than once per revolution. Vibrations of the first and second orders are usually the most pronounced and have to be reduced, because they may give rise, in the resonant ranges, to mackling problems which depend upon the machine speed.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method and a device for absorbing torsional vibrations of a printing machine wherein speed-dependent mackling problems are reduced as much as possible.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a method for absorbing torsional vibrations of a printing machine, wherein at least one torsional vibration-absorbing element acts upon a gearwheel train of the printing machine, which comprises determining a first characteristic form and characteristic frequency of a printing machine, and assigning to at least one shaft journal of a gearwheel, whereon highest amplitudes of the first characteristic frequency occur, a passive torsional vibration absorber modulated to reductions of the first characteristic frequency.
In accordance with another mode, the method of the invention comprises measuring the second characteristic form and characteristic frequency of a printing machine, and assigning to the at least one shaft journal of the gearwheel, whereon the highest amplitudes of the second characteristic frequency occur, a passive torsional vibration absorber modulated to the reduction of this second characteristic frequency.
In accordance with a further mode, the method of the invention includes selecting properties of the torsional vibration absorbers according to the measured values, so that absorption and damping of the torsional vibrations are achieved.
In accordance with another Aspect of the invention, there is provided a device for absorbing torsional vibrations of a printing machine, wherein at least one vibration-absorbing element is actable upon a gearwheel train of the printing machine, comprising a passive torsional vibration absorber arranged in the vicinity of the gearwheel on at least one shaft journal of cylinders or drums drivable by the gearwheel train.
In accordance with another feature of the invention, the torsional vibration absorbers are arranged at locations on the gearwheel train at which highest torsional vibration amplitudes occur.
In accordance with a further feature of the invention, in a machine having a plurality of printing units and a drive in a region of the middle of the machine, at least one torsional vibration absorber is assigned to each force transmission side.
In accordance with an added feature of the invention, the at least one torsional vibration absorber is arranged and dimensioned for reducing a first characteristic frequency.
In accordance with an additional feature of the invention, at least another torsional vibration absorber is arranged and dimensioned for reducing a second characteristic frequency.
In accordance with yet another feature of the invention, the torsional vibration absorber is a damped absorber.
In accordance with yet a further feature of the invention, the damped torsional vibration absorber is formed of at least one mass and of at least one elastomer that is inserted between a carrier and the mass, the elastomer having spring and damping properties.
In accordance with yet an added feature of the invention, the damped absorber is formed of at least one mass and of spring elements and damping elements arranged between the mass and a carrier.
In accordance with yet an additional feature of the invention, the damping elements are disposed for acting in a circumferential direction.
In accordance with still another feature of the invention, the damping elements are cylinders with pistons, the pistons being formed with respective clearances through which a damping medium is flowable.
In accordance with still a further feature of the invention, the spring elements are arranged for acting in a circumferential direction.
In accordance with still an added feature of the invention, the torsional vibration absorbers are constructed as two-stage torsional vibration absorbers for reducing first and second characteristic forms and characteristic frequencies of the printing machine.
In accordance with a concomitant feature of the invention, the device comprises first springy and damping elements arranged between a carrier and a mass, and second springy and damping elements arranged between the mass and a further mass, one of the springy and damping elements, together with the mass associated therewith, being constructed and dimensioned for reducing a first characteristic form and characteristic frequency, and the other springy and damping element, together with the mass associated therewith, being constructed and dimensioned for reducing a second characteristic form and characteristic frequency.
Thus the object of the invention is achieved, in a method of the type mentioned in the introduction hereto, in that the first characteristic form and characteristic frequency of a printing machine are determined, and in that at least one of the shaft journals of the gearwheels on which the highest amplitudes of the first characteristic frequency occur have assigned thereto a passive torsional vibration absorber modulated to the reductions of this first characteristic frequency.
The object is achieved, in a device of the type initially mentioned, in that a passive torsional vibration absorber is arranged in the vicinity of the gearwheel on at least one shaft journal of the cylinders or drums driven by the gearwheel train.
By virtue of the method according to the invention, essential causes of the mackling problems are determined in a concerted manner and are controlled simply and effectively in space and in time at the location where they occur. The first characteristic form and, if appropriate, further characteristic forms are determined, for example, by torsional vibration measurement and/or calculation. The vibrations are counteracted in their resonant ranges, i.e., when the characteristic forms and characteristic frequencies of the printing machine occur, in such a way that they are harmless to the printing process, and mackling errors can therefore no longer arise. This is performed by a corresponding modulation of the characteristic frequency of the mass of the torsional vibration absorber, the spring constant thereof and, if appropriate, the damping thereof, and also by a
Koch Oliver
Merz Michael
Colilla Daniel J.
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Locher Ralph E.
Nolan, Jr. Charles H.
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