This application claims priority to Italian Patent Application 102018000008752 filed Sep. 20, 2018, the entirety of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

This invention relates to a unit and a method for forming an absorbent article and, in particular, relates to a unit and a method for forming the multilayer absorbent cores or the main bodies of sanitary articles such as, for example, baby diapers, sanitary napkins or the like.

In this description, for simplicity, express reference is made to a diaper but without thereby limiting the scope of the invention.

As is known, diapers comprise an absorbent pad or padding which is normally enclosed between a permeable inner layer of non-woven fabric and an impermeable outer layer of polyethylene.

Market requirements have led diaper manufacturers to make nappies having an absorbent pad consisting of a double absorbent layer: a first, top layer or core, which is bigger and, in use, directed towards the wearer, and underneath, a second, smaller layer or core.

The relative position of the bigger absorbent core, on top of the smaller one and offset forward to a variable extent, is determined on the basis of the wearer's sex, age or special needs.

Document US20130240125 describes a pad similar to the one mentioned above and a method for making the pad.

According to what is described in that document, the smaller absorbent core, provided with a wrapping, is first placed on a polyethylene web, normally also called “backsheet”, and the bigger core is then placed on top of the smaller one and the composite web thus formed is made to advance towards further processing stations.

One disadvantage of making these products that way, apart from the fact that the absorbent cores are placed in a wrapping, lies in the difficulty of positioning the bigger core on the smaller one and in keeping them in the right position as they advance on the carrier layer.

Moreover, since the small core is generally much thicker than the big core, it is very difficult to hold the big core against the small one and against the layer underneath that and to prevent loss of absorbent material from the cores, especially the big ones.

SUMMARY OF THE INVENTION

In this context, the main technical purpose of this invention is to propose a method and a unit for forming absorbent articles such as will be unaffected by the disadvantages mentioned above.

One aim of this disclosure is to propose a method and a unit for forming an absorbent article such as will allow precisely positioning the distinct absorbent cores making up the absorbent pad.

Another aim of this disclosure is to propose a method and a unit for forming absorbent articles such as will allow the absorbent material to be effectively retained during the forming process.

The technical purpose and aims specified are achieved by a unit for forming absorbent articles and by a method for forming absorbent articles as disclosed herein.

According to one aspect of it, this disclosure regards a method for forming an absorbent article of the type comprising a first, small absorbent core and a second, big absorbent core, placed on top of each other.

According to one aspect of it, this disclosure regards a method for forming an absorbent article comprising a step of feeding a first supporting web along a first feed path in a first feed direction and a step of placing a succession of first absorbent cores on the first supporting web at a preset spacing P.

The method comprises a step of feeding a second supporting web along a second feed path in a second feed direction and a step of placing a succession of second absorbent cores on the second supporting web at the spacing P.

According to one aspect of it, the disclosure regards a method for forming an absorbent article comprising a step of coupling the first supporting web to the second supporting web in such a way that each first absorbent core is coupled to a corresponding second absorbent core in a composite web comprising the succession of first absorbent cores and the succession of the second absorbent cores interposed between the first supporting web and the second supporting web.

Advantageously, the absorbent cores are first attached to or positioned on a respective supporting web and then the distinct webs provided with the respective absorbent cores are joined to each other to form a composite web.

According to one aspect of it, the disclosure regards a forming method comprising a step of compressing the first absorbent cores before the step of placing the succession of first absorbent cores on the first supporting web.

According to one aspect of it, the disclosure regards a forming method comprising a step of accelerating each first absorbent core before the step of placing the succession of first absorbent cores on the first supporting web, so as to space the first absorbent cores by the spacing P.

That way, thanks to an acceleration, which may be positive or negative, it is possible to space the absorbent cores by the required spacing as a function, for example, of the required size or form of the absorbent article to be made.

Preferably, the step of compressing the first absorbent cores is carried out before the step of accelerating each first absorbent core.

According to one aspect of it, the disclosure regards a forming method comprising a step of accelerating each second absorbent core before the step of placing the succession of second absorbent cores on the second supporting web, so as to space the second absorbent cores by the spacing P.

That way, thanks to an acceleration, which may be positive or negative, it is possible to space the second absorbent cores by the required spacing as a function, for example, of the required size or form of the absorbent article to be made.

Preferably, the step of compressing the second absorbent cores is carried out before the step of accelerating each second absorbent core.

According to one aspect of it, the disclosure regards a forming method wherein the step of placing the succession of second absorbent cores on the second supporting web at the spacing P is carried out while the second web moves along a curved line, specifically a circular arc.

That way, the absorbent core material not retained on the web does not drop onto the web and thus does not dirty it.

Preferably, the step of placing the succession of second absorbent cores on the second supporting web at the spacing P is carried out just before the step of coupling the first supporting web to the second supporting web.

According to one aspect of it, the disclosure regards a forming method wherein the first absorbent cores are smaller than the second absorbent cores, so that a big core is placed on a small core once the respective supporting webs have been coupled to each other.

According to one aspect of it, the disclosure regards a forming method wherein the first supporting web is the backsheet of an absorbent article and the second supporting web is the topsheet of the absorbent article.

Advantageously, according to one aspect of it, the disclosure regards a forming method wherein a small core is positioned on or attached to the backsheet of the absorbent article, a big core is coupled to the topsheet, and the backsheet and topsheet, with respective layers of the absorbent core, are joined to each other in such a way that each big core is positioned on a respective small core.

According to one aspect of it, this disclosure regards a unit for forming an absorbent article comprising a first system for feeding a first supporting web along a first feed path in a first feed direction; a first unit for forming and positioning the first absorbent core, disposed along the first feed path and comprising a first placing station for placing the first absorbent core on the first supporting web and comprising a first system for positioning the first core on the first supporting web at a spacing P, a second system for feeding a second supporting web along a second feed path in a second feed direction;

a second unit for forming and positioning the second absorbent core, disposed along the second feed path and comprising a second placing station for placing the second absorbent core on the second supporting web and comprising a second system for positioning the second absorbent core on the second supporting web at the preset spacing P; a coupling station for coupling the first supporting web to the second supporting web, disposed downstream of the first placing station and of the second placing station.

According to one aspect of the disclosure, the first and second absorbent cores overlap at least partly in the coupling station in such a way that each first absorbent core is coupled to a corresponding second absorbent core in a composite web comprising the succession of first absorbent cores and the succession of the second absorbent cores interposed between the first supporting web and the second supporting web.

According to one aspect of the disclosure, the forming unit comprises at least one compression system for compressing the absorbent cores and disposed upstream of the first placing station in a feed direction of the first absorbent cores.

According to one aspect of the disclosure, the first forming and positioning unit comprises a first accelerator for accelerating the first absorbent cores to space two consecutive first absorbent cores of the first absorbent cores by the spacing P.

According to one aspect of the disclosure, the second forming and positioning unit comprises at least a second compression system for compressing the second absorbent cores and disposed upstream of the second placing station in a feed direction of the second absorbent cores.

Preferably, the second forming and positioning unit comprises a second accelerator for accelerating the second absorbent cores to space two consecutive second absorbent cores of the second absorbent cores by the spacing P.

According to one aspect of the disclosure, the second feed system comprises a suction drum around which the second supporting web is at least partly wound and the second positioning system comprises at least one rotary carrier unit movable along a curved line, specifically a circular arc, substantially tangent to the suction drum in the placing station, the second positioning system releasing the second absorbent core onto the second supporting web along the curved line.

