Printing – Print plate feeding or delivering
Reexamination Certificate
2000-03-31
2003-02-11
Evanisko, Leslie J. (Department: 2854)
Printing
Print plate feeding or delivering
C101S415100, C101S216000
Reexamination Certificate
active
06516723
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to a printing-plate changer assembly for making ready and feeding printing plates to a plate cylinder of a printing unit, the assembly including a printing-plate changer located upline or in front of the printing unit, in a position for feeding the printing plates, and being articulatedly connected to the printing unit by at least two four-bar linkages so that it is pivotable upwardly into a swung-away position for servicing work.
A printing-plate changer of the foregoing general type has become known heretofore from the published European Patent Document EP 0 433 798 A2. This printing-plate changer is fixed to a lower portion of a printing unit guard and is pivotable upwardly together with the latter by two four-bar linkages. A disadvantage of this printing-plate changer is that a locking mechanism is required for the aforementioned positions, which must be locked and unlocked, respectively, separately by mechanical or electrical control or by hand. This applies particularly to the swung-away position located at the top, because the performance of service work calls for a high level of safety. In addition, the action of pivoting into the upper end position requires an expenditure of a great amount of force.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a printing-plate changer assembly of the type described at the introduction hereto that is held securely and automatically in the positions thereof and is easily bringable into the swung-away position.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a printing-plate changer assembly for making-ready and feeding printing plates to a plate cylinder of a printing unit, the assembly including a printing-plate changer located upline of the printing unit, in a position for feeding the printing plates, and being articulatedly connected to the printing unit by at least two four-bar linkages so that it is pivotable upwardly into a swung-away position for servicing work, comprising at least one element articulatedly connected with the printing unit and with the printing-plate changer so that it holds the printing-plate changer in both the feeding and the swung-away positions and assists the pivoting movement.
In accordance with another feature of the invention, the at least one element is formed as a sprung element and is articulated and aligned offset with respect to the articulations of the four-bar linkages, so that it urges the printing-plate changer downwardly into the position for feeding the printing plates and upwardly into the swung-away position, as well as away from a given pivoting angle.
In accordance with a further feature of the invention, a plurality of the elements are disposed on both sides of the printing-plate changer.
In accordance with an added feature of the invention, the at least one element is a gas pressure spring.
In accordance with an additional feature of the invention, the printing-plate changer serves to replace a printing unit guard, and the printing unit is accessible for substantially all servicing work due to the pivoting action.
In accordance with yet another feature of the invention, the printing-plate changer assembly includes an active element for performing the pivoting movement.
In accordance with yet a further feature of the invention, the printing-plate changer assembly includes two upper levers and two lower levers for providing articulation.
In accordance with yet an added feature of the invention, the printing-plate changer has a substantially two-dimensional extent, and the assembly includes a plurality of articulations formed so that the printing-plate changer completes the pivoting in a semicircle lying in the plane of the two-dimensional extent of the printing-plate changer.
In accordance with yet an additional feature of the invention, the printing-plate changer has a substantially two-dimensional extent, and the assembly includes a plurality of articulations formed so that the printing-plate changer completes the pivoting in a semicircle lying perpendicularly to the plane of the two-dimensional extent of the printing-plate changer.
In accordance with still another feature of the invention, the printing-plate changer assembly includes a synchronization shaft for connecting at least one lever pair to another at an articulation.
In accordance with still a further feature of the invention, the printing-plate changer is also constructed for holding the printing plates after they have been used.
In accordance with still an added feature of the invention, power is introducible into the printing-plate changer in a region of the axes of rotation.
In accordance with still an additional feature of the invention, power is introducible via at least one clutch.
In accordance with an alternative feature of the invention, power is introducible via gearwheels intermeshing in a closed state.
In accordance with another feature of the invention, the printing-plate changer assembly includes a locking device for securing the intermeshing of the gearwheels.
In accordance with a further feature of the invention, the printing-plate changer assembly includes a printing-plate conveying device disposed in the printing-plate changer.
In accordance with an added feature of the invention, the printing-plate conveying device has a pressure roller and a back-pressure roller which are pressable against one another by spring force, with a printing plate included therebetween.
In accordance with an additional feature of the invention, the printing-plate changer assembly includes a motor for driving the printing-plate conveying device, the motor being disposed on the printing unit.
In accordance with a concomitant feature of the invention, the printing-plate conveying device has a free wheel for permitting a printing plate to be drawn in by rotation of the plate cylinder.
Thus, the object is achieved in that at least one element is constructed and articulated on the printing unit and printing-plate changer so that it holds the printing-plate changer in both positions and assists the pivoting movement.
Printing-plate changers in this sense can be automatic, semi-automatic or also make-ready devices for improved manual feeding.
Due to the configuration according to the invention of the printing-plate changer, a secure hold in all positions is achieved. In particular, assurance is provided that the printing-plate changer remains in the upper swung-away position thereof even when vibration occurs. As a result, in particular, work safety during servicing work is increased in a simple and reliable manner, and there is no requirement for a separate locking device with separate locking and/or unlocking, particularly in the swung-away position. Due to the assistance provided to the pivoting movement, the printing-plate changer according to the invention is particularly suitable for manual operation. However, performing the pivoting movement automatically is also possible, of course. In this case, a less powerful drive is required. The printing-plate changer and the pivoting mechanism are of compact construction, and a synchronous movement sequence and weight compensation are possible in a simple manner.
One embodiment of the invention provides for the element to be formed as a sprung element and to be articulated and aligned offset with respect to the articulations of the four-bar linkages so that it urges the printing-plate changer downwardly into the position for feeding the printing plates and upwardly in the swung-away position, as well as from a specific pivoting angle. The elements can be arranged on both sides of the printing-plate changer. The sprung element is expediently a gas pressure spring or strut, because this offers the additional advantage that the movement sequence is damped. This is particularly advantageous when the printing-plate changer is pivoted into the lower position thereof, because this movement sequence is assisted by the weight, and the printin
Evanisko Leslie J.
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Locher Ralph E.
Stemer Werner H.
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