GUIDE ROLLER FOR A WEB OF WRAPPING MATERIAL OF THE TOBACCO INDUSTRY.

Technical field

This invention relates to a guide roller for a web of wrapping material of the tobacco industry.

This invention also relates to a guide assembly for two or more webs of wrapping material of the tobacco industry and to a method for guiding a web of wrapping material of the tobacco industry.

Background art

Known in the prior art to date are guide rollers comprising a first and a second side plate having, interposed between them, a fixed central portion in the form of a roller or cylinder. In this situation, the fixed central portion defines a movement guide which the web of wrapping material is made to slide in contact with.

Disadvantageously, the sliding contact between the web of wrapping material and the fixed central portion produces local heating on the fixed central portion which may rapidly become so hot as to alter the shape of the web or even tear the web.

To overcome this problem, some guide rollers known in the prior art are provided with a plurality of holes through which respective air flows are emitted. In this situation, an air cushion is created between the web of wrapping material and the fixed central portion, keeping the web of wrapping material in a suspended condition which prevents sliding contact.

Disadvantageously, this technical feature also has inherent drawbacks in that it is unsuitable for use with a web of wrapping material that is porous. In effect, in this situation, the air flows emitted through the holes pass through the web of wrapping material, thus reducing the effect of the air cushion and leading to the same problems as those described above, where there is no air cushion.

To overcome this problem and to make the guide roller suitable also for webs of more porous wrapping materials, some prior art guide rollers are provided with a central portion which is made to rotate about its longitudinal axis of extension together with the first and the second side plate. In other words, in this situation, the entire guide roller rotates about its longitudinal axis of extension.

Although such a solution prevents the guide roller from overheating and reduces web wear, it too is disadvantageous in that the wrapping material, as it advances, tends to move "off track", sliding over the first or the second side plate, making web feed as a whole more difficult and requiring frequent maintenance operations.

Summary of the disclosure

The technical purpose of this invention, therefore, is to provide a guide roller, a guide assembly and a method for guiding a web of wrapping material for rod sections of the tobacco industry, capable of overcoming the above mentioned disadvantages of the prior art.

The aim of this invention is, therefore, to provide a guide roller that prevents heating of the device itself and does not damage the web of wrapping material being processed.

Another aim of this invention is to provide a method for guiding a web of wrapping material that is efficient and reliable and suitable for all types of wrapping materials.

The technical purpose indicated and the aims specified are substantially achieved by a guide roller, a guide assembly and a method for guiding such a web of wrapping material, comprising the technical features described in claims 1 , 11 and 13, respectively, 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 guide roller for a web of wrapping material of the tobacco industry, of a guide assembly for the web, and of a method for guiding such a web 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 guide assembly of this invention, for a web of wrapping material of the tobacco industry;

- Figure 2 shows a cross sectional view of the guide assembly shown in Figure 1 ;

- Figure 3 shows a side view of the guide assembly shown in Figure 1 ;

- Figure 4 shows a cross sectional view of a guide roller of the guide assembly of Figure 1 .

Detailed description of preferred embodiments of the invention

With reference to the accompanying drawings, the numeral 300 denotes a guide assembly for two or more webs of wrapping material of the tobacco industry.

The guide assembly 300 comprises a supporting pin 105 extending along a longitudinal axis X and on which there are coaxially mounted two or more guide rollers 100, 200 configured to guide the feed motion of respective webs of wrapping material.

According to an aspect of this disclosure, the supporting pin 105 is adapted to be mounted in stationary, cantilevered manner on a preferably vertical supporting wall (not illustrated).

The supporting pin 105 may be made in the form of a solid shaft extending along the longitudinal axis X.

In a possible embodiment, the supporting pin 105, at one end of it suitable for being operatively directed towards the supporting wall, may be provided with an anti-rotation element 105' configured to prevent the supporting pin 105 from rotating about the longitudinal axis X when the supporting pin 105 is mounted on the supporting wall. The anti-rotation element 105' may be advantageously mounted on a flanged portion, in particular, a disc shaped portion, defining a large-diameter zone.

As shown in the accompanying drawings, the guide rollers 100, 200 are mounted coaxially on the supporting pin 105 at different axial portions of the supporting pin 105.

In the embodiment illustrated by way of non-limiting example, a first and a second guide roller 100, 200 are mounted on the supporting pin 105 in the proximity of the ends thereof.

In different embodiments not illustrated, the guide assembly 300 might comprise more than two guide rollers 100, 200 mounted coaxially on the supporting pin 105.

In this situation, the guide rollers 100, 200 occupy axial portions which are equispaced from each other along the supporting pin 105 itself.

Alternatively, the guide rollers 100, 200 might occupy axial portions which are not equispaced from each other along the supporting pin 105.

As shown in detail in Figure 2, each guide roller 100, 200 comprises a central portion 101 configured to define a partial wrapping surface for the web of wrapping material.

In other words, the central portion 101 defines a supporting and sliding contact surface on which the web of wrapping material runs as it advances, for example, along a feed line of the web of wrapping material itself.

In the embodiment illustrated, the central portion 101 is made in the form of a hollow tube whose outside surface defines the partial wrapping surface for the web of wrapping material.

According to an aspect of this disclosure, the central portion 101 comprises at least one circumferential recess 107 in the form of a zone that is indented with respect to the rest of the cylindrical outside surface of the central portion 101. The recess 107 is configured to receive residues of adhesive substance and/or waste particles from the web of wrapping material.

As shown in the accompanying drawings, the recess 107 is made on the outside surface of the central portion 101 at a position matching at least one line of glue on the web of wrapping material.

In the preferred embodiment, the central portion 101 of each guide roller 100, 200 comprises two recesses 107, although, depending on requirements, there may be any number of recesses 107 and/or they may be axially distributed in any way. According to specific requirements, the central portion 101 might not have any recesses 107 at all.

In a possible embodiment, the two recesses 107 have the same width along the longitudinal axis X. This aspect is advantageous when the web of wrapping material has two lines of glue which have the same width.

Alternatively, the recesses 107 of each guide roller 100, 200 may differ in width. This aspect is advantageous when the web of wrapping material has two lines of glue which have different widths.

According to an aspect of this disclosure, each guide roller 100, 200 also comprises a scraping member 108 operatively associated with the at least one recess 107 and configured to detach and remove adhesive substance residues and/or waste particles from the recess 107.

In the embodiment shown in the accompanying drawings, the scraping member 108 is made in the form of a comb having a plurality of protrusions configured to slide in contact with the central portion 101 .

Looking in more detail, in the embodiment illustrated, the scraping member 108 comprises a first set of protrusions 108a alternated with a second set of protrusions 108b.

The protrusions of the first set 108a have a width (measured along the longitudinal axis X) which makes them suitable for insertion into a respective recess 107 so as to remove all the residue therefrom. The protrusions of the second set 108b have a width (measured along the longitudinal axis X) which is greater than that of the protrusions of the first set 108a. In this situation, while the protrusions of the first set 108a clean the recesses 107 and are at least partly inserted therein, the protrusions of the second set 108b are adapted for scraping the parts of the outside surface of the central portion 101 not occupied by the recesses 107 (Figure 2).

Advantageously, the scraping members 108 allow all the accumulated glue residue to be removed continuously, quickly and easily from the recesses 107 and/or from the outside surface of the central portion 101 so as to prevent such residue from spoiling the end quality of the web of wrapping material.

In an embodiment not illustrated, the scraping member 108 comprises one or more first protrusions 108a for engaging respective recesses 107, while the second protrusions 108b are omitted.

According to an aspect of this disclosure, each guide roller 100, 200 also comprises a first and a second lateral portion 102a, 102b disposed at the sides of the central portion 101 and forming respective guide shoulders (larger in diameter than the central portion 101 ) for lateral edges of the web of wrapping material.

In effect, as shown in Figure 2, in conjunction with the central portion 101 , the first and second lateral portions 102a, 102b define an annular niche N in which the web of wrapping material is slidably received and guided.

In other words, during its sliding feed motion in contact with the guide roller 100, the web of wrapping material is supported by the central portion 101 , while its lateral edges slide in contact with, or at a reduced distance from, the first and the second lateral portion 102a, 102b, respectively, so as to be suitably guided at the sides.

With reference to the accompanying drawings, in particular Figure 2, the guide rollers 100 are mounted on the central pin 105 mirror symmetrically, in particular in such a way that their respective second lateral portions 102b face each other along the longitudinal axis X, while their respective first lateral portions 102a face towards the ends of the supporting pin 105. Looking in more detail, the first lateral portions 102a of the guide rollers 100 are engaged with respective caps 109 which are connected to corresponding ends of the supporting pin 105 by elastic elements 110, for example, springs.

As shown in Figure 2, in conjunction with the first lateral portions 102a, the caps 109 define chambers for accommodating the elastic elements 110 which are configured to facilitate mounting the guide rollers 100, 200 on the supporting pin 105.

According to an aspect of this disclosure,, the first and second lateral portions 102a, 102b are rotationally fixed (that is, they do not rotate) while the central portion 101 is rotatable about its longitudinal axis X relative to the first and second lateral portions 102a, 102b.

Preferably, the central portion 101 is rotatable idly about the longitudinal axis X.

In this situation, the central portion 101 is free to rotate about the supporting pin 105, while the first and second lateral portions 102a, 102b are fixedly attached to the supporting pin 105 so that they cannot rotate.

In use, therefore, as the web of wrapping material advances, the web slides in contact with the central portion 101 , causing it to rotate idly about the longitudinal axis X and, in particular, about the supporting pin 105. In this situation, the web of wrapping material is accompanied in its advancing feed motion by the rotation of the central, portion 101 , while the first and second fixed lateral portions 102a, 102b direct the web by acting as guides for its lateral edges but, since they are fixed, preventing its lateral edges from sliding off-track over them.

Advantageously, allowing the central portion 101 to rotate idly means that the web of wrapping material does not rub against the central portion 101 but is accompanied and supported as it advances, preventing unwanted wear and the risk of tearing the web of wrapping material. Advantageously, allowing the central portion 101 to rotate idly prevents unwanted heating of the guide roller 100, in particular of its central portion 101.

Advantageously, the fact that the first and second lateral portions 102a, 102b are prevented from moving allows preventing the web of wrapping material, as it advances, from slipping out of the annular niche N and sliding over the first and second lateral portions 102a, 102b (with the risk of crumpling or tearing the web of wrapping material itself).

In accordance with what is shown in Figures 2 and 4, each guide roller 100, 200 also comprises a rotationally fixed central support 103.

In a possible embodiment, the central support 103 is made in the form of a hollow tubular element which can be fitted lengthways over the supporting pin 105 and which is smaller in diameter than the central portion 101 of the guide roller 100, 200 so it can be axially inserted into the central portion 101 in order to support the latter.

In effect, as shown in the accompanying drawings, the central portion 101 is entirely and exclusively supported by the central support 103.

In particular, the central portion 101 is mounted on, or fitted over, the central support 103 by means of rolling bearings 104 and preferably has a central zone that is indented, that is to say, reduced in thickness, towards the longitudinal axis X, defining at its axial ends respective abutments for the two rolling bearings 104. The rolling bearings 104 thus define a stable, predetermined axial position for the central portion 101. In particular, gaps of predetermined size are provided between the central portion 101 and the respective lateral portions 102a, 102b so that the central portion 101 can rotate idly about the central support 103 without friction against the lateral portions 102a, 102b.

As shown in the accompanying drawings, the diameter of the central support 103 is smaller than that of the central portion 101 and such as to define, between the central support 103 and the central portion 101 , a space which houses the rolling bearings 104 which are interposed between the central support 103 and the central portion 101 so as to allow the latter to rotate about the central support 103 when the web of wrapping material passes.

According to an aspect of this disclosure, the central support 103 is connected to the lateral portions 102a, 102b to be rotationally integral therewith.

In other words, the central support 103 and the lateral portions 102a, 102b are connected to each other to form a single body that is rotationally fixed around the central pin 105.

In a possible embodiment, not illustrated, the central support 103 is an element that is separate from the first and second lateral portions 102a, 102b. In this situation, the central support 103 has a first end 103a that is stably engaged with the first lateral portion 102a, and a second end 103b, opposite the first end 103a, that is stably engaged with the second lateral portion 102b. In particular, in this embodiment, the first and second lateral portions 102a, 102b are fitted over the respective ends 103a, 103b of the central support 103 and connected to them to form the aforementioned rotationally fixed structure capable of acting as a support about which the central portion 101 is free to rotate idly.

In another embodiment illustrated in the accompanying drawings, on the other hand, the central support 103 is made as one with the first lateral portion 102a.

Looking in more detail, the central support 103 extends along the longitudinal axis X and has a first end 103a that is integral with the first lateral portion 102a, and a second, free end 103b over which the second lateral portion 102b is reversibly fitted so that the latter is attached as one with the central support 103 itself.

As shown in the accompanying drawings, the second lateral portion 102b is removably connected to the central support 103 by a fixing means 111 which is embodied, for example, in the form of a grub screw operable to be inserted into a suitable hole made in the second end 103b of the central support 103. In this situation, as shown in Figures 2 and 4, the grub screw is inserted into the hole made in the second lateral portion 102b so as to make the second lateral portion 102b integral with the central support 103.

In other words, the fixing means 111 allows joining the central support 103 and the second lateral portion 102b together as one so as to define a rotationally fixed structure on which the central portion 101 is free to rotate when the web of wrapping material passes.

In a variant embodiment not illustrated, the second lateral portion 102b may be defined by a threaded ring which can be screwed onto an end portion of the central support 103 and preferably rotationally locked by a grub screw so as to join the central support 103 and the second lateral portion 102b together as one to define a rotationally fixed structure.

According to an aspect of this disclosure, the axial position of the guide rollers 100 along the supporting pin 105 is adjustable so as to make the guide assembly 300 versatile and adaptable to every need.

In effect, as shown in the accompanying drawings, the axial portions of the supporting pin 105 are provided with respective threaded zones 105a, 105b. In this situation, each of the guide rollers 100, 200 is permanently engaged with a corresponding threaded zone 105a, 105b and preferably adjustable independently of the other by rotation relative to the respective threaded zone 105a, 105b.

Thanks to this rotation relative to a corresponding threaded zone 105a, 105b, it is thus possible to adjust the axial position of each guide roller 100, 200 independently along the supporting pin 105.

In other words, each guide roller 100 is engageable with a respective threaded zone 105a, 105b so that rotating it about the longitudinal axis X allows its axial position to be adjusted along the threaded zone 105a, 105b itself.

In the preferred embodiment, the central support 103 of each guide roller 100, 200 is applied in axially adjustable manner to the supporting pin 105. In particular, the threaded zones 105a, 105b are engaged by corresponding threads made on the central support 103 and/or on the first lateral portion 102a to define a lead screw and nut coupling.

In this situation, by operating manually on the central support 103 and/or on the first lateral portion 102a, the axial position of each guide roller 100, 200 is suitably adjusted.

In other words, to vary the axial position of each guide roller 100, 200 along the supporting pin 105, the central support 103 and/or the first lateral portion 102a are rotated about the supporting pin 105 along the threaded zone 105a, 105b so as to allow the central portion 101 and the second lateral portion 102b to be axially displaced.

According to an aspect of this disclosure, to facilitate adjustment of the axial position of the guide rollers 100, 200, the first lateral portion 102a of each guide roller 100, 200 is provided with external knurling 102' to make it easier for a user to grip and operate it. The first lateral portion 102a is preferably between 1 and 6 cm, and more preferably, between 2 and 4 cm, in length along the longitudinal axis X.

With reference to the embodiment illustrated, to adjust the axial position of the guide rollers 100, 200 along the supporting pin 105, in use, an operator grips the external knurling 102' so as to cause the first lateral portion 102a to rotate about the central portion 101. In this situation, since the first lateral portion 102a and the central support 103 are joined together as one, they rotate about the supporting pin 105 along the corresponding threaded zone 105a, 105b until the desired axial position is reached.

To lock the guide rollers 100, 200 at a predetermined axial position after being adjusted as just described, the first lateral portion 102a of each guide roller 100 comprises a respective locking means 106.

In a preferred embodiment, the locking means 106 is embodied in the form of a grub screw insertable in a suitable hole made in the first lateral portion The grub screw is configured to act on the supporting pin 105 and is operable to prevent or allow rotational movement of the first lateral portion 102a relative to the supporting pin 105. More in detail, the grub screw is extracted or retracted from the hole made in the first lateral portion 102a so as to apply or not apply a tightening action on the supporting pin 105 to stop it both sliding and rotating.

Alternatively, the fixing means used for stopping the guide roller 100, 200 along the longitudinal axis X may be defined by the very same grub screw which defines the locking means 111 between the second lateral portion 102b and the central support 103, which thus extends past the inside surface of the central support 103 and reaches the supporting pin 105.

In use, therefore, at least one guide roller 100, 200 is provided for guiding a web of wrapping material of the tobacco industry.

In the embodiment illustrated, a first and a second guide roller 100, 200 are provided in proximity to the ends of the supporting pin 105, which defines respective threaded zones 105a, 105b along which the position of the guide rollers 100, 200 can be adjusted.

Looking in more detail, as shown in the accompanying drawings, the first guide roller 100 (identified as the roller on the right in Figure 2) is fitted over the supporting pin 105 in such a way that its first lateral portion 102a is engaged with the cap 109 placed on the end of the supporting pin 105. In this situation, the second lateral portion 102b is fitted over the supporting pin 105 so as to "pack" the central portion 101 and the first lateral portion 102a closely together. Looking in more detail, the second lateral portion 102b is connected to the end 103b of the central support 103 and is made to slide axially along the central support 103 itself to act as a compacting element.

The second guide roller 200 (identified as the roller on the left in Figure 2) is fitted over the supporting pin 105 in such a way that its second lateral portion 102b confronts the second lateral portion 102b of the first guide roller 100. In this situation, the first lateral portion 102a of the second guide roller 200 is engaged with the cap 109 placed on the other end of the supporting pin 105 so the second guide roller 200 is also "packed" closely together.

Following assembly of the first and the second guide roller 100, 200, a web of wrapping material for each guide roller 100, 200 is fed in such a way as to slide in contact with the central portion 101 and between the lateral portions 102a, 102b of a respective guide roller 100, 200.

In this situation, the central portion 101 is entrained in rotation by the web of wrapping material, while the lateral portions 102a, 102b act as shoulders and guides for the edges of the web of wrapping material.

Preferably, the porosity of the webs of wrapping material is between 6000 and 32000 CU (COREST A Units).

Advantageously, the idle rotational motion of the central portion 101 and the stability of the lateral portions 102a, 102b allow feeding particularly porous webs of wrapping material without the risk of overheating the guide rollers 100, 200 and/or the webs moving off track or tearing.

This invention is also applicable to systems with a single guide roller, hence to single-line machines. In such a situation, the guide roller still comprises the central supporting pin, preferably not hollow, configured to support the guide roller and to allow it to be axially adjusted as described in the foregoing. Alternatively, the supporting pin may be omitted in this case, and the roller assembled by coupling one of the two lateral portions or the central support directly to the vertical wall of the machine.

The invention achieves the preset aims overcoming the drawbacks of the prior art.

In particular, this invention allows guiding webs of wrapping material (including particularly porous webs) without the risk of overheating the guide roller and/or without the risk of the web itself tearing or creasing or moving off track.