WO2017068459A1

WO2017068459A1 - Digital printer for rigid supports

Info

Publication number: WO2017068459A1
Application number: PCT/IB2016/056078
Authority: WO
Inventors: Matteo COPPELLI
Original assignee: Sertile S.R.L.
Priority date: 2015-10-19
Filing date: 2016-10-11
Publication date: 2017-04-27
Also published as: ES2685672T3; ITUB20155130A1; EP3365179B1; ES2685672T1; EP3365179A1

Abstract

The machine (1) for digital printing of decorations on rigid supports (2), such as tiles or the like, comprises: a conveyor (3) for advancing the supports (2) along a conveying direction (D); a movable printing assembly (5) able to provide said decorations, arranged above said conveyor (5) and comprising a plurality of print heads for ink jet digital printing; moving means (61, 62, 63, 64, 7, 8) for moving the printing assembly (5); and a processing unit configured to activate said print heads and to control the moving means (61, 62, 63, 64, 7, 8). The processing unit comprises a control module configured to print on the support (2) by moving the printing assembly (5) according to a decoration sequence comprising a succession of continuous passes along respective printing directions parallel to the conveying direction (D).

Description

"Digital printer for rigid supports."

DESCRIPTION

The object of the present invention is a digital decorating machine for decorating rigid supports, especially but not exclusively intended for decorating ceramic objects, such as tiles, or glass objects or the like.

There are prior-art machines for printing decorations on ceramic tiles, which utilize inkjet technology, and they are called digital decorating machines.

Decorating machines usually include a conveyor belt, which is arranged to advance the ceramic items to be decorated, and an upper structure above the belt and comprising the print heads.

There are two basic groups of digital decorating machines: single-pass decorating machines, in which the belt advances the products "continuously", and multi-pass decorating machines, in which the belt is actuated with "step" advancement.

In the case of single-pass decorating machines, the print heads are fixed and grouped by colour on lines arranged transversely to the direction of advancement of the conveyor (the so-called "colour bars").

The advantage of adopting this type of decorating machine consists in its high output, given that the belt runs continuously, rather than being stopped.

However, the single-pass solution proves to be quite costly, given that a large number of print heads must be provided in order to achieve good printing resolution.

In further detail, in the case that one needs to operate on a printing width of 1800 mm, about 28 print heads per colour are needed (if the size of the print head is equal to 65 mm), with a total amounting of 168 print heads (for 6 colours).

Moreover, the single-pass solution proves to be less effective in the case of the production of large-sized tiles, which represent one of the items most in demand on the market today. In fact, the production of these tiles, which are much longer than traditional tiles, has an intrinsically low yield.

Conversely, multi-pass decorating machines make it possible to achieve excellent resolution with very limited costs.

In fact, in multi-pass decorating machines, the belt that conveys the item stops (or intermittently advances) during the decorating step, in which the printing assembly containing the print heads slides along an axis transverse to the direction of advancement; in the case of large-sized tiles, this axis of sliding movement is also transverse to the length of the item itself.

Multi-pass decorating machines currently present on the market suffer from the drawback of being rather slow and therefore they do not fully satisfy the needs of the ceramics sector.

The technical task underlying the present invention is thus to offer a machine, a method and a software program for the digital printing of decorations on rigid supports and that are capable of overcoming the limits of the prior art.

This task is achieved by the machine realized in accordance with claim 1 , by the method implemented according to claim 8 and by the computer program defined in claim 9.

Further characteristics and advantages of the present invention will become more apparent from the approximate and thus non-limiting description of a preferred, but not exclusive, embodiment of a printing machine according to the invention, as illustrated in the accompanying drawings, of which:

- Figure 1 is a schematic axonometric view of the machine in an at-rest operating configuration; and

- Figure 2 is the view of the preceding figure in which the machine is found in a working operating configuration.

With reference to the attached figures, the machine for digital printing (or decorating machine) of the invention is indicated by the number 1 . The machine 1 proposed has been devised to print decorations on rigid supports 2, such as tiles or other ceramic objects, but also on sheets of glass or other supports.

Herein below for the purposes of simplifying exposition and without loss of generality, reference is made to the use of the invention for printing on tiles 2, especially large-sized tiles, that is, tiles that are very long.

The machine 1 of the invention is an ink-jet and multi-pass type of machine.

The machine 1 includes at least one conveyor 3, for example a belt wound in a closed loop on special transmission rollers, for advancing the supports along a conveying direction (D).

The belt, or another type of conveyor 3, is supported by a bed 4 that also comprises the motorized means for the advancement thereof.

The dimensions of the elongated upper mat 30 defined by the belt 3, that is, the upper branch of the loop defined by the belt 3 on which the tiles 2 rest, are such that they at least match the maximum size of tiles to be decorated.

Preferentially, as explained in further detail below, the belt 3 is actuated for step movement, not continuous movement.

The construction-related aspects of the bed 4, the belt 3 and motorization can be drawn from the prior art.

The invention then comprises a movable printing assembly 5 that is able to provide the decorations on the supports 2 and arranged above the belt 3. In further detail, the printing assembly 5 comprises a plurality of print heads for ink jet digital printing, grouped together, along with known means for their operation, such as the operating logic, delivery and return lines, etc.

For example, the printing assembly 5 is contained in a supporting protective shell that moves above the printing zone, that is to say, above the belt 3 conveying the tiles 2. The proposed machine 1 also includes means 61 , 62, 63, 64, 7, 8 for moving the printing assembly 5, preferably of the type having three degrees of freedom, even though an embodiment in which they can have two degrees of freedom is not ruled out in principle.

In the preferred embodiment shown in the figures, the moving means 61 ,

62, 63, 64, 7, 8 include four guide elements 61 , 62, 63, 64 in the form of shaped rectilinear beams, realized for example starting from section bars. Of these four beams 61 , 62, 63, 64, two 61 , 62 are movable and located parallel to the conveying direction D, whereas the two remaining beams 63, 64 are mounted in a fixed manner in the machine 1 and they are perpendicular to the above-mentioned conveying direction D of the belt 3. The first beams 61 , 62, that is, the beams that are parallel to the conveying direction D, support the printing assembly 5, which is slidingly constrained to them, so as to be movable longitudinally with respect to the belt 3.

The printing assembly 5 can be slidably connected to the first guide beams 61 , 62 by means of special sliding blocks or carriages 7.

These first beams 61 , 62 are, in turn, slidably coupled to the second beams 63, 64 so as to enable the printing assembly 5 to move transversely to the belt 3. The first beams 61 , 62 can be connected to the second beams 63, 64 by means of special sliding blocks or carriages 8. More specifically, the second beams 63, 64 can be located upstream and downstream of the belt 3, that is, in proximity to the longitudinal opposite ends of the belt 3, but outside of the perimeter defined by the latter.

The first beams 61 , 62 are arranged between the second beams 63, 64 above the belt 3, and they are slidingly coupled to the second beams 63, 64 at their own longitudinal opposite ends.

Moreover, the structure made up of the first and the second beams 61 , 62,

63, 64 can be connected to actuators or additional guides, so as to raise or lower itself, thereby realizing a third degree of freedom of the moving means 61 , 62, 63, 64, 7, 8. In fact, in use, the printing assembly 5 moves from a lower position, in which it is located at a distance from the tile 2 such as to be able to print the decorations on it, to a raised position. This aspect shall be dealt with in further detail below.

The first and the second beams 61 , 52, 63, 64, like the above-mentioned sliding carriages or blocks 7, 8 can constitute the components of respective linear motors. The vertical movement can instead be actuated by recirculating spheres motors.

In any case, design solutions for the moving means 61 , 62, 63, 64, 7, 8 differing from those illustrated above can be adopted, but they must fall within the proposed inventive concept.

In more general terms, the moving means 61 , 62, 63, 64, 7, 8 comprise at least a first guide element 61 , 62 (preferably two as explained hereinabove) to which the printing assembly 5 is slidingly constrained and at least a second guide element 63, 64 (preferably two) to which the first guide element 61 , 62 is slidingly constrained.

The first and the second guide elements 61 , 62, 63, 64 can be rectilinear, as in the case of the beams of the embodiment described above.

In this case, the second element 63, 65 is fixedly mounted and arranged transverse to the conveying direction D, whereas the first element 61 , 62 is movable and arranged parallel to the conveying direction D.

Again in general terms, the movement means 61 , 62, 63, 64, 7, 8 and the printing assembly 5 constitute a Cartesian plotter of a sort that can move along a planar surface of the tile 2 or of another support. However, as discussed in further detail herein below, this plotter is advantageously commanded to carry out printing by subsequent passes along directions parallel to the conveying direction D of the belt 3, which is preferably also the direction of extension in the length of the belt 3 and of the large-sized tiles 2 discussed above. The invention comprises the use of a processing unit configured to activate said print heads and to control said moving means 61 , 62, 63, 64, 7, 8; the processing unit can also control the advancement of the belt 3. In general, it should be noted that in the present description, the processing unit is presented as subdivided into distinct functional modules for the sole purpose of describing the functions thereof clearly and thoroughly.

In practice, this processing unit can be constituted by a single electronic device, even of the type commonly present on this type of machine, suitably programmed for performing the functions described, and the various modules can correspond to hardware entities and/or routine software that are part of the programmed device.

Alternatively, or additionally, these functions can be performed by a plurality of electronic devices on which the above-mentioned functional modules can be distributed.

The processing unit can make use of one or more microprocessors for execution of the instructions contained in the memory modules, and the above-mentioned functional modules can be distributed in a plurality of computers, locally or remotely, based on the architecture of the network in which they reside.

According to an important aspect of the invention, the processing unit comprises at least one control module configured to print on the support 2 by moving the printing assembly 5 according to a decoration sequence. The decoration sequence comprises the completion of a succession of continuous passes along respective printing directions that are parallel to the conveying direction D, that is to say, along the length of the belt 3 and also of the tiles 2, if the latter are large-sized, in the direction specified above.

Therefore, unlike multi-pass machines of the prior art, the invention prints using a sequence of longitudinal passes on the large-sized tiles 2. In practice, with each pass, the printing assembly 5 produces a printed longitudinal band or line on the upper surface of the tile 2 (intended to remain exposed to view); another way of explaining this is that with each pass, a decorated longitudinal portion is produced on the exposed surface of the tile 2.

Following the printing of a plurality of adjacent longitudinal portions of the upper surface of the tile 2, the final decoration is obtained. The above- mentioned decoration sequence is pre-programmed based on the specific characteristics, such as the geometric characteristics, of the support 2 to be printed.

For the purpose of achieving high definition of the decoration, the control module can carry out a number of passes in the same printing direction, that is, over the same longitudinal portion of the surface of the tile 2.

Owing to the capacity to print the tiles 2 longitudinally and not transversely, a yield greater than that of the prior art is obtained, given that, with the surface to be decorated being equal, the printing procedures are decidedly faster.

Therefore, the invention makes available an "accelerated" multi-pass machine 1 , thereby satisfying the need to have machines that are less costly than single-pass machines, but faster than the multi-pass machines currently available on the market.

In fact, it has been found that a machine 1 comprising 48 / 64 print heads can print a ceramic slab measuring 3100 x 1920 mm in about 40 seconds. In further detail, the invention envisages that printing be carried out only by longitudinal passes, whereas the transverse movement of the printing assembly 5 is used to pass to an additional parallel printing direction, that is, to print another portion of the tile surface alongside the portion that has already been decorated.

In terms of the functionality of the processing unit, the information stated in the previous paragraph means that the control module is preferably configured to move the printing assembly 5 in such a manner that between one or more passes along the printing direction, the assembly is moved transversely to the conveying direction D, so as to enable one or more passes to be carried out along a different printing direction.

In further detail, between one pass (or a number of passes) along one direction and the pass in an adjacent direction, the printing assembly 5 is moved transversely so as to pass from the first direction to the second direction.

Moreover, for the purpose of printing on the entire extension of the surface of the tile 2 to be decorated, the control module is preferably configured to carry out the above-mentioned continuous passes so that each pass begins and ends at opposite ends 21 , 22 of the tile 2, that is to say, at opposite sides of the perimeter of the tile.

The control module can be configured to move the printing assembly 5 from a lower position to a raised position, for example for maintenance procedures.

The processing unit can include a transport module configured to command the conveyor 3 into step advancement in phase relation to the above-mentioned decoration sequence.

In practice, the conveyor 3 leads the tile 2 to rest in the printing space and Stops.

At this point, the printing assembly 5 is brought to one end 21 , 22 of the tile or to a given internal point and it carries out one or more longitudinal passes in a first longitudinal direction, so as to realize a first decorated rectilinear portion as long as the entire upper surface of the tile 2.

This portion is preferably as long as the tile 2, that is, it extends from opposite edges 21 , 22 of the tile.

At this point, one or more passes are carried out in a direction parallel to that of the first portion that has been decorated, so as to produce a second decorated portion adjacent to the first decorated portion. These procedures are repeated until the decoration of the surface of the tile 2 is completed. The decorated tile 2 is then advanced so that it leaves the printing zone, while the next tile 2 is brought into position and so on. Preferentially, the transport module keeps the belt 3 stopped and thus the tile 2 as well, during the entire printing process, but an embodiment in which movement of the belt 3 cooperates with that of the printing assembly 5 for the purpose of realizing the desired decoration is not excluded.

The invention also constitutes a method for decorating a rigid support 2, comprising the following steps:

- providing the above-mentioned printing assembly 5, comprising a plurality of print heads for ink jet digital printing;

- providing a rigid support 2 having a surface to be decorated, such as a tile 2 for example or a slab with a flat upper surface;

- step moving the rigid support 2 along a conveying direction D; and - decorating the surface of the support 2 by means of the printing assembly 5, preferably when the support 2 is stopped, the printing assembly 5 carrying out a plurality of continuous passes along printing directions parallel to the conveying direction D.

All of the functions of the machine 1 that are illustrated herein above, particularly the procedures carried out by the modules of the processing unit, constitute just as many possible steps of the method that can be carried out as single or combined steps.

Lastly, the invention also includes a computer program that implements the steps of the method, when running on a processing unit.

Claims

A machine (1 ) for digital printing of decorations on rigid supports (2), such as tiles or the like, comprising:

at least one conveyor (3) for advancing the supports (2) along a conveying direction (D);

at least one printing assembly (5) movable, able to provide said decorations, arranged above said conveyor (3) and comprising a plurality of print heads for ink jet digital printing;

moving means (61 , 62, 63, 64, 7, 8) for moving said printing assembly (5); and

at least a processing unit configured for operating said print heads and control said moving means (61 , 62, 63, 64, 7, 8); characterized in that said processing unit comprises at least a control module configured for printing on the support (2) by moving the printing assembly (5) according to a decoration sequence comprising a succession of continuous passes along respective printing directions parallel to the direction of transport (D).

A machine (1 ) according to the preceding claim, wherein said control module is configured to perform said continuous passes so that each pass begins and/or ends at opposite ends (21 , 22) of the rigid support (2).

A machine (1 ) according to at least any preceding claim, wherein said moving means (61 , 62, 63, 64, 7, 8) are suitable for moving the printing assembly (5) according to at least two degrees of freedom, said control module being configured to move the printing assembly (5) within said decoration sequence in such a way that, between one or more passes along a printing direction, the printing assembly is moved transversely to the conveying direction (D), thereby allowing one or more passes to be performed along a different printing direction.

A machine (1 ) according to the preceding claim, wherein said moving means (61 , 62, 63, 64, 7, 8) are able to move the printing assembly (5) according to at least three degrees of freedom, said control module being configured to move the printing assembly (5) from a lower position to a raised position.

A machine (1 ) according to at least any preceding claim, wherein said moving means (61 , 62, 63, 64, 7, 8) comprises a first guide element (61 , 62) to which the printing assembly (5) is slidingly coupled and a second guide element (63, 64) to which said first guide element (61 , 62) is slidingly constrained.

A machine (1 ) according to the preceding claim, wherein said first and second guide element (61 , 62, 63, 64) are rectilinear, the second element (63, 64) being fixedly mounted and arranged transverse to the conveying direction (D), the first element (61 , 62) being movable and arranged parallel to the conveying direction (D). A machine (1 ) according to the preceding claim, wherein the processing unit comprises a transport module configured for operating said conveyor in a step advancement of (3) in phase relation to said decoration sequence.

A method for decorating a rigid support, comprising the following steps:

providing a printing assembly (5) comprising a plurality of print heads for ink jet digital printing;

providing a rigid support (2) having a surface to be decorated; step moving said rigid support (62) along a conveying direction (D); and

decorating said surface of the rigid support (2) by means of said printing assembly (5), by performing a plurality of continuous passes along print directions parallel to said conveying direction (D).

A computer program able to carry out the steps of the method of the preceding claim, when running on a processing unit.