PACKAGING MACHINE IN WHICH A PRODUCT IS PACKAGED BY WRAPPING WITH A FILM OF PACKAGING MATERIAL

Abstract

A machine for packaging a product (2) in a wrapper forms the wrapper by wrapping with a film (8) of packaging material, supplied in the form of a continuous web from an apparatus (4) for supplying film (8) which can move relative to the product (2) in such a way that it revolves around the product (2) and translates longitudinally relative to the product (2). The machine (1) comprises mechanical means (10, 5, 14) for synchronising the speed at which the film (8) is supplied with the speed at which the apparatus (4) revolves around the product.

Description

TECHNICAL FIELD

The present invention relates to the technical sector of automatic packaging of products and in particular it relates to a wrapping machine in which products are packaged by forming a wrapper consisting of a film of suitable material which, in the form of a continuous web is wrapped around the product in repeated coils until the product is covered.

BACKGROUND ART

In the above-mentioned technical sector there are prior art packaging machines in which the wrapper is obtained using an unwinding apparatus which supplies a continuous web of film and which is supported by an apparatus that can move on the fixed structure of the machine, its motion consisting of revolution around the product to be packaged and translation longitudinally relative to the product, movements which are suitably synchronised with each other.

More specifically, the speed at which the film is supplied is synchronised with the apparatus revolving speed around the product by synchronising means which use suitable software and electronically control speed synchronisation.

Such synchronising means operate with satisfactory efficiency in the machine operating steps in which the speeds involved are steady, or in any case quite close to said state.

However, during the acceleration and deceleration steps, control is not precise enough, meaning that the above-mentioned synchronising means must be supplemented with a mechanical device, for example of the “dandy roller” type—in which a bar, interacting with the film, depending on the moments increases or reduces the quantity of web supplied—constituting a buffer compensating for any instantaneous synchronisation defect found between the web supply speed and the revolving speed of the movable apparatus.

Such a type of control, although operating in a relatively satisfactory way, may not be completely reliable in all operating situations which may occur in practice. Moreover, from a construction and economical viewpoint, said control may also be complex and expensive.

DISCLOSURE OF THE INVENTION

The present invention has for an aim to overcome the above-mentioned disadvantages with a packaging machine in which the speed at which the film is supplied and the revolving speed of the apparatus supporting the relative unwinding apparatus are mechanically synchronised in such a way as to provide definite, reliable synchronisation in all possible machine operating situations.

The technical features of the present invention, in accordance with the above aims, are clear from the content of the claims herein, in particular claim 1, and from any of the claims directly or indirectly dependent on claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of the present invention are more apparent in the detailed description which follows, with reference to the accompanying drawings which illustrate preferred, non-limiting embodiments of the invention, in which:

FIG. 1 is a perspective assembly view of a machine made in accordance with the present invention;

FIG. 2 is an enlarged view of a part of the machine with some parts cut away to better illustrate others;

FIG. 3 is an enlarged view of a detail from FIG. 2;

FIG. 4 is a view of the detail from FIG. 3 seen from above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

In FIG. 1 of the accompanying drawings, the numeral 1 denotes as a whole a machine 1 for packaging products 2 which substantially has: a parallelepiped structure 20 with a portal delimited by four uprights 21 located at the vertices; a horizontal platform 22 inside the uprights 21; and an annular thrust bearing 23 below the platform 22, which supports an operating apparatus 4 that supplies a film 8 of packaging material.

The horizontal platform 22 is connected in a guide on the uprights 21 substantially at four of its vertices. The platform 22 can move in such a way that it can translate vertically and alternately along the machine 1 structure 20, driven by drive means 37 which are completely conventional and are not strictly part of the present invention, therefore they are not described in detail. During its translating movement, the platform 22 encloses a generic product 2 to be packaged, said product being contained in the space inside the machine, coaxial with the structure 20 and on a stand 19 or an equivalent supporting roller conveyor.

In particular FIG. 2 shows that the operating apparatus 4 comprises a unit 3 for unwinding the film 8 of packaging material, the unit 3 having a reel 30 of packaging material from which the film 8 is unwound in a conventional way in the form of a continuous web, which is then wrapped around the product 2 to be packaged, in this way creating a protective containment wrapper around the product.

FIG. 2 also shows how the annular thrust bearing 23 and the operating apparatus 4 as a whole are integral with each other. The thrust bearing 23 is also coaxial with the platform 22 and can rotate around a platform axis 22a in such a way that it can rotate around said axis 22a at the same time causing the operating apparatus 4 which is integral with it to rotate around the axis 22a. As a result the operating apparatus has a circular revolution trajectory around the product 2.

Rotation of the annular thrust bearing 23 and of the operating apparatus 4 relative to the platform 22 which supports both is motor-driven and is guaranteed by drive means labelled 24 as a whole. Said drive means 24 substantially comprise: a gearmotor 24m equipped with a driving pulley 25; a driving belt 26 with respective belt 26 tensioning pulleys 26t. The driving belt 26 is looped and fits around the thrust bearing 23 and the pulley 25 together and tightly with the contribution of the tensioning pulleys 26t.

The platform 22 also supports a fixed annular race 9 which, being integral with the platform 22, can only translate longitudinally relative to the axis 22a of the structure 20 together with the platform 22 itself.

The supplying apparatus 4 in turn also comprises a speed variator 5 having a motion input shaft 6 connected to a friction wheel 10 which is peripherally connected to the annular race 9 and an output shaft 7 which is connected by a belt drive 14 to a unit 3 for unwinding the film 8 from the reel 30 of the supplying apparatus 4.

Since the apparatus 4 can rotate together with the annular thrust bearing 23 relative to the platform 22 and to the fixed race 9 connected to it, when the thrust bearing 23 is made to rotate around the axis 22a of the structure 20, the wheel 10 rolls on the fixed race 9, causing the input shaft 6 and the output shaft 7 of the variator 5 to rotate, thus driving the belt drive 14 and finally the unwinding unit 3. The reel 30 is therefore made to unwind the film 8 with an instantaneous supply speed which is mechanically correlated with the actual instantaneous speed of rotation of the thrust bearing 23 relative to the platform 22.

It is therefore evident that the wheel 10, the variator 5 and the drive 14 together form a preferred embodiment of more general means for mechanical synchronisation between the revolving speed of the supplying apparatus 4 and the supply or unwinding speed of the film 8. Moreover, the same synchronising means allow the supply motion energy to be derived from a single motor, represented by the gearmotor 24m which drives the apparatus 4 revolving movement around the product 2 to be packaged. This is particularly advantageous both in terms of reliable operation, and in terms of economical construction, because compared with the prior art there is no longer any need for the motor which drives the supplying of film 8 nor the means for management and control of the correlation of operation between the independent drive units of the thrust bearing 23 and of the unwinding apparatus 3.

The race 9, the wheel 10, the variator 5 and the drive 14 may also have detecting means for mechanically detecting the actual revolving speed of the apparatus 4 around the product 2.

In practice, machine 1 operation is obvious at this point from observing FIGS. 1 and 2. By making the vertical translation of the platform 22 motor-driven, synchronised with rotation of the thrust bearing 23 (and with simultaneous synchronised supplying of the film 8), a generic product 2 to be packaged, which is located inside the structure 20, in a central position relative to the platform 22 may be packaged by wrapping it with a web of packaging material placed in such a way that it continuously covers the product 2 as the movable apparatus 4 gradually revolves around the product 2 and as the platform 22 gradually translates longitudinally relative to the product 2.

FIG. 2 and in more detail in FIG. 3 show that the rolling connection is guaranteed by friction between the outside of the wheel 10 and the surface of the race 9. Therefore, the outside of the wheel 10 may advantageously have a covering shell 27 made of a suitable friction material.

Moreover, to guarantee a correct rolling connection even in the presence of any race 9 out-of-roundness, for example due to machine 1 metal structural work construction faults, the operating apparatus 4 may advantageously have a support 12 for the variator 5 which comprises a monolithic plate 33 having two half-surfaces 28 and 29 converging with one another at an angle. A first half-surface 28 connects to itself the variator 5 casing 30. A second half-surface 29 uses two supports 38 to support the variator 5 motion input shaft 6 which, more specifically is indirectly connected to a variator 5 intermediate shaft 31 by a belt drive 32. The plate 33 is connected to the annular thrust bearing 23 by a cylindrical pin 13 with a vertical axis. The pin is on the opposite side of the variator 5 to the wheel 10, and it is offset relative to an ideal joining line passing through the annular thrust bearing 23 axis of rotation 22a and through the variator 5 centre of mass. The plate 33 connected in this way, when subjected to the action of the centrifugal force generated by rotation of the apparatus 4 around the axis 22a, discharges on the wheel 10 a force which presses the wheel 10 against the race 9 and which in that way increases the certainty of having a pure rolling motion of the wheel 10 against the race 9, that is to say, of having a motion which is not affected by relative tangential sliding components of the wheel 10 relative to the fixed race 9, or in any case which is not affected by loss of contact, even accidental and instantaneous, between the wheel 10 and the race 9.

Another guarantee of the certainty of maintaining contact in all operating situations is the fact that the plate 33 may also be connected at a second connecting point, this time located on the same side as the wheel 10, and having elastic compression means, in particular a spring 11 designed to firmly press the wheel 10 against the race 9 even in the absence of the rotating motion of the thrust bearing 23 or, in any case, even at moments when the slow speed of rotation of the thrust bearing 23 could trigger centrifugal forces whose intensity is not sufficient to guarantee permanent contact between the wheel 10 and the race 9.

FIG. 3 and FIG. 4 together also show how the variator 5 has an adjusting mechanism, labelled 34 as a whole, which is equipped with a motor 35 that if necessary may be remote controlled. Activating the motor 35 allows very easy and rapid configuration of the variator 5 so as to provide—within its range of characteristic gear ratios the one most suited to the specific application for which the machine 1 is intended.

The invention described above is susceptible of 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.

Claims

1-13. (canceled)

14. A machine for packaging a product (2) in a wrapper formed by wrapping the product (2) with a film (8) of packaging material, said wrapping being achieved using a supplying apparatus (4) which supplies a continuous web of said film (8) and which can move, relative to the product (2), in such a way that it revolves around the product (2) and translates longitudinally relative to the product (2), the machine (1) comprising mechanical synchronising means (10, 5, 14), provided with at least a motion input shaft (6; 31), for synchronising the speed at which the film (8) is supplied with at least the apparatus (4) revolving speed around the product (2) and speed detecting means (9, 10, 5, 14) which are directly integrated with the mechanical synchronising means (10, 5, 14), the machine (1) being characterised in that said speed detecting means (9, 10, 5, 14) for detecting the instantaneous speed of rotation of the apparatus (4) comprise at least one fixed race (9) supported by the machine and at least one corresponding wheel (10) connected to the input shaft (6; 31) and held in contact with the race (9), the revolution of the apparatus (4) around the product (2) to be packaged causing the wheel (10) to roll on the fixed race (9) and consequent corresponding driving of mechanical synchronising means (10, 5, 14).

15. The machine according to claim 14, wherein the mechanical synchronising means (10, 5, 14) comprise a mechanical variator (5), supported by the movable supplying apparatus (4), moved by the motion input shaft (6; 31) and provided with a motion output shaft (7); the input shaft (6; 31) rotating with an angular speed correlated with the instantaneous peripheral speed of the revolving motion of the supplying apparatus (4) around the product (2), the output shaft (7) in contrast driving a unit (3) for unwinding the film (8) in such a way that the speed at which the film (8) is supplied is suitably correlated with the movable apparatus (4) revolving speed.

16. The machine according to claim 15, wherein said apparatus (4) is made to revolve around the product by drive means (24; 24m, 25, 26, 26t), the machine (1) comprising means (9, 10, 5, 14) for deriving the energy for supplying the film (8) of packaging material from the apparatus (4) drive means (24).

17. The machine according to claim 14, wherein it comprises friction means (27) which are operatively inserted between the wheel (10) and the race (9).

18. The machine according to claim 14, further comprising thrust means (11) for forcing said at least one wheel (10) into contact with said corresponding race (9).

19. The machine according to claim 18, wherein the thrust means (11) include the centrifugal force to which the mass of the variator (5) is subjected due to the revolving speed of the apparatus (4) around the product (2).

20. The machine according to claim 18, wherein the thrust means include spring elements (11) which are designed to press said at least one wheel (10) against the race (9).

21. The machine according to claim 15, further comprising a support (12) for the variator (5) which at a first connecting point pivots around a rotation pin (13) which is offset relative to a joining line ideally passing through the apparatus (4) centre of rotation and through the variator (5) centre of mass, and which at a second connecting point rests against the race (9) by means of said one or each wheel (10).

22. The machine according to claim 15, further comprising a belt drive (14) positioned between the variator (5) output shaft (7) and a shaft (6) of a unit (3) for unwinding film (8) from the apparatus (4).

23. The machine according to claim 21, wherein the support (12) comprises a plate (33) having two half-surfaces (28, 29) being monolithic and converging with each other at an angle, one of the half-surfaces (28, 29) supporting a variator (5) casing (30), the other half-surface (28, 29) supporting the variator (5) motion input shaft (7).

24. The machine according to claim 15, wherein the variator (5) has means for selecting the gear ratio which comprise an adjusting mechanism (34) that is motor-driven and can be remote controlled.