GB2117220A - Method and apparatus for making filter rod sections - Google Patents

Abstract

Filter rods are made by (1) forming a continuous filter rod which comprises a substantially impermeable outer layer (2) rendering selected portions of the outer layer more permeable (3) sub-dividing the filter rod. The increase in permeability can be achieved by making of holes in or a mere reduction of the thickness of selected portions of the outer layer.

Description

SPECIFICATION Method and apparatus for making filter rod sections The present invention relates to a method and machine for making filter rod sections which can be united with tobacco rods to form therewith filter cigarettes, cigarillos, cigars or analogous rodshaped filter-tipped smokers' products. More particularly, the invention relates to improvements in a method and machine for the making of filter rod sections by subdivision of a continuous filter rod wherein a preferably rod-like filler of filter material is surrounded by an outer layer which forms a tube around the filter material and normally exhibits a pronounced resistance to the flow of gases therethrough.

It is well known to produce filter rod sections of desired axial length by repeatedly severing the leader of an axially advancing filter rod wherein a web of cigarette paper, imitation cork or a like wrapping material is draped around a rod-like filler consisting of acetate fibers and/or other filter material and the web exhibits a rather pronounced resistance to the flow of gases therethrough so as to prevent uncontrolled mixing of air with tobacco smoke flowing through the filter mouthpiece of a filter-tipped smokers' product wherein the mouthpiece forms part of a filter rod section.

In the manufacture of so-called ventilated filter cigarettes, cigars or cigarillos (hereinafter referred to as cigarettes with the understanding, however, that the same applies for cigars, cigarillos and analogous rod-shaped smokers' products), atmospheric air must be allowed to flow through the wrapper of the tobacco-containing portion or through the tubular outer layer of the filter mouthpiece in order to mix with the column of tobacco smoke. The admixture of cool atmospheric air is believed to reduce the presumably deleterious effects of tobacco smoke upon the health of the smoker. The paths for the inflow of atmospheric air into the tobaccocontaining portions and/or into the filter mouthpieces of filter cigarettes can be established by piercing or burning holes in the wrappers of the tobacco-containing portions and/or in the tubular outer layers of the mouthpieces.Alternatively, perforations may be made in the so-called uniting bands which are used to connect tobaccocontaining portions with filter mouthpieces in filter tipping machines. Of course, and since the uniting bands are convoluted around the filter mouthpieces of filter cigarettes, the making of perforations in the uniting bands is to no avail if the outer layers of the mouthpieces are not permeable to air. Such permeability is normally achieved by making the outer layers of the filter mouthpiece from an air-permeable material.This is not the best solution because the permeability of the material of the outer layers can vary from zone to zone and, moreover, highly air-permeable wrapping material is often too weak to allow for the making of firm filter mouthpieces which can stand the treatment preceding and including their assembly with tobacco-containing portions to form filter cigarettes of unit length or multiple unit length.

One feature of the invention resides in the provision of a method of producing filter rod sections. The method comprises the steps of forming a continuous filter rod having an elongated (preferably rod-like) filler of filter material and a tubular outer layer exhibiting a rather pronounced resistance to the flow of gases therethrough, subdividing the filter rod into filter rod sections of predetermined length (e.g., of two, four or six times unit length), and increasing the permeability of selected portions of the outer layer prior to the subdividing step, i.e., before the sections are severed from the rod. The permeability increasing step may but need not necessarily include making holes in the selected portions of the outer layer.Such selected portions can extend transversely of the longitudinal direction of the filter rod; if the permeability increasing step includes making holes, such holes can form rows extending circumferentially of the filler and at right angles to the longitudinal direction of the filter rod. The method preferably further comprises the step of moving the filter rod lengthwise (axially), at least in the course of the subdividing or severing step. Thus, the aforementioned rows of holes are then disposed in planes which are at least substantially normal to the direction of lengthwise movement of the filter rod.

The forming step can comprise draping the filler into a continuous web of wrapping material which constitutes the outer layer of the resulting filter rod and exhibits the aforementioned pronounced resistance to the flow of gases therethrough. The permeability increasing step can include weakening the resistance of selected portions of the web of wrapping material prior to the subdividing step and, if desired, prior to the draping step.

The permeability increasing step can include mechanically weakening the resistance of selected portions of the outer layer to the flow of gases therethrough. Such mechanical weakening can involve making cuts or slits in selected portions of the outer layer, puncturing selected portions of the outer layer, punching holes in (blanking) selected portions of the outer layer, removing at least some material from selected portions of the outer layer (e.g., by grinding and/or milling whereby the grinding or milling operation can involve the making of holes or a mere reduction of the thickness of selected portions of the outer layer to thereby reduce the resistance of the thus weakened portions to the flow of gases therethrough), making holes by spark generation and/or exposing selected portions of the outer layer to high-energy radiation (e.g., to one or more laser beams).

The selected portions are preferably disposed at predetermined distances from the axial ends of the filter rod sections, and the outer layer of each filter rod section preferably includes at least one portion which is less resistant to the flow of gases than the remainder of the outer layer. For example, if each filter rod section is of six times unit length, its outer layer has at least six portions whose resistance to the flow of gases has been reduced in accordance with the method of the present invention so that the outer layer of each and every filter mouthpiece which is obtained in response to further subdivision of a filter rod section will have a portion that allows for penetration of atmospheric air into the column of tobacco smoke that flows through the filler while the respective filter cigarette, cigar or cigarillo is lighted.Each filter plug is united with a tobacco-containing rod by a uniting band (e.g., a piece of tipping paper consisting of paper, artificial cork or the like) which is preferably provided with at least one zone allowing atmospheric air to flow therethrough, and such zone is in register with the selected portion of the outer layer of the respective filter mouthpiece.

Another feature of the invention resides in the provision of a machine for the production of filter rod sections. The machine comprises means for forming a continuous filter rod having an elongated filler of filter material and a tubular outer layer which surrounds the filler and exhibits a pronounced resistance to the flow of gases therethrough. The machine further comprises means for moving the filter rod lengthwise along a predetermined path, means for subdividing the filter rod into filter rod sections of predetermined length in a predetermined portion of the path, and means for increasing the permeability of selected portions of the outer layer ahead of the predetermined portion of the path.The forming means can include a source of filter material (e.g., a bale consisting of a tow of filamentary filter material, such as acetate fibers), means for withdrawing filter material from the source and for converting the withdrawn filter material into the filler, a source of supply of wrapping material (e.g., a bobbin containing a supply of convoluted cigarette paper) which exhibits the aforementioned pronounced resistance to the flow of gases therethrough, means for withdrawing wrapping material from the source of supply, and means for draping the withdrawn wrapping material around the filler so that the thus draped wrapping material constitutes the outer layer of the resulting filter rod.

The permeability increasing means can include means for making holes in selected portions of the outer layer. The selected portions of the outer layer can extend transversely of the direction of lengthwise movement of the filter rod. For example, the permeability increasing means can include means for making in the selected portions of the outer layer rows of holes extending circumferentially of the filler and at least substantially at right angles to the direction of lengthwise movement of the filter rod. The permeability increasing means can be placed adjacent to the path of movement of the aforementioned wrapping material to the draping means so that selected portions of the wrapping material exhibit a less pronounced resistance to the flow of gases therethrough even before they are applied around the filler.

The permeability increasing means can include means for mechanically reducing the resistance to the flow of gases through selected portions of the outer layer of the filter rod. Such means for mechanically reducing the resistance to the flow of gases can include means for severing the selected portions of the outer layer, means for piercing the selected portions of the outer layer, punching means for blanking the selected portions of the outer layer (i.e., for removing circular, oval, rectangular, square, star-shaped or otherwise configurated portions of the material of the outer layer), grinding means for merely reducing the thickness of selected portions of the outer layer and/or for making holes therein, and/or milling means for merely reducing the thickness of selected portions of the outer layer and/or for making holes therein.Still further, the means for increasing the permeability of selected portions of the outer layer can include at least one source of radiation, e.g., one or more lasers, or means for generating sparks which burn holes in selected portions of the outer layer.

The permeability increasing means is preferably arranged to increase the permeability of at least one selected portion of the outer layer of each and every filter rod section at a predetermined distance from the axial ends of the respective section. This renders it possible to place such selected portions into accurate register with airpermeable portions of adhesive-coated uniting bands which are used to connect the filter rod sections (or portions of filter rod sections) with tobacco rods to form therewith filter cigarettes, cigars or cigarillos.As a rule, the sections which are severed from the leader of the running filter rod are of multiple unit length so that each thereof is subsequently subdivided into two or more filter plugs or filter mouthpieces the outer layer of each of which should exhibit at least one portion whose resistance to the flow of gases therethrough is less pronounced than the resistance of the remaining portion or portions of the respective outer layer.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved machine itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

FIG. 1 is a schematic partly elevational and partly sectional view of a filter rod making machine wherein the outer layer of the filter rod is treated in accordance with one embodiment of the invention; FIG. 2 is an enlarged view of a portion of a web of wrapping material which is to form the tubular outer layer of the filter rod and is treated in accordance with the method of the invention so as to exhibit transversely extending rows of polygonal perforations; FIG. 3 is a side elevational view of a filter rod section of six times unit length whose tubular outer layer is made of a piece of wrapping material of the type shown in FIG. 2;; FIG. 4 is a side elevational view of a partly finished filter cigarette of double unit length which employs a filter mouthpiece of double unit length constituting one-third of the filter rod section shown in FIG. 3, and further showing a perforated adhesive-coated uniting band which is about to be convoluted around the mouthpiece and around the adjacent portions of two plain cigarettes of unit length; FIG. 5 is an elevational view of two discrete filter cigarettes of unit length which arp obtained in response to halving of a filter cigarette whose constituents are shown in FIG. 4; FIG. 6 is an elevational view of a device which can be used in the machine of FIG. 1 to increase the permeability of selected portions of the outer layer of the filter rod; and FIG. 7 shows a portion of a web of wrapping material subsequent to treatment by the device of FIG. 6.

The filter rod making machine which is shown in FIG. 1 comprises a first unit 1 which serves to treat a tow 4 of filamentary filter material (e.g., acetate fibers) and to convert such tow into a filler 4f, and a second unit 2 which serves to convert the filler 4f and a continuous web 27 of cigarette paper, imitation cork or other suitable wrapping material into a continuous filter rod 31 wherein the filler 4f is surrounded by a tubular outer layer consisting of the material of the web 27. The machine of FIG. 1 is similar to those known as KDF manufactured by the assignee of the present application.

The unit 1 comprises a source 6A containing a supply (e.g., a bale 6) of filamentary filter material in the form of the aforementioned tow 4 which is withdrawn from the source 6A (such source can constitute a suitable receptacle or a platform for the base 6) by a pair of advancing rolls 3 the lower of which is driven at a variable speed by a transmission 1 6 whose ratio can be adjusted by a motor 17. On their way from the bale 6 to the nip of the advancing rolls 3, successive increments of the tow 4 pass through a first banding device 7, thereupon around a guide roll 5 and thereafter through a second banding device 8. The purpose of the banding devices 7 and 8 is to loosen the tow 4 so that the individual filaments can be readily separated from one another during further travel of the tow through the unit 1.Each of the banding devices 7 and 8 can comprise a nozzle (note the nozzle 7a) which has a plurality of orifices serving to discharge jets of compressed gas against the adjacent increments of the tow which advance between such nozzle and a back support (note the back support 7b). The details of the banding devices 7 and 8 form no part of the present invention.

The advancing rolls 3 are followed by two additional pairs (9 and 11) of advancing rolls. The peripheral speed of the advancing rolls 9 exceeds the peripheral speed of the advancing rolls 3 so that the tow 4 is stretched in the region between the rolls 3 and 9, e.g., to the elastic limit of the material of its filaments. This results in further loosening of the tow so that all or nearly ail of its filaments are exposed not later than during travel across the space between the nips of the advancing rolls 9 and 11. Such space accommodates a spraying device 12 which serves to apply an atomized liquid plasticizer to the separated filaments of the tow 4.One each of the two pairs of rolls 9 and 11 is preferably formed with circumferentially extending peripheral grooves and the other roll of each of these pairs of rolls is preferably formed with an elastically deformable rim having a smooth peripheral surface. Such configuration of the rolls 9 and 11 contributes to desirable separation or loosening of the filaments which form the tow 4 while the filaments advance through the plasticizer-applying spraying device 12.

The three pairs of rolls 3, 9 and 11 receive motion from the main prime mover 14 (e.g., a variable-speed electric motor) of the filter rod making machine through the medium of suitable belt or chain drives 1 5, 1 5a and 4 sub. The lower roll of the pair of rolls 9 drives the input element of the aforementioned transmission 1 6 as well as a cylindrical brush 22 which forms part of the spraying device 12. The torque transmitting connection between the lower roll 9 and the brush 22 includes an endless belt or chain conveyor 15c.

The spraying device 1 2 further comprises a vessel 1 8 for a supply 13 of plasticizer, a withdrawing roller 21 which dips into the supply 13 to deliver a film of plasticizer into the range of bristles on the rotating cylindrical brush 22, and a discrete prime mover 1 9 (e.g., a variable-speed electric motor) which drives the withdrawing roller 21. The bristles of the brush 22 propel droplets of atomized plasticizer against the underside of the spread-out tow 4 between the pairs of rolls 9 and 11. The plasticizer which penetrates through the interstices of the flattened tow 4 is intercepted by the underside of a plate 20 above the path for the tow 4, and the thus intercepted plasticizer is wiped off and entrained by the tow toward the nip of the rolls 11. The purpose of the plasticizer is to bond the neighboring filaments of the tow 4 to each other so that, when the tow is converted into the filler 4f, the latter defines a myriad of minute paths for the flow of tobacco smoke toward the mouth of the smoker.

The means for converting the thus treated tow 4 into the filler 4f comprises a gathering horn 23 which can be said to form part of the second unit 2 and whose outlet directs successive increments of the rod-like filler onto the adhesive-coated upper side of the web 27 of wrapping material on the upper reach of an endless garniture belt 28 driven by the prime mover 14. The source of supply of the web 27 is a bobbin 24 which is installed in or on the frame 30 of the filter rod making machine and from which the web 27 is continuously withdrawn by a pair of advancing rolls 41. One side of the web 27 is thereupon coated with adhesive during travel along a conventional paster 26 located downstream of a second pair of advancing rolls 43 for the web 27, and the web is thereupon caused to advance toward and onto the upper reach of the garniture belt 28 below the filler 4f of filter material.The frame 30 further supports a set of guide rollers 44, 46, 47, 48 and 49 for the web 27.

During travel with the upper reach of the belt 28, the web 27 and the filler 4f are caused to advance through a wrapping mechanism 29 which drapes the web 27 around the filler 4f so that the web is converted into the tubular outer layer of the resulting filter rod 31. The belt 28 advances the rod 31 lengthwise along a sealer 32 which causes the adhesive between the overlapping marginal portions of the draped web 27 to set so that the seam of the tubular outer layer can stand the stresses to which the rod 31 is subjected during repeated severing of its leader in a severing device 33, e.g., a conventional cutoff of the type used in cigarette making and like machines. The sealer 32 can heat or cool the seam of the tubular outer layer of the rod 31, depending on the nature of adhesive which is applied by the paster 26.

The cutoff 33 subdivides the rod 31 into a file of discrete filter rod sections 34 of six times unit length, and successive sections 34 of such file are accelerated by a rapidly rotating cam 36 so that each section is propelled into a discrete peripheral flute of a drum-shaped row-forming conveyor 37.

The latter converts the file of filter rod sections 34 into a row wherein the sections move sideways, and successive sections of the thus obtained row are deposited on the upper reach of a belt or chain conveyor 38 which delivers the filter rod sections to a curing station (e.g., into a reservoir of the type known as RESY which is manufactured by the assignee of the present application), into storage or directly to a processing machine, e.g., to the magazine of a filter tipping machine (such as MAX or MAX S manufactured by the assignee of the present application). Reference may be had to commonly owned U.S. Pat. No. 4,323,082 granted April 6, 1982 to Helms et al. which describes and shows a MAX S filter tipping machine. A filter rod making machine which is somewhat similar to the machine of FIG. 1 is disclosed in commonly owned U.S.Pat. No.

3,971,695 granted July 1976 to Biock.

The web 27 of wrapping material can be made of paper, imitation cork or the like. As a rule, the resistance of the web 27 to the penetration of gases therethrough is rather pronounced. Selected portions of this web are treated on their way toward the upper reach of the garniture belt 28 so that their permeability is increased and they permit atmospheric air to penetrate into the filler 4f when the filter rod sections 34 are subdivided into filter mouthpieces of unit length which are united with tobacco rods to form therewith filter cigarettes, cigars or cigarillos of unit length or multiple unit length.The means for increasing the permeability of selected portions of the web 27 (so that the outer layer of each unit length of each of the filter rod sections 34 contains at least one portion whose permeability is more pronounced than the permeability of the web 27 on the core of the bobbin 24) comprises a perforating device 42 which is installed in or on the frame 30 between the advancing rolls 41 and 43 to provide the selected portions of the web 27 with transversely extending rows of perforations 51 of the type shown in FIGS. 2 and 3. Each of these perforations has a polygonal (e.g., square or rectangular) outline, and the distribution of the aforementioned rows is such that each filter rod section 34 of six times unit length is formed with six rows a, b, c, d, e and fof perforations 51.This means that, when a filter rod section 34 is subdivided into six discrete filter mouthpieces of unit length, the tubular outer layer of each such mouthpiece is formed with a row of, for example, four equidistant perforations 51. The rows a to fextend at right angles to the direction (arrow F in FIG. 2) of lengthwise movement of the web 27 from the bobbin 24 to the wrapping mechanism 29 and of lengthwise movement of the rod 31 from the wrapping mechanism 29 toward the cutoff 33.

Each of the rows a to fforms a ring around the respective portion of the filler 4f in the filter rod 31.

FIG. 2 shows that the rows of perforations 51 do not extend into the marginal portions 27a and 27b of the web 27, i.e., into those portions which form the seam of the tubular outer layer of the filter rod 31. This ensures that the seam is not weakened and can withstand the stresses which arise during subdivision of the rod 31 into discrete sections 34 of six times unit length.

If the filter rod sections 34 are thereupon admitted into a filter tipping machine of the aforementioned type (MAX or MAX S), each thereof is first subdivided into three filter plugs 34a, 34b and 34c (see FIG. 3) by severing each section 34 in two parallel planes 34A and 34B.

The tubular outer layer of each of the filter plugs 34a, 34b, 34c then contains two rows (a and b, c and d, e and fl of perforations 51. In the next step, each of the filter plugs 34a-34c is placed between a pair of tobacco rods and is connected to such tobacco rods by a uniting band V, e.g., a piece of so-called tipping paper. This is shown in FIG. 4 for the filter plug 34a which is placed between two plain cigarettes Z of unit length. That side of the uniting band V which faces the observer of FIG. 4 is coated with adhesive, and such uniting band is thereupon convoluted around the filter plug 34a and around the adjacent inner end portions of the plain cigarettes Z so that the components which are shown in FIG. 4 are assembled into a filter cigarette of double unit length.

The uniting band V is formed with two rows of perforations Va and Vb which can be formed by sparks, e.g., in a manner as disclosed in commonly owned U.S. Pat. No. 4,247,754 granted January 1981 to Baier and in commonly owned U.S. Pat. No. 4,320,773 granted March 23, 1982 to Pinck et al. The arrangement is such that the rows of perforations Va and Vb respectively register with the rows a and b of perforations in the outer layer of the filter plug 34a. To this end, the rows a to f of perforations 51 in the outer layer of each filter rod section 34 are formed at predetermined distances from the two axial ends of such filter rod section.The rows of perforations Va and Vb are formed in predetermined portions of the uniting bands V so that, and in view of the accuracy with which a MAX or MAX S machine can position the uniting bands V relative to the groups of coaxial rodshaped articles (such as Z, 34a, Z of FIG. 4) which are to be converted into filter cigarettes of double unit length, the rows of perforations Va and Vb invariably register with the rows of perforations 51 in the outer layers of the respective filter plugs.

It will be readily appreciated that the application of adhesive to one side of each uniting band V (actually to one side of the continuous strip of tipping paper which is converted into a succession of discrete uniting bands V) preferably takes place in such a way that the rows Va and Vb of perforations are not coated with adhesive. The manner in which adhesive paste can be applied to one side of a running strip of tipping paper is disclosed, for example, in commonly owned U.S.

Pat. No. 4,249,547 granted February 10, 1981 to Hinzmann, in commonly owned U.S. Pat. No.

4,262,680 granted April21, 1981 to Hinzmann, and in commonly owned U.S. Pat. No. 4,282,889 granted August 11, 1981 to Dahigrün.

In lieu of resorting to an apparatus which makes the rows Va and Vb of perforations by spark discharge, it is equally possible to use apparatus which perforate the strip of tipping paper by beams of high-energy radiation, particularly laser beams. Apparatus for making holes in webs of tipping paper, cigarette paper or the like are disclosed in commonly owned U.S.

Pat. No. 4,121,595 granted October 1978 to Heitmann et al., in commonly owned U.S. Pat. No.

4,240,448 granted December 23, 1980 to Heitmann et al., in commonly owned U.S. Pat. No.

4,249,545 granted February 10, 1981 to Gretz et al., in commonly owned U.S. Pat. No.

4,265,254 granted May 5, 1981 to Koch et al., in commonly owned U.S. Pat. No. 4,281,670 granted August 4, 1981 to Heitmann et al., and in commonly owned U.S. Pat. No. 4,301,816 granted November 1 981 to Wahle et al.

The step of convoluting the uniting band V around the respective filter plug of double unit length and around the adjacent inner end portions of the respective plain cigarettes Z is carried out in a so-called rolling unit of the filter tipping machine. Suitable rolling units are disclosed in commonly owned U.S. Pat. No. 3,483,873 granted December 16, 1969 to Hinzmann and in commonly owned U.S. Pat. No. 3,527,234 granted September 8, 1970 to Hinzmann. The resulting filter cigarette of double unit length is thereupon severed in the plane 34C (see FIG. 4) to yield two filter cigarettes FZ of unit length (see FIG. 5). Each cigarette FZ contains a plain cigarette Z, one-half of the filter plug 34a (i.e., a filter mouthpiece of unit length) and one half (V/2) of the uniting band V.Also, each of the cigarettes FZ has a ventilating zone which is formed by the perforations Va or Vb and the respective row (a or b) of perforations 51 which are in register with the perforations Va or Vb.

The ventilating zones are ring-shaped, i.e., they surround the fillers of the respective filter mouthpieces of unit length, and are disposed at a preselected (optimum) distance from the free end of the respective mouthpiece of unit length. This ensures that the ventilating zone is not likely to be obstructed by the lips of the smoker and/or by the fingers of the hand which holds the filter cigarette FZ.

As mentioned above, the filter rod 31 can be subdivided into sections which are longer or shorter than the sections 34, e.g., into sections of two or four times unit length. It is further clear that the perforating device 42 can provide the web 27 with perforations of circular, oval, stellate or other shape without departing from the spirit of the invention. Moreover, such perforations can be formed by slitting, piercing, milling, grinding, punching or other suitable instrumentalities, depending on the desired configuration and/or distribution of perforations.Still further, the perforating device 42 can be designed in such a way that the tubular outer layer of each filter rod section of six times unit length can be formed with, for example, twelve or eighteen rows of perforations 51, i.e., each mouthpiece of unit length can have a tubular outer layer with two or more circumferentially extending ring-shaped rows of perforations at a desired distance from the axial ends of the mouthpiece. This depends on the desired distribution and/or permeability of the ventilating zones. It is further clear that the paster 26 is or can be designed in such a way that it does not apply adhesive to the selected portions of the web 27, namely, to the portions whose permeability to gases is increased during travel through the perforating device 42.In many filter rod making machines, the paster 26 is constructed and assembled in such a way that it provides one side of the web 27 with one or more longitudinally extending strips or films of adhesive, e.g., a web adhesive or a hotmelt. This is customary when the tow 4 consists of acetate fibers. Such adhesive strip or strips serve to bond the overlapping marginal portions 27a, 27b of the web 27 to one another as well as to bond certain portions of the inner side of the tubular outer layer of the filter rod 31 to the adjacent fibers of the filler 4f.If the paster 26 is to avoid the application of adhesive to the aforementioned selected portions of the one side of the running web 27, that roller of the paster whose peripheral surface applies adhesive to the web is provided with raised portions which together form a pattern adapted to apply to the web 27 one or more interrupted longitudinally extending strips of adhesive; the interruptions are disposed at the aforementioned selected locations where the tools or implements of the device 42 increase the permeability of the material of the web 27. Reference may be had again to the aforementioned commonly owned U.S. Pat. No.

4,249,547 to Hinzmann.

In accordance with a presently preferred embodiment of the invention, the device 42 can be designed to pierce or to remove material from the running web 27 of wrapping material. In other words, the device 42 need not merely reduce the thickness (and thereby increase the permeability) of selected portions of the web 27 but actually makes holes, passages or perforations all the way through the material of the web. For example, the device 42 can contain a first driven roller (patrix) with several files of punching or like material removing tools which extend circumferentially of and project from the periphery of the first roller, and a second roller (matrix).The first roller carries a file of circumferentially extending tools for each perforation of a row (a, b, c, d, e or fl of perforations to be formed in the web 27, and the configuration of cutting edges of the tools determines the shape and the dimensions of perforations. All of the tools may but need not have identically configurated and/or dimensioned cutting edges, i.e., each of the rows a to fof perforations 51 can contain two or more different types of perforations. The spacing between the tools in and one of the circumferentially extending files of tools on the first roller determines the spacing between the neighboring rows of perforations in the web 27, and the number of files of tools determines the number of perforations in each of the rows a to f.

The second roller of the just discussed perforating device is formed with recesses or sockets for the tools of the first roller. As the two rollers rotate in opposite directions, the tools penetrate through the material of the web 27 which is caused to advance through the nip of the two rollers, and the tools thereupon enter the registering recesses or sockets of the second roller. The second roller can be replaced with an endless metallic band with apertures which replace the recesses or sockets of the second roller and into which the tools of the first roller penetrate subsequent to penetration through the material of the web 27.An advantage of such metallic band is that it can be driven by the first roller in response to penetration of tools into its apertures as well as that the surfaces bounding the apertures of the band can cooperate with the tools to sever the material of the web, e.g., to fully remove pieces of the material of the web which are partially removed by the tools and would continue to adhere to the web in the absence of a combined shearing action which is performed by the tools of the first roller in cooperation with the band. If a second roller is used, it need not be provided with recesses or sockets if its peripheral portion is made of an elastomeric material which yields in response to engagement by the oncoming tools of the first roller.The forces which are required to make holes in the web 27 are very small so that the cutting edges of the tools need not strike against a rigid anvil in order to sever the material of the web. Thus, the elastic material at the periphery of the second roller can constitute a yieldable anvil which cooperates with the tools to ensure the making of holes or perforations having a predictable size and/or shape. The blanked out fragments of the material of the web 27 can be brushed away or removed by a pneumatic device, e.g., a blower or a suction generating device.

The aforediscussed first roller of the perforating device can resemble the roller 187a, and the second roller can resemble the roller 1 89a in FIG. 6 of the commonly owned U.S. Pat. No.

4,193,409 granted March 18, 1980 to Wahle et al. FIG. 6 of the just mentioned patent also shows punching tools 1 88a which can remove material from a running web 1 3. The disclosure of each of the aforementioned patents is incorporated herein by preference.

The just discussed device for increasing the permeability of selected portions of the web 27 can be replaced with a device which forms incisions in or punctures the material of the web.

A device which can form incisions in a tubular body is disclosed, for example, in commonly owned U.S. Pat. No. 3,817,158 granted June 18, 1 974 to Wahle et al. A device which can pierce the tubular outer layer of a rod-shaped article, or which can pierce a web of wrapping material, is disclosed, for example, in the aforementioned commonly owned U.S. Pat. No. 4,193,409 to Wahle et al.

As mentioned above, the device which increases the permeability of selected portions of the tubular outer layer of the filter rod need not actually perforate the material of the web. For example, such device can include means for grinding away or for milling away some of the material of the web without penetrating through the entire web. An apparatus or device which can treat a web of wrapping material in such a way can comprise a set of protuberances over which the web is caused to pass and which are adjacent to rotary, reciprocatory or otherwise movable material removing (e.g., grinding or milling) tools which remove some material from the web portion that is in register with the respective protuberance. The distribution of protuberances can be the same as that of the selected portions of the web. Such apparatus can be converted from one which merely weakens selected portions of the web to one which actually removes material all the way through the web, for example, to provide the web with holes of the type shown at 51 in FIG. 2.

It is equally within the purview of the invention to perforate the web 27 subsequent to conversion of this web into the tubular outer layer of the finished filter rod 31. For example, the device 42 of FIG. 1 can be installed between the sealer 32 and the cutoff 33, i.e., again ahead of that portion of the path for the web 27 and rod 31 where the rod is subdivided into a succession of discrete filter rod sections 34. The device which is installed between the parts 32 and 33 can include mechanical perforating tools in the form of needles, punches, milling tools, grinding tools or the like.If the selected portions of the tubular outer layer of the rod 31 are to be formed with holes by resort to needles or the like, the needles can be mounted on rotary carriers whose peripheral speed deviates slightly from the speed of lengthwise movement of the filter rod 31 so that the needles not only puncture the web but also enlarge the resulting holes as a result of their movement relative to the filter rod. For example, a perforating device which is installed between the sealer 32 and the cutoff 33 can include several driven wheels which rotate about axes extending tangentially of the filter rod 31 and at right angles to the axis of the rod and are angularly offset with reference to one another, as considered in the circumferential direction of the rod.Such a device is also capable of providing the outer layer of the rod 31 with annuli of perforations which form rows extending circumferentially of the filler 4f. If the needles of the just described perforating device are replaced with punches or other material removing tools, the speed of the tools can match the speed of lengthwise movement of the rod 31.

If the device which increases the permeability of selected portions of the web 27 or of the tubular outer layer of the filter rod employs rotating tools (such as milling tools), the holders for such tools must merely move back and forth, i.e., into and from engagement with the web or with the outer layer.

If the means for reducing the resistance of selected portions of the tubular outer layer of the rod 31 to the flow of gases therethrough employs one or more laser beams, such laser beams can be distributed around the circumference of the rod, for example, in a manner as disclosed in the aforementioned U.S. Pat. No. 4,121,595. This patent further shows that it is not necessary to provide two or more lasers, i.e., that one can resort to beam splitters and analogous devices to provide the web or the tubular outer layer with several rows of perforations (as considered in the longitudinal direction of the web or rod) with resort to a single laser.

It is even possible to employ a device which makes perforations by directing against the web, or against the tubular outer layer of the rod, a series of extremely thin liquid jets at elevated or very elevated pressure. The liquid (e.g., water) which impinges upon the web evaporates practically instantaneously so that it does not leave any stains on the remainder of the web.

At least some of the aforedescribed devices for reducing the resistance to penetration of gases through the outer layer of the filter rod can be used to perforate or to reduce the thickness of the outer layer of a filter rod wherein the outer layer does not constitute a discrete web of cigarette paper or the like which is draped around the filler of filter material but rather wherein the outer layer consists of the same material as the filler and is converted into a tube as a result of suitable thermal treatment or the like. Reference may be had to the aforementioned commonly owned U.S.

Pat. No. 4,301,816 to Wahle et al.; this patent discloses filters whose outer layers are not formed by discrete wrapping material but rather by suitable treatment of the outermost region of the filler of filter material. For example, a device which employs one or more lasers, a device which uses jets of highly compressed liquid, or a mechanical perforating device can be used with advantage to make holes in the outer layers of filter rods wherein the material of the outer layers is the same as that of the filler and the outer layer normally exhibits a pronounced resistance to the penetration of gases therethrough.

FIG. 6 illustrates the details of a device which can constitute or form part of the device 42 shown in FIG. 1. This device comprises a first roller 62 which is driven in a clockwise direction, as shown in FIG. 6, and whose peripheral surface is engaged by successive increments of the web 27 advancing beyond the nip of the advancing rolls 41. The peripheral surface of the roller 62 is formed with suitably distributed recesses or sockets 61, and the shaft 62a of this roller is driven by the main prime mover 14 of the filter rod making machine through the medium of a belt or chain drive 15d which can also drive the garniture belt 28.

The roller 62 cooperates with a second roller 64 which has radially outwardly extending protuberances 63 distributed in such a way that they penetrate into the oncoming recesses 61 of the first roller 62 when the shaft 64a of the second roller is driven at a speed such that the peripheral speed of the roller 64 matches that of the roller 62. The web 27 is trained first over a portion of the roller 62 and thereupon over a portion of the roller 64 on its way toward the nip of the second advancing rolls 43. In the embodiment of FIG. 6, the roller 62 merely serves to guide the web 27 to the roller 64 which cooperates with a rotating milling tool 66 having teeth 66a serving to remove material from thole portions of the web 27 which are caused to bulge outwardly by the protuberances 63 of the second roller 64.The shaft 66b of the tool 66 is preferably driven at a speed which is several times the speed of lengthwise movement of the web 27. The teeth 66a can merely remove some material from the bulging portions of the web 27, or they can actually make holes (e.g., elongated rectangular perforations 51' of the type shown in FIG. 7) in selected portions of the web 27. In the embodiment of FIG. 6, the roller 64 carries several rows of protuberances 63, and such rows extend at right angles to the plane of the drawing. Also, the milling tool 66 has several annuli of teeth 66a, one annulus for each perforation 51' of the row a, b, c or shown in FIG. 7.

The reference character 67 denotes an intercepting device which gathers the material that is removed from the web 27 by the teeth 66a, and the contents of the intercepting device 67 are evacuated by suction, by compressed air or by gravity, either at regular intervals or when the need arises. The intercepting device 67 can define a channel extending at right angles to the plane of FIG. 6 and having one of its ends connected to the intake of a suction fan.

FIG. 7 again shows that the rows a to d of perforations 51' need not extend all the way to the marginal portions 27a and 27b of the web 27.

This ensures that the seam which is formed when the web 27 is draped around the filler 4f.is devoid of perforations and is not weakened in the regions of the transversely extending rows of perforations 51'. In fact, it suffices if only one of the marginal portions 27a, 27b is devoid of perforations 51', namely, that marginal portion which overlies the other marginal portion when the web 27 is draped around the filler 4f. The non-perforated marginal portion (27a or 27b) of the web 27 is coated with adhesive during travel of the web 27 along the paster 26.

As mentioned above, the paster 26 can provide one side of the web 27 with several longitudinally extending strips of adhesive. One of the strips is used to form the seam between the overlapping marginal portions 27a and 27b, and the remaining strip or strips of adhesive are used to bond the respective portions of the web 27 to the outermost filaments of the filler 4f. This contributes to stability of the draped web (especially to its resistance to tearing) and of the filter rod and prevents the flow of larger streams of tobacco smoke along the internal surface of the draped web. As also mentioned hereinabove, the paster 26 is preferably designed to avoid the application of adhesive in the regions of the rows of perforations 51' in the web 27.One mode of applying adhesive to selected portions of a web of wrapping or like material for use in the tobacco processing industry is disclosed in the aforementioned commonly owned U.S. Pat. No.

4,282,889 to Dahigrün. The design of the rollershaped applicator of adhesive in the paster 26 can be such that the paster applies adhesive to each and every portion of one side of the web 27 except to those portions which are formed with the perforations 51', i.e., adhesive can also be applied to the webs between the perforations 51' of the rows a, b, c and d shown in FIG. 7.

If the milling tool 66 of FIG. 6 is replaced with a grinding wheel having several coaxial discs (one for each perforation 51' in a row of perforations in the web 27), the device of FIG. 6 can be used to make holes in, or to merely reduce the thickness of, selected portions of the web 27 by a grinding (in lieu of a milling) action.

Still further, the protuberances 63 can be replaced by punching tools with cutting edges which form perforations in those portions of the web 27 that advance through the nip of the rollers 62, 64. The tool 66 is then omitted or moved away from the roller 64 so that its teeth 66a cannot reach the web 27.

Claims (41)

1. A method of producing filter rod sections, comprising the steps of forming a continuous filter rod having an elongated filler of filter material and a tubular outer layer exhibiting a pronounced resistance to the flow of gases therethrough; subdividing the filter rod into sections of predetermined axial length; and increasing the permeability of selected portions of the outer layer prior to said subdividing step.

2. The method of claim 1, wherein said permeability increasing step includes making holes in the selected portions of the outer layer.

3. The method of claim 1, wherein said selected portions extend transversely of the longitudinal direction of the filter rod.

4. The method of claim 3, wherein said permeability increasing step includes making rows of holes in said selected portions of the outer layer.

5. The method of claim 3, further comprising the step of moving the rod axially in the course of said subdividing step.

6. The method of claim 1, wherein the selected portions of the outer layer constitute annuli extending circumferentially of the filler.

7. The method of claim 6, wherein said permeability increasing step includes making rows of holes in said annuli and further comprising the step of moving the rod at right angles to said rows.

8. The method of claim 1, wherein said forming step comprises draping the filler into a continuous web of wrapping material which constitutes said outer layer and exhibits said pronounced resistance to the flow of gases therethrough, said permeability increasing step including weakening the resistance of said selected portions of the web prior to said subdividing step.

9. The method of claim 1 , wherein said permeability increasing step includes mechanically weakening the resistance of said selected portions of the outer layer to the flow of gases therethrough.

10. The method of claim 1, wherein said permeability increasing step includes making cuts in said selected portions of the outer layer.

11. The method of claim 1, wherein said permeability increasing step comprises puncturing said selected portions of the outer layer.

12. The method of claim 1, wherein said permeability increasing step comprises punching holes in said selected portions of the outer layer.

13. The method of claim 1, wherein said permeability increasing step includes removing at least some material from the selected portions of the outer layer.

14. The method of claim 13, wherein said removing step includes grinding the selected portions of the outer layer.

1 5. The method of claim 13, wherein said removing step includes milling the selected portions of the outer layer.

1 6. The method of claim 13, wherein said removing step includes weakening the material of the outer layer at said selected portions so as to reduce the resistance of such selected portions to the flow of gases therethrough.

17. The method of claim 1, wherein said permeability increasing step includes exposing the selected portions of the outer layer to high-energy radiation.

18. The method of claim 17, wherein said radiation is emitted by one or more lasers.

1 9. The method of claim 1, wherein at least one of said selected portions is provided in the outer layer on each section at a predetermined distance from the axial ends of the respective section, and further comprising surrounding at least a part of each section with a uniting band having a region of pronounced permeability in at least partial register with the selected portion of the outer layer of the respective section.

20. The method of claim 19, wherein said surrounding step includes connecting each filter rod section with at least one tobacco rod, end-toend, through the medium of the respective uniting band.

21. In a machine for the production of filter rod sections, the combination of means for forming a continuous filter rod having an elongated filler of filter material and a tubular outer layer surrounding the filler and exhibiting a pronounced resistance to the flow of gases therethrough; means for moving the filter rod lengthwise along a predetermined path; means for subdividing said rod into sections of predetermined axial length in a predetermined portion of said path; and means for increasing the permeability of selected portions of the outer layer ahead of said predetermined portion of said path.

22. The combination of claim 21, wherein said permeability increasing means includes means for making holes in said selected portions of the outer layer.

23. The combination of claim 21, wherein said forming means includes a source of filter material, means for withdrawing filter material from said source and for converting the withdrawn filter material into said filler, a source of supply of wrapping material exhibiting said pronounced resistance to the flow of gases therethrough, means for withdrawing wrapping material from said source of supply, and means for draping the withdrawn wrapping material around said filler so that the thus draped material constitutes the outer layer of the resulting filter rod.

24. The combination of claim 21, wherein the selected portions of the outer layer extend transversely of the direction of lengthwise movement of the filter rod.

25. The combination of claim 21, wherein said permeability increasing means includes means for making in said selected portions rows of holes extending circumferentially of the filler and at least substantially at right angles to the direction of lengthwise movement of the filter rod.

26. The combination of claim 21, wherein said permeability increasing means includes a perforating device having means for making holes in the selected portions of the outer layer.

27. The combination of claim 21, wherein said forming means includes a source of supply of wrapping material, means for withdrawing the wrapping material from said source of supply and means for draping the withdrawn wrapping material around the filler in a second portion of said path ahead of said predetermined portion so that the draped wrapping material constitutes the outer layer of the resulting filter rod, said permeability increasing means being arranged to increase the permeability of selected portions of the wrapping material ahead of said second portion of said path.

28. The combination of claim 21 , wherein said permeability increasing means includes means for mechanically reducing the resistance to the flow of gases through the selected portions of the outer layer.

29. The combination of claim 28, wherein said means for mechanically reducing the resistance to the flow of gases includes means for severing said selected portions of the outer layer.

30. The combination of claim 28, wherein said means for mechanically reducing the resistance to the flow of gases includes means for piercing said selected portions of the outer layer.

31. The combination of claim 28, wherein said means for mechanically reducing the resistance to the flow of gases includes punching means for blanking said selected portions of the outer layer.

32. The combination of claim 28, wherein said means for mechanically reducing the resistance to the flow of gases includes grinding means for reducing the thickness of said selected portions of the outer layer.

33. The combination of claim 28, wherein said means for mechanically reducing the resistance to the flow of gases includes milling means for reducing the thickness of said selected portions of the outer layer.

34. The combination of claim 28, wherein said means for mechanically reducing the resistance to the flow of gases includes at least one grinding tool.

35. The combination of claim 28, wherein said means for mechanically reducing the resistance to the flow of gases includes at least one milling tool.

36. The combination of claim 21, wherein said permeability increasing means comprises at least one source of radiation.

37. The combination of claim 36, wherein said radiation source comprises at least one laser.

38. The combination of claim 21, wherein each of said sections has a first and a second end and said permeability increasing means is arranged to increase the permeability of at least one selected portion of the outer layer of each filter rod section at a predetermined distance from the end portions of the respective section.

39. The combination of claim 38, wherein each of said sections is of multiple unit length and said permeability increasing means includes means for increasing the permeability of a selected portion of the outer layer in each unit length of each of said sections.

40. A method of producing filter rod sections, substantially as herein described with reference to the accompanying drawings.

41. A machine for the production of filter rod sections, substantially as herein described with reference to and as illustrated in the accompanying drawings.