TECHNICAL FIELD

The present invention relates to a labeling machine for applying label sheets onto receptacles. In particular, the present invention relates to a labeling machine for applying sleeved label sheets onto receptacles.

The present invention also relates to a labeling method for applying label sheets onto receptacles, in particular to apply sleeved label sheets onto receptacles.

BACKGROUND ART

Different techniques are known on how to apply label sheets on receptacles such as bottles, cans, and the like.

One of these techniques relies on the formation of sleeved label sheets, which are of a heat-shrink labeling material, to superimpose the sleeved label sheets onto respective receptacles and to perform a heat-shrinking action on the sleeved label sheets so that these adhere to the respective receptacles so as to remain attached to the respective receptacles.

The application of the sleeved label sheets is done with automated labeling machines.

A typical labeling machine for the application of sleeved label sheets comprises:

- a conveyor device, typically of the rotary type, for advancing the sleeved label sheets, each having a respective seam portion along a label advancement path and for advancing receptacles along a receptacle advancement path; and

- a welding apparatus for welding the sleeved label sheets along the respective seam portion during advancement of the sleeved label sheets along a welding portion of the label advancement path.

In more detail, the conveyor device comprises a plurality of treatment units, each one adapted to receive at least one respective single label sheet at a supply station, to form the respective sleeved label sheet through overlapping of the respective lateral edges of the respective single label sheet and to retain the respective sleeved label sheet along at least a portion of the label advancement path.

Each treatment unit is also adapted to receive one respective receptacle at the inlet station.

Typically, the labeling machine also comprises a label supply apparatus, arranged adjacent to the conveyor device, for supplying the single label sheets to the conveyor device at the supply station.

Furthermore, the labeling machine also comprises a heating unit, arranged adjacent to the conveyor device, for heating the sleeved label sheets, in particular when being superimposed on the respective receptacles, so as to execute a heat-shrinkage operation on the sleeved label sheets.

The labeling machine also comprises an inlet star wheel adapted to direct the receptacles to the inlet station and an outlet star wheel adapted to receive the receptacles, in particular the labeled receptacles, at the outlet station.

In more detail, each treatment unit comprises a mandrel being rotatable around a central axis and being adapted to receive one respective single label sheet at the supply station and to form the sleeved label sheet upon rotation of the mandrel around the central axis.

Each mandrel is provided with a plurality of suction holes along its outer lateral surface so as to selectively retain one single sleeved label sheet by means of suction on the outer lateral surface.

Each mandrel is also configured to rectilinearly move between an extended configuration and a retracted configuration so as to allow for the transfer of the sleeved label sheets from the mandrel onto the respective receptacle so that the respective sleeved label sheet at least partially superimposes the respective receptacle. For this reason, each mandrel is also configured to at least partially carry the respective receptacle, which moves between a first elevation level and a second elevation level upon movement of the respective mandrel between the extracted configuration and the retracted configuration .

Each treatment unit also comprises an auxiliary suction member so as to keep the respective sleeved label sheet in position, in particular during movement of the respective mandrel from the extracted configuration to the retracted configuration and prior to the activation of the heating unit.

In more detail, the welding apparatus comprises a plurality of welding heads coupled to the conveyor device and each one associated to one respective treatment unit and each one being adapted to weld the respective sleeved label sheet along the respective seam portion during advancement of the respective label sheet along the welding portion of the label advancement path.

As the modern labeling machines are equipped with a significant number of treatment units, each welding apparatus is required to have a significant number of welding heads. Indeed, the number of welding heads of the welding apparatus equals the number of treatment units.

As the costs of each welding head are high, the costs associated to the welding apparatus are high.

DISCLOSURE OF INVENTION

It is therefore an object of the present invention to provide a labeling machine to overcome, in a straightforward and low-cost manner, the aforementioned drawbacks .

It is therefore a further object of the present invention to provide a labeling method to overcome, in a straightforward and low-cost manner, the aforementioned drawbacks .

According to the present invention, there is provided a labeling machine as claimed in claim 1.

According to another aspect of the present invention, there is provided a labeling method as claimed in claim 10. Further preferred embodiments are claimed in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Figure 1 is a schematic top view of a labeling machine, with parts removed for clarity; and

Figure 2 is a side view of a detail of the labeling machine, with parts removed for clarity.

BEST MODES FOR CARRYING OUT THE INVENTION

Number 1 in Figure 1 illustrates as a whole a labeling machine for applying sleeved label sheets 2 onto receptacles, such as bottles 3, cans, containers, or the like.

In particular, the receptacles are adapted to be filled with a pourable product, in particular a pourable food product, such as carbonated liquids (e.g. sparkling water, soft drinks and beer) or non-carbonated liquids (e.g. still water, juices, teas, sport drinks, liquid cleaners, wine, emulsions, suspensions, high viscosity liquids and beverages containing pulps) .

In particular, the receptacles can be fed to labeling machine 1 prior to or after filling of the receptacles with the pourable product .

The following description will refer without any limitative scope to the receptacles being bottles 3 being made from a polymer such as polytetrafluoroethylene (PET) , glass, aluminum, steel or composites.

With reference to Figure 2, each bottle 3 extends along a longitudinal axis A, comprises a hollow main body 4 bounded by sidewalls 5, in particular substantially parallel to axis A, a bottom wall 6 substantially perpendicular to axis A and a top neck (not shown and known as such) substantially coaxial with axis A; in particular, the top neck delimits a pouring/inlet opening of bottle 3 opposite to bottom wall 6 allowing for filling bottle 3 with the pourable product and for pouring out the pourable product from bottle 3.

Labeling machine 1 is adapted to apply at least one sleeved label sheet 2 being of a heat-shrinkable material.

In particular, labeling machine 1 is adapted to apply at least one sleeved label sheet 2 onto at least a portion of the respective sidewalls 5 of the respective bottles 3.

In particular, each sleeved label sheet 2 has a substantially cylindrical configuration and extends along a longitudinal axis B (see Figure 2) .

Even more particular, each sleeved label sheet 2 is obtained from a single label sheet 7 extending along a longitudinal axis, defining longitudinal axis B, and a transversal axis.

Preferentially, each sleeved label sheet 7 is obtained by overlapping lateral edges 8, in particular lateral edges 8 being parallel to axis B (and the longitudinal axis of the respective label sheet) , so as to form a respective seam portion 9.

With particular reference to Figure 1, labeling machine 1 comprises a main conveyor device 10 configured to receive single label sheets 7 at a supply station 11, to form sleeved label sheets 2 from single label sheets 7 and to advance sleeved label sheets 2 along a label advancement path P, in particular label advancement path P being arc-shaped.

Preferentially, conveyor device 10 is also configured to advance bottles 3 from an inlet station 12 to an outlet station 13 along a receptacle advancement path Q, in particular receptacle advancement path Q being arc-shaped .

Advantageously, labeling machine 1 also comprises a welding apparatus 17 configured to weld, in particular thermally weld, even more particular to thermally weld by means of ultrasonic waves, each sleeved label sheet 2 along the respective longitudinal seam portion 9, during advancement of each sleeved label sheet 2 along at least a welding portion PI of label advancement path P, in particular welding portion PI being arc-shaped.

Preferentially, labeling machine 1 also comprises a label supply apparatus 18 (known as such and not further described) arranged adjacent to main conveyor device 10 at supply station 11 and being configured to supply single label sheets 7 to main conveyor device 10 at supply station 11.

Preferentially, labeling machine 1 also comprises a heating apparatus 19 (known as such and not further explained) adapted to heat sleeved label sheets 2, in particular when at least partially superimposing the respective bottles 3, so as to induce a heat-shrinkage of sleeved label sheets 2, so that each sleeved label sheet 2 remains attached to the respective bottles 3.

Preferably, labeling machine 1 also comprises an inlet conveyor, in particular an inlet star wheel 20, adapted to deliver bottles 3 to be labeled to inlet station 12 and an outlet conveyor, in particular an outlet star wheel 21, adapted to receive labeled bottles 3 and, in particular to direct labeled bottles 3 to heating apparatus 19, and in particular to further treatment machines .

With particular reference to Figures 1 and 2, main conveyor device 10 comprises a plurality of treatment units 22 each one adapted to receive at least one respective single label sheet 7 at supply station 11, to form the respective sleeved label sheet 2 through overlapping of the respective lateral edges 8 and to retain the respective sleeved label sheet 2 along at least a portion of label advancement path P and a conveyor structure 23, in particular a conveyor carousel rotatable around a respective rotation axis F, carrying treatment units 22 and being adapted to advance treatment units 22 along an endless path through supply station 11, inlet station 12 and outlet station 13. In particular, the endless path is circularly shaped.

In particular, treatment units 22 are equally spaced angularly around rotation axis F. In particular, each treatment unit 22 is also adapted to receive one respective bottle 3 at inlet station 12, to retain the respective bottle 3 during advancement of the respective bottle 3 along path Q and to release the respective bottle 3 at outlet station 13.

Preferentially, each treatment unit 22 is also configured to transfer each sleeved label sheet 2 onto the respective bottle 3, in particular while the respective sleeved label sheet 2, in use, advances along a transfer portion P2 of path P, downstream of welding portion PI along path P.

In more detail, each treatment unit 22 comprises a mandrel 24 being rotatable around a central axis G and being adapted to receive one respective single label sheet

7 at supply station 11, to form the respective sleeved label sheet 2 upon rotation around central axis G and to retain the respective sleeved label sheets 2 during advancement along at least a portion of label advancement path P. In particular, in use, one of the lateral edges

8 of the respective label sheet 7 is transferred to the respective mandrel 24 as a leading edge and the other one of the lateral edges 8 of the respective label sheet 7 is transferred to the respective mandrel 24 as a trailing edge. Even more particular, in use, upon rotation of the respective mandrel 24 and advancement of the respective treatment unit 22 (and the respective mandrel 24) along the endless path the lateral edge 8 being the trailing edge is superimposed on the lateral edge 8 being the leading edge.

Preferentially, each mandrel 24 is provided with a plurality of suction holes (not shown) along its outer lateral surface 25 so as to selectively retain the respective sleeved label sheet 2 by means of suction on the respective outer lateral surface 25.

Preferentially, each mandrel 22 is also configured to rectilinearly move between an extended configuration and a retracted configuration so as to allow for the transfer of the respective sleeved label sheet 2 onto the respective bottle 3 so that the respective sleeved label 2 at least partially superimposes the respective bottle 3. In particular, the movement between the extended configuration and the retracted configuration is actuated upon a linear movement of the respective mandrel 24.

In particular, each mandrel 22 is controlled into the extracted configuration at supply station 11 and is controlled into the retracted configuration, in use, after the welding of the respective sleeved label sheet 2 along the respective seam portion 9, in particular during advancement of the respective sleeved label sheet 2 along portion P2.

Preferably, each mandrel 22 is also configured to at least partially carry the respective bottle 3, in particular with axis A having a vertical orientation. In particular, with the respective mandrel 24 being in the extracted configuration and the retracted configuration the respective bottle 3 is arranged at respectively a first elevation level and at a second elevation level (the first elevation level being higher than the second elevation level) .

Each treatment unit 22 also comprises an auxiliary suction member (not shown) so as to keep the respective sleeved label sheet 2 in position, in particular during movement of the respective mandrel 24 from the extracted configuration to the retracted configuration, so as to allow for the transfer of the respective sleeved label sheet 2 onto the respective bottle 2. In particular, during the movement of the respective mandrel 24 from the extracted configuration to the retracted configuration also the respective bottle 3 is moved. Even more particular, as the respective sleeved label sheet 2 is, in use, held at place by the respective auxiliary suction member, the respective bottle 3 enters into the respective sleeved label sheet 2 having a substantially cylindrical shape .

With particular reference to Figure 1, welding apparatus 17, comprises:

- a plurality of welding units 29, in the specific case shown seven, each one adapted to weld at least one respective sleeved label sheet 2 along the respective seam portion 9;

- an auxiliary conveyor device 30, in particular arranged adjacent to main conveyor device 10, configured to advance welding units 29 along an endless advancement path S . In more detail, auxiliary conveyor device 30 comprises :

- an endless track 31 carrying welding units 29 in a manner to allow for advancement of welding units 29 along endless track 31 thereby defining endless advancement path S ; and

- a control unit 32 configured to control advancement of each welding unit 29 along endless advancement path S independently from the other welding units 29.

In the context of the present disclosure, the independent advancement of welding units 29 is to be understood in the sense that the advancement velocity of each welding unit 29 can be varied independently from the advancement velocities of the other welding units 29. This also means that the relative distances between, in particular neighboring, welding units 29 can be varied. It is to be noted, that the advancement velocities can be varied in certain limits, as none of welding units 29 is arranged on endless track 31 in a manner allowing to overtake any other welding unit 29.

In more detail, endless track 31 comprises:

- an operative branch 33 for advancing welding units 29 along an operative portion SI of endless advancement path S, in particular operative portion SI extends parallel to welding portion PI, even more particular being arc-shaped; wherein each welding unit 29 is configured to weld the respective sleeved label sheet 2 along the respective seam portion 9 during advancement along operative portion SI; and

- a return branch 34 for advancing welding units 29 along a return portion S2 of endless advancement path S so as to return welding units 29 back to operative portion SI .

Preferentially, control unit 32 is configured to control the advancement of each welding unit 29 along operative portion SI at a constant advancement velocity and to control the advancement of each welding unit 29 along the return portion S2 at a varying advancement velocity. In particular, control unit 32 is configured to control advancement of each welding unit 29 at least along a section of return portion S2 at a maximum advancement velocity being higher than the advancement velocity with which each welding unit 29 advances, in use, along the respective operative portion SI. In this way, it is possible to minimize the number of welding units 29 needed for sealing each one of sleeved label sheets 2 along the respective seam portions 9.

Preferentially, control unit 32 is configured to control the advancement of each welding unit 29 along operative portion SI such that these welding units 29 contemporaneously advancing, in use, along operative portion SI advance at a constant pitch (constant distance between neighboring welding units 29) and at a constant advancement velocity. In particular, the pitch and the advancement velocity is determined respectively by the distance between neighboring sleeved label sheets 2 and the advancement velocity of sleeved label sheets 2 along welding portion PI as each welding unit 29 must advance along operative portion SI so as to be adapted to weld the respective sleeved label sheet 2 along the respective seam portion 9. It is to be noted that the pitch between neighboring sleeved label sheets 2 is determined by the arrangement of treatment units 22.

In particular, the extension of operative portion SI (and, accordingly, of operative branch 33) is determined by the time needed to execute the welding of the respective seam portions 9. The extension of the operative portion SI (and the operative branch 33) is a function of e.g. the properties of the heat-shrinkage material of sleeved label sheets 2 and the technical characteristics of welding units 29.

Preferentially, control unit 32 is also configured to control the advancement of each welding unit 29 along return portion S2 so that these welding units 29 contemporaneously advancing, in use, along return portion S2 advance at varying distances from one another and at varying advancement velocities.

Preferentially, control unit 32 is configured to control an acceleration and a successive deceleration of welding units 29 while, in use, advancing along return portion S2. In particular, control unit 32 is configured to accelerate each welding unit 29 so that each welding unit 29 advances along a section of return portion S2 at the maximum advancement velocity and to decelerate each welding unit 29 so as to decelerate each welding unit 29 to the advancement velocity at which each welding unit 29 advances along operative portion Si. Preferentially, control unit 32 controls an acceleration of each welding unit 29 shortly after termination of welding the respective seam portion 9.

Preferentially, auxiliary conveyor device 30 comprises an actuation unit (not shown) having a plurality of coil elements (not shown) arranged along endless track 31. In particular, the actuation unit is controlled by control unit 32 and is configured to selectively interact with each welding unit 29 so as to actuate advancement of each welding unit 29 along endless advancement path S.

Preferentially, the actuation unit, in particular the coil elements are controlled by control unit 32 so as to generate electromagnetic fields selectively interacting with each welding unit 29 so as to selectively control advancement of each welding unit 29.

Preferably, each welding unit 29 is of the ultrasonic type; i.e. each welding unit 29 is configured to generate an ultrasonic wave for locally heating sleeved label sheets 2 along the respective seam portions 9.

Preferentially, each welding unit 29 comprises at least one magnetic or ferromagnetic element adapted to selectively cooperate with the coil elements, in particular the electromagnetic fields generated by the coil elements, so that each welding unit 29 is controllable to advance, in use, independently of the other welding units 29 along the endless advancement path S .

More specifically, each welding unit 29 comprises a moveable cart (not shown) carrying the respective magnetic or ferromagnetic element and being moveably coupled to endless track 31 and a welding head 35 mounted to the respective moveable cart and being adapted to weld the respective sleeved label sheet 2 along the respective seam portion 9, in particular, by means of ultrasonic waves.

In use, labeling machine 1 applies sleeved label sheets 2 onto bottles 3, in particular onto bottles 3 to be labelled.

In particular, the labeling process of bottles 3 comprises the following steps:

- a main advancement step during which sleeved label sheets 2 having one respective longitudinal seam portion 9 are advanced along label advancement path P;

- an auxiliary advancement step during which each welding unit 29 advances along endless advancement path S ; and

- a welding step during which each sleeved label sheet 2 is welded along the respective longitudinal seam portion 9 during advancement along welding portion PI by one respective welding unit 29 advancing along endless advancement path S . In more detail, during the main advancement step each sleeved label sheet 2 is advanced along label advancement path P by conveyor structure 23, in particular the conveyor carousel. In particular, during advancement along label advancement path P each sleeved label sheet 2 is retained at least along a portion of label advancement path P by the respective treatment unit 22, in particular by the respective mandrel 24 and/or the respective auxiliary suction member, preferentially by applying the respective suction force. Preferentially, during advancement along welding portion PI each sleeved label sheet 2 is retained by the respective treatment unit 22, in particular the respective mandrel 24.

In more detail, during the auxiliary advancement step each welding unit 29 advances along endless track 31 defining endless advancement path S.

Advantageously, during the auxiliary advancement step control unit 32 controls advancement of each welding unit 29 along endless advancement path S independently from the other welding units 29.

Preferentially, during the auxiliary advancement step control unit 32 controls advancement of each welding unit 29 at a constant advancement velocity while advancing along operative portion SI, in particular so that each welding unit 29 remains phases with respect to the respective sleeved label sheet 2 (i.e. each welding unit 29 remains aligned with respect to the respective sleeved label sheet 2) . Even more preferentially, during the auxiliary advancement step control unit 32 also controls advancement of each welding unit 29 along return portion S2 such that each welding unit 29 advances at varying advancement velocity, in particular during advancement along at least one section of return portion S2 each welding unit 29 is controlled to advance at the maximum advancement velocity being higher than the advancement velocity of each welding unit 29 along return portion S2.

More specifically, during the auxiliary advancement step while advancing along operative portion SI each welding unit 29 executes the respective welding step (i.e. while advancing along operative portion SI each welding unit 29 welds the respective sleeved label sheet 7 along operative portion SI) .

Preferentially, during the auxiliary advancement step control unit 32 controls the advancement of each welding unit 29 along operative portion SI such that these welding units 29 contemporaneously advancing along operative portion SI advance at a constant pitch (i.e. the distance between neighboring welding units 29 remains constant) and at a constant advancement velocity. In particular, the pitch and the advancement velocity are such that each welding unit 29 remains phased with respect to the respective sleeved label sheet 2 advancing along welding portion PI (or in other words, with the respective treatment unit 22) so as to allow for the welding of the respective seam portion 9. In other words, the pitch and the advancement velocity are such that each welding unit 29 can interact with the respective seam portion 9 of the respective sleeved label sheet 2 for the time needed to execute and to complete the welding step.

Preferentially, during the auxiliary advancement step each welding unit 29 also advances along return portion S2, in particular after termination of the respective welding step, so as to return each welding unit 29 back to operative portion SI. This allows to reposition each welding unit 29 so as to get ready for interacting with a new respective sleeved label sheet 2. Therefore, control unit 32 controls advancement of each welding unit 29 along return portion SI such that these welding units 29 contemporaneously advancing along return portion S2 advance along at least a section of return portion S2 at a maximum velocity being faster than the advancement velocity with which each welding unit 29 advances along operative portion SI.

In particular, control unit 32 controls each welding unit 29 such that welding units 29 (contemporaneously) advancing along return portion S2 advance at different advancement velocities, preferentially, also the distance between successive welding units 29 (contemporaneously) advancing along return portion S2 differs (i.e. the pitch between successive welding units 29 varies) .

Preferably, auxiliary advancement step comprises at least an acceleration sub-step during which each welding unit 29 is accelerated to the maximum advancement velocity while advancing along at least a section of return portion SI and at least a deceleration sub-step during which each welding unit 29 is decelerated, while advancing along at least another section of return portion S2, to an advancement velocity being the advancement velocity of the welding units 29 while advancing along operative portion Si. In particular, the acceleration sub-step is executed prior to the deceleration sub-step.

In more detail, during the welding step the respective welding head 35 contacts the respective seam portion 9 of the respective sleeved label sheet 2 and welds, in particular by heating the respective seam portion 9. Preferentially, each welding head 35 generates ultrasonic waves so as to weld the respective seam portion 9.

Preferentially, the labeling process also comprises a sleeved label forming step, in particular executed prior to the main advancement step, during which each sleeved label sheet 2 is formed from one respective label sheet

7.

In more detail, during the sleeved label forming step one respective single label sheet 7 is delivered to label supply station 11 and the respective sleeved label sheet 2 is obtained through overlapping the two respective lateral edges 8 with one another for obtaining the respective seam portion 9.

In further detail, each single label sheet 7 is delivered at supply station 11 to the respective treatment unit 22, in particular to the respective mandrel 24 being in the extracted configuration and the respective lateral edges 8 become overlapped through interaction with the respective treatment unit 22, in particular the respective mandrel 24 being in the extracted configuration. In even further detail, the respective lateral edge 8 defining the leading edge is delivered to the respective mandrel 24. As the mandrel 24 rotates around the respective central axis G and advances along the endless path the respective mandrel 24 winds-up the respective single label sheet 7 so that the respective lateral edge 8 defining the trailing edge becomes positioned over the leading edge .

Preferably, the labeling process, also comprises a receptacle advancement step during which each bottle 3 is advanced along receptacle advancement path Q. Even more preferably, the labeling process also comprises a receptacle feeding step during which each bottle 3, in particular each bottle 3 to be labelled, is fed to main conveyor device 10 at inlet station 12 and an receptacle discharge step during which each bottle 3, in particular each labelled bottle 3, is discharged from main conveyor device 10 at outlet station 13.

More specifically, during the receptacle advancement step, each bottle 3 is supported by the respective treatment unit 22, in particular is carried by the respective mandrel 24.

Even more specifically, during the receptacle advancement step each bottle 3 is fed to inlet station 12 by the inlet conveyor, in particular the inlet star wheel 20 and each bottle 3 is discharged from main conveyor device 10 to the outlet conveyor, in particular outlet star wheel 21 at outlet station 13.

Preferably, the labeling process also comprises a sleeved label sheet transfer step, in particular executed during advancement of the respective sleeved label sheet 2 along transfer portion P2, during which each sleeved label sheet 2 is transferred to the respective bottle 3, so as to at least partially superimpose the respective bottle 3. In particular, the sleeved label sheet transfer step is executed after welding of the respective seam portion 9.

In more detail, during the sleeved label sheet transfer step the respective mandrel 24 is moved from the extracted configuration to the retracted configuration. At the same time, the respective auxiliary suction member is activated and the suction through the suction holes of the respective mandrel 24 is deactivated. During the movement of the respective mandrel 24 from the extracted configuration to the retracted configuration, the respective bottle 3 is moved from the first elevation level to the second elevation level thereby the respective sleeved label sheet 2 becomes imposed on the respective bottle 2 (in other words, during the movement from the first elevation level to the second elevation level, the respective bottle 3 enters into the cylindrically shaped sleeved label sheet 2) . Preferentially, the labeling process also comprises a heating step during which each sleeved label sheet 2 is exposed to a thermal treatment so as to induce a shrinkage of the sleeved label sheet 2, onto bottle 3 in a known manner .

In particular, the heating step is executed by heating apparatus 19 after the sleeved label sheet transfer step.

The advantages of labeling machine 1 and the disclosed labeling method, according to the present invention will be clear from the foregoing description.

First of all, labeling machine 1, in particular welding apparatus 17, requires a reduced number of welding units 29 and therewith a reduced number of welding heads 35. This allows to significantly reduce the costs associated to the welding apparatus 17 of labeling machine 1. This is achieved as the welding apparatus 17 is detached from the main conveyor device 10 and is arranged adjacent to the main conveyor device 10. As auxiliary conveying device 30 is configured to advance welding units 29 along endless advancement path S it is possible to repeatedly advance welding units 29 parallel to the advancing sleeved label sheets 2. Thus, it is not necessary to associate one respective welding unit having one respective welding head 35 to each treatment unit 22 as it is the case in the state-of-the-art labeling machines known.

A further advantage resides in the fact that control unit 32 controls advancement of welding units 29 independently from one another. This allows to selectively vary the advancement velocity of welding units 29 and to also vary the distance between successive welding units 29. Only these welding units 29 welding the respective seam portion 9 are required to advance at a constant pitch and at a constant advancement velocity determined by the pitch and the advancement velocity of the sleeved label sheets 2 to be welded. As the welding units 29 can be accelerated after the termination of the welding process, it is possible to return the welding units back to be ready to weld a new sleeved label sheet 2. This would not be possible in the case, the welding units 29 would always advance at a constant pitch and at constant advancement velocity independently of whether they are active (they execute a welding step) or whether they are inactive.

Clearly, changes may be made to labeling machine 1 and the labeling method, as described herein without, however, departing from the scope of protection as defined in the accompanying claims.