Imported: 10 Mar '17 | Published: 27 Nov '08
USPTO - Utility Patents
A wrapping machine (1) comprises a rotating table (2) for supporting products (14); an upright (3) with a perimeter wall (4) in which there is a longitudinal opening (5); a dispenser unit (6) for a wrapping film (15); and a supporting and connecting structure (7) for the dispenser unit (6), connecting it to the upright (3), comprising a carriage (8) and a plate (9). The carriage (8) can be translatably guided by the upright (3). The plate (9), lying in a vertical plane (10), passes through the upright (3) perimeter wall (4) at the opening (5), and connects the carriage (8) to the dispenser unit (6), so that they can translate together along the upright (3). The structure (7) comprises a vertical bar (11) contained in the upright (3) and translating supporting means (29) which connect the plate (9) to the bar (11) and comprise at least one sleeve (13) coaxially coupled with the bar (11) and at, least able to translate guided on the bar (11).
The present invention relates to the technical sector relative to packaging products and in particular relates to an improved wrapping machine with rotating table.
Industrial product packaging technology already has wrapping machines designed to package products by wrapping them with a continuous film of plastic material.
Such machines basically comprise: a horizontal platform, able to rotate about a vertical axis of rotation, designed to receive the products to be packaged; an upright, adjacent to the platform; and a packaging film dispenser unit, which supports a reel of film and is constrained to the upright, cantilever style, and guided by it so that it can translate longitudinally relative to the upright.
When an initial edge of the film has been made to adhere to the product supported by the platform, the subsequent rotation of the platform causes the film to gradually unwind from the reel and at the same time wrap around the product, enclosing it. Simultaneously, the film dispenser unit is moved along the upright with a translation coordinated with the platform rotation. The combination of the two movements: platform rotation and dispenser unit translation, therefore generates spiral wrapping, gradually extending from the part of the product closest to the platform to the top of the product which is positioned on the platform.
Between the upright and the film dispenser unit the prior art machines of the above-mentioned type have a mechanical interconnection structure which basically comprises a carriage an a plate rendered closely integral with one another. The carriage is contained in the upright and is guided by the latter so that it translates longitudinally relative to the upright.
The connecting plate connects to the carriage in the upright, with the plane in which it lies oriented vertically and, passing through an upright perimeter wall, projects from the upright and is constrained to the dispenser unit, outside the upright. The plate passes through the wall at a guide substantially extending along the entire height of the upright.
A drive unit, at least partly in the upright, allows the translation of the following together: the carriage, the plate and the dispenser unit, with the movement suitably co-ordinated with the platform rotation.
In wrapping machines of the type described above, according to a first prior art technique for construction of the carriage it has a substantially prismatic cage-shaped structure. The cage is shaped in such a way that it has a highly non-deformable overall three-dimensional structure, substantially able to interact with the entire inner profile of the upright. The interaction of the cage with the upright walls, which allows the cage to remain rigidly connected to the upright although free to translate vertically along it, is made possible by a set of idle rollers which are inserted between the cage and the upright and keep the cage centred and guided in the upright.
This construction technique has several considerable disadvantages. Carriage construction is complex. It is relatively heavy and requires the preparation of guide tracks with manoeuvre surfaces suitable for roller rolling, that is to say large surfaces which are expensive to produce. Moreover, due to its physical and functional structure, the cage requires a large manoeuvre space, covering practically the entire inner volume of the upright.
These disadvantages are at least partly overcome by a second prior art technique in which the carriages are in practice made from the same connecting plate which is shaped for the purpose so that it can support the rolling rollers itself. The plate rollers are engaged in two rolling guides, with limited dimensions, which are on both sides of the plate and are associated with the same lateral wall of the upright, proximal to the dispenser unit.
However, such a solution, undoubtedly an improvement in terms of reduced masses, simplified construction and reduced costs, has other disadvantages which although different, are no less important than the previous ones. The flat structure of the carriage in itself means that its overall rigidity is decidedly lower than the rigidity of the three-dimensional cage previously described. As a result, the greater deformability of the carriage with a flat structure, inevitably also transmitted to the film dispenser apparatus, also has a negative effect on the quality and regularity of dispenser apparatus performance. The greater deformability of the plate also has a negative effect on the regularity of roller rolling in the guides. In the absence of a highly non-deformable structure, and in the presence of rolling guides which are very close together, the rollers tend more easily to be skew to the right angle to the direction of forward movement. These skewing actions therefore cause a carriage translation which may be affected by a certain degree of twisting resulting in a corresponding increase in the resistance encountered by the carriage during the translation along the upright, and which consequently mean that more power is required of the actuators which control the driving of dispenser unit translation.
The aim of the present invention is therefore to provide, in accordance with the invention, an improved wrapping machine designed to combine the advantages of the known solutions without any of the relative disadvantages.
The technical features of the present invention, in accordance with the above-mentioned aim, are clear from the claims herein, in particular claim 1 and any of the claims directly or indirectly dependent on claim 1.
FIGS. 1, 2 and 3 illustrate a wrapping machine for packaging products 14 by continuously wrapping with a packaging film 15, preferably made of a plastic material.
The machine 1, as a whole, basically consists of three main parts, respectively a horizontal table 2; an upright 3 and a dispenser unit 6 for the packaging film 15.
The table 2 consists of a low circular platform, designed to receive on its top surface the products 14 to be packaged, the table being able to rotate about a vertical axis of rotation 21, driven by actuator means housed in the table 2 and not illustrated in the drawings.
The upright 3 substantially has the structure of a parallelepiped, with a quadrangular base, hollow inside. The lateral surface of the upright 3 structure comprises a perimeter wall 4, in which there is an opening 5, substantially a narrow slot, longitudinal relative to the upright 3 and straight, along almost the entire height of the upright.
The film 15 dispenser unit 6 has a structure 22 consisting of a pair of flat, parallel ends 23, connected to one another by rods 24 inserted between them and transversal to the ends 23. Inside the structure 22 a reel 25 is housed and supported in which the packaging film 15 is wound over itself.
The film 15 dispenser unit 6 is connected to the upright 3 by a supporting and connecting structure 7 basically comprising a motor-driven carriage 8 and at least one tubular vertical bar 11, contained in the upright 3, with which the carriage 8 is coupled so that it can translate vertically along the upright 3. The carriage 8 is driven by relative drive means 33 comprising a chain 34 forming a loop around a pair of pulleys 35 and 36 of which one 36 is driven by a relative gearmotor 37.
The carriage 8 comprises a frame 26 basically consisting of a flat plate 9 and translating supporting means 29 which can be associated with the plate 9. The plate 9 is oriented in such a way that the plane in which it lies 10 is vertical. The plate 9 is supported by the upright 3 in such a way that it passes through the lateral wall 4 at the opening 5, remaining inserted between the edges 31 of the opening. Thus the plate 9 projects from the upright 3, part of the plate 28 projecting cantilever style. This part 28 of the plate 9 can be connected as a single body with the structure 22 of the film 15 dispenser unit 6, the unit 6 in this way being integral as a single body with the carriage 8 frame 26.
The carriage 8 frame 26 supporting means 29 comprise two sleeves 13, integral with the plate 9. The two sleeves 13 are coaxially coupled with the bar 11, enclosing and gripping it, and constrain the carriage 8 to it, although the carriage remains free to translate longitudinally relative to the bar 11.
The sleeves 13 and the bar 11 have coupling surfaces 16 and 17 geometrically complementing one another, which may usually have any shape. When said surfaces 16 and 17 entail the bar 11 having a polygonal or elliptical profile, the only freedom the carriage 8 has is translating longitudinally relative to the bar 11. If, vice versa, the surfaces 16 and 17 are cylindrical, as illustrated in FIG. 4 of the example described, the carriage 8 is also free to rotate about the bar 11. However, since the carriage 8 plate 9 is constrained to pass through the opening 5 in the wall 4, the operating interaction of the bar 11 and the opening 5 on the frame 26 results in the carriage 8 again only having the freedom to translate longitudinally relative to the bar 11. Although the embodiments described above are all equivalent to one another in operating terms, the latter solution is considered preferable to the others due to its more simple and economical implementation.
Nonetheless it should be noticed, above all in view of what will be said later regarding the rigidity of the carriage 8, that the opening 5 may contribute to carriage 8 guided translation in different ways depending on the cases: being part of the carriage 8 system of constraints as a excess constraint, if the shape of the bar 11 is such that it in itself prevents plate 9 rotation about the bar 11, or as a constraint needed to prevent carriage 8 rotation about the bar 11 if the bar is cylindrical, as in the example in FIG. 4.
Returning to the physical structure of the carriage 8 frame 26, FIG. 4 also shows how the sleeves 13 have an axis 30 for centring on the bar 11 which is outside the plane 10 in which the plate 9 lies. This means that the carriage 8 has a structure with an angular shape, in itself having a high level of intrinsic rigidity, that is to say a high level of non-deformability when subject to external loads. Such a property, if necessary combined with the various types of constraints which can be clearly defined for the carriage 8 from its different interactions with the bar 11 and with the edges 31 of the opening 5, allows a very strong dispenser unit 6 supporting and connecting structure 7. This is particularly significant because, with relatively simple construction, it allows the dispenser unit 6 to operate in a regular, reliable fashion even when it is quite heavy, for example due to the presence of large reels 25 and/or the presence of any accessory units concerning its structure 22, for example film 15 automatic pre-stretching and/or cutting units, or when it is such that it causes quite high intensity film 15 traction.
Returning to the carriage 8 translating supporting means 29, it should be noticed that they may in principle allow carriage 8 translation, operating by sliding or even better by fluidic support. However, for simple construction and low costs the connection between the sleeves 23 and the bar 11 and the plate 9 and the opening 5 in the upright 3 lateral wall 4 is preferably made by inserting rolling bodies 18 between the respective surfaces 16, 17 and 31 joined.
Said rolling bodies 18 consisting of bearings which rotate freelyillustrated in FIG. 4are supported by the plate 9 at parts 32 of the plate directly opposite the edges 31 of the opening 5 in the upright 3 lateral wall 4. There may also be similar spherical rolling bodies 18 for the sleeves 13 when they are made in such a way that they have looped races inside, along which the rolling bodies 18 recirculate continuously to implement the known recirculating ball technique.
In principle, the rolling bodies 18, at least the part of them directly housed in the plate 9, could be straight rollers. However, it should be noticed that the use of spherical rolling bodies 18 in the case in question involves a decidedly reduced carriage 8 resistance to forward movement and, above all, means less expensive production of the openings 5 in the upright 3 lateral wall 4. If spherical rolling bodies 18 are used, accidentally skewing forces applied on the carriage 8, causing it to twist during its translation, would obviously be intrinsically irrelevant.
Nonetheless, it must be emphasised that even in the case of roller-shaped rolling bodies 18, such effects are minimal, since the angular shape of the carriage 8 frame 26, due to the decision not to position the axis 30 for sleeve 13 centring coplanar with the plane 10 in which the carriage 8 plate 9 lies, renders the carriage 8 itself quite rigid and, as such, rather indifferent to the possibility of a translation which is not regular to which a considerable resistance to forward movement must be attributed. As a result, the particular angular shape of the machine 1 carriage 8 disclosed advantageously also allows roller-shaped rolling bodies 18 to be mounted.
The carriage 8 disclosed also has very compact geometric dimensions. Consequently, the carriage 8 manoeuvre volume in the upright 3 is equally contained and practically confined to a space close to the vertex of one of the inner corners 32a of the upright 3.
As a result, apart from the pulleys 35 and 36 and the chain 34 contained in the upright 3, the upright inner volume is practically free of obstacles. In other words, inside the upright 3 there may be a large compartment 19, at the side of the bar 11, which can be used in the machine 1 for the most diverse purposes.
Said compartment 19 may therefore house means 20 for actuating and controlling machine 1 functions, for example a machine 1 control panel. The positioning of such means 20 in the compartment 19 means that they do not need to be housed in a structure physically separate from the upright 3. This results in obvious construction economic advantages and use of less space in the industrial environments in which the machine 1 will be installed.
When the actuating and control means 20 are actuated by integrated electronic boards 38, the compartment 19 may easily house said boards 38. So, in the machine 1 disclosed the integration of all electronic components on a board 38 is quite easy. The above-mentioned boards 38 may also include inverters 39 used to regulate the speed of the motors of the actuators for machine 1 operation, and more specifically inverters 39 for the carriage 8 translation motors. The great ease and regularity of carriage 8 translationresulting, as indicated, from its rigidity, strength, reduced masses, etc.allows the use in the machine 1 of motors with a low power rating. This, in addition to the advantage of lower set up and running costs, equally advantageously makes it possible to use low power inverters 39 which, as such, are easy to include on the board 38 without limitations in terms of a decline in the operating performance and/or reliability of the machine 1, which, due to its sector, is intrinsically subject to intense, heavy-duty use.
Obviously, inclusion in the machine 1 functions actuating and control means 20 of inverters 39 integrated on the board 38 does not necessarily have to be limited to controlling and regulating the carriage 8 speed of translation, but may also advantageously apply to other relevant regulation, for example: the rotating table 2 and/or regulation of the speed of the motors of any pre-stretching units, and/or of film 15 cutting apparatuses, if these are fitted on the film 15 dispenser unit 6.
The invention described has an evident industrial application and may be modified and adapted in several ways without thereby departing from the scope of the inventive concept. Moreover, all details of the invention may be substituted by technically equivalent elements.
One of the possible alternative embodiments of the machine 1 is illustrated in FIGS. 5 to 8. In said Figures substantially identical elements correspond to reference characters which are the same as those previously used. Therefore, the detailed description of them is not repeated, the description being developed only with reference to significant variations.
That being said, FIGS. 5 to 8 show how the bar 11 has a rack 40 and the sleeve 13 in turn has a pinion 41 which engages with the rack 40. The pinion 41 is driven by actuator means 42 associated with the sleeve 13, in particular comprising a gearmotor 43 supported by the sleeve 13.
More specifically, the bar 11 has a mixed line profile 44substantially quadrilateraland has at least one pair of flat opposite faces 45, against which freely rolling bodies 46 on the sleeve 13 make contact and rototranslate.
The sleeve 13 is preferably structured in such a way that it has a pair of opposite plates 47 supporting the rolling bodies 46 inserted between them.
FIGS. 5 and 7 show how the bar 11, the sleeve 13 and the actuator means 42 form an assembly 48 which as a single unit can be associated with or removed from the upright 3. End plates 49 on the bar 11 allow the assembly 48 to be connected to the machine 1 upright 3.
Compared with the solution previously discussed, this alternative embodiment of the invention therefore boasts more simple construction, is easier to assemble and disassemble and, finally, is simpler and less expensive to make. Not forgetting another advantage which is more economical transport, since it is obvious that the machine can be transported disassembled, then reassembled directly at the destination.