DE2306290A1 - METHOD OF PREPARING A PRINTING PLATE -FORM FOR ACCURATE REGISTER APPLICATION TO A PRINTING MACHINE - Google Patents

Description

WR GRACE & CO., 3 Hanover Square, New York , NY (V.St.A.)

Method of preparing a printing plate or form for accurate registration on a printing press

The invention relates to a method of preparation a printing plate for precise registration on a press or printing machine.

It is known that printing plates can be made using photohardenable compositions. Eijt example one such method is disclosed in U.S. Patent 3,615,450 described. When preparing such plates, specifically using a thin metal plate, for example Made of aluminum, steel or the like. As a support, there is a need to convert the printing areas into with respect to the areas of engagement with the printing plate carrier, the so-called. Saddle or pressure foundation, (saddle) to align precisely before inserting it into a printing machine. The invention provides a method for preparing flexible thin printing plates, in particular

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those with a thin layer support or a thin ... Metal support plate for direct attachment in a perfectly aligned position to the printing plate carrier of the Printing press by precisely trimming the edges of the same and additional punching of slots for engaging the Printing plate carrier along opposite bent over Ends of the plate. -:

According to the US-PS mentioned, a printing plate is prepared by applying a light-curable material through a slide or exposed through a transparent film, and according to of the invention are in the non-printing areas of the slide is provided at the same time register areas, so that during exposure the register b, a part of the non-printing, light-cured areas of the printing plate will. These register areas are related to the printing Area carefully aligned and, as the following shows, allow the significant difficulties the alignment of the areas of attachment of the metallic Eliminate layer support on the printing plate support.

When a printing plate is prepared in the manner described is, the developed plate is ready for the further ■ process steps of shearing, punching and bending.

According to the method according to the invention in the non-printing Areas of a printing plate with a thin metallic substrate register areas are provided which The pressure plate with the register areas is attached in a fixed, fixed position, sheared along its width, sheared along opposite ends and punched with slots for engagement with the printing plate support provided, and. the edges with the engagement

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slots for the printing plate carrier are bent over. In a preferred method according to the invention, the plate is made simultaneously with the bending in the longitudinal direction stretched, which prevents the bent cantert from springing back into its original position.

The method according to the invention is explained in more detail below with reference to the drawing.

Fig. 1 illustrates schematically in perspective Representation of the production of the register and print areas by exposing a light-curable polymer is at a layer through a slide;

Pig. Fig. 2 is a cross section showing the setting of register areas in a specified one Position;

Figure 3 similarly illustrates shearing along the length of the plate;

FIG. K is a section along a plane at right angles to the sectional plane of FIG. 2 to illustrate the avoidance of edges and the punching of engagement slots for the printing plate carrier along opposite front ends of the plate;

Fig. 5 similarly illustrates the bending of the opposite end faces of the plate which, if desired, may be followed by the operation of Fig. H; and

Fig. 6 is a top perspective view of the finished

in
machined plate for attachment to the printing

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plate carrier of a printing press ready position.

According to the invention, as the drawing shows, register areas which are initially aligned with respect to the printing area of the printing plate are provided. As in As shown in Fig. 1, a pressure plate 10 has a support plate or a substrate 12 made of metal with a light-curable polymer layer 14 with a printing Area 16 and register areas 18. The printing ones Areas and the register areas are generated by the layer 14 through a transparent film 20 with printing Areas 22 and register areas 24 using a light source 26, for example UV light, exposed is, whereby the relevant areas 16 and 18 of the photohardenable polymer are cured, and the uncured polymer is eliminated. (See, for example, the referenced U.S. Patent).

After the plate has been exposed to light and any post-treatment for developing it, the printing plate TO is subjected to the preliminary work step shown in FIG. The printing plate 10 with the metal substrate 12 is placed on a vacuum table 30 or other suitable base and aligned thereon using alignment devices 28 which cooperate with the register areas 18. The printing plate is xn by any suitable means, for example by from a suitable source through a line 3k with vacuum acted upon vacuum channels 32. ₉ spring position held. For fixing the plate in a fixed position, other means may be provided in s © _{9 9} provided daß.diese not interfere with the processing steps and- the printed surface

do not damage it.

When the printing plate is in register as shown in FIG is attached and secured in place, it will be sheared along its width. Thanks to the register areas 18 and the fastening of the plate in position, a precise shearing of the widthwise edges in relation to the printing area is achieved 16 scored. The shearing of the broad edges can, as desired, before or after the front ends of the plate are sheared off by a shearing device 36.

The front ends of the plate are sheared, punched and bent in the manner shown in FIGS. K and 5, but in any order. When the plate 10 is in a fixed position, the shear means 38 grips the plate to accurately shear the end edges of the plate with respect to the printing areas. The punching of slots for engagement with the pressure plate carrier or pressure foundation can be done by means of a punch kO, which is also part of the shear device 38.

In order to prevent the plate from moving / out of its fixed position, the sequence of shearing off the Ends, punching and bending performed without the plate is released during the individual process steps or between them. So once the Front ends of the plate are detected for processing, the sequence of steps of shearing, punching takes place and bending, optionally with simultaneous stretching of the bent section, before releasing the plate.

In Fig. 4 and 5 grip the front ends of the metallic substrate 12 of the printing plate 10, which is attached to the vacuum

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table 30 is held in a fixed position, the shearing device 38 and the punch ^ O on. The shearing device 38 and the punch ¹ JO can be pivoted for bending in the direction of arrow 41 and can be loaded for stretching the plate during bending in the direction of arrow hZ . Optional stretching occurs in cases where metallic substrates tend to spring back to their normal flat position, that is, when spring steel is used. In such cases, the stretching during the bending helps ensure that the bent state is securely maintained. After the end of the bending process, the plate is released from the front processing devices and is now ready for attachment to a printing plate carrier or saddle.

After work s step follow the. 4 and 5, the device used to hold the plate in a fixed position, for example the vacuum table 30, is switched off, and the edges k6 of the prepared printing plate kk are now in perfect condition for attachment to the printing plate support of a printing machine by means of the slots 48 according to FIG aligned and curved.

Although the invention above is for the sake of clarity only by procedures using - ■ light-curable masses was described, it is of course also in other procedures for processing Printing plates, for example photo-engraving, thermal engraving or direct etching, applicable.

The printing plates formed by the method according to the invention can be used in a variety of printing processes, including without Restriction to this - in gravure printing, flexography

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Letterpress and dry offset processes, used with advantage will.

Patent claims

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Claims (2)

■ "β- 23Q6200 P a t e η t st η s p r ii c h e Process for preparing a printing plate for exact registration on a printing machine, characterized in that register areas are provided in the non-printing areas of a printing plate with a thin metallic layer or a thin metallic support layer with the Itß ^ i. &'tQT'b.ereißiLeii' is attached in a fixed position, the plate is sheared along its width; the plate is sheared off at the opposite ends of its length and provided with punching slots for the bridge plate carrier and the edges provided with the slots for the printing plate carrier are bent. 2. The method according to claim 1 ₁ . characterized in that _t the plate is stretched in the longitudinal direction when bending for preventing de, s spring-back of the bent edges to their original position. Blank page