Abstract:
An induction brazing uses a multisheet, diaphagm retort having isolated pressure zones to control the net tooling pressure at a level that avoids core crush. The isolated chambers in the multisheet diaphragm allow us to apply controlled pressure to the braze joint, especially at the elevated brazing temperature where the honeycomb core is soft and malleable.
Abstract:
The processing time and energy efficiency of metal or composite bonding operations is improved by heating the lay-up preform of the structure in an induction heating press where energy goes primarily to heating the workpieces rather than to heating the tooling or being lost to the environment. The bonding process is especially beneficial for joining thermoplastic composites, but it also can be used with metals or thermosets. Preferential heating at the bondline is achieved by using shims to define the bondline and to define bead regions that have relief from contact with the susceptor envelope because of the thickness of the shims in the bondline regions.
Abstract:
The processing time and energy efficiency of metal or composite bonding operations is improved by heating the lay-up preform of the structure in an induction heating press where energy goes primarily to heating the workpieces rather than to heating the tooling or being lost to the environment. The bonding process is especially beneficial for joining thermoplastic composites, but it also can be used with metals or thermosets. Preferential heating at the bondline is achieved by using shims to define the bondline and to define bead regions that have relief from contact with the susceptor envelope because of the thickness of the shims in the bondline regions.
Abstract:
If internal support is required to keep thermoplastic parts from sagging during thermoplastic welding, silicone rubber bladder inflated to fill the space between the prefabricated composite parts, such as wingskins and spaced spars, provides positive reaction pressure. To protect the bladder we cover the sharp edges at the interface of the parts with foam or silicone rubber pads.
Abstract:
A die for use in an induction heating workcell incorporates segments of the induction coil in spaced array within a cast ceramic or phenolic body. A peripheral compression frame, typically of phenolic, surrounds the die body and applies a compressive load to the body through lateral and transverse reinforcing rods that are cast into the body. Matched dies close to trap heat in a workpiece at the center of the induction coil.
Abstract:
For forming or consolidating organic matrix composites, for example, an organic matrix composite panel is sealed in a "retort" 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.
Abstract:
A method and apparatus for forming and consolidating organic matrix composites. An organic matrix composite panel comprising laid-up prepregs is placed between sheets of a susceptor material that is susceptible to inductive heating to form a workpiece. The resulting workpiece is placed within upper and lower dies formed of a material that is not susceptible to inductive heating. An induction coil embedded within the dies is energized and inductively heats the susceptor sheets surrounding the panel. The sheets in turn conductively heat the organic matrix composite panel. A pressure zone between the workpiece and one of the dies is pressurized to form the workpiece to the contour of a forming surface on one of the dies. The pressure in the pressure zone is maintained on the workpiece until the organic matrix composite panel is fully consolidated and formed.
Abstract:
Multisheet SPF parts with braze joints at selected locations are produced with improved energy efficiency and at lower cost by heating the multisheet pack to its superplastic forming range below the melting point of the braze alloy, superplastically forming the pack to define braze joints having unmelted braze alloy; increasing the temperature to the braze temperature of the braze alloy, and cooling the pack below the superplastic range to freeze the braze alloy in the braze joint.
Abstract:
A metal matrix composite is made by roll consolidating a sandwich formed from alternating layers of a matrix metal, a brazing alloy, and reinforcing fiber at elevated temperature and pressure. If made in a process using mandrels to impart the pressure and heat, such as a process described in U.S. Pat. No. 5,229,562, the metal matrix composite is kept separate from the mandrels by using a release agent or stop-off such as a layer of boron nitride between the mandrel and layup.
Abstract:
A thermoplastic welding apparatus includes a thermoplastic welding tool, at least one tooling surface in the thermoplastic welding tool, a magnetic induction coil in the thermoplastic welding tool and generally encircling the at least one tooling surface and at least one smart susceptor in the thermoplastic welding tool at the at least one tooling surface. The magnetic induction coil is adapted to generate a magnetic flux field oriented generally parallel to a plane of the at least one smart susceptor.