System for adjusting the equilibrium temperature of an inductively-heated susceptor

• US 10,442,120 B2
• Filed: 01/17/2015
• Issued: 10/15/2019
• Est. Priority Date: 11/28/2011
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Matsen, Marc R., Negley, Mark A., Geren, William Preston
• Primary Examiner(s): Abraham, Ibrahime A
• Assistant Examiner(s): Bae, Gyounghyun
• Application Number:
  US14/599,475
• Publication Number:
  US 20190134863A1
• Time in Patent Office: 1,732 Days
• Field of Search: None
• CPC Class Codes: B29C 2035/0811 using induction
• CPC Class Codes: B29C 33/06 using radiation , e.g. electro-magnetic waves, induction heating
• CPC Class Codes: B29C 43/52 Heating or cooling
• CPC Class Codes: H05B 2206/023 using the curie point of the material in which heating current is being generated to control the heating temperature
• CPC Class Codes: H05B 6/105 using a susceptor

Abstract

A system for inductively heating a workpiece may include an induction coil, at least one susceptor face sheet, and a current controller coupled. The induction coil may be configured to conduct an alternating current and generate a magnetic field in response to the alternating current. The susceptor face sheet may be configured to have a workpiece positioned therewith. The susceptor face sheet may be formed of a ferromagnetic alloy having a Curie temperature and being inductively heatable to an equilibrium temperature approaching the Curie temperature in response to the magnetic field. The current controller may be coupled to the induction coil and may be configured to adjust the alternating current in a manner causing a change in at least one heating parameter of the susceptor face sheet.

Claims

1. A system for inductively heating a workpiece, comprising:

an induction coil configured to conduct an alternating current and generate a magnetic field in response to the alternating current, the magnetic field having flux lines oriented generally perpendicularly relative to a direction of the alternating current flowing through the induction coil;

an upper susceptor face sheet and a lower susceptor face sheet inductively heated by the induction coil and configured to have a workpiece positioned therebetween, the upper susceptor face sheet and the lower susceptor face sheet being formed of a ferromagnetic alloy having a Curie temperature and being inductively heatable to an equilibrium temperature approaching the Curie temperature in response to the magnetic field; and

a current controller coupled to the induction coil and configured to adjust a frequency of the alternating current as a means to shift the equilibrium temperature of the upper susceptor face sheet and/or the lower susceptor face sheet, the current controller being configured, upon attainment of an initial magnetic permeability of the upper susceptor face sheet and the lower susceptor face sheet corresponding to a first equilibrium temperature in the upper susceptor face sheet and the lower susceptor face sheet relative to the Curie temperature, to increase the frequency of the alternating current to cause a reduction in the magnetic permeability of the upper susceptor face sheet and the lower susceptor face sheet resulting in an increase in a concentration of the alternating current to a current density of greater than 1×

10⁷ amps/meters² and less than or equal to 4×

10⁷ amps/meter² along an outer surface of the upper susceptor face sheet and the lower susceptor face sheet and a corresponding increase in the equilibrium temperature from the first equilibrium temperature of the upper susceptor face sheet and the lower susceptor face sheet to a second equilibrium temperature of the upper susceptor face sheet and the lower susceptor face sheet relative to the Curie temperature.

2. The system of claim 1 wherein:

the current controller is configured to adjust the frequency of the alternating current causing the equilibrium temperature of the upper susceptor face sheet and the lower susceptor face sheet to shift by 5 to 15 degrees Fahrenheit.

3. The system of claim 1 wherein:

the current controller is configured to adjust an amperage of the alternating current causing a change in a rate of heating of the upper susceptor face sheet and the lower susceptor face sheet.

4. The system of claim 1 wherein:

the alternating current has a frequency range of from 1 kHz to 300 kHz.

5. The system of claim 1 wherein:

the alternating current has an amperage of between 10 amps and 10,000 amps.

6. The system of claim 1 wherein:

the induction coil comprises a plurality of upper and lower coil portions extending through a plurality of laminations.

7. The system of claim 1 wherein:

the induction coil comprises an upper die coil portion and a lower die coil portion; and

the upper and lower die coil portions being electrically coupled to one another to form an induction coil when a workpiece is clamped between the upper susceptor face sheet and the lower susceptor face sheet.

8. The system of claim 1 further comprising:

a cooling system for cooling the upper susceptor face sheet and the lower susceptor face sheet.

9. The system of claim 1 further comprising:

a press for applying a compressive force to the workpiece.

10. A system for inductively heating a workpiece, comprising:

an induction coil configured to conduct an alternating current and generate a magnetic field in response to the alternating current, the magnetic field having flux lines oriented generally perpendicularly relative to a direction of the alternating current flowing through the induction coil;

an upper susceptor face sheet and a lower susceptor face sheet inductively heated by the induction coil and configured to have a workpiece positioned therebetween, each one of the upper susceptor face sheet and the lower susceptor face sheet having opposing outer surfaces and an interior portion between the opposing outer surfaces and being formed of a ferromagnetic alloy having a Curie temperature and being inductively heatable to an equilibrium temperature approaching the Curie temperature in response to the magnetic field; and

a current controller coupled to the induction coil and configured to adjust a frequency of the alternating current as a means to shift the equilibrium temperature of the upper susceptor face sheet and/or the lower susceptor face sheet, the current controller being configured, upon attainment of an initial magnetic permeability of the upper susceptor face sheet and the lower susceptor face sheet corresponding to a first equilibrium temperature in the upper susceptor face sheet and the lower susceptor face sheet relative to the Curie temperature, to increase the frequency of the alternating current to cause a reduction in the magnetic permeability of the upper susceptor face sheet and the lower susceptor face sheet resulting in, at a temperature below the Curie temperature, at least one of the upper susceptor face and the lower susceptor face sheet has a current density of 3-4×

10⁷ Ampere/meter² adjacent to at least one of the opposing outer surfaces, a current density of 0-2×

10⁷ Ampere/meter² in the interior portion, and a current density of 2-3×

10⁷ Ampere/meter² between the interior portion and the at least one of the opposing outer surfaces, and a corresponding increase in the equilibrium temperature from the first equilibrium temperature of the upper susceptor face sheet and the lower susceptor face sheet to a second equilibrium temperature of the upper susceptor face sheet and the lower susceptor face sheet relative to the Curie temperature.

11. The system of claim 10 wherein:

the current controller is configured to adjust the frequency of the alternating current causing the equilibrium temperature of the upper susceptor face sheet and the lower susceptor face sheet to shift by 5 to 15 degrees Fahrenheit.

12. The system of claim 10 wherein:

the current controller is configured to adjust an amperage of the alternating current causing a change in a rate of heating of the upper susceptor face sheet and the lower susceptor face sheet.

13. The system of claim 10 wherein:

the alternating current has a frequency range of from 1 kHz to 300 kHz.

14. The system of claim 10 wherein:

the alternating current has an amperage of between 10 amps and 10,000 amps.

15. A system for inductively heating a workpiece, comprising:

an induction coil configured to conduct an alternating current and generate a magnetic field in response to the alternating current, the magnetic field having flux lines oriented generally perpendicularly relative to a direction of the alternating current flowing through the induction coil;

an upper susceptor face sheet and a lower susceptor face sheet inductively heated by the induction coil and configured to have a workpiece positioned therebetween, the upper susceptor face sheet and the lower susceptor face sheet being formed of a ferromagnetic alloy having a Curie temperature and being inductively heatable to an equilibrium temperature approaching the Curie temperature in response to the magnetic field;

a current controller coupled to the induction coil and configured to adjust a frequency of the alternating current as a means to shift the equilibrium temperature of the upper susceptor face sheet and/or the lower susceptor face sheet, the current controller being configured, upon attainment of an initial magnetic permeability of the upper susceptor face sheet and the lower susceptor face sheet corresponding to a first equilibrium temperature in the upper susceptor face sheet and the lower susceptor face sheet relative to the Curie temperature, to increase the frequency of the alternating current to cause a reduction in the magnetic permeability of the upper susceptor face sheet and the lower susceptor face sheet resulting in an increase in a concentration of the alternating current to a current density in a range of 0-4×

10⁷ amps/meter² along an outer surface of the upper susceptor face sheet and the lower susceptor face sheet and a corresponding increase in the equilibrium temperature from the first equilibrium temperature of the upper susceptor face sheet and the lower susceptor face sheet to a second equilibrium temperature of the upper susceptor face sheet and the lower susceptor face sheet relative to the Curie temperature; and

the current controller is configured, upon attainment of the initial magnetic permeability of the upper susceptor face and the lower susceptor face sheet of 500, to reduce the magnetic permeability of the upper susceptor face and the lower susceptor face sheet to a magnetic permeability of 250 by increasing the frequency of the alternating current.