US3363323A - Method for drying of the interior of a traveling flexible sleeve - Google Patents

Description

Jan. 16, 1968 0. A. BRAFFORD 3,36

METHOD FOR DRYING OF THE INTERIOR OF A TRAVELING FLEXIBLE SLEEVE Filed April 9, 1965 INVENTOR. flan 4Z0 A gwfi'aw 1g g E E 5 Z ATTORNEYS United States Patent 3,363,323 METHOD FOR DRYING OF THE INTERIOR OF A TRAVELING FLEXIBLE SLEEVE Donald A. Bralford, Beloit, Wis., assignor to Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Filed Apr. 9, 1955, Ser. No. 446,852 1 Claim. (Cl. 34-6) The instant invention relates to a drying method and more particularly to a method for the drying of the interior of a traveling flexible sleeve, preferably a flexible sleeve of plastic material.

It is known that plastic materials are cast from their molten form through a generally circular orifice with a certain predetermined nominal amount of gas pressure in the interior thereof continuously and directly into a liquid which effects the solidification of the plastic material into its sleeve form. Generally, the patent literature shows this arrangement with the orifice for feeding the molten body of annular plastic material directly into such liquid with a pair of nip-defining rolls submerged in the liquid so that there will be continuously maintained a liquid level along the outer periphery of such plastic sleeve and also the nip-defining rolls will maintain a column of comparable if not the exact height of liquid in the interior of such sleeve or primarily annular plastic material which is collapsed at such nip. This column of liquid is ordinarily water and so is the liquid which is in contact with the outer periphery of the sleeve. Water or whatever cooling material is used, however, will generally be used to contact both the inner periphery and outer periphery of the plastic material as it is converted from molten to solid sleeve and subsequently when it is collapsed by the nipdefining rolls. The nip-defining rolls tend to hold the column of liquid in the interior thereof at a predetermined level and this overall arrangement is shown in any number of prior art patents.

It So happens that particularly in the case of plastic materials the amount of pressure which can be applied at the submerged nip rolls is limited by that which the plastic itself can stand, even though an ideal arrangement would call for 'sufiicient pressure to preclude any of the liquid from passing through the nip in the interior of the collapsed sleeve. Instead, however, a certain amount of liquid does pass through this nip in the interior of the collapsed sleeve andthis liquid material (usually water) is not desirable and subtracts from the marketability of the plastic, whether or not the plastic is ultimately slit or otherwise treated during whatever conventional or nonconventional conversion procedures the plastic sleeve might be subjected to.

Generally some procedure, method or apparatus must be used to try to dry and/ or remove the liquid that was originally in the column maintained within the sleeve at the time of conversion from molten to solid materials and, as those skilled in the art will appreciate, this type of removal of liquid is not particularly easy because it is rather diflicult to reach the interior of such sleeve with any sort of device.

The instant invention, however, provides a unique method of disposing of the so-called liquid impurities or drying the liquid by removal thereof from the inner periphery of this sleeve subsequent to initial collapsing of the same by the submerged nip rolls in the bath in which the plastic sleeve undergoes conversion from molten to solid plastic. Again, the prior art has shown anynumber for accomplishing this particular procedure and many of these devices include slitting of the plastic sleeve at some area remote from the aforesaid bath in which the annular molten plastic is converted to a solid plastic sleeve; but

all of these devices appear to leave something to be desired by way of commercial practicability or otherwise.

In the instant invention, however, there has been provided a unique method for effecting removal of the very small amount of liquid which passes through the initial submerged nip in the so-called phase change bath, which is an adequate term to define the bath which contacts both the inner periphery and exterior periphery of the molten plastic material for purposes of converting the same from its initial molten or liquid condition to its comparatively solid (even though flexible) condition at the time that it is collapsed .by the initial submerged nip between rotary members or rollers in such bath. The instant invention is not concerned with the specific details of this arrangement.

Moreover, the instant invention is not concerned with devices which may be used to remove the liquid bath from the outer peripheral surface of such sleeve either in its expanded or its collapsed condition after it is removed from the so-called phase change bath previously described. Instead, the instant invention is concerned with the more fundamental and much more difficult concept of removing the minute amounts of liquid which escape from the column contacting the inner periphery of the liquid in such phase change bath through the submerged initial collapsing nip.

Typical examples of prior art disclosures which show the phase change bath and the overall assembly which has just been described include the following patents:

Voss, 1,942,990, Jan. 9, 1934; Weingand, Re. 19,329, Sept. 25, 1934; Wiley, 2,409,521, Oct. 15, 1946; Grotenhuis, 2,450,457, Oct. 5, 1948; Stephenson, 2,452,080, Oct. 26, 1948; Francis, 2,476,140, July 12, 1949; and Irons, 2,541,064, Feb. 13, 1951.

Also, various wiping and/or drying means are knownto be used to remove the phase change bath liquid from the outer peripheral surface of the plastic sleeve either in collapsed or expanded condition thereof.

With respect to the interior peripheral surface of such sleeve, however, it must be appreciated that only traces of the liquid from the column of liquid of the phase change bath ordinarily maintained by the submerged roll nip are able to pass through this nip and be retained on the inner periphery of the plastic sleeve, whether'or not it is collapsed. The instant invention relates to methods and apparatus for effecting the removal of these traces which subtract from the marketability of the solid flexible plastic material, whether in closed sleeve condition or in slit opened single sheet condition. It will be appreciated that simply slitting the sleeve to obtain a single sheet may possibly afiord a means of reaching the previously defined inner periphery of the sleeve and removing these traces of liquid, but in many instances this does not happen to be the desirable procedure, or, alternatively, it is preferable to remove these traces of liquid from the inner periphery of the sleeve before slitting and/or other conversion procedures. The conversion procedures also are not considered to be an essential part of the instant invention, although it is certainly expected that at least conventional conversion will occur ultimately in the treatment of the sleeve. Such conversion may merely involve the creation of superimposed collapsed sleeve sections in the stack or the creation of a roll of collapsed sleeve for transportation or other subsequent more detailed conversion; or the conversion may actually involve the slitting of the sleeve and reslitting of the same repeatedly to obtain a plurality of single sheet widths of the desired width which again may be formed into superimposed generally planar stacks, rolls, etc.

Instead, the instant invention affords a novel and unique method that is positioned between the previously 3 discussed submerged initial nip-defining rolls in the phase change bath and the various conversion devices which may be used in any number of conversion processes.

In substance, the instant invention involves an arrangement whereby particulate material of slight but still effective weight is incorporated within the sleeve and is permitted to engage the inner periphery thereof such that the collapsed sleeve is again re-expanded to at least a certain extent and this particulate material serves to continuously pick up the traces of liquid passing by on the inner periphery of the sleeve so that the inner peripheral surface of the sleeve is rendered free from such liquid prior to the so-called conventional conversion station, no matter what procedure may be contemplated for conversion. It will be appreciated that one cannot use merely any type of liquid capturing device to engage the inner periphery of the sleeve at this stage in the production of a closed plastic sleeve, because of a number of practical reasons which include inability of certain materials to actually contact all areas of the inner periphery of the sleeve, inability of certain materials to remove such traces of liquid for any practical length of time during operation, inability of such devices to actually carry away the traces of liquid removed from the inner peripheral surface because of lack of escape arrangements, etc. Accordingly, the instant invention is unique in that it affords an answer to these various practical problems. In fact, one of the initial more practical problems is the changing of the flattened or collapsed tube which has the form of a pair of sheets with the inner peripheral surface forming the contiguous faces thereof in actual contact with each other; and the problem of merely separating these so-called contiguous faces of the sheets of the previously identified inner periphery of the plastic sleeve is not simple when one considers that it may be desirable, and in the case of the present invention it is not only desirable but possible, to effect this removal of traces of liquid without actually slitting the sleeve and opening the same to form a single sheet which may then be wiped free of such traces or may otherwise be treated for removal of such traces of liquid carried thereon.

It is thus an important object of the instant invention to remove traces of liquid from the inner periphery of a traveling closed sleeve of material without slitting the same continuously and by the use of appropriate means which are not otherwise harmful to the sleeve itself or to the inner periphery thereof. It should also be mentioned that the liquid which forms the traces on the inner periphery of the sleeve is usually so difiicult to volatilize and the plastic sleeve itself is usualy thermoplastic in nature such that it is rendered molten without too much difliculty, such that simply heating of the sleeve will not help in this situation. Moreover, the heating of the sleeve would possibly serve to volatilize these traces of liquid but escape of such vaporized traces of liquid still remains as a practical problem, which would not be solved by mere heating and which is solved in the practice of the instant invention.

It is, therefore, an important object of the instant invention to provide a method for removing traces of liquid for a traveling sleeve at the inner periphery thereof without disturbance of the sleeve structure, including slitting of the sleeve.

Other and further objects will become apparent to those skilled in the art from the following detailed disclosure thereof and the drawing which is here shown in generally schematic fashion.

Referring to the drawing, it will be seen that the collapsed sleeve is indicated as initially approaching the device at and then passing through a series of serpentine convolutions 10a, 10b, 10c, 10d, etc. which serpentine convolutions are defined by or effected by passing the collapsed sleeve 10 over first an upper roll 11a and then a lower roll 11b, then an upper roll 110, then a lower roll 11d, and so on about rolls v11e through 11k 7 tension reduction in the tube portion 10g such that the J in a system sometimes referred over-all as a festoon-construction for tension. It will be appreciated that the upper rolls 11a, 110, 11a, 11g and 11h are equipped for movement toward and away from the lower rolls 11b, 11d, 11 11g, etc. and in this way the overall tension onthe collapsed sleeve 10 is maintained relatively constant as it passes through such festoon which is indicated generally by the reference numeral 11, the collapsed sleeve 10 is maintained at the desired, usually constant tension from roll to roll on each of the rolls 11a, 11b, etc. The tension maintenance devices are indicated herein by double headed arrows marked d in each case and need not be described in further detail herein for the reason that these devices are all well understood by skilled workers in this and many other arts. The lower rolls 11b, 11d, etc. could also, of course, be equipped with means for moving the same so that they too'could cooperate in or actually effect the desired tension control but this is ordinarily not practical and, in fact, the lower rolls 111) through 11g are often maintained in a bath B of additional cooling liquid which is shown here schematically in order to further reduce the temperature of the collapsed sleeve 10. It will be appreciated that the sleeve 10 is not collapsed until the inner periphery has substantially lost its tendency to effect sticking of contiguous collapsed faces thereof, but additional cooling may often be desirable for any number of reasons which those skilled in the art will appreciate. The problem is that the inner periphery of this collapsed plastic tube still maintains traces of liquid that were carried through the initial submerged nip (not shown) from the initial column of phase change liquid in the first bath into which the molten annular plastic body (again not shown) was originally fed in the formation of the plastic tube 10.

It will also be appreciated that if there is a break in the collapsed plastic tube, for example, beyond the festoon in the region 10d even in the earlier portions of the festoon 11, the devices a originally intended to maintain the, desired, presumably constant, tension may then be used to quickly take up slack and otherwise generally maintain the collapsed tube 10 in a desired condition for patching or whatever maintenance might be required in order to put the collapsed tube 10 back together in one form or another and reestablish its progress through the festoon 11. Y

It will also be noted that the collapsed tube passes around a lower roll 11k in a region designated 10a and then through first and second nip-defining rolls 12 and 13, respectively and subsequently through third and fourth'nip-defining rolls 14 and 15 respectively, from which the collapsed tube, then designated 10 continues onto the conversionsystem (not shown). In the region between the nip N1 defined by the two rolls 12 and 13 and the second nip N-2 defined by the two rolls. 14 and 15, it will be seen that the previously collapsed plastic tube undergoes an expansion and is designated 10g. It will be appreciated that this expansion does not necessarily make the tube completely annular in configuration or cross section, but it does expand the same between the two nips N-1 and N-2. Also, in order to guide the expanded tube 10g into the second nip N-2 it will be seen that side boards or guides 16 and 17 that are generally commensurate with the collapsed width of the tube 10 serve to aim the tube 10 toward'the second nip N-2. These guides 16 and 17 may or may not actually contact the outer'periphery of the tube 10, but usually they do or they are provided with some sort of a blanket of gas or similar non-deleterious fluid which might serve to avoid direct contact between the solid side boards 16 and 17 but would materially assist in the guiding function which is intended for these side boards 16 and 17.

It will also be noted that the nip N+2 is positioned substantially above the nip N-l and these nips are spaced apart in such a manner as to permit a certain amount of tube is permitted to change from its originally collapsed condition previously described to a condition in which it is opened at least to some extent. The tube itself is formed of a solid elastomer in the preferred embodiment of the invention, so it is not necessary actually to have the positioning of the nips N-l and N-Z in such a relation of spacing that a collapsed tube would not pass therebetween at substantially the same tension as is used in the festoon 11, although this certainly is helpful. Also, the tube in both collapsed and expanded forms, e.g. at a and 10g, is made of flexible material and it is thus capable of going through the various convolutions and/ or direction changes herein described without any harm thereto. In fact, the flexibility is such that there is no harm to the tube and its modulus of elasticity and/or tendency to rupture is not exceeded by any expansion which may take place within the region 10g in the preferred operation of the invention which will be described in further detail hereinafter.

It will further be understood that the festoon rolls of the sequence 11a, etc. and the nip-defining rolls 12 through are ordinarily driven as a group or at least partially so as to maintain the desired linear speed of the tube 11 in both collapsed and open form through the overall assembly, although such drive means are also well understood by the skilled workers in the art and need not be described in any detail herein. In the drawing, the drive means are indicated in the series R through R generally schematically, in view of the fact that the skilled worker will readily recognize the nature and character thereof and will not need any disclosure of further details to comprehend the same. More or less drive means may be used with the various rolls described herein to carry out the intended function, which is merely that of driving the tube 10 at a generally constant linear speed while maintaining the desired tension, which is generally constant in the festoon and which is somewhat increased usually between the nips N-l and N-2.

Referring now to the means for removing the traces of liquid that may be carried on the interior periphery of the tube 10, it will be seen that within the opened tube portion 10g there is shown a myriad of fine particles which actually form a bed of particles 20 defined by the interior of the expanding tube 10g leaving the oflf-running side of the nip N-l. These particles will, of course, have at least sufliciently great weight to overcome whatever pressures there might be in the ambient atmosphere and/or in any atmosphere, air jets, or other fluid means which might be driven against the outer periphery of the plastic sleeve 10 in the region 10g, so that the particle bed 20 will in fact assist in if not entirely effect the expansion of the collapsed tube to the form shown in the drawing. The particles in the bed 20 are, of course, shown in exaggerated size. These particles need not be homogeneous in character and, in fact, if air jets and the like are to be used to remove traces of, for example, moisture from the outer periphery of the sleeve in the region of 10g (by virtue of the bath B wetting the same), then it might be desirable to include a certain amount of shot or other relatively heavy metal spheres as a part of the overall bed 20. In any event, the bulk of the bed 20 is such that it does serve to open the collapsed tube in the region 10g at the off-running side of the first nip N1. In addition, the nature and character of the particles in the bed 20 is such that they do not simply stick to a wetted portion of the inner periphery of the tube and rise upwardly to plug or otherwise interfere with a nip function at the second nip N2 between the rolls 14 and 15. Of course, the two nips N-tl and N-Z need not be superimposed and all that is required of the second nip N2 and the rollers 14 and 15 is that they do not pass particles from the bed 20 and they do not permit such particles to harmfully act on the inner periphery of the sleeve portion 10g. Thus in the case of a pair of generally horizontal nips N-l and N4 or even a pair of nips where the nip N-l is above the nip N-2, the essential requirement would be that the particle size and shape would be preferably generally spherical and of such size that it would not pass through the second nip N-Z or partially clog the same in such a way as to cause marking, grooving or other harmful eflect on the interior or the overall body of the tube portion 10g that passes through and is collapsed at the second nip N2.

In the ideal situation the bed 20 is maintained in particulate generally physically fluid state at a relatively lower level just above the nip N-l, in a state of continuous circulation such that it does not even approach the second nip N-2 and any of these various undesirable possibilities are thereby avoided. As here shown, the level L of the fluid bed 20 is actually below the midpoint between the nips N- l and N2 and substantially no chance of any individual particles being carried upwardly to the second nip N2 is afforded. On the other hand, the particles as individuals in the bed 20 are intended to carry out the function of removal of the traces of liquid which had previously collected on the surface of the inner periphery of the tube as it passed through the submerged nip in the phase change bath, where the submerged nip actually maintains a column of phase change liquid in the interior of the tube as well as at the exterior thereof (during its change from molten to solid form). Such liquid is, for most practical purposes; water but at least it is a liquid that is substantially insoluble in the body of the solid plastic tube 10 and the solid plastic tube 10 is, likewise, substantially insoluble in such liquid in at least the trace quantities that appear in the region 10g as well as in the previously mentioned phase change bath (not shown). On the other hand, a nominal amount of adherence between at least some of the particles in the bed 20 and the inner periphery of the tube portion 10g is not undesirable.

This nominal amount of adherence can be achieved by virtue of the fact that the traces of liquid on the inner periphery of the tube in the region 10g may be, for example, water and the particles may be solids which tend to pick up water by capillary action or similar phenomena, but which have sufliciently low weight that they have a tendency to be more or less continously moved upwardly along the inner periphery of the opened tube portion 10g. This sort of movement of the particles upwardly along the inner periphery of the opened tube portion 16g amounts to a movement of the particles upwardly along the outer peripheral portion of the fluid bed of particles 20 and a type of recirculation within the bed 20 such that those particles in the middle of the bed 20 will tend to drop down and replace thosebeing carried generally upward along the inner periphery of the tube 10g. In this way, fresh particles are constantly brought into contact with the inner periphery of the expanded tube 10g and this is advantageous.

The manner in which the particles in the bed effect removal of water or similar traces of liquid on the inner periphery of the expanded tube 10g is important at least to the extent that such particles do not lose their solid phase condition. Thus a collection of calcium chloride particles might not be desirable for any prolonged operation because such particles tend to collect so much water that they ultimately are converted to a concentrated liquid solution. On the other hand, while the calcium chloride particles were in solid condition they might be very effective in removing traces of moisture because of their extremely great attraction to such traces of moisture.

Preferred type of particles for this purpose are waterlacking or relatively dry fibers, water-lacking or com paratively dry nylon particles (sometimes referred to in the art as fused or dehydrated nylon), or many other similar particles which are relatively lightweight in character but which are generally not capable of being caused to adhere to the inner periphery of the moving plastic sleeve 10g simply by virtue of the traces of moisture or other liquid thereon to the extent that they would be carried all the way to the second nip N-2. A commercially available product usable in this procedure is referred to as sintered nylon. As previously mentioned, a much less expensive material also usable in the instant method and apparatus would be dried or water-lacking cellulose in any of its various forms including typical paper pulp fibers which have been dried. Most of these solids which have just been described as particulate materials are not necessarily round but they do pick up the liquid (water) traces by a type of capillary action so that they do not lose their solid state condition during their function.

It will also be appreciated that the fine particulate material used is chemically and physically essentially inert with respect to the solid plastic tube 10g, with and without any water or other liquid that it may pick up. In general, it has already been indicated that it is usually preferably that it absorbs or picks up water by capillary action or some other type of phenomenon that does not alter its physical state in the solid form. Its weight may be altered, of course, and this is ordinarily not helpful. In fact, if the material is too light the overall bed may be advantageously supplemented by the addition of metal shot or some other matreial that would serve to give added weight to the bed and thus assist in defining the desired configuration of the opened plastic tube 10g. In general, any type of solid particulate material that is so light or is so arranged that it would tend to ride along with the inner periphery of the plastic tube 10g clear to the second nip N-2 would not be desirable because the tendency to clog this nip should be avoided and, therefore, it is preferable to maintain the solid fluid bed at a level spaced from the second nip N-2. Most conveniently, this is done simply by positioning the second nip N-2 substantially above the level L of the bed 20 and using solid particulate material of weight at least significantly greater than that merely of the air or other gas thereabove so that it will 'not tend to ride all the way up to the nip N2, even though it will tend to be more or less continuously moved at its outer periphery to afford the desired circulation within the fluid body of the bed 20 itself. The bed 20 is made up of solid particles but it is referred to as fluid in character, much in the manner in which the skilled workers in the art refer to what is known as fluid bed drying, when gases are passed through moist solid particles to vaporize and remove the moisture while fluidizing the bed of particles. There is no real confusion in thus referring to what has already been described as solid particles as being part of a fluid bed 20, at least insofar as the skilled worker in the art is concerned. In respect to the fluidized or fluidizable character of the bed 20, however, it will be appreciated that there is a certain amount of desirability in haying this bed formed of particles which have at least a limited amount of adherence to the inner periphery of the expanded plastic tube 10g while they are carrying out their essential function of collecting the traces of liquid thereon so that the recirculation at the periphery of the particle bed 20 will be carried out for the most advantageous operation of the instant invention. It will be appreciated that this type of recirculation within the fluid bed 20 and/ or a type of recirculation at the periphery thereof is not absolutely essential if the solid particles will pass the liquid traces which they pick up from the inner periphery of the tube 10g among each other and thus effectively present fresh liquid-starved or water-starved solid bodies to the inner periphery continuously within the bed 20 so that the essential function thereof is carried out. And, again, in this respect it should be mentioned that all of the particulate bodies in such bed 20 need not have the same or identical characteristics. For example, some metal shot particles may be included therein and these particles will probably not be able to pick up very much water at any given moment (although they would not be expected to be totally incapable of picking up water), whereas they would preferably be mixed with highly liquid-starved or water-starved particles such as the previously mentioned sintered nylon and/ or water-starved cellulose fibers or similar types of particles. Preferably, however, the particles themselves do have the function in the bed 20 of a fluid bed in that they tend to recirculate by moving upwardly about the periphery of the bed 20 so that fresh particles will be continuously contacting the fresh areas of inner tube periphery brought into contact with the underside of the bed 29 leaving the nip N-1. Also, preferably these particles have a weight greater than not only that of the air or ambient atmosphere above the level L within the expanded tube 10g but also they have a weight which is sufficient to function in combination with any relaxation in the tension of the plastic tube between the nips N-1 and N-Z such that they are easily capable of overcoming any ambient outside fluid pressures which might tend to or attempt to collapse the tube 10g between these nips N-l and N-Z. Actually, the positioning of the nips N-l and N-2 may readily be such that expansion in the region 19g takes lace inherently merely by virtue of the relaxation of the tension and the particles in the particle bed 20 would thus have little or no functional weight, but even then they could not be of such character as to create a vacuum or a negative pressure diiferential'between the outside and inside of the tube portion 10g, which is ordinarily impossible in the case of any solid material. Going to the other extreme, the particles in the bed20 should not have such a great weight that they would actually generate forces against the inner periphery of the expanded plastic tube 10g that would exceed the modulus of elasticity or that would cause rupture thereof.

In the ordinary operation of the instant device, the fluid bed 20 will operate for a subtantial period of time continuously recirculating and continuously removing the relatively minute traces of liquid carried by the inner periphery of the plastic tube in the region 10g, but ultimately these particles may reach a stage where they have acquired too much moisture and/ or too much liquid from the inner periphery of the plastic tube10 and then it becomes desirable to replace the same with newer fresh liquid-starved or water-starved particles. This could take place every twenty-four hours, every week or even every month depending upon the amount of liquid actually carried by the plastic tube 12 on its inner periphery into the bed 20. On the other hand the replacement of the bed 20 with fresh material does not constitute a change or consumption of the actual fluid bed itself but merely an alteration thereof and the fluid bed 20 is a functioning part of the overall drying apparatus. The material consumed is the'liquid on the inner periphery of the plmtic sleeve 10. The replacement of particles partially or completely in the fluid bed 20 can take place quite readily simply by severing the plastic tube in the region 10g above the level L and permitting the top portion of the plastic tube to pass on into the subsequent conversion system while the festoon system 11 takes up the slack temporarily without any real reduction in speed of movement of the collapsed plastic tube 10. At this stage it will be appreciated that the solid fluidized bed of particles 20 can ordinarily not be completely removed or cleaned from the position here shown and can only be partially replaced by fresh particles, but this can be done very rapidly and in the course of normal operation and then the rising portion of the tube in the region 10g can readily be fed upwardly (or in any other direction which might be required) past the guiding boards 16 and 17 and into the second nip N-Z so that the overall drying operation may continue for whatever the usual period of time may be between the operational changes during which the particulate bed 20 is partially replaced by fresh liquid-starved particles. Those skilled in the are will readily recognize that this phase of the operation is not particularly complicated and it may be that some of the plastic tube would have to be fed off in a different direction for a brief moment while this change is taking place in the particulate bed 20 but there would be only a very nominal amount of plastic tube so expended and the changes in the fluid bed 20 could be caused to take take place very rapidly. Also, it will be appreciated by those skilled in the art that during conversion it is necessary often to cause breaks in the plastic tube in order to change from one converter system to another, so there can easily be arranged a timing in this situation such that there is no waste whatsoever of plastic tube. All of such operations are well within the skill of the art, once the instant disclosure has been explained to the skilled worker and need not be described in further detail herein.

To reiterate to some extent, it will be appreciated that one of the aspects of the instant invention involves a method of removing traces of liquid carried on the interior periphery of a substantially flattened tubular solid thin flexible elastic sheet material in which such liquid is substantially insoluble, which comprises driving said flattened sheet material longitudinally of its tubular axis by longitudinally spaced opposed pairs of co-moving surfaces engaging and completely flattening such tubular material along longitudinally spaced generally transversely aligned generally upper and lower narrow regions of engagement, driving such tubular material via driving engagement at such longitudinally spaced regions at relative driving speeds producing longitudinal tension in said sheet therebetween that is substantially beneath the modulus of elasticity of and rupturing force on the sheet, and maintaining a bed of solid fine particulate material spaced beneath the aforesaid upper region and entrapped against downward longitudinal movement within the tubular sheet by said lower region, said bed of particles engaging the interior of the longitudinally moving tubular sheet and applying downward and transversely outward forces to the interior of the sheet for the longitudinal height of such bed to subject the sheet to greater tension than that applied by said longitudinally spaced driving engagement but still substantially below said sheet modulus of elasticity and rupturing forces to bulge said tube outwardly immediately above said lower region by direct engagement between the sheet surface inner periphery and an outer peripheral layer of particles in the bed which layer of particles is continuously being moved upwardly and recycled back into the upper portion of the bed while being replaced continuously by particles from the lower portion of the bed reforming lower outer peripheral layers of such bed for continuous particle recycle and contact with the moving sheet inner periphery, said particles being non-tacky and substantially non-adherent to such inner sheet peripheral surface but being highly receptive of such liquid with the discrete individual bodies of such particles while retaining the generally particulate and mobile character of such fine particles affording the aforesaid continuous particle layer recycle and contact of fresh particles with the inner periphery of said tube.

It will be understood that modifications and variations may be effected without departing from the spirit and scope of the novel concepts of the present invention.

I claim as my invention:

1. A method of removing traces of liquid carried on the interior periphery of a substantially flattened tubular solid thin flexible elastic sheet material in which such liquid is substantially insoluble, which comprises driving said flattened sheet material longitudinally of its tubular axis by longitudinally spaced opposed pairs of comoving surfaces engaging and completely flattening such tubular material along longitudinally spaced generally transversely aligned generally upper and lower narrow regions of engagement, driving such tubuar material via driving engagement at such longitudinally spaced regions at relative driving speeds producing longitudinal tension in said sheet therebetween that is substantially beneath the modulus of elasticity and rupturing force on the sheet, and maintaining a bed of solid fine particulate material selected from the group consisting of sintered nyion, dehydrated cellulose, dehydrated nylon and mixtures thereof in combination with a predetermined portion of metal shot spaced beneath the aforesaid upper region and entrapped against downward longitudinal movement within the tubular sheet by said lower region, said bed of particles engaging the interior of the longitudinally moving tubular sheet and applying downward and transversely outward forces to the interior of the sheet for the longitudinal height of such bed to subject the sheet to greater tension than that applied by said longitudinally spaced driving engagement but still substantially below said sheet modulus of elasticity and rupturing forces to bulge said tube outwardly immediately above said lower region by direct engagement between the sheet surface inner periphery and an outer peripheral layer of particles in the bed, which layer of particles is continuously being moved upwardly and recycled back into the upper portion of the bed while being replaced continuously by particles from the lower portion of the bed reforming lower outer peripheral layers of such bed for continuous particle recycle and contact with the moving sheet inner periphery.

References Cited UNITED STATES PATENTS 2,476,140 7/1949 Francis 264- 3,214,327 10/1965 Wicker et al 34-95 X 3,275,549 9/1966 Crabb et al 349 X 3,275,723 9/1966 Cappuccio 264-210 X FREDERICK L. MATTESON, JR., Primary Examiner. D. A. TAMBURRO, J. J. CAMBY, Assistant Examiners.

Claims (1)

1. A METHOD OF REMOVING TRACES OF LIQUID CARRIED ON THE INTERIOR PERIPHERY OF A SUBSTANTIALLY FLATTENED TUBULAR SOLID THIN FLEXIBLE ELASTIC SHEET MATERIAL IN WHICH SUCH LIQUID IS SUBSTANTIALLY INSOLUBLE, WHICH COMPRISES DRIVING SAID FLATTENED SHEET MATERIAL LONGITUDINALLY OF ITS TUBULAR AXIS BY LONGITUDINALLY SPACED OPPOSED PAIRS OF COMOVING SURFACES ENGAGING AND COMPLETELY FLATTENING SUCH TUBULAR MATERIAL ALONG LONGITUDINALLY SPACED GENERALLY TRANSVERSELY ALIGNED GENERALLY UPPER AND LOWER NARROW REGIONS OF ENAGEMENT, DRIVING SUCH TUBULAR MATERIAL VIA DRIVING ENGAGEMENT AT SUCH LONGITUDINALLY SPACED REGIONS AT RELATIVE DRIVING SPEEDS PRODUCING LONGITUDINAL TENSION IN SAID SHEET THEREBETWEEN THAT IS SUBSTANTIALLY BENEATH THE MODULUS OF ELASTICITY AND RUPTURING FORCE ON THE SHEET, AND MAINTAINING A BED OF SOLID FINE PARTICULATE MATERIAL SELECTED FROM THE GROUP CONSISTING OF SINTERED NULON, DEHYDRATED CELLULOSE, DEHYDRATED NYLON AND MIXTURES THEREOF IN COMBINATION WITH A PREDETERMINED PORTION METAL SHOT SPACED BENEATH THE AFORESAID UPPER REGION AND ENTRAPPED AGAINST DOWNWARD LONGITUDINAL

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