JP2002524381A - Cooling air delivery system to tapered glass fiber area - Google Patents

Abstract

(57) Abstract: A method and apparatus 10 for forming a continuous glass fiber. The method includes providing a plurality of streams of molten glass 16 from a bushing 14, withdrawing the plurality of streams into a plurality of continuous glass filaments 20, and an amount determined by the speed at which the glass filaments 20 are withdrawn. Providing a stream of one cooling air 12 parallel to the direction of withdrawal of the plurality of continuous glass filaments 20 to at least the front and rear surfaces of the bushing 14 so that the cooling air 12 is entrained, and Collecting a suitable filament 20. A device for distributing the impervious cooling air 12 to the tapered region of the glass withdrawal process of the bushing 14 comprising one bushing tip plate 14 having a plurality of bushing tips 18 is selected by pressure to a plurality of outlets 30. It has at least two chambers 28 including an inlet 28 to which cooling air 12 is supplied at a constant flow rate. The outlet 30 extends a length in the longitudinal direction of the bushing chip plate 14, thereby providing cooling air 12 to the front and rear surfaces of the chip plate 14. The entrainment of cooling air 12 is a function of the speed at which glass filament 20 is withdrawn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a glass fiber taper of a process of mechanically drawing a glass fiber.
a distribution system for delivering cooling air to an (attenuation) area. More specifically, the present invention provides a non-intrusive
A method and apparatus for delivering cooling air, wherein the flow of cooling air in the process is dependent on the speed at which the glass filaments are withdrawn. The movement of the fiber creates a local vacuum, causing a nominal velocity of air flow, whereby the glass fiber entrains the required cooling air without changing the diameter of the fiber. can do. This device provides the required supply of cooling air at least on the front and rear of the bushings used to extract the glass, preferably around the entire circumference of the chip plate.

[0002]

[Prior art]

The present invention relates to the formation of glass filaments, and more particularly to an apparatus for providing a uniform thermal environment in a tapered region below a plurality of orificed filament forming tips on a heated glass fiber forming bushing and About the method.

[0003] It is well known in the art to make a plurality of filaments from glass by flowing molten material from a plurality of orifice tips mounted on the bottom of a heated bushing. Their streams are usually tapered to the filaments by mechanical means. The plurality of filaments are collected into a twisted yarn, which can then be processed into various commodities. More specifically, in the production of glass fiber strands, molten glass flows from a suitable source to a heated bushing assembly. The bushing is generally an elongate channel having side walls, end walls, and a generally flat bottom. At the bottom are mounted a number of nozzles or chips through which the molten glass passes. In the region directly below these chips, molten glass is formed into a plurality of filaments. This area is a tapered area where the glass fiber is cooled, dimensioned to be applied to the fiber, and gathered together into a single strand. Finally, the twisted yarn is wound on a spool to form a glass package. The environment in the area directly below these chips is critical for filament formation. This is because the molten glass is cooled at that time. As the yarn filaments cool, their mechanical properties and physical dimensions are established.

For a more detailed description of a method and / or apparatus for producing filaments, see US Pat. Nos. 4,118,210, 3,040,377, 2,300,736, 4,018,586,
Nos. 4,646,234, 4,622,054, 4,325,722, and 4,866,536. These contents are incorporated herein by this reference.

There are four main factors that affect fiber formation in the formation area. They are air and
Fibers, fins, and chip plates. The chip plate temperature distribution affects the glass production (throughput) of each chip. The glass passes through the chip by gravity and is reduced to its final diameter by a tensioned take-up. As the jet of glass narrows from an initial diameter to a final diameter, the glass loses heat to the fins by radiation and loses heat convectively to the surrounding air. Also, air is drawn into the fiber fan from the surroundings by dragging the air. Air begins to penetrate the fiber from the end of the chip plate and reaches halfway. During this process, heat exchange occurs not only between the air and the chip plate, but also between the air and the fins. The air becomes progressively hotter towards the middle of the chip plate. In addition, the velocity component parallel to the tip plate becomes smaller as the entrained air is pulled down by the fiber (maximum at the end of the tip plate).
And finally "squeezed out" from the fiber fan. It is the history of thinning of each fiber (local diameter, speed and temperature) that governs the entrainment of air.
It is.

The entrained cooling air cools the chip plate. As a result of changes in air temperature and velocity, the heat transfer coefficient below the tip plate can be a function of local location. This means that air can contribute to the tip plate temperature slope, which means the difference in glass flow from chip to chip. In addition, air affects the history of thinning of the fiber (diameter, speed and temperature of the fiber as a function of position in the direction of thinning). The entrained air is relatively cool around the tip plate, relatively hot in the center of the chip plate, and changes in velocity, so that the air cools some of the fins while heating other parts of the fins. May be.

As has been observed, the thinning of the fiber contributes to the heat load of the fins and affects air temperature and entrainment. The thinning of the fiber is strongly influenced by the physical properties of the glass. These physical properties include viscosity, surface tension, density, specific heat, emissivity (sum of hemispheres), and thermal conductivity. Since glass is an absorbing and emitting medium, the total emissivity of the hemisphere (which determines the radiative heat loss from the fiber) and the thermal conductivity (which determines the heat conduction in the fiber) are the absorption and wavelength Depends on relationship data. These data are temperature dependent. In addition, hemispheric total emissivity and thermal conductivity are governed by optical thickness (absorptivity times distance) and temperature.

The fins exchange radiant heat between the tip plate and the thinning fiber. The fins also exchange heat with air by convection and conduction. The location and orientation of the fins below the chip plate can be very important. This is because not only the air flow but also the radiant heat exchange form factor is affected. The heat transfer coefficient in the fin manifold affects the heat removal of the fin and affects the fiber forming process.

The tip plate determines the glass conditions at the tip exit, exchanges radiant heat with the fins, and conducts convective and conductive heat transfer with the air. Airflow and temperature fields can create differences in temperature at each point of the chip plate.

It can be seen that depending on the entrained airflow and temperature fields, each fiber experiences a different thermal environment, and therefore has a different thinning history. This means that the initial cone angle can be different for each fiber, which results in different glass throughput. This is because the throughput, like other quantities, depends on the initial cone angle. Fluctuations in temperature in this region cause fluctuations in the diameter of the twisted yarn. Moreover, if the environment in the area directly below the bushing tip is excessively cooled, the filament formed by the bushing will have a relatively large diameter,
They may not be able to withstand the forces of collecting and winding them, causing the filament to break. Conversely, undercooled filaments can break due to instability.

In addition, the turbulent air flow can carry undesirable material into the tapered region, which can cause filament breakage and reduced production efficiency. Production efficiency is measured in terms of break rate or short term yardage. Production efficiency can also be measured in the amount of input, ie, material, energy, time, and machine savings required to achieve the same failure rate. Further, it is well known that by forcing air through a tapered region, perpendicular to the flow of the fiber, the fiber may spread in a different direction than an ordered filament. The discrete streams are then collected on a rotating drum and used as staple textile fibers. In a well-managed environment without forced airflow, ordered filaments may be combined into a high quality thread and wound on a spool as a glass package.

[0012] One typical application of such twisted yarns is in the formation of glass fabrics. In order to make a satisfactory knitted fabric, the diameter of each glass thread must be uniform. If the diameter of the glass thread varies in the length direction, the woven fabric does not flatten, but "wrinkles". Such fabrics are not acceptable.

Problems with conventional cooling devices include, for example, low productivity due to high breakage rates, uneven distribution of molten material to each chip, low quality fabrics due to variations in the diameter of the glass thread, high processing costs. Includes inefficiencies and inefficiencies due to high capital investment. Compared to the conventionally known method of blowing cooling air to the fiber,
The air curtain according to the invention is non-permeable and has the potential to aerodynamically isolate individual locations.

[0014] In view of the foregoing, it is an object of the present invention to provide an apparatus for producing high quality glass fiber. It is another object of the present invention to provide an apparatus for producing a glass fiber having a low breakage rate. Yet another object is to provide an apparatus for producing glass fibers with a simplified design and generally lower cost than conventional equipment of the same type. It is still another object of the present invention to provide an apparatus for manufacturing glass fibers that makes efficient use of cooling air.
Yet another object of the present invention is to provide a method for manufacturing a glass fiber using the disclosed apparatus.

[0015]

Summary of the Invention

Briefly, a method and apparatus for forming a continuous glass fiber is provided. The method comprises providing a plurality of streams of molten glass from a bushing,
Withdrawing the plurality of streams into a plurality of continuous glass filaments, and withdrawing the plurality of continuous glass filaments such that an amount of cooling air determined by the speed at which the glass filaments are withdrawn is entrained. Providing a flow of cooling air parallel to at least the front and back surfaces of the bushing, and then collecting the continuous filament.

An apparatus for distributing impervious cooling air to a tapered region of a bushing glass withdrawal process comprising a single bushing tip plate having a plurality of bushing tips includes a method for applying pressure to a plurality of outlets to a selected flow rate. At least two chambers including an inlet to which cooling air is supplied. The outlet extends for a length in the longitudinal direction of the bushing chip plate, thereby providing cooling air to the front and rear surfaces of the chip plate. The entrainment of the cooling air is a function of the speed at which the glass filament is withdrawn.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

In the drawings, like reference numbers indicate similar elements. Shown is a system and apparatus 10 for delivering convective cooling air 12 to a glass fiber tapered region of a bushing 14. As is well known, molten glass 16 is drawn through bushing tip 18 of bushing 14. A plurality of bushing chips 18 are arranged on the bushing chip plate. As the molten glass 16 passes through the bushing tip 18, it is narrowed down to form a conical glass. These cones are further finely squeezed into filaments 20, which are then collected into a synthetic thread.

Although the drawings show the invention as cooperating with a single bottom bushing, the invention does not limit the invention to having two bottom bushings, ie, two chip plates separated by a gap. It may be used with equivalent well-known devices that have.

The bushing tip 18 is typically cooled by a plurality of cooling fins 22 operably mounted on a liquid cooled manifold 24. Cooling fin 2
2 is operatively attached to manifold 24 so that heat is removed from the area around bushing tip 18. As shown in FIG. 1, the cooling fins 22
The bushing chips 18 are arranged between rows. FIG. 1 also shows the connection between each cooling fin 22 and the manifold 24 and the direction of the flow of the coolant in the manifold 24. Heat is removed through cooling fins 22 and ultimately (u
ltimately) removed by the liquid flowing through the manifold 24. As shown,
The manifold 24 is, for example, a hollow tube, and the cooling fins 22 are made of, for example, solid fin members. In another embodiment, as shown in FIG.
May be operably connected to the opposite side of the cooling fins 22. However, the particular means employed for such cooling is not critical to the operation of the present invention, and are all well known in the art.

In the figure, the system and apparatus 10 includes at least two plenum chambers 26.
In these plenum chambers 26, a cooling gas such as pressurized air is supplied at an appropriate flow rate. For efficient operation, the cooling air is not above ambient temperature. However, the cooling air may be cooled if desired. Cooling air enters the plenum chamber 26 through an inlet 28 and exits the system through an outlet 30. The outlets 30 extend on both sides of the chip plate 14 over the entire length thereof so as to provide a cover with sufficient cooling air. The outlet 30 is a yarn of about 50-300 pounds per hour (throughput).
Molds and reinforcement type bushings are designed to provide 150-300 cubic feet per minute of cooling air. However, the amount of cooling air may be adjusted as desired to suit the type of bushing design employed. The opening of the outlet 30 is less than 1% of the total surface area of the outlet.

FIGS. 2-5 show another embodiment of an apparatus for supplying cooling air to at least both the front and rear tapered regions of the chip plate 14, preferably at least the entire periphery of the chip plate. The plenum chamber 26 may be rectangular (FIGS. 4, 5).
) Also, the plenum chamber may be "boot-shaped" (FIGS. 2, 3). The plenum chamber 26 is provided with wings 3 for directing a flow of cooling air perpendicular to the chip plate 14.
2 may be provided. The outlet 30 may be above the plane of the cooling fins 22 (FIG. 4) or below the plane of the cooling fins 22 (FIGS. 2, 3).
, FIG. 5), or the same level (parallel) as the plane of the cooling fins 22 (shown by imaginary lines in FIG. 5). In a preferred embodiment, the outlet 30 of the plenum chamber 26 is about 0-4 inches from the horizontal end of the chip plate 14 and within 3 inches of the bottom of the chip plate. The cooling air exits the outlet 30 substantially vertically downward and enters a tapered nozzle immediately adjacent to the tip 18 to form a curtain of air at least on the front and back surfaces of the bushing, preferably all around the bushing. The local vacuum is created by the movement of the fiber, thereby causing the nominal (nom
An inal) velocity cooling air flow is created and the glass fibers can entrain the required coolant without changing the fiber diameter. A perforated screen (not shown) may be used that acts as a filter to reduce turbulence in the cooling gas and prevent any particulate matter from contacting the forming glass fiber filaments. Furthermore, a curtain of air distributes the majority of the cooling air substantially vertically downward, at least on the front and back surfaces of the chip plate 14, preferably around the entire circumference of the chip plate, whereby the tapering fibers are It can be seen that the required amount of cooling air is entrained as the fiber moves (dictated). A minor portion of the cooling air may be angled with respect to the glass fiber so as not to disturb the tapered region. Compared to the conventional method of blowing cooling air onto the fiber, the air curtain is impermeable,
Each location has the potential to be aerodynamically isolated from one another. Furthermore, by supplying cooling air only parallel to the direction of flow of the glass fibers, and at least both the front and rear surfaces of the chip plate 14, the amount of cooling air required to achieve the same effect is: It has been found that there is less than previously known systems, and that short term yardage is also improved.

In operation, the bushing is supplied with molten glass, which passes through the tip 18. The fin plate 22 is suitably positioned below the tip plate 14 and the liquid coolant passes through the manifold at a desired rate to extract heat from the fin plate. Cooling air is introduced into the plenum chamber 26 and flows through the diffuser screen, undisturbed, on both sides of the chip plate, parallel to the glass fiber draw-out direction. Cooling air is introduced into the tapered region so that the filament is tapered in a uniform environment.

The patents and publications cited herein are incorporated as part of the specification.

Although the presently preferred embodiment of the present invention has been described above, it will be understood that the present invention may have other embodiments within the scope of the claims.

[Brief description of the drawings]

FIG. 1 is a bottom view of a bushing including a cooling air delivery device according to the present invention.

FIG. 2 is a cross-sectional view of the bushing of FIG. 1 taken along line 2-2.

FIG. 3 is a sectional view taken along line 2-2 of the bushing of FIG. 1 utilizing another cooling air delivery device according to the present invention.

4 is a cross-sectional view of the bushing of FIG. 1 taken along line 2-2 utilizing another cooling air delivery device according to the present invention.

FIG. 5 is a sectional view taken along line 2-2 of the bushing of FIG. 1 utilizing another cooling air delivery device according to the present invention.

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR , BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS , JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZA, ZW (72) Inventor Sriniva San Sesshadri, Ohio 43085 U W. Ossington Orenwood Avenue 490 (72) Inventor: Andrew Andrew, Ohio 43760 Munt Perry Malbury Road Southeast 9517 F-term (reference) 4G021 MA03 [Continued] is a function of the speed at which the glass filament 20 is withdrawn.

Claims (10)

[Claims] 1. A method for producing a continuous glass fiber, comprising: supplying a plurality of streams of molten glass from a bushing; extracting the plurality of streams into a plurality of continuous glass filaments; A stream of cooling air parallel to the direction of withdrawal of the plurality of continuous glass filaments is provided on at least a front and a back of the bushing such that an amount of cooling air determined by the speed of withdrawal is entrained. And collecting the continuous filament. 2. The method of claim 1 wherein 150 to 300 cubic feet per minute of cooling air are provided. 3. The method of claim 1, wherein the flow of cooling air is substantially vertically downward. 4. The method of claim 1, wherein the cooling air flow is at ambient temperature. 5. The flow of cooling air is provided at least on the front and rear surfaces of the bushing, around the entire circumference of the bushing, parallel to the direction of drawing out of the continuous glass filament flow. The method of claim 1. 6. An apparatus for distributing impervious cooling air to a tapered region of a bushing glass withdrawal process comprising a single bushing tip plate having a plurality of bushing tips, wherein the pressure is selected to a plurality of outlets. At least two chambers including an inlet through which cooling air is supplied at a predetermined flow rate, wherein the outlet extends a length of the bushing chip plate in a longitudinal direction thereof, whereby a front surface of the chip plate and An apparatus, wherein cooling air is provided on a rear surface, and the entrainment of the cooling air is a function of the speed at which the glass filament is withdrawn. 7. The apparatus according to claim 6, wherein said outlet is located above a plane formed by a plurality of cooling fins fixed below said bushing tip plate. 8. The apparatus of claim 6, wherein said outlet is located below a plane formed by a plurality of cooling fins fixed below said bushing tip plate. 9. The method according to claim 6, wherein the discharge port is positioned substantially parallel to a plane formed by a plurality of cooling fins fixed below the bushing chip plate. apparatus. 10. The method of claim 10, wherein the cooling air exits substantially vertically below immediately adjacent the plurality of chips to form air curtains on the front and rear surfaces of the bushing. Item 6. The apparatus according to Item 6.