FR2553032A1 - FLEXOGRAPHIC PRINTING PRESS WITH DIRECT TAPPING AND PACKAGING MATERIAL THUS PRINTED - Google Patents

Abstract

THE INVENTION RELATES TO A ROTARY PRINTING PRESS FOR MULTI-COLORED USE ENSURING THE CORRESPONDENCE OF THE PRINTED MATERIAL BETWEEN THE PLATE CYLINDER AND THE PRINTING CYLINDER. ACCORDING TO THE INVENTION, A MICROPROCESSOR CONTROL UNIT 20 OF SEPARATE MOTORS 9 AND 6 DRIVING THE PLATE CYLINDER 2 AND THE PRINTING CYLINDER 1 MAINTAINS THE CORRESPONDENCE OF THE PRINTED MATERIAL DURING THE OPERATION OF THE PRESS; THIS ALLOWS THE PLATE CYLINDERS TO BE QUICKLY PRINTED BECAUSE THE CONTROL UNIT 20 MAINTAINS THE MATCH DESPITE THE SEPARATION OF CYLINDER 2 AND PRINTING CYLINDER 1, AND ALSO ALLOWS EACH OF THE VARIOUS PLATE CYLINDERS 2 OF A MULTICOLORED PRESS TO BE PRINTED SIMULTANEOUSLY WHEN APPROPRIATE MEANS OF MOVING THE PLATE CYLINDERS 14, 16 ARE PROVIDED. THE INVENTION APPLIES IN PARTICULAR TO THE PRINTING OF PACKAGING MATERIALS.

Description

The present invention relates to a rotary printing press, and

more particularly to the

  correspondence of the rolls of such a press.

  We know that a printing press will only give good results if there is a precise correspondence of the positions of the main cylinder or the

  printing plate and the middle on which one prints.

  In various types of printing presses, there are other components which must also be kept in exact correspondence with the main printing cylinder, for example the blanket in a press

rotary printing.

  Until now, a rotary printing press required precise gears to maintain cylinder matching after it had been established, and there was also a limit on the accuracy of the correspondence of the material. printed because the incremental minimum matching change is related to the pitch of the gears between the support of the main printing cylinder, normally the plate cylinder, and the medium of the printed medium, normally a printing cylinder. this situation relates to the fact that the thickness of the printing plate and / or any backing sheet or "setting-up" applied to the cylinder of the plate below the plate must be precisely controlled because of the inability to compensate for small variations in radial space between the surface of the

  plate and the axis of rotation of its cylinder to a degree of precision more accurate than a pitch of the teeth of the gears.

  Until now, the task of setting up a printing plate for accurate print matching has required the precise establishment of this radial space of the plate surface relative to its cylinder, so that the superficial velocities of the printing plate and the printing medium carried on the printing cylinder may be correct for a

  maintained correspondence of the printed matter.

  For effective printing, it is necessary not only that some of the running surfaces always come into contact with each other by the same parts, but also that the contact between all the running surfaces is a contact

pure rolling "friction free".

  Accordingly, according to one aspect of the invention, there is provided a rotary printing press which comprises a plate cylinder and a rotatable carrier of a printing material, a first motor driving said plate cylinder and a second driving motor. said medium of the printing material and a control means ensuring precise control of the mutual rotational positions of said first and second motors to ensure synchronization of the position of a plate on said cylinder with respect to said rotary support without requiring interconnection 20 between the cylinder of the plate and the support. The problems mentioned above are much more acute when the printing press is a multicolored press and it is necessary to have a very precise correspondence of the various plate cylinders, each bearing a different color, compared to

  the image printed by the other plates.

  According to a second aspect of the invention, there is provided a rotary printing press comprising a rotary support of the printing material, a plate cylinder adapted to support a plate on a portion of its cylindrical surface for rolling contact with an image transfer grip, a first motor driving said plate cylinder, a second motor driving said rotary support, and control means for controlling the position of said plate cylinder with respect to said rotatable support, said control means being effective to maintain the positional relationship at a constant superficial velocity of said plate cylinder to a first sector of rotation of the plate cylinder, and to vary the speed of said plate cylinder on a second sector of rotation of said cylinder to change the delay between the end of the first sector of a turn of the plate cylinder and the beginning of said first sector

  in the next successive turn of the plate cylinder.

  The invention will be better understood, and other purposes, features, details and advantages thereof will become more apparent in the course of

  explanatory description which will follow made with reference to the accompanying schematic drawings given solely by way of example illustrating several modes of

  Embodiment of the invention, and in which: FIG. 1 is a schematic perspective view of an inking unit and a set of plate rolls of a multicolour press whose printing cylinder is also illustrated; in the drawing, the press being according to the present invention; Figure 2 is a side elevational view showing a detail of the printing cylinder and the adjacent plate cylinder, and illustrating another embodiment of the present invention; and FIG. 3 is a diagram of the peripheral speed of the printing plate with respect to the angular position of the plate, and it applies to

  embodiment of Figure 2.

  Referring now to FIG. 1, there can be seen a printing cylinder 1 carrying a continuous web of a material to be printed, for example a continuous web of packaging plastic (not shown). The continuous strip of plastic material must be printed in at least two colors and the drawing shows the plate cylinder 2 carrying a plate 3 applicable for one of these colors. The drawing also shows the inking roll 4, preferably a roll in anilox "that applies ink to the

plate 3.

  In a conventional printing press, the plate cylinder will be mechanically connected by gears to the main shaft of the printing cylinder (rotatable about the axis of rotation 5a in FIG. 1) and the inking roller 4 in "anilox" will in turn be mechanically connected by gears to the plate cylinder 2 for frictionless contact between the finely profiled "anilox" roll 4 and the flexographic printing elastic plate 3 The arrangement is such that the roll 2 can be removed from contact with the printing cylinder 1 in order to interchange the plate cylinders or otherwise have access to the press components and the inking roller 4 and "anilox" is in turn separable from the cylinder 2, by For example, in order to stop the supply of ink to the plate 3 during operation or during the process of changing the plate while the machine is being adjusted for printing. This separability of the plate cylinder 2 and the cylinder indre printing as well as the inking roller 4 with respect to the plate cylinder

  2, is still possible with the present invention.

  However, instead of the usual gears between the printing cylinder 1, on the one handand the ink roller 4, on the other hand, three separate motors are provided in the rotary press according to the invention.

  controlled drives to be coupled to the respective rotary components.

  Thus, the impression cylinder 1 is rotated by its electric drive motor 6 which can come into motor engagement with a toothed pulley 7 on the drive shaft 5 of the printing cylinder by a toothed belt 8. In this case, the plate cylinder 2 is driven directly by its own numerically controlled electric motor 9 at the end of the drive shaft 10 of the plate cylinder, and likewise the inking roller 4 is driven by its

  own electric motor 11 with numerical control on the drive shaft 12 of the inking roller.

  In order to allow easy removal and replacement of the plate cylinder 2 and the inking roller 4, in this case quick-release mechanical couplings 13 are provided on the drive shafts 10 and 12 along

drive motors 9 and 11.

  At each end of the drive shaft 11 of the plate cylinder is a respective carrier 14 which is driven towards and away from the axis of rotation 5a of the impression cylinder 1 by means of a lead screw. 15 rotated

by a stepping motor 16.

  Similarly, at each end of the drive shaft 12 of the inking roller is a respective support 17 driven towards and away from the axis of rotation of the shaft 10 of the cylinder.

  plate by means of a lead screw 18 driven by a stepping motor 19.

  The improvement according to the present invention requires a main controller, in this case schematically illustrated by the control unit 20, to control the speed of rotation and the rotational position of the motors 9 and 11 with respect to the speed of rotation and the rotational position of the printing cylinder 1 (in this case, referring to the angular position and the speed of its drive motor 6) The control unit 20 also controls the operation of the stepper motors 16 and 19 cover "The control connections between the unit 20 and the various motors 6, 9, 11, 16 and 19

  are diagrammatically illustrated at 21 in FIG.

  Each of the motors 6, 9 and 11 is associated with an encoder or "position separator" which gives an accurate indication of the rotational position of the motor shaft and which generates pulses to be applied to the control unit. to enable this unit 20 to accurately match the mutual positioning of the printing cylinder 1, the plate cylinder 2 and the inking roll 4 in "anilox". A reaction of the position of the cover carriers 14 of the plate cylinder 2 and the supports 17 of the inking roller 4 is carried out by means of a proximity detection system 22 of the support 14 and another proximity detection system 23 of the support 17 The proximity sensor 23 of the support 17 detects the moment when the support 17 comes close to the erected portion of the support 14, and the proximity sensor 22 of the support detects the moment when the support 14 arrives close to a upright portion (not shown) of the

frame 24 of the machine.

  The control unit 20 preferably comprises a microprocessor for establishing and maintaining the positions of three motors 6, 9 and 11 with precision, and also allowing a variation of the rotational positional relationship in response to commands. ,

  applied by the operator, "print material advance" or "printed material delay".

  The microprocessor also makes it possible to separately actuate the "cover" stepper motors 16 and 19 for the "cover" movement of

  plate cylinder defined by the supports 14 and the platen of the inking roller defined by the supports 17.

  Such control systems responding to the position

  and now are well known and as the detailed circuit is not part of the present invention, we will draw attention to the descriptions of U.S. Patent Nos. 4,090,116 of May 16, 1978 in the name of

  DL Lippitt, No. 4 099 107 of July 4, 1978 in the name of J Eder, No. 4,344,127 of August 10, 1982 to GH Mc Daniel et al. And No. 4,357,561 of November 2, 1982 to the name of VR Fenci as examples of disclosures using a similar circuit to control with

  precision the position of moving elements.

  Reference may also be made, for more information, to US Pat. No. 4,377,847 of March 22, 1983 to RA Daniel et al., No. 4,277,191 of July 7, 1981 in the name of GW Davis et al., And No. 4,114,750. September 19, 1978 on behalf of HS Baeck et al. showing the use of an electronic order of

  position in printing systems.

  The surprising feature of the present invention is that it is possible to obtain and maintain precise positioning of the rotary components of the press, in this case the printing cylinder 1, the plate cylinder 2 and the means for applying the ink represented by the inking roller 4 in "anilox", simply by using an electronic control unit for the motors 6, 9 and 11 driving these various rotary components The price of conventional gears of a sufficiently high quality high to withstand rapid wear during the use of the press as well as the loss of time necessary to establish a precise match of the cylinder 2 with respect to the impression cylinder 1 while the plate cylinder is returned to the printing, and possibly to change the transmission ratio when a plate cylinder having a different radial dimension is installed, are saved by the control unit 20 and the doubled drive motors 9 and 11 for the

cylinder 2 and the inking roller 4.

  By virtue of the precise synchronization of the position of the plate cylinder 2 and the inking roller 4 with respect to the impression cylinder 1, it is possible, after removal of the cylinder 2 from its printing position, to restore this plate cylinder on printing without requiring a match of the printed material because the necessary correspondence is maintained under the control unit 20, and to know that a frictionless rolling contact of the ink-carrying ink-roller 4 and finely profiled in "anilox" with the plate

  flexographic printing in elastomer 3 on the 20 cylinder of the plate is guaranteed.

  The use of separate step motors 16 and 19, controlled by the unit 20, to cover the inking roller 4 and the plate cylinder 2 means that it is possible for the control unit to signal simultaneous coverage. of all inking units and all plate cylinders of a multi-color printing press with respect to the common printing cylinder 1 so that all the colors are able to print simultaneously This considerably reduces the time taken by the cover operation in comparison to a manual cover requiring the operator to place each plate cylinder carefully at the correct space with respect to the rotation axis 5a of the printing cylinder and correct angular alignment (in matching the gear teeth of a conventional press). Furthermore, it is well within the capabilities of the designer of the control unit 20 to allow an operation match of the printed material so that it is possible to return each of the plate cylinders in engagement with the medium that is printed. , substantially simultaneously covering all the colors, to subsequently adjust the positions of the individual plate rolls 2 to establish a precise match to ensure frictionless rolling contact of the inking roll 4 with the plate 3 during any adjustment of the correspondence of the material printed in operation, the control unit 20 will be able to change the rotational position of the ink cylinder in response to changes in position of the plate cylinder (proportionally to the diameters

  of the inking roller 4 and the plate cylinder 2).

  Correspondence of the printed material can also be ensured by adjusting rolls 1 and 2 by hand while they are stationary and (if necessary) adjusting the control unit 20 before restarting the press, for ensure that when the rotation of cylinders 1 and 2 resumes, the mutual rotational positions of cylinders 1 and 2 will

  pure rolling contact at their peripheries with correct correspondence of the printed material.

  The system according to the present invention presents

  another advantage which lies in the fact that the previous limit of the very small incremental change of the repeat length correspondence no longer exists.

  Whereas beforehand, the mechanical stresses of the tooth pitch of the gears prevented accurate adjustment of the repeat lengths (to allow the printing plate to be used over a larger diameter and consequently over a larger circumference) provided that the number of pulses produced per revolution of each of the motors 6, 9 and 11 is sufficiently high, there is a virtually indefinitely variable possibility of the adjustment necessitating a simple change in the multiplication ratio of the relationship of the motors. pulses of the various motors, by the operator applying an appropriate input signal

the control unit 20.

  The precise adjustment of the printed material is also facilitated because, while the precise adjustment (to any accuracy of less than one step of the teeth) previously included axial repositioning of the helical gears driving the plate cylinder, it It is now possible to make such an adjustment simply by temporarily changing the speed of the platen roller to relocate it relative to the platen roller.

the required increment.

  Other advantages of the system according to the invention reside in the fact that (a) the replacement of a plate cylinder is much more rapid because beforehand the plate cylinder had to be fixed to the common gear to all available plate cylinders of a given size and was attached (to the fixed plate cylinder) before the plate cylinder was installed in the press; (b) the time taken to clean the machine (eg for ink color changes) will be shorter because it is no longer necessary to clean the gears and ensure gear matching when the plate cylinder is reduced to printing; (c) the serious problem of guards on gears is eliminated; (d) the change in the thicknesses of the printing plate and backing sheet on the plate cylinder is more direct because the resulting small diameter variations of the plate / plate cylinder assembly can be corrected thanks to the much more precise adjustment of the report

255303 Z

  speeds which is made possible by the electronic control unit 20; and (e) the presence of "vibration or knock marks" in the printed material at the resonance of the gears, and also the general level of vibration in the press are reduced. Eliminating this vibration of the gears will further reduce the wear of the gears. Bearings and also the wear of the other associated components of the machine performing the positioning and movement of plate cylinders and / or inking rollers. The much more precise adjustment possibility allows the operator to compensate for very small changes in the cylinder diameter of the plate, for example after repolishing a plate cylinder, thus the service life of any cylinder.

  given can be considerably extended by use with the press according to the present invention.

  Figure 2 shows the possibility of optional optional arrangement in the press of Figure 1, provided that the control unit 20 is of the appropriate type.

  It has been assumed, everywhere in the description

  above, that the rotational speed of the platen roller 1 would be substantially uniform throughout each cycle, depending on the ability of the control unit 20 to maintain and / or restore the match by small changes in the speed of rotation. rotation of

cylinder 2 and the inking roller 4.

  With the optional feature illustrated in FIG. 2, the positional relationship of the platen roller 2 to the platen roller 1 must be simply maintained during the rolling of an AB sector of the platen roller beyond the right-of-way. During this rolling action, there will be above all a contact of a first plate or a first plate surface 3a to print a main shape on the medium to be printed, and then there will be a space corresponding to the sector. BA before a subsidiary plate or plate surface 3b prints a small panel at the end of the middle that is printed (eg a "registered trademark" sign at the bottom of a bag or an optical film match mark for subsequent detection by a photoelectric transducer, if the medium

  printed is a continuous strip of a plastic packaging material, such as a plastic packaging bag chain).

  While the printing of the main panel by the plate or plate surface 3a and the printing of the subsidiary panel by the subsidiary plate or plate surface 3b take place, there must be a precise correspondence of the position of the cylinder to plate 2 with the medium that is printed, and of course in the case of a multicolored press, there must be a precise match of the other cylinders in use with the medium that is printed However, while the BA sector is rolling Beyond the printing footprint, no printing is performed and the absence of a relief printing plate region on this sector BA makes it possible to vary, as desired, the speed of printing.

plate cylinder 2.

  This possibility of varying the speed is particularly useful because it makes it possible to vary the repetition length (that is, the space on the material printed between two successive images of any part of the plate or part 3 or 3b, and therefore the space between the main panel printed by the plate or plate portion 3a and the subsidiary panel printed by the plate or plate portion 3b), or by increasing the speed of the rotation of the plate cylinder 2 on the BA mains to reduce the repetition length or by reducing the rotation speed of the plate cylinder on the BA sector in order to increase the repetition length The rotation speeds must, however, be precisely synchronized when the

sector AB is in the grip.

  The possibility of optional variation of the repetition length illustrated in Fig. 2 therefore necessitates that the control unit 20 is able to maintain accurate positional synchronization of the plate cylinder 2 during the rolling of the AB sector (called the constant velocity sector ") beyond the printing footprint and allows an increase or decrease in the rotational speed of the plate cylinder 2 while the sector BA (hereinafter referred to as" variable speed sector "). ) rolls past the print right-of-way, with restoration of accurate position matching at the end of the variable speed sector so that the subsidiary panel can

  be properly printed on the packaging material.

  FIG. 3 shows the possibilities of variation of the repetition length in order to obtain the desired results. The curve 31 shows a very short repetition length, the curve 32 shows a somewhat longer repetition length, the curve 33 shows a length of repetition even longer and the curve 34 shows the most important of the four repetition lengths shown in FIG. 3 The axis of ordinates represents the superficial velocity of the press and the abscissa represents the position

angle of the plate cylinder.

  The rolling of the various sectors at a constant speed beyond the print right-of-way is represented by the X-intervals on the x-axis, and the rolling of the various variable-speed sectors is

  represented by the Y intervals on the x-axis.

  Clearly, the duration, in time, of each interval X is constant but the duration, in time, of the Y intervals varies according to the particular speed envelope 31, 32, 33, 34 or other available envelope which is used Keeping in mind that the printed material can be expected to be in the form of a continuous web moving at a speed of 10 V 1 equivalent to the surface speed of the printing plate 3 a, b on the constant velocity sector, the repetition length of the material (i.e. the length of film which passes beyond the printing cylinder during the time, in time, of the variable speed "Y), will vary according to the particular speed envelope chosen for the sector

variable speed.

  While in a conventional printing press, the variation of the repetition length as the repetition length and possibly also the space between each image of the above mentioned main panel and the following Subsidiary panel image would have required the removing a plate cylinder and replacing it with another plate cylinder of a different diameter so that the constant speed operation of the plate cylinder nevertheless allows a change in the repetition length, the press described above Referring to FIGS. 2 and 3, it is possible to avoid the need for such a change of the cylinder (with a time penalty of several tens of minutes) and allows the operator to modify the repetition length during the short time. switching. The optional possibility illustrated in FIG. 2 may also be useful if, instead of having two plates or plate regions 3a, 3b, there is a continuous plate on the "constant speed sector" and that the length of repetition between the image

  printed by this plate and the next image printed by this plate must be changed.

  It can be understood from reading the foregoing that the press according to the present invention offers a particularly advantageous result with regard to the printing of a packaging material, but nevertheless the possibility of varying the correspondence of the material printed in a monochrome press or in a multicolour press for any other application, offers a considerable improvement over the

  conventional direct-drive mode providing a much more limited match of the printed material.

  A particularly practical possibility for the press of the invention is that while up to now it was necessary for one press to be able to use and receive a group of many different plate cylinders of different diameters to change the repeat lengths. a press according to the present invention (having the possibility of "variable speed sector" can simply receive a single group of large-diameter plate cylinders (one per color) with the knowledge that shorter repetition lengths can be obtained using a velocity envelope such as 31 or 32 (FIG. 3) without requiring a change of the plate cylinder. In fact, with the plate plate mounting system (where a plate of any size is attached to a support sheet of a length exactly equal to the circumference of the plate cylinder so that the sheet can be easily When attached to the cylinder to mount the flexographic plate 35 on the cylinder 1), no "cover" movement of the plate cylinder or "cover" of the inking roller will be necessary. Thus, much more simplified presses having plate cylinders and Fixed-axis inking rollers are possible With the support sheet of the plate cylinder, a clamping or fastening system is used to ensure correct positioning of the plate with respect to the transverse reference axis or

  at the data line of the cylinder of the plate.

  Although, in the above description, motors 16 and 19 are described as stepper motors, it is of course possible

  to use any type of servo motor instead

a stepper motor.

  Another possible variant relates to the inking roller motor 11, which can be controlled in response to the main driving motor 6 of the printing cylinder 1 to a sufficiently high degree of accuracy to maintain a pure rolling contact of the platen roller. 2 and the inking roller 4, rather than securing the ink roller motor 11 directly to the cylinder engine

  plate 9, as described here.

R E V E V D I C A T IO N S

  1. rotary printing press, characterized in that it comprises at least one plate cylinder (2) and a rotatable support (1) of a printing material, a first motor (9) driving said plate cylinder and a second motor (6) driving said printed material carrier and a drive means (20) ensuring precise control of the rotational mutual position of said first and second motors to ensure a positional synchronization of a plate on said cylinder plate relative to said rotary support without requiring a mechanical interconnection between

  the plate cylinder and the support.

  2. Press according to claim 1, characterized in that the rotary support is a printing cylinder and the plate cylinder is arranged to form a printing grip between a plate on said plate cylinder and a medium passing on said

impression cylinder.

  3. Press according to claim 2, characterized in that it comprises an inking roller (4) arranged to be in rolling contact with a plate on said plate cylinder and driven by a third motor (11), the means of control being effective to maintain the rolling contact of the inking roller and the plate cylinder by controlling the position of the inking roller with respect to the impression cylinder or

cylinder ia.

  4. Press according to any one of claims 1 to 3, characterized in that it comprises means for moving the or each plate cylinder

  in the position of forming an impression relative to the rc-ative support, said means moving the cylinder to

  plate being controlled by the control means.

  5. Press according to any one of claims 3 or 4, characterized in that it comprises means for moving the inking roller in relation

  contacting a plate on the cylinder & plate, said means moving the ink roller being under the

control of the control unit.

  Press according to one of claims 1 to 5, characterized in that it is a multicolour press and comprises at least two plate cylinders, each carrying a plate for

  printing a color different from that of the other cylinder, each cylinder having its respective first motor, and the control means being effective to control the position of each plate cylinder with respect to the impression cylinder with which each

  of them forms a respective imprint of impression.

  7. Rotary printing press, characterized in that it comprises a rotatable support (1) of a material to be printed, at least one plate cylinder (2) adapted to support a plate on a portion of its cylindrical surface for rolling contact with an image transfer right-of-way, a first motor (9) for driving said plate cylinder, a second motor (6) for driving said rotary support, and control means (20) for controlling the position of the plate cylinder with respect to the rotatable support, said control means being effective for maintaining the positional relation at a constant surface velocity of said web to a first sector of rotation of the plate cylinder, and for varying the speed of said plate cylinder on a second rotational sector of said cylinder to change the time delay between the end of the first sector of a turn of the plate cylinder

  and the beginning of the first sector of the next turn of the plate cylinder.

  8. Press according to claim 7, characterized in that there are several plate cylinders and

  in that the control unit is effective for controlling the position and varying the rotational speed of each of the plate cylinders with respect to the motion of a common rotatable support.

  A press as claimed in claim 8, characterized in that the rotary support is a printing cylinder and that each plate cylinder forms a respective printing right-of-way with said printing cylinder. 10. Packaging plastics, characterized in that they are printed by a press according to one of

  any of the preceding claims.

  Packing plastic strip, characterized in that it is printed using the rotary printing press according to any one of

Claims 1 to 9.