US3297512A - Apparatus for forming rods from continuous filament tow - Google Patents

Description

10, 1967 P. 1.. COBB, JR.. ETAL 3,297,512

APPARATUS FOR FORMING RODS FROM CONTINUOUS FILAMENT TOW Filed Dec. 26, 1962 3 Sheets-Sheet 1 .Ph ara L.C'0bb,Jr. Joel BdS'teVens INVENTORS BY N @(LQQ 1967 P. COBB, JR., ETAL 3,297,512

APPARATUS FOR FORMING RODS FROM CONTINUOUS FILAMENT TOW Filed Dec. 26, 1962 3 Sheets-Sheet 2 ALTERNATE- ELECTRIC RESISTANCE HTR.

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PharaL. Cobb]: Joe t 13.8 levens INVENTORS .A'I' TORNEYS Jan. 10, 1967 P. L. COBB, JR. E I'AL 3,297,512

APPARATUS FOR FORMING RODS FROM CONTINUOUS FILAMENT TOW Filed Dec. 26, 1962 s Sheets-Sheet 5 Phurc L.Cobb,Jr. Joel B. Stevens INVENTORS BY M ATTORNEYS United States Patent 3,297,512 APPARATUS FDR MERE ENG RQDS FROM CONTINUOUS FILAMENT TOW Phara L. Cobb, Jan, and .loel B. Stevens, Kingsport. Tenn, assiqners to Eastman Kodak Company, Rochester, N.Y., a corporation of New .lersey Filed Dec. 2-6, 1962. Ser. No. 246,954 3 Claims. (Cl. 156-433) This invention relates to process and apparatus for making rods from bundles of filaments. More particularly, this invention concerns the preparation of unwrapped rods composed of a multiplicity of crimped continuous filaments randomly bonded together to form a firm unitary structure.

Filter rods for cigarettes have been made successfully according to Crawford et al. US. Patent 2,794,480. Here the filamentary material is wrapped in a sheath. Firmness results from the bonding of the filaments, one to another, at a multiplicity of randomly spaced zones of contact. Preferably the bonding results from the action of a plasticizer which acts on the filaments after the material has been shaped and contained by a paper wrapper.

Rods for cigarette filter and other purposes have also been made by the method and apparatus disclosed by Cobb et al. in Us. patent application Serial No. 814,649, now US. Patent No. 3,079,978. Here the filamentary material is formed into a rigid structure by heat as the filaments are drawn through a rigid die. It is desirable in such rods that the filaments retain a high proportion of their initial crimp. The material is pulled through the die and to avoid high tension which will straighten out the filaments, the rigid die is of necessity, relatively short. This in turn requires a high rate of heat input to the die. As a result, the structure obtained by the Cobb et a1. process just referred to may have an impervious skin composed of fused filaments coupled with random bonding of the filaments Within the core of the rod. The amount of bonding may decrease as the distance from the outer surface increases.

It has become apparent that structures as under discussion herein similar to a cigarette filter but of a different size or the like are useful for filtering other gases or liquids or for wicking applications. Generally, for such applications, a wrapper or impervious skin is unnecessary or even may be undesired. Hence, it is apparent that the development of further processes and apparatus for the production of rods of the class indicated wherein such rods can be made with a wider range of properties represents a highly desirable result. After further investigation we have found procedure whereby such type rods may be made in greater variety and with a wider range of properties as compared with the rods as heretofore made and as referred to above.

This invention has for an object to provide process and apparatus for making rods useful for filters and other purposes. A particular object is to provide a rigid, unitary structure of crimped filaments wherein the material is not encased in a wrapper of any kind but the filaments are bonded to one another randomly and relatively uniformly throughout the cross-section of the rod. A further object is to provide an apparatus arrangement whereby bonding of filaments making up a rod may be controlled in a certain manner to give the desired bonding from surface to center. Another object is to provide a simple and convenient process for carrying out the foregoing. Other objects will appear hereinafter.

For assistance in understanding our invention, reference is made to the attached drawing forming a part of the present application. In this drawing FIG. 1 is a semidiagrammatic side elevation view largely in perspective of the over-all association of parts which would be used for carrying out our invention.

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FIGS. 2 and 3 are detailed views in section illustrating types of heating or cooling units which may be used in our process.

FIG. 4 is a side elevation view showing in some detail the preferred heating device with continuous belt which is used in our apparatus setup and with respect to which the instant invention is especially concerned.

FIG. 4A is an enlarged portion of part of FIG. 4 showing in more detail tongue 9, an extension of funnel 8 which extends through the tapered entrance portion (funnel) 12 of forming member 10 and along with belt 11 helps guide continuous filament tow 13 into forming member 10.

FIGS. 5 and 6 are detailed views in section of a type similar to FIGS. 2 and 3 illustrating other heating device constructions.

FIGS. 7, 8, and 9 are transverse sections taken along lines A-A and BB and C-C, respectively, of FIG. 4a, With numeral references identical to those of FIG. 4. FIGS. 7, 8, and 9 show how tongue 9 guides filaments 13 into belt 11 as it changes from a fiat cross-section to an annular one, tongue 9 insuring that all filaments are enclosed in belt 11 until a complete single circular cross-section of filaments is attained.

Referring to FIG. 1, a preferred means of carrying out our invention is illustrated. Crimped, continuous filament yarn in tow form 1 is withdrawn from a supply source such as a commercially available bale. If the cross-section of the rod desired requires more filaments than are contained in one tow, two or more tows may be used as illustrated. The tows are drawn through a banding jet 2 as disclosed in Stevens US. Patent 2,908,045 to form a flat ribbon free of folds or twists and of uniform width and thickness, and over a suitable guide 3 by a pair of feed rolls 4. One or both of these rolls may have a resilient cover such as rubber or other cover or special configuration to provide a positive nip which will feed the tows at a suitable rate. The banded tow is withdrawn from the feed rolls, passing over and under wick-type plasticizer applicators 6 and 6a, by a hustled, cylindrical fluffing jet 7. The plasticizer applicator and flufiing jet may be of the type disclosed by Caines, Dyer, and Pannill, our co-workers, in US. patent application Serial No. 27,091, now US. Patent No. 3,099,594.

The plasticized, bloomed tow is then drawn into a forming die, generally indicated as 10, of the desired size and shape through condensing funnel 8 by endless belt 11. To produce a cylindrical rod as depicted, the endless belt is formed into a hollow cylinder by the die. The belt width and thickness and the die dimensions are so chosen that the edges of the belt meet in a butt joint, forming a hollow cylinder with an inside diameter essentially equal to the desired diameter of the rod.

An important feature of the condensing funnel is a tongue 9, as clearly shown in FIG. 4, preferably formed of thin, flexible metal, which extends inside the belt where the edges are being brought together to keep filaments from getting caught between the edges of the belt as they gradually close. The entrance end of die 16 may be provided with a converging funnel section 12 to permit smooth shaping of the belt and final compaction of the tow. The die may be divided into sections; the first section 13 being heated, the third section 15 being cooled, and the intermediate section 14 having neither heating nor cooling. Furthermore, to facilitate the use of a seamless, endless belt all sections of the die are divided longitudinally into sections (1311 and 13b) as indicated by the enlarged crosssectional view, FIGURE 2. As already suggested, an alternate construction, also permitting the use of a seam less belt, is shown in FIGURE 3.

In the above general description of our invention which gives an over-all understanding of our invention some of the parts and their functioning may be constructed as already described in detail in the above referred to Cobb et al. patent and said application Serial No. 27,091. Hence, detailed description of such parts herein is unnecessary. Accordingly, the description which now follows is directed in particular to process and apparatus features and improvements over prior procedures and apparatus.

Referring again to Fig. 1, the belt is moved by drive pulley 16 and otherwise guided by idler pulleys 17a, 17b, 17c, and 17d. The finished, bonded rod 18 emerges from the discharge end of the belt 11a. Since the process operates at a relatively low speed, the rod may be cut off manually or if desired, an automatic cut-off (not shown) may be added to the unit. Resonable care in handling the freshly formed rod is desirable.

The specifications for the endless belt are important. A cotton belt will withstand the temperatures involved. It preferably will be thick enough to retain a cylindrical form in the die. The inner face should have a close weave as filaments will adhere to the surface if it is too rough. Impregnation of the inner surface with neoprene composition or other known and commercially available material unaffected by the plasticizer and heat is a useful feature.

A particular arrangement of the forming device is shown in FIGURE 4. Here, as the rod emerges from the belt at zone 11a, it enters a final sizing or polishing die 18. Preferably this die is a seamless metallic tube with a polished bore. It also may be surrounded by a cooling jacket although this is not essential. This die will impart a smooth surface to the rod and also provides close control of the diameter. Means to pull the rod through the finishing die is desirable. This means may consist of one or more pairs of grooved rolls 19 or a short belt which encompasses the rod as the forming belt does.

Suitable means to drive forming belt 11 and at least one member of feed roll pair 4 would be included. The drive should preferably permit variations in the speed of the forming belt and also provide for adustment of the feed roll speed relative to the belt speed. Metering pumps which provide a positive, non-pulsating feed of plasticizer to each wick of the plasticizer applicators 6 and 6a are also desirable. Drive mechanisms and like parts to accomplish all of the above are known or shown in the companion patent and application referred to above; hence, further description herein is unnecessary. Heating and cooling of the appropriate sections of the forming die are accomplished by conventional means. For example, the heated section may utilize electrical resistance heamrs, a circulating hot fluid, or infrared heat. It is desirable to insulate the heated section to minimize heat loss, to provide closed temperature control, and to protect the operator. Cooling is accomplished with circulating cool gas or fluid. FIGS. 2 and 3 suitably illustrate such aspects.

Temperature sensing elements are provided to permit control of the temperatures along .the forming unit. Thermocouples, thermoelectric resistance units or other temperature sensing elements are appropriate. Indicating units with manual controls may be utilized or automatic temperature regulation may be provided. Inasmuch as such items are known there is no need to show and describe in further detail.

From the foregoing description it is believed that it is already apparent to a substantial event how our new apparatus may be constructed and useful processes carried out therein. Nevertheless, further description will be set forth concerning the general operation of our process. Referring to FIG. 1, a suitable supply of the filaments or fibers to be used will be obtained as indicated at 1. While, as noted below, we prefer a high quality crimped continuous cellulose acetate tow of a total denier up to 400,000, a denier per filament up to 16 and a crimp per inch of 4-18, other filament bundles may be used.

For example, polyolefin filaments with a crimp up to 40 c.p.i. may be processed by the present invention as may be filament bundles comprised of polyester. Under certain circumstances, viscose tows, particularly where they have been coated with cellulose acetate or other thermosensitive materials, may be efficiently processed in our apparatus.

The fibrous or filamentary material in suitable quantity from one or more packages depending on the size of the rod and the like specifications of the rod to be produced would be withdrawn from the supply and fed to the process. The filament bundles are banded at 2 and fed through addendum applicators 6 and 6a depending upon the subsequent treatment contemplated, the composition of the filaments being processed and the specific nature of the rod being prepared.

We prefer in general to jet treat the bundle of filaments in jet 7 of FIG. 1. The type of jet used may be as described in the aforementioned application Serial No. 27,091. Or, other methods of opening up the filament bundles may be used. An example of such other method comprises a pair of small pretension rolls in series with a single roll pair operating at differential speeds. In any event, the filament bundles are banded, fiuifed and interlaced as desired and then fed into entrance 8 of the forming device comprising the particularly novel portion of our invention.

In this arrangement, as illustrated in FIG. 4, various treatments may be applied in a continuous manner to produce rods with properties varying from fused skin and no internal bonding to rods with no noticeable surface skin or sheath but with internal bonding. This and other features will be further apparent from a consideration of the following examples set forth for illustrating certain of our preferred embodiments.

Example I Rods were made by drawing five cellulose acetate tows, each 5 d./f.-50,000 t.d., regular cross section, 13 crimps per inch through a 13" wide banding jet 2 located over the bales. Air at 2.1 p.s.i.g. was supplied to the banding jet. The feed rolls ran at a linear speed of 7 ft./min. Glycerol triacetate, a plasticizer for cellulose acetate, was applied to the banded tow by two 13 inch long felt wick type applicators, each fed by a positive metering pump. The rate of application was 15 parts of plasticizer per parts of cellulose acetate by weight. The treated tow was bloomed or fiuflfed in a large cylindrical, bustled fiufiing jet operating at 7 p.s.i.g. air pressure. The effective length of the forming section 10 was four feet with an internal diameter of 0.770 inch. The prepared tow was carried through the die at a speed of 6.8 ft./min. by an endless cotton belt 2" wide by thick. The dwell time in the forming section was 35.3 seconds. The first three feet of the die was heated with electrical resistance heaters to temperatures ranging from 219 F. near the entrance to 346 F. at the discharge end of the heated section. The final foot of the die was not heated but dissipated heat by convection and conduction. Its temperature ranged from 280 F. to 245 F.

The resulting product was a well-bonded, firrn rod 0.580" in diameter with a density of 0.287 gms./cc. or a weight of approximately 50 gms./ M.

Example 11 A composite tow of 5 d./f., 250,000 t.d. was used as described above. A cooling section was added to the forming unit. The temperature of the heated section ranged from 290 F. near the inlet to 455 F. at its discharge end. The final section was cooled by circulating water through a jacket and the exit temperature was 143 Fr The die and belt dimensions were as described in Example I. The lengths of the forming sections were as follows:

This arrangement of the apparatus permitted a belt speed of 13.8 ft./min. and a feed roll speed of 14.4 ft./min.

The resultant rod had a density of 0.293 gm./cc. or 49.4 gms./M.

The density of our rod can be changed by changing the speed of the feed rolls relative to the belt speed. If the feed roll speed is decreased while holding the belt speed constant, the density of the rod will be reduced. The diameter of the rod will also be somewhat less. Greater changes in rod density are effected by changing the total denier of the tow. Substantial changes in rod diameter are accomplished by selection of the proper belt width and die diameter.

Our invention is not limited to plasticizing and flufiing the tow as described above. As already mentioned, any of several methods of opening and applying addendum to tow for the production of rods can be used. In some instances it will be necessary to alter the dimensions of the equipment to accommodate the total tow denier utilized.

Likewise, our invention is not limited to the production of cylindrical rods using one belt to convey the bloomed tow through the forming section. FIG. 5 shows in cross section how two belts may be used in the forming section to produce a cylindrical rod, each belt covering one-half the periphery of the rod.

FIG. 6 depicts an arrangement which will form a rod of quadrilateral cross-section. As may be seen, four belts 21, 22, 23 and 24 would be used. It will be appreciated by those with mechanical skill that the mechanical arrangement of multiple belts operating in the diiferent planes involved may be accomplished similar to the belt construction of FIG. 4. The design of a condensing funnel with tongue to keep tow out of the cracks as the belts draw together is also an item which may be varied to handle the situation when more than one belt is used.

Although the invention has been described in detail with reference to preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined by the appended claims.

.We claim:

1. A heated forming die adapted for forming a substantially rigid filter rod from continuous filament tow having (1) a tongue positioned at the entrance thereof whereby filament clogging in said die is substantially eliminated, (2) a continuous belt in association with said die, (3) means for moving said belt continuously through said die and wrapping said belt in a cylindrical configuration within said die as it moves therethrough and (4) means for unwrapping said belt as it leaves said die at an opposite end thereof, said heated forming die comprising three sections, the first of which is an entrance end with a converging funnel section containing the tongue whereby smooth shaping of the belt is permitted, said entrance end being heated, the second of which is an unheated and unoooled intermediate section and the third of which is a cooled section forming an exit portion of said die.

2. The apparatus of claim 1 wherein a central axial portion of the heated die comprises a rectangle adapted for formation of the four sides thereof by four separate belts joining at the four corners of said rectangle.

3. The apparatus of claim 1 wherein a central axial portion of the heated die comprises a cylinder with open ends so as to enable forming of a peripheral portion of the cylinder by at least one belt shaped in substantially cylindrical form.

References Cited by the Examiner UNITED STATES PATENTS 2,796,810 6/1957 Muller 9239 2,813,051 11/1957 MacHenry 156201 2,900,988 8/1959 Crawford et a1 131208 2,964,440 =12/ 1960 Stevens 156178 3,039,908 6/1962 Parmele l56200 3,050,430 8/1962 Gallagher 156-166 3,130,104 4/ 1964 Lewis et al 156-443 X 3,173,188 3/1965 Wexler 281 EARL M. BERGERT, Primary Examiner.

R. I. CARLSON, P. DIER, Assistant Examiners.

Claims (1)

1. A HEATED FORMING DIE ADAPTED FOR FORMING A SUBSTANTIALLY RIGID FILTER ROD FROM CONTINUOUS FILAMENT TOW HAVING (1) A TONGUE POSITIONED AT THE ENTRANCE THEREOF WHEREBY FILAMENT CLOGGING IN SAID DIE IS SUBSTANTIALLY ELIMINATED, (2) A CONTINUOUS BELT IN ASSOCIATION WITH SAID DIE, (3) MEANS FOR MOVING SAID BELT CONTINUOUSLY THROUGH SAID DIE AND WRAPPING SAID BELT IN A CYLINDRICAL CONFIGURATION WITHIN SAID DIE AS IT MOVES THERETHROUGH AND (4) MEANS FOR UNWRAPPING SAID BELT AS IT LEAVES SAID DIE AT AN OPPOSITE END THEREOF, SAID HEATED FORMING DIE COMPRISING THREE SECTIONS, THE FIRST OF WHICH IS AN ENTRANCE END WITH A CONVERGING FUNNEL SECTION CONTAINING THE TONGUE WHEREBY SMOOTH SHAPING OF THE BELT IS PERMITTED, SAID ENTRANCE END BEING HEATED, THE SECOND OF WHICH IS AN UNHEATED AND UNCOOLED INTERMEDIATE SECTION AND THE THIRD OF WHICH IS A COOLED SECTION FORMING AN EXIT PORTION OF SAID DIE.

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