US3007406A - Rotary printing machines for printing sheets in a plurality of colors - Google Patents

Description

Nov. 7 1961 A AL 3,007,406

ROTARY PRINTING MACHINES FOR PRINTING SHEETS IN A PLURALITY OF COLORS 3 Sheets-Sheet 1 Filed Sept. 7, 1960 II II III ll Nov. 7, 1961 P. PAPA ET AL ROTARY PRINTING MACHINES FOR PRINTING SHEETS IN A PLURALITY OF COLORS 3 Sheets-Sheet 2- Filed Sept. 7, 1960 3,007,406 TING 3 Sheets-Sheet 5 No 7, 1961 P.-PAPA ET AL ROTARY PRINTING MACHINES FOR PRIN SHEETS IN A PLURALITY 0F COLORS Filed Sept. 7, 1960 Fig. 6 6 7a United States Patent 7 3 007,406 ROTARY PRINTING lVIACHINES FOR PRINTING SHEETS IN A PLURALITY OI COLORS Paolo Papa and Federico Capetti, Tlll'lll, Italy, asslgnors to Nebiolo Societa per Azioni, Turin, Italy 1 Filed Sept. 7, 1960, Ser. No. 54,390

Claims priority, application Italy May 18, 1960 1 Claim. (Cl. 101-183) printing element to the next. The sheets to be printed should, in other words, when passing thus from one element to the next, appear always in corresponding positions with reference to the printing cylinders, so that the successive colors may always be printed at the desired location in accordance with a predetermined marking. V On the other hand, andmore particularly in the-icase of machines incorporating a plurality of printing elements, it is necessary to solve a mechanical problem which consists in controlling separately each element or at least each group of, elements, so as not to subject the members controlling the first printing element -.to.,exaggerated stresses. V v V This latter problem is of considerable importance when the different printing elements are designedand executed in standard sizes, so asto allow the building up of a machine intendedufor printing any variable number of colors. Of course, under such'conditions, the difierent elements forming the machine being inserted in'series in a manner such thatthe movement is transmitted from the first element to the last element, said first element is loaded exaggeratedly with referenceto the lastelement, so that the conditions of operation of this first element are far worse than for the last element. I I

From the above disclosure, it is apparent that, in'the case of machines printing sheets of paper in a plurality of colors, there are two fmidamenta-liand opposedconditions to be satisfied, to wit: the necessity of ensuring a perfectly accurate connection between the different elements of the actual machine, with a; view to obtaining an accurate registry of the successive colors printed, and the necessity of controlling separately each element, with a view to distributing uniformly .the load between the transmission means acting (more different elements.

The invention has consequently for its object the execution of a rotary machine for the printing of several colors on a sheet of paper, which machine satisfies both said above-disclosed requirements.

I According to the invention, the printing machine includes a dual transmission, of which one is adaptedto transmit movement froma controlling power unit to each of the printing elements of the machine or to each group of such elements, while the other transmission is adapted to ensure a perfectly accurate transmission between the successive printing elements and includes a gearing constituted by a plurality of cylindrical gears, of which one forms a special gear having a series of corrected teeth distributed in a first area in which the teeth project by a constant maximum amount and in a further area in which the teeth project by amounts which decrease first 3,007,406 Patented Nov. 7, 1961 2 W down to a and then increase back to said constant maximum value. g v I The clearance formed in the gearing between the corrected teeth of said special gear and the adjacent, gears I may advantageously be larger in the case of the invention than-the sum of the clearances appearing between the teeth of the different members ensuring the transmission of power to the successive elements 'orgroups of printing elements. In other words, and in accordance with the invention, the modifications of the projections of the teeth of said special gears are such that they produce, while the teeth are engaged, a clearance, the magnitude of which ensures at every moment, as concerns the control of the printing elements, an interruption in the gearing, of which said special gear forms part. Thus, the control of the printing elements may be performed solely under the action of the transmission provided for this purpose, while the succession of the gears ensures constancy of the relative position of each sheet as it passes from one element to the next. I Further features and advantages of the invention will appearin the reading of the following detailed descrip* tion of an embodiment of said invention, reference being made to the accompanying drawings given by way of a mere non-limiting example. In saiddrawings;

FIG. 1 is a diagrammatic elevationalview of a printing machine designed according to the invention and provided withtwo printing elements.

FIG.. 2 is a plan view thereof. FIG. 3 is a diagrammatic view of the gear provided withcorrected teeth forming part of the gearing interconnecting the printing elements. I v I FIGS, 4 and 5 illustrate two successive stages ofthe meshingbetween the special gear with corrected teeth and the associated gears. FIG. dis a plan viewof FIG. 5. i In the drawings, -1 and; 2 designate the two. printing elements including each a printing cylinder 3 cooperating with a rubber cylinder 4 which is, in its turn, in contact with a further cylinder carrying asuitably cut plate which is inked by rollers which are not illustrated. i I Between thetwo pri'nting cylinders 3 of the elements 1 and 2 are inserted sheet-transferring cylinders, resp tively at 6, 7 and 8. r .1

The'printing cylinders 3 of the elements 1 and .2 are subjected separately to the driving power. of an electric motor, for instance, which is not illustrated, the transmission being performed through a shaft 9 carrying two pairs of bevel wheels 10 and 11 adapted to control each one'of said printing elements. The cylinders 3 of the elements 1 and 2 and the transfer' cylinders 6, 7 and 8 are also interconnected by the kinematic system including the gears 3a,,3b, 6a, 7a,- 8a, whichgears are keyed each to the shaft of the corresponding cylinder.

* the elements 1 and 2 by means of a guiding table T after removal of. a pile of sheets carried inside a suit-able container 12. After printing,the sheets are driven'by means known per se includinga transmission belt C, so. as to be stacked at a collecting station, which is not illustrated.

The passage of the sheets from one element to the next is ensured by transfer cylinders 6, 7 and 8 includmg each clamping means 13-14 adapted to engage the successive sheets. In order that the position of each sheet may not be modified during its transfer from one position to the next, it is essential that there should be no clearance between the gears engaging each other at the moment of transfer.

If the transmission is ensured in the conventional manner by means of normal gears, this obviously forms a permanent possibility of transmitting power between the different cylinders of the printing machine.

The sheets to be printed are fed to i n the contrary, in the case of the invention, the trans mission of power is prevented by the presence of a gear such as the gear 7a corresponding to the transfer cylinder 7, said gear showing a suitable series of corrected teeth distributed between a first area having an angular breadth (p of a suitable value, in which area the teeth project by a constant maximum value and a furtherarea in which the projection of the teeth decreases according to a predetermined law when considered along the periphcry of the gear in the direction of the arrow F, so as to reach a minimum value in a section of last-mentioned area diametrically opposed to the first area having for its breadth an angle 1;: beyond which the projection increases in accordance with a similar law, so as to return to its constant maximum value.

In the example illustrated, the law of modification of the projection of the teeth is linear, but this law of variation should not be considered as limiting the scope of the invention as defined in the accompanying claim.

The gear 7a with corrected teeth is keyed to the shaft of the transfer cylinder 7 in a manner such that the arc subtended by the angle 9; maybe arranged centrally with reference to the opening 14 of the clamping means carried by the cylinder 7, so that, during the transfer of the sheet during which the openings of the clamping means of two successive cylinders lie on a straight line extending perpendicularly between the axes of the cylinders, there may be no clearance at all between the teeth of the gears on the transfer cylinders 6 and 7 which serve for shifting the sheet.

In contradistinction, during this stage, the gear 7a shows the teeth which have the amount of projection in the section diametrically opposed to the area ensuring the transfer, so that it engages the gear 8a with a clearance such that the transmission of power is obtained then through thetransfercylinder 8 to the. second printing element, by means of the actual transmission including the shaft 9 and the two bevel wheels 10 and 11.

FIG. shows a subsequent stage of interengagement between the three gears 6a, 7a and 8a carried by the cylinders 6, 7 and 8 respectively. During the stage illustrated in said FIG. 5, the transfer of sheets is about to be made between the cylinders 7 and 8; at such a moment, a meshing without any clearance is obtained between the teeth of the gears 7a and 8a on the cylinders 7' and; 8, while the maximum clearance in the meshing is obtained between the gems 6a and 7a.

Thus, perfect synchronism is ensured between the movements of the cylinders 7 and 8 and this leads to a correct transfer of the sheets to be printed under the ac,- tion of the clamping means carried by each of the cylinders. In all cases, and although the teeth meshing without any clearance between the teeth of the corrected gear 7a and the teeth of the adjacent gears are shifted towards the left and towards the right alternatingly, yet, the distance I separating the axis of the corrected gear from that of each of the adjacent gears does not vary, since, as already mentioned, the clearance in the gearing is obtained by a suitable correction of the teeth of said S In the example illustrated, the printing machine. is constituted by a system of two printing elements interconnected by the kinematic means described hereinabove, and it should be well understood that said embodiment should not be construed as limiting'the scope of the invention as defined in the accompanying claim and the printing machine according to said invention may inclnde any variable number of printing elements or groups of printing elements driven by means of a power transmission.

Obvious, the fact that it is possible to clearly separate for the transmission of power the various elements forming the machine, allows executing such elements in accordance with uniform standards and, thus, a number of said elements may be associated so as to produce a machine adapted to print any desired number of colors.

Of course, the details of the execution and control of its parts may be considerably modified with reference to what has been described and illustrated by way of a mere exemplitication, without unduly widening thereby the above-defined scope of the invention. I

What we claim is:

In a rotary multicolor printing machine, the combination of a plurality of successive printing units each designed for printing one color and each having an impression cylinder, a motor and transmission means interposed between said motor and said impression cylinders for rotating the latter, a number of cooperating transfer cylinders arranged between the impression cylinders of the successive printing units, sheet clamping means on said cylinders for taking up sheets from the preceding cylinders and feeding the sheets to the successive cylinders, a gear fastened to one end of each of said impression and said transfer cylinders, each gear being coaxial with the cylinder to which it is fastened being arranged on the same side of the machine andmeshing with the gears fast with the adjacent cylinders and transmitting rotary motion from said impression to said transfer cylinders, one of the gears fast with one, of said transfer cylinders being provided at its periphery with a first area in which the teeth project to a maximum extent and with a second area extending over the remainder of the periphery of said gear, wherein the teeth are formed inwardly of the position of the teeth of a theoretical gear provided along its entire periphery and having teeth projecting to said maximum extent, the projection of the successive teeth along said second area varying according to a desired law in one half of said second area between saidabove mentioned minimum and maximum extentobtained at a point diametrically opposed to the middle of said first area, then again increasing according to a law similar to the above mentioned law between the minimum and maximum extent in the other half of the second area, the clearance provided during engagement of the teeth of minimum projection of said gear with the gears fast with the adjacent cylinders being larger than the sum of the clearances in said transmission rotating said impression cylinders, the position of the sheet clamping means on said one of said transfer cylinders and its angular shift with, respect to the adjacent cylinders being such that said clamping means are arranged in sheet exchange position with the clampingmeans of one of the adjacent cylinders when the middle part ofsaid first, area lies at the level of the plane extending through the axes of said cylinders.

References Cited in the file of this patent UNITED STATES PATENTS I,62I,607 Sharpless Mar. 22, 1927 2,115,975 H'arrold May 3, 1938 2,484,905 Peyrebrune Oct. 18, 1949

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