Welding device and method for product packaging machines

Abstract

A welding device (1) for product packaging machines, comprising: a welding unit (110, 210) comprising a welding tool (110) and a countertool (210) mutually movable in rotation about an axis (A), the welding tool (110) defining at least one first active welding surface (111) and at least one second active welding surface (112), and the countertool (210) defining at least one first opposing surface (212) and at least one second opposing surface (213); a movement unit comprising at least one first movement device (220, 240) configured to mutually rotate the welding tool (100) and the countertool (200) about the axis (A) between a first welding configuration, in which the first active welding surface (111) and the first opposing surface (212) are held tightly together at a first welding surface (PS1) and the second active welding surface (112) and the second opposing surface (213) are spaced apart, and a second welding configuration, in which the second active welding surface (112) and the second opposing surface (213) are held tightly together at a second welding surface (PS2) and the first active welding surface (111) and the first opposing surface (212) are spaced apart.

Description

[0001] DESCRIPTION WELDING DEVICE AND METHOD FOR PRODUCT PACKAGING MACHINES.

[0002] Technical field

[0003] This invention addresses the technical field of automatic product packaging machines and relates, specifically, to a welding device and a welding method for product packaging machines, in particular, for automated welding of product wrappers, both discrete wrappers and flow pack wrappers.

[0004] Background art

[0005] In the packaging field, longitudinal and transverse welds are typically made using conventional systems such as, for example, hot air, cold and ultrasonic welding tools.

[0006] Generally speaking, welding is carried out by moving a tool and countertool towards each other, where the tool constitutes an active welding element while the countertool acts as an anvil against which the tool applies compression.

[0007] In traditional welding, the mutual movement between tool and countertool is a rectilinear translation, in particular along a direction perpendicular to the area to be welded.

[0008] In some situations, it is also necessary to make different welds which are adjacent to each other. An example of such a situation is making a hermetic weld adjacent to a cosmetic weld, used, for example, in the packaging of products where the purpose of the hermetic weld is to create a hermetic seal, while the purpose of the cosmetic weld is to join the two end edges defined by different layers and disposed on the outer side of the hermetic weld.

[0009] Different welds according to this requisite require different welding parameters (different pressures, temperatures, contact surfaces and so on) and this may be difficult to achieve precisely, since optimizing the movement for one weld means that the other weld is made in an unsuitable manner.

[0010] Currently known are devices for making a hermetic weld and a cosmetic weld, where a hermetic welding countertool and a cosmetic welding countertool are connected to each other in an articulated manner to define two distinct movement systems, suitable and optimized for making one hermetic weld and one cosmetic weld respectively.

[0011] The two countertools are movable relative to each other to selectively engage each countertool with the active welding surface (sonotrode). This engagement is accomplished by frontal impact between each countertool and the active welding surface, in particular keeping the front surfaces of the countertools parallel to each other and parallel to the active welding surface.

[0012] The Applicant has found that such a solution can be improved, particularly with to constructional complexity.

[0013] Moving two distinct countertools requires using two distinct mechanisms, which are usually very close together on account of the reduced size of the welding area.

[0014] Moreover, in these prior art solutions, one countertool is mounted in translatable or articulated manner relative to the other countertool so that by moving one countertool and performing a relative movement between the two countertools it is possible to make the two required welds. These two movements are distinct but intercorrelated and adjusting the welding parameters of one of the two countertools means necessarily having to also check the other countertool since the first is mounted relative to the second.

[0015] The Applicant has therefore found that, in a configuration in which the welding tool defines at least a first active welding surface and a second active welding surface and in which the countertool defines at least a first opposing surface and a second opposing surface, performing a relative rotation between the welding tool and the countertool about an axis allows obtaining a first welding configuration, in which the first active welding surface and the first opposing surface are pressed together while the second active welding surface and the second opposing surface are spaced apart, and a second welding configuration, in which the second active welding surface and the second opposing surface are pressed together while the first active welding surface and the first opposing surface are spaced apart. Thus, a single, simple rotational movement, implementable with a single rotary actuating mechanism, allows controlling the two welding actions and governing the welding parameters of each of the two welds in a simple, compact manner.

[0016] According to a first aspect of it, therefore, this invention relates to a welding device for product packaging machines.

[0017] The device comprises a welding unit for making at least one weld on at least one web or sheet of material.

[0018] The welding unit comprises at least a welding tool and a countertool, where the tool defines at least a first active welding surface and a second active welding surface, while the countertool defines at least a first opposing surface and a second opposing surface.

[0019] The welding tool and the countertool are mutually movable in rotation about an axis between a first welding configuration, in which the first active welding surface and the first opposing surface are pressed together at a first welding surface while the second active welding surface and the second opposing surface are spaced apart, and a second welding configuration, in which the second active welding surface and the second opposing surface are pressed together at a second welding surface while the first active welding surface and the first opposing surface are spaced apart.

[0020] That way, a single rotational movement allows the device to be switched between the two welding configurations.

[0021] Preferably, the device also comprises a movement unit comprising at least a first movement device configured for performing a mutual rotation between the welding tool and the countertool about the axis between the first welding configuration and the second welding configuration.

[0022] Preferably, the first active welding surface and the first opposing surface face, or are or adapted to face, each other to compress the web or sheet during the first welding action. Preferably, the second active welding surface and the second opposing surface face, or are or adapted to face, each other to compress the web or sheet during the second welding action. The term "active welding surface" is used to mean the surface of a part which actively performs the welding operation, hence, for example, a heating element, a sonotrode or the like.

[0023] The expression "welding surface" is used to mean a surface, whether planar or otherwise configured, extending over the entire contact area between each active welding surface and the respective opposing surface. In other words, the device is configured to switch between the first and the second welding configuration by rotation about the axis.

[0024] Thanks to this mode of operation, a single rotational movement allows obtaining two different welds, controllable independently of each other, for example by setting different contact times, different contact pressures or other different parameters.

[0025] According to a second aspect of it, this invention relates to a welding method for product packaging machines.

[0026] The method is implemented by a device comprising a welding tool and a countertool positioned to face each other.

[0027] The welding tool defines at least a first active welding surface and a second active welding surface, while the countertool defines at least a first opposing surface and a second opposing surface.

[0028] Preferably, the first active welding surface and the first opposing surface face, or are or adapted to face, each other to compress the web or sheet during the performance of a corresponding first welding action. Preferably, the second active welding surface and the second opposing surface face, or are or adapted to face, each other to compress the web or sheet during the performance of a corresponding second welding action.

[0029] Preferably, the welding tool and the countertool are configured to make a first welding configuration, in which the first active welding surface and the first opposing surface are pressed together at a first welding surface while the second active welding surface and the second opposing surface are spaced apart, and a second welding configuration, in which the second active welding surface and the second opposing surface are pressed together at a second welding surface while the first active welding surface and the first opposing surface are spaced apart.

[0030] Preferably, the active welding surface and the opposing surface are mutually movable in rotation about an axis.

[0031] Preferably, this is achieved by mutually rotating the welding tool and the countertool about the axis.

[0032] Preferably, the active welding surface and the opposing surface are mutually movable in rotation about the axis between a disengaged configuration in which the active welding surface is spaced from the opposing surface, and a welding configuration, in which the active welding surface and the opposing surface are pressed together at a welding surface.

[0033] Preferably, the method comprises positioning the welding surface and the opposing surface in the disengaged configuration, where at least one sheet or web to be welded is interposed between the welding surface and the opposing surface.

[0034] Preferably, the method also comprises mutually rotating the welding tool and the countertool about the axis until reaching the welding configuration, thus welding the at least one sheet or web.

[0035] The welding tool and the countertool are mutually movable between the first and second welding configurations, in rotation about an axis.

[0036] Preferably, the method is carried out in the following steps: - positioning the welding tool and the countertool to face each other, with at least one sheet or web to be welded interposed between the active welding surfaces and the opposing surfaces;

[0037] - positioning the welding tool and the countertool relative to each other in the first welding configuration so as to make a first weld on the sheet or web at the first welding surface;

[0038] - performing a relative rotation between the welding tool and the countertool about the axis until reaching the second welding configuration, to make a second weld on the sheet or web at the second welding surface.

[0039] Thanks to this method, a single rotational movement allows obtaining two different welds, controllable independently of each other, for example by setting different contact times, different contact pressures or other different parameters.

[0040] According to least one of the above mentioned aspects, this invention may also comprise at least one of the preferred features described below.

[0041] Preferably, in the case of rotation of the welding tool, the first and the second active welding surfaces are movable in their entirety in rotation and together about the axis.

[0042] Preferably, in such a case the first and the second active welding surfaces are fixed to each other (permanently) and thus move in rotation as one about the axis. In particular, the first and the second active welding surfaces are defined by a single welding tool which is monolithic and / or rotatable in its entirety about the axis.

[0043] Preferably, in the case of rotation of the countertool, the first and the second opposing surfaces are movable together in rotation about the axis. Preferably, in such a case the first and the second opposing surfaces are fixed to each other (permanently) and thus move in rotation as one about the axis. In particular, the first and the second opposing surfaces are defined by a single countertool which is monolithic and / or rotatable in its entirety about the axis. Preferably, the axis is substantially parallel to the first welding surface and / or to the second welding surface.

[0044] Preferably, the first and the second welding surfaces lie substantially in respective planes. By "substantially" is meant, in this circumstance, the general form of the surfaces, it being understood that such surfaces may have localized or distributed protrusions or recesses such as, in any case, to define an essentially planar shape.

[0045] By "substantially parallel" is meant an inclination of between + / -100, preferably between + / -5° and still more preferably 0°, between an axis and a surface, between axes or between surfaces.

[0046] In the case of surfaces with non-planar shapes, the concept of parallelism is understood as referring to a mean plane of the surfaces. For example, in the case of a surface with a curved shape, be it convex or concave, symmetrical about a plane of symmetry through the concavity or convexity, the mean plane is understood as being perpendicular to that plane of symmetry. In the case of a complex surface made up of two or more concave / convex surfaces, the concept of parallelism is understood as referring to the mean planes of the surfaces.

[0047] More generally speaking, the term "mean plane" is used to denote the positioning plane of the coupled set to be welded (or a plane parallel to it) before reaching the welding configuration, hence before each active welding surface and the respective opposing surface are pressed against each other, where such mean plane intersects the active welding surface and / or the opposing surface in the welding configuration.

[0048] Thanks to the parallelism, the moving parts engage each other in a balanced manner, thus obtaining a balanced weld on the material.

[0049] Preferably, the axis is substantially coplanar with the first and / or the second welding surface. This allows creating a first welding motion arrangement which is particularly effective in obtaining a geometrically correct engagement between each active welding surface and the respective opposing surface. Alternatively, the axis is spaced from the first and / or the second welding surface, while preferably remaining parallel to it. This creates a different welding motion arrangement which is particularly effective in obtaining a geometrically correct engagement between each active welding surface and the respective opposing surface.

[0050] Preferably, the at least one first movement device is configured for performing a first alternate rotation of the welding tool and / or of the countertool about the axis between the first and the second welding configurations. This is linked to the presence of the two movement end positions of the welding tool and / or of the countertool, which determine the action radius of the first movement device. This feature has the advantage of providing a shared movement device for both configurations, which can independently control the process parameters in the two welding configurations, optimizing each of them as a function of requirements.

[0051] Preferably, the two active welding surfaces lie in respective planes making an angle of between 30° and 175°, and still more preferably, between 90° and 170°. This optimizes the effect of welding efficacy, while at the same time making it possible to simplify the technical means necessary for rotation, which need to perform only a limited rotation.

[0052] Preferably, this angle faces towards the inside of the welding tool. In other words, the welding tool is preferably convex, that is to say, has a substantially "wedge-like" shape.

[0053] In this situation, the two opposing surfaces of the countertool may present a concave configuration (making an angle which is larger than the angle between the two active welding surfaces) or may be coplanar or parallel with each other.

[0054] Alternatively, the angle preferably between 30° and 175°, and still more preferably between 90° and 170° is made between the positioning planes of the two opposing surfaces.

[0055] Preferably, this angle faces towards the inside of the countertool. In other words, the countertool is preferably convex, that is to say, has a substantially "wedge-like" shape.

[0056] In this situation, the two active welding surfaces of the welding tool may present a concave configuration (making an angle which is larger than the angle between the two opposing surfaces) or may be coplanar or parallel with each other.

[0057] Disclosure of the invention

[0058] Preferably, the welding unit is configured to make, at the first and the second opposing surfaces, respective welds which differ in structure and / or kind, being in particular a hermetic weld and a cosmetic weld.

[0059] Preferably, the axis is kept stationary relative to the welding surfaces at least during the mutual rotation between the welding tool and the countertool about the axis itself.

[0060] Preferably, the at least one first movement device is also configured to mutually rotate the welding tool and the countertool about the axis so as to form a disengaged configuration, in which the first active welding surface is spaced from the first opposing surface and in which, at the same time, the second active welding surface is spaced from the second opposing surface.

[0061] Preferably, in such a situation, the disengaged configuration is intermediate between the first and the second welding configurations and the first and the second welding configurations are defined by opposite rotations of the welding tool and / or of the countertool about the axis. This allows providing at least one intermediate position which is distinct from the two welding configurations and which is suitable for defining a standby or approach configuration between the material to be welded and the welding unit. Consequently, starting from the disengaged configuration, it is possible to make the two welds in succession by two opposite rotations about the axis, the first rotation being from the disengaged configuration to the first welding configuration and the second rotation being from the first welding configuration to the second welding configuration. A subsequent rotation from the second welding configuration to the disengaged configuration can also be performed to define an "exit" or end-of-welding movement suitable for drawing the welded material away from the welding area.

[0062] In other words, therefore, the disengaged configuration is an intermediate configuration between the first and second welding configurations, which occurs operatively between the two welding actions.

[0063] Preferably, the welding tool and the countertool are disposed at the disengaged position even before reaching the first welding configuration and making the first weld and / or after reaching the second welding configuration and making the second weld.

[0064] Preferably, the at least one first movement device comprises a support, to which the welding tool and / or the countertool is rotatably connected and at least one actuator for moving the welding tool and / or the countertool in rotation relative to the support. This configuration produces a simple, robust structure, defining a constrained rotation guide for the tool and / or the countertool and at the same time defining stable anchoring points for the actuator.

[0065] Preferably, the support is rotatably connected to the welding tool and / or to the countertool via a fulcrum or an arcuate guide. The presence of the fulcrum is structurally robust while the use of an arcuate guide is particularly advantageous in the case where the axis is positioned in a zone which is remote from the coupling zone between the support and the tool and / or the countertool.

[0066] In an embodiment, there is only a first movement device, operating on the welding tool. In such a case, the relative rotation between welding tool and countertool is given by the rotation of the welding tool only. This rotation is performed, in particular, between the welding tool and the respective support on which the welding tool is rotatably mounted.

[0067] In a different embodiment, there is only a first movement device, operating on the countertool. In such a case, the relative rotation between welding tool and countertool is given by the rotation of the countertool only. This rotation is performed, in particular, between the countertool and the respective support on which the countertool is rotatably mounted.

[0068] In a different embodiment, there are two movement devices, the first one operating on the welding tool and the second one operating on the countertool. In such a case, the relative rotation between welding tool and countertool is given by the rotation of the welding tool and by the rotation of the countertool.

[0069] Preferably, the movement unit also comprises at least a second movement device configured for performing a relative movement to draw the welding tool and the countertool towards / away from each other along a trajectory between a close-together configuration, in which welding tool and countertool are close together along the trajectory, and a spaced-apart configuration, in which welding tool and countertool are spaced apart along the trajectory.

[0070] This allows keeping the rotational movement, which is optimized for performing the welding actions, separate from the movement towards and away, which is functional to approaching the welding zone and the subsequent movement away which is intended to allow the welded material to be removed from the welding zone.

[0071] Preferably, the trajectory is incident on the welding surfaces. This produces a relative movement between welding tool and countertool by which they are drawn towards / away from each other in a direction transverse to the positioning plane of the material to be welded in the welding zone.

[0072] Preferably, the second movement device operates on the support in order to move the support along the towards / away trajectory. This constitutes an optimum separation between the mutual towards / away movement between welding tool and countertool, which is functional to preparing for welding and to removing the material, as well as to setting up as a function of size, and the rotational welding movement optimized as a function of the welding parameters.

[0073] In an embodiment, the second movement device operates on the support of the welding tool. In this situation, the welding tool is subjected to a rotation about the axis and a translation along the trajectory. The countertool may be stationary or also movable along the trajectory via an additional second movement device.

[0074] In an embodiment, the second movement device operates on the support of the welding tool. In this situation, the welding tool is subject only to a translation along the trajectory. The countertool may be stationary or also movable along the trajectory via an additional second movement device and is rotatable via the first movement device. In a different embodiment, the second movement device operates on the support of the countertool. In this situation, the welding tool is subjected to a rotation about the axis and a translation along the trajectory. The countertool may be stationary or also movable along the trajectory via an additional second movement device.

[0075] In a different embodiment, the welding tool is rotatably mounted on the respective support, which is stationary (fixed, preferably adjustable), while the countertool is mounted (preferably fixedly, i.e. not rotatably) on a respective support which is translatable along the trajectory, in particular via a respective actuator.

[0076] In a different embodiment, the countertool is rotatably mounted on the respective support, which is stationary (fixed, preferably adjustable), while the welding tool is mounted (preferably fixedly, i.e. not rotatably) on a respective support which is translatable along the trajectory, in particular via a respective actuator.

[0077] Preferably, the support is mounted on a guide and the at least one second movement device comprises a respective actuator connected to the support to move the support along the guide. Preferably, the guide is linear.

[0078] Preferably, the guide is rectilinear. In other words, the trajectory is preferably substantially rectilinear and transverse to the first welding surface and / or to the second welding surface. This orientation occurs at least in the close-together configuration.

[0079] Preferably, one between the welding tool and the countertool has a distal portion which faces towards the other between the welding tool and the countertool and which is adapted to define, in conjunction with the other between the welding tool and the countertool, a welding or cutting line or area substantially parallel to the axis. That way, the same structure and the same movement means can be used to perform an additional cutting and / or welding action on the material, as clarified below.

[0080] Preferably, the distal portion is a forward jutting zone of the welding tool or of the countertool.

[0081] Preferably, the distal portion is defined on the welding tool and is parallel to at least one of the active welding surfaces.

[0082] Alternatively, the distal portion is defined on the countertool and is substantially parallel to at least one of the opposing surfaces.

[0083] Preferably, the distal portion and / or the other between welding tool and countertool is configured in such a way as to define a weld which is different from the weld between each active welding surface and the respective opposing surface.

[0084] In an embodiment, this weld is in the form of a welding line, in particular a rectilinear segment.

[0085] Preferably, the distal portion is interposed between the active welding surfaces or between the opposing surfaces.

[0086] Preferably, in addition to, or instead of, the aforesaid distal portion, one between the welding tool and the countertool has a front protuberance facing the other between welding tool and countertool, and the other between welding tool and countertool has a front recess. The front protuberance and the front recess face each other to make, in the close- together configuration, the cut in sheet or web to be welded interposed between tool and countertool or, alternatively, a local bend in a sheet or web to be welded interposed between tool and countertool, where such a bend is suitable for stably holding the sheet or web to be welded during the mutual rotation between welding tool and countertool. This produces optimum quality, precise welds in that, in the case of cutting, the cut is made using the same components as those used for welding or, in the case of bending, the welds are made in a configuration such that the material is held in place securely and the material prevented from moving out of place or the different layers making it up from slipping out of place.

[0087] In the case of cutting, the front protuberance and / or the front recess are configured to make a cut and, for that purpose, they interact with a cutting action and / or at least one of them has a cutting element such as a blade, for example.

[0088] In the case of bending, the front protuberance and / or the front recess are configured to make at least one bend in the path followed by the at least one web or sheet to be welded.

[0089] In an embodiment, the front protuberance and the front recess are interposed between the respective active welding surfaces or the opposing surfaces. This configuration is optimal in particular in the case of front protuberance and front recess configured to make the bend in the web or sheet of material.

[0090] In a different embodiment, the front protuberance and the front recess are disposed on the outside of the respective active welding surfaces or opposing surfaces. In other words, one of the two active welding surfaces is included between front protuberance or front recess and the other active welding surface, and / or one of the two opposing surfaces is included between front protuberance or front recess and the other opposing surface. This configuration is optimal in particular in the case of front protuberance and front recess configured to make the cut in the web or sheet of material.

[0091] Preferably, front protuberance and front recess have respective main directions of extension parallel to the axis. This produces an optimum action for holding or cutting the web, an action compatible with the directions of extension of the welding surfaces.

[0092] Preferably, the device also comprises a conveyor movable along a movement path which is at least partially parallel and / or coplanar with the welding surfaces, and the welding unit and the movement unit are mounted on the conveyor and are movable along the movement path in such a way as to make a seam tracking weld.

[0093] The movement path is thus preferably transverse, more preferably perpendicular to the trajectory defining the relative movement between the welding tool and the countertool to draw them towards / away from each other. This optimizes the efficacy of the welding action performed by seam tracking.

[0094] In this situation, the device is operated by moving the welding unit and the movement unit along the movement path, and the mutual rotation between welding tool and countertool about the axis to make the weld is performed during the movement of the welding unit and movement unit along the movement path so as to make a seam tracking weld. In other words, mutually rotating the welding tool and the countertool about the axis is performed during the movement of the welding tool and the countertool along the movement path in such a way as to make a seam tracking weld. Preferably, the movement of the welding tool and the countertool along the movement path is accomplished by moving the welding tool and the countertool in a mutually synchronous manner along the movement path. The movement structure of welding tool and countertool is simplified and can be integrally mounted on the conveyor.

[0095] In an embodiment, the conveyor is a closed path conveyor, for example, a transfer wheel, in which the path preferably has a straight stretch in which welding occurs. In this case, the welding unit and the movement unit are moved along a closed path, more preferably circular or substantially circular (circular except for a straight stretch where welding is carried out).

[0096] In a different embodiment, the conveyor is a movable plate, with to-and- fro, reciprocating motion. In this case, the welding unit and the movement unit are moved back and forth along an open path which is preferably straight.

[0097] Preferably, the welding tool and the countertool are also configured to form a disengaged configuration, in which the first active welding surface is spaced from the first opposing surface and in which the second active welding surface is spaced from the second opposing surface, hence intermediate between the two welding configurations. In this situation, the method according to the invention also comprises disposing the welding tool and the countertool at the disengaged position before reaching the first welding configuration and / or after reaching the second welding configuration. That way, it is possible to obtain an infeed configuration and an outfeed configuration, respectively, suitable for allowing the welding unit to move on to the next region of material to be welded or to renew the material to be welded.

[0098] Preferably, therefore, the first and the second welding configurations are defined by opposite rotations of the welding tool and / or of the countertool about the axis relative to the disengaged configuration.

[0099] Preferably, the axis is kept stationary relative to the sheet or web to be welded at least during the mutual rotation between the welding tool and the countertool about the axis. This allows obtaining an optimum welding process in which there is a kinematic coupling between material to be welded and welding tool and countertool.

[0100] In an embodiment, the mutual rotation between the welding tool and the countertool about the axis is performed by rotating only the welding tool.

[0101] In a different embodiment, the mutual rotation between the welding tool and the countertool about the axis is performed by rotating only the countertool.

[0102] In an embodiment, the mutual rotation between the welding tool and the countertool about the axis is performed by rotating both the welding tool and the countertool, preferably simultaneously. Preferably, the method also comprises drawing the welding tool and the countertool towards / away from each other along a trajectory according to a relative movement towards / away from each other between a close- together configuration, in which welding tool and countertool are close together along the trajectory, and a spaced-apart configuration, in which welding tool and countertool are spaced apart along the trajectory (D). Preferably, the trajectory is incident on the welding surfaces.

[0103] In an embodiment, the relative movement between the welding tool and the countertool along the trajectory is performed by moving only the welding tool along the trajectory, while the countertool remains fixed along the trajectory. In this configuration, it is possible to impart the rotational movement about the axis only to the welding tool, only to the countertool or to both.

[0104] In a different embodiment, the relative movement between the welding tool and the countertool along the trajectory is performed by moving only the countertool along the trajectory, while the welding tool remains fixed along the trajectory. In this configuration, it is possible to impart the rotational movement about the axis only to the welding tool, only to the countertool or to both.

[0105] Preferably, the relative movement between the welding tool and the countertool along the trajectory comprises initially drawing the welding tool and the countertool closer together along the trajectory at least partly before mutually positioning the welding tool and the countertool in the first and / or the second welding configuration. Preferably, initially drawing the welding tool and the countertool closer together along the trajectory is carried out while the welding tool and the countertool are angularly positioned relative to each other in an intermediate configuration between the first and the second welding configuration, in particular the disengaged configuration.

[0106] Preferably, also, the relative movement between the welding tool and the countertool along the trajectory comprises drawing the welding tool and the countertool further apart along the trajectory after reaching the first and the second welding configuration.

[0107] Preferably, the relative movement between the welding tool and the countertool to draw them closer together along the trajectory comprises pressing a distal portion of one between the welding tool and the countertool against the other between the welding tool and the countertool to make a weld along a welding line or area substantially parallel to the axis. That way, it is possible to make a third weld thanks to the closer- together movement performed to prepare tool and countertool to make the two welds along the two welding surfaces.

[0108] Preferably, pressing the distal portion is carried out at least partially while the welding tool and the countertool are angularly positioned relative to each other in the intermediate configuration. That way, three welds, which may be, for example, of different kinds, can be made in sequence and separately.

[0109] Preferably, the weld made between the distal portion and the other between welding tool and countertool is different from the welds made between each active welding surface and the respective opposing surface. Preferably, such an additional weld may define a preliminary coupling between the layers of material to be welded or it may constitute an actual welding region, made alongside the other two and intended to fulfil a specific function on the end product.

[0110] Preferably, one between welding tool and countertool has a front protuberance facing the other between welding tool and countertool, while the other between welding tool and countertool has a front recess, where front protuberance and front recess face each other so that the relative movement between the welding tool and the countertool along the trajectory and / or the mutual rotation between the welding tool and the countertool about the axis produces, in the close-together configuration and / or in at least one of the welding configurations, a cut in at least one sheet or web to be welded interposed between welding tool and countertool and / or a local bend in at least one sheet or web to be welded, in a manner suitable for stably holding the sheet or web to be welded during the welding action.

[0111] This allows holding the layers of material in place while at the same time drawing the welding tool and the countertool closer together, in particular, in the case of a front protuberance located at an intermediate position between the active welding surfaces or the opposing surfaces and in the case of a front recess located at an intermediate position between the active welding surfaces or the opposing surfaces.

[0112] This, instead, allows making the cut in the material while at the same time performing the mutual rotation between welding tool and countertool and reaching at least one of the two welding configurations, where mutual engagement between front protuberance and front recess occurs.

[0113] Preferably, front protuberance and front recess have respective main directions of extension parallel to the axis.

[0114] Preferably, the method also comprises moving the welding unit and the movement unit along a movement path and mutually rotating the welding tool and the countertool about the axis is performed during the movement of the welding tool and the countertool along a movement path in such a way as to make a seam tracking weld.

[0115] The movement of the welding unit and the movement unit along a movement path can be performed by moving the welding unit and the movement unit synchronously with each other, in particular by mounting the welding unit and the movement unit on a conveyor which is movable along a closed line (for example, a transfer wheel) or on a movable support, with to-and-fro, reciprocating motion along the movement path so that the welding unit and the movement unit temporarily move at a speed synchronized with the material to be welded, thus making a seam tracking weld.

[0116] In a variant embodiment of the invention, the countertool is not an anvil but a second sonotrode. In this configuration, the first sonotrode defines a first active welding surface, while the second sonotrode defines a second active welding surface, the two active welding surfaces being pressed together on a welding surface in the welding configuration.

[0117] Brief description of drawings

[0118] Further features and advantages of this invention are more apparent in the following detailed description of preferred embodiments of it, with reference to the accompanying drawings.

[0119] In these drawings:

[0120] - Figure 1 is a perspective view of a welding device according to this invention in a non-operating configuration;

[0121] - Figure 2 is a perspective view of the device of Figure 1 in an operating configuration;

[0122] - Figure 3 is a perspective view of a component of the device of Figure 1 ;

[0123] - Figure 4 is a cross section of the device of Figure 1 in the non-operating configuration;

[0124] - Figures 5 and 6 are cross sections of the device of Figure 1 in two different operating configurations;

[0125] - Figures 7-9 are enlarged views of three sequential operating configurations of the welding device of Figure 1 ;

[0126] - Figures 9-13 are enlarged views of a detail of the welding device of the invention, according to variant embodiments of it.

[0127] Detailed description of preferred embodiments of the invention

[0128] With reference to the accompanying drawings, the numeral 1 denotes in its entirety a welding device according to the invention.

[0129] The welding device 1 comprises a tool block 100 and a countertool block 200 facing each other at a position such as to define between them a passage for at least one web or sheet to be welded.

[0130] In the context of this invention, by "at least one web or sheet to be welded" is meant a coupled set of two or more layers, either the same or different from each other, overlapped to be joined to each other by welding. The two or more layers may be defined by different portions of a single web or sheet (for example, when forming a tube or when a tube is transversely welded) or by two or more different, overlapped webs or sheets. Additionally, the invention is applicable both to precut sheets or segments and to continuous webs. In the accompanying drawings, the web or sheet to be welded is shown in the form of an end edge of a product P in the form of a pouch or packet.

[0131] The tool block 100 and the countertool block 200 may be mounted on the same machine frame or on different frames.

[0132] The tool block 100 comprises a welding tool 110 which, in the drawings, is illustrated in the form of an ultrasonic tool but which may be in other forms (for example, a hot air welder, a cold welder or an induction welder). The tool block 100 also comprises a support 120, on which the welding tool

[0133] 110 is mounted and a base 130 on which the support 120 is mounted. In the embodiment illustrated, the support 120 is coupled to the base 130 by a sliding guide defining a translational, preferably rectilinear, trajectory D. For this purpose, the support 120 and the base 130 may be connected to each other by a guide 140, in particular a linear sliding guide, for example, a dovetail guide or a bar-sleeve guide. The support 120 is made to slide on the base 130 by an actuator, not illustrated, for example a linear actuator of a rotary type (lead nut and screw, rack and pinion or rod and crank), or an actuator based on other linear systems (for example, a hydraulic or pneumatic cylinder or a linear motor).

[0134] The aforesaid support 120 is optional, in particular when the linear movement of the welding tool 110 along the trajectory D or a generic movement of the welding tool 110 is required, or when indirect mounting of the welding tool 110 on the base 130 is required. Alternatively, the welding tool 110 might be fixed directly to the base 130.

[0135] The welding tool 110, at the front of it, has a first active welding surface

[0136] 111 and a second active welding surface 112 which are intended to come into contact with the at least one web or sheet to be welded, in particular, with different surface regions of the at least one web or sheet to be welded.

[0137] Preferably, each active welding surface 111 112 is planar in shape. However, it might have a different shape, for example, concave or convex. Preferably, also, each active welding surface 111 , 112 has a main direction of extension, and thus has an elongated shape. For example, each welding surface 111 , 112 may have a length / width ratio of between 4 and 20.

[0138] Preferably, each active welding surface 111 , 112 is smooth or substantially smooth. By "substantially smooth" is meant that it is such as to present a smooth aspect on a preponderant part of its surface, provided, if necessary, with local recesses or cavities having a specific, non-welding function.

[0139] Alternatively, each active welding surface 111 , 112 has a relief configuration, in particular defining one or more parallel reliefs or a textured pattern, that is to say, an alternating two-dimensional distribution of reliefs and recesses. The configuration of the active welding surface 111 , 112 is linked to the type of weld to be made.

[0140] Preferably, the welding surfaces 111 , 112 are coplanar with each other.

[0141] In an embodiment, the welding surfaces 111 , 112 are separated from each other, for example, by a recess.

[0142] In a different embodiment, the welding surfaces 111 , 112 are defined by portions of the same uninterrupted surface, for example, adjacent portions. In a different embodiment, the welding surfaces 111 , 112 are incident on each other.

[0143] The countertool block 200 comprises a countertool 210 intended to operate in conjunction with the welding tool 110 (defining a welding unit therewith) so as to make a weld on at least one web or sheet interposed between them.

[0144] The countertool block 200 may also comprise a support 220 (optional), on which the countertool 210 is mounted and a base 230 on which the support 220 or the countertool 210 is mounted. In the embodiment illustrated, the support 220 is coupled to the base 230 by a fixed connection. The support 220 may be provided if the movement of the countertool 210 is such that the countertool 210 moves relative to the support 220, the latter being fixed to the base 230 or coupled to it movably according to a different movement.

[0145] In a variant embodiment, the support 220 of the countertool 210 may be coupled to the base 230 by a sliding guide defining a translational, preferably rectilinear, trajectory D. The trajectory D of the countertool 210 may coincide with the trajectory of the welding tool 110 or it may be different. For this purpose, the support 220 and the base 230 of the countertool 210 may be connected to each other by a guide, in particular a linear sliding guide, for example, a dovetail guide or a bar-sleeve guide. The support 220 is made to slide on the base 230 by an actuator, for example a linear actuator of a rotary type (lead nut and screw, rack and pinion or rod and crank), or an actuator based on other linear systems (for example, a hydraulic or pneumatic cylinder or a linear motor).

[0146] According to the invention, the linear movement along the trajectory D may be applied to welding tool 110, to the countertool 210 or to both.

[0147] In particular, Figure 1 shows a non-operating configuration in which welding tool 110 and countertool 210 are spaced from each other, achieved (not necessarily) by retracting the welding tool 110.

[0148] Figure 3 shows a detail view of the countertool 210.

[0149] The countertool 210 is defined by a base element 21 1 , preferably having an elongated shape and frontally defining a first opposing surface 212, intended to work in conjunction with the first active welding surface 111 of the welding tool 110 to make a first weld on the at least one web or sheet, and a second opposing surface 213, intended to work in conjunction with the second active welding surface 112 of the welding tool 110 to make a second weld on the at least one web or sheet. Preferably, the opposing surfaces 212, 213 are fixed to each other. In particular, they may be made as one with the base element 211 .

[0150] Preferably, the active welding surfaces 111 , 112 are fixed to each other. In particular, they may be made as one with the welding tool 110.

[0151] Preferably, each opposing surface 212, 213 has a planar shape. However, it might have a different shape, for example, concave or convex.

[0152] More preferably, each opposing surface 212, 213 lies in a plane corresponding to the plane the respective active welding surface 111 , 112 lies in so as to apply a substantially uniform compression on the at least one web or sheet disposed between the active welding surface 111 , 112 and the respective opposing surface 212, 213.

[0153] Preferably, also, each opposing surface 212, 213 has a main direction of extension, and thus has an elongated shape. For example, each opposing surface 212, 213 may have a length / width ratio of between 4 and 20.

[0154] Preferably, one or both of the opposing surfaces 212, 213 have a relief configuration, in particular defining one or more parallel reliefs or a textured pattern, that is to say, an alternating two-dimensional distribution of reliefs and recesses. The configuration of the opposing surface 212, 213 is linked to the type of weld to be made.

[0155] In particular, the first opposing surface 212 and the first active welding surface 111 are suitable for forming a first welding configuration (Figure 8) in which they are pressed together at a first welding surface PS1 , while the second opposing surface 213 and the second active welding surface 112 are suitable for forming a second welding configuration (Figures 6 and 9) in which they are pressed together at a second welding surface PS2. Preferably, the welding surfaces PS1 and PS2 are planar.

[0156] Preferably, the welding surfaces PS1 and PS2 are coplanar.

[0157] Alternatively, the welding surfaces PS1 and PS2 might have a different shape, for example, concave or convex.

[0158] The expression "welding surface" is used to mean a surface, whether plane or otherwise configured, extending over the entire contact / overlap area between each active welding surface 111 , 112 and the respective opposing surface 212, 213, hence equal in extent to the contact / overlap area.

[0159] Preferably, the first and the second opposing surfaces are configured to make respective welds which differ in structure and / or kind, being in particular a hermetic weld and a cosmetic weld. In the embodiment illustrated, the first opposing surface 212 makes a hermetic weld, while the second opposing surface 213 makes a cosmetic weld. The hermetic weld defines a hermetic seal while the cosmetic weld defines a coupling between the end flaps of the article obtained by welding the at least one sheet or web. This is particularly advantageous when welding pouches (Figure 2), where the hermetic weld is closer to the contents of the pouch, while the cosmetic weld faces outward, that is to say, is at a position closer to the free edge of the pouch.

[0160] The invention comprises performing a mutual rotation between the welding tool 110 and the countertool 210 about the axis X.

[0161] In the embodiment illustrated, the countertool 210 is rotatable about an axis X, in particular thanks to the base element 21 1 being rotatably mounted on the support 220.

[0162] Preferably, the axis X is substantially coplanar with the welding surfaces PS1 , PS2. By "substantially coplanar" is meant exact coplanarity or a minimum deviation, preferably less than 5%, preferably less than 2% of the length of the welding surfaces PS1 , PS2.

[0163] In the case of a welding surface which is not planar, reference is made to a mean plane intersecting the welding surface PS1 , PS2 at a position such as to be a midplane thereof and to separate the welding surface PS1 , PS2 into portions disposed on opposite sides of the midplane and "balanced" with each other.

[0164] Preferably, the axis X is spaced from the welding surfaces PS1 , PS2.

[0165] Alternatively, the axis X is substantially coplanar with the opposing surfaces 212, 213. By "substantially coplanar" is meant exact coplanarity or a minimum deviation, preferably less than 5%, preferably less than 2% of the length of the opposing surface 212, 213.

[0166] Alternatively, the axis X is spaced from the opposing surfaces 212, 213.

[0167] In the embodiment illustrated, the base element 211 is hinged, at opposite ends of it, to the support 220. For that purpose, the support 220 has the shape of a C defining side walls 221 to which the base element 211 is hinged. Preferably, the side walls 221 are parallel to each other and perpendicular to the axis X.

[0168] Additionally, in order to ensure that the axis X is coplanar or substantially coplanar with at least one of the welding surfaces PS1 , PS2 and / or at least one of the opposing surfaces 212, 213, the base element 211 has, on opposite sides of it, respective protrusions 214 hinged to the support 200 (and in particular to the side walls 221 ) about the axis X. The protrusions 214 protrude in height beyond the opposing surfaces 212, 213 so as to "retract" the base element 211 , positioning the opposing surfaces 212, 213 in proximity to the axis X or in such a way that the axis X is coplanar with at least one of the opposing surfaces 212, 213. In this case, the countertool 210 also has the shape of a C, with concavity, in use, facing the same direction as the concavity of the C shape of the support 220.

[0169] In order to perform a controlled rotation of the countertool 210 about the axis X, relative to the support 220, an actuator 240 is provided which is mounted on the support 220 and interposed between the support 220 and the countertool 210. More in detail, the actuator 240 has one end connected to the support 220, in particular hinged, and another end which is hinged to the countertool 210 at an eccentric position relative to the axis X. Preferably, the actuator 240 is hinged to a flange 215 protruding from the base element 211 , in particular protruding along a direction perpendicular or substantially perpendicular to the direction of extension of the aforesaid protrusions 214 protruding from the base element 211 .

[0170] The actuator 240 is preferably of the lead nut / screw type but, alternatively, it may be a hydraulic or pneumatic cylinder, a linear motor or other technically equivalent solutions.

[0171] In variant embodiments, the mutual rotation between the welding tool 110 and the countertool 210 may be accomplished by mounting the welding tool 110 rotatably, for example on the related support 120, or by mounting both of them rotatably about a common axis X.

[0172] Thanks to the rotation about the axis X, the device 1 can form the two welding configurations which are separated from each other by a simple rotation about the axis X.

[0173] Preferably, thanks to the rotation about the axis X, the device 1 may also form a disengaged configuration (Figures 5 and 7), in which each active welding surface 111 , 112 is spaced from the respective opposing surface 212, 213.

[0174] In particular, starting from a spaced-apart configuration between welding tool 110 and countertool 210 (Figures 1 and 4), a relative movement is performed between welding tool 110 and countertool 210 to draw them closer together, to reach the aforementioned disengaged configuration (Figures 5 and 7). Next, a rotation performed about the axis X by welding tool 110 and / or countertool 210 causes the first active welding surface 111 and the first opposing surface 212 to be pressed against each other, thus making a first weld on the at least one web or sheet interposed between them (Figure 8).

[0175] Next, a further rotation about the axis X in the opposite direction is performed by welding tool 110 and / or countertool 210 causing first active welding surface 111 and first opposing surface 212 to be disengaged and second active welding surface 112 and second opposing surface 213 to be pressed against each other, thus making a second weld on the at least one web or sheet interposed between them (Figure 9).

[0176] In a variant not illustrated, the rotation about the axis X might be defined by an arcuate sliding guide, concentric with the axis X, instead of a pin or hinge connection. Preferably, the first and the second opposing surfaces 212, 213 lie in respective planes making an angle of between 30° and 175°, and still more preferably, between 90° and 170°.

[0177] Alternatively, the angle of between 30° and 175°, and still more preferably, between 90° and 170° is obtained between the first and the second active welding surfaces 111 , 112.

[0178] Figure 10 illustrates a preferred embodiment of the invention in detail.

[0179] According to this solution, the countertool 210 has a distal portion 216 facing towards the welding tool 110 and adapted to define, in cooperation with the welding tool 110, a welding or cutting line or area substantially parallel to the axis X. This welding or cutting action performed by the distal portion 216 is accomplished by applying a predetermined pressure of the distal portion 216 on the welding tool 110.

[0180] Preferably, the distal portion 216 is defined by a protuberance or front corner of the base element 211 and / or of one of the opposing surfaces 212, 213.

[0181] Preferably, the distal portion 216 protrudes from the opposing surfaces 212.

[0182] Preferably, also, the distal portion 216 is interposed between the opposing surfaces 212, 213.

[0183] Preferably, the base element 211 has, at the front of it, a wedge-like shape provided, at the centre, with the aforementioned protruding distal portion 216 and, on opposite sides, with the aforementioned first and second opposing surfaces 212, 213.

[0184] Preferably, the distal portion 216 is substantially parallel to the opposing surfaces 212, 213. By "substantially parallel" is meant a parallelism with an angular tolerance of ±10°.

[0185] Preferably, the distal portion 216 is configured in such a way as to define a weld which is different from the weld made between the active welding surfaces 111 , 112 and the opposing surfaces 212, 213.

[0186] In a variant embodiment, the distal portion is defined on the welding tool 110. In such a case, the distal portion preferably protrudes from the active welding surfaces 111 , 112.

[0187] Additionally, in such a case, the distal portion is preferably parallel or substantially parallel to the active welding surfaces 111 , in particular to their main directions of extension.

[0188] Additionally, also in such a case, the distal portion is preferably interposed between the active welding surfaces 111 , 112.

[0189] Preferably, also in this case, the welding tool 110 has, at the front of it, a wedge-like shape provided, at the centre, with the aforementioned protruding distal portion 216 and, on opposite sides, with the aforementioned first and second active welding surfaces 111 , 112.

[0190] In a variant embodiment, the distal portion may be made on both sides (welding tool 110 and countertool 210) and the two distal portions may operatively cooperate to make a respective weld.

[0191] According to a different aspect of the invention, the countertool 210 has a front protuberance 217 facing towards the welding tool 110, while the welding tool 110 has a corresponding front recess 113 configured to receive at least part of the front protuberance 217.

[0192] Front protuberance 217 and front recess 113 face each other so as to make, in a sheet or web to be welded interposed between welding tool 110 and countertool 210 in a close-together configuration, a local bend (Figure 11 ) suitable for stably holding the sheet or web to be welded in place during the mutual rotation between welding tool 110 and countertool 210, or a cut in a sheet or web to be welded interposed between welding tool 110 and countertool 210 (Figure 12).

[0193] Preferably, front protuberance 217 and front recess 113 have respective main directions of extension parallel to the axis X.

[0194] Preferably, also, the front protuberance 217 is interposed between the opposing surfaces 212, 213.

[0195] Preferably, the front recess 113 is interposed between the active welding surfaces 111 , 112. In a variant embodiment, the front protuberance is made on the welding tool 110 while the front recess is made on the countertool 210.

[0196] In a variant embodiment (Figure 13), the front protuberance and the front recess are disposed respectively on the outside of the opposing surfaces 212, 213 and of the active welding surfaces 111 , 112 so that one of the two active welding surfaces 112 is interposed between the other active welding surface 111 and the front recess 113 and so that one of the two opposing surfaces 213 is interposed between the other opposing surface 212 and the front protuberance 217. Preferably, the front protuberance and the front recess are located at an outside position, facing towards the cosmetic weld, so as to trim the end edge of the web or sheet in the case of welding a pouch.

[0197] The embodiment of Figure 13 shows, specifically, two front protuberances 217 on the countertool 210 and two front recesses 113 on the welding tool 110. A first protuberance-recess pair is located respectively between the first and the second opposing surfaces 212, 213 and between the first and the second active welding surfaces 111 , 112, in particular to hold in place the at least one web or sheet to be welded, while the second protuberance-recess pair is located respectively on the outside of, the second opposing surface 213 and of the second active welding surface 112 to make the cut (outer trimming) in the at least one web or sheet. It is evident, therefore, that according to the invention it is possible for there to be only one recess and only one protuberance at an intermediate position between the active welding surfaces and the opposing surfaces, only one recess and only one protuberance on the outside of the active welding surfaces and opposing surfaces, or two recesses and two protuberances as shown in Figure 13.

[0198] In an embodiment, the front recess 113 is adjacent to the respective active welding surface 112 and the front protuberance 217 is adjacent to the respective opposing surface 213. Alternatively, the front recess 113 is juxtaposed with the respective active welding surface 112 and spaced from it, while the front protuberance 217 is juxtaposed with the respective opposing surface 213 and spaced from it.

[0199] In a different embodiment, the front recess is on the welding tool, while the front protuberance is on the countertool.

[0200] In an embodiment, the tool block 100 and the countertool block 200 are mounted on a conveyor movable along a movement path which is at least partially parallel and / or coplanar with the welding surfaces PS1 , PS2. In this solution, therefore, the welding unit defined by the welding tool 110 and the countertool 210 is movable along the movement path in such a way as to make a seam tracking weld.

[0201] In use, the welding tool 110 and the countertool 210 are positioned in the disengaged configuration (Figures 5, 7), with at least one sheet or web to be welded interposed between the welding surfaces 111 , 112 and the opposing surfaces 212, 213, and then a mutual rotation between the welding tool 110 and the countertool 210 about the axis X is performed in one direction, until reaching the first welding configuration (Figure 8) to make the first weld on the at least one sheet or web, in particular the hermetic weld.

[0202] Next, a mutual rotation between the welding tool 110 and the countertool 210 about the axis X is performed in the opposite direction, until reaching the second welding configuration (Figures 6 and 9) to make the second weld on the at least one sheet or web, in particular the cosmetic weld.

[0203] The second weld comprises simultaneously cutting the at least one web or sheet in the case where the front protuberance 217 on the outside of the second welding surface 213 is provided.

[0204] Preferably, the axis X is kept stationary relative to the welding surfaces PS1 , PS2 at least during part of the mutual rotation between the welding tool 110 and the countertool 210 about the axis X, preferably during the entire rotation about the axis X from the disengaged configuration to the welding configuration.

[0205] The mutual rotation may be accomplished by rotating only the welding tool 110, only the countertool 210, or both.

[0206] Additionally, in order to allow advancing the web or sheet to be welded and / or inserting it into the welding zone and removing it on completion of welding, a relative movement is also performed between the welding tool 110 and the countertool 220 along the aforesaid trajectory D, drawing them towards / away from each other between a close-together configuration, in which the welding tool 110 and the countertool 210 are close together along the trajectory D (Figures 2 and 5-13), and a spacedapart configuration, in which said welding tool 110 and countertool 220 are spaced apart along the trajectory D (Figures 1 and 4).

[0207] Performing the relative movement between the welding tool 110 and the countertool 210 along the trajectory D is carried out by moving only the welding tool 110, only the countertool 210, or both, along the trajectory D. Preferably, the relative movement towards / away is controlled independently of the rotation about the axis X. Preferably, the relative movement towards / away is in any case performed synchronously with the rotation about the axis X so as to optimize the welding process, according to predefined movements in optimal sequences.

[0208] Preferably, the mutual rotation between the welding tool 110 and the countertool 210 about the axis X from the disengaged configuration towards the welding configurations is carried out at least partly after the relative movement which draws the welding tool 110 and the countertool 210 closer together along the trajectory D. Additionally, a movement which spaces the welding tool 110 and the countertool 210 apart along the trajectory D is carried out after reaching the second welding configuration and after completing the welds.

[0209] Additionally, in use, the distal portion 216 of the welding tool 110 and / or of the countertool 210 is pressed against the other between the welding tool 110 and the countertool 210, thereby making a weld along a welding line or area substantially parallel to the axis X. The step of pressing the distal portion 216 is carried out at least partly before mutually rotating the welding tool 110 and the countertool 210 about the axis X towards the first welding configuration.

[0210] In a variant embodiment, the welding tool 110 and the countertool 210 are drawn closer together along the trajectory D until reaching the close- together configuration in which the front protuberance 217 is at least partly inserted into the front recess 113 thereby making a cut in the sheet or web to be welded or a local bend in the sheet or web to be welded, in a manner suitable for stably holding the sheet or web to be welded during the mutual rotation between the welding tool 110 and the countertool 210.

[0211] According to the general nature of the invention, therefore, the device 1 comprises a movement unit configured for performing a controlled relative movement between welding tool 110 and countertool 210. This movement unit comprises, in particular, at least a first movement device configured for performing the mutual rotation between welding tool 110 and countertool 210 about the axis X. The first movement device comprises, in particular, the support 220, to which the countertool 210 is hinged, and the respective actuator 240.

[0212] The movement unit preferably comprises a second movement device configured for performing a relative movement to draw welding tool 110 and countertool 210 towards / away from each along the direction D. The movements are preferably controlled by a control unit, not illustrated, programmed to perform the movements in a presettable, controllable manner as a function of different requirements and / or operating parameters (thickness of material, to be welded, type of material, type of weld, and so on).

[0213] This invention thus achieves the proposed aims. The use of a rotational movement to engage and disengage the welding and opposing surfaces relative to the material to be welded and to switch the device between the two welding configurations achieves great constructional simplicity, great compactness and great robustness.

Claims

CLAIMS1 . A welding device (1 ) for product packaging machines, comprising:- a welding unit (110, 210) comprising a welding tool (110) and a countertool (210) mutually movable relative to each other in rotation about an axis (A), the welding tool (110) defining at least one first active welding surface (111 ) and at least one second active welding surface (112), and the countertool (210) defining at least one first opposing surface (212) and at least one second opposing surface (213),- a movement unit comprising at least one first movement device (220, 240) configured to perform a mutual rotation between said welding tool (100) and said countertool (200) about said axis (A) between a first welding configuration, in which said first active welding surface (111 ) and said first opposing surface (212) are held tightly together at a first welding surface (PS1 ) and said second active welding surface (112) and said second opposing surface (213) are spaced apart, and a second welding configuration, in which said second active welding surface (112) and said second opposing surface (213) are held tightly together at a second welding surface (PS2) and said first active welding surface (111 ) and said first opposing surface (212) are spaced apart.

2. The device according to claim 1 , wherein said at least one first movement device (220, 240) is configured to rotate the welding tool (110) and / or said countertool (210) alternately about said axis (A) between said first and second welding configurations.

3. The device according to claim 1 or 2, wherein said axis (A) is substantially parallel to said first welding surface (PS1 ) and / or to said second welding surface (PS2).

4. The device according to any one of the preceding claims, wherein said first and second opposing surfaces (212, 213) lie in respective planes, said planes preferably making an angle between 30° and 175°, still more preferably between 90° and 170°, and / or said first and second active welding surfaces (111 , 112) lie in respective planes, said planes preferablymaking an angle between 30° and 175°, still more preferably between 90° and 170°.

5. The device according to claim 4, wherein said axis (A) is substantially coplanar with said first and / or with said second welding surface (PS1 , PS2).

6. The device according to claim 4, wherein said axis (A) is spaced from said first and / or said second welding surface (PS1 , PS2).

7. The device according to any one of the preceding claims, wherein said welding unit (2) is configured to make, at said first and second opposing surfaces (212, 213), welds which differ in structure and / or kind, being in particular a hermetic weld and a cosmetic weld.

8. The device according to any one of the preceding claims, wherein said at least one first movement device (220, 240) is also configured to perform a mutual rotation between said welding tool (110) and said countertool (210) about said axis (A) so as to form a disengaged configuration in which said first active welding surface (111 ) is spaced from said first opposing surface (212), and in which said second active welding surface (112) is spaced from said second opposing surface (213).

9. The device according to claim 8, wherein said disengaged configuration is intermediate between said first and second welding configurations, and wherein said first and second welding configurations are defined by opposite rotations of the welding tool (110) and / or of the countertool (210) about said axis (A).

10. The device according to any one of the preceding claims, wherein said axis (A) is kept stationary relative to the welding surfaces (PS1 , PS2) at least during the mutual rotation between the welding tool (110) and the countertool (210) about said axis (A).11 . The device according to any one of the preceding claims, wherein said at least one first movement device (220, 240) comprises a support (220), to which the welding tool (110) and / or the countertool (210) is rotatably connected, in particular by means of a pivot or an arcuate guide, and atleast one actuator (240) for moving said welding tool (110) and / or said countertool (210) in rotation relative to the support (220).

12. The device according to any one of the preceding claims, comprising only one first movement device, operating on the welding tool (110).

13. The device according to any one of claims 1 to 11 , comprising only one first movement device, operating on the countertool (210).

14. The device according to any one of the preceding claims, wherein said movement unit comprises at least one second movement device configured to perform a relative movement between said welding tool (110) and said countertool (210) to draw them towards / away from each other along a trajectory (D) incident on said welding surfaces (PS1 , PS2) between a close-together configuration, in which said welding tool (110) and said countertool (210) are close together along said trajectory (D), and a spaced-apart configuration, in which said welding tool (110) and said countertool (210) are spaced apart along said trajectory (D).

15. The device according to claim 14 when dependent on claim 11 , wherein said at least one second movement device operates on said support (220) to move said support (220) along said trajectory (D).

16. The device according to claim 15, wherein said support (220) is mounted on a guide and wherein said at least one second movement device comprises a respective actuator connected to said support (220) to move said support (220) along said guide.

17. The device according to any one of claims 14 to 16, wherein said trajectory (D) is substantially rectilinear and transverse to said first welding surface (PS1 ) and / or to said second welding surface (PS2) at least in said close-together configuration.

18. The device according to any one of claims 14 to 17, wherein one between said welding tool (110) and said countertool (210) has a distal portion (216) which faces towards the other between said welding tool (110) and said countertool (210) and which is adapted to define, in conjunction with the other between said welding tool (110) and saidcountertool (210), a welding or cutting line or area substantially parallel to said axis (A).

19. The device according to claim 18, wherein said distal portion is defined on the welding tool (110) and is parallel to at least one of said active welding surfaces (111 , 112) or said distal portion (216) is defined on the countertool (210) and is substantially parallel to at least one of said opposing surfaces (212, 213).

20. The device according to claim 18 or 19, wherein said distal portion(216) and / or said other between said welding tool (110) and said countertool (210) is configured in such a way as to define a weld which is different from the weld between each of the active welding surfaces (111 , 112) and the respective opposing surface (212, 213).21 . The device according to any one of claims 18 to 20, wherein said distal portion (216) is interposed between said active welding surfaces (111 , 112) or said opposing surfaces (212, 213).

22. The device according to any one of claims 14 to 17, wherein one between said welding tool (110) and said countertool (210) has a front protuberance (217), facing towards the other between said welding tool (110) and said countertool (210), and wherein the other between said welding tool (110) and said countertool (210) has a front recess (113), said front protuberance (217) and said front recess (113) having respective main directions of extension which are parallel to said axis (A) and facing each other so that, in the close-together configuration, they cut a sheet or web to be welded, interposed between welding tool (110) and countertool (210) or locally bend a sheet or web to be welded, interposed between welding tool (110) and countertool (210), in a manner suitable for stably holding the sheet or web to be welded in place during the mutual rotation between the welding tool (110) and the countertool (210).

23. The device according to claim 22, wherein said front protuberance(217) and said front recess (113) are disposed outside the respective active welding surfaces (111 , 112) or the respective opposing surfaces(212, 213), so that one of the two active welding surfaces (112) is interposed between the other active welding surface (111 ) and the front protuberance (217) or front recess (113) and so that one of the two opposing surfaces (212) is interposed between the other opposing surface (211 ) and the front protuberance (217) or front recess (113).

24. The device according to any one of the preceding claims, wherein said active welding surfaces (111 , 112) are fixed relative to each other and wherein said opposing surfaces (212, 213) are fixed relative to each other.

25. The device according to any one of the preceding claims, further comprising a conveyor movable along a movement path which is at least partially parallel and / or coplanar with the welding surfaces (PS1 , PS2), wherein the welding unit (110, 210) and the movement unit are mounted on the conveyor and are movable along the movement path in such a way as to make a seam tracking weld.

26. The device according to any one of the preceding claims, wherein said welding tool (110) is an ultrasonic welding tool.

27. A welding method for product packaging machines, implemented by a device comprising a welding tool (110) and a countertool (210) positioned to face each other, wherein said welding tool (110) defines at least a first active welding surface (111 ) and a second active welding surface (112), and said countertool (210) defines at least a first opposing surface (212) and a second opposing surface (213), and wherein said welding tool (110) and said countertool (210) are configured to form a first welding configuration, in which said first active welding surface (111 ) and said first opposing surface (212) are held tightly together at a first welding surface (PS1 ) and said second active welding surface (112) and said second opposing surface (213) are spaced apart, and a second welding configuration, in which said second active welding surface (112) and said second opposing surface (213) are held tightly together at a second welding surface (PS2) and said first active welding surface (111 ) and said first opposing surface (212) are spaced apart, said method beingpreferably implemented by a device according to any one of the preceding claims, and wherein said method comprises:- positioning said welding tool (110) and said countertool (210) to face each other, with at least one sheet or web to be welded interposed between said active welding surfaces (111 , 112) and said opposing surfaces (212, 213);- mutually positioning the welding tool (110) and the countertool (210) in the first welding configuration so as to make a first weld on the sheet or web at the first welding surface (PS1 );- mutually rotating said welding tool (110) and said countertool (210) about an axis (A) until reaching said second welding configuration, to make a second weld on said sheet or web at the second welding surface (PS2).

28. The method according to claim 27, wherein said first and second welds differ in structure and / or kind, being in particular a hermetic weld and a cosmetic weld.

29. The method according to claim 27 or 28, wherein said welding tool (110) and said countertool (210) are also configured to form a disengaged configuration where said first active welding surface (111 ) is spaced from the first opposing surface (212) and where said second active welding surface (112) is spaced from said second opposing surface (213), and wherein said method further comprises positioning said welding tool (100) and said countertool (200) at the second disengaged position before reaching the first welding configuration and / or after reaching the second welding configuration.

30. The method according to claim 29, wherein said disengaged configuration is intermediate between said first and second welding configurations, and wherein said first and second welding configurations are defined by opposite rotations of the welding tool (100) and / or of the countertool (200) about the axis (A) relative to the disengaged configuration.31 . The method according to any one of claims 27 to 30, wherein said axis(A) is kept stationary relative to the sheet or web to be welded at least during the mutual rotation between the welding tool (110) and the countertool (210) about said axis (A).

32. The method according to any one of claims 27 to 31 , wherein mutually rotating the welding tool (110) and the countertool (210) is carried out by rotating only the welding tool (110) or only the countertool (210).

33. The method according to any one of claims 27 to 32, further comprising performing a relative movement between said welding tool (110) and / or said countertool (210) to draw them towards / away from each other along a trajectory (D) incident on said welding surfaces (PS1 , PS2) between a close-together configuration, in which said welding tool (110) and said countertool (210) are close together along the trajectory (D), and a spaced-apart configuration, in which said welding tool (110) and said countertool (210) are spaced apart along the trajectory (D).

34. The method according to claim 33, wherein mutually moving the welding tool (110) and / or the countertool (210) along the trajectory (D) is carried out by moving only the welding tool (110) or only the countertool (210) along the trajectory (D).

35. The method according to claim 33 or 34, wherein performing a relative movement between the welding tool (110) and / or the countertool (210) along the trajectory (D) comprises a relative movement between the welding tool (110) and the countertool (210) to draw them towards each other along the trajectory (D) at least partly before mutually positioning the welding tool (110) and the countertool (210) in the first and / or the second welding configuration, in particular while the welding tool (110) and the countertool (210) are angularly positioned relative to each other in an intermediate configuration between said first and second welding configurations, in particular said disengaged configuration, and further comprises performing a relative movement between the welding tool (110) and the countertool (210) to draw them away from each other along the trajectory (D) after reaching said first and second welding configurations.

36. The method according to any one of claims 33 to 35, wherein performing a relative movement between the welding tool (110) and the countertool (210) to draw them towards each other along the trajectory (D) comprises pressing a distal portion (216) on one between said welding tool (110) and said countertool (210) against the other between said welding tool (110) and said countertool (210), thus making a weld along a welding line or area substantially parallel to said axis (A), said pressing of the distal portion (216) being carried out at least partially while the welding tool (110) and the countertool (210) are angularly positioned relative to each other in the intermediate configuration.

37. The method according to claim 36, wherein the weld made between said distal portion (216) and said other between said welding tool (110) and said countertool (210) is different from the welds made between each active welding surface (111 , 112) and the respective opposing surface (212, 213).

38. The method according to any one of claims 33 to 35, wherein one between said welding tool (110) and said countertool (210) has a front protuberance (217), facing towards the other between the welding tool (110) and the countertool (210), and wherein said other between said welding tool (110) and said countertool (210) has a front recess (113), said front protuberance (217) and said front recess (113) having respective main directions of extension which are parallel to the axis (A) and facing each other, and wherein said relative movement between the welding tool (110) and countertool (210 to draw them towards each other along the trajectory (D) makes, in the close-together configuration, a cut in at least one sheet or web to be welded between the welding tool (100) and the countertool (200), and / or a local bend in at least one sheet or web to be welded, in a manner suitable for stably holding said at least one sheet or web to be welded during the mutual rotation between the welding tool (100) and the countertool (200).

39. The method according to any one of claims 27 to 38, furthercomprising moving the welding unit (110, 210) and the movement unit along a movement path, where mutually rotating the welding tool (110) and the countertool (210) about the axis (A) is carried out during said moving of the welding unit (110, 210) and the movement unit along the movement path in such a way as to make a seam tracking weld.

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