Capping head for applying screw caps to containers, especially within an aseptic space

Abstract

A capping head (201) is provided, intended for applying screw caps to containers, wherein, to obviate the hyperstaticity of a guide and support structure for rototranslating shafts (13, 14, 15, 16) imparting to the caps the rototranslational movements necessary for capping, a torsionally rigid compensating joint (220) is provided between coupling members (12), transmitting the movements generated by a driving system (10) to cap-handling members (11), and said cap-handling members (11) adapted to perform movements, said compensating joint (220) being adapted to perform relative movements of angular misalignment and parallel misalignment to recover angular and planar offset errors of the shafts (16, 14) connected to each other by said joint (220) relative to the axis of a container. Preferably, the capping head (201) is intended to operate on containers located within an aseptic space and is of a type in which the driving system (10) and the coupling members (12) are arranged outside the aseptic space.

Description

[0001] “Capping head for applying screw caps to containers, especially within an aseptic space ”

[0002] DESCRIPTION

[0003] Technical Field

[0004] The present invention relates to capping plants, and more particularly it relates to a capping head for applying screw caps to containers, such capping head being intended in particular for operating on containers located within an aseptic space.

[0005] The invention further relates to a capping machine comprising one or more of such capping heads.

[0006] Background Art

[0007] Capping heads are devices that make it possible to apply a cap or seal to the mouth of containers such as bottles, small bottles, etc. They are usually employed in capping assemblies or capping machines generally comprising a movable support which moves a plurality of said heads following a path along which the containers are also conveyed. For example, the capping heads are mounted on the periphery of a support that is rotated to sequentially bring the containers and the capping heads to a capping position. During their displacement, the capping heads are subjected to a vertical downward translational movement to reach the position of the mouth of the container to be capped and to lift again once capping is completed. Furthermore, in case of application of screw caps, the capping heads are also rotated to tighten the cap onto the mouth of the container, and the translational movement also serves to apply a compensating axial load (top load) necessary to keep the container firmly held during the capping operation.

[0008] In the capping heads intended for foodstuff industry, it is necessary to guarantee high hygienic conditions in the capping area. In particular, it is necessary to isolate the area of cap application, which must be aseptic, from the motion-transmitting area, in order to prevent traces of contaminants that may be present in said motion-transmitting area from reaching the aseptic area.

[0009] In case of capping heads intended for applying screw caps, both the cap-handling members and the coupling members, which transmit to the cap-handling members the rotational and translational movements generated by a driving system and essentially comprise clutch means for controlling the torque applied to a cap and elastic means for applying the axial load, are arranged within the capping area. The cap-handling members and the coupling members are thus directly coupled to each other.

[0010] This arrangement has the serious drawback that, after an adjustment is made to the clutch means or elastic means, which involves accessing the aseptic area, it is necessary to carry out a cycle of washing and sanitization of said area, this resulting in interruption of machine operation for even quite long periods of time.

[0011] To overcome this drawback, it has been proposed to arrange the coupling members outside the aseptic area, leaving therein only the cap-handling members. A capping head of this type is disclosed in WO 2020 / 249286 Al. As a result of the separation between the coupling members and the cap-handling members, there is provided an additional shaft to connect said members to each other, which shaft extends through the entire aseptic area and is enclosed throughout its extension in a bellows-like element which isolates it from the aseptic space inside which capping takes place.

[0012] The main problem with this solution is hyperstaticity. Indeed, to keep proper alignment of the various rototranslating shafts transmitting the rototranslational motion to the cap, said shafts are supported by a plurality of bearings received on bushings rigidly connected to parallel support flanges which are integral to the frame of the capping machine and on which the rototranslating shafts are also centered. The various bearings are thus associated to different elements of the capping head (in particular, to the clutch means and the cap-handling means) and the two support flanges are also provided on different elements of the frame of the capping machine: this makes it technically impossible to guarantee perfectly aligned centering of the outer rings of the bearings and perfect parallelism of the support flanges. The more position and parallelism errors grow, the more strain, deformation and unwanted wear and tear, which are detrimental to the useful life of the system and the extent and adverse effects of which are unquantifiable, or at least hardly quantifiable, in the design phase, are generated in the capping head.

[0013] As is well known to the person skilled in the art, a hyperstatic structure does not allow these position and parallelism errors to be recovered. In addition, it is inherently expensive.

[0014] The cited document also shows an embodiment in which the problem of hyperstaticity is overcome by eliminating the bearings associated with the cap-handling members. However, also in this solution, given the overall length of the rototranslating shafts and the distance of the clutch means from the bearings, the offset of the cap-handling members from the correct alignment with the container would almost certainly be excessive.

[0015] To recover angular and planar offset errors between shafts of a hyperstatic structure, it is known to connect these shafts by means of compensating joints, the structure of which will depend on the kind of movements that the connected shafts will have to perform.

[0016] In particular, the Applicant has already proposed a compensating joint to be used in a capping head of the type described in WO 2020 / 249286 Al. This joint is a torsionally rigid joint allowing relative motions of angular misalignment and parallel misalignment between the shafts connected by the joint itself while preventing axial displacements that might alter the axial load imparted by the elastic elements of the capping head, and it is arranged between the driving system and the coupling members.

[0017] This arrangement has given rise to a number of problems in use. In fact, because of the location of the joint, the coupling members, during rotation, exhibit remarkable radial oscillation, due to the fact that they are guided axially only by the shaft connecting them to the cap-handling members, which shaft has a reduced diameter in order to keep inertia low. The joint, in turn, is forced to compensate for angular displacements and misalignments significantly larger than those given by flange alignment errors alone: its operation is not always smooth and uniform but, instead, often runs jerkily. Moreover, the repeatability of the axial load actually transmitted to the caps has proven to be poor, with a wide range of fluctuation.

[0018] Summary of Invention

[0019] The object of the present invention is to provide a capping head that overcomes the prior art problems set forth above.

[0020] The object is achieved with a capping head for applying screw caps to containers which is equipped with a compensating joint adapted to obviate the hyperstaticity of a guiding and supporting structure for the rototranslating shafts transmitting the rototranslational movements to the cap-handling members, wherein the compensating j oint is arranged between an output shaft of coupling members that transmit a torque and axial load from the driving system to the caphandling members, and an input shaft of said cap-handling members.

[0021] Preferably, the capping head is intended to operate on containers situated within an aseptic space and is of a type in which the driving system and the coupling members are located outside said aseptic space.

[0022] Advantageously, to reduce the overall mass of the joint, the elements thereof intended for coupling to the shafts are formed by a pair of elongated parallel horizontal plates, the longitudinal dimensions of which are respectively oriented along the directions in which radial movements of the joint intended to recover offset errors take place, and a pair of vertical plates, attached each to one of said horizontal plates and acting as supports for means allowing said radial movements.

[0023] The plates are made of lightweight metal material, preferably aluminum, or plastics.

[0024] A further object of the invention is a capping machine comprising one or more of said capping heads.

[0025] Brief Description of Drawings These and other features and advantages of the present invention will become evident from the following description of preferred embodiments given by way of non-limiting example with reference to the annexed drawings, in which elements indicated by the same or similar reference numbers denote elements having the same or similar functionality and construction, and wherein: Fig.1 is a schematic isometric view of a known capping head having a compensating j oint; Fig.2 is a schematic view of the capping head of Figure 1, in axial section;

[0026] Fig.3 is an enlarged partial view of the capping head of Figure 1;

[0027] Fig.4 is a further enlarged isometric view of a compensating j oint used in the capping head of Figures 1 - 3;

[0028] Fig.5 is a view similar to Figure 3, showing a capping head according to the invention; and Fig.6 is a view similar to Figure 4, showing the compensating j oint used in the capping head of Figure 5.

[0029] Description of Embodiments

[0030] To facilitate understanding of the invention, the structure of the capping head disclosed in WO 2020 / 249286 Al will be briefly described with reference to Figures 1 - 3 thereof. For details, reference is made to said document.

[0031] The capping head, indicated as a whole with 1, essentially comprises: a driving system 10 generating the rotational and translational movements necessary for capping, cap-handling members (cone-shaped cap chuck) 11 controlled by the driving system 10; and coupling members 12, transmitting the movements from the driving system 10 to the caphandling members 11 and essentially comprising clutch means (in particular, a magnetic clutch) to control the torque applied to a cap, and elastic means to apply a predetermined axial load to the cap.

[0032] Motion is transmitted from the driving system 10 to the cone-shaped cap chuck 11 through rototranslating shafts, in particular, a shaft 13 for connecting the driving system 10 to the coupling members 12, and shaft 14 for connecting the coupling members 12 to the cap-handling members 11. As mentioned, the presence of the latter shaft is made necessary by the separation between the coupling members 12 and the cap-handling members 11 resulting from the arrangement of the coupling members 12 outside the aseptic area. The shaft 14 is located in the aseptic area and is thus properly isolated from the surrounding environment. The isolating means are not explicitly indicated.

[0033] Furthermore, input and output shafts of the clutch means are indicated with 15 and 16, respectively.

[0034] The capping head 1 is part of a capping machine 100, for example of the turret type, which carries a plurality of capping heads 1 and has a carrying frame (parts 110 of which can be seen) comprising, among other things, flanges 102, 103 forming the support for the driving system 10 and the shaft 14, respectively, and the cap-handling members 11. To guarantee perfect alignment of the capping axis defined by the various shafts with a container to be capped, there are provided a pair of bearings (not shown in the drawings) received on bushings attached to the supporting flanges 102, 103, on which the additional shaft 14 is also centered.

[0035] For the sake of completeness, the means causing the downward axial translational movements of the capping head 1 and the rotational movements about the axis of said head. Here, said means are of the mechanical type and are formed by a drum cam 104 cooperating with cam follower rollers carried by a shaft of the driving system 10 and a gear assembly 105, respectively. Of course, the translation and rotation of the capping head 1 could be obtained by using respective actuators, such as electric motors. Means for separating the aseptic area of the capping machine 100 from the non-aseptic area are not shown, as they are not necessary for the understanding of the invention.

[0036] To obviate the hyperstaticity of the structure for supporting and aligning the shafts, in the past the Applicant proposed to install, between the driving system 10 and the coupling members 12 of the capping head 1, therefore between the shaft 13 and the shaft 15, a torsionally rigid compensating joint 20 adapted to allow relative movements of angular misalignment and parallel misalignment between the shafts connected thereto while preventing axial displacements which could alter the axial load applied by the elastic means of the coupling members 12.

[0037] The joint 20 developed by the Applicant for this purpose is shown in Figure 4. The joint 20 has a substantially cylindrical body obtained by joining a pair of parts 20a, 20b, also substantially cylindrical, intended to be coupled to the shafts 13, 15, respectively, for example, by means of threaded engagement. The means enabling the movements necessary to compensate for the misalignments of the shafts are formed by a pair of pins 21 having orthogonal axes and advantageously made of steel, which slide on respective bushings 22 advantageously made of sintered bronze.

[0038] However, any other solution obviating hyperstaticity and allowing radial sliding and axial rotation of the shafts connected by the joint 20 in Fig. 4 can be adopted instead of said joint. A commercial joint suitable for this purpose is, for example, the Loewe GK joint manufactured by Schmidt-Kupplung GmbH in Wolfenbiittel (Federal Republic of Germany). Due to the fact that the joint 20 is arranged upstream of the coupling members 12, the inertia it introduces is not relevant in the context of capping. Therefore, the cylindrical body of the joint has been made of stainless steel and with relatively large dimensions, made necessary by the features of the shaft 13 of the capping head 1.

[0039] This solution has given rise, in use, to the problems discussed above, which are solved according to the invention by the capping head 201 and the joint 220 shown in Figures 5, 6. For the sake of simplicity, only the differences from the solution employing the joint 20 will be described.

[0040] According to the invention, the compensating joint 220 is now arranged between the coupling members 12 and the cap-handling members 11, and more precisely between the output shaft 16 of the clutch means and the shaft 14, as can be seen in Figure 5.

[0041] As the j oint 220 is now located under the magnetic clutch and is therefore directly associated with the cap-handling members 11, its dynamic behavior directly affects the capping process and the quality thereof. In particular, the inertia it introduces becomes relevant, as high inertia would worsen performance. Therefore, even if the functional structure of the joint 220 is substantially identical to the one of the joint 20 of Figure 4, the component has been redesigned to accommodate the requirements of reduced inertia, while maintaining the same requirements for strength and uniformity in torque transfer.

[0042] In particular, the two substantially cylindrical parts 20a, 20b, of the known joint are replaced with a pair of elongated parallel horizontal plates 223a, 223b with their longitudinal dimensions parallel to the axis of one of the pins 221, and the pins 221 and the bushings 222 are carried by respective vertical support plates 224a, 224b attached to the plates 223a, 223b, respectively. Said plates 223a, 223b further have axial attachments 225a, 225b, which, for example, are internally threaded, for being coupled to the respective shaft 16 or 14 (Figure 5). The plates 223a, 223b and the support plates 224a, 224b are made of lightweight material, in particular aluminum, whereas the pins 221 and the bushings 222 are, again, made of steel and sintered bronze, respectively, to ensure the necessary robustness.

[0043] Due to the use of a lighter material and the fact that the amount of material used is significantly less than that of the joint 20 (the outer body of the joint 220 is, indeed, formed only by the plates 223a, 223b and 224a, 224b rather than comprising a whole cylindrical surface), the joint 220 has a remarkably reduced mass.

[0044] A comparison between Figure 4 and Figure 6, which are drawn at essentially the same scale, also shows that there is a diameter and height reduction by approximately 30% with respect to the joint 20. This also contributes to the reduction in overall mass. Measurements taken have shown that said reduction is on the order of 85% and allows a reduction in inertia on the order of 95%.

[0045] Notwithstanding the reduction in diameter and height, the diameter of the pins 221 and bushings 222 has been kept unaltered in order to ensure the necessary robustness of the whole.

[0046] Due to the reduction in the height of the joint 220, it was also possible to lengthen the sliding guide of the element that, in the coupling members 12, applies the axial compensating load. This makes it possible to further reduce the oscillation of these members.

[0047] Finally, the tests carried out also showed a marked improvement in the repeatability of the compensating axial load, with a reduction on the order of 60% in the range of variability.

[0048] The above clearly shows that the invention overcomes the problems of prior art.

[0049] It is apparent that the above description has been given merely by way of example and that numerous variations and modifications are possible without leaving the scope of protection of the invention as defined by the appended claims.

[0050] For example, even if for the sake of clarity the shafts 13 - 16 have been considered as separate elements in the description and drawings, some of them (for example, the shafts 14 and 16 in the embodiment of Figure 3 and the shaft 13 and 15 in the embodiment of Figure 5) can actually be part of one and the same shaft. In addition, the joint 220 could also be made of plastics instead of aluminum.

[0051] Of course, the various mechanical components shown can be replaced by components with the same functionality.

Claims

CLAIMS1. Rototranslating capping head (201) for applying screw caps to containers, including: a driving system (10) driving the movements of the capping head (201) along and about a rotation axis; cap-handling members (11) the rotation and the translation of which are driven by the driving system (10); coupling members (12) transmitting the movements from the driving system (10) to the cap-handling members (11) and comprising clutch means for controlling the torque applied to a cap and elastic means for applying a predetermined axial load to the cap; rototranslating shafts (13, 14, 15, 16) which connect together the driving system (10), the coupling members (12) and the cap-handling members (11) and are kept mutually aligned by guiding and supporting elements (102, 103) forming a hyperstatic structure; and a compensating j oint (220) interposed between a pair of said rototranslating shafts (13, 14, 15, 16) in order to recover angular and planar offset errors of said shafts relative to the axis of a container; characterized in that said compensating j oint (220) is arranged between the coupling members (12) and the cap-handling members (11) and connects an output shaft (16) of the clutch means with a shaft (14) to which the cap-handling members (11) are fastened.

2. Capping head (201) according to claim 1, wherein the elements of the joint (220) intended to be coupled to the shafts (16, 14) are formed by a pair of elongated and parallel horizontal plates (223a, 223b) the longitudinal dimensions of which are respectively oriented along the directions in which radial movements of the joint intended to recover offset errors take place, and by a pair of vertical plates (224a, 224b) acting as supports for means (221, 222) allowing said radial movements.

3. Capping head (201) according to claim 2, wherein the joint (220) is made of aluminum.

4. Capping head (201) according to claim 2, wherein the joint (220) is made of plastics.

5. Capping head (201) according to any of the preceding claims, intended for capping containers located within an aseptic space, wherein the coupling members (12) are arranged outside said aseptic space.

6. Capping machine (100) for applying screw caps to containers, comprising one or more capping heads (201) according to any of the preceding claims.

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