GB2092069A - Web lithographic press row identifier - Google Patents

Abstract

An improved printing couple for a multi-row web-offset lithographic press which includes a plate cylinder is with diametrically opposed lockup gaps 16, a cooperating blanket cylinder having a single lockup gap, and a separate printing means 30 mounted within the plate lockup gap 16 corresponding to the non-gap lockup area of the blanket cylinder for printing a character on the travelling web that identifies which press row printed the product being examined. <IMAGE>

Description

SPECIFICATION Web lithographic page/plate marker Background of the Invention The production of much web lithographic printed matter is accomplished at press installations where large numbers of printing couples are utilized in multi press rows or lines. For example, the web-offset production of newspaper or newspaper-like publications is commonly effected on press installations comprised of from one to ten or more press rows or lines. The webs that are printed at the individual press rows are ultimately cut, assembled and folded to form individual copies.

Most large newspaper production facilities, due to the large number of newspapers being printed for one or more editions, will print the same product at the same time on two or more press rows or lines. Management and or quality control evaluates the printed products for various types of errors in platemaking, advertising and pressmanship. Since the same product is printed on all press rows, some means of identification has to exist to determine which press row a given product was printed on, thus allowing for corrections when errors are found. The identification is more or less fixed and seldom, if ever, changed from day to day. Currently, web letterpresses have a device for such identification; however, on lithographic printing presses, no such device has been invented due to the nature of the narrow gap required in the plate and blanket cylinders.

It is a principal object of this invention to provide means to be used in conjunction with the printing press rows or couples of a webfed rotary press that identifies the press row on which the travelling web is being printed.

An additional object of this invention is to provide an auxiliary printing element that is secured to the plate roll.

Other objects and advantages of this invention will be in part obvious and in part explained by reference to the accompanying specification and drawings in which: Brief Description of the Drawings Figure 1 is a schematic showing the manner in which the inking rolls, plate roll and blanket cylinder interact in a lithographic printing couple; Figure 2 is an enlarged end elevation showing the manner in which the supplemental printing means of the invention is mounted in the plate roll; Figure 3 is a side elevation showing the supplemental printing means mounted in the plate cylinder lockup gap; and Figure 4 is a top elevation showing the supplemental printing means in the plate cylinder lockup gap.

Description of the Preferred Embodiment To more fully understand the present invention, reference is made to the accompanying drawings and the following description. In lithographic printing, or specifically in web off-set lithographic printing with which this invention is concerned primarily, printing is accomplished by means of flexible litho plates that are photographically exposed and etched before being mounted on the plate cylinder of the press. Litho plates are basically considered to be non-relief printing since no portion of the surface of the plate is greatly elevated above any other part. Printing is accomplished through the photographic and etching procedures so that the areas of the plate that are to receive ink to effect printing are oilophilic whereas the remainder ot the plate is hydrophilic.Thus, when water and dampening fluid (primarily water) are applied to the surface of a litho plate, certain areas attract the oil-based ink while other areas attract dampening fluid.

In off-set lithography, the ink that has been applied to the plate roll is transferred to a blanket roll which in turn conveys the transferred ink to a web of travelling newsprint. A plate roll normally carries a plurality of pairs of cylinder flexible plates, each plate of which extends around approximately 180 of the surface of the plate roll and is secured at each end to the plate roll in a plate cylinder lockup gap. Thus, each plate roll has a pair of diametrically opposed lockup gaps to receive the ends of each pair of litho plates and the plate lockup mechanism.The blanket roll carries on its outer surface a plurality of layers of cushioning and ink receiving material which layers extend completely around the outer surface of the blanket cylinder and are secured within the single lockup gap that is manufactured into the surface of the blanket cylinder.

Referring to Fig. 1, there is shown schematically a printing couple such as that which would be used in printing a travelling web by means of off-set lithography. Specifically, Numeral 10 indicates an ink rail holding a quantity of ink 11 and having an ink roll 1 2 which removes the ink 11 from rail 10 for delivery into ink chain 1 3. Ink chain 1 3 which comprises a plurality of interconnected rollers, distributes the viscous ink evenly over the rolls and at the same time works it into a less viscous condition for delivery to the ink form rollers 1 4. ink form rollers 1 4 then transfer the ink to the periphery of the plate roll 1 5.

As can be seen in Fig. 1, plate roll 15 is formed with a pair of diametrically opposed lockup gaps 1 6 which are present to receive the ends of the flexible lithoplates 1 7 (see Fig.

2). Although not shown in the drawings, the printing couple would normally have a system for applying dampening fluid to plate roll 15 prior to the time that ink is supplied to roll 15 by ink form rolls 14. A variety of methods for applying water to plate rolls are well known and need not be described in detail in this text.

As the plate roll 1 5 rotates in the direction indicated by the arrow 18, it comes into contact with a blanket roll 20 which is rotating in the opposite direction 21 from the direction 1 8 of plate roll 1 5. Rotation of rolls 1 5 and 20 in contact with each other transfers ink and water from plate roll 1 5 to the surface of the blanket roll 20 which in turn delivers the ink and water to one surface of travelling web 22. The dotted lines indicated by numeral 23 in Fig. 1 indicate the blanket roll which would be present in presses where printing on both surfaces of travelling web is being executed simultaneously. In this case, an ink supply system and a dampening fluid supply system identical to that described above would be present.

It was earlier mentioned that the production of printed material wherein a large number of press rows were involved make it difficult for management and or quality control to ascertain quickly which press row requires adjustments and is not performing optimally or has errors. To eliminate this problem, the present invention provides a combination with the plate roll of a separate printing means, that is apart from the litho plates, which will print a distinctive indicium or indicia on the travelling web so that the printing press row can be easily and readily identified. Each press row would have a different indicium or indicia and within each such row, the idenfitying character could be more or less fixed.

Referring to Fig. 2, the plate cylinder 1 5 has the litho plates 1 7 secured on its outer periphery by means of the spring biased lockup elements 25. The lockup elements shown here are shown only by way of example since many other acceptable ways of securing litho plates on plate rolls are well known in the trade. Within plate lockup gap 16, there is located a separate printing means indicated generally by the numeral 30. This means comprises an elongated body portion 31 which is seated on top of a base element 32.

Both body 31 and base 32 are secured within lockup gap 1 6 by fastener means 33, here shown as being threaded fasteners which are received into threaded recesses 34 in plate roll 15.

Extending upwardly beyond the upper or outer surface of body portion 31 is the printing extension 35 that terminates in an outer surface 36 having both hydrophilic and oilophilic properties.

As shown in Fig. 4, this surface 36 could consist of hydrophilic and oilophilic areas and identified by numeral 37 (oilophilic) with the rest of surface 38 being hydrophilic so that the ink is not attracted to it. The number 3 (indicia) in Fig. 4 is only used for description; the indicia could be a number, alpha character or any geometric shape or design. The separate printing means 30 is constructed with a body portion 31 and base portion 32 so that means such as shim 40 can be inserted to alter the vertical position of the outer surface 36 so that it is located radially outwardly from the center of plate roll 15, the same distance as the printing surface of litho plate 1 7.

When the separate printing means of this invention is assembled into a plate roll, it will be placed in the plate lockup gap that correspond to the non-gap area of the blanket cylinder 20. This arangement is necessary in order that the surface 36 can transfer ink and water to the surface of the blanket cylinder for ultimate deposition on the traveling web 22.

Normally, it would be desired that printing means 30 be located adjacent one edge or the other of the plate roll so that the additional indicia will be printed near one corner or the other of the travelling web.

Although the present invention has been described in connection with a preferred embodiment, it should be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview of the scope of the appended claims.

Claims (5)

1. In combination with the plate roll of a web fed printing couple including a blanket cylinder having a single lockup gap and a plate roll having a pair of diametrically opposed plate lockup gaps, printing means separate from the printing plates on the plate roll for printing indicia on the travelling web to identify the printing couple or press row on which the web is being printed.

2. The combination as defined in Claim 1 wherein said separate printing means is secured within the plate lockup gap that corresponds to the non-gap area of the blanket cylinder.

3. The combination as defined in Claim 2 wherein said separate printing means comprises an upper surface having hydrophilic and oilophilic properties, an elongated body portion and fastener means extending through the body portion into the plate roll to secure the separate printing means thereto.

4. The combination as defined in Claim 3 wherein means are provided between said body portion and the base of the gap in the plate roll to alter the vertical position of the outer surface of said separate printing means with respect to the printing surfaces of the plates.

5. Rotary web-offset printing apparatus substantially as hereinbefore described with reference to and as shown in the accompanying drawings.