ULTRASOUND DEVICE FOR SEALING AND CUTTING

Technical field

This invention relates to an ultrasound device for sealing and cutting, in particular for sealing and cutting material in sheets or strips for closing containers, for example for solid infusion or extraction products (filter bags, capsules and similar containers), or for liquid or gel products. Background art

In the technical field of sealing and cutting devices, the prior art teaches the use of ultrasound sealers and/or knives, which allow a precise processing of two materials superposed on each other, such as, for example, the sealing of edges of containers with strips of thermoplastic film and their corresponding separation from the continuous strips of the materials.

An ultrasound sealer or knife comprises a sonotrode which transmits mechanical vibrations to the material to be sealed and/or cut and a anvil which operates as a contact element for the material to be sealed and/or cut and the sonotrode.

In practice, the sonotrode transmits energy by contact with the material, which, by melting, is sealed and/or separated.

There are two types of ultrasound devices used for sealing and/or cutting operations:

- "heat-sinking" sealing devices, wherein the sonotrode is movable in an alternating manner along a single direction towards and away from the material to be sealed, and the anvil is stationary, or rotary; and

- rotary sealing devices, in which both the sonotrode and the anvil can be rotated, generally continuously, about mutually parallel axes of rotation. The sonotrode comprises an operating profile configured for sealing and/or cutting the superposed materials.

The anvil is equipped with one or more sections of contact surfaces correlated with the operating profile of the sonotrode (in some cases also one or more impressions shaped to match the operating profile of the sonotrode) to define the region to be sealed and/or cut of the superposed materials.

There are two operating solutions to perform the sealing and cutting of materials with these ultrasound devices, irrespective of the type of operating structure of the devices described above.

In a first embodiment, the sonotrode and the anvil are configured to perform the step of sealing and the step of cutting (separating) materials in strips or sheets in a single operation.

However, this first embodiment, due to high operating speeds, has drawbacks, since it is not possible to simultaneously guarantee sealing efficiency and cutting efficiency, with the result that the material is sometimes not sealed correctly, or not cut correctly.

Moreover, even at reduced operating speeds and in particular in machines with continuous movement, it is difficult to make sealing and cutting profiles for material of the type with a closed and complex perimeter.

This is a widespread problem for products in which the sealing and cutting finish has a significant commercial value.

In the second embodiment, the production systems or machines comprise two separate stations for sealing (by ultrasound) and separating (cutting or shearing) the material.

However, there are also drawbacks with this second embodiment.

In effect, passing from the sealing station to the cutting station, the sealed material can move relative to the feed line: this can result in the cutting of a part which is not sealed with consequent opening of the container. Aim of the invention

The aim of this invention is to provide an ultrasound device for sealing and cutting which overcomes the drawbacks described.

More specifically, the aim of this invention is to provide an ultrasound sealing and cutting device, in particular for sealing and cutting material in sheets or strips for closing containers, for example, solid infusion or extraction products, or liquid or gel products, which is able to perform the sealing and cutting operations in a single station in a fast, precise and safe manner.

A further aim of this invention is to provide an ultrasound sealing and cutting device, in particular for sealing and cutting material in sheets or strips for closing containers, which is capable of operating in any type of system or machine (in step or continuous mode), both at high and average-low production speeds and irrespective of the complexity of the profiles to be defined.

These aims are fully achieved by the ultrasound sealing and cutting device, in particular for sealing and cutting material in sheets or strips, for example, for closing containers for solid infusion or extraction products, or liquid or gel products, according to this invention as characterised in the appended claims.

More specifically, the ultrasound sealing and cutting device for sealing and cutting material in sheets or strips, advantageously for closing containers for solid infusion or extraction products, or liquid or gel products, comprises a sonotrode for emitting mechanical vibrations having a first profile and a contact body having a second profile acting in conjunction with the first profile of the sonotrode to define a sealing and cutting region. According to the invention, the first profile of the sonotrode or the second profile of the contact body comprises a first face and a second face joined together in a shared cutting edge.

According to the invention, the first face has a first angle of inclination relative to a plane in which it lies coincident with a portion of material in sheets or in strips passing in the sealing and cutting region.

Also according to the invention, the second face has a first angle of inclination relative to the plane in which it lies coincident with the portion of material in sheets or in strips passing in the sealing and cutting region. According to the invention, the first angle of the first face has a value different from the value of the second angle of the second face, so as to define an asymmetric profile.

Again according to the invention, at least the contact body has an impression on the edge of which, with a closed perimeter and protruding from the contact body, there is the second profile to delimit the closed sealing and cutting region in conjunction with the first profile of the sonotrode.

The different angles, therefore the asymmetry of the two faces forming the first or the second profile determine a different a function of the faces on the material to be processed.

Thanks to this architecture, it is therefore possible to perform a precise sealing and cutting on the material with a single sonotrode (and single contact body) precisely thanks to their geometrical structure which allows a simultaneous operational interaction on the material which is thus sealed and cut.

More specifically, it is possible to prevent the risk of cutting the material in zones not sealed, with consequent opening of the container. With the sealing and cutting device according to this invention it is therefore possible to make sealing zones of reduced width, with obvious advantages in terms of appearance of the container, because it is no longer necessary to extend the sealing zone to avoid cutting the material in zones not sealed.

Preferably, the first face and the second face define a cutting edge with a closed perimeter.

Preferably, the first profile and the second profile define a sealing and cutting region with a closed perimeter.

Advantageously, the first face defines an outer cutting surface in the sealing and cutting region and the second face defines an inner sealing surface in the sealing and cutting region. Alternatively, the first face defines an inner cutting surface in the sealing and cutting region and the second face defines an outer sealing surface in the sealing and cutting region.

Advantageously, the asymmetry of the two sealing and cutting faces allows a high output and precision irrespective of the shape of the end product.

The shapes to be sealed and cut may be of a linear type with a continuous and open profile.

The shapes to be sealed and cut may have a closed and complex perimeter profile (that is to say, geometrically complex shapes).

The complex shapes may be achieved with one or the other, or both, the first profile and the second profile lying on curved surfaces (for example, made on rotary drums, even continuously).

The asymmetric geometrical structure of the two faces forming the cutting edge can be adapted to any type of sealing and cutting device, such as devices with continuous, discontinuous or step movement, maintaining a high level of precision both for sealing and cutting the material, even at high operating speeds, allowing it to make small size seals without the risk of cutting material not sealed.

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 shows a schematic side view, with some parts cut away in order to better illustrate others, of an ultrasound device, according to this invention, for sealing and cutting, in particular for sealing and cutting material in sheets or strips for closing containers for solid, liquid or gel products;

- Figure 2 is a front view, with some parts cut away to better illustrate others, of the sealing and cutting device of Figure 1 ;

- Figure 3 shows a scaled-up detail A of a second profile of a contact body forming part of the sealing and cutting device of Figures 1 and 2;

- Figure 4 shows a schematic side view, with some parts cut away in order to better illustrate others, of a second embodiment of an ultrasound device, according to this invention, for sealing and cutting, in particular for sealing and cutting material in sheets or strips for closing containers for solid, liquid or gel products;

- Figure 5 shows a scaled-up detail B of the cutting and sealing device of Figure 4;

- Figure 6 shows the detail B in a further enlarged scale with some parts cut away to better illustrate others.

Detailed description of preferred embodiments of the invention

The accompanying drawings show a first embodiment of the ultrasound device for sealing and cutting according to this invention (denoted in its entirety by the numeral 100 in Figure 1 ) and a second embodiment of the ultrasound device for sealing and cutting according to this invention (denoted in its entirety by the numeral 200 in Figure 4), for sealing and cutting a material 1 in sheets or strips. Advantageously, the material 1 in sheets or strips may be used for enclosing a dose of solid, liquid or gel product for extraction or infusion or for closing containers 2 containing solid, liquid or gel products for infusion or extraction. Advantageously, the material 1 may also comprise one, two or more sheets or strips superposed.

For example, the material 1 in sheets or strips (preferably continuous) is fed towards the device 100, or 200, in such a way as to superpose a further strip (preferably continuous) defining a succession of containers 2 already filled with a dose of infusion or extraction product.

Alternatively, the material 1 in sheets or strips may be folded back on itself (to contain a dose of product), so that free edges of the material 1 are superposed, and such as to be sealed and cut.

The sealing and cutting device (100, 200) comprises a sonotrode 3 for emitting mechanical vibrations having a first profile 4 and a contact element 6, or anvil, having a second profile 12. The first profile 4 of the sonotrode 3 and the second profile 12 of the contact body 6 act in conjunction to define a sealing and cutting region 5.

In light of this, the material 1 in sheets or strips (preferably continuous) and the succession of containers 2 (preferably continuous) are fed between the sonotrode 2 and the contact body 3.

According to the invention, the first profile 4 of the sonotrode 3 or the second profile 12 of the contact body 6 comprises a first face 7 and a second face 8 joined together at a shared cutting edge 9. For example, the cutting edge 9 can form an edge or a vertex.

Also according to the invention, the first face 7 of the cutting edge 9 has a first angle a of inclination relative to a plane 10 in which it lies coincident with a portion of material 1 in sheets or in strips passing in the sealing and cutting region 5.

Also according to the invention, the second face 8 of the cutting edge 9 has a second angle β of inclination relative to the plane 10 in which it lies. Again according to the invention, the first angle a of the first face 7 has a value different from the value of the second angle β of the second face 8. Also according to the invention, at least the contact body 6 has an impression 11 on the edge of which, with a closed perimeter and protruding from the contact body 6 (that is, from its surface), there is the second profile 12 in such a way as to delimit the sealing and cutting region 5 in conjunction with the first profile 4 of the sonotrode 3.

The delimitation of the sealing region 5 is, therefore, delimited solely by the two profiles 4 and 12.

The term "impression" 11 means a hollow surface (or cavity) made (in this case) on the contact body 6 .

The cavity has an edge (outer) delimiting the perimeter shape of the impression 11 on which the second profile 12 of the contact body 6 is made.

It should be noted that the impression 11 of the contact body 6, having a defined depth, allows the housing of the container 2.

In light of this, the impression 11 of the contact body 6 extends (in depth) away from the plane 10 in which it lies.

It should also be noted that the second profile 12 is continuous, that is, without interruptions on its surfaces, along the entire extension of the edge of the impression.

In the first embodiment of Figures 1 to 3, the cutting edge 9 is made on the contact body 6. In the second embodiment of Figures 4 to 6, the cutting edge 9 is made on the sonotrode 3.

In other words, in the first embodiment of Figures 1 to 3, the second profile 12 of the contact body 6 defines the cutting edge 9. More specifically, the second profile 12 has an asymmetric shape defined by the various angles of inclination presented by the first and the second face 7 and 8 forming the cutting edge 9 (as clearly shown in Figure 3). The asymmetry between the two faces 7 and 8 is also shown clearly by the axis or straight line R passing through the cutting edge 9 shared between the two faces 7 and 8 and perpendicular to the plane 10 on which it lies. Thanks to this arrangement it is possible to optimise the various sealing and cutting operations as a function of the angles of inclination of the one face or of the other.

Preferably, the first profile 4 and the second profile 12 define a sealing and cutting region 5 with a closed perimeter.

Preferably, the first face 7 and the second 8 face define a cutting edge 9 with a closed perimeter.

In light of this, the first face 7 defines an outer cutting surface in the sealing and cutting region 5 and the second face 8 defines an inner sealing surface in the sealing and cutting region 5.

In alternative embodiments not illustrated, the first face 7 can define an inner cutting surface in the sealing and cutting region 5 and the second face 8 can define an outer sealing surface in the sealing and cutting region 5. In other words, the first face 7 and the second face 8 can be inverted. Again preferably, the first face 7 of the cutting edge 9 has the first angle a of inclination with a value of between 45° and 80° relative to the plane 10 in which it lies, preferably between 60° and 80°, and still more preferably between 60° and 75°.

Again preferably, the second face 8 of the cutting edge 9 has a second angle β of inclination with a value of between 0° and 45° relative to the plane 10 in which it lies, preferably between 0° and 30°, more preferably between 0° and 15°, and still more preferably between 15° and 30°.

A non-limiting example of an asymmetrical cutting edge 9 with the values of the angle between the values described above is clearly shown in Figure 3.

In other words, different angle values are used for the first face 7 and the second face 8 as a function of the sealing and cutting to be obtained.

More in detail, increasing the angle a of the first face 7 relative to the plane 10 in which it lies improves the cutting action of the material 1 ; on the contrary, reducing the angle β of the second face 8 relative to the plane 10 in which it lies improves the sealing action. The angles a and β can advantageously be selected as a function of the material.

Therefore, two faces 7 and 8 with different angles of the cutting edge 9 (thus generating an asymmetrical profile) relative to the plane 10 on which it lies have a different function given by the value of the angle: preferably, the face with a smaller angle for sealing and the face with a larger angle for cutting.

It should be noted that the ultrasound sealing and cutting device 100 (or 200) comprises, in cascade, an electrical power signals generator 17; a converter 18 for converting the electrical power signals into mechanical vibrations; the sonotrode 3 comprising an operating head which has the first profile 4; and the contact body 6 (or anvil) of the second profile 12. In the first embodiment 100, the first profile 4 of the sonotrode 3 has at least one relative stretch with a flat extension, that is to say, parallel to the plane 10 on which it lies.

Advantageously, the first profile 4 of the sonotrode 3 has a flat extension (to define a flat contact head, as shown in Figures 1 and 2).

In an alternative embodiment, the first profile 4 of the sonotrode 3 has a curved extension, for example cylindrical, to match the contact body 6. Advantageously, the sonotrode 3 has a counter-impression 1 1 a having a perimeter edge closed and protruding relative to a base surface of the impression 1 a.

On the edge of the counter-impression 1 1a there is the first profile 4 of the sonotrode 3 shaped to match the edge of the impression 11 of the contact body 6 (see dashed line in Figures 1 and 2).

This structure of the device 100, in its different modes for feeding the material 1 in sheets or strips and of the containers 2 (continuous to step mode), is illustrated in Figures 1 , 2 and 3.

Again with reference to Figures 1 , 2 and 3, preferably the contact body 6 has at least one impression 1 1 with a closed perimeter consisting of the second asymmetrical profile 12 comprising the first face 7, the second face 8 joined together in the shared cutting edge 9.

Preferably, the contact body 6 has at least one impression 1 1 equipped with the second asymmetrical profile 12 and with curved extension.

In light of this, the contact body 6 has the at least one impression 1 1 delimited by the second profile 12 made on the protruding edge of the impression 1 1.

Again, preferably, the protruding edge of the impression 1 1 has a curved extension.

In other words, the curved edge extends along a surface of the contact body 6 according to a path away from and towards the plane 10 in which it lies.

Thanks to this feature it is possible to adapt the shapes of the impressions 11 and hence the second profiles 12 (in this case asymmetrical) to a multiplicity of types of contact bodies 6.

Preferably, the contact body 6 comprises a drum 14 rotating continuously, or in step mode, about an axis of rotation X, for example perpendicular to a feed direction of the material 1 in strips or sheet (Figures 1 and 2).

Preferably, the drum 14 has a cylindrical surface on which there are a plurality of impressions 11 , defined by the second asymmetrical profile 12 with curved extension. Advantageously, the impressions 11 are evenly distributed on the cylindrical surface of the drum 14.

In the embodiment illustrated in Figures 1 and 2, the drum 14 is rotatable, preferably continuously, about the axis X, whilst the sonotrode 3, during operation, is stationary. The sealing and cutting device 100 comprises suitable actuators 19 to move the sonotrode 3 to an operating position close to the material 1 to be sealed and cut and a non-operating position away from the material 1 to be sealed and cut.

In a variant embodiment of the first or second profile 4 or 12, the second face 8 has a first part perpendicular to the plane 10 in which it lies and a second part parallel to the plane 10 in which it lies in such a way as to form an undercut or a broken line.

In light of this, the second face 8 has at least its second part parallel to the plane 10 on which it lies (0° inclination) defining a sealing area.

It should be noted that the first part of the second face 8 is for fitting between the first face 7 and the actual respective sealing area.

Figures 4 to 6 show a second preferred embodiment of the ultrasound device 200 for sealing and cutting, wherein the first profile 4 is made according to the variant embodiment described above. More specifically, the second face 8 of the first profile 4 has a first part perpendicular to the plane 10 in which it lies and a second part parallel to the plane 10 in which it lies and the second profile 12 made on the contact body 6 (or anvil) is asymmetrical and shaped to match the first asymmetrical profile 4.

It should be noted that the ultrasound sealing and cutting device 200 (illustrated in Figures 4 to 6) operating in step mode, but comprises the technical features of the structure described above with regard to the sonotrode 3.

The device 200 illustrated in Figure 4 has a contact body 6 which comprises a die 15 having a contact head 16 shaped to match the operating head of the sonotrode 3.

Preferably, the contact head 16 defines the impression 11 with the projecting perimeter edge on which the second profile 12 is made.

On the contact head 16, that is to say, on the edge, there is the second profile 12 which has a contact face 13 designed to couple with the second face 8 (for sealing) of the first profile 4. In other words, the contact face 13 may comprise at least one section inclined by an angle complementary to the angle β, to couple with the second face 8.

Alternatively, the second profile 12 may have at least a plane parallel to the plane 10 on which it lies.

Advantageously, the second profile 2 comprises a contact face 13 having its plane parallel to the plane 10 in which it lies and a relative further surface configured, in use, for coupling to the perpendicular part of the second face 8 (Figure 5), that is, perpendicular to the plane 10 in which it lies.

In light of this, the second profile 12 comprises a further contact face 13a

(outside the impression 1 ) for the contact with the cutting edge 9.

The further face 3a is parallel with the plane 10 on which it lies.

In other words, the combination of first profile 4 and second profile 12 determines a corresponding undercut shape for sealing on the planes (internal) parallel to the plane 10 in which it lies, whilst the cutting edge 9 and the second face 7 implement cutting and run up to the contact point, of the cutting edge 9, with the further face 13a of the second profile 12. This particular geometrical shape of the two profiles allows a precise sealing due to the opposite planes of the two surfaces of the two profiles which correctly hold the portion of material to be sealed. The two surfaces perpendicular to the plane in which it lies allow, on the other hand, the tensioning and cutting in a precise manner and without waste or incorrect relative movements of the film 1 and the container 2 being processed. Advantageously, in an embodiment not illustrated, the second profile 12 of the contact body 6 has a flat extension, parallel to the plane 10 in which it lies (to define a flat contact head), which acts in conjunction with the cutting edge 9.

The second profile 12 may have closed perimeter extension.

The die 15 is movable axially between an operating position, close to the sonotrode 3, and a non-operating position, away from the sonotrode 3. The sealing and cutting device 200 comprises suitable actuators 19 to move the sonotrode 3 between an operating position close to the material 1 to be sealed and cut and a non-operating position away from the material 1 to be sealed and cut. The sealing and cutting device 200 also comprises actuators 20 for moving the die 5.

The double coordinated movement of sonotrode 3 and die 15 towards and away from each other makes it possible to feed, for example, deep containers (see also Figure 5).

Thanks to the asymmetry of the cutting edge 9, the ultrasound sealing and cutting of material in sheets or strips has a high output and precision irrespective of the shape of the end product.

The asymmetric combination of the first face and the second face of the cutting edge allows high quality sealing and cutting both in the case of linear shapes with a continuous and open profile and in the case that containers must be closed and separated with perimeter shapes having a closed and complex profile (that is to say, complex geometrical shapes), if necessary made using curved profile impressions on rotary drums, even operating continuously.

Moreover, the cutting edge may be made alternatively on the sonotrode or on the contact body, that is to say, on the first profile or on the second profile, and can interact with a flat surface, or shaped in a complementary, or partly complementary manner.

The sealing and cutting device structured in this way can be adapted to any type of machine, with continuous, discontinuous or step mode movement, maintaining a high level of precision in the sealing and in the cutting of the material and irrespective of the operational speeds required.