TECHICAL FIELD

The present invention relates to a maker machine to manufacture hygiene absorbent articles.

PRIOR ART

As known, hygiene absorbent articles comprise an impermeable layer (e.g. polyethylene), a non-woven fabric layer permeable to liquids, and an absorbent padding enclosed therebetween. Said components are the basic elements of an absorbent article. In addition to the basic components mentioned above, the absorbent articles further comprise accessory components (such as elastic bands, fecal barriers and lateral wings) which make the structure, as well as the manufacturing, more or less complex.

A known type maker machine for manufacturing hygiene absorbent articles (for example as described in patent application W02008155618A1 ) comprises a feeding line of a continuous strip of impermeable material along which a plurality of operating units are arranged which feed the basic and accessory components intended to define the absorbent article, to the continuous strip.

Each operating unit comprises a processing device which receives in succession the respective components and processes the components themselves (e.g. a cut of the components) and an application device which receives the finished components from the processing device and applies the components to the continuous strip of impermeable material. Generally, the application device comprises a central drum which is hinged to rotate around a central rotation axis and a pair of radial support arms, each of which is hinged to the central drum to rotate, with respect to the central drum, around a rotation axis parallel to the rotation axis of the central drum and supports a sucking pick-up head adapted to receive, retain, and subsequently apply a corresponding component. Generally, also the sucking pick-up head can be hinged to the support arm to rotate with respect to the support arm around a rotation axis perpendicular to the rotation axis of the central drum. In known maker machines, in the application device the rotation of the radial arms with respect to the central drum and the possible rotation of the sucking pick-up heads with respect to the radial arms is mechanically controlled by means of a cam control system.

During a format change operation, i.e. during an operation that changes the maker machine to vary the type of hygiene absorbent articles which are made, it is often necessary to modify the law of motion of the sucking pick-up heads of the application device to adapt this law of motion to a different size and/or position of the components that are to be processed. Modifying the law of motion of the pick-up heads requires the replacement of some mechanical components (typically at least the corresponding cams) and said substitution is particularly long and complex because for the disassembly of the old mechanical components and for the subsequent assembly of the new mechanical components a setup step must follow, which is quite laborious and requires the intervention of a skilled technician.

DESCRIPTION OF THE INVENTION

The object of the present invention is to provide a maker machine to manufacture hygiene absorbent articles which is free from the drawbacks described above and, at the same time, is simple and inexpensive to manufacture.

According to the present invention, a maker machine to manufacture hygiene absorbent articles, as claimed in the attached claims is provided. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the accompanying drawings, which illustrate some examples of non-limiting embodiments, wherein:

· Figure 1 is a schematic front view of a maker machine to manufacture hygiene absorbent articles manufactured according to the present invention;

• Figure 2 is a perspective and schematic view of part of a feeding line of the maker machine of Figure 1;

· Figure 3 is a schematic front view of an operating unit of the maker machine of Figure 1;

Figure 4 is a front view of an application device of the operating unit of Figure 3;

Figure 5 is a front perspective view of the application device of Figure 4;

Figure 6 is a rear perspective view of the application device of Figure 4;

• Figure 7 is a rear perspective view and with the removal of parts for clarity of the application device of Figure 4;

· Figure 8 is a front perspective view of a fixed guide and of a stator of a linear electric motor of the application device of Figure 4;

Figure 9 is a side view of a mobile assembly of the application device of Figure 4;

· Figures 10 and 11 are two different perspective views of the mobile assembly of Figure 9;

• Figure 12 is a front perspective view of an alternative of the application device of Figure 4;

Figure 13 is a rear perspective view of the application device of Figure 12;

• Figure 14 is a rear perspective view and with the removal of parts for clarity of the application device of Figure 12;

• Figure 15 is a perspective view of a mobile assembly of the application device of Figure 12;

· Figure 16 is a front perspective view of a different embodiment of the application device of Figure 4; Figure 17 is a rear perspective view of the application device of Figure 16;

Figure 18 is a front perspective view of a different embodiment of the application device of Figure 12; and

· Figure 19 is a rear perspective view of the application device of Figure 18.

PREFERRED EMBODIMENTS OF THE INVENTION

In Figure 1, number 1 denotes as a whole a maker machine to manufacture hygiene absorbent articles 2 (for example diapers) .

As illustrated in Figure 2, each hygiene absorbent article 2 comprises a sheet 3 of impermeable material (e.g. polyethylene) and a sheet 4 of permeable material (for example, "non-woven fabric") between which an absorbent padding 5 is enclosed which forms the part of the hygiene absorbent article 2 used for absorbing organic liquids. The absorbent padding 5 is normally (but not necessarily) formed by a homogeneous mixture of natural fibrous material ("fluff") and superabsorbent polymer material ("SAP") . Furthermore, in order to increase the absorbent capacity, the padding 5 could also comprise a discrete layer of superabsorbent polymer material ("SAP") defining a further absorbent material; preferably, said superabsorbent polymer material is a granular superabsorbent polymer material. Each hygiene absorbent article 2 also comprises two pairs of lateral wings 6 which extend transversely from opposite sides of the hygiene absorbent article 2 and are adapted, in use, to overlap each other for closing the hygiene absorbent article 2 around the waist of the user.

As illustrated in Figure 1, the maker machine 1 comprises a feeding line 7, which feeds, along a straight and horizontal forming path PI at least one continuous strip of impermeable material, which is intended to define a succession of sheets 3 of impermeable material. Furthermore, the maker machine 1 comprises a plurality of operating units 8, which are arranged along the feeding line 7 (i.e. along the forming path PI) and feed the corresponding components of the hygiene absorbent articles 2 (i.e. the sheets 4 of permeable material, the padding 5 and the wings 6) to the sheets 3 of impermeable material .

Along the feeding line 7 (i.e. along the forming path PI), the first operating unit 8a is a forming and application unit 8 for a succession of absorbent padding 5. Downstream from the operating unit 8a additional operating units 8b and 8c are arranged which manufacture the accessories of the hygiene absorbent articles 2 (for example elastic bands, fecal barriers and lateral wings 6), and apply the accessories to the sheets 3 of impermeable material. Finally, at the end of the feeding line 7 (i.e. at the end of the forming path PI) an operating unit 8d is arranged, which applies the sheets 4 of permeable material over the sheets 3 of impermeable material so as to enclose between each sheet 3 of impermeable material and the corresponding sheet 4 of a permeable material an absorbent padding 5. Obviously the arrangement of the operating units 8 along the feeding line 7 (i.e. along the forming path PI) can be different.

As illustrated in Figure 3, the operating unit 8c applies a succession of components (in particular the lateral wings 6) to the sheets 3 of impermeable material carried by the feeding line 7 along the forming path PI. The operating unit 8c comprises a processing device 9 which receives the components in succession and processes the components (in particular, performs the cutting of the components) and an application device 10, which receives the finished components from the processing device 9 and applies the components to the sheets 3 of impermeable material carried by the feeding line 7. The application device 10 comprises a plurality of sucking pick-up heads 11 (only two of which are illustrated in Figure 3 for clarity) each adapted to receive, hold and subsequently apply a corresponding component, and a conveyor 12 which supports the sucking pick-up heads 11 and cyclically moves each sucking pick-up head 11 along a circular application path P2 that passes through a pick-up station SI wherein the sucking pick-up head 11 receives a corresponding component from the processing device 9 and a release station S2, in which the sucking pick-up head 11 applies the component to a corresponding sheet 3 of impermeable material carried by the feeding line 7.

According to a preferred (but not binding) embodiment, each sucking pick-up head 11 is mounted to rotate upon itself around a rotation axis 13 arranged in a radial manner (i.e. perpendicular) to the application path P2. In use, between the pick-up station SI and the release station S2 each sucking pick-up head 11 carrying a component performs a 90° rotation around the corresponding rotation axis 13 so as to change the orientation of the component carried by the sucking pick-up head 11; between the release station S2 and the pick-up station SI each sucking pick-up head 11 devoid of component performs a counter-rotation (i.e. a rotation in the opposite direction) of 90° around the corresponding rotation axis 13 to return to the starting position before receiving a new component .

As illustrated in Figure 4, the conveyor 12 comprises an annular guide 14 (i.e. closed in a loop upon itself) which is arranged in a fixed position along the application path P2; in particular, the annular guide 14 is formed by a single fixed rail (i.e. without movement) that is arranged along the application path P2. Furthermore, the conveyor 12 comprises a plurality of slides 15, each of which supports a corresponding sucking pick-up head 11 and is coupled to the guide 14 so as to freely slide along the guide 14. Finally, the conveyor 12 comprises a linear electric motor 16 which moves the slides 15 carrying the sucking pick-up heads 11 along the application path P2; the linear electric motor 16 comprises an annular stator 17 (i.e. a primary fixed one) which is arranged in a fixed position along the guide 14 and a plurality of mobile sliders 18 (i.e. secondary mobile ones), each of which is electro-magnetically coupled to the stator so as to receive, from the stator 17 a driving force and is rigidly connected to a corresponding slide 15.

The stator 17 of the electric linear motor 16 comprises a ferromagnetic armature having a series of slots housing windings adapted to be crossed by electrical currents variable over time to generate corresponding stator magnetic fields (variables in time) ; each slider 18 of the linear electric motor 16 comprises a ferromagnetic armature in which at least one permanent magnet is arranged, which generates a rotor magnetic field (constant in time) that interacts with the magnetic field of the stator to generate, on the slider 18, a driving force of electromagnetic source. In each slide 15, the slider 18 is mounted so as to be in close proximity (approximately 1-2 mm) with the stator 17 to minimize the air gap existing between the ferromagnetic armature of the slider 18 and the ferromagnetic armature of the stator 17.

A control device which drives the linear electric motor 16 by applying a variable voltage to the windings of the stator 17 is provided. Preferably, the control device uses a closed loop control system (that is, in feedback) to control the position of each slider 18 (therefore of each slide 15) . Consequently, the control device must know in real time and with good precision the actual location of each slider 18 (therefore of each slide 15) along the application path P2; for this purpose, the control device can reconstruct the actual position of each slider 18 along the application path P2 by means of estimation algorithms based on electrical signals at the winding heads of the stator 17 or the control device can receive the detection of a specific position sensor which is arranged along the application path P2. For example, the position sensor comprises a measuring ring in magnetostrictive material that is arranged along the application path P2 and, for each slider 18, a corresponding permanent magnet that is arranged in proximity to the measuring ring. As previously mentioned, each sucking pick-up head 11 is mounted in a rotary manner on the corresponding slide 15 so as to rotate around a rotation axis 13; the conveyor 12 comprises a cam actuating system, so as to control the rotation of each sucking pick-up head 11 around the rotation axis 13. As illustrated in Figures 6 and 7, the cam actuating system comprises a cam 19 (not illustrated in Figure 7) arranged in a fixed position beside to the guide 14 and along the application path P2 and, for each pick-up head 11, a corresponding cam follower roller 20 which is coupled to the cam 19 (i.e. it slides on the cam 19 to follow the profile of the cam 19) and is mechanically connected to the sucking pick ^¬ up head 11.

As illustrated in Figures 9, 10 and 11, in each slide 15 the cam follower roller 20 is oriented parallel to the rotation axis 13; furthermore, an actuation arm 21 is provided, which has a first end on which the cam follower roller 20 is mounted in a rotary manner and a second end which is angularly integral with the sucking pick-up head 11. In this embodiment, one end of each actuation arm 21 is directly bound to a shaft which supports the sucking pick-up head 11 so that the rotary movement of the actuation arm 21 becomes equal to a rotary movement of the sucking pick-up head 11. According to a preferred embodiment illustrated in Figures 5 and 6, the conveyor 12 comprises a support element 22, which is arranged beside the guide 14 and in which the cam 19 is formed. In other words, the cam 19 is formed in the support element 22 which is at least initially separate and independent of the guide 14 and is arranged beside the guide 14.

As illustrated in Figures 9, 10 and 11, each slide 15 is "U"- shaped and embraces the guide 14 on both sides of the guide 14 (as illustrated in Figure 11) ; in other words, each slide 15 has two legs which are facing and opposite to one another and embrace the guide 14 between one another (i.e. between the two legs of the slide 15 a chamber is defined which accommodates the guide 14) . Each slide 15 supports a plurality of wheels 23, which are fitted on the slide 15 in an idle manner and roll along respective rolling surfaces 24 of the guide 14; in particular, each leg of the slide 15 supports two pairs of wheels 23 (in each pair of wheels 23 the two wheels 23 are arranged side by side, whereas the two pairs of wheels 23 of a same leg of the slide 15 are mutually opposite and oriented perpendicularly with respect to one another) . On each side the guide 14 comprises a pair of rolling surfaces 24 (illustrated in figures 8 and 11) , which are arranged at a given distance from one another, are oriented perpendicularly one with respect to the other, and are coupled to corresponding wheels 23 of the slide 15. The presence of the wheels 23 allows each slide 15 to slide along the guide 24 with a very low friction and at the same time ensures a transverse containment of the slide 15; i.e. each slide 15 can only slide along the guide 24 without making any movement perpendicular to the guide 24.

As illustrated in Figures 9, 10 and 11, each slide 15 is provided with a bracket 25, which projects from the slide 15 and supports the sucking pick-up head 11; in particular, the end of the bracket 25 protruding from the slide 15 has a through hole inside which a bearing is housed which carries a shaft supporting the corresponding sucking pick-up head 11. As illustrated more clearly in Figure 8, the stator 17 of the linear electric motor 16 is arranged coplanar with the guide 14 and inside the guide 14. In other words, the stator 17 of the linear electric motor 16 and the guide 14 are arranged on a same plane and one inside the other; in this way, the stator 17 of the linear electric motor 16 can be mechanically connected (typically by means of screws) to the guide 14. According to a preferred, but not binding, embodiment, the stator 17 of the linear electric motor 16 is divided into different sectors (four in figure 8, but can be more or less) arranged one following the other along the guide 14. The individual sectors of the stator 17 are mechanically and electrically independent, i.e. each sector of the stator 17 is electrically powered by its own driving device that is exclusively dedicated to its own sector (therefore is different and separate from the driving devices of the other sectors); obviously a central control unit is provided which controls in a coordinated manner the four driving devices for moving the slides 15 (therefore the corresponding sucking pick-up heads 11) along the application path P2 according to the desired law of motion.

In the embodiment illustrated in Figures 4-11, the cam follower rollers 20 are oriented parallel to the corresponding rotation axes 13 (as clearly illustrated in Figures 9, 10 and 11); in the alternative illustrated in Figures 12-15, the cam follower rollers 20 are oriented perpendicular to the corresponding rotation axes 13 (as clearly illustrated in Figure 15) . As illustrated in Figure 15, in each slide 15 the actuation arm 21 has a first end, on which the cam follower roller 20 is fitted in a rotary manner and a second end, which is mechanically connected to the sucking pick-up head 11 by means of a mechanical transmission system 26. In the preferred, but not limiting, embodiment illustrated in Figure 15, the mechanical transmission system 26 comprises a gear wheel 27 angularly integral with the actuation arm 21 and a gear wheel 28 which is angularly integral with the sucking pick-up head 11 (in particular is keyed to a shaft which supports the sucking pick-up head 11), meshes with the gear wheel 27, and is oriented perpendicular to the gear wheel 27.

According to a possible embodiment, each slide 15 receives the suction from the guide 14: on an outer surface of the guide 14 a chamber is formed which communicates on the inside with a suction source and is open on the outside towards the slide 15; therefore each slide 15 imparts suction to the corresponding sucking pick-up head 11 by means of inner ducts provided with a rotary pneumatic joint at the shaft which supports the sucking pick-up head 11 or by means of a flexible outer tube which is able to follow the 90° rotation of the sucking pick-up head 11 around the rotation axis 13.

In the embodiments illustrated in Figures 1-15, the application path P2 is circular; in alternative embodiments illustrated in Figures 16-19, the application path P2 has an oval shape having two straight sections parallel and opposite one with respect to the other which are connected by two semicircular sections opposite one with respect to the other. In the embodiment illustrated in Figures 16 and 17, the cam follower rollers 20 are oriented parallel to the corresponding rotation axes 13 (similarly to the embodiment illustrated in Figures 4-11), while in the embodiment illustrated in Figures 18 and 19, the cam follower rollers 20 are oriented perpendicular to the corresponding rotation axes 13 (similarly to the embodiment illustrated in Figures 12-15) . The oval shaped application path P2 allows to lengthen the release station S2 as each sucking pick-up head 11 can remain parallel to and facing the feeding line 7 for a particularly long section of the application path P2; in this way, the application of the finished components to the sheets 3 of impermeable material carried by the feeding line 7 can take place in a more accurate and precise manner even when operating at high hourly productivity.

In use, the linear electric motor 16 is able to control the movement of each slide 15 (therefore of each sucking pick-up head 11) along the guide 14 (i.e. along the application path P2) in a completely autonomous and independent manner of the other slides 15 (therefore of the other sucking pick-up heads 11); accordingly, each slide 15 (therefore each sucking pick- up head 11) is coupled to the guide 14 so as to freely slide along the guide 14 with a law of motion completely independent of the other slides 15 (therefore of the other sucking pick-up heads 11) . The law of motion of each slide 15 (therefore of each sucking pick-up head 11) depending solely on the software control mode of the stator 17 of the linear electric motor 16; therefore, a change in the laws of motion of the slides 15 (therefore of the sucking pick-up heads 11) is done only by acting on the control software of the stator 17 of the linear electric motor 16.

In the embodiments illustrated in the attached figures, the stator 17 of the linear electric motor 16 is arranged inside the guide 14, i.e. the stator 17 of the linear electric motor 16 is arranged in contact with an inner surface of the guide 14. According to a different embodiment not illustrated, the stator 17 of the linear electric motor 16 is arranged outside the guide 14. i.e. the stator 17 of the linear electric motor 16 is arranged in contact with an outer surface of the guide 14. According to a further embodiment not illustrated, the stator 17 of the linear electric motor 16 is arranged beside the guide 14, i.e. the stator 17 of the linear electric motor 16 is arranged in contact with a lateral surface of the guide 14. In addition, in the embodiments illustrated in the accompanying figures, the stator 17 of the linear electric motor 16 is arranged coplanar with the guide 14, i.e. the lying plane of the stator 14 is parallel and coincident with the lying plane of the guide 14. According to a different embodiment not illustrated, the lying plane of the stator 14 is perpendicular to the lying plane of the guide 14. According to a further embodiment not illustrated, the lying plane of the stator 14 is parallel to the lying plane of the guide 14 but not coincident with the lying plane of the guide 14. In the embodiments illustrated in the attached figures, the stator 17 of the linear electric motor 16 is arranged inside the guide 14 (in contact with an inner surface of the guide 14) and the stator 17 of the linear electric motor 16 is arranged coplanar with the guide 14 (i.e. the lying plane of the stator 14 is parallel and coincident with the lying plane of the guide 14) . According to a different embodiment not illustrated, the stator 17 of the linear electric motor 16 is arranged outside the guide 14 (in contact with an outer surface of the guide 14) and the lying plane of the stator 14 is perpendicular to the plane of the guide 14. According to a further embodiment not illustrated, the stator 17 of the linear electric motor 16 is arranged beside the guide 14 (in contact with a lateral surface of the guide 14) and the lying plane of the stator 14 is parallel to the lying plane of the guide 14 but not coincident with the lying plane of the guide 14. In the embodiment described above, the components that are applied to the application device 10 provided with the conveyor 12, with the linear electric motor 16, are the wings 6; it is evident that the application device 10 of the conveyor 12 provided with the linear electric motor 16 can also be used to apply any other type of component.

The maker machine 1 described above has numerous advantages.

First, in the application device 10 a format change operation, i.e. an operation that changes the maker machine 1 in order to vary the type of hygiene absorbent articles 2 that are made, is extremely simple and fast, as the only physical change that can be required is the replacement of the sucking pick-up heads 11, whereas the law of motion of the sucking pick-up heads 11 (i.e. of the slides 15) is modified thanks to an intervention on the control software. In other words, changing the law of motion of the sucking pick-up heads 11 does not require the replacement of any mechanical components, but takes place completely by way of software. Furthermore, the conveyor 9 of the application device 10 is easy and inexpensive to produce as from the mechanical point of view is relatively simple and consists of a limited number of components.