CH667425A5 - ROTARY PRESS PRESS, IN PARTICULAR FOR MULTICOLOR PRINTING. - Google Patents

Description

DESCRIPTION

The invention relates to a rotary printing press, in particular for multi-color printing, according to the preamble of the first claim.

It is known that a printing press only achieves good results if the positions of the printer plate and the printed medium are registered accurately. In various printing presses, other components are also available, which must also be kept in exact registration with the printer plate, B. is the case with the cloth in a rotary printing press.

Until now, a rotary printing press has required an exact setting so that the roller registration remained unchanged after the setting, with a limit in the degree of accuracy up to which the printing register could be set because the smallest change in registration with the distance of the engagement between the carrier for the printing plate , usually the plate cylinder, and the carrier for the medium to be printed, usually a Geis gene printing cylinder, was connected. A subordinate problem associated with this situation is that the thickness of the printing plate and / or a provided or reserve cloth that is fed to the plate cylinder under the plate must be carefully controlled because of the inability to compensate for the small variations in the radial distance of the plate surface from the axis of rotation of the plate cylinder to a degree of accuracy that is noticeably finer than a tooth spacing of the gear wheel. So far, the task of setting up a printing plate for an accurate registration of the printing process has required a precise listing of this radial distance of the plate surface from the plate cylinder so that the surface speed of the printing plate and the printed medium carried by the counter-cylinder can be adjusted to maintain the pressure registration. For a 3o effective printing process not only certain roller surfaces must always touch each other with the same parts, but the contact between all rolling surfaces should always be made with the same parts. But the contact between all rolling surfaces should also be a friction-free, pure rolling contact.

An object of the invention is thus to provide a rotary printing press with a plate cylinder and a rotating carrier for a material to be printed, a first motor driving the plate cylinder and a second motor driving the carrier for the material to be printed, and a device for securing it a precise control of the mutual rotational position of the first and the second motor is present. A positional synchronization of a plate on the plate cylinder with respect to the rotating carrier is to be ensured without it being necessary to provide a mechanical connection between the plate cylinder and the carrier.

The above problems are much more important when the printing press is a multi-color printing press that requires very accurate registration of many different plate cylinders, each bearing a different color with respect to the printed image printed by the other plates.

The object of the present invention is to provide a rotary printing press, in particular for multi-color printing, which does not have the disadvantages of existing designs.

The design to be created should enable gearless registration of the individual cylinders and rollers, so that gearboxes can be dispensed with.

60 The printing press according to the invention of the type mentioned is characterized by the features of the characterizing part of claim 1.

Exemplary embodiments of the rotary press according to the invention are explained in more detail with reference to the drawing. There 65 show:

1 is a diagrammatic representation of a printing press with a color unit with a plate cylinder group of a multicolour printing press, the counter cylinder of which is also indicated,

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Fig. 2 is a side view of part of the printer cylinder and the adjacent plate cylinder, according to a variant of Fig. 1, and

3 is a graphical representation of the peripheral speed of the printing plate in relation to the angular position of the plate according to FIG. 2.

In Fig. 1, an impression cylinder 1 is shown, which carries a coherent web to be printed, the z. B. can be a plastic sheet, not shown, for packaging material.

The coherent plastic web is to be provided with an imprint of at least two colors, a plate cylinder 2 carrying a plate 3 for one of these colors. Furthermore, an ink roller 4, preferably an anilox roller, is shown, which supplies the plate 3 with ink.

In conventional rotary printing presses, the plate cylinder 2 is mechanically connected via a gearwheel to the main shaft 5 of the impression cylinder, which rotates about the axis of rotation 5a in FIG. 1, while the anilox inking roller 4 is mechanically connected to the plate cylinder 2 via a gearwheel, with a frictionless one Contact between the finely profiled anilox roller 4 and the flexible flexographic printing plate 3 arises. The arrangement is designed so that the plate cylinder 2 can be withdrawn from contact with the impression cylinder 1 in order to displace the plate cylinder or otherwise provide access to the components of the press. The anilox ink roller 5 is in turn, for. B. for stopping the ink supply to the plate 3 in operation or during the plate change when setting the machine for printer operation from the plate cylinder 2 separable. This separability of the plate cylinder 2 from the impression cylinder 1 and the ink roller 4 from the plate cylinder 2 is still possible in the present embodiment.

Instead of the usual gears between the impression cylinder and the inking roller 4, the present embodiment provides three separate, precisely controlled drive motors which can be coupled to the relevant rotating components.

The impression cylinder 1 is driven by the motor 6 via a toothed belt pulley 7 on the drive shaft 5 and a toothed belt 8. In this case, the plate cylinder 2 is driven directly by a digitally controlled motor 9 at the end of the drive shaft 10 for the plate cylinder 2. In the same way, the ink roller 4 is driven by the digitally controlled motor 11 on the drive shaft 12.

So that the plate cylinder 2 and the inking roller 4 can be easily removed and replaced, quick-release couplings 13 are arranged on the drive shafts 10 and 12 next to the motors 9 and 11.

At each end of the drive shaft 10, a bearing block 14 is provided which is movable against and away from the drive shaft 5a for the counter cylinder 1 by means of a guide screw 15 which is rotated by a stepped motor 16.

Similarly, there is a bearing block 17 at each end of the drive shaft 12 for the inking roller, which can be moved toward and away from the drive shaft 10 for the plate cylinder by means of a guide screw 18 which is driven by a stepped motor 19.

According to the present invention, a controller 20 is provided for monitoring the speed and the rotational position of the motors 9 and 11 with respect to the speed and the rotational position of the counter-pressure cylinder, reference being made here to the angular position and the speed of the drive motor 6. The controller 20 also monitors the operation of the stepping motors 16 and 19. The control connection 21 between the controller 20 and the various motors 6, 9, 11, 16 and 19 is shown in FIG. 1.

The individual motors 6, 9 and 11 are connected to an encoder or function resolver for the position, which specifies the rotational position of the motor shaft and generates pulses for the control unit 20 so that it records the exact position of the counter-pressure cylinder 1, the plate cylinder 2 and the anilox ink roller 4 can determine.

A feedback of the position of the bearing blocks 14 for the plate cylinder 2 and that of the bearing blocks for the inking roller 4 takes place by means of a proximity determination device 22 for the bearing block 14 for the plate cylinder 2 and by means of a further proximity determination device 23 for the inking roller bearing block 17. Die Device 23 for the bearing block 17 determines its approach to the upright part of the bearing block 14 for the plate cylinder, while the device 22 for the bearing block 14 determines the approach to the upright part of the machine frame 24, not shown.

The main controller 20 comprises a microprocessor for the exact color setting of the positions of the three motors 6, 9 and 11 and also enables variations in the rotational position ratio as a function of control inputs from the manager with regard to pre-pressure and reprint.

The microprocessor also enables the motors 16 and 19 to be switched on separately in order to carry out a so-called covering movement of the plate cylinder cover, which is defined by the bearing blocks or supports 14 and those for the inking roller.

Such position-responsive and position-maintaining control devices are already known, and since the circuit details are not part of the present invention, we refer to them here

US-PS 4090116 (LIPPITT) from 16.5.78,

US-PS 4099107 (EDER) from 4.7.78,

U.S. Patent 4,344,127 (MC DANIEL) of Aug. 8, 1982, and U.S. Patent 4357561 (FENCI) of Nov. 2, 1982,

all of which describe similar circuits for closely monitoring the positions of movable elements.

The surprising property of the present invention is that it is possible to achieve and maintain an exact positioning of the rotating parts of the press, in the present case this using the impression cylinder 1, the plate cylinder 2 and the ink supply by means of the anilox ink roller 4 alone the main control 20 for the motors 6, 9 and 11 relates. This saves the high costs of conventional designs for the acquisition and wear of gears and for the time-consuming adjustment of the plate cylinder 2 with respect to the impression cylinder 1 when the plate cylinder is returned to the impression position. Furthermore, the previously high costs for changing the gear ratio when a plate cylinder with a different radial dimension is installed, namely by the controller 20 and the two motors 9 and 11 for the plate cylinder 2 and the inking roller 4.

By means of the exact position synchronization of the plate cylinder 2 and the inking roller 4 with respect to the counter-pressure cylinder 1, after the plate cylinder 2 has been removed from its counter-pressure position, it is possible to reset the plate cylinder to counter-pressure without maintaining a re-registration of the pressure due to the necessary registration by means of the controller 20. This ensures that the finely profiled, color-bearing anilox inking rollers 4 and the elastomer-flexographic printing plate on the plate cylinder 2 are in frictional contact with the rollers.

The use of separate, stepped motors 16 and 19 monitored by the controller 20 for covering the inking roller 4 and the plate cylinder 2 means that a simultaneous covering of all inking rollers and plate cylinders of a multi-color printing press with respect to the common impression cylinder is possible, so that all colors come back at the same time with the back pressure This greatly reduces the time required for coverage compared to the manual coverage that requires the manager to have each cylinder exactly the right distance from the counter-cylinder's axis of rotation 5a and with the correct angular orientation by registering the gear teeth of a conventional printing press , sets.

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Furthermore, it is easily possible for the designer to provide the control with a run registration, so that each individual plate cylinder touches the printed medium again by practically covering all the colors at the same time, and subsequently adjusting all positions of individual plate cylinders 2 for more precise registration takes place. In order for frictionless contact between the inking roller 4 and the printing plate 3 to take place during the run, the controller 20 must be able to change the rotational position of the inking rollers as a function of the changes in position of the plate cylinder, namely in relation to the diameter of the inking rollers 4 and Plate cylinder 2.

Printing registration can also be done by setting cylinders 1 and 2 at rest and, if necessary, by setting controller 20 before restarting the printing press. This ensures that when cylinders 1 and 2 return to their mutual rotational position, there is pure rolling contact on the circumference of the two cylinders 1 and 2 with correct pressure registration.

Another advantage of this design is due to the fact that the previous limitation of the smallest change with a small repeated length registration no longer exists. In contrast to previous mechanical limitations due to the tooth spacing on a gear, which prevented fine adjustment of repeated lengths, the pressure plate can now be expanded to a larger diameter and thus to a larger extent, provided that the number of pulses generated per revolution by each of the motors 6 , 9 and 11 are sufficient. Thus, there is a practically unlimited, variable setting possibility that allows a simple change in the multiplication ratio of the pulse ratios of different motors by using different suitable input signals to the controller 20.

A pressure fine adjustment is also made easier because hitherto a fine adjustment to an accuracy of less than one tooth spacing required an axial repositioning of the gear with helical teeth for the drive of the plate cylinder 2. It is now possible to carry out such an adjustment simply by temporarily reducing the speed of the plate cylinder in order to bring it into a new position in relation to the counter cylinder.

Other advantages of the present embodiment include a. as follows:

a) The replacement of a plate cylinder is now much faster than before because the plate cylinder previously had to be equipped with a gear that fit all plate cylinders of a certain size and was attached to the plate cylinder before it was installed in the press.

b) The for the disassembly of the printing press, for. B. time required for the color change is therefore much shorter than before, because no time is required to clean and re-register a transmission when the plate cylinder is returned to the counter-pressure position.

c) The big problem when attaching machine protection to the transmission is avoided.

d) The replacement of the printing plate and the cloth thickness on it are easier because small changes in the diameter of the combination of plate and plate cylinder can be adapted to the much finer setting of the speed ratio that is possible with the electronic control.

e) The occurrence of chatter marks caused by gearbox resonance in the print and the general vibration level of the printing press are reduced. The elimination of this transmission vibration leads to a reduction in the wear of bearings and other components of the printing press, which influence the positioning and the movement of the plate cylinders and / or the inking rollers.

The much finer setting allows the manager to make very small changes in the diameter of the plate cylinder, e.g. B. after regrinding the plate cylinder to compensate, so that the life of the plate cylinder can be greatly increased if it is used on a printing press of the present type.

FIG. 2 shows the function of an optimal embodiment shown in FIG. 1 if the correct main control 20 is used.

In the above description, it has been assumed everywhere that the rotation speed of the plate cylinder 1 remains practically the same in each sequence, provided the controller 20 is able to maintain and / or restore the registration due to small changes in the rotation speed of the plate cylinder 2 and the paint roller 4.

With the optimal property shown in FIG. 2, the positional relationship of the plate cylinder 2 with respect to the impression cylinder 1 only has to be maintained during the rolling movement of a sector AB of the plate cylinder beyond the pressure body. During this rolling movement, only a first plate or a first plate area 3a touches and prints a main image on the medium to be printed. Then there is an empty space corresponding to the sector BA, after which another plate or a plate area 3b prints a small section at the end of the medium to be printed, which z. B. a reference to a registered trademark can be at the bottom of a sack. However, it can also be an optical film registration mark for subsequent determination by a photoelectric converter if the printed medium is a coherent plastic web for packaging, e.g. B. is a chain of plastic bags.

During printing from plate area 3a and the subsequent printing from plate area 3b, an exact registration of the position of the plate cylinder 2 with the medium to be printed is required. In the case of a multi-color printing press, precise registration of the other plate cylinders together with the medium to be printed is also required. However, while the sector BA rolls past the print body, printing is not possible, and the absence of a relief printing plate zone at the sector BA makes it possible to vary the speed of the plate cylinder 2 if desired.

This type of speed variation is very useful because it allows the repetitive lengths to be changed either by increasing the speed of the plate cylinder 2 via the sector BA to shorten its lengths or by reducing this speed via the sector BA to extend these lengths. The repeated length is the distance on the printed material between two successive images from any plate or plate part 3a or 3b and thus the distance between the main part printed by the plate or plate part 3a and the subordinate plate part, that of the plate or is printed by the plate part 3b. However, the speed must be synchronized exactly when the sector AB is in the pressure position.

The embodiment with an optimal, repeated length variation according to FIG. 2 therefore requires that the main control 20 must be able to precisely synchronize the position of the plate cylinder 2 during the rolling movement of the sector AB, hereinafter referred to as “sector with constant speed”, past the pressure body, to adhere to. Furthermore, an increase or decrease in the speed of the plate cylinder 2 must be possible if the sector BA, hereinafter referred to as “variable speed sector”, rolls past the pressure body, depending on the restoration of an accurate positional registration at the end of the variable speed sector , so that the subordinate plate area can be correctly printed on the packaging material.

3 shows a possible variation in the repeated length in order to achieve the desired results. Curve 31 shows the shortest repetition length and that 32 shows a somewhat longer repetition, while curve 33 shows an even longer repetition length and curve 34 shows the longest of the four lengths. The ordinate shows the surface speed of the printing press and the abscissa the angular position of the plate cylinder.

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The rolling movement of the various sectors with constant speed past the pressure body is shown by intervals X on the abscissa and the rolling movement of the different sectors with variable speed is shown by intervals Y on the abscissa. It is clear that the duration for each interval X is constant, 5 but that the duration for the intervals Y varies depending on the particular length 31, 32, 33, 34 or others. If it is now taken into account that the printed material is a coherent web and moves at a speed v1 which corresponds to the speed of the plates 3a and 3b over the sector with constant speed, the repeated length of the material changes, e.g. B. the film length moving past the pressure body during the period of the sector with variable speed,

according to the speed selected for the variable speed sector. 15

In conventional printing presses, the variation in repeated length and possibly the distance between each image of the above main plate and the subsequent image of the sub-plate may require removal of the plate cylinder and replacement of another plate cylinder with one of a different diameter. Therefore, operation at a constant plate cylinder speed would allow the repeated length to be changed. The printing press described above with reference to FIGS. 2 and 3 does not need such an exchange of the plate cylinder, which means a great saving of time, but it is simply sufficient to actuate a switch.

The embodiment shown in FIG. 2 can also be useful if, instead of two plates 3a, 3b, a coherent plate is used across the sector at constant speed, and the repeated lengths between an image printed on the plate and that next picture printed from this plate.

From the above it can be seen that the present printing press offers particularly advantageous solutions with regard to the printing of packaging material. Nonetheless, this version for electronically varying the registration in a single-color or multi-color printing press for each application means a great advance over existing versions with fixed gear stages, which means a strong limitation of the printing registration.

A particularly well-suited option for the printing press according to the present invention is the fact that there has been a need hitherto for a printing press capable of using and with a set of many different plate cylinders with different diameters to change the repeated lengths to be delivered. A printing press according to the present invention with a variable speed sector can be operated with a single set of plate cylinders, i. H. one per color, with a large diameter. It is assumed that shorter repetition lengths can be achieved by using a curve 31 or 32 (speed envelope) (FIG. 3) without the need for cylinder replacement. With the so-called foil plate carrier system for plate mounting, there is no need for a covering movement of the plate cylinder or the paint roller. In this system, a plate of any size is attached to a carrier film with a length that corresponds exactly to the circumference of the plate cylinder, so that the film can easily be attached to the plate cylinder for mounting a flexographic plate on cylinder 1. This makes printing presses much simpler than before, with plate cylinders and ink rollers with fixed axes. The carrier sheet for the plate cylinder guarantees the correct positioning of the plate with respect to the transverse reference axis or date lines of the plate cylinder.

In the above description, motors 16 and 19 consist of stepped motors. However, it is also possible to use other types of servo motors.

As a further possible variant, the motor 11 for the inking roller, depending on the main motor 6 of the impression cylinder, can be precisely controlled such that a pure rolling contact takes place between the plate cylinder 2 and the inking roller 4, without the motor 11 for the inking roller from Motor 9 for the plate cylinder is dependent.

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Claims (9)

667 425 2nd PATENT CLAIMS 1. Rotary printing press with a plate cylinder and a carrier for the material to be printed, with a first motor for driving the plate cylinder and a second motor for the carrier, characterized in that it has a device (20) for controlling the mutual rotational position of the two motors has, so that a positional synchronization of a particular plate (3) on the plate cylinder (2) with respect to the rotating carrier (1) is guaranteed, namely without a mechanical connection between the plate cylinder (2) and the carrier (1). 2. Rotary printing press according to claim 1, characterized in that the carrier is an impression cylinder (1) and the plate cylinder (2) is arranged such that it forms a pressure body between a plate (3) on the plate cylinder (2) and a medium, that can be passed over the impression cylinder (1). 3. Rotary printing press according to claim 2, with an inking roller for rolling contact with a plate on the plate cylinder by means of a third drive motor, characterized in that the control device (20) for maintaining the rolling contact of the inking roller (4) with the plate cylinder (2), by controlling the position of the inking roller (4) in relation to said counter-pressure (1) or plate cylinder (2). 4. Rotary printing press according to one of the preceding claims with a first device for moving the or each plate cylinder into a counter-pressure position in relation to the rotating carrier, characterized in that the device is monitored by the control device (20). 5. Rotary printing press according to claims 3 and 4 with a second device for moving the ink roller in a contact relationship with a plate on the plate cylinder, characterized in that the device (19) for the ink roller (4) is monitored by the control device (20). 6. Rotary printing press according to one of claims 2 to 5 for multi-color printing, characterized in that it has at least two plate cylinders (2) for carrying a printing plate (3a, 3b) of one color, which of the or each other plate cylinder (2) deviates, each plate cylinder (2) being equipped with its own first motor (9), and the control device (20) for monitoring the position of each plate cylinder (2) with respect to the impression cylinder (1), with which each one is effective Forms pressure body. 7. Rotary printing press according to claim 1, with a plate cylinder which carries a plate (3a, 3b) which extends only over a rotation sector (BA) of its cylindrical surface, characterized in that the control device (20) for maintaining the positional relationship constant surface speed of the plate cylinder (2) over said first rotation sector (BA) of the plate cylinder (2) and for changing its speed via a second rotation sector (AB) of the plate cylinder (2) is effective. 8. Rotary printing press according to claim 7 for multi-color printing, characterized in that it includes a plurality of plate cylinders (2) and that the control device (20) for monitoring the position and for changing the speed of each plate cylinder (2) in relation to the movement of a common carrier (1) serves. 9. Rotary printing press according to claim 8, characterized in that the rotating carrier is an impression cylinder which forms a pressure body with each plate cylinder (2).