ARTICLES

Technical Field

The present invention relates to a digital printer for the decoration of manufactured articles.

Background Art

It is well known that in many industries, there is a special need to decorate manufactured articles, such as e.g. slab-shaped manufactured articles, by means of digital printing.

In this regard, in the context of this disclosure, the term “slab-shaped manufactured articles” means any product of flattened conformation having two dimensions of spatial extent (i.e., width and length) significantly larger than the third dimension (i.e., thickness), regardless of the material (rigid, soft or flexible) that makes it.

By way of example only and not as a limitation, tiles and slabs made of ceramic material, sheets of paper or cardboard and sheets of cloth are considered to be slabshaped manufactured articles that can be decorated by means of the present invention.

In the field of ceramic manufacturing, for example, there has always been the need to decorate the exposed face of the slab-shaped ceramic manufactured articles mainly for aesthetic purposes.

This practice is also related to the ceramic industries’ need to manufacture floor and wall tiles and slabs that are as different as possible from the competition and that best meet the required aesthetic standards of customers.

Specifically, the decoration of slab-shaped ceramic manufactured articles consists of applying pigments onto the exposed face of the tiles, made of unfired or partly fired ceramic material and then being fully and finally stabilized by firing in a kiln.

The decoration of the slab-shaped ceramic manufactured articles can be done by various methods, and currently, the use of digital printers is very widespread.

The decoration of the slab-shaped ceramic manufactured articles through digital printers involves the application of special ceramic inks, which consist of mixtures of powdered dyes (mineral oxides, or metal oxides, or metals characterized by complex structures), with a very fine grain size, suspended in a special solvent or other carrier. Digital printers for the decoration of tiles made of ceramic material of known type usually comprise a plane of forward movement on which the ceramic manufactured articles to be decorated move forward and a plurality of print heads facing the plane of forward movement and provided with nozzles dispensing the ceramic ink onto the exposed face of the ceramic manufactured articles.

The plane of forward movement usually consists of a conveyor belt which is moved along a substantially horizontal direction thanks to motor-driven pulleys or rollers.

In this way, the slab-shaped ceramic manufactured articles are moved below the print heads during ceramic ink dispensing.

The print heads spray ceramic ink onto the exposed face of the slab-shaped ceramic manufactured articles according to a previously established design.

The print heads are mounted above the plane of forward movement in a fixed position so as to cover the entire width of the plane of forward movement and to be able to decorate slab-shaped ceramic manufactured articles of any size, according to an operational mode commonly referred to as “single pass”.

Conventional digital printers do, however, have some drawbacks, including the fact that routine and extraordinary maintenance jobs are particularly difficult to carry out. The print heads are, in fact, usually mounted on a holding bar arranged above the plane of forward movement at a distance of a few centimeters from the plane itself.

Thus, the space to carry out any head replacement operations is very little and also involves a considerable complication in performing capping operations, i.e., covering unused heads with a coating cap intended to prevent the nozzles from drying out.

In this regard, it should be noted that head replacement and/or capping operations are quite frequent, not only to adjust or to clean any malfunctioning heads but also to change the printing area (i.e., the number and arrangement of the print heads), which may vary depending on the size of the slab- shaped ceramic manufactured articles to be decorated.

This means, therefore, that every time the tile format changes in production, it may be necessary to operate on the heads.

To remedy at least some of these issues, some digital printers provide for all print heads to be mounted on a sliding drawer; when maintenance/capping operations need to be carried out, the drawer is pulled out of the machine taking the print heads with it, allowing these to be replaced and/or cleaned and/or capped more easily.

Again, however, conventional digital printers suffer from serious drawbacks, among which it is possible to mention that maintenance/capping operations inevitably lead to the shutdown of the printer and, therefore, of the entire manufacturing plant of the slab- shaped ceramic manufactured articles, resulting in higher overall manufacturing costs.

In addition, the increase in manufacturing costs inevitably affects the retail price with the risk of making products less attractive to customers.

Similar problems for printing on slab-shaped manufactured articles are also present in sectors other than ceramic manufacturing, such as e.g. in the paper and cardboard printing sector or the cloth and fabric printing sector, as well as on manufactured articles which are not necessarily slab-shaped.

To solve at least part of the above drawbacks, the use of digital printers made in accordance with the teachings of patent application IT 102020000009508 is known.

That document describes a digital printer comprising a plurality of printing assemblies, each provided with a plurality of print heads, and a movement unit of the printing assemblies which is arranged above the line of forward movement of the manufactured articles and defines a shaped closed-loop movement path.

Specifically, the movement unit comprises a linear magnetic motor device provided with movable sliders on which the printing assemblies are mounted, the latter being movable along the movement path in a sliding manner, individually and independently of each other.

Going into the details of the movement path, it should be specified that it comprises a first stretch, substantially rectilinear, along which the printing assemblies are positionable to dispense the ink on the manufactured articles, and a second stretch, also substantially rectilinear, wherein the print head capping operations can be carried out (e.g., by means of one or more capping stations arranged therein).

The movement path then comprises a third stretch and a fourth stretch that are curvilinear in shape and connected to the first stretch and to the fourth stretch.

In this regard, document IT 102020000009508 instructs to arrange along at least one of the third stretch or the fourth stretch a maintenance station in which one or more operators can perform maintenance jobs on the printing assemblies.

Ultimately, the teachings contained in the application IT102020000009508 clearly allow obtaining a digital printer that can make it easier to perform maintenance and/or capping operations of the print heads than the previously described prior art.

In fact, it is easy to appreciate how it is sufficient to operate the linear magnetic motor device when needed to move the printing assemblies along the movement path and to arrange them, e.g., in one of either the capping station or the maintenance station.

Nevertheless, document IT102020000009508 is still amenable to refinement, especially aimed at further improving its convenience and efficiency of use.

First of all, it should be highlighted that the linear magnetic motor device allows the printing assemblies to be positioned very accurately if they are moved along rectilinear stretches, while it proves to be rather inaccurate if the same have to pass through one or more curvilinear stretches.

In other words, the use of a linear magnetic motor device can result in misplacements of the printing assemblies along the movement path if the latter are made to slide on curvilinear stretches.

It is easy to appreciate how the misplacement of the printing assemblies can result in the execution of decorations of disappointing and unsatisfactory quality on the manufactured articles and thus force the latter to be discarded, causing, as a direct consequence, considerable economic damage.

In addition, it is important to consider that the sliding of the printing assemblies along the movement path involves that the sliders on which they are mounted are provided both with roller-type bearings (which are known to be particularly adapted to move along rectilinear stretches) and with ball-type bearings (which are known to be particularly adapted to move along curved stretches).

However, such a solution is quite complex to implement and imposes rather high design and implementation costs, which inevitably affect the retail price of the decorated manufactured articles, risking reducing the consumers’ interest in their purchase.

Description of the Invention

The main aim of the present invention is to devise a digital printer for the decoration of manufactured articles which allows the print heads to be precisely and accurately positioned along the movement path, regardless of the conformation of the latter, thus making valuable and accurate decorations of the manufactured articles.

The object of the present invention is to devise a digital printer for the decoration of manufactured articles which allows for even more practical, easy and functional capping and/or maintenance operations of the print heads than the prior art mentioned above.

A further object of the present invention is to devise a digital printer for the decoration of manufactured articles which allows lowering production costs and the retail price of the finished products compared to the prior art mentioned above.

Another object of the present invention is to devise a digital printer for the decoration of manufactured articles that can overcome the aforementioned drawbacks of the prior art within the framework of a simple, rational, easy and efficient to use as well as cost- effective solution.

The aforementioned objects are achieved by this digital printer for the decoration of manufactured articles having the characteristics of claim 1.

Brief Description of the Drawings

Other characteristics and advantages of the present invention will become more apparent from the description of a preferred, but not exclusive, embodiment of a digital printer for the decoration of manufactured articles, illustrated by way of an indicative, yet non-limiting example, in the attached tables of drawings wherein:

Figure 1 is an axonometric view of a first embodiment of the printer according to the invention;

Figure 2 is a side view of the printer according to the invention;

Figures 3, 4 and 5 are axonometric views, on an enlarged scale, of a detail of the printer according to the invention in different configurations;

Figure 6 is an axonometric view of a second embodiment of the printer according to the invention;

Figure 7 is an axonometric view, on an enlarged scale, of a detail of the printer in accordance with the second embodiment;

Figure 8 is a plan view of a detail of the printer according to the invention, operating according to a first mode of operation;

Figure 9 is a plan view of a detail of the printer according to the invention, operating according to a second mode of operation.

Embodiments of the Invention

With particular reference to these figures, reference numeral 1 globally denotes a digital printer for the decoration of manufactured articles.

The digital printer 1 is, e.g., configured to decorate shaped manufactured articles M with slab-shaped conformation (e.g., ceramic tiles) and large formats (e.g., with sides longer than 2 m), but it can also be used to process manufactured articles with smaller formats and/or non-slab-shaped conformation.

The digital printer 1 comprises at least one base frame 2, for resting onto the ground, with which at least one line of forward movement 3 of the manufactured articles M is associated.

The line of forward movement 3 is adapted to move the manufactured articles M along a direction of forward movement A.

In detail, the line of forward movement 3 comprises at least one entry zone 3 a in which the manufactured articles M to be decorated are arranged and at least one exit zone 3b, opposite the entry zone 3a and arranged subsequently to the latter along the direction of forward movement A, wherein the already decorated manufactured articles M slide.

Advantageously, the line of forward movement 3 defines a substantially horizontal plane of forward movement on which the manufactured articles M rest by moving forward from the entry zone 3 a to the exit zone 3b along the direction of forward movement A.

In this case, the line of forward movement 3 is also substantially horizontal.

In more detail, the line of forward movement 3 consists e.g. of a conveyor belt.

The digital printer 1 comprises at least one supporting assembly 4 associated with the base frame 2 in a manner which is liftable and lowerable with respect to the line of forward movement 3.

For this purpose, the base frame 2 comprises a pair of vertical uprights 5 along which the supporting assembly 4 is engaged in a sliding manner.

Conveniently, the digital printer 1 comprises automatic fine-tuning means, not shown in detail in the figures, which adjust the lifting and lowering of the supporting assembly 4 depending on the thickness of the manufactured articles M.

In actual facts, for the decoration of particularly thin manufactured articles M (e.g., with thickness equal to 4 mm), the supporting assembly 4 is located in the proximity of the line of forward movement 3; however, for the decoration of thick manufactured articles M (e.g., with thickness equal to 2 cm), the supporting assembly 4 is located at a greater distance from the line of forward movement 3.

Automatic fine-tuning means consist, e..g., of a micrometer-controlled electric motor or other related system.

The supporting assembly 4 is associated with at least one movement unit 6 arranged at least partly above the line of forward movement 3 and defining a movement path Pl, P2, P3, P4.

In detail, the movement path Pl, P2, P3, P4 extends along at least a first stretch Pl and at least a second stretch P2 which are substantially rectilinear in shape.

The first stretch Pl and the second stretch P2 are both arranged above the line of forward movement 3. Precisely, the first stretch Pl and the second stretch P2 are rectilinear and parallel to each other.

In particular, the first stretch Pl and the second stretch P2 have substantially the same length.

Again, the first stretch Pl and the second stretch P2 are arranged transversely to the direction of forward movement A.

In the present case, the first stretch Pl and the second stretch P2 are arranged orthogonally to the direction of forward movement A.

In addition, the movement path Pl, P2, P3, P4 also extends along at least a third stretch P3 arranged to connect the first stretch Pl and the second stretch P2 to each other.

In this regard, to say that the third stretch P3 is arranged to connect the first stretch Pl and the second stretch P2 to each other is to mean that one extremity of the third stretch P3 is adjacent to one extremity of the first stretch Pl and the other extremity of the third stretch P3 is adjacent to one extremity of the second stretch P2.

In other words, the first stretch Pl, the second stretch P2 and the third stretch P3 make a path that is substantially free of discontinuities.

By detailing the third extremity P3 in more detail, it should first be specified that it is arranged so that it protrudes beyond the line of forward movement 3.

In addition, the third stretch P3 is preferably substantially rectilinear in shape.

In detail, the third stretch P3 is arranged transversely to the first stretch Pl and to the second stretch P2.

Specifically, as visible in Figure 1, the third stretch P3 is arranged orthogonally to the first stretch Pl and to the second stretch P2.

In this sense, the first stretch Pl, the second stretch P2 and the third stretch P3 are arranged in such a way as to make a movement path Pl, P2, P3, P4 which is substantially “U”-shaped.

However, embodiments of the third stretch P3 which are alternative to the one just described cannot be ruled out wherein, e.g., the third stretch P3 has a curvilinear conformation (e.g., a third stretch P3 in the shape of a “C”, in the shape of an “S” and so on).

A plurality of printing assemblies 7 is mounted on the movement unit 6, which assemblies are movable in a sliding manner along the movement path Pl, P2, P3, P4, individually and independently of each other, between at least one position of work, wherein the printing assemblies 7 are arranged above the line of forward movement 3 for the dispensing of ink onto the manufactured articles M, and at least one home position.

To be precise, the printing assemblies 7 are located where the first stretch Pl is positioned when they are in the position of work.

Specifically, in this position, the printing assemblies 7 face towards the exit zone 3b.

This means that the printing assemblies 7 in the position of work protrude outwardly from the movement unit 6 and face overhanging on the line of forward movement 3 facing a direction concordant with the direction of forward movement A.

Speaking of the position of work, it should be added that each of the printing assemblies 7 comprises a plurality of print heads 11 provided with nozzles 12 oriented along a printing direction B substantially orthogonal to the direction of forward movement A.

In fact, this first type of printing assemblies 7 allows the digital printer 1 to operate according to a first operational mode of the “single pass” type, shown in Figure 8, wherein a plurality of printing assemblies 7 is placed in the position of work, which assemblies are made according to the first type and intended to remain stationary during the passage of the manufactured articles M.

The number of printing assemblies 7 placed in the position of work depends on the size of the manufactured articles M, so that a printing area covering the entire extent of the manufactured articles M is defined.

In combination with, or as an alternative to, the first type of printing assemblies 7 just described, a second type may be provided wherein at least one of the printing assemblies 7 comprises a plurality of print heads 11 provided with nozzles 12 oriented along a printing direction C substantially parallel to the direction of forward movement A.

This second type of printing assemblies 7 allows the digital printer 1 to operate in accordance with a second operational mode of the “scanning” type, shown in Figure 9, wherein only one printing assembly 7 is placed in the position of work, which is made in accordance with the second type and intended to be moved back and forth along the movement unit 6 during the passage of the manufactured articles M.

By means of the first operational mode (“single pass”), faster prints can be achieved.

By means of the second operational mode (“scanning”), prints with higher resolution and image quality can be achieved. Regardless of the type and mode of operation, the nozzles 12 of the print heads 11 are electronically controlled to dispense ink only when and where it is needed.

Then, to describe the home position, it is good to say that it comprises at least one of either at least a capping station 13 or at least a maintenance station 14.

Preferably, the digital printer 1 comprises at least two home positions, wherein at least a first home position comprises a capping station 13 and at least a second home position comprises a maintenance station 14.

In the particular embodiment shown in the figures, the digital printer 1 comprises two home positions, of which a first home position which comprises a capping station 13 and a second home position which comprises a maintenance station 14.

Alternative embodiments of the present invention cannot however be ruled out wherein only one home position is present or three or more are present.

In the particular embodiment shown in the figures, the capping station 13 is arranged along the second stretch P2.

For example, the capping station 13 consists of a bedplate 15 mounted cantilevered on the supporting assembly 4 above the line of forward movement 3 and vertically movable together with the movement unit 6.

The bedplate 15 has a substantially horizontal conformation and defines a resting plane for the printing assemblies 7.

Since the nozzles 12 of the print heads 11 face downwards, when a printing assembly 7 rests on the bedplate 15, it automatically causes its nozzles 12 to close and prevents them from drying out.

On the other hand, the maintenance station 14 consists of an equipped site 16 associated with the base frame 2 wherein an operator O can perform maintenance jobs (e.g., on the print heads 11) when required.

With reference to the embodiment shown in the figures, the maintenance station 14 is arranged along the third stretch P3.

However, different placements of the capping station 13 and of the maintenance station 14 cannot be ruled out.

For example, alternative embodiments cannot be ruled out wherein the capping station 13 is arranged along the third stretch P3 and the maintenance station 14 is arranged along the second stretch P2.

Sticking to describing the preferred embodiment, the printing assemblies 7 are placed at the second stretch P2 when they are in the first home position and are placed at the third stretch P3 when they are in the second home position.

In particular, the printing assemblies 7 placed in the first home position face the entry zone 3 a.

In other words, the printing assemblies 7 in the first home position protrude outwardly from the movement unit 6 and face overhanging the line of forward movement 3 facing a discordant direction to the direction of forward movement A.

As for the second home position, on the other hand, the printing assemblies 7 thus positioned face a direction away from the entry zone 3a and from the exit zone 3b transverse to the direction of forward movement A.

Precisely, the printing assemblies 7 in the second home position protrude externally from the movement unit 6 and face overhanging the line of forward movement 3 facing an orthogonal direction to the direction of forward movement A.

Conveniently, the movement unit 6 comprises at least one of either a first linear magnetic motor device 8a arranged along the first stretch Pl and a second linear magnetic motor device 8b arranged along the second stretch P2.

Preferably, the movement unit 6 comprises both a first linear magnetic motor device 8a and a second linear magnetic motor device 8b.

Specifically, the first linear magnetic motor device 8a and the second linear magnetic motor device 8b are provided with a plurality of movable sliders 9 on which the printing assemblies 7 are mounted.

In actual facts, the first linear magnetic motor device 8a and the second linear magnetic motor device 8b consist of electric motors wherein the rotor and the stator, instead of being circular, are deployed along a linear direction and wherein, instead of generating a mechanical moment, they produce a force.

Specifically, the first linear magnetic motor device 8a enables the production of a magnetic field which is able to set the movable sliders 9 in motion along the first stretch Pl.

It is easy to appreciate, then, that it is sufficient to stop the magnetic field generated by the first linear magnetic motor device 8a to block the movable sliders 9 and thus the printing assemblies 7 mounted thereon, at the desired positions along the first stretch Pl.

As for the second linear magnetic motor device 8b, it enables the production of a magnetic field which is able to set the movable sliders 9 in motion along the second stretch P2. Similarly to what has been said for the first linear magnetic motor device 8a, it is sufficient to stop the magnetic field generated by the second linear magnetic motor device 8b to block the movable sliders 9 and thus the printing assemblies 7 mounted thereon, at the desired positions along the second stretch P2.

Preferably, the first linear magnetic motor device 8a is built into the first stretch Pl.

Similarly, the second linear magnetic motor device 8b is built into the second stretch P2.

The adjustment of the movement and of the blocking of the movable sliders 9 is done in a micrometric way, i.e., the first linear magnetic motor device 8a and the second linear magnetic motor device 8b place the movable sliders 9 and the printing assemblies 7 along the first stretch Pl and the second stretch P2, respectively, with great accuracy.

Conveniently, a printing assembly 7 is provided for each movable slider 9.

Specifically, the printing assemblies 7 are mounted overhanging with respect to the movable sliders 9 and have all nozzles 12 facing downwards.

Each movable slider 9 comprises lifting and lowering means 10 of a respective printing assembly 7.

In actual facts, each printing assembly 7 is individually liftable with respect to the movement unit 6.

The lifting and lowering means 10 consist, e.g., of a pneumatic actuator mounted on each movable slider 9 and associated with the respective printing assembly 7.

Each pneumatic actuator is adapted to displace the respective printing assembly 7 between two extreme positions, namely a lowered position and a lifted position.

In actual facts, when the printing assemblies 7 are placed in the position of work, the lifting and lowering means 10 are lowered to arrange the print heads 11 in the proximity of the line of forward movement 3 (e.g., a few mm away) and to improve the printing quality.

When, on the other hand, the printing assemblies 7 are placed in the capping station 13, then the lifting and lowering means 10 are lifted to allow the printing assemblies 7 to be raised above the elevation of the bedplate 15, then the printing assemblies 7 are displaced along the movement unit 6 to be placed above the bedplate 15, and finally the lifting and lowering means 10 are lowered to place the printing assemblies 7 on the bedplate 15.

This means that the bedplate 15 is placed at a higher elevation (i.e., at a distance away from the line of forward movement 3) than the elevation of the printing assemblies 7 when the latter are in the lowered position and at a lower elevation than the elevation of the printing assemblies 7 when the latter are in the lifting position.

It is also good to highlight that the lifting and lowering means 10 are quite useful where the equipped site 16 is located, as they allow the printing assemblies 7 to be located in the lifting position (e.g., at man height) and to facilitate the operations by the operator O.

According to the invention, the movement unit 6 comprises at least one transfer element 17a on which the printing assemblies 7 are positionable in a sliding manner.

Specifically, the transfer element 17a is movable along the third stretch P3 between at least a first transfer position, wherein it is aligned with the first stretch Pl, and at least a second transfer position, wherein it is aligned with the second stretch P2.

In this regard, to say that the transfer element 17a is aligned with the first stretch Pl is to mean that in the first transfer position its particular positioning allows the printing assemblies 7 to slide substantially without interruptions between the first stretch Pl and the transfer element itself.

In actual facts, in the first reference position, the transfer element 17a is positioned at the extremity of the third stretch P3 which is adjacent to the first stretch Pl as if to form an extension of the first stretch Pl on which the printing assemblies 7 are positionable in a sliding manner.

Similarly, to say that the transfer element 17a is aligned with the second stretch P2 is to mean that, in the second transfer position, its particular positioning allows the printing assemblies 7 to slide without interruptions between the second stretch P2 and the transfer element itself.

In actual facts, in the second reference position, the transfer element 17a is positioned at the extremity of the third stretch P3 which is adjacent to the second stretch P2 as if to form an extension of the second stretch P2 on which the printing assemblies 7 are positionable in a sliding manner.

To enable the movement of the printing assemblies 7 between the first stretch Pl and the second stretch P2, the movement unit 6 comprises movement means 18a which are associated with the base frame 2 and which are adapted to move the transfer element 17a between the first transfer position and the second transfer position.

It is therefore sufficient to place one or more printing assemblies 7 at the transfer element 17a and then operate the movement means 18a to move the transfer element itself and the printing assembly 7 positioned thereon between the first transfer position and the second transfer position.

In this way it is clearly possible to transfer one or more printing assemblies 7 between the first stretch Pl and the second stretch P2 quite smoothly.

It is worth noting, in this regard, that the aforementioned transfer occurs without any intervention by the first linear magnetic motor device 8 a and by the second linear magnetic motor device 8b.

This proves particularly useful in that it allows transferring and, therefore, positioning the printing assemblies 7 along the movement path Pl, P2, P3, P4 to be particularly accurate even if the third stretch P3 has a curvilinear shape.

In other words, this particular technical expedient enables the precise positioning of the printing assemblies 7 along the movement path Pl, P2, P3, P4 regardless of the conformation of the latter.

It is also important to consider that, being the maintenance station 14 arranged along the third stretch P3, the second home position is located between the first transfer position and the second transfer position.

This advantageously results in the possibility of using the movement means 18a and the transfer element 17a to place the printing assemblies 7 in the second home position.

Going into the details of the movement means 18a, they comprise at least one guide 19a developing along the third stretch P3 and at least one runner 20a which is shiftable along the guide 19a and is associated with the transfer element 17a.

The runner 20a comprises, in turn, at least one sliding portion 21a which is associated with the guide 19a in a sliding manner.

Via the sliding of the sliding portion 21a, it is, therefore, possible to move the runner 20a and, consequently, the transfer element 17a between the first transfer position and the second transfer position quite smoothly.

In addition, the runner 20a comprises at least one revolving portion 22a which is associated with the sliding portion 21a.

Specifically, the revolving portion 22a is rotatable around at least one substantially vertical axis of rotation R1 and is locked together in rotation with the transfer element 17a.

Providing a revolving portion 22a in combination with a sliding portion 21a turns out to be a particularly advantageous expedient for a number of reasons. First of all, as can be seen by comparing Figures 1, 3 and 4, it is possible to arrange the printing assembly 7 positioned on the transfer element 17a from the first transfer position to the second home position simply by making the sliding portion 21a slide along the guide 19a until the runner 20a is arranged where the maintenance station 14 is located and by rotating, at the same time, the revolving portion 22a around the axis of rotation R1 (e.g., by 90°).

Not only that, but by comparing Figure 3 and Figure 5 it is clear that providing a revolving portion 22a in combination with the sliding portion 21a also makes it possible to transfer the printing assemblies 7 between the first stretch Pl and the second stretch P2 by making sure that they always face outwardly from the movement unit 6 regardless of which stretch they are on.

It is sufficient, in fact, to make the sliding portion 21a slide between the first transfer position and the second transfer position and to rotate, at the same time, the revolving portion 22a around the axis of rotation R1 (e.g., by 180°), to turn the printing assembly 7 positioned on the transfer element 17a towards the entry zone 3a or towards the exit zone 3b depending on whether the same is arranged on the second stretch P2 or on the first stretch Pl, respectively.

Precisely, the revolving portion 22a rotates around the axis of rotation R1 by 180° in a clockwise direction switching from the first transfer position to the second transfer position.

In a completely mirroring manner, the revolving portion 22a rotates around the axis of rotation R1 by 180° in a counterclockwise direction switching from the second transfer position to the first transfer position.

In this sense, therefore, it is possible to obtain a movement unit 6 which allows the printing assemblies 7 to be transferred between the first stretch Pl and the second stretch P2 in an absolutely symmetrical manner; that is, allowing the printing assemblies 7 to turn towards opposite zones to each other when the same are placed on the first stretch Pl or on the second stretch P2.

Embodiments of the runner 20a different from the one just described cannot, however, be ruled out.

For example, alternative embodiments cannot be ruled out wherein the runner 20a is without the revolving portion 22a and thus comprises only the sliding portion 21a.

In this case, if a printing assembly 7 is transferred from the first stretch Pl to the second stretch P2 (i.e., the movement means 18a move the sliding element 17a from the first transfer position to the second transfer position), it remains facing the exit zone 3b.

It is important to note that in order to allow the transfer element 17a to be rotated around the axis of rotation Rl, it is necessary for the sliding portion 21a to slide on the guide 19a at least sufficiently to allow misalignment between the transfer element itself and the first stretch Pl (if the transfer element 17a is in the first transfer position) or the second stretch P2 (if the transfer element 17a is in the second transfer position).

In this way, in fact, it is possible to perform the rotation of the revolving portion 22a in a safe and proper manner, that is, without the transfer element 17a contacting/impacting, in doing so, against one of either the first stretch Pl or the second stretch P2.

It is, therefore, convenient to misalign the transfer element 17a from the first stretch Pl or from the second stretch P2 and, only then, to start rotating the revolving portion 22a around the axis of rotation Rl.

In particular, rotation can occur continuously and smoothly, that is, by causing the transfer element 17a and the printing assembly 7 positioned thereon to rotate progressively when transferring from one position to another.

For example, the transfer element 17a moved from the first transfer position to the second transfer position can be made to rotate around the axis of rotation Rl by 180° steadily, thus switching from an angle of rotation of 0° at the first transfer position to an angle of 180° at the second transfer position.

Alternatively, the rotation of the sliding portion 21a around the axis of rotation Rl can be carried out only once the transfer element 17a is placed at one of the first transfer position, the second transfer position or the second home position.

For example, it is possible to make the sliding portion 21a slide from the first transfer position to the second transfer position and to rotate the sliding portion 21a around the axis of rotation Rl (e.g., still by 180°) only once the transfer element 17a is positioned at the second stretch P2.

In either case, the first movement performed by the transfer element 17a with respect to one of either the first stretch Pl or the second stretch P2 is still a pure shifting movement along the guide 19a.

It is however possible to provide height adjustment means, not shown in the figures for simplicity sake, associated with the runner 20a and adapted to adjust the height of the transfer element 17a with respect to the movement path Pl, P2, P3, P4. Therefore, the height adjustment means may increase or decrease the elevation of the transfer element 17a, by making it, e.g., higher or lower than the elevation at which the movement path Pl, P2, P3, P4 has been positioned.

Thus, in this case, the height adjustment means can be operated to vertically misalign the transfer element 17a with respect to the first stretch Pl or to the second stretch P2 and, at that point, operate the sliding portion 21a in rotation around the axis of rotation Rl.

For example, the transfer element 17a can be moved from the first transfer position to the second transfer position by raising the elevation of the latter to a higher value than that of the movement path Pl, P2, P3, P4, by rotating it (e.g., by 180°) around the axis of rotation Rl, by operating the sliding portion 21a on the guide 19a in a sliding manner, and by reducing, at that point, the elevation of the transfer element 17a as far as it is vertically realigned with the movement path Pl, P2, P3, P4.

In this sense, the first movement carried out by the transfer element 17a with respect to the first stretch Pl and to the second stretch P2 is a pure vertical shifting movement.

Ultimately, according to the first embodiment described so far shown in Figure 1, the movement path Pl, P2, P3, P4 extends only on the first stretch Pl, on the second stretch P2 and on the third stretch P3.

In accordance with a second embodiment which is alternative to the previous one and shown in Figure 6, on the other hand, the movement path Pl, P2, P3, P4 also extends along at least a fourth stretch P4.

Specifically, the fourth stretch P4 is connected to the first stretch Pl and to the second stretch P2 to define a closed path.

This means that the fourth stretch P4 is arranged, similarly to what has been said above for the third stretch P3, to connect the first stretch Pl and the second stretch P2 to each other.

In this regard, to say that the fourth stretch P4 is arranged to connect the first stretch Pl and the second stretch P2 to each other is to mean that one extremity of the fourth stretch P4 is adjacent to one extremity of the first stretch Pl and the other extremity of the fourth stretch P4 is adjacent to one extremity of the second stretch P2.

Conveniently, in this second embodiment at least one of the third stretch P3 or the fourth stretch P4 is substantially rectilinear in shape.

Preferably, as visible in Figure 6, both the third stretch P3 and the fourth stretch P4 are substantially rectilinear in shape. In this case, the fourth stretch P4 is arranged substantially parallel to the third stretch P3.

This means that the fourth stretch P4 is arranged substantially orthogonal to the first stretch Pl and to the second stretch P2.

Again, the fourth stretch P4 and the third stretch P3 have substantially the same length. In actual facts, the first stretch Pl, the second stretch P2, the third stretch P3 and the fourth stretch P4 are mutually arranged so as to make a movement path Pl, P2, P3, P4 substantially rectangular in shape (in the event of the first stretch Pl and the second stretch P2 having equal length and different from that of the third stretch P3 and of the fourth stretch P4) or square in shape (in the event of the first stretch Pl, the second stretch P2, the third stretch P3 and the fourth stretch P4 all having substantially the same length).

It is specified that, in this second embodiment, the printing assemblies 7 can move along the movement path Pl, P2, P3, P4 either in one direction of travel or in the opposite direction.

This is quite advantageous in allowing the swapping of the printing assemblies 7 in the position of work.

Since, in fact, each printing assembly 7 is movable individually and independently of the others, it is possible to place in the position of work all and only those printing assemblies 7 needed to cover the printing area determined by the size of the manufactured articles M being processed.

In accordance with this second embodiment, the movement unit 6 comprises at least one auxiliary transfer element 17b on which the printing assemblies 7 can be positioned in a sliding manner.

Specifically, the auxiliary transfer element 17b is movable along the fourth stretch P4 between at least a first auxiliary transfer position, wherein it is aligned with the first stretch Pl, and at least a second auxiliary transfer position, wherein it is aligned with the second stretch P2.

In this regard, to say that the auxiliary transfer element 17b is aligned with the first stretch Pl is to mean that in the first auxiliary transfer position, its special positioning allows the printing assemblies 7 to slide substantially without interruptions between the first stretch Pl and the auxiliary transfer element itself.

In actual facts, in the first auxiliary reference position, the auxiliary transfer element 17b is positioned at the extremity of the fourth stretch P4 which is adjacent to the first stretch Pl as if to form an extension of the first stretch Pl on which the printing assemblies 7 can be positioned in a sliding manner.

Similarly, to say that the auxiliary transfer element 17b is aligned with the second stretch P2 is to mean that in the second auxiliary transfer position its special positioning allows the printing assemblies 7 to slide without interruptions between the second stretch P2 and the auxiliary transfer element itself.

In actual facts, in the second auxiliary reference position, the auxiliary transfer element 17b is placed at the extremity of the fourth stretch P4 which is adjacent to the second stretch P2 as if to form an extension of the second stretch P2 on which the printing assemblies 7 can be positioned in a sliding manner.

Having specified the use of such terminology, it is now clear to appreciate that in Figure 6, the transfer element 17a is in the first transfer position and the auxiliary transfer element 17b is in the first auxiliary transfer position.

The movement unit 6 comprises, in the second embodiment, auxiliary movement means 18b which are associated with the base frame 2 and are adapted to move the auxiliary transfer element 17b between the first auxiliary transfer position and the second auxiliary transfer position.

Therefore, it is sufficient to place a printing assembly 7 where the auxiliary transfer element 17b is located and then to operate the auxiliary movement means 18b to move the auxiliary transfer element 17b and the printing assembly 7 positioned thereon between the first auxiliary transfer position and the second auxiliary transfer position. Similar considerations about the benefits obtained through the use of the movement means 18a are to be considered equally valid with regard to the use of the auxiliary movement means 18b, so they are not set forth further.

Going into the details of the auxiliary movement means 18b, they comprise at least one auxiliary guide 19b developing along the fourth stretch P4 and at least one auxiliary runner 20b which is shiftable along the auxiliary guide 19b and is associated with the auxiliary transfer element 17b.

The auxiliary runner 20b also comprises at least one auxiliary sliding portion 21b which is associated with the auxiliary guide 19b in a sliding manner.

By means of the sliding of the auxiliary sliding portion 21b, it is therefore possible to move the auxiliary runner 20b and, therefore, the auxiliary transfer element 17b quite smoothly between the first auxiliary transfer position and the second auxiliary transfer position. In addition, the auxiliary runner 20b comprises at least one auxiliary revolving portion 22b which is associated with the auxiliary sliding portion 21b.

Specifically, the auxiliary revolving portion 22b is rotatable around at least one substantially vertical auxiliary axis of rotation R2 and is locked together in rotation with the auxiliary transfer element 17b.

The auxiliary axis of rotation R2 is, therefore, parallel to the axis of rotation Rl.

In particular, the auxiliary revolving portion 22b operates quite similarly to the revolving portion 22a and thus enables the same technical advantages to be obtained in combination with the auxiliary sliding portion 21b as previously outlined and to the detailed description of which one is referred.

It is possible, in this regard, to provide auxiliary height adjustment means, not shown in the figures for simplicity sake, associated with the auxiliary runner 20a and adapted to adjust the height of the auxiliary transfer element 17b with respect to the movement unit 6.

The auxiliary height adjustment means can therefore increase and decrease the elevation of the auxiliary transfer element 17b in much the same way as through the use of the height adjustment means on the transfer element 17a.

An application example for transferring the printing assemblies 7 from the first stretch Pl to the second stretch P2 is given below.

To do this, simply make the printing assembly 7 slide along the first stretch Pl by operating the first linear magnetic motor device 8a as far as it is positioned at either the transfer element 17a or the auxiliary transfer element 17b.

In the first case, it is sufficient to operate the movement means 18a to transfer the transfer element 17a from the first transfer position to the second transfer position.

Once this is done, the printing assembly 7 can be moved with respect to the transfer element 17a by means of the operation of the second linear magnetic motor device 8b and can, in this way, be positioned by sliding on the second stretch P2.

In the second case, however, it is sufficient to operate the auxiliary movement means 18b to transfer the auxiliary transfer element 17b from the first auxiliary transfer position to the second auxiliary transfer position.

Once this is done, the printing assembly 7 can be moved with respect to the auxiliary transfer element 17b by means of the operation of the second linear magnetic motor device 8b and can, in this way, be positioned by sliding on the second stretch P2.

Taking the above into consideration, it is clear at this point to appreciate that the auxiliary transfer element 17b and the auxiliary movement means 18b are completely identical, both functionally and structurally, to the transfer element 17a and to the movement means 18a respectively.

This particular expedient clearly makes it possible to create a perfectly symmetrical movement unit 6, thus reducing the manufacturing costs thereof and greatly simplifying, at the same time, the installation and functionality thereof.

It has in practice been ascertained that the described invention achieves the intended objects.

In particular, the fact is emphasized that the special expedient of providing a transfer element of the printing assemblies which can be aligned with the first stretch and with the second stretch and movement means of the transfer element enables precise and accurate positioning of the printing assemblies along the movement path regardless of the conformation of the latter.

In fact, it is possible to use the first linear magnetic motor device and the second linear magnetic motor device to move the printing assemblies along the first stretch and the second stretch, respectively and to use the movement means to enable the transfer of the printing assemblies between the first stretch and the second stretch instead.

Finally, the special expedient of providing an auxiliary transfer element and relevant auxiliary movement means makes it possible to make a perfectly symmetrical movement guide which, by defining a closed movement path, allows for completely smooth and efficient movement and swapping of the printing assemblies.