Patent Application
20150209190
The present description relates to a cutting device that can be used in the production of sanitary articles, such as, for example, nappy-pant products of the pre-closed type.
The reference to this specific field of application must not, on the other hand, be interpreted in a sense that limits the scope of the invention.
A common technique for the production of sanitary products, of the pre-closed or pre-fastened type, that can be worn as pants, normally referred to as “training pant” or “pull-ups”, consists in providing a composite web formed by a continuous chain of blanks of product aligned so as to have the transverse axis of each individual absorbent article coinciding with the direction of movement of the web itself. The continuous composite web is folded in two about said transverse axis so as to set the opposite longitudinal edges of the web on top of one another. The two flaps of the composite web thus set on top of one another are connected together with welding lines so as to define the openings for the waist and for the legs of each absorbent article. The continuous chain of blanks, at the welds, is subsequently subjected to a cutting operation to divide the finished products from one another.
This particular methodology of production is normally identified with the term “cross direction” (or CD) to distinguish it from the more traditional form of production, referred to as “machine direction” (or MD), which forms the absorbent articles while they travel with their own longitudinal axis parallel to the direction of production.
An example of a method of production of absorbent sanitary products of the CD type is described in the documents Nos. EP-A-1 013 251 and IT-0001379452, filed in the name of the present applicant.
In CD methods, it is necessary to ensure proper positioning of the transverse welds of each product so as to define properly the openings for the waist and for the legs of each individual nappy. Moreover, it is important for the cutting line envisaged for dividing the individual products from one another to be properly positioned at the welds made between two adjacent absorbent products and it is even more important for both the welds and the cuts to present a constant angular position with respect to the direction of advance of the web; i.e., in other words, at least the cuts must always present the same angular relation with respect to the edges of the composite web.
According to the known art, to obtain sanitary articles with the welds and the cuts in a proper phase relation with respect to one another and with an angular relation with respect to the edges of the article constant in time, there becomes necessary extremely complex and costly equipment, where said operations of welding and cutting are performed on a single roller run over which is the continuous web made up of the blanks of the individual absorbent articles.
It is obvious to the person skilled in the branch that a solution of this sort brings with it problems that are difficult to solve, such as for example the complexity of the apparatus and the low flexibility in the change of the format of the articles, with the consequent rise in the operating costs. The low flexibility to the change of format is basically due to the fact that the diameter of the roller must be chosen so that the circumference is an integer multiple of the transverse development of the absorbent product that is being produced. Consequently, as the article changes, the transverse development of the absorbent article changes, and accordingly the diameter of the roller changes. As a result, the entire welding and cutting unit must be replaced.
The complexity of the known equipment derives from the fact that the cutting and welding tools must be accommodated around a single roller that functions as contrast roller both for the welding operation and the cutting operation. Consequently, said roller must be of large diameter to be able to house on its periphery both the welding mechanisms and the cutting devices and, on account of the delicacy of both processes, said roller must present an equally high precision that raises the costs thereof.
The foregoing is aggravated by the fact that to be able to carry out a weld of adequate mechanical characteristics it is necessary to heat the composite web formed by the continuous chain of blanks. For this purpose, normally said heating is obtained by inserting resistances in the areas that are to be welded, which are obviously also cutting areas. On account of the large diameter of the contrast roller, and hence on account of the resulting considerable mass, management of the temperature of said contrast areas presents problems that are difficult to solve and lead to the reduction of the working life of the welding and cutting tools, which, inevitably, are affected by the variations in temperature and hence by the consequent dimensional variations of the common contrast element.
The object of the present invention is to improve the technique for the production of sanitary articles of the pre-closed type that can be worn as pants so that the opposite transverse edges of each article always maintain the proper relation of shape and phase with the corresponding transverse welding line.
According to the present invention, said object is achieved by equipment and by a method forming the subject of Claims 1 and 7.
The claims form an integral part of the technical teaching provided herein in relation to the invention.
The invention will now be described, purely by way of non-limiting example, with reference to the annexed drawings, in which:
Illustrated in the ensuing description are various specific details aimed at providing an in-depth understanding of the embodiments. The embodiments may be obtained 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 illustrated or described in detail so that various aspects of the embodiments will not be obscured.
Reference to “an embodiment” or “one embodiment” in the framework of the present description is intended to indicate that a particular configuration, structure, or characteristic described in relation to the embodiment is comprised in at least one embodiment. Hence, phrases such as “in an embodiment” or “in one embodiment” that may be present in various points of the present description do not necessarily refer to one and the same embodiment. Moreover, particular conformations, structures, or characteristics may be adequately combined in one or more embodiments.
The references used herein are provided merely for convenience and hence do not define the sphere of protection or the scope of the embodiments. Consequently, the definitions “front” or “rear” referring to the absorbent sanitary article depend only upon the final use of the product itself, i.e., upon how it is worn by the user, whereas the definitions “top” or “bottom” regarding possible elements present in one or more embodiments described depend only upon the viewing point of the observer with respect to the drawings annexed to the present document, without thereby limiting the principle and/or the scope of the invention.
With reference to
In
In basic terms, the product 10 is made up of a chassis 1, or outer part of the absorbent product, which, during use of the sanitary article, supports the absorbent insert 2 and keeps it in contact with the body of the user.
Nappies of this sort may present shapes and structures different from one another; consequently, the shape and structure of the absorbent nappy that is described in the sequel of the present document is to be understood merely by way of example, to enable a better appreciation of the advantages of the present invention.
The absorbent product represented in
The elastic elements 16 extend along the front waist edge 5 and rear waist edge 7 and are designed to elasticate the opening for the waist 14. The elastic elements 17 are designed to elasticate the openings for the legs 11.
The two sheets 4 and 5 constituting the chassis 1 are normally made of non-woven fabrics that may have undergone treatments that render them impermeable to liquids so as to contain any possible leakage of liquids and prevent any possible contamination of the clothes of the user with which the chassis 1 is in contact.
The elastic materials 16 and 17, in turn, can be chosen from among the multiplicity of materials available on the market, such as, for example, strips made of synthetic rubber, manufactured by Fulflex, or yarn made of Lycra®, manufactured by Invista.
In the absorbent product, represented in
One of the functions of the elastic elements 16 and 17 of the chassis 1 described above is that of keeping the absorbent insert 2 in the proper working position, even when it gets heavy because it has absorbed the body fluids.
The two sheets 4 and 5 constituting the chassis 1 and said elastic materials 16 and 17 are rendered fixed by means of adhesives and/or thanks to welds performed with heated rollers or ultrasomic systems.
The absorbent insert 2 has a structure in which there may be recognized (in addition to various other accessory elements):
On the absorbent product 10, and in particular on the absorbent insert 2, there may be present other characteristic elements that contribute to enhancing the characteristics of wearability and absorbance thereof, such as for example the so-called “cuffs” or elasticated sides 25 set at the sides of the absorbent core 20 with the function of lateral containment of body fluids.
For a more detailed description of the elements listed above and of other elements, well known to persons skilled in the art, the reader is referred to the extensive literature existing on the subject, such as for example the U.S. Pat. No. 4,704,116, granted on Nov. 3, 1987 to Enloe.
In a possible embodiment, as highlighted in
As highlighted in
As is evident to the person skilled in the art, the representations of
Schematically represented in
An example of equipment and of method 30 suitable for making a fold of this sort is described in the document No. TO2011A001085, filed in the name of the present applicant.
After the operations of folding and closing, the continuous composite web is subjected to operations of cutting along the transverse lines 12 to form the individual product 10.
It will be appreciated from
From what has been said, it will hence be appreciated how problematical it is to ensure that during the operations of welding and cutting of each product 10 there is always kept an accurate phase relation between the transverse welds 13 and the cuts 12, as well as a constant angular relation between said transverse welds 13 and the cuts 12 with respect to the waist edges 5 and 7 of each absorbent article 10.
Schematically illustrated in
In the embodiment exemplified, the apparatus 70 is made up of the equipment 40, which is able to provide transverse welding lines 13, designed to define the waistline and the openings for the legs in each pre-closed absorbent sanitary article 10 of the pant type, such as for example the one represented in
In the preferred embodiment, as illustrated in
The web of blanks 100 is made to pass, in the longitudinal direction of advance A, between the welding roller 42 and the counter-welding roller 43, which turn so as to have the respective tangential speeds substantially identical to one another and equal to the speed of linear advance of the chain of blanks 100.
The welding roller 42 and counter-welding roller 43 are driven in a known way, for example by a single motor drive with the provision of transmission means, or else, according to a currently preferred solution, illustrated in
In the device described herein, the action of welding is obtained with the combined application of pressure and heat. For this purpose, both of the rollers carry mounted within them (according to a configuration in itself known and used for example in “flow-pack” packaging machines) heating resistors and means for controlling the temperature.
The pressure between the two rollers is guaranteed by means in themselves known, such as for example pneumatic, or hydraulic, or mechanical systems, which are well known by persons skilled in the field and are not illustrated in the figures for simplicity of representation.
The roller 42 that has the function of welding roller is provided along its periphery with projecting welding blades 46a and 46b, transverse to the direction of advance of the composite web 100, in other words, substantially aligned with the axis of rotation X4 of the welding roller itself 42. In the preferred embodiments illustrated in the present document, the welding blades 46a and 46b form with any generatrix of the cylinder of the welding roller parallel to the axis of rotation X4 an angle of 3° to 4°.
The roller 43 that has the function of contrast roller has, instead, a completely smooth surface of the mantle.
As is known, and as is clearly highlighted in
In the preferred embodiment, as illustrated in
In the preferred embodiment, as highlighted more clearly in
In the preferred embodiment, also the second conveyor 52 may be provided by a top carriage 56 and a bottom carriage 57. Both of the carriages are equipped with appropriate motor means 562 that are able to bestow on the belts 561 and 571 of the two respective carriages 56 and 57 a linear speed of advance equal to that of the web 100 and are able in turn to keep the discontinuous parts 39 of the web 100 gripped together thanks to mechanical means in themselves known.
In order to increase the gripping capacity of the discontinuous parts of the web 100, also in this case, one or both of the belts 561 and 571 belonging, respectively, to the top carriage 56 and to the bottom carriage 57 of the second conveyor 52, may be of the “suction” or “vacuum” type; i.e., they may have the surface permeable to air, which, being connected to a source of subatmospheric pressure with means and techniques well known to persons skilled in the sector, increases the overall gripping force that the conveyor 52 is able to apply to the web 100. The conveying system 52 grips the discontinuous band 39 of the web 100 leaving the folding system 30 and accompanies it as far as the cutting assembly 60, traversing the welding station 40 without ever abandoning the discontinuous band 39 of the web 100. Traversal of the welding station 40 by the second conveyor 52, as is clearly evident in
In the preferred embodiment, the third conveyor 53 may be provided by a top carriage 58 and a bottom carriage 59. Both of the carriages are equipped with appropriate motor means 562, which are in common with the second conveying system 52 and are able to bestow on the web 581 of the top carriage 58 and the web 591 of the bottom carriage 59 a linear speed of advance equal to that of the web 100. Also the two carriages 58 and 59 are provided with mechanical means, in themselves known, which are able to grip the continuous band 38 of the web 100 between them. Moreover, in order to increase the gripping capacity of the chain of blanks 100 provided by said carriages 58 and 59, one or both of the belts 581 and 591 may be of the “suction” or “vacuum” type; i.e., they may have the surface permeable to air, which, by being connected to a source of subatmospheric pressure with means in themselves known, is able to increase the overall gripping force that can be applied to the continuous band 38 of the web 100 by the conveyor 53.
In the preferred embodiment, the two conveying systems 52 and 53, as illustrated in
The cutting station 60 may comprise a supporting structure 61, on which the cutting (or blade) roller 62 and the contrast (or counterblade) roller 63 are mounted. The blade roller 62 and counterblade roller 63 may be motor-driven by a drive means 65 that in the preferred configuration may be constituted by an electronically controlled servo motor, which, in turn, may be mechanically connected to the cutting or blade roller 62 by means of an appropriate constant-velocity joint. Furthermore, the blade roller 62 drives the counterblade roller 63 by means of a system of transmission of motion that may be of the gear type 64, where the gears, i.e., the drive gear 641 and driven gear 642, are fitted, respectively, on the blade roller 62 and on the counterblade roller 63.
As illustrated more clearly in
Each blade 621 co-operates with the counterblade roller 63 on a corresponding contrast insert 631.
As is known, the blade 621 and the counterblade roller 63, in particular the contrast insert 631, must have peripheral speeds that are substantially the same as one another and equal to the speed of feed of the composite web 100.
Consequently, the diameter of the counterblade roller 63 must be chosen so as to have a development of the circumference equal to an integer multiple of the transverse development 8 of the product 10 of
Obviously, what has been said makes it clear that the cutting station 60 is one of those components of the production line that must undergo the operations of change of format when it is decided to produce an absorbent article of different dimensions (change of size).
As may be appreciated from the representation of
According to a preferred embodiment, as illustrated in
The action of gripping of the composite web 100 may be rendered even more effective by causing the permeable surfaces of the belts 571 and 591 to be connected to a source of subatmospheric pressure also in an area corresponding to the drive roller 563 and causing also the surface of the counterblade roller 63 to be able to exert an action of suction. Said suction action is provided in selected sectors of the circumference of the two rollers 563 and 63, as illustrated in
It is possible to keep under suction a drive roller over which belts are run using, for example, the belts identified by the trademark Conducto® produced and marketed by the firm GKD-Gebr. Kufferath AG, Metallweberstrasse No. 46, 52353 Dueren, Germany. The drive roller 563, in this case, is perforated in a radial direction with holes 564 made in its mantle surface and arranged in rows that extend along the generatrices of the roller 563, each row of holes 564 coming under a respective manifold 565, which is in turn connected, by means of an appropriate distributor 566, held in a fixed position, to said source of subatmospheric pressure (not represented in the drawings).
Likewise, the counterblade roller 63 is perforated in a radial direction by holes 632 made in its mantle surface and arranged in rows that extend along the generatrices of the roller 63, each row of holes 632 coming under a respective manifold 633, which is in turn connected, by means of an appropriate distributor 634, held in a fixed position, to said source of subatmospheric pressure (not represented in the drawings). In addition, the counterblade roller 63 may present, on its surface, recesses 635, housed in which are the parts of larger thickness of the absorbent article, i.e., the parts in which the absorbent material of the insert 20 is present.
Consequently, the web 100 thus gripped thanks to the action exerted by the vacuum of the drive roller 563 and of the counterblade roller 63, is segmented by the blade 621 of the cutting roller 62, in an area corresponding to the continuous band 38, into the plurality of disposable absorbent products 10, which are in turn transferred by the counterblade roller 63 to the equipment set downstream of the cutting station 60, which carries out the further operations of longitudinal and/or transverse folding of the absorbent article, as well as counting, grouping, and packaging the products.
According to a preferred embodiment, as illustrated in
Of course, without prejudice to the principle of the invention, the details of construction and the embodiments may vary, even significantly, with respect to what has been illustrated herein purely by way of non-limiting example, without thereby departing from the scope of the invention as defined by the annexed claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| TO2012A000209 | Mar 2012 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2013/051657 | 3/1/2013 | WO | 00 |
