US1700219A - Apparatus for offset printing - Google Patents

Description

e E 9 R W .,m 1A wwf m, MM 7, m l 5,9% TNY SAB Jan. 29, 1929.

w. GEGENHEIMER ET A1.

APPARATUS FOR OFFSET PRINTING Filed Aug. 29, 1924 Passed-Jas. 29,19i19 i UNITEUSTATES f www f WILLIAM eEGnNHnmnn, or BALDWIN, AND ERNEST E, mmm, or Pon'rv WASHINGTON, NEW Yoan. Y

APPARATUS FOR OFFSET PRINTING.

Applioationnled August 29, k1924:. Serial No. 734,966.

This invention relates to'an apparatus for indirect, three member of offset prmtmg and But this has notresulted in the most del sired results, because, as we have discovered,

E it has for its object to provide means whereby\ no means is thereby provided for adequately a plurality of films of ink, color or dye are transposed from the late to the blanket, the result being that the eposit from the blanket to the paper, fabric or other body receiving the println isvery much greater than heretofore possible in offset printing. Forexample, the usual indirect, three member, offset black printing appears gray or impoverished j when compared to work done by direct, two

member printing, because of certain reasons which are pertinent to an understanding of 'le the present invention. l

' In indirect, three cylinder, planographic, relief reproductive processes, such as lithography, metalography, offset, rotary, and also such processes using-plates etched or otherwise wrought in relief, or other kindred processes, the chemical antipathy between oil and water is customari-ly utilized, and the work, design, pattern or text from which reproductions are to be taken is laid down on, above or in below the surfaces in substances having a greater affinity for oils, fats and greasesA than for water and other chemicals possessing similar attributes, this work then being charged with lsufficient additional ink, dye or pigments in oils or binders to transfer its design from the primary to a second cylinder, customaril covered with a rubber blanket or other slightly yielding or elastic composition or-surface, which ink or color this secondary cylinder in its turn re-transfers to the third member orcylinder carrying the material on which reproductions are wanted, conducted to'contact by this third cylinder. 4

We have found that there is not, under all conditions, a sufficient affinity between the inked designs'on the primary or plate c linder and the surface of the secondary or lanket` cylinder for the latter toaccept ilms of ink in suilicient volume, at a single inking from the primary surface to enable it to, in its turn, lay sufficient of that deposit onto the sheet to be printed to give sullicient density or covering qualities to reproduce as desired.

In the effort to obtain a suficient-to-print deposit of ink, it is customary to distribute by rolling contact, re eated films of ink onto the primary surface y passing over that surface one, two, three, four or more rollers, each in its turn depositing a modicum of ink onto the primary surface.

-athy etween inks, dyes and colors and the re-depositing this ink from the primary to I the secondary surface other-than by means of 00 a single contact between the primary and the secondary.` Between these latter two, there 1s less affinity for inks, dyes or colors than there is between the patterns on the primary cylinder and the form rollers carrying,v inks thereto from their source in the ink-fountain or other means of replenishing inks, dyes or color as it is being necessarily a lied.

Obviously, there is a closer a ity between identical substances than between differing 7- ones, and, as but a single contact or revolution of inking between the primary surface and the substances, ink and rubber, customarily, it is 7.??

proposed by the present method and apparatus to secure greater affinity, not by still fur ther piling up ofink on the primary cylinder but b overcoming the usual effect of antiprubber, fabric, composition or other surface of the secondary cylinder by repeated inkings of ink on ink, chemical on the same chemical, from the Aprimary to the secondary surface. The second inking deposits a film of ink onto a film of ink, for which it has a greater aiiinity than in the first inking which .deposits a film of ink onto a rubber or other surface hostile to such reception or application.

In the indirect, three member, oiset press and process, the method is achieved by eectlngtwo or more rotations of'the plate and blanket cylinders during two rotationsof the im ression, or paper-Carr ing, or feed cyli 1n er, two functionings o 'the inking to one functioning of the printing,'one rotation of the feed cylinder being idle, it being retracted. Any suitable means canbe provided for effecting this result.- For example, the feedor impression cylinder carrying material to be printed upon-cylinder may be geared with the plate and blanket cylinders so as to be simultaneously rotated therewith, but may In the drawings we have illustrated diagrammatically a typical rotary offset press.

Figure 1 represents in diagrammatic form a sectional side elevation of said press and Figure 2 represents in plan, and somewhat diagrammatically, means for eifectlng a bodily movement of the impressioncyl1nder or feed-roller while maintaining it in mesh with the plate and blanket rollers or cylinders.

In the drawings, A represents the im ression or feedcylinder, B the blanket cylinder and C the plate cylinder, it being understood that the said cylinders are geared together to rotate at the same speed. D represents inking rollers connected by the riders E and intermediate rollers F, to the distributingi drum G for the ink. K represents the ink uct, J the usual vibrator, M the water distributor and L the damping rollers. The feeding board is indicated at P.

The impression cylinder or feed roller A is mounted in the frame of the machine in any suitable manner, for bodily movement, the projecting ends of its shaft 2 being connected to a yoke arm 4 which extends over a rotary cam-disc 5 having a cam groove 6 entered by a pin 7 on the yoke. The cam groove 6 is designed in accordance-with the number of rotations desired in the plate and blanket cylinders, relative to an effective movement of the feed cylinder. The cam groove 6 is also so designed that the bodily movement imparted to the feed cylinder A is insufflcient to Withdraw its gears from mesh with the gears of the blanket cylinder. In other words, the action of cam 5 is to periodically move feed cylinder A out of co-operative position relative to blanket cylinder B yet the feed cylinder continues its rotation, while the actual feeding in of material is suspended so far as printing contact is concerned.

During the idle or unproductive rotations of the feed cylinder, the plate and blanket cylinders are rotated to deposit two or more lms of ink upon the blanket cylinder, the more willing reception b the blanket of the plurality of lilms being ue to the affinity of ink for ink, whereasl in the old method the massing of ink upon the plate cylinder and the rotation of that cylinder but once for each printing operation of the blanket cylinder merely resulted in the transfer to the blanket cylinder of an amount of ink substantially xed by the low surface affinity for ink posessed by the blanket, which as hereinbefore stated, is inadequate. Any attempt to in crease this uantity takes the process outside the realm o printing and becomes mere mechanical smearing.

We have above described our preferred method of operation. However, it will be understood that the method may also be carried out by rotating the plate and blanket cylinders a greater number of times than the active feeding movements, that is to say, printing movements of the gripper, nnpression or feed cylinder. Thus, the plate and blanket cylinders might be rotated five times to four printing operations, and the result would be a more adequate deposit of ink upon the material receiving the latter, and yet the plate and blanket cylinders are not given, in this instance, two or more rotations to a single active rotation of the feed cylinder. The reason for the practicability of this modified method is that when the plate cylinder delivers to the blanket cylinder two or more films of ink, the blanket cylinder will not' deposit all of that ink upon the paper, but suiiicient remains to receive, by the atlinity of ink for ink, a greater quantity of ink from the next deposit from the plate cylinder than would `be the case had the plate initially deposited a single film upon the blanket cylinder followed by the impression of that blanket cylinder upon the paper, which would exhaust or substantially exhaust that deposit.

It lwill be understood that the press illustrated in the drawing, and the means for causing the relative periodic inaction between the blanketcylinder and the impression or feed cylinder are merely illustrative, inasmuch as the principle of the invention may be applied to widely different apparatus,

what we claim and desire to secure by Letters Patent being as follows,-

In an apparatus for offset printing, a plate cylinder, a blanket cylinder and an impresslon cylinder, means for rotating said cylinders and means for moving the impression cylinder out of operative position relatively to the blanket cylinder and for holding the `impression cylinder in an inoperative position whilst the plate cylinder is oEsetting a plurality of superposed films of uni-color ink upon the blanket cylinder. f

In testimony whereof, we names to this specification.

rWILLIAM GEGENHEIMER.

ERNEST E. BARNEY.

have signed our

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