METHOD FOR MAKING A PACKAGE FOR GROUPS OF PRODUCTS AND MACHINE IMPLEMENTING THE METHOD

Technical field

This invention relates to a method for making a package for groups of products for sanitary use and relative machine implementing the method, in particular, but without restricting the scope of the invention, rolls of "tissue" products such as, for example, rolls of paper for sanitary and/or household use or unwoven products such as nappies.

Background art

More specifically, this description focusses attention on bagging machines which are, usually, used for wrapping a certain number of groups of products already packed using plastic film, but without limiting the range of protection in question, since the groups of products can also be a plurality or batches of loose products.

These groups of products are grouped together in accordance with formats of pre-defined batches and then fed, in succession, in a tubular wrapping of film.

These bagging machines, which define, usually, an end station of machines for making the above-mentioned groups of products, bag the groups of products in tubular wrappers defined automatically by the bagging machine on the products to be wrapped.

Such machines are known from the patent documents US 4 679 379, US 2015/329230 and US 2008/209866.

In practice, the machine forms the wrapper from a flat strip of film of wrapping material (fed from a reel located below a plane of movement of the groups of products) and which, by means of special folding elements (called folding ties), is progressively folded back on itself in such a way as to generate a tubular shape, supported from the inside of the wrapper being formed by suitable supporting elements or walls (so as to define a "tunnel" with a quadrangular cross section), and having longitudinal flaps positioned next to and superposed on each other along the upper surface of the tunnel.

There are, moreover, the first sealing elements located at the front of the wrapper and the folding elements, oriented transversely to the tubular shape, which then allow the wrapper to be sealed, transversally, in such a way as to form, in sequence, a closed front end and rear end.

Lastly, second sealing elements, oriented longitudinally to the wrapper and facing the above-mentioned longitudinal flaps, close the tubular wrapper longitudinally in such a way as to completely close the wrapping.

Basically, the process for forming the wrapping on the groups of products comprises the following steps:

- forming the wrapping with the film around the above-mentioned folding elements and the supporting elements or walls;

first head sealing of the wrapping film;

inserting into the channel formed by the four walls of the folders a predetermined number of groups of products, until making contact with the closed front end of the wrapper;

further feeding of the groups of products beyond the above- mentioned transversal sealing elements, with simultaneous feeding of the film from the reel thanks to the pushing of the products, and relative forming of the wrapping, as the front closed end feeds along the machine with the products introduced;

at the same time as forming the wrapping, longitudinal sealing of the above-mentioned superposed flaps of film occurs using the above-mentioned second sealing elements;

further activation of the first transversal sealing elements designed to close the wrapper behind the products already bagged;

separating cut of the bag thus obtained from the rest of the film, using cutting elements, thus starting a new and subsequent cycle for bagging the groups of products.

However, this machine and the relative method have several drawbacks. A first drawback is due to the fact that the structure of the frame defining the channel for the groups of products determines a separation between wrapping film (wound around the frame) and the products and, consequently, the package is often obtained with slack or "loose" side walls with reduced rigidity of the pack and greater difficulty in the subsequent storage.

Another drawback is due to the fact that actual feeding of the film is accomplished through the pushing of the group of products on the sealing head and, consequently, to prevent breakage of the bottom/top of the bag it is necessary to reduce the machine cycle time to guarantee a perfect sealing of the flaps which form the bottom/top.

In addition, there is the fact that the market to which this machine is directed requires the further specifications that the machine structured as described above cannot meet.

One of these relates to the possibility of modifying, that is to say, reducing, the overall size of the group of products.

The other need is given by the reduced flexibility of the machine due to the difficult and laborious modification of the size of the tunnel during format changeover which, often, requires the complete change of the supporting walls and, in some cases, even of the folders or ties. Disclosure of the invention

The aim of this invention is to provide a method and a machine for making a package for groups of products for sanitary use which overcomes the above-mentioned disadvantages of the prior art.

More specifically, the aim of this invention is to provide a method and a machine for making a package of groups of products for sanitary use which are able to modify, during the wrapping cycle step, the overall size, by reducing, the group of products.

A further aim of this invention is to provide a method and a machine for making a package for groups of products for sanitary use with high operational flexibility without modifying the basic structure of the machine. These aims are fully achieved by the method and by the machine for making a package for groups of products for sanitary use according to the invention, as characterised in the appended claims.

Brief description of drawings

Further features of the invention will become more apparent from the following detailed description of a preferred, non-limiting embodiment of it, illustrated by way of example in the accompanying drawings, in which:

Figure 1 illustrates schematic perspective top view of a machine for making a package of groups of products for sanitary use, according to this invention, and implementing the method for forming the package of groups of products;

Figure 2 illustrates a rear view, with some parts cut away, of the machine of Figure 1 ;

Figure 3 illustrates a perspective view, with some parts cut away, of the load-bearing frame of the machine of the previous drawings;

Figure 4 illustrates a rear view of a diagram of the main parts of the machine of the previous drawings;

Figure 5 illustrates a rear view of the machine of the previous drawings showing the anti-bending contrast elements.

Detailed description of preferred embodiments of the invention

With reference to the accompanying drawings, and in particular Figure 1 , the method and the machine according to the invention are used for making a package for groups of products for sanitary use, such as, but without restricting the scope of the invention, rolls of "tissue" products such as, for example, rolls of paper for sanitary and/or household use or unwoven products such as nappies.

More specifically, the machine according to the invention (and the relative method) is a bagging machine which is used for wrapping a certain number of groups of products already packaged using plastic film or for bagging of groups of products formed by batches of loose products.

The method for making a package 1 of groups 2 of products for sanitary use comprises at least the following steps:

a forming of a length of tubular film by means of continuous film 3 around a frame 4 comprising elements 5 for folding the film 3 and a plurality of walls 6, 7 forming a tubular channel 8 for the passage of the groups 2 of products; the tubular channel 8 has a width L and a height H;

a first join, wherein head flaps of the film 3 are joined to form a head end, using first transversal joining elements 9 positioned close to the front end of the frame 4 relative to a feed direction A of the groups 2 of products;

inserting in the tubular channel 8, in the feed direction A and using a pushing unit 10, a predefined number of groups 2 of products, advancing until close to the closed head end of the film 3 to form a first portion of the package 1 ;

further feeding of the groups 2 of products beyond the first joining elements 9, with simultaneous feeding of the film 3 and relative forming of a further portion of the package 1 beyond the frame 4; a second join, wherein the longitudinal superposed flaps of the film 3 are joined by second longitudinal joining elements 1 1 , simultaneously with the further feeding step;

a third join, wherein the tail flaps of the film 3 are joined, using the first transversal joining elements 9, in order to close the package 1 at the rear of the groups 2 of products bagged.

As illustrated (see Figures 2 to 5) at least between the step of introducing the groups 2 of products in the tubular channel 8 and the step of further feeding the groups 2 of products beyond the first transversal joining elements 9 there is a step of modifying (temporary) the size of the tubular channel 8 using a movement device 12 for moving the frame 4 in such a way as to reduce the cross section of the tubular channel 8 and obtain a reduction in the overall size of the groups 2 of products by flattening them. In other words, the groups 2 of products inserted in the tubular channel 8 undergo a flattening which is able (at least temporarily) to reduce their size (preferably, as described below, in terms of width).

This allows, together with an adaptation of the film 3 (as described in more detail below), the final package 1 to be made which is extremely compact and stable, also with a saving in the quantity of film used.

Preferably, the step of modifying the size of the tubular channel 8 is given by the reduction in the width L of the channel 8.

Preferably, the step of modifying the size of the tubular channel 8 is given by the reduction in the width L of the channel 8 and occurs with the groups 2 of products completely housed in the tubular channel 8 and feeding along the tubular channel 8.

In short, the step of reducing the width L of the channel 8 may be of the dynamic type (movement of side walls 7 of the channel 8 simultaneously with the sliding movement of the groups 2 of products): thanks to these type of steps, the machine cycle times remain substantially unaltered. Alternatively, the step of modifying the size of the tubular channel 8 is again given by the reduction in the width L and occurs with the groups 2 of products completely housed in the tubular channel 8 and stationary inside the tubular channel 8, whilst the side walls 7 move.

In this case, the step of reducing the width L of the channel 8 may be of the static type (movement of the walls 6 of the channel 8 with groups 2 of products provisionally stationary): this type of choice might be useful if it is necessary to wait a few seconds to allow a correct adhesion in the joining of the tail flaps of the package previously obtained.

Preferably, the step of modifying the width of the tubular channel 8 occurs by a movement step, which is translational and towards each other, of at least two side walls 7 of the frame 4 forming the tubular channel 8.

In light of this, the step of modifying the width L of the tubular channel 8 also occurs by a movement step (which is translational and towards each other) of the folding elements 5 in such a way as to adapt also the extension of the film 3 around the frame 4 to the different perimeter dimension reached by the tubular channel 8.

It should be noted that, after the third step of joining the tail flaps of the film 3 there is a step of restoring the previous size (width L) of the tubular channel 8.

In this way, the next cycle starts again with the dimensions of the tubular channel 8 decided on the size of the groups 2 of products decided originally.

This invention, as mentioned, also provides a machine, labelled 100 in its entirety, for making a package 1 of groups 2 of products for sanitary use. The machine 100 comprises a station 13 for feeding a continuous wrapping film 3 (for example a roll of film).

The machine 100 also comprises a frame 4 for forming a tubular length of the continuous film 3.

The frame 4 has folding elements 5 and a plurality of walls 6, 7 forming a tubular channel 8 for the passage of the groups 2 of products and on which the continuous film 3 is wound.

The tubular channel 8 has a width L and a height H.

The machine 100 also comprises a pushing unit 10 for moving a predetermined number of groups 2 of products inside the tubular channel

8 in a feed direction A.

Moreover, the machine 100 has first transversal joining elements 9 located downstream of the frame 4, relative to the feed direction A, and designed to join, respectively, the head flaps of the film 3, prior to the arrival of the groups 2 of products, and the tail flaps of the film 3 after the passage of the groups 2 of products wrapped in film 3 beyond the first transversal joining elements 9.

The machine 100 also comprises second longitudinal joining elements 1 1 located close to the frame 4 (above the latter), and designed to join two longitudinal superposed flaps of the film 1 at the formation of the package 1 .

As illustrated, the machine 100 comprises at least two of the walls 6, 7 forming the channel 8 movable towards and away from each another by a movement device 12 connected to the frame 4, so as to allow the modification, at least temporarily, of the size of the tubular channel 8 in order to reduce the cross section of the tubular channel 8 during the passage of the groups 2 of products and to obtain a reduction in the overall size of the groups 2 of products by flattening them.

It should be noted that the tubular channel 8 may be formed by a set of separate walls (lower, upper and side) to form the channel 8, or by two individual C-shaped profiles facing each other (configuration not illustrated), or, also, by four corner segments which make up the bottom and top walls 6 and the side walls 7 (see Figures 4 and 5).

The folding elements 5 are formed by two pairs of flaps 5a and 5b positioned on both sides of the tubular channel 8 and by a pair of intersecting plates 5c positioned above the tubular channel 8 for guiding and retaining the superposed free flaps of the film 3 before they are joined with the second longitudinal joining elements 1 1 .

It should be noted that the first transversal joining elements 9 comprise two sealing bars positioned beyond the outlet of the tubular channel 8 combined with a knife (not illustrated) for the separation of the completed package 1 from the subsequent package being formed.

The second longitudinal joining elements 1 1 comprise a sealing head configured to hot seal the superposed flaps of the film 3.

Preferably, the movement device 12 comprises at least a first shaft 14 with motor-driven screw and rotatably connected to a pair of vertical supporting arms 15 associated with the side walls 7 of the frame 4 (see Figures 2 to 5).

The first screw shaft 14 is configured for moving, in both directions, the pair of arms 15 so as to allow a movement towards and away from each other, thereby obtaining a variation, even temporary, of the width L of the tubular channel 8.

In light of this, the first screw shaft 14 has two threads in opposite directions, separate from each other to allow, during its rotation (in either direction), the movement towards or away from each other of the arms 15. Preferably, the device 12 comprises a second shaft 16 with a motor-driven screw positioned parallel to the first screw shaft 14 which is motor-driven and rotatably connected to vertical arms 17 supporting the folding elements 5.

In light of this, the second screw shaft 16 is configured for moving, in both directions, the vertical supporting arms 17 so as to allow a movement towards and away from each other, thereby obtaining a variation, even temporary, of the dimensions of the folding elements 5.

The modification of the folding elements 5 is correlated with the modification of the width L of the tubular channel 8 in such a way as to adapt the superposed flaps of the film 3 to the new size.

It should be noted that the first 14 and the second 16 screw shaft are connected to a single drive unit M (for example by means of transmission belts).

Alternatively, the two screw shafts 14 and 16 may be connected to independent drive units.

The machine 100 comprises the sensors 18 for detecting the compressive force connected at least to the first screw shaft 14 (but they might also be connected to the second screw shaft 16) and configured to send a corresponding signal relating to the compressive force value to a control unit 19 connected to the drive unit(s) M.

According to an embodiment (see Figure 4), but without limiting the scope of the invention, the detection sensors 18 may be of the load cell type interposed between the first arms 15 and the side walls 7 in such a way as to check the compressive force imparted by the first arms 15 on the side walls 7.

In light of this, the control unit 19 is programmed for turning ON or OFF the drive unit(s) M for moving the side walls 7 and the folding elements 5 by a stroke equivalent to a compression value between a minimum and a maximum stroke range, as a function of a plurality of parameters preset in the control unit 19 and the detection signal sent by the detection sensors 18.

In other words, the control unit 19 has memory banks in which are set the predetermined minimum and maximum compression values and calculated as a function, for example, a series of parameters, starting from the type of final format of the package to be obtained:

type of product (roll or nappy, for example);

- package softness defined, for example, by the density of the product (roll or nappy, for example);

configuration of the pack or bag to be formed (in the case of groups of packages side by side or groups of loose products).

Based on these parameters, therefore, there will be different thresholds (minimum and maximum stroke).

The activation of the motor(s) M determines the start of the compression stroke and, when the compression value recorded by the sensors 18 enters the desired threshold (ranging between the minimum and a maximum values), the unit 19 may already stop the motor(s) M.

Obviously, the compression may be increased, upon the decision of the operator, but only until reaching the maximum set value.

The machine 100 also comprises dynamic contact elements 20 associated with the folding elements 5 and positioned outside and at a predetermined distance from the two side walls 7 of the frame 4 (see Figure 5).

In light of this, the dynamic contact elements 20 are configured to oppose, if necessary, a deformation, towards the outside, of the side walls 7 of the frame 4.

The dynamic contact elements 20 have the capacity, once in contact with the corresponding side wall 7, to make a counter push on the wall itself, but at the same time to avoid any block on the feed movement of the wrapping film 3.

As illustrated in Figure 5, these contact elements 20 may consist of rollers which can turn idly and are connected (by means of supporting shafts) to the folding elements 5.

The rollers 20 are arranged a few millimetres away from the corresponding side wall 7 and they adapt to the movement of the side walls 7 thanks to the translation of the folding elements 5.

If there is a bending of the side walls 7 due to their compression, the rollers 20 are designed to oppose this movement towards the outside, maintaining the parallelism of the walls 7 and their position in compression. Moreover, since the rollers 20 can rotate freely, they do not oppose the feed movement of the film 3 during the step of packaging the groups 2 of products.

As an alternative to the rollers 20 there may be motor-driven belts (not illustrated) looped on pairs of pulleys and again supported by the folding elements 5.

Also in this case, if a branch of the belt is resting on the walls, it allows the film 3 to feed along the side walls 7 during the step of packaging groups 1 of products.

Thanks to this packaging method and the respective packaging machine the preset aims are achieved.

Thanks to the "on time" controlled compression system, the groups of products are reduced in size in terms of width in a short time and without excessively altering the machine structure.

Together with the compression there is, simultaneously, an adaptation of the extension of film so as to make the final package extremely compact and stable, also with a saving in the quantity of film used.