EP2939935A1

EP2939935A1 - Wrapping machine and wrapping method

Info

Publication number: EP2939935A1
Application number: EP15166073.5A
Authority: EP
Inventors: Mauro Cere'
Original assignee: Aetna Group SpA
Current assignee: Aetna Group SpA
Priority date: 2014-05-02
Filing date: 2015-04-30
Publication date: 2015-11-04
Anticipated expiration: 2035-04-30
Also published as: EP2939935B1; ES2615352T3

Abstract

A wrapping machine for wrapping a film (50) around a load (100) comprises an unwinding unit (60) of the film (50), the unwinding unit (60) and the load (100) being rotatable relative to one another around a winding axis (Z); the wrapping machine (1) comprises:
- first arm means (2) mobile in a first operating position (A1) in which said first arm means (2) is adjacent to and facing a wall (100a) of the load (100) and parallel to the winding axis (Z) so that at least one film strip (50a) is wrapped around said first arm means, the first arm means comprising first gripping means (5) and cutting means (6) respectively for gripping and cutting the film (50) at the end of a wrapping process of said load (100);
- second arm means (3) mobile in a second operating position (B1) in which said second arm means (3) is parallel and facing to the first arm means (2), which is arranged in said first operating position (A1), the second arm means (3) comprising second gripping means (7) mobile for gripping a film portion (F) of an terminal film section (50b), which is comprised between the load (100) and the unwinding unit (60), and for narrowing the film portion (F) in the form of a pleated strip and then for transferring said film portion to the first gripping means (5) in order to allow the cutting means (6) to cut the film portion (F) and obtain a first end flap (50c) of the film held by the first gripping means (5) and a second end flap (50d) of the film held by the second gripping means (7);
- third arm means (4) mobile in a third operating position (C1), in which said third arm means is parallel and adjacent to the first arm means (2), arranged in said first operating position (A1), and to said second arm means (3), arranged in said second operating position (B1), in order to divert the terminal film section (50b) so as to allow the second gripping means (7) to grip the film portion (F) irrespective of a size and/or a position of the load (100);
the first arm means (2) are movable so as to disengage from the film strip (50a) in order to insert and then release the first end flap (50c) of the film between the film strip (50a) and the wall (100a) of the load (100).

Description

The invention concerns to machines and methods for wrapping a load with a film made of stretchable plastics material and, in particular, it relates to a wrapping machine capable to making and fix to the load an end flap of the film at the conclusion of the respective wrapping process. The invention further relates to a wrapping method for making and then fixing to the load an end flap of the film at the conclusion of the wrapping process.
In the known wrapping machines the film is unwound from a reel supported by an unwinding unit and is wrapped around a load, typically made of a group of products arranged on a pallet, so as to form a series of interlaced strips or bands, thanks to the combination of a motion of the unwinding unit along a vertical direction and the relative rotation between said unwinding unit and the load.
In wrapping machines provided with a rotating table that supports the load, the latter is rotated around a vertical winding axis, while the unwinding unit is moved vertically with an alternate motion.
In wrapping machines with horizontal rotating ring or with rotating arm the product remains motionless during the wrapping, while the unwinding unit is moved in relation to the latter both in rotation around the vertical winding axis and in translation along the latter.
In wrapping machines with vertical rotating ring the product is moved through the ring during the wrapping, while the unwinding unit is fixed to the ring and rotated with the latter around the horizontal winding axis.
The unwinding unit supports a film reel and typically comprises a couple of pre-stretching rollers, which unwind from the reel the film and stretch or extend the latter, and one or more return rollers, which diverts the film towards the load.
At the end of the wrapping, namely when the load is wrapped with an established number of interlaced and overlapped stripes of film, the relative rotation between the unwinding unit and the load is stopped in order to cut the film and fix a so obtained end flap to the load.
There are known wrapping machines provided with means which allow gripping the film at an area between the unwinding unit and the load, cutting the film and pressing the so obtained against the load, the end flap being fixed to the load thanks to the adhesiveness of the plastic material and the effect of applied compression.
Thus, the end flap of the film substantially leans and spreads on the wrapped load, without being locked by any constraint. Such end flap can therefore be detached fairly easily, for example owing to external factors such as dust, water, humidity, wind, etc., this causing an incomplete, or unstable, and not waterproof wrapping of the load.
In order to overcome this drawback there are known wrapping machines that comprise means capable to paste the end flap to the wrapped product. Such means requires the use of suitable and expensive devices that supply and distribute the glue. Proper application of the glue, however, is not easy to be performed and also does not ensure a secure and reliable joining over time.
There are also known wrapping machines and wrapping methods in which there is provided to weld together the film portions. In particular, an end portion of the film, suitably reduced in width for reducing the dimensions of the weld bead, is pressed by a welding element against another portion of film supported by an abutment element, previously inserted inside the film wrapping. In this manner, the two welded portions lock the film wrapping to the product. After welding, the end portion is separated by cutting from the film coming from the reel.
A drawback of this technical solution lies in that the welding sometimes cannot be executed properly, for example, because of a welding element malfunction or an abnormal arrangement of the film portions to be welded, this causing detachment of the end flap and thus, an incomplete, unstable and not watertight wrapping of the load. Furthermore, such technical solution cannot be used in the case of plastics films that are not completely and/or correctly weldable such as, for example, perforated plastics film or films in the shape of mesh or net.
WO 99/29573 discloses a wrapping machine for wrapping loads with a stretchable film comprising spacing means that can be positioned close to the load, in a finishing final step of the wrapping, so that part of at least one final wrapping loop of the film leans against said spacing means in order to form a pocket. The wrapping machine carriage is stopped in a predefined angular position and the tail end of the film is aligned and correctly placed with respect to main and secondary pliers. Cutting means subsequently cut the portion of film between the two pliers and the main pliers, which hold the head end of the film coming from the wrapping machine carriage, moves back into the rest position. The secondary pliers, which retains the tail end of the film, are inserted into the pocket and then said pliers are opened and extracted from the pocket together with the spacing means that formed the pocket so that the tail end of the film remains restrained and locked by friction in last loop of the winding that contracts due to memory effect.
An object of the present invention is to improve the known wrapping machines and wrapping methods and, in particular, the wrapping machines and methods arranged for making an end flap of the wrapping film made of plastic material and for fixing said end flap to a load at the conclusion of a wrapping process thereof.
Another object is to provide a wrapping machine and a wrapping method that allow to make and fix to the load in a stable and steady manner an end flap of the wrapping film without welding or gluing portions thereof.
A further object is to obtain a wrapping machine and a wrapping method that allow using any type of plastic material for the wrapping film, such as entire, perforated or mesh film. In a first aspect of the invention a wrapping machine is provided according to claim 1.
In a second aspect of the invention a wrapping method is provided according to claim 13.
Thanks to these aspects of the invention it is possible to obtain a wrapping machine and a wrapping method that allow making an end flap of a wrapping film and fixing in a stable and permanent manner said end flap to the load at the conclusion of the wrapping process. , As a matter of fact, the end flap is blocked between two subsequent wrapping strips of the film, without needing to weld and/or stick. Elasticity and adhesion strength of the film over the load guarantee a reliable and steady blocking of the end flap.
The wrapping machine and the wrapping method of the invention therefore allow using a film made of cold-stretchable plastic material of any type, such as entire, perforated or mesh film.
The lack of welding and sticking devices allow having means for fixing the end flap with a quite simple and cheap structure, with precise, effective and reliable operation.
The wrapping machine of the invention comprises arm means provided with gripping means that in a reliable and correct manner grips and narrows a film portion in the shape of folded or pleated strip, irrespective of the size and/or the position of the load with respect to an unwinding unit of the machine.
The invention will be better understood and implemented with reference to the attached drawings, which illustrate an exemplifying and non-limiting embodiment, wherein:

Figure 1 is a perspective bottom view of the wrapping machine of the invention provided with arm means to make and fix an end flap of the film;
Figure 2 is a partial front view of the wrapping machine of figure 1 showing the arm means in respective retracted positions;
Figure 3 is a perspective bottom view of the arm means of figure 1 in respective operating positions;
Figure 4 is an enlarged perspective view of first arm means of the machine of figure 1 provided with first gripping means and cutting means of the film;
Figure 5 is an enlarged perspective view of second gripping means of second arm means of the machine of figure 1;
Figures 6 and 7 are respectively a partial front view and a section view along the line VII-VII of figure 6 of the wrapping machine of figure 1 in an operating step in which the first arm means is in a first operating position;
Figures 8 and 9 are respectively a partial front view and a section view along the line IX-IX of figure 8 of the wrapping machine of figure 1 in another operating step in which the first arm means and the second arm means are in respective operating positions;
Figures 10, 11 and 12 are respectively a partial front view, a section view along the line XI-XI of figure 10 and an enlarged side view of the wrapping machine of figure 1 in a further operating step in which the arm means is in respective operating positions;
Figures 13 and 16 are front and side partial views of the wrapping machine of figure 1 in successive operating steps;
Figure 17 is a partial side view of the machine of the invention in another operating step;
Figure 18 is an enlarged rear view of gripping means of the film of the machine of the invention in a film transfer operating step;
Figures 19 to 21 are partial perspective views of the machine of the invention in successive operating steps of the end flap inserting.

With reference to figures 1 to 21, a wrapping machine 1 according to the invention is shown that is arranged for wrapping a film 50 of plastic material, in particular a cold stretchable film, around a load 100 constituted, for example, by a plurality of products or objects that are grouped on a pallet.
The wrapping machine 1 comprises an unwinding unit 60, which supports a reel 51 of said film 50 and pre-stretching and return rollers 52, of known type, for stretching or extending the film 50 unwound from the reel 51 and for diverting it toward the load 100. The unwinding unit 60 and the load 100 are rotatable relative to each other around a winding axis Z.
In the embodiment illustrated as a non-limiting example, the wrapping machine 1 is a ring-type wrapping machine and comprises a horizontal rotating ring 61, which supports the unwinding unit 60 and is rotatably supported around the winding axis Z, in particular vertically, by frame means 62, 63 of said wrapping machine 1. The frame means 62, 63 comprises first frame means 62, which rotatably supports the rotating ring 61 and second frame means 63, which slidably supports the first frame means 62 and the rotating ring 61, mobile parallel to the winding axis Z. In this manner, since the unwinding unit 60 is rotated around the winding axis Z and simultaneously is moved parallel to the winding axis Z, the film 50 can be wrapped in superimposed and interlaced bands or stripes around the load 100.
The wrapping machine 1 comprises first arm means 2 mobile in a first operating position A1 in which said first arm means 2 is adjacent to, and facing, a wall 100a of the load 100 and parallel to the winding axis Z so that at least a film strip 50a is wrapped around said first arm means 2. The first arm means 2 comprises first gripping means 5 and cutting means 6 respectively for gripping and for cutting the film 50 at the conclusion of a wrapping process of the load 100, as better disclosed in the following description.
The first arm means 2 is rotatably fixed to supporting means 10 of the machine so as to be mobile around a first axis X1 between said first operating position A1 and a first retracted position A2, in which said first arm means 2 is folded inside the supporting means 10 and spaced from the load 100 and/or from the film 50 and almost orthogonal to the winding axis Z. The first axis X1 is substantially orthogonal to the winding axis Z and horizontal with reference to the shown embodiment of the wrapping machine.
The first arm means 2 is rotated between the first operating position A1 and the first retracted position A2 by first actuator means 15. The first actuator means 15 comprises, for example, a respective pneumatic or electric linear actuator.
The wrapping machine 1 comprises second arm means 3, which is mobile in a second operating position B1 in which it is parallel and facing the first arm means 2 and is provided with second gripping means 7. Said second gripping means 7 is mobile along the second arm means 3, according to a first moving direction T1, and is arranged to grip a film portion F of a terminal film section 50b that is comprised between the load 100 and the unwinding unit 60, so as to narrow said film portion F, to form a pleated or folded strip and then to transfer the latter to the first gripping means 5. The film portion F, when retained by the first gripping means 5, can be cut by the cutting means 6 so as to obtain a first end flap 50c of the film, retained by the first gripping means 5, and a second end flap 50d of the film, retained by the second gripping means 7, as better explained in the following description.
Second arm means 3 is rotatably fixed to the supporting means 10 so as to be mobile around a second axis X2 between the second operating position B1 and a second disengagement position B2 in which second arm means 3 is folded inside the supporting means 10, spaced from the load 100 and/or from the film 50 and almost orthogonal to the winding axis Z. The second axis X2 is substantially orthogonal to the winding axis Z and horizontal with reference to the shown embodiment. In this embodiment of the wrapping machine 1, the second axis X2 is coincident with the first axis X1.
The second arm means 3 is rotated between the second operating position B1 and the second retracted position B2 by second actuator means 16. The second actuator means 16 comprises, for example, a respective pneumatic or electric type linear actuator.
The wrapping machine 1 comprises third arm means 4 mobile in a third operating position C1, in which said third arm means 4 is parallel and adjacent to the first arm means 2 and to the second arm means 3 and arranged to divert the terminal film section 50b so as to allow the second gripping means 7 to intercept and grip a film portion F, irrespective of a size and/or a position of the load 100.
The third arm means 4 is rotatably fixed to the supporting means 10 so as to be mobile around a third axis X3 between the third operating position C1 and a third retracted position C2 in which said third arm means 4 is folded inside the supporting means 10, spaced from the load 100 and/or the film 50 and almost orthogonal to the winding axis Z. The third axis X3 is substantially orthogonal to the winding axis Z and substantially horizontal, with reference to the illustrated embodiment.
The third arm means 4 is rotated between the third operating position C1 and the third retracted position C2 by third actuator means 17. The third actuator means 17 comprises, for example, a respective pneumatic or electric actuator linear.
As shown in the figures and explained in detail in the following description, the first arm means 2 is mobile so as to disengage from the film strip 50a and to insert and release the first end flap 50c of the film between said film strip 50a and the wall 100a of the load 100. Supporting means 10 comprises an open box-shaped element which defines a casing 65 inside which the actuator means 15, 16, 17 of the arm means 2, 3, 4 and said arm means 2, 3, 4 are fixed and housed in the respective retracted positions A2, B2, C2. The supporting means 10 is fixed to the frame means 62, 63. In particular, the supporting means 10 is slidably supported by the first frame means 62 so as to be movable along an approaching direction S1 that is substantially orthogonal to the winding axis Z and parallel to a supporting plane of the load 100 in order to arrange the arm means 2, 3, 4 in the correct position, adjacent to the wall 100a of the load, according to size and/or position thereof in the wrapping machine 1. The supporting means 10 is moved along the approaching direction S1 by actuator means of known type, fixed to the first frame means 62. The supporting means 10 is also mobile with the first frame means 62 along a lifting direction S2 that is parallel the winding axis Z.
The first gripping means comprises external pliers 5 that is mobile linearly and parallel to a longitudinal axis of the abutment arm 21 and is arranged for interacting with a lower portion of the further first end 21b of the abutment arm 21 so as to block the film portion F. The external pliers 5 are actuated by first motor means 25 between a respective open position, in which said external pliers 5 are spaced apart from the lower portion of the further first end 21b for allowing the film portion F to be inserted, and a respective closed position, in which said external pliers 5 abut the lower portion of the further first end 21b for blocking the film portion F.
The first motor means 25, comprising for example a respective pneumatic or electric linear actuator, is mounted inside the abutment arm 21 and moves the external pliers 5 through a connecting rod.
The cutting means comprises a cutting element 6 slidably contained in a housing 24 of the abutment arm 21 and mobile in a cutting position in which said cutting element 6 partially protrudes from the housing 24 so as to cut the film portion F, blocked by the first gripping means 5.
Second motor means 26, comprising for example a respective pneumatic or electric linear actuator, is mounted inside the abutment arm 21 for linearly moving the cutting element 6 by means of a respective connecting rod 27.
Second arm means 3 comprises a supporting arm 31, which has an elongated shape and is rotatably connected to the supporting means 10 at a second end 31 a and which slidably supports the second gripping means 7. The latter is mobile along the supporting arm 31 according to the first moving direction T1 between a first working position D1, wherein second gripping means 7 is disengaged from the film 50, and a second working position D2, wherein said second gripping means 7 is engaged to the film portion F and substantially faces the first gripping means 5.
With particular reference to figure 5, the gripping means 7 comprises a couple of pliers 20, 20' suitable to grip the film portion F and carriage means 18, 19 slidably fixed to the supporting arm 31 and slidably supporting the pliers 20, 20'. In particular, the gripping means 7 comprises first pliers 20 and second pliers 20', which are substantially identical and arranged parallel and spaced apart each other.
The carriage means comprises a first carriage 18, which is slidably mounted on the supporting arm 31 and is mobile along the latter between the first working position D1 and the second working position D2, and a second carriage 19, which supports the pliers 20, 20' and is mobile transversally to the supporting arm 31 for allowing the pliers 20, 20' to transfer the film portion F in the form of pleated strip to the first gripping means 5.
The first carriage 18 is driven along the supporting arm 31 by third motor means 33 comprising, for example, a respective pneumatic or electric linear actuator.
The second carriage 19 is transversally moved in a direction substantially orthogonal to the winding axis Z by fourth motor means 28 comprising a respective pneumatic or electric linear actuator.
The pliers 20, 20' comprise respective first jaws 20a and second jaws 20b and are independently movable between a respective open position P1 and a respective closed position P2. In the open position P1 the pliers 20, 20' are capable to grab, drag, and narrow the film portion F, when the first carriage 18 is moved along the supporting arm 31 between the first working position D1 and the second working position D2. More precisely, the first jaws 20a and the second jaws 20b are spaced apart for enabling the first jaws 20a to engage, drag and narrow the film portion F. In the closed position P2, the pliers 20, 20' tighten the film portion F; more precisely, the second jaws 20b of the pliers 20, 20' are closed against the first jaws 20a so as to tighten the film portion F.
The first jaws 20a are fixed and rigidly connected to the second carriage 19, while the second jaws 20b are mobile, rotatably fixed to the second carriage 19 so as to rotate around a common rotating axis between the open position P1 and the closed position P2. The second jaws 20b are rotatably actuated by fifth motor means 29 comprising respective pneumatic or electric linear actuators that are fixed to said second carriage 19 and operate on the second jaws 20b. In this manner, the first pliers 20 and second pliers 20' can be opened and closed separately and independently.
The third arm means 4 comprises a return arm 41, which comprises a third end 41a rotatably connected to the supporting means 10 and a terminal part 42 that is opposite to the third end 41 a and is mobile linearly, in particular is retractable in a retracted position E1 in order to not interfere with the film 50 when the second gripping means 7 transfers the film portion F in the form of pleated s to the first gripping means 5. More precisely, the terminal part 42 of the return arm 41 is moved by fourth actuator means housed inside the return arm 41 between an extended position E2, in order to detect and divert the terminal film section 50b towards second gripping means 7, and the retracted position E1.
The functioning of the wrapping machine 1 of the invention provides at the end of wrapping of the load 100 with the film 50 a sequence of operating steps, schematically shown in figures 2, 6-21, during which the first film end flap 50c is made to be fixed to the load 100.
In a first step, the arm means 2, 3, 4 are in the respective retracted positions A2, B2, C2, namely spaced apart from the product 100 and the film 50 for allowing the unwinding unit 60 to rotate and wrap the product 100 with a predefined number of strips or bands of film 50 unwound from the reel 51 (Figure 2).
In a second step, the rotation of the unwinding unit 60 is stopped or slowed down - in particular rotation of rotating ring 61 is stopped or slowed down - and the first arm means 2 is rotated in the first operating position A1, for example counterclockwise with reference to the view of figure 6. It is provided that the supporting means 10 can be preventively moved along the approaching direction S1 for bringing the first arm means 2 nearer to the side wall 100a of load 100 (Figures 6 and 7).
The unwinding unit 60 - eventually rotated again after the stop - then put down at least one film strip 50a on the load 100 and on the first arm means 2. The latter spaces apart, therefore, from the wall 100a a section B of said film strip 50a so as to create a cavity V (Figure 7).
In a third step, third arm means 4 is rotated in the third operating position C1, for example, counterclockwise with reference to the view of Figure 8, with the terminal part 42 in the extended position E2 so as to intercept the terminal film section 50b, which is interposed between the load 100 and the unwinding unit 60, and to divert the film portion F close to the first arm means 2 (Figures 8 and 9), arranged to be, in a subsequent fourth step, abutted and gripped by the second gripping means 7, independently of a size and/or a position of said load 100.
In a fourth step (Figures 13 and 14), with the unwinding unit 60 motionless, the second arm means 3 is rotated in the second operating position B1, for example clockwise with reference to the view of Figure 10, so as to be positioned opposite to the first arm means 2. The film portion F is interposed between the first arm means 2 and the second arm means 3. The second gripping means 7, arranged in the first working position D1 is therefore moved along the supporting arm 31 in the second working position D2 in order to grip and drag down the film portion F. More precisely, the pliers 20, 20' of the second gripping means 7, arranged in the open position P1, are moved with the carriage means 18, 19 along the supporting arm 31 in the first moving direction T1 so as to grip a upper first longitudinal edge F1 of said film portion F and drag it down, transversely to the unwinding direction of the film 50, towards an opposite lower second longitudinal edge F2. The first jaws 20a of the pliers 20, 20' narrow and compact the portion F until a pleated or folded strip of film is formed, which, in the second working position D2 of the second gripping means 7, is blocked tightly by the pliers 20, 20' arranged in the closed position P2, the second jaws 20b being in abutment with the first jaws 20a.
In a successive fifth step (Figures 15 and 16), the second gripping means 7 are moved transversally to the supporting arm 31, in particular orthogonally to the latter along a second moving direction T2, toward the first arm means 2, so as to insert the pleated strip of film inside the first gripping means 5 that is arranged in the respective open position.
In order to enable second gripping means 7 interacting with the first gripping means 5 and transferring the film portion F, the terminal part 42 of the return arm 41 of third arm means 4 is moved linearly in the retracted position E1, inside the return arm 41.
Then the external pliers 5 of first gripping means are moved in the respective closed position so as to block the film portion in the form of pleated strip against the lower portion of the further first end 21b of the abutment arm 21. Therefore, the cutting means 6 is actuated in order to cut the film portion F (Figures 17 and 18).
The two flaps of film so obtained are retained by the gripping means 5, 7. In particular, a first end flap 50c is blocked by the first gripping means 5 and a second end flap 50d is blocked by the second gripping means 7. More precisely, the second end flap 50d is retained by the first pliers 20 of the second gripping means 7, the second pliers 20' being afterward opened in order to release the first end flap 50c retained by the first gripping means 5.
In a following sixth step, the second gripping means 7 is moved transversely along the second moving direction T2 moving away from the first gripping means 5 so blocking the second end flap 50d of the film coming from the reel 51 (Figure 19).
In a seventh step, the first arm means 2, the second arm means 3 and the third arm means 4 are moved along the lifting direction S2 and moved away from the load 100. In this manner, the first end flap 50c of film, which is retained by the first gripping means 5 of the first arm means 2, is inserted into the cavity V through a lower inlet V1. In particular, the second frame means 62 is moved upwards in the lifting direction S2, said second frame means 62 slidably supporting the supporting means 10 to which the arm means 2, 3, 4 are connected.
During the progressive lifting, while the abutment arm 21 of first arm means 2 disengages progressively from the cavity V, the first end flap 50c, which is retained by the first gripping means 5, is instead further inserted into the cavity V and partially unwound and/or stretched. At the same time, the section B of the film strip 50a is gradually released by the abutment arm 21 so as to block the first end flap 50c of film against the side wall 100a of the load 100.
When the abutment arm 21 has been lifted up to an height where the first end flap 50c of film has a portion or tail of suitable length which is interposed between the side wall 100a and the film strip 50a, the first gripping means 5 release the first end flap 50c of film (Figure 20).
Once completely disengaged from the section B of the film strip 50a, the arm means 2, 3, 4 are rotated around their respective axes X1, X2, X3 in the retracted positions A2, B2, C2.
Alternatively, the above mentioned seventh step can be carried out without lifting the supporting means 10 (or the second frame means 62) along the lifting direction S2, but rotating the first arm means 2 around the first axis X1 in the first retracted position A2 (and rotating the second arm means 3 and the third arm means 4 around their respective axes X2, X3 in the retracted positions B2, C2). Also in this case, while the abutment arm 21 progressively disengages from the cavity V, the first end flap 50c of the film, blocked and retained by the first gripping means 5, is gradually inserted inside the cavity V and blocked between the section B of the film strip 50a and the side wall 100a.
Thanks to the wrapping machine of the invention is therefore possible to make an end flap of a wrapping film and fix in a stable and permanent manner said end flap to the load 100 at the conclusion of the wrapping process. In fact, the end flap is blocked between two successive wrapping strips of film, without needing welding and/or sticking. The elasticity and adhesion strength of the film around the load guarantee a reliable and stable block of said end flap.
The wrapping machine of the invention therefore allows using a film made of cold-stretchable plastic material of any type, such as entire, perforated or mesh film.
Lack of welding and sticking devices allows having fixing means of the end flap having a relatively simple and inexpensive structure, with a precise, effective and reliable operation. To be noted that, thanks to the third arm means 4, the second gripping means 7 of second arm means 3 is capable to grip and narrow the film portion F in the shape of a pleated or folded strip in a reliable and correct manner, irrespective of the size and/or the position of the load 100 with respect to the unwinding unit 60.
As shown in figures 8 to 11, which illustrate with a continuous line a big size load 100 and, with a dotted line, a smaller size load 100', the third arm means 4 diverts the terminal film section 50b comprised between the load 100 and the unwinding unit 60 so that the film portion F is always interposed between the first arm means 2 and second arm means 3 and, in particular, facing the second gripping means 7. The second gripping means 7, which are moved along the supporting arm 31, is always cable to grip the upper first longitudinal edge F1 of the film portion F and drag it to the opposite lower second longitudinal edge F2 so as to form the pleated strip of film.
In the embodiment described and shown in the figures, the wrapping machine 1 is a horizontal rotating ring machine.
The wrapping machine of the invention can however also be of vertical rotating ring machine, the supporting means 10 being in this case fixed to the frame means which rotatably supports the ring that rotates around a horizontal axis.
The wrapping machine of the invention can also be a machine with rotating arm or arms and can comprise unwinding unit that is slidably mounted on an arm rotatable around the winding axis Z. The unwinding unit is also linearly mobile on the rotating arm along a direction parallel to the winding axis Z.
In this case, the supporting means 10 and the arm means 2, 3, 4 are fixed to moving means of the load, typically comprising roller conveyor means suitable for supporting the load 100 and enabling the latter to entry in and/or to exit from a wrapping operating zone. In particular, the supporting means 10 can be fixed to a side of the moving means so that the arm means 2, 3, 4 can be rotated upwards between respective retracted positions A2, B2, C2 and respective operating positions A1, B1, C1.
In the retracted positions A2, B2, C2, the arm means 2, 3, 4 are arranged substantially horizontal, parallel to, and below, a supporting plane defined by said moving means, in order to not interfere with the wrapping of the film 50 around the load 100. In the respective operating positions A1, B1, C1, the arm means 2, 3, 4 are arranged vertical and parallel to the winding axis Z in order to interact with the film 50.
The operation of the rotating arm wrapping machine at the conclusion of the wrapping of the load 100 with the film 50 provides the same sequence of operational steps, as above described for ring wrapping machine, to make the first end flap 50c of the film to be fixed to the wrapped load 100.
The wrapping machine of the invention can also be a rotating table wrapping machine and comprising a table, which supports and rotates the load around the winding axis Z, and a fixed column, which slidably supports the unwinding unit, mobile along a direction that is parallel to the winding axis Z.
The supporting means 10 and the arm means 2, 3, 4 are fixed in this case at a side of the rotating table or directly on the rotating table so as to be, anyway, adjacent to and facing the load during the wrapping. In particular, the supporting means 10 are fixed so that the arm means 2, 3, 4 are rotatable upward between the respective retracted positions A2, B2, C2, and the respective operating positions A1, B1, C1. In the retracted positions A2, B2, C2, the arm means 2, 3, 4 are arranged substantially horizontal, parallel in order to not interfere with the wrapping of the film 50 around the load 100. In the respective operating positions A1, B1, C1 the arm means 2, 3, 4 are arranged vertical and parallel to the winding axis Z in order to interact with the film 50.
The operation of the rotating table wrapping machine at the conclusion of the wrapping of the load 100 with the film 50 provides the same sequence of operational steps, above described for the ring or rotating arm wrapping machine for making the first end flap 50c of the film to be fixed to the load 100.
The wrapping method of the invention for making and fixing an end flap 50c of a film 50 wrapped with strips around a load 100 using the wrapping machine 1 above described, comprises the following steps:

wrapping the load 100 with a defined number of overlapping and/or interlaced strips of film (50);
spacing a section B of at least one film strip 50a from a wall 100a of said load 100 in order to carry out a cavity V by first arm means 2 of said wrapping machine 1, provided with first gripping means 5 and cutting means 6 and arranged in a first operating position A1;
diverting a terminal film section 50b, which is comprised between said load 100 and an unwinding unit 60 of said wrapping machine 1 by third arm means 4 so as to position a film portion F of said terminal film section 50b substantially facing said first arm means 2 and second arm means 3 of said wrapping machine 1;
gripping and narrowing the film portion F up to form a pleated strip of film at an inlet V1 of said cavity V by second gripping means 7 of second arm means 3;
transferring the film portion F in the form of a pleated strip to the first gripping means 5;
cutting with cutting means 6 the film portion F for obtaining a first end flap 50c of the film retained by the first gripping means 5 and a second end flap 50d of the film retained by second gripping means 7;
inserting the first end flap 50c of the film inside the cavity V by moving the first arm means 2, the latter progressively disengaging from the cavity V retaining the first end flap 50c of the film;
releasing the first end flap 50c of the film when a portion thereof is interposed between the wall 100a and the film strip 50a, the first end flap 50c of the film remaining blocked between the film strip 50a and the wall 100a.

The method provides to space out the section B of the film strip 50a by placing the first arm means 2 in the first operating position A1, where it is adjacent to the wall 100a, and then by wrapping the film strip 50a around the load 100 and around the first arm means 2, the latter being interposed between the wall 100a and the film strip 50a so as to form the cavity V.
It is also provided that said gripping and narrowing the film portion F comprises clasping a first longitudinal edge F1 of the film portion F through the second gripping means 7, moving the first longitudinal edge F1 towards a second longitudinal edge F2 of the film portion F in order to narrow the latter in the shape of a pleated or folded or wrinkled strip. In order to disengage the cavity V by moving the first arm means 2 it is provided to linearly move the latter along a lifting direction S2 and/or to rotate the first arm means 2 around a respective first axis X1 in a first retracted position A2.

Claims

Wrapping machine for wrapping a film (50) around a load (100) comprising an unwinding unit (60) of said film (50), said unwinding unit (60) and said load (100) being rotatable relative to one another around a winding axis (Z), said wrapping machine (1) comprising:
- first arm means (2) mobile in a first operating position (A1) in which said first arm means is adjacent to and facing a wall (100a) of said load (100) and parallel to said winding axis (Z) so that at least one film strip (50a) is wrapped around said first arm means, said first arm means (2) comprising first gripping means (5) and cutting means (6) respectively to grip and to cut said film (50) at the end of a wrapping process of said load (100);

- second arm means (3) mobile in a second operating position (B1), in which said second arm means is parallel to and facing said first arm means (2), which is arranged in said first operating position (A1), said second arm means (3) comprising second gripping means (7) mobile for gripping a film portion (F) of a terminal film section (50b), which is comprised between said load (100) and said unwinding unit (60), and for narrowing said film portion (F) in the form of a pleated strip and then transferring said film portion (F) to said first gripping means (5) in order to allow said cutting means (6) to cut said film portion (F) and obtain a first end flap (50c) of the film held by said first gripping means (5) and a second end flap (50d) of the film held by said second gripping means (7);

- third arm means (4) mobile in a third operating position (C1), in which said third arm means is parallel and adjacent to said first arm means (2), arranged in said first operating position (A1), and to said second arm means (3), arranged in said second operating position (B1), in order to divert said terminal film section (50b) so as to allow said second gripping means (7) to grip said film portion (F) irrespective of a size and/or a position of said load (100);
said first arm means (2) being movable so as to disengage from said film strip (50a) in order to insert and then release said a first end flap (50c) of the film between said film strip (50a) and said wall (100a) of the load (100).
Machine according to claim 1, comprising supporting means (10) for rotatably supporting said first arm means (2) around a first axis (X1), said second arm means (3) around a second axis (X2) and said third arm means (4) around a third axis (X3), said first axis (X1), the second axis (X2) and the third axis (X3) being parallel and substantially perpendicular to said winding axis (Z).
Apparatus according to claim 1 or 2, comprising actuator means (15, 16, 17) for rotating said arm means (2, 3, 4) between said respective operating position (A1, B1, C1) and respective retracted position (A2, B2, C2), in which said arm means (2, 3, 4) is spaced from said load (100) and/or from said film (50) and substantially orthogonal to said winding axis (Z), in particular housed inside supporting means (10).
Apparatus according to any preceding claim, wherein said first arm means (2) comprises an abutment arm (21) provided with a first end (21a) that is rotatably fixed to supporting means (10) and with an opposite further first end (21b) that supports said first gripping means (5) and said cutting means (6).
Apparatus according to claim 4, wherein said first gripping means comprises external pliers (5) that are mobile and arranged to interact with a lower portion of said further first end (21b) of said abutment arm (21) so as to block said film portion (F) and wherein said cutting means (6) comprises a cutting element that is slidably contained in a housing (24) of said abutment arm (21) and movable in a cutting position in which said cutting element partially protrudes from said housing (24) to cut the film portion (F) that is tightened by said first gripping means (5).
Apparatus according to any preceding claim, wherein said second arm means (3) comprises a supporting arm (31) provided with a second end (31a) that is rotatably connected to supporting means (10) and slidably supports said second gripping means (7), which is mobile along said supporting arm (31) along a first moving direction (T1), in particular between a first working position (D1), in which said second gripping means (7) is disengaged from said film (50), and a second working position (D2) in which said second gripping means (7) engages said film portion (F) and substantially faces said first gripping means (5).
Machine according to claim 6, wherein said second gripping means (7) comprises a couple of pliers (20, 20') suitable for griping said film portion (F) and carriage means (18, 19) that are slidably fixed to said supporting arm (31) and slidably supporting said pliers (20, 20').
Machine according to claim 7, wherein said carriage means comprise a first carriage (18) slidably connected to said supporting arm (31) and mobile along said first moving direction (T1) and a second carriage (19) supporting said pliers (20, 20') and mobile transversely to said supporting arm (31) along a second moving direction (T2) in order to allow said pliers (20, 20') transferring said film portion (F) in the form of a pleated strip to said first gripping means (5).
Machine according to claim 7 or 8, wherein said second gripping means (7) comprises first pliers (20) and second pliers (20') that are arranged parallel and spaced apart, and are independently drivable between respective open positions (P1), in which they grip, drag and narrow said film portion (F), when said first carriage (18) is moved along said supporting arm (31), and respective closed positions (P2) in which said pliers (20, 20') tighten said film portion (F).
Machine according to any preceding claim, wherein said third arm means (4) comprises a return arm (41) provided with a third end (41a) that is rotatably connected to supporting means (10) and with a terminal part (42) which is opposite to said third end (41a) and mobile, in particular retractable in a retracted position (E1) in order to not interfere with said film (50) when said second gripping means (7) transfers said film portion (F) to said first gripping means (5).
Machine according to any preceding claim, comprising frame means (62, 63) for rotatably supporting said unwinding unit (60) and supporting means (10) arranged for rotatably supporting said arm means (2, 3, 4), said supporting means (10) being slidably fixed to said frame means (62, 63) and mobile along an approaching direction (S1) that is substantially perpendicular to said winding axis (Z) and said wall (100a) of said load (100).
Machine according to any preceding claim, comprising moving means for supporting and moving said load (100) and supporting means (10) for rotatably supporting said arm means (2, 3, 4), said supporting means (10) being fixed to said moving means.
Wrapping method for making and fixing an end flap of a film (50) that is wrapped in strips around a load (100) by a wrapping machine (1) according to any preceding claim, comprising:
- wrapping said load (100) with a defined number of overlapping and/or interlaced strips of film (50);

- spacing a section (B) of at least one film strip (50a) from a wall (100a) of said load (100) so as to carry out a cavity (V) by first arm means (2) of said wrapping machine (1) provided with first gripping means (5) and cutting means (6) and arranged in a first operating position (A1);

- diverting a terminal film section (50b) which is comprised between said load (100) and an unwinding unit (60) of said wrapping machine (1) by third arm means (4) so as to position a film portion (F) of said terminal film section (50b) substantially facing said first arm means (2), arranged in a first operating position (A1), and second arm means (3), arranged in a second operating position (B1), of said wrapping machine (1);

- gripping and narrowing said film portion (F) so as to form a pleated strip at an inlet (V1) of said cavity (V) by second gripping means (7) of said second arm means (3);

- transferring said film portion (F) in the form of a pleated strip to said first gripping means (5);

- cutting with said cutting means (6) said film portion (F) for obtaining a first end flap (50c) of the film held by said first gripping means (5) and a second end flap (50d) of the film held by said second gripping means (7);

- inserting said first end flap (50c) of the film inside said cavity (V) by moving said first arm means (2), the latter progressively disengaging from the cavity (V) by holding said first end flap (50c) of the film;

- releasing said first end flap (50c) of the film when a portion thereof is interposed between said wall (100a) and said film strip (50a), said first end flap (50c) of the film remaining blocked between said film strip (50a) and said wall (100a).
Method according to claim 13, wherein said spacing said section (B) of said film strip (50a) comprises positioning said first arm means (2) in said first operating position (A1) adjacent to said wall (100a), wrapping said film strip (50a) around said load (100) and said first arm means (2), said first arm means (2), which is interposed between said wall (100a) and said film strip (50a), forming said cavity (V).
Method according to claim 13 or 14, wherein said gripping and narrowing comprises hooking by said second gripping means (7) a first longitudinal edge (F1) of said film portion (F), moving said first longitudinal edge (F1) towards a second longitudinal edge (F2) of said film portion (F) along a first moving direction (T1) in order to narrow the film portion (F) in the form of pleated strip.