EP3174410B1

EP3174410B1 - Apparatus and method for the production of filters for cigarettes or other smoking articles

Info

Publication number: EP3174410B1
Application number: EP15754024.6A
Authority: EP
Inventors: Antonella Giannini; Alberto Monzoni
Original assignee: Montrade SpA
Current assignee: Montrade SpA
Priority date: 2014-08-01
Filing date: 2015-07-31
Publication date: 2018-08-29
Anticipated expiration: 2035-07-31
Also published as: RU2673139C2; EP3174410A1; RU2017104507A3; WO2016016862A1; PL3174410T3; CN107072290A; RU2017104507A

Description

The present invention relates to methods and apparatus for the production of filters for cigarettes or other smoking articles.
Machines for producing filters for cigarettes or other smoking articles, able to produce filters made of cellulose acetate fibres bonded together with the addition of a plasticizer agent, tipically triacetine (glycerol triacetate), are old and well-known. A machine of this kind is disclosed for example in document EP 2 636 321 A1 of the same Applicant. The addition of a plasticizer agent is adopted both for wrapped acetate filters (i.e. filters which are wrapped in a web of paper or other material), and for non-wrapped acetate filters (NWA), i.e. filters which have no wrap.
In the production of filters of the above indicated types, the action of the plasticizer agent is completed upon a given aging time, after which the filters pass from a relatively soft consistency to a relatively hardened state, with a simultaneous elastic recovery, which, in the case of NWA filters, gives origin to a diameter reduction. The aging time may vary from a minimum of about 40 minutes to a maximum of 72-120 hours, as a function of the degree of hardness and, in the case of NWA filters, as a function of the degree of diameter stabilization which is necessary to achieve for enabling subsequent handling and/or processing operations on the filters. As a consequence, at the outlet of the filter making machine, it is necessary to provide a buffer for accumulating the filters (in the case of short aging) or off-line storage areas (in the case of long-lasting aging). In the case of off-line storage, the costs for the required logistic may become very huge. In the case of NWA filters of the so-called "shaped" type, i.e. filters having a tubular form with an inner cavity having a shaped profile or filters having an outer shaped profile, the hardening and diameter reduction which derive from the aging process pose problems and involve an increase in costs, since said aging has a duration of several days. Documents EP 1 127 498 A1 , EP 1 314 364 A1 , EP 1 905 317 A1 and DE 10 2005 058091 describe apparatus for providing accelerated aging of the filters.
The object of the present invention is that of overcoming the above mentioned drawbacks of the prior art, by providing an apparatus which is more efficient, more compact and safer with respect to the known solutions.
In view of achieving this object, the invention provides an apparatus for the production of filters for cigarettes or other smoking articles, characterized in that it comprises filter making means and conveying means for feeding the produced filters through a drying chamber which is adapted to provide an accelerated aging of the filters, and in that said apparatus further comprises means for varying the speed at which said filters go through said drying chamber, on the basis of at least one detected parameter which is indicative of the humidity contained in said filters, so that, for a given power of said radiofrequency generator device, the residence time of the filters within the drying chamber is adjusted so as to ensure a substantial elimination of the humidity content of the filters.
The invention also provides a method for producing filters for cigarettes or other smoking articles, which makes use of the above mentioned apparatus.
Radiofrequency drying devices have been known and used for some time (see for example EP 1 369 654 A1 and EP 1 544 561 A1 ). This technology is based on the behaviour of a dielectric material such as water, which, when subjected to an electric field undergoes a polarization of its molecules, i.e. a deformation and/or an orientation according to the lines of the electric field. When the electric field is alternated, i.e. it is an oscillating field, the polarization direction is inverted at each inversion of the electric field. The water molecules are forced to move with the same frequency as that of the oscillating electric field, thus dissipating energy by intermolecular friction and consequently generating heat which causes water evaporation. The elimination of the water content can be accelerated by activating air circulation within the drying chamber.
The Applicant has found that the technology of radiofrequency dryers is ideal for the application forming the subject of the present invention. Due to the application of a high frequency oscillating electric field, aging of the filters coming from the filter making machine is accelerated, due to the quick elimination of the water content.
A radiofrequency generator device has a further advantage of being very compact and ensuring a high degree of safety, which renders its application to the apparatus according to the invention an ideal one. Furthermore, the effects of the radiofrequency generator device can be controlled and foreseen precisely for a given device power. Therefore, by using this device it is possible to reliably control actual elimination of the entire humidity content from the filters, without jeopardizing the productivity of the plant, i.e. while keeping the conveying speed of the filters at the maximum possible value.
To this end, the apparatus of the invention comprises sensors means of any known type (such as infrared sensors or capacitive sensors) for detecting the residual humidity content in the filters (or for detecting any other parameter which is indicative of the humidity content, such as even the weight of the filters). To the filter feeding conveyor there is associated an actuating electric motor, which is controlled by an electronic control unit according to a closed loop logic, on the basis of the detected value of the above mentioned parameter. The control unit then attends to varying the speed at which the filters go through said drying chamber on the basis of said detected parameter, so that, for a given power of said radiofrequency generator device, the residence time of the filters within said drying chamber is adjusted so as to ensure a substantial elimination of the humidity content from the filters.
Theoretically, the invention is applicable to the production of filters of any known type, but it is particularly advantageous in the production of filters made of cellulose acetate fibers additioned with a plasticizer agent (both for wrapped acetate filters and for non-wrapped acetate filters or NWA) in order to dramatically accelerate the aging process.
In this application, the radiofrequency generator device associated to the drying chamber is therefore controlled so as to achieve a predetermined degree of hardening of the filters and/or a predetermined degree of diameter stabilization of the filters.
According to the invention, the drying chamber adapted to accelerate aging of the filters can be arranged along the line downstream of the filter making means, or outside of said line.
Furthermore, said drying chamber which is adapted to accelerate the aging of the filters can be incorporated within the same machine which comprises the above mentioned filter making means, or it can be arranged downstream of said machine.
It is to be noted that in machines for production of acetate filters (such as in the machine described in document EP 2 636 321 A1 of the same Applicant) it is known to provide a drying station inside the machine, but simply for drying the surface of the tow of filtering material which advances along the machine, downstream of a fiber stabilizing station, where fibers are invested with water vapour. This drying station makes use of blown air and only causes a drying of the surface of the tow, with no possibility of affecting in any way the aging time which is required as a consequence of the application of the plasticizer agent, as it happens instead in the case of the present invention.
Further features and advantages of the invention will become apparent from the description which follows with reference to the annexed drawings, given purely by way of non-limiting example, in which:

figures 1, 2 are a plan view and an elevational view of a first embodiment of a system according to the invention,
figure 1A is a perspective view at an enlarged scale which shows the arrangement of the filters on the conveyor belt of the drying tunnel, and
figures 3, 4 are a plan view and an elevational view of a further embodiment of the present invention.

Figures 1, 2 of the annexed drawings show a line for production of filters for cigarettes or other smoking articles, including a first station 10 constituted by a machine of any known type, which includes filter making means for the production of filters constituted by cellulose acetate fibers added with a plasticizer agent. As already indicated, a machine of this type is for example described and shown in document EP 2 636 321 A1 of the same Applicant. The machine shown in the annexed drawings is namely the machine marketed under the name "MONO" by the Applicant. However, as also already indicated, the invention is applicable in general to any type of machine for producing filters and to any type of filters.
In the specific case of the above mentioned known machine which is shown here, this machine comprises filter making means which include: means for handling and subsequently forming a tow of fibers of cellulose acetate which are picked up from a bale of fibers, means for adding a plasticizer agent in order to bond the fibers together and form a cylindrical tow, means for stabilizing the tow by a vapour flow, means for drying the surface of the tow and means for cutting the tow in order to obtain filters of predetermined lengths.
In the filters produced by machine 10 the action of the plasticizer agent is completed upon a given aging time, after which the filters pass from a relatively soft consistency to a relatively hardened state, with a simultaneous elastic recovery of the fibers which, in the case of NWA filters, gives origin to a diameter reduction.
The present invention enables a dramatic decrease in the aging time of the filters. To this end, the invention provides a drying chamber downstream of said filter making means and in particular downstream of said means for cutting the filters according to a desired length.
The drying chamber could be incorporated into the machine 10 which includes the above mentioned filter making means, but in the illustrated example it is provided along the conveyor line downstream of machine 10. It would be also possible to provide the drying chamber downstream of the machine 10, but off-line, such as at a parking area served by an accumulation (buffer) conveyor.
In the illustrated example, the drying chamber is a tunnel-like chamber arranged along the line between the outlet of machine 10 and the final end of the line (where, in the illustrated example, a station 20 is provided for storage of filters within filter-carrying cartridges, for subsequent transportation thereof).
Through the tunnel-like drying chamber 30 there extends a conveyor belt 40 on which the filters F coming from machine 10 are conveyed. Preferably, filters F are loaded on the conveyed belt 40 (by guiding means of any known type) so that they are arranged transversally on belt 40, forming a number of superimposed layers with staggered pitch (see figure 1A).
In the case of the invention, whatever is the arrangement of the drying chamber (inside or outside machine 10, along the line or off-line), this drying chamber comprises a radiofrequency generator 50 of any known type, comprising an oscillator adapted to generate a high frequency oscillating electric field which is applied to electrodes arranged inside the drying tunnel. The details of construction of the radiofrequency device 50 are not shown herein, since this device can be made in any way known to the experts in the field.
As already indicated in the foregoing, the technology of radiofrequency is based on the behaviour of a dielectric material such as water, which, when subjected to an electric field undergoes a polarization of its molecules, i.e. a deformation and an orientation according to the lines of the electric field. If the electric field is an alternated (oscillating) field, the direction of polarization becomes inverted at each inversion of the electric field. The water molecules are forced to move at the same frequency as the frequency of the field, thus dissipating energy by intermolecular friction which produces the heat required for drying.
In the application according to the invention, a quick elimination of the water content from the filters, with resulting drying of the filters and hardening and/or diameter stabilization thereof is obtained.
Tests conducted by the applicant have shown that in the case of NWA filters the desired diameter reduction is achieved almost instantaneously. This diameter reduction depends upon the quantity of acetate and plasticizer agent, but can be evaluated to be of about 0.06 mm for a circumference of 24 mm, for common filters of the "shaped" type.
The solution of figures 1, 2 has a horizontal drying tunnel, whereas the solution of figures 3, 4 has a vertical tunnel, in which the filters are caused to advance vertically while they are held clamped between two vertical conveyor belts 41, 42. As shown in figure 4, at the outlet of the vertical tunnel, at the upper end thereof, the conveyor belts 41, 42 extend further along a path which returns vertically downwardly to feed the dried filters to station 20.
In both embodiments, the apparatus of the invention comprises one or more sensors HS of any known type (such as infrared sensors or capacitive sensors) for detecting the residual humidity content (or for detecting any other parameter which is indicative of the humidity, such as even the weight of the filters). To the filter feeding conveyor there are associated one or more driving electric motors M at least one of which is controlled by an electronic control unit E according to a closed loop logic on the basis of the value of said parameter detected by sensor HS. Control unit E then attends to controlling electric motor M so as to vary the speed at which the filters go through the drying chamber, on the basis of said detected parameter, so that, for a given power of said radiofrequency generator device, the residence time of the filters within said drying chamber is adjusted so as to ensure a substantially elimination of the humidity content from the filters. As diagrammatically shown in the drawings, the electronic unit E can also be connected to an electronic control board of the radiofrequency device, for receiving an information on the operating power of this device. In this manner, it is possible to provide an automatic control such as that indicated above also in the case that the power of device 50 is varied.
Naturally, while the principle of the invention remains the same, the details of construction and the embodiments may widely vary with respect to what has been described and shown purely by way of example, without departing from the scope of the present invention.
As it appears from the foregoing description, the basic concept of the present invention lies in the idea of providing a drying chamber arranged and configured so as to cause an accelerated aging of the filters after that they have been shaped and cut at the desired length by the filter making means. The drying chamber can be provided along the line downstream the machine which includes the filter making means, or off-line, or also it can be incorporated within the machine which comprises the filter making means. Although any suitable technology can be used for the drying chamber, studies and texts of the Applicant show that the technology of radiofrequency driers is particularly advantageous.
The radio frequency generator device, due to the nature itself of the principle used (increase of the kinetic energy of water molecules) provides the advantage of being very compact and of ensuring a high degree of safety, which renders its application to the apparatus of the invention an ideal one. Furthermore, due to the present invention, the effects of the radiofrequency generator device can be controlled and foreseen precisely, for each given power of the device. By using this device, it is therefore possible to reliably control a really total elimination of the humidity content from the filters, without jeopardizing the productivity of the plant, i.e. while keeping the conveyor speed of the filters at the maximum possible value.

Claims

Apparatus for the production of filters for cigarettes or other smoking articles, comprising filter making means (10) and conveying means (40, 41, 42) for feeding the produced filters (F) trough a drying chamber (30) adapted to provide an accelerated aging of the filters (F), wherein to said drying chamber (30) there is associated a radiofrequency generator device (50), for generating a high frequency oscillating electric field in which said filters are immersed, characterized in that said apparatus further comprises means for varying the speed at which said filters go through said drying chamber, on the basis of at least one detected parameter, which is indicative of the humidity contained within said filters, so that, for a given power of said radiofrequency generator device (50) the residence time of the filters within said drying chamber is adjusted so as to ensure a substantial elimination of the humidity content from the filters.
Apparatus according to claim 1, characterized in that said filter making means (10) are adapted to make filters (F) constituted by fibers of cellulose acetate added with a plasticizer agent, and in that said radiofrequency generator device (50) associated to said drying chamber (30) is controlled so as to achieve a predetermined degree of hardening of the filters (F) and/or a predetermined degree of diameter stabilization of the filters (F).
Apparatus according to claim 1, characterized in that said drying chamber adapted to accelerate the aging of the filters is arranged along a line downstream of the filter making means, or outside of said line.
Apparatus according to claim 1, wherein said filter making means are incorporated within a filter making machine (10), characterized in that said drying chamber adapted to accelerate aging of the filters is incorporated within said machine or is arranged downstream of said machine.
Apparatus according to claim 1, characterized in that said conveyor means include at least one conveyor belt (40, 41, 42).
Apparatus according to claim 1, characterized in that said drying chamber (30) is in form of a horizontal or vertical tunnel.
Method for the production of filters for cigarettes or other smoking articles, comprising the steps of providing filter making means (10), and means for conveying the produced filters (F) to a drying chamber (30) adapted to cause accelerated aging of the filters (F), characterized in that to said drying chamber (30) there is associated a radiofrequency generator device (50), for generating a high frequency oscillating electric field in which said filters are immersed and in that said method further comprises varying the speed at which said filters go through said drying chamber, on the basis of at least one detected parameter, which is indicative of the humidity contained within said filters, so that, for a given power of said radiofrequency generator device (50) the residence time of the filters within said drying chamber is adjusted so as to ensure a substantial elimination of the humidity content from the filters.
Method according to claim 7, characterized in that said filter making means (10) are adapted to make filters (F) constituted by fibers of cellulose acetate added with a plasticizer agent, and in that said radiofrequency generator device (50) associated to said drying chamber (30) is controlled so as to achieve a predetermined degree of hardening of the filters (F) and/or a predetermined degree of diameter stabilization of the filters (F).