US3585015A - Method of and apparatus for producing filaments from vitreous materials - Google Patents

Abstract

IN THE PRODUCTION OF FILAMENTS FROM VITREOUS THERMOPLASTIC MATERIAL THREADS OF THE MATERIAL IN LIQUID FROM ARE EXUDED ONTO THE THE SURFACE OF A ROTATING DRAWING DRUM AT A FIRST LOCATION AND ARE STRIPPED OFF THE SURFACE AT A DOWNSTREAM SECOND LOCATION. A SIZING SUBSTANCE FOR THE FILAMENTS IS APPLIED ONTO THE SURFACE OF THE DRUM INTERMEDIATE THESE TWO LOCATION SO AS TO BE TRANSFERRED ONTO THE FILAMENTS WHEN THE SAME CONTACT THE DRUM SURFACE.

Description

June 15, 1971 H. HOHLFELD ETAL METHOD OF AND APPARATUS FOR PRODUCING FILAMENTS FROM VITREOUS MATERIALS Filed Nov. 19, 1968 INVEN'I'ORS N 49 H0516 may 4mm Mammy mm/ (My fi thy-9747 United States Patent 015cc 3,585,015 METHOD OF AND APPARATUS FOR PRODUCING FILAMEN TS FROM VITREOUS MATERIALS Harald Hohlfeld, Wertheim (Main), and Gunter Wiegand,

Hasloch, Lower Franconia, Germany, assignors to Werner Hugo Wilhelm Schuller, Munich- Grunewald,

Germany Filed Nov. 19, 1968, Ser. No. 777,095 Claims priority, application Germany, Nov. 23, 1967, P 15 96 468.8 Int. Cl. C03c 25/02 U.S. Cl. 65-3 16 Claims ABSTRACT OF THE DISCLOSURE In the production of filaments from vitreous thermoplastic material threads of the material in liquid form are exuded onto the surface of a rotating drawing drum at a first location and are stripped ofl? the surface at a downstream second location. A sizing substance for the filaments is applied onto the surface of the drum intermediate these two locations so as to be transferred onto the filaments when the same contact the drum surface.

BACKGROUND OF THE INVENTION The present invention relates to the manufacture of filaments consisting of vitreous material.

More particularly, the invention relates to a method of producing filaments from vitreous thermoplastic materials, and to an apparatus for carrying out the method.

Apparatus known for this purpose includes a rotary drawing drum to which filaments are applied so as to the drawn thereby, and the drawn filaments are then moved away from the rotary drawing drum before passing through a complete revolution about the drum and are converted into fibers which are then used for further processing steps. The fibers are separated from the drum by a wiper or doctor blade which extends axially along the drum and serves to strip the filaments off the surface thereof.

Application of the filaments onto the drum surface is accomplished by exuding threads of the vitreous material, namely glass or the like, which is contained in a suitable receptacle in plastic condition, and these threads are then brought into contact with the surface of the rotating drawing drum.

Apparatus of this type is for instance disclosed in U.S. Pat. No. 3,330,008 in the name of Werner Hugo Wilhelm Schuller, to which reference may be had for a more complete description of the apparatus in question.

Prior to being stripped off the rotating drawing drum the filaments of vitreous material, that is the original threads which have contacted the drum surface and have thereon solidified into filaments, must be subjected to sizing, that is they are coated with a suitable material usually in liquid form. The purpose of this sizing operation is a dual one, namely on the one hand it is necessary to make the filaments readily flexible and on the other hand to assure that the filaments will adhere to the surface of the drum which latter rotates at very high speed. The latter purpose is of particular importance, especially in view of the fact that in an attempt to increase the output of known machines of this type the speed of drum rotation is constantly being increased. Evidently, a drum rotating at very high speed will entrain the ambient fluid, that is the air, which will form a boundary layer sweeping around and along with the surface of the rotating drum. The effect of this boundary layer is to lift the filaments off the drum surface before they can reach the point where they are to be stripped. If this occurs, and if the filaments are completely lifted away from the drum surface, then 3,585,015 Registered June 15,, 1971 they will become snarled and the machine must be stopped, the snarled portions removed and discarded, and the operation be restarted. If, on the other hand, the filaments are only partially lifted off the drum surface but still move along with the rotating drum, then a condition occurs which is known as fluttering and which is highly undesirable because it interferes with proper operation of the apparatus.

conventionally the sizing material, hereafter identified as sizing and understood as usually being in liquid form, is applied to the filaments upstream of their point of initial contact with the drum surface. In other words, the sizing material is applied to the exuded filaments intermediate their point of initial contact with the drum and their point of origination, for instance the orifices in the raw-material receptacle from which the filaments are exuded. This is usually accomplished by means of a sizing cloth which broadly speaking may be any absorbent material arranged in form of a bar-shaped structure, cushion or the like, having a length corresponding to the axial length of the drum and so positioned that the exuded filaments must move over and in contact with the sizing cloth prior to contacting the surface of the rotating drum. The sizing cloth is saturated with the sizing liquid and may for instance be mounted on a bar, rod or the like which is constantly or periodically rotated, with replacement sizing liquid being constantly dripped onto or otherwise supplied to the sizing cloth.

In order to properly coat the filaments with the sizing substance it is necessary that they engage the sizing cloth, which term as used hereafter is to be broadly construed in the context outlined above, with a certain tension. This is accomplished by so positioning the sizing cloth that it is located outside the tangent between the point of filament origination and the point of initial contact of the filament with the drum surface. Thus, intermediate these two points, the filament must undergo a bend or kink which should be as small as possible but heretofore has been impossible to avoid completely because only in this manner was it feasible to obtain the necessary tension of filaments running over the sizing cloth.

Generally speaking, this approach has been found feasible in the industry although the requisite tension and the kink produced in each filaments at times result in breakage of the filaments. Nevertheless, this has heretofore been accepted. It is practical, however, only if the quantity of filaments which are simultaneously exuded and drawn off by a single drum is strictly limited. Such drums conventionally have an axial length of 1000 mm. and tests have shown that the optimum number of filaments which can be simultaneously drawn by such a drum, utilizing the conventional sizing-cloth type of sizing-liquid application, is approximately 200 filaments. In the context of attempts to increase the productivity of the type of apparatus here in question, this limitation is highly uneconomical. The filaments have a diameter on the order 'of substantially mm. or less and it follows from this that two hundred such filaments if they abut one another will require an axial space of only approximately 2 mm. whereas the axial length of the drum used for drawing-off these two hundred filaments is 1000 mm.

It would appear, at first sight, as if the question of filament density, that is the spacing between adjacent filaments passing over the drum, could be solved simply by moving the filaments closer together. This is not correct, one of the contrary reasons being that when the machine is newly started or when, after a filament has broken, a new filament is being formed, the formation takes place as the initial exudation of a drop of the molten vitreous material from the receptacle containing the supply which drop, under the infiuenece of gravity, will descend downwardly and will draw behind it a tail which then becomes a filament. To be able to do this the drop must be allowed to obtain a certain weight and consequently a certain size and for this reason it is necessary that adjacent filaments, or points from which the material for the filaments is exuded, are not too close together because otherwise the descending drop would tear off adjacent filaments. Moreover, initially the descending drop with its tail will frequently undergo certain pendulum movements which, although relatively minor, would still bring it into contact with adjacent filaments and suffice to tear the same, if they were close enough.

Be that as it may, the filaments are arranged in a row adjacent one another and pass in this manner over the sizing cloth, becoming coated with the sizing liquid which is partially rubbed off onto the surface of the rotating drum when the filaments contact the same. The thus transferred sizing liquid then serves to prevent the following portions of the filaments from being lifted off the drum surface under the conditions outlined earlier. Because the filaments must pass over the sizing cloth or analogous element with a certain tension, as pointed out above, they will cut grooves into the sizing cloth. This is disadvantageous because, when the apparatus is restarted after shutdown or when a new filament is exuded after filament breakage, it may occur that any or all filaments will not enter into their respectively associated grooves in the sizing cloth, for instance because of pendulum movements of the initial drops, and they may thus come close to one another with the result that, if they move into contact, adjacent filaments will break and necessitate renewed shutdown of the machine.

This is clearly a disadvantage, as is the fact that inevitably all sizing cloths which have heretofore been used, regardless of the type of material which of course must always be absorbent, will inevitably harden over a period of time. This results in constant changes in the wear as well as the absorbent quality of the sizing cloth and this in turn results necessarily in constantly-varying transmittal of sizing liquid to the filaments and therefore to the drum surface. Tests have shown that a fluctuation of approximately 0.40.9% by weight of sizing liqud, as related to the weight of the fiber, is inevitable. Clearly, this inaccurate and varying application of the sizing liquid adversely affects the further processing of fibers made from the filaments as well as the spinning process to which such filaments or fibers may be subjected. If too little sizing liquid is applied, then the filaments will not adhere properly to the surface of the rotating drum with the result that filament withdrawal fluctuates so that the diameter of the filament is subjected to corresponding fluctuations and may be so decreased that filament breakage occurs. On the other hand, excess quantities of the sizing liquid are applied to the filaments, then the drum surface and the wiper blade will be frequently fouled. It is known in the art that very fine fractions of fibers will mix with the excess sizing liquid on the drum surface and form in effect an abrasive paste covering the drum surface and the doctor blade or wiper blade, and which must then be removed. This of course requires shut-down of the machine and since such machines are intended for continuous operation, this is not acceptable. It should be pointed out here that for instance for the manufacture of fibrous sliver it is desired that the proportion of sizing liquid to filament be constant at substantially 0.4%.

Another problem with the existing sizing-liquid applicators is the fact that they frequently must undergo repair or inspection and are located at a disadvantageous position. This position is dictated by the necessity for the filaments to be tensioned to some extent, in the manner and for the reasons set forth earlier. Because of this particular location, where any inspection or repair of the applicator, that is the sizing cloth, will necessarily interfere with the movement of the filaments, any such work to be carried out will evidently result in necessary shut-down of the entire machine.

For all of these reasons the industry has long sought an improvement in the application of sizing liquid to the filaments and the drum surface. Heretofore, however, no improvement of sufficient magnitude has become known.

It is, accordingly, an object of the present invention to provide an improved method for applying the sizing substance, usually a sizing liquid, to the filaments and to the drum surface.

An additional object of the invention is to provide an apparatus for carrying out the method.

This apparatus is to be very simple in its construction, to assure reliable application of constant quantities of sizing substance, and to be readily accessible for repair, servicing and inspection at all times and without interference with the continued operation of the machine.

SUMMARY OF THE INVENTION In accordance with one feature of my invention I provide a method of producing filaments from vitreous thermoplastic material wherein the threads of liquid material contact the surface of a rotating drawing drum in known manner at a first location and are carried along by the drawing drum in downstream direction while undergoing solidification. Thereafter, they are stripped off in form of filaments at a second location upstream of the first location.

My invention provides for the application of a sizing substance for the filaments directly onto the surface of the rotating drum so that a requisite quantity of the sizing substance undergoes transfer to the filaments moving over the surface simply as a result of contact with these filaments.

This is a radical departure from anything that is being used in the art, and from any approach that is known to me at this time. The novel method of my invention, and the apparatus for carrying out this method, permit me to apply a thin film of sizing substance directly onto the drum surface, and this film can be exactly dosed and controlled. I wish to point out that this approach of applying the sizing substance indirectly to the filaments by letting it be transferred through contact of the filaments with the coated surface of the drum, has heretofore been considered impossible.

It is a particular advantage of my novel invention that it makes it possible to apply a consistently exactly controlled quantity of sizing substance to the drum surface, and thus enables me to provide a constant percentage of sizing substance, for example 0.2% to approximately 0.5% as related to the weight of the filaments, onto the filaments, this percentage being controllable at the will of the operator.

I may, in accordance with my invention, provide a sizing cloth which is maintained saturated with the sizing liquid and is reciprocated axially over the drum surface at a location where it will not interfere with the filaments. Again, a suitable cylindrical roller, consisting for example of rubber of synthetic plastic material, may be mounted at such a location that it will not interfere with the filaments and in such a manner that it will contact the drum surface extending axially of the drum and being rotatable about an axis paralleling that of the drum. Then the sizing substance can be applied onto the roller and transferred from there onto the surface of the drum. This method of applying the sizing substance by direct contact is within the scope of my invention, but requires relatively large quantities of sizing substance and does not preclude the possibility of fouling of the applicator roller by fiber fragments which may adhere to the drum surface. Of course, this comment applies also to the use of a cloth which is reciprocated in contact with the drum surface in axial direction thereof. Also, it is frequently difficult to prevent such a cloth or roller from removing sizing substance 5 from the drum surface and to assure that it will only apply the substance to the surface.

I therefore prefer to apply the sizing substance without directly contacting the drum surface with the applying instrumentality. This can be carried out by dripping or spraying the sizing substance from a certain distance onto the drum surface.

However, in this latter case the boundary layer of ambient air which is entrained by the high speed of rotation of the drum which latter withdraws the filaments at a speed of approximately 3000 m./min., proves an obstacle. If the boundary layer reaches a certain thickness it will prevent penetration of the droplets of sizing substance, whether dripped or sprayed, and contact of these droplets with the drum surface. This can be overcome to some extent by avoiding under such circumstances the use of a drip approach entirely and spraying the liquid onto the surface of the rotating drum with a certain pressure. It is, however, possible that even this will not suffice to effect penetration of the droplets through the boundary layer, depending upon the thickness and flow intensity of the latter which is determined not only by the rotational speed of the drum but also to some extent by the surface characteristics of the drum. This disadvantage may be overcome by damming the boundary layer upstream of the location where the sizing liquid is to be applied onto the drum surface, so that downstream of the point of damming, the term downstream referring to the direction of rotation of the drum and the direction of movement of the boundary layer, a suction and movement of air in the direction inwardly towards the drum surface will be created. Thus, the inwardly moving air will actually aid in depositing the droplets of sizing liquid on the drum surface.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The single figure illustrates an apparatus for carrying out the invention in a very simplified and diagrammatic axial elevation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing the drawing drum is identified with ref erence numeral 1 and is rotated in the direction of the arrow A about the shaft or axis 6. The drum may have the conventional length of 100 mm. and a suitable diameter known to those skilled in the art. A plurality of rows of filaments of vitreous thermoplastic material are identified respectively with reference numerals 2a, 2b, and 20. Each of these rows, namely either the row 20, the row 212 or the row 2c may consist of one hundred or more parallel filaments which are spaced from one another in the direction of the axis of the drum 1. Evidently, each of the lines designated with reference numeral 2a, 211 or 20 indicates one such row and it is to be understood that each such line represents one hundred or more individual filaments. How the filaments are exuded is immaterial here but for a more detailed description of how the liquid vitreous material is supplied, reference may be had to the aforementioned US. Pat. No. 3,330,008.

The filaments of the rows 2a, 2b and 2c initially are created by the formation of drops of liquid vitreous material exuded through nozzles or the like in a receptacle containing the supply of raw material. Under the influence of gravity these drops draw after them ever-lengthening tails which become the individual filaments and which are deflected by a suitable guide bafile 3 of known construction towards and into engagement with the surface of the rotating drum 1. On contact with the surface of the rotating drum the filaments are drawn off and carried around by the drum in the direction of the arrow A, new material being constantly drown down from the supply receptacle. On reaching the Wiper or doctor blade 4 shown in the drawing, the now-solidified filaments are stripped off the drum surface by the leading or stripping edge 7 of the blade 4, and at the same time the filaments are converted into fibers by contact with the blade 4. These fibers are guided away from the drum 1 by the guide baflle 5 for further processing.

Rotation of the drum 1 about the axis 6 results in the formation of a boundary layer consisting of entrained ambient gaseous fluid, e.g. air, and this boundary layer sweeps along with the surface of the drum 1 in the direction identified by the dual sets of arrows G. This boundary layer will at least to some extent be dammed by the blade 4, namely upstream thereof with respect to the rotation of the drum 1, and is deflected by the deflecting baffle 5, thus serving to transport away the fibers resulting from conversion of the filaments lifted off the surface of the drum 1 by the blade 4. In fact, the thus-dammed and diverted boundary layer may serve to deposit these fibers on a conveyor belt, a spinning channel for making a fibrous silver, or to another location for another purpose. A part of the boundary layer, signified by the arrow G, will however pass beyond the blade 4 underneath the stripping edge 7 thereof. Downstream of the blade 4 the boundary layer, here identified with the arrow G, will of course be much diminished in thickness and speed of movement, until it builds up again to the previous thickness and speed identified by the arrows G. Therefore, in the region of the boundary layer G droplets of sizing liquid dripped or sprayed in the direction of the surface of the drum 1 will be able to penetrate the boundary layer. Accordingly, I provide a suitable applicator means which is generally identified with reference numeral 9 and which may simply be in form of a receptacle containing the sizing liquid and extending over the entire axial length of the drum 1, or a shorter receptacle which may be mounted in suitable manner for axial reciprocation along the drum 1. The sizing liquid may then be allowed to drip from this receptacle -9 onto the surface of the drum 1, as indicated with reference numeral 10. Evidently, if the receptacle 9 extends over the entire axial length of the drum 1 in form of a trough or the like, it will be provided with a plurality of apertures through which the liquid may drip, whereas if the receptacle is shorter than the axial length of the drum 1, one or a few such apertures may be sufficient. In the latter case use may be made of a known chain drive or analogous means well known in the art for effecting the axial reciprocation of the receptacle 9 with respect to the drum 1. Of course, instead of dripping the sizing liquid from the receptacle 9, it may also be sprayed and how this can be accomplished is well known in the art and forms no part of the present invention.

Circumstances may, however, obtain wherein even the diminished boundary layer G will prevent dripped or sprayed sizing liquid from reaching the surface of the rotating drum 1. This may for instance be because the drum 1 is required to rotate at particularly high speeds and/or because the particular surface characteristics of the drum are conducive to the formation of a particularly strong boundary layer. Another possibility is that for structural reasons it may be necessary to position the receptacle 9 or the analogous applicator means at such a location with respect to the drum 1 that the boundary layer G will already have built up 'by the time it reaches the location at which the applicator means dispenses the sizing liquid. In this case I provide separate bafiie means for again damming the boundary layer, here illustrated as located downstream of the blade 4. In the illustrated embodiment I accomplish this by providing a damming baflle 8 which dams the boundary layer G, as indicated by the upwardly deflected arrow, with the result that at the downstream side of the baflle 8 an air current develops which is identified by the arrows S and which sweeps inwardly in the direction towards the surface of the rotating drum 1. This air current produces a suction effect and will, if sizing liquid is introduced into it in droplet form, carry such droplets towards the surface of the drum 1 and deposit them thereon in form of a thin film. It should be noted that in this case it will ordinarily suffice to let the liquid drip from the receptacle 9 without pressure or under very slight pressure. Spraying will not ordinarily be necessary although resort to this method may also be had.

Tests have shown that if I deposit only approximately 3 grams of sizing liquid per hour upon the surface of the rotating drum 1, the simultaneous and proper drawingoff of more than 350 filaments with a single 1000 mm. long drum is assured. This is almost double the number of filaments which could heretofore be withdrawn under optimum conditions. Moreover, the film of sizing liquid on the surface of the drum is so thin under this circumstance that fouling of the drum and the blade 4 is virtually nonexistent.

I may use as the sizing liquid a simple organic or inorganic oil having good sliding and adhesive characteristics. It is not necessary to provide such oil with additives, for instance additives which impart antistatic characteristics to it.

If I resort to the use of a separate baflle 8 it may be advantageous to mount the batfle 8 either movable towards and away from the surface of the drum 1 in the direction indicated by the arrows BC, or tangentially thereof an indicated by the arrows DE by means represented by 13 and 14 respectively. Mounting means for such purposes are well known in the art and need not be described. By making the baflle movable in this manner I make it possible to vary the suction indicated by the arrows S in dependence upon the rotation of the drum 1, and to regulate it according to whatever requirements may exist. The drawing shows that there is a slight space between the surface of the drum 1 and the lower edge of the baflie 8. This space may be very minute and may be in some cases on the order of approximately mm. This may cause a problem if agglomerations of fibers or other contaminants which have adhered to the edge 7 of the blade 4 and suddenly are torn loose, are carried along against the bafile 8 and then become wedged into the gap between the surface of the drum 1 and the lower edge of the baflle 8. To avoid any problem resulting from this I may make the baffle 8 pivotable about an axis 12 which parallels the axis 6, as illustrated in the drawing. Alternately, only the lower part of the baffle may be so pivotable about the axis 12, and then, of course, the baffle will be of two-part construction. In any case, pressure against the lower part of the baffle 8 by such agglomera tions of fibers and other contaminants will then cause the baffle to turn in clockwise direction about the pivot 12 until the gap between the surface of the drum 1 and the lower edge of the baflie 8 is sufficiently large to permit passage of the obstruction which is carried away. A restoring spring may be provided for restoring the baflle 8 to its normal operating position as illustrated in the drawing.

The provision of the baffle 8 is particularly advantageous because it permits the application of sizing liquid onto the surface of the drum 1 at any desired location, regardless of the thickness and speed of the boundary layer. The term desired or suitable location of course refers to a location, as seen with reference to the circumference of the rotating drum 1, which will not interfere with the movements of the filaments 2a, 2b and 20, which is readily accessible and observable so that observation and/or repair and servicing of the applicator means are assured. A further advantage of the use of the baffle 8 for diminishing the boundary layer, as opposed to the diminished boundary layer downstream of the blade 4, resides in the fact that the baflie 8 can be made movable in the direction of the arrows BC and/or the arrows DE so that the suction created downstream of the baflle 8 may be adjusted as to its intensity by such movement. In fact, the battle 8 has a further advantage, namely the fact that under certain circumstances the damrning of the boundary layer at the upstream side of the baffle 8, and the consequent deflection of the boundary layer, may be utilized for purposes of stripping the filaments off the drum surface, thereby making it possible to eliminate the blade 4 and the deflector baflle 5.

Tests undertaken with an apparatus according to my novel invention have shown that the transfer of sizing liquid from the film applied onto the surface of the drum 1 to the filaments is entirely adequate for the purposes at hand, but at the same time is not as high as the transfer which takes place when these filaments move over a conventional sizing cloth. This is particularly advantageous if the fibers into which the filaments are transformed on encountering the blade 4 are to be used for making a fibrous sliver because the lower quantity of sizing liquid adhering to these fibers reduces the weight of the fibers and assures that the latter will fly more freely when deflected by the deflecting baflie 5 and carried along by the deflected boundary layer G.

Finally, it should be pointed out that an additional advantage of my novel invention is the fact that each filament drawn by the rotating drum 1 will have a larger freedom of lateral movement on the surface of the drum 1 than heretofore possible, simply because it is not prevented from such movement by running in the grooves which are inevitably cut into the sizing cloths. Tests conducted in this respect have shown that the total lateral movement of any one filament may be as high as 30 mm. without any danger of contact with an adjacent filament and consequent tearing thereof. Evidently, this relatively great freedom of lateral movement assures that the film of sizing liquid on the surface of the drum 1 will be used up substantially uniformly even on those portions of the surface of the drum 1 about which a filament is not directly convoluted. This decreases the quantity of sizing liquid required.

We claim:

1. In a method of producing filaments from vitreous thermoplastic material, including contacting the threads of the vitreous thermoplastic material with the surface of a rotating drawing drum at a first location and carrying the threads in downstream direction on the drum to undergo solidification and thereafter stripping the threads off the drum at a second location downstream of said first location so as to form between said first and second locations an exposed drum surface portion free of filaments, the improvement consisting in applying a sizing substance for said filaments at a third location onto said exposed drum surface portion free of filaments for contact-transfer of such substance from said exposed drum surface portion to the respective filaments.

2. In a method as defined in claim 1, wherein said sizing substance is applied onto said surface at a third location intermediate said first and second locations.

3. In a method as defined in claim 2, rotation of said drum entraining a boundary layer of ambient gaseous fluid; further comprising partially damming said boundary laver upstream of said third location to thereby provide in the region of said third location a movement of gaseous fluid in direction toward the surface of said drum; and introducing the sizing substance in liquid form into the gaseous fluid at said third location for deposition onto said surface.

4. In a method as defined in claim 3, the step of introducing the sizing substance in liquid form comprising dripping the substance into the gaseous fluid at said third location.

5. In a method as defined in claim 3, the step of introducing the sizing substance in liquid form comprising spraying the substance into the gaseous fluid at said third location.

6. In an apparatus for manufacturing filaments from vitreous thermoplastic material, the combination comprising forming means for forming a plurality of threads of vitreous thermoplastic material; a rotary drawing drum for receiving said threads in plastic state at oneside and for drawing said threads while they undergo solidification into filaments and pass around said drum to another side thereof, said drum entraining during rotation thereof a boundary layer of ambient gaseous fluid which sweepsalong said surface in direction of rotation of the drum; stripping means for stripping the filaments off said drum at said other side; applicator means operative for applying to the surface of said drum downstream of said stripping means but upstream of said one side a sizing substance for contact-transfer of such substance from said surface to the threads; and bafile means upstream of said applicator means and downstream of said stripping means and being operative for damming said boundary layer upstream of said applicator means to thereby prevent interference of the boundary layer with deposition of the sizing substance onto said surface.

7. In an apparatus as defined in claim 6, said applicator means comprising spraying means for spraying said sizing substance onto said surface.

8. In an apparatus as defined in claim6, said sizing substance being in liquid form, and said applicator means comprising dispensing means arranged for dripping said substance onto said surface.

9. In an apparatus as defined in claim 6, said bafiie means being unitary with said stripping means.

10. In an apparatus as defined in claim 6, said baflie means being located downstream of said stripping means.

11. In an apparatus as defined in claim 6, said sizing substance being in liquid form and said applicator means being spaced from said surface and comprising discharge means operative for discharging the liquid sizing substance onto said surface.

12. In an apparatus as defined in claim 1 1, said baflle 10 means being mounted on an axis parallel to the axis of said drum.

13. In an apparatus as defined in claim 11, including mounting means comprising adjusting means mounting said bafiie means for movement towards and away from said surface so as to enable positioning of said baflle means at a desired distance from said surface and permit consequent selection of the degree of damming effect provided by said bafiie means.

14. In an apparatus as defined in claim 11, including mounting means comprising adjusting means mounting said baflle means for movement tangentially to said surface so as to enable positioning of said baflle means at a desired distance from said surface and permit consequent selection of the degree of damrning efi'ect provided by said baffie means.

15. In an apparatus as defined in claim 11, said drum rotating about a first axis and said baffle means having an edge portion proximal to said surface; and mounting means mounting said baffie means for movement about a second axis radially spaced from said surface and remote from said edge portion said second axis substantially paralleling said first axis so that said baffile means may be deflected about said axis in the presence of and in response to abutment with solid projecting contaminants on said surface.

16. In an apparatus as defined in claim 6, said sizing substance being a liquid, and said applicator means comprising dispenser means for the liquid reciprocable in axial direction of said drum for distribution of the liquid over the entire axial extent of said surface.

References Cited UNITED STATES PATENTS 2,132,016 1 0/1938 Du Bois 162-112 2,584,517 2/1952 Verreet --1UX 2,931,421 4/1960 Schuller 65-9 S. LEON BASHORE, Primary Examiner R. L. LINDSAY, In, Assistant Examiner U.S. C1. X.R.

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