CN212922305U

CN212922305U - Labeling unit and automatic adjusting system for labeling unit

Info

Publication number: CN212922305U
Application number: CN202020258235.1U
Authority: CN
Inventors: 安妮-菲利普·拉丰
Original assignee: Sidel SpA
Current assignee: Sidel SpA
Priority date: 2019-03-08
Filing date: 2020-03-05
Publication date: 2021-04-09
Anticipated expiration: 2030-03-05
Also published as: DE202020101140U1

Abstract

The utility model relates to a labeling unit, which comprises a supporting structure; a conveyor movably carried by the support structure and feeding the labels to the application station; at least one position sensor carried by the support structure and sequentially detecting a position of each label applied to the associated item by the conveyor and generating a first data point associated with the detected position; and a control unit that receives the first data point and sequentially compares the first data point to a second data point associated with a predetermined nominal position of the tag on the associated article, and calculates an error in the detected position from the nominal position based on the comparison of the first data point and the second data point, wherein the unit further comprises an adjustment assembly carried by the support structure and controlling the conveyor to move relative to the support structure, and wherein the control unit further controls the adjustment assembly to cause the conveyor to move when the position error is not zero. It also relates to an automatic adjustment system for the labelling unit.

Description

Labeling unit and automatic adjusting system for labeling unit

Technical Field

The present invention relates to a labelling unit designed to handle labelling materials in an automatic labelling process, in particular a labelling unit designed to apply a label obtained from a strip of labelling material to an article, in particular an article designed to contain a pourable product (preferably a food product).

Background

Labelling units designed to handle labelling materials in an automatic labelling process are known and are generally used for preparing, transporting and applying labels onto articles (in particular bottles, containers, etc.) designed to be filled with pourable products, preferably pourable food products.

It is common to use "adhesive labels" obtained from a strip of labelling material wound on one or more reels.

In particular, such a strip is cut into equally sized portions and glue is applied to said portions. The glue is applied using an adhesive device such as a roller, spray system, injection system, etc. The labels thus obtained are then transferred and glued to the outer side of the respective article.

Another type of labelling, which is particularly common, involves the production of tubular labels, called "sleeve labels", from a ribbon-like heat-shrinkable film wound on one or more reels, which have a certain degree of play around the respective article, and are then heated in a kiln, causing the film to shrink and adhere completely to the sides of the article. This type of label does not require gluing.

Another type of labelling, known as "PSL", involves making self-adhesive labels, which are initially arranged on a support tape, detaching the labels from the support tape and then applying the labels directly to the respective articles.

In particular, the label is separated from the support tape by passing the support tape over a deflector which forces the support tape into a very tight and narrow angle and then is applied directly to the article.

Whatever the label used, the labelling unit generally comprises:

a carousel rotating about a vertical axis and designed to convey a plurality of successive articles along a horizontal semicircular path,

an input station where the articles to be labelled are fed onto the carrousel,

-an output station where the labelled articles leave the turntable, and

-one or more labelling modules arranged around the periphery of the carrousel and designed to feed a respective plurality of labels to the carrousel at an application station in order to apply said labels onto respective articles.

The labelling module generally comprises:

one or more storage units, generally rollers, on which respective reels of labelling material are wound in the form of a continuous strip,

-a plurality of unwinding rollers (unwinding rollers) which, in use, support unwinding of the strip from the reel and guide the strip along a feed path, and

-a label transfer device designed to receive each label and to feed it onto the carrousel at an application station.

In the case of "adhesive labels" and "sleeve labels", the labelling modules also comprise a blade designed to cut a series of single labels of the same length from the strip of labelling material at a cutting station.

Furthermore, in the case of labels that need to be glued, the labelling module also comprises at least one gluing roller designed to coat at least one end of each label with glue.

The "sleeve" label is folded into a tube around a respective forming mandrel presented by a rotating disc, wherein the article to be labelled is carried on top of said mandrel, then the label is glued with both ends overlapped, at which point the mandrel is withdrawn towards the bottom of the rotating disc to enable the article to be inserted with clearance into the respective tubular label, and then the article with the "loose" label is transferred into a heating kiln to heat-shrink the label and completely adhere it to the article.

In the case of PSL labels, the conveying device is the above-mentioned deflector plate which deflects the support tape at a very tight and narrow angle in order to sequentially separate the labels from the support tape and to direct each label towards the corresponding article, so as to deliver the label at the correct inclination. This ensures that the label is applied to the article at a predetermined nominal angle, which determines the nominal application or positioning of the label on the article.

Advantageously, the turntable, the conveying device, the gluing roller and the unwinding roller are synchronized in phase so as to correctly perform the entire labelling process.

In the above-mentioned labelling machine field, it is known that one or more labels are not applied correctly (i.e. nominally) to the relative article.

More specifically, a label is considered to be properly or nominally positioned on an article if it occupies a predetermined nominal application area on a side of the article.

If the tag is outside the predetermined nominal zone, the tag is considered to be non-nominally located.

This results in the article being discarded if the label is not nominally applied, thereby wasting the article and labeling material.

Furthermore, after a predetermined number of discarded articles has been reached (for example five), the machine is stopped to prevent excessive waste of labelling material and articles, and one or more labelling modules are manually adjusted.

In particular, each labelling module comprises one or more adjustment shafts, each generally having:

a worm member, usually a screw, fastened to the static support structure and anchored to the support floor, and

a female threaded member, typically an internally threaded sleeve, which is movably coupled to the worm member and kinematically connected to the transmission means.

More specifically, the female threaded member is rigidly connected to the base of the labelling module supported by the support structure, which is in turn kinematically or rigidly connected to the conveyor, so that the above-mentioned adjustment shaft can be used to adjust the position of the base, causing a corresponding movement and a corresponding adjustment of the conveyor.

This makes it possible to adjust or vary the positioning, i.e. the inclination and/or distance with respect to the article, and thus its final position with respect to the predetermined nominal area, at the application station for applying the label to said article.

As described above, this adjustment is performed manually by the operator after the machine is stopped.

The applicant has observed that a labelling unit arranged in the above-described manner, although operationally effective, can be improved.

In particular, there is a clear need in the field to minimize the downtime of the labelling unit in order to maximize its productivity.

SUMMERY OF THE UTILITY MODEL

The object of the present invention is to obtain a highly reliable, low-cost labelling unit that can satisfy the above-mentioned requirements relating to known labelling units.

According to the utility model discloses, this purpose is realized through pasting the mark unit. A labelling unit designed to apply a label obtained from a strip of labelling material to an article, said unit comprising: a support structure; a conveyor movably carried by the support structure and designed to receive a series of said labels one after the other and to feed them to an application station where they are applied to respective articles; at least one position sensor carried by the support structure and designed to sequentially detect the position of each label applied to the relative item by the conveyor and to generate a first data point correlated to the detected position; and a control unit designed to receive said first data point and to sequentially compare said first data point with a second data point relating to a predetermined nominal position of said label on the relative article, and to calculate a position error between said detected position and said nominal position on the basis of the comparison between said first and second data points, wherein said unit further comprises an adjustment assembly carried by said support structure, kinematically connected to said conveying device, and designed to control said conveying device in motion with respect to said support structure, and wherein said control unit is further designed to control said adjustment assembly so as to cause said movement of said conveying device when said position error calculated for a predetermined number of labels is not zero.

Drawings

Three non-limiting preferred embodiments are described below, by way of example only, and with reference to the accompanying drawings, in which:

figure 1 is a schematic top view of a labelling unit according to a first embodiment of the present invention, with parts removed for clarity,

figures 2 and 3 are schematic enlarged perspective views of the details of the labelling unit in figure 1 in different operating conditions, with parts removed for clarity,

figure 4 is a schematic top view of a labelling unit according to a second embodiment of the invention, with parts removed for clarity, an

Figure 5 is a schematic top view of a labelling unit according to a third embodiment of the present invention, with some parts removed for the sake of clarity.

Detailed Description

In fig. 1, reference numeral 1 is used to indicate the whole labelling unit, which is designed to handle labelling material in an automatic labelling process.

In particular, unit 1 is part of a packaging line for pourable products and is designed to apply labels 2 obtained from a strip 3 of labelling material to articles 4, in particular articles 4 designed to contain pourable products, preferably food products.

In the example shown in figures 1, 2 and 3, the label 2 applied by the machine 1 is a known "PSL" label, i.e. a self-adhesive label 2, which is initially arranged on the support tape 3a, is separated (removed) from the support tape 3a and is then applied directly to the respective article 4.

The band of labelling material 3 thus comprises a support tape 3a and a label 2 initially attached to the support tape 3 a.

The unit 1 basically comprises:

a static support structure 12 anchored to a supporting floor (not shown),

a carousel 5 rotating about a vertical axis Z, said carousel 5 being carried by a support structure 12, in particular by the support structure 12, and being designed to convey a plurality of successive articles 4 along a horizontal semicircular path P,

an input station I via which the items 4 are fed to the carousel 5,

an output station O, which receives labelled articles 4 from carousel 5.

An output conveyor, for example an output star-wheel 6, designed to receive the labelled articles 4 from the carousel 5 at an output station O and to move them to an end conveyor (not shown), and

at least one labelling module 7, said labelling module 7 being carried by a support structure 12, in particular by the support structure 12, arranged around the periphery of the carrousel 5 and designed to feed a plurality of labels 2 to the carrousel 5 in order to apply them to respective articles 4 at the application station a.

Specifically, labelling module 7 comprises:

a base 13, said base 13 being movably carried by the support structure 12, in particular being movably supported by the support structure 12,

at least one shaft 8, said shaft 8 being fastened to a base 13 and being designed to rotatably support at least one reel 9, from which reel 9 the strip 3 of labelling material is unwound,

a plurality of unwinding rollers 10, said unwinding rollers 10 being rotatably fastened to a base 13 and supporting, in use, unwinding of the strip 3 from the reel 9 and guiding it along a feed path; and

a conveyor 11, said conveyor 11 being mounted on a base 13 and being designed to receive the labels 2 and to feed (convey) them to the respective articles 4 at an application station a.

According to this preferred embodiment, the conveying means are formed by a deflector plate 14, said deflector plate 14 being mounted on the base 13, in particular being rigidly connected to the base 13.

In particular, the deflector plate 14 is designed to interact with the strip of labelling material 3 in a known manner not described in detail, so as to force the support belt 3a into a very tight and narrow curvature. This deflection causes the self-adhesive labels 2 to be separated from the support tape 3a and to be applied directly to the articles 4 at the application station a.

In other words, in use, the deflector plate 14 causes the sequential separation of the labels 2 from the supporting tape 3a and guides each label 2 towards the relative article 4, so as to deliver the label 2 in the desired positioning, in particular at the desired inclination.

This ensures that each label 2 is applied to the associated article 4 at a predetermined nominal angle, which results in a nominal application or positioning of the label 2 on the article 4.

More specifically, each label 2 is designed to be applied, in use, to a predetermined nominal application area 40, said predetermined nominal application area 40 defining a portion, in particular a substantially cylindrical portion, of the outer surface of the relative article 4.

The unit 1 also comprises a position sensor 15, said position sensor 15 being carried by the supporting structure 12, in particular being supported by the supporting structure 12, more particularly being fastened to the supporting structure 12, and being designed to sequentially detect the position of each label 2 applied to the relative item 4 by the conveyor 11.

The position sensor 15 is further designed to generate a first data point, for example a position signal, which is related to the detected position.

Preferably, the position sensor 15 is a photocell or other equivalent observation and detection system arranged around the periphery of the carousel 5, said carousel 5 being downstream of the application station a and upstream of the output station O, in order to detect the position of the label 2 that has been applied to the relative article 4.

According to an alternative embodiment (not shown), the position sensor 15 is arranged downstream of the output station O. In the latter case, the position sensor 15 is arranged on the periphery of the output star 6.

The unit 1 further comprises a control unit 16, said control unit 16 being designed to receive the above-mentioned first data point generated by the position sensor 15 and to sequentially compare the first data point with a second data point relating to a predetermined nominal position (for example a predetermined nominal position) of the tag 2 on the relative item 4, and to calculate a position error between the detected position and the nominal position on the basis of the comparison between the first data point and the second data point.

More specifically, the position sensor 15 is designed to sequentially detect the position of each label 2 with respect to the above-mentioned relative predetermined nominal application zone 40 of each article 4.

The control unit 16 is therefore designed to make a comparison between the detected position of the label 2 or the area of the outer surface of the article 4 actually occupied by the label 2 and the nominal application area 40 of the article 4 concerned.

In other words, the control unit 16 is designed to calculate a possible positioning error of the label 2 with respect to the corresponding nominal application area 40 by comparing the first data point and the second data point.

Preferably, the positioning error is defined, in use, by the misalignment or non-nominal inclination of the label 2 with respect to the nominal application area 40.

In a preferred embodiment, the non-nominal positioning of the label 2 may be defined as an imperfect overlap of the label 2 over the corresponding nominal application area 40, caused by other unspecified non-nominal operating conditions. In the latter case, the position sensor 15 detects the current position (wrong, non-nominal position) of the tag 2 and the control unit 16 calculates a non-zero position error.

As shown in fig. 1, 2 and 3, the unit 1 further comprises an adjustment assembly 17, said adjustment assembly 17 being carried by the support structure 12, in particular being supported by the support structure 12, being kinematically connected to the deflector plate 14 and designed to control the movement of the deflector plate 14 with respect to the support structure 12 between a nominal operating position and an adjusted operating position.

In particular, the adjustment assembly 17 comprises a plurality of adjustment shafts 18.

Hereinafter, for the sake of brevity, the description refers to a single adjustment shaft 18.

In particular, the description hereafter refers to the adjustment shaft 18, said adjustment shaft 18 controlling the vertical movement of the base 13 and, consequently, of the deflector plate 14 (fig. 2 and 3).

However, the features described and illustrated below for the adjustment shaft 18 apply to each adjustment shaft 18 of the adjustment assembly 17.

More specifically, the adjustment shaft 18 includes:

a worm member, in particular a screw 19, carried by the support structure 12, in particular fastened to the support structure 12, and

a female threaded member, in particular a threaded sleeve 20, which is movably coupled to the screw 19 and kinematically connected to the deflector plate 14.

More specifically, the threaded sleeve 20 is coupled to the base 13 such that movement of the threaded sleeve 20 along the threaded rod 19 corresponds to movement of the base 13.

Preferably, the threaded sleeve 20 is rigidly connected to the base 13, in this case by means of bolts, so that the movement of the threaded sleeve 20 along the threaded rod 19 corresponds to the movement of the deflector plate 14 rigidly connected to the base 13 as described above.

The base 13 is therefore designed to transmit the movement of the threaded sleeve 20 to the deflector plate 14.

According to the invention, the control unit 16 is also designed to control the adjustment shaft 18 when, for a predetermined number of labels, the position error calculated on the basis of the first and second data points is not zero, in order to move the deflector plate 14 between the nominal operating position and the operating position of its adjustment.

In particular, the control unit 16 is designed to control the adjustment axis 18 so as to gradually reduce the position error as long as said error is not zero.

In order to automatically move the deflection plate 14, the adjustment shaft 18 has an actuator, preferably an electric motor 21, more preferably a stepper motor, which is operatively coupled to the screw 19 and is designed to automatically control the rotation of the screw 19.

In use and according to the known screw/female thread coupling, rotation of the screw 19 causes movement of the screw sleeve 20 relative to (along) the screw 19 and thus of the base 13 and deflector plate 14 relative to the support structure 12.

More specifically, the control unit 16 is designed to actuate the electric motor 21 on the basis of a comparison between the first and second data points, i.e. as long as the position error is not zero.

In other words, if the position sensor 15 detects that a given number of tags 2 (for example one tag 2 or more than one, in particular more than five tags 2) are positioned non-nominally, the control unit 16 controls the actuation of the electric motor 21, which causes the screw 19 to rotate, which in turn causes the screw sleeve 20 to move along the screw 19.

This movement in turn causes the base 13 and therefore the deflector plate 14 to move from the nominal operating position to the adjusted operating position.

More specifically, the adjusted operating position refers to the position of the deflector plate 14, at which the label 2 is again nominally applied to the article 4 (i.e. nominal position) after adjustment based on the above-mentioned detection by the position sensor 15 and on the above-mentioned control by the control unit 16.

According to this preferred non-limiting embodiment, the adjustment assembly 17 has four adjustment shafts 18, each designed to control:

the base 13 and therefore the vertical movement of the deflector plate 14 with respect to the support structure 12,

the base 13 and therefore the horizontal movement of the deflector plate 14 with respect to the support structure 12,

the base 13 and thus the pitch or vertical tilt movement of the deflector plate 14 relative to the support structure 12,

the base 13 and therefore the rolling or lateral tilting movement of the deflector plate 14 with respect to the support structure 12.

Furthermore, the adjustment assembly 17 can control any combination of the aforementioned movements.

In view of the foregoing, the adjustment assembly 17, and therefore all the adjustment shafts 18 with the associated screw 19, the associated threaded sleeve 20 and the associated electric motor 21, the position sensor 15 and the control unit 16 are part of an adjustment system 50, said adjustment system 50 being designed to adjust the position of the conveyor 11 or the deflection plate 14 of the labelling module 7.

The operation of the unit 1 according to the invention is described below with particular reference to an initial condition in which the label 2 is applied non-nominally to the article of interest 4.

In this state, once the item 4 reaches the position sensor 15, said sensor detects the position of the tag 2 and generates a respective first data point associated with the respective detected position, which is then sent to the control unit 16.

At this point, the control unit 16 compares each first data point with a second data point associated with a predetermined nominal position and calculates a position error.

If the calculated position error is not zero, the control unit 16 controls the respective electric motor 21 that actuates the adjustment shaft 18 in order to change the position of the base 13 and thus adjust the position of the deflector plate 14.

As long as the positioning error is not zero, the adjustment continues so as to gradually adjust the position of the label 2 on the article 4 until the predetermined nominal position is reached again.

In fig. 4, reference numeral 1' is used to indicate a labelling unit according to a second embodiment of the present invention.

Since unit 1' is similar in structure and operation to unit 1, the following description lists only the differences between the two by using the same reference numerals to designate equivalent or similar features.

In particular, unit 1 ' differs from unit 1 in that the label 2 ' handled by unit 1 ' is a "glue label", i.e. a portion of labelling material of predetermined length cut from the strip 3 of labelling material wound on one or more reels 9 using a blade 22 and coated with glue. These labels 2' are conveyed one after the other and applied to the outer surface of the respective article 4.

Furthermore, unit 1 'comprises a labelling module 7', said labelling module 7 'comprising a conveyor 11' formed by a vacuum drum 14 ', known and not described in detail, said vacuum drum 14' being mounted on a base 13 rotating about itself and being designed to receive and move each label 2 'previously cut from strip 3 and to apply said label 2' to a respective article 4 at an application station a.

According to this second preferred embodiment, the adjustment shaft 18 is designed to control the movement of the vacuum drum 14' between the nominal operating position and the adjusted operating position.

This operation is similar to that described above for unit 1.

In fig. 5, reference numeral 1' is used to indicate a labelling unit according to a third embodiment of the present invention.

In particular, unit 1 "differs from unit 1 in that unit 1" processes labels 2 "of known type, called" sleeve labels ", i.e. tubular labels 2" made of a strip of heat-shrinkable film wound on one or more reels 9, these tubular labels 2 "having a certain degree of play around respective articles 4 and then being heated in a kiln so that the film shrinks and adheres completely to the sides of articles 4. In this case, no glue is required.

To this end, unit 1 "comprises a labelling module 7", said labelling module 7 "comprising a conveyor 11" formed by a vacuum drum 14 ", said vacuum drum 14" being similar to vacuum drum 14 'of conveyor 11' and being designed to process "sleeve" labels 2 ".

This operation is similar to that described above for cell 1'.

An examination of the characteristics of the

unit

1, 1', 1 "made according to the present invention clearly reveals the advantages that can be obtained.

In particular, the adjustment shaft 18, the detection performed by the position sensor 15 and the control by the control unit 16 can be used to automatically adjust the

conveyors

11, 11 ', 11 "so that frequent stops of the unit 1 are no longer required when the control unit 16 calculates a non-zero position error for one or

more labels

2, 2', 2".

This may reduce or eliminate machine downtime required to make the necessary adjustments.

This makes the labelling process more efficient, fast and linear.

It is clear that modifications and variations can be made to the

unit

1, 1', 1 "described and illustrated herein without thereby departing from the scope of protection defined by the claims.

In particular, the actuator 21 of the adjustment shaft 18 may be a pneumatic, hydrodynamic or electromagnetic actuator.

Furthermore,

unit

1, 1 ', 1 "may comprise all the different types of

labelling modules

7, 7', 7" simultaneously or a combination thereof.

Furthermore, the adjustment effected by the adjustment shaft 18 can be used for the purpose of a program change at the end of each labeling process. Thus, by presetting in the control unit 16 position values corresponding to the specifications of the new program, the adjustment assembly 17 can automatically adjust the positions of the different components without any manual intervention by the operator.

In addition, the adjustment system 50 shown and described herein and applied to unit 1 can be implemented in other units or machines installed along the pourable product packaging line.

For this purpose, the adjustment system 50 may be designed to automatically adjust the position of the base of such a unit or machine, for example the base of a blower or the base of a kiln of a blower. In this case, the position sensor 15 of such an adjustment system 50 would be designed to sequentially detect the position of at least one distinct element, such as a reference strip or notch, arranged on the outer surface of each article 4.

Claims

1. Labelling unit designed to apply labels (2, 2') obtained from a strip (3) of labelling material onto articles (4), characterised in that it comprises:

-a support structure (12),

-conveying means (11, 11 ') movably carried by said supporting structure (12) and designed to receive a succession of said labels (2, 2') one after the other and to feed said labels (2, 2 ') to an application station (A) where said labels (2, 2') are applied to respective articles (4),

-at least one position sensor (15) carried by said support structure (12) and designed to sequentially detect the position of each label (2, 2 ') applied to the relative item (4) by said conveying means (11, 11') and to generate a first data point correlated to the detected position, and

-a control unit (16) designed to receive said first data point and to sequentially compare said first data point with a second data point relating to a predetermined nominal position of said label (2, 2') on the item of interest (4), and to calculate a position error between said detected position and said nominal position based on the comparison between said first and second data points,

wherein the labelling unit further comprises an adjustment assembly (17), the adjustment assembly (17) being carried by the support structure (12), being kinematically connected to the conveying means (11, 11 ', 11 ") and being designed to control the movement of the conveying means (11, 11', 11") with respect to the support structure (12),

and wherein said control unit (16) is further designed to control said adjustment assembly (17) so as to cause said movement of said conveyor (11, 11 ', 11 ") when said position error calculated for a predetermined number of labels (2, 2', 2") is not zero.

2. Labelling unit according to claim 1, characterised in that the control unit (16) is designed to control the adjustment assembly (17) so as to gradually reduce the position error as long as it is not zero.

3. Labelling unit according to claim 1 or 2, characterised in that said adjustment assembly comprises an actuator (21), said actuator (21) being designed to automatically control the movement of the conveying means (11, 11', 11 ");

the control unit (16) is designed to actuate the actuator (21) based on a comparison between the first data point and the second data point.

4. Labelling unit according to claim 3, characterised in that said adjustment assembly (17) comprises: a worm member (19) carried on the support structure (12); and a female threaded member (20) movably coupled to the worm member (19) and kinematically connected to the transfer means (11, 11'),

the actuator (21) is operatively connected to the worm member (19) and is designed to actuate the worm member (19) so as to move the female threaded member (20) with respect to the worm member (19).

5. Labelling unit according to claim 4, characterised in that it further comprises a base (13), said base (13) being movably carried by said support structure (12) and coupled to said female threaded member (20),

said conveying means (11, 11') being mounted on a base (13),

the base (13) is designed to transmit the movement of the female threaded member (20) to the transfer means (11, 11', 11 ").

6. Labelling unit according to claim 5, characterised in that said conveying means (11, 11', 11 ") comprise a deflector plate (14) rigidly connected to said base (13).

7. Labelling unit according to claim 5, characterised in that said conveying means (11, 11 ', 11 ") comprise a vacuum drum (14', 14") rotatably mounted on said base (13) around itself.

8. Labelling unit according to claim 1 or 2, characterised in that said adjustment assembly (17) is designed to control:

-vertical movement of the transfer device (11, 11') with respect to the support structure (12), and/or

-horizontal movement of the transfer device (11, 11') with respect to the support structure (12), and/or

-a pitching movement of the transfer device (11, 11', 11 ") with respect to the support structure (12), and/or

-a rolling movement of the transfer device (11, 11', 11 ") with respect to the support structure (12), and/or

-a combination of the above movements.

9. Labelling unit according to claim 8, characterised in that it comprises at least one adjustment assembly (17) for each of the vertical, horizontal, pitch and roll movements of the conveying device (11, 11', 11 ") with respect to the support structure (12).

10. Labelling unit according to claim 1 or 2, characterised in that said position sensor (15) is designed to sequentially detect the position of each label (2, 2', 2 ") with respect to an associated predetermined nominal application area of each article (4).

11. Labelling unit according to claim 1 or 2, characterised in that said position sensor (15) is arranged downstream of said application station (a).

12. Labelling unit according to claim 11, characterised in that it further comprises a conveyor (5) designed to move a plurality of said articles (4) along a conveying path (P) from an input station (I) to an output station (O),

wherein the position sensor (15) is arranged downstream of the output station (O).

13. Labelling unit according to claim 12, characterised in that said position sensor (15) is arranged downstream of said application station (a) and upstream of said output station (O).

14. Automatic adjustment system for labelling units, said labelling units (1) being intended to handle articles (4) on a packaging line of pourable products, characterised in that it is designed to adjust the position of a base (13) of said labelling unit and comprises:

-at least one position sensor (15) designed to sequentially detect the position of at least one unique element on each item (4) and to generate first data points relating to the detected positions,

-a control unit (16) designed to receive said first data point and to sequentially compare said first data point with a second data point relating to a predetermined nominal position of said unique element on the item of interest (4), and to calculate a position error between said detected position and said nominal position on the basis of the comparison between said first and second data points; and

-an adjustment assembly (17) kinematically connected to the base (13) and designed to control the movement of the base (13),

wherein the control unit (16) is further designed to control the adjustment assembly (17) so as to cause the movement of the base (13) when the position error calculated for a predetermined number of unique elements is not zero.

15. Automatic adjustment system for labelling units according to claim 14, characterised in that said control unit (16) is designed to control said adjustment assembly (17) as long as said position error is not zero, so as to gradually reduce said position error, so as to control said movement of said base (13) as long as said position error is not zero.