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Characterization, determination of a characteristic number and selection of suitable dressings on cylinders of a printing press

a technology of printing press and characteristic number, which is applied in the direction of printing press, rotary press, printing press, etc., can solve the problems of different surface velocities, slippage in the nip, change in surface pressure and roll-off, etc., and achieve the effect of facilitating a definite selection of dressings and reducing distance to the center of rotation

Inactive Publication Date: 2006-03-09
SCHASCHEK KARL ERICH ALBERT +4
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009] The advantages which can be obtained by the present invention reside, in particular, in that a quantitative description of the dressings in respect to their conveying, or roll-off behavior is made possible, and that the characterization created in this way is independent of the geometry of a measuring device, as well as being independent of the geometry of a print unit. The characteristic number used for characterizing the dressing is corrected for the specific geometries and can be alternatingly used with a measuring device or the print unit. The description is no longer purely qualitatively usable, for example positively conveying, negatively conveying, but is also quantitatively usable.
[0010] By use of the method for characterizing a dressing by the use of a characteristic number in accordance with the present invention, an unequivocably defined language for the producer of dressings and the designer of the printing press is created which, on the one hand, permits a tailor-made construction of the printing press in connection with a desired, pre-selected dressing, and on the other hand facilitates a definite selection of a dressing for a pre-selected configuration of a printing press. Both can already be clarified at the outset, so that an expensive test program, which otherwise must be performed at the printing press for the special configuration and for each type of dressing, can be omitted.
[0011] It is therefore an advantageous solution to select a dressing for a given pair of cylinders in such a way that, in the course of a compression of the dressing, because of an incompressible component, the dressing is extended to such a degree that the reduced distance to the center of rotation of the cylinder supporting the dressing is compensated. Such a requirement can be determined by utilization of the method in accordance with the present invention, and an appropriate dressing can be selected.
[0012] In an alternate approach, it is therefore advantageous to select the geometry of the printing group for a special, given dressing in such a way that in an area of variable compression, the roll-off behavior of the dressing does not depend, or only slightly depends on the dressing compression.
[0015] The possibility of configuring a printing group, which is optimized in respect to its roll-off behavior, is also advantageous. For example, a transfer cylinder of double circumference can be embodied with a dressing with a characteristic number α of 0.989 to 0.999, while a transfer cylinder of single circumference with a dressing with a characteristic number α of 0.980 to 0.995 can be used, if it cooperates with a counter-pressure cylinder of substantially the same circumference. The cited characteristic numbers α must be observed for a relative compression, at least in a range relevant to actual use.

Problems solved by technology

In the course of the soft surface roller's rolling off on the cooperating hard roller, this surface deformation leads to changes in the surface pressure and in the roll-off.
With rollers which are driven mechanically or which are electronically synchronized, this can lead to different surface velocities as a function of the material used and of the compression, and therefore to slippage in the nip defined as the area of contact between the two rollers.
The slippage generated in this manner results in a tangential force component because of friction, and therefore a reduced print quality which may be due to pushing or blurring, interference with the transfer of power, as well as a reduced service life of printing formes, or dressings.

Method used

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  • Characterization, determination of a characteristic number and selection of suitable dressings on cylinders of a printing press
  • Characterization, determination of a characteristic number and selection of suitable dressings on cylinders of a printing press
  • Characterization, determination of a characteristic number and selection of suitable dressings on cylinders of a printing press

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third embodiment

[0064] In a third embodiment, which is not specifically represented, the forme cylinders 01, 12 are embodied as cylinders 01, 12 of single circumference with effective diameters DwPZ between 150 and 190 mm, and the transfer cylinders 02, 11 are embodied as cylinders 02, 11 of double circumference with effective diameters DwGZ between 260 and 400 mm, and in particular between 280 to 350 mm. The transfer cylinder 02, 11 has at least one dressing 06 with a characterizing number α of 0.987 to 1.000, and in particular of 0.997 to 1.000. The number of revolutions ratio Ireal is again preferably selected in such a way that, in case of a variation of the compression S, or of the relative compression S*, at least within the above mentioned range for the relative compression S*, of the appropriate cylinder pairing, it deviates by maximally 0.002, and in particular by 0.001, from 1.000 / n, thus with n=2, i.e. 0.002, and in particular 0.001, from 0.500.

[0065] A printing group 14 is represented ...

first embodiment

[0066] In a first embodiment in FIG. 7, the forme cylinder 01, the transfer cylinder 02 and the satellite cylinder 16 are embodied as cylinders of double circumference with effective diameters DwGZ, DwPZ between 260 and 400 mm, and in particular between 280 to 350 mm. The transfer cylinder 02 has at least one dressing with a characterizing number α of 0.990 to 0.990, and in particular of 0.993 to 0.997. A largely slippage-free roll-off, or a drive of the cylinders 01, 02, 16 largely without a moment transfer, is assured by this configuration.

second embodiment

[0067] In a second embodiment for FIG. 7 or 8, the forme cylinder 01, transfer cylinder 02 and satellite cylinder 16, are embodied as cylinders 01, 02, 16 of simple diameter, i.e. with a circumference of substantially one vertical printed page, in particular a newspaper page. They are embodied with effective diameters DwGZ, DwPZ between 120 and 180 mm, and in particular between 130 to 170 mm. The transfer cylinder 02 has at least one dressing with a characterizing number α of 0.990 to 0.990, and in particular of 0.993 to 0.997.

[0068] In a third embodiment, which is not specifically represented, for FIG. 7 or 8, the forme cylinder 01 is embodied as a cylinder 01 of single circumference with an effective diameter DwPZ between 120 and 180 mm, and in particular between 130 to 170 mm, and the transfer cylinder 02, as well as the satellite cylinder 16 as cylinders 02, 16 of double circumference with effective diameters DwGZ, DwSZ between 260 mm and 350 mm, and in particular between 280 mm...

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Abstract

In connection with a method for characterization of a layer, a method and a device for determining a characteristic number, as well as a method for selecting a suitable dressing on rollers, or suitable geomtries of rollers of a printing press, a characterizing number for characterizing a layer is formed, or employed, which characterizes the roll-off behavior independently of a measuring device or an application in a particular printing group.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a division of U.S. application Ser. No. 10 / 398,506, filed Apr. 23, 2004. That application is a filing under 35 U.S.C. 371 of PCT / DE02 / 03142 filed Aug. 28, 2002, published as WO 03 / 086760 on Oct. 23, 2003 and which claims the benefit of U.S. Provisional Application No. 60 / 371,411, filed Apr. 11, 2002, the disclosures of which are expressly incorporated herein by reference.FIELD OF THE INVENTION [0002] The present invention is directed to a method for characterization, to a method and to a device for determining a characteristic number, as well as to methods for selecting suitable dressings on rollers, or suitable geometries of rollers of a printing press. BACKGROUND OF THE INVENTION [0003] In printing presses, and in particular in rotary printing presses, ink is applied between one or several rollers of an ink unit, between the ink unit and printing group cylinders, possibly between printing group cylinders, and from ...

Claims

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Application Information

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IPC IPC(8): B41F27/06B41F13/193B41F30/04B41N10/04
CPCB41F13/193Y10T428/24992B41N10/04B41F30/04
Inventor SCHASCHEK, KARL ERICH ALBERTCHRISTEL, RALFHAHN, OLIVER FRANKMASUCH, BERND KURTWESCHENFELDER, KURT JOHANNES
Owner SCHASCHEK KARL ERICH ALBERT