AND RELATED CONTINUOUS COMPOUND MIXING PLANT

DESCRIPTION

Technical field of the invention

The present invention regards a continuous compound mixing plant, in particular for polymeric compounds, and a method for assembling or disassembling a continuous compound mixer. In particular, the present invention regards the field of testing and/or producing elastomeric and thermoplastic compounds used for manufacturing tyres for vehicle wheels.

State of the art

The continuous compound mixers in question are compound mixers provided with at least one extrusion screw housed in a compound mixing chamber which extends between one or more inlets and an outlet. The compound mixing chamber is delimited by a plurality of outer cylindrical bodies or shells which are arranged in continuous succession along a main axis of the compound mixer and joined to each other, for example by means of bolted flanges. Such compound mixers are capable of processing the elastomeric compounds or the thermoplastic compounds with continuity over time, producing a continuous flow of outflowing compound, contrary to batch compound mixers which require the loading, processing and unloading of each batch.

One-screw and multi-screw, for example two-screw continuous compound mixers are known.

Known are continuous compound mixers comprising a fixed central spindle and a plurality of lateral screws surrounding the central spindle, extending parallel to the central spindle and each rotating around an axis thereof. An example of such compound mixers is illustrated in the document WO 2010/004595.

Planetary continuous compound mixers, referred to in the technical jargon as ‘planetary roller extruders’ are also known. Typically, planetary continuous compound mixers comprise one or more compound mixing sections in continuous succession, each section comprising a respective outer body or shell which defines a respective internal compound mixing chamber. A central spindle traverses all the internal chambers of the compound mixing sections, coaxially to the internal chambers. Furthermore, each compound mixing section comprises, housed in the respective internal chamber, a respective plurality of planetary spindles which surround, and are meshed, with the central spindle, so that a rotation of the central spindle (by a motor of the continuous compound mixer) triggers, for each planetary spindle, a (counter)-rotating motion around an axis thereof and a translation motion along a circular trajectory coaxial to the central spindle. The contact surfaces of the central spindle, of the planetary spindles and of the internal chambers are adapted to allow the meshing of the planetary spindles with the central spindle on the one hand and with the surface of the internal chamber on the other. Typically, positioned between one compound mixing section and the subsequent compound mixing section (and downstream of the latter compound mixing section) is a stop ring which has the main function of holding the planetary spindles of the compound mixing sections in place. Examples of planetary continuous compound mixers are illustrated in documents US 4,192,617 and US 8,957,119.

Summary

The Applicant observed that, in order to disassemble a continuous compound mixer, for example for carrying out maintenance and/or reconfiguration operations (particularly frequent when testing processes and the devices for producing elastomeric compounds for tyres), depending on the type of compound mixer, each stage of the body or outer cylindrical shell or the entire outer cylindrical body must be respectively disconnected from the adjacent stage or from the compound mixer assembly and moved away before or after removing the extrusion screw/s.

In particular, the Applicant observed that in planetary continuous compound mixers, after removing the planetary spindles, each outer cylindrical shell must be slipped off from the central spindle, which remains in place, by making it slide thereon and parallel to a central axis of the compound mixer. Likewise, the assembling operation is carried out by fitting the cylindrical shells onto the central spindle one after the other.

The Applicant observed that these operations must be carried out ensuring perfect coaxiality between each outer cylindrical shell and the central spindle so as to avoid damaging interferences between the parts in relative movement. Thus, the Applicant observed the need for being able to assemble and disassemble the continuous compound mixers illustrated above in a precise, quick and simple manner.

Furthermore, the Applicant observed that installed above the continuous compound mixers are raised parts of the plant designated to contain and convey the elastomeric materials and other possible components inside the compound mixers by means of one or more hoppers also mounted above each compound mixer. Power supply members can also be present on the sides of the continuous compound mixers.

The Applicant observed that the overall dimension of the aforementioned parts of the plant is such to prevent the manufacturing and positioning of the fixed devices (such as pulleys moving on tracks) suitable to allow the displacement of the cylindrical shells so as to assemble or disassemble the respective continuous compound mixer.

Thus, the Applicant felt the need for being able to carry out the assembling and disassembling operations without using apparatus that are complex, cumbersome and expensive which, given that they are to be housed in the testing and/or production sites and in proximity of the continuous compound mixers, would be difficult to obtain and implement.

The Applicant found that the aforementioned assembling and disassembling operations can be implemented by means of an extensible arm positioned and configured so as to be removed or retracted so as to bring the distal end of the arm at each compound mixing section and thus at each outer cylindrical shell. According to a first aspect, the present invention regards a method for assembling or disassembling a continuous compound mixer for polymeric compounds, preferably elastomeric and thermoplastic, said compound mixer comprising an outer cylindrical body comprising at least one outer cylindrical shell, said method comprising:

providing an apparatus for assembling or disassembling a continuous compound mixer comprising a base, an upright mounted on the base and an extensible arm supported by the upright facing the continuous compound mixer;

positioning said extensible arm substantially parallel to a main axis of said continuous compound mixer; removably engaging the outer cylindrical shell of the continuous compound mixer to an end of the extensible arm;

moving said base with respect to the ground and/or extending or retracting said extensible arm and displacing the outer cylindrical shell along a direction parallel to the main axis of said continuous compound mixer.

According to a second aspect, the present invention regards a continuous compound mixing plant comprising a continuous compound mixer for polymeric compounds, preferably elastomeric and thermoplastic, and an apparatus for assembling or disassembling a continuous compound mixer, wherein the apparatus comprises:

a base configured to rest against the ground;

an upright mounted on the base;

an extensible arm supported by the upright, spaced from the base and extending along a substantially horizontal direction with respect to the ground;

an engagement device positioned or positionable at an end of the extensible arm and configured to removably engage an outer cylindrical shell of the continuous compound mixer.

Preferably, the apparatus is used for implementing the method subject of the first aspect.

Preferably, the outer cylindrical body comprises a plurality of outer cylindrical shells arranged in continuous succession along the main axis. The method comprises engaging said outer cylindrical shells to the end of the extensible arm and displacing them along the direction parallel to the main axis one after the other.

Preferably, the continuous compound mixer comprises at least one compound mixing section comprising a respective outer cylindrical shell delimiting a respective internal compound mixing chamber.

Preferably, the continuous compound mixer comprises a plurality of compound mixing sections arranged in continuous succession along the common main axis, each compound mixing section comprising a respective outer cylindrical shell delimiting a respective internal compound mixing chamber.

Preferably, the continuous compound mixer is a one-screw or multi-screw extruder, for example two-screw. Preferably, the continuous compound mixer comprises a central spindle traversing all the internal chambers of the compound mixing sections, coaxially to the internal chambers.

Preferably, each compound mixing section further comprises a respective plurality of lateral spindles housed in the respective internal chamber, arranged around the central spindle and parallel to said central spindle.

Preferably, the continuous compound mixer comprises a fixed central spindle and lateral spindles each of which rotate around a respective axis.

Preferably, the continuous compound mixer is a planetary roller extruder, in which the central spindle is rotatable and the lateral, or planetary, spindles are meshed with the central spindle so that a rotation of the central spindle (by a motor of the continuous compound mixer) triggers, for each planetary spindle, a (counter- rotating motion around an axis thereof and a translation motion along a circular trajectory coaxial to the central spindle. The contact surfaces of the central spindle, of the planetary spindles and of the internal chambers are shaped to allow the meshing of the planetary spindles with the central spindle on the one hand and with the surface of the internal chamber on the other.

Preferably, the continuous compound mixer comprises at least one hopper associated or associable to an inlet in the outer cylindrical shell arranged on an upper portion of said shell. Preferably, said at least one hopper is positioned over the outer cylindrical shell.

The Applicant observed that the extensible arm of the apparatus according to the invention allows to reach all areas of the continuous compound mixer (to pick up or lay down the cylindrical shells) even though it is surrounded by other plant elements, such as hoppers and/or other parts designated to contain and convey the elastomeric materials or other substances into the continuous compound mixer.

The apparatus according to the invention is simple, light, non-cumbersome and inexpensive.

Thanks to the aforementioned characteristics, a single apparatus according to the invention present in a production and/or testing site can be used for intervening on different continuous compound mixers given that such apparatus can be easy to displace, even manually. The Applicant observed that, as regards continuous compound mixers provided with central spindle which remains in place, such as planetary roller extruders, the present invention allows to fit or slip off the cylindrical shells onto or from the central spindle in a precise, quick and simple manner both when disassembling and assembling the continuous compound mixer.

Preferably, the engagement device comprises an elongated element having removable connections arranged at the opposite ends thereof.

Preferably, the removable connections comprise fixing openings arranged at the opposite ends of the elongated element and fixing screws passing through said fixing openings and configured to be engaged in seats obtained on the outer cylindrical shell.

Preferably, a distance between the removable connections is comprised between 80% and 95% of a length of the outer cylindrical shell.

Preferably, the elongated element has an anchoring device arranged substantially half-way between the opposite ends thereof and configured to be removably hung at the end of the extensible arm.

Preferably, the anchoring device is a hole engaged by a hook constrained to the end of the extensible arm.

Preferably, engaging comprises: constraining opposite ends of an elongated element to the outer cylindrical shell by means of removable connections arranged at said opposite ends.

Preferably, engaging comprises: hanging the elongated element at the end of the extensible arm.

Preferably, arranging the elongated element substantially parallel to the main axis of the continuous compound mixer is envisaged.

Preferably, constraining the opposite ends of the elongated element to axially opposite portions of the outer cylindrical shell is envisaged.

Preferably, constraining the opposite ends of the elongated element to the outer cylindrical shell before hanging the elongated element at the end of the extensible arm or after hanging the elongated element at the end of the extensible arm is envisaged.

The Applicant observed that the engagement device described above allows to maintain the outer cylindrical shell substantially stable during displacement. The extended shape thereof allows to constrain it to the axially opposite ends of the cylindrical shell.

The Applicant also observed that the engagement device, given that it can be unconstrained from the shell, is not a hindrance during the operation of the continuous compound mixer.

Preferably, the extensible arm is telescopic.

Preferably, the telescopic extensible arm comprises a number of sections equivalent to the number of outer cylindrical shells of the continuous compound mixer.

Preferably, the telescopic extensible arm comprises at least two, preferably at least three sections.

The telescopic structure allows to reduce the overall dimensions of the arm, in particular during the movement thereof.

Preferably, the extensible arm is mounted on an upper end of the upright.

Preferably, the upright is off-centred with respect to the base.

Preferably, the base, the upright and the extensible arm form a substantially C-like shape delimiting a space, preferably configured for housing part of the continuous compound mixer.

Preferably, the base comprises a support portion of the upright and at least two arms extending moving away from the base and spaced from each other.

Preferably, the two arms delimit - between each other - an angle smaller than 180°, preferably smaller than 90°, preferably equivalent to 60°.

Preferably, the base is configured to move with respect to the ground.

Preferably, the base comprises rollers free to rotate and resting on the ground to allow the displacement of the apparatus, preferably manually.

Preferably, at least one roller is mounted beneath the support portion.

Preferably, at least one roller is mounted at each end of the two arms of the base. Preferably, the extensible arm is motor-driven.

Preferably, a hydraulic pump is operatively connected to the extensible arm to remove it or retract it.

Preferably, the hydraulic pump is manual or motor-driven.

Preferably, adjustment devices for adjusting a height of the extensible arm with respect to the base are envisaged.

Preferably, the adjustment devices are motor-driven. Preferably, the adjustment devices comprise a manual or motor-driven hydraulic pump.

Preferably, the extensible arm has a maximum length comprised between 2400 mm and 2800 mm, more preferably 2650 mm.

Preferably, the extensible arm has a minimum length comprised between 900 mm and 1000 mm, more preferably 950 mm.

Preferably, the extensible arm has a maximum stroke comprised between 1400 mm and 1900 mm, more preferably 1700 mm.

Preferably, a maximum height of the extensible arm with respect to the ground is comprised between 1500 mm and 1700 mm.

Preferably, a minimum height of the extensible arm with respect to the ground is comprised between 1000 mm and 1200 mm.

Preferably, the base extends with respect to the upright and parallel to the extensible arm for a length comprised between 1600 mm and 1800 mm.

Preferably, a ballast is mounted on the base in proximity of the upright.

Preferably, the ballast has a mass comprised between 80 Kg and 100 Kg.

Preferably, a capacity of the apparatus, when the extensible arm is at the maximum length, is comprised between 50 Kg and 200 Kg, more preferably between 90 and 120 Kg, for example 100 Kg.

Preferably, a capacity of the apparatus, when the extensible arm is at the minimum length, is comprised between 600 Kg and 800 Kg, for example 700 Kg. Preferably, during the assembling, arranging the apparatus facing an axial end of the continuous compound mixer, more preferably facing an outlet opening of the continuous compound mixer is envisaged.

Preferably, during assembly, positioning the extensible arm above the continuous compound mixer is envisaged.

Preferably, arranging a part of the base of the apparatus beneath the continuous compound mixer is envisaged.

Preferably, arranging a portion of the continuous compound mixer in the delimited space between the base, the upright and the extensible arm is envisaged.

Preferably, maintaining the base fixed and extending or retracting the extensible arm to displace the outer cylindrical shell along the direction parallel to the main axis is envisaged. Preferably, the continuous compound mixer comprises a central spindle and a plurality of lateral spindles arranged around the central spindle and parallel to said central spindle.

Preferably, displacing the outer cylindrical shell comprises fitting the outer cylindrical shell on the central spindle during the assembly of the continuous compound mixer.

Preferably, displacing the outer cylindrical shell comprises slipping off the outer cylindrical shell from said central spindle during the disassembly of the continuous compound mixer.

Preferably, during disassembly, engaging and displacing the outer cylindrical shells one after the other is envisaged.

Preferably, during disassembly, engaging and removing the outer cylindrical shells from the central spindle one after the other is envisaged.

Preferably, during disassembly, after engaging the outer cylindrical shell to the end of the extensible arm, keeping the outer cylindrical shell suspended prior to displacing it is envisaged.

Preferably, during disassembly, removing or displacing said at least one hopper prior to arranging the apparatus facing the outlet opening of the continuous compound mixer with the extensible arm positioned above the continuous compound mixer is envisaged.

Preferably, during disassembly, removing the lateral spindles from the plant prior to slipping off the outer cylindrical shells from the central spindle is envisaged. Preferably, during assembly, displacing and engaging and fitting the outer cylindrical shells one after the other is envisaged.

Preferably, during assembly, engaging and fitting the outer cylindrical shells onto the central spindle one after the other is envisaged.

Further characteristics and advantages will be more apparent from the detailed description of a preferred but non-exclusive embodiment of a continuous compound mixer and a method for assembling or disassembling a continuous compound mixer according to the present invention.

Description of the drawings

Such description will be outlined hereinafter with reference to the attached drawings, provided solely for by way of non-limiting example, wherein: - figure 1 illustrates an apparatus for assembling or disassembling a continuous compound mixer for polymeric compounds according to the present invention;

- figure 2 illustrates the apparatus of figure 1 associated to a continuous compound mixer in a respective operative step;

- figure 3 illustrates the apparatus of figure 1 associated to the continuous compound mixer in a different operative step;

- figure 4 illustrates an enlarged element of the apparatus according to the previous figures associated to a portion of the continuous compound mixer; - figure 5 is a different view of the element of figure 4;

- figure 6 schematically illustrates a sectional view of a planetary continuous compound mixer.

Detailed description

With reference to figure 1 , an apparatus for assembling or disassembling a continuous compound mixer 2 for elastomeric and/or thermoplastic compounds was indicated in its entirety with 1. The continuous compound mixer 2 and the apparatus 1 are part of a plant for mixing elastomeric and/or thermoplastic compounds. The compound mixing plant may for example comprise several compound mixers 1 and an apparatus 2 for assembling or disassembling said compound mixers 1.

The continuous compound mixer 2 illustrated in figures 3, 4 and 6 is a per se known planetary roller extruder. The continuous compound mixer 2 comprises an outer cylindrical body defined by a plurality of outer cylindrical shells 3a, 3b, 3c, 3d, 3e, ... , 3n (five in the example of figure 2) arranged in continuous succession along a common main axis“X-X”. The outer cylindrical shells 3a, 3b, 3c, 3d, 3e, ... , 3n are removably connected to each other, for example by means of head flanges bolted to each other. Each outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n delimits - therein - an internal chamber which is part of a compound mixing chamber of the continuous compound mixer 2. Each outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n corresponds to a compound mixing section. The continuous compound mixer 2 further comprises a central spindle 4 which traverses all internal chambers, coaxially thereto. Besides the respective outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n, each compound mixing section comprises a plurality of lateral spindles 5 housed in the respective internal chamber, arranged around the central spindle 5 and parallel to said central spindle 5 (figure 6). The central spindle 4 is rotatable and the lateral or planetary spindles 5 are meshed with the central spindle 4 and with a radially internal surface of the compound mixing chambers, so that a rotation of the central spindle 4 (by a motor of the continuous compound mixer, not illustrated) triggers, for each lateral or planetary spindle 5, a counter-rotation motion around an axis thereof and a translation motion along a circular trajectory coaxial to the central spindle 4. The contact surfaces of the central spindle 4, of the lateral spindles 5 and of the internal chambers are shaped to allow the meshing of the lateral spindles 5 with the central spindle 4 on the one hand and with the surface of the internal chamber on the other.

As illustrated in figures 2 and 3, the compound mixing sections and the central spindle 4 extend cantilevered from a protective casing 6 which also contains the motor, not illustrated, and they are supported and spaced from the ground by means of a framework 7. Two of the outer cylindrical shells 3a, 3c are provided with upper openings defining respective inlets connected to respective hoppers 8. The hoppers 8 are thus positioned above the outer cylindrical shells 3a, 3b, 3c, 3d, 3e, ... , 3n. Further raised parts of the plant, designed to contain and convey the elastomeric materials (which form the elastomeric compound) in the hoppers 8, are arranged above the continuous compound mixer 2 (not illustrated). The terminal cylindrical shell 3e, i.e. the one arranged on the opposite side with respect to the protective casing 6, also has an outlet opening, not illustrated, for the compound.

The continuous compound mixer could also be of different type, for example a multi-screw extruder or a compound mixer in which the central spindle is fixed and the lateral spindles rotate each around a respective axis.

The apparatus 1 for assembling or disassembling the continuous compound mixer 2 is a travelling crane comprising a base 9 configured to rest against the ground and move with respect to the ground, an upright 10 mounted on the base, an extensible arm supported by the upright 10, spaced from the base 9 and extending along a substantially horizontal direction with respect to the ground, an engagement device 12 positioned or positionable at one end of the extensible arm 11 and configured for removably engaging an outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n. The base 9 comprises a support portion 13 arranged on which is the upright 10 and two arms 14 extending moving apart from the base 13, parallel to the ground and mutually forming a V-like shape with an angle of about 60°. The base 9 rests against the ground by means of one or more rollers under the support portion 13 and two rollers each mounted at a respective end of each arm 14. The rollers are mounted free to rotate so as to allow the displacement, even manual, of the apparatus 1. Thus, the upright 10 is off-centred with respect to the base 9. In other words, the base 9, the upright 10 and the extensible arm 11 form a substantially C- like shape delimiting a space, preferably configured for housing part of the continuous compound mixer 2 during the assembly or disassembly operations. Furthermore, the base 9 extends with respect to the upright 10 and parallel to the extensible arm 11 for a determined length.

The upright 10 is hinged to the support portion 13 around a horizontal pin. The extensible arm 11 is hinged to an upper end of the upright 10. A substantially vertical hydraulic cylinder 15 is hinged to the base 13 and to the extensible arm 11. The hydraulic cylinder 15 is displaced by a motor-driven oil hydraulic cylinder, not illustrated. The hydraulic cylinder 15 and the pump constitute adjustment devices suitable to adjust a height of the extensible arm 11 with respect to the base 9, i.e. with respect to the ground. For example, a height of the extensible arm 11 with respect to the ground is comprised between 1000 mm and 1700 mm, for a vertical stroke of 700 mm.

The illustrated extensible arm 11 is of the three-sections telescopic type, which are moveable between a fully retracted configuration and a maximum extension configuration. Even the extensible arm is motor-driven and it comprises a motor- driven hydraulic pump operatively connected to said extensible arm 11 so as to displace it between the fully retracted configuration and the maximum extension configuration.

In an embodiment, in the fully retracted configuration, a minimum length of the extensible arm 11 , measured between one end of the extensible arm 11 and a hinging point of the hydraulic cylinder 15 with the arm 11 , is about 950 mm. In the maximum extension configuration, a maximum length of the extensible arm 11 , measured as indicated above, is about 2650 mm. Thus, a maximum stroke of the extensible arm 11 is 1700 mm. A ballast 16 for counter-balancing the weight of the outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n which must be engaged to the end of the extensible arm 11 may be positioned on the base 9, in particular on the support portion 13. For example, the ballast 16 has a mass of 80 Kg.

Thus, the capacity of the apparatus 1 when the extensible arm 11 is at maximum length is about 100 Kg. The capacity of the apparatus 1 when the extensible arm 11 is at minimum length is about 700 Kg.

The dimensions, the capacities and the weights indicated above are provided by way of example. Dimensions, weights and capacities of the apparatus may vary as a function of the dimensions and weights of the continuous compound mixer to be assembled/disassembled.

The engagement device 12 is configured to engage one outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n at a time. The engagement device 12 comprises an elongated element having removable connections arranged at the opposite ends thereof. In the illustrated embodiment (figures 4 and 5), the engagement device 12 comprises a central plate 17 provided with a central hole 18 and two lateral plates 19 integrally joined and orthogonal to the central plate 17, arranged symmetrically with respect to the central plate and each provided with a fixing slot 20.

The presence of the slots allows to adjust the axial position of the engagement device with respect to the shell so as to balance the distribution of the masses of the shell and keep it substantially horizontally when hung at the arm of the apparatus.

The end of the extensible arm 11 comprises a hook 21 and a ring 22 engaged or engageable in the hole 18. Thus, the engagement device 12 is hung at such hook 21 and/or ring 22. Fixing screws 23 pass through the fixing slots 20 and they are configured to be engaged in threaded seats obtained on the outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n. The threaded seats are for example obtained in flanges 24 of each outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n. A distance between the fixing screws 23 or between the slots 20 is comprised between 80% and 95% of a length of the outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n.

In use and according to the method according to the present invention, in order to disassemble the continuous compound mixer 2, for example to carry out cleaning and/or maintenance operations, it is initially envisaged to remove the head cap of the continuous compound mixer 2 and rotate the central spindle 4 so as to remove the lateral screws 5.

Upon removing the lateral screws 5, the apparatus 1 is manually displaced up to bringing to face the outlet opening of the continuous compound mixer 2 with the extensible arm 11 in the retracted configuration, positioned above the continuous compound mixer 2 and substantially parallel to the main axis “X-X” of said continuous compound mixer 2. The base 9 remains at least partly positioned beneath the continuous compound mixer 2 and a portion of the continuous compound mixer 2, such as the end outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n, is positioned in the delimited space between the base 9, the upright 10 and the extensible arm 11.

The hopper/s 8 is/are at least partly removed and displaced to allow the passage of the extensible arm 11.

The engagement device 12 is mounted, by means of the fixing screws 23, on the end outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n. As observable in figure 4, the elongated element is arranged parallel to the main axis“X-X” of the continuous compound mixer 2 and the central plate 17 is parallel to a radially outer surface of the outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n.

The extensible arm 11 is partly removed up to bringing the end hook 21 at the hole 18 of the coupling device 12. Such engagement device 12 is thus engaged to the hook 21.

After having released such outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n from the immediately adjacent one, hanging the outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n by partly raising the extensible arm 11 is envisaged. Subsequently, the extensible arm 11 is retracted and possibly the entire apparatus 1 is displaced backwards up to fully slipping off the outer cylindrical shell 3a, 3b, 3c, 3d, 3e, ... , 3n from the central spindle 4 (figure 2).

Repeating these operations, all outer cylindrical shells 3a, 3b, 3c, 3d, 3e, ... , 3n can be removed one by one and in succession from the central spindle 4.

In order to re-assemble the continuous compound mixer, the operations are carried out in reverse order, by engaging and fitting the outer cylindrical shells 5 onto the central spindle 4 one after the other and then constraining them.