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CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority from Italian patent application no . 102020000021748 filed on 15/ 09/2020 , the entire disclosure of which is incorporated herein by reference .

TECHNICAL FIELD

The present invention relates to a cutting unit and method to remove a strap from a wall of a pack, in particular, of smoking articles .

The present invention finds advantageous application in a packing machine ( for example a cellophane wrapping machine ) for manufacturing a pack of cigarettes , known as "book-pack" , to which the following disclosure will make explicit reference without thereby any loss of generality .

PRIOR ART

A "book-pack" pack of cigarettes comprises ( at least ) two containers , which house respective groups of wrapped cigarettes , have respective open upper ends , and are hinged to one another so as to rotate between a closed configuration, in which the two containers are overlapping one another, and an open configuration, in which the two containers are separated; furthermore , a lid is provided, which is hinged to a rear container and, when in a closed position, embraces the upper part of both the containers .

An example of a "book-pack" pack of cigarettes is provided in the patent application EP1616795A1 or in the patent application EP1829783A1 .

The production of a "book-pack" pack of cigarettes involves forming the two containers by using two corresponding blanks that are folded around respective groups of wrapped cigarettes , coupling ( overlapping) the two containers , and then folding a third blank, around the two coupled ( overlapping) containers that j oins the two containers and creates the common lid .

After folding the third blank it is necessary to make a cut on the bottom wall of the "book-pack" pack of cigarettes so as to allow the separation of the two containers ( i . e . , to allow the two containers to rotate relative to one another) ; normally a double cut is performed ( i . e . , two close and parallel cuts ) to remove a strap ( strip ) from the bottom wall so as to create a clear separation between the two containers . For this purpose , a cutting unit is used, which is provided with two parallel and adj acent rotary blades , which are partially housed in a collection chamber in which a suction action is performed that should capture and remove the strap as soon as the strap has been separated from the rest of the bottom wall of a "book-pack" pack of cigarettes . However, it is not infrequent that even after the cut made by the two rotary blades the strap remains stuck in the bottom wall of a "book-pack" pack of cigarettes and therefore is not removed by suction; consequently, downstream of the cutting unit some "book-pack" pack of cigarettes still have the strap on the bottom, which can be more or less in position . This can generate various problems such as the loss of the strap in the machine be fore the application of the transparent plastic overwrapping or the wrapping (with the transparent plastic overwrapping) of the strap together with the pack in completely random positions giving the final user the impression of a poor-quality pack of cigarettes .

The patent application US2011049781A1 describes a system for cutting and stacking sheets for the formation of books .

DESCRIPTION OF THE INVENTION

The obj ect of the present invention is to provide a cutting unit and a method to remove a strap from a wall of a pack, in particular, of smoking articles , which allow the strap to be removed after cutting and, at the same time , are easy and inexpensive to manufacture .

According to the present invention a cutting unit and a method to remove a strap from a wall of a pack, in particular , of smoking articles , are provided, according to what is claimed in the attached claims .

The claims describe embodiments of the present invention forming an integral part of the present description .

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the attached drawings , which illustrate a non-limiting embodiment thereof , wherein :

• Figure 1 is a perspective view of a "book-pack" pack of cigarettes in a closed configuration;

• Figure 2 is a perspective view of the "book-pack" pack of cigarettes of Figure 1 in an open configuration;

• Figure 3 is a schematic and plan view of a cutting unit to remove a strap from a bottom wall of the "book-pack" pack of cigarettes of Figure 1 ;

• Figure 4 is a perspective view with parts removed for clarity of the cutting unit of Figure 3 ;

• Figure 5 is a schematic and side view of the cutting unit of Figure 3 ;

• Figure 6 is a view, on an enlarged scale , of a detail of Figure 5 ; and

• Figures 7 , 8 and 9 are three schematic and plan views of part of the cutting unit of Figure 3 in three respective operating moments .

PREFERRED EMBODIMENTS OF THE INVENTION

In Figures 1 and 2 , number 1 denotes as a whole a "book-pack" pack of cigarettes that comprises two containers 2 , which house respective groups of wrapped cigarettes , have respective upper open ends, and are hinged to one another so as to rotate between a closed configuration (illustrated in Figure 1) , in which the two containers 2 are overlapping one another, and an open configuration (illustrated in Figure 2) , in which the two containers 2 are separated; furthermore, a lid 3 is provided, which is hinged to a rear container 2 and, when in a closed position, embraces the upper part of both containers 2.

The production of the "book-pack" pack 1 of cigarettes involves forming the two containers 2 using two corresponding blanks that are folded around the respective groups of wrapped cigarettes, coupling (overlapping) the two containers 2, and then folding a third blank, around the two coupled (overlapping) containers 2, which joins the two containers 2 and creates the common lid 3.

After folding the third blank it is necessary to make a cut on the bottom wall 4 of the "book-pack" pack of cigarettes so as to allow the separation of the two containers 2 (i.e., to allow the two containers 2 to rotate relative to one another) .

In Figures 3 and 4, number 5 denotes as a whole a cutting unit which, in order to create a clear separation between the two containers 2, performs a double cut (i.e., two close and parallel cuts) so as to remove a strap 6 (strip) from the bottom wall 4 of a pack 1 of cigarettes which is fed along a straight path P; that is, the cutting unit 5 removes a relatively thin central part (the strap 6) from the bottom wall 4 of a pack 1 of cigarettes so as to divide the two containers 2.

The cutting unit 5 comprises two parallel and adjacent rotary blades 7 which are arranged horizontally and are mounted in a rotatable manner around a same vertical rotation axis 8 (i.e., the two rotary blades 7 are identical and coaxial to one another) ; in use, the two rotary blades 7 make two parallel cuts on the bottom wall 4 which separate the strap 6 from the rest of the bottom wall 4. In the embodiment illustrated in the attached figures, the two rotary blades 7, parallel to one another, rotate around the same vertical rotation axis 8 (i.e., they are coaxial) and in use make two parallel cuts on the bottom wall 4 that separate the strap 6 from the rest of the bottom wall 4. According to a different and equivalent embodiment, not illustrated, the two rotary blades 7 are inclined relative to one another (therefore they are both inclined in an opposite manner relative to a horizontal plane) , they rotate around two different rotation axes 8 not parallel to one another (and both inclined in opposite manner relative to a vertical plane) , and in use they make, on the bottom wall 4, two parallel cuts which separate the strap 6 from the rest of the bottom wall 4. In other words, the two rotary blades 7 are mounted in a rotatable manner around respective rotation axes 8, which can be mutually coincident or different. According to a further embodiment not illustrated, the rotary blades 7 in use can make on the bottom wall 4 two cuts which are not (perfectly) parallel to one another (i.e., slightly inclined towards one another) which separate the strap 6 from the rest of the bottom wall 4 and in this case the strap 6 has a trapezoidal or triangular shape instead of a rectangular shape .

According to a further embodiment not illustrated, the two rotary blades 7 could have a predominantly vertical orientation rather than a predominantly horizontal orientation as illustrated in the attached figures. Furthermore, the two rotary blades 7 may not be perfectly identical (twins) and therefore having differences one relative to the other.

Finally, the two cuts, which separate the strap 6 from the rest of the bottom wall 4 and that are made by the two rotary blades 7 may not be perfectly parallel to one another (i.e., they may be slightly convergent or divergent one relative to the other) . Furthermore , the cutting unit 5 comprises an extractor element 9, which is arranged close to the two rotary blades 7 so as to intercept the strap 6 and accompany (push) the strap 6 away from the bottom wall 4 ( obviously on the opposite side of the pack 1 of cigarettes ) so as to separate the strap 6 from the pack 1 of cigarettes .

In particular, the extractor element 9 comprises a point 10 (better illustrated in Figures 7 , 8 and 9 ) , which firstly intercepts the strap 6 ( i . e . , it is arranged upstream relative to the feeding direction of the pack 1 of cigarettes along the path P ) and has a width smaller than a width of the strap 6 , namely smaller than a distance between the two rotary blades 7 ; by way of example , the distance between the two rotary blades 7 (hence the width of the strap 6 ) could be about 5 tenths of a millimetre while the width of the point 10 could be about 3-4 tenths of a millimetre .

In other words , the extractor element 9 is positioned near the periphery of the rotary blades 7 so that the point 10 of the extractor element 9 touches the edge of said rotary blades 7 to intercept the strap 6 and accompany the strap 6 away from the bottom wall 4 .

The extractor element 9 has the shape of an arc of a circle and is mounted so as to rotate around a rotation axis 11 parallel to the rotation axis 8 ; in the embodiment illustrated in the attached figures , the rotation axi s 11 of the extractor element 9 is coaxial ( i . e . , coincident ) with the rotation axis 8 of the rotary blades 7 while according to other embodiments the rotation axis 11 of the extractor element 9 is parallel and spaced apart from the rotation axis 8 of the rotary blades 7 .

The cutting unit 5 comprises an actuator device 12 ( schematically i llustrated in Figure 3 ) which carries out both the rotation of the two rotary blades 7 around the rotation axis 8 , and the rotation of the extractor element 9 around the rotation axis 11 . Preferably, the actuator device 12 comprises a first electric motor which rotates the two rotary blades 7 and a second electric motor (mechanically independent from the first electric motor ) which rotates the extractor element 9 with a rotation speed di f ferent from the two rotary blades 7 ; by way of example , the two rotary blades 7 rotate , for example , at a rotation speed of about 1500 rpm which always remains constant while the extractor element 9 rotates synchronously with the work cycle of the cutting unit 5 , i . e . , a rotation speed of about 100-400 rpm which is continuously variable to follow the work cycle of the cutting unit 5 . According to a di f ferent embodiment , the actuator device 12 comprises a single electric motor generating (by means of suitable mechanical transmissions ) both the rotation motion of the two rotary blades 7 around the rotation axis 8 and the rotation motion of the extractor element 9 around the rotation axis 11 .

In the embodiment illustrated in Figures 7 , 8 and 9 , the actuator device 12 rotates the extractor element 9 between an initial position ( illustrated in Figure 8 ) in which the point 10 of the extractor element 9 is arranged in contact with the bottom wall 4 and a final position ( illustrated in Figure 9 ) in which the point 10 of the extractor element 9 is at a distance other than zero from the bottom wall 4 ; this movement of the extractor element 9 progres sively moving away from the bottom wall 4 allows to accompany (push) the strap 6 away from the bottom wall 4 allowing the strap 6 to be adequately separated ( extracted) from the bottom wall 4 .

Furthermore , in the embodiment illustrated in Figures 7 , 8 and 9, the actuator device 12 rotates the extractor element 9 causing the extractor element 9 to travel a work stroke , (which starts from the position illustrated in Figure 7 ) during which the extractor element 9 moves along the path P with the same direction as the pack 1 of cigarettes and with a feeding speed lower than a feeding speed of the pack 1 of cigarettes ( so that the extractor element 9 is reached by the arriving pack 1 of cigarettes and that therefore the extractor element 9 can engage the bottom wall 4 of the pack 1 of cigarettes ) , and a return stroke , during which the extractor element 9 moves along the path P in an opposite direction to the pack 1 of cigarettes (passing from the position illustrated in Figure 9 to the position illustrated in Figure 7 ) . In other words , in the work stroke , the extractor element 9 is located in front of the pack 1 of cigarettes and advances along the path P with a speed lower than a speed of the pack 1 of cigarettes so as to be reached by the pack 1 of cigarettes and therefore being able to engage the bottom wall 4 of the pack 1 of cigarettes ; when the extractor element 9 is reached by the pack 1 of cigarettes and the point 10 of the extractor element 9 engages the strap 6 ( as illustrated in Figure 8 ) , the extractor element 9 moves away from the bottom wall 4 of the pack 1 of cigarettes causing the strap 6 to gradually move away from the bottom wall 4 of the pack 1 of cigarettes ( as illustrated in Figure 9 ) .

This movement of the extractor element 9 can be obtained both if the actuator device 12 rotates the extractor element 9 back and forth ( therefore without ever allowing the extractor element 9 to make a complete turn) , and i f the actuator device 12 rotates the extractor element 9 always in the same direction ( thus causing the extractor element 9 to make a succession of complete turns ) . I f the actuator device 12 rotates the extractor element 9 back and forth, then the actuator device 12 cyclically reverses the rotation direction of the extractor element 9 , always keeping the extractor element 9 close to the path P ; on the other hand, i f the actuator device 12 rotates the extractor element 9 always in the same direction, then the extractor element 9 travels the return stroke moving away from the path P and passing on the other side of the rotary blades 7 relative to the path P . Generally it is preferable that the actuator device 12 cyclically reverses the rotation direction of the extractor element 9 ( i . e . , that the extractor element 9 goes back and forth) as this law of motion allows only the point 10 of the extractor element 9 to be made very thin ( since it is the only part of the extractor element 9 that must be arranged between the two containers 2 ) whereas the rest of the extractor element 9 can be wider and therefore mechanically more robust ; on the other hand, when the actuator device 12 rotates the extractor element 9 always in the same direction ( thus causing the extractor element 9 to make a succession of complete turns ) the extractor element 9 must be overall narrower for reasons of space and therefore mechanically less robust .

During the work stroke , the extractor element 9 moves along the path P with a speed ( slightly) lower than the speed of the pack 1 of cigarettes , therefore the impact between the point 10 of the extractor element 9 and the bottom wall 4 occurs at low relative speed ( therefore in a gentle and not traumatic way) .

According to a di f ferent embodiment not illustrated, the extractor element 9 could not make any movement along the path P and in this case the impact between the point 10 of the extractor element 9 and the bottom wall 4 occurs at a higher relative speed ( the extractor element 9 is stationary relative to the path P, therefore the impact occurs at the speed of the pack 1 of cigarettes ) ; this alternative can expose the bottom wall 4 to some risk of suf fering unwanted dents by the impact with the point 10 of the extractor element 9 but it is still feasible . In this embodiment , the extractor element 9 could maintain movement along a direction perpendicular to the path P between the initial position ( illustrated in Figure 8 ) , in which the point 10 of the extractor element 9 is arranged in contact with the bottom wall 4 and the final position ( illustrated in Figure 9 ) , in which the point 10 of the extractor element 9 is at a distance other than zero from the bottom wall 4 ; alternatively, the extractor element 9 could be completely stationary, that is , it cannot move either parallel to the path P, or perpendicular to the path P .

In the embodiment illustrated in the attached figures , the actuator device 12 gives the extractor element 9 a rotation movement around the rotation axis 11 ; according to a di f ferent embodiment not illustrated, the actuator device 12 imparts to the extractor element 9 a linear translation movement along a direction parallel to the path P ( to travel alternatively the work stroke and the return stroke ) and also along a direction perpendicular to the path P ( to move between the initial position and the final position) .

As illustrated in Figures 3 and 4 , the cutting unit 5 comprises a sucking duct 13 ( i . e . , connected to a suction source ) , which is designed to suck the strap 6 , which was pushed away from the bottom wall 4 by the extractor element 9 . In detail , the sucking duct 13 has an initial end 14 which is arranged at the rotary blades 7 and is configured to contain at least a portion of the extractor element 9 ; in other words , the extractor element 9 moves inside the initial end 14 of the sucking duct 13 . The function of the sucking duct 13 is to convey by suction the strap 6 which has been separated from the bottom wall 4 so as to bring the strap 6 into a suitable collection area (not illustrated) . By way of example , the suction in the sucking duct 13 can be created by using an impeller or a flow accelerator . In particular, the initial end 14 of the sucking duct 13 has an input opening 15 which faces the bottom wall 4 and through which the extractor element 9 passes .

According to a preferred embodiment , the initial end 14 of the sucking duct 13 has a conical shape having the minimum dimension at the input opening 15 ( i . e . , having a dimension which progressively widens moving away from the rotary blades 7 so as to have the maximum depression at the rotary blades 7 ) .

According to a possible embodiment illustrated in Figure 4 , the cutting unit 5 comprises a cleaning device 16 ( i . e . , a sort of scraper ) which i s arranged in a fixed position around the two rotary blades 7 , at a small distance from the two rotary blades 7 , and has the function of cleaning the two rotary blades 7 from possible foreign elements (pieces of cardboard of the bottom wall 4 ) which have remained stuck between the two rotary blades 7 or sticking to a rotary blade 7 . In other words , the cleaning device 16 separates from the rotary blades 7 any foreign elements (pieces of cardboard of the bottom wall 4 ) which have remained stuck between the two rotary blades 7 or sticking to a rotary blade 7 .

According to what is illustrated in Figures 3 and 4 , the pack 1 of cigarettes is fed along the path P by a conveyor provided with two fixed containing guides 17 between which the pack 1 of cigarettes is located; in particular, a fixed guide 17 against which the bottom wall 4 scrapes , is provided with a through opening through which the two rotary blades 7 are arranged ( for this purpose , the through opening of the fixed guide 17 is slightly wider than the pair of rotary blades 7 to allow their insertion beyond the fixed guide 17 with a minimum clearance ) .

The embodiments described here can be combined with one another without departing from the scope of the present invention .

The cutting unit 1 described above has numerous advantages .

Above all , the cutting unit 1 described above makes it possible to ensure the removal of the strap 6 after cutting, preventing the strap 6 ( or a piece of the strap 6 ) from remaining in contact with the bottom wall 4 of the pack 1 of cigarettes .

Furthermore , the cutting unit 1 described above is simple and inexpensive to manufacture as compared to a similar known cutting unit , it requires quick modi fications using commercial pieces or pieces that can be easily obtained with standard mechanical processing.