US2851948A

US2851948A - Planographic dampening apparatus

Info

Publication number: US2851948A
Application number: US641318A
Authority: US
Inventors: Chester H Lucas
Original assignee: WILLIAM GEGENHEIMER CO Inc
Current assignee: WILLIAM GEGENHEIMER CO Inc
Priority date: 1957-02-20
Filing date: 1957-02-20
Publication date: 1958-09-16
Anticipated expiration: 1975-09-16

Description

.5 w? 00 RA, E 4 m c N N R w, J? 2 T ,A m 64/ c. H. LUCAS PLANOGRAPHIC DAMPENING APPARATUS Filed Feb. 20, 1957 Sept. 16, 1958 2,851,943 PLANUGRAPHTC DAR EVENING APPARATUS Chester H. Lucas, Eroolnlyn, N. Y., assign-tor to William Gegenheimer (30., Inc, Brooklyn, N. r1, a corporation of N ew York Application February 20, 1957, Serial No. 641,3l8 8 Claims. (Cl. 1ill--l48) The present invention relates to a novel and improved planographic dampening apparatus.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

Of the drawings:

Figure 1 is a fragmentary, schematic cross section through the dampening mechanism of a rotary planographic printing press;

Figure 2 is a fragmentary top plan view of a portion of the apparatus shown in Figure 1;

Figure 3 is a detailed View showing the means of the present invention for accurately and minutely controlling the amount of water remaining on the fountain roll to be fed to the dampening roll, and is a section taken on the line 3-3 of Figure 2;

Figure 4 is a sectional view taken on the line 4-4 of Figure 3; and

Figure 5 is a detailed plan view of one of the translucent, resilient wiping elements shown in Figures 1 to 4.

The present invention has for its object the provision of a novel and improved dampening apparatus for use with rotary planographic printing presses and in which means are provided for minutely and accurately controlling and varying the amount of water fed from a water fountain to the dampening roll. A further object is the provision of a novel and improved, relatively inexpensive and easily installed device for regulating and accurately controlling the amount of water fed from the feed roll of a water fountain in a planographic printing press.

In the planographic process, the proper inking of the planographic plate depends upon the repeated application to the surface of the plate of a relatively small and accurately controlled quantity of water, and difficulties of different kinds are encountered if the amount of water fed is either too much or too little. The correct amount of water should be applied as a thin film to the surface of the planographic plate so that its various areas may continue to be properly ink-receptive or ink-rejecting, thereby controlling the acceptance of the greasy printing ink by the areas of the plate and enabling the surface of the plate to reproduce the intended design.

The planographic plate is usually in the form of a thin metal sheet of zinc, aluminum or other metal which can be rendered selectively ink receptive and rejecting, and this plate, with the design formed thereon, is mounted on a rotatable printing cylinder which runs in contact with one or more dampening rolls and is subsequently contacted atent U with one or more rolls charged with a greasy ink which adheres only to those areas which were not wet by the water-charged dampening rolls, after which the inked planographic surface is pressed against an offset blanket or the sheet of paper to be printed, transferring the ink from the surface of the plate to the offset surface and thence to the paper to be printed, or directly transferring the ink to the paper to be printed.

A conventional and typical dampening system of the prior art includes one or more rolls, each covered with a water absorbent surface, such as a flannel or other cloth sleeve, which rotate in contact with the surface of the planographic plate and also in contact with the surface of a vibrating intermediate rotating roll, the surface of the intermediate roll being periodically charged with a film of water by a fabric covered ductor roll which oscillates between contact with the intermediate roll and a fountain roll, the fountain roll rotating while dipping into water contained in a fountain or trough. The period of oscillation of the ductor roll and its dwell against the fountain roll and the intermediate roll and/or the speed of the fountain roll are usually adjustable to vary the amount of water transferred, but in some conventional systems means are provided for controlling the thickness of the water film on the fountain roll. These systems are usually relatively complex, and in practice do not give complete satisfaction due to the variations encountered in running in the amount of Water transferred from the fountain to the form-dampening rolls.

The apparatus of the present invention may be applied to existing dampening mechanisms with only slight modifications, at most, or may be designed and installed originally on the planographic press. The apparatus comprises means for regulating the amount of water on the surface of a fountain roll by creating and by regulating the width of narrow moistened bands of water on the fountain roller which are available to be transferred to the ductor roll and to the intermediate vibrating roll, the bands of water-film remaining on the fountain roll being of a thickness determined by the thickness of the water film which is normally retained on the fountain roll, and means are provided whereby the width of each of these narrow bands may be varied at will so that different width-wise portions of the plate may each receive an accurately and minutely variable quantity of water in accordance with its requirements. The fountain roll works with an oscillating ductor roll which transfers the water film bands to a vibrating intermediate drum, and this in turn transfers the Water to the fabric or papercovered moistening rolls which run in contact with the surface of the planographic plate and keep it properly moist.

The width of the narrow bands of water film remaining on the fountain roll are individually controlled by means of a plurality of adjacent, and preferably contiguous leaf spring members which are individually pivotally mounted on a shaft parallel to the fountain roll and may be selectively brought into light or heavier contact with the surface of the fountain roll to remove substantially all of the water from the fountain roll, as it rotates, at the narrow areas of contact of these leaf spring members with the fountain roll surface. The forward ends of the leaf springs are each pointed, and they are so positioned that each of them may be selectively raised out of contact with the surface of the fountain roll, or may be pivoted into contact with the surface of the fountain roll, each leaf spring first touching the roll only at its point, and engaging a progressively wider line portion of the roll surface as the leaf springs are further deflected, the point of line of engagement of the leaf springs with the roll forming a wiping member to remove Water from the surface of the roll and leave a more or less wide narrow band on the surface of the roll between adjacent springs, as the roll rotates. Each of the leaf spring members is frictionally held in the position to which it is moved, and the leaf springs are preferably close enough together so that when they are fully depressed, substantially no water remains on the surface of the roll between adjacent leaf members. The leaf spring members may be made of various resilient materials, but a transparent or translucent plastic material is preferred so that the line of contact of each leaf spring wiping member with the fountain roll surface may be seen, especially when the line of contact is wet, as it is during operation of the planographic press.

It will be understood that the foregoing general description and the following detailed description as well are exemplary and explanatory of the invention but are not restrictive thereof.

Referring now in detail to the present preferred and illustrative embodiment of the present invention as shown by the accompanying drawings, there is provided a rotary printing cylinder having a planographic printing plate mounted thereon. The correct amount of water for the planographic process is applied to the surface of the planographic plate on cylinder 10 by means of the dampening rolls 12 which roll in contact therewith and transfer a regulated amount of water to the surface of the planographic plate. Rolls 12 are supplied with moisture from the vibrating intermediate roller 14 which is replenished by periodic contact with the ductor roll 16, mounted for periodic oscillation in the arms 18, and in turn, is replenished by contact with the moist surface of the fountain roller which receives water by dipping into the water maintained in the fountain 22.

The surfaces of all of the

rolls

12, 14, 16 and 20 are all water-receptive to provide a consistent and reliable transfer of water from the fountain 22 to the printing surface on cylinder 10. Preferably, and usually, the rolls 12 and the roll 16 are covered with a flannel or other cloth sleeve, as is usual, while the

rollers

14 and 20 are preferably formed of stainless steel, or other noncorrosive, water-receptive material and in any event are provided with water-receptive surfaces which allow the formation of a substantially uniform film of water on the surface of the rollers.

Cylinder 10 is driven from the press mechanism, and fountain roll 20 maybe driven continuously or periodically, so long as its surface is continually provided with a film of water or other moistening liquid. Roll 14 is gear driven and rolls 12 and 16 are normally rotationally and frictionally driven by their contact with other driven members. Ductor roll 16 is oscillated at a relatively fast frequency so that it contacts rolls 14 and 20 alternately every few seconds, and preferably has a period of dwell in contact with one or the other of these rolls for a short period of time such as a fraction of a second up to one or two seconds. Some of the rolls of the dampening apparatus are preferably vibrated, that is, moved axially from end to end, and most conveniently the intermediate roll 14 is so moved, thereby distributing the moisture on its surface over a width which may be approximately equal to one or two widths of the bans of moisture on its surface.

For regulating the amount of moisture or water left on the surface of the roll 20 prior to its contact with the ductor roll 16, and thereby minutely regulating and accurately controlling the quantity of water available for application to any lateral area of the planographic printing member on the cylinder 10, means are provided for wiping the surface of the roll 20 in narrow bands of variable width. As embodied, a parallel shaft 24 is mounted to one side of the roll 20 and is supported in brackets 26 which are removably supported on the rear wall 28 of the fountain 22, shaft 24extending from one end to the other of the roll 20.

On shaft 24 are mounted a plurality of adjacent and substantially contiguous leaf spring members 30 adapted to engage the surface of the fountain roll 20 and which may be individually and selectively further deflected to bring a widening portion of the leaf spring member 30 into wiping contact with the surface of the roll 20 to remove a variable width of the water film on the surface of the roll 20 from the surface, thereby preventing its transfer to the ductor roll 16 and returning the removed water to the fountain 22. The leaf spring members 30 may also be raised to a position where they are out of contact with the surface of the roll 20 so that the maximum amount of Water is transferred from the fountain to the plate on cylinder 10.

The leaf spring members 30 are preferably formed of a relatively stiff, but flexible and springy, transparent or translucent plastic sheet material, such as Vinylite, cellulose acetate or methyl methacrylate, and are conveniently from about 0.010 to 0.025 thick. Each of the members 30 is preferably formed with a relatively sharp point 32 and is of such a length and position that the point 32 of each of the members 30 may be engaged with the surface of the roll 20, or by flexing the member 30, wider portion of the member may be engaged in contact with the surface of the roll 20, as shown in Figmres 1, 2 and 3, the lines of contact being shown in Figure 2 by the dot-dash lines 34. Preferably, the underside of the members 30, when they are made of transparent material, is roughened, and the line of contact 34 shows as a line due to the transparency imparted to the roughened surface of the material by the water lying between the member 30 and the surface of the roller 20.

The leaf spring members 30 are mounted for individual pivotal movement about the shaft 24 by means of frictional brackets which can be manually adjusted. As embodied, each of these brackets comprises a U-shaped portion 36 preferably snugly fitting the shaft 24, one leg 38 being turned over, as at 40 to overlie the other leg of the U. Each bracket 36 is provided with short headed stud 44 having its head bearing against the shaft 24 and is spring pressed against the shaft by means of a compression spring 46 encircling the stud 44 and compressed between the head of stud 44 and the inner surface of the turned over portion 40. The outer end of the stud 44 serves as a lever or handle, by which the bracket 36 and its associated leaf spring member 30 may be pivotally moved about the shaft 24.

Leaf spring members 30 are removably held in their individual brackets 36 by means of a plate 48 which is positioned between the outer end of the compression spring 46 and the inner face of the turned over portion 40, the forward edge of the plate 48 being bent to provide an entrance gap for easy insertion of the slotted end 50 of the leaf spring member 30, the member 30 being frictionally held in the position shown by engagement between the plate 48 and the turned-over portion 40.

The leaf spring members 30 are shown in several positions of adjustment in Figure 2 where the uppermost member 30 is out of contact with the roll 20, the next is in engagement only at its point, the next engages along a short line to remove water from a narrow band on the surfaceof the roll 20-while the next two members 30 are in full engagement with the surface of the roll 20 thereby shutting off completely the supply of water from the fountain to the surface of the printing plate on cylinder 10 in certain areas.

Due to the translucent or transparent nature of the material from which the leaf spring members 30 are formed, the press operator can easily judge by visual inspection the relative'width of the wiped portion of the fountain roll 20 and thereby minutely and accurately control and'regulate the amount of water supplied to the various widthwise portions of the roll 20 and the printing plate on cylinder 10, varying and adjusting the flow of water as required by the printing being produced during the operation of the press.

The invention in its broader aspects is not limited to the specific mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages,

What is claimed is:

1. Ina dampening mechanism for a planographic printing press, the combination of a rotatable water-fountain roll to supply water to the printing surface, and a plurality of leaf spring, flexible wiping members adjacent to each other and having pointed tapered ends to engage the surface of the roll to remove water therefrom, and means for individually and selectively varying the engagement of the leaf spring members with the surface of the roll to vary the width of the roll area from which water is removed.

2. Dampening mechanism as claimed in claim 1 in which, the leaf spring wiping members are pivotally mounted adjacent to the roll and may be moved and frictionally held in their various wiping positions.

3. Dampening mechanism as claimed in claim 1 in which the leaf spring members are sharply pointed and are pivotally mounted and individually movable on a shaft parallel with the roll whereby they may be moved into wiping contact with the roll along various widths-of the roll.

4. Dampening mechanism as claimed in claim 1 in which the leaf spring wiping members are formed from relatively stiff, resilient, plastic material which is at least translucent whereby the line of contact between the several wiping members and the roll is visible to the operator.

5. A mounting for a leaf-spring like wiping member to engage a fountain roll in a planographic printing press comprising a shaft, a U-shaped member mounted thereon and having a turned over end on one leg, a plate underlying the turned over end, a headed stud passing through the turned over end and the plate, a spring compressed between the head of the stud and the plate to force the stud head against the shaft and the plate against the turned ever end, and a roll wiping member in the form of a leaf spring frictionally held between the plate and the turned over end.

6. In a planographic printing press having a fountainfed roll to supply water to the dampening rolls, the combination of a plurality of contiguous, side-by-side wiping members engageable with the surface of the fountain-fed roll, each of said wiping members being in the form of a leaf spring member having a pointed end of varying width at that portion which is engageable with the surface of the roll, and means for selectively and individually, variably positioning the members so that a variable width of the members is engaged with the surface of the roll to remove water from varying widths of the roll.

7. A structure as claimed in claim 6 in which the several leaf spring members are pivotally mounted adjacent the fountain-fed roll and are movable to and frictionally held in various positions relative to the roll, with their leaf spring members variably engaging the surface of the roll.

8. A structure as claimed in claim 7 in which the leaf spring members are formed of transparent sheet plastic material having the side adjacent the roll roughened to render the plastic translucent but transparent when wet with water between the member and the roll.

References Cited in the file of this patent UNITED STATES PATENTS 1,364,257 Dobbertin Jan. 4, 1921 2,669,927 Ellis Feb. 23, 1954 v FOREIGN PATENTS 400,278 Great Britain Oct. 23, 1933 804,933 Germany May 4, 1951