Welding device and method for product packaging machines

Abstract

A welding device (1) for product packaging machines, comprising a rotating conveyor (100) on which mounting members (400) are mounted, the mounting members being movable about an axis (X) and each carrying a respective welding unit (200), wherein the conveyor (100) comprises, for each mounting member (400), a respective conveying mechanism (300) configured to vary the position of the mounting member (400) according to three degrees of freedom during the movement of the mounting member (400) about the axis (X) so as to define a rectilinear, tracking movement of the welding units (200) in the welding zone (Z).

Description

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

[0002] Field of the art

[0003] The present invention relates to the technical field of automatic product packaging machines and relates, in detail, to a device and method for product packaging machines, in particular for transversely welding on a continuous wrapper.

[0004] Background art

[0005] Such devices are generally used in product packaging machines in many industries, e.g., pharmaceutical, food, or cosmetics. It is known that automatic product packaging machines used in such industries must perform processes on products under conditions of high-quality precision. Moreover, it is known that automatic product packaging machines must ensure high productivity in terms of quantity.

[0006] Machines dedicated to the aforementioned areas comprise a welding device configured to weld and preferably cut a web so as to obtain a plurality of packages each containing one or more items wrapped in a sometimes hermetic package.

[0007] Structurally, the known welding devices comprise a feeding system for feeding a sequence of items to be packaged, a forming unit for forming a continuous tubular tube enclosing the items, a longitudinal welding unit for making a weld in the direction of feeding the tubular tube, and a transverse welding unit for making transverse welds on the continuous tubular tube so as to completely enclose the items.

[0008] In particular, in a known embodiment of the "tracking" type, the transverse welding unit comprises a welding tool and a tool anvil defining a transverse welding line and movable along circular and coplanar trajectories tangent to each other in the welding zone of the web. This can be achieved, for example, by mounting the cutting tool and tool anvil on respective wheels having parallel axes and parallel to the welding line (e.g., known from application W02007 / 012917) or on articulated linkages movable along coplanar circular trajectories. The tool and tool anvil are moved in a manner synchronized with each other so as to cyclically define at least one disengaged configuration, in which the tool and tool anvil are moved apart, and one welding configuration, in which the tool and tool anvil abut for welding and, where applicable, also for cutting the web.

[0009] Systems are also known for the transverse movement of the welding tool and the tool anvil, in particular along a reciprocal motion direction towards and away from each other perpendicular to the welding line. Such solutions involve, for example, respective carriages translating along a common translation line perpendicular to the welding line to obtain the disengaged configuration, in which the tool and the tool anvil are moved apart, and the welding configuration, in which the tool and tool anvil abut for welding, but with the need to stop the feeding of the web during the welding. The web thus must have an intermittent feeding speed.

[0010] Object of the invention

[0011] The Applicant has observed that, even in their most modern implementations, the systems described above have some drawbacks.

[0012] The Applicant has observed that the web welding process requires a minimum welding time for the tool and the tool anvil to complete the welding of the web correctly (this applies also in the case of the use of ultrasonic welders and in the case of use of thermal welders). Such a time is long in the case of particularly critical welds or of the hermetic type.

[0013] The Applicant has also observed that the most modern packaging machines have very high speeds that have very short item transit times, which hinder correct performance of the welding.

[0014] The Applicant has observed that, in the case of rotary systems, since the abutment of the welding means occurs limited to the point of tangency between the circular trajectories of the welding tool and the tool anvil, and since the welding time is set by technical specifications also related to design parameters (weld geometry, materials, etc.), it is necessary to limit the processing speed to the detriment of productivity in order to ensure a qualitatively correct welding of the web.

[0015] The Applicant has observed that in the case of stationary systems, with the welding tool and tool anvil movable only by reciprocal motion towards and away from each other instead, there is the additional constraint of the stopping time of the web during welding, which greatly reduces the production speed.

[0016] The Applicant has further observed that, in the case of rotary systems or otherwise closed path systems, there is the problem of ensuring the correct performance of the welding because the welding tool and the tool anvil must remain mutually pressed for a minimum time needed to complete the welding. Disadvantageously, such a minimum time requires the adoption of complex trajectories which impose high complexity and size of the conveyors used to support the welding tool and the tool anvil.

[0017] The Applicant has thus realized that mounting the welding tool and the tool anvil on a movable mounting member along a closed conveying path which extends about an axis and varying the position of the mounting member according to three degrees of freedom during the movement of the mounting member about the axis, so that the conveying path has at least one rectilinear stretch parallel to the direction of feeding of the material being welded at least in the welding zone, allow reducing or eliminating the difficulties of synchronization and calibration present in the devices of the prior art.

[0018] Indeed, the Applicant has found that a continuous and high-precision adjustment of the welding tool and the tool anvil can be performed in this manner, even using conveyors of simple structure, such as rotary or closed-loop conveyors, for example. In particular, the Applicant has observed that, in the case of rotary conveyors with a conveying path having a rectilinear stretch in the welding zone, two of the three degrees of freedom can be the distance of the mounting member with respect to the rotation axis and the oscillation of the mounting member about an axis of oscillation parallel to the rotation axis, while the third degree of freedom can be the position of the welding tool and the tool anvil along the rectilinear movement direction in the welding zone. Tracking welds can thus be achieved with high-precision in positioning the welding tool and the tool anvil even in the case of rotary conveyors without modifying the feeding speed of the web or stopping it, creating a condition of substantially zero relative speed between the welding unit and the web in the direction of feeding of the web.

[0019] Therefore, the present invention relates, in a first aspect thereof, to a welding device for product packaging machines.

[0020] Preferably, the device comprises guide means configured to feed at least one web to be welded along a first direction through a welding zone.

[0021] Preferably, the device further comprises at least one conveyor.

[0022] Preferably, the conveyor defines a closed conveying path which extends about an axis.

[0023] Preferably, such a closed conveying path passes through the welding zone.

[0024] Preferably, the device comprises at least one movable mounting member along the closed conveying path.

[0025] Preferably, the device comprises at least one welding unit configured to transversely weld the web.

[0026] Preferably, each welding unit comprises a welding tool and a respective tool anvil.

[0027] Preferably, the welding unit is mounted on at least one mounting member to track the closed conveying path. In other words, the conveyor moves the welding unit along the closed conveying path. Preferably, the conveyor determines the law of motion of the welding unit along the closed conveying path.

[0028] Preferably, the welding unit and the respective tool anvil of each welding unit move along respective trajectories mutually synchronized along the closed conveying path.

[0029] Preferably, the trajectories are closed trajectories.

[0030] Preferably, the welding tool and the respective tool anvil of the same welding unit are further movable according to a reciprocal motion towards and away from each other along a second direction.

[0031] Preferably, the conveyor comprises an active conveying mechanism acting on the at least one mounting member and configured to vary the position of the at least one mounting member according to three degrees of freedom as the mounting member moves about the axis so that the conveying path has at least one rectilinear stretch parallel to the first direction at least in the welding zone.

[0032] The term "active" means, within the scope of the present invention, a conveying mechanism which acts on the at least one mounting member by means of a respective actuation so as to cause a movement (according to three degrees of freedom) with respect to the conveyor.

[0033] The present invention relates, in a second aspect, to a welding method.

[0034] Preferably, such a welding method forms part of a product packaging process, preferably of the flowpack type.

[0035] Preferably, such a method either is or can be operated by a device according to the aforesaid aspect.

[0036] Preferably, the method includes feeding at least one continuous web along a first direction through a welding zone.

[0037] Preferably, the method further includes moving at least one welding unit along a closed conveying path passing through the welding zone and extending about an axis.

[0038] Preferably, the at least one welding unit is configured to transversely weld the web. Preferably, the welding unit comprises a welding tool and a respective tool anvil movable by reciprocal motion towards and away from each other along the second direction.

[0039] Preferably, the movement of the at least one welding unit along the closed conveying path is performed by moving the welding tool and the respective tool anvil along respective closed trajectories passing through the welding zone.

[0040] Preferably, while moving the at least one welding unit along the closed conveying path, the method includes also moving the welding tool and / or the respective tool anvil along the second direction so as to grip and compress at least one portion of the web to make at least one transverse weld.

[0041] Preferably, the at least one welding unit is mounted on a respective mounting member.

[0042] Preferably, moving the at least one welding unit along the closed conveying path comprises actively moving the mounting member about the axis and further comprises, in at least part of the closed conveying path, varying the position of the at least one mounting member according to three degrees of freedom with respect to the closed path so that the conveying path has at least one rectilinear stretch parallel to the first direction at least in the welding zone.

[0043] The term "actively" means, within the scope of the present invention, acting on the at least one mounting member by means of a respective actuation so as to cause the aforesaid movement according to three degrees of freedom.

[0044] The Applicant has found that by operating such a variation of the position of the at least one mounting member according to three degrees of freedom, it is possible not only to obtain a rectilinear movement of the mounting member, and thus of the welding tool and the tool anvil, in the welding zone, but it is also possible to locally adapt the feeding speed of the mounting member along the first direction to the instantaneous speed of the web being welded, even with the use of rotary or otherwise closed- loop conveyors, correcting possible speed discrepancies between the mounting member and the web, which could lead to deformations or breakages of the web or to non-conforming welds.

[0045] In at least one of the above aspects, the present invention can also have at least one of the preferred features set forth below.

[0046] Preferably, the conveying mechanism is configured to vary:

[0047] - the distance of each mounting member from the axis,

[0048] - the angle of each mounting member about a respective axis of oscillation, preferably parallel to the second direction and / or to the axis, and

[0049] - the position of the mounting member along a direction tangential to the closed conveying path and / or along the first direction in the welding zone.

[0050] By virtue of the three degrees of freedom, and in particular of the tangential degree of freedom, a movement of the welding unit is obtained, perfectly synchronizable with the web in the welding zone, in particular at least for the dwell time of the welding unit in a gripped configuration on the web, independently of the configuration of the conveyor.

[0051] Preferably, each mounting member has rectilinear translation movement and more preferably uniform at the welding zone. This is adapted to a rectilinear and uniform feeding of the web in the welding zone.

[0052] Preferably, the axis of oscillation is fixed with respect to the mounting member, for example defined by one or more hinges integral with the mounting member.

[0053] Preferably, the angle of each mounting member is varied by rotating (oscillating) the mounting member about a respective axis of oscillation. Such an oscillation occurs for a predetermined angle less than 360°, preferably less than 180°, and even more preferably less than 120°.

[0054] Preferably, the variation of the position of the at least one mounting member according to the three degrees of freedom during the movement of the mounting member is periodic, i.e., cyclically repeated back and forth for each travel on the closed conveying path. This is compatible with the periodic movement of the welding units which alternate gripping (welding) intervals with rest intervals (transfer movement).

[0055] Preferably, the variation of the position of the at least one mounting member according to the three degrees of freedom during the movement of the mounting member is predetermined and defined by the geometry of the conveying path set for the mounting member.

[0056] In other words, the mentioned variation of the position of the at least one mounting member according to the three degrees of freedom during the movement of the mounting member is implemented to set a specific and predetermined periodic motion law of the mounting member during the movement along the closed conveying path.

[0057] Preferably, the closed path is defined by a base path, corresponding to the base movement of the conveyor (e.g., a rotation movement which defines a circular base path), added to a variation movement defined by the mentioned variation of the position of the mounting member according to the three degrees of freedom.

[0058] Preferably, the mentioned variation of the position of the at least one mounting member according to the three degrees of freedom is implemented by means of three respective actuation movements about three axes, in particular, three mutually independent actuation movements. This results in a highly flexible adjustment.

[0059] Preferably, the actuation movements are rotation movements about the mentioned axes. This results in a convenient and simple actuation, operable by compact rotary actuators.

[0060] Preferably, the three axes are mutually parallel.

[0061] More preferably, two of the three axes are mutually coincident, the third being parallel and offset with respect to the other two. This results in a compact layout with optimization of the dimensions.

[0062] Preferably, the conveying mechanism comprises at least one articulated linkage having two degrees of freedom and connected to the mounting member rotatably about the axis of oscillation so as to set the position of the axis of oscillation, in particular the position of the axis of oscillation in a plane preferably perpendicular to the axis of oscillation (so that the axis of oscillation always has the same spatial orientation).

[0063] The articulated linkage is preferably in the form of an articulated quadrilateral or pentalateral linkage, comprising in particular four arms hinged to one another where the two end arms are hinged about respective axes fixed with respect to the conveyor.

[0064] Moreover, preferably, the conveying mechanism further comprises at least one auxiliary linkage connected to the mounting member in an eccentric position with respect to the axis of oscillation to cause a rotation of the mounting member about the axis of oscillation.

[0065] In an embodiment, the auxiliary linkage is connected to the mounting member in an eccentric position with respect to the axis of oscillation to cause a rotation of the mounting member about the axis of oscillation.

[0066] In a different embodiment, the auxiliary linkage is connected to the mounting member in a position coaxial to the axis of oscillation, e.g., by means of a bushing or other transmission member rotatable about the axis of oscillation or by means of a rotary motor rotatable about the axis of oscillation.

[0067] Preferably, the articulated linkage comprises a first rotary lever and a second rotary lever, both defining respective arms of the articulated linkage and preferably actuatable in an independent manner. The first rotary lever is rotatable about the first axis of the three actuation axes, and the second rotary lever is rotatable about the second axis of the three actuation axes.

[0068] Preferably, the first and second rotary levers are mounted coaxially with each other.

[0069] Preferably, the two rotary levers define the end arms of the pentalateral linkage, which are hinged about a common rotation axis defining an articulated quadrilateral in this embodiment. According to constructional variants, the two rotary levers define the end arms of the pentalateral linkage, which are hinged about respective rotation axes (fixed with respect to the conveyor), parallel and spaced apart from each other.

[0070] Preferably, the auxiliary linkage comprises a third rotary lever, rotatable about the third of the three actuation axes.

[0071] Preferably, the third rotary lever is connected to the mounting member by means of a link rod, in particular in an eccentric position with respect to the axis of oscillation and by means of a hinge connection.

[0072] Preferably, the third rotary lever is mounted eccentrically with respect to the first and second rotary levers.

[0073] Preferably, the conveying mechanism comprises three independent actuators for each mounting member, each actuator being configured to adjust a respective one of the three degrees of freedom.

[0074] Preferably, the three actuators are connected to the first rotary lever, the second rotary lever, and the third rotary lever, respectively.

[0075] Preferably, each actuator comprises a rotary servomotor, preferably a brushless motor.

[0076] Preferably, each rotary servomotor is arranged with its rotation axis parallel to the axis of the conveyor and / or to the axis of oscillation.

[0077] Preferably, a first actuator is active on the first rotary lever and is arranged coaxially to the first of the three actuation axes, thus coaxially to the first rotary lever.

[0078] Preferably, a second actuator is active on the second rotary lever and is arranged with its axis parallel and offset with respect to the second of the three actuation axes, thus coaxially to the first rotary lever.

[0079] Preferably, the third actuator is active on the third rotary lever and is arranged coaxially to the third of the three actuation axes, thus coaxially to the third rotary lever.

[0080] Preferably, the conveying mechanism comprises a first and a second articulated linkage, where the first articulated linkage is connected to a first end of the mounting member while the second articulated linkage is connected to a second end of the mounting member, opposite to the first end, where the first and second ends of the mounting member are opposed to each other, in particular with respect to the respective welding unit 200. More in particular, the first end of the mounting member is the upper end of the mounting member while the second end of the mounting member is the lower end. Such ends are arranged opposed to each other with respect to the rectilinear stretch of the conveying path in the welding zone.

[0081] Preferably, the conveying mechanism further comprises a first and a second auxiliary linkage, where the first auxiliary linkage is connected to the first end of the mounting member while the second auxiliary linkage is connected to the second end of the mounting member.

[0082] Preferably, the first and second articulated linkages are synchronously movable, preferably being connected to each other so as to operate the same movement of the mounting member.

[0083] Preferably, the first rotary lever of the first articulated linkage and the first rotary lever of the second articulated linkage are mutually coaxial and rigidly connected at least in a rotation movement about the first axis, in particular by means of a first connection shaft.

[0084] Preferably, the second rotary lever of the first articulated linkage and the second rotary lever of the second articulated linkage are mutually coaxial and rigidly connected at least in a rotation movement about the second axis, in particular by means of a second connection shaft.

[0085] Preferably, the first and second shafts are mutually coaxial and rotationally independent, one of the two being a hollow shaft and the other being inserted therein.

[0086] Preferably, the first and second auxiliary linkages are synchronously movable, preferably being connected to each other so as to operate the same movement of the mounting member. Preferably, the third rotary lever of the first auxiliary linkage and the third rotary lever of the second auxiliary linkage are coaxial with each other and rigidly connected at least in a rotation movement about the third axis, in particular by means of a third connection shaft.

[0087] Preferably, the third connection shaft is parallel to the first and second shafts and spaced apart therefrom.

[0088] Preferably, the conveyor comprises a first and a second wall parallel and opposed to each other and transverse to the axis about which the conveying path extends, preferably perpendicular to the axis.

[0089] In an embodiment, at least one of the two walls, preferably both, has a preferably circular, plate-like shape.

[0090] Preferably, the conveying mechanism is arranged in a region enclosed between the two walls.

[0091] Preferably, in greater detail, each conveying mechanism is mounted on the two walls, in particular (exclusively) supported by the two walls.

[0092] Preferably, the walls have holes for the insertion of the first, second, and third shafts for each mounting member.

[0093] Preferably, two of the actuators, and more preferably the actuators associated with the first and second actuation axes or shafts, are mounted on the first wall, and the third actuator is mounted on the second wall.

[0094] Preferably, the conveyor comprises a plurality of mounting members distributed in sequence along the conveying path and / or about the axis, and a plurality of conveying mechanisms each associated with a respective mounting member to adjust the position of the respective mounting member according to three degrees of freedom during the movement of the mounting member along the closed path.

[0095] Preferably, said conveying mechanisms are operable independently of one another, in particular by means of respective actuators controllable independently, in particular electronically.

[0096] Preferably, the closed conveying path lies in a flat positioning plane. Preferably, the axis about which the closed conveying path extends is perpendicular to the positioning plane of the closed conveying path.

[0097] Preferably, the conveyor comprises a rotating conveyor that rotates about such an axis.

[0098] The Applicant has found that this feature allows further simplifying the machine structure, and in particular the welding device, to the benefit of qualitative accuracy and production efficiency as well as the construction and / or maintenance costs of the machine.

[0099] Preferably, the welding unit is configured to make a transverse weld of the web.

[0100] Preferably, the term "transverse weld" means a weld oriented transversely to the main extension direction of the web, thus transversely to the first direction. The term "transverse" is to be understood in the general meaning of inclined or non-parallel, not necessarily rectilinear (e.g., with a broken line weld profile, zig-zag, wavy, etc.). Thus, in general, the transverse welding of the web occurs along at least one welding area (single area or plurality of areas) having main extension direction transverse to the web.

[0101] Preferably, the such a main extension direction of the welding area is rectilinear.

[0102] Preferably, such a main extension direction of the welding area extension is perpendicular to the main extension direction of the web.

[0103] Preferably, the guide means of the web comprise supporting and / or sliding planes, e.g., provided at least in part with rolling or movable tracking members with cyclic motion, configured to support at least one web having a flat positioning. More in general, the guide means preferably define a guiding plane, e.g., a horizontal positioning plane.

[0104] The web can be a single web, e.g., tubular in shape possibly already provided with a continuous longitudinal weld, or a laminate of two or more webs, e.g., connected to each other by one or more continuous longitudinal welds, or a laminate of two or more webs not connected by longitudinal welds.

[0105] Moreover, the guide means can also be configured to feed a sequence of products spaced apart along the direction of feeding.

[0106] Preferably, the guide means comprise a forming unit of a tubular casing by wrapping a web about the products (possibly also about a conveying surface and / or lower product support) and longitudinal welding. The longitudinal welding is preferably performed below the guiding plane.

[0107] In an embodiment, the closed path is substantially circular.

[0108] "Substantially" means, in all occurrences in which it is expressed, a match of 80% or more except where otherwise provided.

[0109] Preferably, the closed path has a substantially circular shape in a stretch corresponding to at least 70% of its extension, preferably at least 80%.

[0110] Moreover, the terms "parallel" and "perpendicular," also in the claims, are to be understood as "substantially parallel" and "substantially perpendicular," respectively, thus to be interpreted with the same tolerance range (±20%).

[0111] In a different embodiment, the closed path has a general shape which is not necessarily circular. In such a situation, the conveyor is configured to define a general non-circular closed conveying path which extends about such an axis. Such an axis is not necessarily the axis of a physical component of the conveyor, but the conveyor can have a rotation axis (e.g., of rotation of an idler member) and extend about such an axis.

[0112] Preferably, the closed path comprises at least one rectilinear stretch arranged and / or passing through the welding zone.

[0113] Preferably, the second direction is transverse to the main extension direction of the welding area defined by the same welding unit.

[0114] Preferably, the second direction is perpendicular to the main extension direction of the welding area defined by the same welding unit.

[0115] Preferably, the tool and the tool anvil are movable by reciprocal motion along the second direction so as to define at least one disengaged configuration, in which the welding tool and the respective tool anvil are spaced away from each other, and a gripping configuration, suitable for transversely welding the web, in which the welding tool and the respective tool anvil are mutually gripped at the welding area.

[0116] Preferably, the closed trajectories of the welding tool and respective tool anvil overlap each other at least in a respective stretch passing through the welding zone. The term "overlap" means an overlap along a direction substantially perpendicular to the positioning of such trajectories.

[0117] Preferably, the closed trajectories of the welding tool and respective tool anvil are substantially identical or symmetrical to each other at least in a respective stretch passing through the welding zone.

[0118] "Substantially" in this case means a match on a main stretch of the trajectory extension, in particular equal to or greater than at least 50% and preferably equal to or greater than 60%. Indeed, the trajectories are defined by a combined movement of the unit along the closed conveying path and a reciprocal motion between the welding tool and the respective tool anvil of the same welding unit along the second direction. Preferably, this movement along the second direction is the only relative movement between the welding tool and the respective tool anvil and preferably concerns only part of the respective trajectories, preferably a stretch equal to or smaller than 50% or equal to or smaller than 40%.

[0119] Moreover, the term "symmetrical" refers to a specular geometry of the trajectories which takes into account the movement of the welding tool and the respective tool anvil along the second direction. Such a feature of being symmetrical is related to the preferably simultaneous, reciprocal motion towards and away from each other of the welding tool and the respective tool anvil along the second direction. The expression "substantially symmetrical" refers to the possibility that the two trajectories differ in terms of being symmetrical in minute parts due, for example, to different values or travel speeds of the welding tool and the respective tool anvil along the second direction. Indeed, the tool anvil preferably has an extra travel not necessarily provided for the welding tool and preferably related to a cutting action of the web in the welding area.

[0120] The Applicant found that this technical feature further simplifies the structure of the product packaging machine, and in particular the welding device. Such a structural simplification allows an optimal synchronization between the tool and the tool anvil, effectively improving operational reliability as well as the qualitative accuracy of the finished product. Moreover, such a structural simplification allows reducing the construction and / or maintenance costs of the machine itself.

[0121] Preferably, the axis about which the closed conveying path extends is transverse to the first direction. Preferably, the axis is perpendicular to the first direction.

[0122] Preferably said guide means are configured to arrange the at least one web lying in a flat positioning plane in the welding zone.

[0123] Preferably, the axis is perpendicular to the positioning plane of at least one web in the welding zone.

[0124] Preferably, in other words, the continuous web lies in a flat positioning plane at least in the welding zone and the movement of the at least one welding unit along the closed conveying path is performed by moving the at least one welding unit about an axis that is transverse, preferably perpendicular, to the flat positioning plane of the web in the welding zone, so that the closed trajectories followed by the welding tool and the respective tool anvil are arranged about such an axis.

[0125] The Applicant has found that this feature provides an optimal layout in terms of process, because the movement of the units can take place coplanar to the web positioning plane in the welding zone.

[0126] Preferably, the second direction is parallel to the rotation axis of the rotating conveyor.

[0127] Preferably, the second direction has a substantially constant orientation during the movement of the welding unit along the closed conveying path. Preferably, in other words, the second direction has constant orientation with respect to the first direction and / or with respect to the axis of the conveyor.

[0128] Preferably, the first direction is rectilinear at least in the welding zone, in particular for at least one linear stretch arranged and / or passing through the welding zone.

[0129] Preferably, the second direction is rectilinear.

[0130] Preferably, the second direction is transverse to the first direction at least in the welding zone.

[0131] Preferably, the second direction is perpendicular to the first direction at least in the welding zone.

[0132] Preferably, the movement of the at least one welding unit along the closed conveying path is performed by simultaneously moving the welding tool and the respective tool anvil of the at least one welding unit along respective trajectories mutually synchronized along the closed conveying path.

[0133] The Applicant found that this feature eliminates any need for synchronization in the movements of the welding tool and the respective tool anvil along the respective trajectories because they are integral with each other in their movement along the closed path.

[0134] Preferably, the mounting member has a preferably monolithic, more preferably plate-shaped, rigid structure.

[0135] Preferably, each mounting member comprises a respective movement mechanism configured to move the welding tool and the respective tool anvil of the respective welding unit reciprocally along the second direction. In a constructional solution, the movement mechanism is configured to move only the welding tool or the tool anvil along the second direction.

[0136] In a different constructional solution, the movement mechanism is configured to move both the welding tool and the respective tool anvil along the second direction. Preferably, the mounting member has a preferably flat partition wall, adapted to separate an operation zone, housing the at least one movement mechanism, from a processing zone, opposite to the operation zone and housing the at least one welding unit.

[0137] The Applicant has found that such a technical feature ensures to perform processes on the products under highly hygienic or even aseptic conditions, in particular to avoid as much as possible any type of contamination of the processed products by lubricating agents or other substances related to the correct operation of the movement mechanism. Preferably, the partition wall has transverse positioning, preferably perpendicular, to the main direction of the welding area.

[0138] Preferably, the mounting member has a closed box shape having an internal space delimiting the operation zone and configured to house at least partially the movement mechanism.

[0139] Preferably, the box-shaped mounting member frontally defines the aforesaid partition wall.

[0140] Preferably, the mounting member comprises one or more dynamic hermetic gaskets arranged to hermetically seal the internal space.

[0141] The term "hermetic" means gaskets capable, when interposed between two environments, of isolating such environments from one another. Preferably, such hermetic gaskets are configured to prevent the passage of dust, or of fluids or liquids (e.g., in the form of airborne droplets or vapors), in particular used for lubrication of the movement mechanism housed inside the mounting member.

[0142] The term "dynamic" refers to the fact that hermetic gaskets are applied to moving members whose geometry and / or position and / or spatial orientation is variable during operation.

[0143] The Applicant found that such a feature allows processing products under conditions of maximum hygiene and environmental control, preventing contamination by substances not pertaining to the food industry. Preferably, the dynamic hermetic gaskets are interposed between the respective welding unit and the respective movement mechanism.

[0144] Preferably, the dynamic hermetic gaskets are interposed on the partition wall.

[0145] Preferably, the at least one movement mechanism crosses the partition wall at at least one opening so that it is connected to the at least one welding unit.

[0146] Preferably, the at least one opening is associated with at least one respective dynamic hermetic gasket so that the internal space is hermetically isolated from the outside.

[0147] Alternatively, the at least one opening is associated with at least one respective non-hermetic, dynamic hermetic gasket.

[0148] Preferably, the at least one opening has a circular profile.

[0149] Preferably, where present, the dynamic hermetic gaskets comprise a first disc, rotatably inserted into the opening and rotatable with respect to said partition wall. Preferably, the first disc comprises, in turn, at least one hole with a circular profile, eccentric to the center of the first disc.

[0150] Preferably, where present, the dynamic hermetic gaskets further comprise a second disc, inserted into the hole of the first disc and rotatable with respect to the first disc. Preferably, the second disc comprises, in turn, a circular hole, eccentric to the center of the second disc; preferably, the hole of the second disc is crossed by a shaft-like portion of the movement mechanism.

[0151] Preferably, the partition wall, the first disc, the second disc and the shaftlike portion are connected to each other by hermetically sealed sliding couplings.

[0152] Preferably, the at least one movement mechanism crosses the partition wall at at least two openings so as to be connected to the welding tool and to the respective tool anvil of the welding unit.

[0153] Preferably, for at least either the welding tool or the respective tool anvil, the movement mechanism comprises a guide, a carriage and an actuator. Preferably, the guide is linear and parallel to the second direction.

[0154] Preferably, the carriage is mounted on the guide in a sliding manner.

[0155] Preferably, the carriage is also connected to the welding tool or respective tool anvil.

[0156] Preferably, the mentioned shaft-like portion is integral with the carriage.

[0157] Preferably, the actuator is connected to the carriage to move the carriage with a controlled to-and-fro movement along the guide.

[0158] Preferably, the actuator comprises an electric motor and a mechanical transmission, preferably a crank mechanism.

[0159] According to a different embodiment, the movement mechanism is configured to move the shaft-like portion of the movement mechanism along a rectilinear trajectory and to impart to the first disc and to the second disc movements which are controllable independently.

[0160] Preferably, the conveyor is configured so that the closed trajectories followed by each welding tool and by the respective tool anvil have at least one rectilinear stretch which passes through the welding zone and which is particularly parallel to the first direction at least in the welding zone.

[0161] The Applicant has found that this feature allows obtaining a tracking motion of the welding tool and respective tool anvil with respect to the web in the welding zone, ensuring the optimal contact time to perform the transverse welding according to preset parameters.

[0162] Preferably, along the rectilinear stretch, the extension direction of the welding area of each unit has constant orientation with respect to the first direction.

[0163] Preferably, the mounting member supports a single welding unit.

[0164] Alternatively, for example in the case of multi-line product packaging machine or in the case of simultaneous welding, the mounting member supports two or more welding units.

[0165] Preferably, each welding unit is a welding and cutting unit. In other words, each welding unit is further configured to cut the web at the weld made. Preferably, the welding unit is configured to cut the web along a cutting line parallel to the main extension direction of the welding area.

[0166] The Applicant found that this feature allows for rapid finalization of the packaging of individual products by virtue of the combination of welding and cutting operated by the same welding unit.

[0167] Preferably, the welding unit comprises a cutting device.

[0168] Preferably, the welding unit comprises a blade sliding into a recess of the respective tool anvil and having a cutting edge operatively engaged in a corresponding recess of the welding tool.

[0169] Preferably, the recess is interposed between two adjacent welding areas of the same welding unit.

[0170] Preferably, the respective tool anvil comprises a base member on which the cutting blade is mounted and a movable body mounted on the base member and operatively engageable resting with the welding tool to perform the transverse welding.

[0171] Preferably, the movable body has the aforementioned recess in which the blade is housed and is movable with respect to the base member to allow a release of the blade from the recess following a predetermined approach of the movable body to the base member.

[0172] Preferably, the predetermined approach of the moving body to the base member is achieved, in particular, by means of an extra travel of the respective tool anvil operated by the movement mechanism after the gripping between the welding tool and the respective tool anvil.

[0173] The Applicant has found that this feature allows obtaining a very compact layout, in which the web is cut by the same welding unit simply with a further movement, in addition to the that required for welding, along the second direction.

[0174] Preferably, the welding tool is an ultrasonic tool.

[0175] Preferably, the continuous web lies in a flat positioning plane at least in the welding zone. Preferably, the axis about which the closed conveying path extends is transverse, preferably perpendicular, to the flat positioning plane of the web in the welding zone, so that the closed trajectories followed by the welding tool and the respective tool anvil are arranged about the axis.

[0176] Preferably, the movement of the mounting member along the closed conveying path about the axis is made by moving the mounting member according to a rotational movement about the axis.

[0177] Preferably, varying the position of the mounting member comprises varying:

[0178] - the distance of the mounting member from the axis,

[0179] - the angle of the mounting member about a respective axis of oscillation, preferably parallel to the second direction and / or to the axis, and

[0180] - the position of the mounting member along a direction tangential to the closed conveying path.

[0181] Such a variation of the position of the mounting member thus results in a preferably uniform, rectilinear translational movement of the mounting member along the first direction at the welding zone.

[0182] Preferably, the angle of the mounting member is varied by rotating each mounting member about the respective axis of oscillation.

[0183] Preferably, varying the position of the mounting member according to three degrees of freedom is operated by means of three independent actuators.

[0184] Preferably, such actuators are or comprise rotary servomotors, more preferably brushless motors.

[0185] Preferably, varying the distance of the mounting member from the axis and varying the position of the mounting member along a direction tangential to the closed conveying path are operated by means of two of the three actuators and made so as to determine the position of the axis of oscillation of the respective mounting member.

[0186] Preferably, varying the angle of the mounting member about the respective axis of oscillation is operated by means of the third actuator. Preferably, varying the angle of the mounting member about the respective axis of oscillation is made by rotating the mounting member about the axis of oscillation, in particular according to a periodic, reciprocal oscillatory movement during the movement of the mounting member about the axis and / or along the closed conveying path.

[0187] Preferably, moving the at least one welding unit comprises moving a plurality of welding units along the closed conveying path.

[0188] Preferably, the welding units are mounted on respective mounting members, where varying the position of each mounting member according to three degrees of freedom comprises varying the position of each mounting member according to three respective degrees of freedom, preferably independently of the other mounting members.

[0189] Preferably, each mounting member supports at least one respective welding unit. Preferably, during the movement of each mounting member, the at least one respective welding unit is moved accordingly along the closed conveying path so that the welding tool and the respective tool anvil of the at least one welding unit follow respective, mutually synchronized trajectories along the closed conveying path.

[0190] Preferably, such a simultaneous movement of the welding tool and the respective tool anvil of the at least one welding unit along respective, mutually synchronized trajectories is operated so that the welding tool and the respective tool anvil are moved or movable by reciprocal motion only along the second direction.

[0191] Preferably, the movement of at least one welding unit along the closed conveying path passing through the welding zone is performed by moving a plurality of welding units in sequence along the closed conveying path.

[0192] Preferably, the second direction is rectilinear, preferably transverse, preferably perpendicular to the first direction at least in the welding zone.

[0193] Preferably, the reciprocal motion between the welding tool and the respective tool anvil of at least one welding unit by performing at least one transverse weld on the web comprises cutting the web in an intermediate zone of the welding area by the same welding unit.

[0194] Preferably, the web cutting is performed and the welding tool and the respective tool anvil are in a web gripping configuration.

[0195] In an embodiment, the web is cut during the welding of the web.

[0196] Alternatively, the web cutting is performed after welding the web preferably by keeping the welding tool and the respective tool anvil in the same reciprocal gripping configuration used for welding.

[0197] Preferably, performing at least one transverse weld on the web is implemented by making an ultrasonic weld.

[0198] Brief description of the drawings

[0199] Further features and advantages of the present invention will be more apparent from the following description detailed preferred embodiments made with reference to the accompanying drawings.

[0200] In the drawings:

[0201] - figure 1 is a plan view of a welding device according to the present invention;

[0202] - figures 1A and 1 B are two perspective views of the device in figure 1 according to different angles;

[0203] - figure 2 is a perspective view of the welding device according to the present invention, with some parts removed;

[0204] - figure 2A is a plan view of the welding device according to the present invention;

[0205] - figure 3 is a plan view of the welding device according to the present invention, with some parts removed;

[0206] - figure 4 is a perspective view of a portion of the welding device according to the present invention, isolated from the other parts;

[0207] - figure 5 shows a perspective view of the welding device according to the present invention, with only one welding module shown, the other welding modules being removed; - figure 6 shows an enlarged detail of the welding device according to the present invention;

[0208] - figure 6A shows the detail in figure 6 with some parts shown in section;

[0209] - figure 7 shows a further enlarged detail of the portion in figure 4;

[0210] - figure 8 is a perspective view of a preferred embodiment of a component of the welding device according to the present invention;

[0211] - figures 9A-9C are diagrammatic views of respective operating steps of the component in figure 8;

[0212] - figures 10A and 10B are enlargements of figure 9B and 9C, respectively.

[0213] With reference to the accompanying figures, reference numeral 1 indicates as a whole a device for product packaging machines, in particular a device for making transverse welds on a continuous web "N", according to the invention.

[0214] Detailed description of preferred embodiments of the invention

[0215] The device 1 is applied in particular to a machine for packaging general products of different nature, e.g., belonging to the food, pharmaceutical or cosmetic industry.

[0216] Such a product packaging machine can be of the single-line type or the multi-line type according to the generality of the invention.

[0217] Hereafter in the present description, reference will be made to a machine operating on a single line for the sake of simplicity of presentation. However, the following disclosure described in relation to a single-line machine applies similarly to a multi-line machine.

[0218] In general, the machine comprises a feeder (not shown) of known type for feeding a sequence of items to be packaged and, preferably, a forming device (not shown) of known type for forming a continuous tubular web "N" wrapping the products. Downstream thereof, the machine further comprises the welding device 1 according to the invention, configured to weld and preferably cut the web "N” so as to obtain a plurality of packages "C", each containing one or more items wrapped in a preferably hermetic package. In particular, the device 1 is configured to automatically perform the aforesaid transverse welds and, preferably, the cut in equally spaced portions of the web "N” itself.

[0219] The device 1 comprises guide means (not illustrated) configured to feed at least the web "N" to be welded along a first direction "D1" through a welding zone "Z", where such a web "N" preferably has a tubular shape and wraps about one or more products of the sequence of products.

[0220] In the preferred embodiment, the guide means are configured to feed a single web “N” to be welded along a first direction “D1” through a welding zone “Z”.

[0221] In the case of a multi-line machine, the guide means are configured to feed at least one web “N” to be welded along a first direction “D1 ” through a welding zone “Z”.

[0222] According to an aspect of the invention, the guide means are configured to arrange the at least one web "N” with flat positioning in the welding zone "Z". The web “N” can further be wrapped about at least one product, and in the transverse welding zone, it is superimposed in a conventionally "tielike" shape. Preferably, the web “N” lies in a flat positioning plane at least in the welding zone “Z”.

[0223] Such guide means, according to known solutions, can comprise roller conveyors, tracking plate conveyors or the like.

[0224] The device 1 further comprises at least one conveyor 100 defining a closed conveying path "P" passing through the welding zone "Z" and at least one welding unit 200, configured to transversely weld the web "N" and mounted on the at least one conveyor 100 to follow the closed conveying path "P”. In particular, the at least one welding unit 200 is configured to define a respective welding area. In other words, the at least one welding unit 200 is moved by the conveyor 100 along the closed conveying path "P" cyclically passing through the welding zone "Z".

[0225] According to an aspect of the invention, in the embodiment illustrated and described below, the welding units 200 are of the ultrasonic type, however the following description will also apply to heat welding units 200 or to units of a different nature (e.g., induction or cold welding units) except when explicitly incompatible with the nature of the products to be packaged or with particular process specifications.

[0226] In the embodiment shown in the accompanying figures, the device 1 comprises a single conveyor 100 and a plurality of welding units 200, arranged in sequence along the closed conveying path "P".

[0227] The number of welding units 200 can be chosen as a function of specific requirements, such as the maximum allowable size of device 1 , the number of welds to be made in the unit of time, the speed of the web "N", the welding time, the dimensions of the product to be packed, and others, for example.

[0228] The movement of the welding units 200 along the closed conveying path "P" passing through the welding zone "Z" is performed by moving the plurality of welding units 200 in sequence along the closed conveying path "P". According to an aspect of the invention, the respective closed trajectories of welding units 200 in sequence along the closed conveying path "P" are substantially identical to each other.

[0229] At the functional level, each welding unit 200 is configured to define at least one respective welding area having extension direction mainly transverse to the first direction "D1". Preferably, each welding unit 200 is configured to define at least one respective welding area having extension direction mainly perpendicular to the first direction "D1". The welding area can have any shape. Preferably, the welding area has an overall rectangular shape and / or extension. According to constructional variants, not shown, the welding area can have any shape, also irregular or non- rectilinear, according to specific types of welds to be made.

[0230] The peculiar structure and further technical features of the welding units 200 will be further clarified hereafter in the present description.

[0231] Preferably, the closed path "P" lies in a flat positioning plane. According to an aspect of the present invention, the closed conveying path "P" extends about an axis "X".

[0232] Such an axis "X" is preferably perpendicular to the positioning plane of the closed conveying path "P". Preferably, in other words, the movement of the welding units 200 along the closed conveying path "P" is performed by moving them according to a general closed path which extends about the aforesaid axis "X". Such a closed path can be circular or non-circular.

[0233] In the illustrated embodiment, the conveyor 100 can comprise a rotating conveyor 100 rotatable about the aforesaid axis "X". The axis "X" is transverse to the first direction "D1". In particular, the axis is perpendicular to the first direction "D1". Moreover, the axis is perpendicular to the positioning plane of the web "N" in the welding zone "Z". Preferably, in other words, the continuous web "N" lies in a flat positioning plane at least in the welding zone "Z", and the movement of the welding units 200 along the closed conveying path "P" is performed by moving the welding units 200 about an axis "X" that is transverse, preferably perpendicular, to the positioning plane of the web "N" in the welding zone "Z".

[0234] Structurally, the conveyor 100 comprises a central shaft or support (not shown), which is rotatable about the aforesaid axis "X", and at least one mounting member 400, configured to support at least one respective welding unit 200 and connected to the central shaft by a respective conveying mechanism 300.

[0235] According to the illustrated embodiment, the conveyor 100 comprises a plurality of mounting members 400, angularly distributed about the axis "X" of the conveyor 100 and preferably equidistant. Each mounting member 400 supports a respective welding unit 200 of the aforesaid plurality of welding units 200 (however, each mounting member 400 could support more than one respective welding unit 200).

[0236] Thus, the plurality of mounting members 400 are arranged in sequence along the closed conveying path "P". Preferably, each conveying mechanism 300 is independent so that it moves the respective mounting member 400 independently of the other mounting members 400.

[0237] Each conveying mechanism 300 is active on the respective mounting member 400 and configured to vary the position of the respective mounting member 400 according to three degrees of freedom as the mounting member 400 moves about the axis “X” so that the conveying path “P” has at least one rectilinear stretch parallel to the first direction “D1 ” at least in the welding zone “Z”.

[0238] In greater detail, each conveying mechanism 300 is active on the respective mounting member 400 to vary the angle of the mounting member 400 by rotating the mounting member 400 about a respective axis of oscillation "Y" parallel to the axis "X" of the conveyor 100, and in addition to determine the spatial position of the axis "Y” itself, in particular in a plane perpendicular to the axis "Y".

[0239] Preferably, in other words, the movement of the at least one welding unit 200 about the axis "X” is made by both the basic rotational movement about the axis "X”, linked to the rotation of the conveyor 100, and an additional movement according to a combined movement towards and away from the axis "X" (radial component, first degree of freedom), of tangential displacement with respect to the rotation trajectory about the axis "X" and along the first direction "D1" (tangential component, second degree of freedom), and of rotation about the respective axis of oscillation "Y" (orientation component, third degree of freedom) during the movement of the mounting member 400 and thus of the welding unit 200 along the closed conveying path "P".

[0240] Preferably, the axis of oscillation "Y" is parallel to the axis "X" of the conveyor 100.

[0241] As for the conveying mechanism 300, it is preferably of the articulated type. More preferably, each conveying mechanism 300 comprises an articulated linkage 310 and an auxiliary linkage 320.

[0242] The articulated linkage 310 has two degrees of freedom so that it can govern the positioning of the mounting member 400, and in particular of the axis of oscillation "Y", in a plane perpendicular to the latter.

[0243] In greater detail, the articulated linkage 310 is connected to the mounting member 400 rotatably about the axis of oscillation "Y", e.g., by means of a hinge or a bushing with bearings, so as to set the position of the axis of oscillation "Y" but allowing the free rotation of the mounting member 400 about the axis of oscillation "Y". Therefore, the axis of oscillation "Y" can always have the same spatial orientation, in particular a condition of parallelism with the axis "X" of the conveyor 100.

[0244] In the illustrated embodiment (figure 4), the articulated linkage 310 comprises a first rotary lever 311 and a second rotary lever 312, both defining respective arms of the articulated linkage 310 and preferably operable in a mutually independent manner.

[0245] The first rotary lever 311 is rotatable about a first actuation axis "H1 " while the second rotary lever 312 is rotatable about a second actuation axis "H2".

[0246] Preferably, the first and second rotary levers 311 , 312 are mounted coaxially with each other. In other words, the first and second actuation axes "H1", "H2" are coincident with each other. However, according to embodiments not shown, such actuation axes "H1", "H2" can be parallel and mutually spaced apart.

[0247] Preferably, moreover, the conveying mechanism 300 further comprises, for each mounting member 400, at least one auxiliary linkage 320 connected to the mounting member 400 in an eccentric position with respect to the axis of oscillation "Y" so as to cause a rotation of the mounting member 400 about the axis of oscillation "Y".

[0248] In an embodiment (not shown), the auxiliary linkage is connected to the mounting member in a position coaxial to the axis of oscillation, e.g., by means of a bushing or other transmission member rotatable about the axis of oscillation or by means of a rotary motor rotatable about the axis of oscillation.

[0249] Preferably, the auxiliary linkage 320 comprises a third rotary lever 321 , rotatable about the third “H3” of the three actuation axes.

[0250] Preferably, the third rotary lever 321 is connected to the mounting member 400 by means of a link rod 322, in particular in an eccentric position with respect to the axis of oscillation “Y” and by means of a hinge connection.

[0251] Preferably, the third rotary lever 321 is mounted eccentrically with respect to the first and second rotary levers 311 , 312, i.e., with the third actuation axis "H3" spaced apart from (even if parallel to) the first and second actuation axes "H1", "H2".

[0252] Preferably, according to the illustrated embodiment, the conveying mechanism 300 comprises a first and a second articulated linkage 310, 310', where the first articulated linkage 310 is connected to a first (upper) end of the mounting member 400 while the second articulated linkage 310' is connected to a second (lower) end of the mounting member 400, opposite to the first end. The first and second ends of the mounting member 400 are aligned along a (vertical) direction parallel to the second direction "D2" and / or to the axis "X" of the conveyor 100.

[0253] Preferably, moreover, the conveying mechanism 300 further comprises a first and a second auxiliary linkage 311 , 31 T, where the first auxiliary linkage 311 is connected to the first (upper) end of the mounting member 400 while the second auxiliary linkage 31 T is connected to the second (lower) end of the mounting member 400.

[0254] The first and second articulated linkages 310, 310' are movable synchronously so as to perform the same movement of the mounting member 400.

[0255] Preferably, the first and second articulated linkages 310, 310' are connected to each other so as to follow mutually identical motion laws. As better shown in figures 4 and 6, the first rotary lever 311 of the first articulated linkage 310 and the first rotary lever 311 ’ of the second articulated linkage 310’ are coaxial with each other and rigidly connected at least in a rotation movement about the first actuation axis “H1”, in particular by means of a first connection shaft 313.

[0256] Preferably, the second rotary lever 312 of the first articulated linkage 310 and the second rotary lever 312’ of the second articulated linkage 310’ are coaxial with each other and rigidly connected at least in a rotation movement about the second actuation axis “H2”, in particular by means of a second connection shaft 314.

[0257] Preferably, the first and second shafts 313, 314 are mutually coaxial and rotationally independent. In particular, the first shaft 313 is hollow and the second shaft 314 is inserted therein.

[0258] As shown in figures 6 and 6A, the first shaft 313 has a side window 313a from which the second rotary lever 312 associated with the second shaft 314 comes out. Such a side window 313a is arranged at the second rotary lever 312 of the first (upper) articulated linkage 310. Such a side window can be omitted at the second (lower) articulated linkage 310' because the respective second rotary lever 312' can be axially outside the first shaft 313 (figure 7).

[0259] Such a side window 313a has an angular width, about the first and / or second actuation axis "H1", "H2", sufficient to allow the mutual operating rotation (oscillation) between the first and second rotary levers 311 , 312, and thus between the first and second shafts 313, 314. Preferably, the angular width is between 90° and 270°.

[0260] The first and second auxiliary linkages 320, 320’ are also movable synchronously so as to perform the same oscillation movement of the mounting member 400.

[0261] Preferably, the first and second auxiliary linkages 320, 320' are connected to each other so as to follow mutually identical motion laws. Preferably, the third rotary lever 321 of the first auxiliary linkage 320 and the third rotary lever 321 ’ of the second auxiliary linkage 320’ are coaxial with each other and rigidly connected at least in a rotation movement about the third actuation axis “H3”, in particular by means of a third connection shaft 315.

[0262] Preferably, the third connection shaft 315 is parallel to the first and second shafts 313, 314 and spaced apart therefrom.

[0263] Preferably, the conveying mechanism 300 further comprises three actuators 330, 340, 350 for each mounting member 400, each of which is configured to adjust a respective one of the three degrees of freedom.

[0264] Preferably, the three actuators 330, 340, 350 are mutually independent and / or independently controllable.

[0265] Preferably, the three actuators 330, 340, 350 are connected to the first rotary levers 311 , 311 ’, the second rotary levers 312, 312’, and the third rotary levers 321 , 321 ’, respectively.

[0266] Preferably, each actuator 330, 340, 350 is or comprises a rotary servomotor, preferably a brushless motor.

[0267] Preferably, each rotary servomotor is arranged with its rotation axis parallel to the "X" axis of the conveyor 100 and / or to the axis of oscillation "Y"

[0268] Preferably, the first actuator 330 is active on the first rotary levers 311 , 311 ’ and is arranged with its axis "Z1 ” coincident with the first actuation axis "H1 ", thus coaxially to the first rotary levers 311 , 311 ’ (figures 2A and 3).

[0269] Preferably, the second actuator 340 is active on the second rotary levers 312, 312’ and is arranged with its axis "Z2" parallel and offset with respect to the second actuation axis "H2". This is obtained by using a mechanical transmission 341 (figure 3), in particular a pair of toothed wheels or other equivalent transmission (e.g., a belt or chain transmission). Preferably, the third actuator 350 is active on the third rotary levers 321 , 321 ’ and is arranged with its axis "Z2" coincident with the third actuation axis "H3".

[0270] The conveyor 100 further comprises a first and a second wall 110, 120, parallel and opposed to each other, and transverse, preferably perpendicular, to the axis "X” of the conveyor 100. In particular, the two walls 110, 120 are spaced apart from each other so that the conveying mechanisms 300 are arranged in a region (annular in shape) enclosed between the two walls 110, 120. In particular, the first wall 110 is the upper wall while the second wall 120 is the lower wall.

[0271] In an embodiment, at least one of the two walls 110, 120, preferably both, has a preferably circular, plate-like shape.

[0272] Alternatively, the walls 110, 120 can have a different structure, e.g., meshlike or dial-like.

[0273] Each conveying mechanism 300 is mounted on the two walls 110, 120, in particular (exclusively) supported by the two walls 110, 120.

[0274] In particular, the walls 110, 120 have holes for the insertion of the first, second, and third shafts 313, 314, 315 for each mounting member 400.

[0275] Preferably, two of the actuators 330, 340, 350, and more preferably the actuators 330, 340 associated with the first and second actuation axes "H1 ", "H2" or shaft 313, 314, are mounted on the first (upper) wall 110 and the third actuator 350 is mounted on the second (lower) wall 120.

[0276] A preferred exemplary, and thus non-limiting, embodiment of the welding unit 200 and the respective mounting member 400 will now be described with reference to figures 8, 9A-9C and 10A-10B.

[0277] Structurally, each welding unit 200 comprises a welding tool 201 and a respective tool anvil 202 movable along respective closed trajectories “T1”, “T2” passing through the welding zone “Z” and movable by reciprocal motion towards and away from each other along a second direction “D2”. Preferably, the welding tool 201 comprises an ultrasonic welder (sonotrode). The trajectories "T1 ," "T2" are substantially circular and extend about respective axes "X1 ," "X2". Preferably, such axes "X1" and "X2" are substantially coincident. More preferably, such axes "X1" and "X2” coincide with the aforesaid axis "X" of the conveyor 100.

[0278] More generally, taking into account different embodiments from those shown, the axes "X1" and "X2” of the closed trajectories "T1 ," "T2" are substantially parallel to each other although not necessarily coincident. Preferably, each of such axes "X1" and "X2" pass in both closed trajectories "T1 ", "T2".

[0279] Moreover, preferably, the trajectories "T1 ," "T2" lie in a substantially flat positioning plane except for a stretch in which they deviate from the flat positioning plane, in particular in the welding zone. Indeed, in such a zone, each welding tool 201 and the respective tool anvil 202 are provided with movement along the second direction "D2" and thus move away from the positioning plane of the respective trajectory "T1 ," "T2".

[0280] At the functional level, the welding tool 201 and the tool anvil 202 are movable by reciprocal motion along the second direction so as to define at least one disengaged configuration, in which the welding tool 201 and the respective tool anvil 202 are spaced away from each other, and a gripping configuration, suitable for making the transverse weld of the web “N”, in which the welding tool 201 and the respective tool anvil 202 abut against each other at the welding area.

[0281] According to an aspect of the present invention, the at least one conveyor 100 is configured so that the welding tool 201 and the respective tool anvil 202 have a reciprocal motion only towards and away from each other along the second direction “D2”.

[0282] In particular, the at least one welding unit 200 is moved along the closed conveying path “P” so that the welding tool 201 and the respective tool anvil 202 of each welding unit 200 have a reciprocal motion only towards and away from each other along the second direction “D2”. In other words, during the movement of each welding unit 200 along the closed conveying path “P”, the welding tool 201 and / or the respective tool anvil 202 are also moved along the second direction “D2” so as to grip and compress at least one portion of the web “N” making at least one transverse weld, respectively.

[0283] According to an aspect of the present invention, the second direction "D2" is rectilinear. Moreover, the second direction "D2" is transverse, in particular perpendicular, to the first direction "D1" at least in the welding zone "Z". Again, the second direction "D2" is parallel to the rotation axis "X" of the rotating conveyor 100 and to the axis of oscillation "Y" of the respective mounting member 400.

[0284] In use, the second direction “D2” has a substantially constant orientation during the movement of the welding unit 200 along the closed conveying path “P”. In other words, the second direction "D2" has constant orientation with respect to the first direction "D1" and with respect to the axis of the conveyor 100.

[0285] According to an aspect of the present invention, the conveyor 100 is configured so that the closed trajectories “T1”, “T2” followed by each welding tool 201 and by the respective tool anvils 202 have at least one rectilinear stretch which passes through the welding zone “Z” and which is, in particular, parallel to the first direction “D1 ” at least in the welding zone “Z”. Such rectilinear stretches of the closed paths "T1", "T2" are preferably parallel to each other and parallel to the rectilinear stretch "P1" of the closed path "P".

[0286] In other words, the movement of the at least one welding unit 200 along the closed conveying path “P” is performed by moving each welding unit along a closed conveying path 200 having at least one rectilinear stretch which is parallel to the first direction “D1 ” at least in the welding zone “Z”. According to an aspect of the present invention, the respective closed trajectories of the welding tool 201 and the respective tool anvil 202 overlap each other, preferably being substantially identical or symmetrical, at least in the respective rectilinear stretch "P1" passing through the welding zone "Z”.

[0287] For such a purpose, in the embodiment described here, the welding tool 201 and the respective tool anvil 202 are mounted on the same conveyor 100, and in particular on the same mounting member 400. Alternatively, two conveyors 100 arranged coaxially along the (coincident) rotation axis "X" thereof can be provided, in which a first conveyor 100 supports the welding tool 201 and the second conveyor 100 supports the tool anvil 202. According to an aspect of the present invention, each mounting member 400 supports at least one welding unit 200 so that the welding tool 201 and the respective tool anvil 202 of each welding unit 200 move along respective closed trajectories mutually synchronized along the closed conveying path “P”. Preferably, in other words, the movement of the at least one welding unit 200 along the closed conveying path “P” is performed by simultaneously moving the welding tool 201 and the respective tool anvil 202 of the at least one welding unit 200 along respective trajectories “T1”, “T2” mutually synchronized along the closed conveying path “P”.

[0288] In the preferred embodiment, the mounting member 400 supports a single welding unit 200.

[0289] According to an aspect of the present invention, each mounting member 400 comprises a respective movement mechanism 500 configured to move the welding tool 201 and the respective tool anvil 202 of the respective welding unit 200 by reciprocal motion along the second direction “D2”.

[0290] The assembly formed by a mounting member 400 and one or more respective welding units 200 mounted thereon (and optionally with the respective movement mechanism 300) defines a tracking "welding module". Such a module is referred to by reference numeral 10 as a whole. Preferably, the welding device 1 comprises a plurality of welding modules 10 arranged in sequence along the closed conveying path "P". Preferably, the welding modules 10 are moved along the same closed conveying path npn

[0291] In other words, each welding module 10 comprises the aforementioned mounting member 400, adapted to be moved along the first tracking direction "D1" of the web "N" and having a rigid configuration, even more preferably monolithic, and at least one welding unit 200 mounted on the mounting member 400 and configured to define the aforesaid welding area.

[0292] The module 10 further comprises a respective movement mechanism 500 of the at least one welding unit 200, mounted on the mounting member 400 and configured to move the welding tool 201 and / or the respective tool anvil 202 at least along the second direction “D2”.

[0293] At the functional level, the welding method performed by employing the aforesaid welding module 10 includes feeding the web "N" continuously along the first direction "D1" through a welding zone "Z", moving the mounting member 400 along the first direction "D1", in particular over a rectilinear stretch of a predetermined length so that the mounting member 400 moves to track the web "N" at least in the welding zone "Z", and moving the welding tool 201 and the respective tool anvil 202 by reciprocal motion along the second direction "D2" during the movement of the mounting member 400 along the first direction "D1" through the welding zone "Z" so as to grip and compress at least one portion of the web "N" thus performing the at least one transverse welding.

[0294] A preferred and thus non-limiting exemplary embodiment of the movement mechanism 500 of the tool 201 and tool anvil 202 with reference to the mounting member 400 with which it is associated will now be described hereafter in the present description, with reference to figures 8, 9A-9C and 10A-10B. According to an aspect of the present invention, the movement mechanism 500 is configured to move both the welding tool 201 and the respective tool anvil 202 according to the aforesaid reciprocal motion towards and away from each other along the second direction "D2". In other words, the reciprocal motion of the welding tool 201 and the respective tool anvil 202 is performed by moving both the welding tool 201 and the respective tool anvil 202 in the welding zone “Z”.

[0295] According to an aspect of the present invention, the movement mechanism 500 is configured to move the welding tool 201 and the respective tool anvil 202 along the second direction “D2” independently of each other.

[0296] According to an aspect of the present invention, the movement mechanism 500 is housed at least partially within the respective mounting member 400.

[0297] In particular, each mounting member 400 has a preferably monolithic, more preferably plate-shaped, rigid structure. The mounting member 400 has a preferably flat partition wall 405, adapted to separate an operation zone, housing the at least one movement mechanism 500, from a processing zone, opposite to the operation zone and housing the at least one welding unit 200. Preferably, the welding area has extension direction mainly transverse to the partition wall 405. Even more preferably, the welding area has an extension direction mainly perpendicular to the partition wall 405.

[0298] The mounting member 400 comprises a frame 410 having a closed box shape with an internal space which delimits the operation zone and configured house the movement mechanism 500 to at least partly; preferably, the box-shaped frame 410 frontally defines the aforesaid partition wall 405.

[0299] According to the present invention, the mounting member 400 comprises one or more dynamic hermetic gaskets arranged to hermetically seal the internal space and interposed between the respective welding unit 200 and the respective movement mechanism 500.

[0300] The at least one movement mechanism 500 crosses the partition wall 405 at at least one opening so as to be connected to the at least one welding unit 200; the at least one opening is associated with dynamic hermetic gaskets so as to hermetically isolate the internal space from the exterior. Alternatively, the at least one opening is associated with dynamic non- hermetic gaskets.

[0301] Moreover, preferably, the at least one opening has a circular profile.

[0302] According to an aspect of the present invention, the dynamic hermetic gaskets comprise a first disc 510 rotatably inserted into the opening and rotatable with respect to the partition wall 405; the first disc 510 comprises, in turn, at least one circular-profile hole positioned eccentrically with respect to the center of the first disc 510.

[0303] According to an aspect of the present invention, the dynamic hermetic gaskets further comprise a second disc 520, inserted into the hole of the first disc 510 and rotatable with respect to the first disc 510; the second disc 520, in turn, comprises a circular hole positioned eccentrically with respect to the center of the second disc 520 itself. Preferably, the hole of the second disc 520 is crossed by a shaft-like portion 530 of the movement mechanism 500.

[0304] According to an aspect of the present invention, the partition wall 405, the first disc 510, the second disc 520 and the shaft-like portion 530 are mutually connected by hermetic sliding couplings. The at least one movement mechanism 500 crosses the partition wall 405 at at least two openings so as to be connected to the welding tool 201 and to the respective tool anvil 202 of the welding unit 200.

[0305] According to an aspect of the present invention, for at least one of the pair of welding tool 201 and respective tool anvil 202, preferably for both, the movement mechanism 500 comprises a guide 560, a carriage 540, and an actuator 550, shown in figure 8 and figures 9A-9C. The guide 560 is linear and parallel to the second direction "D2". The carriage 540 is slidably mounted on the guide 560 and connected to the welding tool 201 or to the respective tool anvil 202. The actuator 550 is connected instead to the carriage 540 to move the carriage 540 with a controlled to-and-fro movement along the guide 560. Preferably, the actuator 550 comprises an electric motor and a mechanical transmission, preferably a crank mechanism. Functionally, the movement mechanism 500 is configured to move the shaft-like portion 530 of the movement mechanism 500 along a rectilinear trajectory and impart movements to the first disc 510 and to the second disc 520 according to independently controllable movements.

[0306] According to an aspect of the present invention, each welding unit 200 is further configured to cut the web “N” at the weld made. Preferably, the welding unit 200 is configured to perform the cutting of the web "N" along a cutting line parallel to the main extension direction of the welding area.

[0307] At the functional level, in the reciprocal motion of the welding tool 201 and the respective tool anvil 202 of at least one welding unit 200 (adapted to make at least one transverse weld on the web "N"), the web "N” is cut in an internal, preferably intermediate zone of the welding area by the same welding unit 200, in particular while the welding tool 201 and the respective tool anvil 202 are in a gripping configuration of the web "N". Preferably, the web "N” is cut during the welding of the web "N”. Alternatively, the web "N” is cut after the welding of the web "N".

[0308] For such a purpose, the welding unit 200 comprises a cutting device 210. In particular, the welding unit 200 comprises a blade 211 slidingly inserted into a recess 212 of the respective tool anvil 202 and having a cutting edge operatively engaged in a corresponding recess 213 of the welding tool 201.

[0309] In the preferred embodiment shown in the accompanying figures, the respective tool anvil 202 comprises a base member 220 on which the cutting blade 211 is mounted and a movable body 221 mounted on the base member 220 and operatively engaged in support with the welding tool 201 to perform the transverse welding. The movable body 221 has the aforesaid recess 212 in which the blade 211 is housed and is movable with respect to the base member 220 to allow for a release of the blade 211 from the recess 212 following a predetermined approach of the movable body 221 to the base member 220.

[0310] According to an aspect of the present invention, the predetermined approach of the moving body 221 to the base member 221 is particularly achieved by an extra travel of the respective tool anvil 202 operated by the movement mechanism 500 after the gripping between the welding tool 201 and the respective tool anvil 202.

[0311] Figures 8 and 9A show the disengaged configuration of the welding tool 201 and the respective tool anvil 202.

[0312] Figures 9B and 10A show the welding configuration of the welding tool 201 and the respective tool anvil 202.

[0313] Figures 9C and 10B show the extra travel or cutting configuration of the welding tool 201 and the respective tool anvil 202.

[0314] The present invention achieves its intended purposes by eliminating the drawbacks highlighted in the prior art.

[0315] Indeed, the device according to the invention is permanently synchronized with reference to the trajectories of the welding tools and the tool anvils, and does not require complex adjustment or correction systems. Moreover, the possibility to perform a tracking welding allows increasing the web feeding speed, thus increasing machine productivity, while ensuring welds of a predetermined quality.

Claims

CLAIMS1 . A welding device (1 ) for product packaging machines, comprising: guide means configured to feed at least one web (N) to be welded along a first direction (D1 ) through a welding zone (Z);- at least one conveyor (100) defining a closed conveying path (P) which extends around an axis (X) and comprising at least one mounting member (400) which is movable around said axis (X) along said closed conveying path (P);- at least one welding unit (200) configured for transversely welding said web (N) and comprising a welding tool (201 ) and a respective tool anvil (202), said at least one welding unit (200) being mounted on said at least one mounting member (400) to follow said closed conveying path (P) so that said welding tool (201 ) and said respective tool anvil (202) of each welding unit (200) move along respective closed trajectories (T1 , T2) which are synchronized with each other along said closed conveying path (P) and are also movable with reciprocal motion towards and away from each other along a second direction (D2), wherein said conveyor (100) comprises a conveying mechanism (300) acting on said at least one mounting member (400) and configured to vary the position of said at least one mounting member (400) according to three degrees of freedom as the mounting member (400) moves around said axis (X) so that said conveying path (P) has at least one rectilinear stretch parallel to the first direction (D1 ) at least in the welding zone (Z).

2. The device (1 ) according to claim 1 , wherein said conveying mechanism (300) is configured to vary the distance of each mounting member (400) from said axis (X), the angle of each mounting member (400) around a respective axis of oscillation (Y), preferably parallel to said second direction (D2) and / or to said axis (X), and the position of the mounting member (X) along a direction tangential to the closed conveying path (P) so that each mounting member (400) moves with translational motionwhich is rectilinear and preferably uniform along the first direction (D1 ) at the welding zone (Z).

3. The device (1 ) according to claim 1 or 2, wherein varying the position of said at least one mounting member (400) according to three degrees of freedom is accomplished through respective actuating movements around three actuation axes (H1 , H2, H3).

4. The device (1 ) according to claim 3, wherein said three actuation axes (H1 , H2, H3) are parallel to each other.

5. The device (1 ) according to claim 3 or 4, wherein said three actuation axes (H1 , H2, H3) are coincident with each other.

6. The device (1 ) according to any one of claims 2 to 5, wherein said conveying mechanism (300) comprises at least one articulated linkage (310, 310') having two degrees of freedom and connected to the mounting member (400) rotatably about said axis of oscillation (Y) so as to set the position of said axis of oscillation (Y), and wherein said conveying mechanism (300) also comprises at least one auxiliary linkage (320, 320') connected to the mounting member (400) at an eccentric position relative to said axis of oscillation (Y) to cause a rotation of the mounting member (400) about the axis of oscillation (Y).

7. The device according to claim 6, wherein said articulated linkage (310, 310') comprises a first rotary lever (311 , 31 T) and a second rotary lever (312, 312'), both defining respective arms of the articulated linkage (310, 310'), and wherein said auxiliary linkage (320, 320') comprises a third rotary lever (321 , 32T), preferably connected to the mounting member (400) by a link rod (322, 322').

8. The device according to claim 7, wherein said first and second rotary levers (311 , 312; 31 T, 312') are mounted coaxially with each other, said third rotary lever (321 , 32T) being mounted preferably eccentrically relative to said first and second rotary levers (31 1 , 312; 311 ’, 312’).

9. The device (1 ) according to any one of claims 6 to 8, wherein said conveying mechanism (300) comprises a first and a second articulated linkage (310, 310') and a first and a second auxiliary linkage (320, 320'), and wherein the first articulated linkage (310) and the first auxiliary linkage (320) are connected to a first end of the mounting member (400), while the second articulated linkage (310') and the second auxiliary linkage (320') are connected to a second end of the mounting member (400), said first and second ends of the mounting member (400) being opposite each other.

10. The device (1 ) according to any one of the preceding claims, wherein said conveying mechanism (300) comprises three independent actuators (330, 340, 350) for each mounting member (400), each actuator (330, 340, 350) being configured to adjust a respective one of said degrees of freedom.

11. The device (1 ) according to claim 10, when dependent on claim 7, wherein said actuators (330, 340, 350) are connected respectively to the first rotary lever (311 , 31 T), to the second rotary lever (312, 312') and to the third rotary lever (321 , 321 ').

12. The device (1 ) according to claim 10 or 11 , wherein each actuator (330, 340, 350) comprises a rotary servomotor, preferably a brushless motor.

13. The device (1 ) according to any one of the preceding claims, whereinsaid conveyor (100) comprises a first and a second wall (110, 120), parallel and opposite each other and transverse, preferably perpendicular, to said axis (X), and wherein said conveying mechanism (300) is located in a region between said walls (110, 120).

14. The device (1 ) according to claims 10 and 13, wherein two of said actuators (330, 340) are mounted on the first wall (110) and the third actuator (350) is mounted on the second wall (120).

15. The device (1 ) according to any one of the preceding claims, wherein the conveyor (100) comprises a plurality of mounting members (400) distributed around said axis (X) and a plurality of conveying members (300), each associated with a respective mounting member (400) to adjust the position of said respective mounting member (400) according to three degrees of freedom as the mounting member (400) moves along the closed path (P).

16. The device (1 ) according to claim 15, wherein said conveying mechanisms (300) are operable independently of each other.

17. The device (1 ) according to any one of the preceding claims, wherein the closed conveying path (P) lies in a flat positioning plane and wherein said axis (X) is perpendicular to the positioning plane of the closed conveying path (P).

18. The device (1 ) according to any one of the preceding claims, wherein said at least one conveyor (100) comprises at least one conveyor (100) that rotates about said axis (X).

19. The device (1 ) according to any one of the preceding claims, wherein each mounting member (400) has a rigid structure, preferably monolithic,and more preferably, plate shaped.

20. The device (1 ) according to any one of the preceding claims, wherein each mounting member (400) comprises a respective movement mechanism (500) configured to move the welding tool (201 ) and the respective tool anvil (202) of the respective welding unit (200) reciprocally along the second direction (D2).

21. The device (1 ) according to claim 20, wherein each mounting member (400) has a box-shaped configuration defining an internal space which accommodates the movement mechanism (500), preferably entirely.

22. The device (1 ) according to claim 21 , wherein the mounting member (400) comprises one or more dynamic hermetic gaskets disposed to hermetically seal the internal space and interposed between the respective welding unit (200) and the respective movement mechanism (500).

23. The device (1 ) according to any one of the preceding claims, wherein the welding tool (201 ) is an ultrasonic welding tool.

24. A welding method, in particular implemented using a device (1 ) according to any one of the preceding claims, comprising:- feeding at least one web (N) along a first direction (D1 ) through a welding zone (Z);- moving at least one welding unit (200) along a closed conveying path (P) extending around an axis (X) and passing through the welding zone (Z), said at least one welding unit (200) being configured for transversely welding said web (N) and comprising a welding tool (201) and a respective tool anvil (202) that are movable by reciprocal motion towards and away from each other along a second direction (D2), moving said at least one welding unit (200) along said closed conveying path (P) beingaccomplished by moving the welding tool (201 ) and the respective tool anvil (202) along respective closed trajectories (T1 , T2) passing through the welding zone (Z); while moving the at least one welding unit (200) along the closed conveying path (P), also moving the welding tool (201 ) and / or the respective tool anvil (202) along the second direction (D2) so as to grip and compress at least one portion of the web (N) to make at least one transverse weld, wherein said welding unit (200) is mounted on a respective mounting member (400) and wherein moving the at least one welding unit (200) along the closed conveying path (P) comprises moving the mounting member (400) around said axis (X) and also comprises, in at least part of the closed conveying path (P), varying the position of said at least one mounting member (400) according to three degrees of freedom so that said conveying path (P) has at least one rectilinear stretch parallel to the first direction (D1 ) at least in the welding zone (Z).

25. The method according to claim 24, wherein said web (N) lies in flat positioning plane at least in said welding zone (Z) and wherein said axis (X) is transverse, preferably perpendicular, to said flat positioning plane of the web (N) in the welding zone (Z), so that the closed trajectories (T1 , T2) followed by the welding tool (201 ) and the respective tool anvil (202) are disposed around said axis (X).

26. The method according to claim 24 or 25, wherein moving the mounting member (400) around said axis (X) is accomplished by moving the mounting member (400) by rotational motion about the axis (X).

27. The method according to any one of claims 24 to 26, wherein varying the position of the mounting member (400) comprises varying the distance of each mounting member (400) from said axis (X), the angle of eachmounting member (400) around a respective axis of oscillation (Y), preferably parallel to said second direction (D2) and / or to said axis (X), and the position of the mounting member (X) along a direction tangential to the closed conveying path (P) so that each mounting member (400) moves with translational motion which is rectilinear and preferably uniform along the first direction (D1 ) at the welding zone (Z).

28. The method according to any one of claims 24 to 27, wherein varying the position of said at least one mounting member (400) according to three degrees of freedom is carried out by three independent actuators (330, 340, 350), in particular via three rotary, preferably brushless, servomotors.

29. The method according to claim 28, when dependent on claim 27, wherein varying the distance of the mounting member (400) from said axis (X) and varying the position of the mounting member (X) along a direction tangential to the closed conveying path (P) are carried out by two of said three actuators (330, 340) and performed in such a way as to determine the position of the axis of oscillation (Y), and wherein varying the angle of each mounting member (400) around the respective axis of oscillation (Y) is carried out by the third of said actuators (350) and performed by rotating the mounting member (400) about the axis of oscillation (Y).

30. The method according to any one of claims 24 to 29, wherein moving at least one welding unit (200) comprises moving a plurality of welding units (200) along said closed conveying path (P), said welding units (200) being mounted on respective mounting members (400), and wherein varying the position of said at least one mounting member (400) according to three degrees of freedom comprises varying the position of each mounting member (400) according to three degrees of freedom, preferably independently of the other mounting members (400).31 . The method according to any one of claims 24 to 30, wherein making at least one transverse weld on the web (N) is accomplished by ultrasonic welding.

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