US3294503A - Apparatus for producing fine continuous filaments - Google Patents

Description

Dec. 27, 1966 G. R. MACHLAN ETAL 3 5 APPARATUS FOR PRODUCING FINE CONTINUOUS FILAMENTS Filed April 1, 1965 5 Sheets-Sheet 1 650F615 R MACHL/I/V, CHARL 5 1, Mam/M5 &

HELL/W07 5L ASE/ INVENTORS Dec. 27, 1966 G. R. MACHLAN ETAL 3,294,503

APPARATUS FOR PRODUCING FINE CONTINUOUS FILAMENTS Filed April 1, 1963 5 Sheets-Sheet 2 HELLMUT 6145/9? INVENTORS A TTORNE VS 1966 e. R. MACHLAN ETAL $294,503

APPARATUS FOR PRODUCING FINE CONTINUOUS FILAMENTS 5 Sheets-Sheet 3 Filed April 1, 1963 GEO/P65 R MAO-MAN, CHARLES L. McK/N/m & HELLMUT 6LA5A INVENTORS United States Patent 3,294,503 APPARATUS lFtDR PRQDUQHNG FENE CQNTKNUUUS FELAMENTS George R. Maehian, Newark, and (Zharles L. McKinnis,

Granville, Uhio, and Helhnut I. Glaser, Anderson, S.C,,

assignors to Owens-Corning Fiberglas Qorporation, a

corporation of Delaware Filed Apr. 1, 1963, Ser. No. 269,510 5 flaims. (Cl. 651l) The present invention relates to fine continuous filaments formed of heat-softenable mineral material, such as glass, and to a method and apparatus for forming extremely fine filaments rendering the production of such filaments economical on a commercial scale.

Strands of continuous filaments formed of glass have been produced commercially and utilized in forming fabrics and such fabrics have the advantage of good strength characteristics and stability. Commercial strands of continuous filaments that have been produced commercially have been of sizes greater than an average filament diameter of twenty hundred thousandths of an inch. It has been found that while such filaments have high strength characteristics, greater flexibility of finer filaments is desirable in fine fabrics particularly as such fabrics must be capable of withstanding folding.

Fabrics heretofore made of yarns of glass filaments, while exhibiting good Wear characteristics, have not had good resistance to abrasion and exhibited poor fiexure characteristics. It has been found that by substantially reducing the size or diameter of the continuous filaments that the strands of these very fine filaments woven or fashioned into fabric provide a fabric having substantially higher tensile strength and improved folding, fiexure and abrasion resistant characteristics. They exhibit improved drape and a more softer luxurious hand or appearance with greatly increased resistance to wear and hence a much longer life.

While it has been possible to attentuate glass into extremely fine filaments, it has not heretofore been economical to produce extremely fine filaments on a commercial scale by reason of numerous difficulties in effecting start-up upon break-outs of one or more filaments and the tendency of the glass to flood across the space between adjacent glass streams.

The present invention embraces a method of forming and processing streams of heat-softened mineral material to form continuous extremely fine filaments collected in strand formation whereby the commercial production of yarns of extremely fine continuous filaments may be effected.

An object of the invention resides in a method of producing extremely fine filaments of glass by attenuation of streams of glass involving delivery orifices of special character and environment whereby the start-up time or time required to reinitiate attenuation after filament breakouts is greatly reduced over prior methods.

Another object of the invention resides in a method of flowing streams of heat-softened glass through orifices in a manner reducing the tendency of the glass to flood and facilitating the employment of a comparatively large number of stream feeding orifices whereby extremely fine continuous filaments are attenuated from the streams to form a strand comprising a large number of extremely fine filaments which may be produced economically and on a commercial scale.

Another object of the invention is the provision of an arrangement for heat-conditioning glass or other mineral material for the production of fine filaments from streams of the material wherein the pieces of material or batch are reduced to a fiowable state under conditions promoting a uniform throughput of the glass through the Patented Dec. 27, 1%66 delivery orifices with a minimum of temperature variation and thereby minimize break-outs and interruption of attenuation of the streams to filaments.

Another object of the invention is the provision of a method of heat-conditioning the glass in a glass melter region providing a comparatively long residence time for the glass in the heated environment sufiicient to promote the movement of the molten glass in laminar planes, the glass moving downwardly substantially uniformly through the feeder or bushing section to the delivery orifice or tip section whereby channeling of the glass or the tendency of the glass to migrate through adjacent laminae is substantially eliminated.

Another object of the invention is the provision of an arrangement for heat-conditioning glass or other filamentforming mineral material in a melter and feeder construction to attain a substantially uniform temperature glass to promote a uniform throughput with a minimum of temperature variation reduced to a tolerance fact-or satisfactory for the attenuation of fine filaments with a minimum of break-outs.

Another object of the invention is the provision of the method of processing glass or other filament-forming mineral material by metering the input of glass or filamentforming mineral rnaterial into a melter region in a manner whereby temperature variations set up by reason of the introduction of pieces of glass or batch into the melt are reduced to a minimum well Within a temperature tolerance satisfactory for the attenuation of extremely fine filaments.

Another object of the invention resides in the provision of stream feeder tips and their orientation on a feeder or bushing tip section whereby the time required to form a bead of molten glass at a tip and the time within which such bead drops from the initiation of its formation are reduced and thereby reducing the start-up time of filament attenuation, rendering the process commercially economical for the production of extremely fine continuous filaments.

Another object of the invention resides in the provision of a novel feeder tip and orifice construction for the delivery of molten glass wherein the tip face and other dimensional characteristics of the tip are proportioned to reduce the bead formation and bead drop time to a minimum and to reduce the lateral dimension of a head to enable positioning a plurality of tips in close relation with a minimum liability of flooding to enable the simultaneous attenuation of a comparatively large number of extremely .fine filaments gathered into a single strand and reducing the liability of break-outs to foster continuous attenuation.

Another object of the invention resides in the provision of a feeder having a large number of orificed tips having particular dimensional characteristics and the tips oriented in a manner and the molten glass maintained at a temperature which accelerates the formation of a bead in case of break-out of the filament formed from the stream and reducing the bead weight to promote a more rapid bead drop time to facilitate faster restarts of the winding operation in a minimum of time.

Further objects and advantages are within the scope of this invention such as relate to the arrangement, oper ation and function of the related elements of the structure, to various details of construction and to combinations of parts, elements per se, and to economies of manufacture and numerous other features as will be apparent from a consideration of the specification and drawing of a form of the invention, which may be preferred, in which:

FIGURE 1 is a semi-schematic elevational view of an arrangement embodying the invention and illustrating a method of processing and conditioning glass for attenuation of fine continuous filaments therefrom;

FIGURE 2 is a vertical sectional view of the glass heating and conditioning apparatus of the invention;

FIGURE 3 is a sectional view taken substantially on the line 3-3 of FIGURE 2;

FIGURE 4 is a bottom plan view of a portion of the tip section of a stream feeder, and

FIGURE 5 is an enlarged fragmentary detail sectional view illustrating the dimensional characteristics and orientation of the orificed tips on a stream feeder.

While the method and apparatus of the invention have particular utility in heat-conditioning and processing glass for forming extremely fine textile filaments, it is to be understood that the method and apparatus of the invention may be utilized for conditioning and processing other mineral materials.

Referring to the drawings in detail and initially to FIG- URE 1, a form of the apparatus of the invention is illustrated which is especially adaptable for the formation of extremely fine continuous filaments of glass for forming textile strands, threads or yarns. The arrangement is inclusive of a melter and feeder construction or unit for heat-conditioning glass which is flowed through orificed projections provided on the floor of the feeder tip section as fine streams which are attenuated into fine continuous filaments 12.

As shown in FIGURE 1, the continuous filaments 12 are attenuated by mechanical attenuation and, in the arrangement illustrated, are converged to form a multi-filament strand 14 through the medium of a gathering device or shoe 16, the strand 14 being wound upon a collector or collecting surface in the form of a tubular sleeve 18 mounted upon a mandrel 20 driven by suitable motive means (not shown) contained in a winding machine housing 22 of conventional construction. During winding of the strand 14 upon the collector 18, the strand is traversed lengthwise of the collector 18 to build up a strand package of superposed layers of the strand, a traverse means 24 being engaged with the strand and arranged to effect oscillation of the strand in order to effect a crossing of successive convolutions of strand 0n the collector to prevent adjacent convolutions of strand from adhering together. A lubricant, size or other coating material may be applied to the filaments by engaging them with a roll applicator 26 of conventional character.

The arrangement illustrated in FIGURE 1 is adapted to melt or heat-condition pieces of glass such as preformed glass marbles 29 introduced into the melter component of the unit 10 through chute means 30 from marble metering or feeding means associated with a marble supply.

The pieces of glass or marbles are metered by means dependent upon minute variations in the level of molten glass or material in the melting regoin. The melter and feeder unit 10 and the means for metering the delivery of marbles or pieces of glass into the unit and the supply hopper are supported by a frame structure 32.

As shown in FIGURE 1, a member 33 of the frame 32 supports a supply hopper 36 in the lower region of which is disposed a metering means in the form of a drum 41 mounted upon a shaft 42 driven by a motor 44 through suitable gearing 45 or other transmission mechanism. In

the embodiment illustrated, the drum 41 is provided with two rows of sockets or recesses 46 of a character to receive marbles of glass from the hopper 36 and, upon rotation of the drum, are metered or delivered through the feed chutes 30 into the melter region 60 of the unit 10.

The upper wall 50 of the unit 10 is provided with a tubular member 52 in which is disposed a probe rod or electrode 53 connected with a control means contained within a programmer, shown schematically at 56, arranged to regulate or control the operation of the motor 44 to deliver the marbles from the recesses in the drum through the chutes 30 into the melter. Electric power supply for the programmer 56 is indicated at L1 and L2.

Through the programmer 56, a circuit is established through the probe 53 to the motor 44 for effecting rotation of the marble feed drum 41 to substantially continuously feed glass marbles from the recesses 46 in the drum to the marble chutes 30,

The rate of rotation of the motor 44 and the feed drum 41 is controlled to slightly overfeed glass marbles into the melter 60, that is, at a rate slightly greater than the throughput of glass discharged as streams from the feeder when the level of glass is below or out of contact with the probe 53.

The overfeeding of glass into the melter raises the level of the glass to a point where contact is made between the probe 53 and the glass in the melter. When this occurs, the probe circuit, through the programmer 56 is arranged to reduce the speed of the motor 44 to feed the marbles or pieces of glass into the melter through the chutes 30 at a lesser rate than the rate of throughput of the glass by way of the streams and thereby reduce the level of the glass in the melter.

Thus the probe 53 establishes an overfeed of glass marbles to the melter 60 when the glass is out of contact with the probe. The probe 53 establishes an underfeed of marbles or glass into the melter when the glass contacts the probe. Through this level control arrangement, a substantially constant head of molten glass is maintained in the melter and feeder unit 10. The cover 50 is provided with a vent tube for venting gases or volatiles given off by the glass in the melter.

FIGURES 2 and 3 illustrate one form of melter-feeder unit or arrangement for melting and heat-conditioning glass from which extremely fine continuous filaments may be formed. The arrangement comprises a substantially rectangular melter region defined by side walls 62, a top cover plate 50, and end walls 64, the side and end walls being joined with the horizontal cover plate 50 by angularly arranged connecting portions 66 and 68. The cover plate 50 is fashioned with coupling bushings 51 which are in registration with the chutes 30.

The feeder section or region 70 is fashioned with side walls 72 which are joined with the side Walls of the melter section by angularly arranged connecting portions or plates 74, as shown in FIGURE 4. The end walls 64 are provided with extensions forming end walls of the narrower feeder section 70. A current conducting or heater screen 76, preferably formed of an alloy of platinum and rhodium in the shape of an inverted V, is disposed lengthwise between the melter region 60 and the feeder or conditioning region 70 as particularly shown in FIGURE 3 and is fashioned of suitable mesh to prevent the entrance of any unmelted fragments or pieces of glass entering the feeder section. The highest temperature in the melt is beneath and adjacent the heating screen 76, Thus the melting occurs in the chamber 60 and the temperature progressively increases to the region just beneath the screen 76. From this region downward, the temperature of the glass gradually decreases in a manner to promote movement in laminar planes to effectively refine and render the glass homogeneous for attenuation.

Welded to each end of the melter-feeder unit 10 are terminals which are connected by clamps 81 with suitable bus bars or current conductors 82 which are connected by conductors 83, shown in FIGURE 1, with a source of electric current L3, L4 through a control unit 58 which provides the media for melting the glass in the melter section and heat-conditioning the glass in the feeder or conditioning section to the desired viscosity to obtain a required throughput through the orifices in a tip section of the feeder.

The current supply circuit to the terminals 80 is of low voltage and high amperage and is regulated by conventional means in the control unit 58 for melting the glass and maintaining a proper temperature of the glass in the feeder section. Thermocouples (not shown) are disposed in various regions of the feeder and melter sections for indicating to an operator the temperature of the glass in the sections. The amount of electric current flow through the unit determines the rate of melting in the melter and the temperature of the glass in the feeder section and is controlled by conventional means in the control unit 58 connected with heat responsive devices (not shown) positioned in the unit 10. It should be noted that the melter section is of substantial depth and that the feeder section is narrower than the melter section and is of substantial depth in order to maintain a comparatively large amount of glass in the melter and feeder sections. By providing a substantial amount of glass in the unit It) a sumcient residence time is had for the glass in the melter and feeder to promote the heat-conditioning of the molten glass in laminar planes so that the molten glass in the feeder section at the region of the delivery orifices is of uniform temperature and substantially homogeneous throughout so that the same amount of throughput is had through each of the orificed tips. The dimensional and flow characteristics of the melter and feeder construction should be fashioned to provide for a residence time of about one and one-half hours or more for the economical production of fine filaments. The refractory 85 surround ing the melter 60 and conditioning region 70 should be comparatively thick to stabilize the temperatures to promote laminar flow. The conditioning region 70 should be relatively narrow in width in order to maintain temperature control at the central region as otherwise laminar flow will be impaired.

The receptacle providing the melter region and feeder region may be fashioned of metals or alloys capable of withstanding the intense heat of the molten glass or other mineral material, and alloys of platinum and rhodium have been found to be generally satisfactory for the purpose.

The floor of the feeder comprises a component or sec tion, usually referred to as a tip section, which is formed with depending hollow projections or tips providing passages or orifices through which flows streams of molten glass from the feeder. In the embodiment illustrated, the feeder or tip section 959 is of generally rectangular shape having a horizontal planar floor portion d2 with which are joined upwardly and outwardly converging walls or wall portions 94 terminating in flanges which are welded to outwardly extending flanges 98 formed on the side walls 72 of the feeder section '75.

The tip section $0 is preferably fashioned of an alloy of platinum and rhodium but may be fashioned of other suitable high temperature resistant metals or alloys. The tip section 9% is formed with a plurality of depending projections 1%, usually referred to as tips, each tip being formed with an orifice, channel or passage through which a stream of molten glass is delivered from the feeder.

The number of orifices and hence the number of streams of glass flowing from the feeder determine the number of fine filaments as a continuous filament is attenuated from each stream.

The projections 109 are arranged in transverse and lengthwise rows in the manner illustrated in FIGURE 4, the spacing of the rows and the character and dimensions of the projections and orifices or passages therein being major factors in the economical production of extremely fine continuous filaments. The geometry of the tip construction and the factors affecting the production of continuous filaments will be hereinafter described.

In order to promote flow from the tip section of streams of molten glass of uniform size and characteristics, the molten glass in the feeder section is maintained at a temperature above an attenuating range providing a more liquid glass to be delivered through the orifices. As a highly liquid glass is of too low viscosity for satisfactory attenuation, an arrangement is provided adjacent the delivery region of the streams from the projections or tips 1% to condition and stabilize the viscosity of the glass to facilitate attenuation.

As shown in FIGURES 1 through 4, there is disposed lengthwise of the tip section a tubular manifold 164 having inlet and outlet tubes 105 and 1% for connection with a heat-absorbing or heat transfer medium, such as Water circulated or flowing through the manifold. Welded or otherwise joined with the manifold in heat transferring relation therewith is a plurality of heat transferring fins or members 108.

In the embodiment illustrated, as particularly shown in FIGURE 5, a fin or member 1&8 is disposed between each transverse row of projections or tips to absorb or withdraw heat from the streams of glass to increase the viscosity of the glass of the streams to a satisfactory attenuating temperature or condition. While, in the embodiment illustrated, a fin or member 100 is provided between each transverse row of projections, it is to be understood that, if desired, one fin may extend between alternate rows, but in such construction the projections between adjacent fins are disposed in closer relation.

FIGURE 5 illustrates, on a greatly enlarged scale, a form of projection or tip construction 100 typical of a character suitable for flowing streams of glass for attenuation to extremely fine filaments. Filaments formed by the method or process of the invention are in a size range under eighteen hundred thousandths of an inch in diameter. For example, strands formed of continuous filaments having an average diameter of fourteen hundred thousandths of an inch have been produced, and tests have been successful in producing filaments of less than eight hundred thousandths of an inch through the use of the method of the invention.

There are several factors which are found to be important in the method of forming extremely fine continuous filaments within the above-mentioned size range which bear upon the economical and commercial production of the fine filaments. Among the important characteristics is the factor of the start up time after a breakout in initiating the formation of the continuous filaments.

Major conditions affecting start-up time are the weight of the head of glass which forms upon break-out of a filament and the lapsed time of formation of the bead until it drops, that is, when the weight of the bead is sumcient to allow the bead to drop.

It is found that the bead drop time must be reduced to a minimum as this lapsed time determines the handling time or downtime in effecting a restart of filament attenuation. Thus, to render the process commercially economical, the handling time, that is, the start-up time must be reduced as low as possible as such wasted or downtime, if excessive, renders the process or method too costly for commercial adaptation.

We have found that the weight of the bead formed at the tip and its period of formation, which determines the drop time, is dependent in a large measure upon the dimensional characteristics of the orifices and configuration of the tip and the surface thereof from which the stream is discharged. FIGURE 5 illustrates an exemplary tip configuration of a character employed in the method and process of producing extremely fine continuous filaments within the size range above-mentioned.

One characteristic of the tip configuration affecting the bead size and drop time is the area of the face or edge of the tip or projection, that is, the area of the annuiar region or marginal edge defining the exit or outlet of the passage in the projection. This diameter is designated in FIGURE 5 at D6 and the annular face area is designated 112. We have found that the marginal edge or wall at the outlet, designated D6 in FIGURE 5, should be made as thin as is practicable, preferably five thousandths of an inch or less to minimize bead drop time and handling time. While the marginal edge or wall may be made of greater thickness in the order of ten thousandths of an inch and produce fine filaments, the increased wall thickness increases the bead drop time and hence tends to increase the start-up or handling time after interruptions due to breakouts.

By reducing the area of the marginal edge or annular tip face, the bead weight and drop time are reduced, which factors directly affect the handling or restarting time.

The spacing between adjacent tips designated S is important in two respects, first, the spacing should be reduced to a minimum to facilitate the use of a large number of tips on one feeder section to form a large number of fine filaments and, second, the distance between adjacent tips must be sufficient to prevent intercontact between adjacent beads formed on the tips in order to minimize the tendency to flooding, that is, the tendency for the molten glass to migrate along the exterior surfaces of the projections or tips.

Other factors affecting bead weight and drop time are the size of the orifice, the length of the orifice, the rate of throughput, and the temperature and hence viscosity of the glass in the feeder and in the orifice, and at the region of the formation of the bead adhering to the annular face of a tip through interfacial tension. It is found that the higher the temperature of glass and correspondingly lesser viscosity, the bead weight may be reduced.

It is desirable that the temperature of the glass in the restricted passage or orifice channel 114 be comparatively high so that the glass is at a low viscosity to promote the delivery of uniform streams from the orificed tips 100.

The size of the orifice channel 114 and its length affect the throughput of glass. The restricted orifice channel 114 is an important factor in metering or regulating the flow rate or throughput of glass and, as the walls of the orifice channel offer resistance to fiow, an increase in the length of the orifice channel reduces the throughput.

With particular reference to FIGURE 5, in the form of tip illustrated therein, a counterbore 116 is provided of larger diameter than the metering channel or orifice 114, the difference between the diameter of the counterbore 116 and the diameter of the tip face 112 determining the area of the annular tip surface.

The bead formation and drop time is a function of the throughput, the pulling speed for forming continuous filaments, within the size range mentioned above, is upwards of eight thousand or more linear feet per minute. In addition to the throughput, the area of the tip edge or face 112 of the tip and the viscosity at which the glass is attenuated to filaments are factors which contribute to the tension or stress set up in the filaments due to the rapid attenuation of the streams.

Another factor bearing upon the throughput is the depth or head of glass in the feeder-melter unit or receptacle and, furthermore, if pressure is exerted upon the glass in the melter-feeder unit, other factors remaining unchanged, the bead forming and drop time is lessened, further reducing the handling or restarting time. In the embodiment illustrated, the head of glass is maintained at the approximate level illustrated in FIGURES 2 and 3 providing a substantially constant head of glass.

If desired, however, the melting and feeder unit may be placed under pressure by a connection with a suitable gas under pressure, gating the chutes 30 and closing the vent 55 so as to maintain pressure on the glass in the unit. However, at the present time, it appears that the increased cost of pressurizing the receptacle would be greater than the savings effected through reduced handling time with a pressurized unit.

While the dimensions of or geometry of the tips or projections may be varied, the following are approximate ranges for various dimensions of the tip and orifice construction which have been found satisfactory in the production of fine filaments in the filament size range abovementioned. With particular reference to FIGURE 5, the flow metering or delivery orifice channel 114 may be of a diameter D1 up to .045 of an inch and preferably less, with or without the counterbore.

The counterbore is usually employed in order to reduce o the wall thickness at the region of the outlet or orifice in order to minimize the area of the tip face or edge 112. Hence the counterbore diameter indicated at D2 may be in the range from the size of the restriction D1 up to a diameter of approximately .060 of an inch. If the counterbore 116 is not used, and the orifice channel or passage 114 continued to the tip as indicated in broken lines at 118 and being of a uniform diameter, the diameter D1 or size of the channel 114 should be increased to compensate for the resistance of the added length of the orifice channel 114 to obtain the same throughput.

With a metering orifice channel 114 in the size range above specified, the diameter D4 of the tip face would be of a dimension to provide a desired area for the annular face 112, preferably of small area. The diameter D1 is dependent upon the diameter and length of the counterbore D2. If the counterbore is not used, and the diameter of the orifice channel 114 is continued to the tip face 112, the diameter D4 may be reduced to a dimension to provide a minimum practical thickness for the wall adjacent the tip face. The thickness LW of the plate portion of the tip section is approximately sixty thousandths of an inch.

The over-all length LT from the planar interior surface 120 of the feeder section 90 is important in that the length bears upon the tendency of the glass to flood over the lower surface of the tip section. With the abovementioned range of dimensions for the orifice channel 114, the counterbore D2 and the diameter of the tip face D4, it is found that the projection from the lower surface of the feeder section 90 may be of a length up to approximately one hundred eighty thousandths for satisfactory operation but is preferably of a lesser length to a minimum at which excessive flooding may occur. It has been found that if the over-all length LT of a tip is shortened, a reduction in the diameter of the orifice channel 114 should be made in order to maintain the same resistance to glass flow.

Another factor particularly affecting the viscosity of the glass in the orifice channel 114 is the angularity of the tapered wall regions 124 defining the tip or projection 100. The projection being generally of the shape shown in FIGURE 5, it Will be noted that at the region adjacent the orifice channel 114, there is a substantial thickness of metal of the tip 100. Due to the thickness of the metal of the tip or projection at this region, the glass will be at its maximum temperature in the orifice channel and hence at its lowest viscosity to promote satisfactory fiowability through the orifice channel 114.

From this region downwardly the glass loses heat more rapidly through radiation and convection so that the glass at the region of the tip surface 112 is more viscous than the glass in the metering or orifice channel 114.

When a break-out occurs, a bead of glass begins to form under the influence of continued fiowof glass through the orifice passage or channel 114 and, by reason of the surface tension and afiinity of the glass to cling to other bodies, the bead 130 is built up in size by gravity flow. As the bead weight increases, the bead moves downwardly to a broken line position, as shown at 130', and the region of the glass adhering the bead to the tip surface begins to neck in as shown in broken lines at 132.

When the weight of the bead exceeds the force holding the bead in suspension from the tip face 112, the bead drops and, during its descent by gravity, attenuates a continuous thread or monofilament from the glass adhering to the tip face 112. This trailing monofilament enables the operator to effect a restarting by gathering this bead-attenuated monofilament with the other filaments and initiate start-up by winding the filaments on the rotating collector sleeve 18 and restore high speed production attenuation of the streams into fine filaments.

From the foregoing it will be apparent that the bead formation time, that is, the time from its inception after 9 a break-out until the bead drops by gravity to form a bead-attenuated monofilament, determines the lapsed or down time until the attenuating process can be restarted by the operator in the manner above-described. Thus, one of the important factors of the invention resides in the correlation of the factors above-mentioned in a manner to reduce, insofar as possible, the bead forming or bead drop time as this factor determines the handling time in initiating start-up, and reduction of this time renders possible the commercial use of the process on an economical scale. An important factor in reducing the bead forming and drop time is the area of the annular edge or tip face 112. The area of this face should be reduced to a minimum practicable for satisfactory attenuation. Another reason for maintaining the tip face diameter D4 as small as possible is to enable the use of a greater number of tips or projections on a tip section area in order to form a strand or yarn having a large number of extremely fine filaments or ends.

Heretofore continuous filaments of a diameter of twenty hundred thousandths of an inch and filaments of larger sizes have been produced commercially. In applying the methods that have heretofore been used in producing strands of filaments of twenty hundred thousandths of an inch in diameter or larger to the formation of extremely fine filaments in the order of fourteen hundred thousandths of .an inch, the bead drop time has been found to be at least six minutes or more in duration and hence, when a breakout occurred, it required a minimum of twenty minutes or more to restart the attenuating operation.

In the process of our invention the bead formation and drop time has been reduced to about one minute and the handling time thereby reduced to about two minutes. This substantial decreasein handling time makes possible the commercial production of the extremely fine filaments less than eighteen hundred thousandths of an inch in diameter.

While the tip section illustrated in the drawings is of rectangular shape, it is to be understood that a tip section of other shape, or a group of tip sections arranged in close relation, may be employed for carrying out the method of the invention.

When fine filaments of the size less than eighteen hundred thousandths of an inch in diameter are combined in a strand or yarn, a textile material is provided which has a very high degree of flexibility and is much stronger per unit of cross-sectional area than glass fiber yarns heretofore produced. We attribute the improved flexibility and strength characteristics to the fineness of the filaments. It has been found by actual tests that the mechanical properties of a fabric formed with the new fine filament yarns are a high burst strength, improved flexibility, higher resistance to abrasion, higher breaking strength and improved washability, improved wearability and better folding resistance. It is known that glass yarns and textile materials of glass fibers or filaments tend to irritate the skin.

It is found that the strands, yarns or fabrics formed therefrom embodying the new fine filaments of the in vention materially reduces the irritation factor. It has further been found that the yarns or threads formed from the new fine filaments are of such high flexibility that they may be readily processed on conventional knitting and weaving machines.

The uniformity or homogeneous character of glass utilized in forming the fine filaments is a contributing factor to the success of the process. Uniformity of the melt and more especially its laminar characteristics are dependent in a large measure upon the residence time of the glass in the melter and feeder unit in the heat-conditioning phase of the process. Hence it is essential to maintain a substantial quantity of molten glass in the melter chamber 60, approximately at the level illustrated in FIGURES 2 and 3. While a particular glass composition employed in the process may have some effect on the formation and drop time of a bead, it has been found that filament-forming glass compositions of conventional character may be employed although certain percentages of the ingredients or components in the composition may be modified or varied to change or modify the viscosity characteristics in a minor degree but it is not essential to successful attenuation of the fine filaments to employ a glass of special specifications.

The use of a counterbore D2 is to reduce the wall thickness of the tip or projection at the outlet region in order to minimize the area of the annular tip face 112 to facilitate the use of a substantial amount of metal surrounding the metering restriction or channel 114 to minimize the thermal losses at the region of the tip or projection defining the channel. It is therefore desirable to make the counterbore D2, where it is used, of a short length so as not to impair the thermal environment at the tips in order to maintain uniform throughput.

In reference to head drop time as affecting the duration of start-up or handling time, it is to be understood that the bead drop time of an individual glass stream should be as of short duration as possible. In the use of several hundred tips on a feeder, the individual bead drop time is not fully determinate of the start-up or handling time for the several hundred filaments.

For example, tests have shown that with a feeder equipped with 408 outlets or orifices and a bead drop time from a single orifice of six minutes, the handling or start-up time, that is, the time required for an operator to gather all of the 408 filaments into a strand and initiate winding of the strand upon a winding collet, consumes approximately twenty minutes or more. Hence, the handling or start-up time is of greater duration than the bead drop time for the reason that repeated starts may be necessary due to breakage of one or more of the fine filaments during the gathering of the filaments into a strand and its initial Winding on the winding collet.

With our invention, the bead drop time has been reduced to approximately one minute, and for a feeder having 408 orifices, the handling or start-up time is only about two minutes. If a greater number of orifices or outlets is provided on a feeder, the average handling or start-up time is increased due to the greater probability of difficulties in gathering the larger number of filaments into a strand and initiating winding of the strand. Hence the handling time is a function of the number of streams and hence the number of filaments to be embodied in the strand.

In the use of our invention, Where the bead drop time is reduced to approximately one minute, the average handling or start-up time for a group of filaments from a feeder having 408 orifices is reduced to approximately two minutes because of the reduced tendency for breakout of filaments by reason of the several factors such as the high degree of homogeneity of the glass, the thermal environment and the geometry of the tips including the reduction in the area of the tip faces or edges 112.

While fine filaments may be produced where the thick ness of the wall of the tip adjacent the tip face is greater than five thousandths of an inch, the increase in area of the tip face promotes an increase in the bead drop time and a proportionately greater increase in the start-up or handling time. The frequency of occurrence of breakouts and hence the number of start-ups have a direct bearing upon the cost of producing fine filaments so as to render the process commercially economical. It is therefore a general principle of the invention to correlate the various factors and the geometry of the tip section or feeder section to promote a minimum of head drop time and hence reduce the handling or start-up time to render the process commercially feasible.

While the arrangement shown in FIGURES'I through 3 is particularly adapted for processing preformed marbles or spheres of glass int-o extremely fine glass filaments, it

is to be understood that the process may be utilized with the forehearth of a melting furnace in which arrangement molten glass would be delivered to the feeder tip section with a proper quantity in a feeder section providing for sumcient residence time for the glass to properly heat-condition the glass for attenuation into fine filaments.

It is apparent that, within the scope of the invention, modifications and different arrangements may be made other than as herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

We claim:

1. A stream feeder for flowing streams of molten glass from a supply comprising a planar feeder section formed of high temperature resistant metallic material, a plurality of spaced metallic tips depending from the planar section, each of said tips being formed with a metering passage of circular cross-section and a tip face of annular configuration, the diameter of the tip face being not more than twenty thousandths of an inch greater than the diameter of the outlet of the metering passage.

2. A stream feeder for flowing streams of molten glass from a supply comprising a planar feeder section formed of high temperature resistant material, a plurality of spaced tips integral with and depending from the planar section, each of said tips being formed with a passage of circular cross-section and an annular tip face of comparatively small area, the diameter of the tip face being not more than seventy thousandths of an inch, adjacent tips being spaced apart a sufficient distance whereby beads of molten glass suspended from the tips are maintained out of contact and thereby avoid flooding of the feeder section.

3. Apparatus for forming continuous fine filaments of heat-softened mineral material including, in combination, a stream feeder arranged to contain a supply of the heat-softened material in a flowable condition, said stream feeder having a floor formed with a plurality of depending projections of uniform length, each of said projections being formed with a restricted passage having a discharge outlet not exceeding sixty thousandths of an inch in diameter, the extremity of each projection being of a diameter not exceeding seventy thousandths of an inch, said projections being spaced whereby beads of the softened mineral material suspended from the projections are in close relation but out of contact to prevent flooding.

4. A stream feeder for flowing streams of molten glass from a supply comprising a planar feeder section formed of high temperature resistant material, a plurality of spaced tips integral with and depending from the planar section, each of said tips being formed with a passage, the marginal edge defining the outlet of the passage being of a thickness not greater than five thousandths of an inch.

5. Apparatus for forming continuous fine filaments of heat-softened mineral material including, in combination, a stream feeder arranged to contain a supply of the heat-softened material in a flowable condition, said stream feeder having a floor formed with a plurality of depending projections of uniform length, each of said projections being formed with a restricted passage having a discharge outlet not exceeding sixty thousandths of an inch in diameter, the thickness of the wall of the projection at the discharge outlet being not more than ten thousandths of an inch.

References Cited by the Examiner UNITED STATES PATENTS 1,427,014 8/1922 Von Pazsiczky l1 1,796,571 3/1931 Mathieu 18-8 2,846,157 8/1958 Stephens et a1 651 X 2,947,027 8/ 1960 Slayter 65-4 2,996,758 8/1961 McFadden 65--1l 3,066,504 12/1962 Hartwig et a1. 65-l 3,192,023 6/1965 Stalego 65l FOREIGN PATENTS 763,160 12/1956 Great Britain.

DONALL H. SYLVESTER, Primary Examiner.

C. VAN HORN, R. LINDSAY, Assistant Examiners.

Claims (1)

1. 4. A STREAM FEEDER FOR FLOWING STREAMS OF MOLTEN GLASS FROM A SUPPLY COMPRISING A PLANAR FEEDER SECTION FORMED OF HIGH TEMPERATURE RESISTANT MATERIAL, A PLURALITY OF SPACED TIPS INTEGRAL WITH AND DEPENDING FROM THE PLANAR SECTION, EACH OF SAID TIPS BEING FORMED WITH A PASSAGE, THE MARGINAL EDGE DEFINING THE OUTLET OF THE PASSAGE BEING OF A THICKNESS NOT GREATER THAN FIVE THOUSANDTHS OF AN INCH.

Images