WO2022189984A1

WO2022189984A1 - A pneumatic cutting device having an oscillating blade for leather sheet cutting machines

Info

Publication number: WO2022189984A1
Application number: PCT/IB2022/052078
Authority: WO
Inventors: Gianni Gallucci
Original assignee: Teseo S.P.A.
Priority date: 2021-03-11
Filing date: 2022-03-09
Publication date: 2022-09-15
Also published as: IT202100005672A1; CN117255863A; EP4305213A1

Abstract

The cutting device (100) comprises: a body (C); a cutting blade (L); an oscillating chamber (1); an oscillating piston (10) in the oscillating chamber (1 ) and with the rod (14) connected to the cutting blade (L); a pneumatic activating system (P), for activating the oscillating piston (10) and therefore the cutting blade (L) in oscillation between a lower cutting position (L1) and an upper cutting position (L2); an auxiliary oscillating chamber (2), superiorly of the oscillating chamber (1); an auxiliary piston (23) in the auxiliary oscillating chamber (2). The body (C) comprises a first upper body (C1 ) and a second lower body (C2), the second lower body (C2) being axially translatable with respect to the first upper body (C1). The auxiliary oscillating chamber (2) is in the first upper body (C1) and communicating with the pneumatic activating system, the oscillating chamber (1) is in the second lower body (C2). The rod (25) of the auxiliary piston (23) is connected to the second lower body (C2). When the pneumatic activating system (P) is activated the auxiliary piston (23) pushes the second lower body (C2) downwards into a lowered position (TA). Elastic pushing means (3) act on the auxiliary piston (23) in such a way that, when the pneumatic activating system (P) is deactivated, the auxiliary piston (23) is pushed upwards and the second lower body (C2) is moved into a raised position (TS) in which the cutting blade (L) is raised into a raised non- operating position (LR).

Description

A PNEUMATIC CUTTING DEVICE HAVING AN OSCILLATING BLADE FOR LEATHER SHEET CUTTING MACHINES

FIELD OF THE INVENTION

The present invention relates to the particular technical sector concerning cutting machines for cutting sheet materials, such as skins, leather sheets, hides, synthetic leather sheets, etc.

In particular, the present invention relates to a pneumatic cutting device having an oscillating blade destined to be mounted on the cutting machines.

DESCRIPTION OF THE PRIOR ART Cutting machines comprise a frame, which is arranged positioned above a work plane, where the materials to be cut are laid out, such as for example skins (hides, leather sheets), synthetic skins and the like, and a cutting device inferiorly provided with a cutting blade.

The cutting machines further comprise movement means, which are borne by the frame and movable with respect thereto, so as to move and displace the cutting device according to the three Cartesian axes above the work plane so that the cutting blade can be positioned above the skins, be lowered to score the leather sheet and be moved according to a given cutting pathway so as to cut the skins on the basis of prefixed and/or desired profiles. The cutting devices used for this purpose are realised in such a way that the cutting blade can be made to oscillate vertically during the cutting of the leather sheets, from a lower cutting position to an upper cutting position, while always remaining within the thickness of the material to be scored/cut.

Cutting devices are known which are made in such a way as to be able to cause the cutting blade to oscillate vertically via an activation of a pneumatic type (for example compressed air). These cutting devices having a pneumatic activation are realised in such a way as to comprise a body, usually having a cylindrical shape, an oscillating chamber, internally of the body, having an upper end-run wall and a lower end-run wall, an oscillating piston, provided with a head and a rod, which is arranged in such a way that the head is arranged in the oscillating chamber and with the rod connected to the cutting blade.

Also provided is a pneumatic activating system communicating with the oscillating chamber to activate the piston head in oscillation inside the oscillating chamber between the upper end-run wall and the lower end-run wall, and, consequently, via the piston rod, to cause the cutting blade to oscillate vertically.

The pneumatic activating system comprises a pneumatic supply source, for example compressed air, a supply conduit, connected to the pneumatic supply source, and a discharge, in communication with the outside.

The supply conduit and the discharge are arranged internally of the body and are configured in such a way that the part of the oscillating chamber comprised between the piston head and the upper end-run wall, and the part of the oscillating chamber comprised between the piston head and the lower end-run wall, are respectively placed in communication alternatingly with the supply conduit and with the discharge so as to make the oscillation of the piston head possible inside the oscillating chamber.

In particular, when the pneumatic supply conduit is placed in communication with the part of the oscillating chamber comprised between the piston head and the upper end-run wall, the part of the oscillating chamber comprised between the piston head and the lower end-run wall is in communication with the discharge; in this case the piston is pneumatically pushed downwards; while when the supply conduit is placed in communication with the part of the oscillating chamber comprised between the piston head and the lower end-run wall, the part of the oscillating chamber comprised between the piston head and the upper end-run wall is in communication with the discharge, and in this case the piston is pneumatically pushed upwards, thus generating an oscillating motion inside the oscillating chamber and the vertical oscillation of the cutting blade.

In this specific sector of cutting leather sheets and like materials, such as leather, synthetic leather sheets, etc., it is often required, and is necessary, to carry out cutting of shapes having a profile that is very jagged or interrupted, with corners or changes of direction, even of a radical nature: in these cases it is necessary to carry out a change in direction of movement of the cutting blade.

In order to perform this operation, i.e. a change in direction of movement of the cutting blade, the cutting blade must first be extracted and disengaged from the material, in order then to be rotated into the new cutting direction, and lastly lowered so as to penetrate into the material and newly made to oscillate in order to carry out the scoring and cutting.

In the types of pneumatic cutting devices described in the foregoing, the disengagement and extraction of the cutting blade from the material is carried out by raising the whole cutting device. This operation requires a certain amount of time, to the detriment of productivity. Further, the weight of the cutting device can also be a number of kilograms, with a not-insignificant inertia in relation to the short distances involved (in the order of millimetres).

This practice doubtless constitutes a drawback and an issue, particularly in all those cases in which the shapes to be cut have especially complicated and jagged profiles such as to require the raising of the cutting device various tens of times in order to complete the cutting operations.

Document EP 3 374 528, in the name of the same Applicant, describes a novel pneumatic cutting device with oscillating blade having the purpose of obviating the above-described drawbacks and able to extract the cutting blade from the material without having to resort to the raising of the whole device.

The pneumatic cutting device described in the above-cited document is provided with a body comprises: an oscillating chamber, internally of the body, an oscillating piston, having a head, arranged in the oscillating chamber, and a rod connected to the cutting blade, and a pneumatic activating system, comprising a supply conduit and at least a discharge which are configured and arranged to activate the piston head in oscillation inside the oscillating chamber, and thus activate the rod and thus also the cutting blade in oscillation.

It further comprises an auxiliary oscillating chamber, which is arranged superiorly of the oscillating chamber of the oscillating piston connected to the cutting blade, and an auxiliary piston which is provided with a relative head and a relative rod. The auxiliary oscillating chamber is in communication with the pneumatic supply source while the auxiliary piston is predisposed in such a way that the relative head is situated internally of the auxiliary oscillating chamber while the relative rod is connected to the oscillating piston head via a hole present in the upper end-run wall of the oscillating chamber.

The auxiliary oscillating chamber and the auxiliary piston rod are dimensioned in such a way that, when the pneumatic activating system is active to activate the oscillating piston inside the oscillating chamber, the auxiliary piston head is activated inside the auxiliary chamber (as the auxiliary piston rod is connected to the oscillating piston head) until reaching at most an upper end-run position which remains distant from and below the upper wall of the auxiliary oscillating chamber. In other words, when the oscillating piston head is activated pneumatically to oscillate inside the oscillating chamber, to activate the cutting blade in oscillation, the auxiliary piston is also activated in vertical oscillation as the relative rod is connected to the oscillating piston head, and the auxiliary piston head is activated inside the auxiliary oscillating chamber without ever going into abutment against the upper wall of the auxiliary oscillating chamber.

In the cutting device described in the above-mentioned document, a pusher element is present, which is arranged in the auxiliary oscillating chamber, below the auxiliary piston head, and which is activatable, following the deactivation of the pneumatic supply source, to push the auxiliary piston head upwards, and thus raise the auxiliary piston until the relative head thereof is in abutment against the upper wall of the auxiliary oscillating chamber. The raising of the auxiliary piston determines the contextual raising of the oscillating piston (as the auxiliary piston rod is connected to the oscillating piston head) and thus the raising of the cutting blade above the upper cutting position, and therefore the extraction thereof from the material to be cut, by positioning the blade in a raised position with respect to the material. For this purpose, in order to allow the raising of the oscillating piston head, the upper end-run wall of the oscillating chamber is configured and predisposed in such a way as to be moved upwards in order to allow a raising of the oscillating piston until the auxiliary piston reaches with the relative head thereof in abutment against the upper wall of the auxiliary oscillating chamber. The cutting device has been demonstrated to be effective in raising and extracting the cutting blade in a raised position with respect to the material to be cut without having recourse to the raising of the whole device.

Notwithstanding this, however, the Applicant has found how, for such a cutting device, it is not always possible to attain high cutting speeds, as for the oscillation of the cutting blade, with respect to the other pneumatic cutting devices of the prior art, it is necessary also to activate in oscillation the auxiliary piston, and therefor move a greater mass.

This, in some circumstances, can limit the maximum reachable oscillation speed, can require an overall longer time to complete the cutting operations on a given material, and thus have a negative effect on productivity.

SUMMARY OF THE INVENTION

The aim of the present invention is therefore to describe a pneumatic cutting device having an oscillating blade for leather sheet cutting machines, able to obviate the above-mentioned drawbacks. In particular, the aim of the present invention is to describe a novel pneumatic cutting device having an oscillating blade, able to extract and disengage the cutting blade from the material, without having to be raised with respect to the work plane, and at the same time to be able to reach extremely high oscillation velocities of the cutting blade. The above-cited aims are attained with a pneumatic cutting device having an oscillating blade for leather sheet cutting machines according to the contents of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristics of the pneumatic cutting device having an oscillating blade for leather sheet cutting machines of the invention are described in the following with reference to the accompanying tables of drawings, in which:

- figures 1A and 1B illustrate the pneumatic cutting device with an oscillating blade for leather sheet cutting machines, object of the invention, in two distinct operating configurations of the oscillating cutting blade during activation in oscillation thereof for cutting a leather sheet, where figure 1A illustrates the lower cutting position reachable by the cutting blade during oscillation thereof, while figure 1 B illustrates the upper cutting position reachable by the cutting blade during oscillation thereof;

- figure 1C illustrates the pneumatic cutting device having an oscillating blade of the invention in a particular non-operating configuration in which it the cutting blade can be brought i.e. into a raised position, lifted with respect to the leather sheet, and then extracted and disengaged from the leather sheet without this leading to the raising of the whole device; where figure 2A illustrates the pneumatic cutting device having an oscillating blade of the invention, represented with the relative cutting blade in the operating configuration of figure 1A, i.e. in the lower cutting position reachable by the blade during oscillation thereof;

- figure 2B is a view along section plane ll-ll of figure 2A;

- figure 2C illustrates detail K of figure 2B in larger scale;

- figure 3A illustrates the pneumatic cutting device of figure 2A represented with the relative cutting blade in the operating configuration of figure 1B, i.e. in the upper cutting position reachable by the blade during oscillation thereof;

- figure 3B is a view along section plane Ill-Ill of figure 3A;

-figure 3C illustrates detail H of figure 3B in larger scale;

- figure 4A illustrates the pneumatic cutting device of figure 2A, represented with the relative cutting blade in the operating configuration of figure 1 C, that is with the cutting blade in the non-operating configuration i.e. in a raised position with respect to the leather sheet, thus extracted and disengaged from the leather sheet;

- figure 4B is a view along section plane IV-IV of figure 4A;

- figure 4C illustrates detail J of figure 4B in larger scale.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

The cutting device (100) is realised in such a way as to comprise: a body (C); a cutting blade (L) for cutting a leather sheet (V) stretched on a work plane; an oscillating chamber (1), internal of the body (C), comprising an upper end-run wall (11 ) and a lower end-run wall (12); an oscillating piston (10), having a head (13) and a rod (14), the oscillating piston (10) being predisposed with the head (13) thereof inserted in the oscillating chamber (1 ), between the upper end-run wall (11) and the lower end-run wall (12), the rod (14) being connected to the cutting blade (L); a pneumatic activating system (P), comprising a pneumatic supply source (P1) and at least a discharge (S1, S2), to pneumatically activate the head (13) of the oscillating piston (10) to oscillate inside the oscillating chamber (1) between the lower end-run wall (12) and the upper end-run wall (11), and therefore cause the oscillating piston (10) and the cutting blade (L) to oscillate vertically between a lower cutting position (L1) of the leather sheet (V) and an upper cutting position (L2) of the leather sheet (V) (see for example figures 1 A, 1 B, 2A, 3A). The cutting device (100) is realised in such a way as also to comprise (see for example figures 2B, 3B, 4B): an auxiliary oscillating chamber (2), which is arranged internally of the body (C), superiorly of the oscillating chamber (1), and having an upper abutment surface (21 ) and a lower abutment surface (22); an auxiliary piston (23) having a head (24) and a rod (25), the auxiliary piston (23) being arranged so that the relative head (24) is situated internally of the auxiliary oscillating chamber (2).

The special characteristics of the cutting device (100) of the present invention consist in the fact that: the body (C) is realised in such a way as to comprise a first upper body (C1 ) and a second lower body (C2), the second lower body (C2) being arranged in such a way as to be able to translate axially with respect to the body (C) and therefore with respect to the first upper body (C1 ); the auxiliary oscillating chamber (2) is made in the first upper body (C1) with an upper part of the auxiliary oscillating chamber (2), being comprised between the upper abutment surface (21) and the head (24) of the auxiliary piston (23), which is in communication with the pneumatic supply source (P1); the oscillating chamber (1) is made in the second lower body (C2), the rod (14) of the oscillating piston (10) being arranged so as to be slidable alternatingly in a passage channel (150) present in the second lower body (C2) which enables connection with the cutting blade (L).

The pneumatic activating system (P) is arranged and configured in such a way that, when the pneumatic activating system (P) is activated, a first part (1A) of the oscillating chamber (1), comprised between the head (13) of the oscillating piston (10) and the lower end-run wall (12), and a second part (1B) of the oscillating chamber (1), comprised between the head (13) of the oscillating piston (10) and the upper end-run wall (11), are placed in communication alternatively with the pneumatic supply source (P1) and with the at least a discharge (S1, S2), to pneumatically activate the head (13) of the oscillating piston (10) to oscillate inside the oscillating chamber (1) between the lower end-run wall (12) and the upper end-run wall (11), and therefore cause the rod (14) and consequently the cutting blade (L) to oscillate vertically between the lower cutting position (L1) and the upper cutting position (L2). Further, the first upper body (C1) comprises a sliding channel (CS), communicating with the auxiliary oscillating chamber (2) via the lower abutment surface (22) and with the rod (25) of the auxiliary piston (23) which is arranged slidably in the sliding channel (CS) and connected, at a lower end, to the second lower body (C2). The cutting device (100) further comprises elastic pushing means (3), arranged and configured in such a way as to act on the head (24) of the auxiliary piston (23) to exert on the head (24) of the auxiliary piston (23) a push towards the upper abutment surface (21) of the auxiliary oscillating chamber (2) in such a way that, with the pneumatic activating system (P) not operating, the auxiliary piston (23) is maintained in a raised position (PS) and thus maintain, by means of the respective rod (25), the second lower body (C2) in a raised position (TS) with respect to the body (C) in which the cutting blade (L) is in a raised non-operating position (LR) (see in particular figures 4B and 4C).

In this way, owing to the special characteristics as described in the foregoing, with the cutting device (100) of the invention it is possible to carry out the following operations.

When the pneumatic activating system (P) is activated, the pneumatic supply source (P1) is in communication with the upper part of the auxiliary oscillating chamber (2) and with the oscillating chamber (1 ) of the oscillating piston (10). In this way, the head (24) of the auxiliary piston (23) is pushed downwards, compressing and loading the elastic pushing means (3), into abutment against the lower abutment surface (22) of the auxiliary oscillating chamber (2) and thus the rod (25) of the auxiliary piston (23) pushes downwards and positions the second lower body (C2) in a lowered position (TA) with respect to the body (C) in which the cutting blade (L) can contact and penetrate into the leather sheet to be cut (see figures 2B, 2C).

At the same time, the head (13) of the oscillating piston (10) is activated to oscillate inside the oscillating chamber (1), between the lower end-run wall (12) and the upper end-run wall (11), so as to activate the cutting blade (L) in oscillation between the lower cutting position (L1) (figures 2A, 2B, 2C) and the upper cutting position (L2) (figures 3A, 3B, 3C) in order to carry out the cutting operations on the leather sheet to be cut.

Therefore, as long as the pneumatic activating system (P) is kept activated, the second lower body (C2) can be maintained in the relative lowered position (TA), enabling the cutting blade (L) to carry out the cutting operations on the leather sheet, as it is activated in oscillation from the lower cutting position (L1) to the upper cutting position (L2) by means of the oscillation of the oscillating piston (10). As soon as the pneumatic activating system (P), and therefore the pneumatic supply source (P1), are deactivated, the auxiliary oscillating chamber (2) will no longer be in communication with the pneumatic supply source (P1) (as well as the oscillating chamber (1)), and therefore the elastic pushing means (3) can push and displace the head (24) of the auxiliary piston (23) upwards, in order to return it into the raised position (PS) internally of the auxiliary oscillating chamber (2) (see figures 4B, 4C). The raising upwards of the rod (25) of the auxiliary piston (23) also determines the raising upwards of the second lower body (C2), and of the oscillating chamber (1) and of the oscillating piston (10) internally thereof, which is then returned into the respective raised position with respect to the body (C), in such a way that the cutting blade (L), which is connected to the oscillating piston (10), can be raised and returned into the raised non-operating position (LR) above the upper cutting position (L2) thereof beyond the thickness of the leather sheet (V) and thus be extracted and disengaged completely from the leather sheet (V) (see figures 4A, 4B, AC).

Therefore, owing to these special aspects (the oscillating chamber and the oscillating piston are internally of the second lower body which, as a function of the deactivation/activation of the pneumatic activating system can be translated with respect to the first upper body between a raised position and a lowered position), the cutting device (100) for the invention is such that, in an entirely immediate way, contextual to the deactivation of the pneumatic supply source (P1), the cutting blade (L) can be raised into a raised position (LR) above the upper cutting position (L2) thereof beyond the thickness of the leather sheet (V), and thus be extracted and disengaged completely from the leather sheet (V), all without having to require any movement or raising of the whole cutting device.

Further, once the second lower body is positioned, following the activation of the pneumatic activating system, in the lowered position, the oscillation of the cutting blade between the lower cutting position and the upper cutting position is delegated only to the oscillation of the oscillating piston, and thus independently of the auxiliary piston, which instead remains stationary in the auxiliary oscillating chamber, enabling reaching high oscillation speeds during the cutting steps, and therefore a greater productivity.

Therefore, the cutting device (100) according to the invention has effectively obviated the drawbacks in the cutting devices of the prior art cited in the foregoing. Other further advantageous characteristics and preferred aspects of the cutting device (100) of the invention are described in the following. The cutting device (100), in a first aspect, can be realised in such a way that the elastic pushing means (3) are arranged and configured in such a way as to act on the head (24) of the auxiliary piston (23) so as to exert on the head (24) of the auxiliary piston (23) a push towards the upper abutment surface (21) of the auxiliary oscillating chamber (2) in such a way that, with the pneumatic activating system (P) not operating, the auxiliary piston (23) is maintained in the raised position (PS) inside the auxiliary oscillating chamber (2) in which, with the respective head (24) thereof, it is in abutment against the upper abutment surface (21 ) of the auxiliary oscillating chamber (2).

The abutting of the head (24) of the auxiliary piston (23) against the upper abutment surface (21) of the auxiliary oscillating chamber (2) thus determines the raised position for the second lower body (C2) and therefore the height at which the cutting blade (L) is raised into the raised position (LR) in order to extract it from the leather sheet.

In a further aspect, the cutting device (100) can be realised in such a way that the first upper body (C1), the second lower body (C2) and the rod (25) of the auxiliary piston (23) are dimensioned and reciprocally arranged in such a way that, with the pneumatic activating system (P) not operating and with the elastic pushing means (3) maintaining the auxiliary piston (23) in the raised position (PS) inside the auxiliary oscillating chamber (2), the second lower body (C2) is in the raised position (TS) in abutment and pressed against the first upper body (C1).

The abutment of the second lower body (C2) against the first upper body (C1 ) can, or may not, coincide with the abutment of the head (24) of the auxiliary piston (23) against the upper abutment surface (21 ) of the auxiliary oscillating chamber (2).

A further preferred aspect of the cutting device (100) consists in the fact that the body (C) comprises an outer jacket (CA), with the first upper body (C1) being fixedly mounted internally of the outer jacket (CA) and the second lower body (C2) being mounted internally of the outer jacket (CA) slidably by means of at least a respective sliding guide (GA).

The sliding guide (GA) can comprise a vertical slot in the outer jacket which has a protuberance externally of the second lower body.

The outer jacket (CA), the first upper body (C1) and the second lower body (C2) preferably have a cylindrical shape.

For the purpose of activation in oscillation of the oscillating piston (10) internally of the oscillating chamber (1), and of the push downwards of the auxiliary piston (23) inside the auxiliary oscillating chamber (2), according to the preferred embodiment illustrated in the figures, the cutting device (100) has the following further characteristics.

The rod (14) of the oscillating piston (10) is conformed in such a way as to have: two annular portions (141, 142) in sliding contact with the walls of the passage channel (150) of the second lower body (C2); an annular recess (140), comprised between the two annular portions (141, 142); an internal conduit (17); and is provided with through-holes (18) which are arranged in a position below the annular recess (140) to place the outside of the rod (14) in communication with the internal conduit (17).

The head (13) of the oscillating piston (10) is provided with at least a through-hole (130) to place the internal conduit (17) of the rod (14) in communication with the second part (1B) of the oscillating chamber (1) comprised between the head (13) of the oscillating piston (10) and the upper end-run wall (11) of the oscillating chamber (1).

In turn, the pneumatic activating system (P) is made and configured in such a way as to comprise (see in particular figures (2B, 2C, 3B, 3C, 4B, 4C): a main supply conduit (7), which is arranged in the body (C) in such a way as to be in communication with the pneumatic supply source (P1) and with the upper part of the auxiliary oscillating chamber (2) via a hole (70) present in the upper abutment surface (21 ) of the auxiliary oscillating chamber (2); a first auxiliary supply conduit (71), realised internally of the rod (25) of the auxiliary piston (23) and communicating with the part of the auxiliary oscillating chamber (2) above the head (24) of the auxiliary piston (23) via a service hole (72) realised in the head (24) of the auxiliary piston (23); a switching chamber (8) in a portion of the walls of the passage conduit (150) present in the second lower body (C2); a second auxiliary supply conduit (73), which is arranged in the second lower body (C2) so as to be in communication with the first auxiliary supply conduit (71) and with a lower part (81 ) of the switching chamber (8); a third auxiliary supply conduit (74), which is arranged in the second lower body (C2) so as to be in communication with an upper part (82) of the switching chamber (8) and with the oscillating chamber (1) via a passage hole (83) in the lower end-run wall (12) of the oscillating chamber (1 ).

The pneumatic activating system (P) further comprises: an upper discharge (S1) communicating with outside realised in the second lower body (C2) in a position above the switching chamber (8), and a lower discharge (S2) communicating with the outside made in the second lower body (C2) in a position below the switching chamber (8).

Further, the annular recess (140) of the rod (14) has dimensions so that, and with the holes (18) of the rod (14) being positioned with respect to the annular recess (140) in such a way that, with the activation of the pneumatic supply source (P1) and the activation in oscillation of the oscillating piston (10) and the alternating sliding of the rod (14) of the oscillating piston (10) in the passage channel (150) of the second lower body (C2), the following conditions ensue.

When the annular recess (140) of the rod (14) is positioned at the switching chamber (8), the holes (18) of the rod (14) are positioned at the lower discharge (S2) (see figures 2B and 2C), so that the second auxiliary supply conduit (73) is in communication, via the annular recess (140), with the third auxiliary supply conduit (74) and therefore the pneumatic supply source (P1) is in communication with the first part (1A) of the oscillating chamber (1) between the head (13) of the oscillating piston (10) and the lower end-run wall (12), while the second part (1B) of the oscillating chamber (1) between the head (13) of the oscillating piston (10) and the upper end-run wall (11) is in communication with the lower discharge (S2) via the at least a through-hole (130) of the head (13) of the piston (10), the internal conduit (17) of the rod (14) and the holes (18) of the rod (14), so that the oscillating piston (10) can be pneumatically pushed upwards.

When the annular recess (140) of the rod (14) is positioned at both the upper discharge (S1) and the upper part (82) of the switching chamber (8) communicating with the third auxiliary supply conduit (74), the holes (18) of the rod (14) are at the lower part (81) of the switching chamber (8) and are in communication with the second auxiliary supply conduit (73) (see figures 3B and 3C), so that the pneumatic supply source (P1), via the holes (18) of the rod (14), the internal conduit (17) of the rod (14) and the at least a through-hole (130) present in the head (13) of the oscillating piston (10) is in communication with the second part (1B) of the oscillating chamber (1) between the upper end-run wall (11) and the head (13) of the oscillating piston (10), while the first part (1A) of the oscillating chamber (1) between the head (13) of the oscillating piston (10) and the lower end-run wall (12) is in communication with the upper discharge (S1) via the passage hole (83) and the third auxiliary supply conduit (74), so that the oscillating piston (10) can be pneumatically pushed downwards.

By way of example the following describes a possible functioning cycle of the cutting device (100) according to the invention, starting for example from the situation illustrated in figures 4A, 4B, and 4C, wherein the pneumatic activating system (P) and the pneumatic supply source (P1 ) are deactivated.

The elastic pushing means (3) keep the auxiliary piston (23) in the raised position (PS) internally of the auxiliary oscillating chamber (2), for example with the head (24) in abutment against the upper abutment surface (21) of the auxiliary oscillating chamber (2). Thus, the second lower body (C2) is maintained in the relative raised position (TS), and therefore also the oscillating piston (10) is raised, positioning the cutting blade (L) in the raised position (LR).

The head (13) of the oscillating piston (10), by force of gravity, will be positioned in abutment against the lower end-run wall (12) of the oscillating chamber (1).

In this situation, the rod (14) of the oscillating piston (10), is located, with respect to the passage channel (150) of the second lower body (C2), in a position such that the recess (140) of the rod (14) is positioned at the switching chamber (8), thus placing the main supply conduit (7), the first auxiliary supply conduit (71) and the second auxiliary supply conduit (72) in communication with the third auxiliary supply conduit (73), while the holes (18) of the rod (14) are positioned at the lower discharge (S2).

Therefore, by activating the pneumatic activating system (P), the pneumatic supply source (P1), via the main supply conduit (7) and the hole (70) present in the upper abutment surface (21) of the auxiliary oscillating chamber (2) is placed in communication with the upper part of the auxiliary oscillating chamber (2) and thus the pneumatic flow which enters the auxiliary oscillating chamber (2) and acts on the head (24) of the auxiliary piston (23), pushing it downwards up to placing it in abutment against the lower abutment surface (22) of the auxiliary oscillating chamber (2), compressing the elastic pushing means (3), and pushing the second lower body (C2) downwards and positioning it in the relative lowered position (TA) (see figures 2B and 2C).

The downwards displacement of the second lower body (C2) also brings about the lowering of the oscillating piston (10), which remains with the relative head (13) thereof in abutment against the lower end-run wall (12) of the oscillating chamber (1), and therefore of the cutting blade (L), and when the second lower body (C2) is in the lowered position (TA) the cutting blade (L) is in contact with the leather sheet (V) to be cut and in the relative lower cutting position (L1).

At the same time, the pneumatic supply source (P1), via the service hole (72) present in the head (24) of the auxiliary piston (23), the first auxiliary supply conduit (71) internally of the rod (25) of the auxiliary piston (23), the second auxiliary supply conduit (72), the switching chamber (8), the third auxiliary supply conduit (73) and the passage hole (83), is in communication with the first part (1A) of the oscillating chamber (1) comprised between the head (13) of the oscillating piston (10) and the lower end-run wall (12) of the oscillating chamber (1 ), while the second part (1B) of the oscillating chamber (1) comprised between the head (13) of the oscillating piston (10) and the upper end-run wall (11) of the oscillating chamber (1), via the through-hole (130) of the head (13), the internal conduit (17) of the rod (14) and the holes (18) of the rod (14) itself, is in communication with the lower discharge (S2) (as illustrated in figures 2B, 2C). Therefore, the pneumatic flow coming from the pneumatic supply source (P1 ) thus arrives in the first part (1A) of the oscillating chamber (1), below the head (13) of the oscillating piston (10), pushing it consequently upwards, as the second part (1B) of the oscillating chamber (1), above the head (13) of the oscillating piston (10), is connected to the lower discharge (S2). The oscillating piston (10) is thus pushed upwards, with a contemporaneous upwards sliding of the stem (14) thereof in the passage channel (150) and an upwards displacement of the cutting blade (L).

When the head (13) of the oscillating piston (10) reaches abutment against the upper end-run wall (11) of the oscillating chamber (1) (see figures 3B, 3C), the cutting blade (L) reaches the upper cutting position thereof (L2), while the sliding upwards of the rod (14) in the passage channel (150) of the second lower body (C2) determines the following condition (see in particular figure 3C).

The holes (18) of the rod (14) are at the lower part (82) of the switching chamber (8) and therefore communicating with the second auxiliary supply conduit (73), while the annular recess (140) of the rod (14) is positioned at both the upper discharge (S1) and the upper part (81) of the switching chamber (8) thus communicating with the third auxiliary supply conduit (74).

In this situation, the second auxiliary supply conduit (73), via the through-holes (18) of the rod (14), the internal conduit (17) of the rod (14) and the through-hole (130) present in the head (13) of the oscillating piston (10), is in communication with the second part (1B) of the oscillating chamber (1) included between the head (13) of the oscillating piston (10) and the upper end-run wall (11) of the oscillating chamber (1), while the first part (1A) of the oscillating chamber (1) below the head (13) of the oscillating piston (10) is in communication, via the passage hole (83) and the third auxiliary supply conduit (74), with the upper discharge (S1 ).

Therefore, the pneumatic flow coming from the pneumatic supply source (P1) reaches the second part (1B) of the oscillating chamber (1), above the head (13) of the oscillating piston (10), consequently pushing it downwards, as the first part (1A) of the oscillating chamber (1), beneath the head (13) of the oscillating piston (10), is connected to the upper discharge (S1): the oscillating piston (10) is thus pushed downwards, with a contemporaneous downwards sliding of the stem (14) thereof in the passage channel (150) of the second lower body (C2) and a downwards displacement of the cutting blade (L), in order to return into the preceding situation shown in figure 2C, i.e. into the lower cutting position (L1) thereof. The above-described cycle is repeated as long as the pneumatic supply source (P1) is active, thus causing the oscillation of the cutting blade (L) between the lower cutting position (L1) and the upper cutting position (L2) thereof, in order to carry out the cutting operations on the leather sheet (V). In this situation, the second lower body (C2) can be maintained in the relative lowered position (TA) as the pneumatic flow of the pneumatic supply source (P1) continues to act on the head (24) of the auxiliary piston (23) maintaining it in abutment against the lower abutment surface (22) of the auxiliary oscillating chamber (2). At the moment when there is a need to change the cutting direction, and therefore to have to disengage and completely extract the cutting blade (L) from the leather sheet (V), it will be sufficient to deactivate the pneumatic supply source (P1).

As soon as the pneumatic supply source (P1) is deactivated, the elastic pushing means (3), no longer compressed by the pneumatic action on the head (24) of the auxiliary piston (23), will push upwards and raise the auxiliary piston (23), thus also determining the raising of the second lower body (C2) into the raised position (TS).

The raising of the second lower body (C2) will also bring about the raising of the oscillating piston (10) as well as the raising of the cutting blade (L) into the raised position (LR), disengaging and extracting it from the leather sheet (V) (as illustrated in figures 4B and 4C).

Other further preferred aspects of the cutting device (100) of the invention are as follow.

The pneumatic activating system (P) comprises at least a first discharge conduit (91), which is made in the second lower body (C2) so as to be in communication with the lower discharge (S2) and the upper discharge (S1), and with the outside. The pneumatic activating system (P) comprises a second discharge conduit (92) which is made in the first upper body (C1) and is in communication with the outside, with the first discharge conduit (91) and the second discharge conduit (92) being arranged in such a way as to be mutually in communication.

In particular, when the pneumatic activating system (P) is activated, and the pneumatic supply source (P1) is in communication with the upper part of the auxiliary oscillating chamber (2), to push and position the second lower body (C2) in the lowered position (TA) with respect to the body (C), internally of the body (C), between the first upper body (C1) and the second lower body (C2) via which chamber (95) the first discharge conduit (91) is in communication with the second discharge conduit (92).

Further, when the pneumatic activating system (P) is deactivated, and the elastic pushing means (3) push the head (24) of the auxiliary piston (23) upwards in order to position the auxiliary piston (23) into the raised position (PS) inside the auxiliary oscillating chamber (2), and the second lower body (C2) is in the respective raised position (TS) with respect to the body (C), the first discharge conduit (91) is directly facing and in communication with the second discharge conduit (92).

The lower part of the auxiliary oscillating chamber (2) is advantageously in communication with the outside via a service conduit (98).

The service conduit (98) can be connected to and in communication with the second discharge conduit (92) realised in the first upper body (C1).

The elastic pushing means (3) comprise a compression spring (30) arranged coaxially to the rod (25) of the auxiliary piston (23) the sliding channel (CS) being made in such a way as to comprise an annular chamber (31 ) for the positioning of the compression spring (30).

The elastic pushing means (3) can also be made using other components equivalent to a compression spring.

Claims

1) A pneumatic cutting device (100) having an oscillating blade for leather sheet cutting machines, comprising: a body (C); a cutting blade (L) for cutting a leather sheet (V) stretched on a work plane; an oscillating chamber (1), internal of the body (C), comprising an upper end-run wall (11 ) and a lower end-run wall (12); an oscillating piston (10), having a head (13) and a rod (14), the oscillating piston (10) being predisposed with the head (13) thereof inserted in the oscillating chamber (1), between the upper end-run wall (11) and the lower end-run wall (12), the rod (14) being connected to the cutting blade (L); a pneumatic activating system (P), comprising a pneumatic supply source (P1) and at least a discharge (S1, S2), to pneumatically activate the head (13) of the oscillating piston (10) to oscillate inside the oscillating chamber (1) between the lower end-run wall (12) and the upper end-run wall (11), and therefore cause the cutting blade (L) to oscillate vertically between a lower cutting position (L1) of the leather sheet (V) and an upper cutting position (L2) of the leather sheet (V), an auxiliary oscillating chamber (2), arranged superiorly of the oscillating chamber (1), and having an upper abutment surface (21) and a lower abutment surface (22); an auxiliary piston (23) having a head (24) and a rod (25), the auxiliary piston (23) being arranged so that the respective head (24) is situated internally of the auxiliary oscillating chamber (2), characterised in that: the body (C) is realised in such a way as to comprise a first upper body (C1 ) and a second lower body (C2), wherein the second lower body (C2) is arranged in such a way as to be able to translate axially with respect to the body (C) and therefore with respect to the first upper body (C1 ), the auxiliary oscillating chamber (2) is made in the first upper body (C1) with an upper part of the auxiliary oscillating chamber (2), being comprised between the upper abutment surface (21) and the head (24) of the auxiliary piston (23), which is in communication with the pneumatic supply source (P1), the oscillating chamber (1) is made in the second lower body (C2), the rod (14) of the oscillating piston (10) being arranged so as to be slidable alternatingly in a passage channel (150) present in the second lower body (C2) which enables connection with the cutting blade (L), and the pneumatic activating system (P) is arranged and configured in such a way that, when the pneumatic activating system (P) is activated, a first part (1A) of the oscillating chamber (1), comprised between the head (13) of the oscillating piston (10) and the lower end-run wall (12), and a second part (1B) of the oscillating chamber (1), comprised between the head (13) of the oscillating piston (10) and the upper end-run wall (11), are placed in communication alternatively with the pneumatic supply source (P1) and with the at least a discharge (S1, S2), to pneumatically activate the head (13) of the oscillating piston (10) to oscillate inside the oscillating chamber (1) between the lower end-run wall (12) and the upper end-run wall (11), and therefore cause the rod (14) and consequently the cutting blade (L) to oscillate vertically between the lower cutting position (L1) and the upper cutting position (L2), the first upper body (C1) comprises a sliding channel (CS), communicating with the auxiliary oscillating chamber (2) via the lower abutment surface (22) and with the rod (25) of the auxiliary piston (23) which is arranged slidably in the sliding channel (CS) and connected, at a lower end, to the second lower body (C2), and in that the cutting device comprises elastic pushing means (3), arranged and configured in such a way as to act on the head (24) of the auxiliary piston (23) to exert on the head (24) of the auxiliary piston (23) a push towards the upper abutment surface (21) of the auxiliary oscillating chamber (2) in such a way that, with the pneumatic activating system (P) not operating, the auxiliary piston (23) is maintained in a raised position (PS) and thus maintain, by means of the respective rod (25), the second lower body (C2) in a raised position (TS) with respect to the body (C) in which the cutting blade (L) is in a raised non-operating position (LR), so that: when the pneumatic activating system (P) is activated, and the pneumatic supply source (P1) is in communication with the upper part of the auxiliary oscillating chamber (2), the head (24) of the auxiliary piston (23) is pushed downwards, compressing and loading the elastic pushing means (3), into abutment against the lower abutment surface (22) of the auxiliary oscillating chamber (2) and thus the rod (25) of the auxiliary piston (23) pushes downwards and positions the second lower body (C2) in a lowered position (TA) with respect to the body (C) in which the cutting blade (L) can contact and penetrate into the leather sheet to be cut, and the head (13) of the oscillating piston (10) is activated to oscillate in the oscillating chamber (1), between the lower end-run wall (12) and the upper end- run wall (11), to activate the cutting blade (L) in oscillation between the lower cutting position (L1) and the upper cutting position (L2) in order to carry out the cutting operations on the leather sheet to be cut; and when the pneumatic activating system (P), and therefore the pneumatic supply source (P1) are deactivated, the elastic pushing means (3) push the head (24) of the auxiliary piston (23) upwards, to return the head (24) into the respective raised position (PS), with a contemporary raising of the rod (25) of the auxiliary piston (23) upwards which raises and returns the second lower body (C2), with the oscillating chamber (1) and the oscillating piston (10) internal thereof, into the respective raised position with respect to the body (C), in such a way that the cutting blade (L), which is connected to the oscillating piston (10), can be raised and returned into the raised non-operating position (LR) above the upper cutting position (L2) thereof beyond the thickness of the leather sheet (V) and thus be extracted and disengaged completely from the leather sheet (V).

2) The cutting device (100) of claim 1, wherein the elastic pushing means (3) are arranged and configured in such a way as to act on the head (24) of the auxiliary piston (23) to exert on the head (24) of the auxiliary piston (23) a push towards the upper abutment surface (21) of the auxiliary oscillating chamber (2) in such a way that, with the pneumatic activating system (P) not operating, the auxiliary piston (23) is maintained in the raised position (PS) inside the auxiliary oscillating chamber (2) in which, with the respective head (24) thereof, it is in abutment against the upper abutment surface (21 ) of the auxiliary oscillating chamber (2). 3) The cutting device (100) of any one of the preceding claims, wherein the first upper body (C1), the second lower body (C2) and the rod (25) of the auxiliary piston (23) are dimensioned and reciprocally arranged in such a way that, with the pneumatic activating system (P) not operating and with the elastic pushing means (3) maintaining the auxiliary piston (23) in the raised position (PS) inside the auxiliary oscillating chamber (2), the second lower body (C2) is in the raised position (TS) in abutment and pressed against the first upper body (C1).

4) The cutting device (100) of any one of the preceding claims, wherein the body (C) comprises an outer jacket (CA), wherein the first upper body (C1) is fixedly mounted internally of the outer jacket (CA) and the second lower body (C2) is mounted internally of the outer jacket (CA) slidably by means of at least a respective sliding guide (GA).

5) The cutting device (100) of any one of the preceding claims, wherein: the rod (14) of the oscillating piston (10) is conformed so as to have: two annular portions (141, 142) in sliding contact with the walls of the passage channel (150) of the second lower body (C2) and an annular recess (140) comprised between the two annular portions (141, 142), an internal conduit (17) and being provided with through-holes (18) arranged in a position below the annular recess (140) so as to place the outside of the rod (14) in communication with the internal conduit (17); the head (13) of the oscillating piston (10) is provided with at least a through-hole (130) to place the internal conduit (17) of the rod (14) in communication with the second part (1B) of the oscillating chamber (1) comprised between the head (13) of the oscillating piston (10) and the upper end-run wall (11) of the oscillating chamber (1); the pneumatic activating system (P) being made and configured in such a way as to comprise: a main supply conduit (7), arranged in the body (C) in such a way as to be in communication with the pneumatic supply source (P1) and with the upper part of the auxiliary oscillating chamber (2) via a hole (70) present in the upper abutment surface (21 ) of the auxiliary oscillating chamber (2); a first auxiliary supply conduit (71), realised internally of the rod (25) of the auxiliary piston (23) and communicating with the part of the auxiliary oscillating chamber (2) above the head (24) of the auxiliary piston (23) via a service hole (72) realised in the head (24) of the auxiliary piston (23); a switching chamber (8) in a portion of the walls of the passage conduit (150) present in the second lower body (C2), a second auxiliary supply conduit (73) arranged in the second lower body (C2) so as to be in communication with the first auxiliary supply conduit (71) and with a lower part (81 ) of the switching chamber (8), a third auxiliary supply conduit (74) arranged in the second lower body (C2) so as to be in communication with an upper part (82) of the switching chamber (8) and with the oscillating chamber (1) via a passage hole (83) in the lower end-run wall (12) of the oscillating chamber (1 ), an upper discharge (S1) communicating with outside realised in the second lower body (C2) in a position above the switching chamber (8) and a lower discharge (S2) communicating with the outside made in the second lower body (C2) in a position below the switching chamber (8); the annular recess (140) of the rod (14) having dimensions so that, and with the holes (18) of the rod (14) being positioned with respect to the annular recess (140) in such a way that, with the activation of the pneumatic supply source (P1) and the activation in oscillation of the oscillating piston (10) and the alternating sliding of the rod (14) of the oscillating piston (10) in the passage channel (150) of the second lower body (C2): when the annular recess (140) of the rod (14) is positioned at the switching chamber (8), the holes (18) of the rod (14) are positioned at the lower discharge (S2), so that the second auxiliary supply conduit (73) is in communication, via the annular recess (140), with the third auxiliary supply conduit (74) and therefore the pneumatic supply source (P1) is in communication with the first part (1A) of the oscillating chamber (1) between the head (13) of the oscillating piston (10) and the lower end-run wall (12), while the second part (1B) of the oscillating chamber (1) between the head (13) of the oscillating piston (10) and the upper end-run wall (11) is in communication with the lower discharge (S2) via the at least a hole (130) of the head (13) of the piston (10), the internal conduit (17) of the rod (14) and the holes (18) of the rod (14), so that the oscillating piston (10) can be pneumatically pushed upwards; and when the annular recess (140) of the rod (14) is positioned at both the upper discharge (S1) and the upper part (82) of the switching chamber (8) communicating with the third auxiliary supply conduit (74), the holes (18) of the rod (14) are at the lower part (81) of the switching chamber (8) and are in communication with the second auxiliary supply conduit (73), so that the pneumatic supply source (P1), via the holes (18) of the rod (14), the internal conduit (17) of the rod (14) and the at least a through-hole (130) present in the head (13) of the oscillating piston (10) is in communication with the second part (1B) of the oscillating chamber (1) between the upper end-run wall (11) and the head (13) of the oscillating piston (10), while the first part (1A) of the oscillating chamber (1) between the head (13) of the oscillating piston (10) and the lower end-run wall (12) is in communication with the upper discharge (S1) via the passage hole (83) and the third auxiliary supply conduit (74), so that the oscillating piston (10) can be pneumatically pushed downwards.

6) The cutting device (100) of claim 5, wherein the pneumatic activating system (P) comprises at least a first discharge conduit (91), which is made in the second lower body (C2) so as to be in communication with the lower discharge (S2) and the upper discharge (S1), and with the outside.

7) The cutting device (100) of claim 6, wherein the pneumatic activating system (P) comprises a second discharge conduit (92) which is made in the first upper body (C1) and is in communication with the outside, wherein the first discharge conduit (91) and the second discharge conduit (92) are arranged in such a way as to be mutually in communication.

8) The cutting device (100) of claim 7, wherein, when the pneumatic activating system (P) is activated, and the pneumatic supply source (P1) is in communication with the upper part of the auxiliary oscillating chamber (2), to push and position the second lower body (C2) in the lowered position (TA) with respect to the body (C), internally of the body (C), a chamber (95) is defined between the first upper body (C1) and the second lower body (C2) via which chamber (95) the first discharge conduit (91) is in communication with the second discharge conduit (92).

9) The cutting device (100) of claim 7, wherein when the pneumatic activating system (P) is deactivated, and the elastic pushing means (3) push the head (24) of the auxiliary piston (23) upwards in order to position the auxiliary piston (23) into the raised position (PS) inside the auxiliary oscillating chamber (2), and the second lower body (C2) is in the respective raised position (TS) with respect to the body (C), the first discharge conduit (91) is directly facing and in communication with the second discharge conduit (92). 10) The cutting device (100) of any one of the preceding claims, wherein the lower part of the auxiliary oscillating chamber (2) is in communication with the outside via a service conduit (98).

11) The cutting device (100) of claim 10 and claim 7, wherein the service conduit (98) is connected to and in communication with the second discharge conduit (92) realised in the first upper body (C1 ).

12) The cutting device (100) of any one of the preceding claims, wherein the elastic pushing means (3) comprise a compression spring (30) arranged coaxially to the rod (25) of the auxiliary piston (23) and wherein the sliding channel (CS) is made in such a way as to comprise an annular chamber (31) for the positioning of the compression spring (30).