MACHINE FOR FORMING FILTER-BAGS FOR INFUSION PRODUCTS

WITH FOLDING STATIONS

Technical field

This invention relates to a machine for making filter-bags for infusion products. Background art

The expression "infusion products" means products such as tea, coffee, camomile (in powder, granules, or leaves).

More specifically, a machine according to the invention is used for forming filter-bags of the so-called two-lobed type, that is to say, filter-bags comprising a single piece of filter paper defining two separate and closed chambers. Each chamber contains a dose of infusion product. The two chambers are folded towards each other forming a single upper end (in the shape of an upturned "V") and a bottom end in the shape of a "W". The filter-bag may also be equipped with a thread for association with a gripping tag.

Patent document EP765274 (by this Applicant) describes a machine for forming a filter-bag of the type described.

That patent document describes a machine structured along a forming and feeding line on which are positioned:

- a station for feeding a web of filter paper along a feed surface;

- a station for feeding doses of product on the web of filter paper at predetermined distances;

- a station designed to close the web on itself, wrap the doses of product and, subsequently, longitudinally join the web;

- a station for folding individual pieces of filter paper with double chamber; - a carousel equipped with radially protruding grippers, positioned beneath the folding station and configured to receive individual pieces of folded filter paper; the carousel, moved stepwise about a horizontal axis, moves each piece of filter paper in the proximity of stations arranged one after another to associate to the piece of filter paper a thread, suitably wrapped around the piece of filter paper, and a tag in turn associated with the thread.

In some machine solutions, depending on the type of filter-bag, there may be:

- a further station for transversal closing of the ends of the piece before or at the same time as the separation from the remaining film; or

- a station for folding the open ends of the two chambers of the piece along the path of the carousel.

If necessary, there may also be a station for applying an overwrapping material to the filter-bag thus obtained along the path of the carousel.

Of particular relevance to this specification is the station for folding the pieces of filter paper.

This station comprises:

- a pair of fixed supporting surfaces configured with an extension convergent to each other, to define a channel for descent towards the underlying carousel with radial grippers;

- a pair of gripper elements designed to make contact with both sides of a piece of filter paper, which are movable between the fixed surfaces and towards and away from the carousel for picking up from the receiving station, folding in conjunction with the fixed surfaces, and transferring the piece of filter paper to a gripper of the carousel.

More specifically, the purpose of the pair of gripping elements is to guide the tubular piece of filter paper from a rectilinear configuration to a configuration folded in two parts placed side by side.

Once folded, the piece of filter paper is delivered to a gripper of the carousel. The two gripping elements have operational ends configured to form a fold in the shape of a "W" in a middle part of the piece of filter paper and guide in a controlled manner the piece of filter paper towards the carousel.

Moreover, the folding station comprises two presser elements, movable in synchrony with the gripper elements, designed to hold the free ends (opposite each other) of the piece of filter paper being formed against the fixed supporting surfaces in such a way as to prevent the product from escaping.

It should be noted that the presser elements come into contact with the piece of filter paper after the arrival of the piece above the fixed supporting surfaces, during the step of forming the "W" fold and in the first step of a controlled lowering of the piece of filter paper towards the carousel.

For filter-bags of standard size and weight, the station structured in this way has high level precision and operational reliability characteristics. Both for market strategies and in order to increase the infusion quality of each single filter-bag, it is necessary in every chamber to increase the quantity of product inside the filter bag with a relative increase in weight, which, in effect, has created drawbacks on the machine, in particular in the folding station.

More in detail, precisely due to the increase in weight, it is difficult to position correctly on the fixed supporting surfaces, and fold, the piece of filter paper, which tends to fall by gravity in an uncontrolled manner towards the lowering channel, before the gripping units enter into operation.

Disclosure of the invention

The aim of this invention is to provide a machine for forming filter-bags containing infusion products which can overcome the above-mentioned drawbacks.

More specifically, the aim of this invention to provide a machine for forming filter-bags for infusion products which is able to operate at high production speed even with heavy and large filter-bags.

These aims are fully achieved by a machine for forming filter-bags containing infusion products according to claim 1 .

More specifically, the machine according to the invention comprises a folding station, designed to fold a piece of filter material and positioned along a forming and feeding line, and a receiving carousel designed to receive from the folding station and move the piece of filter material to at least one operating station designed to make a filter-bag starting from the piece of filter material.

An example of filter material is filter paper, which is referred to hereinafter in the description for reasons of simplicity, but it is understood that the invention applies with any filter material suitable for be folded in the form of filter bags for infusion products, such as, for example with polymeric materials.

The folding station comprises two receiving surfaces designed to receive the piece of filter paper and having respective mutually converging surfaces to define a channel facing towards the receiving carousel.

The folding station also comprises a pair of gripping elements operatively positioned on opposite sides of the channel and movement means designed to move with a synchronised reciprocal movement the pair of gripping elements towards, and away from, the receiving carousel.

Moreover, the gripping elements are configured to act on both sides at an intermediate zone of the piece of filter paper positioned along the receiving surfaces for folding in conjunction with the receiving surfaces, and transferring to the receiving carousel, the piece of filter paper.

According to the invention, the folding station also comprises two flat auxiliary walls, one for each receiving surface.

The flat auxiliary walls are movable between an operating position for receiving, wherein the flat auxiliary walls receive the piece of filter material advancing along a feed line and are mutually coplanar, and an operating position for controlled release, wherein the flat auxiliary walls are inclined towards the channel defined by the receiving surfaces and are designed to release in a controlled manner the piece of filter paper to the receiving carousel.

Advantageously, the receiving carousel is positioned beneath the folding station.

The folding station also comprises movement devices, synchronised with the movement means, designed to move the flat auxiliary walls from the operating position for receiving to the operating position for controlled release and vice versa. In other words, each flat auxiliary wall is connected to movement devices synchronised with the movement means of the gripping elements, to move each flat auxiliary wall from a first operating position for receiving the piece of filter paper, wherein the two flat walls are coplanar with each other and parallel to the feed line, to a second operating position for controlled release of the piece of filter paper, wherein the two flat walls are inclined towards the channel defined by the receiving surfaces.

Also, advantageously, the folding station comprises two presser elements, each located above a respective receiving surface and movable in a synchronised fashion with the gripping elements between a raised non- operating position, wherein the presser element are spaced apart from the receiving surfaces, and an operating position for retaining, wherein the presser elements are in contact with, and push against the relative receiving surface, corresponding free ends of the piece of filter paper, at least at the first operating position of the flat auxiliary walls.

Thanks to a machine structured in this way, the pieces of filter paper are positioned horizontally on the auxiliary flat walls and, only after being received and locked by the gripping elements and/or the presser elements, are folded and moved towards the receiving carousel. There is, therefore, no uncontrolled falling or errors in positioning of the piece of filter paper, because until the piece of filter paper is locked by the gripping elements and/or by the presser elements, it remains resting on a horizontal surface formed by the flat auxiliary walls. Brief description of the drawings

These and other features of the invention will become more apparent from the following detailed description of a preferred, non-limiting embodiment of it, with reference to the accompanying drawings, in which:

- Figure 1 illustrates a perspective view, with some parts cut away in order to better illustrate others, of a folding station of a machine according to the invention in a configuration for receiving a piece of filter paper (not illustrated);

- Figure 2 illustrates a perspective view, with some parts cut away in order to better illustrate others, of the folding station of Figure 1 in a configuration for folding the piece of filter paper;

- Figures 3 to 6 illustrate front views, with some parts cut away to better illustrate others, of the folding station of Figures 1 and 2, in a corresponding series of operating configurations in which it receives, folds and conveys the piece of filter paper towards a receiving carousel positioned below the folding station. Detailed description of preferred embodiments of the invention

With reference to the accompanying drawings, in particular Figures 3 to 6, a machine according to the invention, labelled 100 in its entirety, is used for forming filter-bags containing infusion products.

The expression "infusion products" means products such as tea, coffee and camomile dosed in powder, granules, or leaves.

The filter-bag formed by a machine according to the invention comprises a piece 1 of filter paper with an elongate shape (tubular) having at least two chambers 2, 3 containing corresponding doses D1 and D2 of infusion product and separate from each other.

The two chambers 2, 3 are folded towards each other forming a single upper end (in the shape of an upturned "V") and a bottom end in the shape of a "W".

The machine 100 comprises, along a forming and feeding line L, a plurality of stations (of known type and therefore not illustrated) designed to cut and form a piece 1 of filter paper with the two chambers 2, 3 (containing the doses D1 and D2) separated by an intermediate zone 1 a.

The machine 100 also comprises, again along the forming and feeding line L, a folding station 4, designed to fold opposite ends of the piece 1 of filter paper and comprising at least two receiving surfaces 5, 6 designed to receive the piece 1 of filter paper. The receiving surfaces 5, 6 have surfaces mutually converging to define a channel 7 facing towards an underlying receiving carousel 8 designed to receive the piece 1 of filter paper once it has been folded in the folding station 4 (the receiving carousel 8 is only partly illustrated with a dashed line in Figure 6).

The receiving surfaces 5, 6 have a curved shape which determines a mutual moving towards each other of the chambers 2, 3 whilst the piece 1 of filter paper approaches the receiving carousel 8.

The folding station 4 also comprises a pair of gripping elements 9, 10 operatively positioned on opposite sides of the channel 7 and movement means 1 1 designed to move with a synchronised reciprocal movement the pair of gripping elements 9, 10 towards, and away from, the receiving carousel 8.

The gripping elements 9 and 10 act on both sides, at the intermediate zone 1 a, on the piece 1 of filter paper for folding (from a flat configuration to a configuration with chambers side by side, Figures 3-5), and transferring (Figure 6) to the underlying receiving carousel 8, the piece 1 of filter paper.

According to the invention, the folding station 4 comprises two flat auxiliary walls 12, 13, one for each receiving surface 5, 6.

The flat auxiliary walls 12, 13 are movable between an operating position for receiving, wherein the flat auxiliary walls 12, 13 receive the piece 1 of filter paper advancing along a feed line and are mutually coplanar Figures 3 and 4), and an operating position for controlled release, wherein the flat auxiliary walls 12, 13 are inclined towards the channel 7 defined by the receiving surfaces 5, 6 and are designed to release in a controlled manner the piece 1 of filter paper to the underlying receiving carousel 8 (Figured 5 and 6).

In detail, the flat auxiliary walls 12, 13 in the operating position for receiving are positioned horizontally one after the other along the feeding and forming line L and define a support surface for the piece 1 of filter paper. The flat auxiliary walls 12, 13 in the operating position for receiving can be positioned mutually at a distance such as to leave an opening, which is small enough such as no to allow the piece 1 of filter paper to fall be gravity towards the channel 7.

The folding station 4 also comprises movement devices 14, synchronised with the movement means 1 1 , designed to move the flat auxiliary walls 12, 13 from the operating position for receiving to the operating position for controlled release and vice versa.

Preferably, each flat auxiliary wall 12, 13 comprises a movable portion of the corresponding receiving surface 5, 6 (see Figures 1 , 2).

It should be noted that each flat auxiliary wall 12, 13 comprises a supporting grille 15, connected, at one end 15a, to an articulation shaft 16 connected to the movement devices 14.

Preferably, each receiving surface 5, 6 is formed by a box-shaped frame 17 having a curved active surface 18 and a flat receiving surface 19 parallel to the feeding line L.

In light of this, each receiving surface 5, 6 comprises a plurality of grooves

20 which are longitudinal and mutually parallel, designed to be engaged by a corresponding supporting grille 15 positioned in the second operating position for controlled release.

In other words, the configuration of the flat auxiliary walls 12, 13 and the receiving surfaces 5 and 6 is such that, in the operating position for controlled release, the flat auxiliary walls 12, 13 are substantially hidden inside the box-shaped frame 17.

It should be noted, therefore, that in the operating release position only the receiving surfaces 5, 6 define respective supporting surfaces of the piece 1 of filter paper.

Advantageously, the articulation shaft 16 is housed in the box-shaped frame 17 of a corresponding receiving surface 5, 6 and beneath a corresponding flat receiving surface 19.

In light of this, the devices 14 for moving the flat auxiliary walls 12, 13 comprise a crank 21 for each articulation shaft 16.

The cranks 21 are mutually connected by a control rod 22 which is able to mutually synchronise the movements of the flat auxiliary walls 12, 13. Moreover, the rod 22 is connected to actuator devices 23, which are connected to centralised cam means (not illustrated) which are designed to synchronise the steps for movement of the flat auxiliary walls 12, 13 with the movement members 1 1 , the gripping elements 9, 10 and with the movement (in a step-like fashion) of the receiving carousel 8.

The actuator devices 23 can, for example, comprises levers connected to the cam means which are centralised and able to directly control the movement of the control rod 22.

Moreover, the folding station 4 comprises two presser elements 24, 25, each located above a respective receiving surface 5, 6 and movable in a synchronised fashion with the gripping elements 9, 10 between a raised non-operating position (Figures 1 , 3, 4 and 6), wherein the presser elements 24, 25 are spaced apart from the receiving surfaces 5, 6, and an operating position for retaining (Figure 5), wherein the presser elements

24, 25 are in contact with corresponding free ends of the piece 1 of filter paper, at least at the first operating position of the flat auxiliary walls 12, 13.

Once the presser elements 24, 25 have made contact with and blocked the free ends of the piece 1 of filter paper against the receiving surfaces 5,

6, the flat auxiliary walls 12, 13 move from the operating position for receiving, wherein they support the piece 1 of filter paper, to the operating position for controlled release, wherein they do not make contact with the piece 1 of filter paper which is supported just by the receiving surfaces 5, 6.

In light of this, each presser element 24, 25 has a contact head 24a, 25a configured in the form of a spatula and equipped, on one surface, with a plurality of teeth 26 which engage, in the operating retaining position, with at least one groove 20 made on a receiving surface 19 of a corresponding receiving surface 5, 6.

Thanks to the presser elements 24, 25, the piece 1 of filter paper fed on the flat auxiliary walls 12, 13 is secured at the ends during a first step of gripping on both sides by the gripping elements 9, 10, and then be accompanied during the lowering step. It should be noted that during the lowering step there is no risk of escape of product from the piece 1 of filter paper precisely because the contact heads 24a, 25a of the presser elements 24, 25 keep the ends the piece 1 of filter paper pressed against the receiving surfaces 5, 6.

It should be noted that the presser elements 24, 25 comprise a pair of shafts which support the heads 24a and 25a and are articulated in a shared axis, positioned on top of the heads 24a and 25a. The pair of shafts forms a sort of compass which, in the open position, allows the heads 24a and 25a to come into contact with corresponding ends of the piece 1 of filter paper which are therefore blocked between the heads 24a and 25a and the respective receiving surfaces 5, 6.

The pair of shafts, when closing and lowering, allow the heads 24a and

25a to follow the ends of the piece 1 of filter paper which slides downwards along receiving surfaces 5, 6 pulled by the gripping elements 9, 10.

Lastly, the pair of shafts can move upwards (detaching from the piece 1 of filter paper) and be positioned in the open position, to allow the heads 24a and 25a to come into contact with a succession of pieces 1 of filter paper. The gripping elements 9, 10 each have a respective operating head 9a, 10a, mutually shaped to define a fold in the form of a "W" at the intermediate zone 1 a of the piece 1 of filter paper. In short, the gripping elements 9, 10 embed the intermediate zone 1 a of the piece 1 of filter paper, forming the fold in the shape of a "W".

The heads 9a, 10a of the gripping elements 9, 10 are connected to, and moved by, corresponding supporting arms.

The receiving carousel 8 comprises a plurality of radial gripping arms 8a defining individual housings for the pieces 1 of filter paper.

In short, the folding occurs in the following manner:

- receiving the piece 1 of filter paper, advancing along the feed line, on the flat walls 12, 13 positioned mutually coplanar in an operating position for receiving (Figure 3);

- bilateral movement of the gripping elements 9, 10 to the intermediate zone 1 a of the piece 1 of filter paper (Figure 4);

- locking the ends of the piece 1 of filter paper by means of the presser elements 24, 25, gripping on both sides of the piece 1 of filter paper at the intermediate zone 1 a by the gripping elements 9, 10 and simultaneous forming of the fold in the shape of a "W" (Figure 5);

- pulling the piece 1 of filter paper by the gripping elements 9, 10 towards the underlying receiving carousel 8 through the channel 7, whilst the presser elements 24, 25 follow downwards, and keep pressed against the flat auxiliary walls 12, 13, the ends of the piece 1 of filter paper and the flat auxiliary walls 12, 13 incline towards the channel 7 (Figure 6).

In detail, the flat auxiliary walls 12, 13, in a position of maximum inclination, align with the active surfaces 18 in a final stage of folding the piece 1 of filter paper, before being received by a radial gripper arm 8a of the receiving carousel 8.

From this description it is clear that, thanks to the machine structured in this way the piece of filter paper is always correctly positioned and kept under control during the folding step. PAGE LEFT INTENTIONALLY BLANK