US3160094A

US3160094A - Method of rough registration for reprinting on a flexographic printing press

Info

Publication number: US3160094A
Application number: US274101A
Authority: US
Inventors: Lawrence H Bean
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-04-19
Filing date: 1963-04-19
Publication date: 1964-12-08
Anticipated expiration: 1981-12-08

Description

Dec. 8, 1964 1.. H. BEAN 3,160,094

METHOD OF ROUGH REGISTRATION FOR REPRINTING ON A FLEXOGRAPHIC PRINTING PRESS Filed April 19, 1965 3 Sheets-Sheet 1 STATION 2 STATwM 4 INVENTOR LAUJQEHCE H BEAM ATTORNEYS Dec. 8, 1964 3,160,094

L.H.BEAN METHOD OF ROUGH REGISTRATION FOR REPRINTING ON A FLEXOGRAPHIC PRINTING PRESS Filed April 19, 1963 5 Sheets-Sheet 2 INVENTOR LAwQEMcE' H; Beau OZ M ATTORNEYS Dec. 8, 1964 L. H. BEAN 3,160,094

METHOD OF ROUGH REGISTRATION FOR REPRINTING ON A FLEXOGRAPHIC PRINTING PRESS Filed April 19, 1963 3 Sheets-Sheet 5 INVENTOR LAWRENCE H BEAu ATTORNEYS United States Patent METHOD (ll RQUGH REQESTRATIGN FGR REPRHNTING @N A FLEXUGRAPHIC PRINT- DJG PRESS Lawrence H. Bean, 225 Mount Hope t., North Attlehoro, Mass. Filed Apr. 19, N63, Ser. No. 274,101 2 Claims. (tll. 101-481) This invention relates to flexographic multicolor printing, and more particularly to an improved method for rough registration of the colors at successive stations of a stack or drum type flexographic printing press at the beginning of each repeated use for a set of printing plate cylinders, as well as an improved plate cylinder which provides a preferred structure for carrying out the method.

In order to fully disclose the method involved, it is necessary to show and describe the basic structure of a typical flexographic printing press in some detail and to further show certain schematic views further clarifying the operation of such a press. It will be understood, therefore, that the press assembly is, in itself, not a part of my invention, my invention being in the method and in an improved structure, in the form of an improved plate I cylinder, for use on the press described.

form plastic bags for food products or the like.

The two most common types of presses used in such fiexographic printing are the stack type press, disclosed in FIGURES l and 2 of the drawings, and the drum type press, disclosedschematically in FIGURE 3 of the drawings. In the stack type press, there are multiple color stations with an impression cylinder for each station or for paired stations. In the drum type press, there are multiple color stations with a single impression cylinder which serves all of the stations. Both presses, however, are alike in that a running web moves successively from one station to the-other, a separate color being printed at each station. Each station involves a plate cylinder which carries one or more flexible rubber printing plates. The printing plates are suitably inked and print one color at each station, the plate or plates on a given cylinder printing only a portion of the total printed matter which appears on the finished web. When the web has passed all of the stations, it will present a clear, composite but unitary multicolor printed design, if the colors have been properly lined up or are in proper registration.

One of the main problems of the type of printing described, therefore, is the time consuming work necessary to register, or synchronize, the depositing of the ink from succeeding cylinders so that the ink is applied to the web in exactly the right position, which in the art is called color registration.

The presently known method of handling color registration in a given printing job is to remove the plate cylinders from the press and place them on a mounting or proofing machine. Longitudinal registration is handled on the mounting or proofing machine and is not difficult because the ends of the plate cylinder provide a fixed reference for measurements. Peripherfl registration, therefore, is the most difiicult problem. The plates are cemented to the cylinder in rough approximation according to the design involved, and the cylinders are then replaced in the press. The first down color is printed at the first station, and the second down color is then deposited over the first printing. The chances are that the printing at An example of the use for 3,lfi,% Patented Dec. 8, was

the second station is not in peripheral registration with the material printed at the first station. Consequently, the press is stopped, the plate cylinder at the second station is loosened and is then rotated an approximate distance necessary to bring the plate into registration with the color printed at the first station. This operation is repeated until an adequate rough registration is obtained, and then it is repeated for each succeeding station until total rough registration is accomplished. It will be obvious that this is a time consuming operation, requiring a large amount of down time for the press and further requiring considerable technical skill.

It may be pointed out that very fine adjustments can be and are made While the press is in actual operation. By suitable structure, usually in the form of spiral gears connecting the impression cylinder and plate cylinder of the press, the shaft of the plate cylinder may be rotated a very small extent. For example, in the known presses the limit of registration obtainable by fine registration is from one quarter inch to one half inch. This achieves hairline registration, but this final adjustment is inoperable unless the total rough registration is properly made.

It is important to note that most sets of printing plates are used, broken down, stored, and are then repeatedly employed for successive reprintings of the original design. Each time a reprinting is run through the press, therefore, it is necessary under present methods to go through the laborious, time consuming total rough registration. Because of the high cost of flexographic printing presses, it is necessary that the press be in operation the maximum possible time. It would be of major importance to the press operator if the time now required for rough registration could be reduced for each reprinting operation.

It is an object of the present invention, therefore, to provide a method of rough color registration for reprinting operations on flexographic printing machines requiring only a matter of minutes as compared with an hour or more of down time required under the presently known methods, an example in a typical operation involving a rough registration time of one and one-half minutes as compared with up to one and one-half hours.

Another object of the invention is to provide a method for rough registration for reprinting operations which may be carried out by relatively unskilled. help, it being necessary to use expensive, highly skilled help only for the initial development and first rough registration of a set of printing cylinders.

Still another object of the invention is to provide a method which is applicable to both stack and drum type printing presses and which is also equally applicable whether the plate cylinders are of the integral type or of the demountable sleeve type.

Another object of the invention is to provide an improved plate cylinder for flexographic printing presses which presents a preferred and simplified structure for carrying out the method of rough registration.

Still another object of the invention is to provide a preferred plate cylinder structure for use in carrying out the method which is simple but highly effective, which does not require any redesign of the printing presses now used, which is economical and wherein the plate cylinder may be of either the integral or the demountable sleeve type.

With the above and other objects in view, as will be presently apparent, the invention consists in general of certain novel details of construction and combinations of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly claimed.

In the drawings, like characters of reference indicate like parts in the several views, and

FIGURE 1 is a fragmentary side elevational view of a stack press which is used in carrying out the method of the invention and to which the improved plate cylinder devised as a preferred way of carrying out the method is applied;

FIGURE 2 is a schematic showing of a stack press similar to that of FIGURE 1,'whicl1 illustrates in a simplified manner the basic operation of the press;

FIGURE 3 is a schematic showing of a drum press, with which the present method and apparatus may be used; 7

FIGURE 4 is a fragmentary, isometric, exploded view showing my improved plate cylinder and illustrating the manner in which an angle gauge is applied for exact angular positioning of the cylinder;

FIGURE 5 is an end elevational view of the arbor of the printing plate cylinder of FIGURE 4, showing the angle gauge as it is positioned on the pins for establishing a precise angular position of the plate cylinder;

FIGURE 6 is a fragmentary, isometric, exploded view of a second form of my improved plate cylinder, wherein the cylinder is of the demountahle sleeve type, and showing the manner in which an angle gauge of modified structure is used to establish a precise angular position;

FIGURE 7 is a fragmentary, isometric view of a modification of the plate cylinder of FIGURE 4, wherein milled lugs are used in place of pins; and

FIGURE 8 is a fragmentary, isometric view of still another modification of the plate cylinder of FIGURE 4,

wherein a milled slot is used in place of the spaced pins.

Flexographic Priming Press The method and improved plate cylinder structure are used on a flexographic printing press. This press is in itself not a part of the present invention, but in order to fully disclose the method, it is necessary to show and describe enough of the press structure for a full understanding of the invention; In FIGURE 1, therefore, there has been shown in side elevation a stack type fiexographic printing press. FIGURE 2 is a schematic showing of a press similar to that of FIGURE 1, so as to more clearly illustrate the working of the stack press. FIGURE 3 is a schematic showing of a drum type press, with which the invention may equally well be used. In summary, the method and improved plate cylinder may be used with any press wherein a running web moves in succession to a plurality of printing stations, each station using a separate plate cylinder for printing a separate color forming part of a composite printing or design. It is evident, therefore, that while there has been shown for illustrative purposes a stack type press, any press presenting the basic printing relationship may be used.

In describing the press, only the parts which are critical to the invention and to a full understanding thereof will be set forth in detail.

In the press of FIGURE 1, there is provided a base frame 10 which supports spaced vertical rails Til. Iournalled for rotation on the vertical rails 11 are spaced

impression cylinders

12 and 13. For purposes ofeconomy, each impression cylinder serves two stations, although in the schematic of. FIGURE 2, there is a separate impression cylinder for each station, and the additional rolls are identified as He and 13a, respectively. These rolls are driven at a constant speed by drive means which need not be described in detail, except to note that a belt or chain 14 insuresthat both rolls are driven at a constant related speed. A supply roll lficarries the unprinted web W, which feeds over idler roller 15 and nip roller 17. The web passes through

stations

1, 2, 3 and 4, the mechanisms at each station being identical, and it is therefore necessary to describe in detail only the first station.

A movable frame 18 carries the plate cylinder 19, which will be described later in greater detail. At this point, it is only necessary to state that this cylinder has the flexible rubber printing plates fastened thereto, and the impression is created by the pressure between the impression cylinder 12 and the plate cylinder 19. An adjustment screw 2t provides a means for moving the frame 18 and controls repeated use of a set of printing cylinders.

4 the relative pressure of the rolls 12. and 19. The frame 18 carries the secondary slidable member 21 which is in the form of an ink tank carrying the inking roll 22 which revolves in the ink bath. A transfer roll 23 transfers the ink from the inking roll 22 to the plates on the plate cylinder 15. A second adjustment'screw 24 adjusts the pressure of the transfer roll 23 against the plate cylinder. Other adjustments are present which need not be described. fter it passes station 4, the web W passes over idler rollers 25 and Z6 and onto certain drying stations which need not be described;

In the drum type press of FIGURE 3, a single impression cylinder 12b serves all four plate cylinders, the structure and operation otherwise being the same as for the stack press of FIGURES 1 and 2.

At

Stations

2, 3 and 4, the plate cylinders are designated'as 19a, 19b and 190, respectively, repetition of the numbers of other elements at the stations not being necessary. It will be observed, therefore, that in passing from plate cylinder 19 to 1%, the web W travels a fixed distance. An impression is printed by the plate 27, and in order for the impression printed by the plate 27a to register with the impression printed by the plate 27, the angular position of the plate cylinder 19a about its longitudinal axis is quite critical. This is true in succession for

plate cylinders

19b and 1%, and it is the setting of this angular relationship which in the art is known as rough registration. pression cylinder and the plate cylinder 19 is held fixed by means of positive drive gears, not shown. Adjustment is made, therefore, by loosening the arbors 28 of the plate cylinders in their respective drive gears. When the arbors are so loosened, the plate cylinders may be rotated freely within bearings 29 to any desired angular position about their longitudinal axis. The ends 30 of the arbors project beyond the bearings 29 so that said ends are exposed.

It will thus be seen that rough registration for the first run and for all succeeding reprintings involved a trial and error settting of the angular position of the various plate cylinders about their axis. This is a time consuming procedure and resulted in substantial down time for the press.

Method of the Invention The invention is concerned, therefore, with a method of achieving rough registration at the beginning of each In the initial running of the set of cylinders, rough registration must be achieved by the usual long method, but thereafter the method of the invention may be used for setting up the press for a run in a fraction of the time previously required.

In setting up the initial printing run, a longitudinal prime line 31 is marked on each

plate cylinder

19, 19a, 19b and 19c, and the plate 27 is set exactly on the prime line. This insures that in repeated use of the plate, the plate will be installed in exactly the same position upon the plate cylinder 1%. A reference line is then established .on the end of each plate cylinder, which reference line is in a fixed position relative to the prime line 31. For the purpose of the method, this reference line may be a line 32 scribed on the end 3% of the arbor 23. This line may be in any fixed position relative to the prime line 31 as long as the relative positions are exactly the same for each of the plate cylinders. Preferably, as shown in FIGURES 4 and 6, the reference line is at an angle of '90 degrees relative to a plane taken through the prime line and the axis of rotation of the plate cylinder.

When each plate 27 has been mounted, therefore, initial rough registration is accomplished by the trial and error method and then fine registration is preferably accomplished until registration is as near perfect as possible. At that point, the angular relationship of each plate cylinder is measured relative to a gravitational The rotative relationship between the imhorizontal, using the reference line as a base. Any suitable bubble or pendulum type gauge 33 may be used, as long as the angular position of the reference line may be measured in terms of degrees with fairly close accuracy. An indicator mark, such as the mark 34, must then be made to indicate on which side of the reference line 32 the angle is measured. An angle is then recorded for each

plate cylinder

19, 19a, 19b and 19c, and kept as a permanent record.

The set of plates for a particular job may then be broken down from the plate cylinders and stored with the permanent records of peripheral and axial rough registration. When the job is to be reprinted, the plates 27 may be withdrawn from the files, and each plate is set exactly on a prime line of the plate cylinder. The cylinder is then mounted in the hearings in its proper station. The plate cylinder 19 is then revolved by hand until the reference line 32 is at its proper recorded angle according to the applied gauge 33. The said plate cylinder is then held in this position by tightening the drive gear on arbor 28. This is done in succession for each of the succeeding

plate cylinders

19a, 19b and 196. The cylinders are then in very good rough registration for running the job and can be quickly put into very fine registration by the well known fine registration adjustment means previously mentioned. When the plates 27 have been adhered to the plate cylinder at their prime line location, then a typical time on a typical four station job to mount the plate cylinders and achieve good rough registration is in the order of one and one-half minutes. The same rough registration for a reprinting, Without using the method of the present invention, would take a highly skilled man from twenty minutes to one and one-half hours.

Improved Plate Cylinder As a part of the invention and in order to better carry out the method, there has been developed an improved plate cylinder. In the preferred form shown in FIG- URES 4 and 5, the cylinder is provided with a prime line groove 31. In fixed relationship to the groove 31 and on a line passing through the axial center of the end 30 of the arbor 28 are placed the spaced pins 35. These pins provide a reference line surface upon which the gauge 33 may be placed for accurate measurement of the angle of a plate cylinder relative to a gravitational horizontal.

It is not necessary that the reference line surface be formed by spaced pins. In the alternate form of FIG- URE 7, spaced lugs 36 may be used. In still another alternate form, shown in FIGURE 8, a milled slot 37 may be used. The possible inversion of the slot 37 would be an end rib.

In one form of plate cylinder well known in the art, the arbors 28 are made separate from the plate cylinder, and the arbors are removably fitted to the cylinder 19. In this case, the reference surface cannot be placed at the end of the arbor, as in the forms of FIGURES 4, 7 and 8. Therefore, the reference line surface is formed by the drilling of two holes 28 in the end of the plate cylinder 19 itself. These holes are on a diameter of the end of the plate cylinder. For angular measurement, a special yoke 39 is attached to the angle gauge 33. The yoke is provided with spaced pins 40, which fit into the holes 38. This provides the desired reference surface for the plate cylinder. Preferably, the pins 40 are slightly tapered and are of softer material than the material of the plate cylinder. The holes could be on an insert that could be removed and replaced in the event of wear of the holes.

While there has been shown and described herein the preferred form of the invention, it is nevertheless to be understood that minor changes may be made therein with out departing from the spirit and scope of the invention as claimed.

What is claimed is:

1. A method of rough registration of a set of printing cylinders for repeated runs on a multicolor, multistation, continuous web printing press having separate plate cylinders for each station which are capable of being released for free rotation in their bearings, comprising (a) marking a longitudinal prime line on each of said plate cylinders,

(1)) making an initial mounting of the plates on successive plate cylinders in a fixed, standard position relative to said prime line,

(0) establishing a reference line on an end surface of each of said plate cylinders,

(d) bringing said plates by a trial and error method into an initial peripheral registration at each station by free rotation of each plate cylinder about its longitudinal axis,

(e) measuring the angle of said reference line of each of said plate cylinders relative to a gravitational horizontal and recording said angle for each station,

(f) remounting said plates on said plate cylinders at the time of a reprinting in the same fixed position relative to said prime line as in the initial mounting, and

(g) rotating freely each of said plate cylinders until the reference line on said cylinder is at the angular position relative to said gravitational horizontal previously recorded for the particular station thereby achieving immediate total rough registration of the set of printing plates.

2. A method of rough registration of a set of printing cylinders for repeated runs on a multicolor, multistation, continuous web printing press having separate plate cylinders for each station which are capable of being released for free rotation in their drive bearings, comprising (a) marking a longitudinal prime line on each of said plate cylinders,

(b) making an initial mounting of the plates on successive plate cylinders in a fixed, standard position relative to said prime line,

(c) establishing a reference line on an end surface of each of said plate cylinders, the relationship of the prime line to the reference line being exactly the same for each of said plate cylinders,

(e) measm ing the angle of said reference line of each of said plate cylinders relative to a gravitational horizontal and recording said angle for each station,

(1) remounting said plates on said plate cylinders at the time of a reprinting in' the same fixed position relative to said prime line as in the initial mounting, and

(g) rotating freely each of said plate cylinders until the reference line on said cylinder is at the angular position relative to said gravitational horizontal previously recorded for the particular station, thereby achieving immediate total rough registration of the set of printing plates.

References Cited by the Examiner UNITED STATES PATENTS 572,276 2/97 Osborne 101-248 X 896,899 8/08 Dietrich 101-178 1,083,543 1/14 Kroenert et a1. 101-178 1,931,730 10/33 Klay 33-207 X 2,172,279 9/39 Hamilton 101-248 X 2,231,187 2/41 Hawley 101-211 X 2,348,095 5/44 Roby 33-207 X 2,531,799 11/50 Zumwalt 33-207 X 2,559,533 7/51 Daniels. 2,894,454 7/59 Hillier 101-211 EUGENE R. CAPOZIO, Primary Examiner.

Claims

1. A METHOD OF ROUGH REGISTRATION OF A SET OF PRINTING CYLINDERS FOR REPEATED RUNS ON A MULTICOLOR, MULTISTATION, CONTINUOUS WEB PRINTING PRESS HAVING SEPARATE PLATE CYLINDERS FOR EACH STATION WHICH ARE CAPABLE OF BEIG RELEASED FOR FREE ROTATION IN THEIR BEARINGS, COMPRISING (A) MARKING A LONGITUDINAL PRIME LINE ON EACH OF SAID PLATE CYLINDERS, (B) MAKING AN INITIAL MOUNTING OF THE PLATES ON SUCCESSIVE PLATE CYLINDERS IN A FIXED, STANDARD POSITION RELATIVE TO SAID PRIME LINE, (C) ESTABLISHING A REFERENCE LINE ON AN END SURFACE OF EACH OF SAID PLATE CYLINDERS, (D) BRINGING SAID PLATES BY A TRIAL AND ERROR METHOD INTO AN INITIAL PERIPHERAL REGISTRATION AT EACH STATION BY FREE ROTATION OF EACH PLATE CYLINDER ABOUT ITS LONGITUDINAL AXIS, (E) MEASURING THE ANGLE OF SAID REFERENCE LINE OF EACH OF SAID PLATE CYLINDERS RELATIVE TO A GRAVITATIONAL HORIZONTAL AND RECORDING SAID ANGLE FOR EACH STATION, (F) REMOUNTING SAID PLATES ON SAID PLATE CYLINDERS AT THE TIME OF A REPRINTING IN THE SAME FIXED POSITION RELATIVE TO SAID PRIME LINE AS THE INITIAL MOUNTING, AND (G) ROTATING LFREELY EACH OF SAID PLATE CYLINDERS UNTIL THE REFERENCE LINE ON SAID CYLINDER IS AT THE ANGULAR POSITION RELATIVE TO SAID GRAVITATIONAL HORIZONTAL PREVIOUSLY RECORDED FOR THE PARTICULAR STATION THEREBY ACHIEVING IMMEDIATE TOTAL ROUGH REGISTRATION OF THE SET OF PRINTING PLATES.