Fluid tooling for thermoplastic welding

A process for thermoplastic welding a top thermoplastic part to a bottom thermoplastic part along a bond line formed by fused faying surfaces at an interface between the parts, comprising:

• interposing a conductive foraminous susceptor along the interface;
• installing an induction coil in an elongated vessel made of fluid impervious flexible material, said vessel having opposite axial ends and a closure at each end;
• sealing said vessel at both axial ends and filling said vessel with fluid;
• positioning said vessel over said interface and exerting a force along said vessel to press said vessel against said top part;
• applying electrical power to a power lead connected to said coil through a sealed pass-through in said vessel to electrically energize said coil to produce an alternating magnetic field that propagates through said vessel and around said susceptor in said interface;
• inducing eddy currents in said susceptor with said magnetic field and resistively heating said susceptor with said eddy currents to soften said thermoplastic in said faying surfaces;
• moving said coil axially along said vessel while inducing said eddy currents in said susceptor with said magnetic field to create a moving melt pool of said thermoplastic in said faying surfaces while exerting said force on said vessel to press said vessel against one part and thereby press said faying surface of that part with a uniformly distributed pressure against said faying surface of the other part and to hold said parts in contact while said softened thermoplastic in both faying surfaces infuses through the susceptor and interdiffuses together into a continuous thermoplastic weld.

Tooling for forming a thermoplastic weld along a bond line between at least two, interfacing, prefabricated, fiber-reinforced thermoplastic composite parts, the parts being in registration to define the bond line, comprising:

• a fluid pressure chamber in contact with at least one part for applying a substantially uniform pressure along the bond line;
• (b) an induction coil in the chamber for generating a magnetic field to heat and soften the parts at the bond line to form the thermoplastic weld;
• (c) an electrical power source coupled to the coil to energize the coil to generate the magnetic field;
• and
• (d) motive means associated with the coil for moving the coil in the chamber over the bond line.

A process for forming a thermoplastic weld along a bond line along an interface between at least two fiber-reinforced thermoplastic composite parts, comprising the steps of:

• (a) assembling the parts to define the bond line;
• (b) applying a substantially uniform pressure to the entire bond line by exerting pressure with a pressurized liquid to at least one part;
• and
• (c) moving an energized induction coil over the surface of one part while applying the pressure, the coil generating a magnetic field that heats and softens the parts along the bond line to form the thermoplastic weld.