WO2023248064A1

WO2023248064A1 - Roller for dividing a web into a plurality of strips suitable for making an article of the tobacco industry

Info

Publication number: WO2023248064A1
Application number: PCT/IB2023/056155
Authority: WO
Inventors: Nicola Baldanza; Marco Esposti
Original assignee: G.D S.P.A.
Priority date: 2022-06-20
Filing date: 2023-06-14
Publication date: 2023-12-28

Abstract

A roller (100) for dividing a web (200) into a plurality of strips (201) suitable for making an article of the tobacco industry comprises a plurality of circular blades (101), provided with respective peripheral cutting edges lying on a common surface. The blades (101) are configured to cut a web (200) into a plurality of strips (201). Each blade (101) has at least one respective indentation (102) defining a reduced-cutting or no-cutting zone such as to create a respective connecting bridge (202) for connecting the respective strip (201) to an adjacent strip (201). The indentations (102) are disposed along a break profile (P) defining a respective distribution of connecting bridges (202) between the strips (201) and comprising two helical portions (P1, P2) converging towards each other along a circumferential direction of the roller (100). The two helical portions (P1, P2) are disposed on adjacent peripheral portions of the peripheral surface of the roller (100).

Description

ROLLER FOR DIVIDING A WEB INTO A PLURALITY OF STRIPS

SUITABLE FOR MAKING AN ARTICLE OF THE TOBACCO INDUSTRY

Technical field

This invention relates to a roller for dividing a web into a plurality of strips suitable for making an article of the tobacco industry.

In particular, the articles referred to herein are articles made from a web of material for the tobacco industry such as, for example: tobacco-based material (reconstituted, pre-treated, homogenized or cast-leaf tobacco), filter paper material or PLA. art

In prior art systems, a web of material for the tobacco industry is cut longitudinally into thin strips which are then gathered and wrapped in a web of paper to form a continuous rod.

During this process, the step of gathering the strips following the step of cutting them may be difficult, often on account of jams and interruptions of the production process.

It has also been observed that high processing speeds, and/or possible local non-uniformity in the structure of the material, and/or possible cutting imprecision may cause one or more of the strips to tear, in turn causing the next part of the strip to fall out. As a result, the machine must be stopped and the strip restored manually, which translates as lower productivity and increased costs.

To overcome this drawback, prior art rollers may be provided with a plurality of cutting blades, each having an indentation or recess constituting a break in the cutting edge of the blade so it does not cut the web at the point where the break is.

In this situation, the flat web is divided into strips which are joined to each other by connecting bridges made by the breaks in the blades. In particular, the connecting bridges between the different strips are the result of the breaks in the cutting edges of the blades, created by the presence of the indentations.

A roller of the above kind is described, for example, in document W02020/048907, in which the indentations on the cutting edges of the blades are distributed along a helix lying on a cylindrical mantle of the roller and whose axis coincides with the axis of the roller.

A similar solution is known from document EP3469922 in the name of the present Applicant, in which a roller with suitable cutting edge break zones cuts a web into strips connected to each other by bridges, where the bridges are distributed in different ways, including a distribution along a segment that is inclined to the direction of extension of the strips.

This distribution, asymmetrical relative to a longitudinal centre line, can result in vibrations on the web which reduce the stability of the web itself, hence having a negative effect on the process.

Other solutions known from document EP3469922 in the name of the present Applicant, comprise rollers with cutting edge break zones which cut a web into strips connected to each other by bridges, where the bridges are distributed along a straight line orthogonal to the direction of extension of the strips.

This distribution of the connecting bridges produces a semi-product that is symmetrical but extremely unstable in the section between one line of bridges and another. This instability translates as a higher probability of the semi-product breaking or being damaged during subsequent processes.

Aim of the invention

The technical purpose of this invention is therefore to provide a roller for dividing a web into a plurality of strips suitable for making an article of the tobacco industry and capable of overcoming the above-mentioned disadvantages of the prior art. This invention therefore has for an aim to provide a roller for dividing a web into a plurality of strips suitable for making an article of the tobacco industry and capable of working in a balanced and mechanically reliable way; in other words, a roller for dividing a web into a plurality of strips capable of minimizing the induced vibrations on the material.

The technical purpose and aim specified are substantially achieved by a roller for dividing a web into a plurality of strips suitable for making an article of the tobacco industry, comprising the technical features set out in claim 1 and/or in one or more of the claims dependent thereon.

This invention also relates to a method for making strips of the tobacco industry from a web, according to claim 10 and a corresponding semiproduct comprising the technical features set out in claim 11 and/or in one or more of the claims dependent thereon.

Brief description of the drawings

Further features and advantages of this invention are more apparent in the exemplary, hence non-limiting, description of an embodiment of a roller for dividing a web into a plurality of strips suitable for making an article of the tobacco industry in accordance with the invention.

The description is set out below with reference to the accompanying drawings which are provided solely for purposes of illustration without restricting the scope of the invention and in which:

- Figure 1 shows a perspective view of a roller according to this invention, for dividing a web into a plurality of strips suitable for making an article of the tobacco industry;

- Figure 2A shows a semi-product of the tobacco industry obtained from a web processed using a roller of this invention;

- Figure 2B shows a detail from Figure 2A;

- Figure 3 shows a view of the cylindrical surface of the roller of Figure 1 , linearized on a flat surface. Detailed description of preferred embodiments of the invention

With reference to the accompanying drawings, the numeral 100 denotes a roller for dividing a web 200 into a plurality of strips 201 suitable for making an article of the tobacco industry. Preferably, the web 200 is flat.

The web 200 referred to herein is made, for example, from at least one of the following materials: reconstituted, pre-treated, homogenized or cast-leaf tobacco, filter paper material or PLA.

According to an aspect of this invention, the roller 100 is rotatable, that is to say, it turns, about an axis of rotation X and comprises a plurality of blades 101 , preferably circular, disposed in succession along the axis of rotation X. With reference to Figure 1 , the blades 101 are alternated with respective grooves. The blades 101 may be independent and packed axially together, or mounted on a common shaft, or they may be made as a single roller or monolithic mantle.

The blades 101 are provided with respective peripheral cutting edges lying on a peripheral surface, preferably cylindrical, and are configured to cut a web 200 into a plurality of parallel strips 201 .

In other words, in the embodiment illustrated in Figure 1 , the blades 101 are disposed circumferentially on the (virtual) cylindrical outside surface of the roller 100 so that as the flat web 200 advances, it is cut longitudinally by the rotating cutting edges to obtain the strips 201 .

In a cross section transverse to the axis of rotation X, the blades 101 may have a pointed shape, for example V-shaped (suitable for making a cut in conjunction with a counter-roller which may be smooth or provided with crests and grooves), or it may have a substantially rectangular shape (suitable for making a cut by interpenetrating a counter-roller having the same shape).

As shown in Figure 1 , each blade 101 has at least one respective indentation 102 defining a reduced-cutting or no-cutting zone such as to create a respective connecting bridge 202 for connecting the respective strip 201 to an adjacent strip 201 .

In other words, the indentations 102 define a break in the continuity of the peripheral cutting edge of the blade 101 so that the cutting edge is unable to cut the web 200 at that point. In this situation, the portion of web 200 under the indentation 101 is not cut and forms a connecting portion between one strip 201 and the next.

In the embodiment illustrated, the indentations 102 have an arcuate shape. Alternatively, the indentations 102 might have any shape suitable for interrupting the cutting action of the respective blade 101 on the flat web 200 at that point.

As shown in Figures 1 and 3, the indentations 102 of the blades 101 are disposed on the periphery of the roller 100 along a break profile P lying on the (cylindrical) peripheral surface and defining a respective distribution of connecting bridges 202 between the strips 201 after cutting.

More in detail, according to the invention, the break profile P comprises two helical portions P1 , P2 converging towards each other along a circumferential direction of the roller 100. In the context of this invention, by "helical" is meant a profile winding around the axis of the roller 100 along the axis itself, preferably (but not necessarily) at a constant angle, that is to say defining a straight line if linearized in a plane. The invention, therefore, can also be applied in an equivalent manner to profiles whose shape is not exactly helical as defined above but which extend continuously around the axis of the roller 100 and along the axis itself.

The helical portions P1 , P2 converge along the circumferential direction of the roller 100 so that, on the strips 201 obtained by dividing the web 200, the connecting bridges 202 are disposed along a profile that converges along the feed direction of the strips 201 themselves.

In other words, the two helical profiles P1 , P2 of the break profile extend around the cylindrical surface of the roller 100 until they converge on each other, as described below. The helical portions P1 , P2 are disposed on adjacent (preferably cylindrical) peripheral portions of the (preferably cylindrical) peripheral surface. In particular, the helical portions P1 , P2 are disposed on peripheral portions which are juxtaposed with each other along the axis of rotation X.

Preferably, the helical portions P1 , P2 are also substantially symmetrical about a transverse plane of the roller 100. Preferably, the transverse plane of the roller 100 is a midplane that is perpendicular to the axis of rotation X and divides the peripheral surface into the first and the second peripheral portion.

This aspect is particularly advantageous in that it allows distributing in a more balanced manner the stresses on the web on account of the interrupted cutting action.

In the preferred embodiment, the two helical portions P1 , P2 extend up to respective axial ends of the roller 100 so they extend right across the full width of the roller 100 (by width is meant the dimension of the roller 100 measured parallel to the axis of rotation X).

This aspect is particularly advantageous in that it allows making connecting bridges 202 for webs 200 whose maximum width is equal to the width (measured along the axis of rotation X) of the roller 100.

In use, the web 200 (preferably flat) is made to slide along the feed direction against the roller 100 being driven in rotation about the axis of rotation X. In this situation, each blade 101 applies on the continuous web 200 a cutting action such as to cause the strips 201 to be separated along the extension of the blade 101 itself except for the zones where the indentations 102 are located. In effect, in this situation, each indentation 102 interrupts the cutting action of the blade 101 so that the portion of web 200 is not cut and, instead, forms the connecting bridge 202.

According to an aspect of the invention, as shown in Figure 1 , the indentations 102 are distributed alternately on one and the other of the two adjacent cylindrical portions of the roller 100 along the circumferential direction of the roller 100. In this situation, each generatrix of the cylindrical surface intersects only one indentation 102.

With reference to Figure 3, the distribution of the indentations 102 located on the first of the two cylindrical portions is symmetrical but staggered along a direction perpendicular to the axis of rotation X relative to the indentations 102 located on the second of the two cylindrical portions. In this situation, a generatrix of the peripheral surface always meets at least one indentation 102, in particular, only one indentation 102.

In other words, proceeding in a circumferential direction of the roller 100 and in particular along a circumferential centre line, the indentations 102 are alternated on one side and the other and follow each other in such a way that a generic generatrix of the peripheral surface intersects only one indentation 102.

In the preferred embodiment, the indentations 102 are distributed according to a wedge-, or cusp- or arrow-shaped distribution.

In other words, the indentations 102 are distributed along a first branch, lying on the first of the two cylindrical portions, and along a second branch, lying on the second of the two cylindrical portions. The first and the second branch converge on each other to form a sort of triangle without a base or a sort of arrow tip pointing in the feed direction of the flat web 200.

In the preferred embodiment, the roller 100 comprises two or more break profiles P axially spaced from each other along the circumferential direction of the roller 100.

In particular, the break profiles P are identical. For example, as shown in Figure 3, the roller 100 comprises a first and a second break profile P, each extending angularly through 180° and the indentations 102 are distributed according to a wedge-, or cusp- or arrow-shaped distribution.

According to an aspect of this invention, a front portion of the first break profile P is aligned with a rear portion of the second break profile P adjacent to the first break profile P (Figure 3). In this situation, considering an axial generatrix of the roller 100, there is always at least one indentation 102, preferably only one indentation 102, that intersects that generatrix.

Advantageously, providing two or more break profiles P following one another in succession allows making the indentations 102 more closely packed.

This invention also has for an object a method for making strips 201 of the tobacco industry from a web 200 (preferably a flat web).

The method is implemented by a first and a second roller 100, rotatable about respective parallel axes and defining between them a transit zone for a web 200 from which the strips 201 are to be made.

More in detail, at least the first roller 100 is made according to what is described above and as shown in Figure 1 .

In a possible embodiment, the second roller, instead, has a substantially smooth outside surface.

Alternatively, the second roller 100 is also made according to what is described above and as shown in Figure 1 , acting in conjunction with the first roller 100 to make the strips 201. In this situation, the first and the second roller 100 are meshed together in such a way that one blade 101 of the first roller 100 is at least partly inserted into a groove of the second roller 100, and vice versa. Furthermore, the first and the second roller 100 are synchronized in rotation in such a way that when an indentation 102 of the first roller 100 is in contact with the web 200 from which the strips 201 are to be made, an indentation 102 of the second roller 100 is also in contact with it. In this situation, the distance between the two indentations 102 acting on the web 200 is greater than or equal to a thickness of the web 200.

Alternatively, the first and the second roller 100 might be meshed together in such a way that when an indentation 102 of the first roller 100 is in contact with the web 200, an unbroken portion of the cutting edge of the second rollers 100 is in contact with the web 200.

The method also comprises a step of feeding a web 200 of the tobacco industry continuously between the first and the second roller 100 so that the web leaving the rollers 100 is divided into parallel strips 201 joined to each other by connecting bridges 202.

In particular, as the web 200 passes between the rollers 100, the rotation of the rollers 100 causes each blade 101 to come progressively into contact with the web 200, applying a cutting action thereon except on the points where the indentations 102 are made. In effect, when the blade 101 comes into contact with the web 200 in the zone of an indentation 102, the cutting action is interrupted so as to leave a strip of web 200, that is to say, a connecting bridge 202 between one strip 201 and the next.

The connecting bridges 202 are distributed according to a connecting profile C defined by two connecting lines C1 , C2 which are laterally juxtaposed and convergent along the feed direction of the strips 201 .

More in detail, as shown in Figure 2, the distribution of the connecting bridges 202 on the web 200 is the same as the distribution of the indentations 102 of the rollers 100.

In effect, the two connecting lines C1 , C2 are substantially the same in shape as the break profile P defined on the roller 100 by the distribution of the indentations 102, linearized in a plane (a constant-angle, helical line linearized in a plane corresponds to a straight line segment).

In the preferred embodiment, the distribution of the connecting bridges 202 on the web 200 has the shape of a wedge, an arrow or a cusp oriented along a feed direction of the flat web 200.

This invention also has for an object a continuous semi-product S of the tobacco industry, comprising a plurality of juxtaposed strips 201 joined to each other by a succession of connecting bridges 202.

The connecting bridges 202 are distributed along a succession of consecutive connecting profiles C along the main direction of extension of the continuous semi-product S.

Each connecting profile C is defined by two connecting lines C1 , C2 which are laterally juxtaposed (that is placed side by side in a direction orthogonal to the main direction of extension of the semi-product S) and convergent along the main direction of extension of the continuous semi-product S.

In particular, as shown in Figures 2A and 2B, the connecting bridges 202 of each connecting profile C are distributed alternately on a first and a second longitudinal band of the continuous semi-product S which extends along the main direction of extension of the continuous semi-product S itself. In particular, by first and second longitudinal band are meant two portions of the continuous semi-product S which extend parallel to the main direction of extension of the continuous semi-product S itself and are juxtaposed with each other. In this situation, a generic straight line perpendicular to the main direction of extension of the continuous semi-product S intersects only one connecting bridge 202, in the same way as described with reference to the distribution of the indentations 102 on the roller 100.

According to an aspect of this invention, the first and the second longitudinal band of the semi-product are substantially symmetrical about a longitudinal plane of the continuous semi-product S itself, preferably a longitudinal midplane.

In the preferred embodiment, the connecting bridges 202 of each connecting profile C are distributed according to a wedge-, or arrow- or cusp- or Vee-shaped distribution.

According to an aspect of the invention, a frontmost portion of a first connecting profile C is aligned with a rear portion of a second connecting profile C adjacent to the first.

In the preferred embodiment, the connecting bridges 202 are distributed along a first and a second succession of consecutive connecting profiles C. In this situation, the connecting bridges 202 defining the rear portion of the first connecting profile C are aligned with the connecting bridges 202 defining the front portion of the second connecting profile C.

Preferably, each connecting profile C extends across the full width of the continuous semi-product S, thus ensuring that the end strips 201 of the continuous semi-product S are joined to the strips 201 adjacent to them by at least one connecting bridge 202.

In a variant of the invention, not illustrated, the indentations 102 are disposed perfectly symmetrically about the transverse midplane of the roller 100; thus, they do not extend alternately on one or the other (cylindrical) peripheral portion along the circumferential extension but are disposed symmetrically on both the peripheral portions (with the exception of the first indentation defining the tip of the arrow or cusp), thus doubling the number of indentations 102 (and of connecting bridges 202). Thus, the indentations 102 along the break profile P are distributed according to two identical,, symmetrical helixes. The same applies to the distribution of the connecting bridges 202 on the continuous semi-product S.

The invention achieves the preset aims and overcomes the drawbacks of the prior art.

In particular, this invention provides a roller 100 on which, thanks to the shape of the break profile P, the vibrations transmitted to the web during processing are very limited or absent altogether and, consequently, the web remains very stable while it is being processed and the process as a while is highly reliable.

Claims

1. A roller (100) for dividing a web (200) into a plurality of strips (201 ) suitable for making an article of the tobacco industry, the roller (100) being rotatable about an axis of rotation (X) and comprising a plurality of blades (101 ), preferably circular, disposed in succession along the axis of rotation (X), the blades (101 ) being provided with respective peripheral cutting edges lying in a peripheral surface, preferably cylindrical, and being configured to cut a web (200) into a plurality of strips (201 ), each blade (101 ) having at least one respective indentation (102) defining a reduced-cutting or no-cutting zone such as to create a respective connecting bridge (202) for connecting the respective strip (201 ) to an adjacent strip (201 ), the indentations (102) in the blades (101 ) being disposed along a break profile (P) defining a respective distribution of connecting bridges (202) between the strips (201 ), the break profile (P) lying on the peripheral surface, the roller being characterized in that the break profile (P) comprises two helical portions (P1 , P2) converging towards each other along a circumferential direction of the roller (100), the two helical portions (P1 , P2) being disposed on a first and a second peripheral portion, adjacent to each other, preferably adjacent along the axis of rotation (X) of the peripheral surface.

2. The roller according to claim 1 , wherein the indentations (102) are distributed alternately on one and the other, first and second peripheral portion along the circumferential direction of the roller (100).

3. The roller according to claim 2, wherein each generatrix of the peripheral surface intersects only one indentation (102).

4. The roller according to any one of the preceding claims, wherein the indentations (102) are distributed according to a wedge-, or cusp- or arrowshaped distribution.

5. The roller according to any one of the preceding claims, comprising two or more break profiles (P), in particular identical to each other, spaced along the circumferential direction of the roller (100).

6. The roller according to claim 5, wherein a front portion of a first break profile (P) is aligned with a rear portion of a second break profile (P) adjacent to the first break profile (P) along the circumferential direction of the roller (100).

7. The roller according to any one of the preceding claims, wherein the helical portions (P1 , P2) converge along the circumferential direction of the roller (100) so that, on the strips (201 ) obtained by dividing the web (200), the connecting bridges (202) are disposed along a profile that converges along the feed direction of the strips (201 ) themselves.

8. The roller according to any one of the preceding claims, wherein the helical portions (P1 , P2) are symmetrical about a transverse plane of the roller (100), preferably a midplane; the transverse plane dividing the peripheral surface into the first and the second peripheral portion.

9. The roller according to any one of the preceding claims, wherein the two helical portions (P1 , P2) extend up to respective axial ends of the roller (100) so they extend right across the full width of the roller (100).

10. A method for making strips (201 ) of the tobacco industry from a web (200), comprising the following steps:

- setting a first and a second roller (100) in rotation about respective parallel axes, wherein the first and the second roller (100) define between them a transit zone through which a continuous web (200) passes, and wherein at least the first roller (100) is made according to one or more of the preceding claims;

- feeding a web (200) of the tobacco industry continuously between the first and the second roller (100) so that the web (200) leaving the rollers (100) is divided into parallel strips (201 ) joined to each other by connecting bridges (202), wherein the connecting bridges (202) are distributed according to a connecting profile (C) defined by two connecting lines (C1 , C2) which are laterally juxtaposed and convergent along the feed direction of the strips (201 ).

11. A continuous semi-product (S) of the tobacco industry, comprising a plurality of juxtaposed strips (201 ) joined to each other by a succession of connecting bridges (202), wherein the connecting bridges (202) are distributed along a succession of consecutive connecting profiles (C) along the main direction of extension of the continuous semi-product (S), and wherein each connecting profile (C) is defined by two connecting lines (C1 , C2) which are laterally juxtaposed and convergent along the main direction of extension of the continuous semi-product (S).

12. The continuous semi-product (S) according to claim 11, wherein the connecting bridges (202) of each connecting profile (C) are distributed alternately on a first and a second longitudinal band of the continuous semiproduct (S) which extends along the main direction of extension of the continuous semi-product (S).

13. The continuous semi-product (S) according to claim 11 or 12, wherein the connecting bridges (202) of each connecting profile (C) are distributed according to a wedge-, or cusp- or arrow-shaped distribution.

14. The continuous semi-product (S) according to any one of claims 11 to

13, wherein a front portion of a first connecting profile (C) is aligned with a rear portion of a second connecting profile (C) adjacent to the first connecting profile (C) along the main direction of extension of the continuous semi-product (S).

15. The continuous semi-product (S) according to any one of claims 11 to

14, wherein each connecting profile (C) extends across the full width of the continuous semi-product (S).