Patent Description:
The filter bags according to the invention may be of the so-called traditional type, that is to say, single-lobed or double-lobed filter bags (that is, with a flat extension) or also the pyramidal filter bags (that is, with a substantially three-dimensional extension).

Both types of filter bags have as common elements, as well as a piece of filter material paper and a dose of infusion product, a stretch of thread which is joined, on one side, to the piece of filter material and, on the other side, to a gripping tag.

The thread is usually positioned around the filter bag according to a predetermined path and associated with the filter bag with joining points (for example by sealing) of a differentiated type: strong points if the join must be maintained even during use or light points if that part of the thread has to be detached before use.

The machines for forming this type of filter bag may comprise in a prior art solution of the example type and as the base structure:.

As already mentioned, in the current machines for forming the above-mentioned filter bags stations are used for forming the above-mentioned joining points and stations for sealing and cutting the filter bag formed with ultrasound devices.

In particular, the ultrasonic device used for sealing and cutting the filter bags formed is positioned downstream of the line for forming the filter bags and allows the simultaneous closing of the top of a filter bag formed and the bottom of a filter bag being positioned upstream of the previous filter bag relative to a feed direction of the strip of filter material.

The sealing and cutting device comprises:.

In this solution, the sonotrode has a C-shaped cross-section to define, on one side, the sealing of the top of a filter bag already provided with the dose of product and, on the other hand, the bottom of a next filter bag to be formed.

The groove present in the centre of the sonotrode allows the insertion of the knife during the step of cutting the strip of filter material, that is, the two filter bags being formed, with a scissor-like action.

This type of structure of a sealing and cutting device is known from document <CIT> and <CIT>.

However, this technical solution has some drawbacks.

The combination between a linear knife and the groove of the sonotrode to perform a sort of scissor cut causes rapid wear of the cutting part of the knife.

The wear of the knife also increases further due to the high elasticity of some materials used in the formation of filter bags, in particular the so-called "woven - non-oven" materials.

To this must be added the fact that, in order to obtain a precise and good quality cut with this solution, it is necessary to deactivate the sonotrode during the cutting step to prevent the vibrations from determining an incorrect cutting line. This requires an overall slowing down of the steps and a greater stress of the components of the sonotrode.

The aim of this invention is to provide a sealing and cutting device for forming filter bags with infusion products, such as, for example, tea, coffee, camomile and the like, which overcomes the above-mentioned drawbacks.

In particular, the aim of the invention is to provide a sealing and cutting device for forming filter bags with infusion products, such as, for example, tea, coffee, camomile and the like, which is able to improve the final quality of the filter bags.

A further aim of the invention is to provide a sealing and cutting device for forming filter bags with infusion products, such as, for example, tea, coffee, camomile and the like, which is able to increase the operating life of the components forming the device and, at the same time, reduce the times for forming the filter bags.

Said aims are fully achieved by the devices and methods for sealing and cutting bags containing products, especially filter bags with infusion products, such as, for example, tea, coffee, chamomile and the like, according to this invention as characterised in the appended claims.

The technical 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:.

With reference to the accompanying drawings, and in particular to <FIG> and <FIG>, the device according to the invention, labelled <NUM> in its entirety, is used for sealing (by ultrasound) and cutting so as to form bags containing products of different types.

In the case illustrated, purely by way of a non-limiting example, the formation of filter bags for infusion products is described.

Therefore, again by way of example, the sealing and cutting device <NUM> may be used on machines (not illustrated) for forming filter bags configured to form both the three-dimensional filter bags such as the pyramid bags and the so-called traditional single-lobed or double-lobed bags with a rectangular shape.

Each bag is obtained with a piece of material containing at least one dose of product. In the case of filter bags, each filter bag is obtained with a piece of filter material containing a dose of infusion product.

Described below is the bag to be joined and cut from by device according to the invention, such as a filter bag obtained with filter material, but the solution according to the invention may be applied any other type of bag containing a product without limiting the scope of the solution.

The sealing and cutting device <NUM> comprises a sealing head <NUM> or sonotrode configured for sealing a portion <NUM> of a continuous tubular strip <NUM> of filter material (illustrated with a dashed line in <FIG> and <FIG>), feeding along a feed direction D2 (in such a way as to define a closed head of a first filter bag already provided with a dose of product and the bottom of a second filter bag being formed upstream of the first relative to the feed direction D2).

The direction of feed of the strip <NUM> may be along a vertical plane, a horizontal plane or an inclined plane depending on the type of forming machine on which the device <NUM> is applied.

The sealing and cutting device <NUM> comprises a counterhead or anvil <NUM> positioned facing the sonotrode <NUM>.

The anvil <NUM> has a box-shaped structure with a length (or main longitudinal extension) at least equal to or greater than the length of the sonotrode <NUM>.

The sealing and cutting device <NUM> comprises a movement system <NUM> connected to the sonotrode <NUM> and/or to the anvil <NUM> and configured for moving the sonotrode <NUM> and the anvil <NUM> (in a synchronised fashion) between a first non-operating position, wherein the sonotrode <NUM> and the anvil <NUM> are spaced apart, and a second operating position wherein the sonotrode <NUM> and the anvil <NUM> are in front contact for sealing the portion <NUM> of the strip of filter material, in such a way as to form a simultaneous sealing of a top and bottom of respective bags to be formed.

The sonotrode <NUM> and the anvil <NUM> are moved in a synchronised fashion along a direction D3 of movement transversal to the feed direction D2 of the continuous strip <NUM> of filter material.

The movement system <NUM> (connected to the sonotrode <NUM>) comprises a plurality of kinematic mechanisms (such as pairs of connecting rods and cranks and relative drive units) which are able to synchronise the movement towards and away from the sonotrode <NUM> and the anvil <NUM>.

The sealing and cutting device <NUM> comprises a cutting element <NUM> comprising a circular blade <NUM> connected to a supporting and movement element <NUM> which is able to impart a translational movement to the blade <NUM> with a circular shape along a direction D6 perpendicular to the feed direction D2 of the continuous tubular strip <NUM>.

It should be noted that the cutting element <NUM> is positioned on the anvil <NUM> and configured to cut the strip <NUM> of filter material, with the sonotrode <NUM> and the anvil <NUM> in the second operating position, in such a way as to separate the first filter bag formed from the remaining continuous strip <NUM> of filter material.

As illustrated also in <FIG>, the anvil <NUM> comprises a slit <NUM> from which the blade <NUM> protrudes, which is configured for cutting the tubular strip <NUM>, by contact with the sonotrode <NUM>, whilst the sonotrode <NUM> and the anvil <NUM> are in the second operating position, in such a way as to separate a bag formed from the remaining continuous strip <NUM>.

According to a first embodiment, the cutting element <NUM> comprises a wheel 6a with a circular blade profile <NUM> articulated, and freely rotatable, with the movement and support unit <NUM> positioned inside the anvil <NUM>.

According to a second embedment, the cutting element <NUM> comprises a wheel 6a with a circular blade profile <NUM> associated rigidly with the movement and support unit <NUM> positioned inside the anvil <NUM>.

According to a third embodiment, the cutting element <NUM> comprises a wheel 6a with a circular blade profile <NUM> articulated with the movement and support unit <NUM> positioned inside the anvil <NUM>.

In light of this, the wheel 6a is connected to an independent movement unit <NUM> configured to impart the forced rotation to the wheel 6a, at least during the translation movement of the blade <NUM> (irrespective of the contrast with the sonotrode <NUM>).

The independent unit <NUM> is illustrated with a block in <FIG> and may consist of a drive unit or a kinematic coupling with a pinion-rack unit which is able to rotate the wheel <NUM> when the movement and support means <NUM> are activated.

Preferably, the movement and support unit <NUM> comprises a body <NUM> for supporting the wheel 6a connected to an actuator <NUM> configured for moving, in both directions, the supporting body <NUM> along the longitudinal extension of the anvil <NUM>.

In light of this, the supporting body <NUM> is slidably connected to a linear guide <NUM> positioned inside the anvil <NUM> in such a way as to allow a rectilinear stroke of translation in both directions of the wheel 6a.

Preferably, the supporting body <NUM> comprises a rocker <NUM> articulated in its central part to the supporting body <NUM>.

The rocker <NUM> has a first arm <NUM> and a second arm <NUM>.

The wheel 6a is articulated on the first arm <NUM> (on the free end of the first arm <NUM>). A grub screw <NUM> for adjusting and counter-balancing in contact with the supporting body <NUM> is screwably connected on the second arm <NUM> in such a way as to adjust the operating position of the wheel 6a protruding from the slit <NUM>.

In light of this, an elastic preloading element <NUM> (a spring) is interposed between the supporting element <NUM> (the supporting body <NUM>) and the blade <NUM> (the first arm <NUM>) and is able to keep the blade <NUM> in contact with the sonotrode <NUM> in the second operating position.

As illustrated, the sonotrode <NUM> comprises a contact surface <NUM>, facing the anvil <NUM> with a flat and continuous profile on which the blade <NUM> with a circular profile can slide in such a way as to determine a cut of the tubular strip <NUM> of filter material by making contact with the contact surface <NUM>.

Preferably, the anvil <NUM> has the slit <NUM> with a length S7 at least equal to the length S1 of the sonotrode <NUM> in the sealing zone (preferably, the slit <NUM> may have an extension greater than the extension of the sonotrode <NUM>).

Preferably, the anvil <NUM> is made as a single piece.

Preferably, the sonotrode <NUM> and/or the blade <NUM> are made of hardened materials. The invention also provides a method for sealing and cutting bags (filter) containing infusion products.

As illustrated, the cutting step is performed by the blade <NUM> by contact on the sonotrode <NUM>.

It should also be noted that the cutting step comprises a translation of the cutting element <NUM> with the blade <NUM> having a circular shape along a direction D6 perpendicular to the direction D3 of movement of the sonotrode <NUM> and the anvil <NUM>.

It should be noted that the translation of the cutting element <NUM> occurs along the entire longitudinal extension of the sonotrode <NUM> and the anvil <NUM> to allow a secure and complete separation of the filter bag formed relative to the remaining strip of filter material.

Preferably, during the cutting step by the cutting element <NUM> with the blade <NUM> with a circular shape occurs during the sealing step of the activated sonotrode <NUM>.

The preset aims with numerous advantages are achieved thanks to a machine structured in this way.

The presence of a circular blade (preferably rotating) makes it possible to increase the working life of the blade.

The presence of a flat sonotrode which defines a surface for contact with the circular blade increases the safety and precision of cutting the stretch of strip of filter material.

Claim 1:
A sealing and cutting device for forming bags containing products; the sealing and cutting device (<NUM>) comprising:
- a sealing head (<NUM>) or sonotrode configured for sealing a portion (<NUM>) of a continuous tubular strip (<NUM>) of filter material, feeding along a feed direction (D2);
- a counterhead or anvil (<NUM>) positioned facing the sonotrode (<NUM>);
- a movement system (<NUM>) connected to the sonotrode (<NUM>) and/or to the anvil (<NUM>) and configured for moving the sonotrode (<NUM>) and/or the anvil (<NUM>) between a first non-operating position, wherein the sonotrode (<NUM>) and the anvil (<NUM>) are spaced apart from each other, and a second operating position wherein the sonotrode (<NUM>) and the anvil (<NUM>) are in front contact for sealing the portion (<NUM>) of the continous tubular strip of filter material in such a way as to simultaneously seal a head and a bottom of respective bags to be formed;
- a cutting element (<NUM>) comprising a circular blade (<NUM>) connected to a supporting and movement unit (<NUM>) which is able to impart a translational movement to the blade (<NUM>) with a circular shape along a direction (D6) perpendicular to the feed direction (D2) of the continuous tubular strip (<NUM>) of filter material, the anvil (<NUM>) comprising a slit (<NUM>) from which the blade (<NUM>) protrudes, characterised in that the blade (<NUM>) is configured to cut the continous tubular strip (<NUM>) of filter material, by contact with the sonotrode (<NUM>), whilst the sonotrode (<NUM>) and the anvil (<NUM>) are in the second operating position, from the remaining strip in the second operating manner, so as to separate a bag formed from the remaining continuous tubular strip (<NUM>) of filter material.