Abstract:
A spinner adapted to produce a dual glass fibre component insulation product; said spinner including a plurality of horizontal baffles adjacent to a spinner peripheral wall; said baffles separating two molten glasses of differing coefficients of thermal expansion and providing mechanical strength and resistance to reduce deformation of said spinner.

Description:
[0001]    General field of this invention is a method and apparatus for manufacturing dual-component fibers from thermoplastic materials, such as glass or some other mineral or polymer materials, by using a rotary fiber forming process. More particularly this invention belongs to a category of devices for centrifuging dual-component curly glass fibers, where the fibre curl is the result of distinct differences in some physical properties or parameters of the two separate glasses. A most common approach is to utilize two unique glass formulations with a significant difference in their coefficients of thermal expansion.  
           [0002]    Typical glass fibre thermal or acoustical insulation product is made of rather short, single glass and basically straight glass fibers. Common method of manufacturing these glass wool type fibers is a rotary fiberizing process, where a single molten glass composition is forced by a high speed rotation through the orifices in the peripheral wall of a centrifuge, usually referred to as a spinner, and is further subjected to the combined action of a high temperature flame and low temperature/high velocity compressed air blasts.  
           [0003]    It has been recognized some forty years ago that curly or non-straight glass fibre geometry should in principle offer many insulation product advantages. Some of these highly desired product attributes include: substantially higher allowable product compression ratio, offering substantial cost savings in product storage and transportation (distribution), also in packaging materials; better volume filling ability; lower dust level; less itch; potential for much lower organic binder level required to assure product integrity, lower binder cost; reduced organic emissions. One can also reasonably expect a slightly higher product thermal resistance, meaning possibility of increased earnings due to consequential density reductions. All of these expectations, to a varying degree, have turned out to be true.  
           [0004]    The very first attempts to make curly glass fibre were made by Owens-Corning in the 60&#39;s. Slayter et al. in U.S. Pat. No. 2,927,621 discloses the production of curly glass fibers by passing a continuous single glass composition fibre through opposed contoured skirts. However, this thick and long fibre is unsuitable for insulating products. Tiede in U.S. Pat. No. 3,073,005 discloses a non-rotary fiberizing process for making bicomponent curly glass fibre; two glasses with differing thermal expansion coefficients are put into side by side contact. This bicomponent curly fibre was not meant to be used for insulation products. Some other patents disclosing methods of making curly or kinky glass fibers are disclosed in U.S. Pat. Nos. 3,236,616 and 4,145,199, but still these methods are not that practical for making insulation product.  
           [0005]    It is generally accepted that a non-rotary fiber forming process can not effectively compete with the rotary one for the economic manufacture of a typical glass fibre insulating product, because of a substantially lower throughput capacity and too coarse fibre to make a good glass wool. As a consequence, some methods of imparting kink by pulling fibre from a textile bushing and mechanically crimping it by passing fibre, while still in a hot state, through a series of opposed intermeshing gears are not a viable option.  
           [0006]    Stalego in U.S. Pat. No. 2,998,620 discloses a rotary method for making bicomponent curly glass fibers, where two glass compositions differ in thermal expansion coefficients. There is no mention of using these curly fibers for insulation products.  
           [0007]    In 1995, Owens-Corning obtained patents for a new technology of manufacturing bicomponent curly fibre by a rotary fiberizing technique. The clear objective was to use this fibre for thermal insulation products. The scope of patenting is wide, including process, apparatus and product. Some other major manufacturers of fibre glass insulation (Isover Saint Gobain and Johns-Manville) were also granted some patents in this field.  
           [0008]    A typical approach to manufacture curly bicomponent glass fibre by a rotary fiberizing, is to use two glass formulations with widely different coefficients of thermal expansion; and then feed these two glasses as separate glass streams, in a radially displaced configuration, into some sort of integrated glass distributor inside a spinner assembly; force first and second glasses into alternate vertical compartments circumferentially spaced around the interior of the spinner peripheral wall, and finally centrifuge these two glasses through orifices drilled in the spinner peripheral wall along the adjacent compartments dividing line such that the two glasses join each other in side to side contact before emerging from a single orifice as a bicomponent fibre.  
           [0009]    Clearly, there is a need for increasing throughput capacity of these dual-glass spinners; U.S. Pat. Nos. 5,468,275, 5,474,590 and 5,595,766 disclose some possible ways of addressing the capacity issue by using elongated orifices, slanted rather than vertical glass compartments and multiple exits for each inlet, respectively.  
           [0010]    Some other areas of concern in the development process of highly effective and practical dual-glass spinner designs include some aspects of strengthening spinner structure by using some more specialized alloys and spinner forming methods (U.S. Pat. No. 5,743,157). Modified spinner geometries are adapted for radial balancing during the centrifuging operation, and as such less prone to thermally induced spinner geometry deformations (U.S. Pat. Nos. 5,582,841 and 6,167,729 B1), and simplified fiberizing orifice configurations, i.e., replacing a typical Y- or V-shaped hole configurations with radially drilled ones. These are less expensive to drill, offering reduced hole wear and extended dual-glass spinner service life (U.S. Pat. No. 5,987,928).  
           [0011]    The object of the present invention is to provide a dual-glass spinner for manufacturing quality bicomponent curly glass fibre at high production rates, i.e., at a throughput capacity in principle comparable with that for a standard single-component spinner of the same diameter.  
           [0012]    The present invention approach to deal with the dual-glass spinner fiberizing throughput issue is to use horizontal rather than a vertical arrangement of glass compartments on the inside of the spinner peripheral wall, and combine it with a unique hole drilling concept, so the resulting dual-glass hole pattern, as seen on the spinner face from the outside, is basically the same staggered, dense and uniform hole pattern as for a single-glass spinner; both in general appearance (excluding the exit orifice somewhat oval shape) and the total number of holes per spinner (spinner hole count).  
           [0013]    Horizontal flanges or baffles serve also as effective stiffeners or stiffening ribs, adding some mechanical integrity and extra strength to the dual-glass spinner structure, particularly against spinner face deformation.  
           [0014]    Clearly, in the present invention, there are numerous possibilities. Generally speaking two major paths emerge, namely: use bicomponent curly fibre alone, or in a combination with some other fibre(s), not necessarily glass fibre.  
           [0015]    Owens-Corning manufactures attic and crawlspace thermal insulation. This is a binderless, plastic sleeve enclosed product, entirely made of bicomponent curly Miraflex(*) glass fibre. There are also U.S. patents disclosing thermal insulation products being a blend of straight single-glass and curly dual-glass fibers, cf. U.S. Pat. No. 5,968,645.  
           [0016]    A mixture of single-glass straight fibre with a dual-glass curly fibre can be made off-line, particularly for a loose-fill type insulation. Certainly making it during the fibre manufacturing process is the preferred way of doing it. On a typical multi-spinner line, a mixed single-glass/dual-glass thermal insulation product can be made by a proper sequencing of standard single-glass and dual-glass spinners.  
           [0017]    Thermal insulation material made as a mixture of single-glass straight and dual-glass curly fibers is expected to allow for substantially higher compression ratios during the product packaging stage, since a curly fiber component certainly can offer some extra springiness to the product, and this results in a better thickness recovery after compression release. It is likely that less binder will be needed to assure a required level of product integrity. Curly fibre has a better volume filling ability than a so called straight one, and naturally allows for some degree of fibre interlocking, mutual entanglement and self-cohesion. Slightly reduced thermal conductivity and therefore potential for some density reduction, is possible. Skin irritation and product dustiness, which are factors particularly important to product end-users or installers, should in principle be less pronounced as well.  
         SUMMARY OF THE INVENTION  
         [0018]    The object of the present invention is to provide a dual-glass spinner for manufacturing bi-component curly glass fibers at a production rate in principle comparable with the single-glass spinner operation. A mixed dual-glass/single-glass fibre insulation product can be made with a substantially improved allowable compression ratio, as determined by the minimum required thickness recovery after unpacking, much reduced binder content, and somewhat improved thermal insulation value.  
           [0019]    The inventors have produced a spinner for use in producing a bi-component fibreglass insulation product, including an interior slinger cup; said slinger cup being circumferentially secured in a fixed manner to a bottom of said spinner inwardly of said spinner periphery; said slinger cup having a bottom portion extending inwardly and being adapted to receive a first molten glass A which, through centrifugal movement, forces said glass A in an outward direction; said slinger cup further comprising a vertically extending circumferential wall and an upper horizontally extending flange adapted to receive a second stream of molten glass B with a different coefficient of thermal expansion than said first glass A; said glass B being forced outwardly through centrifugal movement; said spinner having a plurality of vertical baffles creating vertical chambers inwardly of a spinner peripheral wall; said slinger cup having a plurality of openings on an outwardly facing wall, such that glass A emerges into first of said vertical chambers and glass B emerges above said slinger cup horizontal flange into second alternative vertical chambers; said chambers being greater than 2 in number and lesser than 32 in number; said spinner further comprising a plurality of horizontal baffles disposed between said vertical chambers such that glass A and glass B enter separately from said vertical chambers between said baffles; said baffles creating alternate vertically disposed horizontal chambers; said spinner on its inner periphery wall having a plurality of apertures adapted to receive glass A from one horizontal chamber and glass B from an alternative upper or lower horizontal chamber; said apertures opening into either glass A or glass B channels; whereupon in operation each one of glass A channels and each one of glass B channels connects to a single common orifice through the spinner exterior peripheral wall; said spinner wall having a large number of orderly placed, single common orifices, thereby creating a bi-component primary glass fibre, which, after further attenuation by a combined action of a rotating spinner, external main burner and compressed air blower create curly irregularly shaped glass fibers, due to glass A and B having different coefficients of thermal expansion. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    The invention will be more clearly described in conjunction with the accompanying drawings wherein:  
         [0021]    [0021]FIG. 1A is a transverse cross section of a spinner used in the present invention;  
         [0022]    [0022]FIG. 1B which is an A-A cross-section of FIG. 1A is a top view of the spinner showing one half of the total circumference;  
         [0023]    [0023]FIG. 2 is an expanded view of one side of a transverse cross section of the spinner;  
         [0024]    [0024]FIG. 3 is a transverse cross section of approximately one half of the spinner with other components;  
         [0025]    [0025]FIG. 4 is similar to FIG. 2 with different components shown;  
         [0026]    [0026]FIGS. 5 and 6 are expanded views of the transverse cross section of the spinner&#39;s interior and exterior peripheral walls;  
         [0027]    [0027]FIG. 7 is a perspective view from the inside of the spinner peripheral wall showing a hole drilling pattern;  
         [0028]    [0028]FIG. 8A is section  1 - 1 ;  8 B is section  2 - 2 ; and  8 C is section  3 - 3  which show the channels through which the glass passes at various angles; and  
         [0029]    [0029]FIGS. 9A and 9C are respectively the view B and the cross-section A-A of FIG. 9B, showing the hole drilling patterns as seen from the outside and from the inside of the spinner; FIG. 9B is a repeated FIG. 8B, given here as a reference for easier visulization. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0030]    [0030]FIG. 1A is a transverse cross section of a spinner used to produce glass fibers through centrifugal force, heat, and air pressure. The spinner  1  is basically a round dish having a peripheral circumference with holes drilled therein. The spinner has an upper top side flange but otherwise has an open top which permits molten glass to enter into the spinner and be forced to the circumference. In FIG. 1A there is mounted within the spinner a slinger cup  2 . The slinger cup is fixedly mounted within the spinner. It has a peripheral wall or rim  3 , a slinger cup middle flange  4 , and a middle flange upturned member  4 A. The slinger cup also has a top flange  5 . The purpose of the slinger cup is to separate two molten glasses A and B. Molten glass B is directed into the slinger cup on top of the middle flange  4  whereas molten glass A falls inside the spinner  1  inwardly of the slinger cup middle flange upturned member  4 A.  
         [0031]    On examination of FIGS. 1A and 2, one views that a molten stream of glass B descends upon the slinger cup middle flange  4  while glass A falls to the bottom of slinger cup  2  and exits through glass A slots  6 . Glass B, on the other hand, exits through glass B slots  7 .  
         [0032]    As can be seen in FIG. 1B, the periphery of the spinner on the exterior side of the slinger cup  2  is divided into a number of chambers separated from one another by vertical baffles  9 . In a preferred embodiment, eight circumferential compartments are used, four for glass A and four for glass B. Hence, around the circumference of the slinger cup, glass B, directed through holes  7 , is directed to vertical chambers  8   b  and glass A is directed to alternate vertical chambers  8   a . From chambers  8   a  and  8   b , the molten glass is permitted to pass towards the periphery of spinner  1  by means of slots  12   a  for glass A, and  12   b  for glass B. Only those chambers marked as  8   a  permit the passage of glass A glass towards the periphery and only those chambers marked as  8   b , i.e. the alternate circumferential chambers, permit glass B to pass towards the periphery. Before proceeding further, it is noteworthy in FIG. 4 that the spinner bottom is marked as  11  and the spinner top as  10 . Slots  12   a  and  12   b , which are directed radially outwardly, are separated by ring-shaped internal horizontal flanges. Thus, glass A has access only to those slots  12   a  and glass B has access only to those slots  12   b . Within the peripheral wall, however, glass A slots pass towards circumferential cavities  14   a  and glass B passes through to circumferential cavities  14   b.    
         [0033]    Before proceeding with the essence of the invention, i.e. the peripheral hole formation, one must understand in FIG. 3 the basic components of the spinner mechanism. The spinner  1  turns at approximately 2400 r.p.m. In order to keep the molten glass at a sufficiently high temperature, there is an inner burner  20  and an inner burner deflector ring  21 . Spinner  1  is attached to a mounting hub  26  having a mounting cap  27 . Mounting hub  26  has a number of peripheral radially milled, and uniformly circumferentially spaced grooves or slots  22  to provide flow channels for allowing inner burner combustion products to communicate with the space right underneath spinner bottom. Spinner  1  has a slotted bottom radiation shield  25  to contain the heat upwards.  
         [0034]    Separating the slotted bottom radiation shield  25  from the spinner  1  is a slotted spacer ring  23 . Spinner  1  is also equipped with a number of spinner elevation adjustment spacers for adjusting the spinner in relation to the mounting hub  26 . Between the slotted bottom radiation shield  25  and the spinner bottom are a number of bottom radiation shield exit slots  28 . Mounting cap  27  mounts the spinner  1  to the mounting hub  26  by means of bolts.  
         [0035]    In FIG. 4, the spinner  1  has an inner peripheral wall  13  and an outer peripheral wall  16 . As previously mentioned, when glasses A and B enter the peripheral wall through slots  12   a  and  12   b , which are separated by horizontal flanges  15 . Within the circumferential wall are glass A circumferential rings  14   a  and glass B circumferential rings  14   b . Thus, as shown more clearly in FIG. 5, glass B and glass A are alternately permitted to enter through the circumferential wall bounded by inner peripheral wall  13  and outer peripheral wall  16 .  
         [0036]    [0036]FIG. 6 shows more closely the inner peripheral wall  13  and the outer peripheral wall  16  of the spinner. Slots  12   a  and  12   b  enter through the inner peripheral wall  13  and then become cylindrical cavities for glass A and glass B shown as  14   a  and  14   b , respectively. Separating these horizontally radially outwardly projecting cavities are horizontal flanges  15 .  
         [0037]    As glass A progresses outwardly through cylindrical cavities  14   a , it enters an inlet hole  17  on the inside of the outer peripheral spinner wall  16 . Similarly, as glass B progresses outwardly through cylindrical cavities  14   b , it also enters an inlet hole  17 . From common inlet holes  17 , in a preferred embodiment, a plurality of channels emerge, some lead outwards radially and some are angularly slanted and lead outwards.  
         [0038]    In a preferred embodiment there are four such channels generally labeled, as is shown in FIGS. 6, 7,  8  and  9  as  18   a ,  18   b ,  18   c  and  18   d . The outer side of peripheral wall  16  is equipped with a plurality of orderly placed holes  19   a  for outlet hole type A and  19   b  for outlet hole type B. Through this innovative configuration of slanted and radially outward channels, both glasses A and glasses B emerge from outer peripheral wall  16  through orifices  19   a  and  19   b , together side by side. Because of their different coefficients of thermal expansion, the two glasses shrink upon cooling to a different degree thus forming curly or irregularly shaped fibers which are then directed downwardly and collected on a foraminous belt conveyor equipped with suction.  
         [0039]    Drawings  8 A,  8 B,  8 C and  9 A,  9 B and  9 C show various configurations through different views, wherein glass A and glass B are lead through inlet holes  17  and the unique configuration of slanted and radially drilled channels which result in a uniform surface density, staggered and high hole count pattern of exit holes  19   a  and  19   b  on spinner surface, highly resembling or even matching a typical drilled hole configuration for the conventional single-glass spinners.  
         [0040]    In FIG. 8A, angle A is shown as the angle between two planes, i.e. the angle between radial channels and radially inclined channels.  
         [0041]    In FIG. 8B, angle B is the angle between flow channels in the radially inclined plane and a perpendicular to the spinner axis is between  15  and 60 degrees.  
         [0042]    In FIG. 8C, the angle C is the angle between the flow channels in the radially inclined plane and is between 25 and 75 degrees.  
         [0043]    The essence of the invention is a multiple, horizontal and alternate layering of glasses A and B along the height of inner surface of the spinner peripheral wall, combined with extruding them through the unique geometry of channels  18   a ,  18   b ,  18   c  and  18   d , drilled in spinner peripheral wall in such a way that the exit hole pattern for a dual-glass spinner is virtually the same as, or largely resembles the one used for a standard single-glass spinner of the same diameter. Although a preferred embodiment of the invention has been discussed, it is to be understood that the essence of the invention is to create a dual glass fibre or a bi-component fibre of a twisted or curly nature in high capacity output through the manipulation of vertical and horizontal flanges and a plurality of outgoing channels from glasses A and B which come together side by side through outlet hole type  19   a  and outlet hole type  19   b.