Method and apparatus for forming discrete microcavities in a filament wire

Abstract

A microcavity forming device is provided that includes a microcavity forming means of making microcavities in a surface of a heated filament wire. The microcavity forming means includes an array of teeth for engaging the surface along a length dimension of the filament wire. The device further includes a drawing means of drawing the filament wire along the length dimension. The drawing means draws the filament wire along the length dimension and the array of teeth engages the surface of the filament wire to form the microcavities.

1 . A microcavity forming device comprising: 
 microcavity forming means of making microcavities in a surface of a heated filament wire,    the microcavity forming means including an array of teeth for engaging the surface along a length dimension of the filament wire, and    drawing means of drawing the filament wire along the length dimension,    wherein the drawing means draws the filament wire along the length dimension and the array of teeth engages the surface of the filament wire to form the microcavities.    
     
     
         2 . The device of  claim 1  wherein the microcavity forming means includes: 
 a pair of rollers, each roller rotatably positioned on a longitudinal axis opposite the other roller,  
 at least one concave portion formed circumferentially on an external surface of each roller of the pair of rollers, the concave portion of one roller of the pair of rollers being aligned with the concave portion of the other roller of the pair of rollers to form a transverse slot, and  
 the array of teeth protruding from each of the concave portions,  
 wherein, as the pair of rollers rotate on respective longitudinal axes, a heated filament wire is drawn through the transverse slot, and the array of teeth engages the filament wire to form the microcavities in the filament wire.  
 
     
     
         3 . The device recited in  claim 2 , wherein the array of teeth includes at least two rows of teeth protruding circumferentially from the concave portion.  
     
     
         4 . The device of  claim 2 , wherein the rollers are made of silicon carbide.  
     
     
         5 . The device of  claim 1  wherein each tooth of the array of teeth has a height of 0.2-1.5 microns and a cross-section having a width of 0.2-1.5 microns.  
     
     
         6 . The device of  claim 1  wherein each tooth of the array of teeth has a height of 0.5-0.75 micron and a cross-section having a width of 0.5-0.75 micron.  
     
     
         7 . The device of  claim 1  wherein each tooth of the array of teeth has a height of 0.5 micron and a cross-section having a width of 0.5 micron.  
     
     
         8 . The device of  claim 1  wherein a spacing between each tooth of the array of teeth ranges from 1 to 2 times a width of the tooth.  
     
     
         9 . The device of  claim 1  wherein each microcavity formed in the filament wire includes a cross-sectional width of approximately 1.5 times a width of the tooth.  
     
     
         10 . The device of  claim 1  wherein each microcavity formed in the filament wire includes a depth of approximately 0.6 times a height of the tooth.  
     
     
         11 . The device recited in  claim 1 , wherein each tooth in the array is made of silicon carbide.  
     
     
         12 . The device of  claim 1  wherein the microcavity forming means includes: 
 a first pair of rollers, each roller of the first pair rotatably positioned on a respective longitudinal axis, each respective longitudinal axis being opposite the other longitudinal axis,  
 a second pair of rollers, each roller of the second pair rotatably positioned on a respective transverse axis, each respective transverse axis being opposite the other transverse axis, the second pair of rollers disposed downstream of the first pair of rollers,  
 a concave portion formed circumferentially on an external surface of each roller of the first and second pairs,  
 the concave portion of a roller of the first pair being aligned at an angle of substantially 90 degrees with respect to the concave portion of a roller of the second pair, the concave portions of each pair of rollers forming a cross sectional slot,  
 the array of teeth protruding from each of the concave portions,  
 wherein, as the first and second pairs of rollers rotate respectively, on the longitudinal axes and transverse axes, a heated filament wire is drawn through each of the slots, and the array of teeth engages the filament wire to form the microcavities in the filament wire.  
 
     
     
         13 . The device of  claim 12 , wherein the rollers are made of silicon carbide.  
     
     
         14 . The device of  claim 1  wherein the microcavity forming means includes: 
 a first pair of opposing rollers mounted for rotation along a first longitudinal axis and positioned to rotatably receive a heated filament wire moving in a transverse downstream direction,  
 a second pair of opposing rollers mounted for rotation along a second longitudinal axis and positioned downstream from the first pair of rollers to rotatably receive the moving heated filament wire, the second longitudinal axis being angularly displaced from the first longitudinal axis, and  
 each opposing roller including the array of teeth protruding circumferentially from an external surface of each roller,  
 wherein the pairs of rollers rotatably receive the moving filament wire and the array of teeth engages the filament wire to form the microcavities in the filament wire.  
 
     
     
         15 . The device of  claim 14 , wherein the rollers are made of silicon carbide.  
     
     
         16 . The device of  claim 14  wherein the microcavity forming means includes: 
 a third pair of opposing rollers mounted for rotation along a third longitudinal axis and positioned downstream from the second pair of rollers to rotatably receive the moving heated filament wire, the third longitudinal axis angularly displaced from the second longitudinal axis.  
 
     
     
         17 . The device of  claim 1  wherein the microcavity forming means includes: 
 a first endless track extending around a first pair of rollers, in which the first pair of rollers imparts a movement to the first endless track along a longitudinal dimension and around the first pair of rollers,  
 a second endless track extending around a second pair of rollers, in which the second pair of rollers imparts a movement to the second endless track along the longitudinal dimension and around the second pair of rollers,  
 the first and second endless tracks positioned to buttress the heated filament wires, and  
 the array of teeth protruding from the first and second endless tracks,  
 wherein the first and second endless tracks are adapted to move with the heated filament wire along the longitudinal dimension, and the array of teeth engage the moving filament wire to form the microcavities in the filament wire.  
 
     
     
         18 . The device of  claim 17  wherein the microcavity forming means further includes: 
 third and fourth endless tracks, each extending around third and fourth pairs of rollers, respectively, for imparting movements to the third and fourth endless tracks along the longitudinal dimension of the filament wire,  
 the third and fourth endless tracks positioned to buttress the filament wire, and positioned downstream from the first and second endless tracks, and perpendicularly to the first and second endless tracks, and  
 another array of teeth protruding respectively from the third and fourth endless tracks,  
 wherein the third and fourth endless tracks are adapted to move with the filament wire along the longitudinal dimension, and the other arrays of teeth engages the moving filament wire to form the microcavities in the filament wire.  
 
     
     
         19 . The device of  claim 17  wherein the drawing means includes 
 driving means of rotating the first and second pairs of rollers, and  
 the first and second endless tracks drawing the filament wire as the first and second pairs of rollers are driven by the driving means.  
 
     
     
         20 . The device of  claim 1  wherein the microcavity forming means includes: 
 a first pair of opposing presses, in which each opposing press includes a first contoured plate conforming to a portion of an outer surface of a filament wire, the filament wire having a longitudinal axis, and  
 the first pair of opposing presses adapted to move in a first transverse axis;  
 a second pair of opposing presses, positioned downstream along the longitudinal axis from the first pair of opposing presses, in which each opposing press includes a second contoured plate conforming to another portion of the outer surface of the filament wire, and  
 the second pair of opposing presses adapted to move in a second transverse axis, the second transverse axis angularly displaced from the first transverse axis; and  
 the array of teeth projecting outwardly from each first and second contoured plates;  
 wherein a heated filament wire is moved along the longitudinal axis and the first and second pair of opposing presses are moved, respectively, in the first and second transverse axes, and the array of teeth engage the heated filament wire to form the microcavities.  
 
     
     
         21 . The device of  claim 20  wherein the opposing presses are made of silicon carbide.  
     
     
         22 . The device of  claim 20  in which the drawing means includes start and stop controls for, respectively, starting and stopping the drawing of the filament wire along the length dimension, and further including 
 synchronization means of synchronizing the movement of the first and second pairs of opposing presses with the starting and stopping of the drawing of the filament wire,  
 wherein, in sequence, the drawing means draws the filament wire, stops the drawing of the filament wire, and the first and second pairs of opposing presses engage the filament wire.  
 
     
     
         23 . The device recited in  claim 20  wherein the microcavity forming means further includes: 
 a third pair of opposing presses positioned downstream along the longitudinal axis from the second pair of opposing presses, and each opposing press including a third contoured plate conforming to another portion of the outer surface of the filament wire;  
 the third pair of opposing presses adapted to move in a third transverse axis, and the third transverse axis angularly displaced from the second transverse axis; and  
 an array of teeth projecting outwardly from each third contoured plate;  
 wherein a heated filament is moved along the longitudinal axis and the third pair of opposing presses is moved in the third transverse axis, and the array of teeth engages the heated filament wire to form the microcavities.  
 
     
     
         24 . A method of making microcavities in a filament wire comprising the steps of: 
 (a) positioning each roller of a pair of rollers on a longitudinal axis opposite the other roller, in which each roller includes a concave portion formed circumferentially on an external surface, and further includes an array of teeth projecting from each respective concave portion;    (b) aligning the respective concave portions to form a transverse slot;    (c) rotating each roller on the respective longitudinal axis;    (d) drawing a heated filament wire through the transverse slot; and    (e) engaging the array of teeth with the heated filament wire to form the microcavities in the filament wire as each roller rotates in step (c).    
     
     
         25 . A method of making microcavities in a filament wire comprising the steps of: 
 (a) positioning each roller of a first pair of rollers on a respective longitudinal axis opposite each other, in which each roller includes a concave portion formed circumferentially on an external surface, and further includes an array of teeth projecting from each respective concave portion;    (b) positioning each roller of a second pair of rollers downstream from the first pair of rollers on a respective transverse axis opposite another roller of the second pair of rollers, in which each roller includes a concave portion formed circumferentially on an external surface, and further includes an array of teeth projecting from each respective concave portion;    (c) aligning the concave portion of a roller of the first pair substantially 90 degrees with respect to the concave portion of a roller of the second pair, the concave portions of each pair of rollers forming a cross sectional slot;    (d) drawing a heated filament wire through each slot; and    (e) engaging the array of teeth with the heated filament wire to form the microcavities in the filament as each roller rotates in response to drawing the heated filament wire through each slot.    
     
     
         26 . A method of making microcavities in a filament wire comprising the steps of: 
 (a) positioning a second pair of opposing rollers downstream from a first pair of opposing rollers in which each roller of the first and second pairs of rollers includes an array of teeth projecting from an external surface of each opposing roller;    (b) aligning the first and second pairs of opposing rollers along first and second longitudinal axes, respectively, in which the first and second longitudinal axes are angularly displaced from each other;    (c) rotating each roller of the pairs of opposing rollers;    (d) drawing a heated filament wire through the pairs of opposing rollers; and    (e) engaging the array of teeth with the heated filament wire to form the microcavities in the filament wire, as each roller rotates in step (c).    
     
     
         27 . The method recited in  claim 26 , further comprising the steps of: 
 (f) positioning a third pair of opposing rollers downstream from the second pair of opposing rollers, in which each roller of the third pair of opposing rollers includes an array of teeth projecting from an external surface of each opposing roller;    (g) aligning the third pair of opposing rollers along a third longitudinal axis, in which the third longitudinal axis is angularly displaced from the first and second longitudinal axes.    
     
     
         28 . A method of making microcavities in a filament wire comprising the steps of: 
 (a) positioning first and second endless tracks to buttress a plurality of heated filament wires between the first and second endless tracks in which each of the first and second endless tracks extends around, respectively, first and second pairs of rollers, and includes a plurality of teeth projecting from each surface of the first and second endless tracks;    (b) rotating the first and second pairs of rollers to impart movements to the first and second endless tracks along a longitudinal axis;    (c) drawing the heated filament wires between the first and second endless tracks; and    (d) engaging the plurality of teeth with the heated filament wires to form the microcavities in the filament wires, as the first and second endless tracks are moved.    
     
     
         29 . A method of making microcavities in a filament wire comprising the steps of: 
 (a) positioning a second pair of opposing presses downstream along a longitudinal axis from a first pair of opposing presses in which each opposing press includes a contoured plate having an array of teeth projecting therefrom;    (b) moving the first and second pairs of opposing presses in opposition along first and second transverse axes, respectively, the first transverse axis angularly displaced from the second transverse axis;    (c) drawing a heated filament wire along the longitudinal axis and between the contoured plates of the pairs of opposing presses; and    (d) engaging the arrays of teeth with the heated filament wire to form the microcavities in the heated filament wire.    
     
     
         30 . The method of  claim 29  further including the steps of: 
 (e) positioning a third pair of opposing presses along the longitudinal axis and downstream from the second pair of opposing presses in which each opposing press includes a contoured plate having an array of teeth projecting therefrom; and  
 (f) moving the third pair of opposing presses in opposition along a third transverse axis, the third transverse axis angularly displaced from the first and second transverse axes;  
 
     
     
         31 . A method of making a roller for forming microcavities in a heated filament wire, the method comprising the steps of: 
 (a) forming an external surface of a cylindrical structure with silicon carbide; and    (b) projecting circumferentially an array of teeth from the external surface, in which each tooth of the array is made from silicon carbide.    
     
     
         32 . The method of  claim 31  in which forming the external surface includes shaping the external surface to include at least one circumferential concave portion, and 
 projecting the array of teeth from the shaped circumferential concave portion.