Abstract:
A method and apparatus for conditioning loose-fill insulation including an elongated tubular cylinder having a plurality of internal blades positioned in a helical configuration. Large nodules of glass fibrous material pass through the conditioning cylinder and are combed into smaller, more uniform sizes, thus allowing a more uniform additive application further downstream in the manufacturing process. The addition of a tangential airflow to the conditioning cylinder facilitates the combing process by adding a tangential force to move the nodules down the cylinder.

Description:
FIELD OF THE INVENTION 
     The invention relates to the production of mineral fiber material, and more particularly, to materials such as glass fibers. Specifically, the invention relates to making loose fibrous material of a type suitable for the manufacture of fiber glass products including loose-fill, blown-in type insulation. 
     BACKGROUND OF THE INVENTION 
     Loose-fill insulations are either produced as—or broken down into—shreds, granules, or nodules. These small particles form fluffy materials that conform to the spaces in which they are installed. Loose-fills are most commonly sold in bags and are blown into building cavities using special equipment. 
     Loose-fill insulations are well suited for places where it is difficult to install other types of insulation, for example, irregularly shaped areas, around obstructions (such as plumbing stacks), and in hard-to-reach places. They can be installed in either enclosed cavities such as walls or unenclosed spaces such as attics. Blown-in loose-fills are particularly useful for retrofit situations because, except for the holes that are sometimes drilled for installations, they are one of the few materials that can be installed without greatly disturbing existing finishes. 
     One common type of loose-fill, fiber glass loose-fill insulation is spun from molten glass into fibers. The glass is typically melted in high-temperature gas or electric furnaces and often includes about 20% to 30% of recycled glass content. 
     There are several performance characteristics to consider when selecting a loose-fill insulation material. Among the most important to consider are insulating capacity, weight, convective heat loss, settling and loss of insulating capacity. A material&#39;s resistance to heat flow is expressed as its R-value. The higher the R-value, the better the material insulates, and the lesser the thickness required to achieve a desired result. 
     Loose-fill insulations are produced by a variety of methods known in the art. For example, a common method of production involves supplying streams of molten glass to conventional rotary fiberizers to form veils of glass fibers. At this point, an additive, usually an anti-static organic agent, is applied to the glass fibers. These veils of glass fibers are typically collected onto conveyors, then pass though equipment, such as a flail which cuts and shreds them into fiber nodules. From that point, the nodules are pneumatically conveyed to other conditioning equipment where special additives such as dust reduction oil are applied, then through a nodulator for further conditioning and finally to packaging equipment. 
     The processing steps of cutting and shredding loose-fill fiber glass insulation are often very rough processing and not efficient. Higher performance cutting and shredding of loose-fill insulation is cost prohibitive, requiring the manufacturer to purchase and maintain separate and expensive machinery to produce the desired form of the insulation. Another problem with conventional processing techniques is that they tend to produce a dispersed glass fiber nodule size. That is, the nodule size generally is not uniform. A more uniform nodule size would permit a better additive distribution, which would in turn optimize the products performance as an insulation. 
     Improved methods of and apparatus for forming loose-fill fiber glass insulation materials with less dispersed glass fiber nodule size distribution are therefore desirable. 
     SUMMARY OF THE INVENTION 
     The present invention provides for a system for conditioning glass fiber nodules, the system including a conditioning duct having an elongated cylindrical tube with a plurality of blades disposed in a helical configuration around the cylindrical tube. The blades extend radially inward from an inside surface of the cylindrical tube and serve to break apart the veils of glass fibers to provide a more uniform nodule size distribution than otherwise obtained using conventional techniques. The conditioning duct is in preference installed between the flail and the nodulator in order to offer an efficient fiber cutting and shredding, although it could be installed in other areas of pneumatic transport duct. 
     An air inlet may also be incorporated into the conditioning duct, whereby pressurized air enters the inlet and provides a tangential airflow through the duct. The air flowing into the duct via the inlet induces a rotation in the glass fiber nodules disposed in the duct and serves to push the nodules through the blades. 
     Another aspect of the system lies in a method for processing loose-fill insulation is provided and includes the step of: passing loose-fill insulation material through an elongated duct having a plurality of internally disposed blades in a helical configuration. Tangential airflow may also be provided to the duct to impart a rotational effect on the insulation materials for improved processing through the duct. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other aspects, advantages and novel features of the invention will become more apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings wherein: 
     FIG. 1 is a front elevational diagram of an exemplary embodiment of the conditioning duct, illustrating the air inlets and the helical positioning of blades within the duct; 
     FIG. 2 is a front elevational view of an exemplary individual blade; and 
     FIG. 3 is a diagram showing the blade orientation in the conditioning duct, as viewed in cross-section. 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1 and 2 illustrate a preferred embodiment of the loose-fill insulation conditioning system  10 . The system  10  includes a conditioning duct  12  having a plurality of radially disposed processing blades  14 . The blades  14  are attached to the inside of the duct  12  in a helical configuration and “comb” insulation materials such as, for example, fiber glass nodules that are processed through the conditioning duct  12 . Air conduits  16  may be provided at an upstream end  18  of the duct  12  to provide tangential airflow to the interior of the duct  12  to facilitate processing of loose-fill insulation. 
     Referring still to FIGS. 1 and 2, conditioning duct  10 , according to a preferred embodiment, is an elongated, cylindrical, tubular, steel member having a diameter  20  of between about 12 inches and 24, inches more preferably between 14 inches and 22 inches and most preferably between 16 inches and 20 inches. The duct  10  has a length  15  of between about twelve feet (12 ft) and twenty feet (20 ft) and is preferably sixteen feet (16 ft) long. The duct wall  22  includes a plurality of through holes  13  for radially mounting processing blades  14 . The mounting holes  13  are positioned on a line forming a helix, along the length of the duct  10 , and the line preferably being oriented at an angular inclination alpha (a) of about forty-five (45) degrees from a plane perpendicular from the longitudinal axis of the duct  12 . In other words, the helix has a pitch of about 45 degrees. Consecutive mounting holes  13 , and corresponding blades  14 , have a longitudinal spacing  34  of between about 1 inch and 3 inches, and are preferably spaced 2 inches apart. The circumferential spacing  36  of consecutive blades is between about 0.5 inch and 4 inches, more preferably between 1 inch and 3 inches, and most preferably between 1.5 inches and 2.5 inches. Variations in pitch ranging from between about thirty (30) degrees and about seventy (70), degrees and more preferably between 35 and 50 degrees, are contemplated within the scope of the invention, and may be desirable depending on a variety of factors including the size, type and spacing of blades  14 , airflow and pressure in the duct  12 , and the material processed. 
     Tangential air flow may be applied through a plurality of air conduits  16  located near the upstream end of conditioning duct  12 , to facilitate fiber nodule movement and processing through the duct  12 . In the embodiment shown in FIG. 1, tangential airflow is applied through three air conduits  16 , each having a one inch (1″) diameter. 
     FIG. 2 shows an exemplary processing blade  14 , having an attachment means, which may be a threaded rod  24  having a nut  26  threaded thereon. The threaded rod  24  has a diameter  28  that is slighter smaller than the diameter of mounting holes  13 , thereby permitting insertion of the threaded rods  24  in corresponding mounting holes  13 . Once inserted, a second nut (not shown) may be applied to each threaded rod to detachably secure each processing blade  14  in position. When blade  14  is fastened to the duct wall  12 , the blade  14  is oriented perpendicular to the longitudinal axis of the duct  12 . The portion of the blade that is exposed to and “combs” the insulation, is referred to herein as the combing portion  30 . The combing portion is  30 , in the embodiment shown, is a straight blade having a length  32  which is between 0.5 inches and 4 inches, more preferably between 1 inch and 3 inches and most preferably 1.5 and 2.5 inches, and a generally rectangular cross-section, although other configurations are feasible and contemplated within the scope of the invention, including, but not limited to, an “ice-pick” like blade configuration. It will also be apparent to those skilled in the art that other conventional fasteners may alternatively be employed. 
     FIG. 3 shows the blade orientation in the conditioning duct  12 , as viewed in cross-section. Multiple blades  14  can be seen positioned within the conditioning duct  12 . The blades  14  extend generally radially inward from the duct wall  22 , but are eccentrically advanced from a radial direction in order to facilitate processing of the losse-fill insulation and movement of the insulation through the conditioning duct  12  in concert with the tangential airflow. 
     In operation, glass fiber nodules are introduced at the upstream end  18  of duct  12 . The longitudinal axis of the duct  12  has a vertical orientation. Thus, loose-fill insulation may be in-part, gravity fed into the upstream end  18  of the duct  12 . A positive pressure of about 4 psi is maintained in the duct  12  during processing of the loose-fill insulation. In addition, tangential airflow may be introduced near the upper (inlet) end  18  of the duct to impart a rotational effect on the loose-fill insulation. Advantageously, the rotational air and the helical blade configuration together impart a cyclone-like rotation of the glass fiber nodules, which “combs” the large glass fiber nodules into smaller more uniform ones, as the materials pass through the conditioning duct  12  and blades  14 . Small uniform nodules facilitate a more uniform additive distribution during subsequent processing. 
     The following results (Table 1) were achieved employing a plurality of helically configured blades each having a two inch (2″) blade length  32  and a one-eighth inch (⅛″) blade width  35 . Consecutive blades were circumferentially spaced three inches (3″) apart and longitudinally spaced three inches (3″) apart. The blades were mounted in a conveying duct  12 , having an 18″ diameter along a 16 ft. length. 
     
       
         
               
               
               
             
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Direction of 
                 R-Values 
               
               
                 ICD Trial # 
                 blow hose 
                 Obtained 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 STD 
                 MD* 
                 28.23 
               
               
                 STD 
                 MD 
                 26.90 
               
               
                 STD 
                 Reverse MD 
                 30.75 
               
               
                 STD 
                 Reverse MD 
                 29.09 
               
               
                   
                 Average 
                 28.74 
               
               
                 ICD 
                 MD 
                 28.9 
               
               
                 ICD 
                 MD 
                 28.68 
               
               
                 ICD 
                 Reverse MD 
                 30.26 
               
               
                 ICD 
                 Reverse MD 
                 29.92 
               
               
                   
                 Average 
                 29.44 
               
               
                   
               
               
                 *MD = Mandrel Direction  
               
             
          
         
       
     
     The foregoing test results, performed after one month of storage of the conditioned loose-fill insulation, show an improvement in R-value for loose-fill insulation processed in accordance with the system and methods described herein (“ICD”). The thermal resistance was tested and obtained in accordance with ASTM C518 at a mean temperature of 75° F. 
     The following results (Table 2) were achieved employing a plurality of helically configured blades each having a two inch (2″) blade length  32  and a one-eighth inch (⅛″) blade width  35 . Consecutive blades were circumferentially spaced two inches (2″) apart and longitudinally spaced two inches (2″) apart. 
     
       
         
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Trial 
                 Individual 
                 Average 
               
               
                 Number 
                 R-value 
                 R-value of two tests 
               
               
                   
               
             
             
               
                 STD-1 and 
                 31.03 
                 31.36 
               
               
                 STD-7 
                 31.68 
               
               
                   
                 31.62 
                 31.65 
               
               
                   
                 31.67 
               
               
                 STD Average 
                   
                 31.50 
               
               
                 ICD-2 
                 31.30 
                 31.35 
               
               
                   
                 31.40 
                 (−0.15) 
               
               
                 ICD-3 
                 31.57 
                 31.45 
               
               
                   
                 31.32 
                 (−0.05) 
               
               
                 ICD-4 
                 32.27 
                 31.96 
               
               
                   
                 31.65 
                 (+0.45) 
               
               
                 ICD-5 
                 31.16 
                 31.7  
               
               
                   
                 32.33 
                 (+0.20) 
               
               
                 ICD-6 
                 32.08 
                 31.98 
               
               
                   
                 31.87 
                 (+0.45) 
               
               
                   
               
               
                 Trial Conditions for Table 2:  
               
               
                 No. 1 &amp; 7: standard production conditions  
               
               
                 No. 2: Blades 2″ length and spaced 2″ longitudinally and 2″ circumferentially  
               
               
                 No. 3: same as No. 2 with additional 4 PSI air flow through 3 pipes of 1″ diameter  
               
               
                 No. 4: Blades 2″ length and spaced 1″ longitudinally and 2″ circumferentially  
               
               
                 No. 5: same as No. 4 and with 4 PSI tangential air flow through 3 pipes of 1″ diameter.  
               
               
                 No. 6: Blades 2″ length and spaced 3″ longitudinally and 3″ circumferentially  
               
             
          
         
       
     
     The foregoing test results show an improvement in R-value for loose-fill insulation processed in accordance with the system and methods described herein (“ICD”), as compared to loose-fill insulation processed using conventional techniques (“STD”). The thermal resistance was tested and obtained in accordance with ASTM C518 at a mean temperature of 75° F. 
     The loose-fill conditioning system is an efficient way of obtaining an improved nodule size distribution having little cost to install and virtually no cost to maintain, which in turn permits a better distribution of additives. The system ultimately results in loose-fill insulations having improved insulating properties vis-a-vis loose-fill insulations formed using conventional techniques. 
     Although the invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments of the invention which may be made by those skilled in the art without departing from the scope and range of equivalents of the invention.