Patent Description:
More precisely, the invention relates to a transversal cutting unit which can be used for the packaging of sanitary-absorbent articles, such as for example diapers, diaper-panties, feminine sanitary towels, etc..

Flow-pack packaging is one of the most popular systems for packaging a large variety of consumer products.

In flow-pack packaging systems, a continuous packaging film, typically of plastic material, is unwound from a reel and is folded into the shape of a continuous tubular member that surrounds the products to be packaged and advances in a machine direction together with the flow of products to be packaged. The continuous tubular member of packaging material is closed by means of a continuous longitudinal seal that joins the opposite longitudinal edges of the packaging film and by means of transverse seals spaced apart from each other in the machine direction that seal the continuous tubular member at opposite sides with respect to the products that must be included in a single package.

A flow-pack packaging machine typically comprises:.

In accordance with a per se known technique, the packaging of absorbent sanitary articles, such as, for example, diapers, is achieved by wrapping the folded articles in a continuous film generally of polyethylene, by means of a suitable folding nozzle. The individual articles are transported in a machine direction within the continuous film that surrounds them. In the known solution, a welding station is arranged to seal the ends of the single package being created and, at the same time, a blade integrated in the same welding station separates the individual packages from each other. In a subsequent step of the method, the single package is carried to the step that is useful for multi-product packaging in larger bags.

Known solutions envisage that the packaging machine is configured to produce strips of single packages, each including one or more products, wherein the individual packages are connected to each other and pre-engraved along the transverse sealing, to facilitate subsequent detachment of the single package. <CIT> discloses a device which permits, in the same station to perform either a transversal cut or a series of perforations. It has a cutting blade and a perforating blade which can alternatively act against a cylinder with counter tools. A controller varies the phase between the different tools.

The present invention starts from the desire to make a cutting unit, an apparatus, and a relative method, arranged to make both a plurality of individually separated packages, and continuous and pre-engraved strips of individual packages, with the possibility of carrying out an automatic separation of the packages every n articles, where n varies according to production requirements.

The object of the present invention is to provide a device that satisfies the requirements indicated above.

According to the present invention, this object is achieved, by a cutting machine, an apparatus and a method having the characteristics forming the subject of claims <NUM> and <NUM>. Preferred embodiments of the invention form the subject of the dependent claims.

The claims form an integral part of the disclosure provided here in relation to the invention.

The present invention will now be described in detail with reference to the attached drawings, given purely by way of non-limiting example, wherein:.

With reference to <FIG>, <FIG>, numeral <NUM> indicates a packaging apparatus of the horizontal flow-pack type.

In a packaging apparatus intended to form packages of the type currently referred to as "flow-pack", a conveyor is configured to advance a flow of articles to be packaged along a machine direction MD. In accordance with a preferred embodiment, the apparatus <NUM> is arranged to advance the articles along a substantially horizontal direction.

In one or more embodiments, the apparatus <NUM> is arranged to package a flow of absorbent sanitary articles, such as for example diapers, diaper-panties, feminine sanitary towels, etc..

The packages C are formed by arranging a continuous flow of articles fed to an inlet end of the apparatus <NUM> and by a continuous packaging film fed by an unwinding assembly of any known type.

According to widely known criteria, starting from the continuous film, a continuous envelope T of substantially tubular shape is formed, which surrounds the articles to be packaged, by means of a forming device configured to fold the continuous packaging film.

The continuous envelope T is advanced towards a longitudinal sealing station whose function is essentially to seal the longitudinal edges of the continuous envelope between two consecutive articles. According to a solution known per se, the sealing station may comprise a glue applicator designed to apply a layer of adhesive material along the longitudinal edges of the envelope T to be sealed.

<FIG> illustrates a preferred embodiment of an apparatus <NUM> according to the invention. In <FIG>, the articles are transported along the machine direction MD from right to left. <FIG> does not show the details relating to the unwinding assembly, the forming device and the longitudinal sealing station, as these details may be made according to the prior art.

In accordance with a further characteristic of the invention, the continuous tubular envelope T is advanced by means of automated transport means <NUM> towards a transversal welding unit <NUM> whose function is essentially to flatten the continuous envelope T in the spaces comprised between two consecutive articles, forming welding areas S in these spaces intended to hermetically separate the articles constituting a single package.

As illustrated in <FIG>, the transversal welding station <NUM> may be composed of a support structure <NUM> where a pair of counter-rotating rollers is installed, in particular, a welding roller <NUM> and a contrasting roller <NUM>. The rollers <NUM>,<NUM> are actuated, in a known way, for example, by a single motorization with the arrangement of transmission means, or by means of two independent motorizations constituted by two servomotors electronically controlled between them.

In one or more embodiments, the welding action is achieved with the combined application of pressure and heat. To this end, both the rollers <NUM>, <NUM> have heating resistors and temperature control means mounted inside them (according to a per se known configuration).

In one or more embodiments, as in the one illustrated in <FIG>, the transversal welding unit <NUM> comprises a first welding element <NUM> and a second welding element <NUM> movable with respect to each other according to a second straight direction perpendicular to the first machine direction MD, between an open position and a closed position. The welding elements <NUM>,<NUM> may be configured to carry out ultrasonic welding.

According to the invention, the apparatus <NUM> comprises a transversal cutting unit <NUM> that is separate and arranged downstream of the welding unit <NUM>, with reference to the machine direction MD.

As illustrated in <FIG>, <FIG>, <FIG>, the cutting unit <NUM> comprises a pair of active rotary elements <NUM> positioned at a respective side of the continuous envelope T, and configured to rotate around a respective axis I, II. In accordance with the example of horizontal packaging apparatus <NUM>, the rotary elements are respectively positioned above and below the continuous envelope T.

In one or more embodiments, the transversal cutting unit <NUM> may comprise a support structure <NUM> on which the pair of active rotary elements <NUM> are mounted.

The pair of active rotary elements <NUM> essentially consists of a cutting roller <NUM> (or knife) and a contrasting roller <NUM> (or counter-knife) driven in rotation by motor means (not shown).

<FIG> is a schematic view on an enlarged scale illustrating a preferred embodiment of the transversal cutting unit <NUM>. In accordance with the illustrated embodiment, the first rotary element (cutting roller <NUM>) carries at least one cutting element <NUM> on its surface, to perform a cutting operation at a welded area S of the continuous envelope T, which advances along the welding unit <NUM> and cutting unit <NUM>. Preferably, the cutting roller <NUM> has four cutting elements <NUM> spaced at <NUM>° along the circumference of the cutting roller <NUM>.

Again with reference to <FIG>, the second active rotary element (contrasting roller <NUM>), which acts as a contact surface for the cut, has a plurality of sections with grooves <NUM>, alternating with a plurality of solid sections <NUM>. As is evident from the following description and from the attached drawings, each section with grooves <NUM> has a plurality of hollow portions <NUM>, each shaped so as to create a groove with respect to the continuous outer surface of the roller <NUM>, while each solid section <NUM> has a regular continuous outer contact surface for cutting. The contrasting roller <NUM> may be made as a monolithic body with integrated hollow portions <NUM>.

It should be noted that the sections with grooves and solid sections <NUM>, <NUM> are alternated at a constant pitch along the circumference of the contrasting roller <NUM>. Therefore, during operation, each cutting element <NUM> cooperates with the contrasting roller <NUM> on a corresponding section with grooves or solid section <NUM>, <NUM>.

Thanks to the characteristics indicated above, during operation, when a cutting element <NUM> acts on a solid area - solid section <NUM> - a clean cut is made between two consecutive articles, thus separating the packages C. Conversely, when a cutting element <NUM> acts on a region with grooves - section with grooves <NUM> - an engraving is made between two consecutive articles, without separating the articles, so as to create a segment of a plurality of consecutive articles. A transversal engraving is therefore formed between two consecutive articles, designed to favor a subsequent separation of the articles. The segments may thus be made of a certain desired length (a certain number of consecutive engraved articles). Note that the expression "desired length" means that it is possible to make batches of segments of articles of one length and batches of segments of another length different from the previous one, for example, groups of segments of three articles and groups of segments of five articles.

As previously indicated, the rollers <NUM>, <NUM> are driven in rotation by motor means not shown in the drawings. In accordance with the invention, the motor means comprise independent electronically-controlled servomotors connected, respectively, to the cutting roller and to the contrasting roller.

In accordance with an additional characteristic of the invention, the apparatus <NUM> comprises an electronic control device E (illustrated in <FIG>) programmed to vary the phase between the cutting roller <NUM> and the contrasting roller <NUM>. The expression "vary the phase" means a variation of the relative angular position between a cutting element <NUM> and a section with grooves/solid sections <NUM>,<NUM>, during an operating cycle. In this way, it is possible to vary the frequency with which the contact of a cutting element <NUM> occurs with a solid section <NUM> and the contact of said cutting element <NUM> with a section with grooves <NUM>, so as to vary pre-incision cuts and clean cuts of the continuous envelope T that wraps the articles, in a variable way according to the production requirements. In one or more embodiments, the control device E is programmed to automatically control the contrasting roller <NUM> in acceleration or deceleration with respect to the cutting roller <NUM>, so as to vary the length of the segments of consecutive articles with engravings between one article and another. Thanks to these characteristics, article segments may be made of variable lengths without interrupting the production process. It should be noted that <FIG> illustrates an operating step of operation wherein the cutting unit is controlled to produce a plurality of articles with cut and separated packages C.

For correct operation, the cutting roller <NUM> must have a peripheral speed substantially equal to the feed speed of the continuous envelope T. The contrasting roller <NUM> will, instead, have a variable peripheral speed, substantially corresponding to a multiple integer of the pitch between the alternating sections <NUM>, <NUM> and close to the feed rate of the packages through the cutting unit <NUM>, to achieve the separation of the packages C or the continuous strip of pre-engraved packages C.

The description and attached drawings refer to a transversal cutting unit <NUM>, and to a related apparatus <NUM>, arranged to cut/engrave the continuous envelope T including a plurality of articles mutually spaced apart at a constant pitch. However, it should be noted that the invention is equally applicable for cutting/engraving applied directly to a continuous chain of articles still without any packaging envelope.

More generally, in the context of the overall apparatus <NUM>, the electronic control device E is, furthermore, configured to synchronize the operation of the transversal welding unit <NUM> and of the cutting unit <NUM>, so as to carry out the welding and the cutting (or pre-incision) of packages C in a single apparatus <NUM>. In this regard, in one or more embodiments, as in the one illustrated in <FIG>, a stabilization unit <NUM> of the packages C is interposed between said welding unit <NUM> and said cutting unit <NUM>, comprising:.

In one or more embodiments, the operation of the forming of the packages C is continuous, as the envelope T may undergo variations in speed, but it never stops during operation to carry out the welding and cutting operations.

In a preferred embodiment, the transversal cutting unit <NUM> has rollers <NUM>, <NUM>, which are rotated in opposite directions. This causes a circular movement in opposite directions of the rollers <NUM>, <NUM>, which brings, each time, a cutting element <NUM> into contact with a section with grooves <NUM> or with a solid section <NUM>, respectively, to carry out the pre-incision without separating the articles or the cut of the envelope E with separation.

As previously indicated, the alternating grooves and solid sections <NUM>, <NUM> are arranged at a constant pitch along the circumference of the contrasting roller <NUM>.

<FIG> shows a schematic view on an enlarged scale of the contrasting roller <NUM>. For each section with grooves <NUM>, a plurality of hollow portions <NUM> are provided, aligned along a transversal direction with respect to the machine direction MD, arranged to carry out the required pre-incision. Preferably, the hollow portions <NUM> are circular in shape.

In accordance with another preferred characteristic of the invention, the position of the hollow portions <NUM> varies from one section with grooves <NUM> to another, so that it does not come into contact with the cutting element <NUM> in the same way, so as to limit and make the wear of the cutting element <NUM> uniform. With reference to the embodiment illustrated in the plan view of <FIG>, it should be noted that the rows of hollow portions <NUM> of the sections <NUM> are mutually misaligned along the axial direction of the sections <NUM>. There is, therefore, a shift in position of the rows of hollow portions <NUM> between the sections <NUM> of the roller <NUM>. This position deviation of the hollow portions <NUM> may be achieved in the order of <NUM>-<NUM>, according to different configurations.

In the configuration shown in <FIG>, the position deviation is constant and progressive for a given number of sections <NUM>. For example, a succession of n sections <NUM> may have a progressive deviation of about <NUM>. In other words, from a first to a second section <NUM> there is a deviation of <NUM>, and from the second section <NUM> to the third section <NUM> there is a further deviation of <NUM>. At the end of a first succession of n sections <NUM> with constant and progressive deviation, a second succession of n sections <NUM> shows the same arrangement of hollow portions <NUM> as the previous succession. In this regard, by way of example, the Figure shows a reference line P configured for indicating the constant and progressive deviation of the hollow portions <NUM> for a succession of five sections with hollows <NUM>. In <FIG>, this constant and progressive deviation of the hollow portions <NUM>, which in this exemplifying case refers to a succession of five sections with grooves <NUM>, is to be understood as defined by the distance between the centers of the further reference lines parallel to the reference line P.

According to a further configuration not shown, considering a succession of n sections <NUM>, the deviation in position of the slots <NUM> between the sections <NUM> can be increasing from one section <NUM> to another (for example, from a first to a second section, deviation of <NUM>, and from the second section to a third section deviation of <NUM>).

Of course, the position deviation of the hollow portions <NUM> between the sections <NUM> may be achieved differently from what has been described above, provided that it is suitable for achieving the intended objects, i.e. creating the pre-incision effectively and limiting the wear of the cutting edges <NUM>.

<FIG> illustrates a schematic side view of a preferred embodiment of an apparatus according to the present invention. According to a further characteristic of the invention, the apparatus <NUM> is configured to carry out an automatic sorting of the packages C produced.

In one or more embodiments, the apparatus <NUM> has a plurality of conveyor means <NUM>, <NUM>, <NUM>, <NUM> configured for automatically transporting the strips of consecutive pre-engraved uncut packages C automatically towards respective evacuation points <NUM>, <NUM>, <NUM>. Preferably, the apparatus <NUM> has at least three evacuation points <NUM>, <NUM>, <NUM> of the strips of packages C by means of the automatic activation of vacuum areas, to automatically sort the packages C towards certain collection points. These vacuum areas are made by vacuum conveyors of known type.

The function of the conveyors <NUM>, <NUM>, <NUM>, <NUM> is to positively guide the strips of packages C towards the evacuation points <NUM>, <NUM>, <NUM> (for example, within a collection box accessible from the outside or onto a further belt to carry the packages C out of the overall dimensions of the apparatus <NUM>, for subsequent collection and bagging). The conveyors <NUM>, <NUM>, <NUM>, <NUM> may be alternatively activated, according to a predetermined cycle by means of a command signal sent by the control device E, to allow n strips of packages C of m products to be respectively transported towards a given evacuation point <NUM>, <NUM>, <NUM>.

The conveyor means <NUM>, <NUM>, <NUM>, <NUM> may comprise a plurality of lower belts <NUM>,<NUM>,<NUM>, and an upper belt <NUM> configured for gripping the package portions C between their respective mutually facing surfaces. The upper belt <NUM> has a length substantially corresponding to that of the lower belts <NUM>,<NUM>,<NUM> in succession. Each lower belt <NUM>,<NUM>,<NUM> is arranged to guide the strips of products towards a respective evacuation point <NUM>, <NUM>, <NUM>. As indicated above, the conveyors <NUM>, <NUM>, <NUM>, <NUM> may comprise preferably sub-atmospheric pressure gripping means comprising a source of sub-atmospheric pressure.

In one or more embodiments, such as in the one illustrated in <FIG>, the apparatus <NUM> comprises further transport means <NUM> arranged at the end of the line with respect to the evacuation points <NUM>, <NUM>, <NUM>, to transport the separate cut packages C beyond the aforesaid evacuation points <NUM>, <NUM>, <NUM> in an end-of-line point <NUM> for picking up (for example, for the bagging of packages of larger dimensions).

Thanks to these characteristics, the apparatus <NUM> is arranged to carry out a differentiated automatic sorting of both the individual separate packages C and the strips of pre-engraved packages C.

Claim 1:
A transversal cutting unit (<NUM>) for obtaining segments of consecutive articles of desired length, having engravings between one article and another of the same segment of consecutive articles, comprising:
- a cutting roller (<NUM>) carrying at least one cutting element (<NUM>) configured to perform both a cutting operation to separate two consecutive articles, and an engraving between two consecutive articles without separating the articles,
- a contrasting roller (<NUM>) acting as a cutting surface, wherein a plurality of sections with grooves (<NUM>) are formed alternating with a plurality of solid sections (<NUM>), configured for providing segments of consecutive articles of desired length, with engravings between one article and another,
- a control device (E) configured to vary the phase between said cutting roller (<NUM>) and said contrasting roller (<NUM>).