US3551250A - Apparatus for making uniform mats of inorganic fibers - Google Patents

Description

Dec. 29, 1970 J. PAOLEYTTI 3,551,250

APPARATUS FOR MAKING UNIFORM MATS OF INORGANIC FIBERS Filed D80. 29, 1967 2 Sheets-Sheet l SUCTION BOX 0: 5 g g. E a; f

I N VENTOR.

ATTORNEYS FOEE/PT J. P404 77/ D 9. 1970 R. J. PAQLETTI APPARATUS FOR MAKING UNIFORM MATS OF INORGANIC FIBERS 2 Sheets-Sheet 2 Filed Dec. 29, 1967 lll INVHNTOR F05 (Z P404 [77/ QUMMM RNEYS United States Patent O APPARATUS FOR MAKING UNIFORM MATS F INORGANIC FIBERS Robert J. Paoletti, Toledo, Ohio, assignor to Owens- Corning Fiberglas Corporation, a corporation of Delaware Filed Dec. 29, 1967, Ser. No. 694,582 Int. Cl. B29j 5/00; B32b 5/16; DZlb 1/04 US. Cl. 15637 0 7 Claims ABSTRACT OF THE DISCLOSURE A mat of inorganic fibers is made by sucking an air stream carrying glass fibers and a spray of organic binder down upon the top surface of a foraminous conveyer. A suction box is positioned below the conveyer to draw the material onto the top of the conveyer and the fibers and spray are confined to the top surface of the conveyer by a forming hood. The side walls of the forming hood comprise a pair of parallel endless conveyers having adjacent flights which form opposite vertical side walls of the hood. The adjacent conveyers have vertical head pulleys positioned adjacent the tail pulley of the horizontal conveyer and have tail pulleys spaced in the direction of the movement of the horizontal conveyer from its tail pulley. The conveyer elements of the adjacent flights extend generally vertically and travel in the opposite direction to the horizontal conveyer. The elements of the parallel conveyers have smooth surfaces and are hinged together below these smooth surfaces so that the elements separate as they move around the head pulleys. A flow of wash water flows over and between the elements as they round the head pulley, and an end wall extends between the adjacent flights in the direction of the horizontal conveyer movement from these parallel head pulleys. After the parallel conveyer elements round their head pulleys they are squeegeed to remove the water as they travel to their tail pulleys, following which they again move into position to form hood walls which direct the fiber and binder down upon the horizontal conveyer. The vertical conveyer elements are spaced a slight distance from the top surface of the horizontal conveyer, and the lower back sides of these conveyer elements ride along a side of a longitudinally extending board positioned just above the top surface of the horizontal conveyer outside of the forming area. The wash water is recirculated a number of times, and a side stream enriched with the binder removed from the parallel conveyers is fed to the binder mix tanks and used to form part of the binder solution.

BACKGROUND OF THE INVENTION Prior to the invention, mats of mineral fibers that are bonded together by an organic binder have been made by pulling the minarl fibers into a forming hood that is positioned over a horizontal conveyer. The fibers are carried along in a large volume of gases into which a binder is sprayed, and the fibers and spray which are fed to the forming hood are sucked down upon the conveyer by a suction box positioned beneath the top surface of the horizontal conveyer. The fibers are attenuated and carried along by a large volume of these turbulent gases, so that the fibers and the spray impinge upon the walls which form the forming hood. The walls forming the forming hood have for the most part been stationary, and some of the wetted fibers collect on the walls of the forming hood where they stick for a period of time. Some of these fibers fall down onto the surface of the mats being formed as wads of fibers, and others remain on the side walls of the forming hood until the equipment is shut down and cleaned. The wads of glass fibers which fall off of the 3,551,250 Patented Dec. 29, 1970 walls of the forming hood are often wetter than the fibers on the surface of the conveyer, and these wads leave imperfections in the mat being formed. Not only are these wads not integrated well with the rest of the fibers of the mat, but their binder composition is different from that of the mat, so that when the mat containing the wads is cured in an oven, they visually stand out as an imperfection.

In one instance with which applicants are aware, the side walls of the hood move in the same direction and speed as the horizontal conveyer to create a minimum of disturbance of the side edges of the mat. Long flat metal plates have been laid upon the top surface of the horizontal conveyer to act as a seal, and the bottom of the vertical side walls have slid along on top of the steel strips. The movable side walls have been moved forwardly around head pulleys, washed with water, and then moved back to the beginning of the horizontal conveyer. Mats formed by such apparatus have not achieved uniformity, and it has not been known what has caused the imperfections.

An object of the present invention is the provision of a new and improved apparatus for making bonded mats of inorganic fibers which is devoid of wads and blemishes that are discernible to the naked eye.

SUMMARY I It has been discovered that a more uniform mat of randomly oriented inorganic fibers bonded together at points of contact by a binder can be made in apparatus wherein the fibers are collected on a horizontal conveyer between side walls which move in the opposite direction from that of the horizontal conveyer. The mat has less binder spots and Bakelite spots, and the cure of the binder throughout the mat is more uniform. In the preferred embodiment, a transverse vertical wall is positioned between the movable vertical side walls adjacent the beginning of the top flight of the horizontal conveyer, and the transverse wall is preferably slightly out of contact with the movable side Walls. Any material adhering to the movable side Walls usually passes the transverse wall and moves around a head pulley of the conveying mechanism forming the vertical side walls where a flow of water downwardly over the movable walls washes debris therefrom, following which the vertical walls are dried. It appears that this procedure generally eliminates the binder spots and Bakelite spots adjacent the edges of the mat which is formed by the apparatus; and it also appears that the binder cure across the width of the mat is more uniform. The movable vertical side walls preferably also have an air space or clearance between their bottom edges and the top surface of the horizontal conveyer to allow a slight controlled air flow therebetween which has a beneficial effect upon the uniformity of the edges of the mat which is produced. The apparatus appears to remove a large proportion of the wads of fiber and binder which normally form binder spots and Bakelite spots from the forming area. The wads are washed off of the walls and the binder is leached out of the wads. This wash water is recirculated a number of times and a side stream is used to make fresh binder solution. The binder in the side stream has no appreciable advance in the cure of the resin, so that the binder which previously formed Bakelite spots is now uniformally distributed throughout the mat. The mat which is produced has more uniform moisture content and more uniform cure throughout than do mats made by prior art apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of apparatus embodying principles of the present invention; and

FIG. 2 is a fragmentary plan view of the structure which forms the immediate mat forming area of the apparatus shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus shown in the drawings for producing mat generally comprises a glass furnace having a forehearth 12 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 shaft 20 and a centrifuge basket 26 having a plurality of openings in its other periphery is fixed to the bottom end of the hollow shaft 20. A plurality of molten streams of glass are thrown from the openings in the basket 26, and a downwardly 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 of the present invention will include a multiplicity of veil producing mechanisms 14 and four are shown in FIG. 1.

The glass fibers from the various veils 28 are collected on the top foraminous flight 30 of a horizontal conveyor 32 having a head pulley 34 and tail pulley 36. A suction box 38 is positioned beneath the top flight 32 to draw the large volume of gases downwardly through the top flight 30 and cause the fibers in veils to be deposited on the top surface of the conveyor 30 in the form of a mat 40. The swirling volume of gases and fibers which constitute the veils 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 of the conveyor 30. In the embodiment shown, the fibers and gases are confined to the top surface 30 by a pair of parallel side walls 42, a stationary rear end wall 44, a front end wall 46, and roll gate 48.

The mat of loose fibers that is formed within the confines of the walls above described (hereafter called forming hood), is bonded together by a binder that 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 mat. Droplets of the binder solution are held at crossover points of the fibers forming the mat, and the binder impregnated mat 40 is delivered to a cure oven 52 where the water is removed and the binder cured to a thermostat condition. In the present instance, the binder which is used is 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 bottom edge of the front end wall 46 to generally seal off the forming hood and smoothen out the fibers issuing from the forming hood.

The veil that is formed by the apparatus 14 does not have a uniform distribution of the glass fibers and includes wads of these fibers which became saturated with binder and were thrown against the side walls of the forming hood. Prior to the present invention, stationary side walls have been used, and it has been necessary to shut down the mat making apparatus above described periodically, to clean off an accumulation of the wads of fibers and binder that adhere hereto. Prior to the present invention, this has been accepted as a necessary part of the operation of forming mat. The prior art was also aware of the fact that the mat produced by the apparatus was nonuniform and contained what is called binder spots and Bakelite spots. Binder spots are areas which are incompletely cured, and Bakelite spots are areas which have more than an average amount of binder and which is fully cured, Because the area within the forming hood is extremely turbulent, however, the prior art did not know how the prevent the formation of binder spots and Bakelite spots, since their formation could not be visually observed. The apparatus of the present invention produces mat which is considerably more uniform than has been produced by the prior art, and by observing its operation the reasons for binder spots and Bakelite spots in the prior art are now apparent. In the prior art, the binder spots and Bakelite spots were most numerous adjacent the side edges of the mat and it is postulated that these imperfections were formed by wads of binder impregnated fibers which had previously adhered to the side walls of the forming hood and which were loosened by the turbulent gases to cause the wads to fall down onto the mat adjacent the side edges of the mat. I11 one instance, the side walls of the forming hood were made to move along with the top flight 30 of the horizontal conveyor, and in this instance the binder spots and Bakelite spots still existed. I

In the present instance, the parallel side walls 42 are formed as part of endless conveyors 54, the adjacent parallel flights 42 of which move in the direction opposite from that of the top flight 30 of the horizontal conveyor 32. As such, the movable side walls 42 rub against the side edges of the mat being produced, but it has been found not to tear or unduly damage the side edges of the mat.

Each of the endless side wall conveyers 54 are formed from a plurality of vertical elements which are fastened to and are carried by top and botom roller chains which move about sprockets forming head pulleys 56 and tail pulleys 58. The sprockets forming each tail pulley 58 are connected together by a shaft 60, and each shaft 60 is in turn driven by motor and gear reducer 62, only one of which is shown. The endless side wall conveyers 54 are constructed in such a way that the space between the verticle conveyer elements open up, or become enlarged as they round the head pulley 56 to loosen 'and expose any debris accumulated therein. The debris between the vertical conveyer elements is washed from the side wall conveyers by wash nozzles 64 which project a stream of water against the top edge of the respective side wall conveyer outwardly of the end wall 44 as the vertical elementsround the head pulley 56. The flow of wash water issuing from the nozzle 64 washes wads and other debris downwardly into a recovery pan 66 from which the wash water flows to a separator 68 which removes the glass fibers. The wash water is recirculated by a wash water pump 70 to the nozzles 64. The binder that is removed from the wads and from the side walls becomes dissolved in the wash water and a side stream of the Wash water is pumped by pump 72 to a binder preparation tank 74 where it is used to formulate the aqueous binder solution. The aqueous binder solution is in turn pumped by pump 76 to the binder nozzles 50 previously described. After the vertical conveyer elements are washed by the flow of water from the nozzle 64, the vertical elements move forwardly to a squeegee 78 positioned at an angle to force the water downwardly into the recovery pan 66. The squeegee 78 is located adjacent the head pulley 56 and any water that remains after the squeegee operation, has an appreciable time to evaporate before the elements round the tail pulley to move into position in the forming hood.

The apparatus above described has advantages which at first may not be apparent. In comparing the mat which it produces from that of the prior art, it is noted that the mat has less binder spots and Bakelite spots. It is believed that binder spots and Bakelite spots were caused by wads of fiber and binder falling from the side walls onto the side edges of the mat. In the apparatus of the present invention, it will be seen that those wads which stick onto the wall are not removed by a wiping action of the rear end wall 44, but that clearance is provided to allow the wads to move out of the forming area Where they are washed free of the vertical conveyer elements. The wads are washed into the recovery pan where the binder is leached therefrom, and this occurs so quickly that the binder does not have a chance to advance in cure from its A stage. The binder, therefore, can be recirculated and used over again without harmful effects. In some instances, there will be a rush of air into the forming hood through the clearance between the rear end wall 44 and the movable side walls 58 which will cause some of the wads to fall down upon the conveyer mat. With the apparatus of the present invention, these wads will be one of the first materials that are collected on the horizontal conveyer 30 and can have excess binder removed therefrom due to the increased length of travel over the suction box. In addition, the bulk of the glass fibers forming the mat, fall on top of the wads so that the wads become more thoroughly integrated and can not be seen from the top surface of the mat which is formed. It will also be seen that the front wall 46 in the present instance does not wipe wads from the movable side walls as might occur if the side walls moved in the same direction as the horizontal conveyer 30. It will further be seen that optimum conditions are provided by the washing of the movable side walls adjacent the head pulleys 56 rather than at the tail pulleys 58, since the wash water has no chance of falling on the side edges of the mat as would occur if washed at the tail pulleys 58. Wash water on the mat would, of course, leach binder from the mat and give areas which were depleted of the binder.

It will now be apparent that the objects heretofore enumerated as well as others have been achieved, and that there has been provided a new and improved apparatus which produces more uniform mat for reasons which are now apparent by observation of the highly turbulent gases and fiber fed into the forming area.

While the invention has been described in considerable details, we do not wish to be limited to the particular embodiments shown and described, and it is our 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.

I claim:

1. Apparatus for producing a mat of mineral fibers Wetted by a binder with the width of the mat being many times greater than the thickness of the mat, said apparatus comprising: a pair of generally vertical endless wall mechanisms having adjacent generally parallel runs positioned apart by a distance corresponding generally to the width of the mat, a generally horizontal movable fiber collection surface extending transversely to said runs to define one major surface of the mat, said fiber collection surface moving in one endwise direction of said runs, means discharging mineral fibers and a liquid binder forming material between said runs and onto said fiber collection surface to continuously add increments of fibers to build up the thickness of the mat normal to its major surface, and means moving said runs in the opposite endwise direc- 6 tion from the direction of movement of said fiber collection surface.

2. The apparatus of claim 1 wherein said runs move to a turn around region located at the upstream end of said fiber collection surface.

3. The apparatus of claim 2 including Washing means for said vertical endless wall mechanisms located at the upstream end of said mechanism.

4. The apparatus of claim 3 including binder distribution means for distributing a binder in a water vehicle to said fibers, collection means for water vehicle delivered to said washing means after it has Washed the vertical endless wall mechanism, means for preparing binder distributed throughout the water and delivering it to said binder distribution means, and means delivering the water and binder from said collection means to said binder preparation means.

5. Apparatus for producing a mat of glass fibers wetted by a binder with the Width of the mat being many times greater than the thickness of the mat, said apparatus comprising: a pair of generally vertical wall mechanisms with one mechanism having a run positioned adjacent to and facing a corresponding run of the other mechanism and with at least a portion of said facing runs being parallel, said generally parallel runs being positioned apart by a distance corresponding generally to the width of the mat, a movable fiber collection surface extending transversely to said parallel portions of said runs to define one major surface of the mat, said fiber collection surface moving in one endwise direction of said runs, means discharging said fibers and an aqueous solution of a binder between said runs and onto said fiber collection surface to continuously add increments of fibers to build up the thickness of the mat said runs in the opposite end wise direction from the direction of movement of said fiber collection surface to a turn around region, and washing means for said vertical endless wall mechanisms.

6. The apparatus of claim 5 wherein said endless wall mechanisms include vertical wall flights arranged to move apart as they round said turn around regions.

7. The apparatus of claim 6 wherein said'washing means applies wash water to said vertical wall flights when moved apart, said apparatus further including: means for collecting the wash Water from the vertical wall flights, and means recirculating the wash Water from said collection means to said binder spraying means.

References Cited UNITED STATES PATENTS 9/1943 Drill et a1. l56-372X 6/1950 Joa l9l56X U.S. Cl. X.R. 156-372; 264-l1 5

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