DE685533C - Method and device for producing printing forms by injection molding or spraying - Google Patents

Description

Method and device for producing printing forms by injection molding or spraying For a limited area of printing forming, the use of plastic art masses have been proposed. Such printing forms should thereby are generated that of original printing forms, z. B. from single letters or lines existing sentence forms or wayside shrines, matrices removed in some way are heated, this with the plastic mass in an embossing press and a fairly are subjected to high pressure. The product is a printing plate that is a second piece the respective original printing form. This type of approach presupposes existence of original printing forms and therefore only results in duplicates (impression clichés).

To the plastic masses used according to the generated for the To be able to dose the required amount of printing form, they should primarily be more than or less thick panels can be used, and the plastic ones are also used Masses as powders, tablets, or strips have been suggested. For each particular one In any case, the source material must always be in a certain facility State forms are procured. It is also particularly disadvantageous that the softening of the material for the printing forms takes place under the press, so that this required time the manufacturing process of the printing forms is considerably extended.

Such duplicates of original printing forms should be after another Suggestion by pouring out a material made in some way with. acid hardening Phenol-formaldehyde condensation products are produced, which, however, turn out to be proves practically impracticable.

According to the invention, printing forms are made by injection molding or spraying made of heat-softening, optionally curable synthetic materials.

In this context, printing forms are also understood to mean those of which could be printed per se, but as intermediate forms for the production of z. B. Matern can be used for printing plates.

The materials used here are relatively hard and more or less elastic synthetic masses used during their processing completely or are only in a malleable, soft state in a certain work phase, for example phenolic, carbamide, acetyl cellulose, rubber-based built-up or similar masses: after the method of the invention In contrast to the suggestions mentioned above, letters can also be used and ZeilLU i, which from time immemorial as well as = -most printing plates from Letter metal a) e-. and are mainly manufactured by injection molding. In terms of quantity, they make up the vast majority of all printing forms used represent.

An advantage of the method of the invention is inter alia. in that at Manufacture of the printing molds by injection molding the mold cavities closed on all sides so that the most accurate mapping is achieved without any burr, entirely in the Contrast - for example, "to the pressing process, where the open form after filling with the mass is closed, so that a burr always arises in the parting line of the mold and also the dimensions of the body produced by pressing according to the inevitable fluctuations in dosage are different to the extent that is by no means permitted in the case of printing forms. Another advantage is that both in injection molding and in spraying with a sufficient level in practical operation Speed can be worked in contrast to your pressing process and casting process.

In a manner known per se, one becomes the negative for the method the form containing the printing form to be produced is used, with, as also on known, e.g. B. by shut-off devices between the separately arranged melting chamber and the shape of the feed of the plastic masses is controlled.

With regard to the fact that printing forms are often worthless after their use reusable (regenerable) plastic ones are particularly advantageous Masses used, d. left those that do not undergo any chemical change when they solidify suffer and which are converted back into a malleable state by mere heating can be.

The plastic masses are in a special melting container brought out of the mold to the state suitable for the manufacturing process and kept in this state, e.g. B. by heating and, if necessary, temperature control.

Since most of the plastic masses their movement is proportionate oppose great resistance, the movement is generated in a known manner accelerated a pressure difference, z. B. by the outer container wholly or partially- exposed to the pressure of a gas or a liquid or a solid 'displacer will.

The material can be fed into the outer space in any form be so that z. B. used printing forms without any pretreatment, such as pulverization or the like 'again': brought into the cycle and processed into repentant farms can be.

'-' The method according to the invention enables fast work, because you have the shape and the melting space for the injection molding or injection molding compound in different can keep practically constant heat, for example by changing the shape cooled to the temperature necessary to solidify the masses, the outer container on the other hand, the heat required to soften the masses is supplied.

Parts of the printing form produced by the method according to the invention can also consist of other material, for example from foreign metal etchings Origin. It is a major advantage of the invention that such parts are injection molded as well as in the case of spraying already such a firm connection with the rest of the plastic Masses existing form enter that. special fastening measures, for example No need for nails, putties, etc. It has already been suggested to use metal etchings to be poured into printing forms made of lead alloys. However, since the etchings that mostly made of copper or zinc, have a lower specific weight than the lead alloys, it is necessary to use special measures, e.g. B. Feathers or metal blocks worked exactly at the height, in their position in the form to secure. This is unnecessary in the production of the printing formes according to the invention, because the spray material has a very low specific weight. Through this In an advantageous embodiment of the invention, the production of the printing forms is essential accelerated and at the same time the accuracy of the Forin significantly improved.

For shapes that are relatively stretched in one or more directions are, according to a further embodiment of the invention, the outer container, in which the plastic masses are initially located, several supplying the form Outlet openings, or several outer containers are provided. It can also the outlet opening over the correspondingly designed shape or this under the Outlet opening are moved away. This ensures that the filling is even favored by the shape.

The manufacturing process according to the invention is similar to that of the known one Equipment for injection molding or spraying of metals, with of course corresponding your plastic material used to train these facilities in a special way are.

Claims (1)

PATENT CLAIMS: i. Process for the production of printing forms by Injection molding or spraying, characterized by the use of heat softening, optionally curable plastics. z. Method according to claim r, characterized in that in the injection molding or spraying parts paus, others Material with: the plastics are combined. 3. Device for executing the Method according to claim i, characterized in that the outside of the mold Melting vessel has several outlet openings supplying the F ,, crm, or several such containers are provided, or that the outlet opening of the container can be moved over the mold or the mold under this outlet opening.