Abstract:
A web of air-permeable uniting band material for use in a filter tipping machine is advanced lengthwise by a first pair of driven rollers and a second pair of driven rollers, first through a magazine which is located between the two pairs of rollers, thereupon around a roller-shaped flanged adjustable braking device which is located upstream of the second pair of rollers, and around an adjustable curling device between the braking device and the second pair of rollers. The braking action is regulated for the purpose of subjecting the running web to a predictable curling action. This enhances the quality of filter cigarettes wherein the tobacco-containing and the filter material-containing parts are connected to each other by adhesive-coated uniting bands constituting sections of the thus treated web.

Description:
CROSS-REFERENCE TO RELATED CASES 
     This application claims the priority of commonly owned German patent application Serial No. 199 28 867.4 filed Jun. 24, 1999. The disclosure of the above-referenced German patent application, as well as that of each U.S. and foreign patent and patent application mentioned in the specification of the present application, is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to improvements in apparatus for transporting unwound webs of wrapping material, especially for smokers&#39; products, and more particularly too improvements in apparatus for treating running webs of paper, artificial cork or other flexible sheet material. Such webs are normally drawn off bobbins and can be utilized in filter tipping machines wherein plain cigarettes, cigars or cigarillos (hereinafter referred to as cigarettes) are assembled with filter rod sections to yield filter cigarettes of unit length or multiple unit length. 
     It is customary to advance a web of so-called tipping paper from a bobbin or another suitable source past a perforating unit which provides the running web with pores or the like in order to render the web permeable to gaseous fluids, i.e., to permit penetration of air into the column of tobacco smoke flowing from the lighted end of a filter cigarette, through the mouthpiece and into the mouth of a smoker. It is also customary to advance successive increments of the running web past (around) a so-called curling device which promotes the tendency of the web to yield uniting bands which can be readily converted into cylindrical or oval envelopes each of which surrounds the mouthpiece and the adjacent end portion of the tobacco-containing part of a plain cigarette. 
     The web treating action of the curling device is greatly influenced by the nature and/or extent of treatment of the running web ahead of the curling station. The quality of filter cigarettes containing convoluted uniting bands made of a properly or optimally curled web invariably exceeds the quality of filter cigarettes containing uniting bands which are obtained as a result of repeated severing of a poorly curled web of tipping paper. The web which is being advanced toward the curling station is engaged by one or more advancing or transporting devices which not only advance but also tension those successive increments of the running web which advance past the curling station. Moreover, the bobbin which supplies the web (i.e., from which the web is being unwound) is acted upon by a brake. 
     A curling device can be designed to exhibit a cylindrical surface provided with suction ports which attract succesive web portions or increments trained around a portion of the cylindrical surface. The quality of curling action furnished by such device is dependent upon the nature of treatment to which the running web is subjected upstream of the curling station. 
     Curling devices at least some of which can be put to use in the apparatus of the present invention are disclosed, for example, in U.S. Pat. No. 3,996,842 granted Dec. 14, 1976 to Klaus-Dieter Ehlich and Heinz-Christen Lorenzen for “APPARATUS FOR REDUCING AND EQUALIZING LOCALIZED STESSES IN RUNNING PAPER WEBS OR THE LIKE”. 
     OBJECTS OF THE INVENTION 
     An object of the invention is to provide a novel and improved apparatus for manipulating running strips, tapes or webs of a sheet material which is to be converted into cylindrical envelopes or the like, for example, in a tipping machine which serves to turn out filter cigarettes. 
     Another object of the invention is to provide a novel and improved apparatus which employs one or more so-called web curling or rolling devices. 
     A further object of the invention is to provide novel and improved means for treating a running web ahead or upstream of a curling device. 
     An additional object of the invention is to provide an apparatus which can be installed in or utilized in conjunction with existing filter tipping machines. 
     Still another object of the invention is to provide a novel and improved method of manipulating a running web of perforated uniting band material for use in filter tipping machines ahead of the web curling station. 
     A further object of the invention is to provide a novel and improved web braking and stressing device for use in the above outlined apparatus. 
     Another object of the invention is to provide a novel and improved combination of an adjustable web curling device and a web monitoring unit for use in the above outlined apparatus. 
     An additional object of the invention is to provide a novel and improved combination of at least one web curling device, adjusting means for the curling device, and means for advancing the web toward, past and beyond the curling device. 
     SUMMARY OF THE INVENTION 
     The invention is embodied in an apparatus for treating a running web of flexible sheet material, e.g., a permeable sheet material which has undergone treatment in an apparatus of the type shown in FIGS. 1 and 2 of U.S. Pat. No. 4,281,670 granted Aug. 4, 1981 to Uwe Heitmann et al. for “APPARATUS FOR INCREASING THE PERMEABILITY OF WRAPPING MATERIAL FOR ROD-SHAPED SMOKERS&#39; PRODUCTS”. The apparatus of the present invention comprises suitable means for advancing the web from a source (such as a bobbin or reel) in a predetermined direction along an elongated path; the advancing means can include a first advancing unit defining a first portion of the path and a second advancing unit defining a second portion of the path downstream of the first portion. The improved apparatus further comprises a magazine or an analogous storage facility defining a third portion of the path between the first and second portions, an adjustable suction-operated web braking device adjacent a fourth portion of the path between the third and second portions, and web curling means adjacent a fifth portion of the path between the fourth and second portions. 
     At least one of the first and second advancing units can comprise a pair of driven rollers which define a nip for the running web in the respective (first or second) portion of the path. 
     In accordance with a presently preferred embodiment, the magazine can be installed immediately downstream of the first port ion of the path and can include means for temporary storage of successive lengths of the running web in the form of one or more loops as well as means for varying the length of that portion of the running web which can be stored in the magazine. 
     The braking device can include means for applying to the web a variable braking force in the fourth portion of the path (i.e., upstream of the curling means), and means for adjusting the braking force. The force applying means can include a roller having a peripheral surface which contacts the web in the fourth portion of the path, and means for rotating the roller in a direction to move the peripheral surface of the roller in the fourth portion of the path counter to the (predetermined) direction of advancement of the web along its path. The arrangement can be such that the second advancing unit is set up to advance the web at a first speed whereas the means for rotating the roller of the braking device is arranged to move the peripheral surface of the roller in the fourth portion of the path at a second speed which is less than the first speed, e.g., at a second speed which is close to zero speed. The peripheral surface of the aforementioned roller of the force applying means can be provided with a plurality of suitably distributed ports, and the running web is trained over a first portion of such peripheral surface, i.e., a second portion of the peripheral surface is out of contact with the running web. The force applying means of the braking device can further include a suction generating device (e.g., a blower or fan having a suction intake) and means for connecting the suction generating device with ports which are provided in the first portion of the peripheral surface. 
     The just described web braking device can further comprise means for expelling impurities, if any, from the ports in the second portion of the peripheral surface of the roller forming part of the braking device. For example, the impurities expelling means can include a source of compressed gaseous fluid and means (such as axially parallel channels in the roller of the braking device) for connecting the source of compressed gaseous fluid with the ports in the second portion of the peripheral surface. 
     The roller of the braking device imparts to the fourth portion of the path an arcuate shape. 
     The apparatus can further comprise means for monitoring the tension upon the running web, particularly the tension which is generated by the second web advancing unit, and means for actuating the aforementioned adjusting means when the monitored tension is outside of a predetermined range. 
     The roller of the braking device can be provided with axially spaced-apart flanges flanking that portion of the web which is trained over the roller in the fourth portion of the path, namely over that portion of the roller which is provided with the aforementioned ports. 
     The improved apparatus can further embody that feature which is disclosed in the aforementioned &#39;842 patent to Ehlich e al., namely means for monitoring the running web to detect the splices which connect successive elongated sections of the web to each other. The apparatus can employ an adjustable curling means, and the latter is adjusted whenever a splice advances along the fifth portion of the path. The curling means can be designed in such a way that it is adjustable between an operative and an inoperative condition, and the splice detecting monitoring means can generate signals which render the curling means inoperative during advancement of detected splices along the fifth portion of the path for the running web. 
     The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved web treating apparatus itself, however, both as to its construction and the modes of assembling and operating the same, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic front elevational view of an apparatus which embodies one form of the present invention; 
     FIG. 2 is an enlarged side elevational view of a roller which forms part of the adjustable suction-operated web braking device in the apparatus of FIG. 1; 
     FIG. 3 is a transverse sectional view as seen in, the direction of arrows from the line B—B in FIG. 2; 
     FIG. 4 is a smaller-scale axial sectional view of the roller shown in FIGS. 2-3 and a fragmentary elevational view of certain other constituents of the braking device; and 
     FIG. 5 is a greatly enlarged axial sectional view of a filter cigarette embodying a uniting band forming part of a web which has undergone treatment in the apparatus of the present invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 shows an apparatus which serves to treat a running web consisting of so-called tipping paper and being adapted to be utilized in a filter tipping machine disclosed, for example, in FIGS. 1 and 2 of the aforementioned &#39;670 patent to Heitmann et al. The web  1  is caused to advance lengthwise, in the direction indicated by arrows  3 , by an advancing means including a first advancing unit  2  and a second advancing unit  17 . The advancing unit  2  of FIG. 1 comprises two driven rollers (one of these rollers can be driven by a variable-speed prime mover (not shown) to drive the other roller by way of the web  1  which advances through the nip of the two rollers) defining a first portion or section of the elongated path for the web. The advancing unit  2  can draw the web  1  from a suitable source, such as one of the bobbins or reels shown in FIG. 1 of the &#39;670 patent to Heitmann et al. 
     The porosity or permeability of the web  1  can be enhanced upstream of the first web advancing unit  2 , for example, by one or more laser beams as shown in FIG. 2 of the &#39;670 patent to Heitmann et al. The illustrated second advancing unit  17  has three rollers one of which can be driven by a motor, not shown, and the others of which can be driven by the one roller by way of the web  1  which is caused to advance through the nips of such rollers in the second portion of the path for the running web. 
     The apparatus of FIG. 1 further comprises a magazine  4  which defines a third portion of the path for the web  1  preferably immediately downstream of the nip of the rollers forming part of the first web advancing unit  2 . The magazine  4  includes a receptacle/reservoir  6  for an elongated looped portion of the running web  1 . The receptacle  6  includes an adjustable partition  9  which divides its interior into two chambers  7  and  8 . The chamber  7  serves to receive a loose loop  11  (e.g., about five meters) of web material. The length of the loop  11  is monitored by a photoelectronic sensor or detector  12 . The leader of the loop  11  leaves the chamber  7  and enters the chamber  8  through a relatively narrow passage or gate  13 ; this ensures that the web “quiets down” prior to reaching a combined braking and cleaning station accommodating an adjustable pneumatic (vacuum-operated) web braking device  19 . If the length of the loop  11  drops below a preselected threshold value, the sensor  12  transmits a signal which causes a suitable motor or transmission (not shown) to pivot a lever  14  carrying initiator  16  which causes the advancing unit  2  to supply the web  1  at a higher rate in order to increase the length of the loop  11 . 
     The second advancing unit  17  exerts upon the web  1  a pull which causes successive increments of the web to leave the chamber  8  of the receptacle/reservoir  6  by advancing over a deflecting roll  18  and thereupon along an arcuate portion for the path, namely about approximately one-half of the peripheral surface of a roller  21  forming part of the braking device  19  located in a fourth portion of the path downstream of the third portion (magazine  4 ) and upstream of a fifth portion defined by a curling device  38 . 
     As can be seen in FIGS. 2,  3  and  4 , the roller  21  of the braking device  19  comprises two axially spaced-apart flanges  22 ,  23  which confine successive increments of the running web  1  to travel about approximately or exactly one-half of the cylindrical peripheral surface of a median portion  27  of the roller. The median portion  27  is provided with an array  24  of annuli of radially inwardly extending suction ports  26 . These ports form rows which are parallel to the axis of the roller  21 , and each such row communicates with one of an annular array of axially parallel channels  28  (FIGS.  3  and  4 ). The median portion  27  of the roller  21  surrounds a shaft  25  which serves as a means for rotating the roller  21  in the direction of arrow  33  (FIG.  1 ), i.e., counter to the direction (arrows  3 ) of advancement of the web  1  along its path from the source, through the nip of the rollers forming part of the first advancing unit  2 , through the magazine  4 , around the deflecting roll  18 , through the braking station accommodating the median portion  27  of the roller  21  of the device  19 , around the curling device  38 , and through the nips of the rollers forming part of the second advancing unit  17 . 
     Those ports  26  which are overlapped by the arcuate portion of the web  1  then advancing through the braking station are connected to a suction generating device  34  (such as an ejector type pump) by a conduit  31  and an arcuate chamber in the stationary friction ring  29  for the shaft  25  of the roller  21 . The intensity of subatmospheric pressure in the conduit  31  can be regulated in several ways including by a braking force adjusting means  36  shown in FIG.  1  and being operatively connected to the suction pump  34 . The braking action of the median portion  27  of the roller  21  upon the running web  1  can be regulated by varying the subatmospheric pressure in the conduit  31  and/or by varying the rotational speed of the shaft  25 . The speed of this shaft can be close to zero and (as already pointed out hereinbefore) the shaft  25  rotates the roller  21  in the direction indicated by the arrow  33 , i.e., counter to the direction of lengthwise movement of the web  1  (arrows  3 ) under the action of the advancing units  2  and  17 . 
     Since the peripheral surface of the median portion  27  of the braking roller  21  is likely to force certain impurities (such as web fragments obtained at the perforating station ahead of the first advancing unit  2  and/or tobacco dust) into the ports  26 , the device  19  preferably includes or cooperates with a port cleaning or impurities expelling device. The improved cleaning device includes a conduit  32  (FIG. 4) connected to the output of a source of compressed gaseous fluid (e.g., an air compressor, not shown) and to those ports  26  which are not overlapped by the web  1  (i.e., the ports  26  which happen to be located in the momentarily upper half of the roller  21  shown in FIG.  1 ). In other words, approximately one-half of the ports and the associated channels  28  receive (at any instant) compressed air via conduit  32  (and a suitable cavity in the friction ring  29 ) to undergo a cleaning treatment, and the other ports  26  are then connected to the suction generating device  34  by way of the conduit  31  to attract the running web  1  to the adjacent half of peripheral surface of the median portion  27  of the roller  21 . 
     The selected low peripheral speed of the median portion  27  (in the direction indicated by the arrow  33 ) enables the source of compressed air to adequately clean successive groups of ports  26  before such ports are again overlapped by the web  1 . 
     The aforementioned device  36  is preferably adjusted or set up in such a way that the braking force exerted by the ports  26  which are momentarily overlapped by the running web  1  is normally maintained at a fixed value or within a preselected optimum range. The device  36  is or can constitute a commercially available pressure regulator. For example, the suction generating device  34  can constitute a PAIB vacuum pump of the type known as M (model “Chip”). 
     The extent or magnitude of tension in the web portion between the braking device  19  and the second web advancing unit  17  is monitored by a sensor  37  which can constitute a radial force measuring arrangement of the type known as M1191 distributed by the Firm Tensometric Messtechnik GmbH, Wuppertal, Federal Republic Germany. The sensor  37  is designed to transmit analog output signals which are utilized to regulate suction in those ports  26  of the median portion  27  of the roller  21  which are connected to the conduit  31 . Such regulation compensates for those fluctuations of quality of the oncoming increments of the web  1  which are capable of influencing tension in those successive portions of the web that advance along the curling device  37 . 
     The device  37  serves to “break” or bend the web  1  with a constant force, namely to subject the web to such treatment in the respective (fifth) portion of the path between the braking device  19  and the advancing unit  17 . It has been ascertained that a web which is caused to be acted upon by a curling device while being subjected to a predetermined constant tensional stress can be subdivided into uniting bands (one shown at  43  in FIG. 5) which can be converted into superior tubular envelopes connecting plain cigarettes with filter mouthpieces, at least as far as the establishment of a desired permeability (flow of atmospheric air into the column of tobacco smoke) in the convoluted uniting bands is concerned. 
     FIG. 5 shows a finished filter cigarette  39  with all of its tubular (normally cylindrical) constituents drawn to a larger scale for the sake of clarity. Such tubular components include a cylindrical envelope  41  made of cigarette paper and surrounding a rod-shaped filler of comminuted tobacco leaves and/or reconstituted tobacco and/or artificial tobacco. The envelope  41  may but need not be porous but the tubular envelope  42  of the cylindrical filter mouthpiece  40  is made of a foraminous wrapping material. The envelope  42  and the adjacent end portion of the envelope  41  are connected to each other by a foraminous third tubular envelope  43  constituting a length of properly treated (perforated, looped, tensioned, stretched and curled) web  1 . Certain perforations of the convoluted uniting band  43  are shown at  47  and are radially outwardly adjacent a non-adhesive annular portion  46  of the internal surface of the envelope  43 . A layer or film  44  of a suitable adhesive (such as a hotmelt) coats the inner side of the envelope  43  at both sides of the non-adhesive annular portion  46 . 
     If the envelope  43  is made of a convoluted uniting band constituting a section of an improperly tensioned (and hence unpredictably curled) web  1 , the permeability of the composite tubular envelope including the envelope  42 , the two-piece film consisting of adhesive  44 , and the envelope  43  (with perforations  47  in register with the uncoated median portion of the underside of the envelope  43 ) will depart from optimal permeability. Improper tensioning of the web  1  can be eliminated by adjusting the braking device  19  accordingly so that the tension of successive increments of the web arriving at and being deflected by the curling device  38  is within a desired (optimum) range. 
     If the curling action upon successive increments of the web  1  is carried out while the tensioning of the web fluctuates, the uncoated median portion of the envelope  43  is likely to sag inwardly (as shown at  45  in FIG. 5) when the tensioning is excessive, and this alters the rate of air flow into the filter mouthpiece  40  by way of the perforations  47 , the median portion of the uncoated (at  46 ) inner side of the envelope  43  (i.e., between the two annuli of the composite adhesive layer  44 ), and throug the foraminous envelope  42 . The likelihood of the development of defects (at  45 ) is much more remote if the web  1  is subjected to the aforedescribed treatment first in the magazine  4  and thereupon in the path portion between the deflecting roll  18  and the curling station, at  38 . The monitoring (at  37 ) and regulation (at  36 ) of tension (established at  19  are of particular importance for the establishment and maintenance of an acceptable curling action. 
     The improved apparatus can be further provided with means for monitoring the web  1  for the presence of splices (not specifically shown) which are normally utilized to connect successive lengths or strips to each other end to end to thus form a continuous web  1 . The means for monitoring the web  1  for the presence of splices, is shown at  48 . Signals from the monitoring means  48  are utilized to adjust, such as deactivate, the curling device  38  when a splice arrives at the curling station. The exact manner in which this can be accomplished (e.g., by resorting to a rotary or back-and-forth rockable curling device and/or to a member which lifts the spliced portion of the web off the curling device) is or can be the same as disclosed in the aforementioned &#39;842 patent to Ehlich et al. The curling device  38  can be deactivated in its entirety (or its effect upon the condition of the web  1  can be reduced) whenever a splice reaches and advances past the curling station. For example, the sections or lengths of the web  1  between successive splices can be subjected to a first (e.g., more intensive) curling action, and the splice-containing portions of the web can be subjected to a second (e.g., less intensive) curling action. This reduces the likelihood of breakage (tearing) of the web at a splice. 
     FIG. 1 further shows a sensor  49  which monitors the web  1  downstream of the curling device  38  for the presence of breaks and/or cracks in the web portions advancing toward and beyond the second advancing unit  17 , e.g., to an adhesive-applying station (see the composite adhesive layer  44  in FIG. 5) and thence through a cutter which repeatedly severs the leader of the web to thus produce a series of discrete uniting bands ready to be converted into envelopes  43  which are thereupon convoluted around pairs of rod-shaped articles ( 40 + 41 ) in a filter tipping machine serving to turn out filter cigarettes  39 . 
     An advantage of roller cleaning means including the conduit  32  is that the suction upon that portion of the running web  1  which actually contacts the median portion  27  of the roller  21  (between the flanges  22  and  23 ) is less likely to depart from the selected range than in the absence of expulsion of impurities (if any) from those ports  26  which are about to be again overlapped by the web. 
     It is clear that other types of cleaning devices (e.g., devices which suck, rather than blow, impurities from the ports  26  momentarily not overlapped by the running web) can be utilized with equal or similar advantage. Furthermore, one can utilize a cleaning device which is set up to operate intermittently (i.e., at pre-selected intervals) rather than continuously. 
     The tension sensor  37  can influence the condition or operation of the preferably adjustable (such as activatable and deactivatable) curling device  38  and/or the extent to which the web is attracted to the lower half of the median portion  27  of the roller  21  shown in FIG.  1 . It is presently preferred to design and set up the improved apparatus in such a way that a portion ( 45 ) of the envelope  43  does not appreciably sag (or does not sag at all) into the annular clearance between the two annuli of adhesive  44  shown in FIG.  5 . 
     The illustrated magazine  4  can be replaced with other types of magazines which are capable of exerting a desirable (tranquilizing) influence upon successive increments of the web advancing toward the braking station. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of the above outlined contribution to the art of treating running webs of wrapping material for smokers&#39; products and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the appended claims.