Method for achieving thermal uniformity in induction processing of organic matrix composites or metals

• US 5,728,309 A
• Filed: 06/06/1995
• Issued: 03/17/1998
• Est. Priority Date: 04/05/1991
• Status: Expired due to Term

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Woods, Edward J., DeJong, executor, John J., Matsen, Marc R., Hansen, deceased, Karl A.
• Primary Examiner(s): HOANG, TU BA
• Application Number:
  US08/469,604
• Time in Patent Office: 1,015 Days
• Field of Search: 219/604, 219/615, 219/633-635, 219/621, 219/645, 219/608, 219/609, 72/60, 72/70
• US Class Current: 219/633
• CPC Class Codes: B21D 26/021 Deforming sheet bodies
• CPC Class Codes: B21D 26/025 Means for controlling the clamping or opening of the moulds
• CPC Class Codes: B21D 26/053 characterised by the material of the blanks
• CPC Class Codes: B21D 26/055 Blanks having super-plastic properties
• CPC Class Codes: B22F 2003/1046 with separating means for articles to be sintered
• CPC Class Codes: B22F 2003/1053 by induction
• CPC Class Codes: B22F 2998/00 Supplementary information concerning processes or compositions relating to powder metallurgy
• CPC Class Codes: B22F 3/105 by using electric current other than for infrared radiant energy, laser radiation or plasma B22F3/11 takes precedence; by ultrasonic bonding B22F3/115 takes precedence
• CPC Class Codes: B22F 3/18 by using pressure rollers
• CPC Class Codes: B23K 20/023 Thermo-compression bonding
• CPC Class Codes: B23K 2101/18 Sheet panels
• CPC Class Codes: B29C 2035/0811 using induction
• CPC Class Codes: B29C 2043/3233 exerting pressure on mould parts
• CPC Class Codes: B29C 2043/3655 Pressure transmitters, e.g. caul plates; pressure pads
• CPC Class Codes: B29C 2043/5808 pressure or compressing force
• CPC Class Codes: B29C 33/06 using radiation , e.g. electro-magnetic waves, induction heating
• CPC Class Codes: B29C 33/08 for dielectric heating
• CPC Class Codes: B29C 33/60 Releasing, lubricating or separating agents in general C10M
• CPC Class Codes: B29C 35/08 by wave energy or particle radiation B29C64/00, B29C71/04 take precedence
• CPC Class Codes: B29C 43/10 Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies
• CPC Class Codes: B29C 43/3642 : Bags, bleeder sheets or cauls for isostatic pressing
• CPC Class Codes: B29C 43/52 : Heating or cooling
• CPC Class Codes: B29C 65/14 : using wave energy , i.e. electromagnetic radiation, or particle radiation using mechanical waves B29C65/06; using ultrasonic waves B29C65/08; pressing means transparent to electromagnetic radiation B29C66/81267
• CPC Class Codes: B29C 65/18 : using heated tools
• CPC Class Codes: B29C 65/32 : Induction
• CPC Class Codes: B29C 65/34 : using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
• CPC Class Codes: B29C 65/3476 : being metallic
• CPC Class Codes: B29C 65/3644 : being a ribbon, band or strip
• CPC Class Codes: B29C 65/3668 : characterised by the means for supplying heat to said heated elements which remain in the join, e.g. special induction coils
• CPC Class Codes: B29C 65/3676 : being metallic
• CPC Class Codes: B29C 65/368 : with a polymer coating
• CPC Class Codes: B29C 66/54 : Joining several hollow-preforms, e.g. half-shells, to form hollow articles, e.g. for making balls, containers; Joining several hollow-preforms, e.g. half-cylinders, to form tubular articles
• CPC Class Codes: B29C 66/634 : using an inflatable core
• CPC Class Codes: B29C 66/71 : characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/721 : Fibre-reinforced materials B29C66/729 takes precedence
• CPC Class Codes: B29C 66/7392 : characterised by the material of at least one of the parts being a thermoplastic
• CPC Class Codes: B29C 66/73921 : characterised by the materials of both parts being thermoplastics
• CPC Class Codes: B29C 66/7394 : characterised by the material of at least one of the parts being a thermoset
• CPC Class Codes: B29C 66/73941 : characterised by the materials of both parts being thermosets
• CPC Class Codes: B29C 66/8122 : characterised by the composition of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps
• CPC Class Codes: B29C 66/81241 : being porous or sintered
• CPC Class Codes: B29C 66/81261 : Thermal properties, e.g. thermal conductivity, thermal expansion coefficient
• CPC Class Codes: B29C 66/81811 : of the welding jaws
• CPC Class Codes: B29C 66/81821 : of the welding jaws
• CPC Class Codes: B29C 66/8223 : Worm or spindle mechanisms
• CPC Class Codes: B29C 66/8322 : Joining or pressing tools reciprocating along one axis
• CPC Class Codes: B29C 66/91221 : of the parts to be joined
• CPC Class Codes: B29C 66/91411 : of the parts to be joined, e.g. the joining process taking the temperature of the parts to be joined into account
• CPC Class Codes: B29C 66/91443 : following a temperature-time profile B29C65/38 takes precedence
• CPC Class Codes: B29C 66/91643 : following a heat-time profile B29C65/38 takes precedence
• CPC Class Codes: B29C 66/91651 : by controlling or regulating the heat generated by Joule heating or induction heating
• CPC Class Codes: B29C 66/91655 : by controlling or regulating the current intensity
• CPC Class Codes: B29C 70/44 : using isostatic pressure, e.g. pressure difference-moulding, vacuum bag-moulding, autoclave-moulding or expanding rubber-moulding
• CPC Class Codes: B29C 70/506 : and impregnating by melting a solid material, e.g. sheet, powder, fibres B29C70/508 takes precedence
• CPC Class Codes: B29C 70/542 : Placing or positioning the reinforcement in a covering or packaging element before or during moulding, e.g. drawing in a sleeve
• CPC Class Codes: B29K 2061/00 : Use of condensation polymers of aldehydes or ketones or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2063/00 : Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2071/00 : Use of polyethers , e.g. PEEK, i.e. polyether-etherketone or PEK, i.e. polyetherketone or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2079/08 : PI, i.e. polyimides or derivatives thereof
• CPC Class Codes: B29K 2079/085 : Thermoplastic polyimides, e.g. polyesterimides, PEI, i.e. polyetherimides, or polyamideimides; Derivatives thereof
• CPC Class Codes: B29K 2081/06 : PSU, i.e. polysulfones; PES, i.e. polyethersulfones or derivatives thereof
• CPC Class Codes: B29K 2105/0854 : in the form of a non-woven mat
• CPC Class Codes: B29K 2909/02 : Ceramics
• CPC Class Codes: B32B 2305/024 : Honeycomb
• CPC Class Codes: B32B 2309/62 : Inert
• CPC Class Codes: B32B 2310/0812 : using induction
• CPC Class Codes: B32B 37/06 : characterised by the heating method
• CPC Class Codes: B64C 3/18 : Spars; Ribs; Stringers
• CPC Class Codes: C09K 2205/12 : Hydrocarbons
• CPC Class Codes: C22C 47/00 : Making alloys containing metallic or non-metallic fibres or filaments
• CPC Class Codes: C22C 47/068 : Aligning wires
• CPC Class Codes: C22C 47/20 : by subjecting to pressure and heat an assembly comprising at least one metal layer or sheet and one layer of fibres or filaments
• CPC Class Codes: H05B 6/365 : using supplementary conductive or ferromagnetic pieces
• CPC Class Codes: Y02P 10/25 : Process efficiency
• CPC Class Codes: Y02T 50/40 : Weight reduction

Abstract

For forming or consolidating organic matrix composites, for example, an organic matrix composite panel is sealed between sheets of a susceptor material that is susceptible to induction heating. The susceptor sheets are heated inductively. The sheets in turn conduct heat to the organic matrix composite panel. When heated to the desired temperature, the composite panel is consolidated and/or formed. In the present invention, the susceptor sheets are selected so that their magnetic permeability decreases to unity at approximately the desired operating temperature thereby limiting heating to this "Curie temperature" and providing substantial uniformity of temperature in the panel. Of course, the concept applies to other induction heating operations for metals including SPF, brazing, annealing, heat treating, bonding, hot pressing, and the like.

Claims

1. A method for heating a workpiece in an induction heating operation to achieve substantially uniform heating in the workpiece by using susceptor sheets made from a material that has a Curie temperature, comprising the steps of:

(a) assembling a retort having at least two susceptor sheets sandwiching a workpiece;

(b) temporarily sealing the susceptor sheets to form a sealed retort containing the workpiece in a cavity;

(c) positioning the sealed retort in an induction heating workcell;

(d) substantially uniformly heating the workpiece to substantially the Curie temperature in the workcell by heating the susceptor sheets with induction; and

(e) performing a manufacturing operation on the workpiece substantially at the Curie temperature.

2. The method of claim 1 wherein the susceptor sheets are selected from the group consisting of cobalt alloys, nickel alloys, and iron alloys.

5. The method of claim 1 wherein the susceptor sheets are an alloy having a Curie temperature from about 675°

-2050°

F. (335°

-1120°

C.), the alloy being a cobalt-iron, nickel-iron, iron-silicon, or crystalline or amorphous magnetic alloys.

3. A method for controlling an operating temperature of a workpiece in an induction heating operation, comprising the steps of:

(a) selecting a susceptor having a Curie temperature close to the operating temperature;

(b) energizing an induction coil to induce eddy currents in the susceptor to heat the susceptor to its Curie temperature;

(c) heating the workpiece primarily through conduction from the susceptor;

(d) continuing to energize the coil to keep the susceptor at its Curie temperature while performing an operation on the workpiece.

4. The method of claim 3 wherein the susceptor has a relatively high magnetic permeability at temperatures below its Curie temperature so that the susceptor heats rapidly in a range from ambient temperature to near the Curie temperature.

6. The method of claim 3 wherein the susceptor has a Curie temperature from about 675°

-2050°

F. (355°

-1120°

C.).

7. the method of claim 6 wherein the susceptor is an alloy selected from the group consisting of:

cobalt-iron, nickel-iron, iron-silicon, or amorphous magnetic alloys.

8. The method of claim 3 wherein the susceptor is 35Co-65Fe, 49Co-49Fe-2V, 27Co-Fe3, 3Si-97Fe, 50Ni-50Fe, 79Ni-17Fe-4Mo, 80 Ni-15Fe-5Mo, 5Fe-95Co, 1008 Steel, 42Ni-58Fe, 81Fe-13.5B-3.5Si-2C, 77Fe-16B-2Cr-5Si, or 66Co-4Fe-1Ni-1Si-14B.

9. The method of claim 3 wherein the operation is β

-annealing Ti-6Al-4V, stabilization annealing of Ti alloys, aluminum brazing, superplastic forming, silver brazing of Ti alloys, consolidation or forming of PEEK, consolidation or forming of polyimide, or thermoplastic welding.

10. A method for heating a workpiece in an induction heating operation to a working temperature, comprising the steps of:

(a) selecting a susceptor material susceptible to heating by induction and having a Curie temperature substantially at the working temperature and having a magnetic permeability that falls to unity at the Curie temperature and heating beyond the working temperature ceases;

(b) inductively heating the susceptor to maintain the susceptor substantially at its Curie temperature; and

(c) conducting heat from the susceptor to the workpiece to heat the workpiece to substantially the working temperature.

11. The method of claim 10 wherein the susceptor forms a closed retort that surrounds the workpiece.

12. The method of claim 10 wherein the working temperature is in the range of about 675°

-2050°

F. (355°

-1120°

C.).

13. The method of claim 10 wherein the susceptor is an alloy of Ni, Fe, or Co.

14. The method of claim 10 wherein the working temperature is controlled to a temperature range of about 20°

F. (11°

C.) variation.

15. The method of claim 11 further compromising the step of β

-annealing of Ti-6Al-4V alloy after heating the workpiece to 1930°

±

15°

F., wherein the susceptor is a ductile cobalt alloy.

16. The method of claim 11 further compromising the step of stabilization annealing of Ti-6Al-4V alloy after heating the workpiece to 1400°

±

15°

F., and wherein the susceptor is 1008 steel.

17. The method of claim 10 wherein the processing includes annealing.

18. The method of claim 10 wherein the processing includes brazing.

19. The method of claim 10 wherein the processing includes thermoplastic welding.

20. The method of claim 11 further comprising the step of injecting an inert purging gas to the closed retort around the workpiece.