FIELD OF THE INVENTION

The present invention relates to the technical sector concerning cutting machines for cutting material in sheet or roll form, such as leathers, skins, synthetic leathers, etc.

In particular, the present invention relates to a pneumatic cutting device having an oscillating blade able to be used and mounted onthe cutting machines. DESCRIPTION OF THE PRIOR ART

In this particular sector cutting machines comprise a frame, situated above a work plane when the materials to be cut, such as for example skins (leathers, skins), the synthetic leathers and the like, a cutting machine inferiorly provided with a cutting blade and movement means, borne by the frame and mobile with respect thereto, for moving the cutting device according to the three Cartesian axis above the work plane and positioning it above the material to be cut so that the cutting blade can be activated for cutting the material and being moved according to a given cutting pathway for cutting the material on the basis of profiles and/or predetermined or desired profiles. The cutting devices used for this purpose are predisposed so that the cutting blade can be made to oscillate vertically during the cutting of the material, from a lower cutting position to an upper cutting position, always remaining within the thickness of the material to be scored/cut.

A type of cutting device at present used includes causing the cutting blade to oscillate vertically by means of a pneumatic activating mechanism.

The known pneumatic cutting devices, i.e. with a pneumatic activation for vertical oscillation of the cutting blade, comprise an oscillating chamber, having an upper travel limit wall and a lower travel limit wall, an oscillating piston, predisposed with the head thereof in the oscillating chamber and with the relative stem connected to the cutting blade, and a pneumatic activating system, connected to a compressed air source, comprising a discharge and communicating with the oscillating chamber for oscillating the piston in the oscillating chamber between the lower stroke limit wall and the upper stroke limit wall, and therefore for vertically oscillating the cutting blade between a lower cutting position and an upper cutting position.

Usually, the pneumatic activating system and the discharge are predisposed and configured so that the part of the oscillating chamber comprised between the head of the piston and the upper stroke limit wall and the part of the oscillating chamber comprised between the head of the piston and the lower stroke limit wall are made alternatively communicating with the compressed air source and the discharge in order to make the oscillation of the piston in the oscillating chamber possible.

In particular, when the compressed air source is placed in communication with the part of the oscillating chamber comprised between the head of the piston and the upper stroke limit wall, the part of the oscillating chamber comprised between the head of the piston and the lower stroke limit wall is in communication with the discharge, in this case the piston is pneumatically pushed downwards; while when the compressed air source is placed in communication with the part of the oscillating chamber comprised between the piston head and the lower stroke limit wall, the part of the oscillating chamber comprised between the piston head and the upper stroke limit wall is in communication with the discharge, in this case the piston is pneumatically pushed upward, thus generating an oscillating motion in the oscillating chamber and the vertical oscillation of the cutting blade between the lower cutting position and the upper cutting position.

In this regard, the oscillating chamber comprises two openings and the pneumatic activating system comprises conduits, communicating with the openings and with a shutter or another valve organ such as to make each of the two openings of the oscillating chamber, via the conduits, alternatively communicating with the compressed air source and the discharge. In these pneumatic cutting devices, therefore, the entity of the oscillation stroke of the oscillating piston is determined by the dimensions of the oscillating chamber, i.e. the distance existing between the upper stroke limit wall and the lower stroke limit wall: consequently the entity of the stroke of the oscillating piston in the oscillating chamber determines and imposes a limit on the entity of the vertical oscillation stroke of the cutting blade between the lower cutting position and the upper cutting position.

This can constitute a drawback.

In fact there is frequently a need to carry out the cutting operations on materials, in particular leather sheets, skins, leather, synthetic leathers, having different thicknesses with respect to one another, even having thicknesses of significantly different entity.

For example, in the case of skins, the thickness of the skin on which the cutting operations are to be carried out can vary from 1 to 3 mm, even up to 4 mm.

Therefore it is clear that a pneumatic cutting device comprising a piston that oscillates in an oscillating chamber which imparts only one predefined entity of the vertical oscillation travel of the cutting blade is poorly adapted to work operations with skins of different thicknesses. For example, a pneumatic cutting device having an oscillating chamber in which the distance between the lower stroke limit wall and the upper stroke limit wall imposes an oscillation travel of the oscillating piston internally thereof of 2 mm, i.e. an entity of the oscillation travel of the cutting blade between the lower cutting position and the upper cutting position of a maximum of 2 mm can be used for the cut of leather sheets having a thickness of up to 2 mm, but cannot be used for the cutting of leather sheets having a greater thickness, for example up to 3 or 4 mm.

At present, therefore, when cutting operations are to be carried out on leathers having different thicknesses to one another, time by time a replacement of the pneumatic cutting device is carried out with another predisposed with an oscillating chamber having suitable dimensions for the entity of the vertical oscillation travel of the cutting blade requested by the thickness of the leather sheets.

SUMMARY OF THE INVENTION An aim of the present invention is therefore to make available a new pneumatic cutting device having an oscillating blade for leather cutting machines able to obviate the above-mentioned drawbacks present in the prior art devices.

In particular, an aim of the present invention is therefore to make available a new pneumatic cutting device having an oscillating blade able to carry out the cutting operations on leather sheets of different thicknesses without requiring any replacement of parts or components.

The above-mentioned aim is attained by a pneumatic cutting device with an oscillating blade for leather cutting machines according to the contents of claim 1.

Other advantageous aspects of the cutting device with oscillating blade proposed by the present invention are set down in the various relative dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS The characteristics of the pneumatic cutting device with oscillating blade for leather cutting machines proposed by the invention are described in the following with reference to the accompanying tables of drawings, wherein:

- figures 1A and 1 B illustrate, in a front view from a first angle, the pneumatic cutting device with oscillating blade for leather cutting machines that is the object of the invention, represented in a first possible activating modality for cutting a first leather sheet having a given thickness, and with the cutting blade illustrated in two distinct operating configurations during oscillating activation thereof for cutting the first leather sheet, with figure 1A illustrating the lower cutting position reachable by the cutting blade during oscillation thereof, while figure 1 B illustrates a first upper cutting position reachable by the cutting blade during oscillation thereof;

- figures 1 C and 1 D also illustrate the pneumatic cutting device with oscillating blade of the invention in a front view from a different angle with respect to the angle of figures 1A and 1 B, represented in a second possible activating modality for cutting a second leather sheet having a greater thickness than the first sheet of figures 1A and 1 B, and with the cutting blade illustrated in two distinct operating configurations during oscillating activation thereof for cutting the second leather sheet, with figure 1 C illustrating the lower cutting position reachable by the cutting blade during oscillation thereof, while figure 1 D illustrates a second upper cutting position reachable by the cutting blade during oscillation thereof, being higher than the first upper cutting position illustrated in figure 1 B;

- figure 2A illustrates the pneumatic cutting device of the invention according to a plan view;

- figure 2B is a front view of the device of figure 2A illustrated in the configuration of figure 1A, i.e. represented in the first activating mode with the cutting blade illustrated in the lower cutting position;

- figure 2C is a view along section plane l-l of figure 2B, in a slightly larger scale with respect to figure 2B;

- figure 2D represents, in a considerably larger scale, the detail denoted by the letter H in figure 2C;

- figure 2E is a front view of the cutting device of figure 2A illustrated in the configuration of figure 1 B, i.e. represented in the first activating mode with the cutting blade illustrated in the upper cutting position;

- figure 2F is a view along section plane ll-ll of figure 2E, in a slightly larger scale;

- figure 2G represents, in a considerably larger scale, the detail denoted by the letter K in figure 2F; - figure 3A illustrates the pneumatic cutting device of the invention according to a plan view with a different orientation with respect to the orientation of figure 2 A;

- figure 3B is a front view of the device of figure 3A illustrated in the configuration of figure 1C, i.e. represented in the second activating mode with the cutting blade illustrated in the lower cutting position;

- figure 3C is a view along section plane Ill-Ill of figure 3B, in a slightly larger scale with respect to figure 3B;

- figure 3D represents, in a considerably larger scale, the detail denoted by the letter H' in figure 3C;

- figure 3E is a front view of the cutting device of figure 3A illustrated in the configuration of figure 1 D, i.e. represented in the second activating mode with the cutting blade illustrated in the second upper cutting position;

- figure 3F is a view along section plane IV-IV of figure 3E, in a slightly larger scale;

- figure 3G represents, in a considerably larger scale, the detail denoted by the letter K' in figure 3F.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the appended tables of drawings, reference numeral (100) denotes the pneumatic cutting device having an oscillating blade for leather cutting machines that is the object of the present invention in its entirety.

The cutting blade (100) comprises a body (C); a cutting blade (L) for cutting a leather sheet (V1 , V2) (or another like material in sheet or roll form, such as leather or synthetic materials) stretched on a work plane (PL). In this regard, the cutting device (100) is mountable on cutting machines, for example numerically controlled.

The cutting device (100) comprises a stem (14) which bears the cutting blade (L) and is predisposed slidably internally of the body (C); a first oscillating chamber (1 ) internally of the body (C) comprising an upper stroke limit wall

(1 1 ) and a lower stroke limit wall (12), and a first oscillating piston (10), mounted on the stem (14), and which is predisposed in the first oscillating chamber (1 ), between the upper stroke limit wall (1 1 ) and the lower stroke limit wall (12) (see for example figures 2C and 2F).

The first oscillating chamber (1 ) is dimensioned so that the upper stroke limit wall (1 1 ) and the lower stroke limit wall (12) are distanced from one another by a first distance (d1 ) (see for example figures 2D and 2G). The cutting device (100) comprises a first pneumatic activating system (P1 ), connectable to a compressed air source (A1 ), which communicates with the first oscillating chamber (1 ) and comprises at least a discharge (S1 , S2).

The first pneumatic activating system (P1 ) and the at least a discharge (S1 , S2) are predisposed in the body (C) and configured so that, when the first pneumatic activating system (P1 ) is connected to a compressed air source (A1 ), and the compressed air source (A1 ) is activated, a first part (1A) of the first oscillating chamber (1 ) comprised between the first oscillating piston (10) and the lower stroke limit wall (12) and a second part (1 B) of the first oscillating chamber (1 ) comprised between the first oscillating piston (10) and the upper stroke limit wall (1 1 ) are placed in communication alternatively with the compressed air source (A1 ) and the at least a discharge (S1 , S2).

In this way, the first oscillating piston (10) is pneumatically activated so as to oscillate in the first oscillating chamber (1 ), between the lower stroke limit wall

(12) and the upper stroke limit wall (1 1 ), and therefore cause the cutting blade (L) to oscillate vertically by a first entity of vertical oscillation at most corresponding to the distance (d1 ) between the lower stroke limit wall (12) and the upper stroke limit wall (1 1 ), between a lower cutting position (L1 ) and a first upper cutting position (L2) in order to be able to carry out cutting operations of leathers (V1 ) having a maximum thickness (ml ) not greater than the first distance (d1 ) (see figures 1A and 1 B). In fact, when the first part (1A) of the first oscillating chamber (1 ) (comprised between the first oscillating piston (10) and the lower stroke limit wall (12) of the first oscillating chamber (1 )) is in communication, through the first pneumatic activating system (P1 ), with the compressed air source (A1 ), the second part (1 B) of the first oscillating chamber (1 ) (comprised between the first oscillating piston (10) and the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 )) is in communication with the at least a discharge (S1 , S2) of the first pneumatic activating system (P1 ), so that the first oscillating piston (10) can be pneumatically pushed upwards [see for example figures 2C and 2D which illustrate this situation, with the first oscillating piston (10), which is in contact with the lower stroke limit wall (12) of the first oscillating chamber (1), and therefore in the condition of being pushed upwards, i.e. towards the upper stroke limit wall (11) of the first oscillating chamber (1) by the compressed air flow coming from the compressed air source (A 1)J. In a specular fashion, when the first part (1A) of the first oscillating chamber (1 ) (comprised between the first oscillating piston (10) and the lower stroke limit wall (12) of the first oscillating chamber (1 )) is in communication with the at least a discharge (S1 , S2) of the first pneumatic activating system (P1 ), the second part (1 B) of the first oscillating chamber (1 ) (comprised between the first oscillating piston (10) and the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 )) is in communication, by means of the first pneumatic activating system (P1 ), with the compressed air source (A1 ), so that the first oscillating piston (10) can be pneumatically pushed downwards [see for example figures 2F and 2G which illustrate this situation, with the first oscillating piston (10), which is in contact with the upper stroke limit wall (11) of the first oscillating chamber (1), and therefore in the condition of being pushed downwards, i.e. towards the lower stroke limit wall (12) of the first oscillating chamber (1), by the compressed air flow coming from the compressed air source (A 1)J. The peculiarities of the cutting device (100) of the present invention consist in the fact that it comprises a second oscillating chamber (2), also predisposed internally of the body (C), arranged superiorly of the first oscillating chamber (1 ), and having an upper stroke limit surface (21 ) and a lower stroke limit surface (22); a second oscillating piston (20), mounted on the stem (14), and which is predisposed in the second oscillating chamber (2), between the upper stroke limit surface (21 ) and the lower stroke limit surface (22). In particular, the second oscillating chamber (2) is dimensioned so that the upper stroke limit surface (21 ) and the lower stroke limit surface (22) are distanced from one another by a second distance (d2) greater than the first distance (d1 ) by which the upper stroke limit wall (1 1 ) and the lower stroke limit wall (12) of the first oscillating chamber (1 ) are mutually distanced (see for example figures 3D and 3G).

The cutting device (100) further has a second pneumatic activating system (P2), connectable to a compressed air source (A2), which communicates with the second oscillating chamber (2) and comprises at least a discharge (S3, S4). In particular, the second pneumatic activating system (P2), and the at least a discharge (S3, S4) are predisposed in the body (C) and are configured so that, when the second pneumatic activating system (P2) is connected to a compressed air source (A2), and this compressed air source (A2) is activated, a first part (2A) of the second oscillating chamber (2) comprised between the second oscillating piston (20) and the lower stroke limit surface (22) and a second part (2B) of the second oscillating chamber (2) comprised between the second oscillating piston (20) and the upper stroke limit surface (21 ) are placed in communication alternatively with the compressed air source (A2) and the at least a discharge (S3, S4). In this way, the second oscillating piston (20) is pneumatically activated to oscillate in the second oscillating chamber (2), between the lower stroke limit surface (22) and the upper stroke limit surface (21 ), and therefore cause the cutting blade (L) to be oscillated vertically with a second entity of vertical oscillation at most corresponding to the distance (d2) between the lower stroke limit surface (22) and the upper stroke limit surface (21 ), between a lower cutting position (L1 ) and a second upper cutting position (Ι_2') at a greater height than the first upper cutting position (L2) with respect to the work plane (PL) in order to be able to carry out cutting operations of leathers (V2) having a maximum thickness (m2) not greater than (d2) (see figures 1 C and 1 D). In fact, when the first part (2A) of the first oscillating chamber (2) (comprised between the second oscillating piston (20) and the lower stroke limit surface (22) of the second oscillating chamber (2)) is in communication, through the second pneumatic activating system (P2), with the compressed air source (A2), the second part (2B) of the second oscillating chamber (2) (between the second oscillating piston (20) and the upper stroke limit surface (21 ) of the second oscillating chamber (2)) is in communication with the at least a discharge (S3, S4) of the second pneumatic activating system (P2), so that second oscillating chamber (20) can be pneumatically pushed upwards [see for example figures 3C and 3D which illustrate this situation, with the second oscillating piston (20), which is in contact with the lower stroke limit surface (22) of the second oscillating chamber (2), and therefore in the condition of being pushed upwards, i.e. towards the upper stroke limit surface (21) of the second oscillating chamber (2) by the compressed air flow coming from the compressed air source (A2)],

In a specular fashion, when the first part (2A) of the second oscillating chamber (2) (comprised between the second oscillating piston (20) and the lower stroke limit surface (22) of the second oscillating chamber (2)) is in communication with the at least a discharge (S3, S4) of the second pneumatic activating system (P2), the second part (2B) of the second oscillating chamber (2) (comprised between the second oscillating piston (20) and the upper stroke limit surface (21 ) of the second oscillating chamber (2)) is in communication, through the second pneumatic activating system (P2), with the compressed air source (A2), so that the second oscillating piston (20) can be pneumatically pushed downwards [see for example figures 3F and 3G which illustrate this situation, with the second oscillating piston (20), which is in contact with the upper stroke limit surface (21) of the second oscillating chamber (2), and therefore in the condition of being pushed downwards, i.e. towards the lower stroke limit surface (22) of the second oscillating chamber (2) by the compressed air flow coming from the compressed air source (A2)].

An aspect of particular significance of the cutting device (100) of the invention consists in the fact that the first pneumatic activating system (P1 ) and the second pneumatic activating system (P2) are independent of one another, in the sense that they are predisposed internally of the body (C) so as to be alternatively connectable to a compressed air source (A1 , A2), so that the first oscillating chamber (1 ) and the second oscillating chamber (2) are alternatively placed in communication, singly and one at a time, to the compressed air source (A1 , A2).

Therefore, when the first pneumatic activating system (P1 ) is connected to the compressed air source (A1 ), and this compressed air source (A1) is activated, the cutting device (100) is able to pneumatically activate the first oscillating piston (10) to oscillate in the first oscillating chamber (1 ), between the relative lower stroke limit wall (12) and the relative upper stroke limit wall (1 1 ), and consequently cause the cutting blade (L) to oscillate vertically.

In particular, the cutting blade (L) is thus made to oscillate vertically between a lower cutting position (L1 ) (see figures 1A, 2B, 2C, 2D), defined when the first oscillating piston (10) reaches abutment against the lower stroke limit wall (12) of the first oscillating chamber (1 ), and a first upper cutting position (L2) (see figures 1 B, 2E, 2F, 2G), defined when the first oscillating piston (10) reaches abutment against the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ).

In this way, the cutting blade (L) is made to oscillate vertically by a first entity of vertical oscillation at most corresponding to the distance (d1 ) between the lower stroke limit wall (12) and the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ), in order to be able to carry out cutting operations of leathers (V1 ) having a maximum thickness (ml ) not greater than (d1 ) (see figures 1A and 1 B). Instead, when the second pneumatic activating system (P2) is connected to the compressed air source (A2), and this compressed air source (A2) is activated, the cutting device (100) is able to pneumatically activate the second oscillating piston (20) to oscillate in the second oscillating chamber (2), between the relative lower stroke limit surface (22) and the relative upper stroke limit surface (21), and consequently cause the cutting blade (L) to oscillate vertically.

In particular, the cutting blade (L) is thus made to oscillate vertically between a lower cutting position (L1 ) (see figures 1C, 3B, 3C, 3D), defined when the second oscillating piston (20) reaches abutment against the lower stroke limit surface (22) of the second oscillating chamber (2), and a second upper cutting position (L2) (see figures D, 3E, 3F, 3G), defined when the second oscillating piston (20) reaches abutment against the upper stroke limit surface (21) of the second oscillating chamber (2).

In this way, the cutting blade (L) is made to oscillate vertically with a second entity of vertical oscillation at most corresponding to the distance (d2) between the lower stroke limit surface (22) and the upper stroke limit surface (21 ) of the second oscillating chamber (2), between a lower cutting position (L1) and a second upper cutting position (Ι_2') at a greater height than the first upper cutting position (L2) with respect to the work plane (PL) in order to be able to carry out cutting operations of leathers (V2) having a maximum thickness (m2) not greater than (d2) (see figures 1 C and 1 D).

In order to be able to activate the cutting blade (L) with these two possible vertical oscillations with two different entities of vertical oscillation (the second greater than the first), when the two pneumatic activating systems are activated alternatively to one another, i.e. when the two oscillating pistons are pneumatically activated alternatingly, in turn one at a time, to oscillate in the relative oscillating chamber, a further fundamental aspect and specification of the cutting device ( 00) of the invention consists in the particular way the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ) is configured and predisposed internally of the body (C).

In fact, the upper stroke limit wall (11) of the first oscillating chamber (1 ) being configured in the body (C) in such a way as to be movable and positionable between a first static configuration (C1), in which it is positioned at the distance (d1) from the lower stroke limit wall (12) of the first oscillating chamber (1), and a second static configuration (C2) in which it is positioned in an upper position, and is dynamically movable from one to another static configuration (C1), (C2), and maintained in one or the other static configuration (C1), (C2), according to which between the two pneumatic activating systems (P1 ) (P2) is connected to a compressed air source.

In particular: when the first pneumatic activating system (P1 ) is connected to the compressed air source (A1 ) and the second pneumatic activating system (P2) is not connected to the compressed air source (A2), the upper stroke limit wall (11) is pushed downwards and maintained in the first static configuration (C1 ) at the distance (d1 ) from the lower stroke limit wall (12), so as to define the upper stroke limit for the oscillation of the first oscillating piston (10) in the first oscillating chamber (1) (see in particular figures 2C, 2D, 2F, 2G); and when the first pneumatic activating system (P1) is not connected to the compressed air source (A1 ) and the second pneumatic activating system (P2) is connected to the compressed air source (A2), the upper wall (1 1 ) is pushed upwards with respect the lower stroke limit wall (12) of the first oscillating chamber (1 ) up to the second static configuration (C2), and maintained in this second static configuration (C2) so as to enable an upwards raising of the first oscillating piston (10) beyond the upper stroke limit thereof so as to enable the second pneumatic piston (20) to oscillate in the second oscillating chamber (2) up to reaching abutment against the upper stroke limit surface (21 ) of the second oscillating chamber (2), so that the cutting blade (L) can be made to oscillate vertically up to reaching the second upper cutting position (L2') for cutting a leather (V2) with a maximum thickness (m2) that is not greater than (d2) and greater than (d1) (in this regard figures 3C, 3D, 3F and 3G). Further and other advantageous characteristics and aspects of the cutting device (100) of the invention are set down in the following. In a preferred aspect, the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ) is configured and predisposed in the body (C) so that, when the first pneumatic activating system (P1 ) is not connected to the compressed air source (A1 ) and the second pneumatic activating system (P2) is connected to the compressed air source (A2), it can be movable upwards with respect to the body (C) up to a second static configuration (C2) in a position at a distance (d3) from the lower stroke limit wall (12) of the first oscillating chamber (1 ) that is greater than or equal to the distance (d2) between the lower stroke limit surface (22) and the upper stroke limit surface (21 ) of the second oscillating chamber (2) (see for example figures 3C and 3F).

In this way, when the second oscillating piston (20) is pneumatically activated to oscillate in the second oscillating chamber (2) between the lower stroke limit surface (22) and the upper stroke limit surface (21 ) of the second oscillating chamber (2), which are distanced from one another by a distance (d2) that is greater than distance (d1 ), the first oscillating piston (10) can be freely made to oscillate without abutting against the upper stroke limit wall (1 1 ) positioned in the second static configuration (C2), before the second oscillating piston (20) reaches the upper stroke limit in abutment against the upper stroke limit surface (21 ) of the second oscillating chamber (2). In a further preferred aspect, the first oscillating chamber (1 ) and the second oscillating chamber (2) are predisposed internally of the body (C) at a reciprocal distance from one another so that when the first oscillating piston (10) is in abutment against the lower stroke limit wall (12) of the first oscillating chamber (1 ), the second oscillating piston (20) is also in abutment against the lower stroke limit surface (22) of the second oscillating chamber (2), and vice versa, so as to have a single lower cutting position (L1 ) for the cutting blade (V), both when the first pneumatic activating system (P1 ) is connected to the compressed air source (A1 ) and when the second pneumatic activating system (P2) is connected to the compressed air source (A2). In a particularly preferred and advantageous aspect, the cutting device (100) of the invention is such as to comprise a manoeuvring chamber (4) predisposed inside the body (C), arranged in a position between the first oscillating chamber (1 ) and the second oscillating chamber (2), and having a lower abutment surface (42) and an upper abutment surface (41 ); a piston (40) predisposed in the manoeuvring chamber (4) between the lower abutment surface (42) and the upper abutment surface (41 ) and which is provided with a through-hole (43) for enabling free passage of the stem (14); an abutting element (44) having a lower abutment wall (45) predisposed so that the lower abutment wall (45) is arranged in the first oscillating chamber (1 ) so as to constitute the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ); a connecting element (46), internally hollow for the passage of the stem (14), which connects and solidly constrains the piston (40) to the abutting element (44) through a passage hole (28) present in the lower abutment surface (42) of the manoeuvring chamber (4).

The manoeuvring chamber (4) is such as to comprise: a first opening (4a), at or in proximity of the relative upper abutment surface (41 ), which is predisposed so as to be in communication with the first pneumatic activating system (P1 ) (see for example the figures 2C and 2F); and a second opening (4b), at or in proximity of the relative lower abutment surface (42), which in turn is predisposed so as to be in communication with the second pneumatic activating system (P2) (see for example figures 3C and 3 F).

In this way, owing to these special details, when the first pneumatic activating system (P1 ) is connected to the compressed air source (A1 ), and the compressed air source (A1 ) is activated to as to pneumatically activate the first oscillating piston (10) to oscillate in the first oscillating chamber (1 ), a compressed air flow can enter the manoeuvring chamber (4) through the first opening (4a) above the piston (40) so as to push the piston (40) downwards and maintain it against the lower abutment surface (42) of the manoeuvring chamber (4), and thus maintain, by means of the connecting element (46), the lower abutment wall (45) of the abutting element (44) positioned in the first static configuration (C1 ) at the distance (d1 ) from the lower stroke limit wall (12) of the first oscillating chamber (1 ), to constitute the upper stroke limit wall (1 1 ) for the first oscillating piston (10). Instead, when the second pneumatic activating system (P2) is connected to the compressed air source (A2), and the compressed air source (A2) is activated to pneumatically activate the second oscillating piston (20) to oscillate in the second oscillating chamber (2), a compressed air flow can enter the manoeuvring chamber (4) through the second opening (4b) below the piston (40) so as to push and raise the piston (40) upwards and against the upper abutment surface (41 ) of the manoeuvring chamber (4), and therefore raise the abutting element (44) upwards, by means of the connecting element (46), so that the relative lower abutment wall (45), which constitutes the upper stroke limit wall (11 ) of the first oscillating chamber (1 ), is raised and distanced from the lower stroke limit wall (12) of the first oscillating chamber (1 ) up to being positioned in the second static configuration (C2), for enabling an upward raising of the first oscillating piston (10) beyond the upper stroke limit thereof so as to enable the pneumatic piston (20) to oscillate in the second oscillating chamber (2) up to reaching abutment against the upper stroke limit surface (21 ) of the second oscillating chamber (2).

Further and other particularly preferred aspects of the cutting device (100) proposed by the invention, as illustrated in the accompanying figures of the drawings, are as follows. The body (C) is conformed so as to comprise a lower cylindrical portion (16) and an upper cylindrical portion (17), the first oscillating chamber (1 ) being contained in the lower cylindrical portion (16) and the second oscillating chamber (2) being contained in the upper cylindrical portion (17) and the stem (14), which bears the cutting blade (L), being predisposed so as to be alternatingly slidable with a first part (14a) thereof in the lower cylindrical portion (16) and a second part (14b) thereof in the upper cylindrical portion (17).

The first part (14a) of the stem (14) is conformed so as to exhibit: two annular portions (141 , 142) in sliding contact with the walls of the lower cylindrical portion (16), an annular recess (140) comprised between the two annular portions (141 , 142), and an internal conduit (143). The first part (14a) of the stem (14) further comprises through-holes (144) predisposed in a position below the annular recess (140) in order to place the outside of the second part (14a) of the stem (14) in communication with the internal conduit (143). The first oscillating piston (10) is. provided with through-holes (130) (visible for example in figures 3C and 3F) that are predisposed so as to place the internal conduit (143) of the first part (14a) of the stem (14) in communication with the second part (1 B) of the first oscillating chamber (10) comprised between the first oscillating piston (10) and the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ).

The first pneumatic activating system (P1 ) is designed and conformed so as to comprise: a switching chamber (8) predisposed in a portion of the internal walls of the lower cylindrical portion (16) facing the first part (14a) of the stem (14); a main conduit (81 ) predisposed in the body (C) and involving the lower cylindrical portion (16) so as to be connectable and in communication with the compressed air source (A1 ) and with a lower part of the switching chamber

(8), a secondary conduit (82) predisposed in the lower cylindrical portion (16) of the body (C) so as to be in communication with an upper part of the switching chamber (8) and with the first oscillating chamber (1 ) through a passage hole (83) in the lower stroke limit wall (12) of the first oscillating chamber (1 ); an upper discharge (S1 ), realised in the lower cylindrical portion (16) in a position above and in communication with the switching chamber (8) so as to be in communication with the outside; and a lower discharge (S2), realised in the lower cylindrical portion (16) in a position below the switching chamber (8) so as to be in communication with the outside.

The annular recess (140) of the first part (14a) of the stem (14) is realised and conformed so as to have dimensions such that, and with the through-holes (144) of the first part (14a) of the stem (14) being positioned with respect to the annular recess (140) such that, with the alternating sliding of the stem (14), and therefore of the first part (14a) of the stem (14) within the lower cylindrical portion (16), the following conditions and situations emerge: when the annular recess (140) of the first part (14a) of the stem (14) is positioned at the switching chamber (8) of the first pneumatic activating system (P1 ), the through-holes (144) of the first part (14a) of the stem (14) are positioned at the lower discharge (S2) of the first pneumatic activating system (P1 ), so that the main conduit (81 ) of the first pneumatic activating system (P1 ) is in communication via the annular recess (140) with the secondary conduit (82) and therefore the compressed air source (A1 ), when activated, is in communication with the first part (1A) of the first oscillating chamber (10) and the lower stroke limit wall (12), while the second part (1 B) of the first oscillating chamber (1 1 ), between first oscillating piston (10) and the upper stroke limit wall (1 1 ), is in communication with the lower discharge (S2) via the through-holes (130) of first oscillating piston (10), the internal conduit (143) and the through-holes (144) of the first part (14a) of the stem (14), so that the first oscillating piston (10) can be pneumatically pushed upwards (see figures 2C and 2D in this regard); and when the annular recess (140) of the first part (14a) of the stem (14) is positioned at both the upper discharge (S1 ) and the upper part of the switching chamber (8) communicating with the secondary conduit (82) of the first pneumatic activating system (P1 ), the through-holes (144) of the first part (14a) of the stem (14) are in the lower part of the switching chamber (8) and communicating with the main conduit (81 ) of the first pneumatic activating system (P1 ), so that the compressed air source (A1 ), when activated, is in communication, through the through-holes (144) and the internal conduit (143) of the first part (14a) of the stem (14), and the through-holes (130) present in the first oscillating piston (10), with the second part (1 B) of the first oscillating chamber (1 ) between the upper stroke limit wall (1 1 ) and the first oscillating piston (10), while the first part (1A) of the first oscillating chamber (1 ) between the first oscillating piston (10) and the lower stroke limit wall (12), is in communication with the upper discharge (S1 ) of the first pneumatic activating system (P1 ) through the secondary conduit (82), so that the first oscillating piston (10) can be pneumatically pushed downwards (see figures 2F and 2G in this regard).

Further, the first pneumatic activating system (P1 ) comprises a service conduit (84), branching from the main conduit (81 ) and opening into the first opening (4a) of the manoeuvring chamber (4).

In this way, when the first pneumatic activating system (P1 ) is connected to the compressed air source (A1 ), and this compressed air source (A1 ) is activated to oscillate the first oscillating piston (10) internally of the first oscillating chamber (1 ), a compressed air flow can enter the manoeuvring chamber through the service conduit (84) and the first opening (4a) and push the piston (40) downwards and maintain it against the lower abutment surface (42) of the manoeuvring chamber (4), and therefore push the abutting element (44) downwards, by means of the connecting element (46), so that the relative lower abutment wall (45), which constitutes the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ), can be maintained in the first static configuration (C1 ) at distance (d1 ) from the lower stroke limit wall (12) of first oscillating chamber (1 ), to define the upper stroke limit for the oscillation of the first oscillating piston (1 ).

In turn, the second part (14b) of the stem (14) is conformed so as to exhibit: two annular portions (151 , 152) in sliding contact with the walls of the upper cylindrical portion (17) and an annular recess (150) comprised between the two annular portions (151 , 152), and an internal conduit (153).

The second part (14b) of the stem (14) further comprises through-holes (154) predisposed in a position below the annular recess (150) in order to place the outside of the second part (14b) of the stem (14) in communication with the internal conduit (153).

The second oscillating piston (20) is provided with through-holes (160) (see for example figures 3D and 3G) which are predisposed so as to place the internal conduit (153) of the second part (14b) of the stem (14) in communication with the second part (2B) of the second oscillating chamber (20) comprised between the second oscillating piston (20) and the upper stroke limit surface (21 ) of the second oscillating chamber (2).

The second pneumatic activating system (P2) is designed and conformed so as to comprise: a switching chamber (9) predisposed in a portion of the internal walls of the upper cylindrical portion (17) facing the second part (14b) of the stem (14); a main conduit (91 ) predisposed in the body (C) and involving the upper cylindrical portion (17) so as to be connectable and in communication with the compressed air source (A2) and with a lower part of the switching chamber

(9); a secondary conduit (92) predisposed in the upper cylindrical portion (17) of the body (C) so as to be in communication with an upper part of the switching chamber (9) and with the second oscillating chamber (2) through a passage hole (93) in the lower stroke limit surface (22) of the second oscillating chamber (2); an upper discharge (S3), realised in the upper cylindrical portion (17) in a position above and in communication with the switching chamber (9) and so as to be in communication with the outside; and a lower discharge (S4) communicating with the outside realised in the upper cylindrical portion (17) in a position below the switching chamber (9) and so as to be in communication with the outside. The annular recess (150) of the second part (14b) of the stem (14) has dimensions such that, and with the through-holes (154) of the second part (14b) of the stem (14) being positioned with respect to the annular recess (150) such that, with the alternating sliding of the stem (14), and therefore of the second part (14b) of the stem (14) internally of the upper cylindrical portion (17) the following conditions and situations result: when the annular recess (150) of the second part (14b) of the stem (14) is positioned at the switching chamber (9) of the second pneumatic activating system (P2), the through-holes (154) of the second part (14b) of the stem are positioned at the lower discharge (S4) of the second pneumatic activating system (P2), so that the main conduit (91 ) of the second pneumatic activating system (P2) is in communication through the annular recess (150) with the secondary conduit (92) and therefore the compressed air source (A2), when activated, is in communication with the first part (2A) of the second oscillating chamber (2) between the second oscillating piston (20) and the lower stroke limit surface (22), while the second part (2B) of the second oscillating chamber (2) between the second oscillating piston (20) and the upper stroke limit surface (21 ) is in communication with the lower discharge (S4) of the second pneumatic activating system (P2) through the through-holes (160) of the second oscillating piston (20), the internal conduit (153) and the through-holes (154) of the second part (14b) of the stem (14), so that the second oscillating piston (20) can be pneumatically pushed upwards (in this regards see figures 3C and 3D); and when the annular recess (150) of the second part (14b) of the stem (14) is positioned at both the upper discharge (S3) and the upper part of the switching chamber (9) communicating with the secondary conduit (92) of the second pneumatic activating system (P2), the through-holes (154) of the second part (14b) of the stem (14) are in the lower part of the switching chamber (9) and communicating with the main conduit (91 ) of the second pneumatic activating system (P2), so that the compressed air source (A2) when activated, is in communication, through the through-holes (154) and the internal conduit (153) of the second part (14b) of the stem (14), and the through-holes (160) present in the second oscillating piston (20), with the second part (2B) of the second oscillating chamber (2) between the upper stroke limit surface (21 ) and the second oscillating piston (20), while the first part (2A) of the second oscillating chamber (2) between the second oscillating piston (20) and the lower stroke limit surface (22) is in communication with the upper discharge (S3) of the second pneumatic activating system (P2), via the secondary conduit (92), so that the second oscillating piston (20) can be pneumatically pushed downwards (in this regard see figures 3F and 3G).

The second pneumatic activating system (P2) comprises a service conduit (94), branching from the main conduit (91 ) and which is predisposed in such a way as to open into the second opening (4b) of the manoeuvring chamber (4).

In this way, when the second pneumatic activating system (P2) is connected to the compressed air source (A2), and this compressed air source (A2) is activated to oscillate the second oscillating piston internally of the second oscillating chamber (2), a compressed air flow can enter the manoeuvring chamber through the service conduit (94) and the second opening (4b) and push the piston (40) upwards and maintain it against the upper abutment surface (41) of the manoeuvring chamber (4), and therefore push the abutting element (44) upwards, by means of the connecting element (46), so that the relative lower abutment wall (45), which constitutes the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ), can be raised upwards and positioned in the second static configuration (C2), at a distance (d3) from the lower stroke limit wall (12) of the first oscillating chamber (1 ) that is greater than or equal to the distance (d2) between the lower stroke limit surface (22) and the upper stroke limit surface (21 ) of the second oscillating chamber (2), so as to enable the first oscillating piston (10) to be raised upwards beyond the upper oscillation stroke limit thereof, so as to enable the second pneumatic piston (20) to oscillate in the second oscillating chamber (2) up to reaching abutment against the upper stroke limit surface (21 ) of the second oscillating chamber (2).

In a possible embodiment, the first pneumatic activating system (P1 ) is connected to and in communication with a first compressed air source (A1 ) and the second pneumatic activating system (P2) is connected to and in communication with a second compressed air source (A2), the first compressed air source (A1 ) and the second compressed air source (A2) being predisposed to be activated alternatively and independently of one another. In a further possible embodiment, the first pneumatic activating system (P1 ) and the second pneumatic activating system (P2) can be connected to and in communication with a second compressed air source (A1 , A2) by means of a valve organ (not illustrated in the accompanying figures as of known type) predisposed and commandable so that the compressed air source (A1 , A2) can direct the compressed air flow alternatively to the first pneumatic activating system (P1 ) or to the second pneumatic activating system (P2).

In the accompanying figures of the drawings, the compressed air sources, in the first case, or the compressed air source, in the second case, have been schematically denoted only with references (A1 ) and (A2) and with relative arrows indicating the compressed air flow coming therefrom and destined to supply the first pneumatic activating system (P1 ) or the second pneumatic activating system (P2), according to the type and thickness of the leather sheet to be scored and cut. By way of example, in the following a description is made of a possible functioning cycle of the cutting device (100) according to the invention, for example in a case in which it is desired to carry out a cut of a first leather sheet (V1 ), having a first thickness (ml ) not greater than the distance (d1 ), i.e. the working dimensions of the first oscillating chamber (1 ) (see figure 1 A), starting for example from the situation illustrated in figures 2B, 2C and 2D, wherein the first pneumatic activating system (P1 ) is connected to a compressed air source (A1 ) while the second pneumatic activating system (P2) is not connected to any compressed air source, the first oscillating piston (10) being in contact with the lower stroke limit wall (12) of first oscillating chamber (1 ), i.e. with the cutting blade (L) which is in the lower cutting position (L1 ), with the second oscillating piston (20) in contact with the lower stroke limit surface (22) of the second oscillating chamber (2) and with the piston (40) which is in contact with the lower abutment surface (42) of the manoeuvring chamber (4), and therefore the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ) positioned in the first static configuration (d ) at distance (d1 ) from the lower stroke limit wall (12) of the first oscillating chamber (1 ). In this situation, the first part (14a) of the stem (14) is positioned with respect to the lower cylindrical portion (16) of the body (C) in a position such that the recess (140) of the first part (14a) of the stem (14) is positioned at the switching chamber (8) of the first pneumatic activating system (P1 ), thus placing the main conduit (81 ) in communication with the secondary conduit (82), while the holes (144) of the first part (14a) of the stem (14) are at the lower discharge (S2) of the first pneumatic activating system (P1 ).

Therefore the compressed air source (A1 ), by means of the main conduit (81 ), the switching chamber (8), the secondary conduit (82) of the first pneumatic activating system (P1 ), and the passage hole (83) present in the lower stroke limit surface (12) of the first oscillating chamber (1 ), is in communication with the first part (1A) of the first oscillating chamber (1 ) comprised between the second oscillating piston (10) and lower stroke limit wall (12) of the oscillating chamber (1 ), while the second part (1 B) of the second oscillating chamber (1 ) comprised between the first oscillating piston (10) and the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ), via the holes (130) present in the first oscillating piston (10), the internal conduit (143) and the holes (144) of the first part (14a) of the stem (14), is in communication with the lower discharge (S2). The compressed air flow coming from the compressed air source (A1 ) arrives therefore in the first part (1A) of the first oscillating chamber (1 ), below first oscillating piston (10), pushing it consequently upwards, since the second part (1 B) of the first oscillating chamber (1 ), above first oscillating piston (10), is connected with the lower discharge (S2) of the first pneumatic activating system (P1 ), and then with the outside.

The first oscillating piston (10) is pushed upwards, with a contextual sliding upwards of the stem (14) in the body (C) and an upwards displacement of the cutting blade (L).

At the same time, a part of the compressed air flow coming from the compressed air source (A1 ), via the service conduit (84) of the first pneumatic activating system (P1 ) and via the first opening (4a) present in the manoeuvring chamber (4), enters the manoeuvring chamber (4) above the piston (40), maintaining it in contact and in abutment against the lower abutment surface (42) of the manoeuvring chamber (4).

In this way, the piston (40), by means of the connecting element (46), maintains the lower abutment wall (45) of the abutting element (44) positioned in the first static configuration (C1 ) at distance (d1 ) from the lower stroke limit wall (12) of the first oscillating chamber (1 ), for constituting the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ) and constituting the upper stroke limit for oscillation of the first oscillating piston (10). When the first oscillating piston (10) reaches abutment against the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ) (see figures 2F, 2G), the cutting blade (L) reaches the first upper cutting position (L2) (see figure 1 B), while the sliding upwards of the first part (14a) of the stem (14) in the lower cylindrical portion (16) of the body (C) determines the following condition (see in particular figure 2G): the holes (144) of the first part (14a) of the stem (14) are at the lower part of the switching chamber (8) and therefore in communication with the main conduit (81 ) of the first pneumatic activating system (P1 ), the recess (140) of first part (14a) of the stem (14) is positioned both at the upper discharge (S1 ) and in the upper part of the switching chamber (8), and therefore in communication with the secondary conduit (82) of the first pneumatic activating system (P1 ).

In this situation, the main conduit (81 ), via the holes (144) and the internal conduit (143) of the first part (14a) of the stem (14) and the holes (130) of the second oscillating piston (10), is in communication with the second part ( B) of the first oscillating chamber (1 ) comprised between the first oscillating piston (10) and the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ), while the first part (1 A) of the first oscillating chamber (1 ) below the first oscillating piston (10), via the passage hole (83), present in the lower stroke limit wall (12) of the first oscillating chamber (1 ), and the secondary conduit (82) is in communication with the upper discharge (S1 ) of the first pneumatic activating system (P1 ).

Therefore the compressed air flow coming from the compressed air source (A1 ) arrives therefore in the second part (1 B) of the first oscillating chamber (1 ), below first oscillating piston (10), pushing it consequently downwards, since the first part (1A) of the first oscillating chamber (1 ), below the first oscillating piston (10), is connected with the upper discharge (S1 ) of the first pneumatic activating system (P1 ), and therefore with the outside.

The first oscillating piston (10) is pushed upwards, with a contextual sliding downwards of the stem (14) in the body (C) and a downwards displacement of the cutting blade (L), for returning into the preceding situation of figure 1A, i.e. into the lower cutting position (L1 ).

During the above-described oscillation of the first oscillating piston (10) in the first oscillating chamber (1 ), the part of compressed air flow entering the manoeuvring chamber (4) maintains the piston (40) always in abutment against the lower abutment surface (42) of the manoeuvring chamber (4), and therefore the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ) fixed and stationary in the first static configuration (C1 ) at the distance (d1 ) from the lower stroke limit wall (12) of the first oscillating chamber (1 ).

Again, during the oscillation of the first oscillating chamber (10) in the first oscillating chamber (1 ), the second oscillating piston (20) can oscillate freely in the second oscillating chamber (2), without constituting an impediment to the oscillation of the first oscillating piston (10), since the second oscillating chamber (2) has larger dimensions with respect to the first oscillating chamber (1 ), i.e. the relative upper and lower stroke limit surface (21 , 22) are distanced by a distance (d2) greater than the above-mentioned distance (d1 ).

The cycle described in the following is repeated as long as the first pneumatic activating system (P1 ) is connected to the compressed air source (A1 ), and this is maintained active, while the second pneumatic activating system (P2) is not connected to any compressed air source, thus determining the oscillation of the cutting blade (L) with a first entity of vertical oscillation, between the lower cutting position (L1 ) and the first upper cutting position (L2) (figures 1A and 1 B).

At a moment when in becomes necessary to carry out cutting and scoring operations on a second leather sheet (V2) having a greater thickness (m2), in particular a greater thickness (m2) than the above-mentioned distance (d1 ), it is sufficient to deactivate/interrupt the connection between the first pneumatic activating system (P1 ) and the compressed air source (A1 ), and instead connect the second pneumatic activating system (P2) with the compressed air source (A2) and activate the compressed air source (A2). In this case, the compressed air flow coming from the compressed air source (A2) will only supply the second pneumatic activating system (P2), and therefore a part of the compressed air flow, via the service conduit (94) and the second opening (4b) of the manoeuvring chamber (4), will enter the manoeuvring chamber (4) below the piston (4) so as to push and raise the piston (40) upwards and against the upper abutment surface (41 ) of the manoeuvring chamber (4), and therefore raise the abutting element (44) upwards by means of the connecting element (46) so that the relative lower abutment wall (45), which constitutes the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ), is raised and distanced from the lower stroke limit wall (12) of the first oscillating chamber (1 ) up to being positioned in the second static configuration (C2).

In this way, the compressed air flow supplying the second pneumatic activating system (P2) can activate the oscillation of the second oscillating piston (20) in the second oscillating chamber (2), since the first oscillating piston (10) can be freely raised beyond its upper oscillation stroke limit (when it is activated by the first pneumatic activating system P1 )), as it is not impeded by the presence of the upper stroke limit wall (1 1 ) which is positioned in the second static configuration (C2), at a distance (d3) from the lower stroke limit wall (12) of the first oscillating chamber (1 ) that is greater than or equal to the distance (d2) between the upper and lower stroke limit surfaces (1 1 , 12) of the second oscillating chamber (2) (see figures 3C and 3D). Therefore, in this case, the operating cycle is as follows, considering a start from the situation illustrated in figures 3B, 3C and 3D, in which the second pneumatic activating system (P2) is connected to a compressed air source (A2) while the first pneumatic activating system (P1 ), as mentioned, is not connected to any compressed air source, with the second oscillating piston (20) being in contact with the lower stroke limit surface (22) of the second oscillating chamber (2) (and also the first oscillating piston (10) being in contact with the lower stroke limit wall (12) of the first oscillating chamber (1 )), i.e. with the cutting blade (L) in the lower cutting position (L1 ) and with the piston (40) which is maintained pushed upwards and in contact with the upper abutment surface (42) of the manoeuvring chamber (4), so as to maintain the upper wall (1 1 ) of the first oscillating chamber (1 ) in the second above- mentioned static configuration (C2).

In this situation, the second part (14b) of the stem (14) is positioned with respect to the upper cylindrical portion (17) of the body (C) in a position such that the recess (150) of the second part (14b) of the stem (14) is positioned at the switching chamber (9) of the second pneumatic activating system (P2), thus placing the main conduit (91 ) in communication with the secondary conduit (92), while the holes (154) of the second part (14b) of the stem (14) are at the lower discharge (S4) of the second pneumatic activating system (P2).

Therefore the compressed air source (A2), by means of the main conduit (91 ), the switching chamber (9), the secondary conduit (92) of the second pneumatic activating system (P2), and the passage hole (93) present in the lower stroke limit surface (22) of the second oscillating chamber (2), is in communication with the first part (2A) of the second oscillating chamber (2) comprised between the second oscillating piston (20) and the lower stroke limit surface (22) of the second oscillating chamber (2), while the second part (2B) of the second oscillating chamber (2) comprised between the oscillating piston (20) and the upper stroke limit surface (21 ) of the second oscillating chamber (2), via the holes (160) present in the second oscillating piston (20), the internal conduit (153) and the holes (154) of the second part (14b) of the stem (14), is in communication with the lower discharge (S4) of the second pneumatic activating system (P2).

The compressed air flow coming from the compressed air source (A2) arrives in the first part (2A) of the second oscillating chamber (2), below the second oscillating piston (20), pushing it consequently upwards, since the second part (2B) of the second oscillating chamber (2), above the second oscillating piston (20), is connected with the lower discharge (S4) of the second pneumatic activating system (P2), and therefore with the outside.

The second oscillating piston (20) is therefore pushed upwards, with a contextual sliding upwards of the stem (14) in the body (C) and an upwards displacement of the cutting blade (L).

When the second oscillating piston (20) reaches abutment against the upper stroke limit surface (21 ) of the second oscillating chamber (2) (see figures 3F, 3G), the cutting blade (L) reaches the second upper cutting position (L2') (see figure 1 D) at a greater height from the work plane (PL) with respect to the previous first upper cutting position (L2) (when it was the first pneumatic activating system (P1 ) that was connected with the compressed air source), while the sliding upwards of the second part (14b) of the stem (14) in the upper cylindrical portion (17) of the body (C) determines the following condition (see in particular figure 3G): the holes (154) of the second part (14b) of the stem (14) are at the lower part of the switching chamber (9) and therefore in communication with the main conduit (91 ) of the second pneumatic activating system (P2), the recess (150) of the first part (14b) of the stem (14) is positioned both at the upper discharge (S3) and in the upper part of the switching chamber (9), and therefore in communication with the secondary conduit (92) of the second pneumatic activating system (P2).

In this situation, the main conduit (91 ), via the holes (154) and the internal conduit (153) of the second part (14b) of the stem (14) and the holes (160) of the second oscillating piston (20), is in communication with the second part (2B) of the second oscillating chamber (2), comprised between the second oscillating piston (20) and the upper stroke limit surface (21 ) of the second oscillating chamber (2), while the first part (2A) of the second oscillating chamber (2) below the second oscillating piston (20), via the passage hole (93), present in the lower stroke limit surface (22) of the second oscillating chamber (2), and the secondary conduit (92) is in communication with the upper discharge (S3) of the second pneumatic activating system (P2).

Therefore the compressed air flow coming from the compressed air source (A2) arrives in the second part (2B) of the second oscillating chamber (2), below the second oscillating piston (20), pushing it consequently downwards, since the first part (2A) of the second oscillating chamber (2), below the second oscillating piston (20), is connected with the upper discharge (S3) of the second pneumatic activating system (P2), and therefore with the outside.

The second oscillating piston (20) is therefore pushed downwards, with a contextual sliding downwards of the stem (14) in the body (C) and a downwards displacement of the cutting blade (L), for returning into the preceding situation of figure 1 C, i.e. in the lower cutting position (L1 ).

During the above-described oscillation of the second oscillating piston (20) in the second oscillating chamber (2), the part of compressed air flow entering the manoeuvring chamber (4) maintains the piston (40) always in abutment against the upper abutment surface (42) of the manoeuvring chamber (4), and therefore the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ) fixed and stationary in the second static configuration (C2) at the distance (d3) from the lower stroke limit wall (12) of the first oscillating chamber (1 ), enabling the first oscillating piston (10) to freely oscillate upwards with no constraint.

The cycle described in the following is repeated until the second pneumatic activating system (P2) is connected to the compressed air source (A2), and this is maintained active, thus determining the oscillation of the cutting blade (L) with a second entity of vertical oscillation, between the lower cutting position (L1 ) and the second upper cutting position (Ι_2') (figures 1A and 1 D), at a greater height from the work plane (PL) with respect to the first upper cutting position (L2) reachable when it is the first pneumatic activating system (P1 ) that is connected to the compressed air source.

The cutting device (100) of the invention has been described above, and illustrated in the accompanying figures, with the second oscillating chamber (2) arranged superiorly of the first oscillating chamber (1 ): in a different possible arrangement that is entirely equivalent and therefore falling within the scope of the invention as claimed, the second oscillating chamber (2) might also be arranged inferiorly of the first oscillating chamber (1 ). According to other possible equivalent arrangements, and therefore also falling within the scope of the invention as it is claimed, instead of the upper stroke limit wall (1 1 ) of the first oscillating chamber (1 ) (i.e. the smaller one) it might be the lower stroke limit wall (12) of the first oscillating chamber (1 ) that is predisposed and configured so as to be mobile and movable between two static configurations so as to be able to increase the distance from the upper stroke limit wall (1 1 ) when it is necessary to supply, with compressed air, the second pneumatic activating system (P2) in order to oscillate the second oscillating piston (20) in the second oscillating chamber (2) for cutting and scoring leather sheets having a greater thickness.