US2913980A - Lithographic dampening mechanism and method - Google Patents

Description

Nov. 24,. 1959 R. E. LINDEMANN 2,913,930

LITHOGRAPHIC DAMPENING MECHANISM AND METHOD Filed Nov. 27, 1957 3 Sheets-Sheet 1 SUPPLY TA K INVENTOR. ROBERT E.LINDEMANN u/M M1 7" Nov. 24, 1959 R. E. LINDEMANN 2,913,980

LITHOGRAPHIC DAMPENING MECHANISM AND METHOD Filed Nov. 27, 1957 s Sheets- Sheet 2 INVENTOR. ROBERT E.LINDEMANN AGENT R. E. LINDEMANN LITHOGRAPHIC DAMPENING MECHANISM AND METHOD Nov. 24, 1959 S Sheets-Sheet 3 Filed Nov. 27, 1957 INVENTOR. ROBERT E. LINDEMANN AGENT United States Patent ce LITHOGRAPHIC DAMPENING MECHANIS AND METHOD Robert E. Lindemann, Medina, Ohio, assignor to Harris- Intertype Corporation, Cleveland, Ohio, a corporation of Delaware Application November 27, 1957, Serial No. 699,316

12 Claims. (Cl. 101- 1'48) charging a predetermined amount of the liquid to its sur' face for subsequent presentation to a lithographic printing plate of the press.

Another object of the invention is to provide that such member be a roll constructed of individual transverse cells or sections, each cell having variable means for passing a measured amount of liquidto its surface, thus enabling control of the quantity of liquid across the width of the roll and ultimately across the lithographic plate.

A further object of the invention is to provide novel means for cleaning and draining the individual sections of the roll.

Other objects and advantages will be apparent from the following description in which reference is made to the accompanying drawings.

According to a preferred form of the invention, a hollow tube has concentrically mounted thereover with a space therebetween a series of porous bushings with means dividing the bushings laterally into individual cells. Liquid is communicated to and fills the space between the tube and each bushing. Between a supply for the liquid and each bushing is a pump which intermittently adds a preselected amount of liquid to the space between the bushing and roll and thereby displaces a like amount of liquid by passing it to the surface of the bushing. Liquid so passed to the surface is then transferred directly or indirectly to a lithographic plate to dampen the plate prior to its being inked.

In the drawings:

Fig. 1 is a fragmentary elevational view of a preferred form of the invention.

Fig. 2 is a fragmentary elevational view on a larger scale taken looking from the left side of Fig. l.

1 Fig. 3 is a fragmentary view somewhat similar to the left end of Fig. 1, and is taken along lines 33 of Fig. 2.

Fig. 4 is an enlarged detailed view of a pump constituting a portion of the invention.

Fig. 5 is a simplified side elevational view illustrating one type of dampening roll arrangement with which the invention may be used.

Fig. 6 shows another dampening roll arrangement with which the invention may be used.

Referring now to Fig. 1, spaced side supports 10 and 11 of a lithographic printing press rotatably support a tube tube 12 and fixed thereto.

or roll 12. The tube has mounted at one end thereof a rotary union 18, the purpose of which will be described v later. The pipe 17 rotates with the tube 12 when driven by the gear 14. On the opposite end of the tube is mounted a pump assembly 19 into which is threaded a plurality of piston assemblies 20. For reasons which will become apparent later, the piston assemblies are spaced equidistant around the assembly 19 and are located in planes offset axially with respect to the tube 12. The pump assembly 19 comprises a first cap 21 fixed to the tube 12, a chambered annular member 22, a cap 23 secured to the chambered annular member, and an end piece 24 secured to the cap 23. A short length of pipe 25 is threaded into the end piece 24 similarly to the connection at the opposite end of the tube. The pipe 25- comprises a portion of a rotary union 26 through which liquid from a supply tank 27 (shown schematically) is communicated to the exterior of the portion of the tube 12 between the side supports10 and 11 as will now be described.

The dampening medium of the present invention, that is, the means which actually supplies liquid to the litho graphic plate of the printing press is shown generally as a roll 28. In the preferred form of the invention, this dampening medium comprises a plurality of porous bushings 29 mounted between rings 30 spaced axially onthe It will be noticed that each of the porous bushings 29 is counter-bored at its ends in order to properly fit over the rings 30. The porous bushings may be made of cast metal powder such as *Oilite stainless steel. A cover 31 fits over the bushings 29 and is made of the material known as Molleton in the trade. It will be shown in another modification of the invention however that the cover 31 is not an essential part of the invention.

The bushings 29 are concentric with the tube 12 and have a space between them and the tube. Communicating from each individual cell to the cap 21 is a pipe 32. The pipes are spaced around the interior of the tube 12 and are fastened to the cap 21 by welding or other means. In the form ofthe invention shown, there are eight such pipes and eight bushings 29, dividing the roll crosswise into eight individual cells. Angularly offset openings 33 are provided in the cap 21 and corresponding openings or chambers 34 are provided in the annular member 22. The openings 33 and 34 communicate with their respective pipes 32.

Ink repellent dampening material in the supply tank 27 is communicated by gravity or pump through piping 35 to the rotary union 26, through the pipe 25 to a chamber 36 counterbored into the end piece 24. The chamber 36 encompasses all of the openings 34 in the annular member 22. Intermediate the member 22 and the end piece 24 is a filter 37 for preventing entrance of foreign substance into the roll proper. This filter may be dispensed with under certain circumstances where it is'not needed or desired to be used.

Each of the chambers 34 is provided with one of the piston assemblies 20, a one-way inlet valve 38, and a oneway outlet valve 39. The piston assembly 20 comprises a piston 40 which is spring urged in one direction and cam urged in the opposite direction by means to be subsequently described. The piston 40 is positively actuated to displace a portion of the liquid in the chamber 34so as to pass the displaced amount through the outlet valve 39 and then through the corresponding opening 33 in pipe 32 to and through the proper porous bushing 29 to dampen the cover 31. On its return stroke caused by the action of a spring 41, the piston will draw through the inlet valve 38 from the chamber 36 a sufiicient amount of the liquid to maintain that particular chamber 34 completely full. It will be seen that each of the chambers of the roll 28 may thus be provided with what amounts to an intermittent pressure so as to pass a predetermined amount .of liquid through the porous medium of the bushings 29, To

Patented Nov. 24, 1959 determine the amount of liquid so passed, a cam shoe 42 is provided to be engaged by the stem of the piston 40. The stem extends radially outward from the annular member 22. The camshoe may be radially adjusted in andoutby means of a thumb nut 43 threaded onto a c-amcarrier 44 which supports the cam shoe 42. This mechanism will be described in more detail in the descrip tion ofFig. 4.

When a printing job has been completed the roll may be cleaned as follows. A supply of air pressure is communicatedto apipe 45 having a shut-off valve 46. When the valve 46 is opened, air under pressure will pass through the rotary union 18 and theshort pipe 17 to the interior of the tube 12. For each cell or chamber in the roll, i.e. the sections between the several rings 30, there is provided a one-way valve 47 opening from the interior to thej exterior of the tube 12. A petcock 48 for each opening33 is opened to permit draining. of. the liquid from within the roll. A collector 49 having a funnel, top 50 is located to align with the petcocks 48'. When draining, the petcocks are opened one at a time, that one directly pointing. downwardly toward the funnel 50 being opened and the roll being maintained stationary. The air pressure then passing through the pipe 45 communicates to the interior of the tube 12 and acts to open the valve 47 so as to blow air through the valve. This causes liquid in the chamber to pass through its pipe 32 to the opening 33 and then out through its petcock 48. Each of the pipes 32 has a radial portion 51 which ends very closeto the inner surface of the bushing 29. In this fashion, when air pressure isv introduced into the area normally filled with liquid, almost all of the liquid is passed out through the portion 51 of the pipe 32. When so cleaning the roll, liquid ismaintained in the chambers 34 of the annular member 22 since the one-way valve 39 will permit passage of the liquid in only one direction. Referring now to Fig. 2, roll' 28 may run in contact with a plate mounted on a plate cylinder 52. Also running in contact with the plate cylinder are a plurality of the customary inking form rolls 53. A vibrating storage roll 54 receives ink through a train of rollers from an ink fountain (not shown) and passes the ink to the form rolls 53. The rolls 53 lay the ink. onto the plate on the plate cylinder 52 after the, dampening means has dampened the surface of the plate.

Carried, on the framework of the printing press is the dampening unit of which the present invention is a. part. A rack 55 is fixed to a frame 56 of the machine at each side thereof. A dampening unit is mounted to be movable toward and away from the plate cylinder 52 as a unit by providing that a pinion 57 in mesh with the rack 55 at each. end of the machine enable the entire dampening unit move as a. carriage. The pinions 57 are keyed to a shaft 58 extending parallel to the roll 28 and are journaled in side members 59. A handle 60 is also fixed to the shaft 58 and may be turned so as to cause the pinions 57 to ride on the racks and move, the dampening unit to and from. the plate cylinder. A notched annular piece 61 is fixed to the shaft 58 and is adapted to receive in its notch 62. a detent 63 which is spring urged radially inward of the shaft" 58'. The detent 63 is mounted for endwise movement in a bracket 64 carried on the member 59 on the leftjside of the machine as viewed in Fig. 1. The angles in the notch 62 are such as will permit the detent to be urged outwardly from the notch 62 by applying a sufficient. amount of pressure to the handle 60 to move theunit to: and from the plate cylinder 52. Riding on. the pump assembly 19 but maintained against rotation is: a cam shoe holder 65. It has sides 66 and 67 and a concentric portion 68 (see Fig. l). The shoe holder 65 is maintained against rotation by being provided with an ear 69'having a slot 70 which encompasses a protruding end of a rod 71 extending laterally outward from the member 59.

It will be seen in Fig. 2 that there are eight piston as- 4 semblies 20, a like number of the openings 34 in the annular member 22, and a like number of cam shoes 42 with their adjusting means. It will be seen that each piston assembly 20 is radially outward of one of the chambers 34. The thumb nut 43 used to adjust each shoe 42 is knurled to permit its hand adjustment. To provide for even application of the dampening fluid across the individual sections of the roll 28, a vibrator roll 72 may be provided. Vibration of this roll is effected from the vibration of the-roll -54 engaging the form rolls 53 of the inker. A frame member 73 of the inker has a projecting portion which carries a block 74 extending outwardly parallel to the tube 12. A, lever 75 is pivoted on an upwardly directed pin 76 in the block 74 and carries at its opposite end a roller 77 riding between the sides of a collar 78. The collar 78 is mounted on the end of a shaft 79 extending outwardly of the vibrating storage roller 54. As shown in Fig. 3, the lever 75 has a bifurcated portion 80 between the arms of which is mounted a pin 81 on which is journaled, a lever 82. The lever 82 carries at its outer end a roller 83 which fits between the sides of a collar 84 mounted on a shaft 85 fixed to the vibrator roll 72. The roll 72 is journaled in bearings 86 only one of which is shown in Fig. 3. The bearings 86 are capable of floating and are urged toward the roll 28 by means of springs 87. The bearings 86 are carried on rods 88 which are fastened to blocks 89 by means of nuts 90. The blocks 89 are mounted on the framework of the dampening unit.

It will be noted that the rod 71 extends between the members 59 and is numbered across its length as shown in Fig. 3. These numbers correspond to the various sections of the roll divided by the rings 30 shown in dotted lines. It will be noted at the left of Fig. 3 that the screws that carry the cam shoes 42 are also stamped with a number to indicate which shoe corresponds to its section of the roll 28. Each of the nuts 43 is stamped with numbers which indicate the extent of the adjustment of its shoe 42 toward and away from the stem of the piston 40 of the piston assembly 20 to determine the amount of liquid pumped for each rotation of the tube 12 in accordance with the stroke of the piston. Pins 91 having points closely adjacent the side of the nuts 43 show the settings for the various sections of the dampening roll.

In a particular printing job, it may be found that one side of the subject matter to be printed will require very heavy ink and/or dampening solution whereas the other side will require only a little. The amount of liquid passed through the various sections of the dampening member may be adjusted through the nuts 43. Obviously, the amount of solution supplied to the plate for any printing job can be controlled across the width of the plate.

Referring now to Fig. 4, it will be seen that the shoes 42 are carried on a member 92 which approximately comprises an inverted T. A pair of pins 93 extend radially outward of the center of the pump assembly 19 and are fixed in the arms of the T-shaped member 92. These pins are guided by holes 94 in the concentric portion 68 of the shoe holder 65. Springs 95 surround the pins 93 and have their ends abut the arms of the T and the bottom of a counterbore 96. It will be seen that adjustment of a nut 43 will move its cam shoe 42 in or out. The cam surface of these shoes is slightly eccentric with respect to the axis of the tube 12. In this manner the portions 97 of the pistons 40 will first ride beneath the cam surface of the shoe, will then engage the shoe and will be depressed gradually to provide an even pumping of the liquid from the chamber 34 to the surface of the porous bushing 29 with which that particular chamber corresponds.

Referring now to Figs. 5 and 6, other roll arrangements with which the invention may be used are illustrated. In Fig. 5', a pair of molleton rolls 98 run in contact with the plate on the plate cylinder 52. The roll 28 does not have .a molleton covering in this instance. While it is believed that this modification wilI perform substantially well, there is a possibility that with certain types of ink, the ink from the plate on the plate cylinder 52 may be picked up in part by the molleton coverings of the molleton rolls 98 and passed to the surface of the roll 28. In this fashion, it may be possible that the pores of the roll would be clogged to a limited extent.

In Fig. 6, the rolls 98 run in contact with the plate on the plate cylinder and in addition the customary metal vibrating roll 99 runs in contact with the two rolls 98'. The roll 28 in this instance runs in contact with the vibrating roll 99 to pass liquid from its surface to the roll 99 and thence to the molleton rolls 98 and the plate.

It has been found that if the dampening member 28 is covered with a zippered plastic covering overnight, the entire dampening mechanism will immediately start performing properly upon starting up the press the following morning. The usual filling of a roll pan and running the fountain for a somewhat lengthy period to printing has been overcome through use of the present invention.

Furthermore, while the preferred form illustrates a roll which is completely filled with liquid, a roll which is only partly filled will perform satisfactorily provided a partial vacuum is maintained on the liquid. While it is recognized that certain design difficulties may be encountered in producing such a mechanism, it is believed to be within the scope of mechanical skill and intended to be within the scope of the claims.

Various modifications may be made Without departing from the spirit and scope of the invention.

Having thus described my invention, I claim:

1. In a device for applying ink repellent dampening fluid to a surface to be dampened in a lithographic printing press, a rotatable tubular roll having a pervious wall, said roll having means forming a pluralityof independent enclosed chambers along its axis, a fluid supply, means communicating the fluid supply to each of the chambers, a fluid pump comprising a piston cooperating with the fluid to each chamber, said pumps being carried by the roll, means for operating said pumps as the roll rotates, and selectively operable means connected to said pump operatnig means for varying the length of stroke of each piston and consequently the quantity of liquid passed to the surface of the roll from each chamber.

2. A device according to claim 1 including a supply chamber in said roll on the fluid supply side of the pistons, and a rotary union connecting said supply chamber with the fluid supply.

3. A device according to claim 1 wherein each piston is axially offset from the others along said roll, and wherein said pump operating means includes a stationary cam for operating each piston as the roll rotates.

4. A device according to claim 3 wherein the selectively operable means comprises means for adjusting each stationary cam radially relative to its piston.

5. A device according to claim 2 including a one-way outlet valve intermediate each piston and its corresponding roll chamber and a one-way inlet valve intermediate each piston and the roll supply chamber, and means for draining the roll chambers.

6. A device according to claim 5 wherein the draining means includes a valved opening from each roll chamber to atmosphere, and means for applying pressure greater than atmospheric to each of the roll chambers.

7. In a device for applying ink repellent dampening fluid to a surface to be dampened in a lithographic printing press, a rotatable tubular roll having a pervious wall, said roll having a plurality of independent enclosed chambers along its axis, means supporting said roll for rotation on its axis, a fluid supply remote from said roll, a pump assembly mounted on and rotatable with said roll, a fluid chamber in said pump assembly, a rotary union and fluid conducting means connecting said fluid chamber with the fluid supply, said pump assembly comprising individual pump chambers connecting each roll chamber with the fluid chamber, a piston extending from each pump chamber radially outward of the pump assembly, a stationary cam for operating each piston as the roll rotates, each cooperating piston and cam being axially offset with respect to each other pair of the same, and means for adjusting each cam radially relative to its piston.

8. A device according to claim 7 in which a check valve is provided on the intake and outlet side of each pump chamber, and in which the roll chambers, pump chambers, and fluid chambers are maintained completely full of fluid during operation of the device.

9. A device according to claim 7 wherein said pervious roll is made up of short tubular sections generally corresponding in length to the length of each roll chamber as measured along the axis of the roll, and wherein said short sections are supported on an inner impervious tubular roll extending between supporting means located outwardly of the short sections.

10. A device according to claim 7 wherein the pump chambers are formed in an annular member comprising a portion of the pump assembly, and wherein the pump chambers are spaced equidistant from the axis of the roll and from each other.

11. A device according to claim 8 including means for opening each of the roll chambers to atmosphere, and air pressure applying meansconnected to the roll chambers for forcing liquid from the chambers outwardly through the openings for draining the roll at the outlet side of the pump chambers.

12. A device according to claim 11 wherein the pervious roll is supported on an inner impervious tubular roll extending between supporting means located outwardly of the pervious roll, and wherein a plurality of check valves one for each roll chamber are provided in said inner tubular roll, said inner roll being connected to the air pressure applying means whereby increased pressure in the inner roll will open the check valves and force liquid in the roll chambers outwardly through their respective openings when opened.

References Cited in the file of this patent UNITED STATES PATENTS Takats Feb. 13, 1940

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