WO2020100005A1

WO2020100005A1 - Mixing head

Info

Publication number: WO2020100005A1
Application number: PCT/IB2019/059659
Authority: WO
Inventors: Nicola VARUTTI; Elvis TURCATO
Original assignee: Tt Italy S.P.A.
Priority date: 2018-11-13
Filing date: 2019-11-11
Publication date: 2020-05-22
Also published as: IT201800010291A1

Abstract

A mixing head (1) comprises an outer casing (2) surrounding a mixing chamber (3) that extends along an axis (X). A rotor (10) is arranged inside a processing portion (3b) of the mixing chamber (3) and is surrounded by a stator (7) solidly constrained to the outer casing (2). The rotor (10) is internally hollow and forms a thermal stabilization chamber (16) in fluid communication with a delivery duct (17) and a return duct (20) to be crossed by a fluid.

Description

“Mixing head”

DESCRIPTION

TECHNICAL FIELD

This invention is applied to the food industry.

In particular, the invention relates to a mixing head and is applied for example in the pastry industry to obtain emulsified and aerated creams. Even more in particular, the mixing head according to this invention is applied in continuously operating mixing apparatuses.

Furthermore, the invention relates to a mixing method which can be actuated in continuously operating mixing apparatuses.

* * * * *

PRIOR ART

The known mixing heads are designed to emulsify creams and to aerate them, in order to obtain the desired final specific weight. A cream is fed to the mixing head, optionally adding further ingredients, to be emulsified and aerated also by introducing air or another gas, for example nitrogen. The mixing takes place as a result of the joint action of a suitably configured rotor/stator system. In particular, while the rotor rotates in the stator, the respective series of alternating blades generates a variable passageway within which the cream passes that then undergoes a continuous mixing and an intimate mixing of the components and the gaseous part. Some examples of known systems are described in prior art documents DE 31 30 968, DE 3715 774, US 2 973 946.

As is known, the rotation of the rotor in the stator generates heat as a result of the friction. The Applicant has observed that the uncontrolled generation of heat adversely affects the final result, which is variable as a function of the temperature conditions that are generated in the mixing head.

Cooling systems have been perfected in which the mixing head is externally cooled, for example by means of water circulating in an external gap. Also in this case, the Applicant has observed a non-predictable variability of the characteristics of the final product due to the non-uniform distribution of the temperature inside the mixing head. In particular, since the cooling is external, it is difficult to control the temperature of the product circulating in proximity to the rotor.

Furthermore, the rotor/stator system, and in particular its blades and the respective passageways, are oversized to ensure the attainment of a certain temperature inside the mixing chamber, limiting the intimate mixing effect obtainable. Finally, the temperature of the water circulating in the gap must be forcibly maintained low to allow reaching the required temperature throughout the entire mixing chamber and to compensate thermal losses towards the outside.

SUMMARY

In this context, the technical task underlying the present invention is to provide a mixing head, in particular for continuously operating mixing apparatuses, and a mixing method which obviate at least some of the drawbacks in the prior art as described above.

In particular, an object of the present invention is to provide a mixing head and method capable of improving and making the qualitative characteristics of the final product constant.

A further object of the present invention is to limit the size of the blades of the rotor/stator system and the respective passageways to ensure an intimate mixing of the cream, while ensuring the optimal management of the temperature inside the mixing chamber.

Still a further object of the present invention is to minimize the thermal losses.

The technical task set and the objects specified are substantially attained by a mixing head and method, comprising the technical characteristics as set out in one or more of the accompanying claims. The dependent claims correspond to further advantageous aspects of the invention.

It should be highlighted that this summary introduces, in simplified form, a selection of concepts which will be further elaborated in the detailed description given below.

In particular, in accordance with a first aspect, the present invention relates to a mixing head adapted to be used for continuously operating mixing apparatuses. The mixing head comprises a rotor/stator system in which the rotor is internally hollow and forms a thermal stabilization chamber in fluid communication with a delivery duct and a return duct to be crossed by a fluid, preferably water.

In accordance with a second aspect, the present invention relates to a mixing method which can be actuated in continuously operating mixing apparatuses. The mixing method provides preparing a mixing chamber comprising a rotor/stator system and introducing a cream to be mixed into the mixing chamber, driving the rotor in rotation. The mixing chamber is thermally stabilized by introducing a fluid, preferably water, in the internally hollow rotor and controlling the temperature thereof.

The Applicant believes that the introduction of a fluid inside the rotor allows improving and making the qualitative characteristics of the final product reproducible, also reducing the size of those parts which act as a heat exchanger so as to allow an optimum emulsion and aeration while simultaneously avoiding thermal losses.

In one or more of the aspects specified, the present invention can comprise one or more of the following features.

The mixing head comprises an outer casing that surrounds a mixing chamber. The mixing chamber extends along an axis and has at least one processing portion, preferably an inlet portion, the processing portion and an output portion distributed along the axis.

The rotor is arranged inside the processing portion. The rotor has a plurality of annular rotary mixing portions axially distributed at a radially external surface of the rotor. Each annular rotary mixing portion comprises a plurality of rotor blades distributed circumferentially around the axis and extending in a centrifugal direction from the radially external surface of the rotor. The stator, solidly constrained to the outer casing, has an annular shape around the axis and encircles the rotor in a radially external position at least at the processing portion of the mixing chamber. The stator has a plurality of annular stator mixing portions arranged alternating with the annular rotary mixing portions and meshing with them. Each annular stator mixing portion comprises a plurality of stator blades distributed circumferentially around the axis and extending in a centripetal direction from a radially internal surface of the stator.

Preferably a control unit is provided comprising cooling/heating systems for maintaining a controlled temperature, preferably constant, of the fluid introduced into the thermal stabilization chamber.

Preferably the rotating shaft comprises at least one of the delivery duct and the return duct. The delivery duct extends from a fluid inlet to a first connecting section arranged at the thermal stabilization chamber. The return duct extends from a second connecting section arranged at the thermal stabilization chamber at a fluid outlet.

The Applicant believes that providing at least one of the delivery duct and the return duct within the rotating shaft allows simplifying the creation and the operation of the mixing head.

Preferably the rotating shaft extends inside the rotor so as to create the thermal stabilization chamber having an annular shape around the rotating shaft so as to strengthen the structure of the rotor and simplify the introduction and exit of the fluid into and out of the thermal stabilization chamber.

Preferably the mixing head comprises at least one of an annular delivery chamber and an annular return chamber. The annular delivery chamber is arranged around the rotating shaft at the fluid inlet and is connectable to a fluid supply system. The annular return chamber is arranged around the rotating shaft at the fluid outlet and is connectable to a fluid recovery system. The Applicant believes that the provision of an annular delivery chamber and/or an annular return chamber limits the risks of losses and leakage. Preferably the rotating shaft is created through at least two coaxial components, inserted one inside the other, in which one or both components are shaped so as to create the delivery duct and/or the return duct. Even more preferably the rotating shaft comprises a tubular element which extends along the axis of the mixing chamber and an elongated body arranged inside the tubular element. The tubular element and/or the elongated body are shaped so as to create the delivery duct and/or the return duct.

The Applicant believes that providing the rotating shaft with a two- component structure allows simplifying the creation and assembly of the mixing head.

Preferably the rotating shaft comprises head elements arranged in axially opposite positions and configured to lock the elongated body inside the tubular element.

This provision allows simplifying the assembly, ensuring the correct positioning of the rotating shaft components and their maintenance in position even during the rotation of the rotor.

Preferably the elongated body has a delivery groove configured to create at least a portion of the delivery duct. Even more preferably the delivery groove is parallel to the axis of the mixing chamber.

Preferably the elongated body has a return groove configured to create at least one portion of the return duct. Even more preferably the return groove is parallel to the axis.

Preferably the delivery groove and the return groove are arranged in different angular positions around the axis of the mixing chamber, even more preferably in diametrically opposite positions.

The creation by means of grooves, preferably diametrically opposite, allows a fast and precise processing carried out on the easily accessible external surfaces which can be positioned relative to the tool and also ensures the correct structural and functional distinction between the two ducts.

Preferably the tubular element has a first delivery through hole and a second delivery through hole. The first delivery through hole opens into the delivery groove in a position to create the fluid inlet. The second delivery through hole opens into the delivery groove in a position to create the first connecting section.

Preferably the tubular element has a first return through hole and a second return through hole. The first return through hole opens into the return groove in a position to create the fluid outlet. The second return through hole opens into the return groove in a position to create the second connecting section.

Preferably the first delivery through hole and the first return through hole are staggered along the axis of the mixing chamber.

Preferably the second delivery through hole and the second return through hole are staggered along the axis of the mixing chamber.

Preferably the outer casing has a gap arranged at least partially around the processing portion of the mixing chamber. The Applicant believes that by carrying out both internal and external temperature control, the temperature inside the mixing chamber can be made more uniform, and thus further improve the properties of the final product, and it can reduce the overall dimensions in particular of the rotor and stator blades which act as heat exchangers, while simultaneously improving the quality of the emulsion and aeration of the cream.

Preferably two axially successive stator mixing portions are arranged at a mutual axial distance comprised between 9 mm and 1 1 mm, even more preferably equal to 10 mm.

Preferably, each annular stator mixing portion has an axial extension comprised between 5 mm and 7 mm, even more preferably equal to 6 mm. Preferably two successive stator blades around the axis are arranged at a mutual angular distance comprised between 8° and 10°, even more preferably equal to 9°.

Preferably a stator blade has a radial extension comprised between 24 mm and 26 mm, even more preferably equal to 25 mm. Preferably two axially successive annular rotor mixing portions are arranged at a mutual axial distance comprised between 9 mm and 1 1 mm, even more preferably equal to 10 mm.

Preferably each annular rotor mixing portion has an axial extension comprised between 5 mm and 7 mm, even more preferably equal to 6 mm. Preferably two successive rotor blades around the axis are arranged at a mutual angular distance comprised between 8° and 10°, even more preferably equal to 9°.

Preferably a rotor blade has a radial extension comprised between 27 mm and 27.50 mm, even more preferably equal to 27.25 mm.

Preferably when a rotor blade is axially aligned with a stator blade a passageway is generated between the rotor and stator having both axial and radial thickness comprised between 1 .5 mm and 2.5 mm, even more preferably equal to 2 mm.

The stator and rotor blades have reduced dimensions and are approached to each other, making a broad utilization available and an optimum dispersion of the gaseous and liquid ingredients.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will become more apparent from the following indicative, and hence non-limiting, description of a preferred, but not exclusive, embodiment of a mixing head. This description will be set out below with reference to the appended drawings, which are provided solely for indicative and therefore non-limiting purposes, in which:

- figure 1 schematically shows a partially sectioned side view of a mixing head;

- figure 2 schematically shows a sectional view of a mixing head according to the line ll-ll of figure 1 ;

- figure 3 shows a longitudinal sectional view of a possible embodiment of a mixing head; - figure 4 shows a perspective view of an element belonging to the mixing head of figure 3;

- figure 5 shows an enlarged detail of an element belonging to the mixing head of figure 3;

- figure 6 shows an enlarged detail of an element belonging to the mixing head of figure 3;

- figure 7 shows an enlarged detail of the mixing head of figure 3;

- figure 8 shows an enlarged detail of a transversal sectional view according to the line VIII-VIII of figure 3.

DETAILED DESCRIPTION

The present invention relates to a mixing head.

With reference to the figures, the number 1 generally indicates a mixing head, preferably adapted to continuously operating mixing apparatuses. The other numerical references refer to technical features of the invention which, barring indications otherwise or evident structural incompatibilities, the person skilled in the art will know how to apply to all the variant embodiments described.

Any modifications or variants which, in the light of the description, are evident to the person skilled in the art, must be considered to fall within the scope of protection established by the present invention, according to considerations of technical equivalence.

The mixing head 1 comprises an outer casing 2 surrounding at least one mixing chamber 3.

The mixing chamber 3 extends along an axis "X". As for example illustrated in figure 3, the mixing chamber 3 has an inlet portion 3a, a processing portion 3b and an outlet portion 3c arranged in sequence along the axis "X". The inlet portion 3a preferably has tapered shape, which narrows away from the processing portion 3b, and is placed in communication with the exterior through a first supply duct 4a for example adapted to be put in communication with a supply system of creams and/or liquid mixtures to be mixed and a second supply duct 4b adapted to be placed in communication with a gas supply system, for example air or nitrogen. Preferably the first supply duct 4a and the second supply duct 4b are combined into a single supply duct 4 at least at the inlet portion 3a. Preferably the supply duct 4 is arranged radially relative to the axis "X".

The processing portion 3b has a substantially cylindrical shape around the axis "X".

The outlet portion 3c preferably has tapered shape, which narrows away from the processing portion 3b, and is placed in communication with the exterior through an outlet duct 5 through which the emulsified and aerated cream is sent to the subsequent processing. Preferably the outlet duct 5 is arranged coaxially to the axis "X".

The outer casing 2 has a gap 6 arranged at least partially around the mixing chamber 3. Preferably the gap 6 has an annular shape around the axis "X". Even more preferably the gap 6 encircles at least the processing portion 3b of the mixing chamber 3. As for example illustrated in figure 2 and 3, the gap 6 encircles the processing portion 3b and extends further at the outlet portion 3c. Preferably the gap 6 can also extend to the inlet portion 3a or at least to sections thereof.

The gap 6 is adapted to receive a fluid, for example water, adapted to carry out the thermal stabilization function. The fluid is introduced and extracted in the gap with continuity by means of a circulation system, for example by means of a hydraulic pump. To control the mixing parameters, the fluid is introduced in the gap 6 at a controlled temperature. Preferably the temperature of the fluid introduced in the gap 6 is constant, less than or greater than the temperature reached inside the mixing chamber 3. In most of the cases where the cooling improves the mixing, the fluid can be maintained at a controlled temperature lower than the temperature reached inside the mixing chamber 3. In this way it is also possible to counteract the production of heat due to the mixing itself. In the cases where the mixing is favoured by heat, the fluid can be maintained at a controlled temperature greater the temperature reached inside the mixing chamber 3.

The number 7 indicates a stator solidly constrained to the outer casing 2 and laterally delimiting the processing portion 3b of the mixing chamber 3. The stator 7 has an annular shape around the axis "X" and preferably defines a delimiting inner side wall of the gap 6. In other words, the gap 6 is arranged around the stator 7 and in a radially external position thereto.

In accordance with a possible embodiment, the stator 7 has a plurality of annular stator mixing portions 8 distributed along the axis "X" at a radially internal surface of the stator 7. Each annular stator mixing portion 8 comprises a plurality of stator blades 9 (figure 6) distributed circumferentially around the axis“X” and extending in a centripetal direction from the radially internal surface of the stator 7. Preferably each stator blade 9 has a radial shape.

Preferably two successive annular stator mixing portions 8 along the axis "X” are arranged at a mutual axial distance D1 comprised between 9 mm and 1 1 mm, preferably equal to 10 mm (figure 6).

Preferably each annular stator mixing portion 8, namely each stator blade 9, has an axial extension L1 comprised between 5 mm and 7 mm, preferably equal to 6 mm (figure 6).

Preferably two successive stator blades 9 around the axis“X” are arranged at a mutual angular distance b1 comprised between 8° and 10°, preferably equal to 9° (figure 8).

Preferably a stator blade 9 has a radial extension R1 comprised between 24 mm and 26 mm, preferably equal to 25 mm (figure 6).

The number 10 indicates a rotor arranged inside the processing portion 3b of the mixing chamber 3 and rotating around a rotation axis coinciding with the axis "X" of the mixing chamber 3.

The rotor 10 has a cylindrical shape around the axis "X" and is encircled by the stator 7 arranged at a radially external position with respect thereto at the processing portion 3b of the mixing chamber 3. In accordance with a possible embodiment, the rotor 10 has a plurality of annular rotor mixing portions 1 1 distributed along the axis "X" at a radially external surface of the rotor 10.

Each rotor stator mixing portion 1 1 comprises a plurality of rotor blades 12 (figure 8) distributed circumferentially around the axis“X” and extending in a centrifugal direction from the radially external surface of the rotor 10. Preferably each rotor blade 12 has a radial shape.

Preferably two successive annular rotor mixing portions 1 1 along the axis "X” are arranged at a mutual axial distance D2 comprised between 9 mm and 1 1 mm, preferably equal to 10 mm (figure 5).

Preferably each annular rotor mixing portion 1 1 , namely each rotor blade 12, has an axial extension L2 comprised between 5 mm and 7 mm, preferably equal to 6 mm (figure 5).

Preferably two successive rotor blades 12 around the axis“X” are arranged at a mutual angular distance b2 comprised between 8° and 10°, preferably equal to 9° (figure 8).

Preferably a rotor blade 12 has a radial extension R2 comprised between 27 mm and 27.50 mm, preferably equal to 27.25 mm (figure 5).

The annular rotor mixing portions 1 1 are arranged in an alternating manner with the annular stator mixing portions 8 along the axis "X" and meshing with them. When a rotor blade 12 is axially aligned with a stator blade 9 a passageway“M” is generated between the rotor 10 and stator 7 (figure 7) having both axial and radial thickness comprised between 1 .5 mm and 2.5 mm, preferably equal to 2 mm.

The rotor 10 is mounted on a rotating shaft 13, also arranged with a rotation axis coinciding with the axis "X" of the mixing chamber 3.

The rotating shaft 13 can be mounted on bearings 14 housed in a support 15 preferably created as an appendage of the outer casing 2.

Advantageously the rotor 10 is internally hollow and forms a thermal stabilization chamber 16 in fluid communication with a delivery duct 17 and a return duct 20 to be crossed by a fluid, preferably water. The fluid is introduced and extracted with continuity in the thermal stabilization chamber

16 by means of a circulation system, for example by means of a hydraulic pump.

Preferably the rotating shaft 13 extends along the axis "X" at least partially inside the rotor 10, for example inserting into a first head opening 10a arranged at one axial end of the rotor itself. In this way a thermal stabilization chamber 16 is obtained of at least partially annular shape around the rotating shaft 13.

Even more preferably the rotating shaft 13 axially crosses the entire rotor 10, extending between axially opposite ends of the rotor itself, starting from the first head opening 10a and preferably until it is inserted into a second head opening 10b arranged at the opposite axial end of the rotor. In this way a thermal stabilization chamber 16 is obtained of annular shape around the rotating shaft 13.

To control the mixing parameters, the fluid is introduced in the thermal stabilization chamber 16 at a controlled temperature. Preferably the temperature of the fluid that is introduced in the thermal stabilization chamber 16 is constant, less than or greater than the temperature reached inside the mixing chamber 3. In most of the cases where the cooling improves the mixing, the fluid can be maintained at a controlled temperature lower than the temperature reached inside the mixing chamber 3. In this way it is also possible to counteract the production of heat due to the mixing itself. In the cases where the mixing is favoured by heat, the fluid can be maintained at a controlled temperature greater the temperature reached inside the mixing chamber 3.

The fluid introduced in the gap 6 and/or that introduced in the thermal stabilization chamber 16 are managed by a control unit“C” comprising suitable cooling/heating systems for maintaining a controlled temperature, preferably constant.

Preferably the rotating shaft 13 comprises at least one of the delivery duct

17 and the return duct 20. The delivery duct extends from a fluid inlet 18 to a first connecting section 19 arranged at the thermal stabilization chamber 16 and the return duct 20 extends from a second connecting section 21 arranged at the thermal stabilization chamber 16 to a fluid outlet 22.

The fluid inlet 18 and the fluid outlet 22 are preferably staggered along the axis "X".

The first connecting section 19 and the second connecting section 21 are preferably staggered along the axis "X". Even more preferably, the first connecting section 19 and the second connecting section 21 are arranged at axially opposite ends of the rotor 10.

As for example shown in figure 3, the number 23 indicates an annular delivery chamber arranged around the rotating shaft 13 at the fluid outlet 18 and connectable to a fluid recovery system through an external inlet 24. The number 25 indicates an annular return chamber arranged around the rotating shaft 13 at the fluid outlet 22 and connectable to a fluid recovery system through an external outlet 26.

Preferably the annular delivery chamber and the annular return chamber are defined inside the support 15, for example by means of at least one bushing 27. In this case suitable passages formed in the support 15 and possibly in the bushing(s) 27 define the external inlet 24 and the external outlet 26.

In accordance with a possible embodiment, for example shown in figure 3, the annular delivery chamber and the annular return chamber are formed in a single bushing 27 by means of seals 28. Alternatively, two separate bushings can be provided.

In accordance with a possible embodiment, of which the attached drawings form a non-limiting example, the rotating shaft 13 comprises a tubular element 13a which extends along the axis "X" and an elongated body 13b, preferably cylindrical, arranged inside the tubular element 13a (figure 3). The rotating shaft 13 is preferably made of steel, preferably AISI304, AISI316 or DUPLEX, and the elongated body 13b is preferably made of plastic material, such as for example high density polyethylene. To lock the elongated body 13b inside the tubular element 13a, head elements 29a, 29b can be used arranged in axially opposite positions of the rotating shaft 13. Preferably the two head elements 29a, 29b and the elongated body 13b are shaped to create a shape coupling configured to prevent the rotation of the elongated body 13b inside the tubular element 13a. For example at least one head end of the elongated body 13b, preferably both ends, has a transverse notch 30 adapted to receive a respective transverse tooth 31 of one of the head elements 29a, 29b.

At least the head element 29a associated with the rotor 10 comprises a cap 32 that abuts against the head surface of the rotor 10, externally thereto. Preferably, the tubular element 13a and/or the elongated body 13b are removable by acting from the exterior of the rotor 10 and pulling them through from the first head opening 10a.

Preferably the tubular element 13a and/or the elongated body 13b are shaped to create the delivery duct 17 and/or the return duct 20.

In accordance with one possible example, the elongated body 13b can have a delivery groove 33, preferably parallel to the axis“X”, and configured to create at least one portion of the delivery duct 17. In this case the tubular element 13a can have a first delivery through hole 34a, opening in the delivery groove 33 in a position to create the fluid inlet 18. In addition or alternatively, the tubular element 13a can have a second delivery through hole 34b, opening in the delivery groove 33 in a position to create the first connecting section 19.

Preferably the annular delivery chamber 23, if present, is arranged around the tubular element 13a at the first delivery through hole 34a.

In accordance with one possible example, the elongated body 13b can have a return groove 35, preferably parallel to the axis“X”, and configured to create at least one portion of the return duct 20. In this case the tubular element 13a can have a first return through hole 36a, opening in the return groove 35 in a position to create the fluid outlet 22. In addition or alternatively, the tubular element 13a can have a second return through hole 36b, opening in the return groove 35 in a position to create the second connecting section 21 .

Preferably the annular return chamber 25, if present, is arranged around the tubular element 13a at the first return through hole 36a.

In the case where both are provided, the first delivery through hole 34a and the first return through hole 36a are preferably staggered along the axis "X" so as to stagger the fluid inlet 18 and the fluid outlet 22.

In the case where both are provided, the second delivery through hole 34b and the second return through hole 36b are preferably staggered along the axis "X" so as to stagger the first connecting section 19 and the second connecting section 21 . Even more preferably the second delivery through hole 34b and the second return through hole 36b are arranged at axially opposite ends of the rotor 10. Preferably, the second return through hole 36b is arranged at a bottom wall of the rotor 10 at the axial end of the shaft 13.

In the case where both are present, the delivery groove 33 and the return groove 35 are arranged in different angular positions around the axis“X”, preferably in diametrically opposite positions.

Preferably, the elongated body 13b and the tubular element 13a extend along the entire length of the rotating shaft 13. The delivery groove 33 extends, preferably, along the entire length of the rotating shaft 13.

In accordance with another aspect of the present invention, the delivery groove and/or the return groove 35 is unique and extends continuously along the rotating shaft.

The mixing head 1 allows efficiently emulsifying in an environment with a controlled and ideal temperature for the process, ensuring consistent and repeatable results.

In use, the mixing head 1 allows actuating a mixing method in which the cream to be mixed is introduced into the mixing chamber 3 and the rotor 10 is driven in rotation. During the mixing, the mixing chamber 3 is thermally stabilized by introducing a fluid, preferably water, in the internally hollow rotor 10. The temperature of the fluid is controlled and is preferably maintained constant.

Preferably the fluid is introduced and extracted with continuity both in the rotor 10, and in the gap 6, by activating the relative circulation system that can be shared.

The mixing takes place continuously, emulsifying and aerating the cream following the rotor/stator interaction and optionally further introducing a gas, for example nitrogen, in the inlet portion of the mixing chamber. The mixed cream then proceeds in output from the mixing chamber.

The internal control of the temperature preferably in conjunction with the external control of the temperature allow a uniform and repeatable distribution of the thermal conditions inside the mixing chamber.

Claims

1. A mixing head (1 ) for continuously operating mixing apparatuses, comprising:

an outer casing (2) surrounding a mixing chamber (3) which extends along an axis (X) and comprising at least one processing portion (3b); a rotor (10) arranged inside the processing portion (3b) of the mixing chamber (3), wherein the rotor (10) has a plurality of annular rotor mixing portions (1 1 ) distributed along said axis (X) at a radially external surface of the rotor (10), each annular rotor mixing portion (1 1 ) comprising a plurality of rotor blades (12) distributed circumferentially around said axis (X) and extending in a centrifugal direction from the radially external surface of the rotor (10);

a stator (7) solidly constrained to the outer casing (2), having an annular shape around said axis (X) and encircling the rotor (10) in a radially external position thereto at least at the processing portion (3b) of the mixing chamber (3), wherein the stator (7) has a plurality of annular stator mixing portions (8) arranged in an alternating manner with the annular rotor mixing portions (1 1 ) and meshing with them, each annular stator mixing portion (8) comprising a plurality of stator blades (9) distributed circumferentially around the axis (X) and extending in a centripetal direction from a radially internal surface of the stator (7);

said rotor (10) being internally hollow and forming a thermal stabilization chamber (16) in fluid communication with a delivery duct (17) and a return duct (20) to be crossed by a fluid.

a rotating shaft (13) arranged with its rotation axis coinciding with said axis (X) wherein said rotating shaft (13) extends inside the rotor (10) so as to create said thermal stabilization chamber (16) having an annular shape around the rotating shaft (13); said rotor (10) being mounted on said rotating shaft (13), wherein said rotating shaft (13) comprises at least one of the delivery duct (17) and the return duct (20), wherein said delivery duct (17) extends from a fluid inlet (18) to a first connecting section (19) arranged at the thermal stabilization chamber (16) and wherein said return duct (20) extends from a second connecting section (21 ) arranged at the thermal stabilization chamber (16) to a fluid outlet (22).

characterized in that said rotating shaft (13) comprises a tubular element (13a) which extends along said axis (X) and an elongated body (13b) arranged inside the tubular element (13a) and wherein said tubular element (13a) and/or said elongated body (13b) are shaped so as to create said delivery duct (17) and/or said return duct (20).

said elongated body (13b) having a delivery groove (33) configured to create at least one portion of the delivery duct (17); said tubular element (13a) having a first delivery through hole (34a), opening in the delivery groove (33) in a position to create the fluid inlet (18), and a second delivery through hole (34b), opening in the delivery groove (33) in a position to create the first connecting section (19) arranged at the thermal stabilization chamber (16).

2. The mixing head according to claim 1 , wherein said elongated body (13b) has a return groove (35) configured to create at least one portion of the return duct (20).

3. The mixing head according to claims 1 and 2, wherein said delivery groove (33) and/or said return groove (35) is parallel to the axis (X).

4. The mixing head according to claim 3, wherein the delivery groove (33) and/or the return groove (35) is unique and extends continuously along the rotating shaft (13).

5. The mixing head according to any one of claims 1 to 4, wherein said tubular element (13a) has a first return through hole (36a), opening in the return groove (35) in a position to create the fluid outlet (22).

6. The mixing head according to claim 5, wherein said tubular element (13a) has a second return through hole (36b), opening in the return groove (35) in a position to create the second connecting section (21 ).

7. The mixing head according to any one of the previous claims, characterised in that it comprises an annular return chamber (25) arranged around the rotating shaft (13) at the fluid outlet (22) and connectable to a fluid recovery system through an external outlet (26).

8. The mixing head according to claim 7 when dependent on claim 5, wherein said annular return chamber (25) is arranged around the tubular element (13a) at the first return through hole (36a).

9. The mixing head according to any one of the previous claims, wherein said delivery groove (33) and said return groove (35) are arranged in different angular positions around the axis (X), preferably in diametrically opposite positions.

10. The mixing head according to claim 9 when dependent on claim 5, wherein said first delivery through hole (34a) and said first return through hole (36a) are preferably staggered along the axis "X" so as to stagger the fluid inlet (18) and the fluid outlet (22).

11. The mixing head according to claim 10 when dependent on claim 6, wherein said second delivery through hole (34b) and said second return through hole (36b) are arranged at axially opposite ends of the rotor (10) .

12. The mixing head according to one or more of the previous claims, wherein said rotating shaft (13) axially crosses the entire rotor (10), extending between axially opposite ends of the rotor itself, starting from the first head opening (10a) preferably until it is inserted into a second head opening (10b) arranged at the opposite axial end of the rotor.

13. The mixing head according to claim 12, wherein the elongated body (13b) and the tubular element (13a) extend along the entire length of the rotating shaft (13).

14. The mixing head according to claim 13, wherein said elongated body (13b) is locked inside the tubular element (13a) through head elements (29a, 29b) arranged in axially opposite positions of the rotating shaft (13).

15. The mixing head according to claim 14, wherein at least the head element (29a) associated with the rotor (10) comprises a cap (32) that abuts against the head surface of the rotor (10), external thereto such that the shaft can be disconnected from the outside.

16. The mixing head according to one or more of the previous claims, wherein said outer casing (2) has a gap (6) arranged at least partially around the processing portion (3b) of the mixing chamber (3) and adapted to receive a fluid adapted to perform the function of thermal stabilization from the outside.

17. The mixing head according to one or more of the preceding claims, comprising a control unit (C) comprising cooling/heating systems for maintaining a controlled temperature, preferably constant, of the fluid introduced into the thermal stabilization chamber (16).