EP0963294B1 - Flexographic printing machine - Google Patents

Abstract

The invention concerns a flexographic printing machine comprising a plurality of printers (2) and so-called feeding and tension means, for unwinding under tension and successively in each of the printers a strip-packed base stock to be printed (8), characterised in that each of the printers (2) is provided with said feeding and tension means (4, 6, 52) of the strip to be printed (8), comprising at least a fifth so-called support roll (4), movable (arrow 7) in the direction of a motoring roll of the printer (2), said motoring roll being any one roll of the roll unit comprising an impression cylinder (14) and the bar feeders (16, 18, 20, 22) such that the variations in tension of the strip (8), and therefore in strip length, inside a printer (2) are not passed on to the following printer (2).

Description

The invention is in the field of printing machines, and more particularly machines flexographic printing presses, and its purpose is a machine like that.

The printing technique flexographic consists in continuously scrolling a support banded in a succession of groups printing; to each of these, a color respective is printed on the support, by means of a plate supported by a rotary drum and previously inked. The successive inking of the support jointly draw at the end chain a pattern reproduced along the strip. We know thus printing machines formed in their generality of a plurality of successive workstations, including the so-called printing groups and groups drive belt arranged upstream and downstream of all the printing groups, so as to make scroll the support successively in these. The printing groups each include a plurality of rollers, rotary or mounted freely rotating according to various embodiments, including a plate roller against which the tape is applied by means of a roller presser, and a roller, called "anilox", for inking the plate holder ; training groups meanwhile, called respectively call and voltage, each include at minus a rotary roller, called call roller, against which is compressed the band for his training. Rolls of referrals, called bar feeders, are placed at the entrance and at the exit from each workstation, especially for orient the strip from one to the other of these. The rolls of all the printing units are from commonly rotated from at least one common motor, so as to obtain a drive rollers. According to a usual form of realization, the anilox are driven together in rotation from a first line of the drive shaft, while the rollers, plate holders and pressers are driven together in rotation from a second line motor shaft. Nevertheless and in an equivalent way, some machines have only one motor shaft line for the joint training of anilox on the one hand, and call rollers, plate holders and pressers on the other hand, declutching means nevertheless making it possible to break the rotational drive of the latter while continues the anilox rotation drive, to maintain the bubbling these into their respective ink tanks.

A technician-operator performs settings to each of the printing groups.

A first type of adjustment consists in adjust the contact, or key, of the different rollers, and in particular between the anilox and the plate holder for the transfer of ink on the one hand, and between the presser, the strip and the plate holder on the other hand. One difficulty posed lies in that the setting of the inking keys and printing is carried out by moving the rollers towards each other. However, the training of said rollers is performed for each of the printing groups by through a cascade gable, from the drive pinion of any of the rollers. The operator must therefore take into account the different games between the pinions when adjusting the keys, estimating their effect on the print result.

A second type of adjustment, called "print timing" is to position the image of each of the printing groups relative to the web, so as to obtain a pattern without offset at the end of the chain between the successively deposited colors. This kind of adjustment is carried out for example using a differential interposed between the motor shaft and the plate holder, so temporarily change the rotational speed of the plate holder in order to "put in phase" the cliché of the group printing being adjusted with the printing obtained to other printing units, until a pattern is obtained flawless. A difficulty posed lies in the fact that the belt tension between the different rollers of the machine is not identical and is difficult to control. In addition, the tension of the belt tends to vary and to pass from one printing group to another, depending band sliding forces on the different rollers without control possible by the operator. Through elsewhere, a slackening of the strip occurs during the reel change and key settings which arise. Finally, the presence of the above-mentioned games between the different sprockets in cascade drive rollers participate in the difficulty of setting the print.

Finally, we see that the role of the technician-operator is therefore to find a compromise between each of the printing groups taking into account, or even by exploiting the different uncertainty factors induced by the above-mentioned difficulties. These operations, which require a repetition of the different settings according to the print result, until satisfied, are long, tedious and therefore expensive, which pushes them designers to evolve the structure of the machines flexographic printing to facilitate the work of the technician-operator.

We also know by publication "Papier-Kunststoff-Verarbeiter" from September 1986, page 60.62, a flexographic printing machine in which each printing unit is equipped with means for printing tape, including a roller drive belt movable towards the roller presser, in order to obtain a precise adjustment and guidance of the band.

The object of the invention is therefore to offer a flexographic printing machine, the structure facilitates key setting and operator print timing, limiting the influence of the above uncertainty factors.

The inventive step consisted in break the habits taken in the field, and to replace to the so-called machine call and voltage groups flexographic printing of the above kind, means band training specific to each group printing, like the machine described by "Papier-Kunststoff-Verarbeiter" September 1986, page 60.62, of so that the tension of the tape in each of its own printing groups and does not undergo Inopportune variations due to the passage of the tape in a previous and / or next printing group. The so-called means band drive consist of means applying the tape against at least any of the already existing rollers of the printing unit, which is driven in rotation by transmission members specific to it, i.e. organs of transmission in direct connection to means of transmission motors, in particular so as not to be influenced by speed variations of the plate holder when setting the impression.

It follows from these provisions that the belt tension is specific to each group regardless of the web tension other printing groups, and finally that the operation of printing timing is made easier by the fact that the tape does not undergo voltage variations from from a previous and / or next printing group.

For example, the so-called motorized roller against which the tape is applied is any one at fewer of the printing group bargers; however, and pursuing their inventive approach, the Applicants propose to use the pressure roller as a drive roller of the band, and to provide the latter with means rotary drive comprising its own positive transmission, i.e. by example from a directly driven transmission gear by a drive shaft connected to the drive shaft line machine rollers, not from a sprocket participating in a cascade pignonnerie at which participate a pinion drive in rotation of the plate holder and / or Anilox, as in the Prior Art. Thanks to these provisions, the setting of the so-called printing key, between the strip and the plate holder, by a displacement of one to the other side of the plate or presser, do not not under the influence of a combination of gear sets, to take into account only a game specific to the organs of transmission of the movement of a motor member to the presser.

To complete the realization of a machine responding to the inventive step of the Seekers, these offer to motorize the bar feeders for each of the printing groups, in order to tend to make disappear the band tension variations over the whole sound path in each printing group, variations mainly due in the prior art to the efforts provided by the band against the respective inertia of different bar feeders who went crazy.

la fig.1 est une représentation schématique globale d'une machine à impression flexographique selon l'art antérieur,

la fig.2 est une représentation schématique globale d'une machine à impression flexographique selon une forme préférée de réalisation,

la fig.3 est une vue schématique d'un groupe d'impression d'une machine représentée sur la fig.2,

la fig.4 est une vue schématique en perspective d'un même groupe d'impression représenté sur la fig.3, illustrant les moyens d'entraínement en rotation des différents rouleaux correspondants.

The present invention will be better understood, and details will be apparent from the description which will be made of a preferred embodiment, in connection with the figures of the appended plates, in which:

FIG. 1 is a global schematic representation of a flexographic printing machine according to the prior art,

FIG. 2 is a global schematic representation of a flexographic printing machine according to a preferred embodiment,

fig.3 is a schematic view of a printing unit of a machine shown in fig.2,

Fig.4 is a schematic perspective view of the same printing group shown in Fig.3, illustrating the means for driving in rotation of the various corresponding rollers.

In fig. 1, a machine flexographic printing includes a plurality of groups printing, such as 2, and call groups and voltage 48 and 50 arranged downstream and upstream of the assembly printing groups 2. Call and voltage groups 48 and 50 include means, such as 78 and 80, called call and tension, to scroll under tension and successively in each of the printing groups 2 a printing medium 8 packaged in a strip.

Each printing group includes a set of parallel rollers: a first roller 10, said anilox, is intended for inking a supported plate around a second roller 12, called a plate holder, with a view to inking the support 8; a third roller 14, says presser, is intended to apply the strip 8 against the plate holder 12; finally, a set of at least two fourth rolls 20.18, known as input feeders 20 and outlet 18 for the one placed upstream and the one arranged in downstream of the presser 14, are provided to orient the strip 8 to inside printing group 2 and between two groups printing 2 neighbors.

Anilox 10 and any one less of plate holder 12 and presser 14 are movable (respectively arrows 1,3 and 5) with respect to the others for adjusting the contact, or key, between anilox 10 and plate holder 12 on the one hand for taking ink by the plate, and between the presser 14, the support 8 and the plate holder 12 on the other hand for the ink transfer of the photo on the support 8.

The anilox 10, the plate holder 12 and the presser 14 are rotated by means of at least a drive shaft line 24 and 26 common to all of the printing units, through a set positive transmission members comprising means 76, so-called phase adjustment, such as differential, allowing temporarily modify the speed of rotation of a plate holder corresponding to operate the print timing.

Note that the training optional in the prior art of each of the pressers 14, is carried out by means of a cascade gear from the drive members of the corresponding plate holder 12. According to another embodiment not shown in the figures, and in particular in the case of the presence of only one drive shaft line, plate holder 12 and incidentally the presser 14 are rotated from the anilox 10 drive gear.

In fig. 2 and 3, the process inventive of the present invention was to substitute to call and tension groups 48 and 50, which become superfluous in a machine of the invention, means of calling and tension 4,6 and 52 of the band 8 to be printed fitted each of the printing groups 2, so that the band 8 is held in each of printing groups 2 to avoid slipping on the different rollers, and finally that the voltage variations of the strip 8, and therefore of band length, within a group 2 are not passed on to the group print 2 next. These means of appeal and tension 4.6 and 52 include at least a fifth roller 4, says support, movable (arrow 7) towards a roller motorized printing unit 2, said motorized roller being any of the rollers in the roller group comprising the presser 14 and the bar feeders 20,16,18,22, and being rotated by transmission means positive (28.30) specific to it, directly linked to engine transmission means so as not to undergo the influence of a speed variation of the plate holder 12 during printing stalling.

Note that in a simple form and preferred embodiment and referring particularly in fig.3, said support roller 4 is, in the usual way in the field, consisting of a roller coated with a flexible material, especially rubber.

Means for moving the roller support 4 include a carriage 52, said first, movable by a power member 6, in particular a cylinder, the pressure exerted by the support roller 4 against the strip 8 towards the said motorized roller 14 or 16 or 18 or 20 or 22, and the stroke of the power member 6 being predetermined. We will note moreover that the support roller 4 is incidentally driven in rotation from the transmission members of the presser 14.

In Figs. 2,3 and 4, and according to a preferred embodiment, said motorized roller is constituted by the pressure roller 14, which is driven in rotation by motor means comprising a shaft line drive 24, said first, coupled to organs of positive transmission, 28 and 30 for example, called prime, specific to the presser 14, that is to say transmission 28.30 distinct from those, for example 32,34,36 and 74 or 38,40,42, rotational drive of any one at least the plate holder 12 and the anilox 10, and in particular transmission members 28 and 30 which are not placed under the influence of said phase adjustment means 76 of the plate holder 12.

Referring to fig. 3 and for each of the printing units, the means of moving the presser 14 preferably include a carriage 54, said second, guided in translation on a frame 56 of the machine, said second carriage 54 supporting at least the presser 14 and the support roller 4 with its means 6,52 for guiding and displacement towards the presser 14, and preferably those of the so-called input and output bargers 16 and 18 placed in the vicinity of the presser 14, directly upstream and downstream of it.

Note that the bar feeder input 16, called rectifier, located immediately upstream presser 14 is preferably placed, in the first place between the presser 14 and the output bar feeder 18 arranged immediately downstream of the presser 14, and secondly of so that its surface covered by the strip support 8 is located above the axis of the presser 14, such that so that the surface of the presser 14 covered by the support 8 be optimal.

Furthermore and preferably, the rectifier 16 is supported by the second carriage 54, together with the presser 14, so that the strip surface 8 covering presser 14 is constant whatever the movements of the second carriage 54, and so whatever the position of the presser 14 relative to to the plate holder 12, in order to avoid a shift in the position of the print media 8 relative to the transfer area ink.

According to usual forms of achievement in the field, everyone's means of mobility plate holders 12 and anilox 10, include a carriage, said respectively third 58 and fourth 60, guided in translation on the frame 56 of the machine. In addition, second 54, third 58 and fourth 60 carts are maneuverable in translation by means of a respective power (not shown in the figures), cylinder hydraulic in particular, precise adjustment of the key by additional movement of the carriages 54,58,60 by means of worm gear 82,64 and 66 respectively.

In fig. 4 and for each of printing units, the rotary drive means of the plate holder 12 advantageously include positive transmission 32,34,36,74 and 76 for example, said second, comprising said phase adjustment means 76, the first 28.30 and second 32.34.36.74 and 76 organs of transmission being coupled to the first shaft line drive 24, which is equipped with a device 62 clutch / disengage (fig. 2). Means of training in rotation of the anilox 10 preferably include organs positive transmission 38,40,42 for example, said third, coupled to a second line of drive shaft 26 separate from the first 24 rotational drive pressers 14 and plate holders 12. The drives in rotation of the pressers 14 and the plate holders 12 can be jointly disengaged by the device 62, while that continues the rotational drive of the anilox 10.

According to an alternative form of embodiment, not preferred and not shown in the figures, the plate holders 12 are rotated from the second line of drive shaft 26 in drive rotation of anilox 10; we will understand that this form of realization is equivalent to that described and represented, and that it comes under the invention, since the presser 14 is driven by transmission components from a drive line 24 or 26 independently of the other rollers, that is to say so that its rotation drive is not placed under the influence of the training of other rolls, and more particularly anilox 10 and of the plate holder 12, even in the case where this driving line 24 or 26 is common to all of the rollers 10, 12 and possibly 20,16,18,22 of the machine.

The third organs of transmission preferably include a flexible member of positive transmission 40 connecting the anilox 10 and the second line of drive shaft 26, in order to avoid shaking during training of the anilox 10, shaking detrimental to the uniform distribution of ink.

According to a preferred form of embodiment, the bar feeders 20, 16, 18 and 22 are driven in rotation by motor means which are not preferably not under the influence of the so-called phase adjustment means 76, so that the band 8 slips on the bar feeders be negligible to limit band tension variations inside each of the printing units 2.

Rotational drive means of each of the bar feeders 20,16,18,22 include for example positive transmission organs, including at least one organ flexible, such as 68, preferably coupled via a pinion 44 and 46 to the first drive shaft line 24 for rotating drive pressers 14 and plate holders 12, to be thereby placed under the control of said means 62 of engagement / disengagement.

Referring to fig. 2, and according to a preferred embodiment, the machine of the invention furthermore comprises at least one control and control, such as 70, of the various driving members 24, 26 and power (displacement cylinders of the various carriages 52,54,58,60), such as 6, of the machine. According to forms alternative embodiments, i.e. the control panel 70 is placed at the machine outlet to allow the technician operator overall management of the printing units from this desk, as shown in the figure, either, or in addition, the machine has several control desks command 70 respective to each of the printing groups 2.

Note also that the the invention is preferably equipped, at the exit of each printing units 2, usual drying stations, such as 72, of the tape to be printed.

Finally, note that although it is mentions means of the "differential" type to operate the printing timing, it should be understood that these means are not limiting as to the different forms of realization of said means 76 for adjusting the phase of the plate holder 12, these means 76 being able to be equivalently constituted by electronic control means associated with a pulse motor.

Also, although we have described a preferred form of the invention, it should be understood that the scope of the latter is not limited to this form, but that it extends to any printing machine comprising the characteristics set out above.

Claims (9)

1. Machine for flexographic printing, of the machine type comprising a plurality of printing groups (2) and means, known as draw-through and tensioning means, for unwinding a support to be printed upon (8) under tension and successively through each of the printing groups, each printing group (2) comprising an assembly of parallel rolls of which:

   a first roll (10), termed the anilox, is designed to apply ink to an engraved plate supported around a second roll (12),

   the said second roll (12), termed the plate carrier, is designed to support the plate with a view to applying ink to the support (8),

   a third roll, termed the pressure roll (14), is designed to apply the strip (8) against the plate carrier (12),

   for each of the printing groups (2), a set of at least two fourth rolls, termed feed rolls (20, 16, 18, 22), respectively inlet field rolls upstream from and run-out feed rolls downstream from the presser roll (14), are designed to orientate the strip (8) within the printing group (2) and between two neighbouring printing groups (2),

   such that the anilox (10) and any one of at least the plate carrier (12) and the presser roll (14) can be moved relative to one another in order to regulate the contact or 'touch', on the one hand between the anilox (10) and the plate carrier (12) for the take-up of ink by the engraved plate, and on the other hand between the pressing roll (14) and the plate carrier (12) for the transfer of ink from the plate to the support (8),
   the anilox (10), the plate carrier (12) and the pressing roll (14) being driven in rotation by means of at least one driving spindle (24, 26) via an assembly of positive transmission elements comprising means (76), known as phase regulation means, which make it possible to modify instantaneously the rotation speed of a plate carrier (12),
   characterised in that
   each of the printing groups (2) is equipped with the said draw-through and tensioning means (4, 6, 52) of the strip (8) to be printed upon, so that variations in the tension of the strip (8) and hence of its length within one printing group (2) will have no repercussions on the next printing group (2), the said draw-through and tensioning means comprising at least one fifth roll (4), known as the contact roll, which can be moved towards a driven roll of the printing group (2), the said driven roll being any of the rolls in the group of rolls comprising the pressure roll (14) and the feed rolls (16, 18, 20, 22), and being driven in rotation by positive transmission means (28, 30) specific to itself, directly connected to the motor transmission means in such manner that it is unaffected by a speed variation of the plate carrier (12) during the formation of the print.
2. Machine according to Claim 1,
   characterised in that
   the said driven roll in each printing group (2) is the pressure roll (14), which is driven in rotation by a drive spindle (24), termed the first spindle, by virtue of positive transmission elements (28, 30) termed the first such elements, which are not subject to the action of the said means (76) for regulating the phase of the plate carrier.
3. Machine according to either of the preceding claims,
   characterised in that
   the feed rolls (16, 28, 20, 22) are driven in rotation by driving means (24, 28, 44, 46, 68) which are not subject to the action of the said phase regulation means (76), such that the slippage of the strip (8) over the feed rolls (16, 18, 20, 22) is negligible in order to limit the tension variations of the strip (8) within each of the printing groups (2).
4. Machine according to Claim 2,
   characterised in that
   for each printing group, the means for displacing the pressure roll (14) comprise a carriage (54), termed the second carriage, which is guided in translation on a frame (56) of the machine, the said second carriage (54) supporting at least the pressure roll (14) and the contact roll (4) with its guiding and displacement means (6,52).
5. Machine according to claim 2,
   characterised in that

   for each printing group, the inlet feed roll (16), termed the straightening roll, arranged immediately upstream from the pressure roll (14), is located on the one hand between the pressure roll (14) and the run-out feed roll (18) arranged immediately downstream from the pressure roll (14), and on the other hand such that its surface covered by the strip support is located above the axis of thepressure roll (14),

   such that the area of the pressure roll (14) covered by the support roll (8) is optimal.
6. Machine according to claims 4 and 5,
   characterised in that

   for each printing group, the straightening roll (16) is supported by the second carriage (54) together with the pressure roll (14),

   such that the area of strip (8) covering the pressure roll (14) is constant whatever the movements of the second carraige (54), and therefore whatever the position of the pressure roll (14) relative to the plate carrier (12).
7. Machine according to claim 2,
   characterised in that

   for each printing group, the means for driving the plate carrier (12) in rotation comprise positive transmission elements (32,34,36,74,76), termed the second such elements that include the said phase regulation means (76), and the first (28,30) and second transmission elements (32,34,36,74,76) are coupled to the first drive spindle (24) which is equipped with a clutch engaging/disengaging device (62), and the means for driving the anilox (10) in rotation comprise positive transmission elements (38,40,42) termed the third such elements, coupled to a second drive spindle (26) different from the first spindle (24) that drives the pressure rolls (14) and the plate carriers (12) in rotation,

   such that the clutches of the pressure roll (14) and the plate carrier (12) drives can be disengaged together when the driving of the anilox rolls (10) in rotation is interrupted.
8. Machine according to Claim 7,
   characterised in that
   the third transmission elements comprise a flexible positive transmission element (40) that connects the anilox (10) and the second drive spindle (26) to one another.
9. Machine according to Claims 3 and 7,
   characterised in that
   the means for driving each feed roll (16, 18, 20, 22) in rotation comprise positive transmission elements that include at least one flexible element (68), which are coupled to the first drive spindle (24) that drives the plate holder (12) and the pressure roll (14) in rotation.

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