US 2940891 A
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June 14, 1960 P. A. MULLER 2,940,891 Memos OF PRODUCING ENDLESS FIBRE WEBS HAVING IRREGULAR SURFACES F'il ed Aug. 23. 1956 I 2 Sheets-Sheet 1 26 20 munuus v HEAT SUPPLY ROLLS HIGH FREQUENCY TO FILTER PLUG r I ORMAgl'gaFETTE F193 Fig.5 Fig.7 Fig.9 I4 1M 4"14 I 4 6 Fig.8 W o o i in :2
P. A. MULLER 2,940,891 METHOD OF PRODUCING ENDLESS FIBRE WEBS HAVING IRREGULAR SURFACES Jame 14, 1960 2 Sheets-Sheet 2 Filed Aug. 23. 1956 Fig. 17
United States Patent ()fifice Patented June .14, 1960 METHGD F PRODUCING ENDLESS FIBRE WEBS HAVING IRREGULAR SURFACES Paul Adolf Muller, Rosenhugel, Herrliherg, Switzerland Filed Aug. 23, 1956, Ser. No. 605,893
5 Claims. (Cl. 162-113) The present invention relates to a method of producing endless fibrous Webs which have their surfaces provided with irregularities, in particular crimped paper Webs for smoke filters.
Crimped papers are already known and largely used for the manufacture of filter bodies for cigars and cigarettes. Since fiat paper webs require to be formed into cylindrical plugs to constitute such filter bodies, the paper webs employed should display only a small degree of rigidity at least in one direction. A non-crimped paper web would, when compressed into a cylindrical cord, display uneven folds and irregular buckling which results in irregular cord cross section having hollow spaced and disconnected channels, which would constilute a structure entirely unsuitable for filtering purposes. Crimped paper, however, does not display the said disadvantages, and paper filter plugs are therefore manufactured almost exclusively from such material. Crimping of the paper webs also facilitates the manufacture of such filter plugs by means of machines and further ensures the necessary porosity.
The manufacture of crimped paper has so far been effected almost exclusively by a generally known process in which an endless moist paper web is fed to a heated cylinder for drying and then removed from the cylinder by a blunt scraper so that the fiat paper web is upset in the longitudinal direction and provided with transverse folds. This operation causes the material to be condensed, and the crimped paper web always possesses a greater weight per unit length than the original flat web, the increase in weight being proportional to the so-called crimping rate. If the fiat paper web is transformed into crimped paper with a crimping ratio of 3:1, a unit length of the final product may be extended to three times its length and flattened into a smooth web, and accordingly, when cri'nped, it possesses three times the weight of the fiat web.
in a paper web manufactured according to this method, s crimping folds and grooves run transversely to the 'irection of travel. While the crimping of the paper web indispensable, its direction transverse to the longiudinal axis of the web renders the machines required ror the manufacture of filters and the process involved complicated. As the filter cord is produced by gathering one or several paper strips of a predetermined width, which can be done in a direction normal to the crimping grooves only, strips of the desired width must be cut from the wide crirnped paper Webs, so that the said strips cannot be longer than the width of the said paper web. These strips are then supplied to the gathering device of the filter plug machine in the longitudinal direction, i.e. parallel with the crimping grooves.
In order to enable these products to be manufactured in continuous operation, such longitudinally crirnped paper strips of limited length are placed end to end and continuously fed into the gathering device. Apart from the intermittently operating cutting and conveying device thereby required, which involves greater danger of breakdowns, the short stn'p lengths involve a number of highly undesirable weaknesses. In order to ensure accurate feeding of the consecutive strips into the gathering device, strips must not be wider than 4 or 5 centimetres, which makes it necessary, in view of material requirements due to the dimensions and the density of the filter cord, to stack four to six crimped strips for joint handling in the gathering device which in turn renders the feed mechanism still more complicated. Another possibility of continuous manufacture having been unknown so far, large mechanical equipment has been designed and put into practical operation. It has also been suggested to join the individual strips together by manual gluing in order to ensure continuous operation as disclosed in German Patent No, 626,257.
A further disadvantage besides this difiiculty in feeding is that both the first and the last filter of each crimped strip of predetermined length must be considered as waste because either of them may contain the joint between two successive strips. This must be avoided with strips not joined together by gluing since part of the filter plug might easily fall out of the cigarette, while the glued seam would affect the filtering action in strips which are glued.
It has been attempted to feed uncrimped and particularly resilient paper, such as cellulose wool, directly into the gathering device of a filter plug machine. The filters thereby formed of uncrimped fiber webs, however, display an undesirably high resistance to suction when filled with sufiicient density. If the filling is made less dense in order to reduce resistance to suction to an admissible level, the filter plug tends to shrink in use owing to the absorption of moisture so that it may drop out of the cigarette.
Comprehensive experience in this field has led to the discovery that a certain longitudinal structure of the paper or fibrous webs to be formed into filter plugs is essential to produce satisfactory resistance to suction, homogeneous distribution of the material and sufficient strength.
The difficulties described above have led to the development of the method of manufacturing longitudinally crimped endless material webs (compare my copending patent applications No. 502,016 and No. 502,017), in which a flat paper web is the base material which is drawn from a delivery roll and suitably treated.
The present invention solves the same problem in another manner and relates to a method of producing endless fibrous webs with surface irregularities from the fiber pulp usual in the manufacture of paper, which is poured on a traveling web of wire and dried in further operations. The method is characterized in that, at least in one stage of its production path, the web, while still plastic, is caused to traverse a plate of which the contact surface is provided with irregularities which are at least partly reproduced on the fibrous web. This ensures that the irregularities thereby produced will at least partly be preserved in all manufacturing stages undergone by the fibre web after deformation.
The endless web produced acording to this method is characterized by a longitudinal structure and irregularities at least on one surface of the web. A number of embodiments of the invention will be described in greater detail in conjunction with the drawings, in which:
Fig. 1 is a diagrammatic view of an embodiment of a device designed to perform the method according to this invention;
Figs. 2a, 2b are a side view, tively, of a wire-mesh web;
Figs. 3, 4 and 5, 6 and 7, 8 and 9, 10, respectively, are enlarged cross sections and plan views of Webs of difierent configuration;
and a plan view respecforms a. moist layer.
' to be formed while the top cloth 11 returns this pair or rolls and is given a plurality grooves parallel with the direct-ion of travel. According to Figs. 11, 12' are enlarged cross sections of a longitudinally cnm' ped web;
, Fig. 13 is a perspective view of a web;
Figs. 17, 18, 19, 20 are cross sections normal to thev The conventional equipment for the manufacture of paper comprises, as Fig. 1 shows diagrammatically, a wire screen or perforated support 1 which is pervious to water, such as a wire cloth, travelling along rolls 2, 3, 4,
5 in an endless loop. Fibre pulp 7 is poured on the upper face-of the travelling wire cloth 1 from container 6, and the excess'liquid. drains through the wire cloth 1 or is removed by suction devices 8, 9 so that the fibre pulp This layer is taken up by the top cloth 11 in the trough formed between cylinder 4 and roll 10; it adheres to the cloth 11 and'is carried'along to the first drying drum 12 The incipient drying action of the firstrdrying drum 12 causes the fibre layer to be taken off the top cloth 11 and a loose and plastic fibre web 14 I to the trough via the guide pulley '13-.
- Depending on dwell, drum temperature and thickness of the fibrelayer, one or more drying drums 12 should be provided in orderto give the fiber web 14-sufiicient strength. and plasticity for the subsequent treatment designed to impart to said web desirable surface irregularities.- -In the embodiment shown in Fig. 1 the fibre web 14 travels between two rolls 15,-16 and is perforated from one or two sides so that it assumes the structure shown in Figs. 3, 4. The plastic'fiber web 14 is then supplied to a pair of corrugation rolls 17, 18 which are provided with ribs and grooves arranged around their circumfen' ence, the ribs of roll 17 engaging the grooves of roll 18 and vice versa. 'The'plastic fibre web undergoes still further permanent deformation during its passage through of longitudinal the axial distance of the ribs and their dimensions, a perforatedand longitudinally grooved fibre web according to Figs. 5, 6 or Figs. 7, 8 is produced. In order to make the uniform longitudinal prepared, which is still plastic, passes through a further pair of rolls 19, 20 of which the cylindrical surfaces are designed similarly to a helical gear or provided with a knurled surface. After passing rolls 19, 20 the fibre web 14 displays the configuration approximately shown in The fibreweb' 14, which is equippedwith irregularities,
grooves, perforations etc. must then be dried, which should, if possible, be elfected without contact with a support, e.g. in a high-frequency field set up by a generator between electrodes 22, '23. A drying plate may be employed if it is ensured that the fibre web' rests on it slightly, by way of example by being guided against it from above and from the sides by means of a hot air current. After drying, the fibre Web prepared in this manner is then comparatively'jstable and invariable and can accordingly be reeled up, possibly after previous subdivision into individual bands, or be supplied direct to a filter plug or cigarette machine for further treatment.
In the embodiment described in conjunction with Fig. 1, all operable means designed to produce surface irregularities in the web are arranged subsequent to the drying drum 12. Obviously the method is not limited thereto since the fibre web may, wherever suitable, be passed across a support of which the corresponding condiagram of an embodiment of a,
, grooves more irregular. and more similar to random folds, the fibre Web thus be'produced in which the upper and Figs. 1.4, 15, ,16 are plan viewsrof further embodiments as with a plurality of spikes 24 tact surface is equipped with irregularities which are then at least partially reproduced in the fibre web. Care must be taken to ensure that the further manufacturing stages passed by the fibre web do no't'entirely disturb or remove the irregularities thereby produced.
By way of example the wire cloth 1 as illustrated in Figs. 2a, 2b maybe equippedwith' surface irregularities, such evenly distributed over the supporting surface which 'form perforations layer cast'on. These spikes 2.4 should project from the wire cloth 1 no fartherthan possible without damaging the top cloth 11. These spikes 24 may be replaced by knots or other surface irrcgul'alities which do not interfere layer produced on the support effect an irregular, e.g.
material on the wire support so that the fibre web 14 ap- V usually passes several further display different surface structures.
pearing after the drying drum 12 is provided with denser and less dense longitudinal strips or band sections.
011 the processing path between the trough and the first drying drum 12, in which the still loose'fibi'e web rolls, a desired structure on one or both surfaces of the web may be produced by a suitable design of the supporting surfaces of the said rolls or by any other appropriate means. In that case, drying may be effected either by means of conventional drying drums 12. if partial destruction of the surface structure obtained is admissible, or by means of high-frequency or infra-red irradiation without contact, or light application of one side on drying plates.
. In certain applications of the fibre web described, sub:
division into longitudinalbands or strips having different surface structures or thicknesses is important.
This rnerely requires that at least one of the pairs of rolls which determines the structure of the fibre web during manufacture be equipped with annular areas axially separated fi'om one another which are provided with different irregularities. By-way' of example, the device shown in Fig. 1 may be provided with knurling rolls 19, 20 which cause ;a division of the fibre web into six parallel longitudinal strips of which adjacent ones always A material web 14 perforated by the rolls 15, 16 is crimped by rolls 17, 18 across its entire width and then has the regular crirnps broken by 'knurling in separate parallel longitudinal strips by means of rolls 19, 20. The fibre web 14 is then subdivided with longitudinal strips of which some have continuous crimps while the others are provided with a knurled structure.
Such division of the pairs ofrolls into separate axial annular areas having difierent surface structures may naturally be provided on all other pairs or rolls of the device or plant according to Fig. 1, commensurate with the type of structural properties of the fibre web desired. By way of example, the pair of crimping rolls, 17, 18
. may be designed so that adjacent longitudinal strips of the fibre. web are stretched to various degrees trans- 'versely to the direction of travel during crimping, and
this may be effected by different grooves in t-herolls. A loose fibre web may also be compressed in its structure inadjacent longitudinal bands either by compression normal to the surface of the fibre web, or transverse thereto, one longitudinal band being stretched and the other being condensed approximately to the same degree so that the total width of the fibre web may, if desired,
7 always be maintained without any change or alteration. Moreover, individual longitudinal strips may be perforated or embossed while the immediately adjacent strips of the band are given other perforations or are embossed or left plain. Finally individual longitudinal strips may have at least one surface roughened.
The different structure of adjacent longitudinal strips may be produced, as stated above, on a uniformly crimped fibre web, as by perforation of individual longitudinal bands and/or condensation of the unperforated longitudinal bands. Also perforation and subsequent uniform crimping of the entire web with later perforation of individual longitudinal strips only will produce different structures in adjacent longitudinal strips.
With structures having iregularities, such as embossed protuberances, perforated configurations, etc. periodically repeated along the length of the web it is important for a fibre Web for use in the manufacture of smoke filters that the spaces betwcn such successive irregularities be kept small relative to a web length of mm. This will ensure that when an endless filter cord is manufactured from the fibre web and then subdivided into individual filter plugs which in comparison to each other cannot possess marked differences in structure.
It is the purpose of the said band-type differentiation to provide an endless fibre web which is composed of adjacent longitudinal strip sections or sectional bands having greater and lesser mechanical strengh in the direction transverse to the direction of feed or travel. It is also desirable that said longitudinal sectional bands having greater mechanical strength also display lesser swelling and absorptive properties. These two properties render such fibre webs particularly suitable for the manufacture of filter plugs since the mechanically stronger longitudinal bands ensure stability of the filter body even when the mechanically weaker longitudinal bands are subjected to greater swelling during use owing to the absorption of the undesirable smoke components which are to be filtered off.
The annular areas of the rolls producing the structural differences in the individual longitudinal bands have their surfaces provided with a variety of irregularities. By way of example, individual annular areas may be designed as spiked rollers, or a pair of associated rollers may form embossing die and punch means, respectively. Also grooves arranged along the circumference, surface areas with helical teeth or with brush-type roughening members may be provided. In the individual pair of rolls one is advantageously provided with a lining formed of resilient rubber-type material. Figs. 13 to 20 inclusive show various samples of fibre webs which may be produced with longitudinal sectional bands according to the method disclosed. Fig. 13 shows a fibre web having only one longitudinally crimped band section 26 at its centre. The longitudinal band section 27 has been stretched in the direction transverse to the direction of travel indicated by arrow 29 to such an extent that a plurality of irregularly disposed cracks have been produced without rupturing the fibre Web as a whole. The longitudinal strip section 23 is equipped with a plurality of perforations defined by frayed edges, the direction of the perforated edges being partly downward, partly upward. The spaces at which the perforations are arranged in the direction of arrow 29 are small relative to a web length of 10 mm. Apart from coarse perforations, fine perforations in longitudinal sectional bands 26, 28 have been efiFected prior to longitudinal crimping of strip section 26.
Figs. 14, illustrate the appearance of fibre Webs where the entire web has first been longitudinally crimped and some longitudinal sectional bands have subsequently been subjected to treatment by a knurled roll (Fig. 14), and vertically condensed and perforated or embossed, respectively (Fig. 15). Fig. 16 shows a fibre web which has longitudinally corrugated and differently embossed non-corrugated longitudinal band sections.
A longitudinally crimped fibre web with unequal groove dimensions in adjacent longitudinal bands is shown in Fig. 17, the material being more strongly stretched in the transverse direction in the larger grooves, which reduces their mechanical strength while increasing the absorptive power of the material. Diiferently condensed structures are shown in Figs. 18, 19. In the material web according to Fig. 18, condensation has been efi'ected transverse to the direction of travel, individual longitudinal strips being stretched and adjacent strips being condensed, and at the same time equipped with several longitudinal grooves. Condensation normal to the web plane is shown in Fig. 19, the condensed longitudinal bands and the adjacent non-condensed bands being also perforated. Naturally condensation and embossing of the loose fibre web as illustrated in Fig. 20 may be effected simultaneously either on both sides or on one side only.
It will be noted that in all these embodiments the width of the sectional bands, as seen in Figs. l7 to 20, remains always the same despite different irregularities applied to said bands.
A further embodiment of the mechanical equipment for the manufacture of fibre webs according to the present method is shown in Fig. 21. A lower wire cloth 30 and an upper wire cloth 31 are provided of which the portions facing each other form a narrow gap 32 and travel in the same direction. From container 33 the fibre pulp is poured into the gap 32 so that the said pulp is compressed between the wire cloths 3t), 31. A pair of rolls 34, 35 may increase the pressure which is of advantage, by way of example, where the surface structure of the wire cloths 39, 31 is to be reproduced in the fibre web. Dehydration of the fibre layer may be accelerated by compressed air nozzles 36 and suction nozzles 37.
The upper Wire cloth 31 travelling about rolls 38, 39 is shorter than the lower wire cloth 30, so that the fibre layer resting on the latter may be passed beneath a drying device 49, the fibre web being dried by high-frequency or heat radiation. The fibre web thereby deformed may be taken from the lower wire cloth 30 at its rear end in any known manner and be subjected to further treatment.
Various changes and modifications may be made without departing from the spirit and scope of the present invention and it is intended that such obvious changes and modifications be embraced by the annexed claims.
Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:
l. The process of manufacturing a Web from pulpy fibrous substance comprising the steps of pouring fibrous pulp onto perforated support means to form thereon a moist layer of fibrous substance, subsequently removing sufiicient moisture from said substance layer to form a fiber web still in plastic state, deform-ing said web to thereby achieve at least two adjacent longitudinal strips different in patterns from each other and adhering to each other, subjecting one of said strips to perforating action thereby to obtain openings therein defined by frayed edges with the fibers of the latter loosely connected to and at least partially offset with respect to the surface of said web, crimping the other of said strips to constitute grooves therein thereby to obtain sufficient strength for said web, and then leading said Web past drying means, to transform said web from its plastic state into a substantially dry state, whereby the fibers of said web will remain loosely connected to said frayed edges.
2. The process of manufacturing a web from pulpy fibrous substance comprising the steps of pouring fibrous pulp onto perforated support means to form thereon an elongated moist layer of fibrous substance, subsequently removing sufiicient moisture from said substance layer to form a fiber web still in plastic state, deforming said web to thereby achieve at least two adjacent longitudinal strips different in patterns from each other and adhering to each other, subjecting one of said strips to perforating action thereby to obtain openings therein pulp substance 1? defined by frayed edges with the fibers of the latter loosely connected to and at least partially offset with respect to the surface. of'said web, crimping the other of said strips to constitute gtooves; ,therein running longitudinally of said other strip, ,therebyto obtain sufficient strength for said;web,:and 'thentleading said web past drying means to transform said webfrorn its plastic state into a substantially dry state, whereby the fibers of said web will remain loosely connected to said frayed edges. 7
. 3.,The process of manufacturing aweb from pulpy fibrous substance comprising'the steps of pouring fibrous pulp onto perforated support means to form thereon a moist layer of'fibrous substance, subsequently removing sufficientmoisture from said substance layer to form a fiber web in form able state, deforming said web to thereby achieve a plurality of adjacent longitudinal strips of which two are different in patterns from each other and'all of which adhere to each other, subjecting said strips'to'perforating action thereby to obtain passageways therethrough defined by frayed edges with the fibers of strengthv in transverse the latter extending therebeyond and at least partially offset with respectto the surface of said Web, crimping at leastone strip between adjacent strips, thereby providing grooves therein running in lengthwise direction of said strips to obtain suflicient strength for said web, and then leading said web thus prepared past drying means, to transform said web from its formable state into a substantially state, While the fibers of said web remain loosely connected to said 'frayed edges.
' 4. The process of manufacturing a web from pulpy fibrous substance comprising the steps of pouring fibrous thereon an elongated moist layer of fibrous substance, subsequently drying said substance layer sufiicient to form a fiber web in formable state, subjecting said web to deformation and perforating actions to thereby achieve adjacent longitudinal strips different in patterns from each other and adhering to each other and to obtain passageways. throughsaid strips defined by frayed edges with the fibers of the latter connected to and extending beyond said passageways and at least partially offset with respect to the surface of said web, said deformation action including. the step of providing grooves running longionto perforated support means to form tudinally of some of said stfipsthereby to obtain sufficient direction for said web, and then leading said web past drying means to transform said w vfrom flfo tm 7 t te in a s bs an y d state. a 1 I a 5. The process of manufacturing a web from pulpy fibrous substance comprising the, steps of pouringsaid fibrous pulp substance onto perforated support means to form thereon an elongated moist fibrous layer, subsequentlyremoving moisture from said layer to form a fibrous web in formable state, deforming and perforating said web to thereby achieve longitudinal strips of alternating different patterns, one of said patterns presenting a strip with openings therethrough, which openings are defined'by frayed edges with fibers-of the latterext'ending beyond and at least partially offset with respect to the surface of'said web, another of said patterns presentinga stripwith grooves running longitudinally of said latter strip, thereby to obtain suflicient strength in transverse and longitudinal directions of said web, and then subjecting said web to drying action for obtaining a web in a substantially dry state.
References Cited in the file of this patent UNITED STATES PATENTS 1,224,650 Kitchen May 1, 1917 1,582,838 Lorenz' Apr. 27, 1926 1,765,520 Adams June 24, 1930 1,946,838 Cofrin Feb. 13, 1934 1 2,043,351 Fourness June 9, 1936 2,113,431 Milliken Apr. 5, 1938 2,130,375 Atkins Sept. 20, 1938 2,164,702 Davidson July 4, 1939 2,245,014 Sherman June 10, 1941 2,281,945 Milliken May 5, 1942 2,405,249 Wilson Aug. 6, 1946 2,680,996 Brown June 15, 1954 i FOREIGN PATENTS Y J 380,041 Great Britain Sept. 6, 1932 482,145 Great Britain Mar. 24, 1938
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