System and method for reducing current exiting a roll through its bearings

Abstract

A system includes a roll formed from a conductive material, where the roll is configured to rotate about an axis. The system also includes an induction heating workcoil configured to generate currents within the roll. The induction heating workcoil is unbalanced and is oriented so that minimal currents flow in a direction substantially parallel to the axis of the roll. The induction heating workcoil could include one or more substantially U-shaped or C-shaped cores and at least one coil each wound around at least one of the one or more cores. Also, the roll may further include a shaft and bearings, and the induction heating workcoil can be positioned so that the currents do not flow substantially through the bearings.

1 . A system comprising:
 a roll comprising a conductive material, the roll configured to rotate about an axis; and   an induction heating workcoil configured to generate currents within the roll, wherein the induction heating workcoil is unbalanced and is oriented so that minimal currents flow in a direction substantially parallel to the axis of the roll.   
     
     
         2 . The system of  claim 1 , wherein the induction heating workcoil comprises:
 one or more substantially U-shaped or C-shaped cores; and   at least one coil, each coil wound around at least one of the one or more cores.   
     
     
         3 . The system of  claim 1 , wherein:
 the roll further comprises a shaft and bearings; and   the induction heating workcoil is oriented so that the currents do not flow substantially through the bearings.   
     
     
         4 . The system of  claim 1 , wherein the roll comprises one of a set of counter-rotating rolls, the counter-rotating rolls configured to compress a web of material. 
     
     
         5 . The system of  claim 4 , wherein:
 an induction heating actuator comprises the induction heating workcoil and a power source coupled to at least one coil of the induction heating workcoil; and   the system further comprises a controller configured to control the power source to control an amount of compression provided by at least a portion of the counter-rotating rolls.   
     
     
         6 . The system of  claim 1 , wherein multiple induction heating workcoils are located adjacent to each other in a row proximate to the roll. 
     
     
         7 . The system of  claim 6 , wherein multiple rows of induction heating workcoils are located adjacent to each other proximate to the roll. 
     
     
         8 . A system comprising:
 a roll comprising a conductive material, the roll configured to rotate about an axis; and   an induction heating workcoil configured to generate a magnetic flux for producing currents within the roll, wherein the induction heating workcoil is unbalanced and is oriented so that a path of the magnetic flux through the roll is substantially parallel to the axis of the roll.   
     
     
         9 . The system of  claim 8 , wherein the currents within the roll do not flow substantially parallel to the axis of the roll. 
     
     
         10 . The system of  claim 8 , wherein the induction heating workcoil comprises:
 one or more substantially U-shaped or C-shaped cores; and   at least one coil, each coil wound around at least one of the one or more cores.   
     
     
         11 . The system of  claim 8 , wherein:
 the roll further comprises a shaft and bearings; and   the induction heating workcoil is oriented so that the currents do not flow substantially through the bearings.   
     
     
         12 . The system of  claim 8 , wherein the roll comprises one of a set of counter-rotating rolls, the counter-rotating rolls configured to compress a web of material. 
     
     
         13 . The system of  claim 12 , wherein:
 an induction heating actuator comprises the induction heating workcoil and a power source coupled to at least one coil of the induction heating workcoil; and   the system further comprises a controller configured to control the power source to control an amount of compression provided by at least a portion of the counter-rotating rolls.   
     
     
         14 . The system of  claim 8 , wherein multiple induction heating workcoils are located adjacent to each other in a row proximate to the roll. 
     
     
         15 . The system of  claim 14 , wherein multiple rows of induction heating workcoils are located adjacent to each other proximate to the roll. 
     
     
         16 . A method comprising:
 placing an induction heating workcoil in proximity with a roll, the roll configured to rotate about an axis, the induction heating workcoil comprising an unbalanced induction heating workcoil;   orienting the induction heating workcoil so that a magnetic flux path within the roll produced by the unbalanced induction heating workcoil is axially aligned with the axis of the roll; and   producing currents within the roll.   
     
     
         17 . The method of  claim 16 , further comprising:
 initially orienting the induction heating workcoil so that the magnetic flux path is not axially aligned with the axis of the roll, before orienting the induction heating workcoil so that the magnetic flux path is axially aligned with the axis of the roll.   
     
     
         18 . The method of  claim 16 , wherein:
 the roll comprises a shaft and bearings; and   orienting the induction heating workcoil comprises orienting the induction heating workcoil so that the currents do not flow substantially through the bearings.   
     
     
         19 . The method of  claim 16 , wherein the roll comprises one of a set of counter-rotating rolls, the counter-rotating rolls configured to compress a web of material. 
     
     
         20 . The method of  claim 19 , wherein:
 an induction heating actuator comprises the induction heating workcoil and a power source coupled to at least one coil of the induction heating workcoil; and   further comprising controlling the power source to control an amount of compression provided by at least a portion of the counter-rotating rolls.