US2231694A - Dampening apparatus - Google Patents

Description

Feb. 11, 1941- a. D. STEVENS DAMPENING APPARATUS Filed May '7, 1958 2 Sheets-Sheet 1 INVENTOR. Biz/6'3 Sfiezrens BY I ATTORN Feb. 11, 1941.

B D. STEVENS DAMPENING APPARATUS Filed May 7, 1938 2 Sheets-Sheet 2 ATTOR Y5 Patented Feb.- 11,1941

PATENTY OFFICE 2.231.694 mmranmc arrmrus Burt 1). Stevens, Chicago. Ill. seals-nor to Miehlc l'rintingrresaamanufactnring cm, 111., a corporation of- Illinois Application May 1, 193a, No. 206,566

1 Claim. (01. 101-141) This invention \relates to dampening mechanism for lithographic printing presses and other repr ucing apparatus of the planographic class.

It has particular reference to dampening devices which will selectively measure and maintain conv 15 such non-printing parts should be restricted to a minimum, because if, the film of moisture is too heavy then the surface of -*"the-plate will become iiloodc noticeably so in those areas which representthesolids and darker tones of the subject.

- In such cases the dampening fluid will spread beyond the non-printing areas and consequently some of the ink that should adhere to the printing image, will be repelled and in part become .emulsifled with dampening fluid, thereby seri- =25 ously impairing the quality of the printing to be produced.

in the use of dampening devices heretofore mourn, it has been found that it is extremeLv cult to control and maintain constant the 30 desired volume of dampening fluid during the printing of a job. I refer in particular to such devices which include a water fountain, a fountain roller, usually of metal and arranged to rotate within the fluid, in said fountain. a ductor 35 roller covered with material such as molletonand alternately contacting said fountain roller, a distributing or vibrating roller having a metal surface and to which moisture is transferredby said ductor roller, andone Or more dampening rollers 40 also. covered with molleton and contacting with said distributing roller and the printing plate in g'der to apply the ink repelling fluid to the lat r.

Not only is it difficult with arrangements of this class to control and maintain constant the fllin of ink to'be applied to the printing plate, but other drawbacks are inherent in such devices For instance, the dampening roller or rolls which, during the printing operation remain in contact with the printing surface, will pick up ink that remains on the plate after an impression has been pulled. Consequently ink eventually becomes transferred through the intermediary of able for the purpose for whichthey are intended. The resultant clogging with ink of the molleton covered rollers will necessitate interruption of the printing operation in order to replace or recondition the ink saturated rollers and per-- haps also, to replace the fluid in the fountain because of the ink that has become emulsified with the dampening fluid. I

It is therefore one' of the main objects of my invention to provide means whereby all of the defects hereinabove referred to shall be eliminated. This I accomplished by an arrangement whereby the fllm of moisturethat is to be applied to the non-printing portions of a planographic printing plate may be reduced to a mini- 1 mum. and can be positively controlled and maintained constant during th productive'period of a press.

Another object of my invention resides in the provision of means whereby the, required volume of dampening fluid can be predetermined and metered for every printing cycle.

A further object is to provide means which will prevent ink and other impurities from becoming transferred to the fluid in the fountain of the dampeningmechanism.

Amorc specific object is the provision of mechanism whereby the volume of fluid to be supplied to the printing plate can be readily varied while the press is in production to exactly suit each individual Job. I 1

A still further object resides in providing a dampening device which will be simple in its construction and convenient to manipulate.

These and other objects will be apparent from 5 the accompanying description, claim and attached drawingswhich exemplify one preferred embodiment of my invention, and in which drawlugs:

Figure 1 is a diagrammatic viewin side eleva- 1 tion showing the general arrangement of the cylinders and associated parts in a conventional type of planographic offset press to which Ihave applied my invention:

Figure 2 is a partial, sectional front elevation of the arrangement illustrated in Figure 1. but showing merely those parts which apply more speciflcally to the dampening mechanism;

Figure 3 is a cross section of one form of device whereby the volume of fluid to be supplied for dampening the printing plate, can be accurately metered, the section being taken along line III-IIIofFigureil:

Figure 4 is a view similar to Figure 3 but showing certain parts in different positions; and 5s uid supplying device, similar for instance to those disclosed in United States Letters Patents 1,855,516 and 1,874,961 issued to R. J. Gits, wherethe principle of my invention may be carried out, other conventional arrangements for metering fluid, and which are readily available to the trade and quite generally used for dispensing a lubrieating fluid-for the purpose of applying it to various parts of a machine, may be adopted with equal results and without departing from the basic featureof my invention.-

Referring flow to Figure 1 of the drawings, the

planographic printing press in connectionwith which I have illustrated my invention merely by way of example, comprises a frame II in which are mounted a plate'cylinder ll, blanket cylinder l2 and impression cylinder It. The printing plate which is carried by the cylinder II and secured thereto in any well-known manner. is inked by means of a conventional inking mechanism which may include ink distributing rollers M to I! and form rollers l1.

Prior to receiving the ink the plate is dampened @for the purpose explained herein. The roller system whereby this is accomplished may comprise a molleton covered roller II, a vibrating,

' i. e. distributing roller is and one or more dampening rollers 25 which also are covered with molleton or kindred material; I

in the operation of a-press of this class the ink is transferred from the inked plate to an offset blanket which is stretched over and held secure on the cylinder l2. Sheets to be printed are .fed along afeed board 2| to sheetholding elements on the impression cylinder it. Any well known means, notshown, are provided'for registering the sheets priorto being engaged by the hclding-elements on the impression cylinder.

The-ink image that has been applied to the blanket cylinder II will be transferred i. e. oifset onto a sheet as it is carried between the latter cylinder and the impression cylinder It. The

delivery of the printed sheet is then accomplished in the usual way.

The general arrangement of the dampening apparatus which embodies my invention is illustrated in Figure 2. It includes a self-contained, preferably completely closed fountain 55 within which is housed a unit' of closely. adjacent fluid metering and dispensing device ll, see Figure 5. These may be arranged in a single row, or they can be placed in oilset relation to each other so that the fluid dispensing nozzles 32 will be as closely together as possible to thereby assure I an evenand complete distribution of dampening fluid over the entire surface of the roller l5 and subsequently over the roller or rollers 25.

Concerning the detail construction of the fluid metering and dispensing unit, I indicated herein that any available standard devices may be utilized. In Figure 3 I have shownthe cross section of a preferred form of one device of which theunit in the fountain maybe made up. The relative arrangement of the series of such devices is more clearly illustrated in Figure 5.

As shown in Figure 8, the bottom plate of the fountain 30 is provided withtapped bores 53 into which are threaded the stationary, inner tubes 55 of the meteringv and dispensing devices. These tubes may be locked in position by means of a I lock nut 35. A second tube 55' is arrang d to freely slide over the inner tube 34 so that it may inner 'tube 35 i. e. dispensing nozzle 52.-

The means whereby the tube 35 may be raised and lowered includes a collar 59 with an annular recess 45. In the front wall ll of the fountain there are provided a series of bores 42, one for every metering device. Each one of these, bores retains an adjusting knob 53 which ,is'free to -rotate within the bore andheld in position by means of a pin or key 44 engaging an annular groove 45 in said knob. Parallel to its axis and projecting from near the periphery of the inner face ofthe knob 45 is a pin 48 which engages the annular groove in the collar 39. The front face of the adiusting knob is formed with an axial slot 41 which, however, does not extend across the entire width of the front face, see Figures 8, 4 and 5, for reasons that will become apparent later.

The adjusting knob 48 may be held in its various positions by means of a spring actuated friction pin engaging corresponding notches formed in said knob. i

For metering the fluid that is to be fed to the roller I5, I propose to use a series of cups 50 which are normally submerged in the fluid within the fountain 30. One of such cups is associated with each one of the metering d vices and they are all mounted on a bar II which stands lengthwise within the fountain. In orde'n to raise and lower said bar, and therewith the cups 50, I provide a plunger 52 which is bolted at 53 to the bar 5|, see Figure 5, and extends upwardly through a bore 54 in the cover plate 49 of the fountain 30. At its upper end the plunger 52 is provided with a stem 55 which extends through a housing 56 bolted to the cover plate 49 or otherwise secured to the fountain. The plunger 52 is urged downwardly by means of a compression spring 51 of course be actuated in any suitable manner either'by separate driving mechanism or by' a moving part of the press. I' have illustrated in Figures 1 and time preferred, simple way of transmitting motion to the plunger 52, namely by means of a bell crank lever III which is pivoted at 5!. The end 52 of said-lever engages within a slot 53 provided at the upper end of the stem 55, while the free end of the other arm of the lever "is pivoted to a connecting rod 54 which extends downwardly and is attached to any moving part of the press whereby reciprocating mo- .tion will be imparted to said rod in proper timed relation.

It is preferable of course to provide some means whereby the level of the fluid in the fountain 55 thefluid metering and means de-,

scribed, the volume of substance that is to be applied to the roller It, can be accurately predetermined and maintained constant thro ghout the printing of a job. Each individual metering device can be independently adjusted so that the volume shall be varied gradually from nil to the maximum volume of fluid that the cups 50 can retain. This is readily accomplished by inserting a flat piece of metal into the slot 41 in the face of the knob 43 and then turn the latter to the desired position. when the open part of the slot 41 points upwardly as shown in Figure 3, then the supply of fluid will be nil.

By turning the knob into diflerent positions I,

II, III or IV the volume of fluid to be dispensed by the nozzles 32 will varycorrespondingly, it being the maximum when the open end of the slot points down, namely in position IV. As more clearly shown in Figure 5, thelocation of the outlet slot 38 in the tube 38 will vary ac,- cording to the extent the knob 43 is turned, and therefore the volume of fluid to be emptied from the cups 50 into the slots 3!, when the plunger 52 is brought into its uppermost position, will vary correspondingly, see Figures'4 and 5.

I have indicated herein that any suitable metering devices, other than the type described above, may be used for the purpos of carrying out my invention without departing from its basic principle; therefore, I wish it to be under! stood that it is myintention to cover any modiflcations in the general arrangement of my scheme that will come within the scope of the appended claim.

I claim:

In dampening apparatus .for pianographic printing presses or the like, the combination of a set of fluid distributing rollers, a fluid feeding unit comprising fluid expelling devices arranged to supply dampening fluid to one of said rollers, metering elements associated with said devices for selectively determining the volume of fluid.

to be supplied to difl'erent portions of said rollers, means to adjust said metering elements, means to actuate said expelling-devices at predetermined intervals to supply measured volumes of fluid, and means for maintaining the fluid in said unit at ,a constant level.

BURT D. STEVENS.

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