Forming apparatus and method

• US 20050035115A1
• Filed: 08/13/2003
• Published: 02/17/2005
• Est. Priority Date: 08/13/2003
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Matsen, Marc R., McCarville, Douglas A., Anderson, Donald A., Moore, Stephen G., Kirkwood, Brad L., Brown, Ronald W.
• Granted Patent: US 6,979,807 B2
• Time in Patent Office: Days
• US Class Current: 219/759
• CPC Class Codes: B29C 2035/0811 using induction
• CPC Class Codes: B29C 2035/0816 using eddy currents
• CPC Class Codes: B29C 2035/1616 using liquids
• CPC Class Codes: B29C 33/04 using liquids, gas or steam tyre moulds with incorporated heating or cooling means using liquids, gas or steam B29D30/0601
• CPC Class Codes: B29C 33/046 using gas
• CPC Class Codes: B29C 33/06 using radiation , e.g. electro-magnetic waves, induction heating
• CPC Class Codes: B29C 35/0805 using electromagnetic radiation
• 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 70/54 Component parts, details or accessories; Auxiliary operations , e.g. feeding or storage of prepregs or SMC after impregnation or during ageing
• 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

An apparatus and method for forming a composite workpiece are provided. An electromagnetic field generator induces a current in a susceptor, thereby heating the workpiece in a die cavity. An elastomeric bladder in the cavity is inflated and urges the workpiece against a contour surface corresponding to a desired configuration of the workpiece. Coolant fluid can also be circulated through the die cavity to cool the workpiece. Thus, the workpiece can be heated, formed, and cooled quickly and without substantial heating of other components, thereby reducing the time and energy relative to conventional forming methods.

Claims

1. An apparatus for forming a composite workpiece to a desired configuration, the apparatus comprising:

first and second co-operable dies structured to define a die cavity therebetween for at least partially receiving the workpiece, at least one of said dies defining a contour surface corresponding to the desired configuration of the workpiece;

at least one susceptor in thermal communication with said die cavity, at least a portion of said at least one susceptor comprised of a conductive material for supporting current flow and thereby heating the workpiece to a forming temperature;

an elastomeric bladder positioned in said die cavity, said bladder configured to receive a pressurized fluid for expanding said bladder and thereby urge the workpiece against said contour surface and form the workpiece to the desired configuration; and

a coolant source configured to circulate a coolant fluid through said die cavity and thereby cool the workpiece.

2. An apparatus according to claim 1 further comprising a thermally insulative material disposed on an outer surface of said bladder.

3. An apparatus according to claim 1 wherein said at least one susceptor is characterized by a Curie temperature at which said susceptor becomes paramagnetic.

4. An apparatus according to claim 3 wherein the Curie temperature of said at least one susceptor is about equal to the forming temperature of the workpiece.

5. An apparatus according to claim 1 further comprising an induction coil extending around the workpiece and said susceptor, said induction coil being configured to generate an electromagnetic field when energized by a power supply, thereby inducing a current within at least a portion of said at least one susceptor and heating the workpiece to the forming temperature.

6. An apparatus according to claim 5 further comprising a fluid source fluidly connected to a passage defined by said at least one induction coil and configured to circulate a cooling fluid through said passage and thereby cool said at least one induction coil.

7. An apparatus according to claim 1 wherein said coolant source is configured to circulate the coolant fluid through said bladder, thereby cooling said bladder.

8. An apparatus according to claim 1 wherein said bladder comprises at least one of the group consisting of rubber and silicone elastomer.

9. An apparatus according to claim 1 further comprising an inflatable susceptor engagement seal disposed at an interface of first and second portions of the at least one susceptor, said susceptor engagement seal configured to inflate and thereby electrically engage the first and second portions.

10. An apparatus according to claim 1 further comprising an inflatable cavity seal disposed at an interface of said first and second dies, said cavity seal configured to receive a pressurized fluid to inflate said seal and thereby hermetically seal said die cavity.

11. An apparatus according to claim 1 further comprising a foil disposed around the workpiece to form a space configured to be fluidly evacuated, thereby urging said foil toward the workpiece.

12. An apparatus according to claim 1 wherein said susceptor is disposed on said contour surface and said susceptor and said contour surface define at least one channel therebetween for receiving a coolant fluid.

13. An apparatus according to claim 12 wherein said coolant source is fluidly connected to said at least one channel and configured to circulate the coolant fluid through said at least one channel.

14. An apparatus according to claim 1 further comprising a heat exchanger, wherein said coolant source is configured to circulate the coolant fluid through said heat exchanger, such that the coolant fluid is heated in said die cavity and cooled in said heat exchanger.

15. An apparatus for forming a composite workpiece to a desired configuration, the apparatus comprising:

first and second co-operable dies structured to define a die cavity therebetween for at least partially receiving the workpiece, at least one of said dies defining a contour surface corresponding to the desired configuration of the workpiece;

at least one susceptor disposed in said die cavity, at least a portion of said at least one susceptor comprised of a conductive material for supporting current flow and thereby heating the workpiece to a forming temperature, said susceptor and at least one of said dies defining at least one channel therebetween for receiving a coolant fluid;

an elastomeric bladder positioned in said die cavity, said bladder configured to receive a pressurized fluid for expanding said bladder and thereby urge the workpiece against said contour surface and form the workpiece to the desired configuration; and

a coolant source fluidly connected to said at least one channel and configured to circulate a coolant fluid through said at least one channel and thereby cool the workpiece.

16. An apparatus according to claim 15 further comprising a thermally insulative material disposed on an outer surface of said bladder.

17. An apparatus according to claim 15 wherein said at least one susceptor is characterized by a Curie temperature at which said susceptor becomes paramagnetic.

18. An apparatus according to claim 17 wherein the Curie temperature of said at least one susceptor is about equal to the forming temperature of the workpiece.

19. An apparatus according to claim 15 further comprising an induction coil extending around the workpiece and said susceptor, said induction coil being configured to generate an electromagnetic field when energized by a power supply, thereby inducing a current within at least a portion of said at least one susceptor and heating the workpiece to the forming temperature.

20. An apparatus according to claim 19 further comprising a fluid source fluidly connected to a passage defined by said at least one induction coil and configured to circulate a cooling fluid through said passage and thereby cool said at least one induction coil.

21. An apparatus according to claim 15 wherein said bladder comprises at least one of the group consisting of rubber and silicone elastomer.

22. An apparatus according to claim 15 further comprising an inflatable susceptor engagement seal disposed at an interface of first and second portions of the at least one susceptor, said susceptor engagement seal configured to inflate and thereby electrically engage the first and second portions.

23. An apparatus according to claim 15 further comprising an inflatable cavity seal disposed at an interface of said first and second dies, said cavity seal configured to receive a pressurized fluid to inflate said seal and thereby hermetically seal said die cavity.

24. An apparatus according to claim 15 further comprising a foil disposed around the workpiece to form a space configured to be fluidly evacuated, thereby urging said foil toward the workpiece.

25. An apparatus according to claim 15 further comprising a heat exchanger, wherein said coolant source is configured to circulate the coolant fluid through said heat exchanger, such that the coolant fluid is heated in said die cavity and cooled in said heat exchanger.

26. An apparatus according to claim 15 wherein a first susceptor is disposed against the first die and a second susceptor is disposed against the second die, the first die and the first susceptor defining a plurality of said channels therebetween and the second die and the second susceptor defining a plurality of said channels therebetween.

27. A method for forming a composite workpiece, the method comprising:

providing the workpiece at least partially in a die cavity;

positioning at least one elastomeric bladder in the die cavity proximate to the workpiece;

inducing a current within at least a portion of at least one susceptor, thereby heating the workpiece to a forming temperature;

injecting a pressurized fluid into the bladder and thereby expanding the bladder to form the workpiece to a predetermined configuration; and

circulating a coolant fluid through the die cavity and thereby cooling the workpiece subsequent to said injecting step.

28. A method according to claim 27 wherein said providing step comprises providing a plurality of layered fibrous mats and resin films to form the workpiece.

29. A method according to claim 27 wherein said providing step comprises providing a composite workpiece blank having a fibrous material and a matrix material.

30. A method according to claim 27 wherein said inducing step comprises heating the susceptor to a Curie temperature at which the susceptor becomes paramagnetic.

31. A method according to claim 27 wherein said inducing step comprises heating the workpiece to a temperature of between about 600°

F. and 900°

F. during a time interval of between about 10 and 60 seconds.

32. A method according to claim 27 wherein said injecting step comprises pressurizing the bladder to between about 200 and 400 psi.

33. A method according to claim 27 wherein said circulating step comprises circulating the coolant fluid through at least one channel defined between one of the dies and the susceptor disposed thereon.

34. A method according to claim 27 further comprising circulating a cooling fluid though a passage defined by an induction coil extending around the workpiece and the susceptor, and wherein said inducing step comprises electrically energizing the induction coil.

35. A method according to claim 27 wherein said circulating step comprises circulating a pressurized coolant fluid through the bladder, thereby cooling the bladder.

36. A method according to claim 27 further comprising inflating a susceptor engagement seal disposed at an interface of first and second portions of the at least one susceptor and thereby electrically engaging the first and second portions.

37. A method according to claim 27 further comprising engaging first and second co-operable dies to form the die cavity and pressurizing an inflatable cavity seal disposed at an interface of the dies to thereby hermetically seal the die cavity.

38. A method according to claim 27 wherein said providing step comprises disposing a foil around the workpiece.

39. A method according to claim 27 further comprising hermetically sealing the foil and evacuating a space defined within the foil.