MACHINE FOR MAKING FILTER BAGS WITH INFUSION PRODUCTS Technical field

This invention relates to a machine for making filter bags with infusion products, such as tea, coffee, camomile and the like, in particular single- chamber or single-lobe filter bags.

Background art

There are prior art machines of a vertical type for the production of single- chamber or single-lobe filter bags containing infusion products, wherein the filter bags being formed move forward along a feed-production line which is substantially vertical.

An example of a vertical type machine is known from patent WO201 1 tt 35409 in the name of the same Applicant.

The machine described in WO201 1/135409 comprises:

- a feeding station designed to feed a strip of filter material;

- a forming and joining station designed to form the strip in a tubular shape and designed to advance the strip in a tubular shape along a vertical feed direction;

- a dosing station designed for dosing the infusion product and positioned above the forming and joining station;

- a closing station designed to close an open portion of the strip in the tubular shape defining, simultaneously, a top end of a filter bag being formed and a bottom end of the next filter bag;

- a cutting station designed to separate a filter bag formed from a next filter bag being formed positioned along the vertical feed axis, downstream of the closing station.

Downstream of the cutting station there can be application stations designed for applying string and tag to the individual filter bags, and stations designed to pick up and carry the filter bags towards a stacking and/or packaging station.

These stations are structured, for example, as carousels rotating in a stepwise fashion about horizontal axes.

The machine just described, which is itself is reliable, has several drawbacks.

More in detail, the machine operates intermittently (step-wise) and thus has limited productivity.

Moreover, the machine has a relatively complex structure and operation, comprising a pair of drive grippers which must be moved in a synchronised fashion so as to always have a drive gripper holding on the strip with the tubular shape. Moreover, once the filter bags have been cut, complex gripping systems are necessary for carrying the filter bags towards successive stacking and boxing stations.

The machine also has reduced flexibility: in fact, the cutting station separates always and only single filter bags from the strip with the tubular shape, because the stations located downstream of the cutting station are designed for processing only individual filter bags. Therefore, it is not possible to form groups of two or more filter bags partly separated by dashed pre-cut lines, designed to be housed in suitable boxes.

Disclosure of the invention

The aim of this invention is to provide a machine and a method for making filter bags for infusion products, such as tea, camomile, herbs, etc., which overcome the above-mentioned limitations and drawbacks.

According to the invention, this and other aims are achieved by a machine and a method according to the claims, which form an integral part of this description. Brief description of the drawings

The invention will now be described with reference to the accompanying drawings, which illustrate a preferred non-limiting example embodiment, and in which:

Figure 1 is a schematic front view of a machine for making filter bags for infusion products according to the invention, with some parts cut away in order to better illustrate others;

Figure 2 is a schematic front view of a detail P of the machine of Figure 1 , in enlarged scale.

Detailed description of preferred embodiments of the invention

A machine 100 according to the invention is used for producing filter bags 1 with infusion products (such as tea, coffee, camomile, etc.) from a continuous strip S of filter material.

The filter bags 1 , in the embodiment illustrated by way of example only, are of the single-chamber or single lobe type, with top 1 a and bottom 1 b, without string, tag and sheet of overwrapping material.

In this description, the term filter material includes a plurality of materials selected between filter paper, heat-sealable filter paper, woven/non-woven plastic materials, and other known materials for infusion products.

As illustrated, the machine 100 for making filter bags 1 with infusion products comprises a feeding station 2 configured for feeding the strip S of filter material and a forming and joining station 3 configured to pre-form the strip S of filter material into a closed tubular shape.

At the forming and joining station 3, the strip S is fed along a first feed direction Z. Advantageously, the first feed direction Z is vertical.

The machine 100 also comprises a dosing station 4 configured for dosing the infusion product inside the strip S of filter material with a closed tubular shape. The filling station 4 is positioned above the forming and joining station 3.

The machine 100 also comprises a closing station 5 configured for closing an open portion of the strip S with a closed tubular shape and defining, simultaneously, the top 1 a of a filter bag 1 being formed and a bottom 1 b of a next filter bag 1.

Basically, the closing station 5 forms a continuous strip S1 of filter bags 1 (already formed). In other words, the closing station 5 transforms the strip S into a closed tubular shape of a continuous strip S1 of filter bags 1 .

In light of this, the closing station 5 is positioned downstream of the forming and joining station 3 along the first feed direction Z.

Moreover, the machine 100 comprises, downstream of the closing station 5 along the first feed direction Z, a drive member 6 configured to intercept a continuous strip S1 of filter bags 1 , advancing along the first feed direction Z, and able to divert the continuous strip S1 of filter bags 1 from the first feed direction Z to a second feed direction T, transversal to the first feed direction Z.

Advantageously, the second feed direction T is horizontal.

More advantageously, the first feed direction Z is vertical and the second feed direction T is horizontal.

The machine 100 also comprises a separating station 7, configured to separate groups of one or more filter bags 1 from the continuous strip S1 of filter bag 1 and positioned downstream of the drive member 6.

Advantageously, the separating station 7 is positioned along the second feed direction T. Advantageously, the separating station 7 cuts the continuous strip S1 of the filter bag 1 transversely to the second feed direction T.

As described in more detail below, the filter bags 1 formed in the separating station 7 can be single filter bags 1 or groups of filter bags 1 jointed together in succession to define multiple formats of filter bags 1 , for example partially separated by dashed pre-cut lines, at the top 1 a of a filter bag 1 and the bottom 1 b of an adjacent filter bag 1 .

The machine 100 comprises a pulling unit 8 configured to pull the continuous strip S1 of filter bags 1 .

In light of this, the pulling unit 8 is interposed between the drive member 6 and the separating station 7 to allow a controlled pulling of the continuous strip S1 of filter bags 1 towards the separating station 7.

In other words, the machine 100 comprises in succession, advantageously along the second feed direction T, the drive member 6, the pulling unit 8 and the separating station 7.

Preferably, the drive member 6 is positioned below and at a predetermined distance D from the closing station 5 along the first feed direction Z.

Advantageously, the pulling unit 8 pulls and moves continuously the continuous strip S1 of filter bags 1.

Since the continuous strip S1 of filter bags 1 is joined to the strip S in the closed tubular shape upstream of the drive member 6, the pulling unit 8 advantageously pulls and moves continuously also the strip S in the closed tubular shape.

With reference to the separating station 7, it is particularly advantageous to handle the filter bags 1 once separated (either in groups of one or more bags), if the second feed direction T, along which the separating station is positioned, is horizontal.

Moreover, successive steps of transferring and stacking groups of filter bags 1 are particularly easy, precise and fast.

For example, the drawings illustrate a handling and stacking station 28 designed to stack groups of two filter bags 1 inside a vertical storage unit 30 located under a pusher means 29.

Preferably, the drive member 6, illustrated in detail in Figure 2, comprises a drum 61 , which rotates continuously about a horizontal axis X.

In light of this, the drum 61 has a circumferential surface on which is formed a plurality of impressions 9, each of which is shaped to match a corresponding filter bag 1 of the continuous strip S1 of filter bags 1 .

The impressions 9 allow a precise intercepting of the filter bags 1 and a consequent deviation of the continuous strip S1 of filter bags 1 from the first feed direction Z to the second feed direction T.

In a first embodiment, the separating station 7 comprises a rotary knife 10, which rotates continuously about a horizontal axis, and a fixed contrast element 1 1 . The rotary knife 10 and fixed contrast element 1 1 are positioned on opposite sides of the continuous strip S1 of filter bags 1 along the second feed direction T.

In an alternative embodiment, the separating station 7 comprises a rotary knife 10, which rotates continuously about a horizontal axis, and a rotary counter-knife 12 (illustrated with a dashed line in Figure 2), which rotates continuously and in a synchronised fashion with the rotary knife 10.

The rotary knife 10 and the rotary counter-knife 12 are positioned on opposite sides of the continuous strip S1 of filter-bags 1 formed.

The rotary knife may advantageously comprise at least one blades to cut and separate completely a filter bag 1 from the continuous strip S1 of filter bags 1 and at least one blade to form dashed pre-cut lines between adjacent filter bags 1.

In more general terms, the separating station 7 may comprise cutting means to separate adjacent filter bags 1 , and pre-cutting means designed to form dashed pre-cut lines between adjacent filter bags 1 .

In other alternative possible solutions not illustrated, the separating station

7 comprises cutting means and pre-cutting means designed to work after each other on the strip S1 of filter bags 1 .

The cutting means and the pre-cutting means are actuated in a synchronised fashion for making groups with a predetermined number of filter bags 1 , the adjacent filter bags 1 of a same group being mutually partly separated by dashed pre-cut lines.

Preferably, the pulling unit 8 comprises a pair of motor-driven belts 13, 14, located on opposite sides of the continuous strip S1 of filter bags 1 formed.

The belts 13, 14 are closed in a loop around a respective pair of rollers 15, 16; 17, 18 and configured to pull continuously the continuous strip S1 of filter bags 1 towards the separating station 7.

The belts 13, 14 perform the dual function of maintaining a constant pulling action on the continuous strip S1 of filter bags 1 (in coordination with the drive member 6, in particular with the drum 61 ) and feeding the strip S1 , in a controlled manner, to the separating station 7.

It should be noted that the feeding station 2, the forming and joining station 3 and the closing station 5 are moved continuously and in a synchronised fashion with each other.

In light of this and by way of example, the station 2 feeding for the continuous strip S (see Figure 1 ) comprises a reel holder 19 designed to house a reel of filter material, and a series of rollers 20, including at least one drive roller, a dandy roller and a motor-driven roller for feeding, continuously, the continuous strip S of filter material unwound from the reel towards the forming and joining station 3.

The forming and joining station 3 comprises a series of shaped walls 21 configured to fold and divert the strip S towards the first feed direction Z. The shaped walls 21 define a so-called 'tie' and allow the strip S to be folded in a closed tubular shape.

More specifically, free longitudinal flaps of the strip S are superposed along a direction parallel to the first feed direction Z, to form a continuous tube of filter material.

In light of this, the forming and joining station 3 comprises joining means 22 designed to join the free longitudinal flaps, once they have been mutually superposed by the tie. The joining means 22 may advantageously comprise one or more hot sealers (heated sealing rollers) or cold sealers (ultrasound sealers).

The dosing station 4 (shown in Figure 1 ) may comprise a feed hopper 23 for feeding the infusion product inside a dosing unit 24, in conjunction with a pusher element 25, to form and release individual doses of product inside the strip S in a closed tubular shape.

Advantageously, the pusher element 25 is movable in both directions along the first feed direction Z so as to accelerate the product towards the bottom 1 b already formed of a filter bag 1 being formed.

As also shown in Figure 1 , the closing station 5 may comprise a pair of sealing heads 26 and corresponding movement means 27.

The movement means 27 are configured for moving the sealing heads 26 in continuous, synchronised, roto-translation according to a trajectory substantially tracking the strip S with a closed tubular shape along the first feed direction Z.

In other words, the sealing heads 26 can:

- move towards the strip S in a closed tubular shape at an initial position to define a closed operating configuration (with the sealing heads 26 in contact on both sides with the strip S with closed tubular shape)

- maintain the closed operating configuration for a predetermined closing time sufficient to firmly close the top 1 a of the filter bag 1 being formed and the bottom 1 b of the next filter bag 1 , tracking the strip S with a closed tubular shape moving down the first feed direction Z to a final position, which is lower than the initial position; and

- move away from the continuous tubular strip and return to the initial position.

Depending on the time required to effectively close the strip S with a closed tubular shape, the initial position and the final position of the sealing heads 26 may be more or less mutually spaced apart.

Advantageously, the sealing heads 26 may comprise hot sealers, that is to say, heated rollers or heads, or cold sealers, that is to say, of the ultrasound type.

The invention also provides a method for making filter bags 1 comprising the following steps:

- forming a strip S of filter material in a closed tubular shape;

- feeding the strip S of filter material in a closed tubular shape along a first feed direction Z;

- feeding a dose of infusion product on a bottom 1 b of a filter bag 1 being formed along the first feed direction Z;

- closing an open portion of the strip S of filter material in a closed tubular shape to form simultaneously a top 1 a of a filter bag 1 being formed and a bottom 1 b of a next filter bag 1 and form a strip S1 of filter bags 1 ;

- diverting the continuous strip S1 of filter bags 1 from the first feed direction Z to a second feed direction T, transversal to the first feed direction Z;

- separating groups of one or more filter bags 1 from the continuous strip S1 of filter bags 1.

Preferably, the step of diverting the continuous strip S1 of filter bags 1 is performed continuously.

Preferably, the method also comprises a step of pulling (or dragging) the continuous strip S1 along the second feed direction T, after (or in combination with) the step of diverting the continuous strip S1 of filter bags 1 from the first feed direction Z to the second feed direction T, transversal to the first feed direction Z.

Preferably, the step of diverting the continuous strip S1 of filter bags 1 comprises partly wrapping the continuous strip S1 of filter bags 1 about a drive member 6 rotating continuously about a horizontal axis X.

Preferably, the step of forming the strip S of filter material in a closed tubular shape is performed continuously.

Preferably, the step of feeding the strip S of filter material in a closed tubular shape is performed continuously.

Preferably, the step of closing an open portion of the strip S of filter material into a closed tubular shape is performed continuously.

Preferably, the step of pulling or dragging the strip S1 along the second feed direction T is performed continuously.

Preferably, the step of separating groups of one or more filter bags 1 is performed continuously.

Preferably, the step of separate groups of one or more filter bags 1 is performed along the second feed direction T. Advantageously, the first feed direction Z is vertical and the second feed direction T is horizontal. A machine and a method for making filter bags as described above fully achieve the preset aims with obvious advantages. More specifically, diverting the continuous strip of filter bags from the first feed direction to the second feed direction allows a safe and precise cutting of the filter bags, in the size required, that is to say, into groups of one, two or more filter bags partly separated by dashed pre-cutting lines. Moreover, diverting the continuous strip of filter bags from the first feed direction to the second feed direction simplifies stations and successive stacking steps.

Lastly, the continuous operation mode allows the productivity to be increased, maintaining a high quality of the filter bag.