Method for setting the printing format distance in a variable printing format offset printing unit, variable format offset printing unit, printing machine, cam, cam kit

Abstract

The subject matter of the present invention is a method for setting a printing format distance D in a printing unit 1 of the offset type with variable printing format for a printing machine of the offset type with variable printing format 100, comprising a first cylinder 3, 3' rotatable around a first rotation axis X1 and a second cylinder 4, 4' rotatable around a second rotation axis X2, wherein the second cylinder 4, 4' is supported in oscillation by at least one oscillating lever 11, 11' pivoted on an oscillation axis X4, such that the second rotation axis X2 is movable along a circular trajectory centred on the oscillation axis X4 in order to bring the first cylinder and the second cylinder closer together or further apart, wherein the method comprises the steps of: a) providing at least one cam 6, 6', wherein the at least one cam 6 is configured to be interposed, directly or indirectly, between the first cylinder 3, 3' and the second cylinder 4, 4' so as to form a structural constraint that prevents the rotation of each oscillating lever 11, 11 ' towards the first axis X1 when each oscillating lever 11, 11' is in the second angular position, uniquely defining the printing format distance D between the second axis X2 of the second cylinder 4, 4' and the first axis X1 of the first cylinder 3, 3'; wherein, when each oscillating lever 11, 11' is in the first angular position, the method comprises the steps of: b) connecting the at least one cam 6, directly or indirectly, to the first cylinder 3, 3', and c) orienting the at least one cam 6 by arranging it along the circular trajectory along which the second axis X2 is movable, wherein, once the at least one cam 6 has been connected and oriented, the method comprises the step of: d) rotating each oscillating lever 11, 11 ' supporting the second cylinder 4, 4', from the first angular position towards at least one second angular position, moving the second axis X2 along the circular trajectory towards the first axis X1, until the cam 6 is tightened and interposed between the first cylinder 3, 3' and the second cylinder 4, 4', wherein, when the at least one cam 6 is tightened and interposed between the first cylinder 3, 3' and the second cylinder 4, 4', the at least one cam 6 forms a structural constraint that prevents the rotation of each oscillating lever 11, 11 ' towards the first axis X1, stopping and / or blocking each oscillating lever 11, 11 ' in at least one second angular position and uniquely defining the printing format distance D between the second axis X2 of the second cylinder 4, 4' and the first axis X1 of the first cylinder 3, 3'.

Description

"Method for setting the printing format distance in a variable printing format offset printing unit, variable format offset printing unit, printing machine, cam, cam kit”***DESCRIPTION

[0001] . Field of the invention

[0002] . The present invention relates to a method for setting the print format distance in a variable print format offset type printing unit, as well as to a variable print format offset type printing unit configured to be used on so-called offset type printing machies, and in particular on variable print format offset type printing machines, as well as to a printing machine, as well as to a cam configured to uniquely define or set the print format distance, as well as to a kit of cams which can be alternately mounted in the printing unit so as to set different print format distances based on the diameter of the plate cylinder and of the transfer or blanket cylinder which are mounted in the printing unit.

[0003] . Prior art

[0004] . In the field of offset type printing machines, the use is known of at least one variable format offset printing unit comprising three rotating cylinders whose axes are horizontally oriented. The first cylinder, commonly referred to as plate cylinder, carries wrapped around it a printing plate intended to transfer, through printing patterns, the ink received from a series of inking rollers. The second cylinder, commonly referred to as intermediate or transfer cylinder, is coated with elastomeric material, such as for example rubber, and is arranged in contact with the plate cylinder. The third cylinder, commonly known as impression cylinder, is placed in contact with the rubber cylinder. The paper web or other printable material is passed between the intermediate cylinder and the impression cylinder. During operation, the intermediate cylinder receives the ink from the plate cylinder by means of printing patterns that compose the printed image and transfers the ink onto the web advanced between the intermediate cylinder and the impression cylinder.

[0005] . A pair of cylinders composed of a plate cylinder and an intermediate cylinder having the same diameter is referred to as print format. To vary the print length it is necessary to vary the diameter of the plate cylinder and of the intermediate cylinder and therefore also to vary the distance between the axes of the three cylinders. Variable format offset printing units are therefore provided, in a known manner, with mechanisms for adjusting the distance between the cylinders that allow, in the case of variation of the cylinder diameters, in particular of the plate cylinder and of the intermediate cylinder (which form the print format and determine the print length), to appropriately vary the distance between the cylinders so as to ensure contact between the intermediate cylinder and the plate cylinder on the one hand and between the intermediate cylinder and the impression cylinder on the other. In order to ensure that the printing process takes place correctly, it is also necessary to maintain a certain contact pressure between the cylinders of the printing unit in contact with each other, that is,both between the intermediate cylinder and the plate cylinder and between the intermediate cylinder and the impression cylinder.

[0006] . A solution of a printing unit of this type is known from document EP2388141 , in which the plate cylinder is interchangeable to change the print format, in which each plate cylinder is connectable to a bearing having a fixed position of the axis of rotation, in which the transfer cylinder is interchangeable to change the print format, in which each transfer cylinder is connectable to a rotation support coupled to one end of a lever actuable in rotation by actuation and positioning means to support the transfer cylinder and position the axis of rotation of the transfer cylinder, and in which the impression cylinder is mounted on an eccentric bearing so as to be positionable and lockable in a plurality of axis-of-rotation positions.

[0007] . In this solution, with each change of print format the positioning lever of the transfer cylinder moves to a change position moving away from the plate cylinder, and the inking cylinders are also moved to a respective change position moving away from the plate cylinder, to allow replacement of the plate cylinder and of the transfer cylinder with a plate cylinder of different format and a transfer cylinder of different format. Once the plate cylinder of different format has been connected and locked to the respective plate cylinder support and once the transfer cylinder of new format has been connected and locked to the respective transfer cylinder support, the positioning lever must be moved to position and lock the axis of rotation of the transfer cylinder with respect to the axis of rotation of the plate cylinder at a correct print format distance. Likewise, the inking cylinders must also be moved to position and lock their respective axes of rotation of the inking cylinders with respect to the axis of the plate cylinder at a correct print format distance.

[0008] . In this known solution, the correct positioning of the transfer cylinder must be carefully checked, and must be maintained at the correct print format distance for the entire required duration of the printing. This on the one hand requires a high degree of operator attention to position the transfer cylinder in the correct printing position, or expensive automated adjustment means comprising positioning motors, for example with screw-nut systems, preferably with ball recirculation, and on the other hand it may happen that the distance between the axis of the plate cylinder and the axis of the transfer cylinder may undergo slight variations during the printing time, for example due to vibrations or due to wear of the screw-nut system, which can lead to printing defects, making it necessary to further adjust the position of the transfer cylinder by the operator, with consequent machine stoppage and production slowdowns.

[0009] . Therefore, in the sector there is a strong need to provide a method for adjusting or setting the print format distance in a unit, as well as to make a variable format offset printing unit that allows to position the transfer cylinder at the correct print format distance from the plate cylinder, avoiding or reducing the risk of movement of the transfer cylinder during printing operations, in asimplified manner and easily integrable also in known type printing units, reducing the risk of machine stoppages and of operator interventions to adjust the position of the transfer cylinder several times.

[0010] . Therefore, in the sector, there is a need to provide a method for adjusting or setting a print format distance, as well as to provide a variable format offset printing unit that allows to reduce the intervention time to position the cylinders at the correct distance from each other at each format change, reducing or avoiding any interventions of the operator once the correct distance between the plate cylinder and the transfer cylinder has been set.

[0011] . Solution

[0012] . The objective of the present invention is to provide a method for setting the print format distance in a variable format offset printing unit, as well as a variable format offset printing unit, as well as a printing machine, as well as a cam, as well as a kit of cams.

[0013] . This and other objects and advantages are achieved with a method for adjusting a print format distance in a variable format offset printing unit, as well as a variable format offset printing unit, as well as a printing machine, as well as a cam, as well as a kit of cams according to the independent claims.

[0014] . Some advantageous embodiments are the subject of the dependent claims.

[0015] . From the analysis of this solution it has emerged that the proposed solution allows to uniquely set the print format distance between the first cylinder or plate cylinder and the second cylinder or transfer cylinder, based on the selected print format, in reduced time and without the need for adjustment of the position of the first cylinder and of the second cylinder over time.

[0016] . Furthermore, the proposed solution allows to make a structural and interchangeable constraint that enables maintaining the correct distance between the first cylinder and the second cylinder over time without risks of movement of the first cylinder or of the second cylinder during the printing operations.

[0017] . Moreover, the proposed solutions allow to interpose a shaped element between the first cylinder and the second cylinder, in an interchangeable way depending on the diameter of the print format of the first cylinder and of the second cylinder, defining a unique assembly configuration in which the distance between the first cylinder and the second cylinder for the selected print format is uniquely and error-proof set.

[0018] . Thanks to the proposed solutions, the setting of the print format distance is achieved by means of a physical element, namely the cam, which is positioned on the first cylinder or on its support and clamped in abutment with the second cylinder or one of its supports, by moving the second cylinder towards the first cylinder. In other words, the cam defines a mechanical stop for positioning the second cylinder with respect to the first cylinder during the abutment of the second cylinder towards the first cylinder, which defines the end-of-stroke position of the abutment movementachieved by thrust means, such as hydraulic or pneumatic thrust, which actuate the oscillating levers supporting the second cylinder and allowing its movement towards or away from the first cylinder along a circular trajectory. Consequently, thanks to this solution, numerical control over time of the position of the oscillating levers and of the second cylinder with respect to the first cylinder is avoided, as the distance between the axis of the first cylinder and the axis of the second cylinder is set and determined by the cam, and once the cam is clamped, the print format distance between the axis of the first cylinder and the axis of the second cylinder is automatically determined, without the need to check the position of the second cylinder or of the levers supporting it.

[0019] . Furthermore, thanks to the proposed solutions, it is possible to ensure a safe, durable, and resistant positioning, free from mechanical play, between the first cylinder and the second cylinder and between the inking cylinders and the first cylinder with a single shaped interchangeable element depending on the selected print format interposed between the first cylinder and the second cylinder and between the first cylinder and the inking cylinders.

[0020] . Figures

[0021] . Further features and advantages of the method, of the variable format offset printing unit for a variable format offset printing machine will appear from the following description of its preferred embodiments, given by way of non-limiting example, with reference to the attached figures in which:

[0022] . - Figure 1 shows a side view of a printing machine comprising a variable format offset printing unit according to the present invention, in which a first cylinder or plate cylinder and a second cylinder or transfer cylinder having a first format diameter are mounted in the printing unit, wherein the printing unit is set for a first printing dimension or first print format distance, wherein the minimum distance between the axis of the first cylinder or plate cylinder and the axis of the second cylinder or intermediate or transfer cylinder is set by a cam or first format cam, for example the first format cam may be part of a kit of cams interchangeably mountable on the printing unit according to the print format and therefore according to the diameters of the first mounted cylinder and second mounted cylinder;

[0023] . - Figure 2 shows a side view of the printing unit of figure 1 wherein the actuators for moving the inking cylinder unit and the oscillating lever of the second cylinder have been omitted, and also the locking levers and the locking / unlocking elements for replacing the first cylinder and the second cylinder have been omitted, so as to highlight the first format cam configured to be mounted between the first cylinder and the second cylinder having a first format diameter uniquely defining their distance during printing between the two cylinders for first dimension printing;

[0024] . - Figure 3 shows a printing machine comprising a variable format offset printing unit according to the present invention, in which the printing unit shown in figure 1 is set for a secondprinting dimension, in which the first cylinder and the second cylinder are replaced with respective cylinders for a second printing dimension or second print format distance and having a second format diameter, in which the second format diameter is greater than the first format diameter, in which the first format cam of figure 1 is replaced by a further cam or second format cam, in which the minimum distance between the first cylinder and the second cylinder is set by the second format cam, and in which the second format cam defines a mechanical end stop setting the angular position of the oscillating lever of the second cylinder during printing, in which the second printing dimension is greater than the first printing dimension, in which the second print format cam may be part of the interchangeable cam kit;

[0025] . - Figure 4 shows a side view of the printing unit of figure 3 wherein the actuators for moving the inking cylinder unit and the oscillating lever of the second cylinder have been omitted, and also the locking levers and the locking / unlocking elements for replacing the first cylinder and the second cylinder have been omitted, so as to highlight the second format cam configured to be mounted between the first cylinder and the second cylinder uniquely defining their distance for printing in the second printing dimension;

[0026] . - Figure 5 shows a side view of the printing unit of figure 3, wherein some elements are omitted to better highlight others, wherein the oscillating lever of the second cylinder is in a print format change position and the first cylinder and the second cylinder are spaced apart and not adjacent to each other, wherein the locking lever of the first cylinder and the locking lever of the second cylinder are arranged rotated around their respective axis in a cylinder change position, avoiding interference with the removal of the first cylinder and the second cylinder in order to replace them for a print format change, wherein the print format cam is connected to the first cylinder support connected to the locking lever of the first cylinder, wherein the inking cylinder unit is positioned spaced from the first cylinder to allow cylinder replacement;

[0027] . - Figure 6 schematically shows an axonometric view, , of the printing unit of figure 5, wherein the actuator for rotating the articulation lever is visible, wherein the support of the first cylinder and the support of the second cylinder are translated into a position away from the cylinders in a step of insertion or replacement of the cam according to the print format that defines the distance between the pair of the first cylinder and the second cylinder for the specific printing dimension, wherein the cam is mounted with the support of the first cylinder abutting thereon with a first positioning seat of the cam, and wherein the cam is oriented in a mounting position such that, once the support of the first cylinder and the support of the second cylinder are translated towards the respective cylinders, by rotating the oscillating lever of the second cylinder, the distance between the two cylinders is uniquely determined as soon as the support of the second cylinder abuts with a second positioning seat of the cam;

[0028] . - Figure 7 schematically shows a side view, , of the printing unit of figures 5 and 6, wherein the oscillating lever of the second cylinder and the locking levers of the pair of rollers are omitted with respect to figure 6, wherein the cam is uniquely mounted between the first cylinder, the second cylinder and the at least one inking cylinder;

[0029] . - Figure 8 schematically shows an axonometric view, , of the printing unit of figure 7, wherein a part of the frame and the actuator of the inking cylinder unit is omitted with respect to figure 7, so as to show the cam inserted in its unique position between the first cylinder and the second cylinder for the specific print format, wherein the inking cylinder unit is positioned uniquely at the correct distance from the first cylinder thanks to the abutment between the inking cylinder unit and a third positioning seat of the cam;

[0030] . - Figure 9 shows a front view of the printing unit of figure 6, wherein the translation of the locking lever of the first cylinder is schematically shown, to which a first cam or left-hand cam may be connected, wherein a second cam or right-hand cam positioned between the first cylinder and the second cylinder is also shown;

[0031] . - Figure 10 shows schematically in a perspective view the right-hand and left-hand positioning levers comprising the second cylinder supports, the first cylinder supports, and two cams configured to be interposed and clamped, right-hand and left-hand, between the first cylinder supports and the second cylinder supports, wherein a positioning lever comprises the second cylinder support rotatably connected to one end of the lever, and wherein the other positioning lever comprises the second cylinder support made enbloc at one of its ends, wherein one first cylinder support is fixedly connected to the support structure and the other first cylinder support is rotatably connected to the support structure, wherein the abutment portions of the cams with the counter-coupling portions of the first cylinder supports and the second cylinder supports are visible.

[0032] . - Figure 11 shows, schematically in a second perspective view, the right-hand and lefthand positioning levers comprising the second cylinder supports, the first cylinder supports, and the two cams of figure 10;

[0033] . - Figures 12A and 12B show in perspective view the printing unit according to the present invention reversibly connectable to the printing machine according to the present invention;

[0034] . - Figure 13 shows in a first perspective view a cam according to the present invention, or first format cam for a first print format, wherein the cam depicted may be a first format cam of the cam kit, usable in a printing unit in which the first cylinder and the second cylinder having the first format diameter are mounted;

[0035] . - Figure 14 shows in a second perspective view the cam of figure 13;

[0036] . - Figure 15 shows in a first perspective view a cam according to the present invention, or second format cam for a second print format, wherein the cam depicted may be a second formatcam of the cam kit, usable in a printing unit in which the first cylinder and the second cylinder having the second format diameter are mounted;

[0037] . - Figure 16 shows in a second perspective view the cam of figure 15;

[0038] . - Figure 17 shows the first format cam of figures 13 and 14, wherein an exploded view of an elastic locking device is shown, wherein the elastic locking device is housed in an orientation fixing seat, made as a hole or pair of holes, wherein the elastic locking device is configured to elastically retain a positioning pin in the orientation fixing seat, wherein the positioning pin is connected to the support structure of the printing unit so as to elastically and reversibly lock the axial position of the cam along the direction parallel to the first axis when the cam is mounted in the printing unit, and also to lock the orientation of the cam when the cam is mounted with its first positioning seat on the respective first cylinder support;

[0039] . - Figure 18 shows the second format cam of figures 15 and 16, wherein an exploded view is shown, similarly to figure 17, of the elastic locking device, wherein the elastic locking device comprises an interference element, made as a ball, and an elastic element, wherein the interference element is movable between a retracted position and a maximum interference position, wherein the interference element is constantly urged towards the maximum interference position by the elastic element;

[0040] . - Figure 19 shows the left-hand first cylinder support to which the cam can be connected, wherein the left-hand first cylinder support comprises a left-hand positioning pin which extends along an axis parallel to the first axis of the first cylinder, wherein the left-hand positioning pin is configured to be inserted into an orientation fixing seat formed on the body of a left-hand cam, to be mounted on the printing unit;

[0041] . - Figure 20 shows a right shoulder of the support structure of the printing unit, wherein the right-hand first cylinder support is rigidly connected to the right shoulder and wherein a right-hand positioning pin is rigidly connected to the right shoulder, wherein the right-hand positioning pin is configured to be inserted into an orientation fixing seat formed on the body of a right-hand cam to be mounted on the printing unit;

[0042] . - Figure 21 shows a right-hand perspective view, partially, of the printing unit according to the present invention, wherein the first cylinder or first roller is visible, on which the sleeve of the first cylinder is mountable, mounted on the respective first cylinder supports so as to be rotatable about the first axis, wherein the right-hand cam and the left-hand cam are visible mounted on the right-hand first cylinder support and on the left-hand first cylinder support, wherein the orientation of the cams is uniquely set by the insertion of the right-hand positioning pin and of the left-hand positioning pin into the respective orientation fixing seats formed in the body of the right-hand cam and in the body of the left-hand cam;

[0043] . - Figure 22 shows a left-hand perspective view, partially, of the printing unit of figure21 ;

[0044] . - Figure 23 shows a three-dimensional front view, partially, of the printing unit according to the present invention, wherein the cam according to the present invention is shown in transparency to show the connection to the printing unit which enables uniquely determined positioning and orientation, wherein the cam is connected to the left-hand first cylinder support with a first positioning seat of the cam, wherein the first positioning seat is a through-hole which shape-fits with a counter-shaped portion of the left-hand first cylinder support, and wherein the cam is connected to the left-hand positioning pin by receiving it in its orientation fixing seat, wherein the elastic locking device is visible with the interference element elastically urged towards the maximum interference position and housed in a groove of the left-hand positioning pin, so as to uniquely set the orientation of the cam around the first axis and to set an axial position of the cam;

[0045] . Figure 24 shows a perspective view, partially, of the printing unit according to the present invention shown in figure 23.

[0046] . Detailed description of some preferred embodiments

[0047] . In accordance with a general embodiment, a variable format offset printing unit or printing unit for a variable format offset printing machine 100 is provided, generally indicated with reference number 1 .

[0048] . The printing unit 1 comprises a support structure 2. For example, the support structure comprises a frame comprising a right-hand wall or shoulder and an opposite left-hand wall or shoulder spaced from each other along an axial direction.

[0049] . The printing unit 1 comprises a first cylinder or plate cylinder 3, replaceable and supported in rotation by the support structure 2 about a first axis X1 . The first axis X1 is movable or stationary with respect to the support structure 2. The first cylinder 3 is supported at its opposite ends by respective first cylinder supports 9, 9’ connected to the support structure 2. In one embodiment, the respective first cylinder supports 9, 9’ are positionable with respect to the support structure 2 in a single axial position so as to make the first axis X1 stationary. In one embodiment, the first cylinder 3 is made in the form of a replaceable sleeve. In one embodiment, at least one or both of the respective first cylinder supports 9, 9’ are configured to adjust the axial position of the first axis X1 with respect to the support structure, for example wherein the respective first cylinder supports 9, 9’ comprise respective eccentric bearings. In accordance with one embodiment, when in use, the first axis X1 , if movable by means of adjustment devices, is fixed to the support structure 2.

[0050] . The printing unit 1 comprises a second cylinder or transfer cylinder 4, replaceable and supported in rotation about a second axis X2. The second axis X2 is preferably parallel to the first axisX1 . In one embodiment, the second axis X2 is inclined by an angle less than 10°, preferably less than 2° with respect to the first axis X1 .

[0051] . The second cylinder 4 is supported at its opposite ends by respective second cylinder supports 10, 10’, wherein at least one of the respective second cylinder supports 10, 10’ is supported by a respective oscillating lever 11 , 1 T. In one embodiment, both second cylinder supports 10, 10’ are supported by respective oscillating levers 11 , 11’, one on the right-hand side and one on the left-hand side, opposite and axially spaced from each other, and connected to each other by a lever connecting rod or lever synchronization rod 33 so as to oscillate synchronously.

[0052] . Each oscillating lever 11, 1 T is connected to the support structure 2 in rotation about an oscillation axis X4 parallel to the second axis X2 such that the second axis X2 is movable along a circular trajectory centred on the oscillation axis X4 to be positioned at a print format distance D from the first axis X1 . The print format distance D is variable depending on the selected print format, that is, on the diameters of the selected cylinder pair, the first cylinder 3 and the second cylinder 4. In one embodiment, the correct print format distance D depends on and / or varies interchangeably based on the print format defined by the pair of the first cylinder 3 and the second cylinder 4. Thanks to the rotatable support of the respective oscillating lever 11 , 11’, the second cylinder supports 10, 10’ are positionable along the circular trajectory and consequently the second axis X2 is positionable along the circular trajectory at the correct print format distance D.

[0053] . According to one aspect, each oscillating lever 11 , 1 T is pivoted to the support structure 2 in rotation about an oscillation axis X4 between a first angular position or format change angular position and a second angular position or print format angular position, and vice versa, such that when the second cylinder 4, 4’ is supported by the pair of second cylinder supports 10, 10’, the second axis X2 is movable along a circular trajectory centred on the oscillation axis X4, wherein the oscillation axis X4 is parallel to the second axis X2, wherein the oscillation axis X4 is stationary and fixed relative to the support structure 2.

[0054] . When each oscillating lever 11 , 1 T is in the second angular position, the second axis X2 is positioned at the print format distance D from the first axis X1 for printing on a material.

[0055] . When each oscillating lever 11 , 1 T is in the first angular position, the first cylinder 3 and the second cylinder 4 are spaced apart such that the second cylinder 4 and the first cylinder 3 can be separated from their respective first cylinder supports 10, 10’ and from their respective second cylinder supports 11, 1 T and replaced to vary the print format. In one embodiment, the first cylinder 3 and the second cylinder 4 are independently motorised from one another. In one embodiment, the printing unit 1 avoids including connection transmissions to rotate the first cylinder 3 and the second cylinder 4, for example with a single motor.

[0056] . The printing unit 1 comprises a third cylinder or impression cylinder 5, supported inrotation by the support structure 2 about a third axis X3. The third axis X3 is preferably parallel to the first axis X1 and to the second axis X2. The third cylinder 5 is supported at its axial ends by respective third cylinder supports 21 , 2T. In one embodiment, the third cylinder supports 21 , 2T are configured to move the third axis X3 relative to the first axis X1 and to the second axis X2 so as to select a third axis position to achieve a desired contact pressure between the third and the second cylinder. In one embodiment, the third cylinder supports 21, 2T are eccentric, for example eccentric bearings. In one embodiment, the third cylinder supports 21, 2T are linear, for example linear guides. As known, the sheet, for example of paper or plastic film, to be printed, passes between the second cylinder and the third cylinder. In one embodiment, when in use, the position of the third axis X3 is fixed. In one embodiment, the third axis X3 is inclined by an angle less than 10°, preferably less than 2°, with respect to the first axis X1 .

[0057] . The printing unit 1 comprises at least one cam or shaped element 6 configured to uniquely set or define the print format distance D between the second axis X2 of the second cylinder 4 and the first axis X1 of the first cylinder 3.

[0058] . The at least one cam 6, 6’ is connected to the first cylinder 3 or to one of the first cylinder supports 9, 9’, projecting in a cantilevered manner, directly or indirectly, from the first cylinder 3, wherein the at least one cam 6, 6’ is oriented and arranged along the circular trajectory along which the second axis X2 is movable when the second cylinder 4 is supported by each oscillating lever 11 , 11’, so as to form a structural constraint that intercepts, directly or indirectly, the second cylinder 4 during rotation of each oscillating lever 11, 1 T towards the first axis X1 from the respective first angular position, stopping and / or locking each oscillating lever 11 , 1 T in the second angular position and uniquely defining the print format distance D between the second axis X2 of the second cylinder 4 and the first axis X1 of the first cylinder 3.

[0059] . When each oscillating lever 11, 1 T is in the second angular position supporting the second cylinder 4, the at least one cam 6 is clamped and interposed, directly or indirectly, between the first cylinder 3 and the second cylinder 4 under a thrust action of each oscillating lever 11, 1 T, and the at least one cam 6 defines said structural constraint which prevents rotation of each oscillating lever 11 , 1 T towards the first axis X1, stopping and / or locking each oscillating lever 11 , 1 T in the second angular position.

[0060] . In one embodiment, when each oscillating lever 11 , 1 T is in the first angular position supporting the second cylinder 4, the at least one cam 6 is supported in a cantilevered manner by the first cylinder 3 or by one of the first cylinder supports 9, 9’ spaced from the second cylinder 4 and from the second cylinder supports 10, 10’.

[0061] . In one embodiment, when each oscillating lever 11 , 1 T is in the first angular position supporting the second cylinder 4, the at least one cam 6 is supported in a cantilevered manner by thefirst cylinder 3 or by one of the first cylinder supports 9, 9’, with a free space or gap present between the cam 6 and the second cylinder 4 and / or one of the second cylinder supports 10, 10’. The free space or gap extends between the cam 6 and the second axis X2 along a portion of the circular trajectory along which the second axis X2 is movable under the action of the oscillating levers. The free space or gap may be recovered until it is cancelled during the movement along the circular trajectory of the second axis X2 under the action of the oscillating levers towards the first axis X1 until the second cylinder 4 or one of the second cylinder supports 10, 10’ abuts against the cam 6.

[0062] . In one embodiment, when each oscillating lever 11 , 1 T is in the first angular position supporting the second cylinder 4, the at least one cam 6 is supported in a cantilevered manner by the first cylinder 3 or by one of the first cylinder supports 9, 9’ without interfering with the second cylinder 4 and / or with the second cylinder support 10, 10’, and / or without being in contact with the second cylinder 4 and / or with the second cylinder support 10, 10’.

[0063] . In one embodiment, the at least one cam 6, 6’ is reversibly connectable to the first cylinder 3 or to one of the first cylinder supports 9, 9’, to be replaceable according to the print format defined by the pair of the first cylinder and the second cylinder having the same diameter. In one embodiment, when each oscillating lever 11 , 1 T is in the second angular position supporting the second cylinder 4, at least one second cylinder support 10, 10’ is in abutment with the cam 6. In one embodiment, when each oscillating lever 11 , 1 T is in the second angular position supporting the second cylinder 4, each second cylinder support 10, 10’ is in abutment against a respective cam 6, 6’. In one embodiment, when each oscillating lever 11 , 1 T is in the first angular position supporting the second cylinder 4, the second cylinder support 10, 10’ is spaced from the cam 6. In one embodiment, when each oscillating lever 11 , 1 T is in the first angular position supporting the second cylinder 4, each second cylinder support 10, 10’ is spaced from the respective cam 6, 6’.

[0064] . In one embodiment, the printing unit 1 further comprises an inking unit 15. The inking unit 15 comprises at least one inking cylinder 16 supported in rotation about a respective inking cylinder axis X5 by respective inking cylinder supports 17, wherein each inking axis X5 is parallel to the first axis X1 . The inking unit 15 comprises thrust actuators configured to move the inking axis X5 towards or away from the first axis X1 . The at least one cam 6 is interposed, directly or indirectly, between the first cylinder 3 and each inking cylinder 16, without interfering with the rotation of the first cylinder 3 and of each inking cylinder 16 about respectively the first axis X1 and each respective inking cylinder axis X5.

[0065] . In one embodiment, the at least one cam 6 defines an abutment against which each inking cylinder 16 is, directly or indirectly, in abutment under a thrust action of said thrust actuators, which prevents the thrust actuators from further moving the inking axis X5 towards the first axis X1 , thus uniquely defining the relative position between the first axis X1 and each inking axis X5.

[0066] . In one embodiment, each oscillating lever 11 , 11’ is pivoted to the support structure 2 in rotation about said oscillation axis X4 at least between a first angular position and a second angular position, and vice versa.

[0067] . In one embodiment, each oscillating lever 11 , 11’ is configured to support the second cylinder 4 at least between the first angular position and the second angular position rotating towards the first axis X1 and moving the second axis X2 along said circular trajectory, wherein the cam 6 is configured to be connected, directly or indirectly, to the first cylinder 3, to be oriented along the circular trajectory along which the second axis X2 is movable, such that by rotating each oscillating lever 11 , 11’ supporting the second cylinder 4, from the first angular position towards the second angular position, the second axis X2 is moved along the circular trajectory towards the first axis X1 , until the cam 6 is clamped and interposed between the first cylinder 3 and the second cylinder 4 forming said structural constraint which prevents the rotation of each oscillating lever 11 , 11’ towards the first axis X1 , uniquely defining the print format distance D between the second axis X2 of the second cylinder 4 and the first axis X1 of the first cylinder 3.

[0068] . In one embodiment, the at least one cam 6 may be interposed, directly or indirectly, between the first cylinder 3 and the second cylinder 4, so as to form a structural constraint which prevents rotation of each oscillating lever 11 , 11’ at least towards the first axis X1, uniquely defining the print format distance D between the second axis X2 and the first axis X1 , avoiding interference with the rotation of the first cylinder 3 and the second cylinder 4 about the first axis X1 and the second axis X2 respectively, and avoiding steps of adjustment of the print format distance D.

[0069] . In one embodiment, the at least one cam 6 comprises a right-hand cam and a lefthand cam, as shown for example in figure 10. In accordance with one embodiment, the printing unit 1 comprises a pair of said at least one cam or shaped element 6, namely a right-hand cam 6 and a lefthand cam 6’ configured to be connected to the support structure 2 and / or to the first cylinder supports, from opposite axial sides.

[0070] . In one embodiment, the printing unit 1 comprises at least one lever thrust device 12 configured to push the at least one oscillating lever 11 , 11’ so as to move the second cylinder 4 and / or the second cylinder supports by clamping the at least one cam 6 or each cam 6, 6’ directly or indirectly between the first cylinder 3 and the second cylinder 4, and / or between the second cylinder supports and the first cylinder supports. In one embodiment, the printing unit 1 comprises one thrust device 12 for each oscillating lever 11, 11’ or one thrust device 12 for both oscillating levers 11 , 11’. Each thrust device 12 is configured to push the respective oscillating lever 11 , 11’ or both, so as to move the second cylinder 4 and / or the second cylinder supports by clamping each cam 6, 6’ directly or indirectly between the first cylinder 3 and the second cylinder 4. In one embodiment, each thrust device 12 is configured to constantly push the respective oscillating lever 11 , 11’ or both, clampingeach cam 6 directly or indirectly between the first cylinder 3 and the second cylinder 4, so as to constantly dissipate the vibrations due to the rotation and interaction between the first cylinder and the second cylinder on each cam 6, 6’. In one embodiment, each thrust device 12 is configured to constantly push the respective oscillating lever 11 , 11’, or both, clamping each cam 6 directly or indirectly between the first cylinder 3 and the second cylinder 4, so as to avoid or recover any mechanical play during the rotation of the first cylinder 3 and the second cylinder 4 due to discontinuities on the cylindrical surface of the first cylinder 3 and / or the second cylinder 4, during printing. In one embodiment, the second cylinder 4 is supported by pushing the lever thrust device 12.

[0071] . In one embodiment, each thrust device 12 is configured to apply a force greater than the printing load, between the first cylinder 3 and the second cylinder 4, necessary to achieve the correct preload on each cam 6, 6’. In one embodiment, each thrust device 12 is a pneumatic and / or hydraulic piston. In one embodiment, each thrust device 12 is configured to clamp each cam 6, 6’ between the first cylinder 3 and the second cylinder 4, or between their supports, avoiding including mechanical systems for transforming rotary motion into linear motion, such as screw-nut systems. In one embodiment, each thrust device 12 is configured to clamp each cam 6, 6’ between the first cylinder 3 and the second cylinder 4 avoiding the use of positioning motors.

[0072] . In one embodiment, the printing unit 1 comprises at least a plurality of the at least one cam 6, or a pair, interchangeable with each other for each print dimension D. For example, in figure 1 and figure 2 a cam or first format cam 6 is shown for a first print dimension D1 , compatible with a first cylinder and a second cylinder selected for the first print dimension D1 , whereas in figures 3 to 10 a cam or second format cam 6 is shown for a second print dimension D2, compatible with a first cylinder and a second cylinder selected for the second print dimension D2.

[0073] . Thanks to the solution of providing at least one shaped element, the cam 6, interchangeable depending on the print dimension D required for printing based on the diameters of the first cylinder 3 and the second cylinder 4, selected and mounted in the printing unit 1 , it is possible to define or uniquely set the distance between the first axis X1 and the second axis X2, without any need to provide a step of adjusting the position of the second cylinder to position it at the correct print distance, but simply by connecting the cam 6 directly or indirectly to the first cylinder 3 and orienting the cam so that by rotating each respective oscillating lever 11, 1 T the cam 6 is clamped directly or indirectly between stationary portions of the first cylinder 3 and the second cylinder 4, or between their first cylinder supports and second cylinder supports.

[0074] . In one embodiment, the printing unit 1 comprises each oscillating lever 11, 11’, each first cylinder support, each second cylinder support and each third cylinder support. In one embodiment, the respective first cylinder supports 9, 9’ are configured to rotatably support respective ends of the first cylinder 3, for example they are portions comprising radial bearings that rotatablysupport the first cylinder about the first axis X1 . In one embodiment, the second cylinder supports 10, 10’ are configured to rotatably support respective ends of the second cylinder 4, for example they are portions comprising radial bearings that rotatably support the second cylinder about the second axis X2.

[0075] . In one embodiment, the at least one cam 6 and / or each cam 6 comprises a first positioning seat 13 and a second positioning seat 14. In one embodiment, the at least one cam 6 comprises a shaped body that defines and / or delimits the first positioning seat 13 and the second positioning seat 14.

[0076] . In one embodiment, the first positioning seat 13 and the second positioning seat 14 are opposed to each other along a longitudinal cam direction perpendicular to the first axis X1 and the second axis X2. In one embodiment, the thickness of the shaped body is parallel to the first axis X1 and the second axis X2.

[0077] . In one embodiment, the at least one cam 6 is clamped in abutment between the first coupling portion 22 and the second coupling portion 23 received respectively in the first positioning seat 13 and in the second positioning seat 14, avoiding interference with the rotation of the first cylinder 3 and the second cylinder 4 about the first axis X1 and the second axis X2 respectively.

[0078] . In one embodiment, the respective first coupling portion 22 is a non-rotatable and stationary portion relative to the first axis X1 , once the first cylinder is mounted and constrained in the stationary position relative to the support structure 2.

[0079] . In one embodiment, the first cylinder 3 comprises the respective first coupling portion 22 at a stationary end portion of the first cylinder.

[0080] . In one embodiment, each of the respective first cylinder supports 9, 9’ comprises the respective first coupling portion 22.

[0081] . In one embodiment, the first cylinder 3 comprises the respective first coupling portion 22 at a stationary end portion of the first cylinder, so that the cam can be interposed directly against the first cylinder 3, against the stationary end portion of the first cylinder without interfering with the rotation of the first cylinder 3 about the first axis X1. In an alternative embodiment, each of the respective first cylinder supports 9, 9’ comprises the respective first coupling portion 22, wherein the respective first cylinder supports 9, 9’ are configured to rotatably support respective ends of the first cylinder 9, so that the cam 6 can be indirectly interposed against the first cylinder 3 through at least one of the respective first cylinder supports 9, 9’.

[0082] . In one embodiment, the second coupling portion 23 is a non-rotatable portion stationary with respect to the second axis X2, once the second cylinder is mounted and the position of the second cylinder relative to the support structure 2 is fixed.

[0083] . In one embodiment, the second cylinder 4 comprises the respective second couplingportion 23 at a stationary end portion of the second cylinder.

[0084] . In one embodiment, each of the second cylinder supports 10, 10' connected to the respective oscillating lever 11 , 11 ' comprises the respective second coupling portion 23.

[0085] . In one embodiment, the second cylinder 4 comprises the respective second coupling portion 23 at a stationary end portion of the second cylinder, so that the cam 6 can be interposed directly against the second cylinder 4, against its stationary end portion or the second cylinder, without interfering with the rotation of the second cylinder 4 about the second axis X2. Alternatively, in one embodiment, each of the second cylinder supports 10, 10', which are connected to the respective oscillating lever 11 , 11', comprises the respective second coupling portion 23, wherein the second cylinder supports 10, 10' are configured to rotatably support respective ends of the second cylinder 4, so that the cam 6 can be interposed indirectly against the second cylinder 4 by means of at least one of the respective second cylinder supports 10, 10'.

[0086] . In one embodiment, each first coupling portion 22 comprises a respective first cylindrical surface 24 that extends around a first coupling portion axis that is parallel and / or coaxial to the first axis X1 .

[0087] . In one embodiment, each second coupling portion 23 comprises a respective second cylindrical surface 25 that extends around a second coupling portion axis that is parallel and / or coaxial to the second axis X2.

[0088] . In one embodiment, the first positioning seat 13 comprises a first seat wall 19. The first seat wall 19 is at least semi-cylindrical and extends around a first seat axis that is parallel and / or coaxial to the first axis X1 so as to receive the respective first cylindrical surface 24 coaxial and / or parallel to the first axis X1 . In one embodiment, the first positioning seat 13 comprises the thickness of the shaped body of the cam extending around a first seat axis that is parallel and / or coaxial to the first axis X1 so as to receive the respective first cylindrical surface 24 coaxial and / or parallel to the first axis X1 . In one embodiment, the second positioning seat 14 comprises a second seat wall 20, wherein the second seat wall 20 is at least semi-cylindrical and extends around a second seat axis that is parallel and / or coaxial to the second axis X2 so as to receive the respective second cylindrical surface 25 parallel and / or coaxial to the second axis X2. In one embodiment, the second positioning seat 14 comprises the thickness of the shaped body of the cam extending around a second seat axis that is parallel and / or coaxial to the second axis X2 so as to receive the respective second cylindrical surface 25 parallel and / or coaxial to the second axis X2.

[0089] . The term "at least semi-cylindrical" refers to a curved or crescent-shaped surface that can receive the respective cylindrical surface by translation, forming an abutment along radial directions with respect to the first axis X1 or the second axis X2. In this way, the cam 6 can be inserted by translation in abutment against the first coupling portion and, by tightening the oscillatinglever 11 , 11 ' in abutment by translation against the second coupling portion. In one embodiment, the cam 6 comprises an elongated central cam portion that connects the first positioning seat and the second positioning seat.

[0090] . In one embodiment, the first seat wall 19 is cylindrical and defines a through hole coaxial to the first axis X1 , so that the respective first cylindrical surface 24 is insertable or can be fitted into the first positioning seat 13.

[0091] . In one embodiment, the second seat wall 20 is semi-cylindrical and concave, and / or subtends a central angle with respect to the second seat axis between 20° and 180°, preferably 90°, and is suitable to receive, for example by translation, the respective second cylindrical surface 25 coaxial to the second axis X2.

[0092] . In one embodiment, the first seat wall 19 has a first wall radius R1 greater than or equal to the first cylindrical surface radius r1 of the respective first cylindrical surface 24. In one embodiment, the second seat wall 20 has a second wall radius R2 greater than or equal to the second cylindrical surface radius r2 of the respective second cylindrical surface 25.

[0093] . In one embodiment, the first seat wall 19 is configured to be fitted onto the respective first coupling portion 22 of one of the respective first cylinder supports 9, 9', so that the cam 6 is freely rotatable about the first axis X1 , allowing a user to orient the cam 6 with the second positioning seat 14 along the circular trajectory of the second cylinder 4 and / or of the respective second cylinder supports 10, 10' and, by rotating the respective oscillating lever 11 , 11', the cam 6 is tightened between the respective first cylinder support 9, 9' and a respective second cylinder support 10, 10', uniquely determining the printing format distance D between the first axis X1 and the second axis X2.

[0094] . In one embodiment, the cam 6 can be connected to the first coupling portion so as to be supported by the coupling portion, uniquely oriented with the second positioning seat 14 along the circular trajectory of the second cylinder 4 and / or of the respective second cylinder supports 10, 10', so that by rotating the respective oscillating lever 11 , 11', the cam 6 is automatically tightened between the respective first cylinder support 9, 9' and a respective second cylinder support 10, 10', uniquely determining the printing format distance D between the first axis X1 and the second axis X2. In one embodiment, the cam 6 can be connected to the first coupling portion so as to be supported by the coupling portion by means of a form-fit coupling between respective polygonal surfaces of the cam and the coupling portion.

[0095] . In one embodiment, the cam 6 comprises at least one positioning seat or orientation fixing seat 32 configured to receive a positioning pin connected and / or connectable to the respective first cylinder support 9, 9' and / or to the support structure 2, so that the cam 6 is uniquely supported and oriented by the respective first cylinder support 9, 9' and / or to the support structure 2. In one embodiment, the at least one orientation fixing seat 32 comprises a first hole or axial hole 33 at leastpartially formed along a direction parallel to the first axis X1 when the cam 6 is connected to the printing unit. In one embodiment, the first hole 33 is formed by removing material from a face of the cam body transverse to the thickness of the cam 6. In one embodiment, the at least one orientation fixing seat 32 comprises a second hole or radial hole 34 at least partially formed along a direction perpendicular to the direction of the first axis X1 . In one embodiment, the second hole 34 is formed by removing material from the thickness of the cam body 6. In one embodiment, the first hole and the second hole are in communication. In one embodiment, the first hole is at least partially delimited by a cylindrical wall portion. In one embodiment, the second hole is at least partially delimited by a cylindrical wall portion. In one embodiment, the first cylinder support or left-hand first cylinder support 9 comprises a first positioning pin or left-hand positioning pin. In one embodiment, the printing unit 1 comprises a second positioning pin or right-hand positioning pin. In one embodiment, the second positioning pin or right-hand positioning pin is connected to the support structure on the same side to which the first cylinder support or right-hand first cylinder support 9' is constrained. In one embodiment, the first cylinder support or right-hand first cylinder support 9' comprises the second positioning pin or right-hand positioning pin. In one embodiment, the second positioning pin or righthand positioning pin and the first positioning pin or left-hand positioning pin extend parallel to the first axis X1. In one embodiment, the second positioning pin or right-hand positioning pin and the first positioning pin or left-hand positioning pin are facing each other.

[0096] . In one embodiment, the at least one inking unit thrust device 31 is configured to adjust the distance between the inking axis X5 and the first axis X1 . For example, the at least one inking unit thrust device 31 comprises a hydraulic or pneumatic thrust device configured to push the inking cylinders, moving them towards the first axis X1 .

[0097] . In one embodiment, the cam 6 comprises a third positioning seat 18 configured to receive or abut with a respective third coupling portion 26. In one embodiment, the respective inking cylinder 16 comprises the respective third coupling portion 26, or the respective inking cylinder support 17 comprises the respective third coupling portion 26, so that when the cam 6 is tightened and interposed directly or indirectly between the first cylinder 3 and the second cylinder 4 under a constant pushing action from the inking unit thrust device 31 , and the third positioning seat 18 abuts the respective third coupling portions, the relative position between the first axis X1 and each inking axis X5 is uniquely determined.

[0098] . In one embodiment, the printing unit 1 avoids including positioning motors to move the first axis X1 , the second axis X2, and the inking axis X3.

[0099] . In one embodiment, the third positioning seat 18 comprises a third seat wall 30 that is at least partially cylindrical and coaxial to the first axis X1 , configured to abut with each respective third coupling portion 26. In one embodiment, the third seat wall 30 is coaxial to the first seat wall 19,wherein the third seat wall 30 has a radius greater than the radius of the first seat wall relative to the first axis X1 .

[0100] . In one embodiment, each third coupling portion 26 comprises a third cylindrical surface 29 coaxial to the respective inking axis X5 configured to abut with the third positioning seat 18.

[0101] . In one embodiment, the third coupling portion 26 is the thickness that circumferentially delimits a positioning disc or a portion of a positioning disc connected to the respective inking cylinder 16 and / or the respective inking cylinder support 17. In one embodiment, the third coupling portion 26 is fixed with respect to the cam 6 and does not rotate relative to it.

[0102] . In one embodiment, the second coupling seat 18 is the thickness of the shaped body of the cam that circumferentially delimits a semi-circular crown portion of the cam 6.

[0103] . In one embodiment, at least one of the respective first cylinder supports 9, 9' is connected to the support frame 2 by means of a respective first cylinder locking lever 27. The respective first cylinder locking lever 27 is connected to the support frame 2 rotatably around a respective first cylinder locking axis X6 that is parallel to the first axis X1 , wherein the respective first cylinder locking lever 27 is connected to the support frame 2 translatably along the respective first cylinder locking axis, so as to translate at least one of the respective first cylinder supports 9, 9' away from the respective end of the first cylinder and so as to rotate at least one of the respective first cylinder supports 9, 9' to avoid interfering with the size of the first cylinder 3 to allow its replacement with a further first cylinder for a further printing format. The respective first cylinder locking lever 27 comprises locking means configured to lock the position of the first cylinder locking lever 27 along and around the respective first cylinder locking axis.

[0104] . In one embodiment, at least one of the respective second cylinder supports 10, 10' is connected to the respective oscillating lever 11 , 11 ' by means of a respective second cylinder locking lever 28. The respective second cylinder locking lever 28 is connected to the respective oscillating lever 11 , 11 ' rotatably around a respective second cylinder locking axis X7 that is parallel to the second axis X2 and to the respective oscillating axis X4, wherein the respective second cylinder locking lever 28 is connected to the respective oscillating lever 11 , 11 ' translatably along the respective second cylinder locking axis, so as to separate by translating at least one of the respective second cylinder supports 10, 10' away from the respective end of the second cylinder and so as to rotate at least one of the respective second cylinder supports 10, 10' to avoid interfering with the size of the second cylinder 4 to allow its replacement with a further second cylinder for the further printing format. The respective second cylinder locking lever 28 comprises locking means configured to lock the position of the respective second cylinder locking lever 28 along and / or around the second cylinder locking axis.

[0105] . In accordance with one embodiment, the cam 6 is made of a structural material, forexample, a metallic material, or a high-strength composite material.

[0106] . In one embodiment, the printing unit 1 can be reversibly connected to the variable format offset printing machine 100, forming a module that can be separated from the printing machine. In one embodiment, the support structure 2 of the printing unit 1 is made enbloc or as a separate piece from the support structure of the variable format offset printing machine 100.

[0107] . The present invention also relates to a variable format offset printing machine 100, comprising at least one printing unit 1 according to any of the embodiments previously described. In one embodiment, the printing unit 1 can be reversibly connected to the variable format offset printing machine 100, forming a module that can be separated from the printing machine. In one embodiment, the support structure 2 of the printing unit 1 is made as a separate piece from the support structure of the variable format offset printing machine 100, as shown in figures 12A and 12B.

[0108] . The present invention also relates to a cam 6 for a printing unit 1 .

[0109] . The cam 6 is configured to be used in a variable format offset printing unit 1. The printing unit 1 is, for example, a printing unit 1 according to any of the embodiments previously described.

[0110] . According to one aspect, the cam 6 comprises a shaped body configured to uniquely define or set the printing format distance D between the second axis X2 of the second cylinder 4 and the first axis X1 of the first cylinder 3, i.e., the minimum distance that can exist between the second axis X2 of the second cylinder 4 and the first axis X1 of the first cylinder 3 when the cam is mounted on the printing unit. This minimum distance is the distance that allows the correct abutment for printing between the first cylinder and the second cylinder.

[0111] . According to one aspect, the cam 6 is configured to be connected, for example with form-fit coupling, directly or indirectly between the first cylinder 3 and the second cylinder 4 and interposed directly or indirectly between the first cylinder 3 and the second cylinder 4. When the cam 6 is interposed between the first cylinder 3 and the second cylinder 4, it acts as a structural constraint that prevents the rotation of each oscillating lever 11 , 11 ' at least towards the first axis X1 , uniquely defining the printing format distance D between the second axis X2 and the first axis X1 , avoiding adjustment steps of the printing format distance D. The cam 6 avoids including adjustment means to adjust the printing format distance D between the first cylinder 3 and the second cylinder 4. Form-fit coupling or connection means a mechanical connection between two or more elements based on their complementary geometry, such that the shape of one part fits, with or without clearance, the shape of the other, constraining their relative movement in one or more directions. For example, the surfaces of the parts that engage with form-fit coupling must have shapes that interlock or fit together. One example is the form-fit coupling between the first positioning seat of the cam made as a through hole and the respective first coupling portion 22 of one of the respective first cylinder supports 9, 9',wherein the geometries of the two parts are counter-shaped to fit the cam onto the first cylinder support. A further example is the form-fit coupling between the second positioning seat of the cam and the second coupling portion 23 of one of the respective second cylinder supports 10, 10', wherein the second positioning seat of the cam is a concave portion with a crescent, semi-circular, or semi- cylindrical profile that receives in abutment the second coupling portion 23, which is a convex portion that can abut, coupling with the concave portion.

[0112] . According to one aspect, the shaped body of the cam comprises a first positioning seat13, wherein the first positioning seat 13 is configured to be connected and constrained to a stationary portion of the first cylinder 3 or to one of the first cylinder supports 9, 9', and a second positioning seat14, wherein the second positioning seat 14 is configured to form an abutment for a stationary portion of the second cylinder 4 or for one of the second cylinder supports 10, 10'. In this way, when the first positioning seat 13 is connected and constrained directly or indirectly to the first cylinder 3, the cam 6 projects in an overhanging manner along a direction perpendicular to the first axis X1 with the second positioning seat 14 oriented to intercept the circular trajectory along which the second axis X2 is mobile when the second cylinder 4 is supported by each oscillating lever 11 , 11 ', to form a structural constraint that intercepts, directly or indirectly, the second cylinder 4 or one of its second cylinder supports 10, 10' during the rotation of each oscillating lever 11 , 11' towards the first axis X1 from the respective first angular position and against which the second cylinder 4 or one of its second cylinder supports 10, 10' abuts directly or indirectly, stopping and / or locking each oscillating lever 11 , 11 ' in at least one second angular position and uniquely setting the printing format distance D between the second axis X2 of the second cylinder 4 and the first axis X1 of the first cylinder 3.

[0113] . In one embodiment, the first positioning seat 13 has a first seat axis that is coaxial with the first axis X1. In one embodiment, the second positioning seat 14 has a second seat axis that is parallel to the second seat axis. In one embodiment, the first positioning seat 13 delimits a through hole coaxial with the first axis X1 , which is shaped to engage by form-fit or to be fitted onto the stationary portion of the first cylinder 3 or onto said one of the first cylinder supports 9, 9'.

[0114] . In one embodiment, the second positioning seat 14 is an open concave seat comprising an open cylindrical surface that develops around the second seat axis and subtends a central angle with respect to the second seat axis between 20° and 180°, so as to form said abutment for the stationary portion of the second cylinder 4 or for said one of the second cylinder supports 10, 10' during the rotation of the oscillating levers 11 , 11 ' towards the first axis X1 , and so as not to hinder the distancing of the second cylinder 4 and the second cylinder support 10, 10' during the rotation of the oscillating levers 11 , 11 ' towards the first angular position.

[0115] . In one embodiment, the cam 6 comprises an elongated central cam portion that connects the first positioning seat 13 and the second positioning seat 14, in a unique manner. In oneembodiment, the elongated central cam portion avoids including adjustment means for adjusting the distance between the first positioning seat 13 and the second positioning seat 14.

[0116] . In one embodiment, at least one cam 6 is a monolithic element configured to provide stability and precision in the abutment of the first cylinder 3 and the second cylinder 4.

[0117] . In one embodiment, the at least one cam 6 is also configured to be interposed directly between the first cylinder 3 and each inking cylinder 16, without interfering with the rotation of the first cylinder 3 and of each inking cylinder 16, or between a respective first cylinder support 9, 9' and each respective inking cylinder support 17, so as to form a structural constraint that uniquely defines a relative position between the first axis X1 and each inking axis X5, forming an abutment for each inking cylinder 16 or for each inking cylinder support 17.

[0118] . In one embodiment, the cam 6 is a monolithic element, undeformable under the working pressures of the actuating means of the inking cylinders and under the working pressures of the oscillating levers, configured to provide stability and precision both in the abutment of the first cylinder 3 and the second cylinder 4, and in the abutment of the inking cylinders 16 to the first cylinder 3. In one embodiment, at least one cam 6 is a monolithic element, undeformable under the working pressures of the oscillating levers, configured to provide stability and precision in the abutment of the first cylinder 3 and the second cylinder 4.

[0119] . In one embodiment, the cam 6 comprises an elastic locking device 35, wherein the elastic locking device 35 is housed in the orientation fixing seat 32, wherein the elastic locking device 35 is configured to elastically retain the positioning pin 13 in the orientation fixing seat 32 so as to elastically and reversibly lock the axial position of the cam 6 along the direction parallel to the first axis X1 . In one embodiment, the elastic locking device 35 is housed in the radial hole 32, and wherein the elastic locking device 35 is configured to elastically retain the positioning pin 13 in the axial hole 33. In one embodiment, the positioning pin 13 has a groove 37, forming a recess in the positioning pin 13. In one embodiment, the elastic locking device 35 comprises an interference element 38, such as a ball, movable along the direction along which the radial hole 32 is made between a retracted position and a maximum interference position, wherein the interference element 38 is constantly urged into the maximum interference position by an elastic element 39, such as a spring. In one embodiment, during the insertion of the positioning pin 13 into the axial hole 33, the positioning pin 13 interferes with the interference element 38 pushing it into the retracted position against the action of the elastic element 39, until the interference element 38 is inserted into the groove 37 of the positioning pin 13 urged towards the maximum interference position under the action of the elastic element 39, so as to elastically and reversibly lock the axial position of the cam 6 along the direction parallel to the first axis X1.

[0120] . The present invention also relates to a cam kit for a variable format offset printing unit.The cam kit comprises a first cam or first format cam according to any of the embodiments previously described, and at least a second cam or second format cam according to any of the embodiments previously described.

[0121] . The first cylinder 3, 3' and the second cylinder 4, 4' are selected, based on the printing format to be used in the printing unit 1 , from a first format first cylinder 3 and a first format second cylinder 4, or from a second format first cylinder 3' and a second format second cylinder 4'.

[0122] . The first format first cylinder 3 and the first format second cylinder 4 have a first format diameter and define a first printing format, and the printing format distance D between the first axis X1 of the first format first cylinder 3 and the second axis X2 of the first format second cylinder 4 is a first printing format distance D1 .

[0123] . The second format first cylinder 3' and the second format second cylinder 4' have a second format diameter and define a second printing format, and the printing format distance D between the first axis X1 of the second format first cylinder 3' and the second axis X2 of the second format second cylinder 4' is a second printing format distance D2, wherein the first format diameter is greater or smaller than the second format diameter.

[0124] . Each first format cam is configured to be used with the first format first cylinder 3 and the first format second cylinder 4, and each second format cam is configured to be used with the second format first cylinder 3' and the second format second cylinder 4'.

[0125] . The shaped body of the first cam is shaped to set the first printing format distance D1 between the first axis X1 and the second axis X2 when the first cam is mounted on the printing unit 1 together with the first format first cylinder 3 and the first format second cylinder 4, wherein the shaped body of the first cam is suitable to be interposed between the first format first cylinder 3 and the first format second cylinder 4, or between one of the first cylinder supports 9, 9' and one of the second cylinder supports 10, 10'.

[0126] . The shaped body of the second cam is shaped to set the second printing format distance D2 between the first axis X1 and the second axis X2 when the second cam is mounted on the printing unit 1 together with the second format first cylinder 3' and the second format second cylinder 4', wherein the shaped body of the second cam is suitable to be interposed between the second format first cylinder 3' and the second format second cylinder 4', or between one of the first cylinder supports 9, 9' and one of the second cylinder supports 10, 10'.

[0127] . The second printing format distance D2 is greater or smaller than the first printing format distance D1.

[0128] . The second format diameter is greater or smaller than the first format diameter. In one embodiment, the at least one cam 6 is made according to one or more of the embodiments previously described of the printing unit 1 .

[0129] . According to one aspect, the present invention also relates to a method for uniquely defining a printing format distance D for a printing unit 1 for a variable-format offset printing machine 100. The method comprises the steps of: - providing at least one cam or shaped element 6 configured to be interposed directly or indirectly between the first cylinder 3 and the second cylinder 4 so as to form a structural constraint that prevents the rotation of each oscillating lever 11 , 11' at least towards the first axis X1 , uniquely defining the printing format distance D between the second axis X2 of the second cylinder 4 and the first axis X1 of the first cylinder 3; - tightening the at least one cam 6 between the first cylinder 3 and the second cylinder 4 by pushing the second cylinder 4 towards the first cylinder 3, uniquely defining the printing format distance D between the second axis X2 and the first axis X1 , avoiding interference with the rotation of the first cylinder 3 and the second cylinder 4 respectively around the first axis X1 and the second axis X2, and avoiding adjustment steps of the printing format distance D.

[0130] . In one operational mode, the tightening step involves constantly pushing the second cylinder 4 towards the first cylinder 3 during the use of the printing unit, pressing the cam 6 directly or indirectly between the first cylinder and the second cylinder. In one operational mode, the cam 6 is a cam according to any of the previously described embodiments. In one operational mode, the printing unit is a printing unit according to any of the previously described embodiments.

[0131] . According to one aspect, the present invention relates to a method for uniquely defining a printing format distance D for a printing unit 1 of a variable-format offset printing machine 100. The printing unit 1 comprises a support structure 2; - a first cylinder 3, wherein the first cylinder 3 is rotatably supported by the support structure 2 around a first axis X1 , wherein the first cylinder 3 is supported at its opposite ends by respective first cylinder supports 9, 9', and wherein the first cylinder 3 is a plate cylinder; - a second cylinder 4, wherein the second cylinder 4 is rotatably supported around a second axis X2, wherein the second axis X2 is parallel to the first axis X1 , wherein the second cylinder 4 is supported at its opposite ends by respective oscillating levers 11 , 11 ' by means of respective second cylinder supports 10, 10', wherein the second cylinder 4 is a transfer cylinder; wherein each oscillating lever 11 , 11 ' is pivoted to the support structure 2 in rotation around an oscillation axis X4 so that the second axis X2 is movable along a circular trajectory centered on the oscillation axis X4 to be positioned at the printing format distance D from the first axis X1 , wherein the oscillation axis X4 is parallel to the second axis X2. The printing unit 1 further comprises: - a third cylinder 5, wherein the third cylinder 5 which is rotatably supported by the support structure 2 around a third axis X3, wherein the third axis X3 is parallel to the first axis X1 and to the second axis X2, wherein the third cylinder 5 is supported at its axial ends by respective eccentric or linear supports 21 , 21 , wherein the third cylinder 5 is a counter-pressure cylinder.

[0132] . The method comprises the step of providing at least one cam or shaped element 6,wherein the cam 6 is configured to be interposed, for example by form-fit coupling, directly or indirectly between the first cylinder 3 and the second cylinder 4 so as to form a structural constraint that prevents the rotation of each oscillating lever 11 , 11 ' at least towards the first axis X1 , uniquely defining the printing format distance D between the second axis X2 of the second cylinder 4 and the first axis X1 of the first cylinder 3, wherein the method comprises the step of tightening the at least one cam 6 between the first cylinder 3 and the second cylinder 4 by pushing the second cylinder 4 towards the first cylinder 3, uniquely defining the printing format distance D between the second axis X2 and the first axis X1 , avoiding interference with the rotation of the first cylinder 3 and the second cylinder 4 respectively around the first axis X1 and the second axis X2, and avoiding adjustment steps of the printing format distance D. In other words, it is the cam 6 that uniquely establishes the printing format distance between the first cylinder and the second cylinder, and it is sufficient to operate the oscillating levers from the first angular position towards the second angular position to set the correct printing format distance, which is established when the second cylinder or its supports abut against the cam, tightening it.

[0133] . In one operational mode, the printing unit 1 is of a variable-format offset printing machine 100, in which each oscillating lever 11 , 11 ' is pivoted to the support structure 2 in rotation around said oscillation axis X4 at least between a first angular position and a second angular position, and vice versa, in which each oscillating lever 11 , 11 ' is configured to support the second cylinder 4 at least between the first angular position and the second angular position by rotating towards the first axis X1 and moving the second axis X2 along said circular trajectory, wherein the method comprises the steps of: - connecting the cam 6, directly or indirectly, to the first cylinder 3; and - orienting the cam 6 by placing it along the circular trajectory along which the second axis X2 is movable. The tightening step involves rotating each oscillating lever 11 , 11 ' supporting the second cylinder 4 from the first angular position towards the second angular position, moving the second axis X2 along the circular trajectory towards the first axis X1 until the cam 6 is tightened and interposed between the first cylinder 3 and the second cylinder 4, forming a structural constraint that prevents the rotation of each oscillating lever 11 , 11' towards the first axis X1 , uniquely defining the printing format distance D between the second axis X2 of the second cylinder 4 and the first axis X1 of the first cylinder 3. The method for uniquely defining a printing format distance D is a method for setting the printing format distance.

[0134] . According to one aspect, the present invention relates to a method for setting a printing format distance D in a variable-format offset printing unit 1 for a variable-format offset printing machine 100. In one operational mode, the method for setting a printing format distance D is a method for uniquely defining a printing format distance D, thanks to the positioning of a cam and the movement of the oscillating levers until the cam is tightened.

[0135] . The printing unit 1 comprises a support structure 2. The printing unit 1 comprises a pair of first cylinder supports 9, 9', wherein the first cylinder supports 9, 9' are connected to the support structure 2; a first cylinder 3, 3', wherein the first cylinder 3, 3' is supported at its opposite ends in rotation around a first axis X1 by the first cylinder supports 9, 9', wherein the first cylinder 3, 3' is a plate cylinder. The printing unit 1 comprises a pair of second cylinder supports 10, 10'; a second cylinder 4, 4', wherein the second cylinder 4, 4' is supported at its opposite ends in rotation around a second axis X2 by the second cylinder supports 10, 10', wherein the second axis X2 is parallel to the first axis X1 , wherein the second cylinder 4, 4' is a transfer cylinder. The printing unit 1 comprises a pair of oscillating levers 11 , 11', wherein the oscillating levers 11 , 11' each support a second cylinder support 10, 10' of the pair of first cylinder supports 10, 10'. Each oscillating lever 11 , 11 ' is pivoted to the support structure 2 in rotation around an oscillation axis X4 between a first angular position or format change angular position and at least a second angular position or printing format angular position, and vice versa, so that when the second cylinder 4, 4' is supported by the pair of second cylinder supports 10, 10', the second axis X2 is movable along a circular trajectory centered on the oscillation axis X4 to bring closer together or further apart the second cylinder 4, 4' to the first cylinder 3, 3', bringing them together to transfer ink or distancing them, for example to prevent ink transfer or to allow replacement of the first cylinder 3, 3' and the second cylinder 4, 4', wherein the oscillation axis X4 is parallel to the second axis X2.

[0136] . When each oscillating lever 11 , 11 ' is in the second angular position, the second axis X2 is positioned at the printing format distance D from the first axis X1 .

[0137] . When each oscillating lever 11 , 11 ' is in the first angular position, the first cylinder 3, 3' and the second cylinder 4, 4' are distanced so that the second cylinder 4, 4' and the first cylinder 3, 3' can be separated from the respective first cylinder supports 10, 10' and the respective second cylinder supports 11 , 11' and replaced to change the printing format.

[0138] . The printing unit 1 comprises a third cylinder 5, wherein the third cylinder 5 is rotatably supported by the support structure 2 around a third axis X3, wherein the third axis X3 is parallel to the first axis X1 and the second axis X2, wherein the third cylinder 5 is supported at its axial ends by respective eccentric or linear supports 21 , 21 , wherein the third cylinder 5 is a counter-pressure cylinder.

[0139] . The method comprises the step of: a -providing at least one cam 6, 6’.

[0140] . The at least one cam 6 is configured to be interposed, for example with form-fit coupling, directly or indirectly, between the first cylinder 3, 3' and the second cylinder 4, 4', so as to form a structural constraint that prevents the rotation of each oscillating lever 11 , 11 ' towards the first axis X1 when each oscillating lever 11 , 11 ' is in the second angular position, uniquely defining the printing format distance D between the second axis X2 of the second cylinder 4, 4' and the first axisX1 of the first cylinder 3, 3'. The at least one cam 6 thus forms a mechanical element that limits the rotation of the oscillating levers towards the first axis X1 to the second angular position, since once this second angular position has been reached, the cam remains tightened and the first axis X1 and the second axis X2 remain at the printing format distance D, indirectly imposed by the cam.

[0141] . When each oscillating lever 11 , 11 ' is in the first angular position, the method comprises the step of b- connecting the at least one cam 6, directly or indirectly, to the first cylinder 3, 3', and the step of c- orienting the at least one cam 6 by positioning it along the circular trajectory along which the second axis X2 is movable.

[0142] . After the at least one cam 6 has been connected and oriented according to the previous steps b and c, the method comprises the step of d- rotating each oscillating lever 11 , 11 ' supporting the second cylinder 4, 4' from the first angular position towards at least one second angular position, moving the second axis X2 along the circular trajectory towards the first axis X1 , until the cam 6 is tightened and interposed between the first cylinder 3, 3' and the second cylinder 4, 4'.

[0143] . When the at least one cam 6 is tightened and interposed between the first cylinder 3, 3' and the second cylinder 4, 4', the at least one cam 6 forms said structural constraint that prevents the rotation of each oscillating lever 11 , 11 ' towards the first axis X1 , stopping and / or locking each oscillating lever 11 , 11 ' in the at least one second angular position and uniquely defining the printing format distance D between the second axis X2 of the second cylinder 4, 4' and the first axis X1 of the first cylinder 3, 3'.

[0144] . In offset printing, when the second axis X2 is positioned at the printing format distance D from the first axis X1 , the first cylinder and the second cylinder are correctly brought together, and it is possible to transfer the ink from the first cylinder 3, 3' to the second cylinder 4, 4' and then print the material to be printed, either a sheet or a web, between the second cylinder 4, 4' and the third cylinder 5.

[0145] . Thanks to the described method, it is possible, with a single rotational movement of the oscillating levers, to bring the second cylinder towards the first cylinder until tightening the cam 6 under pressure, directly between stationary portions of the first cylinder and the second cylinder, or indirectly between the first cylinder supports and the second cylinder supports. In a simple and quick manner, once the cam is mounted directly or indirectly on the first cylinder and has been oriented to intercept the circular trajectory of the second axis, and once the cam is tightened, the printing format distance is set, with the sole rotation of the oscillating levers towards the first axis X1 , without having to precisely control, for example by means of a control unit, the position of the levers. The correct position of the oscillating levers for the printing format predetermined by the first cylinder and the second cylinder is determined mechanically by the presence of the cam, which locks the oscillating levers once the cam is tightened between the first cylinder and the second cylinder, or between a firstcylinder support and a second cylinder support, thus determining, by means of a physical and structural constraint, namely the cam, the printing format distance between the first axis and the second axis.

[0146] . In one operational mode, the step b comprises connecting the cam 6, directly or indirectly, to the first cylinder 3 with the first positioning seat 13. Furthermore, the step c comprises orienting the cam 6 by positioning the second positioning seat 14 along the circular trajectory along which the second axis X2 is movable. The steps b and c may occur in succession or simultaneously.

[0147] . Furthermore, the step d may comprise rotating each oscillating lever 11 , 11' supporting the second cylinder 4 from the first angular position towards the second angular position, moving the second axis X2 along the circular trajectory towards the first axis X1 , until the second cylinder 4 comes into abutment, directly or indirectly, against the second positioning seat 14, and until the cam or shaped element 6 is tightened and interposed between the first cylinder 3 and the second cylinder 4, forming a structural constraint that prevents the rotation of each oscillating lever 11 , 11 ' towards the first axis X1 , uniquely defining the printing format distance D.

[0148] . In one operational mode, the step d may comprise rotating each oscillating lever 11 , 11 ' supporting the second cylinder 4 from the first angular position towards the second angular position, moving the second axis X2 along the circular trajectory towards the first axis X1 , until the at least one cam 6 is tightened in abutment between the first coupling portion 22 and the second coupling portion 23 accommodated respectively in the first positioning seat 13 and the second positioning seat 14, forming a structural constraint that prevents the rotation of each oscillating lever 11 , 11 ' towards the first axis X1 , uniquely defining the printing format distance D.

[0149] . In one operational mode, the step c of orienting the cam 6 is automatically defined. In one operational mode, the step c of orienting the cam 6 is automatically defined by the coupling between the cam 6 and a respective first cylinder support. In one operational mode, the orienting step of the cam 6 is automatically defined by the coupling between the first positioning seat 13 and the first coupling portion 22, whereby once the cam 6 is connected to the first coupling portion 22, the first coupling portion 22 uniquely supports the cam 6 with the second positioning seat 14 oriented along said circular trajectory. In one operational mode, the step c of orienting the cam 6 is automatically defined by the coupling between the first positioning seat 13 and the first coupling portion 22, and by the coupling between the orientation fixing seat 32 of the cam 6 and a respective positioning pin 36, 36' constrained to the first cylinder support 9, 9' or to the support structure 2.

[0150] . In one operational mode, the step d comprises constantly pushing the second cylinder 4 towards the first cylinder 3 during the printing of the printing unit 1 , pressing the cam 6 directly or indirectly between the first cylinder 3 and the second cylinder 4, so as to constantly maintain the printing format distance D.

[0151] . Thanks to the cam 6 of the present invention, it is possible to avoid step-by-step control of the position of the inking cylinders with respect to the first cylinder, as it is possible to control the position of the inking cylinders between a first retracted position, in which the inking cylinders are in a rest position under the action of the thrust actuators, and an abutment position, in which the inking cylinders, in particular a stationary portion thereof or a respective inking cylinder support, are directly or indirectly in abutment against the cam, defining the relative position between the first axis X1 and each inking axis X5, correct for the printing format defined by the pair of the first cylinder and the second cylinder having equal diameter.

[0152] . In one operational mode, the method comprises the step e- of setting the relative position between the first axis X1 and each inking axis X5.

[0153] . In one operational mode, the step e comprises moving each inking cylinder 16 towards the first cylinder 3 until each inking cylinder 16 or each inking cylinder support 17 comes into abutment against the cam 6 and the at least one cam 6 is interposed between the first cylinder 3 and each inking cylinder 16, thus uniquely defining the relative position between the first axis X1 and each inking axis X5.

[0154] . In one operational mode, the step e comprises constantly pushing each inking cylinder 16 towards the first cylinder 3 during the printing of the printing unit 1 , pressing, preferably under a hydraulic or pneumatic pushing action, the cam 6 directly or indirectly between the first cylinder 3 and each inking cylinder 16, so as to constantly maintain the relative position between the first axis X1 and each inking axis X5.

[0155] . In one operational mode, the step e comprises moving each inking cylinder 16 towards the first cylinder 3 until each respective third coupling portion 26 comes into abutment against the third positioning seat 18 of the cam 6 and the at least one cam 6 is interposed between the first cylinder 3 and each inking cylinder 16, thus uniquely defining the relative position between the first axis X1 and each inking axis X5. In one operational mode, the step e may occur before or after the step d, and takes place before or after the at least one cam 6 is tightened between the first cylinder 3 and the second cylinder 4.

[0156] . In one embodiment or in one operational mode, the first cylinder 3, 3' and the second cylinder 4, 4' are selected, according to the printing format to be used in the printing unit 1 , from a first cylinder of first format 3 and a second cylinder of first format 4, or a first cylinder of second format 3' and a second cylinder of second format 4'. In one embodiment or in one operational mode, the at least one cam 6 is selected, according to the printing format to be used in the printing unit 1 , from a cam of first format and a cam of second format, wherein each cam of first format is configured to be used with the first cylinder of first format and the second cylinder of first format, and each cam of second format is configured to be used with the first cylinder of second format and the second cylinderof second format.

[0157] . In one operational mode, the method comprises the step f- of varying the printing format from the first printing format to the second printing format, or vice versa.

[0158] . In the case of varying the printing format from the first printing format to the second printing format, the step f comprises rotating each oscillating lever 11 , 11 ' towards the first angular position, and when each oscillating lever 11 , 11' is in the first angular position, separating the first format first cylinder 3 and the first format second cylinder 4 from the first cylinder supports 9, 9' and from the second cylinder supports 10, 10' and / or from the support structure 2, separating each cam of first format from the support structure 2 and / or from the first cylinder supports 9, 9', connecting and orienting each cam of second format to the support structure 2 and / or to the first cylinder supports 9, 9' by repeating steps b and c, connecting the second format first cylinder 3' and the second format second cylinder 4' to the first cylinder supports 9, 9' and to the second cylinder supports 10, 10' and / or from the support structure 2. After the step f, the method comprises repeating step d by rotating each oscillating lever 11 , 11' towards the second angular position, tightening each second format cam or each first cam format directly or indirectly between the first cylinder 3, 3' and the second cylinder 4, 4', defining the second printing format distance D2 between the first axis X1 of the first cylinder of second format 3' and the second axis X2 of the second cylinder of second format 4'.

[0159] . In the case of varying the printing format from the second printing format to the first printing format, the step f comprises rotating each oscillating lever 11 , 11 ' towards the first angular position, and when each oscillating lever 11 , 11 ' is in the first angular position, separating the second format first cylinder 3' and the second format second cylinder 4' from the first cylinder supports 9, 9' and from the second cylinder supports 10, 10' and / or from the support structure 2, separating each second format cam from the support structure 2 and / or from the first cylinder supports 9, 9', connecting and orienting each first format cam to the support structure 2 and / or to the first cylinder supports 9, 9' by repeating steps b and c, connecting the first format first cylinder 3 and the first format second cylinder 4 to the first cylinder supports 9, 9' and to the second cylinder supports 10, 10' and / or to the support structure 2, wherein the method after the step f , the method comprises repeating step d by rotating each oscillating lever 11 , 11' towards the second angular position, tightening each first format cam directly or indirectly between the first cylinder 3, 3' and the second cylinder 4, 4', defining the first printing format distance D1 between the first axis X1 of the first format first cylinder 3 and the second axis X2 of the first format second cylinder 4.

[0160] . In one operational mode, after completing a printing cycle or in the event of a machine stop, for example to clean the machine or for a machine inspection or check, the method comprises a disengagement step, in which, during the disengagement step, each oscillating lever 11 , 11' is rotated towards a third angular position or disengagement angular position and in which the second cylinder 4is moved away from each cam 6 and is supported by each oscillating lever 11 , 11' in the third angular position without directly or indirectly contacting each cam 6, wherein the third angular position is between the first angular position and the second angular position. In one operational mode or in one embodiment, the third angular position of the oscillating levers is rotated by an angle of rotation between 1 and 5 degrees with respect to the second angular position of the oscillating levers. In one operational mode or in one embodiment, the second angular position of the oscillating levers is rotated by an angle between 3 and 40 degrees with respect to the first angular position of the oscillating levers. In one operational mode or in one embodiment, the second angular position of the oscillating levers is rotated by an angle between 20 and 40 degrees, preferably 30 degrees, with respect to the first angular position of the oscillating levers, when the cam of first format and the pair of first cylinder and second cylinder for the first printing format are employed. In one operational mode or in one embodiment, the second angular position of the oscillating levers is rotated by an angle between 2 and 5 degrees, preferably 3 degrees, with respect to the first angular position of the oscillating levers, when the cam of second format and the pair of first cylinder and second cylinder for the second printing format are employed. In one operational mode or in one embodiment, the second printing format is the maximum acceptable printing format for the printing unit 1. In one operational mode or in one embodiment, the first printing format is the minimum acceptable printing format for the printing unit 1 .

[0161] . In one operational mode, following the disengagement step, to start a new printing cycle, the method provides for rotating each oscillating lever 11 , 11' supporting the second cylinder 4 from the third angular position towards at least one second angular position, moving the second axis X2 along the circular trajectory towards the first axis X1 , until the cam 6 is tightened and interposed between the first cylinder 3 and the second cylinder 4, similarly to step d, but starting from the third angular position instead of from the first angular position.

[0162] . Thanks to the proposed solutions, the at least one cam forms a monolithic undeformable element configured to provide stability and precision in the bringing together of the first cylinder and the second cylinder.

[0163] . Thanks to the proposed solutions, the at least one cam forms a monolithic undeformable element configured to provide stability and precision in the bringing together of the inking cylinders and the first cylinder.Thanks to the proposed solutions, the at least one cam offers long-term stability of the position of the cylinders with which it is in direct or indirect contact, not being subject to dimensional variation.REFERENCE LISTprinting unit support structure first cylinder or plate cylinder second cylinder or intermediate cylinder or transfer cylinder third cylinder or impression cylinder cam or shaped element first cylinder support or left-side first cylinder support ’ first cylinder support or right-side first cylinder support 0 second cylinder support or left-side second cylinder support 0’ second cylinder support or right-side second cylinder support 1 oscillating lever or first oscillating lever or left-side oscillating lever1’ oscillating lever or second oscillating lever or right-side oscillating lever 2 lever thrust device or second cylinder thrust device 3 first positioning seat 4 second positioning seat 5 inking unit 6 inking cylinder 7 inking cylinder support 8 third positioning seat 9 wall of first seat 0 wall of second seat 1 third cylinder support 1’ third cylinder support 2 first coupling portion 3 second coupling portion 4 first cylindrical surface or cylindrical surface of first coupling portion5 second cylindrical surface or cylindrical surface of second coupling portion6 third coupling portion 7 first cylinder locking lever 8 second cylinder locking lever 9 third cylindrical surface or cylindrical surface of third coupling portion0 third seat wall 1 inking unit thrust device 2 orientation fixing seat or positioning seat 3 lever connection rod or lever synchronization rod34 elongated central portion of cam35 elastic retaining device36 right-side positioning pin36’ left-side positioning pin 37 groove38 interference element or sphere39 elastic elementX1 first axis or axis of first cylinder X2 second axis or axis of second cylinderX3 third axis or axis of third cylinderX4 oscillation axisX5 inking axisX6 axis of first cylinder locking lever X7 axis of second cylinder locking lever

Claims

CLAIMS1. A method for setting a print format distance (D) in a variable format offset type printing unit (1 ) for a variable print format offset printing machine (100), wherein the printing unit (1 ) comprises- a support structure (2);- a pair of first cylinder supports (9, 9’), wherein the first cylinder supports (9, 9’) are connected to the support structure (2),- a first cylinder (3, 3’), wherein the first cylinder (3, 3’) is supported at its opposite ends in rotation about a first axis (X1) by the first cylinder supports (9, 9’), wherein the first cylinder (3, 3’) is a plate cylinder;- a pair of second cylinder supports (10, 10’),- a second cylinder (4, 4’), wherein the second cylinder (4, 4’) is supported at its opposite ends in rotation about a second axis (X2) by the second cylinder supports (10, 10’), wherein the second axis (X2) is parallel to the first axis (X1), wherein the second cylinder (4, 4’) is a transfer cylinder,- a pair of oscillating levers (11 , 11’), wherein the oscillating levers (11 , 11’) each support a second cylinder support (10, 10’) of the pair of second cylinder supports (10, 10’), wherein each oscillating lever (11 , 11’) is pivoted to the support structure (2) in rotation about an oscillation axis (X4) between a first angular position or format change angular position and at least one second angular position or print format angular position, and vice versa, such that when the second cylinder (4, 4’) is supported by the pair of second cylinder supports (10, 10’) the second axis (X2) is movable along a circular trajectory centred on the oscillation axis (X4), wherein the oscillation axis (X4) is parallel to the second axis (X2), wherein, when each oscillating lever (11 , 11’) is in the second angular position, the second axis (X2) is positioned at the print format distance (D) from the first axis (X1), wherein when each oscillating lever (11, 11’) is in the first angular position, the first cylinder (3, 3’) and the second cylinder (4, 4’) are spaced such that the second cylinder (4, 4’) and the first cylinder (3, 3’) can be removed from their respective first cylinder supports (10, 10’) and from their respective second cylinder supports (11, 11’) and replaced to vary the print format;-a third cylinder (5), wherein the third cylinder (5) is supported in rotation by the support structure (2) about a third axis (X3), wherein the third axis (X3) is parallel to the first axis (X1 ) and to the second axis (X2), wherein the third cylinder (5) is supported at its axial ends by respective eccentric or linear supports (21 , 21 ), wherein the third cylinder (5) is an impression cylinder, wherein the method comprises the steps of:a - providing at least one cam (6, 6’), wherein the at least one cam (6) is configured to be interposed, directly or indirectly, between the first cylinder (3, 3’) and the second cylinder (4, 4’); wherein, when each oscillating lever (11, 11’) is in the first angular position, the method comprises the steps of: b- connecting the at least one cam (6), directly or indirectly, to the first cylinder (3, 3’), and c- orienting the at least one cam (6) by positioning it along the circular trajectory along which the second axis (X2) is movable, wherein, once the at least one cam (6) has been connected and oriented, the method comprises the step of: d- actuating in rotation each oscillating lever (11 , 11’) supporting the second cylinder (4, 4’), from the first angular position towards the at least one second angular position, moving the second axis (X2) along the circular trajectory towards the first axis (X1 ), until the cam (6) is clamped and interposed between the first cylinder (3, 3’) and the second cylinder (4, 4’), wherein when the at least one cam (6) is clamped and interposed between the first cylinder (3, 3’) and the second cylinder (4, 4’), the at least one cam (6) forms a structural constraint that prevents rotation of each oscillating lever (11, 11’) towards the first axis (X1), stopping or locking each oscillating lever (11, 11’) in the at least one second angular position and uniquely defining the print format distance (D) between the second axis (X2) of the second cylinder (4, 4’) and the first axis (X1) of the first cylinder (3, 3’).

2. The method according to the preceding claim, wherein the cam (6) comprises:-a first positioning seat (13), wherein the first positioning seat (13) is configured to be connected, directly or indirectly, to the first cylinder (3) without interfering with the rotation of the first cylinder (3), and-a second positioning seat (14), wherein the second positioning seat (14) is configured to be connected, directly or indirectly, to the second cylinder (4) without interfering with the rotation of the second cylinder (4), wherein step b) provides for connecting the cam (6), directly or indirectly, to the first cylinder (3) with the first positioning seat (13), wherein step c) provides for orienting the cam (6) by placing the second positioning seat (14) along the circular trajectory along which the second axis (X2) is movable, wherein step d) provides for actuating in rotation each oscillating lever (11, 1 T) supporting the second cylinder (4), from the first angular position towards the second angular position, moving the second axis (X2) along the circular trajectory towards the first axis (X1), until the second cylinder (4) abuts, directly or indirectly, against the second positioning seat (14), anduntil the cam (6) is clamped and interposed between the first cylinder (3) and the second cylinder (4), forming said structural constraint that prevents rotation of each oscillating lever (11 , 11’) towards the first axis (X1), uniquely defining the print format distance (D).

3. Method according to the preceding claim, wherein the first positioning seat (13) is shaped to accommodate a respective first coupling portion (22), wherein the first cylinder (3) comprises the respective first coupling portion (22) at a stationary end portion of the first cylinder, so that the cam (6) can be directly interposed against the first cylinder (3), or each of the respective first cylinder supports (9, 9’) comprises the respective first coupling portion (22), wherein the respective first cylinder supports (9, 9’) are configured to rotatably support respective ends of the first cylinder (9), so that the cam (6) can be indirectly interposed against the first cylinder (3) and without interfering with the rotation of the first cylinder (9), wherein the second positioning seat (14) is shaped to accommodate a respective second coupling portion (23), wherein the second cylinder (4) comprises the respective second coupling portion (23) at a stationary end portion of the second cylinder, so that the cam (6) can be directly interposed against the second cylinder (4), or each of the second cylinder supports (10, 10’), connected to the respective oscillating lever (11 , 11’), comprises the respective second coupling portion (23), wherein the second cylinder supports (10, 10’) are configured to rotatably support respective ends of the second cylinder (4), so that the cam (6) can be indirectly interposed against the second cylinder (4), wherein step d) provides for actuating in rotation each oscillating lever (11 , 11’) supporting the second cylinder (4), from the first angular position towards the second angular position, moving the second axis (X2) along the circular trajectory towards the first axis (X1), until the at least one cam (6) is clamped in abutment between the first coupling portion (22) and the second coupling portion (23) respectively accommodated in the first positioning seat (13) and in the second positioning seat (14), forming a structural constraint that prevents the rotation of each oscillating lever (11 , 11’) towards the first axis (X1), uniquely defining the print format distance (D).

4. Method according to claims 2 and 3, wherein during stap b), the cam (6) is connectable to the first coupling portion (22) so as to be supported by the first coupling portion (22), uniquely oriented with the second positioning seat (14) in cantilever arrangement along said circular trajectory so that by rotating the respective oscillating lever (11, 11’), the cam (6) is automatically clamped in abutment between the first coupling portion (22) andthe second coupling portion (23) respectively accommodated in the first positioning seat (13) and in the second positioning seat (14), uniquely determining the print format distance (D) between the first axis (X1) and the second axis (X2), wherein step c) of orienting the cam (6) is automatically defined by the coupling between the first positioning seat (13) and the first coupling portion (22), wherein once the cam (6) is connected to the first coupling portion (22), the first coupling portion (22) supports the cam (6) in a unique manner with the second positioning seat (14) oriented along said circular trajectory.

5. Method according to any preceding claim, wherein step d) provides for constantly pushing the second cylinder (4) towards the first cylinder (3) during printing by the printing unit (1), pressing the cam (6) directly or indirectly between the first cylinder (3) and the second cylinder (4).

6. Method according to any preceding claim, wherein the printing unit (1 ) comprises an inking unit (15), wherein the inking unit (15) comprises at least one inking cylinder (16) supported in rotation about a respective inking cylinder axis (X5) by respective inking cylinder supports (17), wherein each inking axis (X5) is parallel to the first axis (X1), wherein the inking unit (15) comprises thrust actuators configured to adjust the distance between the inking axis (X5) and the first axis (X1 ), wherein the at least one cam (6) is further configured to be interposed directly between the first cylinder (3) and each inking cylinder (16), without interfering with the rotation of the first cylinder (3) and each inking cylinder (16), or between a respective first cylinder support (9, 9’) and each respective inking cylinder support (17), so as to form an abutment for each inking cylinder (16) or for each inking cylinder support (17), structurally constraining and uniquely defining a relative position between the first axis (X1 ) and each inking axis (X5); wherein the method comprises the step e) of: setting the relative position between the first axis (X1 ) and each inking axis (X5), wherein step e) provides for moving each inking cylinder (16) towards the first cylinder (3) until each inking cylinder (16) or each inking cylinder support (17) abuts against the cam (6) and the at least one cam (6) is interposed between the first cylinder (3) and each inking cylinder (16), thus uniquely defining the relative position between the first axis (X1 ) and each inking axis (X5).

7. Method according to the preceding claim, wherein the cam (6) comprises a positioning seat or third positioning seat (18), wherein the third positioning seat (18) is configured to receive or abut against, a respective third coupling portion (26), wherein the respective inking cylinder (16) comprises the respective third coupling portion(26), or wherein the respective inking cylinder support (17) comprises the respective third coupling portion (26), so that when the cam (6) is clamped and interposed directly or indirectly between the first cylinder (3) and the second cylinder (4), and the third positioning seat (18) is in abutment against the respective third coupling portions, the relative position between the first axis (X1) and each inking axis (X5) is uniquely determined, wherein step e) provides for moving each inking cylinder (16) towards the first cylinder (3) until each respective third coupling portion (26) abuts against the third positioning seat (18) of the cam (6) and the at least one cam (6) is interposed between the first cylinder (3) and each inking cylinder (16), thus uniquely defining the relative position between the first axis (X1 ) and each inking axis (X5).

8. Method according to claim 7 and claim 3, wherein the third positioning seat (18) is the thickness that circumferentially delimits a circular semi-crown portion of the cam (6) coaxial with the respective first axis (X1), wherein the third coupling portion (26) is the thickness that circumferentially delimits a positioning disc or of a disc positioning portion connected to the respective inking cylinder (16) and / or to the respective inking cylinder support (17) coaxial with the respective inking axis (X5), wherein each first coupling portion (22) comprises a respective first cylindrical surface (24) extending around a first coupling portion axis which is parallel and / or coaxial to the first axis (X1), wherein the first positioning seat (13) comprises a first seat wall (19) wherein the first seat wall (19) is at least semi-cylindrical extending around a first seat axis which is parallel and / or coaxial to the first axis (X1) so as to accommodate the respective first cylindrical surface (24) coaxial and / or parallel to the first axis (X1), wherein each second coupling portion (23) comprises a respective second cylindrical surface (25) extending around a second coupling portion axis which is parallel and / or coaxial to the second axis (X2), wherein the second positioning seat (14) comprises a second seat wall (20) wherein the second seat wall (20) is at least semi-cylindrical extending around a second seat axis which is parallel and / or coaxial to the second axis (X2) so as to accommodate the respective second cylindrical surface (25) parallel and / or coaxial to the second axis (X2) during rotation of the second cylinder (4), wherein the at least one cam (6) is an enbloc element configured to provide stability and precision in the abutment of the first cylinder (3) and the second cylinder (4), and in the abutment of the inking cylinders and with the first cylinder (3).

9. Method according to any preceding claim, wherein the at least one cam (6) is an enbloc element configured to provide stability and precision inthe abutment of the first cylinder (3) and the second cylinder (4).

10. Method according to any preceding claim, wherein the first cylinder (3, 3’) and the second cylinder (4, 4’) are selected, based on the print format to be used in the printing unit (1), from a first format first cylinder (3) and a first format second cylinder (4), or a second format first cylinder (3’) and a second format second cylinder (4’), wherein the first format first cylinder (3) and the first format second cylinder (4) have a first format diameter and define a first print format and the print format distance (D) between the first axis (X1) of the first format first cylinder (3) and the second axis (X2) of the first format second cylinder (4) is a first print format distance (D1), and wherein the second format first cylinder (3’) and the second format second cylinder (4’) have a second format diameter and define a second print format and the print format distance (D) between the first axis (X1) of the second format first cylinder (3’) and the second axis (X2) of the second format second cylinder (4’) is a second print format distance (D2), wherein the first format diameter is greater or smaller than the second format diameter, wherein the at least one cam (6) is selected, based on the print format to be used in the printing unit (1 ), from a first format cam and a second format cam, wherein each first format cam is configured to be used with the first format first cylinder and the first format second cylinder, and each second format cam is configured to be used with the second format first cylinder and the second format second cylinder, wherein the method comprises the step of: f) varying the print format from the first print format to the second print format, or vice versa, wherein step f) provides for actuating each oscillating lever (11, 11’) towards the first angular position, and when each oscillating lever (11, 11’) is in the first angular position, separating the first format first cylinder (3) and the first format second cylinder (4), or the second format first cylinder (3’) and the second format second cylinder (4’), from the first cylinder supports (9, 9’) and from the second cylinder supports (10, 10’) and / or from the support structure (2), separating each first format cam or each second format cam from the support structure (2) and / or from the first cylinder supports (9, 9’), connecting and orienting each second format cam or each first format cam to the support structure (2) and / or to the first cylinder supports (9, 9’) repeating steps b) and c), connecting the second format first cylinder (3’) and the second format second cylinder (4’), or vice versa the first format first cylinder (3) and the first format second cylinder (4), to the first cylinder supports (9, 9’) and to the second cylinder supports (10, 10’) and / or from the support structure (2), wherein the method, after step f), provides for repeating step d) actuating each oscillating lever (11 , 11’) towards the second angular position, clamping each second format cam or each first format cam directly or indirectly between the first cylinder (3, 3’) and the second cylinder (4, 4’), defining thesecond print format distance (D2) between the first axis (X1) of the second format first cylinder (3’) and the second axis (X2) of the second format second cylinder (4’), or vice versa, defining the first print format distance (D1) between the first axis (X1 ) of the first format first cylinder (3) and the second axis (X2) of the first format second cylinder (4).

11. Method according to any preceding claim, wherein, after completing a printing cycle or in case of machine stoppage, the method comprises a disengagement step, wherein in the disengagement step, each oscillating lever (11 , 11’) is actuated in rotation towards a third angular position or disengagement angular position and wherein the second cylinder (4) is moved away from each cam (6) and is supported by each oscillating lever (11, 11’) in the third angular position without directly or indirectly contacting each cam (6), wherein the third angular position is between the first angular position and the second angular position, wherein, following the disengagement step, to start a new printing cycle, the method provides for actuating in rotation each oscillating lever (1 1, 11’) supporting the second cylinder (4), from the third angular position towards the at least one second angular position, moving the second axis (X2) along the circular trajectory towards the first axis (X1 ), until the cam (6) is clamped and interposed between the first cylinder (3) and the second cylinder (4).

12. Variable format offset type printing unit (1 ) for a variable print format offset printing machine (100), comprising-a support structure (2);-a pair of first cylinder supports (9, 9’), wherein the first cylinder supports (9, 9’) are connected to the support structure (2),- a first cylinder (3), wherein the first cylinder (3) is supported at its opposite ends in rotation about a first axis (X1) by the first cylinder supports (9, 9’), wherein the first cylinder (3) is a plate cylinder;- a pair of second cylinder supports (10, 10’),- a second cylinder (4), wherein the second cylinder (4) is supported at its opposite ends in rotation about a second axis (X2) by the second cylinder supports (10, 10’), wherein the second axis (X2) is parallel to the first axis (X1 ), wherein the second cylinder (4) is a transfer cylinder,- a pair of oscillating levers (11, 11’), wherein the oscillating levers (11, 11’) each support a second cylinder support (10, 10’) of the pair of second cylinder supports (10, 10’), wherein each oscillating lever (11 , 11’) is pivoted to the support structure (2) in rotation about an oscillation axis (X4) between a first angular position or format change angular position and at least one second angular position or print format angular position, and vice versa, such that when the second cylinder (4, 4’) is supported by the pair of second cylinder supports (10, 10’) the second axis (X2) is movable along a circular trajectory centred on the oscillation axis (X4), wherein the oscillation axis (X4) is parallel to the second axis (X2), wherein the oscillation axis (X4) is stationary and fixedrelative to the support structure (2), wherein, when each oscillating lever (11 , 11’) is in the second angular position, the second axis (X2) is positioned at the print format distance (D) from the first axis (X1 ) for printing on a material, wherein when each oscillating lever (11, 11 ’) is in the first angular position, the first cylinder (3) and the second cylinder (4) are spaced such that the second cylinder (4) and the first cylinder (3) can be separated from their respective first cylinder supports (10, 10’) and from their respective second cylinder supports (11, 11’) and replaced to vary the print format;-a third cylinder (5), wherein the third cylinder (5) is supported in rotation by the support structure (2) about a third axis (X3), wherein the third axis (X3) is parallel to the first axis (X1 ) and to the second axis (X2), wherein the third cylinder (5) is supported at its axial ends by respective eccentric or linear supports (21 , 21 ), wherein the third cylinder (5) is an impression cylinder, characterised in that the printing unit (1) comprises at least one cam (6, 6’), wherein the at least one cam (6, 6’) is connected to the first cylinder (3) or to one of the first cylinder supports (9, 9’) in a cantilever manner, directly or indirectly, from the first cylinder (3), wherein the at least one cam (6, 6’) is oriented and arranged along the circular trajectory along which the second axis (X2) is movable when the second cylinder (4) is supported by each oscillating lever (11 , 11’), so as to form a structural constraint that intercepts, directly or indirectly, the second cylinder (4) during rotation of each oscillating lever (11, 11’) towards the first axis (X1) from the respective first angular position, stopping or locking each oscillating lever (11 , 11’) in the at least one second angular position and uniquely defining the print format distance (D) between the second axis (X2) of the second cylinder (4) and the first axis (X1 ) of the first cylinder (3), wherein, when each oscillating lever (11 , 11’) is in the at least one second angular position supporting the second cylinder (4), the at least one cam (6) is clamped and interposed, directly or indirectly, between the first cylinder (3) and the second cylinder (4) under a thrust action of each oscillating lever (11, 11’) and the at least one cam (6) defines said structural constraint which prevents rotation of each oscillating lever (11, 11’) towards the first axis (X1), stopping or locking each oscillating lever (11, 11’) in the at least one second angular position, and wherein, when each oscillating lever (11 , 11’) is in the first angular position supporting the second cylinder (4), the at least one cam (6) is supported in a cantilever manner by the first cylinder (3) or by one of the first cylinder supports (9, 9’) spaced from the second cylinder (4) and from the second cylinder supports (10, 10’), without interfering with the second cylinder (4) and / or with the second cylinder supports (10, 10’).

13. Printing unit (1 ) according to the preceding claim, wherein the printing unit (1 ) further comprises an inking unit (15), wherein the inking unit (15) comprises at least one inking cylinder (16) supported in rotation about arespective inking cylinder axis (X5) by respective inking cylinder supports (17), wherein each inking axis (X5) is parallel to the first axis (X1), wherein the inking unit (15) comprises thrust actuators configured to move the inking axis (X5) closer to or farther from the first axis (X1), wherein the at least one cam (6) is interposed, directly or indirectly, between the first cylinder (3) and each inking cylinder (16), without interfering with the rotation of the first cylinder (3) and each inking cylinder (16) respectively about the first axis (X1) and each respective inking cylinder axis (X5), wherein the at least one cam (6) defines an abutment against which each inking cylinder (16) is, directly or indirectly, in abutment under a thrust action of said thrust actuators, which prevents the thrust actuators from further moving the inking axis (X5) towards the first axis (X1), thus uniquely defining the relative position between the first axis (X1) and each inking axis (X5).

14. Printing unit (1) according to any of the preceding claims from 12 to 13, wherein the at least one cam (6) comprises a first positioning seat (13) and a second positioning seat (14), wherein the first positioning seat (13) is shaped to accommodate, a respective first coupling portion (22), wherein the first cylinder (3) comprises the respective first coupling portion (22) at a stationary end portion of the first cylinder, so that the cam can be directly interposed against the first cylinder (3), against the stationary end portion of the first cylinder without interfering with the rotation of the first cylinder (3) about the first axis (X1 ), or wherein each of the respective first cylinder supports (9, 9’) comprises the respective first coupling portion (22), wherein the respective first cylinder supports (9, 9’) are configured to rotatably support respective ends of the first cylinder (9), so that the cam (6) can be indirectly interposed against the first cylinder (3) via at least one of the respective first cylinder supports (9, 9’), wherein the second positioning seat (14) is shaped to accommodate, a respective second coupling portion (23), wherein the second cylinder (4) comprises the respective second coupling portion (23) at a stationary end portion of the second cylinder, so that the cam (6) can be directly interposed against the second cylinder (4), against a second cylinder stationary end portion thereof, without interfering with the rotation of the second cylinder (4) about the second axis (X2), or wherein each of the second cylinder supports (10, 10’), which are connected to the respective oscillating lever (11 , 11’), comprises the respective second coupling portion (23), wherein the second cylinder supports (10, 10’) are configured to rotatably support respective ends of the second cylinder (4), so that the cam (6) can be indirectly interposed against the second cylinder (4) via at least one of the respective second cylinder supports (10, 10’),wherein the at least one cam (6) is clamped in abutment between the first coupling portion (22) and the second coupling portion (23) respectively accommodated in the first positioning seat (13) and in the second positioning seat (14), avoiding interference with the rotation of the first cylinder (3) and the second cylinder (4) respectively about the first axis (X1) and the second axis (X2).

15. Printing unit (1) according to the preceding claim, wherein each first coupling portion (22) comprises a respective first cylindrical surface (24) extending around a first coupling portion axis which is parallel and / or coaxial to the first axis (X1), wherein each second coupling portion (23) comprises a respective second cylindrical surface (25) extending around a second coupling portion axis which is parallel and / or coaxial to the second axis (X2), wherein the first positioning seat (13) comprises a first seat wall (19) wherein the first seat wall (19) is at least semi-cylindrical extending around a first seat axis which is parallel and / or coaxial to the first axis (X1 ) so as to accommodate the respective first cylindrical surface (24) coaxial and / or parallel to the first axis (X1), wherein the second positioning seat (14) comprises a second seat wall (20) wherein the second seat wall (20) is at least semi-cylindrical extending around a second seat axis which is parallel and / or coaxial to the second axis (X2) so as to accommodate the respective second cylindrical surface (25) parallel and / or coaxial to the second axis (X2).

16. Printing unit (1) according to the preceding claim, wherein the first seat wall (19) is cylindrical delimiting a through-hole coaxial with the first axis (X1 ), such that the respective first cylindrical surface (24) is insertable or fittable into the first positioning seat (13), wherein the second seat wall (20) is concave semi-cylindrical and / or subtends a central angle with respect to the second seat axis between 20° and 180°, preferably 90°, suitable for accommodating the respective second cylindrical surface (25) coaxial to the second axis (X2).

17. Printing unit (1) according to any of the preceding claims from 15 to 16, wherein the first seat wall (19) has a first wall radius (R1 ) greater than or equal to the radius of the first cylindrical surface (r1 ) of the respective first cylindrical surface (24), wherein the second seat wall (20) has a second wall radius (R2) greater than or equal to the radius of the first cylindrical surface (r2) of the respective second cylindrical surface (25).

18. Printing unit (1) according to claim 13, wherein the cam (6) comprises a third positioning seat (18) configured to receive or abut against a respective third coupling portion (26), wherein the respective inking cylinder (16) comprises the respective third coupling portion (26), or wherein the respective inking cylinder support (17) comprises the respective third coupling portion(26), such that when the cam (6) is clamped and interposed directly or indirectly between the first cylinder (3) and the second cylinder (4), and the third positioning seat (18) is in abutment against the respective third coupling portions, the relative position between the first axis (X1) and each inking axis (X5) is uniquely determined.

19. Printing unit (1) according to the preceding claim, wherein the third positioning seat (18) comprises a third seat wall (30) which is at least partially cylindrical, wherein the third seat wall (30) is coaxial to the first axis (X1), configured to abut against each respective third coupling portion (26), wherein each third coupling portion (26) comprises a third cylindrical surface (29) coaxial to the respective inking axis (X5) configured to abut with the third positioning seat (18).

20. Printing unit (1) according to the preceding claim, wherein the third coupling portion (26) is the thickness that circumferentially delimits a positioning disc or positioning portion connected to the respective inking cylinder (16) and / or to the respective inking cylinder support (17) coaxial to the respective inking axis (X5), wherein the second positioning seat (18) is the thickness that circumferentially delimits a circular semicrown portion of the cam (6).

21. Printing unit (1) according to any of the preceding claims from 12 to 20, comprising at least one thrust device (12) configured to push the at least one oscillating lever (11 , 11’) in oscillation about the oscillation axis (X4), and so as to move the second cylinder (4) and the second axis (X2) along the circular trajectory to constantly clamp the at least one cam (6) interposed directly or indirectly between the first cylinder (3) and the second cylinder (4), preferably the thrust device (12) is of the hydraulic or pneumatic type, avoiding the inclusion of systems for converting rotary motion into linear motion, such as for example screw-nut systems.

22. Variable print format offset printing machine (100), comprising at least one printing unit (1) according to any of the preceding claims from 12 to 21.

23. Cam (6) for a variable format offset type printing unit (1), wherein the printing unit (1 ) comprises-a support structure (2);-a pair of first cylinder supports (9, 9’), wherein the first cylinder supports (9, 9’) are connected to the support structure (2),-a first cylinder (3, 3’), wherein the first cylinder (3, 3’) is supported at its opposite ends in rotation about a first axis (X1) by the first cylinder supports (9, 9’), wherein the first cylinder (3, 3’) is a plate cylinder;-a pair of second cylinder supports (10, 10’),-a second cylinder (4, 4’), wherein the second cylinder (4, 4’) is supported at its opposite ends in rotation about a second axis (X2) by the second cylinder supports (10, 10’), wherein the second axis (X2) is parallel to the first axis (X1), wherein the second cylinder (4, 4’) is a transfer cylinder,- a pair of oscillating levers (11, 11’), wherein the oscillating levers (11, 11’) each support a second cylinder support (10, 10’) of the pair of second cylinder supports (10, 10’), wherein each oscillating lever (11 , 11’) is pivoted to the support structure (2) in rotation about an oscillation axis (X4) between a first angular position or format change angular position and at least one second angular position or print format angular position, and vice versa, such that when the second cylinder (4, 4’) is supported by the pair of second cylinder supports (10, 10’) the second axis (X2) is movable along a circular trajectory centred on the oscillation axis (X4), wherein the oscillation axis (X4) is parallel to the second axis (X2), wherein, when each oscillating lever (11, 11’) is in the second angular position, the second axis (X2) is positioned at the print format distance (D) from the first axis (X1 ), wherein when each oscillating lever (11, 11’) is in the first angular position, the first cylinder (3, 3’) and the second cylinder (4, 4’) are spaced such that the second cylinder (4, 4’) and the first cylinder (3, 3’) can be separated from their respective first cylinder supports (10, 10’) and from their respective second cylinder supports (11, 11’) and replaced to vary the print format;-a third cylinder (5), wherein the third cylinder (5) is supported in rotation by the support structure (2) about a third axis (X3), wherein the third axis (X3) is parallel to the first axis (X1 ) and to the second axis (X2), wherein the third cylinder (5) is supported at its axial ends by respective eccentric or linear supports (21 , 21 ), wherein the third cylinder (5) is an impression cylinder, characterised in that the cam (6) comprises a shaped body, wherein the shaped body of the cam (6) comprises:-a first positioning seat (13), wherein the first positioning seat (13) is configured to be connected and constrained to a stationary portion of the first cylinder (3) or to one of the first cylinders supports (9, 9’), and-a second positioning seat (14), wherein the second positioning seat (14) is configured to form an abutment for a stationary portion of the second cylinder (4) or for one of the second cylinders supports (10, 10’), such that when the first positioning seat (13) is connected and constrained directly or indirectly to the first cylinder (3), the cam (6) protrudes in a cantilever manner along a direction perpendicular to the first axis (X1) with the second positioning seat (14) oriented to intercept the circular trajectory along which the second axis (X2) is movable when the second cylinder (4) is supported by each oscillating lever (11, 11’), to form a structural constraint that intercepts, directly or indirectly, the second cylinder(4) or one of its second cylinder supports (10, 10’) during rotation of each oscillating lever (11 , 11’) towards the first axis (X1 ) from the respective first angular position and against which, directly or indirectly, the second cylinder (4) or one of its second cylinder supports (10, 10’) abuts, stopping or locking each oscillating lever (11 , 11’) in the at least one second angular position and uniquely setting the print format distance (D) between the second axis (X2) of the second cylinder (4) and the first axis (X1) of the first cylinder (3).

24. Cam (6) according to the preceding claim, wherein the first positioning seat (13) has a first seat axis which is coaxial to the first axis (X1), wherein the second positioning seat (14) has a second seat axis which is parallel to the second seat axis, wherein the first positioning seat (13) delimits a through-hole coaxial with the first axis (X1 ) which is shaped so as to shape-fit or be fitted onto the stationary portion of the first cylinder (3) or onto said one of the first cylinder supports (9, 9’), wherein the second positioning seat (14) is an open concave seat comprising an open cylindrical surface extending around the second seat axis and subtending a central angle with respect to the second seat axis between 20° and 180°, so as to form said abutment for the stationary portion of the second cylinder (4) or for said one of the second cylinder supports (10, 10’) during rotation of the oscillating levers (11 , 11’) towards the first axis (X1) and such as not to obstruct the movement away of the second cylinder (4) and the second cylinder support (10, 10’) during rotation of the oscillating levers (11 , 11’) towards the first angular position.

25. Cam (6) according to any of the preceding claims from 23 to 24, wherein the at least one cam (6) is an enbloc element configured to provide stability and precision in the abutment of the first cylinder (3) and the second cylinder (4), wherein the cam (6) comprises an elongated central cam portion that connects the first positioning seat (13) and the second positioning seat (14), uniquely, without including adjustment means for adjusting the mutual distance or orientation between the first positioning seat (13) and the second positioning seat (14).

26. Cam (6) according to any of the preceding claims from 23 to 25, wherein the printing unit (1 ) comprises an inking unit (15), wherein the inking unit (15) comprises at least one inking cylinder (16) supported in rotation about a respective inking cylinder axis (X5) by respective inking cylinder supports (17), wherein each inking axis (X5) is parallel to the first axis (X1 ), wherein the inking unit (15) comprises thrust actuators configured to adjust the distance between the inking axis (X5) and the first axis (X1 ),wherein the at least one cam (6) is also configured to be interposed directly between the first cylinder (3) and each inking cylinder (16), without interfering with the rotation of the first cylinder (3) and of each inking cylinder (16), or between a respective first cylinder support (9, 9’) and each respective inking cylinder support (17), so as to form a structural constraint that uniquely defines a relative position between the first axis (X1 ) and each inking axis (X5), forming an abutment for each inking cylinder (16) or for each inking cylinder support (17), wherein the shaped body of the cam (6) comprises a positioning seat or third positioning seat (18), wherein the third positioning seat (18) is configured to receive or abut against a respective third coupling portion (26), wherein the third positioning seat (18) is an abutment portion against which each inking cylinder (16) or each inking cylinder support (17) abuts, and the at least one cam (6) is configured to be interposed between the first cylinder (3) and each inking cylinder (16), thus uniquely defining the relative position between the first axis (X1 ) and each inking axis (X5), wherein the cam (6) is an enbloc element configured to provide stability and precision in the abutment of the first cylinder (3) and the second cylinder (4), and in the abutment of the inking cylinders (16) against the first cylinder (3).

27. Cam (6) according to any of the preceding claims from 23 to 26, wherein the shaped body of the cam (6) comprises at least one orientation fixing seat (32), wherein the orientation fixing seat (32) is configured to receive a positioning pin (36), wherein the positioning pin (36) is connected and / or connectable to the respective first cylinder support (9, 9’) and / or to the support structure (2), so that when the first positioning seat (13) is connected directly or indirectly to the first cylinder (3) and the orientation fixing seat (32) is connected to the positioning pin (36), the cam (6) is supported and uniquely oriented by the respective first cylinder support (9, 9’) and / or by the support structure (2).

28. Cam (6) according to the preceding claim, wherein the cam (6) comprises an elastic locking device (35), wherein the elastic locking device (35) is housed in the orientation fixing seat (32), wherein the elastic locking device (35) is configured to elastically retain the positioning pin (13) in the orientation fixing seat (32) so as to elastically and reversibly lock the axial position of the cam (6) along the direction parallel to the first axis (X1 ).

29. Cam (6) according to the preceding claim, wherein the at least one orientation fixing seat (32) comprises a first hole or axial hole (33) at least partially made along a direction parallel to the first axis (X1), when the cam (6) is connected to the printing unit (1 ), wherein the axial hole (33) is configured to receive the positioning pin (36), wherein the at least one orientation fixing seat (32) comprises a second hole or radial hole (34) made along a direction perpendicular to the direction along which the axial hole (33) is made, wherein the axial hole (33) and the radial hole (34) are communicating,wherein the elastic locking device (35) is housed in the radial hole (34), wherein the elastic locking device (35) is configured to elastically retain the positioning pin (13) in the axial hole (33), wherein the positioning pin (13) has a groove (37), which forms a recess in the positioning pin (13), wherein the elastic locking device (35) comprises an interference element (38), such as a ball, movable along the direction along which the radial hole (34) is made between a retracted position and a maximum interference position, wherein the interference element (38) is constantly urged into the maximum interference position by an elastic element (39), such as a spring, wherein during insertion of the positioning pin (13) into the axial hole (33), the positioning pin (13) interferes with the interference element (38) pushing it towards the retracted position against the action of the elastic element (39), until the interference element (38) enters the groove (37) of the positioning pin (36) urged into the maximum interference position by the action of the elastic element (39), so as to elastically and reversibly lock the axial position of the cam (6) along the direction parallel to the first axis (X1).

30. Kit of cams for a variable format offset printing unit, comprising, a first cam or first format cam according to any of the claims from 23 to 29, and at least one second cam or second format cam according to any of the claims from 23 to 29, wherein the first cylinder (3, 3’) and the second cylinder (4, 4’) are selected, based on the print format to be used in the printing unit (1 ), from a first format first cylinder (3) and a first format second cylinder (4), or a second format first cylinder (3’) and a second format second cylinder (4’), wherein the first format first cylinder (3) and the first format second cylinder (4) have a first format diameter and define a first print format and the print format distance (D) between the first axis (X1) of the first format first cylinder (3) and the second axis (X2) of the first format second cylinder (4) is a first print format distance (D1 ), and wherein the second format first cylinder (3’) and the second format second cylinder (4’) have a second format diameter and define a second print format and the print format distance (D) between the first axis (X1) of the second format first cylinder (3’) and the second axis (X2) of the second format second cylinder (4’) is a second print format distance (D2), wherein the first format diameter is greater or smaller than the second format diameter, wherein each first format cam is configured to be used with the first format first cylinder (3) and the first format second cylinder (4), and each second format cam is configured to be used with the second format first cylinder (3’) and the second format second cylinder (4’), wherein the shaped body of the first cam is shaped to set the first print format distance (D1 ) between the first axis (X1) and the second axis (X2) when the first cam is mounted on the printing unit (1 ) together with the first format first cylinder (3) and the first format second cylinder (4), wherein theshaped body of the first cam is adapted to be interposed between the first format first cylinder (3) and the first format second cylinder (4), or between one of the first cylinder supports (9, 9’) and one of the second cylinder supports (10, 10’), and wherein the shaped body of the second cam is shaped to set the second print format distance (D2) between the first axis (X1) and the second axis (X2) when the second cam is mounted on the printing unit (1) together with the second format first cylinder (3’) and the second format second cylinder (4’), wherein the shaped body of the second cam is adapted to be interposed between the second format first cylinder (3’) and the second format second cylinder (4’), or between one of the first cylinder supports (9, 9’) and one of the second cylinder supports (10, 10’), wherein the second print format distance (D2) is greater than the first print format distance (D1 ), wherein the second format diameter is greater than the first format diameter.

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