US 3801243 A
Descripción (El texto procesado por OCR puede contener errores)
[4 1 Apr. 2, 1974 3,551,250 Paoletti......................'....... 425/83 X APPARATUS FOR PRODUCING A MAT lnventors: Harvell Morton Smith; Robert Edward Hengstler, both of Richmond, Ind.
Ferstenberg 425/4 C a H 2 77 99 ll 66 28 34 22 87 33 Primary Examiner-Robert L. Spicer, Jr.
Assignee: Johns-Manville Corporation,
 ABSTRACT A fiber collection system for forming mats of mineral York, N.Y.
1221 Filed: May 16, 1972  Appl. No.: 253,841 fibers by an air felting technique includes a collection chamber between the source of fiber and binder and the collection surface on which the mat is formed All of the walls of the collection chamber are movable I t Cl from the source to the collection surface and are then H advanced incrementally to cleaning stations exterior  Field of Search of the chamber. Belts are employed for the chamber wall surfaces and they are cleaned by a liquid flush and if necessary a scrubber. The walls are mounted so  References Cited UNITED STATES PATENTS that they can be contoured to control fiber flight. Seals enhance the suction control of fiber flight and also function as wall cleaners to deposit debris in the l9/l56.l /155 edge region of the mat which is normally removed and 19/155 crapped 425/4 C 425/4 C 23 Claims, 6 Drawing-Figures Brownlee.....n..,.....
n mmfl n m" n h d 36 m h been CHM i. UMEN 56458 45666 99999 llll ////l 5545 48.58 25464 93483 84378 37 3 22333 PATENTEDAPR 21914 SHEET 2 BF 2 III ill
APPARATUS FOR PRODUCING A MAT CROSS-REFERENCE TO RELATED APPLICATION- This invention complements and employs features of the contoured walls of'the fibercollection chamber disclosed in a patent application of Brian J. Rayle, Lester Fisher and Harvell M. Smith entitled Collection Chamber for Making Mats of Inorganic Fibers which was filed herewith.
BACKGROUND OF THE INVENTION 1. Field of the Invention Mats of mineral fibers have been formed by drawing a stream of gas in which fibers and a binder are entrained onto a collecting surface which: is advanced through a region in which fiber inpinges thereon to progressively accumulate the desired mat thickness. It is common practice to confine the fiber in its flightfrom a fiber dispensing means to the collecting surface. Such confining means has been in the form of walls which enclose the flight path to form a collection chamber which may include side walls and in some instances covering walls partially closing the region from which the fiber is dispensed.
Binder and fibers follow a generally direct path from their sources to the collecting surface. However, some turbulence occurs in the mixing of the streams including the primary stream of fiber and a high temperature, high velocity gas employed to attenuate the fiber in the case of glass, a secondary stream of ambient air of low velocity and another stream of binder, usually an aqueous solution or suspension of athermosetting resin. While a suction behind the fiber collection surface maintains the flight path for the preponderance of the fiber and binder to that surface, eddies are present which cause resin, fibers and resin-coated fibers to impinge upon the walls of the collection chamber. The fiber tends to buildup into wads, some developing as clumps in flight particularly inthe upper portions of the chamber and other as accumulations on the walls. Binder collects in these wads so'that they are carried to the mat in a wet condition. Some fiber remains on the walls for longer periods and buildup. As it remains, it dries and cures. Some of the dried clumps of fiber break off due to the turbulent air flow and cause dry cured wads to collect on the blanket.
The above problems are particularly troublesome where the fiber collection surface is at the bottom of the chamber and are increased further when the source of the primary stream and binder are situated above the fiber collection surface. Gravity then enters into the mechanism delivering the heavy wads to the blanket so that the product quality is reduced by both wet wads and dry wads" which retain their undesirable identity in the final product. Further production is significantly impeded by the frequent shut downs of the apparatus to clean the walls of the collection chamber. Such cleaning involves wash-downs of the chamber walls and, less frequently, a scrape-down of those walls.
2. Description of the Prior Art Heretofore efforts to avoid fugitive fiber contamination of mat product have been undertaken. In R. N. Brownlee U.S. Pat. No. 2,389,024 of Nov. 13, 1945 entitled Means for Forming Fiber Felts a collection chamber is disclosed which is substantially wider than the fiber collection surface upon which fiber and'a binder are directed so that gutters bordering the collection surface receive fugitive fibers which accumulate on and drop from the side walls. In addition, an upper wall and an end wall are faced with moving belt-like conveyors so that fugitive fibers which cling to their surfaces are carried from the container and removed therefrom by a brush. Paoletti U.S. Pat. No. 3,551,250 of Dec. 29, 1970 for Apparatus for Making Uniform Mats of Inorganic Fibers and A. B. Havens U.S. Pat. No. 3,582,432 ofJune l, 1971 for Fiber Mat Forming Hood With Movable Side Walls" disclose fiber collection chambers having side walls made up of vertical slats coupled to present acontinuous side wall surface between a source of a primary stream containing fibers and a foraminous fiber collecting surface. These side wall slats were coupled to form a continuous structure trained over vertical head pulleys and tail pulleys so the wall presented to the collection chamber interior could be advanced out of the chamber and during their return run for readmission to the chamber could be washed and dried. Each of the above structures sought to minimize the buildup of binder and fiber by moving the wall of the collection chamber to a cleaning station.
While the primary objective of these prior art devices was the improvement of product quality by elimination of the random deposition of fiber wad debris on the blanket another significant aspect appeared to have been overlooked. In particular the-lost time due to the need to clean the walls of the collection chamber. Such an objective can be achieved only if all surfaces where fiber can collect and wads can form are cleaned during operation. If surfaces such as the back walls of the chambers are 7 not cleaned when the side walls are cleaned as bya moving wall arrangement, the clean-out time may be reduced but shut downs for periodic cleanings will still be necessary.
Further, the joints and non-contiguous panels with their seams inside the chamber contribute substantially to wad formation.
SUMMARY OF THE INVENTION The present invention relates to fiber collection chambers and more particularlyto such chambers having movable walls arranged to be advanced from the chamber to a cleaning station. It'offers features absent from the prior art including the utilization of moving and cleaned walls for all surfaces where fiber can collect, the form of the walls, the method of their mounting, the cleaning techniques and apparatus, the means of altering wall from a planar construction to enhance fiber distribution, and the seals in the chamber walls.
It has been found that'a relatively continuous surface as a movable side wall presenting no seams to the fiber and binder materially enhances the resistance to the accumulation of fiber, particularly since fiber tends to adhere more readily to even slight discontinuities in the forming chamber wall. Smooth walls facilitate washing.
. The belt surfaces employed are arranged such that the surfaces can be displaced intermediate the extremes of the loop to shape the walls and approximate a Venturi or other form desired from the point of view of enhanced control of fluid flow for the stream entraining the fibers.
An advantageous feature'resides in a vertical loop orientation of the side walls and end walls such that a little or no adverse effect upon the wall belts. These elements arelocated at the bottom of the side walls and perform the-additional function of removing adhering debris in a region where it is readily controlled and disposed of by depositing it on or immediately adjacent the edge of thefiber collector surface in an area that is not controlled as to density 'andthus is removed as scrap.
. BRlEF DESCRlPTlON OF THE DRAWINGS FIG. 1 is a perspective of a fragmentary'and somewhat diagrammatic representation of a collection chamber associated with fiber formers for fiberizing glass and a fiber'collectin'g means for forming a blanket .or mat of glass fibers with only one typical wall cleaning station shown, only one wall belt drive shown and with the wall-to-suction chamber seals omitted;
FIG. 2 is a side elevation of the apparatus of FIG. 1 showing means to control tension and tracking of the side wall belts;
FIG. 3 is across-section of the apparatus of FIGS, .1 and 2 taken at line. 33 of'FlG. 2 and showing a sidewall contour adjusting means;
P16. 4 is a side detail of one form of end wall for'a collection chamber;
FIG. 5 is, a seal construction for the belt side walls showingtheircoupling to the support for the upper flight of the fiber collector surface and the suction chamber walls intermediate the ends of the side walls;
FIG. 6 is a seal construction complementing that of FIG. 5 for the ends of the side walls.
DESCRIPTION oETHE PREFERRED EMBODIMENTS A generally conventional organization of elements for the formation of'fiber mats or blankets byair felting is illustrated in FIG. 1. Molten material ofa suitable inorganic fiberizable material such as. glass is supplied to fiber formers 11 as from a glass furnace (not shown) having aforehearth l2 extending from the furnace to delivery stations forthe fiber formers. Suitable conduits selectively conduct the molten glass to the fiber formers 11 from which it is issued as primary filaments which are intercepted by an attenuating gas blast. For example, each fiber former can be a rotor 14 which is rotated at high speed in a plane generally paralleling a fiber collecting surface 15 so that the molten glass within the rotor spreads in a thin sheet to a perforated wall 17 at its outer annular periphery and. is extruded as primary filaments from the perforations by centrifugal force. An annular flow of gas is directed around the periphery of rotor 14 and toward the fiber collecting surface 15 as from an attenuation burner 18 for eachrotor to intercept the radially extendingprimary fibers and attenuate them while entraining them. Theattenuating gas is at an elevated temperature and is of high velocity so that a primary stream of high-velocity, hot gas 4 and hot filier is developed and-discharged by the combination of each fiber former 11 and its burner 18.
,The primary stream is cooled, a binder is introduced to contact the glass fibers for ultimate bonding of the felted fibers in the mat and the binder coated fibers are directed to the collection surface. A suction chamber 20 imposes a negative pressure between the source of theprimary stream and the fiber collection surface 15 to draw the stream and its entrained fibers toward the collection surface. Perforations in the fiber collection surface pass the gases into the suction chamber 20 behind that surface while the fibers are retained on the face of surface 15 proximate the fiber formers 11. Confining walls extend generally from the vicinity of the fiber formers 11 to the fiber collectionsurface 15 to form a collectionchamber 21. Binder for the fibers, frequently in the form of a fine spray or mist of an aqueous solution or suspension of a thermosetting resin, although a powder form of binder has also been employed as a gas born dispersion, is introduced into the collection chamber.2l as by means of spray nozzles 23 mounted on circular headers 24 which surround the path of the primary stream in proximity to the entry of that stream into the collection chamber.
In order to avoid the buildup of binderand fiber on the walls of the collection chamber 21 those walls are arranged to move in the direction of the primary stream and toward the collection surface and then to be advanced to a cleaning station 26 exterior of the chamber 21. Collection'chamber 21 is comprised of a pair of side walls 27, backwall 29 and front wall30. Each of the walls is made up of a smooth continuous belt looped with a'first bight, 32 for side wall belts 27, 33 for back wall belt 29 and 35 for front wall belt 30, parallel to and adjacent the collecting surface 15. A second bight of each belt defines the limit of its respective wall most remote from' the fiber collecting surface 15 as bights 36 for sidewall belts 27, bight38 of back wall belt 29,'and bight 39 of front wallbelt 30. Belts 27, 29 and 30 are air impervious, seamless and present a smooth surface to -the collection chamber interior. They are of a material which is not adversely affected by the environment of that interior which includes temperature, moisture, and chemical conditions. Further, the surface must be sufficiently resistant to' abrasion that wiping gas seals can be made and maintained and, when utilized, brush cleaning can be applied without significant surface deterioration. One such form of belt is a multi-ply fabric of cotton or polyester having a working face of butadiene N.
In a fiber collection chamber 21 having generally vertical walls extending from downwardly directed sources of primary streams to an underlying, generally horizontal, fiber collection surface 15 the belts 27, 29 and 30 move downward on the inside of the chamber. This allows fiber wads adhering thereto to be scraped off by rubbing against the edge of the blanket of fibers being built up on collection surface 15 so the wads are local ized in the edge region of the blanket normally re t tion surface 15 at the bight 32.
' Cleaning stations 26 can comprise fluid sprays, water in the case of water soluble binders, as from spray header 44 and cleaning brushes 45 with suitable meansfor disposing of the washing fluid and debris as by an underlying trough 47 all located at the lower portion of the exterior run of belts 27, 29 and 30. The run of the belt above the cleaning station provides a drying interval prior to the reintroduction of the cleaned belt into the collection chamber 21.
The general organization of the apparatus illustrated in FIG. 1 is shown in more detail in the other drawings. In FIG. 2 wall belts 27, 29 and 30 are shown trained over rollers as head rollers 48, 50 and 51 in bights 36, 38 and 39 respectively and tail rollers 53, 54 and 56 in bights 32, 33 and 35 respectively. A framework 57 supports the belt rollers for rotation by means of saddle rollers 58 journaled for rotation on the appropriate beams of frame work 57. Tension is maintained for side wall belts 27 by mounting head roller 48 on a beam 59 which is movable with respect to the framework 57 as by means of screw jacks 60 or hydraulic cylinders (not shown). A wide belt such as side walls 27 requires steering means such that it will not be displaced longitudinally of its supporting rollers as it is passed over those rollers or such that any such movement can be corrected. The jacks 60 afford a steering'means since the roller inclination can be adjusted by adjustment of jacks 60 at one or both ends of beam 59. A sensor 61 such as a radiant energy sources opposite radient en- 'ergy detectors at an edge of, the belts can detect belt displacement along the rollers and control the steering mechanism automaticallythrough electrical or electrohydraulic control for the jacks.
End wall rollers can be arranged as side wall rollers with support beams and jacks corresponding to beams 59 and jacks 60 for tension and tracking control and can be controlled by sensors corresponding to sensors 61. In the case of back wall belt 29 this correspondence is utilized and a cleaning station (not shown) corresponding to the side wall station 26 is utilized. In the case of the front wallbelt 30 it is desirable to provide substantial latitude in the location of the bight 35 since it provides a seal against the free upper face of the mat or blanket advanced from the collection chamber 21 by fiber collecting surface 15. Accordingly, a pair of takeup rollers 62 and 63 are arranged so that roller 62 can be shifted vertically to-accommodate changes in the separation of rollers 51 and 56. It is also desirable to assure that no debris falls from the cleaning station 64 for front wall belt 30 since the mat product is passed beneath that station. Accordingly, as best seen in FIG. 4, the cleaning station 64 is located on the upper run 66 of belt 30 so that trough 67 can be located below takeup roller 63 to catch any debris which runs down the face of upper run 66.
While the side walls can be moved intermittently, it-
As noted in the aforenoted Rayle et al patent application, fiber flow can be improved by shaping the walls of a collection chamber between the source of the primary stream including entrained fibers and the fiber collection surface. Such improvement includes: a centering of the primary stream and its augmenting streams and reduction of the tendency for the stream to follow a wall; reduction of turbulence particularly as developed at the interfaces between the high velocity primary stream, the low velocity inspirated ambient air and the intermediate velocity binder spray; control of the mixing of the cooling ambient air with the primary hot gas-fiber stream and the introduction of binderto the entrained fibers; and more uniform distributin of the fibers across the fiber collecting surface 15. A preferred contour is generally that of a Venturi wherein the streams are introduced at a wide mouth, converge to a throat region and diverge from the throat region to the fiber collection surface. FIGS. 1 and 3 illustrate belt sidewalls contoured in the manner of the Rayle et al. 1
disclosure. A throat region 73 is defined by a roller 75 mounted for rotation on a movable base 76 by means of saddle rollers 78. The'throat width and height can be adjusted since base 76 can be adjusted in elevation by screw jacks 79 or their equivalent and in their transverse spacing from the opposite roller 75 by similar means 81. It should be noted that the three position suspension of the side wall belts 27 produces an essentially planar wall region between rollers 48 and 75 defining a converging section 82 of the chamber, however the negative pressure produced in the suction chamber 20 and communicated to the lower portion of the collection chamber 21 causes the side wall belt runs between rollers 75 and 32 defining a diverging section 84 to bow inward forming a curved side wall of the form found advantageous byRayle et al. Further the adjustability of the height and width of the roller "75 defining throat region 73 enables the flow patterns to be adjusted in operation.
- In order that the suction in the suction chamber 20 be effective in the collection chamber 21 and be effective across the fiber collection surface 15 to lay down a uniform fiber blanket, spurious gas flow should be minimized. The corners of the collection chamber 21 are closed by mounting the planar run of the front and back wall belts 30 and 29 so they are proximate to and parallel the straight edges 85 of the side wall belts 27. The slight leakage experienced in these corner regions with this arrangement has been found acceptable. At
the intersection of the side wall belts 27 with the fiber collection surface 15, it has been found that a more effective seal is desirable since excessive flow-in that region distorts the fiber distribution on the collection surface.
The collection surface 15 is arranged to be advanced through the collection chamber 21 from the back to the front end of that chamber. One arrangement for providing an effective seal between the suction chamber 20, the belt side wall 27 and the fiber collection surface 15 is shown in FIGS. 5 and 6. Surface 15 is made up of a series of coupled flights 86 each having a perforated deck 87 to pass the gases in collection chamber 21 to suction chamber 20. A frame 89 is secured to deck 87 beneath the collection surface 86 and is secured to links 91 of a roller chain having rollers protruding from the frame 89. Rollers 90 support their respective flights 86 at their four corners by riding upon rails 92 secured to the structure of suction chamber 20 and extending along the path of travel of the flights across the open top of chamber 20. Lateral guidance of the flights is provided by a side rail 93 engaged by a guide shoe or roller 94 extending from the ends of frame 89 of each flight. The adjacent flights 86 are coupled together by links 91 of the roller chain to make a continuous loop which is carried from tail sprocket 95 across the rails 92 spanning the open suction. chamber top to head sprocket 97 and returnedby sprockets 98 and 100 carrying the flight beneath the suction chamber, a takeup roller or sprocket 101 is shown to accommodate variations in length of the closed series of flights. One of the chain sprockets can be driven by a suitable means such as a variable speed drive and electric motor (not shown).
i A continuous seal strip 42 of a resilient, flexible material is secured to the sides of the flight flames 89 and a seal flap 104 is formed by turning strip 42 back upon itself to wipe the face of the side wall belt 27 with a sealing engagemenLThis wiping action also removes debris from the belt and deposits it on the edge 106 of the blanket of fibers accumulated on deck 87. A second sea] from the margin 107 of the open top of suction chamber tothe bight 32 of side wall belt 27 is afforded by a seal strip 41 having a self biasing flap 110 bearing against the belt 27 and wiping its surface when it is turned by the advance of the belt around roller 53.
The ends of the bight 32 and roller 53 for each side 7 wall are sealed byblocks 111 conforming to the bight.
These blocks also are resilient and as the seal strips, are of a material which does not impose appreciable wear on the side wall belt. The blocks fit between the side rail 93 and the margin 107 of the chamber and abut the ends of seal strip 41. The edge 1 12 of flap 104 bears on and wipes longitudinally across the upper face 114 to close the path from the suction chamber as the flights pass the seal blocks 111.
The present arrangement provides for all interior surfaces, sides, front, and back to be continuously moved external of the chamber 21, cleaned and returned to the chamber in order to eliminate the need to shut down for cleaning the fiber collecting area. The belt cleaning process has been found effective under varying conditions. Except under extreme conditions, if the belts are continuously advanced it has been found that no fiber adheres to the belts. This is attributed to the apparent requirement that a dwell time is required for a resin binder film to accumulate and initiate a cure whereas the wiping of the belt side walls on the blanket of fibers and by the seals prevents such buildup. In the absence of binder the fibers which do contact the walls do not adhere but continue their flight to the collecting surface 15. Where some binder tends to accumulate, a water wash is ordinarily sufiicient to remove it and prevent fiber adhesion. Only under the most severe conditions has it been necessary to employ both a wash and brush cleaning. Thus when the belt walls were permitted to remain stationary for long intervals (hours) they could be restored to a fully cleaned condition bywashing and brushing. I e
It will be noted that an orientation of the brush 45 preceding the spray 44 is disclosedfor the side wall cleaning station while the front end wall cleaning station reverses that order. Generally, the brush is most effective to remove fiber, hencefor light accumulations the spray can precede the brush while with heavy accumulations it is desirable to sweep away as much fiber as possible before washing the binder. in some applications where the belt surface is not dried sufficiently prior to its return to the collection chamber interior a squeege to wipe the surface and/or a drying blower can be employed.
It is to be understood that the above disclosure is intended to set forth the principles of the invention and that variations in the arrangement of parts and the elements to achieve those principles can be made without departing from its spirit or scope. Accordingly, the description and drawings are to be read as illustrative and not in a limiting sense.
What is claimed is:
1. Apparatus for producing a mat of mineral fibers bonded by a binder comprising: a fiber collection surface adapted to define one major face of said mat; means discharging mineral fibers and a binder forming material in a direction to impinge upon said fiber collection surface; a plurality of endless wall mechanisms each extending from the vicinity of said discharging means to a margin of said fiber collection surface and defining a chamber, said plurality of endless walls each having a surface portion defining an enclosed path from the vicinity of said discharging means tosaid fiber collection surface, drive means to advance each of said endless wall mechanisms to change the surface portion of each of said endless wall mechanisms defining the enclosed path and an adjustable guide means associated with at least one endless wall mechanism for controlling the width of said chamber.
2. Apparatus according to claim 1 wherein said plurality of wall mechanisms comprise two opposed pairs of said mechanisms.
3. Apparatus according to claim 1- wherein at least I two of said wall mechanisms have opposed surfaces and wherein said drive means includes means for driving the opposed surfaces of said opposed mechanisms to advance the opposed surfaces from said discharging means toward said fiber collection surface.
4. Apparatus according to claim 1 wherein said endless wall mechanisms each are a seamless belt presenting a smooth surface proximate said discharged fibers and binder.
5. Apparatus according to claim 1 wherein said endless wall mechanisms each are a belt; and wherein a first roller for ach of saidmechanisms, around which said belt of said respective mechanism is carried, is
mounted for rotation with its axis parallel to and proxi 7. Apparatus according to claim 6 including steering means for steering one of said belts so that said belt is maintained on a desired track on the first and second rollers of said respective mechanism.
8. Apparatus according to claim 7 wherein said steer ing means includes means to sense deviations from the desired trackof said belt and drive means responsive to said sensing means to maintain said belt in said desired track. I
9. Apparatus according to claim 1 including a cleaning station for each of said endless wall mechanisms external of said enclosed path and effective to clean the surface ofsaid respective mechanisms defining said enclosed path.
10. Apparatus according to claim 9 wherein said endless walls are belts, said collection surface is horizontal and said discharging means is above said collection surface, including: a first roller for each of said mechanisms around which said belt of said respective mechanism is carried and which is mounted for rotation with its axis parallel to and proximate to said collection surface; a second roller for each of said mechanisms around which said belt of said respective mechanism is carried and which is mounted for rotation with its axis parallel to the axis of said first roller of said respective mechanism and proximate to said discharging means; means to advance said collection surface from within said enclosed path defined by said endless walls and beneath one of said wall mechanisms; a third roller for said one wall mechanism having an axis extending parallel relative to said axis of said first and second rollers thereof and adapted to guide a run of said wall mechanism in alignment with said first and second rollers, a fourth roller offset from said alignment of said first and second rollers and said third roller; a second run of said wall mechanism from said fourth roller to said second roller, said cleaning station being located to clean said second run; and a drip shield beneath said fourth roller to prevent debris cleaned from said second run from dropping onto said mat as it is advanced on said collec tion surface.
11. Apparatus according to claim 3 wherein said opposed surfaces of said endless wall sections are flexible, and wherein said guide means contours said opposed surfaces between said discharging means and said fiber collection surface.
12. Apparatus according to claim 11 wherein said guide means form a converging region for said opposed walls in the vicinity of said discharging means which converges toward said fiber collection surface, a diverging region for said opposed walls in the vicinity of said fiber collection surface which diverges toward said fiber collection surface, and a throat region between said opposed walls which extends between said converging region and said diverging region.
13. Apparatus according to claim 12 wherein said opposed walls are belts; and including for each opposed wall a first roller around which said belt of said respective wall is carried and which is mounted for rotation with its axis parallel to and proximate said collection surface; a second roller around which said belt of said respective wall is carried and which is mounted for rotation with its axis parallel to the axis of said first roller of said respective wall and proximate to said discharging means; and wherein said guide means is a third roller around which said belt of said respective wall is carried and which is mounted for rotation with its axis parallel to, between, and offset toward said opposed wall from the axes of said first and second rollers of said respective wall.
14. Apparatus according to claim 11 wherein means is provided for adjusting the location of said guide means in a region between said discharging means and said fiber collection surface whereby the contour of said opposed surfaces is adjustable.
15. Apparatus according to claim 13 wherein means is provided for adjusting the location of said third rollers normal to their axes whereby the contour of said opposed surfaces is adjustable.
16. Apparatus according to claim including means for developing negative gas pressure on the side of said collection surface opposite said wall mechanisms, said collection surface being permeable to gas; and a gas seal from said collection surface to at least a pair of said belts.
17. Apparatus according to claim 5 including a chamber having an opening adjacent the side of said collection surface opposite said wallmechanism; said collection surface being permeable to gas; means for developing a negative gas pressure in said chamber; and a gas sea] from a margin of said chamber opening to a bight of said belt defined by said first roller.
18. Apparatus according to claim 16 wherein said collection surface is movable parallel to the axis of rotation of said first roller and said seal is a flexible, resilient flap of gas impermeable material flexed between and biased against said collection surface and a bight of said belt defined by said first roller.
19. Apparatus according to claim 17 wherein said seal is a flexible, resilient flap of gas impermeable material flexed between and biased against said chamber opening margin and a bight of said belt defined by said first roller.
20. Apparatus for producing a mat of mineral fibers bonded by a binder comprising: a fiber collection surface having a length and a width and adapted to define one major face of said mat, said surface being movable along a path parallel to its length; means discharging mineral fibers and a binder forming material in a direction to impinge upon said fiber collection surface; a pair of opposed endless wall mechanisms bounding a region from the vicinity of longitudinal margins of said fiber collection surface to the vicinity of said discharging means, said endless walls of said mechanisms being flexible; and guide means engaging a portion of at least one of said endless walls intermediate the vicinity of said fiber collection surface and the vicinity of said discharging means to displace said intermediate portion of said endless wall out of a plane common to portions of said endless wall at said vicinity of said collection surface and said vicinity of said discharging means.
21. Apparatus according to claim 20 wherein said opposed walls are each engaged by said guide means and said intermediate surface portion engaged by its respective guide means is displaced toward the opposed wall whereby the opposed surfaces bounding the region between said collection surface and said discharging means have contours which locally narrow said region.
22. Apparatus according to claim 20 including means to adjust the position of said guide means to adjust the contour of said respective region bounding surfaces of said endless wall.
23. Apparatus according to claim 20 wherein said wall mechanisms each include a seamless, smooth, gas impermeable belt bounding said region; a first roller mounted for rotation about a longitudinal axis parallel to and in the vicinity of one of the longitudinal margins of said fiber collection surface to guide a bight of said belt; a second roller mounted for rotation about a longitudinal axis parallel to the axis of said first roller and in the vicinity of said discharging means at one side of said region to guide a second bight of said belt; and a third roller mounted for rotation about a longitudinal axis parallel to the axis of said first and second rollers of said respective wall mechanism and positioned inward of said region from a plane through the axes of said first and second rollers to guide a third bight of said belt and contour said wall inward of said region between said first and second bights.