SYSTEM, APPARATUS, AND METHOD FOR INDUCTION HEATING USING FLUX-BALANCED INDUCTION HEATING WORKCOIL

• US 20090255925A1
• Filed: 04/15/2008
• Published: 10/15/2009
• Est. Priority Date: 04/15/2008
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Crawford, Jonathan, Chirico, Salvatore, Dohmeier, Nicholas
• Granted Patent: US 8,415,595 B2
• Time in Patent Office: Days
• US Class Current: 219/674
• CPC Class Codes: H05B 6/104 metal pieces being elongated like wires or bands
• CPC Class Codes: H05B 6/145 Heated rollers
• CPC Class Codes: H05B 6/365 using supplementary conductive or ferromagnetic pieces
• CPC Class Codes: H05B 6/42 Cooling of coils

Abstract

An apparatus includes one or more magnetic cores collectively having an inner leg located between two outer legs. The legs are coupled to one or more connecting portions. The apparatus also includes one or more conductive coils wound around the inner leg. The one or more magnetic cores and the one or more conductive coils are configured to generate substantially balanced magnetic fluxes when the conductive coil is energized. Also, the one or more magnetic cores and the one or more conductive coils are configured so that heat created by currents induced in the roll by the magnetic fluxes produces a steady state thermal profile on a surface of the roll. The steady state thermal profile has one peak that falls within a control zone associated with the roll. The one or more magnetic cores could include a single magnetic core or multiple magnetic cores.

Claims

1. An apparatus comprising:

one or more magnetic cores collectively comprising an inner leg located between two outer legs, the legs coupled to one or more connecting portions; and

one or more conductive coils wound around the inner leg;

wherein the one or more magnetic cores and the one or more conductive coils are configured to generate substantially balanced magnetic fluxes within a roll when the one or more conductive coils are energized; and

wherein the one or more magnetic cores and the one or more conductive coils are configured so that heat created by currents induced in the roll by the magnetic fluxes produces a steady state thermal profile on a surface of the roll, the steady state thermal profile having one peak that falls within a control zone associated with the roll.

2. The apparatus of claim 1, wherein substantially all of the magnetic fluxes are generated within the control zone associated with the roll.

3. The apparatus of claim 1, wherein the one or more magnetic cores comprise a single magnetic core, the single magnetic core comprising a single connecting portion coupling the inner and outer legs.

4. The apparatus of claim 1, wherein the one or more magnetic cores comprise two magnetic cores, each magnetic core comprising two legs, the inner leg comprising one leg from each of the magnetic cores.

5. The apparatus of claim 1, further comprising:

a second coil wound around the one or more conductive coils and configured to cool at least one of;

the one or more magnetic cores and the one or more conductive coils.

6. The apparatus of claim 1, further comprising:

a heatsink attached to the core and configured to release thermal energy generated when the one or more conductive coils are energized.

7. The apparatus of claim 6, further comprising:

a thermal shunt configured to provide thermal energy from at least one of the one or more magnetic cores and the one or more conductive coils to the heatsink.

8. A system comprising:

a roll comprising a conductive material, the roll configured to rotate about an axis; and

an induction heating workcoil comprising;

one or more magnetic cores collectively comprising an inner leg located between two outer legs, the legs coupled to one or more connecting portions; and

one or more conductive coils wound around the inner leg;

wherein the one or more magnetic cores and the one or more conductive coils are configured to generate magnetic fluxes within the roll, wherein the magnetic fluxes travel substantially perpendicular to the axis of the roll, and wherein the magnetic fluxes when spatially summed have a substantially null instantaneous magnetic flux vector.

9. The system of claim 8, wherein the one or more magnetic cores and the one or more conductive coils are configured so that heat created by currents induced in the roll by the magnetic fluxes produces a steady state thermal profile on a surface of the roll, the steady state thermal profile having one peak that falls within a control zone associated with the roll.

10. The system of claim 8, wherein the one or more magnetic cores comprise a single magnetic core, the single magnetic core comprising a single connecting portion coupling the inner and outer legs.

11. The system of claim 8, wherein the one or more magnetic cores comprise two magnetic cores, each magnetic core comprising two legs, the inner leg comprising one leg from each of the magnetic cores.

12. The system of claim 8, further comprising:

a mounting plate on which the workcoil is mounted, the mounting plate comprising curved slots allowing rotation of the workcoil.

13. 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;

an induction heating actuator comprises the induction heating workcoil and a power source coupled to the one or more conductive coils; and

the system further comprises a controller configured to control the power source in the actuator to control an amount of compression provided by at least a portion of the counter-rotating rolls.

14. A method comprising:

placing an induction heating workcoil in proximity with a roll, wherein the induction heating workcoil comprises one or more magnetic cores and one or more conductive coils, the one or more magnetic cores collectively comprising an inner leg located between two outer legs, the one or more conductive coils wound around the inner leg, the roll configured to rotate about an axis; and

generating currents within the roll, the currents collectively having a substantially null instantaneous current vector and flowing substantially parallel to the axis of the roll.

15. The method of claim 14, wherein heat created by the currents produces a steady state thermal profile on a surface of the roll, the steady state thermal profile having one peak that falls within a control zone associated with the roll.

16. The method of claim 14, wherein the one or more magnetic cores comprise a single magnetic core, the single magnetic core comprising a single connecting portion coupling the inner and outer legs.

17. The method of claim 14, wherein the one or more magnetic cores comprise two magnetic cores, each magnetic core comprising two legs, the inner leg comprising one leg from each of the magnetic cores.

18. The method of claim 14, wherein the induction heating workcoil comprises at least one of:

a reinforcing material around ends of the legs of the one or more cores; and

a protective enclosure encasing at least the legs of the one or more cores.

19. The method of claim 14, wherein:

the roll comprises one of a set of counter-rotating rolls, the counter-rotating rolls configured to compress a web of material;

an induction heating actuator comprises the induction heating workcoil and a power source coupled to the one or more conductive coils; and

further comprising controlling the power source to control an amount of compression provided by at least a portion of the counter-rotating rolls.

20. The method of claim 19, wherein:

multiple induction heating actuators are associated with multiple zones of at least one of the counter-rotating rolls; and

controlling the power source comprises controlling the power source in each actuator to control an amount of compression provided in each zone.