Transverse Flux Electric Inductors

Abstract

An apparatus and process are provided for inductively heating a workpiece to a desired cross sectional temperature. At least one pair of coils form a transverse flux inductor. The workpiece is located between the pair of opposing coils, which are oriented across the cross section of the workpiece. Each coil comprises a plurality of coil sections. The distance between one or more opposing coil sections is adapted to achieve the desired cross sectional induction heating temperature profile in the workpiece. Alternatively the distance between all opposing coil sections are equidistant from each other, and one or more flux concentrators, moveable at least in a direction perpendicular to the surface of the workpiece, can be used to achieve the desired cross sectional induction heating temperature profile in the workpiece.

1 . An inductor for electric induction heating of an electrically conductive workpiece, the inductor comprising at least one pair of coils formed from a first and second coil, the electrically conductive workpiece placed between the pair of coils, the pair of coils oriented across the cross section of the workpiece, each of the first and second coils comprising a plurality of interconnected coil sections, at least one ac power supply suitably connected to the first and second coils of the inductor to supply ac power to the inductor,
 the improvement comprising,   at least two opposing coil sections of each of the first and second coils spaced apart at different distances to inductively heat the workpiece to a cross sectional temperature profile.   
   
   
       2 . The inductor of  claim 1  wherein the plurality of interconnected coil sections of each of the first and second coils comprises a pair of central sections generally centered over the center of the cross section of the workpiece; a transition section exclusively connected at its first end to each end of each of the pair of central sections; a shoulder section exclusively connected at its first end to the second end of each one of the transition sections; and at least one end section exclusively connected to the second ends of a pair of shoulder sections at each cross sectional edge of the workpiece. 
   
   
       3 . The inductor of  claim 2  wherein the distance between opposing central sections is greater than the distance between opposing shoulder sections. 
   
   
       4 . The inductor of  claim 3  wherein at least one end section is oriented away from the workpiece. 
   
   
       5 . The inductor of  claim 2  further comprising a second transition section exclusively connected between each of the shoulder and end sections. 
   
   
       6 . The inductor of  claim 1  further comprising at least one flux concentrator positioned at least partially around at least one of the coil sections. 
   
   
       7 . The inductor of  claim 1  further comprising at least one electromagnetic edge shield positioned at least partially around one edge of the workpiece. 
   
   
       8 . An inductor for electric induction heating of an electrically conductive workpiece, the inductor comprising:
 at least one pair of coils formed from a first and second coil, the electrically conductive workpiece placed between the pair of coils, the pair of coils oriented across the cross section of the workpiece, each of the first and second coils comprising a plurality of flexibly interconnected coil sections, at least two opposing coil sections of each of the first and second coils spaced apart at different distances from the workpiece; and   at least one ac power supply suitably connected to the first and second coils of the inductor to supply ac power to the inductor to inductively heat the workpiece to a cross sectional temperature profile.   
   
   
       9 . The inductor of  claim 8  wherein the first and second coils comprise a flexible composition. 
   
   
       10 . The inductor of  claim 8  wherein at least one adjacent coil sections are connected by an electrically conductive hinge. 
   
   
       11 . The inductor of  claim 8  further comprising an operator attached to at least one section of each of the first and second coils to move the at least one section of each of the first and second coils towards or away from the surface of the workpiece or to change the overall cross sectional width of the first and second coils. 
   
   
       12 . The inductor of  claim 8  further comprising at least one flux concentrator positioned at least partially around at least one of the coil sections. 
   
   
       13 . The inductor of  claim 12  further comprising an operator attached to the at least one flux concentrator to move the at least one flux concentrator relative to the at least one of the coil sections. 
   
   
       14 . The inductor of  claim 8  further comprising at least one electromagnetic edge shield positioned at least partially around one edge of the workpiece. 
   
   
       15 . The inductor of  claim 14  further comprising an operator attached to the at least one electromagnetic edge shield to move the at least one flux concentrator relative to the at least one of the coil sections. 
   
   
       16 . A method of inductively heating an electrically conductive workpiece comprising the steps of:
 forming an inductor from at least one pair of opposing first and second coils, each of the first and second coils comprising a plurality of interconnected sections;   orienting the electrically conductive workpiece between the at least one pair of opposing first and second coils with the cross section of the workpiece substantially aligned with the overall length of the at least one pair of opposing first and second coils;   spacing apart at different distances at least two pairs of opposing sections of the at least one pair of opposing first and second coils; and   supplying ac power supply to the at least one pair of first and second coils to inductively heat the workpiece to a cross sectional induction heating profile.   
   
   
       17 . The method of  claim 16  further comprising the steps of sensing the cross sectional temperatures of the inductively heated workpiece and adjusting the spaced apart distances of one or more opposing sections of the at least one pair of opposing first and second coils. 
   
   
       18 . The method of  claim 17  further comprising the steps of correlating the sensed cross sectional temperatures with one or more parameters of the workpiece; storing the correlated sensed cross sectional temperatures as a stored workpiece; comparing one or more parameters of a second workpiece prior to placing the workpiece between the at least one pair of first and second coils with the one or more parameters of the stored workpiece and adjusting the cross sectional induction heating profile for the second workpiece to the cross sectional induction heating profile of the stored workpiece when the one or more parameters of the stored workpiece and the second workpiece are equal. 
   
   
       19 . The method of  claim 16  further comprising the step of changing the spaced apart distances between at least one of opposing sections of the at least one pair of opposing first and second coils to change the overall width of the first and second coils. 
   
   
       20 . The method of  claim 16  further comprising the step of locating at least one flux concentrator at least partially around at least one of the coil sections. 
   
   
       21 . The method of  claim 16  further comprising the step of locating at least one electromagnetic edge shield at least partially around at one edge of the workpiece.