IT201700019361A1 - WELDING CUTTER MACHINE - Google Patents

Description

Cutting-welding machine

Description

Technical field

The present invention relates to a machine for cutting and sealing a web-like material, for example a plastic film, for packaging groups of products. More specifically, the embodiments described here relate to a cutting-sealing machine for cutting and sealing a film of plastic material wrapped in a tubular form around groups of articles to be packaged.

State of the art

In many industrial sectors there is a need to group products or articles from a production line and wrap them in a wrapping sheet or packaging film. For example, in the production of tissue paper rolls, paper handkerchiefs or paper napkins, it is common to collect a certain number of items in packages, formed by a sealed plastic film, and possibly to insert a plurality of such packages in bags, in turn formed by a welded plastic film.

The packaging process must take place at high speed, compatible with the production speed of the upstream machines, for example rewinders that produce tissue paper rolls at high speed.

Usually it is envisaged to group in an orderly manner a plurality of articles, each of which can be constituted in turn by a multiplicity of products, for example rolls of tissue paper, and to sequentially introduce ordered groups of articles inside a tubular of plastic film which is formed continuously around a forming collar. The continuous flow of groups of items inside the plastic film tube must be divided into individual packs, by cutting and welding the plastic film tube at two opposite ends of the groups of ordered articles. These operations require complex machines, which perform continuous cutting and welding of the plastic film tubing. These machines can represent a slowdown point in the production line.

Examples of cutting-welding machines of the prior art are described in EP-A-1442984 and in US-A-5.433.063.

There is a constant need to create efficient and reliable cutting-welding machines, capable of overcoming or alleviating the drawbacks of current art machines.

Summary of the invention

According to one aspect, a cutting-sealing machine is provided for sealing and cutting a packaging film for packages of products wrapped in said film, comprising a path for advancing the products wrapped in the packaging film. The machine also comprises an upper welding unit, rotating around an upper rotation axis located above the advancement path, and a lower welding unit, rotating around a lower rotation axis located below the advancement path. In the embodiments described here, the upper axis of rotation and the lower axis of rotation are substantially parallel to each other and can be oriented substantially at 90 ° with respect to the direction of advancement of the products along the path of advancement. Each welding group comprises at least one respective welding bar, ie a first upper welding bar and a first lower welding bar, respectively for the upper welding group and for the lower welding group.

In the embodiments described here, the upper welding group is equipped with a translation movement orthogonal to the upper axis of rotation. Furthermore, in the embodiments described here, the lower welding unit is also equipped with a translation movement orthogonal to the lower axis of rotation. The translation movement of the upper welding group, the translation movement of the lower welding group, the rotation of the upper welding group and the rotation of the lower welding group are synchronized, combined and coordinated, so that the bar welding upper and lower welding bar each move along a respective closed trajectory. Each closed trajectory comprises a respective rectilinear portion parallel to the path of advancement of the products. The two rectilinear portions are substantially coincident, in the sense that the first upper welding bar and the first lower welding bar substantially travel the same trajectory portion. Their movement is simultaneous, i.e. the two coincident rectilinear trajectory portions are traversed by the first upper welding bar and the first lower salting bar at the same time.

Along the straight portion, the upper welding bar and the lower welding bar are pressed against each other. The rectilinear portion of each closed trajectory made by the upper sealing bar and the lower sealing bar is that portion along which the welding bars coupled together advance together with the flow of products or articles to be packaged, arranging themselves between the groups of ordered articles consecutive. Along this rectilinear portion of the trajectory the welding bars perform the cutting and welding of the tubular material in plastic film so as to complete and separate two consecutive packs of groups of items from each other.

In the embodiments described here, each welding bar extends longitudinally in a direction parallel to the upper axis of rotation and the lower axis of rotation, respectively. That is, each welding bar has a longitudinal development parallel to the rotation axis of the respective welding group to which the welding bar belongs.

To increase the hourly production, in some advantageous embodiments the upper welding group and the lower welding group each have more than one welding bar. For example, the upper welding assembly may comprise a second upper welding bar. Similarly, the lower welding assembly can comprise a second lower welding bar. In advantageous embodiments, the first upper welding bar and the second upper welding bar can be offset by 180 ° with respect to the upper axis of rotation. Similarly, the first lower welding bar and the second lower welding bar can be offset by 180 ° with respect to the lower axis of rotation. The possibility is not ruled out that each weld group includes more than two weld bars, such as three weld bars or four weld bars. Preferably, the welding bars are distributed according to substantially equal angles around the rotation axis, respectively upper and lower, of the two upper and lower welding groups.

Since each welding bar is carried by a welding unit which rotates around a respective axis of rotation, in advantageous embodiments each welding bar is combined with a mechanism which imparts to it a rotational motion opposite to the rotational motion of the respective welding unit, so that the sum of the two rotational motions gives rise to a translation motion. In particular, for each welding bar, a mechanism can be provided which gives the welding bar a rotational motion opposite to the overall one of the welding unit around the respective axis of rotation, at least along the rectilinear section of the respective closed trajectory. . In this way, each welding bar of both the lower welding group and the upper welding group moves in a translational rectilinear motion along the rectilinear portion of the respective closed trajectory.

In advantageous embodiments, the aforementioned mechanism is configured in such a way as to impart to the respective welding bar a translation motion along the entire closed trajectory traveled by it.

The various movements of rotation and translation of the upper welding group and of the lower welding group, as well as the movements of the welding bar, can be obtained with various possible combinations of motors and transmission members. In some embodiments, the upper welding group comprises a first motor to drive the rotation movement around the upper rotation axis, and a second motor to drive the translation movement of the welding group orthogonally to the respective rotation axis. Similarly, the lower welding group can comprise a first motor to drive the rotation movement around the lower rotation axis and a second motor to drive the translation movement of the lower welding group orthogonally to the lower rotation axis. In a configuration of this type it is therefore possible to provide four distinct motors to control the rotation and translation movements of the two welding units.

To limit the number of motors, reduce the cost and complexity of the machine, and / or to simplify the control of the servomechanisms, in some embodiments it is possible to provide a first common motor, which drives the rotation movement of the upper welding unit. around the upper axis of rotation and the rotation movement of the lower welding unit around the lower axis of rotation. Furthermore, a second motor can be provided to drive the translation movement of the upper welding unit, and a third motor to drive the translation movement of the lower welding unit.

Regardless of the number of motors used, the machine can include a programmable control unit that synchronizes and coordinates the movement of the various motors and therefore of the mechanical parts controlled by them.

To support the weld bar (s), in some embodiments the upper weld assembly may comprise an upper support frame, on which the respective upper weld bar (s) are supported. Each upper welding bar is suitably provided with a rotation movement with respect to the upper support frame about a longitudinal axis, parallel to the longitudinal extension of the bar itself.

In some embodiments, the lower welding assembly comprises a lower support frame, on which the respective lower welding bar (s) are supported. Each lower welding bar is suitably provided with a rotational movement with respect to the lower support frame about a longitudinal axis, parallel to the longitudinal extension of the bar itself.

As will become clear from the following detailed description of embodiments illustrated in the accompanying drawings, each welding bar can actually be supported by a respective support frame at each end. Basically, each welding unit can therefore comprise at least one welding bar arranged and supported by two opposing frames, positioned laterally to the path of advancement on two sides of the machine. The two frames are equipped with synchronous translation and rotation movements. When a welding group has more than one welding bar, the two or more welding bars can be supported at their ends by the respective two frames, positioned on the sides of the feed path and equipped with synchronous translation and rotation movements.

In some embodiments, the upper welding unit can comprise an upper driving gear ring, driven in rotation by a motorization around the upper axis of rotation. The upper support frame can be constrained directly or indirectly to the upper sprocket so as to rotate integrally with the upper sprocket while remaining free to translate with respect to it in a direction orthogonal to the upper rotation axis.

In some embodiments, the lower welding group comprises a lower drive ring gear, driven in rotation by a motorization around the lower axis of rotation. The lower support frame can be linked directly or indirectly to the lower drive sprocket so as to rotate integrally with the lower sprocket while remaining free to translate with respect to it in a direction orthogonal to the lower rotation axis.

Both in the upper welding unit and in the lower welding unit, the mechanical connection between the driving ring gear and the frame can be obtained by means of a coupling comprising at least one slide or a shoe and a straight guide, connected respectively to the driving ring gear and to the frame, or vice versa. By means of the rectilinear guide, extending in a direction substantially at 90 ° with respect to the rotation axis, and the pad or slide, the rotation movement is transmitted from the driving sprocket to the support frame, while the latter is free to move along the rectilinear guide with respect to the rotation axis and the driving sprocket.

The motorization that drives the upper sprocket and the lower sprocket can be common, i.e. a single motor can rotate the lower sprocket and the upper sprocket. In other embodiments, the motorization can comprise two distinct motors, coordinated by a suitable electronic control unit.

When the upper welding assembly and / or the lower welding assembly comprise two opposed support frames, placed on the sides of the path of advancement, each welding assembly can comprise two opposed driving sprockets, each constrained to the respective support frame in the manner Indicated above. The two opposing driving toothed crowns of a welding unit, which are substantially coaxial to each other, can receive movement for example from a single drive shaft, on which respective pinions are keyed and which extends transversely to the path of advancement.

To transmit the translation movement, the upper welding unit can comprise an upper toothed wheel for controlling the translation movement, located coaxially to the upper drive toothed crown. The lower welding group can comprise a lower toothed wheel for controlling the translation movement of the lower welding group, located coaxially to the lower driving toothed crown. The upper toothed wheel for controlling the translation movement can be made to rotate, with an alternating rotation movement, by a motor, which can be the same as that used for the lower toothed wheel for controlling the translation movement. In some embodiments, as described below, however, two separate motors are preferably used, coordinated by a control unit, to provide the rotation movement to the two toothed wheels, respectively upper and lower, which control the translation motion of the respective welding group.

When an upper and / or lower welding unit comprises two opposed supporting frames of the relative welding bars, two toothed wheels for controlling the translation movement can be conveniently provided for each welding unit, which are coaxial and positioned (similar to support frames) on opposite sides of the travel path. A shaft transversal to the path of advancement can be used to transmit motion simultaneously to the two coaxial toothed wheels, for example by means of pinions keyed to it.

In some embodiments, in order to transform the reciprocating rotation movement of the upper and / or lower toothed wheel for controlling the translation movement of the upper and / or lower welding unit, a respective open belt can be provided, i.e. comprising two ends. The open belt is preferably a toothed belt. Instead of a belt, another open flexible member may be provided, for example a chain. In this case, the sprocket for controlling the translation movement is a sprocket for a chain. In advantageous embodiments, the two ends of each open flexible member can be constrained in two opposite points, with respect to the upper axis of rotation, of the respective support frame of the upper welding group and of the support frame of the lower welding group.

To impose on the upper welding bar (s) a rotational movement opposite to the rotational movement of the upper welding unit, i.e. of the upper support frame of the unit itself, the upper welding unit can comprise an upper stationary gear wheel, coaxial to the crown upper drive gear. A mechanical transmission connected to each upper welding bar can cooperate with the upper stationary gear.

In order to impose a rotational movement to the lower welding bar (s) opposite to the rotational movement of the lower welding assembly, i.e. of the lower support frame of the assembly itself, the lower welding assembly can comprise a lower stationary gear wheel, coaxial to the crown lower drive toothed, with which a mechanical transmission connected to each lower welding bar can cooperate.

The mechanical transmission can be configured to transmit to each welding bar a rotation movement, around an axis parallel to the longitudinal extension of the bar, equal and opposite to the rotation movement of the respective support frame.

In advantageous embodiments, the mechanical transmission comprises a toothed wheel which meshes with the stationary toothed wheel and rolls along it. The toothed wheel can be an idle toothed wheel, which in turn meshes with a further toothed wheel, constrained, for example by means of a belt, to the welding bar. The stationary sprocket, idle sprocket and further sprocket form a gear train. The further toothed wheel can be dragged in rotation around the rotation axis of the respective welding group, thanks to a constraint, for example through an articulated arm, between the welding bar a shaft supporting the further toothed wheel. The further toothed wheel and the idle wheel can be rotatably supported on a rotating support, which rotates around the rotation axis, respectively upper or lower, of the respective welding group.

In practice, each mechanical transmission can comprise, for each welding bar, a train of gears, the first of which meshes with the stationary toothed wheel, and the last of which transmits the rotation motion to a continuous flexible member, conveyed around to a first pulley coaxial and torsionally coupled to it, and around a second pulley torsionally constrained to the respective welding bar. In the embodiments described here, each gear train can be supported by a member rotating around the rotation axis of the respective welding unit, and constrained to the respective support frame, for example by an oscillating arm.

When a welding assembly comprises two opposed welding bar support frames, the above described mechanical transmission can be duplicated for both frames. This, however, is not necessary and, in particularly advantageous embodiments, the mechanical transmission which transmits to the welding bar the rotational motion opposite to the overall rotational motion of the welding assembly, i.e. of its support frame, can be provided only on one frame, that is only on one side of the machine, and not on the opposite side.

In advantageous embodiments, the machine comprises a conveyor for the advancement of the products along the path of advancement.

In advantageous embodiments, adjustment organs can be provided configured in such a way as to adjust the distance of the conveyor with respect to the upper axis of rotation and the lower axis of rotation of the upper welding group and the lower welding group, respectively. In this way it is possible to adjust the reciprocal position of the conveyor and of the rotation axes according to the vertical dimension of the packages to be produced. For example, it may be envisaged to adjust the reciprocal position of the upper rotation axis, the lower rotation axis and the conveyor, so that the center line of the package is always equidistant with respect to the upper and lower rotation axes. For this purpose, the height of the conveyor can be adjusted with respect to the load-bearing structure on which the upper welding unit and the lower welding unit are arranged. In other currently preferred embodiments, the height of the conveyor can be fixed with respect to the load-bearing structure, while the upper welding unit and the lower welding unit are integrally adjustable so as to modify their height with respect to the load-bearing structure and, consequently, with respect to the position of the conveyor.

In advantageous embodiments, each upper welding bar and each lower welding bar is equipped with sealing members, for example in the form of electric resistors. Each upper welding bar and each lower welding bar can comprise for example two welding resistances side by side, extending parallel to the longitudinal extension of the respective welding bar. A suitable rotating manifold can be provided to supply electrical energy to the resistances of the welding bars.

Each welding bar of at least one of the upper and lower welding units can be equipped with a cutting blade. Each cutting blade can be equipped with a servo-drive mechanism, which controls the extraction and retraction of the cutting blade with respect to a housing seat.

The servo-mechanism can be, for example, of the electromechanical, pneumatic or hydraulic type. A suitable rotating manifold can be provided to supply the necessary power (electric, pneumatic or hydraulic) to the respective welding bar.

For example, each upper welding bar can be equipped with a cutting blade. Vice versa, the welding bars of the other welding group, for example of the lower welding group, can have no cutting blade and can each have, for example, a stationary counter-blade, cooperating with the cutting blade of a respective bar. welding top. The inverse arrangement is not excluded, with cutting blades applied to the lower welding bars and stationary counter-blades associated with the upper welding bars.

Each cutting blade can be equipped with an extraction and retraction movement with respect to a seat made inside the respective welding bar and can extend longitudinally according to the longitudinal development of the welding bar. Conversely, the counter blade can be stationary and can be formed by a channel. Preferably, the blade and the counter-blade are each arranged between two parallel electrical resistances of the respective welding bar.

Brief description of the drawings

The invention will be better understood by following the description and the attached drawings, which illustrate an exemplary and non-limiting embodiment of the invention. More specifically, in the drawing they show:

Fig. 1 is a schematic view of groups of products within a tubular of plastic film, which advance along a path of advancement;

Fig. 2 two packs of groups of products obtained with a cutting-welding machine described here;

Fig. 3 is a sequence schematically illustrating the operation of the welding bars of the cutting-welding machine described here;

Fig. 4 is an enlargement of phase C of the sequence of Fig. 3;

Fig. 5 is an enlargement of phase D of the sequence of Fig. 3;

Fig. 6 is a partial sectional view of the cutting-sealing machine according to a plane orthogonal to the direction of advancement of the products to be packaged; Figs. 7 and 8 lateral views according to VII-VII and VIII-VIII of Fig. 6;

Fig. 9 is an overlap of the mechanical members illustrated separately in the previous Figs. 7 and 8;

Fig. 10 is an axonometric view of the members of Fig. 9;

Fig. 11 is a view of a detail of the transmission members;

Figs. 12A-12D enlargements of the details indicated with XIIA, ΧΠΒ, XIIC, XTID in Fig. 6;

Fig. 13 is an axonometric view of the members for moving the welding bars, with parts removed;

Fig. 14 is a further axonometric view of the members for moving the welding bars, with parts removed;

Fig. 15 is a sectional axonometric view of the motion transmission members;

Figs. 16 and 17 axonometric views of the mechanical transmission members on the side of the cutting-welding machine opposite to the side on which the members of Figs. 7, 8 and 9.

Detailed description of an embodiment

The following detailed description of exemplary embodiments refers to the accompanying drawings. The same reference numerals in different drawings identify the same or similar elements. Furthermore, the drawings are not necessarily to scale. The following detailed description does not limit the invention. Rather, the scope of the invention is defined by the attached claims.

Reference in the description to "an embodiment" or "the embodiment" or "some embodiment" means that a particular feature, structure or element described in connection with an embodiment is included in at least one embodiment of the described object. Therefore the phrase "in an embodiment" or "in the embodiment" or "in some embodiment" used in the description does not necessarily refer to the same or the same embodiments. Furthermore, the particular features, structures or elements can be combined in any suitable way in one or more embodiments.

For a better understanding of the operation of the cutting-welding machine described below in detail, with initial reference to Figs. 1 to 5 will initially describe a welding and cutting cycle of a tubular plastic film in which ordered groups of products are packaged. The products can be rolls of tissue paper, such as toilet paper, kitchen paper or the like. In other embodiments the products can be packs of napkins, handkerchiefs or other manufactured articles, for example made of tissue paper. The products can also in turn consist of multiple packages, each containing a plurality of products, for example a plurality of tissue paper rolls, such as toilet paper, kitchen paper or the like.

The groups of products to be packaged are formed in a station of a production line, not object of the present description and not represented in the drawings. In Fig. 1 two groups of products are shown, schematically indicated with 1, which are located inside a tubular of plastic film 3. The methods and machines for grouping the products and inserting them in a tubular of plastic film are per themselves known and are not described here. The groups of products 1 advance according to the arrow 4 along an advancement path indicated as a whole by 5. The numeral 7 schematically indicates a conveyor, for example a conveyor belt, or a conveyor belt or a plurality of transport belts parallel to each other.

By means of the cutting-sealing machine described in detail below, the individual groups 1 of products are enclosed and packaged in portions of plastic film obtained by cutting and welding the tubular plastic film 3. In Fig. 2 the groups of products are shown ordered 1, after cutting and transversal welding of the plastic film tubular 3 into individual portions of tubular 8, welded at 9 and 10.

Fig. 3 schematically illustrates a five-step sequence of the welding and cutting process of the continuous tubular plastic film 3 to obtain the two packages of products enclosed in the portions of tubular plastic film 8. Fig. 3 schematically illustrates the sealing groups hereinafter generically referred to as the upper welding group II and lower welding group 13, forming part of the cutting-welding machine. In the sequence of Fig. 3 of such welding units, in reality only the welding bars and the trajectories performed by the welding bars during the cutting and welding cycle are shown. Mechanical components of the welding units will be described later.

More specifically, in some embodiments, as schematically illustrated in the attached drawing, the upper welding unit 11 comprises a first upper welding bar 15 and a second upper welding bar 17. The trajectory followed by each of the upper welding bars 15 and 17 during the operation of the cutting-welding machine.

In some embodiments, as schematically illustrated in the attached drawing, the lower welding assembly 13 comprises a first lower welding bar 19 and a second lower welding bar 21. T2 indicates the trajectory followed by each of the lower welding bars 19 and 21 during the operation of the cutting-welding machine.

The upper sealing unit 11 rotates around an upper rotation axis 23, located above the path 5 of the products to be packaged. The lower welding assembly 13 rotates around a lower rotation axis 25, located under the advancement path 5.

In some embodiments, the upper welding bars 15 and 17 are positioned offset from each other by 180 ° with respect to the axis of rotation 23 of the upper welding assembly 11, while the lower welding bars 19 and 21 are arranged offset from each other. 180 ° with respect to the rotation axis 25 of the lower welding unit 13.

The sequence (A) - (E) in Fig. 3 shows successive positions assumed by the pair of sealing bars 15 and 19 to carry out the welding and cutting of the tubular plastic film 3 between the groups 1 of products shown in the figure.

In position (A) the product groups 1 are spaced apart by a distance D equal to the height H of the product groups 1 added to the width of the sealing bar, i.e. the size of each sealing bar in the direction of advance 4 of the products 1 to be packaged. In this phase the groups of products 1 advance at a constant speed according to the arrow 4. The sealing bars move along the respective trajectories T1 and T2 according to the arrows indicated in the drawing.

As will be described in greater detail below, each welding bar moves along its own trajectory with a translational motion, while a frame that supports them moves with a combined motion comprising a rotation around the respective axis 23 or 25, and a translation orthogonal to the respective rotation axis 23 or 25.

More specifically, as can be seen from the sequence of Fig. 3, each welding bar 15, 17, 19 and 21 moves translationally, in the sense that it always remains parallel to itself along the entire respective closed trajectory T1 and T2 . Furthermore, each pair of welding bars 15, 17 and 19, 21 respectively moves in a direction orthogonal to the respective rotation axis 23 or 25, so that while one welding bar approaches the rotation axis, the other moves away from it. , the distance between the two welding bars of the same welding group remaining constant.

As can be seen in the sequence of Fig. 3, each trajectory T1 and T2 has a straight section. The rectilinear sections of the two trajectories Tl, T2 are mutually coincident and parallel to the feed direction 4 of the products 1 along the feed path 5. Along this portion of the rectilinear trajectory an upper welding bar cooperates with a corresponding lower welding bar to carry out the welding and cutting of the tubular plastic film 3.

Fig. 3 (B) shows the instant in which the upper welding bar 15 and the lower welding bar 19 begin to move along the common rectilinear portion of the trajectories T1 and T2. Along the common rectilinear portion of the trajectories T1 and T2 the two sealing bars 15 and 19 cooperate with each other to carry out the welding and cutting of the plastic film. Along this portion of trajectory the two sealing bars 15, 19 compress the plastic film while the group of products 1 further upstream continues to advance at a substantially constant speed.

As can be seen by comparing Figs. 3 (A) and 3 (B), Γ mutual approach of the sealing bars 15,19 causes a retraction of the plastic film tube 3. The retraction of the plastic film tube causes in turn a dragging behind the product group 1 further downstream which therefore approaches the product group 1 further upstream. The backward movement of the product group 1 further downstream towards the product group 1 further upstream, while the latter advances at a constant speed, is such as to bring the product groups 1 to a mutual distance substantially corresponding to the transverse dimension of the welding bars i.e. to the size of these bars in the direction of advance 4.

Starting from Fig. 3 (B) the welding bars 15, 19 begin to advance along the common straight section of the trajectories T1 and T2 pressed against each other with a force sufficient to cause the welding, thanks to the presence of electric resistors or other heating members present on both welding bars 15, 19, or on at least one of them. The two welding bars 15, 19 advance along the straight section of common trajectory at the same speed of advancement of the two groups of products 1

Figs. 3 (C) and 3 (D) show the displacement of the welding bars 15, 19 along the common rectilinear portion of the two trajectories T1 and T2. During this movement, in addition to sealing the film thanks to the electrical resistance present in at least one of the sealing bars 15, 19, the plastic film is also cut, so as to separate the two groups of adjacent products 1 from each other. The cut is carried out, in a per se known way, between two welding lines side by side, by means of blade members, for example an extractable and retractable blade contained in the upper welding bar 15, or in the lower welding bar, and a counter- fixed blade, made in the lower welding bar 19, or in the upper welding bar In the passage from Fig. 3 (D) to Fig. 4 (E), the product group 1 downstream is pushed forward and distanced from the products 1 upstream due to the acceleration of the welding bars 15, 19 which have carried out the welding and cutting. The motion of the welding bars continues until the welding bars 17, 21 are in the position previously assumed by the welding bars 15, 19 in Fig. 3 (A), to start a new welding cycle.

As can be seen from the sequence illustrated in Fig. 3, during their movement along the trajectories T1 and T2 the upper welding bars 15, 17 and the lower welding bars 19, 21, in addition to moving translationally, each remaining parallel to itself, and in addition to moving along the closed path defined by the trajectories Tl, T2 around the rotation axis 23 or 25, they have a translation movement that leads them to approach and move away cyclically with respect to the respective rotation axis 23, 25. As will be clarified below, in some embodiments the pair of upper welding bars 15, 17 are constrained to each other and kept in opposite positions with respect to the axis of rotation 23, so that when the first upper welding bar 15 approaches the axis of rotation 23, the second upper welding bar 17 moves away from the axis of rotation 23 and vice versa. Similar movement is provided for the lower welding bars 19, 21 with respect to the rotation axis 25.

Figs. 4 and 5 show enlargements of the steps indicated in Figs. 3 (C) and 3 (D), respectively. In Figs. 4 and 5 schematically show, for the upper welding unit II and for the lower welding unit 13, a respective upper support frame 31 and a respective lower support frame 33. The two support frames 31 and 33 rotate around the rotation axes 23 and 25 and are also each equipped with a translation movement according to the arrows F31 and F33 orthogonal to the corresponding rotation axis 23, 25. The frame 31 carries the upper welding bars 15, 17, while the support frame lower 33 carries the lower welding bars 19, 21. The combined movement of rotation and translation of the support frames 31 and 33 allows the welding bars 15, 17, 19 and 21 to be moved along the trajectories T1 and T2 described above.

The translation movement according to the double arrows F31 and F33 of the two support frames 31 and 33 can be obtained by means of a mechanism better described in the following with reference to the following figures, and partly schematically represented already in Figs. 4 and 5.

With regard to the upper welding unit 11, the mechanism that controls the translation of the frame 31 according to the double arrow F31 may include an upper toothed wheel 35 which rotates in a controlled manner around the axis 23, alternately clockwise and counterclockwise. An open toothed belt 37 which comprises two ends 37A and 37B is driven around the upper toothed wheel 35. The ends 37A, 37B are anchored in two spaced and opposite points of the frame 31. Return wheels 39, 41 define the arc of contact of the open toothed belt 37 with the upper toothed wheel 35. Rotating the upper toothed wheel 35 in one direction or in the other, around the axis of rotation 23, a translation movement of the frame 31 with respect to the axis 23 is caused.

A substantially identical arrangement can be provided for the lower welding group 13. 43 indicates a lower toothed wheel coaxial to the rotation axis 25 and rotating alternately clockwise and counterclockwise around this rotation axis. The reference number 45 indicates an open toothed belt, whose ends 45A and 45B are fixed in two opposite and spaced points to the frame 23. The reference wheels of the toothed belt 45 are indicated by 47 and 49.

Fig. 6 shows a view and partial section of the cutting-welding machine, indicated as a whole with 50, of which the mechanical members described up to now belong. The section plane of Fig. 6 is orthogonal to the direction 4 of advancement of the products 1 to be packaged along the advancement path 5 and contains the rotation axes 23, 25.

In Fig. 6, in particular, the first upper welding bar 15, the second upper welding bar 17, the first lower welding bar 19 and the second lower welding bar 21 are visible. For a more exhaustive representation, the welding bars they are shown in the arrangement of Fig. 3 (C), ie essentially in the position in which the welding bars 15, 17, 19, 21 are coplanar on a vertical plane, containing the rotation axes 23 and 25.

Fig. 6 also shows the upper and lower branches of the conveyor 7 (figure 1) on which the groups of products 1 to be packaged advance, not shown. The conveyor 7 is suitably interrupted along the advancement path 5 to allow the passage of the lower welding bar 19, 21.

The cutting-sealing machine 50 comprises two sides 51 and 53 placed at the sides of the advancement path 5 of the groups of products 1 to be packaged. The sealing bars 15, 17, 19, 21 move along the trajectories T1 and T2 within the space delimited between the two sides 51 and 53. In consideration of the width of the packages and therefore the length of the sealing bars (ie of their longitudinal development, transversely to the direction of advance 4 of the products 1), the sealing bars can be supported by both ends. For this purpose, respective supporting frames for the welding bars are associated with the two sides 51 and 53. The frames 31 and 33 illustrated in Fig. 4 and 5 can be placed on the side 51 or on the side 53, it being understood that on the opposite side there will be a similar arrangement of two frames similar to those indicated with 31 and 33.

Similarly, substantially specular mechanical members can be arranged on the two sides 51 and 53 for transmitting the rotation and translation motion to the welding bars. In advantageous embodiments, the motors for controlling the various movements are arranged on one of the two sides, for example on the side 51, while the motor shafts transmit the rotational movements to the opposite side 53.

Specific reference will be made hereinafter to the parts placed on side 51.

The motion handling and transmission members located on the side 51 are shown in Figs. 6 to 15. The motion transmission members associated with the upper welding group 11 will be initially illustrated below. The motion transmission members to the lower welding group 13 are substantially the same or equivalent.

As can be seen in particular in Figs. 6, 10, 12 and 15, the toothed wheel 35 around which the open belt 37 is driven is integral with a cylindrical body 35A, or made integrally with it. The cylindrical body 35A is coaxial with the upper rotation axis 23. The cylindrical body 35A is in turn integral with a toothed crown 55. The toothed crown 55 is driven in rotation by an electronically controlled electric motor 57 (see in particular Fig . 10). A double toothed belt 59, ie with toothing on both faces, is driven around a pinion 58 of the motor 57 and around the toothed crown 55. The electric motor 57 rotates clockwise or counterclockwise, depending on the phases of the cycle. welding and cutting, to cause, in the manner already described, the translation of the frame 31 according to the arrow F31 (Fig. 5).

A sprocket 61 is concentric with the cylindrical body 35A, the crown gear 55 and the toothed wheel 35. The latter can be concentric with a stationary cylindrical body 63 integral with the side 51 and concentric with the rotation axis 23. Bearings 65, 67 and 69 (see in particular in Fig. 12) can be interposed between the cylindrical body 35A, the stationary cylindrical body 63 and the sprocket 61. In this way the sprocket 35 and the sprocket 61 can rotate the one independently of the other around the same axis of rotation 23, as can be seen in particular in Figs. 10 and 12.

A double toothed belt 71, ie with toothing on both faces, can be driven around the driving toothed crown 61. The toothed belt 71 can take motion from a shaft 73 (see in particular Figs. 7, 8, 9 and 10). The shaft 73 can be rotated by its own coaxial motor or, as shown in the drawing, by means of a toothed belt 75, in turn driven by a motor 77 (see in particular Fig. 10). The motor 77 rotates a shaft 78 on which a toothed pulley 79 is keyed, which supplies the motion to the toothed belt 75. The shaft 78 can extend from the side 51 to the side 53 where, with a similar arrangement, the motion with a driving ring gear specular to the driving ring gear 61, so as to have a uniform distribution of the driving torque on the two sides.

With this arrangement of mechanical members, the pair of upper welding bars 15 and 17 and the support frame 31 are provided with a rotation movement around the rotation axis 23 and a translation movement perpendicular to said axis, according to a direction parallel to the plane on which the two welding bars 15, 17 are located. The electric motor 57, rotating alternately clockwise and counterclockwise, rotates the ring gear 55 and, integral with it, the toothed wheel 35. The rotation in one direction or in the other of the toothed wheel 35 causes, due to the constraint provided by the open toothed belt 37, the translation movement according to the double arrow F31 of the frame 31 orthogonal to the rotation axis 23. The translation movement (F31) is coordinated with the rotational movement of the frame 31 about the axis of rotation 23. This rotational movement is imparted by the motor 77 through the belt 75, the driven shaft 73, the belt 71 and the drive ring gear 61.

The sprocket 61 is constrained to the support frame 31 in such a way as to transmit to the support frame 31 the rotational motion around the axis 23, while at the same time allowing the support frame 31 to move with reciprocating translational motion according to the arrow F31 . This constraint can be obtained, for example, by means of guide shoes or carriages 81 rigidly connected to the sprocket 61 and shown in particular in Fig. 14. The guide shoes 81 are slidingly engaged in guides 83 integral with the support frame 31 (see again Fig. 14 and Fig. 10). This coupling between shoes 81 and guides 83 allows to transmit to the support frame 31 the motion of rotation around the rotation axis 23, provided by the driving ring gear 61, at the same time allowing the translation of the support frame 31 orthogonally to the axis of rotation 23 with respect to the driving toothed crown 61.

Similar movements are imparted to the lower support frame 33, which carries the lower welding bars 19 and 21, with the same arrangement of mechanical members. More specifically (see for example Figs. 8 to 10 and 12B) the lower toothed wheel 43 can be integral with a cylindrical body 43A, which is in turn probed to a toothed crown 87, which provides the reciprocating rotation motion to the toothed wheel 43, in a similar way to that provided for the toothed crown 55 with respect to the toothed wheel 35. The rotation motion in alternating directions to the toothed crown 87 is provided by an electronically controlled electric motor 89 through a double toothed belt 91, i.e. with toothing on both faces, equivalent to toothed belt 59.

Coaxially to the cylindrical body 43A there is a lower drive sprocket 93, having functions equivalent to those of the sprocket 61. In the illustrated embodiment, the lower sprocket 93 is driven by a double toothed belt 95, i.e. with both toothed faces, which takes its motion from a driven shaft 97. The members 95 and 97 are equivalent to the members 71 and 73. The driven shaft 97 can receive motion from its own independent motor, equivalent to the motor 77 which may possibly be coaxial to shaft 73. In other embodiments, as illustrated in the attached drawing, shaft 97 can receive motion from the same motor 77, through the same belt 75 which transmits motion to the driven shaft 73. In fact, the movements of rotation around the rotation axes 23 and 25 of the two upper 11 and lower 13 welding units are synchronized and can therefore be controlled by the same motor 77.

As previously illustrated with reference to the sequence of Fig. 3, during the operation of the cutting-welding machine 50 the welding bars 15, 17, 19 and 21 move while remaining parallel to themselves, i.e. they move translationally while performing the respective trajectories T1 and T2. The welding bars are supported on both ends by the support frames 31, 33 which rotate around the respective axes of rotation 23 and 25. More particularly on the side 51, as described above, the upper welding bars 15 and 17 are supported by the frame 31 rotating around the axis 23, and the lower welding bars 19 and 21 are supported by the frame 33 rotating around the axis 25.

In order to keep each welding bar parallel to itself, and therefore to impose a translation rather than a rotational movement on each welding bar 15, 17, 19, 21, it can be provided to add to the rotary motion of the respective support frame 31 or 33, an opposed rotational motion in the opposite direction to the welding bar with respect to the frame that supports it. For this purpose, in some embodiments a gear mechanism is provided, described below in greater detail as regards the upper welding unit 11 with particular reference to Figs. 11, 12A, 13, 14 and 15. This mechanism is arranged only on the side of the side 51 and not on the side of the side 53. The mechanism in question is substantially the same for the upper 11 and lower 13 welding units. only the mechanism relating to the upper welding unit 11 is described.

As far as the upper welding unit 11 is concerned, the mechanism comprises an upper stationary gear wheel 101 coaxial to the driving gear 61, the gear wheel 35 and the crown gear 55. Two idle gear wheels 103 mesh with the upper stationary gear wheel 101 and 105 housed inside the respective support frame 31. The two idle toothed wheels 103 and 105 are supported, as better illustrated in Figs. 13 and 14, on two distinct the rotating supports 107 and 109 also visible in Fig. 12A. For a clearer representation of this mechanism, in Fig. 13 the support frame 31 has been omitted and the rotating supports 107 and 109 and the gears associated with them are shown, in particular the idle gear wheel 105 supported by the rotating support 109 and the idle toothed wheel 103 supported by the rotating support 107. The rotating supports 107 and 109 rotate about the axis of rotation 23. The idle wheel 103 meshes, in addition to the upper stationary toothed wheel 101, with a further toothed wheel 111. Also the further toothed wheel 111 is supported rotatably by the rotating support 107. Similarly, the idle toothed wheel 105 meshes, as well as with the upper stationary toothed wheel 101, with a further toothed wheel 113 supported by the rotating support 109.

The rotating supports 107 and 109 are guided, in their rotation movement, on annular guides 115 (see in particular Figs. 13 and 15) and 117 (see Fig. 15) respectively. The rotating supports 107 and 109 are engaged with the respective annular guides 115 and 117 by means of grooved rollers 121 or other suitable members. The annular guide 115 can be fixed to a plate 123, which in turn is constrained to the upper stationary toothed wheel 101. The annular guide 117 can be constrained to the toothed wheel 35.

An oscillating arm 131 is articulated to the rotating support 107. More particularly, the oscillating arm 131 is articulated around the axis of a shaft 130. The shaft 130 is substantially parallel to the axis of rotation 23 and the wheel is keyed on it. toothed 111. The oscillating arm 131 is also articulated around an axis of rotation of the upper welding bar 17. With reference to Figs. 13 and 14, 17A indicates an end support of the upper welding bar 17, with which the welding bar 17 is rotatably supported on the support frame 31. The welding bar 17 is equipped with a shaft 17B, inserted in the support 17A. A pulley 133 is keyed on the shaft 17B, around which a belt 135 is returned, which is also returned around a further pulley 137, keyed on the shaft 130. With this arrangement, the welding bar 17 is constrained to the support rotating 107 and receives the rotational motion transmitted by the toothed wheel 111 through the pulley 137, the belt 135 and the pulley 133.

The operation of the mechanism described above is as follows. When the support frame 31 rotates around the axis 23, the shaft 17B of the welding bar 17 is rotated together with the support frame 31 around the upper rotation axis 23. The rotating support 107 is also dragged in rotation about the rotation axis 23 due to the effect of the mechanical connection provided by the arm 131. Consequently, the idle toothed wheel 103 rolls around the upper stationary toothed wheel 101, with which it meshes. The rotation of the idle toothed wheel 103 is transmitted to the toothed wheel 111 which forms, together with the idle toothed wheel 103 and the stationary toothed wheel 101, a train of gears constituting an epicyclic wheel. Consequently, the toothed wheel 111 rotates and transmits the rotation movement to the shaft 17B of the upper welding bar 17, through the belt 135 and the pulleys 137, 133. The motion transmitted by the belt 131 is added to the rotation motion provided by the support 31 around the upper rotation axis 23. Since the two movements are in opposite directions, the welding bar 17 is dragged along the trajectory T1 with a translation motion without rotation, remaining parallel to itself.

An equivalent mechanism is provided for the other upper welding bar 15, as visible in Fig. 13. The other upper welding bar 15 is mounted on a shaft 15B mounted in a support 15A fixed on the frame 31. An arm 141, equivalent to the arm 131, mechanically connects the rotating support 109 to the shaft 15B and therefore to the frame 31, while a mechanical transmission with pulleys and belt 143, 145, 147 transmits the rotation motion from a shaft 140, corresponding to the shaft 130, to the shaft 15B when the rotating support 109 is driven into rotation by the support frame 31. The idle toothed wheel 105 rolls on the stationary toothed wheel 101 and transmits the rotation motion to the toothed wheel 113. This transmits it to the shaft 140 and from here, by means of the belt 145, the motion is transmitted to the shaft 15B. The rotation imposed by this kinematic transmission chain on the upper welding bar 15 cancels the rotation imposed by the support frame 31 rotating around the axis 23, so that the upper welding bar 15 moves translationally, remaining parallel to itself when it is moved along the trajectory T1 due to the movement of the support frame 31.

The same mechanism is provided for the lower welding unit 13, which has a lower stationary toothed wheel 151 (Fig. 12B), equivalent to the stationary toothed wheel 101, with which members substantially identical to those described above and indicated with the references 103 to 147, to impose on the two lower welding bars 19 and 21 a movement of simple translation instead of rotation when they are moved along the trajectory T2. In Fig. 12B these further components, which take their motion from the stationary toothed wheel 151 are indicated with the same reference numbers used for the corresponding components of the upper welding unit, illustrated in Figs. 11, 12A, 13 and 14.

Ultimately, with the above described kinematic mechanisms, the translation motion of the lower welding bars 19, 21 and the upper welding bars 15, 17 is obtained along the two closed trajectories T2 and T1 described with reference to Figs. 3 to 5.

By means of the shaft 78, the rotation movement of the motor 77 is transmitted to the side 53 where an arrangement of support frames 31, 33 can be provided, mirroring the one illustrated with reference to the side 51 to support the welding bars 15, 17, 19 and 21 at both their ends. A shaft 60 (Fig.10) can transmit the reciprocating rotation motion of the engine 57 to the side 53. A shaft 90 can be provided to transmit the reciprocating rotary motion of the engine 89 to the side 53.

On the side 53 there are mechanical members equivalent to those described above for the side 51, which transfer the movement from the shafts 78, 60, 90 to the frames equivalent to the support frames 31, 33 for supporting and moving the upper welding bars 15, 17 and lower welding bars 19, 21.

Figs. 16 and 17 show external axonometric views of the members relating to the lower 13 and upper 11 welding units, respectively. The same reference numbers used for the members of the side 51, increased by “200”, distinguish elements equivalent to those described above. These organs are not described again. Furthermore, 400, 402, 404, 406 indicate rotating distributors which supply electrical energy and a fluid under pressure to the upper welding bars 15, 17 and to the lower welding bars 19, 21, to heat electrical resistors and actuate blades. cutting, not described in detail and known to those skilled in the art, through which to carry out the welding and cutting of the plastic film 3.

To make the welding performed by the welding bars 15, 17, 19, 21 more efficient, pressure and thrust systems of the bars against each other can be provided, which act in the common straight section of the two trajectories T1 and T2 . In some embodiments, fixed cams 201 may be provided (see Figs. 6, 11) which extend for the length of the straight section of the aforementioned trajectories, and with which feeler rollers 203 carried near the ends of each bar cooperate. welding. The feeler rollers 203 can be connected to the welding bars with elastic thrust systems, so that the pressure of the cams 201 on the feeler rollers 203 causes an elastic thrust of the welding bars against each other.

Claims (13)

Cutting-welding machine Claims 1. A cutting-sealing machine (50) for sealing and cutting a packaging film (3) of product packages (1) wrapped in said film, comprising: - an advancement path (5) of the products (1) wrapped in the packaging film (3); - an upper welding unit (11), rotating around an upper rotation axis (23) placed above the advancement path (5), and comprising at least a first upper welding bar (15, 17); - a lower welding unit (13), rotating around a lower axis of rotation (25) placed under the advancement path (5), and comprising at least a first lower welding bar (19, 21); in which the upper welding group (11) is equipped with a translation movement (F31) orthogonal to the upper rotation axis (23); in which the lower welding group (13) is equipped with a translation movement (F33) orthogonal to the lower rotation axis (25); and in which the translation movement (F31) of the upper welding unit (11), the translation movement (F33) of the lower welding unit (13), the rotation of the upper welding unit (11) and the rotation of the unit lower welding bar (13) are synchronized and coordinated with each other, so that the upper welding bar (15; 17) and the lower welding bar (19; 21) each move along a respective closed trajectory (Tl, T2 ) comprising a rectilinear portion parallel to the path of advancement (5), along said rectilinear portion the upper welding bar (15; 17) and the lower welding bar (19; 21) being pressed against each other. 2. Cutting-welding machine (50) as per claim 1, in which the upper welding unit (11) comprises a second upper welding welding bar (17; 15) and the lower welding assembly (13) comprises a second lower welding bar (21; 19); in which the first upper welding bar (15) and the second upper welding bar (17) are offset by 180 ° with respect to the upper rotation axis (23); and in which the first lower welding bar (19) and the second lower welding bar (21) are offset by 180 ° with respect to the lower rotation axis (25). 3. Cutting-welding machine (50) as per claim 1 or 2, in which each welding bar (15, 17, 19, 21) is equipped with a rotation movement around a respective axis parallel to the welding bar with a opposite direction of rotation with respect to the direction of rotation of the corresponding welding unit (11; 13), so that each welding bar moves as a whole by a substantially translational motion along at least part of the closed trajectory (Tl; T2) and preferably along the entire trajectory closed. 4. Cutting-welding machine (50) according to one or more of the preceding claims, wherein the upper welding unit (11) comprises a first motor (77) to drive the rotation movement and a second motor (57) to drive the translation movement. 5. Cutting-welding machine (50) according to one or more of the preceding claims, wherein the lower welding unit (13) comprises a first motor (77) to drive the rotation movement and a second motor (89) to drive the translation movement. 6. Cutting-welding machine (50) according to one or more of the preceding claims, in which a first motor (77) drives the rotation movement of the upper welding unit (11) and of the lower welding unit (13), a second motor (57) drives the translation movement of the upper welding group (11), and a third motor (89) drives the translation movement of the lower welding group (13). 7. Cutting-welding machine (50) according to one or more of the preceding claims, in which the upper welding unit (11) comprises an upper support frame (31), on which the respective upper welding bars (15) are supported , 17); and in which the lower welding assembly (13) comprises a lower support frame (33), on which the respective lower welding bars (19, 21) are supported. 8. Cutting-welding machine (50) as per claim 7, in which the upper welding unit (11) comprises an upper driving toothed crown (61), rotated by a motor (75, 77, 71) around the upper axis of rotation (23); in which the upper support frame (31) is constrained to the upper driving ring gear (61) so as to rotate integrally with the upper driving ring gear (61) and translating with respect to it in a direction orthogonal to the upper rotation axis ( 23); in which the lower welding group (13) includes a lower drive sprocket (93), driven in rotation by a motor (77, 75, 95) around the lower axis of rotation (13); in which the lower support frame (33) is constrained to the lower drive sprocket (93) so as to rotate integrally with the lower sprocket and translate with respect to it in a direction orthogonal to the lower rotation axis (13). 9. Cutting-welding machine (50) as per claim 8, in which the upper welding unit (11) comprises an upper toothed wheel (35) for controlling the translation movement of the upper welding unit (11), coaxial to the crown upper drive toothed (61); and in which the lower welding assembly (13) comprises a lower toothed wheel (43) for controlling the translation movement of the lower welding assembly (12), coaxial to the lower drive toothed crown (93). 10. Cutting-welding machine (50) as per claim 9, in which a first flexible member (37) with two ends is conveyed around the upper toothed wheel (35) for controlling the translation movement of the upper welding unit (11) (37A, 37B) constrained in two opposite points, with respect to the upper axis of rotation (23), of the upper support frame (31); and in which a second flexible member (45) with two ends (45A, 45B) constrained in two opposite points, with respect to the 'lower axis of rotation (25), of the lower support frame (33). 11. Cutting-welding machine (50) according to one or more of claims 8 to 10, wherein the upper welding assembly (11) comprises an upper stationary gear wheel (101), coaxial to the upper driving gear (61), with which a mechanical transmission connected to each upper welding bar (15, 17) cooperates, the mechanical transmission being configured to transmit to each upper welding bar a rotation movement, about an axis parallel to its longitudinal development, equal and opposite to the rotational movement of the respective upper support frame (31); and in which the lower welding unit (13) comprises a lower stationary toothed wheel (151), coaxial to the lower drive ring gear (93), with which a mechanical transmission connected to each lower welding bar (17, 19) cooperates, the mechanical transmission being configured to transmit to each lower welding bar a rotation movement, about an axis parallel to its longitudinal extension, equal and opposite to the rotation movement of the respective lower support frame. 12. Cutting-welding machine (50) as per claim 11, in which each mechanical transmission comprises, for each welding bar (15, 17, 19, 21), a train of gears, the first (103, 105) of which meshes with the stationary toothed wheel (101; 151), and the last of which (111; 113) transmits the rotation motion to a continuous flexible member (135; 145), conveyed around a first pulley (137; 147) coaxial and torsionally coupled to it, and around a second pulley (133; 143) torsionally constrained to the respective welding bar (15; 17, 19, 21); and in which each gear train is supported by a support (107; 109) rotating around the rotation axis (23; 25) of the respective welding unit (11; 13), and constrained to the respective support frame (31; 33) by a swinging arm (131; 141). 13. Cutting-welding machine according to one or more of the preceding claims, comprising a conveyor (7) for the advancement of the products (1) along the advancement path (5), and in which the distance of the conveyor with respect to the axis the upper rotation axis (23) and the lower rotation axis (25) can be adjusted according to the vertical dimension of the product packs (1).