HRP20040640A2 - Heat-shrinkable film packaging for bottles, process for manufacturing said packaging and score cut equipment used in said process - Google Patents

Abstract

A packaging for bottles made with a heat-shrinkable film, of the type divisible into submultiples or with an easy-opening feature, in which the series of incisions provided in the film, to obtain its opening in the required zones, are performed with the score cut method. There are described series of incisions consisting of two or more lines of aligned incisions, parallel and close one another, which allow to obtain a better directionality and a reduced tearing energy. The invention also includes the manufacturing process of said packaging and the score cut equipment apt to perform said lines of incisions in the heat-shrinkable film. <IMAGE>

Description

The subject invention relates to packaging for bottles with heat-shrinkable film. With the word "packaging" here is indicated the well-known wrapping used to market any type of container - especially plastic bottles - achieved by wrapping a group of containers with a certain length of heat-shrinkable polyethylene film in such a way as to cause the overlap of two free strips of film on to the bottom of the container, after which a thermal procedure is applied in such a way as to achieve the thermal tightening of the film on the group of containers and the mutual hermetic joining of the two free strips along the length of the film. The number and arrangement of a group of tanks may vary depending on their shape and volume and depending on the material from which they are made; the arrangement that is most often used so far, for example for placing on the market mineral water and/or soft drinks in 1.5 or 2 liter bottles, is formed by a group of 6 bottles arranged in three parallel rows in two bottles each. In the following description and drawings, for the sake of simplicity and uniformity, only "bottle" type containers are referred to, which essentially represents the type of container that is more often packed in the above-mentioned packaging method; however, it is understood that the invention is not limited in any way to such particular application, but includes any type of container available on the market, whether made of paper, cardboard, plastic, metal, or any combination of these materials.

In particular, the invention refers to a package of this type that can be divided into several parts, each containing a smaller number of bottles while maintaining the integrity of the packaging to facilitate its removal. The characteristics and advantages of this type of container are well described in patent EP-B-717,712 of the same applicant, the contents of which are fully incorporated herein by reference.

The subject invention also relates to packaging for bottles made with a heat-shrinkable film, so-called easy-to-open, so that the packaging is made with means that enable easier tearing at predetermined places and thereby enable the extraction of one or more bottles from the packaging, without film for packaging.

The subject invention also includes a process for producing a heat-shrinkable film for packaging a group of bottles that are arranged next to each other in parallel rows, in a way where: the heat-shrinkable film is prepared by a series of aligned slits located on the middle part of the film area, which are compacted between adjacent rows of bottles; an even number of bottles are arranged in a group that includes several adjacent parallel rows; a length of said film is wrapped around said group of bottles to cause their free strips to overlap at the bottom of the group of bottles; a certain length of the film thus wrapped around a group of bottles is heated in a furnace with hot air so that thermal contraction of the film is caused around the bottles.

Finally, the invention relates to slitting equipment where a roll of film is processed with suitable tools to produce one or more slit lines on the film.

The above-mentioned patent EP-717,712 provided a new type of packaging for bottles using a packaging film where a large number of linear incisions, spaced at appropriate pitches, are made along the separation lines located between the two rows of bottles. This type of package is easily divided along the indicated score lines into subgroups of at least two bottles, so that each bottle of the subgroup remains firmly in place after separating part of the package. This new type of packaging - distinguished on the market by the trademark ZIPACK® - has solved a large number of problems related to the transport and marketing of bottles packed in heat-shrinkable plastic films, which are now widely used instead of previous forms of transport such as are wooden or plastic boxes with internal frames for separation. Among the major advantages provided by the ZIPACK® system - in addition to the fundamental advantage, which is the possibility of ordering and carrying a smaller number of bottles than what is characteristic of standard packaging, and which are tightly gripped and easy to transport, the following should be mentioned: speed and ease of separation subgrouping using only hands, elimination of any part or remainder of the packaging film at the point of sale, the possibility of choosing the size of subgroups in relation to the needs of the order and the carrying capacity of each individual consumer, and finally dissuading consumers from ordering only one bottle due to the fact that the smallest subgroup that contains two bottles much easier to carry than one bottle.

During the first period of application of the ZIPACK® system, some technical details and marketing requirements came to the fore, which, in fact, represent the subject of the essence of this invention.

In more detail, the first technical detail of ZIPACK® packaging, which in certain conditions would lead to the growth of problems, is the efficient direction of the film tear line, which is made by each individual notch, when separating the subgroup. In the known production processes, in fact, the cuts - which consist of linear cuts of length in mm - are made by rotary cutting devices for blades that penetrate the foil, shown in figures 1 to 3. A cutting disc T equipped around the circumference with serrations D for cutting (picture 1) is mounted, coaxially and nearby on one or preferably two bearing wheels R, R' (picture 2), on the foil P to be cut. The wheels R, R' have a slightly smaller diameter than the disc T to allow the teeth D to protrude a certain amount to cut the foil. The wheels R, R' guide and wind up unlike the roller C placed under the foil P, while the teeth D and the disc T pass through the foil P and enter the corresponding groove made on the roller C. Both wheels R, R' and the cutting disc T, which is located between them, and the roller C revolve at idle and are set in motion by the movement of the foil P, which revolves around a specially driven roll. The cutting line obtained by such a device is shown in Figure 3 and includes a series of cuts of length t that are repeated with a constant step L, so that an uncut length p = L – t remains, hereinafter simply referred to as "uncut", between the two following cuts . The cut/uncut ratio and pitch size L can be varied by modifying the dimensions and pitch of the teeth D on the disc T.

However, with this method of cutting, it is not possible to avoid, whenever the blade "enters" into, albeit with less effect, and exits the notch, that the blade slightly tears the foil and thereby makes two small opposite splits, so that the two ends of each linear notch have a Y- shape, the size of which mainly depends on the construction and operational characteristics of the cutting equipment, on the quality of the blades and on the level of their maintenance. When, for example, due to either inadequate mounting or excessive insertion of the knife - the size of the specified Y-shaped splits becomes apparent, after the film clamping phase, the shape of the notch, instead of the desired buttonhole shape with sharp ends, will have a rounded rectangular shape characterized by a reduced possibility of providing a correct towards the tear line when separating packaging subgroups. In these cases, the tear of the packaging film would not be completely regular so that the tear line could deviate in one or more zones - especially those where the packaging has a stronger curvature - from the scoring line performed on the film. Tearing of this type is not satisfactory, not only from the point of view of aesthetics, but because it could require more energy when tearing, and could sometimes determine unsatisfactory holding of bottles that are in a separate subgroup.

Therefore, the first objective of the present invention is to provide a package - and a corresponding production process - in which the film scoring lines show such a structure that ensures a perfectly regular separation of the package into subgroups, which means extremely easy separation, precisely performed along the film score line, and in addition perfect mechanical resistance of the packaging during its transport.

Another technical problem considered by the applicant is the achievement of easy and clean separation of package subgroups even when the bottom of the package, i.e. where two free strips along the length of the packaging film are overlapped and tightly joined to each other. The fact is that the adjustment of two overlapped free strips is never perfect, and sometimes it can happen that the notches of one of the free strips actually overlap the uncut area of the other free strip, so that it is partially sealed during the shrinking phase, which makes the separation of the packing subgroup less fast and efficient.

The greater finesse of the wrapping techniques to wrap the length of the film around the group of packaging bottles has enabled the improvement of the abutment of the two free strips and as a result the overlapping of the corresponding scoring lines, thus significantly reducing the size of such a problem which, nevertheless, cannot be fully solved in this way. eliminate.

In patent IT-1,289,944 of the same applicant, an inventive packaging process is proposed, which solves this problem by maintaining or establishing a notch of at least two overlapping free strips along the length of the film in the open state. Especially the first procedure ensures the adjustment of the temperature of the film in the lower part of the package, along the lines of the nicks, by placing the protective frames in the heat shrinking oven, in order to reduce or cool the air flow in relation to the above area, and to avoid closing the nicks as a consequence. In the second procedure, an open state of the notch was established in the lower part of the package, after exiting the heat-shrinking furnace, using appropriate cutting tools that are applied to the finished package. In a third process, the score lines on one of said two free strips consist of two wide button-shaped holes large enough to completely overlap the normal score lines located on the other free strip, in order to avoid their hermetic closure. In the fourth, later process, one strip of film is subjected to a circular treatment along each scoring line in order to reduce its surface reactivity and prevent the subsequent hermetic closure of the free strips in relation to said strips and thus achieve an open state of scoring.

Another type of solution to this problem is suggested in patent EP-868,364, according to which, in connection with each scoring line, a strip of film coated with printing ink is provided to give said strip the characteristic of not being hermetically sealed. This technique makes it possible to avoid the hermetic joining of two overlapped free strips of film in relation to the scoring lines and in the vicinity of them, so that the open state of the score is maintained even in the presence of adjustment errors when overlapping the two free strips.

Both of the above-mentioned patents allow a definitive solution to the problem described above, even if the price of introducing some variations in the process or an additional working stage of the film imposes unwanted additional costs in the packaging production process.

Therefore, another object of the present invention is to provide a new type of packaging - and a corresponding packaging method - in which the separation of the subgroup takes place in a fast and clean way along the perimeter of the package, including its lower part, without any need to modify the existing method of manufacturing the package or perform additional treatment on the film except for the provision of scoring lines.

In addition to the technical improvements mentioned above, the commercial experience with the ZIPACK® system so far has established the need to also enable - at least for some conservative segments of the market - an easy package opening system, which enables easy and quick lifting of one or more free bottles from the package. The easy opening systems of the known techniques offered up to now are not satisfactory enough from both a practical and an economic point of view in order to reach the right and wide spread on the market. The often present defects in such known systems are relative to the fact that the easy opening characteristic is achieved either by using additional materials along the opening lines on the package (such as threads, tapes, etc.), or with some special additives integrated in the normal components of the film for packaging (such as polymeric materials with high tear direction, etc.), whereby the materials generate in both cases an increase in the overall cost of packaging. Moreover, these known systems are not always practical when opening and sometimes present a drawback when generating strips or film tear residues that create clutter and less attractive points of sale, and require additional time to remove them.

The third objective of this invention is to provide a package with the characteristic of easy opening. and an appropriate production method - which does not require the use of any additive or special material, in addition to the heat-shrinkable film that is commonly used for the production of traditional packaging, and which, moreover, does not raise film strips or residues during the opening process.

The fourth objective of this invention is finally to provide cutting equipment intended for performing scoring lines on a heat-shrinkable plastic film, and to be successfully used in the production processes for bottle packaging according to the subject invention.

These objectives are all achieved, according to the present invention, by the packaging with the characteristics defined in independent patent claims 1 or 5, the production method with the characteristics specified in independent claims 10 or 14, and by means of the cutting equipment with the characteristics defined in independent claims 17, 19, 21 , 23 or 24. Other features of the invention are defined in secondary dependent claims.

Further characteristics and advantages of packaging, manufacturing methods and cutting equipment according to the present invention will become more clear from the following detailed description of some preferred embodiments of the packaging and cutting device invention, which are illustrated in the accompanying drawings, wherein:

Fig. 1 is a front view of a penetration cutting device according to the prior art, which can be used to perform scoring lines on a ZIPACK® package;

Fig. 2 is a side view, partially in section, of the cutting device of Fig. 1;

Fig. 3 is a drawing illustrating a scoring line drawn along the length of the film, using the cutting device shown in Figs. 1 and 2;

Fig. 4 is a front view of a cutting device according to the state of the art;

Fig. 5 is a side view, partially in section, of the cutting device of Fig. 4;

Fig. 6 is a drawing illustrating a scoring line made on film, by means of the cutting device shown in Figs. 4 and 5;

Fig. 7 is a front view of a notching device with supporting teeth, which can be used to perform notching lines on a package according to the present invention;

Fig. 8 is a side view, partially in section, of the cutting device of Fig. 7;

Fig. 9 is a front view of a slitting device with elastic wheels, which can be used to perform slitting lines on a package according to the present invention;

Fig. 10 is a side view, partially in section, of the cutting device of Fig. 9;

Fig. 11 is a side view, partially in cross-section, of a cutting device equipped with an elastic support wheel of variable diameter, which can be used to perform cut lines on a package according to the present invention;

Fig. 12 is a side view, partially in section, of the device from Fig. 11 in a different working position;

Fig. 13 is a plan view showing a scoring line made on the film, by means of the cutting device shown in Figs. 7 to 12;

Fig. 14 is a front view of a slicing device having a plurality of slicing discs, which can be used to perform scoring lines on a package according to the present invention;

Fig. 15 is a side view, partially in section, of the cutting device of Fig. 14;

Fig. 16 is a plan view showing a scoring line made on the film, by means of the cutting device shown in Figs. 14 to 15;

Fig. 17 shows a schematic perspective view of a package that can be divided into separate sections, according to the present invention;

Fig. 18 shows a schematic view of the package in perspective with the characteristic of easy opening, according to the subject invention;

Fig. 19 shows a schematic front view of the cutting equipment according to the present invention; and

Fig. 20 is a side view of the cutting equipment from Fig. 19.

After carefully studying the system of the film cutting mechanism as well as the heat shrinking mechanism of the packaging, the applicant successfully found the defects - shown in the previous part of this description - belonging to the traditional cutting devices used to perform scoring lines on the film used for production ZIPACK® packages, i.e. penetration cutting devices.

For this reason, the applicant conducted market research, even in market areas distant from the market of the subject invention, to determine the availability of other cutting methods that do not have the above-mentioned disadvantages. During the research between the different cutting methods tested, the notch cutting method is the one that shows really better cutting characteristics, at least at the potential level. A cutting device of this type is shown schematically in Figures 4 to 6.

Also in this case, the cutting tool consists of a disc T that directly rests on the opposite roller C, and with its teeth D the inserted film P is cut. With the purpose of ensuring constant contact with the opposite roller C, in this case the outer profile of the teeth D is perfectly circular with an edge that is not particularly sharpened, so as not to carve the surface of such opposite roller C. The cutting disc T is mounted on a mobile holder S which is pneumatically operated so that the disc T exerts a predetermined constant pressure on the opposite roller C.

Apart from simple compression along the cutting line, since there is no relative movement between the film P and the teeth D, this type of notching device performs high-quality cuts; in this way, it is not possible to create short splits or side tears, which are typical when performing the penetration cutting method. Conventionally, slotting cutters have been used to make continuous cuts using a T disc having one perfectly circular edge; their application was further extended to obtain the type of notch lines shown in Figure 6, where the notch/unnotched ratio is extremely large. In order to achieve such a result, short breaks or gaps are made on the outer line of the disk T with a continuous edge, in order to determine the formation of teeth D with a circular profile on that disk. As the width of these gaps must be very small, the fact that the cutting disc T is in continuous contact and exerts pressure on the roller C must be taken into account, so that if the gap between the two following teeth D were too large, the sudden approach of the disc T to the roller C should unfold in relation to the space between the two teeth, and that the next tooth will run into the roller C, which would result in an unacceptable impact and a sudden displacement of the disc T and thus create an unacceptable impact of the disc T. In part, in order to to keep the impact at a low enough level to avoid rapid destruction of the teeth D, for standard discs with a diameter of 100 mm it is necessary that the space between two adjacent teeth is not greater than 1 mm. Proportionally larger gaps can be used with cutting discs that have a larger diameter.

Taking all this into account, it seems quite clear that slitting machines of the known type are completely unsuitable for performing slitting lines on the film used for ZIPACK® packaging, in view of the fact that on such a film the slitting lines must have an "unscorched" portion of the scoring line is wide enough, in order to ensure the necessary stability of the package during heat sealing and transport operations, and therefore in a normal package containing 6 bottles of 1.2 - 2 liters, it is at least 4 - 8 mm.

Recently, a new type of holder S for the cutting disc T of the grooving cutting device was developed, in which, in addition to the constant cutting pressure, an adjustable longitudinal stroke of the disc was made possible. In fact, such a stroke is not only limited, as in previous designs, to 2-3 mm at maximum drive, but is finely adjustable by means of micrometric regulation, in order to allow the disc to drive only the necessary stroke to penetrate the entire film, and cutting it, and thus without allowing any further penetration of the cutting disc into the interspace between two adjacent teeth and thus without the occurrence of the above-mentioned problems, i.e. striking the disc T against said interspaces.

However, none of these technical devices is suitable for solving the problem, considering the fact that both the cutting disc T and the opposite roller C rotate in a connected manner (devices with a mechanical connection between the disc T and the roller C, as well as the powered versions are in fact as a rule they do not use due to the higher cost and complication of the device ) so that their rotation is ensured only by the movement of the film P, it is quite clear that in the case of contact between the disc T and the roller C should be regularly and repetitively lost in relation to each intermediate space between adjacent teeth, where were such a gap to be wide enough to generate a score line with the desired uncut length, the drive on the cutting disc could become extremely erratic resulting in unacceptable unevenness in the formation of the score lines.

Faced with these problems, the applicant nevertheless took advantage of the positive technical performance of the slitting cutting system and invented a slitting device that enables slitting film that performs slitting lines with a cut/uncut ratio whose value can be adjusted as desired without causing problems related to to hitting the disk T on the opposite roller C. The present invention was obtained on the basis of such a device.

The first way of performing such a cutting device is shown in Figures 7 and 8. As shown in Figure 7, the cutting disc 1 – suitable for cutting by notching, but with rather wide spaces between its teeth 2, and suitable for performing notching lines for ZIPACK ® packing – is equipped with a toothed disk 3 of the same diameter and in rotation coaxially and firmly connected to it. The protrusions 4 of the toothed disc 3 are located exactly in relation to the spaces between the teeth 2 of the cutting disc 1 (as shown in Figure 7 where only a few teeth are shown for simplicity) and the minimum extension of each tooth is equal to the extension of the corresponding space minus the maximum value of the circumferential an intermediate space equal to 2/100 of the toothed disk diameter. The teeth 4 have a sufficiently wide thickness to guarantee a good bearing between two adjacent teeth (as clearly shown in figure 1), however without determining any deterioration in the film P on which they rest; for this purpose they preferably have suitably smoothed edges. In this way, the cutting tool, which consists of a set of discs 1 and 3, during its rotation rests on the opposite roller C alternatively with one tooth 2 of disc 1 or with one protrusion 4 of disc 3, while a slight transition from the first to the second is desirable guaranteed by the above-mentioned circumferential tolerance, equal to 1/100 of the toothed disk diameter, between the end of one tooth 2 and the beginning of the projection 4 and vice versa. It should be clearly understood that while the specified tolerance cannot have a value greater than that specified for the purpose of avoiding striking the cutting tool, such tolerance may be lower, zero or have a negative value (ie the circumferential extension of the protrusion 4 may be greater than the corresponding disc clearances 1 ) without significantly jeopardizing the functionality of the cutting tool, however, at the moment such a solution is not desirable. The second toothed disc 3' (only its outer line is indicated in Figure 8) can be placed on the outer side of the disc 1, in case it is desired to obtain a perfectly symmetrical construction of the cutting tool.

Therefore, with this solution, it is possible to shape the teeth 2 of the cutting disc 1 at any desired distance, and especially at the specific distance required to perform scoring lines suitable for performing ZIPACK® packaging films, while completely avoiding any hitting the cutting disc against the opposite roller. In fact, in the case where none of the teeth 2 is in contact with the opposite roller C, the desired stability of the cutting tool, which means the essential lack of any movement in the direction of arrow F in Figure 8, is ensured by the presence of the protrusions 4 that abut the opposite roller C .

Therefore, with the device described above, it is possible to produce films P made with scoring lines that have the desired score/unscored ratio, such as the film shown in Figure 13, fully suitable for the production of ZIPACK® packaging as shown schematically in Figure 17. Thanks in the notch cutting process, the notch lines obtained are completely without any defects, which were found in the notch lines produced by known penetrating cutting devices, so that they provide a good tear direction and fully achieve the first objective of the invention.

A version of this method of execution that also enables an additional technical function is shown in Figures 9 and 10. In this case, the cutting disc 1 is coaxial and rigidly connected in rotation to the bearing wheel 5. The bearing wheel 5 consists of a metal hard core 6 whose outer edge equipped with a suitable elastic layer 7 which is made of elastomeric material. In the unstressed state, the outer diameter of the bearing wheels 5 is equal to or slightly larger than the diameter of the cutting disc 1, in relation to the degree of elasticity of the elastomeric layer 7, in such a way that when the disc holder 1 (not shown) is pressed to the working pressure against the opposite roller C , the layer 7 of the supporting wheels 5 loosens enough to allow the cutting disc and especially the teeth 2 to pass through the foil P to be cut.

This simple solution makes it possible to completely avoid the phenomenon of hitting, and therefore allows the teeth 2 of the disc 1 to be shaped at a distance that is adequate to perform the scoring lines necessary to prepare the film for the ZIPACK® packaging. In fact, when there is no direct support of the teeth 2 on the opposite roller C, the desired stability of the system, i.e. the lack of visible movements in the direction indicated by the arrow G in Figure 10, is ensured by the elastomeric layer 7 of the wheel 5 which will react elastically to the greater load determined by the absence of teeth and - thanks to the correct choice of the relative coefficient of elasticity - it can succeed in avoiding any sensitive descent of the cutting disc 1, in the space between two adjacent teeth 2, and as a result any impact phenomenon is avoided. In the pictures, only one bearing wheel 5 is shown, but it is clear that with obvious modifications of the cutting tool it will be possible to provide a second bearing wheel 5' (shown in Figure 10 by a dashed line) which is placed symmetrically on the other side of the cutting disc 1, whereby would ensure more useful or efficient operation of the same device.

In addition to the above-mentioned fundamental function of supporting the cutting disc within the space between two adjacent teeth, the bearing wheel 5 described above also achieves another very important function, which is to ensure the correct and continuous operation of the cutting device and therefore the cutting disc 1, and thanks to the movement of the film P with which the supporting wheel 5 maintains continuous contact. Such an additional function retains its importance also in the case where the end stroke of the cutting disc is controlled - in a much more expensive way - by means of a micrometric stop regulation in such a way as to mechanically prevent the extended longitudinal movement of the cutting disc 1 beyond the value required to cut the film P In fact, even in this case, the support wheel 5 is essential to maintain continuity of contact with the film P between two adjacent teeth of the disc 1 to avoid possible mutual sliding between the film P and the cutting tool, which would negatively affect the position and quality of the cut.

The second version of the first embodiment of the invention is shown in Figures 11 and 12 and provides, in addition to the above advantages of the first version, another additional advantage. According to this version, the bearing wheel 5 consists of a metal core 6 that has a cavity around the circumference on which an elastomeric seal 17 is placed in the form of a ring and is hollow in the middle, which provides the cutting tool with the same continuous load-bearing function that the elastomeric layer 7 provides in the first version. In this second version, the cutting device enables - as already foreseen - another additional function, thanks to the fact that the metal core 6 of the wheel 5, and due to the elastomer seal 17, can, due to the action of the electromagnet 9 which is located around the mobile core 8, occupy two different positions shown in Figures 11 and 12, to slide longitudinally relative to the supporting shaft (not shown) of the cutting device. When the electromagnet 9 is activated, the core 8 moves from position d (Fig. 11) to position d' (Fig. 12) and moves to the left side of the drawing and, through the bell-shaped clamp 10 is firmly connected to it, determines the corresponding movement of the outer wing of the core 6 in order to reduce the internal volume of the cavity holding the seal 17. Accordingly, said seal is suitably flattened and there will be a reduction in the volume of its internal cavity as well as an increase in its diameter, and in order to determine the lift z of the cutting device sufficient to allow similarly lifting the cutting disc 1 from the film P and thus interrupting the scoring line. The above-mentioned electromagnetic control is characterized by both high execution speed and low inertia, and is therefore perfectly suitable for performing cyclic interruptions of scoring lines even at high operating speed, which is necessary in one of the methods of performing packaging according to the invention in question, which will be described below.

Apparently, according to the two versions described above, the bearing wheels, which have a circumferential edge made of elastomeric material, can also be used in connection with the toothed disk of the first embodiment of the present invention. In fact, such a connection will make it possible to achieve a very good driving effect on the film and take advantage of the interesting possibilities of spatial cutting made possible by a carrier wheel with a variable diameter, while maintaining the precision of mechanical setting that is typical of a toothed disc.

Another embodiment of the cutting device according to the present invention is shown in Figures 14 and 15 and was studied by the applicant with the aim of providing scoring lines characterized by high directivity as well as low tearing energy. In this second embodiment of the invention, the cutting tool consists of two cutting discs 1 and 1' which are attached to the same shaft and firmly connected to each other, whereby one or two bearing wheels 5 may or may not be used on the side, the same as shown for the two versions in the first embodiment of the invention. For the sake of simplicity, only one version without load-bearing wheels is shown in the pictures. The distance i (Figure 16) between the two discs 1 and 1' is usually about a few mm, more precisely it is contained between a minimum value of about 1 mm and a maximum value approximately equal to the length of the uncut part p located between two adjacent notches on the same cutting line , preferably such a distance is contained in the range of 2-3 mm.

As shown in Figure 4, discs 1 and 1' have the same number of teeth 2 and 2' with identical pitch and which are mutually mounted in such a way that the teeth of one of the two discs have a configuration that perfectly alternates with that of the adjacent disc . In the context of the second embodiment of the invention, Figure 16 shows a certain cutting line obtained by the above-described cutting disc. In the method of carrying out the invention shown above and with regard to discs of a standard type having a diameter of about 100 mm, the maximum amount of steps L teeth 2, 2' is 2 mm longer than the cutting length t teeth so that during the rotation of the cutting tool between one tooth and the next on an adjacent disc, there will be no interval s longer than about 1/100 of the diameter of the cutting disc, i.e. 1 mm in the case of standard 100 mm diameter cutting discs. Under this condition, the teeth 2, 2' can have, for example, a length of 4 mm and a step length of up to 10 mm. In this case, there will be no impact of the cutting tool on the opposite roller C, considering that the carrying capacity of the tool is provided alternately by one tooth 2 of disc 1 and one tooth 2' of disc 1', and therefore the cutting tool can be used as it is and has a clear advantage due to the simplicity of the system.

On the other hand, in the case when the space between the two following teeth 2 and 2' (of the two adjacent discs 1 and 1') has a length greater than the above, it is necessary to fix the cutting tool with at least one toothed disc 3 and/or at least one supporting disc 5 of the type shown above, which are suitable for supporting the cutting tool which is also attached to the space between two subsequent teeth regardless of the length of the space.

As previously stated, such a cutting tool was studied with the aim of achieving scoring lines for ZIPACK® packaging that provide better characteristics such as high directivity and reduced tearing energy. In fact, by applying such a cutting line to the P film used for the production of ZIPACK® packaging, the applicant obtained real confirmation that the said cutting line truly provides an absolutely superior performance both from the point of view of the high directionality of the film tear and from the point of view of the reduced energy required to tear the film, so that this operation is much easier to perform on the part of the user. In addition to this, a package formed using nick lines of this type proves to be much more stable during the heat shrinking process as well as during transport, since the tensions on the film P are divided between twice the number of nicks and as a consequence the stress on each individual nick is significantly reduced. Finally, surprisingly enough, the package produced by the above notch line provides complete separation of the package subgroup, even in the bottom region of the package - where, in relation to what was said in the introduction, the most critical conditions are found - without necessarily applying any special procedure to film P or to modify in any way the process for the production of packaging.

The explanation for such a particularly positive performance probably lies in the fact that with a traditional scoring line it is necessary, during the transition from one notch to the next during the tearing operation, to tear a part of the film that is quite long (4-8 mm) in a well-established direction, i.e. incision lines. In contrast, by using a certain double nick line as in the second embodiment of the invention, the tear of the film can take place either along the above-mentioned direction of the nick line or even along an oblique direction, i.e. to progress from one nick on the first nick line to one located laterally on to the adjacent score line, increasing the overall probability that the score line opens in the direction of the intended direction, and it is actually quite improbable that the tear line starting from the predetermined score continues in a transverse direction that is opposite to that where the next side-adjacent score is located, at the moment when the tearing action reaches a certain notch, considering that the film already shows considerable weakening towards the next notch on the side which is already beginning to deform. Since this phenomenon will occur alternately on two adjacent scoring lines, it is more likely that the tear pattern - in fact the one that requires minimum opening energy - will have a typical "slalom" pattern configuration.

In addition, taking into account that the energy required for "lateral tearing" - i.e. that which takes place between a certain notch and the next notch on the side - is on average lower than the energy required for "longitudinal tearing" - i.e. that which takes place between a certain notch and the next one on the same line - due to the fact that the length of the tear film is shorter (about 2-3 mm compared to 4-8 mm), and with this new type of notch line, an overall energy reduction is also achieved which is needed to separate the two packaging subgroups.

Finally, even in relation to the positive characteristics that allow a high-quality complete and easy separation of the packaging into subgroups - independent of any possible sealing of the notch that may have occurred between two free strips of packaging - it can be assumed that this may depend on the fact that possible zig zag the progression of the score line as the tearing continues is such as to allow the pre-opening of the scores which may have been sealed during the heat shrinking of the package.

However, the actual mechanism of action that takes place during the tearing of the film - whereby the above explanations are considered only as a mere explanatory hypothesis, and has no limiting value on the scope of the invention - has been tested in a large number of experiments and production tests that were carried out under very different heat shrink conditions packages and proved that the special double notch line obtained with the cutting device from the second embodiment of the invention allows obtaining: a better distribution of stress along the different notches during the heat-shrinking phase and as a consequence less rounding of them, while all of this makes it possible in a very safe way to avoid any accidental opening of the packaging either during production or transport; a very good direction of the tear line and a lower amount of energy required to perform the tear operation and to ensure the first object of the invention even with better performance compared to the first method of carrying out the invention shown above; perfect and easy division of the package into subgroups, also in the lower zone of the package, without the necessity of applying a preventive treatment to the film and without any modification of the production process, thus achieving the second goal of the subject invention.

In the embodiment of the invention shown above, only two cutting discs 1 and 1' are provided. However, the applicant has conducted cutting experiments and package manufacturing tests with a larger number of cutting discs, for example 3 or more adjacent discs, each positioned with teeth arranged in a zigzag fashion with respect to the adjacent disc. With this type of cutting tool, special scoring lines are obtained, which, after the heat-setting phase is completed, have a typical honeycomb configuration, and show a very high mechanical resistance and, at the same time, a very important ease of tearing to be useful for specific applications. An appropriate application of this type of scoring line is, for example, the one used for packages with the characteristic of easy opening, and due to the greater width of the tearing area, and the accessibility of the package to actually take out the bottles much easier.

In addition, the package with the characteristic of easy opening can also be realized according to the third embodiment of the present invention, which foresees a cutting device consisting only of two mutually connected cutting discs located at a distance that is much greater than that considered in the second embodiment of the invention, for example 2-3 cm, thus creating two incision lines that are far enough apart that they are independent and do not affect each other. Also, this cutting tool, like that described in relation to another embodiment of the invention, may or may not be connected to one or two supporting wheels having an outer rim made of an elastomeric material to ensure proper and continuous support of the cutting tool in in the event that the support provided by the cutting discs should not be sufficient due to the specific cut/uncut ratio of the same discs. Preferably in this case there will be only one supporting wheel, located between the two cutting discs to also become useful as their spacing element. In addition, the two scoring lines could also be of the type obtained with both cutting devices described above, so that they are either single or double lines, which in the latter case have - even in this type of application - the same additional advantages already established before and described above.

In the final produced packaging with the film made with the cutting device according to the third embodiment, the scoring lines are no longer located in the middle zone between two adjacent rows of bottles, but on the contrary closer to the necks of the same bottles as shown in Figure 18. Therefore, on that way, it is possible, after the package is opened with respect to the indicated lines, to remove the freed bottles from the package with much more ease.

In this type of packaging application with an easy opening characteristic, it is often desirable to limit the scoring lines on the upper zone of the package to avoid accidental separation of the package into submultiples, which in this case is not welcome, or separation of film strips from the package, in order to achieve the third object of the invention . The arrangement of these partial scoring lines is shown in Figure 18, with regard to the embodiment of the invention with two spaced scoring lines.

Periodic interruption of the scoring lines can be achieved either by temporarily separating the cutting discs from the film P during the film cutting operation, or by using a cutting disc having a larger diameter than that previously described, the outer circumference of which will have a length identical to the length of the film being cut. used for packaging production. In both cases, during the packaging process, it will then be necessary - to use a procedure well known and applied for advertising synchronized listing - to synchronize the cutting operations along the length of the film to ensure that the part of the film with the cuts will be placed in the required area.

In this first case, due to the high speed of the film advance during the operation of cutting the scoring lines on the same film (typically 2-3 m/s), the periodic separation of the cutting tool from the film should be achieved with devices of low inertia in order to achieve a sufficiently fast intervention time . The first alternative is to use the same pneumatic device that maintains the pressure of the cutting tool on the film P using, for example, a double-acting piston to achieve rapid raising and lowering of the cutting tool and together with a suitable control system to activate the movement of the piston in relation to the film advance speed (often variable). Such a result can be achieved according to the present invention with a very simple and compact construction that provides for equipping the cutting tool with the least load-bearing wheel having a variable diameter, of the type shown in Figures 11 and 12 and as described above, in order to achieve repetitive lifting and lowering the cutting disc with the required speed and low inertia, which is necessary to achieve the desired frequency of intervention, and the advantage is the great simplicity of the device.

In the second solution, taking into account that the required usual film length - for a standard package containing 6 bottles of 1.5 or 2 liters capacity - varies between 105 and 110 cm, the cutting discs will therefore have a diameter between 335 and 350 mm, so that their outer circumference will be exactly the same as the length of the film. By using these discs and placing the teeth in one part of the same discs and after carefully centering the film before starting the cutting operation, it will be possible to cut the film only in the required zone.

However, the positive characteristics of the above-described third embodiment of the invention are not limited to the form in which the scoring lines are extended only to part of the package. In fact, it is also possible to extend the scoring lines over the entire package and deliberately move them in a vertical direction, and in order to ensure complete sealing of the lower part of the package and as a consequence to avoid continuing to separate the film all along the scoring lines, two overlapped free strips of film length P determine the complete separation of packing subgroups. Alternatively, it is possible to provide two series of cuts in a suitable zigzag fashion - by using two cutting discs with teeth that are arranged only in given parts along their circumference and by placing said discs towards each other in such a way that their parts with teeth will mutually result in a zigzag even - so that in the lower part of the package, the two free strips will be sealed due to the lack of overlap between the series of notches made on the free strips, while the characteristic of easy opening will be used satisfactorily by using alternatively one or the other of the two series of notches.

The different types of cutting devices described with respect to the various embodiments of the present invention are preferably incorporated into a free-standing cutting equipment as shown in Figures 19 and 20. Such a unit is fully autonomous and enables the preparation of a winch for pre-cutting the film P used in packaging machines of any known type in order to allow a very high flexibility in the application of the subject invention even in the case of existing plants. There is apparently nothing to prevent such a device, with the necessary modifications, being installed on the line of a specially designed packaging machine to perform scoring lines while unwinding the still unscored film, before the film is cross-cut to generate a length of film for packaging production.

In the unit shown in Figures 19 and 20, in order to enable the feeding of a double path of the packaging machine, the film P is of double width, the film P being split longitudinally in relation to its centreline. In the case of a standard pack of 6 bottles each, the number of scoring lines performed on the film is two for each pack, and for double the film size P is a total of 4. Therefore, the unit is equipped with four cutting devices D, which are customarily positioned on a common longitudinal bar, as shown in Fig. 19. The support bar of the device D is fixed while each cutting device is driven by the action of a suitable pneumatic pressure device (not shown) in a direction perpendicular to the support bar and to the opposite roller C which is located under the bar.

The film P is unwound from the feed winch A and wound onto the receiving winch B, after passing through a series of rollers M including, where necessary, two oscillating rollers N and finally arriving at the opposite roller C. The opposite roller C, as already detailed, is in contact with the cutting devices D and especially with their cutting discs 1. In order to perform the cuts, after its drive shaft has been properly started, the winch B is put into rotation, whereby, due to the simplicity of the motorization, the system is not provided speed control, so that film rewinding takes place at a constant angular speed and therefore at a linear speed that increases as the diameter of the winch B increases. Thanks to the different types of cutting devices shown, ensuring continuous contact between the film P in motion and the cutting tool - whether the latter includes a toothed disk 3 or a bearing wheel 5 - it is possible to avoid any mutual sliding between the film P and the cutting tool, and therefore, cutting with a characteristic of high correctness is achieved. Where necessary, it is possible to construct equipment for constant speed cutting, which, however, would obviously be much more sophisticated and expensive in that case. Such a result can be achieved, for example, by using winch B for rewinding, motorization which is equipped with a speed control system which is controlled by a film speed measuring system connected to roller C. Alternatively, it is possible to insert along the film path - preferably only after opposite roller C – a pair of rollers driven by a constant speed motor and that the winch motor B is equipped with a converter that electronically adjusts its speed of rotation to ensure controlled rewinding of the cut film.

The subject invention is described with reference to preferred embodiments of the cutting and packaging device, as well as with regard to the relevant manufacturing process. It is clear, however, that the scope of the invention is not limited by these ways of carrying out the invention, but includes all possible variants that the expert in the field can reach and all within the scope of the definitions given in the patent claims.

Claims (26)

1. Packaging with heat-shrinkable film, which is divided into subgroups, groups of bottles that are placed along each other in parallel rows, of the type in which a length of said film is wrapped around said group of bottles in order to derive a zone of overlap of its free strips with respect to the zone bottom of a group of bottles, whereby a series of notches is made on the film with respect to the planes that separate adjacent rows of bottles, indicated by the fact that said series of notches consist of two or more aligned notches, parallel and close to each other. 2. Packaging with a heat-shrinkable film according to claim 1, indicated by the fact that the immediately adjacent notches of one of the specified lines of the notches change in position in relation to the notches of the other of the specified lines. 3. Packaging with heat-shrinkable film according to claim 2, characterized in that the distance between said scoring lines is included between a minimum value of 1 mm and a maximum value equal to the uncut length of one of the scoring lines, and preferably between 2 and 3 mm. 4. Packaging with heat-shrinkable film according to claim 3, indicated by the fact that the number of specified lines is 2. 5. Packaging with heat-shrinkable film, defined with the characteristic of easy opening, of groups of bottles which are arranged along each other in parallel rows, of the type in which a length of said film is wrapped around said group of bottles so as to form an overlap zone from its free strips in relation to the zone bottom of a group of bottles, indicated by the fact that in relation to the zones of the film that is included between adjacent rows of bottles and on the opposite sides in relation to the planes that separate said rows of bottles, two rows of cuts are made, whereby said cuts are parallel and offset from said plane and extend to at least the upper part of the package. 6. Packaging with a heat-shrinkable film according to claim 5, characterized in that said strings have a mutual distance contained between 1 and 3 cm. 7. Packaging with a heat-shrinkable film according to claim 6, characterized in that said series of cuts extend for the entire length of the film and contain zones without cuts, alternatively located along it. 8. Packaging with a heat-shrinkable film according to claim 6, characterized by the fact that each of the indicated series of incisions consists of one or more lines of arranged incisions, which are parallel and close to each other, whereby the immediately adjacent incisions of one of the indicated incision lines are changed into position with regard to the incisions of the second of the indicated incision lines. 9. Packaging with heat-shrinkable film according to claim 8, characterized in that the distance between said scoring lines is contained between a minimum value of 1 mm and a maximum value equal to the uncut length of one of the scoring lines, and preferably between 2 and 3 mm. 10. Process for the production of packaging with heat-shrinkable film, which is divided into subgroups, groups of bottles that are placed along each other in parallel rows, of the type that contains the following steps: performing on said film a series of incisions relative to the central part of the film zones which are contained between adjacent rows of bottles; arranging an even number of bottles in a group consisting of two or more parallel rows; wrapping a length of said film around said group of bottles so that the overlapping zone of the free strips of film is positioned relative to the zone of the bottom of the group of bottles; thermally heating said length of film wrapped around a group of bottles to determine the heat shrinking of the film, indicated that is each of the series of arranged incisions according to step a) performed on the film along two or more lines, which are parallel and close to each other. 11. The method for the production of packaging with a heat-shrinkable film according to claim 10, characterized in that the notches of one of the mentioned lines of notches are alternated in the position immediately in relation to the nearby notches of the other of the mentioned lines. 12. A method for the production of heat-shrinkable film packaging according to claim 11, characterized in that the distance between said notch lines is contained between a minimum value of 1 mm and a maximum value equal to the uncut length of one of the notch lines, preferably between 2 and 3 mm. 13. Process for the production of packaging with heat-shrinkable film according to claim 12, characterized in that the number of said lines is 2. 14. Process for the production of packaging with heat-shrinkable film, determined with the characteristic of easy opening, of groups of bottles that are arranged along each other in parallel rows, of the type that contains the following steps: arranging an even number of bottles in a group consisting of two or more parallel rows; wrapping a length of said film around said group of bottles so that the overlapping zone of the free strips of film is positioned relative to the zone of the bottom of the group of bottles; thermally heating said length of film wrapped around a group of bottles to determine the thermal contraction of the film, characterized in that prior to step a) includes the following steps: performing on said film two series of notches in relation to the zones of the film located between adjacent rows of bottles and on opposite sides in relation to the planes that separate said rows of bottles, wherein said notches are parallel and offset from said planes, and extending said rows of cuts to a zone of each length of the film at least relative to the upper area of the package. 15. The method for the production of packaging with heat-shrinkable film according to claim 14, characterized in that each of the indicated lines of incisions consists of two or more lines of arranged incisions that are parallel and close to each other, whereby the incisions of one of the indicated lines of incisions alternate in position directly in relation to the nearby notches of the second of the mentioned lines. 16. A method for producing packaging with a heat-shrinkable film according to claim 15, characterized in that the distance between said score lines is contained between a minimum value of 1 mm and a maximum value equal to the unscored length of one of the score lines, preferably between 2 and 3 mm. 17. Equipment for slitting flat material, for performing a line with arranged slits with freely predetermined spacing, of the type where the flat material passes between an opposite roller and a cutting disc having an interrupted cutting edge, characterized in that said disc for cutting associated with at least one coaxial toothed disc, wherein said teeth are located relative to said breaks in the cutting disc. 18. Grooving cutting equipment according to claim 17, characterized in that the teeth have a circumferential extension which is not shorter than the circumferential extension of the corresponding breaks which are reduced by a maximum value equal to 2/100 of the diameter of the cutting disc. 19. Equipment for slitting flat material, for performing a line with arranged slits with freely predetermined spacing, of the type in which the flat material passes between an opposite roller and a cutting disc having an interrupted cutting edge, characterized in that said disc for cutting associated with at least one coaxial supporting and driving wheel whose outer rim consists of an elastic element made of elastomeric material. 20. Equipment for cutting by notching according to claim 19, characterized in that the elasticity of said elastomeric material is sufficient that, at working pressure, the cutting disk enables it to pass completely through the flat material being cut. 21. Equipment for slitting flat material, for performing a line with arranged slits with freely predetermined spacing, of the type in which the flat material passes between an opposite roller and a cutting disc having an interrupted cutting edge, characterized in that said disc for cutting associated with at least one coaxial support and drive wheel, wherein the support wheel has a variable diameter and which is made with an internal cavity of variable volume, being enclosed in an elastomeric seal extending from the wheel so as to form its outer support rim. 22. The notching equipment of claim 21, wherein the volume of said internal cavity varies in response to electromagnetic control associated with said wheel. 23. Equipment for slitting flat material, for performing a line with arranged slits with freely predetermined spacing, of the type in which the flat material passes between an opposite roller and a cutting disc having an interrupted cutting edge, characterized in that said disc for cutting associated with one or more coaxial similar cutting discs, wherein the interspaces of each of said cutting discs are located in relation to at least one cutting element of one or more discs. 24. Equipment for slitting flat material, for performing a line of arranged slits with freely predetermined spacing, of the type in which the flat material passes between an opposite roller and a cutting disc having an interrupted cutting edge, characterized in that said disc for cutting associated with one or more coaxial similar discs. 25. Notching equipment according to claim 24, characterized in that it has two said discs and said support wheel is inserted between them. 26. Grooving cutting equipment according to claims 17 or 18, characterized in that one coaxial supporting and driving wheel is associated with said cutting disc and toothed disc, wherein said wheel has an outer rim consisting of an elastic element made of an elastomeric material.