US1574163A - Method and apparatus for the production of prints - Google Patents

Description

Feb. 23 ,1926. 1,574,163

A. C. OHEIM ET AL METHOD ANDAPPARATUS FOR THE. PRODUCTION OF PRINTS Filed August 16, 1923 JBZ S. l

Patented Feb; 23, 1926.

-- UNITED STATES" PATENT OFFICE.

MANY, ASSIGNORS TO THE FIRM EMIL GERASOH G. M. 1B. 11., OF LEIPZIG, GERMANY.

METHOD APPARATUS FOR THE PRODUCTION OF PRINTSi -App1lcatio1i filed August 16, 1923. Serial No. 657,778.

Method and Apparatus for the Production.

of Prints, of which the following is a specification.

It has alreadybeen proposed, when making proof impressions, so-called pulls, to

use the ordinary lithographic hand-press for obtaining offsets. This, however, entails a structural modification of the press to the extent that a hinged frame, in which the elastic cloth is stretched, must be provided and that the scraper of the press must be replaced by a special roller. It has also been proposed to use for the same purpose a divided frame, in the lower part of which theform is clamped, while the rubber cloth is clamped, to two sides in a hinged frame,

a third frame being provided between the other two frames, in which the paper to be printed is stretched. In this case as well the ressure of a roller is employed, when the ithographic hand-press is used- In both the above mentioned cases the transfer of the impression to. the rubber cloth is effected by the latter being laid on the form, that is by direct contact of the cloth with the printing surface, which, apart from the fact that the cloth is stretched only to two sides, which always causes the two other edges of the cloth to curve inwards more or less, is one of the principal causes of bad work and socalled smudging and doubling.

the method of producing prints of all kinds,

- whereby in an ordinary lithographic handpress without any structural modifications of the same, that is, by using the scraper of the press and a double frame, which is adaptedto rest on the carriage of the hand press and to contain, the form and the stretched rubber cloth, to produce prints from all forms in low and high relief and of letter press forms, both directly and indirectly, and hence also for pulls suitable for offsets. It has hitherto not been possible to carry out all such work in cylinder or platen presses.

The invention consists substantially in a particularly advantageous way of utilizing the vertically acting pressure of the scraper of the litho aphic hand-press, by the rub- ALFRED CARL OHEIM, ALFRED SYHRE, AND OTTO HENTSCHEL, OF LEIPZIG, GER

ber cloth, w ich is stretched tightly in the upper hinged art of the double frame, does not touch the orm, when the frame is closed and is provided in the usual manner with a protective covering, said cloth being brought against the printing surface by means of the vertically acting scraper and the impression being thus produced. I

The peculiarity of this method consists in this, that, owing to the small distance of the rubber cloth. from the form and to its being uniformly and tightly stretched, which prevents it from being pulled in at the sides, the pressure of the scraper always causes the contact between the rubber cloth and the form to take place in a progressive, straight line, as the ,elastic cloth always keeps its distance from the form immediately in which is effected by the said cloth' being.

firmly fixed at two opposite edges of the hinged frame and held at the two other sides of the frame by easily displaceable clamping devices, which, on the rubber cloth being stretched and the front movable limb of the frame being adjusted for this purpose, are adapted to give until the required tension in the rubber cloth is obtained, in which position it is then secured by fixing the clam ing devices, provides the possibility of ma ing indirect prints of all kinds, even from flat forms and on the roughest paper or the like, as the requisite pressure is obtained from the powerful action of the pressure of the scraper and the counter-action of the tension of the cloth. A further advantage of the present method and ofthe apparatus for carrying out the same consists in this, that it may be used for copying directly on to zinc plates, such as are used for making offsets. It should be specially mentioned other negative, this foil being laid between that the foil used as a negative for this purpose can be printed on indirectly and directly at the same time and that by this accurately superposed printing on both sides the impressions are caused to register particularly well.

The foil used in place of a glass negative, for instance a thin gelatine sheet, tracing or transparent paper and the like, may be .printed on directly and indirectly, in other words. on both sides at the same time in one operation, in the following manner After the form, which is held in the double frame, has been inked, an impression of it is made on the rubber cloth. The form is thereupon inked again and an impression made on the sheet of gelatine placed between the form and the rubber cloth. The print thus obtained, on which the front and back impressions are in perfectly sharp register, ensures in the first place a sufficiently good register for copying purposes and consequently an equally sharp copy, irrespective of whether it is illuminated for obtaining a direct or an indirect print. Inv every case a colour covering layer will be caused to lie on the copying layer.

According to previous processes for the production of negatives it was impossible-to obtain a sharp print, as the printed side could not be placed on the copying sheet, and thus lack of sharpness resulted, varying according to the thickness of the sheet. According to the invention this is prevented in that the negative transferred on a rubber cloth is transferred on a thin sheet of foil in one operation with the production of antheprinting stone (lithograph) and the rubber cloth and the latter pressed against the foil while, if required, another sheet lying under the foil oralso the same sheet may be printed on both sides. There is thus obtained a foil by means of which negative as well as positive copies may be made, as the printed surface lies directly on the copy to be made.

Thus, for instance, it is possible to obtain negative foils from engravings, by inking the surface of the engraved form with the roller and conversely to obtain negative foils from etchings, b inking with the tympani As the method of offset printing has such a number of applications, the use p of the foils may also be very varied.

A constructional example of the apparatus for carrying out the method is shown in the drawing Fig. 1 shows the apparatus open and without therubber cloth in perspective.

Fig. 2 is a side elevation with the rubbe cloth in position, looking in the direction opposite to the arrow B in Fig. 1,

Fig. 3 is a plan view looking in the direc tion C of Fig. 1, I

Fig: 4.- is a cross-section through the closed form, during the taking of an impression,

Fig. 5 is a view from above of a clamping bar for the rubber cloth,

Fig. 6 is a cross-section through one of the side members of the frame on line A'A of Fig. 1Twith the rubber cloth in position.

Fig. 7 is a fragmentary perspective view of one of the side members of the frame is laid on the carriage of the lithographic hand-press, the frame being provided with clamping screws d for this purpose. Adjusting screws 1) are fitted in the frame a and project below the bottom surface of the latter. These screws are adapted to rest upon a table or other support on which. the form 1 is disposed and thus by uniformly adjusting the several screws b the frame a be raised or lowered so as to bring the latter into proper position with respect to the printing form 1. Subsequent to this adjustment of the frame a, the form 1 is secured inposition therein by tightening. the clamping screws d. A frame it, in which the rubber cloth 2 is tightly stretched, is attached by hinges k to the frame a. The rubber cloth is fixed to the side member h of the frame h lying next the -hinge by a clamping bar 7 and to the front adjustable side member h by means of a similar clamping bar e, while it is at first not rigidly fixed to the two side members 72. and hof the frame 71, but attached, so as to be capable of giving. This is effected by the rubber cloth 2 being held in the side members h and h by clamping devices g and slotted clamping bars m, which are adapted to slide easily in guiding grooves c of the side members it and h of the frame, until, by adjusting the tensioningmember h, the rubber cloth has been given the required uniform tension in all. directions, in which position the clamping devices 9 are fixed by tightening the screws, which pass through the slots in the clamp bar m, the rubber cloth being thus secured'in its stretched state. By lateral guide plates Z on the hinged frame h, which are adapted to engage the sides of the frame a, the relative adjustment of the two frames is secured, so that there be no lateral relative movement.

For operating the apparatus the frame it is hinged over on to the form 1, care bein taken that the rubber cloth 2 shall not toucl f the printing surface of the form 1, but shall maintain a small distance a: from it (Fig. 4). On the rubber cloth, which forms a perfectly even, tightly stretched surface, being brought in contact with the form 1 by the vertical premure of the scraper 3, the cloth is pressed down at an inclined angle in such a manner that it can only come in contact with the surface of the form along a straight line, which travels from one side of the form to the other. The sharp and hard application of pressure by the scraper is eased and caused to be uniform by the oppositely acting tensional force of the rubber cloth, which makes the pressure of the scraper adaptable to the surface in a way which is impossible by any other printing process, the present method thus having all the advantages obtainable with the offset cylinder machine.

1n the present method. however, it is unnecessary to 'make ready specially, as no rigid support is used and an adaptability to the form is obtained, such as is impossible even when using a cylinder in fixed bearings.

\Vhat we claim is E 1. A method of producing prints in an ordinary lithographic hand-press, consisting in tightly stretching the rubber cloth evenly in all directions in the part of the frame adapted to hold it, bringing the stretched cloth over but not into contact with the form, thereupon pressing the cloth into contact with the form by means of the Vertical pressure of a scraper along the edge of the scraper and running the carriage with the frame through the press under the scraper, as and for the purpose-set forth.

2. A method of producing prints in an ordinary lithographic hand-press, consisting in tightly stretching the rubber cloth evenly in all directions in the part of the frame adapted to hold it, bringing the stretched cloth over but not into contact with the form, pressing the cloth into cont-act with the form by means of the vertical pressure of a scraper along the edge of the scraper thereby transferring a colored impression from the. form to the rubber cloth, inserting a thin foil between the form and the cloth, and thereupon making an impression on both sides of thefoil in one operation of the press.

3. An apparatus for producing prints in an ordinary lithgraphic hand-press, comprising a four-sided frame capable of bolding the printing form and adapted to rest on the carriage of the press, a rubber cloth, an adjustable frame hinged to the said frame and comprising four side members, the member opposite the hinged member being adjustable, means for attaching the rubber cloth to. the hinged and adjustable side members of the hinged frame, an adjustable clamping device for attaching the cloth to the two other side members of the adjustable frame, 'said clamping devices being freely movable with the rubber cloth incident to stretching thereof by the adjustable member of the adjustable frame and also being capable of being fixed in an adjusted position.

In testimony whereof we aflix our signatures.

ALFRED CARL OHEIM. ALFRED SYHRE. IOTTOHENTSCHEL.

Images