GB2200749A

GB2200749A - Process and device for making a fibre rod for the tobacco processing industry

Info

Publication number: GB2200749A
Application number: GB08727939A
Authority: GB
Inventors: Wolfgang Siems; Andrzej Radzio
Original assignee: Koerber AG
Current assignee: Koerber AG
Priority date: 1986-11-28
Filing date: 1987-11-30
Publication date: 1988-08-10
Anticipated expiration: 2007-11-30
Also published as: DE3738983A1; DE3738983C2; GB8727939D0; GB2200749B

Abstract

A process and device for making a fibre rod are described, in particular for making filters or cigarettes or like smokable articles. A mobile fibre material rod (4) contains an additional material component (softener, water). By means of two measuring arrangements (37, 38) which record the influence of the rod components differently, the rod density is measured and differing first and second rod density signals are produced. In an evaluation arrangement (42) the first and second rod density signals are processed to form a difference signal, which represents a measure of the proportion of additional component in the rod, and is used to control an arrangement (33) which influences the proportion of additional component. The measuring arrangement (37) comprises an X-or beta-ray transmission sensor, and the arrangement (38) comprises an infra-red, light or ultra-violet transmission sensor. The arrangement (37) may be replaced by weighing scales (31a). In the case of cigarette rods, the difference signal may be used to control trimming disks which remove surplus material. <IMAGE>

Description

Process and device for making a fibre rod tor the tobacco processing industry.

The invention relates to a process and a device for making a fibre rod or tne toDacco processing industry.

No possibility has been known to date for determining the softener content of a filter rod or of sections separated from the rod continuously and rapidly during the production process with an adequate degree of resolution. The fact that accurate determination of the softener content in a filter rod has not been achieved to date, or only unsatisfactorily so, is probably essentially due to the fact that the filter rod material and the softener rod material have a certain chemical relationship to one another and for this reason can be distinguished from one another only to an unsatisfactory degree by known methods of measurement.

in order to be able to establish the softener content of filter bars, a process is proposed wherein filter bars with a proportion of softener are first removed from current production and weighed, and wherein the weight of these filter bars is compared with the weight of the same number of filter bars from current production which do not contain softener. The weight difference established corresponds to the softener content in the filter bars ( US-PS 3 865 016 ). A disadvantage of this process is that in order for the filter bars without softener to be removed, the supply of softener to the filter rod has to be interrupted, which is tantamount to interrupting the production of standard filter bars. Measurement is discontinuous, and can supply only a random kind of explanation of the softener content in the filter bars produced.A further known process for determining the softener content in filter rods is based on the measurement of nuclear magnetic resonance (GB-PS 2 120 075). Nuclear magnetic resonance measurement requires a certain finite time during which the article for measurement must be held in the measurement position, so that even this does not allow any continuous determination of the softener content in filter bars or in the filter rod.

Nuclear magnetic resonance is thus more likely to produce a random kind of statement on the content of softener in the filter rod or filter sections, though in this case it is not necessary to interrupt production.

To date there is also no process available either for measuring the moisture of a mobile wrapped or unwrapped tobacco rod, which in practice meets all requirements in respect of speed and resolution, accuracy and reliability. For the measurement of moisture on a wrapped cigarette rod in particular, no practicable proposals have to date been put forward.

The object of the invention is further to improve a process and a device of the type described at the outset, and in particular to propose a possibility for the continuous determination of quantities of additional material components in the fibre rod or in the rod sections separated from the fibre rod.

The problem is solved with a process of the type described at the outset according to the invention, in that a fibre material containing an additional material component is moved along a preset path, the fibre material is compressed to form a fibre rod, and by means of radiation penetrating the rod the rod density is measured and at least one rod density signal is created for determining the proportion of at least one of the material components of the rod. If according to the invention a rod density signal is created for determination of the proportion of dry fibre material, i.e. if the quantity of the dry mass in the rod is determined and the quantity of dry fibre material is adjusted according to the rod density signal, the invention makes possible a simple adjustment of the dry weight.

According to the invention preferably at least two rod density measurements are undertaken, recording the influence of the rod components differently, and differing first and second rod density signals are created, which are processed according to a further continuation of the invention to form a comparison signal corresponding to the proportion of a rod component in the rod.

If the differing rod density signals are processed to form a comparison signal corresponding to the proportion of dry fibre material, here too there is the possibility of adjusting the dry weight, if the quantity of dry fibre material in the rod is adjusted according to the comparison signal. From the first and second rod density signal a difference signal can be created according to the invention, which represents a measure of the proportion of added material component contained in the fibre rod. A possible additional material component according to the invention is in the first place a liquid which is contained in the filter material strip or rod, the quantity whereof in a continuation of the invention is influenced according to the comparison signal in the sense of adjusting a pre-set proportion in the fibre rod.

To create a first rod density signal the invention provides for undertaking a first rod density measurement by means of nuclear radiation penetrating the rod. To create a second rod density signal, a further embodiment of the invention undertakes a second rod density measurement by recording the intensity of light beamed into the rod and penetrating it.A particularly preferred embodiment of the invention consists in using for rod density measurement to create the second rod density measurement infra-red radiation penetrating the rod. lt has in fact surprisingly been established that the intensity of the light penetrating the rod, and in particular of infra-red radiation of suitable wavelength, is influenced not at all or only to a negligible extent by the quantity of material component additionally contained, in particular by the liquid content of the rod, so that the density measurement signal obtained on the basis of the density measurement with light penetrating the rod is a measure of the quantity of fibre material contained in the fibre rod.Infra-red light in a broad wavelength range around 950 nm, hardly influenced at all by the liquids contained in the rod, appears particularly suitable in this context. lnfra-red light of about 1700 nm is also regarded as very suitable. Even larger infra-red wavelengths should not be excluded for density measurement purposes. Rod density measurement by means of nuclear radiation penetrating the rod, or density measurement by weighing rod sections on the other hand produce rod density signals which represent the quantity of all components contained in the fibre rod. The difference between rod density signals obtained by nuclear radiation and weighing on the one hand and by infra-red radiation on the other thus represents a measure of the quantity of material component additionally contained in the fibre material strip.It is important that the two methods of measurement record at least one rod component (preferably the liquid) differently, as then the proportion of this rod component in the rod can be established according to the invention.

Normally the rod density measurements are conducted on the continuously mobile fibre rod. According to a variant of the invention however, it is also possible to undertake at least one of the rod density measurements to create one of the rod density signals after the separation of rod sections from the fibre rod, on the separated rod sections. This density measurement on separated rod sections can be carried out by weighing according to the invention.

A further embodiment of the invention provides for a rod density measurement to be undertaken by means of X-ray radiation penetrating the rod, to create one of the rod density signals.

According to a special embodiment of the invention the softener content of a filter rod is determined by applying a softener as an additional material component to a strip of filter material moving along a pre-set path, and by taking at least two rod density measurements recording the influence of the softener differently. On the basis of these rod density measurements, varying density signals are created, which are processed to form a comparison signal corresponding to the proportion of softener in the filter rod. This comparison signal can be used to control the application of the softener to the filter material strip, and thus to adjust the proportion of softener in the filter rod.

Another special embodiment of the invention involves determining the proportion of moisture in a tobacco rod. For this the invention provides that a tobacco rod moving along a pre-set path contains moisture (water) as additional material component. To determine the proportion of moisture in the tobacco rod, at least two rod density measurements recording the influence of moisture differently are undertaken, and differing rod density signals are created. The differing rod density signals are processed to form a comparison signal corresponding to the proportion of moisture in the tobacco rod, and this signal can also be used to influence the moisture content in the tobacco rod.

In a device of the type initially described, the task upon which the invention is based is fulfilled according to the invention by providing conveying means to move a fibre rod containing an additional material component along a pre-set path, and a measuring device to measure the rod density and to create rod density signals corresponding to the rod density, for determining the proportion of at least one of the material components in the rod.

A very advantageous dry weight adjustment is obtained according to the invention by connecting the measuring arrangement to an evaluation arrangement, in that the evaluation arrangement is developed from the rod density signals forming control signals corresponding to the proportion of dry fibre material in the rod, and in that according to these control signals the arrangement controls a control means for influencing the quantity of dry fibre material in the sense of adjusting this quantity of fibre material. Here according to the invention preferably at least two measuring arrangements recording the influence of the rod components differently are provided to determine the rod density and to create differing first and second rod density signals.

The measuring arrangements are connected to an evaluation arrangement processing the rod density signals to form a comparison signal, whereby the evaluation arrangement is designed to emit a control signal representing the quantity of dry fibre material in the rod, and a control means for influencing the quantity of dry fibre material according to the control signal in the sense of adjusting this fibre material quantity is connected to the evaluation arrangement.

In a development of the invention, the evaluation arrangement has a difference former, which from the differing rod density signals forms a difference signal as comparison signal, representing a measure of the proportion of at least one of the material components contained in the fibre rod. According to the invention, means are provided for influencing the quantity of the additional material component contained in the rod, which means are connected to a control arrangement, associated with the evaluation arrangement, adjusting the quantity of additionally applied material component according to the difference signals in the sense of supplying a pre-set quantity.

As a first measuring arrangement for determining the rod density and for creating a first rod density signal, a nuclear measuring head is preferably provided. The nuclear measuring head records in the same way all components of the rod, and emits a corresponding density signal.

As a second measuring arrangement for determining the rod density and for creating a second rod density signal, according to the invention preferably an optical measuring head is provided, penetrating the rod with light, whereby as optical measuring head advantageously a measuring head penetrating the rod with light in the infra-red range of the spectrum is used. This optical measuring head surprising records essentially only the quantity of fibre material contained in the fibre rod, but is influenced not at all or only to a negligible extent by the material component additionally applied. For this purpose according to the invention an optical measuring head operating in the infra-red wavelength range around 950 nm appears particularly suitable. Wavelengths up to 1600 nm also appear very suitable.

Density measurement with at least one of the measurement afrarlgefflents is not confirmed oselusively to the continuous fibre rod. According to a development of the invention a cutting arrangement can be provided for separating rod sections from the fibre rod, and at least one of the measuring arrangements for determinng the rod density can be located downstream behind tise cutting arrangement. Here a set of scales is the first measuring arrangement considered, which scales, like the nuclear measuring head, record all rod constituents in like manner. This embodiment of the device according to the invention thus also allows density measurement on rod sections separated from the fibre rod.

A special embodiment of the device according to the invention for determining the moisture contained in a tobacco rod consists in providing conveying means for moving a tobacco rod containing as additional material component a moisture (water), along a preset path, at least two measuring arrangements recording the influence of the rod components differently, for determining the rod density and for creating differing rod density signals, and an evaluation arrangement processing the rod density signals to form a comparison signal representing the proportion of moisture in the rod. The corresponding development of the device for determining the proportion of softener in a filter rod is notable for the fact that conveying means- for moving a filter rod containing a softener (triacetin) as additional material component along a pre-set path, at least two measuring arrangements recording the influence of the rod components differently for determining the rod density and for creating differing rod density signals, and an evaluation arrangement processing the rod density signals to form a comparison signal representing the proportion of softener in the rod are provided.

One of the measuring arrangements for determining rod density can, according to a development of the invention take the form of an X-ray measuring head penetrating the rod with X-rays.

The particular advantage of the invention. consists in the fact that for the first time it is possible continuously and in a rapid and practicable manner to determine a quantity of moisture or softener contained in a tobacco or filter rod during the production process. The determination of the quantity of the additional component concerned is based on a two-fold density measurement which is executed without sampling and interrupting production. The high resolution of the measurement is particularly advantageous, making it possible to allocate measurements of the quantity of the additional component to all rod sections. The invention also offers the possibility of an adjusted supply and application of the additional material component to the tobacco rod or filter material strip. This also produces an improved rod quality at high production rates.A particular advantage of the invention also consists therein that it makes a dry weight adjustment on the rod machine a simple procedure.

The invention is now explained in greater detail with reference to the drawing wherein Fig. 1 represents a schematic view of a device according to the invention.

Fig. 2 is an enlarged representation of the measuring arrangement used.

In Figure 1, as an example of a device according to the invention, a machine for making a filter rod, in particular for making filters for cigarettes and like smokable articles is shown, in a schematic side view. This device consists of two main structural groups, a preparing arrangement 1 for a filter tow which is supplied in a continuous strip of filter material arid a processing arrangement Z tor making wrapped filter rods.

The preparing arrangement 1 comprises a pair of rollers 3 for continuous withdrawal of a continuous strip 4 of filter material from a bale 6. Upon withdrawal from the bale 6 the strip of filter tow passes, on its way to the pair of rollers 3 over which it is guided by way of a deflecting roller 5, through two air nozzles 7 and 8 which serve to spread and loosen the tissue of the strip of filter material. The pair of rollers 3 is followed by two additional pairs of rollers 9 and 11 between which is disposed an applicator arrangement 12 for the application of softener to the strip 4 of filter material which is guided in spread-out condition between the pairs of rollers 9 and 11.As regards the individual rollers of the pairs of rollers 9 and 11, the periphery of one roller of each pair is preferably provided with grooves whereas the counter roller exhibits a smooth surface of elastic material. All of the-pairs of rollers 3, 9 and 11 are adapted to be driven by a main drive motor 13 by way of belt transmissions 13a to c. Instead of a main drive motor 13, it is also possible to provide one or more separate drives for the pairs of rollers.

The rotational speed of the pair of rollers 3 is lower than that of the pair of rollers 9 so that the pairs of rollers 3 and 9 constitute a stretching device. The rotational speed of the pair of rollers 3 is variable by way of a transmission 14, the transmission whereof can be altered by an adjustable adjusting motor 16.

The speed ratio of the pairs of rollers 3 and 9 determines the extent of stretching of the filter material strip 4. In the illustrated embodiment, the braking rollers 3 are driven.

However, they can also constitute drag rollers, which act as braking rollers due to their frictional relationship.

A softener liquid is applied at a predetermined rate in the applicator arrangement 12 to the spread-out and stretched strip 4 of filter material.

The prepared'strip 4 of filter material, which has been sprayed with softener advances by way of the pair of rollers 11 from the preparing arrangement 1 into the inlet funnel 17 of the processing arrangement 2 in which it is condensed and deposited upon a strip 21 of wrapping material which is drawn off a bobbin 18 and is provided with glue by means of a glue applicator 19.

The wrapping strip 21 and the condensed strip 4 of filter material advance onto a format band 22 which conveys both components through a format 23 which drapes the wrapping material strip 21 around the filter material strip 4 and thus forms a continuous filter rod 24. The latter passes along a sealer plate 26 in which the adhesive seam is dried. Thereafter. filter rod sections 28 are continuously severed from the filter rod 24 by means of a blade apparatus 27 and the filter rod sections are transferred by an accelerator 29 into a depositing drum 31 in which they are conveyed in a transverse axial conveying direction.

From the depositing drum 31, the filter rod sections advance to a depositing belt 32 from which they are advanced to further processing or to intermediate storage.

The softener is supplied to the applicator arrangement 12 by means of a metering pump 33 by way of a supply line 34 from a supply 36 of softener.

According to the invention, a first and a second measuring device 37 or 38 are provided for determination of the rod density, which record the influence of the rod components differently. As shown in Fig. 2, the first measuring device constitutes a nuclear measuring head 37 with a beta ray source 39 and an ionisation chamber 41. This nuclear measuring head 37 records not only the percentage of filter material but also that of the softener in the filter rod and emits, by way of an amplifier 41a to an evaluation arrangement 42 a first rod density signal which corresponds to the quantity of all components in the rod.

According to the invention, the first measuring device 37 is associated with a second measuring device 38 in the form of an optical measuring head with a source 43 of infra-red radiation and an infra-red detector 44 which ascertains the intensity of infra-red radiation that issues from the radiation source 43 and penetrates the filter rod 24. The intensity of infra-red light which penetrates the rod is not influenced by the percentage of softener in the rod, so that the infra-red detector 44 transmits, by way of an amplifier 44a, to the evaluation arrangement 42 a second rod density signal which corresponds only to the percentage of filter material in the filter rod 24. In the evaluation arrangement 42, a difference former 46 (compare Fig.

1) creates from the first and second rod density signals a difference signal which corresponds to the percentage of softener in the filter rod 24. This difference signal can be displayed in a display arrangement 47, which is indicated in Fig. 2 by broken lines, as the quantity of softener of the density of softener.

According to Fig. 1, the difference signal is transmitted to a comparator 48 of the evaluation arrangement 42 and is compared as actual value with a pre-set reference value. Deviations of the difference signal from the reference value are transmitted by the comparator 48 in the form of a control signal to a control arrangement 49, the output signal whereof influences the metering pump 33 in the sense of applying a pre-set quantity of softener to the filter material strip 4. The invention thus makes it possible in a surprisingly simple way to achieve a reliable and rapid determination of the proportion of softener in the filter rod 24, as well as a selective influencing of the quantity of softener supplied to the applicator arrangement 12, so that it is possible continuously to apply a desired quantity of the softener. Thus, the invention enhances the reliability of the machine and the quality of the filter products which are made with the machine.

In accordance, with Fig. 1, both measuring devices 37 and 38 are located upstream of the blade apparatus 27. However, it is also within the scope of the invention to install at least one of the measuring devices 37 or 38 downstream, behind the cutting arrangement 27, so that the density of the filter rods which are separated fre the rod is measured. This does not influence the evaluation of the rod density signals thus obtained.

In place of the infra-red measuring head which is referred to in the description as a the second measuring head, it is also possible to use another optical measuring head which operates with radiation in the visible or ultraviolet section of the electromagnetic spectrum. This too is within the scope of the present invention.

Fig. 2 shows an optical measuring head with a light barrier 43, 44 which intersects the rod 24. This normally suffices for density measurement on a filter rod. However, in order further to improve the measurement, it is possible to use several light barriers which cross the rod at different angles and, if necessary, at longitudinally axially offset points, and which are operated in such a way that they monitor essentially the same section of the rod one after the other. In this manner it is possible to carry out several measurements which refer to one and the same section of the rod. This further enhances the reliability of determination of the percentage of the relevant material component. The measuring arrangement represented in Fig. 2 is described in connection with the determination of the triacetin quantity in a filter rod.With the same device according to the invention the proportion of moisture in a wrapped or unwrapped tobacco rod can also be determined. Here too that nuclear measuring head 27 records both the proportion of tobacco material and the quantity of water in the tobacco, and emits a first rod density signal via the amplifier 41a which corresponds to the quantity of all components in the tobacco rod. The optical measuring head provided as second measuring arrangement 38 with an infra-red radiation source 43 and an infra-red detector 44 does not establish, or establishes only to a negligible degree the proportion of water in the tobacco of the tobacco rod. The infrared detector thus emits a second rod density signal, which essentially corresponds only to the proportion of tobacco in the tobacco rod 24.The difference signal created by the difference former 46 from the first and second rod density signal thus corresponds to the proportion of water in the tobacco rod, which can be displayed in the display arrangement 47. In the comparator 48 the difference signal can be compared with reference value signal and processed in the control 'arrangement 49 to form a control signal, which can be used to influence the proportion of moisture in the tobacco rod. Thus, the invention also makes it possible in a surprisingly simple way to achieve a reliable and rapid determination of the moisture in a tobacco rod.

It is known that the density of a fibre material is in direct proportion to its weight or its mass. It therefore is possible to determine with a set of scales the weight or the mass of rod sections and to draw a direct conclusion from this as to the density of the fibre materials contained therein. For example a set of scales 31a as represented in Fig. 1, can be located behind the depositing drum 31 in the area of the depositing belt 32 in which the articles for weighing are transported to the set of scales. The density values obtained with the scales take account like those obtained with the nuclear measuring head of the influence of all material components contained in the rod section.

In the case of filter bars therefore the filter material and the softener applied are both included in this density measurement.

In the case of cigarettes this density measurement is based on the proportion of tobacco and the proportion of moisture in the fibre material. As described above the density values obtained by weighing are compared with those obtained by means of an optical density measurement. The difference again indicates the proportion of the additional material component, in the case of filters therefore the quantity of softener and in the case of cigarettes the quantity of water.

Both density measurements, those taken with the nuclear measurement head on the scales and those taken with the optical measuring head, can be undertaken on rod sections separated from the fibre rod. For this purpose the measuring heads can be located in a separate appliance, through which the rod' sections are pushed or conveyed by other means.

A set of scales suitable for determining the weight of rod sections is described for example in the Applicant's GB-PS 1 085 684.

It is stated above that the density measurement with an infra-red light barrier 38 or 38a essentially records the proportion of fibre material in the fibre rod, whereby moisture contained in the rod is included only to a negligible degree in the measurement.

This applies to water contained in the tobacco rod particularly in a broad wavelength range around 950 nm and 1700 nm, and also outside the absorption bands of the water. it is true in general terms that two density measurements which record the constituents of the fibre rod differently allow the formation of varying density measurements from which (e.g. difference or quotient formation) as described above a signal representing the proportion of the additional material component (moisture) can be formed. In many cases it is desirable to influence the quantity of dry mass in the rod, i.e. the quantity of dry fibre material, i.e. to keep it constant or to adjust it.The present invention offers a suitable possibility for this because the measurement of density by means of infra-red light in the stated wavelength ranges records only the dry mass and thus provides a measurement of dry mass. If by comparison of two differing density measurements, as described above, the moisture of the rod is determined, the difference between the overall mass, obtained for example by density measurement with a nuclear measuring head or by weighing, and the moisture is the dry mass. The density signal representing the dry mass permits adjustment of the dry mass, the so-called dry weight adjustment. For this a control signal dependent on the dry mass contained in the rod is produced by the evaluation arrangement 42.In the production of a cigarette rod 24, indicated by a broken line on the right-hand side of Figure 2, the control means 50 is controlled by this control signal, the means being developed as a surplus off-take arrangement with trimming disks 58 and a drive 50b, which moves the trimmina disks in the direction of the double arrow 50c towards the tobacco rod 24a guided on a suction rod conveyor 25 in the direction of the arrow 25a, and away from it, whereby less or more surplus 24b is removed. from the tobacco rod. The evaluation arrangoment 42 is connected to the control means 50 by way of a connection 42a, drawn in as a broken line. This arrangement thus allows a dry weight adjustment when a tobacco rod is made.

When a filter rod is made, the tow supply is controlled for example by influencing the stretching of the tow or the speed of supply of the tow to adjust the dry weight according to the control signal which depends on the dry mass proportion of the rod. According to Figure 1, the evaluation arrangement 42 for this is connected by way of a connection 42b, indicated by a broken line, to the adjusting motor which adjusts the speed ratio of the rollers 3 and 9 and thus the stretching of the tow.

The measuring arrangement shown in Fig. 2 can be allocated to any cigarette rod machine known per se, for example to a cigarette rod machine of the PROTOS type of the Applicant, between the format section and the cutting device. It is also possible to separate the nuclear measuring head 37 from the optical measuring head 38 and to locate the nuclear measuring head 37 in the usual way between the format section and the cutting device, while the optical measuring head is located in the area of the trimmer in such a way that it records the density of the as yet unclosed tobacco rod. This type of arrangement of the optical measuring head 38a is known in the interim, and is thus indicated only by means of a broken line in Fig. 2, whereby the sensor is denoted by 44b and the light source by 43a.

Claims

Patent Claims

1. Process for producing a fibre rod for the tobacco processing industry, characterised in that a fibre material containing an additional material component is moved along a pre-set path, the fibre material is combined to form a fibre rod, and the rod density is measured by means of radiation penetrating the rod, and at least one rod density signal is created for determination of the proportion of at least one of the material components of the rod.

2. Process according to Claim 1, characterised in that a rod density signal is created to determine the proportion of dry fibre material, and in that the quantity of dry fibre material is adjusted according to the rod density signal.

3. Process according to Claim 1, characterised in that at least two rod density measurements are taken, recording the influence of the rod component differently, and differing first and second rod density signals are created.

4. Process according to Claim 3, characterised in that the differing rod density signals are processed to form a comparison signal equivalent to the proportion of a rod component in the rod.

5. Process according to Claim 3 or 4, characterised in that the differing rod density signals are processed to form a comparison signal equivalent to the proportion of dry fibre material, and in that the quantity of dry fibre material is adjusted according to the comparison signal.

6. Process according to one of Claims 3 to 5, characterised in that a difference signal is created from the first and second rod density signals, which represents a measure of the proportion of the additional material component contained in the fibre rod.

7. Process according to one of Claims 1 to 6, characterised in that the additional material component contained in the fibre material is a liquid.

8. Process according to one of Claims 4 to 7, characterised in that the quantity of the additional material component is influenced according to the comparison signal in the sense of adjusting a pre-set proportion in the fibre rod.

9. Process according to one of Claims 1 to 8, characterised in that in order to create a first rod density signal, a first rod density measurement is undertaken by means of nuclear radiation penetrating the rod.

10. Process according to one of Claims 1 to 9, characterised in that in order to create a second rod density signal, a second rod density measurement is undertaken by recording the intensity of light beamed into the rod and penetrating it.

11. Process according to Claim 10, characterised in that infrared radiation penetrating the rod is used for rod density measurement to create the second rod density signal.

12. Process according to one of Claims 1 to 11, characterised in that at least one of the rod density measurements to create one of the rod density signals is taken after the separation of rod sections from the fibre rod, on the separated rod sections.

13. Process according to Claim 12, characterised in that one of the rod density measurements for creating one of the rod density signals is taken after the separation of rod sections from the fibre rod, by weighing a pre-set number of separated rod sections.

14. Process according to one of Claims 1 to 13, characterised in that, to create one of the rod density signals a rod density measurement is undertaken by means of X-rays penetrating the rod.

15. Process according to one of claims 1 to 14, characterised in that as an additional material component a softener is applied to a strip of filter material moving along a pre-set path, in that at least two rod density measurements are undertaken, recording the influence of the softener differently, and differing rod density signals are created, and in that the differing rod density signals are processed to form a comparison signal corresponding to the proportion of softener in the filter rod.

16. Process according to one of claims 1 to 14, characterised in that a tobacco rod moved along a pre-set path contains water as an additional material component, in that at least two rod density measurements are undertaken, recording the influence of the moisture differently, and differing rod density signals are created, and in that the differing rod density signals are processed to form a comparison signal corresponding to the proportion of moisture in the tobacco rod.

17. Device for making a fibre rod for the tobacco processing industry, characterised in that conveying means are provided for moving a fibre rod containing an additional material component along a pre-set path, and a measuring arrangement is provided to measure the rod density and to create rod density signals corresponding to the rod density, for determining the proportion of at least one of the material components of the rod.

18. Device according to claim 17, characterised in that the measuring arrangement is connected to an evaluation arrangement, in that the evaluation arrangement is developed so as to create control signals from the rod density signals, which control signals correspond to the propcrticn of dry fibre material in the rod, and in that according to these control signals, it controls a control means for influencing the quantity of the dry fibre material in the sense of adjusting this fibre material quantity.

19. Device according to claim 17 or 18, characterised in that at least two measuring arrangements recording the influence of the rod components differently, are provided for determining the rod density and for creating differing first and second rod density signals.

20. Device according to claim 19, characterised in that the measuring arrangements are connected to an evaluation arrangement processing the rod density signals to form a comparison signal.

21. Device according to claim 20, characterised in that the evaluation arrangement is developed to emit a control signal representing the quantity of dry fibre material in the rod, and in that a control means is connected to the evaluation arrangement to influence the quantity of dry fibre material in the rod according to the control signal, in the sense of adjusting this fibre material quantity.

22. Device according to claim 20 or 21, characterised in that the evaluation arrangement displays a difference former which creates from the differing rod density signals a difference signal as comparison signal, which represents a measure of the proportion of at least one of the material components contained in the fibre rod.

23. Device according to one of claims 17 to 22, characterised in that means for influencing the quantity of the additional material component contained in the rod are provided, and in that they are associated with a control arrangement, connected to the evaluation arrangement, adjusting the quantity of the material component applied additionally according to the difference signals, in the sense of supplying a pre-set quantity.

24. Device according to one of claims 17 to 23, characterised in that a nuclear measuring head is provided as a first measuring arrangement for determining the rod density and for creating a first rod density signal.

25. Device according to one of claims 17 to 24, characterised in that an optical measuring head, penetrating the rod with light, is provided as a second measuring arrangement for determining the rod density and for creating a second rod density signal.

26. Device according to claim 25, characterised in that a measuring head, penetrating the rod with light in the infra-red range of the spectrum, is provided as an optical measuring head.

27. Device according to one of claims 17 to 26, characterised in that a cutting arrangement is provided for separating rod sections from the fibre rod and in that at least one of the measuring arrangements is located downstream behind the cutting device, for determining the rod density.

28. Device according to claim 27, characterised in that one of the measuring arrangements for determining the rod density of the separated rod sections is a set of scales.

29. Device according to one of claims 17 to 28, characterised in that conveying means for moving a tobacco rod containing a moisture (water) as additional material component along a pre-set path, at least two measuring arrangements recording the influence of the rod components differently, to determine the rod density and to create differing rod density signals, and an evaluation arrangement processing the rod density signals to form a comparison signal representing the proportion of moisture in the rod, are provided.

30. Device according to one of claims 17 to 28, characterised in that conveying means for moving a filter rod containing a softener as an additional material component along a pre-set path, at least two measuring arrangements recording the influence of the rod components differently to determine the rod density and to create differing rod density signals, and an evaluation arrangement, processing the rod density signals to form a comparison signal representing the proportion of softener in the rod, are provided.

31. Device according to one of claims 17 to 30, characterised in that one of the measuring arrangements for determining the rod density is developed as an X-ray measuring head, penetrating the rod with X-rays.

32. Process for producing a fibre rod for the tobacco processing industry, substantially as herein described with reference to the accompanying drawings.

33. Device for making a fibre rod for the tobacco processing~ industry, substantially as herein described with reference to the accompanying drawings.