Capping machine for applying capsules on respective containers in aseptic or ultraclean conditions

Abstract

The invention relates to a capping machine comprising a protected area from impurities, an unprotected area divided from the protected area by a parting wall, and an operating unit. The operating unit includes a container support element arranged in the protected area, an operating head arranged in the protected area and configured to apply one capsule on the relative container, a motor assembly arranged in the unprotected area and configured to drive motion of the operating head, a torque control head between the motor assembly and the operating head, and an annular bellows element coaxial with the vertical axis and within the protected area and one opposite axial end crossed in a sealed manner by an output shaft of the torque control head. The torque control head is arranged above the parting wall in the unprotected area and the output shaft crosses said opening and the entire bellows element.

Claims

1. A capping machine (1) for applying capsules (2) on respective containers (3), said machine (1) comprising: a protected area (30) from impurities in which the containers (3) pass; an unprotected area (31) divided from said protected area (30) by a parting wall (22) in such a way that said protected area (30) extends below the parting wall (22) itself; sealing means (22) for separating the protected (30) and unprotected areas (31) from one another; and at least one operating unit (4) configured to perform a capping operation on the containers (3), arranged coaxially to a vertical axis (B) orthogonal to said parting wall (22) and extending in part above said parting wall (22) in the unprotected area (31), in part through an opening (25) of said parting wall (22) and in part below said parting wall in the protected area (30); wherein said operating unit comprises: at least one container support element (6) arranged in the protected area (30) and configured to support one container (3) coaxially to the vertical axis (B); at least one operating head (6) arranged in the protected area (30) and configured to apply at least one capsule (2) on the container (3) hold by the container support element (6); a motor assembly (10) arranged in said unprotected area (31) and configured to drive motion of the operating head (7) along and/or around said vertical axis (B); a torque control head (11) interposed between said motor assembly (10) and said operating head (7) and configured to limit the maximum torque transmitted from the motor assembly (10) to an output shaft (18) coupled to the operating head (7); and an annular bellows element (57, 70) arranged coaxially with said vertical axis (B) and within said protected area (30) and having a first axial end (58, 70a) adjacent to said parting wall (22) and an opposite second axial end (59, 70b) crossed in a sealed manner by said output shaft (18); said bellows element (57, 70) being configured to retract and expand axially following the corresponding movements of said output shaft (18); wherein said torque control head (11) is arranged above said parting wall (22) in the unprotected area (31), and in that said output shaft (18) axially crosses both said opening (25) of said parting wall (22) and the entire bellows element (57, 70).

2. The machine as claimed in claim 1, wherein said output shaft (18) is supported in a free rotary manner within said opening (25) of said parting wall (22) by at least one bearing (56, 65).

3. The machine as claimed in claim 2, wherein said operating unit (4) further comprises a sleeve element (64) coaxially extending through the opening (25) of the parting wall (22), radially supported within said opening (25) by said bearing (65) in a fixed axial position and in a free rotary manner, axially crossed by said output shaft (18) and angularly coupled to the output shaft (18) itself; wherein said output shaft (18) is coupled to said sleeve element (64) in a sliding manner along said vertical axis (B); and wherein said first axial end (70a) of said bellows element (70) is secured in a sealed manner to an edge of the sleeve element (64) arranged within the protected area (30), and said second axial end (70b) of said bellows element (70) is secured in a sealed manner to an outer surface of said output shaft (18).

4. The machine as claimed in claim 3, further comprising an annular gasket (68) mounted at an edge of said opening (25) facing said protected area (30) and cooperating in use in contact with an outer surface of the sleeve element (64) itself.

5. The machine as claimed in claim 2, wherein said operating unit (4) further comprises a tubular slider (54) mounted through said opening (25) of said parting wall (22) in a sliding manner along said vertical axis (B) and protruding from the parting wall (22) itself within said protected area (30); wherein said output shaft (18) is radially supported in a fixed axial position and in free rotary manner within said slider (54) by said bearing (56) and by a further bearing (56) adjacent to a bottom axial end (60) of the slider (54) itself arranged in the protected area; and wherein said first axial end (58) of said bellows element (57) is secured in a sealed manner to an edge of said opening (25) facing said protected area (30), and said second axial end (59) of said bellows element (57) is secured to said bottom axial end (60) of said slider (54).

6. The machine as claimed in claim 5, wherein said operating unit (4) further includes an annular gasket (62) carried by said bottom axial end (60) of the slider (54) and radially cooperating in contact with a portion of said output shaft (18) axially protruding from said slider (54) towards said container support element (6).

7. The machine as claimed in claim 1, wherein said torque control head (11) comprises: an input element (17) connected to a driving mandrel (8) in turn operated by said motor assembly (10); said output shaft (18); and a magnetic clutch (45) for transmitting angular motion about said vertical axis (B) from said input element (17) to said output shaft (18).

8. Machine according to claim 1, comprising: a plurality of operative units (4) having respective said vertical axis (B) and angularly spaced from each other around a central axis (A) parallel to said vertical axes (B); and a driving shaft (5) coaxial to said central axis (A) and angularly connected to the operating units (4) and to said parting wall (22); wherein said driving shaft (5), said parting wall (22) and said operating units (4) define a rotational part (26) of said machine (1) cooperating with a fixed part (27) of the machine 1 itself arranged in a radially outermost position; and wherein sealing means (22) are provided between said rotational part (26) and said fixed part (27).

9. The machine as claimed in claim 8, wherein said sealing means (22) comprise a fixed annular channel (33), associated with said fixed part (27) and partially filled with a sterile liquid, and an annular element (34) associated with the rotating part (26), coaxial with the annular channel (33) and rotatable in use in the liquid of the annular channel (33).

10. The machine as claimed in claim 1, in which the said protected area is a sterile area (30).

11. The machine as claimed in claim 2, wherein said torque control head (11) comprises: an input element (17) connected to a driving mandrel (8) in turn operated by said motor assembly (10); said output shaft (18); and a magnetic clutch (45) for transmitting angular motion about said vertical axis (B) from said input element (17) to said output shaft (18).

12. The machine as claimed in claim 3, wherein said torque control head (11) comprises: an input element (17) connected to a driving mandrel (8) in turn operated by said motor assembly (10); said output shaft (18); and a magnetic clutch (45) for transmitting angular motion about said vertical axis (B) from said input element (17) to said output shaft (18).

13. The machine as claimed in claim 4, wherein said torque control head (11) comprises: an input element (17) connected to a driving mandrel (8) in turn operated by said motor assembly (10); said output shaft (18); and a magnetic clutch (45) for transmitting angular motion about said vertical axis (B) from said input element (17) to said output shaft (18).

14. Machine according to claim 2, comprising: a plurality of operative units (4) having respective said vertical axis (B) and angularly spaced from each other around a central axis (A) parallel to said vertical axes (B); and a driving shaft (5) coaxial to said central axis (A) and angularly connected to the operating units (4) and to said parting wall (22); wherein said driving shaft (5), said parting wall (22) and said operating units (4) define a rotational part (26) of said machine (1) cooperating with a fixed part (27) of the machine 1 itself arranged in a radially outermost position; and wherein sealing means (22) are provided between said rotational part (26) and said fixed part (27).

15. Machine according to claim 3, comprising: a plurality of operative units (4) having respective said vertical axis (B) and angularly spaced from each other around a central axis (A) parallel to said vertical axes (B); and a driving shaft (5) coaxial to said central axis (A) and angularly connected to the operating units (4) and to said parting wall (22); wherein said driving shaft (5), said parting wall (22) and said operating units (4) define a rotational part (26) of said machine (1) cooperating with a fixed part (27) of the machine 1 itself arranged in a radially outermost position; and wherein sealing means (22) are provided between said rotational part (26) and said fixed part (27).

16. Machine according to claim 4, comprising: a plurality of operative units (4) having respective said vertical axis (B) and angularly spaced from each other around a central axis (A) parallel to said vertical axes (B); and a driving shaft (5) coaxial to said central axis (A) and angularly connected to the operating units (4) and to said parting wall (22); wherein said driving shaft (5), said parting wall (22) and said operating units (4) define a rotational part (26) of said machine (1) cooperating with a fixed part (27) of the machine 1 itself arranged in a radially outermost position; and wherein sealing means (22) are provided between said rotational part (26) and said fixed part (27).

17. The machine as claimed in claim 2, in which the said protected area is a sterile area (30).

18. The machine as claimed in claim 3, in which the said protected area is a sterile area (30).

19. The machine as claimed in claim 4, in which the said protected area is a sterile area (30).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] A non-limiting embodiment of the present invention will be described hereafter by way of example with reference to the accompanying drawings, in which:

[0039] FIG. 1 schematically shows a partially-sectioned perspective view, with parts removed for clarity, of a capping machine in accordance with the teachings of the present invention;

[0040] FIG. 2 is a larger-scale section along line II-II of FIG. 1, with parts removed for clarity; and

[0041] FIG. 3 is a section analogous to FIG. 2 and relative to a possible variant of the capping machine of FIGS. 1 and 2.

BEST MODE FOR CARRYING OUT THE INVENTION

[0042] With reference to FIGS. 1 and 2, number 1 indicates as a whole a capping machine configured to apply threaded or non-threaded capsules 2 (FIG. 2) on respective containers 3, in particular bottles, in aseptic or ultraclean conditions.

[0043] The machine 1 comprises a plurality of stations or operating units 4 configured to perform respective capping operations on the containers 3 and arranged equally spaced angularly about a vertical central axis A.

[0044] The operating units 4 are also rotatable about the central axis A and receive the containers 3 to be closed by an input star wheel (known per se and not shown); the closed containers 3 are then released to an output star wheel (also known per se and not shown) arranged in a position adjacent to the input star wheel.

[0045] The operating units 4 are angularly connected to a driving shaft 5 coaxial to central axis A.

[0046] In particular, each operating unit 4 (FIGS. 1 and 2) presents a vertical axis B parallel to the central axis A and comprises: [0047] a container support element 6 configured to receive a relative container 3 arranged vertically, i.e. with its own axis C parallel to the axis A and coaxial with the respective axis B; [0048] an operating head 7 coaxially arranged above the relative container 3 to apply one capsule 2 on the container 3 itself hold by the container support element 6; [0049] a driving mandrel 8 (known per se and only partially shown in FIGS. 1 and 2) coaxial with the relative axis B and configured to drive motion of the operating head 7 along and around the axis B itself; [0050] a motor assembly 10 (FIG. 2) for imparting a roto-translational motion to the driving mandrel 8 along and around the respective axis B; and [0051] a torque control head 11 interposed between the driving mandrel 8, or the motor assembly 10, and the operating head 7 and configured to limit the maximum torque transmitted from the driving mandrel 8, or the motor assembly 10, to the operating head 7.

[0052] In particular, in the example shown, the container support element 6 of each operating unit 4 includes a resting plate 12 extending orthogonally to the relative axis B and configured to receive, on its top surface, one respective container 3.

[0053] As a possible alternative not shown, each container support element 6 may include a gripping element supporting the relative container 3 at its top portion or neck in a suspended way.

[0054] Each container support element 6 is configured to limit axial and rotational movements of the relative container 3.

[0055] The operating head 7 of each operating unit 4 includes a gripping member 13 (FIG. 2) configured to coaxially grip threaded or non-threaded capsules 2 that are to be screwed or applied on the tops of containers 3.

[0056] Each driving mandrel 8 is only shown limited to a driving portion 15 directly connected to the respective torque control head 11 and selectively moved, in a way known per se and not shown, by the relative motor assembly 10 along and around its axis B.

[0057] Driving portion 15 of each driving mandrel 8 has, at its end connected to the relative torque control head 11, a head recess 16, whose function will be clarified hereafter.

[0058] With particular reference to FIG. 2, each torque control head 11 has an input element 17, directly connected to the driving portion 15 of the relative driving mandrel 8, and an output shaft 18 extending coaxially to the relative axis B and connected at its free end to the respective operating head 7.

[0059] Each output shaft 18 is rotatable about the relative axis B and can translate along this axis under the action of the respective motor assembly 10 and driving mandrel 8, so as to cause a corresponding rotation of the respective operating head 7 and a corresponding translation thereof to and away from the respective container 3 and, therefore, to and away from the respective container support element 6.

[0060] As can be seen in FIGS. 1 and 2, the motor assemblies 10, each of which comprises in addition to the actual motor also transmission gears, bearings, cam elements (all known per se and not shown), etc., and the driving mandrels 8 are housed in a drum casing 20 surmounting the driving shaft 5 and radially cantilevered with respect to the latter.

[0061] More specifically, the drum casing 20 is delimited by a cylindrical side wall 21 closed, at its lower end, by a discoidal bottom head wall 22 and, at its upper end, by a discoidal top head wall 23 facing the bottom head wall 22.

[0062] As shown in FIG. 1, bottom head wall 22 of drum casing 20 is secured to an annular flange 24 of the upper end of the driving shaft 5.

[0063] Advantageously, even the torque control heads 11 are housed in the drum casing 20, whilst the output shafts 18 extend, in a sealed manner, through respective openings of the bottom head wall 22 of the drum casing 20 itself so as to project downwards from the latter along with the respective operating heads 7.

[0064] In practice, the driving shaft 5, the drum casing 20 and the operating units 4 define a rotational part 26 of the machine 1 cooperating with a fixed part 27 of the machine 1 itself arranged in a radially outermost position.

[0065] In the case shown in FIG. 1, the fixed part 27 comprises an annular platform 28 extending around the drum casing 20 and approximately at the same height as, or slightly below, the bottom head wall 22 of the drum casing 20 itself.

[0066] As can be seen in FIGS. 1 and 2, the bottom head wall 22 of the casing 20 and the annular platform 28 delimit in the lower part a process environment, or more precisely a closed environment for the containers 3, which is isolated from the external environment and kept in sterile or ultraclean conditions (i.e. protected from impurities) and in slight overpressure.

[0067] This closed environment therefore defines a protected or sterile atmosphere area 30 of the machine 1, in which the containers 3 carried by the respective container support elements 6 pass.

[0068] The entrance of the containers 3 to be capped and the exit of the containers 3 in the capped form in/from the protected or sterile atmosphere area 30 is permitted through suitable openings (not shown) in the lateral bounding walls (known per se and not shown) of this area.

[0069] The environment located above the annular platform and the bottom head wall 22 of the drum casing 20 defines instead an unprotected or non-sterile atmosphere area 31 of the machine 1.

[0070] The protected or sterile atmosphere area 30 and the unprotected or non-sterile atmosphere are 31 are separated from each other by sealing means 32. In the present case, the sealing means 32 comprise a fixed annular channel 33, associated with the fixed part 27 and partially filled with a sterile liquid, and an annular element 34 associated with the rotating part 26, coaxial with the annular channel 33 and rotatable in use in the liquid of the annular channel 33 itself.

[0071] In particular, the annular channel 33 extends in overhang towards the axis A from the radially innermost edge of the annular platform 28.

[0072] The annular element 34 is instead defined by a downward annular extension of the side wall 21 of the drum casing 20, projecting in a cantilevered manner from the bottom head wall 22. The annular element 34 can be partially immersed in the liquid of the annular channel 33 and moves inside the annular channel 33 itself dragged by the rotation of the drum casing 20.

[0073] The sterile liquid, which is preferably a bacteriostatic liquid, that is capable of eliminating any bacteria, for example a solution of water and chlorine, acts as an insulator preventing the contact between the protected or sterile atmosphere area 30 and the surrounding external environment.

[0074] Due to the slight overpressure inside the protected or sterile atmosphere area 30, a difference in level (of a few mm of water and equal to the overpressure created) is formed between the liquid present in the annular channel 33 located in contact with the sterile or protected atmosphere area 30 and the one located outside the annular element 34 in contact with the external environment.

[0075] With particular reference to FIG. 2, the input element 17 of the torque control head 11 of each operating unit 4 comprises: [0076] a tubular element 35 coaxial with the respective axis B and having a top portion partially engaging, in a sliding manner, the head recess 16 of driving portion 15 of the respective driving mandrel 8; and [0077] a substantially cup-shaped bushing element 36 having a cylindrical side wall 37, externally and coaxially coupled to a bottom portion of the tubular element 35, and a head wall 38 connected to a bottom annular edge of side wall 37 and axially facing the head recess 16.

[0078] In particular, each tubular element 35 has a plurality of external longitudinal slots 39, which are parallel to axes A, B and are equally spaced angularly about the relative axis B. The slots 39 are coupled, in a sliding manner parallel to axes A, B, with respective pins 40 radially protruding towards the axis B itself from the side walls of the driving portion 16 of the relative driving mandrel 8 delimiting the relative head recess 16. This arrangement allows limited movements of the tubular element 35 of each torque control head 11 along the relative axis B with respect to the driving portion 15 of the relative driving mandrel 8. These axial movements are controlled by a cylindrical helical spring housed within the relative tubular element 35 and axially interposed between a head wall of the relative head recess 16 and an intermediate annular shoulder 42 radially protruding inwards from the lateral wall of the tubular element 35 itself. Thanks to the presence of the springs 41, it is possible to cushion the impact of the operating heads 7 onto the containers 3 to be capped.

[0079] Each bushing element 36 is angularly and axially coupled to the relative tubular element 35. Since the side wall 37 of the bushing element 36 is internally threaded and engages an outer thread provided on a bottom portion of the tubular element 35, it is possible to adjust in known manner the axial relative position between the bushing element 36 and the tubular element 35. The aim of this function will be explained later on.

[0080] The output shaft 18 of each torque control head 11 has a top portion 18a housed within both the relative tubular element 35 and the relative bushing element 36 and crosses the relative head wall 38 at a through central opening 43 thereof so as to protrude axially from the head wall 38 itself towards the relative operating head 7 and the bottom head wall 22 of drum casing 20.

[0081] The top portion 18a of each output shaft 18 is coupled to the relative tubular element 35, and therefore to the relative driving mandrel 8, by a magnetic clutch 45.

[0082] In particular, the top portion 18a of each output shaft 18 is mounted within the relative tubular element 35 and the relative bushing element 36 in an angularly free manner about the relative axis B and is supported by the tubular element 35 itself by means of a bearing 46, in particular a ball bearing.

[0083] In the example shown, each magnetic clutch 45 includes a top magnet 47, shaped preferably like an annular disk and carried by the top portion 18a of the relative output shaft 18, and a bottom magnet 48, also shaped preferably like an annular disk, carried by the head wall 38 of the relative bushing element 36 and arranged at a given distance along the relative axis B from the top magnet 47.

[0084] The axial distance between each pair of top and bottom magnet 47, 48 defines the maximum torque transmitted by means of the magnetic clutch 45 from the relative tubular element 35 to the relative output shaft 18.

[0085] The value of the maximum torque transmitted from the input element 17 of each torque control head 11 to the relative output shaft 18 can be adjusted by changing the axial distance between the relative top and bottom magnets 47, 48; in particular, this adjustment can be carried out by screwing or unscrewing the relative bushing element 36 on the relative tubular element 35.

[0086] As visible in FIGS. 1 and 2, each output shaft 18 further includes a main portion 18b, extending, in a sealed manner, through the relative opening 25 of bottom head wall 22 of drum casing 20 and within the protected or sterile atmosphere area 30; each output shaft 18 further includes a bottom portion 18c directly connected to the relative operating head 7.

[0087] In particular, in the example of FIGS. 1 and 2, bottom head wall 22 further includes, for each operating unit 4, a sleeve element 50 mounted through the relative opening 25 and having an end annular flange 51 secured by screws 52 to the bottom head wall 22 itself on the side thereof arranged inside drum casing 20 and facing top head wall 23.

[0088] Each sleeve element 50 presents, at its radially inner surface, a plurality of longitudinal slots 53 parallel to axes A, B and configured to allow longitudinal axial displacements of the relative output shaft 18 along its axis B, as it will be described in further detail hereafter.

[0089] As a possible alternative not shown, longitudinal slots 53 may be directly formed on the inner delimiting surface of the relative opening 25 of the bottom head wall 22.

[0090] In the example shown in FIGS. 1 and 2, each operating unit 4 also comprises a tubular slider 54 mounted radially interposed between the relative sleeve element 50 and the main portion 18b of the relative output shaft 18. The slider 54 is provided with longitudinal projections 55 radially protruding from the slider radially outer surface and engaging, in a sliding manner parallel to the relative axis B, the respective longitudinal slots 53. Interaction of longitudinal projections 55 with the respective longitudinal slots 53 allows guiding translational movements of the sliders 54 along their axes B.

[0091] The main portion 18b of each output shaft 18 extends through the respective slider 54 and is coupled to the slider 54 itself in a fixed axial position and in a free rotary manner. In particular, the main portion 18b of each output shaft 18 is supported within the relative slider 54 by a pair of bearings 56, preferably by ball bearings.

[0092] In order to seal axial movements of each slider 54 within the protected or sterile atmosphere area 30, the relative operating unit 4 also includes an annular bellows element 57. In particular, the bellows element 57 has one axial end 58, secured in a sealed manner to bottom head wall 22 of drum casing 20, and one opposite axial end 59 secured in a sealed manner to a bottom axial end 60 of the slider 54. The bellows element 57 is formed in a known manner by a plurality of interconnected frustoconical rings 61 with alternate conicalness. The rings 61 can be folded onto each other to define a retracted minimum axial length of the bellows element 57 or can be axially expanded to define an expanded maximum axial length of the bellows element 57 itself.

[0093] In this way, any axial movement of each slider 54 and the relative output shaft 18 are followed by retraction or expansion of the corresponding bellows element 57.

[0094] Rotational movements of each output shaft 18 with respect to the relative slider 54 are sealed by an annular gasket 62 carried by the bottom axial end 60 of the slider 54 itself at its bottom mouth. In particular, each gasket 62 has an annular lip 63 cooperating in contact with or scraping against the bottom portion 18c of the relative output shaft 18.

[0095] In use, the containers 3, already filled with a pourable product, are loaded onto the respective container support elements 6 and moved by these around the axis A.

[0096] During this rotation, the operating units 4 perform the operations of applying the capsules 2 on the respective containers 3.

[0097] In particular, each operating head 7 is moved axially along, and is rotated about, the relative axis B by the relative motor assembly 10 and driving mandrel 8 while the operating head 7 itself rotates together with the driving shaft 5 around the axis A.

[0098] For the sake of clarity, the following description will be referred to one single operating unit 4 acting on one single container 3 for applying one relative capsule 2; it is evident that the same sequence of steps applies to any other operating unit 4 for performing the capping operation of the respective container 3.

[0099] When the container 3 to be capped is located below the operating head 7 provided with the capsule 2 to be applied, an axial movement along axis B towards the container 3 itself is imparted by motor assembly 10 and driving mandrel 8 to the input element 17 of torque control head 11. The same axial movement is transmitted to the output shaft 18 and slider 54 as well as to the operating head 7. As the operating head 7 contacts the container 3, the spring 41 is compressed with a relative axial movement of the input element 17, output shaft 18 and slider 54 with respect to the driving portion 15 of driving mandrel 8. This relative axial movement is allowed by sliding engagement between slots 39 and pins 40 and permits to cushion contact between the operating head 7 and the container 3.

[0100] In general, during any axial movement, the seal between the protected or sterile atmosphere area 30 and the unprotected or unsterile atmosphere area 31 is achieved by bellows element 57 that retracts or expands following the axial movements of the output shaft 18 and the relative slider 54 towards and away from the bottom head wall 22.

[0101] After contact between the operating head 7 and the container 3, a roto-translational movement with respect to axis B is imparted by motor assembly 10 and driving mandrel 8 to input element 17 of torque control head 11. This movement is transmitted to the output shaft 18 and therefore to the operating head 7 by magnetic clutch 45 and produces screwing of the capsule 2 on the container 3. At the end of the stroke of the capsule 2, further rotation of the capsule 2 itself requires to overcome the resistance torque exerted by the container 3. As such resistance torque exceeds the maximum torque that can be transmitted to the output shaft 18 by the magnetic clutch 45, a relative rotation between top and bottom magnets 47, 48 occurs, so avoiding to force the capsule 2 on the container 3 with possible damages to their threads.

[0102] Following completion of the capping operation, the operating head 7, the output shaft 18, the slider 54 and the input element 17 are moved axially away from the capped container 3, so permitting release thereof from the capping machine 1.

[0103] The advantages of the capping machine 1 as shown in FIGS. 1 and 2 are clearly evident from the foregoing description.

[0104] In particular, this solution permits to minimize the number of gaskets and seals necessary to isolate the parts of each operating unit 4 housed within the protected or sterile atmosphere area 30, while maintaining the same functionality as that of known operating units. In fact, in the present case, only one annular gasket 61 and one annular bellows element 57 are sufficient to guarantee the necessary sealing between each operating unit 4 and the protected or sterile atmosphere area 30.

[0105] It should be also noted that each output shaft 18 is well radially supported up to the zone close to the relative operating head 7.

[0106] In addition, thanks to the fact that the torque control head 11 of each operating unit 4 is arranged above the bottom head wall 22 and therefore outside the protected or sterile atmosphere area 30, the size of this latter area and the possible points of contamination can be minimized. Moreover, it is possible to use a regular torque control head instead of an aseptic one.

[0107] Furthermore, in a bottling plant operating in sterile or ultraclean conditions, the roof part (i.e. the bottom head wall 22) of the protected or sterile atmosphere area 30 of the capping machine 1 can be arranged at the same height as the corresponding roof part of the protected or sterile atmosphere area of adjacent filling machine.

[0108] The variant of FIG. 3 only differs from the solution of FIGS. 1 and 2 in the way in which each output shaft 18 extends in a sealed manner through the relative opening 25 of the bottom head wall 22 of drum casing 20 within the protected or sterile atmosphere area 30.

[0109] In particular, in this case, the main portion 18b of each output shaft 18 is angularly coupled to an outer sleeve element 64, in turn mounted in a fixed axial position and in a free rotary manner within the relative through opening 25 of the bottom head wall 22 of drum casing 20. More specifically, each sleeve element 64 is supported within the relative opening 25 by a bearing 65, in particular by a ball bearing.

[0110] Each sleeve element 64 is also provided with a plurality of longitudinal grooves 66 parallel to axes A, B and configured to be engaged in a sliding manner in use by respective radial projections 67 of the main portion 18b of the relative output shaft 18.

[0111] In this way, each output shaft 18 is able to translate axially along its axis B with respect to the relative sleeve element 64 and is also adapted to rotate about such axis B together with the sleeve element 64 itself with respect to bottom head wall 22 of drum casing 20.

[0112] Sealing of the rotational movement of the assembly formed by the main portion 18b of each output shaft 18 and the relative sleeve element 64 with respect to bottom head wall 22 of drum casing 20 is achieved by an annular gasket 68 mounted at the bottom edge of the relative opening 25 and cooperating in use in contact with an outer surface of the sleeve element 64 itself.

[0113] Sealing of the translational movement of each output shaft 18 from the unprotected or unsterile atmosphere area 31 to the protected or sterile atmosphere area 30 and vice versa is achieved by an annular bellows element 70, similar to bellows element 57 and not further described hereafter, having its top axial end 70a, secured in a sealed manner to a bottom edge of the relative sleeve element 64, and its bottom axial end 70b, secured in a sealed manner to the main portion 18b of the output shaft 18 itself proximate to the bottom portion 18c.

[0114] The advantages of the solution of FIG. 3 are the same as achieved by the solution of FIGS. 1 and 2 and will not be repeated for the sake of conciseness.

[0115] In addition, in the solution of FIG. 3, no bearing is present within the protected or sterile atmosphere area 30 (the only bearing present is located within the opening 25 of bottom head wall 20).

[0116] Clearly, changes may be made to capping machine 1 as described herein without, however, departing from the scope of protection as defined in the accompanying claims.