EP0363293A1 - Printing unit for a flexographic printing machine with a single impression cylinder - Google Patents

Abstract

A printing unit for a flexographic printing machine with an individual or single impression cylinder (10) comprises a plate cylinder (9) and an inking cylinder (11) which are mounted slidably on a frame (2) by means of supports (16, 25). To make it easier for the cylinders (9, 10, 11) to be moved and to be positioned relative to one another, the supports (16, 25), arranged on the same side of the longitudinal mid-plane of the web support to be printed, are mounted on the same guide shaft (17) fixed to the frame (2), and their movement is ensured by common means (36) for controlling a rapid approach and removal, to obtain the engagement and disengagement of the cylinders (9, 10, 11) relative to one another. <IMAGE>

Description

The invention relates to a printing unit for a flexographic printing machine with an individual or single counterpressure cylinder, comprising, on the one hand, a plate cylinder mounted mobile, by means of supports on the frame of said printing machine. flexographic printing, and an ink cylinder, combined with an inking device, and integral with a sliding support with respect to said frame and, on the other hand, prepositioning devices and fine adjustment means for positioning, with precision, the various cylinders between them.

The present invention relates to the field of printing and, more particularly, to manufacturers of printing units and, in particular, of flexographic printing machines.

Flexographic printing machines are, more particularly, intended for printing web materials such as cellulosic film paper, aluminum, plastics. For this purpose, they comprise one or more printing groups, their number depending on the successive layers which should be transferred to the strip so as to faithfully reproduce the composition of the colors composing the text or the image to be printed.

Also, flexographic printing machines have a frame on which the different printing groups are distributed. These are provided, more precisely, with a plate cylinder, on which the printing plates are mounted, and with a generally screened ink cylinder intended to transfer, according to a determined dosage, the ink coming from any anchoring device on said plate cylinder. It also cooperates with a counterpressure cylinder around which the strip is partially wound.

The flexographic printing machine is said to have an individual counterpressure cylinder when, for each printing group, it includes such a counterpressure cylinder cooperating with a plate cylinder. On the contrary, it is said to have a single counter-pressure cylinder when the latter is disposed in the center of the frame, the printing units being distributed around.

The quality of the printing depends, essentially, on the precise positioning of one of the cylinders constituting the printing group with respect to another which is adjacent to it.

Thus, the positioning of the ink cylinder must be adjusted to the layout of the printing cylinder, itself determined relative to the position of the counterpressure cylinder on the frame. However, a flexographic printing machine is intended to print strips in a variable format, this format directly depends on the diameter of the plate cylinder. Therefore, it can not occupy an immutable position on the machine frame. Likewise, the thickness of the support, in particular of the strip, depends on the material used and it is therefore necessary to be able to modulate the position of the plate cylinder with respect to the back pressure cylinder.

Also, according to a known arrangement, the plate cylinder is associated with a movable support mounted to slide on flat rectilinear slides arranged on the frame of the flexographic printing machine. As for the ink cylinder and the associated inking device, they depend on a slide mounted on slides equivalent to those mentioned above, arranged on the movable support of the plate cylinder.

Therefore, it is possible, by means of motor means, manual or automatic, to proceed, on the one hand, to the displacement of the plate cylinder relative to the counterpressure cylinder, fixed on the frame and, on the other hand , to get a relative displacement of the ink cylinder with respect to said plate cylinder.

Since the print quality depends on the precision in the positioning of the different cylinders constituting a printing group, use is made, initially, of a prepositioning device making it possible to obtain a rapid approach or release of the printing support. on the frame of the flexographic printing machine and the slide, provided with the ink cylinder, with respect to said plate support. At the same time, a printing unit includes fine adjustment means, with manual or motorized control, making it possible to position, exactly, the plate cylinder with respect to the counterpress cylinder and the ink cylinder with respect to said plate cylinder.

The disadvantages of the known printing units applied to current flexographic printing machines consist essentially of their complexity, in particular, in terms of the means involved in the mobility of the different cylinders relative to each other.

Initially, it will be noted that the design of the flat rectilinear slides arranged, on the one hand, on the frame and receiving the plate support and, on the other hand, produced on the latter and favoring the displacement of the slide provided with the ink cylinder is particularly delicate . Indeed, these flat rectilinear slides require, beyond a milling operation, a rectification phase followed by manual scraping of the surface. This results in a significant machining time requiring a manual phase which has the consequence of increasing the cost price of the flexographic printing machine.

Furthermore, it should be noted that both the prepositioning devices and the fine adjustment means use separate motor means depending on whether it is a question of moving the plate support or the slide provided of the ink cylinder. This mechanical complexity only amplifies the previous consequences.

Other disadvantages of known printing units lie in the means used, on the one hand, to temporarily release the different cylinders from each other in the event of temporary printing stoppage, and, on the other hand , to ensure their return to the printing position without the use of fine adjustment means.

Very often, electrical or electronic devices are used to locate and memorize the printing position of the printing cylinder and the ink cylinder. Also, if these cylinders are released from one another, controlled by manual or automatic motor means, the electronic or electric locating means facilitate the task for the operator to quickly bring the various cylinders back to the printing position or, are able to actuate and control the operation of the automatic motor means in order to guarantee a systematic and precise return of the cylinders to their engagement position.

Such a solution contributes to the complexity of the whole and requires the use of more sophisticated equipment. Indeed, the effectiveness of these electrical or electronic tracking means is only real, under the condition, where they are associated with automatic and non-manual motor means. However, to guarantee accuracy in the positioning of either the plate cylinder with respect to the counterpressure cylinder or the ink cylinder with respect to said plate cylinder, it is necessary that the electronic information communicated by the locating device be faithfully translated by the means motors in a well-defined displacement length, either from the plate support or from the slide fitted with the ink cylinder. Now, this fidelity can only be achieved by the use of relatively expensive servo motors.

The object of the present invention is to remedy all of the aforementioned drawbacks by proposing a printing unit whose motor means of the prepositioning device are identical with regard to the printing cylinder and the ink cylinder. In addition, this printing unit includes mechanical storage means of the printing position of the different cylinders which are able to disregard any play existing between the mechanical connections and which, moreover, are liable to limit the amplitude of the clearance between the cylinders in the event of temporary printing stoppage. Such mechanical storage means, moreover, avoid the use of complex and expensive motor means such as servo motors.

The invention as characterized in the claims solves the problem of creating a printing group for flexographic printing machine with individual or single counterpressure cylinder comprising, on the one hand, a plate cylinder mounted movable by the intermediary of supports, on the frame of said flexographic printing machine, and an ink cylinder, combined with an inking device and integral with supports sliding on said frame and, on the other hand, prepositioning devices and means fine adjustment for positioning, with precision, the different cylinders between them, the supports, arranged on one side of the longitudinal median plane of the support in strip to be printed, of the plate cylinder and of the ink cylinder, being mounted sliding on the same shaft guide, integral with the frame, and being actuated by means of common approach and quick release control means to ensure engagement t or the clearance between the cylinders.

• - la figure 1 représente une vue partielle schématisée et en perspective d'un groupe d'impression conforme à la présente invention ;
• - la figure 2 illustre, de manière schématique, les dispositifs de prépositionnement et les moyens de réglage fin intervenant sur le cylindre cliché et le cylindre encreur afin de positionner ces derniers par rapport au cylindre de contrepression ;
• - la figure 3 représente une vue en plan de la figure 2 et dans laquelle sont représentés les moyens d'entraînement des différents cylindres constituant un groupe d'impression conforme à l'invention ;
• - la figure 4 représente une vue en élévation et en coupe partielle d'un groupe d'impression, cette figure illustrant un mode d'exécution préférentiel des moyens de réglage fin et des dispositifs de prépositionnement d'un cylindre cliché et d'un cylindre encreur ;
• - la figure 5 représente, schématiquement, en coupe partielle et selon un premier mode de réalisation, les moyens de mémorisation mécanique de limitation de la course de recul des différents cylindres, clichés et encreurs par rapport au cylindre de contrepression, lors des interruptions d'impression ;
• - la figure 6 représente une vue en coupe selon VI-VI de la figure 5 ;
• - la figure 7 représente, schématiquement, en coupe partielle et selon un second mode de réalisation, lesdits moyens de mémorisation mécanique ;
• - la figure 8 représente, schématiquement, en coupe partielle et en élévation, les moyens de mémorisation mécanique tels qu'illustrés dans la figure 7.

The invention is set out below, in more detail, with the aid of drawings representing only one embodiment.

• - Figure 1 shows a partial schematic perspective view of a printing unit according to the present invention;
• - Figure 2 illustrates, schematically, the prepositioning devices and the fine adjustment means acting on the plate cylinder and the ink cylinder in order to position the latter relative to the backpressure cylinder;
• - Figure 3 shows a plan view of Figure 2 and in which are shown the drive means of the different cylinders constituting a printing unit according to the invention;
• - Figure 4 shows an elevational view in partial section of a printing unit, this figure illustrating a preferred embodiment of the fine adjustment means and prepositioning devices of a plate cylinder and a cylinder inker;
• - Figure 5 shows, schematically, in partial section and according to a first embodiment, the mechanical storage means for limiting the recoil stroke of the different cylinders, plates and inks relative to the counterpressure cylinder, during interruptions of impression ;
• - Figure 6 shows a sectional view along VI-VI of Figure 5;
• - Figure 7 shows, schematically, in partial section and according to a second embodiment, said mechanical storage means;
• FIG. 8 schematically represents, in partial section and in elevation, the mechanical storage means as illustrated in FIG. 7.

We refer more specifically to Figure 1.

The present invention relates, more particularly, to a printing unit 1 for a flexographic printing machine intended for printing materials in strips such as paper, cellulose film, aluminum, plastics or others.

In general, a flexographic printing machine comprises a frame 2 composed of a front wall 3 and a rear wall 4 arranged on either side of the longitudinal median plane of the support in strips to be printed. On this frame 2 are distributed one or more printing groups 1, the number of which depends, more precisely, on the successive layers which should be transferred to the strip support. Also, are there flexographic printing machines comprising two, four or six printing groups, generally distributed symmetrically with respect to a vertical median plane, transverse to the longitudinal axis of the strip.

A flexographic printing machine is said to have a single counterpressure cylinder when it comprises, in the center of its frame 2, a single counterpressure cylinder around which the different printing groups are distributed 1. In contrast, the flexographic printing machine is said to have an individual pressure cylinder when each of its printing units cooperates with a generally smaller diameter pressure cylinder.

Frequently, such flexographic printing machines with individual counterpressure cylinders are able to adapt to more varied printing conditions and, in particular, when the strip support is printed on both sides. This type of flexographic printing machine allows, in addition, to design frames 2 of modular type, each of the modules comprises, as shown in FIG. 1, a front wall 5 and a rear wall 6 having support means 8 for a printing unit 1. These modules are intended to be superimposed on each other or even juxtaposed so as to give the flexographic printing machine a structure symmetrical with respect to a vertical median plane, transverse to the longitudinal axis of the strip.

It will be noted, however, that the present invention relates to a printing unit 1 which can be adapted both on flexographic printing machines with single counter cylinder or with individual counter cylinder comprising a frame of immutable dimensions or of modular nature .

The present description of a printing unit 1, in accordance with the invention, will apply, more particularly, to a flexographic printing machine with individual counterpressure cylinder and the frame of which is of the modular type. However, in view of this description, it will be easy for those skilled in the art to adapt this printing unit 1 to any type of model of existing flexographic printing machine.

Thus, the printing unit 1, object of the present invention, comprises, as known, a plate cylinder 9 cooperating with a counterpressure cylinder 10 and supporting all of the plates which it is necessary to transfer to the strip. to be printed. In fact, it passes between the counterpressure cylinder 10 and said plate cylinder 9.

The latter cooperates, moreover, with an ink cylinder 11 which is juxtaposed to it and disposed, generally, diametrically opposite the counterpressure cylinder 10. The ink cylinder 11, very often screened, is intended to transfer, according to a determined dosage , the amount of ink on the plate cylinder 9 and, for this purpose, it is combined with an inking device 12 with features independent of the present invention.

Since the printing unit 1, according to the invention is strictly symmetrical with respect to the longitudinal median plane of the strip, only the description of its structure cooperating with the front wall 3 of the frame 2 will be described in detail.

Thus, the plate cylinder 9 is mounted on a shaft 13 having ends 14 pivotally mounted in the bearings 15. These are integral with a support 16 slidingly mounted on the frame 2 of the flexographic printing machine. Contrary to what is usually adopted, this support 16 does not rest on a flat rectilinear slide arranged on the front wall 3 or rear 4 of the frame 2 but is, according to the invention, mounted on a shaft 17 fixed securely, to its ends 18 and 19, to said front wall 3 or rear 4 of the frame 2 parallel to the longitudinal axis of the strip to be printed.

The advantage that such a guide shaft 17 has compared to a flat rectilinear slide consists, essentially, in that it is easier to use, therefore less expensive, and that it provides precision in guidance substantially superior.

Of course, the diameter of this guide shaft 17 will be determined so as to avoid possible buckling under the effect of the weight of the cliché cylinder 9 and of the inking cylinder 11. However, to substantially relieve, for example, the weight of the cliché cylinder 9, the support 16 associated therewith can rest, in its lower part 20, on a guide ramp 21 arranged under said guide shaft 17.

Like the plate cylinder 9, the ink cylinder 11 is mounted on a shaft 22, the ends 23 of which are engaged in bearings 24 secured to a support 25 also slidably mounted on the guide shaft 17. On this support 25 is also mounted the inking device 12 transferring the ink onto the inking cylinder 11.

Still with the aim of avoiding possible deformations of the guide shaft 17 and thus guaranteeing a certain precision and printing quality, this support 25 cooperating with the ink cylinder 11 may have, on its underside 26 , a shoe 27 possibly resting on a guide ramp 28 located in the extension of the guide ramp 21 on the front wall 3, 5 or rear 4, 6 of the frame 2 or one of the modules constituting the latter.

It will be noted that another advantage provided by the arrangement adopted within the framework of the present invention consists in that the guiding both of the support 16 of the plate cylinder 9, and of the support 25 of the ink cylinder 11, is limited to a single shaft. guiding 17. In the context of the prior art, the superimposition of the support corresponding to the plate cylinder and the support associated with the ink cylinder required the production of two particularly delicate flat rectilinear guides.

Of course, the mobility conferred on the plate cylinder 9 and the ink cylinder 11, due to the sliding mounting of the supports 16 and 25 on the guide shaft 17, has the essential function, on the one hand, of making it possible, in the event of printing stop, the release of the plate cylinder, with respect to the counterpressure cylinder 10, and the ink cylinder 11 with respect to said plate cylinder 9. On the other hand, this mobility allows the interchangeability of the plate cylinder 9, in order to '' ensure printing of a support in strips according to variable formats by means of the same flexographic printing machine.

The precision in the extension of the different cylinders between them of a printing unit 1 is decisive as to the quality of the printing provided at the level of the support in bands. Also, the printing unit comprises, on the one hand, prepositioning devices 29, 30, respectively, of the plate cylinder 9 with respect to the counterpressure cylinder 10 and the ink cylinder 11 with respect to said plate cylinder 9, and on the other hand, fine adjustment means 31, 32 of these same cylinders 9, 10, 11 between them.

Preferably, the prepositioning devices 29, 30 consist of shims of format 33, 34 interposed, on the one hand, between the support 16 of the plate cylinder 9 and a stop 35 disposed at the end 18, located on the side of the cylinder of back pressure 10, of the guide shaft 17 and, on the other hand, between said support 16 and the support 25 of the ink cylinder 11. The length of these shims of format 33, 34 is determined according to the printing format, therefore the diameter of the plate cylinder 9.

The printing unit 1 further comprises means for approach control and quick release 36 of the different cylinders 9, 10 and 11 between them. Advantageously, these rapid approach and release means 36 consist of a jack 37 whose body 38 is of the mobile type and constituted by the support 25, while the piston 39 is mounted fixed on the guide shaft 17.

Figures 2 and 4 respectively illustrate, schematically and in detail, these means of approach control and quick release 36 formed by a cylinder 37. Also, can we realize that the support 25 of the ink cylinder 11 comprises a cylindrical recess 40 traversed right through by the guide shaft 17 and of diameter 41 substantially greater than the latter. The piston 39, fixedly mounted on the guide shaft 17, subdivides this cylindrical recess 40 into two chambers 42, 43 between which a fluid is conveyed so as to ensure, as the case may be, the bringing together of the different cylinders between them or their clearance when printing stops. More specifically, the operation of these approach and quick release control means 36 is as follows:
- when it comes to bringing the different cylinders into contact with each other, in order to start printing a support in strips, the laminating fluid is introduced into the chamber 42 delimited by the piston 39 and a closure cap 44 sealingly seal the cylindrical recess 40 at its end 45 oriented towards the counterpressure cylinder 10, the support 25 of the ink cylinder 11 then slides along said guide shaft 17 so to cooperate with the block of format 34, the latter pushing the plate support 15 applied against the block of format 33 immobilized by the stop 35;
- unlike, in the event of injection of the laminating fluid into the chamber 43, the support 25 of the ink cylinder 11 recedes until it reaches the rear stop 46 located at the end 19 of the guide shaft 17. Au during this progression and beyond a stroke of determined length, the support 25 of the ink cylinder 11 causes the drive, via a mechanical connection, described above, of the support 16 with which the cylinder is associated Plate 9. It can be seen, as it only requires single motor means to cause the advance or the retreat both of the plate cylinder 9 and of the ink cylinder 11.

Furthermore, in view of what is described above, it should be noted that said approach and quick release control means 36 constitute, in addition, means for setting the plate cylinder 9 and the ink cylinder 11 in printing position. Indeed, it suffices to keep a certain pressure of the rolling fluid in the chamber 42 of the jack 37 to simultaneously maintain the stop 18, the shim 33, the support 16, the shim 34 and the support 25 contact with each other. This is a definite advantage since it is no longer necessary to use wedging means additional. This reduces the complexity of the mechanism of a printing unit 1.

As for the fine adjustment means 31 of the plate cylinder 9 with respect to the counterpressure cylinder 10, these consist of the stop 35, of adjustable nature, mounted on the end 18 of the guide shaft 17. In fact, this stop 35 is formed by a cylindrical end piece 47 secured to the front wall 3 or rear 4 of the frame 2 having on its outer periphery, a fine thread 48 cooperating with a thread 49 machined in the bore of a socket 50. That it is able to pivot due to a ball stop 51 interposed between said bush 40 and the front edge 52 of the shim of format 33.

The sleeve 50 further comprises, on its outer periphery 53, a toothing 54 cooperating with a pinion 55 mounted at the end 56 of a transmission shaft 57. The latter extends parallel to the guide shaft 17 , substantially, up to the level of the end 19 thereof and cooperates with manual or automatic control means 58.

According to the preferred embodiment shown in the figures, this transmission shaft 57 comprises, at its free end, a pinion 59 meshing on a worm screw 60 mounted in free rotation in a housing 61, solidiare of the front wall or rear 3, 4 of the frame 2. Said worm screw 60 is rotated either manually, by means of an easily accessible flywheel 62, or by means of suitable motor elements.

Thus, by actuating said flywheel 62, in one or the other direction, it causes, simultaneously, the rotation of the sleeve 50 and its translation on the cylindrical end piece 47. This results in the advancement or retreat of the 'one of the supports 16 located at the ends 14 of the plate cylinder 9. The fine thread 48 machined on the cylindrical end piece 47 ensures a precision adjustment on which the quality of the printing will depend.

It will also be noted that the transmission shaft 57 is kept, in free rotation, at its ends 63, 64 in bearings 65, 66 arranged in the front wall 3 or rear 4 of the frame 2.

As for the adjustment means 32 of the ink cylinder 11 relative to the plate cylinder 9, they are similar to the fine adjustment means 31 described above. Also, the closure cap 44 is extended, in its external part, with a cylindrical end piece 67 provided, on its external periphery, with a fine thread 68 cooperating with a thread 69 machined, according to an equivalent pitch, in the bore a sleeve 70. This is kept pivoting relative to the axis of the guide shaft 17 due to a ball stop 71 interposed between said sleeve 70 and the front edge 72 of the shim 34 .

The sleeve 70 further comprises, on its outer periphery 73, a toothing 74 intended to cooperate with a pinion 75 mounted at the end 76 of a transmission shaft 77 arranged parallel and below the guide shaft 17. Preferably, this transmission shaft 77 is mounted in bearings 78, 79 integral with the support 24 of the ink cylinder 11. It also comprises, at its opposite end 80, manual or automatic control means 81. In the context of the mode shown in the figures, these control means 81 consist of a pinion 82 mounted at the end 80 of this transmission shaft 77 and cooperating with an endless screw 83 arranged, free to rotate, in a fixed housing 84 on said support 25 of the ink cylinder 11. From this housing 84 emerges a pin 85 cooperating, at one of its ends, with said worm screw 83 and comprising, at its outer end, a handwheel 86.

It is obvious that, due to the mobility of the ink cylinder 11, the fine adjustment means 32 are totally associated with it and not dependent on the frame 2.

As in the context of fine adjustment means 31, the mode of operation of which is described above, the rotation of the handwheel 86 causes the sleeve 70 to rotate and, simultaneously, the translation of the latter on the cylindrical end piece 67. Said socket 70, cooperating by means of the ball bearing 71, with the format shim 34, causes either the advancement or the retreat of the ink cylinder 11 relative to the plate cylinder 9.

Of course, as already specified above in the description, the prepositioning devices 29, 30 and the fine adjustment means 31, 32 are found both on one side and the other of the printing unit 1, so to be able to intervene on the parallelism of the different cylinders 9, 10 and 11 between them.

According to the invention, the printing unit 1 further comprises mechanical means 87 for limiting the recoil stroke of the plate cylinder 9 with respect to the counterpressure cylinder 10 and of the ink cylinder 11 with respect to said plate cylinder 9.

In fact, these mechanical means 87 consist of stop means 88, 89 capable of limiting the amplitude of movement of the plate cylinder 9 relative to the counterpressure cylinder 10, on the one hand, and of the ink cylinder 11 relative to the plate cylinder 9, on the other hand, and this, when ordering temporary printing out. This limitation avoids the degeneration of the drive pinions of the cylinders.

More precisely and according to a first embodiment, the stop means 88 serving to limit the back stroke of the plate cylinder 9 relative to the counterpressure cylinder 10, consist of a stop body 90 made integral with the front or rear wall 3, 4 of the frame 2 substantially in the same vertical plane as the end 18 of the guide shaft 17. This abutment body 90 has a central bore 91 having a first recess 92 serving as a housing for the means 93 capable of limiting the displacement of one of the supports 16 of the plate cylinder 9 on the guide shaft 17. A second recess 94 , of larger diameter, machined in the central bore 91, authorizes the introduction of a retaining ring 95 holding the means 93 at the step 92.

As regards more specifically, the means 93, these consist of an elastic return ring 96 capable of moving axially, inside the recess 92, over a predetermined stroke 97.

In fact, the thickness 98 of the elastic return ring 96 is reduced by the length of the stroke 97 relative to the depth 99 of the recess 92 machined in the central bore 91.

In addition, elastic return means 100 constituted, for example by helical springs, hold, in abutment the elastic return ring 96 against the internal face 101 of the retaining ring 95. According to a preferred embodiment, these elastic means 100 or helical springs are introduced into blind holes 102 arranged on the rear face 103 of the elastic return ring 96 and cooperating with the shoulder 104 defined between the recess 92 and the central bore 91.

Also, in view of the above description, it is understood that by immobilizing, with respect to the elastic return ring 96, one of the supports 16 of the plate cylinder 9, in particular, when the latter is in the printing position. , said support 16 would only be able to move over a length equivalent to the stroke 97 at the time of its temporary printing out. The return to the printing position is obtained, in this case, by the simple fact of the action of the jack 37 causing the advance of the support 16 until the coming in abutment of the elastic return ring 96 against the internal face 101 of the retaining ring 95.

However, it will be understood that the position of the elastic return ring 96 relative to one of the supports 16 of the plate cylinder 9 cannot be immutable due, in particular, to variable printing formats and to a certain freedom that it is necessary to confer on said support 16 during the various clearances or rapid approaches or even fine adjustments of the plate cylinder 9 relative to the counterpressure cylinder 10. In summary, this immobility of the elastic return ring 96 relative to said support 16 must not be obtained only when all the adjustments of the plate cylinder 9 with respect to the counterpressure cylinder 10 have been made.

This is made possible by means of transmission 105 of specific characteristic, in accordance with the invention.

Thus, according to a preferred embodiment of the latter, these transmission means 105 consist of a tubular central axis 106, parallel to the guide shaft 17 and made integral, by means of connection means 107, one of the supports 16 of the plate cylinder 9. This tubular axis 106 is crossed by a shaft 108 cooperating, at one of its ends 109, with locking means 110 situated in the axial extension of the tubular axis 106 and capable of acting on the elastic return ring 96. Furthermore, at its opposite end 11, this shaft 108 includes manual or motorized rotation drive means 112.

More precisely, by acting on the drive means 112, locking means 110 act so that the elastic return ring 96 is made integral in translation with the support 16 limiting the movement of the latter to the single stroke 97.

As for these locking means 110, they consist of a cylindrical mandrel 113 with expandable jaws 114 capable of cooperating with the internal bore 115 of the elastic return ring 96. In fact, the cylindrical mandrel 113 is split lengthwise so as to receive said expandable jaws 114, these cooperating, in their internal part 116, with a wedge-shaped locking member 117. Also, by causing the advancement of said wedge-shaped locking member 117, under the expandable jaws 114, these are caused to move away from the central axis 118 of the cylindrical mandrel 113 annihilating the play existing between the latter and said elastic return ring 96.

The engagement or withdrawal of the wedge-shaped locking member 117 is obtained due to the presence of a threaded orifice arranged in the latter and cooperating with a threaded end piece 119 located in the extension and at the end 109 from tree 108.

It will be noted that the return to the position of withdrawal of the expandable jaws 114 is obtained by means of circlips 120 of elastic nature enclosing the cylindrical mandrel 113 at its ends 121 and 122.

In view of the above description, it is understood that the operating mode of these mechanical means 87 for limiting the recoil stroke of the plate cylinder 9 relative to the counterpressure cylinder 10 and, more precisely, those of the stop means 88, is the following :
- once said stereotype cylinder 9 is perfectly positioned relative to the counterpressure cylinder 10, the operator actuates the drive means for manual or motorized rotation 112 causing the rotation of the shaft 108 in the tubular axis 106 and, finally, the translation of the wedge-shaped locking member 117 on the threaded end piece 119, this results in the immobility of the elastic return ring 96 relative to the cylindrical mandrel 113 which, for its part, is directly located in the axial extension of the tubular axis 106 and, therefore, integral in translation with the latter;
- Then, by actuating the jack 37 to cause the ink cylinder 11 and the plate cylinder 9 to retreat, the latter will necessarily be limited to the stroke 97 of the elastic return ring 96 in the stop body 90;
- unlike, in the event of an unlocking command and final printout, the opposite direction of rotation of the shaft 108 causes the wedge-shaped locking member 117 to be removed and, ultimately, the expandable jaws 114 relative to the outer periphery 123 of the cylindrical mandrel 113. The support 16 of the plate cylinder 9 is thus dissociated from the elastic return ring 96. Whatever the position occupied by the latter at this instant, the elastic means 100 cause its return in abutment against the internal face 101 of the retaining ring 95. This systematic positioning of the elastic return ring 96 relative to a reference surface is imperative to guarantee a recoil stroke of the plate cylinder 9.

As for the stop means 89, constituting the mechanical means 87 for limiting the recoil stroke of the ink cylinder 11 relative to the plate cylinder 9, these borrow an identical configuration to the stop means 88 and constitute, in fact, their symmetrical with respect to a vertical median plane 124 passing through the connecting means 107 connecting the tubular axis 106 to the support 16. These stop means 89 thus come to be interposed between the manual or motorized rotation drive means 112 mentioned above and the end 111 of the shaft 108 housed in said tubular axis 106.

More specifically, said stop means 89 consist of a stop body 125 made integral, in this case, with a support 25 of the ink cylinder 11 and having a central bore 126. In the latter, a first recess 127 is produced serving as a housing for means 128 capable of limiting the movement of the ink cylinder 11 relative to the plate cylinder 9 and a second recess 129 receiving a retaining ring 130. Just as before, the means 128 consist of an elastic return ring 131, movable in translation, along a stroke 132, in the recess 127 defined inside the central bore 126. Elastic means or helical springs 133 hold said return ring elastic 131 against the internal face 134 of the retaining ring 130.

The symmetrical arrangement of these abutment means 89 with respect to the abutment means 88 described above is essentially due to the fact that, unlike the latter, the abutment body 125 is caused to move relative to said elastic return ring 131. The latter is, in fact, immobilized in translation relative to blocking means 135 cooperating with the transmission means 105 connected to the support 16 of the plate cylinder 9.

The locking means 135 are constituted by a cylindrical mandrel 136 split in its length so as to accommodate expandable jaws 137 cooperating with a wedge-shaped locking member 138. This is provided with a threaded bore 139 through which a threaded end piece 140, extending the shaft 108 at its end 111. This threaded end piece 140 is provided, at its free end 141 with manual or motorized rotation drive means 112.

Due to the symmetrical arrangement of the stop means 88 with respect to the stop means 89, the threads machined on the threaded ends 119 and 140 are necessarily in opposite directions so that the drive of the shaft 108 causes the erasure or the simultaneously engaging wedge-shaped locking members 117 and 138 under the expanding jaws 114 and 137.

Thus, once the different cylinders 9, 10 and 11 are positioned relative to each other, by means of the prepositioning devices 29, 30 or the fine adjustment means 31, 32, the control means are controlled. manual or motorized rotation drive 112 causing the immobility of the elastic return rings 96 and 131 on their respective cylindrical mandrel 113 and 136. These being directly connected to the transmission means 105 integral with the support 16 of the plate cylinder 9, there is an intimate connection between the front or rear wall 3, 4 of the frame 2 and the support 16, on the one hand, and between this last and the support 25 of the ink cylinder 11, on the other hand.

In fact, the control of the jack 37 by injection of rolling fluid into the chamber 43, causes, initially, the withdrawal of said support 25 from the ink cylinder 11 along a stroke 132 delimited by the play existing between the stop body 125 and the ring with elastic return 131. Beyond this stroke 132, the intimate cooperation of said abutment body 125 and of said elastic return ring 131 generates traction on the cylindrical mandrel 136 reflected on the tubular axis 106 secured to the support 16 corresponding to the plate cylinder 9. Finally, it comes to fade with respect to the counterpressure cylinder 10 by performing a stroke 97 equivalent to the play existing between the elastic return ring 96 and the shoulder 104 defined in the stop body 90 of the stop means 88.

In contrast, the injection of laminating fluid into the chamber 42 of the cylinder 37 causes the ink cylinder 11 to return to the printing position on the one hand with respect to the plate cylinder 9, then of the latter with respect to the printing cylinder. back pressure 10, position corresponding to the abutment of the elastic return rings 96 and 131 against the internal face 101 and 134 of the retaining rings, respectively, 95 and 130.

Advantageously, such mechanical storage means 87 of the printing position of the different cylinders 9 to 11 between them can also constitute the mechanical connection to which reference was made above in the description and making it possible to control the movement. , both of the support 16 of the plate cylinder 9 and of the support 25 corresponding to the ink cylinder 11, by means of single motor means.

To this end, the cylindrical mandrel 136 is provided, at its free end 142, with a peripheral rim 143 against which the abutment body 125 comes to bear in the event of a command to release the ink cylinder 11, causing, simultaneously, the drive of the support 16, therefore the recoil of the plate cylinder 9 with respect to the counterpressure cylinder 10.

Figures 7 and 8 illustrate a second embodiment of these mechanical storage means 87 of the printing position of the printing cylinders 9 and inkers 11 therebetween.

In fact, and just as before, said mechanical means 87 consist of stop means 160, 161 capable of limiting the amplitude of movement of the plate cylinder 9 with respect to the counterpressure cylinder 10 and of the ink cylinder 11 with respect to the plate cylinder 9 at the time of temporary printing out.

In fact, since the counterpressure cylinder 10 is stationary relative to the frame 2 of the flexographic printing machine, the stop means 160 are intended to limit the amplitude of the displacement of the plate cylinder 9 on this frame 2.

More specifically, said stop means 160 are constituted according to this second embodiment, by a stop 162 made integral with the front or rear wall 3, 4 of said frame 2 and lying substantially in the same vertical plane as the end 18 of the guide shaft 17. Furthermore, said abutment means 160 comprise a transmission rod 163 capable of ensuring the cooperation of the supports 16 of the plate cylinder 9 with said abutment 162 disposed on the frame 2.

In fact, said transmission rod 163 is made integral, at one of its ends 163 and by means of connection means 165, with said support 16 of the plate cylinder 9. As for the other end 166, this transmission rod 163, it has in its lateral edges 167 and 168 a recess 169, 170 defining a portion 171 of smaller width which fits into a groove 172 arranged in the stop 162.

Note that the length 173 of the recesses 169, 170, arranged in the lateral edges 167, 168 of said transmission rod 163, is determined slightly greater than the thickness 174 of the stop 162 so that said rod 163 and, by Consequently, the support 16 of the plate cylinder 9 is able to move relative to the stop 162 over a limited stroke 175 and, this, during the temporary printing out.

Obviously, and due to the variable printing formats, the connection between the transmission rod 163 and the support 16 of the plate cylinder 9 must not be immutable. Also, as a connecting means 165, it is recommended to produce, in the end 164 of the transmission rod 163, an oblong hole 176 which comes to be crossed by a fixing rod 177 made integral with said support 16 of the plate cylinder 9. Note that on this fixing rod 177, acts a jack 178 capable of causing the tightening and, ultimately, of immobilizing the transmission rod 163 relative to said support 16. The presence of a hydraulic circuit on the flexographic printing machine for controlling the movement of the different cylinders 9 and 11 also justifies the use of this jack 178 at the level of the connecting means 165 connecting the support 16 of the plate cylinder 9 to said transmission rod 163.

It will be noted that during the various adjustments to the positioning of the plate cylinder 9, with respect to the counterpressure cylinder, this transmission rod 163 must be immobilized in translation relative to the stop 162 disposed on the frame 2 so that after tightening of the jack 178, it is ensured that this transmission rod 163 is correctly positioned relative to said stop 162 so as to allow movement, over a stroke 175, of the plate cylinder 9 with respect to the counterpressure cylinder 10.

For this purpose, elastic return means 179, constituted by helical springs inserted in blind holes arranged on the front face 180 of the stop 162 and coming to cooperate with the shoulders 181, 182 defined at the end 166 of the rod transmission 163, constantly pushes the latter forward relative to said stop 162.

As for the abutment means 161 capable of limiting the amplitude of the displacement of the ink cylinder 11 with respect to the plate cylinders 9, the latter assume a substantially symmetrical configuration with respect to a vertical median plane passing through the fixing rod 177.

Thus, said means 161 consist of a stop 185 disposed on a support 25 of the ink cylinder 11 and coming to cooperate with a transmission rod 186. More precisely, this comprises, at one of its ends 187 , an oblong slot 188 serving as a passage for the fixing rod 177, the other end 189A, of this transmission rod 186 having a narrower portion 189 defined by recesses 190, 191 arranged on the lateral edges 192, 193.

Again, said transmission rod 186 is able to move relative to the stop 185 according to a stroke 194 defined by the difference in length of the recesses 190, 191, arranged in said lateral edges 192, 193 and the thickness of the stop 185. Likewise, elastic return means 195, constituted by helical springs inserted in blind holes arranged on the rear face 196 of the stop 185 and coming to cooperate with the defined shoulders 197, 198, at the level of the end 189A of the transmission rod 186, maintain the latter in position offset towards the rear relative to said stop 185.

Thus, once the different cylinders 9, 10 and 11 are positioned relative to each other by means of the prepositioning devices 29, 30 or fine adjustment means 31, 32, the actuator 178 is actuated in order to make the transmission rods 163 and 186 of the support 16 of the plate cylinder 9.

Therefore, the control of the cylinder 37, by injection of laminating fluid into the chamber 43, causes, initially, the withdrawal of the support 25 from the plate cylinder 11 along a stroke 194 delimited by the play existing between the stop 185 and the shoulders 197, 198 arranged at the end 189A of the transmission rod 186.

Beyond this stroke 194, the intimate cooperation between said stop 185 and the transmission rod 186 generates traction on the support 16 of the plate cylinder 9, the latter coming to move on a stroke 175 corresponding to the games existing between the stop 162 and the shoulders 181, 182 defined at the end 166 of the transmission rod 163.

In contrast, the injection of the laminating fluid into the chamber 42 of the cylinder 37 causes the ink cylinder 11 to return to the printing position on the one hand relative to the plate cylinder 9 and then of the latter relative to the counterpressure cylinder. 10, position corresponding to the abutment of the shoulders 99, 200 and 201, 202 defined, respectively, at the level of the transmission rod 163 and of the transmission rod 186 with the rear face 203 respectively the front face 204 of the stop 162 disposed on the frame 2 and of the stop 185 secured to the support 25 of the ink cylinder 11.

Of course, as already mentioned above in the description, the structure of the printing unit 1 is strictly symmetrical relative to the longitudinal median plane of the strip to be printed and, therefore, we will find the mechanical storage means 86 as described above, both on the front wall 3 and on the rear wall 4 of the frame 2.

The present invention has the advantage of ensuring perfect reproducibility of the printing position, of the different cylinders with one another, in particular, in the event of temporary printing stopping of the strip support. In addition, it will be noted that, contrary to what has been done to date, this temporary printing stop command firstly generates the disengagement of the ink cylinder from the photographed cylinder and then the withdrawal of the latter from the band support maintained applied to the counterpressure cylinder. This results in the possibility of partially drying the printing cylinder on said strip support due to a prior interruption of the ink supply. Maintenance, cleaning and resumption of printing operations are thereby facilitated.

Claims (21)

1. Printing unit for flexographic printing machine with individual or single counterpressure cylinder (10) comprising, on the one hand, a plate cylinder (9), mounted movably, by means of supports (16), on the frame (2) of said flexographic printing machine, and an ink cylinder (11) combined with an inking device (12) and integral with supports (25) sliding on said frame (2) and, on the other hand , prepositioning devices (29, 30) and fine adjustment means (31, 32) for precisely positioning the different cylinders (9, 10, 11) with each other, printing unit characterized in that the supports (16, 25) arranged on one side of the longitudinal median plane of the strip support to be printed, the plate cylinder (9) and the ink cylinder (11) are slidably mounted, on the same guide shaft (17) integral with the frame (2), and are actuated by means of approach control and quick release (36) common to ensure the engagement or disengagement of the cylinders (9, 10, 11) therebetween. 2. Printing unit according to claim 1, characterized in that it comprises mechanical means (87) for on the one hand, memorizing the printing position of the plate cylinder (9) relative to the backpressure cylinder ( 10) and of the ink cylinder (11) with respect to said plate cylinder (9) and, on the other hand, limit the amplitude of the displacement of the cylinders (9 and 11) during the temporary printing out command. 3. Printing unit according to claim 1, characterized in that the approach and quick release control means (36) consist of a jack (37) whose body (38) is of the movable and formed type by the support (25) of the ink cylinder (11) and whose piston (39) is fixedly mounted on the guide shaft (17). 4. Printing unit according to claim 3, characterized in that the support (25) comprises a cylindrical recess (40) traversed right through by the guide shaft (17) and of diameter (41) substantially greater to the latter, the piston (39) subdividing this cylindrical recess (40) into two chambers (42, 43) between which is carried a rolling fluid to ensure the bringing together of the different cylinders (9, 10, 11) between them or their clearance in the event of printing stoppage. 5. Printing unit according to claim 1, characterized in that the prepositioning devices (29, 30) consist of format shims (33, 34) interposed, on the one hand, between the support (16) of the plate cylinder (9) and a stop (35) disposed at the end (18) located on the side of the counterpressure cylinder (10) of the guide shaft (17) and, on the other hand, between said support ( 16) and the support (25) of the ink cylinder (11), the dimension of these format shims (33, 34) being determined as a function of the printing format. 6. Printing unit according to claims 1 and 5, characterized in that the fine adjustment means (31) of the plate cylinder (9) relative to the counterpressure cylinder (10) are constituted by the stop (35), adjustable in nature, mounted at the end (18) of the guide shaft (17), this stop (35) being formed by a cylindrical end piece (47) made integral with the frame (2) and having, on its outer periphery , a fine thread (48) cooperating with a tapping machined in the bore of a bushing (50) comprising, on its outer periphery (53) a toothing (54) acting on a pinion (55) mounted on a transmission shaft (57) driven in rotation using manual or automatic control means (58). 7. Printing unit according to claims 1 and 3, characterized in that the fine adjustment means (32) of the ink cylinder (11) relative to the plate cylinder (9) are formed by a cylindrical end piece (67) extending hat closure (44) closing the cylindrical recess (40) of the jack (37) at its end (45) oriented in the direction of the counterpressure cylinder (10), this cylindrical end piece (67) being provided, on its outer periphery, with '' a fine thread (68) cooperating with a thread (69) machined in the bore of a sleeve (70) comprising, on its outer periphery (73), a toothing (74) intended to cooperate with a pinion (75) integral with a drive shaft (77) mounted, free to rotate, in bearings (78, 79) attached to the support (25) of the ink cylinder (11), this drive shaft (77) being driven in rotation, using manual automatic control means (81). 8. Printing unit according to claim 2, characterized in that the mechanical means (87) for memorizing the printing stop position of the different cylinders (9 to 11), between them, are constituted by stop means (88, 89, 160, 161) limiting the amplitude of the displacements carried out by the plate cylinder (9) with respect to the counterpressure cylinder (10) and by the ink cylinder (11) with respect to said plate cylinder (9). 9. Printing unit according to claim 8, characterized in that the stop means (88) serving to identify the positioning of the plate cylinder (9) relative to the counterpressure cylinder (10) consist of a stop body (90) made integral with the frame (2) and disposed, substantially, in the same vertical alignment as the end (18) of the guide shaft (17), this abutment body (90) having a central bore (91 ) having a first recess (92) serving as a housing for the means (93) for limiting the movement of a support (16) of the plate cylinder (9) on the guide shaft (17) and a second recess (94), larger diameter, allowing the engagement of a retaining ring (95). 10. Printing unit according to claim 9, characterized in that the means (93) are formed by a ring elastic return (96) capable of moving axially inside the recess (92), over a predetermined stroke (97), this elastic return ring (96) being brought to cooperate with transmission means (105) made integral , by means of connection means (107), of a support (16) of the plate cylinder (9) so as to limit the possible displacement of said support (16) to an amplitude equal to the stroke (97). 11. Printing unit according to claim 10, characterized in that the transmission means (105) comprise a tubular axis (106), parallel to the guide shaft (17) and made integral with the support (16), this tubular axis (106) being traversed by a shaft (108) cooperating, at one of its ends (109), with locking means (110) acting on the elastic return ring (96) and located in the extension axial of said tubular axis (106), this shaft (108) further comprising at its opposite end (111) manual or motorized rotation drive means (112). 12. Printing unit according to claim 11, characterized in that the locking means (110) are in the form of a cylindrical mandrel (113), split lengthwise, so as to accommodate expandable jaws (114 ) capable of cooperating with the internal bore (115) of the elastic return ring (96), these expandable jaws (114) being actuated, at their internal part (116) to the cylindrical mandrel (113), by the intermediate a wedge-shaped locking member (117) subjected to an axial displacement and comprising, in its center, a threaded orifice in which is screwed a threaded end piece (119) located in the axial extension and at the end ( 109) of the tree (108). 13. Printing unit according to claims 8, 10 and 11, characterized in that the stop means (89) are the symmetrical of the stop means (88) relative to a plane vertical median (124) passing through the connection means (107) connecting the transmission means (105) to the support (16) of the plate cylinder (9), these stop means (89) being inserted between the drive means in manual or motorized rotation (116) and the end (111) of the shaft (108) housed in the tubular axis (106). 14. Printing unit according to claim 13, characterized in that the stop means (89) consist of a stop body (125) made integral with a support (25) of the ink cylinder (11) and comprising , a central bore (126) in which a first recess (127) is produced serving as a housing for means (128) capable of limiting the displacement of the ink cylinder (11) relative to the plate cylinder (9) and a second recess ( 129) receiving a retaining ring (130). 15. Printing unit according to claim 14, characterized in that the means (128) consist of an elastic return ring (131), movable in translation, following a stroke (132), in the recess (127) and capable of cooperating with blocking means (135) associated with the transmission means (105) to limit the mobility of the support (25) relative to the support (16) of the plate cylinder (9) at a stroke equal to the stroke ( 132) of said elastic return ring (131). 16. Printing unit according to claim 15, characterized in that the locking means (135) are in the form of a cylindrical mandrel (136) split in its length so as to accommodate expandable jaws (137) capable to cooperate with the internal bore of the elastic return ring (131), these expandable jaws being actuated, at their internal part of the cylindrical mandrel (136), by means of a wedge-shaped member (138 ) provided with a threaded bore (139) through which a threaded end piece (140) extends the shaft (108) at its end (111), this threaded end piece being provided, at its free end (141), manual or motorized rotation drive means (112). 17. Printing unit according to claim 8, characterized in that the stop means (160) consist, on the one hand, of a stop (162) made integral with the front or rear wall (3, 4) of the frame (2) and lying substantially in the same vertical plane as the end (18) of the guide shaft (17) and, on the other hand, by a transmission rod (163) made integral, at level of one of its ends (164) and by means of connection means (165) of a support (16) of the plate cylinder (9), the other end (166) of this transmission rod ( 163) having in its lateral edges (167, 168) a recess (169, 170) defining a portion (171) of smaller width inscribed in a groove (172), arranged in the stop (162), the length (173 ) of these recesses (169, 170) being determined slightly greater than the thickness (174) of the stop (162) so that said support (16) of the plate cylinder (9) is able to move relative to the stop (162) over a limited stroke (175) during the temporary printing out. 18. Printing unit according to claim 17, characterized in that the transmission rod (163) comprises, at its end (164), an oblong lumen (176) crossed by a fixing rod (177) rendered integral with the support (16) of the plate cylinder (9) and cooperating with a jack (178) to immobilize in translation the transmission rod (163) relative to said support (16), the fixing rod (177) and the jack ( 178) constituting the connecting means (165). 19. Printing unit according to claim 17, characterized in that the abutment means (160) comprise elastic return means (179), constituted by helical springs inserted in blind holes arranged on the front face (180) from the stop (162) and coming to cooperate with shoulders (181, 182) defined at the end (166) of the transmission rod (163), to push the latter forward relative to said stop (162). 20. Printing unit according to claims 8 and 18, characterized in that the stop means (161) consist, on the one hand, of a stop (185) disposed on a support (25) of the ink cylinder (11 ) and, on the other hand, by a transmission rod (186) comprising, at one of its ends (187), an oblong opening (188) serving as a passage for the fixing rod (177) linked to the support (16) of the plate cylinder (9), the other end (189A) of this transmission rod (186) having a narrower portion (189) defined by recesses (190, 191) arranged on its lateral edges ( 192, 193) and having a length substantially greater than the thickness of the stop (185) so that the support (25) of the ink cylinder (11) is able to move, relative to the transmission rod (186 ) therefore with respect to the support (16) of the plate cylinder (9), over a stroke (194) limited when the time printing is out ire. 21. Printing unit according to claim 20, characterized in that the abutment means (161) comprising elastic return means (195), constituted by helical springs inserted in blind holes arranged on the rear face (196) of the stop (185) and coming to cooperate with defined shoulders (197, 198), by means of the recesses (190, 191) at the end (189A) of the transmission rod (186) to push back the latter backwards with respect to said stop (185).

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