GB1596392A

GB1596392A - Method and arrangement for checking rod-like smokable articles for faulty wrappings

Info

Publication number: GB1596392A
Application number: GB4928777A
Authority: GB
Original assignee: Hauni Werke Koerber and Co KG
Current assignee: Koerber AG
Priority date: 1976-11-26
Filing date: 1977-11-25
Publication date: 1981-08-26
Also published as: JPS632589B2; FR2371890B1; FR2371890A1; JPS5386100A; DE2653735A1; IT1143718B

Description

(54) METTlIOD AND ARRANGEMENT OR CHECKING ROD-LIKE SMOKABLE ARTICLES FOR FAUliTYWRiAPPlNGS.

(71) We, HAUNI-WERKE KORBER & BR< CO KG., a German Company of Kampchaussee 12-22, 2050 Hamburg 80, Germany Federal Republic), do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: The invention relates to a method for checking rod-like smokable articles for faulty wrappings, which have an area of desired permeability to air, as they are conveyed at rightangles to their axes along a predetermined path, by forming a pressure drop between a space comprising a filling, surrounded by the wrapping and a space outside the wrapping and by forming a checking signal dependent on the permeability to air of the wrapping.

The invention also relates to an arrangement for checking rod-like smokable articles for faulty wrappings, which have an area of desired permeability to air, with a rotating checking conveyor comprising holders for retaining articles and with a checking device which comprises sealing means for the temporary separation of a space comprising a filling, surrounded by the wrapping from a space outside the wrapping of each article, connection means which connect one of the two spaces to a source of pressure and connection means which connect one of the two spaces to a measuring arrangement monitoring pressure differences.

The term "rod-like smokable articles" is intended to mean cigarettes, cigarilios and cigars with and without filters.

The term "area of desired permeability to air" is intended to mean a region in the wrapping having an intentional increased porosity, which is generally formed by inserting a perforation (one or more rows of holes) in the wrapping material. When the smokable article is smoked, secondary air is drawn in through this area, which is located at the mouth end of the article, which secondary air mixes with the tobacco smoke. The proportions of nicotine and condensate in the smoke can be modified by the quantity of secondary air mixed with the smoke. Since, recently, the values for nicotine and condensate are indicated on the sales packaging for smokable articles, it must be ensured that the values stated are maintained, which can be ensured inter alia due to the fact that the proportion of secondary air mixed with the smoke does not fall below a predetermined value.However, this makes checking of the permeability to air of the said area necessary, which should appropriately take place on the finished smokable article, because possible modifications of this area during the production of the article can only be monitored on the finished article.

The checking of wrappings of rod-like smokable articles is generally known, for which reason one produces a pressure drop in various ways between the inner space of the article surrounded by the wrapping and a space outside the wrapping and the pressure drop produced is monitored. Faults, for example holes in the wrapping, result in a reduction of the pressure drop, so that by means of a threshold value member, it is possible to monitor articles with a permeability to air of the wrapping above a limit value and to remove the latter from further processing (packing). The known checking devices are able to monitor reliably articles whereof the permeability to air of the wrapping varies from a predetermined value corresponding to the permeability to air of a hole having a diameter of one millimetre.The reliable monitoring of smaller deviations causes problems, because disturbance variables not to be modified, such as sealing problems at the time of checking, changes in the tobacco density and so on adulterate the checking signals. However, the permeability to air of the area of desired permeability to air of the wrapping to be checked is below that of a hole having a diameter of one millimetre and maintenance of the latter, i.e. monitoring when a tolerance of + 2% is exceeded, is expected.

The object of the invention is to check the wrapping of rod-like smokable articles as they are conveyed at right-angles to their axes on the one hand for undesirable permeability to air and on the other hand for the maintenance of a desired permeability to air in a certain area of the wrapping.

This object is fulfilled according to the invention due to the fact that each article is subjected to a first checking operation by forming a first pressure differential and forming a first checking signal, an upper limit value being fixed for the permeability to air of the wrapping and a checked article being considered as in order when the checking signal is below the upper limit value and that the articles are subjected to a second checking operation with maximum sensitivity in the region of the area of desired permeability to air by forming a second pressure drop and forming a second checking signal, changes of the second checking signal being monitored. As afore-mentioned, accurate monitoring of slight variations of the permeability to air of a wrapping, such as are intended to be ascertained in the second checking operation, causes problems.If it is sufficient to obtain a so-called trend indication for checking the area of desired permeability to air of the wrappings, then currently known checking arrangements can be used for the second checking operation if, according to one embodiment of the invention, a second checking signal corresponding to the average permeability to air of the area of desired permeability to air is formed for several articles which are checked in a predetermined time interval.

The term "time interval" is intended to mean both the natural time lapse as well as an artificial time lapse determined by one machine cycle for example. On the other hand, in recent times, it has been possible to reduce the effect of disturbance variables on the formation of a checking signal with recently developed checking devices.

Thus, in a further embodiment of the invention, a second checking signal can also be formed for each individual article. As was mentioned at the beginning, in the case of the smokable articles under consideration, it is important that the permeability to air of the wrapping material in the area of desired permeability to air does not fall below a predetermined minimum value.

Therefore, according to a further feature of the invention, for the second checking operation, it may suffice to fix only a lower limit value for the permeability to air of the wrapping in the area of desired permeability to air and to consider a checked article as in order if the second checking signal is above the lower limit value.

If, as provided according to one embodiment of the invention, the articles are subjected to the first checking operation in a first conveying section and to the second checking operation in a second conveying section of the path, then in the first checking operation, the first pressure drop can be formed at least over the major part of the wrapping including the area of desired permeability to air, so that during this first checking operation, it is also possible to monitor excessive permeability to air of the wrapping in the area of desired permeability to air.On the other hand, during the first checking operation, the first pressure drop may also be formed only over the major part of the wrapping excluding the area of desired permeability to air, so that during this checking operation, solely monitoring for faults in the wrapping outside the area of desired permeability to air takes place. Then, during the second checking operation, the second pressure drop is formed exclusively in the region of the area of desired permeability to air, so that a checking signal formed in this way is free from disturbance variables from the remaining regions of the article.However, the type of first checking operation described last and the type of second checking operation described hereafter facilitate a variation of the checking method, in that the articles are subjected to the first and second checking operation simultaneously in one conveying section of the path. Faulty smokable articles, i.e. those whose wrapping comprises excessive permeability to air, or, however, inadequate permeability to air of the wrapping in the region of the area of desired permeability to air, can be removed from further processing, in that a fault signal is formed when the checking signal is outside the fixed limit values and the fault signal controls the ejection of the checked faulty article.

The afore-mentioned arrangement, which serves in particular for carrying out the aforedescribed method is characterised in that a first checking device is provided which is constructed to form a first pressure drop between the space inside and the space outside the wrapping and the measuring arrangement of which comprises a signal transmitter for a signal emitted when the permeability to air of the wrapping is above an upper limit value and that a second checking device is provided whose maximum sensitivity is in the region of the area of desired permeability to air of the wrapping, which is constructed to form a second pressure drop between the space inside and the space outside the wrapping and whose measuring arrangement comprises means for monitoring changes in the permeability to air of the wrappings.A so-called trend indication for the permeability to air of the wrapping in the area of desired permeability to air is achieved with an arrangement in which the measuring arrangement of the second checking device comprises a device for adding checking signals emanating from several articles over predetermined time intervals and means for monitoring changes of the added checking signals or of a signal formed from the latter. If it is necessary to provide individual monitoring of articles whose wrapping in the area of desired permeability to air has a permeability to air varying from a predetermined range of tolerance then according to a further feature of the invention, the measuring arrangement of the second checking device is constructed to form individual checking signals for each article. For monitoring articles whose wrapping in the area of desired permeability to air has inadequate permeability to air, it is provided according to a further embodiment of the invention that the measuring arrangement of the second checking device comprises a signal transmitter for a signal emitted when the permeability to air of the wrapping is below a lower limit value. The two checking devices may be located one behind the other on the checking conveyor, whereby the first checking device can be constructed to form a first pressure drop at least over the major part of the wrapping including the area of desired permeability to air, or however, for forming a first pressure drop at least over the major part of the wrapping excluding the area of desired permeability to air.The preceding or subsequent second checking device is constructed to form a second pressure drop exclusively in the region of the area of desired permeability to air.

However, the first and second checking device can be located side-by-side on the checking conveyor. The measuring arrangements respectively comprise a pneumatic/electrical measuring transformer as well as a threshold value member as signal transmitter and they are connected to a control device for removing articles with a fault in the wrapping, from their feed path.

The invention is described in detail hereafter with reference to the drawings showing several embodiments: Figure 1 shows a filter attachment machine for producing filter cigarettes, diagrammatically, Figure 2 is a cutaway view of a checking drum of the filter attachment machine of Figure 1, in section, Figure 3 is a section through the part of the checking drum shown in figure 2, on line III-III, Figure 4 is a checking circuit diagram with two similar checking devices located one behind the other, for monitoring faults in the wrapping of smokable articles for the checking drum of figures 2 and 3, Figure 5 shows a variation of the checking circuit diagram of figure 4 with two similar checking devices located side-by-side Figure 6 shows a variation of the checking circuit diagram of figure 4 with two checking devices which are not similar, located one behind the other.

Figure 1 shows diagrammatically a filter attachment machine of the MAX S type of Hauni-Werke, Hamburg, Bergedorf. A feed drum 1 transfers the cigarettes produced on a cigarette production machine to two grading drums 2, which re-arrange the cigarettes supplied in staggered manner and supply them to an assembly drum 3 in rows of two with a gap between the cigarettes. The filter rods pass from a magazine 4 to a cutter drum 6, are cut by two circular cutters 7 to form filter plugs of double length, re-arranged on a grading drum 8, moved by a shifter drum 9 to form a row of plugs located one behind the other and deposited by an accelerator drum 11 in the gaps in the cigarette rows on the assembly drum 3. The cigarette/filter/cigarette groups are moved together, so that they lie side-by-side. They are then received by a transfer drum 12.A tipping paper strip 13 is withdrawn from a tipping paper reel 14 by means of a withdrawal roller 16. The tipping paper strip 13 is guided around a pretreater 17 comprising a sharp edge, glued by a glueing device 18 and cut on a tipping roller 19 by a cutter drum 21. The cut tipping paper pieces are stuck to the cigarettes filter groups on the transfer drum 12 and rolled around the cigarettes/filter groups on a rolling drum 22 by means of a roll hand 23. The finished groups of double filter cigarettes are transferred by way of a drying drum 24 to a cutting drum 26 and made into individual filter cigarettes on the latter by cutting centrally through the filter plug, faulty filter cigarettes being simultaneously ejected.A turning device 29 co-operating with a transfer drum 2 and a collecting drum 28 turns one row of filter cigarettes and simultaneously transfers them into the unturned row of filter cigarettes travelling by way of the transfer drum 27 and the collecting drum 28.

The filter cigarettes pass by way of a checking drum 31 to an ejection drum 32, on which the heads of the filter cigarettes are also scanned before the ejection operation. A catcher drum 34 co-operating with a brake drum 33 deposits the filter cigarettes on a catcher belt 36. The construction of the checking drum 31 constructed as a checking conveyor is shown in figures 2 and 3. In principle, all known checking devices, which check the wrapping of rod-like smokable articles pneumatically, can be used after alterations or completions carried out according to this invention. One checking device which requires little constructional alterations for the present invention is described for example in the Applicant's German Offenlegungsschrift 2.324.055 or the corresponding U.S.

Patent 3.948.084. Since constructional details of such a checking device are not the subject of this invention, only the present diagrammatic illustration has been selected for illustrating the invention A drum body 42 composed of three parts 38, 39 and 41 is mounted to rotate on a hollow shaft 37. Discs 44 provided with recesses 43 are attached to the part 39 on the end face, which discs 44 form holders for filter cigarettes Z. The part 39 comprises groove-like chambers 46, which are divided into partial chambers 46a and 46b by a cross piece 47 likewise provided with a recess 43 in a region of the filter F of the filter cigarettes Z adjacent a connecting point between the tobacco rod T and filter F. The tipping paper pieces B of the filter cigarettes Z have an area of desired permeability to air, which in the present example is formed by a row of holes L.The latter may already be contained in the tipping paper, or, however, may have been introduced into the tipping paper pieces B during production of the filter cigarettes, for example during the rolling operation, in known manner. Sealing means (second sealing means) in the form of a stationary cover plate 48 are provided between the discs 44, which cover plate closes-off the partial chambers 46a and 46b temporarily, as they rotate, apart from small gaps. An air supply 49 is provided as the means for forming different pressures in the partial chambers 46a and 46b.

For this, the hollow shaft 37 is divided by an annular wall 51 into two chambers 52a and 52b, which are connected to a pressure source as shown in the checking circuit diagrams of figures 4 and 5. The chambers 52a and 52b respectively comprise connection means in the form of a control slot 53a, 53b, by which the chambers 52a and 52b can be connected to the partial chambers 46a, 46b by channels 54a, 54b associated therewith, in the drum body 39.

To build up a pressure inside the wrappings of the filter cigarettes Z (figure 6) and/or for connection to a measuring arrangement monitoring pressure differences, sealing means (first sealing means) in the form of a disc 56 are associated with the drum body 42 on one side, which disc is a component of the part 38 of the drum body 42. The disc 56 comprises bores 57 aligning with the recesses 43 in the disc 44. A control ring 61 mounted on a machine wall 58, with connection means in the form of a control slot 62, is associated with the disc 56. On the other side of the drum body 42, sealing means (first sealing means) able to be controlled in the direction of the double arrow 63, in the form of tubes 66 provided with bores 64 are associated with the recesses 43 in the disc 44, which tubes are mounted on a disc 67 which is a component of the part 41 of the drum body 42.A control ring 68 attached to a hollow shaft 37 is associated with the disc 67 and comprises connection means in the form of a control slot 69, which likewise serves for connection to a pressure source and/or a measuring arrangement monitoing pressure differences.

From the checking circuit diagram of figure 4, it can be seen that two checking devices 71a and 71b are associated with the checking drum 31 shown in figures 2 and 3, which is facilitated by the fact that the control slots 62 and 69 of the control rings 61, 68 are respectively shorter than the spacing of the filter cigarettes Z on the checking drum 31 and are staggered by one or more spacings, so that the tubes 66 seal the filter cigarettes Z at the filter end only when the control slot 62 aligns with the filter cigarettes and the disc 56 seals the ends of the tobacco rod T only when the control slot 69 aligns with the filter cigarettes F.The control slots 53a and 53b of the chambers 52a, 52b of the hollow shaft 37 (figure 2) are also arranged in a corresponding staggered manner so that a pressure source 76 (source of reduced pressure) is connected in succession to the partial chambers 46a and 46b by way of a pipe 87, which divides into pipes 87a and 87b, which respectively comprise a control valve 88a, 88b and a pressure measuring device 89a, 89b and which open into the chambers 52a, 52b. In this case, the control valves 88a and 88b are adjusted such that a considerably higher reduced pressure is produced in the partial chamber 46b than in the partial chamber 46a.A pipe 82a is connected to the aforesaid control slot 62, which pipe comprises a restrictor 83a and connected to which, before this restrictor 83a are a slow device 84a for measuring pressure, for example a capsule-type pressure gauge and a measuring arrangement 86a monitoring pressure differences. The aforesaid control slot 69 is connected to a pipe 82b which comprises a restrictor 83b, in which case, before the latter, a slow device 84b for measuring pressure and a measuring arrangement 86b monitoring pressure differences are connected to the pipe 83b. The measuring arrangements 86a and 86b are identical in construction and consist of a pneumatic/electrical measuring transformer 91a, 91b, for example as described in the Applicant's U.S.Patent Specification 3.412.856, subsequent threshold value members 92a, 92b with associated reference value transmitters 94a, 94b and AND-gates 98a, 98b, which apart from being connected to the preceding threshold value members 92a, 92b, are connected to a timing element 99. The threshold value member 92a represents a signal transmitter for a signal emitted when the permeability to air of the wrappings of the filter cigarettes F is above an upper limit value, in that it emits an output signal when the output signal of the measuring transformer 91a supplied to the latter exceeds the corresponding pre-set reference value of the reference value transmitter 94a.The threshold value member 92b represents a signal transmitter for a signal emitted when the permeability to air of the wrapping is below a lower limit value, in that it emits an output signal when the output signal of the measuring transformer 91b supplied to the latter falls below the corresponding pre-set reference value of the reference value transmitter 94b. The pressure measuring devices 84a and 84b are means for monitoring changes in the permeability to air of the wrappings, which on account of their sluggishness, within the scope of the invention, represent a device for adding checking signals emanating from several articles, over predetermined time intervals and represent means for monitoring changes in the added checking signals. The sluggishness of the pressure measuring devices 84a and 84b represents a time constant, so that their reading at a predetermined machine speed forms a mean value of the permeability to air of the wrappings of a certain number of filter cigarettes F. The measuring arrangements 86a and 86b, which serve for evaluating the checking signals emanating from individual filter cigarettes F, are connected by the outputs of their ANDgates 98a and 98b by an OR-gate 97 to a shift register 101, which is driven by a timing element 99. One output of the shift register 101 is connected to a control device 102 for removing articles with faults in the wrapping from their feed path. The control device 102 comprises an amplifier 103 and an electromagnetic valve 104, which is located in a pipe 108 connecting a source of compressed air 106 to an ejection nozzle 107.This ejection nozzle 107 is associated with the ejection drum 32 of the filter attachment machine shown in figure 1.

The method of operation of the aforedescribed checking device is as follows: The chambers 46 respectively located below the cover plate 48 are supplied with reduced pressure by the pressure source 76, in which case according to the arrangement of figure 4, the partial chambers 46a are firstly connected to the source of reduced pressure 76 and then the partial chambers 46b. In the preceding checking device 71a, air is drawn through the pipe 82a and the checking slot 62a into the inside of the filter cigarette Z, in which case the flow of air depends on the permeability to air of the wrapping surrounding the tobacco rod T of the filter cigarette Z.The measuring transformer 91a sends an electrical signal corresponding to the pressure prevailing in the pipe 82a continuously to the threshold value member 92a, which sends an output signal to the ANDgate 98a, when the signal sent to the latter exceeds the signal of the reference value transmitter 94a. By way of the AND-gate 98a and the timing element 99, evaluation of the checking signals takes place at the correct checking instant, namely when a filter cigarette Z is connected to the control slot 62. If at this instant, the AND-gate 98a sends a signal to the OR-gate 97, then the filter cigarette Z checked at this time has excessive permeability to air of its wrapping in the region of the tobacco rod T.

A signal is then sent by the OR-gate 97 to the shift register 101.

In the checking device 71b, as a result of the reduced pressure in the partial chamber 46b, air is drawn in through the pipe 82b, the control slot 69 into the filter F and through the holes L in the tipping paper pieces B. The measuring transformer 91b sends an electrical signal corresponding to the respective pressure prevailing in the pipe 82b continuously to the threshold value member 92b, which sends an output signal to the AND-gate 98b when the signal supplied to the latter falls below the signal of the reference value transmitter 94b. This evaluation of the checking signals takes place as afore-described by way of the AND-gate 98b and the timing element 99, at the correct instant.If at the said instant, the AND-gate 98b sends a signal to the OR-gate 97, then the filter cigarette Z checked at this time has inadequate permeability to air of the tipping paper piece B, i.e. a perforation (holes L) which is not in order. The output signal of the AND-gate 98b sent to the OR-gate 97 causes a signal to be sent to the shift register 101. The average permeability to air of the wrappings of several filter cigarettes Z for the region of the tobacco rods T can be read from the slow device 84a for measuring pressure and for the region of the filter F, in particular for the area of desired permeability to air (holes L in the tipping paper pieces B) from the slow device 84b for measuring pressure.Individual evaluation of the checking signals by way of the measuring arrangement 86a and 86b facilitates removal of filter cigarettes with a faulty wrapping from further processing, namely in that a signal supplied to the shift register 101 is moved in the latter in synchronism with the conveying movement of the respectively associated filter cigarette F, so that if the respective filter cigarette F reaches the ejection point of the ejection drum 32, the electromagnetic valve 104 is activated in synchronism, due to which ajet of air leaves the ejection nozzle 107 and blows the filter cigarette F from the ejection drum 32.

A variation of the checking device 71a is shown in dot-dash line, in which, during the first checking operation, not only the partial chamber 46a, but also the partial chamber 46b is supplied with reduced pressure. With a circuit of this type, in addition to the wrapping of the tobacco rod T, the tipping paper piece B of a filter cigarette F can also be monitored for excessive permeability to air, which can be produced by a faulty perforation (holes L).

As described, the two checking devices 71a and 71b should be associated with a single checking drum one behind the other. However, two checking drums can also be provided in a satisfactory manner, the latter comprising only one checking device. In contrast to the latter, figure 5 shows a variation of the checking circuit diagram, in which the two checking devices are located side-by-side, i.e. the two checking operations ot different sections ot wrappings ot the filter cigarettes are carried out simultaneously.

For this, on the checking drum according to figures 2 and 3, the control slots 62 and 69 as well as the control slots 53a and 53b, as illustrated, are arranged to align with each other. Since, as aforesaid, the only difference with respect to the checking circuit diagram of figure 4 consists in that the two checking devices are now located side-by-side, apart from the spatially different arrangement, all parts shown in figure 5 which are identical to those of figure 4 are given the same reference numerals, increased by 100 and are not described again in detail. Consequently, the method of operation is also identical to that of the checking circuit diagram of figure 4, with the difference that the two checking operations take place simul- taneously. Reference may therefore be made to the description of figure 4 as regards the method of operation.

Figure 6 shows a variation of the checking circuit diagram of figure 4 with two checking devices 271a and 271b arranged one behind the other, which in contrast to the diagram of figure 4 check the filter cigarettes Z in different ways and in particular the checking device 271a operates by blowing air through and the checking device 271b operates by inflation. The checking drum 31 shown in figures 2 and 3 is adapted to this checking circuit diagram, in that the control rings 61 and 68 respectively comprise two control slots 62, 69 located one behind the other, so that two checking stations are formed.

The checking device 271a is constructed such that checking air passes by way of a pipe 287a, which branches fran a pipe 287 connected to the pressure side of a pressure source 276 and which contains a control valve 288a, a device 289a for measuring preliminary pressure and a restrictor 281a, to the filter cigarette Z. The checking air flows through the filter cigarette Z and leaves the latter through a pipe 282a, which comprises a restrictor 283a, before which a slow device 284a for measuring pressure and a measuring arrangement 286a monitoring pressure differences are connected. The measuring arrangement 286a contains a pneumatic/ electrical measuring transformer 291a, which is connected at the output side to a signal transmitter in the form of a threshold value member 292a.Associated with the threshold value member 292a is a reference value transmitter 294a for an upper limit value, the threshold value member 292a being connected such that it emits an output signal when the output signal of the measuring transformer 291a exceeds the signal of the reference value transmitter 294a.

At the output side, the threshold value member 292a is connected to one input of an AND-gate 298a, whose other input is connected to a timing element 299. At the output side, the AND-gate 298a is connected to a shift register 301, which is driven by the timing element 299 and whose output is connected to a control device 302 for removing articles with faults in the wrapping from their feed path. The control device 302 comprises an amplifier 303 and an electromagnetic valve 304, which is located in a pipe 308 connecting a source of compressed air 306 to an ejection nozzle 307. The ejection nozzle 307 is associated with the ejection drum 32 of the filter attachment machine shown in figure 1.

In the checking device 271b, checking air is introduced into the two end faces of the filter cigarette Z by a pipe 287b likewise branching from the pipe 287, which pipe 287b branches into pipes 287b' and 287b". The pipe 287b comprises a control valve 288b and a restrictor 281b. The pipe branch 287b" comprises a restrictor 285b, after which is located a measuring arrangement 286b. The measuring arrangement 286b consists of means for monitoring changes in the permeability to air of the wrappings of filter cigarettes Z in the form of a slow device 284b for measuring pressure, for example a capsule-type pressure gauge.The sluggishness of the device 284b for measuring pressure represents a time constant, so that with a predetermined production or throughout capacity of the filter attachment machine, its reading represents a mean value for a certain number of checked filter cigarettes Z. Within the scope of the invention, in- the simplest form, the device 284b for measuring pressure represents a device for adding checking signals emanating from several articles, over predetermined time intervals, its reading representing means for monitoring changes in the added checking signals. Naturally, in place of the device 284b for measuring pressure, an electronic device for forming a means value, operating exactly according to the machine cycle can be used, which is supplied by a pneumatic/ electrical measuring transformer.The restrictor 285b in the branch pipe 287b" brings about asymmetrical sensitivity of the checking device 271b, so that the values indicated by the device 294b for measuring pressure primarily emanate from fluctuations of the permeability to air of the tipping paper strip B of the filter cigarettes Z provided with holes L.

On the other hand, in the checking device 271a, the permeability to air of the entire wrapping material of the filter cigarettes Z is checked, in which case filter cigarettes Z with excessive permeability to air of their wrapping are excluded from further processing by the measuring arrangement 286a whose construction is already known from the afore-described embodiment and the control device 302.

If one drum is provided for the checking devices 271a and 271b shown in figure 6, then it is possible to seal-off regions of the wrappings.

which are not to be monitored with the respective checking device, by surrounding the latter mechanically, by means of controlled valves, as shown in the Applicant's U.S. Patent Specification 3.339.402, on each drum. Thus, in the checking device 271a due to an approriate construction of the flaps, it is possible to close-off the holes L in the wrapping material, so that the entire wrapping is checked, with the exception of the region containing the holes L and in the checking device 271b, it is possible to surround the entire wrapping with the exception of the region comprising the holes L, so that in this case only the holes L are checked.

The advantage of the invention consists in that whilst essentially maintaining the known and proven checking principles with the additional measures according to the invention, it is possible to monitor both faults in the wrapping, i.e. an excessive permeability to air of the wrapping in general, as well as faults in an area of desired permeability to air of the wrapping, i.e. when a predetermined minimum permeability to air of this area is not reached, although both possibilities of faults must be monitored in very different ranges of tolerance.

Attention is directed to our copending Application Nos. Serial No. 1 596 391 Serial No. 1 596 393 49286/77 and 49288/77 which relate to similar subject-matter.

WHAT WE CLAIM IS: 1. Method for checking rod-like smokable articles for faulty wrappings, which have an

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. checking drum 31 shown in figures 2 and 3 is adapted to this checking circuit diagram, in that the control rings 61 and 68 respectively comprise two control slots 62, 69 located one behind the other, so that two checking stations are formed. The checking device 271a is constructed such that checking air passes by way of a pipe 287a, which branches fran a pipe 287 connected to the pressure side of a pressure source 276 and which contains a control valve 288a, a device 289a for measuring preliminary pressure and a restrictor 281a, to the filter cigarette Z. The checking air flows through the filter cigarette Z and leaves the latter through a pipe 282a, which comprises a restrictor 283a, before which a slow device 284a for measuring pressure and a measuring arrangement 286a monitoring pressure differences are connected. The measuring arrangement 286a contains a pneumatic/ electrical measuring transformer 291a, which is connected at the output side to a signal transmitter in the form of a threshold value member 292a.Associated with the threshold value member 292a is a reference value transmitter 294a for an upper limit value, the threshold value member 292a being connected such that it emits an output signal when the output signal of the measuring transformer 291a exceeds the signal of the reference value transmitter 294a. At the output side, the threshold value member 292a is connected to one input of an AND-gate 298a, whose other input is connected to a timing element 299. At the output side, the AND-gate 298a is connected to a shift register 301, which is driven by the timing element 299 and whose output is connected to a control device 302 for removing articles with faults in the wrapping from their feed path. The control device 302 comprises an amplifier 303 and an electromagnetic valve 304, which is located in a pipe 308 connecting a source of compressed air 306 to an ejection nozzle 307. The ejection nozzle 307 is associated with the ejection drum 32 of the filter attachment machine shown in figure 1. In the checking device 271b, checking air is introduced into the two end faces of the filter cigarette Z by a pipe 287b likewise branching from the pipe 287, which pipe 287b branches into pipes 287b' and 287b". The pipe 287b comprises a control valve 288b and a restrictor 281b. The pipe branch 287b" comprises a restrictor 285b, after which is located a measuring arrangement 286b. The measuring arrangement 286b consists of means for monitoring changes in the permeability to air of the wrappings of filter cigarettes Z in the form of a slow device 284b for measuring pressure, for example a capsule-type pressure gauge.The sluggishness of the device 284b for measuring pressure represents a time constant, so that with a predetermined production or throughout capacity of the filter attachment machine, its reading represents a mean value for a certain number of checked filter cigarettes Z. Within the scope of the invention, in- the simplest form, the device 284b for measuring pressure represents a device for adding checking signals emanating from several articles, over predetermined time intervals, its reading representing means for monitoring changes in the added checking signals. Naturally, in place of the device 284b for measuring pressure, an electronic device for forming a means value, operating exactly according to the machine cycle can be used, which is supplied by a pneumatic/ electrical measuring transformer.The restrictor 285b in the branch pipe 287b" brings about asymmetrical sensitivity of the checking device 271b, so that the values indicated by the device 294b for measuring pressure primarily emanate from fluctuations of the permeability to air of the tipping paper strip B of the filter cigarettes Z provided with holes L. On the other hand, in the checking device 271a, the permeability to air of the entire wrapping material of the filter cigarettes Z is checked, in which case filter cigarettes Z with excessive permeability to air of their wrapping are excluded from further processing by the measuring arrangement 286a whose construction is already known from the afore-described embodiment and the control device 302. If one drum is provided for the checking devices 271a and 271b shown in figure 6, then it is possible to seal-off regions of the wrappings. which are not to be monitored with the respective checking device, by surrounding the latter mechanically, by means of controlled valves, as shown in the Applicant's U.S. Patent Specification 3.339.402, on each drum. Thus, in the checking device 271a due to an approriate construction of the flaps, it is possible to close-off the holes L in the wrapping material, so that the entire wrapping is checked, with the exception of the region containing the holes L and in the checking device 271b, it is possible to surround the entire wrapping with the exception of the region comprising the holes L, so that in this case only the holes L are checked. The advantage of the invention consists in that whilst essentially maintaining the known and proven checking principles with the additional measures according to the invention, it is possible to monitor both faults in the wrapping, i.e. an excessive permeability to air of the wrapping in general, as well as faults in an area of desired permeability to air of the wrapping, i.e. when a predetermined minimum permeability to air of this area is not reached, although both possibilities of faults must be monitored in very different ranges of tolerance. Attention is directed to our copending Application Nos. Serial No. 1 596 391 Serial No. 1 596 393 49286/77 and 49288/77 which relate to similar subject-matter. WHAT WE CLAIM IS:

1. Method for checking rod-like smokable articles for faulty wrappings, which have an

area of desired permeability to air, as they are conveyed at right-angles to their axes along a predetermined path, by forming a pressure differential between a space comprising a filling surrounded by the wrapping and a space outside the wrapping and by forming a checking signal dependent on the permeability to air of the wrapping, wherein each article is subjected to a first checking operation by forming a first pressure differential and forming a first checking signal, an upper limit value being fixed for the permeability to air of the wrapping and a checked article being considered as in order when the checking signal is below the upper limit value and the articles are subjected to a second checking operation with maximum sensitivity in the region of the area of desired permeability to air by forming a second pressure differential and forming a second checking signal, changes in the second checking signal being monitored.

2. Method according to claim 1, wherein for several articles which are checked in a predetermined time interval, a second checking signal is formed corresponding to the average permeability to air of the area of desired permeability to air.

3. Method according to claim 1, wherein a second checking signal is formed for each individual article.

4. Method according to one or more of the preceding claims, wherein for the second checking operation, a lower limit value for the permeability to air of the wrapping in the area of desired permeability to air is fixed and a checked article is considered as in order when the second checking signal is above the lower limit value.

5. Method according to one or more of the preceding claims, wherein the articles are subjected to the first checking operation in a first conveying section and to the second checking operation in a second conveying section of the path.

6. Method according to claim 5, wherein in the first checking operation, the first pressure drop is formed at least over the major part of the wrappings including the area of desired permeability to air.

7. Method according to claim 5, wherein in the first checking operation, the first pressure drop is formed at least over the major part of the wrappings excluding the area of desired permeability to air.

8. Method according to one or more of the preceding claims, wherein in the second checking operation, the second pressure drop is formed exclusively in the region of the area of desired permeability to air.

9. Method according to claim 7 and/or 8, wherein the articles are subjected to the first and second checking operation simultaneously in one conveying section of the path.

10. Method according to one or more of the preceding claims, wherein a fault signal is formed when the checking signal is outside the fixed limit values and that the fault signal controls the ejection of the checked faulty article.

11. Arrangement for checking rod-like smokable articles for faulty wrappings, which have an area of desired permeability to air, with a rotating checking conveyor comprising holders for retaining the articles and with a checking device which comprises sealing means for the temporary separation of a space comprising a filling, surrounded by the wrapping, from a space outside the wrapping of each article, connection means which connect one of the two spaces to a pressure source and connection means which connect one of the two spaces to a measuring arrangement monitoring pressure differences, wherein a first-checking device is provided, which is constructed to form a first pressure differential between the space inside and the space outside the wrapping and whose measuring arrangement comprises a signal transmitter for a signal emitted when the permeability to air of the wrapping is above an upper limit value and a second checking device is provided, whose maximum sensitivity is in the region of the area of desired permeability to air of the wrapping, which is constructed to form a second pressure differential between the space inside and the space outside the wrapping and whose measuring arrangement comprises means for monitoring changes in the permeability to air of the wrappings.

12. Arrangement according to claim 11, wherein the measuring arrangement of the second checking device comprises a device for adding checking signals emanating from several articles, over predetermined time intervals and comprises means for monitoring changes of the added checking signals or of a signal formed from the latter.

13. Arrangement according to claim 11, wherein the measuring arrangement of the second checking device is constructed to form individual checking signals for each article.

14. Arrangement according to one or more of the preceding claims 11 to 13, wherein the measuring arrangement of the second checking device comprises a signal transmitter for a signal emitted when the permeability to air of the wrapping is below a lower limit value.

15. Arrangement according to one or more of the preceding claims 1 to 14, wherein the two checking devices are located one behind the other on the checking conveyor.

16. Arrangement according to claim 15, wherein the first checking device is constructed to form a first pressure drop at least over the major part of the wrapping including the area of desired permeability to air.

17. Arrangement according to claim 15, wherein the first checking device is constructed to form a first pressure drop at least over the major part of the wrapping, excluding the area of desired permeability to air.

18. Arrangement according to one or more of the preceding claims 11 to 17, wherein the second checking device is constructed to form a second pressure drop exclusively in the region of the area of desired permeability to air.

19. Arrangement according to claim 17 and/ or 18, wherein the first and second checking device are located side-by-side on the checking conveyor.

20. Arrangement according to one or more of the preceding claims 11 to 19, wherein the measuring arrangements comprise a pneumatic/ electrical measuring transformer as well as a threshold value member as signal transmitter.

21. Arrangement according to one or more of the preceding claims 11 to 20, wherein the measuring arrangements are connected to a control device for removing articles with a fault in the wrapping from their feed path.

22. Method for checking rod-like smokable articles for faulty wrappings, substantially as herein described with reference to the accompanying drawings.

23. Arrangement for checking rod-like smokable articles for faulty wrappings, substantially as herein described with reference to and as illustrated in the accompanying draw ings.