US3785791A

US3785791A - Forming unit for fine mineral fibers

Info

Publication number: US3785791A
Application number: US00231347A
Authority: US
Inventors: W Perry
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-03-02
Filing date: 1972-03-02
Publication date: 1974-01-15
Anticipated expiration: 1991-01-15

Abstract

An improved apparatus for the formation of fine fibers from mineral materials, especially glass, in which the molten material feeds continuously into a rotor which is turning at high speed, and discharges by centrifugal force thru multiple orifices arranged in superposed rows in the outer peripheral wall of the rotor in the form of molten filaments, with hot gaseous means to control the temperature of the zone immediately beyond the rotor outer wall and hold it close to the temperature of the molten filaments, and with a secondary outer attenuation zone comprising a high velocity annular gaseous blast for further attenuating the filaments into fine fibers, and with the gaseous blast composed of multiple individual jets spaced closely together, and so angled that the elements of the blast have a component of their velocity tangential to the rotor outer wall, and moving preferably in the same direction as the outer wall movement. The advantage of this combination is that it produces longer and finer fibers, and with less twisting together than is possible with the means used heretofore. Additional objectives are improved means to control the temperatures in the rotor, reduction of rotor windage, and reduction in the amount of power required to compress the medium used for the outer gaseous blast by reason of more efficient blast nozzles.

Description

att I191 1 FORMING UNIT FOR FINE MINERAL FIBERS [76] Inventor: Walter Merton Perry, 76 Locust Hill Rd, Darien, Conn. 06820 [22] Filed: Mar. 2, 1972 [211 Appl. No.: 231,347

Primaryfixgminer gobgLL Lindsay, Jr. A ttorney-Walter Morton Perry 571 T ABSTRACT An improved apparatus for the formation of fine fibers Jan. 15, 1974 from mineral materials, especially glass, in which the molten material feeds continuously into a rotor which is turning at high speed, and discharges by centrifugal force thru multiple orifices arranged in superposed rows in the outer peripheral wall of the rotor in the form of molten filaments, with hot gaseous means to control the temperature of the zone immediately beyond the rotor outer wall and hold it close to the temperature of the molten filaments, and with a secondary outer attenuation zone comprising a high velocity annular gaseous blast for further attenuating the filaments into fine fibers, and with the gaseous blast composed of multiple individual jets spaced closely together, and so angled that the elements of the blast have a component of their velocity tangential to the rotor outer wall, and moving preferably in the same direction as the outer wall movement. The advantage of this combination is that it produces longer and finer fibers, and with less twisting together than is possible with the means used heretofore. Additional objectives are improved means to control the temperatures in the rotor, reduction of rotor windage, and reduction in the amount of power required to compress the medium used for the outer gaseous blast by reason of more efficient blast nozzles.

14 Claims, 11 Drawing Figures PMENTEDJAN 15 1914 SHEEI 2 [IF 2 FORMING UNIT FOR FINE MINERAL FIBERS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the formation of fine fibers from heat softenable mineral materials, more particularly glass, by introducing a stream of the hot softened material into a hollow rotor which is turning at high speed, and which has multiple orifices in its outer peripheral wall thru which the molten material discharges outwardly by centrifugal force to form fibers, and with gaseous means to control the temperatures in the zone immediate to the rotor outer wall, and with additional high velocity gaseous means provided to further attenuate the fibers to substantially decrease their diameters.

The fibers so produced are then generally spray impregnated with a thermo-setting resinous binder and collected on a foraminous conveyor, supplemented with the output of several additional fiberizing units, and with the blanket so formed then sized to thickness and the resin cured in a continuous oven.

2. Description of Prior Art The means and apparatus heretofore used to accomplish the formation of fine fibers by similar rotary process have had several serious drawbacks which prevented attainment of the desired physical properties of the fibers and prevented their proper orientation, and as a result reduced the quality of the end products into which the fibers were formed. For instance, the means used up to now have resulted in the fibers being too coarse and non-uniform in size, relatively short in length, and excessively twisted and balled up. If the fibers are too short they are less likely to lie horizontally in the formed blanket, and instead a large number will stand inclined or on end, in which position heat is conducted along the body of the fiber and thru the thickness of the insulating mat, reducing its insulating value. Coarse fibers also transfer more heat because of their larger size. Excessive twisting and balling up of the fibers produces porous spots in the blanket, which also results in 'a higher thermal conductivity, or k value for the insulation. The k value is defined as the amount of heat expressed in Btus transmitted in l hour thru one square foot of a homogeneous material 1 inch thick for a difference in temperature of one degree Fahrenheit between the two surfaces of the material. Short fibers and poor orientation also make a weaker sheet in products requiring tensile strength and rigidity. Among the more common products manufactured by this rotary process are insulation mats and blankets, sound absorbing panels, sheets for air ducts, and chopped fibers for plastic reinforcement.

Major draw-backs in the apparatus used up to now in the centrifugal fiber forming process have been due to excessive and uneven heat loss from the rotor by radiation, by windage, and by conduction to the cooled driving shaft, and by uneven replacement of this heat to maintain the glass at its optimum attenuating temperature, and also to non-uniform or excessive temperatures and velocities in the zone immediately adjacent to the outer wall of the rotor where the filaments are first formed, and also and primarily to lack of proper directional control of the final gaseous attenuation blast with respect to the direction of rotation of the rotor outer wall.

BRIEF SUMMARY OFTHE INVENTION It is a primary object of the invention to produce fine fibers which are more uniform in size and of substantially greater length than ispossible with apparatus known before. Another primary objective is to minimize the tendency of the fibers to twist together such that they form a blanket which is not uniform in density thru-out its thickness and length.

A primary objective of the invention is to provide means for controlling the direction of the gaseous flow in the outer annular attenuation blast, this controlled angular direction being with respect to the direction of movement of the outer wall of the rotor, to which the outer gaseous flow is maintained partially tangential.

A further object of the invention is to construct the discharge tubular orifices which comprise the outer annular blast means in such a manner that conversion of gaseous pressure to velocity is more efficient, effecting a saving in power required to compress the gas and also serving to increase the effective velocity and kinetic energy in the blast. A further object of the invention is to provide more than one outer annular blast.

Still another object of the invention is to hold the gaseous flame which maintains the temperature in the initial attenuation zone just beyond and adjacent to the outer perforated wall of the rotor at a uniform level just above the glass filament temperature and free of uncontrolled cool infiltrated air, and this same flame serving to help hold the perforated wall temperature just above that of the glass.

Another object of the invention is to optionally control the angular direction of the annular flame discharged from the burner exit slot serving the first attenuation' zone so it moves in a direction partially tangential to that of the rotor outerwall.

Still another object of the invention is to maintain the temperature of the flanged parts of the rotor adjacent to the outer wall by a separate heat source so these parts do not draw heat from the perforated wall.

A further object of the invention is to construct the rotor with its perforated outer wall and its glass receiving inner disc independent of its shaft mounted supporting flange, and with light-weight insulation between the two parts. This reduces heat loss from the rotor disc which receives the stream of molten glass, so heat make-up to maintain the required temperature comes largely from the incoming molten material.

A further object of the invention is to partially insulate the lower rotor supporting flange from the shaft in order to reduce still further the loss of heat to the water cooled rotor shaft.

Another object of the invention is to form the rotor flange elements in such a way as to reduce windage, which both causes a loss in temperature of parts of the rotor and also entangles the fibers in the first attenuation zone, which is just as the filaments leave the rotor outer wall.

BRIEF DESCRIPTION OF THE DRAWINGS ings:

FIG. 1 is a vertical sectional view thru the part of the apparatus forming the subject matter of this invention.

FIG. 2 is a cross-sectional view of part of the outer annular blast means showing the angular positioning,

and is taken on line 2-2 of FIG. 1.

FIG. 3 is a horizontal sectional view taken on line 33 of FIG. 2, and shows the adjacent positioning of the individual blast nozzles.

FIG. 4 is a sectional view similar to FIG. 3, but showing an alternative positioning of the lower ends of the tubular nozzles.

FIG. 5 is a sectional view taken on line 5-5 of FIG. I, showing the construction of the tangential burner elements which make up the main burner assembly for control of the temperatures and gas currents adjacent to the outer wall of the rotor.

FIG. 6 is a side view of the forming unit assembly which shows the angular and partially tangential paths of the gaseous elements in the outer annular blast with respect to the direction of rotation of the rotor, and with the blast elements moving with a velocity component in the same direction as the rotor outer wall.

FIG. 7 is similar to FIG. 6, but with the outer blast elements moving vertically and parallel to the axis of the rotor, as an optional but less desirable arrangement.

FIG. 8 is also similar to FIG. 6, but with the outer blast elements moving with the tangential component of velocity moving against the direction of the rotor wall, which is a less desirable arrangement.

FIG. 9 is a vertical sectional view of an alternative design which incorporates some of the main features of the invention, and also shows two outer annular attenuation blasts.

FIG. 10 is a cross-sectional view of part of the outer annular blast means similar to FIG. 2, but showing an alternative method of construction.

FIG. 11 is a horizontal sectional view taken on line 11-11 of FIG. 10 to further explain the construction method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION The present invention provides improved apparatus for forming fine fibers from heat softenable materials, most importantly glass. The glass must be first melted to a fluid state above its liquidus temperature. This may be accomplished by melting cullet or or marbles in a retort, pot, or bushing. The most usual and efficient method, however, is to position the fiber forming apparatus under the forehearth at the finishing end of the glass making furnace, and to discharge the melted glass directly into the fiberizing unit at the correct temperature. The most usual practise is to provide several fiberizing units, each receiving a glass stream from the forehearth, and generally arranged in line, one after the other.

FIG. I shows the arrangement of the fiber forming apparatus which incorporates the novel features of this invention. Additional equipment is also required beyond this unit, such as spray means for applying resinous binder to the fibers, a foraminous collection conveyor under the fiber forming unit on which the fibers are collected with suction means under the conveyor to draw down the fibers into mat form, and an oven for sizing and curing the resin impregnated mat, but these are not shown as such equipment is well known in the art.

Referring now to FIG. 1 of the drawings, a section of the forehearth of the glass making furnace is shown at 14. A stream of molten glass 12 discharges from orifice 13 in the bottom of the forehearth. The rate of flow and the temperature of the glass are closely controlled. A water cooled compartment 15, is located under the 5 forehearth to protect the driving unit from excess heat. A supplemental vertical section 18 serves to absorb the radiation from the glass stream 12. The cooling water enters at 16 and discharges at 17 for the two sections.

The stream of glass discharges continuously into rotor 45. This rotor is mounted on shaft 20 and is rotated at high speed. The speed ranges from 2,000 to 4,000 RPM, depending on the diameter of the rotor, which customarily ranges from 6 inches to 12 inches. 5 Whereas the spinner is shown with a vertical shaft, it may be inclined or horizontal in accordance with prior art, provided suitable changes be made in means to introduce the glass stream into the rotor.

The rotor shaft may be driven by electric motor, preferably mounted to one side as shown, with pulley 27 on the motor shaft which drives belt 26 engaging pulley on shaft 20. Shaft 20 is mounted on

ball bearings

21 and 22 which are positioned in sleeve 23, which in turn is supported on the main frame, not shown. The sleeve is cooled by spiral water piping 24. Cooling means are also provided for shaft 20, and include water supply pipe 28 at the top, innertube member 29 thru which the water flows downward and out thru hole 34 into the cavity between the tube 29 and the wall of the shaft. The cooling water rises and discharges thru nozzle 31 into collecting chamber 32 and then out drain 33. The rotor design has several novel features in keeping with this invention. Heretofore the rotors have been connected to the cooled mounting shaft in such a way as 35 to draw excessive heat from the rotor, and this heat is difficult to replace while still maintaining a uniform temperature thru-out the inner working areas of the rotor, where the temperature of the glass must be maintained above its liquidus temperature and close to its optimum working range.

In keeping with my invention, the rotor is constructed with a hollow shaped bottom flange 42 which supports the main section of the rotor, and serves to drive it. Member 42 is mounted on insulating collar 39, which is made of hard machinable refractory insulation, and serves to reduce the heat flow to shaft 20. It is held by nut 40. The contour of flange 42 is designed with an outer curved edge 43 curving downward as shown. I have found that a hollow disc of this design with its cup shaped outer peripheral section can be rotated at high speed without forming any appreciable wind currents on its hollow underside. This compares with the usual convex shaped bottom heretofore used, and which results in the formation of excessive windage. Such wmdage heretofore served to cool the rotor body on its underside, especially at the outer wall, and also adversely affected the fiber formation by causing balling up of the fibers.

The main body of the rotor is 45 with outer wall 46, and with several thousand small orifices 47 arranged in superposed rows in the outer wall thru which the molten glass flows to form molten filaments 49 under the pressure of centrifugal force due to the rotation of the rotor assembly. Member 45 may be of precious metal, such as an alloy of platinum and rhodium, or it may be made of one of the many high temperature base metal alloys now available, and containing varying percentages of nickel, iron, chromium, molybdenum, and other elements. These alloys are marketed under the trade-names of lnconel, I-lastelloy, Nichrome, Nimonic, Duranickel, and numbered stainless steels. Lower flange 42 may be made of one of these high temperature base metalalloys, and may be attached to 45 by welding, or preferably using a circle of nickel alloy rivets 44. This construction minimizes the flow of heat from the rotor part 45 to the shaft, both because of the small metallic contact and because high temperature nickel alloys are poor heat conductors. Member 45 has an inner formed section 50 of the approximate shape shown, and preferably with a shoulder at 51. Shoulder 51 is roughly in line with the center of the band of perforations in the rotor outer wall. Glass stream 12 falls onto rotating surface 50 and the glass flows down the incline to the shoulder 51, whence it is thrown out by centrifugal force to the inner side of wall 46, providing uniform distribution within the limits required. Some glass can flow down the incline below 51 to the lower region of the outer wall. A low density insulation 52 is provided to reduce the loss of heat downward from section 50. It may preferably be 'of fibrous type, and extend down between 42 and 45 at the rivet line.

The upper flange 53 of the rotor also has a reverse bend, both to reduce windage, and further to facilitate heating by a single burner 37 located above the rotor and 180 from the glass stream. This burner is supplied with air-gas mixture thru pipe 38, and its flame is directed to heat all surfaces 46, 50, and 53. The flame of this burner has a considerably higher temperature than that of burner 60 in order to effect'more rapid heat transfer so a single burner is sufficient. The flame temperature of 37 may be 3,000 to 3,300 F.

The usual glasses used in this type of operation have an optimum fluidity for centrifugal ejection at temperav tures ranging from l,900 to 2,l F. The glass is held at a somewhat higher temperature in stream 12 to compensate for a small temperature drop before it passes thru the perforations. The heat from this temperature drop helps to hold member 50 close to the glass temperature, but some additional heat is added to 50 byburner 37. Prior art shows the same burner for heating the rotor flanges as for heating the initial attenuation zone 48, and since to effectively transfer heat to the flanges requires a higher flame temperature than is permissable in zone 48, such prior art depends on infiltrated air to partially cool the flame to the 1,900 to 2,l00 F. required in zone 48. his impossible to mix high temperature flame with cool infiltrated'air in such a small and confined area and obtain uniform temperatures at all points.

Referring still to FIG. 1, a burner assembly 60 is provided to produce a hot gaseous flame 70 to maintain zone 48 at close to the glass filament temperature, which ranges from l,900 to 2,l00 F., depending on the glass composition being used. Flame 70 is preferably of relatively low velocity because the attenuation of filaments 49 into very fine fibers is to be accomplished primarily by gaseous blast 81. It is advantageous that flame 70 discharge from the annular burner exit slot with a component of its velocity in a direction tangential to the rotor outer wall, and moving in the same direction. This is accomplished by the burner design shown in FIG. I, and in the sectional view of FIG. 5, in which the section is alongline 5 of FIG. 1.

Burner 60 is constructed with multiple burner tunnel assemblies similar to that shown in FIG. 5 arranged around its circumference. Four or six tunnels is the preferred arrangement to obtain uniform exit velocities and temperatures. Referring to FIG. 1, air-gas mixture The air-gas mixture passes thru ceramic screen 63a,

and shoulder 64a becomes incandescent to maintain combustion. The combustion is generally complete within refractory tunnel 59a before the gases reach the main burner annular chamber defined by outer refractory wall 66a and inner refractory wall 65a. A lean airgas mixture is used in order to hold the flame temperature down as close as possible to the exit temperature desired at the rotor wall. It is generally necessary to add additional cooling air, and this is accomplished thru pipe connection 54a, which discharges airinto the tunnel 59a where it mixes with the hot gases. A compressed air annular header 56d supplies the cooling air, and orifice 55a regulates the amount to this burner, and with over-all control by varying the pressure in the header. By introducing the cooling air at this point it is thoroughly diffused by the time the flame exists at 70, so the temperature at is very uniform.

In FIG. I. the tangential burner is 57, the ceramic screen is 63 with incandescent circular shoulder 64, and the tangential burner tunnel wall is 58. The main annular burner refractory walls are 65 and 66, and

these converge downward to where the annular exit slot is defined by

stainless steel walls

67 and 68, cooled by water tubes 69. Optionally annular wall 68 has inclined thin spaced fins 73, and wail 67 has similar but staggered inclined fins 72, these fins helping to control the tangential component of the flame. The tangential arrangement of the burners 57 serves to rotate the hot gases in the main tunnel and to also give the exit gases at 70 a tangential velocity component preferably in the direction of the movement of the rotor outer wall.

In FIG. I the flame 70 also assists in holding outer wall 46 at the temperature of the glass flowing thru the perforations. Further it supplies the gases for the windage created by the high velocity of wall 46, so the windage does not cool the wall. Further, flame 70 provides the hot gases which are drawn down by the inspirational effect of high velocity blast 8i, described below. Otherwise-cool room air would be inspirated, cooling the rotor. It is important to note that flame 70 is relatively low in velocity, and is used for temperature control and not for substantially attenuating the filaments. The diameter of the filaments as they leave the rotor wall is on the order of 10 microns, or 0.0004 inch.

Final attenuation of the filaments to the finished size is effected by high velocity annular gaseous blast 81. The fineness desired depends on the product being manufactured, and it will vary normally over a range of 2% to 5 microns, with 4 microns satisfactory for most insulations. The blast is preferably warm air, but may be hot air, cool air, steam, or other gas. The blast should be as close to the wall 46 of the rotor as convenient without resulting in cooling of the wall. If too far away the fibers become entangled excessively.

The most important element of this invention is the manner in which the outer gaseous blast is formed, and the guided direction in which it moves. Referring to FIG. I, an annular header 75, with removable cover 76, is supplied with filtered compressed air, or other gaseous medium, thru supply pipe 83. In the most desireable form the gas is air.

In order to obtain the most efficient conversion of gaseous pressure to gaseous velocity and kinetic energy, in accordance with this invention the annular outer blast is discharged thru a series of tubular nozzles designed for maximum efficiency from the aerodynamic standpoint. One of these nozzles 77 is shown in FIG. I, and the next adjacent one is 79. It will be noted that each tube is flared out at the upper inner end and every other nozzle is slightly longer and bent sufficiently so the flared ends do not interfere to prevent close spacing of the lower ends of the nozzles around the circumference.

FIG. 2 shows a cross-section thru several nozzles taken along line 2-2 in FIG. 1. In FIG. 2 are shown four

adjacent nozzles

77a, 79a, 91a, and 92a. Each nozzle has an upperflared end to provide sufficient metal at the entrance of the passageway so the entrance can be formed to the exact shape required to attain maximum entrance efficiency with the least turbulance, as well known in the art of air flow. The entrance for nozzle 77a is 78a and for 79a is 80a. For greatest aerodynamic efficiency the outer diameter of the flare at 78a should be twice the inside diameter of the nozzle tubular section.

The most important feature of the air blast design is the angle at which the nozzles are set. This angle is 95a in FIG. 2. In order to obtain the longest fibers and with the least intertwining of fibers, the nozzles and the blast should be arranged with the angular discharge pointing in the same direction as the rotation of the part of the rotor face nearest the nozzle. In other words the blast has a component of its velocity which is tangential to the rotor wall movement, and in the same direction.

I have found that this nozzle arrangement provides a major improvement in the rotary process, giving longer fibers, more uniform fibers, and with less balling up. This makes possible the production of insulation products at a lower density than theretofore, and still maintaining the same insulating value. Or the same density can be produced, but with better insulating properties, or lower heat conductivity. Also'the longer fibers and better orientation produces mats having greater tensile strength.

The positioning of the lower or discharge ends of the nozzles is shown in FIG. 3, and is a section taken along line 33 in FIG. 2. It will be noted that the ends are close together, and are 92b, 91b, 79b, and 77b respectively for the four nozzles illustrated. FIG. 4 shows a similar cross-section, but with the nozzles staggered, bringing the inner passages closer together. The nozzles are 92c, 91c, 79c, and 77c respectively. The preferred material for construction of the nozzles is stainless steel. This provides a smooth surface that gives low resistance to air flow, and assists in laminar flow being obtained for highest possible jet velocity. It also prevents the surface from becoming rough from oxidation. The tubular length of the nozzles, beyond the flare, should not be any longer than necessary. A length of several pipe diameters is sufficient for most efficient flow and directional guidance of the jet. The

lengths shown on the drawing are greater in order to clarify the arrangement.

Each nozzle should also have its lower discharge end set at the most advantageous angle with respect to the nearest vertical wall or outer face of the rotor. This angle is shown at 82 in FIG. I, and it has been found that for best operation the nozzle lower end and the discharging jet should point somewhat toward the rotor face as shown in the drawing. In other words the outer gaseous blast is slightly conical, converging downward, rather than cylindrical, and also in accordance with the primary objective of this invention, the gaseous elements also move in a rotational or spiral direction, preferably in the direction of rotation of the rotor. Whereas I show the rotor with a vertical outer face, this face can also be somewhat inclined in accordance with prior art, and the angle of the nozzles adjusted accordingly.

A circular baffle member 84 in FIG. 1 is provided to enclose the attenuation zone to reduce inspiration of ambient air from the outside. A shield 71 also limits inspiration of air from above, and an opening 74 is provided for passage of the glass stream 12.

The angular discharge of the outer gaseous blast is further illustrated in FIGS. 6, 7, and 8. Referring to FIG. 6, this shows a side view of the fiber forming as sembly with rotor I11 turning on shaft 110, burner housing 116, and gaseous header 112, where the view is broken away to show the gaseous blast nozzles II3 inclined at an angle so the gaseous blast elements 114 discharge at an angle with respect to the axis of the shaft, or the vertical. The near side of the rotor is moving to the right in the direction of the arrow.

This is the preferred angular setting of the outer gaseous jets to obtain the finest and longest fibers. Optionally, however, the unit can be designed with the jet discharge vertical, and parallel to the shaft, as shown in FIG. 7, in which the shaft is 110a, the rotor Illa, the burner 116a, the gaseous supply header 112a, and the broken away view shows the blast nozzles 113a positioned vertically and with the gaseous blast 114a moving straight down. For some operations requiring shorter fibers the jets can be designed with a reverse angle as shown in FIG. 8, in which the shaft is 110b, the rotor 111b, the burner I 16b, the gaseous supply header 112b, and the jet nozzles 113b angled backward, and with the gaseous blast discharging at reverse angle I 15b against the direction of rotation of the rotor outer wall.

FIG. 9 shows a modified form of my invention. The glass stream 124 falls directly onto inner member 125 of rotor I31, and is carried by centrifugal force to the outer wall 136 of the rotor, whence the glass is carried thru orifices 137 by centrifugal force to form filaments 138. Rotor body 131 is supported on hollow bottom plate I32 to which it is attached by circle of rivets I23, and plate 132 has outer curved down edge 122. Insulation 133 and insulating bushing 134 serve to reduce the heat loss from the rotor 131. Nut 135 holds the assembly to the shaft 130. Burner 139 provides an annular discharge of hot gases 140 to control the temperature in the initial attenuation zone adjacent the rotor wall 136 close to the l,900 to 2,l00 F. range required to sustain the temperature of the discharging filaments.

Annular header I44 supplies compressed gaseous medium, such as compressed air, to an initial circle of nozzles 146, which discharge attenuation blast to attenuate the filaments into fine fibers. A second circle of nozzles I53 is also provided, and with the lower ends of these nozzles protected by annular shroud I48. This row of nozzles discharge attenuation blast. ISI, and theyare backed up by shroud 154 to reduce air infiltration. The double circle of nozzles makes it possible to attenuate efficiently with a rotor wall of greater height with more rows of orifices for greater output.

The individual nozzles in each circle of the outer gaseous blast should preferably be angled in the direction of rotation of the rotor, so the high velocity blast has a velocity component which is tangential to the rotor outer wall and moving in the same direction, in keeping with the primary objective of my invention.

The blast nozzles with flared entrance ends will have a velocity coefficient, or efficiency, as high as 0.96, thus substantially increasing the exit velocity for a given header pressure over that obtainable with the sharp edged annular slots used heretofore. This permits using lower header pressures, and enables the attainment of the required high velocity blast with pressures between 3 and IS pounds per square inch gage. This reduction in pressure decreases the horsepower required to compress the air or other gaseous medium by as much as 30 percent. The preferred gaseous medium is warm air, and because of its relatively high density, added to its high velocity, it provides high kinetic energy for attenuating the filaments into fine fibers.

FIG. 10 shows an alternative,v but less efficient method for constructing the nozzle elements. A circular annular member 102 has formed across its face a series of ridges I03 set at angle 104. FIG. II is a crosssection taken along line II-1I of FIG. I0, and shows outer cover facing 106a to form the spaces between the ridges into discharge slots or nozzles. This construction is less efficient aerodynamically because the entrance ends of the slots can not be flared properly, although the upper edges can be formed with a radius.

In FIG. 9 three separate burners are provided to control the temperatures in the different parts of the rotor. Burner I64} with air-gas mixture supply pipe I61 heats the upper flange I41 of the rotor, burner I65 with supply pipe 162 heats member 125, and burner I66 with supply pipe I63 heats the rotor outer wall I38 from the inside, and also adds heat to the glass at this point. By providing individually controlled burners for the three elemental parts of the rotor it is possible to hold the temperature of each part close to the desired temperature of the glass at that point. Thermo-couples may be used to control each flame for increased accuracy. Whereas the drawing shows a single burner for each element, two or more burners may be arranged in parallel around the circumference.

Referring to FIG. I it will be noted that the gaseous blast 81 is shown moving down at an angle 82 with the vertical, or with the axis of the rotor. This angle is shown to an exaggerated scale in the drawings for clarity. In the ensuing claims I describe this slightly conical direction of flow as a component of velocity that is substantially parallel to the axis of the rotor in order to more clearly differentiate it from the tangential component of velocity. Each individual gaseous element has a major velocity component which is downward and in the same plane as the axis of the rotor, and which is substantially parallel to the rotor axis, even though the combined downward gaseous velocity components are slightly conical.

The tangential component of velocity of the gaseous elements in the outer blast is in a plane which is perpendicular to the axis of rotation of the centrifugal rotor and substantially tangential to it.

In an alternative arrangement, a second annular outer gaseous blast is provided, and is positioned radially outward from the first annular blast nozzle assembly, and mounted further down in the direction of the blast, and just below the bottom of the rotor. The nozzles are angled so this blast has a velocity component tangential to the rotor outer wall, but discharging in a direction against the direction of-rotation of the rotor wall. It is also thereby against the tangential component of the first outer annular blast. The second blast has a much lower velocity, and its purpose is to counteract the spiral motion of the falling fibers, and cause them to fall instead straight down to the collection conveyor, eliminating any centrifugal tendency to spread the cone of fibers.

This arrangement with two annular rings of blast nozzles is quite similar to that shown in FIG. 9, except that annular shroud 143 extends down close to the level of the lower edge of rotor I31, and ring of nozzles 153 is also positioned lower down so its blast 151 starts at the lower edge of shroud I48 in its lower position. Also a separate supply header is required for these nozzles as the blast is of considerably lower velocity. The lower blast in this arrangement has a tangential velocity component against the direction of movement of the rotor outer wall.

Where previous reference is made to air-gas mixture for burners, it is to be understood that gas refers to any combustible ga s, preferably natural gas (methane), or

propane. Further, the heating method used for the rotor parts and for the initial attenuation zone just beyond the rotor outer wall, and used in conjunction with the direction oriented outer gaseous blast, is not necessarily restricted to gas burners. The heating may be accomplished by, or supplemented by, electric or gas radiant heat, high frequency induction heating, or oil burner flame.

FIG. 9 also illustrates the usual way to apply thermosetting phenolic binder to the glass fibers as they are formed. A circular shroud I guides the fibers as they pass down to the foraminous collection conveyor. A ring of atomizing guns serves to apply the binder to the fibers, and one of these guns I71 is illustrated. The binder solution is-supplied from a header tl'iru pipe connection I72, and compressed air is similarly supplied thru connection 173 for atomizing the solution.

It will be apparent that while I have shown and described the invention in several preferred forms, changes may be made without departing from the scope of the invention, as sought to be defined in the following claims.

What I claim is:

1. In an apparatus of the character disclosed for forming fine fibers from heat softenable viscous thermo-plastic mineral material, such asglass, said apparatus comprising:

a hollow rotor, the outer peripheral wall of which has a plurality of superposed filament forming orifices therein, shaft means for supporting the rotor, and means for turning the rotor at high speed to effect discharge of the mineral material thru the orifices by centrifugal force, and in the form of filaments,

means for supplying said heat softened mineral material to said rotar,

means for controlling the temperature of parts of the rotor,

means for supplying an annular heat source for the initial attenuation zone contiguous to the outer peripheral rotor wall, and with means to maintain the temperature of the exiting filaments close to the temperature at which they discharge from the rotor,

an annular gaseous supply manifold connected to annular orifice means, and said orifice means positioned concentrically to and radially outward from the rotor outer wall, and with said orifice means serving to discharge a high velocity annular blast directed into engagement with said filaments to further attenuate the filaments into fine fibers,

the improvement comprising angular gaseous blast guidance means whereby the gaseous elements in said high velocity annular gaseous blast are so directed as to have two principle velocity components, with one velocity component in the same plane as the axis of said rotor and moving in a direction substantially parallel to said axis, and the second velocity component moving in a direction which is substantially tangent to the circular outer wall of said rotor, and with said blast being directed in proximity to and spaced outwardly from the outer wall of said rotor.

2. In an apparatus of the character disclosed for forming fine fibers from heat softenable viscous thermo-plastic mineral material, such as glass, said apparatus comprising:

means for supplying said heat softened mineral material to said rotor,

means for controlling the temperature of parts of the rotor,

means for supplying an annular heat source for the initial attenuation zone contiguous to the outer peripheral rotor wall, and with means to maintain the temperature of the exiting filaments close to the temperature at which they discharge from the rotOl',

the improvement comprising a plurality of individual nozzle means arranged in spaced annular ring-like array with said nozzle means connected to gas supply manifold, and thru which nozzle means gases discharge at high velocity to form said gaseous blast, and wherein said nozzle means have an angular setting whereby the increments of the blast have two principle velocity components, and with one velocity component in the same plane as the axis of said rotor and moving in a direction substantially parallel to the axis of said rotor, and the second velocity component moving in a direction substantially tangent to the circular outer wall of said rotor and moving in the same direction that the outer wall rotates, said nozzle means being directed in proximity to and spaced outwardly from the outer wall of said rotor.

3. Apparatus according to claim 1 in which said high velocity annular blast is air.

4. Apparatus according to claim 2 in which said individual nozzle means are positioned close together in annular concentric array, and serving to give a practically continuous gaseous blast. 7 5. Apparatus according to claim 2 in which said individual nozzle means comprise tubular nozzle members, and in which the entrance ends of the nozzle members for receiving the header gases are flared outward to give stream line flow thru the nozzles and to increase the coefficient of discharge from the nozzles.

6. Apparatus according to claim 2 in which the means for supplying an annular heat source for the initial attenuation zone contiguous to the outer peripheral wall of said rotor comprises an annular gaseous heat source discharging hot gases into said initial attenuation zone, and with means for controlling the temperature and the velocity and the direction of flow of said gaseous heat supply means.

A i A ppa ratu s according to claim 6 in which said means for controlling the temperature and the velocity and the direction of flow of said gaseous heat supply means provides hot gases discharging into the initial attenuation zone contiguous to said rotor outer wall which have relatively low velocity, and have a temperature range from 1,900 F. to 2,400 F. to suit the composition of the mineral material being fiberized.

8 Apparatus according to claim 6 in which said means for controlling the temperature and the velocity and the direction of flow of said gaseous supply means discharges hot gases into the initial attenuation zone contiguous to said rotor outer wall, and wherein increments of the hot gases have two principle velocity components, with one of the velocity components moving tangentially to the circular outer wall of said rotor and in the same direction that the outer wall rotates, and the other velocity component in the same plane as the axis of said rotor and moving in a direction substantially parallel to the axis of said rotor.

I 9. Apparatus according to claim 8 in which the means to control the direction of discharge of said hot gases comprises an annular combustion chamber exit slot having angled fin members positioned on the inner walls of said exit slot.

10. Apparatus according to claim 1 in which means for supplying an annular heat source for said initial attenuation zone comprises an annular gaseous heat source discharging hot gases into said initial attenuation zone contiguous to said rotor outer wall, means for controlling the temperature and the velocity and the direction of said hot gases, and wherein the increments of the hot gases have two principle velocity components, with one of the velocity components moving substantially tangent to the circular outer rotor wall and in the same direction that the wall rotates, and the other velocity component in the same plane as the axis of said rotor and moving in a direction substantially parallel to the axis of the rotor and to the outer gaseous blast.

11. Apparatus according to claim 2 inwhich there is a plurality of gas supplied ring-like arrays of nozzle means, and wherein each additional ring of nozzle means is positioned radially outward from the previous ring, and positioned further downstream in the direction of the blast.

12. Apparatus according to claim 1 in which said angular gaseous blast guidance means directs the gaseous blast so it has two principle velocity components, with one velocity component in the same plane as the axis of said rotor and moving in a direction sustantially parallel to said axis, and the second' velocity component moving in a direction which is substantially tangent to the circular outer wall of said rotor, and moving in the direction which is opposite tothat of the outer wall of said rotor.

13. Apparatus according to claim 1 in which said angular gaseous blast guidance means directs the gaseous blast elements so they have two principle velocity components, with one velocity component in the same plane as the axis of said rotor and moving in a direction substantially parallel to said axis, and the second velocity component moving in a direction which is substantially tangent to the circular outer wall of said rotor, and moving in the same direction that the outer wall rotates.

14. Apparatus according to claim 2 in which there is a second annular ring-like array of nozzle means, and with said second nozzle means connected to gas supply manifold, and thru which-said second nozzle means gases discharge at substantial velocity to form a forcible gaseous discharge, and wherein said second nozzle means have an angular setting whereby the increments of the gaseous discharge from said second nozzle means have two principle velocity components, and with one velocity component in the same plane as the axis of said rotor and moving in a direction substantially parallel to the axis of said rotor, and the second velocity component moving in a direction substantially tangent to the circular outer wall of said rotor and moving in the direction which is opposite to that of the outer wall of said rotor.

Claims

1. In an apparatus of the character disclosed for forming fine fibers from heat softenable viscous thermo-plastic mineral material, such as glass, said apparatus comprising: a hollow rotor, the outer peripheral wall of which has a plurality of superposed filament forming orifices therein, shaft means for supporting the rotor, and means for turning the rotor at high speed to effect discharge of the mineral material thru the orifices by centrifugal force, and in the form of filaments, means for supplying said heat softened mineral material to said rotor, means for controlling the temperature of parts of the rotor, means for supplying an annular heat source for the initial attenuation zone contiguous to the outer peripheral rotor wall, and with means to maintain the temperature of the exiting filaments close to the temperature at which they discharge from the rotor, an annular gaseous supply manifold connected to annular orifice means, and said orifice means positioned concentrically to and radially outward from the rotor outer wall, and with said orifice means serving to discharge a high velocity annular blast directed into engagement with said filaments to further attenuate the filaments into fine fibers, the improvement comprising angular gaseous blast guidance means whereby the gaseous elements in said high velocity annular gaseous blast are so directed as to have two principle velocity components, with one velocity component in the same plane as the axis of said rotor and moving in a direction substantially parallel to said axis, and the second velocity component moving in a direction which is substantially tangent to the circular outer wall of said rotor, and with said blast being directed in proximity to and spaced outwardly from the outer wall of said rotor.

2. In an apparatus of the character disclosed for forming fine fibers from heat softenable viscous thermo-plastic mineral material, such as glass, said apparatus comprising: a hollow rotor, the outer peripheral wall of which has a plurality of superposed filament forming orifices therein, shaft means for supporting the rotor, and means for turning the rotor at high speed to effect discharge of the mineral material thru the orifices by centrifugal force, and in the form of filaments, means for supplying said heat softened mineral material to said rotor, means for controlling the temperature of parts of the rotor, means for supplying an annular heat source for the initial attenuation zone contiguous to the outer peripheral rotor wall, and with means to maintain the temperature of the exiting filaments close to the temperature at which they discharge from the rotor, an annular gaseous supply manifold connected to annular orifice means, and said orifice means positioned concentrically to and radially outward from the rotor outer wall, and with said orifice means serving to discharge a high velocity annular blast directed into engagement with said filaments to further attenuate the filaments into fine fibers, the improvement comprising a plurality of individual nozzle means arranged in spaced annular ring-like array with said nozzle means connected to gas supply manifold, and thru which nozzle means gases discharge at high velocity to form said gaseous blast, and wherein said nozzle means have an angular setting whereby the increments of the blast have two principle velocity components, and with one velocity component in the same plane as the axis of said rotor and moving in a direction substAntially parallel to the axis of said rotor, and the second velocity component moving in a direction substantially tangent to the circular outer wall of said rotor and moving in the same direction that the outer wall rotates, said nozzle means being directed in proximity to and spaced outwardly from the outer wall of said rotor.

4. Apparatus according to claim 2 in which said individual nozzle means are positioned close together in annular concentric array, and serving to give a practically continuous gaseous blast.

5. Apparatus according to claim 2 in which said individual nozzle means comprise tubular nozzle members, and in which the entrance ends of the nozzle members for receiving the header gases are flared outward to give stream line flow thru the nozzles and to increase the coefficient of discharge from the nozzles.

7. Apparatus according to claim 6 in which said means for controlling the temperature and the velocity and the direction of flow of said gaseous heat supply means provides hot gases discharging into the initial attenuation zone contiguous to said rotor outer wall which have relatively low velocity, and have a temperature range from 1,900* F. to 2,400* F. to suit the composition of the mineral material being fiberized.

8. Apparatus according to claim 6 in which said means for controlling the temperature and the velocity and the direction of flow of said gaseous supply means discharges hot gases into the initial attenuation zone contiguous to said rotor outer wall, and wherein increments of the hot gases have two principle velocity components, with one of the velocity components moving tangentially to the circular outer wall of said rotor and in the same direction that the outer wall rotates, and the other velocity component in the same plane as the axis of said rotor and moving in a direction substantially parallel to the axis of said rotor.

9. Apparatus according to claim 8 in which the means to control the direction of discharge of said hot gases comprises an annular combustion chamber exit slot having angled fin members positioned on the inner walls of said exit slot.

11. Apparatus according to claim 2 in which there is a plurality of gas supplied ring-like arrays of nozzle means, and wherein each additional ring of nozzle means is positioned radially outward from the previous ring, and positioned further downstream in the direction of the blast.

12. Apparatus according to claim 1 in which said angular gaseous blast guidance means directs the gaseous blast so it has two principle velocity components, with one velocity component in the same plane as the axis of said rotor and moving in a direction sustantially parallel to said axis, and the second velocity component moving in a directIon which is substantially tangent to the circular outer wall of said rotor, and moving in the direction which is opposite to that of the outer wall of said rotor.

14. Apparatus according to claim 2 in which there is a second annular ring-like array of nozzle means, and with said second nozzle means connected to gas supply manifold, and thru which said second nozzle means gases discharge at substantial velocity to form a forcible gaseous discharge, and wherein said second nozzle means have an angular setting whereby the increments of the gaseous discharge from said second nozzle means have two principle velocity components, and with one velocity component in the same plane as the axis of said rotor and moving in a direction substantially parallel to the axis of said rotor, and the second velocity component moving in a direction substantially tangent to the circular outer wall of said rotor and moving in the direction which is opposite to that of the outer wall of said rotor.