CN111770882A

CN111770882A - Device for filling a container with a metered quantity of powdered material

Info

Publication number: CN111770882A
Application number: CN201980014551.4A
Authority: CN
Inventors: 桑德罗·纳尔迪
Original assignee: Normaico Co Co ltd
Current assignee: Normaico Co Co ltd
Priority date: 2018-02-23
Filing date: 2019-02-22
Publication date: 2020-10-13
Anticipated expiration: 2039-02-22
Also published as: WO2019162980A1; IT201800003007A1; EP3755629A1; CN111770882B; EP3755629B1; ES2907110T3

Abstract

An apparatus for filling containers with metered amounts of powdered material, the apparatus comprising a metering wheel (2) rotatable about a substantially horizontal axis of rotation (a), the metering wheel (2) comprising a plurality of channels (5) extending in respective radial directions from an outer peripheral edge (6) of the metering wheel (2) towards a centre of the metering wheel (2); a hopper (3) arranged above the metering wheel (2) and adapted to contain the powdery material; a plurality of pistons (9) slidably inserted inside the channels (5), respectively, each piston (9) comprising a stem (11) and a head (12) integral with one end of the stem (11), each piston (9) defining a calibration chamber (10) in the channel (5) arranged to collect a metered quantity of the powdery material. Each calibration chamber (10) is delimited by the head (12) of the piston (9) concerned and by the inner wall of the respective channel (5).

Description

Device for filling a container with a metered quantity of powdered material

Technical Field

The invention relates to a device for filling a container with a metered amount of powdered material.

Background

The need to automatically fill a particular container, such as a bottle or the like, with a predetermined amount of powdered material has been known for some time.

Therefore, apparatuses have been developed which allow the introduction of metered quantities of powdered material into relative containers which are conveyed continuously along a feed line.

According to a known type, these devices comprise a metering wheel rotating about a substantially horizontal rotation axis. The metering wheel is located below a hopper containing the powdered material to be introduced into the container. The metering wheel has a series of channels formed in the peripheral portion of the wheel itself; in each channel a piston is inserted which is adapted to delimit a collection chamber of the powdered material. Each chamber is associated with suction means suitable for creating a vacuum condition in the chamber, so as to suck a predetermined quantity of powdered material from a hopper inside the chamber when said chamber occupies an operating position near the hopper. In each chamber, a fluid, such as compressed air, is introduced through conduction means to unload the quantity of powdered material from the chamber to the respective container.

Patent US 3,656,518 discloses an apparatus for filling containers with powdered material, comprising a metering wheel rotatably mounted on a rotating shaft carried by a supporting frame. A hopper containing powdered material is placed over the metering wheel. The metering wheel has a plurality of openings extending in a radial direction from the outer periphery of the wheel itself to the center of the wheel itself. In each opening, a sleeve is inserted in which a piston comprising a stem and a head is slidably arranged; the piston head is made of a material that is permeable to the gaseous state but impermeable to the powdered material. The piston head delimits in the sleeve a metering chamber suitable for collecting a predetermined quantity of powdered material. The rod of each piston defines, at one end, a cam follower arranged in contact with a cam device adapted to drive the piston in translation inside the sleeve. Each metering chamber is provided with a lateral opening communicating with a support element associated with the rear of the wheel. The support element forms an arc-shaped channel extending along a circumferential arc comprised between a loading position of the material and an unloading position of the material, and performs the function of allowing the retention of the powdered material into the chamber. The lateral openings and the channels of the support element are connected to a vacuum pump adapted to generate a vacuum condition in each chamber and in the channels, in order to respectively suck the powdered material from the hopper when the chambers are placed at the same height as the hopper, and in order to allow the material to be kept in the same chamber during the rotation of the metering wheel to the unloading position.

A further device of this type is shown in patent EP 202868.

An apparatus for filling a container with a powdery material is also described in patent US 4,567,714. The apparatus comprises at least one device configured to dispense a metered amount of material and arranged below a hopper containing the material to be dispensed. Each device comprises a fixed inner element and an outer element arranged concentrically with respect to the inner element. The outer element forms a rotatable ring comprising a plurality of radially extending openings adapted to receive an associated piston sliding within the openings. One end of each piston is coupled with a channel that drives the movement of the piston in the radial direction within the associated opening, at least for a portion of the circumference of the ring, during the rotation of the outer ring relative to the central element.

A particular field of use of these devices is the pharmaceutical field. In this field, it is considered necessary to automatically fill small containers with metered quantities of pharmaceutical powdered product, ensuring a high precision and repeatability of the product dosing operations.

In particular, in the field of powdered pharmaceutical products such as powders for injectable solutions described above, solutions have been adopted in which the container is filled only with the active agent excluding the excipients, in order to better control the dose of the active ingredient.

On the one hand, this solution allows a better control to be exercised over the quantity of material corresponding to the unit dose of product to be inserted in the respective container, but on the other hand, in the case of a mixture comprising active ingredients and excipients, it determines the problem of managing a very small quantity of powdered product, which is less than the quantity of product that has been processed. Known apparatuses for filling containers have size and structural limitations which make it difficult to manage very small quantities of powdered product.

Another problem to be considered is the need to always meet the precision and repeatability requirements of dosing operations, which are particularly stringent in the pharmaceutical field.

Disclosure of Invention

The object of the present invention is to solve the above problems by devising a device that allows to automatically fill a container with a metered amount, even a very small dose, of powdered material.

Another object of the present invention is to provide an apparatus that allows to perform the dosing and filling operations of containers with high precision and repeatability.

It is another object of the invention to provide a structurally robust device.

Another object of the present invention is to provide a device for filling containers with a powdered material of simple construction and functional concept, which is absolutely functionally reliable, versatile in use and relatively inexpensive.

According to the invention, the above object is achieved by an apparatus for filling a container with a metered amount of powdered material according to claim 1.

An apparatus for filling a container with a metered amount of powdered material, the apparatus comprising a metering wheel rotatable about a substantially horizontal axis of rotation, the metering wheel comprising a plurality of channels extending in respective radial directions from a peripheral edge of the metering wheel towards a centre of the metering wheel; a hopper disposed above the metering wheel and adapted to contain the powdered material; a plurality of pistons respectively slidably inserted inside said channels, each piston comprising a rod and a head integral with one end of said rod, each piston defining in said channel a calibration chamber arranged to collect a metered quantity of said powdery material, said calibration chamber being delimited by the head of the piston concerned and by the inner wall of the respective channel; an adjustment assembly associated with the metering wheel, the adjustment assembly allowing for the position of each piston inside the respective channel to be adapted to be adjusted; -conducting means in communication with said channels and adapted to be alternately connected to a negative pressure source and to a positive pressure source, so as to respectively create a vacuum condition in each of said calibration chambers and so as to introduce a fluid flow inside said calibration chambers, said head of each of said pistons presenting the following cross section: the cross-section has a diameter smaller than a diameter of a cross-section of an end portion of the stem, the end portion being opposite the head.

It can be seen that the provision of the piston with a head having a smaller cross section than the end portion of the rod allows, for each channel, to obtain a base surface of the calibration chamber having a reduced extension and therefore a range of volume values of the chamber which is smaller than the range of volume values obtainable by known devices of the same type.

The metering wheel comprises a disc-shaped body inside which said channels are formed, each of said channels having an opening at said peripheral edge, said openings putting the disc-shaped body in communication with the external environment.

Each of the channels has a cross-section that increases from the peripheral edge toward a center of the disc-shaped body. Thus, due to the configuration of the channels themselves, the assembly of the pistons in the channels becomes easy, which allows each piston to be inserted from the centre of the disc-like body inside the relative channel.

Preferably, the diameter of the cross-section of the head of each said piston has a value in the range of about 3.5mm to 4 mm.

Preferably, the diameter of the cross section of the head has a value of about 4 mm.

Preferably, the head comprises a filtering element provided with a plurality of holes able to ensure the permeability of the head to gaseous media and the impermeability of the head to the powdered material.

Preferably, the diameter of the end portion of the rod has a value of about 5 mm.

Preferably, said channels are regularly distributed on said disc-shaped body.

Preferably, the channels are arranged at the same angular distance with respect to each other.

Advantageously, each of said channels comprises a section near a central portion of said disc-shaped body, said section being configured to allow insertion of the relative piston during assembly.

Preferably, said section near the central portion of the disc-shaped body has a larger cross section with respect to the section of the end portion of the piston.

Preferably, each of said channels comprises an end section on the side of said peripheral edge, said end section having a cross-section with a diameter substantially corresponding to the diameter of the cross-section of the head of the associated piston, unless play is present.

Preferably, the adjustment assembly comprises a plurality of actuating elements connected to respective pistons.

Preferably, the actuating element is made of a pin.

Preferably, each pin is inserted into a corresponding hole made in the end portion of the associated piston.

Preferably, said actuating element is constrained to an adjusting ring and to an associated sliding guide.

Preferably, said adjusting ring is associated frontally with the disc-shaped body and occupies a substantially central portion of the disc-shaped body. Preferably, the adjustment ring includes a series of grooves defining a series of spirals extending from a center to an outer periphery. Preferably, the helix is an archimedean helix.

Preferably, said adjustment assembly comprises a series of said sliding guides, one for each actuation element, said guides extending in a respective radial direction of the disc-shaped body.

Advantageously, the adjusting ring may be driven in rotation about the substantially horizontal axis to simultaneously move the actuating elements in a radial direction inside the relative sliding guides so as to translate the corresponding pistons along the relative channels.

Preferably, the conducting means comprises a plurality of conduits, one for each said channel.

Preferably, said ducts are at a predetermined inclination angle with respect to the respective channel having a value less than 90 °.

Preferably, the inclination angle has a value of about 50 °. It has been experimentally observed that the arrangement of each conduit with an inclination angle exhibiting the above values is advantageous in terms of fluid-dynamic properties. In particular, a reduction of the turbulence phenomenon is observed from the experimental results and this contributes to making the device more precise and provided with high repeatability.

Preferably, said inclination angle refers to the angle comprised between the median longitudinal axis of each duct and the median longitudinal axis of the relative channel.

Preferably, the conduits extend from the respective channels to the rear surface of the metering wheel.

Preferably, a distributor element is associated with the rear surface of said disc-shaped body and occupies a fixed position during the rotation of the disc, said distributor element being suitable for being connected to said positive pressure source or to said negative pressure source.

Preferably, in certain operating steps of the metering wheel, said conduit is put in communication with said distributor element.

Drawings

The details of the invention will become more apparent from the detailed description of a preferred embodiment of an apparatus for filling containers with metered quantities of powdered material, according to the invention, which is illustrated by way of example in the accompanying drawings, wherein:

fig. 1 shows a front view of an apparatus for filling a container with a metered amount of powdered material according to the invention;

FIG. 2 shows a front view of a detail of the present apparatus;

FIG. 3 shows an enlarged cross-sectional view of the above-mentioned details in the plane according to line III-III of FIG. 2;

figure 4 shows a front view of another detail of the device according to the invention;

figures 5 and 6 show a rear front view and a section view, respectively, of the plane according to line VI-VI of the detail shown in figure 4;

FIG. 7 shows an enlarged front view of the detail shown in FIG. 4;

FIG. 8 shows a front view of another detail of the apparatus;

fig. 9 and 10 show a front view and a top view of a further detail of the device.

Detailed Description

With particular reference to these figures, an apparatus for filling containers with metered amounts of powdered material according to the present invention is generally indicated at 1.

It is specified in the following disclosure that the term "about" refers to a range of values around the indicated value, taking into account tolerances foreseen in the technical field.

The apparatus 1 comprises a metering wheel 2, which metering wheel 2 is arranged to meter a predetermined amount of powdered material, such as a pharmaceutical product, and to fill a series of containers with such metered amounts of powdered material.

Preferably, the container is a special bottle.

The powdered material is inserted inside a hopper 3, said hopper 3 being arranged above the metering wheel 2. The hopper 3 is fed by a specific tank, not shown, in which the powdered material is arranged. The hopper 3 may comprise mixing means capable of ensuring continuous mixing of the materials.

The containers to be filled are arranged in succession along a feed line, which may comprise a conveyor belt adapted to define an operating surface on which the containers rest.

The conveyor belt takes the containers to the metering wheel 2. In particular, the conveyor belt comprises at least one section extending below the metering wheel 2 in order to carry out the filling operation.

If the powdered material is a pharmaceutical product, the device 1 is installed inside an aseptic chamber characterized by the following environmental parameters: such as the composition, temperature, pressure and humidity of the air with values that decrease within predetermined intervals. The sterile room provides an efficient filtration system, such as a HEPA filter, adapted to ensure the maintenance of a sufficient level of air cleanliness within the room.

The metering wheel 2 is rotatably supported by a shaft associated with a support frame, not shown in the figures. More precisely, the metering wheel 2 is driven in rotation about a substantially horizontal axis of rotation a by a motor element, not shown. Preferably, the metering wheel 2 is driven to rotate in an intermittent motion.

The metering wheel 2 comprises a disc-shaped body 4, the disc-shaped body 4 being provided with a plurality of channels 5 extending in respective radial directions from an outer peripheral edge 6 towards the centre of the disc-shaped body 4. The channels 5 are regularly distributed on the disc-shaped body 4 and are arranged at the same angular distance with respect to each other.

Each channel 5 is formed inside the disc-shaped body 4 and each channel 5 has, at its end corresponding to the peripheral edge 6, an opening 7, which opening 7 puts the channel 5 in communication with the external environment.

The diameter of the cross section of each channel 5 varies in the radial direction and increases from the peripheral edge 6 towards the centre. In particular, each channel 5 comprises, on the side of the peripheral edge 6, an end section 8, the end section 8 presenting a cross-section with a diameter d0 substantially corresponding to the diameter d4 of the cross-section of the head of the piston inserted in the end section 8, unless play is present, as better explained below.

Instead, the section of each channel 5 arranged near the central portion C of the disc-shaped body 4 is configured to allow the insertion of the relative piston during assembly. More specifically, the section near the central portion C of the disc-shaped body 4 has a cross section that is greater with respect to the section of the end portion of the piston.

A piston 9 is slidably inserted inside each channel 5, said piston 9 being adapted to define a calibration chamber 10, said calibration chamber 10 being arranged to collect a predetermined quantity of powdered material.

Each piston 9 comprises a rod 11 and a head 12 integral with the end of the rod 11. In the mounted configuration, the stem 11 extends as part of the channel 5 and the head 12 faces the peripheral edge 6.

The head 12 preferably has a hollow cylindrical shape, and the head 12 includes a filter element 13 mounted on a base surface.

The filter element 13 comprises a plurality of holes 14 of predetermined dimensions so as to ensure permeability to gaseous media and impermeability to powdered materials.

The stem 11 has a cross-section that decreases from one end opposite the head 12 to the end integral with the head 12. More precisely, the stem 11 forms a first end portion 15 opposite the end where the head 12 is arranged, and the stem 11 forms a second intermediate portion 16 adjacent to the end portion 15, the second intermediate portion 16 having a first narrowing cross section. The diameter d2 of the intermediate portion 16 is smaller than the diameter d1 of the end portion 15.

The stem 11 forms a third portion 17 adjacent to the intermediate portion 16, which has a further narrowed cross-section with a diameter d3 smaller than the diameter d 2. The head 12 of the piston 9 is integrally associated with the third portion of the stem 11.

The diameter d4 of the cross-section of the head 12 is smaller than the diameter d1 of the cross-section of the end portion 15 of the stem 11. Preferably, the diameter d4 of the cross-section of head 12 has a value in the range of about 3.5mm to 4 mm. Even more preferably, the diameter d4 of the cross-section of the head 12 has a value of about 4 mm.

Preferably, the diameter d1 of the end portion 15 of the rod 11 has a value of about 5 mm.

Each calibration chamber 10 is delimited by the inner wall of the respective channel 5, in particular by the end section 8 of the channel 5 and by the base surface of the head 12 of the piston 9.

Experimental testing has shown that by providing a piston with a head 12 having a diameter of about 4mm, and taking into account that the material has a 0.55g/cm³The calibration chamber 10 can contain an amount of powdered material within a range of values between a minimum of 20mg and a maximum of 60mg, depending on the specific gravity.

The range of values of the amount of material contained in the chamber corresponds to the following ranges: within which the volume of the calibration chamber 10 can be varied.

The adjustment of the volume of the chamber 10 is carried out by adjusting the position occupied by the piston 9 in the channel 5. The sliding of the pistons 9 in the respective channels 5 is operated by an adjustment assembly 18 associated with the metering wheel 2.

The adjustment assembly 18 comprises a plurality of actuating elements 19 connected to the respective pistons 9.

Each piston 9 forms a hole 20 in the end portion 15, through which hole 20 a respective actuating element 19 is inserted. Preferably, the actuating element is constituted by a pin 19. The pin 19 is constrained to an adjusting ring 21 and to an associated guide 22.

The adjusting ring 21 is associated frontally with the disc-shaped body 4, and the adjusting ring 21 occupies a substantially central portion of the disc-shaped body 4. The adjustment ring 21 includes a series of grooves 23 that define a series of spirals extending from the center to the outer periphery. Helix 23 is an archimedean helix.

The adjustment assembly 18 provides a plurality of sliding guides 22 extending in respective radial directions of the disc-shaped body 4, one guide 22 for each drive pin 19. The length of each guide 22 is equal to the stroke of the piston 9.

The adjusting ring 21 can be driven in rotation about a substantially horizontal axis a to simultaneously move the pins 19 in a radial direction inside the relative guides 22 and then translate the corresponding pistons 9 along the relative channels 5.

Each channel 5 communicates with conducting means 24 suitable for being connected to a negative pressure source in order to create a vacuum condition in each calibration chamber 10, so as to suck a predetermined quantity of powdered material from hopper 3. Said conducting means 24 can also be connected to a positive pressure source to introduce a fluid flow, for example compressed air, into the passage 5, which is suitable to allow unloading of the powdered material contained in the calibration chamber 10 towards the relative container to be filled. The negative pressure source is, for example, a vacuum pump. The positive pressure source is, for example, a compressor.

The conducting means 24 comprise a plurality of conduits, one for each channel 5, which are inclined by a predetermined angle α with respect to the respective channel 5. The angle α refers to the angle comprised between the median longitudinal axis of each duct 24 and the median longitudinal axis of the channel 5. The angle alpha has a value smaller than 90 deg.. Preferably, the angle α has a value of about 50 °.

It has been experimentally observed that the arrangement of the ducts 24 with an inclination angle exhibiting the above values is advantageous in terms of fluid-dynamic properties. In particular, a reduction in turbulence phenomena is observed from the experimental results and this contributes to making the device more precise and provided with high repeatability.

The conduits 24 extend from the respective channels 5 to the rear surface of the metering wheel 2 and communicate with the distributor element 25 during certain operating steps of the metering wheel 2.

The distributor element 25 is associated with the rear surface of the metering wheel 2, and the distributor element 25 occupies a fixed position during rotation of the metering wheel 2.

The distributor element 25 is formed by a ring forming, in the shape of a circumferential arc, a first suction channel 26, the first suction channel 26 extending in the loading region, the first suction channel 26 being oriented towards the hopper 3 in the mounted configuration.

The first channel 26 is provided with at least one suction aperture 27, which suction aperture 27 is adapted to allow connection of the channel 26 to a negative pressure source to create a vacuum condition in the first channel 26.

The distributor element 25 forms, in the shape of a circumferential arc, a second channel 28, the second channel 28 being contiguous to the first channel 26, and the second channel 28 extending between the first channel 26 and an unloading area, the unloading area being opposite to the first channel 26, the second channel 28 being placed, in the installed configuration, towards the container to be filled.

The second channel 28 is also provided with a corresponding suction aperture 27, which suction aperture 27 is adapted to allow connection of the channel 28 to a negative pressure source to maintain a vacuum condition in the channel.

A third suction aperture 27 is formed at the discharge area to allow connection of the duct 24 occupying this position to a positive pressure source.

In the sector between the third suction opening 27 and the first passage 26, a third passage 29 is provided, which third passage 29 has at least one suction opening 27 for connection to a positive pressure source, in order to perform an optimum cleaning operation of the piston 9 before the subsequent filling of the chamber 10.

In view of the foregoing description, the operation of the apparatus for filling containers is readily understood.

First, the volume of the calibration chamber 10 is set based on the amount of powdered material to be inserted in the container. The adjusting ring 21 is then driven in rotation so as to simultaneously move the pins 19 in the respective radial directions and to cause the relative piston 9 to translate along the channel 5.

The metering wheel 2 is then driven in rotation around the rotation axis a at regular intervals to perform a continuous filling of the calibration chamber 10 with a predetermined quantity of powdered material and a subsequent emptying of the chamber 10.

In particular, to disclose the operating cycle of the apparatus, consider a calibration chamber 10 that initially occupies a position in the area below the hopper 3. In this position, the chamber 10 is in communication via conduit 24 with a negative pressure source that creates a vacuum in the first channel 26 and in the chamber 10. The vacuum created in the calibration chamber 10 allows to suck the powdered material and to fill said chamber 10 with a precise quantity of powdered material.

The metering wheel 2 makes the chamber 10 pass through the region corresponding to the second passage 28, wherein the vacuum is maintained such that the powdered material contained in the chamber 10 remains inside the chamber 10 itself and no material loss occurs during rotation due to the forces to which the chamber 10 is subjected.

Then, due to the flow of compressed air introduced into the chamber 10, the chamber 10 is brought to the unloading area of the powdered material and discharges the powdered material into the container located below.

Finally, the metering wheel 2 makes the chamber 10 pass through the region corresponding to the third suction channel 29, wherein the delivery of a further flow of compressed air into the chamber 10 allows to effectively clean the piston 9 and prepare the calibration chamber 10 for a new operating cycle.

The device according to the invention allows to optimally carry out the metering operations of small quantities of powdered material thanks to the configuration of the piston, and to allow an easy assembly thanks to the configuration of the passage. In particular, providing each channel of the piston with a head having a smaller cross section than the end portion of the rod allows to obtain a base surface of the calibration chamber 10 with a reduced extension and therefore a range of volume values of the chamber which is lower than those obtainable with known devices of the same type.

Considering that the piston has a head with a diameter of about 4mm, which substantially corresponds to the diameter of the base surface of the calibration chamber, and considering 0.55g/cm³The piston allows a dosage amount of material up to 20 mg.

It should be noted that the end portion of each piston, which has a cross section greater than that of the head, ensures a sufficient stability and structural strength of the adjustment assembly.

It should also be considered that the configuration of the channels according to the invention, in which each channel has a cross section that increases from the peripheral edge towards the centre of the disc-like body, allows overcoming the difficulty of installing the pistons introduced through the reduced section of the end section of each channel, since a smaller cross section is provided for the head of each piston. This configuration allows the piston to be inserted inside the respective channel from the centre of the disc-shaped body.

In this respect, it is noted that the section of each channel near the central portion of the disc-like body is configured to allow the insertion of the relative piston during assembly.

Another advantage of the invention lies in the fact that: the conduction of the flow of compressed air or the formation of the low-pressure zone in the calibration chamber allows the turbulence phenomena to be reduced by means of the inclined duct having an angle of less than 90 °, preferably less than 50 °, with respect to the central axis of the calibration chamber. In this way, load losses are reduced and this makes the loading and unloading operations of the chamber more reliable and accurate.

It has also been experimentally observed that the improved fluid dynamic behaviour of the fluid in the calibration chamber allows to obtain a high repeatability of the machine.

The apparatus disclosed by way of example may be subject to numerous modifications and variations in accordance with different requirements.

In the practical embodiment of the present invention, the materials used, as well as the shapes and dimensions, may be any according to the requirements.

The technical features mentioned in any claim are followed by reference signs which are included merely to increase the intelligibility of the claims and accordingly, they have no limiting effect on the intent of each element identified by way of example by such reference signs.

Claims

1. An apparatus for filling containers with metered quantities of powdered material, comprising a metering wheel (2) rotatable about a substantially horizontal rotation axis (a), the metering wheel (2) comprising a disc-shaped body (4), inside which a plurality of channels (5) are formed extending in respective radial directions from a peripheral edge (6) of the disc-shaped body (4) towards the centre of the disc-shaped body (4), each channel (5) having an opening (7) at the peripheral edge (6), the openings (7) putting the channel (5) in communication with the external environment;

a hopper (3), said hopper (3) being arranged above said metering wheel (2) and said hopper (3) being adapted to contain said powdery material;

a plurality of pistons (9), said pistons (9) being respectively slidably inserted inside said channels (5), each piston (9) comprising a stem (11) and a head (12) integral with one end of said stem (11), each piston (9) defining a calibration chamber (10) in said channel (5), said calibration chamber (10) being arranged to collect a metered quantity of said powdery material, said calibration chamber (10) being delimited by the head (12) of the piston (9) concerned and by the inner wall of the respective channel (5);

an adjustment assembly (18), said adjustment assembly (18) being associated with said metering wheel (2), said adjustment assembly (18) being adapted to adjust the position of each piston (9) inside the respective channel (5);

-conducting means (24), said conducting means (24) being in communication with said channel (5), and said conducting means (24) being adapted to be alternately connected to a negative pressure source and to a positive pressure source, so as to generate a vacuum state in each of said calibration chambers (10) respectively, and so as to introduce a fluid flow inside said calibration chambers (10),

the device is characterized in that the head (12) of each piston (9) has a cross section such as: said cross-section having a diameter (d4) smaller than the diameter (d1) of the cross-section of an end portion (15) of the stem (11), said end portion (15) being opposite to the head (12), and wherein each channel (5) has a cross-section that increases from the peripheral edge (6) towards the centre of the disc-shaped body (4).

2. The apparatus according to claim 1, wherein the diameter (d4) of the cross-section of the head (12) has a value in the range of about 3.5mm to about 4 mm.

3. The apparatus according to claim 1, characterized in that the diameter (d4) of the cross section of the head (12) has a value of about 4 mm.

4. The device according to claim 1, 2 or 3, characterized in that the channels (5) are regularly distributed on the disc-shaped body (4), the channels (5) being arranged at the same angular distance with respect to each other.

5. The apparatus according to one of the preceding claims, wherein each channel (5) comprises a section near the central portion (C) of the disc-like body (4) configured to allow the insertion of the relative piston (9) during assembly.

6. The apparatus according to claim 5, characterized in that said section in proximity of said central portion (C) of the disc-shaped body (4) has a cross section greater than the cross section of the end portion (15) of the piston (9) concerned.

7. The apparatus according to one of the preceding claims, characterized in that each channel (5) comprises, on the side of the peripheral edge (6), an end section (8), the end section (8) having a cross-sectional diameter (d0) substantially corresponding to the cross-sectional diameter (d4) of the head (12) of the piston (9) concerned, unless play is present.

8. The apparatus according to one of the preceding claims, characterized in that said conducting means (24) comprise a plurality of ducts, one for each channel (5), said ducts (24) being inclined with respect to the respective channel (5) by a predetermined inclination angle (a) having a value less than 90 °.

9. The apparatus according to claim 8, characterized in that said inclination angle (a) has a value of about 50 °.

10. The apparatus according to one of the preceding claims, characterized in that the head (12) comprises a filtering element (13), the filtering element (13) being provided with a plurality of holes (14), the holes (14) being able to ensure the permeability of the head (12) to gaseous media and the impermeability of the head (12) to the powdery material.