The present disclosure relates to the techniques for folding web materials.
The disclosure has been developed with particular attention paid to its possible application to the folding of web materials used in the production of sanitary articles.
In numerous sectors of the art there arises the need to fold web materials moving in the longitudinal direction of the web.
For instance, in the packaging industry machines are known referred to as “flow-pack” (or “ffs”, acronym for “form-fill-seal”), where a film winding material gives rise to a closed tubular semifinished product obtained by sealing together, so as to form a so-called longitudinal “fin”, the edges of the web material after it has been closed on itself in a device commonly referred to as “former”. An example of such a former is described in the U.S. Pat. No. 4,761,937.
In the production of sanitary articles it is altogether common practice to use folding devices substantially constituted by a sort of plough share over which a web that is advancing is run and folded in a V-shape, without any interruption of its movement of advance. Such a device is illustrated, for instance, in the U.S. Pat. No. 3,066,932.
The inventors have noted that folding devices of a conventional type end up being mostly unusable in the case where the web material is, for instance, a web material W of the type schematically illustrated in
A situation of the type illustrated may be found, for example, during execution of operations of folding of so-called side panels of sanitary articles that can be worn as a pair of pants. Making the fold of a material W, as schematically illustrated in
To these considerations it should also be added the fact that, in particular in the production of sanitary articles, webs like the web W illustrated in
Moreover, in the case where extremely thin and hence rather delicate web materials are used (consider, for example, films of nonwoven fabric of extremely low substance, which find increasing use in the sector of sanitary articles), the folding operation can become critical even when the web material has a regular and constant profile, presenting as a normal web. In this case, the interaction of the folding blade or other active element of the folding device with a very delicate material runs the risk of leading to undesirable damage of the material itself, also taking into account the fact that in sectors like the ones considered involve extremely high automatic production rates, indeed, increasingly high production rates, to which there corresponds a constant increase in the speed of advance of the webs that are to undergo the folding operation.
The need to have available improved folding solutions is hence felt not only in relation to web materials with an irregular profile, for example, a sawtooth profile, as illustrated in
The object of the present invention is to provide an answer to said need.
According to the invention, said object is achieved thanks to a device having the characteristics recalled specifically in the ensuing claims. The invention also regards a corresponding process. 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 an in-depth understanding of the embodiments. The embodiments can be produced 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 herein so as not to render various aspects of the embodiments obscure.
The 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 different points of the present description do not necessarily refer to one and the same embodiment. Furthermore, particular conformations, structures, or characteristics can 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.
The drawing of
In particular, when a torsion is imparted on the lamina T such as to bring its opposite ends to be rotated with respect to each other through 180° about the axis XT:
From an observation of half of the (initially top) face U, which is hatched in the part in the foreground in
Various embodiments are based upon the recognition of the fact that, with reference by way of non-limiting example to the web W of
In this way (as schematically represented in
The folding function represented schematically in
In particular, the reference 10 designates a plate that is to constitute a surface of sliding (from left to right, as viewed in
The reference number 20 designates, instead, a belt conveyor set alongside the plate 10 so as to be practically coextensive with the edge 100. The conveyor 20 can be of the type commonly used in the automatic-packaging industry and also in the sector of the production of sanitary articles. It may, for instance, be a strong belt made of flexible plastic material (possibly provided with a textile reinforcement: the corresponding technological solutions are extremely numerous) forming an endless loop by running over two mutually parallel end rollers 30 and 40, where at least one of them (for example, the roller 40) is assumed as being moved by a power drive 80, of a known type.
When the power drive 80 is active, the top branch of the belt travels upwards along its path running over the roller 30 (which is assumed as here turning in a clockwise direction) and then advances towards the roller 40.
The condition of mounting of the rollers 30 and 40 is such that, in the passage from the roller 30 to the roller 40 situated at the opposite end of the conveyor, the belt 20 is subject to a helical movement of torsion through 180° around a median axis X20 thereof, substantially aligned with the edge 100 of the plate 10.
In this way, what in the proximity of the roller is the top branch of the belt 20, which is to receive and draw along on it the toothed parts W2 of the web W—which are currently co-planar with the core part W1—, at the opposite end of the conveyor (in the background of
The observation in sequence of the three cross-sectional views of
In particular, if we assume feeding to the belt conveyor 20 starting from its end set upstream (on the left in
Once approximately half-way of the longitudinal development of the conveyor 20 is reached (see the cross-sectional view of
Once the belt conveyor 20 arrives in the proximity of the roller 40 (see cross-sectional view of
The device illustrated makes it possible to form, in a web element W that is advancing, a fold along a line of fold W3 oriented in the direction of advance of the belt, which brings a first portion (e.g., W1) and a second portion (e.g., W2) of the web element W, which are initially situated on opposite sides of the line of fold W3 (see
The person skilled in the sector will appreciate that to provide the surface of feed 10 it is possible to resort to solutions different from a sliding plate; for instance, in various embodiments, the surface of feed 10 can be defined by one of the two branches of a belt conveyor of the type commonly used in the automatic-packaging industry and also in the sector of production of sanitary articles.
The reference 50 designates an array of holes, which may be provided, according to criteria in themselves known, in the portion of the conveyor belt 20 that is to co-operate with the crest parts W2 subjected to folding.
In various embodiments, the array o holes 50 may concern only the area on which the crest parts W2 of the web come to rest.
The array of holes or openings 50 is to co-operate with a suction box 60 set within the belt conveyor 20 in a condition of intermediate extension between the two branches of delivery and return of the conveyor itself. The suction box 60 is provided with suction mouths 61 and can be set in communication with a source of subatmospheric pressure 70 (a so-called “vacuum pump”). The source 70 has the function of inducing a flow of aeriform from the external environment towards the inside of the suction box 60, said flow passing through the openings 50 of the belt and the suction mouths 61 from the suction box 60.
According to a solution known in the sector of automatic packaging and in the sector of manufacture of sanitary products, the so-called “vacuum cleaner effect” thus induced means that the air recalled from the surrounding environment into the suction box 60 performs an action of recall such as to withhold against the conveyor belt 20 the crest parts W2 of the web material W preventing detachment thereof from the conveyor belt and their undesirable “fluttering” during execution of the folding operation.
Said effect of withholding and providing a sure guide in the course of execution of the folding operation can be achieved also in the case of a web material having a regular profile (hence with constant section) made, however, of a particularly delicate material, for instance, a nonwoven fabric with particularly low substance.
In various embodiments, the suction box 60 can comprise a single suction chamber. In various embodiments, the suction box can comprise distinct chambers, each connected to a respective line for application of a subatmospheric pressure (vacuum line).
As may be inferred from
In various embodiments, the belt 20 has, however, a greater extension, as represented in the drawings. In various embodiments, this enables the action of grip of the belt on the web material W subjected to folding to be rendered more regular and continuous, preventing any possible of uncovered areas from accidentally arising.
In various embodiments, the structure described herein is suited also to being produced in a paired or “twin” form using two devices of the type illustrated in
Of course, without prejudice to the principle of the invention, the details of production and the embodiments may vary, even significantly, with respect to what is 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 |
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TO2010A000143 | Feb 2010 | IT | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IB11/50527 | 2/8/2011 | WO | 00 | 8/21/2012 |