US3640793A

US3640793A - Self-cleaning hood structure

Info

Publication number: US3640793A
Application number: US9761A
Authority: US
Inventors: James W Scott
Original assignee: Owens Corning Fiberglas Corp
Current assignee: Owens Corning
Priority date: 1970-02-09
Filing date: 1970-02-09
Publication date: 1972-02-08
Anticipated expiration: 1989-02-08
Also published as: CA1002715A; DE2106048A1; BE762637A; SE374347B; FR2079325B1; FR2079325A1; NL7100616A; GB1331336A; JPS4838351B1

Abstract

A forming hood having an endless belt as a sidewall thereof. The endless belt is supported from a trolley at the top, so that it is free to oscillate laterally, and preferably includes at least one head or tail pulley having longitudinal projections which flex the belt as it traverses the pulley. The endless belt preferably has a critical surface tension of wetting that is less than the surface tension of the binder used in the forming hood, and may also include a seal between the bottom edge of the belt and the forming conveyor on which the pack is made. The seal preferably includes passage means for communicating reduced pressure to the back side of the belt to keep the edge adjacent the forming conveyor from moving laterally.

Description

[ Feb. 8, 1972 United States Patent Scott [54] SELF-CLEANING HOOD STRUCTURE 3,252,691 5/1966 Getzen et a1...........................198/230 [72] Inventor: James W. Scott, Newark, Ohio Primary Examiner senjamin A Borchelt [73] Assignee: Owens-Corning Fiberglass Corporation Assistant ExaminerHarld J. Tudor [22] Filed:

Feb. 9, 1970 Attorney-Staelin and Overman and William P. Hickey ABSTRACT A forming hood having an endless belt as a sidewall thereof. The endless belt is supported from a trolley at the top, so that [21] Appl. No.:

it is free to oscillate laterally, and preferably includes at least one head or tail pulley having longitudinal projections which flex the belt as it traverses the pulley. The endless belt preferably has a critical surface tension of wetting that is less than the surface tension of the binder used in the forming hood, and may also include a seal between the bottom edge of the belt and the forming conveyor on which the pack is made.

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UNITED STATES PATENTS The seal preferably includes passage means for communicating reduced pressure to the back side of the belt to keep the edge adjacent the forming conveyor from moving laterally.

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INVENTOR.

JAMES M 56077 .4 TTORNE YS PATENTEU B 3 I973 SHEET 3 BF 3 INVENTOR. LAM/[.5 M 56077 A BY SELF-CLEANING HOOD STRUCTURE BACKGROUND OF THE INVENTION fibers. The'fibers may be made in a variety of different ways.

Inone common" method of making the fibers, centrifuges are used to flow small streams of molten glass into hot high velocity gas streams whichare projected downwardly towards the product conveyor. In still other instances, small streams of glass flow from tiny orifices into the path of steam jets, or products of combustion, which flow downwardly towards the product conveyor. Aqueous solutions of organic binders are put onto the fibers asthey are deposited into the forming hood, and after a period of time, a layer of binder and fibers builds up on the sidewalls of the forming hood. This binder build up creates a cleaning problem, and if the binder is not completely removed at regular interval, the binder which adheres to the sidewalls become sticky and cures to'a solid state which is difficult to remove.

An object of the present invention is the provision of a new and improved hopper structure or forming hood having movable sidewalls that are substantially self-cleaning and which greatly reduce the amount of washing that is necessary to keep the sidewalls clean.

' A further object of the invention is the provision of a'movable sidewall structure which utilizes an endless belt that is hung from its top side edge in a manner allowing lateral oscillation.

A still further object of the invention is the provision of a movable sidewall structure of the above-described type and which has a surface whose critical surface tension of wetting is less-than the surface tension of the liquid binder that is used, so that the surface tension of the binder can be utilized to provide a minimum of contact area between the fibers and the movable sidewalls.

A still further object of the invention is the provision of a movable sidewall structure of the immediately abovedescribed type, the endless belt of which is capable of being flexed continuously in any direction without rupture, and one of the head or tail pulleys of which is provided with longitudinally extending projections which contact the endless belt and over which the endless belt is sharply bent as the belt traverses the pulley structure. Further objects and'advantages of the present invention will become apparent to those skilled in the art to which the invention relates from the following description of the preferred embodiments described with reference to the accompanying drawings forming apart of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENTS While the invention may be embodied in many types of materialcollection facilities, it is herein shown and described as embodied in apparatus for forming packs of glass fibers. The apparatus shown in the drawings for producing packs of glass fibers generally comprises a glass furnace having a forehearth l2 proceeding therefrom to deliver the molten glass to a plurality of forming stations 14, one of which is shown in solid lines and others of which are shown by dotted lines. The bottom'of the forehearth at each forming station is provided with a metal plate 16 having a hole therein for delivering a stream of molten glass 18 into the hollow shaft 20 of a motor-driven centrifuge 22. A motor 24 surrounds the top end of the hollow shaft'20, and a centrifuge basket 26 having a plurality of openings in its outer periphery is fixed to the bottom end of the shaft 20. A- plurality of small molten streams of glass are thrown from the openings in the basket 26, and a downward flow of gases over the edge of the basket 26, produced by means not shown, causes the molten streams of glass to be attenuated into small filaments that are dispersed in the stream of gases in what are known as a veil 28. The apparatus preferably includes a multiplicity of veil-producing mechanisms 14, and four are shown in FIG. I.

' The glass fibers from the various veils 28 are collected on the top foraminous run 30 of a horizontal conveyor 32 having a head pulley 34 and tail pulley 36. A suction box 38 is positioned beneath the top run 30 to draw a large volume of gas downwardly through the top run 30 and cause the fibers of the veil to be deposited upon the top surface of the conveyor 32 in the form of apack 40. The swirling volume of gases and fibers which constitute the veil do not assume the cylindrical shape shown in the .drawings, but spread out violently in all directions and must be confined to the top surface on the conveyor 32. Inthe embodiment shown, thefibers and gases are confined to the top run 30 by a pair of parallel sidewalls 42, a stationary rear end wall 44, a front end wall 46, and a roll gate 48.

The pack of loose fibers as is formed within the confines of the wall above described (hereinafter called forming hood), is bonded together by a binder which is sprayed into the confines of the forming hood through a plurality of nozzles 50. The binder that is used is an aqueous solution which permeates the pack. Droplets of the binder solution are held at crossover points of the fibers forming the pack, and the binder impregnated pack 40 is delivered to a curing oven 52 where the water is removed and the binder is cured to a thermoset condition. In the present instance, the binder which is used is an aqueous solution of a phenol formaldehyde resite. The bottom edge of the front end wall 46 is positioned well above the height of the fibers collected in the forming hood, and the rear edge of the roll'gate 48 is generally tangent to the top edge of the front end wall 46 to generally close off the forming hood and smoothen out the fibers issuing from the forming hood.

The apparatus so far described comprises the generally conventional portions of apparatus that are sued to form bonded mats and batts'of glass fibers, such as are used for example, as building insulation materials. Considerable difiiculty has been encountered with the conventional apparatus in that the binder material causes wads of the fibers to stick to the sidewalls of the forming hood. It has been proposed to form the lateral sidewalls 42 from pieces or sheets of metal which can be moved'out of the forming hood and cleaned. While movable metal sidewalls have reduced the amount of material collected on the sidewalls within the forming hood, they have not prevented the fibers from sticking onto the sidewalls intermediate the periods of time that the sidewalls are cleaned so that a product is produced containing wads of fibers which are not intergraded with the rest of the pack.

According to the present invention, it has been found that a material having a critical surface tension of wetting below approximately 35 dynes/cm. eliminates build up of fibers on the sidewalls of the forming hoods, to substantially eliminate the production of wads." Materials having a critical surface tension of wetting below approximately 35 dynes/cm. and with which applicant is familiar, are nonmetallic and have insuffi cient strength to be self-supporting. Materials having a critical surfacetension of wetting of 35 dynes/cm. or less, can be used as paints or coating on existing structural surfaces. Further advantages of the invention are had, however, when the materials are used and supported in the manner about to be described.

According to further aspects of the invention, the sidewalls 42 of the forming hood are formed by a pair of endless belts 54 whose surfaces have a critical surface tension of wetting of 35 dynes/cm. or less and the top side edge of which are hung from overhead support structure. The endless belts 54 are nonrigid, nonself-supporting, and very flexible. It has been found that by supporting them from their upper edge, a slight movement or pulsation of the belt material is produced by the gases which blow the fibers into the forming hood. The pulsation, in combination with a belt material having a critical surface tension of wetting of 35 dynes/cm. or less, practically eliminates the problem of the adherence of fibers to the sidewalls of the hood, and the build up of the fibers into wads." The only materials known to applicant which have a critical surface tension of wetting of 35 dynes/cm. or less are soft stretchable materials whose use creates supporting problems.

In the apparatus shown in the drawings, the lateral sidewalls 42 are formed by the adjacent runs of a pair of the parallel belts 54. Each endless belt 54 extends around and is tensioned by spaced apart end members which in the present instance are head and

tail pulleys

56 and 58, best seen in FIG. 2. In the embodiment shown in the drawings, the shaft 60 of the tail pulley 58 is rotated by an electric motor driven gear reducing unit 62 to cause the belt to move continuously. In order that packs of various widths can be made, the head and

tail pulleys

56 and 58 are mounted on a longitudinally extending frame 64, which can be moved laterally. The tail pulley end of the frame 64 is provided with rollers 66 having a V-shaped groove in their periphery. The rollers rest on the apex of an angle iron 68 which is mounted on the top surface of a laterally extending I-I-beam. The head pulley end of the frame 64 is provided with conventional rollers 72 which roll along the flat top surface of a companion laterally extending I-I-beam 74, so that the entire endless belt structure is supported on a frame which can be moved laterally.

The endless belt 54 shown in the drawing is %in. thick and comprises 3-ply of woven dacron impregnated and coated with neoprene rubber. The endless belt 54 is supported at its top edge by a plurality of pairs of rollers 76 which ride along the horizontal flange portions of an inverted T-rail 78. The rollers 76 are affixed to the adjacent sides of a pair of angle brackets 80, the lower ends of which abut opposite sides of the belt 54 and are clamped together by a through bolt, not shown. The T-rail 78 is positioned directly above the longitudinal runs of the endless belt, and is provided with a curved section that is positioned directly over the belt as it rounds the tail pulley 58. Another curved section of T-rail is provided over theend periphery of the head pulley 56 so that the T-rail in effect forms a continuous loop which directly overlies the endless belt. It will be seen that the head and tail pulleys must be adjustable relative to each other in order to provide takeup for tensioning the adjustable, stretchable, belt 54. It will further be seen that a problem exists in keeping the trolley support over the top edge of the belt while accommodating the stretching movement of the belt. In the embodiment shown in the drawings, this is overcome by making the curved end portion of the T-rail section which overlies the head pulley S6 movable endwise of the remainder of the T-rail loop. Also in the embodiment shown, the head pulley end curved section is supported from the housing which supports the bearing structure for the head pulley, so that it is automatically adjusted at the same time that the head pulley is adjusted. In order that each pair of rollers will support the belt during the time that the rollers 76 are transferring across the gap between the fixed section of the T-rail structure and the adjustable section of T-rail structure, the end adjustable section is cut off at a angle, as shown in FIG. 3, and the remainder of the loop is provided with a mating taper. It will be seen that the 20 angle is such that only one roller of each pair traverses the gap between the sections of T-rail at any one time, and that the other roller of the pair can support the belt during this transfer.

It is a further feature of the invention that the portion of the belt which is most likely to be contacted by the binder is caused to traverse a portion of the head and/or tail pulley whose effective periphery is formed by parallel spaced-apart bars over which the belt is flexed sharply to flake off any material that may stick to the surface of the belt. As best seen in FIG. 2 the embodiment shown in the drawings includes lower pulley portions 82 having spaced parallel bars 84 which are fixed to the shafts of the respective head and tail pulleys. The outer edge of the parallel bars may have a radius that is the same as the radius of the main cylindrical body portion of its respective pulley, but in the preferred embodiment shown in the drawing, it is just slightly larger to offset the foreshortening which takes place as the belt assumesa chordal position between the projections 84, and in addition provides a small incremental stretching of the belt over that experienced in the main body portion of the belt. In the embodiment shown in the drawings, the head pulley and curved T-rail section are moved longitudinally to provide the necessary takeup by a pair of hydraulic cylinders 86. The top bearing for the shaft 60 of the head pulley 56 is a thrust bearing mounted upon a saddle 88 which slides along the frame 64 to provide the necessary support for the head pulley structure.

The bottom edge of the belt 54 terminates a slight distance above the top surface of the foraminous collection surface of the horizontal conveyor 32 so as to provide running clearance therewith. The suction pan 38 is vpositioned beneath the foraminous surface 30, and in order to prevent the loss of suction along the back side of the belt 54, a 1% inch thick wooden plank 90 ispositioned over the surface 30 in line with the back side of the belt 54. The plank 90 is supported by an adjustable angle iron 92 from the frame 64, and the plank 90 additionally I provides a suitable guide for the bottom edge of the belt to prevent undue whipping around of the lower portion of the belt 54. In some instances it will be desirable to hold the bottom edge of the belt against the plank 90 and this can be conveniently accomplished by providing tapered slots 94 in the plank to increase the suction between the plank and the bottom edge of the belt.

As previously indicated, glass fibers are blown into the forming hood by streams of high velocity gases and it has been found that this flow of high velocity gas will produce an oscillation or pulsation of the belt 54 unless otherwise prevented. This oscillation of the belt will help to continually throw off fibers which impinge upon the surface of the belt, so that in many instances no backup surface for the belt will be desired. In the embodiment shown in the drawings, however, sections of backup plate 96 are carried by the frame 64 to limit the outward movement of the bolt 54. The belt 54 is otherwise free to slide over the surface of the backup plate 96.

As previously stated, it has been found that surfaces having a critical surface tension of wetting no greater than approximately 35 dynes/cm. will, when hung in'the manner above described so as to be capable of a slight shaking movement, rid themselves continuously of binder and fibers to thereby prevent the formation of wads. Other types of materials which have been found to have these properties include silicone rubber, butadiene rubber, acrylonitrile rubber, polyurethane rubber, polyethylene, polypropylene, and other polymers which are sufficiently flexible. The sheet material comprising these materials should be sufficiently flexible to be able to be bent back upon itself without permanent deformation. The embodiment shown in the drawings further includes washing stations outwardly of the head pulleys 56 where streams of water issue from a pair of jets 98 to cool the belts and wash away any droplets of material. The installation further includes flexible Squeegees 100 which remove beads of water, etc., from the surface of the belts as they traverse the outerruns toward the tail pulleys.

While the invention has been described in considerable detail, I do not wish to be limited to the particular embodiments shown and described and it is my intention to cover hereby all novel adaptations, modifications and arrangements thereof which come within the practice of those skilled in the art to which the invention relates.

Iclaim:

1. In a facility for collection of discrete particles such as fibers and the like: means depositing such materials in a collection zone, nonself-supporting impervious sheet material providing a movable surface having an upper top edge and a portion of which defines a lateral extent of said collection zone, support means positioned in the region over the top edge of said sheet material, means hanging the top edge of said sheet material from the support means, means for moving said sheet material along said support means to change the portion of said sheet material defining the lateral extent of said collection zone, means depositing a fluid binder into said collection zone, and said movable surface having a critical surface tension of wetting that is less than the surface tension of the binder.

2. The material collection facility of claim 1 including -a rigid guide surface spaced outwardly of said collection zone and backing up said sheet material to limit relative movement of said sheet material laterally outwardly of said collection zone and over which said sheet material slides when withdrawn from said collection zone.

3. The facility of claim 1 wherein said critical surface tension of wetting is less than 35 dynes/cm.

4. In a material collection facility: a continuously advancing collection surface, means discharging particles of binder onto said collection surface, an endless belt with one run thereof overlying and generally normal to said collection surface to confine said particles of binder thereon, trolley means positioned over said endless belt, means supporting said endless belt from said trolley means, said binder being a fluid and said endless belt having a binder confining surface having a critical surface tension of wetting that is less than the surface tension of the binder.

5. The facility of claim 4 wherein said critical surface tension of wetting is less than 35 dynes/cm.

6. The facility of claim 4 including: head and tail pulleys tensioning said endless belt, bearing structure joumaling one of said pulleys, a trolley rail over said run of endless belt and supporting said trolley means along said run, a curved section of trolley rail in line with the periphery of said one of said pulleys, means supporting said curved trolley rail from said bearing, said trolley rail and said curved section of said trolley rail having adjacent matching beveled ends, and means for moving said bearing structure lengthwise of said run.

7. The facility of claim 4 including guide means for the edge of said endless belt positioned adjacent said collection surface on the side opposite said surface confining said binder particles, and means for providing a reduced pressure between said guide means and said endless belt.

8. The facility of claim 4 wherein said endless belt is capable of being bent back upon itself without permanent deformation.

9. The facility of claim 4 having head and tail pulleys one of which has longitudinal extending spaced parallel bars for contacting said endless belt and over which said endless belt is sharply bent to flake off material from the surface of said endless belt.

10. The facility of claim 9 wherein said endless belt comprises a reinforcing which supplies the necessary pliability and tensile strength covered by a surfacing material whose critical surface tension is less than the surface tension of said flowable binder.

11. A glass fiber pack producing facility comprising: a continuously advancing foraminous collection surface, an endless belt positioned on an angle to the collection surface, meansv for directing a flow of glass fibers onto said collection surface, means for spraying an aqueous binder solution onto said fibers as they move toward the surface, support means positioned over said endless belt, means hanging the upper edge of said endless belt from said support means, means for moving said endless belt along said support means, guide means for the bottom edge of said endless belt positioned adjacent said collection surface on the side opposite from said binder and fibers, and means for providing a reduced pressure between said guide means and said endless belt to hold said endless belt against said uide means.

12. The g ass fiber pack producing facility of claim 11 having head and tail pulleys at least one of which has longitudinally extending spaced parallel bars for contacting said endless belt and over which said endless belt is flexed sharply to flake off material from the surface of said endless belt.

13. The glass fiber pack producing facility of claim 12 wherein said endless belt comprises a reinforcing which supplies the necessary flexibility and tensile strength by a surfacing material whose critical surface tension of wetting is less than the surface tension of said flowable binder.

14. The glass fiber pack producing facility of claim 13 wherein said surfacing material has a critical surface tension of wetting less than 35 dynes/cm.

15. The glass fiber pack producing facility of claim 11 wherein said flow of glass fibers is accompanied by a gas flow, and said endless belt has a surface exposed to said gas flow having a critical surface tension of wetting that is less than the surface tension of said aqueous binder solution.

16. The glass fiber pack producing facility of claim 15 including guide means for the edge of said endless belt positioned adjacent said collection surface on the side opposite from the binder and fibers, and means for providing reduced pressure between said guide means and said endless belt,

17. In a facility for collection of discrete material such as fibers and the like: means depositing such material in a collection zone defined by sidewalls, a nonself-supporting sheet of a material which forms at least part of one of said sidewalls, means movably supporting said sheet material for endwise withdrawal from said collection zone for cleaning at a location outside said collection zone, means hanging said nonself-supporting sheet material from its upper edge, means blowing air into said collection zone in a manner oscillating said sheet material, means spraying a liquid binder into said collection zone, and said nonself-supporting sheet material having a critical surface tension of wetting that is less than the surface tension of said liquid binder.

Claims

2. The material collection facility of claim 1 including a rigid guide surface spaced outwardly of said collection zone and backing up said sheet material to limit relative movement of said sheet material laterally outwardly of said collection zone and over which said sheet material slides when withdrawn from said collection zone.

6. The facility of claim 4 including: head and tail pulleys tensioning said endless belt, bearing structure journaling one of said pulleys, a trolley rail over said run of endless belt and supporting said trolley means along said run, a curved section of trolley rail in line with the periphery of said one of said pulleys, means supporting said curved trolley rail from said bearing, said trolley rail and said curved section of said trolley rail having adjacent matching beveled ends, and means for moving said bearing structure lengthwise of said run.

11. A glass fiber pack producing facility comprising: a continuously advancing foraminous collection surface, an endless belt positioned on an angle to the collection surface, means for directing a flow of glass fibers onto said collection surface, means for spraying an aqueous binder solution onto said fibers as they move toward the surface, support means positioned over said endless belt, means hanging the upper edge of said endless belt from said support means, means for moving said endless belt along said support means, guide means for the bottom edge of said endless belt positioned adjacent said collection surface on the side opposite from said binder and fibers, and means for providing a reduced pressure between said guide means and said endless belt to hold said endless belt against said guide means.

12. The glass fiber pack producing facility of claim 11 having head and tail pulleys at least one of which has longitudinally extending spaced parallel bars for contacting said endless belt and over which said endless belt is flexed sharply to flake off material from the surface of said endless belt.

13. The glass fiber pack producing facility of claim 12 wherein said endless belt comprises a reinforcing which supplies the necessary flexibility and tensile strength covered by a surfacing material whose critical surface tension of wetting is less than the surface tension of said flowable binder.

16. The glass fiber pack producing facility of claim 15 including guide means for the edge of said endless belt positioned adjacent said collection surface on the side oppositE from the binder and fibers, and means for providing reduced pressure between said guide means and said endless belt.