CA1059766A - Method and apparatus for processing glass - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A method of forming glass fibers includes maintaining heat-softened glass at a perforated planar area of a thin metallic plate, establishing pressure of the heat-softened glass and extruding the glass by the pressure through the per-forations forming streams of glass. A stream of gas is direc-ted upwardly into contact with the perforated area of the plate for transferring heat away from the plate at a temperature lower than the temperature of the heat-softened glass adjacent the plate to promote the delivery of discrete streams of glass from the perforations without flooding of the glass at the perforated planar area, and attenuating the streams of glass to fibers. Apparatus for carrying out the aforesaid method is also disclosed.

Description

~1~597~

This invention relates to a method of and appara-tus for processing glass and more especially to a method of flowing fine streams of glass from openings or orifices in a feeder plate under an environment and conditions where-in the individual streams may be attenuated to continuous filaments and the tendency for the glass to flood at the eeder plate substantially reduced or eliminated.
~ It has been a practice in the formation of fibers - or filaments from heat~softened glass to flow a plurality of streamsof glass from a supply in a stream feeder or bushing through passages or orifices provided in projec-tions integral with and depending from the floor of a feeder, the orificed projections being spaced a substan~
tial distance one from another whereby individual or dis-crete streams are formed which may be attenuated to fila~
ments, the spaced apart projections tending to prevent flooding of the glass over the stream delivery section of the feeder.
In arrangements of this character for flowing a substantial number of streams of glass to provide a sub-` stantial number of filaments in a strand, a comparative-ly large stream feeder is necessary to accommodate the spacing between adjacent orificed projections in order to prevent flooding, and in order to facilitate the for-mation of beads of glass which fall by gravity with at-tendant trailing filaments which are manipulated by the operator to effect winding of a strand of the filaments upon a rotating collector to form a package. A stream feeder or bushing of this character is necessarily of comparatively large size and, being fashioned of platinum ~`
..~ ., ~05976~6 or an alloy of platinum/ renders filament production expensi~e particularly where a large number of fila-ments are grouped in a single strand. The convention-al stream feeder bushing is fashioned with a floor and walls of substantial thickness in order to with-stand the pressure head of molten glass contained in the feeder or bushing and to fa¢ilitate accurate tem-perature and viscosity control of the glass. The mol-ten glass within the feeder or bushing is at a compara-tively high temperature and hence low viscosity in order that substantially uniform streams of glass flow from the orificed projections for attenuation to fine filaments of uniform size. While the use of spaced orificed projections depending from a feeder floor re-duces the tendency for the glass to flood over the sur-face of the feeder, under certain conditions the glass will flood along the surface oE the feeder and inter-rupt stream flow and attenuation.
The present trend in the production of te~tile strands of glass filaments is to simultaneously attenu-ate a large number of fine filaments from streams of molten glass and combine them into a single strand. In order to attain an increased number of streams from a feeder, the size of the stream feeder or bushing must be increased. Many difficulties are encountered in increasing the feeder size, such as the tendency for the floor of the feeder to sag and the difficulties of maintaining uniform temperature and hence viscosity of a comparatively large body of glass at the stream flow section of a feeder.

~597~6 It is an object of the present invention to obviate or mitigate the above disadvantages.
According to the present invention there is pro-vided a method of forming glass fibers ~omprising pass-ing separate streams of molten glass through an orifice plate heated by orifice plate heating means, said ori-fice plate having at least four rows of orifices there-in, the orifices being spaced in flooding relationship, drawing a glass fiber from the molten glass at each ori-fice and directing a bulk flow of rapidly mo~ing gas upwardly to the orifice area in said plate, said bulk 10w being in an amount and at a velocity and angle sufficient to provide stable fiber formation and to pre-vent flooding of molten glass o~er the orifice area~
Preferably said gas ~low is directed at an angle in the range of approximately ~Erom 40 to 50 to said plate. Expediently the gas is a non-reducing gas, con-viently air.
The invention also provides apparatus for form-ing glass ~ibers comprising means for containing a head of molten glass, an orifice plate, constructed o~ a heat resistant material and disposed at the base of said con~
taining means, having oriice plate heating means, said orifice plate having at least fou~ rows of orifices therein and the orifices being spaced in flooding rela-tionship, means for controlling the temperature of said plate, means for withdrawing glass fi~ers from said plate from molten glass at said orifices, and means dis-posed below said plate for communication with a supply `~ ~

1~5~766 of gas for directing a bulk flow of rapidly moving non-reducing gas upwardly to the orifice area in said plate, said bulk flow being in an amount and at a velocity and angle sufficient to provide stable fiber formation and to prevent flooding of molten glass over the orifice area.
In one embodiment the plate is maintained at a lower temperature than that of the glass at the stream flow region and regulated pressure is e~erted on the glass at the stream flow region to provide streams of substantially uniform size, the glass being o a visco-sity suitable for attenuating the streams into fine con~
tinuous filaments. Thus individual or discrete streams of glass in closely spaced relation are provided which do not tend to adhere one to another. The stream feeder plate can have a comparatively large number of small orifices or openings in closely spaced relation, several stream flow units of this character may be employed con-comitantly to provide a group of streams of glass from each of the units, the groups of streams being attenua-~ed into filaments and ~ilaments of the several groups combined to form a strand or strands by converging the groups of filaments from the several units into one or more strands, each strand containiny a substantial number of continuous filaments. Thus a large number of streams of glass is delivered from a small area thereby greatly reducing the cost of filament forming apparatus and providing a compact arrangement facilitating the concomitant use of several o the fiber forming units to produce one or more strands of ~lass filaments eoonomically.

-~' ~C)5~766 The invention will be further understood from the following description by way of example of embodi-ments thereof with reference to the accompanying draw-ings, in which:-Figure 1 is a semischematic view illustratingone form of arrangement for producing a strand of fila-ments of glass;
Figure 2 is a sectional view illustrating the form of fiber forming apparatus shown in Figure l;
Figure 3 is a ~ottom plan view of the arrange-ment shown in Figure 2;
Figure 4 is a bottom plan view of the stream flow member shown in Figures 2 and 3;
Figure 5 is a view similar to Figure 2 illus-trating a modified arrangement of heating the glass;
Figure 6 is a view similar to Figure 5 illus~
trating another method o~ heating the glass;
Figure 7 is an isometric view illustrating another form of apparatus;
Figure 8 is a lengthwise sectional view of the construction shown in Figure 7;
Figure 9 illustrates a plurality of fi~er form-ing units shown in Figure 2 utilized for forming a multi-filament strand having a comparatively large number of filaments;
Figure 10 is a sectional view illustrating a modified form of stream flow apparatusS and Figure 11 is a sectional view illustrating a further form of stream flow apparatus.

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~ID59766 Referring to the drawings in detail and ini-tially to Figure 1, there i5 illustrated an arrange-ment or apparatus for feeding streams of heat-softened glass, the streams being drawn into fine filaments by suitable attenuating means. In the form of apparatus illustrated in Figure 1, the stream feeding construc-tion or unit 10 is supported by a frame construction 12, the unit 10 embodying means adapted to heat an ad-vancing glass rod 14 to soften the glass to a mobile : 10 condition whereby streams 16 of glass are delivered : through small orifices in a feeder plate or member 18.
The glass rod 14 is fed downwardly into the unit 10 at a comparatively low rate by suitable feed rolls 20 rotated through conventional transmission gearing contained in a housing 24 and driven by a motor 26. The glass rod 14 is fed at a controlled rate to exert sufficient pressure upon the heat-softened or mobile glass of the rod in the unit 1~ for extruding

2~ streams of the glass through orifices ln the plate 18.
The speed of rotation of the feed rolls may be varied and controlled by conventional adjustable variable speed mechanism inthe transmissionhousing 24or by regulating L

~59766 the speed of the drive motor 26.
As shown in Figure 1, the streams 16 of glass delivered or extruded through the orifices 18 are attenuated into discrete filaments 30 which are converged by a gathering shoe 32 into a group or strand 34 and the strand wound into a package upon a thin-walled packaging tube mounted on a winding mandrel 36 of a winding machine 38, the winding collet being driven in a conven-tional manner by a motor 40. The size of the filaments 30 may be varied by varying the size of the glass streams or modifying the linear rate at which the streams are at~tenuated into filaments.
It is to be understood that, if desired, the filaments may be engaged with a conventional single pull roll or engaged with nip rolls of conventional character rotated at filament attenuating speed and the filaments collected upon a conveyor to form a mat or other form for further processing.
Figures 2 and 3 illustrate on a larger scale the glass stream feeding apparatus of Figure 1. The apparatus is inclusive of a tube or tubular member 44 of metallic material resistant to high temperature such as an alloy of platinum and rhodium, the tube providing a chamber to contain the glass. The internal diameter of the tube 44 is slightly larger than the diameter of the glass rod 14 providing the glass supply whereby the rod is snugly but slidably movable in the feeder chamber provided by the tube 44. Welded or otherwise secured to the lower end of the tube 44 is a circular disc or member 46.
Welded to an upper region of the tube 44 is a similar disc 48, the discs 46 and 48 being of an alloy of platinum and rhodium or other metallic material resistant to high temperatures.
~lso surrounding the tube 44 adjacent the disc 48 is a circular frame member 50 which is secured to and forms a component of the ~059766 supporting frame structure 12. Depending from the periphery of the member 50 is a circular metal member 52 supporting an annular metal member or ring 54. Disposed adjacent and below the ring 54 .
; is a circular disc or element 56 having a counterbore 58. The member 56 is supported from the ring 54 by bolts 57.
Disposed in contiguous contact with the platinum alloy disc 46 is a stream flow member, body or plate 60 having a perfor-ated stream flow area 62 provided by a comparatively large number of openings or orificés 64 in the plate 60, as particularly shown in Figures 3 and 4, the stream flow area being in registration with the interior of the tube 44.
The stream flow plate 60 is preferably comparatively thin and is supported by a plurality of discs or washers 66 of refrac-tory nested in the counterbore 58 in the member 56. Disposed in a circular recess 70 provided in the member 56 is a blower or nozzle construction comprising a circular member 72 having a central passa~e 74 which registers with the circular central openings of the insulating washers 66.
; The member 72 is supported from the member 56 by screws 73. The circular member 72 is fashioned with a circular recess 76 which, with a surface 78 constituting the bottom of the recess 70, forms a circular manifold. An innermost circular region of member 56 is fashioned with a frusto-conically shaped surface 80.
An inner circular portion 82 of member 72 is fashioned with a reciprocally- shaped frusto-conically shaped surface 84 which, as shown in Figure 2, is spaced slightly from the frusto-conically shaped surface 80 to provide a circular orifice, nozzle or slot 86 for directing air from the manifold 76 upwardly into contact with the lower surface of the plate or body 60 to reduce the temperature of or cool the plate 60.

lC~S9766 The circular manifold 76 is connected by tubes or tubular members 90 and 91 with a blower 94 or supply of air under pressure.
The entrance 96 of the tubes 90 and 91 into the manifold 76 are preferably tangential, as shown in Figure 3, to impart a spiral path of traverse to the air in the manifold 76 and to the air delivered through the slot or orifice 86 for contact with the plate 60.
The glass of the rod 14 is heated as it moves downwardly through the tube 44 whereby the glass adjacent the plate 60 is in a softened mobile condition. In the form shown in Figure 2, the glass of the rod 14 is heated to reduce the same to a mobile or flowable condition by resistance heating, that is, flowing electric energy through the tube 44 and the glass within the tube. Welded or otherwise joined to opposed wall regions of the tube 44 are terminals or terminal lugs 100 engaging the tube 44 throughout a substantial portion of its length. Terminal connectors 102 of conventional character are connectecl with the lugs 100 and with a supply of controlled electric current of high amperage and com-paratively low voltage.
! 20 The flow of electric current through the tube 44 and the glass of the rQd 14 is e~fective to progressively increase the temperature of the advancing rod 14 whereby the glass approaching the region of the plate 60 is softened and in a mobile condition, the softened glass being of a viscosity facilitating delivery of streams of the glass under pressure through the orifices 64 in the plate 60. In order to minimize heat losses from the glass and the tube 44, the tube is imbedded or embraced within high temperature resistant refractory 106 as shown in Figure 2~
The member 56 is fashioned with a circular passage 108 to accommodate a cixculating cooling fluid, such as water. Water _ g _ ~C3S9766 flows into the circular passage 108 through an inlet fitting 110 and out of the passage through an outlet fitting 112, there being a baffle 114 in the passage 108 between the inlet and outlet to promote circuitous flow of cooling fluid in one direction through the circular passage 108. The cooling fluid absorbs heat from the member 56 and associated components in order to maintain them at a safe operating temperature.
The method of operation of the arrangement shown in Figures 1 through 4 is effective for extruding or delivering streams of heat-softened glass through the orifices 64 under con-ditions avoiding flooding of the glass across the lower surface of the feeder plate 60. As an example of the size and close spacing of the stream flow orifices in the plate 60, discrete streams of glass are,delivered through orifices ~4 of about ten thousandths of an inch in diameter, the orifices being arranged in rows, as shown in Figure 4, and the center lines of adjacent rows being spaced about twenty-five thousandths of an inch apart without encountering flooding when the plate 60 is maintained at a temper-ature lower than that of the glass at the stream flow region of the plate by air from the blower.
In operation, a rod of glass 14 is advanced at a con-trolled rate by the rotating feed rolls 20 into the tube 44 which ~' provides a melting chamber. As the glass rod moves downwardly into the tube 44, the glass lS progressively increased in temperature by electric current flow through the glass. The glass upon reaching the region 61 above and ad~acent the plate 60 is softened to a sufficiently low viscosity to facilitate flow of streams of glass under pressure through the orifices 64.
In the method of operation of the arrangement shown in Figures 1 through 4, the speed of rotation of the feed rolls 20 is ~_~ci~766 controlled or regulated so as to exert a downwardly acting pressure on the softened glass adjacent the feeder plate 60, the pressure extruding the molten glass at the region 61 through the orifices 640 A stream of air is concomitantly delivered through the circular slot or orifice 86, the air being proje~ted upwardly into contact with the plate 60 to continuously cool the plate whereby the plate is maintained at a temperature below the -temperature of the glass in the region 61.
It is found that for a glass, such as conventional "E"
glass, a temperature differential between the temperature of the softened glass at the region 61 and the temperature of the plate should be between 50CF and 150F,the tempeEature differential being maintained substantially constant by regulating or controlling the delivery of air from the blower slol: 86 by a valve or damper 95, shown in Figure 3, in the air supply manifold. When these con-ditions obtain it is found that there is no flooding of the glass encountered at the lower surface of the plate 60 and the streams of glass are maintained discrete and separ~te even though the streams are in very close relation.
As an example of the operating temperatures in the utilization of "E" glass in forming streams for attenuation to filaments, the plate temperature may be between 2050 F and 2100 F
with the glass at the region 61 of a temperature not less than 2150 F.
The temperature of the plate 60 may be regulated and controlled by modifying the amount of air delivered in a given unit of time through the slot 86, the amount of air being con-trolled by the valve or damper 95.
It is further found that the glass at the region 61 ~S9766 should be under pressure sufficient -to effect continuous extrusion of the glass through the perforations or orifices 64 as well as to attain the desired throughput of glass per unit of time through the fiber-forming unit. It is further found that the plate 60, which preferably is an alloy of platinum and rhodium or other metal resistant to the high temperatures, may be comparatively thin being not less than .002 inches in thickness and preferably of a thickness of .005 of an inch or more depending upon the viscosity of the glass, the pressure exerted on the glass, and the temperature dif-ferential to be maintained between the plate and the molten glass adjacent the plate.
In the use of a comparatively thin stream flow plate, the perforated area is comparatively small so as to provide sufficient structural strength to withstand a downward pressure of the glass of about fifteen pounds per square inch without rupture.
The pressure of the glass on the plate 60 may be between three pounds and twenty pounds per square inch. If a plate 60 of greater thlckness is used, the glass pressure may be increased to secure increased throughput.
Figure 5 illustrates an arrangement similar to Figure 2 but wherein the glass rod is heated by induction. The rod 14' of glass is delivered downwardly at a controlled rate by rotatable feed rolls 20'. The rod of glass moves through a chamber provided by a tube 44' of an alloy of platinum and rhodium or other high temperature resistant metallic material.
The frame structure supporting the stream flow unit includes frame members 12' and a disc 50' engaging a circular member 48' of platinum alloy welded to the tube 44'. A circular member or sleeve 52' depending from the disc 50' supports a ring 54'.

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~OS~766 The ring 54' supports a circular member or disc 56' and an air blower manifold 72'. A perforated stream feeder plate or member 60' is disposed contiguous with the lower surface of a disc 46' of platinum rhodium alloy welded to the lower end of the tube 44'. The central area 64' of the feeder plate 60' is provided with rows of comparatively small perforations as shown in Figure 4, through which streams of glass are delivered in the same manner as described in connection with the form shown in Figure 2. Wall regions of the manifold chamber76' in the manifold 72' are fashioned with frusto-conically shaped surfaces defining an upwardly slanted circular slot or orifice 86' through which air is delivered from a blower, such as the blower shown at 94 in Figure 3, into contact with the plate 60' to cool the plate.
- The plate 60' is supported by discs or washers 66' of high temperature resistant refractory, the wachers being supported by the member 56'. The member 56' has a circular passage or chamber 108' through which cooling water or other heat-absorbing fluid is circulated to maintain the disc 56' and associated com-ponents at a safe operating temperature. The tube 44' is surroun-ded by an inductive heating unit or coil 120 supplied with electriccurrent from a controlled source (not shown) through current con-ductors 121 in a conventional manner.
The induction heater coil 120 is positioned as close as practicable to the tube 44'. The induction heating coil is sur-rounded by high temperature resistant re~ractory 122.
The operation of the arrangement shown in Figure 5 is substantially the same as the operation of the form shown in Figure 2. The induction heater 120 progressively increases the temperature of the glass of the advancin~ rod 14' whereby the lower portion of the glass of the rod is reduced to a softened ~5~766 flowable or mobile condition at the region 61' above the plate 60', the softened glass at the region of transition of the glass to a softened state engaging the wall of the tube 44' provides an effective seal so that constant pressure exerted on the rod 14' by the feed rolls 20' will effect extrusion of the heat-softened or flowable glass at the region 61' through the orifices at the area 64' of the plate 60'.
The air stream delivered through the circular slot a 6' contacts the plate 60' and maintains the plate 60' at a tempera-ture lower than that of the glass at the region 61'. The glassstreams extruded through the orifices at the perforated region 64' form discrete streams and the glass does not flood across the lower surface of the plate 60' during attenuation of the streams to filaments~
Figure 6 shows an arrangement similar to Figure 5 illus-;~ trating another method and means of heating the advancing glass rod to reduce the glass to a mobile or flowable condition at the region adjacent the stream feeder plate.
In this form the glass rod 14a is advanced b~ rotatable feed rolls as in the other forms of apparatus to advance the glassrod through a tube 44a fashioned of an alloy of platinum and rhodium or other suitable material. Welded to the tube 44a at its upper region is a circular disc 48a and at its lower end a similar disc 46a.
Depending from the frame component 50a is a circular wall 52a supporting an annular member or ring 54a. A circular member 56a is supported from the ring 54a by bolts 57a. The stream feeder plate 60a of the same character as shown in Figuxes 2 and 5 supported in contiguous engaging relation with the disc 46a by annular members 66a of refractory nested in a recess provided in ,,.

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., ., ~

~05976~

the member 56a. A blower manifold 72a supported by member 56a is fashioned with a mani~old chamber 76a.
The innermost regions of the blower member 72a and the member 56a are shaped to provide a circular blower orifice or slot 86a through which air from the manifold chamber 76a is pro-jected upwardly into contact with the plate 60a for cooling the plate to a temperature below that of the glass at the region 61a adjacent the plate 60a. The member 56a is provided with an annular chamber 108a to accommodate a circulating heat-absorbing fluid such as water to maintain the member 56a at a safe oper-ating temperature.
In the form of apparatus illustrated in Figure 6, an internal combustion burner provides the means for heating the glass of the rod 14a as it moves downwardly to reduce the lower end region of the rod to a softened or mobile state, the softened glass being of a temperature and viscosity whereby streams of the glass may be extruded through the perforated or orificed area 64a of the plate 60a. The combustion burner is of annular shape and surrounds the chamber provided by the tube 44a. The burner is fashioned with a lining preferably of refractory 134 defining an annular combustion chamber 136.
A circular rear wall 138 of the combustion chamber is formed with a plurality of small passages 140 to admit combus-tible mixture of fuel gas and air from an annular manifold 142, the perforated wall 138 forming a fire screen to prevent igni-tion of the mixture in the manifold 142. Combustible mixture ; ~ is delivered to the manifold 142 from a supply through a pipe , 144, a valve means 146 being disposed in the supply pipe for regulating the delivery of mixture to the burner. The mixture is introduced into the combustion chamber 136 under comparatively :

:,.

., ~ A
., ~C3 59766 low pressure of about five pounds per square inch, and the mix-ture ignited and burned in the chamber 136.
The heat of the burning gases in the annular chamber 136 heats the glass rod 14a as it is advanced through the tube 44a, the lower end region of the glass rod being reduced to a softened or flowable condition by the heat from the chamber 136.
The gases of combustion flow upwardly through an annularly-shaped chamber 137 forming a continuation of the chamber 136, the hot gases in the chamber 137 progressively in-creasing the temperature of the advancing glass rod 14a. Thegases from chamber 137 are exhausted from chamber 137 through one or more exhaust pipes 150 for discharge at a region remote from the burner.
In the arrangement shown in Figure 6, the glass rod is progressively heated and becomes softened in the lower region ; 61a of the chamber provided by the tube 44a to a viscosity suitable for delivery under pressure through the orifices to provide the streams 16a of glass fox attenuation to filaments 30a. Through the continuous delivery of a stream or jet of air through the circular orifice 86a from the manifold chamber 76a, the plate 60a is maintained at a temperature below the tempera-ture of the molten glass in the region 61a above the plate and wetting or flooding of the lower surface of the plate by the glass is substantially eliminated or prevented. The control of the heating of the glass is exercised by manipulation of the valve 146 regulating the combustible mixture delivered into the burner chamber 136.

Figures 7 and 8 illustrate another arrangement ~or carrying out the method of extruding streams of glass through closely oriented or spaced orifices in a feeder plate utilizing ..

~L05'37~6 a substantially rectangular glass body or plate of glass as a supply, is fed toward the feeder plate and the glass being pro-gressively increased in temperature as it is fed or advanced toward the stream feeder plate and reduced to a softened or mo-bile state at a region above and adjacent the feeder plate.

; In this form the--chamber recei-ving and containing the glass is provided by a tubular member 160 formed of an alloy of platinum and rhodium or other high temperature resistant material, the member being of substantially rectangular cross section.
The interior dimensions of the tubular member 160 are such as to snugly, yet slidably, receive and accommodate a glass supply in the form of a glass plate 164 which may be advanced into the tube 160 by conventional feed rolls (not shown) engage-able with opposed wall surfaces of the glass body and driven at a controlled rate to advance the glass body into the tube at the rate at which the glass is extruded or delivered through orifices in a feeder plate. Surrounding the upper region of the tube 160 is a laterally extending rectangular shaped collar 166 which may be secured to frame members such as frame members 12 shown in Figure 2 for supporting the tube 160.

A similar rectangular shaped member 168 is disposed a~ the lower end of the tube 160 and is preferably welded to the lower end of the tube. A stream feeder plate 170 is con-tiguous with the lower surface of the member 168, the region of the member 170 in registration with the interior of the tube 16 being fashioned with rows of small orifices 172 in closely oriented or spaced relation. The orifices 172, for example, may be about ten thousandths of an inch in diameter arranged in rows of about twenty-five thousandths of an inch between centers of i~ 30 adjacent orifices in a row, and the rows spaced on center lines ,:,.

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1~59766 about twenty-five thousandths of an inch apart.
Disposed beneath the feeder plate 170 are spacers or rectangularly-shaped washers 174 of refractory which are nested in a suitable recess in a rectangularly-shaped member 176 sus-pended from the frame members by supports or rods 178. A sub-stantially rectangular blower member 180 is disposed in a recess in the member 176, the blower being of substantially the same general construction as the blower illustrated in Figure 2 but is of rectangular shape.
The blower member 180 is fashioned with a manifold chamber 182 provided with interior angularly disposed surfaces 184 which with angularly disposed surfaces 186, fashioned on member 176, pro~ides a slot or orifice 188 of substantially rec-tangular configuration to deliver a stream of air onto the plate 170 to cool the plate. The rectangular member 176 is provided with a peripheral passage or chamber 190 preferably of rectan-gular shape by reason of the rectangular shape of the member 176. The passage or chamber 190 accommodates circulating cooling fluid to maintain the member 176 at a safe operating temperature.
In this arrangement the end walls 161 of the rectan-gular tube 160 are provided with terminal lugs 192 and 194 for connection with current supply conductors for supplying elec-tric current to the tube 160 for heating the body of glass 164 being fed downwardly through the tube 160. The current supply to the terminals 192 and 194 is controlled by conventional means to regulate the heating of glass of the body 164 whereby the lower region of the glass 196 adjacent the feeder plate 170 is in a softened and mobile condition. The tube 160 may be surrounded with refractory (not shown~ to minimize heat losses.

~L059766 In the operation of the arrangement shown in Figures 7 and 8, the preformed glass plate is advanced by feed rolls (not shown) at a controlled rate and the heating of the glass through the flow of electrical energy through the tube 160 and the glass progressively-increases-the temperature of the glass during its downward movement so that as it approaches the plate 170, the glass is in a softened or mobile condition.

The feed rolls exert pressure on the glass body 164 whereby pressure is exerted on the sof~ened glass at the region 196 adjacent ~he plate 170 whereby streams of glass are extruded through the orifices 172 in the feeder plate 170. As the stream of air delivered through the orifice 188 continuously contacts the plate and maintains the plate at a reduced temper-ature, the glass does not flood across the surface of the plate and the streams remain discrete even though they are in closely oriented relation.

The streams may be attenuated to filaments ~00 by winding the filaments in a strand form upon a rotating col-lector of the character shown in Figure 1, or attenuated byother means, such as a pull roll or nip rolls, in a well known conventional manner. Through the arrangement shown in Figures 7 and 8 7 a comparatively large glass stream flow area is pro-vided in the plate 170 and as the perforated area of the plate is comparatively narrow, being about the width or thickness of . the glass plate or body 164, the plate will withstand the feed pressure.exerted on the glass plate without fracturing. The throughput of glass is substantially increased through the use of a plate or rectangular body of glass as the glass supply.

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~597Ç;~

Figure 9 illus~rates the use of a plurality of fiber-forming units lOb of the character illustrated in Figures 2 and

3 providing for the concomitant attenuation of a plurality of groups of streams of glass extruded from a plurality of fiber-forming units. Each unit lOb is supplied with a glass rod or body 14b delivered by pairs of feed rolls 20b fed into the chambers provided by the tubular members 44b, the glass being heated by electric energy delivered through current supply con-ductors connected with the terminal lugs lOOb, the blower mani-fold members 72b may be supplied with air from a blower through an air manifold pipe 210 connected with an air blowe~r o~ the character shown at 94 in Figure 3, or other supply of air under pressure.

Air from the supply pipe :210 is delivered to each blower through branch pipes 212. The air delivered to each blower may be regulated or controlled by valve means 214 asso-ciated with each of the branch pipes 212. Each unit lOb is ` provided with a feeder plate 60b of the character shown at 60 in Figure 2 for delivering a group of glass streams in closely ; spaced relation from the feeder plate of each unit. The streams are attenuated to filaments 30.

The groups 216 and 21~ of filaments may be converged by a gathering shoe 220 to form a strand 222 comprising the filaments of the several groups, the strand 222 being collected upon a winding collet in the conventional manner. If desired, ' the individual groups may provide individual strands which may be concomitantly wound upon dual collectors or tubes of a winding machine to form two independent packages.

Figure 10 illustrates another form of apparatus for perfDrming or carrying out the method of the invention. In this arrangement the glass supply is maintained in a heat-softened condition at a temperature and viscosity wherein the glass may be readily extruded through one or more groups of orifices in a plate which is maintained at a temperature less than that of the heat-softened glass adjacent the plate. A
walled receptacle 230 for containing the glass, in the embodi-ment illustrated, is of substantially rectangular shape but may be of circular or oval configuration if desired.

The receptacle 230 is provided with a floor or bottom section 234 and with a cover or closure 238 to facilitate pres-surizing the receptacle. The end walls 240 of the receptacle are provided with terminal lugs 242 for connection with current conductor terminals 244 supplying electric current to the re-ceptacle and the glass therein for melting or heat-softening the glass and maintaining the softened glass at a proper vis-cosity for forming the glass streams.

In the embodiment illustrated, the cover 238 is pro-vided with a tubular fitting 246 equipped with means for metering or controlling the delivery of pieces of glass, such as glass marbles, into the receptacle 230. The gating or metering means is of conventional character and comprises a rotatable shaft 248 equipped with gates or vanes 250 contained within a cylindrically-shaped housing member 252, the gates or vanes 250 snugly fitting against the inner wall of the housing 252 to provide a seal. The pieces or marbles of glass ,:

:1~59~6~

are fed to the metering means from a supply (not shown) through ; a tube 254 in a well known conventional manner.

Also connected with the cover 238 or with the recep-tacle at a region above the level of glass in the receptacle is `~ a pipe 258 connected with a supply of air or other gas under ; pressure or maintaining pressure above atmospheric pressure in the receptacle 230 for extruding the glass through orifices ln a feeder plate. The pressure may be controlled by a valve 259 associated with the pipe 258. Positioned contiguous and in con-tact with a lower surface 260 of the receptacle floor 234 is a ~ ~ stream feeder plate 264. The floor 234 is fashisned with spaced ; ~ passages 266 through which glass is delivered to perforated or ~ orificed regions of the plate 264.
.
Disposed in registration with each of the passages 266 are perforated regions 268 of the plate 2641 each region com-prising a comparatively large number of small orifices 270 ; through which the glass is extruded from the feeder chamber 236.
Positioned beneath the stream feeder plate 264 is a series of stacked members 274 of refractory which are supported by a mem-ber 276. The member 276 is provided with a chamber 278 accom-modating cooling fluid to maintain this member at a safe oper-ating temperature. The member 276 is provided with a recess 279 accommodating a blower construction 280.

The blower comprises a member 282 fashioned with a series of circular manifold chambers 284, the member 276 and the 1~5976~

blower m~mber 280 having pairs of cooperating frusto-conically shaped surfaces providing circular orifices 286 ~ounding pas-sages ~88 in the blower member 282, a passage 288 being in registration with each of the passage~ 266 of the floor 234 of the receptacle 230.
The manifold chambers 284 are connected with a ~upply of air under pressure such as the blower g4 shown in Figure 3 or other compressed air supply. Air ~tream~ are delivered th~ough the circular orifices or slot~ 286 into contact with the lower : 10 surface areas of the plate 264 at the perforated regions 268 to reduce the temperature of or cool the plate 264.
Glass marbles are fed at a controlled rate through the marble gating or metering means 250 and the glass reduced to a softened or mobile condi-iion by electric current flowing throu~h the receptacle 23Q ~nd the glass therein. Air or other gas at a con~tant pressure is admitted through the tube 258 thereby pressuring the glass under sufficient pressure to extrude streams of the glass simultan-eously through the orifices 270 at the perforated regions 268 in the plate 264.
The streams of glass delivered from each of the per-forated areas 268 may be attenuated to fine filaments and tl~e groups of filaments from the several areas converged into a strand and the strand wound in~o a package in the manner des-cribed in connection with Figure 1, or the groups of filaments derived from attenuation of the grcups of streams may be con-verged to form two or more strands. Through the arrangement illustrated in Figure 10, a substantial throughput of glass is attained through the use of several groups of stream feeder orifices thereby rendering the process economical. The use ot .~

lOS9766 the stream feeder plate maintained at a temperature below that of the glass avoids flooding of the glass at the lower surface areas of the plate at the stream feeder regions.
Figure 11 illustrates another form of apparatus, the apparatus embodying a mechanical means for pressurizing the heat-softened glass for extruding the glass through open-ings in a stream feeder plate. The arrangement includes a walled receptacle 300 providing a melting chamber 302, the receptacle being fashioned o~ an alloy of platinum and rho-dium or other high temperature resistant metallic material.
$ The receptacle 300 is provided wi$h a cover 304 equipped with tubes 306 through which bodies or marbles of glass are introduced or fed into the chamber 302.
Each of the tubes 306 is connected with metering means such as that shown in ~igure 10 for regulating and con-trolling the delivery of bodies or marbles 308 of glass into the chamber 302. In the arrangement shown in Figure ll,the receptacle 300 is heated by electric current for reducing the glass to a molten or mobile condition. Secured to opposite wall regions of the receptacle 300 are terminals or lugs 310 engaged by current supply conductors 312 connected with a source of electric energy for heating the receptacle, the elec-tric current being regulated by well known conventional means (not shown). A perforated, current conducting heater strip 314 extends across the chambex 302 below the level of the glass to promote heatin~ of the glass.
The receptacle 300 is fashioned with a tube or tubu-lar extension 316 of circular cross section, the tube being of platinum and rhodium alloy and joined to the floor of the receptacle.

~ 24 ' '.'"
, .

~L[)59766 In this form the floor or floor portion 324 of the , ~ receptacle i5 the stream feeder plate or member and may be an , integral portion of the tube 316, the latter providing a cylin-~; drically~shaped chamber 322 containing heat-softened glass.
, ~ The floor or stream feeder plate 324 is provided with a group of small orifices 326 similar to the group of orifices in the plate 60 shown in Figures 2 and 4.
The floor or feeder plate 324 i5 engaged by annular members 328 of refractory, the members 328 being supported in a recess in a member 330 of the same character as the member 56, ,~; shown in Figure 2. A blower construction 332 of the character shown in Figure 2 is supported by a member 330 for delivering a stream or jet of air through a circular orifice 334 into con-tact with the lower surface 336 of the stream feeder plate 324 to cool the plate. The member 330 is supported by suitable frame means (not shown).
The receptacle 300 and the tubular extension 316 are surrounded with reractory 350 to minimize heat losses. The cover 304 is fashioned with an opening accommodating a tubular fitting 352 through which extends a rotatable shaft 354. The end region of the shaft extends into the chamber 322 provided by the tube 316 and is equipped with an impeller 356 of conventional construction, the tips of the impeller blades or vanes being disposed close to the wall of the tube 316 but being rotatable therein in a direction to exert downward pressure on the softened glass in the chamber 322.
The shaft 354 and impeller are driven by an electri-cally energized motor (not shown) of conventional character.
I The speed or rotation of the shaft 354 may be varied and con-trolled by conventional speed reducing mechanism associated with 25 _ ~S~766 the drive motor or by regulating the speed of the motor. Through this arrangement the rotation of the impeller 356 exerts a con-stant pressure on the softened glass in the chamber 322 whereby the glass is extruded in streams through the small orifices 326 in the stream feeder plate 324. The downwardly directed pres-sure on the glass established by rotation of the impeller 356 ;
: may be varied and controlled by regulating the speed of ro-~ tation of the impeller.
,:' In the operation of the arrangement shown in Figure . 10 11, pieces or marbles of glass or glass batch are fed through the tubes 306 into the chamber 302 at a controlled rate equal . to the throughput of glass through the orifices 326. Air under pressure is supplied to the manifold of the blower 332 and a jet or stream of air delivered into contact with the stream feeder plate 324 to reduce the temperature of the plate to between 50F and 150F below the temperature of the softened glass adjacent the feeder plate in the chamber 322.
Electric energy is supplied to the receptacle 300 and heater strip 314 to reduce the pieces, marbles or glass batch to a softened or viscous molten condition, the rate of melting or softening of the glass being controlled by regulating elec-tric current flow to the chamber 300.
The pressurizing impeller 356 is rotated at a speed to develop a downwardly acting constant pressure on the glass in the region 322 whereby the glass is extruded through the orifices 326 in fine streams which are attenuated to filaments in the ; manner illustrated in Figure 1.
The reduction in temperature or cooling of the plate 324 enables continuous delivery of streams of glass through the ',~
- 2Ç -~0~9766 "

: orifices 326 without flooding of the glasg over the surface of ~ the L-late 324 whereby the glas~ streams are maintained in di~-s crete form for attenuation to continuous filaments.
Processing of the glass is performed or carried ; out through the es ablishment and coordination of particular operating characteristics and condition~ whereby stream of ~ glass may be successfully extruded through clo8ely ~paced ,s orifices or openings in a metal body or plate wherein the plate is maintained at a temperature below that of the glas~ adjacent the stream flow region of the plate and the gla~s pre~surized whereby discrete stream~ are formed which ~ay be attenuated to filament~ and without flooding the obver~e surface of the stream feeder body or plate.
; While the reasons for and principles involved in attaining a nonwetting condition may not be fully understood, there are numerous actors or relationships that have been found to be instrwmental in promoting flow of streams of glass without encountering wetting of the stream flow area of a feeder plate during operation and the maintenance of the streams in 20 independent or discrete form so as to facilitate their attenu-ation to filaments. It has been found that several factors or conditions have a bearing upon attaining a nonwetting environ-ment.
One of the factor~ involves the continuous dissipation of heat energy from the stream delivery region or section of the stream feeder plate to establish a substantial temperature dif-' ferential between the softened glass adjacent the plate and the i stream delivery surface of ~he plate. As previously mentioned herein, the temperature of the feeder plate should be between 50 F. and about 150F. lower than the glass temperature.

\~

l~S9766 Another factor bearing upon the success of the method is the maintenance of a proper temperature and hence viscosity of the softened glass at the stream flow section of the plate.
It has been found by test that the viscosity of the glass should be such that the glas5 is in a mobile state but of a viscosity high enough that streams of the glass will not readily flow through the orifices under the influence of gravity but requires comparatively low pressure to extrude the softened glass through the orifices to provide the glass str0ams. It is found that a pressure on the softened glass is required not only to extrude the glass through the orifices but is one of the factors in promoting the nonwetting characteristic.
It has been found by tests that different degrees of tendency toward nonwetting are in a measure dependent on vari-ations in pressure on the glass. Pressures between five pounds per square inch and twenty pounds per square inch in association with other factors will result in continuous stream delivery with virtually no tendency toward wetting of the feeder plate surface or interadhesion between adjacent streams even though they are in close relation. The reduced temperature of the plate results in the plate having a higher contact angle with glass and this factor tends to reduce "wet out".
There are several energies or energy factors believed to be involved in the attainment of satisfactory nonwetting characteristics. Among these eneryies are the interface energy between the metal of the stream feeder plate and the glass, interface energy between the metal and the air stream directed onto the plate for cooling the plate, and the interface energy between the air and the glass at the stream delivery region.

It is believed that a proper balance of these eneryies or forces - 28 ~

1C~59766 results in a stable condition ostering a nonwetting or non-flooding tendency. An imbalance of the energies promotes dif-ferent degrees of wetting of the feeder plate fostering differ-ent degrees in the tendency for flooding to occur.
Another factor that is believed to bear upon the operation of the method is the "wet out" time or rate, this being the time factor within which the molten glass is enabled to move or migrate onto or in contact with an adjacent surface.
It has been found that ~here the softened glass is at a com-paratively low temperature but of a viscosity at which it willmigrate or flow, that the "wet out" time or rate, that is its rate of migration or movement is decreased and hence its faculty `~:
for flooding is lik~wise diminished.
Another factor bearing upon the '/wet out" rate or time is the pressure on the glass tending to extrude or force ; the glass through the orifices in the feeder plate. It is found that if the pressure on the glass is increased, the vel-ocity of the glass extruded through the orifices is increased, thus reducing the "wet out" rate and thereby promoting a non-flooding condition. Furthermore, the high discharge velocities of the glass through the small size orifices provide a substan-tial increase in throughput for the desired fiber diameter as compared with the throughput of conventional larger orifices at reduced glass velocity.
~ From the results of tests in the use of stream feeder ; plates of varying thicknesses, it is found that satisfactory nonwetting or nonflooding condition is attained with a lesser amount of pressure on the glass when a comparatively thin feeder plate is employed. For example, if the stream feeder plate is increased in thickness, then the pressure should be increased ~ 29 . ~5~766 $ in order to attain the same velocity of flow of the glass through ; the orifices in order to provide the same "wet out" rate attained . through the use of a thinner plate and less glass feed pressureO
`. In operation, it is found that where heat energy is being remo~ed or transferred from the stream feeder plate at a ~ ~ substantially constant rate as by directing an air stream into contact with the plate as hereinbefore described, the extruded : streams remain individual and discrete and may be successfully . attenuated into filaments. It is found that when heat is not removed or transferred from the plate at a constant rate as, for example, when the air stream is interrupted, the glass readily floods the orificed area of the feeder plate resulting in the streams becoming ~oined into a single body.
However, when delivery of the air stream is restored and the glass body manually pulled downwardly, the glass immedi-ately separates into discrete or independent streams and no further tendency toward flooding is encountered so long as the feeder plate is maintained at a reduced temperature and the . other operating conditions such as the proper temperature and the viscosity of the glass and the proper pressure maintained on the glass to extrude the streams through the orifices. me rate of extrusion of the glass through the orifices must be constant j ; and coordinated with the linear rate of attenuation of the : streams to filaments in order to secure filaments of uniform ~ size.

':

; 30 _ 30 -.

Claims (13)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of forming glass fibers comprising:
passing separate streams of molten glass through an orifice plate heated by orifice plate heating means, said orifice plate having at least four rows of orifices therein, the orifices being spaced in flooding relationship;
drawing a glass fiber from the molten glass at each orifice; and directing a bulk flow of rapidly moving gas upwardly to the orifice area in said plate, said bulk flow being as an amount and at a velocity and angle sufficient to provide stable fiber formation and to prevent flooding of molten glass over the orifice area.

2. The method of claim 1 wherein said gas flow is direct-ed at an angle in the range of approximately from 40° to 50° to said plate.

3. The method of claim 1 or 2 wherein said gas is a non-reducing gas.

4. The method of claim 1 or 2 wherein the orifice plate is made of a wettable alloy and said gas is air.

5. The method of claim 1 wherein said orifice plate is flat and contains a density of at least about 50 orifices per square inch.

6. The method of claim 5 wherein said gas flow is direct-ed at an angle in the range of approximately from 40° to 50° to said plate.

7. The method of claim 5 wherein said plate contains a density of at least 100 orifices per square inch.

8. The method of claim 5 wherein said plate contains a density of at least about 200 orifices per square inch.

9. The method of claim 7 wherein the orifice area has at least about 10 rows in each direction.

10. The method of claim 7, 8,or 9 wherein said gas flow is directed at an angle in the range of approximately from 40°
to 50° to said plate.

11. The method of claim 5, 6, or 7 wherein said gas is a non-reducing gas.

12. The method of claim 5, 6, or 7 wherein the orifice plate is made of a wettable alloy and said gas is air.

13. Apparatus for forming glass fibers comprising:
means for containing a head of molten glass;
an orifice plate, constructed of a heat resistant mater-ial and disposed at the base of said containing means, having orifice plate heating means, said orifice plate having at least four rows of orifices therein and the orifices being spaced in flooding relationship;

means for controlling the temperature of said plate;
means for withdrawing glass fibers from said plate from molten glass at said orifices; and means disposed below said plate for communication with a supply of gas for directing a bulk flow of rapidly moving non-reducing gas upwardly to the orifice area in said plate, said bulk flow being in an amount and at a velocity and angle suffi-cient to provide stable fiber formation and to prevent flooding of molten glass over the orifice area.