EP0357530A1 - Frame for a flexographic printing machine - Google Patents

Abstract

A frame for a flexographic printing machine with an individual counterpressure cylinder (9 to 14) and comprising one or more printing units is made modular, each module (16 to 19, 69 and 70) ensuring the support and retention of a printing unit and its associated counterpressure cylinder. These modules are of a superposable type and comprise, in combination: - means (30) ensuring their positioning relative to one another, - connection means (40) for fixing them to one another, - and means (71) making it possible to stagger them in a horizontal direction to allow the partial winding of the carrier to be printed (15) round the counterpressure cylinder (9 to 14) of each of the printing units. <IMAGE>

Description

The invention relates to a frame for a flexographic printing machine with an individual counterpressure cylinder and comprising one or more printing units.

The invention will find its application, both with manufacturers and users of printing devices and, in particular, machines of the flexographic type.

The flexographic printing process, which is particularly known, consists of printing on strip supports such as paper, cellulose film, aluminum, plastics, etc. These prints are produced, more precisely, by passing the strip between a counterpressure cylinder and a plate cylinder, the latter transferring the graphics to be printed on the support. An ink cylinder receives an ink dosage from either a bubbling cylinder immersed in a basin containing ink, or by any other device, and ensures the transfer of ink onto the plate cylinder. The combination of these different cylinders constitutes a printing group.

The number of these printing groups, grouped together in a flexographic printing machine, will depend on the number of basic colors constituting the printing. So there are so-called two-color, four-color or six-color machines. When printing requires a higher number of colors, it is common to combine several flexographic printing units or machines.

Among the latter, there are also those which are said to have a single pressure cylinder around which the various inking stations are arranged and those which are said to have an individual pressure cylinder.

The present invention relates, more particularly, to flexographic printing machines of the second type and comprising, for each printing unit, a counterpressure cylinder.

Thus, the current design of these flexographic machines with individual counterpressure cylinders consists of a frame formed by two parallel walls arranged on either side of a vertical plane passing through the longitudinal axis of the strip forming the support to be printed. These walls are kept assembled by means of crossmembers distributed over the entire height of the frame. Furthermore, their size and their design depend on the number of printing units. Thus, this number is definitively determined at the time of the design of the flexographic printing machine.

On this frame are fixed, horizontally, the different counterpressure cylinders and implanted the drive mechanisms of the latter. In addition, the front and rear walls forming said frame are provided with bearings serving to accommodate a whole series of tape return rollers making it possible to orient the latter through the machine during printing.

The locations for printing units are drawn on the frame to the right of each counterpressure cylinder. Such locations may consist of slides arranged on each of the front and rear walls, slides on which is mounted, sliding, a support with which the plate cylinder is associated. The inking device composed of the inking cylinder and the bubbling cylinder is, according to this same particular embodiment, secured to a second support which is itself mounted free in translation on the support of the plate cylinder.

Of course, the shape of these locations will depend on the particular design of the printing units and the aforementioned slides can be replaced by different support means.

The disadvantages of these flexographic printing machines consist essentially of their rigid design, the origin of their reduced application under given printing conditions.

For example, a four-color machine is made up of four printing groups, it thus allows printing in four different shades or printing a double-sided tape requiring four applications.

Performed using such a machine, printing in two colors using only two printing units consists in reducing by half the profitability of this machine. This clearly results in higher manufacturing costs. Indeed, whatever the type of printing chosen, the cost of use is identical and it turns out to be preferable to use the flexographic printing machine in all its capacity.

By taking into account, only, this reasoning, a printing unit would be equipped with means of production largely superior to its workload or would present such rigidity, as for the diversity of the designed products, that it could not systematically adapt to market demand. It is therefore necessary to find an economic compromise which rarely corresponds to the minimum production cost.

Furthermore, from the manufacturer's point of view, this diversity existing in flexographic printing machines, does not allow them, unless they have a large and expensive stock, to meet immediate demand. Indeed, a six-color flexographic printing machine cannot suit a buyer of a flexographic printing machine which is limited to two or four printing groups.

These difficulties are also encountered in other printing processes than flexography and, for example, in offset printing systems. However, in this case, certain solutions have been proposed to remedy the aforementioned problems.

Thus, document US-A-2,479,023 discloses a frame for a printing machine, of the offset type, which is in modular form. More specifically, each module comprises a printing group and has, both in its front and rear part, assembly and positioning means allowing its association with other modules. This characteristic requires, however, the online arrangement of the various modules, resulting in a not insignificant size of the printing machine thus designed. In all cases, this cannot be adapted to a flexographic printing group.

In fact, the present invention aims to remedy the aforementioned drawbacks. The invention, as characterized in the claims, solves the problem of creating a frame for a flexographic printing machine with individual counterpressure cylinder and comprising one or more printing units, this frame being modular each module. comprising two parallel walls made integral by means of crosspieces and ensuring the support and the maintenance of a printing unit and its associated back-pressure cylinder, the various modules being, by the way, superimposable and comprising, in combination:
- means ensuring their positioning in relation to each other
- connecting means to make them united
- And means for shifting them in a horizontal direction to allow the partial winding of the support to be printed around the backpressure cylinders of each of the printing units.

The advantages obtained thanks to this invention consist, essentially, in that a flexographic printing machine comprising such a modular frame allows the suppression or the addition of printing groups according to the nature of the printing to be carried out or of the customer request. This machine thus acquires great adaptability to the most diverse manufacturing programs and this, at the always optimized production cost. In addition, it will be noted that the possibility, on the one hand, of superimposing the different modules and, on the other hand, of shifting them relative to each other, contributes to reducing the overall size of the flexographic printing machine without this posing any problem in terms of the passage of the support to be printed in said machine. In this regard, it should indeed be taken into consideration that such a support to be printed must, necessarily, be wound partially, around each of the backpressure cylinders of the different printing groups without it being possible to resume the orientation of this support by means of a deflection roller and at its freshly printed side.

• - la figure 1 représente, schématiquement et en élévation, une machine d'impression flexographique conforme à l'invention et comportant quatre groupes d'impression ;
• - la figure 2 représente une vue identique à la figure 1, la machine d'impression flexographique étant munie dans ce cas de six groupes d'impression ;
• - la figure 3 représente une vue en détail d'un mode de réalisation des moyens de positionnement d'un module du bâti par rapport à un autre ;
• - la figure 4 représente une vue agrandie de la partie notée à des figures 1 et 2 et représentant la liaison entre deux modules composant le bâti de la machine d'impression flexographique.

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

• - Figure 1 shows, schematically and in elevation, a flexographic printing machine according to the invention and comprising four printing groups;
• - Figure 2 shows a view identical to Figure 1, the flexographic printing machine being provided in this case with six printing units;
• - Figure 3 shows a detailed view of an embodiment of the positioning means of a module of the frame relative to another;
• - Figure 4 shows an enlarged view of the part noted in Figures 1 and 2 and showing the connection between two modules making up the frame of the flexographic printing machine.

It should be noted that the same reference in the different figures designates the same constituent element of the flexographic printing machine.

We refer to figure 1.

The present invention relates more particularly to the frame 1 of a flexographic printing machine 2 of the type with individual counterpressure cylinder. Thus, these printing machines comprise for each printing group 3, 4, 5, 6 (four in number in FIG. 1), a counterpressure cylinder 9, 10, 11, 12.

The number of these printing units is, of course, dependent on the number of printing layers to be transferred to the support 15 consisting of a strip for example, of paper, cellulose film, aluminum, plastics . Thus one can design flexographic printing machines with two, six or more printing groups.

Any flexographic printing machine consists of a frame 1 serving as a support for the various printing groups 3 to 6 and on which the counterpressure cylinders 9 to 12 are fixed. This frame 1 also contains motor and drive (not shown) capable of animating said backpressure cylinders 9 to 12 with a rotational movement during production.

However, the frame according to the invention has the particularity of being modular. To each couple; printing unit 3 to 6 and backpressure cylinders 9 to 12; corresponds to a module 16, 17, 18, 19, said to be basic because of their identity whatever their position in the flexographic printing machine.

More specifically, a basic module 16 to 19 consists of two walls 20 arranged parallel and symmetrically on either side of the longitudinal median plane of the strip 15. These walls 20 are made integral with one another by means of cross members 21, 22 , 23 the number and cross-section of which can be determined according to criteria of material resistance. Therefore, it has been recommended, according to the embodiment shown in FIGS. 1 and 2, to use a profile 21 of high mechanical strength (for example, of "U" or "I" section) to connect the walls 20 at the level of what constitutes, as described below, the location of a printing unit. This gives better transverse rigidity.

The addition of two additional crosspieces 22, 23 arranged at different heights, consolidates the whole. The crosspieces 22, 23, located on the side of the passage of the strip, will preferably be chosen, of round section so as not to damage said strip 15 when it is threaded into the flexographic printing machine 2.

Of course, other embodiments can be envisaged for connecting the walls 20 of a module 16 to 19.

These walls 20 also comprise a bearing 24 in which is mounted, free to rotate, one of the ends of the counterpressure cylinder 9 to 12. Other bearings can be fitted or provided in these walls 20, of a module 16 to 19, such bearings serving to hold strip return rollers 25, 26, orienting the latter through said module 16 to 19. Is also mounted on these walls 20 a pressure cylinder 27 pressed against the counterpressure cylinder 9 to 12 by pneumatic cylinders to drive the support to be printed on the first printing unit 3.

It should, in fact, be recalled that a printing group 3 to 6 consists, in all cases, of a cylinder plate 28 to 31 on which the plates which are to be printed on the support are reported. These plate cylinders 28 to 31 are of variable diameter, depending on the printing format and are arranged, parallel to the cylinders 9 to 12 pressure relief, so as to cooperate with them during printing. They are, moreover, mounted free in rotation on a support 32 movable in translation on the frame 1.

In addition, these printing units 3 to 6 comprise an ink cylinder 33, 34, 35, 36 generally screened, ensuring the transfer of ink, according to a dosage determined on the plate cylinder 28 to 31. This ink cylinder 33 to 36 is integral with a slide 37 capable of moving on the plate support 32 in a direction parallel to the movement of the latter on the frame 1.

Given that each module 16 to 19 of the frame 1 is associated with a printing group 3 to 6, their walls 20 comprise support means 38 for the latter. The design of these support means 38 will be more particularly adapted to that of the supports 32 of the plate cylinders 28 to 31. By way of example, mention will be made of the slides formed by a flat rectilinear and scraped surface on which the supports 32 can move. cited above.

The various modules 16 to 19 being brought to be superimposed on each other, they advantageously comprise, according to another characteristic of the invention, on the one hand, means 39 ensuring their positioning with respect to each other and connecting means 40 for making them integral.

According to a preferred embodiment, the positioning means 39 consist of a key 41 which is housed in a groove 42 machined on the upper edge 43 of the walls 20 of a module 16. This key 41 cooperates with a groove 44 arranged in the lower edge 45 of the walls 20 of a module 17 coming to be positioned immediately above. Thus, each wall 20 of a module 16 to 10 comprises, on its upper 43 and lower 45 edge, a groove with dimensions adjusted to those of the key 41.

This arrangement is more particularly visible in Figures 1 and 3.

In order to facilitate mounting and avoid a shift of the key 41 during assembly, the latter is fixed beforehand and by means of fixing members 46 such as a screw on the walls 20 of a module 17 to assemble.

According to the embodiment shown, said key 41 is positioned on the walls 20 in a direction perpendicular to the plane of the latter. It cannot, therefore, guarantee their positioning in a direction transverse to the longitudinal median plane of the support 15. For this purpose, there have been fitted, at the two ends 47, 48 of said key 41, tapped orifices 49, 50 in which are screwed with bolts 51, 52 provided with a washer 53, 54 coming to bear, respectively, on the internal face 55 and external 56 of the walls 20, both of the upper module 17 and of the lower 16. The tightening of these bolts 51, 52 causes, under the impulse of the washers 53, 54 the alignment of the superimposed walls 20 of the modules 16, 17 concerned.

As for the connecting means 40, these may be designed by any removable fixing member such as screws 57 inserted in orifices 58 machined in the lower edge 59 of openings 60, 61 arranged in the lower part 62 of the modules 17 Such screws 57 cooperate with threaded orifices 63 present in the upper edge 43 of the walls 20 of an associated module 16.

For considerations of threading the paper strip 15 or the like into the machine for double-sided printing, it is customary to design the frame 1 of said machine 2 for symmetrically with respect to a median plane transverse 64 to the longitudinal axis of said strip 15.

Thus, in order to facilitate the association of modules 16, 17 arranged on one side of said transverse median plane 64, with those 18, 19 situated on the opposite side, the frame 1, according to the invention comprises, on the one hand , a base 65 on which the lower modules 16, 18 are fixed. This base 65 rests on the ground and may, in certain cases, be part of a structure 66 external to the flexographic printing machine and ensuring the orientation of the support 15 in the latter. On the other hand, the frame 1 comprises a cap 67 which, like the base 65 can be integrated into the external structure 66 and ensures the connection of the upper modules 17, 19.

The positioning means 39 and the connecting means 40 involved in the cooperation of a lower module 16, 18 with the base 65 or of an upper module 17, 19 with the cap 67 may be identical to those mentioned above .

In this regard, it will be noted that the embodiment of these positioning means 39 and of these connecting means 40 described above is in no way limiting, other embodiments being conceivable.

By way of example, as positioning means 39, mention will be made of the pins which, arranged on the upper edge 43 of the walls 20 of a module 16 to 19 and cooperating with a bore arranged in the lower edge 45 of said walls 20 of a module 16 to 19 superimposed ensure perfect identification of these modules 16 to 19 between them.

FIG. 2 represents a flexographic printing machine 68 provided with a frame 1 provided with six modules 16 to 19, 69 and 70. This type of design requires the consideration of particular conditions of flexographic printing.

Indeed, it is important, to guarantee a good impression that the contact of the support 15 with a plate cylinder 28 to 31 is limited to a generator. However, by giving this support a path corresponding to the tangent to these plate cylinders 28 to 31, the contact is made on a sector and not on a generator due to the pressure exerted on the counterpressure cylinder 9 to 12 .

Therefore, it is necessary to ensure a partial winding of the strip 15 around each of said backpressure cylinders 9 to 12. Still, it is not necessary to obtain this partial winding by the addition of a cooperating intermediate return roller with the face of the strip 15 freshly printed.

In the case of a unit of two or four printing groups, the simplest solution consists in printing on the path of the strip 15, at the level of the entry and exit of a superposition of modules 16, 17, or 18, 19, a certain angle relative to the vertical so as to obtain the desired winding around the counterpressure cylinders 9 to 12.

The solution to the problem posed in the case of a machine 68 with six colors, advantageously consists in providing the modules 16 to 19, 69 and 70 with means 71 making it possible to offset them between themselves in a horizontal direction and, this, all retaining the positioning means 39 and connection 40 adopted for the designs with two or four inking stations.

These means 71 consist, on the one hand, in a particular arrangement of the grooves 42 and 44 machined in the upper edge 43, respectively, the lower edge 45 of the walls 20 of each of these modules 16 to 19, 69 and 70. More specifically, these grooves 42, 44 are formed at a reduced distance from the internal lateral edge 72 of said walls 20 corresponding distance, substantially, offset conferred on the different modules. More precisely, to solve the problem of winding the strip 15 around the counterpressure cylinder 9 to 14, while retaining the arrangement adopted within the framework of the four-color process, it is necessary to move the intermediate modules 17, 19 further apart. of the transverse median plane 64 relative to the other modules 16, 69, and 18, 70.

Due to the proximity of the grooves 42, 44 of the rear lateral edge 72 of the walls 20, the intermediate module 17, 19 is positioned, relative to the lower module 16, 18 and upper 69, 70 by cooperation of said rear lateral edge 72 of this intermediate module 17, 19 with the keys 41 fixed, respectively, in the groove 42 present in the upper edge 43 of the walls 20 of the lower module 16, 18 and in the groove 44 machined in the lower edge 45 of the walls 20 of the upper module 69 , 70.

It is under these conditions that the option of fixing the keys 41 on their respective module by means of fixing members 46 really finds its interest.

Another, more expensive solution, consists in multiplying the number of grooves 42, 44 in the different walls 20, the distance between these grooves 42, 44 corresponding, substantially to the amplitude of the offsets printed on the modules.

The means 71 are completed by the production of additional orifices 75, 76 in the lower edge 59 of the openings 60, 61 made in the lower part 62 of the walls 20. These orifices 75, 76 are used for the passage of screws 57 and respect a gap relative to the central orifice 58 corresponding to the aforementioned offset so that said screw 57 is able to cooperate with the same threaded orifice 63 present in the upper edge 43 of the walls 20 whatever the position of the modules 16, 17, 69 or 18, 19, 70 between them.

The advantages obtained thanks to this invention consist, mainly, in a standardization of the flexographic printing material thanks to a modular design.

Claims (9)

1. Frame for flexographic printing machine with individual backpressure cylinder (9 to 14) and comprising one or more printing units, characterized in that it is modular, each module (16 to 19, 69 and 70) comprising two parallel walls (20) made integral by means of crosspieces 21, 22, 23) and ensuring the support the maintenance of a printing unit and its associated counterpressure cylinder, the various modules (16 to 19 , 69 and 70) being stackable and comprising in combination:
- Means (39) ensuring their positioning with respect to each other
- connecting means (40) to make them integral
- And means (71) for shifting them in a horizontal direction to allow the partial winding of the support to be printed around the backpressure cylinder (9 to 14) of each of the printing units. 2. Frame according to claim 1, characterized in that the means (39) for positioning, between them, the modules (16, 17, 69) and (18, 19, 70) superimposed consist of a key (41 ) being received in a groove (42) machined on the upper edge (43) of the walls (20) of a module and cooperating with a groove (44) in the lower edge (45) of the walls (20) of a module coming to position immediately above. 3. Frame according to claim 2, characterized in that each of the walls (20) of a module (16 to 19, 69 and 70) comprises, in its upper edge (43) and in its lower edge (45) at at least one groove, respectively (42), (44) serving for the engagement of a key (41). 4. Frame according to claim 2, characterized in that the keys (41) are positioned in the grooves (42, 44) of the walls (20) in a direction perpendicular to the plane of the latter and comprise, at their ends (47 , 48), tapped holes (49, 50) into which are bolted bolts (51, 52) provided with a washer (53, 54) coming to bear, respectively, on the internal (55) and external (56 ) walls (20) of two superimposed modules to ensure their vertical alignment. 5. Frame according to claim 2, characterized in that the keys (41) are made integral with at least one module (16 to 19, 69 and 70) by means of a fixing member (46) such that a screw. 6. Frame according to claim 2, characterized in that the connecting means (40) are constituted by removable fixing members, such as screws (57), inserted in orifices (58) machined in the lower edge ( 59) of openings (60, 61) arranged in the lower part (62) of the modules (16, 19, 69 and 70), these removable fixing members cooperating with the walls (20) of a module placed immediately in below. 7. Frame according to claim 1, 2 and 6 characterized in that the means (71) for shifting the modules (16 to 19, 69 and 70) between them in a horizontal direction, consist, on the one hand, in arrange the grooves (42), (44), machined, respectively, in the upper (43) and lower (45) edge of the walls (20), near the internal lateral edge (72) of the latter and, on the other part, in the realization of orifices (75, 76) additional in the lower edge (59) of the openings (60, 61) made in the lower part (62) of the walls (20), these orifices (75, 76) serving the passage of the removable fasteners, and respecting a distance, relative to the central orifice (58) corresponding to the amplitude of the offset to be conferred between the modules (16 to 19, 69 and 70). 8. Frame according to claim 1, characterized in that it has a symmetrical structure with respect to the median plane (64), transverse to the longitudinal axis of the support to be printed (15), the superimposed modules (16, 17, 69) and (18, 19, 70) disposed, respectively, on either side of said transverse median plane (64) resting on a base (65) and being covered with a cap (67) the latter conferring unity on the frame 1. 9. Frame according to claim 1, characterized in that the crosspieces (22, 23) located on the side of the passage of the printing support (15) are of round section, the crosspiece (21) associating the walls (20) of a module (16 to 19, 69 and 70) at the printing unit (3 to 8) being of increased resistance to ensure transverse rigidity.

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