US2510388A - Method and means for the polychrome offset printing - Google Patents

Description

June 6, 1950 u urr 2,510,388

METHQD AND MEANS FOR THE POLYCHROME OFFSET PRINTING Filed Jan. 20, 1947 2 Sheets-Sheet l June 6, 1950 G. DUBUIT 2,510,388

METHOD AND MEANS FOR THE POLYCHROME OFFSET PRINTING Filed Jan. 20, 1947 2 Sheets-Sheet 2 Patented June 6, 1950 METHOD AND MEANS FOR THE POLY- CHROME OFFSET PRINTING Louis Gilbert Dubuit, Paris, France lApplication January 20, 1947, Serial No. 723,021 In France May 25, 1946 10 Claims.

The polychrome off-set printing including the successive transfer of a plurality of monochrome the grade of the ink t be-used. As a matter of fact, if the inks of various colors which areto be used for printing are all=of the same kind and of the same viscosity; there is produced on the blanket during thaexectitionof the machines to be printed mixtures betweenlthe colors which blend together so that it is necessary to speedily stop the operation inorder to clean-the blanket andthe plates. In order to 'avoid'this drawback one is led touse' for each color ink thenature and the viscosity of which are sufliciently different from those oftheinks of'the other colors forsuch mixings of the colors to become impossibleythis leads to a considerable complication andrestricts substantially the field of application of the printing"methodponsidered.

My invention has for its object a method which allows removing the-above' 'drawbacks whereby it is possible to use for polychrome cit-set print ing, printing inks ofany 'type without-it being necessary to take into account their nature or their relative visco'sities. My improved'method consists chiefly in eliminating from each plate after each'transfer operation of said p'late on to the blanket and before any'further inking of said plate theink which is still adherent to the latter after the transfer operation.

It has been found as-a matter of'fact, that such a cleaning of the plate between the successive transfers is sufiicient to prevent any objectionab le mixing between the colors. This cleaning may be executed by means of a roller of rubber orthe'like material similar to the rollers in current use for hiking the plates, said rollers being merely moved over the plate after the transfer operation, while the inking roller or rollers are held" away from said plate. The ink which still adheres to the latter -is then collected by the rollerfrom "which it "may -'-be removed for instance-by a scraper.

The method according-to my invention-is of particular advantage in rotary machines of a type known; per -se which are adaptedfor the-offset printingon cylindrical and the like objects, for instance, such as tubes.

In this case/the plates and the blankets are wound respectively over correspondingcylinders, the blankets rolling'in:contact-with all-the plates in" succession. "The-arrangement forexecuting the inventionmay then include 'fore'achmono chrome platea rocking support'pivotaily secured to'the frame of the machine to be'printed and carrying on one hand an inking roller 'and'onthe other hand, a cleaning roller. The rockingof said support bring alternatingly 'thetwo' rollers into contact with'the plate considered, said support cooperating with a cam rigid with the cylinder carrying the blanket and producing 'the rocking of said support during thepassage of the plate" in contact with blankets and during a'fraction of the rotation of the blanket carrying cylinder preceding saidpassage; this rocking is performed in the directionbringing the inking roller into contact with the. plate and itis :again provided during the 'remainderof theflrotation of the cylinder "considered in the oppositedirection'which brings the cleaning roller into contact with the plate, a'return spring connecting :the rockingsupport'with the frame of the ma'chine and urging said support into contact'with the cam.

"It is of advantage to proce'ed'with-the adjust* ment of the" pressure urgingthe rollers against the plate at least as concerns the "inking.- roller. To this purpose, the latter roller or the two rollers used for inking and cleaning;maybe-mounted for instance, in an adjustable mannerzron-their rocking support. It is however preferable .to'use a suppoitmade of two independent'rparts;":say two arms which are advantageously pivotally secured to a common'shaft and which .are' connected through a spring or the like elasticme'ans urging them towards one another while at least one adjusting screw is provided forlimiting the stroke of either of the arms carrying'the inking roller of both the arms formingthe"rollerfisupports. In the case of a single screw, "the latter maybe rigid with the arms carrying'theinking roller and cooperate with a'stopparriedby the arm carrying the cleaning roller or reversely. In the case of two adjusting screws',"the latter are preferably carried each by the 'c'orrespondingiarm and cooperate with a stationary stop carried by the frame of the machine, projections carriediby each arm cooperating with one anotherfor-lprovidinga minimum spacing b'etween the :latter, which spacing should be sufficiently'large for the two rollers to be incapable of coming -simultaneously into contact with' the plate; the -arrangement of two adjusting screws allows a modification as desired of the pressures exerted on the plate by each of the inking and cleaning rollers.

The rocking support carries -preferably a scraper adapted to cooperate" with the cleaning roller, said member being for instance constituted by a mere blade carrying a bucket adapted to receive the ink removed from the roller considered.

I have shown diagrammatically in accompanying drawings a form of execution of an arrangement according to my invention as applied to a rotary machine for three color off-set printing on objects such as tubes, for instance of carboard or aluminium.

In said drawings:

Fig. 1 is a general diagrammatic view showing the mounting of several arrangements according to my invention on a printing machine.

Fig. 2 is a diagrammatical view at a larger scale of a single arrangement according to my invention.

The printing machine (Fig. 1) comprises as known per se a rotary cylinder I to a portion of the periphery of which is secured in the usual known manner a blanket 2 for the transfer of the impression. The cylinder I is mounted in the usual manner on a frame which is not illustrated and which includes radial supports 3, carrying in corresponding bearings each a cylinder 4 carrying a printing plate 5 corresponding to one of the colors of the three-chrome printing.

To a shaft 5, rigid with each radial support 3 are pivotally secured two independent arms I and 8. The arm I carries an inking roller 9 of rubber of a type known per se, while the arm 8 carries a cleaning roller in similar to the roller 9.

The plate carryin cylinder t is adapted to rotate in a manner known per se, under the action of a gear cooperating with a toothed wheel rigid with the cylinder I. The roller 9 is mounted loose while the roller I is adapted to rotate at a peripheral speed which is equal to that of the plate under the action of a gearwork carried by the arm 8 and including a toothed wheel I! receiving its movement from the shaft I2 of the cylinder I also through the agency of a gearwork. The system of transmission members which has just been mentioned has not been illustrated in the drawings in order to not overcrowd the latter, but their mounting shows no particular difficulty and is within the scope of any mechanic.

The members for bringing ink to and distributing it over the roller Ill and the members adapted to hold the objects which are to receive the impression and to bring them into contact with the transfer roller, difier by no means from the similar members already used in similar machines in current use and they have therefore not been illustrated.

The arms I and B are permanently urged towards one another by a return spring I3 and carry respectively projections I 4 and I5 facing one another, said projections having a length such that when they are in contacting relationship they provide between the rollers 9 and III a sufficiently large spacing for said rollers not to be capable of comin simultaneously into contact with the plate 5. These arms carry also adjusting screws shown respectively at I6 and I1 and cooperating'each with one side of a common abutment I8 rigid with the corresponding support 3.

The arm 8 is provided with a scraper I9, the edge of which bears against the surface of the cleaning roller I0, said scraper carrying a bucket or recess 21? adapted to receive the ink scraped ofi the roller Ill. For sake of simplicity said scraper has been illustrated as stationary but it may be pivotally secured to its support and urged by a spring against the surface of the roller I0.

This same arm 8 which is urged towards the support 3 by a spring 2i carries at its free end a roller 22 cooperating with a cam 23 rigid with the cylinder I and cooperating with all the similar rollers 22 of all the inking and cleaning arrangements distributed over the periphery of said cylinder I. The outline of this cam is such that for each arrangement, the cleaning roller I0 is moved away from the plate 5 against the action of the spring 2| durin the passage of said plate over the blanket 2 and during the period preceding said passage which corresponds to about two revolutions of the cylinder 4 while during the remainder of the rotation of the cylinder I said roller I0 is submitted unrestrictedly to the return action of the spring 2 I The description of the operation of the machine given hereinafter corresponds only to the existence of a single plate carrying arrangement, the operation being the same for all these arrangements.

The cylinder carrying the blanket 2 is set rotating through the usual means in a direction given out by the arrow, and the plate 5 carried by the cylinder 4 starts also rotatin together with the rollers 9 and I0. When the cam 23 engages the roller 22 at the point 24 (Fig. l), the arm 8 is urged to rock against the action of the spring 2| and the roller I0 is moved away from the plate 5. The movement of the arm I being associated with that of the arm 8 by the spring I3, said arm I is caused to rotate clockwise until the adjusting screw I6 abuts against the stop I8. The screw I6 is previously adjusted so that under said conditions the roller 9 may bear against the plate with the pressure required for the correct inking of the latter. The plate 5, is then filled with ink of the required color, and when its passes over the blanket 2 is transferred on to the latter.

The cylinder i prosecuting its rotation, the cam 23 leaves the roller 22 at a point 25. The spring 2| urges then the arm 8 into contact with the cylinder. The projection I5 comes into contact with the projection I4 and urges it back so that the roller 9 is moved away from the plate 5, while the roller Ill bears against the latter, the screw I! being adjusted to this purpose. During the contact between the plate 5 and the roller ID, the latter collects the ink covering said plate, said ink being removed from the roller ID as it rotates by the scraper IS. The roller 22 is then reengaged by the cam 23 and the oper-- ation begins over again.

At each revolution of the cylinder I, the different plates are thus transferred on to the blanket, which is caused subsequently to move over the objects to be printed which assume, in a manner well known per se, a corresponding rotary movement, said object receiving then the impression transferred on to the blanket.

What I claim is:

1. In an arrangement for off-set polychrome printing applicable to rotary machines including a cylinder for the blanket and a plurality of cylinders for the plates to be inked in different colors and transferred on to the blanket, the combination with each monochrome plate carrying cylinder of a support, a stationary pivot to which said support is rockingly secured, an inking roller and a cleaning roller carried by said support and means whereby the rocking of the support brings in alternation the two rollers into contact with the plate, a cam rigid with the blanket carrying cylinder, and adapted to provide the rocking of atlases thersupnortvduringrthe -passagehitherplate over theblanket and during. a" fraction-of the rotation of the: blanket: carryin :cylinder preceding :said passage rin: a direction? bringingronerroiler into contact with the plate and a-spring connected withthe rocking support and urgingsaidsupport against the cam and blanket carrying cylinder for rocking the support in the opposite direction with reference to vthe'plate carrying cylinder and bringing the: other roller into .-contact with :the plate.

2; ,In; anarrangement .for offset polychrome printing. applicableto rotary machines includin a .cylinder for the-blanketv andza plurality of cylinders vfor theplates to be vinked indifferent colors and transferred onto the blanket-thecom- :binatiomwith each'monochrome plate carrying cylinder of: a'support, a stationary: pivot: to which saidisupportis rockinglysecured, an inking roller and. ascleaning roller ,carriedzby said: support, meansfor adjusting the pressure. ;applied by! at least the. inking roller-on the plate and-means whereby: the'rocking-ofnthe support-1 brings in alternation: .the two rollers into..-contact-.with the plate; .acam rigid 'withzthelblanket carrying cylinder, and adapted to provide the rocldng of the support durin the passage of the plate over the blanket and during a fraction of the rotation of the blanket carrying "cylinder preceding said passage in a direction bringing one roller into contact withltheplate and a spring connected with the rocking support and-urging said support against the cam and blanket carrying-cylinderflforrocking the supportcin the ;opposite direction with reference to the-plate, carrying cylinder and bringing the other roller into contact with the plate.

3. In an arrangement for off-set polychrome printing applicable to rotary machines including a, cylinder for the blanket and a plurality of cylinders for the plates to be inked in difierent colors and transferred on to the blanket, the combination with each monochrome plate carrying cylinder of two members, a stationary pivot for same, a spring urging said members towards one another, means for limiting the movement of the members towards one another, an inking roller and a cleaning roller carried respectively by each of the two members, a cam rigid with the blanket carrying cylinder and cooperating with one member for urging one of the inking and cleaning rollers away from the plate carrying cylinder and yieldingly engaging the other roller into contact therewith and yielding means urging the cam follower against the cam and blanket carrying cylinder surface beyond the cam and thereby urging the first cylinder into contact with and the second cylinder out of contact with the plate carrying cylinder.

4. In an arrangement for off-set polychrome printing applicable to rotary machines including a cylinder for the blanket and a plurality of cylinders for the plates to be inked in diiferent colors and transferred on to the blanket, the combination with each monochrome plate carrying cylinder of two members, a stationary pivot for same, a spring urging said members towards one another, an adjusting screw cooperating with at least one member, an abutment on the other member against which said screw is adapted to hear an inking roller and a cleaning roller carried respectively by each of the two members, a cam rigid with the blanket carrying cylinder and cooperating with one member for urging one of the inking and cleaning rollers away from the plate carryingscylinder. land yieldingly engaging-the other .rollerinto contact,,therewith-. and yielding means. urging ,the cam i follower against the .cam and-blanket- .carrying cylinder surf ace) beyond .thacam and,.thereby. urgingthe first cylinder into-contact (with and the'second cylinder out of contactwithtthe plate carrying cylinder.

v .5. In. an arrangement tor oil-set polychrome printing applicable to rotaryernachines includinga cylinder for the blanket and a plurality of cylinders for :the plates to-beinked in different colors andr transferred on to the blanket, the combination-i-with each monochrome plate carryinggcylinder-of: two members, a stationary pivot forsame; aspring urging said members towards one anothentwo adjusting'screws carried by the correspondingamembers, a stationary stop cooperating. with both screws projections facing one, another on-thetwo members and adapted to meet for preventing the spacing between said parts from falling underneath a predetermined value, an inking roller and a cleaning roller carriedrespectively'by each of the two members, a cam rigid with the blanket carrying cylinder and-cooperating with vone member for urging one of the. inking and cleaning .rollers away from the plate-carrying cylinder and'yieldingly engaging the other-roller into contactitherewith and yieldinglmeans urging the cam follower against the cam and blanket carrying cylinder surface beyond theca-m and'thereby. urging the first cylinderinto contact with and the second cylinder out of con tact with the plate carrying cylinder.

6. Inuanarrangement for ofi-set polychrome printing applicable to rotary machines including a cylinder for the blanket and a plurality of cylinders for the plates to be inked in difierent colors and transferred on to the blanket, the combination with each monochrome plate carrying cylinder of a support, a stationary pivot to which said support is rockingly secured, an inking roller and a cleaning roller carried by said support and means whereby the rocking of the support brings in alternation the two rollers into contact with the plate, a cam rigid with a blanket carrying cylinder, and adapted to provide the rocking of the support during the passage of the plate over the blanket and during a fraction of the rotation of the blanket carrying cylinder preceding said passage in a direction bringing one roller into contact with the plate, and a spring connected with the rocking support and urging said support against the cam and the blanket carrying cylinder for rocking the support in the opposite direction with reference to the plate carrying cylinder and bringing the other roller into contact with the plate, and a scraper cooperating with the cleaning roller for removing the ink therefrom.

7. In an arrangement for oiT-set polychrome printing applicable to rotary machines including a cylinder for the blanket and a plurality of cylinders for the plates to be inked in difierent colors and transferred on to the blanket, the combination with each monochrome plate carrying cylinder of two members, a, stationary pivot for same, a, spring urging said members towards one another, means for limiting the movement of the members towards one another, an inking roller and a cleaning roller carried respectively by each of the two members, a cam rigid with the blanket carrying cylinder and cooperating with one member for urging one of the inking and cleaning rollers away from the plate carrying cylinder and yieldingly engaging the other roller into contact 7 therewith and yielding means urging the cam follower against the cam and blanket carrying surface beyond the cam and thereby urging the first cylinder into contact with the second cylinder out of contact with the plate carrying cylinder, a scraping blade yieldingly carried by the same member as the cleaning roller and adapted to cooperate therewith and means rigid with said blade for collecting the ink removed by said blade from said cleaning roller.

8. In an arrangement for oiT-set polychrome printing applicable to rotary machines including a cylinder for the blanket and a plurality of cylinders for the plates to be inked in different colors and transferred on to the blanket, the combination With each monochrome plate carrying cylinder of a support, a stationary pivot to Which said support is rockingly secured, an inking roller and a cleaning roller carried by said support and means whereby the rocking of the support brings in alternation the two rollers into contact with the plate, a cam rigid with the blanket carrying cylinder, a cam follower carried by the rocking support for cooperation with said cam, and adapted to provide the rocking of the support during the passage of the plate over the blanket and during a fraction of the rotation of the blanket carrying cylinder preceding said passage in a direction bringing one roller into contact with the plate and a spring connected with the rocking support and urging said support against the cam and blanket carrying cylinder for rocking the support in the opposite direction with reference to the plate carrying cylinder and bringing the other roller into contact with the plate.

9. In a polychrome off-set printing method including the successive transfer of a plurality of monochrome plates on a single blanket; the steps of removing the plates from the blanket after each transfer operation, removing the inking cylinder from each plate when the latter is removed from the blanket and removing the ink from the plate by passing the entire surface of the plate at least twice in contact with a yielding roller of the plate inking type, and reinking said plate anew in contact with the blanket.

10. In a polychrome ofi-set printing method including the successive transfer of a plurality of monochrome plates on a single blanket, in which a plurality of blankets are mounted on the same blanket cylinder; the steps of removing the plates from the blankets after each plate has contacted all of the blankets, removing the inking cylinder from each plate when the latter is removed from the blankets and removing the ink from each plate by passing the entire surface of said plate at least twice in contact with a yielding roller of the plate inking type, and reinking said plate anew in contact with the first blanket.

LOUIS GILBERT DUBUIT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 752,896 Firm Feb. 23, 1904 1,743,656 Cox Jan. 14, 1930 2,106,104 Massey Jan. 18, 1938

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