US1335025A - Moistening device for printing-presses - Google Patents

Description

W. B. PITKIN.

MOISTENING DEVICE FOR PRINTING PRESSES. APPUCATION FILED DEC. 17, 1917.

1,335,025. Patented Mar. 30,1920.

l 20 g: E i j I i I avwe WALTER B. PITKIN', OF NEVT YORK, N. Y., ASSIG-NOR TU IPLANOGRAPHIG EQliJ'IPMENl. GUMPANY, INCORPORATED, OF NEW YORK, N. Y., A. CORPORATION OF NEW YUR'K.

MOISTENING DEVICE FOR PRINTJENEt-PRESSJEQ.

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Specification of Letters Patent.

Patented ltllar; 8d, l dtl.

2 '0 aZZ whom it may concern:

Be it known that l, WALTER lB. PITKIN, a citizen of the United States, and a resident of the city, county, and dtate of New York, have invented an improvement in Moistening Devices for Printing-Presses, of which the following is a specification.

My present invention relates to apparatus of the general type shown and described in my co-pending application, Serial No. 207,448, filed on the same date as this, in which a printing surface, such as a planographic or lithographic or other plate, is moistened by the application of steam applied through a series of jets, which case l[ have designated as (Jase A; and also my other parallel pending application, Serial No. 207,451, filed on the same date as this application, which ll call Case C.

lin general, the two applications referred to contemplate respectively the use of steam derived from an outside source, and the use of a tank of water which is brought to boiling point, by preference by an inside heating apparatus; as I have explained in one of these cases, I consider vapor of any suitable liquid as within the scope of those applications, as I do of this. The present case, which I call Case B, however,'embraces features of novelty not shown in those in that it provides means operating without physical contact for sealing the moistening tank, which is placed adjacent to the impression cylinder of the press; that is, without physical contact between the plate on the rotating cylinder (or other impression device) and the sealing means. The plate which I have especially in mind (although my invention applies to any form of printing device in which the paper, or type face of whatever kind may be selected, may be dampened in order to get a good impression) is a zinc or aluminum plate or process cut, and espe cially the type of plate now known in the trade as planographic. In these, as is generally known, an ink receiving design is formed by the use of certain classes of as phaltic compound which are 'suliiciently rigid to maintain all of the points and lines necessary for the design and to transfer the ink properly tothe paper, but which do not resist abrasion from any form of sliding contact wlthout impairlng the printing quality.

rying the plate-moistening means adjacent thereto, and sealing means for the closure between the printing cylinder and the moistening means, operating to maintain a substantially complete seal without physical contact between the plate and the sealing means; and at the same time a means is provided for producing a rapid condensation and cooling upon the printing surface and for the removal of globules and surface water, through the application of air seals to the closure between the moistening device and the tank. Une of the means which have illustrated is a series of air-jets disposed adjacent to the closure, the air being directed against the opening at a pressure sufficient to counter-balance any pressure which may be generated within the moistening tank. Other means consists of forming the edge of the moistening tank insuch a way as to make an air dash-pot effect, preferably by forming a series of square shouldered longitudinal grooves in the abutting edge or surface of the tank Where itadjoins the cylinder. It is of course contemplated that this closure shall be made as narrow as possible so that the plate may pass the same with the least possible margin. The accompanying drawings show,

In Figure 1 a sectional view, partly diagrammatic, of my improved moistenin-g.

device, I I Fig. 2 a plan of the parts shown in Fig. 1. Fig. 3 a detail of a method of forming the closure of the tank with a pneumatic dash-.

pot.

Fig. 3 an alternative form of the latter.

It will be understood that my invention is applicable to various forms of printing presses and that it is not necessarily limited to a press carrying the forms upon a cylinder, although I-have illustrated my invention in connection with an off-setpress; and it will also be understood that the specific form of my invention illustrated in the drawings and described herein may be greatly varied, without departing from its essential principles or the spirit of my invention, the drawings being illustrative merely of an operative form of my device and indicating one of the many ways 1n which it may be applied.

Referring to Figs. 1 and 2 of the drawings, 1 indicates a form cylinder, that is, the cylinder which carries printing surfaces, whatever their nature, such as planegraphic plates, etc., and which is inked by i the curvature of the cylinder 1, at one of its sides. The housing 7 is provided with means for introducing steam into theinterior thereof, which means may be the jets 8 supplied by the stea pipe 9. The steam pipe 9 is provided with a suitable steam cutoff and regulating apparatus, such as the globe valve 10. The steam jets 8 are mounted radially to the form cylinder 1 and are thus directed toward the face of the plate I upon the cylinder 1. They may be adjusted towardand away from the plate by any suitable adjusting apparatus such, for instance, as the yoke 11, which is turned upward at each end and extends across the width of the housing. The steam pipe 9 is attached to the upturned ends of the yoke and the ends of the yoke are prolonged so as to cover the --slots 12, within which the steam pipes move. Thumb screws 13 are provided for moving the yoke. They are held against longitudinal movement in the yoke 11 and are in threaded engagement with the boss 14 mounted upon the housing 7. By means of jets 8, steam may be directed against the plates of the cylinder 1 at a velocity and under a pressure suflicient to cause it to penetrate the minutest depressions in the plate 1 and to thus effectively moisten it.

Owing to the relatively large mass of the cylinder 1, condensation of the steam to some extent takes place, thus covering the v plate with water. Mounted upon the housing 7 are the air jets 15, preferably arranged to discharge upon the surface of the plate as it leaves the housing 7, due to the rotation of the cylinder 1, and pointed in a direction substantially tangential to the cylinder 1.

- The jets 15 preferably dischar e, as shown in Fig. 1, into the'opening Tietween the upper edge of the housing 7 and the cylinder 1. The discharge of air thus causes a rapid condensation of the steam upon the plate, by rapidly conducting the heat away from the plate and performs a number of other functions, among which are, preventing the steam from escaping from the housing 7, by driving it back into the housing,

. cooling the plate, removing any globules or air bubbles which may be adhering to the plate, distributing the water of condensation over the snrface of the plate, removing any surplus water of condensation and causing the water to flow over the plate, thus effectively covering any portions of the surface, -to which water has not adhered. The jets 15 may be of any suitable size and shape, and are preferably arranged at intervals across the entire width of the plate.

They may be directed at any suitable angle or at varying angles" with respect to the longitudinal axis of the plate or direction of rotation of the cylinder, and are supplied with compressed air at suitable pressure, throughthe pipe 16, which is supplied with a regulating valve 17 and is connected with any suitable source of air pressure.

The pipe 16, carrying the jets 15, may be adjusted toward and away from the cylinder 1 and housing 7 by any suitable means, such as the adjusting screw 18, which is in threaded engagement with the arm 19, carrying the pipe 16. Arm 19 is hingedly mounted, as at 20, upon the housing 7.

Located below the housing 7 is a trap 21, which is adapted to catch any surplus water of condensation.

The operation of my improved device is as follows: Steam is fed to the apparatus through the steam pipe 9, discharging through the jets 8 upon the plate and filling the interior of housing 7 with the steam, at substantially atmospheric pressure. The rotation of'the cylinder 1 carries the plate, which has been subjected to the action of the steam, into the zone of action of the air ets 15, which causes a rapid condensation and a spreading of the water over the plate, WlllCll has been described above. Any surplus water will run down into the housing 7 or trap 21, from which it may be drawn.

In Figs. 3 and 3, I show a means of makng the seal between the tank 7 and the cylinderl by means of a pneumatic dash-pot. It 1s obvious that the forms of closure here shown may be employed in connection with the airets 15, if desired; or under suitable conditions they may be employed alone. a It 1s further obvious that this form of construction may be used with the devices shown in my parallel pending applications alreadv referred to in this case, and I do not by the clalms made mean to exclude such modifications. In the figures now referred to, 7

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panacea rectangular groove 22; these are by preference interrupted at intervals by partitions 22 This lip may be conveniently formed of a single casting and only the portion of it adjacent to the cylinder needs to be finished, the finished surface being concentric With the impression cylinder, and as close to the plate as possible. The effect oi the grooves is to cause eddies due to the motion of the air or steam under the pressure in the tank, and also from the centrifugal force imparted to it by the rotation of the cylinder, the steam or vapor being entrapped in the slight recesses in the design on the plate, escaping into the grooves 92%, and there setting up eddies which create a back pressure, as is understood. l lo similar device is needed in connection with the closure upon the other side out the tank, though it might be used if desired; because the motion or the cylinder is inward toward the tank and centrifugal t'oroe will ordinarily suffice to pr vent the exit of steam or vapor, in conjunction with the trough 21 already referred to.

In Fig. 3 I have shown another shape for the grooves of the pneumatic seal. In these the lower or entering wall 23 of the groove is formed at a-slight angle, so that steam or vapor may more conveniently enter the groove where it will set up a rotary move ment creating a back pressure against the wall 24. @t course other forms of grooves may be used and the invention may, in this respect as in others, take many forms.

What I claim is:

1. A moistening device for printing presses comprising, in combination with a printing plate, means for first subjecting the plate to steam and then subjecting it to an air blast.

2. A moistening device for printing presses comprising, in combination with a printing plate, means for first subjecting the plate to steam throughout substantially its entire Width and then to a plurality of blasts of air, at intervals, throughout substantially its entire width.

3. In a device oi? the hind described, a ro-v tat-able form cylinder, a printing plate mounted thereon, a housing in close pro imity thereto, means for introducing steam into the housing, and means for subjecting the plate to a blast of air as it' leaves the housing, during the rotation of the cylinder.

t. In a device of the kind described, a rotata'ble form cylinder, a printing plate carried thereby, a stationary housing mclosing a portion of the surface of the cylinder,

means for introducing steam into the housand means for sub ecting the plate to a blast or air at a plurality of points as it leaves the housing, during the rotation of the cylinder.

5. In a device of the kind described, a rotatable torm cylinder, a printing plate tit carried thereby, a stationary housing inclosing a portion of the surface of the cylinder, a plurality of steam jets located within the housing and discharging. toward the plate, and a plurality of air jets discharging adjacent thereto.

"6.. In a device of the kind described, a rotatable form cylinder, a printingplate carried thereby, a stationary housinginclosing a portion of the surface of the cylinder, a plurality of steam jets located wit in the housing, adapted to discharge steam in the direction of the plate and adjustable toward and away from the plate, and a plu rality or air jets located outside of the houstoward the plate, outside of the housing and r ing, adapted to discharge air toward ,the

- jets ofsteam toward the plate, in a direction substantially radially to the cylinder, and means for directing a plurality of jets of air toward the plate substantially tangen-- tially to the cylinder.

9'. In a device of the kind described, a form cylinder, a printing plate mounted thereon, a housingiin close proximity to the plate, means within the housing, for direct-- ing a plurality of jets of steam toward the printing surface of the plate, in a direction substantially radially to the cylinder, and means, external tothe housing, for directing a plurality of jets of air toward the print ing surface of the plate, in a direction substatially tangentially to the cylinder.

10. In a device of the kind described, a

lllti lltl rotatable form of cylindena printing plate mounted thereon, a housing in close prorimity thereto, the housing containing steam or vapor, and means for closing the open ing between the housing and the cylinder without physical contact between them.

11.. In a device of the kind described, a rotatable cylinder and a printing plate mounted thereon, a housing in proximity to the cylinder containing steam or vapor under pressure, means for creating a back pressure between the cylinder and the edge of the housing necessary to prevent the escape of the steam or vapor.

12. In a device of the kind described, a rotatable cylinder having a printing surface carried thereby, a housing adjacent to the cylinder and containing steam or vapor, and

a pneumatic seal maintaining the closure presses comprising, in combination with a between the housing and the printing surprinting plate, means for dampening the face. plate, and means for removing surplus water l3.'In a device of the kind described, ,a therefrom, comprising means for subjecting 5 5 rotatable cylinder havinga printing surface the plate directly to the separate and succarried thereby, a housing adjacent to the cessive action of steam and of an air blast. cylinder and containing vapor or steam, and In testimony whereof, I have signed my a pneumatic seal maintaining the closure bename to this specification this first day of tween the cylinder and the exit wall of the December, 1917. 10 housing.

14. A -moisteningdevice for printing I WALTER B. PITKIN.

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