DESCRIPTION

TECHNICAL FIELD OF THE INVENTION

The present invention refers to an anilox roll cleaning equipment, which has application in the flexographic printing industry, and more specifically in the field of cleaning systems for these rolls, allowing them to be cleaned in a convenient way without damaging them and also allowing a plurality of rolls to be cleaned at the same time without the need to take up much space in the plant.

BACKGROUND TO THE INVENTION

Flexographic printing is an indirect printing process in which a motif or image is printed on a substrate, which can be plastic, paper, cardboard, etc., using a combination of colours. Each of these colours transfers the ink by means of a "stencil" made, today, with a photopolymer resin that takes the ink from a cylinder or anilox roll. In turn, the anilox roll takes the ink from a doctor blade chamber which is fed by a pneumatic or electrical system from a container which is usually placed at a short distance from the printing unit.

The anilox roll is a cylinder, solid or sleeve, coated with ceramic, specifically chromium oxide, whose cylindrical surface is laser engraved in order to create a certain number of holes per linear centimetre, with a certain pattern, shape and angle with respect to the horizontal.

The anilox roll is an indispensable part of the printing equipment as it is responsible for transferring the correct amount of ink from the doctor blade chamber to the printing plate and, depending on its maintenance, the quality of the print result can vary enormously.

As mentioned, the anilox roll is impregnated with ink by a roll and a blade removes the excess ink from the anilox roll, where the ink fills cells engraved on the anilox roll, whose ink is finally transferred to the printing roll cliche and from there to the material to be printed.

Over time, it is inevitable that the ink will dry out in the cells of the anilox roll and lose its initial quality.

Currently, there are several methods for cleaning this ink, which involve the use of a laser and the suctioning of the dried ink. However, current cleaning methods include the following options:

- Chemicals.

- Ultrasound.

- Water/detergent/solvent spraying under pressure.

- Laser.

Focusing on laser technology, there are several laser anilox cleaning systems available to date, as described below.

The international application with publication number WO-2018/224717-A1 describes a laser anilox roll cleaning machine comprising a multi-laser head with two or more laser modules that generates two or more contiguous focal points, the spacing of which can be modified by moving the laser modules along a guide. It also incorporates a feeler wheel associated with an encoder operationally connected to the machine's electronic system and, in particular, to the emergency stop system.

On the other hand, Spanish patent application no. ES-2390039-A1 describes a system for cleaning anilox and cylindrical surfaces by laser, comprising a mechanical structure that maintains a rotation system where the roll to be cleaned is supported and rotated, a filtration system, and a controller with a user interface. It also has a laser resonator that fires a beam at the power required to remove debris from the roll. This laser is fixed to a linear displacement system that makes it advance parallel to the cylindrical cleaning surface and at the appropriate speed in synchronisation with the speed of rotation of the roll, so that it covers the entire surface with the beam.

In any case, the systems in the state of the art only allow cleaning one roll at a time and also take up a lot of floor space, as a result of the horizontal arrangement of the rolls in the cleaning machine, which also makes them difficult to handle for the user who operates the cleaning machine, especially when placing and removing the machine, as well as handling the roll itself.

DESCRIPTION OF THE INVENTION

The present invention relates to an anilox roll cleaning equipment, comprising a laser, as defined in claim 1. According to the invention, the equipment comprises a loading platform which in turn has at least one adapter on which an anilox roll to be cleaned by means of the laser is arranged, which moves vertically for the complete cleaning of each anilox roll arranged on each adapter.

Therefore, the arrangement and loading of the anilox rolls, whether solid or sleeves, for laser treatment is vertical, in contrast to the state of the art.

In contrast to the horizontal arrangement of the systems of the prior art, the vertical arrangement and loading proposed by the invention has several advantages:

1- ergonomics. Easier loading.

2- simplicity. It is much simpler as a structure.

3- stability. The rolls rest on the base and there is no risk of displacement, so there is no need to devise a system to stop this displacement.

4- energy saving. Electricity consumption is much lower when rotating the base than when rotating an oscillating carousel loaded with anilox. The weight is supported by a bearing, not a motor.

It is envisaged that the loading platform may comprise a rotating base having a plurality of adapters evenly distributed radially, so that each adapter allows for the provision of an anilox roll for cleaning.

In this way, up to 10 rolls can be cleaned, whereas the state of the art only cleans one roll at a time and in a horizontal position, which takes up more space. Thus, the equipment of the invention can load up to 10 anilox rolls, making the equipment highly productive and allowing customers to clean a large number of anilox rolls on a recurring basis, thus guaranteeing optimum print quality. With the possibility of loading several rolls, it is possible to save time in the loading and unloading operation of the equipment, which, by rotating the loading platform, can clean all the rolls, without the need to intervene until all the rolls loaded in the equipment have been cleaned.

The aniloxes are loaded on a rotating base that incorporates as many adapters as aniloxes can be loaded. These adapters have the necessary height so that, once placed on the structure, when the structure is rotated, they maintain their verticality and do not swing, fall or hit each other. It is envisaged that the adapters will be mounted on a folding support, which is a metal part that may incorporate a spring/damper that, in the unloaded position, holds the adapter at a 45° angle to facilitate loading of the anilox. Once the anilox is in place, the weight of the anilox itself (approximately 15 kg) keeps the adapter in its lowest position. With regard to how each anilox is loaded, each adapter, by means of the folding support on which it is placed, is positioned at an angle of 45 degrees, so that all you have to do is reach in with the anilox, thread it and the weight of the anilox itself lowers it to the working position. The equipment also has protective screens in each anilox position.

It is envisaged that the equipment will include motive means to produce rotation of the rotating base, such as a motor, facilitating loading and unloading operations.

It is also envisaged that the equipment will include a PLC to control the rotation of the rotating base and the correct positioning of the rotating base in relation to the anilox roll to be cleaned.

As an element of protection and safety, the equipment includes a motorised shutter that controls access to the loading platform. This ensures safety for the operator and for sensitive parts of the machine. The operator can choose to load all aniloxes at the same time or, in case he wants to load/unload an anilox at a random time, the machine will allow him to do so only between cleaning cycles. The cleaning cycle allows the operator a window of time in which he can remove/load an anilox or take no action and the machine will proceed to clean the next anilox.

Aniloxes of various dimensions can be cleaned in this equipment thanks to a system called Touch & Clean by means of which a laser sensor performs a topography of the anilox to determine its diameter and length, essential data for the positioning of the lens and subsequent cleaning. The length is read by means of a torque control in the positioning servo of the anilox turning head.

Once the anilox is inserted, it has no top support as long as it is not in the cleaning position. Once it reaches the cleaning position, an arm at the rear of the machine, equipped with an upper retaining element, which may also be called an expandable claw, is inserted into the core and expands until the anilox is in the correct position.

The positioning of this gripper is carried out by means of a servo motor with torque control, coupled to a structure made of a plastic material, which, starting in the highest position, will descend by means of a worm screw and double linear guide, until it makes contact with the surface of the anilox with the torque control adjusted to the ideal value that detects the presence of the anilox without damaging it. Once in the correct position, the gripper, also equipped with a torque-controlled motor, will expand and fix the anilox.

Once the anilox is fixed, a servo motor will be responsible for turning it at the speed set by the algorithm that has been previously introduced in relation to the laser configuration, type of cleaning and diameter of the anilox. The motor can be encoder- driven, by direct drive, but it could also be positioned laterally with a belt drive.

The laser head is located in the centre of the structure and is mounted on a support supported by two linear guides that moves vertically and parallel to the surface of the anilox, on a worm screw, directly coupled to a servomotor. The displacement speed of this head is established by the algorithm and in relation to the laser configuration, type of cleaning and diameter of the anilox.

The equipment incorporates an automatic focusing system which, depending on the diameter of the anilox inserted in the machine, calculated by the laser sensor previously mentioned, positions the laser head, mounted on two linear guides and a worm screw, by means of a servo, at the appropriate focal distance, established by the manufacturer. To ensure effective cleaning and proper maintenance of the equipment, a fume extraction system is incorporated with a vacuum nozzle located on the laser head and a few millimetres from the surface of the anilox. The air will be passed through a filter that will collect the particles of ink and/or varnish evaporated by the laser beam.

The equipment consists of redundant safety systems such as:

- Switch on the roll shutter that stops the machine if it opens.

- Anilox detector that prevents the laser from firing if it does not detect an anilox.

- Motion detector that prevents the laser from firing or stops the laser in operation if it detects that the head is not moving correctly.

- Motion detector that prevents the laser from firing or stops the laser in operation if it detects that the anilox is not rotating correctly.

The equipment incorporates a touch interface from which to control all its operations. The operations to be controlled from the interface are:

- Language selection

- Identification of the anilox

- Selection of the type of cleaning

- Monitoring and reporting of the ongoing cleaning process.

- Communication with the PLC for maintenance work.

- Alarm control and management

- Parameterisation of the laser source.

The equipment incorporates 3 LED lights indicating the status of the machine and informing about it by means of different colours. These LED lights are placed on the upper part of the machine for better visibility.

DESCRIPTION OF THE DRAWINGS

To complement the description being made and in order to assist in a better understanding of the features of the invention, in accordance with a preferred example of a practical embodiment thereof, a set of drawings is attached hereto as an integral part of the said description, in which the following is illustratively and non-limitingly depicted:

Figure 1.- Shows a schematic perspective view of the anilox roll cleaning equipment proposed by the invention, in which the adapters with the elastic stops located on the folding supports and a single anilox roll (A), which is immobilised in the equipment by means of the retaining column, can be seen.

Figure 2.- Shows a view as in the previous figure with an anilox roll (A) located in each of the adapters.

Figures 3 and 4.- Show two profile views of the equipment in the previous figure, in which it can be seen how the upper sliding element of the retaining column is positioned on top of the roll being cleaned.

Figure 5.- It shows a perspective view of the execution represented in the previous figures in which the rolls are not shown and only an adapter placed on a folding support, for a better appreciation of the function of this element that can be housed in spaces located in the loading platform itself, coplanar with it, and can also be folded outwards from the perimeter of the platform so that the operator can place the roll on the adapter at an angle without having to fit it vertically, which would entail a greater effort and risk of falling.

Figure 6.- Shows a detail in perspective from the rear of the equipment in which the location of the laser can be seen, as well as an adapter placed on a folding support.

Figure 7.- Shows a detail like the view in the previous figure from the opposite side.

Figure 8.- Shows a plan view, from a zenithal viewpoint, of the view shown in figure 2.

Figure 9.- Shows a detail in perspective, from another angle, of the view shown in figure 1 .

Figure 10.- Shows a detail in elevation of the loading platform with the adapters and spacers, with one of the folding supports inclined and in which the driving means can be seen, in the case shown, located under the loading platform itself.

Figure 11.- Shows a perspective view of the retaining column, in which the relative position of the laser and the upper retaining element of the anilox rolls (A) is also shown.

PREFERRED EMBODIMENT OF THE INVENTION

In view of the figures shown, it can be seen that in one of the possible embodiments of the invention, the equipment proposed by the invention allows the cleaning of anilox rolls (A) for which the equipment comprises a laser (1), preferably a fibre optic laser. The equipment comprises a loading platform (2) which in turn has at least one adapter (3) on which an anilox roll (A) to be cleaned by means of the laser (1) is placed. In the embodiment shown in the figures, the components of the equipment are placed on a frame made up of metal profiles.

In a working position of the equipment, in which the laser (1) performs the cleaning of at least one anilox roll (A), said anilox roll (A) is kept in a vertical position perpendicular to the loading platform (2). As a result of the vertical arrangement of the anilox rolls (A) during the cleaning operation, the floor space occupied by the equipment is little more than that occupied by the loading platform (2) itself, on which several anilox rolls (A) are placed, up to a number of up to 10.

According to the embodiment shown in the figures, the loading platform (2) consists of a rotating base with a number of adapters (3) evenly distributed radially with respect to its centre of rotation (2'), so that each adapter (3) allows the arrangement of an anilox roll (A) for cleaning.

Each adapter (3) is placed on a folding support (4) comprising the loading platform (2), so that this folding support (4) can be fitted to the loading platform (2) and can move between a first position in which it is coplanar with the loading platform (2) itself and a position in which it is in a plane inclined towards an external area in correspondence with the contour of the equipment, to facilitate the positioning of the anilox rings (A) on the adapters (3).

Furthermore, each adaptor (3) comprises at least one elastic stop (5) that tightly contacts the inner generatrix of the anilox roll (A), allowing its centred positioning in the adaptor (3).

As shown in the figures, the loading platform (2) comprises a plurality of spacers (6) between adapters (3).

The equipment comprises driving means (7) to produce the rotation of the loading platform (2). The drive means (7) may consist of a motor for rotating the platform (2) which may be located in the centre of the platform (2) or at the side, close to the electrical panel and driven by a belt.

In total, the equipment can incorporate up to 5 engines:

Platform slewing motor: servomotor with rotary indexing table.

Anilox turning motor: motor with encoder, with belt drive.

Autofocus motor: servo motor, spindle.

Laser travel motor: servomotor, spindle.

Grapple travel motor: electrically driven cylinder.

The equipment comprises a PLC to control the rotation of the loading platform (2) and the correct positioning of the loading platform (2) according to the anilox roll (A) that needs to be cleaned.

The equipment also comprises a retaining column (8) comprising means for retaining the anilox roll (A) during the cleaning operation. As can be seen in the figures, the retaining column (8) comprises a vertically movable upper element along a guide that can be fitted into the upper end, obviously hollow, of the cylinder being cleaned, thus ensuring its total immobilisation when the laser is in operation. For its release, the upper sliding element rises, allowing the loading platform (2) to rotate in order to place the next anilox roll (A) to be cleaned facing the retaining column (8).

Finally, although not depicted, it is envisaged that the equipment will comprise a motorised roll shutter that controls access to the loading platform.

In view of this description and set of figures, the person skilled in the art will understand that the embodiments of the invention that have been described can be combined in multiple ways within the subject matter of the invention. The invention has been described according to some preferred embodiments thereof, but it will be apparent to the person skilled in the art that multiple variations can be introduced into such preferred embodiments without exceeding the claimed subject matter of the invention.