CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority from Italian patent application no. 102018000002271 filed on 31/01/2018, the entire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The invention relates to a unit to feed suction-held components in an automatic manufacturing machine.

This invention finds advantageous application in the feeding of components in an automatic manufacturing machine to manufacture hygiene absorbent articles, to which explicit reference will be made in the description below without loosing in generality. PRIOR ART

A known manufacturing machine to manufacture hygiene absorbent articles comprises a moving line for a continuous band of impermeable material (e.g. polyethylene), along which there are arranged a plurality of operating units, which feed the band, in a continuous manner, with the base components (such as, for example, the absorbent padding or a layer of nonwoven fabric permeable to liquids) and the accessories (such as, for example, elastic bands, faeces barriers and side wings), which define the absorbent article.

Each operating unit comprises a feeding unit provided with a main drum (usually hinged so as to rotate, with a continuous motion, around a central rotation axis), which supports a plurality of sucking holding heads, each designed to receive a corresponding component, which is separated from a continuous band by means of a crosswise cut. in an input station, each sucking holding head receives a corresponding component, which is still part of the continuous band (namely, is the final end of the continuous band) and is subsequently separated from the continuous band by means of a crosswise cut made by a cutting device arranged downstream of the input station. Downstream of the cutting device, each head can by rotated by 90° so as to change the orientation of the component. Finally, in an output station, each sucking holding head releases the corresponding component. In known feeding units, in order to convey the sucking holding heads, it is possible to use a transport system with directly operated linear electric motors, as described in patent application WO2017158572A1.

The transport system with linear electric motors described in patent application WO2017158572A1 has, for each sucking holding head, one single slide, which supports the holding head as it slides along a central guide. In particular, each slide is coupled to the guide thanks to four pair of idle wheels arranged perpendicularly to one another so as to ensure a crosswise containment of the slide relative to the guide and allow the slide to only slide along the guide. The pairs of wheels generally must be arranged at a close distance, so as to allow the slide to also slide along the parts of the guide having a reduced bending radius, thus covering sharp bends. As a consequence, the aforesaid slides usually are small-sized.

However, in the transport system with linear electric motor described in patent application WO2017158572A1, the inventors do not disclose how the necessary suction is generated in the sucking holding heads.

Document US2013270066 describes a feeding unit in which the sucking holding heads are each mounted on a respective slide provided with wheels. The slides are moved along a cam by a transporting drum, which is mechanically connected to the holding heads. Documents US5025910 and WO8805416 disclose a feeding unit in which the sucking holding heads are mechanically connected directly to a transporting drum, without the aid of slides provided with wheels.

DESCRIPTION OF THE INVENTION

The object of the invention is to provide a unit to feed suction-held components in an automatic manufacturing machine, which does not suffer from the drawbacks described above and, at the same time, is easy and economic to be manufactured.

According to the invention, there is provided a unit to feed suction-held components in an automatic manufacturing machine according to the appended claims.

The appended claims describe preferred embodiments of the invention and form an integral part of the description.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the accompanying drawings, which show some non-limiting embodiments thereof, wherein:

• figure 1 is a schematic front view of a unit to feed components of hygiene absorbent articles according to the invention;

• figure 2 is a simplified perspective view of part of the feeding unit of figure 1, wherein a movable equipment and part of a guide are highlighted

• figure 3 is a schematic perspective view of the feeding unit of figure 1 ;

• figure 4 is a side view of a movable equipment of the feeding unit of figure 1 ;

• figures 5 and 6 are an upper perspective view and a lower perspective view, respectively, of the movable equipment of figure 4;

• figure 7 is a perspective sectional view of part of the feeding unit of figure 1 by means of a plane perpendicular to the conveying direction of a movable equipment;

• figure 8 is a side view of a different embodiment of the movable equipment of figure

4;

• figures 9 and 10 are an upper perspective view and a lower perspective view, respectively, of the movable equipment of figure 8; and

• figure 11 is a schematic front view of the feeding unit of figure 1 with, highlighted, a rotary vacuum chamber connected to the movable equipments in a pneumatic manner.

PREFERRED EMBODIMENTS OF THE INVENTION

In figure 1, number 1 indicates, as a whole, a feeding unit 1 to feed a component 2 of a hygiene absorbent article. The feeding unit 1 is part of an automatic manufacturing machine to manufacture absorbent hygiene articles.

In the preferred and non-limiting embodiment shown in figure 1, each component 2 is obtained from a continuous band 3 (unwound from a reel, which is not shown herein) by means of a crosswise cut of the continuous band 3; namely, the continuous band 3 is cyclically cut crosswise so as to separate, in succession, the single components 2 from the continuous band 3. According to a different embodiment which is not shown herein, the feeding unit 1 singularly receives the components 2, which, hence, are not separated from the continuous band 3.

The feeding unit 1 comprises a plurality of sucking holding heads 4, which are each designed to receive and hold a corresponding component 2. Furthermore, the feeding unit 1 comprises a conveyor 5, which supports the sucking holding heads 4 and cyclically moves each sucking holding head 4 along an application path P (shown in figure 1).

The application path P goes through an input station S l, where the sucking holding head 4 receives a corresponding component 2, and through an output station S2, where the sucking holding head 4 releases the component 2 to a subsequent device 6. In figure 1, the device 6 is represented as a conveyor belt, but it is evident that the device 6 receiving the components 2 in succession in the output station S2 can be any type of device of a manufacturing machine to manufacture hygiene absorbent articles.

The conveyor 5 comprises a closed curved guide 7 (i.e. closed in a ring shape forming a circuit without a start or an end), which is arranged in a fixed position along the application path P. Furthermore, the conveyor 5 comprises a plurality of equipments 8, each supporting a respective holding head 4 and provided with three slides 9, each coupled to the guide 7 so as to freely slide along the guide 7 by means of a plurality of wheels 10, which are idle on the slide 9 and roll along respective rolling surfaces 11 of the guide 7 (as shown in figure 2). According to other embodiments which are not shown herein, each equipment 8 comprises a different number of slides 9 (for example one single slide 9, two slides 9, four slides 9...).

Finally, according to figure 3, the conveyor 5 comprises a linear electric motor 12, which moves the slides 9 carrying the equipments 8 and, hence, the sucking holding heads 4 along the application path P. The linear electric motor 12 comprises a closed curved stator 13 (i.e. a fixed primary element), which is arranged in a fixed position along the guide 7, and a plurality of movable sliders 14 (i.e. movable secondary elements), each electro- magnetically coupled to the stator 13 so as to receive, from the stator 13, a driving force and rigidly connected to a corresponding slide 9.

The stator 13 of the linear electric motor 12 comprises a ferromagnetic armature having a series of slots housing windings designed to be run through electric currents variable in time in order to generate corresponding stator magnetic fields (which are variable in time). According to figure 6, each slider 14 of the linear electric motor 12 comprises a ferromagnetic armature in which there is arranged at least one permanent magnet 15 generating a rotor magnetic field (which is constant in time) interacting with the stator magnetic field (which is variable in time) in order to generate, on the slider 14, a driving force of electromagnetic origin. In each slide 9, the slider 14 is mounted so as to be very close to the stator 13 (approximately 1-2 millimetres away), so as to minimize the gap existing between the ferromagnetic armature of the slider 14 and the ferromagnetic armature of the stator 13.

A control device is provided, which controls the linear electric motor 12 applying a variable voltage to the windings of the stator 13. The control device preferably uses a closed loop (i.e. feedback) control system to control the position of each slider 14 (hence, of each slide 9). As a consequence, the control device must know, in real time and with a good precision, the actual position of each slider 14 (hence, of each slide 9) along the application path P; to this aim, the control device can track the actual position of each slider 14 along the application path P by means of estimation algorithms based on electrical signals at the ends of the windings of the stator 13 or the control device can receive the detection of a dedicated sensor, which is arranged along the application path P. For example, the position sensor comprises a magnetoresistive material measuring band, which is arranged along the application path P, and, for each slider 12, a corresponding permanent magnet 15, which is arranged close to the measuring band. In other words, along the application path P there is an encoder detection device, which allows the position of each permanent magnet 15 associated with each slider 14 to be detected with precision.

According to figure 3, the stator 13 of the linear electric motor 12 is parallel to the guide 7 and adjacent to the guide 7. In other words, the stator 13 of the linear electric motor 12 and the guide 7 are arranged on two parallel planes; in this way, the stator 13 of the linear electric motor 12 can be mechanically connected close to the guide 7.

According to a preferred, though non-binding embodiment, the stator 13 of the linear electric motor 12 is divided into different sectors (twelve in figure 3, but there could be more or less of them) arranged one after the other along the guide 7. The single sectors of the stator 13 are mechanically and electrically independent of one another, namely each sector of the stator 13 is electrically powered by a control device of its own, which is exclusively dedicated to its sector (hence, is different and separate from the control devices of the other sectors); obviously, there is a central control unit, which controls the control devices in a coordinated manner so as to move the slides 9 (hence, the corresponding sucking holding heads 4) along the application path P according to a desired law of motion.

According to figure 7, the guide 7 has, on the rolling surfaces 11, a transverse profile 16 having a concavity or a convexity. The wheels 10 have, on the surface in contact with the guide 7, a transverse profile 17, which has a convexity or a concavity, which is complementary to the profile 16 (namely, when the profile 16 is convex, the corresponding profile 17 is concave and vice versa). The profile 17 generates, with the profile 16, a shape coupling between the guide 7 and the wheels 10, which prevents the slide 9 from moving crosswise relative to the guide 7. In other words, the shape coupling generated between the transverse profile 16 of the guide 7 and the transverse profile 17 of each wheel 10 prevents the slide 9 from moving along a direction T which is transverse to the guide 7, so as to also prevent the slide 9 from derailing out of the guide 7.

Advantageously, though not necessarily, the profile 16 and the profile 17 are“V”-shaped. In this way, thanks to the presence of the vertex in the“V” shape, a high precision of the application path P followed by the wheels is ensured.

According to a preferred, though non-limiting embodiment shown in figures 1, 2, 7, 9 and 10, each slide 9 has at least one pair of opposite wheels 10, which are coupled to a side 18 and to a side 19, respectively, of the guide 7 (which are opposite one another), thus forbidding the movement of the slide 9 relative to the guide 7 along a direction R (shown in figure 7), which is radial to the application path P. In the preferred, though non-limiting embodiment shown in figures 1, 2, 7, 9 and 10, each slide 9 has three wheels 10: two smaller wheels 10, which slide along the side 19 of the guide 7, and a larger wheel 10, which slides along the side 18 of the guide 7.

According to a preferred, though non-limiting embodiment shown in figure 2, the guide 7 comprises two tracks 20, which are parallel to one another and spaced apart from one another. As a consequence, the equipment 8 comprises two groups of opposite slides 9 (each group for each track 20) and a connection element 21, which connects the two groups of slides 9 to one another and supports the holding head 4.

According to figures 4 and 8, advantageously, in each slide 9 the wheels 10 of one of the slides 9 are floating relative to the corresponding slide 9 along a compensation direction C, which is transverse to the application path P. By so doing, building and/or assembling imperfections, which unavoidably arise in the parallel arrangement and in the uniform character of the two tracks 20, can be solved.

According to a preferred, though non-limiting embodiment shown, for example, in figures 8, 9 and 10, each slide 9 is provided with three wheels 10. In particular two (smaller) wheels 10 slide on the outer rolling surface 11 of the guide 7, namely along the side 19 of the guide 7, whereas one single (larger) wheel 10 slides on the inner rolling surface 11 of the guide 7, namely along the side 18 of the guide 7. In this way, the (larger) wheel 10 sliding along the side 18 of the guide 7 forms, with the two (smaller) wheels 10 sliding along the side 19 of the guide 7, two pairs of wheels 10, one with each one of the (smaller) wheels 10 sliding along the side 19 of the guide 7.

Advantageously, though not necessarily, each equipment 8 comprises two trains 22 of slides 9, each comprising three slides 9 which slide one the same track 20 (alternatively, each train 22 of slides 9 could comprise only one/two slides 9 or four/five slides 9). Furthermore, the connection element 21 connects at least one slide 9 sliding on a track 20 and another slide 9 sliding on the other track 20 to one another.

Two slides 9 sliding on the same track 20 are connected in an articulated manner by means of a fork (figure 5) or by means of a connecting rod 23 (having a fork at one of the ends and shown in figure 10), which permit a relative rotation of the two slides 9 sliding on the same track 20 along the curved segments of the guide 7.

According to a preferred embodiment, each equipment 8 comprises two trains 22 of slides 9, each comprising three slides 9, which slide on a same track 20. Furthermore, the connection element 21 connects the sole central slide 9 of a train 22 to the sole central slide 9 of the other train. According to a further preferred embodiment of the invention, the floating wheels 10 are present only on the slide 9 arranged at the centre (namely, arranged between the two side slides 9). This is due to the fact that, as far as the side slides 9 (arranged on opposite sides of the central slide 9) are concerned, the function of compensation of the parallel arrangement and of possible lacks of homogeneity between the different tracks 20 is fulfilled (enabled) by the connecting rod 23 connecting the two side slides 9 to the central slide 9.

According to a preferred, though non-limiting embodiment shown in figure 1, the feeding unit 1 comprises a rotation station S3, which is arranged along the feeding path P and where each holding head 4 makes a rotation relative to the equipment 8 and around a rotation axis Rl (shown in figures 4 and 8) in order to change the orientation of the component 2. In particular, each sucking holding head 4 is mounted in a rotary manner on the equipment 8 so as to rotate around the rotation axis Rl and there is a cam operating system 25 to control the rotation of the sucking holding head 4 around the rotation axis Rl.

According to figures 3, 4 and 8, the cam operating system 25 comprises a cam 26 (shown in figure 3), which is arranged in a fixed position beside the guide 7 and along the application path P, and, for each holding head 4, at least one corresponding cam follower roller 27 (shown in figures 4 and 8), which is coupled to the cam 26 (namely, slides on the cam 26 so as to follow the profile of the cam 26) and is mechanically connected to the sucking holding head 4.

According to a preferred non-limiting embodiment (shown in figures 4 and 8), in each equipment 8 the cam follower roller 27 is oriented parallel to the rotation axis Rl; further optimizations are possible by causing the axis Rl and the symmetry axis of the cam follower roller 27 to converge in a suitable point; furthermore, there is an operating arm 28 having a first end, on which there is mounted, in a rotary manner, the roller 27, and a second end, which is angularly integral to the sucking holding head 4. In this embodiment, an end of each operating arm 28 is directly constrained to a shaft supporting the sucking holding head 4, so that the rotary movement of the operating arm 28 becomes a same rotary movement of the sucking holding head 4.

According to a further embodiment shown in figure 3, the cam 26 is interrupted along a portion of the application path P, so as to permit the introduction of stations, interfering in terms of space, along the application path P (such as, for example, a cutting station). In this embodiment, a locking device 29 (shown in figures 4 and 8) is provided, which prevents the holding head 4 from rotating around the rotation axis Rl, so as to avoid accidental rotations of the holding head 4 along the segment where the cam 26 is interrupted.

Furthermore, a control device is provided, which activates the locking device 29 upstream of the portion of the application path P where the cam 26 is interrupted and deactivates the locking device 29 downstream of the portion of the application path P where the cam 26 is interrupted. In other words, the locking device 29 shifts from an active (locking) position, in which the locking device 29 prevents the holding head 4 from rotating around the rotation axis Rl, to a passive (release) position, in which the locking device 29 allows the holding head 4 to freely rotate controlled by the cam 26 by means of the cam follower roller 27.

According to a possible embodiment, the locking device 29 comprises a locking pin 30, which can axially slide between an active position and a passive position. Furthermore, the control device comprises an elastic element, which pushes the locking pin 30 towards the active position, and an actuator element (not shown), which pushes the locking pin 30 towards the passive position, thus compressing the elastic element. According to a preferred, though non-limiting embodiment of the invention, the locking pin 30 is made of a ferromagnetic material and the actuator element consists of a magnet (not shown), which magnetically attracts the locking pin 30 towards the passive position.

According to a further embodiment, the feeding unit 1 comprises a rotation station S4, which is arranged along the feeding path P (figure 1) and in which the holding head 4 makes a rotation relative to the equipment 8 and around a rotation axis R2 (shown in figures 4 and 6), which is transverse to the feeding path P, so as to change the inclination of the holding head 4. In this way, the angle a (shown in figure 1) existing between each holding head 4 and the guide 7 can be changed in order to allow the holding head 4 to approach the continuous band 3 in an ideal manner.

In particular, the rotation around the rotation axis R2 takes place by means of a further cam operating system 31, which is completely similar to the operating system 25. As a consequence, the further operating system 31 also comprises a cam follower roller 24 (shown, for example, in figures 4 and 6) and a cam (nor shown), on which the cam follower roller 24 slides.

According to a preferred non-limiting embodiment, as already mentioned above and according to figure 1, in the input station S l the holding head 4 receives a corresponding component 2 connected, without gaps, to a continuous band 3; furthermore, there is a cutting station S5, which is arranged along the application path P downstream of the input station S l and is provided with a cutting device 32, which cuts the continuous band 3 crosswise so as to separate the component 2 held by the holding head 4 from the remaining part of the continuous band 3. In other words, when, in the input station S l, a component 2 is engaged by a corresponding sucking holding head 4, the component 2 is still part of the continuous band 3 (namely, is connected without gaps to the continuous band 3) and is separated from the continuous band 3 by means of crosswise cut in the cutting station S5 arranged downstream of the input station S l.

According to a further non-limiting embodiment, upstream of the input station S 1 (hence, since the guide 7 is closed, between the output station S2 and the input station S l) there is the second rotation station S4, which allows the holding head 4 to rotate around the rotation axis R2 in order to change the angle a and, hence, help the holding head approach the band 3, preventing a (sharp) end of the holding head 4 from touching the band 3, damaging it, before the holding head 4 is parallel to the band 3.

According to a preferred, though non-binding embodiment, between the cutting station S5 and the output station S2 (namely, downstream of the cutting station S5 and upstream of the output station S) there is the rotation station S3, where each sucking holding head 4 rotates by 90° (or, alternatively, by any other angle other than 90°) relative tot he conveyor 5 and around the rotation axis Rl (shown in figure 4), which is arranged radially (namely, perpendicularly) to the application path P. In particular, the cutting device 32 comprises: at least one blade 33 and at least one counter-blade 34, which cooperate with one another to cut the continuous band 3 crosswise; a cutting drum 35, which is arranged on a side of the application path P, supports the blade 33 and rotates around a rotation axis R3 so as to cyclically allow the blade 33 to come into contact with the continuous band 3; and a counter-drum 36, which is arranged on a side of the application path P opposite the cutting drum 35, supports the counter-blade 34 and rotates around a rotation axis R4 (parallel to the rotation axis R3) so as to cyclically allow the counter-blade 34 to come into contact with the continuous band 3 on the opposite side of the blade 33.

The number of blades 33 supported by the cutting drum 35 is completely independent of and variable relative to the number of counter-blades 34 supported by the counter-drum 36, since the control units of the aforesaid drums 35 and 36 are free to control them with different speeds, provided that the rhythm of contact with the band 3 is synchronous. According to a preferred, though non-limiting embodiment shown in figure 11, the unit 1 comprises a drum, which is mounted so as to rotate around a rotation axis R5 and inside which there is defined a suction chamber 37 (with a preferably cylindrical shape), which is connected in a pneumatic manner to the holding heads 4 present on the single equipments 8 by means of a flexible connection system in order to transmit a suction, namely a negative pressure relative to the room pressure, and, hence, allows the holding heads 4 to attract and hold the components 2 through suction.

The flexible connection system comprises, for each equipment 8 (namely, for each holding head 4), a corresponding flexible (articulated) hose 38, in particular made of plastic, which connects the equipment 8 (carrying a corresponding holding head 4) to the suction chamber 37 in a pneumatic manner. In order to prevent the flexible hoses 38 from intertwining and breaking due to the cyclical movement of the equipments 8, the suction chamber 37 can rotate (together with the corresponding drum) around the rotation axis R5 (corresponding to the symmetry axis of the cylindrical suction chamber 37). In other words, the suction chamber 37 rotates around the rotation axis R5 in a manner which, on average, is synchronous with the sliding of the equipments 8 along the guide 7, so as to prevent the flexible hoses 38 from intertwining and breaking In other words, the suction chamber 37 rotates around the rotation axis R5 with a rotation speed which is equal to the mean speed of the equipments 8 along a complete lap of the guide 7. Obviously, the suction chamber 37 cannot follow the movement of each equipment 8 point by point (namely, instant by instant) and, therefore, there are moments in which the suction chamber 37 is in advance or in delay relative to each equipment 8; these cyclical variations (“ pulsations”) of the distance between the suction chamber 37 and each equipment 8 are compensated by elastic deformations of the corresponding flexible hoses 38.

According to an embodiment, the rotation axis R5 is arranged in the area of the centre of gravity of the guide 7 so as to minimize the extent of the cyclical variations (“pulsations”) of the distance between the suction chamber 37 and each equipment 8. In particular, it is evident that the variation of the distance between the suction chamber 37 and the single equipment 8 is due both to a geometric factor deriving from the relationship between the shapes of the guide 7 and the suction chamber 37, respectively, and to the law of motion with which the equipments move along the guide.

According to a possible non-limiting embodiment, the suction chamber 37 rotates at a rotation speed that is variable in time and is equal, instant by instant, to the mean of the instantaneous speeds of the equipments 8 running along the guide 7. According to an alternative non-limiting embodiment, the suction chamber 37 rotates at a rotation speed that is constant in time and is equal to the mean speed of the equipments 8 along a complete lap of the guide 7.

The embodiments described herein can be combined with one another, without for this reason going beyond the scope of protection of the invention.

In the preferred embodiment show in the accompanying figures, the feeding unit 1 described above is used in an automatic manufacturing machine to manufacture hygiene absorbent articles. According to other embodiments which are not shown herein, the feeding unit 1 described above can be used in other types of automatic manufacturing machines manufacturing products that are (even completely) different from hygiene absorbent articles; for example, the feeding unit 1 described above could be used in an automatic manufacturing machine for the production of food or in an automatic manufacturing machine to process products of the tobacco industry (for example, in a unit for forming groups of cigarettes).

The feeding unit 1 described above has numerous advantages.

First of all, the feeding unit 1 described above can stand fast production rates, as the structure of the slides 9, which is completely symmetrical relative to a plane that is parallel to and equally spaced apart from the tracks 20 of the guide 7, determines a reduced and uniform wear of the wheels 10.

Furthermore, the feeding unit 1 described above allows the components 2 to be moved with very high speeds and accelerations (hence, with fast production rates) thanks to the fact that each movable equipment 8 can be provided with a plurality of sliders 14, which, as a whole, are capable of generating a significant driving force.