US3035497A - Method and apparatus for making filter rods - Google Patents

Description

May 22, 1962 R. o. WHITEHEAD ET AL 3,

METHOD AND APPARATUS FOR MAKING FILTER RODS Filed Dec. 19, 1958 may/#20 MA47066 RAYMOND 0. W/l/TE/S'EAD JOSE/q! MAST/FR INVENTORS United States Patent 3,035,497 METHOD AND APPARATUS FOR MAKING FILTER RODS Raymond 0. Whitehead, New Brunswick, Joseph Master,

Highland Park, and Richard Marogg, New Brunswick,

N.J., assignors to Kimberly-Clark Corporation, Neenah,

Wis., a corporation of Delaware Filed Dec. 19, 1958, Ser. No. 781,622 4 Claims. (Cl. 93-1) This invention relates to the manufacture of filters of the type especially adapted for use in so-called filter tip cigarettes, and has particular reference to a method and apparatus for making a filter rod consisting essentially of a compacted rod-like mass of fibrous filtering material.

It is a general object of the invention to provide certain improvements in the apparatus and procedural steps described and illustrated in US. Patent No. 2,849,932, issued September 2, 19-58.

The invention relates to the known type of procedure in which a Web of fibrous material such as paper or its equivalent is drawn from a continuous supply, then converged or gathered to form' a relatively compact rod-like strand or bundle adapted to be enclosed within a wrapper strip. The resultant continuous filter rod may be cut into selected lengths, and individual short lengths are ultimately incorporated with the cigarette by the cigarette manufacturer, or used in similar fashion in cigarette holders or the like.

In accordance with the procedure described in said earlier patent, No. 2,849,932, the web of fibrous material is subjected to mutilation prior to its formation into the rod-like condition. The mutilation is of a kind which lacerates the web without destroying the continuity of the web, thereby separating and exposing additional fibers of the web. It is an object of the present invention to pro vide improvements in this procedure, and in an apparatus for carrying it out, whereby enhanced fiber separation and exposure can be achieved, and with greater uniformity, economy, and reliability when the invention is practiced on a commercial scale.

More specifically, the improvements in the apparatus involve a more efiicient means for lacerating or mutilating the continuous web of fibrous material as it is drawn from a supply; and another improvement relates to a new and unusually eifecive device for initiating the convergence of the mutililated Web toward the compacted rod-like formation. The improvements in the basic procedure reside in the preliminary formation of transverse crinkles or crepes in the web of fibrous material and the subsequent subjection of the web to longitudinally extending corrugations in combination with irregular tears along closely spaced longitudinal lines. The combined effect of transverse deformations in the web at the start, and longitudinal distortions and lacerations superimposed thereon, has proven to be unusually desirable in achieving the purposes of the invention.

The preferred mode of attaining these objectives, and such other obejcts as may hereinafter appear or be pointed out, is exemplified in the accompanying drawings in which- FIG. 1 is a diagrammatic perspective view of the procedure and apparatus in the region to which the present invention relates;

FIG. 2 is an elevational view of one of the mutilating or embossing rollers shown in FIG. 1;

FIG. 3 is a greatly enlarged fragmentary view of the nested mutilating rollers, with the web of material passing between them;

FIG. 4 is a fragmentary face view of the fibrous web prior to its subjection to the action of the mutiliating rollers;

FIG. 5 is a greatly enlarged schematic cross-sectional view in the direction 5-5 of FIG. 4;

FIG. 6 is a fragmentary face view of the fibrous web after passing between the mutilating rollers;

FIG. 7 is a greatly enlarged schematic cross-sectional view in the direction '7-7 of FIG. 6; and

FIG. 8 is a perspective view of a piece of the resultant filter rod.

The filtering material is preferably, but not necessarily, composed of relatively thin cellulosic tissue of fibrous nature having good filtering characteristics. It is easily tearable in a manner to spread or separate its fibers, and it has a softness which permits it to be readily compressed or compacted into rod-like formation without destruction of its porosity. While the terms web and paper are both used herein, the intent in each case is to refer to any fibrous material in sheet form having the tearability, porosity, and other characteristics alluded to.

The procedure involves the advancement of a web 10 of this material from an appropriate supply to and between a pair of mutilatiug or embossing rollers 11 which are mounted for rotation on parallel adjacent axes. The mutilated web (indicated by the reference numeral 12.) is caused to pass around a special guide roller 13 which directs the web through a sharp change of direction and initiates the convergence of the web, as indicated at 14, toward a compacted rod-like formation. The compressed and compacted web is appropriately tensioned (by a means not shown in FIG. 1) and is enclosed within a. wrapper 15 preferably composed of paper (see FIG. 8). A continuous length of this filter rod emanates from the output end of the apparatus, and is cut off into desired lengths by a suitable knife or other cutting instrumentality. Subsequently the filter rod is cut into relatively shorter lengths for incorporation into cigarettes or cigarette holders.

The apparatus for carrying out this procedure is preferably of the general character shown in the aforementioned Patent No. 2,849,932, and includes a means for delicately adjusting the mutiliating rollers 11 toward and away from each other, so that the spacing between them may be varied to a fine degree.

One of the features of the present invention resides in the novel configuration and co-action of the rollers 11. As best indicated in FIGS. 2 and 3, these rollers have each the same circumferentially grooved configuration defining closely spaced alternate ridges and valleys. The invention is not restricted to any specific set of dimensions, but in order that the nature and functioning of the apparatus may be better understood, it may be stated that valleys spaced apart by 0.05 inch (center to center), having a depth of 0.04 inch and a width of the order of 0.035 inch, have proven to be satisfactory for the purpose. Each of the rollers may have a diameter of approximately 3 inches, and a length dependent upon the width of the web under treatment. A length of approximately 20 inches is usually sufiicient.

A special feature of the new surface configuration resides in providing each ridge with a cross-sectional contour which exposes at least one sharp edge, and imparting to each valley a cross-sectional contour which presents a relatively fiat surface in opposition to each ridge edge when the rollers are arranged in nested proximity with the ridges of each roller extending into the valleys of the other. The preferred way of achieving this objective is shown in FIGS. 2 and 3, in which it will be noted that each of the ridges 16 has a fiat outer face 17, bounded by sharp lateral edges 18. Each of the valleys 19 has a smoothly curved concave cross-sectional contour. It will be apparent from a consideration of FIG. 3 that each valley thus presents a relatively fiat surface in opposition to each ridge edge 18 of the other roller.

Because of the arrangement of the rollers 11 in nested proximity, the web 18 that is caused to pass between them is stretched and distorted into a longitudinally corrugated state. It is squeezed to a maximum degree along the parallel longitudinal regions which pass over the sharp corners or edges 18. By adjusting the proximity of the rollers, the degree of this squeezing action can be regulated so that it will produce an irregular and haphazard tearing or laceration of the web without impairing the transverse continuity of the web. These lacerations are diagrammatically represented in FIGS. 1, 6 and 7 by the reference numerals 20. The minute corrugations are roughly indicated at 21 in FIG. 7.

A further feature of the invention, contributing in large measure to the achievement of an enhanced fiber separation and exposure, with consequent improved filtering qualities, lies in the creation of transverse crimps or crinkles in the web it prior to its subjection to the corrugating and mutilating action of the rollers 11. These transverse crepes are'intended to be represented in a diagrammatic fashion at 22 in FIGS. 4 and 5. This creping'may be achieved in any well-known fashion, not necessarily by apparatus forming part of the present improved device. It has been found that paper which has been transversely creped lends itself unusually well to the stretching, grooving and lacerating action of the rollers 11; and that the combined effect of transverse crinkles at the start, and longitudinal corrugations and lacerations superimposed thereon, produces a desirable fiber separation and exposure of unusual effectiveness from a filtering standpoint. Moreover, the inherent longitudinal stretchability of transversely-creped paper makes the action of the mutilating rollers more controllable, so that desirably uniform results can be achieved in carrying out the procedure on a commercial scale.

A further feature of the invention is represented by the roller 13, which has a specially grooved surface configuration. As will be noted, the surface of this roller is provided with oppositely angled groovings of a spiral character, extending in opposite directions from the center of the roller. These groovings are of such character as to exert a frictional force upon the web passing around the roller 13, this force initiating the convergence of the web toward a compacted formation, as indicated at 14.

In connection with the groovings referred to, it may be noted (merely by way of example) that a spiralling of roughly three complete turns per inch of longitudinal length of the roller is adequate for the purpose, and that grooves having flat bottoms and a depth of as little as of an inch have proven to be satisfactory. The grooves may be /8 of an inch in width, and the ridges between them (also having flat top surfaces) may be approximately of an inch wide. The important feature of the configuration is, of course, the opposite inclinations of the spirals, outwardly from the center of the roller, whereby the mutilated corrugated web is frictionally urged toward a converging path of travel as it changes its direction in passing around the guide roller. The roller surface is preferably of brass, and if desired the entire roller 13 may 'be formed of an element of suitably machined brass tubing.

The filters produced by the described process and structure are unusually uniform, and the filtering action is highly efiective without retarding the draft through the cigarette of which the filter forms a part. This desirable result is achieved, in part, by the improved procedure herein described, and the special manner in which the web of fibrous material is lacerated and distorted to disarrange and displace its fibers.

While only a single embodiment of the invention has been illustrated and described, it is obvious that the invention is not to be restricted thereto, but is broad enough to cover all structures and procedures which fall within the scope of the appended claims.

What is claimed is:

1. In an apparatus for conditioning a fibrous Web to separate its fibers without destroying the transverse continuity of the web, a pair of mutilating rollers mounted for rotation on parallel adjacent axes, said rollers having each the same circumferentially grooved configuration defining closely spaced alternate ridges and valleys, said rollers being arranged in nested proximity with the ridges of each roller extending into the valleys of the other, each ridge having a cross-sectional contour which exposes at least one sharp edge, each valley having a cross-sectional contour which presents a relatively fiat surface in opposition to each ridge edge, the perpendicular distance from said relatively fiat surface to said ridge edge being smaller than the axial distance between adjacent ridges of said nested rollers, and means for passing the web to be treated between said rollers, whereby the web becomes irregularly torn along the regions constrained to squeeze between the sharp ridge edges and the relatively flat surfaces opposed thereto.

2. In an apparatus for conditioning a fibrous web to separate its fibers without destroying the transverse continuity of the Web, a pair of mutilating rollers mounted for rotation on parallel adjacent axes, said rollers having each the same circumferentially grooved configuration defining closely spaced alternate ridges and valleys, said rollers being arranged in nested proximity with the ridges of each roller extending into the valleys of the other, each ridge having a flat outer face and sharp lateral edges, each valley having a cross-sectional contour which presents a relatively flat surface in opposition to each ridge edge, the perpendicular distance from said relatively fiat surface to said ridge edge being smaller than the axial distance between adjacent ridges of said nested rollers, and means for passing the web to be treated between said rollers, whereby the web becomes irregularly torn along the regions constrained to squeeze between the sharp ridge edges and the relatively flat surfaces opposed thereto.

3. In an apparatus for conditioning a fibrous web to separate its fibers without destroying the transverse continuity of the web, a pair of mutilating rollers mounted for rotation on parallel adjacent axes, said rollers having each the same circumferentially grooved configuration defining closely spaced alternate ridges and valleys, said rollers being arranged in nested proximity with the ridges of each roller extending into the valleys of the other, each ridge having a fiat outer face and sharp lateral edges, each valley having a smoothly curved concave crosssectional contour which presents a relatively fiat surface in opposition to each ridge edge, the perpendicular distance from said relatively fiat surface to said ridge edge being smaller than the axial distance between adjacent ridges of said nested rollers, and means for passing the web to be treated between said rollers, whereby the web becomes irregularly torn along the regions constrained to squeeze between the sharp ridge edges and the relatively fiat surfaces opposed thereto,

4. In an apparatus of the character described, a pair of mutilating elements mounted for rotation on parallel adjacent axes, means for passing a fibrous web between said elements, said elements being adapted to separate some of the fibers of said web without destroying the transverse continuity of the web, and means for initiating convergence of said mutilated Web toward a compacted formation, said means comprising a roller positioned to guide the mutilated web through a sharp change of direction, said roller having a grooved surface configuration 5 which includes oppositely angled spiral groovings extending in opposite directions from the center of said roller and said roller being so rotated that it exerts frictional forces upon the web in directions toward the center of said roller thereby tending to reduce the Width of said 10 web.

References Cited in the file of this patent UNITED STATES PATENTS Hatter Mar. 4, 1924 Greis Dec. 1, 1925 Cannard Sept. 22, 1931 Antonsen Dec. 17, 1933 Cumfer Oct. 17, 1939 Marogg Sept. 2, 1958

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