GB2155753A - Device for piercing holes in rod- shaped items - Google Patents

Abstract

Device for piercing holes (13) in rod-shaped items (2), particularly cigarettes, on which the said items (2) are housed inside respective recesses mounted so as to turn round their own axes on a conveyor moving crosswise in relation to the said axes and connected integral with focusing lenses (20) each associated with a respective said recess. When the conveyor is operated, each said focussing lens (20) intercepts a pulsating light beam (8) generated by a laser source and a diffuser (11) located between the said laser source and the route travelled along by the said focusing lenses (20), the said beam (8) being focused on the periphery of the respective said cigarette (2) as the latter turns together with its respective recess. <IMAGE>

Description

DESCRIPTION Device for piercing holes in rod-shaped items The present invention relates to a device for piercing holes in rod-shaped items.

The present invention is particularly suitable for producing smoking commodities, especially cigarettes, to which the following description refers solely by way of a non-limiting example.

The cigarette manufacturing industry is known to produce so-called "ventilated" cigarettes, i.e.

cigarettes with a number of holes in the area of the filter for enabling smokers to inhale a certain amount of air together with the smoke, in such a manner as to dilute the smoke intake and reduce both its temperature and content of harmful substances.

The said ventilating holes are known to be formed using piercing devices comprising a laser source, possibly pulsating, and a focusing device designed to direct the laser beam on to the cigarettes as the latter travel along a given route, possibly also turning round their own axes.

On the aforementioned known types of piercing devices, the focusing device is usually assigned a reflecting member designed to direct the focused beams on to the cigarettes in such a manner as to follow the latter as they are moved along.

One of the major drawbacks on piercing devices of the aforementioned type is that the holes so formed are usually irregular in shape and unevenly arranged round the cigarettes. The main reason for this is that the laser source, the focusing device and the associated reflecting member are generally located some distance away from the cigarettes being pierced, the movement of the latter along the said given route being determined by a conveying device supported separately from the respective piercing device. As the piercing device is thus unaffected by the vibration usually imparted on the cigarettes by the said conveying device, the cigarettes being pierced depart unpredictably from what should be a given ideal route.

The aim of the present invention is to provide a laser piercing device designed to overcome the aforementioned drawback.

With this aim in view, the present invention relates to a device for piercing holes in rod-shaped items, particularly cigarettes, the said device comprising a conveyor, a number of moving recesses suported on the said conveyor crosswise in relation to the travelling direction of the same and each designed to house a respective item, a laser source designed to emit a pulsating laser beam, and a focusing device designed to focus the said laser beam successively on to the said moving items, characterised by the fact that it comprises a diffusor located between the said source and the said focusing device; the said focusing device comprising, for each said recess, a focusing lens integral with the said conveyor and travelling with the same along a given route, and a rotating device being supported on the said conveyor for turning each said recess round its own axis.

A non-limiting arrangement of the present invention will now be described with reference to the attached drawings in which: Fig. 1 shows a front view of a piercing device according to the present invention; Fig. 2 shows a view in perspective of a detail in Fig. 1; Fig. 3 shows a section along line Ill-Ill in Fig. 1; Fig. 4 shows a view in perspective, with parts removed for clarity, of a detail in Fig. 3.

Number 1 in Fig. 1 indicates a conveyor or feed roller for cigarettes 2, the said roller 1 forming part of a filter assembling machine numbered as a whole by 3 and comprising, in addition to roller 1, a feed roller 4 and unloading roller 5 turning equally and arranged tangent with two points on the periphery of roller 1.

As shown in Fig. 3, roller 1 forms part of a piercing device indicated as a whole by 6 and comprising a pulsating laser source, indicated as a whole by 7 and designed to emit a laser beam 8 along the axis of a centre hole 9 on a fixed tubular shaft 10 supporting in rotary manner roller 1, a diffuser 11, designed to deflect beam 8 radially outwards and shape it as described in more detail later on, a focusing device 12, turning with roller 1 and designed to focus beam 8 on to cigarettes 2 so as to form on the same a ring of holes 13, and a rotating device 14, designed to turn cigarettes 2 round their axes as they are moved along by roller 1 turning round the axis of shaft 10.

As shown in Fig. 3, hole 9 is closed, on the opposite side to that facing source 7, by a flanged cap 15 a centre portion of which penetrates inside hole 9 and is limited by a 45 mirror surface defining mirror 16. The latter forms part of diffusor 11 and is designed to divert beam 8 radially outwards of shaft 10 through slit 17 which, as shown in Fig. 1, extends round shaft 10 over an arc the aperture of which corresponds, on the periphery of roller 1, with an arc equal to at least three times the spacing of cigarettes 2.

As shown in Fig. 3 and particularly in Fig. 2, diffusor 11 also comprises a first lens 18 consisting, in the specific example shown, of an essentially planocylindrical lens with its axis parallel to that of shaft 10, and a second lens 19 consisting, in the specific example shown, of a essentially planocyclindrical lens with its axis perpendicular to that of shaft 10. Lenses 18 and 19 are both integral with shaft 10 and arranged with the second outside the first in relation to the axis of shaft 10 and facing slit 17 along a centre radial axis of the latter. As shown in Figs. 1 and 2, focusing device 12 comprises a number of focussing lenses 20 supported on and evenly arranged round roller 1 and each associated with a respective recess 21 formed axially on the periphery of roller 1 and designed to house a respective cigarette 2.

According to the specific arrangement shown in Figs. 3 and 4, shaft 10 projects from a side wall 22 on machine 3 and presents, on its free end, an outer flange 23 connected with cap 15 and cooperating along its outer periphery with the inner ring of a first bearing 24 supporting roller 1. The latter comprises an essentially cylindrical bell 25 coaxial with shaft 10 and fitted on to the same with its concave side facing wall 22. Bell 25 presents an end wall 26, having an axial centre hole 27 housing bearing 24, and an essentially cylindrical side wall 28 having an annular groove 29 adjacent to wall 26.

Through an end wall on annular groove 29, are formed holes 30, evenly arranged round the axis of shaft 10, equal in number to recesses 21 and each housing a respective focusing lens 20.

Side wall 28 of bell 25 comprises a smallerdiameter portion 31, adjacent to groove 29, and a wider portion 32 facing wall 22 and blended with portion 31 by means of annular shoulder 33.

From the inner surface of wall 28, two annular flanges 34 and 35 extend radially inwards, the first next to shoulder 33 and the second next to the free end of wall 28 facing wall 22, so as to define a cylindrical hole 36 coaxial with shaft 10 and housing a second bearing 37 supporting roller 1 on shaft 10 itself.

Next to flange 35, side wall 28 presents an outer ring gear 38 engaging with a gear supported in rotary manner on wall 22 and connected to a drive unit (not shown) for turning roller 1 round its own axis as a given constant speed in the opposite direction to rollers 4 and 5. The rotating device 14, shown by way of an example in Figs. 3 and 4, is divided into two groups of gear chains, 40 and 41, associated with respective alternating pairs of recesses 21. In other words, when one of the said pairs of recesses 21 is associated, for example, with one chain 40, the two adjacent pairs of recesses 21 are associated with a chain 41.

Each chain 40 comprises a rocker arm 42, in turn comprising a hinge pin 43 with its axis parallel to that of bell 25. Each pin 43 engages, in rotary manner, a respective through hole 44 formed through flange 34, and is connected integral, with its end facing wall 26, to a first arm 45 perpendicular with pin 43 itself and connected at its free end to a tappet roller 46 moving along cam 47. The latter is integral with shaft 10 and presents a working surface formed round the axis of shaft 10 itself.

On the end facing wall 22, each pin 43 is conected integral to a second arm consisting of a sector gear 48 extending in a plane perpendicular to the axis of shaft 10 and integral with a tappet roller 49 moving along cam 50. The latter is integral with shaft 10 and presents a working surface formed round the axis of shaft 10 itself. Each sector gear 48 engages with two gears 51, each fitted on to a respective shaft 52 parallel with shaft 10 and mounted in rotary manner, at one end, through hole 53 in bell 25 next to shoulder 33 and, at the other end, through hole 54 in flange 35.

The end of each shaft 52 facing wall 26 comes out of bell 25 through respective hole 53 and is connected integral with an axial appendix 55 extending outwards or portion 31 on wall 28 and having an axial groove defining a respective recess 21. The latter has an exhaust groove 56 running along it and communicating with a duct 57 extending along respective shaft 52 and, in turn, communicating, on the side facing wall 22, with an exhaust groove 58 communicating with an exhaust source not shown.

Groove 58 is formed on the front surface of an annular distribution plate 59 and extends round the axis of shaft 10 over essentially the entire arc between the points of tangency of rollers 4 and 5 with roller 1.

Distribution plate 59 is mounted in axially sliding manner on a cylindrical bush 60 coaxial with shaft 10 and integral with wall 22, and is held flexibly contacting the end of shafts 52 by means of a number of springs 61. Each chain 41 comprises a number of rocker arms 62, each comprising a hinge pin 63 mounted in rotary manner through a respective through hole 64 formed in flange 35.

Rocker arms 62 are esentially identical to rocker arms 42 and each comprise a first arm 65, similar to arms 45 and having a tappet roller 66, and a sector gear 67 similar to sector gears 48 and having a tappet roller 68.

Each roller 68 is mounted contacting the working surface of cam 50, whereas each roller 66 is mounted contacting a further cam 69 integral with shaft 10 and the working surface of which is formed round the axis of shaft 10 itself.

Each sector gear 67 engages with two gears 51 mounted on respective shafts 52 relative to a pair of recesses 21 located between two pairs of adjacent recesses 21 controlled by respective sector gears 48 As shown in Fig. 4, cams 47 and 69, travelled along by rollers 46 and 66 respectively, are identical and each present a working surface consisting of a low section 70, a raised section 71 and two sloping blending sections 72 a centre portion of one of which is travelled along successively by rollers 46 and 66 when respective recesses 21 travel over a piercing arc 73 the aperture of which essentially corresponds with that of slit 17.

Cam 50, on the other hand, is travelled along by alternating rollers 49 and 68 and, like cams 47 and 69, presents a working surface consisting of a low section of a low section 74, a raised section 75 and two sloping sections 76 a centre portion of one of which is travelled along successively by rollers 49 and 68 when corresponding rollers 46 and 66 travel along the said centre portion of the said sloping section 72 on respective cam 47 or 69.

When bell 25 is turned by drive gear 39, rollers 46 and 66 are caused to roll along the working surfaces of respective cams 47 and 69, and rollers 49 and 68 along the working surface of cam 50.

When one roller 46 rolls off the low section 70 on cam 47 and starts to roll along one of sloping sections 72, the relative roller 49 rolls off the corresponding low section 74 on cam 50 and starts to roll along a corresponding sloping section 76 on the same.

As rollers 46 and 49 roll along the said corresponding sloping sections 72 and 76, the relative rocker arm 42 and consequently the relative sector gear 48 are gradually turned round the axis of relative pin 43 between two distinct extreme angles, thus causing the relative two appendixes 55 to turn accordingly round their axes.

The drive ratio between each sector gear 48 and relative gears 51 is normally such that angular displacement of sector gear 48 between the said two extreme angles causes appendixes 55 to turn by over 360" round their axes. Obviously, when the said rollers 46 and 49 roll along the other pair of corresponding sloping sections 72 and 76, appendixes 55 are turned the opposite way back to their original positions.

In the foregoig arrangement, three cams,47,50 and 69, are employed solely on account of specific construction requirements, seeing as, for example, a single cam 50 having two grooves on its opposite side faces for enabling positive two-way guidance of rollers 49 and 68 would be sufficient for enabling angular control of sector gears 48 and 67 and so dispensing with cams 47 and 69 and rollers 46 and 66.

Furthermore, the provision of two gear chain units 40 and 41 is due solely to the need to maintain the diameter of roller 1 within certain limits. In fact, if the diameter of roller 1, and consequently also of the cams, were to be greatly increased, all the rocker arms 42 and 62 could be arranged on the same side of cam 50.

As shown in Figs. 2 and 3, after being deviated radially outwards by mirror 16 through slit 17, beam 8 encounters lens 18 which spreads it in a direction perpendicular to the axis of shaft 10. On encountering lens 19, the said widened beam is spread further parallel with the axis of shaft 10, in such a manner as to define a "patch" of light the width of which is as constant as possible and at least equal to the diameter of lenses 20.

Furthermore, at least in the arrangement shown, the size of the widened beam in the plane perpendicular to the axis of shaft 10 and corresponding to the size of piercing arc 73, is at least such as to sweep four consecutive lenses 20 at the same time.

As roller 1 turns, cigarettes 2 travel one after the other over piercing arc 73, at the same time turning round their axes owing to relative rollers 46 and 49 or 68 and 66 rolling along sloping sections 72 and 76 on cams 47, 50 and 69.

In more detail, before reaching piercing arc 73, cigarettes 2 start turning round their own axes until they reach an essentially constant rotation speed which is maintained over the entire piercing arc, at the end of which rotation speed of cigarettes 2 gradually runs down to zero. Furthermore, the angular displacement of rocker arms 42 and 62 by sloping sections 72 and 76 is such as to cause cigarettes 2 to make an essentially full turn round their axes as they travel over piercing arc 73.

Finally, the pulse frequency of source 7 is such that the number of pulses emitted in the time taken by each cigarette to travel over piercing arc 73 is equal to the number of holes 13 to be pierced in each cigarette.

In connection with the foregoing description, it should be pointed out that, thanks to special rotating device 14, cigarettes 2 are turned round their axes without undergoing any rolling strain, and that pierced holes 13 are extremely clean and accurate, owing to essentially no relative movement existing between each cigarette 2 and respective lens 20.

In connection with lenses 18 and 19, it should be pointed out that an elongated patch of light such as the one they produce and as described previously could be achieved using only one lens or a number of lenses in no way differing from the said lenses 18 and 19.

In connection with the length of the said patch of light, i.e. the length of piercing arc 73, it should be pointed out that its corresponding with the space occupied by at least four lenses is due solely to construction reasons designed, on the one hand, to enable the use of as small a source 7 as possible and, on the other, to maintain within certain limits the rotation speed of cigarettes 2 round their axes as they move over piercing arc 73.

Finally, the fact that each sector gear 48 and 67 is assigned two consecutive recesses 21 is also due to construction reasons, seeing as a rotation unit on which each recess 21 is assigned a respective sector gear or on which each sector gear controls three or more recesses 21 would be perfectly feasible.

Claims (8)

1. Device for piercing holes in rod-shaped items, particularly cigarettes, the said device comprising a conveyor, a number of moving recesses supported on the said conveyor crosswise in relation to the travelling direction of the same and each designed to house a respective item a laser source designed to emit a pulsating laser beam and a focusing device designed to focus the said laser beam successively on to the said moving items characterised by the fact that it comprises a diffusor located between the said source and the said focusing device; the said focusing device comprising, for each said recess, a focusing lens integral with the said conveyor and travelling with the same along a given route, and a rotating device being supported on the said conveyorforturning each said recess round its own axis.

2. Device according to Claim 1, characterised by the fact that the said diffusor comprises fixed lens means designed to define, along the said route travelled by the said focusing lenses a "patch" of light the length of which, measured along the said route, is greater than the diameter of the said focusing lenses and the width of which, measured crosswise in relation to the said travelling direction, is essentially equal to the said diameter.

3. Device according to Claim 2, characterised by the fact that the length of the said "patch" of light along the said route is such as to involve at least three of the said focusing lenses at the same time.

4. Device according to Claim 2 or 3, characterised by the fact that the said rotation device comprises a number of gear chains supported on the said conveyor and each connected to at least one respective said recess, and cam means designed to activate selectively the said gear chains for turning the said recesses through essentially one full turn round their axes as the relative said focusing lenses travel over the said "patch" of light.

5. Device according to any one of the foregoing Claims, characterised by the fact that the said conveyor consists of a roller mounted in rotary manner round its own axis; the said focussing lenses and the relative said moving recesses being evenly arranged round the periphery of the said roller the first inside the second.

6. Device according to Claim 4 or Claims 4 and 5, characterised by the fact that each gear chain comprises a rocker arm hinged to the said conveyor and supporting, at one end, a tappet roller connected to the said cam means and, at the other end, a sector gear each said recess having an integral gear connected to a respective said sector gear.

7. Device according to Claim 6, characterised by the fact that each said sector gear is connected to at least two said gears.

8. Device for piercing holes in rod-shaped items essentially as described with reference to the attached drawings.