Method and apparatus for making glass fibers utilizing an oscillating spinner

Abstract

Attempts have been made by the prior art to oscillate a veil of air entrained centrifugally spun fibers back and forth across a moving collecting surface to build a layer of fibers having uniform thickness and density. The present invention accomplishes this objective by oscillating a fiberizing rotor, preferably about an axis that runs through the bottom wall of the spinner.

What we claim is: 
     
       1. In a method of making a fibrous mat comprising feeding a molten material to a rotor, rotating the rotor at a high speed to form fibers, stripping the fibers from the exterior of the rotor to form a column of loose fibers, and moving said column back and forth across the width of a collection surface, the width of said collection surface being substantially greater than the width of said column of loose fibers; the improvement comprising: moving said column of fibers by moving the rotor such that the rotor's axis of rotation is moved such that said column of fibers is swept back and forth to form said fibrous mat across the width of said collection surface. 
     
     
       2. A method as defined in claim 1 wherein the rotor's axis is oscillated back and forth in a single plane. 
     
     
       3. A method as defined in claim 2 wherein said axis is moved by being pivoted about a line that is within six inches from the bottom wall of the rotor. 
     
     
       4. A method as defined in claim 3 wherein the pivot point lies within the bottom wall of the rotor. 
     
     
       5. A method as defined in claim 3 wherein the rotor has a peripheral wall containing a plurality of openings and the fibers are formed by molten material passing through the openings due to centrifugal force created by the spinning rotor. 
     
     
       6. A method as defined in claim 5 wherein the formed fibers are stripped from around the rotor by moving gases, the temperature of these gases being insufficient to promote attenuation of the fibers. 
     
     
       7. A method as defined in claim 6 wherein the collection surface is moving in a direction transverse to the plane in which the rotor's axis is being moved. 
     
     
       8. A method as defined in claim 7 wherein the pivot point for the rotor's axis lies on a surface of, or within, the bottom wall of the rotor. 
     
     
       9. A method as defined in claim 2 wherein the rate at which said axis is moved is changed during at least one portion of a cycle of oscillation. 
     
     
       10. A method as defined in claim 9 wherein the rate is increased near the extremities of the movement of the axis to compensate for any delay in stopping the movement of the axis in one direction and in starting the axis moving back in an opposite direction. 
     
     
       11. A method as defined in claim 8 wherein the rate at which said axis is moved is changed during at least one portion of a cycle of oscillation. 
     
     
       12. A method as defined in claim 11 wherein the rate is increased near an extremity of the movement of the axis to compensate for any delay in stopping the movement of the axis in one direction and in starting the axis moving back in an opposite direction. 
     
     
       13. A method as defined in claim 2 wherein the axis is moved along a curved path about a point spaced from said path. 
     
     
       14. A method as defined in claim 8 wherein said axis is oscillated at a rate of at least about 0.2 cycles per second. 
     
     
       15. A method as defined in claim 8 wherein said molten material is inorganic. 
     
     
       16. A method as defined in claim 15 wherein said molten material is a glass composition. 
     
     
       17. A method as defined in claim 3 wherein said molten material is a glass composition. 
     
     
       18. In an apparatus for forming fibers by centrifugal force comprising.Iadd.: .Iaddend.a rotor means for forming a column of the fibers, said rotor .Iadd.means .Iaddend.having a bottom wall, means for feeding molten material to said rotor .Iadd.means.Iaddend., means for rotating the rotor means about an axis of rotation, means for supporting said rotor .Iadd.means.Iaddend., and means for collecting said fibers in mat form, said collecting means being substantially wider than said column of fibers; the improvement comprising: means for moving said rotational axis while said rotor .Iadd.means .Iaddend.is rotating such that said axis pivots about a line located within about 6 inches from the bottom wall of said rotor .Iadd.means .Iaddend.and such that said column of fibers is swept back and forth across the width of said collection means. 
     
     
       19. An apparatus as defined in claim 18 wherein means for moving said rotational axis is capable of oscillating said axis back and forth such that the movement of said axis above said bottom wall defines a V-shaped configuration. 
     
     
       20. An apparatus as defined in claim 19, the improvement further comprising: means for monitoring the position of said axis, and   means cooperating with said monitoring means and said moving means for changing the direction of movement of said rotational axis.   
     
     
       21. An apparatus as defined in claim 20, the improvement further comprising: means cooperating with said, moving means for changing the rate of movement of said rotational axis.   
     
     
       22. An apparatus for forming a layer of centrifugally formed fibers comprising: a. fiberizing means comprising a rotor and means for rapidly rotating said rotor about a rotational axis,   b. means for feeding molten material to said rotor,   c. a horizontal support for supporting said fiberizing means, said horizontal support being rotatable about a horizontal axis, said horizontal axis being in a plane that also lies in a bottom wall of said rotor, and   d. oscillating means for causing said horizontal support to rotate and counter rotate in an oscillating manner whereby the rotational axis of said rotor pivots about a point lying within the bottom wall of said rotor.   
     
     
       23. An apparatus as defined in claim 22 wherein said horizontal support is a hollow tube, and a plurality of pipes pass through the hollow interior of said tube for providing services to said fiberizing means.