Electric Induction Heating of a Rail Head with Non-Uniform Longitudinal Temperature Distribution

Abstract

A method is provided for making the longitudinal temperature distribution of the bulbous end of a longitudinally oriented workpiece, such as a rail's head, generally uniform when the head has a non-uniform longitudinal temperature distribution. A combination of crown and skirt electric inductors is used to achieve the generally uniform temperature distribution by modulating the magnetic field intensity produced by current flow through one or more of the combination of crown and skirt inductors as required for the non-uniformly heated regions of the rail's head.

1 . A method of electric induction heating of a bulbous end of a longitudinally oriented workpiece, wherein at least the bulbous end is electrically conductive, the method comprising:
 alternately passing the longitudinally oriented workpiece through an at least one crown inductor and an at least one skirt inductor with the bulbous end oriented beneath the at least one crown inductor and between the at least one skirt inductor, the at least one crown inductor comprising a central longitudinal section under which the top of the bulbous end passes through, and a right flank longitudinal section and left flank longitudinal section within which the flanks of the bulbous end passes though, the at least one skirt inductor comprising opposing right and left side skirt inductor sections which the sides of the bulbous end passes through; and   applying alternating current power to the at least one crown inductor and the at least one skirt inductor to generate a magnetic field around the at least one crown inductor and the at least one skirt inductor so that magnetic flux couples with the electrically conductive bulbous end to induce heating by eddy current.   
     
     
         2 . The method of  claim 1  further comprising moving at least one of the at least one crown inductor or the at least one skirt inductor while alternately passing the longitudinally oriented workpiece through the at least one crown inductor and the at least one skirt inductor. 
     
     
         3 . The method of  claim 1  wherein the right flank longitudinal section and the left flank longitudinal section of at least one of the at least one crown inductor each having a length shorter than the length of the central longitudinal section of the at least one of the at least one crown inductor and are disposed on opposing sides of the central longitudinal section. 
     
     
         4 . The method of  claim 3  wherein the central longitudinal section of the at least one of the at least one crown inductor has an opposing first and second central section ends, the right flank longitudinal section has an opposing first and second right flank section ends, the left flank longitudinal section has an opposing first and second left flank section ends; the first right flank section end being connected to the first central section end by a first connecting segment, and the first left flank section end being connected to the second central section end by a second connecting segment, with the applied alternating current power connected between the second right flank section end and the second left flank second end. 
     
     
         5 . The method of  claim 3  wherein the central longitudinal section of the at least one of the at least one crown inductor comprises a first partial central section having an opposing first and second, first partial central section ends, and a second partial central section having an opposing first and second, second partial central section ends, the right flank longitudinal section having an opposing first and second right flank section ends, the left flank longitudinal section having an opposing first and second left flank section ends, the first end of the first partial central longitudinal section being connected to the first end of the right flank section, the first end of the second partial central section being connected to the first end of the left flank section, the second ends of the first and second partial central sections being located near each other, with the applied alternating current power connected between the second ends of the right flank and second partial central sections, and the second ends of the left flank and first partial central sections so that instantaneous current flow is either through the right flank section and then through the first partial central section, and through the second partial central section and then through the left flank section, or through the first partial central section and then through the right flank section, and through the left flank section and then through the second partial central section. 
     
     
         6 . The method of  claim 3  wherein the right side skirt inductor section of at least one of the at least one skirt inductor comprises a first partial right side skirt inductor section and a second partial right side skirt inductor section, and the left side skirt inductor section of the at least one of the at least one skirt inductor comprises a first partial left side skirt inductor section and a second partial left side skirt inductor section; the first partial right side skirt inductor section having an opposing first and second, first partial right side skirt inductor section ends, the second partial right side skirt inductor section having an opposing first and second, second partial right side skirt inductor section ends, the first partial left side skirt inductor section having a first and second, first partial left side skirt inductor section ends, the second partial left side skirt inductor section having a first and second, second partial left side skirt inductor section ends, the first ends of the first partial right and left side skirt inductor section ends connected together by a first connecting segment, the first ends of the second partial right and left side skirt inductor section ends connected together by a second connecting segment, the second ends of the first and second partial right side skirt inductor sections located near each other, and the seconds ends of the first and second partial left side skirt inductor sections located near each other, a crossover section connecting the second ends of the second partial right side skirt inductor section and the first partial left side skirt inductor section, with the applied alternating current power connected between the second end of the first partial right side skirt inductor section and the second end of the second partial left side skirt inductor section. 
     
     
         7 . The method of  claim 3  wherein the right side skirt inductor section of at least one of the at least one skirt inductor having an opposing first and second right side skirt inductor ends, the left side skirt inductor section of the at least one of the at least one skirt inductor having an opposing first and second left side skirt inductor ends, the first ends of the right and left side skirt inductor sections located near each other, the first ends of the right and left side skirt inductor sections connected together by a crossover section, with the applied alternating current power connected between the second ends of the right and left side skirt inductor sections. 
     
     
         8 . The method of  claim 1  where in the cross sectional temperature profile of the bulbous section is non-uniform along the longitudinal length of the longitudinally oriented workpiece prior to alternately passing the longitudinally oriented workpiece through the at least one crown inductor and the at least one skirt inductor, further comprising adjusting the applied alternating current power to the at least one crown inductor or the at least one skirt inductor as the longitudinally oriented workpiece passes through the at least one crown inductor and the at least one skirt inductor so that the cross sectional temperature profile of the bulbous section is substantially uniform along the longitudinal length of the longitudinally oriented workpiece upon exiting the at least one crown inductor and the at least one skirt inductor. 
     
     
         9 . The method of  claim 8  further comprising:
 measuring the temperature of at least one point on the longitudinally oriented workpiece before alternately passing the longitudinally oriented workpiece through the at least one crown inductor and the at least one skirt inductor, or while the workpiece is passing through the at least one crown inductor and the at least one skirt inductor; and 
 adjusting the intensity of the magnetic field by adjusting the applied power to the at least one crown inductor or skirt inductor, responsive to the measured temperature of the at least one point. 
 
     
     
         10 . A method of electric induction heating of a bulbous end of a longitudinally oriented workpiece, wherein at least the bulbous end is electrically conductive, the method comprising:
 alternately moving an at least one crown inductor over the top of the bulbous end of the longitudinally oriented workpiece for at least a partial length of the longitudinally oriented workpiece, and an at least one skirt inductor around the side of the bulbous end of the longitudinally oriented workpiece for at least a partial length of the workpiece, the at least one crown inductor comprising a central longitudinal section positioned over the top of the bulbous end as the at least one crown inductor moves, and a right and left flank longitudinal sections between which the flanks of the bulbous end are positioned as the at least one crown inductor moves, the at least one skirt inductor comprising opposing right and left side skirt inductor sections between which the sides of the bulbous end are positioned as the at least one skirt inductor moves; and   applying alternating current power to the at least one crown inductor and the at least one skirt inductor to generate a magnetic field around the at least one crown and skirt inductors so that magnetic flux couples with the electrically conductive bulbous end to induce heating by eddy current.   
     
     
         11 . The method of  claim 10  further comprising moving the longitudinally oriented workpiece through at least one of the at least one crown inductor or the at least one skirt inductor. 
     
     
         12 . A method of electric induction heating of a rail head of a rail, wherein at least the rail head is electrically conductive, the method comprising:
 alternatively moving the rail alternately through an at least one crown inductor and an at least one skirt inductor or moving the at least one crown inductor and the at least one skirt inductor around the rail, or in combination, moving the rail alternately through the at least one crown inductor and the at least one skirt inductor and moving the at least one crown inductor and the at least one skirt inductor around the rail, so that the rail head is oriented beneath the at least one crown inductor and between the at least one skirt inductor, the at least one crown inductor comprising a central longitudinal section under which the crown of the rail head passes through, and a right flank longitudinal section and left flank longitudinal section within which the flange corner surfaces of the rail head passes though, the at least one skirt inductor comprising opposing right and left side skirt inductor sections which the sides of the rail head passes through; and   applying alternating current power to the at least one crown inductor and the at least one skirt inductor to generate a magnetic field around the at least one crown inductor and the at least one skirt inductor so that magnetic flux couples with the electrically conductive rail head to induce heating by eddy current.   
     
     
         13 . The method of  claim 12  wherein the right flank longitudinal section; and a left flank longitudinal section of at least one of the at least one crown inductor each had a length shorter than the length of the central longitudinal section of the at least one of the at least one crown inductor and are disposed on opposing sides of the central longitudinal section. 
     
     
         14 . The method of  claim 13  wherein the central longitudinal section of the at least one of the at least one crown inductor has an opposing first and second central section ends, the right flank longitudinal section has an opposing first and second right flank section ends, the left flank longitudinal section has an opposing first and second left flank section ends; the first right flank section end being connected to the first central section end by a first connecting segment, and the first left flank section end being connected to the second central section end by a second connecting segment, with the applied alternating current power connected between the second right flank section end and the second left flank second end. 
     
     
         15 . The method of  claim 13  wherein the central longitudinal section of the at least one of the at least one crown inductor comprises a first partial central section having an opposing first and second, first partial central section ends, and a second partial central section having an opposing first and second, second partial central section ends, the right flank longitudinal section having an opposing first and second right flank section ends, the left flank longitudinal section having an opposing first and second left flank section ends, the first end of the first partial central longitudinal section being connected to the first end of the right flank section, the first end of the second partial central section being connected to the first end of the left flank section, the second ends of the first and second partial central sections being located near each other, with the applied alternating current power connected between the second ends of the right flank and second partial central sections, and the second ends of the left flank and first partial central sections so that instantaneous current flow is either through the right flank section and then through the first partial central section, and through the second partial central section and then through the left flank section, or through the first partial central section and then through the right flank section, and through the left flank section and then through the second partial central section. 
     
     
         16 . The method of  claim 13  wherein the right side skirt inductor section of at least one of the at least one skirt inductor comprises a first partial right side skirt inductor section and a second partial right side skirt inductor section, and the left side skirt inductor section of the at least one of the at least one skirt inductor comprises a first partial left side skirt inductor section and a second partial left side skirt inductor section; the first partial right side skirt inductor section having an opposing first and second, first partial right side skirt inductor section ends, the second partial right side skirt inductor section having an opposing first and second, second partial right side skirt inductor section ends, the first partial left side skirt inductor section having a first and second, first partial left side skirt inductor section ends, the second partial left side skirt inductor section having a first and second, second partial left side skirt inductor section ends, the first ends of the first partial right and left side skirt inductor section ends connected together by a first connecting segment, the first ends of the second partial right and left side skirt inductor section ends connected together by a second connecting segment, the second ends of the first and second partial right side skirt inductor sections located near each other, and the seconds ends of the first and second partial left side skirt inductor sections located near each other, a crossover section connecting the second ends of the second partial right side skirt inductor section and the first partial left side skirt inductor section, with the applied alternating current power connected between the second end of the first partial right side skirt inductor section and the second end of the second partial left side skirt inductor section. 
     
     
         17 . The method of  claim 13  wherein the right side skirt inductor section of at least one of the at least one skirt inductor having an opposing first and second right side skirt inductor ends, the left side skirt inductor section of the at least one of the at least one skirt inductor having an opposing first and second left side skirt inductor ends, the first ends of the right and left side skirt inductor sections located near each other, the first ends of the right and left side skirt inductor sections connected together by a crossover section, with the applied alternating current power connected between the second ends of the right and left side skirt inductor sections. 
     
     
         18 . The method of  claim 12  where in the cross sectional temperature profile of the rail head is non-uniform along the longitudinal length of the rail prior to alternatively moving the rail alternately through the at least one crown inductor and the at least one skirt inductor or moving the at least one crown inductor and the at least one skirt inductor around the rail, or in combination, moving the rail alternately through the at least one crown inductor and the at least one skirt inductor and moving the at least one crown inductor and the at least one skirt inductor around the rail, further comprising adjusting the applied alternating current power to the at least one crown inductor or the at least one skirt inductor as the rail passes through the at least one crown inductor and the at least one skirt inductor so that the cross sectional temperature profile of the rail head is substantially uniform along the rail upon exiting the at least one crown inductor and the at least one skirt inductor. 
     
     
         19 . The method of  claim 18  further comprising:
 measuring the temperature of at least one point on the rail before alternatively moving the rail alternately through the at least one crown inductor and the at least one skirt inductor or moving the at least one crown inductor and the at least one skirt inductor around the rail, or in combination, moving the rail alternately through the at least one crown inductor and the at least one skirt inductor and moving the at least one crown inductor and the at least one skirt inductor around the rail, or while alternatively moving the rail alternately through an at least one crown inductor and an at least one skirt inductor or moving the at least one crown inductor and the at least one skirt inductor around the rail, or in combination, moving the rail alternately through the at least one crown inductor and the at least one skirt inductor and moving the at least one crown inductor and the at least one skirt inductor around the rail; and 
 adjusting the intensity of the magnetic field by adjusting the applied alternating current power to the at least one crown inductor or skirt inductor, responsive to the measured temperature of the at least one point.