EP1435292B1

EP1435292B1 - Process and system for automatically loading and unloading matrix printing plates on cylinders for printing assemblies for flexographic printing machines

Info

Publication number: EP1435292B1
Application number: EP03425001A
Authority: EP
Inventors: Mario Forno; Mauro Lavagno
Original assignee: Officine Meccaniche Giovanni Cerutti SpA
Current assignee: Officine Meccaniche Giovanni Cerutti SpA
Priority date: 2003-01-02
Filing date: 2003-01-02
Publication date: 2006-03-15
Anticipated expiration: 2023-01-02
Also published as: DE60304024D1; ATE320346T1; GB2435238A; EP1435292A1; GB0702483D0

Abstract

A process and a system are disclosed for automatically loading and unloading matrix printing plates (1) on cylinders (3) for printing assemblies (5) for flexographic printing machines. Through such process and such system, it is possible to do without long and cumbersome installation and removal phases of the plates (1) that before were completely manually carried out. When loading, the plates (1), once having been placed on a frame (7), are supplied, hooked and fixed to the cylinder (3) in a completely automatic and controlled way, while, when unloading, they are firstly unhooked and then taken back onto the receiving frame (7). <IMAGE>

Description

The present invention refers to a process and a system for automatically loading and unloading matrix printing plates (namely, printing plates of the matrix type) on matrix-holding cylinders (namely, cylinders for holding printing plates of the matrix type) used in printing assemblies for rotating machines for flexographic printing.
In the flexographic printing field, for example for printing newspapers or various publications, it is necessary to load and unload matrix printing plates on matrix-holding cylinders through a first securing operation to fixed hooking means of the cylinder and then, after having rotated the cylinder, an opening operation of mobile hooking means in order to place thereon the rear end of the plate for the final fixing. All above-listed operations, including opening of the mobile hooking means, are manually performed, with obvious problems of times, accuracy and dangers for the operators (since the plates are made of metallic material and have cutting edges).
In applications implying the printing of newspapers, where every matrix-holding cylinder contains 8 plates to be placed on its surface, and where, in a printing machine, there are a plurality of printing assemblies, each one containing four cylinders (for four-colour printing), the cylinders can easily reach 40 as a number and the total plates 320 as a number. With these numbers, it is evident that, as it often occurs when printing newspapers, when it is necessary to replace at the last possible moment and quickly one or more plates in particular cylinder positions and in particular printing assemblies, the operations of removing the old plate and of replacing it with a new plate require long times by a single operator, or require the presence of many operators, in the end creating long, complex and costly processes.
While in the offset printing field there have been disclosed some partially-automated arrangements in plate-hooking operations (for example in documents DE-A-10024087 US-B-6199280, GB-A-2277903, or DE-A-10139292), the different structure of plates of the offset type (that are generally made of aluminium and therefore are of a metallic, but not magnetic, material, differently from plates for flexographic printing) and the different needs for their connection to cylinders imply solutions that cannot be applied to the flexographic printing field. In such field, instead, there are nowadays no processes or systems that allow automatically loading or unloading plates on or from matrix-holding cylinders.
Object of the present invention is solving the above-said prior art problems, providing a completely automated process and system for loading and unloading matrix printing plates on or from matrix-holding cylinders, thereby removing all manual prior art operations, reducing tooling times and costs and reducing the number of working operators.
A further object of the present invention is providing a process and a device of the above-mentioned type that allow automating also the steps upstream of those of installing the plates, thereby providing a completely automated line in which the plates are prepared in composition, recognised by readers and sensors, and then transported downstream for the automatic assembling on matrix-holding cylinders.
The above and other objects and advantages of the invention, as will readily appear from the following description, are obtained by a process and a system for loading the plates on matrix-holding cylinders, and by a process and a system for unloading the plates from matrix-holding cylinders as pointed out in the independent Claims. Preferred embodiments and non-trivial variations of the present invention are the object of the dependent Claims.
The present invention will be better described by some preferred embodiments thereof, provided as a nonlimiting example, with reference to the enclosed drawings, in which:

Figure 1 is a schematic side view of a printing assembly comprising four preferred embodiments of the system of the present invention in respective orientations according to the placement of the four matrix-holding cylinders used for four-colour printing;
Figure 2 is a schematic view that shows the positions of eight plates on two respective matrix-holding cylinders;
Figure 3 is a front view of a matrix-holding cylinder and the frame;
Figure 4 is a detailed view of the cylinder and of one of the plate-holding means;
Figure 5 is a more detailed side sectional view of the printing assembly in Fig. 1;
Figure 6 is an enlarged view of part of Fig. 5 that shows one of the four systems of the invention contained therein;
Figure 7 is a side view that better shows the cam control means for the wheels of the system of the invention;
Figure 7A is a front view corresponding to Fig. 7;
Figure 8 is a front view of the wheels and the coaxial cylinders supporting them;
Figures 9 to 12 are four top views of the four operating positions of the cam control means; and
Figures 13 to 36 are views of the various detailed steps of the process of the invention, seen from two different operating positions.

With reference to the Figures, a preferred embodiment of the system for automatically loading and unloading plates 1 on and from matrix-holding cylinders 3 of printing assemblies 5 of flexographic printing machines, is shown.
Such system substantially comprises:

means 7 for receiving and inserting the plate 1 on the matrix-holding cylinder 3;
fixed hooking means 9 for the matrix-holding cylinder 3, commonly known in the art, that are adapted to hook the front end of the plate 1, after that it has been placed on the means 7 and has been advanced till it engages the fixed hooking means 9;
pushing means 8 adapted to push the plate 1 to engage the fixed hooking means 9;
pressing means 12 for keeping the plate 1 in contact with the external surface of the matrix-holding cylinder 3 during its rotation;
opening means 16, 18, 20, 22, 24, 26, controlled by control means 28, 30, 32, adapted to open the mobile (the term "mobile" meaning that the hooking means 23 are adapted to be moved between an opened and a closed position with respect to the fixed means 9 in order to hook the plate-the term "opening means" pointing out the action that separates the mobile hooking means 23 from the fixed means 9) hooking means 23 of the matrix-holding cylinder 3 during a first rotation of the cylinder 3 to place thereon the rear end of the plate 1, and adapted to close the mobile hooking means 23 in gripping engagement with the rear end of the plate 1.

For a better final operation, as will be described below, the above-mentioned system can further comprise attracting means 34 for attracting the front end of the plate 1 in a position adapted to facilitate its supply on the matrix-holding cylinder 3 or its supply on the receiving means 7.
According to the embodiment shown, every matrix-holding cylinder 3 is adapted to contain a plurality of matrix printing plates 1 on its external surface, and each one of the plates 1 comprises an identification code (not shown); with such configuration, adapted for the final, completely automated solution, the system further comprises:

means for programming a loading sequence of the plates 1 on the matrix-holding cylinder 3, in which such programmed sequence is stored in a central control and command unit (not shown), and in which the sequence establishes the identification code of the respective plate 1 to be placed in one of the foreseen positions on the matrix-holding cylinder 3;
means for automatically supplying the plurality of plates 1 onto the receiving and inserting means 7;
means for reading the identification code of each one of the plates 1 and coupling it with the identification code of the programmed sequence; and
means for loading each one of the plates 1 onto the matrix-holding cylinder 3 according to the programmed sequence contained in the central control and command unit.

Moreover, the above-described system can further comprise strongly-attracting means 36 (for example at least one electromagnet) placed in the receiving means 7: such strongly-attracting means 36 attract the plate 1 against the receiving means 7 by overcoming the thrust force provided by the rotation of the matrix-holding cylinder 3, and thereby the plate 1 is kept in a fixed and unmoving position on the receiving means 7 by the strongly-attracting means 36 to realise the final unloading of the plate 1 from the cylinder 3.
The above-described system is adapted to realise the loading and unloading of plates 1 according to the established means and sequences; if a completely automated operation of unloading already-installed plates 1 on the cylinder 3 is also made necessary, the system is further equipped with:

means for programming a sequence of unloading of plates 1 from the matrix-holding cylinder 3, in which such programmed sequence is stored in a central control and command unit, and in which the sequence establishes the identification code of the respective plate 1 to be extracted from one of the provided positions on the matrix-holding cylinder 3; and
means for unloading each one of the plates 1 from the matrix-holding cylinder 3 on the receiving means 7 according to the programmed sequence contained in the central control and command unit.

Pushing means 8 (composed of at least one piston) can further be present for pushing the plate 1 in an operating position on the hooking recess that can be found on the cylinder 3.
The Figures show a practical preferred, but nonlimiting, embodiment of the system of the invention. According to what is shown in such Figures, therefore, for example the receiving and inserting means 7 can be composed of a frame 7 that is extended for the whole longitudinal extension of the matrix-holding cylinder 3: such frame 7 is equipped with holding means 40 of the plates 1 against the frame 7 during their sliding movement on the frame 7. The frame 7 is further equipped with detecting means 42 for the position of the plates 1, in which the detecting means 42 are adapted to rotatingly control the matrix-holding cylinder 3 in order to phase its position with respect to the advancement of the plates 1 for their phased loading or unloading on or from the cylinder 3.
In particular, the holding means 40 are composed of a plurality of magnets 40 and the detecting means 42 are composed of a plurality of sensors 42.
Moreover, the frame 7 can be further equipped with rotating means 44 (preferably composed of a plurality of rubber wheels 44) whose rolling action facilitates the displacement of the plates 1 on the frame 7.
In the above-described preferred embodiment of the system, moreover, the pressing means 12 are composed of at least one rubber wheel 12, and the attracting means 34 are composed of at least one magnet 34.
Still more, the opening means 16, 18, 20, 22, 24, 26 are composed of a first and a second wheel 16, 18 adapted to roll onto the surface of the control means 28: the first and second wheels 16, 18 are respectively integral (through a junction 19) with a third and a fourth wheel 20, 22, that are adapted to control the mobile hooking means 23 and that are placed at an end of a respective toothed shaft 24, 26. The movement of the movable hooking means 23 is transferred, for the whole extension of the matrix-holding cylinder 3, from the wheels 16, 18, 20, 22 to the movable hooking means 23 themselves through the toothed shafts 24, 25 that are mechanically connected to the movable hooking means 23.
Moreover, the control means 28, 30, 32 are preferably composed of a cam 28 adapted to engage the first and second wheels 16, 18 during a rotation of the matrix-holding cylinder 3 in order to move the first and second wheels 16, 18 in an opening position of the mobile hooking means 23; then, the cam 28 is adapted to release the engagement of the first and second wheels 16, 18 during a further rotation of the matrix-holding cylinder 3 in order to snap the mobile hooking means 23 in engagement with the rear end of the plate 1, and moreover the cam 28 is adapted to assume a rest position, in which the cam 28 does not interfere with the rotation of the matrix-holding cylinder 3 and does not engage the first and second wheels 16, 18: the cam 28 assumes such rest position through the pull of elastic means 30 (commonly a pair of springs 30). Finally, the cam 28 is adapted to further assume a working position, in which it engages the first and/or second wheel 16, 18, and the cam 28 assumes such working position through the thrust of piston means 32 (commonly in a number of two, to guarantee an uniform thrust of the cam 28 itself to its working position).
In particular, the piston means 32 are adapted to move the cam 28 in three respective working positions, one in engagement with the first wheel 16 only, one in engagement with the second wheel 18 only and one in engagement both with the first wheel 16 and with the second wheel 18, to allow the engagement of three possible combinations of plates 1 on the matrix-holding cylinder 3.
The described system performs the loading operations when the cylinder 3 moves along a direction (called A), while it performs the unloading operations when the cylinder 3 moves in a direction (called B) whose sense is opposite with respect to the one of the loading direction A.
Moreover, in case of printing newspapers as shown in the Figures (where for clarity the wider printing stations each comprising a plurality of printing assemblies 5 have been omitted), every matrix-holding cylinder 3 contains eight matrix printing plates 1 mutually placed side by side on its external surface. It is obviously possible to provide for other cylinder configurations, containing a greater or lower number of plates 1, according to the end product that has to be obtained.
With the above-described system, it is possible to realise, with the same equipment, a process for loading and a process for unloading plates 1 on and from matrix-holding cylinders 3 as described below.
First of all, the process for automatically loading matrix printing plates 1 on matrix-holding cylinders 3 on printing assemblies 5 for rotary flexographic printing machines of the present invention substantially comprises the steps of:

placing at least one matrix printing plate 1 on the means 7 for receiving and inserting the plate 1 on the matrix-holding cylinder 3;
slidingly advancing the plate 1 on the receiving and inserting means 7 till the front end of the plate 1 arrives at a coupling position with the matrix-holding cylinder 3;
pushing, through the pushing means 8, the front end of the plate 1 in contact with the fixed hooking means 9 of the matrix-holding cylinder 3;
rotating (direction A) the matrix-holding cylinder 3 till the fixed hooking means 9 engage the front gripping edge 11 of the plate 1;
freeing the plate 1 from the pushing of the pushing means 8 engaged with the matrix-holding cylinder 3;
rotating (direction A) the matrix-holding cylinder 3 keeping the plate 1 in contact with its external surface through the pressing means 12;
opening, through the opening means 16, 18, 20, 22, 24, 26 controlled by the control means 28, 30, 32, the mobile hooking means 23 of the matrix-holding cylinder 3 when the cylinder 3 rotates;
after a 180° rotation (direction A) of the matrix-holding cylinder 3, placing the rear end of the plate 1 next to the opened mobile hooking means 23; and
closing the mobile hooking means 23 engaging the rear end of the plate 1 through the control means 28, 30, 32.

The above-describe process can further comprise, before the step of pushing the front end of the plate 1 in contact with the fixed hooking means 9 of the matrix-holding cylinder 3, the further step of attracting, through the attraction means 34, the front end in a position that is adapted to facilitate the following step of pushing.
Moreover, in the configuration where every matrix-holding cylinder 3 contains a plurality of matrix printing plates 1 on its external surface, and each one of the plates 1 comprises an identification code, the process further comprises the steps of:

programming a loading sequence of the plates 1 on the matrix-holding cylinder 3, in which such programmed sequence is stored in a central control and command unit, and in which the sequence establishes the identification code of the respective plate 1 to be placed in one of the foreseen positions on the matrix-holding cylinder 3;
automatically supplying the plurality of plates 1 onto the receiving and inserting means 7;
reading the identification code of each one of the plates 1 and coupling it with the identification code of the programmed sequence; and
loading each one of the plates 1 onto the matrix-holding cylinder 3 according to the programmed sequence contained in the central control and command unit.

With the same system, a process for automatically unloading matrix printing plates 1 from matrix-holding cylinders 3 is also realised, in which the following steps are substantially provided:

opening the mobile hooking means 23 of the matrix-holding cylinder 3 through the control means 28, 30, 32 disengaging the mobile hooking means 23 from the rear end of the plate 1;
through a rotation (direction B) of the matrix-holding cylinder 3, placing the rear end of the plate 1 above the end of the means 7 for receiving the plate 1;
through a further rotation (direction B) of the matrix-holding cylinder 3, sliding the plate 1 onto the receiving means 7 keeping the plate 1 in contact with the receiving means 7 on one hand, and in contact with the surface of the matrix-holding cylinder 3 on the other hand that has still not come in contact with the receiving means 7;
through a further rotation (direction B) of the matrix-holding cylinder 3 till a global rotation of 180° is performed, taking the recess in which the fixed hooking means 9 of the matrix-holding cylinder 3 are placed, and therefore the front end of the plate 1, in engagement with the fixed hooking means 9, next to the area in which the receiving means 7 are placed;
activating the strongly-attracting means 36 placed in the receiving means 7, so that the strongly-attracting means 36 attract the plate 1 against the receiving means 7 overcoming the pushing force exerted by the rotation of the matrix-holding cylinder 3: the plate 1 is kept in a fixed and unmoving position onto the receiving means 7 by the strongly-attracting means 36;
through a further rotation (direction B) of the matrix-holding cylinder 3, freeing the unmoving front end of the plate 1 from the engagement with the fixed hooking means 9; and
deactivating the strongly-attracting means 36 in order to allow removing the plate 1 from the receiving means 7.

The above-mentioned unloading process can also comprise, after the step of placing the rear end of the plate 1 above the end of the means 7 for receiving the plate 1, the further step of attracting, through the attraction means 34, the rear end of the plate 1 outside the recess in the matrix-holding cylinder 3 in which the mobile hooking means 23 are placed.
Also in this unloading process, in the configuration where every matrix-holding cylinder 3 is adapted to contain a plurality of matrix printing plates 1 on its external surface, and each of the plates 1 comprises an identification code, there are provided the further steps of:

programming a sequence of unloading of plates 1 from the matrix-holding cylinder 3, in which such programmed sequence is stored in a central control and command unit, and in which the sequence establishes the identification code of the respective plate 1 to be extracted from one of the provided positions on the matrix-holding cylinder 3; and
unloading each one of the plates 1 from the matrix-holding cylinder 3 on the receiving means 7 according to the programmed sequence contained in the central control and command unit.

With reference, finally, to Figures 13 to 36, the various detailed steps of the process of the invention are show, seen from two different operating positions. In particular, the various detailed operating steps are as follows:

angular positioning of the matrix-holding cylinder 3 for depositing plates (Fig. 13);
moving the rubber wheel 12 onto the cylinder 3 (Fig. 14);
manual depositing of plate one (Fig. 14);
starting the rotation of the matrix-holding cylinder 3 (Fig. 14);
actuating the piston 8 for plate one o.s. (operator side) (Fig. 15);
actuating the piston 8 for plate one o.s. (Fig. 16);
actuating the cam 28 on o.s. (Fig. 17);
actuating the piston 8 for plate one on transfer side (t.s.) (Fig. 18);
actuating the piston 8 for plate one t.s. (Fig. 19);
verifying position of cam 28 o.s. (Fig. 20);
actuating the cam 28 t.s. (Fig. 21);
actuating unlock of plate one o.s. (Fig. 22);
actuating unlock of plate two o.s. (Fig. 23);
actuating unlock of plate one o.s. (Fig. 24);
actuating unlock of plate two o.s. (Fig. 25);
verifying position of cam 28 t.s. (Fig. 26);
actuating the cam 28 o.s. (Fig. 27);
actuating unlock of plate three t.s. (Fig. 28);
actuating unlock of plate four t.s. (Fig. 29);
actuating unlock of plate three t.s. (Fig. 30);
actuating unlock of plate four t.s. (Fig. 31);
verifying position of cam 28 o.s. (Fig. 32);
actuating the cam 28 t.s. (Fig. 33);
verifying position of cam 28 t.s. (Fig. 34);
detaching the rubber wheel 12 from the matrix-holding cylinder 3 (Fig. 35); and
stopping the rotation of matrix-holding cylinder 3 (Fig. 36).

As can be seen by the Figures, the preferred embodiment deals with printing assemblies 5 in which there are four matrix-holding cylinders 3 to realise the four-colour printing. According to the position in which each cylinder 3 is placed, it has been necessary to arrange and place the respective frame 7 in mutually different positions and orientations, that all allowed the optimal use of the frame 7 for loading and unloading the plates 1: the optimum arrangement of the various frames 7 and cylinders 3 for the printing assembly with four cylinders 3 is the one shown in the drawings. It would obviously be possible to realise other mutual arrangements of frame 7 e cylinder 3 that obtain the same functionality, without departing from the scope of the invention, as pointed out by the enclosed Claims.

Claims

Process for automatically loading matrix printing plates (1) on matrix-holding cylinders (3) on printing assemblies (5) for rotary flexographic printing machines, comprising comprises the steps of:
- placing at least one matrix printing plate (1) on means (7) for receiving and inserting the plate (1) on the matrix-holding cylinder (3);

- slidingly advancing said plate (1) on said receiving and inserting means (7) till the front end of said plate (1) arrives at a coupling position with said matrix-holding cylinder (3);

characterised in that it further comprises the steps of:
- attracting, through attraction means (34), said front end in a position that is adapted to facilitate a following step of pushing, through pushing means (8), the front end of said plate (1) in contact with fixed hooking means (9) of said matrix-holding cylinder (3); rotating (direction A) said matrix-holding cylinder (3) till the fixed hooking means (9) engage the front gripping edge (11) of said plate (1);

- freeing said plate (1) from the pushing of said pushing means (8) engaged with the matrix-holding cylinder (3);

- rotating (direction A) the matrix-holding cylinder (3) keeping said plate (1) in contact with its external surface through pressing means (12);

- opening, through opening means (16, 18, 20, 22, 24, 26) controlled by control means (28, 30, 32), the mobile hooking means (23) of said matrix-holding cylinder (3) when said cylinder (3) rotates;

- after a 180° rotation (direction A) of said matrix-holding cylinder (3), placing the rear end of said plate (1) next to said opened mobile hooking means (23); and

- closing said mobile hooking means (23) engaging the rear end of said plate (1) through said control means (28, 30, 32).
Process according to Claim 1, wherein every matrix-holding cylinder (3) is adapted to contain a plurality of matrix printing plates (1) on its external surface, and each one of said plates (1) comprises an identification code, characterised in that it further comprises the steps of:
- programming a loading sequence of the plates (1) on the matrix-holding cylinder (3), said programmed sequence being stored in a central control and command unit, said sequence establishing the identification code of the respective plate (1) to be placed in one of the foreseen positions on the matrix-holding cylinder (3);

- automatically supplying the plurality of plates (1) onto said receiving and inserting means (7);

- reading the identification code of each one of said plates (1) and coupling it with the identification code of the programmed sequence; and

- loading each one of said plates (1) onto said matrix-holding cylinder (3) according to the programmed sequence contained in said central control and command unit.
Process for automatically unloading matrix printing plates (1) from matrix-holding cylinders (3) on printing assemblies (5) for rotary flexographic printing machines, characterised in that it comprises the steps of:
- opening the mobile hooking means (23) of said matrix-holding cylinder (3) through control means (28, 30, 32) disengaging said mobile hooking means (23) from the rear end of said plate (1);

- through a rotation (direction B) of said matrix-holding cylinder (3), placing the rear end of said plate (1) above an end of means (7) for receiving the plate (1);

- attracting, through attraction means (34), the rear end of said plate (1) outside the recess in said matrix-holding cylinder (3) in which said mobile hooking means (23) are placed;

- through a further rotation (direction B) of said matrix-holding cylinder (3), sliding said plate (1) onto said receiving means (7) keeping said plate (1) in contact with said receiving means (7) on one hand, and in contact with the surface of said matrix-holding cylinder (3) on the other hand, such surface having still not come in contact with said receiving means (7) ;

- through a further rotation (direction B) of said matrix-holding cylinder (3) till a global rotation of 180° is performed, taking the recess in which the fixed hooking means (9) of said matrix-holding cylinder (3) are placed, and therefore the front end of said plate (1) in engagement with said fixed hooking means (9), next to the area in which said receiving means (7) are placed;

- activating strongly-attracting means (36) placed in said receiving means (7), said strongly-attracting means (36) attracting said plate (1) against said receiving means (7) overcoming the pushing force exerted by the rotation of said matrix-holding cylinder (3), said plate (1) being kept in a fixed and unmoving position onto said receiving means (7) by said strongly-attracting means (36);

- through a further rotation (direction B) of said matrix-holding cylinder (3), freeing the unmoving front end of said plate (1) from the engagement with said fixed hooking means (9); and

- deactivating said strongly-attracting means (36) in order to allow removing said plate (1) from said receiving means (7).
Process according to Claim 3, wherein every matrix-holding cylinder (3) is adapted to contain a plurality of matrix printing plates (1) on its external surface, and each of said plates (1) comprises an identification code, characterised in that it further comprises the steps of:
- programming a sequence of unloading of plates (1) from the matrix-holding cylinder (3), said programmed sequence being stored in a central control and command unit, said sequence establishing the identification code of the respective plate (1) to be extracted from one of the provided positions on the matrix-holding cylinder (3); and

- unloading each one of said plates (1) from said matrix-holding cylinder (3) on said receiving means (7) according to the programmed sequence contained in said central control and command unit.
Process according to any one of the previous Claims, characterised in that said receiving and inserting means (7) are composed of a frame (7) that is extended for the whole longitudinal extension of said matrix-holding cylinder (3), said frame (7) being equipped with holding means (40) of said plates (1) against said frame (7) during their sliding movement on said frame (7), said frame (7) being further equipped with detecting means (42) for the position of said plates (1), said detecting means (42) being adapted to rotatingly control the matrix-holding cylinder (3) in order to phase its position with respect to the advancement of said plates (1) for their phased loading or unloading on or from said cylinder (3).
Process according to Claim 5, characterised in that said holding means (40) are composed of a plurality of magnets (40) and said detecting means (42) are composed of a plurality of sensors (42).
Process according to Claim 5 or 6, characterised in that said frame (7) is further equipped with rotating means (44) whose rolling action facilitates the displacement of said plates (1) on said frame (7).
Process according to any one of the previous Claims, characterised in that said rotating means (44) are composed of a plurality of rubber wheels (44).
Process according to any one of the previous Claims, characterised in that said pushing means (8) are composed of at least one piston (8).
Process according to any one of the previous Claims, characterised in that said pressing means (12) are composed of at least one rubber wheel (12).
Process according to any one of the previous Claims, characterised in that said attraction means (34) are composed of at least one magnet (34).
Process according to any one of the previous Claims, characterised in that said opening means (16, 18, 20, 22, 24, 26) are composed of a first and a second wheel (16, 18) adapted to roll onto the surface of said control means (28), said first and second wheels (16, 18) being respectively integral (through a junction 19) with a third and a fourth wheel (20, 22) adapted to control said mobile hooking means (23), said third and fourth wheels (20,22) being placed at an end of a respective toothed shaft (24, 26), said toothed shafts (24, 26) transferring the movement of the movable hooking means (23) from the wheels (16, 18, 20, 22) to the movable hooking means (23) themselves, said toothed shafts (24, 25) being mechanically connected to the movable hooking means (23).
Process according to any one of the previous Claims, characterised in that said control means (28, 30, 32) are composed of a cam (28) adapted to engage said first and second wheels (16, 18) during a rotation of said matrix-holding cylinder (3) in order to move said first and second wheels (16, 18) in an opening position of said mobile hooking means (23), said cam (28) being adapted to release the engagement of said first and second wheels (16, 18) during a further rotation of said matrix-holding cylinder (3) in order to snap said mobile hooking means (23) in engagement with the rear end of said plate (1), said cam (28) being adapted to assume a rest position, in which said cam (28) does not interfere with the rotation of said matrix-holding cylinder (3) and does not engage said first and second wheels (16, 18), said cam (28) assuming said rest position through the pull of elastic means (30), said cam (28) being adapted to further assume a working position, in which said cam (28) engages said first and/or second wheel (16, 18), said cam (28) assuming said working position through the thrust of piston means (32).
Process according to Claim 13, characterised in that said piston means (32) are adapted to move said cam (28) in three respective working positions, one in engagement with the first wheel (16) only, one in engagement with the second wheel (18) only and one in engagement both with the first wheel (16) and with the second wheel (18), to allow the engagement of three possible combinations of plates (1) on the matrix-holding cylinder (3).
Process according to any one of the previous Claims, characterised in that said strongly-attracting means (36) are composed of at least one electromagnet (36).
Process according to any one of the previous Claims, characterised in that the loading direction (A) has a rotation direction that is opposite with respect to the one of the unloading direction (B).
Process according to any one of the previous Claims, characterised in that every matrix-holding cylinder (3) contains eight matrix printing plates (1) mutually placed side by side on its external surface.
System for automatically loading and unloading matrix printing plates (1) from matrix-holding cylinders (3) on and from printing assemblies (5) for rotary flexographic printing machines, comprising:
- means (7) for receiving and inserting the plate (1) on the matrix-holding cylinder (3);

- fixed hooking means (9) for said matrix-holding cylinder (3), said fixed hooking means (9) being adapted to hook the front end of the plate (1) placed on said means (7) and being advanced till it engages said fixed hooking means (9);

characterised in that it further comprises:
- attracting means (34) for attracting the front end of said plate (1) in a position adapted to facilitate its supply on said matrix-holding cylinder (3) or its supply on said receiving means (7);

- pushing means (8) adapted to push said plate (1) to engage said fixed hooking means (9);

- pressing means (12) for keeping said plate (1) in contact with the external surface of said matrix-holding cylinder (3) during its rotation;

- opening means (16, 18, 20, 22, 24, 26), controlled by control means (28, 30, 32), adapted to open the mobile hooking means (23) of said matrix-holding cylinder (3) during a first rotation of said cylinder (3) to place thereon the rear end of said plate (1), and adapted to close the mobile hooking means (23) in gripping engagement with the rear end of said plate (1).
System according to Claim 18, wherein every matrix-holding cylinder (3) is adapted to contain a plurality of matrix printing plates (1) on its external surface, and each one of said plates (1) comprises an identification code, characterised in that it further comprises:
- means for programming a loading sequence of the plates (1) on the matrix-holding cylinder (3), said programmed sequence being stored in a central control and command unit, said sequence establishing the identification code of the respective plate (1) to be placed in one of the foreseen positions on the matrix-holding cylinder (3);

- means for automatically supplying the plurality of plates (1) onto said receiving and inserting means (7);

- means for reading the identification code of each one of said plates (1) and coupling it with the identification code of the programmed sequence; and

- means for loading each one of said plates (1) onto said matrix-holding cylinder (3) according to the programmed sequence contained in said central control and command unit.
System according to Claims 18 or 19, characterised in that it further comprises strongly-attracting means (36) placed in said receiving means (7), said strongly-attracting means (36) attracting said plate (1) against said receiving means (7) by overcoming the thrust force provided by the rotation of said matrix-holding cylinder (3), said plate (1) being kept in a fixed and unmoving position on said receiving means (7) by said strongly-attracting means (36) to realise the final unloading of said plate (1) from said cylinder (3).
System according to any one of Claims 18 to 20, wherein every matrix-holding cylinder (3) is adapted to contain a plurality of matrix printing plates (1) on its external surface, and each of said plates (1) comprises an identification code, characterised in that it further comprises:
- means for programming a sequence of unloading of plates (1) from the matrix-holding cylinder (3), said programmed sequence being stored in a central control and command unit, said sequence establishing the identification code of the respective plate (1) to be extracted from one of the provided positions on the matrix-holding cylinder (3); and

- means for unloading each one of said plates (1) from said matrix-holding cylinder (3) on said receiving means (7) according to the programmed sequence contained in said central control and command unit.
System according to any one of Claims 18 to 21, characterised in that said receiving and inserting means (7) are composed of a frame (7) that is extended for the whole longitudinal extension of said matrix-holding cylinder (3), said frame (7) being equipped with holding means (40) of said plates (1) against said frame (7) during their sliding movement on said frame (7), said frame (7) being further equipped with detecting means (42) for the position of said plates (1), said detecting means (42) being adapted to rotatingly control the matrix-holding cylinder (3) in order to phase its position with respect to the advancement of said plates (1) for their phased loading or unloading on or from said cylinder (3).
System according to Claim 22, characterised in that said holding means (40) are composed of a plurality of magnets (40) and said detecting means (42) are composed of a plurality of sensors (42).
System according to Claim 22 or 23, characterised in that said frame (7) is further equipped with rotating means (44) whose rolling action facilitates the displacement of said plates (1) on said frame (7).
System according to any one of Claims 18 to 24, characterised in that said rotating means (44) are composed of a plurality of rubber wheels (44).
System according to any one of Claims 18 to 25, characterised in that said pushing means (8) are composed of at least one piston (8).
System according to any one of Claims 18 to 26, characterised in that said pressing means (12) are composed of at least one rubber wheel (12).
System according to any one of Claims 18 to 27, characterised in that said attracting means (34) are composed of at least one magnet (34).
System according to any one of Claims 18 to 28, characterised in that said opening means (16, 18, 20, 22, 24, 26) are composed of a first and a second wheel (16, 18) adapted to roll onto the surface of said control means (28), said first and second wheels (16, 18) being respectively integral (through a junction 19) with a third and a fourth wheel (20, 22) adapted to control said mobile hooking means (23), said third and fourth wheels (20,22) being placed at an end of a respective toothed shaft (24, 26), said toothed shafts (24, 26) transferring the movement of the movable hooking means (23) from the wheels (16, 18, 20, 22) to the movable hooking means (23) themselves, said toothed shafts (24, 25) being mechanically connected to the movable hooking means (23).
System according to any one of Claims 18 to 29, characterised in that said control means (28, 30, 32) are composed of a cam (28) adapted to engage said first and second wheels (16, 18) during a rotation of said matrix-holding cylinder (3) in order to move said first and second wheels (16, 18) in an opening position of said mobile hooking means (23), said cam (28) being adapted to release the engagement of said first and second wheels (16, 18) during a further rotation of said matrix-holding cylinder (3) in order to snap said mobile hooking means (23) in engagement with the rear end of said plate (1), said cam (28) being adapted to assume a rest position, in which said cam (28) does not interfere with the rotation of said matrix-holding cylinder (3) and does not engage said first and second wheels (16, 18), said cam (28) assuming said rest position through the pull of elastic means (30), said cam (28) being adapted to further assume a working position, in which said cam (28) engages said first and/or second wheel (16, 18), said cam (28) assuming said working position through the thrust of piston means (32).
System according to Claim 32, characterised in that said piston means (32) are adapted to move said cam (28) in three respective working positions, one in engagement with the first wheel (16) only, one in engagement with the second wheel (18) only and one in engagement both with the first wheel (16) and with the second wheel (18), to allow the engagement of three possible combinations of plates (1) on the matrix-holding cylinder (3).
System according to any one of Claims 18 to 31, characterised in that said strongly-attracting means (36) are composed of at least one electromagnet (36).
System according to any one of Claims 18 to 32, characterised in that the loading direction (A) has a rotation direction that is opposite with respect to the one of the unloading direction (B).
System according to any one of Claims 18 to 33, characterised in that every matrix-holding cylinder (3) contains eight matrix printing plates (1) mutually placed side by side on its external surface.