CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Italian Patent Application No. 102018000020530 filed Dec. 27, 2018. The disclosure of the above application is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Embodiments of the present invention relate to a perforating apparatus of a web usable in a machine for producing sanitary absorbent articles, such as diapers, diaper-pants, incontinence pads, sanitary pads, or other articles intended to absorb bodily fluids.

In particular, embodiments of the present invention relate to a perforating apparatus of a web capable of making a plurality of holes in a web intended for making sanitary absorbent articles.

The present invention also relates to a process for perforating a web capable of making in a precise and controlled way a plurality of holes in a web, as well as a machine for producing sanitary absorbent articles comprising one or more perforating apparatuses.

BACKGROUND ART

In the production of sanitary absorbent articles, it is known to use webs having one or more zones in which holes have been made which give the sanitary absorbent article particular properties. For example, perforated webs can give breathability, diversified elasticity, or other properties in relation to the desired requirements.

To obtain sanitary absorbent articles, it is known that the webs are purchased already perforated.

That known solution involves high costs, requires lengthy times for loading in machine and for supplying, and necessitates large warehouse spaces and numbers of personnel.

The use of already perforated webs has the further disadvantage that to obtain different portions of an article having different properties it is necessary to use a plurality of webs having different configurations of holes.

That involves limits in terms of production flexibility and notably limits the types of articles which can be made. For example, that is reflected in the impossibility of making articles or batches of articles with different types of holes.

Due to the intrinsic deterioration of the webs over time, the properties of the latter may change up to the point that they are no longer suitable for the production of sanitary absorbent articles. That involves considerable economic losses, aggravated by the burden of having to dispose of the webs which are no longer usable.

Other known solutions provide for the use of perforating apparatuses installed in line which, as well as being bulky, require the web to be stopped, or notably slowed.

That involves a notable overall slowing in the production of the sanitary absorbent articles no longer acceptable due to the technical and commercial requirements of the sector.

Some known solutions use rotating rollers provided with suitable joined together protrusions and between which the web is made to advance. For example, known solutions of this type are described in document US-A-2012/276239 (US'239).

As the web advances, the joined together protrusions of the two rollers engage the web and jointly make a plurality of holes in the web.

Despite the profuse efforts by experts in the sector, such known solutions do not allow the obtainment of holes that are precise and without imperfections.

Due to the rotation of the rollers, the engagement and disengagement of the web by means of the joined together protrusions occur along a curved path substantially tangent to the advancement direction of the web which typically involves a localized variation in the advancing velocity of the web which produces stretching.

In particular, in the case in which the peripheral velocities of the rollers are equal to the advancing velocity of the web, due to the engagement and disengagement of the joined together protrusions with the web along a curved path substantially tangent to the advancement direction, it is known that many of the resulting holes have an elliptical shape.

Document US'239 also mentions the possibility of using plates with perforating elements without specifying the methods of use, or how they are configured to move in relation to the web.

Such known solutions do not allow the precise and controlled making of holes in specific zones of the web, which often prove to be non-uniform, incomplete and with multiple imperfections.

For example, the holes in the web may have unwanted elliptical shapes and/or lacerated and/or stretched portions, or in the worst cases the web may even remain accidentally caught in the perforating apparatus.

Therefore, the need exists to improve and make available a perforating apparatus, a perforating process, as well as a machine for producing sanitary absorbent articles comprising that perforating apparatus of a web which overcome at least one of the disadvantages of the prior art.

One aim of the present invention is to supply a perforating apparatus capable of making holes in a web in line which are precise and without imperfections so as to obtain sanitary absorbent articles corresponding to design expectations with high production rates.

It is an aim of the present invention to supply a perforating apparatus capable of making holes without obstructing the advancement of the web, that is to say, without locally varying the velocity of the web and consequently preventing the holes from having an elliptical shape.

It is also an aim of the present invention to supply a perforating process which allows the obtainment of holes in a web rapidly and as the web advances along an advancement path.

It is a further aim of the present invention to supply a perforating apparatus with compact dimensions and which allows holes to be made in a web as it advances and which simultaneously guarantees the reduced likelihood of it being able to accidentally become caught in the apparatus itself.

A further aim of the present invention is to supply a machine for producing sanitary absorbent articles comprising at least one perforating apparatus which allows deformations to be made in one or more desired zones of the web in a precise and controlled way.

To overcome the disadvantages of the prior art and to obtain these and further aims and advantages, the Applicant has devised, tested and made the present invention.

DISCLOSURE OF THE INVENTION

The present invention is expressed and characterized in the independent claims, while the dependent claims explain other characteristics of the present invention or variants of the main solution idea.

In accordance with the above-mentioned aims, the present invention relates to a perforating apparatus of at least one web advancing along an advancement path at an advancing velocity.

The perforating apparatus comprises at least one first deformation member provided with a plurality of openings and at least one second deformation member provided with a plurality of protruding elements.

In accordance with one aspect of the present invention, the first deformation member and the second deformation member are configured to position themselves at least in a tracking position, wherein the first deformation member and the second deformation member are placed on opposite sides of the advancement path and facing each other.

In accordance with one aspect of the present invention, the first deformation member and the second deformation member are configured to position themselves in a coupling position, wherein the protruding elements are coupled with the openings orthogonally to the advancement path to make, in use, a plurality of holes in a zone of the web.

In the coupling position, in use, the web is clamped between the first deformation member and the second deformation member so that the protruding elements perforate the web.

According to the present invention, the first deformation member and the second deformation member, in the tracking position and in the coupling position, are configured to advance along a portion parallel to the advancement path at the advancing velocity so as to make the plurality of holes with relative velocities, at least along the advancement path, between the first deformation member and the web and between the second deformation member and the web which are substantially zero.

The present invention allows the making of holes in a web in a precise and controlled way, without the resulting holes having unwanted shapes, simultaneously guaranteeing that the web is not lacerated and proceeds at the advancing velocity of the web without slowing or jamming.

The present invention overcomes the problems relative to the known solutions which use pairs of rollers which do not allow the obtainment of precise and circular holes. Although there are known solutions which use plates with perforating elements, they are not capable of making holes with a circular shape and without instantaneously slowing the advancing of the web at least in correspondence with the engagement zone of the perforating elements with the web.

The known solutions which use plates with perforating elements engage the moving web with those elements starting from a standstill and therefore at the moment of engagement the web is locally slowed causing elongation of the holes in the web.

Thanks to the present invention, it is possible to rapidly obtain perforated zones on the webs in line and having the desired shape, without using already perforated webs.

Thanks to the present solution, not using already perforated webs, it is possible to make the desired pluralities of holes in the desired zones, avoiding having to shape already perforated webs which typically may involve considerable quantities of waste.

In accordance with possible embodiments, the first deformation member comprises a first plate wherein the openings are present.

According to possible embodiments, the second deformation member comprises a second plate wherein the protruding elements are present.

According to possible embodiments, the perforating apparatus comprises disengaging means interposed between the first deformation member and the second deformation member in the coupling position configured to disengage the web from the protruding elements so that, in use, the perforated web is freed from the protruding elements.

In accordance with possible embodiments, the disengaging means comprise at least one disengaging element provided with at least one through opening wherein in the coupling position the protruding elements are inserted.

According to possible embodiments, the disengaging element may comprise a plurality of through openings.

According to possible embodiments, the perforating apparatus comprises a heating device configured to heat the protruding elements.

In accordance with possible embodiments, the perforating apparatus comprises retaining means placed along two directions parallel to the advancement path, arranged laterally to the zone of the web wherein, in use, the holes are made.

According to possible embodiments, in use, the retaining means are configured to position themselves in contact with the web for retaining the web in contact with the first deformation member or the second deformation member.

According to possible embodiments, the perforating apparatus may comprise a plurality of first deformation members and a plurality of said second deformation members, wherein each of the first deformation members and of the second deformation members is configured to move independently of the others.

According to possible embodiments, part of the surface of the first deformation member oriented, in the tracking position, towards the second deformation member is coated with a coating.

In accordance with possible embodiments, the coating may comprise silicone material.

According to possible embodiments, the first deformation member and/or the second deformation member are configured to position themselves along a direction transverse to the advancement path so that the first deformation member and the second deformation member are at least partially overlapping each other. For example, the first deformation member and the second deformation member may be entirely overlapping each other and staggered along the direction transverse to the advancement path of the web, while the web advances along the advancement path.

According to possible embodiments, the first deformation member and/or the second deformation member are configured to position themselves along a direction transverse to the advancement path so that the first deformation member and the second deformation member are partially overlapping each other. For example, the first deformation member and the second deformation member may be partially overlapping each other, while the web advances along the advancement path.

According to possible embodiments, the present invention also relates to a process for perforating at least one web, comprising:advancing the web along an advancement path at an advancing velocity;positioning at least one first deformation member provided with a plurality of openings and at least one second deformation member provided with a plurality of protruding elements in a tracking position, wherein the first deformation member and the second deformation member are placed on opposite sides of the advancement path and facing each other facing towards two opposite surfaces of said web;advancing the first deformation member and the second deformation member along a portion parallel to the advancement path at the advancing velocity, so that the relative velocities, at least along the advancement path, between the first deformation member and the web and between the second deformation member and the web are substantially zero;positioning the first deformation member and the second deformation member in a coupling position, wherein the protruding elements are coupled with the openings orthogonally to the advancement path with the web interposed between them to make a plurality of holes in a zone of the web, while the first deformation member and the second deformation member advance at the advancing velocity along a portion parallel to the advancement path so that the relative velocities remain substantially zero.

In accordance with possible embodiments, the perforating process provides that the first deformation member and/or the second deformation member are positioned along a direction transverse to the advancement path so that the first deformation member and the second deformation member are at least partially overlapping each other to couple with the web and make the plurality of holes in a zone of the web, wherein the zone extends along the transverse direction for an extension less than the transverse extension of the web relative to the advancement path.

In accordance with possible embodiments, the perforating process provides that the first deformation member and/or the second deformation member are positioned along a direction transverse to the advancement path so that the first deformation member and the second deformation member are partially overlapping each other to couple with the web and make the plurality of holes in a zone of the web, wherein the zone extends along the transverse direction for an extension less than the transverse extension of the web relative to the advancement path.

According to possible embodiments, the perforating process provides that protruding elements are heated by means of a heating device.

According to possible embodiments, the perforating process provides that disengaging means separate the web from the protruding elements so as to free the web from the protruding elements.

According to possible embodiments, the perforating process provides that retaining means position themselves in contact with the web along two directions parallel to the advancement path, arranged laterally to the zone of the web wherein holes are made to retain the web in contact with the first deformation member or the second deformation member.

According to possible embodiments, the present invention also relates to a machine for producing sanitary absorbent articles comprising at least one perforating apparatus according to any of the possible embodiments.

