WO2014068521A2

WO2014068521A2 - Unit and method for applying an inclined tear strip to a sheet of wrapping material

Info

Publication number: WO2014068521A2
Application number: PCT/IB2013/059830
Authority: WO
Inventors: Francesco Bertuzzi; Marco PARMEGGIANI; Luca Federici
Original assignee: G.D Societa' Per Azioni
Priority date: 2012-10-31
Filing date: 2013-10-31
Publication date: 2014-05-08
Also published as: DE112013002579T5; ITBO20120595A1; WO2014068521A3; WO2014068521A8

Abstract

A unit and method for applying a tear strip (3) to a sheet (2) of wrapping material, wherein an application conveyor (5) has at least one suction seat (6) for retaining the tear strip (3), and moves the suction seat (6) cyclically along an application path (PI); a feed conveyor (8) feeds the sheet (2) of wrapping material along a feed path (P2) and through an application station (SI), where the sheet (2) of wrapping material receives the tear strip (3); the application conveyor (5) is separate from and independent of the feed conveyor (8); and, at the application station (SI), a first actuating device (9) imparts an application movement, which is a relative movement between the suction seat (6) and the feed conveyor (8) and perpendicular to the application path (PI), to bring the tear strip (3) into contact with, and so apply the tear strip (3) to, the sheet (2) of wrapping material.

Description

UNIT AND METHOD FOR APPLYING AN INCLINED TEAR STRIP TO A SHEET OF WRAPPING MATERIAL

TECHNICAL FIELD

The present invention relates to a unit and method for applying an inclined tear strip to _. a sheet of wrapping material.

In the following description, reference is made, for the sake of simplicity and purely by way of a non- limiting example, to a sheet of transparent wrapping material for overwrapping a packet of cigarettes.

BACKGROUND ART

Patent Application EPO601583A1 describes part of a packing machine for producing packets of cigarettes, wherein each packet of cigarettes is wrapped in a sheet of transparent wrapping material to form a sealed, protective overwrap. Each sheet of wrapping material has a tear strip by which to tear off the sealed, protective overwrap when unsealing the packet of cigarettes. More specifically, the tear strip is inclined with respect to the sheet of wrapping material (i.e. is not parallel to any of the edges of the sheet) .

The packing machine comprises a unit for applying inclined tear strips to sheets of wrapping material, and wherein each tear strip is applied 'at an angle' with respect to the sheet of wrapping material (i.e. is not parallel to any of the edges of the sheet) . The application unit comprises an . applicator drum,^' about which a main continuous strip of successive sheets of wrapping material winds. Upstream from where it contacts the main continuous strip, the outer surface of the applicator drum is applied with successive tear strips, which are retained by suction inside respective suction seats, and each have a gummed outward-facing side. As the main continuous strip winds about the applicator drum, the gummed sides of the tear strips come into contact with the main continuous strip to gum the tear strips to the main continuous strip. The tear strips are deposited onto the outer surface of the applicator drum by a cutting device, which successively cuts the tear strips crosswise off a secondary continuous strip gummed (i.e. coated with adhesive) beforehand.

The application unit described in Patent Application EPO601583A1, however, has several drawbacks, by not allowing for high operating speeds (i.e. producing a large number of packets of cigarettes per unit time) while still maintaining good quality (i.e. no significant errors in the position of the tear strips on the sheets of wrapping material) .

Patent Application EP0773165A1 describes a packing machine for producing packets of cigarettes, wherein each packet of cigarettes is wrapped in a sheet of transparent wrapping material to form a sealed, protective overwrap. Each sheet of wrapping material has a tear strip, by which to tear off the sealed, protective overwrap when unsealing the packet of cigarettes; and two small labels with graphics and/or writing. The labels are applied to each sheet of wrapping material at a first application station equipped with an applicator drum fitted with a radially movable suction head, which, in use, is moved radially outwards of the applicator drum to apply a corresponding label to the sheet of wrapping material. A tear strip is applied to each sheet of wrapping material at a standard second application station located downstream from the first application station and comprising two opposed rollers, between which the sheet of wrapping material and the tear strip are fed to press the tear strip onto the sheet of wrapping material.

DESCRIPTION OF THE INVENTION

It is an object of the present invention to provide a unit and method for applying an inclined tear strip to a sheet of wrapping material, designed to eliminate the above drawbacks, and which in particular are cheap and easy to implement.

According to the present invention, there are provided a unit and method for applying an inclined tear strip to a sheet of wrapping material, as claimed in the W

accompanying Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

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

Figure 1 shows a schematic view in perspective of a packet of cigarettes to which is applied a sheet of transparent overwrap with an inclined tear strip;

Figure 2 shows a schematic view in perspective of an application unit, in accordance with the present invention, for applying an inclined tear strip to a sheet of wrapping material;

Figure 3 shows a front view, with parts removed for clarity, of an application conveyor of the Figure 2 application unit;

Figure 4 shows a front cross section, with parts removed for clarity, of the Figure 3 application conveyor;

Figure 5 shows a further schematic view in perspective of the Figure 2 application unit;

Figure 6 shows a . schematic of a different embodiment of the Figure 2 application unit.

PREFERRED EMBODIMENTS OF THE INVENTION

Number 1 in Figure 1 indicates a packet of cigarettes, to which a sheet 2 of transparent wrapping material with an inclined tear strip 3 (i.e. a tear strip 3 which is not parallel to any of the edges of sheet 2 of wrapping material) is applied to form a sealed transparent protective overwrap. Tear strip 3 serves to tear off the sealed protective overwrap when unsealing packet 1 of cigarettes, and so extends the full width of sheet 2 of wrapping material.

Number 4 in Figure 2 indicates as a whole an application unit, on which successive inclined tear strips 3 are applied to corresponding sheets 2 of transparent wrapping material.

Application unit 4 comprises an application conveyor 5 with a number of suction seats 6, each of which is designed to retain a respective tear ^'strip 3 and is moved cyclically along a circular application path PI.. Application unit 4 comprises an application station SI located along application path PI, and where each tear strip 3, retained by suction seat 6 on application conveyor 5, is applied to a corresponding sheet 2 of wrapping material fed through application station SI by a feed conveyor 8. Feed conveyor 8 is separate and independent of application conveyor 5, and feeds sheets 2 of wrapping material successively along a feed path P2 and through application station SI, where each sheet 2 of wrapping material receives a corresponding tear strip 3.

At application station SI, application path PI forms an acute angle with, as opposed to being parallel to, feed path P2, so that each tear strip 3 is applied at an angle to corresponding sheet 2 of wrapping material (as shown clearly in Figure 1) .

At application station SI, an actuating device 9

(shown in Figures 4 and 6) produces a relative application movement between each suction seat 6 and feed conveyor 8 and perpendicular to application path PI to bring tear strip 3 into contact with, and so apply it to, sheet 2 of wrapping material. Obviously, during each application movement, suction through the suction seat 6 carrying tear strip 3 is cut off (temporarily) to release tear strip 3 from suction seat 6 onto sheet 2 of wrapping material.

In the Figure 2-5 embodiment, actuating device 9 only moves each suction seat 6 perpendicularly to application path PI to bring tear strip 3 into contact with sheet 2 of wrapping material. In other words, at application station SI, each sheet 2 of wrapping material remains stationary, and tear strip 3 carried by suction seat 6 is moved towards sheet 2 of wrapping material to perform the application movement. In the Figure 6 embodiment, which is perfectly equivalent to the one in Figures 2-5, actuating device 9 only moves each sheet 2 of wrapping material perpendicularly to application path PI to bring sheet 2 of wrapping material into contact with tear strip 3. In other words, at application station SI, each tear strip 3, carried by suction seat 6, remains stationary, and sheet 2 of wrapping material is moved towards tear strip 3 to perform the application movement.

As shown in Figure 2, feed conveyor 8 feeds a main strip 10, containing a succession of sheets 2 of wrapping material, through application station SI. Feed conveyor 8 feeds main strip 10 through application station SI in an intermittent movement, which comprises a stop stage, in which each sheet 2 of wrapping material remains stationary at application station SI as corresponding tear strip 3 is applied. At a cutting station (not shown) downstream from application station SI, sheets 2 of wrapping material are cut successively crosswise off main strip 10, for supply to a wrapping station (not shown) where they are wrapped about packets 1 of cigarettes.

In a preferred embodiment, feed conveyor 8 comprises an actuating device 11 (shown schematically in Figure 2) which imparts a constant travelling speed to main strip 10; and a tensioning device 12 located close to application station SI to cyclically decelerate and accelerate main strip 10 and so produce an intermittent movement of main strip 10 at application station SI. In other words, outside application station SI, main strip 10 moves continuously (i.e. at constant travelling speed), whereas, at application station SI and by means of tensioning device 12, main strip 10 moves intermittently .

Tensioning device 12 comprises two semicircular diverting members 13, which are located at opposite ends of application station SI, are connected mechanically to each other by a common supporting frame, and are positioned contacting main strip 10; and an actuating device 14 (shown schematically in Figure 2) for imparting a reciprocating movement to the supporting frame. In a preferred (non-limiting) embodiment, actuating device 14 comprises a connecting rod-crank system for converting rotation to the reciprocating movement imparted to the supporting frame.

Application unit 4 comprises a supply conveyor 15 (shown schematically in Figures 2 and 3 and in more detail in Figure 6) which feeds a secondary strip 16, containing a succession of tear strips 3, to application conveyor 5 at an input station S2 of application path PI; and a cutting device 17 connected to application conveyor 5 to successively cut tear strips 3 crosswise off secondary strip 16. Cutting device 17 is located downstream from input station S2 of application path PI to cut each tear strip 3 off secondary strip 16 after tear strip 3 is engaged by suction seat 6. A known gumming device (not shown) is preferably located along supply conveyor 15 to gum one face of secondary strip 16 and so glue each tear strip 3 to corresponding sheet 2 of wrapping material. Obviously, the gummed face of secondary strip 16 faces outwards as secondary strip 16 winds about application conveyor 5.

In the Figure 2-5 embodiment, application conveyor 5 comprises a drum 18 mounted to rotate about a central axis of rotation 19 and supporting a number of peripheral heads 20, each supporting a respective suction seat 6. In a preferred embodiment shown more clearly in Figure 4, each head 20 is fitted to drum 18 to move radially between a rest position outside application station SI, and a work position inside application station SI. Each head 20 is located within the perimeter of drum 18 in the rest position, and is located outside, i.e. projects radially from, the perimeter of drum 18 in the work position.

Actuating device 9 moves each head 20, at application station SI, radially to impart the application movement to corresponding suction seat 6. More specifically, for each head 20, actuating device 9 comprises a respective elastic member 21, in particular a coil spring, which pushes head 20 radially towards central axis of rotation 19, i.e. into the rest position. Actuating device 9 also comprises a pusher 22 (common to all of heads 20) located in a fixed position inside the centre of drum 18 to push each head 20 at application station SI radially, in opposition _. to elastic member 21. Each elastic member 21, i.e. each coil spring, is compressed when head 20 is pushed radially by pusher 22, i.e. is pushed radially by pusher 22 from the rest to the work position. So the elastic force generated by each elastic member 21 tends to push head 20 into the rest position.

In a preferred embodiment, in addition to moving head 20 from the rest to the work position, the radial movement imparted to each head 20 by actuating device 9 also cuts off suction (temporarily) through the suction seat 6 carrying tear strip 3, to release tear strip 3 from suction seat 6 onto sheet 2 of wrapping material. More specifically, the radial movement imparted to each head 20 by actuating device 9 disconnects suction seat 6 (temporarily) from a suction source, and connects it (temporarily) to the outside (or to a blow device) .

As shown in Figures 2-4, cutting device 17 comprises four taut, heated wires 23, each of which cyclically cuts secondary strip 16 crosswise; and an actuating device 24 for moving heated wires 23 with respect to secondary strip 16. More specifically, actuating device 24 comprises a drum 25 located alongside drum 18 of application conveyor 5, and mounted to rotate about a central axis of rotation 26 parallel to axis of rotation 19 of drum 18. In a preferred embodiment, actuating device 24 is connected mechanically to application conveyor 5 to move heated wires 23 together with application conveyor 5. In other words, rotation of drum 18 of application conveyor 5 about axis of rotation 19 is connected mechanically ^' to rotation of drum 25 of cutting device 17 about axis of rotation 26, so rotation of drum 25 is synchronized and in phase with rotation of drum 18 at all times.

Figure 6 shows a different embodiment of application unit 4, in which application conveyor 5 comprises a conveyor belt 27 looped about two end pulleys 28 and supporting suction seats 6. Cutting device 17 comprises two mutually cooperating drums, of which one supports at least one blade, and the other a counter-blade; and secondary strip 16 is fed between the two drums of cutting device 17, and is cut cyclically crosswise to cut tear strips 3 off secondary strip 16. Actuating device 9 comprises a lifter 29 which moves straight up and down to define the application movement, and is connected to feed conveyor 8 (not shown in Figure 6) to raise main strip 10 cyclically and so bring sheets 2 of wrapping material into contact with the corresponding tear strips 3 on application conveyor 5.

Operation of application unit 4 will now be described with reference to Figure 2.

Supply conveyor 15 feeds secondary strip 16 to input station S2 of application path PI, so secondary strip 16 is engaged cyclically by suction seats 6 on application conveyor 5. The portions of secondary strip 16 engaged by suction seats 6 on application conveyor 5 are cut cyclically crosswise by cutting device 17 to cut tear strips 3 off secondary strip 16. In other words, each crosswise cut is made between two suction seats 6 on application conveyor 5, so each tear strip 3, once cut off secondary strip 16, is firmly retained by a corresponding suction seat 6.

The movement of application conveyor 5 feeds suction seats 6, carrying tear strips 3, to application station SI. As each suction seat 6 reaches application station SI, actuating device 9 (Figures 4 and 6) produces an application movement perpendicular to application path PI, to bring tear strip 3 into contact with, and so apply it to, sheet 2 of wrapping material. Obviously, during each application movement, suction through the suction seat 6 carrying tear strip 3 is cut off (temporarily) to release tear strip 3 from suction seat 6 onto sheet 2 of wrapping material .

At application station SI, main strip 10 of sheets 2 of wrapping material remains stationary for as long as it takes to apply the tear strip 3. Application unit 4 described has numerous advantages.

In particular, application unit 4 described allows for high operating speeds (i.e. for applying a large number of tear strips 3 to sheets 2 of wrapping material per unit time) while still maintaining good quality (i.e. no. significant errors in the position of tear strips 3 on the respective sheets of wrapping material) .

Moreover, application unit 4 described is cheap and easy to produce, in that all the moving parts can be operated by a single motor with straightforward mechanical power transmissions.

Claims

1) An application unit (4) for applying to a sheet (2) of wrapping material an inclined tear strip . (3) by which to tear off the sheet (2) of wrapping material (2), and which extends the full width of the sheet (2) of wrapping material; the application unit (4) comprising :

an application conveyor (5), which has at least one suction seat (6) for retaining the tear strip (3), and moves the suction seat (6) cyclically along an application path (PI);

an application station (SI) located along the application path (PI) and where the tear strip (3) retained by the suction seat (6) of the application conveyor (5) is applied to the sheet (2) of wrapping material; and

a feed conveyor (8), which feeds the sheet (2) of wrapping material along a feed path (P2) and through the application station (SI), where the sheet (2) of wrapping material receives the tear strip (3) ;

at the application station (SI), the application path (PI) not being parallel to the feed path (P2), but forming an acute angle with the feed path (P2) ;

the application unit (4) being characterized in that: the application conveyor (5) is separate from and independent of the feed conveyor (8); and

at the application station (SI) , a first actuating device (9) imparts an application movement, which is a relative movement between the suction seat (6) and the feed conveyor (8) and perpendicular to the application path (PI), to bring the tear strip (3) into contact with, and so apply the tear strip (3) to, the sheet (2) of wrapping material.

2) An application unit (4) as claimed in Claim 1, wherein the feed conveyor (8) feeds a main strip (10), containing the sheet (2) of wrapping material, through the application station (SI) in an intermittent .movement comprising a stop stage in which the sheet (2) of wrapping material is stationary at the application station (SI) .

3) An application unit (4) as claimed in Claim 2, wherein the feed conveyor (8) comprises:

a second actuating device (11), which imparts a constant travelling speed to the main strip (10); and a tensioning device (12) located close to the application station (SI) to cyclically decelerate and accelerate the main strip (10) and so produce an intermittent movement of the main strip (10) at the application station (SI) .

4) An application unit (4) as claimed in Claim 3, wherein the tensioning device (12) comprises:

two diverting members (13), which are located at opposite ends of the application station (SI), are connected mechanically to each other by a common supporting frame, and are positioned contacting the main strip (10) ; and

a third actuating device (14) which imparts a reciprocating movement to the supporting frame.

5) An application unit (4) as claimed in Claim 4, wherein the third actuating device (14) comprises a connecting rod-crank system for converting rotation to the reciprocating movement imparted to the supporting frame .

6) An application unit (4) as claimed in one of Claims 1 to 5, and comprising:

a supply conveyor (15) , which feeds a secondary strip (16), containing the tear strip (3), to the application conveyor (5) at an input station (S2) of the application path (PI); and

a cutting device (17) connected to the application conveyor (5) to cut the tear strip (3) crosswise off the secondary strip (16) .

7) An application unit (4) as claimed in Claim 6, wherein the cutting device (17) is located downstream from the input station (S2) of the application path (Pi) to cut the tear strip (3) off the secondary strip (16) after the tear strip (3) is engaged by the suction seat (6) .

8) An application unit (4) as claimed in Claim 6 or 7, wherein the cutting device (17) comprises:

at least one heated wire (23) , which cuts the secondary strip (16) crosswise; and

a third actuating device (24), which moves the heated wire (23) with respect to the secondary strip (16).

9) An application unit (4) as claimed in Claim 8, wherein the third actuating device (24) comprises a first drum (25) mounted to rotate about a first central axis (26) of rotation.

10) An application unit (4) as claimed in Claim 8 or 9, wherein the third actuating device (24) is connected mechanically to the application conveyor (5) to move the heated wire (23) together with the application conveyor (5) .

11) An application unit (4) as claimed in one of Claims 1 to 10, wherein, at the application station

(SI), the first actuating device (9) imparts to the suction seat (6) the application movement perpendicular to the application path (PI), to bring the tear strip (3) into contact with, and so apply the tear strip (3) to, the sheet (2) of wrapping material.

12) An application unit (4) as claimed in one of Claims 1 to 11, wherein the application conveyor (5) comprises a second drum (18) mounted to rotate about a second central axis (19) of rotation, and which is fitted peripherally with a head (20) supporting the suction seat (6) .

13) An application unit (4) as claimed in Claim 12, wherein the head (20) is mounted to move radially on the second drum (18) ; and

the first actuating device (9) moves the head (20) radially to impart the application movement to the suction seat ( 6) .

14) An application unit '(4) as claimed in Claim 13, wherein the first actuating device (9) comprises:

an elastic member (21), which pushes the head (20) radially towards the second central axis (19) of rotation; and

a pusher (22) housed centrally in a fixed position inside the second drum (18) to push the head (20) radially and in opposition to the elastic member (21) when the head (20) is located at the application station (SI) .

15) An application unit (4) as claimed in Claim 14, wherein the elastic member (21) is a spring, which is compressed when the head (20) is pushed radially by the pusher (22) .

16) A method of applying to a sheet (2) of wrapping material an inclined tear strip (3) by which to tear off the sheet (2) of wrapping material (2) , and which extends the full width of the sheet (2) of wrapping material; the method comprising the steps of:

moving a suction seat (6), designed to retain the tear strip (3), along an application path (PI) by means of an application conveyor (5) ;

applying the tear strip (3) , retained by the suction seat (^'6) on the application conveyor (5), to the sheet (2) of wrapping material at an application station (SI) located along the application path (PI); and

feeding the sheet (2) of wrapping material, by means of a feed conveyor (8), along a feed path (P2) and through the application station (SI) , where the sheet (2) of wrapping material receives the tear strip (3) ; at the application station (SI) , the application path (PI) not being parallel to the feed path (P2) , but forming an acute angle with the feed path (P2);

the method being characterized in that:

the application conveyor (5) is separate from and independent of the feed conveyor (8); and

at the application station (SI) , a first actuating device (9) imparts an application movement, which is a relative movement between the suction seat (6) and the feed conveyor (8) and perpendicular to the application path (Pi), to bring the tear strip (3) into contact with, and . so apply the tear strip (3) to, the sheet of wrapping material.