Method for feeding tobacco in a machine for manufacturing tobacco products   

BACKGROUND OF THE INVENTION

The present invention relates to a unit and a method for feeding tobacco in a machine by which tobacco products are manufactured.

The invention finds application to advantage in the art field of complete lines for the manufacture of tobacco products, and in particular cigarettes.

In a conventional line for manufacturing tobacco products, shredded tobacco passes along one or more ducts from a primary processing section into the feed and transport section of a cigarette maker; a partial vacuum is generated in the ducts, drawing the tobacco first into a header chamber, then from the header chamber into a feed chamber. The tobacco is directed en masse from the feed chamber into a carding unit and thereafter into a descending duct, or chute. Emerging at the bottom of the chute, the tobacco is transferred toward the bottom end of an ascending duct or chimney, enclosed at the top end by at least one moving conveyor consisting in an air-permeable aspirating belt by which the tobacco, drawn up through the chimney as a continuous flow of distinct particles, is attracted and gathered progressively into a continuous stream.

Externally of the chimney, the stream of tobacco advances from the aspirating belt toward the entry point of a station where it is fashioned into a continuous cigarette rod; the continuous rod will then be cut into single cigarette sticks, which are transferred to a filter tip attachment machine.

The schedules of a single manufacturing facility, and indeed of single production lines operating within the facility, each composed typically of a cigarette maker, a filter tip attachment machine and one or more cigarette packers, will normally include frequent changes of the particular brand in production, as dictated by demand. A change of brand means generally that the type of tobacco, the cigarette paper, tipping papers and filter tips, and the packet and carton blanks used for the new brand will be different to those in use previously.

Having shut off the supply of tobacco and paper to the cigarette maker, the machine itself is kept in operation until all the cigarette sticks have run out, followed by the final length of cigarette rod still in the process of being formed.

Once the machine has been emptied, an operator will proceed to change the type or blend of tobacco and, if envisaged, the type of paper used to wrap the rod, the tipping papers, and the filters.

Once the tobacco has been changed, the line can be started up again.

It will often become clear when the machine has already produced a certain quantity of cigarettes, for example from systems monitoring the quality of the single cigarettes turned out, that the tobacco is unsuitable and the product must be discarded, incurring considerable loss of time and materials. The error in question is frequently attributable to the fact that different types of tobacco can often be so similar in color as to be indistinguishable to the eye of an operator.

In addition, even when the change of tobacco has been accomplished without error, it is inevitable that traces of the tobacco used previously will remain in the cigarette maker, especially in the chute of the feed and transport unit, and mingle with the new tobacco. Likewise in this instance, a certain quantity of cigarettes must be discarded.

The object of the present invention is to provide a tobacco feed unit in a machine for manufacturing tobacco products, such as will be unaffected by the aforementioned drawbacks.

One object of the invention, in particular, aimed at minimizing the impact attributable to a change of brand in a machine for manufacturing tobacco products, is to provide a tobacco feed unit that will allow of verifying the selection of a certain type of tobacco and/or preventing different types of tobacco from becoming mingled in production.

Similarly, the object of the present invention is to provide a method of feeding tobacco in a machine for manufacturing tobacco products, such as will be unaffected by the aforementioned drawbacks.

A further object of the invention, in particular, aimed at minimizing the impact of a change of brand in a machine for manufacturing tobacco products, is to provide a method of feeding tobacco that will allow of verifying the selection of a certain type of tobacco and/or preventing different types of tobacco from becoming mingled in production.

SUMMARY

The stated objects are realized in a tobacco feed unit according to the present invention, applicable to a machine for manufacturing tobacco products, comprising means by which shredded tobacco is fed along a predetermined path toward a unit of the machine where tobacco particles are formed into a continuous stream, and sensing means deployed along the predetermined path, by which the tobacco is identified according to type before it reaches the forming unit.

The aforementioned objects are realized similarly in a method of feeding tobacco in a machine for manufacturing tobacco products, including the steps of shutting down the machine to suspend production of a first brand of tobacco product made from a first type of tobacco, replacing the first type of tobacco with a second type of tobacco used to manufacture a second brand of tobacco product, and activating sensors to identify the type of tobacco being handled by the machine before initiating production of the second brand of tobacco product.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which:

FIG. 1 is a perspective view showing a cigarette maker and part of a tobacco feed unit according to the present invention;

FIG. 2 is a schematic representation of the tobacco feed unit in FIG. 1, shown enlarged and in its entirety.

With reference to FIG. 1, numeral 1 denotes a machine, in its entirety, for manufacturing tobacco products 2 such as cigarettes, by way of example.

The machine, or cigarette maker 1, is equipped at the upstream end with a tobacco feed and transport section 3 by which a mass of shredded tobacco 4 is formed into a continuous flow of tobacco particles. The components of the feed and transport section 3 are housed in a vertically extending enclosure 5 delimited uppermost by a horizontal wall 6 and on either side by two vertical walls 7.

Shredded tobacco 4 is directed into at least one header chamber 11 surmounting the horizontal wall 6 and connected by way of at least one inlet duct 12 to a primary processing section denoted 13, shown schematically in FIG. 2. Leaf tobacco fed into this same section 13 is processed and conveyed by pneumatic means (not illustrated) along the duct 12 and into the chamber 11.

The section denoted 3, the inlet duct 12 and the outfeed stage of the section denoted 13 combine to establish a feed unit 8 that serves to direct the tobacco 4 along a predetermined path extending from the upstream section 13 toward a downstream unit 9 by which it is formed into a continuous stream 10.

The header chamber 11 connects on one side with a carding unit 14 to which it supplies the tobacco 4, and is equipped internally with a movable wall 11a such as can be operated intermittently to open and close the passage to the carding unit 14.

The carding unit 14 comprises a power driven feed roller, denoted 15, by which the shredded tobacco 4 is directed down into a lower chamber 16 delimited at the bottom by a conveyor belt 17.

The chamber 16 houses a carding drum or roller, denoted 18, rotatable about an axis 18a transverse to the two side walls 7 and occupying a position adjacent to the downstream end of the belt 17.

In addition to the carding roller 18, the unit 14 comprises a proportioning roller 19 set in rotation substantially tangential to the carding roller 18 and in the same direction.

With this arrangement, the shredded tobacco 4 can be directed by the feed roller 15 onto the belt 17 and then toward the carding roller 18, whereupon a layer of the shredded tobacco 4 substantially equal in thickness to the radial dimension of the carding teeth is transferred by the roller 18 away from the chamber 16 and beyond its position tangential to the proportioning roller 19.

Also associated with the carding unit 14 is an impeller roller 20 rotatable about an axis parallel to the axis 18a of the carding roller 18, of which the function is to take up the layer of tobacco 4 from this same roller 18 and shower the constituent particles, in the direction denoted F1, down into a substantially vertical descending duct or chute 21 delimited by a pair of side walls 22 set parallel one with another and with the axis 18a of the carding roller 18.

The bottom end of the chute 21 is located facing the periphery of a transport device 23 by which the tobacco 4 is conveyed from this same bottom end of the chute 21 toward the bottom end of an ascending duct or chimney 24, of which the top end connects with the unit 9 forming the continuous stream 10 of tobacco 4.

In the example illustrated, the aforementioned transport device 23 comprises a take-up roller 26 and an impeller roller 27 combining to transfer the shredded tobacco 4 away from the chute 21.

The take-up roller 26 is designed to project the tobacco 4 in the form of distinct particles onto a transport belt 28 moving from right to left as seen in FIG. 2, and angled upward with the runout end located beneath the inlet of the chimney 24.

In an alternative embodiment of the invention (not illustrated), the transport belt 28 could be replaced by a fluidized bed, of conventional type, consisting in a static surface extending between the chute 21 and the chimney 24, along which the tobacco 4 is caused to slide by a flow of air.

The top outlet end of the chimney 24 is enclosed by two aspirating belts 29 of the aforementioned unit 9, on which particles of tobacco collect and are formed gradually into relative streams 10 that will be fashioned ultimately into cigarettes 2.

Each stream 10 of tobacco is advanced together with a strip 30 of paper decoiling from a roll 31 and directed along a path passing through a print device 32, thence toward a garniture assembly 33 by which the strip 30 is draped around the stream 10 of tobacco to form a continuous cigarette rod 34. Whilst the invention is described with reference to a dual rod, twin-track type cigarette-making line, it will find application advantageously just the same in a single rod, one-track type line.

Each rod 34 advances toward a cutting station 35 at which it is divided by a rotary cutter device 36 into discrete cigarette sticks 37 of predetermined constant length, and more exactly, twice the length of a stick forming part of a single cigarette 2.

The cut sticks 37 are transferred to a filter tip attachment machine denoted M, not illustrated in detail, being conventional in embodiment.

The tobacco feed unit 8 further comprises sensing means 38 able to identify the type of tobacco 4 being handled by the feed and transport section 3, before it reaches the unit 9 by which the particles are formed into stream 10. Such sensing means 38 operate along the predetermined path leading from the outfeed of the primary processing section 13 to the unit 9, that is to say, by way of the inlet duct 12, the header chamber 11 and carding unit 14, the descending duct or chute 21, the transport device 23 and the ascending duct or chimney 24.

The sensing means 38 in question comprise at least one sensor 39 mounted in close proximity to the predetermined path and preferably at points where the tobacco 4 tends to accumulate, so as to maximize the response of the sensor 39.

The sensors 39 are wired to a central processing unit, or CPU 40, by which signals are received from the selfsame sensors 39 and compared with stored parameters relative to different types of tobacco 4 in such a way as to provide a data item identifying the tobacco 4 advancing currently through the feed and transport section 3.

The sensors 39 adopted would be of conventional olfactory type, for example, capable of detecting gaseous substances given off by the tobacco 4 and peculiar to each variety or blend. Such sensors use semiconducting metal oxide thin film technology, and when heated to temperatures of 300-400° C. will register a thermal conductivity determined by the gases to which they are exposed.

Alternatively, use could be made of infrared sensors, likewise conventional, which measure the extent to which the tobacco 4 absorbs predetermined frequencies in the infrared range, the rate of absorption being dependent on the presence and percentages of certain substances in the tobacco 4. The parameters stored in the CPU 4 are packets of information relative to the spectral absorption of each type of tobacco.

The accompanying drawings illustrate a plurality of sensors 39 placed at various points of the feed unit 8. In practice, all of these or only certain of them might be included.

One or more sensors 39 can be installed upstream of the carding unit 14, considered relative to the flow of tobacco 4 advancing along the predetermined path aforementioned, so as to identify a new type of tobacco 4 at the infeed stage before an entirely new production run is begun by the machine 1, as explained below. The sensor 39 in question could be placed at any given point along the inside of the inlet duct 12, for example immediately downstream of the primary processing section 13, or upstream of the inlet duct 12 and at the outfeed stage of this same section 13, or immediately upstream of the header chamber 11, or preferably, in the header chamber 11 itself.

Alternatively, or in addition to the sensors 39 placed upstream of the carding unit 14, sensors 39 could also be positioned downstream of the carding unit 14, for example in the chute 21, along the transport device 23 or in the chimney 24, of which the function would be to verify that the cigarette maker 1 has been emptied correctly and entirely of material from the previous run. Given that these sensors 39 are best located at points where the tobacco 4 tends to accumulate, as explained above, and in particular when the machine 1 is shut down during a changeover from one brand to another, the optimum locations will be in the chute 21 and, if installed, in the fluidized bed (not illustrated).

The brand changeover procedure involves shutting down both the cigarette maker 1 and the downstream filter tip attachment machine M, so as to suspend the production of a first brand of cigarettes 2 manufactured from a first type of tobacco 4 and using other brand-specific materials, such as the cigarette paper, filter tips, filter papers and possibly the types of ink and gum.

In particular, adopting the method of feeding tobacco 4 according to the present invention, the flow of the first type of tobacco 4 is suspended at the primary processing section 13, as also is the supply of paper 30 from the rolls 31, whereas the cigarette maker 1 continues operating in order to use up the tobacco 4 still occupying the carding unit 14, at least in part, and cause the remainder of the cigarette rod 34 still being formed in the garniture assembly 33 to run out of the machine.

Once the cigarette maker 1 has been shut down, clean-up systems of conventional type will come into operation to clear the more easily accessed parts of the machine, albeit residual amounts of shredded tobacco will inevitably remain in the carding unit 14, and particularly in the chute 21, above the take-up roller 26.

The tobacco 4 occupying the primary processing section 13 is replaced with a second type or blend, or alternatively, the entire section 13 is replaced with another section 13 containing the second type of tobacco 4. If envisaged, similarly, the paper 31 utilized for the cigarette rod 34 will be replaced, likewise the ink in the print device 32 and the gum solutions.

Before commencing a new production run with a second brand of cigarette 2, the sensing means 38 are activated so as to verify the type of tobacco 4 passing through the feed and transport section 3.

In a first test cycle, determined by a relative software program and implemented by the CPU 40, the wall 11a of the header chamber 11 is closed off so that new tobacco 4 of the second type cannot pass into the carding unit 14, and pneumatic means are activated by the CPU 40 to direct a predetermined quantity of the new tobacco 4 from the processing section 13 into the header chamber 11.

Once a sufficient quantity of the tobacco 4 has collected in the chamber 11 or in the duct 12, the sensor or sensors 39 placed upstream of the carding unit 14 are activated to run a spot check, effected in a matter of seconds, or tenths of a second, and serving to ensure that the tobacco 4 is indeed of the correct type. Accordingly, the CPU 40 processes the signal received from the sensor 39 to obtain a value indicating the type of tobacco 4 effectively contained in the header chamber 11 and compares this same value with a reference parameter entered by the operator and corresponding to the second type of tobacco 4 used in the new brand. If the tobacco 4 detected is that of the new brand, the CPU 40 responds by initiating the new production run, either automatically or when enabled by the operator; conversely, if the tobacco is not of the right type, the CPU 40 will output an error signal by means of a conventional indication system.

Alternatively, or in parallel with the first test cycle, the cigarette maker 1 may run a second test cycle, likewise implemented by the CPU 40, with the aid of the sensors 39 positioned downstream of the carding unit 14.

In the second cycle, the sensor or sensors 39 placed downstream of the carding unit 14, located preferably within the chute 21 immediately above the take-up roller 23, will identify the type of tobacco 4 before and/or immediately after the cigarette maker 1 is started up, so as to ensure that the first type has been entirely used up. Only after verifying that there are no longer any traces of the first type of tobacco 4, or that the tobacco present is the right type, will the CPU 40 respond by initiating the new production run, automatically or when enabled by the operator.

It would also be possible, likewise in accordance with the feed method disclosed, for the CPU 40 to establish initially which type of tobacco 4 is in the chute 21 and thereafter, once the cigarette maker 1 has been restarted and running for a short interval, take a second reading internally of the chute 21 to ensure that the tobacco in the carding unit 14 is in effect only of the second type.

The objects stated at the outset are realized by the unit and the method according to the present invention, and the drawbacks associated with the prior art thus overcome.

In effect, with sensing means 38 deployed along the predetermined feed path, it becomes possible to make certain that the correct type of tobacco 4 has been selected and ensure that different types of tobacco will not mingle when changing over from one brand to another on a single cigarette making line.

In particular, the first test cycle implemented using sensors 39 placed upstream of the carding unit 14 serves as a preliminary sample test on the tobacco 4 about to be fed into the system.

Furthermore, the second test cycle implemented with the aid of sensors 39 placed downstream of the carding unit 14 serves to verify whether or not there is still any trace of the tobacco 4 in use previously, at points where accumulation is more likely to occur, so that the appropriate measures can be taken before initiating the new production run.