EP2452881A1

EP2452881A1 - Vertical winding apparatus for packaging of pallet loads with films of plastic material of different heights

Info

Publication number: EP2452881A1
Application number: EP11188317A
Authority: EP
Inventors: Maurizio Orfano
Original assignee: Officina Meccanica Sestese SpA
Current assignee: Officina Meccanica Sestese SpA
Priority date: 2010-11-10
Filing date: 2011-11-08
Publication date: 2012-05-16
Anticipated expiration: 2031-11-08
Also published as: IT1403246B1; PT2452881E; ITMI20102086A1; EP2452881B1; ES2426867T3; DK2452881T3

Abstract

It is disclosed a vertical winding apparatus for the packaging of pallet loads progressing sequentially along a transport path (Y-Y), to a packaging station (X-X) arranged transversally to said transport path (Y-Y). The apparatus comprises two carts (TR, TR') for supporting a respective group of vertical-axis reels (B1 .. Bn; B1' .. Bn') of plastic film (5) of different quality/heights, said carts (TR, TR') being arranged at the two sides of the transport path (Y-Y) and being apt to carry a pair of reels of equal quality/height (B1, B1' ; . . . ; Bn, Bn'), according to choice, in correspondence of said packaging station (X-X), as well as a pair of carrying means (P) arranged in said packaging station (X-X) and each one moving from a position next to one of said support carts (TR, TR') to a central welding position and vice versa, each one of said carrying means (P) being apt to accompany in said movement one edge of the film (5) of said pair of reels (B1, B1' ; . . . ; Bn, Bn'), and it furthermore comprises, associated with each reel:
- a gripper (S) for the drawing of said edge of the film (5) carried by the reel (B1, B1' ; . . . ; Bn, Bn'), said gripper (S) being capable of being connected to and released from said carrying means (P),
- guiding and detecting means (3, 3a, 4, 6) of said film (5), comprising at least one dancer roll means (3) moving under the action of the tension in said film (5) against the action of elastic means, and
- a tensioning assembly (6, 7, 8, 9) comprising a roll driven in rotation acting on the periphery of said reel (B1, B1' ; . . . ; Bn, Bn'), the action of which can be modulated and controlled according to the position taken up by said dancer roll (3).

Description

Field of the Invention

The present invention concerns an improved, vertical winding apparatus for the packaging of pallet-stacked loads. More precisely, it is an apparatus which allows to package stacks of products which arrive in sequence at a packaging station, but which have sizes which may differ greatly from one another, and which hence require the use of different-height films of plastic material, suited precisely to the sizes of the products to be packaged.

Background Art

The prior art already proposes a packaging procedure which provides to cover the lateral surface of a pallettised load with a plastic material film, keeping the winding film vertical and applying the film while the load is going through the machine. More in particular, according to the prior art, two webs of wrapping film - of a height substantially equivalent to that of the load - are kept on a vertical plane and supplied starting from two respective, opposite reels, arranged at the sides of the load running path with their own axis vertical, i.e. perpendicular to the supporting plane of the load; the ends of the two webs are brought close to each other and welded to each other to form a sort of vertical "curtain" which crosses the load running path; when a load progresses, first the two parts of webs forming a single, continuous curtain are applied on the front of the load, then the webs are guided on the two sides of the load and finally on the rear surface thereof, where a further joint is performed by welding.
On the rear side of the load two vertical joining lines are preferably performed by welding, between which a vertical cut is carried out to severe the packaging just formed on a load from the "curtain" which is left formed for the packaging which will be formed on the subsequent load. Wrapping machines of this type are known from documents FR-2,212,263 in the name of THIMON or EP-1,174,343 or US-6,474,051 in the name of MSK-Verpackung.
Since this technique provides the execution of a welding both on the front and on the rear of a load to be packaged, it can be used very well in the case of use of different-height wrapping films - each time suited to the height of the load to be packaged - provided a change of reels is scheduled in the phase of changing over from packaging a load of a first size to packaging a subsequent load of a very different size from the first one. An apparatus capable of performing this change of reels and the corresponding film welding and cutting operations is disclosed in Italian patent no. 1,356,529 in the name of the same Applicant, the contents of which are hereby entirely recomprised by reference, for a better understanding of the invention.
The packaging machine disclosed in this patent employs a pair of transport carts for packaging film reels, arranged on both sides of the transport line of the pallet loads, and capable of carrying each time a pair of supply reels of identical size in correspondence of the packaging station. In the cited Italian patent no. 1,356,529 a first solution with rectilinear carts and a second solution with revolving carts are provided; in the following description reference is made to a revolving cart, but it is clear that the teaching of the present invention applies to any other type of cart.
In IT 1,356,529 a general description of the reel replacement system is provided, but specific film management problems are not addressed, which at that time had not been highlighted yet. In particular, it has been detected that during reel replacement, space for improvement still exists in the film rewinding operations and in the operations for the subsequent resetting of the correct tension of the packaging web.
As a matter of fact, on the one hand, the need for rewinding the film on a no-longer-operative reel exists, preventing the film from sliding downwards, disassembling itself or ending up out of reach of the drawing gripper; on the other hand, it is required to bring the film quickly back to its correct tension when the same reel is made operational again.

Summary of the Invention

It is therefore an object of the present invention to solve the problem, remained unsolved up until today, of ensuring, on the one hand, a perfect supply of the packaging film from the respective supply reel during the working phase but, on the other hand, also a perfect retaining of the packaging film on the supply reels which are in a home position.
This object is achieved with an apparatus having the features mentioned in claim 1. The dependent claims describe preferred features of the invention.
In particular, according to a first aspect of the invention, it is provided a vertical winding apparatus for the packaging of pallet loads progressing sequentially along a transport path, to a packaging station arranged transversally to said transport path, of the type comprising two carts for supporting a respective group of vertical-axis reels of plastic film of different quality/heights (i.e different nature), said carts being arranged at the two sides of the transport path and being apt to carry a pair of reels of equal quality/height, according to choice, in correspondence of said packaging station, as well as a pair of carrying means arranged in said packaging station and each one moving from a position next to one of said support carts to a central welding position and vice versa, each one of said carrying means being apt to accompany in said movement one edge of the film of said pair of reels, wherein it furthermore comprises, associated with each reel:

a gripper for the drawing of said edge of the film carried by the reel, said gripper being capable of being connected to and released from said carrying means,
guiding and detecting means of said film, comprising at least one dancer roll means moving under the action of the tension in said film against the action of elastic means, and
a tensioning assembly comprising a roll driven in rotation acting on the periphery of said reel, the action of which can be modulated and controlled according to the position taken up by said dancer roll.

According to a further aspect of the invention, said guiding and detecting means comprise a rocker arm, carrying at the free end thereof a dancer roll acting as deflector means of the film, said rocker arm oscillating under the thrust, on one side, of a tensioning spring and, on the other side, of the traction of the film which unwinds or winds back up on the reel. Preferably, said dancer roll can take up two extreme positions, the exceeding of which produces a control signal for said tensioning assembly.
According to a further aspect, the deflection path of said film on said dancer roll comprises at least a first portion, between reel and roll, and at least a second portion, between roll and said gripper, said two portions forming a flattened-S-shaped path. Preferably the deflection path of said film on said dancer roll comprises at least a third portion, between the exit from the reel and a stationary deflector roll, which precedes the portion towards the dancer roll in the progression direction of the film to the load to be packaged.
According to an additional aspect, said roll driven in rotation is mounted swinging between a position away from the reel and a position in friction contact against the peripheral surface of the reel.
Said roll driven in rotation is preferably mounted on a rocker arm so as to be brought in contact with the peripheral surface of the reel, when it is necessary to reduce film tension, or to be moved away from said reel surface, respectively, when it is necessary to increase film tension.
Advantageously, said tensioning assembly can be operative in an equivalent manner both in a first rotation direction of the reel, during film supply, and in a second, opposite direction, during the rewinding of the reel.

Brief Description of the Drawings

Further features and advantages of the invention will appear in any case more evident from the following detailed description of a preferred embodiment, given by way of a nonlimiting example and illustrated in the attached drawings, wherein:

fig. 1 is a schematic top plan view of a packaging station according to the present invention; and
fig. 2 is a view, similar to the one of fig. 1, which shows only the detail of the film tensioning system.

Detailed Description of the Preferred Embodiment

As shown by the drawings, the packaging apparatus having changeable reels according to the present invention is of the type as the one shown in Italian patent no. 1,356,529 . It is a packaging apparatus, arranged transversally to a transport line Y-Y of a series of loads C, provided with a pair of reel-supporting carts TR, TR', having a revolving arrangement. Each of these carts TR and TR' consists of a rotating platform, on the periphery of which is mounted a group of film reels B1, B2, B3, B4, B5, and B1', B2', B3', B4', B5', respectively, mounted freely rotating on vertical-axis pins 1, each reel differing from the others by the height or quality of the plastic packaging material film. These revolving carts TR, TR' are capable of carrying - in correspondence of the packaging station defined by line X - each time a desired supply reel in front of the operative line through which the load to be packaged is going to pass.
As shown by the top plan view of fig. 1, a load C to be packaged progresses in the direction shown by arrow F along a path schematised by line Y-Y to reach the proximity of a packaging station schematised by transversal line X-X and by a pair of transport carriers P and P'. The transport carts are shown here in a home position, but they are mounted so as to be able to slide along line X-X, one transversally to line Y-Y, in the direction of the other and vice versa, in the way better described in the above-mentioned Italian patent no. 1,356,529 .
As already stated, the working procedure of this apparatus directed to lay a curtain of vertical plastic web across the running direction of load C and to wrap the latter on all sides

is known from the above-mentioned Italian patent no. 1,356,529 , therefore further explanations in the merit are not deemed necessary.

The support spindles 1 of reels B are mounted, adjustable in position, on carrier arms 2 (seen better in fig. 2), integral with rotating supports TR and TR', respectively, and radially arranged with respect to the centre thereof.
Carrier arms 2 form, together with second arms 2' arranged square-like, a support also for a manoeuvring arm 4, oscillating around a vertical axis 4'. With manoeuvring arm 4 a tensioning spring (not shown) is associated, which tends to cause the arm to oscillate in a clockwise direction (with respect to the plane of the drawing), with a determined thrust bias, which may be adjusted in a manner known per se.
At the end opposite to axis 4', arm 4 carries a dancer roll 3, which represents a transmission and tensioning roll of film 5 unwound from reel B1. This film unwinds tangentially from reel B1, i.e. in a direction corresponding to an anti-clockwise rotation of the reel. Unwinding from reel B1, film 5 runs on a first, stationary deflector roll 3a, then on dancer roll 3, and finally from said roll to a transmission gripper S.
This transmission gripper S is mounted at the end of arm 2' in a releasable manner, so that it can be taken from carrier P - in the way described in the above-mentioned patent no. 1,356,529 - and drawn, together with the initial edge of the packaging film, towards the centre of the packaging station, represented by longitudinal axis Y-Y.
Upstream of the displacement line of carriers P and P', arranged in correspondence of both rotating supports TR and TR' and in correspondence of the position taken up by the operating reel, a motor-driven roll 6 is arranged. Said roll, together with its driving motor 6a, is mounted on a support arm 7, in turn swinging about a fixed vertical pin 8.
An actuation piston 9 is capable of controlling - through a motion transmission known per se - the oscillation of arm 7 about the vertical axis of pin 8. Motor-driven roll 6 can thereby be caused to oscillate between a home position (shown by continuous lines in fig. 2) and a work position (shown by discontinuous lines), wherein it is in contact with the peripheral surface of reel B1, for the function better described in the following.
Preferably, motor-driven roll 6 - having its rotating axis vertically oriented - is of a height equivalent to the height of the shortest reel to be used in the machine and it is coated with high-friction material, for example elastomeric material or rubber. The motor-driven, rubber roll 6, thus shaped, is hence highly effective both in maintaining the terminal edge of the film adherent to the reel - without letting it slip downwards under its own weight - and in assisting the rotation of the reel when necessary, so as to reduce traction stress during the operation.
When gripper S moves towards the centre Y-Y of the packaging station with a certain acceleration, it draws film 5 which, under this drawing action, tends to impart a significant traction on dancer roll 3, since the unwinding from reel B1 has a delayed reaction. Dancer roll 3 hence moves from a home position 3 to a loaded position, according to the elastic reaction of the tensioning spring acting on rocker arm 4.
The force of this tensioning spring is such that, whatever the position of dancer roll 3, ranging between the limit positions of the oscillation thereof about rotation centre 1 (position 3, home position, and position 3' in maximum tension conditions), film 5 is kept tensioned with a force sufficient to prevent an accidental downward slipping thereof. This is a fundamental condition - as stated also in the preliminary remarks - to always guarantee a correct packaging operation.
The operation of the described apparatus is the following: in non-operating conditions, all reels B1 to B5 are kept blocked on their respective spindles - i.e. in conditions not allowing unwinding of reel 5 - by disengageable braking means (not shown here). In this blocked position, gripper S - one for each reel, as shown in above-cited patent IT 1,356,529 - is temporarily fastened on the end of arm 2' while roll 3 is in its initial position (shown in fig. 2): film 5 then forms a double loop, running from the exit of reel B1, to stationary roll 3a, then to dancer roll 3 and finally to gripper S.
When a reel is brought into working position - in the case shown in the drawings, reel B1 - firstly piston 9 is activated, which brings motor-driven roll 6 in close contact with the peripheral surface of reel B1. Immediately afterwards said reel-braking means are deactivated and the drawing step of film 5 is started with the displacement of gripper S to the centre of transport line Y-Y.
During the entire drawing phase of film 5, motor-driven roll 6 is actuated - in a clockwise direction, to control the rotation of the reel in an anticlockwise direction - so as to cause reel B1 to rotate, always acting on the periphery thereof, i.e. where the peripheral velocity of the reel equals the unwinding velocity of film 5 in correspondence of gripper S.
In other words, the control of motor-driven roll 6 acts directly on the actual velocity of film supply, which would not be possible if one acted on a motorisation integral with the spindle of reel B1. The control of motor-driven roll 6 is proportional to the tension detected in film 5, so as to accelerate the rotation of the reel if the tension in the film increases excessively and, vice versa, reducing the unwinding velocity when the tension drops below the preset levels.
In such respect, the tension level in film 5 is detected by means of the same dancer roll 3, the oscillation of which is opposed by spring means. As a matter of fact, since it is elastic oscillation, by definition the displacement of the dancer roll is directly proportional to the force (= tension) applied on roll 3 by film 5.
Therefore, when arm 4 reaches a position corresponding to a preset tension T' of the film, motor-driven roll 6 is correspondingly driven with a certain rotation velocity, to impart an unwinding force peripherally to reel B1.
Preferably, in order to simplify the control mode, rubber roll 6 is caused to rotate always at the same velocity and with the same torque and the supply control is achieved by moving roll 6 closer to/away from the reel B1 by means of a driven piston 9, resulting in a change of applied pressure of roll 6 on reel B1. That is, when dancer roll 3 exceeds threshold positions of admissible minimum tension and of admissible maximum tension, motor-driven roll 6 is detached or urged against the reel periphery, respectively, by means of piston 9.
Therefore, the maintenance of the desired tension T' is accomplished with an intermittent angular actuation of motor-driven roll 6, corresponding to an oscillation of dancer roll 3 between a minimum and a maximum oscillation position.
This operation mode runs for the entire time in which the packaging on load C is performed with the film coming from reel B1.
When, at the end of one or multiple work cycles with reel B1, reel replacement is required - because the incoming load C is of a size not fitting to the height of the film of reel B1 - gripper S is brought back onto the support 2' thereof and the exceeding film is rewound at the same time.
In this step, the motorisation spindle of reel B1 is caused to rotate backwards, i.e. in a clockwise direction, to rewind the film on reel B1. In order to prevent the film from becoming excessively loose and tending to slip downwards, the same needs to be rewound on the reel with a certain degree of tensioning. For such purpose, in a fully similar way to the previous step, motor-driven roll 6 is caused to rotate in the same direction as before and urge intermittently on the film at the reel periphery, to keep the film at another, predetermined tension T", generally lower than tension T', but in any case sufficient to ensure a rewinding of the film without accidental downward slipping.
Once the rewinding has completed, gripper S has been blocked on its support 2', and reel B1 has been braked again, it is then possible to drive the rotation of rotating support TR to bring a new reel B2, B3, B4 or B5 in correspondence of line X-X of packaging station.
It is understood that the invention must not be considered limited to the particular arrangement illustrated above, which represents only an exemplifying embodiment thereof, but that a number of variants are possible, all within the reach of a person skilled in the field, without departing from the scope of protection of the invention, as defined by the following claims.

Claims

Vertical winding apparatus for the packaging of pallet loads progressing sequentially along a transport path (Y-Y), to a packaging station (X-X) arranged transversally to said transport path (Y-Y), of the type comprising two carts (TR, TR') for supporting a respective group of vertical-axis reels (B1 .. Bn; B1' .. Bn') of plastic film (5) of different quality/heights, said carts (TR, TR') being arranged at the two sides of the transport path (Y-Y) and being apt to carry a pair of reels of equal quality/height (B1, B1' ; . . . ; Bn, Bn'), according to choice, in correspondence of said packaging station (X-X), as well as a pair of carrying means (P) arranged in said packaging station (X-X) and each one moving from a position next to one of said support carts (TR, TR') to a central welding position and vice versa, each one of said carrying means (P) being apt to accompany in said movement one edge of the film (5) of said pair of reels (B1, B1' ; . . . ; Bn, Bn'), characterised in that it furthermore comprises, associated with each reel:
- a gripper (S) for the drawing of said edge of the film (5) carried by the reel (B1, B1' ; . . . ; Bn, Bn'), said gripper (S) being capable of being connected to and released from said carrying means (P),

- guiding and detecting means (3, 3a, 4, 6) of said film (5), comprising at least one dancer roll means (3) moving under the action of the tension in said film (5) against the action of elastic means, and

- a tensioning assembly (6, 7, 8, 9) comprising a roll driven in rotation acting on the periphery of said reel (B1, B1' ; . . . ; Bn, Bn'), the action of which can be modulated and controlled according to the position taken up by said dancer roll (3).
Apparatus as claimed in claim 1, wherein said guiding and detecting means comprise a rocker arm (4), carrying at the free end thereof a dancer roll (3) acting as deflector means of the film (5), said arm (4) oscillating under the thrust, on one side, of a tensioning spring and, on the other side, of the traction of the film (5) which unwinds or winds back up on the reel (B1, B1' ; . . . ; Bn, Bn').
Apparatus as claimed in claim 2, characterised in that said dancer roll (3) can take up two extreme positions, the exceeding of which produces a control signal for said tensioning assembly (6, 7, 8, 9).
Apparatus as claimed in claim 1, 2 or 3, characterised in that the deflection path of said film (5) on said dancer roll (3) comprises at least a first portion, between reel (B) and roll (3), and at least a second portion, between roll (3) and said gripper (S), said two portions forming a flattened-S-shaped path.
Apparatus as claimed in claim 4, characterised in that the deflection path of said film (5) on said dancer roll (3) comprises at least a third portion, between the exit from the reel (B1, B1' ; . . . ; Bn, Bn') and a stationary deflector roll (3a), which precedes the portion towards the dancer roll (3) in the progression direction of the film (5) to the load to be packaged.
Apparatus as claimed in any one of the preceding claims, characterised in that said roll driven in rotation (6) is mounted swinging between a position away from the reel (B1, B1' ; . . . ; Bn, Bn') and a position in in friction contact against the peripheral surface of the reel.
Apparatus as claimed in claim 6, characterised in that said roll driven in rotation (6) is mounted on a rocker arm (7) so as to be brought in contact with the peripheral surface of the reel (B1, B1' ; . . . ; Bn, Bn'), when it is necessary to reduce film tension, or to be moved away from said reel surface (B1, B1' ; . . . ; Bn, Bn'), respectively, when it is necessary to increase film tension.
Apparatus as claimed in any one of the preceding claims, characterised in that said tensioning assembly (6, 7, 8, 9) is operative in an equivalent manner both in a first rotation direction of the reel (B1, B1' ; . . . ; Bn, Bn'), during film supply, and in a second, opposite direction, during the rewinding of the reel (B1, B1' ; . . . ; Bn, Bn').