Forming apparatus and method
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.
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.