Field-stabilized induction heating

Patent metadata

Field	Value
Publication number	US-2016344152-A1
Application number	US-201514720045-A
Country	US
Kind code	A1
Filing date	May 22, 2015
Priority date	May 22, 2015
Publication date	Nov 24, 2016
Grant date	—

Abstract

Methods and systems for the uniform induction heating of forming dies, where the forming die may be heated by an induction coil in conjunction with a pair of electromagnetic (EM) field stabilizers, each EM field stabilizer configured to be adjacent one end of the forming die while the forming die is within the induction heating coil.

First claim

We claim:

1 . A system for heating a forming die, the system comprising:
an induction coil configured to surround the forming die and heat the forming die by generating an electromagnetic field within the forming die; and a pair of electromagnetic (EM) field stabilizers, each configured to be adjacent an end of the forming die while the forming die is within the induction coil, the pair of EM field stabilizers being further configured to create a substantially uniform magnetic field within the forming die as the forming die is heated by the induction coil.

2 . The system of claim 1 , wherein each EM field stabilizer includes a plurality of stabilizer plates separated by a non-metallic spacer material, where each stabilizer plate includes a magnetic material, and wherein each EM field stabilizer is configured so that the planes of the stabilizer plates are at least substantially parallel to a long axis of the induction coil when adjacent an end of the forming die.

3 . The system of claim 2 , wherein the non-metallic spacer material comprises at least one of air, foam, wood, and paper.

4 . The system of claim 1 , wherein each stabilizer plate comprises a ferrite sheet.

5 . The system of claim 1 , wherein each EM field stabilizer comprises a number of stabilizer plates to create the substantially uniform magnetic field while the induction coil generates the electromagnetic field.

6 . The system of claim 5 , wherein each EM field stabilizer comprises from 4-20 stabilizer plates.

7 . The system of claim 1 , wherein each EM field stabilizer is disposed within 1/16 inch (1.6 mm) of a respective end of the forming die.

8 . A joggle die assembly comprising:
an elongate conductive joggle die having a long axis; and an EM field stabilizer adjacent each end of the elongate joggle die, wherein
each field stabilizer includes a plurality of stabilizer plates, each stabilizer plate being magnetic; and
each field stabilizer is disposed so that the planes of the stabilizer plates are oriented with respect to the long axis of the elongate conductive joggle die.

9 . The joggle die assembly of claim 8 , wherein the stabilizer plates are substantially equidistantly spaced from each other and separated by a non-metallic spacer material.

10 . The joggle die assembly of claim 8 , wherein each stabilizer plate is substantially parallel to the other stabilizer plates, and the planes of the stabilizer plates are substantially parallel to the long axis of the elongate conductive joggle die.

11 . The joggle die assembly of claim 8 , wherein the elongate joggle die comprises a steel alloy, and is configured to be used in combination with a joggle press to form a joggle in a structure.

12 . The joggle die assembly of claim 11 , wherein the elongate joggle die is configured to form a joggle in a stringer for use in the manufacture of an aircraft.

13 . A method of induction heating, the method comprising:
placing a conductor within an induction coil; placing an EM field stabilizer adjacent each of the opposing ends of the conductor; and applying current to the induction coil to heat the conductor; wherein the EM field stabilizers create a substantially uniform magnetic field within the conductor as the conductor is heated by the induction coil.

14 . The method of claim 13 , wherein placing the conductor within the induction coil comprises placing a forming die that is the conductor within the induction coil.

15 . The method of claim 13 , wherein placing an EM field stabilizer includes placing a plurality of stabilizer plates adjacent each end of the conductor such that planes of the stabilizer plates are oriented with respect to the long axis of the conductor, and wherein each stabilizer plate is magnetic.

16 . A method of forming a joggle bend in a structure, the method comprising:
placing an elongate conductive joggle die within an induction coil; placing a field stabilizer adjacent each end of the elongate conductive joggle die; applying current to the induction heating coil so as to induce substantially uniform heating in the elongate conductive joggle die for a time sufficient to heat the elongate conductive joggle die to at least a first predetermined temperature; placing the heated elongate conductive joggle die in a joggle press; placing the structure in the heated elongate conductive joggle die; and forming the joggle bend in the structure by compressing the heated elongate conductive joggle die in the joggle press.

17 . The method of claim 16 , wherein placing a field stabilizer adjacent each end of the elongate conductive joggle die includes placing a field stabilizer having a plurality of stabilizer plates separated by a non-metallic spacer material, each stabilizer plate being substantially magnetic, each field stabilizer being disposed so that the planes of the stabilizer plates are approximately parallel to the long axis of the induction coil.

18 . The method of claim 16 , wherein applying current to the induction heating coil induces heating in the elongate conductive joggle die to a substantially uniform temperature that varies by less than about +/−10 degrees F. (+/−5.6 degrees C.) along a length of the elongate conductive joggle die.

19 . The method of claim 16 , wherein heating the elongate conductive joggle die to at least the first predetermined temperature requires no more than 10 minutes.

20 . The method of claim 16 , wherein applying sufficient current includes applying current for a time that heats the elongate conductive joggle die to at least a second predetermined temperature higher than the first predetermined temperature.

Assignees

• Boeing Co

Inventors

• Chen Cameron Kai-Ming
• Matsen Marc R
• Miller Robert James
• Billings Scott David

Classifications

• H05B6/365

  using supplementary conductive or ferromagnetic pieces · CPC title

• Y10T29/49078

  Laminated · CPC title

• H01F41/046

  structurally combined with ferromagnetic material · CPC title

• Y10T29/49075

  including permanent magnet or core · CPC title

• H05B6/10

  Induction heating apparatus, other than furnaces, for specific applications · CPC title