WO1996009258A1

WO1996009258A1 - Dual glass delivery system

Info

Publication number: WO1996009258A1
Application number: PCT/US1995/011503
Authority: WO
Inventors: Steven F. Geiger; Rodrick S. Cook; Lawrence J. Ploetz
Original assignee: Owens Corning; Owens Corning Fiberglas Corp
Current assignee: Owens Corning
Priority date: 1994-09-21
Filing date: 1995-09-13
Publication date: 1996-03-28
Anticipated expiration: 1997-03-21
Also published as: AU3509895A; ZA957892B; TR199501159A2

Abstract

A process and apparatus (10, 90) are provided for making dual glass fibers. The apparatus (10, 90) includes equipment for providing first and second molten glass compositions. A delivery system (20) receives the first and second molten glass compositions from the equipment and separately transports the first and second glass compositions to at least one receiving station. At least one fiberizer (30) which defines the at least one receiving station is provided for receiving the first and second molten glass compositions and producing dual glass fibers therefrom.

Description

DUALGLASSDELIVERYSYSTEM

BACKGROUND ART This invention relates to apparatus for manufacturing dual component fibers from thermoplastic materials and, more particularly, to a dual glass delivery system for receiving first and second molten glass compositions from melting equipment and separately transporting the first and second glass compositions to at least one glass fiber forming device.

Fibers of glass and other thermoplastic materials are useful in a variety of applications including acoustical or thermal insulation materials. Common prior art methods for producing glass fiber insulation products involve producing glass fibers from a rotary process. A single molten glass composition is delivered from a conventional melter via a conventional forehearth to a centrifuge, commonly known as a spinner. The forehearth defines only a single delivery channel through which the single glass composition travels. Generally, the forehearth supplies a plurality of spinners with glass material. Each spinner produces primarily short, straight glass fibers.

The fibers produced by the spinners are drawn downward by a blower. A binder, which is required to bond the fibers into a wool product, is sprayed onto the fibers as they are drawn downward. The fibers are then collected and formed into a wool pack. Existing glass wool insulation materials produced using the aforementioned process have been found to have significant nonuniformities in the distribution of fibers within the product. This adversely affects the insulating capability of the insulation product. A further disadvantage is the required use of a binder. Not only is the binder itself expensive, but great pains must be taken to process effluent from the production process due to the negative environmental impact of most organic compounds.

Accordingly, a need exists for a method and apparatus for producing an improved wool insulating material which has a generally uniform volume filling nature and which is substantially devoid of binder material. It would also be desirable to develop a process which allows existing fiber forming apparatus to be modified for use in producing the improved wool material. DISCLOSURE OF INVENTION In accordance with the present invention, a delivery system is provided which delivers two separate glass compositions to one or more fiberizers from which dual component glass fibers having an irregular shape are produced. These fibers are then formed into wool insulating products. Such products have a substantially uniform volume filling nature and sufficient product integrity such that use of an organic binder may not be required. The delivery system of the present invention allows existing melters which have typically been used in the manufacture of single component glass fibers to be used in the manufacture of dual component glass fibers. In accordance with one aspect of the present invention, apparatus is provided for making dual glass fibers. The apparatus comprises: equipment for providing first and second molten glass compositions; a delivery system for receiving the first and second molten glass compositions from the equipment and separately transporting the first and second glass compositions to at least one receiving station; and, at least one fiberizer which defines the at least one receiving station for receiving the first and second molten glass compositions and producing dual glass fibers therefrom.

The equipment may comprise a first melter for providing the first molten glass composition and a second melter for providing the second molten glass composition. Alternatively, the equipment may comprise a single, dual-chamber melter for providing both the first and second molten glass materials.

The delivery system includes first and second forehearths. The first and second forehearths may be positioned generally parallel to one another. The first and second forehearths respectively define first and second delivery channels which transport and deliver the first and second glass compositions to first and second forehearth discharge stations positioned adjacent to the at least one receiving station. The first and second forehearths respectively further define first and second combustion chambers.

The first forehearth includes first discharge structure which defines the first discharge station for discharging the first glass composition to the at least one receiving station. The second forehearth includes second discharge structure which defines the second discharge station for discharging the second glass composition to the at least one receiving station. The first discharge structure includes a first flow block having a first asymmetric orifice with a first outlet for directing the first glass composition to the at least one receiving station. Similarly, the second discharge structure includes a second flow block having a second asymmetric orifice with a second outlet for directing the second glass composition to the at least one receiving station. In an alternative embodiment, the first and second orifices are symmetrical. The first delivery channel has a first longitudinally extending centerline and the second delivery channel has a second longitudinally extending center line which is separated a first distance from the first center line. The first and second outlets are spaced a second distance from one another. The first distance is greater than the second distance. The delivery system may include a first receiving channel for accepting the first molten glass composition from the equipment and transporting the first glass composition to the first forehearth and a second receiving channel for accepting the second molten glass composition from the equipment and transporting the second glass composition to the second forehearth.

In accordance with a second aspect of the present invention, a process is provided for making dual glass fibers. The process comprises the steps of: providing first and second distinct molten glass compositions; delivering separately the first and second molten glass compositions to at least one receiving station; and centrifuging at the receiving station dual glass fibers from the first and second glass compositions.

Accordingly, it is a feature of the present invention to provide an apparatus for forming dual component glass fibers. It is a further feature of the present invention to provide a delivery system which delivers two separate glass compositions to one or more fiberizers from which dual component glass fibers having an irregular shape are produced. These and other features and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims. BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is a plan view of first and second melters and a delivery system for transporting and delivering first and second distinct glass compositions to one or more fiberizers;

Figure 2 is a schematic side view of a forehearth forming part of the delivery system shown in Figure 1;

Figure 3 is a sectional view taken along line 3-3 in Figure 2; Figure 3 A is an enlarged, partially sectional view of a portion of one discharge station shown in Figure 3;

Figure 4 is a plan view of the first and second discharge stations;

Figure 5 is a sectional view taken along line 5-5 in Figure 4; Figure 6 is a perspective sectional view of a flow block;

Figure 7 is a sectional view taken along line 7-7 in Figure 2;

Figure 8 is a sectional view taken along line 8-8 in Figure 2; and,

Figure 9 is a plan view of a dual-chamber melter and a delivery system formed in accordance with a second embodiment of the present invention. MODES FOR CARRYING OUT THE INVENTION

The invention will be described in terms of apparatus for making irregularly shaped (i.e., nonstraight along their axial length) dual glass fibers, although it is to be understood that the invention encompasses apparatus for making other types of dual glass fibers such as curly (helical) fibers and dual component fibers of other thermoplastic materials such as polyester or polypropylene, or combinations of glass and polymer.

Apparatus 10 for forming dual glass fibers is shown in Figure 1. The apparatus 10 comprises first and second conventional furnaces or melters 11a and lib which provide two distinct molten glass compositions (A glass and B glass) to a delivery system 20 which, in turn, separately transports and delivers the A and B glass compositions to a plurality of rotary fiberizers 30, see also Figures 2 and 3. The rotary fiberizers 30 may be construαed and utilized to make dual glass fibers as set out in U.S. Patent Application Serial No. 08/148,098, entitled DUAL-GLASS FIBERS AND INSULATION PRODUCTS THEREFROM, filed on November 5, 1993, the disclosure of which is hereby incorporated by reference. Preferably, the A and B glasses have different mechanical attributes so that upon cooling, they will assume an irregular (as opposed to straight) configuration. Such different mechanical attributes may be, for example, differing coefficients of thermal expansion, differing melting points, differing viscosities, or differing mechanical strengths. Veils (not shown) of dual glass fibers, such as irregularly shaped glass fibers produced by the fiberizers 30, are collected as a wool pack in the manner set out in the referenced '098 application.

Referring again to Figure 1, the delivery system 20 comprises first and second receiving channels 12a and 12b and first and second generally parallel forehearths 40 and 50 which are defined by a single forehearth structure 60. The A glass flows from a discharge orifice (not shown) in melter 1 la through the first receiving channel 12a and into the first forehearth 40. Similarly, the B glass flows from a discharge orifice (not shown) in melter 1 lb through the second receiving channel 12b and into the second forehearth 50. 5 The first and second forehearths 40 and 50 define respectively first and second delivery channels 42 and 52, see Figures 3, 7, and 8. The channels 42 and 52 transport and deliver the A and B glass compositions to one or more first and second discharge stations 44 and 54, which, in turn, discharge the A and B glasses to one or more fiberizers 30, see Figure 3. One first discharge station 44 and one second discharge station

10 54 are positioned adjacent to each fiberizer 30 so as to supply A and B glasses to each fiberizer 30. In the illustrated embodiment, four first discharge stations 44 and four second discharge stations 54 are provided for four fiberizers 30, see Figure 1.

Each first discharge station 44 is defined by a first flow block 44a, a first bushing block 44b, and a first platinum bushing 44c, see Figures 3, 4, and 5. The bushing

15 44c is held against the first bushing block 44b via a plurality of bushing clamps 45a, four in the illustrated embodiment, which engage a first ceramic holder 45b positioned over the bushing 44c. The clamps 45a are fixedly connected to a first bushing hanging plate 45c which, in turn, is fixedly connected to steel forehearth plate 46. Each second discharge station 54 is defined by a second flow block 54a, a second bushing block 54b, and a second 0 bushing 54c, see also Figure 3A. The bushing 54c is held against the first bushing block 54b via a plurality of bushing clamps 55 a, four in the illustrated embodiment, which engage a first ceramic holder 55b positioned over the bushing 54c. The clamps 55a are fixedly connected to a second bushing hanging plate 55c which, in turn, is fixedly connected to the forehearth plate 46. The first and second hanging plates 45c and 55c are spaced from one another. 5 The first and second flow blocks 44a to prevent electromagnetically induced currents and 54a are configured such that the A and B glasses are delivered directly to desired locations within the fiberizer 30 without the need for any intermediate directing means. In the illustrated embodiment, the first flow block 44a has a first asymmetric orifice 44d with a first outlet 44e which together with bushing 44c directs the A glass through a first 0 fiberizer tube 32a and into the fiberizer 30 such that the A glass contacts at a first desired location within the fiberizer 30, see Figures 3, 4, and 5. The second flow block 54a has a second asymmetric orifice 54d with a first outlet 54e which together with bushing 54c directs the B glass through a second fiberizer tube 32b and into the same one fiberizer 30 such that the B glass contacts at a second desired location within the fiberizer 30. Preferably, the A and B glasses do not engage the first and second tubes 32a and 32b as they pass therethrough. Since the first and second orifices 44d and 54d in combination with bushings 44c and 54c route the A and B glasses directly to desired locations within the fiberizer 30, intermediate directing means such as directing tubes are not required. Tubes or other like intermediate directing means tend to wear out over short time periods and do not always maintain stable positions. Hence, such directing means are undesirable.

The first delivery channel 42 has a first longitudinally extending centerline 42a and the second delivery channel 52 has a second longitudinally extending center line 52a which is separated a first distance D, from the first center line, see Figure 5. The first and second outlets are spaced a second distance D. from one another. The first distance D, is greater than the second distance D₂.

Extending into the first and second delivery channels 42 and 52 are a plurality of conventional electrodes 70, see Figures 2, 7, and 8. The electrodes 70 serve as a primary source for transferring energy in the form of heat to the A and B glass compositions during fiber production to maintain those glass compositions molten as they pass through the channels 42 and 52. The preferred number of electrodes 70 and the spacing between adjacent electrodes 70 may be varied as is known in the art in order to maintain the glass compositions molten.

The first and second forehearths 40 and 50 also define first and second combustion chambers 48 and 58, see Figures 3, 7, and 8. A plurality of gas-fired burners 72 are associated with the first and second chambers 48 and 58 and serve to transfer energy in the form of heat to the first and second combustion chambers 48 and 58 during fiber produαion. Should a power failure occur preventing the electrodes 70 from funαioning, the amount of heat that is generated by the gas-fired burners 72 can be increased to maintain the A and B glasses molten. Chimney passages 48a and 58a are provided to vent combustion gases from the chambers 48 and 58 to atmosphere, see Figures 7 and 8.

Referring again to Figures 3, 7, and 8, the forehearth structure 60 which defines the first and second forehearths 40 and 50 will now be described. The forehearth structure 60 is constructed from a plurality of glass contaα blocks 20a, firebricks 20b, insulation blocks 20c, and back-up blocks 20d. The glass contaα blocks 20a may comprise bonded alumina-chromia compositions having a chromia content ranging from about 1% to 96%. Such glass contaα blocks are commercially available from North American Refraαories Company under the produα name "SERV" and from Corhart Refraαories Corporation under the produα name "Zirchrom." The blocks 20a may also comprise fused cast chrome-alumina blocks which are commercially available from The Carborundum Company under the produα name "Monofrax K-3," or zirconia-alumina-silica refraαory which is commercially available from The Carborundum Company under the produα names "Monofrax S-3," "Monofrax S-4," and "Monofrax S-5." The firebricks 20b may comprise mullite brick which are commercially available from North American Refraαories Company under the produα name "Tamul." The insulation blocks 20c may comprise conventional insulating firebrick. The back-up blocks 20d may comprise pressed zircon which is commercially available from North American Refractories Company under the produα name "TZB"; alumina-fireclay, which is commercially available from Harbison-Walker Refractories under the product name "Ufala"; or an insulating clay flux which is commercially available from Findlay under the produα name "Finsulation."

Each forehearth 40 and 50 includes a plurality of access openings 49 and 59 which, in the illustrated embodiment, are positioned in proximity to the first and second discharge stations 44 and 54, see Figure 3. During production, the openings 49 and 50 are normally closed offby a like number of movable access cover blocks 49a and 59a. However, during start-up, the access cover blocks 49a and 59a are moved to allow end tips of start-up burners (not shown) to be positioned in the first and second delivery channels 42 and 52. The start-up burners extend through peep holes 49b and 59b in the forehearths 40 and 50. The openings 49 and 50 further provide repair access to the inside portions of the discharge stations 44 and 54. During fiber produαion, the peep holes 49b and 59b are closed offby removable blocks, such as firebrick. The number of peep holes 49b and 59b is generally equal to the number of access openings 49 and 59.

The flow blocks 44a and 54a, and the access cover blocks 49a and 59a may be formed from the same material as the glass contaα blocks 20a. The bushing blocks 44b and 54b may be formed from isostatically pressed or slip cast dense zircon, which is commercially available from A.P. Green Industries, Inc. under the product name "ISO-Z-245." The glass contaα blocks 20a, the firebricks 20b, the insulation blocks 20c, the back-up blocks 20d, the bushing blocks 44b and 54b, and the flow blocks 44a and 54a are friαionally held together by conventional clamping mechanisms (not shown). While mortar (not shown) may be used between one or more of the blocks 20a through 20d, it serves mainly to seal joints between the blocks.

As shown in Figure 1, the first and second forehearths are provided with drain openings 80. The openings 80 allow for drainage of the A and B glass compositions should one or more of the fiberizers 30 become disabled. Thus, after the disabled fiberizer has become operational again, restarting of the forehearths 40 and 50 may not be necessary. Each of the first and second receiving channels 12a and 12b is construαed in generally the same manner and from generally the same refraαory materials as the forehearth structure 60. The channels 12a and 12b are also provided with an appropriate number of heating eleαrodes and gas-fired burners.

Apparatus 90 for forming dual glass fibers, formed in accordance with a second embodiment of the present invention, is shown in Figure 9, where like reference numerals indicate like elements. Apparatus 90 is essentially the same as apparatus 10 shown in Figure 1, except that a single, dual-chamber furnace or melter 91 is provided. The delivery system 20 receives the two distinct molten glass compositions (A glass and B glass) output from the melter 91 and separately transports and delivers the A and B glass compositions to a plurality of rotary fiberizers 30.

While certain representative embodiments and details have been shown for purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes in the methods and apparatus disclosed herein may be made without departing from the scope of the invention, which is defined in the appended claims.

Claims

CLAIMS 1. Apparatus for making dual glass fibers comprising: equipment for providing first and second molten glass compositions; a delivery system for receiving said first and second molten glass compositions from said equipment and separately transporting said first and second glass compositions to at least one receiving station; and, at least one fiberizer which defines said at least one receiving station for receiving said first and second molten glass compositions and producing dual glass fibers therefrom.

2. Apparatus as set forth in claim 1, wherein said equipment comprises a first melter for providing said first molten glass composition and a second melter for providing said second molten glass composition.

3. Apparatus as set forth in claim 1, wherein said delivery system includes first and second forehearths, said first and second forehearths respeαively defining first and second delivery channels which transport and deliver said first and second glass compositions to first and second forehearth discharge stations positioned adjacent to said at least one receiving station.

4. Apparatus as set forth in claim 3, wherein said first forehearth includes first discharge structure which defines said first discharge station for discharging said first glass composition to said at least one receiving station and said second forehearth includes second discharge structure which defines said second discharge station for discharging said second glass composition to said at least one receiving station.

5. Apparatus as set forth in claim 4, wherein said first discharge structure includes a first flow block having a first asymmαric orifice with a first outlet for direαing said first glass composition to said at least one receiving station and said second discharge structure includes a second flow block having a second asymmαric orifice with a second outlet for direαing said second glass composition to said at least one receiving station.

6. Apparatus as set forth in claim 5, wherein said first delivery channel has a first longitudinally extending centerline and said second delivery channel has a second longitudinally extending center line which is separated a first distance from said first center line, and said first and second outlets are spaced a second distance from one another, said first distance being greater than said second distance.

7. Apparatus as sα forth in claim 3, wherein said delivery system further includes a first receiving channel for accepting said first molten glass composition from said equipment and transporting said first glass composition to said first forehearth and a second receiving channel for accepting said second molten glass composition from said equipment and transporting said second glass composition to said second forehearth.

8. Apparatus as sα forth in claim 7, wherein said first and second forehearths are positioned generally parallel to one another.

9. Apparatus as set forth in claim 3, wherein said first and second forehearths respeαively further define first and second combustion chambers.

10. Apparatus as set forth in claim 1, wherein a plurality of fiberizers are provided and each fiberizer defines one of a plurality of receiving stations, said delivery system transporting said first and second glass compositions to each of said fiberizers which produce dual glass fibers therefrom.

11. Apparatus as set forth in claim 1, wherein said equipment comprises a single, dual-chamber melter for providing both said first and second molten glass materials.

12. A process for making dual glass fibers comprising the steps of: providing first and second distinα molten glass compositions; delivering separately said first and second molten glass compositions to at least one receiving station; and centrifuging at said receiving station dual glass fibers from said first and second glass compositions.

13. A process as set forth in claim 12, wherein said first and second molten glass compositions are delivered to a plurality of receiving stations.