US2875688A - Web control means for rotary offset web printing presses - Google Patents

Description

March 3, 1959 r A. STEYER 2,875,688

WEB CONTROL MEANS FOR ROTARY OFFSET WEB PRINTING PRESSES Filed Aug. 15, 1957 2 Sheets-Shet 1 b I INVENTOR ATTORNEYS A. STEYER 2,875,688 WEB CONTROL MEANS FOR ROTARY OFFSET WEB PRINTING PRESSES 2 Sheets-Shet 2 Filed Aug. 13, l957 m T N E V m ATTORNEY United States Patent WEB CONTROL MEANS FOR ROTARY OFFSET WEB PRINTING PRESSES Application August 13, 1957, Serial No. 677,899

3 Claims. or. 101-177 This invention relates to printing presses and more particularly to multiple unit web presses, and it has for its general object the provision of novel and improved means for maintaining control of the web between the units in order to insure register.

In the conventional arrangement of roll-fed ofiset perfecting web presses, for example, the web of paper is fed from the roll stand at one end of the installation, and proceeds through the press in a substantially straight line. At each printing unit, both sides. of the web are printed with one color. Each unit comprises two blanket cylinders, each having a plate cylinder running in contact therewith. Each blanket cylinder of a printing unit serves as an impression cylinder for the other blanket cylinder.

Now a blanket cylinder in presses of this type is provided with a gap (perhaps in the neighborhood of five eighths of an inch wide) in whichthe clamping mechanism for the ends of the blanket is located. The two cylinders of a given pair ars so timed that the gaps come into registry upon each revolution. This means that the web passing through the unit is not under the proper pressure between the cylinders at this moment and it is possible for the web to move or slip relatively to the printing couple and as a consequence it may be out of register with the impression at the next unit.

This condition is particularly noticeable in the case of cylinders of smaller diameters and in two unit presses and in presses of four or more units, in which only two units are being used for printing. In such cases the difficulty is aggravated and there is a definite tendency for double printing or mis-register.

The applicant has discovered that a very effective way of overcoming this lack of control of the web when the gaps come together is to cause the web to wrap slightly around at least one of the blanket cylinders instead of passing through the printing couple in absolute tangency with the cylinders. In this way the web is still in contact with the blanket portion of the cylinder through a slight are even though it spans the gaps.

The invention, therefore, in its preferred embodiment contemplates the provision of ingenious but simple and inexpensive means for efiecting this objective. One or more rollers (preferably two. as a most practical arrangement) are mounted for rotation between the adjacent printing units so that when the web is trained around them it is diverted either upwardly or downwardly out of its otherwise straight tangential path as it leaves the first printing couple. When two rollers are used the second one serves to bring the web back to its straight path whereby it enters the second unit tangentially to both cylinders.

Other preferred qualifications, but not however limiting in all cases, are the provision of grated surfaces on the auxiliary rollers so that only a series of points touch the web and offsetting of freshly printed ink is prevented or minimized, making the rollers the same diameter as the cylinders so that in practice any ink which might be 2,875,688 Patented Mar. 3, 9

ice

. "2' offset onto the points of the surface of the rollers would be transferred back to. succeeding portions of the web in register and would not appear in non-printed areas of the image or composition, and supporting the rollers in horizontal alignment with either the upper or lower blanket cylinders of the two units.

The auxiliary web guiding rollers are preferably idling rollers, but may be driven if desired.

Other objects and features of novelty will be apparent from the following specification when read in connection with the accompanying drawings in which one embodiment of the invention is illustrated by way of example.

In the drawings:

Figure 1 is a somewhat diagrammatic view in side elevation of a two unit offset web press according to the principles of the invention; and

Figure 2 is a fragmentary view on an enlarged scale showing in some detail how the web is constrained to follow the contour of the cylinder fora short distance beyond the conjunction of the two gaps in the blanket cylinders.

In Figure l of the drawings there is shown in quite diagrammatic form a web press of the offset perfecting type, and this illustration may represent a two-unit press or the two adjacent units of a four-unit press of the general type now in use. p

The press is designated generally by the reference numeral 10 and the first unit is shown at 11 and the second unit at 12. These printing units are supported and surrounded by the usual framework appurtenant to large presses of this type, which framework may be given the general designation 13. 1

The web roll is indicated at 15 and the axis shaft 16 of the roll is supported upon the framework 17 which also supports the set of preliminary feed rolls 18 through which the web 20 is fed toward the press proper.

The initial printing unit 11 includes an upper blanket cylinder 25 and a lower blanket cylinder 26, the upper cylinder 25 being supplied with an inked image of the text composition or other impression to be printed, by means of theplate cylinder 27, the lower blanket cylinder 26 being similarly impressed from 'the plate cylinder 28.

The second printing unit 12 is provided with an upper blanket cylinder 30, a lower blanketjcylinder 31 and plate cylinders 32 and 33 which apply the inked image to the respective blanket cylinders.

Although the present invention is particularly applicable to the offset perfecting presses ofv the type illustrated and described herein, it is of course not strictly limited thereto except in so far as indicated by the subjoined claims. However, since the invention satisfies a peculiar need in this type of press it has been illustrated in con nection therewith. In presses of this type it will be understood that the web 20 passes between the two blanket cylinders 25 and 26 and between the cylinders 30 and 31 and receives an impression upon both sides from the inked images on both of the blanket cylinders. In this case, of course, each blanket cylinder acts as an impression cylinder for the other one.

Referring now more particularly to Figure 2 of the drawings, it will beseen that the upper impression cylinders 25 and 30 are each provided with a bianket w, the respectiveopposite ends of which are clamped between pairs of bars as at 41. and 4-2, one of the sets of clamping bars being received within an indentation 43 in one wall of the recess 45..-formed in the structure of the cylinder 25, 30.

unit so that a portion of the web -bent around the cylinder (in this der 26, 31) and this will be sufficient to insure sufiicient provided with such surfaces.

to grip the clamped end structure 42 of the blanket 4t)- and apply tension" to the blanket to cause it to adhere snugly to the surface of the cylinder 25, 30.

It willbe readily seen that the blanket clamping de- -vices in these usual constructions leave a gap which is indicated at 60 where the end portions of the blanket 40 'leave the'cylindrical surface of the rolls 25, 30 and enter cylinders and the various parts are given the same reference numerals with the addition of a prime.

7 The fastening provisions for the blankets of the lower "cylinders26, 31 also leave a similar gap 60' which when the cylinders are set for proper operative registry, coincide once each revolution and provide a space, of more or less longitudinal extent, along the web where the web would be momentarily free of clamping support between the cylinders, and unless specific provisions are made, the web would be subject to displacement which would destroy the registry and cause double printing.

' Inorcler to prevent this eventuality and insure that the web is in firm rolling contact with one or the other of the blanket cylinders for an adequate arcuate extent to prevent any inadvertent slippage, means are provided for angling the course of the web 20 beyond the printing (say from the gap 60, 60', to approximately the point 61 shown in Figure 2) is case the lower cylinfrictional contact with the blanket to prevent displacement, such as would occur if the web were unsupported at the gaps 60 and 60'.

For accomplishing this, a pair of rollers 65 and 66 areinstalled upon the frame 13 preferably for free ro- '-tation between the printing units 11 and 12. Also, by

preference, the rollers 65 and 66 are of the same diameter as the blanket cylinders and are lined up with one or the other of the pairs of the upper and lower cylinders 25 and 30 or 26 and 31. In the illustrated embodiment they are aligned with the lower blanket cylinders 26 and 31. The web 20 is'trained around the lower periphery of the initial roller 65 and thence upwardly between the rollers which are spaced apart, for example as illustrated, and thence around the upper peripheries of the second roller from whence the web leads directly and tangentially between the bite of the blanket cylinders 30 and 31 of the second unit 12.

Preferably the surfaces of the rollers 65 and 66 are provided with prickly grater-like surfaces 70 formed with a multitude of minute points which serve to support the Web at spaced points of exceedingly small area and thus minimize greatly the amount of ink which might be transferred from the freshly printed surface of the web to the rollers. It is preferred that both rollers 65 and 66 be It will be noted also that by making the diameters of the rollers 65 and 66 the same as the diameters of the blanket cylinders, any transfer of ink from the impression offset onto the fine points of the surfaces 70 will be transferred back to the web in registry and will not appear in non-printed areas of the image.

Supplemental or auxiliary rollers of the same type may be installed beyond the second printing unit 12 for accomplishing the same purpose, as suggested at 65' and 66. For most purposes the auxiliary rollers are idler rollers, but means'for driving them may be provided whenever this is found desirable.

Quite obviously the same advantageous result may be obtained by lining up the auxiliary rollers 65 and 66 with the upper blanket cylinders 25 and 30, in which case the web 20 will be led from the bite of the cylinders 25 and 26 upwardly around the upper portion of the periphery of the initial rollers 65 and thence downwardly to pass around the underside of the roller 66 and thence through the bite of the blanket cylinders 30 and 31 of the second unit.

It is understood that various changes and modifications may be made in the embodiment illustrated and described herein without departing from the scope of the invention as defined by the following claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In an offset perfecting web printing press, in combination, at leastone printing unit which includes a pair of blanket cylinders, the common axial plane of said cylinders being approximately perpendicular to the direction of advance of the web through the press; plate cylinders supported in the press for rolling contact with the respective blanket cylinders for applying inked images thereto; means supporting said blanket cylinders for rolling contact with the respective opposite surfaces of a web passing between them, each blanket cylinder thus actingas an offset printing cylinder and also as an impression cylinder with respect to the other of said blanket cylinders; a gap in the periphery of each of said blanket cylinders as where the blanket ends securing means are disposed, the registry of the two directly cooperating blanket cylinders being such that the two gaps coincide upon opposite sides of the web at one point during each rotation, the web being thus momentarily out of gripping contact with the cylinders; an auxiliary roller supported in the press for rotation upon the delivery side of the printing unit, the printed web passing about said roller for at least a limited arcuate portion of its circu1nference, the point of tangency of the approaching web with respect to said auxiliary roller being displaced from and out of alignment with the common plane of tangency passing between the two blanket cylinders, which plane represents the conventional course of the web in such presses, whereby the web is constrained to pass around one of said blanket cylinders through a slight arc of contact with the blanket thereon instead of substantially upon a mere line of tangency, thus being always in contact with the blanket portion of at least one of the blanket cylinders; the diameter of the said auxiliary roller being of equal length to the diameter of said blanket cylinders so that any ink which might be offset 'onto the rollers will be transferred back to the web in register andwill not appear on non-printed areas of the impression image.

2. The web press as set forth in claim 1 in which said auxiliary roller is provided with a grater-like surface comprising a multiplicity of minute protruding points, whereby only the ends of said minute points contact the web and offsetting of ink onto the roller is minimized.

3. The web press as set forth in claim 2 in which there are provided two of said auxiliary rollers, the first one disposed and running in contact with said web as described and the other disposed close to but not in rolling relationship to the first one, and the web passing between the rollers and contacting them both for a limited arcuate extent, means supporting said other auxiliary roller so that the web may be fed off said other roller in the common plane of tangency of two similar blanket cylinders of a succeeding printing unit.

References Cited in the file of this patent UNITED STATES PATENTS

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