DESCRIPTION

Field of application

The present invention generally applies to the technical field of gearboxes.

In the present application, the term "gearbox" means a device to transmit the rotary motion with a given transmission rate from a driving shaft belonging to a first device to a driven shaft belonging to a second device.

State of the Art

As known, i gearboxes are widely used in the industry to transmit a rotary motion between two devices working at mutually different rotational speeds.

Typically, a gearbox consists of a casing that defines a recess that houses two shafts, bearings to rotatably support the shafts on the casing, and a gear for the transmission of the rotation between the two shafts with a given transmission rate.

The two shafts of the gearbox can be arranged coaxial, or with parallel but staggered axes, or yet having non-parallel non-intersecting axes, typically belonging to two respective, mutually orthogonal planes.

The two shafts are provided with shaped ends suited to coupling with, respectively, corresponding shafts belonging to two external devices. Typically, one of the two devices is a motor, while the other one is a machine tool, or another machine requiring a rotary motion.

The gear can be worm type, bevel-gear type, or any other kind, as long as it is suited to transmit the rotary motion between the two shafts with the given transmission rate. Typically, the gear is configured so that the rotational speeds of the two shafts are mutually different.

Generally, the gearbox also comprises sealing means to prevent liquids from entering from the outside to the inside of the casing, and/or to prevent lubricant inside the casing to leak outside thereby.

Concerning the casing, it can be manufacturing in metal by casting in a mold and later mechanical machining of the thus obtained molded part. A metal that is especially used is aluminum, due to its lightness and machinability.

Nevertheless, aluminum has the drawback of being incompatible for some uses, for example in chemical aggressive environments, or in contact with food.

In the latter cases, it is known to make the gearbox casing in materials that resist to corrosion, or that are food-compatible, such as stainless steel, in particular AISI 304 or AISI 316. According to the known techniques, the casing is made through a process similar to the process for making aluminum casings, i.e. by casting stainless steel in a mold and then by mechanical machining of the molded part.

Nevertheless, due to the limited machinability of stainless steel compared with aluminum, the stainless steel casings have the drawback of being particularly expensive. The above drawback is further emphasized with AISI 316.

A further drawback of stainless steel casings is that they have a weight much higher than the aluminum casings.

Summary of the invention

The present invention is aimed at overcome at least partly the above mentioned drawbacks of the known art.

In particular, is an aim of the invention to make a stainless-steel gearbox device having a substantially lower cost compared to that of a stainless-steel gearbox of known type and with equivalent mechanical performances.

Another aim of the invention is that the above gearbox device has a lower weight compared to the weight of a stainless steel gearbox of known type.

It is also an aim of the invention that the gearbox device is perfectly interchangeable with the gearboxes of known type made in the same material.

It is also an aim of the invention that the gearbox device has a reduced impact on the warehouse costs.

It is further aim of the invention that the gearbox device can be easily assembled, at least partly, at a distance from the production facility.

The above mentioned aims are achieved by a gearbox kit according to claim

1 . The above mentioned aims are also achieved by a gearbox device used the above mentioned kit, according to claim 11.

The above mentioned aims are also achieved by a method for manufacturing a gearbox device, according to claim 14.

Further detail features of the invention are specified in the corresponding dependent claims.

According to a first aspect of the invention, the kit comprises a shell to house a gearbox of known type, the shell being suited to be fastened to the gearbox and being provided with through holes arranged at the level of the gearbox shafts to allow coupling them to the external devices.

According to a further aspect of the invention, the shell is in metal sheet.

According to a further aspect of the invention, the material of the shell is different from the material of the gearbox casing. For example, the material of the casing can be unsuited for the use to which the gearbox device is addressed, while the material of the shell can be suited for the above mentioned use.

Some embodiments of the invention may envisage that the shell is made in stainless steel, for example AISI 304 or AISI 316.

Some embodiments of the invention may envisage fluid-sealing elements, in particular liquid-sealing elements, suited to prevent fluids to enter inside shell from the outside thereby when the gearbox is housed in the shell.

Some embodiments of the invention may envisage that the gearbox be fastened to the shell through through holes provided on the shell, that can be aligned with the already provided holes for connecting the devices to the flanges on the gearbox casing.

Advantageously, the fact of using a gearbox housed in a separate shell allows to limit the costs for the gearbox device, mainly when the device is directed to a use requiring a particularly expensive casing. For example this is the case for gearboxes used in chemical aggressive environments, and/or used in food processing plants, that are required to have stainless steel casings.

in fact, advantageously, the shell of the invention allows to isolate the gearbox from the surrounding environment, allowing to employ a gearbox with a casing in a material unsuited to the use, hence relatively cheap, enclosed in a shell in a material suited to such a use.

Consequently, it is advantageously possible to provide a gearbox device suited for a particular use, yet at a substantially lower cost compared to that of a gearbox of known type having a casing entirely made in a material suited for the above mentioned use.

Still advantageously, the fact of making the shell in metal sheet allows to prevent both the casting process, and the further mechanical machining, further reducing the cost of the gearbox device.

Still advantageously, it is possible to limit the warehouse costs, since it is not necessary to stock gearboxes having casings in different materials, being it enough to stock gearboxes having casings in the same material, together with the shells in the more expensive material.

Still advantageously, the possibility to associate the shell with the gearbox at a time and place subsequent to those of the manufacture of the two components allows a more flexible management of the sales network, because the assembly of the shell to the gearbox may occur directly at the dealers' if and when needed.

I above mentioned aims and advantages, together with other that will be mentioned hereinafter, will appear more evidently from the following description of some preferred embodiments of the invention, that are explained for exemplary and non limiting purpose with the help of the attached drawings.

Brief description of the drawings

Fig. 1 depicts the gearbox device of the invention, in axonometric view.

Fig. 2 depicts the gearbox device of Fig. 1 , in exploded axonometric view.

Figs. 3 and 4 depict, respectively, two components of the kit of the invention for making the gearbox device of Fig. 1 , in axonometric view.

Fig. 5 partly depicts the gearbox device of Fig. 1 , in lateral view.

Fig. 6 depicts the gearbox device of Fig. 1 , in cross-section view according to the section plane VI-VI of Fig. 5. Fig. 7 depicts a detail of Fig. 6 in enlarged view.

Figs. 8 and 9 depict, respectively, the developments on a plane of the two components of Figs. 3 and 4, in plan view.

Fig. 10 depicts a different embodiment of the gearbox device of the invention, in exploded axonometric view.

Fig. 11 depicts the gearbox device of Fig. 10, in cross-sectional view according to the plane XI-XI of Fig. 10.

Fig. 11 A depicts detail B of Fig. 11 , in enlarged view.

Fig. 12 depicts a variant embodiment of the gearbox device of the invention, in exploded axonometric view.

Fig. 13 depicts the gearbox device of Fig. 12, in cross-sectional view according to plane XIII-XIII of Fig. 12.

Fig. 13A depicts detail C of Fig. 13, in enlarged view.

Fig. 14 depicts a further embodiment of the gearbox device of the invention, in axonometric view.

Figs. 15 and 16 depict the gearbox device of Fig. 14, in front and lateral views, respectively.

Fig. 17 depicts the gearbox device of Fig. 14, in cross-sectioned view according to plane XVII-XVII of Fig. 15.

Fig. 18 depicts the gearbox device of Fig. 14, in cross-sectional view according to plane XVIII-XVIII of Fig. 16.

Detailed description of some preferred embodiments

The gearbox kit of the invention will be disclosed making reference to a gearbox device 18, indicated on the whole with 1 in Fig. 1.

As can be observed in Figs. 5 and 6, the gearbox device 18 comprises a gearbox 19 that is provided with a casing 22 defining a recess 23 housing two shafts 20, 21 , rotatably supported to the casing 22 through bearings 24 that are housed in the casing 22 as well. The casing 22 also houses a gearing 25 for the transmission of the rotation between the two shafts 20, 21 with a given transmission rate.

In the embodiment depicted in the figures, the two shafts 20, 21 have non- parallel, non-intersecting axes belonging to two respective mutually orthogonal planes. Nevertheless, in variant embodiments of the invention the shafts may be coaxial, or may have parallel and staggered axes, or may have any other configuration.

The two shafts 20, 21 comprise ends 20a, 21a, 21b accessible from the outside to couple, respectively, with corresponding shafts belonging to two external devices, not depicted in the figure but per se known. Preferably, the coupling of each shaft 20, 21 to the corresponding shafts of the two external devices is obtained through tongues inserted in specifically provided seats made in the shafts 20, 21.

Still preferably, the first shaft 20 is suited to receive a torque from a driving device through the end 20a, while the second shaft 21 is suited to supply a torque to a user machine, for example a machine tool, through an end 21a. Still preferably, the second shaft 21 comprises two ends 21a, 21b on two opposite sides of the gearbox 19, accessible from the outside, allowing to connect the corresponding external device indifferently on either sides of the gearbox.

Concerning the gearing 25, in the embodiment depicted in the figures it is a bevel gear. Nevertheless, in variant embodiments of the invention, the gearing may be essere a worm or any other kind, provided it is suited to transmit the rotary motion between the two shafts with the given transmission ratio.

Preferably, the gearbox 19 also comprises sealing devices 30 to prevent liquids entering the recess 23 of the casing 22 from outside thereby, and/or to prevent lubricant in the recess 23 from leaking outside. Preferably, the above mentioned sealing devices 30 comprise sealing rings in elastomeric material, such as V-Ring, interposed between the casing 22 and each of the two ends 21a, 21b of the second shaft 21. The above mentioned sealing rings are sealingly housed in corresponding seats of the casing 22, near each end 21a, 21b of the second shaft 21 , and each one of them comprises a hole delimited by a lip that houses the second shaft 21 and that is kept in contact with the corresponding end 21a, 21b of the shaft itself.

The gearbox device 18 also comprises a kit 1 , in turn comprising a shell 2 that delimits a housing 2a, that can be seen in Fig. 5, configured to house the above mentioned gearbox 19 in an operating position. It is noted that in Fig. 5 the front part of the shell 2, indicated with numeral 11 in the exploded view of Fig. 2, is omitted so as to allow seeing the inside of the shell.

As can be observed in the above mentioned Fig. 2, the shell 2 comprises a first through hole 3 and a second through hole 4 arranged coaxial, respectively, to the two shafts 20, 21 of the gearbox 19 arranged in operating position. The first through hole 3 and the second through hole 4 allow to connect the shafts of the external devices, respectively, with the end 20a of the first shaft 20 and with a first end 21a of the second shaft 21.

Still preferably, the shell 2 comprises a third through hole 5 coaxial with the second shaft 21, that advantageously allows to connect one of the above mentioned two external devices to the second end 21b rather that to the first end 21a.

The kit 1 also comprises fastening elements 16 to fasten the shell 2 to the gearbox 19.

It can be understood that the above disclosed kit 1 allows to obtain a gearbox device 18 suited for a given specific use by employing a gearbox 19 that is suited for a general use but not for the above mentioned specific use. In fact, the gearbox 19 is enclosed in the shell 2, hence it is sufficient that the material of the shell 2 be suited to the specific use. On the contrary, since the gearbox 19 is protected by shell 2, hence it is not exposed to the external environment, its casing 22 can be made in any material, even one that is unsuited for the above mentioned specific use.

Therefore, when the above mentioned specific use requires the surfaces of the gearbox device 18 that are exposed to the operating environment to be made in a first material, and if the casing 22 of a gearbox 19 made in the first material is more expensive compared to a casing made in a second material suited to a generic use, the invention allows to use a gearbox 19 provided with a casing 22 in the above second material, enclosed in a shell 2 made in the first material, so as to limit the cost of the latter and, consequently, the cost of the gearbox device 18.

For example, if the use of the gearbox device 18 requires the material of the latter that is exposed to the outside to be stainless steel, for example AISI 304 or AISI 316, it is possible to employ a gearbox 19 with an aluminum casing enclosed in a stainless steel shell 2. Such use might be, for example, a use in an environment having given chemical features, or a use in a plant for processing food substances.

Advantageously, the above mentioned gearbox device 18 has a weight substantially lower compared to a gearbox of known type having stainless steel casing, because only a part of it, that is its shell 2, is made in stainless steel, while the casing 22 of the gearbox 19 is in aluminum, that is a substantially lighter metal.

Moreover, the gearbox device 18 has a limited impact on warehouse costs, since it can be made by adding the shell 2 to a gearbox 19 that is suited also for a generic use, that, as seen above, can be particularly cheap, thus avoiding the need of providing a specially-made gearbox of a different kind and more costly.

Moreover, the gearbox device 18 can be assembled in a place remote from the place where the gearbox 19 and the kit 1 are manufactured, by sending these two components to the former place. Still advantageously, if the gearbox 19 is of generic kind, it can be easily found everywhere, hence it is sufficient to send only the kit 1 to the place where the assembly is performed, thus limiting the corresponding delivery costs.

The lower cost of the gearbox device 18 can be achieved, in particular, by making the shell 2 through a technique different and cheaper compared to that used to make the casing 22 of the gearbox 19. For example, the casing 22 is generally made through casting a metallic material, for example aluminum, in a mold and by subsequent mechanical machining of the thus obtained molded piece. The mechanical machining is necessary because it allows to achieve the required dimensional and geometrical tolerances on the surfaces for coupling the bearings. As previously said, aluminum is particularly used because of its lightness and machinability, that allow to limit the cost of the casing 22. On the contrary, the stainless steel, such as AISI 304 and, in particular, AISI 316, are metals that are difficult to machine.

Therefore, preferably, the shell 2 is made in metal sheet, for example in stainless steel, come AISI 304 o AISI 316. In particular, the shell 2 is made starting from the above mentioned metal sheet through cutting and/or forming and/or bending and/or welding processes, and/or any other process to confer the shell 2 the desired shape. Further mechanical processes, for example machining processes, may be performed for finishing purposes, in case a particular dimensional and/or geometric precision is required.

A particularly advantageous shape of the shell 2 is that of a parallelepiped, that advantageously allows to limit the number of folds and welds on the metal sheet, so as to simplify the manufacturing process and limit the manufacturing cost of the shell 2. Still advantageously, the above mentioned parallelepiped shape makes the gearbox device 18 particularly suited to the use in food processing plants, since it ease the removal of residues that can possibly accumulate on the surface of the shell 2 during use.

Preferably, and as can be observed in Fig. 4, the shell 2 comprises a box 9 that at least partly defines the housing 2a. The box 9 is provided with a mouth 10 to insert the gearbox 19 in the housing 2a in the above mentioned operating position.

The shell 2 also comprises a cover 11 , that can be seed in Fig. 3, to close the above mouth 10.

Preferably, the box 9 and the cover 11 are configured so as to be arranged facing, respectively, the two opposite ends 21a e 21b of the second shaft 21. In this case, it can be understood that the first through hole 3 and the second through hole 4 belong to the box 9, while the third through hole 5 belongs to the cover 11.

Preferably and as can be observed in Fig. 6, the mouth 10 has a lower transverse dimension compared to the transverse dimension of the box 9. In particular, and as can be observed in details in Fig. 7, the lateral walls of the box 9 have respective edge portions 10a that perimetrally delimit the mouth 10, and that project towards the inside of the box 9 with respect to the remaining portions of the corresponding lateral walls.

In this way, an edge 11a of the cover 11 can be arranged so that it overlaps the above mentioned edge 10a of the box 9 so as to surround it. Figs. 8 and 9 depict, by way of example, a development of the box 9 and of the cover 11 when made in metal sheet. Each one of the above mentioned developments has a central area having a generally rectangular shape, from which four lateral strips project, the strips having generally rectangular shape as well and being folded according to the dash-dot lines until arranging them orthogonal to the central area. After folding, two opposite edges of each strip is arranged adjacent to, respectively, the edges of two other strips, so as to obtain the shapes that is showed, respectively, in Figs. 4 and 3. As to the box 9, it is further envisaged to fold the edges 10a so that, once the strips of the box 9 have been folded, the edges 10a are arranged towards the inside of the box 9 itself, as previously explained. Subsequently it is possible to weld the mutually adjacent edges of the different strips in both the box 9 and the cover 10.

Preferably, the kit 1 also comprises a first sealing element 12, schematically depicted in Figs. 6 and 7, that allows to achieve a sealed coupling of the cover 11 to the mouth 10. In particular, the first sealing element 12 prevents a liquid, for example a rinsing liquid, from entering inside the housing 2a from the outside thereby, and also prevents a lubricating liquid leaking out from the casing 22 in the housing 2a from escaping to the outside of the latter. The first sealing element 12 may comprise, for example, a sealing paste, or an elastomeric body, interposed between the mouth 10 and the cover 11.

Still preferably, the gearbox device 18 comprises further sealing elements associated to the holes of the shell 2, that are configured to prevent liquid from entering from, and escaping to, the outside of the housing 2a through the holes themselves. Preferably, the above mentioned further sealing elements comprise the sealing devices 30 previously disclosed, that are arranged interposed between the shafts 20, 21 of the gearbox 19 and the components of the kit 1 , as will be better explained hereinafter. Advantageously, the fact of using the sealing devices 30 of the gearbox 19 also for sealing the gearbox device 18 allows to limit the use, in the latter, of further components in addition to to those already provided for the gearbox 19.

Still preferably, the above mentioned sealing devices 30 comprise a further sealing ring, of a kind substantially similar to those just disclosed, sealingly associated to the first shaft 20.

Advantageously, the first sealing element 12 and the sealing devices 30 allow to completely isolate the gearbox 19 from the external environment.

Therefore, advantageously, the gearbox device 18 is particularly suited to be used in food production plants, in which mechanical components are required to be periodically washed and must not release harmful substances that might contaminate the food.

Concerning the fastening elements 16, they preferably comprise a first plurality 6 of fourth through holes 17 arranged around the first through hole 3, a second plurality 7 of fourth through holes 17 arranged around the second through hole 4, and a third plurality 8 of fourth through holes 17 arranged around the third through hole 5.

The fastening elements 16 also comprise screw elements 31 provided with respective threaded ends, that are inserted in the fourth through holes 17 and whose threaded ends project in the housing 2a and are screwed to corresponding threaded holes 26 belonging to the casing 22, that can be seen in Fig. 6.

Preferably, the above mentioned threaded holes 26 are the same holes that are already provided to fasten to the casing 22 respective flanges 13, 14, 15 to connect the external devices. In such a way, advantageously, the fastening of the shell 2 to the gearbox 19 is made with no need to provide any additional hole in the casing 22. Still advantageously, the above mentioned threaded holes 26 may be used to fasten the external devices to the casing 22, keeping a complete interchangeability of the gearbox device 18 with the gearbox 19.

Preferably, and as can be observed in particular in Fig. 6, the first through hole 3 and the corresponding first plurality 6 of fourth through holes 17 are made passing through a first reference surface 27 belonging to the shell 2 and facing towards the inside of the housing 2a and in contact with the gearbox 19 arranged in operating position. Preferably, the above mentioned first reference surface 27 is flat.

Still preferably, the shell 2 comprises a second reference surface 28 and a third reference surface 29, facing towards the inside of the housing 2a, whose relations, with respect to, respectively, the second through hole 4 and the third through hole 5, are similar to the relation between the first reference surface 27 and the first through hole 3. With respect to the above mentioned second reference surface 28 and third reference surface 29, similar considerations as previously made for the first reference surface 27 apply.

If needed the shell 2 may have portions 32 projecting towards the outside, corresponding to as many projections in the housing 2a to receive corresponding projecting parts of the gearbox 19, as can be observed in Fig. 6.

Preferably, the kit 1 also comprises a first flange 13 provided with a first through hole 13a and with one or more second through holes 13b. The first flange 13 can be arranged in a corresponding reference position in which it is outside of, and in contact with, the shell 2 so that the first through hole 13a of the first flange 13 is arranged coaxial to the first through hole 3 of the shell 2, and so that the second through holes 13b of the first flange 13 are aligned, respectively, to the fourth through holes 17 of the first plurality 6. In this way, the fastening of the first flange 13 to the gearbox device 18 is made at the same time as the fastening of the shell 2 to the gearbox 19, and using the same screw elements 31 and threaded holes 26, to advantage of the ease of use and of the reduction of the number of components.

Still preferably, the first flange 13 is further provided with third through holes 13c for fastening an external device, for example a driving device.

Still preferably, the kit 1 comprises a second flange 14 similar to the first flange 13 and provided with a first through hole 14a that can be arranged coaxial with the second through hole 4 of the shell 2. The second flange 14 is provided with one or more second through holes 14b that are aligned, respectively, to the fourth through holes 17 of the second plurality 7.

Still preferably, the kit 1 comprises a third flange 15 similar to the first flange 13 and provided with a first through hole 15a that can be arranged coaxial to the third through hole 5 of the shell 2. The second flange 15 is provided with one or more second through holes 15b that are aligned, respectively, to the fourth through holes 17 of the third plurality 8. Similar considerations as previously made for the first flange 13 also apply to the second flange 14 and to the third flange 15, including the way the corresponding reference positions are defined.

Preferably, and as can be observed in Fig. 6, the three flanges 13, 14 and 15 cooperate with the sealing devices 30 previously disclosed to ensure the fluid tightness of the shell 2. In particular, a sealing device 30 is arranged in contact with the first through hole 13a of the first flange 13, while other sealing devices 30 are interposed between the casing 22 and the surfaces facing the shell 2 and belonging, respectively, to the second flange 14 and to the third flange 15.

Figs. 10 and 11 depict a second embodiment of the invention in which the gearbox device, the gearbox and the kit are indicated by numerals 45, 46 and 40, respectively. For the sake of simplicity, the remaining components in this embodiment are indicated with the same numerals as the corresponding components of the previously disclosed embodiment that have the same functions.

This second embodiment differs from the previous one substantially because the kit 40 comprises a reinforcement element 41 that can be associated to the mouth 10 of the box 9 to prevent or limit the deformation of the mouth 10 consequent to, e.g., an external crushing action.

The above mentioned reinforcement element 41 is provided with a central portion 42 perimetrally delimited by two edge portions 43 that project from respective mutually opposite sides of the central portion 42 in a direction incident on a surface thereby, so as to be mutually facing. In particular, the reinforcement element 41 is configured to be associated to the box 9 so as to be arranged in an operating position that is depicted in more details in Fig. 11. In the above mentioned operating position, the edge portions 43 are arranged in the box 9 so as to face, respectively, two corresponding mutually facing and mutually opposite portions 10b belonging to the edge 10a of the mouth 10. In this way, advantageously, the reinforcement element 41 is capable to withstand a crushing action on the edge 10a directed according to a direction that is defined by the alignment of the two edge portions 43.

Preferably, the two edge portions 43 are configured so as to be in contact with the two portions 10b of the edge 10a and, still preferably, to be interference-fitted to them when the reinforcement element 41 is in the operating position in order to, advantageously, stiffen the mouth 10 so as to increase its overall strength, e.g., to possible shocks.

Preferably, the reinforcement element 41 comprises two further edge portions 43 similar to those just disclosed, except for projecting from two further mutually opposite sides of the central portion 42. The above mentioned two further edge portions 43 are configured in such a way as to make the reinforcement element 41 capable to withstand a crushing action on the edge 10a directed according to a direction incident on, and preferably orthogonal to, that corresponding to the other two edge portions 43.

Preferably, the two edge portions 43 belonging to each one of the above mentioned two pairs are arranged mutually parallel, so that the four edge portions 43 on their whole define a parallelepiped.

Preferably, the reinforcement element 41 also comprises a stop portion 44 configured to be arranged in contact with the edge 10a of the mouth 10 during insertion of the edge portions 43 in the box 9, so as to limit the above insertion. Advantageously, the stop portion 44 allows to precisely define the operating position for the reinforcement element 41.

Preferably, the stop portion 44 comprises one or, more preferably, two, corresponding flap pairs 44a, the two flaps 44a of each pair being adjacent to two corresponding mutually opposite edge portions 43 and projecting with respect to these according to respective mutually opposite directions, so as to rest on the edge 10a of the mouth 10 while remaining outside of the mouth 10 itself, as depicted in Fig. 11 A.

Preferably and as can be observed in Fig. 10, the above mentioned flaps 44a are arranged near respective vertices of the reinforcement element 41 , that in this case has generally a shape of a parallelepiped. For the sake of simplicity, in Figs. 10 and 11 , the numeral 44a is used only with reference to one of the four flaps above disclosed. Still preferably, the central portion 42 and the stop portion 44 define a single smooth and, preferably, flat, surface of the reinforcement element 41.

Preferably, the reinforcement element 41 is obtained by a metal sheet. Still more preferably, the central portion 42, the edge portions 43, and the stop portion 44 all belong to the same metal sheet. The reinforcement element 41 may be obtained, for example, by cutting the above mentioned metal sheet and by folding its edges so as to obtain the above edge portions 43.

Preferably, each of the above mentioned folds is made for an angle bigger than 90°, so as to arrange the edge portions 43 to slightly overlap the central portion 42. Advantageously, the configuration just disclosed facilitates the insertion of the edge portions 43 in the box 9.

In all cases above disclosed, the reinforcement element 41 is configured in such a way that, when in operating position, it allows positioning the cover 11 to close the mouth 10 as previously disclosed.

In Figs. 10 and 11 it can be observed that the gearbox 46 above disclosed is of the kind having shafts 20, 21 arranged coaxial, the end 20a of the driving shaft 20 is arranged so as to project with respect to the shell 2, and the driven shaft 21 has only one end 21a accessible from outside. Nevertheless, it is apparent that what above disclosed is also applicable to a different variant embodiment, in which the gearbox has its shafts 20, 21 of a kind similar to those of the first embodiment previously disclosed.

A variant embodiment of the kind just mentioned is depicted in Figs. 12, 13 and 13A, in which the gearbox is indicated by 46', the respective gearbox device by 45', and the kit by 40', while the other components are indicated using the same numerals used for the components having similar functions in the previous variant embodiment, whose disclosure is hereby used for reference. Particularly, Fig. 13A is similar to Fig. 11A of the previous variant embodiment, and allows to see the coupling between the edge portions 43 of the reinforcement element 41 and the portions 10b of the edge of the mouth 10. In the same figure it can further be seen that flaps 44a become arranged in contact with the edge 10a of the mouth 10. Figs from 14 to 18 depict a third embodiment of the gearbox device of the invention, thereby indicated by numeral 52. For this embodiment as well, the components having functions similar to the components in the above disclosed embodiments are referred to using the same numerals, if not otherwise specified.

The gearbox device 52 comprises a gearbox 53, whose cross-section can be seen e.g. in Fig. 17 and that, by way of mere example, is of the worm kind and has shafts 20, 21 arranged according to mutually orthogonal axes. Still by way of example, gearbox 53 is configured according to the US technical standards and, in particular, it has a casing 22 substantially parallelepiped- or prismatic-shaped.

The kit 50 of the above mentioned third embodiment has a second flange 14 provided with a support portion 51 that can be inserted in the second through hole 3 of the shell 2 when the second flange 14 is arranged in the corresponding reference position, as can be observed in the cross-sectional view of Fig. 18. The support portion 51 defines a corresponding inner cylindrical seat 51a that, in the above mentioned reference position, is arranged inside the shell 2 to house the bearing 24 that supports an end of the second shaft 21. In particular, the outer surface of bearing 24 is coupled with the above mentioned inner cylindrical seat 51a with the interference that is required for the usual couplings between seats and bearings.

Advantageously, the second flange 14 in the configuration just described carries out the dual function of fastening the shell 2 to the casing 22 of the gearbox 19, and of supporting the bearing 24, thus allowing to limit the constructive complexity for the gearbox device, as well as its overall dimensions.

Preferably, the kit 50 also comprises a third flange 15, arranged opposite to the second flange 14 and having a thereby similar configuration. Inner cylindrical seats 51a of the two flanges 14 and 15 are coupled to, respectively, two bearings 24 that, preferably, support shaft 21 at the opposite ends thereby.

Concerning the supporting of the driving shaft 20, the corresponding bearings 24 may be coupled to corresponding seats made in the casing 22 of the gearbox 53, as can be seen in Fig. 17. Nevertheless, in variant embodiments of the invention, not depicted in the drawings, the first flange 13 may have a configuration similar to that above disclosed for the second flange 14 and for the third flange 15, in order to carry out the function to support a corresponding bearing.

In the above mentioned third embodiment, preferably the shell 2 is configured so that the through holes that house the shafts 20, 21 are all made in the box 9 rather than in the cover 11. This concerns in particular the first through hole 3 that houses the driving shaft 20, as well as the second through hole 4 and the third through hole 5 that house the corresponding mutually opposite ends of the driven shaft 21 .

Preferably, the cover 11 is fastened to the casing 22 of the gearbox 53 through screws 54, as can be observed e.g. in Fig. 14.

Still preferably, similar screws 54 are used to fasten the lower wall of the box 9 to the casing 22, in addition to the flanges 13, 14 and 15 and to the corresponding screw elements 31, as can be observed in Figs. 15-17.

As previously anticipated, the invention also concerns a method for manufacturing the gearbox device 18, 45, 52 according to any one of the embodiments above disclosed.

Making reference to the first embodiment, the above mentioned method envisages to provide a gearbox 19 of the kind that has been previously disclosed, and a shell 2 provided with a first through hole 3 and a second through hole 4, the shell 2 delimiting a housing 2a to accommodate the gearbox 19 in an operating position. The operating position just mentioned is such that the first through hole 3 and the second through hole 4 are coaxial, respectively, to the two shafts 20, 21 of the gearbox 19.

Preferably, the shell 2 is made from a metal sheet, as previously explained.

The gearbox 19 is then arranged in the housing 2a in the above mentioned operating position and the shell 2 is fastened to the casing 22.

Preferably, the fastening of the shell 2 to the casing 22 is made using one or more fourth through holes 17 belonging to the shell 2 and that can be aligned to corresponding holes 26 belonging to the casing 22 when the gearbox 19 is arranged in operating position. In each one of the above mentioned fourth through holes 17 a corresponding fastening element 8, for example a screw element 31, is inserted, an end of which is fastened, e.g. screwed, to a corresponding one of the above mentioned holes 26 of the casing 22.

Preferably, the shell 2 is in a second material different from the material of the casing 22. Still preferably, the material of the casing 22 is of a kind unsuited for food use, while the material of the shell 2 is of a kind suited to food use.

Advantageously, the above mentioned method can be applied to adapt a gearbox 19 to a use to which the gearbox is unsuited, without requiring any change to the external devices. In particular, the method allows adapting a gearbox 19 having an aluminum casing to be used in a chemically aggressive environment or in a food processing plant, through using a stainless steel shell 2 in the way above explained.

Apparently, the considerations already presented during the previous description of the gearbox device 18 apply, with the duly and obvious adaptations, to the above mentioned method. In particular, the method may comprise any operation that is suited to make the different components of the gearbox device 18 and that implicitly results from the previous description.

It is also apparent that the above method is applicable as well, in a similar way, to the other above disclosed embodiments of the gearbox device.

From the above, it is understood that the kit, the gearbox device and the method of the invention achieve the intended aims.

In particular, the use of a gearbox having aluminum casing or similar material, covered with a stainless steel shell, allows to make a gearbox device that is equivalent to a gearbox with stainless steel casing, yet having a cost and a weight substantially lower than those of the latter gearbox.

Moreover, using the gearbox holes that are provided for coupling the gearbox to the external devices, to fastening the shell to the gearbox, allows the perfect interchangeability of the so obtained gearbox device with a gearbox of known type, made in the same material of the shell.

Moreover, since the same gearbox can be employed to make all of a series of gearbox devices suited to different uses by providing shells with different materials, it is possible to limit the overall number of components needed to obtain the series, hence limiting the corresponding warehouse costs at the manufacturer's side.

Moreover, the use of screw elements to fasten the kit to the gearbox allows to assemble the gearbox device also remotely from the facility where the components are manufactured.

The invention is susceptible of changes and variant embodiments, all falling within the inventive concept expressed in the attached claims. In particular, the elements of the invention may be replaced by other elements technically equivalent thereby.

Moreover, the materials may be chosen according to the needs, yet without departing from the scope of the invention.

Moreover, one or more elements of a specific embodiment of the invention that are technically compatible with another specific embodiment of the invention, may be used in the latter one in addition to, or in replacement of, elements of the latter one.

When technical elements specified in the claims are followed by reference signs, those reference signs are included for the sole purpose of improving intelligibility of the invention, hence they do not imply any limitation of the claimed scope of protection.