Printing – Printing members – Plate mountings
Patent
1988-10-24
1989-10-10
Eickholt, Eugene H.
Printing
Printing members
Plate mountings
101DIG36, 1014011, 33617, B41F 2700
Patent
active
048724076
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF INVENTION
The invention relates to a method for the mounting of a flexible printing plate on a plate cylinder for a printing machine, and an apparatus for the execution of the method. More particularly, the invention relates to a method for the mounting of a flexible printing plate on a plate cylinder for a printing machine where the surface of the printing plate is provided with adhesive coating, and where the printing plate is provided with at least one pair of register marks, in that the printing plate is aligned in accordance with the register marks by means of optical spotting devices disposed in a certain position in relation to the plate cylinder, and is secured in position of correct alignment by a holding device at a distance from the plate cylinder. The apparatus for the execution of the method comprises holding devices for at least one plate cylinder arranged to carry a printing plate with at least one pair of register marks, in that the surface of the cylinder or the back of the printing plate is provided with an adhesive coating.
Several different methods and aids are known to be used in the mounting of a flexible printing plate on a plate cylinder for so-called flexographic printing with stereotype printing plates of plastic or rubber. This form of printing is often used with raster prints with several colours, or as normal relief printing with a number of colour prints after each other.
One of the aids used is a so-called pin device, which is a mechanical aid, and which is used in the mounting of printing plates for flexo-printing when the printing task does not demand great precision.
For finer printing tasks with great precision and four-six colours, a so-called reflection mounting device is used, cf. for example European patent document no. 0,015,471.
A newer method consists of providing the printing plate with a number of holes, these being drilled or punched along one of the edges of the printing plate, said holes corresponding to pins on a transverse rail, so that the printing plate is secured at the moment of mounting, cf. for example Norwegian patent document no. 126,725, and U.S. Pat. No. 4,380,956. Where the actual mounting is concerned, this method is excellent, but it demands an extra process with very precise location of the holes in the printing plate, whereby the cost of the printing plate is considerably increased.
From the description of U.S. Pat. No. 2,711,691, there is known a printing plate mounting table which is arranged to be displaced tangentially in relation to a printing cylinder and in firm engagement therewith, in that the undersides of the table's side members are formed as toothed racks which enter into engagement with gearwheels mounted on the axle journals of the printing cylinder. The table has a head line which indicates the printing plate table's foremost limit for the extent of the print picture, said line corresponding with the start point (the line) on the printing cylinder. Above the printing cylinder there are parallel guideways for optical spotting devices, and the printing plate is provided with register marks arranged for checking the position of the printing plate on the cylinder when it has been mounted in accordance with the head line on the table. If the register check shows that the mounting of the printing plate is incorrect, one must start from the beginning again.
The known methods and devices are encumbered with a number of sources of error, and with some of the methods the result of the mounting depends on the operator's skill and knowledge of both the mounting device and the subsequent printing process, particularly if a good product is to be obtained from the printing machine in the production of multi-colour prints. The known methods are moreover very time consuming and contribute to a heavy increase in the cost of multi-colour prints.
The object of the invention is to present a method and an apparatus for the mounting of a flexible printing plate on a plate cylinder (printing cylinder), whereby the drawbacks
REFERENCES:
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patent: 4033299 (1977-07-01), Schuhmann
patent: 4055120 (1977-10-01), Kamm
patent: 4380956 (1983-04-01), Elworthy
patent: 4383760 (1983-05-01), Deter et al.
patent: 4449452 (1984-05-01), Mansell
patent: 4582768 (1986-04-01), Takeuchi et al.
patent: 4589338 (1986-05-01), Collins et al.
patent: 4611539 (1986-09-01), Ireton
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