ITTO20120210A1 - METHOD AND APPARATUS FOR WELDING AND CUTTING FOR THE PRODUCTION OF SINGLE-USE HYGIENIC-SANITARY ABSORBENT ARTICLES WEARABLE IN GUISA DI MUTANDINA, OF THE PRECOURED TYPE - Google Patents

Description

DESCRIPTION

â € œMethod and apparatus for welding and cutting for the production of disposable sanitary absorbent articles wearable like a panty, of the closed type.â €

TEXT OF THE DESCRIPTION

Technical field

The present description refers to welding and cutting devices which can be used in the production of sanitary hygienic articles such as for example diaper-panty products of the pre-closed type.

The reference to this specific field of application must not, however, be interpreted in a limiting sense of the scope of the invention.

Technological background

A common technique for the production of wearable sanitary products like a panty, of the pre-fastened type, normally referred to as â € œtraining pantâ € or â € œpull upâ €, consists in making a composite tape formed by a continuous chain of product blanks aligned so as to have the transverse axis of each single absorbent article coinciding with the direction of movement of the belt itself. The continuous composite tape is folded in two around said transverse axis, so as to overlap the opposite longitudinal edges of the tape with each other. The two edges of the overlapping composite tape are connected together with welding lines, so as to define the openings of the waist and legs of each absorbent article. The continuous chain of blanks, in correspondence with the welds, is subsequently subjected to a cutting operation to divide the finished products among them.

This particular production methodology is normally identified with the term â € œCross Directionâ € (or CD), distinguishing it from the more traditional form of production, called â € œMachine Directionâ € (or MD), which forms absorbent articles while traveling with their own longitudinal axis parallel to the production direction.

An example of a process for manufacturing absorbent sanitary products of the CD type is described in documents EP-A-1 013 251 and IT-0001379452 of the same applicant.

In the CD procedures it is necessary to ensure correct positioning of the transverse welds of each product, in order to correctly define the waist and leg openings of each individual diaper. Furthermore, it is important that the cutting line used to divide the individual products between them is correctly positioned in correspondence with the welds made between two adjacent absorbent products and, very importantly, both the welds and the cuts must have a constant angular position with respect to to the direction of advancement of the sheet, that is, in other words, they must always have, at least the welds, the same angular relationship with respect to the edges of the composite tape.

According to the known art, in order to obtain sanitary articles with welds and cuts in a correct phase relationship between them and with an angular relationship with respect to the edges of the article constant over time, extremely complex and expensive equipment is required, where the aforesaid welding and cutting operations are carried out on a single roller around which the continuous strip made up of the blanks of the individual absorbent articles is wound.

It is obvious to the expert that a solution of this type brings with it problems that are difficult to solve, such as for example the complexity of the apparatus and the lack of flexibility in changing the format of the articles, with the consequent increase in management costs. The lack of flexibility in the format change is essentially due to the fact that the diameter of the roller must be chosen so that the circumference is an integer multiple of the transversal development of the absorbent product being produced, therefore changing the article changes the transversal development of the product. Absorbent and, consequently, the diameter of the roller, therefore the entire welding and cutting unit must be replaced.

The complexity of the known apparatus derives from the fact that the cutting and welding tools must be able to be housed around a single roller which acts as a contrast for both the welding and cutting operations. Therefore, said roller must have a large diameter in order to be able to house both the welding mechanisms and the cutting devices on its periphery and, due to the delicacy of both processes, said roller must have an equally high precision which increases its costs.

The above is aggravated by the fact that in order to carry out a welding with adequate mechanical characteristics it is necessary to heat the composite strip formed by the continuous chain of blanks. To this end, normally, the aforementioned heating is obtained by inserting resistances in the areas in charge of welding which, obviously, are also cutting areas. Due to the large diameter of the contrast roller and, therefore, to the resulting important mass, the management of the temperature of the aforementioned contrast areas presents problems that are difficult to solve which lead to a reduction in the life of the welding and cutting tools. inevitably they are affected by temperature variations and therefore by the consequent dimensional variations of the common contrasting element.

Purpose and summary

The purpose of the present invention is to improve the technique for the production of sanitary sanitary articles that can be worn as a panty of the closed type, so that the opposite transversal edges of each article always maintain the correct relationship of shape and phase with the corresponding transverse welding line.

According to the present invention, this object is achieved by an apparatus and a process forming the subject of claims 1, 4 and 12.

The claims form an integral part of the teaching administered in relation to the invention.

Brief description of the figures

The invention will now be described, purely by way of non-limiting example, with reference to the attached figures, in which:

- Figure 1 is a perspective view of an absorbent product of the pre-closed panty type that can be produced with the apparatus according to a preferred embodiment of the present invention, in a closed configuration ready for use,

- figure 2 is a schematic perspective view of the absorbent product of figure 1 in an extended configuration, - figure 3 is a schematic perspective view of the production steps of an absorbent article of the type shown in figures 1 and 2,

- Figures 4 and 5 are schematic perspective views of an equipment for producing absorbent articles according to a preferred embodiment of the present invention,

- figure 6 is a schematic perspective view of the detail relating to the welding equipment according to a preferred embodiment of the present invention,

Figure 7 schematically illustrates the characteristics of welding and cutting in articles made according to a preferred embodiment described here, and

Figure 8 illustrates in a side view the detail relating to the cutting device according to a preferred embodiment of the present invention.

- Figures 9a and 9b are each respectively a schematic perspective view of the detail relating to the welding equipment according to a further preferred embodiment of the present invention.

Detailed description of embodiments

The following description illustrates various specific details aimed at an in-depth understanding of the embodiments. The embodiments can be made without one or more of the specific details, or with other methods, components, materials, etc. In other cases, known structures, materials or operations are not shown or described in detail to avoid obscuring various aspects of the forms of implementation.

Reference to "an embodiment" within this description means that a particular configuration, structure or feature described in relation to the embodiment is included in at least one embodiment. Therefore, phrases such as "in one embodiment", possibly present in different places of this description, are not necessarily referred to the same embodiment. Furthermore, particular conformations, structures or characteristics can be suitably combined in one or more embodiments.

The references used here are for convenience only and therefore do not define the scope of protection or the scope of the forms of implementation, therefore the `` front '' or `` rear '' definitions referring to the sanitary napkin article depend only on the sanitary napkin article. final use of the product itself, i.e. on how it is worn by the user, while the definitions `` upper '' or `` lower '' relating to any elements present in one or more of the described embodiments depend only on the point of view of Observer with respect to the drawings attached to this document without, therefore, limiting the principle and / or scope of the invention.

With reference to Figures 1 and 2, 10 indicates a disposable absorbent product of the so-called pull-on or training pant type made with a method and an apparatus in accordance with the teachings administered by the present invention.

In figure 1 the absorbent article is represented in its closed condition, where it has a conformation substantially similar to that of a panty. While figure 2 represents the same product of figure 1 in an extended or open configuration, that is, before being folded around its transverse axis X2 and before having carried out the welds 13 that will give it the characteristic panty conformation, defining the waist opening 14 and the two leg openings 11.

In essential terms, the product 10 consists of a chassis 1, or external part of the absorbent product, which, during the use of the hygienic article, supports and keeps the absorbent insert 2 in contact with the body of the ™ user.

Diapers of this type can have different shapes and structures, therefore the shape and structure of the absorbent diaper that is described below in this document is to be understood only by way of example, in order to better appreciate the advantages of the present invention.

The absorbent product shown in figures 1 and 2 has the chassis 1 which can be made from an external sheet 4 and an internal sheet 5 between which elastic elements 16 and 17 can be interposed which contribute to increasing the wearability characteristics.

The elastic elements 16 extend along the front 5 and rear 7 waist edges and are designed to elasticise the opening for the waist 14. The elastic elements 17 are designed to elasticise the opening of the legs 11.

The two sheets 4 and 5, making up the chassis 1, are normally non-woven fabrics (or Non Woven) that may have undergone treatments that make them impermeable to liquids, in order to contain any leaks of liquids and avoid any possible contamination of the wearer's clothing with which chassis 1 is in contact.

The elastic materials 16 and 17, in turn, can be chosen from the multiplicity of materials available on the market, such as synthetic rubber strips produced by Fulflex or Lycra® threads produced by Invista.

In the absorbent product, shown in Figures 1 and 2, on the chassis 1, in the inguinal region 3, placed between the two front waist regions 9, rear 15 and the openings for the legs 11, there is the absorbent insert 2 which It is intended to come into contact with the user's body, assuming the general U-shape. The function of the absorbent insert 2 is to collect and retain body exudates.

One of the functions of the elastic elements 16 and 17 of the chassis 1 described above is to keep the absorbent insert 2 in the correct working position, even when it becomes heavy due to having absorbed the body exudates.

The two sheets 4 and 5 constituting the chassis 1 and the aforementioned elastic materials 16 and 17 are made integral by means of adhesives and / or thanks to welding carried out with heated rollers or ultrasound systems.

The absorbent insert 2 has a structure in which they are recognizable (in addition to various other accessory elements):

- an upper layer or topsheet 18 permeable to evacuated body fluids, intended to be turned towards the user's body;

- a lower layer or backsheet 19 impermeable to body fluids and intended to be facing outwards, ie towards the chassis 1; And

- an absorbent core or â € œcoreâ € 20 interposed between the topsheet 18 and the backsheet 19 designed to absorb and retain the exudates.

On the absorbent product 10, and in particular on the absorbent insert 2, other characteristic elements may be present which contribute to increasing the characteristics of wearability and absorbency, such as for example the so-called cuffs or elasticized sides 25 arranged on the sides of the absorbent core 20 with function of lateral containment of body fluids.

For a more detailed description of the elements listed above and others, well known to those skilled in the art, please refer to the extensive literature existing on the subject, such as, for example, U.S. 4,704,116 issued on November 3, 1987 to Enloe.

In a possible embodiment, as shown in Figures 1 and 2, the absorbent insert 2 and the chassis 1 are made integral with each other by means of adhesive strips 24 and / or by welding made with each system per se It is known, such as for example thermo-mechanical or ultrasonic welding.

As shown in Figure 2, moreover, a cut 6 of suitable shape is normally made on the chassis 1 which defines and delineates the contour of the openings of the legs 11.

As is evident to the skilled person, the representations of figures 1 and 2 are schematic in nature and intend to highlight that the method and the apparatus object of the present invention can be applied to a wide variety of possible types of the absorbent product 10 .

Figure 3 schematically represents part of the production process of a sanitary napkin 10. In figure 3, 100 indicates a composite belt, formed by a chain of blanks of absorbent sanitary products 10, which advances continuously in a longitudinal direction A. The composite tape 100 has two opposite longitudinal ends 31 and 32, which respectively form the front waist edge 5 and the rear waist edge 7 on the product. Said edges, during the production process of the sanitary napkin sanitary, are superimposed on each other following a folding around the bar 36 parallel to the longitudinal feed direction A of the belt 100 and coincident, normally, with the axis of symmetry X2 of the single absorbent products 10, in the longitudinal folding station 30 , of which the 36 bar is an essential component. The arrow C schematically indicates the folding movement which leads to the overlapping of the longitudinal edges 31 and 32. After the folding around the longitudinal axis X2 the front flap 33 and the rear flap 34 of the belt 100, respectively connected to the longitudinal edges 31 and 32, are joined together at regular intervals, as illustrated in the absorbent article of the pre-closed panty type of figure 1, which can be made with the apparatus according to the embodiment of the present invention exemplified here, this connection can be obtained by means of the two welds 13.

An example of equipment and process 30 suitable for making a fold of this type is described in TO2011A001085 by the same Applicant.

After the folding and closing operations, the continuous composite tape is subjected to cutting operations along the transverse lines 12 to form the individual products 10.

It will be appreciated from Figures 1 and 2 what may be the complexity of the strip that is generated in a production process in which the blanks of products 10 extend transversely to the direction of movement, it will also be appreciated that the structure of the strip and its management becomes even more complex once it is folded in two; in fact, due to the overlapping of the sheet, the differences in thickness both in the transverse and longitudinal directions of the belt 100 are considerably amplified and problems are generated in the transport of the belt 100 due to its discontinuity generated by the cuts 6 for the realization of the openings for the legs 11 present on each article 10, in fact, as is clearly illustrated in figure 3, the belt 100 has a continuous longitudinal portion (or band) 38 which coincides with the front 9 and rear 15 waist regions and a longitudinal portion (or band) discontinuous 39 which coincides with the portion that includes the inguinal region 3 placed between the two front 9 and rear 15 waist regions and the openings for the legs 11.

From what has been said, it will therefore be appreciated how difficult it is to ensure that during the welding and cutting operations of each product 10 an accurate phase relationship is always maintained between the transverse welds 13 and the cuts 12, as well as a constant angular relationship between the aforementioned transverse welds 13 and the cuts 12 with respect to the waist edges 5 and 7 of each absorbent article 10.

Figure 4 schematically illustrates the apparatus 70 according to an embodiment of the present invention.

In the embodiment exemplified here, the apparatus 70 is composed of the apparatus 40, capable of making transversal welding lines 13 suitable for defining the life line and the opening of the legs in each sanitary napkin article 10 pre-closed panty type such as the one shown in Figures 1 and 2.

In the preferred embodiment, as illustrated in Figure 5, the transverse welding station 40 can be composed of a structure 41 where a pair of counter-rotating rollers are installed, intended to perform the function of sealing roller 42 and the function of roller respectively. contrast or counter seal 43.

The strip of blanks 100 is made to pass, along the longitudinal advancement direction A, between the two sealing rollers 42 and counter-sealing rollers 43, which rotate so as to have their respective tangential speeds substantially identical to each other and equal to the linear advancement speed. of the chain of blanks 100.

The sealing rollers 42 and counter-sealing rollers 43 are operated in a known way, for example by a single motorization with the provision of transmission means, or, according to a currently preferred solution, illustrated in figures 4, 5 and 6, by means of of two independent motorizations consisting of two servomotors 44 and 45 electronically controlled between them, each mechanically connected by means of joints preferably of the homokinetic type 440 to the respective roller.

In the device described here, the welding action is achieved with the combined application of pressure and heat. To this end, both rollers carry inside them (according to a configuration known per se and used for example in packaging machines of the type called â € œflow-packâ €) heating resistors and temperature control means.

The pressure between the two rollers is guaranteed thanks to means known per se such as for example pneumatic or hydraulic or mechanical systems, well known by experts and not illustrated in the figure for simplicity of representation.

The roller 42, which is entrusted with the sealing function, is provided along its periphery with protruding welding blades 46a and 46b, transversal to the direction of advancement of the composite tape 100, in other words, substantially aligned with the axis of rotation X4 of the sealing roller itself 42, in the preferred embodiments illustrated in this document the welding blades 46a and 46b form an angle of 3 ° with any generatrix of the cylinder of the sealing roller parallel to the axis of rotation X4. € “4th.

The roller 43 which is entrusted with the contrast function, on the other hand, has a completely smooth surface.

Figure 7 of the annexed drawings represents the end regions of two sanitary articles 10 adjacent to each other and still connected in the production chain 100, with the two welding lines 13 highlighted and, interposed between them, the dashed line and point X5 which coincides with the separation line 12 between the two adjacent articles 10, which will be made with the subsequent cutting operation.

As is known, and as clearly shown in Figure 5, the welding lines 13 may present a slight convergence between them, so as to form a maximum angle of about 6 - 8 °.

In the preferred embodiment, as illustrated in Figure 4, the composite tape 100 at the exit of the folding unit is taken by a transport system 50, which, in turn, consists of:

- a first conveyor (or transport) means 51, designed to pick up the continuous part of the composite belt 100 at the output of the folder 30 and feed it to the sealing rollers 42 and 43. As is well known, the continuous part 38 of the tape 100 has a reduced thickness, being essentially constituted by the two edges 33 and 34 superimposed on each other;

- by a second conveyor (or transport) means 52, responsible for transporting the discontinuous band 39 of the belt 100 from the folder 30 to the cutting unit 60 passing through the welding unit, and

- by a third conveyor (or transport) means 53 which picks up the continuous band 38 of the belt 100 at the outlet of the sealing rollers 42 and 43 and feeds it to the cutting unit 60.

In the preferred embodiment, as better highlighted in Figure 5, the first transport 51 can be made by an upper carriage 54 and a lower carriage 55. Both carriages are equipped with suitable motor means (not shown) capable of imparting to the belt 541 of the upper carriage 54 and to the belt 551 of the lower carriage 55 a linear speed of advancement equal to that of the belt 100. The two carriages 54 and 55 are provided with mechanical means, known per se, capable of clamping the continuous edges 33 and 34 of the belt 100. Furthermore, in order to increase the clamping capacity of the chain of blanks 100 carried out by the aforementioned trolleys 54 and 55, one or both of the belts 541 and 551 can be of the â € œsuctionâ € or â € œa vacuumâ €, that is, they can have a surface permeable to air, which connected to a source of sub atmospheric pressure, with means known per se, is able to increase the overall clamping force. a applicable to the belt 100 by the transport 51.

In the preferred embodiment, also the second transport 52 can be realized by an upper trolley 56 and by a lower trolley 57. Both trolleys are equipped with suitable motor means 562, capable of giving the belts 561 and 571 two respective carriages 56 and 57, a linear speed of advancement equal to that of the belt 100 and capable in turn of keeping the discontinuous parts 39 of the belt 100 tightened together thanks to mechanical means known per se.

In order to increase the clamping capacity of the discontinuous parts of the belt 100, also in this case, one or both of the belts 561 and 571 belonging respectively to the upper carriage 56 and to the lower carriage 57 of the second transport 52, can be of the â € œsuctionâ € or â € œvacuumâ €, ie having the surface permeable to air, which connected to a sub atmospheric pressure source with means and techniques well known to skilled people in the sector, increases the overall clamping force that the conveyor 52 is able to apply to the belt 100. The conveyor system 52 grasps the discontinuous part 39 of the belt 100 at the exit of the folding system 30 and accompanies it up to the cutting group 60, passing through the welding 40 without ever leaving the discontinuous band 39 of the strip 100. The crossing of the welding station 40 by the second transport 52, as clearly evident in figures 5 and 6, is made possible by the f provided that the sealing rollers 42 and counter-sealing rollers 43 have respectively a second portion 422 of the sealing roller 42 and a second portion 432 of the counter-sealing roller 43 with the relative diameters 422â € ™ and 432â € ™ smaller than the diameters 421â € ™ and 431â Respectively of the first working portion 421 of the sealing roller 42 and of the first working portion 431 of the counter-sealing roller 43. As shown in Figure 5, the transport means 52 is able to pass through the sealing unit 40 in the space that is to create between the two second portions of sealing roller 422 and counter-sealing roller 432 with a smaller diameter than the corresponding nominal working diameters of the first portions 421 and 431.

Other equivalent embodiments can be carried out by the skilled person, for example by using a configuration of the sealing and counter-sealing rollers `` cantilevered '' illustrated in figure 9a, i.e. by positioning both the supports of each of the sealing rollers 42 and counter-sealing 43 in correspondence with the motor means of the rollers themselves, thus leaving the opposite zone completely free, ie the zone facing the line operator in which the discontinuous band 39 of the composite belt 100 normally passes when it is folded.

A further embodiment 90, illustrated in figure 9b, can be implemented using ultrasonic welding technology, in this case the sonotrode (or sonotrodes) 95 of the ultrasonic welding system (or systems) 92 would cooperate with the contrast roller 93 on which the welding blades 96a and 96b are arranged, said contrast roller can be made for use in a structure that can see it in a `` cantilever '' configuration, or it can be used in a structure that foresees to support it on both sides, as can be seen in figure 9b. Obviously in this last configuration there would always be the portion of roller 932 with the diameter 932â € ™ reduced compared to the first diameter 931â € ™ of the first portion of the contrast roller 931. In any case it is evident that the carriage contiguous to the The ultrasound unit would have no space limitations. In the preferred embodiment, the third transport 53 can be realized by an upper trolley 58 and a lower trolley 59. Both trolleys are equipped with suitable motor means 562, which are in common with the second transport system 52, and which are capable of giving the belt 581 of the upper carriage 58 and the belt 591 of the lower carriage 59 a linear speed of advancement equal to that of the belt 100. The two carriages 58 and 59 are also equipped with mechanical means, known, capable of clamping together the continuous band 38 of the belt 100. Furthermore, in order to increase the clamping capacity of the chain of blanks 100 carried out by the aforementioned carriages 58 and 59, one or both of the belts 581 and 591 can be of the `` under suction '' or `` vacuum '' type, that is, have the surface permeable to air, which connected to a source of sub atmospheric pressure with means known per se is able to increase the force from overall clamping applicable to the continuous band 38 of the belt 100 by the transport 53.

In the preferred embodiment, the two transport systems 52 and 53, as illustrated in Figure 4, have the purpose of feeding the belt 100, composed of the chain of blanks of absorbent articles 10, to the cutting station 60. To this end, the lower carriage 57 of the second transport system 52 and the lower carriage 59 of the third transport system 53 may have the drive roller 563 in common. In the embodiment described here, the drive roller 563 is placed in proximity to the cutting station 60 and feeds it with the composite belt 100.

The cutting station 60 can comprise a support structure 61 on which the cutting roller 62 (or knife) and the contrast roller 63 (or counter knife) are mounted. The two knife rollers 62 and counter knife 63 can be motorized by a motor means 65 which in the preferred configuration can be constituted by an electronically controlled servomotor which, in turn, can be mechanically connected to the knife roller 62 by means of a suitable homokinetic joint. , the knife roller 62 motorizes the roller against the knife 63 by means of a motion transmission system which can be of the gear type 64, where the gears, motor 641 and driven 642, are keyed respectively on the knife roller 62 and on the counter roller. knife 63.

As better illustrated in Figure 8, in the preferred embodiment, the knife roller carries on its surface at least one cutting blade 621.

Each cutting blade 621 cooperates with the counter-knife roller 63 on a corresponding contrast insert 631.

As known, the cutting edge 621 and the counter knife 63, in particular the contrast insert 631, must have peripheral speeds substantially equal to each other and equal to the feed speed of the composite tape 100.

Therefore the diameter of the roller against the knife 63 must be chosen so as to have a development of its circumference equal to an integer multiple of the transversal development 8 of the product 10 of Figure 2 in extended condition.

Obviously, what has been said makes it clear that the cutting station 60 is one of those components of the production line which must be subjected to format change operations when it is decided to produce an absorbent article of different dimensions (size change).

As can be seen from the image of figure 8, during the feeding phase of the cutting station 60, the composite tape 100 is stably held, without ever being abandoned, in fact both the continuous band (38) and the discontinuous band (39) of said belt (100) passing from said roller (563) of the transport means (50) to said contrast roller (63) of said cutting unit (60), carry out a curvilinear path before the continuous band (38) of said belt (100) is subjected to cutting action by means of the knife.

According to a preferred embodiment, as shown in Figure 8, the sealing action of the composite tape 100 can be further improved by making the aforementioned tape 100 travel an S-shaped path, both to the longitudinal portion (or strip). 38 and to the discontinuous longitudinal portion (or band) 39 of the belt 100.

The sealing action of the composite belt 100 can be made even more effective by ensuring that the permeable surfaces of the belts 571 and 591 are connected to a source of sub atmospheric pressure also in correspondence with the drive roller 563 and that the surface of the against knife 63 is capable of exerting a suction action. Said suction action is carried out in selected sectors of the circumference of the two rollers 563 and 63, as illustrated in Figure 8. In this way the two rollers, i.e. the drive roller 563 and the counter-knife roller 63, are able to respectively hold the lower surface and the upper surface of both the continuous band 38 and the discontinuous band 39 of the composite tape 100.

It is possible to maintain under suction a motor roller on which belts are wound using, for example, the belts identified with the Conducto® brand produced and marketed by the company GKD - Gebr. Kufferath AG, Metallweberstrasse no. 46, 52353 Dueren Germany. In this case, the drive roller 563 is drilled radially by holes 564 provided in its shell surface and arranged in rows that extend along the generatrices of the roller 563, each row of holes 564 leads to its respective manifold 565 which in turn is connected, by means of a suitable distributor 566, kept in a fixed position, to the aforementioned sub-atmospheric vacuum source (not shown in the drawings).

Similarly, the roller against the knife 63 is drilled in a radial direction by holes 632 provided in its shell surface and arranged in rows which extend along the generatrices of the roller 63, each row of holes 632 leads to its respective manifold 633 which, to in turn it is connected, by means of a suitable distributor 634, kept in a fixed position, to the aforementioned source of sub atmospheric vacuum (not shown in the drawings). In addition, the roller against the knife 63 can have recesses 635 on its surface where the thickest parts of the absorbent article are housed, ie the parts in which the absorbent material of the insert 20 is present.

Therefore, the belt 100 thus held thanks to the action exerted by the vacuum of the motor roller 563 and the counter-knife roller 63, is segmented by the blade 621 of the knife roller 62, in correspondence with the continuous band 38, into the plurality of disposable absorbent products 10 , which are in turn transferred by the counter-knife roller 63 to the equipment located downstream of the cutting station 60, which carry out the further operations of longitudinal and / or transversal folding of the absorbent article, as well as counting, grouping and product packaging.

According to a preferred embodiment, as shown in Figure 8, the knife roller 62 can have on its surface a shell 622, normally made of thermoplastic material, which is capable of gripping the edge of the continuous band 38 of the belt 100 which is it is created when the blade 621 has separated each absorbent article 10 from it.

Naturally, without prejudice to the principle of the invention, the details of construction and the embodiments may vary, even significantly, with respect to what is illustrated here purely by way of non-limiting example, without thereby departing from the scope of the € ™ invention as defined by the attached claims.

Claims (15)

CLAIMS 1. Device for welding and cutting a composite tape formed by a chain of blanks of absorbent sanitary products (100), which advances continuously in a longitudinal direction (A), and comprising a portion of continuous longitudinal tape (38) and a discontinuous longitudinal portion (39), said device comprising: - at least one welding station (40), in which said station comprises a sealing roller (42) which has a first portion (421) with a first diameter (421â € ™) on which at least one sealing blade (46a) is placed and 46b), a contrast counter-sealing roller (43) which has a first portion (431) with a first diameter (431â € ™) which cooperates with the at least one sealing blade (46a and 46b) acting as an abutment surface welding, - a cutting station (60) in which said station comprises a cutting roller (62) on which the cutting blade (621) is placed, a contrast roller (63) which cooperates with the cutting blade acting as a surface stop of the cut (631), - conveyor means (50) comprising at least one conveyor belt (52) adapted to transport the discontinuous longitudinal portion (39) of said composite belt (100) through said sealing unit (40), adjacent to said sealing roller (42) and to said counter-sealing roller (43), in which said at least one conveyor belt (52) feeds said cutting station (60). 2. Device according to claim 1, wherein in said at least one welding station (40) at least one of said sealing roller (42) and counter-sealing roller (43) has a second portion (422, 432) coaxial and adjacent to said first diameter (421, 431) with a second diameter (422â € ™, 432â € ™) smaller than the first diameter (421â € ™, 431â € ™). Device according to claim 1, wherein in said at least one welding station (40): - the sealing roller (42) has a second portion (422) coaxial and adjacent to the first portion (421) with a second diameter (422â € ™) smaller than the diameter (421â € ™) of said first portion (421), and - the counter-sealing roller (43) has a second portion (432) coaxial and adjacent to the first portion (431) with a second diameter (432â € ™) less than the diameter (431â € ™) of said first portion (431). 4. Device for welding and cutting a composite tape formed by a chain of blanks of absorbent sanitary products (100), which advances continuously in a longitudinal direction (A), and comprising a portion of continuous longitudinal tape (38) and a discontinuous longitudinal portion (39), said device comprising: - at least one welding station (90), in which said station comprises at least one ultrasonic welding unit (92) which cooperates with at least one sealing blade (96a and 96b) placed on a contrast roller (93) which has a first portion (931) with a first diameter (931â € ™), - a cutting station (60) in which said station comprises a cutting roller (62) on which is placed a cutting blade (621), a contrast roller (63) which cooperates with the cutting blade acting as a surface stop of the cut (631), - conveyor means (50) comprising at least one conveyor belt (52) adapted to transport the discontinuous longitudinal portion (39) of said composite belt (100) through said sealing unit (90), adjacent to said at least one ultrasonic welding unit (92) and to said contrast roller (93), in which said at least one conveyor belt (52) feeds said cutting station (60). 5. Device according to claim 4, wherein in said at least one welding station (90) said contrast roller (93) has a second portion (932) coaxial and adjacent to said first portion (931), with a second diameter ( 932â € ™) smaller than the first diameter (931â € ™). 6. Device according to any one of the preceding claims, in which the at least one conveyor belt (52) is connected to at least one source of sub atmospheric pressure. 7. Device according to claim 6, wherein said conveyor means (50) comprising a first lower belt (57) and a second upper belt (56) adapted to grip between their respective mutually facing surfaces the discontinuous longitudinal portion (39) of said composite tape (100). 8. Device according to any one of the preceding claims, wherein said conveyor means (50) comprising at least one roller (563) placed in proximity to the contrast roller (63) of said cutting unit (60), arranged in such a way that it is the continuous longitudinal belt portion (38) which the discontinuous longitudinal belt portion (39) of the belt (100) passing from said roller (563) of the transport means (50) to said contrast roller (63) of said cutting (60) carry out a curvilinear path before the aforementioned continuous longitudinal belt portion (38) of said belt (100) is subjected to cutting action by means of the knife (621). 9. Device according to claim 8, wherein the at least one roller (563) of said transport means (50) comprising gripping means (632, 633) of said composite belt (100), said gripping means (632 , 633) preferably comprising gripping means at sub atmospheric pressure. Device according to any one of the preceding claims, wherein said contrast roller (63) of said cutting station (60) comprises on the external surface recesses (635) suitable for receiving the thicker parts of said composite tape (100, 10). Device according to any one of the preceding claims, wherein said contrast roller (63) of said cutting station (60) comprises gripping means (632, 633) of said composite tape (100, 10), said gripping means (632, 633) preferably comprising gripping means at sub atmospheric pressure. 12. Method for the production of sanitary wares of the pre-closed panty type (10) comprising the steps of: - folding in two longitudinally a composite belt (100), formed by a chain of blanks of absorbent sanitary products (10), which advances continuously in a longitudinal direction (A), said belt comprising a portion of continuous longitudinal belt (38) and a longitudinal portion of discontinuous tape (39), the continuous portion comprising the waist regions (9 and 15), the discontinuous portion comprising the inguinal region (3) placed between the two waist regions (9, 15) and the leg openings (11), - welding (40) said composite strip (100) in the continuous longitudinal portion (38) with welding lines transversal (13) to the longitudinal direction of advancement (A) respectively spaced from each other by a pitch equal to the width (8) of said hygienic-sanitary article designed to form the waist circumference (7, 5) and the opening of the legs (11) of the hygienic-sanitary article (10), - conveying the composite tape (100) through the welding station (40) while maintaining the positive grip of the discontinuous portions (39) of said composite tape (100), - feeding the cutting station (60) with said composite belt (100) while maintaining the positive grip of the discontinuous longitudinal portions (39) of said composite belt (100), - cutting said composite tape (100) in the continuous longitudinal portion (38) with cuts (12) transversal to the longitudinal direction (A) of advancement respectively spaced from each other by a pitch equal to the width (8) of said sanitary article (10 ) suitable for separating the individual sanitary items from each other (10). Method according to claim 12, wherein in the transport and feeding phases of the composite belt (100) the discontinuous longitudinal portion (39) of said belt (100) is held positively gripped by at least one pair of conveyor means (56 and 57 ) facing each other. Method according to claim 12 or claim 13, wherein in the stages of conveying and feeding the composite belt (100) the discontinuous portion (39) of said belt (100) is maintained positively gripped by means of gripping means at sub atmospheric pressure. Method according to any one of claims 12 to 14, wherein in the cutting step (60) thicker parts of the discontinuous portion (39) of the composite tape (100) are received and held positively by means of pressure gripping means sub atmospheric in respective recesses (635) present on the external surface of said contrast roller (63).