LEATHER PUNCHING MACHINE

Technical Field

[1] The present invention concerns a machine for punching leather, or a sheet material in general, suitable to perform punching, impressing, plating, etching, in which the sheet material to be machined moves forward lying on a conveyor belt which brings it to a processing section of the machine between a tool holder head mounted on a upper crosspiece driven with a reciprocating movement to perform a work stroke, and an abutment plane.

Background Art

[2] In the field of production of footwear or, in general, of leather products, it is

common, as known, the use of leather or the like on which are carried out special finishing operations aimed to confer a particular aesthetic appearance to the final product. This is referred, in particular, to the processing suitable for producing incisions or perforations having a well-defined geometric pattern repeated over the entire surface of the product, as well as for impressing the outer surface or for applying plating materials, having various shapes and sizes, distributed evenly over the surface.

[3] In order to obtain the repetition of the ornamental design over the entire surface of the sheet material they are currently employed machinery adapted to perform the above processing in a sufficiently precise and automatic way.

[4] These conventional machines, referred to generically as punching machines, essentially include: two uprights; an upper crosspiece mounted on the uprights to slide vertically; a tool holder head mounted at the lower side of the upper crosspiece so that machining tools projects down from the lower end of the upper crosspiece; drive members of the upper crosspiece to determine the vertical sliding of the upper crosspiece relative to the uprights so as to make them perform a reciprocating movement of ascent and descent which constitutes the work stroke of the tool holder head; a lower crosspiece; an abutment assembly mounted on the lower crosspiece comprising an abutment plane arranged substantially horizontal on the vertical of the tool holder head and vertically adjustable; components for adjusting the work depth suitable to adjust the vertical position of the horizontal abutment plane to adjust the work depth corresponding to the distance between the work surface of the tools of the tool holder head and the horizontal abutment plane when the tool holder head is located in a position of lower end stroke; a conveyor assembly comprising a conveyor belt which runs from a first roller with a horizontal axis placed at an input side of the machine, pass through a processing section of the machine in a unwound configuration lies on the abutment plane and interposed between the abutment plane itself and the tool holder head, and is rewound on a second roller with a horizontal axis arranged at the output side of the machine; feeding means of the conveyor belt that regulate the unwinding of the conveyor belt at the first roller, the feeding of the conveyor belt in the unwound configuration in the processing section, corresponding to an advance movement of the processing, and the rewinding of the conveyor belt on the second roller.

[5] The sheet materials to be worked are laid sequentially on the conveyor belt in the unwound configuration at the input side of the machine, they are then dragged by the advancement of the conveyor belt through the processing section and then they exit the machine, still in consequence of the conveyor belt's advancement, at the output side of the machine before the conveyor belt to rewind about the second roller. In the processing section, the reciprocating vertical movement of the tool holder head brings the tools to move perpendicularly with respect to the abutment plane on which the conveyor belt runs so that the tool in its downwards stroke comes to interact with the sheet material to perform the planned processing that is cutting, punching, impressing or the like, which mainly depends on the geometry of the tool and the machining depth set.

[6] Conventional machinery as described above, although they are able to perform on the leather, or sheet materials in general, a wide range of processes, have significant limitations in the ability to perform specific machining operations where the tool must interact with the material being processed with a movement not orthogonal to the latter but rather inclined, parallel or tangential, such as in carving, engraving, scratching processes or the like. In fact, in conventional punching machines, the above kind of processes can be performed by coordinating the machining movement of the tool holder head with the advancement movement of the conveyor assembly, and however the quality and variety of processes of this type that can be achieved is very limited. Disclosure of Invention

Summary of the Invention

[7] The object of the present invention is to propose a machine for performing

machining of sheet materials, such as leather, synthetics or the like, which allows to effectively execute processing in which the machining movement consists in a relative movement between the tool and the material being processed which is not orthogonal to the surface of the processed material itself, such as for example in the case of carving, engraving, scratching processes or the like.

[8] A further object of the invention is to propose a machine for the machining of sheet materials that is extremely versatile, i.e. with which it is possible to effectively perform a wide range of processes.

[9] Another object of the present invention is to propose a machine for the processing of sheet materials with which it is possible to simultaneously perform processes of carving and moulding, and in particular the processing of so-called 'reptile scales' is intended to reproduce on the leather the effect of scales of the reptile's skin.

[10] The above objects, and others, are achieved by a machine for machining sheet materials, such as leather, synthetics or the like in accordance with what is stated in claim 1.

Conventionally, a machine for the machining of sheet materials comprises at least two uprights, a movable upper crosspiece mounted on said uprights in sliding mode, a tool holder head mounted on the upper crosspiece so that tools project downward from the lower end of the upper crosspiece, drive members of the upper crosspiece to cause its sliding relative to the uprights so as to make them perform a reciprocating movement which is a work stroke of the tool holder head, a workpiece support assembly mounted below the upper crosspiece in correspondence of the latter and comprising an abutment plane disposed substantially perpendicular to the direction of movement of the tool holder head; set members for adjusting the work depth suitable to adjust the position of the abutment plane relative to the tool holder head, a conveyor assembly comprising a conveyor belt that crosses in a unwound configuration above the abutment plane through a machine processing section between the tool holder head and the abutment plane, with the sheet material workpiece that is fed to the machine processing section while lying down on the conveyor belt.

According to a peculiar aspect of the present invention, the abutment plane is arranged inclined with respect to the direction of the work stroke of the tool holder head by an angle of between 10° and 60°, and the tool holder head comprises tools shaped so that a work end portion of the tool has a working surface adapted to come into contact with the workpiece comprising at least a flat portion parallel to the abutment plane.

The abutment plane inclined with respect to the direction of the machining movement, associated with a tool having contact surface with the workpiece parallel to the abutment plane (and therefore to the surface of the workpiece) allows to perform carving operations with cuts that penetrate into the workpiece in a direction not perpendicular to its thickness.

Advantageously, the flat portion of the working surface of the tool is provided with a rounded and / or chamfered outer perimeter and an inner perimeter comprising at least one portion having a cutting edge.

The geometry of the tool allows having a portion of the working surface of the tool that exerts a pressure on the workpiece without cutting it, and at least one cutting edge that creates a cut.

Still advantageously, the abutment plane is elastically yielding, preferably constituted by a thick steel element or other substantially rigid material, superiorly coated with a material having high resilience such as synthetic rubber or the like.

The elasticity of the abutment plane allows to partially absorbing the force with which the tool acts on the workpiece, thus allowing to simultaneously obtain on the material a moulding operation and a carving operation.

Still advantageously, the tool holder head is constrained to the upper crosspiece to slide in the direction of the length of the crosspiece itself, and the machine comprises second drive members adapted to perform the sliding movement of the tool holder head with respect to the upper crosspiece.

[19] Thanks to the possibility of adjusting the transverse position of the tool holder head it is possible to expand the range of machining operations executable or alternatively reduce the total number of tools mounted on the tool holder head with a consequent reduction of the cost thereof.

Description of Drawings

[20] These and other advantages and characteristics of the machine of the present

invention will be immediately understandable from the following detailed description of a specific embodiment of the invention, given purely as an example but not limitative, with the help of the enclosed drawings, in which:

• Figure 1 is a perspective view from the input side of a machine according to the invention;

• Figure 2 is a schematic front view from the output side of the main

components of the machine of fig. l;

• Figure 3 is a schematic side sectional view of the machine of Fig.l;

• figure 4 is a view in detail of FIG. 3 showing a processing section of the

machine of Fig. 1: FIG. 4a shows the tool holder head in the position of upper end stroke, FIG. 4b shows the tool holder head in the position of lower end stroke;

• Figure 5 is a detail of FIG. 4b;

• Figure 6 shows a side section of a tool of a tool holder head associated with the machine of fig.l;

• Figure 7 is a bottom view of the tool of Fig.6.

Description of Preferred Embodiments

[21] With reference to Figures 1 to 3 it is shown as a whole with 10 a machine for

processing sheet materials, such as leather, synthetics or the like. In Figure 1, the machine 10 is represented in a perspective view in its complete configuration with casings and protections. In Fig. 2 and 3 are shown schematic views of the same machine 10 of which is shown only the mechanical structure and the main

components, with omission of the protective casings, of electrical and electronic parts and other components which are not essential to the disclosure of the present invention. The structure of the machine comprises essentially two parallel uprights, 12,

13, secured together, in this embodiment of the invention, by means of a lower shelf,

14, apt to support, inter alia, a workpiece support assembly, 20, and an upper fixed cross member, 15.

[22] A movable crosspiece, 30 is connected to the side uprights 12, 13 to slide vertically with respect to these by means of slide guides, 31, while remaining interposed between the upper cross member 15 and the support assembly 20. The drive members, 40, adapted to perform the vertical reciprocating movement of the movable crosspiece 30 comprise two crank mechanisms located externally to the uprights 12 and 13 and driven by a motor, 41.

[23] The movable crosspiece 30 inferiorly supports a tool holder head, 50, constrained to it for sliding in the transverse direction of the machine, corresponding to the direction of the length of the movable crosspiece 30 itself. The tool holder head 50, shown in detail in Fig. 4, is fixed to the movable crosspiece 30 by means of two slide guides, 51, 52, and inferiorly supports a plurality of tools, 60, which protrude downwards, i.e. towards the support assembly 20. Second drive members, 53, are provided integral with one of the crank mechanisms of the first drive members 40, to interface with the tool holder head 50 and operate the movement in the transverse direction with respect to the movable crosspiece 30 and therefore also with respect to the support assembly 20.

[24] A conveyor assembly 70, comprises a conveyor belt, 71, which unwinds from a supply log, 72, mounted on an unwinding roller, 73, placed with a horizontal axis at the input side of the machine 10, advances in the unwound configuration through a processing section, 80, of the machine between the tool holder head 50 and the support assembly 20, and is finally rewound on a return log, 74, mounted on a winding roller, 75, arranged with its axis horizontal at the output side of the machine 10. The workpieces, P, to be machined are loaded in a flat configuration on the conveyor belt 71 at a portion of it in which it runs horizontal at the input side of the machine 10 so as to identify a load surface, C. The advancement of the conveyor belt carries the sheet material P in correspondence with the processing section 80 in which the conveyor belt lies above the support assembly 20. Once processed, the further advancement of the conveyor belt 71 carries the workpiece P to be discharged on a discharge tray, S, suitably arranged at the output side of the machine 10. In order to feed the conveyor belt along the path described above, the conveyor assembly 70 visible in FIGS. 1 and 3 obviously comprises pulling means, deflection rollers, support rollers, tensioners and support brackets, only schematically depicted and not indicated with numerical references as of substantially known technique. In addition, as it can be seen, in FIG. 2, the conveyor assembly 70 has been completely omitted in order to make them more visible and intelligible the other components described above of the machine.

[25] The support assembly 20 comprises one or more support groups each being adjustable in vertical direction and each comprising a lower sloped plane element, 21, an upper sloped plane element, 22, and organs for adjusting the work depth, 23, through which, as shown by the arrows in FIG. 4b, varying the position in the direction input- output of the machine it is changed the position in height of the upper sloped plane element 22 and therefore the position of the abutment member, 24, supported by it. As mentioned, there can be a single supporting assembly extending transversely over the entire length of tool holder head 50, or may be multiple support groups placed side by side transversely to one another to allow for more independent adjustment of the work depth in respective cross sections of the machine. The abutment member 24 comprises an upper slide surface, 25, for letting the conveyor belt 71 slide and an abutment plane

26, which extends on the vertical of the tool holder head 50. While in the machines of the known art a slide surface of the conveyor belt and an abutment plane of the tool holder head are substantially coplanar and horizontal, in the present invention, the slide surface 25 is substantially horizontal, while the abutment plane is adjacent to this but downwards sloped. In the embodiment represented the abutment plane 26 forms with a vertical direction, and with a direction of movement of the tool holder head 50, an angle of 35°. More generally, according to the present invention, the abutment plane 26 forms with a direction of movement of the tool holder head 50 an angle of between 10° and 60°. The abutment member 24 is advantageously made of steel or another material with similar mechanical properties, and the relative slide surface 25 and the abutment plane 26 are identified by a coating made with an highly resilient element,

27, such as a carpet in synthetic rubber, able to undergo an elastic deformation under the action of the tools 60 thus softening the force they exert on the workpiece P. The highly resilient element 27 is constrained to the abutment member 24 in removable mode, for example by threaded members, in such a way as to be easily replaced in case of wear or breakage.

[26] One or more tools 60 protrude downward from the tool holder head 50 in the

processing section 80 of the machine. With reference to Figures 6 and 7, the tools 60 in the embodiment depicted are constituted by a plurality of punches aligned in the transverse direction in two rows, and more exactly a first row of tools, 60a, disposed upstream in the advancement direction of the conveyor belt 71 and a second row of tools, 60b, arranged downstream of the first in the direction of advance of the conveyor belt 71. Each tool 60 has generally cylindrical outer shape with an end portion of work, 61, internally hollow. The work end portion 61 has a work surface 62 of the tool, adapted to come into contact with the workpiece P, comprising at least a flat portion, 63, parallel to the abutment plane 26. The work surface 62 of the tool is further provided with an outer perimetral portion, 64, adapted to connect without forming sharp edges the flat portion 63 with an outer lateral surface, 65, of the work end portion 61, and an inner perimeter comprising an inner rounded perimetral portion, 66, adapted to connect without forming sharp edges the flat portion 63 with an inner lateral surface, 67, of the work end portion 61, and an inner cutting perimetral portion, 68 , suitable to form a sharp edge between the flat portion 63 and the inner lateral surface 67. The flat portion 63 of the tools 60a of the upstream row of tools is coplanar with the flat portion 63 of the tools 60b of the downstream row of tools and thus the tools 60a of the upstream row process the workpiece P simultaneously to the tools 60b of the downstream row of tools and with the same work depth.

[27] The reciprocating movement of the movable crosspiece 30 drives the reciprocating work movement of the tools 60 consisting of a downward stroke of working and a return upward stroke. In FIG. 4a, the tools are shown in the position of upper end stroke where they are appropriately spaced from the abutment plane 26, and then from the conveyor belt 71 that runs on it and the workpiece P disposed on the latter. In Fig. 4b and in the detailed view of Fig. 5 tools 60 are located in the lower end stroke position while performing a machining operation on the workpiece P. The flat portion 63 of the work surface of the tool is parallel to the abutment plane 26 and thus exerts a uniform pressure on the workpiece P by performing a process of moulding the same, while the inner cutting perimetral portion 68 exerts a cutting action not passing through. The highly resilient element 27 is elastically deformed and partially absorbs the forces with which the tool acts on the workpiece P allowing a particularly accurate adjustment of the processing parameters. The actual work depth takes into account the elastic deformability of the workpiece P and the highly resilient element 27.

[28] The embodiment described above has peculiar advantages and features, however, variants of the same and different embodiments of a machine for the machining of sheet material can of course be envisaged while remaining within the inventive concept of the present invention.

[29] For example, they may vary the shape and size of the machine structure, in

particular of the uprights, the cross members and of their organs of mutual constraint.

[30] The conveyor assembly may be of different types and arranged to take place

according to different paths than the one shown by way of example in Figures 1 and 3.

[31] The organs for adjusting the work depth 23 and second drive members 53 may also be very different, as regards both their structure and their operation mode, compared to those represented in the attached figures, or may not be present in a machine according to the present invention.

[32] The abutment plane 26 may be made of steel or another material with a substantially rigid behaviour under the action of forces exerted by the movable upper crosspiece 30 through the tools 60. Alternatively, rather than providing the coating element with high resilience 27 an abutment plane 26 elastically deformable could be achieved in different ways for example by adopting an abutment member 24 elastically deformable.

[33] The tools 60 mounted onto the tool holder head 30 may be in number, arrangement and geometry also very different than those described which are particularly suitable to perform the processing of so-called 'reptile scales' intended to reproduce on a leather the effect of the scales of the skin of reptiles through simultaneous and combined processes of moulding and carving without passing through.

[34] Other modifications and variations can obviously be made to what is illustrated by way of example, without its forsaking the ambit of protection sought for the inventive idea as claimed below.